Binder dispersion for non-aqueous secondary battery separators, slurry composition, non-aqueous secondary battery separator, and non-aqueous secondary battery

Abstract

This invention provides an adhesive dispersion with excellent resistance to electrolytes, a slurry composition with excellent solution stability and coatability, a separator with low water content and excellent heat resistance and adhesion to the separator substrate, and a non-aqueous secondary battery with low internal resistance and good cycle characteristics. The problem of this invention can be solved by using an adhesive dispersion for non-aqueous secondary battery separators. The aforementioned adhesive dispersion for non-aqueous secondary battery separators comprises a polymer (A1), a surfactant, and an aqueous medium. The polymer (A1) has an acid value of less than 15 mg KOH / g and contains 50% to 85% by mass of (meth)acrylamide and 15% to 50% by mass of a nonionic vinyl unsaturated monomer (a-1) with a logarithm of 1.9 to 4.2 at 25°C, based on the total mass of the vinyl unsaturated monomer mixture. The polymer has a transmittance of less than 70% for light at a wavelength of 400 nm under the condition of a solid content concentration of 5% by mass.

Description

Adhesive dispersions for non-aqueous secondary battery separators, slurry compositions, non-aqueous secondary battery separators, and non-aqueous secondary batteries. This invention relates to an adhesive for a non-aqueous secondary battery separator, which can be used to form a protective layer for a separator in non-aqueous secondary batteries such as lithium-ion secondary batteries. Additionally, this invention relates to a coating agent comprising the adhesive for the non-aqueous secondary battery separator, a non-aqueous secondary battery separator having a protective layer formed by the coating agent comprising the adhesive for the non-aqueous secondary battery separator, and a non-aqueous secondary battery having the non-aqueous secondary battery separator. Non-aqueous secondary batteries are widely used due to their small size, light weight, high energy density, and ability to be repeatedly charged and discharged. Among them, lithium-ion secondary batteries are widely used in smartphones, tablets, laptops, electric vehicles, and other applications because of their high output, and the demand for lithium-ion secondary batteries is rapidly expanding. For lithium-ion rechargeable batteries, an electrically insulating separator layer is provided between the electrodes to ensure safety during abnormal situations. This separator has a porous structure, which allows lithium ions to pass through under normal conditions, but becomes closed at high temperatures during abnormal reactions, blocking the passage of lithium ions and thus preventing short circuits in the battery. Such separators are made of polyolefin sheets such as polyethylene or polypropylene with porous structures, or coated sheets using these substrates as a base and a protective layer. The protective layer is formed by coating a slurry composition containing non-conductive particles and a binder to impart heat resistance. In recent years, with the further increase in battery capacity, there has been a demand for thin-film separators, and the thin-film nature of the substrate in the aforementioned coated separators is also continuously advancing. On the other hand, if the substrate is made thinner, the heat resistance or durability of the separator is easily further reduced. Therefore, in recent years, research has been conducted on imparting excellent heat resistance or durability to such separators. Patent Document 1 discloses a protective layer that uses a water-soluble polymer formed by polymerizing a compound containing (meth)acrylamide groups and a (meth)acrylate containing hydroxyl groups as an adhesive for the separator. Patent Document 2 discloses a protective layer that uses a water-soluble polymer containing 40% by mass or more of (meth)acrylamide and a particulate polymer as an adhesive for the separator. Patent Document 3 discloses a protective layer that uses a polymer of an acetylated unsaturated monomer containing acetylated groups, an acetylated unsaturated monomer containing carboxyl groups, and an acetylated unsaturated monomer containing carboxyl esters as an adhesive for the separator. [Prior Art Documents] [Patent Documents] [Patent Document 1] Japanese Patent Application Publication No. 2020-24896. [Patent Document 2] International Publication No. 2017 / 026095. [Patent Document 3] International Publication No. 2019 / 065909. [The problem that the invention aims to solve] In cases where water-soluble resin-based adhesives are used for separators, excellent heat resistance and electrolyte resistance are observed. However, there is a risk of poor coatability due to high viscosity. Furthermore, when formulated with inorganic microparticles to create a slurry composition for non-aqueous secondary battery separators, there is a risk of increased internal resistance due to the filling of gaps between the inorganic microparticles. Additionally, high moisture content in the separator can sometimes lead to a decrease in cycle performance due to the reaction between the battery components and moisture. Therefore, the object of the present invention is to provide an adhesive dispersion for a non-aqueous secondary battery separator with excellent electrolyte resistance; a slurry composition for a non-aqueous secondary battery separator containing the adhesive for the non-aqueous secondary battery separator with excellent solution stability and coatability; a non-aqueous secondary battery separator having a protective layer formed from the slurry composition for the non-aqueous secondary battery separator with low water content, excellent heat resistance, and excellent adhesion to the separator substrate; and a non-aqueous secondary battery having the non-aqueous secondary battery separator with low internal resistance and good cycle characteristics. [Means for solving the problem] That is, the present invention relates to an adhesive dispersion for a non-aqueous secondary battery separator, comprising a polymer (A1), a surfactant, and an aqueous medium. The polymer (A1) is a mixture of ethylene unsaturated monomers with an acid value of less than 15 mg KOH / g and containing 50% to 85% by mass of (meth)acrylamide and 15% to 50% by mass of a nonionic ethylene unsaturated monomer (a-1) with a logarithm of 1.9 to 4.2 at 25°C and an octanol / water partition coefficient of 1.9 to 4.2. The transmittance of light at a wavelength of 400 nm does not reach 70% under the condition of a solid content concentration of 5% by mass. Furthermore, this invention relates to the aforementioned adhesive dispersion for non-aqueous secondary battery separators, wherein the polymer (Al) has a storage elastic modulus of 1.0 × 10⁻⁶ at 150°C. 6 Pa or above. In addition, the present invention relates to the aforementioned adhesive dispersion for non-aqueous secondary battery separators, wherein the electrolyte swelling of the polymer (A1) after immersion in a mixed solvent of ethyl carbonate and diethyl carbonate in a volume ratio of 2:3 at 60°C for 72 hours does not reach 2 times. Furthermore, the present invention relates to the aforementioned adhesive dispersion for non-aqueous secondary battery separators, wherein the viscosity at a solid content concentration of 15% by mass is 100 mPa·s or more but less than 15,000 mPa·s. In addition, the present invention relates to a slurry composition for a non-aqueous secondary battery separator, comprising inorganic microparticles and the aforementioned adhesive dispersion for a non-aqueous secondary battery separator. Furthermore, the present invention relates to the aforementioned slurry composition for non-aqueous secondary battery separators, which further comprises polymer (A2) (other than polymer (A1)), wherein polymer (A2) is a particulate polymer with a glass transition temperature of -40°C to 40°C. In addition, the present invention relates to a non-aqueous secondary battery separator, which is formed by providing a protective layer on at least one side of the separator substrate, the protective layer being formed from the aforementioned non-aqueous secondary battery separator slurry composition. In addition, the present invention relates to a non-aqueous secondary battery having the aforementioned non-aqueous secondary battery separator. The following describes the adhesive dispersion for a non-aqueous secondary battery separator, the slurry composition for a non-aqueous secondary battery separator, the non-aqueous secondary battery separator, and the non-aqueous secondary battery based on suitable embodiments of the present invention. However, the present invention is not limited thereto. Each component can be replaced with any component capable of performing the same function, or any component can be added. In addition, in this specification, the numerical range specified by "to" includes the values ​​described before and after "to" as the range of lower and upper limits. In addition, in this specification, "film" or "sheet" is not distinguished according to thickness. In addition, in this specification, when referred to as "(meth)acrylamide" or "(meth)acrylate", unless