Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F216/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical
  • C08F216/38—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical by an acetal or ketal radical
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
  • H01M4/623—Binders being polymers fluorinated polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/28—Condensation with aldehydes or ketones
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L29/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal or ketal radical; Compositions of hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Compositions of derivatives of such polymers
  • C08L29/14—Homopolymers or copolymers of acetals or ketals obtained by polymerisation of unsaturated acetals or ketals or by after-treatment of polymers of unsaturated alcohols
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D129/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Coating compositions based on hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Coating compositions based on derivatives of such polymers
  • C09D129/14—Homopolymers or copolymers of acetals or ketals obtained by polymerisation of unsaturated acetals or ketals or by after-treatment of polymers of unsaturated alcohols
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
  • C08K2003/2203—Oxides; Hydroxides of metals of lithium
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
  • C08K2003/2289—Oxides; Hydroxides of metals of cobalt
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a resin composition for a secondary battery electrode which is excellent in active material dispersibility, electrolytic solution resistance, and coating film density, and which is capable of achieving both high conductivity and adhesiveness.
• a polyvinyl acetal resin is a resin synthesized using polyvinyl alcohol as a raw material, and has an acetyl group, a hydroxyl group, and an acetal group in side chains. Thereby, excellent toughness, adhesiveness, and the like can be exhibited. Also, by changing the ratio of the side chain groups, it is possible to change the physical properties of the resin. Taking advantage of such properties, polyvinyl acetal resins are used in applications such as electrodes for storage batteries, pigment compositions, and ceramic green sheets.
• Patent Document 1 describes the use of a polyvinyl acetal resin containing an aromatic acetal group in a composition for a lithium secondary battery electrode.
• Patent Document 1 when the polyvinyl acetal resin disclosed in Patent Document 1 is used as an electrode material for a secondary battery, there is a problem that the dispersibility of the active material, the electrolyte resistance, and the coating film density are lowered. In addition, it is not possible to achieve both conductivity and adhesion. If the conductivity is increased, the structure becomes rigid and adhesion decreases, and if the adhesion is increased, an electronic conduction path is not formed and the battery performance decreases There is a problem that Accordingly, there is a demand for a resin that is excellent in dispersibility of an active material, resistance to an electrolyte solution, and coating film density, and exhibits excellent adhesiveness while maintaining high conductivity.
• An object of the present invention is to provide a resin composition for a secondary battery electrode that is excellent in dispersibility of an active material, electrolyte resistance, and coating film density, and is capable of achieving both high conductivity and adhesiveness.
• the present invention comprises an active material, a non-aqueous solvent, and a polyvinyl acetal resin, wherein the polyvinyl acetal resin has a structural unit having a halogen atom and has a Vicat softening temperature of 50° C. or higher and 150° C. or lower. It is a resin composition for a secondary battery electrode.
• the present invention will be described in detail below.
• the present inventors have found that by using a combination of an active material, a non-aqueous solvent, and a polyvinyl acetal resin having a specific structure and physical properties, the dispersibility of the active material, the electrolyte resistance, and the coating density It has been found that both high electrical conductivity and adhesiveness can be achieved. Further, the inventors have found that a secondary battery obtained by using such a resin composition for a secondary battery electrode can achieve a high capacity retention rate, and have completed the present invention.
• the resin composition for secondary battery electrodes of the present invention contains an active material.
• the active material include a positive electrode active material and a negative electrode active material.
• the positive electrode active material include lithium-containing composite metal oxides such as lithium nickel oxide, lithium cobalt oxide, and lithium manganese oxide. Specific examples include LiNiO 2 , LiCoO 2 , LiMn 2 O 4 and the like.
• the negative electrode active material for example, materials conventionally used as negative electrode active materials for storage batteries can be used, for example, spherical natural graphite, natural graphite, artificial graphite, amorphous carbon, carbon black, or Examples include those obtained by adding different elements to these components. In addition, these may be used independently and may use 2 or more types together.
• the resin composition for a secondary battery electrode of the present invention further contains a conductive aid (conductive imparting agent).
• a conductive aid conductive imparting agent
• the electrical resistance of the obtained composition for storage battery electrodes can be further reduced.
• the conductive aid include carbon materials such as graphite, acetylene black, carbon black, ketjen black, and vapor-grown carbon fiber.
• the content of the active material in the resin composition for a secondary battery electrode of the present invention is preferably 20% by weight or more, more preferably 25% by weight or more, and further preferably 30% by weight or more. More preferably, it is 80% by weight or less, and more preferably 70% by weight or less.
• the resin composition for secondary battery electrodes of the present invention contains a non-aqueous solvent.
• the non-aqueous solvent means a solvent having a water content of 100 mass ppm or less in terms of mass.
• the non-aqueous solvent include organic solvents such as ketones, alcohols, aromatic hydrocarbons, esters and amides.
