JP7121685B2 - Polymer-grafted microparticles, method for producing the same, and solid electrolyte - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polymer-grafted fine particle, a method for producing the same, and a solid electrolyte using the polymer-grafted fine particle.

In recent years, materials such as electrolytes using ionic organic materials such as ionic liquids and lithium salt compounds have been actively investigated. For example, antistatic agents used in electronic devices and displays, permanent antistatic agents not dependent on moisture, and electrolytes used in lithium-ion batteries and all-solid-state batteries are known. Materials such as these electrolytes are required to have high ionic conductivity.

As a related prior art, for example, an electrolyte membrane for a lithium ion battery is proposed in which a graft copolymer having a side chain containing a quaternary ammonium cation is doped with a lithium salt (Patent Document 1). An antistatic agent containing a graft polymer having a block containing an onium salt in its side chain has also been proposed (Patent Document 2). Furthermore, a polymer solid electrolyte has been proposed that contains fine composite particles made of a graft polymer containing a graft chain polymerized by a monomer having a polymerizable functional group (Patent Document 3).

Japanese Patent No. 4640544 WO2009/081591 Japanese Patent No. 5705123

However, when producing the graft polymer or the like proposed in Patent Documents 1 and 2, it is necessary to remove the polymer alone, so the solvent used for the polymerization should be removed, or impurities and remaining raw materials should be removed. I had to refine it. Furthermore, the polymer taken out is soft or easily hygroscopic, so that it is difficult to handle in some cases.

The composite microparticles proposed in Patent Document 3 are obtained by grafting a polymer onto the surface of the microparticles, and are powdery and relatively easy to handle. However, this fine composite particle has a very small amount of polymer single layer having ionic groups (functional groups) attached to the surface of the fine particles, and the amount of ionic groups per unit mass is small.

The present invention has been made in view of the problems of the prior art, and its object is to achieve good compatibility with various media and to reduce the amount of functional groups per unit mass. The object of the present invention is to provide polymer-grafted microparticles which are easy to manufacture and handle. Another object of the present invention is to provide a method for producing the polymer-grafted fine particles and a solid electrolyte using the polymer-grafted fine particles.

That is, according to the present invention, the following polymer-grafted fine particles are provided.
[1] Organic crosslinked microparticles (A) and a linear chain having a constitutional unit derived from a methacrylate-based monomer (b) having a quaternary ammonium base, one end of which is bound to the crosslinked microparticles (A) and a methacrylate-based polymer (B-1), wherein the methacrylate-based polymer (B-1) extends from a polymerization initiation group represented by the following general formula (1) in the crosslinked fine particles (A) It is a graft chain, the mass ratio of the crosslinked fine particles (A) and the methacrylate polymer (B-1) is (A):(B-1)=10 to 90:10 to 90, and the number average particle diameter is 0.1 to 10 μm, and the crosslinked fine particles (A) are methacrylate-based polymers having structural units derived from the methacrylate-based monomer (a) having a polymerization initiation group represented by the general formula (1). The crosslinked microparticles formed in (A), wherein the counter anions of said quaternary ammonium base are bis(trifluoromethylsulfonyl)imide anion, bis(fluorosulfonyl)imide anion, tetrafluoroborate anion, and trifluoro Polymer-grafted microparticles containing at least one of (trifluoromethyl)borate anions .

（前記一般式（１）中、Ｒ_１は、水素原子、アルキル基、又はアシル基を示し、Ｒ_２は、アルキル基又はアリール基を示し、Ｘは、塩素原子、臭素原子、又はヨウ素原子を示し、Ｙは、Ｏ又はＮＨを示し、＊は、前記メタクリレート系モノマー（ａ）における結合部位を示す）

(In the general formula (1), R ₁ represents a hydrogen atom, an alkyl group, or an acyl group, R ₂ represents an alkyl group or an aryl group, and X represents a chlorine atom, a bromine atom, or an iodine atom. Y represents O or NH , * represents a binding site in the methacrylate-based monomer (a) )

[2 ] further comprising a methacrylate-based polymer (B-2) having no structural unit derived from the methacrylate-based monomer (b), one end of which is bound to the crosslinked fine particles (A), wherein the methacrylate-based polymer (B -2) is a graft chain extended from a polymerization initiation group represented by the following general formula (1) in the crosslinked fine particles (A), the crosslinked fine particles (A), the methacrylate polymer (B-1) , and the mass ratio of the methacrylate polymer (B-2) is (A): (B-1): (B-2) = 10 to 90: 5 to 85: 5 to 85 [ 1 ] Polymer-grafted microparticles as described.
[ 3 ] The polymer-grafted microparticles according to [1] or [2] , wherein in general formula (1), _R1 is a methyl group, _R2 is a methyl group, and X is a bromine atom.
[ 4 ] The polymer-grafted microparticles according to any one of [1] to [ 3 ], wherein the counter anion of the quaternary ammonium base is a bis(trifluoromethylsulfonyl)imide anion.

Further, according to the present invention, there is provided the following method for producing polymer-grafted fine particles.
[6] The method for producing polymer-grafted fine particles according to any one of [1] to [ 4 ], wherein in the presence of the crosslinked fine particles (A) and a quaternary halogenated ammonium salt as a catalyst, dimethylamino A polymer having a step of polymerizing a monomer containing at least one of ethyl methacrylate and diethylaminoethyl methacrylate and then reacting it with an alkyl halide to form the methacrylate-based polymer (B-1) having a quaternary ammonium group. A method for producing graft microparticles.

（前記一般式（１）中、Ｒ_１は、水素原子、アルキル基、又はアシル基を示し、Ｒ_２は、アルキル基又はアリール基を示し、Ｘは、塩素原子、臭素原子、又はヨウ素原子を示し、Ｙは、Ｏ又はＮＨを示し、＊は、前記メタクリレート系モノマー（ａ）における結合部位を示す）
［８］前記リチウム塩が、テトラフルオロホウ酸リチウム、ヘキサフルオロリン酸リチウム、トリフルオロメタンスルホン酸リチウム、ビス（フロロスルホニル）イミドリチウム、ビス（トリフルオロメタンスルホニル）イミドリチウム、及び（フルオロスルホニル）－（トリフルオロメタンスルホニル）イミドリチウムからなる群より選択される少なくとも一種である前記［６］又は［７］に記載の固体電解質。 Furthermore, according to the present invention, the following solid electrolyte is provided.
[6] A solid electrolyte comprising the polymer-grafted fine particles according to any one of [1] to [4] and a lithium salt.
[7] A quaternary ammonium base containing a polymer-grafted fine particle and a lithium salt, wherein the polymer-grafted fine particle is an organic crosslinked fine particle (A) and one end thereof is bound to the crosslinked fine particle (A). a linear methacrylate-based polymer (B-1) having structural units derived from the methacrylate-based monomer (b) having the is a graft chain extended from a polymerization initiation group represented by the following general formula (1), and the mass ratio of the crosslinked fine particles (A) and the methacrylate polymer (B-1) is (A):(B -1) = 10 to 90: 10 to 90, the number average particle diameter is 0.1 to 10 µm, and the crosslinked fine particles (A) have a polymerization initiating group represented by the general formula (1) A solid electrolyte that is crosslinked fine particles formed of a methacrylate-based polymer (A) having structural units derived from a methacrylate-based monomer (a).

