Binder composition for non-aqueous secondary battery functional layer, slurry composition for non-aqueous secondary battery functional layer, separator for non-aqueous secondary battery, electrode for non-aqueous secondary battery, and non-aqueous secondary battery

Abstract

The purpose of the present invention is to provide a binder composition for a functional layer of a non-aqueous secondary battery, said binder composition having excellent dispersion stability and being capable of forming a functional layer capable of improving high-temperature storage characteristics of a secondary battery. This binder composition for a non-aqueous secondary battery functional layer is characterized by containing a particulate polymer A, a particulate polymer B different from the particulate polymer A, and a dispersion medium. The adhesive composition for a non-aqueous secondary battery functional layer has a coating film obtained by coating and drying a polyethylene separator base material with the adhesive composition, the 86 DEG glossiness of the coating film being 1-70, and the 60 DEG glossiness of the coating film being less than 6.

Description

Technical Field

[0001] The present invention relates to an adhesive composition for a non-aqueous secondary battery functional layer, a slurry composition for a non-aqueous secondary battery functional layer, a separator for a non-aqueous secondary battery, an electrode for a non-aqueous secondary battery, and a non-aqueous secondary battery. Background Art

[0002] Non-aqueous secondary batteries (hereinafter sometimes simply referred to as "secondary batteries"), such as lithium-ion secondary batteries, are compact, lightweight, have high energy density, and are capable of repeated charge and discharge, making them used in a wide range of applications. Furthermore, non-aqueous secondary batteries generally have battery components such as a positive electrode, a negative electrode, and a separator that separates the positive and negative electrodes to prevent short circuits between them.

[0003] Here, in the secondary battery, a battery component having a functional layer of a desired performance (such as heat resistance, strength, etc.) imparted to the battery component is used. Specifically, as a battery component, a spacer such as a spacer forming a functional layer on a spacer substrate, an electrode forming a functional layer on an electrode substrate in which an electrode composite material layer is arranged on a current collector is used. In addition, as a functional layer capable of improving the heat resistance, strength, etc. of the battery component, a functional layer consisting of a porous film layer formed by bonding non-conductive particles with a binder (binder) is used. Moreover, such a functional layer can be formed, for example, by the following method: a slurry composition (slurry composition for functional layer) in which components such as non-conductive particles and a composition comprising a binder (binder composition for functional layer) are dissolved or dispersed in a solvent is applied to the surface of a substrate (spacer substrate, electrode substrate, etc.), and the applied slurry composition is dried.

[0004] Furthermore, in recent years, with the aim of achieving further enhanced performance of secondary batteries, improvements in binder compositions and slurry compositions for forming functional layers have been actively pursued.

[0005] For example, Patent Document 1 proposes an electrochemical element slurry composition comprising a granular polymer having a specified core-shell structure, a binder, and heat-resistant fine particles, wherein the electrolyte contact angle of the granular polymer is set to be between 0° and 35°, and the volume average particle size of the granular polymer is set to be between 1.0 μm and 10.0 μm. Furthermore, Patent Document 1 states that the functional layer obtained using the electrochemical element slurry composition can improve the electrolyte injection and storage characteristics of electrochemical elements such as lithium-ion secondary batteries, while also exhibiting excellent adhesion (process adhesion) during the manufacturing process of the electrochemical element.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent document 1: International Publication No. 2022 / 124126. Summary of the Invention

[0009] Problems to be solved by the invention

[0010] Here, the functional layer adhesive composition and the functional layer slurry composition are required to suppress the aggregation and sedimentation of the components in the composition (i.e., the reduction of dispersion stability). However, the above-mentioned prior art still has room for improvement in suppressing the reduction of dispersion stability of the functional layer adhesive composition and the functional layer slurry composition.

[0011] Furthermore, secondary batteries having functional layers formed using a functional layer binder composition and a functional layer slurry composition are generally required to have excellent battery characteristics such as high-temperature storage properties. However, secondary batteries having functional layers formed using the conventional functional layer slurry composition do not have sufficient high-temperature storage properties.

[0012] Solutions for solving problems

[0013] Therefore, an object of the present invention is to provide a binder composition for a non-aqueous secondary battery functional layer that has excellent dispersion stability and can form a functional layer that can improve the high-temperature storage characteristics of the secondary battery.

[0014] Another object of the present invention is to provide a slurry composition for a non-aqueous secondary battery functional layer, which can form a functional layer capable of improving the high-temperature storage characteristics of a secondary battery.

[0015] Another object of the present invention is to provide a separator for a non-aqueous secondary battery and an electrode for a non-aqueous secondary battery capable of improving the high-temperature storage characteristics of a secondary battery.

[0016] Furthermore, an object of the present invention is to provide a non-aqueous secondary battery having excellent high-temperature storage characteristics.

[0017] The present inventors conducted intensive research with the goal of resolving the above-mentioned problems. They recently discovered that when a non-aqueous binder composition for a secondary battery functional layer comprising two particulate polymers and a dispersion medium is applied to a specified separator substrate and dried to form a coating film, if the 86° gloss and 60° gloss of the coating film are within specified ranges, the binder composition for the secondary battery functional layer exhibits excellent dispersion stability and enables a secondary battery having a functional layer formed using the non-aqueous binder composition to exhibit excellent high-temperature storage characteristics. This discovery led to the completion of the present invention.

[0018] That is, the present invention aims to advantageously solve the above-mentioned problems. The present invention provides [1] a binder composition for a non-aqueous secondary battery functional layer, comprising a particulate polymer A, a particulate polymer B different from the particulate polymer A, and a dispersion medium, wherein the binder composition for a non-aqueous secondary battery functional layer is applied to a polyethylene separator substrate and dried to obtain a coating film, wherein the 86° glossiness of the coating film is 1 or more and 70 or less, and the 60° glossiness is less than 6. If the 86° glossiness and 60° glossiness of the coating film obtained by applying and drying the coating film on a predetermined separator substrate are respectively within the above-mentioned specified ranges, the binder composition for a secondary battery functional layer has excellent dispersion stability, and a secondary battery having a functional layer formed using the binder composition for a secondary battery functional layer can exhibit excellent high-temperature storage characteristics.

[0019] In the present invention, the 86° glossiness and 60° glossiness of a coating film obtained by applying and drying the binder composition for a non-aqueous secondary battery functional layer on a polyethylene separator substrate can be measured by the methods described in Examples.

[0020] [2] In the binder composition for a non-aqueous secondary battery functional layer of the above-mentioned [1], the coating film preferably has a ratio of 86° glossiness to 60° glossiness (86° glossiness / 60° glossiness) of 1 or more and 50 or less. Thus, if the ratio of 86° glossiness to 60° glossiness of the coating film is within the above-mentioned prescribed range, the dispersion stability of the binder composition for a non-aqueous secondary battery functional layer can be further improved, and the high-temperature storage characteristics of the secondary battery can be further improved.

[0021] [3] In the binder composition for the non-aqueous secondary battery functional layer of the above-mentioned [1] or [2], it is preferred that the dispersion medium is water, and the pH of the binder composition for the non-aqueous secondary battery functional layer is greater than 7.5 and less than 9.0. In this way, if the dispersion medium of the binder composition for the non-aqueous secondary battery functional layer is water and the pH of the binder composition for the non-aqueous secondary battery functional layer is greater than the above-mentioned lower limit, the stability of the binder composition for the non-aqueous secondary battery functional layer or the non-aqueous secondary battery functional layer slurry composition prepared using the binder composition for the non-aqueous secondary battery functional layer can be improved when applied to a substrate. In addition, by making the pH of the binder composition less than the above-mentioned upper limit, the adhesion of the functional layer before immersion in the electrolyte (hereinafter, sometimes simply referred to as "dry adhesion") and the adhesion after immersion in the electrolyte (hereinafter, sometimes simply referred to as "wet adhesion") can be improved.

[0022] The pH of the binder composition for a non-aqueous secondary battery functional layer can be measured by the method described in Examples.

[0023] [4] In the binder composition for a non-aqueous secondary battery functional layer according to any one of [1] to [3], the mass ratio of the particulate polymer A to the particulate polymer B (particulate polymer A:particulate polymer B) is preferably 50:50 or greater and 95:5 or less. When the mass ratio of the particulate polymer A to the particulate polymer B is within the above-specified range, powdering (shedding of the particulate polymer) of the functional layer can be suppressed, improving both the dry and wet adhesive properties of the functional layer, and further enhancing the high-temperature storage characteristics of the secondary battery.

[0024] [5] In the binder composition for a non-aqueous secondary battery functional layer according to any one of [1] to [4], the volume average particle size D50 of the particulate polymer A is preferably 0.5 μm or more and 10 μm or less. If the volume average particle size D50 of the particulate polymer A is within the above-specified range, the dry adhesiveness and wet adhesiveness of the functional layer can be improved.

[0025] In the present invention, the volume average particle diameter D50 of the particulate polymer A can be measured by the method described in Examples.

[0026] [6] In the binder composition for a non-aqueous secondary battery functional layer according to any one of [1] to [5], the electrolyte swelling degree of the particulate polymer A is preferably 1 to 5 times. If the electrolyte swelling degree of the particulate polymer A is within the above-specified range, the high-temperature storage characteristics of the secondary battery can be further improved.

[0027] In the present invention, the degree of swelling of the particulate polymer with the electrolyte solution can be measured by the method described in Examples.

[0028] [7] In the binder composition for a non-aqueous secondary battery functional layer according to any one of [1] to [6], the particulate polymer A preferably contains 25% by mass or more of aromatic vinyl monomer units. When the particulate polymer A contains aromatic vinyl monomer units in a ratio not less than the above lower limit, the elasticity of the particulate polymer A is improved, and the strength of the resulting functional layer can be ensured. As a result, the adhesion between the functional layer and the substrate (separator substrate, electrode substrate) can be improved.

[0029] In the present invention, the polymer "contains monomer units" means "a polymer obtained using the monomer contains structural units derived from the monomer." In the present invention, the ratio of monomer units in the polymer can be expressed as 1 The determination was performed using nuclear magnetic resonance (NMR) methods such as H-NMR.

[0030] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. The present invention is [8] a slurry composition for a non-aqueous secondary battery functional layer, comprising inorganic particles and a binder composition for a non-aqueous secondary battery functional layer according to any one of [1] to [7]. A slurry composition for a non-aqueous secondary battery functional layer comprising inorganic particles and any one of the binder compositions for a non-aqueous secondary battery functional layer can form a functional layer that can improve the high-temperature storage characteristics of a secondary battery. Furthermore, the use of this slurry composition can improve the heat resistance of the functional layer.

[0031] [9] In the slurry composition for a non-aqueous secondary battery functional layer of [8], the volume average particle size D50 of the inorganic particles is preferably 0.1 μm or more and 1.0 μm or less. As such, if the volume average particle size D50 of the inorganic particles is within the above-specified range, the secondary battery can exhibit excellent battery characteristics (especially output characteristics), and even when the functional layer is thinned, the battery components (separators, electrodes) having the functional layer can fully exhibit heat shrinkage resistance.

[0032] In the present invention, the volume average particle diameter D50 of the inorganic particles can be measured by the method described in Examples in the same manner as the volume average particle diameter D50 of the particulate polymer A.

[0033] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. The present invention is

[10] a separator for a non-aqueous secondary battery, comprising a separator substrate and a functional layer provided on at least one surface of the separator substrate, wherein the functional layer is formed using the binder composition for a non-aqueous secondary battery functional layer of any one of [1] to [7] or the slurry composition for a non-aqueous secondary battery functional layer of [8] or [9]. Thus, a separator for a non-aqueous secondary battery having a functional layer formed using the binder composition for a non-aqueous secondary battery functional layer or the slurry composition for a non-aqueous secondary battery functional layer can enable a secondary battery to exhibit excellent high-temperature storage characteristics.

[0034] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. The present invention is

[11] a non-aqueous secondary battery electrode comprising an electrode substrate and a functional layer provided on at least one surface of the electrode substrate, wherein the functional layer is formed using the binder composition for a non-aqueous secondary battery functional layer of any one of [1] to [7] or the slurry composition for a non-aqueous secondary battery functional layer of [8] or [9]. Thus, the non-aqueous secondary battery electrode having a functional layer formed using the binder composition for a non-aqueous secondary battery functional layer or the slurry composition for a non-aqueous secondary battery functional layer can enable the secondary battery to exhibit excellent high-temperature storage characteristics.

