Composition for electrochemical element functional layer, functional layer for electrochemical element, laminate for electrochemical element, method for manufacturing laminate for electrochemical element, and electrochemical element

Abstract

The objective of the present invention is to provide a composition for an electrochemical element functional layer that can be used to form an electrochemical element functional layer capable of imparting excellent process adhesiveness and blocking resistance to electrochemical element members such as electrodes and separators. A composition for an electrochemical element functional layer according to the present invention includes a first particulate polymer and a second particulate polymer, and is characterized in that the second particulate polymer has a viscosity between 50 mPa·s and 20,000 mPa·s, inclusive, at pH 9.8.

Description

Composition for electrochemical device functional layer, functional layer for electrochemical device, laminate for electrochemical device, method for manufacturing laminate for electrochemical device, and electrochemical device

[0001] The present invention relates to a composition for a functional layer of an electrochemical device, a functional layer for an electrochemical device, a laminate for an electrochemical device, a method for producing a laminate for an electrochemical device, and an electrochemical device.

[0002] Electrochemical devices such as non-aqueous secondary batteries, such as lithium-ion secondary batteries, and electric double-layer capacitors are small, lightweight, have high energy density, and can be repeatedly charged and discharged, and are therefore used in a wide range of applications.

[0003] For example, non-aqueous secondary batteries such as lithium-ion secondary batteries generally 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. Here, the surfaces of the electrodes and / or separators may be provided with a porous membrane layer to improve heat resistance and strength, or an adhesive layer to improve adhesion between battery components (hereinafter, these may be collectively referred to as "functional layers"). Specifically, an electrode formed by forming a functional layer on an electrode substrate formed by providing an electrode mixture layer on a current collector, or a separator formed by forming a functional layer on a separator substrate, are used as battery components.

[0004] Therefore, in recent years, improvements to functional layers have been actively pursued with the aim of further improving the performance of electrochemical elements such as non-aqueous secondary batteries. Specifically, for example, Patent Document 1 discloses a composition for a functional layer of a non-aqueous secondary battery, which contains a particulate polymer having a core-shell structure with a core portion and a shell portion partially covering the outer surface of the core portion, and in which the glass transition temperatures and electrolyte swelling degrees of the core portion and the shell portion are each within a predetermined range.

[0005] Patent No. 6504158

[0006] In the manufacturing process of electrochemical elements such as lithium-ion secondary batteries, electrochemical element components before immersion in an electrolyte solution are stacked together using a roll press or the like, and then cut to a desired size as needed or transported as a laminate. During the cutting or transport, the stacked electrochemical element components may become misaligned, resulting in defects and reduced productivity. Therefore, electrochemical element components are required to have the ability to bond together electrochemical element components during the manufacturing process of the electrochemical element (process adhesion).

[0007] On the other hand, in the manufacturing process of electrochemical devices such as lithium-ion secondary batteries, it is common to directly wind up electrochemical device components manufactured in a long length and store and transport them. However, when electrochemical device components having functional layers are stored or transported in a wound state, adjacent electrochemical device components may adhere to each other via the functional layer, i.e., blocking may occur, resulting in defects and reduced productivity. Therefore, electrochemical device components having functional layers are required to ensure the above-mentioned process adhesion while also having the ability to suppress blocking during storage, transportation, and the manufacturing process (blocking resistance). However, the above-mentioned conventional nonaqueous secondary battery functional layer compositions have room for improvement in terms of achieving both high levels of process adhesion and blocking resistance.

[0008] Therefore, an object of the present invention is to provide a technology relating to a functional layer for an electrochemical device that can impart excellent process adhesion and blocking resistance to electrochemical device components such as electrodes and separators.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and have found that a composition for an electrochemical device functional layer can be obtained by using a first particulate polymer in combination with a second particulate polymer having predetermined properties, which can form an electrochemical device functional layer that can impart excellent process adhesion and blocking resistance to electrochemical device components, and have completed the present invention.

[0010] That is, the present invention aims to advantageously solve the above-mentioned problems, and the present invention provides [1] a composition for an electrochemical device functional layer comprising a first particulate polymer and a second particulate polymer, wherein the second particulate polymer has a viscosity at pH 9.8 of 50 mPa·s or more and 20,000 mPa·s or less. By incorporating the first particulate polymer and the second particulate polymer, whose viscosity at pH 9.8 is within a predetermined range, into the composition for an electrochemical device functional layer, a composition for an electrochemical device functional layer can be obtained that can form an electrochemical device functional layer that can impart excellent process adhesion and blocking resistance to electrochemical device components. In the present invention, the viscosity of the particulate polymer can be measured by the method described in the examples.

[0011] [2] In the composition for electrochemical device functional layers described in [1], the first particulate polymer preferably has a volume average particle diameter of 1.0 μm or more and 15.0 μm or less, and the second particulate polymer preferably has a volume average particle diameter of 0.05 μm or more and less than 1.0 μm. When the volume average particle diameter of the first particulate polymer is equal to or greater than the lower limit, the electrochemical device component can be imparted with better process adhesiveness. When the volume average particle diameter of the first particulate polymer is equal to or less than the upper limit, the output characteristics of the resulting electrochemical device can be improved. When the volume average particle diameter of the second particulate polymer is equal to or greater than the lower limit, the electrochemical device component can be imparted with better blocking resistance. When the volume average particle diameter of the second particulate polymer is less than the upper limit, the electrochemical device component can be imparted with better process adhesiveness. In the present invention, the volume average particle diameters of the first particulate polymer and the second particulate polymer can be measured by the method described in the Examples.

[0012] [3] In the composition for an electrochemical device functional layer according to [1] or [2], the second particulate polymer preferably contains structural units derived from a monomer having a solubility of 10 g or more in 100 mL of water in a proportion of 5% by mass to 50% by mass. If the second particulate polymer contains structural units derived from a monomer having a solubility of 10 g or more in 100 mL of water within the above-mentioned predetermined range, the electrochemical device member can be imparted with even better blocking resistance. In the present invention, the solubility in 100 mL of water is a value measured at 25°C, and can be measured, for example, by the EPA method (EPA Chemical Fate testing Guideline CG-1500 Water Solubility). In the present invention, the "content ratio of monomer units (structural units)" means: １ It can be measured using a nuclear magnetic resonance (NMR) method such as H-NMR.

[0013] [4] In the composition for an electrochemical element functional layer according to any one of [1] to [3], the second particulate polymer preferably contains structural units derived from a monomer having a solubility of less than 10 g in 100 mL of water in a proportion of 50% by mass to 95% by mass. If the second particulate polymer contains structural units derived from a monomer having a solubility of less than 10 g in 100 mL of water within the above-mentioned range, the electrochemical element member can be provided with even better blocking resistance.

[0014] [5] In the composition for an electrochemical element functional layer according to any one of [1] to [4], the second particulate polymer preferably contains structural units derived from a monomer having a solubility of less than 5 g in 100 mL of water in a proportion of 50% by mass to 95% by mass. If the second particulate polymer contains structural units derived from a monomer having a solubility of less than 5 g in 100 mL of water within the above-mentioned range, even better blocking resistance can be imparted to the electrochemical element member.

[0015] [6] In the composition for an electrochemical element functional layer according to any one of [1] to [5], the second particulate polymer preferably contains a crosslinkable monomer unit in a proportion of 0.01% by mass to 30% by mass. If the second particulate polymer contains the crosslinkable monomer unit within the above-mentioned range, the electrochemical element member can be provided with even better blocking resistance.

[0016] [7] In the composition for an electrochemical device functional layer according to any one of [1] to [6], the first particulate polymer preferably has a glass transition temperature of -50°C or higher and 50°C or lower, and the second particulate polymer preferably has a glass transition temperature of 30°C or higher and 120°C or lower. When the glass transition temperature of the first particulate polymer is equal to or higher than the lower limit, the electrochemical device member can be imparted with even better blocking resistance. When the glass transition temperature of the first particulate polymer is equal to or lower than the upper limit, the electrochemical device member can be imparted with even better process adhesion. When the glass transition temperature of the second particulate polymer is equal to or higher than the lower limit, the electrochemical device member can be imparted with even better blocking resistance. When the glass transition temperature of the second particulate polymer is equal to or lower than the upper limit, the electrochemical device member can be imparted with even better process adhesion. In the present invention, the glass transition temperatures of the first particulate polymer and the second particulate polymer can be measured by the method described in the Examples.

[0017] [8] In the composition for an electrochemical device functional layer according to any one of [1] to [7], the second particulate polymer preferably has an electrolyte swelling degree of 100% or more and 600% or less. When the electrolyte swelling degree of the second particulate polymer is within the above-mentioned range, the output characteristics of the resulting electrochemical device can be improved. In the present invention, the electrolyte swelling degree of the second particulate polymer can be measured by the method described in the Examples.

[0018] [9] The composition for an electrochemical device functional layer according to any one of [1] to [8] preferably further contains water and has a pH of 5.0 to 12.0. If the pH of the composition for an electrochemical device functional layer is within the above range, it is possible to impart even better blocking resistance to the electrochemical device member.

[0019] Another object of the present invention is to advantageously solve the above-mentioned problems, and the present invention provides

[10] a functional layer for an electrochemical device, formed using the composition for an electrochemical device functional layer according to any one of [1] to [9] above. By forming an electrochemical device functional layer using the composition for an electrochemical device functional layer described above, it is possible to impart excellent process adhesion and blocking resistance to an electrochemical device member including the functional layer.

[0020] The present invention also aims to advantageously solve the above-mentioned problems, and provides a laminate for electrochemical devices, comprising:

[11] a substrate; and a functional layer for electrochemical devices formed on the substrate, the functional layer for electrochemical devices being the functional layer for electrochemical devices described in

[10] above. The laminate for electrochemical devices comprising the functional layer for electrochemical devices can impart excellent process adhesion and blocking resistance to electrochemical device components.

[0021] The present invention also aims to advantageously solve the above-mentioned problems, and provides a method for producing a laminate for an electrochemical device, comprising the steps of: preparing a composition for an electrochemical device functional layer, the composition comprising a first particulate polymer, a second particulate polymer, and a dispersion medium; and applying the composition for an electrochemical device functional layer to a substrate and drying it, wherein the second particulate polymer has a viscosity of 50 mPa·s or more and 20,000 mPa·s or less at pH 9.8. According to the method for producing a laminate for an electrochemical device, a laminate for an electrochemical device that can impart excellent process adhesion and blocking resistance to electrochemical device components can be easily obtained at low cost.

[0022]

[13] In the method for producing a laminate for electrochemical devices according to

[12] above, the composition for electrochemical device functional layers preferably contains water and has a pH of 5.0 or more and 12.0 or less. By applying a composition for electrochemical device functional layers containing water and having a pH within the above-mentioned range to a substrate, a laminate for electrochemical devices having even better blocking resistance can be obtained.

[0023] Another object of the present invention is to advantageously solve the above-mentioned problems, and the present invention provides

[14] an electrochemical device comprising the laminate for electrochemical devices described in

[11] above. The electrochemical device comprising the laminate for electrochemical devices can exhibit excellent electrochemical characteristics (output characteristics, cycle characteristics).

[0024] According to the present invention, it is possible to provide a composition for an electrochemical device functional layer that can form a functional layer for an electrochemical device that can impart excellent process adhesion and blocking resistance to an electrochemical device member.The present invention also provides a functional layer for an electrochemical device that can impart excellent process adhesion and blocking resistance to an electrochemical device member, and a laminate for an electrochemical device that includes the functional layer for an electrochemical device.The present invention also provides a method for producing the laminate for an electrochemical device, and an electrochemical device that includes the laminate for an electrochemical device.

[0025] Hereinafter, embodiments of the present invention will be described in detail. Here, the composition for an electrochemical device functional layer of the present invention is suitably used, for example, as a material for producing the functional layer for an electrochemical device of the present invention. The functional layer for an electrochemical device of the present invention is produced using the composition for an electrochemical device functional layer of the present invention and can be suitably used, for example, as a part of an electrochemical device member. The laminate for an electrochemical device of the present invention is produced using the composition for an electrochemical device functional layer of the present invention and can be used, for example, as an electrochemical device member. The method for producing a laminate for an electrochemical device of the present invention can be suitably used, for example, to produce the laminate for an electrochemical device of the present invention. The electrochemical device of the present invention comprises at least the laminate for an electrochemical device of the present invention as an electrochemical device member.

[0026] (Composition for Electrochemical Device Functional Layer) The composition for electrochemical device functional layer of the present invention (hereinafter also simply referred to as "functional layer composition") is characterized in that it contains a first particulate polymer and a second particulate polymer, and the viscosity of the second particulate polymer at pH 9.8 is 50 mPa s or more and 20,000 mPa s or less. Therefore, the composition for functional layer of the present invention can impart excellent process adhesion and blocking resistance to electrochemical device components such as electrodes and separators having a functional layer formed using the functional layer composition.

