JP2015138770A - Laminate, power storage device separator, power storage device, lithium ion secondary battery, and copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a laminate superior in the adhesion between a power storage device separator and an electrode; a power storage device separator; a power storage device; a lithium ion secondary battery; and a copolymer.SOLUTION: A laminate according to the present invention comprises: at least one electrode; a separator base material; and a layer formed at least partially between the separator base material and the at least one electrode, and including a thermoplastic polymer. Further, in the laminate, the thermoplastic polymer includes a copolymer having, as a monomer unit, an ethylenic unsaturated monomer having an amide group.

Description

  The present invention relates to a laminate, an electricity storage device separator, an electricity storage device, a lithium ion secondary battery, and a copolymer.

  In recent years, development of nonaqueous electrolyte batteries centering on lithium ion batteries has been actively conducted. Usually, in a nonaqueous electrolyte battery, a microporous membrane (separator) is provided between positive and negative electrodes. Such a separator has a function of preventing direct contact between the positive and negative electrodes and allowing ions to permeate through the electrolytic solution held in the micropores.

  In order to improve the cycle characteristics and safety of the nonaqueous electrolyte battery, improvement of the separator has been studied. In recent years, as portable devices become smaller and thinner, power storage devices such as lithium ion secondary batteries are also required to be smaller and thinner. On the other hand, in order to be able to carry for a long time, the capacity is increased by improving the volume energy density.

  Conventional separators have a characteristic that the battery reaction is quickly stopped if the separator is abnormally heated (fuse characteristics), preventing the dangerous situation where the cathode and anode materials react directly by maintaining the shape even at high temperatures. Performance related to safety such as performance (short characteristics) is required. In addition to these, recently, separators are also required to have improved adhesion to electrodes from the viewpoints of uniform charge / discharge current and suppression of lithium dendrite.

  By improving the close contact between the separator and the battery electrode, non-uniform charge / discharge current is less likely to occur, and lithium dendrite is less likely to precipitate, resulting in longer charge / discharge cycle life. Become.

  Under such circumstances, as an attempt to give the separator an adhesive property, for example, in Patent Document 1, a porous battery is provided for the purpose of providing a secondary battery excellent in discharge characteristics and safety (heat resistance). An adhesive-carrying porous film for a battery separator obtained by applying a reactive polymer on a membrane and drying it has been proposed. Similarly, Patent Document 2 proposes that an adhesive resin be present by applying a solution containing an adhesive resin to the surface of the polyolefin microporous membrane. In an electricity storage device such as a non-aqueous electrolyte battery, the active material of the positive electrode or the negative electrode repeatedly expands and contracts during charge and discharge, so that the adhesive has excellent adhesion with the electrode active material and at the same time in the electrolytic solution. Excellent cushioning is required.

JP 2007-59271 A JP 2011-54502 A

  However, the separator using the adhesive-carrying porous film described in Patent Document 1 has a problem that the adhesion between the reactive polymer and the porous film is not sufficient, and therefore, the adhesion with the electrode is not sufficient. . In addition, the microporous membranes described in Patent Documents 1 and 2 still have room for improvement from the viewpoint of handling property, adhesiveness, and lithium ion permeability when winding the battery.

  The present invention has been made in view of the above circumstances, and provides a laminate, an electricity storage device separator, an electricity storage device, a lithium ion secondary battery, and a copolymer excellent in adhesion between the electricity storage device separator and the electrode. The purpose is to do.

  As a result of intensive studies to achieve the above object, the inventors of the present invention contain at least one electrode; a separator substrate; and a predetermined polymer in at least a part between the separator substrate and the electrode. The present invention has been completed by finding that the above-described problems can be solved by using a laminate comprising: a layer;

That is, the present invention is as follows.
[1]
At least one electrode;
A separator substrate;
A layer containing a thermoplastic polymer formed at least in part between the separator substrate and the electrode;
A laminate comprising:
The laminated body in which the said thermoplastic polymer contains the copolymer which has an ethylenically unsaturated monomer which has an amide group as a monomer unit.
[2]
The laminate according to [1], wherein the ethylenically unsaturated monomer having an amide group is acrylamide and / or methacrylamide.
[3]
The laminate according to [1] or [2], wherein the content of the ethylenically unsaturated monomer having an amide group in the copolymer is 1 to 15% by mass.
[4]
[1] to [3], wherein the thermoplastic polymer layer containing the copolymer is pressed against an aluminum foil at a temperature of 80 ° C. and a pressure of 10 MPa for 2 minutes, and the peel strength is 4 N / m or more. The laminated body in any one of.
[5]
The laminate according to any one of [1] to [4], wherein the layer containing the thermoplastic polymer is present in a dot shape with respect to a plane perpendicular to the lamination direction.
[6]
The laminate according to any one of [1] to [5], wherein the separator substrate is a polyolefin microporous film.
[7]
An electricity storage device comprising the laminate according to any one of [1] to [6].
[8]
A lithium ion secondary battery comprising the laminate according to any one of [1] to [6].
[9]
A separator for an electricity storage device comprising a separator substrate and a layer containing a thermoplastic polymer in at least a part of at least one surface of the separator substrate,
A copolymer in which the thermoplastic polymer has, as monomer units, an ethylenically unsaturated monomer having an amide group and another monomer copolymerizable with the ethylenically unsaturated monomer having an amide group A separator for an electricity storage device, comprising:
[10]
The electrical storage device separator according to [9], wherein the ethylenically unsaturated monomer having an amide group is acrylamide and / or methacrylamide.
[11]
The separator for an electricity storage device according to [9] or [10], wherein the content of the ethylenically unsaturated monomer having an amide group in the copolymer is 1 to 15% by mass.
[12]
The separator for an electricity storage device according to any one of [9] to [11], wherein the peel strength after pressing the aluminum foil at a temperature of 80 ° C. and a pressure of 10 MPa for 2 minutes is 4 N / m or more.
[13]
The separator for an electricity storage device according to any one of [9] to [12], wherein the layer containing the thermoplastic polymer is present in a dot shape on at least one surface of the separator substrate.
[14]
The electrical storage device separator according to any one of [9] to [13], wherein the separator substrate is a polyolefin microporous film.
[15]
[9] An electricity storage device comprising the electricity storage device separator according to any one of [9] to [14].
[16]
[9] A lithium ion secondary battery comprising the separator for an electricity storage device according to any one of [14].
[17]
A copolymer having, as monomer units, an ethylenically unsaturated monomer having an amide group and another monomer copolymerizable with the ethylenically unsaturated monomer having an amide group.
[18]
The copolymer according to [17], wherein the ethylenically unsaturated monomer having an amide group is acrylamide and / or methacrylamide.
[19]
The copolymer according to [17] or [18], wherein the content of the ethylenically unsaturated monomer having an amide group in the copolymer is 1 to 15% by mass.
[20]
The copolymer according to any one of [17] to [19], wherein the degree of swelling of the copolymer with respect to a mixed solvent of ethylene carbonate and diethyl carbonate (mass ratio 2: 3) is 5.0 times or less.
[21]
The copolymer according to any one of [17] to [20], wherein the copolymer is produced by emulsion polymerization.
[22]
The copolymer according to any one of [17] to [21], wherein the copolymer is used for an electricity storage device.
[23]
The copolymer according to any one of [17] to [21], wherein the copolymer is used for an electricity storage device separator or an electrode.
[24]
An aqueous dispersion comprising water and the copolymer according to any one of [17] to [23] dispersed in the water.
[25]
The water according to [24], wherein in the aqueous dispersion, the dynamic surface tension value with a lifetime of 20 milliseconds or less by a maximum bubble pressure method when the copolymer solid content is 30% is 72 mN / m or less. Dispersion.

  ADVANTAGE OF THE INVENTION According to this invention, the laminated body excellent in the adhesiveness of the separator for electrical storage devices and an electrode, the separator for electrical storage devices, an electrical storage device, a lithium ion secondary battery, and a copolymer can be provided.

(A)-(E) are schematic diagrams which show the planar shape of the thermoplastic polymer layer in the laminated body of this invention.

  Hereinafter, a mode for carrying out the present invention (hereinafter abbreviated as “this embodiment”) will be described in detail. The present invention is not limited to the following embodiment, and can be implemented with various modifications within the scope of the gist. In the present specification, “(meth) acryl” means “acryl” and “methacryl” corresponding thereto, “(meth) acrylate” means “acrylate” and “methacrylate” corresponding thereto, “(Meth) acryloyl” means “acryloyl” and its corresponding “methacryloyl”.

  The laminate of the present embodiment includes: at least one electrode; a separator base; and a layer containing a thermoplastic polymer formed in at least a part between the separator base and the electrode. In the laminate, the thermoplastic polymer includes a copolymer having an ethylenically unsaturated monomer having an amide group as a monomer unit. The copolymer of this embodiment is a copolymer having an ethylenically unsaturated monomer having an amide group as a monomer unit. The separator for an electricity storage device of the present embodiment includes a separator substrate and a layer containing a thermoplastic polymer formed on at least a part of at least one surface of the separator substrate. And a copolymer having an ethylenically unsaturated monomer having an amide group as a monomer unit. Since it is comprised as mentioned above, the laminated body of this embodiment, the separator for electrical storage devices, and a copolymer are excellent in the adhesiveness of the base material for separators, and an electrode. Hereinafter, a layer containing a thermoplastic polymer is also referred to as a “polymer layer”. The “ethylenically unsaturated monomer” means a monomer having one or more ethylenically unsaturated bonds in the molecule.

  The ethylenically unsaturated monomer (A) having an amide group is not particularly limited. For example, acrylamide, methacrylamide, N, N-methylenebisacrylamide, diacetone acrylamide, diacetone methacrylamide, maleic acid amide, Examples include maleimide. These are used singly or in combination of two or more. Of these, acrylamide and methacrylamide are preferable. By using acrylamide and / or methacrylamide, the adhesion between the electrode and the separator tends to be further improved. Further, when a thermoplastic resin layer (polymer layer) is supported on a substrate for electrodes or separators, the thermoplastic resin layers tend to be arranged more regularly in the coating surface. It is possible to achieve uniform adhesion between them, and as a result, the adhesion tends to be further improved.

  In the laminate of this embodiment, the copolymer having the above-mentioned ethylenically unsaturated monomer (A) having an amide group as a monomer unit is a monomer (in order to improve various qualities and physical properties). Other monomers (B) copolymerizable with A) can be included as monomer units. The other monomer (B) represents a monomer different from the monomer (A), and is an ethylenic group having an amide group from the monomer (B) or (b1) to (b8) described later. Those corresponding to saturated monomers are excluded. Although it does not specifically limit as another monomer (B), For example, the ethylenically unsaturated monomer (b1) which has a carboxyl group, the ethylenically unsaturated monomer (b2) which has a hydroxyl group, crosslinkability Monomer (b3), ethylenically unsaturated monomer (b4) having a cycloalkyl group, ethylenically unsaturated monomer (b5) having a cyano group, ethylenically unsaturated monomer having an aromatic group (B6), (meth) acrylic acid ester monomer (b7) and other ethylenically unsaturated monomers (b8). Another monomer (B) is used individually by 1 type or in combination of 2 or more types. Further, the other monomer (B) may belong to two or more of the above monomers at the same time. That is, the other monomer (B) is not limited to the following, for example, ethylene having two or more groups selected from the group consisting of a carboxyl group, a hydroxyl group, a cycloalkyl group, a cyano group, and an aromatic group. A crosslinkable monomer having two or more groups selected from the group consisting of a carboxyl group, a hydroxyl group, a cycloalkyl group, a cyano group, and an aromatic group together with an ethylenically unsaturated bond. It may be a mer.

