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

Abstract

Provided are polymer compositions for binders for electrochemical devices that can improve the coulombic efficiency of electrochemical devices. [Solution] The polymer composition is used as a binder for electrochemical devices, and contains 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-(CF2) m-1 -COO) p M 1 (wherein m is 4 to 20, M 1 is H, metal atom, NR 5 4(R 5 may be the same or different, and may be H or an organic group having 1 to 10 carbon atoms, and p is 1 or 2. General formula (2):(H-(CF2) 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), and q is 1 or 2.

Description

[Technical Field]

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

[0002] Secondary batteries such as lithium-ion secondary batteries have high voltage, high energy density, low self-discharge, little memory effect, and can be made extremely lightweight, and are therefore used in small, portable electrical and electronic devices such as notebook computers, mobile phones, smartphones, tablet computers, and ultrabooks, and are also being put into practical use as a wide range of power sources, including on-board power supplies for driving automobiles and large-scale stationary power supplies. There is a demand for even higher energy densities in secondary batteries, and further improvements in their battery characteristics are also required.

[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. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2017-517862 [Patent Document 2] International Publication No. 2021 / 181887 [Patent Document 3] International Publication No. 2021 / 181888 [Patent Document 4] International Publication No. 2021 / 192541 [Patent Document 5] International Publication No. 2022 / 138942 [Patent Document 6] International Publication No. 2022 / 138939 [Patent Document 7] International Publication No. 2023 / 286787 [Patent Document 8] International Publication No. 2022 / 234227 [Patent Document 9] International Publication No. 2023 / 094623 Summary of the Invention [Problem to be solved by the invention]

[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. [Means for solving the problem]

[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 a compound represented by the following general formula (1) and a compound represented by the following general formula (2): General formula (1):(H-(CF2) m-1 -COO) p M 1 (wherein m is 4 to 20. M 1 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), 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-(CF2)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.

[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 a 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 the polymer composition according to any one of the present disclosures (1) to (5) in the form of 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 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): General formula (1):(H-(CF2) m-1 -COO) p M 1 (wherein m is 4 to 20. M 1 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), 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-(CF2) 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.

[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 above 330°C.

[0019] The present disclosure (12) is the binder for electrochemical devices according to any one of the present disclosures (8) to (11), wherein 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 fibrillating polymer has a thermal instability index (TII) of 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% by 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 mass % and not more than 97 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), wherein 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) is 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), wherein 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 the 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 containing 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 including the electrode according to the present disclosure (32). [Effects of the Invention]

[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. DETAILED DESCRIPTION OF THE INVENTION

[0042] In this disclosure, "organic group" means a group containing one or more carbon atoms or a group formed by removing one hydrogen atom from an organic compound. 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): General formula (1):(H-(CF2) m-1 -COO) p M 1 (wherein m is 4 to 20. M 1 is H, metal atom, NR 5 4(R 5may be the same or different and are H or an organic group having 1 to 10 carbon atoms), 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-(CF2) 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.

[0045] The present disclosure also provides a polymer composition for use 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 greater (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 structure, can improve the Coulomb efficiency of electrochemical devices. Furthermore, a mixture sheet can be produced even with a small amount of addition. Furthermore, since a mixture sheet having 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), and processing can be performed under a wider range of molding conditions. When the polymer composition of the present disclosure is in the form of a powder, flowability can also be improved. The polymer composition of the present disclosure can be used in a dry process, which eliminates the need for a large amount of a dispersion medium such as water or an organic solvent, and allows for a wide selection of electrode active materials and solid electrolytes to be combined, which is advantageous in terms of production process, and also reduces the steps and costs associated with the use of a dispersion medium. Furthermore, the polymer composition of the present disclosure has excellent binding strength with active materials and electrolytes, so that 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=-0.0579logMn+2.6113 In the formula, SSG is the standard specific gravity of the polymer, which is measured by the water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895 89.

[0049] The above-mentioned 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 with 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 them is considered to be 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 preferably has a TII of 10 or more. A fibrillating polymer having a TII of 10 or more can be obtained by using a hydrocarbon surfactant. 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 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 is 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 lower. 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 fibrillating polymer that has not been heated to temperatures above 300°C is weighed out, placed in a special aluminum pan, and measured using a TG / DTA (thermogravimetric and differential thermal 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 measuring the temperature at which a 0.1% mass loss occurs.

[0052] The fibrillating polymer may have a 1.0% mass loss temperature of 492°C or less. A fibrillating polymer having a 1.0% mass loss temperature of 492° C. or less can be obtained by using a hydrocarbon surfactant. The 1.0% mass loss temperature is a value measured by the following method. Approximately 10 mg of fibrillating polymer that has not been heated to temperatures above 300°C is weighed out and placed in a special aluminum pan for measurement using a TG / DTA (thermogravimetric and 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 from 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. Preferred fibrillating polymers are TFE-based polymers, polyethylene, and polyester, with TFE-based polymers being more preferred.

[0054] The TFE-based polymer may be a homopolymer of TFE, or a TFE copolymer containing polymerization units based on TFE (TFE units) and polymerization units based on a modified monomer copolymerizable with TFE (modified monomer units). The TFE-based polymer may be polytetrafluoroethylene (PTFE), which includes a TFE homopolymer and a modified PTFE containing 99.0% by mass or more of TFE units and 1.0% by mass or less of modified monomer units. The TFE-based polymer is preferably PTFE, and more preferably modified PTFE, 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. In the present disclosure, a homopolymer of TFE refers to one in which the content of modified monomer units relative to all polymerized units is less than 0.0001% by 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 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 the TFE polymer that is derived from the 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] The modifying monomer is not particularly limited as long as it can be copolymerized with TFE, and examples thereof include perfluoroolefins such as hexafluoropropylene (HFP); hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride (VdF); perhaloolefins such as chlorotrifluoroethylene (CTFE); perfluorovinyl ethers; perfluoroallyl ethers; (perfluoroalkyl)ethylenes, ethylenes, and monomers having polar groups. The modifying monomers used may be one type or multiple types.

[0058] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorovinyl ethers represented by the following general formula (A): CF2=CF-ORf 1 (A) (In the formula, Rf1 represents a perfluoroorganic group. ) and perfluorounsaturated compounds represented by the following formulas are included. 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) in which Rf 1 is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, Rf 1 is the following formula:

[0062] [ka]

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

[0064] [ka]

[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): CF2=CF-CF2-ORf 2 (B) (In the formula, Rf 2 represents a perfluoroorganic group.

[0068] Above Rf 2 is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. The perfluoroallyl ether is preferably at least one selected from the group consisting of CF2=CF-CF2-O-CF3, CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, more preferably at least one selected from the group consisting of CF2=CF-CF2-O-C2F5, CF2=CF-CF2-O-C3F7, and CF2=CF-CF2-O-C4F9, and even more preferably CF2=CF-CF2-O-CF2CF2CF3.

[0069] The modified monomer is represented by the following general formula (i): CX 1 X 2 =CX 3 X 4 (i) (In the formula, X 1 ~X 3 are each independently H or F. 4 is F, Cl, Rf or O-Rf. Rf is a perfluoro organic 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 the non-fluorine-containing monomer include 3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH"), succinic anhydride, fumaric anhydride, maleic anhydride, and other non-fluorine-containing monomers having an acid anhydride residue; vinyl sulfonic acid, and other non-fluorine-containing monomers having a sulfo group; glycidyl vinyl ether, glycidyl allyl ether, and other non-fluorine-containing monomers having an epoxy group (glycidyl group); aminoalkyl vinyl ether, aminoalkyl allyl ether, and other non-fluorine-containing monomers having an amino group; (meth)acrylamide, methylolacrylamide, and other non-fluorine-containing monomers having an amide group; and acrylonitrile, methacrylonitrile, and other non-fluorine-containing monomers having a nitrile group. Among these, a fluorine-free monomer having a carboxy group and a fluorine-free monomer having an acid anhydride residue are preferred, a fluorine-free monomer having an acid anhydride residue is more preferred, and a cyclic fluorine-free monomer having an acid anhydride residue is even more preferred.

[0073] The polar group-containing monomer preferably includes a modified monomer having a functional group reactive in radical polymerization and a hydrophilic group (hereinafter referred to as "modified monomer (A)").

[0074] Examples of the hydrophilic group in the modified monomer (A) include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, and -COOM (in each formula, M represents H, a metal atom, or NR 7 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7 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. ) are examples of the hydrophilic group. Of these, -SO3M or -COOM is preferred. R 7 As for H or C 1-10 is preferably an organic group represented by the formula: 1-4 The organic group is more preferably H or C 1-4 More preferred are alkyl groups of the formula: The metal atom may be a monovalent or divalent metal atom, such as an alkali metal (Group 1) or an alkaline earth metal (Group 2), with Na, K, or Li being preferred.

[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- (In the formula, X e , X f and X g are each independently F, Cl, H, CF3, CF2H, CFH2, or CH3; and R is a linking group. The linking group for R can be represented by the formula: a Preferred linking groups include -CH=CH2 and -CF=CH 2、 -CH=CF 2、Examples include groups having an unsaturated bond such as -CF=CF2, -CH2-CH=CH2, -CF2-CF=CH2, -CF2-CF=CF2, -(C=O)-CH=CH2, -(C=O)-CF=CH2, -(C=O)-CH=CF2, -(C=O)-CF=CF2, -(C=O)-C(CH3)=CH2, -(C=O)-C(CF3)=CH2, -(C=O)-C(CH3)=CF2, -(C=O)-C(CF3)=CF2, -O-CH2-CH=CH2, -O-CF2-CF=CH2, -O-CH2-CH=CF2, and -O-CF2-CF=CF2.

[0076] The modified monomer (A) has a functional group capable of reacting by radical polymerization, and therefore, when used in polymerization, it is presumed that it reacts with the fluorine-containing monomer at the initial stage of the polymerization reaction, forming highly stable particles having hydrophilic groups derived from the modified monomer (A). Therefore, it is considered that the number of particles increases when polymerization is carried out in the presence of the modified monomer (A).

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

[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). CF2=CF-(CF2) n1 -Y 3 (4a) (wherein n1 represents an integer of 1 to 10, and Y 3 -SO3M 1 or -COOM 1 represents M 1 represents H, NH4 or an alkali metal. CF2=CF-(CF2C(CF3)F) n2 -Y 3 (4b) (wherein n2 represents an integer of 1 to 5, and Y 3 is the same as the definition above.) CF2=CF-O-(CFX 1 ) n3 -Y 3 (4c) (In the formula, X 1 represents F or CF3, n3 represents an integer of 1 to 10, and Y 3 is the same as the definition above.) CF2=CF-O-(CF2CFX 1 O) n4 -CF2CF2-Y 3 (4d) (wherein n4 represents an integer of 1 to 10, and Y 3 and X 1 is the same as the definition above.) CX 2 2=CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-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, and Y 3 is the same as the definition above.) The alkali metals include Na, K, and the like.

[0080] In the formula (4a), n1 is preferably an integer of 5 or less, and more preferably an integer of 2 or less. 3 -COOM is advantageous in that it provides adequate water solubility and surface activity. 1 Preferably, M 1 is preferably H or NH4, since it is unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0081] The perfluorovinyl alkyl compound represented by the above formula (4a) is, for example, CF2=CFCF2COOM 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 in terms of emulsifying ability, and Y 3-COOM is advantageous in that it provides adequate water solubility and surface activity. 1 Preferably, M 1 is preferably H or NH4, since it is unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0083] In the formula (4c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y 3 -COOM is advantageous in that it provides adequate water solubility and surface activity. 1 It is preferable that the above M 1 is preferably H or NH4 in terms of improving dispersion stability.

[0084] In the above formula (4d), the above X 1 is preferably -CF3 from the viewpoint of surface activity, n4 is preferably an integer of 5 or less from the viewpoint of water solubility, and Y 3 COOM has the advantage of providing moderate water solubility and surface activity. 1 It is preferable that the above M 1 is preferably H or NH4.

[0085] Examples of the perfluorovinyl ether compound represented by the above formula (4d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM 1 (In the formula, M 1 represents H, NH4 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 moderate water solubility and surface activity. 1 It is preferable that the above M 1 is preferably H or NH4, since it is unlikely to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0087] Examples of the perfluorovinyl alkyl compound represented by the formula (4e) include CH2=CFCF2OCF(CF3)COOM 1 , CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM1(where 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. Examples of TFE polymers having a core-shell structure include TFE polymers containing a core of a high molecular weight TFE polymer and a shell of a lower molecular weight TFE polymer or TFE copolymer in the particles. Also included are modified PTFE particles containing a core of a high molecular weight PTFE and a shell of a lower molecular weight PTFE or modified PTFE. Examples of such modified PTFE include the PTFE described in JP-A-2005-527652.

[0091] The TFE-based polymer is preferably non-melt processable. In this specification, non-melt-processable means that the melt flow rate (MFR) is less than 0.25 g / 10 min, preferably less than 0.10 g / 10 min, more preferably 0.05 g / 10 min or less, and even more preferably 0.01 g / 10 min or less. The MFR 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 having an inner diameter of 2.095 mm and a length of 8 mm at 372°C under a load of 5 kg per 10 min.

[0092] The TII of the TFE-based 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 is preferably 80 or less, more preferably 50 or less, from the viewpoints of further improving the Coulomb efficiency of an electrochemical device, further reducing the amount added, further improving the adhesion between the mixture sheet and the substrate, and further improving powder fluidity. A TFE-based polymer having a TII of 10 or more can be obtained by using a hydrocarbon-based 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 even greater 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 fact that the fibrillating polymer is 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, 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 melting point of the thermoplastic resin is preferably 100°C or higher, more preferably 115°C or higher, even more preferably 130°C or higher, even more preferably 160°C or higher, especially preferably 210°C or higher, even more especially preferably 250°C or higher, even more especially preferably 255°C or higher, particularly preferably 295°C or higher, and preferably less than 324°C, also 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, and also preferably 135°C or lower. In this specification, the melting point is the temperature corresponding to the maximum value on the heat of fusion curve when the temperature is increased 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 per 10 min from 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 (for example, 372°C for PFA and FEP, which will be described later, and 297°C for ETFE) and a load (for example, 49 N (5 kg) for PFA, FEP, and ETFE).

[0101] The fluoropolymer is preferably a melt-processable fluororesin, such as 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], and polyvinylidene fluoride [PVdF].

[0102] Although the PFA is not particularly limited, 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 units are too few, mechanical properties tend to deteriorate, while if they are too many, the melting point tends to become too high and moldability tends to deteriorate. 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, and the like. 3 Z 4 =CZ 5 (CF2) 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.) and a vinyl monomer represented by CF2=CF-OCH2-Rf 7 (In the formula, Rf 7 represents a perfluoroalkyl group having 1 to 5 carbon atoms.

