JP2021161150A - Adhesive sheet - Google Patents

Abstract

To provide an adhesive sheet that can be easily removed from an adherend by application of high-frequency waves.SOLUTION: An adhesive sheet contains thermally-expandable particles and a dielectric heating filler and has a thermally-expandable layer (A) containing at least the thermally-expandable particles. The dielectric heating filler is at least one selected from the group consisting of metal oxide and metalloid carbide.SELECTED DRAWING: None

Description

The present invention relates to an adhesive sheet. More specifically, the present invention relates to an adhesive sheet that can be easily peeled off from an adherend by applying a high frequency.

Adhesive sheets may be used not only for semi-permanently fixing members, but also for temporarily fixing target members when processing or inspecting building materials, interior materials, electronic parts, etc. ..
As an example, in the manufacturing process of a semiconductor device, an adhesive sheet is used as a temporary fixing sheet when processing a semiconductor wafer or using a material for an electronic device such as a semiconductor chip. In this way, when the adhesive sheet is attached to an adherend such as a material for an electronic device and then peeled off after use, the adherend is not subjected to an excessive load. It is desirable to be able to do it.
Similarly, the adhesive sheet may be used as a protective material such as a protective film, wallpaper, various labels, or the like. If the adhesive sheet attached to the adherend can be peeled off from the adherend without applying a load, problems such as contamination, deformation, and breakage of the adherend caused by the adhesive sheet will occur. Reduction and prevention can be expected.
As described above, when the adhesive sheet is temporarily attached to the adherend and used, the adhesive sheet is required to exhibit sufficient adhesive force at the time of attachment and to have excellent peelability at the time of peeling. ..

For example, Patent Document 1 discloses a heat-release type pressure-sensitive adhesive sheet for temporarily fixing an electronic component when a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres is provided on at least one surface of a base material. ing. Since the heat-release type adhesive sheet can secure a contact area with an adherend when cutting an electronic component, it can exhibit adhesiveness capable of preventing adhesive defects such as chip skipping, and on the other hand, it is heated after use. There is a description that if the heat-expandable microspheres are expanded, the contact area with the adherend can be reduced so that the microspheres can be easily peeled off.

Japanese Patent No. 3594853

By the way, in recent years, when an adhesive sheet as disclosed in Patent Document 1 is used in the manufacturing process of various products or used for various other purposes, the adhesive sheet is adherent in order to exhibit the easy peeling property. There is a restriction that the sheet must be placed in a heatable environment. Further, since the adherend to which the adhesive sheet is attached is also exposed to a high temperature environment, there is a demand to reduce the heat history applied to the adherend as much as possible. From this point of view, it is required to develop a new adhesive sheet that can reduce the peeling force when peeling from the adherend by using a new method.
From this point of view, it is an object of the present invention to provide an adhesive sheet that can be easily peeled off from an adherend by applying a high frequency.

The present inventors have found that a pressure-sensitive adhesive sheet containing a heat-expandable particle and a specific dielectric heat-generating filler and having a heat-expandable layer (A) containing at least the heat-expandable particles can solve the above-mentioned problems. The present invention has been completed.
That is, the present invention provides the following [1] to [11].
[1] An adhesive sheet containing a heat-expandable particle and a dielectric heating filler, and having a heat-expandable layer (A) containing at least the heat-expandable particles.
An adhesive sheet in which the dielectric heating filler is at least one selected from the group consisting of metal oxides and semimetal carbonized metals.
[2] The pressure-sensitive adhesive sheet according to the above [1], wherein the dielectric heating filler is at least one selected from the group consisting of zinc oxide, titanium oxide, barium titanate, and silicon carbide.
[3] The pressure-sensitive adhesive sheet according to the above [1] or [2], wherein the layer (A) contains the dielectric heating filler.
[4] The pressure-sensitive adhesive sheet according to [3], wherein the content of the dielectric heating filler in the layer (A) is 1 to 30% by mass.
[5] The pressure-sensitive adhesive sheet according to any one of [1] to [4], wherein the content of the heat-expandable particles in the layer (A) is 1 to 40% by mass.
[6] The pressure-sensitive adhesive sheet according to any one of [1] to [5] above, wherein the layer (A) is a heat-expandable pressure-sensitive adhesive layer (AX).
[7] The above-mentioned [1] to [5], wherein the layer (A) is a heat-expandable base material layer (AY) and has a non-heat-expandable pressure-sensitive adhesive layer (X2) adjacent to the layer (A). The adhesive sheet according to any one.
[8] The adhesive sheet according to any one of the above [1] to [7], which has a support (Y).
[9] The adhesive sheet according to the above [8], wherein the layer (A) and the support (Y) are directly laminated in this order.
[10] The above-mentioned [8] or [9], wherein the layer (A), the support (Y), and the non-thermally expandable pressure-sensitive adhesive layer (X1) not adjacent to the layer (A) are provided in this order. Adhesive sheet.
[11] The pressure-sensitive adhesive sheet according to any one of the above [1] to [10], wherein the thermal expansion start temperature of the heat-expandable particles is 50 to 240 ° C.

