JP5057678B2 - Thermally peelable adhesive sheet - Google Patents

Description

  The present invention relates to a heat-peelable pressure-sensitive adhesive sheet, and more particularly, to a heat-peelable pressure-sensitive adhesive sheet that can reduce contamination of an adherend after peeling by heat treatment.

  Conventionally, a heat-peelable pressure-sensitive adhesive sheet is known in which a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) containing a foaming agent (or a swelling agent) such as thermally expandable microspheres is provided on at least one surface of a substrate (patent) Reference 1 to Patent Document 5). The heat-peelable pressure-sensitive adhesive sheet has both adhesiveness before heating and peelability after heating. Accordingly, in the heat-peelable pressure-sensitive adhesive sheet, after achieving the purpose of bonding the article, the foaming agent-containing pressure-sensitive adhesive layer expands or expands by heating the pressure-sensitive adhesive layer containing the foaming agent (foaming agent-containing pressure-sensitive adhesive layer). The surface of the foaming agent-containing pressure-sensitive adhesive layer changes to an uneven shape, thereby reducing the adhesion area with the adherend (article), and reducing the adhesion area reduces the adhesive force, allowing the adherend to be easily separated. In this way, it is used in a wide variety of applications such as temporary fixing during the manufacturing process of electronic parts and semiconductor chips, and logistics such as transportation.

Japanese Utility Model Publication No. 50-13878 Japanese Patent Publication No.51-24534 JP-A-56-61468 JP-A-56-61469 JP 60-252681 A

  However, when a conventional heat-peelable pressure-sensitive adhesive sheet is used, the pressure-sensitive adhesive component (particularly, the base polymer of the heat-expandable pressure-sensitive adhesive layer) remains on the adherend from which the heat-peelable pressure-sensitive adhesive sheet has been peeled off by heat treatment. In some cases, it caused contamination problems and was not suitable for practical use.

  Accordingly, an object of the present invention is to provide a heat-peelable pressure-sensitive adhesive sheet that can reduce contamination of an adherend after peeling by heat treatment.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that the surface of the thermally expandable microsphere and the adhesive component (thermal component) are used as the thermally expandable microsphere. The adhesive property with the base polymer of the expandable pressure-sensitive adhesive layer, etc.) can be improved, and the cohesive failure of the pressure-sensitive adhesive component when the heat-expandable microspheres are expanded or expanded by the heat treatment can be suppressed or prevented. It was found that the adherend from which the heat-peelable pressure-sensitive adhesive sheet was peeled off by heat treatment was suppressed or prevented from being contaminated by the transfer of the pressure-sensitive adhesive component to the surface. The present invention has been completed based on these findings.

That is, the present invention is a heat-peelable pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer containing thermally expandable microspheres is provided on at least one surface of a substrate, wherein the thermally expandable microspheres are a base polymer of the adhesive The heat-peelable pressure-sensitive adhesive sheet is characterized by being thermally expandable microspheres surface-treated with an acrylic polymer and / or a rosin-based resin .

In the present invention, the heat-expandable microspheres, an acrylic polymer containing a functional group which can be used as a base polymer tacky Chakuzai, and / or have been surface treated with rosin-based resin containing a functional group Thermally expandable microspheres are preferred. In addition to the above-described invention, the present specification includes a heat-peelable pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer containing heat-expandable microspheres is provided on at least one surface of a base material. A heat-peelable pressure-sensitive adhesive sheet, wherein the microsphere is a surface-treated heat-expandable microsphere, a polymer component capable of being used as a base polymer of the pressure-sensitive adhesive, and / or The thermally exfoliable pressure-sensitive adhesive sheet which is a thermally expandable microsphere surface-treated with a tackifier component, a polymer component containing a functional group that can be used as a base polymer of the adhesive, The heat-peelable pressure-sensitive adhesive sheet, which is a thermally expandable microsphere surface-treated with a tackifier component containing a functional group, is also described.

  Since the heat-peelable pressure-sensitive adhesive sheet of the present invention has the above-described configuration, it is possible to reduce contamination of the adherend after peeling by heat treatment.

  Embodiments of the present invention will be described below in detail with reference to the drawings as necessary. In addition, the same code | symbol may be attached | subjected to the same member, a part, etc.

  The heat-peelable pressure-sensitive adhesive sheet of the present invention has at least a base material and a pressure-sensitive adhesive layer (heat-expandable pressure-sensitive adhesive layer) formed on at least one surface of the base material and containing thermally expandable microspheres. In addition, the heat-expandable microsphere is a surface-treated heat-expandable microsphere (sometimes referred to as “surface-treated heat-expandable microsphere”). Thus, in the heat-peelable pressure-sensitive adhesive sheet of the present invention, since the heat-expandable pressure-sensitive adhesive layer contains surface-treated heat-expandable microspheres, the surface of the heat-expandable microspheres and the adhesive component Throwing ability can be improved. Therefore, when the thermally expandable microspheres are expanded or expanded by heat treatment, cohesive failure of the adhesive component (particularly the base polymer) that covers the surface of the thermally expandable microsphere thinly in the thermally expandable adhesive layer. It can be effectively suppressed or prevented. Therefore, when the heat-peelable pressure-sensitive adhesive sheet is peeled off from the adherend, even if the heat-expandable pressure-sensitive adhesive layer is foamed or expanded by heat treatment, the adhesive component covering the surface of the heat-expandable microsphere is adhered. Transition to the body can be suppressed or prevented, and contamination of the adherend can be effectively reduced.

  FIG. 1 is a schematic sectional view partially showing an example of the heat-peelable pressure-sensitive adhesive sheet of the present invention. In FIG. 1, 1 is a heat-peelable pressure-sensitive adhesive sheet, 2 is a substrate, 3 is a rubber-like organic elastic layer, 4 is a heat-expandable pressure-sensitive adhesive layer, and 5 is a separator. A heat-peelable pressure-sensitive adhesive sheet 1 shown in FIG. 1 is formed on a base material 2, a rubber-like organic elastic layer 3 formed on one surface of the base material 2, and the rubber-like organic elastic layer 3. The heat-expandable pressure-sensitive adhesive layer 4 and a separator 5 formed on the heat-expandable pressure-sensitive adhesive layer 4 are further configured. The heat-expandable pressure-sensitive adhesive layer 4 in the heat-peelable pressure-sensitive adhesive sheet 1 contains surface-treated heat-expandable microspheres as heat-expandable microspheres.

