KR20120119955A - Pressure-sensitive adhesive tape for electrochemical device - Google Patents

Abstract

PURPOSE: A pressure sensitive adhesive tape is provided to prevent corrosion of electric chemical devices while having excellent shear adhesion, and to prevent problems of electric chemical devices due to moisture in the adhesive tape because of extremely low absorption. CONSTITUTION: A pressure sensitive adhesive tape comprises an adhesive layer consisting of acrylic adhesive at least one side of plastic substrate. The acrylic adhesive contains acryl-based polymer. The acrylic polymer is obtained by polymerizing monomer components comprising at least (meth)acrylic acid alkylester, and hydroxy group-containing monomer. The acid value is 1.0 or less and glass transition temperature is -40 °C or less. A shear adhesive force of the adhesive tape at 23 °C is 20 20 N/cm^2 or more.

Description

Adhesive Tape for Electrochemical Devices {PRESSURE-SENSITIVE ADHESIVE TAPE FOR ELECTROCHEMICAL DEVICE}

TECHNICAL FIELD This invention relates to the adhesive tape used for the part which contacts an electrolyte solution, or the part which may contact an electrolyte solution in the assembly of the adhesive tape for electrochemical devices, especially an electrolytic capacitor and a lithium ion battery.

In the manufacturing process, the adhesive tape is used abundantly in the electrochemical device. For example, in the manufacturing process, the end portion of the lithium ion battery is fixed when the separator is prevented from penetrating by foreign substances or burrs, the peeling of the active material is prevented, and the laminated body such as the electrode plate and the separator is wound into the battery case. Adhesive tapes are used for various applications.

The adhesive tape used in the manufacturing process of an electrochemical device mainly consists of a base material and an adhesive layer. As an adhesive which forms the said adhesive layer, the acrylic polymer obtained by copolymerizing a (meth) acrylic-acid alkylester and a functional group containing monomer is often used in the point which can obtain the outstanding adhesiveness by bridge | crosslinking with an external crosslinking agent. It is because when an adhesive tape peels in electrolyte solution, an active material falls out, and the adhesive component eluted to electrolyte solution reacts with electrolyte, and electrolyte property falls and battery property falls (patent document 1 etc.).

However, even when using the adhesive tape which has the outstanding adhesiveness, it was a problem that the problem in an electrochemical device may arise and the lifetime of an electrical device may be reduced.

Japanese Patent Laid-Open No. 11-176476

Accordingly, an object of the present invention is to have an excellent adhesion, and to secure the end portion when winding an electrode body and a separator and the like into a battery case without protecting the electrode, preventing peeling of the active material, and adversely affecting the electrochemical device. It is providing the adhesive tape for electrochemical devices which can perform etc.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, in the acrylic polymer which comprises the adhesive layer of the adhesive tape used at the manufacturing process of an electrochemical device, it is a (meth) acrylic-acid alkylester and a carboxyl group-containing monomer as a functional group containing monomer ( For example, acrylic acid or the like) is often used, but at the time of polymerization, all of the carboxyl group-containing monomers are not copolymerized, and some of them remain slightly. Therefore, when an adhesive tape containing such a residual monomer is used for the assembly of the electrochemical device, It turned out that it causes corrosion of an electrochemical device.

Moreover, since the acrylic polymer obtained by copolymerizing the monomer containing a carboxyl group is high in water absorption, and it is easy to hold | maintain water in an adhesive layer, the adhesive tape which has the adhesive layer which consists of an acrylic polymer obtained by copolymerizing the monomer containing a carboxyl group especially lithium ion When used in the battery manufacturing process, the lithium ion battery has a high reactivity of the lithium salt in the electrolyte and immediately reduces and decomposes the moisture released in the electrolyte, thereby inhibiting the electrode reaction to deteriorate the battery capacity, and the carboxyl group-containing monomer is a non-aqueous electrolyte. It was found that electrolytic solution properties were deteriorated, resulting in degradation of battery performance, resulting in deterioration of battery life.

And about the acrylic polymer obtained by copolymerizing the (meth) acrylic-acid alkylester and the functional group containing monomer contained in the acrylic adhesive which forms the adhesive layer of the adhesive tape for electrochemical devices, a hydroxyl-group containing monomer is used as said functional group monomer. By limiting the amount of the carboxyl group-containing monomer used, the corrosion resistance of the electrochemical device due to the carboxyl group-containing monomer remaining in the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape can be prevented while reducing the water absorbency of the pressure-sensitive adhesive tape. It is possible to prevent the problem of the electrochemical device caused by the moisture contained in the adhesive tape itself, to achieve excellent shear adhesiveness by adjusting the glass transition temperature (Tg) of the acrylic polymer to a specific range, Adhesive tape having these characteristics As for electrochemical device it was found extremely useful. The present invention has been completed based on these facts.