(In the general formula (1), R ₁ represents a hydrogen atom, an alkyl group, or an acyl group, R ₂ represents an alkyl group or an aryl group, and X represents a chlorine atom, a bromine atom, or an iodine atom. Y represents O or NH , * represents a binding site in the methacrylate-based monomer (a) )
[8] The lithium salt is lithium tetrafluoroborate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and (fluorosulfonyl)-( The solid electrolyte according to the above [6] or [7], which is at least one selected from the group consisting of lithium trifluoromethanesulfonyl)imide.

According to the present invention, it is possible to provide polymer-grafted fine particles that have a large amount of functional groups per unit mass and are easy to manufacture and handle. Further, according to the present invention, it is possible to provide a method for producing the polymer-grafted fine particles and a solid electrolyte using the polymer-grafted fine particles.

Since the polymer-grafted microparticles of the present invention have a large amount of functional groups per unit mass, sufficient ionic conductivity can be obtained even when the amount used is reduced compared to conventional ones, and a large amount can be used. , a higher conductivity can be obtained. In addition, since the polymer-grafted microparticles of the present invention are microparticles, they can be produced by a simple process, and can contribute to reduction of the production process and production cost as well as reduction of environmental load. Furthermore, the polymer-grafted fine particles of the present invention can be freely designed in terms of compatibility with various media, and can be easily dispersed or homogenized in various media.

<Polymer graft fine particles>
Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments. The polymer-grafted microparticles of the present invention are derived from organic or inorganic crosslinked microparticles (A) and a methacrylate-based monomer (b) having a quaternary ammonium base, one end of which is bound to the crosslinked microparticles (A). and a linear methacrylate-based polymer (B-1) having a structural unit. The methacrylate-based polymer (B-1) is a graft chain extended from the polymerization initiation group represented by the following general formula (1) in the crosslinked fine particles (A). In the polymer-grafted fine particles of the present invention, the mass ratio of the crosslinked fine particles (A) and the methacrylate-based polymer (B-1) is (A):(B-1)=10-90:10-90. The average particle size is 0.01-10 μm. That is, the polymer-grafted microparticles of the present invention include crosslinked microparticles (A) and a methacrylate-based polymer (B-1) having one end bound (grafted) to crosslinked microparticles (A).

（前記一般式（１）中、Ｒ_１は、水素原子、アルキル基、又はアシル基を示し、Ｒ_２は、アルキル基又はアリール基を示し、Ｘは、塩素原子、臭素原子、又はヨウ素原子を示し、Ｙは、Ｏ又はＮＨを示し、＊は、前記メタクリレート系モノマー（ａ）における結合部位を示す）

(In the general formula (1), R ₁ represents a hydrogen atom, an alkyl group, or an acyl group, R ₂ represents an alkyl group or an aryl group, and X represents a chlorine atom, a bromine atom, or an iodine atom. Y represents O or NH , * represents a binding site in the methacrylate-based monomer (a) )

(Crosslinked microparticles (A))
The crosslinked fine particles (A) are organic crosslinked fine particles or inorganic crosslinked fine particles having a three-dimensional network structure inside. Examples of organic crosslinked microparticles include conventionally known polymer microparticles such as crosslinked polyacrylic microparticles, polymethacrylic microparticles, polystyrene microparticles, polyolefin microparticles, polyurethane microparticles, and polyamide microparticles. Examples of inorganic crosslinked fine particles include inorganic fillers such as silica fine particles and titanium oxide fine particles; and fine particles such as inorganic pigments. Among them, the crosslinked fine particle (A) is an organic polymer formed of a methacrylate-based polymer (A) having a structural unit derived from a methacrylate-based monomer (a) having a polymerization initiation group represented by the general formula (1). are preferably crosslinked fine particles. In addition, organic or inorganic crosslinked fine particles are reacted with a silane coupling agent having a group represented by general formula (1) and an alkoxysilyl group, and a surface of the crosslinked fine particles represented by general formula (1) is reacted. Those having groups introduced can also be used as the crosslinked fine particles (A).

The group represented by the general formula (1) is a group that functions as a polymerization initiation group for vinyl monomers. When a polymer having a group represented by general formula (1) and a vinyl-based monomer are mixed and heated, polymerization of the vinyl-based monomer starts from the group represented by general formula (1) to form a polymer. do. In general formula (1), a chlorine atom, a bromine atom, or an iodine atom represented by X is a group that can be eliminated or substituted as a radical.

Specifically, the group represented by the general formula (1) is a carboxylic acid ester or amide group represented by the following general formula (3). Examples of such carboxylic acid esters or amides include conventionally known compounds.

（前記一般式（３）中、Ｒ_１は、水素原子、アルキル基、又はアシル基を示し、Ｒ_２は、アルキル基又はアリール基を示し、Ｘは、塩素原子、臭素原子、又はヨウ素原子を示す）

(In the general formula (3), R ₁ represents a hydrogen atom, an alkyl group, or an acyl group, R ₂ represents an alkyl group or an aryl group, and X represents a chlorine atom, a bromine atom, or an iodine atom. show)

In general formula (1), it is preferred that R ₁ is a methyl group, R ₂ is a methyl group, and X is a bromine atom. That is, the polymerization initiation group represented by the general formula (1) is a group represented by the following general formula (2). It is preferable because it is possible. The group represented by general formula (2) is derived, for example, from an ester or amide of 2-bromoisobutanoic acid.

