JP2008248065A - Adhesive and adhesive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive and an adhesive sheet using the same, excellent in initial tackiness and its holding capacity, facilitating peeling off an adherent when wanted to peel off, and also enabling the adhesive peel interface to be selected at discretion. <P>SOLUTION: The adhesive is composed of two layers, wherein one of the layers consists of a pressure-sensitive peel-type adhesive 1 including a releasant 3 and at least including pressure-breakable microcapsules 2, and the other consists of a heat-peel-type adhesive 4 including a second releasant 6 and at least including heat-breakable microcapsules 5. This adhesive is so designed that the pressure-breakable microcapsules 2 do not break at a break-setting temperature for the heat-breakable microcapsules 5, and the heat-breakable microcapsules 5 do not break at a break-setting pressure for the pressure-breakable microcapsules 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet, and in particular, has excellent adhesive strength, and is characterized by a structure for easily peeling from any adherend side by a specific treatment at any time. It is about.

The pressure-sensitive adhesive and the pressure-sensitive adhesive sheet provided on the substrate that supports the pressure-sensitive adhesive are used in a wide range of applications such as label sticking.
Applications of adhesives and adhesive sheets include temporary fixing of electronic parts on production lines and sticking of recycle labels. In such areas, electronic parts and labels are covered with adhesives or adhesive sheets. It is also required that it can be easily peeled off after being attached to the body.

From this 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, a heat-peelable pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer containing a foaming agent is provided on a substrate is disclosed (for example, see Patent Documents 1 to 4).
This is one in which the foaming agent in the pressure-sensitive adhesive layer is foamed to reduce the adhesive force and easily peel off from the adherend.

Moreover, the adhesive containing the microcapsule which included the mold release agent is disclosed (for example, refer patent document 5).
In this method, the microcapsules are destroyed by pressurization during peeling, and the adhesive strength of the pressure-sensitive adhesive is reduced by the release agent that exudes from the microcapsules.

Moreover, an easily peelable pressure-sensitive adhesive sheet in which thermally expandable particles are mixed in a pressure-sensitive adhesive is disclosed (for example, see Patent Document 6).
In this method, heating is performed when it is desired to peel off the adhesive tape, and the particles expand to widen the gap between the label and the adherend to facilitate peeling.
Japanese Patent Publication No. 51-024534 JP 56-061468 A JP-A-56-061469 JP 60-252681 A JP 09-095650 A Japanese Patent Laid-Open No. 11-228921

  However, in the pressure-sensitive adhesives described in Patent Documents 1 to 4, there is a limit to obtain a peeling force only by the foaming force of particles in the pressure-sensitive adhesive, and sufficient peelability is obtained after the foaming treatment. There is no problem.

  In addition, the pressure-sensitive adhesive described in Patent Document 6 has a problem that the gap between the label and the adherend is only physically widened, and the decrease in pressure-sensitive adhesive force is small so that it is difficult to peel off. There is a problem in that the label material is deteriorated due to excessive heating, which makes it difficult to peel off.

In particular, when recycling electrical products, it is necessary to sort by material.
At this time, since the label affixed to the housing is made of a material different from that of the housing, it is necessary to peel it off from the housing. This increases the number of recycling man-hours.

In addition, a great deal of labor has been required to remove labels attached to plastic and glass bottle recycling containers for reuse after use.
For this reason, there is a demand for an adhesive that can be easily peeled off when it is desired to peel it off.

  In addition, the adhesive tape used for temporarily fixing parts during assembly and polishing and cutting various electronic parts is strongly equipped with a function that can be easily removed from the adherend after use. It has been requested.

  In particular, with conventional adhesive tapes, it is unclear whether the adhesive remains at the interface between the part to be peeled off or the part to be peeled off. It was a problem.

  Accordingly, an object of the present invention is to have excellent initial adhesive force and holding force, facilitate peeling from an adherend when it is desired to peel off, and freely select an interface at which the pressure-sensitive adhesive peels.

FIG. 1 is an explanatory diagram of the principle configuration of the present invention, and means for solving the problems in the present invention will now be described with reference to FIG.
See FIG. 1 In order to solve the above-mentioned problem, the present invention provides a pressure-sensitive peelable pressure-sensitive adhesive 1 including a release agent 3 and at least a pressure-breaking microcapsule 2 that is pressure-breakable. And a heat-peelable pressure-sensitive adhesive 4 containing at least a heat-breakable microcapsule 5 that is encapsulated with a mold release agent 6 and is destroyed by heating. The pressure-breakable microcapsule 2 is a heat-breakable microcapsule 2. It is characterized in that it does not break at the breaking set temperature of the capsule 5 and that the heat breaking type microcapsule 5 does not break at the breaking set pressure of the pressure breaking type microcapsule 2.

  As described above, the pressure-sensitive adhesive 1 and the heat-peelable pressure-sensitive adhesive 4 have a two-layer structure. Can be selected, which can contribute to the efficiency of recycling.

  In this case, the breaking pressure of the pressure breaking type microcapsule 2 is set by appropriately adjusting the capsule membrane material, the capsule particle size, the capsule film thickness, and the like. On the other hand, the capsule may be broken. On the other hand, if it exceeds 5 MPa, it is difficult to provide a pressurizing means, and the base material itself may be damaged, so 1 MPa to 5 MPa is preferable.

Further, the melting point of the heat-breakable microcapsule 5 is the melting point of the capsule membrane material. If the melting point is less than 50 ° C., the microcapsule may be broken even during normal times, resulting in a decrease in adhesiveness. On the other hand, if the melting point exceeds 200 ° C., heating at about 200 ° C. is required for peeling, and the adherends 7 and 8 may be thermally deteriorated, so 50 to 200 ° C. is suitable.
The “melting point” as used in the present invention means a melting peak temperature when measured at a rate of temperature increase of 10 ± 1 ° C./min according to JISK7121 using a differential scanning calorimeter (DSC). To do.

