Composition for non-aqueous secondary battery adhesion, non-aqueous secondary battery adhesive layer, separator, and non-aqueous secondary battery

Abstract

Provided is a composition for non-aqueous secondary battery adhesion, the composition comprising a particulate polymer and a binder, wherein: the particulate polymer includes a unit derived from a Si-containing monomer; the content of the unit derived from the Si-containing monomer is 0.01 mass%-5.0 mass% with respect to the total mass of the particulate polymer; and the swelling degree of the particulate polymer in the electrolyte is 10 times or more.

Description

Adhesive composition for non-aqueous secondary batteries, adhesive layer for non-aqueous secondary batteries, separator, and non-aqueous secondary battery

[0001] The present invention relates to a non-aqueous secondary battery adhesive composition, a non-aqueous secondary battery adhesive layer, a separator, and a non-aqueous secondary battery.

[0002] In recent years, the development of nonaqueous electrolyte batteries, primarily lithium-ion batteries, has been actively pursued. Nonaqueous secondary batteries typically have a microporous membrane (separator) between the positive and negative electrodes. Such separators prevent direct contact between the positive and negative electrodes and allow ions to pass through the electrolyte held within the micropores. To extend the charge-discharge cycle life of secondary batteries and to achieve uniform charge-discharge currents, the separator must also have improved adhesion to the electrodes. Improving the adhesion between the separator and the battery electrodes reduces the likelihood of nonuniform charge-discharge currents and the formation of lithium dendrites, thereby extending the charge-discharge cycle life.

[0003] Patent Document 1 describes a composition for a non-aqueous secondary battery adhesive layer, which contains a particulate polymer and a binder, in which the particulate polymer contains 5 to 50 mass % of (meth)acrylonitrile monomer units and 0.1 to 3.5 mass % of crosslinkable monomer units.

[0004] Patent Document 2 describes a separator for an electricity storage device that includes a substrate and a layer containing a thermoplastic polymer formed on at least a portion of at least one surface of the substrate, in which the thermoplastic polymer contains a copolymer having, as monomer units, 2 to 66% by mass of an ethylenically unsaturated monomer having a chain alkyl group having 8 or more carbon atoms and 34 to 98% by mass of another monomer copolymerizable with the ethylenically unsaturated monomer having a chain alkyl group having 8 or more carbon atoms.

[0005] Patent Document 3 describes a separator for an electricity storage device that includes a substrate and a layer containing a thermoplastic polymer formed on at least a portion of at least one surface of the substrate, in which the thermoplastic polymer includes a copolymer having, as monomer units, an aromatic vinyl compound monomer and a (meth)acrylic acid ester monomer.

[0006] International Publication No. 2017 / 094252 JP 2015-103482 A JP 2015-141840 A

[0007] In the field of secondary batteries, it is generally required to suppress the deterioration of battery characteristics. As a result of investigations, the present inventors have found that suppressing the amount of elution of a polymer contained in an adhesive layer into an electrolyte can contribute to suppressing the deterioration of battery characteristics. In addition, in the field of secondary batteries, peel strength and adhesion after immersion in an electrolyte are also required for the adhesive layer.

[0008] The problem to be solved by the present invention is to provide a nonaqueous secondary battery adhesive composition, a nonaqueous secondary battery adhesive layer, a separator, and a nonaqueous secondary battery, in which the resulting adhesive layer contains a particulate polymer whose amount of elution into an electrolyte solution is reduced and which has excellent peel strength and adhesion after immersion in an electrolyte solution.

[0009] <1> A non-aqueous secondary battery adhesive composition comprising a particulate polymer and a binder, wherein the particulate polymer contains units derived from a Si group-containing monomer, the content of the units derived from the Si group-containing monomer being 0.01% by mass to 5.0% by mass relative to the total mass of the particulate polymer, and the swelling degree of the particulate polymer in an electrolyte solution being 10 times or more. <2> The non-aqueous secondary battery adhesive composition according to <1>, wherein the amount of elution of the particulate polymer in an electrolyte solution is 10.0% by mass or less relative to the total mass of the particulate polymer. <3> The non-aqueous secondary battery adhesive composition according to <1> or <2>, wherein the particulate polymer contains units derived from a (meth)acrylonitrile monomer. <4> The non-aqueous secondary battery adhesive composition according to <3>, wherein the content of the units derived from the (meth)acrylonitrile monomer is 10% by mass to 40% by mass relative to the total mass of the particulate polymer. <5> The nonaqueous secondary battery bonding composition according to any one of <1> to <4>, wherein the particulate polymer contains units derived from an aromatic vinyl compound monomer. <6> The nonaqueous secondary battery bonding composition according to <5>, wherein the content of the units derived from the aromatic vinyl compound monomer is 10% by mass to 40% by mass relative to the total mass of the particulate polymer. <7> The nonaqueous secondary battery bonding composition according to any one of <1> to <6>, wherein the particulate polymer has an average particle size of 100 nm to 800 nm. <8> The nonaqueous secondary battery bonding composition according to any one of <1> to <7>, wherein the particulate polymer has a glass transition temperature of 30°C to 150°C. <9> The nonaqueous secondary battery bonding composition according to any one of <1> to <8>, wherein the particulate polymer contains units derived from a crosslinkable monomer, and the units derived from the crosslinkable monomer contain units derived from the Si group-containing monomer. <10> The nonaqueous secondary battery adhesive composition according to <9>, wherein the content of the units derived from the Si group-containing monomer is 40 mass% or more relative to the total mass of the units derived from the crosslinkable monomer. <11> A nonaqueous secondary battery adhesive layer comprising the nonaqueous secondary battery adhesive composition according to any one of <1> to <10>. <12> A separator comprising a substrate and the nonaqueous secondary battery adhesive layer according to <11>. <13> A nonaqueous secondary battery comprising the separator according to <12>.

[0010] According to the present invention, it is possible to provide a nonaqueous secondary battery adhesive composition, a nonaqueous secondary battery adhesive layer, a separator, and a nonaqueous secondary battery, in which the resulting adhesive layer contains a particulate polymer whose amount of elution into an electrolyte solution is reduced and which has excellent peel strength and adhesion after immersion in an electrolyte solution.

