JP6587811B2 - Thermally peelable adhesive sheet - Google Patents

Description

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

  Conventionally, 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 solution from adhering to the non-treated surface of the copper foil. Further, when the surface of the glass substrate is polished with an acid such as hydrofluoric acid, an adhesive sheet is attached to the non-treated surface. In such a pressure sensitive adhesive sheet, when a chemical solution enters the pressure sensitive adhesive sheet, the interface between the pressure sensitive adhesive layer and other layers, the invading chemical solution is a factor of outgas in the post-process after chemical treatment. Or the additive material in the pressure-sensitive adhesive layer may be altered. For example, in the pressure-sensitive adhesive layer containing thermally expandable microspheres (foaming agent) that is added to develop removability as described in Patent Document 1, the foaming agent is treated with an acidic or alkaline chemical solution. However, there is a problem that the foaming function is lost due to chemical alteration.

JP 2001-019915 A

  The present invention has been made to solve the above-described conventional problems, and a main object thereof is to provide a heat-peelable pressure-sensitive adhesive sheet (heat-peelable pressure-sensitive adhesive sheet) including a pressure-sensitive adhesive layer that is difficult for chemicals to enter. There is.

The heat-peelable pressure-sensitive adhesive sheet of the present invention comprises a first pressure-sensitive adhesive layer, a base material, and a second pressure-sensitive adhesive layer in this order, and the first pressure-sensitive adhesive layer comprises a (meth) acrylic polymer. A structural unit derived from an alkyl (meth) acrylate ester having an alkyl group having 2 or more carbon atoms, and an OH group. The (meth) acrylic monomer-derived structural unit, and in the (meth) acrylic polymer, the molar ratio (C / OH) of carbon (C) to OH group of the side chain alkyl group is 40 to 150. It is.
In one embodiment, the second pressure-sensitive adhesive layer includes the thermally expandable microsphere.
In one embodiment, the center line average surface roughness Ra of the first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer is 1 μm or less.
In one embodiment, the contact angle of water with respect to the first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer is 85 ° to 115 °.
In one embodiment, the first pressure-sensitive adhesive layer contains a tackifier, and the content of the tackifier is 40 parts by weight or less with respect to 100 parts by weight of the first pressure-sensitive adhesive layer. is there.
In one embodiment, the second pressure-sensitive adhesive layer contains a tackifier, and the content of the tackifier is 40 parts by weight or less with respect to 100 parts by weight of the second pressure-sensitive adhesive layer. is there.
In one embodiment, the gel fraction of the first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer is 50% or more.
In one embodiment, the adhesive force in 23 degreeC at the time of sticking the said 1st adhesive layer side to a polyethylene terephthalate film is 1 N / 20mm or more.
According to another aspect of the present invention, an electronic component is provided. This electronic component is manufactured using the heat-peelable pressure-sensitive adhesive sheet.

  In the present invention, a (meth) acrylic compound containing a structural unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 2 or more carbon atoms and a structural unit derived from a (meth) acrylic monomer having an OH group. By forming a pressure-sensitive adhesive layer containing a polymer as a base polymer, and setting the molar ratio (C / OH) of carbon (C) to OH group of the side chain alkyl group in the (meth) acrylic polymer to a specific range Further, it is possible to provide a heat-peelable pressure-sensitive adhesive sheet that includes a pressure-sensitive adhesive layer that is difficult for chemicals to enter and that has excellent adhesive strength. Moreover, since the adhesive sheet of this invention is equipped with the adhesive layer containing a thermally expansible microsphere, it expresses the outstanding peelability by heating. Furthermore, in the present invention, since it is difficult for the chemical solution to enter the pressure-sensitive adhesive layer, the function of the heat-expandable microsphere is also used in applications where the chemical solution is exposed to an acidic or alkaline chemical solution (for example, for protection during etching). Can be provided, and a heat-peelable pressure-sensitive adhesive sheet in which adhesiveness and peelability are highly compatible can be provided.

1 is a schematic cross-sectional view of a heat-peelable pressure-sensitive adhesive sheet according to one embodiment of the present invention. It is a schematic sectional drawing of the heat peelable adhesive sheet by another embodiment of this invention.

A. Overall configuration diagram 1 of a heat-peelable pressure-sensitive adhesive sheet is a schematic cross-sectional view of the heat-peelable pressure-sensitive adhesive sheet according to one embodiment of the present invention. The heat-peelable pressure-sensitive adhesive sheet 100 includes a first pressure-sensitive adhesive layer 10, a base material 20, and a second pressure-sensitive adhesive layer 30 in this order. The first pressure-sensitive adhesive layer 10 includes thermally expandable microspheres. Since the heat-expandable microspheres expand or foam when heated, the pressure-sensitive adhesive layer containing the heat-expandable microspheres decreases in adhesive strength when heated. The heat-peelable pressure-sensitive adhesive sheet of the present invention includes a pressure-sensitive adhesive layer containing thermally expandable microspheres, so that the adherend can be easily heated by heating even when the adherend is attached to both surfaces. The adherend can be prevented from being damaged. The thermally expandable microspheres can also be included in the second pressure-sensitive 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 provided adjacent to the first pressure-sensitive adhesive layer 10 or the second pressure-sensitive adhesive layer 30. Preferably, the elastic layer 40 is provided adjacent to an adhesive layer containing thermally expandable microspheres. In one embodiment, it is provided between the 1st adhesive layer 10 and the base material 20 like the example of illustration. By providing the elastic layer, the followability to an adherend having an uneven surface is improved. Further, if the elastic layer is provided adjacent to the pressure-sensitive adhesive layer containing thermally expandable microspheres, deformation (expansion) in the surface direction of the pressure-sensitive adhesive layer when heated at the time of peeling is restricted, and deformation in the thickness direction is prevented. have priority. 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 outside the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface until it is used.

  The adhesive strength at 23 ° C. when the first pressure-sensitive adhesive layer side of the heat-peelable pressure-sensitive adhesive sheet of the present invention is attached to a polyethylene terephthalate (PET) film is preferably 1 N / 20 mm or more, more preferably 3 N / It is 20 mm-20 N / 20 mm, More preferably, it is 4 N / 20 mm-10 N / 20 mm. Within such a range, a useful heat-peelable pressure-sensitive adhesive sheet can be obtained as a temporary protective pressure-sensitive adhesive sheet. In this specification, the adhesive strength refers to an adhesive strength measured by a method according to JIS Z 0237: 2000. A specific measuring method will be described later. The heat-peelable pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet whose adhesive strength is reduced by heating. The “adhesive strength at 23 ° C.” refers to the adhesive strength before the adhesive strength is reduced.

B. 1st adhesive layer The said 1st adhesive layer contains the acrylic adhesive I containing the (meth) acrylic-type polymer as a base polymer, and a thermally expansible microsphere.

B-1. Acrylic adhesive I
<(Meth) acrylic polymer>
The (meth) acrylic polymer contained in the acrylic pressure-sensitive adhesive I includes (meth) acrylic acid alkyl ester (a) having an alkyl group having 2 or more carbon atoms and (meth) acrylic monomer having an OH group. A polymer obtained using (b) as a monomer component is used.

  Specific examples of the (meth) acrylic acid alkyl ester (a) include ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid. Isobutyl, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, (meta ) 2-ethylhexyl acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, ( (Meth) acrylic acid dodecyl, (meth) acrylic acid tridecyl, (meth) acrylic acid Radeshiru, (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl include (meth) eicosyl acrylate. The (meth) acrylic acid alkyl ester (a) may be used alone or in combination of two or more.

