JP2008094957A - Pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and method for peeling work - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive excellent in initial tack and holding power and capable of being easily peeled from an adherend and from the desired side of an adherend without being partially left on the adherend, to provide a pressure-sensitive adhesive sheet coated therewith, and to provide a method for peeling a work stuck with the pressure-sensitive adhesive. <P>SOLUTION: The pressure-sensitive adhesive 40 for releasably bonding a work on an adherend comprises a pressure-sensitive adhesive layer 12 having a pressure-sensitive adhesive material 14, thermally meltable microcapsules 18 dispersed in the pressure-sensitive adhesive material 14, and a release agent 16 which is encapsulated in the microcapsules and lowers the adhesiveness of the pressure-sensitive adhesive material 14 and a pressure-sensitive adhesive layer 20 formed on the pressure-sensitive adhesive layer 12 and having a pressure-sensitive material 22 and thermally expansible particles 24 dispersed in the pressure-sensitive adhesive material 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and a workpiece peeling method, and in particular, a pressure-sensitive adhesive that easily peels from an adherend by heat treatment, a pressure-sensitive adhesive sheet using the pressure-sensitive adhesive, and the pressure-sensitive adhesive. The present invention relates to a method for peeling an attached workpiece.

  A pressure-sensitive adhesive or a pressure-sensitive adhesive sheet provided on a substrate which is a support is used for a wide range of applications such as label sticking. Applications of adhesives and pressure-sensitive adhesive sheets include temporary fixing of electronic parts on a production line and sticking of a recycle label. In such a field, it is required that an electronic component, a label, or the like can be easily peeled after being attached to an adherend using an adhesive or an adhesive sheet. From such a point of view, pressure-sensitive adhesives and pressure-sensitive adhesive sheets have been proposed in which the adhesive strength is reduced or lost by a predetermined treatment.

  For example, Patent Document 1 discloses a heat-peelable pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer containing thermally expandable resin particles is provided on a base material. This expands the heat-expandable resin particles in the pressure-sensitive adhesive layer, thereby reducing the adhesive force so that it can be easily peeled off from the adherend.

For example, Patent Document 2 discloses a pressure-sensitive adhesive containing microcapsules containing a release agent. This breaks the microcapsules by pressurization at the time of peeling, and reduces the adhesive strength of the pressure-sensitive adhesive by the release agent that has exuded from the microcapsules.
JP 60-252681 A JP 09-095650 A

  However, the pressure-sensitive adhesive sheet described in Patent Document 1 does not weaken the pressure-sensitive adhesive force, but peels the adherend and pressure-sensitive adhesive body with the expansion force of the thermally expandable resin particles. In some cases, no adhesive peelability was obtained, and an adhesive residue remained on the adherend.

  On the other hand, since the pressure-sensitive adhesive sheet described in Patent Document 2 weakens the pressure-sensitive adhesive strength by the action of a release agent, the pressure-sensitive adhesive strength of the pressure-sensitive adhesive can be greatly reduced. The possibility of remaining residues is low. However, in order to obtain such effects, it is necessary to apply pressure over the entire pressure-sensitive adhesive sheet, and in the case of a large pressure-sensitive adhesive sheet or a pressure-sensitive adhesive sheet affixed in a narrow housing that cannot be pressurized, it is easily peeled off. It was difficult to make.

  Moreover, although the adhesive is used to bond the two members, if only one of the two members is to be reused at the time of disposal, the adhesive residue may remain on the non-reused member. Although there is no, it is required not to leave a residue of the adhesive on the member to be reused. As described above, anisotropic peeling properties such as peeling without leaving a residue on only one side of the desired adhesive have been desired at the time of peeling, but there is no pressure-sensitive adhesive that can solve this. .

  An object of the present invention is to provide an adhesive that is excellent in initial adhesive strength and holding power, can be easily peeled off from an adherend at the time of peeling, and can be peeled off without leaving a residue on the adherend from one desired surface. Another object of the present invention is to provide a pressure-sensitive adhesive sheet and a method for peeling a workpiece attached using the pressure-sensitive adhesive.

  According to one aspect of the present invention, a first adhesive material, a microcapsule dispersed in the first adhesive material and melted by heat, and encapsulated in the microcapsule, the adhesive force of the adhesive material is increased. A first pressure-sensitive adhesive layer having a release agent for lowering, and formed on the first pressure-sensitive adhesive layer, dispersed in the second pressure-sensitive adhesive material and the second pressure-sensitive adhesive material, and expanded by heat. A pressure-sensitive adhesive having a second pressure-sensitive adhesive layer having first thermally expandable particles is provided.

  According to another aspect of the present invention, there is provided a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive is formed on a base material, wherein the pressure-sensitive adhesive is dispersed in the first pressure-sensitive adhesive material and the first pressure-sensitive adhesive material. Formed on the first pressure-sensitive adhesive layer, a first pressure-sensitive adhesive layer having a microcapsule that melts by heat, a release agent that is encapsulated in the microcapsule and reduces the pressure-sensitive adhesive force of the pressure-sensitive adhesive material, and There is provided a pressure-sensitive adhesive sheet having a second pressure-sensitive adhesive material and a second pressure-sensitive adhesive layer having first heat-expandable particles dispersed in the second pressure-sensitive adhesive material and expanded by heat.

  According to still another aspect of the present invention, a first pressure-sensitive adhesive material, a microcapsule dispersed in the first pressure-sensitive adhesive material and melted by heat on the adherend, and the microcapsule A first pressure-sensitive adhesive layer that is included and has a mold release agent that reduces the pressure-sensitive adhesive force of the pressure-sensitive adhesive material; a second pressure-sensitive adhesive material that is formed on the first pressure-sensitive adhesive layer; and the second pressure-sensitive adhesive layer. A method of peeling a workpiece affixed using a pressure-sensitive adhesive having a second pressure-sensitive adhesive layer having a thermally expandable particle that is dispersed in a material and expands by heat. A work peeling method is provided in which the microcapsules are melted and the thermally expandable particles are expanded, and the release agent is diffused into the first adhesive material to reduce the adhesive force.

  According to the present invention, the first has a microcapsule dispersed in the first adhesive material and melted by heat, and a release agent encapsulated in the microcapsule and reducing the adhesive strength of the first adhesive material. A pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer, dispersed in the second pressure-sensitive adhesive material, and thermally expandable particles that expand by heat, and Since the pressure-sensitive adhesive sheet using this is constituted, the pressure-sensitive adhesive can be easily peeled off only by performing a heat treatment and leaving almost no residue on a desired one-side adherend.

  Moreover, the adhesive force of an adhesive can be improved by providing the 3rd adhesive layer which does not contain a microcapsule or a thermally expansible particle on a 2nd adhesive layer.

  Moreover, the diffusibility of the mold release agent released from the microcapsules can be improved by dispersing thermally expandable particles that are expanded by heat in the first adhesive material. Thereby, it is possible to improve the peelability and further suppress the generation of residues.

  Further, by encapsulating thermally expandable particles that expand due to heat in the microcapsules in the first pressure-sensitive adhesive layer, the destruction of the microcapsules is promoted, and the diffusibility of the release agent released from the microcapsules is increased. Can be improved. Thereby, it is possible to improve the peelability and further suppress the generation of residues.

[First Embodiment]
The pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3.

  FIG. 1 is a schematic cross-sectional view showing the structure of the pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the present embodiment, and FIGS. 2 and 3 are views for explaining a workpiece peeling method according to the present embodiment.

  First, the pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the present embodiment will be described with reference to FIG.

  An adhesive layer 12 is formed on the separator (or base material) 10. The pressure-sensitive adhesive layer 12 is obtained by dispersing hot-melt microcapsules 18 enclosing a release agent 16 in a pressure-sensitive adhesive material 14. An adhesive layer 20 is formed on the adhesive layer 12. The pressure-sensitive adhesive layer 20 is obtained by dispersing thermally expandable particles 24 that expand in volume by heating in a pressure-sensitive adhesive material 22. A separator 26 is formed on the pressure-sensitive adhesive layer 20. Thus, an adhesive sheet is configured in which the adhesive 40 formed by laminating the two adhesive layers 12 and 20 is sandwiched between the separators 10 and 26.

