JP2003160767A - Thermochromic heat-peelable pressure-sensitive adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermochromic heat-exfoliative-type pressure-sensitive adhesive sheet simply and efficiently peelable from an object to be adhered, and capable of finding out an optimum using temperature condition, by a heat treatment for a short time at an optional chance. <P>SOLUTION: This thermochromic heat-exfoliative-type pressure-sensitive adhesive sheet is provided with a thermally expandable pressure-sensitive adhesive layer containing a thermally expandable microsphere and a thermochromic microsphere pigment on at least one side of the base material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermochromic heat-peelable type capable of efficiently and easily peeling from an adherend and finding an optimum use temperature condition by heat treatment for a short time at any time. Regarding adhesive sheet.

[0002]

2. Description of the Related Art Conventionally, a heat-peelable pressure-sensitive adhesive sheet is known in which a pressure-sensitive adhesive layer containing a foaming agent such as heat-expandable microspheres or a swelling agent is provided on a base material (JP-A-56-61468).
JP-A-56-61469, JP-A-60-2526
No. 81). This heat-peelable pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet that has both adhesiveness and releasability after use,
By foaming or expanding a foaming agent or the like by heating, the adhesive force is reduced, and the adhesive is easily peeled from the adherend. Therefore, it is used as a temporary fixing means or a label for recycling in the manufacturing process of electronic parts.
However, in the conventional heat-peelable pressure-sensitive adhesive sheet, it is very difficult to confirm whether or not the pressure-sensitive adhesive sheet has a uniform temperature, and therefore it is difficult to find the temperature condition during use. Accordingly, insufficient heating and excessive heating may cause a problem such as peeling of an adherend, and for example, in a ceramic capacitor manufacturing process, a decrease in the yield of ceramic capacitors is a problem.

[0003]

Therefore, an object of the present invention is to easily confirm that a uniform temperature is applied to the pressure-sensitive adhesive sheet when the heat-peelable pressure-sensitive adhesive sheet is used, and to find the optimum operating temperature condition at an early stage. Another object of the present invention is to provide a heat-peelable pressure-sensitive adhesive sheet that leads to an improvement in yield of, for example, ceramic capacitors.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above-mentioned object, and as a result, as a result, a thermal expansion containing a heat-expandable microsphere and a thermochromic microsphere pigment on at least one side of a base material. In the pressure-sensitive adhesive sheet provided with a heat-sensitive adhesive layer, the heat-expandability is expressed by the heat-expandable microspheres, and the color-changing and color-developing property is expressed by the thermochromic microsphere pigment, and when the optimum temperature is applied to the sheet, It is possible to easily confirm that the surface color changes from milky white and other colors to mottled milky red and that the entire pressure sensitive adhesive sheet is uniformly heated. The present invention has been completed by discovering that can be determined. That is, the present invention provides a thermochromic heat-peelable pressure-sensitive adhesive sheet in which an adhesive layer containing heat-expandable microspheres and thermochromic microsphere pigments is provided on at least one side of a substrate.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The thermochromic heat-peelable pressure-sensitive adhesive sheet of the present invention comprises one or more heat-expandable pressure-sensitive adhesive layers containing heat-expandable microspheres and color-changing microsphere pigments on one or both sides of a substrate. I have. Further, a rubber-like organic elastic layer is interposed between the base material and the heat-expandable pressure-sensitive adhesive layer, if necessary. Examples thereof are shown in FIGS. 1 and 2. Reference numeral 1 is a base material, 2 is a rubber-like organic elastic layer, 3 is a heat-expandable adhesive layer, and 4 is a separator.