[0103] The PFA may have a functional group, which 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 above functional groups in their constituent units include PFAs obtained by copolymerizing a monomer having a polar group. Examples of PFA containing the above functional group at the end group of the polymer main chain include PFA having a functional group as the 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 group-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 monomer having a polar group in the PFA may be a non-fluorine-containing 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 the non-fluorine-containing monomer include 3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH"), succinic anhydride, fumaric anhydride, maleic anhydride, and other non-fluorine-containing monomers having an acid anhydride residue; vinyl sulfonic acid, and other non-fluorine-containing monomers having a sulfo group; glycidyl vinyl ether, glycidyl allyl ether, and other non-fluorine-containing monomers having an epoxy group (glycidyl group); aminoalkyl vinyl ether, aminoalkyl allyl ether, and other non-fluorine-containing monomers having an amino group; (meth)acrylamide, methylolacrylamide, and other non-fluorine-containing monomers having an amide group; and acrylonitrile, methacrylonitrile, and other non-fluorine-containing monomers having a nitrile group. Among these, a fluorine-free monomer having a carboxy group and a fluorine-free monomer having an acid anhydride residue are preferred, a fluorine-free monomer having an acid anhydride residue is more preferred, and a cyclic fluorine-free monomer having an acid anhydride residue is even more preferred.

[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, such as 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 not particularly limited, the FEP is preferably 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. 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 not particularly limited, the FEP is preferably 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. 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 with perfluoro(alkyl vinyl ether)s as monomers copolymerizable with TFE and HFP, in a range of 0.1 to 2 mass% of the total monomers. If the TFE unit content is too low, the mechanical properties tend to decrease, while if it is too high, the melting point tends to become too high and moldability tends to decrease.The above-mentioned FEP is also preferably 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 the TFE units and HFP units is 90 to 99.9 mol %.Examples of the monomer copolymerizable with TFE and HFP include PAVE and alkyl perfluorovinyl ether derivatives. The FEP may also have a functional group, such as those described for the PFA.

[0109] The melting point of the FEP is lower than that of the 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] The ETFE is preferably 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. 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. The ETFE may be a copolymer consisting of TFE, ethylene, and a monomer copolymerizable with TFE and ethylene. The copolymerizable monomer may be a copolymer represented by the following formula: CH2=CX 5 Rf 3 , CF2=CFRf 3 , CF2=CFORf 3 , CH2=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 CF2=CFRf 3 , CF2=CFORf 3 and CH2=CX 5 Rf 3 Fluorine-containing vinyl monomers represented by the formula: 4 (In the formula, Rf 4 represents a perfluoroalkyl group having 1 to 5 carbon atoms. 3 is a fluoroalkyl group having 1 to 8 carbon atoms, CH2=CX 5 Rf 3The fluorine-containing vinyl monomer represented by the formula (I) 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 (CH2=CFCF2CF2CF2H), or 2-trifluoromethyl-3,3,3-trifluoropropene ((CF3)2C=CH2). The content 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 with a monomer copolymerizable with TFE and ethylene in an amount of 0 to 20% by mass of the total monomers. Preferably, the ratio of TFE:ethylene:TFE and monomer copolymerizable with ethylene is (63-94):(27-2):(1-10). The ETFE may have a functional group, such as those described for the 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 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, and particularly preferably 215°C or higher, and is preferably lower 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 270°C or lower. The melting point of the EFEP is preferably 160°C or higher and 200°C or lower.

[0113] The copolymerization ratio (mol %) 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 fluorine-containing monomers such as perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), chlorotrifluoroethylene, 2-chloropentafluoropropene, and perfluorinated vinyl ethers (for example, perfluoroalkoxy vinyl ethers such as CF3OCF2CF2CF2OCF=CF2), perfluoroalkyl vinyl ethers, perfluoro-1,3-butadiene, trifluoroethylene, hexafluoroisobutene, vinyl fluoride, ethylene, propylene, and alkyl vinyl ethers. BTFB (HC=CH-CF2-CF2-Br), BDFE (FC=CHBr), and BTFE (FC-CFBr) are preferred.

[0114] The melting point of the above 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 polymerized units based on VdF (also referred to as "VdF units") in an amount of 80.0 to 90.0 mol % based on the total polymerized 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, and more preferably 82.0 mol % or more, of VdF units relative to the total polymerized units. When the VT 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. The VT more preferably contains 89.0 mol % or less of VdF units, further preferably 88.9 mol % or less, and particularly preferably 88.8 mol % or less, based on the total polymerized units.

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

[0117] Examples of the monomers 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 also -SO3M, -OSO3M, -COOM, -OPO3M (M represents an alkali metal) and amine polar groups such as -NHR as described in JP-A-7-201316. 1 , -NR 2 R 3 (R 1 , R 2 , R 3 represents an alkyl group), for example, CH2=CH-CH2-Y, CH2=C(CH3)-CH2-Y, CH2=CH-CH2-O-CO-CH(CH2COOR 4 )-Y, CH2=CH-CH2-O-CH2-CH(OH)-CH2-Y, CH2=C(CH3)-CO-O-CH2-CH2-CH2-Y, CH2=CH-CO-O-CH2-CH2-Y, CH2=CHCO-NH-C(CH3)2-CH2-Y (Y is a hydrophilic polar group, or R 4 represents an alkyl group), and other examples include maleic acid and maleic anhydride. Furthermore, CH2=CH-CH2-O-(CH2) n -OH(3≦n≦8),

[0118] [ka]

[0119] CH2=CH-CH2-O-(CH2-CH2-O) n -H(1≦n≦14), CH2=CH-CH2-O-(CH2-CH(CH3)-O)n Hydroxylated allyl ether monomers such as -H(1≦n≦14) and carboxylated and / or -(CF2) n Allyl ether and ester monomers substituted with -CF3 (3≦n≦8), such as CH2=CH-CH2-O-CO-C2H4-COOH, CH2=CH-CH2-O-CO-C5H 10 -COOH, CH2=CH-CH2-O-C2H4-(CF2) n CF3, CH2=CH-CH2-CO-O-C2H4-(CF2) n CF3, CH2=C(CH3)-CO-O-CH2-CF3, etc. can also be used as copolymerizable monomers. Incidentally, previous research has led to the conclusion that even compounds other than those containing polar groups, such as those mentioned above, can improve adhesion to current collectors made of aluminum or copper foil by slightly reducing the crystallinity of copolymers of vinylidene fluoride and tetrafluoroethylene, giving the material flexibility. For example, unsaturated hydrocarbon monomers such as ethylene and propylene (CH2=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, and CF2=CF-OC have been shown to improve adhesion. n F 2n+1 (n is an integer of 1 or more), CH2=CF-C n F 2n+1 (n is an integer of 1 or greater), CH2=CF-(CF2CF2) n H (n is an integer of 1 or more), and CF2=CF-O-(CF2CF(CF3)O) m -C n F 2n+1 (m and n are integers of 1 or more) can also be used. Other formulas (1):

[0120] [ka]

[0121] (wherein Y is —CHOH, —COOH, a carboxylate, a carboxy ester group or an epoxy group; X and X 1 are the same or different and are all hydrogen atoms or fluorine atoms, R f It 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 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. 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 polymerized 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, 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) at 50° C. using N,N-dimethylformamide as a solvent.

[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) at 50° C. using N,N-dimethylformamide as a solvent.

[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 -SO3M, -OSO3M, -COOM, -OPO3M (wherein M represents an alkali metal) and amine polar groups such as -NHR, as described in JP-A-7-201316. 1 , -NR 2 R 3 (R 1 , R 2 , R 3 represents an alkyl group), for example, CH2=CH-CH2-Y, CH2=C(CH3)-CH2-Y, CH2=CH-CH2-O-CO-CH(CH2COOR 4)-Y, CH2=CH-CH2-O-CH2-CH(OH)-CH2-Y, CH2=C(CH3)-CO-O-CH2-CH2-CH2-Y, CH2=CH-CO-O-CH2-CH2-Y, CH2=CHCO-NH-C(CH3)2-CH2-Y (Y is a hydrophilic polar group, or R 4 represents an alkyl group), and other examples include maleic acid and maleic anhydride. Furthermore, CH2=CH-CH2-O-(CH2) n -OH(3≦n≦8), [ka] CH2=CH-CH2-O-(CH2-CH2-O) n -H(1≦n≦14), CH2=CH-CH2-O-(CH2-CH(CH3)-O) n Hydroxylated allyl ether monomers such as -H(1≦n≦14) and carboxylated and / or -(CF2) n Allyl ether and ester monomers substituted with -CF3 (3≦n≦8), such as CH2=CH-CH2-O-CO-C2H4-COOH, CH2=CH-CH2-O-CO-C5H 10 -COOH, CH2=CH-CH2-O-C2H4-(CF2) n CF3, CH2=CH-CH2-CO-O-C2H4-(CF2) n CF3, CH2=C(CH3)-CO-O-CH2-CF3, etc. can also be used as copolymerizable monomers. Incidentally, previous research has suggested that compounds other than those containing polar groups can also improve adhesion to current collectors made of aluminum or copper foil by slightly reducing the crystallinity of PVdF and making the material more flexible. For example, unsaturated hydrocarbon monomers such as ethylene and propylene (CH2=CHR, where R is a hydrogen atom, alkyl group, or halogen such as Cl), as well as fluorine-based monomers such as trifluorochloroethylene, hexafluoropropylene, hexafluoroisobutene, and CF2=CF-OC n F 2n+1 (n is an integer of 1 or more), CH2=CF-C n F 2n+1(n is an integer of 1 or greater), CH2=CF-(CF2CF2) n H (n is an integer of 1 or more), and CF2=CF-O-(CF2CF(CF3)O) m -C n F 2n+1 (m and n are integers of 1 or more) can also be used. Other formulas (1):

[0128] [ka] (wherein Y is —CHOH, —COOH, a carboxylate, a carboxy ester group or an epoxy group; X and X 1 are the same or different and are all hydrogen atoms or fluorine atoms, R f It 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 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 above PVdF, 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 adhesiveness of the obtained electrode will be low, whereas if it exceeds 1,400,000, the electrode mixture will be prone to gelling during preparation. The number average molecular weight is preferably 200,000 or more, more preferably 250,000 or more, 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-based 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, and even more preferably 2 μm or less, in terms of being able to be uniformly dispersed and of providing a composite sheet with excellent strength and uniformity, and is preferably 0.1 μm or more, and more preferably 0.5 μm or more. The average particle size of the VdF polymer can be adjusted, for example, by pulverization. The average particle size was determined based on the particle size distribution (volume basis) obtained by dry measurement using a Beckman Coulter laser diffraction particle size analyzer (LS13 320) at a vacuum pressure of 20 mH2O. The average particle size was defined as the particle size corresponding to 50% of the integrated particle size distribution.

[0137] The VdF polymer preferably does not contain a fluorine-containing surfactant. The VdF polymer not containing a fluorine-containing surfactant can be produced, for example, by suspension polymerization. As described in the Examples below, whether a VdF-based polymer does not contain a fluorine-containing surfactant can be confirmed by checking that the amount of the fluorine-containing surfactant measured by liquid chromatography-mass spectrometry is 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. The elastomer is preferably a fluoroelastomer. 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, which 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, and 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 an especially 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 represented by the general formula (1-1): CH2=CFRf1(1-1) (wherein Rf1 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 carbon atoms), General formula (2-1) CHF=CHRf2(2-1) (wherein Rf2 is a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms, and when the carbon number is 2 or more, it may contain an oxygen atom between carbon atoms); fluorine-free monomers such as ethylene (Et), propylene (Pr), and alkyl vinyl ether, monomers that provide crosslinkable groups (cure sites), and reactive emulsifiers; and these monomers and compounds can be used alone or in combination of two or more.

[0143] In the above general formula (1-1), Rf1 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. The fluorinated alkyl group of Rf1 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 a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. Furthermore, the fluorinated alkyl group of Rf1 may have hydrogen atoms substituted with substituents other than fluorine atoms, but preferably does not contain any substituents other than fluorine atoms. The fluorinated alkoxy group of Rf1 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 a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. The fluorinated alkoxy group of Rf1 may have hydrogen atoms substituted with substituents other than fluorine atoms, but preferably does not contain any substituents other than fluorine atoms. The number of carbon atoms in Rf1 is preferably 1 to 10, more preferably 1 to 6, further preferably 1 to 4, and particularly preferably 1.

[0144] In the above formula (2-1), Rf2 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 fluorinated alkoxy group each have two or more carbon atoms, they can contain an oxygen atom (—O—) between carbon atoms. The fluorinated alkyl group of Rf2 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 a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. Furthermore, the fluorinated alkyl group of Rf2 may have hydrogen atoms substituted with substituents other than fluorine atoms, but preferably does not contain any substituents other than fluorine atoms. The fluorinated alkoxy group of Rf2 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 a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atom are substituted with fluorine atoms. The fluorinated alkoxy group of Rf2 may have hydrogen atoms substituted with substituents other than fluorine atoms, but preferably does not contain substituents other than fluorine atoms. The number of carbon atoms in Rf2 is preferably 1 to 10, more preferably 1 to 6, still more preferably 1 to 4, and particularly preferably 1.

[0145] Among these, copolymerized units preferably comprise hexafluoropropylene (HFP), tetrafluoroethylene (TFE), 2,3,3,3-tetrafluoropropylene, 1,3,3,3-tetrafluoropropylene, or perfluoroalkyl vinyl ether (PAVE). Furthermore, it is most preferable that at least a portion of the copolymerized units be hexafluoropropylene (HFP). Examples of vinylidene fluoride-based 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. The PAVE has the formula: CF2 = CFOCF2ORf c (In the formula, Rf cIt is also possible to use perfluorovinyl ethers represented by the formula (CF2=CFOCF2OCF3, CF2=CFOCF2OCF2CF3, or CF2=CFOCF2OCF2CF2OCF3), where CF2=CFOCF2OCF2CF2OCF3 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. For example, it is preferable to use CF2=CFOCF2OCF3, CF2=CFOCF2OCF2CF2OCF3, or CF2=CFOCF2OCF2CF2OCF3.

[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 copolymer of VdF / fluorine-containing monomer represented by formula (1-1) or (2-1). Furthermore, it is more preferable that the VdF-based fluoroelastomer contains at least one comonomer selected from the group consisting of TFE, HFP, and PAVE as a 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 (45-85) / (55-15) (mol%), more preferably (50-80) / (50-20) (mol%), and even more preferably (60-80) / (40-20) (mol%). The VdF / HFP composition is also preferably (50-78) / (50-22) (mol%).

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

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

[0152] The VdF / TFE / PAVE copolymer preferably has a VdF / TFE / PAVE composition of (40 to 80) / (3 to 40) / (15 to 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 (40-90) / (0-25) / (0-40) / (3-35) (mol %), and more preferably (40-80) / (3-25) / (3-40) / (3-25) (mol %).

