JP6808931B2 - Composition for non-aqueous secondary battery adhesive layer, adhesive layer for non-aqueous secondary battery, and non-aqueous secondary battery - Google Patents

Description

The present invention relates to a composition for a non-aqueous secondary battery adhesive layer, a non-aqueous secondary battery adhesive layer, and a non-aqueous secondary battery.

Non-aqueous secondary batteries such as lithium-ion secondary batteries (hereinafter, may be abbreviated as "secondary batteries") are small and lightweight, have high energy density, and can be repeatedly charged and discharged. , Used in a wide range of applications. A secondary battery generally includes a positive electrode, a negative electrode, and a battery member such as a separator that separates the positive electrode and the negative electrode to prevent a short circuit between the positive electrode and the negative electrode.

Here, in recent years, in a secondary battery, a battery member provided with an adhesive layer for adhering the battery members to each other has been used. The degree of swelling with respect to the electrolytic solution (hereinafter, also referred to as "degree of swelling of the electrolytic solution") in order to suppress the deterioration of the low temperature output characteristics of the secondary battery due to the increase in the internal resistance of the secondary battery by providing the adhesive layer. A composition for an adhesive layer containing a particulate polymer having a core-shell structure having a polymer having a relatively high swelling degree as a core portion and a polymer having a relatively low degree of swelling of an electrolytic solution as a shell portion, or a composition formed by using such a composition. A separator base material having an adhesive layer has been proposed (see, for example, Patent Document 1). According to the adhesive layer composition or separator described in Patent Document 1, the low temperature output characteristics of the secondary battery can be improved.

International Publication No. 2015/005145

The conventional composition for an adhesive layer described in Patent Document 1 exhibits the characteristics of both polymers by coexisting a polymer having a high swelling degree and a polymer having a low swelling degree in one particulate polymer. The low temperature output characteristics of the secondary battery are improved.
Here, in the manufacture of a non-aqueous secondary battery, it is common to wind up the battery member, which is formed by forming a functional layer such as an adhesive layer on a base material such as a separator base material, and store and transport the battery member as it is. Therefore, the battery member is required to prevent the adjacent battery members from sticking to each other (that is, blocking) via the adhesive layer during storage and transportation. However, the above-mentioned conventional composition for an adhesive layer has room for improvement in that it suppresses blocking in addition to improving the low temperature output characteristics of the secondary battery.

Therefore, the present invention provides a non-aqueous secondary battery adhesive layer composition capable of exhibiting excellent blocking resistance in the adhesive layer and exhibiting excellent low temperature output characteristics in the secondary battery. The purpose is to do.
Another object of the present invention is to provide an adhesive layer for a non-aqueous secondary battery, which is excellent in blocking resistance and can exhibit excellent low temperature output characteristics in a secondary battery.
A further object of the present invention is to provide a non-aqueous secondary battery having excellent low temperature output characteristics.

The present inventor has conducted diligent studies for the purpose of solving the above problems. Then, the present inventor has used the composition for a non-aqueous secondary battery adhesive layer containing at least two kinds of particulate polymers having a volume average particle diameter D50 within a specific range as one of the particulate polymers. By using a particulate polymer having a core-shell structure having a core portion and a shell portion having a predetermined glass transition temperature, and using a particulate polymer having a relatively strong adhesiveness as the other particulate polymer, The present invention has been completed by finding that the blocking resistance of the adhesive layer can be improved and the low temperature output characteristics of the secondary battery can be improved.

That is, the present invention aims to advantageously solve the above problems, and the composition for a non-aqueous secondary battery adhesive layer of the present invention comprises a particulate polymer A, a particulate polymer B, and a binder. A composition for a non-aqueous secondary battery adhesive layer containing a coating material, wherein the particulate polymer A has at least one glass transition temperature of less than 80 ° C., and the particulate polymer B is a core. It has a core-shell structure including a portion and a shell portion covering the outer surface of the core portion having a glass transition temperature of 80 ° C. or higher, and further, the volume average particle diameter D50 _{A of the} particulate polymer _A and the particles. Both of the volume average particle diameters D50 _B of the state polymer B are 0.1 μm or more and 5 μm or less. As described above, both of the particles having a core-shell structure having a particulate polymer A having a volume average particle diameter D50 within a specific range and having a low glass transition temperature and adhesiveness and a shell portion having a relatively high glass transition temperature. By containing the state polymer B, an adhesive layer having high blocking resistance can be formed, and a composition capable of exhibiting excellent low temperature output characteristics in a secondary battery can be obtained.
The "glass transition temperature" of the particulate polymer can be measured by using the measuring method described in the examples of the present specification.

Here, in the composition for the non-aqueous secondary battery adhesive layer of the present invention, the content of the particulate polymer A is 2/3 times the content of the particulate polymer B on a mass basis. It is preferably 9 times or more and 9 times or less. By setting the content ratio of the two types of particulate polymers having different adhesiveness within a specific range in this way, the blocking resistance of the adhesive layer can be further improved and the adhesiveness of the adhesive layer can be improved. Further, the low temperature output characteristics of the secondary battery can be further improved.

Further, in the composition for the non-aqueous secondary battery adhesive layer of the present invention, the volume average particle diameter D50 _B of the particulate polymer _B is 0.5 times the volume average particle diameter D50 _A of the particulate polymer A. It is preferably 5 times or more and 5 times or less. By containing the two particulate polymers in which the ratio of the volume average particle diameters is in a specific range in this way, the blocking resistance of the adhesive layer can be further improved and the adhesive density can be reduced. This is because the low temperature output characteristics of the secondary battery can be improved.

The present invention also aims to advantageously solve the above problems, and the adhesive layer for a non-aqueous secondary battery of the present invention is any of the above-mentioned compositions for a non-aqueous secondary battery adhesive layer. It is characterized in that it is formed using. As described above, by using any of the above-mentioned compositions, it is possible to obtain an adhesive layer which is excellent in blocking resistance and can exhibit excellent low temperature output characteristics in a secondary battery.

Furthermore, the present invention aims to advantageously solve the above problems, and the non-aqueous secondary battery of the present invention is characterized by including the above-mentioned adhesive layer for a non-aqueous secondary battery. As described above, by using the above-mentioned adhesive layer, a non-aqueous secondary battery having excellent low temperature output characteristics can be obtained.

According to the present invention, a composition for a non-aqueous secondary battery adhesive layer can be obtained, which can exhibit excellent blocking resistance in the adhesive layer and exhibit excellent low temperature output characteristics in the secondary battery. Be done.
Further, according to the present invention, it is possible to obtain an adhesive layer for a non-aqueous secondary battery which is excellent in blocking resistance and can exhibit excellent low temperature output characteristics in a secondary battery.
Further, according to the present invention, a non-aqueous secondary battery having excellent low temperature output characteristics can be obtained.

Hereinafter, embodiments of the present invention will be described in detail.
Here, the composition for a non-aqueous secondary battery adhesive layer of the present invention can be used when forming the non-aqueous secondary battery adhesive layer of the present invention. Further, the adhesive layer for a non-aqueous secondary battery of the present invention can be used when adhering battery members to each other. The non-aqueous secondary battery of the present invention is characterized by including the adhesive layer for the non-aqueous secondary battery of the present invention.