  From the viewpoint of improving cushioning properties in the swollen state, the other monomer (B) preferably contains an ethylenically unsaturated monomer (b1) having a carboxyl group. Examples of the ethylenically unsaturated monomer (b1) having a carboxyl group include, but are not limited to, acrylic acid, methacrylic acid, itaconic acid half ester, maleic acid half ester, and fumaric acid half ester. Examples thereof include monocarboxylic acid monomers and dicarboxylic acid monomers such as itaconic acid, fumaric acid and maleic acid. These are used singly or in combination of two or more. Among these, from the same viewpoint, acrylic acid, methacrylic acid and itaconic acid are preferable, and acrylic acid and methacrylic acid are more preferable.

  Further, from the viewpoint of improving the polymerization stability of the copolymer, the other monomer (B) preferably contains an ethylenically unsaturated monomer (b2) having a hydroxyl group. Examples of the ethylenically unsaturated monomer (b2) having a hydroxyl group include hydroxyl groups such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, polyethylene glycol acrylate and polyethylene glycol methacrylate (meta ) Acrylates. These are used singly or in combination of two or more. Of these, hydroxyethyl acrylate and hydroxyethyl methacrylate are preferred. By using hydroxyethyl acrylate and / or hydroxyethyl methacrylate, the polymerization stability of the copolymer tends to be improved.

  Moreover, it is preferable that a crosslinkable monomer is included as a component which comprises a copolymer from a viewpoint of making the insoluble content with respect to electrolyte solution suitable amount. Here, the crosslinkable monomer may belong to an ethylenically unsaturated monomer (A) having an amide group, or may be a crosslinkable monomer (B) belonging to another monomer (B). It may be b3). That is, there may be used as the crosslinkable monomer (b3) those belonging to the ethylenically unsaturated monomer (A) having an amide group. The crosslinkable monomer is not particularly limited. For example, a monomer having two or more radical polymerizable double bonds, a single monomer having a functional group that gives a self-crosslinking structure during or after polymerization. Examples include the body. These are used singly or in combination of two or more.

  Examples of the monomer having two or more radical polymerizable double bonds include, but are not limited to, divinylbenzene and polyfunctional (meth) acrylate. Among these, polyfunctional (meth) acrylates are preferable from the viewpoint of better electrolytic solution resistance even in a small amount.

  The polyfunctional (meth) acrylate (b3) may be a bifunctional (meth) acrylate, a trifunctional (meth) acrylate, or a tetrafunctional (meth) acrylate, and is not limited to the following. Acrylate, polyoxyethylene dimethacrylate, polyoxypropylene diacrylate, polyoxypropylene dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, butanediol diacrylate, butanediol dimethacrylate, trimethylolpropane triacrylate, trimethylol Examples thereof include propane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate and the like. These are used singly or in combination of two or more. Of these, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate are preferable from the same viewpoint as described above.

  The monomer having a functional group that gives a self-crosslinking structure during or after polymerization is not limited to the following, for example, an ethylenically unsaturated monomer having an epoxy group, an ethylenic monomer having a methylol group, Examples thereof include an ethylenically unsaturated monomer having an alkoxymethyl group, and an ethylenically unsaturated monomer having a hydrolyzable silyl group. These are used singly or in combination of two or more.

  Examples of the ethylenically unsaturated monomer having an epoxy group include, but are not limited to, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, methyl glycidyl acrylate, and methyl glycidyl methacrylate. These are used singly or in combination of two or more. Of these, glycidyl methacrylate is preferred.

  Examples of the ethylenically unsaturated monomer having a methylol group include, but are not limited to, N-methylol acrylamide, N-methylol methacrylamide, dimethylol acrylamide, dimethylol methacrylamide, and the like. These are used singly or in combination of two or more.

  Examples of the ethylenically unsaturated monomer having an alkoxymethyl group include, but are not limited to, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-butoxymethylacrylamide, and N-butoxymethylmethacrylamide. It is done. These are used singly or in combination of two or more.

  Examples of the ethylenically unsaturated monomer having a hydrolyzable silyl group include, but are not limited to, vinyl silane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, and γ-methacryloxypropyl. Examples include trimethoxysilane and γ-methacryloxypropyltriethoxysilane. These are used singly or in combination of two or more.

  Among the crosslinkable monomers, polyfunctional (meth) acrylates are particularly preferable in that there is little variation in the degree of crosslinking.

  Further, from the viewpoint of improving the adhesion between the electrode and the separator, the other monomer (B) preferably contains an ethylenically unsaturated monomer (b4) having a cycloalkyl group. Although it does not specifically limit as an ethylenically unsaturated monomer (b4) which has a cycloalkyl group, For example, what has a cycloalkyl group and has one ethylenically unsaturated bond is mentioned. More specifically, the monomer (b4) is not limited to the following, but has, for example, a cycloalkyl group such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate ( (Meth) acrylic acid ester monomer etc. are mentioned, More preferably, it is a (meth) acrylic acid ester monomer which consists of a cycloalkyl group and a (meth) acryloyloxy group. 4-8 are preferable, as for the number of the carbon atoms which comprise the alicyclic ring of a cycloalkyl group, 6 and 7 are more preferable, and 6 is especially preferable. Further, the cycloalkyl group may or may not have a substituent. Examples of the substituent include a methyl group, an isopropyl group, and a tertiary butyl group. Among the monomers (b4), cyclohexyl (meth) acrylate is preferable from the viewpoint of good polymerization stability when preparing the copolymer. These are used singly or in combination of two or more.

  Examples of the ethylenically unsaturated monomer (b5) having a cyano group include, but are not limited to, acrylonitrile and methacrylonitrile. Moreover, as an ethylenically unsaturated monomer (b6) which has an aromatic group, although not limited to the following, styrene, vinyl toluene, alpha-methyl styrene, etc. are mentioned, for example. Of these, styrene is preferable. The other ethylenically unsaturated monomer (b8) is not limited to the following, but is a monomer group having a conjugated double bond such as 1,3-butadiene in the molecule, or a vinyl group in the molecule. And the like.

  Moreover, it is preferable that another monomer (B) contains the (meth) acrylic acid ester monomer (b7) from a viewpoint of making the oxidation resistance of the thermoplastic polymer containing this copolymer favorable. The (meth) acrylic acid ester monomer (b7) is a monomer different from the monomers (A), (b1) to (b6) and (b8). Examples of the (meth) acrylic acid ester monomer (b7) include, but are not limited to, (meth) acrylic acid esters having one ethylenically unsaturated bond and a chain alkyl group. More specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) ) Acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, and the like. Further, (meth) acrylate having an aromatic ring such as benzyl (meth) acrylate and phenyl (meth) acrylate (more preferably (meth) acrylate composed of an aromatic ring and a (meth) acryloyloxy group) can be mentioned. In these, the (meth) acrylic acid ester monomer which consists of a chain alkyl group and a (meth) acryloyloxy group from a viewpoint of the adhesive improvement of an electrode (electrode active material) and a separator is preferable. More specifically, methyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, Dodecyl (meth) acrylate and the like are preferable, and n-butyl (meth) acrylate, hexyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are more preferable. These (meth) acrylic acid ester monomers (b7) are used singly or in combination of two or more.

  It is preferable that the content rate of the ethylenically unsaturated monomer (A) which has an amide group in the said copolymer is 1-20 mass% with respect to 100 mass% of copolymers. When the content of the ethylenically unsaturated monomer (A) having an amide group is within this range, the polymerization stability during production of the copolymer is good, and the adhesion between the separator and the electrode (electrode active material) Tend to improve more. In addition, when a thermoplastic polymer is supported and formed by applying and drying a coating liquid containing the copolymer on an electrode or a separator substrate, the pattern is not supported on the separator substrate. Tend to be able to. Moreover, it exists in the tendency which can carry | support the more preferable resin amount on the base material for separators for adhesiveness expression. The upper limit of the content ratio is more preferably 18% by mass, and further preferably 15% by mass. On the other hand, the preferable lower limit of the content is 1% by mass, more preferably 1.2% by mass. In addition, by setting the content ratio of the ethylenically unsaturated monomer (A) having an amide group to 1% by mass or more, the rigidity in the region of 0 ° C. to 80 ° C. of the copolymer does not decrease too much, There exists a tendency for the adhesiveness of an electrode and a separator to be kept favorable.

  Moreover, the content ratio of all (meth) acrylic acid ester monomers in the copolymer is preferably 50 to 99% by mass, more preferably 60 to 99% by mass with respect to 100% by mass of the copolymer. More preferably, it is 70-99 mass%, Still more preferably, it is 80-99 mass%. When the content ratio of all (meth) acrylic acid ester monomers is within the above range, when the thermoplastic resin layer containing the copolymer is used for a non-aqueous electrolyte secondary battery, the oxidation resistance of the thermoplastic polymer Tend to be better. Here, the term “all (meth) acrylic acid ester monomers” refers to all the other monomers (B) having a (meth) acrylic acid ester structure regardless of the presence or absence of a functional group.

  When the other monomer (B) contains an ethylenically unsaturated monomer (b1) having a carboxyl group, the content ratio of the ethylenically unsaturated monomer (b1) having a carboxyl group in the copolymer is: Preferably it is 0.1-5 mass% with respect to 100 mass% of copolymers. When the content ratio of the ethylenically unsaturated monomer (b1) having a carboxyl group is 0.1% by mass or more, the separator tends to improve cushioning properties in a swollen state, and is 5% by mass or less. The polymerization stability tends to be good.

  When the other monomer (B) contains an ethylenically unsaturated monomer (b2) having a hydroxyl group, the content ratio of the ethylenically unsaturated monomer (b2) having a hydroxyl group in the copolymer is: Preferably it is 0.1-10 mass% with respect to 100 mass% of copolymers, More preferably, it is 1-10 mass%. When the content ratio of the ethylenically unsaturated monomer (b2) having a hydroxyl group is within the above range, the polymerization stability in preparing the copolymer tends to be further improved.

  When the copolymer contains a crosslinkable monomer, the content is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass with respect to 100% by mass of the copolymer. More preferably, it is 0.1-3 mass%. When the content of the crosslinkable monomer is 0.01% by mass or more, the electrolytic solution resistance tends to be further improved, and when it is 5% by mass or less, the cushioning property in the swollen state is more effectively reduced. It tends to be suppressed. In addition, when using what belongs to the ethylenically unsaturated monomer (A) which has an amide group as a crosslinkable monomer (b3), preferable content rate (mass%) of an above-mentioned crosslinkable monomer ) Is the total of the above (b3) and the crosslinkable monomer belonging to the ethylenically unsaturated monomer (A) having an amide group.

  When the other monomer (B) contains an ethylenically unsaturated monomer (b4) having a cycloalkyl group, the content of the ethylenically unsaturated monomer (b4) having a cycloalkyl group in the copolymer The ratio is preferably 10 to 90% by mass and more preferably 30 to 90% by mass with respect to 100% by mass of the copolymer.

  The glass transition temperature (hereinafter also referred to as “Tg”) of the copolymer is not particularly limited, but may be −40 to 80 ° C., preferably −35 to 80 ° C., more preferably − It is 30 degreeC-80 degreeC, More preferably, it is -30 degreeC-70 degreeC. When the Tg of the copolymer is in the range of −40 to 80 ° C., the adhesion of the separator to the electrode (electrode active material) is further improved. Moreover, when it is set as a mixture of 5-40 mass% of copolymers whose Tg is -40 degreeC-15 degreeC, and 60-95 mass% of copolymers whose Tg is 40-80 degreeC, an electrode (electrode active material) and a separator This is preferable because the thermoplastic resin layer formed on the electrode or the separator tends to have good handling properties such as dust-proofing property and blocking resistance, while maintaining the adhesion to the substrate.

  Here, the glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC). Specifically, it is determined by the intersection of a straight line obtained by extending the base line on the low temperature side in the DSC curve to the high temperature side and the tangent at the inflection point of the stepped change portion of the glass transition.

