Binder composition for electrode, method for producing same, and coating liquid composition for electrode

Abstract

Provided are: a binder composition for an electrode, which is capable of suppressing an increase in the viscosity of a coating liquid for forming an electrode; a method for producing the binder composition; and a coating liquid composition for an electrode, which contains the binder composition. The present invention is a binder composition for electrodes, which contains an aqueous dispersion of a polyurethane resin, and wherein the polyurethane resin has a D50 volume average particle diameter of 0.01 [mu] m or more and 0.05 [mu] m or less and a D90 volume average particle diameter of 0.10 [mu] m or more and 0.15 [mu] m or less.

Description

Technical Field

[0001] The present invention relates to an adhesive composition for an electrode, a coating liquid composition for an electrode, an electrode for a power storage device and a power storage device, and a method for manufacturing the adhesive composition for an electrode. Background Art

[0002] Secondary batteries represented by lithium secondary batteries are indispensable driving power sources in various electronic devices, automobiles, etc., and are widely applied in the industrial world. Currently, research and development on them are also actively carried out. The characteristics of the battery are greatly affected by the types of various materials constituting the battery. Therefore, in recent years, development for making the electrode more high-performance has been actively carried out.

[0003] It is known that such an electrode is formed, for example, by coating a coating liquid containing an electrode active material, an adhesive for an electrode, a dispersant, etc. on a current collector. In particular, the characteristics of an electrode for a battery are determined by the electrode active material and the current collector, but the adhesive also has an important position in determining the electrode characteristics. From this perspective, improving the characteristics of the adhesive is also important. For example, Patent Document 1 discloses a technique for imparting excellent cycle characteristics and rate characteristics to a power storage device by using an electrode using an adhesive composition for an electrode containing a urethane resin.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-097906 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] However, in the case of forming an electrode using a conventional adhesive for an electrode containing a urethane resin, if the solid content concentration of the coating liquid used for forming the electrode becomes high, the viscosity will increase, and thus there are problems of reduced dispersibility and reduced operability.

[0009] The present invention has been completed in view of the above circumstances, and an object thereof is to provide an adhesive composition for an electrode and a method for manufacturing the same, and a coating liquid composition for an electrode containing the adhesive composition, which can suppress an increase in viscosity even when the solid content concentration of the coating liquid used for forming the electrode is increased. In addition, an object of the present invention is to provide an electrode for a power storage device and a power storage device formed using the above coating liquid composition for an electrode.

[0010] Technical Means for Solving the Problem

[0011] The inventors of the present invention have conducted in-depth research repeatedly in order to achieve the above object, and as a result, it has been found that the above object can be achieved by using a polyurethane resin having a specific particle size distribution, and thus the present invention has been completed.

[0012] That is, the present invention includes, for example, the subjects described in the following items.

[0013] Item 1

[0014] An electrode binder composition, wherein,

[0015] it contains a polyurethane resin aqueous dispersion,

[0016] the D50 volume average particle diameter of the above polyurethane resin is 0.01 μm or more and 0.05 μm or less, and the D90 volume average particle diameter is 0.10 μm or more and 0.15 μm or less.

[0017] Item 2

[0018] The electrode binder composition according to the above Item 1, which contains carbon nanotubes.

[0019] Item 3

[0020] The electrode binder composition according to the above Item 2, which contains carboxymethyl cellulose or a salt thereof.

[0021] Item 4

[0022] An electrode coating liquid composition containing the electrode binder composition according to any one of the above Items 1 to 3.

[0023] Item 5

[0024] An electrode for an electric storage device, which contains the solid component of the electrode coating liquid composition according to the above Item 4.

[0025] Item 6

[0026] An electric storage device having the electrode for an electric storage device according to the above Item 5.

[0027] Item 7-1

[0028] A method for manufacturing an electrode binder composition, wherein,

[0029] the above electrode binder composition contains a polyurethane resin aqueous dispersion,

[0030] the above manufacturing method includes a step of preparing a polyurethane resin aqueous dispersion having a D50 volume average particle diameter of 0.01 μm or more and 0.05 μm or less and a D90 volume average particle diameter of 0.10 μm or more and 0.15 μm or less.

[0031] Item 7-2

[0032] A method for manufacturing an adhesive composition for an electrode, wherein,

[0033] is the method for manufacturing the adhesive composition according to any one of the above items 1 to 3,

[0034] This manufacturing method includes a step of preparing a polyurethane resin aqueous dispersion having a D50 volume average particle size of 0.01 μm or more and 0.05 μm or less, and a D90 volume average particle size of 0.10 μm or more and 0.15 μm or less.

[0035] Advantages of the Invention

[0036] By using the adhesive composition for an electrode of the present invention, even if the solid content concentration of the coating liquid for forming an electrode is increased, an increase in viscosity can be suppressed. Therefore, the adhesive composition for an electrode of the present invention is suitable for preparing a coating liquid for forming an electrode with a high solid content concentration. Detailed Description of Embodiments

[0037] Embodiments of the present invention will be described in detail below. It should be noted that in this specification, the expressions "containing" and "comprising" include concepts such as "containing", "comprising", "substantially consisting of...", and "consisting only of...".

[0038] 1. Binder composition for electrode

[0039] It contains the adhesive composition for an electrode of the present invention. This adhesive composition for an electrode contains a polyurethane resin aqueous dispersion. The D50 volume average particle size of the above polyurethane resin is 0.01 μm or more and 0.05 μm or less, and its D90 volume average particle size is 0.10 μm or more and 0.15 μm or less. That is, the adhesive composition for an electrode of the present invention contains an aqueous dispersion, and this aqueous dispersion contains a polyurethane resin having a specific particle size distribution.

[0040] By including this polyurethane resin in the adhesive composition for an electrode of the present invention, when the adhesive composition for an electrode of the present invention is applied to a coating liquid for forming an electrode, an increase in the viscosity of this coating liquid can be suppressed. In particular, even if the solid content concentration of the above coating liquid is high, an increase in viscosity can be suppressed. Therefore, the adhesive composition for an electrode of the present invention is suitable for preparing a coating liquid with a high solid content concentration and is suitable as an adhesive component (binder) of a coating liquid composition for an electrode used for manufacturing an electrode of an electrical storage device.

[0041] It should be noted that the coating liquid mentioned here refers to a coating liquid containing an electrode active material, an adhesive for an electrode, a dispersant, etc., and is a coating liquid for forming an electrode, especially the coating liquid composition for an electrode of the present invention described later.

[0042] (Polyurethane resin aqueous dispersion)

[0043] The polyurethane resin aqueous dispersion is a dispersion obtained by dispersing a polyurethane resin in an aqueous medium. The type of the polyurethane resin contained in the polyurethane resin aqueous dispersion is not particularly limited as long as it has the above particle size distribution, and for example, publicly known polyurethane resins can be widely cited.

[0044] For example, the polyurethane resin can be formed from the following component (A) and component (B), and may contain one or both of component (C) and component (D) as needed. In other words, the polyurethane resin has structural units based on component (A) and component (B), and has one or both of structural units based on component (C) and component (D) as needed.

