JP2020074308A - Adhesive sheet for battery and lithium ion battery - Google Patents

Abstract

To provide an adhesive composition which presents a high adhesive strength to an adherend and an adhesive agent is hard to be dissolved in an electrolyte even in a case where an adhesive sheet is brought into contact with the electrolyte, an adhesive sheet for battery and a lithium ion battery.SOLUTION: The present invention relates to an adhesive sheet 1 for battery comprising a substrate 11 and an adhesive agent layer 13. In the adhesive sheet 1 for battery, the substrate 11 is a film constituted of a polymer having a nitrogen containing ring structure in a main chain. The adhesive agent layer 13 is formed from an adhesive composition containing: a (meta-)acrylic acid ester polymer which contains (meta-)acrylic acid alkyl ester of which the carbon number of alkyl groups is 6 or more and 20 or less and a monomer including a carboxyl group in a molecule, as a monomer unit constituting the polymer, and of which the weight average molecular weight is 50,000 or more and 2,500,000 or less and the glass transition temperature is equal to or higher than -70°C and lower than 0°C; and a metal chelate-based crosslinking agent. A gel fraction of an adhesive agent constituting the adhesive agent layer 13 after immersing the adhesive agent in a solvent of a nonaqueous solution at 80°C for 72 hours is 80% or more and 100% or less.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive sheet for a battery, a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for a battery, and a lithium-ion battery manufactured using them.

  In some batteries, a strip-shaped laminate in which a positive electrode, a negative electrode, and a separator located between them are laminated is housed inside in a wound state. Electrode take-out tabs made of a conductor are connected to the positive electrode and the negative electrode, respectively, and the positive electrode and the negative electrode are electrically connected to the positive electrode terminal and the negative electrode terminal of the battery, respectively, through these electrode take-out tabs. ..

  An adhesive tape is used for winding the laminated body and fixing the electrode take-out tab to the electrode. Patent Document 1 discloses such an adhesive tape. This pressure-sensitive adhesive tape comprises a base material and a pressure-sensitive adhesive layer provided on one surface of the base material, and the pressure-sensitive adhesive layer is mainly composed of rubber, particularly butyl rubber.

JP, 2011-138632, A

  The adhesive tape used inside the battery may come into contact with the electrolyte solution filled inside the battery or may be exposed to the heat generated during charging and discharging. Particularly in recent years, development of small-sized and high-performance batteries has been promoted, and the adhesive tape used inside the batteries is exposed to more severe conditions.

  In order to achieve good battery performance, the pressure-sensitive adhesive tape must maintain high adhesion with the adherend even when exposed to the severe conditions described above, and It is required that it does not elute in the electrolytic solution and does not adversely affect the battery performance. However, the conventional pressure-sensitive adhesive tape may not be able to sufficiently meet such requirements.

  The present invention has been made in view of such a situation, even when the pressure-sensitive adhesive sheet is in contact with the electrolytic solution, while exhibiting good adhesive force to the adherend, the adhesive is electrolytic It is an object of the present invention to provide an adhesive composition, an adhesive sheet for a battery, and a lithium ion battery that are difficult to elute in a liquid.

  In order to achieve the above-mentioned object, firstly, the present invention is a battery pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer laminated on one surface side of the base material, wherein the base material is: A film made of a polymer having a nitrogen-containing ring structure in the main chain, wherein the pressure-sensitive adhesive layer has a (meth) acryl having 6 or more and 20 or less carbon atoms of an alkyl group as a monomer unit constituting the polymer. Adhesiveness containing an acid alkyl ester and a (meth) acrylic acid ester polymer containing a monomer having a carboxy group in the molecule and having a weight average molecular weight of 50,000 or more and 2,500,000 or less, and a metal chelate crosslinking agent. A glass transition temperature of the (meth) acrylic acid ester polymer (A) is −70 ° C. or higher and lower than 0 ° C., and the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not formed. Solvent for aqueous electrolyte Gel fraction of the pressure-sensitive adhesive in after immersion for 72 hours at 80 ° C. is 80% or more, to provide a battery for a pressure-sensitive adhesive sheet, wherein 100% or less (invention 1). In addition, in the present specification, a sheet includes the concept of a tape.

  In the above invention (Invention 1), the (meth) acrylic acid ester polymer is a (meth) acrylic acid having an alkyl group having 6 or more and 20 or less carbon atoms as a monomer unit constituting the polymer. By containing the alkyl ester, good adhesiveness is exhibited and, due to the hydrophobicity, the electrolytic solution resistance is also excellent. Therefore, when the pressure-sensitive adhesive layer of the battery pressure-sensitive adhesive sheet is formed of the pressure-sensitive adhesive composition according to the above invention (Invention 1), the pressure-sensitive adhesive layer swells even when the battery pressure-sensitive adhesive sheet comes into contact with the electrolytic solution. Cohesive failure is suppressed by this, excellent adhesive force is exerted on the adherend, and the adhesive is difficult to elute in the electrolytic solution.

  In the said invention (invention 1), it is preferable that the said (meth) acrylic acid ester polymer contains the monomer which has an alicyclic structure in a molecule as a monomer unit which comprises the said polymer (invention 2).

  In the above inventions (Inventions 1 and 2), a hard coat layer is preferably formed on the surface of the base material on the side of the pressure-sensitive adhesive layer (Invention 3). The hard coat layer in the present specification means a layer made of a material harder than the base material, and does not mean a layer existing in the outermost layer of the film.

  Secondly, the invention is characterized in that two or more conductors are fixed in contact with each other inside the battery using the battery pressure-sensitive adhesive sheet (inventions 1 to 3). An ion battery is provided (Invention 4).

  According to the pressure-sensitive adhesive composition, the battery pressure-sensitive adhesive sheet and the lithium-ion battery according to the present invention, even when the battery pressure-sensitive adhesive sheet comes into contact with the electrolytic solution, the pressure-sensitive adhesive layer is prevented from cohesive failure due to swelling. The battery pressure-sensitive adhesive sheet exhibits excellent adhesion to the adherend, and the pressure-sensitive adhesive does not easily elute into the electrolytic solution.

It is sectional drawing of the adhesive sheet for batteries which concerns on one Embodiment of this invention. It is a partial cross-section disassembled perspective view of the lithium ion battery which concerns on one Embodiment of this invention. It is a development perspective view of the electrode body of the lithium ion battery concerning one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
An adhesive composition according to an embodiment of the present invention is an adhesive composition for forming an adhesive layer of a battery adhesive sheet. The "battery pressure-sensitive adhesive sheet" in the present specification is a pressure-sensitive adhesive sheet used in a place where it may come into contact with an electrolytic solution in the production of a battery, preferably a pressure-sensitive adhesive sheet used inside a battery, It may be an adhesive sheet for battery interior. The battery is preferably a non-aqueous battery. Therefore, the electrolytic solution used in the battery is preferably a non-aqueous electrolytic solution. The pressure-sensitive adhesive sheet for a battery in the present specification is preferably a pressure-sensitive adhesive sheet that is attached to a portion inside the non-aqueous battery that may be immersed in the electrolytic solution or a portion that may come into contact with the electrolytic solution. A lithium ion battery is particularly preferable as the non-aqueous battery.

  In the pressure-sensitive adhesive composition according to the present embodiment (hereinafter sometimes referred to as “pressure-sensitive adhesive composition P”), the number of carbon atoms of the alkyl group is 6 or more and 20 or less as a monomer unit constituting the polymer ( Containing a (meth) acrylic acid alkyl ester and a (meth) acrylic acid ester polymer (A) containing a monomer having a carboxy group in the molecule (carboxy group-containing monomer), preferably a metal chelate-based cross-linking agent (B) And particularly preferably further contains a silane coupling agent (C). In addition, in this specification, a (meth) acrylic acid ester means both an acrylic acid ester and a methacrylic acid ester. The same applies to other similar terms. In addition, the term “polymer” also includes the concept of “copolymer”.

(1) Each component (1-1) (meth) acrylic acid ester polymer (A)
The (meth) acrylic acid ester polymer (A) has, as a monomer unit constituting the polymer, a (meth) acrylic acid alkyl ester having an alkyl group having 6 to 20 carbon atoms, and a carboxy group in the molecule. Including a monomer (carboxy group-containing monomer).

