TWI672356B - Thermal peeling adhesive sheet - Google Patents

Abstract

The present invention provides a heat-peelable pressure-sensitive adhesive sheet (heat-peelable pressure-sensitive adhesive sheet) having an adhesive layer which is difficult for a chemical solution to penetrate.

The heat-peelable adhesive sheet of the present invention includes a first adhesive layer, a substrate, and a second adhesive layer in this order. The first adhesive layer contains an acrylic adhesive containing a (meth) acrylic polymer and thermal expansion. Microspheres, the (meth) acrylic polymer includes structural units derived from an alkyl (meth) acrylate having an alkyl group having a carbon number of 2 or more, and derived from (meth) acrylic acid having an OH group It is a structural unit of a monomer. In this (meth) acrylic polymer, the molar ratio (C / OH) of the carbon (C) of the side chain alkyl group to the OH group is 40 to 150.

Description

Thermal release adhesive sheet

The present invention relates to a heat-peelable adhesive sheet.

Conventionally, when manufacturing a substrate included in an electronic device, an adhesive sheet is attached to the substrate material for protection (for example, Patent Document 1). For example, when a copper foil is etched as a substrate material, an adhesive sheet is attached to the copper foil in order to prevent the etchant from adhering to the non-treated surface of the copper foil. When the glass substrate is surface-polished with an acid such as hydrofluoric acid, an adhesive sheet is also attached to the non-treated surface. For the adhesive sheet for this purpose, if the medicinal solution penetrates the adhesive layer of the adhesive sheet, the interface between the adhesive layer and other layers, etc., the invaded medicinal solution becomes outgassed in the subsequent steps after the medicinal solution is processed. This may be the main reason for the deterioration of the additive material in the adhesive layer. For example, as described in Patent Document 1, a problem arises in that an adhesive layer containing thermally expandable microspheres (foaming agents) added to exhibit re-peelability is an acidic or alkaline drug The liquid undergoes chemical deterioration, causing the foaming function to disappear.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-019915

The present invention has been made in order to solve the foregoing problems, and a main object thereof is to provide a heat-peelable pressure-sensitive adhesive sheet (heat-peelable type) having an adhesive layer that is difficult to penetrate into a medical solution. Adhesive sheet).

The heat-peelable adhesive sheet of the present invention includes a first adhesive layer, a substrate, and a second adhesive layer in this order. The first adhesive layer contains an acrylic adhesive containing a (meth) acrylic polymer and thermal expansion. Microspheres, the (meth) acrylic polymer includes structural units derived from an alkyl (meth) acrylate having an alkyl group having a carbon number of 2 or more, and derived from (meth) acrylic acid having an OH group It is a structural unit of a monomer. In this (meth) acrylic polymer, the molar ratio (C / OH) of the carbon (C) of the side chain alkyl group to the OH group is 40 to 150.

In one embodiment, the second adhesive layer includes the thermally expandable microspheres.

In one embodiment, the center line average surface roughness Ra of the first adhesive layer and / or the second adhesive layer is 1 μm or less.

In one embodiment, a contact angle of water with respect to the first adhesive layer and / or the second adhesive layer is 85 ° to 115 °.

In one embodiment, the first adhesive layer includes an adhesion-imparting agent, and a content ratio of the adhesion-imparting agent is 40 parts by weight or less based on 100 parts by weight of the first adhesive layer.

In one embodiment, the second adhesive layer includes an adhesion-imparting agent, and a content ratio of the adhesion-imparting agent is 40 parts by weight or less based on 100 parts by weight of the second adhesive layer.

In one embodiment, the gel fraction of the first adhesive layer and / or the second adhesive layer is 50% or more.

In one embodiment, the adhesive force at 23 ° C. when the first adhesive layer side is bonded to the polyethylene terephthalate film is 1 N / 20 mm or more.

According to another aspect of the present invention, an electronic component is provided. This electronic component is manufactured using the said thermal peeling-type adhesive sheet.

In the present invention, by forming an adhesive layer containing a (meth) acrylic polymer as a base polymer, the (meth) acrylic polymer includes a (meth) group derived from an alkyl group having a carbon number of 2 or more. ) A structural unit of an alkyl acrylate, a structural unit derived from a (meth) acrylic monomer having an OH group, and a carbon (C) of a side chain alkyl group in the (meth) acrylic polymer Molar ratio (C / OH) with OH group is set to a specific range, and a heat-peelable pressure-sensitive adhesive sheet having an adhesive layer that is difficult to penetrate into a chemical solution and has excellent adhesion can be provided. Moreover, since the adhesive sheet of this invention is provided with the adhesive layer containing a heat-expandable microsphere, it shows the outstanding peelability by heating. Furthermore, in the present invention, since the chemical solution is difficult to penetrate into the adhesive layer, it is possible to provide a thermal expansion property without impairing the thermal expansion property even in applications such as exposure to acidic or alkaline chemical solutions (for example, protection during etching). A heat-peelable pressure-sensitive adhesive sheet having both functions of microspheres and a high degree of adhesiveness and releasability.

10‧‧‧ first adhesive layer

20‧‧‧ substrate

30‧‧‧Second adhesive layer

40‧‧‧ Elastic layer

100, 200‧‧‧ Thermal Peeling Adhesive Sheet

FIG. 1 is a schematic cross-sectional view of a heat-peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a heat-peelable pressure-sensitive adhesive sheet according to another embodiment of the present invention.

A. Overall composition of heat-peelable adhesive sheet

FIG. 1 is a schematic cross-sectional view of a heat-peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention. The thermal peeling type adhesive sheet 100 includes a first adhesive layer 10, a substrate 20, and a second adhesive layer 30 in this order. The first adhesive layer 10 includes thermally expandable microspheres. The heat-expandable microspheres expand or foam by heating. Therefore, the adhesive layer containing the heat-expandable microspheres has a reduced adhesive force by heating. The heat-peelable pressure-sensitive adhesive sheet of the present invention is provided with an adhesive layer containing heat-expandable microspheres, so that even when an adherend is bonded on both sides, the adherend can be easily peeled off by heating, so that Prevent damage to the adherend. Furthermore, the thermally expandable microspheres may be contained in the second adhesive layer.

FIG. 2 is a schematic cross-sectional view of a heat-peelable pressure-sensitive adhesive sheet according to another embodiment of the present invention. The heat-peelable pressure-sensitive adhesive sheet 200 further includes an elastic layer 40. The elastic layer 40 may be adjacent to the first adhesive The adhesive layer 10 or the second adhesive layer 30 is provided. The elastic layer 40 is preferably provided adjacent to the adhesive layer containing the thermally expandable microspheres. In one embodiment, as shown in the example, the elastic layer 40 is disposed between the first adhesive layer 10 and the substrate 20. By having the elastic layer, the followability to an adherend having an uneven surface is improved. In addition, if the elastic layer is provided adjacent to the adhesive layer containing thermally expandable microspheres, deformation (expansion) in the surface direction of the adhesive layer when heated upon peeling is restricted, and deformation in the thickness direction is preferentially generated. As a result, peelability improves.

Although not shown, a release liner may be provided on the outer side of the adhesive layer for the purpose of protecting the adhesive surface before the heat-peelable adhesive sheet of the present invention is used.

When the first adhesive layer side of the heat-peelable pressure-sensitive adhesive sheet of the present invention is bonded to a polyethylene terephthalate (PET) film, the adhesive force at 23 ° C is preferably 1N / 20mm or more, more preferably 3N / 20mm to 20N / 20mm, and more preferably 4N / 20mm to 10N / 20mm. Within this range, a heat-peelable pressure-sensitive adhesive sheet useful as a temporary protection pressure-sensitive adhesive sheet can be obtained. In this specification, the adhesive force refers to an adhesive force measured by a method based on JIS Z 0237: 2000. The specific measurement method will be described later. Furthermore, the heat-peelable adhesive sheet of the present invention is an adhesive sheet whose adhesive force is reduced by heating. The so-called “adhesive force at 23 ° C.” refers to the adhesive force before the adhesive force is reduced.

B. First adhesive layer

The first adhesive layer contains an acrylic adhesive I containing a (meth) acrylic polymer as a base polymer and thermally expandable microspheres.

B-1. Acrylic Adhesive I <(Meth) acrylic polymer>

As the (meth) acrylic polymer contained in the acrylic adhesive I, an (meth) acrylic acid alkyl ester (a) having an alkyl group having 2 or more carbon atoms and an (meth) acrylic acid having an OH group can be used. Group) A polymer obtained by using an acrylic monomer (b) as a monomer component.

