TW201638263A - Heat-peelable adhesive sheet - Google Patents

Abstract

This invention provides a heat-peelable adhesive sheet (heat-peelable adhesive sheet) having an adhesive layer in which a reagent solution hardly penetrates. The heat-peelable adhesive sheet of this invention comprises, in this order, a first adhesive layer, a base material and a second adhesive layer, wherein the first adhesive layer contains an acrylic adhesive containing a (meth)acrylic polymer and a thermo-expandable microsphere, the (meth)acrylic polymer contains a structural unit derived from an alkyl (meth)acrylate having an alkyl group with 2 or more carbon atoms, and a structural unit derived from a (meth)acrylic monomer having an OH group; in the (meth)acrylic polymer, a mol ratio (C/OH) of the carbon (C) to the OH group of a side chain alkyl group is from 40 to 150.

Description

Thermal peeling adhesive sheet

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

When a substrate provided in an electronic device is manufactured, an adhesive sheet is attached to a substrate material for protection (for example, Patent Document 1). For example, when etching a copper foil as a substrate material, an adhesive sheet is attached to the copper foil in order to prevent the etching liquid from adhering to the non-treated surface of the copper foil. Further, when the glass substrate is subjected to surface polishing using an acid such as hydrofluoric acid, an adhesive sheet is also attached to the non-treated surface. For the adhesive sheet for such use, if the chemical solution penetrates into the adhesive layer of the adhesive sheet, the interface between the adhesive layer and the other layers, the invading liquid chemical becomes a gas release in the subsequent step after the chemical liquid treatment. The main reason is that it is the main cause of deterioration of the additive material in the adhesive layer. For example, there is a problem described in Patent Document 1 that the foaming agent is acidic or alkaline in an adhesive layer containing heat-expandable microspheres (foaming agent) added to exhibit removability. Chemical deterioration of the liquid causes the foaming function to disappear.

[Previous Technical Literature] [Patent Literature]

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

The present invention has been made in order to solve the above-mentioned problems, and a main object thereof is to provide a heat-peelable adhesive sheet having an adhesive layer which is difficult to penetrate into a chemical solution (thermal peeling type) Adhesive film).

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

In one embodiment, the second adhesive layer includes the heat-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, the 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 contains an adhesion-imparting agent, and the content 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 contains an adhesion-imparting agent, and the content 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 first adhesive layer and/or the second adhesive layer has a gel fraction of 50% or more.

In one embodiment, when the first adhesive layer side is bonded to the polyethylene terephthalate film, the adhesion at 23 ° C 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 above-mentioned heat-peelable adhesive sheet.

In the present invention, the (meth)acrylic polymer is derived from an alkyl group having a carbon number of 2 or more by forming an adhesive layer containing a (meth)acrylic polymer as a base polymer. a structural unit of an alkyl acrylate, and a structural unit derived from a (meth)acrylic monomer having an OH group, and a carbon of a side chain alkyl group in the (meth)acrylic polymer (C) When the molar ratio (C/OH) of the OH group is set to a specific range, it is possible to provide a heat-peelable pressure-sensitive adhesive sheet having an adhesive layer which is difficult to penetrate the chemical solution and has excellent adhesion. Moreover, since the adhesive sheet of the present invention has an adhesive layer containing heat-expandable microspheres, it exhibits excellent peelability by heating. Further, in the present invention, since it is difficult for the chemical solution to penetrate into the above-mentioned adhesive layer, it is possible to provide a heat expansion property even in applications such as exposure to an acidic or alkaline chemical solution (for example, protection for etching). A heat-peelable adhesive sheet having a function of a microsphere and a high degree of adhesion and peelability.

10‧‧‧First adhesive layer

20‧‧‧Substrate

30‧‧‧Second Adhesive Layer

40‧‧‧Elastic layer

100,200‧‧‧Hot peeling adhesive sheet

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

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

A. The overall composition of the thermal peeling adhesive sheet

Fig. 1 is a schematic cross-sectional view showing a heat-peelable pressure-sensitive adhesive sheet according to an embodiment of the present invention. The heat-peelable adhesive sheet 100 is provided with a first adhesive layer 10, a substrate 20, and a second adhesive layer 30 in this order. The first adhesive layer 10 contains heat-expandable microspheres. Since the heat-expandable microspheres expand or foam by heating, the adhesive layer containing the heat-expandable microspheres is lowered in adhesion by heating. The heat-peelable pressure-sensitive adhesive sheet of the present invention is provided with an adhesive layer containing heat-expandable microspheres, and even when the adherend is bonded to both surfaces, the adherend can be easily peeled off by heating. Prevent damage to the adherend. Further, the heat-expandable microspheres may also be included in the second adhesive layer.

Fig. 2 is a schematic cross-sectional view showing 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 can be adjacent to the first adhesive The primer layer 10 or the second adhesive layer 30 is provided. Preferably, the elastic layer 40 is provided adjacent to the adhesive layer containing the heat-expandable microspheres. In one embodiment, the elastic layer 40 is disposed between the first adhesive layer 10 and the substrate 20 as illustrated. By providing the elastic layer, the followability to the adherend having the uneven surface is improved. Further, when the elastic layer is provided adjacent to the adhesive layer containing the heat-expandable microspheres, the deformation (expansion) in the surface direction of the adhesive layer when heated at the time of peeling is restricted, and deformation in the thickness direction is preferentially caused. As a result, the peelability is improved.

Although not shown, the heat-peelable pressure-sensitive adhesive sheet of the present invention may be provided with a release liner on the outer side of the pressure-sensitive adhesive layer for the purpose of protecting the adhesive surface before being 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 adhesion at 23 ° C is preferably 1 N/20 mm or more, more preferably 3N/20mm~20N/20mm, and further preferably 4N/20mm~10N/20mm. When it is such a range, the heat-peelable adhesive sheet which is useful as a temporary protective adhesive sheet can be obtained. In the present specification, the term "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. Further, the heat-peelable adhesive sheet of the present invention is an adhesive sheet having a reduced adhesive force by heating, and the above-mentioned "adhesion force at 23 ° C" means an adhesive force before the adhesive force is lowered.

B. First adhesive layer

The first adhesive layer contains an acrylic adhesive I and a heat-expandable microsphere containing a (meth)acrylic polymer as a base polymer.

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

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

Specific examples of the alkyl (meth)acrylate (a) include (meth) propylene. Ethyl acetate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, dibutyl (meth)acrylate, (A) Base) tert-butyl acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate Ester, isooctyl (meth)acrylate, decyl (meth)acrylate, isodecyl (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, Cetyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, hexadecyl (meth) acrylate, (meth) acrylate Decaalkyl ester and the like. The alkyl (meth)acrylate (a) may be used singly or in combination of two or more.

