Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/411—Organic material
  • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
  • C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
  • C08G12/40—Chemically modified polycondensates
  • C08G12/42—Chemically modified polycondensates by etherifying
• • 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
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/431—Inorganic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/431—Inorganic material
  • H01M50/434—Ceramics
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/431—Inorganic material
  • H01M50/434—Ceramics
  • H01M50/437—Glass
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/443—Particulate material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/409—Separators, membranes or diaphragms characterised by the material
  • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
  • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
  • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
  • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• • 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 coating material raw material for secondary battery separators, a coating material for secondary battery separators, a secondary battery separator, and a secondary battery, and more specifically to a coating material raw material for secondary battery separators, a coating material for secondary battery separators that contains the coating material raw material for secondary battery separators, a secondary battery separator that has a coating film of the coating material for secondary battery separators, and a secondary battery that has the secondary battery separator.
• secondary batteries are equipped with a separator that separates the positive and negative electrodes and allows ions in the electrolyte to pass through.
• One example of such a separator is a polyolefin porous membrane.
• a coating layer may be provided on the surface of the separator to impart various physical properties.
• a coating layer is formed, for example, by applying a coating material for secondary battery separators to the surface of the separator and drying it.
• a coating material for secondary battery separators contains a coating material raw material for secondary battery separators that contains a water-soluble polymer obtained by polymerizing a water-soluble polymer raw material that contains methacrylamide and methacrylic acid, and an inorganic filler (see, for example, Patent Document 1).
• the coating layer must be heat resistant.
• the present invention provides a coating material raw material for secondary battery separators that has excellent heat resistance and ion permeability, a coating material for secondary battery separators that contains the coating material raw material for secondary battery separators, a secondary battery separator that has a coating film of the coating material for secondary battery separators, and a secondary battery that has the secondary battery separator.
• the present invention [1] is a coating material raw material for secondary battery separators, which contains a resin that is a reaction product between a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol, or contains the modified methylolmelamine condensation resin having an acidic group and the polyvinyl alcohol.
• the present invention [2] includes the coating material raw material for secondary battery separators described in [1] above, which contains the resin and the acidic group is a sulfonic acid group.
• the present invention [3] includes the coating material raw material for secondary battery separators described in [1] above, which contains the modified methylol melamine condensation resin having the acidic group and the polyvinyl alcohol, and the content of the polyvinyl alcohol is 5 parts by mass or more and less than 50 parts by mass per 100 parts by mass of the modified methylol melamine condensation resin.
• the present invention [4] includes a coating material for a secondary battery separator, which contains the coating material raw material for a secondary battery separator described in any one of [1] to [3] above and inorganic particles.
• the present invention [5] includes a secondary battery separator comprising a porous membrane and a coating film of the coating material for secondary battery separators described in [4] above, which is disposed on at least one side of the porous membrane.
• the present invention [6] includes a secondary battery comprising a positive electrode, a negative electrode, and the secondary battery separator described in [5] above that is disposed between the positive electrode and the negative electrode.
• the coating material raw material for secondary battery separators of the present invention contains a resin that is a reaction product between a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol, or contains a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol. Therefore, it has excellent heat resistance and ion permeability.
• the coating material for secondary battery separators of the present invention contains the raw material for the coating material for secondary battery separators of the present invention. Therefore, it has excellent heat resistance and ion permeability.
• the secondary battery separator of the present invention is provided with a coating film of the coating material for secondary battery separators of the present invention. Therefore, it has excellent heat resistance and ion permeability.
• the secondary battery of the present invention is equipped with the secondary battery separator of the present invention. Therefore, it has excellent heat resistance and ion permeability.
• the coating material raw material for secondary battery separators contains a resin that is a reaction product of a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol, or contains a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol.
• a resin that is a reaction product of a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol or contains a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol.
• the coating material raw material for secondary battery separators includes a resin that is a reaction product of a modified methylolmelamine condensation resin having acidic groups and polyvinyl alcohol.
• the resin is a reaction product of modified methylolmelamine condensation resin with acidic groups and polyvinyl alcohol.
• modified methylolmelamine condensation resin having an acidic group (hereinafter, may be referred to as modified methylolmelamine condensation resin) is a condensation polymer of modified methylolmelamine.
• Modified methylol melamine is a reaction product between methylol melamine and an acid component.
• Methylolmelamine is the reaction product of melamine with formaldehyde or paraformaldehyde, which, when used, is hydrolyzed to formaldehyde and then reacted with melamine.
• the amount of formaldehyde to be blended per mole of melamine will be described in detail later, but from the viewpoint of increasing the molecular weight, it is, for example, 3.0 or more, preferably more than 3.0, more preferably 3.2 or more, and even more preferably 3.3 or more, and for example, 5.0 or less, preferably 4.0 or less.
• the heating temperature is, for example, 40°C or higher, preferably 50°C or higher, and for example, 90°C or lower, preferably 80°C or lower.
