JP2015151402A - Acid modified polyolefin resin aqueous dispersoid, secondary battery electrode using the same and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acid modified polyolefin resin aqueous dispersoid excellent in adhesiveness, chemical resistance (solvent resistance), pH stability and metal ion mixing stability and a binder for secondary battery electrode exhibiting excellent adhesiveness to an active product, an auxiliary conductive agent, a metal collector or the like, excellent in swelling resistance to an electrolyte and exhibiting excellent electrode slurry stability.SOLUTION: There is provided an acid modified polyolefin resin aqueous dispersoid containing (A) an acid modified polyolefin resin having an unsaturated carboxylic acid component of 0.5 to 20 mass% and (B) an alkali metal hydroxide as a basic compound.

Description

The present invention relates to an acid-modified polyolefin resin aqueous dispersion containing a specific alkali metal hydroxide (B), a secondary battery electrode and a secondary battery using the same.

It is known that an acid-modified polyolefin resin aqueous dispersion is used as a binder for a secondary battery electrode because of its excellent adhesion and chemical resistance. A lithium ion secondary battery, which is a typical example of a secondary battery, generally has a structure in which an electrode manufactured via a separator is accommodated in a container together with an electrolyte between a positive electrode and a negative electrode.
An electrode used for a lithium ion secondary battery was formed by applying a slurry made of an active material, a conductive assistant mainly made of a carbon material, and a binder onto a metal current collector such as an aluminum foil or a copper foil. The binder is required to have excellent adhesion between the active material and the conductive assistant, and these and the metal current collector, and resistance to swelling with respect to the electrolytic solution.

As an active material for a positive electrode of a lithium ion secondary battery, lithium cobaltate has been widely used in the past, but for the purpose of stable supply and for improving battery performance such as higher potential and higher output of the battery, In recent years, lithium-containing transition metal oxides based on lithium nickelate and lithium manganate have been proposed. When preparing a slurry by mixing these positive electrode active materials and binders, the pH rises due to the elution of lithium from the active materials, and aggregates are generated and the viscosity of the slurry is increased. Therefore, it was necessary to adjust the pH (Patent Documents 1 to 3).
In addition, the binder used in the slurry for electrode formation is required to have mixing stability with respect to metal ions so as not to generate agglomerates due to metal ions eluted from lithium oxide as an active material and to cause thickening and solidification of the slurry. In addition, the slurry is also required to have stability over time with respect to the progress of elution of pH and metal ions due to ionization of a part of the active material and impurities. However, there has been no binder that satisfies such requirements.

Patent Document 1 Japanese Patent Application Laid-Open No. 2000-106186 Patent Document 2 Japanese Patent Application Laid-Open No. 2002-141059 Japanese Patent Application Laid-Open No. 2011-192644

The present invention solves the above-described problems, and an object thereof is to provide an acid-modified polyolefin resin aqueous dispersion excellent in adhesiveness, chemical resistance (solvent resistance), pH stability and metal ion mixing stability. And In addition, the present invention provides a secondary battery electrode binder that exhibits excellent adhesion to an active material, a conductive additive, a metal current collector, etc., excellent swelling resistance to an electrolyte, and excellent electrode slurry stability. The purpose is to provide.

As a result of intensive studies, the present inventors have found that an acid-modified polyolefin resin aqueous dispersion containing an alkali metal hydroxide (B) can solve the above-mentioned problems, and have reached the present invention.

That is, the gist of the present invention is as follows.

(1) An acid-modified polyolefin containing an acid-modified polyolefin resin (A) having an unsaturated carboxylic acid component of 0.5 to 20% by mass and an alkali metal hydroxide (B) as a basic compound. Polyolefin resin aqueous dispersion.
(2) The acid-modified polyolefin resin aqueous dispersion according to (1), wherein the alkali metal hydroxide (B) is at least one selected from sodium hydroxide, lithium hydroxide, and potassium hydroxide.
(3) The content of the alkali metal hydroxide (B) is 0.5 to 5.0 times equivalent to the carboxyl group in the acid-modified polyolefin resin (1) or (2) An acid-modified polyolefin resin aqueous dispersion described in 1.
(4) A binder for a secondary battery electrode using the aqueous acid-modified polyolefin resin dispersion according to any one of (1) to (3).
(5) A slurry containing the binder for a secondary battery electrode according to (4).
(6) An electrode for a secondary battery formed using the slurry described in (5).
(7) A positive electrode for a secondary battery according to (6), wherein a compound containing manganese and / or nickel is used as an active material.
(8) A secondary battery using the secondary battery electrode according to (6) or (7).

The aqueous dispersion of the acid-modified polyolefin resin of the present invention is excellent in pH stability and metal ion mixing stability, and is excellent in adhesion to various base materials and chemical resistance (solvent resistance). An adhesive layer can be formed.
Moreover, when the acid-modified polyolefin resin aqueous dispersion of the present invention is used as a binder for a secondary battery electrode, it has excellent adhesion to an active material, a conductive additive, and a metal current collector, and the resulting adhesive layer is electrolyzed. Excellent swelling resistance against liquids. Furthermore, since the acid-modified polyolefin resin aqueous dispersion of the present invention has excellent metal ion mixing stability, when an active material using lithium oxide is used, it has excellent stability without causing aggregates and thickening. An electrode slurry can be obtained, and a good electrode can be formed by using this electrode slurry.

Hereinafter, the present invention will be described in detail.

  The acid-modified polyolefin resin aqueous dispersion of the present invention (hereinafter sometimes abbreviated as an aqueous dispersion) contains an acid-modified polyolefin resin (A) and an alkali metal hydroxide (B).

The polyolefin component of the acid-modified polyolefin resin (A) is not particularly limited, and alkene having 2 to 6 carbon atoms such as propylene, ethylene, isobutylene, 2-butene, 1-butene, 1-pentene, 1-hexene, It may contain diene compounds such as butadiene, isoprene and chloroprene after polymerization and hydrogenated double bonds. When used as a binder for electrodes, it is necessary to prevent oxidation due to high potential at the positive electrode. It is more preferable to use a hydrogenated double bond. Propylene component is particularly excellent in electrolytic solution resistance, and ethylene component and butene component are particularly excellent in flexibility and adhesiveness. Therefore, either propylene component, ethylene component or butene component, or a combination of two or more thereof is contained. Preferably, it contains three types of propylene component, ethylene component, and butene component.

The acid-modified polyolefin resin (A) needs to contain 0.5 to 20% by mass of an unsaturated carboxylic acid component, preferably 0.5 to 10% by mass, The content of 1 to 8% by mass is particularly preferable because the balance between solvent resistance and electrolytic solution resistance is good. When the content of the unsaturated carboxylic acid component is less than 0.5% by mass, it becomes difficult for the acid-modified polyolefin resin (A) to be stably dispersed in an aqueous medium. Good adhesion cannot be obtained due to the low polarity of the film. On the other hand, when the content of the unsaturated carboxylic acid component exceeds 20% by mass, the solvent resistance and the electrolytic solution resistance are lowered.