[0027] Although the mechanism is not entirely clear, it is presumed to be as follows. Specifically, the process adhesiveness of the electrochemical element members is believed to be exhibited by the first particulate polymer acting as an adhesive to adhere the electrochemical element members when the electrochemical element members are laminated by, for example, a flat plate press. Here, the second particulate polymer, whose viscosity at pH 9.8 is within a predetermined range, is believed to be well positioned on the surface of the first particulate polymer in the functional layer, thereby suppressing the adhesiveness of the first particulate polymer. Therefore, it is presumed that, when the coating film of the electrochemical element member is peeled off, the second particulate polymer suppresses adhesion between the electrochemical element members due to the adhesiveness of the first particulate polymer, thereby exhibiting excellent blocking resistance.

[0028] The first particulate polymer contained in the functional layer composition of the present invention is a component that can function as an adhesive that exhibits adhesiveness when laminating electrochemical element components having functional layers formed using the functional layer composition. Note that the viscosity of the first particulate polymer at pH 9.8 described below is usually outside the range of 50 mPa s to 20,000 mPa s.

[0029] <<Volume average particle diameter>> From the viewpoint of further improving process adhesiveness, the volume average particle diameter of the first particulate polymer is preferably larger than the volume average particle diameter of the second particulate polymer, more preferably 1.0 μm or more, even more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and particularly preferably 6.0 μm or more. On the other hand, from the viewpoint of improving the output characteristics of the obtained electrochemical device, the volume average particle diameter of the first particulate polymer is preferably 15.0 μm or less, more preferably 14.0 μm or less, and even more preferably 12.0 μm or less.

[0030] <<Glass Transition Temperature>> From the viewpoint of suppressing an excessive increase in adhesiveness and further improving blocking resistance, the glass transition temperature of the first particulate polymer is preferably −50° C. or higher, more preferably −45° C. or higher, even more preferably −30° C. or higher, and particularly preferably −25° C. or higher. On the other hand, from the viewpoint of further improving process adhesiveness, the glass transition temperature of the first particulate polymer is preferably lower than the glass transition temperature of the second particulate polymer, and is preferably 50° C. or lower, more preferably 40° C. or lower, and even more preferably 20° C. or lower.

[0031] <<Composition>> The composition of the first particulate polymer contained in the functional layer composition of the present invention is not particularly limited as long as the desired effects of the present invention can be obtained. Therefore, as the first particulate polymer, for example, a known polymer that can be used as a particulate polymer when producing a functional layer for an electrochemical device can be used.

[0032] Examples of monomer units (structural units) constituting the first particulate polymer include aromatic vinyl monomer units, (meth)acrylic acid ester monomer units, and crosslinkable monomer units. The first particulate polymer may contain one of these monomer units alone, or two or more of them in any ratio. Specifically, the first particulate polymer preferably contains one or more monomer units selected from the group consisting of aromatic vinyl monomer units, (meth)acrylic acid ester monomer units, and crosslinkable monomer units, more preferably aromatic vinyl monomer units, (meth)acrylic acid ester monomer units, and crosslinkable monomer units, and even more preferably aromatic vinyl monomer units, (meth)acrylic acid ester monomer units, and crosslinkable monomer units. In the present invention, the phrase "containing a monomer unit (structural unit)" means that "a polymer obtained using that monomer contains a structural unit derived from that monomer."

[0033] [Aromatic vinyl monomer unit] Examples of aromatic vinyl monomers that can form aromatic vinyl monomer units include, but are not limited to, styrene, α-methylstyrene, styrene sulfonic acid, butoxystyrene, vinylnaphthalene, etc. Among these, styrene is preferred. These aromatic vinyl monomers may be used alone or in combination of two or more at any ratio.

[0034] The content of the aromatic vinyl monomer units in the first particulate polymer is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20.6% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, when the total amount of all monomer units in the first particulate polymer is taken as 100% by mass. If the content of the aromatic vinyl monomer units is above the lower limit, the elasticity of the particulate polymer is improved, the strength of the resulting functional layer is ensured, and the adhesion of the functional layer to the substrate can be improved. On the other hand, if the content of the aromatic vinyl monomer units is below the upper limit, the flexibility of the first particulate polymer is increased, and the adhesion of the functional layer to the substrate can be improved.

[0035] [(Meth)acrylic acid ester monomer unit] Examples of (meth)acrylic acid ester monomers that can form the (meth)acrylic acid ester monomer unit include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylates such as n-butyl acrylate and t-butyl acrylate, octyl acrylates such as pentyl acrylate, hexyl acrylate, heptyl acrylate and 2-ethylhexyl acrylate, acrylic acid esters such as nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate and stearyl acrylate. alkyl esters; and methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylates such as n-butyl methacrylate and t-butyl methacrylate, octyl methacrylates such as pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, and 2-ethylhexyl methacrylate, and methacrylic acid alkyl esters such as nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate. Among these, 2-ethylhexyl acrylate is preferred. These (meth)acrylic acid ester monomers may be used alone or in combination of two or more in any ratio. In the present invention, "(meth)acrylic" refers to acrylic and / or methacrylic.

[0036] The content of the (meth)acrylic acid ester monomer units in the first particulate polymer is preferably 50% 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, and even more preferably 68.9% by mass or less, when the total repeating units of the first particulate polymer are taken as 100% by mass. If the content of the (meth)acrylic acid ester monomer units is equal to or less than the upper limit, the blocking resistance of the electrochemical element member having the obtained functional layer can be further improved. On the other hand, if the content of the (meth)acrylic acid ester monomer units is equal to or greater than the lower limit, the adhesion between the functional layer and the substrate can be improved.

[0037] [Crosslinkable Monomer Unit] A crosslinkable monomer unit is a monomer unit that can form a crosslinked structure during or after polymerization by heating or irradiation with energy rays. Examples of monomers that can form crosslinkable monomer units include polyfunctional monomers having two or more polymerization reactive groups in the monomer. Examples of such polyfunctional monomers include divinyl compounds such as allyl methacrylate and divinylbenzene; di(meth)acrylic acid ester compounds such as diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butylene glycol diacrylate; tri(meth)acrylic acid ester compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; and ethylenically unsaturated monomers containing epoxy groups such as allyl glycidyl ether and glycidyl methacrylate. Among these, ethylene glycol dimethacrylate and glycidyl methacrylate are preferred. These crosslinkable monomers may be used singly or in combination of two or more in any ratio. Among them, it is preferable to use two types of these crosslinkable monomers in combination, and it is more preferable to use ethylene glycol dimethacrylate and glycidyl methacrylate in combination.

[0038] The content of the crosslinkable monomer units in the first particulate polymer is preferably 5% by mass or more, more preferably 15% by mass or more, and preferably 20% by mass or less, more preferably 18% by mass or less, when the total repeating units of the first particulate polymer are taken as 100% by mass. If the content of the crosslinkable monomer units is equal to or less than the upper limit, the blocking resistance of the electrochemical element member having the obtained functional layer can be further improved. On the other hand, if the content of the crosslinkable monomer units is equal to or greater than the lower limit, the adhesion between the functional layer and the substrate can be improved.

[0039] -Other Monomer Units- The first particulate polymer may further contain other monomer units. Other monomers capable of forming the other monomer units that can be contained in the first particulate polymer are not particularly limited, and examples thereof include nitrile group-containing monomers, amide group-containing monomers, and carboxyl group-containing monomers. Examples of nitrile group-containing monomers include α,β-ethylenically unsaturated compounds having a nitrile group, such as acrylonitrile; α-halogenoacrylonitriles such as α-chloroacrylonitrile and α-bromoacrylonitrile; and α-alkylacrylonitriles such as methacrylonitrile and α-ethylacrylonitrile. Examples of amide group-containing monomers include acrylamide and methacrylamide. Examples of carboxyl group-containing monomers include acrylic acid, methacrylic acid, maleic acid, and itaconic acid. These other monomers may be used singly or in combination of two or more at any ratio. The content ratio of the other monomer units in the first particulate polymer is not particularly limited, and can be 0% by mass or more and 10% by mass or less, when the total repeating units of the first particulate polymer are 100% by mass.

[0040] <<Preparation of First Particulate Polymer>> The first particulate polymer can be prepared by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent such as water. Here, the proportion of each monomer in the monomer composition is usually the same as the proportion of each monomer unit in the particulate polymer.

[0041] The polymerization method is not particularly limited, and any method such as suspension polymerization, emulsion polymerization aggregation, pulverization, or dissolution suspension can be used. Among them, from the viewpoint of efficiently preparing a particulate polymer, suspension polymerization and emulsion polymerization aggregation are preferred, and suspension polymerization is more preferred. Furthermore, any reaction such as radical polymerization or living radical polymerization can be used as the polymerization reaction.

[0042] Here, as an example, a method for preparing the first particulate polymer by suspension polymerization will be described.

[0043] [Preparation of particulate polymer by suspension polymerization method] (1) Preparation of monomer composition First, the monomers constituting the desired particulate polymer and other compounding agents added as needed are mixed to prepare the monomer composition. (2) Formation of droplets Next, the monomer composition is dispersed in water, a polymerization initiator is added, and then droplets of the monomer composition are formed. Here, the method for forming the droplets is not particularly limited, and for example, the droplets can be formed by shearing and stirring an aqueous medium containing the monomer composition using a disperser such as an emulsifying disperser.

[0044] In this case, examples of the polymerization initiator to be used include oil-soluble polymerization initiators such as t-butylperoxy-2-ethylhexanoate, azobisisobutyronitrile, etc. 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.

[0045] From the viewpoint of stabilizing the formed droplets of the monomer composition in water, it is preferable to form the droplets of the monomer composition by adding a dispersion stabilizer to the water. In this case, examples of the dispersion stabilizer that can be used include polyvinyl alcohol, metal hydroxides such as magnesium hydroxide, and sodium dodecylbenzenesulfonate.

[0046] (3) Polymerization After forming droplets of the monomer composition, the water containing the formed droplets is heated to initiate polymerization, thereby forming a particulate polymer in the water. At this time, the polymerization reaction temperature is preferably 50° C. or higher and 95° C. or lower. The polymerization reaction time is preferably 1 hour or higher and 10 hours or lower, preferably 8 hours or lower, and more preferably 6 hours or lower.

[0047] (4) Washing, Filtration, Dehydration, and Drying Steps After the polymerization is completed, the water containing the particulate polymer is washed, filtered, and dried in accordance with a conventional method, thereby obtaining the particulate polymer.

[0048] <Second Particulate Polymer> The second particulate polymer contained in the functional layer composition of the present invention is a component that is located on the surface of the first particulate polymer in the resulting functional layer and can impart blocking resistance to the electrochemical element member.

[0049] <<Viscosity at pH 9.8>> The second particulate polymer needs to have a viscosity at pH 9.8 (hereinafter also referred to as "η9.8") of 50 mPa·s or more and 20,000 mPa·s or less. If the η9.8 of the second particulate polymer is outside the above range, blocking resistance cannot be ensured. If the η9.8 of the second particulate polymer is within the above range, the second particulate polymer is uniformly dispersed and disposed on the surface of the first particulate polymer in the obtained functional layer, resulting in blocking resistance. From the viewpoint of further improving blocking resistance, the η9.8 of the second particulate polymer is preferably 100 mPa·s or more, more preferably 150 mPa·s or more, even more preferably 500 mPa·s or more, even more preferably 1000 mPa·s or more, particularly preferably 1500 mPa·s or more, and preferably 18000 mPa·s or less, more preferably 16500 mPa·s or less. The η9.8 of the second particulate polymer can be adjusted, for example, by controlling the type and / or content ratio of the monomer units (structural units) constituting the second particulate polymer, the volume average particle diameter of the second particulate polymer, etc.

[0050] <<Volume Average Particle Diameter>> From the viewpoint of further improving blocking resistance, the second particulate polymer preferably has a volume average particle diameter of 0.05 μm or more, more preferably 0.06 μm or more, even more preferably 0.07 μm or more, and even more preferably 0.25 μm or more. On the other hand, from the viewpoint of further improving process adhesiveness, the second particulate polymer preferably has a volume average particle diameter smaller than that of the first particulate polymer, more preferably less than 1.0 μm, even more preferably 0.8 μm or less, and even more preferably 0.6 μm or less.

[0051] <<Glass Transition Temperature>> From the viewpoint of further improving blocking resistance, the second particulate polymer preferably has a glass transition temperature of 30° C. or higher, more preferably 40° C. or higher, even more preferably 50° C. or higher, and even more preferably 80° C. or higher. On the other hand, from the viewpoint of further improving process adhesiveness, the second particulate polymer preferably has a glass transition temperature of 120° C. or lower, more preferably 110° C. or lower, and even more preferably 100° C. or lower.

