JP6003517B2 - Binder resin composition for non-aqueous secondary battery electrode - Google Patents

Description

  The present invention relates to a binder resin composition for a non-aqueous secondary battery electrode excellent in electrolytic solution resistance, binding property, and flexibility. Furthermore, it is related with the binder resin composition for non-aqueous secondary battery electrodes which can be used conveniently for the non-aqueous secondary battery excellent in charging / discharging cycling characteristics and high capacity | capacitance, and a lithium ion secondary battery.

  In recent years, due to advances in electronic technology, the performance of electronic devices has improved, and miniaturization and portability have progressed, and the demand for secondary batteries with high energy density as the power source has increased. Secondary batteries include, for example, nickel metal hydride secondary batteries, lithium ion secondary batteries, etc. These secondary batteries are also being developed for high-capacity and long-life products due to the miniaturization and weight reduction of equipment. .

  The electrode of the secondary battery is composed of an electrode active material, a conductive additive, and a binder that binds these to a current collector. In the secondary battery, since the positive electrode or the negative electrode repeats volume expansion and contraction during charge and discharge, the active material and the conductive agent may be dropped, thereby shortening the charge / discharge cycle life. For this reason, the electrode binder is required to have toughness and adhesion that can withstand the swelling and shrinkage of the electrode. In addition, since the inside of the battery is filled with the electrolytic solution, if the binder easily swells in the electrolytic solution, the adhesiveness is lowered, or the conductive path between the active material and the conductive agent is cut, so that the battery performance is deteriorated. There was a problem that led to.

  With respect to these problems, Patent Document 1 states that a binder containing a monomer unit having a nitrile group and a hydroxyl group or a carboxyl group has a low degree of swelling with respect to the electrolytic solution and a good binding property. However, a binder having a nitrile group tends to be rigid and has a problem of insufficient flexibility. Patent Document 2 discloses a non-containing fluorine-containing segment formed from a mixture of a fluorine-containing monomer alone or a fluorine-containing monomer and an alkyl (meth) acrylate having an alkyl group having 12 to 22 carbon atoms. A block copolymer with fluorine has a good balance between adhesion and low swelling to the electrolyte. However, polymers containing fluorine still have problems in terms of adhesion due to their crystallinity and low polarity derived from fluorine.

Japanese Patent No. 4311002 JP2002-141068

  The present invention is a non-aqueous secondary that has a low degree of swelling with respect to the electrolyte, excellent flexibility and adhesion to the current collector, and retains a high discharge capacity even under high temperature environments due to repeated charge and discharge and heat generation. It aims at providing the binder resin composition for non-aqueous secondary battery electrodes which can manufacture a battery, a non-aqueous secondary battery electrode, and the non-aqueous secondary battery using this electrode.

That is, the present invention is a method for producing a binder resin composition for a non-aqueous secondary battery electrode that polymerizes a monomer mixture in an aqueous medium containing a surfactant, a polymerization initiator, and water as essential components,
The monomer mixture contains a radically polymerizable ethylenically unsaturated monomer (A) having a branched alkyl group having 10 to 40 carbon atoms,
The present invention relates to a method for producing a binder resin composition for a non-aqueous secondary battery electrode, wherein the monomer mixture is emulsified in the presence of a surfactant and water and then the average particle size is emulsified to 2 μm or less .

In the present invention, the monomer mixture contains an ethylenically unsaturated monomer (B) other than the ethylenically unsaturated monomer (A), and the ethylenically unsaturated monomer (B) An alkoxysilyl group-containing monofunctional ethylenically unsaturated monomer (a), an N-methylol group-containing monofunctional ethylenically unsaturated monomer (b), and two or more ethylenically unsaturated groups in one molecule The monomer (d) having at least one selected from the group consisting of the monomer (c) and a monomer having one ethylenically unsaturated group and a cyclic structure in one molecule. The present invention relates to a method for producing a binder resin composition for a non-aqueous secondary battery electrode.
The present invention also relates to a method for producing the binder resin composition for nonaqueous secondary battery electrodes, wherein the ethylenically unsaturated monomer (A) is contained in the monomer mixture in an amount of 5% by weight or more. .

Further, in the present invention, the ethylenically unsaturated monomer (B) contains 10 monomers (d) having one ethylenically unsaturated group and a cyclic structure in one molecule in the monomer mixture. It is related with the manufacturing method of the said binder resin composition for non-aqueous secondary battery electrodes characterized by containing -60weight%.

Further, the present invention, the nonaqueous secondary battery electrode, characterized in that there use the resulting nonaqueous secondary battery electrode binder resin composition by the method for producing a nonaqueous secondary battery electrode binder resin composition It relates to the manufacturing method .

Furthermore, the present invention relates to a method for producing a nonaqueous secondary battery, characterized in that there use a non-aqueous secondary cell electrode obtained by the manufacturing method.

  If the binder resin composition for non-aqueous secondary battery electrodes of the present invention is used, it has excellent electrolytic solution resistance, high flexibility, high adhesion to the current collector, repeated charging / discharging, and high temperature environment due to heat generation. Even if it is below, it is possible to provide a long-life nonaqueous secondary battery capable of reducing a decrease in discharge capacity in a charge / discharge cycle.

<Binder composition for non-aqueous secondary battery electrode>
The binder composition for a non-aqueous secondary battery electrode according to the present invention is a monomer mixture containing a radically polymerizable ethylenically unsaturated monomer (A) having a branched alkyl group having 10 to 40 carbon atoms as an essential component. It is characterized by being polymerized.

