Adhesive compositions, adhesive electrodes, adhesive separators, and secondary batteries

Abstract

To provide an adhesive composition with excellent stability. [Solution] A particulate polymer, a radical scavenger, and a solvent, An adhesive composition comprising, The particulate polymer comprises a first constituent unit derived from a first monomer, The solubility of the first monomer in water at 20°C is 20.0 g / L or more and 230.0 g / L or less. The amount of the first constituent unit is 10% by mass or more, based on the total mass of all constituent units constituting the particulate polymer. The solubility of the radical scavenger in water at 20°C is 0.1 g / L or more. An adhesive composition in which the amount of the radical scavenger is 0.0001% by mass or more and 5% by mass or less, based on the mass of the particulate polymer.

Description

Technical Field

[0001] The present invention relates to an adhesive composition, an adhesive electrode, an adhesive separator, and a secondary battery. It relates thereto.

Background Art

[0002] In recent years, the spread of devices having a high-capacity power storage medium, typified by electric vehicles, has been remarkable. As the power source for these devices, secondary batteries such as lithium-ion secondary batteries are often used. The members of a lithium-ion secondary battery are generally manufactured by applying a particle dispersion liquid to the surface of a positive electrode, a negative electrode, or a separator and drying to form a coating film. At this time, an adhesive in which a polymer is dissolved or an adhesive in which particulate polymers are dispersed may be used for the purpose of adhering the particles to each other or the members to each other. As the polymer particles and the manufacturing method thereof, for example, the contents described in Patent Documents 1 to 4 are known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] The polymers contained in adhesives are generally synthesized by radical polymerization. In radical polymerization, a radical generator is used as an initiator, but the initiator is rarely completely consumed during polymerization, and a certain amount of initiator remains even after polymerization is complete. Similarly, the monomers used in polymerization are rarely completely consumed, and a certain amount of monomer remains even after polymerization is complete. During storage of the adhesive, if the remaining monomers separate from the synthesized polymer and migrate into the solvent contained in the adhesive, polymerization may be triggered by the radicals of the remaining initiator, resulting in by-products and potentially causing problems such as changes in the viscosity of the adhesive and the formation of aggregates.

[0005] Therefore, the present invention aims to provide an adhesive composition with excellent stability. [Means for solving the problem]

[0006] We have found that when residual monomers tend to migrate into the solvent contained in the adhesive, using a radical scavenger that is easily soluble in the solvent can suppress side reactions caused by residual monomers and residual initiators, thereby improving the stability of the adhesive composition.

[0007] The present invention includes the following embodiments. [1] A particulate polymer, a radical scavenger, and a solvent. An adhesive composition comprising, The particulate polymer comprises a first constituent unit derived from a first monomer, The solubility of the first monomer in water at 20°C is 20.0 g / L or more and 230.0 g / L or less. The amount of the first constituent unit is 10% by mass or more, based on the total mass of all constituent units constituting the particulate polymer. The solubility of the radical scavenger in water at 20°C is 0.1 g / L or more. An adhesive composition in which the amount of the radical scavenger is 0.0001% by mass or more and 5% by mass or less, based on the mass of the particulate polymer. [2] The adhesive composition according to [1], wherein the radical scavenger comprises at least one selected from the group consisting of oxoacid compounds, phenol compounds, quinone compounds, and polyvalent metal salt compounds. [3] The adhesive composition according to [1] or [2], wherein the first monomer comprises at least one selected from the group consisting of vinyl cyanide monomer, carboxyl group-containing monomer, (meth)acrylamide monomer, and (meth)acrylic acid ester monomer. [4] The particulate polymer further comprises a second constituent unit derived from a second monomer, The adhesive composition according to any one of [1] to [3], wherein the second monomer is a crosslinkable monomer copolymerizable with the first monomer. [5] The adhesive composition according to [4], wherein the amount of the second constituent unit is 0.001% by mass or more and 5% by mass or less, based on the mass of all constituent units constituting the particulate polymer. [6] The particulate polymer further comprises a third constituent unit derived from a third monomer, The adhesive composition according to any one of [1] to [5], wherein the solubility of the third monomer in water at 20°C exceeds 230.0 g / L. [7] The adhesive composition according to [6], wherein the amount of the third constituent unit is 0.5% by mass or more and less than 5.0% by mass, based on the mass of all constituent units constituting the particulate polymer. [8] The solvent includes water, The adhesive composition according to any one of [1] to [7], wherein the amount of water is 80% by mass or more, based on the mass of the solvent. [9] It further contains a plasticizer, The adhesive composition according to any one of [1] to [8], wherein the plasticizer has a solubility in water at 20°C of 0.001 g / L or more and 10.0 g / L or less.

[10] The adhesive composition according to [9], wherein the amount of the plasticizer is 0.01% by mass or more and 10% by mass or less based on the mass of the particulate polymer.

[11] The adhesive composition according to any one of [1] to

[10] , wherein the amount of metal ions contained in the solvent is 0.0001% by mass or more and 2% by mass or less based on the mass of the solvent.

[12] Further comprising inorganic particles and a binder, The binder has a volume average particle diameter smaller than the volume average particle diameter of the particulate polymer in a state of pH 7.0, The adhesive composition according to any one of [1] to

[11] , wherein the binder has a glass transition temperature lower than the glass transition temperature of the particulate polymer.

[13] The volume average particle diameter of the particulate polymer is 1.0 μm or more, The adhesive composition according to any one of [1] to

[12] , wherein the glass transition temperature of the particulate polymer is 40°C or more.