That is, this invention is the adhesive tape for electrochemical devices which has the adhesive layer which consists of an acrylic adhesive on at least one surface of a plastics base material, The said acrylic adhesive contains at least a (meth) acrylic-acid alkylester and a hydroxyl group containing monomer. It provides the adhesive tape for electrochemical devices characterized by containing the acrylic polymer whose acid value obtained by superposing | polymerizing a monomer component is 1.0 or less and glass transition temperature (Tg) is -40 degreeC or more.

As said adhesive tape for electrochemical devices, it is preferable that the shear adhesive force in 23 degreeC is 20 N / cm <^2> or more.

As said acrylic adhesive, it is preferable to contain an acrylic polymer and 1-15 weight part of isocyanate type crosslinking agents with respect to 100 weight part of acrylic polymers.

The adhesive tape for an electrochemical device according to the present invention is capable of preventing corrosion of the electrochemical device while having excellent shear adhesion, and having an extremely low water absorption of the adhesive tape, which is caused by moisture contained in the adhesive tape itself. Problems with chemical devices can be avoided. Therefore, in the use of an electrochemical device, especially in the manufacture of a lithium ion battery, it is applied to a place immersed in an electrolyte solution or a place which may be in contact with an electrolyte solution, while preventing deterioration of battery performance and a decrease in battery life, It is possible to prevent penetration of the separator by burrs and the like, to prevent peeling of the active material, and to improve the insertion aptitude of the electrode in the battery case.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing which shows an example of the adhesive tape for electrochemical devices which concerns on this invention.
2 is a schematic cross-sectional view showing another example of an adhesive tape for an electrochemical device according to the present invention.
Fig. 3 is a schematic view showing an example of use of an adhesive tape for an electrochemical device according to the present invention in a lithium ion battery, in which Fig. 3-1 is a drawing before use and Fig. 3-2 is an electrode plate or the like. The figure which adhere | attached the adhesive tape for electrochemical devices which concerns on it, FIG. (3-3) is a figure which wound and fixed the winding using the adhesive tape for electrochemical devices which concerns on this invention.
It is a schematic diagram which shows the tension direction of an adhesive tape and a to-be-adhered body at the time of measuring the shear adhesive force of an adhesive tape.

EMBODIMENT OF THE INVENTION Below, embodiment of this invention is described in detail, referring drawings as needed.

FIG. 1: is a schematic sectional drawing which shows an example of the adhesive tape for electrochemical devices which concerns on this invention, and the adhesive tape 31 for electrochemical devices has a structure where the adhesive layer 2 was laminated | stacked on the single side | surface of the base material 1 .

FIG. 2 is a schematic cross-sectional view showing another example of the adhesive tape for an electrochemical device according to the present invention, wherein the adhesive tape 32 for an electrochemical device is a pressure-sensitive adhesive layer 21 on one side of the substrate 1 and the other side. Has a structure in which the pressure-sensitive adhesive layer 22 is laminated.

[Adhesive Layer]

The adhesive layer of this invention consists of an acrylic adhesive. An acrylic adhesive contains the acrylic polymer (copolymer) obtained by superposing | polymerizing the monomer component containing the (meth) acrylic-acid alkylester as a main monomer as a base monomer, and the functional group containing monomer which improves adhesiveness with the said main monomer at least.

As said (meth) acrylic-acid alkylester, For example, methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl group, isobutyl, amyl, isoamyl, hexyl, heptyl, cyclohexyl, 2-ethylhexyl, Having a linear or branched alkyl group having 30 or less carbon atoms such as octyl, isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl, octadecyl, and dodecyl group ( (Meth) acrylic-acid alkylester is mentioned. These can be used individually or in combination of 2 or more types. In addition, in this specification, "(meth) acryl" means "acryl" and / or "methacryl".

As the usage-amount of the (meth) acrylic-acid alkylester containing an alkyl group, 80 weight% or more (preferably 90 weight% or more, Especially preferably 95 weight%) with respect to the monomer component whole quantity (100 weight%) which comprises an acrylic polymer It is preferable to contain).

