Binder composition for functional layer of electrochemical element, slurry composition for functional layer of electrochemical element, laminate for electrochemical element, and electrochemical element

Abstract

The purpose of the present invention is to provide an adhesive composition for a functional layer of an electrochemical element, said adhesive composition having excellent redispersibility after long-term storage and being capable of causing the functional layer to exhibit excellent adhesiveness. The present invention is a binder composition for a functional layer of an electrochemical element, the binder composition comprising a particulate polymer, a water-soluble polymer, and water, the particulate polymer having a volume particle diameter (D50) of 1.0-15.0 [mu] m and a true specific gravity of 1.00-2.00.

Description

Technical Field

[0001] The present invention relates to an adhesive composition for an electrochemical device functional layer, a slurry composition for an electrochemical device functional layer, a laminate for an electrochemical device, and an electrochemical device. Background Art

[0002] Electrochemical devices such as lithium-ion secondary batteries and electric double-layer capacitors are compact, lightweight, have high energy density, and are capable of repeated charge and discharge, making them widely used. Electrochemical devices typically include 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 electrochemical elements such as lithium-ion secondary batteries, it is possible to use battery components having a heat-resistant layer for improving heat resistance, an adhesive layer for bonding battery components to each other, etc. (hereinafter collectively referred to as "functional layer"). Specifically, an electrode in which a functional layer is further formed on an electrode substrate, and a separator in which a functional layer is formed on a separator substrate are used as battery components, and the above-mentioned electrode substrate is formed by arranging the above-mentioned electrode composite material layer on a current collector. Moreover, in recent years, with the purpose of further improving the performance of electrochemical elements such as lithium-ion secondary batteries, further improvements of the functional layer are being studied.

[0004] For example, Patent Document 1 proposes forming a functional layer capable of exhibiting excellent adhesiveness by adding a particulate polymer having an average circularity of 0.90 to less than 0.99 and a volume average particle size of 1.0 μm to 10.0 μm to a composition for an electrochemical device functional layer.

[0005] In addition, in Patent Document 2, the following is proposed: In order to form a functional layer that takes into account both the property of bonding components to each other (process adhesion) and the property of suppressing unexpected adhesion (adhesion) to other components (anti-adhesion) at a sufficiently high level in the manufacturing process of the electrochemical element, a granular polymer is added to the composition for the functional layer of the electrochemical element, and the above-mentioned granular polymer includes a polymer A containing a (meth)acrylate monomer unit and an acidic group-containing monomer unit and a polymer B having a different composition from polymer A, and the volume average particle size is greater than 1.0 μm and is less than 10.0 μm.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: International Publication No. 2020 / 175292;

[0009] Patent document 2: International Publication No. 2022 / 163780. Summary of the Invention

[0010] Problems to be solved by the invention

[0011] Here, if the binder composition for an electrochemical device functional layer containing a particulate polymer is stored for a long period of time, the particulate polymer may precipitate, and it is desirable that the particulate polymer be quickly redispersed when the composition is stirred.

[0012] Furthermore, it is desired that the functional layer formed using the adhesive composition for an electrochemical device functional layer has excellent adhesion to the battery member.

[0013] However, conventional electrochemical element functional layer compositions have room for improvement in terms of excellent redispersibility after long-term storage and excellent adhesiveness of the functional layer.

[0014] Therefore, an object of the present invention is to provide a binder composition for a functional layer of an electrochemical device that has excellent redispersibility after long-term storage and can enable the functional layer to exhibit excellent adhesiveness.

[0015] Another object of the present invention is to provide a slurry composition for an electrochemical device functional layer using the binder composition for an electrochemical device functional layer of the present invention.

[0016] Another object of the present invention is to provide a laminate for an electrochemical device having a functional layer formed using the above-mentioned binder composition for an electrochemical device functional layer or the above-mentioned slurry composition for an electrochemical device functional layer.

[0017] Another object of the present invention is to provide an electrochemical device including the above-mentioned electrochemical device laminate.

[0018] Solutions for solving problems

[0019] The present inventors conducted intensive research to achieve the above-mentioned objectives. They subsequently discovered that a binder composition for a functional layer of an electrochemical device comprising a particulate polymer having a predetermined volume particle size D50 and a predetermined true specific gravity, a water-soluble polymer, and water can solve the above-mentioned problems, thereby completing the present invention.

[0020] That is, the present invention aims to advantageously solve the above-mentioned problems. [1] The present invention is an adhesive composition for a functional layer of an electrochemical element, which comprises a granular polymer, a water-soluble polymer and water, wherein the volume particle size D50 of the granular polymer is greater than or equal to 1.0 μm and less than or equal to 15.0 μm, and the true specific gravity is greater than or equal to 1.00 and less than or equal to 2.00.

[0021] The binder composition for an electrochemical device functional layer as described above exhibits excellent redispersibility after long-term storage (hereinafter sometimes referred to as "long-term redispersibility") and enables the functional layer to exhibit excellent adhesive properties. In this specification, "long-term" generally refers to 5 days or more, preferably 10 days or more, more preferably 30 days or more, and even more preferably 90 days or more.

[0022] In this specification, the volume particle size D50 of the particulate polymer refers to the particle size at which the cumulative volume calculated from the smaller particle size side accounts for 50% in the particle size distribution (volume basis) measured using a particle size distribution analyzer, and can be measured by the method described in Examples.

[0023] In this specification, the true specific gravity of a granular polymer can be measured using a pycnometer method in accordance with JIS Z8837.

[0024] In this specification, a water-soluble polymer is a polymer having a solubility in water at 25° C. of 1 g / L or more.

[0025] [2] In the binder composition for an electrochemical device functional layer according to [1] above, the water-soluble polymer preferably has a weight average molecular weight of 80,000 or more and 500,000 or less.

[0026] If the weight-average molecular weight of the water-soluble polymer is within the above range, the long-term redispersibility of the adhesive composition for the electrochemical element functional layer and the aggregation inhibition of the adhesive composition for the electrochemical element functional layer after long-term storage (hereinafter sometimes referred to as "long-term aggregation inhibition") can be improved.

[0027] In this specification, the weight average molecular weight can be measured by the method described in Examples.

[0028] [3] In the binder composition for an electrochemical device functional layer according to [1] above, the water-soluble polymer preferably has a weight average molecular weight of 5,000 or more and 200,000 or less.

[0029] When the weight average molecular weight of the water-soluble polymer is within the above range, the long-term redispersibility of the binder composition for an electrochemical device functional layer can be improved.

[0030] [4] In the binder composition for an electrochemical device functional layer according to any one of [1] to [3] above, the water-soluble polymer preferably has an acid group.

[0031] When the water-soluble polymer has an acid group, the long-term redispersibility of the binder composition for an electrochemical device functional layer can be improved.

[0032] [5] In the adhesive composition for an electrochemical device functional layer according to any one of [1] to [4] above, the pH is preferably 6.0 or higher and 12.0 or lower.

[0033] When the pH of the binder composition for an electrochemical element functional layer is within the above range, aggregation of solid components such as particulate polymers contained in the binder composition for an electrochemical element functional layer can be suppressed, thereby improving coating stability.

[0034] In this specification, the pH of the adhesive composition for an electrochemical device functional layer can be measured by the method described in the Examples.

[0035] [6] In the adhesive composition for an electrochemical device functional layer according to any one of [1] to [5] above, the viscosity is preferably 0.5 mPa·s or more and 10 mPa·s or less.

[0036] When the viscosity of the adhesive composition for an electrochemical device functional layer is within the above range, coating stability can be improved.

[0037] In this specification, the viscosity of the adhesive composition for an electrochemical device functional layer can be measured by the method described in Examples.

[0038] [7] The binder composition for an electrochemical device functional layer according to any one of [1] to [6] above preferably further contains a granular binder material.

[0039] If the adhesive composition for an electrochemical device functional layer further contains a particulate adhesive material, the adhesiveness of the functional layer can be improved.

[0040] [8] In the adhesive composition for an electrochemical device functional layer according to any one of [1] to [7] above, the solid content concentration is preferably 10.0 mass % or more and 35.0 mass % or less.

[0041] When the solid content concentration of the adhesive composition for an electrochemical device functional layer is equal to or greater than the above lower limit, the number of coating operations when forming the functional layer can be reduced, thereby improving the productivity of the functional layer.

[0042] On the other hand, if the solid content concentration of the binder composition for electrochemical device functional layer is below the above upper limit, the long-term redispersibility of the binder composition for electrochemical device functional layer can be improved. In addition, the redispersibility after short-term storage (hereinafter sometimes referred to as "short-term redispersibility") can be improved. In this specification, "short-term" generally refers to less than 5 days.

[0043] [9] The adhesive composition for an electrochemical device functional layer according to any one of [1] to [8] above preferably further contains an amine compound.

[0044] If the adhesive composition for an electrochemical device functional layer further contains an amine compound, corruption of the adhesive composition for an electrochemical device functional layer can be suppressed, thereby improving the storage stability of the adhesive composition for an electrochemical device functional layer.

[0045] In addition, the present invention aims to advantageously solve the above-mentioned problems.

[10] The present invention is a slurry composition for an electrochemical element functional layer, which comprises the binder composition for an electrochemical element functional layer according to any one of the above-mentioned [1] to [9] and non-conductive heat-resistant particles.

[0046] According to the above-described slurry composition for an electrochemical element functional layer, the functional layer can exhibit excellent adhesiveness.

[0047] In addition, the present invention aims to advantageously solve the above-mentioned problems.

[11] The present invention is a laminate for an electrochemical element, which has a substrate and a functional layer formed on the substrate, and the functional layer is formed using the adhesive composition for the electrochemical element functional layer of any one of the above-mentioned [1] to [9], or the slurry composition for the electrochemical element functional layer of the above-mentioned

[10] .

[0048] The electrochemical device laminate as described above can improve the electrochemical characteristics (for example, cycle characteristics, output characteristics, etc.) of an electrochemical device having the electrochemical device laminate.

[0049] Furthermore, the present invention aims to advantageously solve the above-mentioned problems.

[12] The present invention is an electrochemical element comprising the electrochemical element laminate according to

[11] .

[0050] The electrochemical device described above can exhibit excellent electrochemical characteristics (for example, cycle characteristics, output characteristics, etc.).

[0051] Effects of the Invention

[0052] According to the present invention, it is possible to provide a binder composition for a functional layer of an electrochemical device that has excellent redispersibility after long-term storage and can enable the functional layer to exhibit excellent adhesiveness.

[0053] Furthermore, according to the present invention, there can be provided a slurry composition for an electrochemical element functional layer using the binder composition for an electrochemical element functional layer of the present invention.

[0054] Furthermore, according to the present invention, there can be provided a laminate for an electrochemical device having a functional layer formed using the binder composition for an electrochemical device functional layer or the slurry composition for an electrochemical device functional layer.

[0055] Furthermore, according to the present invention, an electrochemical device including the above-mentioned electrochemical device laminate can be provided. DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present invention will be described in detail.

[0057] Here, the binder composition for the electrochemical element functional layer of the present invention (hereinafter sometimes referred to as the "binder composition") can be used to prepare the slurry composition for the electrochemical element functional layer of the present invention (hereinafter sometimes referred to as the "slurry composition"). In addition, the binder composition of the present invention and the slurry composition of the present invention can be used as a material for forming the functional layer of the electrochemical element laminate of the present invention (hereinafter sometimes referred to as the "laminate"). In addition, the electrochemical element laminate of the present invention can be used to manufacture the electrochemical element of the present invention.

[0058] (Adhesive composition for electrochemical device functional layer)

[0059] The binder composition for the electrochemical element functional layer of the present invention comprises a granular polymer having a specified volume particle size D50 and a specified true specific gravity, a water-soluble polymer, and water, and may optionally further comprise a granular binder, an amine compound, and other ingredients. Such a binder composition exhibits excellent long-term redispersibility and enables the functional layer to exhibit excellent adhesion. It is speculated that this is because, by providing the granular polymer with a specified volume particle size D50, the contact area between the functional layer formed using the binder composition and the battery component is well ensured, and if the granular polymer having a specified volume particle size D50 and a specified true specific gravity coexists with the water-soluble polymer in the binder composition, when the granular polymer precipitates, the water-soluble polymer appropriately enters the gaps between the granular polymer, effectively suppressing the aggregation of the granular polymer caused by long-term storage.

[0060] Furthermore, the adhesive composition of the present invention generally does not contain the non-conductive heat-resistant particles described below.

[0061] <Granular Polymer>

[0062] Particulate polymers function as adhesive particles in the functional layer, bonding battery components together. Particulate polymers are particles in the binder composition, with a volume particle size (D50) of 1.0 μm to 15.0 μm and a true specific gravity of 1.00 to 2.00. Using such particulate polymers improves the long-term redispersibility of the binder composition and the adhesiveness of the functional layer.

[0063] Furthermore, the particulate polymer can be in a granular form or any other shape after the battery components are bonded together via a functional layer formed using an adhesive composition, etc. Furthermore, the particulate polymer can be a crystalline polymer, an amorphous polymer, or a mixture thereof.

[0064] <<Properties of Granular Polymer>>

[0065] The volume particle size D50 of the granular polymer needs to be 1.0 μm or more, preferably 1.5 μm or more, more preferably 1.8 μm or more, and further preferably 2.0 μm or more, and needs to be 15.0 μm or less, preferably 13.0 μm or less, more preferably 10.0 μm or less, and further preferably 8.0 μm or less.

[0066] When the volume particle size D50 of the particulate polymer is equal to or greater than the above lower limit, the adhesiveness of the functional layer can be improved.

[0067] On the other hand, if the volume particle size D50 of the particulate polymer is equal to or less than the upper limit, the particulate polymer can be effectively suppressed from falling out of the functional layer, and the redispersibility of the adhesive composition can be improved.

[0068] The volume particle size D50 of the granular polymer can be adjusted by the type and amount of the metal hydroxide used in preparing the granular polymer, and the method and conditions for preparing the granular polymer.

[0069] The true specific gravity of the granular polymer needs to be 1.00 or more, preferably 1.02 or more, more preferably 1.04 or more, and further preferably 1.05 or more, and needs to be 2.00 or less, preferably 1.50 or less, more preferably 1.30 or less, and further preferably 1.20 or less.

[0070] When the true specific gravity of the particulate polymer is within the above range, the particulate polymer can be well dispersed in the adhesive composition immediately after the adhesive composition is prepared.