[0045] Component (A): A compound having two or more isocyanate groups

[0046] Component (B): A compound having two or more active hydrogen groups

[0047] Component (C): A compound having a hydrophilic group and one or more active hydrogen groups

[0048] Component (D): Chain extender

[0049] As component (A) (a compound having two or more isocyanate groups), publicly known isocyanate compounds can be widely cited. For example, bifunctional isocyanate compounds such as aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, and araliphatic diisocyanates can be cited.

[0050] Examples of the aliphatic diisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, etc. Examples of the alicyclic diisocyanate include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, etc. Examples of the aromatic diisocyanate include tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate, 1,5-naphthalene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, etc. Examples of the araliphatic diisocyanate include dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α,α,α,α-tetramethylxylylene diisocyanate, etc.

[0051] As the component (A), an isocyanate compound having three or more isocyanate groups can be used in place of or in combination with the above bifunctional isocyanate compound.

[0052] The component (A) preferably contains 80% by mass or more of the above bifunctional isocyanate compound, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 95% by mass or more. The component (A) may be only the above bifunctional isocyanate compound. The component (A) can be used alone or in combination of two or more.

[0053] The component (A) can be produced by a known method or obtained from commercially available products.

[0054] Examples of the component (B) (compound having two or more active hydrogen groups) include compounds having two or more hydroxyl groups, two or more amino groups, or two or more mercapto groups at the molecular terminal or in the molecule. Specifically, known polyethers, polyesters, polyether esters, polycarbonates, polysulfides, polyacetals, polyolefins, polysiloxanes, fluorine-based, vegetable oil-based, etc. can be cited. The component (B) may not have a carboxyl group, and may also not have a sulfonic acid group.

[0055] As the component (B), compounds having two or more hydroxyl groups and / or polyol compounds, etc. are preferred. Examples of the compounds having two or more hydroxyl groups include ethylene glycol, propylene glycol, propane diol, butylene glycol, pentylene glycol, 3-methyl-1,5-pentanediol, hexylene glycol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol F, bisphenol S, hydrogenated bisphenol A, dibromobisphenol A, 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, dihydroxyethyl hydroquinone ether, etc.

[0056] Examples of the polyol compounds include well-known polycarbonate polyols, polycaprolactone polyols, polyester polyols, polysulfide polyols, polyacetal polyols, polytetramethylene glycol, polybutadiene polyols, polyisoprene polyols, polychloroprene polyols, etc.

[0057] The polycarbonate polyol is not particularly limited, and for example, well-known polycarbonate polyols can be widely cited. Examples of the polycarbonate polyol include carbonate polyols of 1,6-hexanediol, carbonate polyols of 1,4-butanediol and 1,6-hexanediol, carbonate polyols of 1,5-pentanediol and 1,6-hexanediol, carbonate polyols of 3-methyl-1,5-pentanediol and 1,6-hexanediol, etc.

[0058] In order to introduce a branched structure into the polyurethane resin, the component (B) preferably also contains a compound having three or more active hydrogen groups, which are reactive with isocyanate groups. Specific examples of such compounds include polyols such as trimethylolpropane, glycerin, pentaerythritol, or their alkylene oxide derivatives.

[0059] In addition, in order to locally present urethane bonds in the polyurethane, the component (B) may contain single-chain low-molecular-weight diols such as ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, etc.

[0060] The component (B) can be produced by a well-known method or can also be obtained from commercially available products.

[0061] The component (C) (a compound having one or more active hydrogen groups and a hydrophilic group) is a compound other than the components (A) and (B). For example, the component (C) is a compound other than polyol compounds.

[0062] In the component (C), as the hydrophilic group, it can be any one of an anionic hydrophilic group, a cationic hydrophilic group, and a nonionic hydrophilic group. Examples of the anionic hydrophilic group include a carboxyl group and its salts, and a sulfonic acid group and its salts. Examples of the cationic hydrophilic group include a tertiary amine salt and a quaternary ammonium salt. Examples of the nonionic hydrophilic group include a group containing an ethylene oxide repeating unit, a group containing an ethylene oxide repeating unit and other alkylene oxide repeating units, etc.

[0063] Specific examples of the component (C) include a compound containing one or more active hydrogen groups and one or more carboxyl groups (or their salts), a compound having one or more active hydrogen groups and one or more sulfonic acid groups (or their salts), a tertiary amine salt and one or more active hydrogen groups, a quaternary ammonium salt and one or more active hydrogen groups, and a compound having one or more active hydrogen groups and one or more nonionic hydrophilic groups.

[0064] Examples of the compound containing one or more active hydrogen groups and one or more carboxyl groups (or their salts) include carboxylic acid-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, dioxymaleic acid, 2,6-dioxobenzoic acid, 3,4-diaminobenzoic acid and their derivatives and their salts, and polyester polyols obtained by using carboxylic acid-containing compounds. In addition, examples of the compound containing one or more active hydrogen groups and one or more carboxyl groups (or their salts) also include amino acids such as alanine, aminobutyric acid, aminohexanoic acid, glycine, glutamic acid, aspartic acid, histidine; carboxylic acids such as succinic acid, adipic acid, maleic anhydride, phthalic acid, trimellitic anhydride.

[0065] Examples of the compound having one or more active hydrogen groups and one or more sulfonic acid groups (or their salts) include sulfonic acid-containing compounds such as 2-hydroxyethanesulfonic acid, phenolsulfonic acid, sulfobenzoic acid, sulfosuccinic acid, 5-sulfoisophthalic acid, sulfanilic acid, 1,3-phenylenediamine-4,6-disulfonic acid, 2,4-diaminotoluene-5-sulfonic acid and their derivatives, and polyester polyols, polyamide polyols, polyamide polyester polyols, etc. obtained by copolymerizing two or more of the above sulfonic acid-containing compounds.

[0066] Both the compound having one or more active hydrogen groups and one or more carboxyl groups (or their salts) and the compound having one or more active hydrogen groups and one or more sulfonic acid groups (or their salts) can be salts in which the carboxyl group or sulfonic acid group is neutralized by a neutralizing agent. Thereby, the dispersibility of the polyurethane resin in water becomes good. Examples of the neutralizing agent include non-volatile bases such as sodium hydroxide and potassium hydroxide; tertiary amines such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, and triethanolamine; volatile bases such as ammonia.

[0067] Examples of the compound containing a tertiary amine salt and one or more active hydrogen groups include alkanolamines such as methylaminoethanol and methyldiethanolamine. The tertiary amine salt can be a salt neutralized by a neutralizing agent. Thereby, the dispersibility of the polyurethane resin in water becomes good. Examples of the neutralizing agent include organic carboxylic acids such as formic acid and acetic acid, or hydrochloric acid, sulfuric acid, etc. From the viewpoint of ease of emulsification, the compound containing a tertiary amine salt and one or more active hydrogen groups is preferably one obtained by neutralizing methyldiethanolamine with an organic carboxylic acid. The neutralization can be carried out at any stage before, during, and after the formation of the urethane resin.

[0068] Examples of the compound having a quaternary ammonium salt and one or more active hydrogen groups include compounds obtained by quaternizing the above-mentioned alkanolamines such as methylaminoethanol and methyldiethanolamine with a haloalkyl such as chloromethane and bromomethane, or a dialkyl sulfate such as dimethyl sulfate. From the viewpoint of ease of emulsification, the compound having a quaternary ammonium salt and one or more active hydrogen groups is preferably a compound obtained by quaternizing methyldiethanolamine with dimethyl sulfate or the like.