Specific examples of the (meth) acrylic acid alkyl ester (a) include (meth) propylene Ethyl acetate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, second butyl (meth) acrylate, (formyl) Base) tert-butyl acrylate, amyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate Ester, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, (meth) acrylic acid Undecyl ester, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, Hexadecyl (meth) acrylate, Heptadecyl (meth) acrylate, Octadecyl (meth) acrylate, Undecyl (meth) acrylate, Dimethacrylate (di) Decadecyl esters and the like. The alkyl (meth) acrylate (a) can be used alone or in combination of two or more.

The carbon number of the alkyl group which the said (meth) acrylic-acid alkylester (a) has is 2 or more as mentioned above, Preferably it is 4 or more, More preferably, it is 4-20, More preferably, it is 6-18. By using an alkyl (meth) acrylate (a) having such an alkyl group, it is possible to form an adhesive layer that is difficult for a chemical solution (for example, an acidic or basic chemical solution) to penetrate.

Specific examples of the (meth) acrylic monomer (b) having an OH group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, Hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxydecyl (meth) acrylate, hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl methacrylate Wait. As the (meth) acrylic monomer (b), carboxyl-containing compounds such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, iconic acid, maleic acid, fumaric acid, and crotonic acid can also be used. (Meth) acrylic monomer. The (meth) acrylic monomer (b) can be used alone or in combination of two or more.

The (meth) acrylic polymer contained in the above-mentioned acrylic adhesive I may also be used for the purpose of improving cohesive force, heat resistance, crosslinkability, and the like, and if necessary, it may contain an alkyl (meth) acrylate (a ) And / or (meth) acrylic monomer (b) is a structural unit corresponding to other monomers copolymerized. Examples of such monomers include: methyl (meth) acrylate; anhydride monomers such as maleic anhydride and itaconic anhydride; styrene sulfonic acid, allyl sulfonic acid, and 2- (meth) acrylamide Sulfonic acid group-containing monomers such as 2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, and (meth) acrylamidooxynaphthalenesulfonic acid; ( (Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-hydroxyl (N-substituted) fluorenamine monomers such as methpropane (meth) acrylamide; amine ethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (methyl (Meth) acrylic acid (meth) acrylic acid amino alkyl ester-based monomers such as tert-butylaminoethyl acrylate; methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, etc. Group) alkoxyalkyl acrylate monomer; N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide Maleimide-based monomers such as arsenim; N-methyl Ikonimide, N-ethyl Ikonimide, N-butyl Ikonimide, N- Ikonimine monomers such as octyl Ikonimide, N-2-ethylhexyl Ikonimide, N-cyclohexyl Ikonimide, N-Lauryl Ikonimide; N- (meth) acryloxymethylene succinimide, N- (meth) acrylfluorenyl-6-oxyhexamethylene succinimide, N- (meth) acrylfluorenyl -8-oxyoctamethylene succinimide and other succinimide-based monomers; vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine , Vinyl piperidone, vinyl pyrimidine, vinyl piperidine Vinylpyridine , Vinylpyrrole, vinylimidazole, vinyl Azole, vinyl Vinyl monomers such as phthaloline, N-vinylcarboxamide, styrene, α -methylstyrene, N-vinyl caprolactam; cyanoacrylate monomers, such as acrylonitrile and methacrylonitrile ; Epoxy-based acrylic monomers such as glycidyl (meth) acrylate; polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) Glycol acrylate monomers such as acrylate and methoxy polypropylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, polysiloxane (meth) acrylate And other acrylate monomers with heterocycles, halogen atoms, silicon atoms, etc .; hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (methyl) Base) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol Polyfunctional monomers such as hexa (meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate; isoprene Butadiene, isobutylene and other olefin-based monomers; vinyl ether, vinyl ether-based monomers. These monomer components can be used individually or in combination of 2 or more types.

The (meth) acrylic polymer contained in the above-mentioned acrylic adhesive I is an alkyl (meth) acrylate (a) having an alkyl group having 2 or more carbon atoms and an OH group by any appropriate polymerization method. It is obtained by polymerizing the (meth) acrylic monomer (b) and other monomers (c) used as necessary. The (meth) acrylic polymer thus obtained contains (meth) derived from an alkyl group having a carbon number of 2 or more (preferably 4 or more, more preferably 4 to 20, and still more preferably 6 to 18). A structural unit A of an alkyl acrylate and a structural unit B derived from a (meth) acrylic monomer having an OH group. That is, the (meth) acrylic polymer includes a structural unit A having an alkyl group having 2 or more carbon atoms in a side chain and a structural unit B having an OH group.

The content ratio of the (meth) acrylic polymer including the structural unit A and the structural unit B is 100 parts by weight, preferably 50 to 100 parts by weight, and more preferably 100 parts by weight relative to the solid content of the acrylic adhesive I. 60 to 98 parts by weight, and more preferably 65 to 90 parts by weight.

The content ratio of the structural unit A derived from the alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms is preferably 70 to 98 parts by weight relative to 100 parts by weight of the (meth) acrylic polymer. It is more preferably 80 parts by weight to 95 parts by weight, and still more preferably 85 parts by weight to 95 parts by weight.

The content ratio of the structural unit B derived from the (meth) acrylic monomer having an OH group is preferably 1 to 30 parts by weight relative to 100 parts by weight of the (meth) acrylic polymer, and more preferably 2 to 20 parts by weight, and more preferably 3 to 10 parts by weight.

In the (meth) acrylic polymer included in the above-mentioned acrylic adhesive I, the molar ratio (C / OH) of the carbon (C) of the side chain alkyl group to the OH group is preferably 40 to 150, more preferably It is 42 to 120, more preferably 50 to 100, particularly preferably 55 to 80, and most preferably 55 to 75. In addition, the above-mentioned molar ratio (C / OH) may be formed from a monomer (i.e., (meth) acrylic acid alkyl ester (a), and optionally (meth) acrylic acid methyl ester) forming a structural unit having a side chain alkyl group. The amount of the ester), the molecular weight, and the number of side chain alkyl groups, and the amount of the (meth) acrylic monomer (b) having an OH group, the molecular weight, and the number of OH groups were determined. For example, a monomer a ₁ , a monomer ₂ and a monomer a _{3 are} used as a monomer forming a structural unit having a side chain alkyl group, and a monomer b ₁ and a monomer b _{2 are} used as (meth) acrylic In the case of the monomer (b), the above-mentioned molar ratio (C / OH) can be obtained by the following formula (1).

[Number 1] {(the number of alkyl group in the monomers a ₁₎ × (a compounding amount of the monomer ₁ (g)) / (molecular weight of monomer a _1)} + {(monomer of group a ₂ number) × (the amount of monomer formulation of a ₂ (g)) / (molecular weight of monomer a _2)} + {(the number of monomers of group a ₃₎ × (the amount of monomer formulation of a ₃ (g) ) / (molecular weight of monomer a _3)} / {(number of monomer b ₁ of a hydroxyl group) × (the amount of monomer b formulations (g of ₁₎₎ / (molecular weight of monomer b _1)} + {(single The number of hydroxyl groups in the body b ₂ ) × (the blending amount of the monomer b ₂ (g)) / (the molecular weight of the monomer b ₂ )} ... (1)

In the present invention, by making the (meth) acrylic polymer as a base polymer a specific amount of an alkyl group having a carbon number of 2 or more, the polarity of the adhesive layer can be reduced, and a chemical solution (for example, acidic or acidic or Infiltration of alkaline chemicals). On the other hand, if the polarity of the adhesive layer is too low, a sufficient adhesive force cannot be obtained. However, in the present invention, the (meth) acrylic polymer further contains an OH group and the side chain alkyl group is reduced. Mol of carbon (C) and OH group The ratio (C / OH) is within the above range, and it is possible to maintain the adhesiveness and prevent the chemical solution from penetrating into the adhesive layer. The heat-peelable pressure-sensitive adhesive sheet of the present invention having the above-mentioned pressure-sensitive adhesive layer that exhibits excellent adhesiveness by containing a specific amount of OH groups can also effectively prevent a chemical solution from entering the interface between the pressure-sensitive adhesive sheet and the adherend. By preventing the penetration of the chemical solution, deterioration of the adhesive can be suppressed, and thus excellent adhesion can be maintained. In addition, since the thermally expandable microspheres in the adhesive layer can be prevented from being deteriorated by the medicinal solution, even when used in an acidic or alkaline medicinal solution, the thermal peelability is not impaired. Furthermore, the adhesive composed of the (meth) acrylic polymer is less likely to hinder the expansion or foaming of the thermally expandable microspheres. The above-mentioned thermally peelable pressure-sensitive adhesive sheet having these effects can be preferably used as a protective sheet in a step using an acidic or alkaline chemical solution such as an etching process step.

