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

Abstract

To provide a polymer composition for a binder for an electrochemical device, which is capable of improving the coulomb efficiency of the electrochemical device.SOLUTION: A polymer composition is used for a binder for an electrochemical device and includes a fibrillation polymer, a thermoplastic polymer, and at least one kind of compound selected from the group consisting of compounds represented by General Formulae (1) and (2). General Formula (1): (H-(CF2)m-1-COO)pM1 (in which m is 4 to 20, M1 is H, a metal atom, NR54 (R5 may be either the same or different and is H or an organic base with 1 to 10 carbons), etc., and p is 1 or 2). General Formula (2): (H-(CF2)n-SO3)qM2 (in which n is 4 to 20, M2 is H, a metal atom, or NR54 (R5 is the same as above), etc., and q is 1 or 2).SELECTED DRAWING: None

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 the polymer composition according to any one of the present disclosures (1) to (6) used as a binder for a lithium ion secondary battery.

[0015] The present disclosure (8) is a binder for an electrochemical device consisting essentially of only a polymer composition, wherein the polymer composition includes a fibrillatable polymer, a thermoplastic polymer, and at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2). General formula (1): (H-(CF2) m-1 -COO) p M 1 (In the formula, m is 4 to 20. M 1 is H, a metal atom, NR 5 4 (R 5 may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF2) n -SO3) q M 2 (In the formula, n is 4 to 20. M 2 is H, a metal atom, NR 5 4 (R 5 is the same as above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. q is 1 or 2.)

[0016] The present disclosure (9) is a binder for an electrochemical device consisting essentially of only a polymer composition, wherein the polymer composition includes a fibrillatable polymer and a thermoplastic polymer, and the thermal instability index (TII) of the fibrillatable polymer is 10 or more.

[0017] The present disclosure (10) is a binder for an electrochemical device according to the present disclosure (8) or (9), wherein the polymer composition has endothermic peaks in respective regions of 330°C or lower and above 330°C.

[0018] The present disclosure (11) is a binder for an electrochemical device according to any one of the present disclosures (8) to (10), wherein the endothermic peak temperature of the fibrillatable polymer is above 330°C.

[0019] The present disclosure (12) is a binder for an electrochemical device according to any one of the present disclosures (8) to (11), wherein the fibrillatable polymer is a tetrafluoroethylene-based polymer.

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

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

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

[0023] The present disclosure (16) is a binder for an electrochemical device according to any one of the present disclosures (8) to (15), wherein the content of the fibrillatable polymer is more than 50% by mass and 97% by mass or less with respect to the polymer composition.

[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 a binder for an electrochemical device, an electrode active material, and a current collector according to any one of the present disclosures (8) to (29).

[0040] The present disclosure (33) is a secondary battery including the electrode described in the present disclosure (32).

Advantages 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 Coulomb efficiency of the electrochemical device, and a binder for an electrochemical device, an electrode binder, an electrode, and a secondary battery using the same.

Embodiments for Carrying Out the Invention

[0042] In the present disclosure, the “organic group” means a group containing one or more carbon atoms, or a group formed by removing one hydrogen atom from an organic compound. As the above organic group, an alkyl group which may have one or more substituents is preferable.

[0043] Hereinafter, the present disclosure will be specifically described.

[0044] The present disclosure is a polymer composition used for a binder for an electrochemical device, and includes a fibrillatable polymer, a thermoplastic polymer, and at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2) (hereinafter, also referred to as the polymer composition (1) of the present disclosure). General formula (1): (H-(CF2) m-1 -COO) p M 1 (In the formula, m is 4 to 20. M 1 is H, a metal atom, NR 5 4 (R 5is the same or different, and is H or an organic group having 1 to 10 carbon atoms), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF2) n -SO3) q M 2 (In the formula, n is 4 to 20. M 2 is H, a metal atom, NR 5 4 (R 5 is the same as above), 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.)

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

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

[0047] By having the above configuration, the polymer composition of the present disclosure can improve the Coulomb efficiency of an electrochemical device. In addition, a composite sheet can be produced even with a small addition amount. Further, since a composite sheet excellent in adhesion to a base material such as a metal foil can be obtained, the composite sheet and the base material can be adhered without increasing the density of the composite layer (without pressure consolidation), and can be processed under a wider molding condition.) When the polymer composition of the present disclosure is in the form of powder, the fluidity can also be improved.) Since the polymer composition of the present disclosure can also be used in a dry state, it is not necessary to use a large amount of dispersion media such as water and organic solvents, and a wide range of electrode active materials and solid electrolytes can be selected for combination, which is advantageous in the production process. In addition, the processes and costs associated with the use of dispersion media can be reduced. Furthermore, since the polymer composition of the present disclosure has excellent adhesion to active materials and electrolytes, the amount used can be reduced.

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

[0049] The above fibrillatable polymer preferably has an endothermic peak temperature exceeding 330 °C, more preferably 333 °C or higher, still 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 that it can form a composite sheet with even better strength. The above endothermic peak temperature is the temperature corresponding to the minimum point in the melting heat curve obtained by performing differential scanning calorimetry [DSC] on the fibrillatable polymer having no heating history at a temperature of 300 °C or higher at a heating rate of 10 °C / min. When there are two or more minimum points in one melting peak, each is taken as the endothermic peak temperature.

[0050] In the polymer composition (1) of the present disclosure, the fibrillating polymer preferably has a thermal instability index (TII) of 10 or more. In the polymer composition (2) of the present disclosure, the fibrillating polymer 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. The fibrillatable polymer with a 1.0% mass loss temperature of 492 °C or lower can be obtained by using a hydrocarbon-based surfactant. The above 1.0% mass loss temperature is the value measured by the following method. Weigh accurately about 10 mg of the fibrillatable polymer without a heating history at a temperature of 300 °C or higher, store it in a dedicated aluminum pan, and measure it with a TG·DTA (differential thermal and thermogravimetric simultaneous measurement device). The 1.0% mass loss temperature is the temperature corresponding to the point where the weight has decreased by 1.0 mass% when the temperature range of the aluminum pan from 25 °C to 600 °C is raised at a rate of 10 °C / min under an air atmosphere.

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

[0054] The above TFE-based polymer may be a homopolymer of TFE, or a TFE copolymer containing a polymerization unit based on TFE (TFE unit) and a polymerization unit based on a modified monomer copolymerizable with TFE (modified monomer unit). The above TFE-based polymer may be polytetrafluoroethylene (PTFE). The above PTFE includes a homopolymer of TFE and a modified PTFE containing 99.0 mass% or more of TFE units and 1.0 mass% or less of modified monomer units. The above TFE-based polymer is preferably PTFE and more preferably modified PTFE in terms of the ability to further improve the Coulomb efficiency of the electrochemical device, the ability to further reduce the addition amount, the ability to further improve the adhesion between the composite sheet and the substrate, and the ability to further improve the powder fluidity. In the present disclosure, the homopolymer of TFE refers to a polymer in which the content of the modified monomer unit with respect to all polymerization units is less than 0.0001 mass%.

[0055] The content of the modified monomer unit is preferably in the range of 0.0001 to 10% by mass relative to the total polymerized units, from the viewpoints of further improving the Coulomb efficiency of the electrochemical device, further reducing the amount added, further improving the adhesion between the composite sheet and the substrate, and further improving 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 perfluoro organic group. Examples thereof include perfluoro unsaturated compounds represented by ( ). In the present specification, the above-mentioned "perfluoro organic group" means an organic group in which all hydrogen atoms bonded to carbon atoms are substituted by fluorine atoms. The above-mentioned perfluoro organic group may have an ether oxygen.

[0059] Examples of the above-mentioned perfluorovinyl ether include perfluoro(alkyl vinyl ether) [PAVE]. Preferably, in the above general formula (A), Rf 1 is PAVE in which the perfluoroalkyl group has 1 to 10 carbon atoms. The number of carbon atoms of the above-mentioned perfluoroalkyl group is preferably 1 to 5.

[0060] Examples of the perfluoroalkyl group in the above-mentioned PAVE include a perfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group, a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group, and the like.

[0061] Examples of the above-mentioned perfluorovinyl ether further include those in which, in the above general formula (A), Rf 1 is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and Rf 1 is a group represented by the following formula:

[0062]

Chemical formula

[0063] (wherein m represents an integer of 0 or 1 to 4), and those in which Rf 1 is a group represented by the following formula:

[0064]

Chemical formula

[0065] (wherein n represents an integer of 1 to 4), and the like.

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

[0067] Examples of the perfluoroallyl ether include, for example, the general formula (B): CF2=CF-CF2-ORf 2 (B) (In the formula, Rf 2 represents a perfluoro organic group.) Fluoromonomers represented by the formula are exemplified.

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

[0069] The above 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. X 4 is F, Cl, Rf or O-Rf. Rf is a perfluoro organic group.) A compound represented by the formula is preferably used.

[0070] As Rf in the general formula (i), a perfluoroalkyl group having 1 to 10 carbon atoms is preferable, a perfluoroalkyl group having 1 to 5 carbon atoms is more preferable, and a perfluoroalkyl group having 1 to 4 carbon atoms is still more preferable.

[0071] The monomer having the polar group may be a non-fluorine monomer or a fluorine-containing monomer.

[0072] Examples of the non-fluorine monomer include non-fluorine monomers having a hydroxyl group such as hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, and hydroxycyclohexyl vinyl ether; non-fluorine monomers having a carboxy group such as acrylic acid, methacrylic acid, itaconic acid, succinic acid, fumaric acid, crotonic acid, maleic acid, citraconic acid, undecylenic acid, and acetylenedicarboxylic acid; non-fluorine monomers having an acid anhydride residue such as itaconic anhydride (hereinafter also referred to as "IAH"), citraconic anhydride (hereinafter also referred to as "CAH"), 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH"), succinic anhydride, fumaric anhydride, and maleic anhydride; non-fluorine monomers having a sulfo group such as vinylsulfonic acid; non-fluorine monomers having an epoxy group (glycidyl group) such as glycidyl vinyl ether and glycidyl allyl ether; non-fluorine monomers having an amino group such as aminoalkyl vinyl ether and aminoalkyl allyl ether; non-fluorine monomers having an amide group such as (meth)acrylamide and methylolacrylamide; non-fluorine monomers having a nitrile group such as acrylonitrile and methacrylonitrile. Among these, non-fluorine monomers having a carboxy group and non-fluorine monomers having an acid anhydride residue are preferable, non-fluorine monomers having an acid anhydride residue are more preferable, and cyclic non-fluorine monomers having an acid anhydride residue are still more preferable.

[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、Groups having unsaturated bonds such as -CF=CF2, -CH2-CH=CH2, -CF2-CF=CH2, -CF2-CF=CF2, -(C=O)-CH=CH2, -(C=O)-CF=CH2, -(C=O)-CH=CF2, -(C=O)-CF=CF2, -(C=O)-C(CH3)=CH2, -(C=O)-C(CF3)=CH2, -(C=O)-C(CH3)=CF2, -(C=O)-C(CF3)=CF2, -O-CH2-CH=CH2, -O-CF2-CF=CH2, -O-CH2-CH=CF2, -O-CF2-CF=CF2, etc. are included.

[0076] Since the above-mentioned modified monomer (A) has a functional group capable of reacting by radical polymerization, when used in polymerization, it reacts with the fluorine-containing monomer at the initial stage of the polymerization reaction, and it is presumed that particles having a hydrophilic group derived from the above-mentioned modified monomer (A) and high stability are formed. Therefore, when polymerization is carried out in the presence of the above-mentioned modified monomer (A), it is considered that the number of particles increases.

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

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

[0079] The modified 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) (In the formula, n1 represents an integer of 1 to 10, and Y 3 represents -SO3M 1 or -COOM 1 and M 1 represents H, NH4 or an alkali metal.) CF2=CF-(CF2C(CF3)F) n2 -Y 3 (4b) (In the formula, n2 represents an integer of 1 to 5, and Y 3 is the same as the above definition.) 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 above formula (4e) include CH2=CFCF2OCF(CF3)COOM 1 , CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM1 (where M 1 is the same as defined above).

[0088] As the above-mentioned modified monomer, in terms of the points that the coulomb efficiency of the electrochemical device can be further improved, the addition amount can be further reduced, the adhesion between the composite sheet and the substrate can be further improved, and the powder fluidity can be further improved, at least one selected from the group consisting of HFP, PAVE, PFAE, and a monomer having a polar group is preferable, and at least one selected from the group consisting of HFP, perfluoro(methyl vinyl ether) [PMVE], perfluoro(propyl vinyl ether) [PPVE], PFBE, a non-fluorine monomer having an acid anhydride residue, and the modified monomer (A) is more preferable, and at least one selected from the group consisting of HFP, PMVE, PPVE, a cyclic non-fluorine monomer having an acid anhydride residue, and a compound represented by the general formula (4e) is still more preferable, and at least one selected from the group consisting of HFP, PMVE, and PPVE is still more preferable, and HFP is still more preferable.

[0089] The above-mentioned TFE-based polymer is preferably at least one selected from the group consisting of a homopolymer of TFE and a modified PTFE containing a polymerization unit based on a TFE unit and HFP, and more preferably at least one selected from the group consisting of a homopolymer of TFE and a modified PTFE consisting only of a polymerization unit based on a TFE unit and HFP.

[0090] The above TFE-based polymer may have a core-shell structure. Examples of the TFE-based polymer having a core-shell structure include a TFE-based polymer containing a core of a high molecular weight TFE-based polymer and a shell of a lower molecular weight TFE-based polymer or a TFE copolymer in particles. Also included is modified PTFE containing a core of high molecular weight PTFE and a shell of lower molecular weight PTFE or modified PTFE in the particles. Examples of such modified PTFE include the PTFE described in Japanese Patent Application Laid-Open No. 2005-527652.

[0091] The above TFE-based polymer is preferably non-melt processable. In this specification, being 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 less than 0.05 g / 10 min, and still more preferably less than 0.01 g / 10 min. The above MFR is a value obtained as the mass (g / 10 min) of the polymer flowing out per 10 minutes from a nozzle with an inner diameter of 2.095 mm and a length of 8 mm at 372°C under a load of 5 kg using a melt indexer in accordance with ASTM D1238.

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

[0093] The above TFE-based polymer preferably has a standard specific gravity (SSG) of 2.280 or less, more preferably 2.250 or less, still more preferably 2.220 or less, even more preferably 2.200 or less, even more preferably 2.190 or less, even more preferably 2.180 or less, particularly preferably 2.170 or less, in that it can form a composite sheet with even better strength. The above SSG is preferably also 2.130 or more. The above SSG is measured by the water displacement method in accordance with ASTM D 792 using a sample molded in accordance with ASTM D 4895 89.

[0094] In the polymer composition of the present disclosure, it is preferable that the fibrillatable polymer is not fibrillated in the form of powder in terms of further improving the powder fluidity. That the fibrillatable polymer is not fibrillated in the form of powder means that the average aspect ratio of the fibrillatable polymer in the form of powder is 2.5 or less. The above average aspect ratio is preferably 2.0 or less, more preferably 1.9 or less, still 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 above average aspect ratio may also be 1.0 or more. The above average aspect ratio is determined by thinly spreading the powder of the polymer composition on a black paper surface with air so as not to shear it, observing the fibrillatable polymer contained in the polymer composition with a microscope, performing image processing on 100 or more randomly extracted particles, and obtaining the average of the ratios of the major axis to the 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 monomer having the polar group preferably includes a modified monomer having a functional group capable of reacting by radical polymerization and a hydrophilic group. Examples of such a modified monomer include the modified monomer (A) described above.

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

[0108] Although FEP is not particularly limited, a copolymer having a molar ratio of TFE unit to HFP unit (TFE unit / HFP unit) of 70 / 30 or more and less than 99 / 1 is preferable. A more preferable molar ratio is 70 / 30 or more and 98.9 / 1.1 or less, and an even more preferable molar ratio is 80 / 20 or more and 98.9 / 1.1 or less. Although FEP is not particularly limited, a copolymer having a mass ratio of TFE unit to HFP unit (TFE unit / HFP unit) of 60 / 40 or more and 98 / 2 or less is preferable. A more preferable mass ratio is 60 / 40 or more and 95 / 5 or less, and an even more preferable mass ratio is 85 / 15 or more and 92 / 8 or less. Further, as the above FEP, perfluoro(alkyl vinyl ether) compounds may be used as monomers copolymerizable with TFE and HFP, and it may be modified within the range of 0.1 to 2% by mass of all monomers. If the amount of TFE units is too small, the mechanical properties tend to decrease, and if it is too large, the melting point becomes too high and the moldability tends to decrease. The above FEP is preferably a copolymer in which the monomer unit derived from the monomer copolymerizable with TFE and HFP is 0.1 to 10 mol%, and the total of 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. Further, the above FEP may have a functional group. Examples of the functional group include those described for 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 the polymerization unit based on the monomer copolymerizable with the above-mentioned VdF and TFE is preferably less than 3.0 mol% with respect to all the polymerization units of the above-mentioned VT. If it is 3.0 mol% or more, generally, the crystallinity of the copolymer of VdF and TFE significantly decreases, and as a result, the swelling property in the non-aqueous electrolyte tends to decrease.

[0117] Examples of the monomer copolymerizable with the above-mentioned VdF and TFE include unsaturated dibasic acid monoesters such as those described in JP-A-6-172452, for example, monomethyl maleate, monomethyl citraconate, monoethyl citraconate, and vinylene carbonate. Also, those described in JP-A-7-201316, such as -SO3M, -OSO3M, -COOM, -OPO3M (where M represents an alkali metal), and -NHR which is an amine-based polar group 1 、-NR 2 R 3 (R 1 、R 2 、R 3 represents an alkyl group), and compounds having a hydrophilic polar group such as 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, and R 4 represents an alkyl group), and others, such as maleic acid and maleic anhydride. Further, CH2=CH-CH2-O-(CH2) n -OH (3≦n≦8),

[0118]

Chemical formula

[0119] CH2=CH-CH2-O-(CH2-CH2-O) n -H (1≦n≦14), CH2=CH-CH2-O-(CH2-CH(CH3)-O)n allyl ether monomers such as -H (1 ≦ n ≦ 14), and carboxylated and / or -(CF2) n allyl ethers 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 in the same way. By the way, it has been possible to infer from previous research that even compounds other than those containing polar groups as described above can slightly reduce the crystallinity of the copolymer of vinylidene fluoride and tetrafluoroethylene and impart flexibility to the material, thereby improving the adhesiveness to a current collector made of a metal foil such as aluminum or copper. From this, 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 vinylidene chloride trifluoride, hexafluoropropylene, hexafluoroisobutene, 2,3,3,3-tetrafluoropropene, CF2=CF-O-C 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 more), CH2=CF-(CF2CF2) n H (n is an integer of 1 or more), and further 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. In addition, formula (1):

[0120]

Chemical formula

[0121] (In the formula, Y represents -CH2OH, -COOH, a carboxylate, a carboxyester group or an epoxy group, X and X 1 are the same or different and each represents a hydrogen atom or a fluorine atom, and R f represents a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms or a divalent fluorine-containing alkylene group containing an ether bond having 1 to 40 carbon atoms), and a fluorine-containing ethylenic monomer having at least one functional group represented by the formula can also be used. By copolymerizing one or more of these monomers, the adhesiveness to the current collector is further improved, and the electrode active material does not peel off from the current collector even when charge and discharge are repeated, and good charge and discharge cycle characteristics can be obtained. Among these monomers, hexafluoropropylene and 2,3,3,3-tetrafluoropropene are particularly preferable from the viewpoints of flexibility and chemical resistance.