（前記一般式（２）中、Ｙは、Ｏ又はＮＨを示し、＊は、前記メタクリレート系モノマー（ａ）における結合部位を示す）

(In the general formula (2), Y represents O or NH , * represents a binding site in the methacrylate-based monomer (a) )

A monomer having a group represented by formula (1) and a silane coupling agent can be obtained according to a conventionally known method. For example, it can be obtained by reacting a carboxylic acid, a carboxylic acid anhydride, or a carboxylic acid halide having a group represented by the general formula (1) with a compound having a hydroxyl group or an amino group. It can also be obtained by reacting a carboxylic acid or the like having a group represented by general formula (1) with a compound having an epoxy group.

When the above-described methacrylate-based polymer (A) is used as the polymer that forms the crosslinked fine particles (A), various monomers can be used, and the refractive index, glass transition point, and soft/hardness of the polymer obtained by the monomer used can be adjusted. It is preferable because the physical properties such as the properties can be adjusted. Furthermore, it is preferable because the particle size of the resulting crosslinked fine particles (A) can be easily controlled.

Crosslinked fine particles (A) can be produced according to a conventionally known method. For example, using a methacrylate-based monomer (a) having a polymerization initiation group represented by the general formula (1) and a difunctional or higher methacrylate-based monomer, and further using another copolymerizable monomer, emulsification Polymerize, suspension polymerize, or precipitate polymerize. Thereby, crosslinked fine particles (A) having a polymerization initiation group represented by the general formula (1) can be obtained. Alternatively, after obtaining fine particles by polymerizing a methacrylate-based monomer having a functional group such as a hydroxyl group, an epoxy group, or an isocyanate group, a carboxylic acid having a polymerization initiation group represented by general formula (1) or a derivative thereof is reacted. This also makes it possible to obtain crosslinked fine particles (A) having a polymerization initiation group represented by general formula (1).

As the methacrylate-based monomer (a) having a polymerization initiation group represented by general formula (1), an ester or amide of 2-bromoisobutanoic acid can be used. Preferred examples of the methacrylate monomer (a) include 2-(2-bromoisobutyryloxy)ethyl methacrylate, 3-(2-bromoisobutyryloxy)propyl methacrylate, 2-(2-bromoisobutyryloxy ) propyl methacrylate, 4-(2-bromoisobutyryloxy) butyl methacrylate, 2-hydroxy-3-(2-bromoisobutyryloxy) propyl methacrylate, 2-chloro-3-(2-bromoisobutyryloxy ) propyl methacrylate, methacryloyloxyethyl-N-(2-bromoisobutyryloxy)amine, and the like.

Bifunctional or higher methacrylate monomers include (poly)ethylene glycol dimethacrylate, (poly)propylene glycol dimethacrylate, (poly)butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, Methacrylate, (poly)ethylene glycol adduct dimethacrylate of bisphenol A, polyurethane dimethacrylate, polyester dimethacrylate, polyolefin dimethacrylate, vinyl methacrylate, and allyl methacrylate.

Tri- or higher functional methacrylate monomers include glyceryl trimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, tripentaerythritol hexamethacrylate, polypentaerythritol hexamethacrylate, polymer polyol methacrylate, and the like. be able to.

Furthermore, monofunctional methacrylate-based monomers may be used. Monofunctional methacrylate-based monomers include carboxy group-containing methacrylic acid-based monomers such as methacrylic acid and 2-methacryloyloxyethyl phthalate; Alkyl and alkenyl methacrylates such as methacrylate, lauryl methacrylate, tricyclodecyl methacrylate, stearyl methacrylate, isostearyl methacrylate, allyl methacrylate; cyclohexyl methacrylate, t-butylcyclohexyl methacrylate, trimethylcyclohexyl methacrylate, isobornyl methacrylate, dicyclopentanyl methacrylate , cycloalkyl methacrylates and cycloalkenyl methacrylates such as dicyclopentenyl methacrylate; methacrylates having aromatic rings such as benzyl methacrylate and phenyl methacrylate; phenoxyethyl methacrylate, dicyclopentenyloxyethyl methacrylate, 2-hydroxyethyl methacrylate, tetrahydrofurfuryl methacrylate, oxygen atom-containing methacrylates such as glycidyl methacrylate; basic methacrylates such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and t-butylaminoethyl methacrylate; halogen-containing methacrylates such as trifluoroethyl methacrylate and heptadecafluorodecyl methacrylate; Silicon atom-containing methacrylates such as siloxane methacrylate; UV absorbing groups such as 2-(4-benzoxy-3-hydroxyphenoxy)ethyl methacrylate, 2-(2'-hydroxy-5-methacryloyloxyethylphenyl)-2H-benzotriazole nitrogen atom-containing methacrylates such as tetramethylpiperidinyl methacrylate and diethylaminoethyl methacrylate. Furthermore, if necessary, a macromonomer having a methacryloyl group at one end thereof can also be used.

In the methacrylate-based polymer (A) constituting the crosslinked fine particles (A), the content of structural units derived from the methacrylate-based monomer (a) having a polymerization initiation group represented by general formula (1) is 0.1. It is preferably at least 1% by mass, more preferably at least 1% by mass, and particularly preferably at least 10% by mass. The upper limit of the content of structural units derived from the methacrylate-based monomer (a) in the methacrylate-based polymer (A) is not particularly limited, but may be 100% by mass. If the content of structural units derived from the methacrylate-based monomer (a) in the methacrylate-based polymer (A) is less than 0.1% by mass, the introduction amount of the methacrylate-based polymer (B-1) as a graft chain is excessive. may be less.

In the methacrylate-based polymer (A), the content of structural units derived from bifunctional or higher-functional methacrylate-based monomers is preferably 1% by mass or more, more preferably 5% by mass or more. In the methacrylate-based polymer (A), if the content of structural units derived from a bifunctional or higher-functional methacrylate-based monomer is less than 1% by mass, the strength of the crosslinked fine particles may become weak. For this reason, a component that dissolves in the solvent may occur, or the crosslinked fine particles (A) may swell excessively.

The number average particle size of the crosslinked fine particles (A) is smaller than the number average particle size of the polymer-grafted fine particles containing the crosslinked fine particles (A). That is, the number average particle size of the crosslinked fine particles (A) is preferably smaller than the number average particle size of the polymer-grafted fine particles within the range of 0.01 to 10 μm, and the number average particle size of the polymer-grafted fine particles is within the range of 0.1 to 10 μm. is more preferably smaller than the number average particle size of In addition, the "number average particle size" in this specification means the number average particle size measured and calculated by the light scattering method.

