JP2008088330A - (meth)acrylic acid-based cross-linked polymer and electrode of secondary battery using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a (meth)acrylic acid-based cross-linked polymer which may have high radical concentration, and a secondary battery using the same. <P>SOLUTION: The (meth)acrylic acid-based cross-linked polymer is prepared by polymerizing a (meth)acrylic acid imino compound expressed by general formula (1) (wherein R expresses H or methyl), if necessary, with a (meth)acrylic acid ester, in the presence of a cross-linking agent. The secondary battery using the same is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a (meth) acrylic acid-based crosslinked polymer and a secondary battery electrode using the same. More specifically, the present invention relates to a (meth) acrylic acid-based crosslinked polymer used as an electrode material of a secondary battery having a high energy density and a large capacity, and a secondary battery electrode using the same.

  With the rapid market expansion of notebook personal computers and mobile phones, there is an increasing demand for small high-capacity secondary batteries with high energy density used for these. In order to meet this demand, a secondary battery using an alkali metal ion such as lithium ion as a charge carrier and utilizing an electrochemical reaction accompanying charge transfer has been developed. Among these, lithium ion secondary batteries are used in various electronic devices as high-capacity secondary batteries having high energy density and excellent stability. Such a lithium ion secondary battery generally uses a lithium-containing transition metal oxide as a positive electrode as an active material and carbon as a negative electrode, and utilizes insertion and desorption reactions of lithium ions into these active materials. Charging and discharging.

In recent years, a secondary battery using a radical compound as an electrode active material that directly contributes to an electrode reaction has been proposed for the purpose of increasing the capacity (see Patent Document 1). Examples of the radical compound include poly (2,2,6,6-tetramethyl-4-piperidinoxymethacrylate) and poly (2,2,5,5-tetramethyl-2-pyrrolidinoxymethacrylate). Further, compounds having a stable radical in the side chain of a polymer such as poly (2,2,5,5-tetramethyl-2-pyrrolinoxymethacrylate) have been proposed. Among these radical compounds, for example, the radical concentration (calculated value) of poly (2,2,5,5-tetramethylpyrrolinoxymethacrylate) having the highest radical concentration is 2.69 × 10 ²¹ radicals / g. .

In addition, a polymer compound having a spiro cyclic nitroxide structure has been proposed as a radical compound having a high radical concentration (see Patent Document 2). Among the polymer compounds, the radical concentration of poly (2,2,8,8,10,10-hexamethyl-1,9-diazaspiro [5,5] -undecane acrylateoxy radical) having the highest radical concentration (calculation) Value) is 3.56 × 10 ²¹ radicals / g, and Patent Document 2 describes that the radical concentration (measured value) of this polymer compound is 3.58 × 10 ²¹ radicals / g. Yes.

  The radical concentration is one of the important indexes for realizing a secondary battery having a high energy density and a large capacity. Therefore, the radical concentration is used as an electrode active material including a radical compound having a high radical concentration. The emergence of various radical compounds that can be expected is awaited.

JP 2002-304996 A JP 2006-45310 A

  An object of the present invention is to provide a (meth) acrylic acid-based crosslinked polymer having a high radical concentration and an electrode of a secondary battery using the same.

  The (meth) acrylic acid-based crosslinked polymer according to the present invention has the general formula (1):

（式（１）中、Ｒは、水素原子またはメチル基を示す。）で表される（メタ）アクリル酸イミノ化合物を、要すれば（メタ）アクリル酸エステルと共に、架橋剤の存在下で重合した後、ニトロキシド化して得られるものである。

(In formula (1), R represents a hydrogen atom or a methyl group.) A (meth) acrylic acid imino compound represented by the formula is polymerized in the presence of a crosslinking agent together with a (meth) acrylic acid ester if necessary. Then, it is obtained by nitroxide formation.

  Examples of the (meth) acrylic acid ester include hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and (meth) acrylic. It is at least one selected from the group consisting of acid behenyl. Moreover, the usage-amount of the said (meth) acrylic acid ester is a ratio of 0.00001-0.25 mol normally with respect to 1 mol of (meth) acrylic-acid imino compounds.

  Examples of the crosslinking agent used in the (meth) acrylic acid-based crosslinked polymer according to the present invention include ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,6-hexanediol di ( It is at least one selected from the group consisting of (meth) acrylate, 1,8-octanediol di (meth) acrylate and 1,9-nonanediol di (meth) acrylate.

  Moreover, the polymerization method in the (meth) acrylic acid-based crosslinked polymer according to the present invention is, for example, a suspension polymerization method or an emulsion polymerization method.

  The electrode of the secondary battery according to the present invention uses the (meth) acrylic acid-based crosslinked polymer.

  In the present invention, acrylic acid and methacrylic acid are referred to as (meth) acrylic acid, and methacrylate and acrylate are referred to as (meth) acrylate.

  According to the present invention, a (meth) acrylic acid-based crosslinked polymer having a high radical concentration, useful as an electrode active material for a secondary battery, and an electrode for a secondary battery having a high energy density and a large capacity are provided. can do.

  The capacity of a secondary battery using a radical compound as an electrode active material is given by the following formula.

C (Ah / kg) = N _A · e / (3600 · M / 1000)
(Wherein, C is the capacitance, N _A is the molar constant, e is the electronic charge, M denotes a molecular weight per radical.)
For example, the capacity of the active material of the lithium ion battery is 130 to 160 Ah / kg, and the radical concentration of the (meth) acrylic acid-based crosslinked polymer according to the present invention is, for example, 3.85 to 4.46. Since it is × 10 ²¹ radicals / g (calculated value), the realization of a large capacity electrode active material of 190 to 196 Ah / kg (calculated value) can be expected.

  The (meth) acrylic acid-based crosslinked polymer according to the present invention is a (meth) acrylic acid imino compound represented by the following general formula (1), if necessary, together with a (meth) acrylic acid ester, in the presence of a crosslinking agent. It is obtained by nitroxide formation after polymerization.

一般式（１）中、Ｒは、水素原子またはメチル基を示す。

In general formula (1), R represents a hydrogen atom or a methyl group.