[0122] Thus, the above-mentioned VT may contain other polymerization units in addition to the VdF unit and the TFE unit, but it is more preferable that it consists only of the VdF unit and the TFE unit.

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

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

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

[0126] The above PVdF may be a homopolymer consisting only of polymerization units based on VdF, or may be composed of a polymerization unit based on VdF and a polymerization unit based on a monomer (α) copolymerizable with the above polymerization unit 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. Further, unsaturated dibasic acid monoesters as described in JP-A-6-172452, such as maleic acid monomethyl ester, citraconic acid monomethyl ester, citraconic acid monoethyl ester, and vinylene carbonate, and those having hydrophilic polar groups such as -SO3M, -OSO3M, -COOM, -OPO3M (M represents an alkali metal) and -NHR which is an amine-based polar group 1 、-NR 2 R 3 (R 1 、R 2 、R 3 represents an alkyl group), such as compounds having hydrophilic polar groups, such as 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 more), CH2=CF-(CF2CF2) n H (n is an integer of 1 or more), and further CF2=CF-O-(CF2CF(CF3)O) m -C n F 2n+1 (m, n are integers of 1 or more) can also be used. In addition, formula (1):

[0128] [Chemical formula] (In the formula, Y is -CH2OH, -COOH, carboxylate, carboxyester group or epoxy group, X and X 1 are the same or different and each is a hydrogen atom or a fluorine atom, R f represents a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms or a divalent fluorine-containing alkylene group containing an ether bond having 1 to 40 carbon atoms), and a fluorine-containing ethylenic monomer having at least one functional group represented by the formula can also be used. By copolymerizing one or more of these monomers, the adhesiveness to the current collector is further improved, and even when charge and discharge are repeated, the electrode active material does not peel off from the current collector, and good charge and discharge cycle characteristics can be obtained.

[0129] It is preferable that the above PVdF has a polymerization unit based on monomer (α) of 5 mol% or less of the total polymerization units, and more preferably 4.5 mol% or less.

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

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

[0132] The above PVdF preferably has a melting point of 130 °C or higher, more preferably 150 °C or higher, still more preferably 160 °C or higher, and preferably 230 °C or lower, more preferably 200 °C or lower, still more preferably 180 °C or lower.

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

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

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

[0136] The above VdF-based polymer preferably has an average particle diameter of 10 μm or less, more preferably 8 μm or less, still more preferably 5 μm or less, even more preferably 2 μm or less, and preferably 0.1 μm or more, more preferably 0.5 μm or more, in terms of being able to be uniformly dispersed and having excellent strength and uniformity of the compounding sheet. The average particle diameter of the VdF-based polymer can be adjusted, for example, by grinding. The above average particle diameter was measured dry at a vacuum pressure of 20 mH2O using a laser diffraction particle size distribution analyzer (LS13 320) manufactured by Beckman Coulter, and 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 cumulative particle size distribution.

[0137] The above VdF-based polymer preferably does not contain a fluorine-containing surfactant. The VdF-based polymer without a fluorine-containing surfactant can be produced, for example, by suspension polymerization. That the VdF-based polymer does not contain a fluorine-containing surfactant can be confirmed by the fact that the amount of the fluorine-containing surfactant measured by liquid chromatography-mass spectrometry is less than the detection limit, as described in the examples below.

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

[0139] Examples of the elastomer include non-fluorine 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, ethylene-methacrylate rubber, etc.; and fluoroelastomers. Among them, fluoroelastomers are preferred. The elastomer may or may not be crosslinked.

[0140] Specific examples of the fluoroelastomer include, for example, 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, or fluorophosphazene-based fluorine-containing elastomers. These can be used alone or in any combination within the range 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 content of VdF units in the VdF-based fluoroelastomer is preferably 20 mol% or more and 90 mol% or less, more preferably 40 mol% or more and 85 mol% or less, relative to the total content of VdF units and other monomer units. A more preferable lower limit is 45 mol%, and a particularly preferable lower limit is 50 mol%. A more preferable upper limit is 80 mol%.

[0142] And the comonomer in the above VdF-based fluoroelastomer is not particularly limited as long as it can copolymerize with VdF. For example, tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoroalkyl vinyl ether (PAVE), chlorotrifluoroethylene (CTFE), trifluoroethylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, hexafluoroisobutene, vinyl fluoride, iodine-containing fluorinated vinyl ether, general formula (1-1) CH2=CFRf1(1-1) (In the formula, Rf1 is a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms. When the number of carbon atoms is 2 or more, it may contain an oxygen atom between carbon-carbon atoms.) A fluorine-containing monomer represented by General formula (2-1) CHF=CHRf2(2-1) (In the formula, Rf2 is a linear or branched fluorinated alkyl group or fluorinated alkoxy group having 1 to 12 carbon atoms. When the number of carbon atoms is 2 or more, it may contain an oxygen atom between carbon-carbon atoms.) Fluorine-containing monomers such as fluorine-containing monomers represented by; fluorine-free monomers such as ethylene (Et), propylene (Pr), and alkyl vinyl ether, monomers that give a crosslinkable group (curing site), and reactive emulsifiers, etc. are mentioned, and one or two or more of these monomers and compounds can be used in combination.

[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. Both the fluorinated alkyl group and the fluorinated alkoxy group can contain an oxygen atom (-O-) between carbon-carbon atoms when the number of carbon atoms is 2 or more. The fluorinated alkyl group of Rf1 may be a partially fluorinated alkyl group in which some of the hydrogen atoms bonded to the carbon atoms are substituted by fluorine atoms, or a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atoms are substituted by fluorine atoms. Further, the fluorinated alkyl group of Rf1 may have a hydrogen atom substituted by a substituent other than a fluorine atom, but preferably does not contain a substituent other than a fluorine atom. Also, the fluorinated alkoxy group of Rf1 may be a partially fluorinated alkoxy group in which some of the hydrogen atoms bonded to the carbon atoms are substituted by fluorine atoms, or a perfluorinated alkoxy group in which all of the hydrogen atoms bonded to the carbon atoms are substituted by fluorine atoms. Further, the fluorinated alkoxy group of Rf1 may have a hydrogen atom substituted by a substituent other than a fluorine atom, but preferably does not contain a substituent other than a fluorine atom. The number of carbon atoms of Rf1 is preferably 1 to 10, more preferably 1 to 6, still more 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 both the fluorinated alkyl group and the fluorinated alkoxy group have 2 or more carbon atoms, they can contain an oxygen atom (-O-) between carbon-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 atoms are substituted by fluorine atoms, or a perfluorinated alkyl group in which all of the hydrogen atoms bonded to the carbon atoms are substituted by fluorine atoms. Further, the fluorinated alkyl group of Rf2 may have a hydrogen atom substituted by a substituent other than a fluorine atom, but preferably does not contain a substituent other than a fluorine atom. 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 a perfluorovinyl ether represented by 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=CFOCF2OCF2CF3, or CF2=CFOCF2OCF2CF2OCF3.

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

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

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

[0150] For the VdF / TFE / HFP copolymer, the composition of VdF / TFE / HFP is preferably (30 to 80) / (4 to 35) / (10 to 35) (mol%).

[0151] For the VdF / PAVE copolymer, the composition of VdF / PAVE is preferably (65 to 90) / (35 to 10) (mol%). Also, the composition of VdF / PAVE being (50 to 78) / (50 to 22) (mol%) is also a preferred form.

[0152] As the VdF / TFE / PAVE copolymer, those having a composition of VdF / TFE / PAVE of (40 to 80) / (3 to 40) / (15 to 35) (mol%) are preferred.

[0153] As the VdF / HFP / PAVE copolymer, those having a composition of VdF / HFP / PAVE of (65 to 90) / (3 to 25) / (3 to 25) (mol%) are preferred.

[0154] As the VdF / HFP / TFE / PAVE copolymer, those having a composition of VdF / HFP / TFE / PAVE of (40 to 90) / (0 to 25) / (0 to 40) / (3 to 35) (mol%) are preferred, and those having a composition of (40 to 80) / (3 to 25) / (3 to 40) / (3 to 25) (mol%) are more preferred.

[0155] As the VdF / fluorine-containing monomer (1-1) or (2-1) - based copolymer represented by VdF / Formula (1-1) or (2-1), those in which the VdF / fluorine-containing monomer (1-1) or (2-1) units are 87 / 13 to 20 / 80 (mol%), and the other monomer units other than VdF and the fluorine-containing monomer (1-1) or (2-1) are 0 to 50 mol% of all monomer units are preferred, and it is more preferred that the molar ratio of the VdF / fluorine-containing monomer (1-1) or (2-1) units is 80 / 20 to 20 / 80. Also, a form in which the composition of the VdF / fluorine-containing monomer (1-1) or (2-1) units is 78 / 22 to 50 / 50 (mol%) is also a preferred form. Further, those in which the VdF / fluorine-containing monomer (1-1) or (2-1) units are 87 / 13 to 50 / 50 (mol%), and the other monomer units other than VdF and the fluorine-containing monomer (1-1) or (2-1) are 1 to 50 mol% of all monomer units are also preferred. As the other monomers other than VdF and the fluorine-containing monomer (1-1) or (2-1), the monomers exemplified as the comonomers of VdF such as TFE, HFP, PMVE, perfluoroethyl vinyl ether (PEVE), PPVE, CTFE, trifluoroethylene, hexafluoroisobutene, vinyl fluoride, Et, Pr, alkyl vinyl ether, monomers giving crosslinkable groups, and reactive emulsifiers are preferred, and among them, PMVE, CTFE, HFP, and TFE are more preferred.

[0156] The TFE / Pr-based fluorine-containing elastomer refers to a fluorine-containing copolymer consisting of 45-70 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, which can be used alone or in any combination.

[0160] The fluoroelastomer preferably has a fluorine content of 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more. The upper limit of the fluorine content is not particularly limited, but is preferably 71% by mass or less. The fluorine content is a value calculated from the composition of the fluoroelastomer measured by 19F-NMR. The molecular weight was calculated from the composition ratio, and the mass of 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, and X 3 is a cyano group, a carboxy group, an alkoxycarbonyl group, an iodine atom, or a bromine atom.) A monomer represented by the general formula: 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, and X 4 is a cyano group, a carboxy group, an alkoxycarbonyl group, an iodine atom, a bromine atom, or -CH2OH.) Even if a monomer represented by the formula is used as another monomer, it may be used.

[0166] Among them, 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 preferable. Further, it may contain a repeating unit based on a monomer that provides a cross-linking site, but in one embodiment of the present disclosure, it does not contain a cross-linking agent.

[0167] The above fluororubber 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 of 1.0 to 30.0, more preferably 1.5 to 25.0, in order to have good adhesion and flexibility and good solubility in solvents. The above number average molecular weight (Mn), mass average molecular weight (Mw), and Mw / Mn are values measured by the GPC method.

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

[0169] The above fluororubber preferably satisfies the following inequality for the terminal structure: 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). By making the terminal functional group satisfy the above formula, the adhesion and flexibility are good and it has excellent functions.

[0170] Note that satisfying the above general formula does not mean that the fluorine-containing copolymer has all functional groups of [-CH3], [-CF2H], [-CH2OH], [-CH2I], [-OC(O)RH], and [-COOH]. Among these, regarding the end groups present in the fluorine-containing copolymer, it means that the number ratio is within the above-described range.

[0171] The abundance of each end group of the fluorine-containing copolymer can be measured by NMR analysis.

[0172] For example, the end group analysis of NMR is performed by the proton solution NMR method. The analysis sample is adjusted to a 20% by mass solution using Acetone-d6 as the solvent and then measured. The reference peak is set at 2.05 ppm at the peak top of acetone. Measuring device: VNMRS400 manufactured by Varian Resonance frequency: 399.74 (Sfrq) Pulse width: 45° Each end corresponds to the one at the following peak positions. [-CH3]: 1.72 to 1.86 ppm [-CF2H]: 6.1 to 6.8 ppm [-CH2OH]: 3.74 to 3.80 ppm [-CH2I]: 3.87 to 3.92 ppm [-OC(O)RH]: 1.09 to 1.16 ppm [-COOH]: 10 to 15 ppm Based on the integral value of each peak specified by the above measurement, the amount of the functional group is calculated from each peak intensity, and calculated by the following formula based on the result. ([-CH2OH] + [-COOH]) / ([-CH3] + [-CF2H] + [-CH2OH] + [-CH2I] + [-OC(O)RH] + [-COOH])

[0173] The method of making [-CH2OH] and [-COOH] fall within the above-described predetermined ranges is not particularly limited and can be controlled by known methods (for example, the selection and amount of initiator used in polymerization, etc.).

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

[0175] Among the above thermoplastic polymers, 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 preferably, and at least one selected from the group consisting of PVdF and VT is particularly preferred. It is also preferred that the above VdF-based polymer is a fluoroelastomer.

[0176] The content of the above thermoplastic polymer in the polymer composition of the present disclosure can further improve the Coulomb efficiency of the electrochemical device, can further reduce the addition amount, can further improve the adhesion between the binder sheet and the substrate, and can further improve the powder fluidity. Therefore, it is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more, even more preferably 8% by mass or more, particularly preferably 10% by mass or more. Also, it is preferably less than 50% by mass, more preferably 45% by mass or less, still 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 fibrillatable polymer and the thermoplastic polymer with respect to 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, still 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 (In the formula, m is 4 to 20. M 1 is H, a metal atom, NR 5 4 (R 5is the same or different and is H or an organic group having 1 to 10 carbon atoms), an optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium. p is 1 or 2.) General formula (2): (H-(CF2) n -SO3) q M 2 (In the formula, n is 4 to 20. M 2 is H, a metal atom, NR 5 4 (R 5 is the same as above), an optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium. q is 1 or 2.)

[0179] The above M 1 and M 2 Examples of the above metal atom as M include monovalent and divalent metal atoms, and include alkali metals (Group 1) or alkaline earth metals (Group 2). Specifically, Na, K, Li, etc. are exemplified. The four Rs 5 may be the same or different. R 5 is preferably H or an organic group having 1 to 10 carbon atoms, and more preferably H or an organic group having 1 to 4 carbon atoms. The organic group as R 5 is preferably an organic group not containing fluorine.

[0180] In general formula (1), m is preferably 6 or more, more preferably 8 or more, still more preferably 11 or more, still more preferably 13 or more, particularly preferably 15 or more, and preferably 18 or less, more preferably 16 or less. In general formula (2), n is preferably 6 or more, more preferably 8 or more, still more preferably 11 or more, still more preferably 13 or more, particularly preferably 15 or more, and preferably 18 or less, more preferably 16 or less.

[0181] The polymer composition of the present disclosure may contain one or more of compound (1), or may contain two or more, or may contain three or more.

[0182] When the polymer composition of the present disclosure contains compound (1), the content of compound (1) (when two or more are present, the content for each component) may be 10 mass ppm or less, preferably 5000 mass ppb or less, more preferably 1000 mass ppb or less, still more preferably 500 mass ppb or less, still more preferably 100 mass ppb or less, still more preferably 50 mass ppb or less, still more preferably 25 mass ppb or less, still more preferably 10 mass ppb or less, and particularly preferably 10 mass ppb or less, based on the above polymer composition. The lower limit is not particularly limited, and it 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 compounds (2), or may contain two or more compounds (2), or may contain three or more compounds (2).

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

[0185] The polymer composition containing compound (1) and / or (2) is obtained by using a hydrocarbon surfactant. The polymer composition of the present disclosure may contain a hydrocarbon surfactant together with a fibrillatable polymer, a thermoplastic polymer, and compound (1) and / or (2). The content of the hydrocarbon surfactant in the above polymer composition is not particularly limited, but is usually 100 mass ppm to 10 mass %. It is preferable that in the above hydrocarbon surfactant, the ratio of the hydrogen atoms bonded to the carbon atoms substituted with fluorine atoms is 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted 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, a metal atom, NR 5 4 (R 5 may be the same or different and is H or an organic group having 1 to 10 carbon atoms (preferably an organic group not containing fluorine), an imidazolium optionally having a substituent, a pyridinium optionally having a substituent, or a phosphonium optionally having a substituent. q is 1 or 2.)

[0187] Not substantially containing compound (3) means that the content of compound (3) is 25 mass ppb or less with respect to the above polymer composition. The content of compound (3) is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, still more preferably 10 mass ppb or less with respect to the above TFE-based polymer. The lower limit is not particularly limited, and may be 0 mass ppb, may be 0.1 mass ppb, or may be 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 more preferably 500 mass ppb or less, still 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 with respect to the above polymer composition. The lower limit is not particularly limited, and it 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 the content of each of them is preferably 1000 mass ppb or less with respect to the above polymer composition. General formula (5): (H-(CF2) 13 -COO) p M 1 (In the formula, M 1 is H, a metal atom, NR 5 4 (R 5 may be the same or different, and is H or an organic group having 1 to 10 carbon atoms (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, a metal atom, NR 5 4 (R 5 is the same as above), 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.)

[0192] When the polymer composition of the present disclosure contains compound (5), the content of compound (5) is more preferably 500 mass ppb or less, still 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 with respect to the above polymer composition. The lower limit is not particularly limited and may be 0.1 mass ppb or 1 mass ppb.

[0193] When the polymer composition of the present disclosure contains compound (5'), the content of compound (5') is more preferably 500 mass ppb or less, still 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 with respect to the above polymer composition. The lower limit is not particularly limited and 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 by liquid chromatography-mass spectrometry as described in the examples below.

[0195] The polymer composition of the present disclosure preferably contains substantially no water. Thereby, gas generation and deterioration of electrochemical device characteristics can be suppressed. In addition, since electrode active materials and solid electrolytes to be combined can be widely selected, it is advantageous in the production process. Substantially free of water means that the water content with respect to the above polymer composition is 0.050 mass% or less. The above moisture content is preferably 0.030% by mass or less, more preferably 0.010% by mass or less, still 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 above moisture content is measured by the following method. Measure the mass of the polymer composition before and after heating at 150 °C for 2 hours, and calculate according to the following formula. Take the sample three times, calculate each time, then find the average, and adopt the average value. Moisture content (% by mass) = [(mass of the polymer composition before heating (g)) - (mass of the polymer composition after heating (g))] / (mass of the polymer composition before heating (g)) × 100

[0196] The polymer composition of the present disclosure preferably substantially does not contain a fluorine-containing compound having a molecular weight of 1000 or less. Substantially not containing the above fluorine-containing compound means that the amount of the above fluorine-containing compound is 25 mass ppb or less with respect to the above polymer composition. The amount of the above fluorine-containing compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, still more preferably 10 mass ppb or less, even more preferably less than 10 mass ppb, even more preferably 1 mass ppb or less, even more preferably less than 1 mass ppb, and particularly preferably less than the lower limit of quantification. The lower limit is not particularly limited and may be an amount less than the lower limit of quantification.

[0197] The amount of the above fluorine-containing compound having a molecular weight of 1000 or less is measured by the following method. Weigh 1 g of the sample, add 10 g (12.6 ml) of methanol, perform ultrasonic treatment for 60 minutes to obtain an extract. Appropriately concentrate the obtained extract by nitrogen purging, and measure the fluorine-containing compound in the concentrated extract by LC / MS / MS. Extract the molecular weight information from the obtained LC / MS spectrum, and confirm the match with the structural formula of the candidate fluorine-containing compound. Prepare aqueous solutions with a content of 5 levels or more of the standard substance, perform LC / MS analysis on the aqueous solutions with each content, plot the relationship between the content and the area of the peak corresponding to the content, and draw a calibration curve. Using the above calibration curve, convert the area of the peak in the LC / MS chromatogram of the fluorine-containing compound in the extract into the content of the fluorine-containing compound. Note that the lower limit of quantification in this measurement method is 10 mass ppb.

