JP2018181853A - Sticky sheet for battery, and lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a sticky composition involving a sticker hard to elute into an electrolyte solution, which allows a satisfactory adhesive force to be exerted to an adherend even if a sticky sheet is put in contact with an electrolyte solution; a sticky sheet for a battery; and a lithium ion battery.SOLUTION: A sticky sheet 1 for a battery comprises: a base material 11; and a sticker layer 13. In the sticky sheet 1 for a battery, the base material 11 is a film comprising a polymer having, in its main chain, a nitrogen-containing ring structure. The sticker layer 13 is formed from a sticky composition including (meth)acrylic ester polymer which includes, as a monomer unit for constituting the polymer, (meth)acrylic acid alkyl ester of which the number of carbon atoms of an alkyl group is 6 or more and 20 or less, and a monomer having a carboxy group in its molecule, and has a weight-average molecular weight of 50000 or more and 2500000 or less. After a sticker included in the sticker layer 13 is immersed in a solvent of a nonaqueous electrolyte solution at 80°C for 72 hrs, the gel fraction of the sticker is 80% or more and 100% or less.SELECTED DRAWING: Figure 1

Description

  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 produced using them.

  In some batteries, a strip-shaped laminate in which a positive electrode, a negative electrode, and a separator positioned between them are stacked is accommodated inside in a wound state. The positive electrode and the negative electrode are respectively connected to electrode extraction tabs made of a conductor, and the positive electrode and the negative electrode are electrically connected to the positive electrode terminal and the negative electrode terminal of the battery through these electrode extraction tabs, respectively. .

  A pressure-sensitive adhesive tape is used to fasten the laminate and fix the electrode extraction tab to the electrode. Patent Document 1 discloses such an adhesive tape. The pressure-sensitive adhesive tape comprises a substrate and a pressure-sensitive adhesive layer provided on one surface of the substrate, and the pressure-sensitive adhesive layer is mainly composed of rubber, particularly butyl rubber.

JP, 2011-138632, A

  The pressure-sensitive adhesive tape used inside the battery may come in contact with the electrolytic solution filled inside the battery or may be exposed to heat generated during charge and discharge. Particularly in recent years, development of small-sized and high-performance batteries has been promoted, and adhesive tapes used inside the batteries are exposed to more severe conditions.

  In order to exhibit the performance as a battery well, the adhesive tape maintains high adhesion with the adherend even when exposed to the above-mentioned severe conditions, and the adhesive It is required that they do not adversely affect the battery performance without eluting into the electrolyte. However, conventional adhesive tapes have sometimes failed to satisfy such requirements.

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

  In order to achieve the above object, firstly, the present invention is a pressure-sensitive adhesive sheet for a battery comprising a substrate and a pressure-sensitive adhesive layer laminated on one side of the substrate, wherein the substrate is It is a film consisting of a polymer having a nitrogen-containing ring structure in its main chain, and the pressure-sensitive adhesive layer is a (meth) acrylic having 6 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. An adhesive composition formed from 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 The gel fraction of the pressure-sensitive adhesive after immersing the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer in the solvent of the non-aqueous electrolytic solution for 72 hours at 80.degree. C. is 80% to 100%. Battery adhesive Providing the door (invention 1). In the present specification, a sheet also includes the concept of a tape.

  In the above invention (Invention 1), the (meth) acrylic acid ester polymer is a monomer unit constituting the polymer, in particular, the (meth) acrylic acid having an alkyl group having 6 to 20 carbon atoms By containing the alkyl ester, it exhibits good tackiness and, at the same time, is excellent in electrolytic solution resistance due to its hydrophobicity. Therefore, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for a battery is formed of the pressure-sensitive adhesive composition according to the above-mentioned invention (invention 1), the pressure-sensitive adhesive layer swells even when the pressure-sensitive adhesive sheet for battery is in contact with an electrolytic solution. Cohesive failure is suppressed by this, and excellent adhesion to an adherend is exhibited, and the adhesive is difficult to elute into 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 | numerator as a monomer unit which comprises the said polymer (invention 2).

  The adhesive composition according to the above invention (inventions 1 and 2) preferably contains a metal chelate crosslinking agent (invention 3).

  In the said invention (invention 1-3), it is preferable that the hard-coat layer is formed in the surface at the side of the said adhesive layer in the said base material (invention 4). In addition, the hard-coat layer in this specification means the layer which consists of material harder than a base material, and does not mean the layer which exists in the outermost layer of a film.

  Secondly, in the present invention, lithium is characterized in that two or more conductors are in contact with each other by using the above-mentioned pressure-sensitive adhesive sheet for batteries (inventions 1 to 4) inside the battery. An ion battery is provided (invention 5).

  According to the 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 is in contact with the electrolytic solution, the adhesive layer is inhibited from being cohesively broken due to swelling The pressure-sensitive adhesive sheet for batteries exhibits excellent adhesion to an adherend, and the pressure-sensitive adhesive is less likely to be eluted 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 section disassembled perspective view of a lithium ion battery concerning one embodiment of the present invention. It is an expanded perspective view of an electrode body of a lithium ion battery concerning one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
The adhesive composition which concerns on one Embodiment of this invention is an adhesive composition for forming the adhesive layer of the adhesive sheet for batteries. The “pressure-sensitive adhesive sheet for battery” in the present specification is a pressure-sensitive adhesive sheet used at a portion which may come in contact with an electrolytic solution in the production of a battery, preferably a pressure-sensitive adhesive sheet used inside a battery, It may be a pressure-sensitive adhesive sheet for battery interior. The battery is preferably a non-aqueous battery. Therefore, it is preferable that the electrolyte used for the said battery is a non-aqueous electrolyte. The battery pressure-sensitive adhesive sheet in the present specification is preferably a pressure-sensitive adhesive sheet attached to a portion which may be immersed in an electrolytic solution inside a non-aqueous battery or a portion which may be in contact with the electrolytic solution. A lithium ion battery is particularly preferable as the non-aqueous battery.

  The adhesive composition according to the present embodiment (hereinafter sometimes referred to as “adhesive composition P”) has, as a monomer unit constituting a polymer, an alkyl group having 6 to 20 carbon atoms (Meth) acrylic acid alkyl ester, and (meth) acrylic acid ester polymer (A) containing a carboxyl group-containing monomer (carboxy group-containing monomer) in the molecule, preferably further including a metal chelate crosslinking agent (B) And particularly preferably further comprises a silane coupling agent (C). In the present specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. Other similar terms are also the same. 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 6 to 20 carbon atoms in the alkyl group, and a carboxy group in the molecule It contains 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 adhesive and exhibits hydrophobicity due to the large carbon number of the alkyl group. This hydrophobic property has the property that the affinity to the electrolyte (including non-aqueous electrolyte) is low. Therefore, the obtained pressure-sensitive adhesive exhibits good adhesion and also has excellent electrolyte resistance due to the above-mentioned hydrophobicity. Therefore, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for a battery is formed of the pressure-sensitive adhesive composition P containing a (meth) acrylic acid ester polymer (A), the pressure-sensitive adhesive sheet for the battery comes into contact with the electrolytic solution (immersed Even if the case is included, the adhesive layer is suppressed from being cohesively broken by swelling, and the battery pressure-sensitive adhesive sheet exerts excellent adhesion to the adherend. In addition, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer hardly dissolves in the electrolytic solution, and the pressure-sensitive adhesive does not adversely affect the battery performance. By these, the malfunction, thermal runaway and short circuit of the battery resulting from the adhesive sheet for batteries are suppressed.

