JP2016125026A - Pressure-sensitive adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive tape having excellent thermostability, capable of successfully securing the winding edge of a capacitor element even under high temperature.SOLUTION: A pressure-sensitive adhesive tape includes a base material, and an adhesive layer arranged at least on one side of the base material. The adhesive layer includes a base polymer. The acid value of the base polymer is 45-150 mgKOH/g. In one embodiment, the base polymer is an acrylic polymer. In one embodiment, the acrylic polymer includes a constitutional unit derived from a (meth)alkyl acrylate ester having a branched alkyl group.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adhesive tape. More specifically, the present invention relates to an adhesive tape that can be used for winding a capacitor element.

  In general, a capacitor element is configured by inserting electrolytic paper between an anode foil and a cathode foil and winding it in a cylindrical shape. Conventionally, an adhesive tape has been frequently used to prevent such a capacitor element from being wound (for example, Patent Documents 1 and 2).

  In recent years, a capacitor element has been subjected to a process performed at a higher temperature than before. For example, in a reflow process, the capacitor element is heated at a higher temperature than before (for example, 260 ° C. compared to 230 ° C.). Sometimes. In addition, long-term storage at high temperatures (for example, 150 ° C.) is also required.

  In applications where higher heat resistance is required as described above, when winding is stopped with a conventional pressure-sensitive adhesive tape, there is a problem in that the capacitor element is loosened, misaligned, etc., and the capacity of the capacitor element is reduced.

JP 2008-205192 A JP 2002-249736 A

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an adhesive tape that is excellent in heat resistance and capable of satisfactorily winding a capacitor element even at high temperatures.

The pressure-sensitive adhesive tape of the present invention comprises a base material and a pressure-sensitive adhesive layer disposed on at least one side of the base material, the pressure-sensitive adhesive layer contains a base polymer, and the acid value of the base polymer is 45 mgKOH / g to 150 mgKOH. / G.
In one embodiment, the base polymer is an acrylic polymer.
In one embodiment, the acrylic polymer includes a structural unit derived from a (meth) acrylic acid alkyl ester having a branched alkyl group.
In one embodiment, carbon number of this branched alkyl group in the (meth) acrylic-acid alkylester which has the said branched alkyl group is 6-24.
In one embodiment, two or more kinds of base polymers are used as the base polymer.
In one embodiment, the acid value of the said adhesive layer is 45 mgKOH / g-250 mgKOH / g.
In one embodiment, the pressure-sensitive adhesive tape of the present invention has a shrinkage ratio of 5% or less when heated at 260 ° C. for 1 hour after being attached to an aluminum plate.
In one embodiment, the adhesive tape of the present invention has a holding force to the aluminum plate of 20 mm or less after being attached to an aluminum plate and subjected to heat treatment at 260 ° C. for 1 hour.
In one embodiment, the substrate is a heat resistant substrate.
In one embodiment, the adhesive tape of the present invention is used for fixing an electrochemical device.
In one embodiment, the pressure-sensitive adhesive tape of the present invention is used for winding a capacitor element.

  According to the present invention, by using a polymer having a specific acid value as the base polymer of the pressure-sensitive adhesive layer, it is possible to obtain a pressure-sensitive adhesive tape including a pressure-sensitive adhesive layer that is difficult to deform even at high temperatures. If the pressure-sensitive adhesive tape of the present invention is used to prevent the capacitor element from being wound, it is possible to prevent the capacitor element from being loosened or wound.

It is a schematic sectional drawing of the adhesive tape by one Embodiment of this invention.

A. Overall configuration diagram 1 of the adhesive tape is a schematic sectional view of a pressure-sensitive adhesive tape according to one embodiment of the present invention. The pressure-sensitive adhesive tape 100 includes a base material 10 and a pressure-sensitive adhesive layer 20. The pressure-sensitive adhesive layer 20 may be disposed on one side of the substrate 10 or may be disposed on both sides. For example, when the pressure-sensitive adhesive tape 100 is used for fixing an electrochemical device (for example, for winding a capacitor element), the pressure-sensitive adhesive layer 20 is disposed on one side of the substrate 10 as shown in the illustrated example. Although not shown, the adhesive tape of the present invention may be provided with a release liner on the outside of the adhesive layer for the purpose of protecting the adhesive surface until it is used.