[Heat-expandable adhesive layer]
It is important that the heat-expandable pressure-sensitive adhesive layer (heat-peelable pressure-sensitive adhesive layer) contains surface-treated heat-expandable microspheres. The heat-expandable pressure-sensitive adhesive layer expands or expands the surface-treated thermally expandable microspheres by heating, and can exhibit releasability by foaming or expanding the surface-treated thermally expandable microspheres. In addition, it is important that the heat-expandable pressure-sensitive adhesive layer contains surface-treated heat-expandable microspheres in such a content ratio that a predetermined peeling start temperature is exhibited. The surface-treated thermally expandable microspheres can be used alone or in combination of two or more.

  In the surface treatment type thermally expandable microsphere, the surface treatment agent for surface-treating the surface of the thermally expandable microsphere is not particularly limited as long as it can modify the surface of the thermally expandable microsphere. Although it is not, what can improve anchorage with the adhesive component (especially base polymer) in a thermally expansible adhesive layer can be used suitably. Therefore, the surface treatment agent can be appropriately selected according to the type of the pressure-sensitive adhesive component (base polymer or the like) in the thermally expandable pressure-sensitive adhesive layer.

  Specifically, examples of the surface treatment agent include a polymer component that can be used as a base polymer of an adhesive, a tackifier component, a plasticizer, and a coupling agent. In addition, a surface treating agent can be used individually or in combination of 2 or more types.

  More specifically, in the surface treatment agent, examples of the polymer component that can be used as the base polymer of the pressure-sensitive adhesive include acrylic polymers, rubber components, silicone polymers, vinyl alkyl ether polymers, polyester polymers, Examples include polyamide polymers, urethane polymers, and fluorine polymers. These polymer components include various adhesives (acrylic adhesives, rubber adhesives, silicone adhesives, vinyl alkyl ether adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives). The same polymer component as the base polymer in the pressure-sensitive adhesive or the like) can be used. Specifically, for example, as an acrylic polymer and a rubber component, an acrylic polymer exemplified as a base polymer in the acrylic pressure-sensitive adhesive and rubber pressure-sensitive adhesive as the pressure-sensitive adhesive in the thermally expandable pressure-sensitive adhesive layer [( An acrylic polymer (homopolymer or copolymer) using a meta) acrylic acid alkyl ester as a monomer component] or a rubber component (natural rubber or various synthetic rubbers).

  Examples of the tackifier component include rosin resins, petroleum resins, terpene resins, phenol resins, epoxy resins, polyamide resins, ketone resins, and elastomer resins. Examples of rosin resins include unmodified rosins (raw rosins) such as gum rosin, wood rosin, tall oil rosin, and modified rosins (polymerized rosins) modified by polymerization, disproportionation, hydrogenation, etc. Rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin, partially hydrogenated rosin, and other chemically modified rosins), and various rosin derivatives. Examples of the rosin derivative include a rosin phenolic resin obtained by adding phenol to an rosin (unmodified rosin, modified rosin, various rosin derivatives, etc.) with an acid catalyst and thermally polymerizing the rosin derivative; Ester compound of rosin esterified by the above (unmodified rosin ester), modified rosin esterified with alcohols such as polymerized rosin, stabilized rosin, disproportionated rosin, fully hydrogenated rosin, partially hydrogenated rosin Rosin ester resins such as ester compounds (polymerized rosin ester, stabilized rosin ester, disproportionated rosin ester, fully hydrogenated rosin ester, partially hydrogenated rosin ester, etc.); unmodified rosin and modified rosin (polymerized rosin, stable Rosin, disproportionated rosin, fully hydrogenated rosin, partially hydrogenated rosin) Unsaturated fatty acid modified rosin resin modified with unsaturated fatty acid; Unsaturated fatty acid modified rosin ester resin modified with unsaturated fatty acid from rosin ester resin; Unmodified rosin, modified rosin (polymerized rosin, stabilized rosin, disproportionate) Rosin, fully hydrogenated rosin, partially hydrogenated rosin), unsaturated fatty acid-modified rosin resins and unsaturated fatty acid-modified rosin ester resins, rosin alcohol resins obtained by reducing carboxyl groups; unmodified rosins, modified rosins, And metal salts of rosin resins (particularly, rosin ester resins) such as various rosin derivatives. Examples of petroleum resins include aromatic petroleum resins, aliphatic petroleum resins, alicyclic petroleum resins (aliphatic cyclic petroleum resins), aliphatic / aromatic petroleum resins, aliphatic / alicyclic resins. Known petroleum resins such as petroleum resins, hydrogenated petroleum resins, coumarone resins, coumarone indene resins and the like can be mentioned. Examples of the terpene resins include α-pinene polymers, β-pinene polymers, dipentene polymers, and modified terpene resins (phenol modified, aromatic modified, hydrogenated modified, hydrocarbon modified, etc.). Modified terpene resins (for example, terpene phenol resins, styrene modified terpene resins, aromatic modified terpene resins, hydrogenated terpene resins, etc.). Examples of phenolic resins include condensates of various phenols (eg, phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin, etc.) and formaldehyde (eg, alkylphenolic resins, xyleneformaldehyde resins). And the like, and resols obtained by addition reaction of the phenols and formaldehyde with an alkali catalyst, and novolaks obtained by condensation reaction of the phenols and formaldehyde with an acid catalyst.

  Further, examples of the plasticizer include phthalic acid plasticizers (for example, dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, ditridecyl phthalate, ditriisodecyl phthalate, butyl lauryl phthalate, Butyl benzyl phthalate), trimellitic acid plasticizers (eg, trioctyl trimellitic acid, tri-n-octyl trimellitate, etc.), fatty acid plasticizers (eg, tributyl citrate, dioctyl adipate, dioctyl azelate) , Dioctyl sebacate, methyl acetyl lysylate, etc.), phosphoric acid plasticizers (for example, tricresyl phosphate, trioctyl phosphate, etc.), epoxy plasticizers, polyester plasticizers and the like.

  Furthermore, examples of the coupling agent include a silane coupling agent, an organic titanium coupling agent, and an organic phosphorus coupling agent.

  In the present invention, as the surface treatment agent, a polymer component (particularly, a polymer component that can be used as a base polymer of an adhesive) or a tackifier component can be suitably used. As the polymer component that can be used as the base polymer of the pressure-sensitive adhesive, an acrylic polymer is suitable, and as the tackifier component, a rosin resin is suitable.