In this invention, since the shear adhesiveness can be improved especially, the content of the monomer component whole quantity (100 weight%) which content of the (meth) acrylic-acid alkylester which has a C3 or less linear or branched alkyl group comprises an acrylic polymer is contained. The total amount of monomer components (100% by weight) in which the content of the (meth) acrylic acid alkyl ester having 60% by weight or more (preferably 65% by weight or more) and having a linear or branched alkyl group having 5 or more carbon atoms constitutes the acrylic polymer. %) Is preferably 40% by weight or less (preferably 35% by weight or less).

In the present invention, a hydroxyl group (hydroxyl group) -containing monomer is used as the functional group-containing monomer. As a hydroxyl group (hydroxyl group) containing monomer, (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 2-hydroxypropyl, (meth) acrylic acid 3-hydroxypropyl, (meth) acrylic acid 4-hydroxy (Meth) acrylic-acid hydroxyalkyl, such as hydroxybutyl and 6-hydroxyhexyl (meth) acrylic acid, vinyl alcohol, allyl alcohol, etc. are mentioned. These can be used individually or in combination of 2 or more types.

The content of the functional group-containing monomer is, for example, about 1 to 10% by weight (among other things, about 1 to 7% by weight, especially 1 to 5% by weight, based on the total amount of the monomer components constituting the acrylic polymer (100% by weight). Degree). When content of a functional group containing monomer is less than the said range, there exists a tendency for adhesiveness to fall. On the other hand, when content of a functional group containing monomer exceeds the said range, it exists in the tendency which becomes easy to gelatinize at the time of superposition | polymerization.

The monomer component which forms the acrylic polymer of this invention may contain the other copolymerizable monomer other than the said main monomer and a functional group containing monomer. As said copolymerizable monomer, (meth) acrylamide, N, N- dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylol propane, for example (N-substituted) amide monomers such as (meth) acrylamide; Alkyl (meth) acrylate alkylaminoalkyl monomers such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate and t-butylaminoethyl (meth) acrylate; (Meth) acrylate alkoxyalkyl monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; Maleimide-based monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide; N-diisopropylethylenediamine, N-methylethylenediamine, N-methylethylenediamine, N-methylethylenediamine, N-methylethylenediamine, N-methylethylenediamine, Itaconimide-based monomers such as N, N-lauryl itaconimide; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide, etc. And succinimide monomers. These can be used individually or in combination of 2 or more types.

Further, as the copolymerizable monomer, for example, vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinyl Vinyl monomers such as midazole, vinyl oxazole, vinyl morpholine, N-vinylcarboxylic acid amides, styrene, α-methylstyrene, and N-vinyl caprolactam; Cyanoacrylate monomers such as (meth) acrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; Glycol-based acrylic ester monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate; (Meth) acrylic acid tetrahydrofurfuryl, fluorine (meth) acrylate, silicone (meth) acrylate, 2-methoxyethyl acrylate, etc. are also mentioned. These can be used individually or in combination of 2 or more types.

The monomer which can be copolymerized can be used as needed for the purpose of modification of adhesive characteristics, etc. As for the usage-amount, about 50 weight part or less is preferable with respect to 100 weight part of said (meth) acrylic-acid alkylesters from the point of stability at the time of superposition | polymerization of an acrylic polymer.

Moreover, as a monomer which can be copolymerized, the polyfunctional monomer aimed at the crosslinking of an acrylic polymer can also be used as needed. As a polyfunctional monomer, for example, hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate , Pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate And urethane acrylates. These can be used individually or in combination of 2 or more types.

As for the usage-amount of a polyfunctional monomer, 30 weight% or less is preferable with respect to 100 weight part of said (meth) acrylic-acid alkylester from the point of stability at the time of superposition | polymerization of an acrylic polymer.

The said acryl-type polymer can superpose | polymerize and manufacture said monomer component by a well-known or conventional polymerization method, For example, the polymerization method by solution polymerization method, emulsion polymerization method, block polymerization method, or active energy ray irradiation (active Energy ray polymerization method), and the like. Among them, a solution polymerization method and an active energy ray polymerization method are preferable from the viewpoint of being inexpensive while being able to form a polymer excellent in transparency and water resistance, and more preferably a solution polymerization method.

In the solution polymerization, various general solvents can be used. As such a solvent, For example, ester, such as ethyl acetate and n-butyl acetate; Aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; Alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; And organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. These can be used individually or in combination of 2 or more types.

