JP2012151108A - Electrochemical cell acrylic water dispersion and aqueous paste and manufacturing method of electrode and battery consisting of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder used in an electrochemical cell aqueous paste which has sufficient adhesion for a metal current collector and also is electrochemically stable so that an electrochemical cell does not easily swell and maintains conventional electrostatic capacitance and internal resistance, making it possible to improve cycle characteristics of especially a secondary battery.SOLUTION: An acrylic water dispersion for electrochemical cells includes a water soluble resin (a) obtained by polymerizing a monomer group containing at least a polymerizable monomer of unsaturated carboxylic acid or the like and (meta) acrylamide and organic particles (b) (however, except for the water soluble resin (a)). The acrylic water dispersion of the present invention has sufficient adhesion for metal current collectors, conductive assistants, cathode active materials and anode active materials and, when applied for batteries, is electrochemically stable so that an electrochemical cell does not easily swell, making it possible to improve cycle characteristics of especially a secondary battery.

Description

The present invention relates to a specific acrylic aqueous dispersion for use in an electrochemical cell.
The present invention also provides secondary batteries, for example, alkaline secondary batteries (Ni-MH batteries) obtained using hydrogen storage alloys, nonaqueous electrolyte secondary batteries (lithium ion batteries) obtained using lithium compounds. The present invention relates to an aqueous paste for an electrochemical cell that constitutes an electricity storage device such as an electric double layer capacitor.

  In the Ni-MH battery, the lithium ion battery, and the capacitor, each electrode is formed by binding each active material for positive electrode and negative electrode and a conductive additive to each current collector with a binder. The positive electrode binder is required to have oxidation resistance, and a solution in which polyvinylidene fluoride (PVDF) is dissolved in N-methyl-2-pyrrolidone (NMP) or fluorine-containing water of polytetrafluoroethylene (PTFE). A dispersion is used. In addition to PVDF, styrene-butadiene rubber (SBR) aqueous dispersion is used as a binder for the negative electrode.

  However, the positive electrode binder has oxidation resistance but is inferior in adhesion to the active material and current collector, so a large amount of addition is necessary. Therefore, there is a problem that the active material is coated to deteriorate the battery characteristics. SBR, which is sometimes used as a binder for negative electrodes, has a relatively high adhesion and requires a small number of blended parts. However, like PDVF, SBR has a high affinity with the electrolyte, so the battery should be left at high temperature. In addition, when charging and discharging are repeated, the resin swells, so that there is a problem that the battery tends to swell.

  Therefore, in order to solve these problems, studies have been made to use an aqueous dispersion of an olefin copolymer that is electrochemically stable and less swelled with respect to the electrolytic solution as a binder (Patent Documents 1 and 2). And 3). These binders are excellent in redox resistance, have a small swelling with respect to the electrolytic solution, and are difficult to cover the active material.

However, since the adhesiveness is relatively weak compared to SBR, there is a problem that the cycle characteristics, which is one of the important characteristics of the battery, are not sufficient.
In addition, each compounded composition contained in the aqueous paste for electrochemical cells may be replaced with another substance selected from a similar substance group or fine adjustment of the compounding composition ratio in order to correspond to various usage situations and applications. is there. With such a change in the blending composition, the blending stability and performance of the binder are adversely affected. Therefore, it is necessary to optimize the composition constituting the binder. However, in the case of an olefin copolymer, there is a problem that the degree of freedom of the composition is low.

  Patent Documents 4 and 5 disclose battery binder compositions containing latex. In the latex, an olefin copolymer is used as polymer particles.

  However, the latex has a problem in coating properties and adhesion to the positive electrode or negative electrode of the battery, and the film thickness of the coating film cannot be increased. Therefore, there has been a problem that the capacitance of the electrochemical cell cannot be increased.

JP-A-9-251856 JP 2009-110883 A JP 2010-189632 A JP-A-11-149929 International Publication No. 1998/39808

  The present invention seeks to solve the problems associated with the prior art as described above, has sufficient adhesion to a metal current collector, is electrochemically stable, and has an expanded electrochemical cell. It is difficult to provide a binder for use in an aqueous paste for an electrochemical cell that can improve the cycle characteristics of a secondary battery while maintaining the conventional electrostatic capacity and internal resistance.

  Moreover, it is providing the battery with the high cycle life by charging / discharging containing the electrode plate for electrochemical cells obtained using the aqueous paste for electrochemical cells containing a specific acrylic water dispersion, and this electrode plate.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a specific acrylic water dispersion. That is,
The acrylic water dispersion for electrochemical cells of the present invention is a water-soluble resin (a) obtained by polymerizing a monomer group containing at least a polymerizable monomer of an unsaturated carboxylic acid and (meth) acrylamide. And organic particles (b) (excluding the water-soluble resin (a)).

Moreover, it is preferable that the polymerizable monomer of the unsaturated carboxylic acid contains substantially no dicarboxylic acid but contains a monocarboxylic acid.
It is preferable that the polymerizable monomer of the unsaturated carboxylic acid does not substantially contain a conjugated diene monomer.

The organic particles (b) are preferably particles obtained by polymerizing one or more vinyl monomers in the presence of the water-soluble resin (a).
The water-soluble resin (a) is preferably a resin obtained by polymerization in the presence of organic particles (b) obtained by polymerizing one or more kinds of vinyl monomers.

It is preferable that the water-soluble resin (a) and the organic particles (b) are mixed.
The weight ratio of the water-soluble resin (a) to the organic particles (b) is (a) 10 to 90% by weight and (b) 90 to 10% by weight (however, the sum of (a) and (b) is 100). It is preferable that the weight is%.

The pH of the aqueous dispersion is preferably in the range of 7 to 11.
The aqueous dispersion preferably further contains at least one selected from a surfactant (x) and a viscosity modifier (y).

The aqueous paste for electrochemical cells of the present invention comprises an acrylic aqueous dispersion for electrochemical cells, and at least one selected from an active material (B) and a conductive additive (C).
The aqueous paste for electrochemical cells preferably contains 0 to 40 parts by weight of an organic solvent with respect to 100 parts by weight of water contained in the acrylic aqueous dispersion for electrochemical cells.

The electrode plate for electrochemical cells of the present invention is obtained using an aqueous paste for electrochemical cells.
The secondary battery of this invention is obtained using the electrode for electrochemical cells.

  The specific acrylic aqueous dispersion of the present invention has sufficient adhesion to a metal current collector, a conductive additive, a positive electrode active material, and a negative electrode active material, and is electrochemical when applied to a battery. And the electrochemical cell is less likely to swell, and in particular, the cycle characteristics of the secondary battery can be improved.

Electrodes can be efficiently produced by using the aqueous paste for electrochemical cells of the present invention.
Moreover, the battery containing the electrode plate obtained by using the aqueous paste for electrochemical cells has a high cycle life due to charge and discharge.

  Therefore, it is possible to obtain a highly efficient battery that is reduced in size, weight, and capacity.

[Acrylic water dispersion for electrochemical cells]
The acrylic aqueous dispersion for electrochemical cells according to the present invention is an emulsion in which an acrylic copolymer is dispersed in water. This emulsion comprises a water-soluble resin (a) obtained by polymerizing a monomer group containing at least a polymerizable monomer of an unsaturated carboxylic acid and (meth) acrylamide, and one or more vinyl monomers. It contains organic particles (b) obtained by emulsion polymerization of the body. Here, (meth) acrylamide means methacrylamide and acrylamide. The organic particles (b) are different from the water-soluble resin (a).

  The water-soluble resin in the present invention is defined as a resin having a transmittance of 85% or more of light having a wavelength of 400 nm at a concentration of 10% by weight in a medium mainly composed of water. It means a resin that forms a particulate form in a medium mainly composed of the above and has a light transmittance of 85% or less at a wavelength of 400 nm at a concentration of 10% by weight.

The pH of the acrylic water dispersion is preferably in the range of 7 to 11 from the viewpoint of preventing corrosion of the metal electrode plate.
The acrylic water dispersion may be present in any form of the water-soluble resin (a) and the organic particles (b), and is a resin composition obtained by separately synthesizing and mixing (a) and (b). Both the form, the form of the resin composition obtained by polymerizing in the presence of (b), and the form of the resin composition obtained by polymerizing in the presence of (a) (b) are the present invention. Is within the range.