  In such a surface treatment agent, a polymer component containing a functional group or a tackifying component containing a functional group is preferable as the polymer component or the tackifying component. By using a component containing a functional group (such as a polymer component containing a functional group or a tackifier component containing a functional group) as a surface treatment agent, intermolecular force works between the base polymer of the adhesive. There is an effect that the anchoring property between the thermally expandable microspheres and the adhesive component is increased. Moreover, when the base polymer of an adhesive has a reactive group or when a reactive substance is added to the adhesive, the anchoring property between the thermally expandable microsphere and the adhesive component is increased by reacting with them. The effect is played. As a functional group which a polymer component contains, a carboxyl group, a hydroxyl group, an epoxy group, an amino group, a cyano group, a sulfonic acid group etc. are mentioned, for example, A carboxyl group and a hydroxyl group are suitable. In addition, the polymer component may contain only 1 type of functional group, and may contain 2 or more types of functional groups. As a method for introducing a functional group into a molecule of a polymer component, for example, a method of copolymerization using a monomer component containing a functional group, a method of reacting a compound containing a functional group with a polymer, or the like is used. Can do.

  Specifically, examples of the polymer component containing a functional group include functional groups such as an acrylic polymer containing a carboxyl group, an acrylic polymer containing a hydroxyl group, and an acrylic polymer containing an epoxy group. An acrylic polymer etc. are mentioned.

  The surface treatment method for the heat-expandable microspheres is not particularly limited. For example, the heat-expandable microspheres are introduced (injected) into a solution such as a solution containing the surface treatment agent or a melt of the surface treatment agent. After that, the thermally expandable microspheres are taken out from the liquid using a known separation means (for example, a separation means by filtration, etc.) and dried or cured as necessary. Examples of the method include applying a surface treatment agent to the surface using a known application method, and performing drying and curing as necessary.

  In addition, in the solution containing a surface treating agent, it does not restrict | limit especially as a solvent used in order to dissolve a surface treating agent, According to the kind etc. of surface treating agent, it can select suitably. Specifically, examples of the solvent include aromatic hydrocarbon solvents such as toluene, benzene, and xylene; alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; aliphatic hydrocarbon solvents such as hexane and heptane. And alcohols such as methanol and propanol.

  Further, the concentration of the surface treatment agent in the solution containing the surface treatment agent is not particularly limited, and can be appropriately set according to the kind of the surface treatment agent and the solvent, the thickness of the surface treatment agent layer, the drying time, and the like. .

  By such surface treatment, a surface treatment layer is formed on the surface of the thermally expandable microsphere, but the thickness of the surface treatment layer is not particularly limited, and may be a surface treatment layer at a monomolecular level, It can be selected from the range of several angstroms to several micrometers. However, since the average particle size of the heat-expandable microspheres is usually 100 μm or less (preferably 1 to 30 μm), if it is too thick, the heat-expandability and the pressure-sensitive adhesive properties of the pressure-sensitive adhesive sheet are affected. It is important to select an appropriate surface treatment layer thickness for the average particle size of the expandable microspheres and the thickness of the pressure-sensitive adhesive layer.

  In the present invention, the heat-expandable microspheres before surface treatment (sometimes simply referred to as “heat-expandable microspheres”) are not particularly limited, and known heat-expandable microspheres (various inorganic types). Thermally expandable microspheres, organic thermally expandable microspheres, etc.) can be selected as appropriate. As the thermally expandable microspheres, a microencapsulated foaming agent can be suitably used from the viewpoint of easy mixing operation. Examples of such thermally expandable microspheres include microspheres in which a material (thermally expandable material) that is easily gasified and expanded by heating, such as isobutane, propane, or pentane, is encapsulated in an elastic shell. Is mentioned. The shell is often formed of a hot-melt material or a material that is destroyed by thermal expansion. Examples of the substance forming the shell include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone. Thermally expandable microspheres can be produced by a conventional method such as a coacervation method or an interfacial polymerization method. Examples of thermally expandable microspheres include commercial products such as “Matsumoto Microsphere” (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.).

  In the thermally expandable microspheres, the separation start temperature to be applied is the type of the thermally expandable substance (particularly the vaporization temperature), the type of substance forming the shell, the thickness of the shell, and the particle diameter of the thermally expandable microsphere. The temperature can be adjusted to an appropriate temperature.

  As the heat-expandable microsphere, in order to reduce the adhesive force of the heat-expandable adhesive layer efficiently and stably by heat treatment, the volume expansion coefficient is 5 times or more, especially 7 times or more, particularly 10 times or more. Thermally expandable microspheres having an appropriate strength that does not rupture until they are preferred.

  In the heat-expandable pressure-sensitive adhesive layer, the content ratio (blending amount) of the surface-treated heat-expandable microspheres can be appropriately set according to the expansion ratio of the heat-expandable pressure-sensitive adhesive layer, the adhesive strength reduction property, and the like. However, for example, from the range of 1 to 150 parts by weight (preferably 10 to 130 parts by weight, more preferably 25 to 100 parts by weight) with respect to 100 parts by weight of the base polymer of the pressure-sensitive adhesive forming the thermally expandable pressure-sensitive adhesive layer. You can choose.

  The particle diameter (average particle diameter) of the surface-treated thermally expandable microspheres can be appropriately selected according to the thickness of the thermally expandable adhesive layer. The average particle diameter of the thermally expandable microspheres before the surface treatment can be selected from a range of, for example, 100 μm or less (preferably 80 μm or less, more preferably 1 to 50 μm, particularly 1 to 30 μm).

  Since the heat-expandable pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer, it is important to contain at least a pressure-sensitive adhesive for imparting adhesiveness together with the surface-treated heat-expandable microspheres for imparting thermal expandability. is there. As such a pressure-sensitive adhesive (pressure-sensitive adhesive), a pressure-sensitive adhesive that allows foaming and / or expansion of the surface-treated thermally expandable microspheres when the thermally expandable pressure-sensitive adhesive layer is heated can be used. Those which do not restrain the foaming and / or expansion of the treated thermally expandable microspheres as much as possible are preferable. An adhesive can be used individually or in combination of 2 or more types.