The number of carbon atoms of the alkyl group of the alkyl (meth)acrylate (a) is 2 or more, preferably 4 or more, more preferably 4 to 20, still more preferably 6 to 18. By using the alkyl (meth)acrylate (a) having such an alkyl group, it is possible to form an adhesive layer in which a chemical liquid (for example, an acidic or alkaline chemical liquid) is hard to penetrate.

Specific examples of the (meth)acrylic monomer (b) having an OH group include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and 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), a carboxyl group such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxy amyl acrylate, itaconic acid, maleic acid, fumaric acid or crotonic acid can also be used. (Meth)acrylic monomer. The (meth)acrylic monomer (b) may be used singly or in combination of two or more.

The (meth)acrylic polymer contained in the acrylic pressure-sensitive adhesive I may contain a (meth)acrylic acid alkyl ester (a) as needed for the purpose of modifying the cohesive force, heat resistance, crosslinkability, and the like. And / or a structural unit corresponding to another monomer copolymerized with the (meth)acrylic monomer (b). Examples of such a monomer include methyl (meth)acrylate; anhydride monomers such as maleic anhydride and itaconic anhydride; styrenesulfonic acid, allylsulfonic acid, and 2-(methyl)acrylamide. a sulfonic acid group-containing monomer such as -2-methylpropanesulfonic acid, (meth)acrylamide, propanesulfonic acid, sulfopropyl (meth)acrylate or (meth)acryloxynaphthalenesulfonic acid; Methyl) acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N-hydroxyl (N-substituted) guanamine monomer such as methyl propane (meth) acrylamide; aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (A) (meth)Aminoalkyl (meth) acrylate monomer such as tert-butylaminoethyl acrylate; methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, etc. Alkoxyalkyl acrylate monomer; N-cyclohexylmaleimide, N-isopropylmaleimide, N-lauryl maleimide, N-phenyl Malay Maleimide monomer such as quinone imine; N-methyl Ikonium imine, N-ethyl Ikonide, N-butyl Ikonide, N- An ikonide imine monomer such as octyl carbamide, N-2-ethylhexyl ketimine, N-cyclohexyl ketimine, N-lauryl thioglycinide; N-(methyl) propylene oxime methylene succinimide, N-(methyl) propylene fluorenyl-6-oxyhexamethylene succinimide, N-(meth) acrylonitrile Amber quinone imine monomer such as 8-methoxy-octamethyl succinimide; vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine , vinyl piperidone, vinyl pyrimidine, vinyl pipe Vinylpyr , vinyl pyrrole, vinyl imidazole, vinyl Azole, vinyl Vinyl, N-vinylcarboamide, styrene, α -methylstyrene, N-vinyl caprolactam and other vinyl monomers; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile An epoxy group-containing acrylic monomer such as glycidyl (meth)acrylate; polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (methyl) a diol-based acrylate monomer such as acrylate or methoxypolypropylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, or polyoxymethylene (meth) acrylate An acrylate monomer having a hetero ring, a halogen atom, a ruthenium atom or the like; hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(a) 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 acrylic pressure-sensitive adhesive I is an alkyl (meth)acrylate (a) having an alkyl group having 2 or more carbon atoms by any appropriate polymerization method, and has an OH group. The (meth)acrylic monomer (b) and the other monomer (c) used as needed are obtained by polymerization. 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). The structural unit A of the alkyl acrylate and the structural unit B derived from the (meth)acrylic monomer having an OH group. In other words, the (meth)acrylic polymer includes a structural unit A having a side chain having an alkyl group having 2 or more carbon atoms, and a structural unit B having an OH group.

The content ratio of the (meth)acrylic polymer containing the structural unit A and the structural unit B is preferably 50 parts by weight to 100 parts by weight, more preferably 50 parts by weight to 100 parts by weight, based on 100 parts by weight of the solid content component in the acrylic pressure-sensitive adhesive I. 60 parts by weight to 98 parts by weight, more preferably 65 parts by weight 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 parts by weight to 98 parts by weight based on 100 parts by weight of the above (meth)acrylic polymer. The parts by weight are more preferably 80 parts by weight to 95 parts by weight, 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 from 1 part by weight to 30 parts by weight, more preferably from 100 parts by weight to the above (meth)acrylic polymer. 2 parts by weight to 20 parts by weight, more preferably 3 parts by weight to 10 parts by weight.

In the (meth)acrylic polymer included in the acrylic adhesive I, the molar ratio (C/OH) of the carbon (C) to the OH group of the side chain alkyl group is preferably from 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. Further, the above molar ratio (C/OH) may be a monomer which forms a structural unit having a side chain alkyl group (i.e., alkyl (meth)acrylate (a), and optionally used (meth)acrylic acid The amount of the ester, the molecular weight, the amount of the side chain alkyl group, 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, the monomer a ₁ , the monomer a ₂ and the monomer a _{3 are} used as a monomer for forming a structural unit having a side chain alkyl group, and the monomer b ₁ and the monomer b _{2 are} used as the (meth)acrylic acid. In the case of the monomer (b), the above molar ratio (C/OH) can be determined 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 amount of the monomer b ₂ (g)) / (the molecular weight of the monomer b ₂ )} (1)

In the present invention, by containing a specific amount of an alkyl group having 2 or more carbon atoms in the (meth)acrylic polymer as the base polymer, the polarity of the adhesive layer can be lowered to prevent the chemical liquid (for example, acidic or Infiltration of alkaline liquid). On the other hand, if the polarity of the adhesive layer is too low, sufficient adhesion cannot be obtained. However, in the present invention, the (meth)acrylic polymer further contains an OH group, and the side chain alkyl group is Carbon (C) and OH group When the ratio (C/OH) is in the above range, the adhesion can be maintained and the penetration of the chemical solution into the adhesive layer can be prevented. The heat-peelable pressure-sensitive adhesive sheet of the present invention having the above-mentioned pressure-sensitive adhesive layer capable of exhibiting excellent adhesion by containing a specific amount of OH groups can effectively prevent the intrusion of the chemical solution into the interface between the pressure-sensitive adhesive sheet and the adherend. When the penetration of the chemical solution is prevented, the deterioration of the adhesive can be suppressed, so that excellent adhesion can be maintained. Further, since the heat-expandable microspheres in the pressure-sensitive adhesive layer can be suppressed from being deteriorated by the chemical liquid, the thermal peelability is not impaired even when used in an acidic or alkaline chemical solution. Further, the adhesive composed of the (meth)acrylic polymer is less likely to inhibit swelling or foaming of the heat-expandable microspheres. The above-mentioned heat-peelable pressure-sensitive adhesive sheet which can achieve such effects can be preferably used as a protective sheet in the step of using an acidic or alkaline chemical liquid such as an etching treatment 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) is preferably 10 in terms of polystyrene. 10,000 to 3 million, more preferably 200,000 to 2.5 million, and even more preferably 300,000 to 2 million.