(Composition for non-aqueous secondary battery adhesive layer)
The composition for a non-aqueous secondary battery adhesive layer of the present invention contains a particulate polymer A, a particulate polymer B, and a binder. And the particulate polymer A has at least one glass transition temperature of less than 80 ° C. Further, the particulate polymer B has a core-shell structure including a core portion and a shell portion covering the outer surface of the core portion having a glass transition temperature of 80 ° C. or higher. Further, the volume average particle diameter D50 _A of the particulate polymer _A and the volume average particle diameter D50 _{B of the} particulate polymer _B are 0.1 μm or more and 5 μm or less.
Here, the reason why the above-mentioned excellent effects can be obtained by blending the above-mentioned particulate polymers A and B with the composition for the non-aqueous secondary battery adhesive layer together with the binder. Although it is not clear, it is presumed to be as follows.
That is, the particulate polymer B having a core-shell structure has a relatively high glass transition temperature in the shell portion, and functions mainly to improve blocking resistance when blended in the composition for an adhesive layer. On the other hand, the particulate polymer A has at least one glass transition temperature of less than 80 ° C., which is lower than that of the particulate polymer B, and is rich in adhesiveness. The presence of the particulate polymers A and B in the adhesive layer prevents the adhesive layer from being blocked by the presence of the particulate polymer B while maintaining the adhesiveness of the adhesive layer by the particulate polymer A. It is presumed that it will be possible to suppress it.
Further, in order to improve the ion diffusivity in the secondary battery, it is preferable to provide a gap in the adhesive layer through which ions contributing to the battery reaction such as lithium ions can pass. Therefore, as a result of further studies by the present inventors, the adhesive layer is adhered by blending the particulate polymers A and B having a volume average particle diameter D50 in a specific range of 0.1 μm or more and 5 μm or less. It was newly found that the low temperature output characteristics of the secondary battery can be improved in addition to the properties and blocking resistance. This makes it easy to create gaps of a size suitable for the passage of ions that contribute to the battery reaction between the particulate polymers A and B having the volume average particle diameter D50 in the specific range, whereby the adhesive layer It is presumed that this is because the resistance can be lowered and the low temperature output characteristics of the secondary battery can be improved.

<Particulate polymer>
The properties and composition of the particulate polymers A and B contained in the composition for the non-aqueous secondary battery adhesive layer of the present invention will be described below. Here, the particulate polymer is a component dispersed in the composition or slurry while maintaining the particle shape. The particulate polymer may have a particle shape or any other shape in the adhesive layer formed by using the composition.

-Characteristics of particulate polymer-
[Particulate Polymer A]
The particulate polymer A having at least one glass transition temperature of less than 80 ° C. improves the adhesiveness in the adhesive layer using the composition for the non-aqueous secondary battery adhesive layer of the present invention, and makes the adhesive layer. It is a component that can bring out excellent low-temperature output characteristics in the secondary battery provided. Here, depending on the structure of the particulate polymer A, the above-mentioned "at least one glass transition temperature of less than 80 ° C." corresponds to the glass transition temperature of any part (or the whole) of the particulate polymer A. I will briefly explain whether it is a thing. That is, when the particulate polymer A does not have a core-shell structure and is composed of a single polymer, the above-mentioned "at least one glass transition temperature of less than 80 ° C." is the glass transition of the entire particulate polymer A. The temperature. On the other hand, when the particulate polymer A has a core-shell structure, the "at least one glass transition temperature of less than 80 ° C." is preferably the glass transition temperature of the shell portion.

[[Glass transition temperature of particulate polymer A]]
Further, the above-mentioned "at least one glass transition temperature of less than 80 ° C." is preferably less than 80 ° C., more preferably less than 75 ° C., and further preferably less than 70 ° C. Further, the "at least one glass transition temperature of less than 80 ° C." is usually 20 ° C. or higher. When the "at least one glass transition temperature of less than 80 ° C." of the particulate polymer A is within the above range, the adhesiveness of the adhesive layer formed by using the composition between the battery members can be improved. ..

As a method for adjusting "at least one glass transition temperature of less than 80 ° C." of the particulate polymer A, for example, the type and amount of the monomer used for preparing the particulate polymer are appropriately selected. There is a choice.

[[Structure of Particulate Polymer A]]
The particulate polymer A may have any structure, for example, individual polymers having a particle shape may be individually present, and individual polymers having a particle shape are present in contact with each other. Alternatively, individual polymers having a particle shape may be present as a composite.
When the individual particles are present in contact or in combination, for example, a core-shell structure may have a core portion and a shell portion that covers the outer surface of the core portion. Further, the shell portion may partially cover the outer surface of the core portion. That is, the shell portion of the particulate polymer A may cover the outer surface of the core portion, but may not cover the entire outer surface of the core portion.

[[Volume average particle diameter D50 _{A of} particulate polymer _A ]]
The volume average particle diameter D50 _A of the particulate polymer A is preferably 0.1 μm or more, more preferably 0.3 μm or more, further preferably 0.4 μm or more, and 5 μm or less. It is preferably 3 μm or less, and particularly preferably 2 μm or less. When the volume average particle diameter D50 _A of the particulate polymer A is not more than the above lower limit value, it is possible to suppress the excessive increase in the cohesiveness of the particulate polymer A and to form the particulate polymer A in the adhesive layer. It can be appropriately dispersed, the increase in internal resistance of the secondary battery provided with the adhesive layer can be suppressed, and the low temperature output characteristics of the secondary battery can be improved. When the volume average particle diameter D50 _{A of the} particulate polymer A is not more than the above upper limit value, the adhesiveness of the adhesive layer can be further improved.

The volume average particle diameter D50 _A of the particulate polymer A can be measured by using the measuring method described in the examples of the present specification.
When the particulate polymer A has a core-shell structure, the total particle size including the core portion and the shell portion is preferably within the above range.
Further, the volume average particle diameter D50 _A of the particulate polymer _A can be adjusted based on the amount of emulsifier or monomer added at the time of polymerization.

[Particulate Polymer B]
The particulate polymer B having a core-shell structure including a core portion and a shell portion covering the outer surface of the core portion having a glass transition temperature of 80 ° C. or higher is a component capable of improving the blocking resistance of the adhesive layer. ..

[[Glass transition temperature of particulate polymer B]]
Further, the glass transition temperature of the shell portion of the particulate polymer B needs to be 80 ° C. or higher, preferably 90 ° C. or higher, and more preferably 100 ° C. or higher. The glass transition temperature of the shell portion of the particulate polymer B is usually 300 ° C. or lower. When the glass transition temperature of the shell portion of the particulate polymer B is equal to or higher than the above lower limit value, the particulate polymer B is less likely to be deformed in the adhesive layer, the blocking resistance is improved, and the adhesive layer is provided. The low temperature output characteristics of the next battery can be improved. The glass transition temperature of the particulate polymer B can be adjusted in the same manner as that of the particulate polymer A.

Further, the glass transition temperature of the core portion of the particulate polymer B is preferably less than 80 ° C, more preferably less than 75 ° C, and even more preferably less than 70 ° C. The glass transition temperature of the core portion of the particulate polymer B is usually 20 ° C. or higher. When the glass transition temperature of the core portion of the particulate polymer B is within the above range, the particulate polymer B can be provided with a function of improving the blocking resistance of the adhesive layer and a function of improving the adhesiveness. Because it can be done.

[[Volume average particle diameter D50 _{B of} particulate polymer _B ]]
The volume average particle diameter D50 _B of the particulate polymer B is preferably 0.1 μm or more, more preferably 0.3 μm or more, further preferably 0.5 μm or more, and 5 μm or less. It is preferably 3 μm or less, more preferably 2 μm or less. When the volume average particle diameter D50 _B of the particulate polymer B is not more than the above lower limit value, it is possible to suppress the excessive increase in the cohesiveness of the particulate polymer B and to form the particulate polymer B in the adhesive layer. It can be appropriately dispersed, the increase in the internal resistance of the adhesive layer can be suppressed, and the low temperature output characteristics of the secondary battery can be improved. When the volume average particle diameter D50 _{B of the} particulate polymer B is not more than the above upper limit value, the adhesiveness of the adhesive layer can be further improved. The volume average particle diameter D50 _B of the particulate polymer _B can be adjusted in the same manner as in the case of the particulate polymer A. Further, the volume average particle diameter D50 _B of the particulate polymer B is the volume average particle diameter of the entire particulate polymer B including the core portion and the shell portion.