  The pressure-sensitive adhesive can be appropriately selected from known pressure-sensitive adhesives, and examples thereof include rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, and polyamides. Known adhesives such as adhesives based on urethane, urethane, and fluorine, and adhesives with improved creep characteristics in which these adhesives are blended with a hot-melt resin having a melting point of about 200 ° C. or less (For example, see JP-A-56-61468, JP-A-61-174857, JP-A-63-17981, JP-A-56-13040, etc.). These pressure-sensitive adhesives can be used alone or in combination of two or more. In addition to the polymer component such as an adhesive component (base polymer), the adhesive is a cross-linking agent (for example, polyisocyanate, alkyl etherified melamine compound, etc.), a tackifier, depending on the type of the adhesive. (For example, rosin derivative resin, polyterpene resin, petroleum resin, phenol resin, etc., which are solid, semi-solid or liquid at room temperature), and may contain appropriate additives such as plasticizer, filler, anti-aging agent, etc. Good. The pressure-sensitive adhesive may be any form of pressure-sensitive adhesive such as an emulsion-based pressure-sensitive adhesive or a solvent-based pressure-sensitive adhesive.

  As the pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive or an acrylic pressure-sensitive adhesive is preferable, and an acrylic pressure-sensitive adhesive can be particularly preferably used.

  Rubber adhesives include natural rubber and various synthetic rubbers [for example, polyisoprene rubber, styrene / butadiene block copolymer (SB) rubber, styrene / isoprene block copolymer (SI) rubber, styrene / isoprene / styrene. Block copolymer (SIS) rubber, styrene / butadiene / styrene block copolymer (SBS) rubber, styrene / isoprene / butadiene / styrene block copolymer (SIBS) rubber, styrene / ethylene / butylene / styrene block copolymer (SEBS) rubber, styrene / ethylene / propylene / styrene block copolymer (SEPS) rubber, styrene / ethylene / propylene block copolymer (SEP) rubber, recycled rubber, butyl rubber, polyisobutylene, and modified products thereof As the base polymer They include rubber-based adhesives.

The acrylic pressure-sensitive adhesive is an acrylic polymer [homopolymer (homopolymer) or copolymer (copolymer)] using one or more (meth) acrylic acid alkyl esters as monomer components. ] As the base polymer. Examples of the (meth) acrylic acid alkyl ester in the acrylic pressure-sensitive adhesive include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and (meth) acrylic. Butyl acid, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, ( Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, Undecyl (meth) acrylate, dodecyl (meth) acrylate, (meta Tridecyl acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, (meth) acrylic Examples include (meth) acrylic acid C _1-20 alkyl ester [preferably (meth) acrylic acid C _4-18 alkyl (linear or branched alkyl) ester] such as eicosyl acid.

  The acrylic polymer may be mixed with other monomer components copolymerizable with the (meth) acrylic acid alkyl ester as necessary for the purpose of modifying cohesion, heat resistance, crosslinkability, and the like. Corresponding units may be included. Examples of such monomer components include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and carboxyethyl acrylate; acid anhydrides such as maleic anhydride and itaconic anhydride Physical group-containing monomers; hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (N-substituted or unsubstituted) amide monomers such as N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; vinyl ester monomers such as vinyl acetate and vinyl propionate Styling Styrene monomers such as α-methylstyrene; vinyl ether monomers such as vinyl methyl ether and vinyl ethyl ether; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate Olefin or diene monomer such as ethylene, propylene, isoprene, butadiene and isobutylene; aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, etc. (Substituted or unsubstituted) amino group-containing monomers; (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl; N-vinylpyrrolidone, N -Methyl vinyl pyrrolidone, N-vinyl pyridine, N-vinyl piperidone, N-vinyl pyrimidine, N-vinyl piperazine, N-vinyl pyrazine, N-vinyl pyrrole, N-vinyl imidazole, N-vinyl oxazole, N-vinyl morpholine, N -Monomers having a nitrogen atom-containing ring such as vinyl caprolactam; N-vinylcarboxylic acid amides; Monomers containing sulfonic acid groups such as styrene sulfonic acid, allyl sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate A phosphate group-containing monomer such as 2-hydroxyethylacryloyl phosphate; a maleimide monomer such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; N Itacimide monomers such as methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide; N- ( Succinimide monomers such as (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide; polyethylene glycol (meth) acrylate, (meta ) Glycol acrylic ester monomers such as polypropylene glycol acrylate; Monomers having an oxygen atom-containing heterocycle such as tetrahydrofurfuryl (meth) acrylate; Fluorine Acrylic acid ester monomer containing fluorine atom such as (meth) acrylate; Acrylic acid ester monomer containing silicon atom such as silicone (meth) acrylate; 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, urethane acrylate, divinylbenzene, butyl di (meth) acrylate, hexyl And polyfunctional monomers such as di (meth) acrylate. These monomer components can be used alone or in combination of two or more.

  The heat-expandable pressure-sensitive adhesive layer is, for example, a conventional method of forming a sheet-like layer by mixing a pressure-sensitive adhesive, surface-treated heat-expandable microspheres, and, if necessary, a solvent or other additives. Can be formed. Specifically, for example, a mixture containing a pressure-sensitive adhesive, surface-treated thermally expandable microspheres, and, if necessary, a solvent and other additives is applied onto a base material or a rubber-like organic elastic layer described later. By applying the mixture on a suitable separator (such as release paper) to form a thermally expandable adhesive layer and transferring (transferring) it onto a base material or a rubbery organic elastic layer. An expandable adhesive layer can be formed. The thermally expandable pressure-sensitive adhesive layer may be either a single layer or multiple layers.

  The thickness of the heat-expandable pressure-sensitive adhesive layer can be appropriately selected depending on, for example, a reduction in adhesive force, and can be selected from a range of 500 μm or less, preferably 300 μm or less (more preferably 100 μm or less). is there. If the heat-expandable pressure-sensitive adhesive layer is too thick (excessive), the expansion of the heat-expandable pressure-sensitive adhesive layer is likely to occur after expansion or foaming by heat treatment. In some cases, adhesive residue (residue of adhesive component) that causes contamination may occur. On the other hand, if the thickness of the heat-expandable pressure-sensitive adhesive layer is too thin (too small), the degree of deformation of the heat-expandable pressure-sensitive adhesive layer due to heat treatment is small, the adhesive force is not easily lowered, and the surface to be added It is necessary to make the particle size of the process-type thermally expandable microspheres excessively small. Therefore, the thickness of the thermally expandable pressure-sensitive adhesive layer is preferably 5 μm or more (preferably 10 μm or more, more preferably 15 μm or more). Of course, it is important that the thickness of the heat-expandable pressure-sensitive adhesive layer is thicker than the maximum particle diameter of the surface-treated heat-expandable microspheres contained therein.