[0198] Examples of the fluorine-containing compound with a molecular weight of 1000 or less include fluorine-containing compounds having a hydrophilic group with a molecular weight of 1000 g / mol or less. The molecular weight of the above fluorine-containing compound is preferably 800 or less, and more preferably 500 or less. Polymer particles obtained by polymerization carried out in the presence of a fluorine-containing surfactant usually contain, in addition to the target polymer, the fluorine-containing surfactant. In this specification, the fluorine-containing surfactant is the one used during polymerization. The fluorine-containing compound with a molecular weight of 1000 or less may be a compound that is not added during polymerization, for example, a compound that is by-produced during polymerization. Note that when the fluorine-containing compound with a molecular weight of 1000 or less contains an anionic part and a cationic part, it means a fluorine-containing compound in which the molecular weight of the anionic part is 1000 or less. The fluorine-containing compound with a molecular weight of 1000 or less does not include fibrillatable polymers and thermoplastic polymers.

[0199] Examples of the above hydrophilic group may be -COOM, -SO2M, or -SO3M, and -COOM, -SO3M (in each formula, M is H, a metal atom, NR 14. It may be an imidazolium optionally having a substituent, a pyridinium optionally having a substituent, or a phosphonium optionally having a substituent, and R 1 is H or an organic group. Anionic groups such as ) etc. can be mentioned.

[0200] As the above fluorine-containing surfactant, a surfactant containing fluorine with a molecular weight of the anionic part of 1000 or less (anionic fluorine-containing surfactant) can also be used. The above "anionic part" means the part excluding the cation of the above fluorine-containing surfactant. For example, in the case of F(CF2) n1 COOM, it is the part of "F(CF2) n1 COO". As the above anionic fluorine-containing surfactant, the following general formula (N 0 ): X n0 -Rf n0 -Y 0 (N 0 ) (In the formula, X n0 is H, Cl or and F. Rf n0 is an alkylene group having 3 to 20 carbon atoms, linear, branched or cyclic, and part or all of the H is substituted by F, and the alkylene group may contain one or more ether bonds, and part of the H may be substituted by Cl. Y 0 is an anionic group.) Compounds represented by are mentioned. The anionic group of Y 0 may be -COOM, -SO2M, or -SO3M, and may be -COOM or -SO3M. M is H, a metal atom, NR 1 4. It may be an imidazolium optionally having a substituent, a pyridinium optionally having a substituent, or a phosphonium optionally having a substituent, and R 1 is H or an organic group. Examples of the above metal atoms include alkali metals (Group 1), alkaline earth metals (Group 2), etc., and for example, Na, K or Li. R 1 may be H or an organic group of C 1-10 and may be H or C1-4 may be an organic group of H or C 1-4 and may be an alkyl group. M is H, a metal atom or NR 1 4, may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 1 4, may be H, Na, K, Li or NH4. Said Rf n0 may be one in which 50% or more of H is substituted with fluorine.

[0201] The fluorine-containing surfactant may be one kind of fluorine-containing surfactant or a mixture containing two or more kinds of fluorine-containing surfactants.

[0202] Examples of the fluorine-containing surfactant include compounds represented by the following formulas. 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 [Chemical formula] (In each formula, M is H, a metal atom, NR 14. It is imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. R 1 is H or an organic group.). The polymer composition of the present disclosure preferably does not substantially contain any of the fluorine-containing compounds represented by the above formulae.

[0203] In each of the above formulae, M may be H, a metal atom or NR 1 4, may be H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 1 4, and may be H, Na, K, Li or NH4. R 1 may be H or an organic group of C 1-10 may be H or an organic group of C 1-4 may be H or an organic group of C 1-4 and may be an alkyl group of C.

[0204] When the polymer composition of the present disclosure does not substantially contain any of the fluorine-containing compounds represented by the above formulae, generation of gas and deterioration of electrochemical device characteristics can be further suppressed. Not substantially containing any of the fluorine-containing compounds represented by the above formulae means that the amount of the fluorine-containing compound is 25 mass ppb or less with respect to the above polymer composition. The amount of the fluorine-containing compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, still more preferably 10 mass ppb or less, even more preferably less than 10 mass ppb, still even more preferably 1 mass ppb or less, still even more preferably less than 1 mass ppb, and particularly preferably less than the quantification lower limit. The lower limit is not particularly limited and may be an amount less than the quantification lower limit.

[0205] The polymer composition of the present disclosure has the following general formula: [C n-1 F 2n-1 COO - M + (In the formula, n is an integer from 9 to 14, preferably an integer from 9 to 12, and M + represents a cation.) It is also preferable that the fluorine-containing compound represented by the formula is substantially not contained. Thereby, generation of gas and deterioration of the characteristics of the electrochemical device can be further suppressed. The cation M in the above formula + constituting M is the same as the above-described M. Substantially not containing the fluorine-containing compound represented by the above formula means that the amount of the fluorine-containing compound is 25 mass ppb or less with respect to the above polymer composition. The amount of the fluorine-containing compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, still more preferably 10 mass ppb or less, even more preferably less than 10 mass ppb, still more preferably 1 mass ppb or less, even more preferably less than 1 mass ppb, and particularly preferably less than the lower limit of quantification. The lower limit is not particularly limited and may be an amount less than the lower limit of quantification.

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

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

[0208] The endothermic peak temperature is defined as the temperature corresponding to each minimum point in regions (A) to (C) of the melting heat curve when the temperature is increased at a rate of 10 °C / min using a differential scanning calorimeter [DSC] for a polymer composition that has no history of heating to a temperature of 300 °C or higher.

[0209] The polymer composition of the present disclosure preferably also has a 0.1% mass loss temperature of 340 °C or higher. The 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 above 0.1% mass loss temperature is more preferably 350 °C or higher, still more preferably 370 °C or higher, and preferably 400 °C or lower, more preferably 390 °C or lower. The above 0.1% mass loss temperature is a value measured by the following method. Weigh accurately about 10 mg of a polymer composition that has no history of heating to a temperature of 300 °C or higher, place it in a dedicated aluminum pan, and measure TG·DTA (simultaneous differential thermal and thermogravimetric analyzer). The 0.1% mass loss temperature is defined as the temperature corresponding to the point where the weight has decreased by 0.1 mass% when the temperature of the aluminum pan is increased from 25 °C to 600 °C at a rate of 10 °C / min under an air atmosphere.

[0210] The polymer composition of the present disclosure preferably also has a 1.0% mass loss temperature of 370 °C or higher. The fact that the 1.0% mass loss temperature is within the above range indicates that the polymer composition contains a perfluoropolymer such as PFA or FEP as a thermoplastic polymer. The above 1.0% mass loss temperature is more preferably 400 °C or higher, still more preferably 420 °C or higher, even more preferably 440 °C or higher, even more preferably 460 °C or higher, and preferably 492 °C or lower. The above 1.0% mass loss temperature is a value measured by the following method. Weigh accurately about 10 mg of a polymer composition without a heating history at a temperature of 300 °C or higher, place it in a dedicated aluminum pan, and measure TG·DTA (simultaneous differential thermal and thermogravimetric analyzer). The 1.0% mass loss temperature is the temperature corresponding to the point where the weight has decreased by 1.0 mass% when the temperature of the aluminum pan is raised from 25 °C to 600 °C at a rate of 10 °C / min under an air atmosphere.

[0211] In terms of further improving the powder fluidity of the polymer composition of the present disclosure, the average aspect ratio in the form of powder is preferably 2.5 or less, more preferably 2.0 or less, still 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 above average aspect ratio may also be 1.0 or more. The above average aspect ratio is obtained by thinly spreading the powder of the polymer composition on a black paper surface with air so as not to apply shear, observing the polymer composition with an electron microscope, performing image processing on 100 or more randomly extracted particles, and calculating the average of the ratios of the major axis to the minor axis.

[0212] The polymer composition of the present disclosure may have an average secondary particle diameter of 350 μm or more, preferably 400 μm or more, more preferably 450 μm or more, still more preferably 500 μm or more, still more preferably 550 μm or more, particularly preferably 600 μm or more, and preferably 1000 μm or less, more preferably 900 μm or less, still more preferably 800 μm or less, and still 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, still more preferably 0.45 g / ml or more, still more preferably 0.48 g / ml or more, and particularly preferably 0.50 g / ml or more. The upper limit is not particularly limited and 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 it is preferably a powder in that it can be mixed with an electrode active material or a solid electrolyte without using a large amount of a dispersion medium. Note that the TFE-based polymer composition may be in a form other than a powder, for example, a dispersion or a molded body.

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

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

[0217] The aqueous dispersion of the fibrillatable 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-based surfactant. Hereinafter, a method for producing an aqueous dispersion when the fibrillatable polymer is a TFE-based polymer will be described in detail.

[0218] In the hydrocarbon-based surfactant, preferably, the ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0219] The hydrocarbon-based surfactant is preferably a carboxylic acid type hydrocarbon-based surfactant. The carboxylic acid type hydrocarbon-based surfactant is not limited as long as it has a carboxy group (-COOH) or a group in which a hydrogen atom of the carboxy group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.). For example, from among specific hydrocarbon-based surfactants described later and other compounds having surfactant properties, a hydrocarbon-based surfactant having a carboxy group or a group in which a hydrogen atom of the carboxy group is substituted with an inorganic cation can be used.

[0220] The above hydrocarbon surfactant is preferably a sulfonic acid type hydrocarbon surfactant. The sulfonic acid type hydrocarbon surfactant is not limited as long as it has a -SO3H group, -OSO3H group, or a group in which a 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 later and other compounds having surfactant properties, a hydrocarbon surfactant having a -SO3H group, -OSO3H group, or a group in which a hydrogen atom of these groups is substituted with an inorganic cation can be used.

[0221] The above hydrocarbon surfactant preferably exhibits water solubility in terms of good emulsifying performance. That the hydrocarbon surfactant exhibits water solubility means that the maximum concentration of the hydrocarbon surfactant dissolved in water at 85 °C is 100 mass ppm or more. The above maximum concentration in water is preferably 500 mass ppm or more, more preferably 1000 mass ppm or more, still more preferably 2000 mass ppm or more, still more preferably 3000 mass ppm or more, still more preferably 5000 mass ppm or more, still more preferably 1 mass% or more, still more preferably 3 mass% or more, still more preferably 5 mass% or more, particularly preferably 10 mass% or more, and may be 50 mass% or less.

[0222] The above emulsion polymerization preferably includes a step of performing emulsion polymerization of only tetrafluoroethylene or emulsion polymerization of tetrafluoroethylene and a modified monomer copolymerizable with the 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 not all at once, but over time, without interruption or in portions. The specific hydrocarbon surfactant is, for example, a hydrocarbon surfactant having one or more carbonyl groups (excluding the carbonyl group in the carboxy group), or a hydrocarbon surfactant obtained by subjecting a hydrocarbon surfactant having one or more carbonyl groups (excluding the carbonyl group in the carboxy group) to radical treatment or oxidation treatment. The above radical treatment may be any treatment that generates radicals in a hydrocarbon surfactant having one or more carbonyl groups (excluding the carbonyl group in the carboxy group). For example, deionized water and a hydrocarbon surfactant are added to a reactor, the reactor is sealed, the system is purged with nitrogen, the reactor is heated and pressurized, a polymerization initiator is charged, and after stirring for a certain period of time, the reactor is depressurized until it reaches atmospheric pressure and then cooled. The above oxidation treatment is a treatment in which an oxidizing agent is added to a hydrocarbon surfactant having one or more carbonyl groups (excluding the carbonyl group in the carboxy group). Examples of the oxidizing agent include oxygen, ozone, hydrogen peroxide solution, manganese(IV) oxide, potassium permanganate, potassium dichromate, nitric acid, sulfur dioxide, and the like. By the above production method, it is possible to produce a TFE-based 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 manufacturing method, in the step of continuously adding the specific hydrocarbon surfactant, it is preferable that the addition of the hydrocarbon surfactant to the aqueous medium starts when the solid content of the TFE-based polymer formed in the aqueous medium is less than 0.60% by mass. When it is 0.5% by mass or less, it is preferable that the addition of the specific hydrocarbon surfactant to the aqueous medium starts. It is more preferable that the addition of the specific hydrocarbon surfactant starts when the solid content is 0.3% by mass or less, still more preferable when it is 0.2% by mass or less, still more preferable when it is 0.1% by mass or less, and particularly preferable to start adding at the same time as the polymerization initiation. The solid content is the concentration with respect to the total of the aqueous medium and the TFE-based polymer.

[0225] In the step of continuously adding the specific hydrocarbon surfactant, the addition amount of the specific hydrocarbon surfactant is preferably 0.01 to 10% by mass with respect to 100% by mass of the aqueous medium. A more preferable lower limit is 0.05% by mass, a still more preferable lower limit is 0.1% by mass, a more preferable upper limit is 5% by mass, and a still more preferable upper limit is 1% by mass.

[0226] In the step of performing emulsion polymerization of only tetrafluoroethylene or emulsion polymerization of tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene in an aqueous medium in the presence of the specific hydrocarbon surfactant, the amount of the specific hydrocarbon surfactant is preferably large, and is preferably 0.0001 to 10% by mass with respect to 100% by mass of the aqueous medium. A more preferable lower limit is 0.001% by mass, and a more preferable upper limit is 1% by mass. If it is less than 0.0001% by mass, the dispersing power may be insufficient, and if it exceeds 10% by mass, an effect commensurate with the amount cannot be obtained, and instead, the polymerization rate may decrease or the reaction may stop. The amount of the specific hydrocarbon surfactant is appropriately determined according to the type of monomer used, the molecular weight of the target TFE-based polymer, etc.

[0227] As the specific hydrocarbon surfactant, a surfactant represented by the formula: R-X (wherein R is a fluorine-free organic group having 1 to 2000 carbon atoms and having one or more carbonyl groups (excluding the carbonyl group in the carboxy group), and X is -OSO3X 1 , -COOX 1 or -SO3X 1 (wherein X 1 is H, a metal atom, NR 1 4, an optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium, and R 1 is H or an organic group (preferably an organic group not containing fluorine), and they may be the same or different)), and at least one selected from the group consisting of the surfactant (e) described later is preferable. R preferably has 500 or less carbon atoms, more preferably 100 or less carbon atoms, still more preferably 50 or less carbon atoms, and still more preferably 30 or less carbon atoms. As the specific hydrocarbon surfactant, the following formula (a):

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0228] The surfactant (a) can be produced, for example, by the production method described in International Publication No. 2020 / 022355.

[0229] The surfactant (b) can be produced, for example, by the production method described in International Publication No. 2020 / 022355.

[0230] The surfactant (c) can be produced, for example, by the production method described in International Publication No. 2020 / 022355.

[0231] The surfactant (d) can be produced, for example, by the production method described in International Publication No. 2020 / 022355.

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

[0233] It is also preferable that the specific hydrocarbon-based surfactant is a carboxylic acid type hydrocarbon-based surfactant. The carboxylic acid type hydrocarbon-based surfactant is not limited as long as it has a carboxy group (-COOH) or a group in which a hydrogen atom of the carboxy group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.). For example, among the above-described specific hydrocarbon-based surfactants, a hydrocarbon-based surfactant having a carboxy group or a group in which a hydrogen atom of the carboxy group is substituted with an inorganic cation can be used. It is preferable that the ratio of the hydrogen atoms bonded to the carbon atoms of the carboxylic acid type hydrocarbon-based surfactant substituted with fluorine atoms is 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0234] Preferably, as the carboxylic acid type hydrocarbon-based surfactant, among at least one selected from the group consisting of the surfactant (c) represented by the above formula (c) and the surfactant (d) represented by the above formula (d), those having a carboxy group (-COOH) or a group in which a hydrogen atom of the carboxy group is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.) are preferable.

[0235] The above-mentioned specific hydrocarbon surfactant is also preferably a sulfonic acid type hydrocarbon surfactant. The sulfonic acid type hydrocarbon surfactant is not limited as long as it has a -SO3H group, -OSO3H group, or a group in which a hydrogen atom of these groups is substituted with an inorganic cation (for example, a metal atom, ammonium, etc.). For example, among the above-mentioned specific hydrocarbon surfactants, a hydrocarbon surfactant having a -SO3H group, -OSO3H group, or a group in which a hydrogen atom of these groups is substituted with an inorganic cation can be used. The above-mentioned sulfonic acid type hydrocarbon surfactant preferably has a ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms of 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0236] The polymer composition of the present disclosure can be efficiently produced by using at least one of the above-mentioned specific hydrocarbon surfactants. Further, the polymer composition of the present disclosure may be produced by simultaneously using two or more of the above-mentioned specific hydrocarbon surfactants, or may be produced by simultaneously using a compound having other surfactant properties other than the above-mentioned specific hydrocarbon surfactant as long as it has volatility or remains in a molded article made of a TFE-based polymer or the like.

[0237] As the compound having other surfactant properties, for example, those described in JP-T-2013-542308, JP-T-2013-542309, JP-T-2013-542310, etc. can be used.

[0238] The compound having other surfactant properties may be a surfactant having a hydrophilic moiety and a hydrophobic moiety on the same molecule, for example, a hydrocarbon surfactant (excluding the above-mentioned specific hydrocarbon surfactant). These may be cationic, nonionic or anionic. It is preferable that the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms in the above compound is 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0239] The cationic surfactant usually has a positively charged hydrophilic moiety such as an alkylated ammonium halide such as alkylated ammonium bromide, and a hydrophobic moiety such as a long-chain fatty acid. It is preferable that the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms in the above cationic surfactant is 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0240] The anionic surfactant usually has a hydrophilic moiety such as a carboxylate, a sulfonate or a sulfate, and a hydrophobic moiety which is a long-chain hydrocarbon moiety such as an alkyl. It is preferable that the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms in the above anionic surfactant is 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0241] The nonionic surfactant usually does not contain a charged group and has a hydrophobic moiety which is a long-chain hydrocarbon. The hydrophilic moiety of the nonionic surfactant contains a water-soluble functional group such as a chain of ethylene ether derived from polymerization with ethylene oxide. It is preferable that the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms in the above nonionic surfactant is 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0242] Examples of compounds having other surface activity include compounds represented by the formula R-L-M (wherein R is a linear or branched alkyl group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring; L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or -COO - ; and M is H, a metal atom, NR 5 4 (wherein R 5 may be the same or different and is H or an organic group (preferably an organic group not containing fluorine), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent). -ArSO3 - is an arylsulfonate). Anionic surfactants represented by the formula are also included. R 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, those represented by CH3-(CH2) n -L-M (wherein n is an integer of 6 to 17; and L and M are the same as above) typified by lauric acid are included. Mixtures in which R is an alkyl group having 12 to 16 carbon atoms and L-M is a sulfate or sodium dodecyl sulfate (SDS) can also be used. Examples of compounds having other surface activity also include R 6 (-L-M)2 (wherein R 6 is a linear or branched alkylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylene group having 3 or more carbon atoms which may have a substituent, and when the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring; L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or -COO - ; and M is H, a metal atom, NR 54. An anionic surfactant represented by an optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium, and R 5 is H or an organic group (preferably an organic group not containing fluorine), -ArSO3 - is an arylsulfonate. Also included are anionic surfactants represented by the following formula.) As other compounds having surfactant properties, R 7 (-L-M)3 (wherein R 7 is a linear or branched alkylidine group having 1 or more carbon atoms which may have a substituent, or a cyclic alkylidine group having 3 or more carbon atoms which may have a substituent. When the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring. L is -ArSO3 - , -SO3 - , -SO4-, -PO3 - or -COO - and M is H, a metal atom, NR 5 4. An anionic surfactant represented by an optionally substituted imidazolium, an optionally substituted pyridinium or an optionally substituted phosphonium, and R 5 is H or an organic group (preferably an organic group not containing fluorine). -ArSO3 - is an arylsulfonate. Also included are anionic surfactants represented by the following formula.)