[0069] The compound having one or more active hydrogen groups and one or more nonionic hydrophilic groups is not particularly limited, and a compound containing at least 30% by mass or more of ethylene oxide repeating units and having a number average molecular weight of 300 to 20,000 is preferred. Examples of such a compound include compounds containing nonionic groups such as polyethylene glycol, poly(ethylene oxide - propylene oxide) copolymer diol, poly(ethylene oxide - butylene oxide) copolymer diol, poly(ethylene oxide - polyalkylene oxide) copolymer diol or its monoalkyl ether, and polyester polyether polyols obtained by copolymerizing them.

[0070] Component (C) is preferably a compound containing one or more active hydrogen groups and one or more carboxyl groups. At this time, the adhesion of the electrode adhesive composition of the present invention to the current collector is easily improved.

[0071] When component (C) is a compound containing an anionic hydrophilic group, from the viewpoint of easily making the dispersibility excellent, the acid value indicating the content of the anionic hydrophilic group of the polyurethane resin is preferably 5 to 50 mgKOH / g, more preferably 5 to 45 mgKOH / g. The acid value can be determined according to JIS K0070 - 1992 by the number of mg of KOH required to neutralize the free carboxyl groups contained in 1 g of the solid content of the polyurethane aqueous dispersion. When component (C) is a compound containing a nonionic group, the content of the compound containing a nonionic group is preferably 1 to 30 parts by mass, more preferably 3 to 25 parts by mass, and further preferably 5 to 20 parts by mass with respect to 100 parts by mass of the polyurethane resin.

[0072] Component (C) can be produced by a known method or can also be obtained from commercially available products.

[0073] As the component (D), for example, chain extenders used in the production of urethane resins can be widely cited. Specifically, as the component (D), diamine compounds and polyamine compounds can be cited. Examples of diamine compounds include ethylenediamine, trimethylenediamine, piperazine, isophoronediamine, amino group-containing silane coupling agents, etc., and examples of polyamine compounds include diethylenetriamine, dipropylenetriamine, triethylenetetramine, etc. As the component (D), in order to introduce an internal crosslinked structure into the polyurethane and improve the electrolyte resistance, polyamines having three or more functional groups are also preferably contained.

[0074] In the polyurethane resin, the content ratio of the structural unit based on the component (D) (chain extender) per 100 parts by mass of the polyurethane resin can be, for example, 0.1 part by mass or more and 3 parts by mass or less, preferably 0.2 part by mass or more and 1 part by mass or less.

[0075] The polyurethane resin can be formed only from the structural units based on the above-mentioned components (A), (B), (C), and (D), and other structural units can also be included as long as the effects of the present invention are not hindered. The content ratio of the structural units based on the above-mentioned components (A), (B), (C), and (D) contained in the polyurethane resin is not particularly limited, and can be, for example, the same as that of known polyurethane resins.

[0076] From the viewpoint of being less likely to reduce flexibility and being easily excellent in adhesiveness, the amount of urethane bonds in the polyurethane resin is preferably 300 to 20000 g / eq, more preferably 400 to 10000 g / eq.

[0077] The number average molecular weight of the polyurethane resin is not particularly limited. For example, from the viewpoint of being easily formable into a coating film, it can be 50000 or more and 1000000 or less. In addition, the crosslinking density of the polyurethane resin is not particularly limited. For example, per 1000 molecular weights of the polyurethane resin, it is preferably 0.01 to 0.50. It should be noted that the crosslinking density of the polyurethane resin can be measured by a known method.

[0078] As described above, the D50 volume average particle diameter of the polyurethane resin is 0.01 μm or more and 0.05 μm or less, and the D90 volume average particle diameter is 0.10 μm or more and 0.15 μm or less. By making the polyurethane resin have such a particle size distribution, the electrode binder composition containing the polyurethane resin aqueous dispersion can suppress the increase in the viscosity of the coating liquid for forming an electrode. Therefore, even when the solid content concentration of the coating liquid is high, the viscosity is not likely to increase. Therefore, the electrode binder composition containing the polyurethane resin aqueous dispersion is suitable for preparing a coating liquid with a high solid content concentration and is suitable as a binder component (adhesive) for an electrode coating liquid composition used for manufacturing an electrode of an electric storage device.

[0079] Here, the D50 volume average particle diameter refers to the particle diameter at the point where the volume cumulative distribution in the particle size distribution curve of the polyurethane resin is 50%, and the D90 volume average particle diameter refers to the particle diameter at the point where the volume cumulative distribution in the particle size distribution curve of the polyurethane resin is 90%. The D50 volume average particle diameter and D90 volume average particle diameter (hereinafter simply referred to as "D50" and "D90", respectively) of the polyurethane resin refer to the values measured using a dynamic light scattering (DLS) particle size distribution measuring device (Nanotrac WaveII (manufactured by Microtrac Bell)).

[0080] When the D50 of the polyurethane resin in the polyurethane resin aqueous dispersion is less than 0.01 μm, the synthesis method of the polyurethane resin aqueous dispersion becomes extremely complicated or it is difficult to synthesize. In addition, if the D50 of the polyurethane resin in the polyurethane resin aqueous dispersion exceeds 0.05 μm, it is difficult to suppress the increase in the viscosity of the coating liquid, and as a result, it is difficult to increase the solid content concentration of the coating liquid. The D50 of the polyurethane resin in the polyurethane resin aqueous dispersion is preferably 0.015 μm or more, more preferably 0.02 μm or more.

[0081] When the D90 of the polyurethane resin in the polyurethane resin aqueous dispersion is less than 0.10 μm, it is difficult to suppress the increase in the viscosity of the coating liquid, and as a result, it is difficult to increase the solid content concentration of the coating liquid. In addition, if the D90 of the polyurethane resin in the polyurethane resin aqueous dispersion exceeds 0.15 μm, it is difficult to suppress the increase in the viscosity of the coating liquid, and as a result, it is difficult to increase the solid content concentration of the coating liquid. The D90 of the polyurethane resin in the polyurethane resin aqueous dispersion is preferably 0.11 μm or more.

[0082] The method for adjusting the D50 and D90 of the polyurethane resin in the polyurethane resin aqueous dispersion is not particularly limited. For example, a method of controlling the particle size distribution of the polyurethane resin aqueous dispersion can be widely adopted. Specifically, as described later, in the manufacture of the polyurethane resin aqueous dispersion, it is preferable to adjust the D50 and D90 of the polyurethane resin by controlling the emulsification and dispersion conditions. In addition, the D50 and D90 of the polyurethane resin can also be adjusted according to the usage amounts of raw materials ((A) component, (B) component, (C) component, (D) component, and chain length extender) used in the manufacture of the polyurethane resin, the usage ratio of water, etc.

[0083] In the polyurethane resin aqueous dispersion, the type of the dispersion medium as the medium is not particularly limited, and water, lower alcohols having 1 to 3 carbon atoms, and their mixed solvents can be mentioned. Among them, from the viewpoint of excellent dispersion of the polyurethane resin, the dispersion medium is preferably water.