[[Structure of Particulate Polymer B]]
The particulate polymer B has a core-shell structure including a core portion and a core portion and a shell portion that covers the outer surface of the core portion. Preferably, the shell portion of the particulate polymer B is a partially coated embodiment that covers the outer surface of the core portion but does not cover the entire outer surface of the core portion. For example, in the particulate polymer B having a core-shell structure, the particle-shaped shell portions may be present in contact with each other so as to partially cover the particle-shaped core portion.

The particulate polymer B may include any component other than the above-mentioned core portion and shell portion as long as the desired effect is not significantly impaired. Specifically, for example, the organic particles may have a portion formed of a polymer different from the core portion inside the core portion. To give a specific example, the seed particles used when the organic particles are produced by the seed polymerization method may remain inside the core portion.

-Composition of particulate monomer-
[Particulate Polymer A]
The particulate polymer A can have any composition as long as the particulate polymer has at least one glass transition temperature of less than 80 ° C. The monomer that can be used to prepare the particulate polymer A is not particularly limited, and is, for example, a vinyl chloride-based monomer such as vinyl chloride or vinylidene chloride; a vinyl acetate-based single amount such as vinyl acetate. Body: Aromatic vinyl monomers such as styrene, α-methylstyrene, styrenesulfonic acid, butoxystyrene, vinylnaphthalene; Vinylamine-based monomers such as vinylamine; Vinylamide-based monomers such as N-vinylformamide and N-vinylacetamide. Quantities; (meth) acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, 2-ethylhexyl acrylate; N-hydroxymethyl (meth) acrylamide, acrylamide, (Meta) acrylamide monomer such as methacrylamide; (meth) acrylonitrile monomer such as acrylonitrile and methacrylonitrile; fluorine-containing such as 2- (perfluorohexyl) ethyl methacrylate and 2- (perfluorobutyl) ethyl acrylate Examples thereof include (meth) acrylate monomers; maleimides; maleimide derivatives such as phenylmaleimide; and diene monomers such as 1,3-butadiene and isoprene. In addition, one of these may be used alone, or two or more of them may be used in combination at any ratio.
In the present invention, (meth) acrylate means acrylate and / or methacrylate, (meth) acrylamide means acrylamide and / or methacrylamide, and (meth) acrylonitrile means acrylonitrile and / or Methacrylonitrile.

Further, the particulate polymer A may contain an acid group-containing monomer unit. Here, as the acid group-containing monomer, a monomer having an acid group, for example, a monomer having a carboxylic acid group, a monomer having a sulfonic acid group, a monomer having a phosphoric acid group, and , Monomer having a hydroxyl group can be mentioned.

Examples of the monomer having a carboxylic acid group include monocarboxylic acid and dicarboxylic acid. Examples of the monocarboxylic acid include acrylic acid, methacrylic acid, crotonic acid and the like. Examples of the dicarboxylic acid include maleic acid, fumaric acid, itaconic acid and the like.
Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth) allyl sulfonic acid, ethyl (meth) acrylic acid-2-sulfonate, and 2-acrylamide-2-methyl. Examples thereof include propanesulfonic acid and 3-allyloxy-2-hydroxypropanesulfonic acid.
Further, examples of the monomer having a phosphate group include -2- (meth) acryloyloxyethyl phosphate, methyl-2- (meth) acryloyloxyethyl phosphate, and ethyl phosphate- (meth) acryloyloxyethyl. And so on.
Examples of the monomer having a hydroxyl group include -2-hydroxyethyl acrylate, -2-hydroxypropyl acrylate, -2-hydroxyethyl methacrylate, and -2-hydroxypropyl methacrylate.
In the present invention, (meth) allyl means allyl and / or metharyl, and (meth) acryloyl means acryloyl and / or methacrylic.

Further, the particulate polymer A preferably contains a crosslinkable monomer unit in addition to the above-mentioned monomer unit. The crosslinkable monomer is a monomer capable of forming a crosslinked structure during or after polymerization by heating or irradiation with energy rays.

Examples of the crosslinkable monomer include a polyfunctional monomer having two or more polymerization-reactive groups in the monomer. Examples of such a polyfunctional monomer include divinyl compounds such as divinylbenzene; di (meth) such as ethylene dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, and 1,3-butylene glycol diacrylate. ) Acrylic acid ester compounds; Tri (meth) acrylic acid ester compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate; Eethylene unsaturated monomers containing epoxy groups such as allylglycidyl ether and glycidyl methacrylate; etc. Can be mentioned. In addition, one of these may be used alone, or two or more of them may be used in combination at any ratio.

In preparing the particulate polymer A, the combination and blending ratio of the various monomers may be arbitrarily changed according to the glass transition temperature, particle size, structure, etc. of the target particulate polymer A. it can.

[Particulate Polymer B]
The particulate polymer B can have any composition as long as the glass transition temperature of the shell portion can be 80 ° C. or higher. In preparing the particulate polymer B, the above-mentioned monomer can be used for the particulate polymer A. Further, in preparing the particulate polymer B, the combination and blending ratio of the various monomers can be arbitrarily changed according to the properties of the target particulate polymer.

-Method of preparing particulate polymer-
The above-mentioned particulate polymers A and B can be prepared by a known polymerization method without particular limitation. The polymerization mode is not particularly limited, and any mode such as a solution polymerization method, a suspension polymerization method, a massive polymerization method, and an emulsion polymerization method can be used. As the polymerization method, any method such as ionic polymerization, radical polymerization, living radical polymerization and the like can be used. Further, in the emulsion polymerization, seed polymerization using seed particles may be adopted. Further, when preparing the particulate polymer A / B having a core-shell structure, for example, a multi-step emulsion polymerization method can be mentioned. Then, as the multi-step emulsification polymerization method, for example, a known polymerization method described in International Publication No. 2015/005145 can be used. Further, as the emulsifier, dispersant, polymerization initiator, chain transfer agent and the like used in the multi-step emulsion polymerization, commonly used ones can be used, and the amount used may be the amount generally used. it can.

Specifically, as a polymerization procedure of the multi-step emulsion polymerization method, first, a monomer and an emulsifier forming a core portion are mixed with water as a solvent, then a polymerization initiator is added, and the core is emulsion-polymerized. A particulate polymer constituting the part is obtained. Further, by polymerizing the monomer forming the shell portion in the presence of the particulate polymer constituting the core portion, a particulate polymer having a core-shell structure can be obtained. At this time, from the viewpoint of partially covering the outer surface of the core portion with the shell portion, it is preferable that the monomer of the polymer in the shell portion is divided into a plurality of times or continuously supplied to the polymerization system. By dividing the monomer of the polymer in the shell portion into a polymerization system or supplying it continuously, the polymer constituting the shell portion is formed in the form of particles, and the particles are bonded to the core portion. , A shell portion that partially covers the core portion can be formed.
Further, when a monomer having a low affinity for the polymerization solvent is used as the monomer forming the polymer of the shell portion, the shell portion that partially covers the core portion tends to be easily formed. When the polymerization solvent is water, the monomer forming the polymer in the shell portion preferably contains a hydrophobic monomer, and particularly preferably contains an aromatic vinyl monomer as described above.
Further, if the amount of emulsifier used is reduced, it tends to be easy to form a shell portion that partially covers the core portion, and by appropriately adjusting the amount of emulsifier, a shell portion that partially covers the core portion can be formed. it can.
The diameter of the core portion of the particulate polymer A / B having a core-shell structure, the particle diameter of the particulate polymer A / B having a core-shell structure, and the diameter of the shell portion when the shell portion has a particle shape are For example, the desired range can be obtained by adjusting the amount of the emulsifier, the amount of the monomer, and the like.