Adhesive materials 12 and 20 are, for example, rubber-based, acrylic-based, vinyl alkyl ether-based, silicone-based, polyester-based, polyamide-based, urethane-based, styrene / diene block copolymer systems having a melting point of 200 ° C. or less. One type or two or more types of known adhesive materials can be used in combination, such as those having improved creep characteristics by blending. Moreover, you may mix | blend additives, such as a crosslinking agent, tackifier, a plasticizer, a filler, an antioxidant, suitably. In general, rubber adhesives based on natural rubber and various synthetic rubbers as a base polymer, methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group, heptyl group, cyclohexyl group, 2-ethylhexyl group, Acrylic acid or methacrylic acid having an alkyl group having 20 or less carbon atoms such as isooctyl group, isodecyl group, dodecyl group, uraryl group, tridecyl group, pentanedecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group An acrylic pressure-sensitive adhesive having a base polymer of an acrylic polymer using one or two or more of acrylic acid alkyl esters composed of an ester such as an acid can be used. Further, from the viewpoint of achieving a great decrease in the adhesive strength after heating, it is preferable to use a polymer having a dynamic elastic modulus from room temperature to 150 ° C. from 50,000 to 10,000,000 dyn / cm ² as the base polymer.

  The pressure-sensitive adhesive material 22 constituting the pressure-sensitive adhesive layer 20 is a material that allows foaming and / or expansion of the thermally expandable particles 24 during heating, and allows expansion and / or expansion of the thermally expandable particles during heating. It is desirable not to restrain as much as possible. In addition, as the adhesive materials 14 and 22, it is more preferable to use a material having a gap due to a pressing force due to expansion of a thermally expandable particle 24 described later.

  The microcapsule 18 includes a release agent 16 having a function of reducing the adhesive force of the pressure-sensitive adhesive layer 12 when coming into contact with the pressure-sensitive adhesive layer 12 and is made of a heat-meltable material.

  As the shell material of the microcapsule 18, for example, a heat-melting substance such as vinylidene chloride / acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, or the like can be applied. In particular, when a synthetic resin such as a melamine / formaldehyde resin or an isocyanate resin is used as the microcapsule 18, it is excellent in water resistance and solvent resistance, and is more preferable.

  The melting point of the microcapsule 18 is desirably 60 to 150 ° C. This is because if the melting point is less than 60 ° C., some microcapsules 18 may spontaneously melt, for example, even at room temperature, without heat treatment. In addition, if the melting point is higher than 150 ° C., heating at 200 ° C. or higher is necessary to heat-melt the microcapsules 18, and a general adherend may be thermally deteriorated. Here, the “melting point” means a melting peak temperature measured using a thermal differential scanning calorimeter (DSC) at a rate of temperature increase of 10 ± 1 ° C./min according to JIS K7121.

  The average particle size of the microcapsules 18 is desirably 1 to 50 μm. This is because if the average particle size is less than 1 μm, the content of the release agent contained in one microcapsule 18 decreases, and the adhesive force of the pressure-sensitive adhesive layer 12 cannot be sufficiently reduced. On the other hand, if the average particle size is larger than 50 μm, the microcapsules 18 having no adhesive force occupy most of the pressure-sensitive adhesive layer 12, and the pressure-sensitive adhesive layer 12 cannot obtain a sufficient adhesive force.

  The release agent 16 contained in the microcapsule 18 has a function of reducing the adhesive force of the pressure-sensitive adhesive layer 12 by being in contact with the pressure-sensitive adhesive material 14. As such a release agent 16, higher fatty acids, higher fatty acid derivatives, organopolysiloxane compounds, waxes, higher alcohols, mineral oils, animal oils, vegetable oils, silicone oils, and the like can be applied. Moreover, it is not limited to these materials, You may use together 2 or more types of mold release agents. Moreover, you may make it contain adjuvants, such as antioxidant and a ultraviolet absorber, as needed.

  It is desirable that the release agent 16 has a low viscosity. This is because if the release agent 16 is too viscous, it cannot diffuse sufficiently when released into the adhesive material 14, thereby reducing the contact area with the adhesive material 14. This is because the adhesive force cannot be sufficiently reduced.

  The release agent 16 is desirably contained in the range of 1 to 20 wt% with respect to the adhesive material 14. When the content ratio of the release agent 16 is less than 1 wt% with respect to the pressure-sensitive adhesive material 14, a sufficient release effect cannot be obtained, and the release agent 16 has a weight ratio with respect to the pressure-sensitive adhesive material 14. This is because if the amount is more than 20 wt%, sufficient adhesion cannot be obtained, and the adherend may be contaminated during peeling.

  The microcapsule 18 encapsulating the release agent 16 can be produced using a known method such as a coacervation method, an interfacial polymerization method, an in-situ polymerization method. In this case, it is preferable to use a synthetic resin such as a melamine / formaldehyde resin or an isocyanate resin as a wall film agent from the viewpoint of water resistance and solvent resistance.

  The thickness of the pressure-sensitive adhesive layer 12 containing the microcapsule 18 is such that the release agent 16 released from the microcapsule 18 easily reaches the interface between the pressure-sensitive adhesive layer 12 and the adherend 30. It is desirable to set in the range of 1.3 to 1.8 times the average particle size. Desirably, the thickness of the pressure-sensitive adhesive layer 12 is 1.3 times or more the average particle diameter of the microcapsules 18, and less than 1.3 times the average particle diameter of the microcapsules 18. This is because the amount of the microcapsules 18 that come into contact increases, and the adhesive force to the adherend 30 decreases. In addition, it is desirable that the thickness of the pressure-sensitive adhesive layer 12 is 1.8 times or less of the average particle diameter of the microcapsules 18, and when the thickness exceeds 2.0 times the average particle diameter of the microcapsules 18, the pressure-sensitive adhesive layer The distance between the interface between the adhesive layer 12 and the adherend 30 and the microcapsule 18 increases, and the release agent 16 released from the microcapsule 18 does not sufficiently reach the interface between the adhesive layer 12 and the adherend 30. Because there are things.

  The thermally expandable particles 24 are microspheres whose volume expands by heating, and function as an auxiliary agent for enhancing the peeling effect. As the thermally expandable particles 24, for example, an appropriate material that is easily gasified and exhibits thermal expandability, such as isobutane, propane, or pentane, is encapsulated in a shell forming material by a coacervation method, an interfacial polymerization method, or the like. Can be applied. As the shell, for example, a heat-melting substance such as vinylidene chloride / acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, or an appropriate substance that is destroyed by thermal expansion is applied. be able to. The thermally expandable particles 24 include commercially available products such as microspheres (trade name) manufactured by Matsumoto Yushi Co., Ltd.

  The expansion temperature of the thermally expandable particles 24 is desirably in the range of 80 to 200 ° C. This is because if the foaming temperature is less than 80 ° C., the heat-expandable particles 24 may be ruptured and the adhesiveness may be deteriorated even if the heat treatment is not performed, for example, at room temperature. Further, if the foaming temperature is higher than 200 ° C., heating at 200 ° C. or higher is required for foaming, and a general adherend may be thermally deteriorated. Here, the “foaming temperature” means a temperature at which the thermally expandable particles start to expand.

  Further, it is desirable that the expansion temperature of the thermally expandable particles 24 is higher than the melting point of the microcapsule 18 (for example, 10 ° C. or more). By setting the foaming temperature of the thermally expandable particles 24 to be higher than the melting point of the microcapsules 18, the release agent 16 oozes out from the microcapsules 18, and then the adhesive layers 12, Since the cracks are generated in 20, the release agent 16 can be effectively diffused in the pressure-sensitive adhesive layers 12 and 20.

  The thermally expandable particles 24 are desirably contained in the range of 1 to 20 wt% with respect to the adhesive material 22. When the content ratio of the heat-expandable particles 24 is less than 1 wt% with respect to the pressure-sensitive adhesive material 22, a sufficient effect cannot be obtained, and the heat-expandable particles 24 are in a weight ratio with respect to the pressure-sensitive adhesive material 22. It is because sufficient adhesiveness cannot be obtained when it is more than 20 wt%.

  The average particle diameter of the thermally expandable particles 24 is desirably 1 to 50 μm. This is because if the average particle size is less than 1 μm, a sufficient effect cannot be obtained because the expansion effect of the pressure-sensitive adhesive layers 12 and 20 is small even if the thermal expansion occurs. On the other hand, if the average particle size is larger than 50 μm, the heat-expandable particles 24 having no adhesive force occupy most of the pressure-sensitive adhesive layer 20, and the pressure-sensitive adhesive layer 20 cannot obtain a sufficient adhesive force. is there.