[0035] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. The present invention is

[12] a non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the separator is the non-aqueous secondary battery separator of

[10] . As described above, the non-aqueous secondary battery having the non-aqueous secondary battery separator has excellent high-temperature storage characteristics.

[0036] Furthermore, the present invention aims to advantageously solve the above-mentioned problems. The present invention is

[13] a non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein at least one of the positive electrode and the negative electrode is the non-aqueous secondary battery electrode of

[11] . As such, the non-aqueous secondary battery comprising the non-aqueous secondary battery electrode has excellent high-temperature storage characteristics.

[0037] Effects of the Invention

[0038] According to the present invention, a binder composition for a non-aqueous secondary battery functional layer can be provided which has excellent dispersion stability and can form a functional layer capable of improving the high-temperature storage characteristics of a secondary battery.

[0039] Furthermore, according to the present invention, it is possible to provide a slurry composition for a non-aqueous secondary battery functional layer capable of forming a functional layer capable of improving the high-temperature storage characteristics of a secondary battery.

[0040] Furthermore, according to the present invention, a separator for a non-aqueous secondary battery and an electrode for a non-aqueous secondary battery capable of improving the high-temperature storage characteristics of a secondary battery can be provided.

[0041] Furthermore, according to the present invention, a non-aqueous secondary battery having excellent high-temperature storage characteristics can be provided. DETAILED DESCRIPTION

[0042] Hereinafter, embodiments of the present invention will be described in detail.

[0043] The binder composition for the functional layer of a non-aqueous secondary battery of the present invention (hereinafter, sometimes referred to as simply "the binder composition") can be used to manufacture a non-aqueous secondary battery, and can be preferably used in, for example, the preparation of a slurry composition for the functional layer of a non-aqueous secondary battery of the present invention. In addition, the binder composition for the functional layer of a non-aqueous secondary battery of the present invention can also be used to form a functional layer that has the function of bonding a separator substrate and an electrode substrate by, for example, applying and drying on a separator substrate and an electrode substrate. The slurry composition for the functional layer of a non-aqueous secondary battery of the present invention (hereinafter, sometimes referred to as simply "the slurry composition") can be used to form a functional layer that has the function of bonding a separator substrate and an electrode substrate, and reinforcing the same by, for example, applying and drying on a separator substrate and an electrode substrate, and can be preferably used in the manufacture of a separator for a non-aqueous secondary battery of the present invention (hereinafter, sometimes referred to as simply "the separator") and a non-aqueous secondary battery electrode of the present invention (hereinafter, sometimes referred to as simply "the electrode"). Furthermore, the separator for a non-aqueous secondary battery and the electrode for a non-aqueous secondary battery of the present invention can be preferably used when producing the non-aqueous secondary battery of the present invention, such as a lithium ion secondary battery, for example.

[0044] In addition, in this specification, "separator substrate" and "electrode substrate" may be simply referred to as "substrate".

[0045] (Binder composition for non-aqueous secondary battery functional layer)

[0046] The adhesive composition of the present invention comprises a particulate polymer A, a particulate polymer B different from the particulate polymer A, and a dispersion medium, and may optionally further comprise other components.

[0047] Furthermore, the adhesive composition for a non-aqueous secondary battery functional layer of the present invention is characterized in that, when applied and dried onto a polyethylene separator substrate, the resulting coating film has an 86° gloss of 1 or higher and 70 or lower, and a 60° gloss of less than 6. Therefore, the adhesive composition for a non-aqueous secondary battery functional layer of the present invention has excellent dispersion stability, and use of this adhesive composition enables the formation of a functional layer that improves the high-temperature storage characteristics of a secondary battery.

[0048] Additionally, the adhesive composition of the present invention generally does not contain inorganic particles.

[0049] As described above, the reason why the dispersion stability of the adhesive composition is improved and the high-temperature storage characteristics of the resulting secondary battery are improved by applying and drying the adhesive composition for a non-aqueous secondary battery functional layer on a predetermined separator substrate and forming a coating film having 86° gloss and 60° gloss within the specified ranges is unclear, but is speculated as follows. Specifically, it is speculated that in an adhesive composition having a coating film having 86° gloss and 60° gloss within the above-specified ranges, a good electric double layer is formed between the particulate polymers A and B and the dispersion medium, making it difficult for the particulate polymers A and B to aggregate and settle. Furthermore, it is speculated that an adhesive composition having a coating film having 86° gloss and 60° gloss within the above-specified ranges suppresses the migration of the particulate polymer B in the functional layer formed using the adhesive composition, thereby improving the filling properties of the particulate polymers A and B in the functional layer, thereby suppressing the increase in resistance of the secondary battery after high-temperature storage. More specifically, it is speculated that: if fine polymer particles are well dispersed in the adhesive composition containing coarse polymer particles, the migration of fine polymer particles into the coating film obtained as described above can be suppressed, and as a result, the increase in the glossiness of the coating film surface caused by the fine polymer particles on the coating film surface can be suppressed. In the adhesive composition of the present invention, the particulate polymers A and B are well dispersed and have high dispersion stability, so the migration of the fine particulate polymer B can be suppressed, and the specified glossiness of the obtained coating film can be maintained low.

[0050] Furthermore, it is known that the surface condition of the object being measured has a greater influence on glossiness than its color (T.IEE Japan, Vol. 113-C, No. 11, '93, Study on the Effect of Object Color on Glossiness, pp. 1013-1022). Therefore, it is speculated that the glossiness of a coating film reflects the surface condition of the coating film (the degree of filling of the particulate polymer).

[0051] In addition, the granular polymer A in the binder composition of the present invention has excellent adhesion as described later, so the binder composition of the present invention can also be preferably used as a binder composition for an adhesive layer or a binder composition for a porous film layer. In addition, in this specification, the functional layer comprising granular polymers A and B and inorganic particles is referred to as a "porous film layer", and the functional layer comprising granular polymers A and B and not comprising inorganic particles is referred to as an "adhesive layer".

[0052] <Granular polymer A>

[0053] When a functional layer is formed on a substrate such as a separator substrate or an electrode substrate using a binder composition for a non-aqueous secondary battery functional layer containing the particulate polymer A, the particulate polymer A plays a role in enabling good adhesion between the particulate polymer A itself and the particulate polymer B used in combination and the substrate. In other words, the particulate polymer A enables the functional layer formed on the substrate to exhibit good adhesion to the substrate.

[0054] In addition, the granular polymer A is a component dispersed in the adhesive composition and slurry composition of the present invention in a state of maintaining a granular shape. In the functional layer formed using the adhesive composition or slurry composition of the present invention, the granular polymer A can be in a granular shape or in any other shape.

[0055] <<Properties>>

[0056] [Volume average particle size D50]

[0057] The volume average particle size D50 of the particulate polymer A is preferably 0.5 μm or greater, more preferably 1.0 μm or greater, and preferably 10 μm or less, more preferably 7.0 μm or less, and even more preferably 5.0 μm or less. If the volume average particle size D50 of the particulate polymer A is at least the lower limit, even when a functional layer containing inorganic particles (described later) is formed, the particulate polymer A protrudes from the functional layer containing the inorganic particles, thereby improving the dry adhesiveness of the functional layer. Furthermore, if the volume average particle size D50 of the particulate polymer A is at or below the upper limit, the particulate polymer A can be effectively prevented from falling out of the functional layer, thereby improving the dry adhesiveness and wet adhesiveness of the functional layer.

[0058] The volume average particle size D50 of the particulate polymer A can be adjusted to a desired range by, for example, the polymerization method and polymerization conditions of the particulate polymer, or sedimentation separation or classification of the obtained polymer.

[0059] [Electrolyte swelling degree]

[0060] The electrolyte swelling degree of granular polymer A is preferably more than 1 times, more preferably more than 1.2 times, in addition, preferably less than 5 times, more preferably less than 4 times, and further preferably less than 3 times. If the electrolyte swelling degree of granular polymer A is above the above lower limit, then in a secondary battery having a functional layer containing granular polymer A, ion conductivity is improved, and it is possible to suppress the internal resistance from rising. As a result, it is possible to enable the obtained secondary battery to exhibit more excellent high-temperature storage characteristics. In addition, if the electrolyte swelling degree of granular polymer A is below the above upper limit, it is possible to suppress the granular polymer A contained in the functional layer from excessively swelling in the electrolyte and hindering the movement of lithium ions, etc., and to suppress the ion conductivity of the functional layer from decreasing. As a result, it is possible to suppress the resistance rise of the secondary battery, and enable the secondary battery to exhibit more excellent high-temperature storage characteristics.

[0061] The degree of swelling of the particulate polymer A with the electrolyte solution can be controlled by changing the composition of the particulate polymer A, for example.

[0062] [Glass transition temperature]

[0063] The glass transition temperature of the granular polymer A is not particularly limited, but is preferably 30°C or higher, more preferably 40°C or higher, and preferably 110°C or lower, more preferably 90°C or lower. If the adhesive composition contains a granular polymer A having a glass transition temperature of 110°C or lower, the battery component (separator, electrode) having a functional layer formed using the adhesive composition can exhibit high dry adhesion, and the substrate and the functional layer can be well adhered to each other, thereby suppressing the powdering of the formed functional layer. In addition, if the glass transition temperature of the granular polymer A is 30°C or higher, the anti-blocking property of the battery component having the functional layer can be improved. Here, the "anti-blocking property" of the functional layer refers to the property of suppressing the unexpected adhesion (blocking) of the functional layer when it is stacked with other components during the manufacturing process of the non-aqueous secondary battery.

[0064] In the present invention, the "glass transition temperature" of the particulate polymer can be measured using a differential scanning calorimeter in accordance with JIS K 7121 (1987).

[0065] The glass transition temperature of the particulate polymer A can be controlled by, for example, changing the composition of the particulate polymer.

[0066] <<Composition>>

[0067] The polymer constituting the particulate polymer A is not particularly limited as long as it can exhibit adhesiveness, and a polymer having any composition can be used.

[0068] As a polymer preferably used as the particulate polymer A, a polymer containing at least one monomer unit selected from, for example, an aromatic vinyl monomer unit, a (meth)acrylate monomer unit, a nitrile group-containing monomer unit, an N-hydroxymethylamide group-containing monomer unit, an epoxy group-containing unsaturated monomer unit, a crosslinking monomer unit, and an acidic group-containing monomer unit is preferred. A polymer containing at least one monomer unit selected from an aromatic vinyl monomer unit, a (meth)acrylate monomer unit, a crosslinking monomer unit, and an epoxy group-containing unsaturated monomer unit is more preferred. A polymer containing all monomer units of an aromatic vinyl monomer unit, a (meth)acrylate monomer unit, a crosslinking monomer unit, and an epoxy group-containing unsaturated monomer unit is further preferred.

[0069] [Aromatic vinyl monomer unit]

[0070] The aromatic vinyl monomer capable of forming the aromatic vinyl monomer unit is not particularly limited, and examples thereof include styrene, α-methylstyrene, styrenesulfonic acid, butoxystyrene, and vinylnaphthalene, with styrene being preferred. These aromatic vinyl monomers may be used alone or in combination of two or more at any ratio.

[0071] When all repeating units contained in granular polymer A are taken as 100 mass %, the ratio of the aromatic vinyl monomer units in granular polymer A is preferably more than 25 mass %, more preferably more than 30 mass %, further preferably more than 60 mass %, in addition, preferably below 95 mass %, more preferably below 90 mass %, further preferably below 85 mass %. If the ratio of the aromatic vinyl monomer units in granular polymer A is above the above lower limit, the elasticity of granular polymer A improves, and the intensity of the functional layer obtained can be ensured, as a result, the adhesion between the functional layer and the substrate can be improved. In addition, if the ratio of the aromatic vinyl monomer units in granular polymer A is below the above upper limit, the flexibility of granular polymer A improves, and the film-forming property when using the binder composition to form the functional layer improves, as a result, the adhesion between the functional layer and the substrate can be improved.