otherwise specified, it means "acrylamide or methacrylamide" and "acrylate or methacrylate", respectively. Furthermore, the term "ethylene unsaturated monomer" refers to a monomer possessing ethylene unsaturated double bonds. Ethylene unsaturated monomers are classified as (meth)acrylamide, nonionic ethylene unsaturated monomers with a logarithm of 1.9 to 4.2 octanol / water partition coefficient at 25°C (a-1), and other ethylene unsaturated monomers (a-2) that can polymerize with nonionic ethylene unsaturated monomer (a-1). Additionally, in this specification, the nonionic ethylene unsaturated monomer (a-1) with a logarithm of 1.9 to 4.2 octanol / water partition coefficient at 25°C, adhesive dispersions for non-aqueous secondary battery separators, and slurry compositions for non-aqueous secondary battery separators are sometimes abbreviated as nonionic ethylene unsaturated monomer (a-1), adhesive dispersion, and slurry composition, respectively. Moreover, unless otherwise specified, each component appearing in this specification may be a single component or two or more components may be used in combination. Furthermore, the term "non-aqueous secondary battery" refers to a secondary battery in which water is not used in the electrolyte. Examples include lithium-ion batteries (LIBs), sodium-ion batteries, and magnesium batteries. In this specification, LIBs are used as an example of non-aqueous secondary batteries, but the adhesive dispersion, slurry composition, and non-aqueous secondary battery separator of this invention can certainly be applied to non-aqueous secondary batteries other than LIBs. [Adhesive Dispersion for Non-Aqueous Secondary Battery Separators] The adhesive dispersion for non-aqueous secondary battery separators comprises a polymer (A1), a surfactant, and an aqueous medium, and has a light transmittance of less than 70% at a wavelength of 400 nm under a solids content concentration of 5% by mass. Furthermore, the polymer (A1) is a polymer with an acid value of less than 15 mg KOH / g, and contains 50% to 85% by mass of (meth)acrylamide and 15% to 50% by mass of a nonionic ethylene unsaturated monomer (a-1) with a logarithm of 1.9 to 4.2 at 25°C, based on the total mass of ethylene unsaturated monomers. This allows for the preparation of an adhesive dispersion for non-aqueous secondary battery separators with excellent electrolyte resistance, and the slurry composition using the aforementioned adhesive dispersion for non-aqueous secondary battery separators exhibits excellent solution stability and coatability. [Aqueous Medium] Here, "aqueous medium" refers to an aqueous dispersion medium or an aqueous solvent. Water is preferred as the aqueous medium, but water-soluble solvents may also be used as needed. Examples of water-soluble solvents include: alcohols, glycols, Cellosolve derivatives, amino alcohols, amines, ketones, carboxylamines, phosphateamines, sulfoxides, carboxylic acid esters, phosphate esters, ethers, and nitriles. [Surfactant] Examples of surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants, with anionic or nonionic surfactants being preferred. By including a surfactant, the polymer (A1) can be stably dispersed in an aqueous medium, and the slurry composition using the aforementioned surfactant can become a composition with excellent solution stability. The surfactant is preferably present in an amount of 0.05 to 2.0 parts by weight, more preferably 0.05 to 0.5 parts by weight, relative to 100 parts by weight of the polymer (A1), thereby further improving the polymerization stability of the polymer (A1) in an aqueous medium. Examples of anionic surfactants include: sodium oleate and other higher fatty acid salts, alkyl aryl sulfonates such as dodecylbenzenesulfonic acid, alkyl sulfates such as sodium lauryl sulfate, polyoxyethylene alkyl ether sulfates such as sodium polyoxyethylene lauryl ether sulfate, sodium monooctyl sulfosuccinate, sodium dioctyl sulfosuccinate, alkyl sulfosuccinates such as sodium polyoxyethylene lauryl sulfosuccinate and their derivatives, and polyoxyethylene styrene phenyl ether sulfates. In terms of minimizing adverse effects on the food resistance (seasoning resistance, microwave oven resistance) of food packaging sheets, the surfactants mentioned above are preferably alkyl sulfates or alkyl sulfosuccinates, with lauryl sulfate being more preferred, and dioctyl sulfosuccinate being more preferred. Examples of nonionic surfactants include: polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether and polyoxyethylene stearyl ether; polyoxyethylene alkyl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether; sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, and other sorbitan higher fatty acid esters; polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, and other polyoxyethylene higher fatty acid esters; polyoxyethylene monolaurate, polyoxyethylene monostearate, and other polyoxyethylene higher fatty acid esters; glyceryl monoglyceride, glyceryl monostearate, and other glyceryl higher fatty acid esters; polyoxyethylene-polyoxypropylene-block copolymers, polyvinyl alcohol, polyvinylpyrrolidone, and polyoxyethylene styrene ether, etc. Alternatively, polymerizable surfactants with one or more unsaturated double bonds (vinyl, (meth)acrylic) that can be polymerized on free radicals can also be used. Examples of polymerizable anionic surfactants include those with a main backbone of sulfosuccinates, alkyl ethers, alkylphenyl ethers, alkylphenyl esters, (meth)acrylate sulfates, and phosphate esters. Examples of polymerizable nonionic surfactants include those with a main backbone of alkyl ethers, alkylphenyl ethers, and alkylphenyl esters. [Polymer (A1)] Polymer (A1) is a polymer of a mixture of ethylene unsaturated monomers, with an acid value of less than 15 mg KOH / g, and containing at least (meth)acrylamide and a nonionic ethylene unsaturated monomer (a-1) with a logarithm of the octanol / water partition coefficient (Log Kow) of 1.9 to 4.2 at 25°C. The ethylene unsaturated monomer mixture may also contain other ethylene unsaturated monomers (a-2) as needed. Furthermore, the ethylene unsaturated monomer mixture, based on total mass (100% by mass), contains 50% to 85% by mass of (meth)acrylamide and 15% to 50% by mass of ethylene unsaturated monomer (a-1). Furthermore, in this specification, any polymer that meets the aforementioned requirements, even if the glass transition temperature (Tg) is between -40°C and 40°C, is defined as a polymer (A1). The acid value of the polymer (A1) is 15 mg KOH / g or less, more preferably 10 mg KOH / g or less. By achieving this range, when a slurry composition for a non-aqueous secondary battery separator is prepared by blending with inorganic microparticles, the solution stability of the slurry composition becomes better. [(Meth)acrylamide] (Meth)acrylamide contains 50% to 85% by mass, more preferably 60% to 80% by mass, based on the total mass (100% by mass) of the vinyl unsaturated monomers. By containing (meth)acrylamide within the above range, electrolyte resistance and heat resistance can be significantly improved. In addition, when formulated with inorganic microparticles to prepare a slurry composition for a non-aqueous secondary battery separator, the affinity with inorganic microparticles is improved, thereby enhancing the solution stability of the slurry composition. [Nonionic Vinyl Unsaturated Monomer (a-1)] The nonionic vinyl unsaturated monomer (a-1) is a vinyl unsaturated monomer with a logarithm (Log Kow) of 1.9 to 4.2, preferably 2.0 to 4.2, and more preferably 2.2 to 3.5 for the octanol / water partition coefficient. With a Log Kow of 1.9 or higher, the polymer (A1) forms a dispersion in an aqueous medium, and when a slurry composition is prepared, it does not fill the gaps between inorganic particles, resulting in good ion penetration of the separator. This improves battery performance, such as internal resistance and cycle characteristics. Furthermore, when the binder is increased in molecular weight to achieve good heat resistance and adhesion of the separator, high viscosity is suppressed, and the coatability of the slurry composition is excellent. Additionally, the water content of the separator is reduced, resulting in excellent cycle characteristics. Furthermore, by having a Log Kow of less than 4.2, the nonionic vinyl unsaturated monomer (a-1) is incorporated more uniformly, resulting in excellent adhesion and heat resistance. Furthermore, the so-called nonionic vinyl unsaturated monomers refer to vinyl unsaturated monomers that do not have charged functional groups when in an aqueous medium, such as vinyl unsaturated monomers that do not have amine, carboxyl, or sulfonyl groups. Furthermore, the nonionic vinyl unsaturated monomer (a-1) is preferably without crosslinking functional groups, that is, preferably a monomer without crosslinking functional groups. A crosslinking functional group refers to a functional group that imparts a crosslinking structure to the side chains of the polymer; examples include glycidyl groups, alkoxysilyl groups, or vinyl unsaturated groups. Monomers with crosslinking functional groups include monomers with glycidyl groups, monomers with alkoxysilyl groups, and monomers with two or more vinyl unsaturated bonds. The content of