  From the viewpoint of reducing the adhesive strength of the pressure-sensitive adhesive layers 12 and 20 by heat treatment, the thermally expandable particles 24 that can be preferably used are those that do not burst by foaming until the volume expansion coefficient becomes 5 times or more, particularly 10 times or more. It is.

  The adhesive strength of the pressure-sensitive adhesive layers 12 and 20 composed of the above materials is such that the 180 ° peel adhesive strength (peel rate 300 mm / min) to the stainless steel plate at 25 ° C. is preferably 800 g / 25 mm or more, and 1000 g / More preferably, it is 25 mm or more. This is because if the adhesive strength at room temperature is less than 800 g / 25 mm, the adherend cannot be sufficiently retained and is not practical. Further, the adhesive strength after heating to the temperature at which peeling is caused, that is, the peeling design temperature, is preferably 80 g / 25 mm or less, and more preferably 30 g / 25 mm or less. This is because if the adhesive strength after the heat treatment exceeds 80 g / 25 mm, it is difficult to peel the adherend well.

  The separators 10 and 26 are release papers that are detachably attached to the adhesive layers 12 and 20, and are removed when the adhesive sheet is attached to an adherend. As the separators 10 and 26, general release paper materials used for the adhesive materials 14 and 22 can be applied. Separator 10,26 can be mainly comprised by a thin leaf body, such as a plastic film, paper, cloth, a nonwoven fabric, a metal stay, or those laminated bodies. The thickness of the separators 10 and 26 is generally 500 μm or less, particularly 5 to 250 μm, but is not limited thereto. Both separators 10 and 26 are not necessarily required, and only one of them may be used.

  The pressure-sensitive adhesive sheet shown in FIG. 1 forms a pressure-sensitive adhesive layer 12 on the separator 10 by applying a pressure-sensitive adhesive material 14 mixed with microcapsules 18 using a solvent as necessary. If necessary, a pressure-sensitive adhesive layer 20 is formed by applying a pressure-sensitive adhesive material 22 mixed with the thermally expandable particles 24 using a solvent, and a separator 26 is stuck on the pressure-sensitive adhesive layer 20. Can do. Conversely, they may be formed sequentially from the separator 26 side.

  Next, the workpiece peeling method according to the present embodiment will be described with reference to FIGS.

  Here, as shown in FIG. 2A, a case where a workpiece 50 that is a sticker such as a label is stuck on the adherend 30 by the adhesive 40 will be described as an example. The workpiece 50 may be attached to the adherend 30 by using the above-mentioned pressure-sensitive adhesive sheet, or the workpiece 50 may be stuck after the adhesive layer 12 and the adhesive layer 20 are formed on the adherend 30 in sequence. Also good. At the time of sticking, the pressure-sensitive adhesive layer 12 is positioned on the side of the object (the adherend 30) where it is not desired to leave a residue after peeling.

  In the state shown in FIG. 2A, since the release agent 16 is encapsulated in the microcapsule 18 and the thermally expanded particles 24 are not expanded, the adhesive 40 can sufficiently exert its adhesive force. . Thereby, the workpiece 50 is adhered to the adherend 30 with sufficient adhesive force by the adhesive layer 12 and the adhesive layer 20. The adhesive force at this time is 800 g / 25 mm or more, for example.

  Next, the pressure-sensitive adhesive 40 is heated using the heating means 60. The heat treatment condition is basically determined by the melting point of the shell material of the microcapsule 18 and the foaming temperature of the thermally expandable particles 24, the content of the microcapsule 18 and the thermally expandable particles, the surface state of the adherend 30, It is desirable to change according to conditions such as the reduction of the adhesion area due to the types of the microcapsules 18 and the thermally expandable particles 24, the heat resistance of the adherend 30 and the workpiece 50, and the like. Normal heat treatment conditions are 60 to 250 ° C., 1 to 90 seconds (hot plate or the like) or 5 to 15 minutes (hot air dryer or the like). The heating means 60 is not particularly limited as long as it can heat the adhesive 40, and a hot plate, an oven, a hot air dryer, or the like can be appropriately applied.

  When the temperature of the pressure-sensitive adhesive exceeds the melting point of the microcapsule 18, the microcapsule 18 melts (FIG. 2 (b)). Thereby, the release agent 16 enclosed in the microcapsule 18 is released into the pressure-sensitive adhesive layer 12 (FIG. 2C).

  When the temperature of the pressure-sensitive adhesive exceeds the foaming temperature of the heat-expandable particles 24, the heat-expandable particles 24 expand, and cracks are generated in the pressure-sensitive adhesive layers 12 and 20 due to the pressing force due to the expansion of the heat-expandable particles 24. The expansion of the thermally expandable particles 24 also has an effect of helping the destruction of the microcapsules 18 by the pressing force thereby. As a result, the release agent 16 released into the pressure-sensitive adhesive layer 12 diffuses along the crack, reaches the interface between the pressure-sensitive adhesive layer 12 and the adherend 30, and the pressure-sensitive adhesive layer 12 and the adherend 30 are separated from each other. The adhesive strength between them is reduced (FIG. 3A). The adhesive force of the adhesive 40 after the heat treatment is, for example, 80 g / 25 mm or less.

  Further, it is desirable that the expansion temperature of the thermally expandable particles 24 is higher than the melting point of the microcapsule 18 (for example, 10 ° C. or more). By doing so, the thermally expandable particles 24 can be expanded after the release agent 16 has sufficiently oozed from the microcapsule 18 into the pressure-sensitive adhesive layer 12. Thereby, the mold release agent 16 which oozes out in the adhesive layer 12 can be diffused effectively.

  When the workpiece 50 is peeled off in this state, peeling is performed between the adherend 30 having the lowest adhesive strength and the adhesive 40, and the workpiece 50 is peeled off with almost no residue remaining on the adherend 30. (FIG. 3B).

  As described above, according to the present embodiment, the first microcapsule dispersed in the adhesive material and melted by heat, and the release agent encapsulated in the microcapsule and reducing the adhesive strength of the adhesive material. A pressure-sensitive adhesive having a pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer, dispersed in the pressure-sensitive adhesive material, and thermally expandable particles, and the same Since the pressure-sensitive adhesive sheet is constituted, the pressure-sensitive adhesive can be easily peeled off by simply performing a heat treatment and leaving almost no residue on the desired one-side attachment surface.

[Second Embodiment]
The pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure similar to the adhesive and adhesive sheet by 1st Embodiment shown in FIG. 1 thru | or FIG. 3, and description is abbreviate | omitted or simplified.

  FIG. 4 is a schematic cross-sectional view showing the structure of the pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the present embodiment.

  An adhesive layer 12 is formed on the separator 10. The pressure-sensitive adhesive layer 12 is obtained by dispersing hot-melt microcapsules 18 enclosing a release agent 16 in a pressure-sensitive adhesive material 14. An adhesive layer 20 is formed on the adhesive layer 12. The pressure-sensitive adhesive layer 20 is obtained by dispersing thermally expandable particles 24 in a pressure-sensitive adhesive material 22. An adhesive layer 42 made of an adhesive material 44 is formed on the adhesive layer 20. A separator 26 is formed on the adhesive layer 42. Thus, an adhesive sheet is configured in which the adhesive 40 in which the three adhesive layers 12, 20, 42 are laminated is sandwiched between the separators 10, 26.

  The main feature of the pressure-sensitive adhesive sheet according to the present embodiment is that, in the pressure-sensitive adhesive sheet according to the first embodiment, the pressure-sensitive adhesive 40 does not contain a microcapsule enclosing a release agent or thermally expandable particles on the pressure-sensitive adhesive layer 20. The adhesive layer 42 made of the material 44 is further provided.

  In the pressure-sensitive adhesive sheet according to the first embodiment shown in FIG. 1, the materials that exhibit the adhesive force in the pressure-sensitive adhesive 40 are the pressure-sensitive adhesive materials 14 and 22. When the microcapsules 18 and the thermally expandable particles 24 that do not have adhesive strength themselves are added to the adhesive materials 14 and 22, the adhesive strength is reduced as compared with the case where they are not added. For example, in the example of the pressure-sensitive adhesive 40 according to the first embodiment shown in FIG. 2A, since the heat-expandable particles 24 are added to the pressure-sensitive adhesive layer 20, the heat-expandable particles 24 are not added. As a result, the adhesive force between the pressure-sensitive adhesive layer 20 and the workpiece 30 is reduced.