As the emulsifier, dispersant, polymerization initiator, polymerization aid and the like used for the polymerization, those generally used can be used, and the amount used can also be the amount generally used.

-Content ratio of particulate polymers A and B-
The content ratio of the particulate polymer A and the particulate polymer B is such that the content of the particulate polymer A is 2/3 times or more on a mass basis with respect to the content of the particulate polymer B. Is preferable, 1 times or more is more preferable, 9 times or less is preferable, and 4 times or less is more preferable. By setting the content of the particulate polymer A to the above lower limit value or more, the adhesiveness of the adhesive layer can be improved and the low temperature output characteristics of the secondary battery can be improved. Further, by setting the content of the particulate polymer A to the above upper limit value or less, the blocking resistance of the adhesive layer can be improved.

-Ratio of volume average particle size D50 of particulate polymer-
Here, the volume average particle size D50 _B of the particulate polymer _B is preferably 0.5 times or more, more preferably 0.6 times or more, more preferably 0.7 times the volume average particle size D50 _A of the particulate polymer A. More than twice, more preferably five times or less, more preferably four times or less, further preferably three times or less, and particularly preferably two times or less. By setting the volume average particle diameter D50 of the particulate polymers A and B within the above range, the ion diffusivity of the adhesive layer can be improved and the low temperature output characteristics of the secondary battery can be improved. In particular, if it is at least the above lower limit value, the blocking resistance property of the adhesive layer can be improved, and if it is at least the above upper limit value, the adhesiveness between the battery members of the adhesive layer can be improved.

<Bundling material>
The composition for the non-aqueous secondary battery adhesive layer contains a binder in addition to the above-mentioned particulate polymers A and B. Here, the binder is a component that makes it difficult for the particulate polymers A and B to fall off from the adhesive layer, and is a component different from the particulate polymers A and B. As the binder, a known binder, for example, a thermoplastic elastomer can be used without particular limitation as long as it can perform such a function. As the thermoplastic elastomer, a conjugated diene polymer and an acrylic polymer are preferable, and an acrylic polymer is more preferable.
Here, the conjugated diene-based polymer refers to a polymer containing a conjugated diene monomer unit, and specific examples of the conjugated diene-based polymer include aromatic vinyl such as a styrene-butadiene copolymer (SBR). Examples thereof include a polymer containing a monomer unit and an aliphatic conjugated diene monomer unit, acrylic rubber (NBR) (a polymer containing an acrylonitrile unit and a butadiene unit), and a styrene-butadiene copolymer is preferable. Further, the acrylic polymer refers to a polymer containing a (meth) acrylic acid ester monomer unit. Here, as the (meth) acrylic acid ester monomer capable of forming the (meth) acrylic acid ester monomer unit, the same monomer as that used for preparing the particulate polymer may be used. it can.
One type of these binders may be used alone, or two or more types may be used in combination.

The binder may be in the form of particles, but in this case, the particle size is preferably smaller than that of the particulate polymers A and B, and is usually 0.05 μm or more and less than 0.4 μm. This is because when the binder is in the form of particles and the particle size is smaller than that of the particulate polymers A and B, it is possible to effectively suppress the detachment of the particulate polymers A and B from the adhesive layer. is there.

<Other ingredients>
The composition for the non-aqueous secondary battery adhesive layer may contain any other components in addition to the above-mentioned particulate polymer and binder. Examples of these other components include known additives such as wetting agents, viscosity modifiers, and electrolyte additives. One of these other components may be used alone, or two or more thereof may be used in combination.

-Contents of particulate polymers A and B-
The total content of the particulate polymers A and B in the composition for the non-aqueous secondary battery adhesive layer of the present invention is 50, where the total solid content of the particulate polymers A and B and the binder is 100% by mass. It is preferably 0% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, preferably 95% by mass or less, and more preferably 90% by mass or less. It is preferably 85% by mass or less, and more preferably 85% by mass or less.

<Method of preparing composition for non-aqueous secondary battery adhesive layer>
Here, the method for preparing the composition for the non-aqueous secondary battery adhesive layer is not particularly limited, but includes, for example, particulate polymers A and B, a binder, and any other component such as a wetting agent. Is dissolved or dispersed in a solvent to prepare an adhesive composition. Specifically, a disperser such as a ball mill, a sand mill, a pigment disperser, a grinder, an ultrasonic disperser, a homogenizer, a planetary mixer, a bead mill, a roll mill, or a fill mix is used to combine the particulate polymers A and B. , A binder and other components are dispersed or dissolved in a solvent to prepare a composition for a non-aqueous secondary battery adhesive layer.

(Adhesive layer for non-aqueous secondary batteries)
The adhesive layer for a non-aqueous secondary battery adhesive layer described above can be used to form an adhesive layer on an appropriate base material. Specifically, the non-aqueous secondary battery adhesive layer can be formed by drying the composition for the non-aqueous secondary battery adhesive layer on an appropriate base material. That is, the adhesive layer for a non-aqueous secondary battery of the present invention comprises a dried product of the above-mentioned composition for a non-aqueous secondary battery adhesive layer, and usually contains the above-mentioned organic particles and the above-mentioned binder for the adhesive layer. Optionally, it contains the above other components. When the above-mentioned particulate polymer A / B and / or the binder for the adhesive layer contains a crosslinkable monomer unit, the slurry composition is dried between the crosslinkable monomer units. Crosslinks may be formed at the time or during a heat treatment optionally performed after drying (that is, the adhesive layer for a non-aqueous secondary battery is for the above-mentioned particulate polymer A / B and / or the adhesive layer. It may contain a crosslinked product of the binder). The preferable abundance ratio of each component contained in the non-aqueous secondary battery adhesive layer is the same as the preferable abundance ratio of each component in the non-aqueous secondary battery adhesive layer composition.
Further, when the particulate polymer A / B having a core-shell structure is blended in the composition for the adhesive layer, the core shell even if the shape of the organic particles as a whole is changed from the original particle shape. The structure itself is preferably maintained.
Since the adhesive layer for a non-aqueous secondary battery of the present invention contains the above-mentioned particulate polymers A and B, it is excellent in blocking resistance and has low temperature output characteristics of the secondary battery provided with the adhesive layer. Can be made excellent.

<Base material>
The base material forming the adhesive layer is not particularly limited. For example, when the adhesive layer is used as a member constituting a part of the separator, the separator base material can be used as the base material, and the electrode. When an adhesive layer is used as a member constituting a part of the above, an electrode base material formed by forming an electrode mixture layer on a current collector can be used as the base material. Further, the usage of the adhesive layer formed on the base material is not particularly limited, and for example, the adhesive layer may be formed on the separator base material or the like and used as it is as a battery member such as the separator, or on the electrode base material. The adhesive layer may be formed on the base material and used as an electrode, or the adhesive layer formed on the release base material may be peeled off from the base material once and attached to another base material to be used as a battery member. ..
However, from the viewpoint of improving the manufacturing efficiency of the battery member by omitting the step of peeling the release base material from the adhesive layer, it is preferable to use a separator base material or an electrode base material as the base material.

[Separator base material]
The separator base material for forming the adhesive layer is not particularly limited, and for example, those described in JP2012-204303 can be used. Among these, the film thickness of the entire separator can be reduced, and as a result, the ratio of the electrode active material in the secondary battery can be increased and the capacity per volume can be increased. A microporous film made of a resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferable.
It is also possible to apply any layer other than the adhesive layer that can exhibit the desired function to the separator base material.