[0072] [(Meth)acrylate monomer unit]

[0073] Examples of the (meth)acrylate monomers capable of forming (meth)acrylate monomer units include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, and stearyl acrylate; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate. These may be used alone or in combination. Among these, n-butyl acrylate is preferred.

[0074] In the present invention, (meth)acrylic acid means acrylic acid and / or methacrylic acid.

[0075] When all repeating units contained in the granular polymer A are taken as 100% by mass, the proportion of the (meth)acrylate monomer units in the granular polymer A is preferably 3% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. Furthermore, it is preferably 40% by mass or less, and more preferably 30% by mass or less. If the proportion of the (meth)acrylate monomer units in the granular polymer A is above the above lower limit, the dry adhesiveness of the resulting functional layer can be improved. Furthermore, if the proportion of the (meth)acrylate monomer units in the granular polymer A is below the above upper limit, the internal resistance of the secondary battery can be suppressed by suppressing the electrolyte swelling of the granular polymer A from becoming excessively high, thereby further improving the high-temperature storage characteristics of the secondary battery.

[0076] [Nitrile-containing monomer unit]

[0077] Examples of nitrile-containing monomers that can form nitrile-containing monomer units include α,β-ethylenically unsaturated nitrile monomers. Specifically, the α,β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α,β-ethylenically unsaturated compound having a nitrile group. Examples include acrylonitrile; α-halogenated acrylonitriles such as α-chloroacrylonitrile and α-bromoacrylonitrile; and α-alkylacrylonitriles such as methacrylonitrile and α-ethylacrylonitrile. Among these, acrylonitrile is preferred.

[0078] These nitrile group-containing monomers may be used alone or in combination of two or more at any ratio.

[0079] When all repeating units contained in the granular polymer A are taken as 100% by mass, the proportion of nitrile group-containing monomer units in the granular polymer A is preferably 3% by mass or greater, more preferably 4% by mass or greater, and even more preferably 6% by mass or greater, and is preferably 30% by mass or less, and more preferably 25% by mass or less. If the proportion of nitrile group-containing monomer units in the granular polymer A is greater than the above lower limit, adhesiveness can be improved. Furthermore, if the proportion of nitrile group-containing monomer units in the granular polymer A is less than the above upper limit, interference with the movement of lithium ions and the like due to excessive swelling can be suppressed, thereby preventing a decrease in the ionic conductivity of the functional layer.

[0080] [Containing N-methylolamide monomer units]

[0081] Examples of N-methylolamide-containing monomers that can form N-methylolamide-containing monomer units include N-methylol(meth)acrylamide and N-butoxymethylol(meth)acrylamide. Of these, N-methylolacrylamide is preferred. These N-methylolamide-containing monomers can be used alone or in combination.

[0082] [Epoxy-containing unsaturated monomer units]

[0083] Examples of epoxy-containing unsaturated monomers capable of forming epoxy-containing unsaturated monomer units include unsaturated glycidyl ethers such as vinyl glycidyl ether, allyl glycidyl ether, butenyl glycidyl ether, o-allylphenyl glycidyl ether, and glycidyl (2-butenyl) ether; and monocyclic rings of dienes or polyenes such as butadiene monoepoxide, chloroprene monoepoxide, 4,5-epoxy-2-pentene, 3,4-epoxy-1-vinylcyclohexene, and 1,2-epoxy-5,9-cyclododecadiene. Oxides; alkenyl epoxides such as 3,4-epoxy-1-butene, 1,2-epoxy-5-hexene, and 1,2-epoxy-9-decene; glycidyl esters of unsaturated carboxylic acids such as glycidyl acrylate, glycidyl methacrylate, glycidyl crotonate, glycidyl 4-heptenoate, glycidyl sorbate, glycidyl linoleate, glycidyl 4-methyl-3-pentenoate, glycidyl ester of 3-cyclohexenecarboxylic acid, and glycidyl ester of 4-methyl-3-cyclohexenecarboxylic acid. From the viewpoint of further improving the high-temperature storage characteristics of the resulting secondary battery, unsaturated glycidyl ethers and glycidyl esters of unsaturated carboxylic acids are preferably used, and allyl glycidyl ether, glycidyl (2-butenyl) ether, and glycidyl methacrylate are more preferably used, and glycidyl methacrylate is even more preferably used.

[0084] These epoxy group-containing unsaturated monomers may be used alone or in combination of two or more at any ratio.

[0085] When all repeating units contained in the particulate polymer A are taken as 100% by mass, the proportion of the epoxy-containing unsaturated monomer units in the particulate polymer A is preferably 1.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 10% by mass or more, and is preferably 20% by mass or less, and more preferably 15% by mass or less. When the proportion of the epoxy-containing unsaturated monomer units in the particulate polymer A is at least the above lower limit, the dry adhesiveness of the resulting functional layer can be improved.

[0086] [Crosslinking monomer unit]

[0087] As a cross-linking monomer capable of forming a cross-linking monomer unit, for example, a multifunctional monomer having two or more polymerizable reactive groups in the monomer can be cited. As a multifunctional monomer, for example: divinyl compounds such as allyl methacrylate and divinylbenzene; di(meth)acrylate compounds such as diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butanediol diacrylate; tri(meth)acrylate compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; and epoxy-containing unsaturated monomers listed in the above-mentioned [epoxy-containing unsaturated monomer unit] item. Among them, ethylene glycol dimethacrylate is preferred. In addition, these cross-linking monomers can be used alone or in combination of two or more in any ratio.

[0088] When all repeating units contained in the particulate polymer A are taken as 100% by mass, the proportion of the crosslinkable monomer units in the particulate polymer A is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and even more preferably 0.5% by mass or more, and is preferably 1.0% by mass or less, and more preferably 0.8% by mass or less. When the proportion of the crosslinkable monomer units in the particulate polymer A is within the above range, the adhesiveness of the resulting functional layer can be improved.

[0089] [Acidic group-containing monomer unit]

[0090] Examples of the acidic group-containing monomer capable of forming the acidic group-containing monomer unit include carboxylic acid group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, etc. These may be used alone or in combination of two or more.

[0091] Examples of the carboxylic acid group-containing monomer include ethylenically unsaturated monocarboxylic acids and derivatives thereof, ethylenically unsaturated dicarboxylic acids and anhydrides thereof, and derivatives thereof.

[0092] Examples of ethylenically unsaturated monocarboxylic acids include acrylic acid, methacrylic acid, crotonic acid, etc. Examples of derivatives of ethylenically unsaturated monocarboxylic acids include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, and β-diaminoacrylic acid.

[0093] Examples of ethylenically unsaturated dicarboxylic acids include maleic acid, fumaric acid, itaconic acid, and mesaconic acid. Examples of anhydrides of ethylenically unsaturated dicarboxylic acids include maleic anhydride, acrylic anhydride, methylmaleic anhydride, and dimethylmaleic anhydride. Examples of derivatives of ethylenically unsaturated dicarboxylic acids include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, diphenyl maleate, nonyl maleate, decyl maleate, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleate.

[0094] Examples of the sulfonic acid group-containing monomer include vinyl sulfonic acid, methylvinyl sulfonic acid, (meth)allyl sulfonic acid, 2-sulfonic ethyl (meth)acrylate, 2-acrylamide-2-methylpropanesulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid.

[0095] In the present invention, "(meth)allyl group" means an allyl group and / or a methallyl group.

[0096] Examples of the phosphoric acid group-containing monomer include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate.

[0097] Among these, as the acidic group-containing monomer, a carboxylic acid group-containing monomer is preferred, and methacrylic acid is more preferred.

[0098] When all repeating units contained in the granular polymer A are taken as 100% by mass, the proportion of the acidic group-containing monomeric units in the granular polymer A is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.15% by mass or more. Furthermore, it is preferably 2% by mass or less, and more preferably 1% by mass or less. If the proportion of the acidic group-containing monomeric units in the granular polymer A is within the above range, the particles can be stabilized, further improving the dispersion stability of the adhesive composition.

[0099] <<Preparation of Granular Polymer A>>

[0100] The particulate polymer A can be prepared by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water.

[0101] Furthermore, the polymerization method is not particularly limited, and any method such as suspension polymerization, emulsion polymerization coagulation, and pulverization can be used. Among them, suspension polymerization and emulsion polymerization coagulation are preferred, and suspension polymerization is more preferred. In addition, as the polymerization reaction, any reaction such as free radical polymerization and living radical polymerization can be used.

[0102] [Other compounding ingredients]

[0103] Furthermore, the monomer composition used in preparing the granular polymer A may contain other ingredients such as a chain transfer agent, a polymerization regulator, a polymerization reaction retarder, a reactive fluidizing agent, a filler, a flame retardant, an antioxidant, and a colorant in any amount.

[0104] Here, as an example, a method for producing the particulate polymer A by the suspension polymerization method will be described.

[0105] [Preparation of granular polymer by suspension polymerization]

[0106] (1) Preparation of monomer composition

[0107] First, a monomer composition (A) is prepared having a composition corresponding to the composition of the granular polymer A. At this time, various monomers are blended according to the composition of the granular polymer A, and other compounding agents are further mixed as needed.

[0108] (2) Droplet formation

[0109] Next, the monomer composition (A) is dispersed in water, and a polymerization initiator is added to form droplets of the monomer composition (A). The method for forming the droplets is not particularly limited, and the droplets can be formed by shearing and stirring the water containing the monomer composition (A) using a disperser such as an emulsifier.

[0110] In this case, examples of the polymerization initiator used include oil-soluble polymerization initiators such as t-butyl peroxy-2-ethylhexanoate and azobisisobutyronitrile. Furthermore, the polymerization initiator may be added after the monomer composition (A) is dispersed in water and before droplets are formed, or may be added to the monomer composition (A) before it is dispersed in water.

[0111] Furthermore, from the perspective of stabilizing the droplets of the monomer composition (A) formed in water, it is preferred to add a dispersion stabilizer to water to form the droplets of the monomer composition (A). In this case, the dispersion stabilizer may be, for example, an inorganic dispersion stabilizer such as an inorganic metal salt (e.g., magnesium hydroxide, calcium hydroxide, barium hydroxide) or an organic dispersion stabilizer such as sodium dodecylbenzenesulfonate. Among these, an inorganic dispersion stabilizer is preferred, and magnesium hydroxide is more preferred.

[0112] Here, from the viewpoint of improving the dispersion stability of the droplets of the monomer composition (A) in water, the dispersion stabilizer is preferably used in a state dispersed in an aqueous dispersion medium. The aqueous dispersion medium is not limited, and examples thereof include water, hydrophilic solvents such as alcohol compounds, and mixtures of water and hydrophilic solvents.

[0113] In the preparation of the dispersion of the dispersion stabilizer, for example, a method of directly mixing the dispersion stabilizer and an aqueous medium can be adopted. Preferably, two or more compounds (precursor compounds) serving as precursors of the dispersion stabilizer are mixed and reacted in an aqueous medium to obtain the dispersion stabilizer.

[0114] The above-mentioned precursor compound is not particularly limited. When an inorganic dispersion stabilizer such as a poorly water-soluble hydroxide such as magnesium hydroxide, calcium hydroxide, or barium hydroxide is used as a dispersion stabilizer, a combination of a water-soluble polyvalent metal salt and an alkali metal hydroxide can be cited as two or more precursor compounds.

[0115] As water-soluble polyvalent metal salts, hydrochlorides, sulfates, nitrates, acetates, etc. of polyvalent metals such as magnesium, calcium, aluminum, iron, copper, manganese, nickel, and tin can be enumerated. Among these, water-soluble salts of magnesium or calcium are preferred. In addition, as alkali metal hydroxides, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. can be enumerated. When, for example, magnesium hydroxide is used as a dispersion stabilizer, a combination of two or more precursor compounds is preferably used, such as magnesium chloride and sodium hydroxide.

[0116] The method for mixing two or more precursor compounds in an aqueous medium is not particularly limited. When a combination of a water-soluble polyvalent metal salt and an alkali metal hydroxide is prepared, a method is preferably performed by dropwise adding an aqueous medium solution of the alkali metal hydroxide to an aqueous medium solution of the water-soluble polyvalent metal salt under stirring.