the nonionic vinyl unsaturated monomer (a-1) is 15% to 50% by mass, more preferably 20% to 40% by mass, based on the total mass of vinyl unsaturated monomers (100% by mass). With 15% or more of vinyl unsaturated monomer, the moisture content in the separator can be reduced, resulting in excellent circulation characteristics. Furthermore, high viscosity is suppressed, and the coatability of the slurry composition is excellent. Moreover, with 50% or less of vinyl unsaturated monomer, both the adhesion and heat resistance of the separator can be balanced. Nonionic vinyl unsaturated monomers (a-1) with a logarithm (Log Kow) of 1.9 to 4.2 for the octanol / water partition coefficient can be exemplified as follows: tert-butyl acrylate (Log Kow = 2.06), isobutyl acrylate (Log Kow = 2.09), butyl acrylate (Log Kow = 2.23), propyl methacrylate (Log Kow = 2.28), tert-butyl methacrylate (Log Kow = 2.67), amyl acrylate (Log Kow = 2.70), butyl methacrylate (Log Kow = 2.84), amyl methacrylate (Log Kow = 3.03), hexyl acrylate (Log Kow = 3.11), hexyl methacrylate (Log Kow = 3.50), heptyl acrylate (Log Kow = 3.62), 2-ethylhexyl acrylate (Log Kow = 4.01), heptyl methacrylate (Log Kow = 4.01), octyl acrylate (Log Kow = 4.01), etc. Ethylene unsaturated monomers containing straight-chain or branched alkyl groups, such as phenyl acrylate (Log Kow = 4.20); benzyl acrylate (Log Kow = 2.32); phenoxyethyl acrylate (Log Kow = 2.44); phenoxydiethylene glycol acrylate (Log Kow = 2.44); phenyl methacrylate (Log Kow = 2.57); styrene (Log Kow = 2.71); benzyl methacrylate (Log Kow = 2.91); phenoxyethyl methacrylate (Log Kow = 3.02); phenoxydiethylene glycol methacrylate (Log Kow = 3.02); phenoxytetraethylene glycol methacrylate (Log Kow = 3.38); o-methylstyrene (Log Kow = 3.40); α-methylstyrene (Log Kow = 3.46); m-methylstyrene (Log Kow = 3.46); p-methylstyrene (Log Kow = 3.61); phenoxytetraethylene glycol methacrylate (Log Kow = 4.20); Aromatic vinyl unsaturated monomers such as phenoxyhexaethylene glycol acrylate (Log Kow = 3.96) and phenoxyhexaethylene glycol acrylate (Log Kow = 4.15); vinyl unsaturated monomers containing cycloalkyl groups such as dicyclopentenoxyethyl acrylate (Log Kow = 2.57), cyclohexyl acrylate (Log Kow = 2.62), dicyclopentenyl acrylate (Log Kow = 2.98), cyclohexyl methacrylate (Log Kow = 3.06), dicyclopentyl acrylate (Log Kow = 3.29), dicyclopentenyl methacrylate (Log Kow = 3.41), dicyclopentyl methacrylate (Log Kow = 3.73), isobornyl acrylate (Log Kow = 3.78), and isobornyl methacrylate (Log Kow = 4.20); 4-hydroxyvinylbenzene (Log Kow = 2.96).28) Ethylene unsaturated monomers containing hydroxyl groups, such as N-pentoxymethyl-acrylamide (Log Kow = 1.90), N,N-di(propoxymethyl)acrylamide (Log Kow = 1.90), N-pentoxymethyl-methacrylamide (Log Kow = 2.29), N,N-di(propoxymethyl)methacrylamide (Log Kow = 2.29), N,N-di(butoxymethyl)acrylamide (Log Kow = 3.12), and N,N-di(butoxymethyl)methacrylamide (Log Kow = 3.51); 2-butenyl acrylate (Log Kow = 1.91), 1-butenyl acrylate (Log Kow = 1.94), ethylene glycol dimethacrylate (Log Kow = 2.07), and allyl methacrylate (Log Kow = 1.94). Kow = 2.10), 2-methylallyl acrylate (Log Kow = 2.10), divinyl adipate (Log Kow = 2.12), 1,4-butanediol diacrylate (Log Kow = 2.12), diallyl isocyanate (Log Kow = 2.19), 1-methylallyl methacrylate (Log Kow = 2.50), diallyl isophthalate (Log Kow = 2.51), 3-butenyl methacrylate (Log Kow = 2.53), 2-butenyl methacrylate (Log Kow = 2.60), 1,3-methyl-3-butenyl acrylate (Log Kow = 2.62), 1-butenyl methacrylate (Log Kow = 2.63), 2-methylallyl methacrylate (Log Kow = 2.71), 1,4-butanediol dimethacrylate (Log Kow = 2.98), diallyl phthalate (Log Kow = 2.98), Ethylene unsaturated monomers with two or more ethylene unsaturated groups, such as γ-methacryloxymethyltrimethoxysilane (Log Kow = 1.90), γ-methacryloxypropyltrimethoxysilane (Log Kow = 2.42), γ-acryloxypropylmethyldimethoxysilane (Log Kow = 2.47), γ-methacryloxypropylmethyldimethoxysilane (Log Kow = 2.82), vinyltriethoxysilane (Log Kow = 3.12), γ-acryloxypropyltrimethoxysilane (Log Kow = 3.50), and γ-acryloxypropyltriethoxysilane (Log Kow = 3.00), 1,3-methyl-3-butenyl methacrylate (Log Kow = 3.01), and divinylbenzene (Log Kow = 3.93); Kow = 3.50), γ-methacryloxypropylmethyldiethoxysilane (Log Kow = 3).76) γ-methacryloxypropyltriethoxysilane (Log Kow = 3.86) and other alkoxysilyl-containing vinyl unsaturated monomers. Among these, those containing straight-chain or branched alkyl groups are preferred for their good polymerization stability with (meth)acrylamide in aqueous media and for the good dispersibility of polymer (A), especially butyl (meth)acrylate or styrene. The octanol / water partition coefficient (Log Kow) is expressed by the following equation (1), and is used as an indicator of whether a compound X readily partitions in the aqueous phase or the oil phase (octanol). The Log Kow of each vinyl unsaturated monomer can be calculated experimentally using methods such as flask shaking or HPLC (High Performance Liquid Chromatography), or it can be calculated based on chemical structure simulations using the YMB method (property estimation function) of the Hansen solubility parameter software HSPiP. (Equation 1) Log Kow = Log(concentration of compound X in the octanol phase / concentration of compound X in the aqueous phase) [Other Vinyl Unsaturated Monomers (a-2)] Other vinyl unsaturated monomers (a-2) are vinyl unsaturated monomers other than (meth)acrylamide and nonionic vinyl unsaturated monomers (a-1), and are vinyl unsaturated monomers that can polymerize with (meth)acrylamide and nonionic vinyl unsaturated monomers (a-1). Examples of vinyl unsaturated monomers (a-2) include: aromatic vinyl unsaturated monomers such as vinylnaphthalene and phenoxy hexaethylene glycol methacrylate; ethyl (meth)acrylate, propyl acrylate, 2-ethylhexyl methacrylate, octyl methacrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecanyl (meth)acrylate, and so on. Ethylene unsaturated monomers containing straight-chain or branched alkyl groups, such as stearate (meth)acrylate, isostearate (meth)acrylate, and methyl methacrylate resin; ethylene unsaturated monomers containing fluorinated alkyl groups, such as trifluoroethyl (meth)acrylate and heptadecafluorodecyl (meth)acrylate; ethylene unsaturated monomers containing carboxyl groups, such as maleic acid (anhydride), fumaric acid, itaconic acid, citraconic acid, or alkyl or alkenyl monoesters of these acids; β-(meth)acrylic acid oxyethyl monoester, (meth)acrylic acid, butenoic acid, and cinnamic acid; ethylene unsaturated monomers containing carboxyl groups, such as 2-acrylamide-2-methylpropanesulfonic acid, methyl allylsulfonic acid, and olefinic acid. Propylene sulfonic acid, vinyl sulfonic acid, and other sulfonated vinyl unsaturated monomers and their salts; N-methoxymethyl-(meth)acrylamide, N-ethoxymethyl-(meth)acrylamide, N-propoxymethyl-(meth)acrylamide, N-butoxymethyl-(meth)acrylamide, N,N-di(methoxymethyl)(meth)acrylamide, N-ethoxymethyl-N-methoxymethyl(meth)acrylamide, N,N-di(ethoxymethyl)(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, diacetone(methyl)acetone Vinyl unsaturated monomers containing amide groups, such as amide; hydroxyl-containing vinyl unsaturated monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glyceryl mono(meth)acrylate, and allyl alcohol; methoxy polyethylene glycol (meth)acrylate, polyethylene glycol (meth)acrylate, and polyoxyethylene ethyl (meth)acrylate; dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methylethylaminoethyl (meth)acrylate, dimethylaminostyrene, and diethylaminostyrene;Examples include: dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, methylethylaminoethyl methacrylate, tetramethylpiperidin methacrylate, pentamethylpiperidin methacrylate, N,N-dimethylaminopropyl(meth)acrylamide, N,N-diethylaminopropyl(meth)acrylamide, and other amine-containing vinyl unsaturated monomers; glycidyl methacrylate, 3,4-epoxycyclohexyl methacrylate, and other epoxy-containing vinyl unsaturated monomers; acetylaceto(meth)acrylate and other ketone-containing vinyl unsaturated monomers; allyl acrylate, 1-methylallyl acrylate, diallyl phthalate, 3-butenyl acrylate, etc. Ethylene glycol diacrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, diallyl maleate, and other vinyl unsaturated monomers having two or more vinyl unsaturated groups; γ-methacryloxypropyltributoxysilane, γ-acryloxymethyltrimethoxysilane, vinyltrimethoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, and other vinyl unsaturated monomers containing alkoxysilane groups; N-hydroxymethyl(meth)acrylamide, N,N-dihydroxymethyl(meth)acrylamide, alkyl etherified N-hydroxymethyl(meth)acrylamide, and other vinyl unsaturated monomers containing hydroxymethyl groups. As for other vinyl unsaturated monomers (a-2), in terms of the polymerization stability of (meth)acrylamide and the nonionic vinyl unsaturated monomer (a-1) in an aqueous medium, and their good affinity with inorganic particles when forming a slurry composition, methyl (meth)acrylate, hydroxyethyl (meth)acrylate, or (meth)acrylic acid are preferred. When other vinyl unsaturated monomers (a-2) are used in combination, the content of other vinyl unsaturated monomers (a-2) is preferably 5% by mass or less based on the total mass (100% by mass) of the vinyl unsaturated monomers, without