(Methacrylate-based polymer (B-1))
The methacrylate-based polymer (B-1) is a graft chain extended from the polymerization initiation group represented by general formula (1) in the crosslinked fine particles (A). One end of this methacrylate polymer (B-1) is bound to the crosslinked microparticles (A). The methacrylate-based polymer (B-1) is a linear polymer having structural units derived from the methacrylate-based monomer (b) having a quaternary ammonium base. The grafted chain having this quaternary ammonium base has ionicity, so it functions as an electrolyte and exhibits ionic conductivity and electrical conductivity.

The quaternary ammonium base includes quaternary ammonium base derived from dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; quaternary ammonium formed by reacting 3-chloro-2-hydroxypropyl methacrylate with a tertiary amine. bases; betaine-type quaternary ammonium bases such as 3-[[2-(methacryloyloxy)ethyl]dimethylammonio]propionate and 2-methacryloyloxyethylphosphorylcholine; Among them, quaternary ammonium bases derived from dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate are preferable because they are easy to synthesize and can introduce various kinds of counter anions.

Quaternary ammonium salts include chloride salts, bromide salts, iodide salts, triiodide salts, methanesulfonates, toluenesulfonates, trifluoromethanesulfonates, bis(trifluoromethanesulfonyl)imide salts, bis(fluorosulfonyl) Imide salts, tetrafluoroboron salts, trifluoro(trifluoromethyl)boron salts, hexafluorophosphate salts, thiocyanate salts, dicyanamide salts and the like can be mentioned. Of these, bis(trifluoromethanesulfonyl)imide salts are preferred because they are highly hydrophobic and have a high affinity with organic solvents. That is, the counter anion of the quaternary ammonium base is preferably bis(trifluoromethylsulfonyl)imide anion.

In the methacrylate-based polymer (B-1), which is a graft chain, the content of structural units derived from the methacrylate-based monomer (b) having a quaternary ammonium base is preferably 10% by mass or more, and 50% by mass. % or more is more preferable. The methacrylate-based polymer (B-1) may have structural units (other structural units) other than the structural units derived from the methacrylate-based monomer (b). Examples of monomers constituting other structural units include the above-mentioned monofunctional methacrylate-based monomers.

(Polymer graft microparticles)
The mass ratio of the crosslinked fine particles (A) and the methacrylate polymer (B-1), which constitute the polymer graft fine particles, is (A):(B-1)=10 to 90:10 to 90, preferably (A ):(B-1)=20-80:20-80, more preferably (A):(B-1)=30-70:30-70. If the mass ratio of the crosslinked fine particles (A) is too low, the properties of the particles are likely to be impaired, and inconveniences such as difficulty in filtration during production are likely to occur. On the other hand, if the mass ratio of the crosslinked fine particles (A) is too high, the amount of the quaternary ammonium salt is relatively decreased, so that the function as an electrolyte may not be exhibited.

The polymer-grafted microparticles preferably further contain a methacrylate-based polymer (B-2) having no structural unit derived from the methacrylate-based monomer (b) and having one end bonded to the crosslinked microparticles (A). The methacrylate polymer (B-2), like the methacrylate polymer (B-1), is a graft chain extended from the polymerization initiation group represented by general formula (1) in the crosslinked fine particles (A). By grafting the methacrylate-based polymer (B-2) to the crosslinked fine particles (A), it is possible to improve the affinity for the dispersion medium in which the polymer-grafted fine particles are dispersed and to improve the ionic conductivity. Examples of the monomer constituting the methacrylate-based polymer (B-2) include the monofunctional methacrylate-based monomers described above.

When the polymer-grafted fine particles further contain a methacrylate-based polymer (B-2), the mass ratio of the crosslinked fine particles (A), the methacrylate-based polymer (B-1), and the methacrylate-based polymer (B-2) is (A). :(B-1):(B-2)=10-90:5-85:5-85. Further, the mass ratio of (A):(B-1):(B-2) is more preferably 10 to 80:10 to 80:10 to 80, and (A):(B-1 ):(B-2)=10-60:20-70:20-70 is particularly preferred. If the mass ratio of the methacrylate-based polymer (B-1) is too small, the amount of the quaternary ammonium base is too small, and the function as an electrolyte may be slightly insufficient. On the other hand, if the mass ratio of the methacrylate-based polymer (B-1) is too large, the amount of the crosslinked fine particles (A) is relatively decreased, so the properties of the particles are likely to be impaired, making it difficult to filter during production. inconvenience is likely to occur.

The polystyrene-equivalent number average molecular weights of the methacrylate-based polymer (B-1) and the methacrylate-based polymer (B-2) measured by gel permeation chromatography (GPC) are each 1,000 to 10,000,000. and more preferably 10,000 to 1,000,000. The molecular weight of the polymer to be grafted may be appropriately set according to the use and physical properties of the polymer-grafted particles.

The polymer-grafted microparticles of the present invention have a larger amount of functional groups per unit mass than conventional polymer microparticles having functional groups such as ionic groups. Specifically, the amount (mmol/g) of the quaternary ammonium base per unit mass of the polymer-grafted fine particles of the present invention is preferably 0.1 mmol/g or more, more preferably 0.5 mmol/g or more, and particularly preferably is 1.0 mmol/g or more, most preferably 1.5 mmol/g or more.

The polymer-grafted fine particles of the present invention can be used, for example, as antistatic agents, conductive materials, and electrolytes for battery materials. Furthermore, the polymer-grafted fine particles of the present invention are materials that can exhibit various properties such as ionic conductivity and proton conductivity, and are expected to be applied to fields that take advantage of these properties.

<Method for producing polymer-grafted fine particles>
The polymer-grafted microparticles described above can be produced by the method described below. That is, in the method for producing polymer-grafted fine particles of the present invention, a monomer containing at least one of dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate is polymerized in the presence of the crosslinked fine particles (A) and a halogenated quaternary ammonium salt as a catalyst. After that, there is a step of reacting an alkyl halide to form a methacrylate-based polymer (B-1) having a quaternary ammonium group. Specifically, crosslinked fine particles (A) having a polymerization initiation group represented by the general formula (1) are prepared, and a methacrylate-based monomer (b) having a quaternary ammonium base is polymerized starting from the polymerization initiation group. , the methacrylate-based polymer (B-1), which is a graft chain, is preferably extended.

