JP2009035660A - Method for peeling foamed self-adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for peeling a foamed self-adhesive sheet which comprises making a foamed self-adhesive sheet excellent in the adhesion property to be easily peelable from its adherend. <P>SOLUTION: In the method, the adherends 20, 30 and a laminate with the foamed adhesive sheet 10 having at least one side adhered to the bodies 20, 30 to be adhered are placed under a reduced pressure of 7.5×10<SP>4</SP>Pa or lower. Thereby, a volume of bubbles 40, 45 in the foamed adhesive sheet 10 is expanded to reduce the adhesion surface, and thus, adherends are easily peeled off. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for peeling a foamed pressure-sensitive adhesive sheet, and more particularly to a method for peeling a foamed pressure-sensitive adhesive sheet comprising a heat conductive pressure-sensitive adhesive composition.

  An electronic component such as a plasma display panel (PDP), an integrated circuit (IC) chip, or the like has increased in calorific value as its performance becomes higher. As a result, there is a need to take measures against functional failures due to temperature rise. In general, a method of diffusing heat by attaching a heat sink such as a heat sink, a heat radiating metal plate, or a heat radiating fin to a heat generating body such as an electronic component is employed. Various heat conductive sheets are used to efficiently conduct heat from the heating element to the heat radiating body. In general, a heat conductive pressure sensitive adhesive sheet is required for fixing the heat generating element and the heat radiating element. It is said. The heat conductive pressure sensitive adhesive sheet has excellent pressure sensitive adhesive properties even when the shape of the heat generating body and the heat radiating body is not flat such as a curved surface or an uneven surface, and has a buffering property. A foamed adhesive sheet having a specific thickness and flexibility is preferably used.

  As the foamed pressure-sensitive adhesive sheet, for example, Patent Document 1 discloses a thermally conductive pressure-sensitive adhesive composition containing a specific (meth) acrylic acid ester copolymer and a metal oxide and foamed. .

  Patent Document 2 discloses a composition comprising a (meth) acrylic acid ester polymer, a (meth) acrylic acid ester monomer mixture, a thermally conductive inorganic compound, a thermal polymerization initiator, and a foaming agent. Discloses a thermally conductive pressure-sensitive sheet-like foam obtained by sheeting, polymerization, and foaming.

These foam pressure-sensitive adhesive sheets are indispensable to have excellent pressure-sensitive adhesive properties in order to tightly fix the heating element and the heat radiating body. However, if the foam pressure-sensitive adhesive sheet fails to stick during production, the sheet is peeled off once. It is required that the sheet can be easily peeled off without damaging the sheet so that the foamed adhesive sheet can be peeled off from the member and reused when the product is discarded or the member is replaced.
JP 2005-239744 A JP 2006-213845 A

  However, the foamed pressure-sensitive adhesive sheet described in Patent Documents 1 and 2 is a sheet that has an excellent balance between hardness and pressure-sensitive adhesiveness, and also has excellent shape followability and pressure-sensitive adhesive retention, but is easily peelable. It was insufficient and it was not easy to re-paste or reuse.

  Therefore, the present invention provides a foamed adhesive sheet that can be easily peeled off by applying a simple treatment even if it is a foamed adhesive sheet with insufficient releasability. It is an object of the present invention to provide a sheet peeling method.

  As a result of conducting an experiment on a laminate having a foamed adhesive sheet between the adherend and the adherend, the inventor placed the laminate under specific conditions to change the volume of bubbles in the foamed adhesive sheet. Thus, it was found that the adherend and the pressure-sensitive adhesive sheet can be easily peeled off, and the peeling method of the present invention has been completed.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are added in parentheses, but the present invention is not limited to the illustrated embodiment.

The present invention is characterized in that the foamed pressure-sensitive adhesive sheet (10) having at least one side adhered to the adherend (20, 30) is placed under a reduced pressure of 7.5 × 10 ⁴ Pa or less. This is a peeling method. The bubbles (40, 45) in the foamed adhesive sheet expand when placed under reduced pressure.