<additive>

The above acrylic adhesive I may contain any appropriate additives as needed. Examples of the additive include a crosslinking agent, an adhesion-imparting agent, and a plasticizer (for example, a trimellitate-based plasticizer or 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 a rosin-based adhesion-imparting resin (for example, unmodified rosin, modified rosin, rosin phenol-based resin, rosin ester-based resin, etc.) and a terpene-based adhesion-imparting resin (for example, ruthenium). An olefin resin, a terpene phenol resin, a styrene-modified terpene resin, an aromatic modified terpene resin, a hydrogenated terpene resin, and a hydrocarbon-based adhesion-imparting resin (for example, an aliphatic hydrocarbon resin, Aliphatic cyclic hydrocarbon resin, aromatic hydrocarbon resin (for example, styrene resin, xylene resin, etc.), aliphatic. Aromatic petroleum resin, aliphatic. An alicyclic petroleum resin, a hydrogenated hydrocarbon resin, a coumarone resin, a coumarone oxime resin, or the like, and a phenolic adhesion-imparting resin (for example, an alkylphenol resin, a xylene formaldehyde resin, a resol resin) A ketone-based adhesion-imparting resin, a polyamide-based adhesion-imparting resin, an epoxy-based adhesion-imparting resin, an elastic system adhesion-imparting resin, 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 preferable. The adhesion-imparting agents may be used singly or in combination of two or more.

Commercially available products can also be used as the above-mentioned adhesion-imparting agent. Specific examples of the adhesive-imparting agent of the commercial product include terpene phenol resin such as YS POLYSTAR S145, "Mighty Ace K140" manufactured by YASUHARA CHEMICAL Co., Ltd., and "TAMANOL 901" manufactured by Arakawa Chemical Co., Ltd. A rosin phenol resin such as "TAILOL RESIN PR-12603" manufactured by Sumitomo Bakelite and a product name "TAMANOL 361" manufactured by Arakawa Chemical Co., Ltd.; and alkane such as "TAMANOL 1010R" and "TAMANOL 200N" manufactured by Arakawa Chemical Co., Ltd. A phenol resin; an alicyclic saturated hydrocarbon resin such as "ARKON P-140" manufactured by Arakawa Chemical Co., Ltd., and the like.

The amount of the adhesion-imparting agent added 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, still more preferably 15 parts by weight to 25 parts by weight based on 100 parts by weight of the pressure-sensitive adhesive layer. Parts by weight. When it is such a range, it is possible to form an adhesive layer which is excellent in adhesion and unevenness followability. When the adhesive layer excellent in unevenness and followability is formed, it is possible to significantly prevent the chemical solution from intruding between the adhesive layer and the adherend.

The hydroxyl group of the above-mentioned adhesion-imparting agent is preferably 10 mgKOH/g or more, more preferably 40 mgKOH/g to 400 mgKOH/g. If it is such a range, the effect of this invention becomes remarkable, taking into consideration the adhesiveness and the prevention of penetration of a chemical solution.

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, and a metal alkoxide crosslinking. A crosslinking agent, a metal chelate crosslinking agent, a metal salt crosslinking agent, a carbodiimide crosslinking agent, An oxazoline crosslinking agent, an aziridine crosslinking agent, an amine crosslinking agent, and the like. Among them, an isocyanate crosslinking agent or an epoxy crosslinking agent is preferred.

Specific examples of the above isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butyl diisocyanate and hexamethylene diisocyanate; cyclopentyl diisocyanate, cyclohexyl diisocyanate, and isophor An alicyclic isocyanate such as keto diisocyanate; an aromatic isocyanate such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate or benzodimethyl diisocyanate; trimethylolpropane/toluene 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"), an isocyanate product such as an isocyanurate body of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry, trade name "CORONATE HX"). The content of the isocyanate crosslinking agent can be set to any appropriate amount depending on the desired adhesive strength, and is 100 parts by weight based on 100 parts by weight of the base polymer (that is, (meth)acrylic polymer) in the acrylic pressure-sensitive adhesive I. Typically, it is from 0.1 part by weight to 20 parts by weight, more preferably from 0.5 part by weight to 10 parts by weight.

Examples of the epoxy-based crosslinking agent include N,N,N',N'-tetraglycidyl meta-xylylenediamine, diglycidylaniline, and 1,3-bis(N,N-shrinkage). Glycerylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name "TETRAD C"), 1,6-hexanediol diglycidyl ether (manufactured by Kyoeisha Chemical Co., Ltd., 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 & Fats Co., Ltd., trade name "EPIOL E-400"), polypropylene glycol diglycidyl ether (made by Japan Oil Company) Manufactured under the trade name "EPIOL P-200"), sorbitol polyglycidyl ether (manufactured by Nagase ChemteX, trade name "Denacol EX-611"), glycerol polyglycidyl ether (manufactured by Nagase ChemteX, trade name "Denacol" EX-314"), pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX, trade name "Denacol EX-512"), sorbitan polyglycidyl ether, trimethylolpropane polycondensate Glycerol ether, diglycidyl adipate, diglycidyl phthalate, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol S- A diglycidyl ether or an epoxy resin having two or more epoxy groups in its molecule. The content of the epoxy-based crosslinking agent can be set to any appropriate amount depending on the desired adhesive force, and is typically 0.01 parts by weight to 10 parts by weight, more preferably 0.03 parts by weight, per 100 parts by weight of the base polymer. ~5 parts by weight.

B-2. Heat-expandable microspheres

The heat-expandable microspheres refer to microspheres which can be expanded or foamed by heating. The heat-peelable pressure-sensitive adhesive sheet having the adhesive layer containing the heat-expandable microspheres has irregularities on the bonding surface by heating, and the adhesive force is lowered, so that it has sufficient adhesive force in the case where adhesive force is required, and is required It is excellent in peeling property in the case of peeling. As described above, in the present invention, even when exposed to an acidic or alkaline chemical liquid, the heat-expandable microspheres are not easily deteriorated, and the above functions as heat-expandable microspheres can be sufficiently exhibited.

The content ratio of the above-mentioned heat-expandable microspheres can be appropriately set depending on the desired reduction in adhesion or the like. The content ratio of the heat-expandable microspheres is, for example, 1 part by weight to 150 parts by weight, preferably 10 parts by weight to 130 parts by weight, per 100 parts by weight of the (meth)acrylic polymer in the acrylic pressure-sensitive adhesive I. Further, it is preferably 25 parts by weight to 100 parts by weight.

As the heat-expandable microspheres, any suitable heat-expandable microspheres can be used. As the heat-expandable microspheres, for example, microspheres obtained by allowing a substance which is easily expanded by heating to be contained in an elastic shell can be used. Such heat-expandable microspheres can be used arbitrarily The method is produced, for example, by a coacervation method, an interfacial polymerization method, or the like.

Examples of the substance which is easily swelled by heating include propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, heptane, a low boiling point liquid such as octane, petroleum ether, methane halide or tetraalkyl decane; azodicarbonamide vaporized by thermal decomposition.