  Unsaturated carboxylic acid component is introduced by unsaturated carboxylic acid or its anhydride, specifically, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, etc. Besides these, unsaturated dicarboxylic acid half esters, half amides and the like can be mentioned. Of these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferable, and acrylic acid and maleic anhydride are particularly preferable. The unsaturated carboxylic acid component only needs to be copolymerized with the polyolefin resin, and the form thereof is not particularly limited, and examples thereof include random copolymerization, block copolymerization, and graft copolymerization (graft modification). When an acid anhydride is introduced, an acid anhydride structure is formed in which the adjacent carboxyl group is dehydrated and cyclized in the dry state of the resin, but in particular in a medium containing a basic compound, a part of the acid anhydride structure is formed. Or all ring-opened to take the structure of carboxylic acid or its salt

The acid-modified polyolefin resin (A) may contain the following components up to 25% by mass. That is, alkenes with more than 6 carbon atoms such as 1-octene and norbornene, and (meth) acrylic acid esters such as dienes, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, etc. , Maleic acid esters such as dimethyl maleate, diethyl maleate and dibutyl maleate, alkyl vinyl ethers such as (meth) acrylic acid amides, methyl vinyl ether and ethyl vinyl ether, vinyl formate, vinyl acetate, vinyl propionate, Vinyl esters such as vinyl pivalate and vinyl versatate, vinyl alcohol obtained by saponifying vinyl esters with basic compounds, 2-hydroxyethyl acrylate, glycidyl (meth) acrylate, (meth) acrylonitrile, butadiene, etc. The Emissions compounds, vinyl halides, halogenated fluoride acids, carbon monoxide, and the like sulfur dioxide, or a mixture thereof. When the content exceeds 25% by mass, the solvent resistance and electrolytic solution resistance of the resin are impaired, which is not preferable. These components may be copolymerized with the acid-modified polyolefin resin (A), and the form thereof is not particularly limited, and examples thereof include random copolymerization, block copolymerization, graft copolymerization (graft modification), and the like. .

Further, the acid-modified polyolefin resin (A) may be used after being hydrophilized. Examples of the hydrophilic treatment include a hydroxyl group modification treatment, a sulfonation treatment, a fluorine gas treatment, a graft polymerization treatment, or a discharge treatment, and one or more of these hydrophilic treatments can be performed. By performing hydrophilic treatment on the acid-modified polyolefin resin (A), the electrode using the aqueous resin dispersion of the acid-modified polyolefin resin (A) as the binder for the secondary battery electrode is excellent in electrolyte penetration, and the battery In addition to improving the productivity when manufacturing the electrode, the affinity between the electrode and the electrolyte can be improved, and stable cycle characteristics can be obtained.

Examples of the hydroxyl group modification treatment include a heat treatment in the presence of a peroxide having a hydroperoxy group.
Further, as the sulfonation treatment, for example, a treatment immersed in a solution such as fuming sulfuric acid, sulfuric acid, chlorosulfuric acid, or sulfuryl chloride, a treatment contacting with SO ₃ gas, or in the presence of SO gas and / or SO ₂ gas The process which makes discharge act can be mentioned. Among these, the sulfonation treatment with fuming sulfuric acid is preferable because it has high reactivity and can be sulfonated relatively easily. In this case, sulfonic acid groups are mainly introduced.

The molecular weight of the acid-modified polyolefin resin (A) is not particularly limited, but the mass average molecular weight is preferably 10,000 or more, more preferably 10,000 to 150,000, still more preferably 12,000 to 120,000, and 15,000. 100000 is particularly preferable, and 20000 to 90000 is most preferable. When the mass average molecular weight is less than 10,000, the electrodes become brittle, and the adhesiveness between the active materials and the adhesiveness between the active material and the current collector may be reduced. When the mass average molecular weight exceeds 150,000, it tends to be difficult to make the resin water-based.
In addition, the weight average molecular weight of resin can be calculated | required on the basis of polystyrene resin using a gel permeation chromatography (GPC).

Next, the alkali metal hydroxide (B) will be described.

By using the alkali metal hydroxide (B), some or all of the carboxyl groups of the acid-modified polyolefin resin (A) are neutralized, and aggregation between the fine particles is caused by the electric repulsion between the anions generated by the neutralization. It is prevented and stability is imparted to the aqueous dispersion. Moreover, the destabilization of the aqueous dispersion by metal ion mixing can be suppressed because the counter ion of a carboxyl anion becomes an alkali metal ion. As the alkali metal hydroxide, sodium hydroxide, lithium hydroxide, or potassium hydroxide is preferable, and the acid-modified polyolefin resin aqueous dispersion has a small particle size, and a good dispersion free of aggregates can be obtained. Lithium hydroxide is particularly preferable because of excellent mixing stability.

In addition to the alkali metal hydroxide (B) added to the aqueous dispersion, ammonia or various organic amine compounds may be used in combination. The boiling point of the organic amine compound is preferably 250 ° C. or lower. When it exceeds 250 ° C., it becomes difficult to disperse the organic amine compound from the resin film by drying, and the water resistance of the film may deteriorate due to the remaining organic amine compound.

When ammonia or an organic amine is used, the amount added is preferably less than 100 parts by weight, more preferably 80 parts by weight or less, and more preferably 50 parts by weight with respect to 100 parts by weight of the alkali metal hydroxide to be added. It is particularly preferred that the amount is not more than parts. If it exceeds 100 parts by mass, the drying time at the time of film formation may be prolonged, or the resin aqueous dispersion may be colored, which is not preferable.

Specific examples of the organic amine compound include triethylamine, N, N-dimethylethanolamine, aminoethanolamine, N-methyl-N, N-diethanolamine, isopropylamine, iminobispropylamine, ethylamine, diethylamine, and 3-ethoxypropylamine. , 3-diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, methyliminobispropylamine, 3-methoxypropylamine, monoethanolamine, diethanolamine, triethanolamine, morpholine, N-methylmorpholine, N- Examples thereof include ethyl morpholine.

The addition amount of the alkali metal hydroxide (B) is preferably 0.5 to 5.0 times equivalent to the carboxyl group in the acid-modified polyolefin resin (A), and the acid-modified polyolefin resin having a small particle size. An aqueous dispersion is obtained, and the adhesiveness and electrode resistance value are improved. When the blending amount of the alkali metal hydroxide (B) is less than 0.5 times equivalent, the addition effect of the alkali metal hydroxide (B) is not recognized, while the blending amount exceeds 5.0 times equivalent. In this case, the dispersibility is lowered and an undispersed product is generated, so the stability of the aqueous dispersion may be lowered.

Next, the aqueous dispersion of the present invention will be described.

The aqueous dispersion of the present invention can be obtained by making the acid-modified polyolefin resin (A) and the alkali metal hydroxide (B) aqueous by the method described later.

The resin content in the aqueous dispersion of the present invention can be appropriately selected depending on the film forming conditions, the desired thickness and performance of the resin layer, and is not particularly limited. However, the viscosity of the aqueous resin dispersion is appropriately maintained. And 1-50 mass% is preferable at the point which expresses favorable coating-film formation ability, and 5-40 mass% is especially preferable.