[0011] Hereinafter, a detailed description of an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be given. Note that the present embodiment is merely an example for explaining the present invention, and the present invention is not limited to the following embodiment. The present invention can be implemented with appropriate modifications within the scope of its gist. In the present embodiment, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in the present embodiment in stages, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the Examples. In the present embodiment, a combination of two or more preferred aspects is a more preferred aspect. In the present embodiment, when multiple substances corresponding to each component are present, the amount of each component refers to the total amount of the multiple substances, unless otherwise specified. In the present embodiment, (meth)acrylic is a concept that includes acrylic and methacrylic. The same applies to (meth)acrylate, (meth)acrylonitrile, etc.

[0012] <<Non-aqueous Secondary Battery Adhesive Composition>> The non-aqueous secondary battery adhesive composition of the present embodiment includes a particulate polymer and a binder, the particulate polymer includes units derived from a Si group-containing monomer, the content of the units derived from the Si group-containing monomer is 0.01 mass % to 5.0 mass % with respect to the total mass of the particulate polymer, and the swelling degree of the particulate polymer with respect to an electrolyte solution is 10 times or more.

[0013] The nonaqueous secondary battery adhesive composition of this embodiment, comprising the above-described components, can form a functional layer with excellent adhesion after immersion in an electrolyte solution, resulting in excellent battery characteristics for the resulting nonaqueous secondary battery. In the field of nonaqueous secondary batteries, it is preferable that the polymer contained in the composition for forming the functional layer has a low elution amount into the electrolyte solution. This can suppress deterioration due to increased resistance, side reactions, and the like. Furthermore, in the field of nonaqueous secondary batteries, it is preferable that the polymer contained in the composition for forming the functional layer has a certain degree of swelling. This results in excellent ion permeability, resulting in excellent battery characteristics for the resulting nonaqueous secondary battery. Conventionally, there has been a tendency to increase the amount of crosslinkable monomer added to suppress the elution amount of the polymer into the electrolyte solution. However, when the amount of crosslinkable monomer added is increased, the swelling degree of the polymer is insufficient, leaving room for improvement. The particulate polymer of this embodiment contains a predetermined amount of units derived from a Si-group-containing monomer with a relatively high number of crosslinking points, thereby effectively suppressing elution into the electrolyte solution even in small amounts. In addition, in this embodiment, in order to suppress the amount of elution of the particulate polymer into the electrolyte solution, it is not necessary to excessively increase the crosslinkable monomer, and the amount of crosslinkable monomer added can be relatively suppressed. As a result, the nonaqueous secondary battery adhesive composition of this embodiment has an excellent degree of swelling of the particulate polymer, and the battery characteristics of the obtained nonaqueous secondary battery are excellent.

[0014] <Particulate Polymer> The nonaqueous secondary battery adhesive composition of the present embodiment includes a particulate polymer. The particulate polymer of the present embodiment includes units derived from a Si group-containing monomer, and the content of the units derived from the Si group-containing monomer is 0.01 mass % to 5.0 mass % relative to the total mass of the particulate polymer.

[0015] (Si group-containing monomer) The particulate polymer in this embodiment contains a predetermined amount of units derived from a Si group-containing monomer having a relatively large number of crosslinking points. This makes it possible to suppress elution into the electrolyte solution. Furthermore, in this embodiment, since the amount of polymerization monomer added can be reduced, the particulate polymer has an excellent degree of swelling, and the resulting nonaqueous secondary battery has excellent battery characteristics.

[0016] The Si group-containing monomer is not particularly limited as long as it is a monomer containing a Si group. Examples of Si group-containing monomers include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 8-methacryloxyoctyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and p-styrenetrimethoxysilane. Among the above, preferred Si group-containing monomers include 3-methacryloxypropyltrimethoxysilane and 3-methacryloxypropylmethyldimethoxysilane. These may be used alone or in combination of two or more.

[0017] The content of the units derived from the Si group-containing monomer is 0.01% by mass to 5.0% by mass, relative to the total mass of the particulate polymer. When the content of the units derived from the Si group-containing monomer is 0.01% by mass or more, relative to the total mass of the particulate polymer, excellent blocking resistance is achieved. From the above viewpoint, the content of the units derived from the Si group-containing monomer is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, relative to the total mass of the particulate polymer. When the content of the units derived from the Si group-containing monomer is 5.0% by mass or less, relative to the total mass of the particulate polymer, excellent peel strength and adhesion after immersion in an electrolyte solution are achieved. From the above viewpoint, the content of the units derived from the Si group-containing monomer is preferably 4.0% by mass or less, more preferably 3.0% by mass or less, even more preferably 3.0% by mass or less, even more preferably 1.0% by mass or less, even more preferably 0.8% by mass or less, and even more preferably 0.5% by mass or less, relative to the total mass of the particulate polymer. In this embodiment, the content of units derived from various monomers may be calculated from the blending ratio of various monomers when producing the particulate copolymer, or may be calculated from various spectral data using IR (ATR method) or the like.

[0018] In the nonaqueous secondary battery adhesive composition of this embodiment, the particulate polymer preferably contains units derived from a crosslinkable monomer, and the units derived from the crosslinkable monomer preferably contain units derived from a Si group-containing monomer. In this embodiment, the crosslinkable monomer refers to a monomer having two or more radically polymerizable double bonds and / or a monomer having a functional group that provides a self-crosslinking structure during or after polymerization.

[0019] Examples of monomers having two or more radically polymerizable double bonds include divinylbenzene and polyfunctional (meth)acrylates. Examples of polyfunctional (meth)acrylates include neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, butanediol diacrylate, butanediol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate (A-TMPT), pentaerythritol tetraacrylate, and pentaerythritol tetramethacrylate. Examples of monomers having a functional group that provides a self-crosslinking structure during or after polymerization include the above-mentioned Si group-containing monomers, epoxy group-containing vinyl monomers, amino group-containing vinyl monomers, hydroxyl group-containing vinyl monomers, and alkoxymethyl group-containing vinyl monomers. Examples of epoxy group-containing vinyl monomers include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methyl glycidyl acrylate, and methyl glycidyl methacrylate. Examples of amino group-containing vinyl monomers include N,N-methylenebisacrylamide, diacetoneacrylamide, and N,N-dimethylaminoethylacrylamide. Examples of hydroxyl group-containing vinyl monomers include hydroxyethyl (meth)acrylates such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate, hydroxypropyl (meth)acrylates such as 2-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylates such as 2-hydroxybutyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, di(ethylene glycol) maleate, di(ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis(2-hydroxyethyl) maleate, and 2-hydroxyethyl methyl fumarate. Examples of alkoxymethyl group-containing vinyl monomers include N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, N-butoxymethyl acrylamide, and N-butoxymethyl methacrylamide.These may be used alone or in combination of two or more.