The polymer-grafted fine particles can also be produced by methods other than the above method. For example, a methacrylate-based polymer (B-1) having a predetermined functional group introduced at its terminal and a crosslinked fine particle (A) having a group capable of reacting with the predetermined functional group introduced are prepared. Polymer-grafted microparticles can also be produced by reacting a predetermined functional group of the prepared methacrylate-based polymer (B-1) with a group capable of reacting with a predetermined functional group of the crosslinked microparticles (A). can.

A polymerization reaction initiated from the polymerization initiating group represented by formula (1) can be carried out according to a conventionally known method. Examples thereof include atom transfer radical polymerization in which oxidation-reduction of a metal complex such as copper is used for polymerization, reversible transfer catalyst polymerization using an organic catalyst, and reversible catalyst-mediated polymerization. Among them, crosslinked fine particles (A) having a polymerization initiation group represented by general formula (1), a halogen exchange agent, and a quaternary ammonium halide salt (preferably, a quaternary ammonium iodide salt) as a catalyst A method of polymerizing a monomer containing at least one of dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate in the presence of is preferred. Details of this method are described in JP-A-2018-90711.

As a method for introducing a quaternary ammonium base into the methacrylate-based polymer (B-1), for example, starting from the polymerization initiation group represented by general formula (1) in the crosslinked fine particles (A), (i) A method of polymerizing a methacrylate monomer having a quaternary ammonium base; (ii) a method of polymerizing an amino group-containing methacrylate monomer and then quaternizing the amino group; However, a methacrylate-based monomer having a quaternary ammonium base may be difficult to dissolve in a low-polar solvent or a monomer to be copolymerized. Therefore, a monomer containing at least one of dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate is polymerized in the presence of the crosslinked fine particles (A) and a halogenated quaternary ammonium salt as a catalyst, and then the alkyl halide is reacted. , to form a methacrylate-based polymer (B-1) having a quaternary ammonium base. Examples of alkyl halides that can be used include methyl chloride, methyl iodide, and benzyl chloride.

The counter anion that constitutes the quaternary ammonium base formed by reacting the amino group with the alkyl halide can be exchanged for the desired anion. For example, the amino group is reacted with benzyl chloride to form a quaternary ammonium base, followed by the addition of a salt such as sodium tetrafluoroborate, lithium bis(trifluoromethanesulfonyl)imide, etc., resulting in anion exchange and the desired It can be a quaternary ammonium salt containing a counter anion such as

Further, when producing polymer-grafted fine particles further comprising a methacrylate-based polymer (B-2) having no structural unit derived from a methacrylate-based monomer (b), one end of which is bound to the crosslinked fine particles (A), For example, the contents described in JP-A-2018-178028 can be taken into consideration. Above all, it is preferable to form the methacrylate polymer (B-2) having no quaternary ammonium base and then form the methacrylate polymer (B-1) having a quaternary ammonium base.

After polymerizing a monomer containing at least one of dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate in an organic solvent in the presence of crosslinked fine particles (A), the product is filtered or added to a poor solvent to filter precipitates, Then, by washing and drying, a precursor of polymer-grafted fine particles can be obtained. As the organic solvent, it is preferable to use an organic solvent capable of dissolving the quaternary ammonium salt. Examples of such organic solvents include polar solvents such as lower alcohols, glycols, amide solvents, urea solvents, and sulfoxide solvents.

Further, when the polymerization is carried out in the above organic solvent, the quaternary ammonium base is added to the polymerization system without isolating the product (precursor of the polymer-grafted fine particles) after the polymerization. can be formed. After that, by diluting with water and adding an alkali metal salt containing the desired anion to exchange the anion, polymer-grafted fine particles containing the desired counter anion can be obtained. As the alkali metal salt, bis(trifluoromethanesulfonyl)imidelithium is preferred. When lithium bis(trifluoromethanesulfonyl)imide is used for ion exchange, the formed polymer-grafted microparticles having a quaternary ammonium base become insoluble in water and tend to precipitate, thus facilitating purification.

<Solid electrolyte>
The polymer-grafted microparticles described above can be used as a solid electrolyte. In order to further exhibit the function as a solid electrolyte, it is also preferable to use polymer-graft fine particles doped with lithium as the solid electrolyte. That is, the solid electrolyte of the present invention is suitable as a solid electrolyte for an all-solid battery, containing the polymer-grafted fine particles described above and a lithium salt.

Lithium salts include lithium tetrafluoroborate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and (fluorosulfonyl)-(trifluoromethanesulfonyl ) imidelithium and the like.

A solid electrolyte can be obtained by mixing polymer-grafted fine particles and a lithium salt. The mixing ratio of the polymer-grafted fine particles and the lithium salt can be appropriately set according to the amount of the quaternary ammonium base in the polymer-grafted fine particles. Specifically, the amount of the lithium salt is preferably 5 to 100 parts by mass, more preferably 10 to 50 parts by mass, based on 100 parts by mass of the polymer-grafted fine particles.

Both the polymer-grafted fine particles and the mixture of the polymer-grafted fine particles and the lithium salt can be used as they are as the solid electrolyte. Further, by dispersing it in a medium such as an ionic liquid or ethylene carbonate, it can be used as a material for a lithium ion battery. Furthermore, by mixing with a plastic material, it can exhibit functions as an antistatic agent and an antifog agent. When used by being added to a plastic material, the amount of addition of the polymer-grafted fine particles or the mixture of the polymer-grafted fine particles and the lithium salt is preferably 10% by mass or less relative to the plastic material. When the polymer-grafted fine particles further contain a methacrylate-based polymer (B-2) which is a graft chain, and the methacrylate-based polymer (B-2) has an affinity for the dispersion medium, the polymer-grafted fine particles can be well dispersed in the dispersion medium.

EXAMPLES The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples. "Parts" and "%" in Examples and Comparative Examples are based on mass unless otherwise specified.

