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

Abstract

To provide a tetrafluoroethylene (TFE)-based polymer composition for a binder for an electrochemical device, which is capable of reducing the resistance of a mixture sheet.SOLUTION: A TFE-based polymer composition is used for a binder for an electrochemical device and includes a TFE-based polymer, at least one kind of compound selected from the group consisting of compounds represented by General Formulae (1) and (2), and a conductive carbon material, in which the amount of TFE-based polymer relative to the solid content is 10 mass% or more. General Formula (1): (H-(CF2)m-1-COO)pM1 (in which m represents 4 to 20, M1 represents H, a metal atom, or 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 tetrafluoroethylene-based polymer composition, a binder for an electrochemical device, an electrode binder, an electrode, and a secondary battery.

Background Art

[0002] Secondary batteries such as lithium-ion secondary batteries are used in small and portable electrical and electronic devices such as notebook computers, mobile phones, smartphones, tablet computers, and ultrabooks because of their high voltage, high energy density, low self-discharge, low memory effect, and ability to achieve ultra-lightweight. Furthermore, they are being put into practical use as a wide range of power sources, from in-vehicle drive power sources for automobiles to stationary large-scale power sources. There is a demand for further increasing the energy density of secondary batteries and further improving battery characteristics.

[0003] Patent Documents 1 to 4 describe a binder obtained by mixing polytetrafluoroethylene and a conductive carbon material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure aims to provide a tetrafluoroethylene-based polymer composition for a binder for an electrochemical device that can reduce the resistance of a pharmaceutical sheet, as well as a binder for an electrochemical device, an electrode mixture, an electrode, and a secondary battery using the same.

Means for Solving the Problems

[0006] The present disclosure (1) is a tetrafluoroethylene-based polymer composition used for a binder for an electrochemical device, comprising a tetrafluoroethylene-based polymer, at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and a conductive carbon material, wherein the amount of the tetrafluoroethylene-based polymer with respect to the solid content in the tetrafluoroethylene-based polymer composition is 10% by mass or more. 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), 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.)

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

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

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

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

[0011] The present disclosure (6) is a binder for an electrochemical device consisting essentially of only a tetrafluoroethylene-based polymer composition, wherein the tetrafluoroethylene-based polymer composition contains a tetrafluoroethylene-based polymer, at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and a conductive carbon material, and the amount of the tetrafluoroethylene-based polymer with respect to the solid content in the tetrafluoroethylene-based polymer composition is 10% by mass or more. 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.)

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

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

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

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

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

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

[0018] The present disclosure (13) is a binder for an electrochemical device according to any one of the present disclosures (6) to (12), wherein the tetrafluoroethylene-based polymer composition substantially does not contain moisture.

[0019] The present disclosure (14) is a binder for an electrochemical device according to any one of the present disclosures (6) to (13), wherein the tetrafluoroethylene-based polymer composition substantially does not contain a compound represented by the following general formula (3). General formula (3): (H-(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), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. q is 1 or 2.)

[0020] The present disclosure (15) is a binder for an electrochemical device according to any one of the present disclosures (6) to (14), wherein the tetrafluoroethylene-based polymer composition contains at least one compound selected from the group consisting of a compound represented by the following general formula (4) and a compound represented by the following general formula (4’), and the content of each of them is 1000 mass ppb or less with respect to the tetrafluoroethylene-based polymer composition. General formula (4): (H-(CF2) 15 -COO) p M 1 (In the formula, M 1 is H, a metal atom, NR 5 4 (R 5 may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (4’): (H-(CF2) 16 -COO) p M 1 (In the formula, M 1 is H, a metal atom, NR 5 4 (R 5 is the same as above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.)

[0021] The present disclosure (16) is a binder for an electrochemical device according to any one of the present disclosures (6) to (15), wherein the tetrafluoroethylene-based polymer composition contains at least one compound selected from the group consisting of a compound represented by the following general formula (5) and a compound represented by the following general formula (5’), and the content of each of them is 1000 mass ppb or less with respect to the tetrafluoroethylene-based polymer composition. 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), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (5’): (H-(CF2) 14 -COO) p M 1 (In the formula, M 1 is H, a metal atom, NR5 4(R 5 which 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. p is 1 or 2.)

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

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

[0024] The present disclosure (19) is a binder for an electrochemical device according to any one of the present disclosures (6) to (18), which is for a lithium-ion secondary battery.

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

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

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

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

Advantages of the Invention

[0029] According to the present disclosure, a tetrafluoroethylene-based polymer composition for a binder for an electrochemical device capable of reducing the resistance of a composite sheet, and a binder for an electrochemical device, an electrode composite, an electrode, and a secondary battery using the same can be provided.

Mode for Carrying Out the Invention

[0030] 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.

[0031] Hereinafter, the present disclosure will be specifically described.

[0032] The present disclosure is a tetrafluoroethylene (TFE)-based polymer composition used for a binder for an electrochemical device, which includes a TFE-based polymer, at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and a conductive carbon material, and provides a TFE-based polymer composition in which the amount of the TFE-based polymer relative to the solid content in the TFE-based polymer composition is 10% by mass or more. 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 (R5 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.)

[0033] By having the above configuration, the TFE-based polymer composition of the present disclosure can reduce the resistance of the pharmaceutical sheet. Further, when in the form of a powder, the fluidity can also be improved. Since the TFE-based polymer composition 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 selection of electrode active materials and solid electrolytes to be combined is possible, which is advantageous in the production process. Further, the steps and costs due to the use of the dispersion medium can be reduced. Furthermore, since the TFE-based polymer composition of the present disclosure is excellent in the adhesion force to the active material and the electrolyte, the amount used can be reduced.

[0034] The TFE-based polymer in the TFE-based polymer composition of the present disclosure 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% by mass or more of TFE units and 1.0% by mass or less of modified monomer units. The above TFE-based polymer is preferably PTFE and more preferably modified PTFE in terms of obtaining a pharmaceutical sheet with even lower resistance and further improving the powder fluidity. In the present disclosure, the homopolymer of TFE refers to one in which the content of the modified monomer unit with respect to all polymerization units is less than 0.0001% by mass.

[0035] The content of the modified monomer unit is preferably in the range of 0.0001 to 10% by mass with respect to all polymerization units in terms of obtaining a composite sheet with lower resistance and further improving powder fluidity. As the lower limit of the content of the modified monomer unit, 0.001% by mass is more preferable, 0.010% by mass is still more preferable, 0.015% by mass is even more preferable, and 0.020% by mass is particularly preferable. As the upper limit of the content of the modified monomer unit, 5.0% by mass is preferable, 3.0% by mass is more preferable, 1.0% by mass is still more preferable, 0.80% by mass is even more preferable, 0.60% by mass is even more preferable, 0.50% by mass is even more preferable, 0.40% by mass is even more preferable, 0.30% by mass is even more preferable, and 0.20% by mass is particularly preferable. In this specification, the above-mentioned modified monomer unit means a part of the molecular structure of the TFE-based polymer that is derived from the modified monomer.

[0036] The content of each of the above-mentioned polymerization units can be calculated by appropriately combining NMR, FT-IR, elemental analysis, and fluorescent X-ray analysis according to the type of monomer.

[0037] The above-mentioned modified monomer is not particularly limited as long as it can copolymerize with TFE. For example, perfluoroolefins such as hexafluoropropylene [HFP]; hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride [VDF]; perhaloolefins such as chlorotrifluoroethylene [CTFE]; perfluorovinyl ether; perfluoroallyl ether; (perfluoroalkyl)ethylene, ethylene, monomers having a polar group, etc. can be mentioned. Also, the modified monomer used may be one type or a plurality of types.

[0038] The above-mentioned perfluorovinyl ether is not particularly limited. For example, the following general formula (A): CF2=CF-ORf 1 (A) (In the formula, Rf 1represents 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.

[0039] 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.

[0040] 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.

[0041] Furthermore, examples of the above-mentioned perfluorovinyl ether include those in which, in the above general formula (A), Rf 1 is a perfluoro(alkoxyalkyl) group having 4 to 9 carbon atoms, and those in which Rf 1 is a group represented by the following formula:

[0042]

Chemical formula

[0043] (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:

[0044]

Chemical formula

[0045] (wherein n represents an integer of 1 to 4), and the like.

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

[0047] 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.

[0048] The above Rf 2 is preferably a perfluoroalkyl group having 1 to 10 carbon atoms or a perfluoroalkoxyalkyl group having 1 to 10 carbon atoms. 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 still more preferable.

[0049] 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 preferable.

[0050] 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.

[0051] The monomer having the polar group may be a non-fluorine monomer or a fluorine-containing monomer.

[0052] 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 vinyl sulfonic 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.

[0053] The monomer having the above polar group preferably includes a modified monomer having a functional group capable of reacting by radical polymerization and a hydrophilic group (hereinafter referred to as "modified monomer (A)").

[0054] Examples of the hydrophilic group in the above modified monomer (A) include -NH2, -PO3M, -OPO3M, -SO3M, -OSO3M, -COOM (in each formula, M is H, a metal atom, NR 7 4, imidazolium which may have a substituent, pyridinium which may have a substituent or phosphonium which may have a substituent, R 7 is H or an organic group, and may be the same or different. Any two of them may be bonded to each other to form a ring.). Among the above hydrophilic groups, -SO3M or -COOM is preferable. R 7 is preferably H or an organic group of C 1-10 and more preferably H or an organic group of C 1-4 and still more preferably H or an alkyl group of C 1-4 . Examples of the above metal atom include monovalent and divalent metal atoms, such as alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K or Li is preferable.

[0055] Examples of the "functional group capable of reacting by radical polymerization" in the above modified 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 has the following formula: CX e X g =CX f R- (wherein X e , X f and X g are each independently F, Cl, H, CF3, CF2H, CFH2, or CH3; and R is a linking group.). Examples of the linking group of R include the linking group as R a described later. Preferably -CH=CH2, -CF=CH 2、 -CH=CF 2、Groups having an unsaturated bond such as -CF=CF2, -CH2-CH=CH2, -CF2-CF=CH2, -CF2-CF=CF2, -(C=O)-CH=CH2, -(C=O)-CF=CH2, -(C=O)-CH=CF2, -(C=O)-CF=CF2, -(C=O)-C(CH3)=CH2, -(C=O)-C(CF3)=CH2, -(C=O)-C(CH3)=CF2, -(C=O)-C(CF3)=CF2, -O-CH2-CH=CH2, -O-CF2-CF=CH2, -O-CH2-CH=CF2, -O-CF2-CF=CF2, etc. are exemplified.

[0056] 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.

[0057] The above-mentioned modified monomer (A) may be used alone or in combination of two or more.

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

[0059] 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) (wherein, X 1 represents F or CF3, n3 represents an integer of 1 to 10, and Y 3 is the same as defined 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 are the same as defined above.) CX 2 2=CFCF2-O-(CF(CF3)CF2O) n5 -CF(CF3)-Y 3 (4e) (wherein each X 2 is the same, and represents F or H. n5 represents 0 or an integer of 1 to 10, and Y 3 is the same as defined above.) Examples of the alkali metal include Na, K, etc.

[0060] In the above formula (4a), it is preferable that the above n1 is an integer of 5 or less, and more preferably an integer of 2 or less. The above Y 3 is preferably -COOM 1 in terms of obtaining appropriate water solubility and surface activity, and M 1 is preferably H or NH4 in terms of being difficult to remain as an impurity and improving the heat resistance of the resulting molded article.

[0061] Examples of the perfluorovinyl alkyl compound represented by the above formula (4a) include, for example, CF2=CFCF2COOM 1 (wherein, M 1 is the same as defined above.)

[0062] In the above formula (4b), in terms of emulsifying ability, it is preferable that the above n2 is an integer of 3 or less, and Y 3is preferably -COOM in terms of obtaining appropriate water solubility and surface activity. 1 is preferably M 1 is preferably H or NH4 in that it is difficult to remain as an impurity and the heat resistance of the resulting molded article is improved.