• the heating time is, for example, 0.5 hours or higher, preferably 2 hours or higher, and for example, 6 hours or lower.
• the pH is 3.0 or more, preferably 4.0 or more, more preferably 8.0 or more, even more preferably 9.0 or more, particularly preferably 10.0 or more, and for example, 13.0 or less, preferably 12.0 or less, more preferably 11.8 or less.
• the pH can be adjusted by adding an alkali (e.g., sodium hydroxide).
• melamine (general formula (1-1) below) reacts with formaldehyde (general formula (1-2) below) to produce methylolmelamine (general formula (1-3) below).
• the methylol melamine (general formula (1-3) above) is trimethylol melamine in which three of the six hydrogen atoms in the amino group of melamine have been modified to methylol groups, or the methylol melamine is tetramethylol melamine in which four of the six hydrogen atoms in the amino group of melamine have been modified to methylol groups.
• modified methylol melamine is the reaction product of methylol melamine with an acid component.
• the acid component is a component capable of reacting with the methylol groups of methylol melamine.
• the acid component is a component that introduces acidic groups into methylol melamine by reacting with the methylol groups of methylol melamine.
• acid components include carboxylic acids, phosphoric acids, and sulfurous acids.
• carboxylic acids examples include maleic acid, succinic acid, phthalic acid, formylbenzoic acid, aminobenzoic acid, acrylic acid, methacrylic acid, and amino acids (e.g., glycine).
• Carboxylic acids also include their salts and anhydrides. Examples of salts of carboxylic acids include sodium maleate and sodium succinate. Examples of anhydrides of carboxylic acids include maleic anhydride, succinic anhydride, and phthalic anhydride.
• Examples of phosphoric acid include phosphonobenzoic acid and aminophenylphosphonic acid. Phosphoric acid also includes salts thereof. An example of a salt of phosphoric acid is sodium phosphonobenzoate.
• Sulfurous acid includes, for example, sulfobenzoic acid, formylbenzenesulfonic acid, sulfanilic acid, pyrosulfite, and sulfurous acid.
• Sulfurous acid includes its salts.
• Sulfurous acid salts include, for example, sodium hydrogen sulfite, sodium sulfite, and sodium pyrosulfite.
• Sulfurous acid is preferably sodium hydrogen sulfite, sulfanilic acid, and sodium pyrosulfite.
• Sulfurous acid is more preferably sodium hydrogen sulfite.
• the acid component is preferably sulfurous acid.
• the acid components can be used alone or in combination of two or more types.
• Modified methylol melamine is obtained by reacting methylol melamine with an acid component.
• the amount of the acid component is, for example, 0.44 mol or more, preferably 0.50 mol or more, more preferably 0.60 mol or more, even more preferably 0.70 mol or more, and for example, 1.00 mol or less, preferably 0.90 mol or less, more preferably 0.80 mol or less, per mol of methylol melamine.
• the heating temperature is, for example, 50°C or higher, preferably 70°C or higher, and for example, 100°C or lower, preferably 90°C or lower.
• the heating time is, for example, 0.5 hours or higher, preferably 1 hour or higher, and for example, 6 hours or lower.
• methylol melamine reacts with the acid component to obtain modified methylol melamine. More specifically, one of the methylol groups in methylol melamine can be modified by the acid component into an acidic group derived from the acid component.
• the modified methylol melamine has an acidic group derived from the acid component. More specifically, when the acid component is a carboxylic acid, the modified methylol melamine has a carboxyl group as the acidic group. When the acid component is phosphoric acid, the modified methylol melamine has a phosphoric acid group as the acidic group. When the acid component is sulfurous acid, the modified methylol melamine has a sulfonic acid group as the acidic group. The acidic group is preferably a sulfonic acid group.
• methylol melamine (general formula (1-3) below) reacts with sodium hydrogen sulfite (general formula (2-1) below) to give modified methylol melamine (general formula (2-2) below).
• the modified methylol melamine represented by the general formula (2-2) below has a sulfonic acid group as an acidic group.
• the modified methylol melamine is preferably the modified methylol melamine represented by the above general formula (2-2).
• modified methylolmelamine condensation resin is a condensation polymer of modified methylolmelamine (modified methylolmelamine having an acidic group).
• the method for producing modified methylolmelamine condensation resin will be described later.
• Polyvinyl alcohol is a component that imparts wettability and improves adhesion when this resin is used as a raw material for a coating material for a secondary battery separator.
• polyvinyl alcohol examples include unmodified polyvinyl alcohol and modified polyvinyl alcohol.
• modified polyvinyl alcohol examples include anionic group-modified polyvinyl alcohol (e.g., carboxyl group-modified polyvinyl alcohol, sulfo group-modified polyvinyl alcohol) and hydrophobic group-modified polyvinyl alcohol.
• modified polyvinyl alcohol is anionic group-modified polyvinyl alcohol.
• Modified polyvinyl alcohol is more preferably, carboxyl group-modified polyvinyl alcohol.
• the polyvinyl alcohol is preferably modified polyvinyl alcohol.