Examples of the material constituting the shell include a polymer composed of acrylonitrile, methacrylonitrile, α -chloroacrylonitrile, α -ethoxy acrylonitrile, and fumaronitrile. (fumaronitrile) and other nitrile monomers; carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid; vinylidene chloride; vinyl acetate; Ester, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, (meth)acrylic acid Ester, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, β -carboxyethyl acrylate (meth) acrylate; styrene, styrene, α -methyl styrene, chlorostyrene, etc. a phthalamide monomer such as acrylamide, substituted acrylamide, methacrylamide or substituted methacrylamide. The polymer composed of the monomers may be a homopolymer or a copolymer. The copolymer may, for example, be a vinylidene chloride-methyl methacrylate-acrylonitrile copolymer, a methyl methacrylate-acrylonitrile-methacrylonitrile copolymer, or a methyl methacrylate-acrylonitrile copolymer. , acrylonitrile-methacrylonitrile-iconic acid copolymer, and the like.

As the heat-expandable microspheres, an inorganic foaming agent or an organic foaming agent can also be used. Examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogencarbonate, sodium hydrogencarbonate, ammonium nitrite, sodium borohydride, various azide compounds, and the like. Further, examples of the organic foaming agent include chlorofluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile, azodimethylamine, and azodicarboxylate; An azo compound such as strontium sulphate; p-toluene sulfonium, diphenyl hydrazine-3,3'-disulfonium sulfonate, 4,4'-oxybis(phenylsulfonate), allyl bis (sulfonate)醯肼) an oxime compound; an aminourea-based compound such as p-toluenesulfonylamino urea or 4,4'-oxybis(phenylsulfonylamino urea); Triazole compound such as phenyl-1,2,3,4-thiatriazole; N,N'-dinitrosopentamethylenetetramine, N,N'-dimethyl-N,N'- An N-nitroso compound such as dinitroso-p-xylyleneamine or the like.

A commercially available product can also be used for the above-mentioned heat-expandable microspheres. Specific examples of the heat-expandable microspheres of the commercially available product include the product name "Matsumoto Microsphere" manufactured by Matsumoto Oil & Fat Pharmaceutical Co., Ltd. (Grade: F-30, F-30D, F-36D, F-36LV, F-50) , F-50D, F-65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), the product name manufactured by Japan Fillite Co., Ltd. Expancel" (grade: 053-40, 031-40, 920-40, 909-80, 930-120), "DAIFOAM" manufactured by Wu Yu Chemical Industry Co., Ltd. (Class: H750, H850, H1100, S2320D, S2640D, M330) , M430, M520), "ADVANCELL" manufactured by Sekisui Chemical Industry Co., Ltd. (grade: EML101, EMH204, EHM301, EHM302, EHM303, EM304, EHM401, EM403, EM501).

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

The heat-expandable microspheres preferably have an appropriate strength until the volume expansion ratio is preferably 5 times or more, more preferably 7 times or more, still more preferably 10 times or more. When such a heat-expandable microsphere is used, the adhesion can be efficiently reduced by heat treatment.

B-3. Characteristics of the first adhesive layer, etc.

The thickness of the first adhesive layer is preferably from 1 μm to 100 μm, more preferably from 5 μm to 80 μm, still more preferably from 10 μm to 50 μm. As described above, the first adhesive layer contains a layer of heat-expandable microspheres. Therefore, the thickness of the first adhesive layer refers to the outer surface (the side opposite to the substrate) from the outer side of the first adhesive layer when the thickness direction cross section of the first adhesive layer is observed. The distance from the innermost end of the thermally expandable microsphere of the substrate.

The difference (thickness-average particle diameter) of the thickness of the first adhesive layer and the average particle diameter of the heat-expandable microspheres contained in the first adhesive layer is preferably 8 μm or more, more preferably 10 μm or more, and further preferably It is 15 μm or more, particularly preferably 20 μm or more, and most preferably 25 μm to 100 μm. If it is such a range, it is possible to obtain a heat-peelable pressure-sensitive adhesive sheet in which the first adhesive layer has an appropriate surface roughness and the chemical liquid is hard to penetrate into the interface between the first adhesive layer and the adherend.

The elastic modulus of the first adhesive layer measured by a nanoindentation method at 25 ° C is preferably 0.01 MPa to 50 MPa, more preferably 0.1 MPa to 10 MPa, and particularly preferably 0.5 MPa to 5 MPa. When the elastic modulus of the pressure-sensitive adhesive layer is in the above range, a heat-peelable pressure-sensitive adhesive sheet excellent in adhesion, cutting property, and step followability can be obtained. The elastic modulus measured by the nanoindentation method refers to continuously measuring the load load and the indentation depth of the indenter when the indenter is pressed into the sample during the loading and unloading, and the resulting load is loaded. The modulus of elasticity obtained by pressing in the depth curve. In this specification, the elastic modulus measured by the nanoindentation method means that the measurement conditions are set as the load: 1 mN, load. Unloading speed: 0.1 mN/s, holding time: 1 s, and the elastic modulus obtained by measurement 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 or the like. Further, an additive may be added to the first adhesive layer to adjust the elastic modulus. For example, if the first adhesive layer contains beads, the elastic modulus of the adhesive layer can be increased. Examples of the beads include glass beads, resin beads, and the like. The average particle diameter of the beads is, for example, 0.01 μm to 50 μm. The amount of the beads added is, for example, 10 parts by weight to 200 parts by weight, preferably 20 parts by weight to 100 parts by weight, based on 100 parts by weight of the total of the pressure-sensitive adhesive layer.

The center line 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, still more preferably 0.06 μm to 0.6 μm. . If it is in this range, it is possible to obtain a chemical solution that is difficult to penetrate into the first A heat-peelable adhesive sheet at the interface between the adhesive layer and the 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 from 85 to 115, more preferably from 87 to 115, still more preferably from 90 to 115. When the contact angle of water is more 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 chemical 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%, still more preferably 55% to 99%. If it is such a range, it can prevent that a chemical solution invades into an 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 described above contains any suitable adhesive. As the adhesive contained in the second adhesive layer, in terms of adhesion, when the second adhesive layer contains the thermally expandable microspheres, the expansion or the expansion of the heat-expandable microspheres is not restricted when heated. Examples of the foam include an acrylic adhesive, a rubber adhesive, a vinyl alkyl ether adhesive, a polyoxygen adhesive, a polyester adhesive, a polyamide adhesive, and an amine. A urethane-based adhesive, a styrene-diene block copolymer-based adhesive, an active energy ray-curable adhesive, and the like. Further, the above-mentioned adhesive may be a creep-modified adhesive having a hot-melt resin having a melting point of about 200 ° C or less. The details of the creep property improving adhesive are described in Japanese Laid-Open Patent Publication No. SHO 56-61468, Japanese Patent Application Laid-Open No. SHO63-17981, and the like. Among the above adhesives, an acrylic adhesive or a rubber adhesive can be preferably used. Further, the above-mentioned adhesives may be used singly or in combination of two or more.

