JP5132064B2 - Heat-peelable adhesive sheet - Google Patents

Description

  The present invention relates to a heat-peelable pressure-sensitive adhesive sheet, and more specifically, heat-peeling that can be easily peeled off from an adherend by heat treatment at any time, even if the adhesiveness to the adherend is enhanced. It relates to an adhesive sheet.

  As a heat-peelable pressure-sensitive adhesive sheet in which the adhesive strength is reduced or lost by heat treatment, a pressure-sensitive adhesive sheet (single-sided pressure-sensitive adhesive sheet) provided with a thermally expandable pressure-sensitive adhesive layer on one side of a supporting base, A pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet) having a thermally expandable pressure-sensitive adhesive layer on one surface and a pressure-sensitive adhesive layer on the other surface is widely known (see, for example, Patent Documents 1 to 5). ).

  In recent years, as electronic parts and semiconductor devices have become more sophisticated and thinner, there have been a wide variety of device manufacturing methods. Among them, manufacturing methods using the heat-peelable pressure-sensitive adhesive sheet have been widely studied. It has come to be. For example, as an example of a manufacturing process of a ceramic capacitor, (1) an electrode printing process on a green sheet, (2) a lamination process, (3) a pressing process (pressing press process), (4) a cutting process, 5) There is a firing step, and the laminating step (2) and the pressurizing step (3) are repeated a predetermined number of times, and then the manufacturing step moves to the cutting step (4). In such a ceramic capacitor manufacturing process, the heat-peelable pressure-sensitive adhesive sheet firmly fixes the green sheet until the cutting process (4), and after the cutting process (4), the adhesive force is lost by heating and cutting. The used ceramic capacitor is used in the form of peeling from the sheet piece. In recent years, miniaturization of semiconductor chips has progressed, and during cutting, particularly in dicing, there has been a problem that the semiconductor chips that have been miniaturized are likely to scatter due to vibrations of the dicing blade, and higher adhesive strength is required than before. It has come to be.

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, in the heat-peelable pressure-sensitive adhesive sheet having a conventional layer structure, if the pressure-sensitive adhesive layer is simply increased in the pressure-sensitive adhesive layer, the pressure-sensitive adhesiveness is not sufficiently lowered after the heat treatment, and a satisfactory peeling effect is not exhibited. The problem that occurred. Therefore, as a heat-peelable pressure-sensitive adhesive sheet, it is possible to increase the adhesion to the adherend and firmly fix the adherend, and even when the adhesion to the adherend is enhanced, There is a need for a heat-peelable pressure-sensitive adhesive sheet that can be easily peeled off from an adherend by heat treatment.

Accordingly, an object of the present invention is to provide a heat-peelable pressure-sensitive adhesive sheet that can be easily peeled off from an adherend by heat treatment at any time, even if the adhesion to the adherend is enhanced. is there.
Another object of the present invention is to provide a heating that can increase the adhesiveness to the adherend and sufficiently reduce the adhesiveness due to the heat treatment even if the adhesive force of the thermally expandable adhesive layer itself is the same. It is in providing a peelable adhesive sheet.

  As a result of intensive studies to achieve the above object, the present inventors have found that when a heat-expandable pressure-sensitive adhesive layer in a heat-peelable pressure-sensitive adhesive sheet is formed on a non-porous substrate via a specific layer, a heat-expandable pressure-sensitive adhesive layer is formed. It has been found that even when the adhesive strength of the layer is large, the heat-peelable pressure-sensitive adhesive sheet can be easily peeled off from the adherend by heat treatment at any time. The present invention has been completed based on these findings.

That is, the present invention
A heat-peelable pressure-sensitive adhesive sheet in which a thermally expandable pressure-sensitive adhesive layer containing a foaming agent is formed on at least one surface of a non-porous substrate,
Between the non-porous substrate and the thermally expandable adhesive layer formed on at least one surface of the non-porous substrate has a porous material layer having a porosity of 10% or more,
Provided is a heat-peelable pressure-sensitive adhesive sheet comprising a rubbery organic elastic layer between a non-porous substrate and a porous material layer.
In the heat-peelable pressure-sensitive adhesive sheet, the porous material layer is preferably a nonwoven layer.

In the heat-peelable pressure-sensitive adhesive sheet, the non-porous substrate is preferably a polyester film or a sheet.
In the heat-peelable pressure-sensitive adhesive sheet, the thickness of the porous material layer is preferably 5 to 250 μm.
The heat-peelable pressure-sensitive adhesive sheet has a rubbery organic elastic layer between the non-porous substrate and the porous material layer and / or between the porous material layer and the thermally expandable pressure-sensitive adhesive layer. Preferably it is.
The heat-peelable pressure-sensitive adhesive sheet is preferably used for fixing electronic parts when processing the electronic parts.

In this specification, in addition to the above invention,
A heat-peelable pressure-sensitive adhesive sheet in which a thermally expandable pressure-sensitive adhesive layer containing a foaming agent is formed on at least one surface of a non-porous substrate, wherein the non-porous substrate and at least one of the non-porous substrate A heat-peelable pressure-sensitive adhesive sheet having a porous material layer between the heat-expandable pressure-sensitive adhesive layer formed on the surface is also described.

  According to the heat-peelable pressure-sensitive adhesive sheet of the present invention, even if the adhesion to an adherend is enhanced, it can be easily peeled off from the adherend by heat treatment at any time. Further, even if the adhesive force of the thermally expandable adhesive layer itself is the same, it is possible to increase the adhesiveness to the adherend and sufficiently reduce the adhesiveness due to the 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.
[Heat-release adhesive sheet]
As shown in FIGS. 1A to 1B, the heat-peelable pressure-sensitive adhesive sheet of the present invention comprises a non-porous substrate and a foaming agent formed on at least one surface of the non-porous substrate. A porous material between the non-porous substrate and the thermally expandable pressure-sensitive adhesive layer formed on at least one surface of the non-porous substrate. Has a layer. Fig.1 (a)-(b) is a schematic sectional drawing which shows partially an example of the heat-peelable adhesive sheet of this invention. 1A to 1B, 1a and 1b are heat-peelable pressure-sensitive adhesive sheets, 2 is a non-porous substrate (non-porous support substrate), 3 is a porous material layer, and 4 is a rubbery organic elastic material. Layers 5 and 5 are thermally expandable adhesive layers, and 6 is a separator (release liner). The heat-peelable pressure-sensitive adhesive sheet 1a shown in FIG. 1 (a) has a configuration in which a porous material layer 3 and a heat-expandable pressure-sensitive adhesive layer 5 are formed in this order on one side of a non-porous substrate 2. The thermally expandable pressure-sensitive adhesive layer 5 has a form protected by a separator 6. In addition, the heat-peelable pressure-sensitive adhesive sheet 1b shown in FIG. 1B has a porous material layer 3, a rubber-like organic elastic layer 4, and a heat-expandable pressure-sensitive adhesive layer 5 in this order on one side of the non-porous substrate 2. The thermally expandable pressure-sensitive adhesive layer 5 has a form protected by a separator 6.