[0063] In the above formula (4c), n3 is preferably an integer of 5 or less in terms of water solubility, and Y 3 is preferably -COOM in terms of obtaining appropriate water solubility and surface activity. 1 is preferably M 1 is preferably H or NH4 in terms of improving dispersion stability.

[0064] In the above formula (4d), X 1 is preferably -CF3 in terms of surface activity performance, n4 is preferably an integer of 5 or less in terms of water solubility, and Y 3 is preferably -COOM in terms of obtaining appropriate water solubility and surface activity. 1 is preferably M 1 is preferably H or NH4.

[0065] Examples of the perfluorovinyl ether compound represented by the above formula (4d) include CF2=CFOCF2CF(CF3)OCF2CF2COOM 1 (wherein M 1 represents H, NH4 or an alkali metal).

[0066] In the above formula (4e), n5 is preferably 0 or an integer of 1 to 5 in terms of emulsifying ability, more preferably 0, 1 or 2, and still more preferably 0 or 1. Y 3 is preferably -COOM in terms of obtaining appropriate water solubility and surface activity. 1 is preferably M 1 is preferably H or NH4 in that it is difficult to remain as an impurity and the heat resistance of the obtained molded article is improved.

[0067] Examples of the perfluorovinyl alkyl compound represented by the above formula (4e) include CH2=CFCF2OCF(CF3)COOM 1 and CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOM 1 (wherein M 1 is the same as defined above).

[0068] As the above-mentioned modified monomer, at least one selected from the group consisting of HFP, CTFE, PAVE, PFAE, and a monomer having a polar group is preferable in terms of obtaining a composite sheet with lower resistance and further improving the powder fluidity. More preferably, at least one selected from the group consisting of HFP, CTFE, 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 selected. Even more preferably, at least one selected from the group consisting of HFP, CTFE, PMVE, PPVE, a cyclic non-fluorine monomer having an acid anhydride residue, and a compound represented by the general formula (4e) is selected. Even more preferably, at least one selected from the group consisting of HFP, CTFE, and PPVE is selected. Even more preferably, HFP is selected.

[0069] 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. More preferably, it is 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.

[0070] The above TFE-based polymer may have a core-shell structure. Examples of the TFE-based polymer having a core-shell structure include, for example, 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 the 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, for example, the PTFE described in JP-T-2005-527652.

[0071] 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 and a load of 5 kg using a melt indexer in accordance with ASTM D1238.

[0072] The above TFE-based polymer may have a 0.1% mass loss temperature of 400 °C or lower. A TFE-based polymer having a 0.1% mass loss temperature of 400 °C or lower is obtained by using a hydrocarbon-based surfactant. The above 0.1% mass loss temperature is a value measured by the following method. Weigh accurately about 10 mg of a TFE-based polymer without a heating history at a temperature of 300 °C or higher, place it in a dedicated aluminum pan, and measure it with a TG·DTA (simultaneous differential thermal and thermogravimetric analyzer). The 0.1% mass loss temperature is the temperature corresponding to the point where the weight has decreased by 0.1 mass% when the temperature of the aluminum pan is raised from 25 °C to 600 °C at a rate of 10 °C / min in an air atmosphere.

[0073] The above TFE-based polymer may have a 1.0% mass loss temperature of 492 °C or lower. A TFE-based polymer with a 1.0% mass loss temperature of 492 °C or lower can be obtained by using a hydrocarbon surfactant. The above 1.0% mass loss temperature is the value measured by the following method. Precisely weigh approximately 10 mg of a TFE-based polymer without a heating history at a temperature of 300 °C or higher, place it in a dedicated aluminum pan, and measure it using a 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 aluminum pan is heated from 25 °C to 600 °C at a rate of 10 °C / min under an air atmosphere.

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

[0075] The content of the above TFE-based polymer is 10 mass% or more based on the solid content in the above TFE-based polymer composition. In terms of obtaining a composite sheet with even lower resistance and further improving the powder fluidity, it is preferably 20 mass% or more, more preferably 30 mass% or more, still more preferably 40 mass% or more, still more preferably 50 mass% or more, particularly preferably 55 mass% or more, and also preferably 99 mass% or less, more preferably 96 mass% or less, still more preferably 91 mass% or less, still more preferably 85 mass% or less, still more preferably 80 mass% or less, still more preferably 75 mass% or less, and particularly preferably 70 mass% or less. In the present disclosure, the amount of solids in the TFE-based polymer composition is a value obtained by drying 1 g of the TFE-based polymer composition in a forced-air dryer at 150°C for 60 minutes and expressing the ratio of the mass of the heat residue to the mass of the TFE-based polymer composition (1 g) as a percentage.

[0076] The TFE-based polymer composition of the present disclosure contains at least one compound selected from the group consisting of a compound represented by the following general formula (1) (hereinafter also referred to as compound (1)) and a compound represented by the following general formula (2) (hereinafter also referred to as compound (2)). General formula (1): (H-(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.)

[0077] As the above metal atoms for M 1 and M 2 include monovalent and divalent metal atoms, such as alkali metals (Group 1) or alkaline earth metals (Group 2), and specifically, Na, K, Li, etc. are exemplified. The four Rs 5 may be the same or different. R 5is preferably H or an organic group having 1 to 10 carbon atoms, more preferably H or an organic group having 1 to 4 carbon atoms. R 5 The organic group as is preferably a fluorine-free organic group.

[0078] In the 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 the 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.

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

[0080] When the TFE-based polymer composition of the present disclosure contains the compound (1), the content of the 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 150 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, and particularly preferably 10 mass ppb or less with respect to the above TFE-based polymer composition. The lower limit is not particularly limited, but may be 0.1 mass ppb, may be 1 mass ppb, may be 10 mass ppb, or may be 15 mass ppb.

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

[0082] When the TFE-based polymer composition of the present disclosure contains the compound (2), the content of the 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 1500 mass ppb or less, still 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.

[0083] The TFE-based polymer composition containing the compound (1) and / or (2) can be obtained by using a hydrocarbon-based surfactant. The TFE-based polymer composition of the present disclosure may contain a hydrocarbon-based surfactant together with the TFE-based polymer and the compound (1) and / or (2). The content of the hydrocarbon-based surfactant in the TFE-based polymer composition is not particularly limited, but is usually 100 mass ppm to 10 mass%. It is preferable that in the hydrocarbon-based 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).

[0084] The TFE-based 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 5may be the same or different, and is H, an organic group having 1 to 10 carbon atoms (preferably an organic group not containing fluorine), an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent. q is 1 or 2.)

[0085] Substantially free of compound (3) means that the content of compound (3) is 25 mass ppb or less based on the above TFE-based polymer composition. The content of compound (3) is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, and still more preferably 10 mass ppb or less based on the above TFE-based polymer composition. 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.

[0086] The TFE-based polymer composition of the present disclosure contains at least one compound selected from the group consisting of a compound represented by the following general formula (4) (hereinafter also referred to as compound (4)) and a compound represented by the following general formula (4') (hereinafter also referred to as compound (4')), and the content of each of them is preferably 1000 mass ppb or less based on the above TFE-based polymer composition. General formula (4): (H-(CF2) 15 -COO) p M 1 (In the formula, M 1 is H, a metal atom, NR 5 4 (R 5 may be the same or different, and is H, 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, a metal atom, NR 5 4 (R 5(the same as above), an optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium. p is 1 or 2.)

[0087] When the TFE-based 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 150 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 TFE-based polymer composition. The lower limit is not particularly limited and may be 0.1 mass ppb, may be 1 mass ppb, may be 20 mass ppb, or may be 50 mass ppb.

[0088] When the TFE-based 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 150 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 TFE-based polymer composition. The lower limit is not particularly limited and may be 0.1 mass ppb, may be 1 mass ppb, may be 20 mass ppb, or may be 50 mass ppb.

[0089] The TFE-based polymer composition of the present disclosure contains at least one compound selected from the group consisting of a compound represented by the following general formula (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 TFE-based 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.)

[0090] When the TFE-based 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 TFE-based polymer composition. The lower limit is not particularly limited, and may be 0.1 mass ppb, may be 1 mass ppb, or may be 10 mass ppb.

[0091] When the TFE-based polymer composition of the present disclosure contains the compound (5'), the content of the 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 TFE-based polymer composition. The lower limit is not particularly limited and may be 0.1 mass ppb, may be 1 mass ppb, or may be 10 mass ppb.

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

[0093] As the conductive carbon material in the TFE-based polymer composition of the present disclosure, known ones can be arbitrarily used. Specific examples include carbon materials such as 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, needle coke, carbon nanotubes, carbon nanohorns, carbon nanofibers, fullerenes and graphene, and amorphous carbon such as VGCF. In particular, acetylene black, VGCF, and carbon nanotubes are preferred. Among them, multi-walled carbon nanotubes are preferred as the carbon nanotubes. These may be used alone, or two or more of them may be used in combination at an arbitrary combination and ratio.

[0094] Examples of commercially available carbon blacks include, for example, Tokablack #4300, #4400, #4500, #5500, etc. (manufactured by Tokai Carbon Co., Ltd., furnace black), Printex L, etc. (manufactured by Degussa AG, furnace black), Raven7000, 5750, 5250, 5000ULTRAIII, 5000ULTRA, etc., Conductex SC ULTRA, Conductex 975ULTRA, etc., PUER BLACK100, 115, 205, etc. (manufactured by Columbian Chemicals Company, furnace black), #2350, #2400B, #2600B, #30050B, #3030B, #3230B, #3350B, #3400B, #5400B, etc. (manufactured by Mitsubishi Chemical Corporation, furnace black), MONARCH1400, 1300, 900, VulcanXC-72R, BlackPearls2000, LITX-50, LITX-200, etc. (manufactured by Cabot Corporation, furnace black), Ensaco250G, Ensaco260G, Ensaco350G, Super-P Li (manufactured by Imerys, furnace black), Ketjenblack ECP, ECP-600JD, Lionite CB, etc. (manufactured by Lion Specialty Chemicals Co., Ltd., Ketjenblack), Denka Black HS-100, Li-100, Li-200, Li-250, Li-400, FX-35 (manufactured by Denka Co., Ltd., acetylene black), and the like. The purity of the carbon black preferably has a fixed carbon content of 99.00% by mass or more, more preferably 99.50% by mass or more. The ash content is preferably 0.50% by mass or less, more preferably 0.30% by mass or less. Examples of commercially available VGCF include VGCF-H (manufactured by Showa Denko K.K.). Examples of commercially available multi-walled carbon nanotubes include FT7000 (manufactured by CNano). As the multi-walled carbon nanotube, the average outer diameter is preferably 4 nm to 20 nm, more preferably 6 nm to 12 nm. The average fiber length is preferably 1 to 30 μm, more preferably 3 μm to 20 μm. The specific surface area is preferably 10 to 800 m 2 / g, more preferably 100 to 400 m 2 / g. Thereby, good conductivity can be obtained.

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

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

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

[0098] The TFE-based polymer composition of the present disclosure may not contain an electrode active material and a solid electrolyte.

[0099] The TFE-based polymer composition of the present disclosure preferably contains substantially no moisture. Thereby, gas generation and deterioration of the characteristics of the electrochemical device can be suppressed. Further, since the electrode active material and the solid electrolyte to be combined can be widely selected, it is advantageous in the production process. Substantially containing no moisture means that the moisture content with respect to the above TFE-based polymer composition is 0.050% by 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, still more preferably 0.003% by mass or less, still 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 TFE-based 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, find the average, and adopt the average value. Moisture content (% by mass) = [(mass of TFE-based polymer composition before heating (g)) - (mass of TFE-based polymer composition after heating (g))] / (mass of TFE-based polymer composition before heating (g)) × 100

[0100] The TFE-based polymer composition of the present disclosure preferably contains substantially no fluorine-containing compound having a molecular weight of 1000 or less. Substantially containing no fluorine-containing compound means that the amount of the fluorine-containing compound is 25 mass ppb or less with respect to the above TFE-based polymer composition. The amount of the fluorine-containing compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, still more preferably 10 mass ppb or less, still more preferably less than 10 mass ppb, 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.