<About monomer (A)>
The monomer (A) in the present invention is a radically polymerizable ethylenically unsaturated monomer having a branched alkyl group having 10 to 40 carbon atoms, and is hydrophilic by having a hydrophobic long-chain alkyl. Since it is difficult to swell with respect to the electrolytic solution and has a branched structure, the crystallinity is lowered as compared with the linear structure, and the wettability to the adherend is improved, so that the adhesion is not lowered. Further, by having a branched structure, flexibility is increased as compared with a straight chain structure, and it is possible to prevent the created electrode film from being cracked or peeled off from the current collector during deformation such as a winding process.

The monomer (A) is preferably contained in the monomer mixture in an amount of 5% by weight or more. More preferably, it is 10 weight%-80 weight%, More preferably, it is 20 weight%-60 weight%. If it is less than 5% by weight, the low swellability to the electrolyte may be insufficient.

In consideration of the balance between adhesion and difficulty of swelling into the electrolyte, the carbon number is preferably 10 to 30, more preferably 14 to 24. When the number of carbon atoms is less than 10, the electrolyte solution lacks low swellability, and when it is more than 40, the adhesiveness decreases.

As the monomer (A), for example,
(Meth) acrylic acid branched decyl, (meth) acrylic acid branched undecyl, (meth) acrylic acid branched lauryl, (meth) acrylic acid branched tridecyl, (meth) acrylic acid branched myristyl, (meth) acrylic acid branched pentadecyl, (meta ) Branched cetyl acrylate, (meth) acrylic acid branched heptadecyl, (meth) acrylic acid branched stearyl, (meth) acrylic acid branched oleyl and the like. Among these monomers, (meth) acrylic acid branched cetyl and (meth) acrylic acid branched stearyl are preferable. These monomers having a branched alkyl group can be used alone or in combination.

<About monomer (B)>
As the ethylenically unsaturated monomer (B) other than the monomer (A),
An alkoxysilyl group-containing monofunctional ethylenically unsaturated monomer (a), an N-methylol group-containing monofunctional ethylenically unsaturated monomer (b), and two or more ethylenically unsaturated groups in one molecule It is preferable to use at least one monomer selected from the group consisting of the monomer (c) it has. Monomers (a) to (c) are self-crosslinking reactive functional groups, and the resistance to electrolytic solution can be improved by introducing a crosslinked structure into the polymer. Monomers (a) to (c) are preferably used in an amount of 0.1 to 5% by weight in a total of 100% by weight of the whole ethylenically unsaturated monomer. More preferably, it is 0.25 to 3% by weight. If the monomers (a) to (c) are less than 0.1% by weight, crosslinking may be insufficient and the resistance to electrolyte solution may deteriorate. On the other hand, if it exceeds 5% by weight, a problem may occur in the polymerization stability, or even if it can be polymerized, a problem may occur in the storage stability.

  Examples of the alkoxysilyl group-containing monofunctional ethylenically unsaturated monomer (a) include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltributoxysilane, γ- Methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-methacryloxymethyltri Examples include methoxysilane, γ-acryloxymethyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxysilane, and vinylmethyldimethoxysilane.

  Examples of the N-methylol group-containing monofunctional ethylenically unsaturated monomer (b) include N-methylol (meth) acrylamide, N, N-di (methylol) acrylamide, N-methylol-N-methoxymethyl (meta). ) Alkyrol (meth) acrylamides such as acrylamide.

  Examples of the monomer (c) having two or more ethylenically unsaturated groups in one molecule include allyl (meth) acrylate, 1-methylallyl (meth) acrylate, and 2-methylallyl (meth) acrylate. 1-butenyl (meth) acrylate, 2-butenyl (meth) acrylate, 3-butenyl (meth) acrylate, 1,3-methyl-3-butenyl (meth) acrylate, 2- (meth) acrylate 2- Chloroallyl, 3-chloroallyl (meth) acrylate, o-allylphenyl (meth) acrylate, 2- (allyloxy) ethyl (meth) acrylate, allyl lactyl (meth) acrylate, citronellyl (meth) acrylate, (meth) Geranyl acrylate, rosinyl (meth) acrylate, cinnamyl (meth) acrylate, diallyl maleate, diallyl itaconic acid, (Meth) acrylic acid esters containing ethylenically unsaturated groups such as (meth) vinyl acrylate, vinyl crotonate, vinyl oleate, vinyl linolenate, 2- (2′-vinyloxyethoxy) ethyl (meth) acrylate; Di (meth) acrylic acid ethylene glycol, di (meth) acrylic acid triethylene glycol, di (meth) acrylic acid tetraethylene glycol, tri (meth) acrylic acid trimethylolpropane, tri (meth) acrylic acid pentaerythritol, diacrylic acid Polyfunctional (meth) acrylic acid esters such as 1,1,1-trishydroxymethylethane, 1,1,1-trishydroxymethylethane triacrylate, 1,1,1-trishydroxymethylpropanetriacrylic acid; Divinyl benzene, divinyl adipate, etc. Cycloalkenyl like; diallyl isophthalate, diallyl phthalate, etc. diallyl such as diallyl maleate and the like.

  Further, as the ethylenically unsaturated monomer (B) other than the monomer (A), a monomer (d) having one ethylenically unsaturated group and a cyclic structure in one molecule may be used. It is preferable to contain 10 to 60% by weight in the monomer mixture. More preferably, it is 10 to 40% by weight. By using the monomer (d), adhesion with the active material and the conductive auxiliary agent is improved. If it is less than 10% by weight, sufficient adhesion may not be obtained. If it exceeds 60% by weight, flexibility may be adversely affected.

Examples of the monomer (d) having one ethylenically unsaturated group and a cyclic structure in one molecule include alicyclic ethylenically unsaturated monomers and aromatic ethylenically unsaturated monomers. . Examples of the alicyclic ethylenically unsaturated monomer include cyclohexyl (meth) acrylate and isobornyl (meth) acrylate, and examples of the aromatic ethylenically unsaturated monomer include benzyl (meth) acrylate. Phenoxyethyl (meth) acrylate, styrene, α-methylstyrene, 2-methylstyrene, chlorostyrene, allylbenzene, ethynylbenzene and the like.