The weight average molecular weight of the above (meth) acrylic polymer (value measured by gel permeation chromatography (solvent: THF) using a calibration curve of standard polystyrene) in terms of polystyrene, preferably 10 10,000 to 3 million, more preferably 200,000 to 2.5 million, and even more preferably 300,000 to 2 million.

<Additives>

The above-mentioned acrylic pressure-sensitive adhesive I may contain any appropriate additives as necessary. Examples of the additives include a crosslinking agent, an adhesion-imparting agent, a plasticizer (for example, a trimellitate-based plasticizer, a pyromellitic-based plasticizer), a pigment, a dye, and a filler. , Anti-aging agent, conductive material, antistatic agent, ultraviolet absorber, light stabilizer, peeling adjuster, softener, surfactant, flame retardant, antioxidant, etc.

As the adhesion imparting agent, any appropriate adhesion imparting agent can be used. As the adhesion-imparting agent, for example, an adhesion-imparting resin can be used. Specific examples of the adhesion-imparting resin include rosin-based adhesion-imparting resin (for example, unmodified rosin, modified rosin, rosin phenol-based resin, rosin ester-based resin, etc.), and terpene-based adhesion-imparting resin (for example, terpene Ethylene resins, terpene phenol resins, styrene-modified terpene resins, aromatic modified terpene resins, hydrogenated terpene resins, hydrocarbon-based adhesion-imparting resins (for example, aliphatic hydrocarbon resins, Aliphatic cyclic hydrocarbon resin, aromatic hydrocarbon resin (for example, styrene resin, xylene resin, etc.), aliphatic. Aromatic petroleum resin, aliphatic. Alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, coumarone indene resins, etc., phenol-based adhesion-imparting resins (for example, alkylphenol resins, xylene formaldehyde resins, soluble phenol resins , Novolac, etc.), ketone-based adhesion-imparting resins, polyamide-based adhesion-imparting resins, epoxy-based adhesion-imparting resins, elastic-system adhesion-imparting resins, and the like. Among them, a rosin-based adhesion-imparting resin, a terpene-based adhesion-imparting resin, or a hydrocarbon-based adhesion-imparting resin (such as a styrene-based resin) is preferred. The adhesion-imparting agent can be used alone or in combination of two or more.

A commercial item can also be used for the said adhesion-imparting agent. Specific examples of the adhesion-imparting agent for commercially available products include terpene phenol resins such as "YS POLYSTAR S145", "Mighty Ace K140" manufactured by YASUHARA Chemical Company, and "TAMANOL 901" manufactured by Arakawa Chemical Company. ; Rosin phenol resins such as "SUMILITE RESIN PR-12603" manufactured by Sumitomo Bakelite, and "TAMANOL 361" manufactured by Arakawa Chemical; alkane resins such as "TAMANOL 1010R" and "TAMANOL 200N" manufactured by Arakawa Chemical Phenol resin; alicyclic saturated hydrocarbon resins such as "ARKON P-140" manufactured by Arakawa Chemical Co., Ltd.

The added amount of the adhesion imparting agent is preferably 40 parts by weight or less, more preferably 30 parts by weight or less, still more preferably 25 parts by weight or less, and still more preferably 15 parts by weight to 25 parts by weight based on 100 parts by weight of the adhesive layer. Parts by weight. Within this range, an adhesive layer having excellent adhesion and unevenness followability can be formed. If an adhesive layer having excellent unevenness followability is formed, it is possible to significantly prevent a chemical solution from entering between the adhesive layer and the adherend.

The hydroxyl value of the adhesion-imparting agent is preferably 10 mgKOH / g or more, and more preferably 40 mgKOH / g to 400 mgKOH / g. With such a range, the adhesiveness and the prevention of the invasion of the medicinal solution are taken into consideration, and the effect of the present invention becomes remarkable.

Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, and metal alkoxide-based crosslinking agents. Crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, carbodiimide crosslinking agent, An oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, an amine-based crosslinking agent, and the like. Among these, an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent is preferred.

Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; cyclopentyl diisocyanate, cyclohexyl diisocyanate, isophor Alicyclic isocyanates such as keto diisocyanate; aromatic isocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane / toluene diisocyanate Isocyanate trimer adduct (manufactured by Nippon Polyurethane Industry, trade name "CORONATE L"), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry, trade name " CORONATE HL "), isocyanurate bodies of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry, trade name" CORONATE HX "), and the like. The content of the isocyanate-based cross-linking agent can be set to any appropriate amount according to the desired adhesive force, and it is relative to 100 parts by weight of the base polymer (that is, the (meth) acrylic polymer) in the acrylic adhesive I, It is typically 0.1 to 20 parts by weight, and more preferably 0.5 to 10 parts by weight.

Examples of the epoxy-based crosslinking agent include N, N, N ', N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, and 1,3-bis (N, N-glycidyl). Glycerylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, trade name "TETRAD C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Company, trade name "Epolight 1600" ), Neopentyl glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 1500NP"), ethylene glycol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 40E"), propylene glycol Diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., trade name "Epolight 70P"), polyethylene glycol diglycidyl ether (manufactured by Nippon Oil and Fat Co., trade name "EPIOL E-400"), polypropylene glycol diglycidyl ether (Manufactured by Japan Oil & Fats Co., Ltd. (Product name "EPIOL P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX company, trade name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase ChemteX company, trade name "Denacol EX-314 "), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX, trade name" Denacol EX-512 "), sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl Glyceryl ether, diglycidyl adipate, diglycidyl phthalate, triglycidyl tris (2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, bisphenol S- Diglycidyl ether, epoxy resin having two or more epoxy groups in the molecule, and the like. The content of the epoxy-based crosslinking agent can be set to any appropriate amount according to the desired adhesive force, and is typically 0.01 to 10 parts by weight, and more preferably 0.03 parts by weight relative to 100 parts by weight of the base polymer. ~ 5 parts by weight.

B-2. Thermal expansion microspheres

The so-called thermally expandable microspheres are microspheres that can expand or foam by heating. A heat-peelable pressure-sensitive adhesive sheet having an adhesive layer containing the heat-expandable microspheres generates unevenness on the bonding surface by heating, thereby reducing the adhesive force. Therefore, when an adhesive force is required, it has sufficient adhesive force, and In the case of peeling, the peelability is excellent. As described above, in the present invention, even when exposed to an acidic or alkaline chemical solution, the thermally expandable microspheres are not easily deteriorated, and the above functions as thermally expandable microspheres can be fully exhibited.

The content ratio of the thermally expandable microspheres can be appropriately set depending on the desired reduction of the adhesive force and the like. The content ratio of the thermally expandable microspheres is 100 parts by weight of the (meth) acrylic polymer in the acrylic adhesive I, and is, for example, 1 to 150 parts by weight, preferably 10 to 130 parts by weight, It is more preferably 25 parts by weight to 100 parts by weight.

As the thermally expandable microsphere, any appropriate thermally expandable microsphere can be used. As the heat-expandable microsphere, for example, a microsphere obtained by containing a substance that is easily expanded by heating in a shell having elasticity can be used. Such thermally expandable microspheres can be used as appropriate By a method such as a coacervation method or an interfacial polymerization method.

Examples of the substance that swells easily by heating include propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, heptane, Low boiling point liquids such as octane, petroleum ether, halides of methane, and tetraalkylsilane; azodicarbonamide, etc., which is gasified by thermal decomposition.