[0117] The amount of the water-soluble polyvalent metal salt used is preferably 1 part by mass or more, and is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, relative to 100 parts by mass of the monomer composition.

[0118] (3) Aggregation

[0119] After droplets of the monomer composition (A) are formed, the water containing the formed droplets is heated to initiate polymerization. The polymerization reaction temperature is preferably 50° C. to 95° C. The polymerization reaction time is preferably 1 hour to 10 hours, preferably 8 hours or less, and more preferably 6 hours or less.

[0120] (4) Cleaning, filtering, dehydration and drying processes

[0121] After completion of polymerization, the particulate polymer A can be obtained by washing, filtering, and drying the water containing the particulate polymer A according to conventional methods. Preferably, the aqueous dispersion containing the particulate polymer A is subjected to acid washing. Specifically, it is preferred to add an acid to the aqueous dispersion containing the particulate polymer A while stirring to adjust the pH of the aqueous dispersion to a desired value, followed by further stirring to wash the particulate polymer A. The acid used for acid washing is not particularly limited; any acid such as hydrochloric acid, sulfuric acid, and nitric acid can be used, but sulfuric acid is preferably used.

[0122] During the acid washing, the pH of the aqueous dispersion containing the particulate polymer A (the pH at the end point of the acid washing) is preferably 7.0 or less, more preferably 6.5 or less, and even more preferably 5.5 or less.

[0123] The lower the pH at the end of acid washing, the more effectively the metal ions contained in the dispersion stabilizer can be removed, and the more side reactions during high-temperature storage of the secondary battery can be suppressed. As a result, the high-temperature storage characteristics of the secondary battery can be further improved.

[0124] The acid washing time of the particulate polymer A (the time for further stirring after adjusting the pH of the aqueous dispersion to a desired value) is preferably 0.5 hours or longer, more preferably 1.0 hours or longer, and even more preferably 5 hours or longer.

[0125] The longer the acid washing time is, the more metal ions contained in the dispersion stabilizer can be removed, and the more side reactions during high-temperature storage of the secondary battery can be suppressed. As a result, the high-temperature storage characteristics of the secondary battery can be further improved.

[0126] It is preferred that the acid-washing be followed by a water-washing treatment (water-washing, filtration, and dehydration). Specifically, the aqueous dispersion containing the particulate polymer A after the acid-washing as described above is filtered, and then ion-exchanged water is added to the obtained solid content to obtain an aqueous dispersion of the particulate polymer A, which is then stirred for a predetermined period of time, filtered, and dehydrated.

[0127] In this case, it is preferred to repeat the water washing treatment (water washing, filtration, and dehydration) until the conductivity of the aqueous dispersion of the particulate polymer A becomes 1 mS / cm or less, preferably 0.1 mS / cm or less.

[0128] The electrical conductivity can be measured by, for example, "COND METER ES-71" manufactured by HORIBA CORPORATION.

[0129] <Granular polymer B>

[0130] The particulate polymer B is a component that binds the particulate polymer A and other components in the functional layer formed using the binder composition containing the particulate polymer A and the particulate polymer B and can prevent the particulate polymer A and other components from falling out of the functional layer.

[0131] In addition, the granular polymer B is a component dispersed in the adhesive composition or slurry composition of the present invention in a state of maintaining a granular shape. In the functional layer formed using the adhesive composition or slurry composition of the present invention, the granular polymer B can be in a granular shape or in any other shape.

[0132] <<Properties>>

[0133] [Volume average particle size D50]

[0134] The volume average particle diameter D50 of the particulate polymer B is preferably smaller than the volume average particle diameter D50 of the particulate polymer A. Furthermore, the volume average particle diameter D50 of the particulate polymer B is preferably 0.1 μm or greater, more preferably 0.2 μm or greater, and preferably 1.0 μm or less, more preferably 0.5 μm or less. If the volume average particle diameter D50 of the particulate polymer B is within the above range, migration of the particulate polymer B during application of the adhesive composition can be effectively suppressed, allowing the particulate polymers A and B to be effectively filled into the functional layer. As a result, the high-temperature storage characteristics of the secondary battery can be further improved.

[0135] The volume average particle size D50 of the particulate polymer B can be measured by the method described in Examples. The volume average particle size D50 of the particulate polymer B can be controlled in the same manner as the volume average particle size D50 of the particulate polymer A.

[0136] [Glass transition temperature]

[0137] The glass transition temperature of the particulate polymer B is not particularly limited, but is preferably -100°C or higher, more preferably -90°C or higher, and even more preferably -80°C or higher, and is preferably 30°C or lower, more preferably 20°C or lower, and even more preferably 15°C or lower.

[0138] When the glass transition temperature of the particulate polymer B is within the above range, the dry adhesiveness of the functional layer can be improved, and the high-temperature storage characteristics of the secondary battery can be further improved.

[0139] The glass transition temperature of the particulate polymer B can be measured in the same manner as the glass transition temperature of the particulate polymer A. The glass transition temperature of the particulate polymer B can be controlled by, for example, changing the composition of the particulate polymer B.

[0140] <<Composition>>

[0141] The polymer constituting the particulate polymer B is not particularly limited as long as it is a polymer different from the particulate polymer A. For example, a polymer containing monomer units that can be contained in the particulate polymer A can be used.

[0142] Specifically, as a polymer that can be preferably used as the particulate polymer B, a polymer containing at least one monomer unit selected from, for example, an aromatic vinyl monomer unit, a (meth)acrylate monomer unit, a nitrile group-containing monomer unit, an N-hydroxymethylamide group-containing monomer unit, an epoxy group-containing unsaturated monomer unit, a crosslinking monomer unit, and an acidic group-containing monomer unit is preferred. A polymer containing at least a (meth)acrylate monomer unit is more preferred, and a polymer containing all monomer units of a (meth)acrylate monomer unit, a nitrile group-containing monomer unit, a crosslinking monomer unit, an acidic group-containing monomer unit, and an epoxy group-containing unsaturated monomer unit is further preferred.

[0143] [Aromatic vinyl monomer unit]

[0144] As the aromatic monovinyl monomer capable of forming the aromatic monovinyl monomer, the same monomers as those exemplified as the monomers capable of forming the aromatic monovinyl monomer units that can be contained in the particulate polymer A can be used. Among them, styrene is preferably used.

[0145] When all repeating units contained in the particulate polymer B are taken as 100% by mass, the proportion of the aromatic vinyl monomer units in the particulate polymer B is preferably 10% by mass or more, more preferably 20% by mass or more, and is preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less. When the proportion of the aromatic vinyl monomer units in the particulate polymer B is within this range, both the dry adhesiveness of the functional layer and the high-temperature storage characteristics of the secondary battery can be achieved.

[0146] [(Meth)acrylate monomer unit]

[0147] As the (meth)acrylate monomer capable of forming the (meth)acrylate monomer unit, the same monomers as those listed as the monomers capable of forming the (meth)acrylate monomer unit contained in the particulate polymer A can be used. Among them, n-butyl acrylate is preferably used.

[0148] When all repeating units contained in the granular polymer B are taken as 100% by mass, the proportion of the (meth)acrylate monomer units in the granular polymer B is preferably 80% by mass or more, more preferably 90% by mass or more, and is preferably 97% by mass or less, more preferably 96% by mass or less. When the proportion of the (meth)acrylate monomer units in the granular polymer B is within the above range, the adhesiveness of the granular polymer B can be improved.

[0149] [Nitrile-containing monomer unit]

[0150] As the nitrile group-containing monomer capable of forming the nitrile group-containing monomer unit, there can be used the same monomers as those exemplified as the monomer capable of forming the nitrile group-containing monomer unit that can be contained in the particulate polymer A. Among them, acrylonitrile is preferred.

[0151] When all repeating units contained in the particulate polymer B are taken as 100% by mass, the proportion of the nitrile group-containing monomer units in the particulate polymer B is preferably 1% by mass or more, more preferably 2% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less. If the proportion of the nitrile group-containing monomer units in the particulate polymer B is within the above range, the high-temperature storage characteristics of the secondary battery can be further improved.

[0152] [Containing N-methylolamide monomer units]

[0153] As the N-methylolamide group-containing monomer capable of forming the N-methylolamide group-containing monomer unit, the same monomers as those exemplified as the monomer capable of forming the N-methylolamide group-containing monomer unit that can be contained in the particulate polymer A can be used. Among them, N-methylolacrylamide is preferred.

[0154] When all repeating units contained in the particulate polymer B are taken as 100% by mass, the proportion of the N-methylolamide group-containing monomer units in the particulate polymer B is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, and is preferably 3.0% by mass or less, and more preferably 2.5% by mass or less. If the proportion of the N-methylolamide group-containing monomer units in the particulate polymer B is within the above range, the dispersion stability of the adhesive composition can be further improved, and the adhesive properties of the particulate polymer B can be enhanced.

[0155] [Epoxy-containing unsaturated monomer units]

[0156] As the epoxy-containing unsaturated monomer capable of forming the epoxy-containing unsaturated monomer unit, the same monomers as those exemplified as the monomer capable of forming the epoxy-containing unsaturated monomer unit that can be contained in the particulate polymer A can be used. Among them, glycidyl methacrylate is preferably used.

[0157] When all repeating units contained in the granular polymer B are taken as 100% by mass, the proportion of the epoxy-containing unsaturated monomer units in the granular polymer B is preferably 0.5% by mass or more, more preferably 1% by mass or more, and is preferably 5% by mass or less, more preferably 3% by mass or less. When the proportion of the epoxy-containing unsaturated monomer units in the granular polymer B is within the above range, the adhesiveness of the granular polymer B can be improved.

[0158] [Crosslinking monomer unit]

[0159] As the crosslinkable monomer capable of forming the crosslinkable monomer unit, the same monomers as those exemplified as the monomer capable of forming the crosslinkable monomer unit that can be contained in the particulate polymer A can be used. Among them, allyl methacrylate is preferably used.

[0160] When all repeating units contained in the particulate polymer B are taken as 100% by mass, the proportion of the crosslinkable monomer units in the particulate polymer B is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and is preferably 2.0% by mass or less, more preferably 1.5% by mass or less. If the proportion of the crosslinkable monomer units in the particulate polymer B is within the above range, the dispersion stability of the adhesive composition can be further improved while also enhancing the adhesive properties of the particulate polymer B.

[0161] [Acidic group-containing monomer unit]

[0162] As the acidic group-containing monomer capable of forming the acidic group-containing monomer unit, the same monomers as those exemplified as the monomer capable of forming the acidic group-containing monomer unit that can be contained in the particulate polymer A can be used. Among them, from the viewpoint of further improving the dispersion stability of the binder composition and the high-temperature storage characteristics of the secondary battery, a carboxylic acid group-containing monomer is preferred, and methacrylic acid is more preferred.

[0163] When all repeating units contained in the particulate polymer B are taken as 100% by mass, the proportion of the acidic group-containing monomeric units in the particulate polymer B is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, and is preferably 5.0% by mass or less, more preferably 4.0% by mass or less. If the proportion of the acidic group-containing monomeric units in the particulate polymer B is within the above range, the dispersion stability of the binder composition and the high-temperature storage characteristics of the secondary battery can be further improved.

[0164] <<Preparation Method of Granular Polymer B>>

[0165] The granular polymer B is not particularly limited and can be prepared in the same manner as the granular polymer A described above.

[0166] <Dispersion medium>

[0167] As the dispersion medium contained in the adhesive composition of the present invention, water is generally used. In addition, a mixture of water and an organic solvent can also be used as a dispersion medium. Here, as an organic solvent, there is no particular limitation, and examples thereof include: cyclic aliphatic hydrocarbon compounds such as cyclopentane and cyclohexane; aromatic hydrocarbon compounds such as toluene and xylene; ketone compounds such as methyl ethyl ketone and cyclohexanone; ester compounds such as ethyl acetate, butyl acetate, γ-butyrolactone, and ε-caprolactone; nitrile compounds such as acetonitrile and propionitrile; ether compounds such as tetrahydrofuran and ethylene glycol diethyl ether; alcohol compounds such as methanol, ethanol, isopropanol, ethylene glycol, and ethylene glycol monomethyl ether; amide compounds such as N-methylpyrrolidone (NMP) and N,N-dimethylformamide, etc. These can be used alone or in combination of two or more in any ratio.