  “Glass transition” refers to a change in calorific value associated with a change in the state of the polymer that is a test piece in DSC on the endothermic side. Such a change in heat quantity is observed as a step-like change shape in the DSC curve. The “step change” refers to a portion of the DSC curve until the curve moves away from the previous low-temperature base line to a new high-temperature base line. Note that a combination of a step change and a peak is also included in the step change.

  Further, the “inflection point” indicates a point at which the gradient of the DSC curve of the step-like change portion is maximized. Further, in the step-like change portion, when the upper side is the heat generation side, it can also be expressed as a point where the upward convex curve changes to the downward convex curve. “Peak” indicates a portion of the DSC curve from when the curve leaves the low-temperature side baseline until it returns to the same baseline again. “Baseline” refers to a DSC curve in a temperature region where no transition or reaction occurs in the test piece.

  The degree of swelling of the copolymer used in the laminate of this embodiment with respect to the mixed solvent of ethylene carbonate and diethyl carbonate (mass ratio 2: 3) is preferably 5.0 times or less, and 4.5 times or less. More preferably, it is 4.0 times or less, and further preferably 3.5 times or less. When the degree of swelling is 5.0 times or less, the reliability of the electricity storage device tends to be further increased. In addition, when a thermoplastic polymer layer contains 2 or more types of copolymers, let swelling degree be a weighted average of swelling degree of each copolymer.

  The copolymer is obtained, for example, by a usual emulsion polymerization method. There is no restriction | limiting in particular regarding the method of emulsion polymerization, A conventionally well-known method can be used. For example, in a dispersion system containing the above-mentioned monomer, surfactant, radical polymerization initiator, and other additive components used as necessary in an aqueous medium as a basic composition component, each of the above monomers. A copolymer is obtained by polymerizing the monomer composition. In the polymerization, the composition of the monomer composition to be supplied is made constant throughout the entire polymerization process, or the morphological composition change of the particles of the resin dispersion to be produced is changed sequentially or continuously in the polymerization process. Various methods can be used as necessary, such as a method of giving When the copolymer is obtained by emulsion polymerization, for example, it may be in the form of an aqueous dispersion (latex) containing water and a particulate copolymer dispersed in the water.

  The surfactant is a compound having at least one or more hydrophilic groups and one or more lipophilic groups in one molecule. Examples of the surfactant include non-reactive alkyl sulfate, polyoxyethylene alkyl ether sulfate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, alkyl sulfosuccinate, alkyl diphenyl ether disulfonate, naphthalene sulfone. Anionic interfaces such as acid formalin condensate, polyoxyethylene polycyclic phenyl ether sulfate, polyoxyethylene distyrenated phenyl ether sulfate, fatty acid salt, alkyl phosphate, polyoxyethylene alkylphenyl ether sulfate Activators and non-reactive polyoxyethylene alkyl ethers, polyoxyalkylene alkyl ethers, polyoxyethylene polycyclic phenyl ethers, polyoxyethylene disty Phenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, alkylalkanolamide, polyoxyethylene alkylphenyl ether, etc. Nonionic surfactants. In addition to these, a so-called reactive surfactant in which an ethylenic double bond is introduced into the chemical structural formula of a surfactant having a hydrophilic group and a lipophilic group may be used.

  Examples of the anionic surfactant in the reactive surfactant include an ethylenically unsaturated monomer having a sulfonic acid group, a sulfonate group or a sulfate ester group and a salt thereof, and a sulfonic acid group, or A compound having a group (ammonium sulfonate group or alkali metal sulfonate group) which is an ammonium salt or an alkali metal salt thereof is preferable. Specifically, for example, alkylallylsulfosuccinate (for example, Eleminol (trademark) JS-20 manufactured by Sanyo Chemical Co., Ltd., Latemuru (trademark; manufactured by Kao Corporation), S-120, S-180A, S- 180), polyoxyethylene alkylpropenyl phenyl ether sulfate ester salt (for example, Aqualon (trademark; the same shall apply hereinafter) HS-10 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), α- [1- [ (Allyloxy) methyl] -2- (nonylphenoxy) ethyl] -ω-polyoxyethylene sulfate ester salt (for example, ADEKA Corporation soap (trademark; the same shall apply hereinafter) SE-10N manufactured by ADEKA Corporation), ammonium. = Α-sulfonato-ω-1- (allyloxymethyl) alkyloxypolyoxyethylene (eg, Aquaron KH-10 manufactured by Ichi Kogyo Seiyaku Co., Ltd.), styrene sulfonate (for example, Spinomer (trademark) NaSS manufactured by Tosoh Organic Chemical Co., Ltd.), α- [2-[(allyloxy)- 1- (alkyloxymethyl) ethyl] -ω-polyoxyethylene sulfate ester salt (for example, Adeka Soap SR-10 manufactured by ADEKA Corporation), polyoxyethylene polyoxybutylene (3-methyl-3- Butenyl) ether sulfate (for example, LATEMUL PD-104 manufactured by Kao Corporation) may be mentioned.

  Examples of the nonionic surfactant in the reactive surfactant include α- [1-[(allyloxy) methyl] -2- (nonylphenoxy) ethyl] -ω-hydroxypolyoxyethylene (for example, Adeka Soap NE-20, NE-30, NE-40 manufactured by ADEKA Co., Ltd.), polyoxyethylene alkylpropenyl phenyl ether (for example, Aqualon RN-10, RN-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) RN-30 and RN-50), α- [2-[(allyloxy) -1- (alkyloxymethyl) ethyl] -ω-hydroxypolyoxyethylene (for example, Adeka Soap ER manufactured by ADEKA Corporation) -10)), polyoxyethylene polyoxybutylene (3-methyl-3-butenyl) A Le (for example, Kao Corp. LATEMUL PD-420.) And the like.

  Among the above-mentioned various surfactants, reactive surfactants are preferable, anionic reactive surfactants are more preferable, and reactive surfactants having a sulfonic acid group are more preferable. The surfactant is preferably used in an amount of 0.1 to 5 parts by mass with respect to 100 parts by mass of the monomer composition. Surfactant is used individually by 1 type or in combination of 2 or more types.

  The radical polymerization initiator is one that initiates addition polymerization of monomers by radical decomposition with heat or a reducing substance, and any of inorganic initiators and organic initiators can be used. As the radical polymerization initiator, a water-soluble or oil-soluble polymerization initiator can be used. Examples of the water-soluble polymerization initiator include peroxodisulfates, peroxides, water-soluble azobis compounds, and peroxide-reducing agent redox systems. Examples of the peroxodisulfate include potassium peroxodisulfate (KPS), sodium peroxodisulfate (NPS), and ammonium peroxodisulfate (APS). Examples of the peroxide include hydrogen peroxide, t- Examples thereof include butyl hydroperoxide, t-butyl peroxymaleic acid, succinic acid peroxide, and benzoyl peroxide. Examples of water-soluble azobis compounds include 2,2-azobis (N-hydroxyethylisobutyramide), 2 And 2-azobis (2-amidinopropane) dichloride and 4,4-azobis (4-cyanopentanoic acid). Examples of the redox system of the peroxide-reducing agent include sodium peroxide and sodium peroxide. Sulfooxylate formaldehyde, sodium bisulfite, sodium thiosulfate Um, sodium hydroxymethanesulfinic acid, L- ascorbic acid, and its salts, cuprous salts, and include those that combine one or more reducing agents such as ferrous salts.

  The radical polymerization initiator is preferably used in an amount of 0.05 to 2 parts by mass with respect to 100 parts by mass of the monomer composition. A radical polymerization initiator is used individually by 1 type or in combination of 2 or more types.

  A monomer composition containing an ethylenically unsaturated monomer (A) having an amide group and another monomer (B) is emulsion-polymerized, and polymer particles are dispersed in a solvent (water). In the case of forming the obtained dispersion, the solid content of the obtained dispersion is preferably 10% by mass to 70% by mass. When the solid content is within the above range, the amount of the thermoplastic polymer necessary for adhesion between the electrode (electrode active material) and the separator tends to be controlled in a more optimal range.

  Moreover, it is preferable to adjust the pH of the dispersion to a range of 5 to 12 in order to maintain long-term dispersion stability. The pH adjustment is not limited to the following, but amines such as ammonia, sodium hydroxide, potassium hydroxide, and dimethylaminoethanol are preferably used, and the pH is adjusted with ammonia (water) or sodium hydroxide. Is more preferable.

  The aqueous dispersion of this embodiment includes a copolymer obtained by copolymerizing the monomer composition containing the specific monomer as particles (copolymer particles) dispersed in water. In addition to water and the copolymer, the aqueous dispersion may contain a solvent such as methanol, ethanol, isopropyl alcohol, a dispersant, a lubricant, a thickener, a bactericide, and the like.

  The average particle size of the copolymer particles is preferably 100 to 350 nm, more preferably 120 to 350 nm, and still more preferably 130 to 350 nm. Setting the average particle size of the copolymer particles to 100 nm or more is preferable because the air permeability between the positive electrode and the negative electrode can be maintained better. Moreover, it is preferable from the viewpoint of ensuring the dispersion stability of the aqueous dispersion that the average particle diameter of the copolymer particles is 350 nm or less. The average particle diameter of the copolymer particles can be measured according to the method described in the following examples.

  In addition, it can confirm from the infrared absorption spectrum by microscopic IR etc. that a copolymer has an ethylenically unsaturated monomer (A) which has an amide group as a monomer unit. More specifically, copolymers having different contents of the ethylenically unsaturated monomer (A) having an amide group are prepared, and an infrared absorption spectrum of a dry film of the copolymer is obtained. From the respective spectra of the copolymers having different contents of the ethylenically unsaturated monomer (A) having an amide group, the ratio of the peak height derived from the ester and the peak height derived from the amide is determined. A calibration curve is prepared by creating a relationship diagram between the charged molar ratio of the amide group and the ester group and the ratio of the peak derived from the amide group and the peak derived from the ester group read from the IR spectrum. Next, an IR spectrum of the thermoplastic resin containing the copolymer is obtained, and whether or not the amide group-containing monomer is used can be determined based on the presence or absence of the peak derived from the amide group. Further, from the ratio of the peak height derived from the amide group and the peak height derived from the ester group, the presence ratio in the copolymer of the ethylenically unsaturated monomer (A) having an amide group is determined using the above-mentioned calibration curve. Can be obtained.

The laminate of this embodiment is a laminate comprising at least one kind of electrode and a layer containing a thermoplastic polymer formed at least in part between the separator substrate and the electrode. For example, the electrode and the separator can be bonded together through, for example, a hot pressing process. That is, the polymer layer can function as an adhesive layer.
Moreover, when the thing which has a polymer layer in at least one part of the base material as a separator for electrical storage devices of this embodiment is used, the electrode and the separator can be adhere | attached through the process of a hot press. That is, the polymer layer can function as an adhesive layer.
The thermoplastic polymer preferably contains 60 to 90% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more with respect to the total amount of the copolymer. . In addition to the copolymer, the thermoplastic polymer may contain other components to the extent that the solution to the problem of the present invention is not impaired.

  A separator substrate having a fine porous structure can be applied to the separator used in the present embodiment, and the separator itself may be one that has been conventionally used as a separator. The separator base material having a fine porous structure is preferably a porous film having a fine pore diameter, which has no electron conductivity, has ionic conductivity, and is highly resistant to organic solvents. As such a porous membrane, for example, a polyolefin-based (for example, polyethylene, polypropylene, polybutene and polyvinyl chloride), and a microporous membrane containing a resin such as a mixture or copolymer thereof as a main component, polyethylene terephthalate, Microporous membrane containing resin such as polycycloolefin, polyethersulfone, polyamide, polyimide, polyimideamide, polyaramid, polycycloolefin, nylon, polytetrafluoroethylene, woven polyolefin fiber (woven fabric) ), Polyolefin fiber nonwoven fabric, paper, and aggregates of insulating substance particles. Among these, when a polymer layer is obtained through a coating process, the coating liquid is excellent in coating property, the thickness of the separator base material is made thinner, and the active material ratio in an electricity storage device such as a battery is increased. From the viewpoint of increasing the capacity per volume, a polyolefin microporous membrane containing a polyolefin-based resin as a main component is preferable. Here, “include as a main component” means to contain more than 50% by mass, preferably 75% by mass or more, more preferably 85% by mass or more, and further preferably 90% by mass or more. More preferably 95% by mass or more, particularly preferably 98% by mass or more, and may be 100% by mass.