According to the present invention, it is possible to provide an adhesive sheet that can be easily peeled off from an adherend by applying a high frequency.

It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet which is one aspect of this invention. It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet which is one aspect of this invention. It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet which is one aspect of this invention. It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet which is one aspect of this invention. It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet which is one aspect of this invention. It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet which is one aspect of this invention. It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet which is one aspect of this invention.

In the present specification, the lower limit value and the upper limit value described stepwise for a preferable numerical range (for example, a range such as content) can be independently combined. For example, from the description "preferably 10 or more, more preferably 30 or more, and preferably 90 or less, more preferably 60 or less", "preferable lower limit value (10)" and "more preferable upper limit value (60)". Can be combined to set a suitable range of "10 or more and 60 or less". Similarly, from the description of "preferably 10 to 90, more preferably 30 to 60", it can be changed to "10 to 60". Unless otherwise specified, when simply describing "10 to 90" as a preferable numerical range, it represents a range of 10 or more and 90 or less.
Further, in the present specification, for example, "(meth) acrylic acid" means both "acrylic acid" and "methacrylic acid", and "(meth) acrylate" means "acrylate" and "methacrylate". Both are indicated, and "(meth) acryloyl group" indicates both "acryloyl group" and "methacrylic acid group", and other similar terms are the same.

Further, in the present specification, the “energy beam” means an electromagnetic wave or a charged particle beam having an energy quantum, and examples thereof include ultraviolet rays, radiation, and electron beams. Ultraviolet rays can be irradiated by using, for example, an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like as an ultraviolet source. The electron beam can be irradiated with an electron beam generated by an electron beam accelerator or the like.
Further, in the present specification, "energy ray polymerizable" means a property of polymerizing by irradiating with energy rays.
Further, in the present specification, the mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, and is specifically measured based on the method described in Examples. It is the value that was set.
Further, in the present specification, the "active ingredient" in the composition refers to a solvent (water or organic solvent contained in the raw material, a diluting solvent, etc.) that is not directly involved in the reaction among the components contained in the composition. It means the excluded component.
Further, in the present specification, "dielectric heat generation" means a characteristic of generating heat by applying a high frequency.
Further, in the present specification, the "high frequency peeling property" means a property that the adhesive strength is lower after the application of the high frequency than before the application of the high frequency, and the adhesive can be easily peeled from the adherend.
Further, in the present specification, "high frequency" means, for example, a frequency of 1 kHz or more, and is preferably in a frequency range of 1 kHz or more and 300 MHz or less.
Further, in the present specification, the thickness of each layer is a value at 23 ° C. before the thermally expandable particles expand before applying a high frequency, and means a value measured by the method described in Examples.

Further, in the present specification, it is determined as follows whether the "layer" is a "non-thermally expandable layer" or a "thermally expandable layer".
When the target layer contains the heat-expandable particles, the layer is heat-treated at the expansion start temperature (t) of the heat-expandable particles for 3 minutes. If the volume change rate calculated from the following formula is less than 5%, the layer is judged to be a "non-thermally expandable layer", and if it is 5% or more, the layer is a "thermally expandable layer". Judge that there is.
Volume change rate (%) = {(volume of the layer after heat treatment-volume of the layer before heat treatment) / volume of the layer before heat treatment} × 100
The layer that does not contain the thermally expandable particles is referred to as a "non-thermally expandable layer".

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet containing heat-expandable particles and a dielectric heating filler and having at least the heat-expandable layer (A) containing the heat-expandable particles. One or more selected from the group consisting of carbide semimetals.
In the pressure-sensitive adhesive sheet of the present invention, the heat-expandable particles are heated by applying a high frequency to the dielectric heat-generating filler to generate heat, and the heat-expandable particles (A) (hereinafter, also referred to as "layer (A)"). .) Expands. As a result, unevenness due to the expanded heat-expandable particles is generated on the adhesive surface to be attached to the target adherend, and the adhesive force of the adhesive surface is reduced, so that the adhesive sheet is removed from the adherend. It can be easily peeled off.
Hereinafter, the pressure-sensitive adhesive sheet of the present invention will be described in more detail, but the aspects of the present invention are not limited thereto.