• ketones include acetone, methyl ethyl ketone, dipropyl ketone and diisobutyl ketone.
• Examples of alcohols include methanol, ethanol, isopropanol, and butanol. Toluene, xylene, etc. are mentioned as said aromatic hydrocarbons.
• esters examples include methyl propionate, ethyl propionate, butyl propionate, methyl butanoate, ethyl butanoate, butyl butanoate, methyl pentanoate, ethyl pentanoate, butyl pentanoate, methyl hexanoate, ethyl hexanoate, butyl hexanoate, 2-ethylhexyl acetate, 2-ethylhexyl butyrate and the like.
• methyl cellosolve, ethyl cellosolve, butyl cellosolve, terpineol, dihydroterpineol, butyl cellosolve acetate, butyl carbitol acetate, terpineol acetate, dihydroterpineol acetate and the like can also be used.
• the carbonates include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate and the like.
• the amides include dimethylacetamide, N,N-dimethylformamide, 1-methyl-2-pyrrolidone (N-methylpyrrolidone), diethylformamide and the like.
• amides are preferred, and compounds having a lactam structure are particularly preferred.
• the compound having a lactam structure a compound containing a 3- to 6-membered ring lactam structure is preferable, and a compound containing a 5-membered ring lactam structure is particularly preferable.
• the content of the non-aqueous solvent in the resin composition for a secondary battery electrode of the present invention is preferably 5% by weight or more, more preferably 10% by weight or more, and 45% by weight or less. Preferably, it is 40% by weight or less.
• the resin composition for secondary battery electrodes of the present invention contains a polyvinyl acetal resin.
• the polyvinyl acetal resin has a structural unit having a halogen atom, and has a Vicat softening temperature of 50° C. or higher and 150° C. or lower.
• the dispersibility of the active material can be sufficiently improved, and both high conductivity and dispersibility of the active material can be achieved.
• the polyvinyl acetal resin has a Vicat softening temperature of 50°C or higher and 150°C or lower.
• a Vicat softening temperature is within the above range, excellent electrolyte resistance and high electrical conductivity can be achieved. In addition, changes in coating film density are suppressed, making it possible to produce a dense electrode sheet.
• a preferable lower limit of the Vicat softening temperature is 60°C, a more preferable lower limit is 70°C, a preferable upper limit is 100°C, and a further preferable upper limit is 90°C.
• the Vicat softening temperature can be measured by a method conforming to JIS K 7206:2016 (Plastics-Thermoplastics-Determination of Vicat softening temperature (VST) A50 method).
• the Vicat softening temperature is determined by the structure of the polyvinyl acetal resin (in particular, the structure of the structural unit having a halogen atom), the following numerical range of the polyvinyl acetal resin (the numerical range related to the structural unit having a halogen atom, the amount of hydroxyl groups , acetyl group content, degree of polymerization, etc.) can be adjusted by the method for producing the polyvinyl acetal resin.
• the polyvinyl acetal resin contains a structural unit having a halogen atom.
• a structural unit having the halogen atom By containing the structural unit having the halogen atom, excellent adhesiveness and dispersibility can be obtained. Moreover, when it is used as an electrode, the electrode resistance can be lowered, and deterioration due to the electrolytic solution can be prevented, making it possible to produce a high-output storage battery.
• halogenation-modified unit amount means the content of structural units having a halogen atom.
• halogenation-modified acetal bond unit amount means the content of a structure in which halogen atoms are bonded via acetal bonds (halogenation-modified acetal bond units).
• non-halogenated acetal group amount means the content of structural units having an acetal group, excluding the halogenated modified acetal bond units.
• “Acetal group content” means the content of structural units having an acetal group. That is, it also includes a halogenated modified acetal linking unit.
• the halogen atom is preferably at least one selected from the group consisting of fluorine, chlorine and bromine. Among them, it is more preferable to use chlorine.
• the structural unit having a halogen atom preferably has 1 to 3 halogen atoms.
• the structural unit having a halogen atom is not particularly limited as long as it has a structure having a halogen atom. etc. are preferred.
• the structure in which halogen atoms are bonded via an acetal bond also includes the case of further bonding via a linking group other than an acetal bond.
• the halogen atom is fluorine, it is preferably used in combination with an aromatic hydrocarbon, and when the halogen atom is chlorine, it is preferably used in combination with an aliphatic hydrocarbon.
• the structural unit having a halogen atom has a structure in which the halogen atom is bonded via an acetal bond (hereinafter, such a structural unit is also referred to as a halogenated modified acetal bond unit), it is represented by the following formula (1).
• the structure which has a multiple types of halogen atom in one structural unit may be sufficient. Further, it may have a structure having a plurality of constitutional units having different halogen atom species.
• R6 represents a halogen atom-containing hydrocarbon group.