  From the viewpoint of storage stability of the aqueous dispersion, the form of a resin composition obtained by synthesizing one resin in the presence of either the resin (a) or (b) is preferable. Furthermore, it is more preferable that (b) is in the form of a resin composition obtained by polymerization in the presence of (a).

  The weight ratio of the water-soluble resin (a) and the organic particles (b) is not particularly limited, but preferably (a) is 10 to 90% by weight and (b) is 90 to 10% by weight, more preferably (a). Is 30 to 70% by weight and (b) is 70 to 30% by weight (provided that the sum of (a) and (b) is 100% by weight). If (a) is 10% by weight or less, dispersion stability and adhesion may be insufficient, and if it is 90% by weight or more, remarkable thixotropy characteristics may be produced.

  The volume average particle size of the acrylic aqueous dispersion according to the present invention is not particularly limited, but is usually 10 to 1,000 nm, preferably 10 to 800 nm (particle size analyzer FPAR-1000 (Otsuka Electronics Co., Ltd.)). Is preferable because it is excellent in water dispersion stability. If the thickness is less than 10 nm, the dispersion stability may be lowered, and if it exceeds 1,000 nm, the storage stability with time may be impaired. The method for controlling the particle size is not particularly limited, but can be appropriately adjusted depending on, for example, the amount of the surfactant.

The particle diameter of the polymer particles can be measured by observation with an electron microscope, a Coulter counter, or a light scattering method. For example, with Coulter counter, Coulter counter N4 (manufactured by Coulter), and with light scattering method, particle size analyzer FPAR-1000 (Otsuka Electronics Co., Ltd.), laser particle size analysis system LPA-3000 / 3100 (Otsuka Electronics Co., Ltd.), laser It can be measured with a diffraction particle size distribution analyzer SALD-2000A (Shimadzu Corporation).
The resin solid content concentration of the acrylic aqueous dispersion according to the present invention is 5 to 80% by weight, preferably 10 to 70% by weight. Within this range, good electrode plate adhesion can be obtained.

Water-soluble resin (a)
The water-soluble resin (a) of the present invention is a resin obtained by polymerizing a monomer group containing at least a polymerizable monomer of an unsaturated carboxylic acid and (meth) acrylamide.

  In the present invention, both methacrylamide and acrylamide may be used, and methacrylamide is preferably used from the viewpoint of adjusting the viscosity of the aqueous dispersion and the aqueous paste using the same.

  Examples of polymerizable monomers for unsaturated carboxylic acids include monocarboxylic acids such as acrylic acid and methacrylic acid, and dicarboxylic acids such as itaconic acid, maleic acid, fumaric acid, maleic anhydride, itaconic anhydride, and fumaric anhydride. It is done. Further, for example, these salts such as lithium salt, potassium salt, sodium salt, ammonium salt may be used, and derivatives of these acids can also be used as appropriate. As the salt, a lithium salt is preferable. The polymerizable monomers of unsaturated carboxylic acids can be used alone or in combination of two or more.

  Among these, monocarboxylic acids such as acrylic acid and methacrylic acid are easy to introduce into the water-soluble resin (a) with little restriction in the polymerization process because they exhibit good compatibility with a wide range of vinyl monomers. Therefore, it is preferable. Maleic acid, fumaric acid and the like, which are dicarboxylic acids, tend to be inferior in copolymerizability with acrylic acid esters and methacrylic acid esters described later, compared to monocarboxylic acids such as acrylic acid and methacrylic acid. Therefore, unreacted monomers may remain in the aqueous paste for electrochemical cells, and there is a concern that battery characteristics such as capacity reduction may be adversely affected. Therefore, in the present invention, the polymerizable monomer for unsaturated carboxylic acids preferably contains substantially no dicarboxylic acids and monocarboxylic acids. Here, “substantially free” means that the dicarboxylic acids are preferably 10% by weight or less, more preferably 5% with respect to 100% by weight of the total monomers constituting the water-soluble resin (a). % By weight or less, more preferably 0% by weight. The dicarboxylic acids can be measured by, for example, infrared absorption analysis, (thermal decomposition) gas chromatograph mass spectrometry, or nuclear magnetic resonance analysis. Moreover, the said 0 weight% means that it is below a detection limit, for example when it measures by these analysis methods.

Moreover, as a polymerizable monomer of unsaturated carboxylic acids, methacrylic acid is preferable.
The water-soluble resin (a) of the present invention may polymerize one or more other vinyl monomers together with a polymerizable monomer of an unsaturated carboxylic acid and (meth) acrylamide. Here, the one or more vinyl monomers are preferably vinyl monomers having a functional group, for example, an amide group-containing vinyl monomer other than acrylamide, and a hydroxyl group such as 2-hydroxyethyl (meth) acrylate. Vinyl monomers, glycidyl group-containing vinyl monomers such as glycidyl (meth) acrylate, cyano group-containing vinyl monomers such as (meth) acrylonitrile, and amino groups such as N, N-dimethylaminoethyl (meth) acrylate Examples thereof include vinyl monomers, acetoacetoxy group-containing vinyl monomers such as acetoacetoxyethyl (meth) acrylate, and sulfonic acid-containing monomers such as sodium styrenesulfonate and sodium methallylsulfonate. Moreover, you may use hydrophobic vinyl monomers, such as (meth) acrylic acid ester, such as styrene and methyl acrylate. Further, a crosslinkable vinyl monomer may be used for the water-soluble resin (a), and examples of the monomer include methylene bis (meth) acrylamide, divinylbenzene, polyethylene glycol chain-containing di (meth) acrylate, and the like. It can be illustrated. Moreover, you may contain a 2 or more vinyl group as a crosslinkable vinyl monomer.

  In the present invention, as one or more other vinyl monomers, conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, piperylene Etc. are preferably substantially not contained. Here, “substantially free” is preferably 10% by weight or less, more preferably 5% by weight or less, still more preferably 100% by weight of the total amount of monomers constituting the water-soluble resin (a). Is 0% by weight. When the water-soluble resin (a) contains substantially no conjugated diene monomer, oxidation resistance tends to be obtained particularly when used on the positive electrode side. The conjugated diene monomer in the water-soluble resin can be measured, for example, by infrared absorption analysis, (thermal decomposition) gas chromatograph mass spectrometry, or nuclear magnetic resonance analysis. Moreover, the said 0 weight% means that it is below a detection limit, for example when it measures by these analysis methods.

Moreover, you may use molecular weight regulators, such as n-dodecyl mercaptan and 1-thioglycerol, in order to adjust the molecular weight of water-soluble resin (a).
The water-soluble resin (a) is not particularly limited, but the total of the polymerizable monomers of carboxylic acids and (meth) acrylamide is usually 100 to 10% by weight, preferably 100% by weight of the total monomer group. When it contains 100 to 50% by weight, more preferably 100 to 60% by weight, and other vinyl monomers, it is usually 0 to 90% by weight, preferably 0 to 50% in 100% by weight of the monomer group. % By weight, more preferably 0 to 40% by weight.

  In the water-soluble resin (a), the weight ratio of (meth) acrylamide to the polymerizable monomer of unsaturated carboxylic acid is 50 to 99 weight percent of (meth) acrylamide from the viewpoint of adhesion to the electrode plate. %, Preferably 60 to 95% by weight, 1 to 50% by weight of polymerizable monomer of unsaturated carboxylic acid, preferably 5 to 40% by weight (however, polymerization of (meth) acrylamide and unsaturated carboxylic acid) The total of the monomer is 100% by weight).

Production Method of Water-Soluble Resin (a) The method for synthesizing the water-soluble resin (a) is not particularly limited, but polymerization performed in a solvent containing water as a main component is preferable. A particularly preferred polymerization form is aqueous solution polymerization. Although there is no restriction | limiting in the polymerization initiator at the time of the synthesis | combination of water-soluble resin (a), A water-soluble radical initiator is preferable, persulfates, such as ammonium persulfate, 4,4'- azobis (4-cyanovaleric acid), etc. The water-soluble azo initiator is particularly preferred. Although the usage-amount of a polymerization initiator is not specifically limited, It is 0.1 to 5 weight% normally on the basis of the total weight of the monomer to (co) polymerize.