  The said alkyl group of C6-C20 (meth) acrylic-acid alkylester of an alkyl group may be linear, and may be branched. The carbon number of the alkyl group needs to be 6 or more, preferably 7 or more, and particularly preferably 8 or more from the viewpoint of hydrophobicity. On the other hand, the carbon number of the alkyl group needs to be 20 or less, preferably 18 or less, particularly preferably 15 or less, and more preferably 10 or less from the viewpoint of adhesiveness. Is preferred.

  Examples of the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group include n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth ) 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 (meth) acrylic acid alkyl esters, from the viewpoint of adhesiveness and hydrophobicity, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl acrylate and the like In particular, 2-ethylhexyl acrylate and isooctyl acrylate are 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 (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer The content is preferably 60% by mass or more, particularly 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 adhesion and electrolytic solution resistance. In addition, the (meth) acrylic acid ester polymer (A) contains, as a monomer unit constituting the polymer, 99 mass% or less of (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms of an alkyl group. Is preferably contained, more preferably 97% by mass or less, particularly preferably 90% by mass or less, and still more preferably 85% by mass or less. By adjusting the (meth) acrylic acid alkyl ester to 99% by mass or less, other monomer components can be introduced into the (meth) acrylic acid ester polymer (A) in a suitable amount.

  On the other hand, a carboxy group-containing monomer which the (meth) acrylic acid ester polymer (A) contains as a monomer unit constituting the polymer has an effect of improving the adhesive strength of the obtained adhesive. Moreover, when the adhesive composition P contains the metal chelate type crosslinking agent (B) mentioned later, the carboxy group derived from the said carboxy-group containing monomer is a metal chelate at the time of bridge | crosslinking of a (meth) acrylic acid ester polymer (A). It reacts with the crosslinking agent (B) to form a crosslinked structure which is a three-dimensional network structure. The pressure-sensitive adhesive having a crosslinked structure by the reaction of 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 hardly eluted even when in contact with the electrolytic solution. Therefore, combined with the electrolytic solution resistance by the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group, the obtained adhesive becomes difficult to elute by the electrolytic solution.

  Examples of carboxy group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid and the like. Among these, acrylic acid is preferred. According to acrylic acid, the above effects become 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, as a lower limit value, 0.5% by mass or more of a carboxy group-containing monomer as a monomer unit constituting the polymer, particularly 1% by mass or more Preferably, the content is 3% by mass or more. In addition, the (meth) acrylic acid ester polymer (A) preferably contains, as an upper limit value, 30% by mass or less of a carboxy group-containing monomer as a monomer unit constituting the polymer, particularly 20% by mass or less Preferably, the content is 10% by mass or less. When the (meth) acrylic acid ester polymer (A) contains a carboxy group-containing monomer in the above amount as a monomer unit, the above-mentioned effects become more excellent in the obtained adhesive.

  Moreover, it is preferable that the (meth) acrylic acid ester polymer (A) contains the monomer (alicyclic structure containing monomer) which has an alicyclic structure in a molecule | numerator as a monomer unit which comprises the said polymer. This alicyclic structure-containing monomer exhibits hydrophobicity by being bulky. Therefore, the obtained pressure-sensitive adhesive combines with the hydrophobicity of the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms in the alkyl group, and the obtained pressure-sensitive adhesive becomes more excellent in electrolytic solution resistance. Therefore, even when the pressure-sensitive adhesive sheet for a battery comes into contact with the electrolyte, the 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 than the adherend Exerts an adhesive power. In addition, the pressure-sensitive adhesive constituting 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 be a saturated structure or may have an unsaturated bond in part. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic or tricyclic ring. It is preferable that the said alicyclic structure is a polycyclic alicyclic structure (polycyclic structure) from a viewpoint of said hydrophobic property and the electrolyte solution resistance by it. Furthermore, in view of the compatibility between the (meth) acrylic acid ester polymer (A) and the other components, it is particularly preferable that the polycyclic structure be a bi- to tetra-cyclic structure. In addition, from the viewpoint of effectively exhibiting electrolytic solution resistance, the carbon number of the alicyclic structure (the total carbon number of the portion forming a ring, when a plurality of rings are independently present) The total number of carbon atoms is preferably 5 or more, and particularly preferably 7 or more. On the other hand, the upper limit of the carbon number of the alicyclic structure is not particularly limited, but it is preferably 15 or less and particularly preferably 10 or less from the viewpoint of compatibility as described above.

  As an alicyclic structure, for example, cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.) And cycloalkene skeletons (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, cubane skeleton, basquetan skeleton, housen skeleton, spiro skeleton, etc., and among them, it exhibits superior durability. Those containing a dicyclopentadiene skeleton (the carbon number of the alicyclic structure: 10), an adamantane skeleton (the carbon number of the alicyclic structure: 10) or an isobornyl skeleton (the carbon number of the alicyclic structure: 7) are preferred. Contains an isobornyl skeleton Preference is.

  As the above-mentioned alicyclic structure-containing monomer, a (meth) acrylic acid ester monomer containing the above-mentioned skeleton is preferable, and specifically, (meth) acrylic acid cyclohexyl, (meth) acrylic acid dicyclopentanyl, (meth) acrylic acid Examples include adamantyl acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyl oxyethyl (meth) acrylate and the like, among which (meth) acrylic exerting more excellent durability Dicyclopentanyl acid, adamantyl (meth) acrylate or isobornyl (meth) acrylate are preferred, and isobornyl (meth) acrylate is particularly preferred. One of these may be used alone, or two or more of these may be used in combination.

  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 enhancing the content, the alicyclic structure-containing monomer is preferably contained in an amount of 5% by mass or more, particularly preferably 7.5% by mass or more, and further preferably 10% by mass or more. Moreover, the (meth) acrylic acid ester polymer (A) is a viewpoint which prevents that the quantity of C6-C20 (meth) acrylic-acid alkylester of an alkyl group runs short, and electrolyte resistance falls. Therefore, it is preferable to contain 35 mass% or less of an alicyclic structure containing monomer as a monomer unit which comprises the said polymer, it is preferable to contain especially 30 mass% or less, and also to contain 20 mass% or less preferable. When the content of the alicyclic structure-containing monomer is in the above range, the above-mentioned electrolytic solution resistance becomes more excellent.