  The adhesive strength at 23 ° C. when the adhesive tape of the present invention is attached to a polyethylene terephthalate (PET) film is preferably 0.5 N / 20 mm or more, more preferably 2 N / 20 mm to 10 N / 20 mm, Preferably it is 4N / 20mm-8N / 20mm. If it is such a range, it can be set as the adhesive tape suitable for fixation of an electrochemical device. In the present specification, the adhesive strength is an adhesive strength measured by a method according to JIS Z 0237: 2000. An adhesive tape is attached to a PET film by reciprocating a 2 kg roller and left at 23 ° C. for 30 minutes. Thereafter, the pressure-sensitive adhesive tape is peeled off and measured under the conditions of a peeling angle of 180 ° and a peeling speed (tensile speed) of 300 mm / min.

When the pressure-sensitive adhesive tape of the present invention is attached to an aluminum plate and then heat-treated at 260 ° C. for 1 hour, the shrinkage rate of the pressure-sensitive adhesive tape is preferably 5% or less, more preferably 3% or less. More preferably, it is 1% or less. Within such a range, when the adhesive tape is used for winding the capacitor element, the effect of preventing loose winding, misalignment, etc. of the capacitor element becomes significant. The above shrinkage rate is obtained by sticking an adhesive tape (30 mm × 30 mm) to an aluminum plate (surface roughness Ra: 0.2 μm) under pressure bonding conditions in which a 2 kg roller is reciprocated once at a speed of 5 mm / second, It is calculated by the following formula from the area change before and after heating when heated at 260 ° C. for 1 hour.
Shrinkage rate (%) = (1−area after heating / area before heating) × 100

  After the adhesive tape of the present invention is adhered to an aluminum plate and heat-treated at 260 ° C. for 1 hour, the holding force of the adhesive tape to the aluminum plate is preferably 20 mm or less, more preferably 10 mm or less. More preferably, it is 5 mm or less. Within such a range, when the adhesive tape is used for winding the capacitor element, the effect of preventing loose winding, misalignment, etc. of the capacitor element becomes significant. The holding force can be measured as follows. (I) Adhesive tape is attached to an aluminum plate (surface roughness Ra: 0.2 μm) under pressure bonding conditions in which a 2 kg roller is reciprocated once at a speed of 5 mm / second, and an evaluation sample (sticking area: width) 10 mm × length 20 mm), and (ii) a sample for evaluation is placed so that the length direction of the adhesive tape is vertical, and a weight of 100 g is suspended from the lower end of the adhesive tape, and (iii) 260 ° C. (Iv) Measure the length of the adhesive tape misalignment after the heat treatment, and use the misalignment length as the holding force.

  The thickness of the adhesive tape is preferably 7 μm to 100 μm, more preferably 10 μm to 100 μm, and still more preferably 20 μm to 50 μm.

  The thickness of the pressure-sensitive adhesive layer is preferably 2 μm to 100 μm, more preferably 5 μm to 50 μm, and still more preferably 10 μm to 40 μm.

  The thickness of the substrate is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm.

B. Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer contains a base polymer. The acid value of the base polymer is 45 mg KOH / g to 150 mg KOH / g.

  In the conventional pressure-sensitive adhesive tape, the pressure-sensitive adhesive layer is deformed due to shrinkage or expansion of the base material or the adherend at a high temperature, and the base material and the pressure-sensitive adhesive layer are displaced due to the deformation. And the adhesive tape itself may be misaligned. When such a conventional adhesive tape is used for winding a capacitor element, the capacitor element loosens or winds off at a high temperature (for example, a reflow process), and the capacitance of the capacitor element is reduced. On the other hand, in the pressure-sensitive adhesive tape of the present invention, by setting the acid value of the base polymer contained in the pressure-sensitive adhesive layer to 45 mgKOH / g or more, the cohesive force of the pressure-sensitive adhesive layer at high temperatures is increased, and the pressure-sensitive adhesive layer is deformed. Is prevented. If such an adhesive tape is used for winding the capacitor element, loosening, winding deviation, etc. of the capacitor element can be prevented even at high temperatures (for example, a reflow process).