  As the monomer having an ethylenically unsaturated group other than the above-described monomer (A), monomer (a), (b), (c), (d),

Maleic acid, fumaric acid, itaconic acid, citraconic acid, or alkyl or alkenyl monoesters thereof, phthalic acid β- (meth) acryloxyethyl monoester, isophthalic acid β- (meth) acryloxyethyl monoester, terephthalic acid Carboxyl group-containing ethylenically unsaturated monomers such as β- (meth) acryloxyethyl monoester, succinic acid β- (meth) acryloxyethyl monoester, acrylic acid, methacrylic acid, crotonic acid and cinnamic acid.

Sulfonic acid groups such as vinyl sulfonic acid, styrene sulfonic acid, tertiary butyl acrylamide sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, (meth) acrylic acid butyl-4-sulfonic acid, (meth) acrylooxybenzene sulfonic acid Contains ethylenically unsaturated monomers.

Diphenyl (2-acryloyloxyethyl) phosphate, diphenyl (2-methacryloyloxyethyl) phosphate, phenyl (2-acryloyloxyethyl) phosphate, acid phosphooxyethyl (meth) acrylate, acid phosphooxypropyl (meth) acrylate, (Meth) acryloyl oxyethyl acid phosphate monoethanolamine salt, 3-chloro-2-acid phosphooxypropyl (meth) acrylate, acid phosphooxypolyoxyethylene glycol mono (meth) acrylate, acid phosphooxypoly Phosphoric acid group-containing ethylenically unsaturated monomers such as oxypropylene glycol (meth) acrylate and allyl alcohol acid phosphate.

Primary amide group-containing ethylenically unsaturated monomers such as (meth) acrylamide.

N-methoxymethyl- (meth) acrylamide, N-ethoxymethyl- (meth) acrylamide, N-propoxymethyl- (meth) acrylamide, N-butoxymethyl- (meth) acrylamide, N-pentoxymethyl- (meth) acrylamide Monoalkoxy (meth) acrylamides such as

N, N-di (methoxymethyl) acrylamide, N-ethoxymethyl-N-methoxymethylmethacrylamide, N, N-di (ethoxymethyl) acrylamide, N-ethoxymethyl-N-propoxymethylmethacrylamide, N, N- Di (propoxymethyl) acrylamide, N-butoxymethyl-N- (propoxymethyl) methacrylamide, N, N-di (butoxymethyl) acrylamide, N-butoxymethyl-N- (methoxymethyl) methacrylamide, N, N- Dialkoxy (meth) acrylamides such as di (pentoxymethyl) acrylamide and N-methoxymethyl-N- (pentoxymethyl) methacrylamide.

Dialkylamino (meth) acrylamides such as N, N-dimethylaminopropylacrylamide and N, N-diethylaminopropylacrylamide.

Dialkyl (meth) acrylamides such as N, N-dimethylacrylamide and N, N-diethylacrylamide.

Carbonyl group-containing unsaturated monomers such as diacetone acrylamide, diacetone methacrylamide, acrolein, N-vinylformamide, vinyl methyl ketone, and vinyl ethyl ketone.

Dialkylamino group-containing ethylenically unsaturated monomers such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, methylethylaminoethyl (meth) acrylate, dimethylaminostyrene and diethylaminostyrene.

Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, hexyl (meth) Alkyl (meth) acrylates including straight and branched chains such as acrylate, octyl (meth) acrylate, and nonyl (meth) acrylate.

Decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl ( Linear alkyl (meth) acrylates such as (meth) acrylate, nonadecyl (meth) acrylate, icosyl (meth) acrylate, heicosyl (meth) acrylate and docosyl (meth) acrylate.

2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, 4-hydroxyvinylbenzene, 1-ethynyl-1-cyclohexanol, allyl Hydroxyl-containing ethylenically unsaturated monomers such as alcohol.

Glycidyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, glycidyl allyl ether, 2,3-epoxy-2-methylpropyl (meth) acrylate, 3,4-epoxycyclohexyl (meth) acrylate, 4-vinyl Epoxy group-containing unsaturated monomers such as -1-cyclohexene-1,2-epoxide, glycidyl cinnamate, 1,3-butadiene monoepoxide, and Celoxide 2000 (manufactured by Daicel Chemical Industries, Ltd.).

Perfluoromethylmethyl (meth) acrylate, perfluoroethylmethyl (meth) acrylate, 2-perfluorobutylethyl (meth) acrylate, 2-perfluorohexylethyl (meth) acrylate, 2-perfluorooctylethyl (meth) acrylate , 2-perfluoroisononylethyl (meth) acrylate, 2-perfluorononylethyl (meth) acrylate, 2-perfluorodecylethyl (meth) acrylate, perfluoropropylpropyl (meth) acrylate, perfluorooctylpropyl (meta ) Perfluoroalkyl having a C 1-20 perfluoroalkyl group such as acrylate, perfluorooctyl amyl (meth) acrylate, perfluorooctyl undecyl (meth) acrylate, etc. (Meth) acrylate.

Perfluoroalkyl group-containing ethylenically unsaturated monomers such as perfluoroalkylalkylenes such as perfluorobutylethylene, perfluorohexylethylene, perfluorooctylethylene, and perfluorodecylethylene.

Polyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, propoxypolyethylene glycol (meth) acrylate, n-butoxypolyethylene glycol (meth) acrylate, n-pentoxypolyethylene glycol (meth) Acrylate, phenoxypolyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, propoxypolypropylene glycol (meth) acrylate, n-butoxypolypropylene glycol (meth) acrylate N-Pentoxypolypropylene Recall (meth) acrylate, phenoxypolypropylene glycol (meth) acrylate, polytetramethylene glycol (meth) acrylate, methoxypolytetramethylene glycol (meth) acrylate, phenoxytetraethylene glycol (meth) acrylate, hexaethylene glycol (meth) acrylate, An ethylenically unsaturated monomer having a polyether chain such as methoxyhexaethylene glycol (meth) acrylate.