  For example, the (meth) acrylic acid imino compound used in the present invention is 2,4-diazido-2,4-dimethyl by a known method (US Pat. No. 5,847,120) using 2,4-dimethyl-3-pentanone. After obtaining -3-pentanone, dehydration reaction of this with acetone in an equimolar amount using an alcohol solvent is carried out by formula (2):

で表されるアミノケトン化合物を得て、次いでこれをナトリウムボロハイドライド等の還元剤を用いて還元させることにより、式（３）：

And then reducing this with a reducing agent such as sodium borohydride to obtain the formula (3):

で表されるアミノアルコール化合物を得て、さらにこれを、トリエチルアミン等の塩基の存在下に（メタ）アクリル酸クロライド等の（メタ）アクリル酸ハライドでエステル化させる方法や、あるいはチタン酸テトラメチル等の触媒の存在下に（メタ）アクリル酸メチル等の（メタ）アクリル酸エステル化合物とエステル交換させる方法により得ることができる。

And a method of esterifying it with a (meth) acrylic acid halide such as (meth) acrylic acid chloride in the presence of a base such as triethylamine, or tetramethyl titanate, etc. It can obtain by the method of transesterifying with (meth) acrylic acid ester compounds, such as methyl (meth) acrylate, in presence of the catalyst of this.

  The (meth) acrylic acid-based crosslinked polymer according to the present invention is a (meth) acrylic acid ester obtained as described above and represented by the general formula (1). At the same time, the polymerization reaction product obtained by polymerization in the presence of a crosslinking agent can be produced by further nitroxide formation.

  The (meth) acrylic acid imino compound has a relatively low molecular weight and can have a plurality of radical sites by nitroxidation. Therefore, the (meth) acrylic acid-based cross-linking polymer of the present invention having this as a repeating unit is used. The coalescence can have a high radical concentration. In such a polymer, a polymer that does not have a crosslinked structure, that is, a (meth) acrylic acid polymer obtained without using a crosslinking agent can also have a high radical concentration. However, such a (meth) acrylic acid-based polymer having no cross-linking structure is easily dissolved in a solvent constituting an electrolyte solution for transporting charge carriers between the positive electrode and the negative electrode in a secondary battery or the like. Therefore, a secondary battery using this as an electrode active material may not be able to fully exhibit its performance. Examples of the solvent constituting the electrolytic solution include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxofuran, sulfolane, dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone. These organic solvents are used alone or in admixture of two or more. On the other hand, the (meth) acrylic acid-based cross-linked polymer according to the present invention has a cross-linked structure, is suppressed in solubility in the solvent constituting the electrolytic solution, and has excellent characteristics with respect to solvent stability.

  The crosslinking agent used in the (meth) acrylic acid-based crosslinked polymer according to the present invention is not particularly limited as long as it is a compound having a plurality of polymerizable unsaturated groups in the molecule. For example, (meth) acrylic acid A polyfunctional compound, an allyl ether polyfunctional compound, a vinyl polyfunctional compound, and the like. Examples of the (meth) acrylic acid polyfunctional compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3-propanediol di (meth) acrylate, 1 , 3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,5-pentanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,7 -Heptanediol di (meth) acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, trimethylolpropane tri ( (Meth) acrylate, glycerin (Meth) acrylate and 2-hydroxy-3- (meth) acryloyloxy propyl (meth) acrylate. Examples of the allyl ether polyfunctional compound include diethylene glycol diallyl ether and dibutylene glycol diallyl ether. Examples of the vinyl polyfunctional compound include divinylbenzene. Among these, from the viewpoint of having high polymerization reactivity, a (meth) acrylic acid polyfunctional compound is preferably used, and in particular, ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,8-octanediol di (meth) acrylate and 1,9-nonanediol di (meth) acrylate are preferably used. In addition, these crosslinking agents can be used individually by 1 type or in combination of 2 or more types, respectively.

  The proportion of the crosslinking agent used is such that the (meth) acrylic acid imino compound 1 is obtained from the viewpoint of obtaining a (meth) acrylic acid-based crosslinked polymer having excellent solvent stability and obtaining an effect corresponding to the amount used. It is preferably a ratio of 0.00001 to 0.25 mol, more preferably a ratio of 0.00005 to 0.1 mol, and a ratio of 0.0001 to 0.05 mol. Is more preferable.

  In the present invention, the (meth) acrylic acid-based crosslinked polymer obtained by using a (meth) acrylic acid ester together with a (meth) acrylic acid imino compound has not only excellent solvent stability but also high coating properties. Have That is, the cross-linked polymer can be formed into a paint with a relatively small amount of solvent in a coating process required when applied as an electrode active material for a secondary battery or the like. No cracks occur. If cracks occur in an electrode manufactured by applying the paint to a current collector and drying it, the workability of the electrode in subsequent secondary battery manufacturing will be impaired, or the capacity of the secondary battery will be reduced. May occur. In the cross-linked polymer, the reason why it has such a high coating property and can suppress cracking during drying is not clear, but the repulsion between the introduced alkyl groups causes the solvent to move between the molecular chains. This is considered to be because the fluidity of the slurry is improved from before the introduction of the alkyl group.

  Although it does not specifically limit as said (meth) acrylic acid ester, For example, (meth) acrylic-acid alkylester, polyalkylene glycol mono (meth) acrylate, etc. are mentioned. Although it does not specifically limit as (meth) acrylic-acid alkylester, For example, (meth) acrylic-acid methyl, (meth) acrylic-acid ethyl, (meth) acrylic-acid propyl, (meth) acrylic-acid isopropyl, Examples include butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and behenyl (meth) acrylate. It is done. On the other hand, the polyalkylene glycol mono (meth) acrylate is not particularly limited, and examples thereof include polyethylene glycol mono (meth) acrylate and polypropylene glycol mono (meth) acrylate. Moreover, as a magnitude | size of a polyalkylene glycol part, the number of repetitions of an alkylene glycol part is 1-100, for example. Among these, the (meth) acrylic acid alkyl ester is preferably used because of the excellent application ease when the obtained (meth) acrylic acid-based crosslinked polymer is made into a paint, and among these, (meth) acrylic Hexyl acid, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and behenyl (meth) acrylate are preferably used, and stearyl (meth) acrylate Is particularly preferably used. In addition, these (meth) acrylic acid ester can be used individually by 1 type or in combination of 2 or more types, respectively.