[0101] The amount of the 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 of each content, plot the relationship between the content and the area of the area corresponding to the content, and draw a calibration curve. Using the above calibration curve, convert the area of 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.

[0102] Examples of the fluorine-containing compound having a molecular weight of 1000 or less include fluorine-containing compounds having a hydrophilic group with a molecular weight of 1000 g / mol or less. The molecular weight of the above fluorine-containing compound is preferably 800 or less, and more preferably 500 or less. In addition to the TFE-based polymer, the polymer particles obtained by polymerization carried out in the presence of a fluorine-containing surfactant usually contain the fluorine-containing surfactant. In this specification, the fluorine-containing surfactant is the one used during polymerization. The fluorine-containing compound having a molecular weight of 1000 or less may be a compound that is not added during polymerization, for example, a compound that is by-produced during the polymerization process. Note that when the fluorine-containing compound having 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 TFE-based polymer is not included in the fluorine-containing compound having a molecular weight of 1000 or less.

[0103] 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 imidazolium which may have a substituent, pyridinium which may have a substituent or phosphonium which may have a substituent, and R 1 is H or an organic group. Examples thereof include anionic groups such as

[0104] As the fluorine-containing surfactant, a surfactant containing fluorine with a molecular weight of the anionic moiety of 1000 or less (anionic fluorine-containing surfactant) can also be used. The above-mentioned "anionic moiety" means the part excluding the cation of the 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-mentioned 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, which is linear, branched or cyclic, and in which some or all of the H are substituted by F, and the alkylene group may contain one or more ether bonds and some of the H may be substituted by Cl. Y 0 is an anionic group.) Compounds represented by 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 imidazolium which may have a substituent, pyridinium which may have a substituent or phosphonium which may have a substituent, and R 1 is H or an organic group. Examples of the above-mentioned metal atom 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, and 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. The above Rf n0 may have 50% or more of H substituted with fluorine.

[0105] The above fluorine-containing surfactant may be a single fluorine-containing surfactant or a mixture containing two or more fluorine-containing surfactants.

[0106] Examples of the above 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 TFE-based polymer composition of the present disclosure preferably does not substantially contain any of the fluorine-containing compounds represented by the above formula.

[0107] In each of the above formulas, 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 is H or an organic group of C 1-10 and may be H or an organic group of C 1-4 and may be H or an organic group of C 1-4 and may be an alkyl group of C.

[0108] When the TFE-based polymer composition of the present disclosure does not substantially contain any of the fluorine-containing compounds represented by the above formula, 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 formula means that the amount of the fluorine-containing compound is 25 mass ppb or less with respect to the above TFE-based 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, still more preferably less than 10 mass ppb, 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.

[0109] The TFE-based 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 M described above. 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 TFE-based polymer composition. The amount of the fluorine-containing compound is preferably 20 mass ppb or less, more preferably 15 mass ppb or less, still more preferably 10 mass ppb or less, still more preferably less than 10 mass ppb, still more preferably 1 mass ppb or less, still 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.

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

[0111] The TFE-based polymer composition of the present disclosure preferably has an endothermic peak temperature of 333 °C or higher, more preferably 335 °C or higher, still more preferably 337 °C or higher, still more 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 more excellent strength. The endothermic peak temperature is 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 on a TFE-based polymer composition that has no history of being heated to a temperature of 300°C or higher. When there are two or more minimum points in one melting peak, each is taken as the endothermic peak temperature.

[0112] The TFE-based polymer composition of the present disclosure preferably has a melting point of 315°C or higher, more preferably 320°C or higher, still more preferably 323°C or higher, even more preferably 325°C or higher, and also preferably 335°C or lower, more preferably 330°C or lower, in that it can form a sizing sheet with even better strength. The above melting point is 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 on a TFE-based polymer composition that has a history of being heated to a temperature of 300°C or higher.

[0113] The TFE-based polymer composition of the present disclosure 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, particularly preferably 2.180 or less, and especially preferably 2.170 or less, in that it can form a sizing sheet with even better strength. The above SSG is preferably 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.

[0114] The TFE-based 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, even 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, even more preferably 700 μm or less. The average secondary particle diameter is measured in accordance with JIS K 6891.

[0115] In terms of excellent handleability, the TFE-based polymer composition of the present disclosure may have an average aspect ratio of 2.0 or less, preferably 1.8 or less, more preferably 1.7 or less, still more preferably 1.6 or less, even more preferably 1.5 or less, even more preferably 1.4 or less, particularly preferably 1.3 or less, and most preferably 1.1 or less. The average aspect ratio may also be 1.0 or more. The average aspect ratio is determined from the average of the ratios of the major axis to the minor axis by observing the TFE-based polymer composition with a scanning electron microscope (SEM) and performing image processing on 200 or more randomly extracted particles.

[0116] In terms of excellent handleability, the TFE-based 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, even more preferably 0.48 g / ml or more, and particularly preferably 0.50 g / ml or more. The upper limit is not particularly limited, and it may be 0.70 g / ml. The apparent density is measured in accordance with JIS K 6892.

[0117] The form of the TFE-based polymer composition of the present disclosure is not limited, but it is preferably in powder form in that it can be mixed with an electrode active material or a solid electrolyte without using a large amount of a dispersion medium. In addition, the TFE-based polymer composition may be in a form other than powder, for example, a dispersion or a molded body. Examples of the molded body include a sheet, a pellet, a rod shape, and the like.

[0118] The TFE-based polymer composition of the present disclosure can be produced by mixing a TFE-based polymer and a conductive carbon material. By mixing the TFE-based polymer and the conductive carbon material before mixing with the electrode active material or the solid electrolyte, the dispersibility of the TFE-based polymer is improved. As a result, when preparing a mixture by mixing with an electrode active material or a solid electrolyte, the TFE-based polymer and the conductive carbon material are uniformly dispersed, so that resistance and other electrochemical device characteristics can be improved. Although the details of the principle are not clear, it is considered that by creating a state in which the TFE-based polymer and the conductive carbon material are mixed in advance, fibrils are generated while the soft TFE-based polymer is dispersed when mixed with the electrode active material or the solid electrolyte, and at the same time, the conductive carbon material can be efficiently dispersed. When the TFE-based polymer and the conductive carbon material are added separately without being mixed in advance, the polymer is preferentially dispersed and the dispersion of the conductive carbon material becomes insufficient.

[0119] The production method of the TFE-based polymer composition of the present disclosure is not particularly limited and can be produced by any method. Among them, it can be preferably produced by a production method having a step (A) of mixing a TFE-based polymer and a conductive carbon material in the presence of a liquid medium. In this case, examples include a method of adding and mixing a powdery conductive carbon material into a liquid dispersion of the TFE-based polymer, and a method of mixing a liquid dispersion of the TFE-based polymer and a liquid dispersion of the conductive carbon material. Mixing can be performed by a general method. For example, mixers such as a disper, a homomixer, a planetary mixer, homogenizers, a wet jet mill, etc. can be used, but it is not limited thereto.

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

[0121] Mixing these in a liquid medium is preferable in that the TFE-based polymer and the conductive carbon material can be mixed with high uniformity. The liquid medium in such mixing is preferably water.

[0122] In this case, as the TFE-based polymer used as a raw material, it is preferable to use an aqueous dispersion obtained by emulsion polymerization.

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

[0124] For the hydrocarbon-based surfactant, it is preferable that the ratio of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms is 50% or less, more preferably 25% or less, even more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0125] The above 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.

[0126] It is also preferable that the hydrocarbon surfactant is 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 among 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.

[0127] The 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 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.

[0128] The 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.

[0129] 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, stirred for a certain period of time, and then the reactor is depressurized until it reaches atmospheric pressure and 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.

[0130] 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 is started 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 is started. It is more preferable that the addition of the specific hydrocarbon surfactant is started 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 preferably when it is 0.1% by mass or less, and particularly preferably starting 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.

[0131] 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.

[0132] 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, there is a risk of a decrease in the polymerization rate or a reaction 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.

[0133] As the above-mentioned specific hydrocarbon surfactant, there is 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 represented by the formula and 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 above-mentioned specific hydrocarbon surfactant, there is the following formula (a):

Chemical formula

Chemical formula

Chemical formula

Chemical formula

[0134] The surfactant (a) can be produced, for example, by the production method described in International Publication No. 2020 / 022355.

[0135] The surfactant (b) can be produced, for example, by the production method described in International Publication No. 2020 / 022355.

[0136] The surfactant (c) can be produced, for example, by the production method described in International Publication No. 2020 / 022355.

[0137] The surfactant (d) can be produced, for example, by the production method described in International Publication No. 2020 / 022355.

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

[0139] It is also preferable that the specific hydrocarbon surfactant is a carboxylic acid type hydrocarbon surfactant. The carboxylic acid type hydrocarbon surfactant is not limited as long as it has a carboxy group (-COOH) or a group in which 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-mentioned specific hydrocarbon surfactants, a hydrocarbon 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. Preferably, the proportion of hydrogen atoms bonded to carbon atoms in the carboxylic acid type hydrocarbon 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).

[0140] Preferably, as the carboxylic acid type hydrocarbon 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.

[0141] 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. It is preferable that the proportion of hydrogen atoms bonded to carbon atoms in the sulfonic acid type hydrocarbon 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).

[0142] The TFE-based polymer composition of the present disclosure can be efficiently produced by using at least one of the above-mentioned specific hydrocarbon surfactants. Further, the TFE-based 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 can remain in a molded article made of a TFE-based polymer or the like.

[0143] 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.

[0144] 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. Preferably, 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).

[0145] Cationic surfactants usually have a positively charged hydrophilic moiety such as alkylated ammonium bromide or other alkylated ammonium halides, and a hydrophobic moiety such as a long-chain fatty acid. Preferably, 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).

[0146] Anionic surfactants usually have a hydrophilic moiety such as carboxylate, sulfonate or sulfate, and a hydrophobic moiety which is a long-chain hydrocarbon moiety such as alkyl. Preferably, 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).

[0147] Nonionic surfactants usually do not contain a charged group and have a hydrophobic moiety which is a long-chain hydrocarbon. The hydrophilic moiety of nonionic surfactants contains water-soluble functional groups such as a chain of ethylene ethers derived from polymerization with ethylene oxide. Preferably, the proportion of hydrogen atoms bonded to carbon atoms substituted with fluorine atoms in the above nonionic surfactant is 50% or less, more preferably less than 25%, still more preferably 10% or less, and most preferably 0% (not substituted with fluorine atoms at all).

[0148] Examples of compounds having other surface active properties 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. Specific examples include those represented by CH3-(CH2) n -L-M (wherein n is an integer of 6 to 17; L and M are the same as above) typified by lauric acid. 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 active properties 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 imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group (preferably an organic group not containing fluorine), -ArSO3 - is an arylsulfonate. ) Also included are anionic surfactants represented by 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, 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. An imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have a substituent, R 5 is H or an organic group (preferably an organic group not containing fluorine). -ArSO3 - is an arylsulfonate. ) Also included are anionic surfactants represented by

[0149] Examples of siloxane hydrocarbon surfactants include those described in Silicone Surfactants, R.M. Hill, Marcel Dekker, Inc., ISBN: 0-8247-00104. The structure of siloxane surfactants includes distinct hydrophobic and hydrophilic portions. The hydrophobic portion contains one or more dihydrocarbylsiloxane units, where the substituents on the silicone atom are entirely hydrocarbon. When the carbon atoms of the hydrocarbyl group can be substituted by a halogen such as fluorine, these siloxane surfactants can be regarded as hydrocarbon surfactants in the sense that they are completely substituted by hydrogen atoms, that is, the monovalent substituents on the carbon atoms of the hydrocarbyl group are hydrogen. It is preferable that the ratio of the hydrogen atoms bonded to the carbon atoms of the above siloxane surfactant 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).

[0150] The siloxane hydrocarbon surfactant is also disclosed in U.S. Patent No. 6,841,616.