[0071] The true specific gravity of the granular polymer can be adjusted by the composition of the particles contained in the granular polymer, the type and amount of the metal hydroxide used in preparing the granular polymer, and the preparation method and conditions of the granular polymer.

[0072] Here, the particulate polymer is not particularly limited and may be solid particles having a dense interior, porous particles having a porous interior, or hollow particles having a hollow interior. Solid particles are preferred from the viewpoint of improving the adhesion of the functional layer.

[0073] In addition, the internal structure of the particulate polymer can be adjusted by the preparation method and preparation conditions of the particulate polymer.

[0074] The average circularity of the particulate polymer is preferably 0.900 or more, more preferably 0.920 or more, and even more preferably 0.950 or more, and is preferably 0.999 or less, more preferably 0.995 or less, and even more preferably 0.990 or less.

[0075] When the average circularity of the particulate polymer is within the above range, the adhesiveness of the functional layer can be improved.

[0076] The median circularity of the particulate polymer is preferably 0.900 or greater, more preferably 0.950 or greater, further preferably 0.980 or greater, and is preferably 0.999 or less, more preferably 0.998 or less.

[0077] When the average circularity and the median circularity of the particulate polymer are within the above ranges, the adhesiveness of the functional layer can be improved.

[0078] In this specification, the average circularity and median circularity of the particulate polymer can be measured by the method described in Examples.

[0079] In addition, the average circularity and median circularity of the particulate polymer can be adjusted by the preparation method and preparation conditions of the particulate polymer.

[0080] The glass transition temperature (Tg) of the particulate polymer is preferably 0°C or higher, more preferably 25°C or higher, further preferably 40°C or higher, further preferably 50°C or higher, and preferably 200°C or lower, more preferably 150°C or lower, further preferably 120°C or lower, further preferably 100°C or lower.

[0081] When the glass transition temperature of the particulate polymer is not less than the above lower limit, the anti-blocking property of the functional layer can be improved.

[0082] On the other hand, when the glass transition temperature of the particulate polymer is not more than the above upper limit, the adhesiveness of the functional layer, particularly the adhesiveness to the electrode, can be improved.

[0083] <<Polymer Composition Contained in Particles Constituting Granular Polymer>>

[0084] The polymer contained in the particles constituting the granular polymer (hereinafter sometimes referred to as "polymer A") is not particularly limited as long as at least the volume particle size D50 and true specific gravity of the granular polymer are within the above ranges, and known polymers can be used.

[0085] Furthermore, the particulate polymer may optionally further contain a wax described below in addition to the polymer A.

[0086] Here, examples of the monomer units contained in the polymer A include aromatic monovinyl monomer units, crosslinkable monomer units, and (meth)acrylic acid alkyl ester monomer units.

[0087] Furthermore, a polyester polymer containing a low molecular weight polyol monomer unit and a polycarboxylic acid monomer unit can also be used as polymer A. Such a polyester polymer can be polymerized by, for example, dehydration condensation of a low molecular weight polyol monomer and a polycarboxylic acid monomer.

[0088] In this specification, the polymer "contains monomer units" means "a polymer obtained by using the monomer contains a structural unit derived from the monomer." In addition, the content ratio of the monomer units in the polymer can be expressed as 1 It can be measured by nuclear magnetic resonance (NMR) methods such as H-NMR.

[0089] In addition, in this specification, "(meth)acrylic acid" means acrylic acid and / or methacrylic acid.

[0090] -Aromatic monovinyl monomer unit-

[0091] Examples of the aromatic monovinyl monomer capable of forming the aromatic monovinyl monomer unit are not particularly limited, and examples thereof include styrene, α-methylstyrene, butoxystyrene, and vinylnaphthalene. Among them, styrene is preferred.

[0092] These aromatic monovinyl monomers may be used alone or in combination of two or more at any ratio.

[0093] When all repeating units in polymer A are 100% by mass, the content ratio of the aromatic monovinyl monomer unit in polymer A is preferably 30% by mass or more, more preferably 60% by mass or more, preferably 85% by mass or less, more preferably 80% by mass or less, and further preferably 75% by mass or less.

[0094] When the content of the aromatic monovinyl monomer units is not less than the above lower limit, the elasticity of the particulate polymer is improved, the strength of the obtained functional layer is ensured, and the adhesion between the functional layer and the substrate can be improved.

[0095] On the other hand, if the content of the aromatic monovinyl monomer units is below the upper limit, the flexibility of the particulate polymer is improved, and the film-forming properties of the adhesive composition during drying are improved, thereby improving the adhesion between the functional layer and the substrate.

[0096] - Cross-linking monomer unit -

[0097] 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 such a multifunctional monomer, for example, allyl (meth)acrylate monomers such as allyl methacrylate; aromatic divinyl monomers such as divinylbenzene and divinylnaphthalene; di(meth)acrylate monomers such as diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butanediol diacrylate; tri(meth)acrylate monomers such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; ethylenically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate. Here, as an aromatic divinyl monomer, divinylbenzene is preferred, as a di(meth)acrylate monomer, ethylene glycol dimethacrylate is preferred, as a tri(meth)acrylate monomer, trimethylolpropane trimethacrylate is preferred, and as an ethylenically unsaturated monomer containing epoxy groups, glycidyl methacrylate is preferred.

[0098] These crosslinking monomers may be used alone or in combination of two or more at any ratio.

[0099] Here, the crosslinkable monomer unit is preferably at least one crosslinkable monomer unit selected from the group consisting of an aromatic divinyl monomer unit, a di(meth)acrylate monomer unit, a tri(meth)acrylate monomer unit, and an ethylenically unsaturated monomer unit containing an epoxy group. Specifically, the granular polymer is preferably formed from particles comprising a polymer A containing at least one crosslinkable monomer unit selected from the group consisting of an aromatic divinyl monomer unit, a di(meth)acrylate monomer unit, a tri(meth)acrylate monomer unit, and an ethylenically unsaturated monomer unit containing an epoxy group. More preferably, the granular polymer is formed from particles comprising a polymer A containing at least one crosslinkable monomer unit selected from the group consisting of a di(meth)acrylate monomer unit and an ethylenically unsaturated monomer unit containing an epoxy group. Further preferably, the granular polymer is formed from particles comprising a polymer A containing both a di(meth)acrylate monomer unit and an ethylenically unsaturated monomer unit containing an epoxy group.

[0100] If the particulate polymer is formed from particles containing polymer A containing the aforementioned crosslinkable monomer units, the adhesion of the functional layer can be improved. Furthermore, if the particulate polymer is formed from particles containing polymer A containing the aforementioned crosslinkable monomer units, excessive deformation of the particulate polymer can be suppressed, resulting in improved anti-blocking properties of the functional layer. Furthermore, in an electrochemical device, the amount of components of the particulate polymer that may increase resistance and dissolve in the electrolyte is reduced, resulting in improved cycling characteristics of the electrochemical device.

[0101] When the amount of all repeating units in polymer A is 100% by mass, the content ratio of the crosslinkable monomer unit in polymer A is preferably 0.1% by mass or more, more preferably 5% by mass or more, preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 12% by mass or less.

[0102] When the content of the cross-linkable monomer unit is not less than the above lower limit, the anti-blocking property of the functional layer and the cycle characteristics of the electrochemical device can be improved.

[0103] On the other hand, when the content of the crosslinkable monomer unit is below the upper limit, the particulate polymer is appropriately deformed at the contact surface of the battery member with the functional layer formed using the adhesive composition, thereby improving the adhesiveness of the functional layer.

[0104] -(Meth)acrylate monomer unit-

[0105] Examples of the alkyl (meth)acrylate monomers that can form the alkyl (meth)acrylate monomer units include butyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and t-butyl acrylate; octyl acrylates such as pentyl acrylate, hexyl acrylate, heptyl acrylate, and 2-ethylhexyl acrylate; nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, and stearic acid acrylate; and butyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and t-butyl methacrylate; octyl methacrylates such as pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, and 2-ethylhexyl methacrylate; nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearic acid acrylate. Among them, n-butyl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate are particularly preferred.

[0106] These alkyl (meth)acrylate monomers may be used alone or in combination of two or more at any ratio.

[0107] When all repeating units in polymer A are 100% by mass, the content ratio of the (meth)acrylate monomer unit in polymer A is preferably 10% by mass or more, more preferably 15% by mass or more, preferably 90% by mass or less, more preferably 40% by mass or less, and even more preferably 20% by mass or less.

[0108] When the content of the alkyl (meth)acrylate monomer units is not less than the above lower limit, an excessive decrease in the glass transition temperature of the particulate polymer can be avoided, and the anti-blocking property of the obtained functional layer can be improved.

[0109] On the other hand, when the content ratio of the alkyl (meth)acrylate monomer unit is not more than the above upper limit, the adhesion between the functional layer and the substrate can be improved.

[0110] -Low molecular weight polyol monomer unit-

[0111] Examples of low molecular weight polyol units that can form low molecular weight polyol monomer units include aliphatic polyols such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, 1,4-cyclohexanedimethanol, and glycerol; and aromatic diols such as 1,4-dihydroxymethylbenzene, bisphenol A, ethylene oxide adducts of bisphenol A, and propylene oxide adducts of bisphenol A. Among these, aromatic diols are preferred, and ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A are more preferred. Among these, ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A are preferred.

[0112] In addition, these low molecular weight polyol monomers can be used alone or in combination of two or more at any ratio, preferably in combination of two or more. In particular, as the low molecular weight polyol monomer, it is preferred to use an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A in combination.

[0113] Here, the molecular weight of the low molecular weight polyol monomer is usually 1000 or less, preferably 500 or less.

[0114] When all repeating units in polymer A are 100% by mass, the content ratio of the low molecular weight polyol monomer units in polymer A (the total when containing two or more types) is preferably 50% by mass or more, more preferably 60% by mass or more, preferably 90% by mass or less, more preferably 80% by mass or less.

[0115] - Polycarboxylic acid monomer unit -

[0116] As the polycarboxylic acid monomer capable of forming the polycarboxylic acid monomer unit, polycarboxylic acids and polycarboxylic acid anhydrides can be used. Examples of the polycarboxylic acid monomer include: aliphatic polycarboxylic acids such as malonic acid, ethylmalonic acid, dimethylmalonic acid, succinic acid, 2,2-dimethylsuccinic acid, succinic anhydride, alkenylsuccinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, dimer acid, and trimer acid; 1,1-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, tetrahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, Alicyclic polycarboxylic acids such as cyclohexane-1,2,4-tricarboxylic acid-1,2-anhydride, nadic anhydride, and chlorophthalic anhydride; aromatic polycarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, phthalic anhydride, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic anhydride, naphthalenedicarboxylic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, biphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-p,p'-dicarboxylic acid, benzophenonetetracarboxylic acid, benzophenonetetracarboxylic dianhydride, 5-sodium sulfoisophthalic acid, tetrachlorophthalic anhydride, and tetrabromophthalic anhydride. Among these, fumaric acid and trimellitic anhydride are preferred.

[0117] These polycarboxylic acid monomers may be used alone or in combination of two or more at any ratio, preferably in combination of two or more. In particular, fumaric acid and trimellitic anhydride are preferably used in combination as the polycarboxylic acid monomer.

[0118] When all repeating units in polymer A are 100% by mass, the content ratio of the polycarboxylic acid monomer units in polymer A (the total when containing two or more types) is preferably 10% by mass or more, more preferably 20% by mass or more, preferably 50% by mass or less, more preferably 40% by mass or less.

[0119] -Other monomer units A-

[0120] Here, the polymer A may contain monomer units other than the above-mentioned monomer units (hereinafter sometimes referred to as "other monomer units A"). Here, examples of the other monomer units A include nitrile group-containing monomer units.

[0121] 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-alkyl acrylonitriles such as methacrylonitrile and α-ethylacrylonitrile.

[0122] These nitrile group-containing monomers may be used alone or in combination of two or more at any ratio.

[0123] When all repeating units in the polymer A are 100% by mass, the content of other monomer units A in the polymer A is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less.

[0124] - Preferred Embodiments of Polymer A -

[0125] Here, polymer A preferably contains at least one monomer unit selected from an aromatic monovinyl monomer unit, a crosslinking monomer unit, and an alkyl (meth)acrylate monomer unit, and preferably contains an aromatic monovinyl monomer unit and a crosslinking monomer unit, or contains an alkyl (meth)acrylate monomer unit and a crosslinking monomer unit.

[0126] If polymer A contains the aforementioned monomer units, the adhesiveness of the functional layer can be improved. In addition, the amount of particulate polymer components that may cause an increase in resistance in the electrochemical device can be reduced, thereby improving the cycling characteristics of the electrochemical device. Furthermore, the long-term redispersibility of the binder composition can be enhanced.

[0127] <<Content Ratio of Polymer A in Granular Polymer>>

[0128] The content of the polymer A in the particulate polymer is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0129] <<Method for producing particles comprising polymer A>>

[0130] The particles containing polymer A can be prepared by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water. Here, the ratio of each monomer in the monomer composition is generally the same as the ratio of each monomer unit in polymer A.

[0131] The polymerization method is not particularly limited, and any of methods such as suspension polymerization, emulsion polymerization, emulsion polymerization coacervation, pulverization, dissolution suspension, and seed polymerization can be used. From the viewpoints of being able to produce granular polymers at low cost and easily adjusting the circularity of the obtained granular polymers, suspension polymerization is particularly preferred. In addition, any of free radical polymerization, living radical polymerization, and the like can also be used as the polymerization reaction.

[0132] The monomer composition used to prepare the pellets containing the 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.

[0133] Here, a method for producing particles containing polymer A by suspension polymerization will be described as an example, but the method for producing particles containing polymer A is not limited thereto.

[0134] - Preparation of particles comprising polymer A by suspension polymerization -

[0135] (1) Preparation of monomer composition

[0136] First, monomers constituting the desired polymer A and other compounding agents added as needed are mixed to prepare a monomer composition.

[0137] (2) Droplet formation

[0138] Next, the monomer composition is dispersed in water, and a polymerization initiator is added to form droplets of the monomer composition. The droplets can be formed by, for example, shearing and stirring the water containing the monomer composition using a disperser such as an emulsifier.

[0139] When a disperser is used to form droplets, the rotation speed of the disperser is preferably greater than 8000 rpm, more preferably 9500 rpm or greater, further preferably 11000 rpm or greater, and preferably less than 15000 rpm, more preferably 14000 rpm or less, further preferably 13000 rpm or less.