The aqueous dispersion of the present invention preferably contains no surfactant such as an emulsifier or a compound having a protective colloid effect, but contains about 1 part by mass or less of the surfactant with respect to 100 parts by mass of the acid-modified polyolefin resin. You can do it. The aqueous dispersion of the present invention can provide a stable aqueous dispersion having a small particle size without using these surfactants. Since surfactants are generally non-volatile, they remain in the resin film even after the film is formed, and have the effect of plasticizing the film, resulting in a decrease in adhesiveness and chemical resistance (solvent resistance). It becomes a problem. Further, when used as a binder for a secondary battery electrode described later, the surfactant moves to the interface of the active material or the electrode, and there is a problem that the adhesiveness is deteriorated or the electrolytic solution resistance is deteriorated. Moreover, since solvent resistance falls, there exists a problem that it cannot use with solvent-type electrolyte solution, and that it is easy to generate | occur | produce an aggregate by the strong shear at the time of battery slurry preparation.

Examples of the surfactant used in the present invention include emulsifiers, compounds having a protective colloid effect, modified waxes, high acid value acid-modified compounds, water-soluble polymers, and the like. Examples of the emulsifier include a cationic emulsifier, an anionic emulsifier, a nonionic emulsifier, and an amphoteric emulsifier. In addition to those generally used for emulsion polymerization, surfactants are also included. For example, anionic emulsifiers include higher alcohol sulfates, higher alkyl sulfonates, higher carboxylates, alkyl benzene sulfonates, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfosuccinates. Nonionic emulsifiers include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide-propylene oxide. Compounds having a polyoxyethylene structure such as copolymers and sorbitan derivatives such as polyoxyethylene sorbitan fatty acid esters And examples of the amphoteric emulsifiers, lauryl betaine, lauryl dimethyl amine oxide, and the like.

You may add the aqueous dispersion of another polymer to the aqueous dispersion of this invention. The aqueous dispersion of the other polymer is not particularly limited. For example, polyvinyl chloride, polyvinylidene chloride, styrene-maleic acid resin, styrene- (meth) acrylic resin, styrene-butadiene resin, butadiene resin, acrylonitrile. -Aqueous dispersions such as butadiene resin, poly (meth) acrylonitrile resin, (meth) acrylamide resin, polyester resin, modified nylon resin, urethane resin, acrylic resin, phenol resin, silicone resin, and epoxy resin. You may use these in mixture of 2 or more types. The amount of the aqueous dispersion added to the other polymer is not particularly limited, but is preferably used in the range of 1 to 80 parts by mass of the solid content of the other polymer with respect to 100 parts by mass of the acid-modified polyolefin resin (A). The

In order to further improve various coating film performances such as water resistance and solvent resistance, the crosslinking agent is 0.01 to 100 parts by mass, preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin (A). 60 parts by mass can be added. As the crosslinking agent, a crosslinking agent having self-crosslinking property, a compound having a plurality of functional groups that react with a carboxyl group in the molecule, a metal complex having a polyvalent coordination site, etc. can be used. Of these, isocyanate compounds , Melamine compounds, urea compounds, epoxy compounds, carbodiimide compounds, oxazoline group-containing compounds, zirconium salt compounds, silane coupling agents and the like are preferable. Moreover, you may use combining these crosslinking agents.

In the aqueous dispersion of the present invention, various agents such as a leveling agent, an antifoaming agent, an anti-waxing agent, an antistatic agent, a pigment dispersant, an ultraviolet absorber, titanium oxide, zinc white, carbon black, etc. Other pigments or dyes may be added. In addition, organic or inorganic compounds other than those described above can be added as long as the stability of the aqueous dispersion is not impaired.

In the present invention, when the acid-modified polyolefin resin (A) is made aqueous, it is preferable to add an organic solvent when making the aqueous solution. The addition amount of the organic solvent used in the aqueous treatment is preferably 1 to 40 parts by mass, more preferably 2 to 30 parts by mass, and particularly preferably 3 to 20 parts by mass with respect to 100 parts by mass of the aqueous resin dispersion. . When the addition amount of the organic solvent exceeds 20 parts by mass, it is preferable to reduce the content of the organic solvent by stripping described later. When the amount of the organic solvent used in making the aqueous solution exceeds 40 parts by mass, problems such as a longer stripping time occur. When the amount of the organic solvent added is less than 1 part by mass, it becomes difficult to make the resin water-based, or it is necessary to raise the temperature in the system in order to make the resin water-soluble, and the main chain of the resin is decomposed. May reduce the molecular weight.

The organic solvent can be removed (stripped) partly or entirely outside the system by heating the aqueous dispersion under normal pressure or reduced pressure while stirring and distilling off the organic solvent. Is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, still more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less with respect to 100 parts by mass of the aqueous dispersion. When the content of the organic solvent exceeds 30 parts by mass, not only the original purpose of making the aqueous solution is lost, but also the stability of the aqueous dispersion may be lowered. Although the content of the organic solvent can be less than 0.01 parts by mass (the detection limit of the analytical instrument used for the measurement of the present invention), the degree of decompression of the apparatus for distilling off the solvent can be increased, or the operation time can be increased. In view of productivity, the content of the organic solvent may be 0.01% by mass or more.

As the organic solvent used in the present invention, those having a solubility in water at 20 ° C. of 5 g / L or more are preferably used, and more preferably 10 g / L or more. Those having a solubility of less than 5 g / L are not preferred because of problems in stability such as phase separation. Especially, a thing with a boiling point of 30-250 degreeC is preferable, and a 50-200 degreeC thing is especially preferable. When the boiling point of the organic solvent is less than 30 ° C., the ratio of volatilization when the resin is made aqueous increases, and the aqueous formation may not proceed completely. An organic solvent having a boiling point exceeding 250 ° C. is difficult to scatter from the adhesive layer by drying, and the water resistance of the adhesive layer may be deteriorated.

Specific examples of the organic solvent used in the present invention include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl. Alcohols such as alcohol, tert-amyl alcohol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol and cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, cyclohexanone and isophorone , Ethers such as tetrahydrofuran, dioxane, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, acetic acid-3-meth Cibutyl, methyl propionate, ethyl propionate, diethyl carbonate, dimethyl carbonate, etc., ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate , Glycol derivatives such as diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol methyl ether acetate Furthermore, 3-methoxy-3-methylbutanol, 3-methoxybutanol, acetonitrile, dimethylformamide, dimethylacetamide, diacetone alcohol, ethyl acetoacetate and the like can be mentioned. Among the above organic solvents, the resin can be made aqueous. From the point that it is easy to remove the organic solvent from the resin aqueous medium, ethanol, n-propanol, isopropanol, n-butanol, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, Ethylene glycol monobutyl ether is preferred. These organic solvents may be used in combination of two or more.

The method for obtaining the aqueous dispersion of the present invention is not particularly limited. For example, (1) the acid-modified polyolefin resin (A) is dissolved in an organic solvent and then emulsified by adding water and an alkali metal hydroxide (B). (2) A method in which an acid-modified polyolefin resin (A), an alkali metal hydroxide (B), water, preferably an organic solvent described later is charged in a container that can be sealed, and emulsified by heating, stirring, and the like. .

Any container may be used as long as it is equipped with a tank into which a liquid can be charged and can appropriately stir the mixture of the aqueous medium and the resin powder or granular material charged into the tank. As such an apparatus, an apparatus widely known to those skilled in the art as a solid / liquid stirring apparatus or an emulsifier can be used, and an apparatus capable of pressurization of 0.1 MPa or more is preferably used. The stirring method and the rotation speed of stirring are not particularly limited.