An ethylenically unsaturated monomer having a polyester chain such as a lactone-modified (meth) acrylate.

(Meth) acrylic acid dimethylaminoethyl methyl chloride salt, trimethyl-3- (1- (meth) acrylamide-1,1-dimethylpropyl) ammonium chloride, trimethyl-3- (1- (meth) acrylamidopropyl) ammonium chloride, And quaternary ammonium base-containing ethylenically unsaturated monomers such as trimethyl-3- (1- (meth) acrylamide-1,1-dimethylethyl) ammonium chloride.

Fatty acid vinyl monomers such as vinyl acetate, vinyl butyrate, vinyl propionate, vinyl hexanoate, vinyl caprylate, vinyl laurate, vinyl palmitate, and vinyl stearate.

Vinyl ether compounds such as butyl vinyl ether and ethyl vinyl ether;
Α-olefin monomers such as 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene and 1-hexadecene.

Allyl monomers such as allyl acetate, allylbenzene, and allyl cyanide.

Vinyl monomers such as vinyl cyanide, vinyl cyclohexane, vinyl methyl ketone, styrene, α-methyl styrene, 2-methyl styrene, chlorostyrene.

Examples include ethynyl monomers such as acetylene, ethynylbenzene, and ethynyltoluene.
These may use only 1 type, or can mix and use 2 or more types.

  Among the ethylenically unsaturated monomers described above, the use of a monomer containing an acidic group, such as a carboxyl group-containing ethylenically unsaturated monomer, improves adhesion to the current collector, In the case of polymerization as a solvent, neutralization is preferable because the stability of the particles can be increased.

<Method for producing binder resin composition for non-aqueous secondary battery electrode>
As a polymerization method for producing the binder resin composition for a non-aqueous secondary battery electrode of the present invention, existing methods such as solution polymerization, bulk polymerization, suspension polymerization, dispersion polymerization, and emulsion polymerization can be applied. . Among these, it is preferable to use a heterogeneous reaction such as suspension polymerization, dispersion polymerization or emulsion polymerization from the viewpoint of introducing a self-crosslinking type reactive functional group or from the viewpoint of close contact with an active material. Moreover, when using water as a solvent, surfactant can be used as needed.

When water is used as the solvent, it is preferable to polymerize the monomer mixture after emulsifying the monomer mixture to an average particle size of 2 μm or less using a surfactant. Usually, when the water solubility of a monomer is too small in emulsion polymerization, the monomer cannot be supplied from the monomer oil droplets to the polymer particles, and the polymerization reaction cannot proceed smoothly. Monomer (A) used in the present invention has very low solubility in water, and when produced by ordinary emulsion polymerization, supply of monomer (A) from monomer oil droplets to polymer particles is insufficient, Polymer particles derived from surfactant micelles having a small amount of monomer (A) and polymer particles derived from monomer oil droplets containing a large amount of monomer (A) obtained by polymerization of monomer oil droplets containing monomer (A) as they are Two types are produced, and the intended physical properties may not be obtained.

The smaller the monomer oil droplets, the more preferential polymerization is from the monomer oil droplets. Therefore, the average particle diameter of the monomer droplets is 2 μm or less, preferably 1 μm or less, more preferably 500 nm or less. When the average particle size is larger than 2 μm, aggregates increase or particles with a uniform composition cannot be formed, and thus the adhesion may be lowered when used for an electrode film.

In addition, when finely emulsifying monomer oil droplets, a small amount of poorly water-soluble substance such as hexadecane is added to suppress the coarsening of oil droplets, usually called Ostwald ripening. Since the body (A) plays the role of a poorly water-soluble substance, the fine emulsified particles can exist stably without adding hexadecane or the like.

An emulsifier is used for emulsifying the monomer. The emulsifier used in the present invention is not particularly limited, but when performing fine emulsification of monomer oil droplets, for example, an ultrasonic homogenizer, a homomixer, a milder, an attritor, a (ultra) high pressure homogenizer, a colloid mill, etc. Can be mentioned. The average particle diameter referred to here represents a volume average particle diameter and can be measured by a dynamic light scattering method. The average particle diameter can be measured by the dynamic light scattering method as follows. The resin fine particle dispersion is diluted with water 200 to 1000 times according to the solid content. About 5 ml of the diluted solution is injected into a cell of a measuring apparatus [Microtrack manufactured by Nikkiso Co., Ltd.], and the measurement is performed after inputting the solvent (water in the present invention) and the refractive index condition of the resin according to the sample. The peak of the volume particle size distribution data (histogram) obtained at this time is defined as the average particle size of the present invention.

<Surfactant>
As the surfactant used in the present invention, a conventionally known surfactant such as a reactive surfactant having an ethylenically unsaturated group or a non-reactive surfactant having no ethylenically unsaturated group may be arbitrarily used. Can do.

  Reactive surfactants having an ethylenically unsaturated group can be further broadly classified into anionic and nonionic nonionic ones. In particular, when an anionic reactive surfactant or a nonionic reactive surfactant having an ethylenically unsaturated group is used, the dispersion particle size of the copolymer becomes fine and the particle size distribution becomes narrow. When used as a binder for battery electrodes, it is possible to improve the resistance to electrolytic solution, which is preferable. This anionic reactive surfactant or nonionic reactive surfactant having an ethylenically unsaturated group may be used singly or in combination.

  As an example of the surfactant, specific examples thereof will be illustrated below, but the surfactants that can be used in the present invention are not limited to those described below.