• the halogenated modified acetal bond unit is preferably a structural unit represented by the following formula (2).
• R 1 represents a halogen atom or a halogenated alkyl group
• R 2 and R 3 each independently represent a hydrogen atom or a halogen atom.
• R 2 and R 3 may be halogenated alkyl groups.
• halogenated alkyl group examples include a chloroalkyl group, a fluoroalkyl group and a bromoalkyl group.
• chloroalkyl group examples include a chloromethyl group (--CH 2 Cl), a chloroethyl group (--CH 2 CH 2 Cl), a dichloroethyl group, a chloropropyl group and a trichloromethyl group.
• R 1 is preferably a chlorine atom, -CH 2 Cl or -CH 2 CH 2 Cl.
• fluoroalkyl group examples include a fluoromethyl group (--CH 2 F), a fluoroethyl group (--CH 2 CH 2 F), a difluoroethyl group, a fluoropropyl group, a trifluoromethyl group and the like.
• bromoalkyl group examples include a bromomethyl group (--CH 2 Br), a bromoethyl group (--CH 2 CH 2 Br), a dibromoethyl group, a bromopropyl group, a tribromomethyl group and the like.
• the above R 6 can be a halogen atom-containing aromatic group.
• the halogen atom of the halogen atom-containing aromatic group is preferably chlorine, fluorine or bromine.
• the halogen atom-containing aromatic group include a chlorophenyl group, a chloroalkylphenyl group, a fluorophenyl group, a fluoroalkylphenyl group, a bromophenyl group, and a bromoalkylphenyl group.
• the chlorophenyl group include 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2,4-dichlorophenyl group and 3,4-dichlorophenyl group.
• chloroalkylphenyl group examples include 2-chloromethylphenyl group, 3-chloromethylphenyl group and 4-chloromethylphenyl group.
• the chlorophenyl group and chloroalkylphenyl group may have other substituents in addition to the chloro group.
• Examples of the fluorophenyl group include 2-fluorophenyl group, 3-fluorophenyl group, 4-fluorophenyl group, 2,4,6-trifluorophenyl group and perfluorophenyl group.
• the fluoroalkylphenyl group includes a 4-trifluoromethylphenyl group, a 3-trifluoromethylphenyl group, a 3,5-ditrifluoromethylphenyl group, a 4-pentafluoroethylphenyl group and a 4-perfluorohexylphenyl group. and the like.
• the bromophenyl group include a 2-bromophenyl group and a 3-bromophenyl group.
• the structural unit having a halogen atom has a structure having a halogen atom or a halogen atom-containing group in a side chain (hereinafter, such a structural unit is also referred to as a halogenated modified side chain binding unit), the following formula (3) It is preferably a structural unit represented by By having a structural unit represented by the following formula (3), the modified polyvinyl acetal resin has excellent adhesiveness and dispersibility, and the obtained composition has even better stability over time. Moreover, when it is used for the electrode of a storage battery, the electrode resistance can be reduced.
• R4 represents a single bond or an alkylene group
• R5 represents a hydrogen atom, a halogen atom or a halogenated alkyl group
• X represents at least one selected from the group consisting of fluorine, chlorine and bromine. show.
• R 4 may be a halogenated alkylene group.
• the alkylene group represented by R 4 above preferably has 1 to 20 carbon atoms, such as a linear alkylene group, a branched alkylene group, and a cyclic alkylene group.
• Examples of the linear alkylene group include methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, octamethylene group and decamethylene group.
• Examples of the branched alkylene group include a methylmethylene group, a methylethylene group, a 1-methylpentylene group and a 1,4-dimethylbutylene group.
• cyclic alkylene group examples include a cyclopropylene group, a cyclobutylene group, and a cyclohexylene group.
• linear alkyl groups such as methylene group, ethylene group, n-propylene group and n-butylene group are preferred, and methylene group and ethylene group are more preferred.
• chloroalkyl group represented by R 5 above the same groups as those for R 1 can be used. Further, in the present invention, it is preferable to use a combination of a single bond for R4 and a hydrogen atom for R5 .
• the preferable lower limit of the content of the structural unit having a halogen atom (halogenation-modified unit amount) relative to the total structural units of the polyvinyl acetal resin is 0.01 mol %, and the preferred upper limit is 20 mol %. Adhesiveness and dispersibility can be improved by adjusting the amount of the halogenated modified unit to 0.01 mol % or more.
• the more preferable lower limit of the amount of the halogenated modification unit is 0.05 mol%, the more preferable lower limit is 0.1 mol%, the more preferable upper limit is 15 mol%, and the more preferable upper limit is 10 mol%.
• the amount of the halogenated modified unit means the sum of both. Further, when the polyvinyl acetal resin has two kinds of structural units having halogen atoms, the ratio of the amounts of the two kinds of halogenated modified units is preferably in the range of 100:1 to 1:100.