[0084] The solid content concentration of the polyurethane resin aqueous dispersion is not particularly limited. From the perspective of operability, etc., the solid content concentration of the polyurethane resin aqueous dispersion is preferably 1% by mass or more and 60% by mass or less, more preferably 3% by mass or more and 55% by mass or less, and further preferably 4% by mass or more and 50% by mass or less.

[0085] (Method for producing polyurethane resin aqueous dispersion)

[0086] The method for producing the polyurethane resin aqueous dispersion is not particularly limited. For example, the same method as the known method for producing a polyurethane resin aqueous dispersion can be adopted. For example, a urethane prepolymer is prepared by mixing the above components (A), (B), and, if necessary, (C), and the urethane prepolymer is emulsified and dispersed, whereby a polyurethane resin aqueous dispersion can be obtained. The mixing treatment can be carried out in a solvent as needed. The solvent preferably has the following properties: it is non-reactive with respect to the isocyanate group and can dissolve the resulting urethane prepolymer. From this perspective, solvents that can be mentioned are: dioxane, methyl ethyl ketone, dimethylformamide, tetrahydrofuran, N-methyl-2-pyrrolidone, acetone, toluene, dioxane, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, etc. The solvent used in the reaction is preferably removed finally.

[0087] The temperature of the above mixing treatment is not particularly limited. For example, it can be set to 30°C to 130°C. The time of the mixing treatment can be appropriately set according to the temperature. For example, it is 0.5 hour to 10 hours. By the mixing treatment, the reaction between the components (A) and (B) occurs to generate a urethane prepolymer. When the mixing treatment is carried out in a solvent, a urethane prepolymer solution is obtained. After the urethane prepolymer is generated and before the emulsification and dispersion, the neutralization of the anionic hydrophilic group, the neutralization of the cationic hydrophilic group, or the quaternization of the component (C) can be carried out by a known method as needed.

[0088] In the above mixing treatment, the amounts of the components (A), (B), and (C) used are not particularly limited. For example, the same amounts used as in the known method can be adopted. For example, the component (A) can be used in such a way that the total amount of the active hydrogen groups having reactivity with the isocyanate group in the components (B), (C), and (D) and the equivalent ratio of the isocyanate group of the component (A) reaches 1:0.85 to 1:1.1. The component (A) can be used in an excess amount stoichiometrically.

[0089] The method for emulsifying and dispersing the urethane prepolymer obtained by the mixing treatment is not particularly limited, and publicly known methods can be widely adopted. For example, by mixing a solution of the urethane prepolymer with alkaline water and applying shear using an emulsifying and dispersing machine such as a homogenizer, the urethane prepolymer can be emulsified and dispersed.

[0090] Examples of the alkaline water used in the emulsifying and dispersing process include aqueous solutions of various alkaline components. Among them, as the alkaline component, sodium hydroxide is preferred. That is, the alkaline water is preferably an aqueous solution of sodium hydroxide. In this case, it is easy to adjust the D50 and D90 of the polyurethane resin to the desired range. From the perspective of easily adjusting the D50 and D90 of the polyurethane resin to the desired range, the concentration of the alkaline water is preferably 0.5% by mass to 1% by mass, more preferably 0.6% by mass to 0.9% by mass, and further preferably 0.65% by mass to 0.85% by mass. It is also possible to mix the solution of the urethane prepolymer with alkaline water, and after applying shear using an emulsifying and dispersing machine such as a homogenizer, further add water.

[0091] The method for mixing the solution of the urethane prepolymer with alkaline water is not particularly limited, and the D50 and D90 of the polyurethane resin can be appropriately adjusted to the desired range. For example, it is preferred to add the alkaline water dropwise to the solution of the urethane prepolymer and mix. From the perspective of easily adjusting the D50 and D90 of the polyurethane resin to the desired range, relative to 100 parts by mass of the urethane prepolymer, the dropwise addition amount (i.e., the dropwise addition amount of the alkaline component per minute) in terms of the alkaline component is preferably 0.55×10 -2 (parts by mass / minute) or more and 1×10 -2 (parts by mass / minute) or less. During the dropwise addition of the alkaline water, relative to 100 parts by mass of the urethane prepolymer, the dropwise addition amount in terms of the alkaline component is preferably 0.6×10 -2 (parts by mass / minute) or more, more preferably 0.65×10 -2 (parts by mass / minute) or more, further preferably 0.66×10 -2 (parts by mass / minute) or more, and preferably 0.95×10 -2 (parts by mass / minute) or less, more preferably 0.9×10 -2 (parts by mass / minute) or less, and further preferably 0.85×10 -2 (parts by mass / minute) or less.

[0092] From the perspective of easily adjusting the D50 and D90 of the polyurethane resin to the desired range, relative to 100 parts by mass of the urethane prepolymer, it is preferable to add the basic water in such a way that the dropping amount in terms of water conversion (i.e., the dropping amount of water per minute) is 0.6 (parts by mass / minute) or more and 5 (parts by mass / minute) or less. Relative to 100 parts by mass of the urethane prepolymer, the dropping amount of water contained in the basic water is more preferably 0.7 (parts by mass / minute) or more, further preferably 0.8 (parts by mass / minute) or more, and particularly preferably 0.9 (parts by mass / minute) or more. In addition, relative to 100 parts by mass of the urethane prepolymer, the dropping amount of water contained in the basic water is more preferably 4 (parts by mass / minute) or less, further preferably 3.5 (parts by mass / minute) or less, and particularly preferably 3 (parts by mass / minute) or less.

[0093] It should be noted that in this specification, the total mass of the urethane prepolymer in the solution of the urethane prepolymer can be the same as the total usage amount of the components (A), (B), and (C) used in the production of the urethane prepolymer.

[0094] From the perspective of easily making the particle size distribution of the polyurethane resin fall within the desired range, relative to 100 parts by mass of the urethane prepolymer, the total mass of the basic water and water used in the emulsification and dispersion is preferably set to 100 to 900 parts by mass, more preferably set to 110 to 800 parts by mass, and further preferably set to 120 to 700 parts by mass.

[0095] As described above, in the present invention, by adjusting the conditions of emulsification and dispersion, particularly the basic water used in the emulsification and dispersion or its addition rate, it is easy to adjust the D50 and D90 of the polyurethane resin to the desired range.

[0096] It is also possible to add the component (D) for chain extension simultaneously with or after the above-mentioned emulsification and dispersion. Thereby, urethane bonds are formed through the interfacial polymerization reaction between the isocyanate groups in the emulsion micelles and the chain extender as the component (D), so the crosslinking density within the emulsion micelles increases and a three-dimensional crosslinked structure is formed. It should be noted that even when the component (D) is not used, chain extension may be caused by the water molecules present in the system through the emulsification and dispersion of the urethane prepolymer in water.

[0097] When the component (D) is used, its usage amount is not particularly limited. For example, the usage amount of the component (D) can be adjusted in such a way that the equivalent ratio of the isocyanate groups in the urethane prepolymer to the component (D) becomes 1:0.5 to 1:0.9.

[0098] After the emulsification and dispersion, the solvent and the like used as required are removed, whereby a polyurethane aqueous dispersion can be obtained.