[0168] The proportion of water in the mixture of water and the organic solvent is usually 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0169] The amount of the dispersion medium in the adhesive composition is preferably set so that the solid content concentration of the adhesive composition falls within a desired range. Specifically, the solid content concentration of the adhesive composition is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, and particularly preferably 65% by mass or less.

[0170] <Other ingredients>

[0171] There are no particular limitations on the other components that may be optionally included in the adhesive composition, as long as they do not adversely affect the battery reaction in the secondary battery having the functional layer.

[0172] Examples of other ingredients include preservatives, emulsifiers, dispersants, wetting agents, leveling agents, electrolyte decomposition inhibitors, and water-soluble polymers. In the present invention, "water-soluble" means that when 0.5% of the substance is dissolved in 100g of water at 25°C, the insoluble content is less than 1.0% by mass. Furthermore, for substances whose solubility varies depending on the pH of water, the polymer is considered "water-soluble" if it meets the above criteria at at least one pH. Examples of water-soluble polymers include natural polymers, semi-synthetic polymers, and synthetic polymers.

[0173] <Glossiness>

[0174] As described above, the coating film obtained by applying and drying the adhesive composition of the present invention on a polyethylene separator substrate needs to have an 86° glossiness of 1 or more and 70 or less, and a 60° glossiness of less than 6.

[0175] When the 86° glossiness and 60° glossiness of the coating film are outside the above ranges, the dispersion stability of the binder composition and the high-temperature storage characteristics of a secondary battery having the obtained functional layer may deteriorate.

[0176] From the perspective of further improving the dispersion stability of the binder composition and the high-temperature storage characteristics of the secondary battery, the 86° gloss of the coating is preferably 50 or less, more preferably 30 or less. Furthermore, from the same perspective, the 60° gloss of the coating is preferably 5 or less, more preferably 4.5 or less. The lower limit of the 60° gloss of the coating is not particularly limited, but the 60° gloss is preferably 1 or greater, more preferably 1.5 or greater.

[0177] The 86° gloss and 60° gloss of the above-mentioned coating film can be controlled by adjusting, for example, the following conditions: the composition of the granular polymer A and / or the granular polymer B; the mass ratio of the granular polymer A to the granular polymer B in the binder composition; the amount of the water-soluble multivalent metal salt used in the preparation of the dispersion stabilizer used when preparing the granular polymer A by suspension polymerization; the pickling time of the granular polymers A and B; the endpoint pH of the aqueous dispersion when the granular polymers A and B are pickled; the pH of the binder composition; the volume average particle size D50 of the granular polymers A and B, etc.

[0178] Furthermore, from the perspective of further improving the dispersion stability of the adhesive composition while further improving the high-temperature storage characteristics of the secondary battery, the ratio of the 86° glossiness of the above-mentioned coating film to the 60° glossiness (86° glossiness / 60° glossiness) is preferably greater than 1, and is preferably less than 50, more preferably less than 20, and even more preferably less than 10.

[0179] <Ratio of Particulate Polymer A to B in the Binder Composition>

[0180] The mass ratio of the particulate polymer A to the particulate polymer B in the binder composition (particulate polymer A:particulate polymer B) is preferably 50:50 or greater and 95:5 or less, more preferably 60:40 or greater and 95:5 or less, and even more preferably 70:30 or greater and 95:5 or less. If the mass ratio of the particulate polymer A to the particulate polymer B in the binder composition is within this range, powdering of the functional layer can be suppressed, thereby improving the dry and wet adhesive properties of the functional layer and further enhancing the high-temperature storage characteristics of the secondary battery. Furthermore, if the mass ratio of the particulate polymer A to the particulate polymer B is within this range, the gloss of the coating film can be controlled within a suitable range.

[0181] <Contents of Particulate Polymers A and B in the Adhesive Composition>

[0182] The total content of the particulate polymers A and B in the adhesive composition is not particularly limited, but is preferably 75% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more relative to the total solid content of the adhesive composition.

[0183] <pH of the adhesive composition>

[0184] When the dispersion medium of the binder composition is water, the pH of the binder composition is preferably greater than 7.5, and is preferably less than 10.0, more preferably less than 9.0, and further preferably less than 8.5. If the pH of the binder composition is within the above range, the migration of the particulate polymer B can be suppressed when the binder composition or the slurry composition is applied to the substrate, thereby further improving the high-temperature storage characteristics of the secondary battery. In addition, by making the pH of the binder composition greater than the above lower limit, the stability of the binder composition or the slurry composition when applied to the substrate can be improved. In addition, by making the pH of the binder composition less than the above upper limit, the dry adhesion and wet adhesion of the functional layer can be improved.

[0185] The pH of the adhesive composition can be appropriately controlled by adding an acid such as hydrochloric acid or an alkali such as sodium hydroxide to the adhesive composition.

[0186] <Method for preparing adhesive composition>

[0187] The binder composition for a non-aqueous secondary battery functional layer of the present invention can be prepared by stirring and mixing the particulate polymer A, the particulate polymer B, and any of the other components described above in the presence of a dispersion medium such as water. Furthermore, when a dispersion of the particulate polymers A and B is used to prepare the binder composition, the liquid component contained in these dispersions can be directly utilized as the dispersion medium for the binder composition. Alternatively, the binder composition can be prepared using, for example, the water in the acid-washed aqueous dispersion of the particulate polymer A and / or the acid-washed aqueous dispersion of the particulate polymer B as the dispersion medium.

[0188] The stirring method is not particularly limited and can be performed using known methods. Specifically, the adhesive composition can be prepared by mixing the above-mentioned components with a dispersion medium using a conventional stirring vessel, ball mill, sand mill, bead mill, pigment disperser, ultrasonic disperser, attritor, homogenizer, planetary mixer, Filmix, or the like. The mixing of the above-mentioned components with the dispersion medium can generally be performed at room temperature to 80°C for 10 minutes to several hours.

[0189] (Slurry composition for non-aqueous secondary battery functional layer)

[0190] The slurry composition of the present invention is a slurry containing the binder composition of the present invention and inorganic particles, and further containing any other components, and using water or the like as a dispersion medium.

[0191] The slurry composition of the present invention is prepared using the binder composition of the present invention and therefore has excellent dispersion stability. Specifically, in the slurry composition of the present invention, the formation of aggregates can be suppressed by agglomerating the particulate polymers A and B with the inorganic particles. Therefore, by using the slurry composition of the present invention, a functional layer that can improve the high-temperature storage characteristics of the secondary battery can be formed.

[0192] Furthermore, the slurry composition of the present invention contains the above-mentioned particulate polymers A and B, so the obtained functional layer has excellent adhesiveness. Furthermore, since the slurry composition of the present invention contains inorganic particles, the obtained functional layer has excellent heat resistance and strength.

[0193] <Adhesive composition>

[0194] The binder composition described above is used as the binder composition of the present invention. The amount of the binder composition in the slurry composition is not particularly limited. The binder composition can be added in an amount such that the amount of particulate polymers A and B derived from the binder composition is 10 parts by mass or more and 200 parts by mass or less, calculated as solids, per 100 parts by mass of the inorganic particles.

[0195] <Inorganic particles>

[0196] The inorganic particles contained in the slurry composition of the present invention are materials that can impart strength and heat resistance to the resulting functional layer. Specifically, by including inorganic particles in the slurry composition, the resulting functional layer can have both the adhesiveness imparted by the particulate polymers A and B and the strength and heat resistance imparted by the inorganic particles.

[0197] As the material of inorganic particles, it is preferred that the material be stably present and electrochemically stable under the use environment of the secondary battery. From this viewpoint, as the preferred material of inorganic particles, there can be mentioned: oxide particles such as aluminum oxide (Alumina), aluminum oxide hydrate (boehmite (AlOOH)), gibbsite (Al (OH) 3), silicon oxide, magnesium oxide (Magnesia), magnesium hydroxide, calcium oxide, titanium oxide (Titania), barium titanate (BaTiO 3), ZrO, aluminum oxide-silicon dioxide composite oxide; Nitride particles such as aluminum nitride and boron nitride; Covalent bond crystal particles such as silicon and diamond; Insoluble ionic crystal particles such as barium sulfate, calcium fluoride, and barium fluoride; Clay particles such as talc, montmorillonite, kaolin, and calcined kaolin. Among them, it is preferred that the inorganic particles include aluminum oxide, and it is more preferred that the inorganic particles are aluminum oxide. In addition, these inorganic particles can be subjected to element replacement, surface treatment, solid solutionization, etc. as needed.

[0198] These inorganic particles may be used alone or in combination of two or more at any ratio.

[0199] The volume average particle size D50 of the inorganic particles is preferably 0.1 μm or more, more preferably 0.2 μm or more, further preferably 0.7 μm or more, and preferably 1 μm or less, more preferably 0.9 μm or less. If the volume average particle size D50 of the inorganic particles is above the above lower limit, it is possible to suppress the decrease in the ionic conductivity of the functional layer caused by the inorganic particles being densely filled in the functional layer, thereby improving the battery characteristics (especially output characteristics) of the secondary battery. In addition, if the volume average particle size D50 of the inorganic particles is below the above upper limit, even when the functional layer is thinned, the battery components (separators, electrodes) having the functional layer can fully exert their heat shrinkage resistance.

[0200] <Other ingredients>

[0201] As other components that can be combined in the slurry composition, there are no particular limitations, and the same components as those that can be combined in the adhesive composition of the present invention can be cited. In addition, the other components can be used alone or in combination of two or more in any ratio.

[0202] <Preparation of slurry composition>

[0203] The preparation method of the slurry composition is not particularly limited. The slurry composition of the present invention can be prepared by mixing the binder composition, inorganic particles, and other components used as needed in the presence of a dispersion medium such as water. The above-mentioned dispersion medium can be used directly as the dispersion medium such as water contained in the binder composition, or it can be a newly added dispersion medium. In addition, the mixing method used when preparing the slurry composition is not particularly limited, and mixing can be performed using a commonly used stirrer or disperser.

[0204] (Separator for non-aqueous secondary batteries)

[0205] The separator for a non-aqueous secondary battery of the present invention (hereinafter, sometimes simply referred to as “separator”) includes a separator base and a functional layer provided on at least one surface of the separator base.

[0206] <Spacer base material>

[0207] The spacer substrate is not particularly limited, and examples thereof include known spacer substrates such as organic spacer substrates. An organic spacer substrate is a porous member composed of an organic material. Examples of organic spacer substrates include microporous films or nonwoven fabrics made of polyolefin resins such as polyethylene and polypropylene, and aromatic polyamide resins. Microporous films and nonwoven fabrics made of polyethylene are preferred due to their excellent strength.

[0208] Functional layer

[0209] The functional layer is formed using the adhesive composition of the present invention, preferably the slurry composition of the present invention. Specifically, the functional layer can be formed by, for example, applying the adhesive composition or slurry composition of the present invention to the surface of the spacer substrate to form a coating film, and then drying the formed coating film. In other words, the functional layer is formed from the dried product of the adhesive composition or slurry composition of the present invention.

[0210] When the adhesive composition of the present invention is used to form a functional layer, the functional layer generally contains the above-mentioned particulate polymers A and B and optionally contains the above-mentioned other components. Therefore, the functional layer can appropriately function as an adhesive layer.

[0211] When the slurry composition of the present invention is used to form a functional layer, the functional layer generally comprises the granular polymers A and B and the inorganic particles, and optionally comprises the other components. Therefore, the functional layer has excellent adhesiveness and can function as a porous membrane layer with excellent heat resistance and strength.

[0212] In addition, the abundance ratio of each component contained in the functional layer (excluding dispersion media such as water) is generally the same as the abundance ratio of each component contained in the above-mentioned adhesive composition or slurry composition, and the preferred abundance ratio of each component in the functional layer is also the same as the preferred abundance ratio of each component in the above-mentioned adhesive composition or slurry composition.

[0213] Furthermore, the separator of the present invention can enable the secondary battery to exhibit excellent high-temperature storage characteristics because the functional layer is formed of the adhesive composition or slurry composition of the present invention.