[0140] Examples of the polymerization initiator include oil-soluble polymerization initiators such as t-butyl peroxy-2-ethylhexanoate and azobisisobutyronitrile. The polymerization initiator may be added after the monomer composition is dispersed in water and before droplets are formed, or may be added to the monomer composition before it is dispersed in water.

[0141] From the perspective of stabilizing the formed droplets of the monomer composition in water, it is preferred to add a dispersion stabilizer to the water to form the droplets of the monomer composition. Examples of the dispersion stabilizer include metal hydroxides such as magnesium hydroxide and sodium dodecylbenzenesulfonate. The dispersion stabilizer can be added, for example, in the form of a colloidal dispersion of the dispersion stabilizer dispersed in water.

[0142] (3) Aggregation

[0143] Next, after droplets of the monomer composition are formed, the water containing the formed droplets is heated to initiate polymerization, thereby forming particles containing polymer A in the water. In this case, the polymerization reaction temperature is preferably 50° C. or higher and 95° C. or lower. Furthermore, the polymerization reaction time is preferably 1 hour or longer, preferably 10 hours or shorter, more preferably 8 hours or shorter, and even more preferably 6 hours or shorter.

[0144] (4) Cleaning, filtering, dehydration and drying processes

[0145] After the polymerization is completed, the water containing the particles containing the polymer A is washed, filtered, and dried according to a conventional method, thereby obtaining particles containing the polymer A.

[0146] Wax

[0147] Wax is a component that can be included in the particulate polymer along with polymer A. If the particulate polymer contains wax, for example, in an electrochemical device having a separator with a functional layer formed using the binder composition, polymer A can be rapidly melted when the electrochemical device is abnormally heated, such as by an electrode short circuit, thereby appropriately shutting down the electrochemical device. In other words, a shutdown function can be imparted to the separator with a functional layer.

[0148] The melting point of the wax is usually lower than 95°C, preferably 90°C or lower, more preferably 81°C or lower, further preferably 70°C or lower, further preferably 60°C or lower, preferably 40°C or higher, more preferably 44°C or higher.

[0149] When the melting point of the wax is lower than the upper limit, the obtained functional layer can enable the separator to exhibit an excellent shutdown function.

[0150] On the other hand, when the melting point of the wax is not less than the above lower limit, the particle stability of the particulate polymer in the adhesive composition can be improved, and the occurrence of blocking can be effectively suppressed even when the battery member having the functional layer is wound and overlapped.

[0151] The wax contained in the particulate polymer is not particularly limited as long as the melting point is lower than the upper limit, and plant waxes, animal waxes, petroleum waxes, synthetic waxes, and modified products thereof can be used.

[0152] Specific examples of the plant wax include candelilla wax, carnauba wax, rice wax, wood wax, and jojoba oil.

[0153] Specific examples of animal wax include beeswax and the like.

[0154] Specific examples of the petroleum wax include paraffin wax, microcrystalline wax, and petrolatum wax.

[0155] Synthetic waxes can be classified into Fischer-Tropsch waxes, polyolefin waxes, ester waxes, and the like.

[0156] Specific examples of the polyolefin wax include polyethylene wax, polypropylene wax, and polybutene wax.

[0157] As the ester wax, either monohydric alcohol fatty acid esters or polyhydric alcohol fatty acid esters can be used. Specific examples of monohydric alcohol fatty acid esters include behenyl stearate. Specific examples of polyhydric alcohol fatty acid esters include pentaerythritol esters such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, pentaerythritol tetrastearate, pentaerythritol tetralaurate, and pentaerythritol tetrabehenate; and dipentaerythritol esters such as dipentaerythritol hexamyristate, dipentaerythritol hexapalmitate, and dipentaerythritol hexalaurate.

[0158] These waxes may be used alone or in combination of two or more.

[0159] The content of the wax in the granular polymer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 5 parts by mass or more, further preferably 6 parts by mass or more, and is preferably 30 parts by mass or less, more preferably 23 parts by mass or less, further preferably 15 parts by mass or less, further preferably 12 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of polymer A.

[0160] When the content of the wax in the particulate polymer is not less than the above lower limit, the obtained functional layer can enable the separator to exhibit a more excellent shutdown function.

[0161] On the other hand, when the wax content in the particulate polymer is below the upper limit, the particle stability of the particulate polymer in the adhesive composition can be improved, and the occurrence of blocking can be well suppressed even when the battery member having the functional layer is wound and overlapped.

[0162] <Water-soluble polymer>

[0163] The water-soluble polymer is a component that enables the above-mentioned particulate polymer and other ingredients to be well dispersed and redispersed in water. In addition, if a water-soluble polymer is used together with the specified particulate polymer, the long-term redispersibility of the adhesive composition and the adhesiveness of the functional layer can be improved.

[0164] From the perspective of improving the long-term redispersibility of the binder composition, the water-soluble polymer preferably has an acid group. Examples of the acid group include carboxylic acid groups, sulfonic acid groups, and phosphoric acid groups. The water-soluble polymer may have only one of these acid groups, or may have two or more. Among these, carboxylic acid groups and sulfonic acid groups are preferred, and carboxylic acid groups are more preferred.

[0165] When the water-soluble polymer has an acid group, the water-soluble polymer may be in the form of a salt (a salt of the water-soluble polymer). That is, in the present invention, "water-soluble polymer" also includes salts of the water-soluble polymer. Examples of such salts include alkali metal salts such as lithium salts and sodium salts, and ammonium salts.

[0166] In addition, from the viewpoint of improving the long-term redispersibility of the adhesive composition, the water-soluble polymer is preferably in the form of a salt (a salt of a water-soluble polymer). In addition, if the water-soluble polymer is in the form of a salt, the long-term aggregation inhibition of the adhesive composition can be improved.

[0167] Here, the method for introducing acid groups into the water-soluble polymer is not particularly limited. The polymer can be prepared by addition polymerization of a monomer composition containing at least a monomer containing the above-mentioned acid group (acid group-containing monomer) to obtain a water-soluble polymer containing acid group-containing monomer units. The water-soluble polymer having the above-mentioned acid group can also be obtained by modifying any polymer (for example, terminal modification). The former is preferred.

[0168] Examples of the former water-soluble polymer include polyacrylic acid, and examples of the latter water-soluble polymer include carboxymethyl cellulose.

[0169] <<Acid group-containing monomer unit>>

[0170] Examples of the acid group-containing monomer capable of forming the acid group-containing monomer unit include monomers having a carboxylic acid group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, etc. These monomers may be used alone or in combination of two or more.

[0171] Examples of the monomer having a carboxylic acid group include monocarboxylic acids and derivatives thereof, dicarboxylic acids and anhydrides thereof, and derivatives thereof.

[0172] Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, and crotonic acid.

[0173] Examples of the monocarboxylic acid derivative include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, and β-diaminoacrylic acid.

[0174] Examples of the dicarboxylic acid include maleic acid, fumaric acid, and itaconic acid.

[0175] Examples of the dicarboxylic acid derivatives include maleic acid esters such as methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, methylallyl maleate, diphenyl maleate, nonyl maleate, decyl maleate, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleate.

[0176] Examples of the anhydride of dicarboxylic acid include maleic anhydride, acrylic anhydride, methylmaleic anhydride, and dimethylmaleic anhydride.

[0177] Furthermore, as the monomer having a carboxylic acid group, an acid anhydride that generates a carboxylic acid group by hydrolysis can also be used.

[0178] Other examples include monoesters and diesters of α,β-ethylenically unsaturated polycarboxylic acids such as monoethyl maleate, diethyl maleate, monobutyl maleate, dibutyl maleate, monoethyl fumarate, diethyl fumarate, monobutyl fumarate, dibutyl fumarate, monocyclohexyl fumarate, dicyclohexyl fumarate, monoethyl itaconate, diethyl itaconate, monobutyl itaconate, and dibutyl itaconate.

[0179] Examples of the monomer having a sulfonic acid group include vinylsulfonic acid, methylvinylsulfonic acid, (meth)allylsulfonic acid, styrenesulfonic acid, 2-sulfonic ethyl (meth)acrylate, 2-acrylamide-2-methylpropanesulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid.

[0180] In addition, in this specification, "(meth)allyl group" means an allyl group and / or a methallyl group.

[0181] Examples of the monomer having a phosphoric acid group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, ethyl-(meth)acryloyloxyethyl phosphate, vinylphosphonic acid, and dimethyl vinylphosphonate.

[0182] In addition, in this specification, "(meth)acryloyl" means acryloyl and / or methacryloyl.

[0183] When the amount of all repeating units in the water-soluble polymer is 100% by mass, the content ratio of the acid group-containing monomer units in the water-soluble polymer is preferably 20% by mass or more, more preferably 50% by mass or more, further preferably 80% by mass or more, and particularly preferably 100% by mass. In other words, it is particularly preferred that the water-soluble polymer be composed solely of acid group-containing monomer units.

[0184] <<Other monomer units B>>

[0185] The water-soluble polymer may contain monomer units other than the acid group-containing monomer units (hereinafter sometimes referred to as "other monomer units B"). Examples of other monomer units B include the (meth)acrylate alkyl ester monomer units, the crosslinkable monomer units, and hydroxyl group-containing monomer units.

[0186] Here, examples of the hydroxyl-containing monomers forming the hydroxyl-containing monomer units include alkanol esters of ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl acrylate (2-hydroxyethyl acrylate), 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate (4-hydroxybutyl acrylate), 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, di-2-hydroxypropyl itaconate, 1,4-cyclohexanedimethanol monoacrylate, and 2-hydroxy-3-phenoxypropyl acrylate; general formula: CH2=CR 1 -COO-(C q H 2q O) p -H (wherein p represents an integer of 2 to 9, q represents an integer of 2 to 4, R 1Esters of polyalkylene glycol represented by (a) (representing hydrogen or a methyl group) and (meth)acrylic acid; mono(meth)acrylates of dihydroxy esters of dicarboxylic acids such as 2-hydroxyethyl-2'-(meth)acryloyloxyphthalate and 2-hydroxyethyl-2'-(meth)acryloyloxysuccinate; vinyl ethers such as 2-hydroxyethyl vinyl ether and 2-hydroxypropyl vinyl ether; (meth)allyl-2-hydroxyethyl ether, (meth)allyl-2-hydroxypropyl ether, (meth)allyl-3-hydroxypropyl ether, (meth)allyl-2-hydroxybutyl ether, (meth)allyl-3-hydroxybutyl ether, (meth)allyl-4-hydroxybutyl ether, (meth)allyl-6-hydroxyhexyl mono(meth)allyl ethers of alkylene glycols such as propylene glycol, propylene glycol, and propylene glycol; mono(meth)allyl ethers of polyoxyalkylene glycols such as diethylene glycol mono(meth)allyl ether and dipropylene glycol mono(meth)allyl ether; mono(meth)allyl ethers of halogen-substituted and hydroxyl-substituted (poly)alkylene glycols such as glycerol mono(meth)allyl ether, (meth)allyl-2-chloro-3-hydroxypropyl ether and (meth)allyl-2-hydroxy-3-chloropropyl ether; mono(meth)allyl ethers of polyphenols such as eugenol and isoeugenol and their halogen-substituted products; (meth)allyl sulfides of alkylene glycols such as (meth)allyl-2-hydroxyethyl sulfide and (meth)allyl-2-hydroxypropyl sulfide.

[0187] These hydroxyl group-containing monomers may be used alone or in combination of two or more at any ratio.

[0188] <<Weight Average Molecular Weight of Water-Soluble Polymer>>

[0189] The weight average molecular weight (Mw) of the water-soluble polymer is preferably 5,000 or more, more preferably 5,500 or more, further preferably 6,000 or more, further preferably 6,500 or more, and preferably 200,000 or less, more preferably 180,000 or less, further preferably 160,000 or less, further preferably 150,000 or less.

[0190] When the weight average molecular weight of the water-soluble polymer is within the above range, the long-term redispersibility of the adhesive composition can be improved.

[0191] The weight average molecular weight (Mw) of the water-soluble polymer is preferably 5,000 or more, more preferably 5,500 or more, further preferably 6,000 or more, further preferably 6,500 or more, still further preferably 80,000 or more, further preferably 90,000 or more, further preferably 100,000 or more, preferably 500,000 or less, more preferably 300,000 or less, further preferably 200,000 or less, further preferably 180,000 or less, further preferably 160,000 or less, further preferably 150,000 or less, and particularly preferably 120,000 or less.

[0192] When the weight average molecular weight of the water-soluble polymer is within the above range, the long-term redispersibility and long-term aggregation inhibition of the adhesive composition can be improved.

[0193] Furthermore, when the weight average molecular weight of the water-soluble polymer is not more than the above upper limit, the adhesiveness of the functional layer can be improved.

[0194] In order to particularly improve long-term aggregation inhibition, the water-soluble polymer is preferably in the form of a salt and has a weight average molecular weight of 80,000 or more, more preferably 90,000 or more, and even more preferably 100,000 or more.

[0195] <<Content of water-soluble polymer>>

[0196] The content of the water-soluble polymer in the adhesive composition relative to 100 parts by mass of the granular polymer is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, further preferably 0.4 parts by mass or more, further preferably 0.5 parts by mass or more, preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, further preferably 3.5 parts by mass or less, further preferably 3.0 parts by mass or less.

[0197] When the content of the water-soluble polymer in the adhesive composition is not less than the above lower limit, the long-term redispersibility of the adhesive composition can be improved.

[0198] On the other hand, when the content of the water-soluble polymer in the binder composition is not more than the upper limit, an increase in the resistance value of the electrochemical device can be effectively suppressed, thereby improving the cycle characteristics of the electrochemical device.

[0199] <<Method for preparing water-soluble polymer>>

[0200] Water-soluble polymers can be produced by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water. The proportion of each monomer in the monomer composition can be determined based on the proportion of each monomer unit in the water-soluble polymer. Furthermore, during the preparation of the water-soluble polymer, an acid or base may be added to neutralize the solution.

[0201] Furthermore, the polymerization method is not particularly limited, and any method such as solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, and emulsion polymerization coacervation can be used. In addition, as the polymerization reaction, any reaction such as ionic polymerization, free radical polymerization, and living free radical polymerization can also be used. Furthermore, as the polymerization method, any of random polymerization and block polymerization can be used.