[0151] As other compounds having surfactant properties, an anionic hydrocarbon surfactant is preferably used. As the anionic hydrocarbon surfactant, those described above can be adopted. For example, the following hydrocarbon surfactants can be preferably adopted.

[0152] 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.) The compound (α) represented by is mentioned. As the organic group of R 101 , an alkyl group is preferable. As R 101 , H or an organic group having 1 to 10 carbon atoms is preferable, H or an organic group having 1 to 4 carbon atoms is more preferable, and H or an alkyl group having 1 to 4 carbon atoms is still more preferable. From the viewpoint of surfactant properties, R 100Preferably, the carbon number is 2 or more, and more preferably 3 or more. Also, from the viewpoint of water solubility, R 100 preferably has 29 or less carbon atoms, and more preferably 23 or less carbon atoms. Examples of the metal atom of M include alkali metals (Group 1) and alkaline earth metals (Group 2), and Na, K, or Li is preferable. As M, H, a metal atom, or NR 101 4 is preferable, H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 101 4 is more preferable, H, Na, K, Li, or NH4 is even more preferable, Na, K, or NH4 is even more preferable, Na or NH4 is particularly preferable, and NH4 is most preferable.

[0153] Examples of the compound (α) 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 the carbon number 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 -COOM (wherein n is an integer of 2 to 28. M is the same as above) are included.

[0154] 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 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 101is 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 As the organic group of, an alkyl group is preferable. 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 performance, R 100 preferably has 2 or more carbon atoms, more preferably 3 or more carbon atoms. Also, from the viewpoint 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 above include alkali metals (Group 1), alkaline earth metals (Group 2), etc., and Na, K, or Li is preferable. As M, H, a metal atom, or NR 101 4 is preferable, H, an alkali metal (Group 1), an alkaline earth metal (Group 2), or NR 101 4 is more preferable, H, Na, K, Li, or NH4 is still more preferable, Na, K, or NH4 is even more preferable, Na or NH4 is particularly preferable, and NH4 is most preferable.

[0155] Examples of the compound (β) above include 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 carbon number is 3 or more, it may contain a monovalent or divalent heterocyclic ring or may form a ring. M is the same as above.). An anionic surfactant represented by this is also included. Specifically, CH3-(CH2) n -SO3M (wherein n is an integer from 2 to 28. M is the same as above) is included.

[0156] Examples of the anionic hydrocarbon surfactant above include 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.

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

[0158] Compound I has the following formula:

Chemical formula

[0159] Compound I has the following formula II:

Chemical formula

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

[0161] Compound I is represented by the following formula III: [Chemical formula] (In the formula, R 3 , R 4’ , and R 4’’ are the same or different and are hydrogen or a saturated or unsaturated, acyclic or cyclic aliphatic group having 4 to 16 carbon atoms, and the percentage of the total of CH3 with respect to the total of CH3, CH2, and CH groups in the R 3 , R 4’ , and R 4’’ groups is at least about 70%. However, at least one of R 3 , R 4’ , and R 4’’ is not hydrogen, and when R 4’ and R 4’’ are hydrogen, R 3 is not hydrogen, and when R 3 is hydrogen, R 4’ and R 4’’ are not hydrogen. Y + is hydrogen, ammonium, quaternary ammonium, nitrogen heterocycle, alkali metal, or alkaline earth metal. It is also preferably the compound III represented by the formula ().

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

[0163] Even when the above-mentioned specific hydrocarbon surfactant is not used, the TFE-based polymer composition of the present disclosure can be obtained by a production method including a polymerization step of polymerizing tetrafluoroethylene alone or tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene in an aqueous medium having a pH of 4.0 or higher in the presence of a hydrocarbon surfactant and a polymerization initiator to obtain a TFE-based polymer. Conventionally, since a polymerization initiator showing acidity was used for the polymerization step for producing a TFE-based polymer, the pH of the aqueous medium used for the polymerization was less than 4.0. As a result of intensive studies by the present inventors, it was unexpectedly found that by setting the pH of the aqueous medium used for the polymerization to 4.0 or higher, 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, tetrafluoroethylene alone or tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene are polymerized in an aqueous medium having a pH of 4.0 or higher. The above pH may be 4.0 or higher, preferably more than 4.0, more preferably 4.5 or higher, still more preferably 5.0 or higher, still more preferably 5.5 or higher, particularly preferably 6.0 or higher, particularly preferably 6.5 or higher, particularly preferably 7.0 or higher, particularly preferably 7.5 or higher, and particularly preferably 8.0 or higher. The upper limit value of the above pH is not particularly limited, but may be, for example, 13.0 or lower. From the viewpoint of corrosion of the polymerization tank, it is preferably 12.0 or lower, more preferably 11.5 or lower, and more preferably 11.0 or lower. The above pH can be measured by a pH meter.

[0164] The TFE-based polymer composition of the present disclosure can be obtained by a polymerization step of polymerizing tetrafluoroethylene alone or tetrafluoroethylene and a modified monomer copolymerizable with the tetrafluoroethylene in an aqueous medium in the presence of an anionic hydrocarbon surfactant and a polymerization initiator even when the above specific hydrocarbon surfactant is not used. The hydrocarbon surfactant can also be obtained by a step including 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 the polymerization stability is improved by including a salt of the anionic hydrocarbon surfactant, 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, and the emulsifying performance is easily exhibited. The above anionic hydrocarbon surfactant will be described later. The fact that the anionic hydrocarbon surfactant contains 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 above 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 is an imidazolium which may have a substituent, a pyridinium which may have a substituent, or a phosphonium which may have 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 an 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, the sample solution temperature is kept at 25 °C, and the temperature of the cell of the pH meter is also made the same, and then the conductivity is measured.

[0165] The TFE-based 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 for a polymerization initiator. The above addition step is performed during the step of performing the above-described emulsion polymerization in an aqueous medium. By adding a radical scavenger or a decomposition agent for a polymerization initiator, the radical concentration during polymerization can be adjusted. From the viewpoint of reducing the radical concentration, a radical scavenger is preferred.

[0166] As the above radical scavenger, a compound having no restart ability after addition or chain transfer to free radicals in the polymerization system is used. Specifically, a compound having a function of easily causing a chain transfer reaction with a primary radical or a growing radical and then generating a stable radical that does not react with a monomer, or easily causing 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 a chain transfer constant and a restart efficiency, but among chain transfer agents, those having a restart efficiency of almost 0% are called radical scavengers. The above radical scavenger can also be a compound, for example, 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) (= chain transfer rate constant (kc) / polymerization rate constant (kp)) with TFE at the polymerization temperature greater than 0.1. For the above compound, it is more preferable that the chain transfer constant (Cs) is 0.5 or more, still more preferable that it is 1.0 or more, even more preferably that it is 5.0 or more, and particularly preferably that it is 10 or more.

[0167] 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 preferable. 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 preferable, unsubstituted phenol or polyhydric phenol is more preferable, and hydroquinone is still more preferable.

[0168] 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 concentration of the polymerization initiator. 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), particularly 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).

[0169] 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 with respect to the amount of the oxidizing agent combined as the polymerization initiator (redox initiator described later). Preferably it is 25 to 150% by mass, and still 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 concentration of the polymerization initiator. 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).

[0170] 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.

[0171] 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.

[0172] The above polymerization step may further be one in which tetrafluoroethylene is polymerized in the presence of a nucleating agent.

[0173] As the above nucleating agent, 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.

[0174] As the above fluoropolyether, perfluoropolyether is preferred.

[0175] 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.)

[0176] 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.

[0177] The above fluoropolyether acid or its salt can have any chain structure in which the 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.

[0178] 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.

[0179] 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.

[0180] Fluoropolyethers having acid groups at one or both ends have at least two ether oxygens, preferably at least four ether oxygens, and even more preferably at least six ether oxygens. Preferably, at least one of the fluorocarbon groups separating the ether oxygens, more preferably at least two of such fluorocarbon groups, has two or three carbon atoms. Even more preferably, at least 50% of the fluorocarbon groups separating the ether oxygens have two or three 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.

[0181] 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.

[0182] The amount of the above fluoropolyether is preferably 5 to 3000 ppm with respect to the aqueous medium, more preferably 5 to 2000 ppm. The even more preferable lower limit is 10 ppm, and the even more preferable upper limit is 100 ppm.

[0183] Examples of the nonionic surfactant as the above nucleating agent include the nonionic surfactants described above, and a nonionic surfactant not containing fluorine is preferable. 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 the formula 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. 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.

[0184] The polyoxyalkylene chain may consist of oxyethylene and oxypropylene. It is a polyoxyalkylene chain composed of an average repeat number of 5 to 20 of oxyethylene groups and an average repeat 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 repeat 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 repeat number of 7 to 12 of oxyethylene groups and an average repeat number of 0 to 2 of oxypropylene groups is preferred. Particularly, when A 1 has an average of 0.5 to 1.5 oxypropylene groups, it has good low foaming property and is preferred.

[0185] 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.

[0186] 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 ethers 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.

[0187] 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).

[0188] 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 can be mentioned. Specifically, as the above polyoxyethylene alkylphenyl ether-based nonionic compound, Triton (registered trademark) X-100 (product name, manufactured by Dow Chemical Company) and the like can be mentioned.

[0189] As other nonionic surfactants, a bifunctional block copolymer supplied as the Pluronic® R series from BASF, a tridecyl alcohol alkoxylate supplied as the Iconol® TDA series from BASF Corporation, a hydrocarbon-containing siloxane surfactant, preferably a hydrocarbon surfactant, wherein when the above hydrocarbyl group can be substituted by a halogen such as fluorine, it is completely substituted by a hydrogen atom, whereby these siloxane surfactants can also be regarded as hydrocarbon surfactants, that is, the monovalent substituent on the hydrocarbyl group is hydrogen.

[0190] In addition, 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.

[0191] As the stabilization aid, paraffin wax, fluorine-based oil, fluorine-based solvent, silicone oil and the like 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 a saturated hydrocarbon having 12 or more carbon atoms is preferable. The melting point of the paraffin wax is usually preferably 40 to 65 °C, more preferably 50 to 65 °C.

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

[0193] In the above manufacturing method, the emulsion polymerization can be carried out by charging an aqueous medium, the above hydrocarbon surfactant, monomers, and other additives as required into a polymerization reactor, stirring the contents of the reactor, maintaining the reactor at a predetermined polymerization temperature, then adding a predetermined amount of a polymerization initiator, and starting 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.

[0194] In the above emulsion polymerization, the polymerization temperature and 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.

[0195] 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 relative to the total of the aqueous medium and the TFE-based polymer. In the above emulsion polymerization, the amount of the hydrocarbon surfactant at the start of polymerization is preferably 1 ppm or more based on 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 100000 ppm and more preferably 50000 ppm. By setting the amount of the hydrocarbon surfactant at the start of polymerization within the above range, an aqueous dispersion with a smaller average primary particle diameter and better stability can be obtained.

[0196] The above polymerization initiator is not particularly limited as long as it can generate radicals within 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.

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

[0198] The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide. 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.

[0199] 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.

[0200] For example, when polymerization is carried out 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.

[0201] 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.

[0202] 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 described in 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 capable of making 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.

[0203] 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 a 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 a 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.

[0204] Specifically, as the redox initiator, it is preferably 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.

[0205] By using a redox initiator in the above polymerization step, the molecular weight of the obtained TFE-based polymer can be increased. Therefore, the SSG can be reduced, and it can be made stretchable. In addition, by using a redox initiator in the above polymerization step, the number of particles of the TFE-based polymer generated 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 all at once at the initial stage of polymerization, or the reducing agent may be added all at once at the initial stage of polymerization and the oxidizing agent may be added continuously, or the oxidizing agent may be added all at once at the initial stage 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 above polymerization step, the polymerization temperature is preferably 100°C or lower, more preferably 95°C or lower, and even more preferably 90°C or lower. Also, it is preferably 10°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher.

[0206] 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 relative to the water concentration) or more. 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.

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

[0208] 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.

[0209] Examples of the above chain transfer agent include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, dimethyl succinate, and various halogenated hydrocarbons such as isopentane, methane, ethane, propane, isobutane, methanol, ethanol, isopropanol, acetone, various mercaptans, carbon tetrachloride, and cyclohexane.