[0214] <Method for manufacturing spacer>

[0215] The method for producing the separator of the present invention is not particularly limited, and the separator of the present invention can be produced by, for example, forming a functional layer on the above-mentioned separator substrate.

[0216] Here, as a method for producing the separator of the present invention by forming a functional layer on a separator substrate, for example, the following method can be mentioned.

[0217] 1) A method of supplying the adhesive composition or slurry composition of the present invention to the surface of a spacer substrate and then drying it; and

[0218] 2) A method in which the adhesive composition or slurry composition of the present invention is supplied onto a release substrate and dried to produce a functional layer, and the obtained functional layer is transferred to the surface of a separator substrate.

[0219] Among these, method 1) is particularly preferred because it allows for easy control of the thickness of the functional layer. Specifically, method 1) includes: supplying the adhesive composition or slurry composition onto the spacer substrate (supplying step); and drying the adhesive composition or slurry composition applied to the spacer substrate to form the functional layer (drying step).

[0220] <<Supply process>>

[0221] Furthermore, in the supplying step, methods for supplying the adhesive composition or slurry composition onto the spacer substrate include: coating the adhesive composition or slurry composition on the surface of the spacer substrate; and immersing the spacer substrate in the adhesive composition or slurry composition. Specific examples of these methods, without particular limitation, include a doctor blade method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method, a dip coating method, a spray coating method, and a vacuum impregnation method.

[0222] <<Drying process>>

[0223] In the drying step, the method for drying the adhesive composition or slurry composition on the spacer substrate is not particularly limited, and known methods can be used. Examples of drying methods include drying with warm air, hot air, or low-humidity air; vacuum drying; and drying with irradiation such as infrared rays or electron beams.

[0224] Furthermore, from the viewpoint of improving the battery characteristics of the secondary battery while ensuring the strength of the functional layer, the thickness of the functional layer formed on the separator substrate as described above is preferably 0.1 μm to 10 μm.

[0225] (Electrodes for non-aqueous secondary batteries)

[0226] The nonaqueous secondary battery electrode of the present invention (hereinafter, sometimes simply referred to as “electrode”) includes an electrode substrate and a functional layer provided on at least one surface of the electrode substrate.

[0227] <Electrode base material>

[0228] The electrode substrate (positive electrode substrate and negative electrode substrate) is not particularly limited, and examples thereof include an electrode substrate in which an electrode composite material layer is formed on a current collector.

[0229] Here, the current collector, the electrode active material (positive electrode active material, negative electrode active material) in the electrode composite material layer and the binding material for the electrode composite material layer (binding material for the positive electrode composite material layer, binding material for the negative electrode composite material layer), and the method for forming the electrode composite material layer on the current collector can use known ones, for example, those described in Japanese Patent Gazette No. 2013-145763 and International Publication No. 2015 / 129408 can be used.

[0230] Functional layer

[0231] The functional layer is formed using the binder composition of the present invention, preferably the slurry composition of the present invention. Specifically, the functional layer can be formed by, for example, applying the binder composition or slurry composition of the present invention to the surface of the electrode substrate to form a coating film, and then drying the formed coating film. In other words, the functional layer is formed from the dried product of the binder composition or slurry composition of the present invention.

[0232] The details of the functional layer are the same as those described in the above-mentioned section "Separator for non-aqueous secondary battery", and therefore, description thereof will be omitted.

[0233] Furthermore, since the functional layer of the electrode of the present invention is formed from the binder composition or slurry composition of the present invention, the secondary battery can exhibit excellent high-temperature storage characteristics.

[0234] <Electrode Manufacturing Method>

[0235] The method for producing the electrode of the present invention is not particularly limited, and the electrode of the present invention can be produced by, for example, forming a functional layer on the above-mentioned electrode substrate.

[0236] Here, as a method for producing the electrode of the present invention by forming a functional layer on an electrode substrate, for example, the following method can be mentioned.

[0237] 1) A method of supplying the binder composition or slurry composition of the present invention to the surface of an electrode substrate (the surface on the electrode composite material layer side, the same below) and then drying it; and

[0238] 2) A method in which the adhesive composition or slurry composition of the present invention is supplied onto a release substrate and dried to produce a functional layer, and the obtained functional layer is transferred to the surface of an electrode substrate.

[0239] Among these, method 1) is particularly preferred because it allows for easy control of the thickness of the functional layer. Specifically, method 1) includes: supplying a binder composition or slurry composition onto an electrode substrate (supplying step); and drying the binder composition or slurry composition applied to the electrode substrate to form the functional layer (drying step).

[0240] The supply process and drying process can be the same as those described in the "Method for Manufacturing a Separator" section. Furthermore, from the perspective of ensuring the strength of the functional layer while improving the battery characteristics of the secondary battery, the thickness of the functional layer formed on the electrode substrate as described above is preferably not less than 0.1 μm and not more than 10 μm.

[0241] (Non-aqueous secondary battery)

[0242] The non-aqueous secondary battery of the present invention comprises at least a positive electrode, a negative electrode, a separator, and an electrolyte. Furthermore, the non-aqueous secondary battery of the present invention satisfies one or both of the following requirements (I) and (II):

[0243] (I) The spacer is the spacer of the present invention described above;

[0244] (II) At least one of the positive electrode and the negative electrode is the electrode of the present invention.

[0245] <Spacer>

[0246] As a separator, the separator of the present invention described above can be used. In addition, when at least one of the positive electrode and the negative electrode is an electrode of the present invention, a known separator other than the separator of the present invention can be used as a separator. As a known separator other than the separator of the present invention, a separator formed of a separator substrate described in the above-mentioned "Separator for non-aqueous secondary batteries" can be cited.

[0247] Electrodes

[0248] As the positive electrode and the negative electrode, the electrode of the present invention described above can be used. In addition, when the separator or another electrode is the separator of the present invention or the electrode of the present invention, as the positive electrode and the negative electrode, known electrodes other than the electrode of the present invention can be used. As known electrodes other than the electrode of the present invention, electrodes formed by the electrode base materials described in the above-mentioned "electrode for non-aqueous secondary batteries" item can be cited.

[0249] Electrolyte

[0250] As the electrolyte, an organic electrolyte in which a supporting electrolyte is dissolved in an organic solvent is generally used. As the supporting electrolyte, a lithium salt can be used, for example, in a lithium ion secondary battery. Examples of lithium salts include LiPF6, LiAsF6, LiBF4, LiSbF6, LiAlCl4, LiClO4, CF3SO3Li, C4F9SO3Li, CF3COOLi, (CF3CO)2NLi, (CF3SO2)2NLi, (C2F5SO2)NLi, etc. Among them, LiPF6, LiClO4, and CF3SO3Li are preferred because they are easily soluble in solvents and exhibit a high degree of dissociation. In addition, one electrolyte can be used alone or in combination of two or more. Generally, there is a tendency that the higher the degree of dissociation of the supporting electrolyte, the higher the lithium ion conductivity. Therefore, the lithium ion conductivity can be adjusted according to the type of supporting electrolyte.

[0251] Organic solvents used in electrolytes are not particularly limited as long as they can dissolve the supporting electrolyte. For example, in lithium-ion secondary batteries, preferred examples include carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), and ethyl methyl carbonate (EMC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; and sulfur-containing compounds such as sulfolane and dimethyl sulfoxide. Mixtures of these solvents can also be used. Carbonates are preferred due to their high dielectric constant and wide stable potential range. Generally, the lower the viscosity of the solvent used, the higher the lithium ion conductivity. Therefore, the lithium ion conductivity can be adjusted by the type of solvent.

[0252] The concentration of the electrolyte in the electrolytic solution can be adjusted appropriately. In addition, known additives can be added to the electrolytic solution.

[0253] (Method for Manufacturing Non-Aqueous Secondary Battery)

[0254] The non-aqueous secondary battery of the present invention can be manufactured, for example, by overlapping the positive and negative electrodes with a separator, winding or folding the electrodes as needed, placing the electrodes in a battery container, injecting an electrolyte into the battery container, and sealing the container. Furthermore, at least one of the positive, negative, and separator components can be formed into a component having a functional layer. Furthermore, as needed, the battery container can contain metal mesh, fuses, PTC components, and other overcurrent protection elements, as well as guide plates, to prevent internal pressure buildup and overcharge and discharge. The battery can be in any of the following shapes, for example, coin-shaped, button-shaped, sheet-shaped, cylindrical, square, and flat.

[0255] Example

[0256] Hereinafter, the present invention will be described in detail based on Examples, but the present invention is not limited to these Examples. In the following description, "%" and "parts" showing amounts are based on mass unless otherwise specified.

[0257] In addition, in a polymer produced by copolymerizing multiple monomers, unless otherwise specified, the ratio of monomer units formed by polymerizing a certain monomer in the above polymer is usually consistent with the ratio (charging ratio) of the certain monomer in all monomers used in the polymerization of the polymer.

[0258] In the examples and comparative examples, the volume average particle size of the granular polymer, the electrolyte swelling degree of the granular polymer, the glossiness of the coating film, the pH of the aqueous dispersion and the adhesive composition during pickling, the dispersion stability of the adhesive composition, the amount of coagulants in the slurry composition, the dry adhesion of the functional layer, and the high-temperature storage characteristics of the secondary battery were measured or evaluated by the following methods.

[0259] <Volume average particle size D50 of granular polymer A>

[0260] The dried particulate polymer A prepared in the Examples and Comparative Examples was added to 400 parts of ion-exchanged water and re-slurried to obtain an aqueous dispersion, which was used as a measurement sample. 0.1 g of the measurement sample, equivalent to the solid content, was weighed into a beaker, and 0.1 mL of an aqueous solution of alkylbenzenesulfonic acid (manufactured by Fujifilm Corporation, "DRIWEL") was added as a dispersant. 10 to 30 mL of a diluent (manufactured by Beckman Coulter, "ISOTON II") was further added to the beaker, and the mixture was dispersed for 3 minutes using a 20W ultrasonic disperser. The volume-based average particle size D50 of the measurement sample was then measured using a particle size analyzer (manufactured by Beckman Coulter, "Multisizer") under the conditions of a 20 μm aperture, an ISOTON II medium, and 100,000 particles.

[0261] <Volume average particle size D50 of granular polymer B>

[0262] The volume average particle diameter D50 of the particulate polymer B prepared in the Examples and Comparative Examples was measured using a laser diffraction method. Specifically, an aqueous dispersion of the particulate polymer B prepared in the Examples and Comparative Examples (adjusted to a solids concentration of 0.1% by mass) was used as a sample. Furthermore, the volume average particle diameter was defined as the particle diameter D50 at which the cumulative volume, calculated from the smaller diameter side, reached 50% in the particle size distribution (volume basis), as measured using a laser diffraction particle size distribution analyzer (manufactured by Beckman Coulter, "LS-230").

[0263] <Electrolyte swelling>

[0264] The dried granular polymer A prepared in the Examples and Comparative Examples was used as the test sample. Approximately 0.2 g of the sample was pressed at 200°C and 5 MPa for two minutes to form a film. The resulting film was then cut into 1 cm squares to form test pieces. The mass W0 of each test piece was measured.

[0265] In addition, the above-mentioned test piece was immersed in an electrolyte at 60°C for 72 hours. After that, the test piece was taken out from the electrolyte, the electrolyte on the surface of the test piece was wiped off, and the mass W1 of the test piece after the immersion test was measured. Using the measured masses W0 and W1, the electrolyte swelling degree S (times) was calculated by S=W1 / W0. In addition, as the electrolyte, a solution obtained by dissolving LiPF6 as a supporting electrolyte at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC) and vinylene carbonate (VC) (volume ratio: EC / DEC / VC=68.5 / 30 / 1.5) was used.

[0266] <Glossiness of coating film>

[0267] The adhesive composition prepared in the examples and comparative examples was stirred at 2000 rpm for 1 minute using a rotation-revolution mixer. Then, the adhesive composition was applied to a spacer substrate (a polyethylene spacer substrate, manufactured by Asahi Kasei Corporation, product name "ND412", thickness 12 μm) using a rod coater at a coating speed of 50 mm / min, and then dried at 80°C. The 86° gloss and 60° gloss of the obtained coating were measured using a gloss device (MULTIGLOSS 268A, manufactured by Konica Minolta) in accordance with JIS Z 8741. In addition, the ratio of the 86° gloss to the 60° gloss was determined. The results are shown in Table 1. In addition, the unit area mass (mg / cm 2 ) as shown in Table 1.