In the present invention, the foamed pressure-sensitive adhesive sheet (10) having at least one side adhered to the adherend (20, 30) may be left for 1 minute or longer under a reduced pressure of 7.5 × 10 ⁴ Pa or less. Preferably, the time is 5 minutes or more and 90 minutes or less.

  In this invention, it is preferable that the foaming adhesive sheet (10) in which at least one side is adhere | attached on the to-be-adhered body (20, 30) is further heated at 40 to 150 degreeC.

  In the present invention, it is preferable that the foamed adhesive sheet (10) having at least one side adhered to the adherend (20, 30) is further subjected to a load in the direction in which the adhesive sheet is peeled off. By applying a load, the pressure-sensitive adhesive sheet can be more easily peeled off.

  In the present invention, the adherends (20, 30) are preferably glass and / or metal plates. The adherend made of such a material has high adhesiveness with the foamed pressure-sensitive adhesive sheet (10).

  In the present invention, the foamed pressure-sensitive adhesive sheet (10) preferably contains 10% by mass or more of an acrylate (co) polymer having a glass transition temperature of −20 ° C. or lower.

  In the present invention, the acrylate (co) polymer is preferably a polymer obtained by (co) polymerizing a (meth) acrylate having a C 2-18 alkyl group as a main component.

  In the present invention, the acrylic ester (co) polymer is obtained by (co) polymerizing a (meth) acrylic ester having an alkyl group having 2 to 18 carbon atoms and an organic acid group-containing monomer. A polymer is preferred.

  In this invention, it is preferable that a foaming adhesive sheet (10) contains 50 to 90 mass% of inorganic fillers, and it is preferable that an inorganic filler is aluminum hydroxide.

The present invention provides a method for peeling a foamed pressure-sensitive adhesive sheet 10 characterized by placing the foamed pressure-sensitive adhesive sheet 10 having at least one side adhered to the adherends 20 and 30 under a reduced pressure of 7.5 × 10 ⁴ Pa or less. It is. The bubbles 40 in the foamed pressure-sensitive adhesive sheet expand when placed under reduced pressure, and change the shape of the foamed pressure-sensitive adhesive sheet. Specifically, protrusions as shown in FIG. 2A are formed at a plurality of locations on the surface of the pressure-sensitive adhesive sheet 10 due to the expansion of the internal bubbles 40, and the adherends 20 and 30 and the pressure-sensitive adhesive sheet 10 As shown in FIG. 2B, it is considered that the adhesion surface between the adherends 20 and 30 and the adhesive sheet 10 decreases due to the expansion of the bubbles 45 existing at the interface. By forming the convex portions in this way, a force acts in the direction in which the adhesive sheet 10 is peeled from the inside, and the adhesive surface with the adherends 20 and 30 is reduced, so that easy peeling is achieved. It becomes possible.

  In the present invention, by leaving for 1 minute or longer under the above conditions, the reduction of the adhesive surface due to the expansion of the bubbles 40 and 45 at the interface between the adherends 20 and 30 and the foamed adhesive sheet 40 proceeds. Peeling can be performed more easily. The treatment time is 1 minute or longer, and particularly preferably 5 minutes to 90 minutes. The peelability of the pressure-sensitive adhesive sheet is improved by being placed under the above conditions for a long time. However, even if it is too long, the working efficiency is poor, which is not preferable.

  In the present invention, by further heating to 40 ° C. to 150 ° C., the foamed pressure-sensitive adhesive sheet 10 becomes more flexible, and the expansion resistance of the bubbles 40 and 45 becomes smaller. Due to the expansion, the bubbles 40 and 45 inside the sheet 10 are further expanded, so that the adhesion surface is further reduced and peeling can be performed more easily.

  In the present invention, the pressure-sensitive adhesive sheet can be more easily peeled by applying a load in the direction in which the pressure-sensitive adhesive sheet peels. The weight of the load is not particularly limited, but too much load is not preferable because it leads to a decrease in workability.