  Examples of the anionic reactive surfactant include alkyl ethers (commercially available products include, for example, Aqualon KH-05, KH-10, KH-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and Adeka Soap SR- manufactured by ADEKA Corporation. 10N, SR-20N, LATEMUL PD-104 manufactured by Kao Corporation, etc .; sulfosuccinic acid ester system (for example, LATEMUL S-120, S-120A, S-180P, S-180A manufactured by Kao Corporation) Sanyo Chemical Co., Ltd. Eleminol JS-2 etc.); alkyl phenyl ether type or alkyl phenyl ester type (commercially available products include, for example, Aqualon H-2855A, H-3855B, H-3855C, H -3856, HS-05, HS-10, HS-20, HS-30, A Corporation ADEKA rear soap SDX-222, SDX-223, SDX-232, SDX-233, SDX-259, SE-10N, SE-20N, etc. manufactured by EKA; (meth) acrylate sulfate-based (commercially available products include, for example, , Nippon Emulsifier Co., Ltd. Antox MS-60, MS-2N, Sanyo Chemical Industries Co., Ltd., Eleminol RS-30, etc.); Phosphate ester type (for example, H- 3330PL, Adeka Soap PP-70 manufactured by ADEKA Corporation) and the like.

  Nonionic reactive surfactants include, for example, alkyl ethers (for example, commercially available products such as Adeka Soap ER-10, ER-20, ER-30, ER-40 manufactured by ADEKA Corporation, LATEMUL manufactured by Kao Corporation PD-420, PD-430, PD-450, etc.); alkylphenyl ethers or alkylphenyl esters (commercially available products include, for example, Aqualon RN-10, RN-20, RN-30 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) , RN-50, Adeka Soap NE-10, NE-20, NE-30, NE-40, etc., manufactured by ADEKA Corporation; (meth) acrylate sulfate ester (commercially available products include, for example, Nippon Emulsifier Co., Ltd. RMA-564, RMA-568, RMA-1114, etc.).

  Along with the reactive surfactant having an ethylenically unsaturated group, a non-reactive surfactant having no ethylenically unsaturated group can be used in combination as necessary. Non-reactive surfactants can be broadly classified into non-reactive anionic surfactants and non-reactive nonionic surfactants.

  Examples of non-reactive nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether and other polyoxyethylene alkyl ethers. Ethylene alkyl phenyl ethers; sorbitan higher fatty acid esters such as sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate; polyoxyethylene sorbitan higher fatty acid esters such as polyoxyethylene sorbitan monolaurate; polyoxyethylene monolaur , Polyoxyethylene higher fatty acid esters such as polyoxyethylene monostearate; oleic acid monoglyceride, stearic acid mono Glycerine higher fatty acid esters such as Riseraido; polyoxyethylene-polyoxypropylene block copolymers, and the like can be exemplified polyoxyethylene distyrenated phenyl ether.

  Examples of non-reactive anionic surfactants include higher fatty acid salts such as sodium oleate; alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; alkyl sulfate salts such as sodium lauryl sulfate; Polyoxyethylene alkyl ether sulfates such as sodium lauryl ether sulfate; Polyoxyethylene alkyl aryl ether sulfates such as sodium polyoxyethylene nonylphenyl ether sulfate; Sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, polyoxyethylene lauryl Alkylsulfosuccinic acid ester salts such as sodium sulfosuccinate and derivatives thereof; polyoxyethylene distyrenated phenyl ester And the like can be exemplified ether sulfate ester salts.

  The amount of the surfactant used in the present invention is not necessarily limited, and can be appropriately selected according to physical properties required when the binder resin particles are finally used as a binder for a secondary battery electrode. For example, the surfactant is usually preferably 0.1 to 30 parts by weight, more preferably 0.3 to 20 parts by weight, based on 100 parts by weight of the total of ethylenically unsaturated monomers More preferably, it is in the range of 0.5 to 10 parts by weight.

<Polymerization initiator>
The polymerization initiator used for obtaining the binder composition of the present invention is not particularly limited as long as it has the ability to initiate radical polymerization, and a known oil-soluble polymerization initiator or water-soluble polymerization initiator is used. be able to.

  The oil-soluble polymerization initiator is not particularly limited, and examples thereof include benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl hydroperoxide, tert-butyl peroxy (2-ethylhexanoate), and tert-butyl peroxide. Organic peroxides such as oxy-3,5,5-trimethylhexanoate, di-tert-butyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4- Examples thereof include azobis compounds such as dimethylvaleronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1′-azobiscyclohexane-1-carbonitrile. These can be used alone or in combination of two or more. These polymerization initiators are preferably used in an amount of 0.1 to 10.0 parts by weight with respect to 100 parts by weight of the ethylenically unsaturated monomer.

  As the water-soluble polymerization initiator, conventionally known ones such as ammonium persulfate, potassium persulfate, hydrogen peroxide, 2,2′-azobis (2-methylpropionamidine) dihydrochloride can be preferably used. it can. Moreover, when performing emulsion polymerization, a reducing agent can be used together with a polymerization initiator if desired. Thereby, it becomes easy to accelerate the emulsion polymerization rate or to perform the emulsion polymerization at a low temperature. Examples of such a reducing agent include reducing organic compounds such as metal salts such as ascorbic acid, ersorbic acid, tartaric acid, citric acid, glucose, and formaldehyde sulfoxylate, sodium thiosulfate, sodium sulfite, sodium bisulfite, Examples include reducing inorganic compounds such as sodium bisulfite, ferrous chloride, Rongalite, thiourea dioxide, and the like. These reducing agents are preferably used in an amount of 0.05 to 5.0 parts by weight with respect to 100 parts by weight of the total ethylenically unsaturated monomer.