  The thickness of the separator substrate is preferably 0.5 to 40 μm, more preferably 1 to 30 μm, and still more preferably 1 to 10 μm. When the thickness of the separator base material is within this range, the resistance due to the separator base material in a power storage device such as a battery becomes smaller, and when the polymer layer is obtained through a coating process, the separator Workability at the time of coating on the base material for use is further improved.

  In the present embodiment, examples of the polyolefin-based resin used as the material for the separator substrate include homopolymers such as polyethylene and polypropylene, copolymers, and mixtures thereof. Examples of the polyethylene include low density, medium density, and high density polyethylene, and high density polyethylene is preferable from the viewpoint of piercing strength and mechanical strength. These polyethylenes may be used in combination of two or more for the purpose of imparting flexibility. The polymerization catalyst used in the production of these polyethylenes is not particularly limited, and examples thereof include Ziegler-Natta catalysts, Philips catalysts, and metallocene catalysts. From the viewpoint of achieving both high mechanical strength and high permeability, the viscosity average molecular weight of polyethylene is preferably 100,000 or more and 12 million or less, more preferably 200,000 or more and 3 million or less.

The viscosity average molecular weight (Mv) is calculated from the intrinsic viscosity [η] measured at a measurement temperature of 135 ° C. using decalin as a solvent based on ASTM-D4020 by the following formula.
Polyethylene: [η] = 6.77 × 10 ⁻⁴ Mv ^0.67 (Chiang formula)
Polypropylene: [η] = 1.10 × 10 ⁻⁴ Mv ^0.80

  Examples of polypropylene include homopolymers, random copolymers, and block copolymers, and one kind or a mixture of two or more kinds can be used. The polymerization catalyst is not particularly limited, and examples thereof include Ziegler-Natta catalysts and metallocene catalysts. Moreover, there is no restriction | limiting in particular also in the stereoregularity of a polypropylene, Any of isotactic, syndiotactic, and atactic may be sufficient. However, it is preferable to use isotactic polypropylene because it is inexpensive. Furthermore, an appropriate amount of a polyolefin other than polyethylene and polypropylene, and an additive such as an antioxidant and a nucleating agent may be added to the separator substrate within a range not impairing the effects of the present invention.

  A method for producing a separator substrate containing a polyolefin-based resin as a main component may be a known one. Examples of the manufacturing method include a dry manufacturing method and a wet manufacturing method. In the dry production method, for example, a film is first formed by melt extrusion of a polyolefin-based resin such as polypropylene or polyethylene. Thereafter, the film is annealed at a low temperature to grow a crystal domain, and in this state, the film is stretched to extend the amorphous region, thereby forming a microporous film as a separator substrate. In the wet manufacturing method, for example, first, a hydrocarbon solvent or other low molecular weight material and a polyolefin-based resin such as polypropylene or polyethylene are mixed, and then formed into a film shape. Next, the film in which the solvent and low-molecular material have gathered in the amorphous phase and started to form the island phase is removed using another solvent that easily volatilizes the solvent and low-molecular material, so that it can be used as a separator substrate. A microporous film is formed.

  A known method may be used for producing a nonwoven fabric or paper as a separator substrate. The production method includes, for example, a chemical bond method in which a web is dipped in a binder and dried to bond fibers; a thermal bond method in which hot-melt fibers are mixed into the web and the fibers are partially melted to bond fibers. A needle punch method in which a needle having a stab is repeatedly stabbed into the web and mechanically entangled with the fiber; a high-pressure water flow is entangled between the fibers by jetting a high-pressure water stream from the nozzle through the net (screen).

  The separator substrate used in the present embodiment may contain a filler (inorganic filler or organic filler) or a fiber compound for the purpose of controlling strength, hardness, and thermal shrinkage. In addition, when the separator substrate is a laminate of porous membrane layers containing non-conductive particles and a binder, the adhesion is improved by improving the adhesion or reducing the surface tension with the electrolyte. In order to improve the quality of the separator, the surface of the separator substrate is coated with a low molecular weight compound or a high molecular compound in advance, or the separator substrate surface is subjected to electromagnetic radiation treatment such as ultraviolet rays or plasma treatment such as corona discharge / plasma gas. May be. In particular, it contains polar groups such as a carboxylic acid group, a hydroxyl group, and a sulfonic acid group from the viewpoint that the impregnation property of the electrolytic solution is high and the adhesion to the porous membrane layer containing the non-conductive particles and the binder is easily obtained. It is preferable to coat with a polymer compound.

  The separator substrate used in the present embodiment may have a multilayer structure in which the above-described separator substrates are stacked for the purpose of increasing the tear strength and puncture strength. Specific examples include a laminate of a polyethylene microporous membrane and a polypropylene microporous membrane, and a laminate of a nonwoven fabric and a polyolefin microporous membrane.

  The air permeability of the separator base material is not particularly limited, but is preferably 10 sec / 100 cc or more, more preferably 50 sec / 100 cc or more, preferably 1000 sec / 100 cc or less, more preferably, from the viewpoint of improving the performance of the electricity storage device. Is 500 sec / 100 cc or less. The air permeability is preferably 10 sec / 100 cc or more from the viewpoint of further suppressing self-discharge of the electricity storage device. On the other hand, setting it to 1000 sec / 100 cc or less is preferable from the viewpoint of obtaining even better charge / discharge characteristics.

  From the same viewpoint, the porosity of the separator base material is preferably 20% or more, more preferably 35% or more, and preferably 90% from the viewpoint of improving the performance of the electricity storage device and improving the mechanical strength. Hereinafter, it is preferably 80% or less. Setting the porosity to 20% or more is preferable from the viewpoint of securing excellent permeability of the separator. On the other hand, it is preferable to set it as 90% or less from a viewpoint of ensuring the outstanding puncture strength.

  Further, the puncture strength of the separator base material is preferably 200 g / 20 μm or more, more preferably 300 g / 20 μm or more, preferably 2000 g / 20 μm, from the viewpoint of improving reliability as a separator and suppressing heat shrinkage. Hereinafter, it is more preferably 1000 g / 20 μm or less. It is preferable that the puncture strength is 200 g / 20 μm or more from the viewpoint of further suppressing film breakage due to the dropped active material or the like during battery winding. Moreover, it is also preferable from the viewpoint of further suppressing the fear of short-circuiting due to the expansion and contraction of the electrode accompanying charging and discharging. On the other hand, it is preferable to set it as 2000 g / 20 micrometers or less from a viewpoint which can reduce the width | variety shrinkage by the orientation relaxation at the time of a heating.

  These air permeability, porosity, and puncture strength are measured according to the methods described in Examples.

(Amount of polymer layer supported on electrode or separator substrate)
Supported amount to the polymer layer of the electrode (the electrode active material) or separator substrate in the present embodiment is preferably from 0.05 g / m ² or more 1.0 g / m ² or less in terms of solid content, more preferably 0.07 g / m ² or more and 0.80 g / m ² or less, more preferably 0.1 g / m ² or more and 0.70 g / m ² or less. If the loading amount for the electrode layer (electrode active material) or separator base material and 0.05 g / m ² or more 1.0 g / m ² or less, in the obtained laminate, the electrode (the electrode active material) separator It is preferable from the viewpoint of further improving the cycle characteristics (permeability) due to blocking of the pores of the separator base material.

  The amount of the polymer layer supported on the electrode (electrode active material) or the separator substrate can be adjusted, for example, by changing the concentration of the thermoplastic polymer or copolymer in the coating solution or the coating amount of the thermoplastic polymer solution. . However, the method for adjusting the carrying amount is not limited to the above.

(Area ratio of polymer layer between the electrode and separator substrate)
In the present embodiment, the thermoplastic polymer layer is preferably present between the layers at an area ratio of 70% or less with respect to the interlayer area between the electrode (electrode active material) and the separator substrate, and more preferably 50% or less. More preferably, it is 45% or less, particularly preferably 40% or less. The polymer layer is preferably present between the electrode (electrode active material) and the separator substrate at an area ratio of 5% or more. Setting the area ratio of the polymer layer to 70% or less further suppresses blockage of the pores of the separator substrate by the thermoplastic polymer (for example, the copolymer), and further improves the permeability as a separator. To preferred. On the other hand, setting the area ratio to 5% or more is preferable from the viewpoint of further improving the adhesion between the electrode (electrode active material) and the separator.

  The area ratio of the polymer layer in the present embodiment is, for example, the thermoplastic polymer or copolymer concentration in the coating liquid applied to the separator substrate, the coating amount of the coating liquid, the coating method, It can be adjusted by changing the coating conditions. However, the adjustment method of an area ratio is not limited to them. Moreover, the area ratio of the polymer layer in this embodiment is measured according to the method as described in the following Example.

(Average thickness of polymer layer)
The average thickness of the polymer layer between the electrode (electrode active material) and the separator base material in the laminate of the present embodiment is not particularly limited, but is preferably 2.0 μm or less, more preferably 1 0.0 μm or less, more preferably 0.5 μm or less. When the average thickness of the polymer layer is 2.0 μm or less, it is not only preferable from the viewpoint of effectively suppressing a decrease in permeability due to the polymer layer, but also provided as a separator in which a thermoplastic resin is coated on a separator substrate. In the case, it is preferable from the viewpoint of effectively suppressing sticking between the polymer layers or between the polymer layer and the separator substrate when the separator is stored as a roll. The average thickness of the polymer layer in this embodiment is adjusted, for example, by changing the thermoplastic polymer or copolymer concentration in the coating liquid applied to the separator substrate, the coating amount of the coating liquid, the coating method, and the coating conditions. can do. However, the adjustment method of the average thickness of a polymer layer is not limited to them.

(Existence form of thermoplastic polymer layer in laminate)
The presence form (pattern) of the polymer layer in the present embodiment is not particularly limited, and may have a planar shape, for example, shown in black in FIG. 1 with respect to a surface perpendicular to the stacking direction of the stacked body. That is, the polymer layer has, for example, a dot shape (for example, FIG. 1A), a lattice shape (for example, FIG. 1B), a linear shape (for example, FIG. 1C), a stripe shape (for example, FIG. 1 (D)), a tortoiseshell pattern (for example, (E) in FIG. 1), and the like may exist.

  Among these, the polymer layer is preferably present in the form of dots between the electrode and the separator substrate from the viewpoint of ensuring permeability and further improving the uniform adhesion between the electrode and the separator. . “Dot-like” indicates a state of a sea-island structure in which a polymer layer exists in an island shape between the layers, and a portion where the polymer layer does not exist is a sea shape. Although the polymer layer may exist independently in the form of islands, a part thereof may form a continuous surface, but the polymer layer is continuous in most parts, and most of the interlayer area is The case where it is covered with a polymer layer (when the sea of the sea-island structure is a polymer layer) is not included.

  When the polymer layer is present independently in the form of islands, the distance between the island-shaped dots (the distance between the ends of adjacent island-shaped dots) is 5 μm to 500 μm. It is preferable from the viewpoint of compatibility with characteristics. The size of the dot (the longest diameter of one dot; the longest diameter) is not particularly limited, but is preferably 20 μm or more and 1000 μm or less on average, more preferably 30 μm or more and 800 μm or less, and further preferably 50 μm or more and 500 μm or less. is there. Setting the average major axis of the dots of the polymer layer to 20 μm or more and 1000 μm or less is preferable from the viewpoint of securing the adhesion between the electrode and the separator.