  Thus, the heat-peelable pressure-sensitive adhesive sheet of the present invention has a configuration in which the heat-expandable pressure-sensitive adhesive layer is formed on the non-porous substrate via the porous material layer, and the porous material layer However, since the adherend bonded onto the thermally expandable adhesive layer can absorb and relieve stress when it is peeled off from the thermally expandable adhesive layer, it is stronger against the adherend. Can exhibit excellent adhesiveness. That is, in the present invention, the adhesiveness of the thermally expandable adhesive layer itself is not increased, but the thermally expandable adhesive layer is formed on the non-porous substrate via the porous material layer. Even if the adhesive force by the expandable adhesive layer itself is the same, the adherence to the adherend as the whole heat-peelable adhesive sheet can be increased, and the adherend bonded onto the thermally expandable adhesive layer Can be firmly fixed. The stress that causes the adherend bonded to the heat-expandable pressure-sensitive adhesive sheet on the heat-expandable pressure-sensitive adhesive layer to be peeled off from the heat-expandable pressure-sensitive adhesive layer is not particularly limited. And stress due to vibration of a blade (such as a dicing blade) used in the cutting step of cutting.

  In addition, when the adherend bonded to the thermally expandable adhesive layer is peeled off, the adhesiveness can be sufficiently lowered by subjecting the thermally expandable adhesive layer to a heat treatment. That is, in the present invention, since the composition and adhesive strength of the thermally expandable adhesive layer are not controlled, the peeling function of the thermally expandable adhesive layer itself by the heat treatment is effectively exhibited, and the adhesiveness is reduced by the heat treatment. The adherend can be easily peeled off from the thermally expandable adhesive layer by heat treatment.

  Therefore, the heat-peelable pressure-sensitive adhesive sheet can be easily peeled from the adherend by heat treatment at any time, even if the adhesiveness to the adherend is enhanced. That is, the heat-peelable pressure-sensitive adhesive sheet can achieve both stronger pressure-sensitive adhesiveness and easy peelability.

[Porous material layer]
The porous material layer (porous material layer) is a layer provided between the non-porous substrate and the thermally expandable adhesive layer (not used as a support) and has porosity. ing. The porous material layer is not particularly limited as long as it is a porous layer. The pores (bubbles) in the porous material layer may be formed continuously or independently (individually). That is, the porous material layer may have bubbles in any form of open cells, closed cells, or a combination of these. In the porous material layer, the porosity (bubble ratio) is not particularly limited, but is, for example, 10% or more (preferably 40% or more, more preferably 70% or more). When the porosity of the porous material layer is less than 10%, the porous material layer relieves stress when the adherend bonded to the thermally expandable adhesive layer is peeled off from the thermally expandable adhesive layer. However, the effect of increasing the adhesiveness by the adhesive surface on the side of the thermally expandable adhesive layer formed on the porous material layer is reduced. In the present invention, the method for obtaining the porosity of the porous material layer is not particularly limited, and may be any method such as a method of calculating from the density, a method of calculating by gas injection, or a method of calculating from the air permeability. However, a method of calculating from the density is preferable.

  The porosity value is a value calculated from the density of the porous material layer. As a method for calculating the porosity of the porous material layer from the density, specifically, it is defined by the following expression “porosity (P) = [(true density) − (bulk density)] / (true density)”. it can. The bulk density is calculated from “volume density” = (weight) / (volume) ”by determining volume and weight. The true density is measured according to, for example, JIS R-7212.

  More specifically, examples of the porous material layer include a fiber-based porous material layer formed using a fiber material, a resin-based porous material layer formed by forming bubbles using a resin material, and a paper material. And a paper-based porous material layer formed using The porous material layer may have a single layer structure or a multilayer structure.

  The fiber-based porous material layer is not particularly limited as long as it is a porous layer formed using a fiber material, and examples thereof include a cloth (woven fabric) layer and a nonwoven fabric layer, and a nonwoven fabric layer is preferable. It is. Moreover, it does not restrict | limit especially as a fiber material used in a fiber type porous material layer, Any of a natural fiber, a semisynthetic fiber, and a synthetic fiber may be sufficient. Examples of the fiber material include cotton fiber, rayon fiber, polyamide fiber, polyester fiber (polyethylene terephthalate fiber, etc.), polyacrylonitrile fiber, acrylic fiber, polyvinyl alcohol fiber, polyolefin fiber (polyethylene fiber and polypropylene). Etc.), polyimide fibers, polyurethane fibers, carbon fibers (carbon fibers), silicone fibers, fluorine fibers and the like. The fiber material may be used independently and 2 or more types may be used in combination.

  The resin-based porous material layer is not particularly limited as long as it is a porous layer (such as a foam layer) formed by bubble formation (such as foaming) using a resin material. The resin-based porous material layer may have a configuration in which a porous body (such as a foam) is dispersed in the resin. Moreover, it does not restrict | limit especially as a resin material used in a resin type porous material layer, For example, polyolefin-type resin (Polyethylene, a polypropylene, an ethylene-propylene copolymer, ethylene-vinyl acetate copolymer etc.), polyester type Examples thereof include resins (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polybutylene naphthalate, etc.), polyimides, acrylic resins, urethane resins, acrylic-urethane copolymers, vinyl acetate resins, polyvinyl chloride, and the like. The resin material may be used independently and 2 or more types may be used in combination.

  In the resin-based porous material layer, the bubble forming method for forming bubbles using a resin material is a known bubble forming method, for example, a bubble forming method by mechanical stirring, or bubble formation using a reaction product gas. Method, bubble formation method using foaming agent (foaming method), bubble formation method to remove soluble substances, bubble formation method by spraying, bubble formation method to form syntactic foam, bubble formation method by sintering, etc. A foaming method is preferred. Therefore, a foam layer is suitable as the resin-based porous material layer. A foaming agent can be used when the resin-based porous material layer is formed by a foaming method. The foaming agent can be appropriately selected from known foaming agents, and examples thereof include thermally expandable microspheres, other organic foaming agents, and inorganic foaming agents. Specific examples of these foaming agents include the foaming agents specifically exemplified in the section of the thermally expandable pressure-sensitive adhesive layer.