  The (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group imparts good adhesiveness to the obtained pressure-sensitive adhesive and exhibits hydrophobicity due to the large number of carbon atoms in the alkyl group. This hydrophobic property has a property of low affinity with an electrolytic solution (including a non-aqueous electrolytic solution). Therefore, the obtained pressure-sensitive adhesive exhibits a good pressure-sensitive adhesive force and also has excellent electrolytic solution resistance due to the above-mentioned hydrophobicity. Therefore, when the pressure-sensitive adhesive layer of the battery pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition P containing the (meth) acrylic acid ester polymer (A), when the battery pressure-sensitive adhesive sheet comes into contact with the electrolytic solution (dipped (Including the case), the cohesive failure of the pressure-sensitive adhesive layer due to swelling is suppressed, and the pressure-sensitive adhesive sheet for a battery exhibits excellent adhesion to an adherend. Further, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is less likely to be eluted in the electrolytic solution, and the pressure-sensitive adhesive does not adversely affect the battery performance. By these, malfunction of the battery, thermal runaway, and short circuit due to the battery adhesive sheet are suppressed.

  The alkyl group of the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group may be linear or branched. From the viewpoint of hydrophobicity, the alkyl group needs to have 6 or more carbon atoms, preferably 7 or more carbon atoms, and more preferably 8 or more carbon atoms. On the other hand, the carbon number of the alkyl group needs to be 20 or less from the viewpoint of adhesiveness, preferably 18 or less, particularly preferably 15 or less, and further 10 or less. Is preferred.

  Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 6 to 20 carbon atoms include, for example, n-hexyl (meth) acrylic acid, 2-ethylhexyl (meth) acrylic acid, isooctyl (meth) acrylic acid, and (meth) acrylic acid. ) N-decyl acrylate, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate and the like can be mentioned. Among the above-mentioned (meth) acrylic acid alkyl esters, from the viewpoint of adhesiveness and hydrophobicity, (meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid isooctyl, (meth) acrylic acid n-decyl, acrylic acid n-dodecyl, etc. Are preferred, and 2-ethylhexyl acrylate and isooctyl acrylate are particularly preferred. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) may contain 50% by mass or more of a (meth) acrylic acid alkyl ester having an alkyl group having 6 to 20 carbon atoms as a monomer unit constituting the polymer. The content is preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 75% by mass or more. When the (meth) acrylic acid alkyl ester is contained in an amount of 50% by mass or more, the (meth) acrylic acid ester polymer (A) can exhibit more excellent tackiness and electrolytic solution resistance. Further, the (meth) acrylic acid ester polymer (A) contains 99% by mass or less of a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms as a monomer unit constituting the polymer. Is more preferable, 97% by mass or less is more preferable, 90% by mass or less is particularly preferable, and 85% by mass or less is further preferable. By setting the amount of the (meth) acrylic acid alkyl ester to 99% by mass or less, another monomer component can be introduced in a suitable amount into the (meth) acrylic acid ester polymer (A).

  On the other hand, the carboxy group-containing monomer contained in the (meth) acrylic acid ester polymer (A) as a monomer unit constituting the polymer has an effect of improving the adhesive force of the obtained pressure-sensitive adhesive. When the adhesive composition P contains a metal chelate-based cross-linking agent (B) described below, the carboxy group derived from the carboxy group-containing monomer has a metal chelate at the time of cross-linking the (meth) acrylic acid ester polymer (A). By reacting with the system crosslinking agent (B), a crosslinked structure having a three-dimensional network structure is formed. The pressure-sensitive adhesive having a crosslinked structure by the reaction between the carboxy group and the metal chelate-based crosslinking agent (B) has high resistance to an electrolytic solution, particularly a non-aqueous electrolytic solution, and is difficult to elute even when contacted with the electrolytic solution. Therefore, the pressure-sensitive adhesive obtained is difficult to be eluted by the electrolytic solution in combination with the electrolytic solution resistance by the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group.

  Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. Of these, acrylic acid is preferred. With acrylic acid, the above effects are more excellent. The carboxy group-containing monomers may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains a carboxyl group-containing monomer as a monomer unit constituting the polymer at a lower limit of 0.5% by mass or more, and particularly at least 1% by mass. It is preferable that the content be 3% by mass or more. In addition, the (meth) acrylic acid ester polymer (A) preferably contains a carboxy group-containing monomer as a monomer unit constituting the polymer in an amount of 30% by mass or less as an upper limit, and particularly preferably 20% by mass or less. It is preferable that the content is 10% by mass or less. When the (meth) acrylic acid ester polymer (A) contains the carboxy group-containing monomer in the above-mentioned amount as a monomer unit, the above-mentioned effect is more excellent in the obtained pressure-sensitive adhesive.

  The (meth) acrylic acid ester polymer (A) preferably contains, as a monomer unit constituting the polymer, a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer). This alicyclic structure-containing monomer exhibits hydrophobicity because it is bulky. Therefore, the obtained pressure-sensitive adhesive becomes more excellent in electrolytic solution resistance in combination with the hydrophobicity due to the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group. Therefore, even when the pressure-sensitive adhesive sheet for a battery is in contact with the electrolytic solution, cohesive failure due to swelling of the pressure-sensitive adhesive layer is more effectively suppressed, and the pressure-sensitive adhesive sheet for a battery is more excellent for an adherend. Demonstrate the adhesive strength. In addition, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is less likely to be eluted by the electrolytic solution.

  The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may have a saturated structure or may partially have an unsaturated bond. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic ring or a tricyclic ring. From the viewpoint of the above-mentioned hydrophobicity and resistance to the electrolytic solution, the alicyclic structure is preferably a polycyclic alicyclic structure (polycyclic structure). Furthermore, in consideration of the compatibility between the (meth) acrylic acid ester polymer (A) and other components, the polycyclic structure is particularly preferably a bicyclic ring to a tetracyclic ring. Further, from the viewpoint of effectively exhibiting electrolytic solution resistance, the carbon number of the alicyclic structure (refers to all the carbon numbers of the portion forming the ring, and when a plurality of rings are present independently, , The total number of carbon atoms thereof) is usually preferably 5 or more, and particularly preferably 7 or more. On the other hand, although the upper limit of the number of carbon atoms of the alicyclic structure is not particularly limited, it is preferably 15 or less, and particularly preferably 10 or less from the viewpoint of compatibility as in the above.

  Examples of the alicyclic structure include cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, etc.) , Cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, cubane skeleton, basketane skeleton, hausan skeleton, spiro skeleton, and the like, among which, more excellent durability is exhibited, Those having a dicyclopentadiene skeleton (carbon number of alicyclic structure: 10), adamantane skeleton (carbon number of alicyclic structure: 10) or isobornyl skeleton (carbon number of alicyclic structure: 7) are preferable, and particularly Contains an isobornyl skeleton Preference is.

  The alicyclic structure-containing monomer is preferably a (meth) acrylic acid ester monomer containing the skeleton, and specifically, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (meth) Examples thereof include adamantyl acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. Among them, (meth) acrylic exhibiting superior durability. Dicyclopentanyl acid, adamantyl (meth) acrylate or isobornyl (meth) acrylate is preferable, and isobornyl (meth) acrylate is particularly preferable. These may be used alone or in combination of two or more.

  When the (meth) acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, the (meth) acrylic acid ester polymer (A) is more hydrophobic. From the viewpoint of increasing the content, the content of the alicyclic structure-containing monomer is preferably 5% by mass or more, particularly preferably 7.5% by mass or more, and further preferably 10% by mass or more. In addition, the (meth) acrylic acid ester polymer (A) has a viewpoint of preventing the electrolyte solution resistance from decreasing due to a shortage of the amount of the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group. Therefore, it is preferable that the alicyclic structure-containing monomer is contained as a monomer unit constituting the polymer in an amount of 35% by mass or less, particularly preferably 30% by mass or less, and further 20% by mass or less. preferable. When the content of the alicyclic structure-containing monomer is within the above range, the above electrolytic solution resistance becomes more excellent.

  If desired, the (meth) acrylic acid ester polymer (A) may contain other monomer as a monomer unit constituting the polymer. The other monomer may be a monomer containing a reactive functional group (excluding a carboxy group) or a monomer not containing a reactive functional group.

  Examples of the monomer having a reactive functional group include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer) and a monomer having an amino group in the molecule (amino group-containing monomer).

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and (meth ) Examples include hydroxyalkyl esters of (meth) acrylic acid such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. These may be used alone or in combination of two or more.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. These may be used alone or in combination of two or more.

  In addition, in order not to inhibit the effect obtained by the crosslinked structure by the reaction of the carboxy group and the metal chelate-based crosslinking agent (B), the monomer containing the reactive functional group is only the above-mentioned carboxy group-containing monomer. Preferably.

  On the other hand, examples of the monomer that does not contain a reactive functional group include a carbon of an alkyl group such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. (Meth) acrylic acid alkoxyalkyl ester such as (meth) acrylic acid alkyl ester having a number of 1 to 4, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, etc., (meth) acrylic acid N, N- (Meth) acrylic acid ester having non-crosslinkable tertiary amino group such as dimethylaminoethyl, N, N-dimethylaminopropyl (meth) acrylate, (meth) acryloylmorpholine, (meth) acrylamide, dimethylacrylamide, acetic acid Examples thereof include vinyl and styrene. These may be used alone or in combination of two or more.