[0210] 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), and compounds represented thereby can be mentioned. By using a bromine compound or an iodine compound, iodine or bromine is introduced into the polymer and functions as a crosslinking point.

[0211] Examples of 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-diiodoperfluorhexane, 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-substituted products of benzene, diiodomonobromo-substituted products, and (2-iodoethyl) and (2-bromoethyl) substituted products, etc. These compounds may be used alone or in combination with each other.

[0212] 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.

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

[0214] The above chain transfer agent may be added to the reaction vessel all at once 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 portions during polymerization, or may be added continuously during polymerization.

[0215] 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, a compound (1) and / or (2), and an aqueous medium. The solid content concentration of the above aqueous dispersion is not limited, but 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, still more preferably 1.0% by mass or less, further preferably 0.8% by mass or less, still further preferably 0.7% by mass or less, and particularly preferably 0.6% by mass or less, based on the finally obtained TFE-based polymer.

[0216] The TFE-based polymer used as a raw material for the above TFE-based polymer composition preferably has an average primary particle diameter of 150 nm or more because a composite sheet having higher strength and excellent homogeneity can be obtained. More preferably, it is 180 nm or more, still more preferably 210 nm or more, and particularly preferably 220 nm or more. The larger the average primary particle diameter of the TFE-based polymer, the more the increase in extrusion pressure can be suppressed when extrusion molding is performed using the powder, and the moldability is also excellent. The upper limit is not particularly limited, but may be 500 nm. From the viewpoint of productivity in the polymerization step, the upper limit is preferably 350 nm.

[0217] The average primary particle diameter can be determined by preparing a calibration curve between the transmittance of incident light at 550 nm per unit length of an aqueous dispersion with a polymer concentration adjusted to 0.22% by mass, prepared using an aqueous dispersion of a TFE-based polymer obtained by polymerization, and the average primary particle diameter determined by measuring the fixed-direction diameter in a transmission electron micrograph, measuring the transmittance for the aqueous dispersion to be measured, and then determining based on the calibration curve.

[0218] The mixture of the TFE-based polymer and the conductive carbon material mixed in the liquid medium by the above step (A) is preferably dried by spray drying (step (B)) to remove the liquid medium. Examples of the drying method include a shelf dryer, a vacuum dryer, a freeze dryer, a hot air dryer, a drum dryer, a spray dryer, etc. Particularly preferred is spray drying. Spray drying is a technique for producing a dry powder by spraying a mixture of a liquid and a solid into a gas and rapidly drying it. Thereby, a powder composition in which the TFE-based polymer and the conductive carbon material are uniformly mixed can be obtained. Spray drying is a generally well-known technique and can be carried out by any known apparatus using a general method. The above step (B) can be carried out by a general method using a known general apparatus. The drying temperature is preferably in the range of, for example, 100°C or higher and 250°C or lower. At 100°C or higher, the solvent can be sufficiently removed, and at 250°C or lower, the energy consumption can be further reduced, which is preferable. The drying temperature is more preferably 110°C or higher and more preferably 220°C or lower. Also, the supply liquid amount may be in the range of, for example, 0.1 L / h or higher and 2 L / h or lower, although it depends on the scale to be produced. Also, the nozzle size for spraying the preparation solution may be in the range of, for example, 0.5 mm or more and 5 mm or less in diameter, although it depends on the scale to be produced.

[0219] The TFE-based polymer composition of the present disclosure is used as a binder for electrochemical devices. In the above-mentioned binder for electrochemical devices, the TFE-based polymer composition of the present disclosure may be used alone or in combination with other materials, but it is preferably used substantially alone, and more preferably used alone. Here, using the TFE-based polymer composition of the present disclosure substantially alone means using it so that the amount of the TFE-based polymer composition in the binder for electrochemical devices falls within the range described below.

[0220] The present disclosure also provides a binder for electrochemical devices consisting essentially of only a TFE-based polymer composition, wherein the TFE-based polymer composition contains a TFE-based polymer, at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and a conductive carbon material, and the amount of the TFE-based polymer relative to the solid content in the TFE-based polymer composition is 10% by mass or more. 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.)

[0221] The binder of the present disclosure can reduce the resistance of the pharmaceutical sheet by including a specific TFE-based polymer composition. Further, when in powder form, the fluidity can also be improved. The binder of the present disclosure can also be used dry, so it is not necessary to use a large amount of dispersion media such as water or organic solvents, and a wide selection of electrode active materials and solid electrolytes to be combined can be made, which is advantageous in the production process. Further, the processes and costs due to the use of the dispersion medium can be reduced. Furthermore, since the binder of the present disclosure has excellent adhesion to the active material and electrolyte, the amount used can be reduced.

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

[0223] The binder of the present disclosure consists essentially of only the above TFE-based polymer composition. Thereby, the effects of the above TFE-based polymer composition can be significantly exerted. Consisting essentially of only the above TFE-based polymer composition means that the content of the above TFE-based polymer composition is 95.0% by mass or more with respect to the above binder. The content of the above TFE-based 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 with respect to the above binder. It is also preferable that the binder of the present disclosure consists of only the above TFE-based polymer composition.

[0224] 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 content of the above organic solvent 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.

[0225] The form of the binder of the present disclosure is preferably powder, but may also be in a form other than powder, for example, a dispersion or a molded body. Examples of the molded body include a sheet, a pellet, a rod shape, etc.

[0226] 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, a redox capacitor, etc. Examples of the hybrid capacitor include a sodium ion capacitor, a lithium ion capacitor, a magnesium ion capacitor. Among these, an electric double layer capacitor is particularly preferable.

[0227] The binder of the present disclosure can be suitably used as a battery binder, and can be particularly suitably used as a binder for secondary batteries such as lithium ion batteries. Among them, it is preferably used as a binder for lithium ion secondary 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.

[0228] The present disclosure also provides an electrode binder including the above-described TFE-based polymer composition or binder of the present disclosure and an electrode active material. When the electrode binder of the present disclosure is used, a binder sheet with low resistance can be obtained. In addition, since good electron conduction can be maintained even with a small amount of a conductive carbon material (conductive aid), more materials for improving the electrochemical device properties such as active materials and electrolytes can be added.

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

[0230] The positive electrode active material is not particularly limited as long as it can electrochemically 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, alkali metal-containing transition metal phosphate compounds, etc. 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, etc. 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.

[0231] Examples of the alkali metal-containing transition metal composite oxide include, for example, 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) an alkali metal-manganese spinel composite oxide (such as lithium-manganese spinel composite oxide), Formula: MNi 1-c M 2 cO2 (wherein M is at least one metal selected from the group consisting of Li, Na, and K; 0 ≦ c ≦ 0.5; M 2 is at least one metal selected from the group consisting of Fe, Co, Mn, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge), an alkali metal-nickel composite oxide (such as lithium-nickel composite oxide), or Formula: MCo 1-d M 3 d O2 (wherein M is at least one metal selected from the group consisting of Li, Na, and K; 0 ≦ d ≦ 0.5; M 3 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), 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.

[0232] Among them, from the viewpoint of being able to provide a secondary battery with high energy density and high output, 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 it is preferable to be a compound represented by the following general formula (3). MNi h Co i Mn j M 5 k O2(3) (wherein M is at least one metal selected from the group consisting of Li, Na, and K, and M 5represents at least one selected from the group consisting of Fe, Cu, Zn, Al, Sn, Cr, V, Ti, Mg, Ca, Sr, B, Ga, In, Si, and Ge, and (h + i + j + k) = 1.0, 0 ≦ h ≦ 1.0, 0 ≦ i ≦ 1.0, 0 ≦ j ≦ 1.5, 0 ≦ k ≦ 0.2.)

[0233] Examples of the alkali metal-containing transition metal phosphate compound include 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 even more preferably Li. That is, as the alkali metal-containing transition metal phosphate compound, a lithium-containing transition metal phosphate compound is preferred.)

[0234] As the transition metal of the lithium-containing transition metal phosphate compound, V, Ti, Cr, Mn, Fe, Co, Ni, Cu, etc. are preferred. 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 lithium-containing transition metal phosphate compound, those having an olivine-type structure are preferred.)

[0235] Examples of other positive electrode active materials include lithium-nickel-based composite oxides. Examples of the lithium-nickel-based composite oxide include the following general formula (5): Li y Ni1-x M x O2(5) (wherein x satisfies 0.01 ≦ x ≦ 0.7, y satisfies 0.9 ≦ y ≦ 2.0, and M represents a metal atom (excluding Li and Ni)) is preferred as the cathode active material.

[0236] Other cathode active materials include 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. may also be mentioned. In particular, cathode active materials such as M2MnO3, MNi 0.5 Mn 1.5 O2 are preferred in that their crystal structures do not collapse even when the secondary battery is operated at a voltage exceeding 4.4 V or at a voltage of 4.6 V or higher. Therefore, an electrochemical device such as a secondary battery using a cathode material containing the cathode active material exemplified above is preferred because the residual capacity hardly decreases, the resistance increase rate hardly changes, and the battery performance does not deteriorate even when operated at a high voltage, even when stored at a high temperature.

[0237] Other cathode active materials include solid solution materials such as 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).

[0238] Examples of the solid solution material include alkali metal manganates represented by the general formula Mx[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 7It 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, Li 1.2 Mn 0.5 Co 0.14 Ni 0.14 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.

[0239] 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 preferably used by mixing with the above positive electrode active material. The amount of lithium phosphate used is preferably at least 0.1% by mass, more preferably at least 0.3% by mass, still more preferably at least 0.5% by mass, and preferably at most 10% by mass, more preferably at most 8% by mass, still more preferably at most 5% by mass, based on the total of the above positive electrode active material and lithium phosphate.

[0240] The shape of the particles of the positive electrode active material includes those conventionally used, such as massive, polyhedral, spherical, ellipsoidal, plate-like, needle-like, columnar, etc. Also, the primary particles may aggregate to form secondary particles.

[0241] The median diameter d50 of the particles of the positive electrode active material (when primary particles aggregate to form secondary particles, it is the secondary particle diameter) 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 below the above lower limit, it may not be possible to obtain a product with a high tap density. 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 fillability during the production of the positive electrode can be further improved.

[0242] 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 ultrasonic dispersion for 5 minutes, the measurement refractive index 1.24 is set for measurement.

[0243] 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. 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 surface area meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken), after pre-drying the sample at 150 °C for 30 minutes under nitrogen flow, and then using a nitrogen-helium mixed gas accurately adjusted so that the relative pressure value of nitrogen with respect to atmospheric pressure becomes 0.3.

[0244] 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 increases, and the diffusion of lithium ions between the electrode binder and the electrolyte can be made faster. As a result, the output performance of the battery can be improved.

[0245] 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 combinations with O2, combinations of 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.

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

[0247] The negative electrode active material is not particularly limited. For example, 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 those containing carbonaceous materials such as hardly graphitizable carbon, silicon and silicon-containing compounds such as silicon alloys, Li4Ti5O 12Any selected from the above, or a mixture of two or more types, 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.

[0248] In the present disclosure, it is preferable that the negative electrode active material used contains silicon as a constituent element. By using a material containing silicon as a constituent element, a high-capacity battery can be manufactured.

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

[0250] The physical properties of the silicon-containing particles 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 even more preferably 0.5 μm or more. The upper limit is more preferably 30 μm or less, and even more preferably 20 μm or less. The above average particle size is represented by the weight average particle size in the particle size distribution measurement by the laser diffraction method.

[0251] 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, if it is 100 m 2 / g or less, the ratio of silicon dioxide on the particle surface will not increase, and there is no risk that the battery capacity will decrease when used as a negative electrode material for a lithium ion secondary battery.

[0252] By carbon coating the silicon-containing particles, conductivity is imparted, and improvement in battery characteristics can be observed. 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.