[14] The adhesive composition according to any one of [1] to

[13] , further comprising a polymer soluble in the solvent.

[15] The adhesive composition according to any one of [1] to

[14] , further comprising a water-soluble preservative.

[16] The adhesive composition according to any one of [1] to

[15] , for use in the manufacture of a secondary battery.

[17] An electrode for a secondary battery, and An adhesive layer formed from the adhesive composition according to any one of [1] to

[16] , disposed on the electrode, and An adhesive electrode comprising the same.

[18] A separator for a secondary battery, and An adhesive layer formed from the adhesive composition according to any one of [1] to

[16] , disposed on the separator, and An adhesive separator comprising the same.

[19] Electrodes for secondary batteries, separators for secondary batteries, An adhesive layer formed from an adhesive composition according to any one of [1] to

[16] is disposed between the electrode and the separator, Rechargeable batteries, including those mentioned above. [Effects of the Invention]

[0008] The present invention can provide an adhesive composition with excellent stability. [Modes for carrying out the invention]

[0009] The embodiments of the present invention will be described in detail below, but the present invention is not limited to these, and various modifications are possible without departing from the spirit of the invention.

[0010] <Adhesive composition> One embodiment of the present invention is an adhesive composition comprising a particulate polymer, a radical scavenger, and a solvent, The particulate polymer comprises a first constituent unit derived from a first monomer, The solubility of the first monomer in water at 20°C is 20.0 g / L or more and 230.0 g / L or less. The amount of the first constituent unit is 10% by mass or more, based on the total mass of all constituent units constituting the particulate polymer. The solubility of the radical scavenger in water at 20°C is 0.1 g / L or more. The present invention relates to an adhesive composition in which the amount of the radical scavenger is 0.0001% by mass or more and 5% by mass or less, based on the mass of the particulate polymer.

[0011] The adhesive composition according to this embodiment exhibits excellent stability (particularly in terms of viscosity and cohesiveness). While the following reasons may explain this, the present invention is not limited in any way by these reasons. In other words, if the first monomer and radical generator used to form the particulate polymer remain in the adhesive composition, they are thought to separate from the particulate polymer, migrate to the solvent, and polymerize, generating by-products, changing the viscosity of the composition, and causing aggregates. However, by using a radical scavenger, the generation of by-products can be suppressed, thus improving stability.

[0012] [Particulate polymer] The adhesive composition contains particulate polymer.

[0013] (Volume-average particle size) The volume-average particle size of the particulate polymer is preferably 1.0 μm or larger, more preferably 1.4 μm to 15.0 μm, and even more preferably 2.0 μm to 5.0 μm. Having a volume-average particle diameter of 1.0 μm or more allows the particles to exhibit adhesive properties without being buried in inorganic particles. Because the volume-average particle diameter is 15.0 μm or less, the thickness after coating is suppressed, preventing the laminate with electrodes and other components from becoming excessively thick.

[0014] The volume-average particle size of particulate polymers can be increased by reducing the seed ratio to monomer during seed polymerization, thereby increasing the volume increase rate of individual particles. Conversely, the volume-average particle size of particulate polymers can be reduced by increasing the seed ratio, adding emulsifiers, and other means.

[0015] The volume-average particle size of particulate polymers can be measured by the method described in the examples below.

[0016] (Glass transition temperature) The glass transition temperature of the particulate polymer is preferably 40°C or higher, more preferably 50°C to 80°C, and even more preferably 55°C to 65°C. A glass transition temperature of 40°C or higher improves stability during storage. Adhesion is improved when the glass transition temperature is 80°C or lower.

[0017] The glass transition temperature of particulate polymers can be increased by increasing the proportion of monomers with relatively high Tg, such as styrene. The glass transition temperature of particulate polymers can be lowered by increasing the proportion of monomers with relatively low Tg, such as butyl acrylate.

[0018] The glass transition temperature of particulate polymers can be measured by the method described in the examples below.

[0019] (First constituent unit) The particulate polymer contains a first constituent unit derived from a first monomer.

[0020] The solubility of the first monomer in water at 20°C is 20.0 g / L or more and 230.0 g / L or less, preferably 40.0 g / L or more and 150.0 g / L or less, and more preferably 50.0 g / L or more and 90.0 g / L or less. When the solubility of the first monomer is 20.0 g / L or higher, the remaining monomer easily migrates to the solvent and by-products are formed, which is why the effects of the present invention are particularly easily exhibited. When the solubility of the first monomer is 230.0 g / L or less, particulate polymers tend to form more easily.

[0021] The first monomer is preferably non-crosslinkable or monofunctional.

[0022] Examples of the first monomer include vinyl cyanide monomer, carboxyl group-containing monomer, (meth)acrylamide monomer, and (meth)acrylic acid ester monomer.

[0023] More specific examples of the first monomer include ethyl acrylate, acrylonitrile, N-vinylpyrrolidone, vinyl acetate, and methacrylamide.

[0024] The first monomer may be a single type or a combination of two or more types.

[0025] The amount of the first constituent unit is 10% by mass or more, preferably 15% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 45% by mass or less, based on the total mass of all constituent units constituting the particulate polymer. The adhesion to the electrode is significantly improved when the amount of the first constituent unit is 10% by mass or more. The storage stability of the particulate polymer in water is improved by having the amount of the first constituent unit be 60% by mass or less.