  Carbon number of the alkyl group which the said (meth) acrylic-acid alkylester (a) has is 2 or more as above-mentioned, Preferably it is 4 or more, More preferably, it is 4-20, More preferably, it is 6-18. It is. By using the (meth) acrylic acid alkyl ester (a) having such an alkyl group, a pressure-sensitive adhesive layer in which a chemical solution (for example, an acidic or alkaline chemical solution) is difficult to enter can be formed.

  Specific examples of the (meth) acrylic monomer (b) having an OH group include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and hydroxyhexyl (meth) acrylate. , Hydroxyoctyl (meth) acrylate, hydroxydecyl (meth) acrylate, hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl methacrylate, and the like. As the (meth) acrylic monomer (b), carboxyl group-containing (meth) acrylic monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid are used. Also good. The (meth) acrylic monomer (b) may be used alone or in combination of two or more.

  The (meth) acrylic polymer contained in the acrylic pressure-sensitive adhesive I may contain the (meth) acrylic acid alkyl ester (a) and the methacrylic acid ester (a) and A constitutional unit corresponding to another monomer copolymerizable with (/) (meth) acrylic monomer (b) may be included. Examples of such monomers include methyl (meth) acrylate; acid anhydride monomers such as maleic anhydride and itaconic anhydride; styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid , (Meth) acrylamide propanesulfonic acid, sulfopropyl (meth) acrylate, sulfonic acid group-containing monomers such as (meth) acryloyloxynaphthalenesulfonic acid; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (N-substituted) amide monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; aminoethyl (meth) acrylate, N, N-dimethyl (meth) acrylate Aminoethyl, (meth) a (Meth) acrylic acid aminoalkyl monomers such as t-butylaminoethyl acrylate; (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl; N-cyclohexylmaleimide , N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and other maleimide monomers; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexyl Itaconimide monomers such as itaconimide, N-cyclohexyl itaconimide, N-lauryl itaconimide; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylenes Succinimide monomers such as synimide and N- (meth) acryloyl-8-oxyoctamethylene succinimide; vinyl acetate, vinyl propionate, N-vinyl pyrrolidone, methyl vinyl pyrrolidone, vinyl pyridine, vinyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine Vinyl monomers such as vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine, N-vinyl carboxylic acid amides, styrene, α-methyl styrene, N-vinyl caprolactam; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl acrylate; polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate , Glycol-based acrylic ester monomers such as (meth) acrylic acid methoxyethylene glycol and (meth) acrylic acid methoxypolypropylene glycol; (meth) acrylic acid tetrahydrofurfuryl, fluorine (meth) acrylate, and heterocyclic rings such as silicone (meth) acrylate Acrylate monomer having halogen atom, silicon atom, etc .; hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di ( (Meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol Hexa (meth) acrylate, epoxy acrylate, polyester acrylate, a polyfunctional monomer such as urethane acrylate; isoprene, butadiene, olefin monomer isobutylene and the like; vinyl ether monomers such as vinyl ether. These monomer components may be used alone or in combination of two or more.

  The (meth) acrylic polymer contained in the acrylic pressure-sensitive adhesive I includes a (meth) acrylic acid alkyl ester (a) having an alkyl group having 2 or more carbon atoms and a (meth) acrylic monomer having an OH group ( It is obtained by polymerizing b) and another monomer (c) used as necessary by any appropriate polymerization method. The (meth) acrylic polymer thus obtained has a (meth) acrylic acid having an alkyl group having 2 or more carbon atoms (preferably 4 or more, more preferably 4 to 20, more preferably 6 to 18). A structural unit A derived from an alkyl ester and a structural unit B derived from a (meth) acrylic monomer having an OH group are included. 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 containing the structural unit A and the structural unit B is preferably 50 parts by weight to 100 parts by weight with respect to 100 parts by weight of the solid content in the acrylic pressure-sensitive adhesive I. Preferably it is 60 weight part-98 weight part, More preferably, it is 65 weight part-90 weight part.

  The content ratio of the structural unit A derived from the (meth) acrylic acid alkyl ester having an alkyl group having 2 or more carbon atoms is preferably 70 parts by weight to 98 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. More preferably, it is 80 weight part-95 weight part, More preferably, it is 85 weight part-95 weight part.

  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, more preferably 2 parts per 100 parts by weight of the (meth) acrylic polymer. Parts by weight to 20 parts by weight, more preferably 3 parts by weight to 10 parts by weight.

In the (meth) acrylic polymer contained in the acrylic pressure-sensitive adhesive I, the molar ratio (C / OH) of carbon (C) to OH group of the side chain alkyl group is preferably 40 to 150, more preferably. Is 42 to 120, more preferably 50 to 100, particularly preferably 55 to 80, and most preferably 55 to 75. The molar ratio (C / OH) of the monomer forming the structural unit having a side chain alkyl group (that is, (meth) acrylic acid alkyl ester (a), optionally used (meth) acrylic acid methyl ester) It is calculated | required from the compounding quantity, the molecular weight, the number of side chain alkyl groups, and the compounding quantity, molecular weight, and number of OH groups of the (meth) acrylic-type monomer (b) which has OH group. For example, the monomer a ₁ , the monomer a ₂ and the monomer a ₃ are used as the monomer forming the structural unit having a side chain alkyl group, and the monomer b ₁ and the monomer b ₂ are used as the (meth) acrylic monomer (b). In this case, the molar ratio (C / OH) can be obtained by the following formula (1).

  In the present invention, by adding a predetermined amount of an alkyl group having 2 or more carbon atoms to the (meth) acrylic polymer as the base polymer, the polarity of the pressure-sensitive adhesive layer is lowered, and a chemical solution (for example, acidic or alkaline) Infiltration of the chemical solution) can be prevented. On the other hand, when the polarity of the pressure-sensitive adhesive layer is too low, sufficient adhesive strength cannot be obtained. However, in the present invention, the (meth) acrylic polymer further contains an OH group, and the side chain alkyl group carbon ( When the molar ratio (C / OH) between C) and the OH group is in the above range, it is possible to prevent the chemical solution from entering the adhesive layer while maintaining the adhesiveness. The heat-peelable pressure-sensitive adhesive sheet of the present invention having the above-mentioned pressure-sensitive adhesive layer that can express excellent adhesiveness by containing a predetermined amount of OH groups is also effective for chemical solution intrusion into the interface between the pressure-sensitive adhesive sheet and the adherend. Can be prevented. If the chemical solution is prevented from entering, deterioration of the adhesive can be suppressed, so that excellent adhesiveness can be maintained. Moreover, since the alteration of the thermally expandable microspheres in the pressure-sensitive adhesive layer due to the chemical solution can be suppressed, the thermal peelability is not impaired even when used in an acidic or alkaline chemical solution. Furthermore, the pressure-sensitive adhesive composed of the (meth) acrylic polymer is difficult to inhibit the expansion or foaming of the thermally expandable microsphere. The heat-peelable pressure-sensitive adhesive sheet that exhibits these effects can be suitably used as a protective sheet in a process using an acidic or alkaline chemical solution, such as an etching process.