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

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

[0255] The content of the thermoplastic polymer 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 usually 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 polymer, the mechanical strength of the electrode can be improved. Also, if it exceeds this range, problems such as a decrease in the proportion of the electrode active material in the electrode binder and a decrease in the capacity of the battery, or an increase in the resistance between the active materials may occur.

[0256] In the electrode binder 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 binder. Also, it 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 binder active material cannot be sufficiently retained, resulting in insufficient mechanical strength of the electrode binder 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 adhesion, even with a small content, the electrode active material can be sufficiently retained.

[0257] In the electrode binder of the present disclosure, the binder component preferably consists essentially of only the above TFE-based polymer composition, and more preferably consists of only the above TFE-based polymer composition. That the binder component consists essentially of only the above TFE-based polymer composition means that the content of the above TFE-based polymer composition in the binder component constituting the electrode binder is 95.0% by mass or more with respect to the above binder component. The content of the above TFE-based polymer composition is preferably 98.0% by mass or more, more preferably 99.0% by mass or more, even more preferably 99.5% by mass or more, particularly preferably 99.9% by mass or more, and most preferably 99.95% by mass or more with respect to the above binder component.

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

[0259] 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 used in a secondary battery, the electrode binder of the present disclosure is usually used in the form of a sheet.

[0260] The above electrode mixture 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, and even more preferably 50 μm or more.

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

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

[0263] In the above step (2), at the stage where a shearing force is applied while mixing the composition for electrode production, the resulting composition for electrode production exists in a state where the electrode active material, binder, etc. are simply mixed and have no fixed shape. Specific mixing methods include 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.

[0264] In the above step (2), the mixing conditions may be appropriately set for the rotation speed and the mixing time. For example, the rotation speed is preferably 2200 rpm or less. Preferably it is 10 rpm or more, more preferably 15 rpm or more, and still more preferably 20 rpm or more. Also, it is preferably 2000 rpm or less, more preferably 1800 rpm or less, and still more preferably in the range of 1500 rpm. If it is below the above range, it will take time for mixing and affect productivity. Also, if it exceeds, fibrillation may progress excessively, resulting in an electrode binder sheet with inferior strength and flexibility.

[0265] In the above step (3), forming into a bulk shape means making the composition for electrode production into one mass. Specific methods for forming into a bulk shape include extrusion molding, press molding, etc. Also, "bulk shape" is not particularly defined by shape, and it may be any state of being in one lump, including forms such as rod shape, sheet shape, spherical shape, cube shape, etc. The size of the above lump preferably has a diameter or the smallest side of its cross-section of 10000 μm or more. More preferably, it is 20000 μm or more.

[0266] Specific rolling methods in the above step (4) include methods of rolling using a roll press, a flat press, a calender roll, etc.

[0267] Also, after step (4), it is also preferable to have a step (5) 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 (5). In this way, by rolling the rolled sheet in stages little by little instead of thinning it all at once, the flexibility becomes better. The number of times for step (5) 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 a rolling sheet therebetween to process it into a thinner sheet shape. It is desirable to heat during rolling. The lower limit of the temperature range is preferably 40 degrees or more, more preferably 50 degrees or more, and still more preferably 60 degrees or more. The upper limit is preferably 300 degrees or less, more preferably 250 degrees or less, and still more preferably 200 degrees or less. By heating, the sheet softens and can be easily rolled.

[0268] Also, from the viewpoint of adjusting the fibril diameter, after step (4) or step (5), it is also preferable to have a step (6) of crushing the rolling sheet, then forming it into a bulk shape again, and rolling it into a sheet shape. It is also preferable to repeat step (6). The number of times of step (6) is preferably 1 or more and 12 or less, and more preferably 2 or more and 11 or less.

[0269] In step (6), specific methods of crushing the rolling sheet and forming it into a bulk shape include a method of folding the rolling sheet, a method of forming it into a rod or thin film sheet shape, a method of chipping, etc. In the present disclosure, "crushing" means changing the form of the rolling sheet obtained in step (4) or step (5) into another form in order to roll it into a sheet shape in the next step, and includes cases such as simply folding the rolling sheet.

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

[0271] In the above steps (4), (5) or (6), the rolling ratio is preferably 10% or more, more preferably 20% or more, and is 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 with the increase in the number of rolling passes, which will affect productivity. If it exceeds the range, fibrillation may progress excessively, resulting in an electrode binder sheet with inferior strength and flexibility. Here, the rolling ratio 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 composition for electrode production or a sheet-like composition for electrode production. The thickness of the sample refers to the thickness in the direction where the load is applied during rolling.

[0272] 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 to form a powder; (a2) a step of mixing the powdery electrode production composition obtained in step (a1) to prepare an electrode binder It can also be preferably manufactured by a manufacturing method characterized by including.

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

[0274] 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 a case of (a1), it is preferable to perform mixing and homogenization while suppressing fibrillation. The mixing in the subsequent step (a2) is preferably carried out at a temperature of 30°C or higher to promote fibrillation.

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

[0276] The mixing in the above step (a) is preferably carried out while applying a shearing force. 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.

[0277] The mixing conditions may be appropriately set for the rotation speed and the mixing time. For example, the rotation speed is preferably set to 15,000 rpm or less. Preferably it is 10 rpm or more, more preferably 50 rpm or more, and even more preferably 100 rpm or more, and also preferably 12,000 rpm or less, more preferably 10,000 rpm or less, and even more preferably in the range of 8,000 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 poor strength. In step (a1), it is preferable to carry out with a shearing force weaker than that in step (a2). Also, in step (a1), it is desirable to carry out in a shorter time than in step (a2).

[0278] In the above step (a2), it is preferable that the composition for electrode production 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 composition for electrode production obtained in the above step (a1) to prepare a paste.

[0279] The above 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).

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

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

[0282] The above composition for electrode production and the electrode binder sheet preferably do not substantially contain a liquid medium. In the conventional method for forming an electrode binder, a slurry in which a powder as an electrode binder component is dispersed is generally prepared using a solvent in which a binder is dissolved, and the electrode binder sheet is prepared by applying and drying the slurry. In the conventional method, since the binder is dissolved, it takes processing time to prepare the slurry. In addition, a large amount of energy is required to sufficiently dry the solvent after coating. By using a powdery binder with little moisture without using a solvent when forming the composition for electrode production and the electrode binder sheet, the burden on the manufacturing process can be reduced without causing deterioration to battery components such as the active material and the electrolyte.

[0283] Step (b) is calendaring or extrusion. Calendaring and extrusion can be carried out by well-known methods. Thereby, it can be formed into the shape of an electrode mixture sheet. Step (b) preferably includes: (b1) a step of forming the electrode mixture obtained in step (a) into a bulk shape; and (b2) a step of calendaring or extrusion-molding the bulk electrode mixture.

[0284] Forming into a bulk shape means making the electrode mixture into one mass. Specific methods of forming into a bulk shape include extrusion molding, press molding, etc. Also, the "bulk shape" is not particularly specified in terms of shape, and it only needs to be in a state of being one mass, including forms such as rod shape, sheet shape, spherical shape, cube shape, etc. The size of the above mass preferably has a diameter or the smallest side of its cross-section of 10000 μm or more. More preferably, it is 20000 μm or more.

[0285] As a specific method of calendaring or extrusion molding in step (b2), there is a method of rolling the electrode mixture using a roll press machine, a calendar roll machine, etc.

[0286] Step (b) is preferably carried out at 30 to 200 °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.

[0287] And since calendaring or extrusion is subjected to a shearing force, PTFE fibrillates thereby and molding is performed.

[0288] After step (b), it is also preferable to have step (c) of applying a greater load to the obtained rolled sheet and further rolling it into an even thinner sheet shape. It is also preferable to repeat step (c). In this way, by rolling the rolled sheet in stages little by little instead of thinning it all at once, the flexibility becomes better. The number of times of step (c) is preferably 2 or more and 10 or less, more preferably 3 or more and 9 or less. Specific rolling methods include, for example, a method of rotating two or more rolls and passing a rolled sheet therebetween to process it into a thinner sheet shape.

[0289] Also, from the viewpoint of adjusting the sheet strength, it is also preferable to have a step (d) of crushing the rolled sheet and then reshaping it into a bulk shape and rolling it into a sheet shape after step (b) or step (c). It is also preferable to repeat step (d). The number of times of step (d) is preferably 1 or more and 12 or less, more preferably 2 or more and 11 or less.

[0290] In step (d), specific methods of crushing the rolled sheet and shaping it into a bulk shape include a method of folding the rolled sheet, or a method of shaping it into a rod or thin film sheet shape, a method of chipping, etc. In the present disclosure, "crushing" means changing the form of the rolled sheet obtained in step (b) or step (c) into 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.

[0291] 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).

[0292] In the above steps (b), (c) or (d), the rolling rate is preferably 10% or more, more preferably 20% or more, and is also 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 times increases, which will affect productivity. Also, if it exceeds the range, fibrillation may progress excessively, resulting in an electrode binder sheet with inferior strength and flexibility. The rolling ratio mentioned here refers to the reduction ratio of the thickness after processing to the thickness before the rolling process of the sample. The sample before rolling may be a bulk electrode preparation composition or a sheet electrode preparation 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 200°C or lower.

[0293] The above electrode binder sheet can be used as an electrode binder sheet for secondary batteries. It can be either the negative electrode or the positive electrode. In particular, the above electrode binder sheet is suitable for lithium-ion secondary batteries.

[0294] The present disclosure also provides an electrode comprising the above-described TFE-based polymer composition or binder of the present disclosure, an electrode active material, and a current collector. The electrode of the present disclosure has low resistance. Also, since good electron conduction can be maintained even when the amount of the conductive carbon material (conductive aid) is small, more materials for improving the electrochemical device characteristics such as the active material and the electrolyte can be added.

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

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

[0297] The above positive electrode is preferably composed of a current collector and an electrode binder 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, nickel, or metal materials such as their alloys; carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly aluminum or its alloy, are preferred.

[0298] The density of the positive electrode binder sheet is preferably 2.80 g / cm 3 or more, more preferably 3.00 g / cm 3More preferably, it is 3.20 g / cm or more. 3 or more, and preferably 3.80 g / cm or less. 3 More preferably, it is 3.75 g / cm or less. 3 Still more preferably, it is 3.70 g / cm or less. 3 It is in the range below. 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.

[0299] 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 from the thickness of the positive electrode 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 preferably 500 μm or less, more preferably 450 μm or less.

[0300] 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; carbon materials such as carbon cloth and carbon paper. Among them, metal materials, particularly copper, nickel, or alloys thereof, are preferable.

[0301] The density of the negative electrode mixture sheet is preferably 1.3 g / cm or more. 3 More preferably, it is 1.4 g / cm or more. 3 Still more preferably, it is 1.5 g / cm or more. 3 and preferably 2.0 g / cm or less. 3 More preferably, it is 1.9 g / cm or less. 3 Still more preferably, it is 1.8 g / cm or less. 3 It is in the range below. 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.

[0302] The thickness of the negative electrode is not particularly limited. However, 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 from the overall thickness is preferably 10 μm or more, more preferably 20 μm or more, as a lower limit for one side of the current collector, and is preferably 500 μm or less, more preferably 450 μm or less.

[0303] Examples of the current collector shapes for the positive electrode and the negative electrode include metal foils, expanded metals, punched metals, foamed metals, etc. Among these, a metal foil is 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 is 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.

[0304] 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 still more preferably about 300 nm or more.

[0305] Also, it is preferable that a conductive assistant 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 assistant include carbon and noble metals such as gold, platinum, and silver. Carbon is particularly preferred in terms of its low weight.

[0306] The positive electrode and the negative electrode can be manufactured by conventional methods. For example, a method of laminating the above-mentioned electrode mixture sheet and the current collector via an adhesive and pressing them can be mentioned.

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

[0308] The secondary battery of the present disclosure may be a secondary battery using an electrolytic solution or a solid secondary battery. In the present 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.

[0309] For the secondary battery using the above electrolytic solution, an electrolytic solution, a separator, etc. used in known secondary batteries can be used. These will be described in detail below.