  The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

  The lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 50,000 or more, more preferably 100,000 or more, and particularly preferably 200,000 or more. Is preferably 500,000 or more. When the lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is at least the above, the elution resistance of the obtained pressure-sensitive adhesive to the electrolytic solution becomes more excellent.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 2.5 million or less as an upper limit, more preferably 2 million or less, and particularly preferably 1.5 million or less. Further, it is preferably 1.2 million or less. When the upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above, the adhesive force of the obtained pressure-sensitive adhesive becomes more excellent. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  The upper limit of the glass transition temperature (Tg) of the (meth) acrylic acid ester polymer (A) is preferably lower than 20 ° C, particularly preferably lower than 0 ° C, and further lower than -40 ° C. Preferably. When the upper limit of the glass transition temperature of the (meth) acrylic acid ester polymer (A) is above, the tackiness of the pressure-sensitive adhesive at room temperature is high, and the adhesive will not easily peel off when immersed in the electrolytic solution. On the other hand, the lower limit of the glass transition temperature (Tg) of the (meth) acrylic acid ester polymer (A) is not particularly limited, but is usually −70 ° C. or higher from the viewpoint of improving durability in the electrolytic solution. It is preferably at least -62.5 ° C, more preferably at least -55 ° C. Here, the glass transition temperature (Tg) of the (meth) acrylic acid ester polymer (A) is the glass transition temperature (Tg) as a homopolymer of each monomer constituting the (meth) acrylic acid ester polymer (A). Based on the above, it is assumed to be calculated by the FOX formula.

  In addition, in the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used alone or in combination of two or more kinds.

(1-2) Metal chelate crosslinking agent (B)
The adhesive composition P preferably contains a metal chelate-based crosslinking agent (B). When the adhesive composition P contains the metal chelate-based crosslinking agent (B), a pressure-sensitive adhesive obtained by crosslinking the (meth) acrylic acid ester polymer (A) with the metal chelate-based crosslinking agent (B) is obtained. The pressure-sensitive adhesive having this crosslinked structure has a high resistance to an electrolytic solution, particularly a non-aqueous electrolytic solution, and is combined with the electrolytic solution resistance of the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group to form an electrolytic solution. It becomes difficult to elute with the liquid.

  As the metal chelate-based cross-linking agent (B), a metal chelate compound whose metal atom is aluminum, zirconium, titanium, zinc, iron, tin or the like can be used. Of these, aluminum chelate compounds are particularly preferable. The aluminum chelate compound exhibits the above-mentioned elution resistance to the electrolytic solution particularly effectively.

  Examples of the aluminum chelate compound include diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bisoleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetoacetate, diisopropoxy aluminum monolauryl acetoacetate, diisopropoxy. Aluminum monostearyl acetoacetate, diisopropoxy aluminum monoisostearyl acetoacetate, monoisopropoxy aluminum mono-N-lauroyl-β-alanate monolauryl acetoacetate, aluminum tris (acetylacetonate), monoacetylacetonate aluminum bis ( Isobutyl acetoacetate) chelate, monoacetylacetonate aluminum Umubisu (2-ethylhexyl acetoacetate) chelate, monoacetylacetonate aluminum bis (dodecyl acetoacetate) chelate, monoacetylacetonate aluminum bis (oleyl acetoacetate) chelate, and the like. Among these, aluminum tris (acetylacetonate) is preferable from the viewpoint of the above effects. These may be used alone or in combination of two or more.

  Examples of other metal chelate compounds include titanium tetrapropionate, titanium tetra-n-butyrate, titanium tetra-2-ethylhexanoate, zirconium sec-butyrate, zirconium diethoxy-tert-butyrate, triethanol. Examples include amine titanium dipropionate, ammonium salt of titanium lactate, and tetraoctylene glycol titanate. These may be used alone or in combination of two or more.

  The above metal chelate-based cross-linking agents (B) may be used alone or in combination of two or more.

  The content of the metal chelate-based cross-linking agent (B) in the pressure-sensitive adhesive composition P according to the present embodiment is 0.1 mass% as a lower limit with respect to 100 mass parts of the (meth) acrylic acid ester polymer (A). It is preferably not less than 0.3 part by mass, more preferably not less than 0.3 part by mass, particularly preferably not less than 0.5 part by mass, more preferably not less than 1.2 parts by mass. Further, the content of the metal chelate-based cross-linking agent (B) is preferably 5 parts by mass or less as an upper limit, particularly preferably 4 parts by mass or less, and further preferably 3 parts by mass or less. .. When the content of the metal chelate-based cross-linking agent (B) is within the above range, the above-mentioned effect becomes more excellent.

(1-3) Silane coupling agent (C)
It is preferable that the adhesive composition P further contains a silane coupling agent (C). When the pressure-sensitive adhesive composition P contains the silane coupling agent (C), even when the pressure-sensitive adhesive sheet for a battery is in contact with the electrolytic solution (including when it is immersed), it can be adhered to an adherend (particularly a metal member). (Excellent) exhibits excellent tackiness. Thereby, the superposition | adhesion effect with the adhesiveness and electrolytic solution resistance by the (meth) acrylic acid alkyl ester whose carbon number of the alkyl group which comprises a (meth) acrylic acid ester polymer (A) is 6-20 is demonstrated. As a result, the adhesive strength is further improved, and peeling of the battery adhesive sheet from the adherend is effectively suppressed. As a result, the decrease in battery performance due to the battery pressure-sensitive adhesive sheet is suppressed. Further, even when the hard coat layer is formed on the surface of the pressure-sensitive adhesive sheet for a battery on the side of the pressure-sensitive adhesive layer of the substrate, the pressure-sensitive adhesive layer has high adhesion to the hard coat layer. Therefore, it is possible to prevent peeling or the like from occurring at the interface between the hard coat layer and the pressure-sensitive adhesive layer by immersing the battery pressure-sensitive adhesive sheet in the electrolytic solution, and to increase the adhesive strength after immersion in the electrolytic solution solvent. .. Further, when the release sheet is peeled from the pressure-sensitive adhesive layer, it is possible to prevent the pressure-sensitive adhesive layer from transferring to the release sheet and peeling from the hard coat layer.

  The silane coupling agent (C) is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule and having good compatibility with the (meth) acrylic acid ester polymer (A).

  Examples of the silane coupling agent (C) include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, mercapto groups such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and 3-mercaptopropyldimethoxymethylsilane Containing silicon groups, amino groups such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane Silicon compound, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one of these, and an alkyl group such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, or ethyltrimethoxysilane Examples thereof include condensates with silicon compounds. Among these, a silicon compound having an epoxy structure is preferable, and 3-glycidoxypropyltrimethoxysilane is particularly preferable, from the viewpoint of the above effects. These may be used alone or in combination of two or more.

  The content of the silane coupling agent (C) in the adhesive composition P is preferably 0.01 parts by mass or more, based on 100 parts by mass of the (meth) acrylic acid ester polymer (A), and 0 The amount is more preferably 0.05 part by mass or more, particularly preferably 0.1 part by mass or more, and further preferably 0.4 part by mass or more. Further, the content is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, particularly preferably 3 parts by mass or less, and further preferably 1.5 parts by mass or less. Is preferred. When the content of the silane coupling agent (C) is in the above range, the adhesive strength after immersion in the electrolytic solution solvent becomes more excellent.

(1-4) Various additives To the adhesive composition P, if desired, various additives commonly used for acrylic pressure-sensitive adhesives such as tackifiers, antioxidants, softeners, and fillers are added. can do. In addition, the below-mentioned polymerization solvent and diluent solvent are not included in the additives constituting the adhesive composition P.

(2) Production of pressure-sensitive adhesive composition The pressure-sensitive adhesive composition P was produced by producing the (meth) acrylic acid ester polymer (A), and the obtained (meth) acrylic acid ester polymer (A) was optionally mixed with It can be produced by adding a metal chelate crosslinking agent (B), a silane coupling agent (C), an additive and the like.

  The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator if desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane1-carbonitrile), 2 , 2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate) , 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,2'-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxy. Dicarbonate, t-butyl peroxy neodecanoate, t-butyl peroxy vivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like can be mentioned.

  In the polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

  When the (meth) acrylic acid ester polymer (A) is obtained, a solution of the (meth) acrylic acid ester polymer (A) is optionally mixed with a metal chelate-based crosslinking agent (B), a silane coupling agent (C), The adhesive composition P is obtained by adding an additive etc. and mixing them sufficiently.

  The pressure-sensitive adhesive composition P is appropriately diluted with a diluting solvent or the like in addition to the above-mentioned polymerization solvent in order to adjust the viscosity to an appropriate level for coating or to adjust the pressure-sensitive adhesive layer to a desired thickness. It may be a coating liquid described later. Examples of the diluent solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and two or more kinds may be used in combination.