<Polymerization conditions>
In addition, it can superpose | polymerize by a photochemical reaction, radiation irradiation, etc. irrespective of an above described polymerization initiator. The polymerization temperature is not less than the polymerization start temperature of each polymerization initiator. For example, in the case of a peroxide-based polymerization initiator, it may be usually about 70 ° C. The polymerization time is not particularly limited, but is usually 2 to 24 hours.
<Aqueous medium>
When using an aqueous medium for this invention, a hydrophilic organic solvent can also be used in the range which does not impair the objective of this invention.

<Other materials used for reaction>
Further, if necessary, an appropriate amount of mercaptans such as octyl mercaptan, 2-ethylhexyl thioglycolate, octyl thioglycolate, stearyl mercaptan, lauryl mercaptan, t-dodecyl mercaptan can be used as a chain transfer agent.

  The binder resin composition for non-aqueous secondary battery electrodes produced by the production method of the present invention can be used for forming a positive electrode and a negative electrode of a secondary battery. In addition, it can also be used for energy devices, that is, capacitors, solar cells and the like.

  The binder resin composition for a non-aqueous secondary battery electrode of the present invention can produce a non-aqueous secondary battery electrode by blending an electrode active material, applying it to a current collector, and drying.

  In the present invention, the binder resin composition for a non-aqueous secondary battery electrode is usually 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on 100 parts by weight of the electrode active material, as its solid content. Used. If the amount is less than 0.1 part by weight, the force for binding the electrode active material to the current collector is insufficient, and the electrode active material may fall off and the battery capacity may decrease. On the other hand, if the binder composition exceeds 20 parts by weight, the resistance in the battery may increase and the capacity of the battery may decrease.

Examples of the electrode active material include the following.
The positive electrode active material is not particularly limited, and metal oxides that can be doped or intercalated with lithium ions, metal compounds such as metal sulfides, conductive polymers, and the like can be used. Examples thereof include transition metal oxides such as Fe, Co, Ni, and Mn, composite oxides with lithium, and inorganic compounds such as transition metal sulfides. Specifically, transition metal oxide powders such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , layered structure lithium nickelate, lithium cobaltate, lithium manganate, spinel structure lithium manganate, etc. Examples thereof include composite oxide powders of lithium and transition metals, lithium iron phosphate materials that are phosphate compounds having an olivine structure, and transition metal sulfide powders such as TiS ₂ and FeS. In addition, conductive polymers such as polyaniline, polyacetylene, polypyrrole, and polythiophene can also be used. Moreover, you may mix and use said inorganic compound and organic compound.
The negative electrode active material is not particularly limited as long as it can be doped or intercalated with lithium ions. For example, metal Li, alloys thereof such as tin alloys, silicon alloys, lead alloys, Li _x Fe ₂ O ₃ , Li _x Fe ₃ O ₄ , Li _x WO ₂ , lithium titanate, lithium vanadate, silicon Metal oxides such as lithium oxide, conductive polymers such as polyacetylene and poly-p-phenylene, amorphous carbonaceous materials such as soft carbon and hard carbon, artificial graphite such as highly graphitized carbon materials, or natural Examples thereof include carbonaceous powders such as graphite, carbon black, mesophase carbon black, resin-fired carbon materials, air-growth carbon fibers, and carbon fibers.
These negative electrode active materials can be used alone or in combination.

  Examples of the conductive material used in combination with the electrode active material include nickel powder, cobalt oxide, titanium oxide, and carbon. Examples of carbon include acetylene black, furnace black, graphite, carbon fiber, and fullerenes. As for the usage-amount of an electroconductive material, 0.5-10 weight part is preferable with respect to 100 weight part of electrode active materials. If the amount is less than 0.5 part by weight, the conductivity is low, and the capacity when charging / discharging at a high rate of the secondary battery may decrease. The current collector is not particularly limited as long as it is usually used for a secondary battery electrode, and examples thereof include punching metal, expanded metal, wire mesh, foam metal, and reticulated metal fiber sintered body. .

  In order to form a non-aqueous secondary battery electrode, the binder resin composition for a non-aqueous secondary battery electrode is applied to a current collector in the form of a slurry, heated and dried. As a coating method, any coater head such as a reverse roll method, a comma bar method, a gravure method, an air knife method, etc. can be used, and as a drying method, a standing drying, a blow dryer, a hot air dryer, an infrared heater, a far-infrared heater, An infrared heater can be used.

The non-aqueous secondary battery of the present invention comprises a secondary battery electrode manufactured using the binder resin composition for a non-aqueous secondary battery electrode. When producing a non-aqueous secondary battery using the non-aqueous secondary battery electrode obtained as described above, for example, a carbonate solvent such as ethylene carbonate or propylene carbonate is used as the electrolyte, and LiPF ₆ is used as the electrolyte. It is preferable to use it as a lithium ion secondary battery using a lithium ion compound such as. Furthermore, a battery is configured using components such as a separator, a current collector, a terminal, and an insulating plate. Examples of the separator include polyethylene nonwoven fabric, polypropylene nonwoven fabric, polyamide nonwoven fabric, and those obtained by subjecting them to hydrophilic treatment.

  EXAMPLES The present invention will be described more specifically with reference to the following examples. However, the following examples do not limit the scope of rights of the present invention. In the examples, “part” represents “part by weight” and “%” represents “% by weight”.

The average particle size is measured by diluting the resin fine particle dispersion with water 200 to 1000 times according to the solid content, and about 5 ml of the diluted solution is placed in a cell of a measuring device [Microtrack UPA-150, manufactured by Nikkiso Co., Ltd.]. After the injection and the refractive index conditions of water and resin were input, measurement was performed, and the peak of volume particle size distribution data (histogram) by the dynamic light scattering method was defined as the average particle size of the present invention.
In addition, since particle diameters of 7 μm or more cannot be evaluated with UPA-150, if a value of 7 μm or more was obtained from the histogram, it was set to> 7 μm.