• the saponification degree of polyvinyl alcohol is, for example, 70 mol% or more, preferably 85 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and, for example, 100 mol% or less, preferably 99 mol% or less.
• Polyvinyl alcohol can be used alone or in combination of two or more types.
• Polyvinyl alcohol can also be prepared as an aqueous solution of polyvinyl alcohol.
• the solids concentration of polyvinyl alcohol is, for example, 5% by mass or more and, for example, 50% by mass or less.
• the resin is obtained by reacting a modified methylolmelamine condensation resin with polyvinyl alcohol.
• the resin is obtained by producing a modified methylolmelamine condensation resin by dehydrating and condensing modified methylolmelamine, and then reacting this modified methylolmelamine condensation resin with polyvinyl alcohol.
• this type of resin is distinct from a resin obtained by dehydrating and condensing modified methylolmelamine to obtain a modified methylolmelamine condensation resin, and then reacting it with vinyl alcohol.
• modified methylol melamine and polyvinyl alcohol are mixed with water.
• the modified methylol melamine is dehydrated and condensed, and the modified methylol melamine condensation resin obtained by the dehydration and condensation is reacted with polyvinyl alcohol.
• modified methylol melamine condensation resin reacts with polyvinyl alcohol
• the methylol groups of the modified methylol melamine condensation resin react with the hydroxyl groups of the polyvinyl alcohol.
• the reaction between methylol groups and hydroxyl groups is described, for example, in Journal of Cleaner Production Volume 255, 10 May 2020, 120062, 'Efficient removal of Congo red dye from aqueous solution by adsorbent films of polyvinyl alcohol/melamine-formaldehyde composite and bacterial effects'.
• an acid e.g., sulfuric acid
• the mixture is heated in water at a pH of 5 or more but less than 8.
• the heating temperature is, for example, 50°C or higher, preferably 60°C or higher, and for example, 90°C or lower, preferably 80°C or lower.
• the heating time is, for example, 1 hour or longer, preferably 2 hours or longer, and for example, 6 hours or shorter.
• the blending ratio of modified methylol melamine is, for example, 70 parts by mass or more, preferably 80 parts by mass or more, more preferably 85 parts by mass or more, and for example, 99 parts by mass or less, preferably 95 parts by mass or less, per 100 parts by mass of the total amount of modified methylol melamine and polyvinyl alcohol.
• the proportion of polyvinyl alcohol is, for example, 1 part by mass or more, preferably 5 parts by mass or more, and, for example, 30 parts by mass or less, preferably 20 parts by mass or less, more preferably 15 parts by mass or less, per 100 parts by mass of the total amount of modified methylol melamine and polyvinyl alcohol.
• the modified methylol melamine condensation resin reacts with the polyvinyl alcohol to produce a resin (aqueous solution of the resin).
• reaction from melamine to resin described above can be carried out continuously or in separate steps.
• the solids concentration of the modified methylol melamine condensation resin is, for example, 10% by mass or more, preferably 15% by mass or more, and, for example, 40% by mass or less.
• Such resins have the same acidic groups as modified methylol melamine.
• methylol melamine is reacted with an acid component to obtain modified methylol melamine, and then the modified methylol melamine is dehydrated and condensed to obtain a modified methylol melamine condensation resin.
• the modified methylol melamine is dehydrated and condensed to obtain a modified methylol melamine condensation resin.
• the amount of acid component not all of the methylol melamine may react with the acid component, and some methylol melamine may remain. In such cases, the three methylol groups in the methylol melamine and the two methylol groups in the modified methylol melamine are condensed.
• the resin is a reaction product between a modified methylolmelamine condensation resin with acidic groups and polyvinyl alcohol. As a result, it has excellent heat resistance, ion permeability and storage stability.
• the raw material for the coating material for secondary battery separators contains the above resin (aqueous solution of the above resin).
• additives such as wetting agents, dispersants, hydrophilic resins, moistening agents, defoamers, and pH adjusters can be blended in appropriate proportions into the coating material raw material for secondary battery separators, if necessary.
• the coating material raw material for secondary battery separators contains additives, if necessary.
• the additives can be blended during and/or after the production of the above-mentioned resins.
• this coating material raw material for secondary battery separators has excellent wettability because it contains a resin obtained using polyvinyl alcohol. Therefore, the coating material raw material for secondary battery separators has excellent wettability even without containing a wetting agent.
• the coating material raw material for secondary battery separators preferably contains the above-mentioned resin and does not contain a wetting agent.
• the solid content concentration of the above resin is, for example, 10% by mass or more, preferably 15% by mass or more, and, for example, 40% by mass or less.
• the raw material for the coating material for secondary battery separators contains the above resin. Therefore, it has excellent heat resistance, ion permeability, and storage stability.
• the raw material for the coating material for secondary battery separators contains a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol.
• the modified methylol melamine condensation resin having an acidic group is the same as the modified methylol melamine condensation resin having an acidic group in the first invention. That is, the modified methylol melamine condensation resin having an acidic group is a condensation polymer of modified methylol melamine.