  The weight average molecular weight of the (meth) acrylic polymer (a value measured by gel permeation chromatography (solvent: THF) using a standard polystyrene calibration curve) is preferably in the range of 100,000 to 3,000,000 in terms of polystyrene. More preferably, it is 200,000 to 2.5 million, and more preferably 300,000 to 2,000,000.

<Additives>
The acrylic pressure-sensitive adhesive I can contain any appropriate additive as required. Examples of the additive include a crosslinking agent, a tackifier, a plasticizer (for example, trimellitic acid ester plasticizer, pyromellitic acid ester plasticizer), pigment, dye, filler, anti-aging agent, conductive material. , Antistatic agents, ultraviolet absorbers, light stabilizers, release modifiers, softeners, surfactants, flame retardants, antioxidants and the like.

  Any appropriate tackifier is used as the tackifier. As the tackifier, for example, a tackifier resin is used. Specific examples of tackifying resins include rosin tackifying resins (eg, unmodified rosin, modified rosin, rosin phenolic resin, rosin ester resin, etc.), terpene tackifying resins (eg, terpene resins, terpene phenols). Resin, styrene modified terpene resin, aromatic modified terpene resin, hydrogenated terpene resin), hydrocarbon tackifier resin (for example, aliphatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, aromatic resin) Hydrocarbon resins (eg, styrene resins, xylene resins, etc.), aliphatic / aromatic petroleum resins, aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone resins, coumarone indene resins Etc.), phenolic tackifying resins (eg, alkylphenolic resins, xyleneformaldehyde resins, resoles, novos) Tsu, etc. h), ketone-based tackifying resins, polyamide-based tackifying resins, epoxy-based tackifying resins, such as an elastomer-based tackifying resins. Among these, rosin-based tackifier resins, terpene-based tackifier resins, or hydrocarbon-based tackifier resins (such as styrene resins) are preferable. You may use a tackifier individually or in combination of 2 or more types.

  A commercially available product may be used as the tackifier. Specific examples of commercially available tackifiers include terpene phenol resins such as “YS Polystar S145” and “Mighty Ace K140” manufactured by Yasuhara Chemical Co., Ltd. and “Tamanor 901” manufactured by Arakawa Chemical Co., Ltd .; Sumitomo Bakelite Co., Ltd. Rosin phenolic resins such as “Sumilite Resin PR-12603” manufactured by Arakawa Chemical Co., Ltd .; Alkylphenol resins such as “Tamanol 1010R” and “Tamanol 200N” manufactured by Arakawa Chemical Co., Ltd. An alicyclic saturated hydrocarbon resin such as trade name “Arcon P-140” manufactured by Arakawa Chemical Co., Ltd.

  The addition amount of the tackifier 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, more preferably 100 parts by weight of the pressure-sensitive adhesive layer. Is 15 to 25 parts by weight. If it is such a range, the adhesive layer which is excellent in adhesive force and uneven | corrugated followable | trackability can be formed. If a pressure-sensitive adhesive layer excellent in unevenness followability is formed, chemical solution intrusion between the pressure-sensitive adhesive layer and the adherend is remarkably prevented.

  The hydroxyl value of the tackifier is preferably 10 mgKOH / g or more, more preferably 40 mgKOH / g to 400 mgKOH / g. If it is such a range, adhesiveness and prevention of chemical | medical solution penetration | invasion will be compatible, and the effect of this invention will become remarkable.

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

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

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

B-2. Thermally expandable microspheres Thermally expandable microspheres are microspheres that can expand or foam by heating. The heat-peelable pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer containing the thermally expandable microspheres has sufficient adhesive strength in a scene where adhesive force is required because heating causes unevenness on the sticking surface and decreases the adhesive strength. In addition, it is excellent in releasability in scenes that require peeling. As described above, in the present invention, even when exposed to an acidic or alkaline chemical solution, the heat-expandable microspheres are hardly altered, and the functions as the heat-expandable microspheres can be sufficiently expressed.

  The content ratio of the heat-expandable microspheres can be appropriately set according to the desired decrease in adhesive strength. The content ratio of the heat-expandable microsphere is, for example, 1 part by weight to 150 parts by weight, preferably 10 parts by weight to 130 parts by weight, with respect to 100 parts by weight of the (meth) acrylic polymer in the acrylic adhesive I. More preferably, it is 25 to 100 parts by weight.

  Any appropriate thermally expandable microsphere can be used as the thermally expandable microsphere. As the thermally expandable microsphere, for example, a microsphere in which a substance that easily expands by heating is encapsulated in an elastic shell can be used. Such thermally expandable microspheres can be produced by any appropriate method, for example, a coacervation method, an interfacial polymerization method, or the like.

  Examples of the material that easily expands by heating include propane, propylene, butene, normal butane, isobutane, isopentane, neopentane, normal pentane, normal hexane, isohexane, heptane, octane, petroleum ether, methane halide, tetraalkylsilane. And low-boiling-point liquids such as azodicarbonamide that is gasified by thermal decomposition.

  Examples of the substance constituting the shell include nitrile monomers such as acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethoxyacrylonitrile, fumaronitrile; acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, Carboxylic acid monomers such as citraconic acid; vinylidene chloride; vinyl acetate; methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, (Meth) acrylic acid esters such as isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, β-carboxyethyl acrylate; styrene monomers such as styrene, α-methylstyrene, chlorostyrene ; It includes polymer composed like; acrylamides, substituted acrylamides, methacrylamide, amide monomers such as 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, methyl methacrylate-acrylonitrile copolymer, acrylonitrile-methacrylonitrile-itaconic acid copolymer. A polymer etc. are mentioned.

  An inorganic foaming agent or an organic foaming agent may be used as the thermally expandable microsphere. Examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, various azides and the like. Examples of the organic foaming agent include chlorofluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate. Hydrazine-based compounds such as paratoluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonyl hydrazide, 4,4′-oxybis (benzenesulfonyl hydrazide), allyl bis (sulfonyl hydrazide); p-toluylene sulfonyl semicarbazide, 4, Semicarbazide compounds such as 4′-oxybis (benzenesulfonyl semicarbazide); Triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; N, N′-dinitrosopentamethylenetetramine, N, '- dimethyl -N, N'-dinitrosoterephthalamide; etc. N- nitroso compounds, and the like.

  A commercially available product may be used as the thermally expandable microsphere. Specific examples of commercially available thermally expandable microspheres are trade names “Matsumoto Microsphere” (grade: F-30, F-30D, F-36D, F-36LV, F-50, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.). F-50D, F-65, F-65D, FN-100SS, FN-100SSD, FN-180SS, FN-180SSD, F-190D, F-260D, F-2800D), trade names “Nippon Philite” "Expansel" (grade: 053-40, 031-40, 920-40, 909-80, 930-120), "Die Form" (grade: H750, H850, H1100, S2320D, S2640D, manufactured by Kureha Chemical Industry Co., Ltd.) M330, M430, M520), “ADVANCEL” manufactured by Sekisui Chemical Co., Ltd. (grade: EML101, EMH204, EHM3) 1, EHM302, EHM303, EM304, EHM401, EM403, EM501) and the like.

  The particle diameter of the thermally expandable microsphere 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 particularly preferably 10 μm to 15 μm. . Therefore, the particle size before heating of the thermally expandable microspheres is preferably 6 μm to 45 μm, more preferably 15 μm to 35 μm, in terms of the average particle size. The above particle diameter and average particle diameter are values obtained by the particle size distribution measurement method in the laser scattering method.