<Manufacture of binder resin particles>
[Synthesis Example 1]
First as a reactive ammonia neutralizing anionic surfactant in a mixture of 62 parts 2-ethylhexyl acrylate, 25.5 parts methyl methacrylate, 10 parts isodecyl acrylate, 1.5 parts acrylamide and 1.0 part acrylic acid 100 parts of deionized water, 1.5 parts of “Aqualon KH-10” manufactured by Kogyo Seiyaku Co., Ltd., and 3.0 parts of “Neugen XL-80” manufactured by Daiichi Kogyo Seiyaku Co., Ltd. as a non-reactive nonionic surfactant What was dissolved in was added and stirred to obtain a pre-emulsion with an average particle size of> 7 μm.
Separately, 100 parts of ion-exchanged water was charged into a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a refluxer, and the internal temperature was raised to 70 ° C. to sufficiently substitute nitrogen. Thereafter, 10 parts of a 5% aqueous solution of potassium persulfate was added and the reaction system was maintained at 70 ° C. for 5 minutes, and then the pre-emulsion was added dropwise over 2 hours while maintaining the internal temperature at 80 ° C., followed by stirring for 2 hours. Continued. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C., and neutralized by adding 3.0 g of 25% ammonia water to obtain binder resin particles.

[Synthesis Examples 2 to 7, 13]
The composition shown in Table 1 was synthesized in the same manner as in Synthesis Example 1 to obtain binder resin particles of Synthesis Examples 2-7 and 13.

[Synthesis Example 8]
Reactive ammonia neutralization in a mixture of 14.2 parts of 2-ethylhexyl acrylate, 10 parts of methyl methacrylate, 70 parts of isostearyl acrylate, 0.3 part of trimethylolpropane triacrylate, 1.5 parts of acrylamide and 4.0 parts of acrylic acid Daikin Kogyo Seiyaku Co., Ltd. “AQUALON KH-10” 1.5 parts as a non-ionic anionic surfactant, Daiichi Kogyo Seiyaku Co., Ltd. “Monogen Y-100” 1 as a non-reactive anionic surfactant A solution prepared by dissolving 0.0 part in 100 parts of deionized water was added and stirred to obtain a preliminary emulsion. The above preliminary emulsion was further treated with an ultrasonic homogenizer (Nippon Seiki Seisakusho) for 20 minutes to obtain a pre-emulsion having an average particle size of 0.17 μm.
Separately, 100 parts of ion-exchanged water was charged into a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel, and a refluxer, and the internal temperature was raised to 70 ° C. to sufficiently substitute nitrogen. Thereafter, 10 parts of a 5% aqueous solution of potassium persulfate was added and the reaction system was maintained at 70 ° C. for 5 minutes, and then the pre-emulsion was added dropwise over 2 hours while maintaining the internal temperature at 80 ° C., followed by stirring for 2 hours. Continued. After confirming that the conversion rate exceeded 98% by solid content measurement, the temperature was cooled to 30 ° C. and neutralized by adding 12.0 g of 25% aqueous ammonia to obtain binder resin particles.

[Synthesis Examples 9-12, 14, 15]
The compounding compositions shown in Table 1 were synthesized in the same manner as in Synthesis Example 8 to obtain binder resin particles of Synthesis Examples 9-12, 14, and 15.

AQUALON KH-10: Daiichi Kogyo Seiyaku Reactive Anionic Surfactant Neugen XL-80: Daiichi Kogyo Seiyaku Nonionic Surfactant Monogen Y-100: Daiichi Kogyo Seiyaku Anionic Surfactant

<Creation of non-aqueous secondary battery electrode>
In the present specification, Examples 1 to 7 and 12 are reference examples.
[Examples 1 to 12, Comparative Examples 1 to 3]
(Preparation of positive electrode)
3 parts as a solid content of the binder resin particles obtained in Synthesis Examples 1 to 15, 90 parts of lithium iron phosphate (LiFePO ₄ ) as a positive electrode active material, and acetylene black 5 as a conductive material
2 parts of carboxymethylcellulose was added as a thickener and ion-exchanged water was added so as to have a solid content of 50%, followed by kneading to prepare a composition for a secondary battery electrode. This secondary battery electrode composition was applied onto a 20 μm-thick aluminum foil serving as a current collector using a doctor blade, dried under reduced pressure, and subjected to a rolling process using a roll press to form a 50 μm-thick positive electrode composite. A positive electrode having an agent layer was produced.

(Preparation of negative electrode)
Add 2 parts as the solid content of the binder resin particles obtained in Synthesis Examples 1 to 15, 97 parts of mesophase carbon as the negative electrode active material, and 1 part of carboxymethyl cellulose as the thickener, and ion exchange so that the solid content is 50%. After adding water, the binder composition was prepared by kneading. After applying this binder composition onto a copper foil having a thickness of 20 μm as a current collector using a doctor blade, drying under reduced pressure, performing a rolling process by a roll press, and having a negative electrode mixture layer having a thickness of 50 μm A negative electrode was produced.

<Assembly of lithium secondary battery positive electrode evaluation cell>
The positive electrode produced previously was punched into a diameter of 16 mm, the working electrode was a metallic lithium foil, a separator made of a porous polypropylene film was inserted between the working electrode and the counter electrode, and an electrolyte solution (ethylene carbonate and diethyl carbonate was added). A coin cell was assembled by filling a mixed solvent mixed at a ratio of 1: 1 (volume ratio) with a nonaqueous electrolytic solution in which LiPF ₆ was dissolved at a concentration of 1M. The coin cell was assembled in a glove box substituted with argon gas, and a predetermined battery characteristic evaluation was performed after the cell assembly.