[0026] (Second constituent unit) The particulate polymer may further contain a second constituent unit derived from the second monomer.

[0027] The second monomer is preferably a crosslinkable monomer copolymerizable with the first monomer. Including such a monomer tends to improve adhesive strength.

[0028] Examples of the second monomer include 3-(trimethoxysilyl)propyl methacrylate, divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, and ethylene glycol dimethacrylate.

[0029] The second monomer may be a single type or a combination of two or more types.

[0030] The amount of the second constituent unit is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.01% by mass or more and 3.0% by mass or less, and even more preferably 0.1% by mass or more and 1.0% by mass or less, based on the mass of all constituent units constituting the particulate polymer. By having a second constituent unit amount of 0.001% by mass or more, it is possible to suppress its dissolution and diffusion by the electrolyte inside the battery. By keeping the amount of the second constituent unit at 5% by mass or less, the particulate polymer can maintain high adhesiveness without becoming too hard.

[0031] (The third constituent unit) The particulate polymer may further contain a first constituent unit derived from a third monomer.

[0032] The solubility of the third monomer in water at 20°C is preferably 230.0 g / L or more, more preferably 300 g / L or more, and even more preferably 1000 g / L or more. The third monomer has a solubility of 230.0 g / L or higher, which allows for the imparting of hydrophilicity to the surface during copolymerization, thereby improving the storage stability of the particulate polymer.

[0033] The third monomer is preferably non-crosslinkable or monofunctional.

[0034] Examples of the third monomer include monomers having a carboxyl group such as methacrylic acid, acrylic acid, and itaconic acid; monomers having a hydroxyl group such as hydroxyethyl acrylate and hydroxyethyl methacrylate; monomers having a sulfonic acid such as sodium styrene sulfonic acid; monomers having a zwitterion such as 2-[[2-(methacryloyloxy)ethyl]dimethylammonio]acetic acid; and acrylamide.

[0035] The third monomer may be a single type or a combination of two or more types.

[0036] The amount of the third constituent unit is preferably 0.5% by mass or more and less than 5.0% by mass, more preferably 0.5% by mass or more and 2.0% by mass or less, and even more preferably 0.5% by mass or more and 1.0% by mass or less, based on the mass of all constituent units constituting the particulate polymer. Having a third constituent unit of 0.5% by mass or more results in a hydrophilic surface and improved storage stability of the particulate polymer. By having a third constituent unit amount of less than 5.0% by mass, the water solubility of the particulate polymer is reduced, making it easier to maintain the particle shape in the range of 1 μm or larger.

[0037] [Radical scavenger] The adhesive composition contains a radical scavenger. The use of a radical scavenger suppresses the generation of by-products from residual monomers.

[0038] The solubility of the radical scavenger in water at 20°C is 0.1 g / L or more, preferably 100 g / L or more, and more preferably 500 g / L or more. By having a solubility of 0.1 g / L or higher for the radical scavenger, radicals can be more effectively scavenged in the aqueous phase, improving the stability of the adhesive composition.

[0039] Examples of radical scavengers include oxoacid compounds, phenol compounds, quinone compounds, and polyvalent metal salt compounds.

[0040] Examples of oxoacid compounds include halogenated oxoacids (hypochlorous acid, chlorous acid, chloric acid, perchloric acid, hypobromous acid, bromous acid, bromate, perbromate, hypoiodic acid, iodic acid, iodic acid, periodic acid, etc.), boric acid, carbonic acid, orthocarbonic acid, carboxylic acid, silicic acid, nitrite, nitric acid, hypochlorous acid, hypophosphorous acid, phosphoric acid, arsenic acid, sulfite, sulfuric acid, sulfonic acid, sulfinic acid, chromic acid, dichromate, permanganic acid, tungstic acid, and their salts.

[0041] Examples of phenolic compounds include nitrophenol, p-methoxyphenol, phenothiazine, and dinitrobenzene.

[0042] Examples of quinone compounds include hydroquinone, p-benzoquinone, and t-butylhydroquinone.

[0043] Examples of polyvalent metal salt compounds include copper(II) chloride, copper(II) bis(dibutyldithiocarbamate), and iron(III) chloride.

[0044] Other radical scavengers include, for example, thiols such as N,N-diethylhydroxylamine and methyl mercaptan.

[0045] The radical scavenger may be a single type or a combination of two or more types.

[0046] The amount of radical scavenger is 0.0001% by mass or more and 5% by mass or less, preferably 0.01% by mass or more and 2% by mass or less, and more preferably 0.1% by mass or more and 1% by mass or less, based on the mass of the particulate polymer. By having a radical scavenging agent amount of 0.0001% by mass or more, radical reactions in the aqueous phase can be effectively suppressed. By keeping the amount of radical scavenger below 5% by mass, radicals inside the particles are less likely to be deactivated, thus suppressing the decrease in reaction rate.

[0047] [solvent] The adhesive composition contains a solvent.

[0048] The solvent preferably contains water.

[0049] The amount of water is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 99% by mass or more, based on the mass of the solvent.

[0050] The solvent may contain alcohol.

[0051] Examples of alcohols include methanol and ethanol.

[0052] The amount of alcohol is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.01% by mass or more and 1% by mass or less, based on the mass of the solvent. Having an alcohol content of 0.01% by mass or more results in suitable wettability when applied to a separator, improving the uniformity of the coating film. Because the alcohol content is 20% by mass or less, the dispersibility of the particles does not decrease, thus maintaining long-term dispersion stability.