The heat-expandable pressure-sensitive adhesive layer containing the heat-expandable microspheres and the thermochromic microsphere pigment can be provided on one side or both sides of the base material, and a rubber-like organic elastic layer may also be provided on the base material if necessary. Can be provided on one side or both sides. A heat-peelable pressure-sensitive adhesive sheet having a heat-expandable pressure-sensitive adhesive layer containing a heat-expandable microsphere and a thermochromic microsphere pigment on one side of the substrate and an ordinary adhesive layer on the other side can also be used. The base material is
It is used as a support base such as an adhesive layer, and a plastic film or sheet is generally used. For example, paper, cloth,
Appropriate thin sheets such as a non-woven fabric, a metal foil, a plastic laminate thereof, a laminate of plastics, or the like may be used. The thickness of the base material is 500 μm or less, especially 1 to 300
The thickness is generally, but not limited to, generally 5 to 250 μm. The substrate used in the present invention is a substrate having excellent adhesion to the adhesive layer by a chemical or physical treatment that oxidizes the surface by chromic acid treatment, ozone exposure, flame exposure, high piezoelectric bombardment exposure, ionizing radiation treatment, etc. You can also

The heat-expandable pressure-sensitive adhesive layer contains heat-expandable microspheres (microcapsules) so that the pressure-sensitive adhesive sheet adhered to the adherend can be easily peeled from the adherend by heat treatment. The pressure-sensitive adhesive layer is peeled off by heating the pressure-sensitive adhesive layer with the expansive microspheres at any time and foaming and / or expanding the heat-expandable microspheres to reduce the adhesive area between the pressure-sensitive adhesive layer and the adherend. be able to. With a non-microencapsulated foaming agent, good peelability cannot be stably achieved. Examples of the heat-expandable microspheres include those encapsulated in a shell-forming substance by an appropriate coacervation method or an interfacial polymerization method, such as isobutane, propane, or pentane, which easily gasifies and exhibits heat-expandability. The shell can be used, for example, vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethylmethacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, etc. It just needs to be made of material. Such heat-expandable microspheres include commercially available products such as Microsphere (trade name, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.). The heat-expandable microspheres that can be preferably used from the viewpoint of the decrease in the adhesive strength of the adhesive layer due to the heat treatment,
It does not burst by foaming until it has a volume expansion coefficient of 5 times or more, especially 7 times or more, and particularly 10 times or more. The blending amount of the heat-expandable microspheres can be appropriately determined according to the expansion ratio of the pressure-sensitive adhesive layer, the decrease in adhesive strength, etc., but generally 1 to 150 parts by weight per 100 parts by weight of the base polymer forming the pressure-sensitive adhesive layer. In particular, it is 10 to 130 parts by weight, especially 25 to 100 parts by weight.

The heat-expandable pressure-sensitive adhesive layer has a thermochromic property,
To check if the sheet is evenly heated,
It also contains a thermochromic microsphere pigment, and by heating the adhesive layer at any time with the thermochromic microsphere pigment, the thermochromic microsphere pigment discolors or develops color, and it is possible to easily confirm the sheet part that has been heated. You can The thermochromic microsphere pigment, for example, an electron-donating color-developing organic compound such as diphenylmethanephthalides, phenylindolylazaphthalides, fluoranes and the like and a developer of the organic compound, alkyl. Selected from the group consisting of alcohols, esters, and ketones, which are color-changing temperature adjusting agents for the color reaction of the above-mentioned two components, and monophenols or polyphenols having a substituent such as a group, an aryl group, or a halogen. A thermochromic material composed of a homogeneous compatible solution containing one or more compounds as an essential component is generally known as a microencapsulation method, for example, an interfacial polymerization method, a liquid curing coating method, a phase from an aqueous solution. Those encapsulated in the shell-forming substance by a separation method or the like can be used. The shell containing the thermochromic material may be made of a heat-melting substance such as vinylidene chloride-acrylonitrile copolymer or polyvinyl alcohol. From the viewpoint of color change and color development of the adhesive layer due to heat treatment, the blending amount of the thermochromic microsphere pigment can be appropriately determined according to the degree of color change and color development of the adhesive layer, but in general, a base polymer forming the adhesive layer. 10
0.1 to 150 parts by weight, especially 1 to 50 parts by weight, and particularly 1 to 10 parts by weight per 0 parts by weight. If the amount of thermochromic microsphere pigment in the heat-expandable pressure-sensitive adhesive layer is too small, the color-changing property of the heat-expandable pressure-sensitive adhesive layer will not be obtained sufficiently, and it will be difficult to determine the appropriate temperature conditions during use. There are cases. In addition, if the amount of the thermochromic microsphere pigment is too large, the properties such as the adhesive force that the heat-expandable pressure-sensitive adhesive layer should have are affected, and a sufficient adhesive force cannot be obtained. It may occur.