In the case of the superposition | polymerization of the said monomer component, a polymerization initiator can be used. It does not specifically limit as said polymerization initiator, It can select from a well-known and usual thing suitably, For example, 2,2'- azobisisobutyronitrile (AIBN), 2,2'- azobis (4- Methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1 '-Azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (2,4,4-trimethylpentane), dimethyl-2,2'-azobis (2-methylpropionate), etc. Azo polymerization initiators; Benzoyl peroxide, t-butylhydroperoxide, di-t-butylperoxide, t-butylperoxybenzoate, dicumylperoxide, 1,1-bis (t-butylperoxy) -3,3,5 Oil-soluble polymerization initiators such as peroxide-based polymerization initiators such as -trimethylcyclohexane and 1,1-bis (t-butylperoxy) cyclododecane; and the like. These can be used individually or in combination of 2 or more types. The amount of the polymerization initiator to be used is not particularly limited, and may be any range that can be conventionally used as a polymerization initiator.

The acid value of the acrylic polymer of the present invention is 1.0 or less (preferably 0 to 0.8, particularly preferably 0 to 0.5). When an acid value exceeds the said range, it will become difficult to prevent corrosion of an electrochemical device. Moreover, there exists a tendency for an adhesive tape to become easy to absorb and to prevent the problem of the electrochemical device caused by the moisture contained in the adhesive tape itself. The acid value of an acrylic polymer can be controlled by adjusting the carboxyl group-containing monomer content in the monomer component which comprises an acrylic polymer.

In addition, the glass transition temperature (Tg) of the acrylic polymer of this invention is -40 degreeC or more (preferably -40--20 degreeC). When the glass transition temperature (Tg) is lower than −40 ° C., the shear adhesive force decreases, and in manufacture of a lithium ion battery, the end portion fixing is sufficiently performed when the laminate such as an electrode plate and a separator is wound and placed in a battery case. It tends to be difficult. The glass transition temperature (Tg) of an acryl-type polymer can be controlled by adjusting the carbon number of the alkyl chain contained in an acryl-type polymer.

As a molecular weight of the acrylic polymer of this invention, a weight average molecular weight is about 300000-1200000, for example, Preferably it is about 300000-1000000. When the weight average molecular weight is less than 300000, the adhesive force and cohesion force required as an adhesive layer are not obtained, and there exists a tendency for durability to fall. On the other hand, when a weight average molecular weight exceeds 1200000, problems, such as application | coating workability defect, may arise by the viscosity rise of an adhesive composition.

In addition, the weight average molecular weight (Mw) of an acrylic polymer can be measured by the gel permeation chromatography (GPC) method. More specifically, it can measure and obtain | require by the measurement conditions of the following GPC by polystyrene conversion value using a brand name "HLC-8120GPC" (made by Tosoh Corporation) as a GPC measuring apparatus.

<Measurement conditions of GPC>

Sample concentration: 0.2% by weight (tetrahydrofuran solution)

Sample injection volume: 10 μL

Eluent: tetrahydrofuran (THF)

Flow rate (flow rate): 0.6 mL / min

Column temperature (measurement temperature): 40 ° C

Column: Brand name "TSKgelSuperHM-H / H4000 / H3000 / H2000" (product of Toso Kabuki Kaisha)

Detector: Differential Refractometer (RI)

It is preferable that the acrylic polymer of this invention performs a crosslinking process by suitable crosslinking means (for example, addition of a crosslinking agent). By performing a crosslinking process, the shear adhesive force (for example, 20N / cm <^2> or more, especially 25N / cm <^2> or more, especially 30N / cm <^2> or more) can be provided to an adhesive tape further.

As said crosslinking agent, an epoxy type compound, an isocyanate type compound, a metal chelate compound, a metal alkoxide, a metal salt, an amine compound, a hydrazine compound, an aldehyde compound, etc. are mentioned, for example. These can be suitably selected and used according to the functional group contained in an acrylic polymer. In this invention, it is preferable to use an isocyanate type compound especially at the point which is excellent in the anchoring property with a plastics base material.

As an isocyanate type compound, polyfunctional isocyanate type compounds, such as a bifunctional isocyanate type compound and a trifunctional isocyanate type compound, are mentioned, for example. As a bifunctional isocyanate type compound, For example, lower aliphatic diisocyanates, such as butylene diisocyanate and hexamethylene diisocyanate; Alicyclic diisocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; And aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate. As a trifunctional isocyanate type compound, for example, a trimethylolpropane / tolylene diisocyanate trimer adduct (brand name "collonate L", the Nippon Polyurethane Co., Ltd. product), a trimethylolpropane / hexamethylene diisocyanate trimer adduct Isocyanate adducts, such as (brand name "collonate HL" and the Nippon Polyurethane Co., Ltd.), isocyanurate body of the hexamethylene diisocyanate (brand name "Colonate HX", Nippon Polyurethane Co., Ltd. product), etc. are mentioned. These can be used individually or in combination of 2 or more types.