  The acid value of the base polymer is preferably 45 mgKOH / g to 100 mgKOH / g, more preferably 45 mgKOH / g to 75 mgKOH / g. When the acid value of the base polymer is 45 mg KOH / g to 150 mg KOH / g, an adhesive layer having a moderate hardness and a small deformation at a high temperature as described above can be formed. The pressure-sensitive adhesive tape having such a pressure-sensitive adhesive layer is effective for preventing winding looseness of the capacitor element as described above, and is excellent in stickability. In addition, by setting the acid value of the base polymer to 150 mgKOH / g or less, when applied to an electronic component such as a capacitor element, it is possible to prevent the electrolyte from entering the interface between the adhesive layer and the base material. . A method for measuring the acid value will be described later.

  The acid value of the pressure-sensitive adhesive layer varies depending on the acid value of the base polymer and the type and amount of additives (for example, tackifier). It should be noted that “the acid value of the base polymer” and “the acid value of the pressure-sensitive adhesive layer” are different concepts. Even if the tackifier is added to increase the acid value of the pressure-sensitive adhesive layer, the effect of suppressing deformation of the pressure-sensitive adhesive layer at a high temperature is insufficient. From the viewpoint of suppressing deformation of the pressure-sensitive adhesive layer at a high temperature, by setting the “acid value of the base polymer” within the above range, an adhesive tape effective for preventing winding looseness of the capacitor element was obtained. Is one of the achievements. In addition, the acid value of an adhesive layer influences the sticking property of an adhesive tape. The acid value of the pressure-sensitive adhesive layer is preferably 45 mgKOH / g to 250 mgKOH / g, more preferably 45 mgKOH / g to 200 mgKOH / g. Within such a range, combined with the effect of specifying the acid value of the base polymer, it is possible to obtain a pressure-sensitive adhesive tape in which the effect of preventing loosening of the capacitor element and the sticking property are highly compatible.

  The elastic modulus by the nanoindentation method at 25 ° C. of the pressure-sensitive adhesive layer is preferably 0.02 MPa to 20 MPa, more preferably 0.05 MPa to 10 MPa, and further preferably 0.1 MPa to 3 MPa. The modulus of elasticity by the nanoindentation method refers to the load obtained by continuously measuring the load and depth of indentation when the indenter is pushed into the sample (adhesive surface) during loading and unloading. The elastic modulus obtained from the load-indentation depth curve. In this specification, the elastic modulus by the nanoindentation method means an elastic modulus measured as described above under the measurement conditions of load: 1 mN, load / unloading speed: 0.1 mN / s, and holding time: 1 s.

  As the base polymer, an acrylic polymer is preferably used. Examples of the acrylic polymer include an acrylic polymer containing a structural unit derived from one or more (meth) acrylic acid alkyl esters. Preferably, an acrylic polymer composed of (meth) acrylic acid alkyl ester as a main monomer and composed of the main monomer and a monomer having an acid functional group is used.

  The content ratio of the structural unit derived from the (meth) acrylic acid alkyl ester is preferably 50 parts by weight to 97 parts by weight, and more preferably 70 parts by weight to 94 parts by weight with respect to 100 parts by weight of the base polymer. .

  Preferably, the (meth) acrylic acid alkyl ester has a linear or branched alkyl group having 1 to 24 carbon atoms (more preferably 3 to 20, more preferably 6 to 18).

  Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, (meth ) Hexyl acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, eicosyl (meth) acrylate, and the like.

  In one embodiment, a (meth) acrylic acid alkyl ester having a branched alkyl group is used as the (meth) acrylic acid alkyl ester. If a (meth) acrylic acid alkyl ester having a branched alkyl group is used, a pressure-sensitive adhesive tape that does not easily soak in the electrolyte can be obtained. Carbon number of the branched alkyl group is preferably 6-24, more preferably 6-18, and still more preferably 6-12. You may use together the (meth) acrylic-acid alkylester which has a linear alkyl group, and the (meth) acrylic-acid alkylester which has a branched alkyl group. Further, as the (meth) acrylic acid alkyl ester, a (meth) acrylic acid alkyl ester having a branched alkyl group may be used alone.

  In one embodiment, the content ratio of the structural unit derived from the (meth) acrylic acid alkyl ester having a branched alkyl group in the base polymer is 100 parts by weight of the structural unit derived from the (meth) acrylic acid alkyl ester (that is, 50 parts by weight to 100 parts by weight with respect to 100 parts by weight of the total amount of (meth) acrylic acid alkyl ester having a linear alkyl group and (meth) acrylic acid alkyl ester having a branched alkyl group) is there.