<Assembly of lithium secondary battery negative electrode evaluation cell>
The negative electrode prepared earlier was punched to a diameter of 16 mm, the metal lithium foil was the counter electrode, a separator made of a porous polypropylene film was inserted between the working electrode and the counter electrode, and an electrolyte solution (ethylene carbonate and diethyl carbonate was added). A coin cell was assembled by filling a mixed solvent mixed at a ratio of 1: 1 (volume ratio) with a nonaqueous electrolytic solution in which LiPF ₆ was dissolved at a concentration of 1M. The coin cell was assembled in a glove box substituted with argon gas, and a predetermined battery characteristic evaluation was performed after the cell assembly.

  Using the secondary battery electrode and lithium secondary battery electrode evaluation cell obtained by the above method, the adhesion, flexibility, electrolyte resistance, and battery characteristics were evaluated.

(Adhesion)
Using a knife on the electrode surface, 6 incisions were made from the mixture layer to the depth reaching the current collector, both vertically and horizontally at intervals of 2 mm, to make a grid cut. An adhesive tape was applied to the cut and immediately peeled off, and the degree of the active material falling off was determined by visual judgment. The evaluation criteria are shown below. The evaluation results are shown in Table 2.
A: “No peeling”
○: “Slightly peeled off (a level with no practical problem)”
Δ: “Peeling at most parts”
×: “Completely peeled”

(Electrolytic solution resistance)
The prepared electrode was immersed in a mixed solvent in which ethylene carbonate and diethyl carbonate were mixed at a ratio of 1: 1 (volume ratio) at 70 ° C. for 24 hours, and the swelling state of the film and the elution state of the resin before and after immersion were as follows: Calculation and comparative evaluation were performed.
Swelling ratio (%) = [(weight after immersion) / (weight before immersion)] × 100
Dissolution rate (%) = [1- (weight after immersion drying) / (weight before immersion)] × 100
As the swelling rate is closer to 100% and the dissolution rate is closer to 0%, the resistance to electrolytic solution is higher. The evaluation results are shown in Table 2.
A: “Swelling ratio is less than 150%. Particularly excellent.”
○: “The swelling rate is 150% or more and less than 200%. No problem at all”
Δ: “Swelling rate is 200% or more and less than 300%. Practical use is possible.”
X: “Swelling rate is 300% or more.

A: “Elution rate is less than 1.0%. Particularly excellent.”
○: “Elution rate is 1.0% or more and less than 3.0%. No problem at all”
Δ: “Elution rate is 3.0% or more and less than 10%. Practical use is possible.”
×: “Elution rate is 10% or more.

(Battery characteristics evaluation)
The charge / discharge cycle test of the lithium secondary battery electrode evaluation cell produced above was performed. The discharge capacity at the first time was taken as 100%, and the discharge capacity after 100 hours at 60 ° C. was measured to obtain the rate of change (the closer to 100%, the better). The evaluation results are shown in Table 2.
A: “Change rate is 99% or more. Particularly excellent.”
○: “Change rate is 95% or more and less than 99%. No problem at all”
○: “Change rate is 90% or more and less than 95%. No practical problem”
Δ: “Change rate is 80% or more and less than 90%.
X: “Change rate is less than 80%.

  As shown in Table 2, when the composition for a secondary battery electrode including the binder resin particles prepared in Synthesis Examples 1 to 12 is used, the balance between the electrolytic solution resistance and the adhesiveness is achieved, and the battery characteristics are 60 Even after 100 hours at 100 ° C., the decrease in discharge capacity is suppressed. On the other hand, when the composition for secondary battery electrodes containing the binder resin particles prepared in Synthesis Examples 13 to 15 is used, deterioration of the electrolytic solution resistance, adhesion, and battery characteristics is observed.

Claims (6)

A method for producing a binder resin composition for a non-aqueous secondary battery electrode, in which a monomer mixture is polymerized in an aqueous medium containing a surfactant, a polymerization initiator, and water as essential components,
The monomer mixture contains a radically polymerizable ethylenically unsaturated monomer (A) having a branched alkyl group having 10 to 40 carbon atoms,
A method for producing a binder resin composition for a non-aqueous secondary battery electrode, wherein the monomer mixture is emulsified in the presence of a surfactant and water and then the average particle size is emulsified to 2 μm or less. The monomer mixture contains an ethylenically unsaturated monomer (B) other than the ethylenically unsaturated monomer (A), and the ethylenically unsaturated monomer (B) is an alkoxysilyl group-containing monofunctional group. Ethylenically unsaturated monomer (a), N-methylol group-containing monofunctional ethylenically unsaturated monomer (b), and monomer having two or more ethylenically unsaturated groups in one molecule (c And a monomer (d) having one ethylenically unsaturated group and a cyclic structure in one molecule. The non-aqueous system according to claim 1 The manufacturing method of the binder resin composition for secondary battery electrodes. The method for producing a binder resin composition for a non-aqueous secondary battery electrode according to claim 1 or 2, wherein the ethylenically unsaturated monomer (A) is contained in the monomer mixture in an amount of 5 wt% or more. The ethylenically unsaturated monomer (B) contains 10 to 60 wt% of the monomer (d) having one ethylenically unsaturated group and a cyclic structure in one molecule in the monomer mixture. The manufacturing method of the binder resin composition for non-aqueous secondary battery electrodes of Claim 2 or 3 characterized by the above-mentioned. Nonaqueous secondary, characterized in that there use the claims 1-4 nonaqueous secondary battery electrode binder resin composition obtained by the production method of the nonaqueous secondary battery electrode binder resin composition according to any one of Manufacturing method of battery electrode. Method of manufacturing a nonaqueous secondary battery, characterized in that there use a non-aqueous secondary cell electrode obtained by the process of claim 5 wherein.