The number average particle size and volume average particle size of the aqueous dispersion of the present invention are, when used as a binder for a secondary battery described later, a viewpoint of improving the dispersibility of an active material, a conductive additive, active materials, or active materials. From the viewpoint of tightly binding the conductive assistant and the internal resistance of the electrode and from the viewpoint of the storage stability of the binder for the secondary battery, it is preferably 0.001 to 1 μm. Furthermore, 0.001-0.4 micrometer is preferable and 0.001-0.03 micrometer is especially preferable. When the particle diameter exceeds 1 μm, the resistance value increases when binding the active material or the conductive additive, the low-temperature film-forming property is remarkably deteriorated, or the storage stability of the aqueous dispersion is lowered. By using the resin having the composition as described above, an aqueous dispersion having a small particle diameter can be obtained. The number average particle size and volume average particle size of the aqueous dispersion are measured by a dynamic light scattering method generally used for measuring the particle size of the fine particles.

The aqueous dispersion of an acid-modified polyolefin resin of the present invention is suitable for each use of a primer, an adhesive, and a paint.

Since the aqueous dispersion of the present invention is excellent in film forming ability, it can be formed by a known film forming method. For example, uniformly coat the surface of various substrates by gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, brush coating method, etc. A uniform resin film can be formed on the surface of various substrates by setting it near room temperature and then subjecting it to drying or heat treatment for drying and baking. As a heating device at this time, a normal hot air circulation type oven, an infrared heater, or the like may be used. The heating temperature and the heating time are appropriately selected depending on the characteristics of the base material, the type of additive, the blending amount, etc., but are usually 30 ° C. to the melting point of the base material, preferably 60 ° C. to the melting point of the base material, The drying time is about 1 second to 5 minutes. In addition, what is necessary is just to select suitably the conditions that reaction of resin and a crosslinking agent fully advances when a crosslinking agent is added. You may perform an aging process further as needed.

The coating amount of the aqueous dispersion of the present invention is appropriately selected depending on the application, but it is excellent in uniformity if it is in the range of 0.001 to 100 g / m ² as the coating amount after drying. A resin coating is obtained. When used as an adhesive is preferably 1 to 100 g / ^{m 2} The coating amount after drying, the economic and more preferably 1 to 30 g / ^{m 2.} When used as a primer, a high coating amount is not necessarily required, and a sufficient effect is obtained at about 0.001 to 5 g / m ² . Economically, 0.005 to 1 g / m ² is more preferable.

The aqueous dispersion of the present invention can be applied to various substrates, and the aqueous medium can be removed to obtain a laminate. Applicable substrates include paper, synthetic paper, thermoplastic resin, steel plate, aluminum foil, wood, woven fabric, knitted fabric, non-woven fabric, gypsum board, wood board and the like.

Examples of the thermoplastic resin include polyethylene resins such as polyethylene terephthalate, polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, polyhydroxycarboxylic acids such as polyglycolic acid and polylactic acid, Biodegradable resins typified by aliphatic polyester resins such as poly (ethylene succinate) and poly (butylene succinate), polyamide resins such as nylon 6, nylon 66 and nylon 46, PP, polyethylene and ethylene-vinyl acetate Examples thereof include polyolefin resins such as polymers and ionomers, rubber resins, polyimide resins, polyarylate resins, and mixtures thereof. Polyester resins, polyamide resins, polyethylene, ethylene-vinyl Le acetate copolymer, ionomer, PP, rubber-based resin is preferable, PP, use of the rubber-based resin is particularly preferred. Examples of the rubber-based resin include polyolefin rubber (polyolefin elastomer), polybutadiene, polychloroprene, natural rubber, styrene-acrylonitrile rubber, and styrene-butadiene rubber. Examples of the polyolefin rubber (polyolefin elastomer) include ethylene-propylene copolymers, ethylene-propylene-butene copolymers, propylene-butene copolymers, and modified products thereof (acid-modified, chlorinated products).

Examples of the form of the thermoplastic resin include a molded body and a film (including a sheet). The film may be an unstretched film or a stretched film, and the production method is not particularly limited. Moreover, the laminated body which consists of a some layer may be sufficient as a film. Although the thickness is not particularly limited, it is usually in the range of 1 to 500 μm. Furthermore, you may perform what is called in-line coating which extends | stretches a film, after apply | coating the resin aqueous dispersion to an unstretched film.

The thermoplastic resin film is usually subjected to a corona treatment in order to improve wettability and adhesiveness. The coating film obtained from the aqueous resin dispersion of the present invention is a non-corona coating of the thermoplastic resin film. It has excellent adhesion to the treated surface, especially the non-corona treated surface of PP, which is a material that is difficult to adhere. Accordingly, the corona treatment process can be omitted, which is economically advantageous.

Silica, alumina or the like may be deposited on the thermoplastic resin film, or a gas barrier coat layer such as an oxygen gas barrier layer may be laminated.

When used as an adhesive, the aqueous dispersion of the present invention is used as it is, or a compound such as the above-described crosslinking agent, tackifier component, aqueous dispersion of other polymers, etc. is blended to obtain an adhesive. As a so-called heat seal adhesive, an aqueous dispersion of the present invention is applied to a film or the like and dried to form an adhesive layer, and then another substrate is placed on the adhesive layer and heated to adhere. However, when paper or cloth is used as the base material, an aqueous resin dispersion is applied to the base material, and another base material is placed in a wet state, followed by natural drying or heat drying. Can also be adhered.

When used as a primer, the aqueous dispersion of the present invention is applied to the substrate surface and then dried to form a coating film. Other materials (ink, film, etc.) can be easily laminated on the coating film thus obtained.

When used as a paint, a pigment or dye is blended with the aqueous dispersion of the present invention to obtain a paint.

Furthermore, since the aqueous dispersion of the present invention is excellent in adhesion to a substrate and resistance to electrolytic solution, and further in excellent metal ion mixing stability, it is stable when an active material using lithium oxide is used. Since it is possible to obtain an agglomerate having excellent properties and a slurry that does not cause thickening and to form a good electrode, it is suitably used as a binder for secondary battery electrodes.

Lithium ion batteries generally use an electrode made through a separator between a positive electrode and a negative electrode together with an electrolyte (in the case of a lithium ion polymer battery, a gel or all solid electrolyte instead of a liquid electrolyte). It has a structure housed inside. An electrode for a lithium ion battery is formed by layering an active material and, if necessary, a conductive assistant mainly made of a carbon material on a metal current collector such as an aluminum foil or a copper foil using a binder. is there.

Examples of the separator include polyethylene nonwoven fabric, polypropylene nonwoven fabric, polyamide nonwoven fabric, and glass fiber. As the electrolytic solution, a supporting electrolytic salt such as lithium hexafluorophosphate and lithium perchlorate was added to a mixed solvent obtained by mixing one kind or two or more kinds of nonaqueous solvents such as ethylene carbonate, diethyl carbonate, and propylene carbonate. Things.

Instead of the separator, a solid electrolyte or a gel electrolyte may be used. Examples of the solid electrolyte and gel electrolyte include tetraethylammonium tetrafluoroborate, triethylmonomethylammonium tetrafluoroborate, tetraethylammonium hexafluorophosphate, ionic liquid, aqueous sulfuric acid solution, and aqueous potassium hydroxide solution. The solvent for dissolving the electrolyte (electrolytic solution solvent) is not particularly limited as long as it is generally used as an electrolytic solution solvent. Specific examples include carbonates such as propylene carbonate, ethylene carbonate and butylene carbonate; lactones such as γ-butyrolactone; sulfolanes; nitriles such as acetonitrile; ionic liquids and the like. These can be used alone or as a mixed solvent of two or more.