• the content of the halogenated modified acetal bond units (halogenated modified acetal bond unit amount)
• a preferable lower limit is 0.01 mol%, and a preferable upper limit is 20 mol%. Adhesiveness and dispersibility can be improved by adjusting the amount of the halogenated modified acetal bond unit to 0.01 mol % or more.
• the more preferable lower limit of the amount of the halogenated modification unit is 0.05 mol%, the more preferable lower limit is 0.1 mol%, the more preferable upper limit is 15 mol%, and the more preferable upper limit is 10 mol%.
• the more preferable lower limit of the content of the halogenation-modified side-chain-bonding unit is 0. .1 mol %, and a more preferred upper limit is 15 mol %.
• a more preferable lower limit is 0.5 mol%, and a more preferable upper limit is 10 mol%. Adhesiveness and dispersibility can be improved by setting it in the said range.
• the ratio of the two (halogenated modified acetal bond units/halogenated modified side chain bond units) is 0. .1 or more and 3 or less, and more preferably 0.5 or more and 2 or less.
• the polyvinyl acetal resin includes a structural unit having an acetal group represented by the following formula (4-1), a structural unit having a hydroxyl group represented by the following formula (4-2), and a structural unit having a hydroxyl group represented by the following formula (4-3). It is preferable to have a structural unit having an acetyl group represented by.
• R 26 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms.
• R 26 is an alkyl group having 1 to 20 carbon atoms
• examples of the alkyl group include methyl group, ethyl group, n-propyl group, isopropyl group and n-butyl group.
• the content of the structural unit having an acetal group represented by the formula (4-1) (hereinafter also referred to as "non-halogenated acetal group content”) is 5.0 mol% or more. preferably 70.0 mol % or less. Within the above range, the dispersibility of the active material can be further improved.
• the amount of non-halogenated acetal groups is more preferably 10.0 mol % or more, and more preferably 60.0 mol % or less.
• the two acetalized groups A method of counting hydroxyl groups is adopted to calculate the amount of acetal groups.
• the amount of non-halogenated acetal groups can be measured, for example, by NMR. Also.
• the content of the aforementioned "structure in which halogen atoms are bonded via acetal bonds" is not included in the amount of non-halogenated acetal groups.
• the content of acetoacetal groups acetalized with acetaldehyde in the polyvinyl acetal resin is preferably 10 mol % or more and 30 mol % or less.
• the content of butyl acetal groups acetalized with butyraldehyde (butyral group content) in the polyvinyl acetal resin is preferably 10 mol % or more and 60 mol % or less.
• the polyvinyl acetal resin contains both a structural unit having a non-halogenated acetal group and a halogenated modified acetal bond unit, it is the total amount of the non-halogenated acetal group amount and the halogenated modified acetal bond unit amount.
• the amount of acetal groups [the amount of non-halogenated acetal groups + the amount of halogenated modified acetal bond units] is preferably 10 mol % or more and 70 mol % or less. By setting it within the above range, the adhesiveness and dispersibility are excellent while maintaining the solubility in the organic solvent. More preferably, the acetal group content is 15 mol % or more and 60 mol % or less.
• the content of the halogenated modified acetal bond unit with respect to the structural unit having the non-halogenated acetal group is 6000 or less. preferable. Moreover, it is more preferable that the ratio is 4000 or less. Although the lower limit is not particularly limited, 1 or more is preferable.
• the total amount of the non-halogenated acetal group amount and the halogenated modified unit amount in the polyvinyl acetal resin is 10 mol% or more and 70 mol% or less. is preferred. Within the above range, the adhesiveness and dispersibility are improved. More preferably, the above non-halogenated acetal group amount+halogenated modification unit amount is 15 mol % or more and 60 mol % or less.
• the ratio of the non-halogenated acetal group amount to the halogenated modified unit amount in the polyvinyl acetal resin is preferably 1 or more and 6000 or less. Within the above range, the adhesiveness and dispersibility are improved. More preferably, the ratio of non-halogenated acetal group/halogenated modified unit is 2 or more and 5000 or less.
• the content of the structural unit having a hydroxyl group represented by the formula (4-2) (hereinafter also referred to as "hydroxyl group content”) is 20 mol% or more and 90 mol% or less. is preferred. By setting it as the said range, while being able to fully improve the dispersibility of an active material, high electronic conductivity can be exhibited.
• the amount of hydroxyl groups is more preferably 30.0 mol % or more, and more preferably 85.0 mol % or less.
• the amount of hydroxyl groups can be measured, for example, by NMR.
• the content of the structural unit having an acetyl group represented by the formula (4-3) (hereinafter also referred to as "acetyl group content”) is preferably 0.1 mol% or more. , is more preferably 5.0 mol % or more, preferably 20.0 mol % or less, and more preferably 15.0 mol % or less.