  Therefore, in the pressure-sensitive adhesive sheet according to the present embodiment, a pressure-sensitive adhesive layer 42 that does not contain microcapsules or thermally expandable particles is further provided on the pressure-sensitive adhesive layer 20. Thereby, the adhesive force of the adhesive 40 with respect to the member (for example, workpiece | work 50 in Fig.2 (a)) adhere | attached on the adhesive 40 can be improved.

  As the adhesive material 44 constituting the adhesive layer 42, the same material as the adhesive materials 14 and 22 shown in the first embodiment can be applied.

  The method for peeling the work adhered to the adherend using the pressure-sensitive adhesive according to the present embodiment can be performed in the same manner as the work peeling method according to the first embodiment shown in FIGS.

  As described above, according to the present embodiment, the first microcapsule dispersed in the adhesive material and melted by heat, and the release agent encapsulated in the microcapsule and reducing the adhesive strength of the adhesive material. A pressure-sensitive adhesive having a pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer, dispersed in the pressure-sensitive adhesive material, and thermally expandable particles, and the same Since the pressure-sensitive adhesive sheet is constituted, the pressure-sensitive adhesive can be easily peeled off by simply performing a heat treatment and leaving almost no residue on the desired one-side attachment surface.

  Moreover, since the 3rd adhesive layer which does not contain a microcapsule or a thermally expansible particle is provided on a 2nd adhesive layer, the adhesive force of an adhesive can be improved.

[Third Embodiment]
An adhesive and an adhesive sheet according to a third embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure similar to the adhesive and adhesive sheet by 1st and 2nd embodiment shown in FIG. 1 thru | or FIG. 4, and description is abbreviate | omitted or simplified.

  FIG. 5 is a schematic cross-sectional view showing the structure of the pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the present embodiment.

  An adhesive layer 12 a is formed on the separator 10. The pressure-sensitive adhesive layer 12 a is obtained by dispersing the heat-meltable microcapsules 18 enclosing the release agent 16 and the heat-expandable particles 46 in the pressure-sensitive adhesive material 14. An adhesive layer 20 is formed on the adhesive layer 12a. The pressure-sensitive adhesive layer 20 is obtained by dispersing thermally expandable particles 24 in a pressure-sensitive adhesive material 22. A separator 26 is formed on the pressure-sensitive adhesive layer 20. Thus, a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive 40 formed by laminating the two pressure-sensitive adhesive layers 12 a and 20 is sandwiched between the separators 10 and 26 is configured.

  The main feature of the pressure-sensitive adhesive sheet according to the present embodiment is that, in the pressure-sensitive adhesive sheet according to the first embodiment, thermally expandable particles 46 are further dispersed in the pressure-sensitive adhesive layer 12a in addition to the microcapsules 18.

  Dispersion of the heat-expandable particles 46 also in the pressure-sensitive adhesive layer 12a causes more cracks to be generated in the pressure-sensitive adhesive layer 12a by the heat-expandable particles 24 and 46 expanded by heating. The release agent is more easily diffused. As a result, a large amount of the release agent 16 comes into contact with the adherend surface, the peelability is improved, and the peeling work can be performed efficiently.

  As the thermally expandable particle 46, the same material as the thermally expandable particle 24 shown in the first embodiment can be applied. The thermally expandable particle 46 may be the same as the thermally expandable particle 24, but the thermal expansion start temperature of the thermally expandable particle 46 is higher than the thermal expansion start temperature of the thermally expandable particle 24 (for example, 5 ° C. or more). ) It is more preferable if it is low. As the thermally expandable particles 46 expand before the thermally expandable particles 24, the diffusion of the release agent 16 in the pressure-sensitive adhesive layer 12 proceeds to some extent by the thermally expandable particles 46. It can be expanded, and the diffusibility of the release agent 16 can be further enhanced.

  Further, the thermally expandable particles 46 assist the diffusion of the release agent 16 released from the microcapsules 18 at an initial stage. Is the thermal expansion start temperature of the thermally expandable particles 46 the same as the melting point of the microcapsules 18? A slightly higher degree is desirable.

  The method for peeling the work adhered to the adherend using the pressure-sensitive adhesive according to the present embodiment can be performed in the same manner as the work peeling method according to the first embodiment shown in FIGS.

  As described above, according to the present embodiment, the first microcapsule dispersed in the adhesive material and melted by heat, and the release agent encapsulated in the microcapsule and reducing the adhesive strength of the adhesive material. A pressure-sensitive adhesive having a pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer, dispersed in the pressure-sensitive adhesive material, and thermally expandable particles, and the same Since the pressure-sensitive adhesive sheet is constituted, the pressure-sensitive adhesive can be easily peeled off by simply performing a heat treatment and leaving almost no residue on the desired one-side attachment surface.

  Moreover, the diffusibility of the mold release agent released from the microcapsules can be improved by including thermally expandable particles that expand due to heat in the first pressure-sensitive adhesive layer. Thereby, it is possible to improve the peelability and further suppress the generation of residues.

[Fourth Embodiment]
The pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to the fourth embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the structure similar to the adhesive and adhesive sheet by 1st thru | or 3rd embodiment shown in FIG. 1 thru | or FIG. 5, and description is abbreviate | omitted or simplified.

  FIG. 6 is a schematic cross-sectional view showing the structure of the pressure-sensitive adhesive and pressure-sensitive adhesive sheet according to this embodiment.

  An adhesive layer 12 b is formed on the separator 10. The pressure-sensitive adhesive layer 12 b is obtained by dispersing heat-meltable microcapsules 18 enclosing the release agent 16 and the thermally expandable particles 48 in the pressure-sensitive adhesive material 14. An adhesive layer 20 is formed on the adhesive layer 12b. The pressure-sensitive adhesive layer 20 is obtained by dispersing thermally expandable particles 24 in a pressure-sensitive adhesive material 22. A separator 26 is formed on the pressure-sensitive adhesive layer 20. Thus, a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive 40 formed by laminating the two pressure-sensitive adhesive layers 12b and 20 is sandwiched between the separators 10 and 26 is configured.

  The main feature of the pressure-sensitive adhesive sheet according to the present embodiment is that, in the pressure-sensitive adhesive sheet according to the first embodiment, the microcapsule 18 further includes thermally expandable particles 48 in addition to the release agent 16.

  By encapsulating the thermally expandable particles 48 in the microcapsule 18, the microcapsule 18 is physically ruptured by the thermally expandable particles 48 expanded by heating, and more cracks are generated. Oozes out easily. As a result, a large amount of the release agent 16 comes into contact with the adherend surface, the peelability is improved, and the peeling work can be performed efficiently.

  As the thermally expandable particles 48, the same material as the thermally expandable particles 24 shown in the first embodiment can be applied. The thermally expandable particle 48 may be the same as the thermally expandable particle 24, but the thermal expansion start temperature of the thermally expandable particle 48 is higher than the thermal expansion start temperature of the thermally expandable particle 24 (for example, 5 ° C. or more). ) It is more preferable if it is low. As the thermally expandable particles 48 expand before the thermally expandable particles 24, the diffusion of the release agent 16 in the pressure-sensitive adhesive layer 12 proceeds to some extent by the thermally expandable particles 48. It can be expanded, and the diffusibility of the release agent 16 can be further enhanced.

  Further, it is desirable that the thermal expansion start temperature of the thermally expandable particles 48 is the same as or slightly higher than the melting point of the microcapsule 18. The thermally expandable particle 48 assists the diffusion of the release agent 16 released from the microcapsule 18 at an initial stage and promotes the destruction of the microcapsule 18 from the inside. From the viewpoint of promoting the destruction of the microcapsules 18, it is desirable that the thermally expandable particles 48 expand after the microcapsules 18 start to melt. In that sense, it is extremely effective to set the thermal expansion start temperature of the thermally expandable particles 48 to a temperature several degrees higher than the melting point of the microcapsules 18.

  The thermally expandable particles 48 may be included in all the microcapsules 18 or may be included in some of the microcapsules 18.

  The method for peeling the work adhered to the adherend using the pressure-sensitive adhesive according to the present embodiment can be performed in the same manner as the work peeling method according to the first embodiment shown in FIGS.

  As described above, according to the present embodiment, the first microcapsule dispersed in the adhesive material and melted by heat, and the release agent encapsulated in the microcapsule and reducing the adhesive strength of the adhesive material. A pressure-sensitive adhesive having a pressure-sensitive adhesive layer, a second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer, dispersed in the pressure-sensitive adhesive material, and thermally expandable particles, and the same Since the pressure-sensitive adhesive sheet is constituted, the pressure-sensitive adhesive can be easily peeled off by simply performing a heat treatment and leaving almost no residue on the desired one-side attachment surface.