The secondary battery electrode can be formed by applying and drying a slurry produced using the secondary battery electrode binder of the present invention on a current collector. The current collector may be any material having conductivity, and examples thereof include metals such as aluminum, nickel, and copper. Although there is no restriction | limiting in particular in the thickness of an electrical power collector, Usually, a 5-50 micrometers thin film is used.

Examples of a method for applying the slurry on the current collector include a method using a doctor blade. Examples of a method for removing the aqueous medium after applying the slurry include a method of drying at 60 to 150 ° C., preferably 70 to 130 ° C. for 5 to 120 minutes. Furthermore, for example, you may dry under reduced pressure at 120 degreeC for 12 hours. The thickness of the electrode after coating and drying is preferably 30 to 150 μm from the viewpoint of electrode productivity and battery characteristics. In order to control the thickness and density of the electrode, it is preferable to press, for example, with a roll press.

The slurry can be prepared by incorporating the secondary battery electrode binder of the present invention, the electrode active material, and, if necessary, a conductive additive. The active material is preferably a material that can reversibly release and occlude lithium ions and has high electronic conductivity. Examples of the positive electrode active material include transition metal oxides such as lithium cobaltate, lithium nickelate, and lithium manganate. Although a thing is mentioned, it is not limited to these. Examples of the negative electrode active material include, but are not limited to, carbon materials such as graphite and lithium titanate.

When lithium oxide such as lithium nickelate and lithium manganate is used as the positive electrode active material and lithium titanate is used as the negative electrode active material, it is used after adjusting the pH by adding an acid component. The acid component to be used is not particularly limited. For example, organic acids such as acetic acid, sulfuric acid, oxalic acid and formic acid, and inorganic acids such as carbon dioxide and hydrochloric acid are used.

When the acid-modified polyolefin resin dispersion of the present invention is used as a binder for a secondary battery electrode, it has excellent metal ion mixing stability, so that excellent slurry stability can be achieved even when the above lithium oxide is used as an active material. The binder for secondary battery electrodes which has the property can be provided.

As the conductive assistant, a carbon material, a metal, or a compound thereof can be used. Examples of the carbon material include ketjen black, acetylene black, furnace black, graphite, and carbon fiber. Examples of the metal or a compound thereof include nickel, cobalt, titanium, cobalt oxide, and titanium oxide. However, it is not limited to these.

The content of the acid-modified polyolefin resin (A) in the secondary battery electrode slurry is 0.01 to 8% by mass with respect to the total mass of the acid-modified polyolefin resin (A), the electrode active material and the conductive additive. Preferably there is. When content of resin (B) exceeds 8 mass%, there exists a tendency for the electrical resistance value in the electrode obtained to become high. On the other hand, if it is less than 0.01% by mass, sufficient adhesion between the active material, the conductive additive and the current collector cannot be obtained.

In the present invention, the conditions and method for producing the slurry for the secondary battery electrode are not particularly limited, and the binder for the secondary battery electrode, the active material for the electrode, and the conductive additive are mixed at room temperature or at an appropriately controlled temperature. Then, a mechanical dispersion process, a method of ultrasonic dispersion process, and the like can be mentioned. In this case, the mixing order is not particularly limited.

And it is preferable that the slurry for secondary battery electrodes of this invention adds a water-soluble polymer as another polymer in addition to an aqueous dispersion. Specific examples of the water-soluble polymer include cellulosic polymers such as carboxymethylcellulose, methylcellulose, and hydroxypropylcellulose, polyacrylates such as sodium polyacrylate, polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, acrylic acid, and acrylate. Examples include vinyl alcohol copolymers, maleic anhydride or copolymers of maleic acid or fumaric acid and vinyl alcohol, modified polyvinyl alcohol, and modified polyacrylic acid. Among these, cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, and hydroxymethyl cellulose are preferable from the viewpoint of the stability of the electrode slurry. These water-soluble polymers improve the wettability between the current collector, the active material, and the conductive material, and play a role as a so-called thickener. As a result, the adhesion between the active material and the conductive material, and between these and the metal current collector is improved, and the resulting battery has excellent cycle characteristics.

As a compounding quantity of the said water-soluble polymer, 0.01-5 mass parts is preferable with respect to a total of 100 mass parts of acid-modified polyolefin resin (A), a conductive support agent, and the active material for electrodes, More preferably, it is 0.01. -3 mass parts, More preferably, it is 0.01-1.5 mass parts. If the blending amount is less than 0.01 parts by mass, the stability and coating properties of the secondary battery electrode slurry may be deteriorated. On the other hand, if it exceeds 3 parts by mass, the battery characteristics may be deteriorated. is there.

By using the aqueous dispersion of the present invention, a secondary battery electrode binder having excellent electrode slurry stability due to excellent adhesion, addition of a small amount of electrolyte, and excellent stability of mixed metal ions when added in small amounts. Can be provided. Moreover, it can be applied to both positive and negative electrodes, and by using this secondary battery electrode binder, it is possible to provide a secondary battery electrode and a secondary battery that are particularly excellent in cycle characteristics.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.
Various characteristics were measured or evaluated by the following methods.

1. Resin characteristics (1) Content of acid-modified component in resin The acid value and hydroxyl value of the resin were measured according to the method described in JIS K0070, and the content of the acid-modified component was determined from the value.
(2) Constitution of resin It was determined in orthodichlorobenzene (d ₄ ) using ¹ H-NMR analysis (manufactured by Varian, 300 MHz) at 120 ° C.

2. Acid Modified Polyolefin Resin Aqueous Dispersion Characteristics (3) Solid Content Concentration of Acid Modified Polyolefin Resin Aqueous Dispersion An appropriate amount of acid modified polyolefin resin aqueous dispersion is weighed, and the mass of the residue (solid content) is constant at 150 ° C. It heated until it reached | attained and calculated | required solid content concentration.
(4) Average particle diameter of acid-modified polyolefin resin aqueous dispersion The number average particle diameter was determined using a Microtrac particle size distribution analyzer UPA150 (MODEL No. 9340, dynamic light scattering method) manufactured by Nikkiso Co., Ltd. Here, the refractive index of the resin used for calculating the particle diameter was set to 1.50.
(5) Content of organic solvent in acid-modified polyolefin resin aqueous dispersion Gas chromatograph GC-8A manufactured by Shimadzu Corporation [using FID detector, carrier gas: nitrogen, column packing material (manufactured by GL Sciences): PEG-HT ( 5%)-Uniport HP (60/80 mesh), column size: diameter 3 mm × 3 m, sample charging temperature (injection temperature): 150 ° C., column temperature: 60 ° C., internal standard substance: n-butanol A modified polyolefin resin aqueous dispersion or an acid-modified polyolefin resin aqueous dispersion diluted with water was directly charged into the apparatus, and the content of the organic solvent was determined. The detection limit was 0.01% by mass.
(6) pH stability 1 ml of triethylamine was gradually added dropwise to 5 ml of an aqueous dispersion, and the pH stability in the basic region was evaluated based on the presence or absence of aggregates. The higher the pH value at which aggregates were generated, the better the pH stability in the basic region, and no aggregates were formed even when all triethylamine was added dropwise (indicated as “None” in the table). ) Indicates the highest stability.
(7) Metal ion mixing stability 25 ml of an aqueous dispersion was dropped into 5 ml of an aqueous lithium hydroxide solution (5% by mass) and mixed with lithium ions of an acid-modified polyolefin resin aqueous dispersion with or without the occurrence of aggregates. Stability was evaluated. ○: No aggregate is generated, ×: Aggregate is generated