• acetyl group content is preferably 0.1 mol% or more.
• the amount of acetyl groups can be measured, for example, by NMR.
• the average degree of polymerization of the polyvinyl acetal resin is preferably 100 or more and 6000 or less. Within the above range, the dispersibility of the active material can be sufficiently improved, and high conductivity can be exhibited.
• the average degree of polymerization is preferably 150 or more and 5500 or less, more preferably 200 or more and 4000 or less.
• the average degree of polymerization can be measured, for example, according to JIS K6726-1994.
• the "average degree of polymerization of polyvinyl acetal resin" means the average degree of polymerization of polyvinyl alcohol resin as a raw material.
• the content of the polyvinyl acetal resin in the resin composition for a secondary battery electrode of the present invention is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, and 20.0% by weight. % or less, more preferably 15.0% by weight or less.
• the ratio of the content of the polyvinyl acetal resin to the content of the active material (polyvinyl acetal resin content/active material content) in the resin composition for a secondary battery electrode of the present invention is 0.01 or more. preferably 10.0 or less. Within the above range, the dispersibility of the active material is improved, making it easier to form a conductive path. As a result, the conductivity becomes even more excellent.
• the content ratio is more preferably 0.10 or more, and more preferably 8.00 or less.
• a method for producing the polyvinyl acetal resin a method of preparing a polyvinyl alcohol containing a structural unit having a halogen atom and then acetalizing it, a method of acetalizing a polyvinyl alcohol containing no structural unit having a halogen atom, and then a halogen atom and the like. Further, a method of preparing a polyvinyl alcohol containing a structural unit having a halogen atom or a polyvinyl alcohol not containing a structural unit having a halogen atom and then introducing a structural unit having a halogen atom by acetalization can be used.
• polyvinyl alcohol having a structural unit represented by the above formula (3) is prepared in advance and then acetalized. and adding moieties corresponding to R 4 and R 5 of the structural unit represented by the above formula (3).
• a polyvinyl alcohol previously having a structural unit represented by the above formula (3) and a polyvinyl alcohol not having a structural unit represented by the above formula (3) are prepared, and then acetalized to form a poly(vinyl alcohol) represented by the above formula (3). and a method of introducing a structural unit to be used.
• polyvinyl alcohol containing a structural unit having a halogen atom for example, vinyl chloride and vinyl acetate are copolymerized, and then acid or alkali is added to an alcohol solution of the obtained copolymer to obtain a poly(vinyl alcohol). and the like.
• Polyvinyl alcohol containing a structural unit having the above halogen atom may also be produced by a method of adding a halogen atom. Examples of the method for adding the halogen atom include a method of reacting polyvinyl alcohol with a halogen gas.
• Polyvinyl alcohol containing no structural unit having a halogen atom (hereinafter also simply referred to as polyvinyl alcohol) can be obtained, for example, by saponifying a copolymer of vinyl ester and ethylene.
• the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, and vinyl pivalate. Among them, vinyl acetate is preferable from the viewpoint of economy.
• aldehydes having a halogen atom include, for example, chloroacetaldehyde, dichloroacetaldehyde, trichloroacetaldehyde, 3-chloropropionaldehyde, 4-chlorobutyraldehyde and the like.
• examples of the aldehyde having a fluorine atom include a fluorine atom-containing aliphatic aldehyde and a fluorine atom-containing aromatic aldehyde.
• examples of the fluorine atom-containing aliphatic aldehyde include fluoroacetaldehyde, difluoroacetaldehyde, trifluoroacetaldehyde, 2,2,3,3,3-pentafluoropropionaldehyde, 3-fluoropropionaldehyde, and 3,3,3-trifluoropropione. aldehyde, 4-fluorobutyraldehyde and the like.
• fluorine atom-containing aromatic aldehyde examples include fluorobenzaldehyde, fluoromethylbenzaldehyde, difluoromethylbenzaldehyde, trifluoromethylbenzaldehyde, 3-(4-fluorophenyl)propionaldehyde and the like.
• aldehydes having a halogen atom examples of the aldehyde having a bromine atom include bromine atom-containing aliphatic aldehydes and bromine atom-containing aromatic aldehydes. Acetyl bromide etc. are mentioned as said fluorine atom containing aliphatic aldehyde.
• fluorine atom-containing aromatic aldehyde examples include 4-bromonicotinaldehyde, 2-bromoisophthalaldehyde, 1-bromo-2-naphthaldehyde, 4-bromo-2-thiophenecarboxaldehyde, 4-bromobenzaldehyde, and 3-bromosalicyl. aldehyde, 4-bromo-1-naphthaldehyde, 5-bromo-2-pyridinecarboxaldehyde and the like.
• the aldehyde equivalent is an aldehyde with a protecting group or a compound that can be converted into an aldehyde by a commonly used method, and examples thereof include acetal, hemiacetal, and aldehyde hydrate. Among them, an aldehyde equivalent having a halogen atom is preferable.