[0099] The D50 of the polyurethane resin aqueous dispersion obtained by the above method is 0.01 μm or more and 0.05 μm or less, and the D90 is 0.10 μm or more and 0.15 μm or less. Therefore, as described above, it is applicable to the binder composition for electrodes of the present invention.

[0100] (Other components contained in the binder composition for electrodes)

[0101] In the binder composition for electrodes of the present invention, in addition to the above polyurethane resin aqueous dispersion, other components may be contained. There is no particular limitation on the other components. For example, they can be used in the same manner as known binder compositions for electrodes.

[0102] For example, the binder composition for electrodes of the present invention may contain carbon nanotubes. The type of carbon nanotubes is not particularly limited. For example, it can be the same as the carbon nanotubes contained in known binder compositions for electrodes. Specific examples of carbon nanotubes include single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), etc. From the perspective of being able to improve the electron conductivity with a small amount, single-walled carbon nanotubes are preferred.

[0103] There is no particular limitation on the fiber diameter and fiber length of the carbon nanotubes. For example, the number-average fiber diameter is preferably 0.5 nm or more and 20 nm or less, and the number-average fiber length is preferably 0.5 μm or more and 1 mm or less. By making the number-average fiber diameter 0.5 nm or more, the viscosity can be prevented from becoming too high, so it is easy to prepare the coating composition for electrodes described later. In addition, by making the number-average fiber diameter 20 nm or less, the flexibility is improved, so the durability when making a battery is easily improved. The number-average fiber diameter is more preferably 1 nm or more and 10 nm or less, and further preferably 2 nm or more and 8 nm or less. In addition, by making the number-average fiber length 0.5 μm or more, the durability of the obtained electrode is easily improved, and the cycle life of the obtained battery is easily improved. By setting the number-average fiber length to 1 mm or less, the rheological control of the carbon nanotubes becomes easy. The number-average fiber length is more preferably 1 μm or more and 10 μm or less, and further preferably 2 μm or more and 7 μm or less. The number-average fiber length and the number-average fiber diameter can be measured, for example, by measuring the major axis and diameter of 100 randomly selected carbon nanotubes in a transmission electron microscope photograph or a scanning probe microscope photograph and calculating their average values.

[0104] When the binder composition for electrodes of the present invention contains carbon nanotubes, its content is not particularly limited. For example, relative to 100 parts by mass of the urethane resin, its content is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass.

[0105] When the binder composition for an electrode of the present invention contains carbon nanotubes, the binder composition for an electrode of the present invention may also contain a dispersant A. Thereby, it is easy to improve the dispersibility of carbon nanotubes in the binder composition for an electrode.

[0106] Examples of the above-mentioned dispersant A include: cellulose-based substances such as hydroxymethylcellulose, carboxymethylcellulose and its alkali metal salts, methylcellulose, ethylcellulose, hydroxypropylmethylcellulose, and hydroxyethylmethylcellulose. Among them, carboxymethylcellulose or its salt is more preferable. When the binder composition for an electrode of the present invention contains carboxymethylcellulose or its salt, the dispersibility of carbon nanotubes is more easily further improved. The carboxymethylcellulose or its salt is particularly preferably the sodium salt of carboxymethylcellulose.

[0107] When the binder composition for an electrode of the present invention contains the above-mentioned dispersant A, its content is not particularly limited. For example, relative to 100 parts by mass of the urethane resin, it is preferably 0.1 to 10 parts by mass, and more preferably 0.2 to 8 parts by mass.

[0108] In the binder composition for an electrode of the present invention, various components such as an antioxidant and a light stabilizer may be further contained. The binder composition for an electrode of the present invention preferably contains 60% by mass or more of the above-mentioned urethane resin aqueous dispersion, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0109] The method for manufacturing the binder composition for an electrode of the present invention is not particularly limited. The manufacturing method of the binder composition for an electrode of the present invention includes a step of preparing the above-mentioned urethane resin aqueous dispersion. That is, the manufacturing method of the binder composition for an electrode of the present invention includes a step of preparing a urethane resin aqueous dispersion having a D50 volume average particle diameter of 0.01 μm or more and 0.05 μm or less, and a D90 volume average particle diameter of 0.10 μm or more and 0.15 μm or less. The urethane resin aqueous dispersion can be obtained by the above-mentioned manufacturing method of the urethane resin aqueous dispersion.

[0110] When the binder composition for an electrode of the present invention contains carbon nanotubes and / or dispersant A, for example, the binder composition for an electrode can be prepared by mixing the above-mentioned binder composition for an electrode, the urethane resin aqueous dispersion, with carbon nanotubes and / or dispersant A. The carbon nanotubes and / or dispersant A can be used in a state of being dispersed or dissolved in a dispersion medium. In this case, the dispersion medium can be set to be the same as the dispersion medium of the urethane resin aqueous dispersion.

[0111] As described above, the binder composition for an electrode of the present invention is suitable as a binder component (binder) for an electrode coating liquid composition used for manufacturing an electrode for an electric storage device. In particular, the binder composition for an electrode of the present invention can suppress an increase in the viscosity of the above coating liquid, and even if the solid content concentration of the coating liquid is increased, the viscosity is not likely to increase. Therefore, an electrode coating liquid composition containing the binder composition for an electrode of the present invention can form an electrode having excellent performance.

[0112] 2. Coating liquid composition for electrode

[0113] As long as the electrode coating liquid composition of the present invention contains the binder composition for an electrode, other components contained therein are not particularly limited. For example, the electrode coating liquid composition of the present invention may further contain components contained in a known electrode coating liquid composition.

[0114] Specifically, in the electrode coating liquid composition of the present invention, in addition to the binder composition for an electrode, an active material and a conductive auxiliary agent are further contained, and a dispersant B or the like may be contained as needed.

[0115] (Active material)

[0116] The active material may be a positive electrode active material or a negative electrode active material. From the viewpoint of improving dispersibility and making the viscosity less likely to increase even when the solid content concentration is increased, a negative electrode active material is preferred.

[0117] As the positive electrode active material, known positive electrode active materials can be widely cited, and various positive electrode active materials capable of inserting / removing lithium ions can be cited. As specific examples, in addition to metal oxides such as CuO, Cu2O, MnO2, MoO3, V2O5, and CrO3, and composite oxides of lithium and transition metals such as LixCoO2 and LixNiO2, metal chalcogenides, conductive polymer compounds, etc. can also be listed. Among them, from the viewpoints of lithium ion release property and easy attainment of a high voltage, a composite oxide of one or more selected from transition metals such as cobalt, nickel, and manganese and lithium, which is generally referred to as a high voltage type, is usually preferred.

[0118] As the negative electrode active material, known negative electrode active materials can be widely cited, and various negative electrode active materials capable of inserting / removing metallic lithium or lithium ions can be cited. As specific examples, carbon materials such as natural graphite, artificial graphite, hardly graphitizable carbon, and easily graphitizable carbon can be cited; metal materials such as metallic lithium, alloys, and tin compounds; lithium transition metal nitrides; crystalline metal oxides; amorphous metal oxides; silicon compounds; conductive polymers, etc. Among them, from the viewpoint that the viscosity does not particularly increase even when the solid content concentration is increased, a silicon compound is more preferred, and SiO is further preferred.