  The average major axis of the dots of the polymer layer can be adjusted, for example, by changing the copolymer or thermoplastic polymer concentration of the coating liquid, the coating amount of the coating liquid, the coating method, and the coating conditions. However, the method of adjusting the average major axis of the dots of the polymer layer is not limited to them.

  The separator in this embodiment has a short temperature which is an index of heat resistance, preferably 150 ° C. or higher, and more preferably 160 ° C. or higher. Setting the short circuit temperature to 150 ° C. or higher is preferable from the viewpoint of the safety of the electricity storage device. The short temperature is measured by the method described in Japanese Patent No. 4733232.

  Moreover, it is preferable that the adhesiveness of the electrode of the laminated body and separator in this embodiment is 50% or more in the adhesiveness test measured by the below-mentioned method.

(Laminate manufacturing method)
In the present embodiment, a method of carrying and forming a thermoplastic polymer containing the copolymer of the present embodiment described above on at least one surface of an electrode and a separator base material (hereinafter also referred to as “electrode and base material”). Is not particularly limited. For example, there is a method in which a coating liquid containing a thermoplastic polymer is applied to at least one surface such as an electrode and a substrate, and then the solvent or dispersion medium of the coating liquid is removed as necessary.

  The solvent or dispersion medium contained in the coating solution is not particularly limited, but water is preferable. When applying the coating liquid to the electrode and the substrate, if the coating liquid gets into the electrode and the base material, the thermoplastic polymer containing the copolymer is formed on the surface of the hole of the electrode and the base material. And the inside is closed, and the permeability tends to be lowered. In this regard, when water is used as the solvent or dispersion medium of the coating solution, it becomes difficult for the coating solution to enter the electrodes and the base material, and the thermoplastic polymer including the copolymer is mainly used for the electrode and the base material. Since it becomes easy to exist on an outer surface, since the fall of permeability can be controlled more effectively, it is preferred. Examples of the solvent or dispersion medium that can be used in combination with water include ethanol and methanol.

  There are no particular limitations on the method of applying the coating solution to the electrode and the substrate, as long as the required layer thickness and coating area can be realized. For example, gravure coater method, small-diameter gravure coater method, reverse roll coater method Transfer roll coater method, kiss coater method, dip coater method, knife coater method, air doctor coater method, blade coater method, rod coater method, squeeze coater method, cast coater method, die coater method, screen printing method, spray coating method Can be mentioned.

  In the present embodiment, prior to the application of the coating liquid, surface treatment may be performed on the surfaces of the electrodes and the substrate as necessary. This is preferable because the coating liquid can be more easily applied and the adhesion between the electrode and the separator is improved. The surface treatment method is not particularly limited as long as it does not significantly impair the structure of the electrode and the substrate (for example, the porous structure of the polyolefin microporous membrane). For example, the corona discharge treatment method, plasma treatment method, mechanical Examples include a roughening method, a solvent treatment method, an acid treatment method, and an ultraviolet oxidation method.

  In the present embodiment, when the solvent is removed from the coating solution applied to the electrode and the substrate, there is no particular limitation as long as the method does not adversely affect the electrode and the substrate. For example, when a polyolefin microporous membrane is used as a separator substrate, the separator substrate is fixed at a temperature lower than its melting point, fixed at a low temperature, dried at a low temperature, or immersed in a poor solvent for the copolymer. And a method of coagulating the copolymer and extracting the solvent at the same time. The same can be applied to the electrodes.

  Also, when the copolymer contains copolymer particles and the separator substrate is a polyolefin microporous membrane, the purpose is to improve the adhesion between the copolymer particles and the polyolefin microporous membrane as the separator substrate Thus, copolymer particles having a glass transition temperature (Tg) of 15 ° C. or lower can be mixed and used. The copolymer particles having a Tg of 15 ° C. or less are preferably contained in an amount of 5 to 40% by mass with respect to the total amount of the copolymer particles. The degree of swelling of the copolymer having a Tg of 15 ° C. or lower is not particularly limited, but is preferably 5.0 times or less from the viewpoint of more effectively expressing the adhesiveness.

[Laminate]
Since it can be said that the laminated body of this embodiment has a structure which provided the polymer layer in at least one part between an electrode and the base material for separators, it is excellent also in the adhesiveness of an electrode and a separator, and the permeability | transmittance. The method for producing the laminate is not particularly limited, and may be laminated after the thermoplastic polymer is supported on the electrode side, or may be laminated after being formed on the separator substrate side, or the electrode. Alternatively, they may be laminated after being carried on both the separator base material. Moreover, you may laminate | stack by separately installing a thermoplastic resin film between an electrode and the base material for separators.

  The thermoplastic polymer used between the electrode of the laminate of this embodiment and the separator base material preferably has a peel strength of 4 mN / mm or more with respect to the aluminum foil. This means that it is possible to easily confirm that the thermoplastic polymer used in the laminate of this embodiment has adhesiveness without producing an electrode. The peel strength is measured as follows. That is, an aluminum foil (made by Fuji Paper Co., Ltd., thickness: 20 μm) that is also used as a positive electrode current collector is cut into 20 mm × 100 mm. Next, the thermoplastic polymer of the present embodiment is formed on a separator, and a laminate is obtained by superimposing the polymer layer side surface and an aluminum foil, and then the laminate is made of a Teflon (registered trademark) sheet (Nichias Corporation). The product is sandwiched between Naflon (trademark) PTFE sheet TOMBO-No. 9000) and pressed at 80 ° C. and a pressure of 10 MPa in the laminating direction for 2 minutes. In the sample thus obtained, the peel strength between the aluminum foil and the separator was measured at a tensile speed of 50 mm / min using force gauge ZP5N and MX2-500N manufactured by Imada Corporation.

[Power storage device]
The electrical storage device of this embodiment is provided with the laminated body of this embodiment, and the structure of other than that may be the same as what is known conventionally. The power storage device is not particularly limited, and examples thereof include batteries such as non-aqueous electrolyte secondary batteries, capacitors, capacitors, and the like. Among these, from the viewpoint of more effectively obtaining the benefits of the effects of the present invention, a battery is preferable, a non-aqueous electrolyte secondary battery is more preferable, and a lithium ion secondary battery is still more preferable. Hereinafter, a suitable aspect in the case where the electricity storage device is a non-aqueous electrolyte secondary battery will be described.

  The non-aqueous electrolyte secondary battery including the laminate according to this embodiment includes a non-aqueous electrolyte in addition to the laminate. The electrodes (positive electrode, negative electrode) and separator constituting the laminate and the non-aqueous electrolyte are not particularly limited, and known ones can be used.

Examples of the positive electrode material (positive electrode active material) include lithium-containing composite oxides such as LiCoO ₂ , LiNiO ₂ , spinel type LiMnO ₄ , and olivine type LiFePO ₄ . Examples of the negative electrode material include carbon materials such as graphite, non-graphitizable carbonaceous, graphitizable carbonaceous, and composite carbon bodies; silicon, tin, metallic lithium, and various alloy materials. Each of the positive electrode and the negative electrode may include a current collector. Examples of the positive electrode current collector include an aluminum foil, and examples of the negative electrode current collector include a copper foil.

As the non-aqueous electrolyte, an electrolyte obtained by dissolving an electrolyte in an organic solvent can be used. Examples of the organic solvent include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Examples of the electrolyte include lithium salts such as LiClO ₄ , LiBF ₄ , and LiPF ₆ .

The electricity storage device of this embodiment is manufactured as follows, for example. That is, a separator having a thermoplastic polymer supported on at least one side of a separator is prepared and molded into a vertically long shape having a width of 10 to 500 mm (preferably 80 to 500 mm) and a length of 200 to 4000 m (preferably 1000 to 4000 m). . Next, the separator is stacked together with the positive electrode and the negative electrode in the order of positive electrode-separator negative electrode-separator or negative electrode-separator positive electrode-separator to obtain a laminate. Next, the laminate is wound into a cylindrical or flat spiral shape to obtain a wound body. And the electrical storage device is obtained by accommodating the said wound body in a battery can, and also inject | pouring electrolyte solution. Further, the electricity storage device of this embodiment is laminated in the order of positive electrode-separator negative electrode-separator positive electrode or negative electrode-separator positive electrode-separator negative electrode to obtain a laminate, and then accommodated in a bag-like film. It can also be manufactured through a process of laminating and injecting an electrolyte there.
In producing the laminate, the thermoplastic polymer can be supported on the positive electrode (positive electrode active material) or the negative electrode (negative electrode active material) and then produced through the same steps.

  The various parameters described above are values measured according to the measurement methods in the examples described later unless otherwise specified.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to an Example. The measurement methods and evaluation methods for various physical properties used in the following synthesis examples, production examples, examples and comparative examples are as follows.

[Measuring method]
(1) Solid content About 1 g of the obtained aqueous dispersion of the copolymer was precisely weighed on an aluminum dish, and the mass of the aqueous dispersion weighed at this time was defined as (a) g. It was dried for 1 hour with a hot air dryer at 130 ° C., and the dry mass of the dried copolymer was (b) g. The solid content was calculated by the following formula.
Solid content = (b) / (a) × 100 [%]

(2) Average particle size of copolymer particles Using a light scattering method particle size measuring device (LEED & NORTHHRUP, trade name “MICROTRAC UPA150”), 50% particle size (nm) was measured to obtain an average particle size. .

(3) Weight of base material (polyolefin microporous film) A 10 cm × 10 cm square sample was cut from the base material, and mass was measured using an electronic balance AEL-200 (trade name) manufactured by Shimadzu Corporation. Is multiplied by the resulting mass 100 was calculated 1 m ² per layer of basis weight (g / m ²⁾ in.

(4) Porosity of Substrate (Polyolefin Microporous Membrane) A 10 cm × 10 cm square sample was cut from the substrate, its volume (cm ³ ) and mass (g) were determined, and the membrane density was 0.95 (g / cm ³ ) Calculated using the following formula.
Porosity = (1−mass / volume / 0.95) × 100

(5) Air Permeability of Substrate (Polyolefin Microporous Membrane) Air permeation resistance measured by Gurley type air permeability meter, G-B2 (trademark) manufactured by Toyo Seiki Co., Ltd. according to JIS P-8117 Was the air permeability.

(6) Puncture strength of substrate (polyolefin microporous membrane) Using a handy compression tester KES-G5 (trademark) manufactured by Kato Tech, the substrate was fixed with a sample holder having a diameter of 11.3 mm. Next, by performing a piercing test in a 25 ° C. atmosphere at a piercing speed of 2 mm / sec using a needle having a radius of curvature of 0.5 mm at the center of the fixed substrate. The puncture strength (g) was obtained as the maximum puncture load.

(7) Average pore size of substrate (polyolefin microporous membrane) It is known that the fluid inside the capillary follows the Knudsen flow when the fluid mean free path is larger than the capillary pore size, and the Poiseuille flow when it is small. Yes. Therefore, it was assumed that the air flow in the air permeability measurement of the base material follows the Knudsen flow, and the water flow in the base material permeability measurement follows the Poiseuille flow.

The average pore diameter d (μm) is the air permeation rate constant R _gas (m ³ / (m ² · sec · Pa)), the water permeation rate constant R _liq (m ³ / (m ² · sec · Pa)), From the air molecular velocity ν (m / sec), water viscosity η (Pa · sec), standard pressure P _s (= 101325 Pa), porosity ε (%), and film thickness L (μm), the following equation is used. Asked.
d = 2ν × (R _liq / R _gas ) × (16η / 3Ps) × 10 ⁶
Here, R _gas was calculated | required from the air permeability (second) using the following formula.
R _gas = 0.0001 / (air permeability × (6.424 × 10 ⁻⁴ ) × (0.01276 × 101325))
R _liq was determined from the water permeability (cm ³ / (cm ² · sec · Pa)) using the following formula.
R _liq = water permeability / 100

The water permeability was determined as follows. A base material previously immersed in ethanol is set in a stainless steel liquid-permeable cell having a diameter of 41 mm, and after the ethanol of the base material is washed with water, water is permeated through the base material with a differential pressure of about 50000 Pa, From the water permeability (cm ³ ) when 120 seconds passed, the water permeability per unit time, unit pressure, and unit area was calculated and used as the water permeability.