• the modified methylol melamine is a reaction product of methylol melamine and an acid component.
• Methylolmelamine is the reaction product of melamine and formaldehyde.
• the amount of formaldehyde per mole of melamine is, for example, 2.4 moles or more, preferably 2.6 moles or more, more preferably 2.8 moles or more, even more preferably 2.9 moles or more, and for example, 5.0 moles or less, preferably 4.0 moles or less, more preferably 3.3 moles or less, even more preferably 3.1 moles or less.
• the amount of formaldehyde per mole of melamine is equal to or greater than the lower limit and equal to or less than the upper limit, almost all of the three amino groups in the melamine can be modified to methylol groups.
• heating temperature, heating time, and pH for the reaction of melamine with formaldehyde are the same as those in the first invention.
• methylol melamine trimethylol melamine is used, in which all three amino groups in melamine have been modified to methylol groups.
• modified methylol melamine is a reaction product of methylol melamine and an acid component.
• the acid component may be any of the acid components listed in the first invention.
• a preferred acid component is sulfurous acid.
• the acid components can be used alone or in combination of two or more types.
• modified methylol melamine is obtained by reacting methylol melamine with an acid component. Specifically, to react methylol melamine with an acid component, water, methylol melamine, and the acid component are mixed and heated.
• the amount of the acid component is, for example, 0.10 mol or more, preferably 0.15 mol or more, more preferably 0.30 mol or more, even more preferably 0.40 mol or more, particularly preferably 0.43 mol or more, and, for example, less than 0.70 mol, preferably 0.65 mol or less, more preferably 0.60 mol or less, even more preferably 0.50 mol or less, per mol of methylol melamine.
• the heating conditions are the same as those in the first invention.
• methylol melamine reacts with the acid component to obtain modified methylol melamine.
• one of the methylol groups in methylol melamine can be modified by the acid component to an acidic group derived from the acid component.
• a preferred example of the acidic group is sulfonic acid.
• modified methylol melamine condensation resin having acidic groups is a condensation polymer of modified methylol melamine (modified methylol melamine having acidic groups).
• the pH is adjusted to 5 or more and less than 8 by adding an acid (e.g., sulfuric acid) and heating the modified methylol melamine in water.
• an acid e.g., sulfuric acid
• the heating temperature is, for example, 50°C or higher, preferably 60°C or higher, and for example, 90°C or lower, preferably 80°C or lower.
• the heating time is, for example, 1 hour or longer, preferably 2 hours or longer, and for example, 6 hours or shorter.
• an alkali e.g., sodium hydroxide
• an alkali e.g., sodium hydroxide
• the two methylol groups in the modified methylol melamine undergo dehydration condensation to obtain a modified methylol melamine condensation resin (aqueous dispersion of modified methylol melamine condensation resin).
• reaction from melamine to the modified methylol melamine condensation resin described above can be carried out continuously or in portions.
• the solids concentration of the modified methylol melamine condensation resin is, for example, 10% by mass or more, preferably 15% by mass or more, and, for example, 40% by mass or less.
• modified methylol melamine condensation resins have the same acidic groups as modified methylol melamine.
• the content of the modified methylol melamine condensation resin is, for example, 60 parts by mass or more, preferably 70 parts by mass or more, more preferably 80 parts by mass or more, and for example, 98 parts by mass or less, preferably 90 parts by mass or less, per 100 parts by mass of the total amount of the modified methylol melamine condensation resin and polyvinyl alcohol.
• methylol melamine is reacted with an acid component to obtain modified methylol melamine, and then the modified methylol melamine is dehydrated and condensed to obtain a modified methylol melamine condensation resin.
• the modified methylol melamine is dehydrated and condensed to obtain a modified methylol melamine condensation resin.
• the amount of acid component not all of the methylol melamine may react with the acid component, and some methylol melamine may remain. In such cases, the three methylol groups in the methylol melamine and the two methylol groups in the modified methylol melamine are condensed.
• the polyvinyl alcohol may be the polyvinyl alcohol mentioned in the first aspect of the invention.
• the polyvinyl alcohol may preferably be an anionic group-modified polyvinyl alcohol.
• the modified polyvinyl alcohol may more preferably be a carboxyl group-modified polyvinyl alcohol.
• the saponification value of the polyvinyl alcohol is the same as that described in the first invention.
• Polyvinyl alcohol can be used alone or in combination of two or more types.
• the content of polyvinyl alcohol is, for example, 3 parts by mass or more, preferably 5 parts by mass or more from the viewpoint of improving heat resistance, more preferably 6 parts by mass or more, even more preferably 10 parts by mass or more, and for example, 60 parts by mass or less, preferably less than 50 parts by mass from the viewpoint of improving heat resistance and ion permeability, more preferably 40 parts by mass or less, even more preferably 30 parts by mass or less, and particularly preferably 20 parts by mass or less, per 100 parts by mass of modified methylol melamine condensation resin.