[Base material]
The substrate can be used as a support matrix such as a thermally expandable adhesive layer. In addition, the base material may have any form of the form of a single layer or the laminated form.

  Examples of the base material include paper base materials such as paper; fiber base materials such as cloth, non-woven fabric, felt, and net; metal base materials such as metal foil and metal plate; plastic base materials such as plastic films and sheets. Base materials: Rubber base materials such as rubber sheets; Foams such as foam sheets, and laminates thereof [particularly, laminates of plastic base materials and other base materials, or plastic films (or sheets) An appropriate thin leaf body such as a laminate and the like] can be used. As a base material, what is excellent in the heat resistance which does not melt at the heat processing temperature of a thermally expansible adhesion layer is preferable from points, such as the handleability after a heating. As the substrate, a plastic substrate such as a plastic film or sheet can be suitably used. Examples of the material in such a plastic material include olefins containing α-olefin as a monomer component such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), and the like. Resin: Polyester such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); polyvinyl chloride (PVC); polyphenylene sulfide (PPS); polyamide (nylon), wholly aromatic polyamide (aramid) Amide resins such as polyether ether ketone (PEEK) and the like. These materials can be used alone or in combination of two or more.

  In addition, when a plastic-type base material is used as a base material, you may control deformability, such as elongation rate, by extending | stretching process etc.

  The thickness of the substrate can be appropriately selected according to the strength, flexibility, purpose of use, and the like. For example, it is generally 1000 μm or less (for example, 1 to 1000 μm), preferably 1 to 500 μm, more preferably 3 to 3 μm. Although it is 300 micrometers, Most preferably, it is about 5-250 micrometers, It is not limited to these.

  The surface of the substrate is chemically or physically treated by conventional surface treatments such as chromic acid treatment, ozone exposure, flame exposure, high piezoelectric impact exposure, ionizing radiation treatment, etc. in order to enhance the adhesion to the thermally expandable adhesive layer. An oxidation treatment or the like may be performed by a conventional method, or a coating treatment or the like by a primer may be performed. Moreover, in order to give peelability with a thermally expansible adhesive layer etc., the coating process by release agents, such as silicone resin and a fluorine resin, etc. may be given, for example.

  In the present invention, the heat-expandable adhesive layer can be provided on at least one surface (one surface or both surfaces) of the base material, and the base material can be embedded in the heat-expandable adhesive layer. .

[Separator]
In the present invention, a conventional release paper or the like can be used as the separator. The separator is used as a protective material for the heat-expandable pressure-sensitive adhesive layer, and is peeled off when the heat-peelable pressure-sensitive adhesive sheet is attached to an adherend. The separator is not necessarily provided.

  As the separator, for example, a substrate having a release layer such as a plastic film or paper surface-treated with a release agent such as silicone, long chain alkyl, fluorine, molybdenum sulfide; polytetrafluoroethylene, polychlorotrifluoro Low adhesion substrate made of fluorine-based polymer such as ethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, chlorofluoroethylene / vinylidene fluoride copolymer; olefin resin (for example, A low-adhesive substrate made of a nonpolar polymer such as polyethylene or polypropylene can be used. In addition, a separator can also be used as a base material for supporting a heat-expandable adhesive layer.

  The separator can be formed by a known or common method. Further, the thickness of the separator is not particularly limited.

[Middle layer]
In the present invention, one or more intermediate layers may be provided between the base material and the thermally expandable adhesive layer. Examples of the intermediate layer include a release agent coating layer for the purpose of imparting peelability and an undercoat coating layer for the purpose of improving adhesion. Examples of the intermediate layer other than the release agent coating layer and the undercoat coating layer include, for example, a layer for imparting good deformability, a layer for increasing the adhesion area to the adherend, and adhesion. From the layer for the purpose of improving the force, the layer for the purpose of following the surface shape of the adherend satisfactorily, the layer for the purpose of improving the process of reducing the adhesive strength by heating, and the adherend after heating And a layer for the purpose of improving the peelability.

  In particular, as a layer (intermediate layer) between the base material and the heat-expandable pressure-sensitive adhesive layer from the viewpoint of imparting deformability of the heat-peelable pressure-sensitive adhesive sheet and improving peelability after heating, for example, rubbery organic elasticity A layer can be provided. By providing a rubber-like organic elastic layer, the surface of the heat-peelable pressure-sensitive adhesive sheet (the surface of the heat-expandable pressure-sensitive adhesive layer) is changed to the surface shape of the adherend when the heat-peelable pressure-sensitive adhesive sheet is bonded to the adherend. The adhesion area can be increased by following it well, and when the heat-peelable pressure-sensitive adhesive sheet is heat-peeled from the adherend, the heat expansion of the heat-expandable pressure-sensitive adhesive layer is highly controlled (accurately). In addition, the thermally expandable pressure-sensitive adhesive layer can be preferentially expanded uniformly in the thickness direction. The rubber-like organic elastic layer is a layer provided as necessary, and is not necessarily provided.

  The rubbery organic elastic layer is preferably provided on the base-side surface of the thermally expandable adhesive layer in a form superimposed on the thermally expandable adhesive layer. In addition, it can provide also as layers other than the intermediate | middle layer between a base material and a thermally expansible adhesive layer. The rubbery organic elastic layer can be interposed on one side or both sides of the substrate.

  The rubbery organic elastic layer is preferably formed of natural rubber, synthetic rubber or synthetic resin having rubber elasticity, for example, having a D-type Sure D-type hardness based on ASTM D-2240 of 50 or less, particularly 40 or less.

  Examples of the synthetic rubber or the synthetic resin having rubber elasticity include nitrile-based, diene-based, and acrylic-based synthetic rubbers; polyolefin-based and polyester-based thermoplastic elastomers; ethylene-vinyl acetate copolymer, polyurethane, polybutadiene, and the like. And a synthetic resin having rubber elasticity such as soft polyvinyl chloride. Even if it is essentially a hard polymer such as polyvinyl chloride, rubber elasticity can be manifested in combination with compounding agents such as plasticizers and softeners. Such a composition can also be used as a constituent material of the rubbery organic elastic layer. Further, an adhesive substance such as an adhesive constituting the thermally expandable adhesive layer can be preferably used as a constituent material of the rubbery organic elastic layer.