[0202] In addition, the emulsifier, dispersant, polymerization initiator, polymerization aid (polymerization accelerator), molecular weight regulator, reaction terminator and other additives used in the polymerization can use commonly used additives. The usage amount of these additives can also be a commonly used amount. The polymerization conditions can be appropriately adjusted according to the type of polymerization method and polymerization initiator, etc.

[0203] <Granular bonding material>

[0204] The particulate binder material optionally included in the adhesive composition of the present invention can function as binder particles for bonding battery components together, similarly to the particulate polymer. If the adhesive composition of the present invention includes the particulate binder material, the adhesiveness of the functional layer can be improved.

[0205] Furthermore, the particulate binder can also function as a binder that binds components such as the particulate polymer contained in the functional layer to each other and prevents them from falling off.

[0206] Furthermore, after the battery components are bonded together via the functional layer formed using the adhesive composition, the granular adhesive material may be in a granular form or in any other arbitrary shape.

[0207] <<Volume particle size D50 of granular bonding material>>

[0208] The volume particle size D50 of the granular binder is preferably 0.08 μm or more, more preferably 0.1 μm or more, further preferably 0.12 μm or more, preferably 1.0 μm or less, more preferably 0.5 μm or less, further preferably 0.45 μm or less, and further preferably 0.4 μm or less.

[0209] If the volume particle size D50 of the granular binder material is greater than the above lower limit, it can effectively suppress the reduction of the air permeability of the functional layer and effectively suppress the reduction of the ion conductivity of the functional layer. As a result, the electrochemical characteristics (particularly the output characteristics) of the electrochemical device can be improved. In addition, the adhesion of the functional layer can be improved.

[0210] On the other hand, when the volume particle size D50 of the particulate binder is equal to or less than the upper limit, a sufficient contact area with the particulate polymer and the like can be ensured, and the particulate polymer and the like can be effectively suppressed from falling off from the functional layer.

[0211] In this specification, the volume particle size D50 of the granular binder refers to the particle size at which the cumulative volume calculated from the smallest particle size in the particle size distribution (volume basis) measured by laser diffraction method accounts for 50%, and can be measured by the method described in Examples.

[0212] <<Composition of polymer contained in particles constituting the granular binder>>

[0213] The polymer (hereinafter also referred to as "polymer B") contained in the particles constituting the granular binder material is not particularly limited, and examples thereof include known water-insoluble polymers that can be dispersed in water, such as binder resins such as thermoplastic elastomers. Preferred thermoplastic elastomers include conjugated diene polymers and acrylic acid polymers (ACL).

[0214] These granular binders may be used alone or in combination of two or more at any ratio.

[0215] The acrylic polymer refers to a polymer containing an alkyl (meth)acrylate monomer unit. In addition to the alkyl (meth)acrylate monomer unit, the acrylic polymer may optionally contain monomer units such as an acid group-containing monomer unit, a crosslinking monomer unit, and a nitrile group-containing monomer unit.

[0216] The conjugated diene polymer refers to a polymer containing conjugated diene monomer units. In addition to the conjugated diene monomer units, the conjugated diene polymer may contain monomer units such as aromatic monovinyl monomer units, acid group-containing monomer units, and hydroxyl group-containing monomer units.

[0217] Specific examples of the conjugated diene polymer include, but are not particularly limited to, styrene-butadiene copolymers (SBR), butadiene rubber (BR), acrylic rubber (NBR) (a copolymer containing acrylonitrile units and butadiene units), and hydrogenated products thereof.

[0218] -(Meth)acrylic acid alkyl ester monomer unit-

[0219] As the alkyl (meth)acrylate monomer that can form the alkyl (meth)acrylate monomer unit that can be contained in the polymer B, the same monomers as those exemplified for the polymer A can be used.

[0220] Here, as the (meth)acrylate monomer that can be used for the polymer B, n-butyl acrylate is preferred.

[0221] When all repeating units in polymer B are 100% by mass, the content ratio of the (meth)acrylate monomer unit in polymer B is preferably 60% by mass or more, more preferably 80% by mass or more, and preferably 98% by mass or less, more preferably 95% by mass or less.

[0222] -Acid group-containing monomer units-

[0223] As the acid group-containing monomer capable of forming the acid group-containing monomer unit that can be contained in the polymer B, the same monomers as those exemplified for the water-soluble polymer can be used.

[0224] Here, as the acid group-containing monomer that can be used for the polymer B, a monomer having a carboxylic acid group is preferable. Among the monomers having a carboxylic acid group, methacrylic acid and itaconic acid are preferable.

[0225] When all repeating units in polymer B are 100 mass %, the content ratio of the acid group-containing monomer unit in polymer B is preferably 0.5 mass % or more, more preferably 2 mass % or more, and preferably 10 mass % or less, more preferably 3.5 mass % or less.

[0226] - Cross-linking monomer unit -

[0227] As the cross-linking monomer capable of forming the cross-linking monomer unit that can be contained in the polymer B, the same monomers as those exemplified for the polymer A can be used.

[0228] Here, allyl (meth)acrylate monomers and epoxy group-containing ethylenically unsaturated monomers are preferred as crosslinking monomers that can be used for polymer B. Allyl (meth)acrylate monomers are preferred, and allyl methacrylate is preferred as epoxy group-containing ethylenically unsaturated monomers.

[0229] The crosslinking monomer may be used alone or in combination of two or more at any ratio, preferably in combination of two or more. In particular, allyl methacrylate and allyl glycidyl ether are preferably used in combination as the crosslinking monomer that can be used for polymer B.

[0230] When all repeating units in polymer B are 100% by mass, the content ratio of the cross-linkable monomer unit in polymer B (the total when containing two or more types) is preferably 1% by mass or more, more preferably 2% by mass or more, and preferably 10% by mass or less, more preferably 4% by mass or less.

[0231] -Nitrile-containing monomer units-

[0232] As the nitrile group-containing monomer that can form the nitrile group-containing monomer unit that can be contained in the polymer B, the same monomers as those exemplified for the polymer A can be used.

[0233] Here, as the nitrile group-containing monomer that can be used for the polymer B, acrylonitrile is preferred.

[0234] When all repeating units in polymer B are 100 mass %, the content ratio of the nitrile group-containing monomer unit in polymer B is preferably 0.5 mass % or more, more preferably 1 mass % or more, and preferably 7 mass % or less, more preferably 3 mass % or less.

[0235] -Conjugated diene monomer unit-

[0236] Examples of the conjugated diene monomer that can form the conjugated diene monomer unit that can be contained in the polymer B include aliphatic conjugated diene monomers such as 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. 1,3-Butadiene is particularly preferred as the conjugated diene monomer.

[0237] These conjugated diene monomers may be used alone or in combination of two or more at any ratio.

[0238] When all repeating units in polymer B are 100% by mass, the content of conjugated diene monomer units in polymer B is preferably 15% by mass or more, more preferably 30% by mass or more, and preferably 60% by mass or less, more preferably 40% by mass or less.

[0239] -Aromatic monovinyl monomer unit-

[0240] As the aromatic monovinyl monomer that can form the aromatic monovinyl monomer unit that can be contained in the polymer B, the same monomers as those exemplified for the polymer A can be used.

[0241] Here, as the aromatic monovinyl monomer that can be used for the polymer B, styrene is preferred.

[0242] When all repeating units in polymer B are 100% by mass, the content ratio of the aromatic monovinyl monomer unit in polymer B is preferably 40% by mass or more, more preferably 60% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less.

[0243] -Hydroxy-containing monomer units-

[0244] As the hydroxyl group-containing monomer capable of forming the hydroxyl group-containing monomer unit that can be contained in the polymer B, the same monomers as those exemplified for the water-soluble polymer can be used.

[0245] Here, as the hydroxyl group-containing monomer that can be used for the polymer B, alkanol esters of ethylenically unsaturated carboxylic acids are preferred, and 2-hydroxyethyl acrylate (2-hydroxyethyl acrylate) is more preferred.

[0246] When all repeating units in polymer B are 100 mass %, the content of the hydroxyl group-containing monomer units in polymer B is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, and preferably 5 mass % or less, more preferably 2 mass % or less.

[0247] <<Method for producing particles comprising polymer B>>

[0248] The particles containing polymer B can be prepared without particular limitation by, for example, polymerizing a monomer composition containing the above monomers in an aqueous solvent such as water.

[0249] The polymerization method and polymerization reaction are not particularly limited, and for example, the polymerization method and polymerization reaction exemplified in the polymerization method of the above-mentioned particulate polymer can be used.

[0250] <<Content of granular binder>>

[0251] The content of the granular adhesive material in the adhesive composition is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 4 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, relative to 100 parts by mass of the granular polymer.

[0252] When the content of the particulate binder in the binder composition is not less than the above lower limit, the long-term redispersibility of the binder composition can be improved.

[0253] On the other hand, when the content of the particulate binder material in the binder composition is not more than the above upper limit, an increase in the resistance value of the electrochemical device can be effectively suppressed, thereby improving the cycle characteristics of the electrochemical device.

[0254] <Amine Compound>

[0255] The adhesive composition of the present invention preferably further comprises an amine compound. If the adhesive composition further comprises an amine compound, corruption of the adhesive composition can be suppressed, thereby improving the storage stability of the adhesive composition.

[0256] Here, the amine compound is not particularly limited, and examples thereof include hydroxylamine sulfate, diethylhydroxylamine, dimethylhydroxylamine, dipropylhydroxylamine, isopropylhydroxylamine, and isothiazolin-based compounds. From the perspective of further improving the storage stability of the adhesive composition, isothiazolin-based compounds are particularly preferred. In addition, examples of isothiazolin-based compounds include 1,2-benzo-4-isothiazoline-3-one and 2-methyl-4-isothiazoline-3-one.

[0257] These amine compounds may be used alone or in combination of two or more at any ratio.

[0258] The content of the amine compound is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, and is preferably 2 parts by mass or less, more preferably 1 part by mass or less, based on 100 parts by mass of the particulate polymer.

[0259] <Other ingredients>

[0260] The adhesive composition of the present invention may optionally contain any other components, without particular limitation, as long as they do not affect the electrochemical reaction in the electrochemical element, and examples thereof include known additives such as dispersants, viscosity modifiers, and wetting agents, and solvents other than water. These other components may be used alone or in combination of two or more.

[0261] Here, as solvents other than water, for example, cyclic aliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ketones such as methyl ethyl ketone and cyclohexanone; esters such as ethyl acetate, butyl acetate, γ-butyrolactone, and ε-caprolactone; nitriles such as acetonitrile and propionitrile; ethers such as tetrahydrofuran; and organic solvents such as alcohols such as methanol, ethanol, and isopropanol.

[0262] The content of other components in the adhesive composition is preferably 1.0 part by mass or less, more preferably 0.5 part by mass or less, further preferably 0.1 part by mass or less, and particularly preferably 0 part by mass per 100 parts by mass of the particulate polymer. That is, it is particularly preferred that the adhesive composition does not contain other components.

[0263] <Properties of the Adhesive Composition for Electrochemical Device Functional Layer>

[0264] The pH of the adhesive composition is preferably 5.5 or higher, more preferably 6.0 or higher, and even more preferably 6.5 or higher, and is preferably 12.0 or lower, more preferably 10.0 or lower, and even more preferably 8.8 or lower.

[0265] When the pH of the adhesive composition is within the above range, aggregation of solid components such as particulate polymers contained in the adhesive composition can be suppressed, thereby improving coating stability.

[0266] The viscosity of the adhesive composition is preferably 0.5 mPa·s or more, more preferably 1.5 mPa·s or more, and preferably 10 mPa·s or less, more preferably 8 mPa·s or less, and even more preferably 5 mPa·s or less.

[0267] When the viscosity of the adhesive composition is within the above range, coating stability can be improved.

[0268] <Solid Content Concentration of the Adhesive Composition for Electrochemical Element Functional Layer>

[0269] The solid content concentration of the adhesive composition is preferably 10.0 mass % or more, more preferably 15.5 mass % or more, and is preferably 50.0 mass % or less, more preferably 35.0 mass % or less, and further preferably 25.0 mass % or less.

[0270] When the solid content concentration of the adhesive composition is not less than the above lower limit, the number of coating times when forming the functional layer can be reduced, thereby improving the productivity of the functional layer.

[0271] On the other hand, when the solid content concentration of the adhesive composition is equal to or less than the above upper limit, the long-term redispersibility and short-term redispersibility of the adhesive composition can be improved.

[0272] <Method for Preparing an Adhesive Composition for an Electrochemical Element Functional Layer>

[0273] The binder composition can be prepared by, for example, mixing the aforementioned granular polymer, water-soluble polymer, water, a granular binder material as needed, an amine compound, and other ingredients. Furthermore, when the granular polymer, water-soluble polymer, or granular binder material are prepared by polymerizing a monomer composition in an aqueous solvent, the granular polymer, water-soluble polymer, or granular binder material can be directly mixed with the other ingredients in the form of an aqueous dispersion.

[0274] The mixing method of the above components is not particularly limited. In order to disperse the components efficiently, it is preferred to use a dispersing machine as a mixing device for mixing. Furthermore, the dispersing machine is preferably a device capable of uniformly dispersing and mixing the above components. Examples of dispersing machines include ball mills, sand mills, pigment dispersing machines, attritors, ultrasonic dispersers, homogenizers, and planetary mixers.

[0275] (Slurry composition for electrochemical element functional layer)

[0276] The slurry composition for an electrochemical device functional layer of the present invention comprises the binder composition of the present invention and non-conductive heat-resistant particles. Specifically, the slurry composition of the present invention comprises a granular polymer, a water-soluble polymer, non-conductive heat-resistant particles, and water, and may optionally further comprise a granular binder, an amine compound, and the like.

[0277] The slurry composition as described above can enable the functional layer to exhibit excellent adhesiveness.

[0278] In addition, the slurry composition of the present invention may optionally further contain other components in addition to the above-mentioned components.

[0279] <Non-conductive heat-resistant particles>

[0280] The non-conductive heat-resistant particles contained in the slurry composition of the present invention can impart heat resistance to the functional layer.

[0281] Here, in this specification, "non-conductive heat-resistant particles" refer to non-conductive fine particles having a heat-resistant temperature of 200° C. or higher, and "heat-resistant temperature" refers to a temperature at which no substantial physical changes such as thermal deformation occur.

[0282] The non-conductive heat-resistant particles are not particularly limited as long as they are fine particles having a heat-resistant temperature of 200° C. or higher, are electrochemically stable, and have electrical insulating properties, but are preferably inorganic particles.