  The (meth) acrylic acid ester polymer (A) may optionally contain other monomers as monomer units constituting the polymer. The other monomer may be a monomer containing a functional group having reactivity (except for a carboxy group), or may be a monomer not containing a functional group having reactivity.

  Examples of the monomer containing a functional group having reactivity include a monomer having a hydroxyl group in the molecule (hydroxyl group containing monomer), a monomer having an amino group in the molecule (amino group containing monomer), and the like.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (iii) 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 having a functional group having reactivity is only the above-mentioned carboxy group-containing monomer. Is preferred.

  On the other hand, as a monomer not containing a reactive functional group, for example, carbon of an alkyl group such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate and butyl (meth) acrylate (Meth) acrylic acid alkyl ester having a number of 1 to 4 (meth) acrylic acid alkyl ester, (meth) acrylic acid methoxyethyl, (meth) acrylic acid alkoxyalkyl ester such as ethoxyethyl (meth) acrylic acid, (meth) acrylic acid N, N- Non-crosslinkable tertiary amino group-containing (meth) acrylic esters such as dimethylaminoethyl, N, N-dimethylaminopropyl (meth) acrylate, (meth) acryloyl morpholine, (meth) acrylic esters, (meth) acrylamides, dimethylacrylamides, acetic acid Vinyl, styrene and the like can be mentioned. 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 value of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not less than the above, the elution resistance of the obtained pressure-sensitive adhesive to the electrolytic solution is more excellent.

  Further, the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably not more than 2,500,000 as an upper limit value, more preferably not more than 2,000,000, and particularly preferably not more than 1,500,000. Furthermore, it is preferable that it is 1.2 million or less. When the upper limit value of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above, the adhesive strength 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 less than 20 ° C., particularly preferably less than 0 ° C., and further preferably less than −40 ° C. Is preferred. When the upper limit value of the glass transition temperature of the (meth) acrylate polymer (A) is above, the tackiness of the pressure-sensitive adhesive at normal temperature is high, and it becomes difficult to peel off when immersed in an electrolytic solution. On the other hand, the lower limit value of the glass transition temperature (Tg) of the (meth) acrylic acid ester polymer (A) is not particularly limited, but from the viewpoint of improving the durability in the electrolytic solution, usually lower than -70 ° C. In particular, the temperature is preferably -62.5 ° C or higher, and more preferably -55 ° C or higher. 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 FOX equation.

  In addition, in the adhesive composition P, a (meth) acrylic acid ester polymer (A) may be used individually by 1 type, and may be used in combination of 2 or more type.

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

  As a metal chelate type crosslinking agent (B), the metal chelate compound whose metal atom is aluminum, a zirconium, titanium, zinc, iron, tin etc. can be used. Among them, aluminum chelate compounds are particularly preferable. The aluminum chelate compound particularly effectively exerts the above-mentioned elution resistance to the electrolytic solution.

  As an aluminum chelate compound, for example, diisopropoxyaluminum monooleyl acetoacetate, monoisopropoxyaluminum bisoleyl acetoacetate, monoisopropoxyaluminum monooleate monoethyl acetoacetate, diisopropoxyaluminum monolauryl acetoacetate, diisopropoxyaluminum Aluminum monostearylacetoacetate, diisopropoxyaluminum monoisostearylacetoacetate, monoisopropoxyaluminum mono-N-lauroyl-β-alanate monolaurylacetoacetate, 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 effect. These may be used alone or in combination of two or more.

  Moreover, as other metal chelate compounds, for example, titanium tetrapropionate, titanium tetra-n-butylate, titanium tetra-2-ethylhexanoate, zirconium sec-butylate, zirconium diethoxy-tert-butyrate, triethanol Amine titanium dipropionate, ammonium salt of titanium lactate, tetraoctylene glycol titanate and the like can be mentioned. These may be used alone or in combination of two or more.

  One of the above-mentioned metal chelate-based crosslinking agents (B) may be used alone, or two or more thereof may be used in combination.

  Content of the metal chelate type crosslinking agent (B) in adhesive composition P which concerns on this embodiment is 0.1 mass as a lower limit with respect to 100 mass parts of (meth) acrylic acid ester polymers (A). The content is preferably at least parts, more preferably at least 0.3 parts by mass, particularly preferably at least 0.5 parts by mass, and still more preferably at least 1.2 parts by mass. In addition, the content of the metal chelate crosslinking agent (B) is preferably 5 parts by mass or less as the upper limit value, particularly preferably 4 parts by mass or less, and further preferably 3 parts by mass or less . When the content of the metal chelate crosslinking agent (B) is in the above range, the above-described effects become more excellent.

(1-3) Silane coupling agent (C)
The adhesive composition P preferably further contains a silane coupling agent (C). When the adhesive composition P contains the silane coupling agent (C), the adherend (especially metal member) even when the battery pressure-sensitive adhesive sheet is in contact with the electrolyte (including the case of immersion). Demonstrates excellent tackiness). As a result, the overlapping action of the adhesion and resistance to electrolyte by the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms of the alkyl group constituting the (meth) acrylic acid ester polymer (A) is exerted Thus, the adhesive strength is further improved, and peeling of the battery pressure-sensitive adhesive sheet from the adherend is effectively suppressed. As a result, the fall of the battery performance resulting from the said adhesive sheet for batteries is suppressed. Further, even in the case where the hard coat layer is formed on the surface of the substrate on the side of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet for batteries, the pressure-sensitive adhesive layer has high adhesion to the hard coat layer. Therefore, it is possible to prevent the occurrence of peeling or the like at the interface between the hard coat layer and the adhesive layer by immersing the adhesive sheet for battery in the electrolytic solution, and to make the adhesive strength after immersion in the electrolytic solution solvent higher. . Moreover, when peeling a release sheet from an adhesive layer, it can also suppress that an adhesive layer adheres to a release sheet and peels from a 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).

  As such a silane coupling agent (C), for example, polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, mercapto groups such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane Amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, etc. Silicon compounds, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, or at least one of these, and alkyltril groups such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, etc. A condensate with a silicon compound etc. are mentioned. Among these, in view of the above effects, silicon compounds having an epoxy structure are preferable, and 3-glycidoxypropyltrimethoxysilane is particularly preferable. One of these may be used alone, or two or more of these may be used in combination.

  The content of the silane coupling agent (C) in the adhesive composition P is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A), and 0 The content is more preferably 0.05 parts by mass or more, particularly preferably 0.1 parts by mass or more, and further preferably 0.4 parts by mass or more. In addition, 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 adhesion after immersion in a solvent of an electrolytic solution is more excellent.