[0243] Examples of siloxane hydrocarbon-based surfactants include those described in Silicone Surfactants, R.M. Hill, Marcel Dekker, Inc., ISBN: 0-8247-00104. The structure of siloxane surfactants includes a distinct hydrophobic part and a hydrophilic part. The hydrophobic part contains one or more dihydrocarbylsiloxane units, where the substituents on the silicone atom are completely hydrocarbon. In the sense that when the carbon atoms of the hydrocarbyl groups can be substituted by halogens such as fluorine, these siloxane surfactants can also be regarded as hydrocarbon surfactants, that is, the monovalent substituents on the carbon atoms of the hydrocarbyl groups are hydrogen. Preferably, for the above siloxane surfactants, the ratio of the hydrogen atoms bonded to the carbon atoms substituted by fluorine atoms is 50% or less, more preferably 25% or less, still more preferably 10% or less, and most preferably 0% (not substituted by fluorine atoms at all).

[0244] Siloxane hydrocarbon surfactants are also disclosed in U.S. Patent No. 6,841,616.

[0245] As other compounds having surfactant properties, anionic hydrocarbon surfactants are preferred. As the anionic hydrocarbon surfactants, those described above can be adopted. For example, the following hydrocarbon surfactants can be preferably adopted.

[0246] As the above anionic hydrocarbon surfactant, for example, 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 imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, and R 101 is H or an organic group (preferably an organic group not containing fluorine), and they may be the same or different.) Compounds (α) represented by are exemplified. As the organic group of R 101 , an alkyl group is preferred. As R 101 , H or an organic group having 1 to 10 carbon atoms is preferred, H or an organic group having 1 to 4 carbon atoms is more preferred, and H or an alkyl group having 1 to 4 carbon atoms is still more preferred. From the perspective of interfacial activity, R 100 preferably has 2 or more carbon atoms, more preferably 3 or more carbon atoms. Also, from the perspective of water solubility, R 100 preferably has 29 or fewer carbon atoms, more preferably 23 or fewer carbon atoms. Examples of the metal atom of M include alkali metals (Group 1), alkaline earth metals (Group 2), etc., and Na, K, or Li is preferred. M is preferably H, a metal atom, or NR 101 4, more preferably H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 101 4, still more preferably H, Na, K, Li, or NH4, even more preferably Na, K, or NH4, particularly preferably Na or NH4, and most preferably NH4.

[0247] Examples of the compound (α) also include an anionic surfactant represented by R 102 -COOM (wherein R 102 is a linear or branched alkyl group, alkenyl group, alkylene group, or alkenylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group, or alkenylene group having 3 or more carbon atoms which may have a substituent, and these may contain an ether bond. When having 3 or more carbon atoms, it may contain a monovalent or divalent heterocyclic ring or may form a ring. M is the same as above). Specifically, those represented by CH3-(CH2) n -COOM (wherein n is an integer from 2 to 28. M is the same as above) are included.

[0248] Examples of the anionic hydrocarbon surfactant also include, for example, the following formula (β): R 100 -SO3M (β) (wherein R 100 is a monovalent organic group containing 1 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, where R 101 is H or an organic group (preferably an organic group not containing fluorine), and they may be the same or different. The compound (β) represented by ) is also included. R 101 The organic group is preferably an alkyl group. R 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 still more preferably H or an alkyl group having 1 to 4 carbon atoms. From the viewpoint of surfactant properties, the number of carbon atoms of R 100 is preferably 2 or more, more preferably 3 or more. Also, from the viewpoint of water solubility, the number of carbon atoms of R 100 is preferably 29 or less, more preferably 23 or less. Examples of the metal atom of M above include alkali metals (Group 1), alkaline earth metals (Group 2), etc., and Na, K or Li is preferred. M is preferably H, a metal atom or NR 101 4, more preferably H, an alkali metal (Group 1), an alkaline earth metal (Group 2) or NR 101 4, still more preferably H, Na, K, Li or NH4, even more preferably Na, K or NH4, particularly preferably Na or NH4, and most preferably NH4.

[0249] Examples of the above compound (β) include an anionic surfactant represented by R 102 -SO3M (wherein R 102 is a linear or branched alkyl group, alkenyl group, alkylene group or alkenylene group having 1 or more carbon atoms which may have a substituent, or a cyclic alkyl group, alkenyl group, alkylene group or alkenylene group having 3 or more carbon atoms which may have a substituent, and these may contain an ether bond. When the number of carbon atoms is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring. M is the same as above). Specifically, those represented by CH3-(CH2) n -SO3M (wherein n is an integer from 2 to 28. M is the same as above) are included.

[0250] As the above anionic hydrocarbon surfactant, the following formula I: R-(XZ) n (I) (In the formula, R is a hydrophobic hydrocarbon moiety containing one or more saturated or unsaturated, acyclic or cyclic aliphatic groups. The percentage of the total number of CH3 groups relative to the total of CH3, CH2 and CH groups in one or more aliphatic groups is at least about 70%, and the hydrophobic moiety does not contain siloxane units. Each X may be the same or different and represents an ionic hydrophilic moiety. Each Z may be the same or different and represents one or more counterions of the ionic hydrophilic moiety. n is 1 to 3.) Compound I represented by the formula is also included.

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

[0252] Compound I has the following formula:

Chemical formula

[0253] Compound I has the following formula II:

Chemical formula

[0254] As the compound II, for example, the following compounds are preferred.

Chemical formula

[0255] Compound I is represented by the following formula III:

Chemical formula

[0256] As the compound III, for example, the following compounds are preferable.

Chemical formula

[0257] Even when the above 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 only tetrafluoroethylene or tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene in an aqueous medium having a pH of 4.0 or more in the presence of a hydrocarbon surfactant and a polymerization initiator to obtain a TFE-based polymer. Conventionally, since a polymerization initiator showing acidity has been used in the polymerization step for producing a TFE-based polymer, the pH of the aqueous medium used in the polymerization was less than 4.0. As a result of intensive studies by the present inventors, it was surprisingly found that by setting the pH of the aqueous medium used in the polymerization to 4.0 or more, the stability of the polymerization is improved and a TFE-based polymer having a high molecular weight can be produced. In the above production method, only tetrafluoroethylene or tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene are polymerized in an aqueous medium having a pH of 4.0 or more. The above pH may be 4.0 or more, preferably more than 4.0, more preferably 4.5 or more, still more preferably 5.0 or more, still more preferably 5.5 or more, particularly preferably 6.0 or more, particularly preferably 6.5 or more, particularly preferably 7.0 or more, particularly preferably 7.5 or more, particularly preferably 8.0 or more. The upper limit value of the above pH is not particularly limited, but may be, for example, 13.0 or less. From the viewpoint of corrosion of the polymerization tank, it is preferably 12.0 or less, more preferably 11.5 or less, still more preferably 11.0 or less. The above pH can be measured by a pH meter.

[0258] The polymer composition of the present disclosure can also be obtained by a process that, even when not using the specific hydrocarbon surfactant described above, polymerizes tetrafluoroethylene alone or tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene in an aqueous medium in the presence of an anionic hydrocarbon surfactant and a polymerization initiator, and the hydrocarbon surfactant includes a salt of the hydrocarbon surfactant. In other words, at least a part of the anionic hydrocarbon surfactant in the polymerization step is in the form of a salt. As a result of intensive studies by the present inventors, surprisingly, it has been found that when the anionic hydrocarbon surfactant includes a salt of the anionic hydrocarbon surfactant, the stability of the polymerization is improved and a TFE-based polymer having a large molecular weight can be produced. This is presumably because the water solubility of the anionic surfactant is improved by including the salt, making it easier to exhibit emulsifying performance. The anionic hydrocarbon surfactant will be described later. That the anionic hydrocarbon surfactant includes a salt of the hydrocarbon surfactant can be confirmed by measuring the conductivity. In the above production method, it is preferable that the concentration of the salt of the anionic hydrocarbon surfactant is 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more, and most preferably 95% by mass or more with respect to the total mass of the anionic hydrocarbon surfactant. The ratio of the salt can be measured by the solution concentration and the conductivity. In the above production method, it is more preferable that the hydrocarbon surfactant is a carboxylic acid type hydrocarbon surfactant. The hydrocarbon surfactant does not contain fluorine. In the salt of the anionic hydrocarbon surfactant, the cation (excluding the hydrogen atom) that replaces the hydrogen atom of the acid is, for example, a metal atom, NR y 4(R yis each independently H or an organic group (preferably an organic group not containing fluorine), and may be the same or different, and may be an imidazolium having a substituent, a pyridinium having a substituent, or a phosphonium having a substituent. The above R y is preferably H or an alkyl group, more preferably H or an alkyl group having 1 to 10 carbon atoms, and still more preferably H or an alkyl group having 1 to 4 carbon atoms. As the above cation in the salt of the anionic hydrocarbon surfactant, a metal atom or NR y 4 is preferred, NR y 4 is more preferred, and NH4 is still more preferred. Since the conductivity changes greatly with the influence of temperature, using a thermostat, keep the sample solution temperature at 25 °C, and make the temperature of the cell of the pH meter the same, and then measure the conductivity.

[0259] The polymer composition of the present disclosure can be preferably 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 decomposition agent of a polymerization initiator. The above addition step is carried out during the step of performing the above emulsion polymerization in an aqueous medium. By adding a radical scavenger or a decomposition agent of a polymerization initiator, the radical concentration during polymerization can be adjusted. From the viewpoint of reducing the radical concentration, a radical scavenger is preferred.

[0260] As the above radical scavenger, a compound that does not have a restart ability after addition or chain transfer to free radicals in the polymerization system is used. Specifically, a stable radical that easily undergoes a chain transfer reaction with a primary radical or a growing radical and then does not react with a monomer, or a compound having a function of easily undergoing an addition reaction with a primary radical or a growing radical to generate a stable radical is used. What is generally called a chain transfer agent is characterized by its activity by the chain transfer constant and the restart efficiency. Among the chain transfer agents, those with a restart efficiency of almost 0% are called radical scavengers. The above radical scavenger can also be, for example, a compound having a chain transfer constant with TFE at the polymerization temperature greater than the polymerization rate constant and a restart efficiency of substantially 0%. "The restart efficiency is substantially 0%" means that the generated radicals are converted into stable radicals by the radical scavenger. Preferably, it is a compound having a chain transfer constant (Cs) with TFE at the polymerization temperature (= chain transfer rate constant (kc) / polymerization rate constant (kp)) greater than 0.1. More preferably, the above compound has a chain transfer constant (Cs) of 0.5 or more, still more preferably 1.0 or more, even more preferably 5.0 or more, and particularly preferably 10 or more.

[0261] As the above radical scavenger in the present disclosure, for example, at least one selected from the group consisting of aromatic hydroxy compounds, aromatic amines, N,N-diethylhydroxylamine, quinone compounds, terpenes, thiocyanates, and cupric chloride (CuCl2) is preferred. Examples of the aromatic hydroxy compound include unsubstituted phenol, polyhydric phenol, salicylic acid, m- or p-salicylic acid, gallic acid, naphthol, and the like. Examples of the above unsubstituted phenol include o-, m- or p-nitrophenol, o-, m- or p-aminophenol, p-nitrosophenol, and the like. Examples of the polyhydric phenol include catechol, resorcinol, hydroquinone, pyrogallol, phloroglucin, naphthoresorcinol, and the like. Examples of the aromatic amines include o-, m- or p-phenylenediamine, benzidine, and the like. Examples of the above quinone compound include o-, m- or p-benzoquinone, 1,4-naphthoquinone, alizarin, and the like. Examples of the thiocyanate include ammonium thiocyanate (NH4SCN), potassium thiocyanate (KSCN), sodium thiocyanate (NaSCN), and the like. Among the above radical scavengers, aromatic hydroxy compounds are preferred, unsubstituted phenol or polyhydric phenol is more preferred, and hydroquinone is still more preferred.

[0262] From the viewpoint of reducing the standard specific gravity, the addition amount of the above radical scavenger is preferably an amount corresponding to 3 to 500% (molar basis) of the polymerization initiator concentration. A more preferable lower limit is 5% (molar basis), still more preferably 8% (molar basis), still more preferably 10% (molar basis), still more preferably 15% (molar basis), particularly preferably 20% (molar basis), especially preferably 25% (molar basis), particularly preferably 30% (molar basis), and particularly preferably 35% (molar basis). A more preferable upper limit is 400% (molar basis), still more preferably 300% (molar basis), still more preferably 200% (molar basis), and particularly preferably 100% (molar basis).

[0263] As the decomposer of the polymerization initiator, any compound that can decompose the polymerization initiator used may be used. For example, at least one selected from the group consisting of sulfites, bisulfites, bromates, diimines, diimine salts, oxalic acid, oxalates, copper salts, and iron salts is preferable. Examples of the sulfite include sodium sulfite and ammonium sulfite. Examples of the copper salt include copper(II) sulfate, and examples of the iron salt include iron(II) sulfate. The addition amount of the above decomposer of the polymerization initiator is added in the range of 25 to 300% by mass based on the amount of the oxidizing agent combined as the polymerization initiator (a redox initiator described later). Preferably, it is 25 to 150% by mass, and more preferably 50 to 100% by mass. From the viewpoint of reducing the standard specific gravity, the addition amount of the above decomposer of the polymerization initiator is preferably an amount corresponding to 3 to 500% (molar basis) of the polymerization initiator concentration. A more preferable lower limit is 5% (molar basis), still more preferably 8% (molar basis), still more preferably 10% (molar basis), still more preferably 13% (molar basis), and still more preferably 15% (molar basis). A more preferable upper limit is 400% (molar basis), still more preferably 300% (molar basis), still more preferably 200% (molar basis), and particularly 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-based polymer formed in the aqueous medium is 5% by mass or more. More preferably, it is when the concentration is 10% by mass or more. Also, it is preferably added when the concentration of the TFE-based polymer formed in the aqueous medium is 40% by mass or less. More preferably, it is when the concentration is 35% by mass or less, and still more preferably, it is when the concentration is 30% by mass or less.

[0265] The above addition step may be a step of continuously adding at least one selected from the group consisting of a radical scavenger and a decomposer of a polymerization initiator. Continuously adding at least one selected from the group consisting of a radical scavenger and a decomposer of a polymerization initiator means, for example, adding at least one selected from the group consisting of a radical scavenger and a decomposer of a polymerization initiator not all at once, but over time, continuously or in portions.

[0266] The above polymerization step may be one in which tetrafluoroethylene is polymerized in the presence of a nucleating agent.

[0267] As the above nucleating agent, for example, it is preferably at least one selected from the group consisting of fluoropolyethers, nonionic surfactants, and chain transfer agents. In this case, the above 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-based surfactant and the above nucleating agent.

[0268] As the above fluoropolyether, perfluoropolyether is preferred.

[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] As the above fluoropolyether, a fluoropolyether acid or its salt is preferable. The above 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 acid or its salt, a salt of the fluoropolyether acid is preferable, an ammonium salt of the fluoropolyether acid is more preferable, and an ammonium salt of the fluoropolyether carboxylic acid is still more preferable.

[0271] The above fluoropolyether acid or its salt 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] As the above fluoropolyether acid or its salt, the following formula: CF3-CF2-CF2-O(-CFCF3-CF2-O-) n CFCF3-COOH, CF3-CF2-CF2-O(-CF2-CF2-CF2-O-) n -CF2-CF2COOH, or HOOC-CF2-O(-CF2-CF2-O-) n -(-CF2-O-) m CF2COOH (In the formula, m and n are the same as above.) It is preferably a compound represented by these or a salt thereof.

[0273] These structures have been studied by Kasai in J. Appl. Polymer Sci., 57, 797 (1995). As disclosed herein, such fluoropolyethers can have carboxylic acid groups or their salts at one or both ends. Similarly, such fluoropolyethers can have sulfonic or phosphonic acid groups or their salts at one or both ends. In addition, fluoropolyethers having 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 2 ether oxygens, preferably at least 4 ether oxygens, and even more preferably at least 6 ether oxygens. Preferably, at least 1 of the fluorocarbon groups separating the ether oxygens, more preferably at least 2 of such fluorocarbon groups, have 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 in total at least 15 carbon atoms. 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 production of a single specific fluoropolyether compound, the fluoropolyether can contain multiple compounds in various proportions within the molecular weight range relative to the average molecular weight.

[0275] The above fluoropolyether preferably has a number average molecular weight of 800 g / mol or more. Since the fluoropolyether acid or its salt may be difficult to disperse in an aqueous medium, it preferably has a number average molecular weight of 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 above fluoropolyether is preferably 5 to 3000 ppm with respect to the aqueous medium, more preferably 5 to 2000 ppm, and the even more preferably lower limit is 10 ppm and the even more preferably upper limit is 100 ppm.

[0277] Examples of the nonionic surfactant as the above nucleating agent include the nonionic surfactants described above, and a nonionic surfactant not containing fluorine is preferred. For example, as the nonionic surfactant, the following general formula (i) R 3 -O-A 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.) The compound represented by is mentioned. R 3 Preferably has 10 to 16 carbon atoms, and more preferably 12 to 16 carbon atoms. When the carbon number of R 3 is 18 or less, good dispersion stability of the aqueous dispersion is easily obtained. Also, when the carbon number of R 3 exceeds 18, the flow temperature is high and it is difficult to handle. When the carbon number of R 3 is less than 8, the surface tension of the aqueous dispersion becomes high, and the penetrability and wettability are likely to decrease.

[0278] The polyoxyalkylene chain may consist of oxyethylene and oxypropylene. It is a polyoxyalkylene chain composed of an average repeating number of 5 to 20 of oxyethylene groups and an average repeating number of 0 to 2 of oxypropylene groups, and is a hydrophilic group. The number of oxyethylene units may include either a broad or narrow unimodal distribution that is usually provided, or a broader or bimodal distribution obtained by blending. When the average repeating number of oxypropylene groups exceeds 0, the oxyethylene groups and oxypropylene groups in the polyoxyalkylene chain may be arranged in a block or random manner. From the viewpoints of the viscosity and stability of the aqueous dispersion, a polyoxyalkylene chain composed of an average repeating number of 7 to 12 of oxyethylene groups and an average repeating number of 0 to 2 of oxypropylene groups is preferable. Particularly, when A 1 has an average of 0.5 to 1.5 oxypropylene groups, it has good low foaming property and is preferable.

[0279] More preferably, R 3 is (R’)(R’’)HC-, where R’ and R’’ are the same or different linear, branched, or cyclic alkyl groups, and the total amount of carbon atoms is at least 5, preferably 7 to 17. Preferably, at least one of R’ or R’’ is a branched or cyclic hydrocarbon group.

[0280] Specific examples of the above 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(C5H 11 )(C7H 15)-O-(C2H4O)9-H and the like can be mentioned. Examples of commercially available products of the above polyoxyethylene alkyl ether include, for example, Genapol X080 (product name, manufactured by Clariant), Neugen TDS-80 (trade name), the Neugen TDS series (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with Neugen TDS-80 as an example, the Leocol TD series (manufactured by Lion Corporation) with Leocol TD-90 (trade name) as an example, the Lionol (registered trademark) TD series (manufactured by Lion Corporation), the T-Det A series (manufactured by Harcros Chemicals) with T-Det A138 (trade name) as an example, the Triton (registered trademark) 15S series (manufactured by Dow) and the like.