[0268] <Dispersion stability of adhesive composition>

[0269] The adhesive composition prepared in the examples and comparative examples was stirred at 2000 rpm for 1 minute using a rotation-revolution mixer. The initial particle size distribution was determined by the method described in <Volume average particle size D50 of granular polymer A>. Next, 400 mL of the stirred adhesive composition was filled into a 500 mL container and centrifuged at a speed equivalent to 9000 G for 30 minutes. For the adhesive composition after centrifugation, the initial particle size distribution was determined by the method described in <Volume average particle size D50 of granular polymer A>. Then, the change rate of the volume average particle size D50 before and after centrifugation was calculated according to the following formula. Then, the dispersion stability was evaluated according to the following criteria. The results are shown in Table 1. The closer the change rate of D50 is to 1, the better the dispersion stability is, and the further away from 1, the worse the dispersion stability is.

[0270] Change rate of D50 = D50 after centrifugation / D50 before centrifugation

[0271] A: The rate of change of D50 is less than 2

[0272] B: The change rate of D50 is 2 or more and less than 3

[0273] C: The change rate of D50 is 3 or more and less than 4

[0274] D: The change rate of D50 is 4 or more

[0275] pH

[0276] The pH of the aqueous dispersion of the particulate polymer during acid washing and the pH of the binder composition were measured at room temperature (25° C.) using a tabletop pH meter “F-72S” manufactured by Horiba, Ltd.

[0277] Adhesion before electrolyte immersion (dry adhesion)

[0278] The negative electrode and the separator with a functional layer prepared in the examples and comparative examples (the negative electrode and separator with a functional layer in Example 2) were cut into pieces with a width of 10 mm and a length of 50 mm, respectively, and the negative electrode and the separator were stacked and pressed for 10 seconds using a flat press at a temperature of 70°C and a load of 0.5 kN to obtain a test piece. For the test piece, the collector side of the negative electrode was facing down, and a transparent tape was pasted on the surface of the negative electrode. At this time, the transparent tape specified in JIS Z1522 was used as the transparent tape. In addition, the transparent tape was pre-fixed on a horizontal test bench. Then, one end of the separator was stretched vertically upward at a tensile speed of 50 mm / min to peel it off to measure the stress during peeling. The stress measurement was carried out 3 times in total. The average value of the stress obtained for a total of 3 times was calculated as the peel strength (N / m), and the adhesion (dry adhesion) between the negative electrode and the separator separated by the functional layer was evaluated using the following benchmark. The greater the peel strength, the better the dry adhesion.

[0279] A: Peel strength is 5.0 N / m or more

[0280] B: Peel strength is 3.0 N / m or more and less than 5.0 N / m

[0281] C: Peel strength is 1.0 N / m or more and less than 3.0 N / m

[0282] D: Peel strength less than 1.0N / m

[0283] <High-temperature storage characteristics>

[0284] After the lithium-ion secondary batteries prepared in the examples and comparative examples were injected with electrolyte, they were left to stand at a temperature of 25°C for 5 hours. Next, they were charged at a temperature of 25°C with a constant current method of 0.2C to a battery cell voltage of 3.65V, and then aged at a temperature of 60°C for 12 hours. Then, they were discharged at a constant current method of 0.2C to a battery cell voltage of 3.00V at a temperature of 25°C. Thereafter, CC-CV charging was performed at a constant current method of 0.2C (upper limit battery cell voltage 4.40V), and CC discharge was performed at a constant current method of 0.2C to 3.00V. This 0.2C charge and discharge was repeated 3 times.

[0285] Afterwards, in an environment with a temperature of 25°C, charge with a constant current method of 0.2C until the battery cell voltage reaches 4.40V, and continue charging until the current value after the battery cell voltage reaches 4.40V becomes 0.02C. Next, remove it from the charge and discharge control device and store it at 60°C for 4 weeks. After storage, cool it to 25°C, discharge it to 3.0V using a constant current method of 0.2C, and then charge it until the charging rate reaches 50% (that is, if the battery cell capacity is 800mAh, charge it to a charging capacity of 400mAh), and measure the voltage change in the following steps (1) to (3). Then, the resistance value after constant temperature storage is obtained by the following formula. The lower the resistance value after constant temperature storage, the better the high-temperature storage characteristics of the secondary battery.

[0286] (1) Calculate the voltage change ΔV(0.2) when discharging for 30 seconds using the 0.2C constant current method (I0.2).

[0287] (2) Charge at 0.2C constant current for 30 seconds

[0288] (3) Calculate the voltage change ΔV(1.0) when discharging for 30 seconds using the 1.0 C constant current method (I1.0).

[0289] Resistance (Ω) = {ΔV(1.0) - ΔV(0.2)} / (I1.0 - I0.2)

[0290] A: The resistance value after high temperature storage test is less than 2.9Ω

[0291] B: The resistance value after the high-temperature storage test is 2.9Ω or more and less than 3.1Ω

[0292] C: The resistance value after the high-temperature storage test is 3.1Ω or more and less than 3.3Ω

[0293] D: The resistance value after the high temperature storage test is 3.3Ω or more

[0294] (Example 1)

[0295] <Preparation of Granular Polymer A>

[0296] [Preparation of Monomer Composition (A)]

[0297] 65 parts of styrene as an aromatic monovinyl monomer, 24.5 parts of n-butyl acrylate as a (meth)acrylate monomer, 0.5 parts of ethylene glycol dimethacrylate as a crosslinking monomer, and 10 parts of glycidyl methacrylate as an epoxy group-containing unsaturated monomer were mixed to prepare a monomer composition (A).

[0298] [Preparation of Metal Hydroxides]

[0299] To an aqueous solution (A1) obtained by dissolving 10.0 parts of magnesium chloride in 200 parts of ion-exchanged water, an aqueous solution (A2) obtained by dissolving 7.0 parts of sodium hydroxide in 50 parts of ion-exchanged water was slowly added with stirring to prepare a colloidal dispersion (A) containing magnesium hydroxide as a metal hydroxide.

[0300] [Suspension polymerization method]

[0301] Particulate polymer A was prepared by suspension polymerization. Specifically, the monomer composition (A) obtained as described above was added to the colloidal dispersion containing magnesium hydroxide, and after further stirring, 3.0 parts of tert-butyl peroxy-2-ethylhexanoate (manufactured by NOF Corporation, "PERBUTYL O") was added as a polymerization initiator to obtain a mixed solution. The obtained mixed solution was subjected to high-shear stirring at a rotation speed of 12,000 rpm for 1 minute using an inline emulsifier disperser (manufactured by Pacific Machinery Co., Ltd., "CAVITRON") to form droplets of the monomer composition (A) in the colloidal dispersion containing magnesium hydroxide.

[0302] A colloidal dispersion containing magnesium hydroxide and containing droplets of the monomer composition (A) was placed in a reactor, heated to 90°C, and subjected to a polymerization reaction for 5 hours. The resulting dispersion was purified by decompression treatment at 90°C for 2 hours using an evaporator to obtain an aqueous dispersion containing particulate polymer A.

[0303] Furthermore, while stirring the aqueous dispersion containing the particulate polymer A, sulfuric acid was added dropwise at room temperature (25°C) until the pH reached 5.5. Stirring was continued for 5 hours, followed by acid washing. The dispersion was then filtered and separated, and 500 parts of ion-exchanged water was added to the resulting solids to form a reslurry. The slurry was then washed (washed, filtered, and dehydrated) until the conductivity reached 0.1 mS / cm or less. The resulting solids were then filtered and separated, placed in a desiccator, and dried at 40°C for 48 hours to obtain dried particulate polymer A.

[0304] Then, the volume average particle size and the degree of swelling in the electrolyte solution of the particulate polymer A were measured. The results are shown in Table 1.

[0305] <Preparation of Granular Polymer B>

[0306] Into a reactor equipped with a stirrer, 70 parts of ion-exchanged water, 0.15 parts of sodium lauryl sulfate ("Emal (registered trademark) 2F" manufactured by Kao Chemical Co., Ltd.) as an emulsifier, and 0.5 parts of ammonium persulfate as a polymerization initiator were supplied, the gas phase was replaced with nitrogen, and the temperature was raised to 60°C.

[0307] On the other hand, in another container, 50 parts of ion-exchanged water, 0.5 parts of sodium dodecylbenzenesulfonate as a dispersion stabilizer, 94 parts of n-butyl acrylate as a (meth)acrylate monomer, 2 parts of methacrylic acid as an acidic group-containing monomer, 2 parts of acrylonitrile as a nitrile group-containing monomer, 1 part of allyl methacrylate as a crosslinking monomer, and 1 part of allyl glycidyl ether as an epoxy group-containing unsaturated monomer were mixed to prepare a monomer composition (B).

[0308] The resulting monomer composition (B) was continuously added to the above-mentioned reactor equipped with a stirrer over a period of 4 hours for polymerization. During the addition process, the reaction was carried out at 60°C. After the addition was completed, the reaction was further stirred at 70°C for 3 hours, after which the reaction was terminated to obtain an aqueous dispersion containing particulate polymer B having a solids concentration of 45% by mass. The pH of the aqueous dispersion containing particulate polymer B was 3.8. The volume average particle size of the particulate polymer B was then measured. The results are shown in Table 1.

[0309] <Preparation of Adhesive Composition>

[0310] 80 parts by mass of granular polymer A and 0.5 parts of polyacrylic acid as a dispersant were added, followed by ion-exchanged water to a solids concentration of 20%. 0.2 parts of sodium dodecylbenzenesulfonate ("NEOPELEX G-15," manufactured by Kao Chemical Co., Ltd.) as an emulsifier and 1.5 parts of carboxymethyl cellulose as a water-soluble polymer were mixed to a solids concentration of 40%. 0.5 parts of 1,2-benzo-4-isothiazolin-3-one as a preservative were then added. The resulting mixture was mixed using a ball mill. Next, the mixture containing granular polymer A was added to a container equipped with a stirrer, followed by 20 parts by mass of an aqueous dispersion containing granular polymer B, based on the solids content, and mixed for 1 hour. The pH was then adjusted to 8.0 using a 4% aqueous sodium hydroxide solution, and then adjusted to a solids concentration of 20% using ion-exchanged water to obtain an adhesive composition. This adhesive composition was used to measure dispersion stability and the gloss of the coating film. The results are shown in Table 1.

[0311] <Preparation of slurry composition>

[0312] To the above binder composition (100 parts by mass based on solid content), 300 parts of alumina (AKP3000, manufactured by Sumitomo Chemical Co., Ltd., volume average particle size: 0.7 μm) as inorganic particles were added and mixed using a ball mill. Ion-exchanged water was then added to a solid content concentration of 25% by mass to obtain a slurry composition.

[0313] <Production of spacers with functional layers>

[0314] Prepare a polyethylene spacer substrate (thickness: 12 μm) as a spacer substrate. Apply the slurry composition obtained as described above to one side of the spacer substrate by bar coating. Next, dry the spacer substrate coated with the slurry composition at 50°C for 1 minute to form a functional layer. Perform the same operation on the other side of the spacer substrate to produce a spacer with a functional layer having a functional layer with a thickness of 2.0 μm on each side of the spacer substrate.

[0315] <Making the positive electrode>

[0316] 100 parts of LiCoO2 (volume average particle size: 12 μm) as a positive electrode active material, 2 parts of acetylene black ("HS-100" manufactured by Denka Co., Ltd.) as a conductive material, 2 parts of polyvinylidene fluoride ("#7208" manufactured by Kureha Co., Ltd.) as a binder for the positive electrode composite material layer, and N-methylpyrrolidone as a solvent were mixed to a total solid content concentration of 70%. These were mixed using a planetary mixer to prepare a positive electrode slurry composition.