[Electrode substrate]
The electrode base material (positive electrode base material and negative electrode base material) forming the adhesive layer is not particularly limited, and examples thereof include an electrode base material in which an electrode mixture layer is formed on a current collector.
Here, the components in the current collector, the electrode mixture layer (for example, the electrode active material (positive electrode active material, the negative electrode active material) and the binder for the electrode mixture layer (the binder for the positive electrode mixture layer, the negative electrode combination). As a method for forming the electrode mixture layer on the current collector, a known method can be used, for example, the one described in Japanese Patent Application Laid-Open No. 2013-145763. be able to.
The electrode base material may include an arbitrary layer having an desired function other than the adhesive layer as a part thereof.

[Release base material]
The release base material that forms the adhesive layer is not particularly limited, and a known release base material can be used.

<Method of forming an adhesive layer for non-aqueous secondary batteries>
Examples of the method for forming the adhesive layer on the substrate such as the separator substrate and the electrode substrate described above include the following methods. :
1) A method in which the composition for an adhesive layer is applied to the surface of a separator base material or an electrode base material (in the case of an electrode base material, the surface on the electrode mixture layer side, the same applies hereinafter), and then dried;
2) A method of immersing the separator base material or the electrode base material in the composition for the adhesive layer and then drying it;
3) A method in which the composition for an adhesive layer is applied onto a release base material and dried to produce an adhesive layer, and the obtained adhesive layer is transferred to the surface of a separator base material or an electrode base material.
Among these, the method 1) is particularly preferable because it is easy to control the film thickness of the adhesive layer. Specifically, the method of 1) includes a step of applying the composition for an adhesive layer on a separator base material or an electrode base material (coating step) and a step of applying the composition for an adhesive layer on the separator base material or the electrode base material. A step (drying step) of drying the composition to form an adhesive layer is provided.

In the coating step, the method of coating the composition for the adhesive layer on the separator base material or the electrode base material is not particularly limited, and for example, a spray coating method, a doctor blade method, a reverse roll method, a direct roll method, a gravure method, etc. Examples include the extraction method and the brush coating method. Of these, the gravure method is preferable from the viewpoint of forming a thinner adhesive layer.
Further, in the drying step, the method for drying the composition for the adhesive layer on the substrate is not particularly limited, and a known method can be used, for example, drying with warm air, hot air, low humidity air, vacuum drying, infrared rays, or the like. A drying method by irradiating an electron beam or the like can be mentioned. The drying conditions are not particularly limited, but the drying temperature is preferably 30 to 80 ° C., and the drying time is preferably 30 seconds to 10 minutes.

The thickness of the adhesive layer formed on the substrate is preferably 0.1 μm or more, more preferably 0.3 μm or more, still more preferably 0.5 μm or more, preferably 3 μm or less, and more preferably 1. It is 5 μm or less, more preferably 1 μm or less. When the thickness of the adhesive layer is at least the lower limit of the above range, the strength of the adhesive layer can be sufficiently secured, and when it is at least the upper limit of the above range, the ion diffusivity of the adhesive layer is ensured. The low temperature output characteristics of the secondary battery can be further improved.

(Non-aqueous secondary battery)
The non-aqueous secondary battery of the present invention is provided with the above-mentioned adhesive layer for a non-aqueous secondary battery, and the battery members are adhered to each other via the adhesive layer for the non-aqueous secondary battery. The non-aqueous secondary battery of the present invention is excellent in low temperature output characteristics.
Specifically, the non-aqueous secondary battery of the present invention includes, for example, a positive electrode, a negative electrode, a separator, and an electrolytic solution, and is provided on or on at least one of the positive electrode, the negative electrode, and the separator. The above-mentioned adhesive layer for a non-aqueous secondary battery is formed between the battery member and the battery container. Then, in an example of the non-aqueous secondary battery of the present invention, the positive electrode and the separator and / or the negative electrode and the separator are adhered and integrated via the adhesive layer for the non-aqueous secondary battery.

In particular, the non-aqueous secondary battery of the present invention is preferably a wound type or a laminated type. When the secondary battery is molded into a wound type or a laminated type, for example, by carrying out a heat pressing process, good adhesiveness is exhibited by the adhesive layer of the present invention, so that good low temperature output characteristics can be obtained. Because it can be obtained.

<Positive electrode and negative electrode>
In the secondary battery of the present invention, as described above, at least one of the positive electrode, the negative electrode, and the separator has an adhesive layer. That is, it is possible to use an electrode in which an adhesive layer is provided on an electrode base material formed by forming an electrode mixture layer on a current collector. As the electrode base material and the separator base material, the same ones as those mentioned in the section of "Adhesive layer for non-aqueous secondary battery" can be used.
Further, the positive electrode and the negative electrode having no adhesive layer are not particularly limited, and an electrode made of the above-mentioned electrode base material can be used.

<Electrolytic solution>
As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. As the supporting electrolyte, for example, a lithium salt is used in a lithium ion secondary battery. Lithium salts include, for example, LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF 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 ) NLi and the like. Of these, LiPF ₆ , LiClO ₄ , and CF ₃ SO ₃ Li are preferable because they are easily soluble in a solvent and show a high degree of dissociation. One type of electrolyte may be used alone, or two or more types may be used in combination. Normally, the more the supporting electrolyte with a higher degree of dissociation is used, the higher the lithium ion conductivity tends to be. Therefore, the lithium ion conductivity can be adjusted depending on the type of the supporting electrolyte.

The organic solvent used in the electrolytic solution is not particularly limited as long as it can dissolve the supporting electrolyte. For example, in a lithium ion secondary battery, dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC) , Propylene carbonate (PC), butylene carbonate (BC), methyl ethyl carbonate (MEC) and other carbonates; esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; sulfolane, Sulfur-containing compounds such as dimethyl sulfoxide; and the like are preferably used. Further, a mixed solution of these solvents may be used. Among them, carbonates are preferable because they have a high dielectric constant and a wide stable potential region. Generally, the lower the viscosity of the solvent used, the higher the lithium ion conductivity tends to be. Therefore, the lithium ion conductivity can be adjusted depending on the type of solvent.
The concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate. Further, a known additive may be added to the electrolytic solution.

<Manufacturing method of non-aqueous secondary battery>
The non-aqueous secondary battery is a battery, for example, in which a positive electrode and a negative electrode are superposed with each other via a separator, and the obtained positive electrode-separator-negative electrode laminate is wound as it is or, if necessary, rolled or folded. It can be manufactured by putting it in a container, injecting an electrolytic solution into a battery container, and sealing it. Here, if necessary, an expanded metal, an overcurrent prevention element such as a fuse or a PTC element, a lead plate, or the like may be placed in the battery container to prevent the pressure inside the battery from rising and overcharge / discharge. The shape of the battery may be, for example, a coin type, a button type, a sheet type, a cylindrical type, a square type, a flat type, or the like.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In the following description, "%" and "part" representing quantities are based on mass unless otherwise specified.
Further, in a polymer produced by copolymerizing a plurality of types of monomers, the ratio of structural units formed by polymerizing a certain monomer in the above-mentioned polymer is usually the same unless otherwise specified. It is consistent with the ratio (preparation ratio) of the certain monomer to all the monomers used for the polymerization of the polymer.
In the examples and comparative examples, the glass transition temperature, the volume average particle diameter D50 of the particulate polymer, the adhesiveness (adhesiveness between the battery members), the blocking resistance of the adhesive layer, and the low temperature output characteristics of the secondary battery are as follows. It was measured and evaluated by the method of.