[0281] The above 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. This type of nonionic surfactant is also commercially available, for example, as TERGITOL TMN-6, TERGITOL TMN-10, and TERGITOL TMN-100X (all product names, manufactured by Dow Chemical Company).

[0282] Also, 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, as the polyoxyethylene alkylphenyl ether-based nonionic compound, for example, the following general formula (ii) R 4 -C6H4-O-A 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.) Compounds represented by the formula are mentioned. Specific examples of the polyoxyethylene alkylphenyl ether-based nonionic compound include Triton (registered trademark) X-100 (product name, manufactured by Dow Chemical Company) and the like.

[0283] As other nonionic surfactants, there are bifunctional block copolymers supplied as the Pluronic® R series from BASF, tridecyl alcohol alkoxylates supplied as the Iconol® TDA series from BASF Corporation, hydrocarbon-containing siloxane surfactants, preferably hydrocarbon surfactants, where when the above hydrocarbyl groups can be substituted by halogens such as fluorine, they are completely substituted by hydrogen atoms, whereby these siloxane surfactants can also be regarded as hydrocarbon surfactants, i.e., the monovalent substituents on the hydrocarbyl groups are hydrogen.

[0284] Also, in the above production method, in addition to the above specific hydrocarbon-based surfactant and other compounds having surfactant properties used as desired, additives can be used to stabilize each compound. Examples of the above additives include buffers, pH adjusters, stabilization aids, dispersion stabilizers, and the like.

[0285] As the stabilization aid, paraffin wax, fluorinated oil, fluorinated solvent, silicone oil, etc. are preferable. The stabilization aid may be used alone or in combination of two or more. As the stabilization aid, paraffin wax is more preferable. The paraffin wax may be liquid, semi-solid, or solid at room temperature, but saturated hydrocarbons having 12 or more carbon atoms are preferable. The melting point of the paraffin wax is usually preferably 40 to 65 °C, more preferably 50 to 65 °C.

[0286] The usage amount of the stabilization aid is preferably 0.1 to 12% by mass, more preferably 0.1 to 8% by mass based on the mass of the aqueous medium used. The stabilization aid is desirably sufficiently hydrophobic and completely separated from the TFE-based polymer aqueous emulsion after the emulsion polymerization of TFE so as not to become a contaminating component.

[0287] In the above manufacturing method, the emulsion polymerization can be carried out by charging an aqueous medium, the above hydrocarbon surfactant, monomers, and, if necessary, other additives 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 a polymerization initiator to initiate the polymerization reaction. After the start of the polymerization reaction, monomers, a polymerization initiator, a chain transfer agent, the above surfactant, etc. may be additionally added according to the purpose. The above hydrocarbon surfactant may be added after the polymerization reaction has started.

[0288] In the above emulsion polymerization, the polymerization temperature and the polymerization pressure are appropriately determined according to the type of monomers used, the molecular weight of the target TFE-based polymer, and the reaction rate. Usually, the polymerization temperature is 5 to 150 °C, preferably 10 °C or higher, more preferably 30 °C or higher, still more preferably 50 °C or higher. Also, it is more preferably 120 °C or lower, and still more preferably 100 °C or lower. The polymerization pressure is 0.05 to 10 MPaG. The polymerization pressure is more preferably 0.3 MPaG or higher, and still more preferably 0.5 MPaG or higher. Also, it is more preferably 5.0 MPaG or lower, and still more preferably 3.0 MPaG or lower. In particular, from the viewpoint of improving the yield, it is preferably 1.0 MPaG or higher, more preferably 1.2 MPaG or higher, still more preferably 1.5 MPaG or higher, even more preferably 1.8 MPaG or higher, and particularly preferably 2.0 MPaG or higher.

[0289] In the above emulsion polymerization, the hydrocarbon surfactant is preferably added when the concentration of the TFE-based polymer formed in the aqueous medium is less than 0.60% by mass. More preferably, the above concentration is 0.50% by mass or less, still 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 most preferably added together with the start of polymerization. The above concentration is the concentration with respect to the total of the aqueous medium and the TFE-based polymer. In addition, in the above emulsion polymerization, the amount of the hydrocarbon surfactant at the start of polymerization is preferably 1 ppm or more with respect to the aqueous medium. The amount of the hydrocarbon surfactant at the start of polymerization is preferably 10 ppm or more, more preferably 50 ppm or more, still more preferably 100 ppm or more, and even more preferably 200 ppm or more. The upper limit is not particularly limited, but for example, it is preferably 100,000 ppm, and more preferably 50,000 ppm. By the amount of the hydrocarbon surfactant at the start of polymerization being within the above range, an aqueous dispersion with a smaller average primary particle diameter and better stability can be obtained.

[0290] The above polymerization initiator is not particularly limited as long as it can generate radicals in the above polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Further, polymerization can also be initiated as a redox in combination with a reducing agent or the like. The concentration of the above polymerization initiator is appropriately determined according to the type of monomer, the molecular weight of the target TFE-based polymer, and the reaction rate.

[0291] As the above 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. For example, dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate and di-sec-butyl peroxydicarbonate, peroxy esters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate, and dialkyl peroxides such as di-t-butyl peroxide are representative examples.

[0293] The water-soluble radical polymerization initiator may be a known water-soluble peroxide. For example, ammonium salts, potassium salts, sodium salts of persulfuric acid, perboric acid, perchloric acid, phosphoric acid, percarbonic acid, etc., t-butyl permaleate, t-butyl hydroperoxide, etc. may be mentioned. Reducing agents such as sulfites and sulfites may also be included, and the amount used may be 0.1 to 20 times that of the peroxide.

[0294] For example, when performing polymerization at a low temperature of 30 °C or lower, it is preferable to use a redox initiator that combines an oxidizing agent and a reducing agent as the polymerization initiator. Examples of the oxidizing agent include persulfates, organic peroxides, potassium permanganate, manganese triacetate, ammonium cerium nitrate, bromates, etc. Examples of the reducing agent include sulfites, bisulfites, bromates, diimines, oxalic acid, etc. Examples of the persulfate include ammonium persulfate and potassium persulfate. Examples of the sulfite include sodium sulfite and ammonium sulfite. In order to increase the decomposition rate of the initiator, it is also preferable to add a copper salt or an iron salt to the combination of the redox initiator. Examples of the copper salt include copper(II) sulfate, and examples of the iron salt include iron(II) sulfate.

[0295] As the above redox initiator, it is preferable that the oxidizing agent is permanganic acid or its salt, persulfate, manganese triacetate, cerium(IV) salt, or bromic acid or its salt, and the reducing agent is dicarboxylic acid or its salt, or diimine. More preferably, the oxidizing agent is permanganic acid or its salt, persulfate, or bromic acid or its salt, and the reducing agent is dicarboxylic acid or its salt.

[0296] Examples of the above redox initiator include combinations such as potassium permanganate / oxalic acid, potassium permanganate / ammonium oxalate, manganese triacetate / oxalic acid, manganese triacetate / ammonium oxalate, ammonium cerium nitrate / oxalic acid, ammonium cerium nitrate / ammonium oxalate, etc. When using a redox initiator, either an oxidizing agent or a reducing agent may be charged into the polymerization tank in advance, and then the other may be added continuously or intermittently to initiate the polymerization. For example, when using potassium permanganate / ammonium oxalate, it is preferable to charge ammonium oxalate into the polymerization tank and continuously add potassium permanganate thereto. In addition, in the redox initiator of this specification, when "potassium permanganate / ammonium oxalate" is described, it means a combination of potassium permanganate and ammonium oxalate. The same applies to other compounds. As the above redox initiator, it is preferable to use an oxidizing agent or a reducing agent that can make the pH of the aqueous solution of the redox initiator 4.0 or higher. The above aqueous solution of the redox initiator means an aqueous solution with a concentration of 0.50% by mass of the oxidizing agent or an aqueous solution with a concentration of 0.50% by mass of the reducing agent. That is, it is sufficient that the pH of at least one of the aqueous solution with a concentration of 0.50% by mass of the oxidizing agent and the aqueous solution with a concentration of 0.50% by mass of the reducing agent is 4.0 or higher, and it is preferable that the pH of both the aqueous solution with a concentration of 0.50% by mass of the oxidizing agent and the aqueous solution with a concentration of 0.50% by mass of the reducing agent is 4.0 or higher. The pH of the above aqueous solution of the redox initiator (aqueous solution with a concentration of 0.50% by mass of the oxidizing agent or aqueous solution with a concentration of 0.50% by mass of the reducing agent) is more preferably 5.0 or higher, further preferably 5.5 or higher, and particularly preferably 6.0 or higher, respectively.

[0297] The above 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 above salt is more preferably at least one selected from the group consisting of persulfates, permanganates, cerium(IV) salts, and bromates, further preferably a permanganate, and particularly preferably potassium permanganate. In addition, the reducing agent that is the above salt is more preferably at least one selected from the group consisting of oxalates, malonates, succinates, glutarates, and bromates, further preferably an oxalate, and particularly preferably ammonium oxalate.

[0298] Specific examples of the redox initiator preferably include at least one selected from the group consisting of potassium permanganate / ammonium oxalate, potassium bromate / ammonium sulfite, manganese triacetate / ammonium oxalate, and ammonium cerium nitrate / ammonium oxalate, and more preferably at least one selected from the group consisting of potassium permanganate / ammonium oxalate, potassium bromate / ammonium sulfite, and ammonium cerium nitrate / ammonium oxalate.

[0299] By using a redox initiator in the polymerization step, the molecular weight of the obtained TFE-based polymer can be increased. Therefore, the SSG can be decreased, and the polymer can be made stretchable. In addition, by using a redox initiator in the polymerization step, the number of particles of the TFE-based polymer formed in the aqueous dispersion can be increased. Also, the yield of the TFE-based polymer can be increased. When using a redox initiator, the oxidizing agent and the reducing agent may be added together at the beginning of polymerization, or the reducing agent may be added together at the beginning of polymerization and the oxidizing agent may be added continuously, or the oxidizing agent may be added together at the beginning of polymerization and the reducing agent may be added continuously, or both the oxidizing agent and the reducing agent may be added continuously. When using a redox initiator as the polymerization initiator, the addition amount of the oxidizing agent is preferably 5 to 10000 ppm, more preferably 10 to 1000 ppm, and the addition amount of the reducing agent is preferably 5 to 10000 ppm, more preferably 10 to 1000 ppm, based on the aqueous medium. In addition, when using a redox initiator in the polymerization step, the polymerization temperature is preferably 100°C or lower, more preferably 95°C or lower, and still more preferably 90°C or lower. Also, it is preferably 10°C or higher, more preferably 20°C or higher, and still more preferably 30°C or higher.

[0300] The addition amount of the polymerization initiator is not particularly limited, but it may be added all at once, sequentially, or continuously at the initial stage of polymerization in an amount such that the polymerization rate does not significantly decrease (for example, several ppm with respect to the water concentration). The upper limit is in the range where the reaction temperature may be increased while removing the heat of polymerization reaction from the apparatus surface, and a more preferable upper limit is in the range where the heat of polymerization reaction can be removed from the apparatus surface. More specifically, for example, 1 ppm or more is preferable with respect to the aqueous medium, 10 ppm or more is more preferable, and 50 ppm or more is still more preferable. Also, 100000 ppm or less is preferable, 10000 ppm or less is more preferable, and 5000 ppm or less is still more preferable.

[0301] The above aqueous medium is a reaction medium for carrying out polymerization and means a liquid containing water. The above 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 alcohol, ether, ketone, and / or a fluorine-containing organic solvent having a boiling point of 40°C or lower.

[0302] In the above emulsion polymerization, further, a known chain transfer agent can be added according to the purpose to adjust the polymerization rate and molecular weight.

[0303] Examples of the above 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] A bromine compound or an iodine compound may be used as the chain transfer agent. Examples of the polymerization method using a bromine compound or an iodine compound include, for example, a method of polymerizing a fluoromonomer in an aqueous medium in the substantial absence of oxygen in the presence of a bromine compound or an iodine compound (iodine transfer polymerization method). Representative examples of the bromine compound or iodine compound to be used include, for example, the general formula: R a Ix Br y (wherein x and y are each an integer from 0 to 2 and satisfy 1 ≦ x + y ≦ 2, and 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). Compounds represented by the formula are exemplified. 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 the iodine compound include 1,3-diiodoperfluoropropane, 2-iodoperfluoropropane, 1,3-diiodo-2-chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo-n-propane, CF2Br2, BrCF2CF2Br, CF3CFBrCF2Br, CFClBr2, BrCF2CFClBr, CFBrClCFClBr, BrCF2CF2CF2Br, BrCF2CFBrOCF3, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobuten-1, 2-bromo-4-iodoperfluorobuten-1, monoiodomonobromo substituents of benzene, diiodomonobromo substituents, and (2-iodoethyl) and (2-bromoethyl) substituents, etc. These compounds may be used alone or in combination with each other.

[0306] Among these, from the viewpoints of polymerization reactivity, crosslinking reactivity, availability, etc., it is preferable to use 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, and 2-iodoperfluoropropane.

[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 the fluoromonomer supplied.

[0308] The above chain transfer agent may be added all at once into the reaction vessel before the start of polymerization, or may be added all at once after the start of polymerization, or may be added in a plurality of divided portions during polymerization, or may be continuously added during polymerization.

[0309] An aqueous dispersion of a TFE-based polymer can be obtained by the above emulsion polymerization. The above aqueous dispersion usually contains a TFE-based polymer, the compound (1) and / or (2), and an aqueous medium. The solid content concentration of the above aqueous dispersion is not limited, and may be, for example, 1.0 to 70% by mass. The solid content concentration is preferably 8.0% by mass or more, more preferably 10.0% by mass or more, and preferably 60.0% by mass or less, more preferably 50.0% by mass or less. In the above production method, the adhesion amount is preferably 3.0% by mass or less, more preferably 2.0% by mass or less, more preferably 1.0% by mass or less, still 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 a known method such as suspension polymerization, emulsion polymerization, solution polymerization, etc. Among them, 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 performing coagulation on an aqueous dispersion of a TFE-based polymer, usually, an aqueous dispersion obtained by polymerization such as a polymer latex is diluted with water to a polymer concentration of 10 to 25% by mass (preferably a polymer concentration of 10 to 20% by mass). In some cases, after adjusting the pH to neutral or alkaline, stirring is performed more vigorously than during the reaction in a container equipped with a stirrer. The above coagulation may be carried out while adding a water-soluble organic compound such as methanol or acetone, an inorganic salt such as potassium nitrate or ammonium carbonate, or an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid as a coagulant. The above coagulation may also be carried out continuously using an in-line mixer or the like.

[0312] The drying (heat treatment) in step (C) is usually carried out using means such as vacuum, high frequency, or hot air while keeping the wet powder in a state where it does not flow much, preferably in a static state. Friction between powders, especially at high temperatures, generally has an unfavorable effect on fine powder type fibrillatable polymers. This is because particles composed of this type of fibrillatable polymer have the property of easily fibrillating even by a small shear force and losing the original stable particle structure state.

[0313] The drying temperature in step (C) is preferably 130 °C or higher, more preferably 140 °C or higher, still more preferably 150 °C or higher, still more preferably 160 °C or higher, still more preferably 180 °C or higher, still more preferably 200 °C or higher, particularly preferably 220 °C or higher, and preferably 300 °C or lower, more preferably 280 °C or lower, still more preferably 250 °C or lower, in terms of more efficiently removing moisture and fluorine-containing compounds. When using vacuum, drying at a low temperature such as 60 °C or higher, 70 °C or higher, 80 °C or higher, 90 °C or higher is also preferable.

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

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

[0316] The drying in step (C) can be carried out using an electric furnace or a steam furnace. For example, an electric furnace such as a parallel flow box-type electric furnace, a vented box-type electric furnace, a vented conveyor-type electric furnace, a band electric furnace, a radiation conveyor-type electric furnace, a fluidized bed electric furnace, a vacuum electric furnace, a stirred electric furnace, an air flow type electric furnace, a hot air circulation type electric furnace, etc., or a steam furnace corresponding to the above (a device obtained by replacing the electric furnace in the device name of each of the above electric furnaces with a steam furnace) can be used. In terms of more efficiently removing moisture and fluorine-containing compounds, a parallel flow box-type electric furnace, a vented box-type electric furnace, a vented conveyor-type electric furnace, a band electric furnace, a fluidized bed electric furnace, a hot air circulation type electric furnace, and a steam furnace corresponding to the above (a device obtained by replacing the electric furnace in the device name of each of the above electric furnaces with a steam furnace) are preferred.

[0317] The drying in step (C) is preferably carried out by arranging the wet powder in a breathable container on the bottom surface and / or side surface in terms of more efficiently removing moisture and fluorine-containing compounds. The breathable container on the bottom surface and / or side surface may be any that can withstand the drying temperature, but is preferably made of a metal such as stainless steel. As the air-permeable container on the bottom surface and / or side surface, a tray (bat) having air permeability on the bottom surface and / or side surface is preferable, and a tray (mesh tray) whose bottom surface and / or side surface is made of mesh is more preferable. The mesh is preferably either a woven net or a punching metal. The mesh opening is preferably 2000 μm or less (10 mesh or more according to ASTM standard), more preferably 595 μm or less (30 mesh or more), still 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 especially preferably 74 μm or less (200 mesh or more). Also, 25 μm or more (500 mesh or less) is preferable. Examples of the weaving method when the mesh is a woven net include plain weave, twill weave, plain basket weave, and twill basket weave. When the mesh is a punching metal, the aperture ratio is preferably 10% or more, more preferably 20% or more, and still more preferably 30% or more. Also, 95% or less is preferable.

[0318] In step (C), the amount of the wet powder disposed is preferably 10 g / cm 2 or less in terms of more efficiently removing moisture and fluorine-containing compounds, more preferably 8 g / cm 2 or less, still more preferably 5 g / cm 2 or less, particularly preferably 3 g / cm 2 or less, and preferably 0.01 g / cm 2 or more, more preferably 0.05 g / cm 2 or more, and still more preferably 0.1 g / cm 2 or more.

[0319] In step (C), the water content of the wet powder to be dried is preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and preferably 150% by mass or less, more preferably 100% by mass or less, in terms of more efficiently removing water and fluorine-containing compounds from the wet powder.

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

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

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

[0323] The mixing in step (D) can be carried out by a dry mixing method. In terms of improving the powder fluidity, it is preferable to adopt a mixing method with weak shearing force so as to suppress the fibrillation of the fibrillatable polymer. For example, it is preferable to adopt a mixing method without using a stirring blade, such as air flow mixing or mixing using a V blender.

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

[0325] The present disclosure also provides a binder for electrochemical devices consisting essentially of only a polymer composition. The polymer composition includes a fibrillatable polymer, a thermoplastic polymer, and at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2) (hereinafter, also referred to as the binder (1) of the present disclosure). General formula (1): (H-(CF2) m-1 -COO) p M 1 (In the formula, m is 4 to 20. M 1 is H, a metal atom, NR 5 4 (R 5 may be the same or different, and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF2) n -SO3) q M 2 (In the formula, n is 4 to 20. M 2 is H, a metal atom, NR 5 4 (R 5 is the same as above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. q is 1 or 2.)

[0326] The present disclosure also provides a binder for an electrochemical device consisting essentially of only a polymer composition, wherein the polymer composition includes a fibrillatable polymer and a thermoplastic polymer, and the thermal instability index (TII) of the fibrillatable polymer is 10 or more. (Hereinafter, it is also referred to as the binder (2) of the present disclosure.)