(1-4) Various Additives In the adhesive composition P, various additives generally used for acrylic pressure-sensitive adhesives, for example, tackifiers, antioxidants, softeners, fillers, etc., are optionally added. can do. In addition, the below-mentioned polymerization solvent and dilution solvent shall not be contained in the additive which comprises the adhesive composition P.

(2) Production of adhesive composition The adhesive composition P produces a (meth) acrylic acid ester polymer (A), and the obtained (meth) acrylic acid ester polymer (A) optionally produces It can manufacture by adding a metal chelate type crosslinking agent (B), a silane coupling agent (C), an additive, etc.

  The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) can be carried out by solution polymerization or the like, using a polymerization initiator, if desired. As a polymerization solvent, ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone etc. are mentioned, for example, You may use 2 or more types together.

  As a polymerization initiator, an azo compound, an organic peroxide, etc. are mentioned, You may use 2 or more types together. As an azo compound, for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis (2-methyl propionate) 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,2'-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  As the organic peroxide, for example, benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, di (2-ethoxyethyl) peroxy Dicarbonate, t-butyl peroxy neodecanoate, t-butyl peroxy bivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like can be mentioned.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercapto ethanol.

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

  In addition, in order to adjust the adhesive composition P to a viscosity suitable for coating or to adjust the pressure-sensitive adhesive layer to a desired film thickness, appropriately add it to the above-mentioned polymerization solvent and dilute it with a dilution solvent, etc. It may be a coating solution described later. Examples of the dilution 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.

[Adhesive sheet for battery]
The adhesive sheet for batteries which concerns on one Embodiment of this invention is equipped with a base material and the adhesive layer laminated | stacked on one surface side of a base material, The said adhesive layer starts the adhesive composition P mentioned above. It is formed. Hereinafter, the adhesive sheet for batteries which concerns on preferable embodiment is demonstrated.

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

  (Meth) acrylic acid ester polymer for battery pressure-sensitive adhesive sheet 1 having pressure-sensitive adhesive layer 13 formed from pressure-sensitive adhesive composition P described above, even when it comes in contact with an electrolytic solution (including the case of immersion) Cohesive failure of the pressure-sensitive adhesive layer 13 due to swelling is suppressed by the good adhesiveness and electrolytic solution resistance of the (meth) acrylic acid alkyl ester having 6 to 20 carbon atoms of the alkyl group constituting (A) The battery pressure-sensitive adhesive sheet 1 exerts excellent adhesion to an adherend. In addition, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 13 does not easily elute into the electrolytic solution, and the pressure-sensitive adhesive does not adversely affect the battery performance. By these, the malfunction, thermal runaway and short circuit of the battery resulting from the adhesive sheet 1 for batteries are suppressed.

  Further, the battery pressure-sensitive adhesive sheet 1 according to the present embodiment can secure insulation even when the substrate 11 or the pressure-sensitive adhesive layer 13 is carbonized by providing the hard coat layer 12, and the battery Safety can be improved.

1. Base Material In the pressure-sensitive adhesive sheet 1 for a battery according to the present embodiment, the base material 11 preferably has a flame retardancy satisfying the flame retardancy level V-0 of the UL94 standard. Since the base material 11 has such a flame retardance, even when heat is generated by the use of a normal battery, modification and deformation of the base material 11 are suppressed. In addition, even if the battery has a defect and generates heat excessively, ignition and combustion of the base material 11 are suppressed, and a serious accident is prevented.

  The material of the substrate 11 can be appropriately selected from the viewpoint of flame retardancy, heat resistance, insulation, reactivity with the electrolyte, permeability of the electrolyte, and the like. In particular, as the substrate 11, it is preferable to use a resin film. Examples of the resin film include polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyolefin films such as polyethylene film and 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, fluorine resin film, polyamide Resins such as film, polyimide film, polyamide imide film, acrylic resin film, polyurethane resin film, norbornene polymer film, cyclic olefin polymer film, cyclic conjugated diene polymer film, vinyl alicyclic hydrocarbon polymer film Films or laminated films thereof are mentioned. In particular, from the viewpoint of exhibiting excellent flame retardancy and heat resistance, a film of a polymer containing nitrogen in the main chain (which may contain a component other than the polymer, as in the present specification) is preferred. In particular, a film of a polymer having a nitrogen-containing ring structure in the main chain is preferred, and a film of a polymer having a nitrogen-containing ring structure and an aromatic ring structure in the main chain is more preferred. 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, more preferably 10 to 100 μm, and still more preferably 15 to 40 μm. When the thickness of the substrate 11 is 5 μm or more, the substrate 11 is given appropriate rigidity, and curling occurs even when curing shrinkage occurs when the hard coat layer 12 is formed on the substrate 11 The occurrence is effectively suppressed. In addition, when the thickness of the substrate 11 is 200 μm or less, the battery pressure-sensitive adhesive sheet 1 has appropriate flexibility, and on the surface where a step is present as in the case of fixing the electrode and the electrode extraction tab. Even when the battery pressure-sensitive adhesive sheet 1 is attached, the step can be favorably followed.

2. Hard Coat Layer (1) Physical Properties of Hard Coat Layer In the battery pressure-sensitive adhesive sheet 1 according to this embodiment, the hard coat layer 12 in the state provided on the substrate 11 is 250 g / cm using # 0000 steel wool. It is preferable that the hard coat layer 12 is rubbed back and forth 10 cm for 10 cycles with a load of ^{2 and} no scratch is generated. With such steel wool resistance evaluation, the permeation of the hard coat layer 12 of the electrolytic solution is effectively blocked, and the detachment 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 of 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 can be cured by irradiation with active energy rays to exhibit a desired hardness.

  Specific examples of the active energy ray-curable component include polyfunctional (meth) acrylate monomers, (meth) acrylate prepolymers, active energy ray curable polymers, etc. Among them, polyfunctional (meth) acrylates are particularly preferred. It is preferable that it is a system monomer and / or a (meth) acrylate type prepolymer. The polyfunctional (meth) acrylate monomer and the (meth) acrylate prepolymer may be used alone or in combination. In the present specification, (meth) acrylate means both acrylate and methacrylate. Other similar terms are also the same.

  As a polyfunctional (meth) acrylate monomer, for example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (Meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified phosphate di (meth) acrylate, allylated Cyclohexyl di (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 Polyfunctional (meth) acrylates such as hexa (meth) acrylate and caprolactone modified dipentaerythritol hexa (meth) acrylate are mentioned. One of these may be used alone, or two or more of these may be used in combination. The polyfunctional (meth) acrylate monomer is not particularly limited, but is more preferably less than 1,000 in molecular weight from the viewpoint of preventing the inorganic filler from coming out of the hard coat layer 12 while immersed in the electrolytic solution.