  In the present invention, by using the adherends 20 and 30 as glass and / or metal plates, the adhesiveness with the foamed adhesive tape 10 can be further improved, and it is suitable for a plasma display panel, an IC chip and the like. It can be set as the heat generating body and heat radiator which are used.

  In the present invention, the foamed adhesive sheet 10 contains 10% by mass or more of an acrylate (co) polymer having a glass transition temperature of −20 ° C. or less. Preferably, the acrylate (co) polymer is carbon A polymer obtained by (co) polymerizing a (meth) acrylic acid ester having an alkyl group of 2 to 18 as a main component, or the above acrylate (co) polymer is an alkyl having 2 to 18 carbon atoms. (Meth) acrylic acid ester having a group and an organic acid group-containing monomer are (co) polymerized, and the foamed adhesive sheet 10 is inorganic filler, preferably aluminum hydroxide inorganic By including 50 mass% or more and 90 mass% or less of a filler, it can be set as the foaming adhesive sheet 10 which has the outstanding easy peelability, and combines with the peeling method of this invention. In a short time, it can be separated easily and efficiently foam the adhesive sheet 10.

  As described above, according to the method for peeling a foamed adhesive sheet of the present invention, even if the sheet is damaged in the manufacturing stage, labor for peeling the sheet can be reduced, and a product can be manufactured efficiently. Further, the foamed adhesive sheet can be peeled off when the product is discarded or the member is replaced, and the member or foamed adhesive sheet can be reused.

  Embodiments of the present invention will be described below with reference to the drawings.

  The schematic diagram of the laminated body of the to-be-adhered bodies 20 and 30 and the foaming adhesive sheet 10 which are the peeling object of this invention in FIG. 1 is shown. The foamed pressure-sensitive adhesive sheet 10 has flexibility, includes bubbles 40 and 45 (see FIG. 2), and is adhered to one side of the adherend 20 or the adherend 30. In the present embodiment, the adherends 20 and 30 have a flat plate shape, but may have other shapes as long as they can be bonded by the foamed adhesive sheet 10. The bubbles 40 and 45 in the foamed adhesive sheet 10 may be uniformly dispersed or may be biased. The volume of the bubbles 40 and 45 is not particularly limited. Further, the content of the bubbles 40 and 45 in the entire foamed adhesive sheet 10 is not particularly limited, but it is sufficient that the content of the bubbles in the foamed adhesive sheet 10 that is usually used is included. Although the bubble 40 and 45 should just be contained about 10%-40% of the volume of this, the effect of this invention will appear notably, so that the content rate of the bubble 40 and 45 becomes large.

<The peeling method of the foaming adhesive sheet 10 of this invention>
(Peeling method 1)
The foamed pressure-sensitive adhesive sheet 10 having at least one side adhered to the adherends 20 and 30 is 7.5 × 10 ⁴ Pa or less, preferably 6.0 × 10 ⁴ Pa or less, and more preferably 3.0 × 10 ⁴ Pa. It changes to the state which can be peeled easily by being under the following pressure reduction. The decompression method is not particularly limited as long as it is a general decompression method, but the inside of the container in which the laminated body is accommodated may be almost vacuumed using a pump, a vacuum dryer, or the like. At this time, as described later, the container preferably has a temperature adjusting function. Since the foamed adhesive sheet 10 has flexibility, the volume of the bubbles 40 and 45 expands when placed under a reduced pressure of 7.5 × 10 ⁴ Pa or less (Boil's law). As a result, the shape of the foamed pressure-sensitive adhesive sheet 10 changes as shown in FIGS. 2A and 2B, and a force acts in the direction in which the foamed pressure-sensitive adhesive sheet 10 and the adherends 20 and 30 are peeled off. It is considered that an uneven shape is generated on the surface of the foamed pressure-sensitive adhesive sheet 10 and the adhesion surface is reduced. Therefore, the foamed pressure-sensitive adhesive sheet 10 after the present peeling method 1 can be easily peeled off from the adherend 20 or the adherend 30. The foamed pressure-sensitive adhesive sheet 10 may be peeled off naturally from the adherend 20 or the adherend 30 due to reduced pressure, and even if not, the foamed adhesive sheet 10 may be peeled off for a while after returning to atmospheric pressure. Easy.