  The use ratio in the case of using the (meth) acrylic acid ester is the above (meth) from the viewpoint of obtaining a good coating surface of the (meth) acrylic acid-based crosslinked polymer and obtaining an effect that is commensurate with the amount used. The ratio is preferably 0.25 mol or less, more preferably 0.00005 to 0.1 mol, and more preferably 0.001 to 0.05 mol with respect to 1 mol of the acrylic acid imino compound. More preferably it is.

  The polymerization method used in the (meth) acrylic acid-based crosslinked polymer according to the present invention is not particularly limited, and for example, a suspension polymerization method, an emulsion polymerization method, a solution polymerization method, or the like is used. Can do.

  As the suspension polymerization method, for example, using a reactor equipped with a stirrer, a thermometer, a nitrogen gas introduction pipe and a cooling pipe, a predetermined amount of (meth) acrylic acid imino compound, a crosslinking agent, an oil-soluble radical polymerization initiator If necessary, mix (meth) acrylic acid ester with an inert hydrocarbon solvent and a surfactant mixed with water that is inert to the reaction, and then disperse with nitrogen gas. And heating with stirring.

  The oil-soluble radical polymerization initiator used in the suspension polymerization method is not particularly limited, and examples thereof include benzoyl peroxide, tert-butyl peroxide, lauroyl peroxide, diisopropyl peroxydicarbonate and dicyclohexyl peroxydicarbonate. Peroxide-based polymerization initiators; azo such as α, α′-azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile and dimethyl-2,2′-azobisisobutyrate Examples thereof include redox polymerization initiators such as benzoyl peroxide / dimethylaniline, di-tert-butyl peroxide / dimethylaniline peroxide, and lauroyl peroxide / dimethylaniline. Among these, an azo polymerization initiator such as α, α'-azobisisobutyronitrile, which is inexpensive and easy to handle, is preferably used.

  The amount of the oil-soluble radical polymerization initiator used in the suspension polymerization method varies depending on the type of the oil-soluble radical polymerization initiator used and the reaction temperature, but is usually 100 parts by weight of the (meth) acrylic acid imino compound. 0.005 to 5 parts by weight.

  The inert hydrocarbon solvent used in the suspension polymerization method is not particularly limited. For example, an aromatic hydrocarbon solvent such as benzene, toluene and xylene; acyclic such as n-hexane, n-heptane and ligroin Saturated hydrocarbon solvents; cyclic saturated hydrocarbon solvents such as cyclopentane, methylcyclopentane, cyclohexane and methylcyclohexane; halogenated hydrocarbon solvents such as dichloromethane, chloroform and dichloroethane. Among these, an aromatic hydrocarbon solvent and an acyclic saturated hydrocarbon solvent are preferable from the viewpoint of being easily available industrially, inexpensive, and stabilizing the quality of the obtained polymerization reaction product. Toluene and n-hexane are preferably used.

  The amount of the inert hydrocarbon solvent used in the suspension polymerization method is from the viewpoint of sufficiently dissolving the (meth) acrylic acid imino compound and allowing the polymerization reaction to proceed smoothly and obtaining an effect that is commensurate with the amount used. It is preferable that it is 50-300 weight part with respect to 100 weight part of (meth) acrylic-acid imino compounds, and it is more preferable that it is 100-200 weight part.

  As the surfactant used in the suspension polymerization method, any of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant can be used.

  Examples of the anionic surfactant used in the suspension polymerization method include fatty acid sodium, aliphatic potassium, sodium alkyl sulfate, sodium alkylbenzene sulfonate, sodium alkane sulfonate, sodium alkyl phosphate, acyloyl methyl taurate, N -Sodium methyl-N-acylamide propionate, sodium monoalkylbiphenyl ether disulfonate, sodium naphthalene sulfonate-formalin condensate, sodium acyl glutamate, sodium polyoxyethylene alkylphenyl ether alkylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate , Sodium polyoxyethylene alkyl ether methylcarboxylate and polyoxyethylene alkyl ether ethanesulfur Sodium phosphate, and the like.

  Examples of the cationic surfactant used in the suspension polymerization method include monoalkyl trimethyl ammonium methosulfate, cationized cellulose, alkyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, dialkyl dimethyl ammonium chloride, dialkyl dimethyl benzyl ammonium chloride and Examples include alkylpyridinium chloride.

  Nonionic surfactants used in the suspension polymerization method include, for example, fatty acid monoglyceride, sorbitan fatty acid partial ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid monoglyceride, polyoxyethylene sorbitol fatty acid moiety Ester, polyoxyethylene sorbitan fatty acid partial ester, polyoxyethylene lanolin alcohol ether, polyethylene glycol fatty acid monoester, polyethylene glycol fatty acid diester, polyoxyethylene fatty acid amine, polyglycerin fatty acid partial ester, bis (2-hydroxyethyl) alkylamine, Alkyldimethylamine oxide, fatty acid alkylolamide, ω-methoxypolyoxyethylene-α-a Examples include alkyl ether, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene acetylene glycol, sugar fatty acid partial ester, polyvinyl alcohol, and partially saponified polyvinyl alcohol.

  Examples of the amphoteric surfactant used in the suspension polymerization method include N-acylamidopropyl-N, N-dimethylammoniobetaine, N-acylamidopropyl-N ′, N′-dimethyl-N′-β- Hydroxypropylammoniosulfobetaine, N-acylamidoethyl-N′-hydroxyethyl-N′-carboxymethylammoniobetaine, N-alkyl-N-dimethyl-N-carboxymethylammoniobetaine, alkyldiaminoethylglycine and acyl And modified polypeptides.

  Among these surfactants, industrially easy to obtain, inexpensive, and from the viewpoint of stabilizing the quality of the resulting polymerization reaction product, sodium alkylbenzene sulfonate, sodium polyoxyethylene alkylphenyl ether alkylbenzene sulfonate, Polyvinyl alcohol and partially saponified polyvinyl alcohol are preferably used. Among sodium alkylbenzenesulfonates, sodium dodecylbenzenesulfonate is preferable, and among sodium polyoxyethylene alkylphenylether alkylbenzenesulfonates, sodium polyoxyethylenenonylphenylether dodecylbenzenesulfonate is preferable.