  Examples of the (meth) acrylic acid alkyl ester having a branched alkyl group include, for example, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, and (meth) acrylic acid 2- Examples include ethylhexyl, isooctyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, 2-methylbutyl (meth) acrylate, and the like. Among them, preferred is 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate or isodecyl (meth) acrylate, and more preferred is 2-ethylhexyl (meth) acrylate. . (Meth) acrylic acid 2-ethylhexyl has a low glass transition temperature of the homopolymer. If such 2-ethylhexyl acrylate is used, an acrylic polymer having excellent flexibility can be obtained. As a result, a pressure-sensitive adhesive layer excellent in adhesiveness with the adherend is formed, and a pressure-sensitive adhesive tape in which the electrolytic solution is difficult to penetrate can be obtained.

  Examples of the monomer having an acid functional group include a carboxyl group-containing monomer, an acid anhydride group-containing monomer, a phosphate group-containing monomer, and a sulfonic acid group-containing monomer. The acid value of the base polymer can be controlled by adjusting the content ratio of the acid functional group.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Of these, acrylic acid is preferred. Acrylic acid has a low Tg among the carboxyl group-containing monomers. Therefore, even if the content of acrylic acid is increased in order to increase the acid value, the Tg does not become higher than other carboxyl group-containing monomers, which is advantageous from the viewpoint of adhesion to the adherend.

  Examples of the acid anhydride group-containing monomer include maleic anhydride, itaconic anhydride, and an anhydride of the carboxyl group-containing monomer.

  As said phosphate group containing monomer, 2-hydroxyethyl acryloyl phosphate etc. are mentioned, for example.

  Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth ) Acrylyloxynaphthalene sulfonic acid and the like.

  The content ratio of the structural unit derived from the monomer having an acid functional group is adjusted according to the desired acid value of the base polymer. In one embodiment, the content ratio of the structural unit derived from the monomer having an acid functional group is preferably 3 parts by weight to 30 parts by weight, more preferably 6 parts by weight to 100 parts by weight of the base polymer. 25 parts by weight, more preferably 18 parts by weight to 25 parts by weight. If it is such a range, the adhesive tape which can prevent effectively the loose winding of a capacitor | condenser element, winding shift | offset | difference, etc. can be obtained. When two or more types of base polymers are used, the above-mentioned “content ratio of structural units derived from monomers having acid functional groups” refers to structural units derived from monomers having acid functional groups contained in two or more types of base polymers. The total content is based on a total amount of 100 parts by weight of the base polymer.

  In one embodiment, 2-ethylhexyl acrylate is used as the main monomer, and acrylic acid is used as the monomer having an acid functional group. In this embodiment, the content ratio of the structural unit derived from acrylic acid is preferably 3 to 30 parts by weight, more preferably 6.5 to 25 parts by weight with respect to 100 parts by weight of the base polymer. More preferably 18 to 23 parts by weight.

  The base polymer (acrylic polymer) can be copolymerized with the (meth) acrylic acid alkyl ester and a monomer having an acid functional group as necessary for the purpose of modifying cohesion, heat resistance, crosslinkability, etc. It may contain structural units derived from other monomers. Examples of such other monomers include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, Hydroxyl group-containing monomers such as hydroxymethyl (meth) acrylate, hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl methacrylate; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (N-substituted) amide monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; aminoethyl (meth) acrylate, N, N-dimethyl (meth) acrylate (Meth) acrylic acid aminoalkyl monomers such as aminoethyl and (meth) acrylic acid t-butylaminoethyl; (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl Monomer: Maleimide monomer such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide, and the like; -Succinimide monomers such as oxyhexamethylene succinimide and N- (meth) acryloyl-8-oxyoctamethylene succinimide; vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl Vinyl monomers such as piperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic amides, styrene, α-methylstyrene, N-vinylcaprolactam; cyano such as acrylonitrile, methacrylonitrile, etc. Acrylate monomer; Epoxy group-containing acrylic monomer such as glycidyl (meth) acrylate; Polyethylene glycol (meth) acrylate, (meth) acrylic Glycol acrylic ester monomers such as acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxypolypropylene glycol; (meth) acrylic acid tetrahydrofurfuryl, fluorine (meth) acrylate, silicone (meth) acrylate, etc. Acrylic acid ester monomers having a heterocyclic ring, a halogen atom, a silicon atom, etc .; 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, a polyfunctional monomer such as urethane acrylate; isoprene, butadiene, olefin monomer isobutylene and the like; vinyl ether monomers such as vinyl ether. These monomer components may be used alone or in combination of two or more.