The pressure-sensitive adhesive layer can be formed of a pressure-sensitive adhesive that allows foaming and / or expansion of the heat-expandable microspheres when heated, and does not restrain foaming and / or expansion of the heat-expandable microspheres when heated. Those are preferably used. Therefore, for forming the adhesive layer, for example, rubber-based, acrylic-based, vinyl alkyl ether-based, silicone-based, polyester-based, polyamide-based, urethane-based, styrene-diene block copolymer-based, thermal melting with a melting point of about 200 ° C or less, etc. Of known adhesives such as those having an improved creep property by blending an organic resin (for example, JP-A-56-61468 and JP-A-61-1748).
57, JP-A-63-17981, JP-A-5
6-13040, etc.) or two or more types thereof can be used. The pressure-sensitive adhesive may be a mixture of appropriate additives such as a cross-linking agent, a tackifier, a plasticizer, a filling agent and an antiaging agent. Generally, rubber-based adhesives containing natural rubber or various synthetic rubbers as base polymers, methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group, heptyl group, 2-ethylhexyl group, isooctyl group, isodecyl group. Group, dodecyl group, lauryl group, tridecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, etc. An acrylic pressure-sensitive adhesive having an acrylic copolymer using one or more of acrylic acid alkyl esters as a base polymer is used.

The above acrylic copolymer is used for the purpose of modifying cohesive force, heat resistance, cross-linking property, etc., if necessary, for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, and icotanic acid. Carboxyl group-containing monomers such as and maleic acid, fumaric acid and crotonic acid, acid anhydride monomers such as maleic anhydride and icotanic anhydride, hydroxyethyl (meth) acrylate and hydroxyethyl (meth) acrylate and (meth) Hydroxypropyl acrylate, hydroxybutyl (meth) acrylate and hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate and hydroxydecyl (meth) acrylate, hydroxylauryl (meth) acrylate and (4-hydroxymethyl) Cyclohexy ) - such as a hydroxyl group-containing monomers methyl methacrylate, styrene sulfonic acid and allyl sulfonic acid, 2- (meth) acrylamido-2
Sulfonic acid group-containing monomers such as methyl propane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate and (meth) acryloyloxynaphthalene sulfonic acid, (meth) acrylamide and N, N-dimethyl (meth) acrylamide , N-butyl (meth) acrylamide and N-methylol (meth)
(N-substituted) amide monomers such as acrylamide, N-methylolpropane (meth) acrylamide, aminoethyl (meth) acrylate, aminoethyl (meth) acrylate and N, N-dimethylaminoethyl (meth) acrylate, (Meth) acrylic acid alkylamino monomers such as t-butylaminoethyl (meth) acrylate,
Alkoxyalkyl (meth) acrylate monomers such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, maleimide-based monomers such as N-cyclohexylmaleimide and N-isopropylmaleimide, N-laurylmaleimide and N-phenylmaleimide. Monomer, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N
-Itaconimide-based monomers such as cyclohexyl itaconimide and N-lauryl itaconimide, N- (meth) acryloyloxymethylene succinimide and N-
Succinimide-based monomers such as (meth) acryloyl-6-oxyhexamethylenesuccinimide and N- (meth) acryloyl-8-oxyoctamethylenesuccinimide, vinyl acetate and vinyl propionate, N-vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine and Butyl piperidone, vinyl pyrimidine, vinyl piperazine, vinyl pyrazine, vinyl pyrrole, vinyl imidazole, vinyl oxazole, vinyl morpholine and N-vinyl carboxylic acid amides, styrene and α-methyl styrene, vinyl monomers such as N-vinyl caprolactam, acrylonitrile and Cyanoacrylate monomer such as methacrylonitrile, epoxy group-containing acrylic monomer such as glycidyl (meth) acrylate, (meth)
Glycol-based acrylic ester monomers such as polyethylene glycol acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate and methoxypolypropylene glycol (meth) acrylate, tetrahydrofurfuryl (meth) acrylate and fluorine (meth) acrylate. ) Acrylate, acrylic ester monomers such as silicone (meth) acrylate and 2-methoxyethyl 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, Poly (erythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, and other polyfunctional monomers; isoprene, butadiene, isobutylene, vinyl ether, etc. It may be a copolymer of the above.