<Production of crosslinked fine particles (A)>
(Production Example 1: Crosslinked microparticles (A)-1)
600 parts of ethyl acetate, 150 parts of diethylene glycol dimethacrylate (DEGDMA), and 50 parts of 2-(2-bromoisobutyryloxy)ethyl methacrylate (BEMA) were placed in a reaction vessel and immersed in a hot water bath at 70°C. I warmed up. 20 parts of ethyl acetate and 2.2 parts of azobisisobutyronitrile (AIBN) were placed in a separate container, and AIBN was dissolved to prepare an initiator solution. When the temperature inside the reaction vessel (inside the reaction system) reached 65°C, the initiator solution was added. When the reaction was carried out at 65° C. for 10 hours, the reaction system became cloudy and the particles aggregated and precipitated. After cooling, the reaction system was filtered and washed with ethyl acetate. It was dried at 70° C. using a blower dryer to obtain 186 parts of white powder. The content of structural units derived from BEMA calculated by measuring solid NMR was 21.8%. The resulting white powder was observed under a microscope and confirmed to be spherical fine particles. After dispersing the white powder obtained using ultrasonic waves in ion-exchanged water, the number average particle diameter measured using a Coulter counter (manufactured by Beckman Coulter, Inc.) was 1.89 μm. The resulting white powder was pulverized with a pulverizer and passed through 100 mesh to obtain crosslinked fine particles (A)-1.

(Production Example 2: Crosslinked microparticles (A)-2)
Crosslinked fine particles (A)-2 were obtained in the same manner as in Production Example 1 described above, except that the reaction time was 5 hours. The content of structural units derived from BEMA was 16.0%, and the number average particle diameter was 890 nm.

(Production Example 3: Crosslinked microparticles (A)-3)
Crosslinked fine particles (A)-3 were obtained in the same manner as in Production Example 1 described above, except that the amount of DEGDMA was changed to 85 parts and the amount of EBMA was changed to 15 parts. The content of structural units derived from BEMA was 13.6%, and the number average particle size was 1.69 µm.

(Comparative production example: Comparative crosslinked fine particles (A))
150 parts of ethanol, 10 parts of 25% aqueous ammonia, 1 part of 2-bromo-2-methylpropionyloxypropyltrimethoxysilane, and 100 parts of silica spherical fine particles (number average particle size: 1.5 μm) are placed in a flask and stirred for 24 hours. did. The precipitate formed by pouring into water was filtered and washed with water. After drying at 100° C. for 12 hours, it was pulverized to obtain comparative crosslinked fine particles (A). The obtained comparative crosslinked fine particles (A) had a number average particle diameter of 1.5 μm. This comparative crosslinked fine particle is a crosslinked fine particle in which a polymerization initiation group is bonded to the surface of a silica spherical fine particle.

<Production of polymer-grafted microparticles>
( Reference Example 1: Polymer graft fine particles -1)
In a reaction vessel, 100 parts of 3-methoxy-N,N-dimethylpropionamide (MDPA), 10 parts of crosslinked fine particles (A)-1 obtained in Production Example 1, 90 parts of diethylaminoethyl methacrylate (DEAEMA), and tetrabutylammonium 5 parts of iodide (TBAI) was added and stirred at 85° C. for 7 hours. The system (polymerization solution) was slightly thickened by stirring. The polymerization solution was poured into a water/methanol mixed solvent (1/1 (v/v)), and the resulting precipitate was filtered. After thorough washing with a mixed solvent, 40.3 parts of fine particles were obtained. The fine particles obtained had a number average particle diameter of 3.2 μm. It is calculated that 30.3 parts of the polymer of DEAEMA is bonded to the crosslinked fine particles (A)-1. The amine value was 227.2 mgKOH/g. When the obtained microparticles were pulverized and added to water, the microparticles did not get wet and floated on the surface. Then, when 10% hydrochloric acid was added, it was compatible with water and easily dispersed. It is believed that the polymer of DEAEMA, which is water-insoluble, was neutralized with hydrochloric acid and became compatible with water. The obtained microparticles are referred to as PDEAEMA crosslinked microparticles (A)-1. Incidentally, the amine value was obtained by diluting about 0.5 part of the sample with 20 parts of a toluene/ethanol mixed solvent (3/2 (v/v)) and homogenizing it, then using bromophenol blue as an indicator and measuring 0.1 N hydrochloric acid. Ethanol solution was used as the titration solution for titration, measurement and calculation.

10 parts of PDEAEMA crosslinked fine particles (A)-1 were added to 100 parts of methanol and stirred. A mixed solution of 5.7 parts of methyl iodide and 17.2 parts of methanol was added dropwise over 1 hour, followed by stirring at 50° C. for 1 hour. After cooling, it was filtered, washed, and dried at 30° C. using a blower dryer to obtain 15.4 parts of polymer-grafted fine particles-1. When the resulting polymer-grafted fine particles-1 were added to water, they readily dispersed. The amount of the quaternary ammonium base (functional group) per unit mass (1 g) of the polymer-grafted fine particles-1 converted from the amine value of the PDEAEMA crosslinked fine particles (A)-1 was 2.5 mmol. The number average particle diameter of the polymer-grafted fine particles-1 was 4.6 μm. The mass ratio of the crosslinked fine particles (A) and the grafted polymer (B-1) was (A):(B-1)=16.1:83.9.

(Example 2: Polymer graft microparticles-2)
When 10 parts of the polymer-grafted microparticles-1 obtained in Reference Example 1 were added to 100 parts of water and stirred, they were easily dispersed. Then, when a mixture of 7.4 parts of bis(trifluoromethanesulfonyl)imidelithium and 30 parts of water was added dropwise, the system became cloudy and a precipitate was formed. Presumably, the precipitate was formed due to the high hydrophobicity of the quaternary ammonium base having a bis(trifluoromethanesulfonyl)imide anion as a counter anion produced by the salt exchange. After stirring at 60° C. for 1 hour, the mixture was cooled, filtered and washed with water to obtain 13.6 parts of polymer-grafted fine particles-2. The number average particle diameter measured by dispersing the resulting polymer-grafted fine particles-2 in water was 3.4 μm. It is considered that the polymer having a quaternary ammonium base is insoluble in water, so that it shrinks and becomes smaller than the polymer-grafted fine particle-1. The amount of functional groups in polymer-grafted fine particles-2 converted from the amount of functional groups in polymer-grafted fine particles-1 was 1.8 mmol/g. The mass ratio of the crosslinked fine particles (A) and the grafted polymer (B-1) was (A):(B-1)=11.8:88.2.

The resulting polymer-grafted fine particles-2 were added to water and methanol, respectively, but were not dispersed in either. On the other hand, when it was added to tetrahydrofuran (THF) and methyl ethyl ketone (MEK), it dispersed easily in both. The number average particle size of the polymer-graft fine particles-2 dispersed in THF and MEK was 4.8 μm. It is believed that the grafted polymer (B-1) swelled with the solvent and the particle size increased.