impairing the effects of the present invention. [Method for Manufacturing Polymer (A1)] Solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, or any other method can be used as the polymerization method for manufacturing polymer (A1). The surfactant is preferably used in conjunction with the mixture of vinyl unsaturated monomers during the polymerization of polymer (A1). Due to its use during polymerization, the polymerization stability of (meth)acrylamide with the nonionic vinyl unsaturated monomer (a-1) in an aqueous medium is excellent. There is no particular limitation on the concentration of the polymer (A1) solids in the binder dispersion, but it is preferably from 7% to 50% by mass. As a free radical polymerization initiator used in the polymerization reaction, a known oil-soluble or water-soluble polymerization initiator can be used. The free radical polymerization initiator is preferably used at 0.1 to 1.0 parts by weight, and more preferably 0.1 to 0.5 parts by weight, relative to 100 parts by weight of the vinyl unsaturated monomer mixture. By using the above range, the viscosity of the adhesive dispersion can be adjusted to an appropriate range, thereby achieving excellent heat resistance, adhesion, and coatability. There are no particular limitations on oil-soluble polymerization initiators. Examples include: benzoyl peroxide, tributyl peroxide, tributyl hydroperoxide, tributyl peroxide (2-ethylhexanoate), tributyl peroxide-3,5,5-trimethylhexanoate, di-tributyl peroxide, and other organic peroxides; 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylpentanitrile, 2,2'-azobis(4-methoxy-2,4-dimethylpentanitrile), 1,1'-azobis-cyclohexane-1-carboxylonitrile, and other azobis compounds. It is preferable to use a water-soluble polymerization initiator in the polymerization. For example, previously known compounds such as ammonium persulfate (APS), potassium persulfate (KPS), hydrogen peroxide, and 2,2'-azobis(2-methylpropanediamine) dihydrochloride can be used. During polymerization, a reducing agent can also be used in conjunction with the polymerization initiator. By using a reducing agent, the rate of emulsion polymerization is accelerated, and polymerization at low temperatures becomes easier. Examples of reducing agents include: reducing organic compounds such as ascorbic acid, isoascorbic acid, tartaric acid, citric acid, glucose, and metal salts of formaldehyde hyposulfite; reducing inorganic compounds such as sodium thiosulfate, sodium sulfite, sodium bisulfite, and sodium metabisulfite; and ferrous chloride, sodium hydroxide, and thiourea dioxide. These reducing agents are preferably used at 0.05 to 4 parts by weight relative to 100 parts by weight of the ethylene unsaturated monomer. When polymerizing ethylene-based unsaturated monomers, buffers, chain transfer agents, and basic compounds may be used as needed. Examples of buffers include sodium acetate, sodium citrate, and sodium bicarbonate. Examples of chain transfer agents include n-octylthiol, trioctylthiol, n-nonylthiol, trinonylthiol, n-decylthiol, tridecylthiol, n-undecylthiol, tridecylthiol, n-dodecylthiol, tridecylthiol, n-tetralylthiol, tridecylthiol, n-tetradecylthiol, tridecylthiol, n-heptadecylthiol, tridecylthiol, n-hexadecylthiol, and n-hexadecylthiol. Basic compounds are used for neutralization. Examples of such basic compounds include: alkylamines such as trimethylamine, triethylamine, and butylamine; alkanolamines such as 2-dimethylaminoethanol, 2-diethylaminoethanol, diethanolamine, triethanolamine, and aminomethylpropanol; morpholine, ammonia, etc. [Any Components] The adhesive dispersion of the present invention may also contain various additives such as defoamers, leveling agents, preservatives, solvents, crosslinking agents, dispersants, and binders as other arbitrary components, without hindering the effect of the present invention. The preferred storage modulus of polymer (A1) at 150°C is 1.0 × 10⁻⁶. 6 Pa above 1.0 × 10 10 Pa, preferably 1.0 × 10 7 Pa or above. With a storage elastic modulus within the above range at 150°C, the separator made of polymer (Al) exhibits excellent heat resistance, and shrinkage of the separator in high-temperature regions is suppressed, thereby preventing short circuits in non-aqueous secondary batteries, which is therefore superior. When polymer (A1) is immersed in a mixed solvent of ethyl carbonate and diethyl carbonate at a volume ratio of 2:3 for 72 hours at 60°C, the electrolyte swelling degree is preferably less than 2 times, and more preferably less than 1.5 times. Because the electrolyte swelling degree is less than 2 times, the conductivity of lithium ions is not hindered by the swelling of the binder, thus preventing an increase in internal resistance, which is therefore preferable. The adhesive dispersion for the non-aqueous secondary battery separator of the present invention exhibits a transmittance of less than 70% for light at a wavelength of 400 nm, more preferably less than 50%, under a solid content concentration of 5% by mass. Within this range, the dispersibility of the adhesive in an aqueous medium is sufficiently ensured, and when the slurry composition is prepared, the gaps between inorganic particles are not filled, resulting in good ion permeability of the separator. This improves battery performance, such as internal resistance and cycle characteristics. Furthermore, when the adhesive is increased in molecular weight, high viscosity is suppressed, and the coatability of the slurry composition is excellent. Furthermore, light transmittance allows the light source to be split into measured wavelengths using a diffraction grating, and the light incident on the sample (l) The ratio of light (l) transmitted through the sample in 0) is determined by the following equation (2). (Equation 2) Transmittance (%) = (l / l) 0)×100 Furthermore, in the adhesive dispersion for non-aqueous secondary battery separators of the present invention, the polymer (Al) is in particulate form, and the average particle size is preferably 10 nm to 4,000 nm, more preferably 100 nm to 3,000 nm, under the condition of a solid content concentration of 1% by mass. Within this range, the coating properties are good, and when it is formulated with inorganic microparticles as a slurry composition for non-aqueous secondary battery separators, the gaps between the inorganic microparticles are not filled, thus preventing an increase in the internal resistance of the non-aqueous secondary battery. In addition, even with a large molecular weight, high viscosity is suppressed, thus achieving a balance between heat resistance and coating properties, which is preferable. The average particle size can be determined by diluting the adhesive dispersion with water to a solid content concentration of 1% by mass, and measuring approximately 5 ml of this diluted solution using, for example, a dynamic light scattering method (using a device manufactured by NANOTRAC UPA, Microtrac BEL Co., Ltd.). The peak value of the resulting volumetric particle size distribution data (bar chart) is then taken as the average particle size. The viscosity of the adhesive dispersion for non-aqueous secondary battery separators, at a solids concentration of 15% by mass, is preferably 100 mPa·s or higher and not exceeding 15,000 mPa·s, more preferably 500 mPa·s or higher and not exceeding 7,000 mPa·s. Within this range, it possesses a molecular weight sufficient to exhibit heat resistance and adhesion, and the solution stability and coatability of the slurry composition are also excellent. That is, the adhesive dispersion of the present invention is a particulate polymer, thereby suppressing the interaction between resins, and despite its high molecular weight, it achieves excellent workability such as coatability. Viscosity can be determined using a Type B viscometer at 25°C, 20 rpm, and a rotation time of 60 seconds. [Slurry Composition for Non-Aqueous Secondary Battery Separators] The slurry composition for non-aqueous secondary battery separators is used to form a protective layer in non-aqueous secondary battery separators, and includes at least the adhesive dispersion for non-aqueous secondary battery separators of the present invention and inorganic microparticles. Due to the good affinity between the adhesive dispersion and the inorganic microparticles, the slurry composition for non-aqueous secondary battery separators of the present invention exhibits excellent solution stability, heat resistance, and adhesion. Even when the adhesive is increased in molecular weight to achieve good heat resistance and adhesion of the separator, high viscosity is suppressed, and the coating properties of the slurry composition are also excellent. Preferably, the slurry composition includes a polymer (A2) as needed. The polymer (A2) functions as an adhesive component, improving the adhesion to the separator substrate, which is therefore preferable. [Inorganic Particles] Inorganic particles are preferably composed of non-deteriorating inorganic compounds in the electrolyte of non-aqueous secondary batteries. Specific examples of inorganic compounds include: alumina, hydrated alumina, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, silicon dioxide, and ion-conductive glass. One inorganic compound may be used, or two or more may