  In the resin-based porous material layer, the resin material may be cross-linked. A crosslinking agent can be used for crosslinking the resin material. As a crosslinking agent, it can select suitably according to the kind of resin material etc., For example, urea type crosslinking agent besides an isocyanate type crosslinking agent, an epoxy type crosslinking agent, a melamine type crosslinking agent, a peroxide type crosslinking agent , Metal alkoxide crosslinkers, metal chelate crosslinkers, metal salt crosslinkers, carbodiimide crosslinkers, oxazoline crosslinkers, aziridine crosslinkers, amine crosslinkers, and the like. Specific examples of the crosslinking agent include the crosslinking agents specifically exemplified in the section of the thermally expandable pressure-sensitive adhesive layer.

  The paper-based porous material layer is not particularly limited as long as it is a porous layer formed using a paper material. Examples of the paper material used in the paper-based porous material layer include Japanese paper material, western paper material, high-quality paper material, glassine paper material, kraft paper material, kulpack paper material, crepe paper material, and the like. The paper material may be used independently and 2 or more types may be used in combination.

  As the porous material layer, a fiber-based porous material layer (nonwoven fabric layer, etc.) formed using a fiber material, and a resin-based porous material layer (foam layer, etc.) formed by forming bubbles using a resin material Of these, a fibrous porous material layer (particularly a nonwoven fabric layer) is preferred.

  The thickness of the porous material layer is not particularly limited, and can be appropriately selected according to the type of the porous material layer, for example, 5 to 250 μm (preferably 10 to 200 μm, more preferably 20 to 100 μm). ) Can be selected appropriately. When the thickness of the porous material layer is less than 5 μm, the adherend bonded onto the thermally expandable adhesive layer is thermally expanded as in the case where the porosity of the porous material layer is less than 10%. The stress that peels off the porous adhesive layer is not sufficiently relaxed, and the adhesiveness of the adhesive surface on the thermally expandable adhesive layer formed on the porous material layer is increased. The effect is reduced.

  As a formation method of a porous material layer, it can select suitably from well-known formation methods according to the kind etc. of a porous material layer. For example, when the porous material layer is a fiber-based porous material layer or a paper-based porous material layer, it is formed by laminating cloth, nonwoven fabric, paper, etc. on a predetermined surface such as a non-porous substrate surface can do. When the porous material layer is a resin-based porous material layer and the resin-based porous material layer is formed by foaming using a resin material, a foaming agent is formed on a predetermined surface such as a non-porous substrate surface. It can be formed by applying a resin material composition containing, foaming a foaming agent after crosslinking or curing as necessary.

[Non-porous substrate]
The non-porous substrate is used as a support matrix (support) of the heat-peelable pressure-sensitive adhesive sheet and has non-porosity. The non-porous substrate is not particularly limited as long as it is a non-porous substrate. Examples of non-porous substrates include metal non-porous substrates such as metal foils and metal plates; plastic non-porous substrates such as plastic films and sheets; rubber-based non-porous groups such as rubber sheets. Suitable non-porous materials such as materials and laminates thereof (particularly, a laminate of a plastic non-porous substrate and another non-porous substrate, a laminate of plastic films (or sheets), etc.) Thin leaves can be used. As the non-porous substrate, a plastic non-porous substrate such as a plastic film or sheet can be suitably used. As a raw material in such a plastic film or sheet, for example, α-olefin such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA) and the like is used as a monomer component. Olefin resins: Polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polyamide (nylon), wholly aromatic polyamide Amide resins such as (aramid); polyetheretherketone (PEEK) and the like. These materials can be used alone or in combination of two or more.

  When a plastic non-porous substrate is used as the non-porous substrate, the deformability such as elongation may be controlled by a stretching process or the like. Moreover, as a non-porous base material, when using a radiation curable substance for a thermally expansible adhesive layer etc., it is preferable to use what does not inhibit radiation transmission.

  The thickness of the non-porous substrate can be appropriately selected according to the strength, flexibility, purpose of use, and the like, for example, generally 1000 μm or less (for example, 1 to 1000 μm), preferably 1 to 500 μm, more preferably Is about 3 to 300 μm, particularly preferably about 5 to 250 μm, but is not limited thereto. The non-porous substrate may have a single layer form or a laminated form.

  The surface of the non-porous substrate has a conventional surface treatment, for example, corona treatment, chromic acid treatment, ozone exposure, flame exposure, high piezoelectric impact exposure, ionizing radiation treatment, etc., in order to improve the adhesion with the porous material layer etc. These may be subjected to an oxidation treatment or the like by a chemical or physical method, or may be subjected to a coating treatment with a primer.

[Heat-expandable adhesive layer]
The heat-expandable pressure-sensitive adhesive layer is a layer (a pressure-sensitive adhesive layer containing a foaming agent) containing at least a pressure-sensitive adhesive for imparting tackiness and a foaming agent for imparting thermal expansibility. , Have heat-expandable or foamable properties. Therefore, when sticking a work piece (adhered body) on the heat-expandable pressure-sensitive adhesive layer and fixing it, and applying desired processing to the work piece, the excellent adhesiveness of the heat-peelable pressure-sensitive adhesive sheet Because the workpiece is firmly fixed on the heat-expandable adhesive layer, the processing can be performed smoothly. After processing, the heat-expandable adhesive layer is heated to foam the foaming agent. And / or by thermally expanding, the thermally expandable adhesive layer expands, and this expansion reduces the adhesion area (contact area) between the thermally expandable adhesive layer and the processed workpiece (adhered body). , Adhesive strength by the heat-expandable pressure-sensitive adhesive layer is sufficiently reduced, and the processed product can be easily peeled from the heat-peelable pressure-sensitive adhesive sheet without any damage.

  Although it does not restrict | limit especially as a foaming agent, A thermally expansible microsphere can be used suitably. A foaming agent can be used individually or in combination of 2 or more types. The heat-expandable microsphere can be appropriately selected from known heat-expandable microspheres. As the thermally expandable microsphere, a foaming agent that is encapsulated in a microcapsule can be suitably used. Examples of such thermally expandable microspheres include microspheres in which substances such as isobutane, propane, and pentane that are easily gasified and expanded by heating are encapsulated in an elastic shell. 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 present invention, as the foaming agent, foaming agents other than the thermally expandable microspheres can also be used. As such a foaming agent, various foaming agents such as various inorganic foaming agents and organic foaming agents can be appropriately selected and used. Typical examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, various azides and the like. Representative examples of organic foaming agents include, for example, water; chlorofluorinated alkane compounds such as trichloromonofluoromethane and dichloromonofluoromethane; azobisisobutyronitrile, azodicarbonamide, and barium azodi. Azo compounds such as carboxylate; hydrazine compounds such as p-toluenesulfonyl hydrazide, diphenylsulfone-3,3'-disulfonyl hydrazide, 4,4'-oxybis (benzenesulfonyl hydrazide), allyl bis (sulfonyl hydrazide); p- Semicarbazide compounds such as toluylenesulfonyl semicarbazide and 4,4′-oxybis (benzenesulfonyl semicarbazide); Triazole compounds such as 5-morpholyl-1,2,3,4-thiatriazole; N, N′-dinitrosopene Methylene terrorism Ramin, N, N'-dimethyl -N, N'N-nitroso compounds such as dinitrosoterephthalamide, and the like.