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

[0328] By including a specific polymer composition, the binder of the present disclosure can improve the Coulombic efficiency of an electrochemical device. Also, a paste sheet can be produced even with a small addition amount. Further, since a paste sheet excellent in adhesion to a substrate such as a metal foil can be obtained, the paste sheet and the substrate can be adhered without increasing the density of the paste layer (without pressure consolidation), and processing can be performed under a wider range of molding conditions. When the binder of the present disclosure is in the form of a powder, its fluidity can also be improved. Since the binder of the present disclosure can also be used dry, it is not necessary to use a large amount of a dispersion medium such as water or an organic solvent, and a wide range of electrode active materials and solid electrolytes to be combined can be selected, which is advantageous in the production process. Also, the processes and costs associated with the use of a dispersion medium can be reduced. Furthermore, since the binder of the present disclosure has excellent binding force to 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 as the polymer composition of the present disclosure described above can be used, and the preferred embodiments are also the same.

[0330] The binder of the present disclosure consists essentially of only the above polymer composition. Thereby, the effects of the above polymer composition can be significantly exerted. Consisting essentially of only the above polymer composition means that the content of the above polymer composition is 95.0% by mass or more based on the binder. The content of the above polymer composition is preferably 98.0% by mass or more, more preferably 99.0% by mass or more, still 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, based on the above binder. It is also preferable that the binder of the present disclosure consists only of the above polymer composition.

[0331] The binder of the present disclosure preferably contains substantially no organic solvent. Thereby, the processes and costs due to the use of the organic solvent can be reduced. Containing substantially no organic solvent means that the organic solvent content with respect to the above binder is 5% by mass or less. The above organic solvent content is preferably 3% by mass or less, more preferably 1% by mass or less, still 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 form of the binder of the present disclosure is preferably powder, but may be other forms than powder, for example, a dispersion or a molded body.

[0333] The binder of the present disclosure is used in electrochemical devices such as batteries and capacitors. Examples of the battery include secondary batteries such as lithium-ion batteries. The capacitor is not particularly limited, but is preferably an electrochemical capacitor. Examples of the electrochemical capacitor include an electric double layer capacitor, a hybrid capacitor, and a redox capacitor. Examples of the hybrid capacitor include a sodium ion capacitor, a lithium ion capacitor, and a magnesium ion capacitor. Among these, an electric double layer capacitor is particularly preferable.

[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 binder of the present disclosure may be used for producing an electrochemical device member, preferably a battery member. The binder of the present disclosure can be particularly suitably used as an electrode binder. The binder of the present disclosure can also be suitably used as a binder in the solid electrolyte layer of a solid secondary battery.

[0335] The present disclosure also provides an electrode mixture containing the above-described polymer composition or binder of the present disclosure and an electrode active material. When the electrode mixture of the present disclosure is used, the Coulomb efficiency of an electrochemical device can be improved. Further, even when the amount of the binder is small, the electrode active material can be retained, so that more materials for improving the characteristics of the electrochemical device such as the active material and the conductive assistant can be added. Further, since an agent sheet excellent in adhesion to a base material such as a metal foil can be obtained, the agent sheet and the base material can be adhered without increasing (consolidating) the density of the agent layer, and can be processed under wider 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 occlude and release alkali metal ions. For example, a material containing an alkali metal and at least one transition metal is preferable. Specific examples include alkali metal-containing transition metal composite oxides and alkali metal-containing transition metal phosphate compounds. Among them, as the positive electrode active material, an alkali metal-containing transition metal composite oxide that produces a high voltage is particularly preferable. Examples of the alkali metal ions include lithium ions, sodium ions, potassium ions, and the like. In a preferred embodiment, the alkali metal ions can be lithium ions. That is, in this embodiment, the alkali metal ion secondary battery is a lithium ion secondary battery.

[0338] Examples of the above alkali metal-containing transition metal composite oxides include Formula: M a Mn 2-b M 1 b O4 (In the formula, 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) represents an alkali metal-manganese spinel composite oxide (such as lithium-manganese spinel composite oxide), Formula: MNi 1-c M 2 c O2 (In the formula, 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) represents an alkali metal-nickel composite oxide (such as lithium-nickel composite oxide), or Formula: MCo 1-d M 3 d O2 (In the formula, M is at least one metal selected from the group consisting of Li, Na, and K; 0 ≦ d ≦ 0.5; M 3 is at least one metal selected from the group consisting of Fe, Ni, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge) represents an alkali metal-cobalt composite oxide (such as lithium-cobalt composite oxide). In the above, M is preferably one metal selected from the group consisting of Li, Na, and K, more preferably Li or Na, and still more preferably Li.

[0339] Among them, MCoO2, MMnO2, MNiO2, MMn2O4, MNi 0.8 Co 0.15 Al 0.05 O2, or MNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc. are preferable, and a compound represented by the following general formula (3) is preferable. 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 selected from the group consisting of Fe, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge, and (h + i + j + k) = 1.0, 0 ≦ h ≦ 1.0, 0 ≦ i ≦ 1.0, 0 ≦ j ≦ 1.5, 0 ≦ k ≦ 0.2.)

[0340] Examples of the alkali metal-containing transition metal phosphate compound include 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, 1 ≦ g ≦ 3.) Compounds represented by the formula are included. In the above, M is preferably one metal selected from the group consisting of Li, Na, and K, more preferably Li or Na, and still more preferably Li. That is, as the alkali metal-containing transition metal phosphate compound, a lithium-containing transition metal phosphate compound is preferable.

[0341] As the transition metal of the above lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferable. Specific examples include, for example, iron phosphates such as LiFePO4, Li3Fe2(PO4)3, LiFeP2O7, cobalt phosphates such as LiCoPO4, and those in which a part of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si, etc. As the above lithium-containing transition metal phosphate compound, those having an olivine-type structure are preferable.

[0342] As other positive electrode active materials, lithium-nickel-based composite oxides can be mentioned. As the above lithium-nickel-based composite oxide, the following general formula (5): Li y Ni 1-x M x O2(5) (In the formula, x is 0.01 ≦ x ≦ 0.7, y is 0.9 ≦ y ≦ 2.0, and M represents a metal atom (excluding Li and Ni)) is preferable as the positive electrode active material.

[0343] As other positive electrode active materials, MFePO4, 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. can also be mentioned. In particular, positive electrode active materials such as M2MnO3, MNi 0.5 Mn 1.5 O2 (in the formula, M is at least one metal selected from the group consisting of Li, Na, and K) are preferable in that the crystal structure does not collapse even when the secondary battery is operated at a voltage exceeding 4.4V or a voltage of 4.6V or higher. Therefore, electrochemical devices such as secondary batteries using a positive electrode material containing the positive electrode active materials exemplified above are preferable because the residual capacity hardly decreases even when stored at a high temperature, the resistance increase rate hardly changes, and the battery performance does not deteriorate even when operated at a high voltage.

[0344] As other positive electrode active materials, M2MnO3 and MM 6 O2 (wherein 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 manganate 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 contains, for example, 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 0.5 Co 0.14 Ni 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, still more preferably 0.5% by mass or more, and preferably 10% by mass or less, more preferably 8% by mass or less, still more preferably 5% by mass or less, based on the total of the above positive electrode active material and lithium phosphate.

[0347] The shapes of the particles of the positive electrode active material include those conventionally used, such as massive, polyhedral, spherical, ellipsoidal, plate-like, needle-like, columnar, etc. Further, primary particles may aggregate to form secondary particles.

[0348] The median diameter d50 of the particles of the positive electrode active material (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, still more preferably 0.8 μm or more, and most preferably 1.0 μm or more. Also, it is preferably 30 μm or less, more preferably 27 μm or less, still more preferably 25 μm or less, and most preferably 22 μm or less. If it is less than the above lower limit, high tap density products may not be obtained. If it exceeds the upper limit, it may take time for lithium diffusion within the particles, leading to problems such as a decrease in battery performance. Here, by mixing two or more types of the above positive electrode active materials having different median diameters d50, the filling property during positive electrode production can be further improved.

[0349] The above median diameter d50 is measured by a known laser diffraction / scattering particle size distribution measuring device. When using LA-920 manufactured by HORIBA as the particle size distribution meter, as the dispersion medium used for measurement, an aqueous solution of 0.1 mass% sodium hexametaphosphate is used, and after 5 minutes of ultrasonic dispersion, the measurement refractive index is set to 1.24 for measurement.

[0350] The BET specific surface area of the positive electrode active material is preferably 0.1 m 2 / g or more, more preferably 0.2 m 2 / g or more, still more preferably 0.3 m 2 / g or more, and the upper limit is preferably 50 m 2 / g or less, more preferably 40 m 2 / g or less, still more preferably 30 m 2 / g or less. If the BET specific surface area is smaller than this range, the battery performance is likely to decrease. If it is larger, it is difficult to increase the tap density, and problems may easily occur in the processability during the formation of the positive electrode active material layer. The above BET specific surface area is defined as the value measured by the nitrogen adsorption BET one-point method by the gas flow method using a nitrogen-helium mixed gas accurately adjusted so that the relative pressure value of nitrogen with respect to atmospheric pressure becomes 0.3, after performing preliminary drying on the sample at 150 °C for 30 minutes under nitrogen flow using a surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken Co., Ltd.).

[0351] The particles of the above positive electrode active material preferably mainly consist of secondary particles. The particles of the above positive electrode active material preferably contain fine particles with an average particle diameter of the secondary particles of 40 μm or less and an average primary particle diameter of 1 μm or less in an amount of 0.5 to 30.0% by volume. By containing fine particles with an average primary particle diameter of 1 μm or less, the contact area with the electrolyte becomes large, and the diffusion of lithium ions between the electrode binder and the electrolyte can be made faster, and as a result, the output performance of the battery can be improved.

[0352] For the production of the positive electrode, the above positive electrode active material may be used alone, or two or more kinds with different compositions may be used in combination in any combination or ratio. Preferred combinations in this case include combinations with ternary systems such as LiCoO2 and LiNi 0.33 Co 0.33 Mn 0.33 O2, etc., combinations with LiCoO2 and LiMn2O4 or those in which a part of this Mn is replaced with other transition metals, etc., or combinations of LiFePO4 and LiMn2O4.

[0353] The content of the above positive electrode active material is preferably 50 to 99.5% by mass, more preferably 80 to 99% by mass, of the positive electrode binder in terms of high battery capacity. Also, the content in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, 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 electric 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. For example, it includes carbonaceous materials such as lithium metal, artificial graphite, graphite carbon fiber, resin-fired carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-fired carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon; silicon-containing compounds such as silicon and silicon alloys; Li4Ti5O 12 Any one selected from these, or a mixture of two or more thereof, etc. can be mentioned. Among them, those containing at least a part of a carbonaceous material and silicon-containing compounds can be particularly preferably used.

[0355] In the present disclosure, it is preferable that the negative electrode active material used contains silicon as a constituent element. By including silicon as a constituent element, a high-capacity battery can be produced.

[0356] As the material containing silicon, silicon particles, particles having a structure in which fine particles of silicon 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 are preferable. By using these, a negative electrode mixture for a lithium ion secondary battery with higher first charge-discharge efficiency, high capacity, and excellent cycle characteristics can be obtained.

[0357] The physical properties of the particles containing silicon can be appropriately selected according to the target composite particles. For example, the average particle size is preferably 0.1 to 50 μm, more preferably 0.2 μm or more, and still more preferably 0.5 μm or more. The upper limit is more preferably 30 μm or less, and still more preferably 20 μm or less. The above average particle size is represented by the weight average particle size in the particle size distribution measurement by the laser diffraction method.

[0358] The BET specific surface area is preferably 0.5 to 100 m 2 / g, and more preferably 1 to 20 m 2 / g. If the BET specific surface area is 0.5 m 2 / g or more, there is no risk that the adhesiveness when processed into an electrode will decrease and the battery characteristics will deteriorate. Also, 100 m 2If it is / g or less, the proportion of silicon on the particle surface increases, 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] By carbon-coating the silicon-containing particles, conductivity is imparted and an improvement in battery characteristics can be seen. As methods for imparting conductivity, there are a method of mixing the silicon-containing particles with conductive particles such as graphite, a method of coating the surface of the silicon-containing particles with a carbon film, and a method of combining both. Among them, the method of coating with a carbon film is preferable, and the method of chemical vapor deposition (CVD) is more preferable.

[0360] In order to increase the capacity of the obtained electrode mixture, the content of the negative electrode active material is preferably 40 mass% or more, more preferably 50 mass% or more, and particularly preferably 60 mass% or more in the electrode mixture. The upper limit is preferably 99 mass% or less, more preferably 98 mass% or less.

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

[0362] The conductive aid is usually used in an amount of 0.01 mass% or more, preferably 0.1 mass% or more, more preferably 1 mass% or more in the electrode mixture, and usually 50 mass% or less, preferably 30 mass% or less, more preferably 15 mass% or less. 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, polyethylene oxide, and the like. It may be used alone or in combination of two or more in any combination and ratio.

[0364] The proportion of the thermoplastic resin with respect 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 is usually in the range of 3.0% by mass or less, preferably 2.5% by mass or less, more preferably 2.0% by mass or less. By adding the thermoplastic resin, the mechanical strength of the electrode can be improved. Also, if it exceeds this range, there may be problems such as a decrease in the proportion of the electrode active material in the electrode mixture and a decrease in the capacity of the battery, or an increase in the resistance between the active materials.

[0365] In the electrode mixture of the present disclosure, the content of the binder may be 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.5% by mass or more, with respect to the above electrode mixture, 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 proportion of the binder is too low, the electrode mixture active material cannot 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 it is too high, it may lead to a decrease in battery capacity and conductivity. Since the binder of the present disclosure has excellent adhesive strength, the electrode active material can be sufficiently retained even with a small content.

[0366] In the electrode binder of the present disclosure, the binder component preferably consists essentially of only the above polymer composition, and more preferably consists of only the above polymer composition. That the binder component consists essentially of only the above polymer composition means that the content of the above polymer composition in the binder component constituting the electrode binder is 95.0% by mass or more based on the above binder component. The content of the above polymer composition is preferably 98.0% by mass or more, more preferably 99.0% by mass or more, still 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 based on the above binder component.

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

[0368] The electrode binder of the present disclosure can be suitably used as an electrode binder for secondary batteries. In particular, the electrode binder of the present disclosure is suitable for lithium-ion secondary batteries. When the electrode binder of the present disclosure is used in a secondary battery, it is usually used in the form of a sheet.

[0369] The above electrode binder sheet preferably has a thickness of 300 μm or less, more preferably 250 μm or less, still 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, still more preferably 20 μm or more.

[0370] An example of a specific manufacturing method of an electrode binder sheet containing the electrode binder is shown below. The above electrode binder sheet can be obtained by a manufacturing method having a step (1) of mixing a raw material composition containing an electrode active material, a binder, and, if necessary, a conductive aid, a step (2) of shaping the raw material composition obtained in the above step (1) into a bulk shape, and a step (3) of rolling the bulk raw material composition obtained in the above step (2) into a sheet shape.

[0371] In the step of mixing the raw material composition in the above step (1), the raw material composition exists in a state without a definite form, where the electrode active material, binder, etc. are simply mixed. Specific mixing methods include methods of mixing using a drum-type mixer, a conical screw-type mixer, a single-screw kneader, a twin-screw kneader, a mix muller, a stirring mixer, a planetary mixer, a Henschel mixer, a high-speed mixer, etc.

[0372] In the above step (1), the binder mixing condition is preferably set to 3000 rpm or less. Preferably it is 10 rpm or more, more preferably 15 rpm or more, still more preferably 20 rpm or more, and also preferably in the range of 2000 rpm or less, more preferably 1500 rpm or less, still more preferably 1000 rpm or less. If it is below the above range, it will take time for mixing and affect productivity. Also, if it exceeds, fibrillation may progress excessively, and there is a risk of obtaining an electrode binder sheet with inferior strength and flexibility.

[0373] In the above step (2), forming into a bulk shape means making the raw material composition into one mass. Specific methods of forming into a bulk shape include extrusion molding, press molding, etc. Also, "bulk shape" is not particularly defined in terms of shape, and it suffices as long as it is in a state of being one mass, and forms such as rod shape, sheet shape, spherical shape, cube shape, etc. are included.

[0374] Specific rolling methods in the above step (3) include methods of rolling using a roll press, a flat plate press, a calender roll, etc.

[0375] Further, after step (3), it is also preferable to have a step (4) of applying a larger load to the obtained rolled sheet and rolling it into an even thinner sheet form. It is also preferable to repeat step (4). In this way, rather than thinning the rolled sheet all at once, by rolling it in stages little by little, the flexibility becomes better. The number of times of step (4) is preferably 2 or more and 10 or less, and more preferably 3 or more and 9 or less. As a specific rolling method, for example, a method of rotating two or a plurality of rolls and passing the rolled sheet therebetween to process it into an even thinner sheet form can be mentioned.

[0376] Also, from the viewpoint of adjusting the fibril diameter, after step (3) or step (4), it is also preferable to have a step (5) of coarsely crushing the rolled sheet and then remolding it into a bulk form and rolling it into a sheet form. It is also preferable to repeat step (5). The number of times of step (5) is preferably 1 or more and 12 or less, and more preferably 2 or more and 11 or less.

[0377] In step (5), specific methods of coarsely crushing the rolled sheet and molding it into a bulk form include a method of folding the sheet, or a method of molding it into a rod or thin film sheet form, a method of chipping, etc. In the present disclosure, "coarsely crushing" means changing the form of the rolled sheet obtained in step (3) or step (4) into another form in order to roll it into a sheet form in the next step, and includes cases such as simply folding the rolled sheet.

[0378] Also, after step (5), step (4) may be performed, or may be performed repeatedly. Also, uniaxial stretching or biaxial stretching may be performed in steps (2) to (3), (4), and (5). Also, the fibril diameter can be adjusted depending on the degree of coarsely crushing in step (5).

[0379] In the above step (3), (4) or (5), the rolling rate is preferably 10% or more, more preferably 20% or more, and is preferably in the range of 80% or less, more preferably 65% or less, and even more preferably 50% or less. If it is below the above range, it will take time as the number of rolling passes increases, affecting productivity. If it exceeds the range, fibrillation may progress excessively, resulting in an electrode binder sheet with inferior strength and flexibility. Here, the rolling rate refers to the reduction rate of the thickness after processing with respect to the thickness of the sample 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 where the load is applied during rolling.

[0380] The above electrode binder sheet Step (a): mixing a powder component (such as an electrode active material) and a binder to form an electrode binder; Step (b): calendaring or extrusion molding the electrode binder to produce a sheet and The mixing in step (a) (a1) a step of homogenizing the powder component and the binder into a powder; (a2) a step of mixing the powdery raw material mixture obtained in step (a1) to prepare an electrode binder It can also be preferably manufactured by a manufacturing method characterized by including.

[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 PTFE particles becomes loose and more sensitive to mechanical shear. At temperatures above 30 °C, more advanced fibrillation occurs.

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

[0383] The above step (a2) is preferably carried out at a temperature of 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 calendaring or extrusion in the above step (b) is carried out at a temperature between 30°C and 150°C, preferably between 35°C and 120°C, and more preferably between 40°C and 100°C.

[0384] The mixing in the above step (a) is preferably carried out while applying a shearing force. As specific mixing methods, there are methods of mixing using a drum-type mixer, a conical screw-type mixer, a single-screw kneader, a twin-screw kneader, a mix muller, a stirring mixer, a planetary mixer, a Henschel mixer, a high-speed mixer, etc.