[0310] As the above electrolytic solution, a non-aqueous electrolytic solution is preferably used. As the non-aqueous electrolytic solution, a solution obtained by dissolving a known electrolyte salt in a known organic solvent for dissolving the electrolyte salt can be used.

[0311] 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, and ethyl methyl carbonate; one or more fluorine-based solvents such as fluoroethylene carbonate, fluoroether, and fluorinated carbonate can be used.

[0312] 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.

[0313] 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.

[0314] The secondary battery using the above electrolyte preferably further includes a separator. The material and shape of the 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 a porous sheet or a non-woven fabric form material having excellent liquid retention properties.

[0315] The above solid secondary battery is preferably an all-solid-state secondary battery. The above solid secondary battery is preferably a lithium-ion battery and is also preferably a sulfide-based solid secondary battery. The above 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 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 binder (preferably a binder sheet) containing the binder and solid electrolyte of the present disclosure, and a solid electrolyte layer (preferably a solid electrolyte layer sheet) containing the binder and solid electrolyte of the present disclosure are also preferred embodiments of the present disclosure.

[0316] The solid electrolyte used in the binder for the solid secondary battery 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.

[0317] The above 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, Li4-x Ge 1-x P x S4 (x = 0.6 to 0.8), Li 4+y Ge 1-y Ga y S4 (y = 0.2 to 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 SnP2S 12 Any one selected from the above, or a mixture of two or more types can be used.

[0318] 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.

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

[0320] 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 ccis at least one element selected from C, S, Al, Si, Ga, Ge, In, and Sn, where xc satisfies 0 ≦ xc ≦ 5, yc satisfies 0 ≦ yc ≦ 1, zc satisfies 0 ≦ zc ≦ 1, and nc satisfies 0 ≦ nc ≦ 6.), Li xd (Al, Ga) yd (Ti, Ge) zd Si ad P md O nd (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 greater than or equal to 0 and less than or equal to 0.1, and 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. may be mentioned. Further, ceramic materials obtained by substituting elements for LLZ are also known. For example, for LLZ, a part of it is substituted with Al to obtain Li 6.24 La3Zr2Al 0.24 O 11.98 , Li 6.25 Al 0.25 La3Zr2O 12 or Li substituted with Ta 6.6 La3Zr 1.6 Ta 0.4 O 12 , Li substituted with Nb 6.75 La3Zr 1.75 Nb 0.25 O 12 , etc. may be mentioned. In addition, there are also LLZ-based ceramic materials obtained by substituting at least one of Mg (magnesium) and A (A is at least one element selected from the group consisting of Ca (calcium), Sr (strontium), and Ba (barium)) for LLZ. Further, phosphorus compounds containing Li, P, and O are also desirable. For example, lithium phosphate (Li3PO4), LiPON obtained by substituting a part of the oxygen of lithium phosphate 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.) may be mentioned. Also, LiA 1 ON (A 1 is at least one selected from Si, B, Ge, Al, C, Ga, etc.) can also be preferably used. As specific examples, for example, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2, etc. may be mentioned.

[0321] The above oxide-based solid electrolytes preferably contain lithium. The oxide-based solid electrolytes containing lithium are used in solid-state batteries that use lithium ions as carriers, and are particularly preferable in terms of electrochemical devices having a high energy density.

[0322] 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 Al 0.3 Ti 1.7 (PO4)3 etc.), garnet type (Li7La3Zr2O 12 (LLZ) etc.), and the like. Among them, the garnet type is preferable.

[0323] 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.

[0324] 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, examples include cylindrical, rectangular, coin type, laminate type, and the like.

[0325] 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.

[0326] Although the embodiments have been described above, it will be understood that various changes in form and detail are possible without departing from the spirit and scope of the claims.

Examples

[0327] 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.

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

[0329] <Average primary particle diameter> It was 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 for 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.

[0330] <Polymer solid content concentration> 1 g of the aqueous dispersion of TFE-based polymer was dried in a forced-air dryer at 150 °C for 60 minutes, and the value obtained by expressing the ratio of the mass of the heat-resistant residue to the mass of the aqueous dispersion (1 g) as a percentage was adopted.

[0331] <Endothermic peak temperature> For a TFE-based polymer composition having no heating history at 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 were two or more minimum points in one melting peak, each was defined as the endothermic peak temperature.

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

[0333] <Moisture content> The mass of about 20 g of the TFE-based polymer composition was measured before and after heating at 150 °C for 2 hours, and calculated according to the following formula. Three samples were taken, calculated respectively, and the average was obtained and the average value was adopted. Moisture content (mass%) = [(mass of TFE-based polymer composition before heating (g)) - (mass of TFE-based polymer composition after heating (g))] / (mass of TFE-based polymer composition before heating (g)) × 100

[0334] <0.1% mass loss temperature> Weigh accurately about 10 mg of a TFE-based polymer composition that has no history of being heated to a temperature of 300 °C or higher, place it in a dedicated aluminum pan, and measure it using a TG·DTA (simultaneous differential thermal and thermogravimetric analyzer). The 0.1% mass loss temperature was defined as the temperature corresponding to the point where the weight decreased by 0.1 mass% when the temperature of the aluminum pan was increased from 25 °C to 600 °C at a rate of 10 °C / min under an air atmosphere.

[0335] <1.0% Mass Loss Temperature> Weigh accurately about 10 mg of a TFE-based polymer composition that has no history of being heated to a temperature of 300 °C or higher, place it in a dedicated aluminum pan, and measure it using 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 increased from 25 °C to 600 °C at a rate of 10 °C / min under an air atmosphere.

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

[0337] <Content of Specific Compounds Containing Fluorine> Measured under the following conditions using liquid chromatography-mass spectrometry.

[0338] 〔Method for Measuring the Content of the Compound Represented by 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 general formula (1). The obtained extract was appropriately concentrated by nitrogen purging to obtain a concentrated extract.

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

[0340] Calibration Curve of Perfluorooctanoic Acid Five standard methanol solutions of perfluorooctanoic acid with known concentrations ranging from 1 ng / mL to 100 ng / mL were prepared and measured using a liquid chromatography-mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). From the respective sample concentrations and peak integral values, a and b were determined using linear approximation according to the following relational expression (1). A = a×X + b (1) A: Peak area of perfluorooctanoic acid X: Concentration of perfluorooctanoic acid (ng / mL)

[0341] Measuring instrument configuration and LC-MS measurement conditions [Table 1]

[0342] MRM measurement parameters [Table 2]

[0343] Content of the compound represented by the general formula (1) having 4 or more and 20 or less carbon atoms contained in the extract Using a liquid chromatography-mass spectrometer, the compound represented by the general formula (1) 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 (1) for each carbon number was determined using the MRM method.

[0344] MRM measurement parameters [Table 3]

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

[0346] Content of the compound represented by the general formula (1) having (m + 1) carbon atoms contained in the composition The content of the compound represented by the general formula (1) having (m + 1) carbon atoms contained in the composition was determined by the following formula (4). YCm = XCm × 12.6 (4) YCm: Content (ppb relative to the TFE-based polymer) of the compound represented by the general formula (1) having (m + 1) carbon atoms contained in the composition The lower limit of quantification is 10 mass ppb.

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

[0348] Measurement of the content of the compound represented by the general formula (2) contained in the extract The content of the compound represented by the general formula (2) contained in the extract was determined by converting it to perfluorooctanesulfonic acid.

[0349] Calibration curve of perfluorooctanesulfonic acid Five levels of methanol standard solutions of perfluorooctanesulfonic acid with known concentrations of 1 ng / mL to 100 ng / mL were prepared and measured using a liquid chromatograph-mass spectrometer (Waters, LC-MS ACQUITY UPLC / TQD). From the respective sample concentrations and peak integration values, a and b were determined using linear approximation according to the following relational formula (1). A = a × X + b (1) A: Peak area of perfluorooctanesulfonic acid X: Concentration of perfluorooctanesulfonic acid (ng / mL)

[0350] Measuring instrument configuration and LC-MS measurement conditions

Table 4

[0351] MRM measurement parameters

Table 5

[0352] 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.

[0353] MRM measurement parameters

Table 6

[0354] The content of the compound represented by the general formula (2) with 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) with carbon number n in the extraction solution (ng / mL) ASn: Peak area of the compound represented by the general formula (2) with carbon number n in the extraction solution The limit of quantification in this measurement is 1 ng / mL.

[0355] Content of the compound represented by the general formula (2) with carbon number n contained in the composition The content of the compound represented by the general formula (2) having n carbon atoms 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 n carbon atoms contained in the composition (ppb relative to the TFE-based polymer) The lower limit of quantification is 10 mass ppb.

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

[0357] Preparation Example 1 0.273 g of lauric acid was added to 16 g of deionized water, and 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. The pH at this time was 9.6.

[0358] 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 SUS reactor with a stirrer having an internal volume of 3 L. 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, the pressure was increased 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 atmospheric pressure was reached. 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 from the reactor, cooled, paraffin wax was separated, and aqueous dispersion A of the TFE-based polymer was obtained. The pH of the obtained aqueous dispersion A of the TFE-based polymer was 8.8, the solid content concentration was 27.1 mass%, and the primary particle size was 220 nm.

[0359] The obtained aqueous dispersion A of the TFE-based polymer was diluted with deionized water to a solid content concentration of 13 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 dried at 210 °C for 18 hours to obtain a TFE-based polymer powder. The standard specific gravity of the obtained TFE-based polymer powder was 2.170, the thermal instability index was 44, the HFP content was 0.002 mass%, the 0.1 mass% reduction temperature was 391 °C, the 1.0 mass% reduction temperature was 491 °C, and the endothermic peak temperature was 342 °C. (H-(CF2) n -SO3)H content (where n is 4 to 20) was less than 10 mass ppb / polymer.

[0360] Production Example 1 Conductive carbon material and pure water were added, and using a planetary mixer (KK-100W, manufactured by KURABO), stirring was carried out for 3 minutes under the conditions of 680 rpm for revolution / 511 rpm for rotation to prepare a conductive carbon material dispersion liquid with a solid content concentration of 10 mass%. The conductive carbon material dispersion liquid was mixed with the aqueous dispersion A of the TFE-based polymer obtained in Production Example 1 so that the mass ratio of the TFE-based polymer to the conductive carbon material was 95:5, and further deionized water was added to adjust the solid content concentration (total of the conductive carbon material and the TFE-based polymer) to 10 mass%. The adjusted aqueous dispersion was added to a coagulation tank equipped with a stirring blade and a baffle plate, nitric acid was added as a coagulant, and stirring was carried out to cause coagulation to obtain a wet powder. The obtained wet powder was dried at 210 °C for 18 hours to obtain a TFE-based polymer composition 1. The water content of the obtained TFE-based polymer composition 1 was 0.001% by mass, and the content of (H-(CF2) n -SO3)H (where n is 4 to 20) was less than 10 mass ppb / polymer. The content of (H-(CF2) m-1 -COO)H (where m is 14 to 17) of the TFE-based polymer composition 1 is shown in Table 7.

[0361] Production Example 2 A TFE-based polymer composition 2 was obtained in the same manner as in Production Example 1, except that the mass ratio of the TFE-based polymer to the conductive carbon material was changed to 80:20. The water content of the obtained TFE-based polymer composition 2 was 0.002% by mass, and the content of (H-(CF2) n -SO3)H (where n is 4 to 20) was less than 10 mass ppb / polymer. The content of (H-(CF2) m-1 -COO)H (where m is 14 to 17) of the TFE-based polymer composition 2 is shown in Table 7.

[0362] Production Example 3 A TFE-based polymer composition 3 was obtained in the same manner as in Production Example 1, except that the mass ratio of the TFE-based polymer to the conductive carbon material was changed to 60:40. The water content of the obtained TFE-based polymer composition 3 was 0.002% by mass, and the content of (H-(CF2) n -SO3)H (where n is 4 to 20) was less than 10 mass ppb / polymer. The content of (H-(CF2) m-1 -COO)H (where m is 14 to 17) of the TFE-based polymer composition 3 is shown in Table 7.