<Thermal expandable particles>
The thermally expandable particles used in the pressure-sensitive adhesive sheet of the present invention may be particles that expand by heating, and the expansion start temperature (t) is appropriately selected according to the use of the pressure-sensitive adhesive sheet.
For example, if the thermally expandable particles having a low expansion start temperature are used, thermal expansion occurs when the pressure-sensitive adhesive sheet is manufactured, stored, or distributed, or when the usage environment after being attached to an adherend becomes high. Unintended expansion of the sex particles may occur. When such unintended expansion of the heat-expandable particles occurs, the original purpose is that the adherend can be sufficiently held before the high frequency is applied, and the adherend can be easily peeled off by applying the high frequency. It is not possible to play sufficiently, and it leads to unintended separation of the adherend, so it is desirable to suppress it.
From this point of view, in the pressure-sensitive adhesive sheet of one aspect of the present invention, the expansion start temperature (t) of the heat-expandable particles is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, still more preferably 60 ° C. or higher, still more preferably. Is 70 ° C. or higher.
Further, as described above, in the pressure-sensitive adhesive sheet according to one aspect of the present invention, the pressure-sensitive adhesive sheet can be easily peeled off from the adherend by applying a high frequency, so that it is necessary to raise the ambient temperature around the adherend. It is possible to reduce the influence of heat on the adherend.
From the viewpoint of more effectively utilizing such advantages, in the pressure-sensitive adhesive sheet of one aspect of the present invention, the expansion start temperature (t) of the heat-expandable particles is preferably 240 ° C. or lower, more preferably 220 ° C. or lower, still more preferably 220 ° C. or lower. 200 ° C. or lower, still more preferably 180 ° C. or lower, even more preferably 160 ° C. or lower, even more preferably 140 ° C. or lower, even more preferably 120 ° C. or lower, even more preferably 110 ° C. or lower, still more preferably 105 ° C. It is as follows.
In the present specification, the expansion start temperature (t) of the thermally expandable particles means a value measured based on the following method.

(Measuring method of expansion start temperature (t) of thermally expandable particles)
To an aluminum cup having a diameter of 6.0 mm (inner diameter: 5.65 mm) and a depth of 4.8 mm, 0.5 mg of heat-expandable particles to be measured is added, and an aluminum lid (diameter: 5.6 mm, thickness: 0. Prepare a sample on which 1 mm) is placed.
Using a dynamic viscoelasticity measuring device, the height of the sample is measured in a state where a force of 0.01 N is applied to the sample from the upper part of the aluminum lid by a pressurizer. Then, with a force of 0.01 N applied by the pressurizer, it is heated from 20 ° C. to 300 ° C. at a heating rate of 10 ° C./min, the amount of displacement of the pressurizer in the vertical direction is measured, and the displacement in the positive direction is measured. Let the displacement start temperature be the expansion start temperature (t).

The heat-expandable particles are microencapsulated foaming agents composed of an outer shell made of a thermoplastic resin and an contained component contained in the outer shell and vaporized when heated to a predetermined temperature. It is preferable to have.
Examples of the thermoplastic resin constituting the outer shell of the microencapsulating foaming agent include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethylmethacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone.

Examples of the contained components contained in the outer shell of the microencapsulating foaming agent include propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n-heptane, and n. -Low boiling point liquids such as octane, cyclopropane, cyclobutane and petroleum ether can be mentioned.
Among these, the heat-expandable particles are from the viewpoint of reducing the influence of heat on the adherend when peeling by applying a high frequency and suppressing the unintended expansion of the heat-expandable particles due to the temperature rise described above. When the expansion start temperature (t) of is 50 ° C. or higher and 200 ° C. or lower, the inclusion components are preferably propane, isobutane, n-pentane, isopentane, isooctane and cyclopropane.
One of these inclusion components may be used alone, or two or more thereof may be used in combination.
The expansion start temperature (t) of the heat-expandable particles can be adjusted by appropriately selecting the type of the inclusion component.

The average particle size of the heat-expandable particles used in one aspect of the present invention before expansion at 23 ° C. is preferably 3 to 100 μm. When the average particle size is 3 μm or more, it is preferable from the viewpoint that unevenness due to the heat-expandable particles expanded on the surface of the pressure-sensitive adhesive sheet when a high frequency is applied is sufficiently likely to occur, and the average particle size is When it is 100 μm or less, it is preferable because it is possible to prevent deterioration of the adhesiveness of the pressure-sensitive adhesive sheet before applying a high frequency. From this point of view, the average particle size of the thermally expandable particles before expansion at 23 ° C. is more preferably 3 to 70 μm, further preferably 4 to 60 μm, still more preferably 5 to 50 μm, still more preferably 5 to 5. It is 30 μm, more preferably 8 to 20 μm.
The average particle size of the heat-expandable particles before expansion is the volume medium particle size (D ₅₀ ), and a laser diffraction type particle size distribution measuring device (manufactured by Malvern, product name “Mastersizer 3000”) is used. In the particle distribution of the heat-expandable particles before expansion, the cumulative volume frequency calculated from the smaller particle size of the heat-expandable particles before expansion means the particle size corresponding to 50%.

_{The 90% particle size (D 90} ) of the heat-expandable particles before expansion at 23 ° C. used in one aspect of the present invention is preferably 5 to 150 μm. When the 90% particle size (D ₉₀ ) is 5 μm or more, it is preferable from the viewpoint that unevenness due to the heat-expandable particles expanded on the surface of the pressure-sensitive adhesive sheet when a high frequency is applied is sufficiently likely to occur. When the 90% particle size (D ₉₀ ) is 150 μm or less, it is possible to prevent deterioration of the adhesiveness of the pressure-sensitive adhesive sheet before applying a high frequency, which is preferable. From this point of view, the 90% particle size (D ₉₀ ) of the heat-expandable particles before expansion at 23 ° C. is more preferably 10 to 100 μm, still more preferably 15 to 75 μm, and even more preferably 20 to 50 μm. ..
The 90% particle size (D ₉₀ ) of the thermally expandable particles before expansion is measured using a laser diffraction type particle size distribution measuring device (manufactured by Malvern, product name "Mastersizer 3000") before expansion. In the particle distribution of the heat-expandable particles, it means the particle size in which the cumulative volume frequency calculated from the smaller particle size of the heat-expandable particles before expansion corresponds to 90%.