<Glass transition temperature>
The particulate polymers (1) and (2) produced in Examples and Comparative Examples were used as measurement samples, respectively. Weigh 10 mg of the measurement sample into an aluminum pan, and use an empty aluminum pan as a reference with a differential thermal analysis measuring device (“EXSTAR DSC6220” manufactured by SII Nanotechnology), and measure the temperature range from -100 ° C to 500 ° C. Measurements were performed at a heating rate of 10 ° C./min under the conditions specified in JIS Z 8703 to obtain a differential scanning calorimetry (DSC) curve. In this heating process, the baseline immediately before the heat absorption peak of the DSC curve whose differential signal (DDSC) becomes 0.05 mW / min / mg or more and the tangent line of the DSC curve at the inflection point that first appears after the heat absorption peak. The intersection with was determined as the glass transition temperature (° C.).

<Volume average particle size D50 of particulate polymer>
A laser diffraction type particle size distribution measuring device (Beckman Coulter) for an aqueous dispersion solution adjusted to a solid content concentration of 0.1% by mass for each of the particulate polymers (1) and (2) produced in Examples and Comparative Examples. In the particle size distribution (volume basis) measured by the company, product name "LS-230"), it was determined as the particle size (μm) at which the cumulative volume calculated from the small diameter side is 50%, and was set as the volume average particle size D50. ..

<Adhesion between battery members>
The positive electrode and the separator on which the non-aqueous secondary battery adhesive layer prepared in Examples and Comparative Examples were formed were cut out to a width of 10 mm and a length of 50 mm, respectively. Then, the positive electrode and the separator were laminated to form a laminated body. Then, the laminate was pressed with a roll press having a temperature of 80 ° C. and a load of 10 kN / m to obtain a test piece. This test piece was attached with cellophane tape on the surface of the electrode with the side of the electrode (positive electrode) on the current collector side facing down. At this time, as the cellophane tape, the one specified in JIS Z1522 was used. The cellophane tape was fixed on a horizontal test table. Then, the stress when one end of the separator base material was pulled vertically upward at a tensile speed of 50 mm / min and peeled off was measured. This measurement was performed three times for the laminate provided with the positive electrode and the separator, and the average value of stress was obtained as the peel strength and evaluated according to the following criteria. The larger the peel strength value, the higher the adhesiveness between the battery members.
A: Peel strength is 10 N / m or more B: Peel strength is 5 N / m or more and less than 10 N / m C: Peel strength is less than 5 N / m

<Blocking resistance of adhesive layer>
The separator and the positive electrode on which the adhesive layer for the non-aqueous secondary battery prepared in Examples and Comparative Examples were formed were cut into squares having a width of 5 cm and a length of 5 cm. Two of the obtained square pieces were superposed so that the separators with the adhesive layer and the positive electrodes with the adhesive layer faced each other, and after the superposition, the pressure was applied at 40 ° C. and 10 g / cm ^2. It was placed to prepare a measurement sample. The obtained measurement sample was left to stand for 24 hours, and it was confirmed whether the separators with an adhesive layer and the positive electrodes with an adhesive layer were adhered to each other. In the measurement sample left for 24 hours, the separator forming the adhesive layer for the non-aqueous secondary battery, or when the positive electrodes are adhered to each other, the overlapped separator or the entire square piece of the positive electrode Was fixed, and the other sheet was pulled with a force of 0.3 N / m to confirm whether or not it could be peeled off, and the adhesive state (blocking state) was evaluated according to the following criteria. It indicates that the blocking resistance is so good that no adhesion is observed.
A: The square pieces are not glued together.
B: The square pieces are adhered to each other but peeled off.
C: Square pieces adhere to each other and do not peel off.

<Low temperature output characteristics of secondary batteries>
The laminated laminated lithium ion secondary battery having a capacity of 40 mAh produced in Examples and Comparative Examples was allowed to stand for 24 hours in an environment of 25 ° C. Then, in an environment of 25 ° C., a charging operation was performed at a charging rate of 0.1 C for 5 hours, and the voltage V0 at that time was measured. Then, the discharge operation was performed at a discharge rate of 1C in an environment of −10 ° C., and the voltage V1 15 seconds after the start of discharge was measured.
Then, the voltage change ΔV was calculated by ΔV = V0-V1 and evaluated according to the following criteria. The smaller the value of the voltage change ΔV, the better the low temperature output characteristic of the secondary battery.
A: Voltage change ΔV is less than 350 mV B: Voltage change ΔV is 350 mV or more and less than 500 mV C: Voltage change ΔV is 500 mV or more

(Example 1)
<Preparation of Particulate Polymer (1)>
As the particulate polymer (1), the particulate polymer A1 was prepared.
70 parts of ion-exchanged water and 0.5 part of potassium persulfate were supplied to a reactor equipped with a stirrer, the gas phase part was replaced with nitrogen gas, and the temperature was raised to 60 ° C.
On the other hand, in another container, 50 parts of ion-exchanged water, 0.3 part of sodium dodecylbenzenesulfonate as an emulsifier, 60 parts of methyl methacrylate, 35 parts of butyl acrylate, and 4 parts of methacrylic acid as polymerizable monomers. One part of ethylene glycol dimethacrylate was mixed as a crosslinkable monomer to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours and polymerized at 60 ° C. After completion of the addition, the mixture was heated to 70 ° C. and stirred for 3 hours to complete the reaction, and an aqueous dispersion containing the particulate polymer A1 was prepared. Then, the volume average particle diameter D50 _{(1) of the} particulate polymer A1 and the glass transition temperature were measured. The results are shown in Table 1.

<Preparation of Particulate Polymer (2)>
As the particulate polymer (2), a particulate polymer B1 having a core-shell structure was prepared.
First, in forming the core portion, 42 parts of methyl methacrylate monomer, 24.5 parts of butyl acrylate, 2.8 parts of methacrylic acid monomer, and 0.7 part of ethylene glycol dimethacrylate were placed in a 5 MPa pressure resistant container equipped with a stirrer. , 1 part of sodium dodecylbenzene sulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 part of potassium persulfate as a polymerization initiator were added, and the mixture was sufficiently stirred and then heated to 60 ° C. to initiate polymerization. .. When the polymerization conversion rate reached 96%, 29.7 parts of styrene and 0.3 part of methacrylic acid monomer were continuously added to form a shell part, and the mixture was heated to 70 ° C. to continue polymerization. Then, when the conversion rate reached 96%, the mixture was cooled and the reaction was stopped to produce an aqueous dispersion containing the particulate polymer B1. Then, the volume average particle diameter D50 _{(2) of the} particulate polymer B1 and the glass transition temperature were measured. The results are shown in Table 1.

<Manufacturing of binder for adhesive layer>
In a reactor equipped with a stirrer, 70 parts of ion-exchanged water, 0.15 parts of sodium lauryl sulfate (manufactured by Kao Chemical Co., Ltd., product name "Emar 2F") as an emulsifier, and 0.5 part of ammonium perfluate are added. The gas phase portion was replaced with nitrogen gas, and the temperature was raised to 60 ° C.
On the other hand, in another container, 50 parts of ion-exchanged water, 0.5 part of sodium dodecylbenzenesulfonate as an emulsifier, and 94 parts of butyl acrylate, 2 parts of acrylonitrile, 2 parts of methacrylate, N- as a polymerizable monomer. 1 part of hydroxymethylacrylamide and 1 part of allylglycidyl ether were mixed to obtain a monomer mixture. This monomer mixture was continuously added to the reactor over 4 hours for polymerization. During the addition, the reaction was carried out at 60 ° C. After completion of the addition, the reaction was further completed with stirring at 70 ° C. for 3 hours to produce an aqueous dispersion containing an acrylic polymer as a binder for the adhesive layer. The volume average particle diameter D50 of the obtained acrylic polymer was 0.36 μm.