  The thermally expandable microsphere preferably has an appropriate strength that does not rupture until the volume expansion coefficient is preferably 5 times or more, more preferably 7 times or more, and even more preferably 10 times or more. When such a heat-expandable microsphere is used, the adhesive force can be efficiently reduced by heat treatment.

B-3. The thickness of the first pressure-sensitive adhesive layer such as the characteristics of the first pressure-sensitive adhesive layer is preferably 1 μm to 100 μm, more preferably 5 μm to 80 μm, and particularly preferably 10 μm to 50 μm. As described above, the first pressure-sensitive adhesive layer is a layer containing thermally expandable microspheres. Therefore, the thickness of the first pressure-sensitive adhesive layer is determined by observing the cross-section in the thickness direction of the first pressure-sensitive adhesive layer, the outer surface of the first pressure-sensitive adhesive layer (the surface opposite to the substrate), and the base The distance to the innermost end of the thermally expandable microsphere closest to the material.

  The difference (thickness-average particle diameter) between the thickness of the first pressure-sensitive adhesive layer and the average particle diameter of the thermally expandable microspheres contained in the first pressure-sensitive adhesive layer is preferably 8 μm or more, and more Preferably it is 10 micrometers or more, More preferably, it is 15 micrometers or more, Especially preferably, it is 20 micrometers or more, Most preferably, they are 25 micrometers-100 micrometers. Within such a range, the first pressure-sensitive adhesive layer has an appropriate surface roughness, and a heat-peelable pressure-sensitive adhesive sheet in which the chemical liquid does not easily enter the interface between the first pressure-sensitive adhesive layer and the adherend is provided. Obtainable.

  The elastic modulus at 25 ° C. of the first pressure-sensitive adhesive layer 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. is there. When the elastic modulus of the pressure-sensitive adhesive layer is in the above range, a heat-peelable pressure-sensitive adhesive sheet that is excellent in pressure-sensitive adhesiveness, cutability, and step following property can be obtained. The elastic modulus by the nano-indentation method means that the load and indentation depth applied to the indenter when the indenter is pushed into the sample are continuously measured during loading and unloading, and the obtained load load minus indentation depth. It refers to the elastic modulus obtained from the height curve. In this specification, the elastic modulus by the nanoindentation method means an elastic modulus measured as described above under the measurement conditions of load: 1 mN, load / unloading speed: 0.1 mN / s, and holding time: 1 s.

  The elastic modulus of the first pressure-sensitive adhesive layer can be adjusted by the composition of the base polymer constituting the pressure-sensitive adhesive in the pressure-sensitive adhesive layer. Further, the elastic modulus may be adjusted by adding an additive to the first pressure-sensitive adhesive layer. For example, if the first pressure-sensitive adhesive layer contains beads, the elastic modulus of the pressure-sensitive 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 amount of beads added is, for example, 10 to 200 parts by weight, preferably 20 to 100 parts by weight, with respect to 100 parts by weight of the entire pressure-sensitive adhesive layer.

  The center line average surface roughness Ra of the sticking surface of the first pressure-sensitive adhesive layer is preferably 1 μm or less, more preferably 0.01 μm to 1 μm, and further preferably 0.03 μm to 0.8 μm. It is particularly preferably 0.06 μm to 0.6 μm. If it is such a range, the heat | fever exfoliation-type adhesive sheet which a chemical | medical solution cannot penetrate | invade easily into the interface of a 1st adhesive layer and a to-be-adhered body can be obtained. The surface roughness Ra is measured according to JIS B 0601.

  The contact angle of water with the first pressure-sensitive adhesive layer is preferably 85 ° to 115 °, more preferably 87 ° to 115 °, and particularly preferably 90 ° to 115 °. When the contact angle of water is larger than 115 °, that is, when the pressure-sensitive adhesive layer is highly hydrophobic, there is a possibility that sufficient adhesive properties cannot be obtained. On the other hand, when the contact angle of water is smaller than 85 °, that is, when the hydrophobicity of the pressure-sensitive adhesive layer is too low, the chemical solution may enter the interface between the pressure-sensitive adhesive layer and the adherend.

  The gel fraction of the first pressure-sensitive adhesive layer is preferably 50% or more, more preferably 52% to 99%, and further preferably 55% to 99%. If it is such a range, the chemical | medical solution penetration | invasion to an adhesive layer can be prevented. The gel fraction of the pressure-sensitive adhesive layer can be adjusted by controlling the composition of the base polymer constituting the pressure-sensitive adhesive, the type and content of the crosslinking agent, the type and content of the tackifier, and the like. A 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 pressure-sensitive adhesive contained in the second pressure-sensitive adhesive layer, from the viewpoint of adhesion, and when the second pressure-sensitive adhesive layer contains thermally expanded microspheres, the thermally expanded microspheres expand or foam during heating. From an unconstrained viewpoint, for example, acrylic adhesive, rubber adhesive, vinyl alkyl ether adhesive, silicone adhesive, polyester adhesive, polyamide adhesive, urethane adhesive, styrene-diene block copolymer Examples of system adhesives and active energy ray-curable adhesives. The pressure-sensitive adhesive may be a creep property improving pressure-sensitive adhesive blended with a heat-meltable resin having a melting point of about 200 ° C. or less. Details of the creep property-improving pressure-sensitive adhesive are described in JP-A-56-61468, JP-A-63-17981, and the like. Among the above adhesives, an acrylic adhesive or a rubber adhesive can be preferably used. In addition, you may use the said adhesive individually or in combination of 2 or more types.

  Any appropriate acrylic pressure-sensitive adhesive can be used as the acrylic pressure-sensitive adhesive contained in the second pressure-sensitive adhesive layer. For example, an acrylic pressure-sensitive adhesive having an acrylic polymer (homopolymer or copolymer) using one or more (meth) acrylic acid alkyl ester as a monomer component as a base polymer may be used. In one embodiment, the acrylic pressure-sensitive adhesive I described in the above section B is used.

  Examples of the rubber-based adhesive include natural rubber; polyisoprene rubber, styrene / butadiene (SB) rubber, styrene / isoprene (SI) rubber, styrene / isoprene / styrene block copolymer (SIS) rubber, and 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 Examples thereof include rubber-based pressure-sensitive adhesives based on polymer (SEP) rubber, recycled rubber, butyl rubber, polyisobutylene, synthetic rubbers such as modified products thereof, and the like.

  As the pressure-sensitive adhesive contained in the second pressure-sensitive adhesive layer, an active energy ray-curable pressure-sensitive adhesive that can be cured (high elastic modulus) by irradiation with active energy rays may be used. When using an active energy ray-curable adhesive, a heat-releasable type that has low elasticity, high flexibility and excellent handleability when affixed, and can reduce adhesive strength by irradiating active energy rays in situations where peeling is required An adhesive sheet can be obtained. Examples of the active energy rays include gamma rays, ultraviolet rays, visible rays, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flows, ionizing rays, particle rays and the like.

  Examples of the resin material constituting the active energy ray-curable pressure-sensitive adhesive include, for example, an ultraviolet curing system (by Kayo Kiyomi, General Technology Center, (1989)), photocuring technology (Technical Information Association (2000)), The resin material described in Unexamined-Japanese-Patent No. 2003-292916, patent 4151850, etc. is mentioned. More specifically, a resin material (R1) containing a polymer as a base material and an active energy ray reactive compound (monomer or oligomer), a resin material (R2) containing an active energy ray reactive polymer, and the like can be mentioned.