[0283] Since inorganic particles have a large specific gravity, when a functional layer is formed, for example, by applying a slurry composition containing inorganic particles onto a substrate, the granular polymer tends to protrude more than the inorganic particles on the surface in the thickness direction of the functional layer, thereby improving the adhesion of the functional layer.

[0284] Here, as materials for the inorganic particles, preferably materials that are stable and electrochemically stable in the use environment of the electrochemical device are preferred. Examples include: oxide particles such as aluminum oxide (Alumina), aluminum oxide hydrates (boehmite (AlOOH)), gibbsite (Al(OH3)), silicon oxide, magnesium oxide (Magnesia), magnesium hydroxide, calcium oxide, titanium oxide (Titania), barium titanate (BaTiO3), zirconium oxide (ZrO), and aluminum oxide-silicon dioxide composite oxides; nitride particles such as aluminum nitride and boron nitride; covalently bonded crystal grains such as silicon and diamond; insoluble ionic crystal particles such as barium sulfate, calcium fluoride, and barium fluoride; and clay particles such as talc and montmorillonite. Among these, aluminum oxide, aluminum oxide hydrates (boehmite), magnesium hydroxide, and barium sulfate are more preferred, and aluminum oxide is even more preferred. In addition, these particles can be subjected to element substitution, surface treatment, solid solution formation, etc. as needed.

[0285] These inorganic particles may be used alone or in combination of two or more at any ratio.

[0286] The volume particle size D50 of the non-conductive heat-resistant particles is preferably 0.1 μm or more, more preferably 0.15 μm or more, further preferably 0.2 μm or more, and preferably 1.5 μm or less, more preferably 1.0 μm or less, and further preferably 0.8 μm or less.

[0287] If the volume particle size D50 of the non-conductive heat-resistant particles is greater than the above lower limit, the non-conductive heat-resistant particles are densely packed in the functional layer. This further suppresses the reduction in ion conductivity in the functional layer and improves the electrochemical characteristics (particularly output characteristics) of the electrochemical element.

[0288] On the other hand, when the volume particle size D50 of the non-conductive heat-resistant particles is equal to or less than the upper limit, the functional layer can exhibit excellent heat resistance even when the functional layer is made thinner.

[0289] In this specification, the volume particle size D50 of the non-conductive heat-resistant particles refers to the particle size at which the cumulative volume calculated from the smallest particle size in the particle size distribution (volume basis) measured by laser diffraction method accounts for 50%, and can be measured by the method described in Examples.

[0290] <Other ingredients>

[0291] The slurry composition of the present invention may optionally contain any other components, without particular limitation, as long as they do not affect the electrochemical reaction in the electrochemical element, and examples thereof include dispersants, thickeners, etc. These other components may be used alone or in combination of two or more.

[0292] <Volume Ratio of Granular Polymer to Non-Conductive Heat-Resistant Particles>

[0293] The volume ratio of the granular polymer to the non-conductive heat-resistant particles in the slurry composition (volume of the granular polymer / volume of the non-conductive heat-resistant particles) is preferably 1 / 99 or more, more preferably 3 / 97 or more, further preferably 5 / 95 or more, further preferably 8 / 92 or more, preferably 60 / 40 or less, more preferably 50 / 50 or less, further preferably 40 / 60 or less, further preferably 30 / 70 or less.

[0294] When the volume ratio in the slurry composition is equal to or greater than the lower limit, the particulate polymer is sufficiently present in the functional layer formed using the slurry composition, and thus the adhesiveness of the functional layer can be improved.

[0295] On the other hand, when the volume ratio in the slurry composition is equal to or less than the upper limit, the non-conductive heat-resistant particles are sufficiently present in the functional layer formed using the slurry composition, and thus the heat resistance of the functional layer can be improved.

[0296] <Content of Each Component in the Slurry Composition for Electrochemical Element Functional Layer>

[0297] The content of the water-soluble polymer in the slurry composition is preferably 1.0 parts by mass or more, more preferably 1.5 parts by mass or more, and preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, per 100 parts by mass of the non-conductive heat-resistant particles.

[0298] When the content of the water-soluble polymer in the slurry composition is not less than the above lower limit, the heat resistance of the functional layer can be improved.

[0299] On the other hand, when the content of the water-soluble polymer in the slurry composition is not more than the above upper limit, an increase in the resistance value of the electrochemical element can be effectively suppressed, thereby improving the cycle characteristics of the electrochemical element.

[0300] In the case where the slurry composition contains a granular binder, the content of the granular binder in the slurry composition is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, further preferably 2.0 parts by mass or more, further preferably 2.2 parts by mass or more, further preferably 2.5 parts by mass or more, preferably 6.0 parts by mass or less, more preferably 5.5 parts by mass or less, further preferably 5.0 parts by mass or less, further preferably 4.5 parts by mass or less, relative to 100 parts by mass of the granular polymer.

[0301] When the content of the particulate binder in the slurry composition is not less than the above lower limit, the particulate binder is sufficiently present in the functional layer formed using the slurry composition, and thus the adhesiveness of the functional layer can be improved.

[0302] On the other hand, when the content of the particulate binder in the slurry composition is below the upper limit, the non-conductive heat-resistant particles are sufficiently present in the functional layer formed using the slurry composition, thereby improving the heat resistance of the functional layer.

[0303] <Solid Content Concentration of Slurry Composition for Electrochemical Element Functional Layer>

[0304] The solid content concentration of the slurry composition is preferably 10.0% by mass or more, more preferably 20.0% by mass or more, and is preferably 70.0% by mass or less, more preferably 50.0% by mass or less.

[0305] <Method for Preparing Slurry Composition for Electrochemical Element Functional Layer>

[0306] The slurry composition is not particularly limited and can be prepared, for example, by appropriately mixing a binder composition and non-conductive heat-resistant particles. Alternatively, the slurry composition can be prepared by using a composition containing non-conductive heat-resistant particles, which optionally contains a water-soluble polymer, a granular polymer, water, or other components, and appropriately mixing the composition containing non-conductive heat-resistant particles with the binder composition.

[0307] The method for mixing the above components is not particularly limited. In order to disperse the components efficiently, a dispersing machine is preferably used as a mixing device for mixing. Furthermore, the dispersing machine is preferably a device capable of uniformly dispersing and mixing the above components. Examples of dispersing machines include ball mills, sand mills, pigment dispersing machines, attritors, ultrasonic dispersers, homogenizers, and planetary mixers.

[0308] (Laminate for electrochemical device)

[0309] The electrochemical device laminate of the present invention comprises a substrate and a functional layer formed on the substrate, wherein the functional layer is formed using the binder composition of the present invention or the slurry composition of the present invention. The binder composition and the slurry composition of the present invention (hereinafter sometimes collectively referred to as "functional layer composition") can form a functional layer with excellent adhesion. Therefore, if a laminate having a functional layer formed using these compositions is provided, the electrochemical properties (e.g., cycle characteristics and output characteristics) of an electrochemical device having the electrochemical device laminate can be improved.

[0310] <Base Material>

[0311] The substrate is not particularly limited. For example, when the functional layer is used as a component constituting a portion of a separator, a separator substrate can be used as the substrate. Furthermore, when the functional layer is used as a component constituting a portion of an electrode, an electrode substrate in which an electrode composite material layer is formed on a current collector can be used as the substrate. The use of a laminate obtained by forming a functional layer on a substrate using a composition for a functional layer is not particularly limited. For example, the functional layer can be formed on a separator substrate and used directly as a battery component such as a separator, or the functional layer can be formed on an electrode substrate and used directly as an electrode.

[0312] <<Spacer Base Material>>

[0313] As the spacer substrate forming the functional layer, there is no particular limitation, and the spacer substrate described in Japanese Patent Application Publication No. 2012-204303 can be used. Among these, from the aspect of being able to make the overall film thickness of the spacer thinner so as to increase the ratio of the electrode active material in the electrochemical element and thus increase the capacity per unit volume, it is preferred that the microporous film be formed by a resin of a polyolefin system (polyethylene, polypropylene, polybutene, polyvinyl chloride). In addition, the spacer substrate can also include in a part thereof any layer capable of exerting a desired function in addition to the functional layer.

[0314] <<Electrode Base Material>>

[0315] As the electrode substrate (positive electrode substrate and negative electrode substrate) forming the functional layer, it is not particularly limited, and an electrode substrate having an electrode composite material layer formed on the current collector can be cited. Here, the components in the current collector and the electrode composite material layer (such as electrode active material (positive electrode active material, negative electrode active material) and electrode composite material layer binding material (positive electrode composite material layer binding material, negative electrode composite material layer binding material) etc.) and the method for forming the electrode composite material layer on the current collector can use known ones, and can use those described in, for example, Japanese Patent Application Laid-Open No. 2013-145763. In addition, the electrode substrate can include any layer having a desired function other than the functional layer in a part thereof.

[0316] <Functional Layer>

[0317] The functional layer can be formed on the above-mentioned substrate using the functional layer composition of the present invention. Here, when the functional layer is formed using the binder composition of the present invention, the functional layer contains at least the above-mentioned granular polymer, water-soluble polymer, granular binder used as needed, amine compound, and other components. When the functional layer is formed using the slurry composition of the present invention, the functional layer contains at least the above-mentioned granular polymer, water-soluble polymer, non-conductive heat-resistant particles, granular binder used as needed, amine compound, and other components. In addition, the components contained in the functional layer are the components contained in the above-mentioned functional layer composition, and the preferred ratio of these components is the same as the preferred ratio of the components in the functional layer composition.

[0318] <<Method for Forming Functional Layer>>

[0319] The method for forming a functional layer on a substrate using the composition for a functional layer is not particularly limited, and examples thereof include:

[0320] 1) A method of coating the surface of the substrate with a composition for a functional layer and then drying the composition;

[0321] 2) A method of dipping the substrate in the functional layer composition and then drying it;

[0322] 3) A method in which a composition for a functional layer is applied onto a release substrate, dried to form a functional layer, and the obtained functional layer is transferred to the surface of the substrate.

[0323] In addition, the functional layer may be formed on only one side of the substrate or on both sides of the substrate.

[0324] Here, the release substrate is not particularly limited, and a known release substrate can be used.

[0325] Among these, method 1) above is preferred because the thickness of the functional layer can be easily controlled. Furthermore, method 1) above may include, for example, a step of applying a functional layer composition to a substrate (a coating step) and a step of drying the functional layer composition applied to the substrate to form the functional layer (a functional layer forming step).

[0326] -Coating process-

[0327] In the coating step, the method for coating the functional layer composition on the substrate is not particularly limited, and examples thereof include doctor blade method, reverse roll method, direct roll method, gravure method, extrusion method, and brush coating method.

[0328] Functional layer formation process

[0329] In the functional layer formation step, the method for drying the functional layer composition on the substrate is not particularly limited, and known methods can be used. Examples include drying with warm air, hot air, or low-humidity air; vacuum drying; and drying using irradiation with infrared rays, electron beams, or the like. Drying conditions are not particularly limited, but the drying temperature is preferably 50°C to 150°C, and the drying time is preferably 1 minute to 30 minutes.

[0330] Here, when a functional layer is formed on a substrate using the adhesive composition of the present invention as a composition for a functional layer, an adhesive layer serving as the functional layer can be obtained.

[0331] Furthermore, when the slurry composition of the present invention is used as a composition for a functional layer to form a functional layer on a substrate, a single layer can be obtained as the functional layer that simultaneously functions as a heat-resistant layer for improving the heat resistance of the substrate and as an adhesive layer for firmly bonding components to each other.

[0332] Furthermore, as described above, a substrate having a functional layer formed using the slurry composition of the present invention can be produced in shorter steps and time than a substrate having a conventional heat-resistant layer and an adhesive layer, and thus has high productivity.

[0333] <<Thickness of functional layer>>

[0334] Here, in the functional layer formed using the slurry composition of the present invention, a plurality of non-conductive heat-resistant particles are generally arranged in a stacked manner in the thickness direction of the functional layer. Moreover, the thickness of the layer formed by stacking the non-conductive heat-resistant particles in the thickness direction of the functional layer (hereinafter sometimes referred to as the "heat-resistant particle layer") is preferably 0.5 μm or more, more preferably 0.8 μm or more, further preferably 1 μm or more, preferably 6 μm or less, more preferably 5 μm or less, and further preferably 4 μm or less.

[0335] When the thickness of the heat-resistant particle layer is not less than the above lower limit, the heat resistance of the functional layer becomes extremely good.

[0336] On the other hand, when the thickness of the heat-resistant particle layer is equal to or less than the upper limit, the ion diffusibility of the functional layer can be ensured, and the electrochemical characteristics (particularly output characteristics) of the electrochemical device can be further sufficiently improved.

[0337] In addition, in this specification, "the thickness of the heat-resistant particle layer" can be measured using the method described in Examples of this specification.

[0338] The maximum thickness of the functional layer formed on the substrate is preferably 1.0 μm or more, more preferably 1.5 μm or more, further preferably 2.0 μm or more, particularly preferably 2.5 μm or more, most preferably 5.0 μm or more, preferably 10.0 μm or less, more preferably 9.0 μm or less, further preferably 8.0 μm or less.

[0339] In this specification, the "maximum thickness of the functional layer" can be measured using, for example, a field emission scanning electron microscope (FE-SEM).

[0340] (Electrochemical Components)

[0341] The electrochemical device of the present invention includes the electrochemical device laminate of the present invention. Such an electrochemical device can exhibit excellent cycle characteristics.

[0342] Furthermore, the electrochemical device of the present invention only needs to include at least the laminate of the present invention, and therefore, may include components other than the laminate of the present invention as long as the effects of the present invention are not significantly impaired.

[0343] Furthermore, the electrochemical device of the present invention is not particularly limited, and is, for example, a lithium ion secondary battery or an electric double layer capacitor, and is preferably a lithium ion secondary battery.

[0344] Here, a lithium ion secondary battery as an example of the electrochemical element of the present invention is described below. The lithium ion secondary battery of the present invention has the above-mentioned laminate of the present invention. More specifically, the lithium ion secondary battery has a positive electrode, a negative electrode, a separator with a functional layer formed on a separator substrate (laminate of the present invention), and an electrolyte. The functional layer can be formed only on a single surface of the separator substrate or on both surfaces of the separator substrate.

[0345] In the following example, the functional layer is formed on the separator substrate, but the functional layer may also be formed on the electrode substrate.