3. Adhesive layer properties (8) The adhesive aqueous dispersion was applied to the aluminum surface of an aluminum / PET film (base material layer 1) so that the thickness of the adhesive layer after drying was 3 μm and dried at 120 ° C. for 60 seconds. Thereafter, the laminate was bonded to the aluminum surface of the aluminum / PET film (base material layer 2) and pressed at 120 ° C. for 10 seconds with a heat press (sealing pressure 0.3 MPa) to obtain a laminate. This laminate was cut out with a width of 15 mm, and an aluminum-aluminum layer was peeled off at 180 ° using a tensile tester (Intesco precision universal material tester type 2020 manufactured by Intesco) under an atmosphere of 25 ° C. The adhesive strength of the adhesive layer characteristic was evaluated by measuring the peel strength at n = 5.
(9) The aqueous dispersion was coated on the corona surface of the solvent-resistant PET film using a Meyer bar so that the thickness of the coating film after drying was 3 μm, and then dried at 120 ° C. for 60 seconds. The obtained coating film was immersed in methyl ethyl ketone at 40 ° C. for 24 hours, the surface was lightly wiped, the weight and thickness were measured, and the weight change rate and thickness change rate were calculated.
Weight change rate [%] = ((weight after immersion [g] −weight before immersion [g]) / weight before immersion [g]) × 100
Thickness change rate [%] = ((Thickness after immersion [μm] −Thickness before immersion [μm]) / Thickness before immersion [μm]) × 100

4). Electrode characteristics (10) Electrode adhesiveness A measurement sample having a width of 2.5 cm and a length of 10 cm was cut out from an electrode formed on an aluminum foil, and the aluminum side was bonded to a steel plate having a sufficient thickness with a double-sided tape. Cellophane tape (manufactured by Nichiban Co., CT-18, 18 mm width) was applied to the electrode layer side of the test sample, and the stress was measured when the test sample was peeled off at a rate of 50 mm / min in the direction of 180 ° from one side. The measurement was carried out three times for each sample, and the average value was taken as the peel strength to evaluate the electrode adhesion.
(11) The electrolyte-resistant acid-modified polyolefin resin aqueous dispersion was dried at 80 ° C., 100 ° C., and 120 ° C. by gradually raising the temperature for 2 hours, thereby preparing a 500 mg dried sheet. Immerse the dried product in an electrolytic solution (ethylene carbonate / diethyl carbonate / methyl ethyl carbonate (1/1/1 weight ratio)), store at 60 ° C. for 2 weeks, remove from the electrolytic solution, and then gently wipe the electrolytic solution on the surface. The weight and thickness were measured, and the weight change rate and thickness change rate were calculated.
Weight change rate [%] = ((weight after immersion in electrolytic solution [g] −weight before immersion in electrolytic solution [g]) / weight before immersion in electrolytic solution [g]) × 100
Thickness change rate [%] = ((Thickness after immersion in electrolytic solution [μm] −Thickness before immersion in electrolytic solution [μm]) / Thickness before immersion in electrolytic solution [μm]) × 100
(12) Slurry stability Immediately after the electrode slurry described later was prepared, the viscosity after storage for 150 hours was measured using a B-type viscometer manufactured by Brookfield. The viscosity immediately after the production was taken as 100%, stored at 25 ° C. for one week, and the change in viscosity after storage was calculated. The measurement was performed at 25 ° C.
Viscosity change rate [%] = (viscosity after storage [mPa · s]) / viscosity immediately after production [mPa · s]) × 100
(13) Electrode resistivity A simulated electrode was obtained in the same manner as in “Manufacture of secondary battery electrode” described later except that an electrode slurry described later was applied to a glass plate. The volume resistivity of the simulated electrode was measured with a Loresta GP (manufactured by Dia Instruments). It shows that internal resistance is so low that the volume resistivity of a simulation electrode is low. That is, it shows that electric capacity is large and battery characteristics are good.

5. Battery characteristics (14) Cycle characteristics Examples 12 to 22 and Comparative Examples 11 to 18 use coin-type batteries prepared by combining a secondary battery positive electrode and a graphite electrode, and Examples 23 and 24, Comparative Example 19, No. 20 performed a charge / discharge test using a secondary battery negative electrode and metallic lithium. The cycle characteristics were evaluated by repeatedly performing 0.75C-2.5V constant current discharge after 0.75C-4.0V constant current constant voltage charging in a 50 ° C environment. The initial capacity was set to 100%, the battery capacity after 500 cycles was determined, and the maintenance rate was calculated.

Reference Example 1 Production of Acid-Modified Polyolefin Resin “A-1” Propylene-butene-ethylene terpolymer (manufactured by Huls Japan, Bestplast 708, propylene / butene / ethylene = 64.8 / 23.9 /11.3 mass%) After heating and melting 280 g in a four-necked flask equipped with a stirrer, a condenser tube and a dropping funnel in a nitrogen atmosphere, the system temperature was kept at 165 ° C., and the mixture was unsaturated under stirring. A solution of 32.0 g of maleic anhydride as a carboxylic acid and a solution of 6.0 g of dicumyl peroxide as a radical generator in 20 g of heptane were added over 1 hour, followed by reaction for 1 hour. After completion of the reaction, the obtained reaction product was put into a large amount of acetone to precipitate a resin. The resin was further washed several times with acetone to remove unreacted maleic anhydride, and then dried under reduced pressure in a vacuum dryer to obtain an acid-modified polyolefin resin “A-1”. The properties of the obtained resin are shown in Table 1.

Reference Example 2 Production of Acid-Modified Polyolefin Resin “A-2” Reference was made except that 76.0 g of maleic anhydride was used as the unsaturated carboxylic acid, and a solution of 20 g of heptane in 14.3 g of dicumyl peroxide was used as the radical generator. In the same manner as in Example 1, acid-modified polyolefin resin “A-2” was obtained. The properties of the obtained resin are shown in Table 1.

Reference Example 3 Production of Acid-Modified Polyolefin Resin “H-1” Reference was made except that 1.5 g of maleic anhydride was used as the unsaturated carboxylic acid and 20 g of heptane in 0.3 g of dicumyl peroxide was used as the radical generator. In the same manner as in Example 1, acid-modified polyolefin resin “H-1” was obtained. The properties of the obtained resin are shown in Table 1.

Reference Example 4 Production of Acid-Modified Polyolefin Resin “H-2” Reference was made except that 53.3 g of maleic anhydride was used as the unsaturated carboxylic acid, and 20 g of heptane in 10.0 g of dicumyl peroxide was used as the radical generator. In the same manner as in Example 1, acid-modified polyolefin resin “H-2” was obtained. The properties of the obtained resin are shown in Table 1.