[0052] <<Electrolyte Swelling Degree>> From the viewpoint of improving the output characteristics of the obtained electrochemical device, the second particulate polymer preferably has an electrolyte swelling degree of 100% or more, more preferably 110% or more, even more preferably 150% or more, even more preferably 300% or more, and preferably 600% or less, more preferably 500% or less, and even more preferably 400% or less. The electrolyte swelling degree of the second particulate polymer can be adjusted, for example, by controlling the type and / or content ratio of the monomer units constituting the second particulate polymer.

[0053] <<Composition>> The second particulate polymer is not particularly limited as long as it is a polymer in particulate form and has a viscosity at pH 9.8 of 50 mPa·s or more and 20,000 mPa·s or less.

[0054] The structural unit of the second particulate polymer can be, for example, a structural unit derived from a monomer having a solubility of 10 g or more in 100 mL of water, or a structural unit derived from a monomer having a solubility of less than 10 g in 100 mL of water.From the viewpoint of further improving blocking resistance, the second particulate polymer preferably comprises a structural unit derived from a monomer having a solubility of 10 g or more in 100 mL of water, more preferably comprises a structural unit derived from a monomer having a solubility of 10 g or more in 100 mL of water and a structural unit derived from a monomer having a solubility of less than 10 g in 100 mL of water, even more preferably comprises a structural unit derived from a monomer having a solubility of 10 g or more in 100 mL of water and a structural unit derived from a monomer having a solubility of less than 5 g in 100 mL of water, and even more preferably comprises a structural unit derived from a monomer having a solubility of 10 g or more in 100 mL of water and a structural unit derived from a monomer having a solubility of less than 5 g in 100 mL of water.

[0055] The second particulate polymer is preferably an acrylic polymer and / or a conjugated diene polymer. Here, the acrylic polymer refers to a polymer containing a (meth)acrylic acid ester monomer unit, which will be described later. The conjugated diene polymer refers to a polymer containing a conjugated diene monomer unit, which will be described later. Specific examples of the conjugated diene polymer include copolymers containing aromatic vinyl monomer units and aliphatic conjugated diene monomer units, such as styrene-butadiene copolymer (SBR), butadiene rubber (BR), acrylic rubber (NBR) (a copolymer containing acrylonitrile units and butadiene units), and hydrogenated products thereof. As the conjugated diene polymer, styrene-butadiene copolymer (SBR) and acrylic rubber (NBR) are preferred.

[0056] [Structural Unit Derived from a Monomer Having a Solubility of 10 g or More in 100 mL of Water] The structural unit derived from a monomer having a solubility of 10 g or more in 100 mL of water is not particularly limited, and examples thereof include acid group-containing monomer units.

[0057] Examples of acid group-containing monomers capable of forming acid group-containing monomer units include monomers having a carboxylic acid group, monomers having a sulfonic acid group, monomers having a phosphoric acid group, and monomers having a hydroxyl group. From the viewpoint of further improving blocking resistance, monomers having a carboxylic acid group and monomers having a sulfonic acid group are preferred, and monomers having a carboxylic acid group are more preferred.

[0058] Examples of monomers having a carboxylic acid group include monocarboxylic acids and dicarboxylic acids. Examples of monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Among these, methacrylic acid is preferred. Examples of monomers having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, (meth)acrylic acid-2-ethyl sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid. Among these, vinyl sulfonic acid is preferred. In this specification, "(meth)allyl" means allyl and / or methallyl. Examples of monomers having a phosphate group include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate. In this specification, "(meth)acryloyl" means acryloyl and / or methacryloyl. Examples of monomers having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate. These acid group-containing monomers may be used alone or in combination of two or more in any ratio.

[0059] [Structural Unit Derived from a Monomer Having a Solubility of Less than 10 g in 100 mL of Water] The "monomer having a solubility of less than 10 g in 100 mL of water" that can form the "structural unit derived from a monomer having a solubility of less than 10 g in 100 mL of water" is not particularly limited, and examples thereof include monomers (compounds) having a solubility of less than 5 g in 100 mL of water, such as aromatic vinyl monomers, (meth)acrylic acid ester monomers (excluding methyl acrylate), nitrile group-containing monomers (excluding acrylonitrile), crosslinkable monomers, and aliphatic conjugated diene monomers, as well as monomers (compounds) having a solubility of 5 g or more but less than 10 g in 100 mL of water, such as methyl acrylate and acrylonitrile.

[0060] As the aromatic vinyl monomer capable of forming the aromatic vinyl monomer unit, those mentioned in the section "First Particulate Polymer" can be used alone or in combination of two or more. Among them, it is preferable to use styrene.

[0061] As the (meth)acrylic acid ester monomer capable of forming the (meth)acrylic acid ester monomer unit, those mentioned in the section "First Particulate Polymer" can be used alone or in combination of two or more. Among them, butyl acrylate is preferably used.

[0062] As the crosslinkable monomer capable of forming the crosslinkable monomer unit, those mentioned in the section "First Particulate Polymer" can be used alone or in combination of two or more. Among them, ethylene glycol dimethacrylate is preferably used.

[0063] As examples of the nitrile group-containing monomer capable of forming the nitrile group-containing monomer unit, those mentioned in the section "First Particulate Polymer" can be used alone or in combination of two or more. Among them, it is preferable to use acrylonitrile.

[0064] Examples of the aliphatic conjugated diene monomer capable of forming the aliphatic conjugated diene monomer unit include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, etc. Among these, 1,3-butadiene is preferred.

[0065] [Content of each monomer unit (structural unit)] -Structural unit derived from a monomer having a solubility of 10 g or more in 100 mL of water- From the viewpoint of further improving blocking resistance, the content of "structural units derived from a monomer having a solubility of 10 g or more in 100 mL of water" in the second particulate polymer is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 22% by mass or more, even more preferably 25% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 38% by mass or less, when the total monomer units (structural units) in the second particulate polymer is taken as 100% by mass.

[0066] --Acid Group-Containing Monomer Unit-- From the viewpoint of further improving blocking resistance, the content of the "acid group-containing monomer unit" in the second particulate polymer is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and even more preferably 25% by mass or more, and is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, when all monomer units (structural units) in the second particulate polymer are taken as 100% by mass.

[0067] -Structural units derived from monomers having a solubility of less than 10 g in 100 mL of water- In terms of further improving blocking resistance, the content of "structural units derived from monomers having a solubility of less than 10 g in 100 mL of water" in the second particulate polymer (the sum of the content of structural units derived from monomers having a solubility of 5 g or more but less than 10 g in 100 mL of water and the content of structural units derived from monomers having a solubility of less than 5 g in 100 mL of water) is preferably 50% by mass or more, more preferably 55% by mass or more, and even more preferably 60% by mass or more, and is preferably 95% by mass or less, more preferably 88% by mass or less, even more preferably 80% by mass or less, and even more preferably 75% by mass or less, when all monomer units (structural units) in the second particulate polymer are taken as 100% by mass.

[0068] -Structural units derived from monomers having a solubility of less than 5 g in 100 mL of water- When the second particulate polymer contains only "structural units derived from monomers having a solubility of less than 5 g in 100 mL of water" as "structural units derived from monomers having a solubility of less than 10 g in 100 mL of water," the content of "structural units derived from monomers having a solubility of less than 5 g in 100 mL of water" in the second particulate polymer is, from the viewpoint of further improving blocking resistance, preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 65% ​​by mass or more, and preferably 95% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, and even more preferably 75% by mass or less, when the total monomer units (structural units) in the second particulate polymer is taken as 100% by mass.

[0069] -Structural units derived from monomers having a solubility of 5 g or more and less than 10 g in 100 mL of water- When the second particulate polymer contains only "structural units derived from monomers having a solubility of 5 g or more and less than 10 g in 100 mL of water" as "structural units derived from monomers having a solubility of 5 g or more and less than 10 g in 100 mL of water," the "structural units derived from monomers having a solubility of 5 g or more and less than 10 g in 100 mL of water" is preferably 1% by mass or more, more preferably 2% by mass or more, and preferably 15% by mass or less, more preferably 7% by mass or less, when the total monomer units (structural units) in the second particulate polymer is taken as 100% by mass.

[0070] Here, when the second particulate polymer contains, as the "structural units derived from a monomer having a solubility of less than 10 g in 100 mL of water", "structural units derived from a monomer having a solubility of less than 5 g in 100 mL of water" and "structural units derived from a monomer having a solubility of 5 g or more and less than 10 g in 100 mL of water", the "structural units derived from a monomer having a solubility of less than 5 g in 100 mL of water" should account for 49% by mass or more when the total amount of all monomer units (structural units) in the second particulate polymer is taken as 100% by mass. The content of "structural units derived from monomers having a solubility of 5 g or more and less than 10 g in 100 mL of water" is preferably 1% by mass or more, more preferably 2% by mass or more, and preferably 7% by mass or less, more preferably 5% by mass or less, and is preferably 88% by mass or less, more preferably 83% by mass or less, when the total monomer units (structural units) in the second particulate polymer is taken as 100% by mass.

[0071] --Aromatic vinyl monomer unit-- From the viewpoint of further improving blocking resistance, the content of "aromatic vinyl monomer unit" in the second particulate polymer is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, and even more preferably 50% by mass or more, when all monomer units (structural units) in the second particulate polymer are taken as 100% by mass. Also, it is preferably 65% ​​by mass or less, and more preferably 60% by mass or less.

[0072] --(Meth)acrylic acid ester monomer unit-- From the viewpoint of further improving blocking resistance, the content of "(meth)acrylic acid ester monomer unit" in the acrylic polymer is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 24% by mass or more, when all monomer units (structural units) in the acrylic polymer are taken as 100% by mass, and is preferably 40% by mass or less, and more preferably 35% by mass or less.

[0073] --Nitrile Group-Containing Monomer Unit-- From the viewpoint of further improving blocking resistance, the content of "nitrile group-containing monomer units" in the conjugated diene polymer is preferably 15% by mass or more, and more preferably 20% by mass or more, and is preferably 40% by mass or less, and more preferably 35% by mass or less, when all monomer units (structural units) in the conjugated diene polymer are taken as 100% by mass.

[0074] --Crosslinkable Monomer Unit-- From the viewpoint of further improving blocking resistance, the content of the "crosslinkable monomer unit" in the second particulate polymer is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, when all monomer units (structural units) in the second particulate polymer are taken as 100% by mass. Also, it is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0075] --Aliphatic conjugated diene monomer units-- From the viewpoint of further improving blocking resistance, the content of "aliphatic conjugated diene monomer units" in the conjugated diene polymer is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, and is preferably 40% by mass or less, and more preferably 35% by mass or less, when all monomer units (structural units) in the conjugated diene polymer are taken as 100% by mass. Note that in the present invention, aliphatic conjugated diene monomer units are not included in crosslinkable monomer units.

[0076] <<Preparation of Second Particulate Polymer>> The second particulate polymer is not particularly limited, and can be prepared in the same manner as the above-mentioned first particulate polymer.

[0077] <<Mass Ratio of First Particulate Polymer to Second Particulate Polymer>> From the viewpoint of further improving blocking resistance, the mass ratio of the first particulate polymer to the second particulate polymer (first particulate polymer / second particulate polymer) is preferably 5 or more, more preferably 10 or more, and is preferably 50 or less, more preferably 40 or less.

[0078] <<Forms of Presence of First Particulate Polymer and Second Particulate Polymer>> In a composition for a functional layer containing a dispersion medium, etc., the first particulate polymer and the second particulate polymer usually exist as separate entities separated from each other. That is, the first particulate polymer and the second particulate polymer in the composition for a functional layer usually differ from polymers having a core-shell structure in which shell particles are attached to at least a part of the surface of a core particle.

[0079] <Other Components> The composition for a functional layer of the present invention may further contain other components in addition to the first particulate polymer and the second particulate polymer described above. Examples of other components include a binder, a dispersion medium, non-conductive heat-resistant particles, and other additives.

[0080] <<Binder>> The binder optionally contained in the functional layer composition is used to prevent components such as the first particulate polymer and the second particulate polymer from falling off from the functional layer. The binder is a component whose composition and properties are different from those of the first particulate polymer and the second particulate polymer. Specifically, the binder differs from those of the first particulate polymer and the second particulate polymer, for example, in at least one of the composition, volume average particle size, and glass transition temperature.

[0081] [Binder Composition] The binder composition is not particularly limited and may be, for example, a known polymer that is water-insoluble and dispersible in a dispersion medium such as water. Among these, conjugated diene polymers and acrylic polymers are preferred, and acrylic polymers are more preferred. In the present invention, a polymer being "water-insoluble" means that when 0.5 g of the polymer is dissolved in 100 g of water at 25°C, the insoluble content is 90 mass% or more.