[0385] The mixing conditions may be appropriately set for the rotation speed and the mixing time. For example, the rotation speed is preferably set to 15000 rpm or less. Preferably it is 10 rpm or more, more preferably 50 rpm or more, and even more preferably 100 rpm or more. Also, it is preferably in the range of 12000 rpm or less, more preferably 10000 rpm or less, and even more preferably 8000 rpm or less. If it is below the above range, it will take time for mixing and affect productivity. Also, if it exceeds the range, fibrillation may progress excessively, resulting in an electrode binder sheet with poor strength. In step (a1), it is preferable to carry out the process with a shearing force weaker than that in step (a2). Also, in step (a1), it is desirable to carry out the process in a shorter time than in step (a2).

[0386] In the above step (a2), it is preferable that the raw material composition does not contain a liquid solvent, but a small amount of lubricant may be used. That is, a lubricant may be added to the powdery raw material mixture obtained in the above 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-based 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 the deterioration of the electrochemical device. The water content is more preferably 500 ppm or less.

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

[0390] When using the above lubricant, 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 to be subjected to step (a1).

[0391] The above raw material composition preferably contains substantially no liquid medium. In the conventional method for forming an electrode binder, it was common to prepare a slurry in which powder, which is an electrode binder component, was dispersed using a solvent in which a binder was dissolved, and to prepare an electrode binder sheet by applying and drying the slurry. In this case, a solvent for dispersing or dissolving the binder is used. However, solvents that can dissolve the conventionally commonly used binder resin are limited to specific solvents such as N-methylpyrrolidone. They have high polarity, and processes and costs are incurred due to the use of solvents because they go through a drying process. In addition, since these react with electrolytes such as electrolytic solutions and solid electrolytes to deteriorate the electrolytes, residual components during slurry preparation or after drying may cause a decrease in battery performance. Also, in low-polarity solvents such as heptane, the binder resins that can be dissolved are very limited, and the flash point is low, which may make handling complicated.

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

[0393] Step (b) is calendaring or extrusion. Calendaring and extrusion can be performed by well-known methods. Thereby, it can be formed into the shape of an electrode binder sheet. Step (b) preferably includes (b1) a step of forming the electrode binder obtained by the above step (a) into a bulk shape, and (b2) a step of calendaring or extrusion-molding the bulk electrode binder.

[0394] Forming into a bulk shape means making the electrode binder into one mass. Specific methods for forming into a bulk shape include extrusion molding, press molding, etc. In addition, the "bulk shape" is not particularly defined in terms of shape, and it only needs to be in a single lump state, including forms such as rod-shaped, sheet-shaped, spherical, cube-shaped, etc. The size of the above lump preferably has a diameter or the smallest side of its cross-section of 10,000 μm or more. More preferably, it is 20,000 μm or more.

[0395] As a specific method of calendaring or extrusion molding in the above step (b2), there is a method of rolling the electrode paste using a roll press machine, a calendar roll machine, etc.

[0396] The above step (b) is preferably carried out at 30 to 150 °C. As described above, since PTFE has a glass transition temperature near 30 °C, it easily fibrillates at 30 °C or higher. Therefore, step (b) is preferably carried out at such a temperature.

[0397] And since calendaring or extrusion is subjected to a shearing force, PTFE fibrillates thereby and forming is performed.

[0398] After step (b), it is also preferable to have a step (c) of applying a larger load to the obtained rolled sheet and rolling it into an even thinner sheet shape. It is also preferable to repeat step (c). In this way, by rolling the rolled sheet not all at once but in stages little by little, the flexibility becomes better. The number of times of step (c) is preferably 2 or more and 10 or less, and more preferably 3 or more and 9 or less. As a specific rolling method, for example, there is a method of rotating two or more rolls and passing the rolled sheet between them to process it into an even thinner sheet shape.

[0399] From the perspective of adjusting the sheet strength, it is also preferable to have a step (d) in which after step (b) or step (c), the rolled sheet is crushed and then formed into a bulk shape again and rolled into a sheet shape. It is also preferable to repeat step (d). The number of times of step (d) is preferably 1 or more and 12 or less, and more preferably 2 or more and 11 or less.

[0400] In step (d), specific methods for crushing the rolled sheet and forming it into a bulk shape include folding the rolled sheet, or forming it into a rod or thin film sheet shape, chipping, etc. In the present disclosure, "crushing" means changing the form of the rolled sheet obtained in step (b) or step (c) to another form in order to roll it into a sheet shape in the next step, and includes cases where the rolled sheet is simply folded.

[0401] Also, after step (d), step (c) may be performed or may be repeated. Also, uniaxial stretching or biaxial stretching may be performed in steps (a) to (b), (c), and (d). Also, the sheet strength can be adjusted depending on the degree of crushing in step (d).

[0402] In the above steps (b), (c) or (d), the rolling rate is preferably 10% or more, more preferably 20% or more, and also preferably 80% or less, more preferably 65% or less, and still more preferably 50% or less. If it is below the above range, it will take time as the number of rolling times increases, affecting productivity. Also, if it exceeds the range, fibrillation may progress excessively, resulting in an electrode binder sheet with inferior strength and flexibility. Here, the rolling rate refers to the reduction rate of the thickness after processing with respect to the thickness of the sample before rolling. The sample before rolling may be a bulk raw material composition or a sheet-shaped raw material composition. The thickness of the sample refers to the thickness in the direction where the load is applied during rolling. The above steps (c) to (d) are preferably carried out at 30°C or higher, more preferably 60°C or higher. Also, it is preferably carried out at 150°C or lower.

[0403] The above electrode mixture sheet can be used as an electrode mixture sheet for a secondary battery. It can be either the negative electrode or the positive electrode. In particular, the above electrode mixture sheet is suitable for a lithium-ion secondary battery.

[0404] The present disclosure also provides an electrode including the above-described 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. Further, even when the amount of the binder is small, the electrode active material can be retained, so that more materials for improving the characteristics of the electrochemical device such as the active material and the conductive assistant can be added. Further, it has excellent adhesion between the mixture sheet and a base material such as a metal foil.

[0405] The electrode of the present disclosure may include the above-described electrode mixture (preferably an electrode mixture sheet) of the present disclosure and a current collector.

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

[0407] The above positive electrode is preferably composed of a current collector and an electrode mixture sheet containing the above positive electrode active material. Examples of the material of the current collector for the positive electrode include metals such as aluminum, titanium, tantalum, stainless steel, and nickel, or metal materials such as alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly aluminum or its alloy, are preferable.

[0408] The density of the positive electrode mixture sheet is preferably 2.80 g / cm 3 or more, more preferably 3.00 g / cm 3 or more, still 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 or less, still more preferably 3.70 g / cm 3It is within the following range. If it exceeds this range, cracks may easily occur in the sheet. If it is below this range, the conductivity between the active materials may decrease, increasing the battery resistance and making it impossible to obtain high output in some cases.

[0409] The thickness of the positive electrode is not particularly limited. From the viewpoints of high capacity and high output, the thickness of the mixture layer obtained by subtracting the thickness of the metal foil of the current collector is preferably 10 μm or more, more preferably 20 μm or more, as the lower limit with respect to one side of the current collector, and is preferably 500 μm or less, more preferably 450 μm or less.

[0410] The above negative electrode is preferably composed of a current collector and an electrode mixture sheet containing the above negative electrode active material. Examples of the material of the current collector for the negative electrode include metals such as copper, nickel, titanium, tantalum, and stainless steel, or metal materials such as alloys thereof; and carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly copper, nickel, or alloys thereof, are preferable.

[0411] The density of the negative electrode mixture sheet is preferably 1.3 g / cm 3 or more, more preferably 1.4 g / cm 3 or more, still more preferably 1.5 g / cm 3 or more, and is preferably 2.0 g / cm 3 or less, more preferably 1.9 g / cm 3 or less, still more preferably 1.8 g / cm 3 It is within the following range. If it exceeds this range, cracks may easily occur in the sheet. If it is below this range, the conductivity between the active materials may decrease, increasing the battery resistance and making it impossible to obtain high output in some cases.

[0412] The thickness of the negative electrode is not particularly limited. From the viewpoints of high capacity and high output, the thickness of the mixture layer obtained by subtracting the thickness of the metal foil of the current collector is preferably 10 μm or more, more preferably 20 μm or more, as the lower limit with respect to one side of the current collector, and is preferably 500 μm or less, more preferably 450 μm or less.

[0413] Examples of the current collector shapes for the positive and negative electrodes include metal foils, expanded metals, punched metals, and foamed metals. Among these, metal foils are preferred. Note that the metal foil may be appropriately formed in a mesh shape. The thickness of the metal foil is arbitrary, but it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and usually 1 mm or less, preferably 100 μm or less, 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, the handleability may be impaired.

[0414] Also, it is 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 represented 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] Also, it is preferable that a conductive auxiliary agent is applied to the surface of the current collector from the viewpoint of reducing the electrical contact resistance between the current collector and the positive electrode active material layer. Examples of the conductive auxiliary agent include carbon and noble metals such as gold, platinum, and silver. Carbon is particularly preferable in terms of its low weight.

[0416] The positive and negative electrodes can be manufactured by conventional methods. For example, a method of laminating the above electrode mixture sheet and the current collector via an adhesive and pressing them can be mentioned.

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

[0418] The secondary battery of the present disclosure may be a secondary battery using an electrolytic solution or a solid secondary battery. In this specification, the solid secondary battery may be any secondary battery including a solid electrolyte, and may be a semi-solid secondary battery including a solid electrolyte and a liquid component as the electrolyte, or an all-solid secondary battery including only a solid electrolyte as the electrolyte.

[0419] The secondary battery using the above electrolyte can use an electrolyte, a separator, etc. used in known secondary batteries. These will be described in detail below.

[0420] As the above electrolyte, a non-aqueous electrolyte is preferably used. As the non-aqueous electrolyte, a known electrolyte salt dissolved in a known organic solvent for dissolving the electrolyte salt can be used.

[0421] The organic solvent for dissolving the electrolyte salt is not particularly limited, but known hydrocarbon solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc.; one or more fluorine-based solvents such as fluoroethylene carbonate, fluoroether, and fluorinated carbonate can be used.

[0422] Examples of the electrolyte salt include LiClO4, LiAsF6, LiBF4, LiPF6, LiN(SO2CF3)2, LiN(SO2C2F5)2, etc. Particularly, LiPF6, LiBF4, LiN(SO2CF3)2, LiN(SO2C2F5)2 or a combination thereof is preferable in terms of good cycle characteristics.

[0423] The concentration of the electrolyte salt is preferably 0.8 mol / liter or more, more preferably 1.0 mol / liter or more. The upper limit depends on the organic solvent for dissolving the electrolyte salt, but is usually 4.0 mol / liter or less.

[0424] The secondary battery using the above electrolyte preferably further includes a separator. The material and shape of the above separator are not particularly limited as long as they are stable in the electrolyte and have excellent liquid retention properties, and known ones can be used. Among them, resins, glass fibers, inorganic substances, etc. formed of materials stable to the above electrolyte are used, and it is preferable to use porous sheets or non-woven fabric-like forms having excellent liquid retention properties.

[0425] The above-mentioned solid secondary battery is preferably an all-solid-state secondary battery. The above-mentioned solid secondary battery is preferably a lithium-ion battery, and also preferably a sulfide-based solid secondary battery. The above-mentioned 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 above-mentioned 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 composition (preferably a composition sheet) containing the binder and the solid electrolyte of the present disclosure, and a solid electrolyte layer (preferably a solid electrolyte layer sheet) containing the binder and the solid electrolyte of the present disclosure are also preferred embodiments of the present disclosure.

[0426] The solid electrolyte used in the composition for solid secondary batteries may be a sulfide-based solid electrolyte or an oxide-based solid electrolyte. In particular, when using a sulfide-based solid electrolyte, there is an advantage of flexibility.

[0427] The above-mentioned sulfide-based solid electrolyte is not particularly limited, and includes 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 types can be used.

[0428] The above sulfide-based solid electrolyte preferably contains lithium. The sulfide-based solid electrolyte containing lithium is used in a solid battery that uses lithium ions as carriers, and is particularly preferable in terms of an electrochemical device having a high energy density.

[0429] The above oxide-based solid electrolyte is preferably a compound that contains oxygen atoms (O), has ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and has electronic insulation.

[0430] Specific compound examples include, for example, Li xa La ya TiO3 [xa = 0.3 to 0.7, ya = 0.3 to 0.7] (LLT), Li xb La yb Zr zb M bb mb O nb (M bb is at least one element of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, 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 of C, S, Al, Si, Ga, Ge, In, Sn, 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(However, 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 from 0 to 0.1, M ee represents a divalent metal atom. D 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 、Li3PO (4-3 / 2w) N w (w is w < 1), Li having a LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4, La having a perovskite type crystal structure 0.51 Li 0.34 TiO 2.94 、La 0.55 Li 0.35 TiO3, LiTi2P3O having a NASICON (Natrium 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 (However, 0 ≤ xh ≤ 1, 0 ≤ yh ≤ 1), Li7La3Zr2O having a garnet type crystal structure 12 (LLZ), etc. are mentioned. Also, ceramic materials obtained by substituting elements for LLZ are known. For example, for LLZ, Li 6.24 La3Zr2Al 0.24 O 11.98 、Li 6.25 Al 0.25 La3Zr2O12 or Li substituted with Ta 6.6 La3Zr 1.6 Ta 0.4 O 12 or Li substituted with Nb 6.75 La3Zr 1.75 Nb 0.25 O 12 and the like. In addition, there are also LLZ-based ceramic materials in which at least one element substitution of Mg (magnesium) and A (A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium)) is performed on LLZ. Further, phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li3PO4), LiPON in which part of the oxygen of lithium phosphate is substituted with nitrogen, LiPOD 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.) and the like. Also, LiA 1 ON (A 1 is at least one selected from Si, B, Ge, Al, C, Ga, etc.) and the like can also be preferably used. Specific examples include, for example, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2, etc.

[0431] The above oxide-based solid electrolyte preferably contains lithium. The oxide-based solid electrolyte containing lithium is used in a solid battery that uses lithium ions as carriers, and is particularly preferable in terms of an electrochemical device having a high energy density.

[0432] The above oxide-based solid electrolyte is preferably an oxide having a crystal structure. An oxide having a crystal structure is particularly preferable in terms of good Li ion conductivity. Examples of the oxide having a crystal 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, garnet type (Li7La3Zr2O 12 (LLZ), etc.). Among them, the garnet type is preferred.

[0433] The above solid secondary battery may include a separator between the positive electrode and the negative electrode. Examples of the separator include porous membranes such as polyethylene and polypropylene; and non-woven fabrics made of resins such as polypropylene, and non-woven fabrics such as glass fiber non-woven fabrics.

[0434] The above 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-described positive electrode, negative electrode, solid electrolyte layer, etc. Specifically, a cylindrical shape, a rectangular shape, a coin shape, a laminate shape, etc. can be mentioned.

[0435] The above solid secondary battery can be manufactured, for example, by laminating a positive electrode, a solid electrolyte layer sheet, and a negative electrode in this order and pressing them.

[0436] Although the embodiments have been described above, it will be understood that various changes in form and detail can be made without departing from the spirit and scope of the claims.

Examples

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

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

[0439] <Average primary particle size> Measured by dynamic light scattering method. An aqueous dispersion of fluoropolymer adjusted to a fluoropolymer solid content concentration of about 1.0 mass% was prepared and measured at 25 °C and 70 integrations using ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.). 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 that has not been heated to a temperature of 300 °C or higher, the temperature corresponding to the minimum point in the melting heat curve obtained by performing differential scanning calorimetry [DSC] at a heating rate of 10 °C / min was defined as the endothermic peak temperature. When there are two or more minimum points in one melting peak, each was defined as the endothermic peak temperature.

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

[0444] <Average aspect ratio of the 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, and 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 with air so as not to apply shear, and the fibrillatable polymer (PTFE) contained in the polymer composition was observed with an electron microscope. Image processing was performed on 100 or more randomly extracted particles, and the average aspect ratio of the fibrillatable polymer powder was determined from the average of the ratios of the major axis to the minor axis. When the average aspect ratio was 2.5 or less, it was judged that the fibrillatable polymer powder was not fibrillated.

[0446] <Thermoplastic polymer composition> 1 H-NMR analysis, 19 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 heat of fusion 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). It was 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 cumulative particle size distribution.

[0451] <Amount of fluorine-containing surfactant in PVdF and VT powders> Weigh 1 g of each powder, add 10 g (12.6 ml) of methanol, and perform ultrasonic treatment for 60 minutes to obtain an extract. The obtained extract was measured by LC / MS / MS. For the fluorine-containing compounds in the extract, measurement was carried out using a liquid chromatograph mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). The measurement instrument configuration and LC-MS measurement conditions are shown in Table 1. An aqueous solution of a fluorine-containing compound with a known concentration was used to prepare aqueous solutions with a content of 5 levels or more, and LC / MS analysis was performed on the aqueous solutions with each content. The relationship between the content and the area of the area corresponding to the content was plotted to draw a calibration curve. Using the above calibration curve, the area of the LC / MS chromatogram of the fluorine-containing compound in the extract was converted to the content of the fluorine-containing compound. Note that the detection limit in this measurement method is 10 mass ppb.

[0452]

Table 1

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

[0454] <Heat of fusion of fluoroelastomer> Using a differential scanning calorimeter (X-DSC823e manufactured by Hitachi High-Technologies Corporation), a DSC curve was obtained by heating 10 mg of the sample at 20 °C / min, and the heat of fusion was calculated from the magnitude of the melting peak (ΔH) appearing in the DSC curve.

[0455] <Glass transition temperature (Tg) of fluoroelastomer> Using a differential scanning calorimeter (manufactured by Hitachi High-Technologies Corporation, X-DSC823e), a DSC curve was obtained by heating 10 mg of the sample at a rate of 20 °C / min. 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 line at the inflection point of the DSC curve was defined as the glass transition temperature.

[0456] <Weight-average molecular weight of fluoroelastomer> It was measured by gel permeation chromatography (GPC). Using Tosoh Corporation's AS-8010, CO-8020, columns (three GMHHR-H columns connected in series), and Shimadzu Corporation's RID-10A, it was calculated from the data measured by flowing dimethylformamide (DMF) as a solvent at a flow rate of 1.0 ml / min (reference: polystyrene).

[0457] <Moisture content> The masses of about 20 g of the polymer composition before and after heating at 150 °C for 2 hours were measured and calculated according to the following formula. The sample was taken three times, each calculated, and then the average was obtained and the average value was adopted. Moisture content (mass%) = [(mass of the polymer composition before heating (g)) - (mass of the polymer composition after heating (g))] / (mass of the polymer composition before heating (g)) × 100

[0458] <Temperature at 0.1% mass loss> Approximately 10 mg of the polymer composition without a heating history at a temperature of 300 °C or higher was precisely weighed, placed in a dedicated aluminum pan, and measured by TG·DTA (simultaneous differential thermal and thermogravimetric analyzer). The temperature at 0.1% mass loss was defined as the temperature corresponding to the point where the weight decreased by 0.1 mass% when the aluminum pan was heated from 25 °C to 600 °C at a rate of 10 °C / min in an air atmosphere.

[0459] <Temperature at 1.0% mass loss> Weigh accurately about 10 mg of a polymer composition without a heating history at a temperature above 300 °C, store it in a dedicated aluminum pan, and measure it with a TG·DTA (simultaneous differential thermal and thermogravimetric analyzer). The 1.0% mass loss temperature was defined as the temperature corresponding to the point where the weight decreased by 1.0 mass% when the temperature of the aluminum pan was raised from 25 °C to 600 °C at a rate of 10 °C / min in an air atmosphere.

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

[0461] <Content of a specific compound containing fluorine> Measured under the following conditions using liquid chromatography-mass spectrometry.