• the aldehyde equivalents having a chlorine atom include chloroacetaldehyde dimethyl acetal, chloroacetaldehyde diethyl acetal, 2-chloromethyl-1,3-dioxolane, dichloroacetaldehyde dimethyl acetal, and dichloroacetaldehyde diethyl.
• aldehyde equivalents having a fluorine atom include difluoroacetaldehyde ethyl hemiacetal, 2-(perfluorohexyl)acetaldehyde dimethyl acetal, fluoroacetaldehyde dimethyl acetal, fluoroacetaldehyde diethyl acetal, 2- fluoromethyl-1,3-dioxolane, 2-(perfluorohexyl)acetaldehyde dimethyl acetal, difluoroacetaldehyde dimethyl acetal, difluoroacetaldehyde diethyl acetal, trifluoroacetaldehyde dimethyl acetal, trifluoroacetaldehyde diethyl acetal, trifluoroacetaldehyde methyl hemiacetal, tri fluoroacetaldehyde ethyl hemiacetal, tri fluoroacetaldehyde ethyl
• aldehyde equivalents having a halogen atom examples include bromoacetaldehyde diethyl acetal, 3-bromobenzaldehyde diethyl acetal, and 4-bromobenzaldehyde diethyl acetal.
• the polyvinyl acetal resin may be one obtained by copolymerizing an ethylenically unsaturated monomer as long as the effects of the present invention are not impaired.
• the ethylenically unsaturated monomer is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, and (anhydrous) itaconic acid. Also included are acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride, acrylamido-2-methylpropanesulfonic acid and sodium salts thereof.
• Terminal-modified polyvinyl alcohol obtained by copolymerizing a vinyl ester monomer such as vinyl acetate and ethylene in the presence of a thiol compound such as thiolacetic acid or mercaptopropionic acid and saponifying the copolymer may also be used. can be done.
• the polyvinyl alcohol which is the raw material of the polyvinyl acetal resin, preferably has a saponification degree of 80.0 mol% or more and 99.9 mol% or less, and preferably 85.0 mol% or more and 95.0 mol% or less. more preferred.
• the dispersibility of the active material can be further enhanced.
• a known method can be used for the acetalization, and it is preferably carried out in an aqueous solvent, in a mixed solvent of water and an organic solvent having compatibility with water, or in an organic solvent.
• an organic solvent compatible with water for example, an alcohol-based organic solvent can be used.
• the organic solvent include alcohol-based organic solvents, aromatic organic solvents, aliphatic ester-based solvents, ketone-based solvents, lower paraffin-based solvents, ether-based solvents, amide-based solvents, and amine-based solvents.
• the acetalization is preferably carried out in the presence of an acid catalyst.
• the acid catalyst is not particularly limited, and includes mineral acids such as sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid, carboxylic acids such as formic acid, acetic acid and propionic acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid and paratoluenesulfone. sulfonic acids such as acids.
• These acid catalysts may be used alone or in combination of two or more compounds. Among them, hydrochloric acid, nitric acid and sulfuric acid are preferred, and hydrochloric acid is particularly preferred.
• Aldehydes that are commonly used for acetalization include aldehydes having a chain aliphatic group, a cycloaliphatic group, or an aromatic group having 1 to 10 carbon atoms. Conventionally known aldehydes can be used as these aldehydes.
• the aldehyde used in the acetalization reaction is not particularly limited, and examples thereof include aliphatic aldehydes and aromatic aldehydes.
• Examples of the aliphatic aldehyde include formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, n-hexylaldehyde, 2-ethylbutyraldehyde, 2-ethylhexylaldehyde, n-heptylaldehyde, n- octylaldehyde, octeraldehyde, n-nonylaldehyde, n-decylaldehyde, amylaldehyde and the like.
• aromatic aldehyde examples include aromatic aldehydes such as benzaldehyde, cinnamaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde and ⁇ -phenylpropionaldehyde. etc.
• cyclic multimers such as paraldehyde and metaldehyde can be used. These aldehydes may be used individually by 1 type, and may use 2 or more types together.
• aldehydes formaldehyde, acetaldehyde, butyraldehyde, 2-ethylhexylaldehyde, 2-ethylhexylaldehyde, etc., which are excellent in acetalization reactivity, bring about a sufficient internal plasticizing effect on the resin to be produced, and as a result impart good flexibility.
• n-nonylaldehyde and paraldehyde are preferred.
• the amount of the aldehyde to be added can be appropriately set according to the amount of acetal groups in the desired polyvinyl acetal resin.
• 10 to 80 mol %, preferably 15 to 75 mol %, relative to 100 mol % of polyvinyl alcohol is preferable because the acetalization reaction is efficiently carried out and unreacted aldehyde is easily removed.