  The amount of the surfactant used in the suspension polymerization method is 0.05 to 10 parts by weight with respect to 100 parts by weight of the water from the viewpoint of smoothly proceeding the reaction and obtaining an effect that is commensurate with the amount of use. It is preferable that it is 0.1-5 weight part.

  The amount of water used in the suspension polymerization method is 100 to 3000 weights with respect to 100 parts by weight of the (meth) acrylic acid imino compound from the viewpoint of sufficiently removing the heat of polymerization and making it easy to control the polymerization temperature. Parts, preferably 200 to 2000 parts by weight.

  In the suspension polymerization reaction, additives such as a chain transfer agent such as isopropyl alcohol and a polymerization terminator such as methanol may be added as necessary.

  The reaction temperature in the suspension polymerization method is preferably 30 to 100 ° C, more preferably 40 to 80 ° C. Since the reaction time varies depending on the reaction temperature, it cannot be generally stated, but is usually 0.5 to 10 hours.

  Since the polymerization reaction product thus obtained exists in a particle state in the reaction solvent, it can be isolated by filtering the reaction solution. Furthermore, it can be purified by removing unreacted substances, washing and drying using water, methanol, hexane or the like.

  As an emulsion polymerization method, which is another polymerization method used in the (meth) acrylic acid-based crosslinked polymer according to the present invention, for example, a reactor equipped with a stirrer, a thermometer, a nitrogen gas introduction pipe and a cooling pipe is used. Then, a predetermined amount of (meth) acrylic acid imino compound, a crosslinking agent, a surfactant and, if necessary, (meth) acrylic acid ester are mixed and dispersed in water as an inert solvent, and then removed with nitrogen gas. There is a method in which oxygen is added, a water-soluble radical polymerization initiator is added, and the mixture is heated with stirring.

  The water-soluble radical polymerization initiator used in the emulsion polymerization method is not particularly limited, and examples thereof include peroxide polymerization initiators such as ammonium persulfate, sodium persulfate, and potassium persulfate; ferrous ammonium sulfate / ammonium persulfate and Examples thereof include redox polymerization initiators such as ethanolamine / potassium persulfate. Among these, peroxide polymerization initiators such as potassium persulfate, which are inexpensive and easy to handle, are preferably used.

  In the emulsion polymerization method, the type and amount of the surfactant used, the amount of polymerization initiator used, the amount of water used as the inert solvent, the reaction temperature and the reaction time are the same as those in the suspension polymerization method. Things can be applied.

  In the emulsion polymerization method, an inert hydrocarbon solvent similar to that used in the suspension polymerization method may be appropriately added to dissolve the (meth) acrylic acid imino compound. You may add suitably additives, such as chain transfer agents, such as alcohol, and polymerization terminators, such as methanol.

  The polymerization reaction product thus obtained can be isolated, for example, by mixing the reaction solution with a large amount of cold water and precipitating the polymerization reaction product, followed by filtration. Furthermore, it can be purified by removing unreacted substances, washing and drying using water, methanol, hexane or the like.

  The solution polymerization method, which is still another polymerization method used in the (meth) acrylic acid-based crosslinked polymer according to the present invention, includes, for example, a reactor equipped with a stirrer, a thermometer, a nitrogen gas introduction tube and a cooling tube. Use a specified amount of (meth) acrylic acid imino compound, cross-linking agent, inert solvent and (meth) acrylic acid ester if necessary, deoxygenate with nitrogen gas, then add polymerization initiator while stirring The method of doing is mentioned.

  The inert solvent used in the solution polymerization method is not particularly limited, and examples thereof include aromatic hydrocarbon solvents such as benzene, toluene and xylene; acyclic saturated hydrocarbon systems such as n-hexane, n-heptane and ligroin Solvent: Cyclic saturated hydrocarbon solvents such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, etc .; Inert solvents such as ether solvents such as diethyl ether and tetrahydrofuran. Among these, aromatic hydrocarbon solvents and acyclic saturated hydrocarbon solvents are preferred from the viewpoint of being easily available industrially, inexpensive, and stabilizing the quality of the resulting polymerization reaction product. And n-hexane are preferably used.

  The amount of the inert solvent used in the solution polymerization method is 50 to 2000 with respect to 100 parts by weight of the (meth) acrylic acid imino compound from the viewpoint of smoothly proceeding the reaction and obtaining an effect sufficient for the amount of use. It is preferable that it is a weight part.

  It does not specifically limit as a polymerization initiator used for a solution polymerization method, It can superpose | polymerize using a radical polymerization initiator and an anionic polymerization initiator. Examples of the radical polymerization initiator include peroxide polymerization initiators such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, tertiary butyl hydroperoxide, and potassium persulfate; α, α′-azobis Azo polymerization initiators such as isobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, dimethyl-2,2′-azobisisobutyrate; ferrous ammonium sulfate / ammonium persulfate, ethanol Examples include redox polymerization initiators such as amine / potassium persulfate and sodium bromate / sulfur dioxide. Among these, an azo polymerization initiator such as α, α'-azobisisobutyronitrile, which is inexpensive and easy to handle, is preferably used. Examples of the anionic polymerization initiator include Grignard reagents (n-butylmagnesium bromide, isobutylmagnesium bromide, tert-butylmagnesium bromide, n-butylmagnesium chloride, isobutylmagnesium chloride, tert-butylmagnesium chloride) and alkyls. And lithium (n-butyllithium, tert-butyllithium, 1,1, -diphenylhexyllithium, etc.) and the like. Among these, alkyllithium such as tert-butyllithium is preferably used from the viewpoint of stabilizing the quality of the obtained polymerization reaction product.

  The amount of the polymerization initiator used in the solution polymerization method varies depending on the type of polymerization initiator used and the reaction temperature, but is usually 0.005 to 5 parts by weight with respect to 100 parts by weight of the (meth) acrylic acid imino compound. It is.