  The heat destruction type microcapsule 5 in this case may be configured to be destroyed by applying a destruction set temperature under a pressure application condition that is equal to or lower than the destruction setting pressure of the pressure destruction type microcapsule 2, and is not intended. Even when heat equal to or higher than the destruction set temperature is applied, as long as no pressure is applied, peeling on the heat-peelable pressure-sensitive adhesive 4 side does not occur.

  Alternatively, the pressure destruction type microcapsule 2 may be configured to be destroyed by applying a failure setting pressure under a heating condition at a temperature equal to or lower than the destruction setting temperature of the heat destruction type microcapsule 5. Even when a pressure equal to or higher than the set pressure is applied, the separation on the pressure-sensitive release adhesive 1 side does not occur unless heat is applied.

  Further, the total amount of the release agent 3 that exudes from the pressure breakable microcapsule 2 in the pressure sensitive peelable adhesive 1 and the total amount of the release agent 6 that exudes from the heat destructible microcapsule 5 in the heat peelable adhesive 4. Are preferably the same amount, so that peeling at the selected peeling interface can be performed reliably.

  Further, it is desirable that the release agent 3 contained in the pressure breakable microcapsule 2 and the release agent 6 contained in the heat breakable microcapsule 5 are the same component, By using 6, the peeling interface does not depend on the type of the release agents 3 and 6.

  Further, the pressure-sensitive peelable pressure-sensitive adhesive 1 may be configured to include a plurality of types of pressure breakable microcapsules 2 having different breakage pressures, and the peeling phenomenon due to the release of the release agent 3 increases as the pressure increases. It will progress in stages.

  Alternatively, the heat-peelable pressure-sensitive adhesive 4 may be configured to include a plurality of types of heat-breakable microcapsules 5 made of shell materials having different melting points, and the peeling phenomenon due to the release of the mold release agent 6 increases the temperature. It will progress step by step.

  In this case, it is desirable that the pressure-sensitive release adhesive 1 and the heat release adhesive 4 contain 1 to 20 wt% of the release agents 3 and 6 in a weight ratio with respect to the base adhesive. When 3 and 6 are less than 1 wt% in the weight ratio with respect to the pressure-sensitive adhesive, there is no releasing effect. On the other hand, when the weight ratio exceeds 20 wt%, the pressure-sensitive adhesive component is reduced and sufficient adhesiveness cannot be obtained.

  In addition, it is desirable that the average particle size of the heat breakable microcapsule 5 and the pressure breakable microcapsule 2 is 1 to 50 μm, and the content of the release agents 3 and 6 is proportional to the cube of the particle size, When the average particle size is less than 1 μm, the release agents 3 and 6 are too small and the releasability is not sufficient, and when the average particle size exceeds 50 μm, the particle size is almost equal to the layer thickness of the adhesive. Since the microcapsules having no adhesive component occupy most of the pressure-sensitive adhesive layer, sufficient adhesiveness cannot be obtained.

  Moreover, the heat-breakable microcapsule 5 may contain thermally expandable microparticle spheres, and the peeling effect can be further improved.

The expansion temperature of the thermally expandable microparticle spheres is desirably 50 to 200 ° C. and desirably has a melting point within a range of ± 20 ° C. of the melting point of the shell of the heat-breaking microcapsule 5, It is more desirable to be within the range of ± 10 ° C.
Further, if the foaming temperature is less than 50 ° C., the heat-expandable microparticle spheres may be ruptured and the adhesiveness may be lowered even during normal times, and the foaming temperature of the heat-expandable microparticle spheres is 200 ° C. If it exceeds, heating at 200 ° C. or higher is required for peeling, and the adherends 7 and 8 are thermally deteriorated.

  Moreover, it is desirable that the base pressure-sensitive adhesive constituting the pressure-sensitive peelable pressure-sensitive adhesive 1 and the base pressure-sensitive adhesive constituting the heat-peelable pressure-sensitive adhesive 4 are the same component, and the base pressure-sensitive adhesives cause undesired reactions. In addition, the peeling effect by the release agents 3 and 6 having the same component can be made the same.

  As a pressure sensitive adhesive sheet using the above-mentioned pressure sensitive adhesive, a pressure sensitive peelable pressure sensitive adhesive layer made of a pressure sensitive peelable pressure sensitive adhesive 1 and a heat peelable pressure sensitive adhesive layer made of a heat peelable pressure sensitive adhesive 4 are directly in contact. Alternatively, the pressure-sensitive peelable pressure-sensitive adhesive layer and the heat-peelable pressure-sensitive adhesive layer may be configured to face each other with a substrate interposed therebetween.

  In this case, the pressure-sensitive peelable pressure-sensitive adhesive layer and the heat-peelable pressure-sensitive adhesive layer are made different from each other in at least one of hue, brightness, or saturation, so that the pressure-sensitive adhesive surface, and thus the pressure-sensitive adhesive layer can be adhered without causing an error. The sheet can be adhered to the adherends 7 and 8.

  A typical application example of such an adhesive or adhesive sheet is an electronic tag, and an adherend is applied by applying a preset pressure or heat to an electronic tag (RFID tag) that has finished a predetermined role. The electronic tag can be peeled without leaving an adhesive layer on the 7th and 8th sides.

  According to the present invention, since it has a layer containing microcapsules that breaks down by pressurization and exudes a release agent, and a layer containing microcapsules that breaks down by heating and exudes a release agent, means for pressurization or heating By selecting, the interface from which the pressure-sensitive adhesive peels can be freely selected, and the pressure-sensitive adhesive and the pressure-sensitive adhesive sheet can be easily peeled from the support.

  The pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention include a pressure-sensitive adhesive containing a microcapsule that encapsulates a release agent and is broken by pressurization, and a pressure-sensitive adhesive containing a microcapsule that is broken by heating. Since it consists of the apply | coated adhesive sheet, embodiment of this invention is described here with reference to FIG. 2 thru | or FIG.

FIG. 2 is a basic configuration diagram of the pressure-sensitive adhesive of the present invention, and comprises a two-layer structure of a pressure-sensitive peelable pressure-sensitive adhesive 10 and a heat-peelable pressure-sensitive adhesive 20.
The pressure-sensitive release adhesive 10 contains a release agent 13 therein and contains a microcapsule 12 having a predetermined melting point in the base adhesive 11 and selects a shell material or the like of the microcapsule 12. Therefore, the breaking pressure is set to 1 MPa to 5 MPa.