[0155] The VdF / fluorine-containing monomer (1-1) or (2-1) 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 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 ratio 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. Preferred monomers other than VdF and the fluorine-containing monomer (1-1) or (2-1) are 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, which are exemplified above as comonomers for VdF, with PMVE, CTFE, HFP, and TFE being more preferred.

[0156] The TFE / Pr-based fluorine-containing elastomer refers to a fluorine-containing copolymer consisting of 45-70 mol % of TFE and 55-30 mol % of Pr. In addition to these two components, it may contain 0-40 mol % of a specific third component (such as 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 (35-75) / (25-50) / (0-15) (mol %), more preferably (45-75) / (25-45) / (0-10) (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, and these 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 the fluorine atoms contained therein was determined to calculate the fluorine content.

[0161] In the present disclosure, the composition ratio of each repeating unit of the fluoroelastomer is a value measured by NMR, specifically, a value measured by the following solution NMR method. Measurement equipment: 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 conventional methods 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 copolymer 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 copolymer 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 -CH3, 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 -CH3, X 2is an iodine atom or a bromine atom.) an iodine- or bromine-containing monomer represented by the general formula: CF2=CFO(CF2CF(CF3)O) m (CF2) 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, CH2=CFCF2O(CF(CF3)CF2O) m (CF(CF3)) n -X 4 (wherein m is an integer of 0 to 5, n is an integer of 1 to 3, X 4 is a cyano group, a carboxy group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or —CH OH.

[0166] Among these, at least one selected from the group consisting of CF2=CFOCF2CF(CF3)OCF2CF2CN, CF2=CFOCF2CF(CF3)OCF2CF2COOH, CF2=CFOCF2CF2CH2I, CF2=CFOCF2CF(CF3)OCF2CF2CH2I, CH2=CFCF2OCF(CF3)CF2OCF(CF3)CN, CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOH, and CH2=CFCF2OCF(CF3)CF2OCF(CF3)CH2OH is preferred. Furthermore, although the polymer may contain a repeating unit based on a monomer that provides a crosslinking site, in one embodiment of the present disclosure, no crosslinking agent is contained.

[0167] To ensure good adhesion, flexibility, and solubility in solvents, the fluoroelastomer preferably has a number-average molecular weight (Mn) of 7,000 to 5,000,000, a mass-average molecular weight (Mw) of 10,000 to 10,000,000, and an Mw / Mn ratio of 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, and 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 of the following inequality: 0.01≦([-CH2OH]+[-COOH]) / ([-CH3]+[-CF2H]+[-CH2OH]+[-CH2I]+[-OC(O)RH]+[-COOH])≦0.25 (wherein RH is an alkyl group having 1 to 20 carbon atoms) is preferably satisfied. By making the terminal functional group satisfy the above formula, the adhesiveness and flexibility are good, and the product has excellent functions.

[0170] Incidentally, satisfying the above general formula does not mean that the fluorinated copolymer has all of the functional groups [-CH], [-CFH], [-CHOH], [-CHI], [-OC(O)RH], and [-COOH], but means that, among these, the ratio of the number of terminal groups present in the fluorinated copolymer 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 a solvent, and then the measurement is performed. The reference peak is the peak top of acetone at 2.05 ppm. Measurement equipment: Varian VNMRS400 Resonance frequency: 399.74 (Sfrq) Pulse width: 45° Each end corresponds to the following peak position: [-CH3]: 1.72 to 1.86 ppm [-CF2H]: 6.1 to 6.8 ppm [-CH2OH]: 3.74~3.80ppm [-CH2I]: 3.87 to 3.92 ppm [-OC(O)RH]: 1.09 to 1.16 ppm [-COOH]: 10-15 ppm The amount of functional groups is calculated from the intensity of each peak based on the integrated value of each peak identified by the above-mentioned measurement, and the amount is calculated using the following formula based on the results. ([-CH2OH]+[-COOH]) / ([-CH3]+[-CF2H]+[-CH2OH]+[-CH2I]+[-OC(O)RH]+[-COOH])

[0173] The method for making [—CHOH] and [—COOH] 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 for each of them. The copolymer may 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 carried out by adding an inorganic salt such as aluminum sulfate or an inorganic acid, by applying mechanical shearing force, or by freezing the dispersion. In the case of suspension polymerization, the copolymer can be obtained by recovering it 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] As the thermoplastic polymer, at least one selected from the group consisting of perfluoropolymers and VdF-based polymers is preferred, at least one selected from the group consisting of PFA, FEP, PVdF, VT, and VdF-based fluoroelastomers is more preferred, at least one selected from the group consisting of PFA, FEP, PVdF, VT, VdF / HFP copolymer, VdF / TFE / HFP copolymer, and VdF / 2,3,3,3-tetrafluoropropylene copolymer is even more preferred, at least one selected from the group consisting of PFA, FEP, PVdF, VT, and VdF / HFP copolymer is even more preferred, and at least one selected from the group consisting of PVdF and VT is particularly preferred. 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 fluidity. 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-(CF2) m-1 -COO) p M 1 (wherein m is 4 to 20. M 1 is H, metal atom, NR 5 4(R 5may be the same or different and are H or an organic group having 1 to 10 carbon atoms), 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-(CF2) 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 mentioned above includes monovalent and divalent metal atoms, such as alkali metals (Group 1) or alkaline earth metals (Group 2), and specific examples thereof include Na, K, and Li. The Four Rs 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 5,000 ppb by mass or less, more preferably 1,000 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 mass ppb, 1 mass ppb, 10 mass ppb, or 50 mass ppb.

[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 mass ppm or less relative to the polymer composition, preferably 5000 mass ppb or less, more preferably 1000 mass ppb or less, even more preferably 500 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 10 mass ppb or less, 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.

[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 usually 100 ppm by mass to 10% by mass. 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).

[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-(CF2)8-SO3) 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, 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. 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, more preferably 15 mass ppb or less, and even more preferably 10 mass ppb or less relative to the TFE-based polymer. 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 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 it is preferable that the content of each of these compounds is 1000 ppb by mass or less relative to the polymer composition. General formula (4):(H-(CF2) 15 -COO) p M 1 (In the formula, M 1 is H, metal atom, NR 5 4(R 5 may be the same or different and are H, 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-(CF2) 16 -COO) p M 1 (In the formula, M 1 is H, 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 preferably 500 mass ppb or less, 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 preferably 500 mass ppb or less, 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 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 it is preferable that the content of each of these compounds is 1000 ppb by mass or less relative to the polymer composition. General formula (5):(H-(CF2) 13 -COO) p M 1 (In the formula, M 1 is H, metal atom, NR 5 4(R 5 may be the same or different and are H, 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-(CF2) 14 -COO) p M 1 (In the formula, M 1 is H, 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 preferably 500 mass ppb or less, 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 preferably 500 mass ppb or less, 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, it is advantageous in terms of production processes because it allows for a wide range of electrode active materials and solid electrolytes to be combined. "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 time, and the average value is determined 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)×100

[0196] The polymer composition of the present disclosure is preferably substantially free of fluorine-containing compounds having a molecular weight of not more than 1000. "Substantially free of fluorine-containing compounds" means that the amount of the fluorine-containing compounds is 25 ppb by mass 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.

[0197] The amount of the fluorine-containing compound having a molecular weight of 1,000 or less is measured by the following method. Weigh out 1 g of sample, add 10 g (12.6 ml) of methanol, and ultrasonicate for 60 minutes to obtain an extract. The resulting extract is concentrated using an appropriate nitrogen purge, 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 standard substance content are prepared, and LC / MS analysis is performed on each solution. The relationship between content and area relative to that content is plotted, and a calibration curve is drawn. Using the above calibration curve, the area of ​​the LC / MS chromatogram of the fluorine-containing compounds in the extract is converted to the content of the fluorine-containing compounds. The lower limit of quantification 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 a fluorine-containing compound having a hydrophilic group and a molecular weight of 1000 g / mol or less. The molecular weight of the fluorine-containing compound is preferably 800 or less, and 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 one that is used during polymerization. The fluorine-containing compound having a molecular weight of 1,000 or less may be a compound that is not added during polymerization, for example, a compound that is produced as a by-product during polymerization. When the fluorine-containing compound having a molecular weight of 1000 or less contains an anionic moiety and a cationic moiety, it means a compound containing fluorine 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] The hydrophilic group may be, for example, -COOM, -SO2M, or -SO3M, where -COOM, -SO3M (in each formula, M is H, a metal atom, NR 14. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein 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(CF2) n1 In the case of COOM, "F(CF2) n1 The "COO" part. The anionic fluorine-containing surfactant may be a compound represented by the following general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl or F. n0 is a linear, branched or cyclic alkylene group having 3 to 20 carbon atoms, in which some or all of the H's are substituted with F, and the alkylene group may contain one or more ether bonds, and some of the H's may be substituted with Cl. Y 0 is an anionic group. Y 0 The anionic group may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, metal atom, NR 1 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 1 is H or an organic group. The metal atom includes alkali metals (Group 1) and alkaline earth metals (Group 2), such as Na, K, or Li. R 1 As for H or C 1-10 may be an organic group of H or C1-4 may be an organic group of H or C 1-4 The alkyl group may be: M is H, a metal atom, or NR 1 4, and may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 1 4, which may be H, Na, K, Li, or NH4. 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: The fluorine-containing surfactant may be a mixture of these compounds. F(CF2)7COOM, F(CF2)5COOM, CF3O(CF2)3OCHFCF2COOM, C3F7OCF(CF3)CF2OCF(CF3)COOM, CF3CF2CF2OCF(CF3)COOM, CF3CF2OCF2CF2OCF2COOM, C2F5OCF(CF3)CF2OCF(CF3)COOM, CF3OCF(CF3)CF2OCF(CF3)COOM, CF2ClCF2CF2OCF(CF3)CF2OCF2COOM, CF2ClCF2CF2OCF2CF(CF3)OCF2COOM, CF2ClCF(CF3)OCF(CF3)CF2OCF2COOM, CF2ClCF(CF3)OCF2CF(CF3)OCF2COOM, and [ka] (In each formula, M is H, metal atom, NR 14. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. 1 is H or an organic group. The polymer compositions of the present disclosure are 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, and may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 1 4, which may be H, Na, K, Li, or NH4. R 1 is H or C 1-10 may be an organic group of H or C 1-4 may be an organic group of H or C 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 compounds is 25 ppb by mass 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: [C n-1 F 2n-1 COO - ]M + (wherein n is an integer of 9 to 14, preferably an integer of 9 to 12; M + represents a cation. 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 cation M in the above formula + The M constituting the above is the same as M described above. "Substantially free of the fluorine-containing compound represented by the above formula" means that the amount of the fluorine-containing compound is 25 ppb by mass 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.

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

[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 the temperatures corresponding to the respective minimum points in 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, and 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 a value measured by the following method. Approximately 10 mg of polymer composition that has not been heated to temperatures above 300°C is accurately weighed, placed in a dedicated aluminum pan, and measured using a TG / DTA (thermogravimetric and differential thermal 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 measuring the temperature at which a 0.1% mass loss occurs.

[0210] The polymer composition of the present disclosure also preferably has a 1.0% mass loss temperature of 370°C or higher. The 1.0% mass loss temperature within the above range indicates that the polymer composition contains a perfluoropolymer such as PFA or FEP as the 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 is preferably 492°C or lower. The 1.0% mass loss temperature is a value measured by the following method. Approximately 10 mg of polymer composition that has not been heated to temperatures above 300°C is accurately weighed, placed in a dedicated aluminum pan, and measured using a TG / DTA (thermogravimetric and 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 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 above average aspect ratio is determined by spreading the polymer composition powder thinly on a black paper surface with air without applying shear to the polymer composition, observing the polymer composition under an electron microscope, processing the images of 100 or more randomly selected particles, and averaging the ratio of their major axis to their 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 diameter 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 a powder, since it can be mixed with the electrode active material and solid electrolyte without using a large amount of dispersion medium. The TFE polymer composition may be in a form other than a powder, for example, a dispersion or a molded product.

[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 step (A) of mixing an aqueous dispersion of a fibrillating polymer with an aqueous dispersion or powder of a thermoplastic polymer, step (B) of coagulating the aqueous dispersion after mixing to obtain a wet powder, and step (C) of 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 polymerizing necessary monomers in an aqueous medium in the presence of a hydrocarbon surfactant. Hereinafter, a method for producing an aqueous dispersion in the case where 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. The sulfonic acid hydrocarbon surfactant is not limited as long as it has a -SO3H group, an -OSO3H group, or a group in which the hydrogen atom of these groups is substituted with an inorganic cation (e.g., a metal atom, ammonium, etc.). For example, from among the specific hydrocarbon surfactants and other compounds having surface activity described below, a hydrocarbon surfactant having a -SO3H group, an -OSO3H group, or a group in which the hydrogen atom of these groups is substituted with an inorganic cation can be used.

[0221] The hydrocarbon surfactant is preferably water-soluble in order to improve 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 ppm by mass or more. The maximum concentration in water is preferably 500 ppm by mass or more, more preferably 1000 ppm by mass or more, even more preferably 2000 ppm by mass or more, even more preferably 3000 ppm by mass or more, even more preferably 5000 ppm by mass or more, even more preferably 1% by mass or more, even more preferably 3% by mass or more, even more preferably 5% by mass or more, particularly preferably 10% by mass or more, and may be 50% by 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 involve adding deionized water and a hydrocarbon surfactant to a reactor, sealing the reactor, replacing the system with nitrogen, heating and pressurizing the reactor, adding a polymerization initiator, stirring for a certain period of time, and then depressurizing the reactor to atmospheric pressure and cooling. The oxidation treatment is a treatment in which an oxidizing agent is added to a hydrocarbon surfactant having one or more carbonyl groups (excluding carbonyl groups in carboxy groups). Examples of oxidizing agents include oxygen, ozone, hydrogen peroxide, manganese (IV) oxide, potassium permanganate, potassium dichromate, nitric acid, and sulfur dioxide. The production method described above makes it possible to produce a TFE polymer having a molecular weight equivalent to that of a production method using a conventional fluorine-containing surfactant, without using a conventional fluorine-containing surfactant.

[0224] In the above production method, the step of continuously adding the specific hydrocarbon surfactant preferably starts adding the hydrocarbon surfactant to the aqueous medium when the solid content of the TFE polymer formed in the aqueous medium is less than 0.60% by mass. It is preferable to start adding the specific hydrocarbon surfactant to the aqueous medium when it is 0.5% by mass or less. It is more preferable to start adding the specific hydrocarbon surfactant when the solid content is 0.3% by mass or less, even more preferably when it is 0.2% by mass or less, even more preferably when it is 0.1% by mass or less, and it is particularly preferable to start adding it at the start of polymerization. The solid content is the concentration relative to the total of the aqueous medium and the 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 a process for emulsion polymerization of tetrafluoroethylene alone or 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, preferably 0.0001 to 10% by mass relative to 100% by mass of the aqueous medium. A more preferred lower limit is 0.001% by mass, and a more preferred upper limit is 1% by mass. If the amount is less than 0.0001% by mass, the dispersion force may be insufficient, while if the amount exceeds 10% by mass, the effect commensurate with the amount may not be obtained, and instead, the polymerization rate may decrease or the reaction may stop. The amount of the specific hydrocarbon surfactant is determined appropriately depending on the type of monomer used, the molecular weight of the target TFE polymer, and other factors.