  On the other hand, as a (meth) acrylate type prepolymer, prepolymers, such as polyester acrylate type, epoxy acrylate type, urethane acrylate type, a polyol acrylate type, are mentioned, for example. The prepolymers may be used alone or in combination of two or more.

  It is preferable that the glass transition point after hardening of the active energy ray curable component which comprises the hard-coat layer 12 of this embodiment is 130 degreeC or more, It is more preferable that it is 150 degreeC or more, A glass transition point is observed It is particularly preferred that the 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 provided with such a hard coat layer 12 is included. Battery performance and safety will also be excellent.

  In addition, when using 2 or more types of active energy ray curable components in the hard-coat layer 12 of this embodiment, it is preferable that those active energy ray curable components are mutually excellent in compatibility.

(2-2) Inorganic Filler It is preferable that the composition for hard-coat layers which comprises the hard-coat layer 12 of this embodiment contains an inorganic filler. By containing an inorganic filler, rigidity is imparted to the hard coat layer 12 of the present embodiment, and damage such as breakage of the battery pressure-sensitive adhesive sheet 1 or formation of a hole due to an impact 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 etc., beads obtained by spheroidizing them, single crystal fibers, glass fibers, etc. These may be used alone or in combination 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. In addition, these inorganic fillers can also be used in the form which disperse | distributed in the dispersion medium and became sol state.

  The inorganic filler is also preferably surface-modified. As such an inorganic filler, reactive silica can be exemplified.

  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 fine silica particles (reactive silica) surface-modified with an organic compound having an active energy ray-curable unsaturated group usually have, for example, silanol groups on the surface of fine silica particles having an average particle diameter of 1 to 200 nm and the corresponding silanol groups. It can be obtained by reacting an active energy ray-curable unsaturated group-containing organic compound having a reactive functional group (for example, an isocyanate group, an epoxy group, a carboxy group, etc.). In addition, as said active energy ray curable unsaturated group, a (meth) acryloyl group and a vinyl group can be mentioned preferably.

  As an organic-inorganic hybrid material (organosilica sol) containing such reactive silica and the above-mentioned polyfunctional (meth) acrylate monomer and / or (meth) acrylate prepolymer, for example, trade name “OPSTAR Z7530” “Opster Z 7524”, “Opster TU 4086”, “Opster Z 7537” (all 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 with bare silanol groups on the silica surface are suspended in a colloidal state in a dispersion medium, and silanol coupling of the silica surface is silane coupling. And organo silica sol surface-treated with an agent and the like.

  The average particle diameter of the inorganic filler used in the present embodiment is preferably 1 to 1000 nm, particularly preferably 10 to 500 nm, and still more preferably 15 to 200 nm. When the average particle diameter of the inorganic filler is 1 nm or more, the hard coat layer 12 obtained by curing the hard coat layer composition has higher rigidity. In addition, when the average particle diameter of the inorganic filler is 1000 nm or less, the dispersibility of the inorganic filler in the composition for the 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 asperities on the surface of the hard coat layer 12 opposite to the substrate 11. Furthermore, by forming the pressure-sensitive adhesive layer 13 on the surface, it is possible to obtain very high smoothness on the surface of the pressure-sensitive adhesive layer 13 opposite to the hard coat layer 12. Thus, the pressure-sensitive adhesive layer 13 can exhibit excellent adhesion to the adherend. In addition, the average particle diameter of an inorganic filler shall be measured by the laser diffraction scattering type particle size distribution measuring apparatus.

  It is preferable that content of the inorganic filler in the hard-coat layer 12 of this embodiment is 0-90 mass% (90 mass% or less) with respect to the hard-coat layer 12, and it is more preferable that it is 30-85 mass%. The content is preferably 40 to 80% by mass, and more preferably 45 to 70% by mass. When the inorganic filler is contained, when the content 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, 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 this embodiment may contain various additives other than the component mentioned above. As various additives, for example, a photopolymerization initiator, an antioxidant, an antistatic agent, a silane coupling agent, an antiaging agent, a thermal polymerization inhibitor, a colorant, a surfactant, a storage stabilizer, a plasticizer, and a lubricant , Antifoam agents, organic fillers and the like.

  In the case of forming the hard coat layer 12 using ultraviolet light as active energy rays, 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, acyl phosphine oxide compounds, benzoin compounds, acetophenone compounds, titanocene compounds, thioxanthone Compounds, peroxide compounds and the like can be mentioned. Specifically, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, benzoin, benzoin Examples include methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloro anthraquinone and the like. One of these may be used alone, or two or more of these may be used in combination.

  In general, the content of the photopolymerization initiator in the composition for a hard coat layer is preferably 0.1 to 20 parts by mass, 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, when 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 on which a step is present as in the case of fixing the electrode and the electrode extraction tab Even in the case where the battery pressure-sensitive adhesive sheet 1 is attached, the battery pressure-sensitive adhesive sheet 1 can satisfactorily follow the step.

3. Pressure-Sensitive Adhesive Layer The pressure-sensitive adhesive layer 13 is formed of the above-described pressure-sensitive adhesive composition P. The formation method of the adhesive layer 13 is mentioned later.

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

  On the other hand, the upper limit value 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 level difference 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 favorably followed.

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

(2) Thickness of Pressure-Sensitive Adhesive Layer The thickness (value measured according to JIS K7130) of the pressure-sensitive adhesive layer 13 is preferably 1 to 50 μm, particularly preferably 3 to 15 μm, and further preferably 4 It is preferable that it is -9 micrometers. By the thickness of the adhesive layer 13 being 1 micrometer or more, the adhesive sheet 1 for batteries can exhibit the more outstanding adhesive force. Moreover, when the thickness of the adhesive layer 13 is 50 micrometers or less, the quantity of the electrolyte solution which infiltrates from the edge part of the adhesive layer 13 can be reduced effectively.

4. Release Sheet The release sheet 14 protects the pressure-sensitive adhesive layer until the use of the battery pressure-sensitive adhesive sheet 1 and is peeled off when the battery pressure-sensitive adhesive sheet 1 is used. In the adhesive sheet 1 for batteries which concerns on this embodiment, the peeling sheet 14 is not necessarily required.