  On the other hand, the heat-peelable pressure-sensitive adhesive 20 includes a microcapsule 22 having a predetermined breaking pressure that encloses a release agent 23 in the base pressure-sensitive adhesive 21, and a shell material of the microcapsule 22 is selected. In this way, the melting point is 50 to 200 ° C.

  At this time, the melting point of the microcapsule 12 is set to be higher than the melting point of the microcapsule 22 and higher than the temperature applied for peeling, while the breaking pressure of the microcapsule 22 is higher than the breaking pressure of the microcapsule 12 and peeled. Therefore, it is necessary to set higher than the pressure to be applied.

See Figure 3
FIG. 3 is an explanatory diagram of the principle of selection of the release surface in the embodiment of the present invention. Here, in order to simplify the description, the microcapsule 12 contained in the pressure-sensitive release adhesive 10 is about 90 ° C. It is assumed that the microcapsules 22 contained in the heat-peelable pressure-sensitive adhesive 20 are not destroyed by heating at about 1 MPa but are destroyed by heating at 90 ° C. .

  First, when the entire pressure-sensitive adhesive is pressurized at 1 MPa at room temperature (25 ° C.), the release agent 13 oozes out from the microcapsule 12, and the release agent 13 comes into contact with the base adhesive 11 so that the adhesive strength is reduced. Peeling occurs at the interface with the adherend 31.

Next, when the entire pressure-sensitive adhesive is heated to 90 ° C. in a state where no pressure is applied, the release agent 23 oozes out from the microcapsule 22, and the release agent 23 comes into contact with the base pressure-sensitive adhesive 21, thereby reducing the adhesive force. Then, peeling occurs at the interface with the adherend 32.
Thus, by selecting the means of pressurization or heating, it is possible to arbitrarily select the interface where the adhesive peels off from the part, which is suitable for recycling the part.

See Figure 4
FIG. 4 is a conceptual configuration diagram of a pressure-sensitive adhesive sheet having a base material, in which a pressure-sensitive peelable pressure-sensitive adhesive 10 is provided on one side of a base material 41 serving as a support base, and a heat-peelable pressure-sensitive adhesive 20 is provided on the other side. And release sheets 42 and 43 are provided on the surfaces thereof.

As the base material 41 in this case, a plastic film or sheet is generally used. For example, paper, cloth, nonwoven fabric, metal foil, or a suitable thin leaf body such as a plastic laminate or a laminate of plastics. Can be used.
Furthermore, the base material 41 may have a conductor layer and a magnetic layer, or / and contain conductive powder and magnetic powder and can be induction-heated via high frequency.

Moreover, although the thickness of the base material 41 is 500 micrometers or less, especially 5-250 micrometers is common, it is not limited to this.
The release sheets 42 and 43 are typically materials used as a sealing material surface material, such as polyester film, polypropylene film, polystyrene film, synthetic paper (YUPO), vinyl chloride film, or polyimide for film substrates. Use a film or the like.

See Figure 5
FIG. 5 is a conceptual configuration diagram of a pressure-sensitive adhesive sheet having no base material. After the pressure-sensitive release pressure-sensitive adhesive 10 is provided on the release sheet 44 and the heat-release type pressure-sensitive adhesive 20 is provided on the release sheet 45, pressure-sensitive release is performed. For example, the mold pressure-sensitive adhesive 10 and the heat-peelable pressure-sensitive adhesive 20 are bonded to each other so as to face each other.
As the release sheets 44 and 45, the material of the release sheets 42 and 43 described above is used.

Next, specific materials for forming the above-mentioned adhesive layer will be described.
First, as the shell material of the microcapsule, for example, protein and polysaccharide such as gelatin-gum arabic, PVA (polyvinyl alcohol), polyurethane, thermoplastic resin (vinylidene chloride, acrylonitrile, styrene, alkyl acrylate) And methamine-formaldehyde resins, isocyanate resins, and the like are preferred.

At this time, in terms of material design, it is necessary to make the heat resistance of the pressure-breaking microcapsules relatively high and to make the pressure resistance of the heat-breaking microcapsules relatively high. This is because the breakage of the pressure breakable microcapsule is mainly adjusted by pressurization, and the breakage of the heat breakable microcapsule is mainly adjusted by heating.
For this purpose, the melting point of the shell material is adjusted in the heat-breaking microcapsules, and the thickness of the shell material is mainly adjusted in the pressure-breaking microcapsules.

As the melting point of the heat-breakable microcapsules, the heat peelability can be exhibited at a predetermined temperature by designing the material between the melting points of 50 to 200 ° C.
The definition of “melting point” is as described above.

Moreover, in order to design the microcapsule to be broken by pressurization, the capsule shell material, the capsule particle size, the capsule film thickness, and the like can be appropriately adjusted to cause pressure breakage between 1 MPa and 5 MPa.
In this case, the breaking pressure increases as the capsule film thickness increases, and the breaking pressure decreases as the capsule particle size increases.

  In addition, the melting points of the microcapsule shell material enclosing the release agent need not all be the same. For the purpose of adjusting the adhesive strength in stages, the amount of destruction of the microcapsules by having a plurality of melting points. You may adjust.

  Similarly, the pressure resistance of the microcapsules encapsulating the release agent does not have to be the same. For the purpose of adjusting the adhesive force step by step, the amount by which the microcapsules are destroyed by having multiple pressure resistances May be adjusted.

As the microencapsulation method, conventionally known coacervation method, interfacial polymerization method, in-situ polymerization method and the like are appropriately selected and used.
When a synthetic resin such as a melamine / formaldehyde resin or an isocyanate resin is used as a wall film agent, it has excellent water resistance and solvent resistance.
These microcapsules may contain auxiliary agents such as antioxidants and ultraviolet absorbers as necessary.