The maximum volume expansion coefficient of the thermally expandable particles when heated to a temperature equal to or higher than the expansion start temperature (t) of the thermally expandable particles used in one aspect of the present invention is preferably 1.5 to 200 times, more preferably. Is 2 to 150 times, more preferably 2.5 to 120 times, and even more preferably 3 to 100 times.

<Dielectric heating filler>
The dielectric heating filler used in the pressure-sensitive adhesive sheet of the present invention is at least one selected from the group consisting of metal oxides and semimetal carbonized metals.
The dielectric heating filler is a high frequency absorbing filler having a dielectric property capable of generating heat by applying a high frequency, and is, for example, a high frequency absorbing filler capable of generating heat by applying a high frequency such as a frequency of 27.12 MHz or 40.68 MHz. It is preferable to have.

As the dielectric heating filler, preferably, hydration of zinc oxide, titanium oxide, barium titanate, barium zirconate titanate, lead titanate, potassium niobate, hydrated aluminum silicate, alkali metal or alkaline earth metal. Examples thereof include metal oxides such as inorganic substances having crystalline water such as ammonium titanate, and metalloid carbides such as silicon carbide.
Among these, one or more selected from the group consisting of zinc oxide, titanium oxide, barium titanate and silicon carbide is preferable from the viewpoint of easy availability and good dielectric heat generation, and more preferably. One or more selected from the group consisting of zinc oxide, titanium oxide, and silicon carbide can be mentioned. Further, among these, zinc oxide is more preferable from the viewpoint of colorability and from the viewpoint of avoiding the possibility of deterioration of the resin used due to photocatalytic action when the layer (A) is a layer formed of a resin. Is. In addition, zinc oxide is abundant in variety, can be selected from various shapes and sizes, and can be suitably used from the viewpoint that the adhesiveness and mechanical properties of the pressure-sensitive adhesive sheet can be easily improved according to the application.
Examples of the titanium oxide include anatase-type titanium oxide, rutile-type titanium oxide, and brookite-type titanium oxide, and among these, anatase-type titanium oxide is preferable from the viewpoint of dielectric properties.

The average particle size of the dielectric heating filler used in one aspect of the present invention is preferably 1 to 30 μm.
When the average particle size is 1 μm or more, the distance that can be polarized inside the filler is increased, so that the degree of polarization is increased, the reversal motion when a high frequency is applied becomes intense, and dielectric heat is more easily generated, which is preferable. Further, when the average particle diameter is 30 μm or less, the distance from the surrounding dielectric heating filler is kept appropriate, and the distance between the dielectric heating fillers becomes too close to each other and is affected by each electric charge, and when a high frequency is applied. It is preferable from the viewpoint that it is possible to suppress a decrease in the reversal motion of the electric wave and the dielectric heat is easily generated.
From this point of view, the average particle size of the dielectric heating filler is more preferably 2 to 25 μm, still more preferably 3 to 20 μm, and even more preferably 5 to 15 μm.
The average particle size of the dielectric heating filler is a value of the volume average particle size calculated in accordance with JIS Z 8819-2: 2001 from the measurement result of the particle size distribution measured by the laser diffraction / scattering method. means.

[Structure of adhesive sheet]
Hereinafter, an example of the pressure-sensitive adhesive sheet, which is one aspect of the present invention, will be described with reference to each figure, but the pressure-sensitive adhesive sheet of the present invention is not limited to the following examples as long as the effects of the present invention are exhibited. No.
1 to 7 are schematic cross-sectional views of the pressure-sensitive adhesive sheets 10 to 70, respectively, showing an example of the structure of the pressure-sensitive adhesive sheet of the present invention.