[0346] Moreover, in the lithium ion secondary battery of the present invention, the positive electrode and the separator substrate and / or the negative electrode and the separator substrate are firmly bonded in the electrolyte through the functional layer. Therefore, the expansion of the distance between the pole plates of the electrode accompanied by repeated charge and discharge is also suppressed, and battery characteristics such as cycle characteristics become good. In addition, in the lithium ion secondary battery, the heat resistance of the separator substrate is improved through the functional layer. Furthermore, compared with the case of using a separator with a conventional heat-resistant layer and an adhesive layer, the lithium ion secondary battery can shorten the time required to manufacture the separator, thereby manufacturing it with high productivity.

[0347] Furthermore, as the positive electrode, negative electrode, and electrolyte solution described above, known positive electrodes, negative electrodes, and electrolyte solutions used in lithium-ion secondary batteries can be used.

[0348] <Positive and negative electrodes>

[0349] Specifically, as electrodes (positive and negative electrodes), electrodes formed by forming an electrode composite material layer on a current collector can be used. In addition, as current collectors, current collectors formed of metal materials such as iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. can be used. Among these, as current collectors for negative electrodes, current collectors formed of copper are preferably used. In addition, as current collectors for positive electrodes, current collectors formed of aluminum are preferably used. Furthermore, as electrode composite material layers, layers comprising an electrode active material and a binder can be used.

[0350] <Separator with Functional Layer (Laminate)>

[0351] The separator with a functional layer can be produced by, for example, forming the functional layer on the separator substrate using the method for forming the functional layer described above.

[0352] Here, the separator substrate is not particularly limited, and for example, the separator substrates described in Japanese Patent Application Laid-Open No. 2012-204303 can be used. Among these, microporous membranes composed of polyolefin resins (polyethylene, polypropylene, polybutylene, polyvinyl chloride) are preferred from the viewpoint of being able to reduce the overall thickness of the separator with a functional layer, thereby increasing the ratio of the electrode active material in the lithium-ion secondary battery and thus increasing the capacity per unit volume.

[0353] <Electrolyte>

[0354] As the electrolyte, an organic electrolyte in which a supporting electrolyte is dissolved in an organic solvent is generally used. As the supporting electrolyte, for example, a lithium salt can be used 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. Because they are easily soluble in solvents and show a high degree of dissociation, LiPF6, LiClO4, and CF3SO3Li are particularly preferred. 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.

[0355] As an organic solvent used in the electrolyte, there is no particular limitation as long as it is an organic solvent that can dissolve the supporting electrolyte. For example, in lithium ion secondary batteries, preferably used are: carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), ethyl methyl carbonate (ethyl methyl carbonate (EMC)), and vinylene carbonate; esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfur-containing compounds such as cyclopentane and dimethyl sulfoxide, etc.

[0356] Alternatively, a mixture of these organic solvents may be used. Carbonates are particularly preferred due to their high dielectric constant and wide stable potential range. Generally, the lower the viscosity of the organic solvent used, the higher the lithium ion conductivity. Therefore, the lithium ion conductivity can be adjusted by adjusting the type of organic solvent.

[0357] In addition, the concentration of the electrolyte in the electrolytic solution can be appropriately adjusted. In addition, known additives can also be added to the electrolytic solution.

[0358] <Method for Manufacturing Lithium-Ion Secondary Battery>

[0359] The lithium ion secondary battery as the electrochemical element of the present invention can be manufactured in the following manner, for example: the above-mentioned positive and negative electrodes are overlapped across the spacer (laminate of the present invention) with a functional layer, and are wound, folded, etc. as needed and placed in a battery container, and an electrolyte is injected into the battery container for sealing. Here, as needed, porous metal mesh, fuse, PTC element and other anti-overcurrent elements, guide plates, etc. can be placed in a battery container to prevent the pressure inside the battery from rising and overcharging and discharging. The shape of the battery can be any one of, for example, coin-shaped, button-shaped, sheet-shaped, cylindrical, square, flat, etc.

[0360] Example

[0361] 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" indicating amounts are based on mass unless otherwise specified.

[0362] In addition, in a polymer produced by copolymerizing multiple monomers, unless otherwise specified, the proportion of a structural unit 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.

[0363] In the embodiments and comparative examples, the glass transition temperature of the granular polymer, the volume particle size D50 of the granular polymer, the volume particle size D50 of the granular adhesive material, the volume particle size D50 of the non-conductive heat-resistant particles, the true specific gravity of the granular polymer, the average roundness and median roundness of the granular polymer, the weight-average molecular weight of the water-soluble polymer, the pH of the adhesive composition, the viscosity of the adhesive composition, the thickness of the functional layer (heat-resistant particle layer), the volume ratio of the non-conductive heat-resistant particles to the granular polymer, the long-term redispersibility of the adhesive composition, the adhesion of the functional layer, and the resistance of the granular polymer in the functional layer to falling off are measured and evaluated by the following methods.

[0364] <Glass Transition Temperature of Granular Polymer>

[0365] The particulate polymers prepared in Examples and Comparative Examples were used as measurement samples, and the glass transition temperatures of the particulate polymers were measured.

[0366] Specifically, 10 mg of a sample was weighed into an aluminum pan and measured using a differential thermal analyzer ("EXSTAR DSC6220" manufactured by Seiko NanoTechnology, Inc.) under the conditions specified in JIS Z8703, within a measurement temperature range of -100°C to 500°C, at a heating rate of 10°C / minute, to obtain a differential scanning calorimetry (DSC) curve. An empty aluminum pan was used as a reference. In the resulting differential scanning calorimetry (DSC) curve, the intersection of the baseline immediately before the endothermic peak of the DSC curve with a differential signal (DDSC) of 0.05 mW / min / mg or greater and the tangent to the DSC curve at the first inflection point after the endothermic peak was determined as the glass transition temperature (°C) of the particulate polymer.

[0367] In addition, the glass transition temperature of the polyester polymer obtained in Example 18 was determined by the same method as above, and the determined glass transition temperature was made the glass transition temperature of the particulate polymer in Example 18.

[0368] <Volume particle size D50 of granular polymer>

[0369] The granular polymers prepared in Examples and Comparative Examples were used as measurement samples, and the volume particle size D50 of the granular polymers was measured.

[0370] Specifically, a 0.1 g equivalent of the sample to be measured was weighed and placed in a beaker. 0.1 mL of an aqueous solution of alkylbenzenesulfonic acid ("DRIWEL" manufactured by Fujifilm Corporation) was added as a dispersant. 10 to 30 mL of a diluent ("ISOTON II" manufactured by Beckman Coulter Co., Ltd.) was further added to the beaker and dispersed for 3 minutes using a 20 W ultrasonic disperser. The sample was then measured using a particle size analyzer ("Multisizer" manufactured by Beckman Coulter Co., Ltd.) under the following conditions: pore size: 20 μm, medium: ISOTON II, and number of particles measured: 100,000. In the particle size distribution (volume basis) of the particulate polymer obtained by the measurement, the particle size D50 at which the cumulative volume, calculated from the smallest particle size, reaches 50% was defined as the volume particle size D50 of the particulate polymer.

[0371] <Volume particle size D50 of granular binder material>

[0372] The volume particle size D50 of the granular binder materials prepared in Examples and Comparative Examples was measured by laser diffraction.

[0373] Specifically, an aqueous dispersion solution containing the prepared particulate binder (with a solids concentration adjusted to 0.1% by mass) was used as a sample. Measurements were then performed using a laser diffraction particle size distribution analyzer ("LS-230," manufactured by Beckman Coulter, Inc.). In the particle size distribution (volume basis) of the particulate binder obtained through the measurement, the particle size D50 at which the cumulative volume, calculated from the smallest particle size, reached 50% was defined as the volume particle size D50 of the particulate binder.

[0374] <Volume Particle Size D50 of Non-Conductive Heat-Resistant Particles>

[0375] The volume particle size D50 of the non-conductive heat-resistant particles used in Examples and Comparative Examples was measured by a laser diffraction method.

[0376] Specifically, in the particle size distribution (volume basis) of the non-conductive heat-resistant particles measured by laser diffraction, the particle size (D50) at which the cumulative volume calculated from the smaller particle size accounts for 50% is defined as the volume particle size D50 of the non-conductive heat-resistant particles.

[0377] <True Specific Gravity of Granular Polymer>

[0378] The true specific gravity of the granular polymers prepared in Examples and Comparative Examples was measured using a pycnometer method in accordance with JIS K8837.

[0379] Specifically, the true specific gravity of the particulate polymer at a temperature of 25° C. was measured using a pycnometer (BELPYCNO L, manufactured by Microchip Baier Co., Ltd.).

[0380] <Average Circularity and Median Circularity of Granular Polymer>

[0381] The granular polymers prepared in Examples and Comparative Examples were used as measurement samples, and the average circularity and median circularity of the granular polymers were measured.

[0382] Specifically, 10mL of ion exchange water is added in advance in a container, 0.02g of a surfactant (alkylbenzene sulfonic acid) as a dispersant is added thereto, 0.02g of a measurement sample is further added, and an ultrasonic disperser is used to disperse the sample for 3 minutes at 60W (Watt). The concentration of the measurement sample during measurement is adjusted to 3000 to 10000 / μL, and for 1000 to 10000 measurement samples with a circle equivalent diameter of more than 0.4μm, a flow-type particle image analyzer (System of Sysmex Co., Ltd., "FPIA-3000") is used for measurement. In addition, circularity is as shown in the following formula (I), and average circularity is the value averaged, and median circularity is the median circularity.

[0383] Circularity = circumference of a circle equal to the projected area of ​​the granular polymer / circumference of the projected image of the granular polymer (I)

[0384] <Weight Average Molecular Weight of Water-Soluble Polymer>

[0385] The weight-average molecular weight of the water-soluble polymers prepared in Examples and Comparative Examples was determined using a gel permeation chromatograph equipped with a multi-angle light scattering detector (DAWNHELEOS II, manufactured by Wyatt Technologies) and a differential refractive index detector (Optilab T-rEX, manufactured by Wyatt Technologies). The measurement conditions are as follows.

[0386] Column: TSKgel GMPW XL 2 roots ( (Made by Tosoh Corporation)

[0387] Solvent: 0.1M sodium nitrate aqueous solution

[0388] Flow rate: 0.5 mL / mm

[0389] Column temperature: 45°C

[0390] Sample injection volume: 0.2mL

[0391] Preparation of measurement samples: First, dry and solidify an aqueous solution containing a water-soluble polymer. Next, add 10 ml of a 0.1 M sodium nitrate aqueous solution to 100 mg of the dried water-soluble polymer and gently stir at room temperature to dissolve the water-soluble polymer. Filter the resulting solution through a 0.5 μm filter to obtain a measurement sample.

[0392] <pH of Adhesive Composition>

[0393] The pH of the adhesive compositions obtained in Examples and Comparative Examples was measured using a pH meter.

[0394] Specifically, a tabletop pH meter (F-51 manufactured by HORIBA) was calibrated with pH standard solutions (pH 4, pH 7, and pH 9) at 25°C, and the pH of a sample (adhesive composition) at 25°C was measured using the meter.

[0395] <Viscosity of Adhesive Composition>

[0396] The viscosity of the adhesive compositions obtained in Examples and Comparative Examples was measured using a B-type viscometer.

[0397] Specifically, the viscosity of the sample (adhesive composition) was measured at a temperature of 25° C. and a rotation speed of 60 rpm (rotor: L adapter) using a B-type viscometer (TVB-10M, manufactured by Toki Sangyo Co., Ltd.) in accordance with JIS K7117-1.

[0398] <Thickness of Functional Layer (Heat-Resistant Particle Layer)>

[0399] The thickness of the functional layer (heat-resistant particle layer) was calculated from the cross-section of the separator with the functional layer observed using a field emission scanning electron microscope (FE-SEM, JEOL Ltd., "JSM-7800 Prime," detector: BED-C, accelerating voltage: 5 kV, magnification: 500x). The thickness of the functional layer (heat-resistant particle layer) was calculated from the resulting SEM image. The thickness of the functional layer (heat-resistant particle layer) was defined as the distance from the surface of the separator substrate on which the functional layer was formed to the non-conductive heat-resistant particle farthest away in the vertical direction.

[0400] <Volume Ratio of Granular Polymer to Non-Conductive Heat-Resistant Fine Particles>

[0401] The volume ratio of the granular polymer to the non-conductive heat-resistant particles (alumina) was calculated based on the amount of the granular polymer and the non-conductive heat-resistant particles (alumina) added during the preparation of the slurry composition (volume of the granular polymer / volume of the non-conductive heat-resistant particles). 3 Perform calculations.

[0402] <Long-term Redispersibility of Binder Composition>

[0403] First, 5 kg of the adhesive composition obtained in the Examples and Comparative Examples was placed in a 5 L cylindrical container and allowed to stand for 30 days. Particulate polymer precipitated in the adhesive composition after 30 days of standing. The liquid phase of the adhesive composition after 30 days of standing was collected and the solid content concentration in the liquid phase was measured. It was confirmed that the solid content concentration was lower than before standing (immediately after the adhesive composition was prepared).

[0404] Next, after standing for 30 days, the adhesive composition was redispersed using a universal ball mill (rotational speed: at an inverter frequency of 30 Hz (maximum 60 Hz)). The liquid phase was sampled every 15 minutes and the solid content concentration in the liquid phase was measured. The time required for the solid content concentration in the liquid phase to return to the pre-standing solid content concentration was determined and evaluated according to the following criteria. The shorter the time required for the solid content concentration in the liquid phase to return to the pre-standing solid content concentration, the better the long-term redispersibility of the adhesive composition.

[0405] A: Less than 15 minutes

[0406] B: More than 15 minutes and less than 30 minutes

[0407] C: More than 30 minutes

[0408] <Adhesion of Functional Layer>

[0409] The separators with functional layers produced in the Examples and Comparative Examples were observed using a laser displacement microscope (Keyence Corporation, Model: VK-X1000). Ten random 100 μm square areas on the functional layer surface were measured, and the arithmetic mean height Sa of the functional layer surface was calculated and evaluated according to the following criteria. A larger arithmetic mean height Sa indicates a larger contact area with the battery component, resulting in better adhesion.