[0082] Specific examples of conjugated diene polymers include, but are not limited to, copolymers containing aromatic vinyl monomer units and aliphatic conjugated diene monomer units, such as styrene-butadiene copolymer (SBR), butadiene rubber (BR), acrylic rubber (NBR) (copolymers containing acrylonitrile units and butadiene units), and hydrogenated versions thereof. These binders may be used alone or in combination of two or more types in any ratio.

[0083] The acrylic polymer that can be preferably used as the binder is not particularly limited, and examples thereof include the above-mentioned polymers containing (meth)acrylic acid ester monomer units, acid group-containing monomer units, nitrile group-containing monomer units, and crosslinkable monomer units.

[0084] [Binder Structure] The structure of the binder in the functional layer composition may be the same as or different from the structure of the binder in the functional layer. For example, the binder structure in the functional layer composition may be particulate or non-particulate. The structure of the binder in the functional layer is not particularly limited, but is usually non-particulate.

[0085] [Volume average particle diameter of binder] When the binder is present in particulate form in the functional layer composition, the volume average particle diameter of the binder is preferably 0.05 μm or more, more preferably 0.1 μm or more, and even more preferably 0.15 μm or more. It is also preferably smaller than the volume average particle diameter of the first particulate polymer and / or the second particulate polymer, more preferably 0.5 μm or less, even more preferably 0.4 μm or less, and even more preferably 0.3 μm or less. If the volume average particle diameter of the binder is equal to or greater than the lower limit, the dispersibility of the binder in the functional layer can be improved. Furthermore, if the volume average particle diameter is equal to or less than the upper limit, the particulate polymer can be more effectively bound in the functional layer. In the present invention, the volume average particle diameter of the binder can be measured by the method described in the examples.

[0086] <<Glass Transition Temperature of Binder>> The glass transition temperature (Tg) of the binder is preferably -100°C or higher, more preferably -90°C or higher, and even more preferably -80°C or higher. It is also preferably lower than the glass transition temperature of the first particulate polymer and / or the second particulate polymer, more preferably 30°C or lower, even more preferably 20°C or lower, and particularly preferably 15°C or lower. If the glass transition temperature of the binder is above the lower limit, the adhesiveness and strength of the binder can be increased. If the glass transition temperature of the binder is 30°C or lower, the particulate polymer can be fixed to the substrate without heating, allowing the functional layer to be well formed on the substrate. In the present invention, the glass transition temperature of the binder can be measured by the method described in the examples.

[0087] <<Binder Content>> The binder content in the functional layer composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.5 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the particulate polymer (the total of the first particulate polymer and the second particulate polymer). If the binder content is equal to or greater than the above-mentioned lower limit, the first particulate polymer and the second particulate polymer can be sufficiently prevented from falling off the functional layer, and the process adhesion of the functional layer can be sufficiently improved. On the other hand, if the binder content is equal to or less than the above-mentioned upper limit, the ionic conductivity of the functional layer can be prevented from decreasing, and the electrochemical characteristics (output characteristics, cycle characteristics) of the electrochemical element can be prevented from decreasing.

[0088] The binder is not particularly limited and can be prepared, for example, 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 usually the same as the ratio of each monomer unit in the binder.

[0089] The polymerization method and polymerization reaction are not particularly limited, and for example, the polymerization methods and polymerization reactions exemplified in the polymerization method for the first particulate polymer described above can be used.

[0090] <<Dispersion Medium>> The dispersion medium that can be optionally contained in the functional layer composition of the present invention is one that can turn the functional layer composition into a slurry (hereinafter, the slurry functional layer composition may be referred to as a "functional layer slurry composition"). Note that the dispersion medium volatilizes during the formation of the functional layer, which includes a drying step of the functional layer slurry composition, as described below. This results in a functional layer made of the solid content (dried product) of the functional layer slurry composition.

[0091] As the dispersion medium, any medium can be used that can be volatilized during the formation of the functional layer, has low dissolving properties for components such as the particulate polymer, and can maintain the dispersion state of the components such as the particulate polymer. An aqueous medium is preferred as the dispersion medium. The aqueous medium is water or a mixture of water and a medium other than water. By using an aqueous medium as the dispersion medium, the environmental load can be reduced and the handling of the slurry composition for the functional layer can be made easier. Of these, it is preferred to use water as the dispersion medium.

[0092] Examples of aqueous media that can be used in combination with water include cyclic aliphatic hydrocarbon compounds such as cyclopentane and cyclohexane; aromatic hydrocarbon compounds such as toluene and xylene; ketone compounds such as ethyl methyl ketone and cyclohexanone; ester compounds such as ethyl acetate, butyl acetate, γ-butyrolactone, and ε-caprolactone; nitrile compounds such as acetonitrile and propionitrile; ether compounds such as tetrahydrofuran and ethylene glycol diethyl ether; alcohol compounds such as methanol, ethanol, isopropanol, ethylene glycol, and ethylene glycol monomethyl ether; and amide compounds such as N-methylpyrrolidone (NMP) and N,N-dimethylformamide. These may be used alone, or two or more may be used in any combination at any ratio. The amount of the medium other than water is preferably 5 parts by mass or less per 100 parts by mass of water.

[0093] The amount of dispersion medium in the functional layer slurry composition is preferably set so that the solid content concentration of the functional layer slurry composition falls within a desired range.The specific solid content concentration of the functional layer slurry composition is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, particularly preferably 65% ​​by mass or less.By making the solid content concentration within the above range, the functional layer slurry composition can be made to have properties suitable for the application and drying process.

[0094] <<Non-conductive heat-resistant particles>> The non-conductive heat-resistant particles that may be optionally contained in the functional layer composition of the present invention are materials that can impart heat resistance to the resulting functional layer. If the functional layer composition contains non-conductive heat-resistant particles, the resulting functional layer can combine the process adhesion provided by the first particulate polymer, the blocking resistance provided by the second particulate polymer, and the heat resistance provided by the non-conductive heat-resistant particles, which is preferable. The non-conductive heat-resistant particles can be inorganic particles and / or organic particles. In particular, it is preferable that the non-conductive heat-resistant particles include inorganic particles. If the functional layer composition contains inorganic particles, the heat resistance of the resulting functional layer can be further improved.

[0095] It is preferable that the inorganic particle material is stable in the environment in which the electrochemical element is used and is electrochemically stable. From this viewpoint, preferred inorganic particle materials include aluminum oxide (alumina), aluminum oxide hydrate (boehmite (AlOOH)), gibbsite (Al(OH ３ )), silicon oxide, magnesium hydroxide (magnesia), magnesium hydroxide, calcium oxide, titanium oxide (titania), barium titanate (BaTiO ３Examples of inorganic particles include oxide particles such as ZrO and alumina-silica composite oxide; nitride particles such as aluminum nitride and boron nitride; covalently bonded crystalline particles such as silicon and diamond; sparingly soluble ionic crystalline particles such as barium sulfate, calcium fluoride and barium fluoride; and clay fine particles such as talc, montmorillonite, kaolin and calcined kaolin. Among these, alumina is preferred as the material for the inorganic particles. Furthermore, these inorganic particles may be subjected to element substitution, surface treatment, solid solution formation, etc. as necessary. Note that these inorganic particles may be used alone or in combination of two or more types in any ratio.

[0096] The organic particle material is preferably electrochemically stable and stable in the environment in which the electrochemical device is used. From this perspective, preferred materials for the organic particles include those containing polyfunctional ethylenically unsaturated monomer units. As the polyfunctional ethylenically unsaturated monomer capable of forming the polyfunctional ethylenically unsaturated monomer unit, a monomer having two or more ethylenically unsaturated bonds per molecule (excluding conjugated diene monomers such as 1,3-butadiene) can be used. Examples of the polyfunctional ethylenically unsaturated monomer include polyfunctional (meth)acrylic acid ester monomers such as allyl (meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate; polyfunctional aromatic vinyl monomers such as divinylbenzene and diisopropenylbenzene; dipropylene glycol diallyl ether, polyglycol diallyl ether, triethylene glycol divinyl ether, hydroquinone diallyl ether, tetraallyloxyethane, trimethylolpropane diallyl ether, allyl or vinyl ethers of polyfunctional alcohols other than those mentioned above, triallylamine, and methylenebisacrylamide. Among these, from the viewpoint of further improving the heat shrinkage resistance of the functional layer, polyfunctional (meth)acrylic acid ester monomers and polyfunctional aromatic vinyl monomers are preferred, polyfunctional (meth)acrylic acid ester monomers are more preferred, and ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate are even more preferred. The content of polyfunctional monomer units in the organic particles is preferably 50% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, based on 100% by mass of all repeating units of the polymer constituting the organic particles, and is preferably 90% by mass or less, more preferably 85% by mass or less, and even more preferably 83% by mass or less. These organic particles may be used alone, or two or more types may be used in combination at any ratio. Furthermore, organic particles and inorganic particles may be used in combination at any ratio.From the viewpoint of imparting heat resistance, the glass transition temperature (Tg) of the organic particles is preferably higher than 200° C. The glass transition temperature of the organic particles can be measured by differential scanning calorimetry (DSC) described in the examples, similarly to the glass transition temperatures of the particulate polymer and the binder described above.

[0097] [Mass ratio of non-conductive heat-resistant particles to particulate polymer] The mass ratio (non-conductive heat-resistant particles / particulate polymer) of the non-conductive heat-resistant particles to the particulate polymer (first particulate polymer and second particulate polymer) in the functional layer composition is preferably 50 / 50 or more, more preferably 60 / 40 or more, even more preferably 75 / 25 or more, and preferably 97 / 3 or less, more preferably 95 / 5 or less, and even more preferably 93 / 7 or less. If the mass ratio of the non-conductive heat-resistant particles to the particulate polymer in the functional layer composition is above the lower limit, the heat resistance of the functional layer produced can be improved. On the other hand, if the mass ratio of the non-conductive heat-resistant particles to the particulate polymer in the functional layer composition is below the upper limit, the process adhesion of the functional layer produced can be further improved.

[0098] <<Other Additives>> Other additives that may be optionally contained in the functional layer composition include thickeners and dispersants. Examples of thickeners that can be used include carboxymethyl cellulose. Examples of dispersants that can be used include sodium dodecylbenzenesulfonate. The amounts of these additives used in the functional layer composition can be appropriately set within a range that achieves the desired effects of the present invention.

[0099] <pH of Functional Layer Composition> When the functional layer composition contains water as a dispersion medium, the pH of the functional layer composition is preferably 5.0 or higher, more preferably 6.0 or higher, and is preferably 12.0 or lower, more preferably 11.0 or lower. If the pH of the electrochemical element functional layer composition is within the above range, it is possible to impart even better blocking resistance to the electrochemical element member.

[0100] <Preparation of Functional Layer Composition> The method for preparing the functional layer composition of the present invention is not particularly limited. Typically, a functional layer slurry composition is prepared by mixing a first particulate polymer, a second particulate polymer, a dispersion medium, and optional components (at least one selected from the group consisting of binders, non-conductive heat-resistant particles, and other additives) as needed. While the mixing method is not particularly limited, mixing is typically performed using a disperser to efficiently disperse the components. Dispersers capable of uniformly dispersing and mixing the above components are preferred. Examples include ball mills, sand mills, pigment dispersers, crushers, ultrasonic dispersers, homogenizers, and planetary mixers. High-dispersion devices such as bead mills, roll mills, and Filmix are also suitable for achieving high dispersion shear. The pH of the functional layer composition of the present invention is not particularly limited and can be appropriately adjusted by adding a base such as aqueous sodium hydroxide solution or an acid such as hydrochloric acid.

[0101] (Laminate for electrochemical device) A functional layer for an electrochemical device (hereinafter also simply referred to as "functional layer") can be obtained by forming the functional layer composition of the present invention on a suitable substrate. By forming the functional layer on the substrate in this manner, a laminate for an electrochemical device (hereinafter also simply referred to as "laminate") of the present invention can be obtained. The functional layer formed on the substrate can impart excellent process adhesion and blocking resistance to the electrochemical device member. Furthermore, the laminate may further include one or more other layers on the substrate other than the functional layer described above that exhibit the desired function.

[0102] <Functional layer for electrochemical device> The functional layer contains a first particulate polymer and a second particulate polymer, and optionally contains other components (at least one selected from the group consisting of a binder, non-conductive heat-resistant particles, and other additives). Note that the first particulate polymer, the second particulate polymer, and other components may be those described above in the section "Composition for electrochemical device functional layer."

[0103] The first particulate polymer and the second particulate polymer contained in the functional layer are not particularly limited as long as they are particulate, and after bonding the electrochemical element components together via the functional layer, the first particulate polymer and the second particulate polymer may be in a particle shape or any other shape.