As the acrylic adhesive contained in the second adhesive layer, any appropriate acrylic adhesive can be used. For example, an acrylic-based adhesive which uses an acrylic polymer (homopolymer or copolymer) having one or two or more kinds of alkyl (meth)acrylates as a monomer component as a base polymer, and the like can be mentioned. In one embodiment, the acrylic adhesive I described in the above item B can be used.

Examples of the rubber-based pressure-sensitive adhesive include a rubber-based adhesive having a rubber as a base polymer: 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-butylene-styrene block copolymer (SEBS) rubber, styrene-ethylene-propylene-styrene block copolymer (SEPS) rubber, styrene-ethylene-propylene block copolymer (SEP) rubber, regeneration A synthetic rubber such as rubber, butyl rubber, polyisobutylene, or a modified body thereof.

As the adhesive contained in the second adhesive layer, an active energy ray-curable adhesive which can be cured (high elastic modulus) by irradiation with an active energy ray can also be used. When an active energy ray-curing type adhesive is used, the following heat-peelable pressure-sensitive adhesive sheet can be obtained, which is low in elasticity at the time of attachment, high in flexibility, and excellent in handleability, and is irradiated with active energy rays when peeling is required. Can reduce adhesion. Examples of the active energy rays include gamma rays, ultraviolet rays, visible rays, infrared rays (heat rays), radio frequency waves, α rays, β rays, electron beams, plasma streams, ionizing rays, particle beams, and the like.

Examples of the resin material constituting the active energy ray-curable adhesive include an ultraviolet curing system (Approved by Kato Qingyu, Integrated Technology Center, (1989)), photo-curing technology (Technical Information Association (2000)), and Japan. A resin material described in JP-A-2003-292916, Japanese Patent No. 4151850, and the like. More specifically, a resin containing a polymer as a mother agent and an active energy ray-reactive compound (monomer or oligomer) may be mentioned. Material (R1), resin material (R2) containing active energy ray-reactive polymer, and the like.

Examples of the polymer to be used as the mother agent include natural rubber, polyisobutylene rubber, styrene-butadiene rubber, styrene-isoprene-styrene block copolymer rubber, recycled rubber, and butyl rubber. A rubber-based polymer such as polyisobutylene rubber or nitrile rubber (NBR); a polyfluorene-based polymer; an acrylic polymer. These polymers may be used singly or in combination of two or more.

The active energy ray-reactive compound may, for example, be a photoreactive monomer having a functional group having a carbon-carbon multiple bond such as an acrylonitrile group, a methacryl group, a vinyl group, an allyl group or an ethynyl group, or a low Polymer. Specific examples of the photoreactive monomer or oligomer include trimethylolpropane tri(meth)acrylate, tetramethylolmethanetetra(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 a (meth)acrylonitrile-containing compound such as 6-hexanediol di(meth)acrylate or polyethylene glycol di(meth)acrylate; and the (meth)acrylonitrile-containing compound 2 ~5 polymer and so on.

Further, as the active energy ray-reactive compound, a monomer such as epoxidized butadiene, glycidyl methacrylate, acrylamide or vinyl oxirane; or oligomerization composed of the monomer may be used. Things. The resin material (R1) containing these compounds can be hardened by a high-energy line such as an ultraviolet ray or an electron beam.

Further, as the active energy ray-reactive compound, a mixture of an organic salt such as a phosphonium salt and a compound having a plurality of heterocyclic rings in the molecule may be used. The mixture is cleaved by irradiation of an active energy ray (e.g., ultraviolet ray, electron beam) to form an ion which becomes an initial species to cause a ring opening reaction of the hetero ring, thereby enabling formation of a three-dimensional network structure. Examples of the organic salt include a phosphonium salt, a phosphonium salt, a phosphonium salt, a phosphonium salt, and a borate. Examples of the heterocyclic ring in the compound having a plurality of heterocyclic rings in the molecule include oxirane, oxetane, oxolane, ethylene sulfide, and aziridine.

Further, as the active energy ray-reactive compound, a mixture of an organic salt such as a phosphonium salt and a compound having a plurality of heterocyclic rings in the molecule may be used. The mixture is cleaved by irradiation of an active energy ray (e.g., ultraviolet ray, electron beam) to form an ion which becomes an initial species to cause a ring opening reaction of the hetero ring, thereby enabling formation of a three-dimensional network structure. Examples of the organic salt include a phosphonium salt, a phosphonium salt, a phosphonium salt, a phosphonium salt, and a borate. Examples of the heterocyclic ring in the compound having a plurality of heterocyclic rings in the molecule include oxirane, oxetane, oxolane, ethylene sulfide, and aziridine.

In the resin material (R1) containing the polymer 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 based on 100 parts by weight of the polymer to be the mother agent. It is preferably 500 parts by weight, more preferably 1 part by weight to 300 parts by weight, still more preferably 10 parts by weight to 200 parts by weight.

The resin material (R1) containing the polymer to be a mother agent and the active energy ray-reactive compound may optionally contain any appropriate additives. Examples of the additive include an active energy ray polymerization initiator, an active energy ray polymerization accelerator, a crosslinking agent, a plasticizer, a vulcanizing agent, and the like. As the active energy ray polymerization initiator, any appropriate initiator can be used depending on the kind of active energy ray used. The active energy ray polymerization initiators may be used singly or in combination of two or more. In the resin material (R1) containing the polymer 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 based on 100 parts by weight of the polymer to be the mother agent. It is preferably 10 parts by weight, more preferably 1 part by weight to 5 parts by weight.

The active energy ray-reactive polymer may, for example, be a polymer having a functional group having a carbon-carbon multiple bond such as an acrylonitrile group, a methacryl group, a vinyl group, an allyl group or an ethynyl group. Specific examples of the polymer having an active energy ray-reactive functional group include a polymer composed of a polyfunctional (meth) acrylate, a photocationic polymerizable polymer, and a polycinnamate-containing vinyl ester containing a cinnamyl group. Polymer; diazotized amino novolak resin; polypropylene decylamine and the like. Active energy ray reactive poly As the resin material (R2), 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 curing by irradiation with an active energy ray (for example, when a heat-peelable adhesive sheet is attached), in addition to having an active energy ray reaction In addition to the functional group-based polymer, an oligomer having an active energy ray-reactive functional group can also be used.

The resin material (R2) containing the active energy ray-reactive polymer may further contain the above active energy ray-reactive compound (monomer or oligomer). Further, the resin material (R2) containing the active energy ray-reactive polymer may contain any appropriate additives as needed. Specific examples of the additive are the same as those which may be contained in the resin material (R1) containing the polymer to be 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 from 0.1 part by weight to 10 parts by weight per 100 parts by weight of the active energy ray-reactive polymer. More preferably, it is 1 part by weight - 5 parts by weight.