Example 1
Using a stirrer equipped with a heat-resistant 1 L glass container with a heater, 100.0 g of “A-1” as acid-modified polyolefin resin (A), 75.0 g of n-propanol (manufactured by Wako Pure Chemical Industries, Ltd.), As alkali metal hydroxide (B), 2.7 g of lithium hydroxide monohydrate (manufactured by Wako Pure Chemical Industries, Ltd., 0.5 times equivalent to the carboxyl group in “A-1”) is distilled water of 325 g. When the aqueous solution dissolved in the solution was charged into a glass container and stirred at a rotation speed of 300 rpm, no resin precipitation was observed at the bottom of the container, confirming that it was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 120 ° C. and further stirred for 60 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) Further, the solvent in the aqueous dispersion was removed with a rotary evaporator, and water was added so that the solid content was 25% to obtain a milky white aqueous dispersion “E-1”.
(Examples 2 and 3)
In the same manner as in Example 1, except that the amount of lithium hydroxide monohydrate was changed to 1.0 and 2.5 equivalents of the carboxyl group in "A-1," acid-modified polyolefin Resin aqueous dispersions “E-2” and “E-3” were obtained.
(Examples 4 to 6)
The acid-modified polyolefin resin (A) is changed to “A-2”, and the amount of lithium hydroxide monohydrate is 1.0, 1.5, 5, respectively with respect to the carboxyl group in “A-2”. Acid-modified polyolefin resin aqueous dispersions “E-4 to E-6” were obtained in the same manner as in Example 1 except that the amount was changed to 0 times equivalent.
(Example 7)
The acid-modified polyolefin resin (A) is changed to “A-2”, the basic compound is sodium hydroxide, and the amount is 1.0 equivalent to the carboxyl group in “A-2”. In the same manner as in Example 1, an acid-modified polyolefin resin aqueous dispersion “E-7” was obtained.
(Example 8)
Using a stirrer equipped with a 1 L glass container that can be sealed with a heater, 100.0 g of Sanyo Chemical Co., Ltd. Umex 1001 (maleic anhydride-modified polypropylene resin) as an acid-modified polyolefin resin (A), 200 g of tetrahydrofuran, An aqueous solution in which 2.1 g of lithium hydroxide monohydrate (1.0 equivalent equivalent to the carboxyl group in “YUMEX 1001”) was dissolved in 300 g of distilled water as an alkali metal hydroxide (B) in a glass container When the stirring speed was set to 300 rpm and stirring was performed at 300 rpm, no resin precipitation was observed at the bottom of the container, and it was confirmed that the container was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 120 ° C. and further stirred for 60 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) Further, the solvent in the aqueous dispersion was removed with a rotary evaporator, and water was added so that the solid content was 25% to obtain a milky white aqueous dispersion “E-8”.
Example 9
Using a stirrer equipped with a 1 L glass container that can be sealed with a heater, 100.0 g of Arkema Bondine TX-8030, 80 g of isopropanol, alkali metal hydroxide (B) as acid-modified polyolefin resin (A) ), An aqueous solution prepared by dissolving 0.8 g of lithium hydroxide monohydrate (1.0 times equivalent to the carboxyl group in “TX-8030”) in 220 g of distilled water was placed in a glass container, and a stirring blade When the stirring speed was 300 rpm, no resin precipitation was observed at the bottom of the container, and it was confirmed that the container was in a floating state. Therefore, while maintaining this state, the heater was turned on and heated after 10 minutes. Then, the system temperature was kept at 120 ° C. and further stirred for 60 minutes. Then, after cooling to room temperature (about 25 ° C.) while stirring with air rotation at 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) Further, the solvent in the aqueous dispersion was removed with a rotary evaporator, and water was added so that the solid content was 25% to obtain a milky white resin aqueous dispersion “E-9”.
(Example 10)
As a basic compound, in addition to lithium hydroxide monohydrate, 3.9 g of triethylamine (manufactured by Wako Pure Chemical Industries, Ltd., 0.3 times equivalent to the carboxyl group in “A-1”) was added. Except for the above, an acid-modified polyolefin resin aqueous dispersion “E-10” was obtained in the same manner as in Example 1.
(Example 11)
As a basic compound, in addition to lithium hydroxide monohydrate, 3.4 g of dimethylaminoethanol (manufactured by Wako Pure Chemical Industries, Ltd., 0.3 times equivalent to the carboxyl group in “A-1”) was added. Except that, acid-modified polyolefin resin aqueous dispersion “E-11” was obtained in the same manner as in Example 1.
(Comparative Example 1)
The same basic example as in Example 1 except that 26.0 g of triethylamine (2.0 equivalents relative to the carboxyl group in “A-1”) was used instead of lithium hydroxide monohydrate. By the method, an acid-modified polyolefin resin aqueous dispersion “R-1” was obtained.
(Comparative Example 2)
Example 1 except that 22.8 g of dimethylaminoethanol (2.0 equivalents relative to the carboxyl group in “A-1”) was used as the basic compound instead of lithium hydroxide monohydrate. In the same manner, an acid-modified polyolefin resin aqueous dispersion “R-2” was obtained.
(Comparative Example 3)
An acid-modified polyolefin resin aqueous dispersion “R” was prepared in the same manner as in Example 1 except that 1.5 g of a surfactant (New Pole PE-75, manufactured by Sanyo Kasei Co., Ltd.) was used without using a basic compound. -3 "was obtained.
(Comparative Example 4)
The amount of lithium hydroxide monohydrate was changed to 0.3 times the equivalent of the carboxyl group in “A-1”, and further 2.6 g of triethylamine (based on the carboxyl group in “A-1”). An acid-modified polyolefin resin aqueous dispersion “R-4” was obtained in the same manner as in Example 1 except that 0.2 equivalent) was used.
(Comparative Example 5)
In the same manner as in Example 1, except that the amount of lithium hydroxide monohydrate was changed to 0.3 times equivalent to the carboxyl group in “A-1”, the aqueous acid-modified polyolefin resin dispersion “ R-5 "was obtained.
(Comparative Example 6)
The acid-modified polyolefin resin (A) is changed to “A-2”, and the amount of lithium hydroxide monohydrate is changed to 0.3 times equivalent to the carboxyl group in “A-2”. In the same manner as in Example 1, an acid-modified polyolefin resin aqueous dispersion “R-6” was obtained.
(Comparative Example 7)
In the same manner as in Example 1, except that the amount of lithium hydroxide monohydrate was changed to 7.0 equivalents with respect to the carboxyl group in “A-1,” an acid-modified polyolefin resin aqueous dispersion “ R-7 "was obtained.
(Comparative Example 8)
The acid-modified polyolefin resin (A) is changed to “A-2”, and the amount of lithium hydroxide monohydrate is changed to 7.0 times equivalent to the carboxyl group in “A-2”. In the same manner as in Example 1, an acid-modified polyolefin resin aqueous dispersion “R-8” was obtained.
(Comparative Example 9)
Except for changing the acid-modified polyolefin resin (A) to “H-1” and changing the amount of lithium hydroxide monohydrate to 1.0 equivalent to the carboxyl group in “H-1”. In the same manner as in Example 1, an acid-modified polyolefin resin aqueous dispersion “R-9” was obtained.
(Comparative Example 10)
Except for changing the acid-modified polyolefin resin (A) to “H-2” and changing the amount of lithium hydroxide monohydrate to 1.0 equivalent to the carboxyl group in “H-2”. In the same manner as in Example 1, an acid-modified polyolefin resin aqueous dispersion “R-10” was obtained.