[0119] (Conductive aid)

[0120] As a conductive aid, electronically conductive materials that do not adversely affect battery performance can be widely cited. For example, in addition to carbon blacks such as acetylene black and Ketjen black, conductive materials such as natural graphite (flake graphite, scaly graphite, earthy graphite, etc.), artificial graphite, carbon whiskers, carbon fibers, metal (copper, nickel, aluminum, silver, gold, etc.) powders, metal fibers, and conductive ceramic materials can also be cited. In addition, when the electrode binder composition contains carbon nanotubes, the electrode coating liquid composition may not contain carbon nanotubes. The conductive aid contained in the electrode coating liquid composition can be one kind or two or more kinds.

[0121] In the electrode coating liquid composition, the content ratio of the conductive aid can be set to be the same as that of a known electrode coating liquid composition. For example, relative to the active material, it is preferably 0.1% by mass to 30% by mass, and preferably 0.2% by mass to 20% by mass.

[0122] (Dispersant B)

[0123] The dispersant B is not particularly limited, and dispersants contained in known electrode coating liquid compositions can be widely cited. As specific examples, there can be cited: cellulose-based materials such as hydroxymethyl cellulose, carboxymethyl cellulose and its alkali metal salts, methyl cellulose, ethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, etc.; cellulose nanofiber-based materials such as chemically modified cellulose nanofibers; polycarboxylic acid-based compounds such as polyacrylic acid and sodium polyacrylate; compounds having a vinylpyrrolidone structure such as polyvinylpyrrolidone; and polymer compounds such as polyester resins, polyacrylamides, polyethylene oxides, polyvinyl alcohols, sodium alginate, xanthan gum, carrageenan, guar gum, agar, starch, etc. Among them, the dispersant B is preferably a cellulose-based material, and particularly preferably a carboxymethyl cellulose salt. In addition, when the electrode binder composition contains the dispersant A, the electrode coating liquid composition may not contain the dispersant B, or may contain a dispersant B of a different type from the dispersant A. The dispersant B contained in the electrode coating liquid composition can be one kind or two or more kinds.

[0124] In the electrode coating liquid composition, the content ratio of the dispersant B (except for the polyurethane resin in the polyurethane resin aqueous dispersion) can be set to be the same as that of a known electrode coating liquid composition. For example, relative to the solid content in the electrode coating liquid composition, it can be 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, particularly preferably 0.3% by mass or more. In addition, it can be 5% by mass or less, preferably 3% by mass or less, more preferably 2.5% by mass or less, further preferably 2% by mass or less, particularly preferably 1.5% by mass or less.

[0125] (Other components)

[0126] In addition, the coating liquid composition for electrodes may further contain a surfactant. As the surfactant, surfactants included in known coating liquid compositions for electrodes can be widely cited, and any of nonionic surfactants, anionic surfactants, and cationic surfactants can be used.

[0127] Examples of the nonionic surfactant include alkynediol-based nonionic surfactants. Examples of the alkynediol-based nonionic surfactant include Surfynol 420, Surfynol 423, Surfynol 424, Surfynol 425, Surfynol 440, Surfynol 465 manufactured by Nissin Chemical Industry Co., Ltd., TRITON (registered trademark) HW-1000 manufactured by The Dow Chemical Company, Orfin AF-103, Orfin AF-300 manufactured by Nissin Chemical Industry Co., Ltd., and Antifoam 013A manufactured by Kao Corporation. The nonionic surfactant can be a fluorine-based surfactant or a silicone-based surfactant.

[0128] In the coating liquid composition for electrodes, the content ratio of the surfactant can be set to be the same as that in known coating liquid compositions for electrodes. For example, relative to the solid components in the coating liquid composition for electrodes, it can be 0.001% by mass or more, preferably 0.005% by mass or more, more preferably 0.01% by mass or more, further preferably 0.02% by mass or more, particularly preferably 0.03% by mass or more. Additionally, it can be 3% by mass or less, preferably 2% by mass or less, more preferably 1% by mass or less, further preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less.

[0129] In addition, the coating liquid composition for electrodes may contain various additives as needed, such as weathering agents, antibacterial agents, antifungal agents, pigments, rust inhibitors, dyes, film-forming aids, silane coupling agents, anti-blocking agents, viscosity regulators, leveling agents, defoamers, dispersion stabilizers, light stabilizers, antioxidants, ultraviolet absorbers, inorganic fillers, organic fillers, plasticizers, lubricants, antistatic agents, etc.

[0130] (Coating Liquid Composition for Electrodes)

[0131] The coating liquid composition for electrodes contains a polyurethane resin derived from the binder composition for electrodes. From the perspective of not easily causing an increase in the viscosity of the coating liquid composition for electrodes, the content ratio of the polyurethane resin relative to the active material can be 0.5% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, further preferably 5% by mass or more, and particularly preferably 7% by mass or more. Additionally, from the perspective of not easily causing an increase in the viscosity of the coating liquid composition for electrodes, the content ratio of the polyurethane resin relative to the active material can be 30% by mass or less, preferably 25% by mass or less, more preferably 20% by mass or less, further preferably 15% by mass or less, and particularly preferably 13% by mass or less.

[0132] The solvent contained in the coating liquid composition for electrodes is not particularly limited. For example, it can be the same as the solvent contained in the polyurethane resin aqueous dispersion, or it can be different.

[0133] The solid content concentration of the coating liquid composition for electrodes is not particularly limited. The higher the solid content concentration, the more active material and the like can be contained, so that the binder effect can be improved and the electrode performance can be enhanced. From this perspective, the solid content concentration of the coating liquid composition for electrodes is preferably 40% by mass or more, more preferably 43% by mass or more, further preferably 45% by mass or more, and particularly preferably 48% by mass or more. The solid content concentration of the coating liquid composition for electrodes can also be set to 50% by mass or more. Additionally, from the perspective of not easily causing aggregation and having excellent coatability, the solid content concentration of the coating liquid composition for electrodes is preferably 60% by mass or less, more preferably 55% by mass or less, and further preferably 53% by mass or less.

[0134] From the perspective of not easily occurring aggregation and having excellent coatability, the viscosity of the coating liquid composition for electrodes of the present invention at a solid content concentration of 50% by mass is preferably 1000 - 25000 mPa·s, more preferably 2000 - 23000 mPa·s, further preferably 3000 - 20000 mPa·s, and particularly preferably 3000 - 18000 mPa·s. The viscosity of the coating liquid composition for electrodes of the present invention refers to the value measured by a B-type rotational viscometer (25°C, 6 rpm).

[0135] The method for preparing the coating liquid composition for electrodes of the present invention is not particularly limited. For example, it can adopt the same method as the known method for preparing the coating liquid composition for electrodes. For example, it can be prepared by mixing the active material, the conductive auxiliary agent, the dispersant, and the binder composition for electrodes in a specified content ratio. During this mixing, for example, a homogenizing disperser, a planetary mixer, a propeller mixer, a kneader, a homogenizer, an ultrasonic homogenizer, a colloid mill, a bead mill, a sand mill, a high-pressure homogenizer, etc. can be used.