Especially as a crosslinking agent in this invention, a trifunctional isocyanate type compound is preferable at the point which is excellent in reactivity and can harden more quickly.

As the usage-amount of the said crosslinking agent, it is about 1-15 weight part with respect to 100 weight part of said acrylic polymers, Preferably it is about 1-10 weight part. When the usage-amount of a crosslinking agent is less than the said range, crosslinking formation by a crosslinking agent may become inadequate, the cohesion force of an adhesive composition may become small, and sufficient shear adhesive force may not be obtained. On the other hand, when the usage-amount of a crosslinking agent exceeds the said range, the cohesion force of a polymer will become large too much and there exists a tendency for adhesiveness to fall.

In addition to the said acrylic polymer and a crosslinking agent, the acrylic adhesive in this invention may contain other components (for example, a tackifier, a plasticizer, a filler, antioxidant, etc.).

In the pressure-sensitive adhesive layer of the present invention, the acrylic pressure-sensitive adhesive is diluted with a solvent (for example, toluene, xylene, ethyl acetate, methyl ethyl ketone, etc.) as necessary to prepare a coating liquid, and this is directly prepared on a substrate or a suitable separator ( Release paper, etc.), and it can form by drying.

The pressure-sensitive adhesive layer of the present invention may be a single layer or a laminate of two or more layers. In the case where the pressure-sensitive adhesive layer is a laminate of two or more layers, each layer may have the same composition or may be laminated by combining layers of different compositions. In addition, when having an adhesive layer on both surfaces of a base material, those adhesive layers may have the same composition and may have a different composition.

The thickness (total thickness in the case of a laminate of two or more layers) of the pressure-sensitive adhesive layer of the present invention is 1 to 15 µm (preferably 1 to 10 µm). When the thickness of an adhesive layer is less than the said range, there exists a tendency for adhesive force to fall and an adhesive tape peels in electrolyte solution and it may cause deterioration of electrolyte solution. On the other hand, when the thickness of an adhesive layer exceeds the said range, the volume which occupies in an electrochemical device will become large too much, and there exists a tendency for it to become difficult to respond to high capacity of an electrochemical device.

[materials]

A plastic substrate is used as the substrate. As a raw material of a plastic base material, it is polyester (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate etc.), polyolefin (polyethylene, polypropylene, polymethyl pentene, ethylene propylene copolymer, for example). Etc.), polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, cellulose, fluorine resin, polyether, polyetheramide, polyethernitrile , Polyether ether ketone, polyphenylene sulfide, polystyrene resin (polystyrene and the like), polycarbonate, polyether sulfone and the like. These can be used individually or in combination of 2 or more types.

In this invention, the base material which uses resin chosen from polyolefin, such as polyester, such as a polyimide and a polyethylene terephthalate, and polypropylene, from among the points which are excellent in heat resistance is preferable.

The base material of the present invention may be a single layer or a laminate of two or more layers. When the base material is a laminate of two or more layers, each layer may have the same composition or may be laminated by combining layers of different compositions.

In addition, the surface of the substrate may be subjected to chemical or physical methods such as conventional surface treatments such as chromic acid treatment, ozone exposure, flame exposure, high pressure electric shock exposure, ionization radiation treatment, etc., in order to increase the adhesion to the pressure-sensitive adhesive layer or the like as necessary. Oxidation treatment and the like may be performed.

Although it does not specifically limit as thickness of a base material, For example, it is about 25 micrometers or less (preferably about 5-25 micrometers). When the thickness of the base material exceeds the above range, the volume occupied in the electrochemical device becomes excessively large, and it is difficult to cope with high capacity of the electrochemical device. On the other hand, when the thickness of a base material becomes too thin, there exists a possibility that the intensity | strength of an adhesive tape may run out and it may impair practicality.

[Adhesive Tape for Electrochemical Devices]

The adhesive tape for electrochemical devices which concerns on this invention has the said adhesive layer in at least one surface of the said base material. The adhesive tape for electrochemical devices which concerns on this invention can be formed by a well-known conventional method, For example, the acryl-type adhesive which comprises the said adhesive layer is a solvent (for example, toluene, xylene, ethyl acetate, Dilution using methyl ethyl ketone or the like) to prepare a coating liquid, and apply the coating liquid directly on a substrate to form an adhesive layer, or apply the coating liquid on a suitable separator (such as a peeler) to form an adhesive layer, The method of transferring (adhering) this to a base material, etc. are mentioned. In the case of transfer, voids (voids) may remain at the interface with the substrate. In this case, a heating pressurization process may be performed by an autoclave process etc., and a void may be diffused and annihilated.