[0104] The thickness of the functional layer is preferably 0.01 μm or more, more preferably 0.1 μm or more, even more preferably 0.5 μm or more, and is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 6 μm or less. When the thickness of the functional layer is at least the lower limit of the above range, the strength of the functional layer can be sufficiently ensured, and when the thickness is at most the upper limit of the above range, the ion diffusibility of the functional layer can be ensured, and the electrochemical characteristics (output characteristics, cycle characteristics) of the electrochemical element can be further improved.

[0105] The functional layer is not particularly limited and may be used as an adhesive layer that does not contain non-conductive heat-resistant particles, or as an adhesive layer that contains non-conductive heat-resistant particles. The inclusion of non-conductive heat-resistant particles can impart heat resistance to the functional layer, allowing the functional layer to function as both an adhesive layer and a heat-resistant layer in one layer. Here, when the functional layer contains non-conductive heat-resistant particles, the area in the functional layer where the non-conductive heat-resistant particles are present is referred to as the non-conductive heat-resistant particle layer. That is, for example, when non-conductive heat-resistant particles are present only partially in the thickness direction of the functional layer (e.g., when the particle diameter of the particulate polymer contained in the functional layer is larger than the area where the non-conductive heat-resistant particles are present), the thickness of the non-conductive heat-resistant particle layer will be smaller than the thickness of the functional layer. On the other hand, when non-conductive heat-resistant particles are present throughout the entire thickness of the functional layer, the thickness of the functional layer and the thickness of the non-conductive heat-resistant particle layer will be equal.

[0106] The thickness of the non-conductive heat-resistant particle layer is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1 μm or more, and preferably 6 μm or less, more preferably 5 μm or less, and even more preferably 4 μm or less. When the thickness of the non-conductive heat-resistant particle layer is equal to or greater than the above-mentioned lower limit, the heat resistance of the functional layer can be improved. On the other hand, when the thickness of the non-conductive heat-resistant particle layer is equal to or less than the above-mentioned upper limit, a decrease in the energy density of an electrochemical device including a functional layer can be suppressed. Furthermore, when the thickness of the non-conductive heat-resistant particle layer is equal to or less than the above-mentioned upper limit, the process adhesion of the functional layer can be improved. The thickness of the non-conductive heat-resistant particle layer can be measured, for example, from SEM images obtained by observing the cross section of the laminate using a field emission scanning electron microscope (FE-SEM). Here, the thickness of the non-conductive heat-resistant particle layer is defined as the distance from the surface of the substrate on which the functional layer is formed to the non-conductive heat-resistant particle furthest in the vertical direction. The thickness of the non-conductive heat-resistant particle layer can be adjusted, for example, by the content ratio of the non-conductive heat-resistant particles in the functional layer composition used in the method for forming a laminate for electrochemical devices described below, and the thickness of the coating film to be formed.

[0107] <<Volume average particle diameter of particulate polymer>> Here, the first particulate polymer in the functional layer preferably has a volume average particle diameter of 1.0 μm or more, more preferably 1.5 μm or more, and even more preferably 2.0 μm or more, and preferably 15.0 μm or less, more preferably 14.0 μm or less, and even more preferably 12.0 μm or less. Furthermore, the second particulate polymer in the functional layer preferably has a volume average particle diameter of 0.08 μm or more, more preferably 0.1 μm or more, and even more preferably 0.12 μm or more, and preferably 0.08 μm or less, more preferably 0.06 μm or less, and even more preferably 0.05 μm or less. The volume average particle diameters of the first particulate polymer and the second polymer in the functional layer can be measured using a scanning electron microscope (SEM).

[0108] <Substrate> The type of substrate on which the functional layer is formed is not particularly limited. For example, when the functional layer is used as a component constituting a part of the separator, a separator substrate can be used as the substrate. Also, when the functional layer is used as a component constituting a part of the electrode, an electrode substrate formed by forming an electrode mixture layer on a current collector can be used as the substrate. Furthermore, the use of the laminate obtained by forming a functional layer on a substrate using a functional layer composition is not particularly limited. For example, the functional layer may be formed on a separator substrate or the like and used as an electrochemical device component such as a separator, or the functional layer may be formed on an electrode substrate and used as an electrode, or the functional layer formed on a release substrate may be peeled from the release substrate and attached to another substrate for use as an electrochemical device component. However, from the viewpoint of omitting the step of peeling the release substrate from the functional layer and improving the manufacturing efficiency of the electrochemical device component, it is preferable to use a separator substrate or an electrode substrate as the substrate and use the laminate as an electrochemical device component as is. The functional layer formed on the separator substrate or electrode substrate contains the above-mentioned first particulate polymer and second particulate polymer, and therefore can impart excellent process adhesion and blocking resistance to the electrochemical element member.

[0109] - Current Collector - A material that is electrically conductive and electrochemically durable is used as the current collector. Specifically, current collectors made of, for example, iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. can be used as the current collector. Among these, copper foil is particularly preferred as the current collector used for the negative electrode. Aluminum foil is particularly preferred as the current collector used for the positive electrode. Note that one type of the above-mentioned material may be used alone, or two or more types may be used in combination in any ratio.

[0110] - Separator substrate - The separator substrate on which the functional layer is formed is not particularly limited, and for example, those described in JP 2012-204303 A can be used. Among these, a microporous film made of a polyolefin resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred because it allows the thickness of the entire separator to be thin, thereby increasing the proportion of electrode active material in the electrochemical device and increasing the capacity per volume.

[0111] -Electrode substrate- The electrode substrates (positive electrode substrate and negative electrode substrate) on which the functional layer is formed are not particularly limited, but examples include electrode substrates in which an electrode mixture layer is formed on a current collector. Here, the current collector, the components in the electrode mixture layer (e.g., electrode active materials (positive electrode active material, negative electrode active material) and electrode mixture layer binders (positive electrode mixture layer binder, negative electrode mixture layer binder)), etc.), and the method for forming the electrode mixture layer on the current collector can be known methods. Specifically, for example, the method described in JP 2013-145763 A can be used.

[0112] -Release Substrate- The release substrate on which the functional layer is formed is not particularly limited, and any known release substrate can be used.

[0113] <Other Layers> The other layers that the laminate may optionally include are not particularly limited. For example, the laminate preferably includes, as the other layer, a heat-resistant layer containing non-conductive heat-resistant particles and a binder between the substrate and the functional layer. This can impart heat resistance to the laminate. The binder used in the heat-resistant layer can be one of those described above in the "Composition for Electrochemical Device Functional Layer" section. Furthermore, the non-conductive heat-resistant particles used in the heat-resistant layer are not particularly limited, and can be one of those described above in the "Composition for Electrochemical Device Functional Layer" section.

[0114] The thickness of the heat-resistant layer is not particularly limited as long as it can provide sufficient heat resistance, but is preferably 0.1 μm or more, more preferably 0.2 μm or more, and preferably 20 μm or less, more preferably 15 μm or less. By maintaining the thickness of the heat-resistant layer within the above range, a decrease in ionic conductivity can be suppressed. The method for manufacturing the heat-resistant layer is not particularly limited. For example, the heat-resistant layer can be formed by applying a slurry for the heat-resistant layer containing non-conductive heat-resistant particles, a binder, and a dispersion medium such as water to a substrate and drying the resulting coating. Alternatively, the heat-resistant layer may be formed on the above-mentioned release substrate, and then peeled from the release material and attached to the substrate. Note that other layers, such as the heat-resistant layer, may be provided on one side of the substrate or on both sides of the substrate.

[0115] (Method for manufacturing a laminate for electrochemical devices) The method for manufacturing a laminate for electrochemical devices of the present invention includes a step of preparing a composition for electrochemical device functional layers containing a first particulate polymer, a second particulate polymer, and a dispersion medium (preparation step), and a step of applying the composition for electrochemical device functional layers onto a substrate and drying it (functional layer formation step).

[0116] <Preparation Step> In the preparation step, a composition for an electrochemical device functional layer is prepared, including a first particulate polymer, a second particulate polymer, and a dispersion medium. The preparation step is not particularly limited, and for example, the first particulate polymer, the second particulate polymer, and the dispersion medium are mixed with, optionally, other components to obtain a composition for a functional layer. As the first particulate polymer, the second particulate polymer, the dispersion medium, and other components, those described above in the section "Composition for an electrochemical device functional layer" can be used. Here, the mixing method is not particularly limited, but in order to efficiently disperse each component, mixing is usually performed using a disperser as a mixing device. As the disperser, those described above in the section "Composition for an electrochemical device functional layer" can be used.

[0117] In addition, when the first particulate polymer and / or the second particulate polymer are prepared as an aqueous dispersion, the aqueous dispersion containing the first particulate polymer and / or the aqueous dispersion containing the second particulate polymer may be used as is to prepare a composition for a functional layer.

[0118] Furthermore, the functional layer composition prepared in the preparation step preferably contains water and has a pH of 5.0 or more, more preferably 6.0 or more, and preferably 12.0 or less, more preferably 11.0 or less. When the functional layer composition contains water and has a pH within the above range, the electrochemical element member can be provided with even better blocking resistance.

[0119] <Functional Layer Forming Step> In the functional layer forming step, the functional layer composition prepared in the preparation step is applied to a substrate and then dried to form a functional layer on the substrate. Specifically, the functional layer composition is applied to a substrate such as the current collector, separator substrate, or electrode substrate, or to the other layers formed on the substrate (hereinafter referred to as the "substrate, etc."), and then dried. Methods for forming a functional layer on a substrate, etc., include the following: 1) a method in which the functional layer composition is applied to the surface of the substrate, etc. (in the case of an electrode substrate, the surface on the electrode mixture layer side; the same applies hereinafter) and then dried; 2) a method in which the substrate, etc. is immersed in the functional layer composition and then dried; and 3) a method in which the functional layer composition is applied to a release substrate, dried to produce a functional layer, and then the resulting functional layer is transferred to the surface of the substrate, etc. Among these, method 1) is particularly preferred because it allows for easy control of the layer thickness of the functional layer. The method 1) specifically includes a step of applying a functional layer composition onto a substrate or the like (application step), and a step of drying the functional layer composition applied to the substrate or the like to form a functional layer (drying step).

[0120] - Coating process - In the coating process, the method for coating the functional layer composition onto the substrate or the like is not particularly limited, and examples thereof include a doctor blade method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method.

[0121] - Drying Step - In the drying step, the method for drying the functional layer composition on the substrate or the like is not particularly limited, and any known method can be used. Examples of drying methods include drying with warm air, hot air, or low-humidity air, vacuum drying, and drying by irradiation with infrared rays or electron beams. The drying temperature is preferably less than 200°C, and more preferably less than 150°C.

[0122] In the method for manufacturing a laminate for electrochemical elements of the present invention, the viscosity of the second particulate polymer contained in the composition for functional layer at pH 9.8 is within a predetermined range, and therefore, it is presumed that, in the process in which the composition for functional layer dries to form a functional layer, the second particulate polymer is suitably positioned on the surface of the first particulate polymer, and as a result, excellent blocking resistance can be imparted to the electrochemical element components.

[0123] (Electrochemical device) The electrochemical device of the present invention is characterized by comprising the laminate for electrochemical devices of the present invention described above. Since the electrochemical device of the present invention comprises the laminate for electrochemical devices of the present invention described above, it can exhibit excellent electrochemical characteristics (output characteristics, cycle characteristics).

[0124] The electrochemical device of the present invention is not particularly limited, and may be, for example, a lithium ion secondary battery or an electric double layer capacitor, and is preferably a lithium ion secondary battery.

[0125] Hereinafter, a lithium ion secondary battery will be described as an example of an electrochemical device of the present invention. The lithium ion secondary battery according to the present invention includes the above-described laminate for an electrochemical device of the present invention. More specifically, the lithium ion secondary battery includes a positive electrode, a negative electrode, a separator, and an electrolyte solution, and at least one of the positive electrode, the negative electrode, and the separator is made of the above-described laminate for an electrochemical device of the present invention.

[0126] 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.

[0127] <Positive Electrode and Negative Electrode> Specifically, the electrodes (positive electrode and negative electrode) can be electrodes formed by forming an electrode mixture layer on a current collector. The current collector can be made of a metal material such as iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, or platinum. Among these, it is preferable to use a current collector made of copper as the current collector for the negative electrode. Furthermore, it is preferable to use a current collector made of aluminum as the current collector for the positive electrode. Furthermore, a layer containing an electrode active material and a binder can be used as the electrode mixture layer.

[0128] <Electrolyte> As the electrolyte, an organic electrolyte solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. For example, in a lithium ion secondary battery, a lithium salt is used as the supporting electrolyte. For example, LiPF ６ , LiAsF ６ , LiBF ４ , LiSbF ６ , LiAlCl ４ , LiClO ４ , C.F. ３ SO ３ Li, C ４ F ９ SO ３ Li, CF ３ COOLi, (CF ３ CO) ２ NLi, (CF ３ SO ２ ) ２ NLi, (C ２ F ５ SO ２ Among them, LiPF is particularly preferred because it is easily soluble in solvents and shows a high degree of dissociation. ６ , LiClO ４ , C.F. ３ SO ３ Li is preferred. Note that one type of electrolyte may be used alone, or two or more types may be used in combination. Generally, the lithium ion conductivity tends to increase as the supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of supporting electrolyte.