As one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 10 shown in FIG. 1, the heat-expandable layer (A) is a heat-expandable pressure-sensitive adhesive layer (AX) (hereinafter, “layer (AX)””. It is also referred to as), and an adhesive sheet composed of a single layer (AX) can be mentioned.
In the case of the pressure-sensitive adhesive sheet 10 shown in FIG. 1, the layer (AX) contains the dielectric heating filler in addition to the heat-expandable particles. In this embodiment, for example, since the layer (AX) comes into direct contact with the adherend, the unevenness caused by the expansion of the heat-expandable particles in the layer (AX) does not go through the other layers. In addition, it becomes easy to form the pressure-sensitive adhesive sheet directly on the surface 1 that exhibits high-frequency peelability. As a result, it is preferable from the viewpoint that the high-frequency peelability of the pressure-sensitive adhesive sheet can be easily improved.
Further, in the pressure-sensitive adhesive sheet 10 shown in FIG. 1, a release material may be provided on one exposed surface of the layer (AX) (not shown), or a release material may be provided on both exposed surfaces (shown). figure).
Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, in the pressure-sensitive adhesive sheet 10 shown in FIG. 1, on one exposed surface and / or both exposed surfaces of the layer (AX) which is the layer (A). , A pressure-sensitive adhesive sheet having a non-thermally expandable pressure-sensitive adhesive layer (X2) described later may be used (not shown). In the pressure-sensitive adhesive sheet of this embodiment, a release material may be provided on the exposed surface of the layer (AX) and / or the non-thermally expandable pressure-sensitive adhesive layer (X2) (not shown).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 20 shown in FIG. 2, a layer (AX) having a support (Y) and being a layer (A), and a support (A). An adhesive sheet having a structure in which Y) and Y) are laminated in this order can be mentioned. In the case of the pressure-sensitive adhesive sheet 20 shown in FIG. 2, the layer (AX) also contains the dielectric heating filler in addition to the heat-expandable particles.
Further, in the pressure-sensitive adhesive sheet 20 shown in FIG. 2, a release material may be provided on the exposed surface of the layer (AX) and / or the exposed surface of the support (Y) (not shown).
Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, in the pressure-sensitive adhesive sheet 20 shown in FIG. 2, on the exposed surface of the layer (AX) which is the layer (A), a non-thermally expanding pressure-sensitive adhesive described later. It may be an adhesive sheet having a layer (X2) (not shown). In the pressure-sensitive adhesive sheet of this embodiment, a release material may be provided on the exposed surface of the non-thermally expandable pressure-sensitive adhesive layer (X2) and / or on the exposed surface of the support (Y) (not shown).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 30 shown in FIG. 3, a non-thermally expandable pressure-sensitive adhesive layer (X) that is not adjacent to the layer (A) (hereinafter, "layer (X)" ) ”), Examples of the pressure-sensitive adhesive sheet having a structure in which the non-thermally expandable pressure-sensitive adhesive layer (X1), the support (Y), and the layer (AX) are laminated in this order. In the case of the pressure-sensitive adhesive sheet 30 shown in FIG. 3, the layer (AX) also contains the dielectric heating filler in addition to the heat-expandable particles.
In the present specification, the layer (X) that is not adjacent to the layer (A) is also referred to as a non-thermally expandable pressure-sensitive adhesive layer (X1) (hereinafter, also referred to as “layer (X1)”).
Further, in the pressure-sensitive adhesive sheet 30 shown in FIG. 3, a release material may be provided on the exposed surface of the layer (AX) and / or the exposed surface of the layer (X1) (not shown).
Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, in the pressure-sensitive adhesive sheet 30 shown in FIG. It may be an adhesive sheet having a layer (X2) (not shown). In the pressure-sensitive adhesive sheet of the embodiment, a release material may be provided on the exposed surface of the non-thermally expandable pressure-sensitive adhesive layer (X2) and / or on the exposed surface of the layer (X1) (not shown).
Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, in the pressure-sensitive adhesive sheet 30 shown in FIG. 3, a double-sided heat-expandable pressure-sensitive adhesive sheet provided with a layer (AX) instead of the layer (X1) may be used (shown). figure). In this embodiment, the layers (AX) existing on both sides may have the same composition or different compositions. Further, a release material may be provided on one exposed surface of the layer (AX) existing on both sides (not shown), or a release material may be provided on both exposed surfaces (not shown). Further, in the present aspect, the pressure-sensitive adhesive sheet may have a non-thermally expandable pressure-sensitive adhesive layer (X2) described later on one exposed surface and / or both exposed surfaces of the layers (AX) existing on both sides. (Not shown). In the pressure-sensitive adhesive sheet of this embodiment, a release material may be provided on the exposed surface of the non-thermally expandable pressure-sensitive adhesive layer (X2) and / or on the exposed surface of the layer (AX) (not shown).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 40 shown in FIG. 4, a heat-expandable base material layer (AY) which is a layer (A) (hereinafter, “layer (AY)””. Also referred to as), and an adhesive sheet having a structure in which a non-thermally expandable layer (X) is laminated in this order can be mentioned.
Further, in the case of the pressure-sensitive adhesive sheet 40 shown in FIG. 4, it is preferable that the layer (AY) contains the dielectric heating filler in addition to the heat-expandable particles. In this embodiment, for example, since the layer (AY) which is the heat-expandable layer (A) does not directly contact the adherend, the heat-expandable particles or dielectric heat is generated from the layer (X) in contact with the adherend. It is preferable from the viewpoint that there is no risk of the filler or the like being detached or exposed on the surface, and the risk of contamination of the adherend by the heat-expandable particles or the dielectric heating filler can be reduced or prevented. Further, since the heat from the layer (AY) is not directly transferred to the adherend, it is preferable from the viewpoint that the heat history to the adherend can be suppressed.
Further, in the case of an adhesive sheet having a layer (AY), a layer (AY) which is a layer (A) and a non-heated layer (X) which is a layer (X) adjacent to the layer (A) as shown in the adhesive sheet 40 shown in FIG. It is preferable that the expandable pressure-sensitive adhesive layer (X2) is directly laminated in this order.
Here, "direct lamination" means, for example, in the case of the adhesive sheet 40 shown in FIG. 4, two layers are directly formed without having another layer between the layer (AY) and the layer (X2). Refers to the contacting configuration.