(Peeling method 2)
The foamed pressure-sensitive adhesive sheet 10 having at least one side adhered to the adherends 20 and 30 changes to a more easily peelable state by being left for a certain period of time under a reduced pressure of 7.5 × 10 ⁴ Pa or less. To do. The longer the time, the more the adhesive surface decreases and the more easily peelable it becomes, but it is preferable to set it to 1 minute or more in consideration of work efficiency etc. Among them, 5 minutes or more and 90 minutes or less More preferably.

(Peeling method 3)
In addition to the peeling method 1 or 2, the foamed pressure-sensitive adhesive sheet 10 is changed to a state where it can be easily peeled by being placed in an atmosphere at a certain temperature or higher. About temperature range, the adherends 20 and 30 and the foaming adhesive sheet 10 should just be the temperature which can hold | maintain a fixed form, and it is preferable that it is 40 to 150 degreeC. By heating within such a temperature range, since the external pressure is constant, the bubbles 40 and 45 further expand (Charles' law). Further, depending on the material of the foamed adhesive sheet 10, there are some which increase flexibility by heating, reduce the expansion resistance of the bubbles 40 and 45, and promote expansion. When the bubbles 40 and 45 are further expanded, the adhesive surface between the foamed adhesive tape 10 and the adherends 20 and 30 is further reduced and can be more easily peeled off.

(Peeling method 4)
In addition to any of the peeling methods 1 to 3, a load is applied in the direction in which the foamed pressure-sensitive adhesive sheet peels, so that the state can be more easily peeled. The magnitude of the load is not particularly limited. However, if the load is excessively applied, there is a possibility that inconveniences such as deterioration of workability may occur. Therefore, it is necessary to adjust appropriately according to workability and environment.

<Adherents 20 and 30 and foamed adhesive sheet 10>
The peeling method of the present invention is remarkably effective for the adherends 20 and 30 and the foamed adhesive sheet 10 described below, and can shorten the re-sticking process and the reuse process. In addition, the foamed adhesive sheet 10 described below is a heat conduction for efficiently conducting heat conduction from a heating element such as an electronic component such as a plasma display panel (PDP) or an integrated circuit (IC) chip to a heat radiating body. It is suitably used as a sheet.

(Adherents 20, 30)
The adherends 20 and 30 are not particularly limited as long as they are materials that can be bonded by the foamed pressure-sensitive adhesive sheet 10, but are preferably glass and / or metal plates. Glass and metal plates are suitably used as heat generators and heat radiators of electronic components such as plasma display panels and IC chips, and are good examples to which the peeling method of the present invention can be applied.

(Composition of foamed adhesive sheet 10)
As the foamed pressure-sensitive adhesive sheet 10, a conventionally known one can be used, but it is preferable to contain 10% by mass or more of a (meth) acrylic acid ester (co) polymer having a glass transition temperature of −20 ° C. or less, and 20% by mass. As mentioned above, it is more preferable to contain 40 mass% or less. Further, the acrylate (co) polymer is more preferably a polymer obtained by (co) polymerizing (meth) acrylate having a C 2-18 alkyl group as a main component. Among them, a polymer obtained by (co) polymerizing a (meth) acrylic acid ester having an alkyl group having 2 to 18 carbon atoms and an organic acid group-containing monomer is particularly preferable. In addition, (meth) acrylic acid ester means acrylic acid ester and / or methacrylic acid ester.