  Further, by encapsulating thermally expandable particles that expand due to heat in the microcapsules in the first pressure-sensitive adhesive layer, the destruction of the microcapsules is promoted, and the diffusibility of the release agent released from the microcapsules is increased. Can be improved. Thereby, it is possible to improve the peelability and further suppress the generation of residues.

[Modified Embodiment]
The present invention is not limited to the above embodiment, and various modifications can be made.

  For example, in the third and fourth embodiments, in the pressure-sensitive adhesive composed of two pressure-sensitive adhesive layers, the thermally expandable particles 46 and 48 are added to the pressure-sensitive adhesive layers 12a and 12b containing the microcapsule 18. In the adhesive composed of the three adhesive layers as shown in the second embodiment, the heat-expandable particles 46 and 48 may be added to the adhesive material layer 12 containing the microcapsule 18.

  In the first, third and fourth embodiments, an adhesive composed of two adhesive layers is shown. In the second embodiment, an adhesive composed of three adhesive layers is shown. You may comprise the adhesive which consists of an agent layer.

  In the third embodiment, the heat-expandable particles 46 are dispersed in the adhesive material 14. In the fourth embodiment, the heat-expandable particles 48 are encapsulated in the microcapsule 18. While being dispersed in the material 14, the thermally expandable particles 48 may be included in the microcapsules 18.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, of course, it is not limited to these.

[Example 1]
80 parts by weight of a fluorine-modified silicone oil (manufactured by Shiwa Sangyo Co., Ltd., FS 1265 1000 CS) was added to 180 parts by weight of a 4% aqueous solution of ethylene-maleic anhydride copolymer adjusted to pH 6.0, and the homogenizer After emulsifying with this, the emulsion was heated to 60 ° C.

  Next, 20 parts by weight of melamine is added to 40 parts by weight of 40% formaldehyde aqueous solution, and a prepolymer aqueous solution obtained by reacting at 60 ° C. for 15 minutes is dropped into the emulsion, and 0.1N hydrochloric acid is added while stirring. The pH was adjusted to 5.3 by dropwise addition. And it heated up to 80 degreeC and stirred at the stirring speed of 10000 rpm for 1 hour. Subsequently, 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5, and the mixture was further stirred for 3 hours and then cooled to obtain a microcapsule dispersion containing a release agent having an average particle size of 10 μm. The melting point of the shell material of the microcapsule was about 100 ° C. as measured by DSC.

  Next, this dispersion was filter-pressed and air-dried to produce powdery microcapsules.

  Next, 30 parts by weight of powdered microcapsules were mixed with 100 parts by weight of an acrylic pressure-sensitive adhesive, and applied to one side of a 100 μm thick polyester film to form a pressure-sensitive adhesive layer containing 15 μm thick microcapsules.

  The weight ratio of the release agent to the pressure-sensitive adhesive layer was 8 wt%.

  Separately, 600 g of ion-exchange water, 150 g of sodium chloride, 1.5 g of adipic acid-diethanolamine condensate, and 40 g of colloidal silica 20% aqueous solution are mixed, and the pH is adjusted to 3.7 to 4.1 with sulfuric acid. Was the aqueous phase.

  Next, 180 g of acrylonitrile, 105 g of methacrylonitrile, 15 g of methyl methacrylate, 1.5 g of ethylene glycol dimethacrylate, 2.0 g of polyoxyethylene nonylphenyl ether acrylate, 75 g of isopentane, and 1 g of azobisisobutyronitrile are mixed and stirred. This was dissolved to obtain an oil phase.

  Next, the aqueous phase and the oil phase prepared as described above were mixed, and stirred with a TK homomixer at a stirring speed of 20000 rpm for 5 minutes to obtain a suspension.

  Next, this suspension was transferred to a 1.5 L pressure reactor and purged with nitrogen, and then reacted at 70 ° C. for 15 hours with stirring.

  Next, the obtained reaction product was filtered and dried to obtain thermally expandable particles having an average particle diameter of 10 μm. The thermal expansion start temperature of the thermally expandable particles thus formed was 110 ° C.

  Next, on the pressure-sensitive adhesive layer containing microcapsules, a pressure-sensitive adhesive layer prepared by mixing 30 parts by weight of the thermally expandable particles with 100 parts by weight of an acrylic pressure-sensitive adhesive is applied at a thickness of 15 μm, and contains heat-expandable particles. A pressure-sensitive adhesive layer was formed.

  The weight ratio of the thermally expandable particles to the pressure-sensitive adhesive layer was 8 wt%.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Example 2]
In the same manner as in the method for producing the pressure-sensitive adhesive sheet of Example 1, a pressure-sensitive adhesive layer containing a 15 μm-thick microcapsule on a 100 μm-thick polyester film and a pressure-sensitive adhesive containing 15 μm-thick thermally expandable particles Layers were formed.

  Next, an acrylic pressure-sensitive adhesive was applied on the pressure-sensitive adhesive layer containing the heat-expandable particles thus formed to form a pressure-sensitive adhesive layer having a thickness of 10 μm.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of three pressure-sensitive adhesive layers was produced.

[Example 3]
In the pressure-sensitive adhesive sheet of Example 1, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the thermal expansion start temperature of the thermally expandable particles was adjusted to 115 ° C.

[Example 4]
In the same manner as in the method for producing the pressure-sensitive adhesive sheet of Example 1, powdery macrocapsules having an average particle diameter of 10 μm enclosing a release agent, and thermally expandable particles having an average particle diameter of 10 μm having a thermal expansion start temperature of 100 ° C. Formed.

  Next, 30 parts by weight of powdery microcapsules and 10 parts by weight of thermally expandable particles are mixed in 90 parts by weight of an acrylic pressure-sensitive adhesive, and applied to one side of a 100 μm thick polyester film. The containing adhesive layer was formed.

  The weight ratio of the microcapsules to the pressure-sensitive adhesive layer was 8 wt%, and the weight ratio of the thermally expandable particles was 4 wt%.

  Next, an adhesive layer containing thermally expandable particles was formed in the same manner as in Example 1 on the adhesive layer containing the microcapsules and thermally expandable particles thus formed.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Example 5]
80 parts by weight of a fluorine-modified silicone oil (manufactured by Shiwa Sangyo Co., Ltd., FS 1265 1000 CS) was added to 180 parts by weight of a 4% aqueous solution of ethylene-maleic anhydride copolymer adjusted to pH 6.0, and the homogenizer After the emulsification, a thermally expandable particle (thermal expansion start temperature: 100 ° C., average particle diameter: 2 μm) prepared in the same manner as in Example 1 except that the stirring speed of Example 1 was changed from 10,000 rpm to 50000 rpm. ) 100 parts by weight were mixed and dispersed, and the emulsion was heated to 60 ° C.

  Next, 20 parts by weight of melamine is added to 40 parts by weight of 40% formaldehyde aqueous solution, and a prepolymer aqueous solution obtained by reacting at 60 ° C. for 15 minutes is dropped into the emulsion, and 0.1N hydrochloric acid is added while stirring. The pH was adjusted to 5.3 by dropwise addition. And it heated up to 80 degreeC and stirred for 1 hour. Subsequently, 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5, and the mixture was further stirred for 3 hours and then cooled to disperse microcapsules having an average particle diameter of 10 μm containing thermally expanded particles and a release agent. A liquid was obtained. The melting point of the shell material of the microcapsule was about 100 ° C. as measured by DSC.

  Next, this dispersion was filter-pressed and air-dried to produce powdery microcapsules containing thermally expandable particles and a release agent.

  Next, 30 parts by weight of powdered microcapsules were mixed with 100 parts by weight of an acrylic pressure-sensitive adhesive, and applied to one side of a 100 μm thick polyester film to form a pressure-sensitive adhesive layer containing 15 μm thick microcapsules.

  The weight ratio of the release agent to the pressure-sensitive adhesive layer was 8 wt%.

  Next, a pressure-sensitive adhesive layer containing thermally expandable particles was formed on the pressure-sensitive adhesive layer containing the microcapsules thus formed in the same manner as in Example 1.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Example 6]
In the pressure-sensitive adhesive sheet of Example 5, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 5 except that the thermal expansion start temperature of the thermally expandable particles included in the microcapsules was changed to 103 ° C.