  As the release sheet 14, for example, 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, fluorine resin film And liquid crystal polymer films are used. Moreover, these crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  Peeling treatment is preferably performed on the peeling surface of the peeling sheet 14 (the surface in contact with the pressure-sensitive adhesive layer 13). Examples of the release agent used for 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 Adhesive Sheet for Battery, Etc. The adhesive strength (adhesive strength before immersion in electrolytic solution solvent) to the aluminum plate of the adhesive sheet 1 for battery according to the present embodiment is preferably 0.5 N / 25 mm or more as a lower limit, More preferably, it is 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 value of the adhesive force before the electrolyte solution solvent immersion of the adhesive sheet 1 for batteries is above, the adhesive sheet 1 for batteries is an adherend (especially metal) before the adhesive sheet 1 for battery contacts the electrolyte. It is difficult for the problem of peeling off from the member) to occur. The upper limit of the adhesive strength before immersion in the electrolytic solution solvent is not particularly limited, but usually 50 N / 25 mm or less is preferable, 40 N / 25 mm or less is more preferable, and particularly 30 N / 25 mm or less Preferably, it is more preferably 10 N / 25 mm or less. The adhesive strength in the present specification basically means the adhesive strength measured by the 180 ° peeling method according to JIS Z 0237: 2009, and the detailed measuring method is as shown in the test example described later.

  Moreover, the adhesive force for the aluminum plate of the said battery adhesive sheet 1 after sticking the battery adhesive sheet 1 which concerns on this embodiment on an aluminum plate and being immersed in the solvent of non-aqueous electrolyte solution for 72 hours at 80 degreeC The lower limit of the adhesive strength after immersion in a 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 Furthermore, it is preferable that it is 2.0 N / 25 mm or more. Since the lower limit value of the adhesive force after the electrolytic solution solvent immersion of the adhesive sheet 1 for batteries is above, even after the adhesive sheet 1 for batteries contacts (immerses) the electrolytic solution, the adhesive sheet 1 for batteries is It is difficult for the problem of peeling off from the adherend (especially metal member) to occur. The upper limit of the adhesive strength after immersion in the electrolytic solution solvent is not particularly limited, but usually 40 N / 25 mm or less is preferable, 30 N / 25 mm or less is more preferable, and particularly 20 N / 25 mm or less Preferably, it is more preferably 10 N / 25 mm or less. The pressure-sensitive adhesive sheet 1 for a battery according to the present embodiment comprises the (meth) acrylic acid ester polymer (A) described above, preferably a metal chelate crosslinking agent (B), particularly preferably a silane coupling agent (C). By having the adhesive layer 13 formed using the adhesive composition P to contain, the outstanding adhesive force of the said range can be achieved. Here, the solvent of the non-aqueous electrolyte solution is a preparation solution in which ethylene carbonate and diethyl carbonate are mixed at a volume ratio of 1: 1.

  The adhesion after immersion in the electrolyte solvent is preferably 50% or more, more preferably 60% or more, and particularly preferably 70% or more, with respect to the adhesion before immersion in the electrolyte solvent. And further 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 in the above range, the battery pressure-sensitive adhesive sheet 1 is more suitable in which the adhesive strength and the heat resistance are compatible.

6. Method for Producing Battery Pressure-Sensitive Adhesive Sheet The battery pressure-sensitive adhesive sheet 1 according to this embodiment is, for example, a laminate of the substrate 11 and the hard coat layer 12 and a laminate of the coating of the adhesive composition P and the release sheet 14 The respective bodies are prepared, and after laminating these laminates such that the hard coat layer 12 and the coating film of the adhesive composition P are in contact with each other, curing is performed, and the coating film of the adhesive composition P is It can be manufactured by forming 13. From the viewpoint of improving the adhesion between the hard coat layer 12 and the pressure-sensitive adhesive layer 13, corona treatment, plasma treatment, etc. on the surface to which one of these layers is to be bonded or the surface to which both layers are to be bonded. It is also preferable to bond the two layers after performing the surface treatment.

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

Thereafter, the layer obtained by drying the coating solution is irradiated with active energy rays to cure the layer and form the hard coat layer 12. As an active energy ray, what has an energy quantum can be used among electromagnetic waves or a charged particle beam, for example, and an ultraviolet ray, an electron beam, etc. can be used specifically ,. In particular, ultraviolet light which is easy to handle is preferable. The irradiation of the ultraviolet light can be performed by a high pressure mercury lamp, a xenon lamp or the like, and the irradiation amount of the ultraviolet light is preferably about 50 to 1000 mW / cm ^{2 of} illuminance. 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 irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation dose 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. A coating solution containing the above-mentioned adhesive composition P and optionally a solvent is applied to the release surface of the release sheet 14 and heat treatment is performed to form a coating film.

  The above heat treatment can be combined with the drying treatment at the time of volatilizing the dilution solvent and the like of the coating liquid. When heat-processing, it is preferable that heating temperature is 50-150 degreeC, and it is preferable that it is especially 70-120 degreeC. The heating time is preferably 30 seconds to 10 minutes, and more 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 bonded, curing is performed. This curing is usually performed at normal temperature (for example, 23 ° C., 50% RH) for about 1 to 2 weeks. Thereby, the coating film of the adhesive composition P turns into the adhesive layer 13, and the adhesive sheet 1 for batteries is manufactured.

  As another manufacturing method of the adhesive sheet 1 for batteries which concerns on this embodiment, you may manufacture the adhesive sheet 1 for batteries by forming the hard-coat layer 12 and the adhesive layer 13 in order on the base material 11. FIG.

Lithium-ion battery
The lithium ion battery according to one embodiment of the present invention is fixed inside the battery in a state in which two or more conductors are in contact with each other using the above-described battery pressure-sensitive adhesive sheet. Preferably, at least one of the two or more electrical conductors is in the form of a sheet and at least one is in the form of a line or a tape. Hereinafter, a lithium ion battery according to a preferred embodiment will be described.

  As shown in FIG. 2, in the lithium ion battery 2 according to this embodiment, a bottomed cylindrical exterior body 21 whose bottom portion constitutes a negative electrode terminal 23, and a positive electrode terminal 22 provided in the opening of the exterior body 21. And an electrode body 24 provided inside the exterior body 21. In addition, an electrolytic solution is enclosed in the lithium ion battery 2.

  The electrode body 24 is a sheet-like (strip-like) positive electrode current collector 241 on which the positive electrode active material layer 241 a is stacked, a negative electrode current collector 242 on which the negative electrode active material layer 242 a layer is stacked, and And an intervening separator 243. The laminate 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 laminate of the negative electrode current collector 242 and the negative electrode active material layer 242a may be referred to as a negative electrode. Sometimes called an electrode. The positive electrode, the negative electrode, and the separator 243 are respectively wound and inserted into the inside of the exterior body 21.

  Further, as shown in FIG. 3, a linear or tape-like electrode lead-out tab 244 is attached to the positive electrode current collector 241 by the above-described battery adhesive sheet 1, whereby the electrode lead-out tab 244 is It is electrically connected to the positive electrode current collector 241. The electrode extraction 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 through an electrode extraction tab (not shown).