  The (meth) acrylic acid ester (co) polymer has a glass transition temperature of −20 ° C. or lower, preferably a (meth) acrylic acid ester having an alkyl group having 2 to 18 carbon atoms as a main component. As long as it is a polymer formed by (co) polymerization, for example, ethyl acrylate (the glass transition temperature of the homopolymer is −24 ° C.), propyl acrylate (-37 ° C.), Butyl acrylate (-54 ° C), sec-butyl acrylate (-22 ° C), heptyl acrylate (-60 ° C), hexyl acrylate (-61 ° C), octyl acrylate (-65 ° C) ), 2-ethylhexyl acrylate (-50 ° C), 2-methoxyethyl acrylate (-50 ° C), 3-methoxypropyl acrylate (-75 ° C), 3-methoxybutyl acrylate (Meth) acrylic acid ester, such as 2-ethoxymethyl acrylate (-50 ° C), octyl methacrylate (-25 ° C), decyl methacrylate (-49 ° C) The thing which polymerized the body is mentioned. These (meth) acrylic acid ester monomers may be used alone or in combination of two or more.

  The organic acid group-containing monomer is not particularly limited, but representative examples mainly include monomers having an organic acid group such as a carboxyl group, an acid anhydride group, and a sulfonic acid group. In addition to these, monomers containing sulfenic acid groups, sulfinic acid groups, phosphoric acid groups, and the like can also be used. Specific examples of the monomer having a carboxyl group include α, β-ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; α, β- such as itaconic acid, maleic acid, and fumaric acid. And ethylenically unsaturated polyvalent carboxylic acids; α, β-ethylenically unsaturated polyvalent carboxylic acid partial esters such as methyl itaconate, butyl maleate and propyl fumarate; Moreover, what has group which can be induced | guided | derived to a carboxyl group by hydrolysis etc., such as maleic anhydride and itaconic anhydride, can be used similarly. Specific examples of the monomer having a sulfonic acid group include allyl sulfonic acid, methallyl sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, α, β-unsaturated sulfonic acid such as acrylamide-2-methylpropane sulfonic acid, and the like. These salts can be mentioned. Among these monomers having an organic acid group, monomers having a carboxyl group are more preferable, and among these, acrylic acid and methacrylic acid are particularly preferable. These are industrially inexpensive and can be easily obtained, have good copolymerizability with other monomer components, and are preferable in terms of productivity. These monomers having an organic acid group may be used alone or in combination of two or more.

  The monomer unit having these organic acid groups has a monomer unit derived from 20 to 0.1% by mass, preferably 15 to 0.5% by mass in the (meth) acrylic acid ester copolymer. It is desirable to be used for polymerization in such amounts. In use within the above range, the viscosity of the polymerization system at the time of polymerization can be maintained in an appropriate range. The monomer unit having an organic acid group can be easily and preferably introduced into a (meth) acrylic acid ester polymer by polymerization of a monomer having an organic acid group. After forming the ester polymer, an organic acid group may be introduced by a known polymer reaction.

  It is preferable that the foamed pressure-sensitive adhesive sheet 10 further includes a thermally conductive inorganic filler. As a result, the foamed adhesive sheet 10 having excellent thermal conductivity can be obtained, and heat can be efficiently released from the heating element of the electronic component such as a plasma display panel or IC chip to the radiator. Moreover, the flame-retardant property which was excellent in the foaming adhesive sheet 10 can also be provided.

  Specific examples of inorganic fillers include beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, iron hydroxide, zinc hydroxide, aluminum hydroxide, gallium hydroxide, and indium hydroxide. Metal hydroxides such as alumina, magnesium oxide, beryllium oxide, titanium oxide, etc .; metal nitrides such as boron nitride, silicon nitride, aluminum nitride; carbides such as silicon carbide; copper, silver, iron, aluminum Metals such as nickel, carbon compounds such as diamond and carbon, silica powders such as quartz and quartz glass, etc., but metals of Group 2 (magnesium, calcium, strontium, barium, etc.) or Group 13 of the periodic table Preferred are hydroxides, oxides or nitrides of (aluminum, gallium, indium, etc.) Among them, aluminum hydroxide is particularly preferred. These inorganic fillers may be used alone or in combination of two or more.