( Reference Examples 3 , 5, Examples 4, 6: Polymer graft fine particles-3 to 6)
Polymer-grafted fine particles-3 were obtained in the same manner as in Reference Example 1, except that crosslinked fine particles (A)-2 were used instead of crosslinked fine particles (A)-1. Polymer-grafted fine particles-4 were obtained in the same manner as in Example 2 except that polymer-grafted fine particles-3 were used instead of polymer-grafted fine particles-1.

Furthermore, the same as Reference Example 1 described above except that crosslinked fine particles (A)-3 were used instead of crosslinked fine particles (A)-1 and dimethylaminoethyl methacrylate (DMAEMA) was used instead of DEAEMA. Then, polymer-grafted fine particles-5 were obtained. Polymer-grafted fine particles-6 were obtained in the same manner as in Example 2 except that polymer-grafted fine particles-5 were used instead of polymer-grafted fine particles-1.

Table 1 shows the details of each polymer-grafted fine particle obtained.

It was possible to appropriately change the particle size and the amount of functional groups of the obtained polymer-grafted fine particles, and it was possible to easily design fine particles expected to be used as an electrolyte. In addition, operations such as filtration and washing were easy in all manufacturing steps. That is, the polymer-grafted fine particles of the present embodiment can be produced while removing impurities as much as possible.

(Comparative example: comparative polymer-grafted fine particles)
DEAEMA was added to the comparative crosslinked fine particles (A) in the same manner as in Reference Example 1 described above, except that 10 parts of the comparative crosslinked fine particles (A) obtained in Comparative Production Example were used instead of the crosslinked fine particles (A)-1. 10.3 parts of comparative PDEAEMA crosslinked microparticles (A) to which the polymer of (A) was bound.
The obtained comparative PDEAEMA crosslinked fine particles (A) had an amine value of 8.9 mmgKOH/g and a number average particle size of 1.5 μm. It can be estimated that 0.3 part of the polymer of DEAEMA (PDEAEMA) was introduced with respect to 10 parts of the comparative crosslinked fine particles (A). It is considered that the PDEAEMA simply extends from a small amount of functional groups present on the surface layer of the comparative crosslinked fine particles (A). Although the comparative PDEAEMA crosslinked microparticles (A) were added to water, they were not compatible with water. On the other hand, when 10% hydrochloric acid was added, it dispersed with affinity to water.

Further , bis (trifluoromethanesulfonyl) Comparative polymer-grafted microparticles were obtained in which a polymer having a quaternary ammonium base with an imide anion as a counter anion was grafted. The functional group content of the comparative polymer-grafted fine particles was 0.151 mmol/g. The number average particle size of the comparative polymer-grafted fine particles was 1.5 μm. The mass ratio of the comparative crosslinked fine particles (A) and the grafted polymer (B-1) was (A):(B-1)=3:97.

In Reference Examples 1 , 3 and 5, and Examples 2, 4 and 6, functional groups could be introduced in an amount about 10 times or more as compared to Comparative Examples. That is, the polymer-grafted fine particles of the present embodiment produced in Reference Examples 1 , 3, 5, and Examples 2, 4, and 6 contain a large amount of the ionizable quaternary ammonium base, and thus can be used as good electrolytes. There is expected.

( Reference Example 7: Polymer graft fine particles -7)
100 parts of MDPA, 30 parts of crosslinked fine particles (A)-1 obtained in Production Example 1, 30 parts of methyl methacrylate (MMA), and 4.3 parts of TBAI were placed in a reaction vessel and stirred at 85° C. for 4 hours. The system (polymerization solution) was slightly thickened by stirring. The polymerization solution was poured into methanol, and the resulting precipitate was filtered, washed and dried to obtain 43.1 parts of crosslinked fine particles (A)-4. The obtained crosslinked fine particles (A)-4 had a number average particle diameter of 2.6 μm. The crosslinked fine particles (A)-4 were insoluble in water and did not have affinity with 10% hydrochloric acid. On the other hand, when it was added to THF, it dispersed easily.

100 parts of MDPA, 30 parts of crosslinked microparticles (A)-4, 30 parts of DEAEMA, and 8.6 parts of TBAI were placed in a reactor and polymerized at 85° C. for 7 hours to obtain a polymerization solution. The resulting polymerization solution was added to methanol, and the resulting precipitate was filtered and washed with methanol to obtain 51.7 parts of PDEAEMA crosslinked microparticles (A)-2. The resulting PDEAEMA crosslinked fine particles (A)-2 had a number average particle diameter of 3.6 μm and an amine value of 126.3 mgKOH/g. This PDEAEMA crosslinked fine particle (A)-2 is a crosslinked fine particle in which two types of polymers, an MMA polymer and a DEAEMA polymer, are grafted. The PDEAEMA crosslinked fine particles (A)-2 did not have affinity with water, but when 10% hydrochloric acid was added, they had affinity with water and dispersed. It also dispersed in THF and MEK.

A quaternary ammonium base was formed using methyl iodide in the same manner as in Reference Example 1, except that PDEAEMA crosslinked fine particles (A)-2 were used instead of PDEAEMA crosslinked fine particles (A)-1, 12.9 parts of polymer-grafted fine particles-7 were obtained. The number average particle diameter measured by dispersing the resulting polymer-grafted fine particles-7 in water was 5.6 μm. The amount of functional groups converted from the amine value of the PDEAEMA crosslinked fine particles (A)-2 was 1.7 mmol/g. Further, the mass ratio of the crosslinked fine particles (A)-1, the grafted polymer (B-1) (polymer having a quaternary ammonium base), and the grafted polymer (B-2) (PMMA) is (A): (B-1):(B-2)=30.6:56.0:13.4.

When the resulting polymer-grafted microparticles-7 were added to MEK, they dispersed with affinity. The polymer-grafted crosslinked fine particles-1 obtained in Reference Example 1 were not compatible with organic solvents and did not swell. On the other hand, the polymer-grafted microparticles-7 have the MMA polymer as a graft chain, and it is considered that the graft chain was dissolved and dispersed in MEK.

( Reference Example 8, Example 9: Polymer graft fine particles-8, 9)
PDEAEMA crosslinked fine particles (A)-3 were prepared in the same manner as in Reference Example 7 described above, except that polyethylene glycol monomethyl ether methacrylate (PME200, average number of repeating oxyethylene groups = 4) was used instead of MMA. 0 copies were obtained. The resulting PDEAEMA crosslinked fine particles (A)-3 had a number average particle diameter of 4.6 μm and an amine value of 116.16 mgKOH/g.