[0053] The solvent can be just one type, or a combination of two or more types.

[0054] [Plasticizer] The adhesive composition may further contain a plasticizer.

[0055] The solubility of the plasticizer in water at 20°C is preferably 0.001 g / L or more and 10.0 g / L or less, more preferably 0.01 g / L or more and 5.0 g / L or less, and even more preferably 0.1 g / L or more and 1.0 g / L or less. Because the plasticizer has a solubility of 0.001 g / L or higher, the plasticizer is effectively incorporated into the particles via the aqueous phase, allowing it to be used without separation. By having a plasticizer solubility of 10.0 g / L or less, excessive leaching from the particles into the water is prevented, making it possible to effectively plasticize the particles.

[0056] Examples of plasticizers include diethyl adipate and dibutyl phthalate.

[0057] The plasticizer may be a single type or a combination of two or more types.

[0058] The amount of plasticizer is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5.0% by mass or less, and even more preferably 1.0% by mass or more and 3.0% by mass or less, based on the mass of the particulate polymer. By having a plasticizer amount of 0.01% by mass or more, it becomes possible to obtain a stable particle size distribution during the polymerization of particulate polymers. By limiting the amount of plasticizer to 10% by mass or less, it becomes possible to suppress excessive plasticization and the incorporation of copper particles.

[0059] [Inorganic particles] The adhesive composition may further contain inorganic particles.

[0060] The volume-average particle diameter of the inorganic particles is preferably 0.05 μm or more and 3.0 μm or less, more preferably 0.1 μm or more and 2.0 μm or less, and even more preferably 0.2 μm or more and 0.5 μm or less. Because the volume-average particle size of the inorganic particles is smaller than that of the particulate polymer, the probability of adhesive particles being exposed on the surface increases, and the contact area with the electrode increases, resulting in improved adhesion.

[0061] The volume-average particle size of inorganic particles can be measured by the method described in the examples below.

[0062] Examples of inorganic particles include boehmite, aluminum oxide, barium sulfate, and aluminum nitride.

[0063] The inorganic particles may consist of only one type, or a combination of two or more types.

[0064] The amount of inorganic particles is preferably 0% to 900% by mass, more preferably 40% to 300% by mass, and even more preferably 80% to 150% by mass, based on the mass of the particulate polymer. By keeping the amount of inorganic particles below 900% by mass, it is possible to significantly improve the heat resistance of the separator while maintaining adhesive properties.

[0065] [binder] The adhesive composition may further contain a binder.

[0066] The volume-average particle size of the binder is preferably smaller than that of the particulate polymer at a pH of 7.0. This allows for a greater number of binder particles than particulate polymer particles, enabling more effective adhesion.

[0067] The volume-average particle size of the binder can be measured by the method described in the examples below.

[0068] The glass transition temperature of the binder is preferably -60°C to 20°C, more preferably -40°C to 0°C, and even more preferably -35°C to -10°C.

[0069] The glass transition temperature of the binder can be measured by the method described in the examples below.

[0070] Examples of binders include acrylic latex binders and styrene-butadiene latex binders.

[0071] You may use only one type of binder, or a combination of two or more types.

[0072] The amount of binder is preferably 1% by mass or more and 10% by mass or less, more preferably 2% by mass or more and 7% by mass or less, and even more preferably 3% by mass or more and 5% by mass or less, based on the mass of the particulate polymer. Having a binder content of 1% by mass or more makes it possible to adhere the particulate polymer to the separator without causing it to fall off. By using a binder amount of 10% by mass or less, the amount of binder that clogs the separator pores after drying is reduced, thus minimizing the impact on battery resistance and enabling the creation of low-resistance batteries.

[0073] [Polymer] The adhesive composition may further contain a polymer that dissolves in the aforementioned solvent (hereinafter also referred to as "soluble polymer").

[0074] Examples of soluble polymers include polyacrylic acid and its salts, polyvinyl alcohol, polyvinylpyrrolidone, and carboxymethylcellulose and its salts.

[0075] The soluble polymer may be a single type or a combination of two or more types.

[0076] The amount of soluble polymer is preferably 0.1% by mass or more and 15.0% by mass or less, more preferably 0.5% by mass or more and 10.0% by mass or less, and even more preferably 1.0% by mass or more and 5.0% by mass or less, based on the mass of particulate polymer. Having a soluble polymer content of 0.1% by mass or more improves the stability of the particulate polymer, thereby suppressing aggregation due to sedimentation and improving redispersibility. By keeping the amount of soluble polymer to 15.0% by mass or less, the amount of polymer that clogs the separator pores after drying is reduced, thereby minimizing its impact on battery resistance and enabling the creation of low-resistance batteries.

[0077] [Water-soluble preservatives] The adhesive composition may further contain a water-soluble preservative.

[0078] A water-soluble preservative is a preservative that has a solubility of 10.0 g / L or more in water at 20°C.

[0079] Examples of water-soluble preservatives include 1,2-benzoisothiazol-3(2H)-one, methylisothiazolinone, and methylchloroisothiazolinone.

[0080] Water-soluble preservatives may be used individually or in combination of two or more types.

[0081] The amount of water-soluble preservative is preferably 0.0001% by mass or more and 1.0% by mass or less, more preferably 0.0003% by mass or more and 0.1% by mass or less, and even more preferably 0.001% by mass or more and 0.05% by mass or less, based on the total mass of the adhesive composition. By having a water-soluble preservative of 0.0001% by mass or more, the product can effectively suppress the growth of bacteria during long-term storage.