• the content of polyvinyl alcohol is, for example, 2 parts by mass or more, preferably 10 parts by mass or more from the viewpoint of improving heat resistance, and, for example, 40 parts by mass or less, preferably 30 parts by mass or less from the viewpoint of improving heat resistance and ion permeability, more preferably 20 parts by mass or less, relative to 100 parts by mass of the total amount of modified methylol melamine condensation resin and polyvinyl alcohol.
• Polyvinyl alcohol can also be prepared as an aqueous solution of polyvinyl alcohol.
• the solids concentration of polyvinyl alcohol is, for example, 5% by mass or more and, for example, 50% by mass or less.
• the raw material for the coating material for secondary battery separators is prepared by separately preparing a modified methylolmelamine condensation resin having an acidic group (aqueous dispersion of the modified methylolmelamine condensation resin) and polyvinyl alcohol as separate packages, which are then mixed together at the time of use.
• additives such as wetting agents, dispersants, hydrophilic resins, moistening agents, defoamers, and pH adjusters can be blended in appropriate proportions into the coating material raw material for secondary battery separators, if necessary.
• the coating material raw material for secondary battery separators contains additives if necessary.
• the additives can be blended into the modified methylol melamine condensation resin and/or polyvinyl alcohol having acidic groups.
• this coating material raw material for secondary battery separators has excellent wettability because it contains a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol. Therefore, the coating material raw material for secondary battery separators has excellent wettability even without containing a wetting agent.
• the coating material raw material for secondary battery separators preferably contains a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol, but does not contain a wetting agent.
• the raw material for the coating material for secondary battery separators contains modified methylolmelamine condensation resin with acidic groups and polyvinyl alcohol, and therefore has excellent heat resistance and ion permeability.
• coating material raw materials for secondary battery separators can be particularly suitably used as raw materials for coating materials for secondary battery separators.
• the following provides a detailed description of the coating material for secondary battery separators obtained using this raw material for the coating material for secondary battery separators.
• the coating material for secondary battery separator contains the above-mentioned coating material raw material for secondary battery separator and inorganic particles.
• Inorganic particles include, for example, oxides, nitrides, carbides, sulfates, hydroxides, and potassium titanate.
• Oxides include, for example, alumina, silica, titania, zirconia, magnesia, ceria, yttria, zinc oxide, and iron oxide.
• Nitrides include, for example, silicon nitride, titanium nitride, and boron nitride.
• Carbides include, for example, silicon carbide and calcium carbonate.
• Sulfates include, for example, magnesium sulfate and aluminum sulfate.
• Hydroxides include, for example, aluminum hydroxide and aluminum oxide hydroxide.
• Silicates include, for example, talc, kaolinite, dickite, nacrite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amesite, bentonite, asbestos, zeolite, calcium silicate, magnesium silicate, diatomaceous earth, silica sand, and glass.
• the inorganic particles are hydroxides. More preferably, the inorganic particles are aluminum oxide hydroxide.
• the average median diameter D50 of the inorganic particles is, for example, 0.1 ⁇ m or more, preferably 0.5 ⁇ m or more, and, for example, 5 ⁇ m or less, preferably 1 ⁇ m or less.
• Inorganic particles can be used alone or in combination of two or more types.
• the coating material for secondary battery separators To manufacture the coating material for secondary battery separators, first, inorganic particles and, if necessary, a dispersant are mixed with water to prepare an aqueous dispersion of inorganic particles. If a dispersant is mixed, the coating material for secondary battery separators contains the dispersant.
• dispersants examples include ammonium polycarboxylate and sodium polycarboxylate. Preferably, ammonium polycarboxylate is used as the dispersant.
• the mixing ratio of the dispersant is, for example, 0.1 parts by mass or more, preferably 0.5 parts by mass or more, and, for example, 10 parts by mass or less, preferably 3 parts by mass or less, per 100 parts by mass of inorganic particles.
• Dispersants can be used alone or in combination of two or more types.
• the raw material for the coating material for secondary battery separators (aqueous dispersion of the raw material for the coating material for secondary battery separators) is mixed into the aqueous dispersion of inorganic particles and stirred.
• the stirring method is not particularly limited, and examples include a ball mill, a bead mill, a planetary ball mill, a vibrating ball mill, a sand mill, a colloid mill, an attritor, a roll mill, a high-speed impeller dispersion, a stirrer, a disperser, a homogenizer, a high-speed impact mill, an ultrasonic dispersion, and a stirring blade.
• the above-mentioned additives can be blended in an appropriate ratio into the coating material for secondary battery separators.
• the coating material for secondary battery separators contains the above-mentioned additives if necessary.
• the coating material for secondary battery separators preferably does not contain a wetting agent.
• additives can be used alone or in combination of two or more types.
• this type of coating material for secondary battery separators is obtained as an aqueous dispersion in which it is dispersed in water.
• the solids concentration of the aqueous dispersion of the coating material for secondary battery separators is, for example, 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, and for example, 50% by mass or less.