The adhesive contained in the above second adhesive layer may contain any appropriate additive as needed. Examples of the additive to be used include the additives described in the above item B-1. Further, the addition amount of the additive (adhesion-imparting agent, crosslinking agent, etc.) is also preferably the addition amount described in the item B-1. Therefore, in one embodiment, the second adhesive layer may include an adhesion-imparting agent, and the content of the adhesion-imparting agent is preferably 40 parts by weight or less, more preferably 30 parts by weight or less based on 100 parts by weight of the adhesive layer. Further, it is preferably 25 parts by weight or less, more preferably 3 parts by weight to 25 parts by weight.

C-2. Heat-expandable microspheres

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

C-3. Characteristics of the second adhesive layer, etc.

The thickness of the second adhesive layer is preferably from 1 μm to 100 μm, more preferably from 5 μm to 80 μm, still more preferably from 10 μm to 50 μm. In the case where the second adhesive layer contains the heat-expandable microspheres, the thickness of the second adhesive layer is set to be the same as the thickness of the first adhesive layer: when the thickness direction cross section of the second adhesive layer is observed The distance from the outer side of the second adhesive layer (the side opposite to the substrate) to the innermost end of the thermally expandable microsphere closest to the substrate.

When the second adhesive layer contains the heat-expandable microspheres, the difference between the thickness of the second adhesive layer and the average particle diameter of the heat-expandable microspheres contained in the second adhesive layer (thickness-average particle diameter) It is preferably 8 μm or more, more preferably 10 μm or more, further 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 a nanoindentation method at 25 ° C is preferably 0.01 MPa to 50 MPa, more preferably 0.1 MPa to 10 MPa, and particularly preferably 0.5 MPa to 5 MPa.

The center line 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, still more preferably 0.06 μm to 0.6 μm. .

The contact angle of water with respect to the second adhesive layer is preferably from 85 to 115, more preferably from 87 to 115, still more preferably from 90 to 115.

The gel fraction of the second adhesive layer is preferably 50% or more, more preferably 52% to 99%, still more preferably 55% to 99%. If it is such a range, it can prevent that a chemical solution invades into an adhesive layer.

D. Substrate

Examples of the substrate include a resin sheet, a nonwoven fabric, paper, a metal foil, a woven fabric, a rubber sheet, and a foamed sheet. Further, a substrate composed of the laminate (especially a laminate including a resin sheet) or a plurality of materials as a raw material may be used. Combined with the 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), polyamine (nylon), wholly aromatic polyamine (aromatic polyamide), polyimine (PI), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluororesin, polyetheretherketone (PEEK), urethane acrylate, acrylic resin (preferably UV-curable acrylic) Resin) and the like. Among them, PET, PEN, PE or PP can be preferably used from the viewpoint of acid resistance. Examples of the nonwoven fabric include non-woven fabrics made of natural fibers having heat resistance such as non-woven fabrics of Manila hemp; synthetic resin nonwoven fabrics such as polypropylene resin nonwoven fabrics, polyethylene resin nonwoven fabrics, and ester resin nonwoven fabrics.

The elastic modulus of the substrate measured by a nanoindentation method at 25 ° C is preferably 10 MPa to 10 GPa. The elastic modulus of the substrate measured by a nanoindentation method at 25 ° C is preferably 100 MPa to 5 GPa, and more preferably 500 MPa to 5 GPa. When it is such a range, it is possible to obtain a heat-peelable pressure-sensitive adhesive sheet which is excellent in cutting property and in the case of bonding.

The thickness of the substrate is preferably from 1 μm to 1000 μm, more preferably from 2 μm to 250 μm, still more preferably from 10 μm to 100 μm. When it is such a range, it is possible to obtain a heat-peelable pressure-sensitive adhesive sheet which is excellent in cutting property and in the case of bonding.

The substrate may also 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. When 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, the coating treatment by the organic coating material is preferable because it can suppress the cracking of the adhesive layer at the time of heat peeling.

Examples of the organic coating material include materials described in Plastic Hard Coating Material II (CMC Publishing, (2004)). It is preferred to use a urethane-based polymer, more preferably a polyacrylic acid urethane, a polyester urethane or the precursor. The reason is The coating on the substrate is simple and industrially selectable and can be obtained at low cost. The urethane-based polymer is, for example, a polymer comprising a reaction mixture of an isocyanate monomer and an alcoholic hydroxyl group-containing monomer (for example, a hydroxyl group-containing acrylic compound or a hydroxyl group-containing ester compound). The organic coating material may also contain a chain extender such as a polyamine, an anti-aging agent, an oxidation stabilizer or the like as an optional additive. The thickness of the organic coating layer is not particularly limited, and is, for example, 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 manufactured by Arakawa Chemical Industries Co., Ltd. (for example, a combination of the trade name "AP2500E" and the trade name "CL2500" as a curing agent) and the product name "NB300" manufactured by Daisei Seiki Co., Ltd. can be used. A commercial item such as the product name "HR Color".

E. Elastic layer

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

The above elastic layer contains a base polymer, and as the base polymer, an adhesive polymer can be used. Examples of the base polymer constituting the elastic layer include a (meth)acrylic polymer; a rubber-based polymer such as a natural rubber or a synthetic rubber (for example, a nitrile-based, a diene-based or an acrylic-based); a polyolefin-based polymer; Thermoplastic elastomer such as ester; vinyl alkyl ether polymer; polyoxynene polymer; polyester polymer; polyamine polymer; urethane polymer; styrene-diene Block copolymer; ethylene-vinyl acetate copolymer; polyurethane polymer; polybutadiene; soft polyvinyl chloride; radiation hardening polymer. The base polymer constituting the elastic layer may be the same as or different from the base polymer forming the pressure-sensitive adhesive layer (the first adhesive layer and/or the second adhesive layer). The elastic layer may also be a foamed film formed of the above base polymer. The foamed film can be obtained by any suitable method. Further, the elastic layer and the first adhesive layer (and the second adhesive layer containing the heat-expandable microspheres) can be distinguished by the presence or absence of heat-expandable microspheres (the elastic layer does not contain heat-expandable microspheres).

The (meth)acrylic polymer as a base polymer constituting the elastic layer is, for example, An acrylic polymer (homopolymer or copolymer) having one or two or more kinds of alkyl (meth)acrylates as a monomer component. 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. Further, the acrylic polymer may further comprise a unit corresponding to another monomer component copolymerizable with the alkyl (meth)acrylate. Examples of such a monomer component include acrylic acid, methacrylic acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and N-methylol group. Acrylamide, acrylonitrile, methacrylonitrile, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, styrene, isoprene, butadiene, isobutylene, vinyl ether, and the like.

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

The thickness of the elastic layer is preferably from 3 μm to 200 μm, more preferably from 5 μm to 100 μm. If it is such a range, the above-mentioned function of an elastic layer can fully exhibit.