  Further, the average particle size of the microcapsules is preferably in the range of 1 to 50 μm, preferably 1 to 50 μm, and the content of the release agent is proportional to the cube of the microcapsule particle size. If the particle size is less than 1 μm, the release agent becomes too small and the releasability is not sufficient, and if the average particle size exceeds 50 μm, the particle size is almost equal to the layer thickness of the adhesive, so there is no adhesive component The microcapsule occupies most of the adhesive layer, and sufficient adhesiveness cannot be obtained.

  Examples of the release agent included in the microcapsule include higher fatty acids, higher fatty acid derivatives, organopolysiloxane compounds, waxes, higher alcohols, mineral oils, animal oils, vegetable oils, silicone oils, and the like. It is not limited to these, and two or more release agents can be used in combination.

These release agents are blended in an amount of 3 to 90% by dry weight with respect to the oil solution in microencapsulation.
Furthermore, in order to be able to select an arbitrary release interface conveniently, it is desirable that the amount of the release agent that exudes the pressure-sensitive release adhesive layer and the heat release adhesive layer is equal.

  Moreover, as an addition amount with respect to the adhesive of a mold release agent, it is desirable that a mold release agent is 1-20 wt% with respect to a base adhesive, and when it is less than 1 wt% by weight ratio, there is no mold release effect, When the weight ratio exceeds 20 wt%, the adhesive component decreases and sufficient adhesiveness cannot be obtained.

Moreover, you may contain a thermally expansible microparticle sphere in an adhesion layer, and can exhibit peelability further in the case of a heating.
This is because the heat-expandable microparticle swells by heating and expands the adhesive layer, so that the release agent can easily penetrate into the entire adhesive layer.
At this time, the heat-expandable microparticle spheres may be encapsulated alone in the microcapsule or may further promote the peeling effect when encapsulated in the microcapsule together with the release agent.

  As the heat-expandable microparticle sphere, for example, a material that is easily gasified such as isobutane, propane, or pentane and that has a heat-expandability is encapsulated in a shell-forming material by a coacervation method or an interfacial polymerization method is used. be able to.

At that time, when the foaming temperature of the thermally expandable microparticle sphere is in the range of 50 to 200 ° C., the heat peelability can be further exhibited.
If the foaming temperature of the heat-expandable microparticle sphere is less than 50 ° C., the heat-expandable microparticle sphere may be ruptured and the adhesiveness may be lowered even during normal times. When the temperature exceeds 200 ° C., heating at 200 ° C. or higher is required for peeling, and the adherend is thermally deteriorated.
The “foaming temperature” is a temperature at which the thermally expandable microparticle spheres start to expand.

  At this time, it is desirable that the heat-expandable microparticle sphere is 1 to 20 wt% by weight with respect to the base adhesive, and if the weight ratio is less than 1 wt%, there is no mold release effect, while If it exceeds 20 wt%, the adhesive component is reduced and sufficient adhesion cannot be obtained.

The average particle diameter of the thermally expandable microparticle spheres is preferably in the range of 1 to 50 μm, desirably 1 to 50 μm, and if the average particle diameter is less than 1 μm, the adhesive layer can be expanded even if thermally expanded. Therefore, sufficient releasability cannot be obtained.
On the other hand, when the average particle diameter of the thermally expandable microparticle spheres exceeds 50 μm, the particle diameter becomes almost equal to the layer thickness of the pressure-sensitive adhesive. Therefore, the thermally expandable microparticle spheres having no adhesive component occupy most of the adhesive layer. Sufficient adhesion cannot be obtained.

  When the thermally expandable microparticle sphere is included, the base adhesive constituting the heat-peelable adhesive layer is preferably a material that allows foaming and / or expansion of the thermally expandable microparticle sphere when heated. The thermally expandable microparticle spheres are not ruptured by foaming until the volume expansion rate is 5 times or more, particularly 10 times.

In this case, the shell of the thermally expandable microparticle sphere is made of, for example, a thermally fusible material such as vinylidene chloride / acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, or the like. Use destructive material.
Incidentally, as such thermally expandable microparticle spheres, for example, microspheres (trade name, manufactured by Matsumoto Yushi Co., Ltd.) are commercially available.

In addition, examples of the base adhesive constituting each adhesive include rubber-based, acrylic-based, vinyl alkyl ether-based, silicone-based, polyester-based, polyamide-based, urethane-based, styrene / diene block copolymer system, epoxy-based, etc. Known pressure-sensitive adhesives such as those obtained by blending a heat-melting resin having a melting point of about 200 ° C. or less to improve creep characteristics (for example, Japanese Patent Laid-Open Nos. 56-061468, 61-174857, and Sho-sho) 63-017981 and Japanese Examined Patent Publication No. 56-13040) can be used.
The pressure-sensitive adhesive may be a blend of appropriate additives such as a crosslinking agent, a tackifier, a plasticizer, a filler, and an anti-aging agent.

  Generally, rubber adhesives based on natural rubber and various synthetic rubbers, methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group, heptyl group, cyclohexyl group, 2-ethylhexyl group, isooctyl group Group, isodecyl group, dodecyl group, lauryl group, tridecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group and the like, such as acrylic acid or methacrylic acid, etc. An acrylic pressure-sensitive adhesive, an epoxy pressure-sensitive adhesive, or the like based on an acrylic polymer using one or more acrylic acid-based alkyl esters composed of an ester is used.

The base pressure-sensitive adhesive constituting the heat-peelable pressure-sensitive adhesive layer has a dynamic elastic modulus of from 50,000 to 10,000,000 at room temperature to 150 ° C. in order to achieve a large adhesive force before heating and a large decrease in adhesive strength by heating. A dyn / cm ² polymer is used as a base polymer.

  The adhesive layer can be formed, for example, by mixing microcapsules or thermally expandable microparticle spheres with a solvent as required in the adhesive, and mixing the mixture on the substrate via a rubbery organic elastic layer as necessary. It can be carried out by an appropriate method such as a method of applying to the substrate or a method of transferring the adhesive layer formed on the separator in accordance with the method onto the substrate.