About the obtained acid-modified polyolefin resin aqueous dispersions “E-1” to “E-11” and “R-1” to “R-10”, pH stability, metal ion mixing stability, adhesion of adhesive layer characteristics Evaluation of the property and solvent resistance was carried out, and the evaluation results are shown in Tables 2 and 3, respectively.

(Example 12) Production of electrode slurry and electrode for secondary battery positive electrode 96 parts of nickel manganese cobaltate (manufactured by Nippon Chemical Industry Co., Ltd., cell seed NMC111) as a positive electrode active material, and acetylene black (Electrochemical Industry Co., Ltd.) as a conductive material An aqueous solution of 1 part of Denka Black) and 1 part of carboxymethyl cellulose (CMC) (Dell Daigaku Seiyaku Co., Ltd., Cellogen BSH-6) as a thickener was sufficiently kneaded to form a slurry. The slurry was adjusted by adding sulfuric acid as a neutralizing agent so that the pH of the slurry was 9.5, and then 2 parts of “E-1” obtained in Example 1 was added as a secondary battery electrode binder. Then, by sufficiently kneading, an electrode slurry was obtained.
The obtained slurry for electrodes was applied to one side of an aluminum foil having a thickness of 18 μm using a film applicator so that the thickness after drying was about 80 μm, and dried with hot air at 80 ° C. for 30 minutes. In order to remove, it vacuum-dried at 120 degreeC for 15 hours, the active material layer was formed on aluminum foil, and the secondary battery positive electrode was obtained.

(Examples 13-22, Comparative Examples 11-20)
A slurry for an electrode was prepared in the same manner as described in Example 12 except that the type of the binder for the secondary battery electrode and the neutralizing agent were changed to those shown in Table 3, and the obtained electrode slurry was applied. The electrode for secondary batteries obtained by work and drying was obtained.

The slurry stability of the slurry for electrodes obtained in Examples 12 to 22 and Comparative Examples 11 to 20, and the electrode adhesion, the electrolytic solution resistance, and the electrode resistance, which are electrode characteristics of the positive electrode, were evaluated, and further battery characteristics The cycle characteristics were evaluated, and the results are shown in Tables 4 and 5.

As is clear from Table 2, the acid-modified polyolefin resin aqueous dispersions obtained in Examples 1 to 11 were excellent in pH stability, metal ion mixing stability, adhesiveness, and solvent resistance. . Further, as apparent from Table 4, the electrode slurry obtained in Examples 12 to 22 showed excellent slurry stability, and the secondary battery electrode had good adhesion, electrolyte resistance, electrode resistance value. And exhibited excellent cycle characteristics.

On the other hand, as is clear from Tables 3 and 5, R-1 and R-2 obtained in Comparative Examples 1 and 2 are excellent in adhesiveness, but are acid-modified polyolefin resin aqueous dispersions using only organic amines. , PH stability and metal ion mixing stability were poor. Since Comparative Examples 11 and 12 using these aqueous dispersions R-1 and R-2 as binders for secondary battery electrodes use an aqueous dispersion inferior in metal ion mixing stability, the metal from the active material Ion elution was inferior in slurry stability, and aggregates were generated, resulting in poor adhesion and poor battery characteristics.
R-3 obtained in Comparative Example 3 is excellent in metal ion mixing stability, but contains a surfactant. Therefore, the surfactant bleeds out on the surface of the adhesive layer, resulting in poor adhesion and poor solvent resistance. It was enough. Comparative Example 13 using this aqueous dispersion R-3 as a binder for an electrode for a secondary battery was inferior in electrode adhesion and electrolytic solution resistance and inferior in cycle characteristics. Furthermore, the aqueous resin dispersion using a surfactant has a large particle system and inferior electrode resistance.
R-4 obtained in Comparative Example 4 has a small particle system and excellent adhesion by using an organic amine having a small addition amount of lithium hydroxide which is an alkali metal hydroxide (B). Only inferior results in stability and metal ion mixing stability. Comparative Example 14 using this aqueous dispersion R-4 as a binder for an electrode for a secondary battery showed only a result of inferior slurry stability, a decrease in adhesiveness due to the generation of aggregates, and inferior battery characteristics. .
R-5 and 6 obtained in Comparative Examples 5 and 6 have few alkali metal hydroxides (B), it is difficult to produce an acid-modified polyolefin resin aqueous dispersion, and the particle size is large and the adhesiveness is poor. Only showed. Comparative Examples 15 and 16 using these aqueous dispersions R-5 and 6 as binders for electrodes for secondary batteries had poor electrode adhesion and poor cycle characteristics. Moreover, the particle diameter was large and the electrode resistance was also inferior. Furthermore, the slurry stability was poor.
In the aqueous dispersions R-7 and 8 obtained in Comparative Examples 7 and 8, the addition amount of lithium hydroxide which is an alkali metal hydroxide (B) is large, and it is difficult to produce an acid-modified polyolefin resin aqueous dispersion. The particle size was large and the adhesiveness was poor. Comparative Examples 17 and 18 using these aqueous dispersions R-7 and 8 as binders for electrodes for secondary batteries were excellent in slurry stability, but were inferior in electrode resistance, inferior in electrode adhesion and battery characteristics.
R-9 obtained in Comparative Example 9 was excellent in pH stability, metal ion mixing stability, and solvent resistance, but had a low content of unsaturated carboxylic acid component in the resin and was inferior in adhesiveness. Comparative Example 19 using this aqueous dispersion R-9 as an electrode binder for a secondary battery was excellent in slurry stability and electrolytic solution resistance, but was inferior in electrode adhesion and inferior in battery characteristics.
R-10 obtained in Comparative Example 10 was excellent in pH stability, metal ion mixing stability, and adhesiveness, but had a large content of unsaturated carboxylic acid component in the resin and was poor in solvent resistance. Comparative Example 20 using this aqueous dispersion R-10 as a binder for secondary battery electrodes was excellent in slurry stability, but was inferior in electrolytic solution resistance and in battery characteristics.

Claims (8)

An acid-modified polyolefin resin aqueous solution comprising an acid-modified polyolefin resin (A) having an unsaturated carboxylic acid component of 0.5 to 20% by mass and an alkali metal hydroxide (B) as a basic compound. Dispersion. The acid-modified polyolefin resin aqueous dispersion according to claim 1, wherein the alkali metal hydroxide (B) is at least one selected from sodium hydroxide, lithium hydroxide, and potassium hydroxide. The acid-modified acid according to claim 1 or 2, wherein the content of the alkali metal hydroxide (B) is 0.5 to 5.0 times equivalent to a carboxyl group in the acid-modified polyolefin resin. Polyolefin resin aqueous dispersion. The binder for secondary battery electrodes using the acid-modified polyolefin resin aqueous dispersion in any one of Claims 1-3. The slurry containing the binder for secondary battery electrodes of Claim 4. The electrode for secondary batteries formed using the slurry of Claim 5. The secondary battery electrode according to claim 6, wherein a compound containing manganese and / or nickel is used as an active material. A secondary battery using the secondary battery electrode according to claim 6.