Ν is a gas constant R (= 8.314), an absolute temperature T (K), a circumference π, and an average molecular weight M of air (= 2.896 × 10 ⁻² kg / mol), using the following formula. Asked.
ν = ((8R × T) / (π × M)) ^1/2

(8) Average thickness of polymer layer The average thickness of the polymer layer was measured by observing the cross section of the separator using a scanning electron microscope (SEM) “Model S-4800, manufactured by HITACHI”. More specifically, the separator was cut out to about 1.5 mm × 2.0 mm and dyed with ruthenium. The stained sample and ethanol were placed in a gelatin capsule, frozen with liquid nitrogen, and then cleaved with a hammer. Next, the sample was subjected to osmium vapor deposition and observed at an acceleration voltage of 1.0 kV and 30000 times, and the average thickness of the polymer layer was calculated. The outermost surface area where the porous structure of the cross section of the substrate (polyolefin microporous film) was not visible in the SEM image was defined as the polymer layer area.

(9) Glass transition temperature of copolymer An appropriate amount of an aqueous dispersion (solid content = 38 to 42% by mass, pH = 9.0) containing a copolymer is placed in an aluminum dish and heated with a hot air dryer at 130 ° C. Dried for minutes. About 17 mg of the dried film after drying was packed in an aluminum container for measurement, and a DSC curve and a DDSC curve in a nitrogen atmosphere were obtained with a DSC measuring apparatus (manufactured by Shimadzu Corporation, model number: DSC6220). The measurement conditions were as follows.
(First stage temperature rise program)
Starting at 70 ° C., the temperature was increased at a rate of 15 ° C. per minute. After reaching 110 ° C., the temperature was maintained for 5 minutes.
(Second stage temperature drop program)
The temperature was lowered from 110 ° C. at a rate of 30 ° C. per minute. After reaching −100 ° C., the temperature was maintained for 4 minutes.
(Third-stage temperature rising program)
The temperature was raised from −100 ° C. to 130 ° C. at a rate of 15 ° C. per minute. DSC and DDSC data were acquired during the third stage of temperature increase.
The intersection of the straight line obtained by extending the base line in the obtained DSC curve to the high temperature side and the tangent at the inflection point was defined as the glass transition temperature (Tg).

(10) Swelling degree of copolymer with respect to electrolyte solution The aqueous dispersion containing the copolymer was allowed to stand in an oven at 130 ° C. for 1 hour and dried. The copolymer film obtained by drying was cut to 0.5 g. The cut sample is put in a 50 mL vial together with 10 g of a mixed solvent of ethylene carbonate: diethyl carbonate = 2: 3 (mass ratio), and the mixed solvent is infiltrated for 1 day. And the mass (Wa: g) was measured. Thereafter, the sample was allowed to stand in an oven at 150 ° C. for 1 hour, the mass was measured (Wb: g), and the degree of swelling of the copolymer with respect to the electrolytic solution was calculated from the following formula.
Swelling degree of copolymer to electrolyte (times) = (Wa−Wb) ÷ (Wb)

(11) Surface coverage of polymer layer The surface coverage of the polymer layer was measured using a scanning electron microscope (SEM) (model: S-4800, manufactured by HITACHI). The separator which is a sample was vapor-deposited on osmium, and observed under conditions of an acceleration voltage of 1.0 kV and 50 times, and the surface coverage was calculated from the following formula. In addition, the area | region where the porous structure of the base material for separators (polyolefin microporous film) or an electrode (electrode active material) surface is not visible in the SEM image was made into the polymer layer area | region.
Surface coverage of polymer layer (%) = Area of polymer layer ÷ (Area including pore part of substrate for separator or electrode (electrode active material) + Area of polymer layer) × 100
The surface coverage in each sample was measured three times, and the arithmetic average value was obtained.

(12) Interlayer Abundance of Polymer Layer Samples cut into 10 cm × 10 cm for each of the separator substrate (polyolefin microporous membrane) or electrode (electrode active material) and the separator substrate or electrode carrying a thermoplastic polymer The total mass of the three sheets was measured, and the amount of the polymer layer supported (solid content) in the sample was measured according to the following formula.
Abundance of polymer layer (g / m ² ) = [(total mass of three thermoplastic polymer-supporting substrates) − (total mass of three substrates)] ÷ 3 × 100

[Evaluation method]
(13) Adhesiveness between separator and electrode The adhesiveness between the separator and the electrode was evaluated by the following procedure.
(Preparation of positive electrode)
92.2% by mass of lithium cobalt composite oxide (LiCoO ₂ ) as a positive electrode active material, 2.3% by mass of flake graphite and acetylene black as a conductive material, and 3.2% by mass of polyvinylidene fluoride (PVDF) as a binder A slurry was prepared by dispersing in N-methylpyrrolidone (NMP). This slurry was applied to one side of a 20 μm thick aluminum foil serving as a positive electrode current collector with a die coater, dried at 130 ° C. for 3 minutes, and then compression molded with a roll press. At this time, the active material coating amount of the positive electrode was 250 g / m ² , and the active material bulk density was 3.00 g / cm ³ .

(Preparation of negative electrode)
A slurry was prepared by dispersing 96.9% by mass of artificial graphite as a negative electrode active material, 1.4% by mass of ammonium salt of carboxymethyl cellulose and 1.7% by mass of an aqueous dispersion of styrene-butadiene copolymer as a binder in purified water. This slurry was applied to one side of a 12 μm thick copper foil serving as a negative electrode current collector with a die coater, dried at 120 ° C. for 3 minutes, and then compression molded with a roll press. At this time, the active material application amount of the negative electrode was set to 106 g / m ² , and the active material bulk density was set to 1.35 g / cm ³ .

(Adhesion test)
The electrode obtained by the above method was cut into a width of 20 mm and a length of 40 mm. An electrolytic solution (manufactured by Toyama Pharmaceutical Co., Ltd.) in which ethylene carbonate and diethyl carbonate are mixed at a ratio (volume ratio) of 2: 3 is dropped onto this electrode until it is immersed in the electrode active material, and a separator base is added thereto. A material or a separator (size: width 30 mm, length 50 mm) was overlapped so that the electrode covered the whole surface of the separator substrate or separator. With respect to the material in which the thermoplastic polymer exists, that is, the separators of the respective examples obtained as described later, the thermoplastic polymer was superposed so as to be in contact with the positive electrode current collector. The obtained laminate was put in an aluminum zip bag and pressed at 80 ° C. and 10 MPa for 3 minutes. Thereafter, the laminate was taken out from the bag and the separator was peeled off from the electrode. At this time, the adhesion evaluation was performed according to the following evaluation criteria from the ratio of the adhesion area of the electrode active material remaining on the separator (the area on one side of the separator was 100%). In the adhesion test, when the inorganic filler is exposed on one side of the separator substrate or the separator, a thermoplastic resin is supported on the surface where the inorganic filler is not exposed, and the surface is the electrode. A laminate was prepared so as to be in contact with each other.
<Evaluation criteria>
The ratio of the adhesion area is 70% or more and 100% or less ... S
The ratio of the adhesion area is 50% or more and less than 70% ... A
The ratio of the adhesion area is 30% or more and less than 50%… B
The ratio of the adhesion area is 10% or more and less than 30%… C
Adhesion area ratio is 5% or more and less than 10%.
The ratio of the adhesion area is 0% or more and less than 5%… E

(14) Blocking resistance After preparing two separators or two electrodes cut to 20 mm × 100 mm, and superposing them, the laminate was made of a Teflon (registered trademark) sheet (Naflon (trademark) PTFE sheet manufactured by Nichias Corporation). TOMBO-No. 9000). About the obtained sample, the sample for a test was obtained by pressing in the lamination direction on condition of the following 1) and 2).
1) 25 ° C., 5 MPa, 3 minutes 2) 40 ° C., 5 MPa, 3 minutes The 90 ° peel strength between the separators in the sample after pressing was measured using a force gauge ZP5N and MX2-500N of Imada Co., Ltd. It was measured at 50 mm / min. Based on the peel strength value, the following evaluation criteria were used.
<Evaluation criteria>
20mN / mm or less ・ ・ ・ ○
More than 20mN / mm, 40mN / mm or less ... △
More than 40mN / mm ・ ・ ・ ×

(15) Simple adhesion test Separator formed by supporting a thermoplastic polymer and aluminum foil (made by Fuji Processed Paper Co., Ltd., thickness: 20 μm) as an adherend are cut into 20 mm × 100 mm, respectively, and a thermoplastic resin layer And the aluminum foil were overlapped with each other, and the laminate was sandwiched between Teflon (registered trademark) sheets (Naflon (trademark) PTFE sheet TOMBO-No. 9000 manufactured by NICHIAS Corporation). About each sample obtained in this way, the sample for a test was obtained by pressing in the lamination direction for 2 minutes on the conditions of 80 degreeC and 10 Mpa.
The peel strength between the separator and the aluminum foil of each test sample obtained was measured at a tensile speed of 50 mm / min using force gauge ZP5N and MX2-500N manufactured by Imada Corporation. Based on the peel strength value, the following evaluation criteria were used.
<Evaluation criteria>
4mN / mm or more… ○
2mN / mm or more and less than 4mN / mm… △
Less than 2 mN / mm… ×

(16) Powder fall test Various aqueous dispersions were diluted with water so that the solid content was 30 parts by mass to prepare a coating liquid containing a thermoplastic polymer (solid content 30% by mass). Subsequently, the coating liquid was apply | coated to the single side | surface of a separator using the micro gravure coater. With respect to the positive electrode active material surface and the negative electrode active material surface, a coating solution was applied using a spray coating method. Then, the coating liquid after application | coating was dried at 60 degreeC, and water was removed. The degree to which the dry coating film of the copolymer formed when the coated surface after drying was rubbed with a finger was evaluated by the following evaluation criteria. The adhesion with each substrate was evaluated by a powder falling test.
◎: White powder does not fall off at all ○: White powder is slightly generated △: White powder is generated but cannot be completely removed from the separator substrate or electrode side ×: White powder is generated And completely removed from the separator substrate or electrode side

(Dynamic surface tension)
Using an automatic dynamic surface tension meter “BP-D5” manufactured by Kyowa Interface Chemical Co., Ltd., the dynamic surface tension of each water dispersion (solid content 30% by mass) at a lifetime of 20 ms or less by the maximum bubble pressure method. Was measured. The measurement was carried out under conditions of constant temperature and humidity at a temperature of 23 ° C. ± 1 ° C. and a humidity of 50% ± 5%.