  In order to reduce the adhesive force of the heat-expandable pressure-sensitive adhesive layer efficiently and stably by heat treatment, it has an appropriate strength that does not rupture until the volume expansion coefficient is 5 times or more, especially 7 times or more, particularly 10 times or more. A foaming agent is preferred.

  The blending amount of the foaming agent (such as thermally expandable microspheres) can be appropriately set according to the expansion ratio of the thermally expandable pressure-sensitive adhesive layer or the decrease in adhesive strength, but generally the pressure-sensitive adhesive that forms the heat-expandable pressure-sensitive adhesive layer. The amount is, for example, 1 to 150 parts by weight, preferably 25 to 120 parts by weight, based on 100 parts by weight of the base polymer.

  The pressure-sensitive adhesive used in the heat-expandable pressure-sensitive adhesive layer is not particularly limited, and can be appropriately selected from known pressure-sensitive adhesives. More specifically, as the adhesive, for example, acrylic adhesive, rubber adhesive, vinyl alkyl ether adhesive, silicone adhesive, polyester adhesive, polyamide adhesive, urethane adhesive, Examples thereof include fluorine-based pressure-sensitive adhesives, styrene-diene block copolymer-based pressure-sensitive adhesives, and creep property-improved pressure-sensitive adhesives obtained by blending these pressure-sensitive adhesives with a hot-melt resin having a melting point of about 200 ° C. or less. In addition, as the pressure-sensitive adhesive, a radiation curable pressure-sensitive adhesive (or energy beam curable pressure-sensitive adhesive) can be used. An adhesive can be used individually or in combination of 2 or more types. The pressure-sensitive adhesive is preferably one that does not restrain foaming and / or expansion of a foaming agent (such as thermally expandable microspheres) as much as possible when the thermally expandable pressure-sensitive adhesive layer is heated and expanded.

As the pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive can be suitably used, and an acrylic pressure-sensitive adhesive is particularly preferable. As an acrylic adhesive, an acrylic adhesive based on an acrylic polymer (homopolymer or copolymer) using one or more (meth) acrylic acid alkyl esters as monomer components. Agents. 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, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; maleic anhydride, itaconic anhydride Acid anhydride group-containing monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, ( Hydroxyl group-containing monomers such as hydroxydecyl (meth) acrylate, hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl methacrylate; styrene sulfonic acid, allyl sulfonic acid, 2- (meth) a Sulfonic acid group-containing monomers such as rilamido-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid; phosphoric acid such as 2-hydroxyethyl acryloyl phosphate Group-containing monomers: (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meta ) Acrylamide, N-methylolpropane (meth) acrylamide and other (N-substituted) amide monomers; (meth) acrylic acid aminoethyl, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) acrylic acid -(Meth) acrylic acid aminoalkyl monomers such as butylaminoethyl; (meth) acrylic acid alkoxyalkyl monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate; N-cyclohexylmaleimide, N- Maleimide monomers such as isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide; N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, Itaconic imide monomers such as N-cyclohexyl leuconconimide and N-lauryl itaconimide; N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide Succinimide monomers such as synimide and N- (meth) acryloyl-8-oxyoctamethylene succinimide; vinyl esters such as vinyl acetate and vinyl propionate; N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone and N-vinyl Pyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- ( Nitrogen-containing heterocyclic monomers such as (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine and N-vinylmorpholine; N-vinylcarboxylic acid amides; styrene monomers such as styrene and α-methylstyrene; N-vinylcaprolactam Any lactam monomer; Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; Polyethylene glycol (meth) acrylate, Polypropylene glycol (meth) acrylate, (Meth) Glycol acrylic ester monomers such as methoxyethylene glycol acrylate and methoxypolypropylene glycol (meth) acrylate; tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, heterocycles such as silicone (meth) acrylate, halogen atoms, Acrylic acid ester monomers having silicon atoms, 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, urethane acrylate, divinylbenzene, butyl di (meth) acrylate, hexyl di (meth) acrylate and other polyfunctional monomers; isoprene, butadiene, isobutylene and other olefinic monomers; methyl vinyl ether, ethyl vinyl ether and other vinyl ethers And monomers. These monomer components can be used alone or in combination of two or more.

  Rubber-based adhesives include natural rubber and various synthetic rubbers [for example, polyisoprene rubber, styrene / butadiene (SB) rubber, styrene / isoprene (SI) rubber, styrene / isoprene / styrene block copolymer (SIS). ) Rubber, Styrene / Butadiene / Styrene Block Copolymer (SBS) Rubber, Styrene / Ethylene / Butylene / Styrene Block Copolymer (SEBS) Rubber, Styrene / Ethylene / Propylene / Styrene Block Copolymer (SEPS) Rubber, Styrene -Ethylene / propylene block copolymer (SEP) rubber, recycled rubber, butyl rubber, polyisobutylene, and modified products thereof] as a base polymer.

  In addition to polymer components such as an adhesive component (base polymer), the pressure-sensitive adhesive is a cross-linking agent, tackifier, pigment, dye, filler, anti-aging agent, conductive material, An appropriate additive such as an antistatic agent or a plasticizer may be contained.

  As the crosslinking agent, for example, 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, Examples thereof include metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, amine-based crosslinking agents, and the like, and isocyanate-based crosslinking agents and epoxy-based crosslinking agents can be suitably used. Examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, and 1,6-hexamethylene diisocyanate; cyclopentylene diisocyanate, cyclohexylene diisocyanate, Cycloaliphatic polyisocyanates such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'- Aromatic polyisocyanates such as diphenylmethane diisocyanate and xylylene diisocyanate, and the like, and other trimethylolpropane / tolylene diisocyanate trimer adducts [Japan Polyurethane Industry Co., Ltd.] , Trade name "Coronate L"], trimethylolpropane / hexamethylene diisocyanate trimer adduct [Nippon Polyurethane Industry Co., Ltd. under the trade name "Coronate HL"], and the like are also used. Examples of the epoxy crosslinking agent include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, 1, 6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, penta Erythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycid In addition to ruether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether, Examples thereof include epoxy resins having two or more.

  Examples of the tackifier include rosin derivatives [for example, rosin, polymerized rosin, hydrogenated rosin and derivatives thereof (such as rosin ester resins and hydrogenated rosin ester resins)], terpene resins (for example, Terpene resin, aromatic modified terpene resin, hydrogenated terpene resin, terpene-phenol resin, etc.), phenolic resin (eg phenol-formaldehyde resin, alkylphenol-formaldehyde resin etc.), petroleum hydrocarbon resin [eg aliphatic type Petroleum resins, aromatic petroleum resins, alicyclic petroleum resins hydrogenated with aromatic petroleum resins (alicyclic saturated hydrocarbon resins), etc.], styrene resins, chroman resins (eg, coumarone indene) Resin, etc.).