[Example 7]
In the pressure-sensitive adhesive sheet of Example 1, the pressure-sensitive adhesive layer was adhered in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer containing microcapsules was changed to 13 μm (1.3 times the average particle size of the microcapsules). A sheet was produced.

[Example 8]
In the pressure-sensitive adhesive sheet of Example 1, the pressure-sensitive adhesive layer was adhered by the same method as in Example 1 except that the thickness of the pressure-sensitive adhesive layer containing microcapsules was changed to 18 μm (1.8 times the average particle diameter of the microcapsules). A sheet was produced.

[Comparative Example 1]
80 parts by weight of fluorine-modified silicone oil (manufactured by Shiwa Sangyo Co., Ltd., FS 1265 1000 CS) was added to 180 parts by weight of a 4% aqueous solution of ethylene-maleic anhydride copolymer adjusted to pH 6.0, and homogenizer. After emulsifying with this, the emulsion was heated to 50 ° C.

  Next, 20 parts by weight of melamine is added to 40 parts by weight of 40% formaldehyde aqueous solution, and a prepolymer aqueous solution obtained by reacting at 50 ° C. for 10 minutes is dropped into the emulsion, and 0.1N hydrochloric acid is added while stirring. The pH was adjusted to 5.3 by dropwise addition. And it heated up to 70 degreeC and stirred at the stirring speed of 10000 rpm for 0.5 hour. Subsequently, 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5, and the mixture was further stirred for 3 hours and then cooled to obtain a microcapsule dispersion containing a release agent having an average particle size of 10 μm. The melting point of the shell material of the microcapsule was about 55 ° C. as measured by DSC.

  Next, this dispersion was filter-pressed and air-dried to produce powdery microcapsules.

  Next, 30 parts by weight of powdered microcapsules were mixed with 100 parts by weight of an acrylic pressure-sensitive adhesive, and applied to one side of a 100 μm thick polyester film to form a pressure-sensitive adhesive layer containing 15 μm thick microcapsules.

  The weight ratio of the release agent to the pressure-sensitive adhesive layer was 8 wt%.

  Next, a pressure-sensitive adhesive layer containing thermally expandable particles was formed on the pressure-sensitive adhesive layer containing the microcapsules thus formed in the same manner as in Example 1.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Comparative Example 2]
80 parts by weight of fluorine-modified silicone oil (manufactured by Shiwa Sangyo Co., Ltd., FS 1265 1000 CS) was added to 180 parts by weight of a 4% aqueous solution of ethylene-maleic anhydride copolymer adjusted to pH 6.0, and homogenizer. After emulsifying with this, the emulsion was heated to 60 ° C.

  Next, 20 parts by weight of melamine was added to 40 parts by weight of 40% formaldehyde aqueous solution, and a prepolymer aqueous solution obtained by reacting at 60 ° C. for 10 minutes was dropped into the emulsion, and 0.1N hydrochloric acid was added while stirring. The pH was adjusted to 5.3 by dropwise addition. And it heated up to 85 degreeC and stirred at the stirring speed of 10000 rpm for 1.5 hours. Subsequently, 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5, and the mixture was further stirred for 3 hours and then cooled to obtain a microcapsule dispersion containing a release agent having an average particle size of 10 μm. The melting point of the shell material of this microcapsule was about 155 ° C. as measured by DSC.

  Next, this dispersion was filter-pressed and air-dried to produce powdery microcapsules.

  Next, 30 parts by weight of powdered microcapsules were mixed with 100 parts by weight of an acrylic pressure-sensitive adhesive, and applied to one side of a 100 μm thick polyester film to form a pressure-sensitive adhesive layer containing 15 μm thick microcapsules.

  The weight ratio of the release agent to the pressure-sensitive adhesive layer was 8 wt%.

  Next, a pressure-sensitive adhesive layer containing thermally expandable particles was formed on the pressure-sensitive adhesive layer containing the microcapsules thus formed in the same manner as in Example 1.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Comparative Example 3]
In the method for producing the pressure-sensitive adhesive sheet of Example 1, the mixing ratio of the powdered microcapsules and the acrylic pressure-sensitive adhesive was manipulated to form a pressure-sensitive adhesive layer in which the weight ratio of the release agent to the pressure-sensitive adhesive layer was 0.5 wt%. did.

  Next, a pressure-sensitive adhesive layer containing thermally expandable particles was formed on the pressure-sensitive adhesive layer containing the microcapsules thus formed in the same manner as in Example 1.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Comparative Example 4]
In the method for producing the pressure-sensitive adhesive sheet of Example 1, the mixing ratio of the powdery microcapsules and the acrylic pressure-sensitive adhesive was manipulated to form a pressure-sensitive adhesive layer in which the weight ratio of the release agent to the pressure-sensitive adhesive layer was 21 wt%.

  Next, a pressure-sensitive adhesive layer containing thermally expandable particles was formed on the pressure-sensitive adhesive layer containing the microcapsules thus formed in the same manner as in Example 1.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Comparative Example 5]
In the production method of the pressure-sensitive adhesive sheet of Example 1, microcapsules encapsulating a release agent having an average particle size of 0.5 μm by changing the stirring conditions of the emulsion in which the prepolymer aqueous solution is dropped to 30000 rpm for 1 hour A dispersion was obtained.

  Next, this dispersion was filter-pressed and air-dried to produce powdery microcapsules.

  Next, 30 parts by weight of powdery microcapsules are mixed with 100 parts by weight of an acrylic pressure-sensitive adhesive and applied to one side of a 100 μm thick polyester film to form a pressure-sensitive adhesive layer containing 0.75 μm thick microcapsules. did.

  The weight ratio of the release agent to the pressure-sensitive adhesive layer was 8 wt%.

  Next, a pressure-sensitive adhesive layer containing thermally expandable particles was formed on the pressure-sensitive adhesive layer containing the microcapsules thus formed in the same manner as in Example 1.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Comparative Example 6]
In the production method of the pressure-sensitive adhesive sheet of Example 1, the microcapsule dispersion containing the release agent having an average particle diameter of 55 μm by changing the stirring condition of the emulsion in which the prepolymer aqueous solution was dropped to 2000 rpm for 1 hour Got.

  Next, this dispersion was filter-pressed and air-dried to produce powdery microcapsules.

  Next, 30 parts by weight of powdery microcapsules were mixed with 100 parts by weight of an acrylic pressure-sensitive adhesive and applied to one side of a polyester film having a thickness of 100 μm to form a pressure-sensitive adhesive layer containing microcapsules having a thickness of 85 μm.

  The weight ratio of the release agent to the pressure-sensitive adhesive layer was 8 wt%.

  Next, a pressure-sensitive adhesive layer containing thermally expandable particles was formed on the pressure-sensitive adhesive layer containing the microcapsules thus formed in the same manner as in Example 1.

  Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive composed of two layers of pressure-sensitive adhesive layers was produced.

[Comparative Example 7]
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the thermal expansion start temperature of the thermally expandable particles used in Example 1 was adjusted to 75 ° C.

[Comparative Example 8]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the thermal expansion start temperature of the thermally expandable particles used in Example 1 was adjusted to 210 ° C.

[Comparative Example 9]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the thermally expandable particles used in Example 1 were adjusted to contain 0.5 wt% with respect to the pressure-sensitive adhesive layer.

[Comparative Example 10]
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the heat-expandable particles used in Example 1 were adjusted to contain 21 wt% with respect to the pressure-sensitive adhesive layer.

[Comparative Example 11]
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the average particle diameter of the thermally expandable particles used in Example 1 was adjusted to 0.5 μm.

[Comparative Example 12]
The pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the average particle size of the thermally expandable particles used in Example 1 was adjusted to 55 μm and the thickness of the pressure-sensitive adhesive layer containing the thermally expandable particles was adjusted to 85 μm. Produced.

[Comparative Example 13]
In the pressure-sensitive adhesive sheet of Example 1, the pressure-sensitive adhesive layer was adhered by the same method as in Example 1 except that the thickness of the pressure-sensitive adhesive layer containing microcapsules was changed to 10 μm (1.0 times the average particle diameter of the microcapsules). A sheet was produced.

[Comparative Example 14]
In the pressure-sensitive adhesive sheet of Example 1, the pressure-sensitive adhesive layer was adhered by the same method as in Example 1 except that the thickness of the pressure-sensitive adhesive layer containing microcapsules was changed to 20 μm (2.0 times the average particle size of the microcapsules). A sheet was produced.