[0410] A: Arithmetic mean height Sa is 1.5 μm or more

[0411] B: Arithmetic mean height Sa is 1.2 μm or more and less than 1.5 μm

[0412] C: Arithmetic mean height Sa is 1.0 μm or more and less than 1.2 μm

[0413] D: Arithmetic mean height Sa is less than 1.0 μm

[0414] <Resistance to Falling Off of Particulate Polymer in Functional Layer>

[0415] Using a field emission scanning electron microscope (FE-SEM, JEOL Ltd., "JSM-7800 Prime", detector: BED-C, accelerating voltage: 5 kV, magnification: 500x), images with a field of view of 186 μm in length and 248 μm in width were obtained at any five locations (10 locations in total) on the front and back sides of the spacers with functional layers produced in the examples and comparative examples.

[0416] Next, the resulting 10 images were binarized to determine the ratio of the area of ​​the particulate polymer to the area of ​​the particle-shedding portion. Specifically, using image analysis software ("WinROOF," manufactured by Mitani Shoji Co., Ltd.), the enhancement conditions were set to "brightness: -30" and "contrast: +70," a 7×7 filter, and two thresholds. Binarization was performed (threshold 38) to obtain a binary image. From the resulting binarized image, the ratio of the combined area of ​​the particulate polymer and the particle-shedding portion per unit area of ​​the functional layer surface, when viewed from above, was determined. The average of the 10 ratios was taken as S1 (%).

[0417] Next, the enhancement conditions were changed to "Brightness: +30" and "Contrast: +70," and a binarized image was obtained in the same manner as above. Based on the resulting binarized image, the ratio of the area of ​​the particle-shedding portion per unit area of ​​the functional layer surface was calculated when viewing the surface of the functional layer from above. The average of the ratios at 10 locations was taken as S2 (%).

[0418] Then, using the following formula (II), the ratio of the area of ​​the particle shedding portion to the total area of ​​the granular polymer and the particle shedding portion is calculated. The lower the area ratio of the particle shedding portion, the better the granular polymer remains in the functional layer (the more effectively the granular polymer is suppressed from shedding).

[0419] Area ratio of particle shedding portion (%) = S2 / S1×100 (II)

[0420] A: The area ratio of the particle shedding part is less than 0.2%

[0421] B: The area ratio of the particle-shedding portion is 0.2% or more and less than 1%

[0422] C: The area ratio of the particle falling part is 1% or more

[0423] <Long-term aggregation inhibition of adhesive composition>

[0424] First, 100 g of the adhesive composition obtained in the Examples and Comparative Examples was filtered through a 635-mesh sieve (material: SUS316, wire diameter: 20 μm, pore size: 20 μm) cut into 10 cm squares. The 635-mesh sieve was then heat-dried in an oven at 105°C for 30 minutes. Then, using the weight "A" g of the unused 635-mesh sieve, the weight "B" g of the heat-dried 635-mesh sieve (with aggregates in the adhesive composition adhering thereto), the weight "C" g (100 g) of the adhesive composition, and the solids concentration "D" % of the adhesive composition, the amount of aggregates "M1" immediately after preparation was calculated using the following formula (III).

[0425] M1=[(BA) / (C×D / 100)] (III)

[0426] Next, 5 kg of the adhesive composition obtained in the examples and comparative examples was placed in a 5 L cylindrical container and allowed to stand for 30 days. In addition, granular polymer precipitated in the adhesive composition after standing for 30 days. Next, the adhesive composition after standing for 30 days was redispersed using a universal ball mill (rotation speed: rotation speed at an inverter frequency of 30 Hz (maximum 60 Hz)) until the solid content concentration of the liquid phase, which had been reduced due to the precipitation of the granular polymer, returned to the solid content concentration before standing. 100 g of the redispersed adhesive composition was filtered using a 635 mesh sieve in the same manner as above, and the 635 mesh sieve was heat-dried in an oven at 105°C for 30 minutes. Then, using the weight "a" g of the unused 635-mesh sieve, the weight "b" g of the 635-mesh sieve after heat drying (with agglomerates in the adhesive composition attached, etc.), the weight "c" g (100 g) of the adhesive composition, and the solid content concentration "d" % of the adhesive composition, the amount of agglomerates "M2" after standing for 30 days is calculated by the following formula (IV).

[0427] M2=[(ba) / (c×d / 100)] (IV)

[0428] Then, the amount of change in the aggregates of the adhesive composition was calculated using the following formula (V).

[0429] Agglomerate change (%) = M2 / M1×100 (V)

[0430] The lower the value of the aggregate change amount, the better the long-term aggregation suppression property of the adhesive composition.

[0431] A: The change in condensate is less than 90%

[0432] B: The change in aggregate is 90% or more and less than 110%

[0433] C: The change in condensate is 110% or more

[0434] (Example 1)

[0435] <Preparation of Granular Polymer>

[0436] [Preparation of Monomer Composition]

[0437] A monomer composition was prepared by mixing 72.8 parts of styrene as an aromatic monovinyl monomer, 16.7 parts of n-butyl acrylate as an alkyl (meth)acrylate monomer, and 10 parts of glycidyl methacrylate and 0.5 parts of ethylene glycol dimethacrylate as crosslinking monomers.

[0438] [Preparation of Metal Hydroxides]

[0439] To an aqueous solution of 10.0 parts of magnesium chloride dissolved in 200 parts of ion-exchanged water, an aqueous solution of 7.0 parts of sodium hydroxide dissolved in 50 parts of ion-exchanged water was slowly added with stirring to prepare a colloidal dispersion containing magnesium hydroxide as a metal hydroxide.

[0440] [Suspension polymerization method]

[0441] The granular polymer was prepared by suspension polymerization. Specifically, the monomer composition obtained as described above was added to the colloidal dispersion containing magnesium hydroxide. 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 speed of 12,000 rpm for 1 minute using a pipeline emulsifier disperser (manufactured by Pacific Machinery Co., Ltd., "Cavitron") to form droplets of the monomer composition in the colloidal dispersion containing magnesium hydroxide.

[0442] A colloidal dispersion containing magnesium hydroxide and containing droplets of the monomer composition was added to a reactor, heated to 90°C, and subjected to polymerization 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.

[0443] Furthermore, while stirring the aqueous dispersion containing the granular polymer, sulfuric acid was added dropwise at room temperature (25°C) to perform acid washing until the pH reached 6.5 or below. Next, the dispersion was filtered and separated, and 500 parts of ion-exchanged water was added to the resulting solids to form a reslurry. A water washing process (washing, filtration, and dehydration) was repeated 10 times. The resulting solids were then filtered and separated, placed in a dryer container, and dried at 40°C for 48 hours to obtain dried granular polymer. The granular polymer obtained in this manner was solid particles.

[0444] The obtained particulate polymer was used to measure the glass transition temperature of the particulate polymer, the volume particle size D50 of the particulate polymer, the true specific gravity of the particulate polymer, and the average circularity and median circularity of the particulate polymer.

[0445] <Preparation of Aqueous Solution Containing Water-Soluble Polymer>

[0446] In a 10L flask with a rubber stopper, 6335g of ion-exchanged water and 170g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were placed. The mixture was heated to 40°C and the atmosphere was purged with nitrogen at a flow rate of 100mL / min. Next, 1300g of acrylic acid, an acid-group-containing monomer, was injected into the flask via syringe. Then, 180g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator was added to the flask via syringe. The reaction temperature was set to 60°C. Two hours later, to further increase the reaction conversion rate, 90g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 85g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added. Another two hours later, 90g of a 5.0% aqueous solution of ammonium persulfate as a polymerization initiator and 85g of a 2.0% aqueous solution of L-ascorbic acid as a polymerization accelerator were added. After 2 hours, 34 g of a 5% by mass aqueous solution of sodium nitrite as a reaction terminator was added to the flask and stirred. The flask was then cooled to 40° C., placed in an air environment, and 10% by mass ammonia water was used to adjust the pH of the system to 8.0, thereby preparing an aqueous solution containing a water-soluble polymer.

[0447] The weight average molecular weight of the water-soluble polymer was measured using the obtained aqueous solution containing the water-soluble polymer. The results are shown in Table 1.

[0448] <Preparation of Aqueous Dispersion Containing Particulate Binder>

[0449] The granular binder material was prepared as follows.

[0450] First, 70 parts of ion-exchanged water, 0.15 parts of sodium lauryl sulfate (manufactured by Kao Chemical Co., Ltd., "EMAL (registered trademark) 2F") as an emulsifier, and 0.5 parts of ammonium persulfate as a polymerization initiator were supplied to a reactor equipped with a stirrer. The gas phase was replaced with nitrogen, and the temperature was raised to 60°C.

[0451] On the other hand, in another container, 50 parts of ion-exchanged water, 1.0 part of sodium dodecylbenzenesulfonate as a dispersion stabilizer, 94 parts of n-butyl acrylate as an alkyl (meth)acrylate monomer, 2 parts of methacrylic acid as an acid group-containing monomer, and 2 parts of acrylonitrile as a nitrile group-containing monomer, as well as 1 part of allyl methacrylate and 1 part of allyl glycidyl ether as crosslinking monomers were mixed to prepare a monomer composition.

[0452] The resulting monomer composition was continuously added to the aforementioned reactor equipped with a stirrer over a period of 4 hours to allow polymerization to proceed. During the addition, the reaction was conducted at 60°C. After the addition was completed, the mixture was stirred at 70°C for 3 hours, after which the reaction was terminated. This yielded an aqueous dispersion of a granular binder material composed of an acrylic acid-based polymer (ACL).

[0453] The volume particle size D50 of the particulate binder material was measured using the obtained aqueous dispersion containing the particulate binder material. The results are shown in Table 1.

[0454] <Preparation of Adhesive Composition>

[0455] To 100 parts of the granular polymer, 0.2 parts of sodium dodecylbenzenesulfonate ("Neopelex G-15," manufactured by Kao Chemical Co., Ltd.) as an emulsifier, 1.0 parts (solids equivalent) of an aqueous solution containing a water-soluble polymer, and 0.5 parts of 1,2-benzo-4-isothiazolin-3-one as an amine compound were added. Furthermore, 10.0 parts (solids equivalent) of an aqueous dispersion containing a granular binder were added and mixed. An appropriate amount of ion-exchanged water was then added to obtain a binder composition having a solids concentration of 20%.

[0456] The pH of the adhesive composition, the viscosity of the adhesive composition, the long-term redispersibility of the adhesive composition, and the long-term aggregation inhibition of the adhesive composition were measured and evaluated using the obtained adhesive composition.

[0457] <Preparation of Composition Containing Non-Conductive Heat-Resistant Particles>

[0458] To 100 parts of non-conductive heat-resistant alumina particles ("AKP3000" manufactured by Sumitomo Chemical Co., Ltd., volume particle size D50: 0.7 μm) was added 0.5 parts of polyacrylic acid as a dispersant. Ion-exchanged water was added to achieve a solids concentration of 55%, and the mixture was mixed using a ball mill. Furthermore, 4.0 parts of an aqueous dispersion containing a particulate binder and 1.5 parts of an aqueous carboxymethyl cellulose solution as a thickener were added, yielding a composition containing non-conductive heat-resistant particles.

[0459] <Preparation of Slurry Composition>

[0460] The binder composition obtained above was added to the composition containing the non-conductive heat-resistant particles obtained above, and ion-exchanged water was further added so that the solid content concentration became 40%, thereby obtaining a slurry composition.

[0461] In addition, the amount of the composition containing the non-conductive heat-resistant particles added to the adhesive composition is adjusted so that the volume ratio of the granular polymer to the non-conductive heat-resistant particles in the obtained slurry composition (volume of the granular polymer / volume of the non-conductive heat-resistant particles) becomes 10 / 90.

[0462] <Production of Separator with Functional Layer (Laminate)>

[0463] Prepare a polyethylene microporous membrane (thickness: 12 μm) as a separator substrate. Apply the slurry composition obtained as described above to one side of the separator substrate by bar coating. Next, dry the separator 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 separator substrate to produce a separator (laminated body) with a functional layer having a functional layer with a thickness of 2.0 μm on each side of the separator substrate.

[0464] The obtained separator with a functional layer was used to measure and evaluate the thickness of the functional layer (heat-resistant particle layer), the adhesiveness of the functional layer, and the resistance of the particulate polymer in the functional layer to falling off.

[0465] (Example 2)

[0466] In the preparation of the metal hydroxide, the various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that magnesium chloride was changed from 10.0 parts to 15.0 parts and sodium hydroxide was changed from 7.0 parts to 10.5 parts. The results are shown in Table 1.

[0467] (Example 3)

[0468] In the preparation of the metal hydroxide, the various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that the amount of magnesium chloride was changed from 10.0 parts to 7.0 parts and the amount of sodium hydroxide was changed from 7.0 parts to 7.4 parts. The results are shown in Table 1.

[0469] (Example 4)

[0470] In the preparation of the metal hydroxide, the various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that magnesium chloride was changed from 10.0 parts to 3.0 parts and sodium hydroxide was changed from 7.0 parts to 2.1 parts. The results are shown in Table 1.

[0471] (Example 5)

[0472] In the preparation of the monomer composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that 65.0 parts of styrene as an aromatic monovinyl monomer, 10.0 parts of glycidyl methacrylate, and 25.0 parts of ethylene glycol dimethacrylate as crosslinking monomers were mixed to prepare the monomer composition. The results are shown in Table 1.

[0473] (Example 6)

[0474] In the preparation of the monomer composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that 78.0 parts of styrene as an aromatic monovinyl monomer and 10.0 parts of glycidyl methacrylate and 12.0 parts of ethylene glycol dimethacrylate as crosslinking monomers were mixed to prepare the monomer composition. The results are shown in Table 1.

[0475] (Example 7)

[0476] In the preparation of the monomer composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that 72.8 parts of methyl methacrylate and 16.7 parts of n-butyl acrylate were mixed as alkyl (meth)acrylate monomers, and 10 parts of glycidyl methacrylate and 0.5 parts of ethylene glycol dimethacrylate were mixed as crosslinking monomers to prepare the monomer composition. The results are shown in Table 1.

[0477] (Example 8)

[0478] The various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that 8% by mass lithium hydroxide aqueous solution was used instead of 10% by mass ammonia aqueous solution in the preparation of the aqueous solution containing the water-soluble polymer.

[0479] (Example 9)

[0480] The various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that 8% by mass sodium hydroxide aqueous solution was used instead of 10% by mass ammonia aqueous solution in the preparation of the aqueous solution containing the water-soluble polymer.