[0082] [Metal ions] The amount of metal ions contained in the solvent in the adhesive composition is preferably 0.0001% by mass or more and 2% by mass or less, more preferably 0.001% by mass or more and 1% by mass or less, and even more preferably 0.01% by mass or more and 0.1% by mass or less, based on the mass of the solvent. Having a metal ion content of 0.0001% by mass or more makes it possible to narrow the particle size distribution when manufacturing particles of 1 micrometer or larger. Having a metal ion content of 2% by mass or less improves the storage stability of the adhesive composition when it is stored.

[0083] Examples of metal ions include lithium ions, sodium ions, potassium ions, magnesium ions, calcium ions, and iron(II) ions.

[0084] The metal ion can be just one type, or a combination of two or more types.

[0085] [Application] The adhesive composition is preferably used to manufacture secondary batteries.

[0086] The adhesive composition is preferably used to form an adhesive layer placed on an electrode for a secondary battery.

[0087] The adhesive composition is preferably used to form an adhesive layer placed on a separator for secondary batteries.

[0088] The adhesive composition is preferably used to form an adhesive layer placed between the electrode for the secondary battery and the separator for the secondary battery.

[0089] <Adhesive electrodes, adhesive separators, and secondary batteries> One embodiment of the present invention relates to an adhesive electrode comprising an electrode for a secondary battery and an adhesive layer formed from the above-mentioned adhesive composition disposed on the electrode.

[0090] One embodiment of the present invention relates to an adhesive separator comprising a separator for a secondary battery and an adhesive layer formed from the above-mentioned adhesive composition disposed on the separator.

[0091] One embodiment of the present invention relates to a secondary battery comprising an electrode for a secondary battery, a separator for a secondary battery, and an adhesive layer formed from the above-mentioned adhesive composition disposed between the electrode and the separator.

[0092] The types of electrodes used for secondary batteries are not particularly limited; they can be any type commonly used as electrodes for secondary batteries.

[0093] The types of separators used for secondary batteries are not particularly limited; they can be any type commonly used as separators for secondary batteries.

[0094] The method for forming the adhesive layer is not particularly limited. For example, one method is to apply the adhesive composition to the electrodes and / or separators for secondary batteries. [Examples]

[0095] The present invention will be described in more detail below using examples and comparative examples, but the technical scope of the present invention is not limited thereto.

[0096] The various values ​​in the examples may be preferred lower or upper limits in the embodiments of the present invention. Alternatively, two similar values ​​in the examples may be combined as appropriate to form a preferred numerical range.

[0097] The various measurements and evaluations in this embodiment were performed as follows.

[0098] [Test Example 1: Measurement of Glass Transition Temperature] An appropriate amount of an aqueous dispersion containing particulate polymer or binder was placed in an aluminum dish and dried in a hot air dryer at 130°C for 1 hour. Approximately 10 mg of the dried film was placed in an aluminum container for measurement, and DSC and DDSC curves were obtained under a nitrogen atmosphere using a DSC measuring device (Shimadzu Corporation, model number: DSC6220). The glass transition temperature was determined from the obtained DSC and DDSC curves.

[0099] [Test Example 2: Measurement of Volume-Average Particle Diameter] Using a light scattering particle size analyzer (LEED & NORTHRUP, product name "MICROTRAC UPA150"), the 50% particle size (nm) of particulate polymers, inorganic particles, or binders was measured based on volume and defined as the volume-average particle diameter.

[0100] [Test Example 3: Evaluation of Viscosity Retention Rate of Adhesive Compositions] After stirring and dispersing the adhesive composition, the initial viscosity (η0) immediately after preparation and the post-storage viscosity (η100) after storing the adhesive composition in a sealed state at a storage temperature of 50°C for 25 days were measured using an E-type viscometer. Note that the 25-day storage at 50°C may be performed as an accelerated test equivalent to 100 days of storage at room temperature.

[0101] The viscosity retention rate was calculated using the following formula. "Abs(η100 / η0)" is the absolute value of the viscosity after storage divided by the initial viscosity. A low viscosity retention rate indicates that the quality has deteriorated. Viscosity maintenance rate (%)=[Abs(η100 / η0)]×100

[0102] (Viscosity measurement conditions) Measuring device: Manufactured by Toki Sangyo, model name "TVE-33H" Cone rotor type: 1°34'×R24 Paste input amount: approximately 1 mL Shear speed: 21.5S-1 Measurement temperature: 20℃

[0103] (Evaluation Criteria) A: Viscosity maintenance rate 99.5% or more B: Viscosity retention rate 99.0% or higher and less than 99.5% C: Viscosity retention rate 98.0% or higher and less than 99.0% D: Viscosity retention rate less than 98.0%

[0104] [Test Example 4: Evaluation of Aggregation Stability of Adhesive Compositions (Mechanical Stability Evaluation)] Using a Marlon-type test apparatus, the amount of aggregates generated was evaluated when a shear force of 10 kg and a rotation speed of 1000 rpm was applied to 50 g of an adhesive composition with a solid content concentration of 20% by mass for 10 minutes. Specifically, after applying a shear force under the above conditions, the aggregates adhering to the rotor portion of the Marlon-type test apparatus were collected on a SUS80 mesh wire screen, washed with pure water, dried under reduced pressure, and then their mass was measured. The aggregate formation rate was calculated from the measured dried mass of the aggregates using the following formula, and this was used as an indicator of mechanical stability. A smaller aggregate formation rate indicates greater stability against shear force and higher mechanical stability. Aggregate generation rate (%) = [Dry mass of aggregates (g) / Solid content mass of adhesive composition (g)] × 100