  Resin (a) The polymerization temperature at the time of synthesis is not limited, but it should be synthesized in the range of 30 to 95 ° C taking into account the production time and the conversion rate of the monomer to the copolymer (reaction rate). Is preferable, and 50-85 degreeC is especially preferable. Moreover, at the time of superposition | polymerization, it is also possible to use PH preparation agent, EDTA which is a metal ion sealing agent, its salt, etc. in order to improve manufacturing stability.

  Also, for example, before polymerization of the water-soluble resin (a) or the organic particles (b), when the water-soluble resin (A) is water-solubilized, after the formation of the organic resin (b), or a copolymer emulsion (acrylic water dispersion) After the formation, the pH may be adjusted with a general neutralizing agent such as ammonia, organic amine, potassium hydroxide, sodium hydroxide or lithium hydroxide. As the neutralizing agent, it is preferable to adjust the pH within the range of 7 to 11 with ammonia (water) from the viewpoint of substrate corrosion. In addition, neutralization can be suitably performed in the adjustment process of the acrylic water dispersion.

Organic particles (b)
The organic particles (b) (excluding the water-soluble resin (a)) is preferably a (co) polymer emulsion obtained by emulsion polymerization of one or more vinyl monomers. As vinyl monomers, aromatic vinyl monomers, acrylic esters, methacrylic esters, unsaturated carboxylic acids, unsaturated sulfonic acids, hydroxyl group-containing vinyl compounds, aromatic vinyl compounds, unsaturated amides, amino Alkyl acrylates or aminoalkyl methacrylates, or quaternary chlorides thereof, such as methyl halides, ethyl halides, benzyl halides, N-aminoalkylacrylamides or N-aminoalkylmethacrylamides, or methyl halides thereof, Examples include quaternary chlorides, vinyl esters, vinylidene halides, diacrylates, dimethacrylates, and the like with ethyl halide, benzyl halide, and the like.

These vinyl monomers can be used alone or in combination of two or more.
Examples of the aromatic vinyl monomer include styrene, p-methylstyrene, α-methylstyrene, 2-methylstyrene, t-butylstyrene, chlorostyrene, vinylxylene, vinylnaphthalene, vinylanthracene and vinylanisole.

  Acrylic acid esters include alkyl esters of acrylic acid having 1 to 12 carbon atoms, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-amyl acrylate, isoamyl acrylate, Examples include n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, and benzyl acrylate.

  Methacrylic acid esters include methacrylic acid alkyl ester having 1 to 12 carbon atoms, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl. Methacrylate, 21-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate and the like.

  Examples of unsaturated carboxylic acids include monocarboxylic acids such as acrylic acid and methacrylic acid, and dicarboxylic acids such as itaconic acid, maleic acid, fumaric acid, maleic anhydride, itaconic anhydride, and fumaric anhydride. Further, for example, these salts such as lithium salt, potassium salt, sodium salt, ammonium salt may be used, and derivatives of these acids can also be used as appropriate. As the salt, a lithium salt is preferable.

  Among these, monocarboxylic acids such as acrylic acid and methacrylic acid are easy to introduce into the organic particles (b) because they have good compatibility with a wide range of vinyl monomers and have few restrictions in the polymerization process. Is preferred. In addition, when acrylic acid esters or methacrylic acid esters are used as vinyl monomers, dicarboxylic acids such as maleic acid and fumaric acid are used in the same manner as the water-soluble resin (a). The copolymerizability tends to be inferior to monocarboxylic acids such as. Therefore, unreacted monomers may remain in the aqueous paste for electrochemical cells, and there is a concern that battery characteristics such as capacity reduction may be adversely affected. Therefore, in the present invention, the polymerizable monomer for unsaturated carboxylic acids preferably contains substantially no dicarboxylic acids and monocarboxylic acids. “Substantially free” means that the dicarboxylic acids are preferably 10% by weight or less, more preferably 5% by weight or less, with respect to 100% by weight of the total monomers constituting the organic particles (b). More preferably, it is 0% by weight. The dicarboxylic acids in the organic particles can be measured by the same method as described in the water-soluble resin (a). The same applies to the above 0% by weight.

Examples of the unsaturated sulfonic acids include 2-sulfoethyl methacrylate, t-butyl acrylamide sulfonic acid, styrene sulfonic acid, and salts thereof.
Examples of hydroxyl-containing vinyl compounds include 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, polyethylene glycol monomethacrylate, polypropylene Examples include glycol monomethacrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, and glycerol monomethacrylate.

  As unsaturated amides, acrylamide, methacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N-methylol Examples include methacrylamide, N-methylol acrylamide, diacetone acrylamide, and maleic amide.

  As aminoalkyl acrylates or aminoalkyl methacrylates, N, N-dimethylaminoethyl acrylate, N, N-dimethylaminoethyl methacrylate, N, N-dimethylaminopropyl acrylate, N, N-dimethylaminopropyl methacrylate, N, N -T-butylaminoethyl acrylate, N, N-t-butylaminoethyl methacrylate, N, N-monomethylaminoethyl acrylate, N, N-monomethylaminoethyl methacrylate and the like can be mentioned.

  Examples of N-aminoalkyl acrylamide or N monoaminoalkyl methacrylamide include N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, N, N-dimethylaminoethyl acrylamide, N, N- And dimethylaminoethyl methacrylamide.

Examples of vinyl esters include vinyl acetate and vinyl propionate.
Examples of vinylidene halides include vinylidene chloride and vinylidene fluoride.

  Examples of diacrylates include polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol diacrylate, and polypropylene glycol diacrylate.

  Dimethacrylates include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6- Hexanediol dimethacrylate, neopentyl glycol dimethacrylate and the like can be mentioned.

  Other monomers include trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethane triacrylate, tetramethylolmethane tetraacrylate, allyl medaacrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, vinyl chloride, Vinyl ether, vinyl ketone, vinyl amide, chloroprene, ethylene, propylene, isoprene, butadiene, vinyl pyrrolidone, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, acrylonitrile, methacrylonitrile, isopropenyl- α, α-dimethylbenzyl isocyanate, ants Examples include lumercaptan.

  In the present invention, conjugated diene monomers such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, piperylene and the like are substantially not included as other monomers. It is preferable. Here, “substantially free” is preferably 10% by weight or less, more preferably 5% by weight or less, and still more preferably 100% by weight of the total vinyl monomers constituting the organic particles (b). Is 0% by weight. When the organic particles (b) contain substantially no conjugated diene monomer, oxidation resistance tends to be obtained particularly when used on the positive electrode side. The conjugated diene monomer in the organic particles can be measured by the same method as described in the water-soluble resin (a). The same applies to the above 0% by weight.

  Particularly suitable as the one or more vinyl monomers are monocarboxylic acids such as acrylic acid and methacrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, ethyl methacrylate, n -Butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylonitrile and the like. The monocarboxylic acids are particularly preferably acrylic acid and methacrylic acid.

  More preferably, the organic particles (b) contain 10 to 70% by weight of acrylonitrile with respect to 100% by weight of the total vinyl monomers constituting the organic particles (b) from the viewpoint of water resistance and solvent resistance. Better.

  If necessary, a crosslinkable vinyl monomer may be used. Examples of the monomer include methylene bis (meth) acrylamide, divinylbenzene, polyethylene glycol chain-containing di (meth) acrylate and the like. Moreover, you may contain a 2 or more vinyl group as a crosslinkable vinyl monomer.

For the purpose of adjusting the molecular weight, a molecular weight modifier such as n-dodecyl mercaptan or 1-thioglycerol can also be used.
The glass transition temperature Tg of the organic particles (b) is not particularly limited, but is preferably −30 to 80 ° C. (according to calculation software CHEOPS (ver. 4.0)) from the viewpoint of flexibility of the electrode plate. If it is less than −30 ° C., tack remains on the electrode plate, which is not preferable.

Production of organic particles (b) The method for synthesizing the organic particles (b) is not particularly limited, but emulsion polymerization carried out in a solvent containing water as a main component is preferred. For the purpose of improving the polymerization stability and storage stability of the organic particles (b), a surfactant (x) or a water-soluble polymer can be appropriately used. Examples of the surfactant (x) include anionic surfactants and nonionic surfactants.