  In the solution polymerization reaction, additives such as a chain transfer agent such as isopropyl alcohol and a polymerization terminator such as methanol may be added as necessary.

  The reaction temperature in the solution polymerization method varies depending on the type of polymerization initiator used, but is usually preferably −100 to 100 ° C., more preferably −50 to 80 ° C. Although the reaction time varies depending on the reaction temperature, it cannot be generally stated, but it is usually 2 to 10 hours.

  The polymerization reaction product thus obtained can be isolated by mixing the reaction solution with a solvent such as an aliphatic hydrocarbon such as hexane to precipitate the polymerization reaction product, followed by filtration. Furthermore, it can refine | purify by removing unreacted substance etc. using methanol, hexane, etc., wash | cleaning, and drying.

  The (meth) acrylic acid-based crosslinked polymer according to the present invention can be produced by nitrating the polymerization reaction product obtained as described above.

  The method for nitrating the polymerization reaction product is not particularly limited. For example, a compound having a corresponding nitroxide free radical is produced by oxidizing a secondary amine having steric hindrance using an oxidizing agent. The publicly known method etc. which can be mentioned can be mentioned. Specifically, for example, the polymerization reaction product can be nitrated by mixing the polymerization reaction product and an inert solvent and then reacting with stirring while adding an oxidizing agent.

  Examples of the inert solvent used for nitroxidation include halogenated hydrocarbons such as dichloromethane, chloroform and dichloroethane; aliphatic nitriles such as acetonitrile, propionitrile and butyronitrile; aromatic nitriles such as benzonitrile and tolunitrile. Alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol and tert-butanol; aromatic hydrocarbons such as benzene, toluene and xylene; and water. Among these, halogenated hydrocarbons such as dichloromethane, chloroform and dichloroethane and alcohols such as methanol, ethanol and tert-butanol are preferably used.

  The amount of the inert solvent used for the nitroxide formation is 50 to 5000 parts by weight with respect to 100 parts by weight of the polymerization reaction product from the viewpoint of smoothly proceeding the reaction and obtaining an effect sufficient for the amount of use. It is preferable that it is 100 to 3000 parts by weight.

  Examples of the oxidizing agent used for nitroxidation include peroxides such as hydrogen peroxide, performic acid, peracetic acid, perbenzoic acid and perphthalic acid, halides thereof, silver oxide, lead tetraacetate, hexacyanoiron ( III) Oxides such as potassium acid and potassium permanganate, and air.

  The proportion of the oxidizing agent used for the nitroxide formation is the (meth) acrylic acid imino compound 1 used for the production of the polymerization reaction product from the viewpoint of smoothly proceeding the reaction and obtaining an effect sufficient for the amount used. The ratio is preferably from 1 to 200 mol, more preferably from 1.5 to 100 mol, based on mol.

  In the nitroxidation reaction, a catalyst can be used as necessary. As a catalyst, the catalyst currently used for normal nitroxide-ized reaction can be mentioned. Specific examples of the catalyst used in the nitroxidation reaction include a compound containing a metal element selected from Group 6 of the Group 18 element periodic table such as tungsten and molybdenum. For example, tungstic acid, phosphotungstic acid, para Tungstic acid and alkali metal salts thereof (sodium salt, potassium salt, etc.) and ammonium compounds, tungsten oxides such as tungsten oxide and tungsten carbonyl; molybdic acid, phosphomolybdic acid, paramolybdic acid and alkali metal salts thereof (sodium salt, Potassium salts, etc.) and ammonium compounds, molybdenum oxides, molybdenum compounds such as molybdenum carbonyl, etc., and more specifically, ammonium paratungstate, sodium tungstate, phosphotungstic acid, sodium molybdate. Potassium, molybdenum trioxide and molybdenum hexacarbonyl, and the like.

  The amount of the catalyst used in the nitroxide reaction is 0.001 to 20 parts by weight with respect to 100 parts by weight of the polymerization reaction product from the viewpoint of smoothly proceeding the reaction and obtaining an effect that is commensurate with the amount of use. It is preferable that it is 0.01-10 weight part.

  The reaction temperature for nitroxidation is preferably 0 to 100 ° C, more preferably 20 to 80 ° C.

  Examples of the operating method of nitroxide include a method in which a predetermined amount of a polymerization reaction product, an inert solvent, and a catalyst as necessary are mixed, and then reacted while adding an oxidizing agent with stirring. . According to this method, the reaction can be easily performed with a high yield. In this method, the reaction time while adding the oxidizing agent is not particularly limited, but is usually 1 to 10 hours, preferably 3 to 6 hours. Furthermore, after completion of the addition of the oxidizing agent, the reaction is usually completed by maintaining the temperature for 1 to 10 hours.

  The (meth) acrylic acid-based crosslinked polymer of the present invention thus obtained can be isolated from the reaction solution by combining filtration and drying. In the nitroxidation reaction, it is not always necessary to dissolve the polymerization reaction product in an inert solvent. For example, the nitroxide reaction proceeds easily even in a swollen state.

  The reaction rate of nitroxidation is usually 90% or more, and the reaction rate is determined by a method for analyzing the remaining amount of the oxidizing agent used in the reaction, an amino acid remaining in the reaction product using an NMR method or the like. It can be calculated by a method of quantifying the group.

  By using the (meth) acrylic acid-based crosslinked polymer according to the present invention and binding it to a current collector, an electrode of a secondary battery can be produced.

  The current collector is an electrode component that collects charges generated from the electrodes of the secondary battery and is made of a conductor. Examples of the member used for the current collector usually include metal stays such as nickel, aluminum, copper, gold, silver, aluminum alloy, and stainless steel, metal flat plates and metal meshes, and carbon bars.

  The method for producing the electrode of the secondary battery according to the present invention includes, for example, a coating step for coating the (meth) acrylic acid-based crosslinked polymer and a coating step for applying the coating to the current collector. A method can be mentioned. There is no restriction | limiting in particular in the method of the said coating and the method of application | coating, It can carry out using a well-known method and apparatus.