Examples of the substance constituting the shell include a polymer composed of the following monomers: acrylonitrile, methacrylonitrile, α -chloroacrylonitrile, α -ethoxyacrylonitrile, and fumaronitrile (fumaronitrile) and other nitrile monomers; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid and other carboxylic acid monomers; vinylidene chloride; vinyl acetate; (meth) acrylic acid methyl ester Ester, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, isobutyl (meth) acrylate (Meth) acrylates such as esters, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, and β -carboxyethyl acrylate; styrene monomers such as styrene, α -methylstyrene, and chlorostyrene Body; acrylamide monomers such as acrylamide, substituted acrylamide, methacrylamide, and substituted methacrylamide. The polymer composed of these monomers may be a homopolymer or a copolymer. Examples of the copolymer include vinylidene chloride-methyl methacrylate-acrylonitrile copolymer, methyl methacrylate-acrylonitrile-methacrylonitrile copolymer, and methyl methacrylate-acrylonitrile copolymer Compounds, acrylonitrile-methacrylonitrile-Iconic acid copolymers, and the like.

As the thermally expandable microspheres, an inorganic foaming agent or an organic foaming agent may be used. Examples of the inorganic foaming agent include ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, ammonium nitrite, sodium borohydride, and various azides. Examples of the organic blowing agent include chlorofluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile, azodimethylformamide, and azodicarboxylate. Azo compounds such as barium acid; p-toluenesulfonylhydrazine, diphenylsulfonium-3,3'-disulfonylhydrazine, 4,4'-oxybis (benzenesulfonylhydrazine), allylbis (sulfonium Hydrazine) and other hydrazine-based compounds; p-toluenesulfonylaminourea, 4,4'-oxybis (benzenesulfonylaminourea) and other aminourea-based compounds; 5- Triazole compounds such as phosphono-1,2,3,4-thiatriazole; N, N'-dinitrosopentamethylenetetramine, N, N'-dimethyl-N, N'- N-nitroso compounds such as dinitroso p-xylylenediamine and the like.

As the thermally expandable microspheres, a commercially available product may be used. Specific examples of commercially available thermally expandable microspheres include the product name "Matsumoto Microsphere" (grades: F-30, F-30D, F-36D, F-36LV, F-50) manufactured by Matsumoto Oil & Fats Pharmaceutical Co., Ltd. , F-50D, F-65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), trade names made by Japan Fillite Expancel "(grades: 053-40, 031-40, 920-40, 909-80, 930-120)," DAIFOAM "(grades: H750, H850, H1100, S2320D, S2640D, M330) manufactured by Wu Yu Chemical Industry Co., Ltd. , M430, M520), "ADVANCELL" (level: EML101, EMH204, EHM301, EHM302, EHM303, EM304, EHM401, EM403, EM501) manufactured by Sekisui Chemical Industry Co., Ltd., etc.

The particle diameter of the thermally expandable microspheres before heating is preferably 0.5 μm to 80 μm, more preferably 5 μm to 45 μm, still more preferably 10 μm to 20 μm, and even more preferably 10 μm to 15 μm. Therefore, if the particle size before heating of the thermally expandable microspheres is described by an average particle diameter, it is preferably 6 μm to 45 μm, and more preferably 15 μm to 35 μm. The particle diameter and the average particle diameter are values obtained by a particle size distribution measurement method in a laser scattering method.

The thermally expandable microspheres preferably have an appropriate strength that will not break until the volume expansion ratio reaches 5 times or more, more preferably 7 times or more, and even more preferably 10 times or more. When such a thermally expandable microsphere is used, the adhesive force can be efficiently reduced by heat treatment.

B-3. Characteristics of the first adhesive layer

The thickness of the first adhesive layer is preferably 1 μm to 100 μm, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 50 μm. As described above, the first adhesive layer is a layer containing thermally expandable microspheres. Therefore, the thickness of the first adhesive layer refers to the distance from the outer surface of the first adhesive layer (the surface opposite to the substrate) to the maximum when observing the thickness direction section of the first adhesive layer. The distance to the innermost end of the thermally expandable microspheres of the substrate.

The difference (thickness-average particle diameter) between the thickness of the first adhesive layer and the average particle diameter of the thermally expandable microspheres contained in the first adhesive layer is preferably 8 μm or more, more preferably 10 μm or more, and even more preferably It is 15 μm or more, particularly preferably 20 μm or more, and most preferably 25 μm to 100 μm. Within this range, a heat-peelable pressure-sensitive adhesive sheet having an appropriate surface roughness of the first adhesive layer and a drug solution difficult to penetrate into the interface between the first adhesive layer and the adherend can be obtained.

The elastic modulus of the first adhesive layer measured by the nanoindentation method at 25 ° C is preferably 0.01 MPa to 50 MPa, more preferably 0.1 MPa to 10 MPa, and even more preferably 0.5 MPa to 5 MPa. When the elastic modulus of the adhesive layer is in the above range, a heat-peelable pressure-sensitive adhesive sheet excellent in adhesiveness, cutting properties, and step followability can be obtained. The so-called elastic modulus measured by the nano-indentation method refers to the continuous measurement of the load on the indenter and the indentation depth when the indenter is pressed into the sample during the load and unloading. From the obtained load load- The modulus of elasticity obtained by pressing the depth curve. In this specification, the so-called elastic modulus measured by the nanoindentation method means that the measurement conditions are set to load: 1mN, load. Unloading speed: 0.1 mN / s, holding time: 1 s, and elastic modulus obtained by measuring as described above.

The elastic modulus of the first adhesive layer can be adjusted by the composition of the base polymer constituting the adhesive in the adhesive layer and the like. Further, an additive may be added to the first adhesive layer to adjust the elastic modulus. For example, if beads are contained in the first adhesive layer, the elastic modulus of the adhesive layer can be increased. Examples of the beads include glass beads and resin beads. The average particle diameter of the beads is, for example, 0.01 μm to 50 μm. The added amount of the beads is, for example, 10 to 200 parts by weight, and preferably 20 to 100 parts by weight with respect to 100 parts by weight of the entire adhesive layer.

The centerline average surface roughness Ra of the bonding surface of the first adhesive layer is preferably 1 μm or less, more preferably 0.01 μm to 1 μm, still more preferably 0.03 μm to 0.8 μm, and even more preferably 0.06 μm to 0.6 μm. . If it is in this range, it is possible to obtain a chemical solution which is difficult to penetrate to the first stage. A heat-peelable adhesive sheet at the interface between an adhesive layer and an adherend. The surface roughness Ra is measured based on JIS B 0601.

The contact angle of water with respect to the first adhesive layer is preferably 85 ° to 115 °, more preferably 87 ° to 115 °, and even more preferably 90 ° to 115 °. When the contact angle of water is greater than 115 °, that is, when the hydrophobicity of the adhesive layer is high, there is a possibility that sufficient adhesive properties cannot be obtained. On the other hand, when the contact angle of water is less than 85 °, that is, when the hydrophobicity of the adhesive layer is too low, there is a possibility that the medicinal solution penetrates into the interface between the adhesive layer and the adherend.

The gel fraction of the first adhesive layer is preferably 50% or more, more preferably 52% to 99%, and still more preferably 55% to 99%. Within this range, it is possible to prevent the chemical solution from entering the adhesive layer. The gel fraction of the adhesive layer can be adjusted by controlling the composition of the base polymer constituting the adhesive, the type and content of the crosslinking agent, and the type and content of the adhesion-imparting agent. The method for measuring the gel fraction will be described later.

C. Second adhesive layer C-1. Adhesive

The second adhesive layer includes any appropriate adhesive. As the adhesive contained in the second adhesive layer, from the standpoint of adhesion, when the second adhesive layer contains thermally expandable microspheres, the expansion or development of the thermally expandable microspheres is not restricted during heating. From the viewpoint of foaming, for example, acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, and amines can be cited. Carbamate-based adhesives, styrene-diene block copolymer-based adhesives, active energy ray-curable adhesives, and the like. Moreover, the said adhesive agent can also be an adhesive agent with improved creep characteristics which mixes the hot-melt resin with a melting point of about 200 degrees C or less. Details of the creep property-improving adhesive are described in Japanese Patent Laid-Open No. 56-61468, Japanese Patent Laid-Open No. 63-17981, and the like. Among the above-mentioned adhesives, an acrylic adhesive or a rubber-based adhesive can be preferably used. In addition, the said adhesive can be used individually or in combination of 2 or more types.

As the acrylic pressure-sensitive adhesive contained in the second pressure-sensitive adhesive layer, any appropriate acrylic pressure-sensitive adhesive can be used. Examples of the acrylic adhesive include an acrylic polymer (homopolymer or copolymer) using one or two or more (meth) acrylic acid alkyl esters as monomer components as a base polymer. In one embodiment, the acrylic adhesive I described in the above item B can be used.