<Preparation of composition slurry for non-aqueous secondary battery adhesive layer>
75 parts of the particulate polymer (1) and 25 parts by mass of the particulate polymer (2), which are equivalent to the solid content, are mixed in a stirring container, and 22 parts of the adhesive layer binder are further mixed. A composition for a non-aqueous secondary battery adhesive layer was obtained.
Further, 1 part of a surface tension adjusting agent (ethylene oxide-propylene oxide copolymer) is added to 100 parts of the solid content of the particulate polymers (1) and (2), further diluted with ion-exchanged water, and solidified. A composition slurry for a non-aqueous secondary battery adhesive layer having a dilution of 30% was obtained.

<Manufacturing a separator with an adhesive layer for non-aqueous secondary batteries>
The composition slurry for the adhesive layer was applied onto a separator (made of polypropylene, Celguard 2500) substrate and dried at 50 ° C. for 3 minutes. This operation was performed on both sides of the separator base material to obtain a separator having an adhesive layer for a non-aqueous secondary battery having a thickness of 1 μm on each side. For the obtained separator, a test piece was prepared according to the above method, and the blocking resistance and adhesiveness of the adhesive layer were evaluated. The results are shown in Table 1.

<Manufacturing of negative electrode>
In a 5 MPa pressure resistant container with a stirrer, 33 parts of 1,3-butadiene, 3.5 parts of itaconic acid, 63.5 parts of styrene, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and as a polymerization initiator. 0.5 part of potassium persulfate was added, and the mixture was sufficiently stirred and then heated to 50 ° C. to initiate polymerization. When the polymerization conversion rate reached 96%, the mixture was cooled to stop the reaction to obtain a mixture containing particulate negative electrode binder (SBR). A 5% aqueous sodium hydroxide solution was added to the mixture containing the binder for the negative electrode to adjust the pH to 8, and then unreacted monomers were removed by hot vacuum distillation, and then cooled to 30 ° C. or lower. An aqueous dispersion containing a binder for the negative electrode was obtained.
Next, 100 parts of artificial graphite (volume average particle diameter D50: 15.6 μm) as a negative electrode active material and a 2% aqueous solution of carboxymethyl cellulose sodium salt (“MAC350HC” manufactured by Nippon Paper Co., Ltd.) as a thickener are added to the solid content. It was added to 1 part in a considerable amount, adjusted to a solid content concentration of 68% with ion-exchanged water, and then mixed at 25 ° C. for 60 minutes. Further, after adjusting the solid content concentration to 62% with ion-exchanged water, the mixture was further mixed at 25 ° C. for 15 minutes. Next, 1.5 parts of the above negative electrode binder was added to the obtained mixed solution in an amount equivalent to the solid content, and the final solid content concentration was adjusted to 52% with ion-exchanged water for another 10 minutes. Mixed. This was defoamed under reduced pressure to obtain a slurry composition for the negative electrode of a secondary battery.
Then, the slurry composition for the negative electrode obtained above is applied to a copper foil having a thickness of 20 μm, which is a current collector, with a comma coater so that the film thickness after drying is about 150 μm, and dried. It was. This drying was carried out by transporting the copper foil at a rate of 0.5 m / min in an oven at 60 ° C. for 2 minutes. Then, it was heat-treated at 120 degreeC for 2 minutes to obtain the negative electrode raw fabric before pressing. The negative electrode raw material before pressing was rolled by a roll press to obtain a negative electrode after pressing with a thickness of the negative electrode mixture layer of 80 μm (single-sided negative electrode).

<Preparation of positive electrode>
100 parts of LiCoO ₂ (volume average particle size D50: 12 μm) as a positive electrode active material, ₂ parts of acetylene black (“HS-100” manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive material, and a binder for a positive electrode. Two parts of polyvinylidene fluoride (manufactured by Kureha Co., Ltd., # 7208) corresponding to the solid content were mixed, and N-methylpyrrolidone was added to adjust the total solid content concentration to 70% by mass. These were mixed by a planetary mixer to prepare a slurry composition for a positive electrode.
Then, the slurry composition for a positive electrode was applied to an aluminum foil having a thickness of 20 μm, which is a current collector, with a comma coater so that the film thickness after drying was about 150 μm, and dried. This drying was carried out by transporting the copper foil at a rate of 0.5 m / min in an oven at 60 ° C. for 2 minutes. Then, it was heat-treated at 120 degreeC for 2 minutes to obtain the positive electrode raw fabric before pressing. The raw electrode of the positive electrode before pressing was rolled by a roll press to obtain a positive electrode after pressing with a thickness of the positive electrode mixture layer of 80 μm (single-sided positive electrode).

<Manufacturing of lithium-ion secondary batteries>
The positive electrode after pressing obtained above is cut out into a square of 4 cm × 4 cm, and the separator with an adhesive layer for a non-aqueous secondary battery obtained above is cut out and arranged on the surface of the positive electrode mixture layer of the positive electrode in a size of 5 cm × 5 cm. did. Further, the pressed negative electrode prepared as described above was cut into a size of 4.2 cm × 4.2 cm, and this was placed on a separator with an adhesive layer for a non-aqueous secondary battery so that the surfaces on the negative electrode mixture layer side faced each other. It was made into a laminated body. Next, the obtained laminate was pressed at a temperature of 60 ° C. and 0.5 MPa to bond them. Subsequently, the bonded laminate was wrapped with an aluminum packaging material exterior as the battery exterior, and the electrolytic solution (solvent: ethylene carbonate (EC) / diethyl carbonate (DEC) / vinylene carbonate (VC) (volume ratio) = 68.5 / 30 / 1.5, electrolyte: LiPF ₆ ) having a concentration of 1 M was injected so that no air remained. Then, at 150 ° C., the opening of the aluminum packaging material exterior was heat-sealed, and the aluminum packaging material exterior was sealed and closed to manufacture a 40 mAh laminated laminated lithium ion secondary battery.
Then, the low temperature output characteristics of the manufactured lithium ion secondary battery were evaluated. The results are shown in Table 1.

(Example 2)
Particulate polymer A2 was prepared as the particulate polymer (1). In the preparation of the particulate polymer A2, various measurements and evaluations were carried out in the same manner as in Example 1 except that the blending amount of methyl methacrylate was 68 parts and changed to 27 parts of butyl acrylate. The results are shown in Table 1.

(Example 3)
A particulate polymer B2 having a core-shell structure was prepared as the particulate polymer (2). In the preparation of the particulate polymer B2, various measurements were carried out in the same manner as in Example 1 except that the amount of styrene at the time of forming the shell portion was 27.6 parts and 2.1 parts of 2-ethylhexyl acrylate was blended. Evaluation was performed. The results are shown in Table 1.

(Example 4)
Example 1 except that the amount of the particulate polymer (1) was 85 parts and the amount of the particulate polymer (2) was 15 parts when the composition slurry for the non-aqueous secondary battery adhesive layer was prepared. In the same manner as above, various measurements and evaluations were performed. The results are shown in Table 1.

(Example 5)
As the particulate polymer (1), the particulate polymer A3 having a diameter different from that of the particulate polymer A1 is used, and as the particulate polymer (2), the particulate polymer B3 having a diameter different from that of the particulate polymer B1. Were prepared respectively. The same procedure as in Example 1 was carried out except that the blending amount of sodium dodecylbenzenesulfonate, which is an emulsifier, was changed to 0.4 part when the particulate polymer A3 was prepared. Further, the same procedure as in Example 1 was carried out except that the blending amount of sodium dodecylbenzenesulfonate was changed to 0.2 parts and the blending amount of potassium persulfate was changed to 0.2 parts at the time of preparing the particulate polymer B3.
Further, when the composition slurry for the non-aqueous secondary battery adhesive layer was prepared, the amount of the particulate polymer (1) was 85 parts, and the amount of the particulate polymer (2) was 15 parts.
Except for these points, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
Example 1 except that the amount of the particulate polymer (1) was 60 parts and the amount of the particulate polymer (2) was 40 parts when the composition slurry for the non-aqueous secondary battery adhesive layer was prepared. In the same manner as above, various measurements and evaluations were performed. The results are shown in Table 1.