  The heat-expandable pressure-sensitive adhesive layer is commonly used to form a sheet-like layer by mixing, for example, a pressure-sensitive adhesive, a foaming agent (such as heat-expandable microspheres), and a solvent or other additive as necessary. This method can be used. Specifically, for example, a pressure-sensitive adhesive, a foaming agent (such as thermally expandable microspheres), and a mixture containing a solvent and other additives as necessary are applied onto the porous material layer or the rubbery organic elastic layer. A method of applying the mixture on a suitable separator (such as a release paper) to form a thermally expandable adhesive layer, and transferring (transferring) the mixture onto a porous material layer or a rubbery organic elastic layer. Thus, a thermally 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 the adhesiveness reduction property, and is, for example, about 5 to 300 μm, preferably about 20 to 150 μm. However, when thermally expandable microspheres are used as the foaming agent, the thickness of the thermally expandable pressure-sensitive adhesive layer is preferably thicker than the maximum particle diameter of the contained thermally expandable microspheres. When the thickness of the heat-expandable pressure-sensitive adhesive layer is too thin, the surface smoothness is impaired by the unevenness of the heat-expandable microspheres, and the adhesiveness before heating (unfoamed state) is lowered. In addition, the degree of deformation of the heat-expandable pressure-sensitive adhesive layer by heat treatment is small, and the adhesive force is not easily lowered. On the other hand, if the thickness of the heat-expandable pressure-sensitive adhesive layer is too thick, cohesive failure tends to occur in the heat-expandable pressure-sensitive adhesive layer after foaming by heat treatment.

[Rubber organic elastic layer]
In FIG. 1B, a rubber-like organic elastic layer is provided from the viewpoint of imparting deformability of the heat-peelable pressure-sensitive adhesive sheet and improving peelability after heating, but the rubber-like organic elastic layer is necessary. It is a layer provided according to this, and is not necessarily provided. Thus, by providing the rubber-like organic elastic layer, when the heat-peelable pressure-sensitive adhesive sheet is adhered to the adherend (workpiece or the like) using the heat-expandable pressure-sensitive adhesive layer, the heat-peelable pressure-sensitive adhesive sheet is used. The surface of the thermally expandable pressure-sensitive adhesive layer in the sheet can be made to follow the surface shape of the adherend satisfactorily to increase the adhesion area, 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 can be controlled with high degree (accuracy), and the heat-expandable pressure-sensitive adhesive layer can be expanded preferentially and uniformly in the thickness direction. That is, the rubber-like organic elastic layer has a function of providing a large adhesion area by following the surface shape of the adherend when the heat peelable pressure sensitive adhesive sheet is adhered to the adherend, and the heat peelable pressure sensitive adhesive sheet. When the heat-expandable pressure-sensitive adhesive layer is heated to foam and / or expand in order to release the adherend, the heat-expandable pressure-sensitive adhesive sheet is restrained from foaming and / or expansion in the surface direction. It can serve to promote the formation of undele structure due to the three-dimensional structural change of the layer.

  The rubbery organic elastic layer can be provided between the non-porous substrate and the porous material layer, or between the porous material layer and the thermally expandable adhesive layer. The rubbery organic elastic layer may be provided with only one layer or may be provided with two or more layers. The rubbery organic elastic layer may have a single layer structure or a multilayer structure. 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.

  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. Moreover, an adhesive substance such as an adhesive constituting the thermally expandable adhesive layer can also be used as a constituent material of the rubbery organic elastic layer.

  The rubbery organic elastic layer is, for example, a method (coating method) in which a coating liquid containing a rubbery organic elastic layer forming material such as natural rubber, synthetic rubber, or synthetic resin having rubber elasticity is applied on a predetermined surface (coating method), A method of adhering a film made of a rubbery 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 adhesive layers (dry laminating method), A method of co-extruding a resin composition containing a constituent material of a non-porous substrate, a resin composition containing a constituent material of a porous material layer, and a resin composition containing the rubber-like organic elastic layer forming material (co-extruding) It can be formed by a forming method such as an extrusion method).

  The thickness of the rubbery organic elastic layer is, for example, about 5 to 300 μm, preferably about 20 to 150 μm. If the thickness of the rubbery organic elastic layer is too thin, a three-dimensional structural change after heating and foaming cannot be formed, and the peelability may deteriorate.

  As the rubber-like organic elastic layer, when a radiation curable substance is used for the heat-expandable adhesive layer or the like, it is preferable to use a layer that does not inhibit the transmission of radiation.

[Separator]
In FIGS. 1A to 1B, a separator (release liner) is used as a protective material for the surface (adhesive surface) of the thermally expandable adhesive layer, but the separator can be used as necessary. , Not necessarily used. When an adhesive layer other than the heat-expandable adhesive layer is provided, a separator (release liner) may be used as a protective material for the adhesive layer. The separator is peeled off when an adhesive layer (such as a thermally expandable adhesive layer) protected by the separator is used (that is, when an adherend is attached to the adhesive layer protected by the separator). .

  As a separator, both surfaces may be mold release surfaces, or only one surface (one surface) may be a mold release surface. As the separator, one or two separators having a release surface on one side or both sides may be used, or only one separator having a release surface on both sides may be used. Good.

  As such a separator, a known or commonly used release paper can be used. Specifically, as the separator, for example, a substrate having a release agent layer such as a plastic film or paper surface-treated with a release agent such as silicone, long chain alkyl, fluorine, or molybdenum sulfide; polytetrafluoro A low-adhesive substrate made of a fluoropolymer such as ethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, chlorofluoroethylene / vinylidene fluoride copolymer; A low-adhesive substrate made of a nonpolar polymer such as an olefin resin (for example, polyethylene, polypropylene, etc.) can be used.

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

[Other layers]
In the heat-peelable pressure-sensitive adhesive sheet of the present invention, it is sufficient that a porous material layer and a thermally expandable pressure-sensitive adhesive layer are formed in this order on at least one surface of the non-porous substrate. A heat-peelable pressure-sensitive adhesive sheet in which a porous material layer and a heat-expandable pressure-sensitive adhesive layer are formed in this order on one side, and a porous material layer and a heat-expandable pressure-sensitive adhesive layer on one surface of a non-porous substrate Are formed in this order, and a heat-expandable pressure-sensitive adhesive layer is formed on the other surface with or without a porous material layer. Heating in a form in which a porous material layer and a thermally expandable adhesive layer are formed in this order on the surface, and a non-thermally expandable adhesive layer (adhesive layer that does not have thermal expandability) is formed on the other surface Examples include a peelable pressure-sensitive adhesive sheet.