[0462] 〔Method for measuring the content of the compound represented by the general formula (1)〕 Extraction from the composition Add 10 g (12.6 mL) of methanol to 1 g of the composition, perform ultrasonic treatment for 60 minutes, and extract the supernatant containing the compound represented by the general formula (1). The obtained extract was appropriately concentrated by nitrogen purging to obtain a concentrated extract.

[0463] Measurement of the content of the compound represented by the general formula (1) contained in the extract The content of the compound represented by the general formula (1) contained in the extract was determined by converting it to perfluorooctanoic acid.

[0464] Calibration curve of perfluorooctanoic acid Prepare five levels of methanol standard solutions of perfluorooctanoic acid with known concentrations of 1 ng / mL to 100 ng / mL, and measure them using a liquid chromatograph-mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). Using linear approximation from the respective sample concentrations and peak integration values, a and b were determined by the following relational expression (1). A = a×X + b (1) A: Peak area of perfluorooctanoic acid X: Concentration of perfluorooctanoic acid (ng / mL)

[0465] Measurement equipment configuration and LC-MS measurement conditions [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 the 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] Content of the compound represented by the general formula (2) having 4 or more and 20 or less carbon atoms contained in the extract Using a liquid chromatograph mass spectrometer, the compound represented by the general formula (2) having 4 or more and 20 or less carbon atoms was measured. For the extracted liquid phase, the peak area of the compound represented by the general formula (2) for each carbon number was determined using the MRM method.

[0477] MRM measurement parameters

Table 7

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

[0479] Content of the compound represented by the general formula (2) having carbon number n contained in the composition The content of the compound represented by the general formula (2) having carbon number n contained in the composition was determined by the following formula (4). YSn = XSn × 12.6 (4) YSn: Content of the compound represented by the general formula (2) having carbon number n contained in the composition (ppb relative to the TFE-based polymer) The lower limit of quantification is 10 mass ppb.

[0480] White solid A was obtained by the method described in Synthesis Example 1 of International Publication No. 2021 / 045228.

[0481] Preparation Example 1 0.273 g of lauric acid was added to 16 g of deionized water, and while stirring, 2.77 g of an aqueous ammonia solution with a concentration of 2.8% was gradually added to obtain aqueous solution C. 10 g of lauric acid was added to 100 g of deionized water, and while stirring, 25 g of an aqueous ammonia solution with a concentration of 10% was gradually added to obtain aqueous solution D. At this time, the pH was 9.6.

[0482] Production Example 1 1748 g of deionized water, 90 g of paraffin wax, aqueous solution C obtained in Preparation Example 1, and 0.5 g of ammonium oxalate were added to a 3 L SUS reactor equipped with a stirrer. The pH of the aqueous dispersion at this time was 9.0. The reactor was sealed, the inside of the system was purged with nitrogen to remove oxygen. The reactor was heated to 70 °C, 2.0 g of HFP was added, and further pressurized with TFE to 2.70 MPa. When a 0.5 mass% potassium permanganate aqueous solution was continuously charged into the reactor as a polymerization initiator, the pressure decreased and the reaction started. TFE was charged so that the reaction pressure became constant at 2.70 MPa. When 80 g of TFE was charged, stirring was stopped and the pressure was released until the reaction pressure reached atmospheric pressure. Immediately, the reactor was filled with TFE, the reaction pressure was set to 2.70 MPa, stirring was restarted, and the reaction was continued. At the same time, aqueous solution D obtained in Preparation Example 1 was continuously charged into the reactor. When 680 g of TFE was charged, stirring was stopped and the reactor was depressurized until the pressure reached atmospheric pressure. By the end of the reaction, 56.0 g of potassium permanganate aqueous solution and 26.2 g of aqueous solution D were charged. The aqueous dispersion was taken out of the reactor, cooled, the paraffin wax was separated, and a PTFE aqueous dispersion was obtained. The pH of the obtained PTFE aqueous dispersion was 8.8, the solid content concentration was 27.1 mass%, and the primary particle size was 220 nm.

[0483] The obtained PTFE aqueous dispersion was diluted with deionized water so that the solid content concentration became 13 mass%, and after being vigorously stirred and coagulated in a container equipped with a stirrer, it was separated from water by filtration to obtain a wet powder. The obtained wet powder was placed on a stainless-steel mesh tray, and the mesh tray was heat-treated in a hot air circulation electric furnace at 210 °C. After 18 hours, the mesh tray was taken out, air-cooled, and PTFE powder was obtained. The water content of the obtained PTFE powder was 0.002% by mass, the standard specific gravity was 2.170, the thermal instability index was 44, the HFP content was 0.002% by mass, the 0.1% mass loss temperature was 391 °C, and the 1.0% mass loss temperature was 491 °C. The content of the compound represented by the general formula (1) with carbon number m (4 to 20) contained in the obtained PTFE powder was 67 mass ppb, and the content of the compound represented by the general formula (2) with carbon number n (4 to 20) was less than 10 mass ppb.

[0484] Production Example 2 3580 g of deionized water and 7.56 g of white solid A were placed in a SUS reactor with a stirrer having an internal volume of 6 L. Next, while heating the contents of the reactor to 70 °C, suction was performed and at the same time purged with TFE to remove oxygen in the reactor, and the contents were stirred. After adding 0.5 g of ethane and 71 g of perfluoropropyl vinyl ether (PPVE) into the reactor, TFE was added until the pressure reached 2.4 MPaG. 306 mg of ammonium persulfate (APS) initiator dissolved in 20 g of deionized water was injected into the reactor. After the injection of the initiator, a pressure drop occurred and the start of polymerization was observed. TFE was added to the reactor to keep the pressure constant at 2.4 MPaG. After the start of polymerization, 108 mg of ammonium persulfate and 84 g of PPVE were continuously added. When the TFE consumed in the reaction reached about 1600 g, the supply of TFE was stopped, stirring was stopped, and the reaction was terminated. Then, the pressure in the reactor was exhausted until it reached normal pressure, and PFA aqueous dispersion 1 was obtained. PFA aqueous dispersion 1 was taken out of the reactor into the atmosphere and cooled to obtain PFA aqueous dispersion 2. The solid content concentration of the obtained PFA aqueous dispersion 2 was 30.5% by mass. The obtained PFA aqueous dispersion 2 was stirred, coagulated, and dried to obtain PFA powder. The PPVE content of the obtained PFA powder was 6.5% by mass, the MFR was 2.1 g / 10 min, and the melting point was 295 °C.

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

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

[0487] Production Example 4 A PVdF aqueous dispersion was obtained with reference to Example 1 of JP-A-2014-141673. That is, 1700 g of pure water, 0.85 g of H-(CF2CF2)3-CH2-O-CO-CH2CH(-SO3Na)-CO-O-CH2-(CF2CF2)3-H (surface tension 22 mN / m) as a fluorine-containing surfactant, and 17 g of paraffin wax were placed in a 3.0 L SUS reactor, and the reactor was purged with nitrogen to remove oxygen. Then, 150 g of vinylidene fluoride (VdF) was added, and the temperature inside the reactor was raised to 115°C. While stirring the contents, 0.5 g of acetone and 5.6 g of di-t-butyl peroxide were added to initiate the reaction. Vinylidene fluoride was added dropwise over 9 hours in an amount of 427 g so that the pressure inside the tank was maintained at 4.0 MPaG. During the reaction, 1.45 g of H-(CF2CF2)3-CH2-O-CO-CH2CH(-SO3Na)-CO-O-CH2-(CF2CF2)3-H was added to obtain a PVdF aqueous dispersion. The solid content concentration of the obtained PVdF aqueous dispersion was 20.6 mass %. The obtained PVdF aqueous dispersion was coagulated, dried at 120°C, and pulverized to obtain a PVdF powder. The melting point of PVdF was 161°C, the average particle diameter was 1.1 μm, and the amount of fluorine-containing surfactant was 110 mass ppb.

[0488] Production 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 composition ratio in the obtained VT aqueous dispersion was VdF / TFE = 67.0 / 33.0 (mol%), the weight average molecular weight was 1,300,000, and the melting point was 160°C. Also, the obtained VT aqueous dispersion was stirred, coagulated, and dried at 120°C to obtain a powder. The obtained powder was pulverized with a high-speed mill to obtain VT powder. The average particle diameter of the obtained VT powder was 1.1 μm, and the fluorine-containing surfactant content was 340 mass ppb.

[0490] Production Example 7 1650 ml of pure water was put into a 3 L SUS autoclave, purged with nitrogen, slightly pressurized with hexafluoropropylene (HFP), temperature-controlled to 80°C while stirring, and HFP was pressured in up to 0.23 MPaG. Further, a mixed liquid monomer with a molar ratio of vinylidene fluoride (VdF) to HFP of 78.2 / 21.8 was pressured in up to 1.472 MPaG. 0.097 ml of 2-methylbutane was pressured in with nitrogen, and a solution of 36.4 g of ammonium persulfate dissolved in 80 ml of pure water was pressured in with nitrogen to start the reaction. When the pressure dropped to 1.44 MPaG, the pressure was raised to 1.50 MPaG with continuous monomer and maintained. After about 9.3 hours from the start of the reaction, when 607 g of continuous monomer was charged, stirring was stopped, the gas in the autoclave was released, and cooled to recover 2299 g of a dispersion. The solid content concentration of the obtained elastomer aqueous dispersion was 26.9 mass%. The composition of the obtained elastomer was VdF / HFP = 77.9 / 22.1 (mol%). The Mooney viscosity (ML1+10(140°C)) of the obtained elastomer was 77, the weight average molecular weight was 850,000, and the Tg was -18°C by DSC. Also, the heat of fusion was not observed in the second run.

[0491] Production Example 8 A 6-liter SUS reactor equipped with a SUS stirring blade and a temperature control jacket was charged with 3480 g of deionized water, 100 g of paraffin wax, and 5.3 g of white solid A. While heating to 70 °C, the inside of the reactor was purged with nitrogen gas to remove oxygen. TFE was injected to set the system pressure to 0.78 MPaG, and the system temperature was maintained at 70 °C while stirring. Next, an aqueous solution prepared by dissolving 15.0 mg of ammonium persulfate in 20 g of water was injected with TFE to initiate the polymerization reaction. As the polymerization reaction proceeded, 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 since the start of polymerization, an aqueous solution prepared by dissolving 18.0 mg of hydroquinone in 20 g of water as a radical scavenger was injected with TFE. Polymerization continued thereafter. When the polymerization amount of TFE reached approximately 1200 g since the start of polymerization, stirring and the supply of TFE were stopped, and immediately the gas inside the system was released to normal pressure to terminate the polymerization reaction. The aqueous dispersion was taken out, cooled, and the paraffin wax was separated to obtain an aqueous PTFE dispersion. The average primary particle diameter of the obtained aqueous PTFE dispersion was 310 nm, and the solid content concentration was 25.3 mass%. The obtained aqueous PTFE dispersion was coagulated and dried to obtain a PTFE powder. The SSG of the obtained PTFE powder was 2.156, and the endothermic peak temperature was 343 °C.

[0492] Preparation Example 2 A mixture of 10-undecen-1-ol (16 g), 1,4-benzoquinone (10.2 g), DMF (160 mL), water (16 mL), and PdCl2 (0.34 g) was heated and stirred at 90 °C for 12 hours. Thereafter, the solvent was distilled off under reduced pressure. The obtained residue was purified by liquid separation and column chromatography to obtain 11-hydroxyundecan-2-one (15.4 g). A mixture of 11-hydroxyundecan-2-one (13 g), sulfur trioxide triethylamine complex (13.9 g), and tetrahydrofuran (140 mL) was stirred at 50 °C for 12 hours. A sodium methoxide (3.8 g) / methanol (12 mL) solution was added dropwise to the reaction solution. The precipitated solid was filtered under reduced pressure, washed with ethyl acetate, and 15.5 g of sodium 10-oxoundecyl sulfate (hereinafter referred to as surfactant A) was obtained. To a glass reactor with a stirrer having an internal volume of 1 L, 588.6 g of deionized water and 70.0 g of surfactant A were added. The reactor was sealed, and the inside of 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 charged and stirred for 3 hours. Stirring was stopped, and the reactor was depressurized until it reached atmospheric pressure and then cooled to obtain an aqueous surfactant solution B.

[0493] Production Example 9 To a SUS reactor with a stirrer having an internal volume of 6 L, 3600 g of deionized and degassed water, 180 g of paraffin wax, and 0.540 g of surfactant A were added. The reactor was sealed, and the inside of the system was purged with nitrogen to remove oxygen. The reactor was heated to 70 °C, filled with TFE, and the reactor was brought to 2.70 MPa. 0.620 g of ammonium persulfate (APS) and 1.488 g of dicumyl peroxide (DSP) were charged as polymerization initiators. TFE was charged so that the reaction pressure remained constant at 2.70 MPa. Simultaneously with the start of charging TFE, the aqueous surfactant solution B was continuously charged. When 540 g of TFE was charged, 20 g of deionized and degassed water in which 0.76 g of hydroquinone was dissolved was added. When 1200 g of TFE was charged, stirring was stopped, and the reactor was depressurized until it reached atmospheric pressure. A total of 103 g of the aqueous surfactant solution B was charged by the end of the reaction. The content was taken out of the reactor, cooled, and the paraffin wax was separated to obtain an aqueous dispersion B of a TFE-based polymer. The solid content of the obtained aqueous dispersion B of the TFE-based polymer was 25.9% by mass, and the average primary particle diameter was 290 nm.

[0494] The obtained aqueous dispersion B of the TFE-based polymer was diluted with deionized water to a solid content concentration of 13% by mass, vigorously stirred in a container equipped with a stirrer to cause coagulation, and then separated from water by filtration to obtain a wet powder. The obtained wet powder was placed on a stainless steel mesh tray, and the mesh tray was heat-treated in a hot air circulation electric furnace at 210 °C. After 18 hours, the mesh tray was taken out and air-cooled to obtain PTFE powder. The obtained 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 reduction temperature of 397 °C, and a 1.0% by mass reduction temperature of 492 °C. Compounds represented by the general formula (1) with carbon numbers m = 15 and 16 were detected in the obtained PTFE powder. The content of the compound represented by the general formula (1) with carbon number m = 15 was 73 mass ppb, and the content of the compound represented by the general formula (1) with carbon number m = 16 was 141 mass ppb. In addition, compounds represented by the general formula (2) with carbon numbers n = 4, 6, 8, 10, 12, and 14 were detected, and the content of the compound represented by the general formula (2) with carbon number n = 8 was 1413 mass ppb.

[0495] Production Example 1 886 g of the PTFE aqueous dispersion obtained in Production Example 1 and 197 g of the PFA aqueous dispersion 2 obtained in Production Example 2 were placed in a container, diluted with deionized water to a solid content concentration of 13% by mass, and the PTFE / PFA mixture was co-precipitated while stirring at high speed. Then, it was separated from water by filtration to obtain a wet powder. The obtained wet powder was placed on a stainless steel mesh tray, and the mesh tray was heat-treated in a hot air circulation electric furnace at 240 °C. After 20 hours, the mesh tray was taken out and air-cooled to obtain a PTFE / PFA mixed powder. The mixing ratio (mass ratio) of the obtained PTFE / PFA mixed powder was PTFE / PFA = 80 / 20. The obtained PTFE / PFA mixed powder was designated as Polymer Composition A. The endothermic peak temperatures of Polymer Composition A were 295 °C and 342 °C, the thermal instability index was 56, the 0.1% by mass reduction temperature was 385 °C, the 1.0% by mass reduction temperature was 486 °C, and the moisture content was 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 t...

Claims

1. A polymer composition used as a binder for an electrochemical device, the polymer composition comprising a fibrillatable polymer, a thermoplastic polymer, and at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2). General formula (1): (H-(CF ２ )) ｍ－１ -COO) ｐ M １ (wherein m is from 4 to 20. M １ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ )) ｎ -SO ３ )) ｑ M ２ (In the formula, n is 4 to 20. M ２ is H, a metal atom, NR ５ ４ (R ５ is the same as described above), 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.)

2. A polymer composition used as a binder for an electrochemical device, the polymer composition comprising a fibrillatable polymer and a thermoplastic polymer, wherein the thermal instability index (TII) of the fibrillatable polymer is 10 or more.

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

4. The polymer composition according to claim 1 or 2, wherein the content of the fibrillatable polymer is more than 50% by mass and 97% by mass or less with respect to the polymer composition.

5. The polymer composition according to claim 1 or 2, wherein the thermoplastic polymer is at least one vinylidene fluoride-based polymer selected from the group consisting of polyvinylidene fluoride and a vinylidene fluoride / tetrafluoroethylene copolymer.

6. The polymer composition according to claim 1 or 2, which is a powder.

7. The polymer composition according to claim 1 or 2, which is used as a binder for a lithium ion secondary battery.

8. A binder for an electrochemical device consisting essentially of only a polymer composition, wherein the polymer composition comprises a fibrillatable polymer, a thermoplastic polymer, and at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2). General formula (1): (H-(CF ２ )) ｍ－１ -COO) ｐ M １ (wherein m is 4 to 20. M １ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (2): (H-(CF ２ )) ｎ -SO ３ )) ｑ M ２ (wherein n is 4 to 20. M ２ is H, a metal atom, NR ５ ４ (R ５ is the same as above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. q is 1 or 2.)

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

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

11. The binder for an electrochemical device according to claim 8 or 9, wherein the endothermic peak temperature of the fibrillatable polymer is above 330 °C.

12. The binder for an electrochemical device according to claim 8 or 9, wherein the fibrillatable polymer is a tetrafluoroethylene-based polymer.

13. The binder for an electrochemical device according to claim 8 or 9, wherein the fibrillatable polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene consisting only of a polymerization unit based on a tetrafluoroethylene unit and a hexafluoropropylene unit.

14. The binder for an electrochemical device according to claim 8 or 9, wherein the thermal instability index (TII) of the fibrillatable polymer is 10 or more.

15. The binder for an electrochemical device according to claim 8 or 9, wherein the amount of the thermoplastic polymer in the polymer composition is less than 50% by mass.

16. The binder for an electrochemical device according to claim 8 or 9, wherein the content of the fibrillatable polymer is more than 50% by mass and 97% by mass or less with respect to the polymer composition.

17. The binder for an electrochemical device according to claim 8 or 9, wherein the 0.1% mass loss temperature of the polymer composition is 340 °C or higher.

18. The binder for an electrochemical device according to claim 8 or 9, wherein the 1.0% mass loss temperature of the polymer composition is 370 °C or higher.

19. The binder for an electrochemical device according to claim 8 or 9, wherein the thermoplastic polymer is a vinylidene fluoride-based polymer.

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

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

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

23. The polymer composition is a binder for an electrochemical device according to claim 8 or 9, having an endothermic peak in the range of at least 130 to 200 °C.

24. The binder for an electrochemical device according to claim 8 or 9, 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.

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

26. The binder for an electrochemical device according to claim 8 or 9, wherein the average aspect ratio of the polymer composition in powder form is 2.5 or less.

27. The binder for an electrochemical device according to claim 8 or 9, wherein the powder of the fibrillatable polymer is not fibrillated.

28. The binder for an electrochemical device according to claim 8 or 9, which is in powder form.

29. The binder for an electrochemical device according to claim 8 or 9, which is a binder for a lithium-ion secondary battery.

30. An electrode mixture containing the polymer composition according to claim 1 or 2, or the binder for an electrochemical device according to claim 8 or 9, and an electrode active material.

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

32. An electrode containing the polymer composition according to claim 1 or 2, or the binder for an electrochemical device according to claim 8 or 9, an electrode active material, and a current collector.

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

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