A pressure-sensitive adhesive which can be preferably used from the viewpoint of a balance between an appropriate adhesive force before heat treatment and a decrease in adhesive force after heat treatment has a dynamic elastic modulus of 0.5 to 0.5 at room temperature to 150 ° C. It is based on a polymer in the range of 100 Pa. The heat-expandable pressure-sensitive adhesive layer is formed, for example, by mixing the heat-expandable microspheres and the like with a solvent, if necessary, and then adding the mixture onto the substrate through the rubber-like organic elastic layer as necessary.
Appropriate methods such as a method of applying more than one layer and a method of transferring an adhesive layer formed on a separator to a substrate according to the method can be performed.

The particle diameter of the heat-expandable microspheres is larger than the adhesive layer center line average roughness of 0.4 μm, and since the projections are caused by the heat-expandable microspheres, the particle diameter is larger than the adhesive layer thickness. Of large heat-expandable microspheres of 0.1-3%, especially 0.2-2%
It is desirable to contain some. If the amount of heat-expandable microspheres having a particle size larger than the thickness of the adhesive layer is too large, the surface roughness of the adhesive layer becomes too large, and it may be difficult to secure an effective adhesion area with the adherend before heating. The particle diameter of the thermochromic microsphere pigment is smaller than the average roughness of the center line of the pressure-sensitive adhesive layer, 0.4 μm, and it is desirable that the protrusions do not rise on the pressure-sensitive adhesive layer surface. If the amount of the thermochromic microspheres having a larger particle size than the thickness of the adhesive layer is too large, the surface roughness of the adhesive layer becomes too large, which may make it difficult to secure an effective area with the adherend before heating. The particle size of the heat-expandable microspheres and the thermochromic microsphere pigment may be adjusted during the production process of the microspheres, or may be adjusted by a means such as classification after the production. The thickness of the heat-expandable adhesive layer is 30
It is preferably 0 μm or less, and more preferably 100 μm or less. If the thickness is too large, cohesive failure may occur during peeling after the heat treatment, and adhesive residue that contaminates the adherend may easily occur. On the other hand, if the thickness is too small, the degree of deformation of the adhesive layer due to the heat treatment is small and the adhesive strength is poorly lowered, and it may be necessary to make the particle diameter of the thermally expandable microspheres to be added excessively small. From this point, the thickness of the adhesive layer is 5 μm or more,
In particular, it is preferably 10 μm or more, and particularly preferably 15 μm or more.

The rubber-like organic elastic layer, which is optionally arranged between the base material and the heat-expandable pressure-sensitive adhesive layer, has a surface whose surface shape when the heat-peelable pressure-sensitive adhesive sheet is adhered to the substrate. It has a function to provide a large adhesive area by following excellently, and facilitates controlling the heat expansion of the adhesive layer during heat peeling, and is superior in preferential expansion in the thickness direction and thickness uniformity as much as possible. The expansion adhesive layer can be formed. The rubber-like organic elastic layer is made of a natural rubber or synthetic rubber of 50 or less, preferably 40 or less, or a synthetic resin having rubber elasticity based on the D-type Dur hardness of ASTM D-2240 because of its function. It is preferably formed. Thickness is 500
It is generally 3 μm or less, especially 3 to 300 μm, especially 5 to 150 μm. Examples of the synthetic rubber or synthetic resin include nitrile-based, diene-based and acrylic-based synthetic rubbers,
Examples thereof include thermoplastic elastomers such as polyolefins and polyesters, ethylene / vinyl acetate copolymers, polyurethanes, synthetic resins having rubber elasticity such as polybutadiene and soft polyvinyl chloride. It should be noted that even an essentially hard polymer such as polyvinyl chloride, which has rubber elasticity in combination with a compounding agent such as a plasticizer or a softener, may be used in the present invention. Further, an adhesive substance such as the adhesive exemplified above as the adhesive can be preferably used for forming the rubber-like organic elastic layer. The formation of the rubber-like organic elastic layer,
For example, an appropriate method such as a method of applying a solution of the above-mentioned forming material on a base material or a method of adhering a film or the like made of the above-mentioned forming material to the base material may be used. In the present invention, the rubber-like organic elastic layer may be formed of an adhesive substance containing a natural rubber, a synthetic rubber or a synthetic resin having rubber elasticity as a main component, or a foamed film containing such a component as a main component. It may be formed.