• the resin composition for secondary battery electrodes of the present invention may further contain other binders such as polyvinylidene fluoride, flame retardant aids, antifoaming agents, leveling agents, and adhesion imparting agents within a range that does not impair the effects of the present invention. It may contain additives such as
• the method for producing the resin composition for a secondary battery electrode of the present invention is not particularly limited, and for example, a method of adding a polyvinyl acetal resin obtained by acetalizing raw material polyvinyl alcohol and an active material to a non-aqueous solvent and mixing them. etc.
• Examples of the mixing method include a method using various mixers such as a ball mill, blender mill, and three rolls.
• a secondary battery electrode is formed by, for example, applying the composition for a secondary battery electrode of the present invention onto a conductive substrate and passing through a step of drying.
• various coating methods such as an extrusion coater, a reverse roller, a doctor blade, and an applicator can be employed.
• a resin composition for a secondary battery electrode which is excellent in dispersibility of an active material, resistance to an electrolyte solution, and coating film density, and which is capable of achieving both high conductivity and adhesiveness. can be done.
• the powder of chlorinated modified polyvinyl acetal resin A1 containing a structural unit having a chlorine atom was obtained through neutralization, washing with water and drying by a conventional method. rice field.
• the resulting chlorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), the amount of chlorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• the resulting chlorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), the amount of chlorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• the resulting chlorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), the amount of chlorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• the resulting brominated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectroscopy) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), brominated modified acetal bond unit amount (modified amount), and acetal group amount were measured.
• Table 1 shows the results.
• the resulting chlorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), the amount of chlorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• the resulting chlorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), the amount of chlorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• the resulting brominated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectroscopy) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), brominated modified acetal bond unit amount (modified amount), and acetal group amount were measured.
• Table 1 shows the results.
• the resulting chlorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), the amount of chlorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• chlorination and bromination modified polyvinyl acetal containing structural units having chlorine and bromine atoms A powder of resin A9 was obtained.
• the obtained chlorinated and brominated modified polyvinyl acetal resin was dissolved in DMSO - d 6 (dimethyl sulfoxide), and the amount of hydroxyl groups, acetyl groups and butyral groups (non- Halogenated acetal group amount), chlorinated modified acetal bond unit amount (chlorine modified amount), brominated modified acetal bond unit amount (bromine modified amount), and acetal group amount were measured.
• Table 1 shows the results.
• the resulting fluorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal group amount), the amount of fluorinated modified side chain bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• Table 1 shows the results.
• the resulting chlorinated or fluorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non- Halogenated acetal group amount), chlorinated modified side chain bond unit amount (chlorine modified amount), fluorinated modified side chain bond unit amount (fluorine modified amount), and acetal group amount were measured. Table 1 shows the results.
• the resulting fluorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal group amount), the amount of fluorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• the resulting fluorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal group amount), the amount of fluorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• the resulting chlorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), the amount of chlorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Table 1 shows the results.
• the resulting brominated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectroscopy) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal base amount), brominated modified side chain bond unit amount (modified amount), and acetal group amount were measured.
• Table 1 shows the results.
• the resulting chlorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectroscopy) was used to determine the amount of hydroxyl groups, acetyl groups, acetoacetal groups, and butyral groups. (non-halogenated acetal group amount), chlorinated modified acetal bond unit amount (modified amount), and acetal group amount were measured. Table 1 shows the results.
• the resulting fluorination-modified and chlorination-modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups ( Non-halogenated acetal group amount), fluorinated modified acetal bond unit amount (modified amount), chlorinated modified acetal bond unit amount (modified amount), and acetal group amount were measured.
• polyvinyl acetal resin B1 A polyvinyl acetal resin is dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) is used to determine the amount of hydroxyl groups, the amount of acetyl groups, the amount of butyral groups (the amount of non-halogenated acetal groups), and Acetal group content was measured. Table 1 shows the results.
• the liquid temperature is kept at 50° C. for 6 hours to complete the reaction, and the ethylene oxide-modified and chlorinated-modified polyvinyl acetal resin B2 containing a structural unit having a chlorine atom is neutralized, washed with water and dried by a conventional method. powder was obtained.
• the obtained ethylene oxide-modified and chlorinated-modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide).
• the resulting fluorinated modified polyvinyl acetal resin was dissolved in DMSO-d 6 (dimethyl sulfoxide), and 1 H-NMR (nuclear magnetic resonance spectrum) was used to determine the amount of hydroxyl groups, acetyl groups, and butyral groups (non-halogenated acetal group amount), the amount of fluorinated modified acetal bond units (modified amount), and the amount of acetal group were measured.