[0227] The specific hydrocarbon surfactants include those represented by the formula: RX (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 -OSOX 1 , -COOX 1 or -SO3X 1 (X 1 is H, metal atom, NR 1 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 1 are 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 a surfactant represented by the following formula (a): [ka] (In the formula, R 1a R is a linear or branched alkyl group having 1 or more carbon atoms or a cyclic alkyl group having 3 or more carbon atoms, in which a hydrogen atom bonded to a carbon atom may be substituted with a monovalent organic group containing a hydroxy group or an ester bond (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 R is independently a single bond or a divalent linking group. 1a , R 2a and R 3a X has a total of 6 or more carbon atoms. a is H, metal atom, NR 4a 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 4aR is H or an organic group (preferably an organic group not containing fluorine), and may be the same or different. 1a , R 2a and R 3a Any two of these may be bonded to each other to form a ring.) A surfactant (a) represented by the following formula (b): [ka] (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 is H, metal atom, NR 5b 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein R 5b R is H or an organic group (preferably an organic group not containing fluorine), and may be the same or different. 1b , R 2b , R 3b and R 4b Any two of may be bonded to each other to form a ring. L is a single bond, -CO2-B-*, -OCO-B-*, -CONR 6b -B-*, -NR 6b CO-B-* or -CO- (However, -CO2-B-, -OCO-B-, -CONR 6b -B-, -NR 6 The carbonyl group contained in CO-B- is excluded.) B is a single bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent, and R 6b represents H or an alkyl group having 1 to 4 carbon atoms which may have a substituent. * represents -OSO3X in the formula. b(b) a surfactant represented by the following formula (c): [ka] (In the formula, R 1c R is a linear or branched alkyl group having 1 or more carbon atoms or a cyclic alkyl group having 3 or more carbon atoms, in which a hydrogen atom bonded to a carbon atom may be substituted with a monovalent organic group containing a hydroxy group or an ester bond (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 R is independently a single bond or a divalent linking group. 1c , R 2c and R 3c A has a total of 5 or more carbon atoms. c -COOX c or -SO3X c (X c is H, metal atom, NR 4c 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein 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 these may be bonded to each other to form a ring.) A surfactant (c) represented by the following formula (d): [ka] (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. 3dis 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 -SO3X d or -COOX d (X d is H, metal atom, NR 5d 4. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein 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 may be bonded to each other to form a ring. L is a single bond, -CO2-B-*, -OCO-B-*, -CONR 6d -B-*, -NR 6d CO-B-* or -CO- (However, -CO2-B-, -OCO-B-, -CONR 6d -B-, -NR 6d The carbonyl group contained in CO-B- is excluded.) 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. * represents A in the formula. d and a surfactant (d) represented by the following formula (e): [ka] (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 has the general formula: -Y e -R 6e a group represented by R 2e and R 5e At least one of the groups has the general formula: -X e -A e or a group represented by the general formula: -Y e -R 6erepresents a group represented by the following formula: Also, X e is the same or different in each occurrence and is a divalent linking group or bond; A e may be the same or different in each occurrence, -COOM e , -SO3M e or -OSO3M e (M e is H, metal atom, NR 7e 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 7e is H or an organic group (preferably a fluorine-free organic group); Y e are the same or different in each occurrence, and are -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 are the same or different in each occurrence and each 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; Represents. R 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 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 (for example, 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 above-mentioned carboxylic acid type hydrocarbon surfactant, the ratio 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).

[0234] The carboxylic acid type hydrocarbon surfactant is preferably at least one selected from the group consisting of surfactants (c) represented by the above formula (c) and surfactants (d) represented by the above formula (d), which have 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.).

[0235] It is also preferable that the specific hydrocarbon surfactant is a sulfonic acid hydrocarbon surfactant. The sulfonic acid hydrocarbon surfactant is not limited as long as it has a -SO3H group, a -OSO3H group, or a group in which the hydrogen atom of these groups is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.). For example, from the specific hydrocarbon surfactants described above, a hydrocarbon surfactant having a -SO3H group, a -OSO3H group, or a group in which the hydrogen atom of these groups is substituted with an inorganic cation can be used. In the sulfonic acid type hydrocarbon surfactant, the ratio 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 efficiently produced by using at least one of the specific hydrocarbon surfactants. The polymer composition of the present disclosure may also be produced by simultaneously using two or more of the specific hydrocarbon surfactants, or may also be produced by simultaneously using a compound having surface activity other than the specific hydrocarbon surfactants, as long as it is volatile or may remain in a molded product made of a TFE polymer.

[0237] As the other compounds having surface activity, for example, those described in JP-A Nos. 2013-542308, 2013-542309, and 2013-542310 can be used.

[0238] Other surface-active compounds may be surfactants having a hydrophilic portion and a hydrophobic portion on the same molecule, such as hydrocarbon surfactants (excluding the above-mentioned specific hydrocarbon surfactants), which may be cationic, nonionic, or anionic. In the above compound, the ratio 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).

[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 at all).

[0240] Anionic surfactants typically have a hydrophilic portion, such as a carboxylate, sulfonate, or sulfate, and a hydrophobic portion, which is a long chain hydrocarbon moiety, such as an alkyl. In the anionic 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).

[0241] Nonionic surfactants typically contain no charged groups and have a hydrophobic portion that is a long hydrocarbon chain. The hydrophilic portion of the nonionic surfactant contains water-soluble functional groups, such as ethylene ether chains 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 at all).

[0242] Other compounds having surface activity include RLM (wherein R is a linear or branched alkyl group having one or more carbon atoms which may have a substituent, or a cyclic alkyl group having three or more carbon atoms which may have a substituent, and when the number of carbon atoms is three or more, it may contain a monovalent or divalent heterocycle or may form a ring). L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or -COO - and M is H, a metal atom, or NR 5 4(R 5 may be the same or different and are H or an organic group (preferably an organic group not containing fluorine), an imidazolium group which may have a substituent, a pyridinium group which may have a substituent, or a phosphonium group which may have a substituent. - is an aryl sulfonate. ) 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. Specifically, CH3-(CH2) such as lauric acid n -LM (wherein n is an integer of 6 to 17, and L and M are the same as above). Mixtures in which R is an alkyl group having 12 to 16 carbon atoms and LM is sulfate or sodium dodecyl sulfate (SDS) can also be used. Other surfactant compounds include R 6 (-LM)2(wherein, R 6 is a linear or branched alkylene group having one or more carbon atoms which may have a substituent, or a cyclic alkylene group having three or more carbon atoms which may have a substituent, and when the number of carbon atoms is three or more, it may contain a monovalent or divalent heterocycle or may form a ring. - , -SO3 - , -SO4-, -PO3 - or -COO - and M is H, a metal atom, or NR 54. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group (preferably an organic group not containing fluorine), -ArSO3 - is an aryl sulfonate. ) Other surfactant compounds include R 7 (-LM)3(wherein, R 7 is a linear or branched alkylidyne group having one or more carbon atoms which may have a substituent, or a cyclic alkylidyne group having three or more carbon atoms which may have a substituent, and when the number of carbon atoms is three or more, it may contain a monovalent or divalent heterocycle or may form a ring. - , -SO3 - , -SO4-, -PO3 - or -COO - and M is H, a metal atom, or NR 5 4. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group (preferably an organic group that does not contain fluorine). - is an aryl sulfonate. )

[0243] 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, where the substituents on the silicone atom are entirely hydrocarbon. These siloxane surfactants can also be considered hydrocarbon surfactants in the sense that the carbon atoms of the hydrocarbyl groups are fully substituted by hydrogen atoms, which may be substituted by halogens such as fluorine, i.e., the monovalent substituents on the carbon atoms of the hydrocarbyl groups are hydrogen. In the above siloxane 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).

[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): R 100 -COOM (α) (In the formula, 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. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein 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. From the viewpoint of surfactant activity, R 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 is preferably 29 or less, and more preferably 23 or less. The metal atom of M includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K, or Li. M may be H, a metal atom, or NR 101 4 is preferred, H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 101 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, Na, K or NH4 is even more preferred, Na or NH4 is particularly preferred, and NH4 is most preferred.

[0247] The compound (α) includes R 102 -COOM(in the formula, R 102 is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms which may have a substituent, and these may contain an ether bond. When the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. M is the same as above.) Specifically, CH3-(CH2) n -COOM (wherein n is an integer of 2 to 28, and M is the same as above).

[0248] The anionic hydrocarbon surfactant also includes, for example, a surfactant represented by the following formula (β): R 100 -SO3M (β) (In the formula, 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 1014. An optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium, wherein 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. From the viewpoint of surfactant activity, R 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 is preferably 29 or less, and more preferably 23 or less. The metal atom of M includes alkali metals (Group 1) and alkaline earth metals (Group 2), and is preferably Na, K, or Li. M may be H, a metal atom, or NR 101 4 is preferred, H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 101 4 is more preferred, H, Na, K, Li or NH4 is even more preferred, Na, K or NH4 is even more preferred, Na or NH4 is particularly preferred, and NH4 is most preferred.

[0249] The compound (β) includes R 102 -SO3M (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 number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocycle or may form a ring. M is the same as above.) Specifically, CH3-(CH2) n -SO3M (wherein n is an integer of 2 to 28, and M is the same as above) are exemplified.

[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; the percentage of the total of CH groups relative to the total of CH, CH, and CH groups in the one or more aliphatic groups is at least about 70%, and the hydrophobic moiety does not contain 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 counter ions of the ionic hydrophilic moiety; and n is 1 to 3.)

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

[0252] Compound I has the formula: [ka] (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: [ka] (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’’’ the percentage of the total of CH3 groups to the total of CH3, CH2 and CH groups in the group is at least about 70%, or 2’ and R 2’’’may be linked together to form a saturated or unsaturated aliphatic ring which may contain ether or ester linkages, provided that the percentage of the total CH3 groups relative to the total CH3, CH2 and CH groups in the ring 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. [ka] Y in the above formula + may be hydrogen, ammonium, or an alkali metal.

[0255] Compound I has the following formula III: [ka] (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’’ The percentage of the total of CH3 groups relative to the total of CH3, CH2, and CH groups in the R 3 , R 4’ , and R 4’’ At least one of the groups is not hydrogen, and R 4’ and R 4’’ is hydrogen, R 3 is not hydrogen, but R 3 is hydrogen, R 4’ and R 4’’ is not hydrogen. Y + 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. [ka] Y in the above formula + may be hydrogen, ammonium, or an alkali metal.

[0257] Even when the above-mentioned specific hydrocarbon surfactant is not used, the polymer composition of the present disclosure can be obtained by a production method including a polymerization step of polymerizing tetrafluoroethylene alone, or tetrafluoroethylene and the above-mentioned modified monomer copolymerizable with tetrafluoroethylene, in an aqueous medium having a pH of 4.0 or higher in the presence of a hydrocarbon surfactant and a polymerization initiator to obtain a TFE-based polymer. Conventionally, an acidic polymerization initiator has been used in the polymerization process for producing a TFE-based polymer, and therefore the pH of the aqueous medium used in the polymerization has been less than 4.0. As a result of intensive studies by the present inventors, it has been unexpectedly found that the stability of the polymerization can be improved by adjusting the pH of the aqueous medium used in the polymerization to 4.0 or more, and a TFE-based polymer with a high molecular weight can be produced. In the above production method, tetrafluoroethylene alone, or tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene, are polymerized in an aqueous medium having a pH of 4.0 or higher. 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, especially 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 above-mentioned specific hydrocarbon surfactant, it can also be obtained by a process that includes a polymerization step of obtaining a TFE polymer by polymerizing tetrafluoroethylene alone or tetrafluoroethylene and the modified monomer copolymerizable with the above-mentioned tetrafluoroethylene in an aqueous medium in the presence of an anionic hydrocarbon surfactant and a polymerization initiator, and the hydrocarbon surfactant contains the salt of the hydrocarbon surfactant.In other words, at least a part of the anionic hydrocarbon surfactant in the polymerization step is in the form of a salt. As a result of intensive studies, the present inventors have unexpectedly found that when an anionic hydrocarbon surfactant contains a salt of the anionic hydrocarbon surfactant, the stability of polymerization is improved and a TFE polymer having 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 for the surfactant to exhibit emulsifying properties. The anionic hydrocarbon surfactants will be described later. Whether the anionic hydrocarbon surfactant contains a salt of the hydrocarbon surfactant can be confirmed by measuring the electrical 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 preferably a carboxylic acid-type hydrocarbon surfactant, and the hydrocarbon surfactant does not contain fluorine. In the salts of anionic hydrocarbon surfactants, the cations (excluding hydrogen atoms) that replace the hydrogen atoms of the acid are, for example, metal atoms, NR y 4(R ymay be the same or different and each represents H or an organic group (preferably an organic group not containing fluorine), an imidazolium group which may have a substituent, a pyridinium group which may have a substituent, or a phosphonium group 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, NR y 4 is more preferred, and NH4 is even more preferred. Since conductivity is greatly affected by temperature, a thermostatic bath is used to keep the sample liquid temperature at 25°C, and the pH meter cell temperature is also kept at the same level 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 restart after addition or chain transfer to a free radical in the polymerization system. Specifically, a compound that easily undergoes a chain transfer reaction with a primary radical or a propagating radical to generate a stable radical that does not subsequently react with the monomer, or a compound that easily undergoes an addition reaction with a primary radical or a propagating radical to generate a stable radical, is used. Generally, the activity of what is called a chain transfer agent is characterized by the chain transfer constant and the reinitiation efficiency, but among chain transfer agents, those with a reinitiation efficiency of almost 0% are called radical scavengers. The radical scavenger can also be described as a compound whose chain transfer constant with TFE at the polymerization temperature is greater than the polymerization rate constant and whose reinitiation efficiency is substantially zero percent. "Reinitiation efficiency is substantially zero percent" means that the generated radicals turn the radical scavenger into stable radicals. Preferably, the compound has a chain transfer constant (Cs) with TFE at the polymerization temperature (=chain transfer rate constant (kc) / polymerization rate constant (kp)) of more than 0.1, and the compound has a chain transfer constant (Cs) of 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] The radical scavenger in the present disclosure is preferably at least one selected from the group consisting of, for example, aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxyamine, quinone compounds, terpenes, thiocyanates, and cupric chloride (CuCl). Examples of aromatic hydroxy compounds include unsubstituted phenol, polyhydric phenol, salicylic acid, m- or p-salicylic acid, gallic acid, and naphthol. Examples of the unsubstituted phenol include o-, m-, or p-nitrophenol, o-, m-, or p-aminophenol, p-nitrosophenol, etc. Examples of the polyhydric phenol include catechol, resorcinol, hydroquinone, pyrogallol, phloroglucinol, naphthresorcinol, etc. Examples of aromatic amines include o-, m-, or p-phenylenediamine, benzidine, and the like. Examples of the quinone compound include o-, m-, or p-benzoquinone, 1,4-naphthoquinone, and alizarin. Examples of thiocyanates include ammonium thiocyanate (NH4SCN), potassium thiocyanate (KSCN), and sodium thiocyanate (NaSCN). Of the above radical scavengers, aromatic hydroxy compounds are preferred, unsubstituted phenols or polyhydric phenols are more preferred, and hydroquinone is even more preferred.