In the thermochromic heat-peelable pressure-sensitive adhesive sheet of the present invention, as described above, for example, a composite comprising one or more heat-expandable pressure-sensitive adhesive layers and optionally a rubber-like organic elastic layer is separately formed. It can also be formed by a method of adhering it to a base material. The obtained heat-peelable pressure-sensitive adhesive sheet can be adhered to an adherend with a preset adhesive force at the time of adhering, and can be easily peeled or separated by heat treatment when it is desired to release the adhered state. Therefore, the thermochromic heat-peelable pressure-sensitive adhesive sheet of the present invention can be used for the purpose of permanently adhering an adherend composed of an appropriate article or the like, but a preferable use is to adhere the adherend for a predetermined time. This is an application that is required or desired to release the adhered state after adhering to achieve the adhering purpose. In particular, it is most suitable for processing a substrate having a metal-based material part (plating part) that tends to be difficult to peel off with a conventional heat-peelable pressure-sensitive adhesive sheet and a component processing step that requires a larger attachment area. The heat treatment conditions for making the pressure-sensitive adhesive sheet easily peelable from the adherend include the surface state of the adherend, the reduction of the adhesive area depending on the type of the heat-expandable microspheres, the base material and the adherend. It is determined by conditions such as heat resistance and heating method. General conditions are 100-2
50 ℃, 1 to 90 seconds (hot plate, etc.) or 5 to 15 minutes (hot air dryer, etc.). Under such heating conditions, the heat-expandable microspheres of the heat-expandable pressure-sensitive adhesive layer are usually expanded or / and foamed to expand and deform the pressure-sensitive adhesive layer, and the adhesive strength is reduced or lost.
The heat treatment can be performed at an appropriate stage depending on the purpose of use. 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 superheat source.

[0015]

EFFECT OF THE INVENTION According to the thermochromic heat-peelable pressure-sensitive adhesive sheet of the present invention, it can be easily confirmed that the pressure-sensitive adhesive sheet has a uniform temperature when the heat-peelable pressure-sensitive adhesive sheet is used. It can be found early.

[0016]

EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. Example 1 2-Ethylhexyl Acrylate-Ethyl Acrylate-Methyl Methacrylate (Weight Ratio = 30/70/5) Copolymer-based Pressure-sensitive Adhesive 100 parts by weight of polyurethane-based cross-linking agent 2
Incorporating parts by weight, heat-expandable microspheres (Matsumoto Microsphere F-50D: manufactured by Matsumoto Yushi Co., Ltd .: average particle size 1
3.5 μm) 30 parts by weight and thermochromic microsphere pigment (3-
1.5 parts by weight of diethylamino-7-chlorofluorane,
A thermochromic material was prepared by blending 5.0 parts by weight of 4,4′-bis (p-toluenesulfonylaminocarbonylamino) diphenylbetane and 50 parts by weight of bis-P-methylbenzene oxalate. Microcapsule pigment containing thermochromic material in thermofusible material using interfacial polymerization method: average particle size
6.8 μm) 1 part by weight to prepare a toluene solution. This was applied onto a polyester film having a thickness of 100 μm so that the thickness after drying would be 45 μm, and dried to obtain a heat-peelable pressure-sensitive adhesive sheet. Next, the heat-peelable pressure-sensitive adhesive sheet thus obtained was placed in a steady state at 100 ° C. for 1 minute for 130 minutes.
The heat treatment was performed on a hot plate at a temperature of 1 ° C. for 1 minute and a temperature of 150 ° C. for 1 minute, and after cooling, the color of the surface of the adhesive sheet was visually confirmed.