A conventional coater, for example, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, a direct coater, and the like may be used for coating the coating solution.

Moreover, the adhesive tape for electrochemical devices which concerns on this invention can also be formed by the method of melt-extruding and integrating a base material raw material and the said acrylic adhesive. As the melt extrusion method, any known technique such as an inflation method or a T-die method can be used. Moreover, after extrusion molding, you may perform extending | stretching (uniaxial stretching) process to a vertical or horizontal direction, sequential or simultaneous extending | stretching (biaxial stretching) process to a longitudinal and a horizontal direction, etc. may be performed.

The adhesive tape for electrochemical devices which concerns on this invention can be bonded by pressing with respect to a to-be-adhered body at the pressure of about 0.5-10 kg / cm <^2> , for example. It does not specifically limit as temperature at the time of pressurization, For example, it is about 10-180 degreeC.

The adhesive force (for aluminum foil) after pressurization is, for example, 180 ° peeling strength (according to JIS Z 0237, for aluminum foil, peeling rate: 300 mm / min: adhesive strength before immersion) at 25 ° C. for 0.5 °. N / 10 mm or more (preferably 1.0 N / mm or more, particularly preferably 1.05 to 2.5 N / 10 mm).

Adhesive force after immersion at 60 ° C. for 8 hours in an ethylene carbonate / diethyl carbonate mixed solvent [the former / the latter (volume ratio) = 1/1] of the adhesive tape for an electrochemical device according to the present invention (to an aluminum foil ) Is, for example, 180 ° peeling adhesive force (according to JIS Z 0237, peeling temperature: 25 ° C., peeling rate: 300 mm / min: adhesive strength after immersion) with respect to aluminum foil is 0.5 N / mm or more (preferably 1.0 N) / mm or more (for example, 1.0 to 2.5N / 10mm)]. When the adhesive force to the aluminum foil after immersion is less than the said range, when using it inside a lithium ion battery, it will be easy to peel in electrolyte solution, and it will become difficult to suppress deterioration of electrolyte solution.

As shear adhesive force in 23 degreeC of the adhesive tape for electrochemical devices which concerns on this invention, it is preferable that it is ²⁰ N / cm <^2> or more (among these, 25N / cm <^2> or more especially 30N / cm <^2> or more). When the shear adhesive force at 23 ° C. is lower than the above range, in the manufacture of a lithium ion battery, it is difficult to sufficiently secure the end portion when winding a laminate such as an electrode plate and a separator into the battery case.

In the adhesive tape for electrochemical devices which concerns on this invention, a separator (peeling liner) may be provided in the adhesive layer surface from a viewpoint of protection of an adhesive layer surface, blocking prevention, etc. The separator is peeled off when the adhesive tape for an electrochemical device according to the present invention is attached to the adherend, and it is not necessary to install the separator. It does not specifically limit as a separator used, A well-known conventional release paper etc. can be used. For example, the base material which has peeling layers, such as a plastic film and paper surface-treated with peeling agents, such as a silicone type, a long chain alkyl type, a fluorine type, and molybdenum sulfide type; Consisting of fluoropolymers such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene hexafluoropropylene copolymer, chlorofluoroethylene vinylidene fluoride copolymer Low adhesive substrates; Low-adhesion base materials made of nonpolar polymers such as olefin resins (for example, polyethylene, polypropylene, etc.) can be used.

When the adhesive tape for electrochemical devices which concerns on this invention is a double-sided adhesive tape, the said separator may be provided in the surface of both adhesive layers of the adhesive tape for electrochemical devices which concerns on this invention, and a back peeling layer may be provided on one adhesive surface. The separator which has is provided, and you may make the back peeling layer of a separator contact the adhesive layer surface of an opposite side by winding a sheet | seat.

The adhesive tape for electrochemical devices which concerns on this invention is used suitably for manufacture of the secondary battery in which non-aqueous electrolyte solutions, such as a lithium ion battery, are enclosed.

It does not specifically limit as said non-aqueous electrolyte solution, For example, cyclic carbonates, such as propylene carbonate (PC) and ethylene carbonate (EC), dimethyl carbonate (DMC), ethylmethyl carbonate (EMC) ) And an electrolytic solution in which lithium salts such as LiPF ₆ are dissolved as a mixed solvent with a chain carbonate such as diethyl carbonate (DEC), and an electrolyte.