be used in combination. The average particle size of the inorganic microparticles is preferably in the range of 0.01 μm to 10 μm, and more preferably in the range of 0.1 μm to 5 μm. By using inorganic microparticles with the aforementioned average particle size, the protective layer can achieve a higher level of balance between film strength and lithium-ion conductivity. The average particle size of the inorganic microparticles refers to the particle size at which the cumulative value from the smallest particle size side in the particle size distribution based on a volumetric reference (volume distribution) using laser diffraction / scattering or dynamic light scattering methods reaches 50%. The polymer (A1) is preferably used in an amount of 0.1 to 10 parts by mass relative to 100 parts by mass of inorganic particles, and more preferably in an amount of 0.2 to 5 parts by mass. By using the above range, it is possible to maintain the close adhesion between the inorganic particles and the excellent close adhesion between the protective layer and the spacer, and further improve the lithium-ion conductivity of the protective layer and suppress internal resistance. [Polymer (A2)] The slurry composition for the non-aqueous secondary battery separator of the present invention preferably further includes polymer (A2), which is a particulate polymer with a glass transition temperature (Tg) of -40°C to 40°C. Furthermore, polymer (A2) is excluded if it conforms to polymer (A1). When the slurry composition is prepared, polymer (A2) functions as an adhesive component to the substrate. There are no restrictions on the type of polymer (A2) as long as it has a glass transition temperature of -40°C to 40°C and is particulate. Any component such as acrylic resin, styrene acrylic resin, butadiene resin, olefin resin, urethane resin, polyester resin, polysaccharide, and other natural polymers can be used. From the viewpoint of good mixing stability with polymer (A1) and good adhesion to non-conductive particles or olefin substrates, acrylic resin or styrene acrylic resin is preferred. When using polymer (A2), the content of polymer (A2) in the slurry composition is preferably 200 parts by mass or less, and more preferably 10 to 100 parts by mass, relative to 100 parts by mass of polymer (A1). By including polymer (A2) within the above range, the adhesion of the separator substrate is improved, and the cycle characteristics are also excellent. When polymer (A2) is a polymer of vinyl unsaturated monomers, the method for manufacturing polymer (A2) can be the same as the method described in polymer (A1). Polymer (A2) is a particulate polymer dispersed in an aqueous medium, thereby facilitating adhesion to a substrate. Furthermore, the average particle size of polymer (A2) at a solids content concentration of 1% by mass is preferably 50 nm to 500 nm, more preferably 60 nm to 400 nm. By falling within this range, when preparing a slurry composition, the gaps between inorganic particles are not filled, resulting in good ion penetration of the separator. The average particle size can be determined, for example, by dynamic light scattering measurement (using a device manufactured by NANOTRAC UPA, Microtrac BEL Co., Ltd.). The peak value of the obtained volumetric particle size distribution data (bar chart) is taken as the average particle size. In the slurry composition for non-aqueous secondary batteries of the present invention, it is preferred that other polymers besides polymer (A1) and polymer (A2), leveling agents, dispersants, thickeners, defoamers, etc., are included as other arbitrary components. Examples of leveling agents include silicon-based, fluorine-based, metal-based, and succinic acid-based agents. Examples of dispersants include anionic compounds, nonionic compounds, and polymeric compounds. [Manufacturing Method of Slurry Composition] The slurry composition for non-aqueous secondary batteries of the present invention is obtained by mixing the non-aqueous secondary battery separator of the present invention with an adhesive dispersion, inorganic microparticles, and any additives such as polymer (A2). For example, the slurry composition can be obtained by dispersing inorganic microparticles with a dispersant and then mixing the adhesive dispersion with any additives. The non-aqueous secondary battery slurry composition of the present invention can be manufactured using known dispersers and mixers. Specific mixing devices include, for example, dispersers, homogenizers, planetary mixers, and other similar mixers; homogenizers; media dispersers such as paint conditioners, ball mills, sand mills, grinding mills, bead mills, and coball mills; media-free dispersers such as jet mills; and roller mills. Furthermore, a disperser that has undergone treatment to prevent metal contamination is preferred. Ceramic beads such as glass beads, zirconia beads, and alumina beads are preferred as the media. A single disperser or a combination of multiple devices can be used. [Non-aqueous secondary battery separator] The non-aqueous secondary battery separator of the present invention has a protective layer composed of a slurry composition provided on at least one side of the separator substrate. This protective layer improves the heat resistance of the separator, reducing the risk of a short circuit between the two electrodes and an explosion of the non-aqueous secondary battery in the event of overheating. The separator substrate is a sheet or nonwoven fabric with a porous layer containing micropores that allows ions to pass through. Specifically, it can be made from known raw materials such as polyethylene, polyolefins such as polypropylene, cellulose, and aromatic polyamides. The preferred method for forming the protective layer is to apply a coating paste composition. Specific examples of coating methods include: die coating, dip coating, roller coating, doctor blade coating, knife coating, spray coating, gravure coating, screen printing, and electrostatic coating. Furthermore, it is preferable to allow the solvent to dry during coating. Specifically, known drying methods such as air drying, forced air drying, hot air drying, infrared drying, and far-infrared drying can be used. Calendering can also be performed after coating using a flatbed press or calendering rollers. The thickness of the protective layer is preferably from 0.5 μm to 10 μm, more preferably from 1 μm to 5 μm. By falling within the above range, sufficient strength of the protective layer as a coating can be ensured, and excellent battery performance can be achieved. [Non-aqueous secondary battery] Regarding the non-aqueous secondary battery of the present invention, a LIB is used as an example for explanation. The LIB has at least: a battery body having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode; and an electrolyte impregnated in the battery body. The positive and negative electrodes (hereinafter, sometimes referred to as "electrodes") have: a current collector and a composite material layer formed by a composite ink containing an electrode active material as an essential component. Composite inks for general storage devices typically contain active substances and solvents as essential components, and may also include conductive additives and binders as needed. It is preferable to contain as much active substance as possible; for example, the active substance's proportion in the solids component of the composite ink is preferably 80% to 99% by mass. When conductive additives are included, the proportion of the conductive additives in the solids component of the composite ink is preferably 0.1% to 15% by mass. When binders are included, the proportion of the binder in the solids component of the composite ink is preferably 0.1% to 15% by mass. As the current collector, a current collector suitable for various secondary batteries can be selected. Examples of materials for the current collector include metals such as aluminum, copper, nickel, titanium, and stainless steel, as well as alloys of these metals. In the case of a LIB (Liquid Induction Battery), it is preferable to use a current collector made of aluminum at the positive electrode and a current collector made of copper at the negative electrode. Regarding the shape, a flat foil is generally used, but current collectors with roughened surfaces, perforated foil-shaped current collectors, and mesh-like current collectors can also be used. Furthermore, the thickness of the current collector is preferably between 5 μm and 50 μm. There are no particular limitations on the positive electrode active material; metal oxides, metal sulfides, and other metal compounds, as well as conductive polymers, that can dope or intercalate lithium ions can be used. Examples of metal oxides or metal compounds include oxides of transition metals such as Fe, Co, Ni, and Mn, composite oxides with lithium, and inorganic compounds such as transition metal sulfides. Specific examples of metal oxides or metal compounds include MnO and V. 2O 5. V 6O 13 TiO 2. Transition metal oxide powders; composite oxide powders of lithium and transition metals, such as lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide with layered structure, and lithium manganese oxide with spinel structure; lithium iron phosphate materials as lithium