[Comparative Example 15]
A pressure-sensitive adhesive sheet composed of a single pressure-sensitive adhesive layer containing the same thermally expandable particles as in Example 1 was produced. The thermal expansion start temperature of the thermally expandable particles was 110 ° C., the particle size was 10 μm, and the content ratio with respect to the adhesive layer was 8 wt%.

[Comparative Example 16]
A pressure-sensitive adhesive sheet comprising a single pressure-sensitive adhesive layer containing microcapsules encapsulating the same release agent as in Example 1 was produced. The melting point of the shell material of the microcapsule was 100 ° C., the particle size was 10 μm, and the content ratio to the pressure-sensitive adhesive layer was 8 wt%.

  Table 1 summarizes the preparation conditions of the samples of Examples 1 to 4 and Comparative Examples 1 to 12.

次に、実施例１〜８、比較例１〜１６の試料について、接着力及び剥離後の残渣の評価を行った。

Next, the adhesive strength and the residue after peeling were evaluated for the samples of Examples 1 to 8 and Comparative Examples 1 to 16.

  The adhesive strength at room temperature was measured by performing a 180 ° peel test at room temperature (25 ° C.) in accordance with JlSZ0237 using a stainless steel plate (SUS 304, BA finished surface) as an adherend. The measurement was performed immediately after adhesion and 30 days after adhesion.

  The adhesive strength after the heat treatment was set at an oven temperature of 110 ° C. and 160 ° C., left for 10 minutes under the heat treatment conditions, then removed from the oven, the test plate was returned to room temperature, and 180 ° C. as described above. ° Measured by performing a peel test.

  Evaluation of the residue after peeling evaluated the area of the residue on the stainless plate which is a to-be-adhered body using the optical microscope. Specifically, after taking a photograph with a microscope, the area of the residue was obtained by an image analyzer, and the area of the residue (residue rate [%]) was calculated.

  Table 2 summarizes the measurement results of adhesive strength and residue.

表２に示すように、実施例１〜８の粘着剤は、室温において高い接着力を示し、加熱後には高い剥離性と被着体にほとんど残渣が見られない良好な残渣率を有することが判った。粘着後３０日経過後の接着力にも変化は見られなかった。

As shown in Table 2, the pressure-sensitive adhesives of Examples 1 to 8 have high adhesive strength at room temperature, and have high releasability and a good residue rate in which almost no residue is found on the adherend. understood. There was no change in the adhesive strength after 30 days from the adhesion.

  The pressure-sensitive adhesive of Example 2 has a higher adhesive force than that of other examples. This is because a pressure-sensitive adhesive layer not containing microcapsules or heat-expandable particles is provided between the pressure-sensitive adhesive layer containing thermally expandable particles and the workpiece.

  The pressure-sensitive adhesive of Example 3 has a high foaming temperature of the thermally expanded particles, so that sufficient peelability is not obtained by heating at 110 ° C., but by heating at 160 ° C. than in Examples 1, 2, and 4. High peelability could be realized. This is because the temperature difference between the melting point of the microcapsules and the foaming temperature of the thermally expandable particles is increased from 10 ° C. to 15 ° C. in Example 1 or the like, so that the release agent is sufficiently oozed out during heating at the time of peeling. This is because the adhesive layer is cracked by the expansion of the heat-expandable particles after that, so that the diffusibility of the release agent is improved and it becomes easier to peel off.

  The pressure-sensitive adhesive of Example 4 was able to reduce the adhesive strength after heating at a low temperature (110 ° C.) as compared with Examples 1 and 2. This is because cracks are generated by the pressing force caused by the expansion of the thermally expandable particles in the lower pressure-sensitive adhesive layer, and the diffusion of the release agent is promoted.

  The adhesives of Examples 5 and 6 have higher peelability than those of Examples 1 to 4. This is because the heat-expandable particles in the microcapsule promote the destruction of the microcapsule and thus promote the diffusion of the release agent. In particular, in the pressure-sensitive adhesive of Example 6 where the foaming temperature of the thermally expandable particles is high, the thermally expandable particles expand and crack after the release agent has sufficiently oozed out, so that the diffusibility of the release agent is further increased. Improved, easier to peel off and less residue.

  On the other hand, when the pressure-sensitive adhesive of Comparative Example 1 is allowed to stand at room temperature for 30 days after the pressure-sensitive adhesive, the adhesive strength decreases. This is because the melting point of the microcapsule is as low as 55 ° C., so that the release agent oozes out from the microcapsule over time.

  On the contrary, the pressure-sensitive adhesive of Comparative Example 2 has a high adhesive force at room temperature, but the adhesive force does not decrease even after heating. This is because the melting point of the microcapsule is as high as 155 ° C., and it is considered that the same result as in Example 1 is exhibited if the heating temperature is further increased. However, it is considered that the melting point of the microcapsules is preferably set to about 150 ° C. or less in consideration of the actual usage pattern.

  In the pressure-sensitive adhesive of Comparative Example 3, the adhesive strength does not decrease even after heating. This is because the amount of the release agent with respect to the pressure-sensitive adhesive material is small, and the adhesive force of the pressure-sensitive adhesive layer cannot be sufficiently reduced.

  The pressure-sensitive adhesive of Comparative Example 4 has a high adhesive force at room temperature and a high releasability by heating. However, since the content of the release agent is too large, the adherend is contaminated by the release agent. It was.

  The pressure-sensitive adhesive of Comparative Example 5 does not have a reduced adhesive force even after heating. This is because the particle size of the microcapsules is small, so that the amount of the release agent remaining in the microcapsules after the microcapsules are melted, and the adhesive force of the pressure-sensitive adhesive layer cannot be sufficiently reduced. Conceivable.

  The pressure-sensitive adhesive of Comparative Example 6 had higher peelability after heating than that of Example 1, but the adhesive strength at room temperature was not sufficient. This is presumably because the adhesive strength of the pressure-sensitive adhesive layer is reduced because the microcapsule has a large particle size and the proportion of the microcapsule in the pressure-sensitive adhesive layer is high.

  In the pressure-sensitive adhesive of Comparative Example 7, the adhesive strength is greatly reduced as compared with Example 1 when left for 30 days at room temperature after the pressure-sensitive adhesive. This is presumably because the expansion temperature of the thermally expandable particles is as low as 75 ° C., so that the thermally expandable particles naturally expand with the passage of time and lower the adhesive force.

  The pressure-sensitive adhesive of Comparative Example 8 has a high adhesive force at room temperature, but the adhesive force does not decrease even after heating. This is because the foaming temperature of the thermally expandable particles is as high as 210 ° C., and it is considered that the same result as in Example 1 is exhibited if the heating temperature is further increased. However, considering the actual usage pattern, it is considered desirable to set the foaming temperature of the thermally expandable particles to about 200 ° C. or less.

  Since the pressure-sensitive adhesive of Comparative Example 9 had a too low mixing ratio of the heat-expandable particles, the adhesive strength was large even after heating, and there were many residues after peeling.

  On the contrary, the adhesive of Comparative Example 10 had a too high mixing ratio of the heat-expandable particles, so that the adhesive strength of the adhesive layer at room temperature was reduced.

  In the pressure-sensitive adhesive of Comparative Example 11, since the average particle diameter of the thermally expandable particles was too small, the adhesive strength after heating hardly decreased, the peelability was poor, and there were many residues.

  In the pressure-sensitive adhesive of Comparative Example 12, since the average particle diameter of the thermally expandable particles was too large, the adhesive strength of the pressure-sensitive adhesive layer at room temperature was reduced.

  In the pressure-sensitive adhesive of Comparative Example 13, since the thickness of the pressure-sensitive adhesive layer is almost equal to the average particle diameter of the microcapsules, the contact area between the pressure-sensitive adhesive material and the adherend is not sufficient, and the adhesive strength of the pressure-sensitive adhesive layer at room temperature is Declined.

  On the contrary, the pressure-sensitive adhesive of Comparative Example 14 has a layer thickness of the pressure-sensitive adhesive layer as large as twice or more the average particle diameter of the microcapsules, so that the release agent does not spread sufficiently in the pressure-sensitive adhesive layer, The adhesive strength could not be sufficiently reduced.

  The pressure-sensitive adhesive of Comparative Example 15 does not contain a release agent and weakens the adhesive force only by the pressing force when the thermally expandable particles expand. The adhesive force after heating cannot be sufficiently reduced, and there are many residues. It was.

  The pressure-sensitive adhesive of Comparative Example 16 contained microcapsules containing a release agent, but did not contain heat-expandable particles, so that the peelability was not improved and there were many residues.