  In general, the positive electrode current collector 241 and the negative electrode current collector 242 are made of a metal such as aluminum, and the electrode extraction tab 244 is made of a metal such as aluminum or copper.

The electrolyte used in the lithium ion battery 2 is usually a non-aqueous electrolyte. As this non-aqueous electrolyte solution, for example, one in which a lithium salt as an electrolyte is dissolved in a mixed solvent of a cyclic carbonate and a lower chain carbonate is preferably mentioned. As lithium salts, fluorine-based complex salts such as lithium hexafluorophosphate (LiPF ₆ ) and lithium borofluoride (LiBF ₄ ), LiN (SO ₂ Rf) ₂ · LiC (SO ₂ Rf) ₃ (where Rf = CF ₃ , C ₂ F ₅ ) or the like is used. Moreover, ethylene carbonate, a propylene carbonate, etc. are used as cyclic carbonate ester, Dimethyl carbonate, an ethyl methyl carbonate, a diethyl carbonate etc. are mentioned preferably as a lower chain | strand-shaped carbonate ester.

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

  In the lithium ion battery 2 according to the present embodiment, the pressure-sensitive adhesive sheet 1 for a battery is used to attach the electrode extraction tab 244 to the positive electrode current collector 241. Even when the battery pressure-sensitive adhesive sheet 1 is immersed in the non-aqueous electrolyte solution, cohesion failure due to swelling of the pressure-sensitive adhesive layer 13 is suppressed, and the positive electrode current collector 241 and the electrode extraction tab 244 are Demonstrate excellent adhesion. In addition, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 13 does not easily dissolve in the electrolytic solution, and the pressure-sensitive adhesive does not adversely affect the battery performance.

  Furthermore, since the battery adhesive sheet 1 includes the hard coat layer 12, insulation can be ensured even when the substrate 11 and the adhesive layer 13 are carbonized.

  From the above, in the lithium ion battery 2 according to the present embodiment, deterioration in performance, malfunction, thermal runaway and short circuit caused by the pressure-sensitive adhesive sheet 1 for battery are suppressed, and temperature is large even under high current conditions. It is expected to be excellent in 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 embodiment is intended to include all design changes and equivalents that fall within the technical scope of the present invention.

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

  Hereinafter, the present invention will be more specifically described by way of 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 Base Material 40 parts by mass of dipentaerythritol hexaacrylate (a 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 Part and 60 parts by mass (solid content equivalent value; the same applies hereinafter) of organosilica sol (Nissan Chemical Co., Ltd., trade name "MEK-ST"; average particle diameter 30 nm) as inorganic filler is mixed and diluted with methyl ethyl ketone Thus, a coating solution for hard coat layer was prepared.

The above coating solution is coated with a knife coater on one side of a polyimide film (made by Toray DuPont, trade name "Kapton 100H", 25 μm thickness, flame resistance level V-0 of UL 94 standard) as a base material, Dry at 70 ° C. for 1 minute. Next, the coating film was cured by irradiating the coating film with ultraviolet light (illuminance 230 mW / cm ² , light quantity 510 mJ / cm ² ). Thus, a first laminate in which a hard coat layer having a thickness of 2 μm was formed on one surface of the substrate was obtained.

In the first laminate obtained, the surface of the hard coat layer was rubbed with a load of 250 g / cm ² for 10 cm for 10 cycles using steel wool # 0000 as a steel wool resistance test. As a result, it was confirmed that no abrasion by steel wool was 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 using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000.

  Next, 100 parts by mass of the (meth) acrylic acid ester polymer thus obtained, and aluminum tris (acetylacetonate) as a metal chelate-based crosslinking agent (manufactured by Soken Chemical & Co., trade name "M-5A") 1.55 A part by mass and 0.5 parts by mass of 3-glycidoxypropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") as a silane coupling agent are mixed and diluted with methyl ethyl ketone A coating solution for the agent layer was prepared.

  The resulting coating solution is coated on a release-treated surface of a release sheet (trade name “PET 251130”, manufactured by Lintec Corporation, trade name “PET 251130”) obtained by release-treating one side of a polyethylene terephthalate film with a silicone release agent, and then 1 at 120 ° C. Heated for a minute. Thereby, the 2nd laminated body by which the coating film of the adhesive composition was laminated | stacked on the peeling process surface of the peeling sheet was obtained.

3. Production of Pressure-Sensitive Adhesive Sheet for Battery The surface of the first laminate produced as described above on the hard coat layer side and the surface of the adhesive composition of the second laminate produced as described above on the coating side are bonded Then, it was aged at 23 ° C. and 50% RH for 7 days. Thereby, the adhesive sheet for batteries in which the coating film of the adhesive composition became an adhesive layer was obtained. The thickness of the pressure-sensitive adhesive layer was 7 μm. The thickness of the said adhesive layer calculated | required by calculating | requiring the total thickness of the adhesive sheet for batteries, and deducting the thickness of a 1st laminated body and the said peeling sheet from the said total thickness.

Example 2
A (meth) acrylic acid ester polymer (Tg: -44 ° C) was prepared by copolymerizing 75 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of isobornyl acrylate and 5 parts by mass of acrylic acid by a solution polymerization method. When the molecular weight of this polymer was measured using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A pressure-sensitive adhesive sheet for a battery 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 using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A pressure-sensitive adhesive sheet for a battery 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
(Meth) acrylic acid ester polymer (Tg: −58 ° C.) by copolymerizing 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 according to a solution polymerization method 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 700,000. A pressure-sensitive adhesive sheet for a battery 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 using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A pressure-sensitive adhesive sheet for a battery 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]
(Meth) acrylic acid ester polymer (Tg: -55 ° C) was prepared by copolymerizing 80 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of cyclohexyl acrylate and 5 parts by mass of acrylic acid according to a solution polymerization method. When the molecular weight of this polymer was measured using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A pressure-sensitive adhesive sheet for a battery 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 using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A pressure-sensitive adhesive sheet for a battery 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
A solution polymerization method copolymerized 95 parts by mass of 2-ethylhexyl acrylate and 5 parts by mass of acrylic acid to prepare a (meth) acrylic acid ester polymer (Tg: -65 ° C). When the molecular weight of this polymer was measured using gel permeation chromatography (GPC) described later, the weight average molecular weight (Mw) was 700,000. A pressure-sensitive adhesive sheet for a battery 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 are copolymerized by solution polymerization to obtain (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 (meth) acrylic acid ester polymer thus obtained, and aluminum tris (acetylacetonate) as a metal chelate-based crosslinking agent (manufactured by Soken Kagaku Co., Ltd., trade name "M-5A") 0.93 A part by mass and 0.5 parts by mass of 3-glycidoxypropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") as a silane coupling agent are mixed and diluted with methyl ethyl ketone A coating solution 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 coating solution for a pressure-sensitive adhesive layer was used as the coating solution for a pressure-sensitive adhesive layer.