Examples of the rubber-based adhesive include rubber-based adhesives using the following rubber as a base polymer. The rubbers are: natural rubber; polyisoprene rubber, styrene-butadiene (SB) rubber, and styrene. -Isoprene (SI) rubber, styrene-isoprene-styrene block copolymer (SIS) rubber, styrene-butadiene-styrene block copolymer (SBS) rubber, styrene- Ethylene-butene-styrene block copolymer (SEBS) rubber, styrene-ethylene-propylene-styrene block copolymer (SEPS) rubber, styrene-ethylene-propylene block copolymer (SEP) rubber, recycled Synthetic rubbers such as rubber, butyl rubber, polyisobutylene, and modified products thereof.

As the adhesive contained in the second adhesive layer, an active energy ray-curable adhesive that can be cured (high elastic modulus) by irradiating the active energy ray can also be used. When an active energy ray hardening type adhesive is used, a heat-peelable pressure-sensitive adhesive sheet can be obtained which has low elasticity, high flexibility, and excellent handling properties when attached. When peeling is required, the active energy ray is irradiated to Can reduce adhesion. Examples of active energy rays include gamma rays, ultraviolet rays, visible rays, infrared rays (heat rays), radiofrequency waves, alpha rays, beta rays, electron beams, plasma flows, ionizing rays, and particle beams.

Examples of the resin material constituting the active energy ray-curable adhesive include ultraviolet curing systems (see Kato Kiyoshi, issued by the Comprehensive Technology Center, (1989)), light curing technology (Technical Information Association (2000)), Japan Resin materials described in Patent Publication No. 2003-292916, Japanese Patent No. 4151850, and the like. More specifically, a resin containing a polymer serving as a mother agent and an active energy ray-reactive compound (monomer or oligomer) may be mentioned. Material (R1), resin material (R2) containing an active energy ray reactive polymer, and the like.

Examples of the polymer used as the mother agent include natural rubber, polyisobutylene rubber, styrene-butadiene rubber, styrene-isoprene-styrene block copolymer rubber, recycled rubber, and butyl rubber. , Polyisobutylene rubber, nitrile rubber (NBR) and other rubber-based polymers; silicone polymers; acrylic polymers. These polymers can be used alone or in combination of two or more.

Examples of the active energy ray-reactive compound include a photoreactive monomer having a functional group having a carbon-carbon multiple bond such as an acryl group, a methacryl group, a vinyl group, an allyl group, or an ethynyl group, or a low-reactive monomer. Polymer. Specific examples of the photoreactive monomer or oligomer include trimethylolpropane tri (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, and pentaerythritol tri (methyl). Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1 2,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate and other compounds containing (meth) acrylfluorenyl group; 2 of the (meth) acrylfluorene-containing compound ~ 5-mers, etc.

In addition, as the active energy ray-reactive compound, monomers such as epoxidized butadiene, glycidyl methacrylate, acrylamide, and vinyl siloxane; or oligomers composed of the monomers can also be used. Thing. The resin material (R1) containing these compounds can be hardened by high energy rays such as ultraviolet rays and electron beams.

Further, as the active energy ray-reactive compound, a mixture of an organic salt such as an onium salt and a compound having a plurality of heterocycles in the molecule may be used. The mixture is irradiated with active energy rays (for example, ultraviolet rays, electron beams) to split the organic salt and generate ions. The ions become the starting species and cause a ring-opening reaction of the heterocyclic ring, thereby forming a three-dimensional network structure. Examples of the organic salts include sulfonium salts, sulfonium salts, antimony salts, sulfonium salts, and borate salts. Examples of the heterocyclic ring in the compound having a plurality of heterocyclic rings in the molecule include oxetan, oxetane, oxetane, episulfide, and aziridine.

Further, as the active energy ray-reactive compound, a mixture of an organic salt such as an onium salt and a compound having a plurality of heterocycles in the molecule may be used. The mixture is irradiated with active energy rays (for example, ultraviolet rays, electron beams) to split the organic salt and generate ions. The ions become the starting species and cause a ring-opening reaction of the heterocyclic ring, thereby forming a three-dimensional network structure. Examples of the organic salts include sulfonium salts, sulfonium salts, antimony salts, sulfonium salts, and borate salts. Examples of the heterocyclic ring in the compound having a plurality of heterocyclic rings in the molecule include oxetan, oxetane, oxetane, episulfide, and aziridine.

In the above-mentioned resin material (R1) containing the polymer serving as the mother agent and the active energy ray reactive compound, the content ratio of the active energy ray reactive compound is preferably 0.1 part by weight relative to 100 parts by weight of the polymer serving as the mother agent ~ 500 parts by weight, more preferably 1 to 300 parts by weight, and still more preferably 10 to 200 parts by weight.

The above-mentioned resin material (R1) containing a polymer serving as a base agent and an active energy ray-reactive compound may contain any appropriate additives as necessary. Examples of the additives include an active energy ray polymerization initiator, an active energy ray polymerization accelerator, a crosslinking agent, a plasticizer, and a vulcanizing agent. As the active energy ray polymerization initiator, any appropriate initiator can be used according to the kind of active energy ray used. The active energy ray polymerization initiator can be used alone or in combination of two or more. In the resin material (R1) containing the polymer serving as the mother agent and the active energy ray reactive compound, the content ratio of the active energy ray polymerization initiator is preferably 0.1 part by weight relative to 100 parts by weight of the polymer serving as the mother agent. ~ 10 parts by weight, more preferably 1 to 5 parts by weight.

Examples of the active energy ray-reactive polymer include polymers having a functional group having a carbon-carbon multiple bond such as acrylfluorenyl, methacrylfluorenyl, vinyl, allyl, and ethynyl. Specific examples of the polymer having an active energy ray-reactive functional group include a polymer composed of a polyfunctional (meth) acrylate; a photocationically polymerizable polymer; a polyvinyl cinnamate containing a cinnamate group Polymers; diazotized amino novolac resins; polypropylene amidamine and the like. Reactive polymer As the resin material (R2) of the compound, a mixture of an active energy ray reactive polymer having an allyl group and a compound having a thiol group can also be used. Furthermore, as long as an adhesive layer precursor having a practical hardness (viscosity) can be formed before hardening by irradiating an active energy ray (for example, when attaching a heat-peelable adhesive sheet), it has an active energy ray reaction. In addition to the polymer having a functional group, an oligomer having an active energy ray-reactive functional group may be used.

The resin material (R2) containing the active energy ray reactive polymer may further contain the active energy ray reactive compound (monomer or oligomer). The resin material (R2) containing the active energy ray-reactive polymer may contain any appropriate additives as necessary. Specific examples of the additives are the same as the additives that can be contained in the resin material (R1) containing the polymer serving as the mother agent and the active energy ray reactive compound. In the resin material (R2) containing the active energy ray reactive polymer, the content ratio of the active energy ray polymerization initiator is preferably 0.1 to 10 parts by weight relative to 100 parts by weight of the active energy ray reactive polymer. More preferably, it is 1 to 5 parts by weight.

The adhesive contained in the second adhesive layer may include any appropriate additives as needed. Examples of the additives used include the additives described in the above item B-1. The amount of the additives (adhesion imparting agent, cross-linking agent, etc.) is also preferably the amount described in item B-1. Therefore, in one embodiment, the second adhesive layer may include an adhesion-imparting agent, and the content ratio of the adhesion-imparting agent is preferably 40 parts by weight or less, and more preferably 30 parts by weight or less with respect to 100 parts by weight of the adhesive layer. It is more preferably 25 parts by weight or less, and still more preferably 3 to 25 parts by weight.

C-2. Thermal expansion microspheres

In one embodiment, the second adhesive layer further includes the thermally expandable microspheres described in item B-2. The content ratio of the heat-expandable microspheres in the second adhesive layer is 100 parts by weight with respect to the base polymer in the adhesive forming the second adhesive layer, for example, 1 to 150 parts by weight, and preferably 10 parts by weight. Parts to 130 parts by weight, and more preferably 25 parts by weight to 100 parts by weight.

C-3. Characteristics of the second adhesive layer

The thickness of the second adhesive layer is preferably 1 μm to 100 μm, more preferably 5 μm to 80 μm, and even more preferably 10 μm to 50 μm. When the second adhesive layer includes thermally expandable microspheres, the thickness of the second adhesive layer is the same as the thickness of the first adhesive layer. The thickness of the second adhesive layer is set as follows: The distance from the outer surface of the two adhesive layers (the surface opposite to the substrate) to the innermost end of the thermally expandable microsphere closest to the substrate.