[Battery adhesive sheet]
A battery pressure-sensitive adhesive sheet according to an embodiment of the present invention includes a base material and a pressure-sensitive adhesive layer laminated on one surface side of the base material, and the pressure-sensitive adhesive layer is formed from the above-mentioned pressure-sensitive adhesive composition P. It was formed. Hereinafter, the pressure-sensitive adhesive sheet for battery according to the preferred embodiment will be described.

  As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 for battery according to the present embodiment includes a base material 11, a hard coat layer 12 provided on one surface side of the base material 11, and the base material 11 in the hard coat layer 12. The pressure-sensitive adhesive layer 13 is provided on the side opposite to and the release sheet 14 provided on the side of the pressure-sensitive adhesive layer 13 opposite to the hard coat layer 12. The pressure-sensitive adhesive layer 13 is formed from the pressure-sensitive adhesive composition P described above. In the present invention, the hard coat layer 12 and the release sheet 14 are not essential constituent elements and may be omitted.

  The battery pressure-sensitive adhesive sheet 1 having the pressure-sensitive adhesive layer 13 formed from the above-mentioned pressure-sensitive adhesive composition P has a (meth) acrylic acid ester polymer even when it is in contact with the electrolytic solution (including when it is immersed). The good adhesion and electrolytic solution resistance of the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group constituting (A) suppresses cohesive failure of the pressure-sensitive adhesive layer 13 due to swelling. The battery pressure-sensitive adhesive sheet 1 exhibits excellent adhesion to the adherend. In addition, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 13 is less likely to be eluted in the electrolytic solution, and the pressure-sensitive adhesive does not adversely affect the battery performance. As a result, malfunction of the battery, thermal runaway, and short circuit due to the battery adhesive sheet 1 are suppressed.

  Further, the battery pressure-sensitive adhesive sheet 1 according to the present embodiment is provided with the hard coat layer 12, so that the insulating property can be secured even when the base material 11 and the pressure-sensitive adhesive layer 13 are carbonized. Can improve the safety of.

1. Base Material In the pressure-sensitive adhesive sheet 1 for battery according to the present embodiment, the base material 11 preferably has flame retardancy satisfying the flame retardancy level V-0 of UL94 standard. Since the base material 11 has such flame retardancy, the base material 11 is prevented from being denatured or deformed even when heat is generated by using a normal battery. In addition, even if a battery malfunctions and generates excessive heat, ignition and combustion of the base material 11 are suppressed, and a serious accident is prevented.

  The material of the base material 11 can be appropriately selected from the viewpoints of flame retardancy, heat resistance, insulation, reactivity with an electrolytic solution, permeability of the electrolytic solution, and the like. In particular, it is preferable to use a resin film as the base material 11. As the resin film, for example, polyethylene terephthalate, polybutylene terephthalate, polyester film such as polyethylene naphthalate, polyethylene film, polyolefin film such as polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, poly Vinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyether Imide film, fluororesin film, polyamide Resins such as films, polyimide films, polyamideimide films, acrylic resin films, polyurethane resin films, norbornene-based polymer films, cyclic olefin-based polymer films, cyclic conjugated diene-based polymer films, vinyl alicyclic hydrocarbon polymer films, etc. A film or a laminated film thereof can be used. In particular, from the viewpoint of exhibiting excellent flame retardancy and heat resistance, a polymer film containing nitrogen in the main chain (a component other than the polymer may be contained; the same in the present specification) is preferable, In particular, a polymer film having a nitrogen-containing ring structure in its main chain is preferable, and a polymer film having a nitrogen-containing ring structure and an aromatic ring structure in its main chain is more preferable. Specifically, for example, a polyimide film, a polyetherimide film or a polyetheretherketone film is preferable, and among these, a polyimide film showing higher heat resistance is preferable.

  The thickness of the substrate 11 is preferably 5 to 200 μm, particularly preferably 10 to 100 μm, and further preferably 15 to 40 μm. When the thickness of the base material 11 is 5 μm or more, the base material 11 is provided with appropriate rigidity, and even when curing shrinkage occurs when the hard coat layer 12 is formed on the base material 11, curl Outbreak is effectively suppressed. In addition, since the thickness of the base material 11 is 200 μm or less, the pressure-sensitive adhesive sheet 1 for battery has appropriate flexibility, and a surface having a step exists as in the case of fixing the electrode and the electrode lead-out tab. Even when the battery pressure-sensitive adhesive sheet 1 is attached, the step can be appropriately followed.

2. Hard Coat Layer (1) Physical Properties of Hard Coat Layer In the pressure-sensitive adhesive sheet 1 for battery according to the present embodiment, the hard coat layer 12 in the state of being provided on the base material 11 is 250 g / cm 2 using # 0000 steel wool. It is preferable that the hard coat layer 12 is rubbed 10 cm back and forth 10 times with a load of ² to prevent scratches. With such an evaluation of steel wool resistance, the permeation of the electrolytic solution through the hard coat layer 12 is effectively blocked, and the escape of the inorganic filler due to the swelling of the hard coat layer 12 is effectively suppressed.

(2) Composition of Hard Coat Layer The hard coat layer 12 is preferably formed from a composition containing an organic component and an inorganic filler (hereinafter sometimes referred to as “composition for hard coat layer”). In particular, the hard coat layer 12 is preferably made of a material obtained by curing a composition containing an active energy ray-curable component and an inorganic filler.

(2-1) Active energy ray-curable component The active energy ray-curable component is not particularly limited as long as it is cured by irradiation with an active energy ray and exhibits a desired hardness.

  Specific examples of the active energy ray-curable component include a polyfunctional (meth) acrylate-based monomer, a (meth) acrylate-based prepolymer, and an active energy ray-curable polymer. Among them, the polyfunctional (meth) acrylate is particularly preferable. It is preferably a system monomer and / or a (meth) acrylate prepolymer. The polyfunctional (meth) acrylate-based monomer and the (meth) acrylate-based prepolymer may be used alone or in combination. In addition, in this specification, (meth) acrylate means both an acrylate and a methacrylate. The same applies to other similar terms.

  Examples of the polyfunctional (meth) acrylate-based monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (Meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified phosphoric acid di (meth) acrylate, allylated Cyclohexyldi (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentae Thritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, propionic acid modified dipentaerythritol penta (meth) acrylate, dipentaerythritol Hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and other polyfunctional (meth) acrylates may be mentioned. These may be used alone or in combination of two or more. The polyfunctional (meth) acrylate-based monomer is not particularly limited, but it is more preferable that it has a molecular weight of less than 1000 from the viewpoint of preventing the inorganic filler from escaping from the hard coat layer 12 when immersed in the electrolytic solution.

  On the other hand, examples of the (meth) acrylate-based prepolymer include polyester acrylate-based, epoxy acrylate-based, urethane acrylate-based, and polyol acrylate-based prepolymers. The prepolymer may be used alone or in combination of two or more.

  The active energy ray-curable component constituting the hard coat layer 12 of the present embodiment has a glass transition point after curing of preferably 130 ° C. or higher, more preferably 150 ° C. or higher, and a glass transition point is observed. It is particularly preferable that it is not. When the glass transition point of the active energy ray-curable component is as described above, the heat resistance of the hard coat layer 12 becomes excellent, and the battery pressure-sensitive adhesive sheet 1 including such a hard coat layer 12 is included. The battery performance and safety are also excellent.

  When two or more active energy ray-curable components are used in the hard coat layer 12 of the present embodiment, it is preferable that the active energy ray-curable components have excellent compatibility with each other.

(2-2) Inorganic Filler The hard coat layer composition that constitutes the hard coat layer 12 of the present embodiment preferably contains an inorganic filler. By containing the inorganic filler, rigidity is imparted to the hard coat layer 12 of the present embodiment, and the battery adhesive sheet 1 is ruptured or punctured due to impact or the like under high temperature or immersion in an electrolytic solution. Can be prevented.

  Preferred inorganic fillers include powders of silica, alumina, boehmite, talc, calcium carbonate, titanium oxide, iron oxide, silicon carbide, boron nitride, zirconium oxide and the like, spherical beads of these, single crystal fibers and glass fibers. These may be used alone or in admixture of two or more. Among these, silica, alumina, boehmite, titanium oxide, zirconium oxide and the like are preferable, and silica, alumina and zirconium oxide are preferable from the viewpoint of dispersibility in the active energy ray-curable component. It should be noted that these inorganic fillers can also be used in the form of a sol dispersed in a dispersion medium.

  The inorganic filler is also preferably surface-modified. Reactive silica can be illustrated as such an inorganic filler.