  Examples of the base polymer include natural rubber, polyisobutylene rubber, styrene / butadiene rubber, styrene / isoprene / styrene block copolymer rubber, recycled rubber, butyl rubber, polyisobutylene rubber, and nitrile rubber (NBR). Examples thereof include rubber polymers; silicone polymers; acrylic polymers. These polymers may be used alone or in combination of two or more.

  As said active energy ray reactive compound, the photoreactive monomer or oligomer which has a functional group which has carbon-carbon multiple bonds, such as an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, an acetylene group, is mentioned, for example. Specific examples of the photoreactive monomer or oligomer include trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipenta Erythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, etc. (Meth) acryloyl group-containing compound; 2 to 5 mer of the (meth) acryloyl group-containing compound; and the like.

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

  Furthermore, 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 heterocyclic rings in the molecule may be used. In the mixture, an organic salt is cleaved by irradiation with active energy rays (for example, ultraviolet rays and electron beams) to generate ions, which act as starting species to cause a ring opening reaction of the heterocyclic ring to form a three-dimensional network structure. Can do. Examples of the organic salts include iodonium salts, phosphonium salts, antimonium salts, sulfonium salts, and borate salts. Examples of the heterocyclic ring in the compound having a plurality of heterocyclic rings in the molecule include oxirane, oxetane, oxolane, thiirane, aziridine and the like.

  Furthermore, 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 heterocyclic rings in the molecule may be used. In the mixture, an organic salt is cleaved by irradiation with active energy rays (for example, ultraviolet rays and electron beams) to generate ions, which act as starting species to cause a ring opening reaction of the heterocyclic ring to form a three-dimensional network structure. Can do. Examples of the organic salts include iodonium salts, phosphonium salts, antimonium salts, sulfonium salts, and borate salts. Examples of the heterocyclic ring in the compound having a plurality of heterocyclic rings in the molecule include oxirane, oxetane, oxolane, thiirane, aziridine and the like.

  In the resin material (R1) containing the polymer as the base material and the active energy ray-reactive compound, the content ratio of the active energy ray-reactive compound is preferably 0.00 with respect to 100 parts by weight of the polymer as the base material. 1 to 500 parts by weight, more preferably 1 to 300 parts by weight, and even more preferably 10 to 200 parts by weight.

  The resin material (R1) containing the polymer as the base material and the active energy ray-reactive compound may contain any appropriate additive as necessary. Examples of the additive include an active energy ray polymerization initiator, an active energy ray polymerization accelerator, a crosslinking agent, a plasticizer, and a vulcanizing agent. Any appropriate initiator may be used as the active energy ray polymerization initiator depending on the type of active energy ray used. The active energy ray polymerization initiators may be used alone or in combination of two or more. In the resin material (R1) containing the polymer as the base material and the active energy ray-reactive compound, the content ratio of the active energy ray polymerization initiator is preferably 0.1 with respect to 100 parts by weight of the polymer as the base material. Parts by weight to 10 parts by weight, more preferably 1 part by weight to 5 parts by weight.

  As said active energy ray reactive polymer, the polymer which has a functional group which has carbon-carbon multiple bonds, such as an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, an acetylene group, is mentioned, for example. Specific examples of the polymer having an active energy ray-reactive functional group include a polymer composed of a polyfunctional (meth) acrylate; a photocationic polymerization type polymer; a cinnamoyl group-containing polymer such as polyvinyl cinnamate; a diazotized amino novolak Resin; polyacrylamide; and the like. Further, as the resin material (R2) containing an active energy ray-reactive polymer, a mixture of an active energy ray-reactive polymer having an allyl group and a compound having a thiol group can also be used. As long as a pressure-sensitive adhesive layer precursor having practical hardness (viscosity) can be formed before curing by irradiation with active energy rays (for example, when a heat-peelable pressure-sensitive adhesive sheet is attached), the active energy ray reaction In addition to a polymer having a reactive functional group, 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 active energy ray-reactive compound (monomer or oligomer). Moreover, the resin material (R2) containing the said active energy ray reactive polymer may contain arbitrary appropriate additives as needed. The specific example of an additive is the same as that of the additive which can be contained in the resin material (R1) containing the polymer used as a base material, and an 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 parts by weight to 10 parts by weight with respect to 100 parts by weight of the active energy ray reactive polymer. More preferably, it is 1 to 5 parts by weight.

  The pressure-sensitive adhesive contained in the second pressure-sensitive adhesive layer may contain any appropriate additive as necessary. Examples of the additive used include the additive described in the above section B-1. Moreover, it is preferable that the addition amount of an additive (tackifier, a crosslinking agent, etc.) is also the addition amount explained in the section B-1. Therefore, in one embodiment, the second pressure-sensitive adhesive layer may contain a tackifier, and the content of the tackifier is preferably 40 parts by weight or less with respect to 100 parts by weight of the pressure-sensitive adhesive layer. More preferably 30 parts by weight or less, still more preferably 25 parts by weight or less, and still more preferably 3 parts by weight to 25 parts by weight.

C-2. Thermally expandable microspheres In one embodiment, the second pressure-sensitive adhesive layer further includes the thermally expandable microspheres described in Section B-2. Also in the second pressure-sensitive adhesive layer, the content ratio of the heat-expandable microspheres is, for example, 1 part by weight to 150 parts by weight with respect to 100 parts by weight of the base polymer in the pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer. Preferably they are 10 weight part-130 weight part, More preferably, they are 25 weight part-100 weight part.

C-3. The thickness of the second pressure-sensitive adhesive layer such as the characteristics of the second pressure-sensitive adhesive layer is preferably 1 μm to 100 μm, more preferably 5 μm to 80 μm, and particularly preferably 10 μm to 50 μm. When the second pressure-sensitive adhesive layer contains thermally expandable microspheres, the thickness of the second pressure-sensitive adhesive layer is observed in the thickness direction cross section of the second pressure-sensitive adhesive layer, similarly to the thickness of the first pressure-sensitive adhesive layer. The distance between the outer surface of the second pressure-sensitive adhesive layer (the surface on the side opposite to the substrate) and the innermost end of the thermally expandable microsphere closest to the substrate.

  When the second pressure-sensitive adhesive layer contains thermally expandable microspheres, the difference (thickness) between the thickness of the second pressure-sensitive adhesive layer and the average particle diameter of the thermally expandable microspheres contained in the second pressure-sensitive adhesive layer. The average particle diameter 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 at 25 ° C. of the second pressure-sensitive adhesive layer 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. is there.

  The center line average surface roughness Ra of the sticking surface of the second pressure-sensitive adhesive layer is preferably 1 μm or less, more preferably 0.01 μm to 1 μm, and further preferably 0.03 μm to 0.8 μm. It is particularly preferably 0.06 μm to 0.6 μm.

  The contact angle of water with the second pressure-sensitive adhesive layer is preferably 85 ° to 115 °, more preferably 87 ° to 115 °, and particularly preferably 90 ° to 115 °.

  The gel fraction of the second pressure-sensitive adhesive layer is preferably 50% or more, more preferably 52% to 99%, and further preferably 55% to 99%. If it is such a range, the chemical | medical solution penetration | invasion to an adhesive layer can be prevented.