[0363] Preparation Example 2 A mixture of 10-undecen-1-ol (16 g), 1,4-benzoquinone (10.2 g), DMF (160 mL), water (16 mL), and PdCl2 (0.34 g) was heated and stirred at 90 °C for 12 hours. 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 solution of sodium methoxide (3.8 g) / methanol (12 mL) was added dropwise to the reaction solution. The precipitated solid was filtered under reduced pressure and washed with ethyl acetate to obtain sodium 10-oxoundecyl sulfate (15.5 g) (hereinafter referred to as surfactant A). 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 replaced 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 cooled to obtain an aqueous surfactant solution B.

[0364] Production Example 2 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 replaced 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 disuccinic 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 a TFE-based polymer aqueous dispersion B. The solid content of the obtained aqueous dispersion B of the TFE-based polymer was 25.9% by mass, and the average primary particle size was 290 nm.

[0365] 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 dried at 210 °C for 18 hours to obtain a TFE-based polymer powder. The standard specific gravity of the obtained TFE-based polymer powder was 2.151, the thermal instability index was 42, the 0.1% by mass reduction temperature was 397 °C, the 1.0% by mass reduction temperature was 492 °C, and the endothermic peak temperature was 344 °C.

[0366] Production Example 4 A TFE-based polymer composition 4 was obtained in the same manner as in Production Example 1, except that the TFE aqueous dispersion prepared in Production Example 2 was used and the mass ratio of the TFE-based polymer to the conductive carbon material was changed to 80:20. The water content of the obtained TFE-based polymer composition 4 was 0.002% by mass, and the content of (H-(CF2)8-SO3)H was 1130 mass ppb. The content of (H-(CF2) m-1 -COO)H (where m is 14 to 17) of the TFE-based polymer composition 4 is shown in Table 7.

[0367] Preparation Example 3 White solid A was obtained by the method described in Synthesis Example 1 of International Publication No. 2021 / 045228.

[0368] Production Example 3 A 6-liter SUS autoclave equipped with a stirring blade and a temperature-regulating 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 autoclave was purged with nitrogen gas to remove oxygen. TFE was injected to set the internal pressure to 0.78 MPaG, and the internal 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 internal pressure decreased, but TFE was added to maintain the internal temperature at 70°C and the internal 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, and after cooling, the paraffin wax was separated to obtain an aqueous dispersion X of a TFE-based polymer. The average primary particle diameter of the obtained aqueous dispersion X of the TFE-based polymer was 310 nm, and the solid content concentration was 25.3 mass%.

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

[0370] Production Example 5 Except for using the TFE aqueous dispersion X prepared in Production Example 3, in the same manner as in Production Example 1, a TFE-based polymer composition X having a composition with a mass ratio of the TFE-based polymer to the conductive carbon material of 95:5 was obtained. The water content of the obtained TFE-based polymer composition X was 0.000 mass%, (H-(CF2) m-1Content of (H-(CF2)-COO)H (where m is from 4 to 20), (H-(CF2) n Content of (H-(CF2)-SO3)H (where n is from 4 to 20) was less than 10 mass ppb.

[0371] Production Example 6 The TFE aqueous dispersion X prepared in Production Example 3 was diluted to a solid content concentration of 13 mass%, stirred and coagulated to obtain a wet powder. The obtained wet powder was dried at 180 °C for 18 hours to obtain a TFE-based polymer composition Y. The water content of the obtained TFE-based polymer composition Y was 0.000 mass%, (H-(CF2) m-1 Content of (H-(CF2)-COO)H (where m is from 4 to 20), (H-(CF2) n Content of (H-(CF2)-SO3)H (where n is from 4 to 20) was less than 10 mass ppb.

[0372] Production Example 7 As the conductive carbon material, a multi-walled carbon nanotube was used in place of carbon black, and a TFE-based polymer composition 5 was obtained in the same manner as in Production Example 1 except that the mass ratio of the TFE-based polymer to the conductive carbon material was changed to 33:67. The water content of the obtained TFE-based polymer composition 5 was 0.002 mass%, (H-(CF2) n Content of (H-(CF2)-SO3)H (where n is from 4 to 20) was less than 10 mass ppb / polymer. The (H-(CF2) m-1 Content of (H-(CF2)-COO)H (where m is from 14 to 17) of the TFE-based polymer composition 5 is shown in Table 7.

[0373]

Table 7

[0374] The composition ratios of the TFE-based polymer compositions obtained in each production example are shown in Table 8.

Table 8

[0375] Each TFE-based polymer composition obtained above was evaluated by the following method.

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

[0377]

Table 9

[0378] Evaluation of the electrode binder sheet for the electrolyte-containing battery The preparation and evaluation of the binder sheets of Examples B1 to B5 and Comparative Examples B1 to B2 were carried out according to the following procedure.

[0379] <Preparation of the positive electrode binder sheet> The active material, conductive carbon material, and binder (TFE-based polymer composition) were weighed and measured into a container. The temperature was sufficiently raised in a constant temperature bath at 50 °C, and immediately put into a high-speed flow mixer to start stirring. By treating at 3000 rpm for 30 minutes, the dispersion of each material and the fibrillation of the TFE-based polymer composition were carried out to obtain a mixture. Then, the mixture was put into a mixer (WDL-1 manufactured by Osaka Chemical Co., Ltd.) and treated for 2 minutes to pulverize the mixture and obtain an electrode binder. The electrode binder was put onto metal rolls arranged parallel to the left and right, and an electrode binder sheet was obtained by rolling while applying a shearing force (left and right roll temperatures: 120 °C, left roll rotation speed: 1 m / min, right roll rotation speed: 0.4 m / min). Table 10 shows each material type and composition.

[0380]

Table 10

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

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

[0383] <Fabrication of the electrolytic solution> As an organic solvent, a mixed solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (EC:EMC = 30:70 (volume ratio)) was measured into a sample bottle, and fluoroethylene carbonate (FEC) and vinylene carbonate (VC) were dissolved therein at 1% by mass each to prepare a mixed solution. To this mixed solution, LiPF6 salt was mixed at 23 °C so that the concentration in the electrolytic solution was 1.1 mol / L to obtain a non-aqueous electrolytic solution.

[0384] <Fabrication of the aluminum laminate cell> The above positive electrode was opposed to the negative electrode via a microporous polyethylene film (separator) with a thickness of 20 μm, the non-aqueous electrolytic solution obtained above was injected, and after the non-aqueous electrolytic solution sufficiently penetrated the separator and the like, it was sealed to fabricate a lithium-ion secondary battery.

[0385] <DC resistance evaluation> The lithium-ion secondary battery manufactured as described above was charged at a constant current to 4.2 V at 25°C with a current corresponding to 0.1C (hereinafter referred to as CC / CV charging) while being sandwiched and pressurized between plates. After cutting at 0.05C, it was discharged at a constant current of 1C to 3V, and this was regarded as one cycle, and charging and discharging were performed up to 3 cycles. Here, 1C represents the current value for discharging the reference capacity of the battery in 1 hour. For example, 0.2C represents a current value that is 1 / 5 of that value. After continuously charging the battery after 3 cycles to a fully charged state, after a 30-minute rest, the voltage drop amount ΔV when discharging at 1C for 5 seconds was used to Ohm's law: R [Ω]=ΔV [V] / 1C current amount [A] calculate the direct current resistance (DC-IR) of the battery. Taking the resistance value of Comparative Example B2 as 100, relative evaluations were made for Examples B1 to B5 and Comparative Example B1. The results are shown in Table 11.

[0386]

Table 11

Claims

1. A tetrafluoroethylene-based polymer composition used as a binder for an electrochemical device, comprising a tetrafluoroethylene-based polymer, at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and a conductive carbon material, wherein the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 10% by mass or more. A tetrafluoroethylene-based polymer composition. 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 from 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. The tetrafluoroethylene-based polymer composition according to claim 1, wherein the tetrafluoroethylene-based polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene consisting only of polymerization units based on tetrafluoroethylene units and hexafluoropropylene.

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

4. The tetrafluoroethylene-based polymer composition according to claim 1 or 2, which is in powder form.

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

6. A binder for an electrochemical device consisting essentially of only a tetrafluoroethylene-based polymer composition, wherein the tetrafluoroethylene-based polymer composition comprises a tetrafluoroethylene-based polymer, at least one compound selected from the group consisting of a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and a conductive carbon material, wherein the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 10% by mass or more. A binder for an electrochemical device. 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 (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 optionally substituted imidazolium, an optionally substituted pyridinium, or an optionally substituted phosphonium. q is 1 or 2.)

7. The binder for an electrochemical device according to claim 6, wherein the amount of the tetrafluoroethylene-based polymer relative to the solid content in the tetrafluoroethylene-based polymer composition is 30% by mass or more.

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

9. The binder for an electrochemical device according to claim 6 or 7, wherein the tetrafluoroethylene-based polymer is polytetrafluoroethylene.

10. The binder for an electrochemical device according to claim 6 or 7, wherein the tetrafluoroethylene-based polymer is at least one selected from the group consisting of a homopolymer of tetrafluoroethylene and a modified polytetrafluoroethylene composed only of a polymerization unit based on a tetrafluoroethylene unit and a hexafluoropropylene unit.

11. The binder for an electrochemical device according to claim 6 or 7, wherein the conductive carbon material is a carbon nanotube.

12. The binder for an electrochemical device according to claim 6 or 7, wherein the amount of the conductive carbon material relative to the solid content in the tetrafluoroethylene-based polymer composition is 1 to 70% by mass.

13. The binder for an electrochemical device according to claim 6 or 7, wherein the tetrafluoroethylene-based polymer composition is substantially free of moisture.

14. The binder for an electrochemical device according to claim 6 or 7, wherein the tetrafluoroethylene-based polymer composition is substantially free of the compound represented by the following general formula (3). General formula (3): (H-(CF ２ )) ８ -SO ３ )) ｑ M ２ (In the formula, M ２ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. q is 1 or 2.)

15. The binder for an electrochemical device according to claim 6 or 7, wherein the tetrafluoroethylene-based polymer composition contains at least one compound selected from the group consisting of the compound represented by the following general formula (4) and the compound represented by the following general formula (4'), and the content of each of them is 1000 mass ppb or less with respect to the tetrafluoroethylene-based polymer composition. General formula (4): (H-(CF ２ )) １５ -COO) ｐ M １ (In the formula, M １ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (4'): (H-(CF ２ )) １６ -COO) ｐ M １ (In the formula, M １ is H, a metal atom, NR ５ ４ (R ５ is the same as described above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.)

16. The binder for an electrochemical device according to claim 6 or 7, wherein the tetrafluoroethylene-based polymer composition contains at least one compound selected from the group consisting of the compound represented by the following general formula (5) and the compound represented by the following general formula (5'), and the content of each of them is 1000 mass ppb or less with respect to the tetrafluoroethylene-based polymer composition. General formula (5): (H-(CF ２ )) １３ -COO) ｐ M １ (In the formula, M １ is H, a metal atom, NR ５ ４ (R ５ may be the same or different and is H or an organic group having 1 to 10 carbon atoms), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.) General formula (5'): (H-(CF ２ )) １４ -COO) ｐ M １ (In the formula, M １ is H, a metal atom, NR ５ ４ (R ５ is the same as described above), imidazolium which may have a substituent, pyridinium which may have a substituent, or phosphonium which may have a substituent. p is 1 or 2.)

17. The binder for an electrochemical device according to claim 6 or 7, wherein the thermal instability index (TII) of the tetrafluoroethylene-based polymer composition is 5 or more.

18. The binder for an electrochemical device according to claim 6 or 7, which is a powder.

19. The binder for an electrochemical device according to claim 6 or 7, which is for a lithium-ion secondary battery.

20. An electrode mixture containing the tetrafluoroethylene-based polymer composition according to claim 1 or 2, or the binder for an electrochemical device according to claim 6 or 7, and an electrode active material.

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

22. An electrode containing the tetrafluoroethylene-based polymer composition according to claim 1 or 2, or the binder for an electrochemical device according to claim 6 or 7, an electrode active material, and a current collector.

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

Images