(Coating suitability)
Various water dispersions were diluted with water so that it might become 30 mass parts by solid content, and the coating liquid (solid content 30 mass%) containing a thermoplastic polymer was adjusted. Subsequently, the coating liquid was applied in the form of dots on both sides of the separator using a micro gravure coater. With respect to the positive electrode active material surface and the negative electrode active material surface, a coating solution was applied using a spray coating method. Then, the coating liquid after application | coating was dried at 60 degreeC, and water was removed. The coated surface after drying was observed with an SEM, and the regularity of the dot shape and the arrangement of the thermoplastic polymer was judged from the following criteria.
Dots exist independently, and the dot shape and arrangement are regular: ◎
The dots are independent, but the dot shape is slightly disturbed: ○
Missing dots and connections are seen in some places, and the shape and arrangement are clearly disturbed: △
The dot shape cannot be confirmed, and the coating state is clearly uneven: ×

[Synthesis Example 1]
(Water dispersion 1)
In a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 70.4 parts by mass of ion-exchanged water and “AQUALON KH1025” (registered trademark, 25% aqueous solution manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier 1.5 parts by mass were charged) (indicated as “KH1025” in the table). Next, the temperature inside the reaction vessel was raised to 80 ° C., and 7.5 parts by mass of a 2% aqueous solution of ammonium persulfate was added while maintaining the temperature at 80 ° C. Five minutes after the completion of the addition of the ammonium persulfate aqueous solution, the emulsion was dropped from the dropping tank into the reaction vessel over 150 minutes. The emulsified liquid is composed of 5 parts by weight of methacrylamide (indicated as “MAAm” in the table) as an ethylenically unsaturated monomer (A) having an amide group, and an ethylenically unsaturated monomer having a carboxyl group (b1). ) 1 part by weight of methacrylic acid (in the table, indicated as “MAA”), 1 part by weight of acrylic acid (in the table, indicated as “AA”), 2 as the ethylenically unsaturated monomer (b2) having a hydroxyl group -1 part by mass of hydroxyethyl methacrylate (in the table, expressed as “HEMA”), trimethylolpropane triacrylate (A-TMPT, trade name of Shin-Nakamura Chemical Co., Ltd.) as the crosslinkable monomer (b3), 0.7 parts by mass, expressed as “A-TMPT”, 0.4 parts by mass of γ-methacryloxypropyltrimethoxysilane (described as “AcSi” in the table), and having a cycloalkyl group 40 parts by mass of cyclohexyl methacrylate (described as “CHMA” in the table) as the tyrenic unsaturated monomer (b4), and methyl methacrylate as the (meth) acrylic acid ester monomer (b7) other than the above (in the table, “ 8 parts by weight of MMA), 2 parts by weight of butyl methacrylate (described as BMA in the table), 2 parts by weight of butyl acrylate (indicated as “BA” in the table), 2-ethylhexyl acrylate (in the table, “EHA”) Notation) 40 parts by mass, 3 parts by mass of “AQUALON KH1025” (registered trademark, 25% aqueous solution manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as emulsifier, 7.5 parts by mass of 2% aqueous solution of ammonium persulfate, and 52 parts by mass of ion-exchanged water The mixture was prepared by mixing for 5 minutes with a homomixer.
After completion of dropping of the emulsion, the temperature inside the reaction vessel was maintained at 80 ° C. for 90 minutes, and then cooled to room temperature. The obtained emulsion was adjusted to pH = 9.0 with an aqueous ammonium hydroxide solution (25% aqueous solution) to obtain an aqueous dispersion having a concentration of 40% (aqueous dispersion 1). About the copolymer in the obtained water dispersion 1, Tg, an average particle diameter, and the swelling degree with respect to electrolyte solution were measured with the said method. The obtained results are shown in Table 1.

[Synthesis Examples 2 to 4, 7 to 14]
(Water dispersions 2-4, 7-14)
Aqueous dispersions 2 to 4 and 7 to 14 were obtained in the same manner as in Synthesis Example 1 except that the types and mixing ratios of the raw materials were changed as shown in Table 1. In the table, “AAm” means acrylamide which is one type of ethylenically unsaturated monomer (A) having an amide group. About the copolymer in the obtained water dispersions 2-4 and 7-14, Tg, a particle diameter, and the swelling degree with respect to electrolyte solution were measured with the said method. The obtained results are shown in Table 1. In the table, the composition of raw materials is based on mass.

[Synthesis Example 5]
(Water dispersion 5)
In a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 138 parts by mass of ion-exchanged water and “AQUALON KH1025” (registered trademark, 25% aqueous solution manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as an emulsifier 1.5 parts by mass were charged. Next, the temperature inside the reaction vessel was raised to 80 ° C., and 7.5 parts by mass of a 2% aqueous solution of ammonium persulfate was added while maintaining the temperature at 80 ° C. Five minutes after the completion of the addition of the ammonium persulfate aqueous solution, the emulsion was dropped from the dropping tank into the reaction vessel over 150 minutes. The emulsion is 10 parts by mass of acrylamide (shown as “AAm” in the table) as the ethylenically unsaturated monomer (A) having an amide group, and the ethylenically unsaturated monomer (b1) having a carboxyl group. As 1 part by mass of methacrylic acid (indicated as “MAA” in the table), 1 part by mass of acrylic acid (indicated as “AA” in the table), 2-ethylenically unsaturated monomer (b2) having a hydroxyl group as 2- 1 part by mass of hydroxyethyl methacrylate (indicated in the table as “HEMA”), trimethylolpropane triacrylate (A-TMPT, trade name of Shin-Nakamura Chemical Co., Ltd.) as the crosslinkable monomer (b3), “ "A-TMPT") 0.7 parts by mass, γ-methacryloxypropyltrimethoxysilane (denoted as "AcSi" in the table) 0.4 parts by mass, and having a cycloalkyl group 40 parts by mass of cyclohexyl methacrylate (described as “CHMA” in the table) as the renically unsaturated monomer (b4), methyl methacrylate (in the table, “CHMA”) as the other (meth) acrylic acid ester monomer (b7) 3 parts by weight of MMA), 2 parts by weight of butyl methacrylate (described as BMA in the table), 2 parts by weight of butyl acrylate (indicated as “BA” in the table), 2-ethylhexyl acrylate (in the table, “EHA”) Notation) 40 parts by mass, 3 parts by mass of “AQUALON KH1025” (registered trademark, 25% aqueous solution manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as emulsifier, 7.5 parts by mass of 2% aqueous solution of ammonium persulfate, and 72 parts by mass of ion-exchanged water The mixture was prepared by mixing for 5 minutes with a homomixer.
After completion of dropping of the emulsion, the temperature inside the reaction vessel was maintained at 80 ° C. for 90 minutes, and then cooled to room temperature. The obtained emulsion was adjusted to pH = 9.0 with an aqueous ammonium hydroxide solution (25% aqueous solution) to obtain an aqueous dispersion having a concentration of 30% (aqueous dispersion 5). About the copolymer in the obtained water dispersion 5, Tg, an average particle diameter, and the swelling degree with respect to electrolyte solution were measured with the said method. The obtained results are shown in Table 1.

[Synthesis Example 6]
(Water dispersion 6)
An aqueous dispersion 6 was obtained in the same manner as in Synthesis Example 5 except that the type and blending ratio of the raw materials were changed as shown in Table 1. About the copolymer in the obtained water dispersion 6, Tg, a particle diameter, and the swelling degree with respect to electrolyte solution were measured with the said method. The obtained results are shown in Table 1. In the table, the composition of raw materials is based on mass.

[Production Example 1]
(Manufacture of base material B1 (base material for separator))
Mv is 700,000, 45 parts by mass of homopolymer high-density polyethylene, Mv is 300,000, homopolymer high-density polyethylene is 45 parts by mass, and Mv is 400,000. 10 parts by mass of a mixture of a homopolymer having 150,000 and polypropylene (mass ratio = 4: 3) was dry blended using a tumbler blender. 1 part by mass of tetrakis- [methylene- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane as an antioxidant was added to 99 parts by mass of the obtained polyolefin mixture, and again a tumbler blender. Was used for dry blending to obtain a mixture. The obtained mixture was supplied to the twin screw extruder by a feeder under a nitrogen atmosphere. Further, liquid paraffin (kinematic viscosity at 37.78 ° C .: 7.59 × 10 −5 m ² / s) was injected into the extruder cylinder by a plunger pump. The operating conditions of the feeder and the pump were adjusted so that the ratio of liquid paraffin in the total mixture to be extruded was 65 parts by mass, that is, the polymer concentration was 35 parts by mass.

  Next, they are melt-kneaded while being heated to 230 ° C. in a twin-screw extruder, and the obtained melt-kneaded product is extruded through a T-die onto a cooling roll controlled at a surface temperature of 80 ° C. A sheet-like molded product was obtained by bringing into contact with a cooling roll and molding by cooling. The sheet was stretched by a simultaneous biaxial stretching machine at a magnification of 7 × 6.4 and a temperature of 112 ° C., then immersed in methylene chloride, extracted by removing liquid paraffin and dried, and then a temperature of 130 by a tenter stretching machine. The film was stretched 2 times in the transverse direction at ° C. Thereafter, the stretched sheet was relaxed by about 10% in the width direction and heat-treated to obtain a base material B1 shown in Table 2.

  About the obtained base material B1, various physical properties were measured by the said method. Moreover, about the obtained base material B1, blocking resistance, adhesiveness, and the said simple adhesion test were done with the said method. The obtained results are shown in Table 2.

[Production Example 2]
(Manufacture of base material B2)
Substrate B2 was obtained by the same operation as in Production Example 1 except that the stretching temperature and the relaxation rate were adjusted. The obtained base material B2 was evaluated and tested by the above method in the same manner as in Production Example 1. The obtained results are shown in Table 2.

[Production Example 3]
(Manufacture of base material B3)
47.5 parts by mass of homopolymer high-density polyethylene having a viscosity average molecular weight of 700,000, 47.5 parts by mass of homopolymer high-density polyethylene having a viscosity average molecular weight of 250,000, and 5 parts by mass of homopolymer polypropylene having a viscosity average molecular weight of 400,000 Was dry blended using a tumbler blender. 1 part by mass of pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as an antioxidant is added to 99 parts by mass of the obtained polymer mixture, and again The mixture was obtained by dry blending using a tumbler blender. The obtained mixture was substituted with nitrogen and then fed to the twin-screw extruder with a feeder under a nitrogen atmosphere. Moreover, liquid paraffin was inject | poured into the extruder cylinder with the plunger pump.
The feeder and the pump were adjusted so that the liquid paraffin content ratio in the total mixture melt-kneaded and extruded was 67 mass% (resin composition concentration was 33 mass%).

  The melt-kneaded product was extruded and cast on a cooling roll through a T-die to obtain a sheet-like molded product. Then, base material B3 was obtained by operation similar to manufacture example 1 except having adjusted the extending | stretching temperature and the relaxation rate. About the obtained base material B3, it carried out similarly to manufacture example 1, evaluated various physical properties, blocking resistance, and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 4]
(Manufacture of base material B4)
25 parts by mass of ultra high molecular weight polyethylene having a viscosity average molecular weight of 2 million, 15 parts by mass of high density polyethylene having a viscosity average molecular weight of 700,000, 30 parts by mass of high density polyethylene having a viscosity average molecular weight of 250,000, and 120,000 in viscosity average molecular weight 30 parts by mass of copolymer polyethylene having a propylene unit content of 1 mol% was dry blended using a tumbler blender. 0.3 parts by mass of pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as an antioxidant was added to 99 parts by mass of the obtained polymer mixture. The mixture was obtained by dry blending again using a tumbler blender. The obtained mixture was substituted with nitrogen and then fed to the twin-screw extruder with a feeder under a nitrogen atmosphere. Liquid paraffin was injected into the extruder cylinder by a plunger pump.
The feeder and pump were adjusted so that the liquid paraffin content ratio in the total mixture melt-kneaded and extruded was 65 mass% (resin composition concentration was 35 mass%).