• Example 1 To 20 parts by weight of a resin solution containing the obtained polyvinyl acetal resin A1 (polyvinyl acetal resin: 2.5 parts by weight, solvent: N-methylpyrrolidone), lithium cobaltate (manufactured by Nippon Kagaku Kogyo Co., Ltd., Cellseed C -5H) 50 parts by weight, 5 parts by weight of acetylene black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductivity imparting agent, and 25 parts by weight of N-methylpyrrolidone were added. After that, they were mixed with an Awatori Mixer manufactured by THINKY Co., Ltd. to obtain a composition for a secondary battery electrode.
• an Awatori Mixer manufactured by THINKY Co., Ltd. To 20 parts by weight of a resin solution containing the obtained polyvinyl acetal resin A1 (polyvinyl acetal resin: 2.5 parts by weight, solvent: N-methylpyr
• Examples 2 to 18, Comparative Examples 1 to 3 A secondary battery electrode composition was obtained in the same manner as in Example 1, except that the type of polyvinyl acetal resin, the amount of resin added, and the active material were changed as shown in Table 2.
• Example 4 A secondary battery electrode composition was obtained in the same manner as in Example 1, except that PVDF (polyvinylidene fluoride) was used instead of the obtained polyvinyl acetal resin.
• PVDF polyvinylidene fluoride
• Example 5 A secondary battery electrode composition was obtained in the same manner as in Example 1, except that PVC (polyvinyl chloride) was used instead of the obtained polyvinyl acetal resin. ⁇ Evaluation> The polyvinyl acetal resins and compositions for secondary battery electrodes obtained in Examples and Comparative Examples were evaluated as follows. Table 1 shows the results.
• the Vicat softening temperature of the polyvinyl acetal resin was measured according to JIS K 7206:2016 (Plastics-Thermoplastics-Determination of Vicat softening temperature (VST) A50 method). Specifically, the resin powder was press-molded and cut into a width of about 15 mm square to obtain a sheet measurement sample having a thickness of 2 mm. Moreover, the measurement was performed by stacking two measurement samples.
• an HDT tester (3M-2 type, manufactured by Toyo Seiki Co., Ltd.) was used, and the measurement conditions were JIS K7206: 2016 test method A50 method (test load: 10 N, temperature increase rate: 50 ° C./ h), the test starting temperature was 30° C., and the maximum penetration amount was 1 mm.
• the obtained resin composition was coated on a release-treated polyethylene terephthalate (PET) film so that the film thickness after drying was 20 ⁇ m, dried, and peeled from the PET film to prepare a sheet.
• PET polyethylene terephthalate
• the obtained sheet was measured for average surface roughness Rz based on JIS B 0601 (1994).
• Electrolyte resistance (solvent solubility) (Preparation of electrode sheet)
• PET polyalkylene terephthalate
• the secondary battery electrode composition obtained in Examples and Comparative Examples is applied so that the film thickness after drying is 20 ⁇ m, and dried to form an electrode.
• a sheet was produced. The electrode sheet was cut into 2 cm squares to prepare electrode sheet test pieces.
• the secondary battery electrode composition obtained on a conductive release-treated polyethylene terephthalate (PET) film is coated so that the film thickness after drying is 20 ⁇ m, dried and removed from the PET film. A sheet was produced by peeling.
• the electrode resistance value of the obtained sheet was measured using an electrode resistance measuring device (manufactured by Hioki Electric Co., Ltd.) and evaluated according to the following criteria.
• ⁇ The electrode resistance value was less than 500 ⁇ /sq.
• ⁇ The electrode resistance value was 500 ⁇ /sq or more and less than 1000 ⁇ /sq.
• x The electrode resistance value was 1000 ⁇ /sq or more. When the surface resistance value is low, it can be said that the electron conductivity is excellent.
• Battery performance evaluation (capacity retention rate) (Production of coin-type battery)
• the secondary battery electrode compositions obtained in Examples and Comparative Examples were coated on an aluminum foil (thickness 20 ⁇ m) and dried to obtain a positive electrode sheet having a thickness of 80 ⁇ m after drying. was punched out to a diameter of 11 mm to obtain a positive electrode layer. Further, a negative electrode layer was obtained by punching a metal lithium foil having a thickness of 100 ⁇ m into a diameter of 11 mm.
• the obtained coin battery was subjected to charge-discharge cycle evaluation at a voltage range of 3.0 to 4.2 V and a temperature of 25° C. using a charge-discharge tester (manufactured by Hokuto Denko Co., Ltd.).
• the capacity at the 100th cycle was calculated as the capacity retention rate (%) with respect to the initial discharge capacity.
• the obtained capacity retention rate was evaluated according to the following criteria. ⁇ : 90% or more ⁇ : 80% or more and less than 90% ⁇ : less than 80%
• a resin composition for a secondary battery electrode which is excellent in dispersibility of an active material, resistance to an electrolyte solution, and coating film density, and which is capable of achieving both high conductivity and adhesiveness. can be done.

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