  The rubber-like organic elastic layer is, for example, a method in which a coating liquid containing a rubber-like organic elastic layer forming material such as natural rubber, synthetic rubber or synthetic resin having rubber elasticity is applied on a substrate (coating method), the rubber A method of adhering a film made of a layered organic elastic layer forming material or a laminated film in which a layer made of the rubbery organic elastic layer forming material is previously formed on one or more thermally expandable pressure-sensitive adhesive layers (dry laminating method) ), A resin composition containing the constituent material of the substrate and a resin composition containing the rubber-like organic elastic layer forming material can be formed by a forming method such as a method (coextrusion method).

  The thickness of the rubbery organic elastic layer is generally 500 μm or less (for example, 1 to 500 μm), preferably 3 to 300 μm, and more preferably about 5 to 150 μm. The rubbery organic elastic layer may be a single layer or may be composed of two or more layers.

  The rubbery organic elastic layer may be formed of an adhesive substance mainly composed of natural rubber, synthetic rubber, or synthetic resin having rubber elasticity, and is formed of a foam film or the like mainly composed of such a component. May be. Foaming is a conventional method, for example, a method using mechanical stirring, a method using a reaction product gas, a method using a foaming agent, a method for removing soluble substances, a method using a spray, a method for forming a syntactic foam, It can be performed by a sintering method or the like.

[Other adhesive layers]
In the present invention, in the heat-peelable pressure-sensitive adhesive sheet, when the thermally expandable pressure-sensitive adhesive layer is formed only on one surface (one surface) of the base material, the other pressure-sensitive adhesive layer is formed on the other surface of the base material. May be. Using the other adhesive layer, it can be attached and supported on a support such as a support base. The pressure-sensitive adhesive for forming such another pressure-sensitive adhesive layer is not particularly limited, and pressure-sensitive adhesives exemplified as the pressure-sensitive adhesive used in the above-mentioned thermally expandable pressure-sensitive adhesive layer (for example, rubber-based pressure-sensitive adhesive, acrylic pressure-sensitive adhesive) Adhesives, silicone pressure-sensitive adhesives, vinyl alkyl ether pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, fluorine-based pressure-sensitive adhesives, creep property improving pressure-sensitive adhesives, etc.) An adhesive can be used. These pressure-sensitive adhesives can be used alone or in combination of two or more.

  In addition, as thickness of another adhesion layer, 500 micrometers or less (for example, 5-500 micrometers, Preferably it is 10-300 micrometers, More preferably, it is 15-100 micrometers) may be sufficient. In the formation of the other adhesive layer, the same method as that for the thermally expandable adhesive layer (for example, a method of coating on a base material, after coating on a separator to form an adhesive layer, this is applied to the base material. A transfer method) can be used. The other adhesive layer may be either a single layer or multiple layers.

  The heat-peelable pressure-sensitive adhesive sheet of the present invention can be produced by forming a heat-expandable pressure-sensitive adhesive layer on a substrate via another layer (such as a rubbery organic elastic layer) as necessary. The heat-peelable pressure-sensitive adhesive sheet may have a form having an adhesive face only on one side, or may have a form having adhesive faces on both sides. The heat-peelable pressure-sensitive adhesive sheet can have a form such as a sheet form or a tape form.

  In the heat-peelable pressure-sensitive adhesive sheet of the present invention, since the heat-expandable pressure-sensitive adhesive layer contains surface-treated heat-expandable microspheres, the heat-expandable pressure-sensitive adhesive layer is foamed or expanded by heat treatment to adhere When peeling from the substrate, contamination of the adherend can be effectively reduced. Therefore, the heat-peelable pressure-sensitive adhesive sheet of the present invention exhibits excellent adhesiveness in the laminating process and the cutting process when the adherend is attached to the heat-peelable pressure-sensitive adhesive sheet during processing of the adherend. The adherend can be fixed, and after processing, contamination of the adherend can be suppressed or prevented, and the processed product can be easily peeled off. Therefore, it can exhibit excellent adhesiveness for fixing during processing of the adherend, and when it is desired to release the adhesive state after achieving the adhesive purpose, the adhesive force is reduced by heating to reduce the adherend. , And can be easily peeled or separated while suppressing or preventing contamination.

  Thus, the heat-peelable pressure-sensitive adhesive sheet of the present invention can be suitably used as a heat-peelable pressure-sensitive adhesive sheet used when processing an adherend. That is, the heat-peelable pressure-sensitive adhesive sheet of the present invention can adhere an adherend (workpiece) with a strong adhesive force at the time of processing, for example, and can quickly release the adhesion state after processing. It can be suitably used for possible applications. When the heat-peelable pressure-sensitive adhesive sheet is used, the contamination of the adherend can be suppressed or prevented after processing, and can be easily and quickly peeled off, and the manufacturing workability can be greatly improved.

  In addition, as a processing method of such a to-be-adhered body, it can select arbitrarily, for example, cutting (polishing processing, dicing processing, etc.), electrode printing processing (pattern formation processing, etc.) to a green sheet, Examples of the processing include assembly processing, and other examples include processing in a lamination process, processing in a pressurizing process, and processing in a firing process.

  Then, after processing the adherend (especially after achieving the adhesion purpose or when it is desired to release the adhesive state), the foaming start temperature of the surface-treated thermally expandable microspheres in the thermally expandable adhesive layer Alternatively, by heating to a temperature higher than that, the adhesive strength is reduced, and the adherend subjected to the processing treatment is peeled or separated, and the adherend (processed product) subjected to the processing treatment is isolated. can do.

  The heat treatment for peeling or separating the heat-peelable pressure-sensitive adhesive sheet from the adherend (processed product) uses, for example, an appropriate heating means such as a hot plate, a hot air dryer, a near infrared lamp, or an air dryer. Can be done. The heating temperature may be equal to or higher than the thermal expansion start temperature (foaming start temperature) of the surface-treated thermally expandable microspheres in the thermally expandable pressure-sensitive adhesive layer, but the conditions for the heat treatment are the surface state of the adherend, It can be set as appropriate depending on the reduction in adhesion area depending on the type of surface-treated thermally expandable microspheres, the heat resistance of the substrate or adherend, the heating method (heat capacity, heating means, etc.), and the like. General heat treatment conditions are a temperature of 100 to 250 ° C. and a time of 5 to 90 seconds (hot plate or the like) or 5 to 15 minutes (hot air dryer or the like). Under such heating conditions, the surface-expandable thermally expandable microspheres in the thermally expandable pressure-sensitive adhesive layer generally expand and / or foam and the heat-expandable pressure-sensitive adhesive layer expands and deforms, resulting in uneven deformation and reduced adhesive strength. Or lost. Note that the heat treatment can be performed at an appropriate stage depending on the purpose of use. In some cases, an infrared lamp or heated water can be used as the heating source.