[0129] The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte. For example, in lithium ion secondary batteries, carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), ethyl methyl carbonate (EMC), and vinylene carbonate (VC) are suitable. esters such as γ-butyrolactone and methyl formate are also suitable. Ethers such as 1,2-dimethoxyethane and tetrahydrofuran are also suitable. Sulfur-containing compounds such as sulfolane and dimethyl sulfoxide are also suitable. Mixtures of these solvents may also be used. Among these, carbonates are preferred due to their high dielectric constant and wide stable potential range. Generally, the lower the viscosity of the solvent used, the higher the lithium ion conductivity. Therefore, the lithium ion conductivity can be adjusted by the type of solvent. The concentration of the electrolyte in the electrolyte can be adjusted as appropriate. Known additives may also be added to the electrolyte.

[0130] <Method for Manufacturing Electrochemical Device> The electrochemical device of the present invention can be manufactured using the laminate for electrochemical devices of the present invention described above. Specifically, for example, when manufacturing a lithium ion secondary battery, a positive electrode and a negative electrode are stacked with a separator interposed therebetween, and the stack is rolled, folded, or otherwise placed in a battery container as needed. An electrolyte solution is then poured into the battery container and sealed, thereby manufacturing a lithium ion secondary battery. At least one of the positive electrode, negative electrode, and separator is manufactured using the laminate for electrochemical devices of the present invention described above. Here, the battery container may optionally contain an expanded metal, a fuse, an overcurrent prevention element such as a PTC element, a lead plate, or the like, to prevent pressure buildup within the battery and overcharging and discharging. The shape of the battery may be, for example, a coin type, a button type, a sheet type, a cylindrical type, a rectangular type, a flat type, or the like.

[0131] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified. Furthermore, in a polymer produced by copolymerizing multiple types of monomers, the proportion of a structural unit formed by polymerizing a certain monomer in the polymer usually coincides with the ratio (feed ratio) of that certain monomer to all monomers used in the polymerization of the polymer, unless otherwise specified. In the examples and comparative examples, various measurements and evaluations were carried out by the following methods.

[0132] <Viscosity of the Second Particulate Polymer at pH 9.8> The aqueous dispersions containing the second particulate polymer obtained in the Examples and Comparative Examples were adjusted to a solids concentration of 40% by mass. As an adjustment method, the aqueous dispersions (pH 9.8) containing the second particulate polymer prepared in the Examples and Comparative Examples were concentrated to the above solids concentration using an evaporator. After adjustment, the viscosity was measured using a Brookfield viscometer (manufactured by Toki Sangyo Co., Ltd., product name "TVB-10", rotation speed: 60 rpm), and the viscosity (η9.8) of the second particulate polymer at pH 9.8 was recorded. The temperature during viscosity measurement was 25°C. When measuring the viscosity of the second particulate polymer at pH 9.8 from the functional layer composition, the second particulate polymer may be separated from the functional layer composition using a centrifuge to prepare an aqueous dispersion containing the second particulate polymer. Specifically, 30 g of the functional layer composition (aqueous dispersion) was centrifuged at 5,000 rpm for 5 minutes using a refrigerated centrifuge (model number: CR21N, manufactured by Hitachi Koki Co., Ltd.), and the liquid phase containing the second particulate polymer was separated. The pH of the liquid phase was then adjusted to 9.8 using aqueous sodium hydroxide or the like, and the solids concentration was adjusted to 40% by mass in the same manner as described above. <Volume Average Particle Diameter of the First Particulate Polymer> As a measurement sample, the aqueous dispersion containing the first particulate polymer (equivalent to 0.1 g of solids) obtained in the Examples and Comparative Examples was weighed and placed in a beaker, and 0.1 mL of an alkylbenzenesulfonic acid aqueous solution (manufactured by Fujifilm Corporation, "Drywell") was added. 10 to 30 mL of a diluent (manufactured by Beckman Coulter, "Isoton II") was then added to the beaker, and the mixture was dispersed for 3 minutes using a 20 W (Watt) ultrasonic disperser. Thereafter, a particle size distribution (volume basis) of the measurement sample was obtained using a particle size analyzer (manufactured by Beckman Coulter, product name "Multisizer") under the conditions of aperture diameter: 20 μm, medium: Isoton II, and number of particles measured: 100,000. In the obtained particle size distribution, the volume average particle size of the first particulate polymer was determined as the particle size (D50) at which the cumulative volume calculated from the smallest diameter side became 50%. <Volume average particle size of second particulate polymer and binder> The volume average particle size of the second particulate polymer was measured by a laser diffraction scattering method.Specifically, the particle size distribution of the aqueous dispersions (adjusted to a solids concentration of 0.1% by mass) containing the second particulate polymer or binder prepared in the Examples and Comparative Examples was measured in accordance with JIS Z 8825 using a particle size distribution analyzer (Shimadzu Corporation, product name "SALD-2300"), and the particle diameter (D50) at which the cumulative volume calculated from the smallest diameter in the measured particle size distribution reached 50% was defined as the volume-average particle diameter. <Glass Transition Temperature of Particulate Polymer and Binder> The aqueous dispersions containing the first particulate polymer, the aqueous dispersions containing the second particulate polymer, and the aqueous dispersions containing the binder obtained in the Examples and Comparative Examples were dried to obtain the first particulate polymer, the second particulate polymer, and the binder in a dried state. Ion-exchange water was added to the dried first particulate polymer, the second particulate polymer, or the binder to prepare an aqueous dispersion containing 20% ​​by mass of the particulate polymer or the binder, which was used as the aqueous dispersion before drying. The aqueous dispersion before drying was dropped into a Teflon (registered trademark) Petri dish and dried for 24 hours in a hot air drying oven set at 25 ° C to obtain a measurement sample. Next, 10 mg of the measurement sample was weighed into an aluminum pan, and a differential scanning calorimetry (DSC) measurement was performed under the conditions specified in JIS Z 8703 using a differential scanning calorimetry (SII NanoTechnology Inc., "EXSTAR DSC6220") under a temperature range of -100 ° C to 500 ° C, a heating rate of 10 ° C / min, using an empty aluminum pan as a reference, to obtain a differential scanning calorimetry (DSC) curve. During this heating process, the glass transition temperature (° C) was determined as the intersection of the baseline just before the endothermic peak of the DSC curve where the differential signal (DDSC) is 0.05 mW / min / mg or more appears and the tangent to the DSC curve at the first inflection point that appears after the endothermic peak. <Electrolyte Swelling Degree of Second Particulate Polymer> The aqueous dispersions containing the second particulate polymer obtained in the Examples and Comparative Examples were formed into a film having a thickness of 2.0±0.5 mm on a horizontal table, dried in a vacuum dryer at 120°C for 10 hours, cut into pieces, and weighed to approximately 1 g. The mass of the obtained film piece was designated as W0. This film piece was immersed in an electrolyte (composition: LiPF with a concentration of 1.0 M) in an environment at 60°C. ６The film pieces were immersed in a solution (a mixed solvent of ethylene carbonate (EC) / diethyl carbonate (DEC) = 3 / 7 (volume ratio), with 2 vol% (solvent ratio) of vinylene carbonate added as an additive) for 3 days to allow swelling. The film pieces were then removed, the electrolyte solution on the surface was lightly wiped off, and the mass was measured. The mass of the swollen film piece was designated W1. The electrolyte swelling degree was calculated using the following formula: Electrolyte swelling degree (mass %) = {(W1 - W0) / W0} × 100 <Process Adhesion Between Separator with Functional Layer and Electrode> The separators with functional layer prepared in the examples and comparative examples were cut into 10 mm x 50 mm strips. Then, they were laminated on a negative electrode so that the separator faced the composite layer surface of the negative electrode to prepare test specimens. The negative electrodes used were those described in <Preparation of Negative Electrode>. The test specimen was pressed at a pressure of 3.0 MPa for 5 seconds using a plate press heated to 25°C. Next, the test specimen was placed with the surface facing the negative electrode current collector facing downward, and cellophane tape was attached to the surface facing the negative electrode current collector. The cellophane tape used was that specified in JIS Z1522. The cellophane tape was fixed to a horizontal test table. One end of the separator was then pulled vertically upward at a pulling rate of 50 mm / min to measure the stress when peeled. This measurement was performed three times, and the average stress value was calculated as the peel strength P1 and evaluated according to the following criteria. A higher peel strength P1 indicates higher process adhesion. A: Peel strength P1 is 3.0 N / m or more. B: Peel strength P1 is 2.0 N / m or more but less than 3.0 N / m. C: Peel strength P1 is 0.5 N / m or more but less than 2.0 N / m. D: Peel strength P1 is less than 0.5 N / m. <Blocking Resistance> The separators with functional layers (single-sided coated) prepared in the Examples and Comparative Examples were cut into two 10 mm x 50 mm strips. Next, a laminate was prepared by placing the functional layer surfaces of the separators facing each other to prepare a test specimen. This test specimen was placed in a laminate packaging material, and the packaging material was pressed for 1 minute at a temperature of 40°C and a load of 0.2 MPa (Condition 1). The test specimen was then removed, and cellophane tape was attached to the surface of the test specimen with the uncoated separator facing down. The cellophane tape used was that specified in JIS Z1522.The cellophane tape was fixed to a horizontal test table. The stress was measured when one end of the separator with the functional layer was pulled vertically upward at a pulling rate of 50 mm / min to peel it off. This measurement was performed three times, and the average stress was calculated as peel strength P2 and evaluated according to the following criteria. The test specimen obtained in the same manner as above was placed in a laminated packaging material, and the packaging material was pressed for 60 minutes at a temperature of 40°C and a load of 1.0 MPa (Condition 2). The average stress was calculated as peel strength P3 in the same manner as above and evaluated according to the following criteria. Smaller peel strengths P2 and P3 indicate stronger adhesion of the functional layer to the separator and better blocking resistance. Condition 1 (Load: 0.2 MPa, Pressing Time: 1 minute) A: The separator fell off before the peel strength test. B: Peel strength P2 is 0.0 N / m or more and less than 0.2 N / m C: Peel strength P2 is 0.2 N / m or more and less than 0.5 N / m D: Peel strength P2 is 0.5 N / m or more Condition 2 (load: 1.0 MPa, pressing time: 60 minutes) A: Peel strength P3 is 0.0 N / m or more and less than 0.5 N / m B: Peel strength P3 is 0.5 N / m or more and less than 2.0 N / m C: Peel strength P3 is 2.0 N / m or more and less than 4.0 N / m D: Peel strength P3 is 4.0 N / m or more <Output characteristics> After injection of the electrolyte, the lithium ion secondary batteries produced in the examples and comparative examples were allowed to stand at a temperature of 25°C for 5 hours. Next, the battery was charged to 17% SOC (State of Charge, depth of charge) at a constant current of 0.1C at 25°C, and then aged for 12 hours at 60°C. Then, the battery was discharged to a cell voltage of 3.0V at a constant current of 0.2C at 25°C. Thereafter, CC-CV charging (upper limit cell voltage 4.3V) was performed at a constant current of 0.2C, and CC discharging was performed at a constant current of 0.2C to a cell voltage of 3.0V. The third discharge capacity at this 0.2C was taken as the initial capacity CX. Thereafter, CC-CV charging (upper limit cell voltage 3.6V) was performed at a constant current of 0.2C, and CC discharging was performed at a constant current of 2.0C to a cell voltage of 3.0V, and the discharge capacity at this time was taken as CY. The 2.0C / 0.2C discharge capacity retention rate, which is expressed as (CY / CX)×100(%), was determined and evaluated according to the following criteria.A higher discharge capacity retention rate indicates better output characteristics (lower resistance) of the lithium-ion secondary battery. A: 2.0C / 0.2C discharge capacity retention rate is 60% or more. B: 2.0C / 0.2C discharge capacity retention rate is 55% or more but less than 60%. C: 2.0C / 0.2C discharge capacity retention rate is 50% or more but less than 55%. D: 2.0C / 0.2C discharge capacity retention rate is less than 50%. <Cycle Characteristics> After injecting the electrolyte, the lithium-ion secondary batteries prepared in the Examples and Comparative Examples were left standing at 25°C for 5 hours. Next, they were charged to a cell voltage of 3.65V using a constant current method at 25°C and 0.2C, and then aged for 12 hours at 60°C. Then, they were discharged to a cell voltage of 3.00V using a constant current method at 25°C and 0.2C. Thereafter, CC-CV charging (upper limit cell voltage 4.20 V) was performed using a 0.2 C constant current method, followed by CC discharging to 3.00 V using a 0.2 C constant current method. This 0.2 C charge / discharge cycle was repeated three times. Subsequently, 100 cycles of charge / discharge were performed at a cell voltage of 4.20-3.00 V and a charge / discharge rate of 1.0 C in an environment at a temperature of 25°C. The discharge capacity at the first cycle was defined as X1, and the discharge capacity at the 100th cycle as X2. The discharge capacities X1 and X2 were then used to calculate the capacity retention rate ΔC′ = (X2 / X1) × 100 (%), and the battery was evaluated according to the following criteria. A larger value for the capacity retention rate ΔC′ indicates that the secondary battery had better cycle characteristics at 100 cycles. It is presumed that the excellent cycle characteristics of the secondary battery at 100 cycles are due to the functional layer of the secondary battery being able to retain the electrolyte well. A: Capacity retention rate ΔC' is 95% or more. B: Capacity retention rate ΔC' is 92% or more and less than 95%. C: Capacity retention rate ΔC' is 90% or more and less than 92%. D: Capacity retention rate ΔC' is less than 90%.