  The rubbery organic elastic layer placed between the base material and the adhesive layer as needed, when the heat-peelable adhesive sheet is adhered to the adherend, the surface follows the surface shape of the adherend well. To provide a large bonding area, and to restrain foaming and / or expansion in the surface direction of the heat-peelable pressure-sensitive adhesive sheet when the pressure-sensitive adhesive layer is heated and foamed and / or expanded to peel from the adherend. Thus, the pressure-sensitive adhesive layer serves to promote the three-dimensional deformation of the mountain-shaped convex mountain structure, undulation structure, or corrugated structure.

The rubber-like organic elastic layer may be formed by an appropriate method, for example, a method of applying the above-described forming material solution onto the substrate, or a method of bonding a film or the like made of the forming material to the substrate.
In the present invention, the rubber-like organic elastic layer may be formed of an adhesive substance mainly composed of natural rubber, synthetic rubber, or synthetic resin having rubber elasticity, or a foam film mainly composed of such a component. It may be formed by.

  In addition, the pressure-sensitive peelable adhesive and the base pressure-sensitive adhesive used for the heat-peelable pressure-sensitive adhesive are not necessarily the same, but considering the peeling effect of the same component release agent, the pressure-sensitive adhesive is also the same component. Some are desirable.

  With the above-described configuration, the heat-peelable pressure-sensitive adhesive of the present invention can arbitrarily select the peeling interface between the pressure-sensitive adhesive sheet and the adherend part, and has a 180 ° peeling adhesive strength (peeling speed 300 mm / min.) To a stainless steel plate at 25 ° C. Is 800 g / 25 mm or more, and by pressing or heating to the peeling design temperature, the adhesive strength can be reduced to 80 g / 25 mm or less.

  A pressure-sensitive adhesive layer containing a microcapsule that encapsulates a release agent, the microcapsule being destroyed only by heating, and a microcapsule that is destroyed only by applying pressure as well as heating. By constituting it into two layers with the containing layer, it is possible to arbitrarily select the peeling interface by heating or heating + pressurization of the pressure-sensitive adhesive.

  For example, the pressure breaking type microcapsule has a lower breaking pressure as the temperature becomes higher. For example, when the breaking set pressure is 2 MPa, a pressure breaking type microcapsule having a breaking set pressure at room temperature of 2.5 MPa is used. Thus, the fracture condition of the pressure fracture type microcapsule may be 2 MPa + heating.

In this case, even if a pressure of 2 MPa is applied unintentionally, if no heat is applied, the pressure-sensitive peelable pressure-sensitive adhesive layer does not peel.
Note that the shell material of the pressure fracture type microcapsule is selected so that the heating condition at this time is lower than the fracture set temperature of the heat fracture type microcapsule.

  In addition, since the destruction temperature of the heat destruction type microcapsule decreases as the pressure increases, for example, when the destruction setting temperature is set to 90 ° C., the destruction destruction temperature is 100 ° C. in the state where the pressure is not applied. Using capsules, the breakage condition of the heat breakable microcapsules may be 90 ° C. + pressure.

In this case, even if heat of 90 ° C. is applied unintentionally, if no pressure is applied, the heat-peeling-type adhesive layer does not peel.
It should be noted that the shell thickness and particle size of the heat destructible microcapsules are designed so that the pressurizing condition at this time is lower than the destructive set pressure of the thickness destructive microcapsules.

Based on the above, the method for manufacturing the pressure-sensitive adhesive sheet of Example 1 of the present invention will be described.
First, 80 parts of fluorine-modified silicone oil FS 1265 1000CS (manufactured by Shiwa Sangyo Co., Ltd.), 180 parts of a 4% aqueous solution of ethylene-maleic anhydride copolymer prepared with a pH of 6.0, After emulsification using a homogenizer, this emulsion is heated to 40 ° C.

  On the other hand, a prepolymer aqueous solution obtained by adding 20 parts of melamine to 40 parts of a 40% formaldehyde aqueous solution and reacting at 40 ° C. for 15 minutes is dropped into the above emulsion and further stirred with 0.1 N. Of hydrochloric acid was added dropwise to adjust the pH to 5.3, and then the system was heated to 80 ° C. and stirred for 1 hour. Subsequently, 0.2N hydrochloric acid was added dropwise to lower the pH to 3.5. After stirring for a period of time, the mixture was cooled to obtain a pressure fracture type microcapsule dispersion having an average particle size of 10 μm.

The melting point of the shell material of this pressure fracture type microcapsule was 120 ° C. as a result of the above-mentioned measurement by DSC.
Further, the microcapsules were not broken by pressurization of less than 1 MPa, and the microcapsules were broken only after pressurization of 1 MPa or more.

  In the same manner as the pressure-breaking microcapsules, the degree of polymerization of the ethylene-maleic anhydride copolymer and the reaction temperature are adjusted, and the melting point of the shell material containing the release agent is 90 ° C., even at a pressure of 5 MPa. Heat-breakable microcapsules that are not destroyed are produced.

Next, the pressure breakable microcapsule dispersion was filter-pressed and air-dried to obtain a powder pressure breakable microcapsule.
Similarly, powder heat breakable microcapsules were produced from a dispersion of heat breakable microcapsules.

Next, 30 parts by weight of powder pressure breakable microcapsules are mixed with 100 parts by weight of an epoxy-based pressure-sensitive adhesive to produce a pressure-sensitive peelable pressure-sensitive adhesive, which is applied to one side of a substrate made of a polyester film having a thickness of 100 μm. A pressure-sensitive peelable adhesive layer having a thickness of 50 μm was formed.
The weight ratio of the release agent in this pressure-sensitive peelable pressure-sensitive adhesive was 10 wt%.

Next, in the same manner, a heat-peelable pressure-sensitive adhesive was prepared from 30 parts by weight of the powder heat-breakable microcapsule, and the thickness of the polyester film serving as the base material on the surface where the pressure-sensitive peelable pressure-sensitive adhesive layer was not formed. A pressure-sensitive adhesive sheet was prepared by forming a 50 μm heat-peelable pressure-sensitive adhesive layer.
In addition, the weight ratio of the release agent in this heat-peelable pressure-sensitive adhesive was 10 wt%, and the same amount as the release agent in the pressure-sensitive peelable pressure-sensitive adhesive.