[0020] The content of units derived from the Si group-containing monomer is preferably 40% by mass or more, more preferably 70% by mass or more, and even more preferably 100% by mass, based on the total mass of units derived from the crosslinkable monomer.

[0021] From the viewpoint of excellent battery characteristics, the content of the particulate polymer is preferably 95.0 mass % to 99.99 mass %, more preferably 96.0 mass % to 99.95 mass %, even more preferably 97.0 mass % to 99.93 mass %, and particularly preferably 97.5 mass % to 99.30 mass %, in terms of solid content relative to the total solid content of the nonaqueous secondary battery adhesive composition.

[0022] The particulate polymer of the present embodiment may contain units derived from a monomer other than the Si group-containing monomer. Examples of the other monomer include a (meth)acrylonitrile monomer, an aromatic vinyl compound monomer, a (meth)acrylic acid ester monomer, and an acidic group-containing monomer.

[0023] ((Meth)acrylonitrile Monomer) The particulate polymer in the present embodiment preferably contains units derived from a (meth)acrylonitrile monomer. Examples of the (meth)acrylonitrile monomer include acrylonitrile and methacrylonitrile. By containing a (meth)acrylonitrile monomer, the particulate polymer has better oxidation resistance and adhesiveness. These may be used alone or in combination of two or more.

[0024] The content of units derived from (meth)acrylonitrile monomer is preferably 10% by mass to 40% by mass relative to the total mass of the particulate polymer. When the content of units derived from (meth)acrylonitrile monomer is 10% by mass or more, excellent adhesion after immersion in an electrolyte solution is achieved. From the above viewpoint, the content of units derived from (meth)acrylonitrile monomer is more preferably 15% by mass or more, and even more preferably 20% by mass or more. When the content of units derived from (meth)acrylonitrile monomer is 40% by mass or less, excellent peel strength and blocking resistance are achieved. From the above viewpoint, the content of units derived from (meth)acrylonitrile monomer is more preferably 35% by mass or less, and even more preferably 30% by mass or less.

[0025] (Aromatic vinyl compound monomer) The particulate polymer preferably contains units derived from an aromatic vinyl compound monomer. The aromatic vinyl compound is a compound having an aromatic ring and a vinyl group in the molecule. The aromatic vinyl compound is not particularly limited, but examples thereof include styrene, vinyl toluene, α-methyl styrene, etc. Among the above, the aromatic vinyl compound is preferably styrene. These may be used alone or in combination of two or more.

[0026] The content of units derived from aromatic vinyl compound monomers is preferably 10% by mass to 40% by mass relative to the total mass of the particulate polymer. When the content of units derived from aromatic vinyl compound monomers is 10% by mass or more, excellent blocking resistance is achieved. From the above viewpoint, the content of units derived from aromatic vinyl compound monomers is more preferably 15% by mass or more, and even more preferably 20% by mass or more. When the content of units derived from aromatic vinyl compound monomers is 40% by mass or less, excellent peel strength and adhesion after immersion in an electrolyte solution are achieved. From the above viewpoint, the content of units derived from aromatic vinyl compound monomers is more preferably 35% by mass or less, and even more preferably 30% by mass or less.

[0027] ((Meth)acrylic acid ester monomer) The particulate polymer in the present embodiment preferably contains units derived from a (meth)acrylic acid ester monomer, which provides excellent oxidation resistance.

[0028] The (meth)acrylic acid ester monomer is not particularly limited, but is preferably one having one ethylenically unsaturated bond, and examples thereof include compounds represented by the following formula (1): CH ２ =CR １ -COO-R ２ (1) In formula (1), R １ represents a hydrogen atom or a methyl group, and R ２ represents a monovalent hydrocarbon group which may have a substituent and which may have a heteroatom in the chain. That is, the (meth)acrylic acid ester monomer preferably contains a hydrocarbon ester of (meth)acrylic acid.

[0029] Examples of the monovalent hydrocarbon group include a chain alkyl group which may be linear or branched, a cycloalkyl group, and an aryl group.

[0030] More specific examples of the chain alkyl group include chain alkyl groups having 1 to 5 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and t-butyl groups; and chain alkyl groups having 6 or more carbon atoms, such as n-hexyl, 2-ethylhexyl, and lauryl groups. Examples of the substituent include a hydroxyl group and a phenyl group. There is no particular upper limit on the number of carbon atoms in the chain alkyl group, and it may be, for example, 14.

[0031] The number of carbon atoms constituting the alicyclic ring of the cycloalkyl group is preferably 4 to 8, more preferably 6 or 7, and particularly preferably 6. Examples of the substituent include a methyl group and a t-butyl group.

[0032] An example of the aryl group is a phenyl group.

[0033] An example of the heteroatom is an oxygen atom.

[0034] Specific examples of the (meth)acrylic acid ester monomer include (meth)acrylates having a chain alkyl group such as methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl acrylate, butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate; (meth)acrylates having an aromatic ring such as phenyl acrylate and phenyl methacrylate; etc. These (meth)acrylic acid ester monomers may be used alone or in combination of two or more.

[0035] Specific examples of the (meth)acrylic acid ester monomer include cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, adamantyl acrylate, adamantyl methacrylate, etc. Among these, cyclohexyl acrylate and cyclohexyl methacrylate are preferred.

[0036] In addition, from the viewpoint of improving the polymerization stability of the copolymer, the (meth)acrylic acid ester monomer may contain a (meth)acrylic acid ester monomer having a hydroxyl group as a substituent. Examples of the (meth)acrylic acid ester monomer having a hydroxyl group as a substituent include hydroxyalkyl (meth)acrylates such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; polyethylene glycol acrylate, and polyethylene glycol methacrylate.