  Examples of the anionic surfactant include dodecylbenzene sulfonate, lauryl sulfate, alkyl diphenyl ether disulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, stearate, oleate, dioctyl sulfosuccinate, Examples thereof include polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, dialkyl sulfosuccinate, tert-octylphenoxyethoxy polyethoxyethyl sulfate, and the like. Examples of the salt include ammonium salt, lithium salt, sodium salt and potassium salt.

  Nonionic surfactants include, for example, polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether, polyoxyalkylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene Styrenated phenyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene oleyl phenyl ether, polyoxyethylene nonyl phenyl ether, oxyethylene / oxypropylene block copolymer, t-octylphenoxyethyl polyethoxy Examples include ethanol and nonylphenoxyethyl polyethoxyethanol.

These dispersants (surfactants) can be selected from one or two or more.
Water-soluble polymers used for the purpose of improving polymerization stability and storage stability may be added. Examples of these water-soluble polymers include polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl pyrrolidone, (meth) Examples thereof include water-soluble polymers such as acrylic acid (co) polymers, poly (meth) acrylamide (co) polymers, and ethylene glycol.

These water-soluble polymers can be used alone or in combination of two or more.
Examples of the polymerization initiator include persulfates such as hydrogen peroxide and ammonium persulfate, azobiscyanovaleric acid, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- ( N-phenylamidino) propane] dihydrochloride, 2,2′-azobis {2- [N- (4-chlorophenyl) amidino] propane} dihydrochloride, 2,2′-azobis {2- [N- (4 -Hydroxyphenyl) amidino] propane} dihydrochloride, 2,2'-azobis [2- (N-benzylamidino) propane] dihydrochloride, 2,2'-azobis [2- (N-allylamidino) propane] Dihydrochloride, 2,2'-azobis {2- [N- (2-hydroxyethyl) amidino] propane} dihydrochloride, azobisisobutyronitrile, 2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxy Til] propionamide}, 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide}, 2,2′-azobis [2-methyl-N- [2 -Hydroxyethyl] propionamide], azo compounds such as 2,2′-azobis (isobutylamide) dihydrate; cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, t-butylperoxy-2 Organic peroxides such as -ethylhexanoate, t-butylperoxybenzoate, lauroyl peroxide, and the like can be used, and one or more of these can be selected.

The initiator is preferably water-soluble, and a general initiator is used in an amount of 0.1 to 5% by weight based on the total weight of the (co) polymerized monomer.
Although there is no restriction | limiting in the polymerization temperature at the time of the synthesis | combination of an organic particle (b), it synthesize | combines in the range of 30-95 degreeC when manufacturing time, the conversion rate (reaction rate) of a monomer into a copolymer are taken into consideration. It is preferable to carry out, and 50-85 degreeC is especially preferable.

Moreover, at the time of superposition | polymerization, it is also possible to use PH preparation agent, EDTA which is a metal ion sealing agent, its salt, etc. in order to improve manufacturing stability.
Moreover, you may adjust pH using a neutralizing agent. For neutralization, the above can be referred to.

  Various additives may be added to the acrylic aqueous dispersion of the present invention. The additive can be used before, during, or after polymerization. Examples of additives include pH adjusters, chelating agents, pigments, wetting agents, antistatic agents, antioxidants, preservatives, ultraviolet absorbers, light stabilizers, optical brighteners, colorants, penetrants, Examples include foaming agents, mold release agents, antifoaming agents, antifoaming agents, fluidity improving agents, and thickeners, but are not limited thereto. Various compounds can also be added to the acrylic copolymer binder of the present invention. As the compound, various oxidizing agents, water-soluble polymers such as polyacrylic acid, polyvinyl alcohol, polyethylene glycol and glucose, and substances such as surfactants may be added alone or in combination of two or more.

The addition amount and type are not particularly limited as long as the object of the present invention can be achieved.
The acrylic aqueous dispersion of the present invention can contain at least one selected from a surfactant (x) and a viscosity modifier (y).

Surfactant (x)
In the present invention, if necessary, surfactant (x) may be added as an emulsifier. The surfactant may be included in advance in the acrylic aqueous dispersion.

  The surfactant is a substance that modifies the hydrophilic or hydrophobic state of the substance surface or interface. In the present invention, the surfactant functions as a dispersant, a wetting agent, and an antifoaming agent. When this is contained, it is preferable at the point of the aqueous dispersion of an active material and a conductive support agent.

The surfactant is preferably an anionic surfactant and a nonionic surfactant exemplified above, or a silicon surfactant, but is not particularly limited.
Examples of the silicon-based surfactant include polydimethylsiloxane, polyether-modified polydimethylsiloxane, polymethylalkylsiloxane, and silicon-modified polyoxyethylene ether.

Only one type of surfactant may be used, or a plurality of these types may be used in combination.
Among these surfactants, potassium oleate and potassium stearate are preferable in that the active material and the conductive additive are dispersed in water. In addition, acetylenic glycol derivative polyoxyethylene ether and silicon-modified polyoxyethylene ether are preferable from the viewpoint of reducing the surface tension of water. As the surfactant, when at least one selected from potassium oleate, polyoxyethylene ether of an acetylenic glycol derivative and silicon-modified polyoxyethylene ether is used, the resulting aqueous dispersion is a good active material, conductive It is more preferable because a dispersion state of the auxiliary agent can be obtained.

  The addition amount of the surfactant is 0 to 100 parts by weight, preferably 3 to 80 parts by weight, in terms of solids, with respect to 100 parts by weight of the solids in the acrylic water dispersion. If this range is exceeded, the compatibility of the resin particles with the electrolyte will increase, and the strength will be significantly reduced, and the resin will easily swell.

Viscosity modifier (y)
In this invention, you may add a viscosity modifier (y) as needed. The viscosity modifier may be included in advance in the acrylic water dispersion.

  The aqueous paste for electrochemical cells (ink for applying a positive electrode, a negative electrode active material, and a conductive additive to a current collector) of the present invention preferably contains a viscosity modifier. Since the acrylic water dispersion according to the present invention is a water dispersion type, when a viscosity modifier is used, an optimum viscosity can be imparted to the electrode paste, and the electrode paste can be easily applied to the electrode.

  When a viscosity modifier is blended, it is possible to prevent the active material and the conductive aid from sinking and separating over time when the paste is allowed to stand. Furthermore, when the volume average particle diameter of the acrylic copolymer according to the present invention is larger than 200 nm, it is preferable because separation and sedimentation with time can be improved.

  The addition amount of the viscosity modifier is not particularly limited, but is preferably 10 to 100 parts by weight in terms of solid content with respect to 100 parts by weight of the solid content of the acrylic copolymer from the viewpoint of coating properties and workability. More preferably, it is 10 to 95 parts by weight.

  Although a viscosity modifier is not specifically limited, The weight average molecular weight calculated | required by GPC becomes like this. Preferably it is 50,000-4,000,000 (polystyrene conversion), More preferably, it is 60,000-3, 500,000, More preferably Is 65,000-3,000,000. If the weight average molecular weight is less than 50,000, the active material may be precipitated, and if it exceeds 4,000,000, the paste may have remarkable thixotropic characteristics. Moreover, it is preferable that it is in the above-mentioned range since good electrode plate coatability can be obtained.

  Although it does not specifically limit as a viscosity modifier, Cellulose derivatives, such as carboxymethylcellulose (CMC), carboxyethylcellulose, and hydroxyethylcellulose, polyoxyethylene or its modified body, polyvinyl alcohol or its modified body, polysaccharide, etc. are mentioned.

Among these viscosity modifiers, CMC, polyoxyethylene or a modified product thereof, polyvinyl alcohol or a modified product thereof is more preferable from the viewpoint of sedimentation stability.
Only one type of viscosity modifier may be used, or a plurality of these types may be used in combination.

Organic Solvent In the present invention, an organic solvent may be added as necessary. The organic solvent may be included in advance in the acrylic aqueous dispersion.

  Since the aqueous paste for electrochemical cells according to the present invention is a solvent mainly composed of water having a high surface tension, the wettability of the surface of the active agent or the conductive aid may be insufficient, resulting in poor dispersion during blending. By adding an organic solvent whose surface tension is lower than that of water, the wettability of the substance surface or interface can be improved, and the affinity between the solvent and the solute can be improved. This is preferable. In the present invention, the organic solvent serves not only as a wetting agent but also as an antifoaming agent.