  Further, in the heat-peelable pressure-sensitive adhesive sheet of the present invention, between the non-porous substrate and the thermally expandable pressure-sensitive adhesive layer (that is, between the non-porous substrate and the porous material layer, or between the porous material layer and the heat-sensitive adhesive layer). One layer or two or more intermediate layers (rubber-like organic elastic layer, release agent layer, primer layer, etc.) may be provided between the expandable adhesive layer.

(Non-thermal expansion adhesive layer)
The pressure-sensitive adhesive for forming the non-thermally expandable pressure-sensitive adhesive layer is not particularly limited, and pressure-sensitive adhesives exemplified as the pressure-sensitive adhesive used in the above-mentioned heat-expandable pressure-sensitive adhesive layer (for example, rubber-based pressure-sensitive adhesive, acrylic pressure-sensitive adhesive) , Vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, styrene-diene block copolymer adhesives, adhesives with improved creep characteristics Well-known or commonly used pressure-sensitive adhesives such as an adhesive and a radiation curable pressure-sensitive adhesive). These pressure-sensitive adhesives can be used alone or in combination of two or more. In addition to polymer components such as an adhesive component (base polymer), a pressure-sensitive adhesive for forming a non-thermally expandable pressure-sensitive adhesive layer, a cross-linking agent, a tackifier, a pigment, Appropriate additives such as dyes, fillers, anti-aging agents, conductive materials, and antistatic agents may be blended.

  The thickness of the non-thermally expandable pressure-sensitive adhesive layer may be, for example, 300 μm or less (for example, 1 to 300 μm, preferably 5 to 100 μm). In addition, as a method for forming the non-thermally expandable adhesive layer, the same method as the thermally expandable adhesive layer (for example, a method of applying on a predetermined face material, after forming an adhesive layer by applying on a separator, For example, a method of transferring this onto a predetermined surface can be used. The non-thermally expandable pressure-sensitive adhesive layer may have a single layer structure or a multilayer structure.

  The heat-peelable pressure-sensitive adhesive sheet of the present invention has either a form of a double-sided pressure-sensitive adhesive sheet in which both surfaces are pressure-sensitive adhesive surfaces (adhesive surfaces) or a form of a pressure-sensitive adhesive sheet in which only one surface is a pressure-sensitive adhesive surface. Also good. In the present invention, as the heat-peelable pressure-sensitive adhesive sheet, a heat-peelable pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer (that is, a heat-expandable pressure-sensitive adhesive layer) is formed only on one side of the non-porous substrate is suitable.

  The heat-peelable pressure-sensitive adhesive sheet may be formed in a form wound in a roll shape, or may be formed in a form in which sheets are laminated. For example, when the heat-peelable pressure-sensitive adhesive sheet has a form in which only one surface is a pressure-sensitive adhesive surface and is wound in a roll shape, the heat-expandable pressure-sensitive adhesive layer is protected in a roll state with a separator. A non-porous substrate, a thermally expandable adhesive layer formed on one surface of the non-porous substrate via a porous material layer, and on the thermally expandable adhesive layer It can be produced as a heat-peelable pressure-sensitive adhesive sheet wound in a roll shape in a state constituted by the formed separator and wound in a roll shape. In addition, as the heat-peelable pressure-sensitive adhesive sheet in a state wound or wound, a non-porous substrate and heat formed on one surface of the non-porous substrate via a porous material layer You may be comprised by the expandable adhesion layer and the peeling process layer (back process layer) formed in the other surface of the said non-porous base material.

  Thus, the heat-peelable pressure-sensitive adhesive sheet can have a form such as a sheet form or a tape form.

  Since the heat-peelable pressure-sensitive adhesive sheet of the present invention has the above-described configuration, it can be suitably used as a heat-peelable pressure-sensitive adhesive sheet used for fixing the workpiece when the workpiece is processed. . The heat-peelable pressure-sensitive adhesive sheet can also be used as a protective material when conveying the adherend. Furthermore, the heat-peelable pressure-sensitive adhesive sheet can be suitably used as a recycle label.

  When using a heat-peelable pressure-sensitive adhesive sheet as a heat-peelable pressure-sensitive adhesive sheet for fixing (for temporary fixing) during processing of a workpiece, the workpiece to be processed (adhered body) to be processed on the thermally expandable pressure-sensitive adhesive layer The workpiece can be processed by pasting and processing the workpiece. In addition, it can select arbitrarily as a process at the time of processing to a workpiece, for example, the electrode printing process (pattern formation process etc.) to a green sheet, a lamination process, a pressurization process (pressurization press) Process), a cutting process (a polishing process, a dicing process, etc.), a baking process, etc. are mentioned, and an assembly process etc. are mentioned to others.

  Then, after processing the processed product (especially after achieving the adhesion purpose or when it is desired to release the adhesive state), the workpiece is heated to a temperature equal to or higher than the foaming start temperature of the foaming agent in the thermally expandable adhesive layer. Accordingly, the processed product (processed product) subjected to the processing process can be isolated by reducing the adhesive force and peeling or separating the processed product subjected to the processing process. In addition, as a heat treatment method at the time of peeling or separating a processed product that has been processed, for example, an appropriate heating means such as a hot plate, a hot air dryer, a near infrared lamp, an air dryer, or the like is used. be able to. The heating temperature may be equal to or higher than the thermal expansion start temperature (foaming start temperature) of the foaming agent (thermally expandable microspheres, etc.) in the thermally expandable adhesive layer, but the conditions for the heat treatment are the surface condition of the workpiece. It can be set appropriately depending on the reduction of the adhesion area due to the type of foaming agent (thermally expansible microspheres, etc.), the heat resistance of the non-porous substrate or workpiece, 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 1 to 90 seconds (hot plate or the like) or 5 to 15 minutes (hot air dryer or the like). 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.

  In addition, the articles | goods (a to-be-adhered body or a to-be-processed product) hold | maintained with the heat-peelable adhesive sheet of this invention can be selected arbitrarily. Specifically, the adherend includes electronic parts such as semiconductor wafers (silicon 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, a printed circuit board (such as a multilayer ceramic sheet), and a so-called “green sheet” can be mentioned. An adherend may be individual or may be combined 2 or more types.

  Thus, after making an adherend (workpiece) adhere to a heat-peelable adhesive sheet, various processed goods (processed adherend) can be obtained by performing a processing treatment. For example, when electronic parts such as a semiconductor wafer are used as the adherend, electronic parts and circuit boards can be obtained as processed products. 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.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, Example 2 is described as a reference example.