[0037] The (meth)acrylic acid ester monomer may be used alone or in combination of two or more kinds.

[0038] The content of the units derived from the (meth)acrylic acid ester monomer is preferably 20% by mass to 70% by mass, more preferably 26% by mass to 59% by mass, further preferably 38% by mass to 49% by mass, and particularly preferably 40% by mass to 46% by mass, relative to the total mass of the particulate polymer.

[0039] (Acidic group-containing monomer) The particulate polymer in the present embodiment preferably contains a unit derived from an acidic group-containing monomer. This provides excellent cushioning properties in a swollen state. Examples of the acidic group include a carboxyl group and a sulfonic acid group. Among these, a carboxyl group is preferred as the acidic group.

[0040] The carboxyl group-containing ethylenically unsaturated monomer is preferably a carboxyl group-containing ethylenically unsaturated monomer. Examples of the carboxyl group-containing ethylenically unsaturated monomer include monocarboxylic acid monomers such as acrylic acid, methacrylic acid, half ester of itaconic acid, half ester of maleic acid, and half ester of fumaric acid; and dicarboxylic acid monomers such as itaconic acid, fumaric acid, and maleic acid. Among the above, the carboxyl group-containing ethylenically unsaturated monomer is preferably acrylic acid, methacrylic acid, and itaconic acid, and more preferably acrylic acid and methacrylic acid. The (meth)acrylic acid ester monomer may be used alone or in combination of two or more.

[0041] Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid.

[0042] The structure of the particulate polymer is not particularly limited, and may be a non-composite polymer substantially composed of a single polymer component, or a composite polymer composed of multiple polymer components. Composite polymers can be easily produced by, for example, polymerizing at least one monomer component according to a conventional method and then polymerizing at least one other monomer component according to a conventional method (two-stage polymerization method). Particles composed of composite polymers have a heterophase structure in which different polymer moieties exist within the particle. Here, a heterophase structure refers to a single particle formed by the physical or chemical bonding of two or more different polymers, and is not a particle having a single-phase structure formed from a single polymer such as a block polymer. A specific example of a heterophase structure is a core-shell structure in which spherical particles have a core and a shell formed from different polymers.

[0043] The swelling degree of the particulate polymer in the electrolyte solution is 10 times or more. This not only provides excellent ion permeability but also excellent adhesion after immersion in the electrolyte solution, resulting in excellent battery characteristics of the resulting nonaqueous secondary battery. From the above viewpoints, the swelling degree of the particulate polymer in the electrolyte solution is preferably 10 times or more, more preferably 11 times or more, and even more preferably 12 times or more. From the viewpoint of suppressing a decrease in adhesion due to a decrease in the strength of the adhesive layer, the swelling degree of the particulate polymer in the electrolyte solution is preferably 25 times or less, more preferably 20 times or less, and even more preferably 16 times or less.

[0044] In this embodiment, the amount of the particulate polymer eluted into the electrolyte solution is suppressed. This makes it possible to suppress an increase in battery resistance and battery deterioration due to side reactions. In this embodiment, the amount of the particulate polymer eluted into the electrolyte solution is preferably 10.0 mass% or less, more preferably 5.0 mass% or less, even more preferably 3.0 mass% or less, and particularly preferably 2.5 mass% or less, based on the total mass of the particulate polymer. In this embodiment, the amount of the particulate polymer eluted into the electrolyte solution may be 0 mass%, may be more than 0 mass%, or may be 0.1 mass% or more.

[0045] The amount of particulate polymer eluted into the electrolyte solution is measured by the following method. An aqueous dispersion containing the particulate polymer is left to stand in an oven at 130°C for 1 hour to dry. A 0.5g piece of the particulate polymer film obtained by drying is cut out to obtain a sample. The obtained sample is placed in a 50mL vial together with 15g of a mixed solvent of ethylene carbonate: ethyl methyl carbonate = 1:2 (mass ratio), and the mixed solvent is allowed to penetrate for 1 day. Thereafter, the sample is removed and washed with the mixed solvent. Subsequently, the sample is left to stand in an oven at 150°C for 3 hours, after which its mass is measured (Wb: g), and the amount of particulate polymer eluted into the electrolyte solution is calculated using the following formula: Amount of particulate polymer eluted into the electrolyte solution (mass%) = Wb / 0.5 x 100

[0046] The average particle diameter of the particulate polymer is preferably 100 nm to 800 nm. When the average particle diameter of the particulate polymer is 100 nm or more, it is possible to prevent the particulate polymer from being embedded in another layer (e.g., a heat-resistant layer) adjacent to the resulting adhesive layer. From the above viewpoint, the average particle diameter of the particulate polymer is more preferably 150 nm or more, even more preferably 200 nm or more, and particularly preferably 250 nm or more. When the average particle diameter of the particulate polymer is 800 nm or less, excellent peel strength is achieved. From the above viewpoint, the average particle diameter of the particulate polymer is more preferably 650 nm or less, even more preferably 500 nm or less, and particularly preferably 400 nm or less.

[0047] The average particle size refers to the 50% particle size (nm) measured using a particle size measuring device based on the average particle size light scattering method (for example, trade name "MICROTRAC UPA150" manufactured by LEED & NORTHRUP).

[0048] The glass transition temperature of the particulate polymer is preferably 30°C to 150°C. When the particulate polymer has a glass transition temperature of 30°C or higher, blocking resistance is excellent. From the above viewpoint, the glass transition temperature of the particulate polymer is more preferably 40°C or higher, and even more preferably 50°C or higher. When the particulate polymer has a glass transition temperature of 150°C or lower, peel strength and wet adhesion are excellent. From the above viewpoint, the glass transition temperature of the particulate polymer is more preferably 130°C or lower, even more preferably 100°C or lower, and particularly preferably 80°C or lower.

[0049] The glass transition temperature can be obtained by measuring a DSC curve and a DDSC curve under a nitrogen atmosphere using a DSC measuring device (manufactured by Shimadzu Corporation, model number: DSC6220).