  Moreover, the heat-peelable pressure-sensitive adhesive sheet of the present invention can also be used as a protective material when the adherend is conveyed.

[Adherent]
In the present invention, an article (an adherend or a workpiece) to be adhered and held by the heat-peelable pressure-sensitive adhesive sheet can be arbitrarily selected. Specifically, the adherend (workpiece) includes electronic parts such as semiconductor wafers and semiconductor chips; electrical articles such as ceramic capacitors and oscillators; display devices such as liquid crystal cells, Various articles, such as a thermal head, a solar cell, and a printed circuit board, are mentioned. An adherend may be individual or may be combined 2 or more types.

[Processed adherend; Processed product]
Moreover, in this invention, after attaching a workpiece (workpiece) as a to-be-adhered body to a heat-peelable pressure-sensitive adhesive sheet, various processed products can be obtained by processing. For example, when an electronic component such as a semiconductor wafer is used as the adherend (processed product), an electronic component, a circuit board, or the like can be obtained as the processed product. Further, when a ceramic capacitor green sheet is used as the adherend, a multilayer ceramic capacitor or the like can be obtained as a processed product. That is, in the present invention, the electronic component and the multilayer ceramic capacitor are manufactured using the heat-peelable pressure-sensitive adhesive sheet, and are manufactured using the method for processing an adherend as described above.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
Prepare a methanol solution of rosin phenolic resin by dissolving rosin phenolic resin (trade name “Tamanor 135” manufactured by Arakawa Chemical Industries, Ltd.) as a tackifying component in methanol at a concentration of 2% by weight. did. In this methanol solution, the trade name “Matsumoto Microsphere F-501D” (manufactured by Matsumoto Yushi Seiyaku Co., Ltd .; 120 ° C. foaming type; sometimes referred to as “thermally expandable microsphere A”) as thermally expandable microspheres. After being charged, stirred with a stirrer, filtered, dried, and thermally expandable microspheres whose surface is coated with a rosin phenolic resin (sometimes referred to as “surface-treated thermally expandable microsphere B”). )

  Next, an acrylic copolymer (ethyl acrylate: 70 parts by weight, 2-ethylhexyl acrylate: 30 parts by weight, hydroxyethyl acrylate: 5 parts by weight, and methyl methacrylate: 5 parts by weight as an acrylic component) Copolymer): A toluene solution containing a pressure-sensitive adhesive having a structure in which 2 parts by weight of an isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.) is prepared with respect to 100 parts by weight. Then, the toluene solution is applied to one side of a polyester film (thickness: 100 μm) as a base material so that the thickness after drying or curing becomes 10 μm, and dried by heating at 120 ° C. for 2 minutes. Thus, a rubbery organic elastic layer was obtained.

  In addition, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2-ethylhexyl: 30 parts by weight, hydroxyethyl acrylate: 5 parts by weight, and methyl methacrylate: 5 parts by weight as an acrylic copolymer) Polymer): 100 parts by weight of isocyanate crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 2.5 parts by weight, surface-treated thermally expandable microspheres B: 30 parts by weight, and Tackifying resin (trade name “Tamanor 135” manufactured by Arakawa Chemical Industries, Ltd .; rosin phenol-based resin): A toluene solution containing a heat-expandable microsphere-containing pressure-sensitive adhesive having a composition containing 10 parts by weight was prepared. The toluene solution is applied on the separator so that the thickness after drying or curing is 30 μm, and is dried by heating at 70 ° C. for 3 minutes to obtain a thermal expansion. After obtaining the heat-sensitive adhesive layer, the heat-expandable pressure-sensitive adhesive layer is bonded to the rubber-like organic elastic layer, and heat peeling having a layer structure of “base material / rubber-like organic elastic layer / heat-expandable pressure-sensitive adhesive layer” A mold pressure-sensitive adhesive sheet (sometimes referred to as “thermally peelable pressure-sensitive adhesive sheet A”) was obtained. In addition, the heat-expandable pressure-sensitive adhesive layer in the heat-peelable pressure-sensitive adhesive sheet A contains surface-treated heat-expandable microspheres B.

(Example 2)
Acrylic copolymer (acrylic copolymer comprising 70 parts by weight of ethyl acrylate, 30 parts by weight of 2-ethylhexyl acrylate, 5 parts by weight of hydroxyethyl acrylate, and 5 parts by weight of methyl methacrylate as monomer components) ) Was dissolved in toluene at a concentration of 5% by weight to prepare a toluene solution of an acrylic copolymer. Into this toluene solution, thermally expandable microspheres A (trade name “Matsumoto Microsphere F-501D” (manufactured by Matsumoto Yushi Seiyaku Co., Ltd .; 120 ° C. foaming type) are added, stirred with a stirrer, and filtered. And dried to obtain thermally expandable microspheres whose surface was coated with an acrylic copolymer (sometimes referred to as “surface-treated thermally expandable microsphere C”).

  “Substrate / rubber-like organic elastic layer / thermal expansibility” in the same manner as in Example 1 except that the surface-treated thermally expansible microsphere B was used instead of the surface treated expansible microsphere B. A heat-peelable pressure-sensitive adhesive sheet having a layer configuration of “adhesive layer” (sometimes referred to as “heat-peelable pressure-sensitive adhesive sheet B”) was obtained.