  The content ratio of the structural unit derived from the other monomer is preferably 20 parts by weight or less, more preferably 15 parts by weight or less, and further preferably 1 part by weight to 10 parts by weight with respect to 100 parts by weight of the base polymer. Part.

  The weight average molecular weight of the base polymer is preferably 300,000 to 2,000,000, more preferably 500,000 to 1,500,000. The weight average molecular weight can be measured by GPC (solvent: THF).

  Preferably, two or more types of base polymers are used, and more preferably two types of base polymers are used. When two or more kinds of base polymers are used, it is possible to avoid problems when only one base polymer is used (such as production limitations due to differences in monomer reaction rates). Therefore, it becomes easy to control other characteristics (for example, adhesiveness, flexibility, solvent resistance, etc.) while ensuring the effect of preventing the capacitor element from loosening.

  When using 2 or more types of base polymers (acrylic polymer), it is preferable that each base polymer contains the structural unit derived from the monomer which has an acid functional group from a viewpoint of the winding-up prevention effect improvement of a capacitor | condenser element. As the monomer having an acid functional group, a carboxyl group-containing monomer is preferable, and (meth) acrylic acid is more preferable. In one embodiment, the first base polymer and the second base polymer are used, and the content ratio of the structural unit derived from the monomer having an acid functional group in the first base polymer is the first base polymer 100. The content ratio of the structural unit derived from the monomer having an acid functional group in the second base polymer is 8 parts by weight or more (preferably 8 parts by weight to 15 parts by weight) with respect to parts by weight. It is 7 parts by weight or less (preferably 3 parts by weight to 7 parts by weight) with respect to 100 parts by weight of the polymer.

  The pressure-sensitive adhesive layer may contain any appropriate additive as required. Examples of the additive include a crosslinking agent, a tackifier, a plasticizer (for example, trimellitic acid ester plasticizer, pyromellitic acid ester plasticizer), pigment, dye, filler, anti-aging agent, conductive material. , Ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants, solvents and the like.

  Any appropriate tackifier is used as the tackifier. As the tackifier, for example, a tackifier resin is used. Specific examples of tackifying resins include rosin tackifying resins (eg, unmodified rosin, modified rosin, rosin phenolic resin, rosin ester resin, etc.), terpene tackifying resins (eg, terpene resins, terpene phenols). Resin, styrene modified terpene resin, aromatic modified terpene resin, hydrogenated terpene resin), hydrocarbon tackifier resin (for example, aliphatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, aromatic resin) Hydrocarbon resins (eg, styrene resins, xylene resins, etc.), aliphatic / aromatic petroleum resins, aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, coumarone indene resins Etc.), phenolic tackifying resins (eg, alkylphenolic resins, xyleneformaldehyde resins, resoles, novos) Tsu, etc. h), ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, such as an elastomer-based tackifying resins.

  Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, a melamine crosslinking agent, a peroxide crosslinking agent, a urea crosslinking agent, a metal alkoxide crosslinking agent, a metal chelate crosslinking agent, and a metal. Examples thereof include salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and amine-based crosslinking agents. Of these, an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent is preferable.

  Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; 2,4- Aromatic isocyanates such as tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.), tri Methylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “Coronate HL”), Isocyanate of hexamethylene diisocyanate Rate bodies (Nippon Polyurethane Industry Co., Ltd. under the trade name "Coronate HX") isocyanate adducts of the like; and the like. The content of the isocyanate-based crosslinking agent can be set to any appropriate amount depending on the desired adhesive strength, and is typically 0.1 to 20 parts by weight with respect to 100 parts by weight of the base polymer. And more preferably 0.5 to 10 parts by weight.

  Examples of the epoxy crosslinking agent include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane (Mitsubishi Gas). Manufactured by Kagaku Co., Ltd., trade name “Tetrad C”), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., trade name “Epolite 1600”), neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name “ Epolite 1500NP "), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., trade name" Epolite 40E "), propylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., trade name" Epolite 70P "), polyethylene glycol diglycidyl ether (Japan) Product name “Epiol” -400 "), polypropylene glycol diglycidyl ether (Nippon Yushi Co., Ltd., trade name" Epiol P-200 "), sorbitol polyglycidyl ether (Nagase ChemteX Corporation, trade name" Denacol EX-611 "), glycerol polyglycidyl Ether (manufactured by Nagase ChemteX Corporation, trade name “Denacol EX-314”), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX Corporation, trade name “Denacol EX-512”), sorbitan polyglycidyl ether , Trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resor Emissions diglycidyl ether, bisphenol -S- diglycidyl ether, epoxy resins having two or more epoxy groups in the molecule. The content of the epoxy-based crosslinking agent can be set to any appropriate amount depending on the desired adhesive strength, and is typically 0.01 to 10 parts by weight with respect to 100 parts by weight of the base polymer. More preferably, it is 0.03 to 5 parts by weight.