  It is preferable that 50 mass% or more and 90 mass% or less are contained in a foaming adhesive sheet, and, as for an inorganic filler, it is more preferable that 60 mass% or more and 80 mass% or less are contained. When the content is within the above preferable range, the thermal conductivity, adhesive strength and hardness (shape followability resulting from) of the foamed pressure-sensitive adhesive sheet can be kept good.

  The foamed adhesive sheet 10 having the inorganic filler described above is heat for efficiently conducting heat from a heating element such as an electronic component such as a plasma display panel (PDP) or an integrated circuit (IC) chip to the radiator. It is suitably used as a conductive sheet.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to the examples. The “parts” and “%” used here are based on mass unless otherwise specified.

(Production of foamed adhesive sheet)
A reactor was charged with 100 parts of a monomer mixture composed of 90% 2-ethylhexyl acrylate and 10% acrylic acid, 0.03 parts 2,2′-azobisisobutyronitrile and 700 parts ethyl acetate. Then, after substitution with nitrogen, a polymerization reaction was carried out at 80 ° C. for 6 hours. The polymerization conversion rate was 97%. The obtained polymer was dried under reduced pressure to evaporate ethyl acetate to obtain a viscous solid copolymer (1). Mw of the copolymer (1) was 280000, and Mw / Mn was 3.1.

  In a mortar for a grinder, 100 parts of copolymer (1), 30 parts of 2-ethylhexyl acrylate, 2 parts of methacrylic acid and polyethylene glycol dimethacrylate (oxyethylene chain repeat number = approximately 23, manufactured by Shin-Nakamura Chemical Co., Ltd.) (Trade name “NK ester 23G (polyethylene glycol # 1000 dimethacrylate)”) (hereinafter abbreviated as “PEGDMA”) 32.8 parts of monomer mixture (1), thermal polymerization initiator 1.0 part of 1,6-bis (t-butylperoxycarbonyloxy) hexane (thermal decomposition temperature is 160 ° C.), p, p′-oxybis (benzenesulfonylhydrazide) which is a thermally decomposable blowing agent ) (Hereinafter abbreviated as “OBSH”) 0.2 parts and 200 parts of aluminum hydroxide (particle size 8 μm) are charged all at once. Mix well at room temperature with a machine. At this time, the amount of aluminum hydroxide with respect to 100 parts in total of the copolymer (1) and the monomer mixture (1) is 150 parts.

  Thereafter, the mixture was defoamed with stirring under reduced pressure to obtain a viscous liquid sample. A polyester film with a release agent was laid on the bottom of a mold having a length of 400 mm, a width of 400 mm, and a depth of 0.95 mm, and then the sample was poured into the mold and covered with a polyester film with a release agent. . This was removed from the mold. Hold the sample horizontally, and blow hot water at 155 ° C. vertically for 10 minutes from both the top and bottom to allow polymerization and foaming, and to form a foam sheet (1) covered on both sides with a polyester film with a release agent. Obtained.

  The completed sheet (1) was adhered onto an adherend (aluminum plate, glass plate) as follows to prepare a laminate sample.

(Sample preparation)
Remove the polyester film on one side of the foam sheet (1) cut to 100 mm length and 50 mm width, place it on an aluminum plate with a length of 150 mm, width 50 mm, and thickness 2 mm. The roller was rolled back and forth to pressure-bond the foam sheet (1) and the aluminum plate. The polyester film on the other side of the foam sheet (1) is peeled off, placed in the order of 150 mm long, 50 mm wide, 2 mm thick glass plate, 1 kg weight, and after 30 seconds, the weight is lowered, and the aluminum plate and the foam sheet (1) A sample (2) in which the glass plate was pasted was allowed to stand for 2 days or more to be completely adhered.