  That is, a rubbery organic elastic layer was obtained in the same manner as in Example 1. In addition, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2-ethylhexyl: 30 parts by weight, hydroxyethyl acrylate: 5 parts by weight, and methyl methacrylate: 5 parts by weight as an acrylic copolymer) Polymer): 100 parts by weight of isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 2.5 parts by weight, surface-treated thermally expandable microspheres C: 30 parts by weight, and Tackifying resin (trade name “Tamanor 135” manufactured by Arakawa Chemical Industries, Ltd .; rosin phenol-based resin): A toluene solution containing a heat-expandable microsphere-containing pressure-sensitive adhesive having a composition containing 10 parts by weight was prepared. The toluene solution is applied on the separator so that the thickness after drying or curing is 30 μm, and is dried by heating at 70 ° C. for 3 minutes to obtain a thermal expansion. After obtaining sexual adhesive layer, the heat-expandable pressure-sensitive adhesive layer, bonded to the rubbery organic elastic layer to obtain a heat-peelable pressure-sensitive adhesive sheet B. In addition, the heat-expandable pressure-sensitive adhesive layer in the heat-peelable pressure-sensitive adhesive sheet B contains surface-treated heat-expandable microspheres C.

(Comparative Example 1)
Except that the surface treatment of the thermally expandable microsphere was not performed (that is, except that the thermally expandable microsphere A was used instead of the surface treatment type thermally expandable microsphere B), the same as in Example 1. Thus, a heat-peelable pressure-sensitive adhesive sheet (sometimes referred to as “heat-peelable pressure-sensitive adhesive sheet C”) having a layer configuration of “base material / rubber-like organic elastic layer / heat-expandable pressure-sensitive adhesive layer” was obtained.

  That is, a rubbery organic elastic layer was obtained in the same manner as in Example 1. In addition, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2-ethylhexyl: 30 parts by weight, hydroxyethyl acrylate: 5 parts by weight, and methyl methacrylate: 5 parts by weight as an acrylic copolymer) Polymer): 100 parts by weight, isocyanate crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 2.5 parts by weight, thermally expandable microspheres A: 30 parts by weight, and tackifying resin (Trade name “Tamanor 135” manufactured by Arakawa Chemical Industries, Ltd .; rosin phenolic resin): A toluene solution containing a heat-expandable microsphere-containing pressure-sensitive adhesive having a constitution in which 10 parts by weight is blended is prepared, and the toluene The solution is applied on the separator so that the thickness after drying or curing is 30 μm, and is heated and dried at 70 ° C. for 3 minutes to form a thermally expandable adhesive layer After obtaining, the heat-expandable pressure-sensitive adhesive layer, bonded to the rubbery organic elastic layer to obtain a heat-peelable pressure-sensitive adhesive sheet C. In addition, the heat-expandable pressure-sensitive adhesive layer in the heat-peelable pressure-sensitive adhesive sheet C contains heat-expandable microspheres A. The thermally expandable microsphere A is a thermally expandable microsphere that has not been surface-treated.

(Evaluation)
About each heat-peelable pressure-sensitive adhesive sheet obtained in Examples 1 and 2 and Comparative Example 1, adhesive strength and antifouling property were measured or evaluated by the following measurement method or evaluation method.

(Measurement method of adhesive strength)
2 kg of a 25 μm thick polyester film (trade name “Lumirror S-10”, manufactured by Toray Industries, Inc.) on the adhesive surface of each heat-peelable adhesive sheet (cut into a width of 20 mm) obtained in Examples and Comparative Examples. Adhering by reciprocating with a roller, with Shimadzu Autograph AGS-50D (manufactured by Shimadzu Corporation), peel adhesion (adhesive force) (N / 20 mm) (peeling angle: 180 °, tensile speed: 300 mm / min, temperature) : 23 ± 2 ° C., humidity: 65 ± 5% RH, peels polyester film).

  In addition, on the adhesive surface of each heat-peelable adhesive sheet (cut into a width of 20 mm) obtained in Examples and Comparative Examples, a 25 μm thick polyester film (trade name “Lumirror S-10” manufactured by Toray Industries, Inc.) After sticking with 1 kg of 2 kg roller, heat treatment is performed for 1 minute on a 130 ° C. hot plate, left at room temperature for 30 minutes, and then peel adhesion (adhesive strength) after heat treatment (N / 20 mm) ) (Peeling angle: 180 °, tensile speed: 300 mm / min, temperature: 23 ± 2 ° C., humidity: 65 ± 5% RH, peeling the polyester film).

  The evaluation results are shown in the “Adhesive strength (N / 20 mm)” column of Table 1 for the adhesive strength when heat treatment is not performed, and for the adhesive strength after the heat treatment, “ It is shown in the column of “Adhesive strength after heating (N / 20 mm)”.

(Evaluation method for pollution prevention)
Mirror of 4 inch silicon wafer (silicon wafer “CZ-N POLISHED WAFER (4 inch)” manufactured by Shin-Etsu Semiconductor Co., Ltd.) obtained by mirror-treating each heat-peelable adhesive sheet obtained in Examples and Comparative Examples in a clean room After being allowed to stand for 1 hour after being adhered to the surface, the number of particles having a particle diameter of 0.28 μm or more (pieces / 4 inch wafer) on the mirror surface of the silicon wafer when heated and peeled at 130 ° C. is measured with a laser surface inspection device “LS-5000”. [Measured by Hitachi Electronics Engineering Co., Ltd.] to evaluate the anti-contamination property. Of course, the smaller the number of particles, the better the anti-contamination property. The evaluation results are shown in the column of “Contamination prevention (pieces / 4 inches)” in Table 1.

  From Table 1, the heat-peelable pressure-sensitive adhesive sheets A and B according to Examples 1 and 2 have good adhesive strength, can be easily peeled off by heating, and are peeled off by heat treatment. It was confirmed that the surface of the kimono had excellent anti-staining properties. Therefore, as in Examples 1 and 2, by using surface-treated thermally expandable microspheres, a heat-peelable pressure-sensitive adhesive sheet that can reduce contamination of the adherend after peeling due to heat treatment is obtained. be able to.

It is a schematic sectional drawing which shows the example of the heat-peeling type adhesive sheet of this invention partially.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermally peelable adhesive sheet 2 Base material 3 Rubber-like organic elastic layer 4 Thermal expansion adhesive layer 5 Separator

Claims (2)

A heat-peelable pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer containing thermally expandable microspheres is provided on at least one surface of a substrate, and the thermally expandable microspheres can be used as a base polymer of the adhesive A heat-peelable pressure-sensitive adhesive sheet, which is a thermally expandable microsphere surface-treated with an acrylic polymer and / or a rosin resin . The heat-expandable microsphere is a heat-expandable microsphere surface-treated with an acrylic polymer containing a functional group that can be used as a base polymer of an adhesive and / or a rosin resin containing a functional group. The heat-peelable pressure-sensitive adhesive sheet according to claim 1.

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