C. As the substrate the base material, for example, a resin film, kraft paper, Manila hemp paper, synthetic fiber paper, and the like. Examples of the resin constituting the resin sheet include polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), polyetherimide (PEI), polysulfone (PSF), polyetheretherketone (PEEK), and polyarylate. (PAR) and the like. The resin film may be a stretched film. Among these, polyphenylene sulfide (PPS), polyimide (PI) or polyether ether ketone (PEEK) is preferable.

  Preferably, a heat resistant substrate is used as the substrate. In addition, a heat resistant base material means the base material comprised from the material whose glass transition temperature is 70 degreeC or more. The glass transition temperature of the material constituting the heat-resistant substrate is preferably 80 ° C. or higher, more preferably 90 ° C. or higher. If a heat resistant base material is used, the shrinkage | contraction under high temperature is suppressed and the adhesive tape which is excellent in the winding loosening prevention effect of a capacitor | condenser element can be obtained. Specific examples of the heat resistant substrate include a resin film composed of polyphenylene sulfide (PPS), polyimide (PI), or polyether ether ketone (PEEK). The “glass transition temperature” is a peak of loss tangent (tan δ) that is confirmed in the DMA method (tensile method) under the conditions of a heating rate of 5 ° C./min, a sample width of 5 mm, a distance between chucks of 20 mm, and a frequency of 10 Hz. Means the temperature.

  The pressure-sensitive adhesive tape of the present invention can be produced by any appropriate method. For example, the base material can be formed by applying a composition containing the base polymer and an additive added as necessary, and then drying. Further, after the pressure-sensitive adhesive layer is formed on another support, the pressure-sensitive adhesive layer may be transferred to a substrate.

  The pressure-sensitive adhesive tape of the present invention is preferably used for fixing an electrochemical device, more preferably used for winding a capacitor element.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The evaluation methods in the examples are as follows. In Examples, unless otherwise specified, “parts” and “%” are based on weight.

(1) Acid value measurement The acid value was measured according to the potentiometric titration method prescribed | regulated to JISK0070-1992. Specifically, to 50 mL of a solvent obtained by mixing diethyl ether and ethanol at a volume ratio of 4: 1, a precisely sampled sample is added, completely dissolved, and further a phenolphthalein solution is added as an indicator, A solution for measurement was prepared. The measurement solution was subjected to potentiometric titration with a 0.1 mol / L potassium hydroxide ethanol solution, and the inflection point of the obtained titration curve was set as the end point. The acid value was determined from the following formula.
Acid value (mgKOH / g) = (B × F × 5.611) / S
B: Drop amount of 0.1 mol / L potassium hydroxide ethanol solution at the end point (mL)
F: 0.1 mol / L potassium hydroxide ethanol solution (1.0)
S: Sample collection amount (g)
When the base polymer is used as a sample, the mixed solution obtained by putting the pressure-sensitive adhesive layer into chloroform is allowed to stand for 12 hours, and then the mixed solution is filtered through a filter to have a weight average molecular weight of 10,000 or more ( The acid value was determined using the substance (measured by GPC) as a sample (base polymer).

(2) Shrinkage The shrinkage of the adhesive tape was measured as follows.
(I) An adhesive tape (30 mm × 30 mm) is pressure-bonded to an aluminum plate (surface roughness Ra: 0.2 μm) to prepare a sample for evaluation. Crimping condition: 1 reciprocation of 2 kg roller at a speed of 5 mm / sec (ii) A sample for evaluation is put into a 260 ° C. hot air dryer and left to stand for 1 hour.
(Iii) The area of the adhesive tape after heating is measured.
(Iv) Shrinkage rate (%) = (1−area after heating / area before heating) × 100.