[0262] The amount of radical scavenger added is preferably an amount equivalent to 3 to 500% (molar basis) of the polymerization initiator concentration, from the viewpoint of reducing 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 15% (molar basis), especially 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 preferably 100% (molar basis).

[0263] The polymerization initiator decomposer may be any compound capable of decomposing the polymerization initiator used, and is preferably at least one selected from the group consisting of sulfites, bisulfites, bromates, diimines, diimine salts, oxalic acid, oxalates, copper salts, and iron salts. Examples of sulfites include sodium sulfite and ammonium sulfite. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate. The amount of the polymerization initiator decomposer added is in the range of 25 to 300% by mass, preferably 25 to 150% by mass, and more preferably 50 to 100% by mass, based on the amount of the oxidizing agent combined as the polymerization initiator (redox initiator described below). The amount of decomposer for the polymerization initiator added is preferably an amount corresponding to 3 to 500% (molar basis) of the polymerization initiator concentration, from the viewpoint of reducing 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), and 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 a radical scavenger and a decomposer of a polymerization initiator is preferably added when the concentration of the TFE polymer formed in the aqueous medium is 5% by mass or more, more preferably 10% by mass or more. It is also preferable to add the TFE polymer when the concentration of the TFE 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 adding step may be a step of continuously adding at least one selected from the group consisting of a radical scavenger and a decomposer for a polymerization initiator. Continuously adding at least one selected from the group consisting of radical scavengers and decomposers for polymerization initiators means, for example, adding at least one selected from the group consisting of radical scavengers and decomposers for polymerization initiators 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] The nucleating agent is preferably at least one selected from the group consisting of, for example, fluoropolyethers, nonionic surfactants, and chain transfer agents. In this case, the polymerization step is preferably a step of obtaining a TFE-based polymer by polymerizing tetrafluoroethylene in an aqueous medium in the presence of a hydrocarbon surfactant and the nucleating agent.

[0268] The fluoropolyether is preferably a perfluoropolyether.

[0269] The above fluoropolyether preferably has repeating units represented by formulas (1a) to (1d). (-CFCF3-CF2-O-) n (1a) (-CF2-CF2-CF2-O-)n (1b) (-CF2-CF2-O-) n -(-CF2-O-) m (1c) (-CF2-CFCF3-O-) n -(-CF2-O-) m (1d) (In formulas (1a) to (1d), m and n are integers of 1 or more.)

[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 oxygen atoms in the main chain of the molecule are separated by saturated fluorocarbon groups having 1 to 3 carbon atoms. Two or more types of fluorocarbon groups can be present in the molecule.

[0272] The fluoropolyether acid or salt thereof is selected from the group consisting of fluoropolyether acids and fluoropolyether salts having the following formula: CF3-CF2-CF2-O(-CFCF3-CF2-O-) n CFCF3-COOH, CF3-CF2-CF2-O(-CF2-CF2-CF2-O-) n -CF2-CF2COOH, or HOOC-CF2-O(-CF2-CF2-O-) n -(-CF2-O-) m CF2COOH (wherein m and n are the same as above.) or a salt thereof.

[0273] These structures are discussed by Kasai in J. Appl. Polymer Sci., 57, 797 (1995). As disclosed therein, such fluoropolyethers can have carboxylic acid groups or salts thereof at one or both ends. Similarly, such fluoropolyethers can have sulfonic or phosphonic acid groups or salts thereof at one or both ends. In addition, fluoropolyethers with acid functional groups at both ends can have different groups at each end. For monofunctional fluoropolyethers, the other end of the molecule is usually perfluorinated, but may contain hydrogen or chlorine atoms.

[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] The nonionic surfactant as the nucleating agent may be any of the nonionic surfactants described above, and is preferably a nonionic surfactant that does not contain fluorine. For example, the nonionic surfactant may be a nonionic surfactant represented by the following general formula (i): R 3 -OA 1 -H(i) (In the formula, R 3 is a linear or branched primary or secondary alkyl group having 8 to 18 carbon atoms, and A 1 is a polyoxyalkylene chain. R 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 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. The polyoxyalkylene chain has 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, which is typically provided, or a broader or bimodal distribution obtained by blending. When the average repeat number of oxypropylene groups is greater than 0, the oxyethylene and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block or random configuration. From the viewpoint of viscosity and stability of the aqueous dispersion, a polyoxyalkylene chain having an average repeat number of 7 to 12 oxyethylene groups and an average repeat number of 0 to 2 oxypropylene groups is preferred. 1 If the oxypropylene group has an average of 0.5 to 1.5, low foaming properties are favorable and it is preferable.

[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-(C2H4O) 10 -H, C 12 H 25 -O-(C2H4O) 10 -H, C 10 H 21 CH(CH3)CH2-O-(C2H4O)9-H, C 13 H 27 -O-(C2H4O)9-(CH(CH3)CH2O)-H, C 16 H 33 -O-(C2H4O) 10 -H, HC(CH 11 )(C7H 15)-O-(C2H4O)9-H, etc. 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 Chemical) such as Leocol TD-90 (trade name), the Lionol (registered trademark) TD series (manufactured by Lion Chemical), 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 Chemical).

[0281] The nonionic surfactant is preferably an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 4 to about 18 ethylene oxide units, an ethoxylate of 2,6,8-trimethyl-4-nonanol having an average of about 6 to about 12 ethylene oxide units, or a mixture thereof. Nonionic surfactants of this type are also commercially available, for example, as TERGITOL TMN-6, TERGITOL TMN-10, and TERGITOL TMN-100X (all product names, manufactured by Dow Chemical).

[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, the polyoxyethylene alkylphenyl ether-based nonionic compound may be, for example, a compound represented by the following general formula (ii): R 4 -C6H4-OA 2 -H (ii) (In the formula, R 4 is a linear or branched primary or secondary alkyl group having 4 to 12 carbon atoms, and A 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 Co.).

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

[0286] The amount of the stabilizing aid used is preferably 0.1 to 12 mass % based on the mass of the aqueous medium used, and more preferably 0.1 to 8 mass %. 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 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, the polymerization temperature 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 more, and even more preferably 0.5 MPaG or more. The polymerization pressure is more preferably 5.0 MPaG or less, and even more preferably 3.0 MPaG or less. In particular, from the viewpoint of improving yield, the pressure is preferably 1.0 MPaG or higher, more preferably 1.2 MPaG or higher, even more preferably 1.5 MPaG or higher, still 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% by mass. More preferably, the concentration is 0.50% by mass or less, even more preferably 0.36% by mass or less, even more preferably 0.30% by mass or less, particularly preferably 0.20% by mass or less, and particularly preferably 0.10% by mass or less, and it is most preferable to add the surfactant at the start of polymerization. The above concentration is the concentration relative to the total of the aqueous medium and the TFE polymer. Furthermore, in the emulsion polymerization, the amount of hydrocarbon surfactant at the start of polymerization is preferably 1 ppm or more relative to the aqueous medium. The amount of 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. There is no particular upper limit, but for example, it is preferably 100,000 ppm, and more preferably 50,000 ppm. By keeping 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 within the polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, polymerization can also be initiated as a redox reaction in combination with a reducing agent or the like. The concentration of the polymerization initiator is determined appropriately depending on the type of monomer, the molecular weight of the target TFE-based polymer, and the 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 di-sec-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 sulfites or sulfites 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 low temperatures below 30°C, it is preferable to use a redox initiator, which combines an oxidizing agent and a reducing agent, as the polymerization initiator. Examples of oxidizing agents include persulfates, organic peroxides, potassium permanganate, manganese triacetate, cerium ammonium nitrate, and bromates. Examples of reducing agents include sulfites, bisulfites, bromates, diimines, and oxalic acid. Examples of persulfates include ammonium persulfate and potassium persulfate. Examples of sulfites include sodium sulfite and ammonium sulfite. To increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the redox initiator combination. Examples of copper salts include copper(II) sulfate, and examples of iron salts include iron(II) sulfate.

[0295] As the redox initiator, it is preferred that the oxidizing agent is permanganic acid or a salt thereof, a persulfate, manganese triacetate, a cerium (IV) salt, or bromic acid or a salt thereof, and the reducing agent is a dicarboxylic acid or a salt thereof, or a diimine. More preferably, the oxidizing agent is permanganic acid or a salt thereof, persulfate, or 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 of 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 a redox initiator is used, either the oxidizing agent or the reducing agent may be charged into a polymerization vessel in advance, and then the other may be added continuously or intermittently to initiate polymerization. For example, when potassium permanganate / ammonium oxalate is used, it is preferable to charge ammonium oxalate into a polymerization vessel and then continuously add potassium permanganate thereto. In this specification, when the redox initiator is described as "potassium permanganate / ammonium oxalate," it means 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 that can adjust the pH of the redox initiator aqueous solution to 4.0 or higher. The redox initiator aqueous solution refers to an aqueous solution of an oxidizing agent at a concentration of 0.50% by mass or an aqueous solution of a reducing agent at a concentration of 0.50% by mass. That is, it is sufficient that the pH of at least one of the 0.50 mass % aqueous solution of the oxidizing agent and the 0.50 mass % aqueous solution of the reducing agent is 4.0 or higher, and it is preferable that the pH of both the 0.50 mass % aqueous solution of the oxidizing agent and the 0.50 mass % aqueous solution of the reducing agent is 4.0 or higher. The pH of the redox initiator aqueous solution (0.50 mass % aqueous solution of oxidizing agent or 0.50 mass % aqueous solution of reducing agent) is more preferably 5.0 or higher, further preferably 5.5 or higher, and particularly preferably 6.0 or higher.

[0297] The redox initiator is particularly 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 the salt is more preferably at least one selected from the group consisting of persulfates, permanganates, cerium (IV) salts, and bromates, further preferably permanganates, and particularly preferably potassium permanganate. Furthermore, the reducing agent which is the salt is more preferably at least one selected from the group consisting of oxalate, malonate, succinate, glutarate and bromate, further preferably oxalate, 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, which in turn reduces the SSG and makes the polymer stretchable. Furthermore, by using a redox initiator in the polymerization step, it is possible to increase the number of TFE polymer particles produced in the aqueous dispersion, and also to increase the yield of the TFE polymer. When a redox initiator is used, the oxidizing agent and the reducing agent may be added all at once at the beginning of the polymerization, or the reducing agent may be added all at once at the beginning of the polymerization and the oxidizing agent may be added continuously, or the oxidizing agent may be added all at once at the beginning of the 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 the polymerization initiator, the amount of the oxidizing agent added is preferably 5 to 10,000 ppm, more preferably 10 to 1,000 ppm, and the amount of the reducing agent added is preferably 5 to 10,000 ppm, more preferably 10 to 1,000 ppm, relative to the aqueous medium. 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, incrementally, or continuously at the beginning of polymerization in an amount (e.g., several ppm relative to the water concentration) that does not significantly decrease the polymerization rate. The upper limit is a range in which the reaction temperature can be increased while removing heat from the equipment using the heat of polymerization reaction, and a more preferred upper limit is a range in which the heat of polymerization reaction can be removed from the equipment. 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, ether, or 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. Polymerization methods using bromine compounds or iodine compounds include, for example, a method of polymerizing fluoromonomers in an aqueous medium in the presence of a bromine compound or an iodine compound in a substantially oxygen-free state (iodine transfer polymerization method). Representative examples of the bromine compounds or iodine compounds used include, for example, compounds represented by the general formula: R a Ix 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, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, and BrCF2CFCl. Br, CFBrClCFClBr, BrCFCFCFBr, BrCFCFBrOCF, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo-substituted benzene, diiodomonobromo-substituted benzene, and (2-iodoethyl) and (2-bromoethyl) substituted benzenes. These compounds may be used alone or in combination with each other.

[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] The emulsion polymerization can produce an aqueous dispersion of a TFE polymer. The aqueous dispersion typically contains a TFE polymer, compounds (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 is preferably 60.0% by mass or less, more preferably 50.0% by mass or less. In the above production method, the amount of adhesion is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, more preferably 1.0% by mass or less, even more preferably 0.8% by mass or less, still more preferably 0.7% by mass or less, and particularly preferably 0.6% by mass or less, based on the finally obtained TFE-based polymer.

[0310] The aqueous dispersion or powder of the thermoplastic polymer in step (A) can be produced by known methods 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 coagulation is performed on 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 10 to 20% by mass), and the pH is optionally adjusted to neutral or alkaline, followed by stirring more vigorously than during the reaction in a vessel equipped with a stirrer. The coagulation may be performed while stirring while adding a coagulant such as a water-soluble organic compound (e.g., methanol or acetone), an inorganic salt (e.g., potassium nitrate or ammonium carbonate), or an inorganic acid (e.g., hydrochloric acid, sulfuric acid, or nitric acid). The coagulation may also be performed continuously using an in-line mixer or the like.

[0312] The drying (heat treatment) in step (C) is usually carried out by using a vacuum, high frequency, hot air, or other means while the wet powder is kept in a state where it is not fluidized much, preferably kept stationary. 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, in order to more efficiently remove moisture and fluorine-containing compounds. When a vacuum is used, drying at a low temperature, for example, 60°C or higher, 70°C or higher, 80°C or higher, or 90°C or higher, is also preferred.

[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, in order to more efficiently remove 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 electric furnace with 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 electric furnace with 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 the fluorine-containing compound. 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. The container having breathable bottom and / or sides is preferably a tray (bat) having breathable bottom and / or sides, and more preferably a tray having a mesh bottom and / or sides (mesh tray). The mesh is preferably either a woven mesh or a punched metal. The mesh size is preferably 2000 μm or less (ASTM standard 10 mesh or more), more preferably 595 μm or less (30 mesh or more), even more preferably 297 μm or less (50 mesh or more), even more preferably 177 μm or less (80 mesh or more), particularly preferably 149 μm or less (100 mesh or more), and particularly preferably 74 μm or less (200 mesh or more). Also, 25 μm or more (500 mesh or less) is preferred. When the mesh is a woven net, the weaving method may be, for example, plain weave, twill weave, plain tatami weave, or twill tatami weave. When the mesh is a punched metal, the porosity is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more, and is preferably 95% or less.