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 solution polymerization 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-based crosslinking agent (manufactured by Soken Chemical & Co., Ltd., trade name "M-5A") 0.31 Parts by mass, 2.35 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyo Chem Co., Ltd., trade name "BHS 8515") as an isocyanate crosslinking agent, and 3-glycidoxypropylmethyldimethoxysilane (silane coupling agent) Shin-Etsu Chemical Co., Ltd. (trade name "KBM-403") 0.5 parts by mass was mixed, and diluted with methyl ethyl ketone to prepare a coating solution for an adhesive layer. A pressure-sensitive adhesive sheet for a battery was manufactured in the same manner as in Example 1, except that the obtained coating solution for a pressure-sensitive adhesive layer was used as the coating solution for a pressure-sensitive adhesive layer.

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 (meth) acrylic acid ester polymer thus obtained, and aluminum tris (acetylacetonate) as a metal chelate-based crosslinking agent (manufactured by Soken Kagaku Co., Ltd., trade name "M-5A") 0.93 A part by mass and 0.5 parts by mass of 3-glycidoxypropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "KBM-403") as a silane coupling agent are mixed and diluted with methyl ethyl ketone A coating solution 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 coating solution for a pressure-sensitive adhesive layer was used as the coating solution for a pressure-sensitive adhesive layer.

Here, the weight average molecular weight (Mw) mentioned above is the weight average molecular weight of standard polystyrene conversion measured (GPC measurement) on the following conditions using gel permeation chromatography (GPC).
<Measurement conditions>
・ GPC measuring apparatus: Tosoh Corp. HLC-8020
・ GPC column (pass in the following order): Tosoh TSK guard column HXL-H
TSK gel GMHXL (x 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C

Test Example 1 (Measurement of Gel Fraction by Immersion in Electrolytic Solution)
In the production of adhesive sheets for batteries of Examples and Comparative Examples, a release sheet in which the surface of the adhesive composition of the second laminate on the coating side and one side of the polyethylene terephthalate film were release-treated with a silicone release agent (Lintech It bonded with the peeling process side of company make and brand name "PET251130". 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 protected on both sides by a release sheet.

  The obtained measurement sheet is cut into a size of 80 mm × 80 mm, the release sheet protecting both sides of the pressure-sensitive 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 adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M1. Next, the adhesive wrapped in the polyester mesh was immersed in a preparation solution in which ethylene carbonate and diethyl carbonate were mixed in a volume ratio of 1: 1 as an electrolyte solvent at 80 ° C. for 72 hours. Thereafter, the pressure-sensitive adhesive layer is taken out, and after dissolving and removing the adhering electrolytic solution solvent by immersion in ethanol once, air drying is performed for 24 hours under the environment of temperature 23 ° C. and relative humidity 50%, and oven at 80 ° C. The mixture was allowed to dry for 12 hours. After drying, the mass was weighed using a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (%) was calculated from the equation (M2 / M1) × 100. The results are shown in Table 1.

[Test Example 2] (Measurement of adhesion before immersion in electrolyte solvent)
The adhesive force of the pressure-sensitive adhesive sheet for a battery according to this test example was measured according to JIS Z0237: 2009 except for the operation shown below.

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

[Test Example 3] (Measurement of adhesion after immersion in electrolyte solvent)
The adhesive force of the pressure-sensitive adhesive sheet for a battery according to this test example was measured according to JIS Z0237: 2009 except for the operation shown below.

  After cutting the pressure-sensitive adhesive sheets for batteries obtained in Examples and Comparative Examples to a width of 25 mm and a length of 250 mm, test pieces were obtained by peeling the release sheet. 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 under an environment of 23 ° C. and 50% RH, and then left under the same environment for 20 minutes. Then, in the state which stuck the test piece to the aluminum plate, it was made to soak at 80 degreeC for 72 hours in the preparation liquid which mixed ethylene carbonate and diethyl carbonate as an electrolyte solution solvent by 1: 1 volume ratio. Then, immediately after taking out from the preparation liquid, the adhesive strength (N / 25 mm) was measured in the same manner as described above. This measured value was taken as the adhesive strength after immersion in the electrolyte solvent. The results are shown in Table 1.

  In the above test, although the cohesive failure of the pressure-sensitive adhesive layer did not occur in the pressure-sensitive adhesive sheet for batteries of the example, the cohesive failure of the pressure-sensitive adhesive layer occurred in the pressure-sensitive adhesive sheet for battery of the comparative example.

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

  As apparent from Table 1, in the adhesive sheet for batteries of the example, cohesive failure does not occur in the adhesive layer even when immersed in an electrolytic solution solvent and electrolytic solution, and high adhesion (adhesion before immersion in electrolytic solution solvent) More than 70% of the force). Further, it was found that the pressure-sensitive adhesive of the pressure-sensitive adhesive sheet for a battery of the example exhibited a high gel fraction even after being immersed in the electrolyte solvent, and was difficult to be eluted in the electrolyte 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 extraction 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 ... Peeling sheet 2 ... Lithium ion battery 21 ... Exterior body 22 ... Positive electrode terminal 23 ... Negative electrode terminal 24 ... Electrode body 241 ... Positive electrode current collection Body 241a ... positive electrode active material layer 242 ... negative electrode current collector 242a ... negative electrode active material layer 243 ... separator 244 ... electrode extraction tab

Claims (5)

What is claimed is: 1. A pressure-sensitive adhesive sheet for a battery, comprising: a base material; and a pressure-sensitive adhesive layer laminated on one side of the base material,
The substrate is a film comprising a polymer having a nitrogen-containing ring structure in its main chain,
The pressure-sensitive adhesive layer is
The monomer unit constituting the polymer includes a (meth) acrylic acid alkyl ester having 6 or more and 20 or less carbon atoms in the alkyl group, and a monomer having a carboxy group in the molecule, and has a weight average molecular weight of 50,000 or more , Formed from a tacky composition containing a (meth) acrylic acid ester polymer having a molecular weight of 2.5 million or less,
The gel fraction of the pressure-sensitive adhesive after immersing the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer in the solvent of the non-aqueous electrolyte for 72 hours at 80 ° C. is 80% or more and 100% or less. 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 its molecule as a monomer unit constituting the polymer.   The said adhesive composition contains a metal chelate type crosslinking agent, The adhesive sheet for batteries of Claim 1 or 2 characterized by the above-mentioned.   The adhesive sheet for batteries as described in any one of Claims 1-3 in which the hard-coat layer is formed in the surface at the side of the said adhesive layer in the said base material. It fixes in the state which two or more conductors contacted in the inside of a battery using the adhesive sheet for batteries in any one of Claims 1-4. battery.

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