(Example 7)
As the particulate polymer (1), a particulate polymer A4 having a diameter different from that of the particulate polymer A1 was prepared. This was the same as in Example 1 except that the blending amount of sodium dodecylbenzenesulfonate, which is an emulsifier, was changed to 0.2 part at the time of preparing the particulate polymer A4.
Further, at the time of preparing the composition slurry for the non-aqueous secondary battery adhesive layer, the blending amount of the particulate polymer (1) was 60 parts, and the blending amount of the particulate polymer (2) was 40 parts.
Except for these points, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
As the particulate polymer (1), the particulate polymer A5 having a diameter different from that of the particulate polymer A1 is used, and as the particulate polymer (2), the particulate polymer B4 having a diameter different from that of the particulate polymer B1. Were prepared respectively.
Similar to Example 1 except that the amount of the emulsifier sodium dodecylbenzenesulfonate was changed to 0.2 parts and the amount of potassium persulfate was changed to 0.2 parts at the time of preparing the particulate polymer A5. did.
The same as in Example 1 except that the amount of the emulsifier sodium dodecylbenzenesulfonate was changed to 0.2 parts and the amount of potassium persulfate was changed to 0.3 parts when the particulate polymer B4 was prepared. did.
Further, when the composition slurry for the non-aqueous secondary battery adhesive layer was prepared, the amount of the particulate polymer (1) was 80 parts, and the amount of the particulate polymer (2) was 20 parts.
Except for these points, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

(Example 9)
Particulate polymers A1 and B1 were prepared in the same manner as in Example 1 to prepare a composition slurry for a non-aqueous secondary battery adhesive layer. Then, in the production of the lithium ion secondary battery, the separator base material is used as it is as a separator without forming an adhesive layer, and as the negative electrode and the positive electrode, a negative electrode having an adhesive layer and a positive electrode having an adhesive layer are used. A lithium ion secondary battery was manufactured in the same manner as in Example 1. Then, various measurements and evaluations were performed according to the above method. The results are shown in Table 1. The methods for producing the negative electrode provided with the adhesive layer and the positive electrode provided with the adhesive layer are as follows.

<Preparation of negative electrode / positive electrode with adhesive layer>
In the same manner as in Example 1, a negative electrode / positive electrode mixture layer having a thickness of 80 μm is formed on the current collector, and after obtaining an electrode base material, a composition for an adhesive layer is formed on the surface on the negative electrode / negative electrode mixture layer side. The electrode slurry was applied and dried at 50 ° C. for 3 minutes. As a result, a negative electrode / positive electrode having an adhesive layer having a thickness of 1 μm on one side was produced.

(Comparative Example 1)
As the particulate polymer (1), a particulate polymer C1 having a glass transition temperature of more than 80 ° C. was prepared. Particulate weight in the same manner as in Example 1 except that the amount of the methyl methacrylate monomer was changed to 74 parts and the amount of butyl acrylate was changed to 21 parts at the time of preparing the particulate polymer C1. An aqueous dispersion containing the coalesced C1 was produced. Other than that, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
As the particulate polymer (2), a particulate polymer D1 having a core portion with a glass transition temperature of 80 ° C. or higher and a shell portion with a glass transition temperature of less than 80 ° C. was prepared. When preparing the particulate polymer D1, the amount of methyl methacrylate was 52.5 parts, the amount of butyl acrylate was 14 parts, the amount of styrene was 26.4 parts, and the amount of 2-ethylhexyl acrylate was 3.3. An aqueous dispersion containing the particulate polymer D1 was produced in the same manner as in Example 4 except that the parts were partially blended. Other than this, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
As the particulate polymer (1), the particulate polymer C2 having a volume average particle diameter smaller than 0.1 μm is used, and as the particulate polymer (2), the particulate polymer having a diameter different from that of the particulate polymer B1. B5 was prepared respectively.
The same procedure as in Example 1 was carried out except that the amount of the emulsifier sodium dodecylbenzenesulfonate was changed to 3 parts and the amount of potassium persulfate was changed to 1 part at the time of preparing the particulate polymer C2.
The same procedure as in Example 1 was carried out except that the blending amount of sodium dodecylbenzenesulfonate, which is an emulsifier, was changed to 0.6 parts when the particulate polymer B5 was prepared.
Except for these points, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
As the particulate polymer (1), a particulate polymer A6 having a diameter different from that of the particulate polymer A1 is used as a particulate polymer (2), and a particulate polymer having a volume average particle diameter smaller than 0.1 μm. D2 was prepared respectively.
The same procedure as in Example 1 was carried out except that the blending amount of sodium dodecylbenzenesulfonate, which is an emulsifier, was changed to 0.6 parts when the particulate polymer A6 was prepared.
The same procedure as in Example 1 was carried out except that the amount of the emulsifier sodium dodecylbenzenesulfonate was changed to 3 parts and the amount of potassium persulfate was changed to 1 part at the time of preparing the particulate polymer D2.
Except for these points, various measurements and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

From Examples 1 to 9 in Table 1, both are two kinds of particulate polymers having a volume average particle diameter D50 of 0.1 μm or more and 5 μm or less, and have at least one glass transition temperature of less than 80 ° C. The adhesive layer formed from the composition containing the particulate polymer, the particulate polymer having a core-shell structure and the glass transition temperature of the shell portion of 80 ° C. or higher, and the binder has blocking resistance. It turns out to be excellent. In addition, it can be seen that the secondary battery provided with the adhesive layer is excellent in low temperature output characteristics.

According to the present invention, a composition for a non-aqueous secondary battery adhesive layer can be obtained, which can exhibit excellent blocking resistance in the adhesive layer and exhibit excellent low temperature output characteristics in the secondary battery. Be done.
Further, according to the present invention, it is possible to obtain an adhesive layer for a non-aqueous secondary battery which is excellent in blocking resistance and can exhibit excellent low temperature output characteristics in a secondary battery.
Further, according to the present invention, a non-aqueous secondary battery having excellent low temperature output characteristics can be obtained.

Claims (5)

A composition for a non-aqueous secondary battery adhesive layer containing a particulate polymer A, a particulate polymer B, and a binder.
The particulate polymer A has at least one glass transition temperature of less than 80 ° C.
The particulate polymer B has a core-shell structure including a core portion and a shell portion covering the outer surface of the core portion having a glass transition temperature of 80 ° C. or higher.
The volume average particle diameter D50 _{A of the} particulate polymer _A is 0.4 μm or more and 5 μm or less, and the volume average particle diameter D50 _{B of the} particulate polymer _B is 0.1 μm or more and 5 μm or less.
The volume average particle size D50 _B of the particulate polymer _B is 0.5 times or more and 5 times or less the volume average particle size D50 _A of the particulate polymer A, and
The content of the particulate polymer A is, relative to the content of the particulate polymer B, and mass, are two / 3 times 9 times der below,
The binder is, than both the particulate polymer A and the particulate polymer B, the volume average particle size D50 Ru small particulate polymer der,
Composition for non-aqueous secondary battery adhesive layer. The composition for a non-aqueous secondary battery adhesive layer according to claim 1, wherein the binder is a thermoplastic elastomer. An adhesive layer for a non-aqueous secondary battery formed by using the composition for a non-aqueous secondary battery adhesive layer according to claim 1 or 2 . A non-aqueous secondary battery comprising the adhesive layer for the non-aqueous secondary battery according to claim 3 . The non-aqueous secondary battery according to claim 4 , which is a wound type or a laminated type.