[0318] In step (C), the amount of the wet powder to be placed is preferably 10 g / cm 3 in order to more efficiently remove 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 concentration 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 for 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): General formula (1):(H-(CF2) m-1 -COO) p M 1 (wherein m is 4 to 20. M 1 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), 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-(CF2) 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.

[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 contains a specific polymer composition, thereby improving the Coulombic efficiency of electrochemical devices. Furthermore, a mixture sheet can be produced even with a small amount of the binder added. Furthermore, since the mixture sheet has excellent adhesion to a substrate such as a metal foil, the mixture sheet and the substrate can be bonded together without increasing the density of the mixture layer (without compaction), and processing can be performed under a wider range of molding conditions. When the binder of the present disclosure is in powder form, it can also improve flowability. The binder of the present disclosure can be used in a dry process, eliminating the need for a large amount of a dispersion medium such as water or an organic solvent, and allowing for a wide selection of electrode active materials and solid electrolytes to be combined, which is advantageous in terms of production processes. Furthermore, it can reduce the number of processes and costs associated with the use of a dispersion medium. Furthermore, since the binder of the present disclosure has excellent binding strength with the active material and the electrolyte, 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 relative to the binder 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. It is also preferred that the binder of the present disclosure consists solely of the polymer composition.

[0331] The binder of the present disclosure is preferably substantially free of organic solvents. This allows for reduction in the steps and costs associated with the use of organic solvents. "Substantially free of organic solvents" means that the organic solvent content of 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 binders of the present disclosure are used in electrochemical devices such as batteries and capacitors. Examples of the battery 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 binder for batteries, and can be particularly suitably used as a binder for secondary batteries such as lithium ion batteries. The binders of the present disclosure may be used to fabricate electrochemical device components, preferably battery components. The binder of the present disclosure can be particularly suitably used as a binder for electrodes. 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 containing 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 the 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), and processing can be carried out 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: Formula: M a Mn 2-b M 1 b O4 (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), Formula:MNi 1-c M 2 c O2 (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 Formula:MCo 1-d M 3 d O2 (Wherein, M is at least one metal selected from the group consisting of Li, Na, and K; 0≦d≦0.5; M 3 Examples of the metal oxide include alkali metal-cobalt composite oxides (lithium-cobalt composite oxides, etc.) in which M 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, MCoO2, MMnO2, MNiO2, MMn2O4, and MNi are the most popular because they can provide high energy density and high output secondary batteries. 0.8 Co 0.15 Al 0.05 O2 or MNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 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 O2(3) (In the formula, M is at least one metal selected from the group consisting of Li, Na, and K, and M 5 represents at least one element 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, and 0≦k≦0.2.

[0340] The alkali metal-containing transition metal phosphate compound is, for example, a compound represented by the following general formula (4): M e M 4 f (PO4) g (4) (In the formula, 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 in the lithium-containing transition metal phosphate compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. Specific examples include iron phosphates such as LiFePO4, Li3Fe2(PO4)3, and LiFeP2O7, cobalt phosphates such as LiCoPO4, and lithium transition metal phosphate compounds in which a portion of the transition metal atoms constituting the main components of these compounds have been substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si. The lithium-containing transition metal phosphate compound is preferably one having 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 O2(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 MFePO4 and MNi 0.8 Co 0.2 O2, M 1.2 Fe 0.4 Mn 0.4 O2, MNi 0.5 Mn 1.5 O2, MV3O6, M2MnO3, etc. In particular, M2MnO3, MNi 0.5 Mn 1.5 A positive electrode active material such as O2 (wherein M is at least one metal selected from the group consisting of Li, Na, and K) is preferable because the crystal structure does not collapse even when the secondary battery is operated at a voltage exceeding 4.4 V or at a voltage of 4.6 V or higher. Therefore, electrochemical devices such as secondary batteries using a positive electrode material containing the above-mentioned positive electrode active material are preferable 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] As other positive electrode active materials, M2MnO3 and MM 6 O2 (where M is at least one metal selected from the group consisting of Li, Na, and K, and M 6 is a transition metal such as Co, Ni, Mn, Fe, etc.) and solid solution materials thereof can also be mentioned.

[0345] As the above solid solution material, for example, an alkali metal manganese oxide represented by the general formula M x [Mn (1-y) M 7 y O z Here, M in the formula is at least one metal selected from the group consisting of Li, Na, and K, and M 7 consists of at least one metal element other than M and Mn, and for example, contains one or more elements selected from the group consisting of Co, Ni, Fe, Ti, Mo, W, Cr, Zr, and Sn. Also, the values of x, y, and z in the formula are in the range of 1 < x < 2, 0 ≤ y < 1, and 1.5 < z < 3. Among them, a manganese-containing solid solution material in which LiNiO2 or LiCoO2 is solid-solved based on Li2MnO3 such as Li 1.2 Mn[[ID=2�]] 0.5 Co 0.14 Ni[[ID=2z]] 0.14 O2 is preferable because it can provide an alkali metal ion secondary battery having a high energy density.

[0346] In addition, it is preferable to include lithium phosphate in the positive electrode active material because the continuous charging characteristics are improved. There is no limitation on the use of lithium phosphate, but it is preferable to mix and use the above positive electrode active material and lithium phosphate. The amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass or more with respect to the total of the above positive electrode active material and lithium phosphate, and the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and still 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 particle diameter d50 of the positive electrode active material (the secondary particle diameter when primary particles aggregate 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. Below the lower limit, a high tap density product may not be obtained. Above the upper limit, lithium diffusion within the particles takes too long, resulting in problems such as reduced battery performance. Mixing two or more of the above positive electrode active materials with different median diameters d50 can further improve the packing properties during positive electrode fabrication.

[0349] The median diameter d50 is measured using a known laser diffraction / scattering particle size distribution analyzer. When using a HORIBA LA-920 as the 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 If the BET specific surface area is smaller than this range, the battery performance is likely to decrease, whereas if it is larger, it becomes difficult to increase the tap density, which may easily cause problems in processability when forming the positive electrode active material layer. The BET specific surface area is defined as a value measured by a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.) using a nitrogen-helium mixed gas precisely adjusted so that the relative pressure of nitrogen to atmospheric pressure is 0.3, after which the sample is pre-dried at 150°C for 30 minutes under a nitrogen flow, by a nitrogen adsorption BET single-point method using a gas flow method.

[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 increases, which enables faster 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 above-mentioned positive electrode active materials may be used alone, or two or more of different compositions may be used in any combination or ratio. In this case, a preferred combination is LiCoO2 and LiNi 0.33 Co 0.33 Mn 0.33 Examples of such a combination include a combination with a ternary system such as O2, a combination of LiCoO2 and LiMn2O4 or a combination in which part of the Mn has been replaced with another transition metal, or a combination of LiFePO4 and LiMn2O4.

[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 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 carbonaceous materials such as non-graphitizable carbon, silicon-containing compounds such as silicon and silicon alloys, and Li4Ti5O 12 Among them, 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 is 0.5 to 100 m 2 / g is preferred, and 1 to 20m 2 / g is more preferable. 2 If the solubility is 100m / g or more, there is no risk of the adhesiveness decreasing when processed into an electrode, which may result in a decrease in battery characteristics. 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, resulting in improved 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, 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 auxiliary. Any known conductive material can be used as the conductive additive. 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, fullerene, 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. On the other hand, 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, and 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 formless state. Specific mixing methods include mixing methods using a drum mixer, conical screw mixer, single-screw kneader, twin-screw kneader, mix muller, stirring mixer, planetary mixer, Henschel mixer, 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 will take a long time to mix, which will affect productivity. If the mixing speed is above the above range, fibrillation will proceed excessively, which may result in an electrode mixture sheet with poor strength and flexibility.

[0373] In the above step (2), forming into a bulk state refers to forming the raw material composition into a single mass. Specific methods for forming into a bulk state include extrusion molding, press molding, etc. Furthermore, the term "bulk state" 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 rods, sheets, spheres, cubes, etc.

[0374] Specific examples of the rolling method in the above 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 crushed, 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 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 so that it can be rolled 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 more 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 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.

[0380] The electrode mixture sheet is Step (a): mixing powder components (such as an electrode active material) and a binder to form an electrode mixture; Step (b): Calendaring or extrusion molding the electrode mixture to produce a sheet; Including, The mixing in step (a) is (a1) homogenizing the powder components and the binder to form a powder; (a2) mixing the powdered raw material mixture obtained in step (a1) to prepare an electrode mixture; It can also be suitably produced by a production method comprising the steps of:

[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 loose and more sensitive to mechanical shear. At temperatures above 30°C, a greater degree of fibrillation occurs.

[0382] For this reason, the homogenization in (a1) is preferably carried out at a temperature of 19°C or lower, preferably 0 to 19°C. That is, in such (a1), it is preferable to mix and homogenize while suppressing fibrillation. The subsequent mixing step (a2) is preferably carried out at a temperature of 30° C. or higher to promote fibrillation.

[0383] The above step (a2) is carried out at a temperature of preferably 30°C to 150°C, more preferably 35°C to 120°C, and even more preferably 40°C to 100°C. In one embodiment, the calendering or extrusion of step (b) above 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 the step (a) is preferably carried out while applying a shear force. Specific mixing methods include mixing using a drum mixer, conical screw mixer, single-screw kneader, twin-screw kneader, mix muller, stirring mixer, planetary mixer, Henschel mixer, high-speed mixer, etc.

[0385] The mixing conditions may be set appropriately by adjusting 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, and 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 poor strength. The step (a1) is preferably carried out with a weaker shear force than the step (a2). Furthermore, it is desirable that step (a1) be carried out 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 lubricant may be used. That is, a lubricant may be added to the powdered 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), isoparaffin 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 terms of reducing deterioration of the electrochemical device, and the water content is more preferably 500 ppm or less.

[0389] When the above 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 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 used in 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 powder electrode mixture components are dispersed using a solvent containing a binder, and then coating and drying the slurry to prepare an electrode mixture sheet. 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 drying process required, the use of solvents increases processing steps and costs. Furthermore, these solvents react with electrolytes, such as electrolytic solutions and solid electrolytes, degrading the electrolyte. Therefore, residual components during slurry preparation or after drying can cause a decrease in battery performance. Furthermore, low-polarity solvents such as heptane dissolve only a very limited number of 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. By doing so, the mixture can be formed into the shape of an electrode mixture sheet. Step (b) preferably includes: (b1) forming the electrode mixture obtained in step (a) into a bulk form; and (b2) calendering or extrusion-molding the bulk electrode mixture.

[0394] Forming into a bulk form means forming the electrode mixture into a single mass. Specific methods for forming the material into a bulk form include extrusion molding, press molding, and the like. Furthermore, the term "bulk" does not particularly specify a shape, but may refer to a state in which the material 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 the 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 in which the electrode mixture is rolled using a roll press, a calender roll, or the like.

[0396] The above 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] Then, 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 carried out is preferably 2 to 10 times, more preferably 3 to 9 times. A specific rolling method is, for example, a method in which two or more rolls are rotated and the rolled sheet is passed between them to process it into a 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 a different 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 carried out after step (d), or may be carried out repeatedly. Moreover, uniaxial or biaxial stretching may be carried out in steps (a), (b), (c), and (d). Furthermore, the sheet strength can also 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 is 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 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) and (d) are preferably carried out at 30° C. or higher, more preferably 60° C. or higher, and preferably 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 of the present disclosure (preferably an electrode mixture sheet) 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 3The 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 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 / cm 3 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 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. Of 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, and 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] 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 electrolyte solution or may be a solid secondary battery. In this specification, the solid-state secondary battery may be a secondary battery containing a solid electrolyte, and may be a semi-solid-state secondary battery containing a solid electrolyte and a liquid component as the electrolyte, or an all-solid-state secondary battery containing 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-containing solvents such as fluoroethylene carbonate, fluoroethers, and fluorinated carbonates can be used.

[0422] Examples of electrolyte salts include LiClO4, LiAsF6, LiBF4, LiPF6, LiN(SO2CF3)2, and LiN(SO2C2F5)2, and LiPF6, LiBF4, LiN(SO2CF3)2, LiN(SO2C2F5)2, or combinations thereof are particularly preferred due to their favorable cycle characteristics.

[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 secondary battery, and is also 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 in 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 Li2S-P2S5, Li2S-P2S3, Li2S-P2S3-P2S5, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, LiI-Li2S-SiS2-P2S5, Li2S-SiS2-Li4SiO4, Li2S-SiS2-Li3PO4, Li3PS4-Li4GeS4, Li 3.4 P 0.6 Si 0.4 S4, Li 3.25 P 0.25 Ge 0.76 S4, Li 4-x Ge 1-x P x S4(x=0.6~0.8), Li 4+y Ge 1-y Ga y S4(y=0.2~0.3), LiPSCl, LiCl, Li 7-x-2y PS 6-x-y Cl x (0.8≦x≦1.7, 0 <y≦-0.25x+0.5)、Li 10 SnP2S12 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 compounds include Li xa La ya TiO3 [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 ee represents 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)、Li3BO3-Li2SO4、Li2O-B2O3-P2O5、Li2O-SiO2、Li6BaLa2Ta2O 12 , LiPO (4-3 / 2w) N w (w<1), Li with LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4, La with perovskite crystal structure 0.51 Li 0.34 TiO 2.94 , La 0.55 Li 0.35 TiO3, LiTi2P3O with NASICON (sodium super ionic conductor) type crystal structure 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), Li7La3Zr2O with a garnet-type crystal structure 12 (LLZ), etc. Ceramic materials in which elements are substituted for LLZ are also known. For example, Li 6.24 La3Zr2Al 0.24 O 11.98 , Li 6.25 Al 0.25 La3Zr2O12 and Ta-substituted Li 6.6 La3Zr 1.6 Ta 0.4 O 12 , Nb-substituted Li 6.75 La3Zr 1.75 Nb 0.25 O 12 Other examples include LLZ-based ceramic materials in which at least one element, Mg (magnesium) or 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 (Li3PO4), LiPON, LiPOD, and other lithium phosphates in which some of the oxygen in the lithium phosphate is substituted with nitrogen, are also desirable. 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. Specific examples include Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2 and Li2O-Al2O3-SiO2-P2O5-TiO2.

[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 Al0.3 Ti 1.7 (PO4)3, etc.), garnet type (Li7La3Zr2O 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, such as a porous membrane of polyethylene or polypropylene, or a nonwoven fabric made of a resin such as polypropylene, or 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. [Example]

[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 diameter> Measurements were made using dynamic light scattering. An aqueous fluoropolymer dispersion was prepared with a fluoropolymer solids concentration of approximately 1.0% by mass, and measurements were made at 25°C with an ELSZ-1000S (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 polymer aqueous dispersion was dried in a blower dryer under the conditions of 150 °C for 60 minutes, and the value obtained by expressing the ratio of the mass of the heat residue to the mass of the aqueous dispersion (1 g) as a percentage was adopted.