D. As the substrate the base material, for example, a resin sheet, a nonwoven fabric, paper, metal foils, woven fabrics, rubber sheets, foam sheets, and the like. Moreover, you may use the base material comprised from these laminated bodies (especially laminated body containing a resin sheet), or the composite base material which used these several materials as a raw material. Examples of the resin constituting the resin sheet include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene- Vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyimide (PI), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), fluororesin, polyether ether ketone (PEEK) ), Urethane acrylate, acrylic resin (preferably UV curable acrylic resin), and the like. 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 fabrics, polyethylene resin nonwoven fabrics and ester resin nonwoven fabrics.

  The base material preferably has an elastic modulus of 10 MPa to 10 GPa at 25 ° C. by a nanoindentation method. The elastic modulus of the base material by the nanoindentation method at 25 ° C. is more preferably 100 MPa to 5 GPa, and particularly preferably 500 MPa to 5 GPa. Within such a range, it is possible to obtain a heat-peelable pressure-sensitive adhesive sheet that is excellent in cutability and handleability during bonding.

  The thickness of the substrate is preferably 1 μm to 1000 μm, more preferably 2 μm to 250 μm, and particularly preferably 10 μm to 100 μm. Within such a range, it is possible to obtain a heat-peelable pressure-sensitive adhesive sheet that is excellent in cutability and handleability during bonding.

  The base material may be subjected to a surface treatment. Examples of the surface treatment include corona treatment, chromic acid treatment, ozone exposure, flame exposure, high piezoelectric impact exposure, ionizing radiation treatment, coating treatment with an organic coating material, and the like. By performing such a surface treatment, the adhesiveness between the pressure-sensitive adhesive layer and the base material can be enhanced, and the chemical solution can be prevented from entering the interface between the pressure-sensitive adhesive layer and the base material. In particular, a coating treatment with an organic coating material is preferable because throwing destruction of the pressure-sensitive adhesive layer can be suppressed during heat peeling.

  Examples of the organic coating material include materials described in Plastic Hard Coat Material II (CMC Publishing Co., (2004)). Preferably, a urethane-based polymer, more preferably polyacryl urethane, polyester urethane, or a precursor thereof is used. This is because the coating on the base material is simple and various industrial products can be selected and obtained at low cost. The urethane polymer is, for example, a polymer composed of 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 contain a chain extender such as polyamine, an anti-aging agent, an oxidation stabilizer and the like as optional additives. Although the thickness of an organic coating layer is not specifically limited, For example, about 0.1 micrometer-10 micrometers are suitable, About 0.1 micrometer-5 micrometers are preferable, About 0.5 micrometer-5 micrometers are more preferable. As an organic coating material, Arakawa series manufactured by Arakawa Chemical Industry Co., Ltd. (for example, a combination of trade name “AP2500E” and trade name “CL2500” as a curing agent), trade name “NB300” manufactured by Dainichi Seika Co., Ltd., trade name “ Commercial products such as “HR color” may be used.

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, and an adhesive polymer can be used as the base polymer. Examples of the base polymer constituting the elastic layer include (meth) acrylic polymers: rubber polymers such as natural rubber and synthetic rubber (for example, nitrile, diene, and acrylic); Plastic elastomer, vinyl alkyl ether polymer, silicone polymer, polyester polymer, polyamide polymer, urethane polymer, styrene-diene block copolymer, ethylene-vinyl acetate copolymer, polyurethane polymer, polybutadiene, soft polychlorinated polymer Vinyl; radiation curable polymer and the like. The base polymer constituting the elastic layer may be the same as or different from the base polymer forming the pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer and / or second pressure-sensitive adhesive layer). The elastic layer may be a foamed film formed from the base polymer. The foamed film can be obtained by any appropriate method. The elastic layer and the first pressure-sensitive adhesive layer (and the second pressure-sensitive adhesive layer containing thermally expandable microspheres) are the presence or absence of thermally expandable microspheres (the elastic layer does not include thermally expandable microspheres). Can be distinguished.

  The (meth) acrylic polymer as the base polymer constituting the elastic layer is, for example, an acrylic polymer (homopolymer or copolymer) using one or more (meth) acrylic acid alkyl esters as monomer components. It is. Specific examples of the (meth) acrylic acid alkyl ester include (meth) acrylic acid alkyl esters having a linear or branched alkyl group having 20 or less carbon atoms. The acrylic polymer may contain units corresponding to other monomer components copolymerizable with the (meth) acrylic acid alkyl ester. Examples of such monomer components include acrylic acid, methacrylic acid, itotanic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N-methylolacrylamide, acrylonitrile, methacrylate. Examples include rhonitrile, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, styrene, isoprene, butadiene, isobutylene, and vinyl ether.

  The elastic layer may contain any appropriate additive as required. Examples of the additive include a crosslinking agent, a vulcanizing agent, a tackifier, a plasticizer, a softening agent, a filler, and an antiaging agent. When a hard resin such as polyvinyl chloride is used as the base polymer, it is preferable to form an elastic layer having desired elasticity by using a plasticizer and / or a softening agent in combination.

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

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

F. Manufacturing method of heat-peelable pressure-sensitive adhesive sheet The heat-peelable pressure-sensitive adhesive sheet of the present invention can be manufactured by any appropriate method. In the heat-peelable pressure-sensitive adhesive sheet of the present invention, for example, the first pressure-sensitive adhesive layer-forming composition is directly applied to one surface of the substrate, and the second pressure-sensitive adhesive is applied to the other surface of the substrate. Method for coating layer forming composition, coating layer formed by coating on any appropriate substrate, transferred to substrate, first adhesive layer and second adhesive layer The method of forming etc. are mentioned. In addition, the pressure-sensitive adhesive layer containing thermally expandable microspheres is formed by forming a pressure-sensitive adhesive coating layer with a composition containing a pressure-sensitive adhesive, and then sprinkling the heat-expandable microspheres on the pressure-sensitive adhesive coating layer, and then laminator, etc. May be used by embedding the thermally expandable microspheres in the coating layer.

  The first pressure-sensitive adhesive layer-forming composition contains the acrylic pressure-sensitive adhesive I and the thermally expandable microsphere, and optionally contains any appropriate solvent. The composition for forming the second pressure-sensitive adhesive layer contains any appropriate pressure-sensitive adhesive, and optionally contains the heat-expandable microspheres and / or any suitable solvent.

  When the heat-peelable pressure-sensitive adhesive sheet has the elastic layer, the elastic layer and the pressure-sensitive adhesive layer adjacent to the elastic layer, for example, apply the elastic layer-forming composition on the substrate, The composition for forming an adhesive layer can be applied and formed. For example, an elastic layer forming composition containing a material (base polymer, additive, etc.) for forming an elastic layer is applied on a substrate, and then the first layer is applied on the coating layer of the elastic layer forming composition. By applying the pressure-sensitive adhesive forming composition, the elastic layer and the first pressure-sensitive adhesive layer can be formed sequentially from the substrate side.

  Arbitrary appropriate coating methods may be employ | adopted as a coating method of each said composition. For example, each layer can be formed by drying after coating. Examples of the coating method include a coating method using 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. The heating temperature in the case of heating and drying can be set to any appropriate temperature according to the characteristics of the substance to be dried.

G. Applications The heat-peelable pressure-sensitive adhesive sheet of the present invention can be suitably used as a protective sheet for producing electronic components. In particular, when an electronic component is treated with an acidic or alkaline chemical (for example, etching treatment), it can be suitably used as a protective sheet for protecting the electronic component.