• the content of the coating material raw material (solid content) for secondary battery separators is, for example, 3.0 parts by mass or more, preferably 4.2 parts by mass or more, and 10.0 parts by mass or less, preferably 7.0 parts by mass or less, and more preferably 6.0 parts by mass or less, per 100 parts by mass of the total amount of the coating material raw material (solid content) for secondary battery separators and the inorganic particles.
• the content of the inorganic particles is, for example, 90.0 parts by mass or more, preferably 93.0 parts by mass or more, and more preferably 94.0 parts by mass or more, and for example, 97.0 parts by mass or less, preferably 95.8 parts by mass or less, per 100 parts by mass of the coating material raw material (solid content) for secondary battery separators and the inorganic particles.
• the content of the raw material (solid content) for the coating material for secondary battery separators is, for example, 3.0 parts by mass or more, preferably 4.0 parts by mass or more, more preferably 4.4 parts by mass or more, and for example, 10.0 parts by mass or less, preferably 7.0 parts by mass or less, more preferably 6.0 parts by mass or less, and even more preferably 5.0 parts by mass or less, per 100 parts by mass of the total amount of inorganic particles.
• the coating material for secondary battery separators contains the raw materials for the coating material for secondary battery separators. Therefore, secondary battery separators equipped with a coating film obtained using this coating material for secondary battery separators have excellent heat resistance and ion permeability.
• the secondary battery separator comprises a porous membrane and a coating film of a coating material for secondary battery separators arranged on at least one side of the porous membrane.
• porous membrane examples include polyolefin porous membranes and aromatic polyamide porous membranes. Examples of the polyolefin porous membrane include polyethylene porous membranes and polypropylene porous membranes. Examples of the porous membrane include polyolefin porous membranes.
• the thickness of the porous membrane is, for example, 1 ⁇ m or more, preferably 5 ⁇ m or more, and, for example, 40 ⁇ m or less, preferably 20 ⁇ m or less.
• the coating film imparts heat resistance to the porous film.
• the coating film is made of a coating material for a secondary battery separator.
• the thickness of the coating film is, for example, 1 ⁇ m or more, and, for example, 10 ⁇ m or less, preferably 8 ⁇ m or less.
• the method for producing a secondary battery separator includes a first step of preparing a porous membrane, and a second step of applying a separator coating material to at least one surface of the porous membrane.
• a coating material for a secondary battery separator is applied to at least one surface of the porous membrane, and then dried as necessary to obtain a coating film.
• the secondary battery separator comprises a porous membrane, a surface treatment layer, and a coating film of the coating material for secondary battery separators.
• Surface treatments include, for example, corona discharge treatment, glow discharge treatment, plasma treatment, and ozone treatment.
• no surface treatment is performed from the viewpoint of improving ion permeability.
• the secondary battery separator preferably does not include a surface treatment layer.
• the coating method for applying the coating material for secondary battery separators is not particularly limited, and examples include the wire bar method, gravure coater method, small diameter gravure coater method, reverse roll coater method, transfer roll coater method, kiss coater method, dip coater method, microgravure coat method, knife coater method, air doctor coater method, blade coater method, rod coater method, squeeze coater method, cast coater method, die coater method, screen printing method, and spray coating method.
• the wire bar method is preferably used as the coating method.
• the drying temperature is, for example, 40°C or higher and, for example, 80°C or lower.
• a coating film of a coating material for a secondary battery separator is disposed on at least one side of the porous membrane, but the above coating film can also be disposed on both sides of the porous membrane.
• This secondary battery separator has a coating film of the above-mentioned coating material for secondary battery separators. Therefore, the secondary battery separator has excellent heat resistance and ion permeability. Therefore, this secondary battery separator can be suitably used in the manufacture of secondary batteries.
• the secondary battery includes a positive electrode, a negative electrode, the above-mentioned secondary battery separator disposed between the positive electrode and the negative electrode, and an electrolyte impregnated in the positive electrode, the negative electrode, and the above-mentioned secondary battery separator.
• the positive electrode for example, a known electrode having a positive electrode current collector and a positive electrode active material laminated on the positive electrode current collector is used.
• positive electrode current collectors include conductive materials such as aluminum, titanium, stainless steel, nickel, baked carbon, conductive polymers, and conductive glass.
• the positive electrode active material is not particularly limited, but examples include known positive electrode active materials such as lithium-containing transition metal oxides, lithium-containing phosphates, and lithium-containing sulfates.
• These positive electrode active materials can be used alone or in combination of two or more types.
• the negative electrode for example, a known electrode having a negative electrode current collector and a negative electrode active material laminated on the negative electrode current collector is used.
• negative electrode current collectors examples include conductive materials such as copper and nickel.
• the negative electrode active material is not particularly limited, but may be a carbon active material.
• Examples of the carbon active material include graphite, soft carbon, and hard carbon.
• These negative electrode active materials can be used alone or in combination of two or more types.