  Examples of the coating method include a method of mixing a (meth) acrylic acid-based crosslinked polymer with a binder and then adding a solvent to form a slurry. Specific examples of the binder include, for example, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, polypropylene, polyethylene, polyimide, and various polyurethanes. And a resin binder. Specific examples of the solvent include dimethylformamide and N-methylpyrrolidone.

  In addition, as a method of coating, for example, the slurry obtained by the coating is dropped on the surface of the current collector, developed with a wire bar so as to have a uniform thickness, and then dried to remove the solvent. The method of removing is mentioned.

  In addition, an auxiliary conductive material or an ion conduction auxiliary agent may be appropriately added to the (meth) acrylic acid-based crosslinked polymer for the purpose of lowering impedance when forming the paint. Specific examples of the auxiliary conductive material include carbonaceous fine particles such as graphite, carbon black, and acetylene black, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene. Specific examples of the ionic conduction aid include a polymer gel electrolyte and a polymer solid electrolyte.

  The film thickness of the coating film obtained by applying the paint (meth) acrylic acid-based crosslinked polymer is preferably 10 to 1000 μm, and more preferably 50 to 300 μm.

  The electrode of the secondary battery according to the present invention can be suitably used as an electrode of a secondary battery having a high energy density and a large capacity, such as a lithium ion secondary battery.

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

Production Example 1
To a 5 L four-necked flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser tube, 144.2 g (1 mol) of 2,4-diamino-2,4-dimethyl-3-pentanone, acetone 58 .1 g (1 mol) and 1.5 L of methanol were charged, and the oxygen in the reaction system was removed through nitrogen gas while maintaining the temperature at 25 ° C., and then the reaction was carried out at 60 ° C. for 8 hours with stirring. After completion of the reaction, the reaction solution was concentrated under reduced pressure at 35 ° C., and the concentrate was dissolved in 500 mL of a chloroform-methanol mixture (volume ratio 5/1). This solution was purified by passing through a 10 L column filled with 12 L of silica gel (produced by Daiso Corporation, IR-60-63 / 210) suspended in 12 L of a chloroform-methanol mixed solution (volume ratio 5/1). The target fraction was collected and dried under reduced pressure at 35 ° C. until a constant weight was obtained, thereby obtaining 156.8 g of an aminoketone compound.

  Next, 36.8 g (200 mmol) of the resulting aminoketone compound, 3.8 g (100 mmol) of sodium borohydride and 300 mL of methanol were added to a 1 L volume equipped with a stirrer, a nitrogen gas inlet tube, a thermometer and a reflux condenser. The oxygen in the reaction system was removed through nitrogen gas while maintaining the temperature at 25 ° C., and the mixture was reacted for 18 hours with stirring. After completion of the reaction, the reaction solution was concentrated under reduced pressure at 25 ° C., and the concentrate was dissolved in 100 mL of a chloroform-methanol mixture (volume ratio 5/1). This solution was purified by passing through a 1 L column packed with 1.2 mL of a chloroform-methanol mixture (volume ratio 5/1) 300 mL of silica gel (Daiso Co., Ltd., IR-60-63 / 210). did. The target fraction was collected and dried under reduced pressure at 25 ° C. until a constant weight was obtained, thereby obtaining 20.6 g of an amino alcohol compound.

  The obtained amino alcohol compound 18.63 g (100 mmol), methyl methacrylate 40.00 g (400 mmol) and tetramethyl titanate 0.0086 g (0.05 mmol) After charging into a one-necked flask and removing oxygen in the reaction system through nitrogen gas, a 6-hour transesterification reaction was carried out using a reflux apparatus equipped with a 20-stage Oldershaw distillation column. During this time, methanol produced by the reaction was removed out of the system by azeotropy with methyl methacrylate. Moreover, the temperature of the reaction liquid rose from 105 ° C to 118 ° C.

  After completion of the reaction, the reaction solution was concentrated under reduced pressure. After adding 100 mL of hexane to the obtained crystals, water was added in an appropriate amount to deactivate tetramethyl titanate, and after filtering this, hexane was further reduced under reduced pressure. By removing, 24.93 g of an imino methacrylate compound was obtained.

Example 1
In an Erlenmeyer flask having an internal volume of 200 mL, 25.4 g (100 mmol) of the imino methacrylate compound obtained in the same manner as in Production Example 1, 0.3 g (1.0 mmol) of 1,9-nonanediol dimethacrylate, α, α '-Azobisisobutyronitrile (0.115 g, 0.7 mmol) and toluene (35 mL) were charged and mixed to obtain a homogeneous solution.

  Next, in a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, and a reflux condenser tube, 200 mL of water and 0.3 g of sodium dodecylbenzenesulfonate as a surfactant were charged and mixed. While maintaining the solution at 25 ° C., the homogeneous solution was added and dispersed with stirring. Subsequently, oxygen in the reaction system was removed through nitrogen gas, followed by suspension polymerization reaction at 60 ° C. with stirring for 6 hours. After completion of the reaction, the reaction solution was cooled to room temperature, filtered, washed with 500 mL of water and then with 500 mL of hexane, and dried under reduced pressure to obtain 25.2 g of a polymerization reaction product as a white powder (yield 98). .1%).

When the H-NMR (CDCl ₃ ) of the polymerization reaction product of the obtained white powder was measured, 6.21, 1.97, 1.86, 1.63, 1.47, 1.44, 1. Peaks were observed at 34, 1.30, 1.27, and 1.21 ppm.

  Next, 10 g of the obtained polymerization reaction product and 300 mL of methanol were charged into a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, a reflux condenser, and a dropping funnel, and kept at 25 ° C. After removing oxygen in the reaction system through nitrogen gas, 50.4 g (445 mmol) of a 30% hydrogen peroxide solution was added dropwise over 3 hours. Subsequently, after maintaining at 25 ° C. for 8 hours, the reaction solution was filtered, washed with 500 mL of methanol and then with 500 mL of water, and then dried under reduced pressure to obtain 9.5 g of a red powdery methacrylic acid-based crosslinked polymer. .

Example 2
In an Erlenmeyer flask having an internal volume of 200 mL, 25.4 g (100 mmol) of an imino methacrylate compound obtained in the same manner as in Production Example 1, 0.3 g (1.0 mmol) of 1,9-nonanediol dimethacrylate, methacrylic acid- n-stearyl 0.7 g (2.0 mmol), α, α′-azobisisobutyronitrile 0.115 g (0.7 mmol) and toluene 35 mL were charged and mixed to obtain a homogeneous solution.