oxide compounds with olivine structure; TiS 2. Transition metal sulfide powders such as FeS. There are no particular limitations on the negative electrode active material as long as it can be doped or intercalated with lithium ions. Examples of negative electrode active materials include: metallic Li, alloys such as tin alloys, silicon alloys, and lead alloys; metal oxides such as lithium titanate, lithium vanadate, and lithium silicate; conductive polymers such as polyacetylene and poly(p-phenylene); amorphous carbon materials such as soft carbon and hard carbon; artificial graphite such as highly graphitized carbon materials; carbon powders such as natural graphite; carbon black, mesophase carbon black, resin-calcined carbon materials, vapor-deposited carbon fibers, and carbon fibers. There are no particular limitations on the conductive additives in composite inks, as long as they are conductive carbon materials. Examples of conductive carbon materials include graphite, carbon black, conductive carbon fibers (carbon nanotubes, carbon nanofibers, carbon fibers), and fullerenes. The binder in composite inks is used to bind active substances or conductive carbon materials and other particles together, or to bind conductive carbon materials to current collectors. Examples of adhesives used in composite material inks include: acrylic resins, polyurethane resins, polyester resins, phenolic resins, epoxy resins, phenoxy resins, urea resins, melamine resins, alkyd resins, formaldehyde resins, silicone resins, fluoropolymers, cellulose resins such as carboxymethyl cellulose, synthetic rubbers such as styrene-butadiene rubber or fluororubber, conductive resins such as polyaniline or polyacetylene, and polymers containing fluorine atoms such as polyvinylidene fluoride, polyvinylidene fluoride, and tetrafluoroethylene. Modified forms, mixtures, or polymers of these resins may also be used. Furthermore, film-forming aids, defoamers, leveling agents, preservatives, pH adjusters, viscosity adjusters, etc., can be added to the composite ink as needed. An electrolyte is a liquid in which a lithium-containing electrolyte is dissolved in a non-aqueous solvent. A specific example of an electrolyte is LiBF₂. 4. LiClO 4. LiPF 6. LiAsF 6. LiSbF 6. LiCF 3SO 3. Li(CF) 3SO 2) 2N, LiC 4F 9SO 3. Li(CF) 3SO 2) 3C, LiI, LiBr, LiCl, LiAlCl, LiHF 2. LiSCN, LiBPh 4th grade. Examples of non-aqueous solvents include: carbonates such as ethyl carbonate, propylene carbonate, butyl carbonate, dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; lactones such as γ-butyrolactone, γ-valerolactone, and γ-octanoic acid lactone; ethylene glycol dimethyl ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,2-methoxyethane, 1,2-ethoxyethane, and 1,2-dibutoxyethane; esters such as methyl formate, methyl acetate, and methyl propionate; esters such as dimethyl sulfoxide and cyclobutane; and nitriles such as acetonitrile. Furthermore, the electrolyte is preferably a polymeric electrolyte that is formed into a gel by being held in a polymer matrix. Examples of polymer matrices include: acrylic resins containing polyepoxide segments, polyphosphazene resins containing polyepoxide segments, and polysiloxane resins containing polyepoxide segments. The non-aqueous secondary battery using the above-described components exhibits excellent safety and battery characteristics. The non-aqueous secondary battery of this invention can be used in industrial applications, automotive applications, and mobile applications. [Example] The present invention will now be described in more detail by way of examples, but these examples do not limit the scope of the invention. Furthermore, in the examples, "parts" means "parts by mass," "%" means "% by mass," the values ​​in the table are the mass of the solid components, and empty columns indicate unused components. Furthermore, the methods for determining the average particle size of the inorganic particles and the glass transition temperature (Tg) of the polymer are as follows. [Average particle size of inorganic particles] The average particle size of inorganic particles is determined based on the particle size distribution of the volume standard (volume distribution) using laser diffraction / scattering method, where the cumulative value from the smallest particle size side is 50%. [Glass Transition Temperature] The glass transition temperature of the polymer was determined using a DSC (Differential Scanning Calorimeter, manufactured by TA Instruments). Specifically, an aluminum pot containing approximately 3 mg of dried resin, along with an empty aluminum pot as a reference, was placed on a DSC measuring frame. The temperature at the intersection of the baseline on the low-temperature side of the endothermic phenomenon and the tangent at the inflection point in the resulting DSC curve was measured at a heating rate of 10°C / min. This temperature was defined as the glass transition temperature (Tg). [Preparation of Polymer (A2-1) Dispersion] In a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, 40 parts of ion-exchanged water and 0.2 parts of Aqualon KH-10 (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) as a surfactant were added. Additionally, 1% of a pre-mixed emulsion consisting of 61 parts of 2-ethylhexyl acrylate, 30 parts of methyl methacrylate, 7 parts of styrene, 0.5 parts of methacrylamide, 1.5 parts of acrylic acid, 53 parts of ion-exchanged water, and 1.8 parts of Aqualon KH-10 (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) as a surfactant was added. After raising the internal temperature to 60°C and allowing sufficient nitrogen substitution, 10 parts of a 5% aqueous solution of potassium persulfate and 20 parts of a 1% aqueous solution of anhydrous sodium bisulfite were added to initiate polymerization. The reaction system was maintained at 60°C for 5 minutes. While maintaining the internal temperature at 60°C, the remaining portion of the pre-prepared emulsion, a 5% aqueous solution of potassium persulfate, and the remaining portion of a 1% aqueous solution of anhydrous sodium bisulfite were added dropwise over 1.5 hours, followed by continued stirring for 2 hours. After confirming a conversion rate exceeding 98% by solids content determination, the temperature was cooled to 30°C. 25% ammonia was added to adjust the pH to 8.5, and the solids content was adjusted to 40% using deionized water to obtain a polymer (A2-1) dispersion with a Tg of -12°C. Furthermore, the solids content was determined by baking the residual components at 150°C for 20 minutes. [Example 1] [Preparation of Adhesive Dispersion for Non-Aqueous Secondary Battery Separators] 66 parts acrylamide, 32 parts tributyl methacrylate, 2 parts 1,9-nonanediol diacrylate, 1.0 part 20% Emal 2FG aqueous solution, and 90 parts deionized water were mixed to obtain a mixture. 450 parts water and 30 parts of the above mixture were added to a reaction vessel equipped with a stirrer, thermometer, dropping funnel, and reflux device. The internal temperature of the reaction vessel was then raised to 80°C and nitrogen substitution was fully carried out. 2.0 parts of 10% ammonium persulfate aqueous solution (0.2 parts solids) as an initiator were added to start the reaction. The mixture was added dropwise over 60 minutes while maintaining the internal temperature at 80°C. After the dropwise addition was completed, the reaction was continued at 80°C for 3 hours. After confirming that the conversion rate exceeded 98% by measuring the solids content, the temperature was cooled to 30°C. By adjusting the solids content to 15% using ion-exchanged water, a non-aqueous adhesive dispersion for secondary battery separators containing polymer (A1-1) was obtained. Furthermore, the solids content was determined by baking at 150°C for 20 minutes to obtain the residual components. [Examples 2 to 24, Comparative Examples 1 to 7] Except for the formulation and dosage (parts by mass) shown in the table, a non-aqueous secondary battery separator adhesive dispersion containing polymers (A1-2 to A1-24) or polymers (A3-1 to A3-7) was obtained by the same method as in Example 1. Furthermore, for Examples 4, 6, 12, and Comparative Example 5, after the reaction was completed, 25% ammonia was added to neutralize the resin in an amount equal to the number of carboxyl groups. In Examples 21 and 24, aggregates were observed during polymerization. Comparative Example 7 could not be synthesized due to poor polymerization stability. The physical properties and evaluation results of the obtained polymer and non-aqueous secondary battery separator adhesive dispersions were determined using the following method. The results are shown in the table. [Acid Value] The acid value of a polymer is the number of mg of potassium hydroxide required to neutralize the acidic components contained in 1g of dried resin. It is calculated by potentiometric titration of potassium hydroxide / ethanol solution using an automatic titration apparatus (HIRANUMA "COM-A19") as described in JIS K2501. [Light Transmittance] The obtained adhesive dispersion was adjusted to a solids concentration of 5% using ion-exchanged water and added to a quartz cell with an optical path length of 1 cm. The transmittance spectrum at a wavelength of 400 nm was measured using a spectrophotometer (V-770, manufactured