Further, in the present specification, the layer (X) adjacent to the layer (A) is also referred to as a non-thermally expandable pressure-sensitive adhesive layer (X2) (hereinafter, also referred to as "layer (X2)").
Since the layer (AY) and the layer (X2) are directly laminated in this order, a high frequency is applied to the pressure-sensitive adhesive sheet, and the heat-expandable particles expand to expand the surface of the layer (X2). When forming irregularities on the surface, the expansion of the heat-expandable particles in the layer (AY) may directly affect the surface 1 that exhibits the high-frequency peelability of the layer (X2) without going through another layer. It will be possible. As a result, it is preferable from the viewpoint that the high frequency peelability is more satisfactorily achieved.
Further, in the pressure-sensitive adhesive sheet 40 shown in FIG. 4, a release material may be provided on the exposed surface of the layer (X2) and / or the exposed surface of the layer (AY) (not shown).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 50 shown in FIG. 5, a support (Y), a layer (AY) which is a layer (A), and a layer (X) An adhesive sheet having a structure in which the above are laminated in this order can be mentioned. Also in the case of the pressure-sensitive adhesive sheet 50 shown in FIG. 5, it is preferable that the layer (AY) contains the dielectric heating filler in addition to the heat-expandable particles.
Further, in the case of the adhesive sheet 50 shown in FIG. 5, the layer (AY) and the layer (X) are directly laminated in this order from the same viewpoint as the above-mentioned reason for the adhesive sheet 40 shown in FIG. It is preferably an embodiment. That is, it is preferable that the layer (X) is the layer (X2).
Further, in the case of the pressure-sensitive adhesive sheet 50 shown in FIG. 5, it is preferable that the support (Y) and the layer (AY) are directly laminated in this order. Since the support (Y) and the layer (AY) are directly laminated, when the thermally expandable particles in the layer (AY) expand, the expansion on the support (Y) side is likely to be suppressed. Therefore, it is considered that the thermal expansion particles are more likely to expand toward the layer (X) side. As a result, the expansion caused by the heat-expanded particles tends to affect the surface 1 that exhibits the high-frequency peelability of the layer (X), which is more preferable from the viewpoint that the high-frequency peelability of the pressure-sensitive adhesive sheet is more likely to be exhibited.
Further, for the reason described above, in the case of the adhesive sheet 50 shown in FIG. 5, three layers of the support (Y), the layer (AY), and the layer (X2) are directly laminated in this order. More preferably. In the case of the adhesive sheet 50 shown in FIG. 5, "a mode in which three layers are directly laminated in this order" means that between the support (Y), the layer (AY), and the layer (X2). It refers to a configuration in which three layers are in direct contact with each other without having other layers.
Further, in the pressure-sensitive adhesive sheet 50 shown in FIG. 5, a release material may be provided on the exposed surface of the support (Y) and / or the exposed surface of the layer (X2) (not shown).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 60 shown in FIG. 6, a non-thermally expandable pressure-sensitive adhesive layer (X), a support (Y), and a layer (A) are used. Examples thereof include a pressure-sensitive adhesive sheet having a structure in which a certain layer (AY) and a first non-thermally expandable pressure-sensitive adhesive layer (X) are laminated in this order. Also in the case of the pressure-sensitive adhesive sheet 60 shown in FIG. 6, it is preferable that the layer (AY) contains the dielectric heating filler in addition to the heat-expandable particles.
Further, in the case of the adhesive sheet 60 shown in FIG. 6, the layer (X) located on the side opposite to the support (Y) of the layer (AY) from the same viewpoint as the above-mentioned reason for the adhesive sheet 40 shown in FIG. However, it is preferable that the layers are directly laminated in this order. That is, the layer (X) located on the opposite side of the layer (AY) from the support (Y) is the non-thermally expandable adhesive layer (X2) adjacent to the layer (AY) which is the layer (A). Is preferable. In this aspect, the layer (X2) has a surface 1 that exhibits high frequency exfoliation.
Further, in the case of the adhesive sheet 60 shown in FIG. 6, the support (Y) and the layer (AY) are directly laminated in this order from the same viewpoint as the above-mentioned reason for the adhesive sheet 50 shown in FIG. It is more preferable that the support (Y), the layer (AY), and the layer (X2) are directly laminated in this order.
Further, in the pressure-sensitive adhesive sheet 60 shown in FIG. 6, the layers (X) existing on both sides may have the same composition or different compositions. Further, a release material may be independently provided on the exposed surface of each layer (X) (not shown).
Further, in the pressure-sensitive adhesive sheet 60 shown in FIG. 6, as a double-sided heat-expandable pressure-sensitive adhesive sheet in which the layer (AY) which is the layer (A) and the layer (X1) which is not adjacent to the layer (X) are replaced with the layer (AX). It may be (not shown). In this embodiment, the layers (AX) existing on both sides may have the same composition or different compositions. Further, a release material may be independently provided on the exposed surface of each layer (AX) (not shown).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 70 shown in FIG. 7, a structure in which a layer (X), a layer (AY), and a layer (X) are laminated in this order. An adhesive sheet having the above can be mentioned. Also in the case of the pressure-sensitive adhesive sheet 70 shown in FIG. 7, it is preferable that the layer (AY) contains the dielectric heating filler in addition to the heat-expandable particles.
Further, in the case of the adhesive sheet 70 shown in FIG. 7, the layer (AY) and at least one of the layers (X) are arranged in this order from the same viewpoint as the above-mentioned reason for the adhesive sheet 40 shown in FIG. It is preferable that the layers are directly laminated with each other. That is, it is more preferable that at least one layer (X) of the layers (X) located on both sides of the layer (AY) is the layer (X2).
Further, in the case of the adhesive sheet 70 shown in FIG. 7, the adhesive sheet 40 shown in FIG. 4 has three layers of a layer (X), a layer (AY), and a layer (X) from the same viewpoint as described above. , It is more preferable that the layers are directly laminated in this order. That is, it is more preferable that both layers (X) located on both sides of the layer (AY) are layers (X2).
Further, in the pressure-sensitive adhesive sheet 70 shown in FIG. 7, the layers (X) existing on both sides may have the same composition or different compositions. Further, a release material may be independently provided on the exposed surface of each layer (X) (not shown).