  Although it does not specifically limit as an organic solvent, C1-C4 alkyl alcohols, such as n-butanol, isobutanol, 2-butanol, propanol, isopropanol, N-methyl-2-pyrrolidone, etc. are mentioned, Organic solvents may be used in combination, and it is preferable to adjust the SP value according to the formulation.

  When adding an organic solvent, the addition amount is 0-40 weight part normally with respect to 100 weight part of water contained in the acrylic water dispersion which concerns on this invention from a safety viewpoint, Preferably it is 0-30. Parts by weight.

<Aqueous paste for electrochemical cells>
The aqueous paste for electrochemical cells of the present invention contains at least one selected from the acrylic aqueous dispersion, the active material (B), and the conductive additive (C) of the present invention.

[Active material (B)]
The active material (B), but are not limited to, natural graphite as a negative electrode, artificial graphite, as the positive electrode and the like _{LiCoO 2, LiMn 2 O 4,} LiFePO 4. Moreover, you may use the carbon material of a conductive support agent suitably.

  For example, the negative electrode active material for a lithium ion secondary battery is not particularly limited as long as it can be doped / undoped with lithium ions. Metal lithium, lithium alloy, tin oxide, niobium oxide, vanadium oxide, titanium oxide, silicon Carbon materials such as transition metal nitrides and natural graphite, and composites thereof can be used.

The positive electrode active material for lithium ion secondary batteries, Li ₂ S, sulfur compounds such as _{S, LiCoO 2, LiMnO 2,} LiMn 2 O 4, LiNiO 2, LiNi X Co (1-X) O 2, LiNi x _{Mn y Co (1-xy)} , LiNi x Co y Al (1-xy), Li 2 MnO 3, a composite oxide consisting of lithium, such as a transition metal, LiFePO _4, phosphate compounds such LiMnPO _4, polyaniline, Examples thereof include conductive polymer materials such as polythiophene, polypyrrole, polyacetylene, polyacene, and dimercaptothiadiazole / polyaniline complex. Of these, composite oxides composed of lithium and a transition metal and phosphoric acid compounds such as LiFePO ₄ and LiMnPO ₄ are particularly preferable. When the negative electrode is lithium metal or a lithium alloy, a carbon material can also be used as the positive electrode. As the positive electrode, a mixture of lithium and transition metal composite oxide and a carbon material can be used.

  Taking a nickel metal hydride secondary battery as an example of the alkaline secondary battery, nickel hydroxide, a composite of nickel hydroxide, cobalt, or zinc can be used as the positive electrode active material.

Examples of the negative electrode active material include hydrogen storage alloys made of manganese, nickel, cobalt, aluminum, misch metal, and the like.
Various activated carbons are used as positive and negative electrode active materials for electric double layer capacitors.
The solid content of the acrylic aqueous dispersion of the present invention is usually 0.5 to 200 parts by weight, preferably 0.5 to 120 parts by weight with respect to 100 parts by weight of (B).

[Conductive aid (C)]
The conductive additive (C) is not particularly limited, but carbon materials such as carbon black, amorphous whisker carbon, graphite, acetylene black and artificial graphite, conductive polymers such as polythiophene and polypyrrole and derivatives thereof, and metal fine particles such as cobalt. Etc. These may be used singly or in combination of two or more. You may use the carbon material of an active material suitably.

  A conductive support agent is 0.1-200 weight part normally with respect to 100 weight part of active materials, Preferably it is 0.1-120 weight part. Within this range, good lithium ion transportability and electrical conductivity can be obtained without impairing the charge capacity. Moreover, there exists a possibility of increasing the electrical resistance of a compound-material layer as it is less than 0.1 weight part.

  When the aqueous paste of the present invention is used as a current collector, the active material (B) is unnecessary and the conductive auxiliary agent (C) may be used alone. In this case, the amount of (C) used is 50 to 200 parts by weight with respect to 100 parts by weight of the solid content of the aqueous dispersion.

[Production of electrochemical cell]
In one embodiment of the present invention, an electrode for an electrochemical cell according to the present invention comprises an acrylic aqueous dispersion for an electrochemical cell according to the present invention and a conductive auxiliary agent, preferably a carbon material such as carbon black, amorphous whisker carbon, or graphite. And / or using a positive electrode active material for the positive electrode and a negative electrode active material for the negative electrode.

  Moreover, in one aspect of the present invention, among the electrochemical cells of the present invention, the secondary battery is a cylinder, coin, square, or film type in which the positive electrode and the negative electrode are stacked with a separator as a center. In addition, it is formed in any shape and encapsulating a non-aqueous electrolyte.

In addition, the electric double layer capacitor is formed by forming the above-described electrode on the separator center in an arbitrary shape such as a cylindrical shape or a coin shape and enclosing an electrolytic solution.
As the separator, a porous membrane or a polymer electrolyte is used in the secondary battery. Examples of the porous membrane include polyolefin, polyimide, polyvinylidene fluoride, and polyester. In particular, a porous polyolefin film is preferable, and specifically, a porous polyethylene film, a porous polypropylene film, or a multilayer film of a porous polyethylene film and polypropylene can be exemplified. On the porous polyolefin film, other resin excellent in thermal stability may be coated.

In the electric double layer capacitor, in addition to the separator similar to the secondary battery, electrolytic capacitor paper, a porous film containing inorganic ceramic powder, or the like can be used.
In the secondary battery, as the non-aqueous electrolyte solution such as lithium ion, for example, an electrolyte such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) N / Li is used alone. Or a combination of two or more of them dissolved in an organic solvent can be used.

As an alkaline electrolyte such as nickel hydride, for example, an aqueous solution obtained by combining electrolytes such as potassium hydroxide and sodium hydroxide alone or in combination can be used.
In the electric double layer capacitor, any electrolyte can be used. However, the non-aqueous electrolyte is an organic electrolyte formed by combining tetraethylammonium tetrafluoroborate, triethylmonomethylammonium tetrafluoroborate, etc. singly or in combination of two or more kinds as electrolytes. What was melt | dissolved in the solvent can be used.

  In the non-aqueous secondary battery and the electric double layer capacitor, examples of the organic solvent in the non-aqueous electrolyte include propylene carbonate, ethylene carbonate, γ-butyrolactone, dimethyl sulfoxide, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, 1,2 -Dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran and the like can be mentioned, any of which can be used alone or in admixture of two or more.

[Precoat agent for electrode plate for electrochemical cells]
The acrylic aqueous dispersion for an electrochemical cell of the present invention can also be used as a precoat agent for an electrode plate for an electrochemical cell. The precoat agent is selected from the acrylic aqueous dispersion for electrochemical cells of the present invention alone or the acrylic aqueous dispersion for electrochemical cells of the present invention, the active material (B), and the conductive additive (C). Including at least one kind, effects such as prevention of substrate corrosion can be obtained by pre-coating (pre-coating) the pre-coating agent on an electrode plate (for example, negative electrode: copper, positive electrode: aluminum) in an electrochemical cell. . In addition, as a precoat agent, the acrylic water dispersion of this invention and a conductive support agent (C) are included, or the acrylic water dispersion of this invention, an active material (B), and a conductive support agent (C) are included. Those are preferred.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

<Preparation of aqueous dispersion>
Production Example 1
<Synthesis of water-soluble resin (a)>
A separable flask equipped with a stirrer and reflux cooling was charged with 200 parts by weight of distilled water, replaced with nitrogen gas, and then heated to 80 ° C. Next, 2.0 parts of ammonium persulfate was added, and a mixture of the vinyl monomer and water having the following composition was continuously added over 2 hours with stirring, and then aged for 2 hours at the same temperature. The pH was adjusted to 9.0 to complete the polymerization. An aqueous liquid of resin (a) having a solid content of 20.0% was obtained.
(Mixture of vinyl monomer and water)
Methacrylamide 65.0 parts Methacrylic acid 10.0 parts 2-Hydroxyethyl methacrylate 20.0 parts Methyl acrylate 5.0 parts Distilled water 210.0 parts