  In the present specification, "reactive silica" refers to silica fine particles surface-modified with an organic compound having an active energy ray-curable unsaturated group. The silica fine particles (reactive silica) surface-modified with an organic compound having an active energy ray-curable unsaturated group, for example, usually have a silanol group on the silanol group on the surface of the silica fine particles having an average particle size of 1 to 200 nm. It can be obtained by reacting an active energy ray-curable unsaturated group-containing organic compound having a reactive functional group (eg, isocyanate group, epoxy group, carboxy group, etc.). As the active energy ray-curable unsaturated group, a (meth) acryloyl group or a vinyl group can be preferably cited.

  As an organic-inorganic hybrid material (organo silica sol) containing such reactive silica and the above-mentioned polyfunctional (meth) acrylate-based monomer and / or (meth) acrylate-based prepolymer, for example, trade name "OPSTAR Z7530" , "OPSTAR Z7524", "OPSTAR TU4086", "OPSTAR Z7537" (above, manufactured by JSR Corporation) and the like can be used.

  Other examples of preferable inorganic fillers include alumina ceramic nanoparticles, silica sol in which silica fine particles in which the silanol groups on the silica surface are exposed in a colloidal state in a dispersion medium, and silanol groups on the silica surface are subjected to silane coupling. Examples thereof include organosilica sol surface-treated with an agent or the like.

  The inorganic filler used in the present embodiment preferably has an average particle diameter of 1 to 1000 nm, particularly preferably 10 to 500 nm, and further preferably 15 to 200 nm. When the average particle size of the inorganic filler is 1 nm or more, the hard coat layer 12 obtained by curing the composition for hard coat layer has higher rigidity. When the average particle size of the inorganic filler is 1000 nm or less, the dispersibility of the inorganic filler in the composition for hard coat layer becomes excellent, and when the hard coat layer 12 is formed on the substrate 11, It is possible to effectively prevent the occurrence of unevenness on the surface of the hard coat layer 12 on the side opposite to the substrate 11. Furthermore, by forming the pressure-sensitive adhesive layer 13 on the surface, very high smoothness can be obtained on the surface of the pressure-sensitive adhesive layer 13 opposite to the hard coat layer 12. Thereby, the pressure-sensitive adhesive layer 13 can exhibit excellent adhesion to the adherend. The average particle size of the inorganic filler is measured by a laser diffraction / scattering particle size distribution measuring device.

  The content of the inorganic filler in the hard coat layer 12 of the present embodiment is preferably 0 to 90 mass% (90 mass% or less) with respect to the hard coat layer 12, and more preferably 30 to 85 mass%. It is particularly preferably 40 to 80% by mass, and further preferably 45 to 70% by mass. When the content of the inorganic filler is 30% by mass or more, the rigidity imparted to the hard coat layer 12 becomes higher. On the other hand, when the content of the inorganic filler is 90% by mass or less, the layer formation using the composition for hard coat layer becomes easy.

(2-3) Other components The composition for forming the hard coat layer 12 of the present embodiment may contain various additives in addition to the components described above. Examples of various additives include photopolymerization initiators, antioxidants, antistatic agents, silane coupling agents, antioxidants, thermal polymerization inhibitors, colorants, surfactants, storage stabilizers, plasticizers, lubricants. , Antifoaming agents, organic fillers and the like.

  When ultraviolet rays are used as the active energy rays to form the hard coat layer 12, it is preferable to use a photopolymerization initiator. The photopolymerization initiator is not particularly limited as long as it functions as a photopolymerization initiator of the active energy ray-curable component to be used, but for example, acylphosphine oxide compounds, benzoin compounds, acetophenone compounds, titanocene compounds, thioxanthone. Examples thereof include compounds and peroxide compounds. Specifically, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethan-1-one, benzoin, benzoin Examples include methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl diphenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone. These may be used alone or in combination of two or more.

  The content of the photopolymerization initiator in the composition for the hard coat layer is usually preferably 0.1 to 20 parts by mass, and particularly preferably 1 to 20 parts by mass with respect to 100 parts by mass of the active energy ray-curable component. It is preferably 15 parts by mass.

(3) Thickness of Hard Coat Layer The thickness of the hard coat layer 12 is preferably 0.1 to 10 μm, particularly preferably 0.5 to 7 μm, and further preferably 1 to 4 μm. preferable. When the thickness of the hard coat layer 12 is 0.1 μm or more, the permeation of the hard coat layer 12 by the electrolytic solution is effectively blocked. In addition, since the thickness of the hard coat layer 12 is 10 μm or less, the battery pressure-sensitive adhesive sheet 1 has appropriate flexibility, and a surface having a step as in the case of fixing the electrode and the electrode extraction tab. Even when the battery pressure-sensitive adhesive sheet 1 is attached to the battery, the battery pressure-sensitive adhesive sheet 1 can properly follow the step.

3. Adhesive layer The adhesive layer 13 is formed from the above-mentioned adhesive composition P. The method for forming the pressure-sensitive adhesive layer 13 will be described later.

(1) Physical Properties of Adhesive / Adhesive Layer In the battery adhesive sheet 1 according to the present embodiment, the adhesive constituting the adhesive layer 13 is adhered after being immersed in the solvent of the non-aqueous electrolyte solution at 80 ° C. for 72 hours. The lower limit of the gel fraction of the agent is preferably 70% or more, particularly preferably 80% or more, and further preferably 90% or more. When the lower limit of the gel fraction is the above, the elution amount of the pressure-sensitive adhesive when the pressure-sensitive adhesive layer 13 comes into contact with the electrolytic solution can be suppressed low. Thereby, malfunction, thermal runaway, and short circuit of the battery using the battery adhesive sheet 1 can be suppressed more effectively.

  On the other hand, the upper limit of the gel fraction is preferably 100% or less, particularly preferably 99% or less, and further preferably 98% or less. When the upper limit of the gel fraction is 98% or less, the battery pressure-sensitive adhesive sheet 1 has appropriate flexibility, and the battery has a step on the surface where a step exists, as in the case of fixing the electrode and the electrode extraction tab. Even when the pressure-sensitive adhesive sheet 1 is attached, the step can be appropriately followed.

  In addition, the solvent of the non-aqueous electrolyte solution here is a preparation solution in which ethylene carbonate and diethyl carbonate are mixed at a volume ratio of 1: 1 and the gel fraction test method is as shown in the test example described later. ..

(2) Thickness of pressure-sensitive adhesive layer The thickness of the pressure-sensitive adhesive layer 13 (value measured according to JIS K7130) is preferably 1 to 50 μm, particularly preferably 3 to 15 μm, and further 4 It is preferably ˜9 μm. When the thickness of the pressure-sensitive adhesive layer 13 is 1 μm or more, the pressure-sensitive adhesive sheet 1 for battery can exhibit more excellent adhesion. Moreover, since the thickness of the pressure-sensitive adhesive layer 13 is 50 μm or less, it is possible to effectively reduce the amount of the electrolytic solution entering from the end of the pressure-sensitive adhesive layer 13.

4. Release Sheet The release sheet 14 protects the adhesive layer until the battery adhesive sheet 1 is used, and is released when the battery adhesive sheet 1 is used. In the battery pressure-sensitive adhesive sheet 1 according to the present embodiment, the release sheet 14 is not always necessary.

  Examples of the release sheet 14 include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film. , Polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin film , A liquid crystal polymer film or the like is used. Further, these crosslinked films are also used. Furthermore, these laminated films may be used.

  The release surface of the release sheet 14 (the surface in contact with the pressure-sensitive adhesive layer 13) is preferably subjected to a release treatment. Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

  The thickness of the release sheet 14 is not particularly limited, but is usually about 20 to 150 μm.

5. Physical Properties of Battery Adhesive Sheet etc. Adhesive strength of the battery adhesive sheet 1 according to the present embodiment with respect to an aluminum plate (adhesive strength before immersion in an electrolyte solvent) is preferably 0.5 N / 25 mm or more as a lower limit, It is more preferably 0.75 N / 25 mm or more, particularly preferably 1.0 N / 25 mm or more, and further preferably 2.0 N / 25 mm or more. Since the lower limit of the adhesive strength of the battery pressure-sensitive adhesive sheet 1 before immersion in the electrolyte solution is the above, the battery pressure-sensitive adhesive sheet 1 is adhered to an adherend (particularly a metal) before the battery pressure-sensitive adhesive sheet 1 contacts the electrolyte solution. It is difficult to cause the problem of peeling from the member). The upper limit of the adhesive strength before immersion in the electrolytic solution solvent is not particularly limited, but is usually preferably 50 N / 25 mm or less, more preferably 40 N / 25 mm or less, and particularly preferably 30 N / 25 mm or less. More preferably, it is preferably 10 N / 25 mm or less. In addition, the adhesive force in this specification basically means the adhesive force measured by a 180 ° peeling method according to JIS Z0237: 2009, and the detailed measuring method is as shown in the test examples described later.