(3) Holding power The holding power of the adhesive tape was measured as follows.
(I) An adhesive tape is pressure-bonded to an aluminum plate (surface roughness Ra: 0.2 μm) to prepare a sample for evaluation (adhesion area: width 10 mm × length 20 mm). Crimping conditions: A reciprocating sample is placed so that the length direction of the adhesive tape is up and down once at a speed of 5 mm / second with a 2 kg roller, and a weight of 100 g is suspended from the lower end of the adhesive tape.
(Iii) A heat treatment is performed at 260 ° C. for 1 hour.
(Iv) The length of the adhesive tape misalignment after the heat treatment is measured, and the length of the misalignment is defined as the holding force.

(4) Terminal peeling A sample for evaluation was produced by winding an adhesive tape (width 3 mm) around a 3.2 mmφ aluminum rod twice. The sample for evaluation was immersed in γ-butyl lactone for 3 days, and the presence or absence of peeling of the adhesive tape terminal was confirmed. Note that γ-butyllactone is a solvent frequently used as an electrolytic solution. This evaluation was performed 10 times for each example and comparative example, and Table 1 shows the number of times peeling occurred.

(5) Evaluation of loosening and winding deviation as element-stopping tape Aluminum foil was wound into a cylindrical shape without a gap, and a 3 mmφ aluminum rod was produced. This aluminum bar reproduces the capacitor element in a pseudo manner. An adhesive tape (width 3 mm) was wound around this aluminum rod twice to prevent the aluminum rod from being wound. The sample for evaluation thus prepared was allowed to stand in an environment of 260 ° C. for 1 hour, and the aluminum rod was loosened and the winding deviation was visually confirmed. For each example and comparative example, this evaluation was performed 10 times, and Table 1 shows the number of times of loosening or misalignment.

[Example 1]
A composition containing 100 parts of a copolymer polymer (base polymer) consisting of 90 parts of 2-ethylhexyl acrylate and 10 parts of acrylic acid and 1 part of an isocyanate-based crosslinking agent was prepared. This composition was applied to a base material (made of polyphenylene sulfide (PPS), thickness 25 μm) so that the thickness after drying was 20 μm, and dried to obtain an adhesive tape having an adhesive layer on the base material. . The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 73.9. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

[Example 2]
A composition containing 100 parts of a copolymer (base polymer) composed of 93 parts of 2-ethylhexyl acrylate and 7 parts of acrylic acid and 3 parts of an isocyanate-based crosslinking agent was prepared. This composition was applied to a substrate (made of polyimide (PI), thickness: 25 μm) and dried so that the thickness after drying was 20 μm, and an adhesive tape provided with an adhesive layer on the substrate was obtained. The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 51.7. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

[Example 3]
A composition containing 100 parts of a copolymer (base polymer) composed of 80 parts of 2-ethylhexyl acrylate and 20 parts of acrylic acid and 1 part of an isocyanate-based crosslinking agent was prepared. This composition was applied to a substrate (made of polyimide (PI), thickness: 25 μm) and dried so that the thickness after drying was 20 μm, and an adhesive tape provided with an adhesive layer on the substrate was obtained. The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 147.8. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

[Example 4]
30 parts of copolymer polymer (base polymer) consisting of 90 parts of 2-ethylhexyl acrylate and 10 parts of acrylic acid, 70 parts of copolymer polymer (base polymer) consisting of 95 parts of 2 ethylhexyl acrylate and 5 parts of acrylic acid, and isocyanate A composition containing 1 part of a system crosslinker was prepared. This composition was applied to a base material (made of polyphenylene sulfide (PPS), thickness 25 μm) so that the thickness after drying was 20 μm, and dried to obtain an adhesive tape having an adhesive layer on the base material. . The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 48.0. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

[Example 5]
A composition containing 100 parts of a copolymer polymer (base polymer) composed of 92 parts of butyl acrylate and 8 parts of acrylic acid, 2 parts of an isocyanate-based crosslinking agent and 20 parts of a rosin phenol-based tackifier was prepared. This composition was applied to a base material (made of polyphenylene sulfide (PPS), thickness 25 μm) so that the thickness after drying was 20 μm, and dried to obtain an adhesive tape having an adhesive layer on the base material. . The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 62.3. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

[Example 6]
A composition containing 100 parts of a copolymer polymer (base polymer) consisting of 90 parts of stearyl acrylate and 10 parts of acrylic acid and 3 parts of an isocyanate-based crosslinking agent was prepared. This composition was applied to a base material (made of polyphenylene sulfide (PPS), thickness 25 μm) so that the thickness after drying was 20 μm, and dried to obtain an adhesive tape having an adhesive layer on the base material. . The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 72.1. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