Production Example 2
<Synthesis of water-soluble resin (a)>
A separable flask equipped with a stirrer and reflux cooling was charged with 200 parts by weight of distilled water, replaced with nitrogen gas, and then heated to 80 ° C. Next, 2.0 parts of ammonium persulfate was added, and a mixture of the vinyl monomer and water having the following composition was continuously added over 2 hours with stirring, and then aged for 2 hours at the same temperature. The pH was adjusted to 9.0 to complete the polymerization. An aqueous liquid of resin (a) having a solid content of 20.0% was obtained.
(Mixture of vinyl monomer and water)
Acrylamide 30.0 parts Methacrylamide 35.0 parts Methacrylic acid 10.0 parts 2-Hydroxyethyl methacrylate 20.0 parts Methyl acrylate 5.0 parts Distilled water 210.0 parts

Example 1
<Production of water dispersion containing water-soluble resin (a) and organic particles (b)>
A separable flask equipped with a stirrer and reflux cooling was charged with 360 parts by weight of distilled water, replaced with nitrogen gas, and then heated to 80 ° C. Next, 2.0 parts of ammonium persulfate was added, and then a vinyl monomer emulsion having the following composition was continuously added over 3 hours, and further maintained for 3 hours, and adjusted to pH 9.0 with aqueous ammonia. The polymerization was completed. A dispersion composed of organic particles (b) having a solid content of 20.0% was obtained. An aqueous dispersion was prepared by mixing the water-soluble resin (a) obtained in Production Example 1 at a ratio of (a) :( b) = 1: 9.
(Vinyl monomer emulsion)
n-Butyl acrylate 95.0 parts Methacrylic acid 5.0 parts Ammonium lauryl sulfate 0.1 part Distilled water 40.0 parts

Example 2
<Aqueous dispersion containing resin obtained by emulsion polymerization in the presence of water-soluble resin (a)>
A separable flask equipped with a stirrer and reflux cooling was charged with 200 parts by weight of distilled water, replaced with nitrogen gas, and then heated to 80 ° C. Next, 2.0 parts of ammonium persulfate was added, and a mixture of the vinyl monomer and water having the following composition was continuously added over 2 hours with stirring, and then aged for 2 hours at the same temperature. The pH was adjusted to 9.0 to complete the polymerization. An aqueous liquid of resin (a) having a solid content of 20.0% was obtained.
(Mixture of vinyl monomer and water)
Methacrylamide 65.0 parts Methacrylic acid 10.0 parts 2-Hydroxyethyl methacrylate 20.0 parts Methyl acrylate 5.0 parts Distilled water 210.0 parts

360.4 parts of distilled water for solid content adjustment was added to 1172 parts of the obtained aqueous liquid of resin (a), and the temperature was raised to 75 ° C. while purging with nitrogen again. Next, 1.0 part of ammonium persulfate was added, and then a vinyl monomer emulsion having the following composition was continuously added over 3 hours, and further maintained for 3 hours, and adjusted to pH 9.0 with aqueous ammonia. The polymerization was completed. An aqueous dispersion having a solid content of 20.0 was obtained.
(Vinyl monomer emulsion)
2-ethylhexyl acrylate 40.0 parts acrylic acid 5.0 parts ammonium lauryl sulfate 0.1 part distilled water 40.0 parts

Example 3
<Water dispersion obtained by polymerizing water-soluble resin (a) in the presence of organic particles (b) obtained by polymerizing one or more vinyl monomers>
A separable flask equipped with a stirrer and reflux cooling was charged with 370.4 parts by weight of distilled water, replaced with nitrogen gas, and then heated to 80 ° C. Next, 2.0 parts of ammonium persulfate was added, and then a vinyl monomer emulsion having the following composition was continuously added over 3 hours, and further maintained for 3 hours, and adjusted to pH 9.0 with aqueous ammonia. The polymerization was completed. A dispersion composed of organic particles (b) having a solid content of 20.0% was obtained.
n-Butyl acrylate 45.0 parts Acrylonitrile 35.0 parts Methyl methacrylate 8.0 parts Acrylic acid 5.0 parts N-methylolacrylamide 2.0 parts Ammonium lauryl sulfate 0.1 part Distilled water 40.0 parts

Distilled water (200 parts by weight) was charged in 510 parts of the aqueous resin (b) solution, which was replaced with nitrogen gas, and then heated to 80 ° C. Next, 2.0 parts of ammonium persulfate was added, and a mixture of the vinyl monomer and water having the following composition was continuously added over 2 hours with stirring, and then aged for 2 hours at the same temperature. The pH was adjusted to 9.0 to complete the polymerization. An aqueous liquid of resin (a) having a solid content of 20.0% was obtained.
(Mixture of vinyl monomer and water)
Methacrylamide 65.0 parts Methacrylic acid 10.0 parts 2-Hydroxyethyl methacrylate 20.0 parts Methyl acrylate 5.0 parts Distilled water 210.0 parts

Example 4
<Production of water dispersion containing water-soluble resin (a) and organic particles (b)>
A separable flask equipped with a stirrer and reflux cooling was charged with 360 parts by weight of distilled water, replaced with nitrogen gas, and then heated to 80 ° C. Next, 2.0 parts of ammonium persulfate was added, and then a vinyl monomer emulsion having the following composition was continuously added over 3 hours, and further maintained for 3 hours, and adjusted to pH 9.0 with aqueous ammonia. The polymerization was completed. A dispersion composed of organic particles (b) having a solid content of 20.0% was obtained. An aqueous dispersion was prepared by mixing the water-soluble resin (a) obtained in Production Example 2 with a ratio of (a) :( b) = 1: 9.
(Vinyl monomer emulsion)
n-Butyl acrylate 95.0 parts Methacrylic acid 5.0 parts Ammonium lauryl sulfate 0.1 part Distilled water 40.0 parts

Comparative Example 1
Instead of the acrylic water dispersion, styrene butadiene latex (volume average particle size: 160 nm, solid content concentration: 48% by weight) was used as it was.

<Swellability of resin to electrolyte>
The emulsion of Examples 1 to 4 or Comparative Example 1 was applied to a glass plate and dried at 120 ° C. for 3 hours to obtain a film. The film was immersed in an ethylene carbonate (EC) / methyl ethyl carbonate (MEC) = 1/1 (vol / vol) solution at 80 ° C. for 3 days, and the weight of the swollen film was measured. The weight ratio of the swollen film / the weight before swelling was calculated. Similarly, the weight ratio when the immersion solution was a potassium hydroxide (KOH) aqueous solution (20 ° C.) was calculated. The results are shown in Table 1.

<Creation of paste coating foil for electrochemical cell containing active material B or conductive additive C>
49 parts by weight of the emulsion of Examples 1 to 4 or Comparative Example 1 in 50 parts by weight of the active material B or conductive auxiliary agent C, 1 part by weight of carboxymethyl cellulose as a thickener, distilled water and, if necessary, an organic solvent are added to form a solid An electrochemical cell paste (aqueous paste) having a partial concentration of 50% by weight was prepared. Next, this electrochemical cell paste was applied to a 20 μm-thick aluminum foil or a 18 μm-thick strip-shaped copper foil, coated, dried and compression-pressed so that the film thickness after drying was 20 μm.

<Adhesion Evaluation and Appearance Evaluation of Electrochemical Cell Paste Containing Active Material B or Conductive Aid C>
The coating foil produced above was cut and affixed to a glass preparation with an instantaneous adhesive, and the coating foil was fixed to obtain a sample for evaluation. The sample for evaluation was cut at the interface between the composite layer and the current collector at a horizontal speed of 2 μm / sec with a coating film peel strength measuring device Cycus DN20 (Daiplau Intes Co., Ltd.). The peel strength at the interface between the composite material layer and the current collector was measured from the direction force. The average value of the peel strength for 3 times was taken to evaluate the adhesion. In addition, a composite material layer refers to the coating part which apply | coated and pressed the aqueous paste on aluminum foil or copper foil (current collector).
Foil appearance evaluation ○: Uniform coating surface Δ: Shading coating surface ×: Cracking coating surface The results are shown in Table 2.

<Preparation of negative electrode plate for lithium secondary battery>
Examples 1 to 4 or 3 parts by weight of the emulsion of Comparative Example 1 were mixed with 90 parts by weight of natural graphite (active material B) (LF18A manufactured by Chuetsu Graphite Industries Co., Ltd.), acetylene black (conductive aid C) (Denka Black: 7 parts by weight) was added. Next, 1 part by weight of a thickener, distilled water and, if necessary, a surfactant and an organic solvent are added to 2 parts by weight of the obtained emulsion of Example or Comparative Example, and a negative electrode having a solid content concentration of 50% by weight. A mixture slurry (aqueous paste) was prepared. Next, this negative electrode mixture slurry was applied to a negative electrode current collector made of a strip-shaped copper foil having a thickness of 18 μm, dried, and compression molded to prepare a negative electrode having a thickness of 70 μm. Each is shown in Table 3.