The adhesive force and the peeled surface of the adhesive were evaluated for Example 1 of the present invention thus produced.
First, when measuring the adhesive force, a stainless steel plate (SUS304, BA finished surface) was used as an adherend, and a 180 ° peel test was performed at a peel rate of 300 mm / min at room temperature (25 ° C.) according to JISZ0237. The adhesive strength at room temperature was obtained.
Pulling in the direction perpendicular to the bonding surface is called 90 ° peeling, and pulling in the opposite direction so that the bonding surface is turned over is called 180 ° peeling.

  Incidentally, in the case of the adhesive sheet of Example 1, the adhesive force immediately after the adhesion was 1200 gf / 25 mm, the adhesive force after 30 days after the adhesion was 1200 gf / 25 mm, and no decrease in the adhesive strength was observed.

  Next, the oven temperature is set to 90 ° C., which is the respective peel design value, and left for 10 minutes under this heat treatment condition, and then the 180 ° peel test at room temperature described above is performed to measure the adhesive strength after heat treatment. As a result, the adhesive strength was 60 gf / 25 mm, which was greatly reduced.

  In addition, the test piece of the adherend is pressed from above and below with a vise, and the pressure applied at this time is adjusted to 1 MPa with a torque meter and left under this pressure treatment condition for 10 minutes. When the adhesive strength after pressure treatment was measured by performing a 180 ° peeling test at 70 ° C., the adhesive strength was 70 gf / 25 mm, which was significantly reduced.

  Next, as an evaluation of the peeled surface of the adhesive, after using a glass plate FL2.0 (Nippon Sheet Glass Co., Ltd. product model number) as the adherend, and bonding the two glass plates with an adhesive member, The above-described pressure treatment and heat treatment were pressurized or heated under the same conditions, and after peeling at 180 ° at room temperature, the peeling interface was examined.

At this time, in the pressure treatment of 1 MPa, the pressure-sensitive peelable pressure-sensitive adhesive layer side peeled as designed, and no peeling was observed on the heat-peelable pressure-sensitive adhesive layer side.
Moreover, even in the heat treatment at 90 ° C., the heat-peelable pressure-sensitive adhesive layer side peeled as designed, and no peeling was observed on the pressure-sensitive peelable pressure-sensitive adhesive layer side.

  As described above, it was found that the pressure-sensitive adhesive sheet of Example 1 exhibited a sufficient adhesive force at room temperature, and the adhesive force was lowered according to heating or pressurization up to the release design value, so that the release interface could be selected. .

[Comparative Example 1]
A pressure-sensitive adhesive sheet was produced in the same configuration as in Example 1 except that the melting points of both microcapsule shell materials were 40 ° C.
When the 180 ° peel test and the peeled surface observation described above were performed on the pressure-sensitive adhesive sheet of Comparative Example 1, the adhesive strength immediately after the sticking was 1200 gf / 25 mm, but the adhesive strength after 30 days after sticking was 500 gf / It was 25 mm, and a significant decrease in adhesive strength was observed.

Further, the adhesive strength after the heat treatment was reduced to 20 gf / 25 mm, and the adhesive strength after the pressure treatment was also reduced to 80 gf / 25 mm.
Moreover, in the peeling surface observation, peeling was observed on both sides in both cases of pressurization and heating.

[Comparative Example 2]
A pressure-sensitive adhesive sheet was produced in the same configuration as in Example 1 except that the melting point of both microcapsule shells was 200 ° C.
When the above-mentioned 180 ° peel test and peel surface observation were performed on the pressure-sensitive adhesive sheet of Comparative Example 2, the adhesive strength immediately after the sticking was 1200 gf / 25 mm, and the adhesive strength after 30 days after sticking was 1200 gf / 25 mm. And no decrease in adhesive strength was observed.

Further, the adhesive strength after the heat treatment hardly decreased to 1100 gf / 25 mm, and the adhesive strength after the pressure treatment did not substantially decrease to 1100 gf / 25 mm.
Further, in the peeled surface observation, no peeling was observed on both sides in either case of pressing and heating.
This is presumed that when the melting point of the shell material is as high as 200 ° C., the pressure resistance of the pressure-sensitive peelable adhesive layer is increased, while the heat peelable adhesive having a melting point of 200 ° C. is naturally at 90 ° C. This is because peeling does not occur.

[Comparative Example 3]
When producing the pressure fracture type microcapsule, the material composition and manufacturing conditions are adjusted, and the fracture pressure is set to 10 MPa or more by appropriately controlling the particle size and the film thickness of the shell material. A pressure-sensitive adhesive sheet having the same configuration as that of No. 1 was prepared.
When the 180 ° peel test and the peeled surface observation described above were performed on the pressure-sensitive adhesive sheet of Comparative Example 3, the adhesive strength immediately after sticking was 1200 gf / 25 mm, and the adhesive strength after 30 days after sticking was 1200 gf / 25 mm. And no decrease in adhesive strength was observed.

Further, the adhesive strength after the heat treatment was 60 gf / 25 mm, which was the same decrease as in Example 1. However, the adhesive strength after the pressure treatment was not reduced to 1200 gf / 25 mm.
Further, in the observation of the peeled surface, in the heat treatment, as in Example 1, the side of the heat peelable adhesive layer peeled off, and no peeling was observed on the pressure sensitive peelable adhesive layer side. Since the fracture pressure of both shell materials was 10 MPa or more, no peeling was observed in either Kaga at a pressure of 1 MPa.

[Comparative Example 4]
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the melting point of the shell material was adjusted to 120 ° C. by adjusting the polymerization degree and reaction temperature when preparing the heat-breakable microcapsules.
When the 180 ° peel test and the peeled surface observation described above were performed on the pressure-sensitive adhesive sheet of Comparative Example 4, the adhesion immediately after adhesion was 1200 gf / 25 mm, and the adhesion after 30 days after adhesion was 1200 gf / 25 mm. And no decrease in adhesive strength was observed.