  In addition, the battery pressure-sensitive adhesive sheet 1 according to the present embodiment is attached to an aluminum plate, and after being immersed in a solvent of a non-aqueous electrolyte solution at 80 ° C. for 72 hours, the battery pressure-sensitive adhesive sheet 1 has an adhesive force to the aluminum plate (electrolysis). The lower limit of (adhesive strength after immersion in liquid solvent) is preferably 0.5 N / 25 mm or more, more preferably 0.75 N / 25 mm or more, and particularly preferably 1.0 N / 25 mm or more. Further, it is preferably 2.0 N / 25 mm or more. Since the lower limit of the adhesive strength of the battery pressure-sensitive adhesive sheet 1 after immersion in the electrolytic solution solvent is as described above, the battery pressure-sensitive adhesive sheet 1 can be produced even after the battery pressure-sensitive adhesive sheet 1 is in contact with (immersed in) the electrolytic solution. The problem of peeling from the adherend (particularly the metal member) is unlikely to occur. The upper limit of the adhesive strength after immersion in the electrolytic solution solvent is not particularly limited, but is usually preferably 40 N / 25 mm or less, more preferably 30 N / 25 mm or less, and particularly preferably 20 N / 25 mm or less. More preferably, it is preferably 10 N / 25 mm or less. The battery pressure-sensitive adhesive sheet 1 according to the present embodiment contains the above-mentioned (meth) acrylic acid ester polymer (A), preferably a metal chelate-based cross-linking agent (B), and particularly preferably a silane coupling agent (C). By having the pressure-sensitive adhesive layer 13 formed by using the contained pressure-sensitive adhesive composition P, it is possible to achieve excellent pressure-sensitive adhesive strength in the above range. The solvent of the non-aqueous electrolyte solution here is a preparation solution in which ethylene carbonate and diethyl carbonate are mixed at a volume ratio of 1: 1.

  The adhesive strength after immersion in the electrolytic solution solvent is preferably 50% or more, more preferably 60% or more, and particularly preferably 70% or more, with respect to the adhesive strength before immersion in the electrolytic solution solvent. And more preferably 100% or more.

  The thickness of the pressure-sensitive adhesive sheet 1 for a battery (excluding the thickness of the release sheet 14) is preferably 10 to 250 μm, particularly preferably 15 to 110 μm, and further preferably 20 to 45 μm. When the thickness of the battery pressure-sensitive adhesive sheet 1 is within the above range, the battery pressure-sensitive adhesive sheet 1 becomes more suitable in which both the adhesive strength and the heat resistance are compatible.

6. Method for producing pressure-sensitive adhesive sheet for battery The pressure-sensitive adhesive sheet for battery 1 according to the present embodiment includes, for example, a laminate of the base material 11 and the hard coat layer 12, and a coating film of the adhesive composition P and the release sheet 14. Body is prepared and these laminates are stuck together so that the hard coat layer 12 and the coating film of the adhesive composition P are in contact with each other, and then cured to change the coating film of the adhesive composition P to the adhesive layer. It can be manufactured by forming 13. From the viewpoint of improving the adhesiveness between the hard coat layer 12 and the pressure-sensitive adhesive layer 13, the surface to be bonded of any one of these layers or the surface to be bonded of both layers is subjected to corona treatment, plasma treatment, etc. It is also preferable to carry out the surface treatment of and then bond both layers.

  The laminate of the base material 11 and the hard coat layer 12 can be produced, for example, as follows. First, a coating liquid containing the composition for hard coat layer and optionally a solvent is applied to one main surface of the base material 11 and dried. The application of the coating liquid may be carried out by a conventional method, for example, a bar coating method, a knife coating method, a Meyer bar method, a roll coating method, a blade coating method, a die coating method or a gravure coating method. Drying can be performed by heating, for example, at 80 to 150 ° C. for about 30 seconds to 5 minutes.

After that, the layer formed by drying the coating solution is irradiated with an active energy ray to cure the layer and form the hard coat layer 12. As the active energy ray, for example, an electromagnetic wave or a charged particle beam having an energy quantum can be used, and specifically, an ultraviolet ray, an electron beam or the like can be used. Particularly, ultraviolet rays, which are easy to handle, are preferable. The irradiation of ultraviolet rays can be performed by a high pressure mercury lamp, a xenon lamp, or the like, and the irradiation amount of ultraviolet rays is preferably such that the illuminance is about 50 to 1000 mW / cm ² . Further, the light quantity is preferably 50~10000mJ / cm ^2, more preferably 80~5000mJ / cm ^2, and particularly preferably 200~2000mJ / cm ^2. On the other hand, the electron beam irradiation can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.

  The laminate of the coating film of the adhesive composition P and the release sheet 14 can be produced, for example, as follows. The coating liquid containing the above-mentioned adhesive composition P and, if desired, a solvent is applied to the release surface of the release sheet 14 and heat-treated to form a coating film.

  The above heat treatment can also serve as a drying treatment when volatilizing the diluting solvent of the coating liquid. When heat treatment is performed, the heating temperature is preferably 50 to 150 ° C, and particularly preferably 70 to 120 ° C. Further, the heating time is preferably 30 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

  After the hard coat layer 12 on the base material 11 and the coating film of the adhesive composition P on the release sheet 14 are laminated, curing is performed. This curing is usually performed at room temperature (for example, 23 ° C. and 50% RH) for about 1 to 2 weeks. As a result, the coating film of the pressure-sensitive adhesive composition P becomes the pressure-sensitive adhesive layer 13, and the battery pressure-sensitive adhesive sheet 1 is manufactured.

  As another method for manufacturing the battery pressure-sensitive adhesive sheet 1 according to the present embodiment, the battery pressure-sensitive adhesive sheet 1 may be manufactured by sequentially forming the hard coat layer 12 and the pressure-sensitive adhesive layer 13 on the base material 11.

[Lithium-ion battery]
A lithium ion battery according to an embodiment of the present invention is fixed inside a battery by using the above-mentioned pressure-sensitive adhesive sheet for a battery, in a state where two or more conductors are in contact with each other. It is preferable that at least one of the two or more conductors has a sheet shape and at least one has a linear shape or a tape shape. Hereinafter, a lithium ion battery according to a preferred embodiment will be described.

  As shown in FIG. 2, the lithium-ion battery 2 according to the present embodiment has a bottomed cylindrical outer casing 21 having a bottom portion forming a negative electrode terminal 23, and a positive electrode terminal 22 provided in an opening of the outer casing 21. And an electrode body 24 provided inside the exterior body 21. Further, an electrolytic solution is sealed inside the lithium-ion battery 2.

  The electrode body 24 includes a sheet-shaped (belt-shaped) positive electrode current collector 241 in which a positive electrode active material layer 241a is stacked, a negative electrode current collector 242 in which a negative electrode active material layer 242a layer is stacked, and between them. And an intervening separator 243. Note that the stack of the positive electrode current collector 241 and the positive electrode active material layer 241a may be referred to as a positive electrode, and the stack of the negative electrode current collector 242 and the negative electrode active material layer 242a may be referred to as a negative electrode. It may be called an electrode. The positive electrode, the negative electrode, and the separator 243 are each wound and inserted into the exterior body 21.

  Further, as shown in FIG. 3, a linear or tape-shaped electrode lead-out tab 244 is attached to the positive electrode current collector 241 by the battery adhesive sheet 1 described above. It is electrically connected to the positive electrode current collector 241. The electrode lead-out tab 244 is also electrically connected to the positive electrode terminal 22. The negative electrode current collector 242 is electrically connected to the negative electrode terminal 23 via an electrode lead-out tab (not shown).

  Generally, the positive electrode current collector 241 and the negative electrode current collector 242 are made of a metal such as aluminum, and the electrode lead-out tab 244 is made of a metal such as aluminum or copper.

The electrolytic solution used in the lithium-ion battery 2 is usually a non-aqueous electrolytic solution. As the non-aqueous electrolytic solution, for example, a solution in which a lithium salt as an electrolyte is dissolved in a mixed solvent of a cyclic carbonic acid ester and a lower chain carbonic acid ester is preferably cited. Examples of the lithium salt include fluorine-based complex salts such as lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), and LiN (SO ₂ Rf) ₂ LiC (SO ₂ Rf) ₃ (where Rf = CF ₃ , C ₂ F ₅ ) or the like is used. Further, ethylene carbonate, propylene carbonate, etc. are used as the cyclic carbonic acid ester, and dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, etc. are preferably mentioned as the lower chain carbonic acid ester.

  The lithium-ion battery 2 according to the present embodiment can be manufactured by a usual method except that the battery adhesive sheet 1 described above is used to fix the electrode extraction tab 244.