  The sample (2) was fixed to the shelf with the glass plate facing down, and placed in a vacuum constant temperature dryer (manufactured by Yamato Kagaku Co., Ltd., model DP43), and the atmospheric pressure and temperature were changed. For the load, a weight was suspended on the glass plate side. [For Examples 5 to 8 and Comparative Examples 1 to 7, a vacuum dryer (manufactured by ESPEC Corporation, model VAC-300PR) was used. ] After 30 minutes from the start of the test, ◎ indicates that the glass plate was completely peeled off, ○ indicates that the glass plate was peeled off, ○ indicates that the glass plate was slightly peeled, Δ indicates that there was no change. X was determined. Table 1 shows the results of evaluation by changing the atmospheric pressure, temperature, weight, and time.

  About Examples 1-8, after performing an experiment by changing each condition of temperature, weight, and time under reduced pressure, peeling evaluation was performed, and for Comparative Examples 1-7 under atmospheric pressure, An experiment was conducted by changing each condition of temperature, weight, and time, and then peeling was evaluated. From Table 1, the samples peeled off under reduced pressure were all peeled off from the entire glass plate, whereas the samples peeled off under atmospheric pressure had temperature, weight, and time. It can be seen that no change was observed at any condition. That is, the sample is placed under a reduced pressure to improve easy peelability. This is presumably because, as described above, the bubbles in the foamed pressure-sensitive adhesive sheet expand and deform the sheet by reducing the pressure-sensitive adhesive surface as a result. Moreover, when it sees about conditions other than atmospheric pressure about Examples 1-8, it turns out that the one where temperature is higher is favorable. As described above, this is considered to be because the bubbles in the foamed pressure-sensitive adhesive sheet are further expanded by being placed at a high temperature to further reduce the adhesive surface.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, the invention can be changed as appropriate without departing from the gist or concept of the invention that can be read from the claims and the entire specification, and the method for peeling the foamed adhesive sheet with such changes is also included in the technical scope of the present invention. Must be understood as being.

It is a schematic diagram which shows the laminated state of a to-be-adhered body and a foaming adhesive sheet. It is a conceptual diagram which shows how the bubble in a foaming adhesive sheet changes by giving the peeling method of this invention.

Explanation of symbols

10 Foamed adhesive sheet 20, 30 Substrate (especially glass or aluminum)
40, 45 bubbles

Claims (10)

A method for peeling a foamed pressure-sensitive adhesive sheet, comprising placing a foamed pressure-sensitive adhesive sheet having at least one side adhered to an adherend under a reduced pressure of 7.5 × 10 ⁴ Pa or less.   2. The method for peeling a foamed adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive sheet is kept under the reduced pressure for 1 minute or longer.   Furthermore, it heats to 40 to 150 degreeC, The peeling method of the foaming adhesive sheet of Claim 1 or 2 characterized by the above-mentioned.   Furthermore, a load is applied to the direction in which the said adhesive sheet peels, The peeling method of the foaming adhesive sheet of any one of Claims 1-3 characterized by the above-mentioned.   The method for peeling a foamed adhesive sheet according to claim 1, wherein the adherend is glass and / or a metal plate.   The said foaming adhesive sheet contains 10 mass% or more of acrylic acid ester (co) polymers whose glass transition temperature will be -20 degrees C or less, The any one of Claims 1-5 characterized by the above-mentioned. A method for peeling a foamed adhesive sheet.   The acrylic ester (co) polymer is a polymer obtained by (co) polymerizing a (meth) acrylic ester having a C 2-18 alkyl group as a main component. 6. A method for peeling a foamed pressure-sensitive adhesive sheet according to 6.   The acrylic ester (co) polymer is a polymer obtained by (co) polymerizing a (meth) acrylic ester having an alkyl group having 2 to 18 carbon atoms and an organic acid group-containing monomer. The peeling method of the foaming adhesive sheet of Claim 6 or 7 characterized by the above-mentioned.   The method for peeling a foamed pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the foamed pressure-sensitive adhesive sheet contains 50% by mass or more and 90% by mass or less of an inorganic filler. The method for peeling a foamed adhesive sheet according to claim 9, wherein the inorganic filler is aluminum hydroxide.

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