[0050] The method for producing the particulate polymer is not particularly limited, and for example, it may be produced by a conventional emulsion polymerization method. The emulsion polymerization method is also not particularly limited, and a conventionally known method can be used. For example, the particulate polymer can be obtained by polymerizing the monomer in a dispersion system containing a monomer, a surfactant, a radical polymerization initiator, and other additives used as needed in an aqueous medium.

[0051] The surfactant, radical polymerization initiator, and other additives are described in detail below. The nonaqueous secondary battery adhesive composition of the present embodiment may contain at least one selected from the group consisting of the following surfactants, radical polymerization initiators, and other additives.

[0052] Examples of surfactants include anionic surfactants such as non-reactive alkyl sulfates, polyoxyethylene alkyl ether sulfates, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkyl sulfosuccinates, alkyldiphenyl ether disulfonates, naphthalene sulfonic acid formalin condensates, polyoxyethylene polycyclic phenyl ether sulfates, polyoxyethylene distyrenated phenyl ether sulfates, fatty acid salts, alkyl phosphates, and polyoxyethylene alkylphenyl ether sulfates; and nonionic surfactants such as non-reactive polyoxyethylene alkyl ethers, polyoxyalkylene alkyl ethers, polyoxyethylene polycyclic phenyl ethers, polyoxyethylene distyrenated phenyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, alkylalkanolamides, and polyoxyethylene alkylphenyl ethers. In addition to these, reactive surfactants having an ethylenic double bond introduced into the chemical structure of a surfactant having a hydrophilic group and a lipophilic group may also be used.

[0053] Examples of anionic surfactants among reactive surfactants include ethylenically unsaturated monomers having a sulfonic acid group, a sulfonate group, or a sulfate ester group, and salts thereof. Among these, compounds having a sulfonic acid group or a group that is an ammonium salt or alkali metal salt thereof (ammonium sulfonate group or alkali metal sulfonate group) are preferred. Specific examples include alkylaryl sulfosuccinate salts (e.g., ELEMINOL (registered trademark) JS-20 manufactured by Sanyo Chemical Industries, Ltd., and LATEMUL (registered trademark) S-120, S-180A, and S-180 manufactured by Kao Corporation), polyoxyethylene alkylpropenylphenyl ether sulfate salts (e.g., AQUALON (registered trademark) HS-10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-polyoxyethylene sulfate salts (e.g., ADEKA REASOAP (registered trademark) SE-10N manufactured by ADEKA Corporation), ammonium α-sulfonate salts (e.g., ADEKA REASOAP (registered trademark) SE-10N manufactured by ADEKA Corporation), and ammonium α-sulfonate salts (e.g., ADEKA REASOAP (registered trademark) SE-10N manufactured by ADEKA Corporation). Examples of suitable styrenesulfonate include α-[2-[(allyloxy)-1-(alkyloxymethyl)ethyl]-ω-polyoxyethylene sulfate (e.g., ADEKA REASOAP SR-10 manufactured by ADEKA Corporation), and sulfate of polyoxyethylene polyoxybutylene(3-methyl-3-butenyl)ether (e.g., Latemul PD-104 manufactured by Kao Corporation).

[0054] Furthermore, examples of nonionic surfactants among reactive surfactants include α-[1-[(allyloxy)methyl]-2-(nonylphenoxy)ethyl]-ω-hydroxypolyoxyethylene (e.g., ADEKA REASOAP NE-20, NE-30, and NE-40 manufactured by ADEKA Corporation), polyoxyethylene alkylpropenylphenyl ether (e.g., AQUALON RN-10, RN-20, RN-30, and RN-50 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), α-[2-[(allyloxy)-1-(alkyloxymethyl)ethyl]-ω-hydroxypolyoxyethylene (e.g., ADEKA REASOAP ER-10 manufactured by ADEKA Corporation), and polyoxyethylene polyoxybutylene(3-methyl-3-butenyl)ether (e.g., LATEMUL PD-420 manufactured by Kao Corporation).

[0055] Among the various surfactants mentioned above, reactive surfactants are preferred, anionic reactive surfactants are more preferred, and reactive surfactants having a sulfonic acid group are even more preferred.

[0056] A radical polymerization initiator can initiate addition polymerization of monomers by radical decomposition using heat or a reducing substance. Both inorganic and organic initiators can be used as the radical polymerization initiator. Water-soluble or oil-soluble polymerization initiators can be used as the radical polymerization initiator. Examples of water-soluble polymerization initiators include peroxodisulfates, peroxides, water-soluble azobis compounds, and peroxide-reducing agent redox systems. Examples of peroxodisulfates include potassium peroxodisulfate (KPS), sodium peroxodisulfate (NPS), and ammonium peroxodisulfate (APS). Examples of peroxides include hydrogen peroxide, t-butyl hydroperoxide, t-butylperoxymaleic acid, succinic acid peroxide, and benzoyl peroxide. Examples of water-soluble azobis compounds include 2,2-azobis(N-hydroxyethylisobutyramide), 2,2-azobis(2-amidinopropane)dihydrogen chloride, and 4,4-azobis(4-cyanopentanoic acid). There are no particular limitations on the peroxide in the peroxide-reducing agent redox system. There are no particular limitations on the reducing agent in the peroxide-reducing agent redox system. Examples of reducing agents include sodium sulfoxylate formaldehyde, sodium hydrogen sulfite, sodium thiosulfate, sodium hydroxymethanesulfinate, L-ascorbic acid and its salts, cuprous salts, and ferrous salts. The radical polymerization initiators may be used alone or in combination of two or more.

[0057] When the particulate polymer is obtained by emulsion polymerization, the particulate polymer may be used, for example, as an aqueous dispersion (latex) containing water and particulate particulate polymer dispersed in water. The solid content of the aqueous dispersion is preferably 30% by mass to 70% by mass.

[0058] In order to maintain long-term dispersion stability, the pH of the aqueous dispersion is preferably adjusted to a range of 5 to 12. The pH is preferably adjusted using ammonia, sodium hydroxide, potassium hydroxide, and amines such as dimethylaminoethanol, and more preferably using ammonia (water) or sodium hydroxide.

[0059] The aqueous dispersion may contain, as additives other than the above-mentioned components, solvents such as methanol, ethanol, and isopropyl alcohol, dispersants, lubricants, thickeners, bactericides, and the like.