• the electrolyte may be, for example, a solution in which a lithium salt is dissolved in a carbonate compound such as ethylene carbonate (EC), propylene carbonate (PC), or ethyl methyl carbonate (EMC).
• EC ethylene carbonate
• PC propylene carbonate
• EMC ethyl methyl carbonate
• a separator for the secondary battery is sandwiched between a positive electrode and a negative electrode, and these are housed in a battery casing (cell), and an electrolyte is injected into the battery casing. This produces a secondary battery.
• the secondary battery is equipped with the secondary battery separator. Therefore, it has excellent heat resistance and ion permeability.
• the raw material for the coating material for secondary battery separator contains a resin which is a reaction product between a modified methylolmelamine condensation resin having an acidic group and polyvinyl alcohol, and therefore has excellent heat resistance and ion permeability.
• the resin is obtained using a modified methylolmelamine condensation resin that has an acidic group that has excellent heat resistance. Therefore, it has excellent heat resistance.
• the resin since the resin is obtained using polyvinyl alcohol, it has excellent wettability. This allows the coating film to be formed uniformly. This in turn improves heat resistance and ion permeability.
• the resin has excellent wettability, for example, when a raw material for a coating material for a secondary battery separator containing this resin is applied to the surface of a porous membrane, a coating film can be formed without subjecting the surface of the porous membrane to surface treatment (e.g., corona discharge treatment).
• surface treatment e.g., corona discharge treatment
• this coating material for secondary battery separators allows a coating film to be formed on the surface of the porous membrane without surface treatment, so it is possible to prevent part of the coating material for secondary battery separators from penetrating into the pores of the porous membrane. This further improves ion permeability.
• This resin also has excellent storage stability.
• this resin is obtained by dehydrating and condensing modified methylolmelamine, and reacting the modified methylolmelamine condensation resin having acidic groups obtained by the dehydrating and condensing with polyvinyl alcohol in advance.
• polyvinyl alcohol is added in advance.
• the above gelling can be suppressed by reacting the modified methylol melamine condensation resin with polyvinyl alcohol in advance.
• the reason for this is unclear, but by reacting the modified methylol melamine resin with polyvinyl alcohol in advance, the hydroxyl groups of the polyvinyl alcohol are consumed in the reaction, so the hydroxyl groups of the polyvinyl alcohol are reduced during storage, and it is presumed that this improves storage stability.
• the coating material raw material for secondary battery separators contains a modified methylolmelamine condensation resin having acidic groups and polyvinyl alcohol. Therefore, it has excellent heat resistance and ion permeability.
• the raw material for the coating material for secondary battery separators contains modified methylolmelamine condensation resin that has acidic groups that have excellent heat resistance. Therefore, it has excellent heat resistance.
• the raw material for the coating material for secondary battery separators contains polyvinyl alcohol, which gives it excellent wettability. This allows the coating film to be formed uniformly. This in turn improves heat resistance and ion permeability.
• a coating film can be formed on the surface of the porous membrane without performing surface treatment (e.g., corona discharge treatment).
• this coating material for secondary battery separators allows a coating film to be formed on the surface of the porous membrane without surface treatment, so it is possible to prevent part of the coating material for secondary battery separators from penetrating into the pores of the porous membrane. This further improves ion permeability.
• the coating material for secondary battery separators contains the above-mentioned raw materials for coating material for secondary battery separators. Therefore, it has excellent heat resistance and ion permeability.
• the secondary battery separator is provided with a coating film of the above-mentioned coating material for secondary battery separators. This provides excellent heat resistance and ion permeability.
• the secondary battery is equipped with the above-mentioned secondary battery separator. Therefore, it has excellent heat resistance and ion permeability.
• Gohsenex CKS-50 sulfo group-modified polyvinyl alcohol, saponification degree 99 mol%, manufactured by Mitsubishi Chemical Corporation
• Gohsenex WO-320 hydrophilic group-modified polyvinyl alcohol, saponification degree 98.5 mol%, manufactured by Mitsubishi Chemical Corporation
• Kuraray Poval 5-98 unmodified polyvinyl alcohol, saponification degree 98 mol% to 99 mol%, manufactured by Kuraray Co., Ltd.
• Kuraray Poval 60-98 unmodified polyvinyl Alcohol, saponification value 98 mol% to 99 mol%, manufactured by Kuraray Co., Ltd.
• Kuraray Poval 44-88 Unmodified polyvinyl alcohol, saponification value 87 mol% to 89 mol%, manufactured by Kuraray Co., Ltd.
• Kuraray Poval 5-74 Unmodified polyvinyl alcohol, saponification value 72.5 to 74.5 mol%, manufactured by Kuraray Co., Ltd.
• Wetting agent Acetylene-based surfactant, Olfin E1010, manufactured by Nissin Chemical Industry Co., Ltd.
• Ammonium polycarboxylate Dispersant, ammonium polycarboxylate aqueous solution, product name SN5468, manufactured by San Nopco Ltd.