by Japan Spectrophotometer Co., Ltd.). Ion-exchanged water was used as the comparison object. A: Light transmittance less than 50%. B: Light transmittance 50% to less than 70%. C: Light transmittance 70% or more. [Storage Modulus] The obtained adhesive dispersion was dried at 40°C for 72 hours to prepare a film with a thickness of approximately 0.5 mm. The obtained film was cut into strips with a width of 5 mm and a length of 20 mm to prepare samples. The storage modulus at 150°C was measured using a dynamic viscoelasticity measuring device (IT Measurement & Control Co., Ltd.'s "DVA-200"). The measurement conditions are as follows: Measurement mode: Tensile frequency: 10 Hz; Strain: 0.01%; Heating conditions: 10°C / min; A: Storage modulus is 1.0 × 10⁻⁶. 7 Pa or higher. B: Storage elastic modulus is 1.0 × 10⁻⁶. 6 The above is less than 1.0×10 7 Pa. C: Storage elastic modulus not reaching 1.0 × 10⁻⁶ 6 Pa. [Viscosity] The viscosity of the binder dispersion with a solid content of 15% was measured using a Type B viscometer (TVB-10 manufactured by Toki Sangyo) (temperature: 25°C, spindle rotation time: 60 seconds, spindle speed: 20 rpm). A: Viscosity 500 or higher to less than 7000 mPa·s. B: Viscosity 100 or higher to less than 500 mPa·s. B': Viscosity 7000 or higher to less than 15000 mPa·s. C: Viscosity less than 100 mPa·s. C': Viscosity 15000 mPa·s or higher. [Average Particle Size] The average particle size is determined by diluting the polymer solution to 1% by mass of the solid content and measuring approximately 5 ml of the diluted solution using dynamic light scattering (DLS) measurement (measurement apparatus: NANOTRAC UPA, manufactured by Microtrac BEL Co., Ltd.). The peak value of the resulting volumetric particle size distribution data (bar chart) is defined as the average particle size. A: Average particle size ≥100 nm to <3,000 nm. B: Average particle size ≥3,000 nm to <4,000 nm or ≥10 nm to <100 nm. C: Average particle size <10 nm or ≥4,000 nm. [Evaluation of Adhesive Dispersion] [Electrolyte Resistance] Electrolyte resistance refers to the ease with which the polymer melts and swells in an electrolyte, and is evaluated by the electrolyte swelling degree. Generally, the lower the electrolyte swelling degree, the better the electrolyte resistance. The obtained adhesive dispersion was dried at 40°C for 72 hours to prepare a film with a thickness of approximately 1 mm. The film was then cut into 10 mm x 10 mm pieces to form samples, which were then immersed in a mixed solvent of ethyl carbonate and diethyl carbonate at a volume ratio of 2:3 at 60°C for 72 hours. The swelling degree of the film before and after immersion was calculated as follows: Swelling degree (times): = (mass after immersion) / (mass before immersion) A: Swelling degree less than 1.5 times. B: Swelling degree more than 1.5 times but less than 2 times. C: Swelling degree more than 2 times. [Table 1] [Table 2] [Table 3] Furthermore, the abbreviations in the table are as follows. The Log Kow value of the vinyl unsaturated monomer is calculated by converting the structural formula of the vinyl unsaturated monomer into Smiles notation using the YMB method (property calculation function) of the Hansen solubility parameter software HSPip (ver. 5.2.05). [Nonionic Vinyl Unsaturated Monomers (a-1)] t-BA: Tertiary Butyl Acrylate (Log Kow 2.06) BA: Butyl Acrylate (Log Kow 2.23) t-BMA: Tertiary Butyl Methacrylate (Log Kow 4.01) St: Styrene (Log Kow 3.06) 2EHA: 2-Ethylhexyl Acrylate (Log Kow 0.82) 1,4-BDDMA: 1,4-Butanediol Dimethacrylate (Log Kow 2.98) [Other Vinyl Unsaturated Monomers (a-2)] AA: Acrylic Acid (Log Kow 0.2) 2HEA: Hydroxyethyl Acrylate (Log Kow 0.01) 2HEMA: Hydroxyethyl Methacrylate (Log Kow 0.7) MMA: Methyl Methacrylate (Log Kow 1.13) iNA: Isononyl Acrylate (Log Kow 4.44) 1,9-NDDA: 1,9-Nonadiol diacrylate (Log Kow 5.44) [Example 25] [Preparation of Slurry Composition for Non-Aqueous Secondary Battery Separators] 42.4 parts of inorganic microparticles (alumina, average particle size 0.5 μm), 0.5 parts of polycarboxylate ammonium salt (BYK-154) as a dispersant, and 42.7 parts of water were loaded into a bead mill to prepare an alumina dispersion. To the obtained alumina dispersion, 1.1 parts of a binder dispersion containing polymer (A1-1) based on solids content, 0.6 parts of a 4% aqueous solution of carboxymethyl cellulose (CMC, Daicel 1220) as a thickener, 0.3 parts of a silicone activator (BYK-349) as a wetting agent, and 0.2 parts of a silicone defoamer (BYK-018) were added. Water was added to achieve a solids content concentration of 43%. These components were then mixed to prepare a slurry composition for non-aqueous secondary battery separators. [Fabrication of Non-Aqueous Secondary Battery Separator] The above-mentioned slurry composition was coated on one side of the separator substrate (9μm porous polyethylene film) using a doctor blade to a thickness of 3μm. Then, it was dried in an oven at 80°C to obtain a separator with a protective layer. [Cathode Production] Adding LiNi as the positive electrode active material 0.5 Mn 0.3 Co 0.2 O 293 parts of acetylene black (as a conductive agent), 4 parts of polyvinylidene fluoride (as a binder), and 45 parts of N-methylpyrrolidone were mixed to prepare a composite ink for the positive electrode. The obtained composite ink for the positive electrode was coated onto a 20 μm thick aluminum foil, which served as the current collector, using a doctor blade. The foil was then heated and dried at 80°C to adjust the basis weight per unit area of ​​the electrode to 20 mg / cm². 2 Furthermore, calendering is performed using a roll press to produce a composite layer with a density of 3.1 g / cm³. 3 The ultimate. 98 parts of artificial graphite (as the negative electrode active material) and 66.7 parts of a 1.5% aqueous solution of carboxymethyl cellulose (1 part based on solids content) were added to a planetary mixer for mixing. 33 parts of water and 2.08 parts of a 48% aqueous dispersion of styrene-butadiene emulsion (1 part based on solids content) were mixed to prepare a composite ink for the negative electrode. The obtained composite ink for the negative electrode was coated onto a 20 μm thick copper foil, which would serve as the current collector, using a doctor blade. The foil was then heated and dried at 80°C to adjust the basis weight per unit area of ​​the electrode to 12 mg / cm². 2Then, calendering is performed using a roll press to produce a composite layer with a density of 1.5 g / cm³. 3 The negative pole. [Fabrication of Non-Aqueous Secondary Batteries] The positive and negative electrodes are punched into 45mm×40mm and 50mm×45mm pieces, respectively. The positive and negative electrodes are aligned and inserted into an aluminum laminated bag via a separator with a protective layer. After vacuum drying, an electrolyte is injected (LiPF6 is dissolved in a mixed solvent of ethyl carbonate and diethyl carbonate at a volume ratio of 2:3). A laminated non-aqueous secondary battery is made by laminating and sealing an aluminum substrate with a non-aqueous electrolyte (melted at a concentration of 1M). [Examples 26 to 48, Examples 52 to 53, Comparative Examples 8 to 14] The composition and mixing amount (parts by mass) were changed to those shown in the table. Otherwise, the slurry composition for non-aqueous secondary battery separators, non-aqueous secondary battery separators, and non-aqueous secondary batteries were prepared by the same method as in Example 24. [Example 49] An alumina dispersion was prepared by loading 42.4 parts of inorganic microparticles (alumina, average particle size 0.5 μm), 0.5 parts of polycarboxylate ammonium salt (BYK-154) as a dispersant, and 42.7 parts of water into a bead mill. To the obtained alumina dispersion, 1.0 part of a binder dispersion containing polymer (A1-11) based on solids, 0.1 part of a polymer (A2-1) dispersion based on solids, 0.6 parts of a 4% aqueous solution of carboxymethyl cellulose (CMC, Daicel 1220) as a thickener, 0.3 parts of a silicone activator (BYK-349) as a wetting agent, and 0.2 parts of a silicone defoamer (BYK-018) were added. Water was then added to achieve a solids concentration of 43%. These components were then mixed to prepare a slurry composition for a non-aqueous secondary battery separator. [Examples 50 to 51] Except for changing the composition and mixing amount (parts by mass) shown in the table, a slurry composition for a non-aqueous secondary battery separator, a non-aqueous secondary battery separator, and a non-aqueous secondary battery were produced by the same method as in Example 49. Using the following methods, the solution stability and coatability of the obtained slurry composition for non-aqueous secondary battery separators were evaluated. The adhesion between the protective layer and the separator substrate, moisture content, and heat resistance were evaluated using the non-aqueous secondary battery separators. Initial resistance and cycle characteristics were evaluated using a non-aqueous secondary battery. The results are shown in the table. [Evaluation of Slurry Composition] [Solution Stability] The slurry composition was stored at 50°C, and visually observed for agglomeration, precipitation, and separation. [Evaluation Criteria] A: No abnormalities were observed for more than 