The tensile modulus of the elastic layer at 25 ° C is preferably less than 100 MPa, more preferably 0.1 MPa to 50 MPa, still more preferably 0.1 MPa to 10 MPa. If it is such a range, the above-mentioned function of an elastic layer can fully exhibit.

F. Method for manufacturing thermal peeling adhesive sheet

The heat-peelable adhesive sheet of the present invention can be produced by any appropriate method. The heat-peelable pressure-sensitive adhesive sheet of the present invention may, for example, be a method in which a first adhesive layer-forming composition is directly applied to one surface of a substrate, and a second adhesive is applied to the other surface of the substrate. A method of forming a composition for layer formation; a method of transferring a coating layer formed by coating on any appropriate substrate to a substrate, forming a first adhesive layer and a second adhesive layer, and the like. Further, the adhesive layer containing the heat-expandable microspheres can also utilize a combination comprising an adhesive After forming the adhesive coating layer, the heat-expandable microspheres are sprinkled on the adhesive coating layer, and then formed by embedding the heat-expandable microspheres into the coating layer using a laminator or the like.

The first adhesive layer-forming composition contains the acrylic pressure-sensitive adhesive I and the heat-expandable microspheres, and optionally contains any appropriate solvent. The second adhesive layer-forming composition contains any appropriate adhesive, and if necessary, contains the above-mentioned heat-expandable microspheres and/or any appropriate solvent.

In the case where the heat-peelable adhesive sheet has the elastic layer, the elastic layer and the adhesive layer adjacent to the elastic layer may be coated with a composition for forming an elastic layer, for example, and then coated with an adhesive layer. Formed from the composition. For example, a composition for forming an elastic layer containing a material (base polymer, an additive, etc.) forming an elastic layer is applied onto a substrate, and then a coating composition for forming the first adhesive is applied onto the coating layer of the composition for forming an elastic layer. Thereby, the elastic layer and the first adhesive layer can be sequentially formed from the substrate side.

As the coating method of each of the above compositions, any appropriate coating method can be employed. For example, it can be dried after coating to form each layer. Examples of the coating method include a coating method using, for example, a multi-coater, a die coater, a gravure coater, and an applicator. Examples of the drying method include natural drying, heat drying, and the like. The heating temperature in the case of heating and drying can be set to any appropriate temperature depending on the characteristics of the substance to be dried.

G. Use

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

The heat-peelable adhesive sheet of the present invention is a double-sided adhesive sheet, which can prevent the warpage of the electronic component by bonding the two sides of the adhesive sheet to the electronic component of the processed object and supplying the electronic component to the processing step. . Further, by performing the processing steps in the above manner, it is possible to improve the production efficiency.

[Examples]

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

[Manufacturing Example 1] Preparation of Acrylic Adhesive I(i)

(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) 100 parts by weight And an epoxy-based crosslinking agent (trade name "TETRAD C", manufactured by Mitsubishi Gas Chemical Co., Ltd.), 0.6 parts by weight, and a terpene-based adhesion-imparting resin (manufactured by YASUHARA CHEMICAL Co., Ltd., trade name "YS POLYSTAR T130"), 30 parts by weight. The mixing was carried out to prepare an acrylic adhesive I(i).

[Production Examples 2 to 9] Preparation of Acrylic Adhesive I(ii) to (ix)

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

TETRAD X: epoxy crosslinker; manufactured by Mitsubishi Gas Chemical Co., Ltd. under the trade name "TETRAD X"

CORONATE L: isocyanate crosslinking agent; manufactured by Nippon Polyurethane Industry, trade name "CORONATE L"

SUPER ESTER A-75: rosin-based adhesive resin; manufactured by Arakawa Chemical Industries, Inc., under the trade name "SUPER ESTER A-75"

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

[Example 1]

130.6 parts by weight of the acrylic pressure-sensitive adhesive I (i) obtained in Production Example 1 and 25 parts by weight of heat-expandable microspheres (product name "Matsumoto Microsphere F-50D" manufactured by Matsumoto Oil & Fats Co., Ltd.) and 210 parts by weight of toluene were used. Mixing to prepare an adhesive layer Forming composition (i).

The adhesive layer-forming composition (i) was applied to both sides of a PET film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 100 μm) as a substrate to form a first adhesive layer having a thickness of 40 μm. And a second adhesive layer.

By the above operation, 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.

[Embodiment 2]

130.6 parts by weight of the acrylic pressure-sensitive adhesive I (i) obtained in Production Example 1, 30 parts by weight of heat-expandable microspheres (manufactured by Matsumoto Oil & Fats Co., Ltd., trade name "Matsumoto Microsphere F-48D"), and 210 parts by weight of toluene were used. The mixture was mixed to prepare a composition (ii) for forming an adhesive layer.

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

The elastic layer-forming composition (i) and the adhesive layer-forming composition (ii) were sequentially coated on one surface of a polyester film (manufactured by Mitsubishi Plastics, Inc., trade name "DIAFOIL", thickness: 50 μm) as a substrate. ), thereby forming an elastic layer (thickness: 20 μm) and a first adhesive layer (thickness: 40 μm). Further, the elastic layer forming composition (ii) and the adhesive layer forming composition (ii) are sequentially applied to the other surface of the substrate to form an elastic layer (thickness: 20 μm) and a second adhesive layer. (20 μm).

By the above operation, a thermal 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) was obtained in this order. sheet.

[Example 3]

151 parts by weight of the acrylic adhesive (iii) obtained in Production Example 3, and thermal expansion property 40 parts by weight of a ball (manufactured by Matsumoto Oil & Fats Pharmaceutical Co., Ltd., "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 for forming an elastic layer (iii), a mixture of 101 parts by weight of the acrylic pressure-sensitive adhesive I (iv) obtained in Production Example 4 and 210 parts by weight of toluene was prepared.

The elastic layer-forming composition (iii) and the adhesive layer-forming composition (iii) were sequentially coated on one surface of a PET film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 100 μm) as a substrate. ), thereby forming an elastic layer (thickness: 30 μm) and a first adhesive layer (thickness: 30 μm). Further, the elastic layer-forming composition (iii) and the adhesive layer-forming composition (iii) are 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).

By the above operation, a thermal 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) was obtained in this order. sheet.

[Example 4]

122 parts by weight of the acrylic pressure-sensitive adhesive (v) obtained in Production Example 5, 30 parts by weight of heat-expandable microspheres (manufactured by Japan Fillite Co., Ltd., trade name "Expancel 909-DU80"), and 210 parts by weight of toluene were mixed. 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 pressure-sensitive adhesive I (vi) obtained in Production Example 6 and 210 parts by weight of toluene was prepared.