[0105] (Evaluation Criteria) A: Aggregate generation rate less than 0.3% B: Aggregate generation rate less than 0.5% or more than 0.3% C: Aggregate generation rate less than 1.0% or more than 0.5% D: Aggregate generation rate of 1.0% or higher

[0106] [Test Example 5: Evaluation of Adhesion of Adhesive Compositions] The separators or electrodes equipped with adhesive layers, prepared in the examples and comparative examples described later, were cut into rectangles measuring 1 cm wide x 7 cm long to prepare test specimens. Uncoated separators were placed opposite these test specimens and placed under pressure at 45°C, 1.0 MPa, and 2 minutes to prepare samples. The stress was measured when one end of the uncoated separator was pulled vertically upward at a tensile speed of 100 mm / min to peel it off. This measurement was performed five times, and the average stress value was determined as the peel strength. A higher peel strength indicates better adhesion.

[0107] (Evaluation Criteria) A: Peel strength of 4.0 N / m or more B: Peel strength 0.5 N / m or more and less than 4.0 N / m C: Peel strength 0.1 N / m or more and less than 0.5 N / m D: Peel strength less than 0.1 N / m

[0108] [Abbreviation] The abbreviation has the following meanings. • EA: Ethyl acrylate • MAAm: Methacrylamide AN: Acrylonitrile • γ-MPS: 3-(trimethoxysilyl)propyl methacrylate • EGDMA: Ethylene glycol dimethacrylate • MAA: Methacrylic acid • AAm: Acrylamide 2-EHA: 2-ethylhexyl acrylate BA: Butyl acrylate St: Styrene PBO: Perbutyl Oxide APS: Ammonium persulfate • DBP: Dibutylphthalate BIT: 1,2-benzoisothiazole-3(2H)-one • PAA-Na: Sodium polyacrylate salt • CMC-Na: Sodium salt of carboxymethylcellulose • PVA: Polyvinyl alcohol • ACL-Ltx: Acrylic latex binder

[0109] [Example 1] (Manufacturing of particulate polymers) In a reactor equipped with a stirrer, 100 parts by mass of deionized water, 2.0 parts by mass of ammonium persulfate as a radical polymerization initiator, and 0.05 parts by mass of sodium chloride were added. The gas phase in the reactor was then replaced with nitrogen gas, and the temperature was raised to 70°C.

[0110] Emulsified solution 1 was prepared by mixing 100 parts by mass of deionized water, 0.1 parts by mass of sodium lauryl sulfate, 12 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of ethyl acrylate, 50 parts by mass of styrene, 2 parts by mass of methacrylic acid, 20 parts by mass of acrylonitrile, and 1 part by mass of γ-MPS in a separate container equipped with a stirrer.

[0111] Emulsion 1 was continuously added to the reactor over 2.0 hours while continuously stirring to initiate the reaction. After the addition of emulsification 1 was complete, the reaction was further stirred at 80°C for 2.0 hours to complete, yielding an aqueous dispersion containing particulate polymer 1. The monomer reaction rate at the end of the reaction was 99%.

[0112] When the glass transition temperature (Tg) of the particulate polymer was measured using Test Example 1 above, the observed glass transition temperature (Tg) was +57°C at only one point. In addition, the volume-average particle size of the particulate polymer measured using Test Example 2 above was 420 nm.

[0113] (Manufacturing of adhesive compositions) 100.0 parts by mass of particulate polymer (equivalent to solid content), 0.05 parts by mass of diethyl adipate as a plasticizer, 3.0 parts by mass of acrylic latex (Acl-Ltx) (BA / MMA / MAA copolymer latex, average particle size: 120 nm, Tg: -35℃) as a particulate binder, 0.5 parts by mass of SN Wet 126 (manufactured by Sunopco), a water-soluble silicone-based surfactant, as a wetting agent, 0.5 parts by mass of sodium nitrite as a radical scavenger, and 300 ppm of BIT (1,2-benzoisothiazolin-3-one) as a preservative per 100 parts by mass of solid content were added. Finally, an amount of deionized water was added to bring the solid content concentration to 30%. After passing through a magnetic separator, the mixture was filtered through a #200 mesh filter. This yielded particulate polymer dispersion 1.

[0114] To 100 parts by mass of deionized water, 300 parts by mass of boehmite powder (particle size 0.2 μm) was added as inorganic particles, and 4 parts by mass of polyammonium carboxylate salt (Sunopco, Nopcospers 5600) equivalent to solid content was added as a dispersant. The mixture was then subjected to ultrasonic irradiation for 30 minutes while cooling in an ultrasonic dispersion device. After adding 3.0 parts by mass of acrylic latex (Acl-Ltx) (BA / MMA / MAA copolymer latex, average particle size: 120 nm, Tg: -35℃) as a particulate binder, the mixture was passed through a magnetic separator and filtered through a #200 mesh filter to obtain an inorganic particle dispersion.

[0115] An adhesive composition was obtained by mixing a particulate polymer dispersion with an inorganic particle dispersion in a mass ratio of 1:9, adding 1.0 part by mass of sodium polyacrylate as a viscosity modifier, and finally adding methanol in an amount of 0.01 parts by mass per 100 parts by mass of solvent. The viscosity retention rate and cohesive stability (mechanical stability) of the adhesive composition were evaluated according to the above Test Examples 3 and 4.