When the second adhesive layer includes thermally expandable microspheres, the difference between the thickness of the second adhesive layer and the average particle diameter of the thermally expandable microspheres included in the second adhesive layer (thickness-average particle diameter) It is preferably 8 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, particularly preferably 25 μm or more, and most preferably 25 μm to 100 μm.

The elastic modulus of the second adhesive layer measured by the nanoindentation method at 25 ° C. is preferably 0.01 MPa to 50 MPa, more preferably 0.1 MPa to 10 MPa, and even more preferably 0.5 MPa to 5 MPa.

The centerline average surface roughness Ra of the bonding surface of the second adhesive layer is preferably 1 μm or less, more preferably 0.01 μm to 1 μm, still more preferably 0.03 μm to 0.8 μm, and even more preferably 0.06 μm to 0.6 μm. .

The contact angle of water to the second adhesive layer is preferably 85 ° to 115 °, more preferably 87 ° to 115 °, and even more preferably 90 ° to 115 °.

The gel fraction of the second adhesive layer is preferably 50% or more, more preferably 52% to 99%, and still more preferably 55% to 99%. Within this range, it is possible to prevent the chemical solution from entering the adhesive layer.

D. Substrate

Examples of the substrate include resin sheets, nonwoven fabrics, paper, metal foils, woven fabrics, rubber sheets, and foamed sheets. In addition, a base material composed of such a laminated body (especially a laminated body including a resin sheet) or a composite material using these plural kinds of materials as raw materials may be used. 合 Substrate. Examples of the resin constituting the resin sheet include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polyethylene (PE). ), Polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), fully aromatic polyamide (aromatic polyamide), polyimide (PI), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluororesin, polyetheretherketone (PEEK), acrylic urethane, acrylic resin (preferably UV-curing acrylic acid) Based resin) and so on. Among these, PET, PEN, PE, or PP can be preferably used from the viewpoint of acid resistance. Examples of the nonwoven fabric include nonwoven fabrics made of natural fibers having heat resistance such as nonwoven fabrics including Manila hemp; synthetic resin nonwoven fabrics such as polypropylene resin nonwoven fabric, polyethylene resin nonwoven fabric, and ester resin nonwoven fabric.

The elastic modulus of the substrate measured at 25 ° C by the nanoindentation method is preferably 10 MPa to 10 GPa. The elastic modulus of the substrate measured by the nanoindentation method at 25 ° C is more preferably 100 MPa to 5 GPa, and even more preferably 500 MPa to 5 GPa. Within this range, a heat-peelable pressure-sensitive adhesive sheet having excellent cutting properties and rationality at the time of bonding can be obtained.

The thickness of the substrate is preferably 1 μm to 1000 μm, more preferably 2 μm to 250 μm, and even more preferably 10 μm to 100 μm. Within this range, a heat-peelable pressure-sensitive adhesive sheet having excellent cutting properties and rationality at the time of bonding can be obtained.

The substrate may be subjected to a surface treatment. Examples of the surface treatment include corona treatment, chromic acid treatment, ozone exposure, flame exposure, high-voltage electric shock exposure, ionizing radiation treatment, and coating treatment using an organic coating material. If such a surface treatment is performed, the adhesion between the adhesive layer and the substrate can be improved, and the penetration of the chemical solution into the interface between the adhesive layer and the substrate can be suppressed. In particular, a coating treatment using an organic coating material is preferred because it can suppress the grabbing damage of the adhesive layer during thermal peeling.

Examples of the organic coating material include those described in Plastic Hard Coating Material II (CMC Publication, (2004)). It is preferable to use a urethane-based polymer, and it is more preferable to use a polyacrylate urethane, a polyester urethane, or these precursors. The reason is Yu: The coating of the substrate is simple, and various ones can be industrially selected and can be obtained at low cost. The urethane-based polymer is, for example, a polymer containing a reaction mixture of an isocyanate monomer and an alcoholic hydroxyl-containing monomer (for example, a hydroxyl-containing acrylic compound or a hydroxyl-containing ester compound). The organic coating material may contain a chain extender such as a polyamine, an aging inhibitor, an oxidation stabilizer, and the like as optional additives. The thickness of the organic coating layer is not particularly limited. For example, the thickness is preferably about 0.1 μm to 10 μm, preferably about 0.1 μm to 5 μm, and more preferably about 0.5 μm to 5 μm. As the organic coating material, the ARACOAT series (for example, a combination of the trade name "AP2500E" and the hardener name "CL2500") manufactured by Arakawa Chemical Industry Co., Ltd., and the trade name "NB300" manufactured by Daihichi Chemical Co., Ltd. can also be used. , Commercial products such as "HR Color".

E. Elastic layer

As described above, the heat-peelable pressure-sensitive adhesive sheet of the present invention may further include an elastic layer.

The elastic layer includes a base polymer. As the base polymer, an adhesive polymer can be used. Examples of the base polymer constituting the elastic layer include (meth) acrylic polymers; rubber polymers such as natural rubber and synthetic rubbers (such as nitrile, diene, and acrylic); polyolefins, and polymers Thermoplastic elastomers such as esters; vinyl alkyl ether polymers; silicone polymers; polyester polymers; polyamide polymers; urethane polymers; styrene-diene Block copolymers; ethylene-vinyl acetate copolymers; polyurethane-based polymers; polybutadiene; soft polyvinyl chloride; radiation-curable polymers and the like. The base polymer constituting the elastic layer may be the same as or different from the base polymer forming the adhesive layer (the first adhesive layer and / or the second adhesive layer). The elastic layer may be a foamed film formed of the base polymer. The foamed film can be obtained by any appropriate method. Furthermore, the elastic layer and the first adhesive layer (and the second adhesive layer containing thermally expandable microspheres) can be distinguished by the presence or absence of thermally expandable microspheres (the elastic layer does not contain thermally expandable microspheres).

The (meth) acrylic polymer as a base polymer constituting the elastic layer is, for example, An acrylic polymer (homopolymer or copolymer) using one or more alkyl (meth) acrylates as monomer components. Specific examples of the alkyl (meth) acrylate include alkyl (meth) acrylates having a linear or branched alkyl group having a carbon number of 20 or less. The acrylic polymer may include units corresponding to other monomer components that can be copolymerized with the alkyl (meth) acrylate. Examples of such monomer components include acrylic acid, methacrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and N-methylol. Acrylamide, acrylonitrile, methacrylonitrile, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, styrene, isoprene, butadiene, isobutylene, vinyl ether, and the like.

The above-mentioned elastic layer may contain any appropriate additives as necessary. Examples of the additive include a crosslinking agent, a vulcanizing agent, an adhesion-imparting agent, a plasticizer, a softening agent, a filler, an anti-aging agent, and the like. When a hard resin such as polyvinyl chloride is used as the base polymer, it is preferable to use a plasticizer and / or a softener in combination to form an elastic layer having desired elasticity.

The thickness of the elastic layer is preferably 3 μm to 200 μm, and more preferably 5 μm to 100 μm. If it is this range, the said function of an elastic layer can fully be exhibited.

The tensile elastic modulus of the elastic layer at 25 ° C. is preferably less than 100 MPa, more preferably 0.1 MPa to 50 MPa, and still more preferably 0.1 MPa to 10 MPa. If it is this range, the said function of an elastic layer can fully be exhibited.

F. Manufacturing method of thermal release type adhesive sheet

The heat-peelable pressure-sensitive adhesive sheet of the present invention can be produced by any appropriate method. Regarding the heat-peelable pressure-sensitive adhesive sheet of the present invention, for example, the following method can be cited: directly coating the first adhesive layer-forming composition on one surface of the substrate, and coating the second adhesive on the other surface of the substrate. A method for forming a layer composition; a method for transferring a coating layer formed by coating on any appropriate substrate to a substrate to form a first adhesive layer and a second adhesive layer, and the like. In addition, an adhesive layer containing thermally expandable microspheres can also be used in combination with an adhesive After forming an adhesive coating layer, the thermally expandable microspheres are sprinkled on the adhesive coating layer, and then the thermally expandable microspheres are embedded in the coating layer using a laminator or the like.