A non-aqueous electrolyte secondary battery such as a lithium ion battery has a stacked electrode group in which a positive electrode plate coated with a positive electrode active material on a positive electrode core body, and a negative electrode plate coated with a negative electrode active material on a negative electrode core body are laminated through a separator, or a positive electrode A wound electrode group in which a positive electrode plate coated with a positive electrode active material on a core body and a negative electrode plate coated with a negative electrode active material on a negative electrode core face each other via a separator and wound in a spiral shape, and an electrode drawn out from the positive electrode plate and the negative electrode plate. It has a structure in which a terminal and an electrolyte are sealed in an outer can.

The adhesive tape for electrochemical devices which concerns on this invention is an object which prevents penetration of a separator by a foreign material, a burr, etc., and prevents peeling of an active material, for example in manufacture of non-aqueous electrolyte secondary batteries, such as said lithium ion battery. To the battery constituting member for the purpose of improving the insertion ability of the electrode in the battery case (for example, fixing the laminate formed of the positive electrode plate / separator / negative electrode plate, or fixing the wound body of the laminate). Can be used. The place of attachment in the battery constituent member is not particularly limited as long as it is a place where the above object can be achieved, and for example, a portion where the pole plate, the electrode terminal, the pole plate end, and the pole plate end in the separator come into contact with each other, and the coated portion of the active material The boundary part of aspiration part, the winding part of a wound electrode group, etc. are mentioned (refer FIG. 3).

<Examples>

Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.

Example 1

70 parts by weight of ethyl acrylate, 30 parts by weight of 2-ethylhexyl acrylate, 4 parts by weight of 2-hydroxyethyl acrylate, 0.1 part of 2,2'-azobisisobutyronitrile (AIBN) as an initiator, and 100 parts by weight of toluene as a solvent. In combination, N ₂ substitution was performed for 2 hours. Thereafter, polymerization was carried out at 60 ° C for 6 hours to obtain an acrylic polymer (1) having a weight average molecular weight of 400,000 and a Tg of -36.6 ° C.

The trifunctional isocyanate compound (brand name "Colonate L", Nippon Polyurethane Co., Ltd. product) was mix | blended with the obtained acrylic polymer (1) in 5 weight part with respect to solid content, and the acrylic adhesive (1) was obtained.

The obtained acrylic adhesive (1) was applied to a transparent polyimide film (trade name "Kapton 50H", manufactured by Toray DuPont Co., Ltd., thickness: 12.5 µm) so that the thickness after drying was 10 µm, and the adhesive tape (1) was dried. Got it.

Example 2

60 parts by weight of ethyl acrylate, 40 parts by weight of butyl acrylate, 2 parts by weight of 2-hydroxyethyl acrylate, 0.1 parts by weight of AIBN, and 100 parts by weight of toluene were combined to perform N ₂ substitution for 2 hours. Thereafter, polymerization was carried out at 60 ° C for 6 hours to obtain an acrylic polymer (2) having a weight average molecular weight of 500,000 and a Tg of -34.9 ° C.

The trifunctional isocyanate compound (brand name "Colonate L", Nippon Polyurethane Co., Ltd. product) was mix | blended with the obtained acrylic polymer (2) in the ratio of 4 weight with respect to solid content, and the acrylic adhesive (2) was obtained.

The obtained acrylic adhesive (2) was apply | coated and dried so that the thickness after drying might be set to 10 micrometers on transparent PET film (brand name "Lumier S10", Toray Corporation make, thickness: 25 micrometers), and the adhesive tape (2) was obtained.

Comparative Example 1

The N ₂ substituted by blending 100 parts by weight of ethyl ester as a butyl acrylate 95 parts by weight, 5 parts by weight of acrylic acid, 0.1 parts AIBN, and the solvent was subjected to 2 hours. Thereafter, polymerization was carried out at 60 ° C for 6 hours to obtain an acrylic polymer (3) having a weight average molecular weight of 1.2 million and a Tg of -50.3 ° C.

The trifunctional isocyanate compound (brand name "Colonate L", Nippon Polyurethane Co., Ltd. product) was mix | blended with the obtained acrylic polymer (3) in 0.5 weight part with respect to solid content, and the acrylic adhesive (3) was obtained.