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

[0442] <Endothermic peak temperature> For a polymer composition without a heating history at a temperature of 300 °C or higher, differential scanning calorimetry [DSC] was performed at a heating rate of 10 °C / min, and the temperature corresponding to the minimum point in the melting heat curve obtained was taken as the endothermic peak temperature. When there are two or more minimum points in one melting peak, each was taken as the endothermic peak temperature.

[0443] <Standard specific gravity (SSG)> Using a sample molded in accordance with ASTM D4895 89, it was measured by the water displacement method in accordance with ASTM D 792.

[0444] <Average aspect ratio of polymer composition (powder)> The powder of the polymer composition was thinly spread on a black paper surface with air so as not to apply shear, the polymer composition was observed with an electron microscope, image processing was performed on 100 or more randomly extracted particles, and it was determined from the average of the ratio of the major axis to the minor axis.

[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 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, using a melt indexer, the mass (g / 10 min) of the polymer flowing out per 10 minutes from a nozzle with an inner diameter of 2 mm and a length of 8 mm was measured at the measurement temperature and load determined according to the type of fluoropolymer.

[0448] <Melting point of thermoplastic polymer> The melting point was taken as the temperature corresponding to the maximum value in the melting heat curve when the second heating was carried out at a rate of 10 °C / min using a differential scanning calorimeter [DSC].

[0449] <Weight average molecular weight of VT> It was measured by gel permeation chromatography (GPC). Calculated from the data measured at 50 °C using HLC-8320GPC manufactured by Tosoh Corporation and columns (three SuperAWM-H columns connected in series) with dimethylformamide (DMF) as the solvent (reference: polystyrene).

[0450] <Average particle diameter of PVdF and VT powders> Using a laser diffraction particle size distribution measuring device (LS13 320) manufactured by Beckman Coulter, the measurement was carried out dry under a vacuum pressure of 20 mH2O, and it was determined based on the obtained particle size distribution (volume basis). The average particle diameter was assumed to be equal to the particle diameter 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 the mixture was sonicated for 60 minutes to obtain an extract. The resulting extract was then analyzed 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 known concentrations of fluorine-containing compounds, aqueous solutions with five or more levels of content were prepared. LC / MS analysis of each level of content was performed, and the relationship between the content and the area was plotted to create a calibration curve. Using this calibration curve, the area of ​​the LC / MS chromatogram of the fluorine-containing compounds in the extract was converted to the content of the fluorine-containing compounds. The lower detection limit for this measurement method is 10 ppb by mass.

[0452] [Table 1]

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

[0454] <Heat of fusion of fluoroelastomer> A differential scanning calorimeter (Hitachi Technoscience, X-DSC823e) was used to obtain a DSC curve by heating 10 mg of 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] <Fluoroelastomer glass transition temperature (Tg)> A DSC curve was obtained by heating 10 mg of a sample at a rate of 20°C / min using a differential scanning calorimeter (Hitachi Technoscience, X-DSC823e). The glass transition temperature was determined as the temperature at the intersection of the extension of the baseline before and after the second-order transition of the DSC curve and the tangent to the inflection point of the DSC curve.

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

[0457] <Moisture content> Approximately 20 g of the polymer composition was heated at 150°C for 2 hours, and the mass was measured before and after, and calculated according to the following formula: A sample was taken three times, and after calculation for each, the average 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)×100

[0458] <0.1% mass loss temperature> Approximately 10 mg of polymer composition that had not been heated above 300°C was weighed out and placed in a dedicated aluminum pan for TG-DTA (thermogravimetric and differential thermal analysis). The 0.1% mass loss temperature was determined as the temperature at which a 0.1% mass loss occurred when the aluminum pan was heated in an air atmosphere from 25°C to 600°C at a rate of 10°C / min.

[0459] <1.0% mass loss temperature> Approximately 10 mg of polymer composition that had not been heated above 300°C was weighed out and placed in a dedicated aluminum pan for TG-DTA (thermogravimetric simultaneous differential thermal analysis). The 1.0% mass loss temperature was determined as the temperature at which a 1.0 mass% weight loss occurred when the aluminum pan was heated in an air atmosphere from 25°C to 600°C at a rate of 10°C / min.

[0460] <Thermal instability index (TII)> Measurement was performed in accordance with ASTM D 4895-89.

[0461] <Content of specific compounds containing fluorine> Measurement was carried out 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 the 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 resulting 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 calculated by converting it into perfluorooctanoic acid.

[0464] Perfluorooctanoic acid calibration curve Five standard solutions of perfluorooctanoic acid in methanol 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 equation (1). A=a×X+b (1) A: Peak area of ​​perfluorooctanoic acid X: Perfluorooctanoic acid concentration (ng / mL)

[0465] Measurement equipment configuration and LC-MS measurement conditions [Table 2]

[0466] MRM measurement parameters [Table 3]

[0467] The content of the compound represented by general formula (1) having 4 to 20 carbon atoms contained in the extract A liquid chromatograph mass spectrometer was used to measure compounds represented by general formula (1) having a carbon number of 4 to 20. The peak areas of the compounds represented by general formula (1) having each carbon number were determined for the extracted liquid phase using the MRM method.

[0468] MRM measurement parameters [Table 4]

[0469] The content of the compound represented by general formula (1) with carbon number (m+1) in the extract was calculated using the following formula (3), where a and b in formula (3) were calculated from formula (1). XCm=((ACm-b) / a)×((50×m+45) / 413) (3) XCm: Content (ng / mL) of the compound represented by general formula (1) with carbon number (m+1) in the extract solution ACm: Peak area of ​​the compound represented by general formula (1) with carbon number (m+1) in the extract solution The limit of quantitation for this assay is 1 ng / mL.

[0470] The content of the compound represented by general formula (1) having the carbon number (m+1) contained in the composition The content of the compound represented by general formula (1) having the carbon number (m+1) contained in the composition was calculated by the following formula (4). Y cm = X cm × 12.6 (4) YCm: Content of the compound represented by general formula (1) with carbon number (m+1) contained in the composition (ppb vs. TFE-based polymer) The lower limit of quantification is 10 ppb by mass.

[0471] [Method for measuring the content of the compound represented by formula (2)] Extraction from the 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 resulting 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 calculated by converting it into perfluorooctanesulfonic acid.

[0473] Perfluorooctanesulfonic acid calibration curve Five standard solutions of perfluorooctanesulfonic acid in methanol 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 equation (1). A=a×X+b (1) A: Peak area of ​​perfluorooctanesulfonic acid X: Perfluorooctanesulfonic acid concentration (ng / mL)

[0474] Measurement equipment configuration and LC-MS measurement conditions [Table 5]

[0475] MRM measurement parameters [Table 6]

[0476] The content of the compound represented by general formula (2) having 4 to 20 carbon atoms contained in the extract A liquid chromatograph mass spectrometer was used to measure compounds represented by general formula (2) having a carbon number of 4 to 20. 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 [Table 7]

[0478] The content of the compound represented by general formula (2) with carbon number n in the extract was calculated using the following formula (3), where a and b in formula (3) were calculated from formula (1). XSn=((ASn-b) / a)×((50×n+81) / 499) (3) XSn: Content of the compound represented by general formula (2) with carbon number n in the extract solution (ng / mL) ASn: Peak area of ​​the compound represented by general formula (2) with carbon number n in the extract solution The limit of quantitation for this assay is 1 ng / mL.

[0479] The content of the compound represented by general formula (2) having n carbon atoms contained in the composition The content of the compound represented by general formula (2) having a carbon number n contained in the composition was calculated by the following formula (4). YSn=XSn×12.6 (4) YSn: Content of the compound represented by general formula (2) with carbon number n contained in the composition (ppb vs. TFE-based polymer) The lower limit of quantification 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 thereto 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] Manufacturing Example 1 A 3 L stainless steel reactor equipped with a stirrer was charged with 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. The pH of the aqueous dispersion 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. Continuously charging a 0.5% by mass aqueous potassium permanganate solution as a polymerization initiator into the reactor began, and the pressure decreased, initiating the reaction. TFE was charged to maintain a constant reaction pressure of 2.70 MPa. When 80 g of TFE had been charged, the stirring was stopped, and the reaction pressure was reduced to atmospheric pressure. The reactor was immediately 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 continuous addition of Aqueous Solution D obtained in Preparation Example 1 to the reactor was initiated. When 680 g of TFE had been added, 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 had been added. The aqueous dispersion was removed from the reactor, cooled, and the paraffin wax was separated to obtain an aqueous PTFE dispersion. The resulting aqueous PTFE dispersion had a pH of 8.8, a solids concentration of 27.1 mass%, and a primary particle size of 220 nm.

[0483] The resulting PTFE aqueous dispersion was diluted with deionized water to a solids concentration of 13% by mass, and the mixture was vigorously stirred in a container equipped with a stirrer to solidify, and then filtered to separate the water, yielding 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 circulating 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 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 content of the compound represented by general formula (1) having carbon number m (4 to 20) contained in the obtained PTFE powder was 67 mass ppb, and the content of the compound represented by general formula (2) having carbon number n (4 to 20) contained in the obtained PTFE powder was less than 10 mass ppb.

[0484] Manufacturing Example 2 A 6-L stainless steel reactor equipped with a stirrer was charged with 3,580 g of deionized water and 7.56 g of white solid A. The reactor contents 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 TFE addition until a pressure of 2.4 MPaG was reached. 306 mg of ammonium persulfate (APS) initiator dissolved in 20 g of deionized water was then injected into the reactor. After the initiator injection, a pressure drop occurred, indicating the initiation of polymerization. TFE was added to the reactor to maintain a constant pressure of 2.4 MPaG. After polymerization initiation, 108 mg of ammonium persulfate and 84 g of PPVE were continuously added. When approximately 1,600 g of TFE had been consumed in the reaction, the TFE supply was stopped, the stirring was stopped, and the reaction was terminated. Thereafter, the pressure inside the reactor was evacuated until it reached normal pressure, and PFA aqueous dispersion 1 was obtained. The PFA aqueous dispersion 1 was taken out from the reactor into the atmosphere and cooled to obtain a PFA aqueous dispersion 2. The solid content concentration of the obtained PFA aqueous dispersion 2 was 30.5% by mass. The resulting PFA aqueous dispersion 2 was stirred, coagulated and dried to obtain a PFA powder. The resulting PFA powder had a PPVE content of 6.5 mass %, an MFR of 2.1 g / 10 min, and a melting point of 295°C.

[0485] Manufacturing Example 3 A 1000 L stainless steel reactor equipped with a stirrer was charged with 655 L of deionized water and 6 kg of white solid A. The contents were then subjected to nitrogen substitution and vacuum degassing to remove oxygen from the reactor and agitation. Subsequently, 100 kg of HFP monomer was charged, followed by a mixed monomer of TFE and HFP (TFE:HFP = 86:14 (wt%)). The temperature was increased with stirring to 95°C and the pressure was increased to 1.5 MPaG. 70 kg of a 10 wt% aqueous ammonium persulfate (APS) solution was charged as an initiator to initiate the reaction. The mixed monomer was continuously fed to maintain a pressure of 1.5 MPaG in the reaction system. Thirty minutes after the start of the reaction, agitation was stopped to terminate the reaction, and the gas in the reactor was released to atmospheric pressure, yielding an aqueous TFE / HFP binary polymer dispersion. The solids concentration of the resulting aqueous TFE / HFP binary polymer dispersion was 4.5 wt%.

[0486] Separately, a similar stainless steel reactor was charged with 600 L of deionized water and 20 kg of the above binary polymer emulsion dispersion. The reactor was then purged with nitrogen and vacuum degassed to remove oxygen from the reactor, and the contents were stirred. Subsequently, 138 kg of HFP monomer and 4 kg of PPVE were charged, and the temperature was increased with stirring until the reactor contents reached 95°C. A TFE and HFP monomer mixture (TFE:HFP = 87.3:12.7 (wt%)) was then added under pressure to raise the pressure to 4.2 MPaG. 2.8 kg of a 10 wt% APS aqueous solution was added as an initiator to initiate the reaction. After the reaction began, the 10 wt% APS aqueous solution was continuously added at a rate of approximately 20 g / min. During the reaction, 180 g of PPVE was added each time the amount of the monomer mixture reached 25 wt%, 50 wt%, and 75 wt% of the total monomer amount. The monomer mixture was continuously fed to maintain the pressure in the reaction system at 4.2 MPaG. 51 minutes after the start of the reaction, the addition of the 10% by weight APS aqueous solution was stopped, stirring was stopped to terminate the reaction, and the gas in the reactor was released to atmospheric pressure to obtain an aqueous FEP dispersion of TFE / HFP / PPVE. The solids concentration of the resulting aqueous FEP dispersion of TFE / HFP / PPVE was 20.2% by weight. 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 An aqueous PVdF dispersion was prepared with reference to Example 1 of JP 2014-141673 A. Specifically, 1700 g of pure water, 0.85 g of a fluorinated surfactant (H-(CFCF)-CH-O-CO-CHCH(-SONa)-CO-O-CH-(CFCF)-H) (surface tension: 22 mN / m), and 17 g of paraffin wax were placed in a 3.0 L stainless steel reactor, and the atmosphere was purged with nitrogen to remove oxygen. 150 g of vinylidene fluoride (VdF) was added, and the reactor was heated 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. To maintain the pressure in the tank at 4.0 MPaG, 427 g of vinylidene fluoride was added over 9 hours, and 1.45 g of H-(CF2CF2)3-CH2-O-CO-CH2CH(-SO3Na)-CO-O-CH2-(CF2CF2)3-H was added during the reaction to obtain an aqueous PVdF dispersion. The solid content of the resulting PVdF aqueous dispersion was 20.6% by mass. The resulting PVdF aqueous dispersion was coagulated, dried at 120°C, and pulverized to obtain PVdF powder. The melting point of PVdF was 161°C, the average particle size was 1.1 µm, and the amount of fluorine-containing surfactant was 110 ppb by mass.

[0488] Manufacturing Example 5 A 4-L reactor was charged with 1.3 kg of pure water, purged with nitrogen, and deoxygenated. Then, 0.88 kg of octafluorocyclobutane was added, and the system was heated to 37°C and stirred. A TFE / VdF = 5 / 95 mol% mixed gas was then added until the system pressure reached 1.3 MPaG. Then, 1.5 g of a 50% by mass solution of di-n-propyl peroxydicarbonate in methanol was added to initiate the reaction. As the reaction progressed, the system pressure decreased, and a TFE / VdF = 15 / 85 mol% mixed gas was continuously added 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 then pulverized in a high-speed mill to obtain 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 composition did not contain any fluorine-containing surfactant.