[0317] The above-mentioned positive electrode slurry composition is applied to an aluminum foil with a thickness of 20 μm as a current collector using a notch wheel coater so that the film thickness after drying is about 150 μm and dried. The drying is carried out by transporting the aluminum foil at a speed of 0.5 m / min in an oven at 60 ° C for 2 minutes. Afterwards, the positive electrode raw material before pressing is obtained by heat treatment at 120 ° C for 2 minutes. The positive electrode raw material before pressing is rolled using a roller press to obtain a pressed positive electrode having a positive electrode composite material layer (thickness: 60 μm).

[0318] <Production of the negative electrode>

[0319] In a 5 MPa pressure-resistant container equipped with a stirrer, 33 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 63.5 parts of styrene, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator were placed. After thorough stirring, the mixture was heated to 50°C to initiate polymerization. When the polymerization conversion reached 96%, the reaction was terminated by cooling to obtain a mixture containing a binder material (SBR) for the negative electrode composite material layer. A 5% aqueous sodium hydroxide solution was added to this mixture containing the binder material for the negative electrode composite material layer, and after adjusting the pH to 8, unreacted monomers were removed by heating and reduced pressure distillation. The mixture was then cooled to below 30°C to obtain an aqueous dispersion containing the desired binder material for the negative electrode composite material layer.

[0320] 80 parts of artificial graphite (volume average particle size: 15.6 μm) as the negative electrode active material (1) and 16 parts of silicon-based active material SiOx (volume average particle size: 4.9 μm) as the negative electrode active material (2) were mixed with 2.5 parts of a 2% aqueous solution of sodium carboxymethylcellulose (manufactured by Nippon Paper Industries, Ltd., "MAC350HC") as a viscosity modifier and ion-exchanged water, adjusted to a solid content concentration of 68%, and then further mixed at 25°C for 60 minutes. Furthermore, after adjusting the solid content concentration to 62% with ion-exchanged water, the mixture was further mixed at 25°C for 15 minutes to obtain a mixed solution. 1.5 parts of an aqueous dispersion containing the binder material for the negative electrode composite material layer and ion-exchanged water were added to the mixed solution, adjusted to a final solid content concentration of 52%, and further mixed for 10 minutes to obtain a mixed solution. The mixed solution was degassed under reduced pressure to obtain a negative electrode slurry composition with good fluidity.

[0321] The negative electrode slurry composition is applied to a copper foil with a thickness of 20 μm as a current collector using a notch wheel coater so that the film thickness after drying is about 150 μm and dried. The drying is carried out by transporting the copper foil at a speed of 0.5 m / min in an oven at 60 ° C for 2 minutes. Afterwards, the negative electrode raw material before pressing is obtained by heat treatment at 120 ° C for 2 minutes. The negative electrode raw material before pressing is rolled using a roller press to obtain a pressed negative electrode having a negative electrode composite material layer (thickness: 80 μm).

[0322] The dry adhesion of the functional layer was evaluated using the separator with a functional layer and the negative electrode obtained as described above. The results are shown in Table 1.

[0323] Production of lithium-ion secondary batteries

[0324] The pressed positive electrode prepared as described above is cut into a rectangle of 49 cm × 5 cm and placed so that the surface of the positive electrode composite material layer side is on the upper side. The above-mentioned functional layer separator cut into 120 cm × 5.5 cm is arranged on the positive electrode composite material layer so that the positive electrode is located on one side of the longitudinal direction of the functional layer separator. Furthermore, the pressed negative electrode prepared as described above is cut into a rectangle of 50 cm × 5.2 cm and is arranged on the functional layer separator so that the surface of the negative electrode composite material layer side is opposite to the functional layer separator and the negative electrode is located on the other side of the longitudinal direction of the functional layer separator. Then, the obtained material is wound by a winding machine to obtain a wound body. The wound body is pressed at 70 ° C and 1 MPa to form a flat body, and then wrapped with an aluminum packaging material outer packaging as the outer packaging of the battery, and the electrolyte [solvent: ethylene carbonate / diethyl carbonate / vinylene carbonate (volume ratio) = 68.5 / 30 / 1.5, electrolyte: LiPF6 with a concentration of 1M)] is injected in a way that no air remains. Then, the opening of the outer packaging of the aluminum packaging material was heat-sealed at a temperature of 150° C. to prepare a wound-type lithium-ion secondary battery with a capacity of 800 mAh.

[0325] The obtained lithium ion secondary battery was used to evaluate the high-temperature storage characteristics of the secondary battery. The results are shown in Table 1.

[0326] (Example 2)

[0327] In Example 1, the slurry composition was applied to the negative electrode composite material layer of the negative electrode obtained and dried at 100°C for 1 minute to produce a negative electrode having a functional layer (a negative electrode with a functional layer). In addition, a separator without a functional layer was used. The same procedures as in Example 1 were followed, except that particulate polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, and a lithium-ion secondary battery were prepared or manufactured, and the same items were evaluated. The results are shown in Table 1.

[0328] (Example 3)

[0329] In Example 1, except that the pH of the aqueous dispersion containing the particulate polymer A during acid washing was changed to 6.0, the same procedures as in Example 1 were followed to prepare or manufacture particulate polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery, and the same items were evaluated. The results are shown in Table 1.

[0330] (Example 4)

[0331] In Example 1, except that the pH of the aqueous dispersion containing the particulate polymer A during acid washing was changed to 6.5, the same procedures as in Example 1 were followed to prepare or manufacture particulate polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery, and the same items were evaluated. The results are shown in Table 1.

[0332] (Example 5)

[0333] Particulate polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery were prepared or manufactured in the same manner as in Example 1, except that the pH of the binder composition was changed to 7.6. The same items were evaluated. The results are shown in Table 1.

[0334] (Example 6)

[0335] In Example 1, except that the pH of the binder composition was changed to 8.8, the same procedures as in Example 1 were followed to prepare or manufacture particulate polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery. The same items were evaluated. The results are shown in Table 1.

[0336] (Example 7)

[0337] In Example 1, except that the amount of magnesium chloride used in preparing granular polymer A was changed from 10.0 parts to 8.0 parts, and the pH of the binder composition was changed to 8.8, the same procedures as in Example 1 were followed to prepare or manufacture granular polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery, and the same items were evaluated. The results are shown in Table 1.

[0338] (Example 8)

[0339] In Example 1, except that the amounts of monomers used in preparing the granular polymer A were changed to those shown in Table 1, the same procedures as in Example 1 were followed to prepare or manufacture granular polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery, and the same items were evaluated. The results are shown in Table 1.

[0340] (Example 9)

[0341] In Example 1, except that the amounts of monomers used in preparing the granular polymer A were changed to those shown in Table 1, the same procedures as in Example 1 were followed to prepare or manufacture granular polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery, and the same items were evaluated. The results are shown in Table 1.

[0342] (Examples 10 to 13)

[0343] In Example 1, except that the amounts of monomers used in preparing granular polymer A were changed to those shown in Table 1, acid washing was not performed, and the pH of the binder composition was changed to 9.9, granular polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery were prepared or manufactured in the same manner as in Example 1, and the same items were evaluated. The results are shown in Table 1.

[0344] (Comparative Example 1)

[0345] In Example 1, except that the pH of the aqueous dispersion containing the particulate polymer A during acid washing was changed to 6.5, and the acid washing time during preparation of the particulate polymer A was changed from 5 hours to 0.25 hours, the same procedures as in Example 1 were followed to prepare or manufacture particulate polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery, and the same items were evaluated. The results are shown in Table 1.

[0346] (Comparative Example 2)

[0347] Particulate polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery were prepared or manufactured in the same manner as in Example 1, except that the pH of the binder composition was changed to 7.0. The same items were evaluated. The results are shown in Table 1.

[0348] (Comparative Example 3)

[0349] In Example 1, except that the pH of the binder composition was changed to 9.7, the same procedures as in Example 1 were followed to prepare or manufacture particulate polymers A and B, a binder composition, a slurry composition, a positive electrode, a negative electrode, a separator with a functional layer, and a lithium-ion secondary battery. The same items were evaluated. The results are shown in Table 1.

[0350] [Table 1]

[0351]

[0352] In Table 1,

[0353] "ST" represents styrene units,

[0354] "EDMA" represents ethylene glycol dimethacrylate units,

[0355] "BA" represents n-butyl acrylate units,

[0356] "MMA" means methyl methacrylate units,

[0357] "GMA" means glycidyl methacrylate units,

[0358] "MAA" means methacrylic acid units,

[0359] "AN" represents acrylonitrile unit,

[0360] "AMA" means allyl methacrylate units.

[0361] As shown in the results in Table 1, in Examples 1 to 13 using an adhesive composition having a coating film having an 86° gloss of 1 or more and 70 or less and a 60° gloss of less than 6 when applied and dried on a polyethylene separator substrate, the adhesive composition has excellent dispersion stability and the resulting secondary batteries exhibit excellent high-temperature storage characteristics.

[0362] Industrial applicability

[0363] According to the present invention, a binder composition for a non-aqueous secondary battery functional layer can be provided which has excellent dispersion stability and can form a functional layer capable of improving the high-temperature storage characteristics of a secondary battery.

[0364] Furthermore, according to the present invention, it is possible to provide a slurry composition for a non-aqueous secondary battery functional layer capable of forming a functional layer capable of improving the high-temperature storage characteristics of a secondary battery.

[0365] Furthermore, according to the present invention, a separator for a non-aqueous secondary battery and an electrode for a non-aqueous secondary battery capable of improving the high-temperature storage characteristics of a secondary battery can be provided.

[0366] Furthermore, according to the present invention, a non-aqueous secondary battery having excellent high-temperature storage characteristics can be provided.

Claims

1. A binder composition for a non-aqueous secondary battery functional layer, comprising a granular polymer A, a granular polymer B different from the granular polymer A, and a dispersion medium. The adhesive composition for a non-aqueous secondary battery functional layer is applied onto a polyethylene separator substrate and dried to obtain a coating film having an 86° glossiness of 1 or more and 70 or less and a 60° glossiness of less than 6.

2. The binder composition for a non-aqueous secondary battery functional layer according to claim 1, wherein The coating film has a ratio of 86° glossiness to 60° glossiness (86° glossiness / 60° glossiness) of 1 or more and 50 or less.

3. The binder composition for a non-aqueous secondary battery functional layer according to claim 1, wherein The dispersion medium is water, and the pH of the non-aqueous secondary battery functional layer binder composition is greater than 7.5 and less than 9.

0.

4. The binder composition for a non-aqueous secondary battery functional layer according to claim 1, wherein The mass ratio of the granular polymer A to the granular polymer B (granular polymer A:granular polymer B) is 50:50 or more and 95:5 or less.

5. The binder composition for a non-aqueous secondary battery functional layer according to claim 1, wherein The volume average particle diameter D50 of the particulate polymer A is 0.5 μm or more and 10 μm or less.

6. The binder composition for a non-aqueous secondary battery functional layer according to claim 1, wherein The electrolyte swelling degree of the particulate polymer A is 1 to 5 times.

7. The binder composition for a non-aqueous secondary battery functional layer according to claim 1, wherein The granular polymer A contains 25% by mass or more of aromatic vinyl monomer units. 8 . A slurry composition for a non-aqueous secondary battery functional layer, comprising inorganic particles and the binder composition for a non-aqueous secondary battery functional layer according to claim 1 .

9. The slurry composition for a non-aqueous secondary battery functional layer according to claim 8, wherein The volume average particle diameter D50 of the inorganic particles is 0.1 μm or more and 1.0 μm or less.

10. A separator for a non-aqueous secondary battery comprising a separator substrate and a functional layer provided on at least one surface of the separator substrate. The functional layer is formed using the binder composition for a non-aqueous secondary battery functional layer according to any one of claims 1 to 7 or the slurry composition for a non-aqueous secondary battery functional layer according to claim 8 or 9.

11. An electrode for a non-aqueous secondary battery, comprising an electrode substrate and a functional layer provided on at least one surface of the electrode substrate. The functional layer is formed using the binder composition for a non-aqueous secondary battery functional layer according to any one of claims 1 to 7 or the slurry composition for a non-aqueous secondary battery functional layer according to claim 8 or 9.

12. A non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte. The separator is the separator for a non-aqueous secondary battery according to claim 10 .

13. A non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte. At least one of the positive electrode and the negative electrode is the electrode for a non-aqueous secondary battery according to claim 11.

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