[0060] <Binder> The nonaqueous secondary battery adhesive composition of this embodiment contains a binder. The binder can be used without any particular limitation, and examples thereof include a particulate polymer and a water-soluble polymer. The particulate polymer used as the binder is a particulate polymer other than the particulate polymers described in the above section <Particulate Polymer>. Examples of particulate polymers used as the binder include styrene-butadiene polymer (SBR), butadiene rubber (BR), acrylic rubber (NBR), and polymers containing (meth)acrylic acid ester monomer units. Among the above, polymers containing (meth)acrylic acid ester monomer units are preferred.

[0061] Examples of the water-soluble polymer include carboxymethyl cellulose, xanthan gum, poly(meth)acrylamide, water-soluble (meth)acrylic polymer, polyacid anhydride, polysulfonic acid, etc. Among these, polyacrylamide is preferred.

[0062] From the viewpoint of excellent adhesion to the electrode active material, the content of the binder is preferably 0.01 mass % to 5.0 mass %, more preferably 0.05 mass % to 4.0 mass %, and even more preferably 0.07 mass % to 0.3 mass %, in terms of solid content, relative to the total solid content of the nonaqueous secondary battery adhesive composition.

[0063] <<Non-aqueous secondary battery adhesive layer>> The non-aqueous secondary battery adhesive layer of this embodiment (also simply referred to as adhesive layer in this embodiment) contains the non-aqueous secondary battery adhesive composition of this embodiment. Because the adhesive layer of this embodiment contains the non-aqueous secondary battery adhesive composition of this embodiment, it contains a particulate polymer whose amount of elution into an electrolyte solution is reduced, and is excellent in peel strength and adhesion after immersion in an electrolyte solution.

[0064] The method for producing the adhesive layer is not particularly limited. For example, the method described in JP-A-2016-167455 may be adopted.

[0065] <<Separator>> The separator of this embodiment includes a substrate and the nonaqueous secondary battery adhesive layer of this embodiment. Examples of materials for the substrate include polyolefin-based resins. Examples of polyolefin-based resins include homopolymers such as polyethylene and polypropylene, copolymers, and mixtures thereof. Examples of polyethylene include low-density, medium-density, and high-density polyethylenes, with high-density polyethylene being preferred from the viewpoints of puncture resistance and mechanical strength. Two or more of the above materials may be mixed together to form the substrate.

[0066] The thickness of the substrate is preferably 0.5 μm to 40 μm, more preferably 1 μm to 30 μm, and even more preferably 1 μm to 10 μm. When the thickness of the substrate is within the above range, the resistance caused by the separator in an electricity storage device such as a battery becomes smaller.

[0067] There are no particular limitations on the method for producing the separator, and for example, the method described in JP 2016-167455 A may be used.

[0068] <<Non-aqueous secondary battery>> The non-aqueous secondary battery of this embodiment includes the separator of this embodiment. The non-aqueous secondary battery of this embodiment may include a positive electrode and a negative electrode as electrodes. The adhesive layer in the separator of this embodiment may be adhered to the positive electrode or the negative electrode.

[0069] The positive electrode material (positive electrode active material) is not particularly limited, but for example, LiCoO ２ , LiNiO２ , spinel-type LiMnO ４ , olivine-type LiFePO ４ Examples of the negative electrode material (negative electrode active material) include, but are not limited to, carbon materials such as graphite, non-graphitizable carbon, easily graphitizable carbon, and composite carbon bodies; silicon, tin, metallic lithium, and various alloy materials. The positive electrode and the negative electrode may each include a current collector, and examples of the positive electrode current collector include aluminum foil, and examples of the negative electrode current collector include copper foil.

[0070] The nonaqueous secondary battery of this embodiment includes a nonaqueous electrolyte. The nonaqueous electrolyte is not particularly limited, but an electrolyte solution in which an electrolyte is dissolved in an organic solvent can be used. Examples of the organic solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Examples of the electrolyte include LiClO ４ , LiBF ４ , LiPF ６ Examples of lithium salts include:

[0071] There are no particular limitations on the method for producing a non-aqueous secondary battery, and for example, the method described in JP 2016-167455 A may be adopted.

[0072] Hereinafter, the present embodiment will be described in more detail with reference to specific examples and comparative examples, but the present invention is not limited to the following examples and comparative examples in any way.

[0073] [Example] <Preparation of Particulate Polymer> 87 parts by mass of ion-exchanged water and 0.01 parts by mass of Newcol 707SF as an emulsifier were charged into a reactor equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer. Next, the temperature inside the reaction vessel was raised to 80°C, and 0.15 parts by mass of a 2% aqueous solution of ammonium persulfate was added while maintaining the temperature at 80°C. Five minutes after the addition of the aqueous ammonium persulfate solution was completed, the emulsion was added dropwise from the dropping tank to the reaction vessel over 150 minutes. The emulsion was prepared by mixing a mixture containing each monomer listed in Table 1 or Table 2 in amounts such that the content in the resulting particulate polymer would be as listed in Table 1 or Table 2, 0.7 parts by mass of Newcol 707SF as an emulsifier, 0.15 parts by mass of a 2% aqueous solution of ammonium persulfate, and 150 parts by mass of ion-exchanged water, using a homomixer, for 5 minutes. After the emulsion was added dropwise, the temperature inside the reaction vessel was maintained at 80°C for 90 minutes, and then cooled to room temperature. The resulting emulsion was adjusted to pH 9.0 with an aqueous ammonium hydroxide solution (25% by mass), yielding a 40% by mass aqueous dispersion. The Tg, average particle size, swelling degree in the electrolyte, and amount of elution of the particulate polymer in the resulting aqueous dispersion were measured.

[0074] <Preparation of Slurry Composition> 98.9 parts (solid content equivalent) of an aqueous dispersion of a particulate polymer, 0.1 parts (solid content equivalent) of "Hermid B-15" (manufactured by Harima Chemicals Co., Ltd., binder, anionic polyacrylamide), and 1 part (solid content equivalent) of "Nopco Wet 50" (San Nopco Ltd.) as a wetting agent were mixed in a stirring vessel to obtain a mixture. The obtained mixture was diluted with ion-exchanged water to obtain a slurry composition (solid content concentration 10% by mass).