[0116] (Separator manufacturing) A separator substrate made of a porous polyethylene substrate was prepared. The adhesive composition was prepared with a basis weight of 2.5 g / m². 2The adhesive was applied to one side of the separator substrate and dried with hot air for 10 minutes. This created a separator with an adhesive layer. The adhesive strength of the separator was evaluated according to Test Example 5 above.

[0117] [Example 2] (Manufacturing of particulate polymers) In a reactor equipped with a stirrer, 100 parts by mass of deionized water, 3 parts by mass of particulate polymer 1 prepared in Example 1 as seed particles (solid content), 1.0 part by mass of ammonium persulfate as a radical polymerization initiator, and 0.05 parts by mass of sodium chloride were added. The gas phase in the reactor was replaced with nitrogen gas, and the temperature was raised to 70°C.

[0118] Emulsified solution 2 was prepared by adding 100 parts by mass of deionized water, 0.05 parts by mass of sodium lauryl sulfate, 12 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of ethyl acrylate, 50 parts by mass of styrene, 2 parts by mass of methacrylic acid, 20 parts by mass of acrylonitrile, and 1 part by mass of γ-MPS to a separate container equipped with a stirrer and stirring.

[0119] For every 3 parts by mass of solids of particulate polymer 1, 97 parts by mass of emulsion 2 were used. The emulsion 2 was continuously added to the reactor over 2.0 hours while stirring to initiate the reaction. After the addition of emulsion 2 was completed, the reaction was further stirred at 80°C for 2.0 hours to complete the reaction and obtain an aqueous dispersion containing particulate polymer 2. The monomer reaction rate at the end of the reaction was 99%.

[0120] When the glass transition temperature (Tg) of particulate polymer 2 was measured using Test Example 1 above, the observed glass transition temperature (Tg) was +57°C at only one point. Furthermore, the volume-average particle size of particulate polymer 2 measured using Test Example 2 above was 1050 nm.

[0121] (Manufacturing of adhesive compositions and separators) An adhesive composition and a separator were prepared and evaluated using the same method as in Example 1, except that the viscosity modifier was 2.0 parts by mass of polyvinyl alcohol.

[0122] [Example 3] (Manufacturing of particulate polymers) 100 parts by mass of deionized water and 0.05 parts by mass of sodium chloride were added to a reactor equipped with a stirrer, the gas phase in the reactor was replaced with nitrogen gas, and the temperature was raised to 70°C.

[0123] In a separate container equipped with a stirrer, 100 parts by mass of deionized water, 0.05 parts by mass of sodium lauryl sulfate, 6.0 parts by mass of sodium polyacrylate, 12 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of ethyl acrylate, 50 parts by mass of styrene, 2 parts by mass of methacrylic acid, 20 parts by mass of acrylonitrile, 1 part by mass of γ-MPS, and 2 parts by mass of perbutyl O were added and stirred using a homodisper to prepare suspension A.

[0124] The entirety of suspension A was added to the reactor while continuing to stir, and then 0.5 parts by mass of sodium nitrite was added as a radical scavenger to start the reaction. The reaction was completed by stirring at 70°C for 7.0 hours to obtain an aqueous dispersion containing particulate polymer. The monomer reaction rate at the end of the reaction was 99%.

[0125] When the glass transition temperature (Tg) of the particulate polymer was measured using Test Example 1 above, the observed glass transition temperature (Tg) was +57°C at only one point. Furthermore, the volume-average particle size of the particulate polymer measured using Test Example 2 above was 1500 nm.

[0126] (Manufacturing of adhesive compositions and separators) Except for not using a radical scavenger in the production of the adhesive composition (the radical scavenger is used in the production process of particulate polymers), the adhesive composition and separator were produced and evaluated in the same manner as in Example 1.

[0127] [Examples 4, 14-17, 23, 24] Except for changing the monomers constituting the particulate polymer, the particulate polymer, adhesive composition, and separator were manufactured and evaluated in the same manner as in Example 3.

[0128] [Examples 5 and 6] Except for changing the amount of radical scavenger, particulate polymers, adhesive compositions, and separators were manufactured and evaluated in the same manner as in Example 3.

[0129] [Examples 7-13] Except for changing the type of radical scavenger, particulate polymers, adhesive compositions, and separators were manufactured and evaluated using the same method as in Example 3.

[0130] [Examples 18 and 19] Except for changing the amount of plasticizer, particulate polymers, adhesive compositions, and separators were manufactured and evaluated using the same method as in Example 3.

[0131] [Example 20] Except for changing the type and amount of plasticizer, particulate polymers, adhesive compositions, and separators were manufactured and evaluated using the same method as in Example 3.

[0132] [Example 21] Except for changing the amount of sodium chloride, particulate polymers, adhesive compositions, and separators were manufactured and evaluated in the same manner as in Example 3.

[0133] [Example 22] Except for not using inorganic particles, particulate polymers, adhesive compositions, and separators were manufactured and evaluated using the same method as in Example 3.

[0134] [Example 25] Except for changing the type and amount of water-soluble polymer, particulate polymers, adhesive compositions, and separators were manufactured and evaluated using the same method as in Example 3.

[0135] [Example 26] (Manufacturing of particulate polymers and adhesive compositions) Particulate polymers and adhesive compositions were prepared using the same method as in Example 3.