[0481] (Example 10)

[0482] In the preparation of the aqueous solution containing the water-soluble polymer, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that 1300 g of acrylic acid as the acid group-containing monomer was replaced with 390 g (30.0 mass %) of acrylic acid as the acid group-containing monomer and 910 g (70.0 mass %) of acrylamide as the amide group-containing monomer. The results are shown in Table 1.

[0483] (Example 11)

[0484] In the preparation of the aqueous solution containing the water-soluble polymer, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that 1300 g of acrylic acid as the acid group-containing monomer was replaced with 650 g (50.0 mass %) of acrylic acid and 650 g (50.0 mass %) of 2-acrylamide-2-methylpropanesulfonic acid as the acid group-containing monomer, and that the 10 mass % ammonia aqueous solution was replaced with an 8 mass % sodium hydroxide aqueous solution. The results are shown in Table 1.

[0485] (Example 12)

[0486] In the preparation of the aqueous solution containing a water-soluble polymer, 50 g of carboxymethyl cellulose (Dacel 1220) as a water-soluble polymer was added to 950 g of ion-exchanged water and stirred, and the pH of the system was adjusted to 8.0 using an 8% by mass aqueous sodium hydroxide solution. Various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that the aqueous solution containing the water-soluble polymer was prepared. The results are shown in Table 1.

[0487] (Example 13)

[0488] In the preparation of the adhesive composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that the amount of the aqueous solution containing the water-soluble polymer was changed from 1.0 part to 0.5 part in terms of solid content.

[0489] (Example 14)

[0490] In the preparation of the adhesive composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that the amount of the aqueous solution containing the water-soluble polymer was changed from 1.0 part to 3.0 parts in terms of solid content.

[0491] (Example 15)

[0492] The various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that an aqueous solution prepared as follows was used as the aqueous solution containing the particulate binder.

[0493] <Preparation of Aqueous Dispersion Containing Particulate Binder>

[0494] Into the reactor were placed 150 parts of ion-exchanged water, 25 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate as an emulsifier, 63 parts of styrene as an aromatic monovinyl monomer, 3.5 parts of itaconic acid as an acidic monomer, 1 part of 2-hydroxyethyl acrylate as a hydroxyl-containing monomer, and 0.5 parts of tert-dodecylmercaptan as a molecular weight modifier. The atmosphere in the reactor was then replaced three times with nitrogen before 32.5 parts of 1,3-butadiene as a conjugated diene monomer was added. Polymerization was initiated by adding 0.5 parts of potassium persulfate as a polymerization initiator to the reactor maintained at 60°C, and the polymerization reaction continued while stirring. When the polymerization conversion reached 96%, the reaction was cooled and terminated by adding 0.1 parts of a 10% aqueous solution of hydroquinone as a polymerization terminator. Residual monomers were then removed using a rotary evaporator at 60°C to obtain an aqueous dispersion of a granular binder composed of styrene-butadiene polymer (SBR).

[0495] The volume particle size D50 of the particulate binder material was measured using the obtained aqueous dispersion containing the particulate binder material. The results are shown in Table 1.

[0496] (Example 16)

[0497] In the preparation of the adhesive composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that the solid content concentration of the adhesive composition was changed from 20% to 10%.

[0498] (Example 17)

[0499] In the preparation of the adhesive composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that the solid content concentration of the adhesive composition was changed from 20% to 40%.

[0500] (Example 18)

[0501] In the preparation of the binder composition, a polymer prepared as follows was used as the granular polymer. In the production of the functional layer-bearing separator (laminated body), the thickness of the slurry composition applied to the separator substrate was varied. The same procedures, measurements, and evaluations were performed as in Example 1. The results are shown in Table 1.

[0502] <Preparation of Granular Polymer>

[0503] [Preparation of polyester polymer]

[0504] In a 5-liter four-necked flask equipped with a nitrogen inlet, a dehydration tube, a stirrer, and a thermocouple, 2000 g of BPA-PO (a propylene oxide adduct of bisphenol A, average addition mole number: 2.2 mol) and 800 g of BPA-EO (an ethylene oxide adduct of bisphenol A, average addition mole number: 2.2 mol) as the alcohol component, 600 g of fumaric acid and 500 g of trimellitic anhydride as the carboxylic acid component, and 4 g of dibutyltin oxide were added and reacted at 220°C for 8 hours. The reaction was then continued at 8.3 kPa until the softening point of the reactant (measured by the method described below) reached 150°C, yielding a bulk polyester polymer. The resulting polyester polymer was used to measure its glass transition temperature. The results are shown in Table 1.

[0505] - Softening point determination method -

[0506] Using a high-pressure flow tester (manufactured by Shimadzu Corporation, product name "CFT-500D"), 1 g of a sample was heated at a heating rate of 6°C / minute while a load of 1.96 MPa was applied by the plunger. The sample was extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. A flow tester plunger drop (flow value)-temperature curve was plotted. When the height of this S-shaped curve was defined as h, the temperature corresponding to h / 2 (the temperature at which half of the polymer had flowed out) was defined as the softening point.

[0507] [Preparation of ester wax (melting additive)]

[0508] In a 0.5 L four-necked flask equipped with a nitrogen inlet tube, a stirring blade, and a condenser, 18 g (0.13 mol) of pentaerythritol and 104 g (0.52 mol) of lauric acid were added, and the reaction was carried out at 220° C. for 10 hours while distilling off the generated water under a nitrogen stream. 46.5 g of toluene, 32 g of 2-propanol, and 19 g of a 10% potassium hydroxide aqueous solution containing 2.0 equivalents of potassium hydroxide to the acid value were added, and the mixture was stirred at 70° C. for 30 minutes. After standing for 30 minutes, the aqueous phase was removed to obtain a crude product.

[0509] The crude product was washed four times with 40 parts of ion-exchanged water per 100 parts of the crude product at 70°C to adjust the pH to 7. The solvent was distilled off from the resulting purified product under heating and reduced pressure, and the product was filtered, solidified, and pulverized to obtain 140 g of pentaerythritol tetralaurate (melting point: 44°C) as an ester wax.

[0510] [Solution suspension method]

[0511] The polyester polymer and ester wax are granulated by a dissolution suspension method to obtain a granular polymer.

[0512] Specifically, 100 parts of the polyester polymer obtained above, 10 parts of the ester wax obtained above, and 230 parts of toluene as an organic solvent were dispersed in a ball mill to obtain a liquid composition.

[0513] Separately, 480 parts of an aqueous solution of hydroxyapatite (concentration: 5%), 6 parts of an aqueous solution of sodium dodecylbenzenesulfonate (concentration: 1%), and 120 parts of water were mixed to prepare an aqueous medium.

[0514] The liquid composition is dispersed in the aqueous medium using a homogenizer. The rotor's circumferential speed is adjusted within the range of 6 to 8 m / s. The resulting dispersion is placed at a temperature of 50 to 70°C and a pressure of 30 to 150 mmHg to remove the toluene. The composition after toluene removal is cooled and then washed with 12N hydrochloric acid until the pH reaches 2. The composition is then washed with water, dried, and classified to obtain a granular polymer comprising a polyester polymer and an ester wax. The granular polymer obtained in this manner is solid.

[0515] The obtained granular polymer was used to measure its volume particle size D50, true specific gravity, average circularity, and median circularity. The results are shown in Table 1. The composition of the granular polymer in Example 18 in Table 1 represents the composition of the polyester polymer.

[0516] (Example 19)

[0517] The various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that an aqueous solution of sodium polyacrylate (ARON A-20L, manufactured by Toagosei Co., Ltd.) was used as the aqueous solution containing the water-soluble polymer.

[0518] (Example 20)

[0519] The various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that an aqueous solution of ammonium polyacrylate (ARON A-30, manufactured by Toagosei Co., Ltd.) was used as the aqueous solution containing the water-soluble polymer.

[0520] (Example 21)

[0521] The various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that an aqueous solution of polyacrylic acid (ARON A-10H, manufactured by Toagosei Co., Ltd.) was used as the aqueous solution containing the water-soluble polymer.

[0522] (Comparative Example 1)

[0523] In the preparation of the adhesive composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that the aqueous solution containing the water-soluble polymer was not added to the adhesive composition. The results are shown in Table 1.

[0524] (Comparative Example 2)

[0525] In the preparation of the adhesive composition, various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that a polymer prepared as follows was used as the granular polymer and that 0.2 parts of sodium dodecylbenzenesulfonate ("Neopelex G-15," manufactured by Kao Chemical Co., Ltd.) as an emulsifier was not added. The results are shown in Table 1.

[0526] <Preparation of Granular Polymer>

[0527] [Emulsion polymerization method]

[0528] In a 5 MPa pressure-resistant container equipped with a stirrer, a monomer composition containing 79.9 parts of styrene as an aromatic monovinyl monomer, 18 parts of 2-ethylhexyl acrylate as an alkyl (meth)acrylate monomer, 2 parts of methacrylic acid as an acid group-containing monomer, and 0.1 parts of ethylene glycol dimethacrylate as a crosslinking monomer, 1 part of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator were added, and after sufficient stirring, the mixture was heated to 60° C. to initiate polymerization.

[0529] When the polymerization conversion rate reached 96%, the reaction was terminated by cooling to obtain an aqueous dispersion containing a granular polymer. The granular polymer thus obtained was solid particles.

[0530] The obtained particulate polymer (aqueous dispersion) was used to measure the glass transition temperature, volume particle size D50, true specific gravity, average circularity, and median circularity of the particulate polymer.

[0531] (Comparative Example 3)

[0532] In the preparation of the metal hydroxide, the various operations, measurements, and evaluations were performed in the same manner as in Example 1, except that magnesium chloride was changed from 10.0 parts to 1.5 parts and sodium hydroxide was changed from 7.0 parts to 1.1 parts. The results are shown in Table 1.

[0533] In addition, in Table 1,

[0534] "ST" represents styrene units,

[0535] "BA" represents n-butyl acrylate unit,

[0536] "MMA" means methyl methacrylate units,

[0537] "2EHA" represents 2-ethylhexyl acrylate units,

[0538] "GMA" means glycidyl methacrylate units,

[0539] "EDMA" represents ethylene glycol dimethacrylate units,

[0540] "BPA-PO" represents the propylene oxide adduct unit of bisphenol A,

[0541] "BPA-EO" represents the ethylene oxide adduct unit of bisphenol A,

[0542] "FA" represents fumaric acid unit,

[0543] "TMA" represents trimellitic anhydride units,

[0544] "MAA" means methacrylic acid units,

[0545] "Solid" means solid particles,

[0546] "Suspended" means that the granular polymer is prepared by suspension polymerization, "dissolved" means that the granular polymer is prepared by dissolution suspension method, "emulsified" means that the granular polymer is prepared by emulsion polymerization, "AA" means acrylic acid unit,

[0547] "Aam" represents acrylamide unit,

[0548] "AMPS" means 2-acrylamido-2-methylpropanesulfonic acid units,

[0549] "CMC" means carboxymethyl cellulose unit,

[0550] “NH 4+ " indicates ammonium salt,

[0551] “Li + " indicates lithium salt,

[0552] “Na + " indicates sodium salt,

[0553] "ACL" means acrylic copolymer,

[0554] "SBR" means styrene-butadiene copolymer,

[0555] "Content" represents the content relative to 100 parts by mass of the particulate polymer, "BIT" represents 1,2-benzo-4-isothiazoline-3-one,

[0556] “Heat-resistant particles” refer to non-conductive heat-resistant particles.

[0557] [Table 1]

[0558]

[0559] As is clear from Table 1, the adhesive compositions of Examples 1 to 21 have excellent long-term redispersibility and can enable the functional layer to exhibit excellent adhesiveness.

[0560] Industrial applicability

[0561] According to the present invention, it is possible to provide a binder composition for a functional layer of an electrochemical device that has excellent redispersibility after long-term storage and can enable the functional layer to exhibit excellent adhesiveness.

[0562] Furthermore, according to the present invention, there can be provided a slurry composition for an electrochemical element functional layer using the binder composition for an electrochemical element functional layer of the present invention.

[0563] Furthermore, according to the present invention, there can be provided a laminate for an electrochemical device having a functional layer formed using the binder composition for an electrochemical device functional layer or the slurry composition for an electrochemical device functional layer.

[0564] Furthermore, according to the present invention, an electrochemical device including the above-mentioned electrochemical device laminate can be provided.

Claims

1. An adhesive composition for an electrochemical element functional layer, comprising a granular polymer, a water-soluble polymer and water, The particulate polymer has a volume particle size D50 of 1.0 μm or more and 15.0 μm or less, and a true specific gravity of 1.00 or more and 2.00 or less.

2. The adhesive composition for an electrochemical element functional layer according to claim 1, wherein The water-soluble polymer has a weight average molecular weight of 80,000 or more and 500,000 or less.

3. The adhesive composition for an electrochemical element functional layer according to claim 1, wherein The water-soluble polymer has a weight average molecular weight of 5,000 or more and 200,000 or less.

4. The adhesive composition for an electrochemical device functional layer according to any one of claims 1 to 3, wherein The water-soluble polymer has an acid group.

5. The adhesive composition for an electrochemical device functional layer according to any one of claims 1 to 4, wherein The pH of the adhesive composition for an electrochemical device functional layer is 6.0 or higher and 12.0 or lower.

6. The adhesive composition for an electrochemical device functional layer according to any one of claims 1 to 5, wherein The viscosity of the adhesive composition for an electrochemical device functional layer is 0.5 mPa·s or more and 10 mPa·s or less.

7. The adhesive composition for an electrochemical device functional layer according to any one of claims 1 to 6, wherein The adhesive composition for the electrochemical element functional layer further comprises a granular adhesive material.

8. The adhesive composition for an electrochemical device functional layer according to any one of claims 1 to 7, wherein The solid content concentration of the adhesive composition for an electrochemical device functional layer is 10.0 mass % or more and 35.0 mass % or less.

9. The adhesive composition for an electrochemical device functional layer according to any one of claims 1 to 8, wherein The adhesive composition for an electrochemical device functional layer further includes an amine compound. 10 . A slurry composition for an electrochemical device functional layer, comprising the binder composition for an electrochemical device functional layer according to claim 1 and non-conductive heat-resistant particles.

11. A laminate for an electrochemical element, comprising a substrate and a functional layer formed on the substrate. The functional layer is formed using the binder composition for an electrochemical device functional layer according to any one of claims 1 to 9 or the slurry composition for an electrochemical device functional layer according to claim 10 . 12 . An electrochemical device comprising the electrochemical device laminate according to claim 11 .

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