Example 1
On a polyester film (trade name “Melenex S-100 μ” manufactured by Teijin DuPont Films; thickness: 100 μm) as a non-porous substrate, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2- Ethylhexyl: 30 parts by weight, 2-hydroxyethyl acrylate: acrylic copolymer having 5 parts by weight of monomer component: 100 parts by weight of isocyanate-based crosslinking agent (trade name “Coronate L” Nippon Polyurethane Industry Co., Ltd. Manufactured): 1 part by weight and a resin composition (mixture) containing toluene as a solvent was applied so that the thickness after drying was 20 μm, and dried by heating at 120 ° C. for 3 minutes to give a rubbery organic elasticity. A non-woven fabric (trade name “CB-125 base paper” manufactured by Nippon Daishowa Paperboard West Japan Ltd .; thickness: about 50 μm, pores is formed on the rubbery organic elastic layer. : By bonding a 70%), via a rubber-like organic elastic layer on a non-porous substrate to form a non-woven fabric layer as a porous material layer.

  Further, on the separator, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2-ethylhexyl: 30 parts by weight, acrylic acid 2-hydroxyethyl: 5 parts by weight as an acrylic copolymer) ): Thickness after drying a resin composition (mixture) containing 1 part by weight of an isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.) and 100 parts by weight of toluene with respect to 100 parts by weight. Applied to a thickness of 20 μm, and dried by heating at 120 ° C. for 3 minutes to form a rubbery organic elastic layer. The rubbery organic elastic layer is a non-woven fabric layer formed on a non-porous substrate; In the form of contact, the rubbery organic elastic layer on the separator was bonded to the nonwoven fabric layer, and the separator was removed.

  Next, on the separator, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2-ethylhexyl: 30 parts by weight, acrylic acid 2-hydroxyethyl: 5 parts by weight acrylic copolymer having monomer components) ): 100 parts by weight of isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 1.5 parts by weight and rosin phenol-based tackifier (trade name “Sumilite Resin PR-12603N” “Sumitomo Bakelite Co., Ltd.”: 10 parts by weight, thermally expandable microspheres as a foaming agent (trade name “Matsumoto Microsphere F-501D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.): 30 parts by weight and toluene as a solvent The resin composition (mixture) to be applied is applied so that the thickness after drying is 40 μm, and is heat-dried at 70 ° C. for 3 minutes. In a form in which the thermally expandable adhesive layer is in contact with the rubbery organic elastic layer formed on the nonwoven fabric layer, the thermally expandable adhesive layer on the separator is bonded to the rubbery organic elastic layer, A heat-peelable pressure-sensitive adhesive sheet having a layer configuration of “non-porous substrate / rubber-like organic elastic layer / nonwoven fabric layer / rubber-like organic elastic layer / thermally expandable pressure-sensitive adhesive layer / separator” was produced.

(Example 2)
On a polyester film (trade name “Melenex S-100 μ” manufactured by Teijin DuPont Films; thickness: 100 μm) as a non-porous substrate, urethane polymer: 50 parts by weight, butyl acrylate: 35 parts by weight , Acrylic acid: 15 parts by weight, trade name “Irgacure 2959” (manufactured by Ciba Specialty Chemicals) as photopolymerization initiator: 0.15 parts by weight, and thermally expandable microspheres (trade name) “Matsumoto Microsphere F-50D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd .; foaming start temperature: 120 ° C .: a resin composition (mixture) containing 30 parts by weight and toluene as a solvent is applied and cured by irradiation with ultraviolet rays. Then, a heat treatment at 120 ° C. is applied to foam the foaming agent, and a foam layer as a porous material layer (thickness: about 150 μm, porosity: 80%) It was formed.

  Next, on the separator, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2-ethylhexyl: 30 parts by weight, acrylic acid 2-hydroxyethyl: 5 parts by weight acrylic copolymer having monomer components) ): 100 parts by weight of isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 1.5 parts by weight and rosin phenol-based tackifier (trade name “Sumilite Resin PR-12603N” “Sumitomo Bakelite Co., Ltd.”: 10 parts by weight, thermally expandable microspheres as a foaming agent (trade name “Matsumoto Microsphere F-501D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.): 30 parts by weight and toluene as a solvent The resin composition (mixture) to be applied is applied so that the thickness after drying is 40 μm, and is heat-dried at 70 ° C. for 3 minutes. And the thermally expandable adhesive layer on the separator is bonded to the foam layer in a form in which the thermally expandable adhesive layer is in contact with the foam layer formed on the non-porous substrate, A heat-peelable pressure-sensitive adhesive sheet having a layer configuration of “porous substrate / foam layer / thermally expandable pressure-sensitive adhesive layer / separator” was prepared.

(Comparative Example 1)
On a polyester film (trade name “Melenex S-100 μ” manufactured by Teijin DuPont Films; thickness: 100 μm) as a non-porous substrate, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2- Ethylhexyl: 30 parts by weight, 2-hydroxyethyl acrylate: acrylic copolymer having 5 parts by weight of monomer component: 100 parts by weight of isocyanate-based crosslinking agent (trade name “Coronate L” Nippon Polyurethane Industry Co., Ltd. Manufactured): 1 part by weight and a resin composition (mixture) containing toluene as a solvent was applied so that the thickness after drying was 20 μm, and dried by heating at 120 ° C. for 3 minutes to form a rubbery organic elastic layer. Formed.

  Next, on the separator, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2-ethylhexyl: 30 parts by weight, acrylic acid 2-hydroxyethyl: 5 parts by weight acrylic copolymer having monomer components) ): 100 parts by weight of isocyanate-based crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 1.5 parts by weight and rosin phenol-based tackifier (trade name “Sumilite Resin PR-12603N” “Sumitomo Bakelite Co., Ltd.”: 10 parts by weight, thermally expandable microspheres as a foaming agent (trade name “Matsumoto Microsphere F-501D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.): 30 parts by weight and toluene as a solvent The resin composition (mixture) to be applied is applied so that the thickness after drying is 40 μm, and is heat-dried at 70 ° C. for 3 minutes. The thermally expandable adhesive layer on the separator is bonded to the rubbery organic elastic layer in such a form that the thermally expandable adhesive layer is in contact with the rubbery organic elastic layer formed on the non-porous substrate. Thus, a heat-peelable pressure-sensitive adhesive sheet having a layer structure of “non-porous substrate / rubber-like organic elastic layer / thermally expandable pressure-sensitive adhesive layer / separator” was produced.

(Comparative Example 2)
On a polyester film (trade name “Melenex S-100 μ” manufactured by Teijin DuPont Films; thickness: 100 μm) as a non-porous substrate, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2- Ethylhexyl: 30 parts by weight, 2-hydroxyethyl acrylate: acrylic copolymer having 5 parts by weight of monomer component: 100 parts by weight of isocyanate-based crosslinking agent (trade name “Coronate L” Nippon Polyurethane Industry Co., Ltd. Manufactured): 1 part by weight and a resin composition (mixture) containing toluene as a solvent was applied so that the thickness after drying was 20 μm, and dried by heating at 120 ° C. for 3 minutes to form a rubbery organic elastic layer. Formed.