  The heat-peelable pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, and an electronic component as an object to be processed is attached to both surfaces of the pressure-sensitive adhesive sheet, and the electronic component is subjected to a processing step. Warpage can be prevented. Further, by performing the processing steps in this way, it is possible to improve the production efficiency.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In Examples, unless otherwise specified, “parts” and “%” are based on weight.

[Production 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, an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Chemical Company, trade name “Tetrad C”), 0.6 parts by weight, and a terpene phenol-based tackifier resin (manufactured by Yasuhara Chemical Co., Ltd.) Acrylic pressure-sensitive adhesive I (i) was prepared by mixing 30 parts by weight of “YS Polystar T130”.

[Production Examples 2 to 9] Preparation of acrylic pressure-sensitive adhesives I (ii) to (ix) (meth) acrylic polymers, crosslinking agents and tackifying resins shown in Table 1 were mixed in the blending amounts shown in Table 1. Acrylic adhesives I (ii) to (ix) were prepared.
Tetrad X: Epoxy crosslinking agent; manufactured by Mitsubishi Gas Chemical Company, trade name “Tetrad X”
Coronate L: Isocyanate-based crosslinking agent; manufactured by Nippon Polyurethane Industry Co., Ltd.
Superester A-75: Rosin-based tackifier resin; Arakawa Chemical Industries, trade name “Superester A-75”
TAMANOL 200: Alkylphenol tackifying 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 thermally expandable microspheres (trade name “Matsumoto Microsphere F-50D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) And 210 parts by weight of toluene were mixed to prepare an adhesive layer forming composition (i).
The pressure-sensitive adhesive layer forming composition (i) is applied to both sides of a PET film (trade name “Lumirror S10”, thickness: 100 μm, manufactured by Toray Industries, Inc.) as a base material, and a first pressure-sensitive adhesive having a thickness of 40 μm. An agent layer and a second pressure-sensitive adhesive layer were formed.
By the above operation, a heat-peelable pressure-sensitive adhesive sheet comprising a first pressure-sensitive adhesive layer (40 μm), a base material (100 μm), and a second pressure-sensitive adhesive layer (40 μm) was obtained in this order.

[Example 2]
130.6 parts by weight of the acrylic pressure-sensitive adhesive I (i) obtained in Production Example 1, and 30 parts by weight of thermally expandable microspheres (trade name “Matsumoto Microsphere F-48D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) Then, 210 parts by weight of toluene was mixed to prepare an adhesive layer forming composition (ii).
Moreover, as the elastic layer forming composition (i), a mixture of 130.6 parts by weight of acrylic pressure-sensitive adhesive I (i) and 210 parts by weight of toluene was prepared. Moreover, as the elastic layer forming composition (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) are arranged in this order on one side of a polyester film (trade name “Diafoil”, thickness: 50 μm, manufactured by Mitsubishi Plastics, Inc.) as a base material. Coating was performed to form an elastic layer (thickness: 20 μm) and a first pressure-sensitive adhesive layer (thickness: 40 μm). Furthermore, the elastic layer-forming composition (ii) and the pressure-sensitive adhesive layer-forming composition (ii) are applied in this order to the other surface of the substrate, and the elastic layer (thickness: 20 μm) and the second layer are applied. A pressure-sensitive adhesive layer (20 μm) was formed.
By the above operation, the first pressure-sensitive adhesive layer (40 μm), the elastic layer (20 μm), the base material (50 μm), the elastic layer (20 μm), and the second pressure-sensitive adhesive layer (20 μm) are arranged in this order. A heat-peelable pressure-sensitive adhesive sheet was obtained.

[Example 3]
151 parts by weight of the acrylic pressure-sensitive adhesive (iii) obtained in Production Example 3, 40 parts by weight of thermally expandable microspheres (trade name “Matsumoto Microsphere FN-100SD” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), and toluene 210 An adhesive layer forming composition (iii) was prepared by mixing with parts by weight.
In addition, 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 as the elastic layer forming composition (iii).
An elastic layer forming composition (iii) and an adhesive layer forming composition (iii) are applied in this order on one side of a PET film (trade name “Lumirror S10”, manufactured by Toray Industries, Inc., thickness: 100 μm) as a substrate. To form an elastic layer (thickness: 30 μm) and a first pressure-sensitive adhesive layer (thickness: 30 μm). Furthermore, the elastic layer-forming composition (iii) and the pressure-sensitive adhesive layer-forming composition (iii) are applied in this order to the other surface of the substrate, and the elastic layer (thickness: 15 μm) and the second layer are applied. The pressure-sensitive adhesive layer (thickness: 20 μm) was formed.
By the above operation, the first pressure-sensitive adhesive layer (30 μm), the elastic layer (30 μm), the base material (100 μm), the elastic layer (15 μm), and the second pressure-sensitive adhesive layer (20 μm) are arranged in this order. A heat-peelable pressure-sensitive adhesive sheet was obtained.

[Example 4]
122 parts by weight of the acrylic pressure-sensitive adhesive (v) obtained in Production Example 5, 30 parts by weight of thermally expandable microspheres (trade name “Expansel 909-DU80” manufactured by Nippon Philite Co., Ltd.), and 210 parts by weight of toluene And an adhesive layer forming composition (iv) were prepared.
In addition, 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 as the elastic layer forming composition (iv).
An elastic layer forming composition (iv) and an adhesive layer forming composition (iv) are applied in this order on one side of a PET film (trade name “Lumirror S10”, manufactured by Toray Industries, Inc., thickness: 50 μm) as a substrate. To form an elastic layer (thickness: 25 μm) and a first pressure-sensitive adhesive layer (thickness: 50 μm). Furthermore, the elastic layer-forming composition (iv) and the pressure-sensitive adhesive layer-forming composition (iv) are applied in this order to the other surface of the substrate, and the elastic layer (thickness: 20 μm) and the second layer are applied. The pressure-sensitive adhesive layer (thickness: 30 μm) was formed.
By the above operation, the first pressure-sensitive adhesive layer (50 μm), the elastic layer (25 μm), the base material (50 μm), the elastic layer (20 μm), and the second pressure-sensitive adhesive layer (30 μm) are arranged in this order. A heat-peelable pressure-sensitive adhesive sheet was obtained.

[Comparative Example 1]
140.7 parts by weight of the acrylic pressure-sensitive adhesive I (vii) obtained in Production Example 7, and 25 parts by weight of thermally expandable microspheres (trade name “Matsumoto Microsphere F-50D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) And 210 parts by weight of toluene were mixed to prepare an adhesive layer forming composition (v).
The pressure-sensitive adhesive layer forming composition (v) is applied to both sides of a PET film (trade name “Lumirror S10”, thickness: 100 μm, manufactured by Toray Industries, Inc.) as a base material to form a first pressure-sensitive adhesive having a thickness of 45 μm. An agent layer and a second pressure-sensitive adhesive layer were formed.
By the above operation, a heat-peelable pressure-sensitive adhesive sheet comprising a first pressure-sensitive adhesive layer (45 μm), a base material (100 μm), and a second pressure-sensitive adhesive layer (45 μm) in this order was obtained.