A quaternary ammonium base was formed using methyl iodide in the same manner as in Reference Example 1, except that PDEAEMA crosslinked fine particles (A)-3 were used instead of PDEAEMA crosslinked fine particles (A)-1, 12.7 parts of polymer-grafted fine particles-8 were obtained. The obtained polymer-grafted fine particles-8 had a number average particle diameter of 4.6 μm and a functional group amount of 1.6 mmol/g.

Next, the polymer-grafted microparticles-8 are salt-exchanged using bis(trifluoromethanesulfonyl)imidelithium to form a quaternary ammonium base with a bis(trifluoromethanesulfonyl)imide anion as a counter anion, polymer-grafted microparticles- 9 12.3 parts were obtained. The obtained polymer-grafted fine particles-9 had a number average particle diameter of 4.5 μm. Further, the mass ratio of the crosslinked fine particles (A)-1, the grafted polymer (B-1) (polymer having a quaternary ammonium base), and the grafted polymer (B-2) (PME200) is (A): (B-1):(B-2)=32.3:16.1:51.6.

(Example 10: Application to solid electrolyte)
10 parts of the polymer-grafted fine particles-9 obtained in Example 9 were added to 20 parts of N-methylpyrrolidone (NMP) and stirred to disperse the polymer-grafted fine particles-9 in NMP. After further adding 4.3 parts of bis(trifluoromethanesulfonyl)imidelithium, the mixture was stirred to dissolve the bis(trifluoromethanesulfonyl)imidelithium to obtain a mixture. The resulting mixture was transferred to a petri dish and dried in a vacuum drier at 80° C. to obtain a slightly yellowish thin plate-like film. The resulting film was a composite of polymer-grafted microparticles-9 having a quaternary ammonium base and a lithium salt, and could be used as a solid electrolyte.

The polymer-grafted fine particles of the present invention can introduce many ionic groups into their side chains (graft chains), and can be used as antistatic agents and antifogging agents for plastics. In addition, since it has a high affinity with lithium ions and exhibits properties as an electrolyte, it is expected to be used as a battery material for lithium ion batteries and the like.

Claims (8)

An organic crosslinked fine particle (A) and a linear methacrylate having a structural unit derived from a methacrylate-based monomer (b) having a quaternary ammonium base, one end of which is bound to the crosslinked fine particle (A). and a system polymer (B-1),
The methacrylate-based polymer (B-1) is a graft chain extended from a polymerization initiation group represented by the following general formula (1) in the crosslinked fine particle (A),
The mass ratio of the crosslinked fine particles (A) and the methacrylate polymer (B-1) is (A):(B-1)=10 to 90:10 to 90,
The number average particle diameter is 0.1 to 10 μm,
The crosslinked fine particles (A) are crosslinked fine particles formed of a methacrylate-based polymer (A) having a structural unit derived from a methacrylate-based monomer (a) having a polymerization initiation group represented by the general formula (1). can be,
The counter anion of the quaternary ammonium base is at least one of bis(trifluoromethylsulfonyl)imide anion, bis(fluorosulfonyl)imide anion, tetrafluoroborate anion, and trifluoro(trifluoromethyl)borate anion. polymer-grafted microparticles.

(In the general formula (1), R ₁ represents a hydrogen atom, an alkyl group, or an acyl group, R ₂ represents an alkyl group or an aryl group, and X represents a chlorine atom, a bromine atom, or an iodine atom. Y represents O or NH , * represents a binding site in the methacrylate-based monomer (a) ) further comprising a methacrylate-based polymer (B-2) having no structural unit derived from the methacrylate-based monomer (b), one end of which is bound to the crosslinked fine particles (A);
The methacrylate-based polymer (B-2) is a graft chain extended from a polymerization initiation group represented by the following general formula (1) in the crosslinked fine particle (A),
The crosslinked fine particles (A), the methacrylate-based polymer (B-1), and the methacrylate-based polymer (B-2) have a mass ratio of (A):(B-1):(B-2)=10 to 2. The polymer-grafted microparticles according to claim 1, wherein the ratio is 90:5-85:5-85. 3. The polymer-grafted fine particles according to claim 1, wherein in the general formula (1), _R1 is a methyl group, _R2 is a methyl group, and X is a bromine atom. 4. The polymer-grafted fine particles according to any one of claims 1 to 3, wherein the counter anion of the quaternary ammonium base is bis(trifluoromethylsulfonyl)imide anion. A method for producing polymer-grafted fine particles according to any one of claims 1 to 4,
After polymerizing a monomer containing at least one of dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate in the presence of the crosslinked fine particles (A) and a halogenated quaternary ammonium salt as a catalyst, an alkyl halide is reacted to obtain a second A method for producing polymer-grafted fine particles, comprising the step of forming the methacrylate polymer (B-1) having a quaternary ammonium base. A solid electrolyte comprising the polymer-grafted fine particles according to any one of claims 1 to 4 and a lithium salt. including polymer-grafted microparticles and a lithium salt,
The polymer-grafted fine particles comprise an organic crosslinked fine particle (A) and a structural unit derived from a methacrylate-based monomer (b) having a quaternary ammonium base, one end of which is bound to the crosslinked fine particle (A). A linear methacrylate polymer (B-1) having
The methacrylate-based polymer (B-1) is a graft chain extended from a polymerization initiation group represented by the following general formula (1) in the crosslinked fine particle (A),
The mass ratio of the crosslinked fine particles (A) and the methacrylate polymer (B-1) is (A):(B-1)=10 to 90:10 to 90,
The number average particle diameter is 0.1 to 10 μm,
The crosslinked fine particles (A) are crosslinked fine particles formed of a methacrylate-based polymer (A) having a structural unit derived from a methacrylate-based monomer (a) having a polymerization initiation group represented by the general formula (1). some solid electrolytes.

(In the general formula (1), R ₁ represents a hydrogen atom, an alkyl group, or an acyl group, R ₂ represents an alkyl group or an aryl group, and X represents a chlorine atom, a bromine atom, or an iodine atom. Y represents O or NH , * represents a binding site in the methacrylate-based monomer (a) ) The lithium salt includes lithium tetrafluoroborate, lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and (fluorosulfonyl)-(trifluoromethanesulfonyl). ) The solid electrolyte according to claim 6 or 7, which is at least one selected from the group consisting of imidelithium.