[0075] <Production of separator with adhesive layer> A separator substrate made of a porous polyethylene substrate was prepared. The slurry composition prepared by the above method was applied to one side of the separator substrate to a thickness of 0.5 μm and a basis weight of 0.4 g / m ２ The mixture was then dried with hot air at 60° C. for 1 minute, thereby obtaining a separator having an adhesive layer.

[0076] [Examples 2 to 19, Comparative Examples 1 to 4] Particulate polymers, slurry compositions, and separators with adhesive layers were obtained in the same manner as in Example 1, except that the types and amounts of the monomers to be added were changed as shown in Table 1 or Table 2.

[0077] Example 20 Preparation of Core-Shell Particles 87 parts by mass of ion-exchanged water and 0.01 parts by mass of Newcol 707SF emulsifier were added to a reactor equipped with a stirrer, reflux condenser, dropping tank, and thermometer. The temperature inside the reaction vessel was then raised to 80°C, and 0.15 parts by mass of a 2% aqueous solution of ammonium persulfate was added while maintaining the temperature at 80°C. Five minutes after the addition of the aqueous ammonium persulfate solution was completed, the core emulsion was added dropwise from the dropping tank to the reaction vessel over 150 minutes. After the dropwise addition of the core emulsion was completed, the temperature inside the reaction vessel was maintained at 80°C for 30 minutes. The shell emulsion was then added dropwise from the dropping tank to the reaction vessel over 30 minutes. After the dropwise addition of the shell emulsion was completed, the mixture was cooled to room temperature. The pH of the resulting emulsion was adjusted to 9.0 with an aqueous ammonium hydroxide solution (25% by mass aqueous solution) to obtain a 40% by mass aqueous dispersion. The particulate polymer in the resulting aqueous dispersion was measured for Tg, average particle size, swelling degree in an electrolytic solution, and amount of elution. Using the resulting aqueous dispersion of the particulate polymer, a slurry composition and a separator with an adhesive layer were obtained in the same manner as in Example 1.

[0078] Comparative Example 5 A particulate polymer, a slurry composition, and a separator with an adhesive layer were obtained in the same manner as in Example 20, except that the type and amount of the monomer to be added were changed as shown in Table 3.

[0079] <Glass transition temperature of particulate polymer> An appropriate amount of the aqueous dispersion containing the particulate polymer was placed in an aluminum dish and dried for 1 hour in a hot air dryer at 130°C. Approximately 10 mg of the dried film after drying was placed in an aluminum container for measurement, and a DSC curve and a DDSC curve were obtained under a nitrogen atmosphere using a DSC measurement device (Shimadzu Corporation, model number: DSC6220). The glass transition temperature was obtained from the obtained DSC curve and DDSC curve.

[0080] <Average particle size of particulate polymer> The 50% particle size (nm) was measured using a particle size measuring device based on a light scattering method (manufactured by LEED & NORTHRUP, trade name "MICROTRAC UPA150"), and this was taken as the average particle size.

[0081] <Swelling degree of particulate polymer in electrolyte solution> An aqueous dispersion containing a particulate polymer was left to stand at 25°C for 120 hours and dried. A 0.5g portion of the particulate polymer film obtained by drying was cut out to obtain a sample. The obtained sample was placed in a 50mL vial together with 15g of a mixed solvent of ethylene carbonate: ethyl methyl carbonate = 1:2 (mass ratio), and the mixed solvent was allowed to penetrate for one day. Thereafter, the sample was taken out and washed with the mixed solvent, and its mass (Wa:g) was measured. The swelling degree of the particulate polymer in electrolyte solution was calculated using the following formula: Swelling degree of particulate polymer in electrolyte solution (times) = Wa / 0.5

[0082] <Amount of elution of particulate polymer into electrolyte solution> An aqueous dispersion containing a particulate polymer was left to stand in an oven at 130°C for 1 hour and dried. A 0.5g piece of the particulate polymer film obtained by drying was cut out to obtain a sample. The obtained sample was placed in a 50mL vial together with 15g of a mixed solvent of ethylene carbonate: ethyl methyl carbonate = 1:2 (mass ratio), and the mixed solvent was allowed to penetrate for 1 day. Thereafter, the sample was taken out and washed with the mixed solvent. Subsequently, the sample was left to stand in an oven at 150°C for 3 hours, after which the mass was measured (Wb: g), and the amount of elution of the particulate polymer into the electrolyte solution was calculated using the following formula: Amount of elution of particulate polymer into the electrolyte solution (mass%) = Wb / 0.5 x 100

[0083] <Peel Test> A separator coated with an adhesive layer on one side was cut into a rectangle measuring 1 cm wide x 7 cm long to prepare a test specimen. To measure peel strength, a metal plate and the coated side of the separator were attached with double-sided tape, and one end of the separator was pulled vertically upward at a pulling rate of 100 mm / min to measure the stress when peeled. This measurement was performed five times, and the average stress value was calculated as the peel strength, which was evaluated according to the following criteria. A higher peel strength indicates that the water-soluble polymer firmly bonds the particles to the separator. (Evaluation Criteria) A: The peel strength was 4.0 N / m or more. B: The peel strength was 0.5 N / m or more but less than 4.0 N / m. C: The peel strength was 0.1 N / m or more but less than 0.5 N / m. D: The peel strength was less than 0.1 N / m.

[0084] <Wet Adhesion Strength> The negative electrode and the separator coated with an adhesive layer on one side were each cut into a 10 mm x 100 mm strip. Then, the negative electrode composite layer of the negative electrode was placed on the surface of the adhesive layer of the separator and fixed. This laminate was used as a test specimen. The test specimen was placed in a laminate packaging material together with approximately 400 μL of electrolyte. After 5 hours, the test specimen together with the laminate packaging material was pressed at 80°C and a pressure of 1.5 MPa for 20 minutes. The electrolyte was a mixed solvent of EC and DEC (EC / DEC (volume mixing ratio at 25°C) = 60 / 40) with LiPF as a supporting electrolyte. ６The electrolyte solution was a solution containing 1 mol / L of ethylenediaminetetraacetic acid (ETA-2) dissolved in the electrolyte. The test specimen was then removed, and the electrolyte adhering to the surface was wiped off. The test specimen was placed with the negative electrode current collector side facing downward, and cellophane tape was applied to the negative electrode current collector side. The cellophane tape used was specified in JIS Z1522. The cellophane tape was fixed to a horizontal test table. One end of the adhesive-layered single-sided separator was then pulled vertically upward at a pulling rate of 100 mm / min to measure the peel stress. This measurement was performed five times, and the average stress was calculated as the peel strength. The wet adhesive strength was evaluated according to the following criteria. A higher peel strength indicates better adhesion of the separator in the electrolyte and stronger adhesion to the electrode (negative electrode). (Evaluation Criteria) A: Peel strength was 2.1 N / m or more. B: The peel strength was 1.0 N / m or more and less than 2.1 N / m. C: The peel strength was 0.3 N / m or more and less than 1.0 N / m. D: The peel strength was less than 0.3 N / m.