In addition, the adhesive strength after the heat treatment was found to be 1200 gf / 25 mm and no decrease was observed, and the adhesive strength after the press treatment was 70 gf / 25 mm, a decrease similar to that in Example 1.
Moreover, in the peeling surface observation, in the pressure treatment, as in Example 1, the pressure-sensitive peelable pressure-sensitive adhesive layer side peeled off, and no peeling was observed on the heat-peelable pressure-sensitive adhesive layer side. The heat-peelable adhesive layer having a melting point of 120 ° C. naturally did not peel at 90 ° C.

  Next, Example 2 will be described. The same as Example 1 except that 10 wt% of thermally expandable particles having an average particle diameter of 10 μm and a foaming temperature of 90 ° C. are contained in the base adhesive in a weight ratio. A pressure-sensitive adhesive sheet is produced in the process, and has a laminated structure of (pressure-sensitive + heating) / (heating).

  When the 180 ° peel test and the peeled surface observation described above were performed on the pressure-sensitive adhesive sheet of Example 2, the adhesive strength immediately after the sticking was 1000 gf / 25 mm, and the adhesive strength after 30 days after sticking was 1000 gf / 25 mm. No decrease in adhesive strength was observed.

In addition, the adhesive strength after the heat treatment was significantly reduced to 40 gf / 25 mm, and the adhesive strength after the pressure treatment was 60 gf / 25 mm, which was lower than that of Example 1.
Moreover, in the peeled surface observation, the pressure-sensitive peelable pressure-sensitive adhesive layer side peels off in the pressure treatment, and peeling is observed on the heat-peelable pressure-sensitive adhesive layer side. Similarly, the heat-peelable pressure-sensitive adhesive layer side peeled off, and no peeling was observed on the pressure-sensitive peelable pressure-sensitive adhesive layer side.

  In Example 2, since the heat-expandable adhesive layer contains thermally expandable particles that foam at 90 ° C., the heat-expandable particles foam by the heat treatment at 90 ° C. This is presumed to have been promoted.

[Comparative Example 5]
A pressure-sensitive adhesive sheet was produced in the same configuration as in Example 2 except that the expansion temperature of the thermally expandable particles to be contained was 70 ° C.
When the 180 ° peel test and the peeled surface observation described above were performed on the pressure-sensitive adhesive sheet of Comparative Example 5, the adhesive strength immediately after the sticking was 1000 gf / 25 mm, and the adhesive strength after 30 days from the sticking was 700 gf / 25 mm. A decrease in adhesive strength was observed.

In addition, the adhesive strength after the heat treatment was reduced to 20 gf / 25 mm, and the adhesive strength after the pressure treatment was also reduced to 80 gf / 25 mm.
Moreover, in the peeling surface observation, peeling was observed on both sides in both cases of pressurization and heating.

Next, Example 3 will be described, except that heat-expandable particles having an average particle diameter of 10 μm and a foaming temperature of 90 ° C. are contained in the heat-breakable microcapsules, and the microcapsule particle diameter is 50 μm. A pressure-sensitive adhesive sheet was produced in the same configuration as in Example 1.
In this case, the thermally expandable particles have a content of 10 wt% with respect to the base adhesive and 0.5 wt% with respect to the release agent.

  When the 180 ° peel test and the peeled surface observation described above were performed on the pressure-sensitive adhesive sheet of Example 2, the adhesive strength immediately after the sticking was 1100 gf / 25 mm, and the adhesive strength after 30 days from the sticking was 1100 gf / 25 mm. And no decrease in adhesive strength was observed.

Further, the adhesive strength after the heat treatment was 50 gf / 25 mm, which was the same as that of Example 1, and the adhesive strength after the pressure treatment was 80 gf / 25 mm, which was the same as that of Example 1.
Moreover, in the peeled surface observation, the pressure-sensitive peelable pressure-sensitive adhesive layer side peels off in the pressure treatment, and peeling is observed on the heat-peelable pressure-sensitive adhesive layer side. Similarly, the heat-peelable pressure-sensitive adhesive layer side peeled off, and no peeling was observed on the pressure-sensitive peelable pressure-sensitive adhesive layer side.

See FIG.
FIG. 6 summarizes the above results, and the pressure-sensitive adhesive sheets of Examples 1 to 3 of the present invention all show a sufficient adhesive force at room temperature, and respond to heating or pressurization up to the peel design value. As a result, the adhesive strength was reduced, and it was found that the peeling interface can be selected.