• Production Examples 2 to 4 A resin (aqueous solution of resin) (solid content concentration 16% by mass) was obtained according to the same procedure as in Production Example 1. However, the formulation of each component was changed according to Table 1. The values in Table 1 are parts by mass (solid content).
• Reference Manufacturing Example 1 692.0 parts by mass of water and 277.8 parts by mass of 37% formaldehyde were charged into a four-neck flask equipped with a stirrer, a thermometer, and a reflux condenser, and mixed by stirring. Furthermore, 144.0 parts of melamine were added under stirring. The temperature was raised to 60°C, and the pH was adjusted to 11.0 with a 25% aqueous sodium hydroxide solution, and then the mixture was reacted at 75°C for 3 hours and cooled to 60°C. As a result, methylol melamine was obtained.
• Example 1 Manufacturing raw materials for coating materials for secondary battery separators
• the resin of Production Example 1 was used as a raw material for a coating material for a secondary battery separator.
• a dispersant was added to 123 parts by mass of water according to the formulation shown in Table 2. Next, while stirring with a disperser (1000 rpm), 100 parts by mass of boehmite (aluminum oxide hydroxide, manufactured by Navaltec, product name "Apilar AOH60", average median diameter D50: 0.9 ⁇ m) was gradually added as inorganic particles. After the addition, the mixture was further stirred with a homogenizer (5000 rpm). This resulted in an aqueous dispersion of inorganic particles (solid content concentration of inorganic particles: 45% by mass).
• boehmite aluminum oxide hydroxide, manufactured by Navaltec, product name "Apilar AOH60", average median diameter D50: 0.9 ⁇ m
• the raw material for the coating material for secondary battery separators was mixed into the aqueous dispersion of inorganic particles, and water was added appropriately and stirred.
• Example 2 Comparative Example 1 and Reference Example 1 Based on the same procedure as in Example 1, a coating material raw material for a secondary battery separator, a coating material for a secondary battery separator, and a secondary battery separator were obtained. However, the formulation of each component was changed according to Table 2. The numerical values in Table 2 are parts by mass (solid content).
• a coating material for a secondary battery separator was produced by blending an aqueous solution of the water-soluble polymer of Production Comparative Example 1, which is a coating material raw material for a secondary battery separator, and E1010.
• a coating material for a secondary battery separator was produced by blending a resin of Production Reference Example 1, which is a coating material raw material for a secondary battery separator, and an aqueous solution of AF (10%).
• Examples 1 to 4 in which polyvinyl alcohol is added beforehand, have superior storage stability compared to Reference Example 1, in which polyvinyl alcohol is added later.
• Production Example 6 692.0 parts by mass of water and 259.3 parts by mass (3.20 moles) of 37% formaldehyde were charged into a four-neck flask equipped with a stirrer, a thermometer, and a reflux condenser, and mixed by stirring. Furthermore, 144.0 parts by mass (1.14 moles) of melamine were added under stirring. The mixture was heated to 60°C, and the pH was adjusted to 11.0 with a 25% aqueous sodium hydroxide solution, and then reacted at 75°C for 3 hours and cooled to 60°C. As a result, methylol melamine was obtained.
• Each polyvinyl alcohol (Kuraray Poval 60-98, AF17, Kuraray Poval 44-88, Kuraray Poval 5-74) was prepared as follows. Specifically, 100 parts by mass of water was charged into a separable flask equipped with a stirrer, and 10 parts by mass of polyvinyl alcohol was added little by little while stirring, and then the temperature was raised to 95°C and maintained for 3 hours. After confirming that the polyvinyl alcohol was completely dissolved, the mixture was cooled and an appropriate amount of water was added to prepare a 10% aqueous solution of polyvinyl alcohol.
• a dispersant was added to 123 parts by mass of water according to the formulation shown in Table 3. Next, while stirring with a disperser (1000 rpm), 100 parts by mass of boehmite (aluminum oxide hydroxide, manufactured by Navaltec, product name "Apilar AOH60", average median diameter D50: 0.9 ⁇ m) was gradually added as inorganic particles. After the addition, the mixture was further stirred with a homogenizer (5000 rpm). This resulted in an aqueous dispersion of inorganic particles (solid content concentration of inorganic particles: 45% by mass).
• boehmite aluminum oxide hydroxide, manufactured by Navaltec, product name "Apilar AOH60", average median diameter D50: 0.9 ⁇ m
• the raw material for the coating material for the secondary battery separator was mixed into the aqueous dispersion of inorganic particles (specifically, a modified methylolmelamine condensation resin (or a water-soluble acrylic polymer) having acidic groups and polyvinyl alcohol, which were prepared separately, were mixed and mixed), and water was added appropriately and the mixture was stirred.
• inorganic particles specifically, a modified methylolmelamine condensation resin (or a water-soluble acrylic polymer) having acidic groups and polyvinyl alcohol, which were prepared separately, were mixed and mixed
• the coating material raw material for secondary battery separators, the coating material for secondary battery separators, and the secondary battery separators of the present invention are suitable for use in the manufacture of secondary batteries.

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