[Comparative Example 1]
A composition containing 100 parts of a copolymer polymer (base polymer) composed of 95 parts of 2-ethylhexyl acrylate and 5 parts of acrylic acid and 1 part of an isocyanate-based crosslinking agent was prepared. This composition was applied to a substrate (made of polyimide (PI), thickness: 25 μm) and dried so that the thickness after drying was 20 μm, and an adhesive tape provided with an adhesive layer on the substrate was obtained. The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 36.9. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

[Comparative Example 2]
A composition containing 100 parts of a copolymer polymer (base polymer) consisting of 75 parts of 2-ethylhexyl acrylate and 25 parts of acrylic acid and 1 part of an isocyanate-based crosslinking agent was prepared. This composition was applied to a substrate (made of polyimide (PI), thickness: 25 μm) and dried so that the thickness after drying was 20 μm, and an adhesive tape provided with an adhesive layer on the substrate was obtained. The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 184.7. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

[Comparative Example 3]
A composition containing 100 parts of a copolymer polymer (base polymer) consisting of 95 parts of 2-ethylhexyl acrylate and 5 parts of acrylic acid, 2 parts of an isocyanate-based crosslinking agent, and 50 parts of a rosin phenol-based tackifier was prepared. This composition was applied to a base material (made of polyphenylene sulfide (PPS), thickness 25 μm) so that the thickness after drying was 20 μm, and dried to obtain an adhesive tape having an adhesive layer on the base material. . The acid value of the base polymer contained in the pressure-sensitive adhesive layer was 36.9. The acid value of the pressure-sensitive adhesive layer was 50.4. The obtained adhesive tape was subjected to the above evaluations (2) to (5). The results are shown in Table 1.

  As is clear from Table 1, the adhesive tape of the present invention is suitable as a tape for winding a capacitor element. More specifically, when the acid value of the base polymer in the pressure-sensitive adhesive layer is 45 mgKOH / g or more, the capacitor element can be prevented from being loosened or wound. Further, as is apparent from the evaluation of terminal peeling, an adhesive tape having excellent sticking property can be obtained by setting the acid value of the base polymer to 150 mgKOH / g or less.

  The pressure-sensitive adhesive tape of the present invention can be suitably used as a tape for fixing an electrochemical device and winding a capacitor element.

10 Substrate 20 Adhesive layer 100 Adhesive tape

Claims (11)

A substrate and a pressure-sensitive adhesive layer disposed on at least one side of the substrate;
The pressure-sensitive adhesive layer contains a base polymer, and the acid value of the base polymer is 45 mgKOH / g to 150 mgKOH / g.
Adhesive tape.   The pressure-sensitive adhesive tape according to claim 1, wherein the base polymer is an acrylic polymer.   The pressure-sensitive adhesive tape according to claim 2, wherein the acrylic polymer contains a structural unit derived from a (meth) acrylic acid alkyl ester having a branched alkyl group.   The pressure-sensitive adhesive tape according to claim 3, wherein the branched alkyl group has 6 to 24 carbon atoms in the (meth) acrylic acid alkyl ester having the branched alkyl group.   The pressure-sensitive adhesive tape according to any one of claims 1 to 4, wherein two or more kinds of base polymers are used as the base polymer.   The pressure-sensitive adhesive tape according to any one of claims 1 to 5, wherein an acid value of the pressure-sensitive adhesive layer is 45 mgKOH / g to 250 mgKOH / g.   The adhesive tape according to any one of claims 1 to 6, which has a shrinkage ratio of 5% or less when it is heat-treated at 260 ° C for 1 hour after being attached to an aluminum plate.   The pressure-sensitive adhesive tape according to any one of claims 1 to 7, wherein the adhesive force to the aluminum plate after being attached to the aluminum plate and subjected to heat treatment at 260 ° C for 1 hour is 20 mm or less.   The pressure-sensitive adhesive tape according to any one of claims 1 to 8, wherein the base material is a heat-resistant base material.   The pressure-sensitive adhesive tape according to any one of claims 1 to 9, which is used for fixing an electrochemical device.   The pressure-sensitive adhesive tape according to any one of claims 1 to 9, which is used for winding a capacitor element.

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