The composition for forming the first adhesive layer includes the acrylic adhesive I and the thermally expandable microspheres, and optionally contains any appropriate solvent. The composition for forming the second adhesive layer includes any appropriate adhesive, and optionally includes the above-mentioned thermally expandable microspheres and / or any appropriate solvent.

In the case where the heat-peelable pressure-sensitive adhesive sheet has the above-mentioned elastic layer, the elastic layer and the adhesive layer adjacent to the elastic layer may, for example, apply a composition for forming an elastic layer on a substrate, and then apply an adhesive layer for Composition. For example, an elastic layer-forming composition containing a material for forming an elastic layer (a base polymer, an additive, etc.) is coated on a substrate, and then a first adhesive-forming composition is coated on a coating layer of the composition for forming an elastic layer. Thus, the elastic layer and the first adhesive layer can be sequentially formed from the substrate side.

As a coating method of each of the above-mentioned compositions, any appropriate coating method can be adopted. For example, each layer can be formed by drying after coating. Examples of the coating method include a coating method using, for example, a multi-coater, a die coater, a gravure coater, an applicator, and the like. Examples of the drying method include natural drying and heat drying. In the case of heating and drying, the heating temperature can be set to any appropriate temperature according to the characteristics of the substance to be dried.

G. Uses

The heat-peelable pressure-sensitive adhesive sheet of the present invention can be preferably used as a protective sheet when manufacturing electronic parts. In particular, when an electronic part is processed (for example, an etching process) using an acidic or alkaline chemical solution, it can be preferably used as a protective sheet for protecting the electronic part.

The heat-peeling type adhesive sheet of the present invention is a double-sided adhesive sheet. The electronic parts can be prevented from warping due to the two parts of the adhesive sheet sticking together as an electronic part to be processed, and the electronic part is provided in a processing step. . Further, by performing the processing steps in the above-mentioned manner, it is possible to improve production efficiency.

[Example]

Hereinafter, the present invention will be specifically described by examples, but the present invention is not limited by these examples. In the examples, "parts" and "%" are based on weight unless otherwise specified.

[Production Example 1] Preparation of acrylic adhesive I (i)

100 parts by weight of (meth) acrylic polymer (copolymer of butyl acrylate (BA) and acrylic acid (AA), structural unit derived from BA: structural unit derived from AA (weight ratio) = 95: 5) 0.6 parts by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Co., Ltd. under the trade name "TETRAD C") and 30 parts by weight of terpene phenol-based adhesion-imparting resin (manufactured by YASUHARA Chemical Co., Ltd. under the trade name "YS POLYSTAR T130") The mixture was mixed to prepare an acrylic adhesive I (i).

[Manufacturing Examples 2 to 9] Preparation of acrylic adhesives I (ii) to (ix)

The (meth) acrylic polymer, cross-linking agent, and adhesion-imparting resin shown in Table 1 were mixed at the compounding amounts shown in Table 1 to prepare acrylic adhesives I (ii) to (ix).

TETRAD X: Epoxy-based crosslinking agent; manufactured by Mitsubishi Gas Chemical Co., Ltd. under the trade name "TETRAD X"

CORONATE L: an isocyanate-based crosslinking agent; manufactured by Nippon Polyurethane Industry, under the trade name "CORONATE L"

SUPER ESTER A-75: Rosin-based adhesion-imparting resin; manufactured by Arakawa Chemical Industries, Ltd., trade name "SUPER ESTER A-75"

TAMANOL 200: Alkylphenol-based adhesion-imparting resin; manufactured by Arakawa Chemical Industries, Ltd., under the trade name "TAMANOL 200"

[Example 1]

130.6 parts by weight of the acrylic adhesive I (i) obtained in Production Example 1, 25 parts by weight of thermally expandable microspheres (manufactured by Matsumoto Oil and Fat Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere F-50D"), and 210 parts by weight of toluene were performed. Mixed to prepare an adhesive layer Formation composition (i).

This adhesive layer-forming composition (i) was coated on both sides of a PET film (manufactured by Toray Co., Ltd., trade name "Lumirror S10", thickness: 100 μm) to form a first adhesive layer having a thickness of 40 μm And a second adhesive layer.

Through the above operations, a heat-peelable pressure-sensitive adhesive sheet having a first adhesive layer (40 μm), a substrate (100 μm), and a second adhesive layer (40 μm) in this order was obtained.

[Example 2]

130.6 parts by weight of the acrylic adhesive I (i) obtained in Production Example 1, 30 parts by weight of thermally expandable microspheres (manufactured by Matsumoto Oil and Fat Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere F-48D"), and 210 parts by weight of toluene were performed. They were mixed to prepare a composition (ii) for forming an adhesive layer.

Further, as a composition (i) for forming an elastic layer, a mixture of 130.6 parts by weight of an acrylic adhesive I (i) and 210 parts by weight of toluene was prepared. In addition, as a composition (ii) for forming an elastic layer, a mixture of 130.1 parts by weight of the acrylic adhesive I (ii) obtained in Production Example 2 and 210 parts by weight of toluene was prepared.

A polyester film (manufactured by Mitsubishi Resin Co., Ltd., trade name "DIAFOIL", thickness: 50 µm) was sequentially coated on one side with a composition for forming an elastic layer (i) and a composition for forming an adhesive layer (ii) on one side. ) To form an elastic layer (thickness: 20 μm) and a first adhesive layer (thickness: 40 μm). Furthermore, the elastic layer forming composition (ii) and the adhesive layer forming composition (ii) were sequentially coated on the other surface of the substrate to form an elastic layer (thickness: 20 μm) and a second adhesive layer. (20 μm).

Through the above operations, a heat-peeling type adhesive having a first adhesive layer (40 μm), an elastic layer (20 μm), a substrate (50 μm), an elastic layer (20 μm), and a second adhesive layer (20 μm) in this order was obtained. sheet.

[Example 3]

151 parts by weight of the acrylic pressure-sensitive adhesive (iii) obtained in Production Example 3, and a slight thermal expansion property 40 parts by weight of a ball (manufactured by Matsumoto Grease Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere FN-100SD") and 210 parts by weight of toluene were mixed to prepare a composition (iii) for forming an adhesive layer.

Further, as the composition (iii) for forming an elastic layer, a mixture of 101 parts by weight of the acrylic adhesive I (iv) obtained in Production Example 4 and 210 parts by weight of toluene was prepared.

On one side of a PET film (manufactured by Toray Co., Ltd., trade name "Lumirror S10", thickness: 100 µm), a composition for forming an elastic layer (iii) and an adhesive layer forming composition (iii) were sequentially coated on one side of the substrate. ) To form an elastic layer (thickness: 30 μm) and a first adhesive layer (thickness: 30 μm). Furthermore, the composition (iii) for forming an elastic layer and the composition (iii) for forming an adhesive layer were sequentially coated on the other surface of the substrate to form an elastic layer (thickness: 15 μm) and a second adhesive layer. (Thickness: 20 μm).

Through the above operations, a heat-peeling type adhesive having a first adhesive layer (30 μm), an elastic layer (30 μm), a substrate (100 μm), an elastic layer (15 μm), and a second adhesive layer (20 μm) in this order was obtained. sheet.

[Example 4]

122 parts by weight of the acrylic adhesive (v) obtained in Production Example 5, 30 parts by weight of thermally expandable microspheres (manufactured by Japan Fillite, trade name "Expancel 909-DU80"), and 210 parts by weight of toluene were mixed to thereby mix A composition (iv) for forming an adhesive layer was prepared.

Further, as the composition (iv) for forming an elastic layer, a mixture of 112 parts by weight of the acrylic adhesive I (vi) obtained in Production Example 6 and 210 parts by weight of toluene was prepared.

On one side of a PET film (manufactured by Toray Co., Ltd., trade name "Lumirror S10", thickness: 50 µm) as a substrate, an elastic layer forming composition (iv) and an adhesive layer forming composition (iv) were sequentially applied. ) To form an elastic layer (thickness: 25 μm) and a first adhesive layer (thickness: 50 μm). Furthermore, the composition (iv) for forming an elastic layer and the composition (iv) for forming an adhesive layer were sequentially coated on the other surface of the substrate to form an elastic layer (thickness: 20 μm) and a second adhesive layer. (Thickness: 30 μm).

Through the above operations, a heat-peeling type adhesive having a first adhesive layer (50 μm), an elastic layer (25 μm), a substrate (50 μm), an elastic layer (20 μm), and a second adhesive layer (30 μm) in this order is obtained sheet.