  Next, in a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, and a reflux condenser tube, 200 mL of water and 0.3 g of sodium dodecylbenzenesulfonate as a surfactant were charged and mixed. While maintaining the solution at 25 ° C., the homogeneous solution was added and dispersed with stirring. Subsequently, oxygen in the reaction system was removed through nitrogen gas, followed by suspension polymerization reaction at 60 ° C. with stirring for 6 hours. After completion of the reaction, the reaction solution was cooled to room temperature, filtered, washed with 500 mL of water and then with 500 mL of hexane, and dried under reduced pressure to obtain 25.7 g of a white powder polymerization reaction product (yield 97). .5%).

The polymerization reaction product of the obtained white powder was measured for H-NMR (CDCl ₃ ), and found to be 6.23, 3.92, 1.95, 1.88, 1.62, 1.47, 1. Peaks were observed at 43, 1.36, 1.30, 1.27, and 1.23 ppm.

  Next, 10 g of the obtained polymerization reaction product and 300 mL of methanol were charged into a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, a reflux condenser, and a dropping funnel, and kept at 25 ° C. After removing oxygen in the reaction system through nitrogen gas, 50.4 g (445 mmol) of a 30% hydrogen peroxide solution was added dropwise over 3 hours. Subsequently, after maintaining at 25 ° C. for 8 hours, the reaction solution was filtered, washed with 500 mL of methanol and then with 500 mL of water, and then dried under reduced pressure to obtain 9.7 g of a red powdery methacrylic acid-based crosslinked polymer. .

Example 3
In Example 2, a white powder polymerization reaction product 24 was obtained in the same manner as in Example 2 except that 0.3 g of polyvinyl alcohol (degree of polymerization: 2000) was used instead of 0.3 g of sodium dodecylbenzenesulfonate. 0.4 g was obtained (92.4% yield).

When the H-NMR (CDCl ₃ ) of the obtained white powder polymerization reaction product was measured, it was 6.23, 3.92, 1.95, 1.88, 1.64, 1.47, 1. Peaks were observed at 43, 1.36, 1.33, 1.27, and 1.23 ppm.

  Next, 10 g of the obtained polymerization reaction product, 0.7 g (2.2 mmol) of sodium tungstate dihydrate as a catalyst, and 300 mL of methanol were mixed with a stirrer, a nitrogen gas introduction pipe, a thermometer, a reflux condenser and After charging in a 500 mL four-necked flask equipped with a dropping funnel and removing oxygen in the reaction system through nitrogen gas while maintaining at 25 ° C., 50.4 g (445 mmol) of 30% hydrogen peroxide solution was added for 3 hours. The reaction solution was filtered, washed with 500 mL of methanol and then with 500 mL of water, and then dried under reduced pressure to obtain a red powdery methacrylic acid-based crosslinked polymer 9. .8 g was obtained.

Example 4
In a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser, 50.9 g (200 mmol) of an imino methacrylate compound obtained in the same manner as in Production Example 1, 1,9 -1.3 g (4.0 mmol) of nonanediol dimethacrylate, 0.7 g (2.0 mmol) of methacrylic acid-n-stearyl, 0.3 g of sodium polyoxyethylene nonylphenyl ether dodecylbenzenesulfonate as a surfactant And 140 mL of water were added and stirred at 65 ° C. for 1 hour to obtain a uniform solution. Subsequently, after removing oxygen in the reaction system through nitrogen gas, 0.379 g (1.4 mmol) of potassium persulfate as a polymerization initiator was added, and an emulsion polymerization reaction was performed at 70 ° C. for 6 hours with stirring. It was. After completion of the reaction, the reaction solution was cooled to room temperature, added to 2000 mL of cold water at 5 ° C., further filtered, washed with 500 mL of water, and dried under reduced pressure to obtain 48.9 g of a polymerization reaction product as a white powder. Obtained (yield 92.5%).

The polymerization reaction product of the obtained white powder was measured for H-NMR (CDCl ₃ ), and found to be 6.23, 3.92, 1.95, 1.88, 1.62, 1.47, 1. Peaks were observed at 43, 1.36, 1.31, 1.27, and 1.23 ppm.

  Next, 10 g of the obtained polymerization reaction product and 300 mL of methanol were charged into a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, a reflux condenser, and a dropping funnel, and kept at 25 ° C. After removing oxygen in the reaction system through nitrogen gas, 50.4 g (445 mmol) of a 30% hydrogen peroxide solution was added dropwise over 3 hours. Subsequently, after maintaining at 25 ° C. for 8 hours, the reaction solution was filtered, washed with 500 mL of methanol and then with 500 mL of water, and then dried under reduced pressure to obtain 9.6 g of a red powdery methacrylic acid-based crosslinked polymer. .

Example 5
In a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, and a reflux condenser, 79.1 g (311 mmol) of an imino methacrylate compound obtained in the same manner as in Production Example 1, 1,9 -1.0 g (3.1 mmol) of nonanediol dimethacrylate, 1.1 g (3.1 mmol) of methacrylic acid-n-stearyl and 150 mL of tetrahydrofuran were prepared to obtain a homogeneous solution. While maintaining this solution at 25 ° C., oxygen in the reaction system was removed through nitrogen gas, and then 0.358 g (2.2 mmol) of α, α′-azobisisobutyronitrile as a polymerization initiator was added. The solution polymerization reaction was carried out at 50 ° C. for 6 hours under stirring. After completion of the reaction, the reaction solution was cooled to room temperature, added to 2000 mL of hexane, filtered, washed with 500 mL of hexane, and dried under reduced pressure to obtain 80.5 g of a white powder polymerization reaction product (yield) 99.1%).

When the H-NMR (CDCl ₃ ) of the obtained white powder polymerization reaction product was measured, it was 6.23, 3.92, 1.95, 1.88, 1.60, 1.47, 1. Peaks were observed at 43, 1.36, 1.31, 1.27, and 1.23 ppm.