[0489] Manufacturing Example 6 A 3L stainless steel polymerization vessel equipped with a stirrer was charged with 1500g of deionized water, 4.8g of fluorinated surfactant (white solid A), and 0.3g of CH2=CFCF2OCF(CF3)CF2OCF(CF3)COONH4 and sealed. After purging the vessel with nitrogen, the vessel was evacuated and 400cc of isopropyl alcohol (chain transfer agent) was added via a syringe while suctioning. Then, with stirring at 70°C, a vinylidene fluoride (VdF) / tetrafluoroethylene (TFE) mixed gas monomer with a composition ratio of 67 / 33 mol% was charged to 0.8 MPaG. The reaction was then initiated by injecting an aqueous solution containing 0.15g of ammonium persulfate under nitrogen pressure. Additional VdF / TFE mixed monomer with a composition ratio of 67 / 33 mol% was added to maintain the vessel pressure. When the added monomer reached 346g, stirring was stopped and the vessel gas was released to terminate the reaction. The inside of the tank was cooled to obtain a VT aqueous dispersion, the solid content of which 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, which was then pulverized in a high-speed mill to obtain a VT powder. The average particle size of the obtained VT powder was 1.1 μm, and the amount of the fluorine-containing surfactant was 340 ppb by mass.

[0490] Manufacturing Example 7 A 3L stainless steel autoclave was charged with 1650ml of pure water and purged with nitrogen. The pressure was then slightly increased with hexafluoropropylene (HFP). The temperature was adjusted to 80°C while stirring. HFP was then added under pressure to 0.23 MPaG, followed by a vinylidene fluoride (VdF) to HFP mixture with a molar ratio of 78.2 / 21.8. The mixture was then added under pressure to 1.472 MPaG. 0.097ml of 2-methylbutane was then added under pressure with nitrogen, and a solution of 36.4g of ammonium persulfate in 80ml of pure water was added under pressure with nitrogen to initiate the reaction. When the pressure dropped to 1.44 MPaG, the pressure was increased to 1.50 MPaG with continuous monomer and maintained at that level. Approximately 9.3 hours after the start of the reaction, 607g of continuous monomer was added, and the stirring was stopped. The autoclave was vented, cooled, and 2299g of dispersion was recovered. The solid content of the resulting aqueous elastomer dispersion was 26.9% by mass. The composition of the obtained elastomer was VdF / HFP = 77.9 / 22.1 (mol%). The obtained elastomer had a Mooney viscosity (ML1+10 (140°C)) of 77, a weight-average molecular weight of 850,000, and a Tg of -18°C measured by DSC. No heat of fusion was observed in the second run.

[0491] Manufacturing Example 8 A 6-liter stainless steel reactor equipped with a stainless steel stirring blade and a temperature-control 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 and the atmosphere was purged 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 of 18.0 mg of hydroquinone dissolved in 20 g of water as a radical scavenger was injected with TFE. The polymerization continued, and when the amount of TFE polymerized reached approximately 1,200 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, terminating the polymerization reaction. The aqueous dispersion was removed and cooled, and the paraffin wax was separated to obtain an aqueous PTFE dispersion. The average primary particle size of the resulting aqueous PTFE dispersion was 310 nm, and the solids concentration was 25.3 mass%. The resulting aqueous PTFE dispersion was coagulated and dried to obtain a PTFE powder. The resulting PTFE powder had an SSG of 2.156 and an endothermic peak temperature of 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, and 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 for 12 hours at 50° C. A solution of sodium methoxide (3.8 g) in methanol (12 mL) was added dropwise to the reaction mixture. 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 surfactant aqueous solution B.

[0493] Manufacturing Example 9 A 6-L stainless steel reactor equipped with a stirrer was charged with 3600 g of deionized and degassed water, 180 g of paraffin wax, and 0.540 g of surfactant A. The reactor was then sealed, and the system was purged with nitrogen to remove oxygen. The reactor was heated to 70°C, charged with TFE, and the pressure in the reactor was adjusted to 2.70 MPa. 0.620 g of ammonium persulfate (APS) and 1.488 g of disuccinic acid peroxide (DSP) were added as polymerization initiators. TFE was added to maintain a constant reaction pressure of 2.70 MPa. Simultaneously with the start of TFE addition, surfactant aqueous solution B was continuously added. When 540 g of TFE had been added, 20 g of deionized and degassed water containing 0.76 g of hydroquinone was added. When 1200 g of TFE had been added, the stirring was stopped, and the reactor was depressurized until atmospheric pressure was reached. By the end of the reaction, 103 g of the surfactant aqueous solution B had been charged. The contents were removed from the reactor and cooled, after which the paraffin wax was separated to obtain a TFE-based polymer aqueous dispersion B. The resulting TFE-based polymer aqueous dispersion B had a solid content of 25.9 mass % and an average primary particle size of 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 the dilution was vigorously stirred in a container equipped with a stirrer to solidify the dilution, and then the water was filtered off 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 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 0.003% 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. In the obtained PTFE powder, compounds represented by general formula (1) having carbon numbers m = 15 and 16 were detected, with the content of the compound represented by general formula (1) having carbon number m = 15 being 73 ppb by mass, and the content of the compound represented by general formula (1) having carbon number m = 16 being 141 ppb by mass. In addition, compounds represented by general formula (2) having carbon numbers n = 4, 6, 8, 10, 12, and 14 were detected, with the content of the compound represented by general formula (2) having carbon number n = 8 being 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 put into container, and with deionized water dilute so that solid content concentration becomes 13% by mass, and under high speed stirring, the PTFE / PFA mixture is co-precipitated, and then filtered out with water, and 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 240°C. After 20 hours, the mesh tray was removed and air-cooled to obtain a PTFE / PFA mixed powder. The mixture ratio (mass ratio) of the obtained PTFE / PFA mixed powder was PTFE / PFA = 80 / 20. The resulting PTFE / PFA mixed powder was designated as 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 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 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 manufacturing example 1 and 297g of the FEP aqueous dispersion obtained in manufacturing example 3 are put into container, and dilute with deionized water so that solid content concentration becomes 13% by mass, and under high-speed stirring, PTFE / FEP mixture is co-precipitated, then filter out with water, and 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 circulating electric furnace at 210°C. After 20 hours, the mesh tray was removed and air-cooled to obtain a PTFE / FEP mixed powder. The mixture ratio (mass ratio) of the obtained PTFE / FEP mixed powder was PTFE / FEP = 80 / 20. The resulting PTFE / FEP mixed powder was designated as 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 moisture content of 0.000% by mass. The content of the compound represented by general formula (1) having 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 carbon number n (4 to 20) was less than 10 ppb by mass.

[0497] Preparation example 3 775g of the PTFE aqueous dispersion obtained in manufacturing example 1 and 437g of the PVdF aqueous dispersion obtained in manufacturing example 4 are put into a container, and diluted with deionized water to make the solid content concentration 13% by mass, and nitric acid is added as a coagulant to co-coagulate the PTFE / PVdF mixture while stirring, and then the water is filtered off 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 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 resulting PTFE / PVdF mixed powder was designated as polymer composition C. Polymer composition C had endothermic peak temperatures of 161°C and 342°C, and a water content of 0.003% by mass. The content of the compound represented by general formula (1) having carbon number m (4 to 20) contained in polymer composition C was 3786 mass ppb, and the content of the compound represented by general formula (2) having carbon number n (4 to 20) was less than 10 mass ppb.

[0498] Preparation example 4 Put 886g of the PTFE aqueous dispersion obtained in preparation example 1, 60g of the VT powder obtained in preparation example 5 and 960g of deionized water into a container, add nitric acid as coagulant, and while stirring, carry out co-coagulation and drying in the same manner as preparation example 3, to obtain mixed powder.The mixing ratio (mass ratio) of the obtained PTFE / VT mixed powder is PTFE / VT=80 / 20. The resulting PTFE / VT mixed powder was designated as polymer composition D. Polymer composition D had endothermic peak temperatures of 136°C and 342°C, a water content of 0.005% by mass, an average aspect ratio of 1.1, and the PTFE powder was not fibrillated. The content of the compound represented by general formula (1) having carbon number m (4 to 20) contained in polymer composition D was 4,326 mass ppb, and the content of the compound represented by general formula (2) having carbon number n (4 to 20) was less than 10 mass ppb.

[0499] Preparation example 5 Put 996g of the PTFE aqueous dispersion obtained in preparation example 1, 30g of the VT powder obtained in preparation example 6 and 1080g of deionized water into a container, add nitric acid as coagulant, and while stirring, carry out co-coagulation and drying in the same manner as in preparation example 3, to obtain mixed powder.The mixing ratio (mass ratio) of the obtained PTFE / VT mixed powder is PTFE / VT=90 / 10. The resulting PTFE / VT mixed powder was designated as polymer composition E. Polymer composition E had endothermic peak temperatures of 160°C and 342°C, a water content of 0.003 mass%, an average aspect ratio of 1.2, and the PTFE powder was not fibrillated. The content of the compound represented by general formula (1) having carbon number m (4 to 20) contained in polymer composition E was 4867 mass ppb, and the content of the compound represented by general formula (2) having carbon number n (4 to 20) was less than 10 mass ppb.

[0500] Preparation Example 6 135 g of the PTFE powder obtained in Production Example 1 and 15 g of the VT powder obtained in Production Example 6 were placed in a V-type mixer (VK-1, manufactured by Irie Shokai Co., Ltd.) and mixed at 30 rpm for 10 minutes. 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 as polymer composition F. Polymer composition F had endothermic peak temperatures of 160°C and 342°C, a water content of 0.001% by mass, an average aspect ratio of 1.5, and the PTFE powder was not fibrillated. The content of the compound represented by general formula (1) having carbon number m (4 to 20) contained in polymer composition F was 60 ppb by mass, and the content of the compound represented by general formula (2) having 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 Production Example 1 and 223 g of the elastomer aqueous dispersion obtained in Production Example 7 were placed in a container, diluted with deionized water to a solid content of 15% by mass, and nitric acid was added as a coagulant to co-coagulate the PTFE / elastomer mixture under high-speed stirring. The mixture was 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 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 resulting PTFE / elastomer mixed powder was designated as Polymer Composition G. Polymer composition G had an endothermic peak temperature of 342°C, a water content of 0.005% by mass, and an average aspect ratio of 1.1, and the PTFE powder was not fibrillated. The content of the compound represented by general formula (1) having carbon number m (4 to 20) contained in polymer composition G was 4846 mass ppb, and the content of the compound represented by general formula (2) having carbon number n (4 to 20) was less than 10 mass ppb.

[0502] Preparation Example 8 830g of the PTFE aqueous dispersion obtained in manufacturing example 8 and 437g of the PVdF aqueous dispersion obtained in manufacturing example 4 are put into a container, and diluted with deionized water to make the solid content concentration 13% by mass, and nitric acid is added as a coagulant to co-coagulate the PTFE / PVdF mixture while stirring, and then filtered out 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 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 resulting PTFE / PVdF mixed powder was designated as Polymer Composition X. Polymer composition X had endothermic peak temperatures of 161°C and 343°C, a water content of 0.003 mass%, an average aspect ratio of 1.1, and the PTFE powder was not fibrillated. Polymer composition X does not contain the compounds represented by general formulas (1) and (2) because PTFE containing no hydrocarbon surfactant was used. Therefore, the content of the compound represented by general formula (1) having carbon number m (4 to 20) contained in polymer composition X was less than 10 ppb by mass, and the content of the compound represented by general formula (2) having carbon number n (4 to 20) was less than 10 ppb by mass.

[0503] Example 9 811g of the PTFE aqueous dispersion obtained in manufacturing example 9 and 437g of the PVdF aqueous dispersion obtained in manufacturing example 4 are put into a container, and diluted with deionized water to make the solid content concentration 13% by mass, and nitric acid is added as a coagulant to co-coagulate the PTFE / PVdF mixture while stirring, and then filtered out 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 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 resulting PTFE / PVdF mixed powder was designated as polymer composition H. Polymer composition H had endothermic peak temperatures of 161°C and 344°C, and a water content of 0.004% by mass. The content of the compound represented by general formula (1) having a carbon number m of 15 contained in polymer composition H was 31,460 mass ppb, and the content of the compound represented by general formula (2) having a carbon number n of 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 electrode mixture sheets for batteries containing electrolyte The 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 heated sufficiently in a thermostatic chamber at 80°C, and then treated in a Henschel mixer at 3000 rpm for 30 minutes to promote fibrillation, thereby obtaining a mixture. The mixture was further kneaded (50 rpm, 10 minutes) in a benchtop kneader (PN-1, manufactured by Irie Shokai) to promote fibrillation, and then pulverized in a Henschel mixer at 3000 rpm for 5 minutes to promote fibrillation and improve dispersibility, yielding an electrode mixture. The electrode mixture was placed between metal rolls arranged parallel to the left and right 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 temperature: 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 to the mixture.

[0507] <Evaluation of the performance of the combination 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 judged 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] [Table 8]

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

[0510] The mixture sheets of Examples B1 to B8 and Comparative Example B1 were produced and evaluated according to the following procedures.

[0511] <Preparation of negative electrode> The negative electrode mixture sheets prepared with binder addition amounts of 2.6 mass % and 3.2 mass % were attached to a current collector. A 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 laminated 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, with 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> 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. LiPF6 salt was dissolved in this mixed solution so that the concentration in the electrolyte solution became 1.1 mol / L, and a nonaqueous electrolyte solution was obtained.

[0513] <Coin cell fabrication> 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, etc., the battery was sealed to prepare a lithium ion secondary battery.

[0514] <Evaluation of battery characteristics (coulombic efficiency)> The lithium-ion secondary battery produced above was tested at 30°C. It was charged at a constant current and constant voltage (cut off at 0.05C) to 0.01V at a current equivalent to 0.1C, and then discharged to 1.5V at a constant current of 0.1C. The initial coulombic efficiency results are shown in Table 9. Coulombic efficiency is the ratio of the discharge capacity during discharge to the charge capacity during charging, expressed as a percentage. Because the coulombic efficiency decreases due to side reactions in the battery system, batteries with high efficiency show less deterioration during the initial charging and discharging stages.

[0515] [Table 9]

[0516] The mixture sheets of Examples C1 to C8 and Comparative Example C1 were produced and evaluated according to the following procedures.

[0517] <Preparation of negative electrode> The negative electrode mixture sheet prepared with a binder addition amount of 3.2% was attached to a current collector. A 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 to produce 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, with a speed of 0.1 m / min and a pressure of 6 KN. The gap was adjusted so that the electrode mixture density was 1.30 to 1.50 g / cc. The bonded electrode sheets were then punched into round shapes using a hand punch with a diameter of 15 mm. The cut edges were observed, and samples that showed no peeling or lifting from the current collector were rated as "OK," while samples that showed peeling or lifting were rated as "NG." The results are shown in Table 10.

[0518] [Table 10] ...

Claims

[Claim 1] 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 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; and 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.

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