  Next, on the separator, an acrylic copolymer (ethyl acrylate: 70 parts by weight, acrylic acid 2-ethylhexyl: 30 parts by weight, acrylic acid 2-hydroxyethyl: 5 parts by weight acrylic copolymer having monomer components) ): 100 parts by weight of isocyanate crosslinking agent (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.): 0.8 part by weight and rosin phenol-based tackifier (trade name “Sumilite Resin PR-12603N” “Sumitomo Bakelite Co., Ltd.”: 10 parts by weight, thermally expandable microspheres as a foaming agent (trade name “Matsumoto Microsphere F-501D” manufactured by Matsumoto Yushi Seiyaku Co., Ltd.): 30 parts by weight and toluene as a solvent The resin composition (mixture) to be applied is applied so that the thickness after drying is 40 μm, and is heat-dried at 70 ° C. for 3 minutes. The thermally expandable adhesive layer on the separator is bonded to the rubbery organic elastic layer in such a form that the thermally expandable adhesive layer is in contact with the rubbery organic elastic layer formed on the non-porous substrate. Thus, a heat-peelable pressure-sensitive adhesive sheet having a layer structure of “non-porous substrate / rubber-like organic elastic layer / thermally expandable pressure-sensitive adhesive layer / separator” was produced.

(Evaluation)
About the heat peelable adhesive sheet obtained in Examples 1-2 and Comparative Examples 1-2, adhesive force and heat peelability were measured or evaluated by the following measuring method or evaluation method.

(Measurement method of adhesive strength)
The heat-peelable pressure-sensitive adhesive sheet is cut into a size having a width of 20 mm and a length of 140 mm to produce a measurement sample. Further, a stainless plate (BA304) subjected to ultrasonic cleaning is used as the adherend. After peeling the separator from the measurement sample, after attaching a stainless steel plate on the thermally expandable adhesive layer in accordance with JIS Z 0237 in an atmosphere of 23 ± 2 ° C. and 50 ± 5% RH (specifically, A tensile tester with a thermostatic bath set to 23 ° C. (trade name “Product Name”) under a temperature of 23 ± 2 ° C. and a humidity of 50 ± 5% RH, and a 2 kg roller reciprocated once and bonded together. Shimadzu Autograph AG-1 20 kN (manufactured by Shimadzu Corporation) and left for 30 minutes. After leaving, the maximum load when the heat-peelable pressure-sensitive adhesive sheet was peeled off under the conditions of the peel angle: 180 ° and the tensile speed: 300 mm / min (maximum value of the load excluding the peak top in the initial measurement) was measured. Using this maximum load as the adhesive strength, the adhesive strength (peeling angle: 180 °, tensile speed: 300 mm / min, temperature: 23 ° C. ± 2, humidity: 50 ± 5% RH; N / 20 mm) is determined. The adhesive strength is shown in the column of “Adhesive strength (N / 20 mm)” in Table 1.

(Evaluation method of heat peelability)
The heat-peelable pressure-sensitive adhesive sheet is cut into a size having a width of 10 mm and a length of 40 mm to produce a measurement sample. Further, a stainless plate (BA304) subjected to ultrasonic cleaning is used as the adherend. After separating the separator from the measurement sample, a stainless steel plate was bonded onto the thermally expandable adhesive layer using a hand roller in an atmosphere of 23 ± 2 ° C. and 50 ± 5% RH, and then dried in an atmosphere of 50 ° C. Store for 1 day in the machine. After storage, take it out from the dryer, cool it at room temperature, apply heat treatment at 130 ° C. for 10 minutes (heat treatment with a hot air dryer), and peel off the stainless steel plate stuck on the heat-peelable adhesive sheet By visually observing, the case where the stainless steel plate was peeled from the heat-peelable pressure-sensitive adhesive sheet was evaluated as “◯”, and the case where the stainless steel plate was not peeled was regarded as “x”, and the heat-peelable property of the heat-peelable pressure-sensitive adhesive sheet was evaluated. The evaluation results are shown in the column of “heat peelability” in Table 1.

  As is clear from Table 1, the heat-peelable pressure-sensitive adhesive sheets according to Examples 1 and 2 and the heat-peelable pressure-sensitive adhesive sheet according to Comparative Example 1 have the same thermally expandable pressure-sensitive adhesive layer. Since the heat-peelable pressure-sensitive adhesive sheet according to Examples 1 and 2 has a porous material layer between the non-porous substrate and the thermally expandable pressure-sensitive adhesive layer, the heat-peelable pressure-sensitive adhesive sheet according to Comparative Example 1 Also excellent in adhesive strength. In addition, the heat-peelable pressure-sensitive adhesive sheets according to Examples 1 and 2 are superior in heat peelability to the heat-peelable pressure-sensitive adhesive sheet according to Comparative Example 2, and can be easily peeled off from the adherend. Have.

  Accordingly, the heat-peelable pressure-sensitive adhesive sheets according to Examples 1 and 2 corresponding to the present invention can be easily peeled off from the adherend by heat treatment at any time, even if the adhesiveness to the adherend is enhanced. It was confirmed that both stronger adhesiveness and easy peelability were compatible.

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

Explanation of symbols

1a, 1b Heat-peelable adhesive sheet 2 Non-porous substrate 3 Porous material layer 4 Rubber-like organic elastic layer 5 Thermally expandable adhesive layer 6 Separator (release liner)

Claims (6)

A heat-peelable pressure-sensitive adhesive sheet in which a thermally expandable pressure-sensitive adhesive layer containing a foaming agent is formed on at least one surface of a non-porous substrate,
Between the non-porous substrate and the thermally expandable adhesive layer formed on at least one surface of the non-porous substrate has a porous material layer having a porosity of 10% or more,
A heat-peelable pressure-sensitive adhesive sheet comprising a rubbery organic elastic layer between a non-porous substrate and a porous material layer. Heat peelable adhesive sheet of claim 1, wherein the porous material layer is a nonwoven layer. The heat-peelable pressure-sensitive adhesive sheet according to claim 1 or 2 , wherein the non-porous substrate is a polyester film or a sheet. The heat-peelable pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the porous material layer has a thickness of 5 to 250 µm. Between the non-porous substrate and the porous material layer, and / or, between the porous material layer and the heat-expandable pressure-sensitive adhesive layer, any claim 1-4 having a rubbery organic elastic layer The heat-peelable pressure-sensitive adhesive sheet according to any item. The heat-peelable pressure-sensitive adhesive sheet according to any one of claims 1 to 5 , which is used for fixing electronic parts when processing electronic parts.

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