Hereinafter, each layer described in the above-mentioned example of the pressure-sensitive adhesive sheet, which is one aspect of the present invention, will be described in sequence, but the pressure-sensitive adhesive sheet of the present invention is limited to the following examples as long as the effects of the present invention are exhibited. It's not a thing.

<Thermal expansion layer (A)>
The heat-expandable layer (A) is a layer containing at least the heat-expandable particles, and is preferably a heat-expandable pressure-sensitive adhesive layer (AX) or a heat-expandable base material layer (AY).

The content of the heat-expandable particles in the layer (A) is preferably 1 to 40% by mass, more preferably 3 to 35% by mass, still more preferably 5 to 5% of the total amount (100% by mass) of the layer (A). It is 30% by mass, more preferably 10 to 25% by mass.
When the content of the heat-expandable particles is 1% by mass or more, it is preferable from the viewpoint that when a high frequency is applied to the pressure-sensitive adhesive sheet, sufficient irregularities are formed on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet to easily improve the high-frequency peelability. .. Further, when the content of the heat-expandable particles is 40% by mass or less, from the viewpoint of improving the coatability of the coating film forming the layer (A), and the layer (A) before applying a high frequency to the pressure-sensitive adhesive sheet. ) It is preferable from the viewpoint of suppressing deterioration of the appearance of the surface and preventing embrittlement of the layer (A).

Further, the layer (A) preferably contains the dielectric heating filler. Since the layer (A) contains the dielectric heating filler together with the heat-expandable particles, the heat of the dielectric heating filler generated by applying a high frequency can be efficiently used for the expansion of the heat-expandable particles. .. Further, it is also preferable from the economical point of view that the content of the dielectric heating filler in the entire pressure-sensitive adhesive sheet can be reduced.
When the layer (A) contains a dielectric heating filler, the content of the dielectric heating filler in the layer (A) is preferably 1 to 30% by mass, more preferably 1 to 30% by mass, based on the total amount (100% by mass) of the layer (A). Is 3 to 25% by mass, more preferably 4 to 20% by mass, and even more preferably 6 to 18% by mass.
When the content of the dielectric heating filler is 1% by mass or more, it is preferable from the viewpoint that the high-frequency peelability of the pressure-sensitive adhesive sheet is easily improved. Further, when the content of the dielectric heating filler is 30% by mass or less, from the viewpoint of improving the coatability of the coating film forming the layer (A), and the layer (A) before applying a high frequency to the pressure-sensitive adhesive sheet. It is preferable from the viewpoint of suppressing deterioration of the appearance of the surface and preventing embrittlement of the layer (A).