[0133] Example 1 Preparation of Aqueous Dispersion Containing First Particulate Polymer Preparation of Monomer Composition A monomer composition was prepared by mixing 20.6 parts of styrene as an aromatic vinyl monomer, 0.5 parts of ethylene glycol dimethacrylate and 10.0 parts of glycidyl methacrylate as crosslinkable monomers, and 68.9 parts of 2-ethylhexyl acrylate as a (meth)acrylic acid ester monomer. Preparation of Dispersion 1.0 part of polyvinyl alcohol was added to 300 parts of ion-exchanged water adjusted to 60°C, and the mixture was stirred for 2 hours to dissolve the polyvinyl alcohol, preparing a dispersion. Polymerization Reaction A first particulate polymer was prepared by suspension polymerization. Specifically, the above-described monomer composition was added to the dispersion, and after further stirring, 2.0 parts of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, product name "Perbutyl O") as a polymerization initiator was added to obtain a mixed solution. The resulting mixture was subjected to high-shear stirring at 12,000 rpm for 1 minute using an in-line emulsifying disperser (manufactured by Pacific Machinery Works, product name "Cavitron") to form droplets of the monomer composition. The droplets of the monomer composition were formed. The droplets were placed in a reactor, heated to 90°C, and subjected to a polymerization reaction for 5 hours. Cooling was initiated when the reaction conversion rate reached 99.5%. The pH was further adjusted to 9.0 with an aqueous sodium hydroxide solution to obtain an aqueous dispersion containing a first particulate polymer. The first particulate polymer had a volume average particle diameter of 6.0 μm and a glass transition temperature of -25°C.

[0134] <Preparation of Aqueous Dispersion Containing Second Particulate Polymer> 70 parts of ion-exchanged water, 0.05 parts of sodium lauryl sulfate (manufactured by Kao Chemical Corporation, product name "EMAL (registered trademark) 2F") as an emulsifier, and 0.3 parts of ammonium persulfate as a polymerization initiator were supplied to a reactor equipped with a stirrer, the gas phase was replaced with nitrogen gas, and the temperature was raised to 80°C. Meanwhile, in a separate vessel, 50 parts of ion-exchanged water, 0.2 parts of sodium dodecylbenzenesulfonate as a dispersion stabilizer, 24.9 parts of n-butyl acrylate as a monomer having a solubility of less than 10 g in 100 mL of water, 50 parts of styrene, 0.1 parts of ethylene glycol dimethacrylate as a crosslinkable monomer and a monomer having a solubility of less than 10 g in 100 mL of water, 25.0 parts of methacrylic acid as a monomer having a solubility of 10 g or more in 100 mL of water, and 1.0 parts of tert-dodecyl mercaptan as a molecular weight modifier were mixed to prepare a monomer composition. The obtained monomer composition was continuously added to the above-mentioned reactor equipped with a stirrer over 5 hours to carry out polymerization. During the addition, the reaction was carried out at 80 ° C. After completion of the addition, the mixture was further stirred at 90 ° C. for 1 hour, and then the reaction was terminated. The pH was then adjusted to 9.8 with aqueous sodium hydroxide solution to obtain an aqueous dispersion containing a second particulate polymer. The second particulate polymer thus obtained had a volume average particle size of 0.25 μm, a glass transition temperature of 80° C., and a swelling degree in an electrolyte of 300%.

[0135] <Preparation of Binder> 70 parts of ion-exchanged water, 0.15 parts of sodium lauryl sulfate (manufactured by Kao Chemical Corporation, product name "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 gas, and the temperature was raised to 60°C. Meanwhile, in a separate vessel, 50 parts of ion-exchanged water, 0.5 parts of sodium dodecylbenzenesulfonate as a dispersion stabilizer, 91 parts of n-butyl acrylate as a (meth)acrylic acid ester monomer, 5 parts of methacrylic acid as an acid group-containing monomer, 2 parts of acrylonitrile as a nitrile group-containing monomer, and 1 part of allyl methacrylate and 1 part of allyl glycidyl ether as crosslinkable monomers were mixed to prepare a monomer composition. The resulting monomer composition was continuously added to the above-mentioned reactor equipped with a stirrer over a period of 4 hours to carry out polymerization. The reaction was carried out at 60°C during the addition. After the addition was completed, the mixture was stirred at 70°C for another 3 hours, and then the reaction was terminated. The pH was adjusted to 9.0 using an aqueous sodium hydroxide solution to obtain an aqueous dispersion containing a binder. The obtained binder was particulate, had a volume average particle diameter of 0.25 µm, and a glass transition temperature of -40°C.

[0136] <Preparation of Slurry for Heat-Resistant Layer> 0.5 parts of sodium polyacrylate as a dispersant was added to 92.8 parts of alumina (manufactured by Sumitomo Chemical Co., Ltd., product name "AKP3000", volume average particle diameter: 0.7 μm) as non-conductive heat-resistant particles, and ion-exchanged water was added to a solids concentration of 55%, followed by mixing using a ball mill. To the resulting mixture, 5 parts (solids equivalent) of the aqueous dispersion containing the binder, 1.5 parts of carboxymethyl cellulose as a thickener, and 0.2 parts of sodium dodecylbenzenesulfonate (manufactured by Kao Chemical Co., Ltd., "Neopelex G-15") as a dispersion stabilizer were added. Furthermore, the pH was adjusted to 7.0 using a 3% aqueous sodium hydroxide solution, and ion-exchanged water was added to a solids concentration of 40%, to obtain a slurry for the heat-resistant layer.

[0137] <Preparation of Functional Layer Composition> 91 parts (solids equivalent) of the aqueous dispersion containing the first particulate polymer and 4.8 parts (solids equivalent) of the aqueous dispersion containing the second particulate polymer were mixed. 0.5 parts of sodium polyacrylate as a dispersant was added, and ion-exchanged water was added to a solids concentration of 55%. The mixture was mixed using a ball mill to obtain a pre-mixing slurry. 2 parts (solids equivalent) of the aqueous dispersion containing the binder, 1.5 parts of carboxymethyl cellulose as a thickener, and 0.2 parts of sodium dodecylbenzenesulfonate ("Neopelex G-15" manufactured by Kao Chemical Corporation) as a dispersion stabilizer were added. Ion-exchanged water was then added to a solids concentration of 40%, and the pH was adjusted to 9.0 using aqueous sodium hydroxide solution to obtain a functional layer composition.

[0138] <Preparation of Separator with Functional Layer> A polyethylene microporous film (thickness: 12 μm) was prepared as a separator substrate. First, the heat-resistant layer slurry obtained as described above was applied to one side of this separator substrate by a bar coater method. Next, the separator substrate coated with the heat-resistant layer slurry was dried at 50°C for 10 minutes to form a heat-resistant layer. The same operation was performed on the other side of the separator substrate, producing a separator having a heat-resistant layer with a thickness of 2.0 μm on each side of the separator substrate. Next, the functional layer composition obtained as described above was applied to the heat-resistant layer by a bar coater method in a coating amount of 0.3 g / m. ２ The coated separator substrate was dried at 50°C for 10 minutes, and the weight was confirmed to produce a separator with a functional layer, in which a functional layer containing the first particulate polymer and the second particulate polymer was formed on the heat-resistant layer. Various measurements were then performed. The results are shown in Table 1.

[0139] <Preparation of Positive Electrode> LiCoO as a Positive Electrode Active Material ２100 parts of acetylene black (volume average particle diameter: 12 μm), 2 parts of acetylene black (manufactured by Denka Co., Ltd., "HS-100") as a conductive material, 2 parts of polyvinylidene fluoride (manufactured by Kureha Co., Ltd., "#7208") as a binder for the positive electrode composite layer in terms of solid content, and N-methylpyrrolidone as a solvent were mixed to a total solids concentration of 70%. These were mixed using a planetary mixer to prepare a positive electrode slurry composition. The positive electrode slurry composition was applied using a comma coater to a 20 μm thick aluminum foil current collector so that the film thickness after drying was approximately 150 μm, and then dried. This drying was performed by conveying the aluminum foil at a speed of 0.5 m / min in an oven at 60 ° C for 2 minutes. Thereafter, the aluminum foil was heat-treated at 120 ° C for 2 minutes to obtain a pre-press positive electrode blank. This pre-pressed positive electrode blank was rolled with a roll press to obtain a pressed positive electrode having a positive electrode mixture layer (thickness: 60 μm).

[0140] <Preparation of Negative Electrode> 33 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 63.5 parts of styrene, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator were placed in a 5 MPa pressure vessel equipped with a stirrer, thoroughly stirred, and then heated to 50 ° C to initiate polymerization. When the polymerization conversion rate reached 96%, the reaction was stopped by cooling to obtain a mixture containing a binder (SBR) for the negative electrode composite layer. A 5% aqueous sodium hydroxide solution was added to the mixture containing the binder for the negative electrode composite layer, and the pH was adjusted to 8. Unreacted monomers were removed by heated vacuum distillation. The mixture was then cooled to 30 ° C or below to obtain an aqueous dispersion containing the desired binder for the negative electrode composite layer. 80 parts of artificial graphite (volume average particle diameter: 15.6 μm) as the negative electrode active material (1), 16 parts of silicon-based active material SiOx (volume average particle diameter: 4.9 μm) as the negative electrode active material (2) were blended, and 2.5 parts of a 2% aqueous solution of carboxymethylcellulose sodium salt (manufactured by Nippon Paper Industries Co., Ltd., "MAC350HC") as a viscosity modifier was added in solids equivalent, and ion-exchanged water was mixed to adjust the solids concentration to 68%, and then further mixed at 25 ° C. for 60 minutes. The solids concentration was further adjusted to 62% with ion-exchanged water, and then further mixed at 25 ° C. for 15 minutes to obtain a mixed solution. To this mixed solution, 1.5 parts of the aqueous dispersion containing the binder for the negative electrode composite layer in solids equivalent and ion-exchanged water were added, and the final solids concentration was adjusted to 52%, and further mixed for 10 minutes to obtain a mixed solution. This mixed solution was degassed under reduced pressure to obtain a negative electrode slurry composition with good fluidity. The negative electrode slurry composition was applied to a 20 μm-thick copper foil current collector using a comma coater to a dried film thickness of approximately 150 μm, and then dried. This drying was performed by transporting the copper foil at a speed of 0.5 m / min through an oven at 60°C for 2 minutes. The copper foil was then heated at 120°C for 2 minutes to obtain a pre-pressed negative electrode blank. This pre-pressed negative electrode blank was rolled using a roll press to obtain a pre-pressed negative electrode having a negative electrode composite layer (thickness: 80 μm).

[0141] <Fabrication of Lithium-Ion Secondary Battery> The pressed positive electrode prepared as described above was cut into a size of 2.8 cm x 3.8 cm as a composite layer and placed with the surface on the positive electrode composite layer facing up. The separator with functional layer cut into a size of 3.5 cm x 4.5 cm was placed on the positive electrode composite layer. Furthermore, the pressed negative electrode prepared as described above was cut into a size of 3.0 cm x 4.0 cm and placed on the separator with functional layer with the surface on the negative electrode composite layer facing the separator. At this time, the surface of the separator with functional layer was placed facing the positive electrode, and the back surface of the separator with functional layer was placed facing the negative electrode, to obtain a laminate. This laminate was pressed at 50°C and 1 MPa to form a flat body, which was then wrapped in an aluminum packaging exterior as the exterior of the battery, and the electrolyte [a mixed solvent of ethylene carbonate (EC) / diethyl carbonate (DEC) / vinylene carbonate (VC) (volume mixing ratio: EC / DEC / VC = 68.5 / 30 / 1.5, LiPF as a supporting electrolyte] was added. ６ A solution of 1 mol / L of ethylenediaminetetraacetic acid (E2) dissolved in ethylenediaminetetraacetic acid (E2) at a concentration of 1 mol / L was poured into the battery, ensuring that no air remained. The opening of the aluminum packaging was then heat-sealed at 150°C to close the opening, completing a stacked lithium-ion secondary battery. Various measurements were then performed. The results are shown in Table 1.