The elastic layer-forming composition (iv) and the adhesive layer-forming composition (iv) were sequentially coated on one surface of a PET film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 50 μm) as a substrate. ), thereby forming an elastic layer (thickness: 25 μm) and a first adhesive layer (thickness: 50 μm). Further, the elastic layer forming composition (iv) and the adhesive layer forming composition (iv) are sequentially applied to the other surface of the substrate to form an elastic layer (thickness: 20 μm) and a second adhesive layer. (thickness: 30 μm).

By the above operation, a thermal 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) was obtained in this order. sheet.

[Comparative Example 1]

140.7 parts by weight of the acrylic pressure-sensitive adhesive I (vii) obtained in the production example 7 and 25 parts by weight of heat-expandable microspheres (manufactured by Matsumoto Oil & Fats Co., Ltd., trade name "Matsumoto Microsphere F-50D") and 210 parts by weight of toluene were used. The mixture was mixed to prepare a composition (v) for forming an adhesive layer.

The adhesive layer-forming composition (v) was applied to both sides of a PET film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 100 μm) as a substrate to form a first adhesive having a thickness of 45 μm. Layer and second adhesive layer.

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

[Comparative Example 2]

127 parts by weight of the acrylic pressure-sensitive adhesive I (viii) obtained in Production Example 8, 30 parts by weight of heat-expandable microspheres (manufactured by Japan Fillite Co., Ltd., 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 for forming an elastic layer (vi), a mixture of 117 parts by weight of the acrylic pressure-sensitive adhesive I (ix) obtained in Production Example 9 and 210 parts by weight of toluene was prepared.

The elastic layer-forming composition (vi) and the adhesive layer-forming composition (vi) were sequentially coated on one surface of a PET film (manufactured by Toray Industries, Inc., trade name "Lumirror S10", thickness: 100 μm) as a substrate. ), thereby forming an elastic layer (thickness: 20 μm) and a first adhesive layer (thickness: 40 μm). Further, an adhesive layer was formed on the other surface of the substrate to form a composition (vi), thereby forming a second adhesive layer (40 μm).

By the above operation, the first adhesive layer (40 μm) and the elastic layer (20) are sequentially obtained. Thermal exfoliation adhesive sheet of μm), substrate (100 μm), and second adhesive layer (40 μm).

[Evaluation]

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

(1) Center line 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 Co., Ltd., trade name "Wyko NT9100") was used, and measurement conditions were set as follows. The average value of the measured values obtained by measuring the vertical and horizontal directions five times is shown in Table 2.

(evaluation conditions)

Sample size: 50mm × 50mm

Measuring range: 2.534mm × 1.901mm

Measurement mode: VSL

Objective lens: 2.5 times

Internal lens: 1.0 times

(2) Contact angle

Using a contact angle meter (manufactured by Kyowa Interface Co., Ltd., trade name "CX-A type"), 2 μl of pure water was added to the surface of the first adhesive layer in an environment of 23 ° C / 50% RH, and dropped 5 The contact angle of the droplets was measured after two 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 the sample for evaluation sampled from the first resin layer was wrapped with a mesh sheet, and allowed to stand in 50 ml of toluene at room temperature for 1 week, and toluene was impregnated into the sample. Thereafter, the toluene-insoluble matter was taken out, dried at 70 ° C for 2 hours, and the dried toluene-insoluble matter was weighed.

Using the following formula, the weight of the sample before impregnating toluene and the weight of the toluene-insoluble component are calculated. The gel fraction of the resin layer.

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

(4) Method for measuring adhesion

The heat-peelable adhesive sheet was cut into a width of 20 mm and a length of 140 mm, based on JIS Z 0237 (2000), at a temperature of 23 ± 2 ° C and a humidity of 65 ± 5% RH, 2 kg The roll was reciprocated once, and the polyethylene terephthalate film (trade name "Lumirror S-10", manufactured by Toray Industries; thickness: 25 μm, width: 20 mm) as an adherend was pressure-bonded and attached to the first On an adhesive layer. Then, the heat-peelable adhesive sheet with the adherend was placed in a tensile tester (manufactured 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 the peeling angle: 180° and the peeling speed (tensile speed): 300 mm/min was measured at a temperature of 23° C., and the load was peeled off from the heat-peelable adhesive sheet, and the weight was determined. The maximum load (except for the maximum load of the peak at the beginning of the measurement) is used as the adhesion of the first adhesive layer (N/20 mm).

(5) Evaluation of drug invasion

The heat-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 at a temperature of 60 ° C and a pressure of 0.5. Under the conditions of MPa and time of 3 minutes, the samples for evaluation were prepared by pressure bonding. 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 the immersion, the amount of penetration of the chemical solution on the side of the first adhesive layer was evaluated based on the liquid intrusion distance from the end portion of the adhesive sheet.

(6) Heat stripping

A sample for evaluation was produced in the same manner as in the above (5) evaluation of drug solution intrusion. The sample for evaluation was heated at 130 ° C for 1 minute. The peeling condition of the wafer after heating was visually confirmed. In Table 2, the case where the adhesive layer loses the adhesive force and the wafer is peeled off is denoted as ○, and will adhere. The case where the agent layer has an adhesive force and the wafer is not peeled off is denoted as ×.

[Industrial availability]

The heat-peelable adhesive sheet of the present invention can be preferably used as a protective tape for electronic parts to be supplied to a treatment liquid such as an etching liquid.

10‧‧‧First adhesive layer

20‧‧‧Substrate

30‧‧‧Second Adhesive Layer

100‧‧‧Hot peeling adhesive sheet

Claims (9)

A heat-peelable adhesive sheet comprising a first adhesive layer, a substrate, and a second adhesive layer in sequence, the first adhesive layer containing an acrylic adhesive containing a (meth)acrylic polymer and thermal expansion Microspheres, the (meth)acrylic polymer comprising structural units derived from an alkyl (meth)acrylate having an alkyl group having 2 or more carbon atoms, and (meth)acrylic acid derived from an OH group A structural unit of a monomer in which a molar ratio (C/OH) of a carbon (C) to a OH group of a side chain alkyl group is 40 to 150. The heat-peelable adhesive sheet of claim 1, wherein the second adhesive layer comprises the above-mentioned heat-expandable microspheres. The heat-peelable adhesive sheet according to 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. The heat-peelable 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 adhesive sheet according to claim 1, wherein the first adhesive layer contains an adhesion-imparting agent, and the content of the adhesive-imparting agent is 40 parts by weight or less based on 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 contains an adhesion-imparting agent, and the content of the adhesion-imparting agent is 40 parts by weight or less based on 100 parts by weight of the second adhesive layer. The heat-peelable adhesive sheet of claim 1, wherein the first adhesive layer and/or the second adhesive layer has a gel fraction of 50% or more. The heat-peelable adhesive sheet of claim 1, wherein the first adhesive layer is attached to the side When the polyethylene terephthalate film is used, the adhesion at 23 ° C is 1 N / 20 mm or more. An electronic component manufactured using the heat-peelable adhesive sheet of claim 1.