Here, the detailed features of the present invention will be described again with reference to FIG.
Again see Figure 1
(Additional remark 1) While enclosing the mold release agent 3, it encloses the pressure-sensitive peeling type adhesive 1 and the mold release agent 6 including at least the pressure destructive microcapsule 2 to be pressure-destructed, and is destroyed by heating. The heat-breakable microcapsule 5 includes at least a heat-peelable pressure-sensitive adhesive 4 and the pressure-breakable microcapsule 2 does not break at the breakage setting temperature of the heat-breakable microcapsule 5, and The pressure-sensitive adhesive is characterized in that the heat-breakable microcapsule 5 does not break at the pressure set for the pressure-breakable microcapsule 2.
(Additional remark 2) The said pressure fracture-type microcapsule 2 is pressure fractured by 1 MPa-5 MPa, The said heat fracture-type microcapsule 5 is destroyed by the heating of 50-200 degreeC, The additional statement 1 characterized by the above-mentioned. Adhesive.
(Supplementary note 3) Supplementary note 1 or 3, wherein the heat destruction type microcapsule 5 is destroyed by applying a failure setting temperature under a pressure application condition that is equal to or lower than a pressure setting value of the pressure destruction type microcapsule 2. 2. The pressure-sensitive adhesive according to 2.
(Additional remark 4) The said pressure destruction-type microcapsule 2 destroys by applying a destruction setting pressure on the heating conditions by the temperature below the destruction setting temperature of the said heat destruction type microcapsule 5. Or the adhesive of 2.
(Supplementary Note 5) The total amount of the release agent 3 that exudes from the pressure breakable microcapsule 2 in the pressure sensitive peelable adhesive 1 and the exudate from the heat destructible microcapsule 5 in the heat peelable adhesive 4. The pressure-sensitive adhesive according to any one of supplementary notes 1 to 4, wherein the total amount of the release agent 6 is the same amount.
(Additional remark 6) The release agent 3 included in the said pressure destruction type | mold microcapsule 2 and the release agent 6 included in the said heat destruction type | mold microcapsule 5 are the same components. 5. The pressure-sensitive adhesive according to any one of 5 above.
(Supplementary note 7) The pressure-sensitive adhesive according to any one of supplementary notes 1 to 6, wherein the pressure-sensitive peelable pressure-sensitive adhesive 1 includes a plurality of types of pressure-breaking microcapsules 2 having different breaking pressures. Agent.
(Appendix 8) The heat peelable pressure-sensitive adhesive 4 includes a plurality of types of heat-breakable microcapsules 5 made of shell materials having different melting points, according to any one of appendices 1 to 7, Adhesive.
(Appendix 9) The pressure-sensitive release adhesive 1 and the heat-release adhesive 4 contain 1 to 20 wt% of release agents 3 and 6 by weight with respect to the base adhesive. The pressure-sensitive adhesive according to any one of supplementary notes 1 to 8.
(Supplementary note 10) The pressure-sensitive adhesive according to any one of supplementary notes 1 to 9, wherein the heat breakable microcapsule 5 and the pressure breakable microcapsule 2 have an average particle size of 1 to 50 µm.
(Appendix 11) The pressure-sensitive adhesive according to any one of appendices 1 to 10, wherein the heat breakable microcapsule 5 contains thermally expandable microparticle spheres.
(Additional remark 12) The foaming temperature of the said thermally expansible microparticle sphere is 50-200 degreeC, The adhesive of Additional remark 11 characterized by the above-mentioned.
(Supplementary note 13) Any one of Supplementary notes 1 to 12, wherein the base pressure-sensitive adhesive constituting the pressure-sensitive peelable pressure-sensitive adhesive 1 and the base pressure-sensitive adhesive constituting the heat-peelable pressure-sensitive adhesive 4 are the same component. The pressure-sensitive adhesive according to 1.
(Additional remark 14) It is an adhesive sheet using the adhesive of any one of Additional remarks 1 thru | or 13, Comprising: The pressure sensitive peelable adhesive layer which consists of the said pressure sensitive peelable adhesive 1, and the said heat peelable adhesive 4 A pressure-sensitive adhesive sheet, which is in direct contact with a heat-peelable pressure-sensitive adhesive layer.
(Additional remark 15) It is an adhesive sheet using the adhesive of any one of Additional remarks 1 thru | or 13, Comprising: The pressure sensitive peelable adhesive layer which consists of the said pressure sensitive peelable adhesive 1, and the said heat peelable adhesive 4 A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive sheet is provided so as to face the heat-peelable pressure-sensitive adhesive layer.
(Appendix 16) In the appendix 14 or 15, wherein the pressure-sensitive peelable adhesive layer and the heat peelable adhesive layer have at least one of hue, brightness, or saturation different from each other The adhesive sheet as described.
(Supplementary note 17) An electronic tag, wherein the pressure-sensitive adhesive according to any one of supplementary notes 1 to 13 or the pressure-sensitive adhesive sheet according to any one of supplementary notes 14 to 16 is adhered.

  As an application example of the present invention, a double-sided pressure-sensitive adhesive sheet is typical, but a two-layered pressure-sensitive adhesive may be attached to a component such as an IC tag. It becomes the agent itself.

It is explanatory drawing of the fundamental structure of this invention. It is a basic lineblock diagram of the adhesive of the present invention. It is explanatory drawing of the peeling surface selection principle in embodiment of this invention. It is a notional block diagram of the adhesive sheet which has a base material. It is a notional block diagram of an adhesive sheet without a substrate. It is explanatory drawing of the adhesive force and peeling state of the adhesive sheet of Example 1 thru | or Example 3 and Comparative Example 1 thru | or Comparative Example 5 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure-sensitive peeling type adhesive 2 Pressure destruction type microcapsule 3 Release agent 4 Heating release type adhesive 5 Heat breaking type microcapsule 6 Release agent 7 Adhering body 8 Adhering body 10 Pressure sensitive peeling type adhesive 11 Base adhesive 12 Microcapsule 13 Release agent 20 Heat release adhesive 21 Base adhesive 22 Microcapsule 23 Release agent 31, 32 Substrate 41 Substrate 42-45 Release sheet

Claims (5)

A pressure-sensitive peelable pressure-sensitive adhesive containing at least a pressure-breaking microcapsule that is pressure-destructed to be pressure-destructed and encapsulating a release agent, and a heat-destruction that encapsulates the release agent and is destroyed by heating The pressure breakable microcapsule does not break at the set breaking temperature of the heat breakable microcapsule, and the heat breakable microcapsule A pressure-sensitive adhesive that does not break at the pressure at which the pressure breakage type microcapsule is broken. The total amount of release agent that exudes from the pressure-breaking microcapsules in the pressure-sensitive release adhesive and the total amount of release agent that exudes from the heat-breakable microcapsules in the heat-peelable adhesive are the same amount. The pressure-sensitive adhesive according to claim 1, wherein 3. The pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive peelable pressure-sensitive adhesive and the heat-peelable pressure-sensitive adhesive contain 1 to 20 wt% of a release agent in a weight ratio with respect to the base pressure-sensitive adhesive. Agent. The pressure-sensitive adhesive according to any one of claims 1 to 3, wherein the heat-breakable microcapsule contains thermally expandable microparticle spheres. A pressure-sensitive adhesive sheet using the pressure-sensitive adhesive according to claim 1, wherein the pressure-sensitive peelable pressure-sensitive adhesive layer is made of the pressure-sensitive peelable pressure-sensitive adhesive and the heat-peelable pressure-sensitive adhesive is made of the heat-peelable pressure-sensitive adhesive. A pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive sheet is provided so as to face the mold adhesive layer with a base material interposed therebetween.

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