  The melt-kneaded product was extruded and cast on a cooling roll through a T-die to obtain a sheet-like molded product. Then, base material B4 was obtained by operation similar to manufacture example 1 except having adjusted the extending | stretching temperature and the relaxation rate. About the obtained base material B4, it carried out similarly to manufacture example 1, evaluated various physical properties, blocking resistance, and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 5]
(Manufacture of base material B5)
A base material B5 was obtained by the same operation as in Production Example 3, except that the stretching temperature and the relaxation rate were adjusted. About the obtained base material B5, it carried out similarly to the manufacture example 1, evaluated various physical properties, blocking resistance, and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 6]
(Manufacture of base material B6)
19.2 parts by weight of ultra high molecular weight polyethylene with a viscosity average molecular weight of 1 million, 12.8 parts by weight of high density polyethylene with a viscosity average molecular weight of 250,000, 48 parts by weight of dioctyl phthalate (DOP), and 20 parts by weight of fine silica After granulation, the mixture was melt-kneaded by a twin-screw extruder equipped with a T-die at the tip, extruded, rolled with rolls heated from both sides, and formed into a sheet having a thickness of 110 μm. DOP and fine silica were extracted and removed from the molded product to prepare a microporous membrane. Two microporous membranes were stacked and stretched 5 times in the MD direction at 120 ° C. and 2 times in TD at 120 ° C., and finally heat treated at 137 ° C. to obtain a base material B6. About the obtained base material B6, it carried out similarly to manufacture example 1, evaluated various physical properties, blocking resistance, and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 7]
(Manufacture of base material B7)
96.0 parts by mass of aluminum hydroxide oxide (average particle size 1.0 μm), acrylic latex (solid content concentration 40%, average particle size 145 nm, minimum film forming temperature 0 ° C. or less) 4.0 parts by mass, polycarboxylic An aqueous solution of ammonium acid (SN Dispersant 5468, manufactured by San Nopco) is uniformly dispersed in 100 parts by mass of water to prepare a coating solution, and a micro gravure coater is used on the surface of the polyolefin resin porous membrane B1. Applied. Water was removed by drying at 60 ° C., and a porous layer was formed with a thickness of 2 μm to obtain a base material B7. About obtained base material B7, it carried out similarly to manufacture example 1, evaluated blocking resistance and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 8]
(Manufacture of base material B8)
A porous layer having a thickness of 4 μm was formed on one surface of the substrate B1 in the same manner as in Production Example 7 to obtain a substrate B8. About obtained base material B8, it carried out similarly to manufacture example 1, evaluated blocking resistance and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 9]
(Manufacture of base material B9)
A porous layer having a thickness of 3 μm was formed on one surface of the base material B2 in the same manner as in Production Example 7 to obtain a base material B9. About obtained base material B9, it carried out similarly to manufacture example 1, evaluated blocking resistance and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 10]
(Manufacture of base material B10)
A porous layer having a thickness of 7 μm was formed on one surface of the base material B5 in the same manner as in Production Example 7 to obtain a base material B10. About obtained base material B10, it carried out similarly to manufacture example 1, evaluated blocking resistance and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 11]
(Manufacture of base material B11)
95.0 parts by mass of calcined kaolin (wet kaolin mainly composed of kaolinite (Al ₂ Si ₂ O ₅ (OH) ₄ ), calcined at high temperature, average particle size 1.8 μm), acrylic latex (solid content 180 parts by mass of water of 5.0 parts by mass with a concentration of 40%, an average particle size of 220 nm, a minimum film forming temperature of 0 ° C. or less, and 0.5 parts by mass of an aqueous ammonium polycarboxylate (SN Dispersant 5468 manufactured by San Nopco) A coating solution was prepared by uniformly dispersing the coating solution on the surface of the base material B3 and coated on the surface of the substrate B3 using a micro gravure coater. Water was removed by drying at 60 ° C., and a porous layer was formed with a thickness of 6 μm to obtain a base material B11. About obtained base material B11, it carried out similarly to manufacture example 1, evaluated blocking resistance and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Production Example 12]
(Manufacture of base material B12)
Except that the stretching temperature and relaxation rate were adjusted, the same procedure as in Production Example 1 was followed, with a basis weight of 4.6 g / m ² , a film thickness of 7 μm, a porosity of 38%, an air permeability of 150 seconds, and a piercing A base material having a strength of 270 g and an average pore size of 0.070 μm was obtained. A porous layer having a thickness of 3 μm was formed on one surface of the base material in the same manner as in Production Example 7 to obtain base material B12. About obtained base material B12, it carried out similarly to manufacture example 1, evaluated blocking resistance and adhesiveness, and performed the said simple adhesion test. The obtained results are shown in Table 2.

[Example 1]
Aqueous dispersions 1 and 11 are diluted with water so that the solid content is 30 parts by mass, and mixed so that the aqueous dispersion 1 = 25 and the aqueous dispersion 11 = 75 by mass ratio, and contain a thermoplastic polymer. A coating solution (solid content: 30% by mass) was prepared. Subsequently, the coating liquid was apply | coated to the single side | surface of base material B1 using the micro gravure coater. Then, the coating liquid after application | coating was dried at 60 degreeC, and water was removed. Furthermore, the coating solution was similarly applied to the other surface of the substrate B1, and dried again in the same manner as described above. In this way, the separator which formed the polymer layer on both surfaces of base material B1 was obtained. In this separator, the surface coverage of the polymer layer was 30%, and the average thickness of the polymer layer was 1 μm. Moreover, when confirmed with SEM, the polymer layer existed regularly arranged in the shape of a substantially circular dot on the surface of the base material B1. The amount of the polymer supported on one side of the substrate B1 was 0.3 g / m ² .
About the obtained separator, the blocking resistance, powder fall-off property, adhesiveness, and the said simple adhesion test were done with the said method. The obtained results are shown in Table 3.

[Examples 2 to 25, Comparative Examples 1 to 6]
The solid content of the aqueous dispersion was adjusted with water so as to be 30 parts by mass as in Example 1. The coating liquid of each example was prepared in the same manner as in Example 1 except that the type and mixing ratio (% by mass) of the water dispersion and the type of the base material for the separator were changed as shown in Tables 2 and 3 to 7. The separator which prepared and carried each thermoplastic polymer on the various base materials which are separators was produced. Various physical properties and evaluation / test results of the obtained separator are shown in Tables 3 to 7.
Regarding Examples 2 to 25, the surface coverage of the polymer layer was 30%, and the average thickness of the polymer layer was 1 μm. Further, as confirmed by SEM, the polymer layers were regularly arranged in a substantially circular dot shape on the surface of each substrate.
Regarding Comparative Examples 1 to 6, the surface coverage of the polymer layer was about 10%, and the average thickness of the polymer layer was 1 μm. Further, as confirmed by SEM, the polymer layer was irregularly present in various sizes and shapes on the surface of the base material B1, and dot omission, flow, joining of adjacent dots, etc. were observed.

[Example 26]
The solid content of the aqueous dispersion was diluted with water so as to be 30 parts by mass as in Example 1, and the type and mixing ratio (% by mass) of the aqueous dispersion were adjusted as shown in Table 6, and the type of base material Was designated as B1 in Table 2. The aqueous dispersion to be applied was spray-coated on the positive electrode active material and the negative electrode active material, and then the applied coating solution was dried at 60 ° C. to remove water. Thus, each electrode in which the thermoplastic polymer layer was formed on the positive electrode active material and the negative electrode active material was obtained. When confirmed by SEM, in this electrode, the surface coverage of the polymer layer was 30 to 35%, and the thickness of the polymer layer was 0.5 to 1.2 μm (average 1.0 μm). Moreover, the polymer layer was circular or elliptical on the surface of various substrates, and each existed as an independent dot shape. About the obtained thermoplastic polymer carrying | support electrode, the blocking resistance, powder fall-off property, and the adhesiveness test were done with the said method. The results obtained are shown in Table 6. The simple adhesion test in Table 6 is a test for simply confirming the presence or absence of adhesiveness of the thermoplastic polymer. Therefore, the thermoplastic polymer described in Table 6 was formed and supported on the substrate B1 by the method described in Example 1 instead of supporting the thermoplastic polymer on the electrode, and the simple adhesion test was performed. evaluated.

  ADVANTAGE OF THE INVENTION According to this invention, the laminated body excellent in the adhesiveness of an electrode and a separator can be provided. Therefore, the present invention is useful as a laminated body for an electricity storage device such as a battery such as a non-aqueous electrolyte secondary battery, a capacitor, and a capacitor, and has industrial applicability in these fields.

Claims (25)

At least one electrode;
A separator substrate;
A layer containing a thermoplastic polymer formed at least in part between the separator substrate and the electrode;
A laminate comprising:
The laminated body in which the said thermoplastic polymer contains the copolymer which has an ethylenically unsaturated monomer which has an amide group as a monomer unit.   The laminate according to claim 1, wherein the ethylenically unsaturated monomer having an amide group is acrylamide and / or methacrylamide.   The laminated body of Claim 1 or 2 whose content in the copolymer of the ethylenically unsaturated monomer which has the said amide group is 1-15 mass%.   Any of Claims 1-3 whose peeling strength after pressing the thermoplastic polymer layer containing the said copolymer with respect to aluminum foil for 2 minutes at the temperature of 80 degreeC and the pressure of 10 Mpa is 4 N / m or more. The laminate according to claim 1.   The laminated body of any one of Claims 1-4 in which the layer containing the said thermoplastic polymer exists in a dot form with respect to a surface perpendicular | vertical to a lamination direction.   The laminate according to any one of claims 1 to 5, wherein the separator substrate is a polyolefin microporous film.   An electrical storage device provided with the laminated body of any one of Claims 1-6.   A lithium ion secondary battery provided with the laminated body of any one of Claims 1-6. A separator for an electricity storage device comprising a separator substrate and a layer containing a thermoplastic polymer in at least a part of at least one surface of the separator substrate,
A copolymer in which the thermoplastic polymer has, as monomer units, an ethylenically unsaturated monomer having an amide group and another monomer copolymerizable with the ethylenically unsaturated monomer having an amide group A separator for an electricity storage device, comprising:   The separator for an electricity storage device according to claim 9, wherein the ethylenically unsaturated monomer having an amide group is acrylamide and / or methacrylamide.   The separator for an electricity storage device according to claim 9 or 10, wherein the content of the ethylenically unsaturated monomer having an amide group in the copolymer is 1 to 15% by mass.   The separator for an electricity storage device according to any one of claims 9 to 11, wherein the peel strength after pressing the aluminum foil at a temperature of 80 ° C and a pressure of 10 MPa for 2 minutes is 4 N / m or more.   The separator for electrical storage devices of any one of Claims 9-12 in which the layer containing the said thermoplastic polymer exists in the dot form on the at least single side | surface of the said base material for separators.   The electrical storage device separator according to any one of claims 9 to 13, wherein the separator substrate is a polyolefin microporous membrane.   An electricity storage device comprising the separator for an electricity storage device according to any one of claims 9 to 14.   A lithium ion secondary battery provided with the separator for electrical storage devices of any one of Claims 9-14.   A copolymer having, as monomer units, an ethylenically unsaturated monomer having an amide group and another monomer copolymerizable with the ethylenically unsaturated monomer having an amide group.   The copolymer according to claim 17, wherein the ethylenically unsaturated monomer having an amide group is acrylamide and / or methacrylamide.   The copolymer of Claim 17 or 18 whose content in the copolymer of the ethylenically unsaturated monomer which has the said amide group is 1-15 mass%.   The copolymer of any one of Claims 17-19 whose swelling degree of the said copolymer with respect to the mixed solvent (mass ratio 2: 3) of ethylene carbonate and diethyl carbonate is 5.0 times or less.   The copolymer according to any one of claims 17 to 20, wherein the copolymer is produced by emulsion polymerization.   The copolymer according to any one of claims 17 to 21, wherein the copolymer is used in an electricity storage device.   The copolymer of any one of Claims 17-21 used for the said separator for an electrical storage device, or an electrode.   An aqueous dispersion comprising water and the copolymer according to any one of claims 17 to 23 dispersed in the water.   25. The water according to claim 24, wherein, in the aqueous dispersion, the dynamic surface tension value with a lifetime of 20 milliseconds or less by a maximum foam pressure method when the copolymer solid content is 30% is 72 mN / m or less. Dispersion.

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