[0085] <Blocking Resistance> A separator coated on one side with an adhesive layer was cut into a square measuring 5 cm wide x 5 cm long to prepare a test specimen. Two test specimens were stacked with the coated surfaces facing each other (unpressed sample), and another sample was stacked and then placed under a pressure of 60°C and 1.0 MPa (pressed sample). These samples were each left for 24 hours. After 24 hours, the adhesion state (blocking state) of the stacked double-sided separators with adhesive layers was visually inspected, and the blocking resistance was evaluated according to the following criteria. (Evaluation Criteria) A: In the pressed sample, the separators did not block. B: In the pressed sample, the separators blocked but peeled when one side was lifted. C: In the pressed sample, the separators blocked and did not peel even when lifted. D: In the unpressed sample, the separators blocked.

[0086]

[0087]

[0088]

[0089] The details of each term in Tables 1, 2 and 3 are as follows: AN: acrylonitrile St: styrene 2-EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate CHMA: cyclohexyl methacrylate MAA: methacrylic acid AA: acrylic acid KBM-503: 3-methacryloxypropyltrimethoxysilane KBM-502: 3-methacryloxypropylmethyldimethoxysilane A-TMPT: trimethylolpropane triacrylate

[0090] As shown in Tables 1 and 2, in the examples using nonaqueous secondary battery adhesive compositions containing a particulate polymer and a binder, the particulate polymer containing units derived from a Si group-containing monomer, the content of the units derived from the Si group-containing monomer being 0.01% by mass to 5.0% by mass relative to the total mass of the particulate polymer, and the swelling degree of the particulate polymer in the electrolyte solution being 10 times or more, the resulting adhesive layer contained a particulate polymer with reduced elution into the electrolyte solution, and had excellent peel strength and adhesive properties after immersion in the electrolyte solution (wet adhesive strength). On the other hand, in Comparative Example 1, in which the particulate polymer did not contain a Si group-containing monomer, the amount of elution into the electrolyte solution could not be reduced. Furthermore, in Comparative Example 2, in which the content of the units derived from the Si group-containing monomer was more than 5.0% by mass relative to the total mass of the particulate polymer and the swelling degree of the particulate polymer in the electrolyte solution was not 10 times or more, the peel strength and wet adhesive strength were poor. Furthermore, Comparative Examples 3 and 4, in which the swelling degree of the particulate polymer in the electrolyte solution was not 10 times or more, were inferior in wet adhesive strength. Example 20 and Comparative Example 5, in which the particulate polymer had a core-shell structure, also gave the results shown in Table 3. That is, in Example 20, the adhesive layer obtained contained a particulate polymer whose amount of elution into the electrolyte solution was suppressed, and was excellent in peel strength and adhesiveness after immersion in the electrolyte solution (wet adhesive strength). On the other hand, Comparative Example 5, in which the swelling degree of the particulate polymer in the electrolyte solution was not 10 times or more, was inferior in peel strength and wet adhesive strength.

[0091] The disclosure of Japanese Patent Application No. 2024-055529, filed on March 29, 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A non-aqueous secondary battery adhesive composition comprising a particulate polymer and a binder, wherein the particulate polymer contains units derived from a Si group-containing monomer, the content of the units derived from the Si group-containing monomer being 0.01% by mass to 5.0% by mass relative to the total mass of the particulate polymer, and the swelling degree of the particulate polymer in an electrolyte solution is 10 times or more.

2. The non-aqueous secondary battery adhesive composition according to claim 1, wherein the amount of elution of the particulate polymer into the electrolyte is 10.0 mass % or less based on the total mass of the particulate polymer.

3. The non-aqueous secondary battery adhesive composition according to claim 1 or 2, wherein the particulate polymer contains units derived from a (meth)acrylonitrile monomer.

4. The non-aqueous secondary battery adhesive composition according to claim 3, wherein the content of the units derived from the (meth)acrylonitrile monomer is 10% by mass to 40% by mass relative to the total mass of the particulate polymer.

5. The non-aqueous secondary battery adhesive composition according to claim 1 or 2, wherein the particulate polymer contains units derived from an aromatic vinyl compound monomer.

6. The nonaqueous secondary battery adhesive composition according to claim 5, wherein the content of the units derived from the aromatic vinyl compound monomer is 10% by mass to 40% by mass relative to the total mass of the particulate polymer.

7. The non-aqueous secondary battery adhesive composition according to claim 1 or 2, wherein the particulate polymer has an average particle size of 100 nm to 800 nm.

8. The non-aqueous secondary battery adhesive composition according to claim 1 or 2, wherein the particulate polymer has a glass transition temperature of 30°C to 150°C.

9. The non-aqueous secondary battery adhesive composition according to claim 1 or 2, wherein the particulate polymer contains units derived from a crosslinkable monomer, and the units derived from the crosslinkable monomer contain units derived from the Si group-containing monomer.

10. The non-aqueous secondary battery adhesive composition according to claim 9, wherein the content of the units derived from the Si group-containing monomer is 40 mass % or more relative to the total mass of the units derived from the crosslinkable monomer.

11. A non-aqueous secondary battery adhesive layer comprising the non-aqueous secondary battery adhesive composition according to claim 1 or 2.

12. A separator comprising: a substrate; and the nonaqueous secondary battery adhesive layer according to claim 11.

13. A non-aqueous secondary battery comprising the separator of claim 12.

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