[0136] By using the coating liquid composition for electrodes of the present invention, an electrode for an electrical storage device can be formed. For example, by coating the coating liquid composition for electrodes on a current collector to form a coating film, an electrode can be formed. Therefore, the electrode for an electrical storage device contains the solid components of the coating liquid composition for electrodes. In particular, the coating liquid composition for electrodes can have a higher solid component concentration than existing coating liquid compositions for electrodes, so it is easy to form an electrode that fully exhibits the function of a binder and has excellent properties.

[0137] The method of coating the coating liquid composition for electrodes of the present invention on a current collector is not particularly limited, and for example, known coating methods can be widely used.

[0138] The type of the current collector coated with the coating liquid composition for electrodes of the present invention is not particularly limited, and for example, it can be widely applied to the current collector for the positive electrode and the negative electrode current collector used in a lithium secondary battery. Examples of the current collector for the positive electrode include aluminum, titanium, stainless steel, nickel, fired carbon, conductive polymer, conductive glass, etc., and examples of the negative electrode current collector include copper, stainless steel, nickel, aluminum, titanium, fired carbon, conductive polymer, conductive glass, Al-Cd alloy, etc.

[0139] The electrode for an electrical storage device obtained by using the coating liquid composition for electrodes of the present invention can be applied to various electrical storage devices. The electrical storage device includes the electrode for an electrical storage device obtained by using the coating liquid composition for electrodes of the present invention, so it can have excellent properties. Examples of the electrical storage device include known electrical storage devices, such as lithium secondary batteries, lithium ion capacitors, etc.

[0140] The configuration of the electrical storage device is not particularly limited, as long as it includes the electrode for an electrical storage device obtained by using the coating liquid composition for electrodes of the present invention. For example, it can adopt the same configuration as known electrical storage devices.

[0141] The electrical storage device (such as a lithium secondary battery) can be formed into a cylindrical shape, a coin shape, a square shape, or any other arbitrary shape. The basic structure of the battery is the same regardless of the shape, and it can be designed and modified according to the purpose.

[0142] When determining the inventions included in the present invention, the various structures (properties, structures, functions, etc.) described in the respective embodiments of the present invention can be combined arbitrarily. That is, in the present invention, it includes the subject matter composed of all combinations of the various structures that can be combined as described in this specification.

[0143] Examples

[0144] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the embodiments described below.

[0145] (Production Example 1: Polyurethane resin aqueous dispersion A1)

[0146] In a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen inlet tube, 71.3 parts by mass of polybutadiene polyol (manufactured by Idemitsu Kosan Co., Ltd., Polybd R-45HT, average hydroxyl value 46.5 mgKOH / g), 4.2 parts by mass of dimethylolpropionic acid, 24.5 parts by mass of dicyclohexylmethane diisocyanate, and 100 parts by mass of methyl ethyl ketone were added. Then, the reaction was carried out at 75 °C for 4 hours to obtain a methyl ethyl ketone solution of a polyurethane prepolymer. The content of free isocyanate groups was 2.5% relative to the non-volatile components of the methyl ethyl ketone solution. Next, after cooling the solution to 45 °C, emulsification and dispersion were carried out as follows. In the above methyl ethyl ketone solution, while adding 186 parts by mass of water in which 1.25 parts by mass of sodium hydroxide was dissolved at a rate of 1 part by mass / minute (converted to 0.67×10 -2 parts by mass / minute in terms of the basic component) and carrying out emulsification and dispersion using a homogenizer, 114 parts by mass of water was further added for emulsification and dispersion. After adding an aqueous solution prepared by dissolving 1.6 parts by mass of ethylenediamine in 24 parts by mass of water to the obtained emulsified dispersion, a chain extension reaction was carried out for 1 hour. Then, methyl ethyl ketone as a reaction solvent was distilled off under reduced pressure at 50 °C to obtain a polyurethane resin aqueous dispersion A1 with a solid content concentration of 30% by mass.

[0147] (Production Example 2: Polyurethane resin aqueous dispersion A2)

[0148] In the above methyl ethyl ketone solution, while adding 150 parts by mass of water in which 1.25 parts by mass of sodium hydroxide was dissolved at a rate of 1 part by mass / minute (converted to 0.83×10 -2 parts by mass / minute in terms of the basic component) and carrying out emulsification and dispersion using a homogenizer, 150 parts by mass of water was further added for emulsification and dispersion. Except for this, a polyurethane resin aqueous dispersion A2 with a solid content concentration of 30% by mass was obtained by the same method as in Production Example 1.

[0149] (Production Example 3: Polyurethane resin aqueous dispersion A3)

[0150] In the above methyl ethyl ketone solution, while adding 450 parts by mass of water in which 1.25 parts by mass of sodium hydroxide was dissolved at a rate of 3 parts by mass / minute (converted to 0.83×10 -2 parts by mass / minute in terms of the basic component) and carrying out emulsification and dispersion using a homogenizer, 150 parts by mass of water was further added for emulsification and dispersion. Except for this, a polyurethane resin aqueous dispersion A3 with a solid content concentration of 30% by mass was obtained by the same method as in Production Example 1.

[0151] (Production Example 4: Polyurethane resin aqueous dispersion A4)

[0152] The polybutadiene polyol was changed to hydrogenated polybutadiene polyol (manufactured by Nippon Soda Co., Ltd., NISSO-PB GI-2000). Except for this, a polyurethane resin aqueous dispersion A4 with a solid content concentration of 30% by mass was obtained by the same method as in Production Example 1.

[0153] (Production Example 5: Polyurethane resin aqueous dispersion A5)

[0154] In the above methyl ethyl ketone solution, while adding 300 parts by mass of water in which 1.25 parts by mass of sodium hydroxide was dissolved at a rate of 6 parts by mass per minute (converted to 2.4×10 -2 parts by mass per minute in terms of the basic component) and performing emulsification and dispersion using a homogenizer, a polyurethane resin aqueous dispersion A3 with a solid content concentration of 30% by mass was obtained by the same method as in Production Example 1.

[0155] (Production Example 6: Polyurethane resin aqueous dispersion A6)

[0156] In order to obtain a polyurethane resin aqueous dispersion with a 50% cumulative particle size less than 0.01 μm and a 90% cumulative particle size of 0.1 - 0.15 μm, in the above methyl ethyl ketone solution, while adding 122 parts by mass of water in which 1.25 parts by mass of sodium hydroxide was dissolved at a rate of 1 part by mass per minute (converted to 1.02×10 -2 parts by mass per minute in terms of the basic component) and performing emulsification and dispersion using a homogenizer, and further adding 178 parts by mass of water for emulsification and dispersion. Except for this, the same method as in Production Example 1 was carried out, but a polyurethane resin aqueous dispersion A6 with a 50% cumulative particle size less than 0.01 μm could not be obtained.

[0157] (Production Example 7: Polyurethane resin aqueous dispersion A7)

[0158] In order to obtain a polyurethane resin aqueous dispersion with a 50% cumulative particle size exceeding 0.05 μm and a 90% cumulative particle size of 0.1 - 0.15 μm, in the above methyl ethyl ketone solution, while adding 233 parts by mass of water in which 1.25 parts by mass of sodium hydroxide was dissolved at a rate of 1 part by mass per minute (converted to 0.54×10 -2 parts by mass per minute in terms of the basic component) and performing emulsification and dispersion using a homogenizer, and further adding 67 parts by mass of water for emulsification and dispersion. Except for this, the same method as in Production Example 1 was carried out, but a polyurethane resin aqueous dispersion A7 with a 50% cumulative particle size exceeding 0.05 μm could not be obtained.