4 weeks from the start of storage. Excellent. B: Some abnormalities were observed between 1 week and 4 weeks from the start of storage. Good. C: Some abnormalities were observed between 4 days and 1 week from the start of storage. Usable. D: Some abnormalities were observed within 3 days from the start of storage. Potentially problematic. [Copyability] Using the obtained separator, the coatability of the slurry composition is visually observed. [Evaluation Criteria] A: Uniform film thickness and no coverage gaps. Extremely good. B: Unevenness or coverage gaps in less than 5% of the coated area. Good. C: Unevenness or coverage gaps in more than 5% but less than 10% of the coated area. Usable. D: Unevenness or coverage gaps in more than 10% of the coated area. Practical problems exist. [Evaluation of the separator] [Heat resistance of the separator] The separator was cut into MD (traveling direction) 100mm × TD (perpendicular direction) 100mm pieces to prepare the test specimens. The specimens were sandwiched between three sheets of paper and placed in an oven at 150°C for 2 hours. After removing the specimens from the oven and cooling them, the shrinkage rate was calculated as follows. Specimen area (mm²) 2 = (MD length of the sample) × (TD length of the sample) Shrinkage rate (%): = [1 - (area of ​​the sample after heating) / (area of ​​the sample before heating)] × 100 [Evaluation Criteria] A: Shrinkage rate less than 7%. Extremely good. B: Shrinkage rate 7% or more but less than 15%. Good. C: Shrinkage rate 15% or more but less than 30%. Practically usable. D: Shrinkage rate 30% or more. Practically problematic. [Moisture Content of the Separator] The separator was left to stand for 3 days at 23°C and 50% humidity. Moisture was extracted using a vaporization device (VA-100, Mitsubishi Chemical Corporation) at a vaporization temperature of 120°C. The extracted moisture content was measured using a Karl Fischer moisture analyzer (CA-100, Mitsubishi Chemical Corporation). [Evaluation Criteria] A: Moisture content less than 1,500 ppm. Excellent. B: Moisture content 1,500 ppm to less than 2,000 ppm. Good. C: Moisture content 2,000 ppm to less than 3,000 ppm. Practically usable. D: Moisture content 3,000 ppm or more. Practical problems. [Adhesion between the protective layer and the substrate of the separator] The obtained separator with the protective layer was cut into pieces 25mm wide and 100mm long. Double-sided tape was used to adhere the substrate side of the separator to the stainless steel plate. A 18mm wide transparent tape was applied to the protective layer side and rolled over with a 1kg load. After standing for 24 hours at 25°C and 50% humidity, one end of the transparent tape was stretched 180°, and the peel strength was measured using a tensile testing machine (Shimadzu AGS-X, manufactured by Shimadzu Corporation) (peel speed: 10mm / min, unit: N / 18mm width). [Evaluation Criteria] A: Peel strength ≥ 3N / 18mm. Excellent. B: Peel strength ≥ 2N / 18mm to < 3N / 18mm. Good. C: Peel strength ≥ 1.5N / 18mm to < 2N / 18mm. Practically usable. D: Peel strength < 1.5N / 18mm. There are practical problems. [Evaluation of Non-Aqueous Secondary Batteries] [Internal Resistance] Internal resistance is the time it takes for 100ml of air to pass through the sample, evaluated by air permeability. There is a tendency that the shorter the time, the lower the internal resistance, and thus the better the internal resistance. Air permeability was measured using a Gore-type air permeability tester (Toyo Seiki Co., Ltd.'s "G-B3C") according to the method described in JIS P8117. [Evaluation Criteria] A: Less than 250 seconds / 100ml. Extremely good. B: 250 seconds / 100ml or more to less than 270 seconds / 100ml. Good. C: 270 seconds / 100ml or more to less than 280 seconds / 100ml. Practically usable. D: 280 seconds / 100ml or more. Practical problems. [Cycling Characteristics] Constant current and constant voltage charging (cutoff current 0.6mA) was performed in a 50℃ constant temperature bath with a charging current of 60mA and a charging termination voltage of 4.2V. Then, constant current discharging was performed with a discharge current of 60mA until the charging termination voltage of 3.0V was reached. The initial discharge capacity was calculated. After 200 charge-discharge cycles, the discharge capacity retention rate (the percentage of the capacity at the 10th discharge cycle relative to the initial discharge capacity) was calculated. A higher discharge capacity retention rate indicates better cycle characteristics. [Evaluation Criteria] A: Discharge capacity retention rate above 90%. Extremely good. B: Discharge capacity retention rate above 85% but below 90%. Good. C: Discharge capacity retention rate above 80% but below 85%. Practically usable. D: Discharge capacity retention rate below 80%. Practical issues exist. [Table 4] As shown in Table 4, it can be confirmed that the adhesive dispersion for the non-aqueous secondary battery separator of the example has good solution stability and coatability when used to form a slurry composition, good heat resistance and adhesion when made into a separator, and low internal resistance and excellent cycle characteristics when made into a secondary battery. The adhesive dispersion for the non-aqueous secondary battery separator of the aforementioned example contains polymer (A), surfactant, and aqueous medium, and the transmittance of light at 400 nm does not reach 70% under the condition of a solid content concentration of 5% by mass. The aforementioned polymer (A) is polymerized based on the total mass of ethylene unsaturated monomer (a), with 50% to 85% by mass of (meth)acrylamide and 15% to 50% by mass of nonionic ethylene unsaturated monomer (a-1) with a logarithm of octanol / water partition coefficient of 1.9 to 4.2 at 25°C, and the acid value is less than 15 mg KOH / g. On the other hand, in Comparative Example 7, which does not contain surfactant, the polymerization stability is significantly poor. In the use of Comparative Examples 1 to 6 or non-aqueous secondary battery separator slurry compositions, non-aqueous secondary battery separators, and non-aqueous secondary batteries without polymer (A1), the physical properties of any of them were extremely poor, and it was difficult to say that they met the practical level. This application claims priority based on Japanese Patent Application No. 2022-1818, filed on January 7, 2022, and all the contents disclosed in that application are incorporated herein by reference.

Claims

1. An adhesive dispersion for a non-aqueous secondary battery separator, comprising a polymer (A1), an anionic surfactant, and an aqueous medium; wherein the polymer (A1) is a mixture of ethylene unsaturated monomers containing 50% to 85% by mass of (meth)acrylamide and 15% to 50% by mass of a nonionic ethylene unsaturated monomer (a-1) with a logarithm of octanol / water partition coefficient (Log Kow) of 1.9 to 4.2 at 25°C, based on the total mass of the ethylene unsaturated monomer mixture; and having a transmittance of less than 70% for light at a wavelength of 400 nm under a solids content concentration of 5% by mass.

2. The adhesive dispersion for the non-aqueous secondary battery separator as described in claim 1, wherein the aforementioned polymer (A1) has a storage elastic modulus of 1.0 × 10⁶ Pa or higher at 150°C.

3. The adhesive dispersion for the non-aqueous secondary battery separator as described in claim 1 or 2, wherein the electrolyte swelling of the aforementioned polymer (A1) after immersion in a mixed solvent of ethyl carbonate and diethyl carbonate in a volume ratio of 2:3 at 60°C for 72 hours does not reach 2 times.

4. The adhesive dispersion for non-aqueous secondary battery separators as described in claim 1 or 2, wherein the viscosity at a solid content concentration of 15% by mass is 100 mPa·s or more but less than 15,000 mPa·s; the aforementioned viscosity is measured using a type B viscometer at 25°C, a spindle speed of 20 rpm, and a spindle rotation time of 60 seconds.

5. The adhesive dispersion for non-aqueous secondary battery separators as described in claim 3, wherein the viscosity at a solid content concentration of 15% by mass is 100 mPa·s or more but less than 15,000 mPa·s; the aforementioned viscosity was measured using a type B viscometer at 25°C, a spindle speed of 20 rpm, and a spindle rotation time of 60 seconds.

6. A slurry composition for a non-aqueous secondary battery separator, comprising inorganic microparticles and an adhesive dispersion for a non-aqueous secondary battery separator as described in any one of claims 1 to 5.

7. The slurry composition for the non-aqueous secondary battery separator as described in claim 6 further includes a polymer (A2) other than the aforementioned polymer (A1); the aforementioned polymer (A2) is a particulate polymer with a glass transition temperature of -40°C to 40°C.

8. A non-aqueous secondary battery separator, comprising a protective layer provided on at least one side of a separator substrate, wherein the protective layer is formed of a slurry composition for a non-aqueous secondary battery separator as described in claim 6 or 7.

9. A non-aqueous secondary battery comprising a non-aqueous secondary battery separator as described in claim 8.