  Next, 18 g of the obtained polymerization reaction product and 150 mL of dichloromethane were charged into a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas introduction tube, a thermometer, a reflux condenser, and a dropping funnel, and kept at 25 ° C. After removing oxygen in the reaction system through nitrogen gas, 34.0 g (pure content 65 wt%, 128 mmol) of m-chloroperbenzoic acid dissolved in 200 mL of dichloromethane was added dropwise over 5 hours. Subsequently, after maintaining at 25 ° C. for 6 hours, the white precipitate was separated and removed from the reaction solution by centrifugation, and the remaining upper layer was washed with 150 mL of 10 wt% aqueous potassium carbonate solution and then with 150 mL of saturated saline solution, respectively. Was dehydrated with an appropriate amount of magnesium sulfate, and magnesium sulfate was removed, followed by drying under reduced pressure to obtain 16.4 g of a red powdery methacrylic acid-based crosslinked polymer.

Evaluation of methacrylic acid-based crosslinked polymer Each solvent of propylene carbonate, diethyl carbonate, and a mixed solvent of ethylene carbonate / diethyl carbonate (weight ratio: 3/7) for the methacrylic acid-based crosslinked polymer obtained in Examples 1 to 5. Was evaluated for solubility. Each powder was mixed with each solvent so that the powder concentration was 10% by weight, stirred for 24 hours at room temperature, and then filtered to obtain a filtrate, which was dried under reduced pressure at 150 ° C. and 10 mmHg for 15 hours. Crude dissolution was obtained. This coarsely dissolved component was washed with pure water and dried under reduced pressure at 150 ° C. and 10 mmHg for 3 hours to obtain a dissolved component, and the solubility was determined. These results are shown in Table 1.

  From the results shown in Table 1, the methacrylic acid-based crosslinked polymers obtained in Examples 1 to 5 are excellent in solvent stability because their solubility in all solvents used for evaluation is less than 1%. You can see that

  The methacrylic acid-based crosslinked polymer obtained in Example 2 was mixed at 10% by weight with respect to each solvent used in the above evaluation, and then stored at 40 ° C. with stirring. After elapse of a predetermined period, the filtrate obtained by filtration was dried under reduced pressure at 150 ° C. and 10 mmHg for 15 hours to obtain a coarsely dissolved component. This coarsely dissolved component was washed with pure water, and dried under reduced pressure at 150 ° C. and 10 mmHg for 3 hours to obtain a dissolved component to determine solubility. The results are shown in Table 2.

  From the results shown in Table 2, the methacrylic acid-based crosslinked polymer obtained in Example 2 has a solubility in all solvents used for evaluation of less than 1% over a storage period of 50 days. It can be seen that the solvent stability is excellent.

Example 6 (Preparation of an electrode for a lithium ion secondary battery)
The methacrylic acid-based crosslinked polymer obtained in Example 2 was pulverized using an agate mortar to a particle size of 100 μm or less, 0.5 g of which was obtained, 10 g of N-methylpyrrolidone as a solvent, and A black slurry was obtained by mixing and stirring 0.1 g of polyvinylidene fluoride and 0.4 g of graphite powder as an auxiliary conductive material. 2 g of this slurry was dropped on the surface of an aluminum foil (area: 1.5 cm × 1.5 cm, thickness: 100 μm) provided with a lead wire, and developed so as to have a uniform thickness with a wire bar. By drying under reduced pressure at 120 ° C. for 6 hours, an electrode in which the methacrylic acid-based crosslinked polymer obtained in Example 2 was bound to a current collector was produced. When the coated surface of the current collector was visually observed, no cracks were observed. In addition, about the coating film which consists of a methacrylic acid type crosslinked polymer, when the film thickness was measured using the micrometer, it was 140 micrometers.

Example 7
An electrode was prepared in the same manner as in Example 6 except that the methacrylic acid-based crosslinked polymer obtained in Example 3 was used instead of the methacrylic acid-based crosslinked polymer obtained in Example 2. No cracks were observed on the surface of the electric conductor. In addition, it was 140 micrometers when the film thickness was measured like Example 6.

Example 8
An electrode was prepared in the same manner as in Example 6 except that the methacrylic acid-based crosslinked polymer obtained in Example 4 was used in place of the methacrylic acid-based crosslinked polymer obtained in Example 2. No cracks were observed on the surface of the electric conductor. In addition, it was 150 micrometers when the film thickness was measured like Example 6. FIG.

Example 9
An electrode was prepared in the same manner as in Example 6 except that the methacrylic acid-based crosslinked polymer obtained in Example 5 was used instead of the methacrylic acid-based crosslinked polymer obtained in Example 2. No cracks were observed on the surface of the electric conductor. In addition, it was 150 micrometers when the film thickness was measured like Example 6. FIG.

Claims (7)

General formula (1):

(In formula (1), R represents a hydrogen atom or a methyl group.) A (meth) acrylic acid imino compound represented by the formula is polymerized in the presence of a crosslinking agent together with a (meth) acrylic acid ester if necessary. Then, a (meth) acrylic acid-based crosslinked polymer obtained by nitroxide formation.   (Meth) acrylic acid ester is hexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate and behenyl (meth) acrylate The (meth) acrylic acid-based crosslinked polymer according to claim 1, which is at least one selected from the group consisting of:   The (meth) acrylic acid-based crosslinking weight according to claim 1 or 2, wherein the (meth) acrylic acid ester is used in a proportion of 0 to 0.25 mol with respect to 1 mol of the (meth) acrylic acid imino compound. Coalescence.   The crosslinking agent is ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,8-octanediol di (meth) acrylate and 1, The (meth) acrylic acid-based crosslinked polymer according to any one of claims 1 to 3, which is at least one selected from the group consisting of 9-nonanediol di (meth) acrylate.   The (meth) acrylic acid-based crosslinked polymer according to any one of claims 1 to 4, wherein the polymerization method is a suspension polymerization method.   The (meth) acrylic acid-based crosslinked polymer according to any one of claims 1 to 4, wherein the polymerization method is an emulsion polymerization method. The electrode of the secondary battery using the (meth) acrylic-acid type crosslinked polymer in any one of Claims 1-6.