  In the lithium-ion battery 2 according to this embodiment, the electrode take-out tab 244 is attached to the positive electrode current collector 241 by the battery adhesive sheet 1. Even when the pressure-sensitive adhesive sheet 1 for a battery is immersed in a non-aqueous electrolyte solution, the pressure-sensitive adhesive layer 13 is prevented from cohesively breaking due to swelling, and the positive electrode current collector 241 and the electrode take-out tab 244 can be prevented. Exhibits excellent adhesive strength. Further, the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 13 is hard to be eluted into the electrolytic solution, and the pressure-sensitive adhesive does not adversely affect the battery performance.

  Further, since the battery pressure-sensitive adhesive sheet 1 includes the hard coat layer 12, even if the base material 11 and the pressure-sensitive adhesive layer 13 are carbonized, the insulating property can be ensured.

  From the above, the lithium-ion battery 2 according to the present embodiment is suppressed in performance deterioration, malfunction, thermal runaway, and short circuit due to the battery adhesive sheet 1, and has a high temperature even under conditions of large current. It is expected to have excellent stability and safety.

  The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-described embodiment is intended to include all design changes and equivalents within the technical scope of the present invention.

  For example, in the battery pressure-sensitive adhesive sheet 1, the hard coat layer 12 and / or the release sheet 14 may be omitted. Further, in the battery pressure-sensitive adhesive sheet 1, another layer may be provided between the base material 11 and the hard coat layer 12.

  Hereinafter, the present invention will be described more specifically with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
1. Formation of Hard Coat Layer on Substrate 40 parts by mass of dipentaerythritol hexaacrylate (material whose glass transition point is not observed after curing) as an active energy ray-curable component, and 5 parts by mass of hydroxycyclohexyl phenyl ketone as a photopolymerization initiator Parts and organosilica sol as an inorganic filler (manufactured by NISSAN CHEMICAL CO., LTD., Trade name "MEK-ST"; average particle size 30 nm) 60 parts by mass (solid content conversion value; the same applies hereinafter), and diluting with methyl ethyl ketone Thus, a coating solution for hard coat layer was prepared.

After coating the coating solution with a knife coater on one surface of a polyimide film (manufactured by Toray DuPont, trade name “Kapton 100H”, thickness 25 μm, flame retardancy level V-0 of UL94 standard) as a substrate, It was dried at 70 ° C. for 1 minute. Next, the coating film was cured by irradiating the coating film with ultraviolet rays (illuminance: 230 mW / cm ² , light amount: 510 mJ / cm ² ). As a result, a first laminate was obtained in which a hard coat layer having a thickness of 2 μm was formed on one surface of the base material.

In the obtained first laminate, as a steel wool resistance test, # 0000 steel wool was used, and the surface of the hard coat layer was rubbed back and forth 10 cm for 10 cm under a load of 250 g / cm ² . As a result, it was confirmed that scratches due to steel wool were not formed on the surface of the hard coat layer.

2. Formation of Coating Film of Adhesive Composition on Release Sheet 80 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of isobornyl acrylate and 5 parts by mass of acrylic acid are copolymerized by a solution polymerization method to obtain (meth) acrylic acid ester. A polymer (Tg: -50 ° C) was prepared. When the molecular weight of this polymer was measured by gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000.

  Next, 100 parts by mass of the obtained (meth) acrylic acid ester polymer and aluminum tris (acetylacetonate) as a metal chelate crosslinking agent (manufactured by Soken Chemical Industry Co., Ltd., trade name "M-5A") 1.55 Adhesion is achieved by mixing parts by mass with 0.5 parts by mass of 3-glycidoxypropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") as a silane coupling agent, and diluting with methyl ethyl ketone. A coating liquid for the agent layer was prepared.

  The obtained coating liquid was applied to the release-treated surface of a release sheet (manufactured by Lintec Co., Ltd., trade name "PET251130") obtained by subjecting one side of a polyethylene terephthalate film to a release treatment with a silicone-based release agent with a knife coater and then at 1 Heat treatment was performed for a minute. As a result, a second laminate was obtained in which the coating film of the adhesive composition was laminated on the release-treated surface of the release sheet.

3. Preparation of pressure-sensitive adhesive sheet for battery Laminated surface of hard coat layer of first laminate prepared as described above and surface of second laminate prepared as described above on coating film side of adhesive composition Then, it was cured at 23 ° C. and 50% RH for 7 days. As a result, a pressure-sensitive adhesive sheet for batteries was obtained in which the coating film of the pressure-sensitive adhesive composition became a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer had a thickness of 7 μm. The thickness of the pressure-sensitive adhesive layer was calculated by obtaining the total thickness of the battery pressure-sensitive adhesive sheet and subtracting the thicknesses of the first laminate and the release sheet from the total thickness.

[Example 2]
75 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of isobornyl acrylate and 5 parts by mass of acrylic acid were copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (Tg: -44 ° C). When the molecular weight of this polymer was measured by gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A battery pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer obtained above was used as the (meth) acrylic acid ester polymer.

[Example 3]
70 parts by mass of 2-ethylhexyl acrylate, 25 parts by mass of isobornyl acrylate and 5 parts by mass of acrylic acid were copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (Tg: -38 ° C). When the molecular weight of this polymer was measured by gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A battery pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer obtained above was used as the (meth) acrylic acid ester polymer.

[Example 4]
87.5 parts by mass of 2-ethylhexyl acrylate, 7.5 parts by mass of isobornyl acrylate and 5 parts by mass of acrylic acid are copolymerized by a solution polymerization method to obtain a (meth) acrylic acid ester polymer (Tg: −58 ° C.). Was prepared. When the molecular weight of this polymer was measured by gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A battery pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer obtained above was used as the (meth) acrylic acid ester polymer.

[Example 5]
79 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of isobornyl acrylate and 1 part by mass of acrylic acid were copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (Tg: -49 ° C). When the molecular weight of this polymer was measured by gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A battery pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer obtained above was used as the (meth) acrylic acid ester polymer.

[Example 6]
80 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of cyclohexyl acrylate and 5 parts by mass of acrylic acid were copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (Tg: −55 ° C.). When the molecular weight of this polymer was measured by gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A battery pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer obtained above was used as the (meth) acrylic acid ester polymer.

[Example 7]
80 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of n-dodecyl acrylate and 5 parts by mass of acrylic acid are copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (Tg: −28 ° C.). did. When the molecular weight of this polymer was measured by gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A battery pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer obtained above was used as the (meth) acrylic acid ester polymer.

[Example 8]
95 parts by mass of 2-ethylhexyl acrylate and 5 parts by mass of acrylic acid were copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (Tg: -65 ° C). When the molecular weight of this polymer was measured by gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A battery pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the (meth) acrylic acid ester polymer obtained above was used as the (meth) acrylic acid ester polymer.

[Comparative Example 1]
60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized by a solution polymerization method to obtain a (meth) acrylic acid ester polymer (Tg: -38 ° C). Was prepared. When the molecular weight of this polymer was measured using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 500,000.

  Next, 100 parts by mass of the obtained (meth) acrylic acid ester polymer and aluminum tris (acetylacetonate) as a metal chelate crosslinking agent (manufactured by Soken Chemical Industry Co., Ltd., trade name "M-5A") 0.93 Adhesion is achieved by mixing parts by mass with 0.5 parts by mass of 3-glycidoxypropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") as a silane coupling agent, and diluting with methyl ethyl ketone. A coating liquid for the agent layer was prepared. A pressure-sensitive adhesive sheet for a battery was manufactured in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive layer coating liquid was used as the pressure-sensitive adhesive layer coating liquid.

[Comparative Example 2]
76.8 parts by mass of n-butyl acrylate, 19.2 parts by mass of methyl acrylate and 4 parts by mass of acrylic acid are copolymerized by a solution polymerization method to obtain a (meth) acrylic acid ester polymer (Tg: -40 ° C) Was prepared. When the molecular weight of this polymer was measured using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 1,000,000.

  Next, 100 parts by mass of the obtained (meth) acrylic acid ester polymer and aluminum tris (acetylacetonate) as a metal chelate cross-linking agent (manufactured by Soken Chemical Industry Co., Ltd., trade name "M-5A") 0.31 Parts by mass, 2.35 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem Co., Ltd., trade name "BHS8515") as an isocyanate crosslinking agent, and 3-glycidoxypropylmethyldimethoxysilane (as a silane coupling agent) 0.5 part by mass of Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") was mixed and diluted with methyl ethyl ketone to prepare a coating liquid for adhesive layer. A pressure-sensitive adhesive sheet for a battery was manufactured in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive layer coating liquid was used as the pressure-sensitive adhesive layer coating liquid.