[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 thermally expandable microspheres (trade name “Expansel 909-DU80” manufactured by Nippon Philite Co., Ltd.) and 210 parts by weight of toluene The composition for adhesive layer formation (vi) was prepared by mixing the part.
Further, as the elastic layer forming composition (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.
An elastic layer forming composition (vi) and an adhesive layer forming composition (vi) are applied in this order on one side of a PET film (trade name “Lumirror S10”, manufactured by Toray Industries, Inc., thickness: 100 μm) as a base material. To form an elastic layer (thickness: 20 μm) and a first pressure-sensitive adhesive layer (thickness: 40 μm). Furthermore, the pressure-sensitive adhesive layer forming composition (vi) was applied to the other surface of the substrate to form a second pressure-sensitive adhesive layer (40 μm).
By the above operation, the heat-peelable pressure-sensitive adhesive sheet comprising the first pressure-sensitive adhesive layer (40 μm), the elastic layer (20 μm), the base material (100 μm), and the second pressure-sensitive adhesive layer (40 μm) in this order. Obtained.

[Evaluation]
The heat-peelable pressure-sensitive adhesive sheets obtained in the examples and comparative examples were subjected to the following evaluation. The results are shown in Table 2.
(1) Centerline average surface roughness Ra
The center line average surface roughness Ra on the first pressure-sensitive adhesive layer side was measured according to JIS B 0601. Specifically, using an optical surface roughness meter (trade name “Wyko NT9100”, manufactured by Veeco Metrology Group), the measurement conditions were measured as follows. Table 2 shows the average of the measurement values obtained by measuring the vertical and horizontal five times.
(Evaluation conditions)
Sample size: 50mm x 50mm
Measurement range: 2.534mm x 1.901mm
Measurement mode: VSL
Objective lens: 2.5 times Internal lens: 1.0 times (2) Contact angle Using a contact angle meter (trade name “CX-A type” manufactured by Kyowa Interface Co., Ltd.) in an environment of 23 ° C./50% RH, 2 μl of pure water was dropped on the surface of the first pressure-sensitive adhesive layer, and after 5 seconds of dropping, the contact angle of the droplet was measured. Table 2 shows the average of the measured values obtained by measuring five times.
(3) Gel fraction An evaluation sample 0.1 g sampled from the first resin layer was wrapped in a mesh-like sheet, allowed to stand at room temperature for 1 week in 50 ml of toluene, and toluene was immersed in the sample. . Thereafter, the toluene-insoluble matter was taken out and dried at 70 ° C. for 2 hours, and the toluene-insoluble matter after drying was weighed.
The gel fraction of the resin layer was calculated from the sample weight before immersion in toluene and the weight of toluene insoluble matter according to the following formula.
Gel fraction (%) = [(weight of insoluble toluene) / (weight of sample before immersion in toluene)] × 100
(4) Adhesive strength measurement method A heat-peelable pressure-sensitive adhesive sheet is cut into a size of width: 20 mm and length: 140 mm, and a polyethylene terephthalate film (trade name “Lumirror S” as an adherend is formed on the first pressure-sensitive adhesive layer. -10 ”manufactured by Toray Industries, Inc .; thickness: 25 μm, width: 20 mm) in accordance with JIS Z 0237 (2000) under an atmosphere of temperature: 23 ± 2 ° C. and humidity: 65 ± 5% RH, 2 kg roller Was reciprocated once and bonded together by pressure bonding. Next, the heat-peelable pressure-sensitive adhesive sheet with the adherend is set on a tensile tester with a thermostatic bath set at 23 ° C. (manufactured by Shimadzu Corporation, trade name “Shimadzu Autograph AG-120kN”) and left for 30 minutes. To do. After standing, the load when the adherend was peeled off from the heat-peelable pressure-sensitive adhesive sheet was measured at a temperature of 23 ° C. under the conditions of a peel angle of 180 ° and a peel speed (tensile speed) of 300 mm / min. The maximum load at that time (the maximum value of the load excluding the peak top in the initial measurement) was determined, and this maximum load was defined as the adhesive strength (N / 20 mm) of the first adhesive layer.
(5) Chemical solution intrusion evaluation The heat-peelable pressure-sensitive adhesive sheet is cut into a size of 50 mm × 50 mm, a silicon wafer is disposed on the first pressure-sensitive adhesive layer side, and a glass plate (thickness: 1 mm) on the second pressure-sensitive adhesive layer side Were placed under pressure at a temperature of 60 ° C., a pressure of 0.5 MPa, and a time of 3 minutes to prepare an evaluation sample. 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 chemical solution entering on the first pressure-sensitive adhesive layer side was evaluated based on the liquid penetration distance from the edge of the pressure-sensitive adhesive sheet.
(6) Heat peelability An evaluation sample was produced in the same manner as in the above (5) chemical solution penetration evaluation. The evaluation sample was heated at 130 ° C. for 1 minute. The peeling state of the silicon wafer after heating was confirmed visually. In Table 2, the case where the adhesive force of the pressure-sensitive adhesive layer was lost and the silicon wafer was peeled off was marked with ◯, and the case where the pressure-sensitive adhesive layer had a pressure-sensitive adhesive force and the silicon wafer was not peeled off was marked with x.

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

DESCRIPTION OF SYMBOLS 10 1st adhesive layer 20 Base material 30 2nd adhesive layer 40 Elastic layer 100,200 Thermally peelable adhesive sheet

Claims (9)

A first pressure-sensitive adhesive layer, a base material, and a second pressure-sensitive adhesive layer are provided in this order,
The first pressure-sensitive adhesive layer includes an acrylic pressure-sensitive adhesive containing a (meth) acrylic polymer and thermally expandable microspheres,
The (meth) acrylic polymer includes a structural unit derived from a (meth) acrylic acid alkyl ester having an alkyl group having 2 or more carbon atoms, and a structural unit derived from a (meth) acrylic monomer having an OH group,
In the (meth) acrylic polymer, the molar ratio (C / OH) of carbon (C) to OH group of the side chain alkyl group is 55 to 80 ,
The weight average molecular weight of the (meth) acrylic polymer is 100,000 to 3 million.
Thermally peelable adhesive sheet.   The heat-peelable pressure-sensitive adhesive sheet according to claim 1, wherein the second pressure-sensitive adhesive layer contains the thermally expandable microsphere.   The heat-peelable pressure-sensitive adhesive sheet according to claim 1 or 2, wherein a center line average surface roughness Ra of the first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer is 1 µm or less.   The heat-peelable pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein a contact angle of water with respect to the first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer is 85 ° to 115 °.   The first pressure-sensitive adhesive layer contains a tackifier, and the content of the tackifier is 40 parts by weight or less with respect to 100 parts by weight of the first pressure-sensitive adhesive layer. The heat-peelable pressure-sensitive adhesive sheet according to any one of the above.   The said 2nd adhesive layer contains a tackifier, and the content rate of this tackifier is 40 parts weight or less with respect to 100 weight part of this 2nd adhesive layer. The heat-peelable pressure-sensitive adhesive sheet according to any one of the above.   The heat-peelable pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein a gel fraction of the first pressure-sensitive adhesive layer and / or the second pressure-sensitive adhesive layer is 50% or more.   The heat-peelable pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein an adhesive force at 23 ° C when the first pressure-sensitive adhesive layer side is bonded to a polyethylene terephthalate film is 1 N / 20 mm or more.   An electronic component manufactured using the heat-peelable pressure-sensitive adhesive sheet according to claim 1.

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