Example 2 100 parts by weight of a 2-ethylhexyl acrylate-ethyl acrylate-methyl methacrylate copolymer type pressure-sensitive adhesive having the same weight ratio as in Example 1 was applied to a polyester film having a thickness of 100 μm and a polyurethane crosslinking agent. A toluene solution prepared by blending 1 part by weight was applied so as to have a thickness after drying of 10 μm and dried to form a rubber-like organic elastic layer.
In the same manner as in Example 1, 100 parts by weight of a 2-ethylhexyl acrylate-ethyl acrylate-methyl methacrylate copolymer-based pressure-sensitive adhesive was mixed with 2 parts by weight of a polyurethane-based cross-linking agent, and heat-expandable microspheres ( Matsumoto Microsphere F-50D: Matsumoto Yushi: Average particle size 13.
5 μm) 30 parts by weight and thermochromic microsphere pigment (3-diethylamino-7-chlorofluorane 1.5 parts by weight, 4,
A thermochromic material was prepared by blending 5.0 parts by weight of 4'-bis (p-toluenesulfonylaminocarbonylamino) diphenylbetane and 50 parts by weight of bis-P-methylbenzene oxalate. Microcapsule pigment in which a thermochromic material is encapsulated in a thermofusible material using an interfacial polymerization method: average particle size 6.8
μm) to prepare a toluene solution containing 1 part by weight,
This is applied onto a separator so that the thickness after drying is 35 μm, dried to form an adhesive layer, and then bonded to the rubber-like organic elastic body side of the polyester film on which the above-mentioned rubber-like organic elastic body is formed, and heated. A peelable pressure-sensitive adhesive sheet was obtained. Next, the resulting heat-peelable pressure-sensitive adhesive sheet
The heat treatment was performed on a hot plate at 100 ° C. × 1 minute, 130 ° C. × 1 minute, 150 ° C. × 1 minute, and after cooling, the color of the adhesive sheet was visually confirmed.

Comparative Example 1 A heat-peelable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the thermochromic microsphere pigment was not added to the pressure-sensitive adhesive layer.

Comparative Example 2 A heat-peelable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 2 except that the thermochromic microsphere pigment was not added to the pressure-sensitive adhesive layer.

Evaluation Test Table 1 shows the surface colors of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples under each heating condition.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a heat-peelable pressure-sensitive adhesive sheet of the present invention.

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

[Explanation of symbols] 1: Base material 2: Rubber-like organic elastic layer 3: Thermal expansion layer 4: Separator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yukio Arimitsu             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Kazuyuki Kiuchi             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 4J004 AA04 AA05 AA06 AA07 AA08                       AA09 AA10 AA14 AA15 AA16                       CA01 CA08 CB01 CB02 CB03                       CC02 FA05                 4J040 CA011 DC072 DD022 DD051                       DD072 DF011 DF041 DF051                       DF052 DF081 DF082 DF091                       DG001 ED001 EF001 EG001                       EJ032 EK031 MA10 MB03                       NA19

Claims (2)

[Claims] 1. A thermochromic heat-peelable pressure-sensitive adhesive sheet comprising a base material and a heat-expandable pressure-sensitive adhesive layer containing a heat-expandable microsphere and a thermochromic microsphere pigment provided on at least one side of the base material. 2. A thermochromic heat-peelable pressure-sensitive adhesive comprising a base material and a heat-expandable pressure-sensitive adhesive layer containing a heat-expandable microsphere and a thermochromic microsphere pigment provided on at least one side of a substrate through a rubber-like organic elastic layer. Sheet.