[0136] (Electrode manufacturing) A negative electrode was prepared by coating copper foil with a slurry containing a graphite-based active material. The adhesive composition had a basis weight of 3.0 g / m². 2 To achieve this, the material was applied to the negative electrode, and the electrode was dried with hot air for 10 minutes to create an electrode with an adhesive layer. The adhesive strength of the electrode was evaluated according to Test Example 5 described above.

[0137] [Comparative Examples 1 and 2] Except for changing the amount of radical scavenger, particulate polymers, adhesive compositions, and separators were manufactured and evaluated in the same manner as in Example 3.

[0138] [Comparative Example 3] Except for changing the monomers constituting the particulate polymer, particulate polymers, adhesive compositions, and separators were manufactured and evaluated in the same manner as in Example 1.

[0139] [Comparative Example 4] In a reactor equipped with a stirrer, 100 parts by mass of deionized water, 4.0 parts by mass of ammonium persulfate as a radical polymerization initiator, and 0.05 parts by mass of sodium chloride were added. The gas phase in the reactor was then replaced with nitrogen gas, and the temperature was raised to 70°C.

[0140] In a separate container equipped with a stirrer, 100 parts by mass of deionized water, 0.1 parts by mass of sodium lauryl sulfate as an emulsifier, 80 parts by mass of methacrylic acid, and 20 parts by mass of acrylamide were added and stirred to prepare a solution.

[0141] This solution was continuously added to the reactor over 2.0 hours while stirring to initiate the reaction. After the addition of the solution was complete, the reaction was further stirred at 80°C for 2.0 hours to terminate the reaction. No particles were obtained, and a translucent, viscous liquid was acquired. The monomer reaction rate at the end of the reaction was 91%.

[0142] Table 1-1 Table 1-2 Table 1-3

Claims

1. A particulate polymer, a radical scavenger, and a solvent. An adhesive composition comprising, The particulate polymer comprises a first constituent unit derived from a first monomer, The solubility of the first monomer in water at 20°C is 20.0 g / L or more and 230.0 g / L or less. The amount of the first constituent unit is 10% by mass or more, based on the total mass of all constituent units constituting the particulate polymer. The solubility of the radical scavenger in water at 20°C is 0.1 g / L or more. An adhesive composition in which the amount of the radical scavenger is 0.0001% by mass or more and 5% by mass or less, based on the mass of the particulate polymer.

2. The radical scavenger comprises at least one selected from the group consisting of oxoacid compounds, phenol compounds, quinone compounds, and polyvalent metal salt compounds. The adhesive composition according to claim 1.

3. The first monomer comprises at least one selected from the group consisting of vinyl cyanide monomer, carboxyl group-containing monomer, (meth)acrylamide monomer, and (meth)acrylic acid ester monomer. The adhesive composition according to claim 1.

4. The particulate polymer further comprises a second constituent unit derived from a second monomer, The second monomer is a crosslinkable monomer that can copolymerize with the first monomer. The adhesive composition according to claim 1.

5. The amount of the second constituent unit is 0.001% by mass or more and 5% by mass or less, based on the total mass of all constituent units constituting the particulate polymer. The adhesive composition according to claim 4.

6. The particulate polymer further comprises a third constituent unit derived from a third monomer, The solubility of the third monomer in water at 20°C is greater than 230.0 g / L. The adhesive composition according to claim 1.

7. The amount of the third constituent unit is 0.5% by mass or more and less than 5.0% by mass, based on the total mass of all constituent units constituting the particulate polymer. The adhesive composition according to claim 6.

8. The solvent includes water, The adhesive composition according to claim 1, wherein the amount of water is 80% by mass or more, based on the mass of the solvent.

9. It further contains a plasticizer, The adhesive composition according to claim 1, wherein the plasticizer has a solubility in water at 20°C of 0.001 g / L or more and 10.0 g / L or less.

10. The amount of the plasticizer is 0.01% by mass or more and 10% by mass or less, based on the mass of the particulate polymer. The adhesive composition according to claim 9.

11. The amount of metal ions contained in the solvent is 0.0001% by mass or more and 2% by mass or less, based on the mass of the solvent. The adhesive composition according to claim 1.

12. It further comprises inorganic particles and a binder, The binder has a volume-average particle diameter smaller than the volume-average particle diameter of the particulate polymer at a pH of 7.

0. The binder has a glass transition temperature lower than the glass transition temperature of the particulate polymer. The adhesive composition according to claim 1.

13. The volume-average particle diameter of the particulate polymer is 1.0 μm or more. The glass transition temperature of the particulate polymer is 40°C or higher. The adhesive composition according to claim 1.

14. The solvent further comprises a polymer that dissolves in the aforementioned solvent. The adhesive composition according to claim 1.

15. It also contains a water-soluble preservative. The adhesive composition according to claim 1.

16. For use in the manufacture of secondary batteries, The adhesive composition according to claim 1.

17. Electrodes for secondary batteries, An adhesive layer formed from the adhesive composition according to any one of claims 1 to 16, disposed on the electrode, Adhesive electrodes, including those mentioned above.

18. A separator for secondary batteries, An adhesive layer formed from the adhesive composition according to any one of claims 1 to 16, disposed on the separator, Adhesive separators, including [specific component].

19. Electrodes for secondary batteries, separators for secondary batteries, An adhesive layer formed from the adhesive composition according to any one of claims 1 to 16 is disposed between the electrode and the separator, Rechargeable batteries, including those mentioned above.

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