[Comparative Example 3]
96 parts by mass of n-butyl acrylate and 4 parts by mass of acrylic acid were copolymerized by a solution polymerization method to prepare a (meth) acrylic acid ester polymer (Tg: -50 ° C). When the molecular weight of this polymer was measured using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 1,000,000.

  Next, 100 parts by mass of the obtained (meth) acrylic acid ester polymer and aluminum tris (acetylacetonate) as a metal chelate crosslinking agent (manufactured by Soken Chemical Industry Co., Ltd., trade name "M-5A") 0.93 Adhesion is achieved by mixing parts by mass with 0.5 parts by mass of 3-glycidoxypropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") as a silane coupling agent, and diluting with methyl ethyl ketone. A coating liquid for the agent layer was prepared. A pressure-sensitive adhesive sheet for a battery was manufactured in the same manner as in Example 1 except that the obtained pressure-sensitive adhesive layer coating liquid was used as the pressure-sensitive adhesive layer coating liquid.

Here, the above-mentioned weight average molecular weight (Mw) is a standard polystyrene equivalent weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
-GPC measuring device: HLC-8020 manufactured by Tosoh Corporation
-GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (x2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C

[Test Example 1] (Measurement of gel fraction by immersion in electrolyte solution)
In the production of the pressure-sensitive adhesive sheets for batteries of Examples and Comparative Examples, a release sheet obtained by subjecting the surface of the second laminate to the coating composition of the pressure-sensitive adhesive composition and one side of the polyethylene terephthalate film to release treatment with a silicone-based release agent (Lintec A peeling-treated surface of a product name "PET251130" manufactured by the company) was attached. Then, it was aged at 23 ° C. and 50% RH for 7 days to obtain a measurement sheet consisting of a pressure-sensitive adhesive layer alone whose both surfaces were protected by a release sheet.

  The obtained measurement sheet is cut into a size of 80 mm x 80 mm, the release sheet that protects both sides of the adhesive layer is peeled off, wrapped in a polyester mesh (mesh size 200), and the mass is weighed with a precision balance. The mass of the pressure-sensitive adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M1. Next, the pressure-sensitive adhesive wrapped in the polyester mesh was dipped in a preparation liquid, which was a mixture of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 as an electrolytic solution solvent, at 80 ° C. for 72 hours. After that, the pressure-sensitive adhesive layer is taken out and once immersed in ethanol to dissolve and remove the attached electrolyte solvent, and then air-dry for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and then an oven at 80 ° C. It was dried inside for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the mesh alone was subtracted to calculate the mass of the adhesive alone. The mass at this time is M2. The gel fraction (%) was calculated from the formula of (M2 / M1) × 100. The results are shown in Table 1.

[Test Example 2] (Measurement of adhesive strength before immersion in electrolyte solvent)
The adhesive strength of the battery pressure-sensitive adhesive sheet according to this test example was measured according to JIS Z0237: 2009, except for the following operations.

  The adhesive sheets for batteries obtained in Examples and Comparative Examples were cut into a width of 25 mm and a length of 250 mm, and then the release sheet was peeled off to obtain test pieces. The exposed pressure-sensitive adhesive layer of this test piece was attached to an aluminum plate as an adherend using a 2 kg rubber roller in an environment of 23 ° C. and 50% RH. Immediately thereafter, using a universal tensile tester (manufactured by Orientec Co., Ltd., trade name "Tensilon UTM-4-100"), the test piece is peeled from the aluminum plate at a peeling angle of 180 ° and a peeling speed of 300 mm / min. The adhesive force (N / 25 mm) was measured by. This measured value was taken as the adhesive strength before immersion in the electrolytic solution solvent. The results are shown in Table 1.

[Test Example 3] (Measurement of adhesive strength after immersion in electrolyte solvent)
The adhesive strength of the battery pressure-sensitive adhesive sheet according to this test example was measured according to JIS Z0237: 2009, except for the following operations.

  The adhesive sheets for batteries obtained in Examples and Comparative Examples were cut into a width of 25 mm and a length of 250 mm, and then the release sheet was peeled off to obtain test pieces. The exposed adhesive layer of this test piece was attached to an aluminum plate as an adherend using a 2 kg rubber roller in an environment of 23 ° C. and 50% RH, and then left in the same environment for 20 minutes. Then, with the test piece attached to an aluminum plate, the test solution was immersed in a prepared solution, in which ethylene carbonate and diethyl carbonate were mixed at a volume ratio of 1: 1 as an electrolyte solvent, at 80 ° C. for 72 hours. Immediately after taking out from the preparation liquid, the adhesive force (N / 25 mm) was measured in the same manner as above. This measured value was used as the adhesive strength after immersion in the electrolyte solvent. The results are shown in Table 1.

  In the above test, the battery pressure-sensitive adhesive sheets of Examples did not cause cohesive failure of the pressure-sensitive adhesive layer, but the battery pressure-sensitive adhesive sheets of Comparative Example did cause cohesive failure of the pressure-sensitive adhesive layer.

[Test Example 4] (Evaluation of electrolytic solution resistance)
The release sheet was peeled from the battery pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to an aluminum plate (thickness: 1 mm), which was used as a test piece. Preparation of the obtained test piece by dissolving lithium hexafluorophosphate (LiPF ₆ ) at a concentration of 1 mol / L in a mixed solution of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 as an electrolytic solution The solution was sealed in an aluminum laminate bag and heated in an environment of 80 ° C. for 3 days. Then, the adhesive sheet for a battery was peeled off from the aluminum plate with tweezers. Check the state of the battery adhesive sheet immersed in the electrolytic solution, the strength of the adhesive force when peeling the battery adhesive sheet, and the state when peeling the battery adhesive sheet, and check the electrolytic resistance based on the following criteria. The liquid property was evaluated. Pass 3 or more. The results are shown in Table 1.
5: Peeled off at the interface between the pressure sensitive adhesive and the adherend (high adhesion).
4 ... Peeled off at the interface of the pressure sensitive adhesive / adherend (in the adhesive force).
3: Peeled off at the adhesive / adherent interface (low adhesive strength).
2 ... The adhesive swelled and cohesively destroyed.
1 ... Peeled off while immersed in the electrolytic solution.

  As is clear from Table 1, in the pressure-sensitive adhesive sheets for batteries of Examples, cohesive failure did not occur in the pressure-sensitive adhesive layer even when immersed in an electrolytic solution solvent and an electrolytic solution, and high adhesive strength (adhesion before immersion in electrolytic solution solvent was observed. 70% or more). Further, it was found that the pressure-sensitive adhesives of the battery pressure-sensitive adhesive sheets of the examples showed a high gel fraction even after being immersed in the electrolytic solution solvent, and were difficult to be eluted in the electrolytic solution solvent.

  The pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet for a battery according to the present invention are suitable for attaching an electrode take-out tab to an electrode (current collector) inside a lithium ion battery.

DESCRIPTION OF SYMBOLS 1 ... Battery adhesive sheet 11 ... Base material 12 ... Hard coat layer 13 ... Adhesive layer 14 ... Release sheet 2 ... Lithium ion battery 21 ... Exterior body 22 ... Positive electrode terminal 23 ... Negative electrode terminal 24 ... Electrode body 241 ... Positive electrode current collector Body 241a ... Positive electrode active material layer 242 ... Negative electrode current collector 242a ... Negative electrode active material layer 243 ... Separator 244 ... Electrode take-out tab

Claims (4)

A pressure-sensitive adhesive sheet for a battery, comprising a base material and a pressure-sensitive adhesive layer laminated on one surface side of the base material,
The substrate is a film made of a polymer having a nitrogen-containing ring structure in the main chain,
The adhesive layer,
As a monomer unit constituting the polymer, the alkyl group has 6 or more and 20 or less (meth) acrylic acid alkyl ester, and a monomer having a carboxy group in the molecule, and has a weight average molecular weight of 50,000 or more. A (meth) acrylic acid ester polymer having a viscosity of 2.5 million or less,
It is formed from an adhesive composition containing a metal chelate crosslinking agent,
The glass transition temperature of the (meth) acrylic acid ester polymer (A) is −70 ° C. or higher and lower than 0 ° C.,
The battery having a gel fraction of 80% or more and 100% or less after the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is immersed in a solvent of a non-aqueous electrolyte solution at 80 ° C. for 72 hours. Adhesive sheet.   The pressure-sensitive adhesive sheet for a battery according to claim 1, wherein the (meth) acrylic acid ester polymer contains a monomer having an alicyclic structure in the molecule as a monomer unit constituting the polymer.   The pressure-sensitive adhesive sheet for a battery according to claim 1, wherein a hard coat layer is formed on a surface of the base material on the pressure-sensitive adhesive layer side. Lithium ion characterized by being fixed in a state in which two or more conductors are in contact with each other by using the battery pressure-sensitive adhesive sheet according to any one of claims 1 to 3 inside the battery. battery.

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