[0159] (Production Example 8: Polyurethane resin aqueous dispersion A8)

[0160] In the above methyl ethyl ketone solution, at a rate of 0.5 part by mass per minute (converted to 0.42×10 -2While adding 150 parts by mass of water in which 1.25 parts by mass of sodium hydroxide was dissolved at a rate of 1.25 parts by mass per minute, emulsification and dispersion were carried out using a homogenizer. Further, 150 parts by mass of water was added for emulsification and dispersion. In addition, by the same method as in Production Example 1, an aqueous polyurethane resin dispersion A8 having a solid content concentration of 30% by mass was obtained.

[0161] (Production Example 9: Aqueous polyurethane resin dispersion A9)

[0162] In the above-mentioned methyl ethyl ketone solution, while adding 150 parts by mass of water in which 1.25 parts by mass of sodium hydroxide was dissolved at a rate of 6 parts by mass per minute (converted to 5.0×10 -2 parts by mass per minute in terms of the basic component), emulsification and dispersion were carried out using a homogenizer. Further, 150 parts by mass of water was added for emulsification and dispersion. In addition, by the same method as in Production Example 1, an aqueous polyurethane resin dispersion A9 having a solid content concentration of 30% by mass was obtained.

[0163] [Table 1]

[0164]

[0165] Table 1 shows the results of measuring D50 and D90 of the aqueous polyurethane resin dispersions obtained in each production example. The D50 of the aqueous polyurethane resin dispersions (A1, A2, A3, A4) obtained in Production Examples 1 to 4 was 0.01 μm or more and 0.05 μm or less, and the D90 was 0.10 μm or more and 0.15 μm or less.

[0166] (Example 1)

[0167] 8.5 parts by mass of an acetylene black aqueous dispersion (solid content concentration: 25% by mass) and 42.9 parts by mass of an SWCNT aqueous dispersion (solid content concentration: 1.0% by mass) were mixed and stirred for 1 hour. Then, 48.6 parts by mass of the aqueous polyurethane resin dispersion A1 (solid content concentration: 30% by mass) obtained in Production Example 1 was added thereto, and the mixture was stirred for 30 minutes to obtain a mixed solution. After stirring the mixed solution and 77.4 parts by mass of an aqueous carboxymethyl cellulose solution (solid content concentration: 1.0%) for 10 minutes using a homogenizing disperser, 153.2 parts by mass of an active substance (SiO) was added and stirred for 10 minutes using a homogenizing disperser. Finally, 11.6 parts by mass of water was added while stirring to prepare a solid content, and an electrode coating liquid composition having a solid content concentration of 50% by mass was obtained.

[0168] (Example 2)

[0169] The polyurethane resin aqueous dispersion A1 was changed to the polyurethane resin aqueous dispersion A2 (solid content concentration: 30% by mass) obtained in Production Example 2. Otherwise, an electrode coating liquid composition with a solid content concentration of 50% by mass was obtained in the same manner as in Example 1.

[0170] (Example 3)

[0171] The polyurethane resin aqueous dispersion A1 was changed to the polyurethane resin aqueous dispersion A3 (solid content concentration: 30% by mass) obtained in Production Example 3. Otherwise, an electrode coating liquid composition with a solid content concentration of 50% by mass was obtained in the same manner as in Example 1.

[0172] (Example 4)

[0173] The polyurethane resin aqueous dispersion A1 was changed to the polyurethane resin aqueous dispersion A4 (solid content concentration: 30% by mass) obtained in Production Example 4. Otherwise, an electrode coating liquid composition with a solid content concentration of 50% by mass was obtained in the same manner as in Example 1.

[0174] (Comparative Example 1)

[0175] The polyurethane resin aqueous dispersion A1 was changed to the polyurethane resin aqueous dispersion A5 (solid content concentration: 30% by mass) obtained in Production Example 5. Otherwise, an electrode coating liquid composition with a solid content concentration of 50% by mass was obtained in the same manner as in Example 1.

[0176] (Comparative Example 4)

[0177] The polyurethane resin aqueous dispersion A1 was changed to the polyurethane resin aqueous dispersion A8 (solid content concentration: 30% by mass) obtained in Production Example 8. Otherwise, an electrode coating liquid composition with a solid content concentration of 50% by mass was obtained in the same manner as in Example 1.

[0178] (Comparative Example 5)

[0179] The polyurethane resin aqueous dispersion A1 was changed to the polyurethane resin aqueous dispersion A9 (solid content concentration: 30% by mass) obtained in Production Example 9. Otherwise, an electrode coating liquid composition with a solid content concentration of 50% by mass was obtained in the same manner as in Example 1.

[0180] [Table 2]

[0181]

[0182] Table 2 shows the viscosities of the coating liquid compositions for electrodes prepared in each of the examples and comparative examples at each solid component. From the results in Table 2, it can be seen that the increase in the viscosity of the coating liquid compositions for electrodes prepared in the examples is suppressed. In particular, even when the solid component concentration is 50% by mass, its viscosity is at the level of the low solid component concentration range of the coating liquid compositions for electrodes in the comparative examples. That is, the coating liquid compositions for electrodes prepared in each of the examples can suppress the increase in the viscosity of the coating liquid for forming electrodes, and even when the solid component concentration of the coating liquid is increased, the viscosity is not likely to increase. Therefore, it is shown that the binder composition for electrodes of the present invention is suitable for preparing a coating liquid with a high solid component concentration and is suitable as a binder component (binder) for the coating liquid composition for electrodes used to fabricate electrodes of an electrical storage device.

Claims

1. An adhesive composition for an electrode, characterized in that: it contains a polyurethane resin aqueous dispersion, the D50 volume average particle diameter of the polyurethane resin is 0.01 μm or more and 0.05 μm or less, and the D90 volume average particle diameter is 0.10 μm or more and 0.15 μm or less.

2. The adhesive composition for an electrode according to claim 1, wherein: the adhesive composition for an electrode contains carbon nanotubes.

3. The adhesive composition for an electrode according to claim 2, wherein: the adhesive composition for an electrode contains carboxymethyl cellulose or a salt thereof.

4. A coating liquid composition for an electrode, characterized in that: it contains the adhesive composition for an electrode according to any one of claims 1 to 3.

5. An electrode for an electricity storage device, characterized in that ， It contains the solid component of the coating liquid composition for an electrode according to claim 4.

6. An electrical energy storage device, characterized in that: it includes an electrode for an electrical energy storage device according to claim 5.

7. A method for manufacturing an adhesive composition for an electrode, characterized in that: the adhesive composition for an electrode contains a polyurethane resin aqueous dispersion, the manufacturing method includes a step of preparing a polyurethane resin aqueous dispersion having a D50 volume average particle diameter of 0.01 μm or more and 0.05 μm or less and a D90 volume average particle diameter of 0.10 μm or more and 0.15 μm or less.

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