[Comparative Example 1]

140.7 parts by weight of the acrylic adhesive I (vii) obtained in Production Example 7, 25 parts by weight of thermally expandable microspheres (manufactured by Matsumoto Oil and Fat Pharmaceutical Co., Ltd., trade name "Matsumoto Microsphere F-50D"), and 210 parts by weight of toluene were performed. They were mixed to prepare a composition (v) for forming an adhesive layer.

This adhesive layer-forming composition (v) was coated on both sides of a PET film (manufactured by Toray Co., Ltd., trade name "Lumirror S10", thickness: 100 μm) to form a first adhesive having a thickness of 45 μm. Layer and a second adhesive layer.

Through the above operations, a heat-peelable pressure-sensitive adhesive sheet having a first adhesive layer (45 μm), a substrate (100 μm), and a second adhesive layer (45 μm) in this order was obtained.

[Comparative Example 2]

127 parts by weight of the acrylic adhesive I (viii) obtained in Production Example 8, 30 parts by weight of thermally expandable microspheres (manufactured by Japan Fillite, trade name "Expancel 909-DU80"), and 210 parts by weight of toluene were mixed, Thus, a composition (vi) for forming an adhesive layer was prepared.

Further, as the composition (vi) for forming an elastic layer, a mixture of 117 parts by weight of the acrylic adhesive I (ix) obtained in Production Example 9 and 210 parts by weight of toluene was prepared.

A PET film (manufactured by Toray Co., Ltd., trade name “Lumirror S10”, thickness: 100 μm) was sequentially coated on one side of the PET film as a base material with an elastic layer forming composition (vi) and an adhesive layer forming composition (vi ) To form an elastic layer (thickness: 20 μm) and a first adhesive layer (thickness: 40 μm). Further, an adhesive layer-forming composition (vi) was coated on the other surface of the substrate to form a second adhesive layer (40 μm).

Through the above operations, a first adhesive layer (40 μm) and an elastic layer (20 μm), a substrate (100 μm), and a heat-peelable adhesive sheet of a second adhesive layer (40 μm).

[Evaluation]

The heat-peelable pressure-sensitive adhesive sheets obtained in the examples and comparative examples were subjected to the following evaluations. The results are shown in Table 2.

(1) Centerline average surface roughness Ra

The center line average surface roughness Ra of the first adhesive layer side was measured based on JIS B 0601. Specifically, an optical surface roughness meter (manufactured by Veeco Metrogy Group, trade name "Wyko NT9100") was used, and the measurement conditions were set as follows and measured. Table 2 shows the average values of the measured values obtained by measuring the vertical and horizontal directions five times.

(Evaluation conditions)

Sample size: 50mm × 50mm

Measurement range: 2.534mm × 1.901mm

Measurement mode: VSL

Objective lens: 2.5 times

Internal lens: 1.0x

(2) Contact angle

Using a contact angle meter (manufactured by Kyowa Interface Co., Ltd. under the trade name "CX-A"), add 2 μl of pure water droplets to the surface of the first adhesive layer at 23 ° C / 50% RH, and add 5 drops The contact angle of the droplet was measured after seconds. The average value of the measured values obtained by measuring 5 times is shown in Table 2.

(3) Gel fraction

0.1 g of an evaluation sample sampled from the first resin layer was wrapped with a mesh sheet, and was left to stand in 50 ml of toluene at room temperature for one week, and the sample was impregnated with toluene. Thereafter, the toluene-insoluble component was taken out, and dried at 70 ° C for 2 hours, and then the toluene-insoluble component after drying was weighed.

Use the following formula to calculate the weight of the sample before dipping in toluene and the weight of toluene-insoluble components The gel fraction of the resin layer was obtained.

Gel fraction (%) = [(weight of toluene-insoluble component) / (weight of sample before dipping toluene)] × 100

(4) Method for measuring adhesion

The heat-peelable pressure-sensitive adhesive sheet was cut into a width: 20 mm and a length: 140 mm. Based on JIS Z 0237 (2000), the temperature was 23 ± 2 ° C and humidity: 65 ± 5% RH. The roller was reciprocated once, and a polyethylene terephthalate film (trade name "Lumirror S-10", manufactured by Toray Co., Ltd .; thickness: 25 μm, width: 20 mm), which is an adherend, was bonded to the first On an adhesive layer. Next, a heat-peeling type adhesive sheet with an adherend was set in a tensile tester (made by Shimadzu Corporation, trade name "Shimadzu AUTOGRAPH AG-120kN") with a thermostat set at 23 ° C, and left for 30 minutes. After standing, the load at the time of peeling the adherend from the heat-peeling type adhesive sheet under the conditions of peeling angle: 180 °, peeling speed (tensile speed): 300 mm / min was measured at a temperature of 23 ° C. The maximum load (the maximum value of the load other than the peak at the beginning of the measurement), and the maximum load was used as the adhesive force (N / 20mm) of the first adhesive layer.

(5) Evaluation of medicinal solution invasion

The thermally peelable adhesive sheet was cut into a size of 50 mm × 50 mm, a silicon wafer was placed on the first adhesive layer side, and a glass plate (thickness: 1 mm) was placed on the second adhesive layer side. The temperature was 60 ° C. and the pressure was 0.5. These were compression-bonded under conditions of MPa and time of 3 minutes to prepare a sample for evaluation. Thereafter, the sample for evaluation was immersed in a nitric acid solution having a temperature of 40 ° C and a concentration of 60% by weight for 10 minutes. After immersion, the amount of invasion of the medicinal solution on the side of the first adhesive layer was evaluated based on the invasion distance of the liquid from the end of the adhesive sheet.

(6) Heat release

A sample for evaluation was prepared in the same manner as in the evaluation of the chemical liquid invasion (5) above. The sample for evaluation was heated at 130 ° C for 1 minute. Visually confirm the peeling condition of the heated silicon wafer. In Table 2, the case where the adhesive layer loses the adhesive force and the silicon wafer is peeled off is marked as ○. The case where the adhesive layer has adhesive force and the silicon wafer does not peel off is referred to as ×.

[Industrial availability]

The heat-peelable pressure-sensitive adhesive sheet of the present invention can be preferably used as a protective tape for electronic parts to be used in a processing solution such as an etching solution.

Claims (9)

A thermal peel-off type adhesive sheet, which includes a first adhesive layer, a substrate, and a second adhesive layer in this order. The first adhesive layer contains an acrylic adhesive containing a (meth) acrylic polymer and thermal expansion. Microspheres, the (meth) acrylic polymer includes structural units derived from an alkyl (meth) acrylate having an alkyl group having a carbon number of 2 or more, and derived from (meth) acrylic acid having an OH group Is a structural unit of a monomer. In the (meth) acrylic polymer, the molar ratio (C / OH) of the carbon (C) of the side chain alkyl group to the OH group is 40 to 75. The (meth) acrylic acid The weight average molecular weight of the polymer is 100,000 to 3 million. The heat-peelable pressure-sensitive adhesive sheet according to claim 1, wherein the second adhesive layer includes the thermally expandable microspheres. For example, the heat-peelable pressure-sensitive adhesive sheet of claim 1, wherein the center line average surface roughness Ra of the first adhesive layer and / or the second adhesive layer is 1 μm or less. For example, the thermally peelable pressure-sensitive adhesive sheet of claim 1, wherein the contact angle of water with respect to the first adhesive layer and / or the second adhesive layer is 85 ° to 115 °. The heat-peelable pressure-sensitive adhesive sheet according to claim 1, wherein the first adhesive layer includes an adhesion-imparting agent, and a content ratio of the adhesion-imparting agent is 40 parts by weight or less relative to 100 parts by weight of the first adhesive layer. The heat-peelable pressure-sensitive adhesive sheet according to claim 1, wherein the second adhesive layer includes an adhesion-imparting agent, and a content ratio of the adhesion-imparting agent is 40 parts by weight or less relative to 100 parts by weight of the second adhesive layer. For example, the heat-peelable pressure-sensitive adhesive sheet of claim 1, wherein the gel fraction of the first adhesive layer and / or the second adhesive layer is 50% or more. For example, the heat-peelable pressure-sensitive adhesive sheet according to claim 1, wherein the adhesive force at 23 ° C when the first adhesive layer side is bonded to a polyethylene terephthalate film is 1N / 20mm or more. An electronic component manufactured using a heat-peelable pressure-sensitive adhesive sheet according to claim 1.