<Preparation of lithium secondary battery positive electrode plate>
In 3 parts by weight of the emulsion of Examples 1 to 4 or Comparative Example 1, 85.5 parts by weight of LiCoO ₂ (B) (HLC-22 manufactured by Honjo FMC Energy Systems Co., Ltd.), 8 parts by weight of artificial graphite (conducting aid C) Part, 3 parts by weight of acetylene black (conductive aid C) (Denka Black) was added. Next, a surfactant, an organic solvent, and distilled water are added as necessary and the aqueous dispersion of the obtained Examples or Formulation Comparative Examples, and a LiCoO ₂ mixture slurry (aqueous paste) having a solid content concentration of 50% by weight is added. Prepared. In addition, the obtained mixed-material slurry was made into the slurry 1A-3A and the slurry 1a, respectively. This LiCoO ₂ composite slurry was applied to an aluminum foil having a thickness of 20 μm, dried, and compression molded to produce a positive electrode having a thickness of 70 μm. Each is shown in Table 4.

<Evaluation of adhesion of lithium secondary battery>
The electrode prepared above was cut and attached to a glass preparation with an instantaneous adhesive to fix the electrode, thereby preparing a sample for evaluation. The sample for evaluation was cut at the interface between the composite layer and the current collector at a horizontal speed of 2 μm / sec with a coating film peel strength measuring device Cycus DN20 (Daiplau Intes Co., Ltd.). The peel strength at the interface between the composite material layer and the current collector was measured from the direction force.

  The average value of the peel strength for 3 times was taken to evaluate the adhesion. In addition, a compound material layer refers to the coating part which apply | coated the aqueous paste to aluminum foil or copper foil (current collector), and dried and pressed. The results are shown in Table 5.

<Preparation of non-aqueous electrolyte for lithium ion secondary battery>
As a non-aqueous solvent, a mixture of ethylene carbonate (EC) and methyl ethyl carbonate (MEC) in a ratio of EC: MEC = 4: 6 (weight ratio) was used, and then LiPF ₆ as an electrolyte was dissolved. A non-aqueous electrolyte was prepared so that the electrolyte concentration was 1.0 mol / liter.

<Production of coin-type lithium ion secondary battery>
As a negative electrode for a coin-type battery, the negative electrode was punched into a disk shape having a diameter of 14 mm to obtain a coin-shaped negative electrode having a weight of 20 mg / 14 mmφ. As a positive electrode for a coin-type battery, the positive electrode was punched into a disk shape having a diameter of 13.5 mm to obtain a coin-shaped positive electrode having a weight of 42 mg / 13.5 mmφ.

  Using the coin-shaped negative electrode, the positive electrode, and a separator made of a microporous polypropylene film having a thickness of 25 μm and a diameter of 16 mm, the negative electrode, the separator, and the positive electrode are placed in the negative electrode can of a stainless steel 2032 size battery can. Laminated. Thereafter, 0.04 ml of the non-aqueous electrolyte was injected into the separator, and then an aluminum plate (thickness 1.2 mm, diameter 16 mm) and a spring were stacked on the laminate.

  Finally, by covering the positive electrode can of the battery via a polypropylene gasket and caulking the can lid, the airtightness inside the battery was maintained, and a coin-type battery having a diameter of 20 mm and a height of 3.2 mm was produced. .

<Evaluation of electrode swellability>
Using the coin-type battery, this battery is connected to Nagano Co., Ltd. under the condition of a constant current of 0.5 mA and a constant voltage of 4.2 V until the current value at a constant voltage of 4.2 V reaches 0.05 mA. The battery was charged, and then discharged under the conditions of a constant current of 1 mA and a constant voltage of 3.0 V until the current value at a constant voltage of 3.0 V was 0.05 mA. This cycle was repeated 100 times, and the thickness (L1) of the electrode mixture layer after 100 cycles was compared with the thickness (L2) of the electrode mixture layer before electrolyte injection.
The results are shown in Table 6. The result is indicated by (L1 / L2).

<Evaluation of battery cycle characteristics>
The cycle was repeated 500 times by the same evaluation method as the electrode swelling property, and the capacity (%) after 500 cycles with respect to the initial battery capacity was evaluated.
Table 7 shows the evaluation results.

<Production of electric double layer capacitor electrode>
Conducted on 100 parts by weight of activated carbon (B) (Kuraray Co., Ltd. RP-20), 3 parts by weight of acetylene black (C) (Denka Black), 2 parts by weight of Ketjen Black (C) (Ketjen Black International Co., Ltd. EC600JD) 5 parts by weight of the emulsions prepared in Examples 1 to 4 and Comparative Example 1 are mixed in terms of solid content, and a surfactant, an organic solvent and distilled water are added as necessary, and a composite material having a solid content concentration of 50% by weight. A slurry (aqueous paste) was prepared.

  Next, these mixed material slurries were applied to a current collector made of a strip-shaped aluminum foil having a thickness of 20 μm, dried, and compression molded to prepare electrodes having a thickness of 70 μm (Formation Examples 1C to 3C and Formulation Comparative Example 1c).

<Evaluation of adhesion of electric double layer capacitor>
Using the electrode prepared above, the peel strength of the electrode was measured by the same method as the evaluation performed with the lithium secondary battery, and the adhesion was evaluated.
The results are shown in Table 8.

<Preparation of electrolyte for electric double layer capacitor>
Tetraethylammonium tetrafluoroborate was dissolved in propylene carbonate to prepare an electrolytic solution so that the electrolyte concentration was 1.5 mol / liter.

<Production of coin-type electric double layer capacitor>
The electrode was punched into a disk shape having a diameter of 14 mm to obtain a coin-shaped electrode having a weight of 20 mg / 14 mmφ. Using the above-mentioned coin-shaped electrode and a separator made of a microporous polypropylene film having a thickness of 25 μm and a diameter of 16 mm, the electrode, the separator and the electrode were laminated in this order in the negative electrode can of a stainless steel 2032 size battery can. . Thereafter, 0.04 ml of the electrolytic solution was injected into the separator, and then an aluminum plate (thickness 1.2 mm, diameter 16 mm) and a spring were stacked on the laminate.

  Finally, the battery can is covered with a polypropylene gasket and the can lid is caulked to maintain the airtightness of the battery, and a coin-type electric double layer capacitor having a diameter of 20 mm and a height of 3.2 mm is obtained. Produced.

<Characteristic evaluation of electric double layer capacitor>
Using the produced coin-type electric double layer capacitor, the battery was charged at a constant current of 10 mA to 2.7 V for 10 minutes, and then discharged at a constant current of 1 mA. The capacitance was determined from the obtained charge / discharge characteristics.

  The internal resistance was calculated from charge / discharge characteristics according to the calculation method of standard RC-2377 established by the Japan Electronics and Information Technology Industries Association. Table 9 shows the evaluation results of the capacitor using each electrode.

<Preparation of nickel metal hydride battery positive electrode>
Further, 95 parts by weight of nickel hydroxide powder (B), 5 parts by weight of acetylene black (C) (Denka Black), and 1.0 part by weight in terms of solid content of carboxymethyl cellulose (CMC1160) prepared to 1.2% by weight The emulsion prepared in Examples 1 to 4 or Comparative Example 1 was mixed with 2.0 parts by weight in terms of solid content and distilled water to prepare a mixture paste (aqueous paste) having a solid content concentration of 55% by weight.

  This composite paste was applied to a nickel-plated steel plate having a thickness of 30 μm, dried, and then pressure-molded to prepare sheet-like positive plates (Formation Examples 1D to 3D and Formulation Comparative Example 1d).