The obtained acrylic adhesive (3) was apply | coated and dried so that the thickness after drying might be set to 10 micrometers on transparent PET film (brand name "Lumirror S10", Toray Corporation make, thickness: 25 micrometers), and the adhesive tape (3) was obtained.

Comparative Example 2

The N ₂ substitution with 2-ethylhexyl acrylate 95 parts by weight, 5 parts by weight of acrylic acid, 0.1 part AIBN blending, solvent of toluene 100 parts by weight were subjected to 2 hours. Thereafter, polymerization was carried out at 60 ° C for 6 hours to obtain an acrylic polymer (4) having a weight average molecular weight of 500,000 and a Tg of -65.2 ° C.

The trifunctional isocyanate compound (brand name "Colonate L", Nippon Polyurethane Co., Ltd. product) was mix | blended with the obtained acrylic polymer (4) in the ratio of 5 weight part with respect to solid content, and the acrylic adhesive (4) was obtained.

The obtained acrylic adhesive (4) was apply | coated and dried so that the thickness after drying might be set to 10 micrometers on transparent PET film (brand name "Lumier S10", Toray Corporation make, thickness: 25 micrometers), and the adhesive tape (4) was obtained.

In addition, the glass transition temperature (Tg) was computed by the Fox-Flory formula shown by following formula (1).

n: represents an integer of 1 or more,

W ⁿ : represents the weight ratio of each monomer, w ¹ + w ² + w ³ +... + W ⁿ = 1,

Tg ⁿ is the glass transition temperature of the homopolymer of each monomer.

In addition, the acid value was measured according to JIS K 0070-1992 (potentiometric titration method). That is, 100 mL of acetone was added to about 3 g of the dried acrylic polymer, and it stirred and dissolved. 25 mL of water was added thereto and stirred. The solution was titrated with 0.05 mol / L sodium hydroxide solution to make the acid value the mg number of potassium hydroxide required to neutralize 1 g of the acrylic polymer.

About the adhesive tape obtained by the Example and the comparative example, corrosion resistance and shear adhesive force were measured by the following method.

Corrosion Evaluation Method

The adhesive tape obtained by the Example and the comparative example was cut | disconnected in the magnitude | size of width 20mm and length 20mm, and the test piece was obtained.

After bonding the obtained test piece to copper foil (thickness: 80 micrometers), it preserve | saved for 5 days in 60 degreeC and 95% RH atmosphere. Then, the test piece bonding surface of copper foil was visually observed from the transparent base material side, and the presence or absence of corrosion was confirmed.

<Method of Measuring Shear Adhesion>

The adhesive tape obtained by the Example and the comparative example was cut | disconnected in the magnitude | size of width 20mm and length 20mm, and the test piece was obtained.

A stainless steel plate (SUS304BA, completed by sand paper No. 360) as a to-be-adhered body was reciprocated by pressing a roller of 5 kg for one reciprocation on the pressure-sensitive adhesive layer surface of the obtained test piece, and then allowed to stand at 23 ± 2 ° C. for 0.5 hour.

After standing, under conditions of temperature: 23 ± 2 ° C. and humidity: 65 ± 5% RH, the test piece and the stainless steel plate were shown in FIG. 4 at a tensile speed of 50 mm / min in different directions (in the opposite direction). The load at the time of tension (maximum load) was measured, and it was set as shear adhesive force. In addition, the measured value (unit: N / 400mm <^2> ) performed unit conversion in N / cm <^2> .

The results are summarized in Table 1 below.

1: substrate
2, 21, 22: adhesive layer
3, 31, 32: adhesive tape for electrochemical devices
4: electrode terminal
5: positive electrode plate
6: negative electrode plate
7: separator
8: active material
9: Stainless steel plate (SUS304BA) as adherend

Claims (3)

It is an adhesive tape for electrochemical devices which has the adhesive layer which consists of an acrylic adhesive on at least one surface of a plastics base material, The said acrylic adhesive superposes | polymerizes the monomer component containing a (meth) acrylic-acid alkylester and a hydroxyl group containing monomer. The obtained acid value contains 1.0 or less and the acrylic polymer whose glass transition temperature (Tg) is -40 degreeC or more, The adhesive tape for electrochemical devices characterized by the above-mentioned. The adhesive tape for electrochemical devices of Claim 1 whose shear adhesive force in 23 degreeC is 20 N / cm <^2> or more. The adhesive tape for electrochemical devices of Claim 1 or 2 in which an acrylic adhesive contains an acrylic polymer and 1-15 weight part of isocyanate type crosslinking agents with respect to 100 weight part of acrylic polymers.

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