  As detailed above, the characteristics of the present invention are summarized as follows.

(Supplementary Note 1) First adhesive material, microcapsules dispersed in the first adhesive material and melted by heat, and release agent encapsulated in the microcapsule to reduce the adhesive strength of the adhesive material A first pressure-sensitive adhesive layer having
A second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer and having a second pressure-sensitive adhesive material and first thermally expandable particles that are dispersed in the second pressure-sensitive adhesive material and expand by heat. And a pressure-sensitive adhesive.

(Appendix 2) In the adhesive described in Appendix 1,
The pressure-sensitive adhesive further comprises a third pressure-sensitive adhesive layer made of a third pressure-sensitive adhesive material formed on the second pressure-sensitive adhesive layer.

(Additional remark 3) In the adhesive of Additional remark 1 or 2,
The pressure-sensitive adhesive is characterized in that the foaming temperature of the first thermally expandable particles is higher than the melting point of the microcapsules.

(Appendix 4) In the adhesive according to any one of appendices 1 to 3,
The first pressure-sensitive adhesive layer further has second thermally expandable particles dispersed in the first pressure-sensitive adhesive material and expanded by heat.

(Appendix 5) In the adhesive described in Appendix 4,
The pressure-sensitive adhesive is characterized in that the foaming temperature of the second thermally expandable particles is lower than the foaming temperature of the first thermally expandable particles.

(Appendix 6) In the adhesive according to Appendix 4 or 5,
The foaming temperature of the second thermally expandable particles is equal to or higher than the melting point of the microcapsule.

(Appendix 7) In the adhesive according to any one of appendices 1 to 6,
The pressure-sensitive adhesive further comprising third thermally expandable particles encapsulated in the microcapsule and expanded by heat.

(Appendix 8) In the adhesive described in Appendix 7,
The pressure-sensitive adhesive is characterized in that the foaming temperature of the third thermally expandable particles is lower than the foaming temperature of the first thermally expandable particles.

(Additional remark 9) In the adhesive of Additional remark 7 or 8,
The foaming temperature of said 3rd thermally expansible particle is more than melting | fusing point of the said microcapsule. The adhesive characterized by the above-mentioned.

(Appendix 10) In the adhesive according to any one of appendices 1 to 9,
The pressure-sensitive adhesive is characterized in that the melting point of the microcapsule is 60 to 150 ° C.

(Appendix 11) In the adhesive according to any one of appendices 1 to 10,
The average particle size of the microcapsules is 1 to 50 μm.

(Appendix 12) In the adhesive according to any one of appendices 1 to 11,
The said mold release agent is contained in the ratio of 1-20 wt% with respect to a said 1st adhesive material. The adhesive characterized by the above-mentioned.

(Appendix 13) In the adhesive according to any one of appendices 1 to 12,
The foaming temperature of said 1st thermally expansible particle is 80-200 degreeC. The adhesive characterized by the above-mentioned.

(Appendix 14) In the adhesive according to any one of appendices 1 to 13,
The first heat-expandable particles are contained in a proportion of 1 to 20 wt% with respect to the second adhesive material.

(Appendix 15) In the adhesive according to any one of appendices 1 to 14,
The first pressure-sensitive adhesive layer is provided in contact with the adherend.

(Supplementary Note 16) An adhesive sheet in which an adhesive is formed on a substrate,
The adhesive is
A first pressure-sensitive adhesive material, a microcapsule dispersed in the first pressure-sensitive adhesive material and melted by heat, and a release agent encapsulated in the microcapsule and reducing the pressure-sensitive adhesive force of the pressure-sensitive adhesive material. 1 adhesive layer;
A second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer and having a second pressure-sensitive adhesive material and first thermally expandable particles that are dispersed in the second pressure-sensitive adhesive material and expand by heat. A pressure-sensitive adhesive sheet comprising:

(Appendix 17) In the adhesive sheet described in Appendix 16,
The pressure-sensitive adhesive sheet further comprises a third pressure-sensitive adhesive layer made of a third pressure-sensitive adhesive material formed on the second pressure-sensitive adhesive layer.

(Appendix 18) In the adhesive sheet according to Appendix 16 or 17,
The pressure-sensitive adhesive sheet, wherein the first pressure-sensitive adhesive layer further includes second thermally expandable particles dispersed in the first pressure-sensitive adhesive material and expanded by heat.

(Supplementary note 19) In the pressure-sensitive adhesive sheet according to any one of supplementary notes 16 to 18,
The pressure-sensitive adhesive sheet further comprising third thermally expandable particles encapsulated in the microcapsule and expanded by heat.

(Supplementary Note 20) A first pressure-sensitive adhesive material, a microcapsule dispersed in the first pressure-sensitive adhesive material and melted by heat, and an adhesive force of the pressure-sensitive adhesive material on the adherend. Formed on the first pressure-sensitive adhesive layer, dispersed in the second pressure-sensitive adhesive material, and expanded by heat. A method of peeling a workpiece pasted using an adhesive having a second adhesive layer having thermally expandable particles,
By performing a heat treatment, the microcapsule is melted and the thermally expandable particles are expanded, and the release agent is diffused into the first adhesive material to reduce the adhesive force. Peeling method.

It is a schematic sectional drawing which shows the structure of the adhesive and adhesive sheet by 1st Embodiment of this invention. It is a figure (the 1) explaining the peeling method of the workpiece | work by 1st Embodiment of this invention. It is FIG. (2) explaining the peeling method of the workpiece | work by 1st Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the adhesive and adhesive sheet by 2nd Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the adhesive and adhesive sheet by 3rd Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the adhesive and adhesive sheet by 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 26 ... Separator 12, 12a, 12b, 20, 42 ... Adhesive layer 14, 22, 44 ... Adhesive material 16 ... Release agent 18 ... Microcapsule 24, 46, 48 ... Thermally expansible particle 30 ... Adhering body 40 ... Adhesive 50 ... Workpiece 60 ... Heating means

Claims (7)

A first pressure-sensitive adhesive material, a microcapsule dispersed in the first pressure-sensitive adhesive material and melted by heat, and a release agent encapsulated in the microcapsule and reducing the pressure-sensitive adhesive force of the pressure-sensitive adhesive material. 1 adhesive layer;
A second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer and having a second pressure-sensitive adhesive material and first thermally expandable particles that are dispersed in the second pressure-sensitive adhesive material and expand by heat. And a pressure-sensitive adhesive. The pressure-sensitive adhesive according to claim 1,
The pressure-sensitive adhesive further comprises a third pressure-sensitive adhesive layer made of a third pressure-sensitive adhesive material formed on the second pressure-sensitive adhesive layer. In the pressure-sensitive adhesive according to claim 1 or 2,
The pressure-sensitive adhesive is characterized in that the foaming temperature of the first thermally expandable particles is higher than the melting point of the microcapsules. In the adhesive according to any one of claims 1 to 3,
The first pressure-sensitive adhesive layer further has second thermally expandable particles dispersed in the first pressure-sensitive adhesive material and expanded by heat. In the adhesive according to any one of claims 1 to 4,
The pressure-sensitive adhesive further comprising third thermally expandable particles encapsulated in the microcapsule and expanded by heat. An adhesive sheet in which an adhesive is formed on a substrate,
The adhesive is
A first pressure-sensitive adhesive material, a microcapsule dispersed in the first pressure-sensitive adhesive material and melted by heat, and a release agent encapsulated in the microcapsule and reducing the pressure-sensitive adhesive force of the pressure-sensitive adhesive material. 1 adhesive layer;
A second pressure-sensitive adhesive layer formed on the first pressure-sensitive adhesive layer and having a second pressure-sensitive adhesive material and first thermally expandable particles that are dispersed in the second pressure-sensitive adhesive material and expand by heat. A pressure-sensitive adhesive sheet comprising: On the adherend, a first adhesive material, a microcapsule dispersed in the first adhesive material and melted by heat, and encapsulated in the microcapsule, are separated to reduce the adhesive strength of the adhesive material. A first pressure-sensitive adhesive layer having a mold, and a thermal expansion property formed on the first pressure-sensitive adhesive layer, dispersed in the second pressure-sensitive adhesive material, and the second pressure-sensitive adhesive material, and expanded by heat. A method for peeling a workpiece affixed using an adhesive having a second adhesive layer having particles,
By performing a heat treatment, the microcapsule is melted and the thermally expandable particles are expanded, and the release agent is diffused into the first adhesive material to reduce the adhesive force. Peeling method.

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