<Preparation of negative electrode for nickel metal hydride battery>
95 parts by weight of a hydrogen storage alloy (B) made of Ni, Co, Mn and Al containing misch metal and having an average particle diameter of 30 μm, 5 parts by weight of acetylene black (C) (Denka black), Examples 1 to 4 or Comparative Examples 1 emulsion was mixed with 2.5 parts by weight in terms of solid content and distilled water to obtain a composite paste having a solid content concentration of 50% by weight.
This composite paste was applied to a punching metal having a thickness of 30 μm, dried, and pressure-molded to prepare sheet-like negative electrode plates (Formation Examples 1E to 3E and Formulation Comparative Example 1e).

<Evaluation of adhesion of nickel metal hydride batteries>
The peel strength of the electrode plate produced above was measured by the same method as the evaluation performed with the lithium secondary battery, and the adhesion was evaluated.
The results are shown in Table 10.

<Production of nickel metal hydride batteries>
The negative electrode plate or the positive electrode plate was punched into a disk shape having a diameter of 14 mm to obtain a coin-shaped electrode having a weight of 20 mg / 14 mmφ.

  Using a separator made of a coin-shaped electrode and a microporous polypropylene film having a thickness of 25 μm and a diameter of 16 mm, a negative electrode can of a stainless steel 2032 size battery can is laminated in the order of a negative electrode, a separator and a positive electrode. After injecting an aqueous potassium oxide solution (specific gravity at 20 ° C. of 1.3), an aluminum plate (thickness 1.2 mm, diameter 16 mm) and a spring were stacked on the laminate.

  Finally, by covering the positive electrode can of the battery via a polypropylene gasket and caulking the can lid, the airtightness inside the battery was maintained, and a coin-type battery having a diameter of 20 mm and a height of 3.2 mm was produced. .

<Evaluation of battery cycle characteristics>
Using the coin battery prepared above, this battery was charged with 0.2 ItA until −Δ10 mV, and then discharged with 0.2 ItA until the voltage became 1 V. This cycle was repeated 500 times, and the capacity (%) after 500 cycles with respect to the initial battery capacity was evaluated.
The evaluation results are shown in Table 11.

  As described above, the battery obtained using the electrochemical cell paste of the present invention is a battery that is electrochemically stable, has good adhesion, has little battery swelling, and has a particularly high cycle life due to charge and discharge. Can be obtained.

Comparative Example 2
A separable flask equipped with a stirrer and reflux cooling was charged with 295 parts by weight of distilled water and 4.0 parts of sodium dodecylbenzenesulfonate, and the temperature was raised to 80 ° C. after replacement with nitrogen gas. Next, after adding 3.0 parts of azobisisobutyronitrile, a vinyl monomer emulsion A having the following composition was continuously added over 3 hours, and further maintained for 3 hours to complete the polymerization. Further, a vinyl monomer emulsion B having the following composition was continuously dropped over 2 hours, and was further maintained for 2 hours to complete the polymerization. Next, after cooling to 40 ° C. or lower, the pH was adjusted to 9.0 with aqueous ammonia to obtain a dispersion composed of organic particles having a solid content of 32.5%.
(Vinyl monomer emulsion A)
n-butyl acrylate 68.0 parts Styrene 20.0 parts Acrylonitrile 4.0 parts Methyl methacrylate 4.0 parts Itaconic acid 4.0 parts Divinylbenzene 1.0 part Sodium dodecylbenzenesulfonate 1.0 part Distilled water 40.0 Part (Vinyl monomer emulsion B)
Methyl methacrylate 40.0 parts Styrene 30.0 parts Divinylbenzene 1.0 part Sodium dodecylbenzenesulfonate 0.7 parts Distilled water 40.0 parts

<Preparation of lithium secondary battery positive electrode plate>
To 2 parts by weight of the emulsion (aqueous dispersion) obtained in Example 3 or Comparative Example 2, 94 parts by weight of LiFePO ₄ (Formosa Energy & Material Technology Co., Ltd. STCM30050) as active material B, and acetylene black as conductive auxiliary agent C (Denka Black) 3 parts by weight, 1 part by weight of a thickener carboxymethylcellulose and distilled water were added to prepare a LiFePO ₄ mixture slurry (aqueous paste) having a solid content concentration of 63% by weight. In addition, the obtained mixed-material slurry was made into the slurry F and the slurry G, respectively.

This LiFePO ₄ composite slurry was applied to an aluminum foil having a thickness of 20 μm, dried, and compression molded to prepare positive electrodes having a composite slurry thickness of 110 μm and 70 μm.
The appearance of the aluminum foil at this time was evaluated according to the following. The results are shown in Table 12.

<Foil appearance evaluation>
○: Uniform coating film surface Δ: Shading coating film surface ×: Cracking coating film surface

<Creation of paste coating foil for electrochemical cell containing conductive aid>
As a conductive additive, 50 parts by weight of the emulsion of Example 3 or Comparative Example 2 and 50 parts by weight of distilled water were added to 50 parts by weight of acetylene black to prepare an electrochemical cell paste (aqueous pastes F and G) having a solid content concentration of 25% by weight. did. Next, this electrochemical cell paste was applied to a 30 μm thick aluminum foil, dried, and compression-pressed so that the film thickness after drying was 30 μm and 10 μm.

<Adhesion evaluation and appearance evaluation of paste for electrochemical cell containing only active material and conductive aid or conductive aid>
Each of the coating foils prepared above was cut and pasted on a glass preparation with an instantaneous adhesive to fix the coating foil to obtain a sample for evaluation. The sample for evaluation was cut at the interface between the composite layer and the current collector at a horizontal speed of 2 μm / sec with a coating film peel strength measuring device Cycus DN20 (Daiplau Intes Co., Ltd.). The peel strength at the interface between the composite material layer and the current collector was measured from the direction force. The average value of the peel strength for 3 times was taken to evaluate the adhesion. In addition, a composite material layer refers to the coating part which apply | coated and pressed the aqueous paste on the aluminum foil (current collector). Moreover, the external appearance of the aluminum foil was evaluated by the same method as described above.
The results are shown in Table 12.

  From this result, the present invention can make the coating film thicker than the substrate. Thereby, the electrostatic capacitance of an electrochemical cell can be enlarged.

Claims (12)

  Water-soluble resin (a) obtained by polymerizing a monomer group containing at least a polymerizable monomer of unsaturated carboxylic acids and (meth) acrylamide, and organic particles (b) (however, water-soluble resin) An acrylic aqueous dispersion for electrochemical cells, comprising (except for (a)).   2. The acrylic aqueous dispersion for an electrochemical cell according to claim 1, wherein the polymerizable monomer of unsaturated carboxylic acid contains substantially no dicarboxylic acid and monocarboxylic acid.   The acrylic water dispersion for an electrochemical cell according to claim 2, wherein the polymerizable monomer of the unsaturated carboxylic acid does not substantially contain a conjugated diene monomer.   The acrylic aqueous dispersion for an electrochemical cell according to any one of claims 1 to 3, wherein the pH is in the range of 7 to 11.   The weight ratio of the water-soluble resin (a) to the organic particles (b) is (a) 10 to 90% by weight and (b) 90 to 10% by weight (however, the sum of (a) and (b) is 100). The acrylic aqueous dispersion for an electrochemical cell according to any one of claims 1 to 4, wherein the acrylic aqueous dispersion is for electrochemical cells.   Furthermore, at least 1 sort (s) chosen from surfactant (x) and a viscosity modifier (y) is included, The acrylic water dispersion for electrochemical cells as described in any one of Claims 1-5 characterized by the above-mentioned. .   The organic particles (b) are particles obtained by polymerizing one or more kinds of vinyl monomers in the presence of the water-soluble resin (a). Acrylic water dispersion for electrochemical cell.   The water-soluble resin (a) is a resin obtained by polymerization in the presence of organic particles (b) obtained by polymerizing one or more vinyl monomers. The acrylic water dispersion for electrochemical cells according to claim 1.   An electricity containing an acrylic aqueous dispersion for an electrochemical cell according to any one of claims 1 to 8, and at least one selected from an active material (B) and a conductive additive (C). Aqueous paste for chemical cells.   The aqueous paste for electrochemical cells according to claim 9, comprising 0 to 40 parts by weight of an organic solvent with respect to 100 parts by weight of water contained in the acrylic aqueous dispersion for electrochemical cells.   The electrode plate for electrochemical cells obtained using the aqueous paste for electrochemical cells according to claim 9 or 10.   A secondary battery obtained using the electrode plate for an electrochemical cell according to claim 11.