[0142] Examples 2 to 9 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that the blending amount of the monomer and / or the blending amount of the molecular weight modifier used in preparing the second particulate polymer were changed as shown in Table 1, and a lithium ion secondary battery was obtained. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0143] (Example 10) In the preparation of the first particulate polymer, the amount of polyvinyl alcohol used in the [Preparation of Dispersion] step was changed from 1.0 part to 3.0 parts. The first particulate polymer, the second particulate polymer, the functional layer composition, the heat-resistant layer slurry, the separator with the functional layer, the positive electrode, and the negative electrode were prepared in the same manner as in Example 1, and a lithium ion secondary battery was obtained. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0144] Example 11 The first particulate polymer, the second particulate polymer, the functional layer composition, the heat-resistant layer slurry, the separator with the functional layer, the positive electrode, and the negative electrode were prepared in the same manner as in Example 1, except that the amount of polyvinyl alcohol used in the "Preparation of Dispersion" step in the preparation of the first particulate polymer was changed from 1.0 part to 5.0 parts, and the rotation speed during stirring using an in-line emulsifying disperser in the "Polymerization Reaction" step in the preparation of the first particulate polymer was changed from 12,000 rpm to 14,000 rpm. A lithium ion secondary battery was obtained. Various measurements and evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1.

[0145] (Example 12) In the preparation of the first particulate polymer, the amount of polyvinyl alcohol used in the [Preparation of Dispersion] step was changed from 1.0 part to 0.75 parts, but the same procedures as in Example 1 were carried out to prepare the first particulate polymer, the second particulate polymer, the functional layer composition, the heat-resistant layer slurry, the separator with the functional layer, the positive electrode, and the negative electrode, and a lithium ion secondary battery was obtained. Then, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0146] (Example 13) A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that the amount of polyvinyl alcohol used in the [Preparation of Dispersion] step in the preparation of the first particulate polymer was changed from 1.0 part to 0.50 part, and a lithium ion secondary battery was obtained. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0147] Example 14 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that in the preparation of the second particulate polymer, the amount of sodium lauryl sulfate (manufactured by Kao Chemical Corporation, product name "EMAL (registered trademark) 2F") used as an emulsifier was changed from 0.05 parts to 0.10 parts, and the amount of ammonium persulfate used as a polymerization initiator was changed from 0.3 parts to 0.7 parts. A lithium ion secondary battery was obtained. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0148] Example 15 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that in the preparation of the second particulate polymer, the amount of sodium lauryl sulfate (manufactured by Kao Chemical Corporation, product name "EMAL (registered trademark) 2F") used as an emulsifier was changed from 0.05 parts to 0.12 parts, and the amount of ammonium persulfate used as a polymerization initiator was changed from 0.3 parts to 0.5 parts. A lithium ion secondary battery was obtained. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0149] Example 16 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that in the preparation of the second particulate polymer, the amount of sodium lauryl sulfate (manufactured by Kao Chemical Corporation, product name "EMAL (registered trademark) 2F") used as an emulsifier was changed from 0.05 parts to 0.03 parts, and the amount of ammonium persulfate used as a polymerization initiator was changed from 0.3 parts to 0.15 parts. A lithium ion secondary battery was obtained. Various measurements and evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1.

[0150] Example 17 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that in the preparation of the second particulate polymer, the amount of sodium lauryl sulfate (manufactured by Kao Chemical Corporation, product name "EMAL (registered trademark) 2F") used as an emulsifier was changed from 0.05 parts to 0.01 parts, and the amount of ammonium persulfate used as a polymerization initiator was changed from 0.3 parts to 0.10 parts. A lithium ion secondary battery was obtained. Various measurements and evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1.

[0151] Example 18 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that a second particulate polymer prepared as described below was used, and a lithium-ion secondary battery was obtained. Various measurements and evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1. <Preparation of Aqueous Dispersion Containing Second Particulate Polymer> 40 parts of styrene, 30 parts of 1,3-butadiene, 30 parts of methacrylic acid, 0.20 parts of dodecyl diphenyl ether disulfonic acid sodium salt as an emulsifier, 180 parts of ion-exchanged water, and 0.3 parts of potassium persulfate as a polymerization initiator were added to a 5 MPa pressure vessel equipped with a stirrer to obtain a mixture A. Mixture A was thoroughly stirred and subjected to nitrogen substitution, and then heated to 40°C to initiate polymerization, followed by a reaction for 15 hours. During the reaction, when the reaction conversion rate of the monomer reached 80%, the internal temperature was increased to 60°C. When the polymerization conversion rate reached 97%, the reaction was stopped by cooling to obtain a mixture containing a polymer. Next, a 5% aqueous solution of sodium hydroxide was added to this mixture to adjust the pH to 9.8.

[0152] Example 19 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that a second particulate polymer prepared as described below was used, and a lithium-ion secondary battery was obtained. Various measurements and evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1. <Preparation of Aqueous Dispersion Containing Second Particulate Polymer> 40 parts of acrylonitrile, 30 parts of 1,3-butadiene, 30 parts of methacrylic acid, 0.20 parts of dodecyl diphenyl ether disulfonic acid sodium salt as an emulsifier, 180 parts of ion-exchanged water, and 0.3 parts of potassium persulfate as a polymerization initiator were added to a 5 MPa pressure vessel equipped with a stirrer to obtain a mixture A. Mixture A was thoroughly stirred and subjected to nitrogen substitution, and then heated to 40°C to initiate polymerization, followed by a reaction for 15 hours. During the reaction, when the reaction conversion rate of the monomer reached 80%, the internal temperature was increased to 60°C. When the polymerization conversion rate reached 97%, the reaction was stopped by cooling to obtain a mixture containing a polymer. Next, a 5% aqueous solution of sodium hydroxide was added to this mixture to adjust the pH to 9.8.

[0153] Example 20 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were produced in the same manner as in Example 1, except that in the "Preparation of Dispersion" step of preparing the first particulate polymer, polyvinyl alcohol was replaced with a colloidal dispersion containing magnesium hydroxide prepared as follows, and a lithium ion secondary battery was obtained. Various measurements and evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1. <Preparation of Colloidal Dispersion Containing Magnesium Hydroxide> A colloidal dispersion containing magnesium hydroxide as a metal hydroxide was prepared by gradually adding, with stirring, an aqueous solution obtained by dissolving 7.0 parts of sodium hydroxide in 50 parts of ion-exchanged water to an aqueous solution obtained by dissolving 10.0 parts of magnesium chloride in 200 parts of ion-exchanged water.

[0154] (Example 21) In the preparation of the second particulate polymer, except that 25 parts of vinyl sulfonic acid was used instead of 25 parts of methacrylic acid, the first particulate polymer, the second particulate polymer, the functional layer composition, the heat-resistant layer slurry, the separator with the functional layer, the positive electrode, and the negative electrode were prepared in the same manner as in Example 1, and a lithium ion secondary battery was obtained. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0155] Comparative Examples 1 to 3 A first particulate polymer, a second particulate polymer, a functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that in the preparation of the first particulate polymer and / or the second particulate polymer, the blending amounts of the monomers were changed as shown in Table 1, and a lithium ion secondary battery was obtained. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

[0156] Comparative Example 4 A functional layer composition, a heat-resistant layer slurry, a separator with a functional layer, a positive electrode, and a negative electrode were prepared in the same manner as in Example 1, except that the core-shell polymer prepared as described below in an example of Chinese Patent Application Publication No. 113410576 was used instead of the first particulate polymer, and the second particulate polymer was not used, and a lithium ion secondary battery was obtained. Various measurements and evaluations were then performed in the same manner as in Example 1. The results are shown in Table 1. <Preparation of Core-Shell Polymer> 20 parts of an emulsifier ("Neopelex G-15" manufactured by Kao Chemical Corporation) and 1,000 parts of ion-exchanged water were added to a reactor equipped with a stirrer and stirred uniformly at 30°C, and 10 parts of potassium persulfate was added, and nitrogen was passed through for 20 minutes. 500 parts of acrylic acid ester (mass fraction ratio of methyl acrylate: ethyl acrylate = 25:75) was slowly added dropwise using a constant pressure dropping funnel. After the addition was completed, the reaction was continued under controlled conditions for 2 hours, and when the reaction conversion rate exceeded 98%, core particles were obtained. 200 parts of acrylic acid ester monomer (mass fraction ratio of methyl acrylate: ethyl acrylate = 65:35), 10 parts of emulsifier, and 10 parts of potassium persulfate were added dropwise to the obtained core particles, and the temperature was raised to 60 ° C., and the reaction was carried out at a constant temperature for 2 hours. Then, dodecylthiol was added dropwise to control the molecular weight so that the glass transition temperature was 60 ° C., and the particle diameter was controlled to 4 μm, thereby obtaining core-shell particles. This was used as a first particulate polymer.

[0157] The results shown in Table 1 show that the compositions for electrochemical element functional layers of Examples 1 to 21, which contain a first particulate polymer and a second particulate polymer and in which the viscosity of the second particulate polymer at pH 9.8 is 50 mPa·s or more and 20,000 mPa·s or less, can impart excellent process adhesion and blocking resistance to electrochemical element members.

[0158] According to the present invention, it is possible to provide a composition for an electrochemical device functional layer that can form a functional layer for an electrochemical device that can impart excellent process adhesion and blocking resistance to an electrochemical device member.The present invention also provides a functional layer for an electrochemical device that can impart excellent process adhesion and blocking resistance to an electrochemical device member, and a laminate for an electrochemical device that includes the functional layer for an electrochemical device.The present invention also provides a method for producing the laminate for an electrochemical device, and an electrochemical device that includes the laminate for an electrochemical device.

Claims

1. A composition for an electrochemical element functional layer comprising a first particulate polymer and a second particulate polymer, wherein the second particulate polymer has a viscosity at pH 9.8 of 50 mPa·s or more and 20,000 mPa·s or less.

2. The composition for electrochemical element functional layers according to claim 1, wherein the first particulate polymer has a volume average particle diameter of 1.0 μm or more and 15.0 μm or less, and the second particulate polymer has a volume average particle diameter of 0.05 μm or more and less than 1.0 μm.

3. A composition for electrochemical element functional layers according to claim 1, wherein the second particulate polymer contains structural units derived from a monomer having a solubility of 10 g or more in 100 mL of water in a proportion of 5% by mass or more and 50% by mass or less.

4. A composition for electrochemical element functional layers according to claim 1, wherein the second particulate polymer contains structural units derived from a monomer having a solubility of less than 10 g in 100 mL of water in a proportion of 50% by mass or more and 95% by mass or less.

5. A composition for electrochemical element functional layers according to claim 1, wherein the second particulate polymer contains structural units derived from a monomer having a solubility of less than 5 g in 100 mL of water in a proportion of 50% by mass or more and 95% by mass or less.

6. The composition for an electrochemical device functional layer according to claim 1, wherein the second particulate polymer contains a crosslinkable monomer unit in a proportion of 0.01% by mass or more and 30% by mass or less.

7. The composition for an electrochemical element functional layer according to claim 1, wherein the first particulate polymer has a glass transition temperature of -50°C or higher and 50°C or lower, and the second particulate polymer has a glass transition temperature of 30°C or higher and 120°C or lower.

8. The composition for an electrochemical device functional layer according to claim 1, wherein the second particulate polymer has an electrolyte swelling rate of 100% or more and 600% or less.

9. The composition for an electrochemical device functional layer according to claim 1, further comprising water and having a pH of 5.0 or more and 12.0 or less.

10. A functional layer for an electrochemical device, which is formed using the composition for an electrochemical device functional layer according to any one of claims 1 to 9.

11. A laminate for an electrochemical device, comprising a substrate and a functional layer for an electrochemical device formed on the substrate, wherein the functional layer for an electrochemical device is the functional layer for an electrochemical device according to claim 10.

12. A method for manufacturing a laminate for an electrochemical element, comprising the steps of: preparing a composition for an electrochemical element functional layer, the composition comprising a first particulate polymer, a second particulate polymer, and a dispersion medium; and applying the composition for an electrochemical element functional layer onto a substrate and drying it, wherein the second particulate polymer has a viscosity at pH 9.8 of 50 mPa·s or more and 20,000 mPa·s or less.

13. The method for producing a laminate for an electrochemical device according to claim 12, wherein the composition for an electrochemical device functional layer contains water and has a pH of 5.0 or more and 12.0 or less.

14. An electrochemical device comprising the laminate for an electrochemical device according to claim 11.

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