Further, the layer (A) preferably contains a resin component.
Here, when the layer (A) contains a resin component and does not contain the dielectric heating filler, the content of the resin component in the layer (A) is preferably the total amount (100% by mass) of the layer (A). Is 50 to 99% by mass. When the content of the resin component is 50% by mass or more, it is preferable from the viewpoint of preventing embrittlement of the layer (A), and when the content of the resin component is 99% by mass or less, the obtained pressure-sensitive adhesive sheet is obtained. It is preferable from the viewpoint that it is possible to prevent the high frequency peeling property of the above from deteriorating. From this point of view, when the layer (A) contains the resin component and does not contain the dielectric heating filler, the content of the resin component in the layer (A) is the total amount (100% by mass) of the layer (A). Medium, more preferably 60 to 98% by mass, still more preferably 65 to 97% by mass, still more preferably 70 to 95% by mass, still more preferably 75 to 90% by mass.
When the layer (A) contains a resin component and also contains the dielectric heating filler, the content of the resin component in the layer (A) is preferably the total amount (100% by mass) of the layer (A). It is 50 to 98% by mass. When the content of the resin component is 50% by mass or more, it is preferable from the viewpoint of preventing embrittlement of the layer (A), and when the content of the resin component is 98% by mass or less, the obtained pressure-sensitive adhesive sheet is obtained. It is preferable from the viewpoint that it is possible to prevent the high frequency peeling property of the above from deteriorating. From this point of view, when the layer (A) contains a resin component and contains the dielectric heating filler, the content of the resin component in the layer (A) is the total amount (100% by mass) of the layer (A). Medium, more preferably 55 to 90% by mass, still more preferably 60 to 85% by mass, still more preferably 62 to 80% by mass.
The content of the resin component in the layer (A) is the content of the adhesive resin contained in the heat-expandable pressure-sensitive adhesive layer composition (ax) described later, or the heat-expandable base material composition (ay). ) Contains the resin content (when the heat-expandable base material composition (ay) is a solvent-free heat-expandable base material composition (ay'), the mass average molecular weight (Mw) is 50,000 or less. The total content of the oligomer having an ethylenically unsaturated group and the energy ray-polymerizable monomer) and the content of additives such as a cross-linking agent and a polymerization initiator which are added as necessary and react with those resins. Can be regarded as the total content of.

(Thickness of the thermally expandable layer (A) at 23 ° C.)
In one aspect of the present invention, the thickness of the layer (A) is preferably 20 to 2,000 μm, more preferably 20 to 1,000 μm, and even more preferably 20 to 500 μm.
When the thickness of the layer (A) is 20 μm or more, the layer (A) is easily formed, and unevenness is less likely to appear on the adhesive surface of the adhesive sheet having the formed layer (A) before high frequency application. This is preferable because sufficient adhesive force to the adherend can be easily obtained. Further, when the thickness of the layer (A) is 2,000 μm or less, the handleability when the layer (A) and the adhesive sheet having the layer (A) are wound in a roll shape is improved.
A more preferable range regarding the thickness of the layer (A) differs depending on whether the layer (A) is a heat-expandable pressure-sensitive adhesive layer (AX) or a heat-expandable base material layer (AY). Therefore, each suitable range will be described later.
The thickness of the layer (A) at 23 ° C. is a value measured by the method described in Examples described later.

(Thermal expansion adhesive layer (AX))
The heat-expandable pressure-sensitive adhesive layer (AX) that can be used in one aspect of the present invention is, for example, a composition (ax) for a heat-expandable pressure-sensitive adhesive layer containing at least the heat-expandable particles and containing a pressure-sensitive adhesive resin. Can be formed from.

In one aspect of the present invention, when the layer (A) is the layer (AX), the preferred range of the content of the heat-expandable particles in the layer (AX) is that of the heat-expandable particles in the layer (A). The content is the same as the above-mentioned range. The reason for setting the preferable range is also as described above.
Further, in one aspect of the present invention, when the layer (A) is the layer (AX) and contains the dielectric heating filler, the preferable range of the content of the dielectric heating filler in the layer (AX) is the layer (AX). The content of the dielectric heating filler in A) is the same as the above-mentioned range. The reason for setting the preferable range is also as described above.

In one aspect of the present invention, when the layer (A) is the layer (AX) and the layer (AX) does not contain the dielectric heating filler, the preferable range of the content of the resin component in the layer (AX) is. The content of the resin component in the layer (A) is the same as the above-mentioned range. The reason for setting the preferable range is also as described above.
Further, even when the layer (A) is the layer (AX) and the layer (AX) also contains the dielectric heating filler, the preferable range of the content of the resin component in the layer (AX) is the layer (A). The content of the resin component in) is the same as the above-mentioned range. The reason for setting the preferable range is also as described above.

In one aspect of the present invention, when the layer (A) is the layer (AX), the total content of the heat-expandable particles and the resin component in the layer (AX), and the dielectric heating filler added as needed, is In the total amount (100% by mass) of the layer (AX), preferably 60% by mass or more, more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably. It is 95% by mass or more, more preferably 98% by mass or more, and preferably 100% by mass or less.

[Composition for heat-expandable pressure-sensitive adhesive layer (ax)]
The layer (AX) is preferably formed from a heat-expandable pressure-sensitive adhesive layer composition (ax) (hereinafter, also simply referred to as “composition (ax)”) containing a pressure-sensitive adhesive resin. Hereinafter, preferred embodiments of the composition (ax) will be described.

When the layer (A) is the layer (AX), the content of the heat-expandable particles in the composition (ax) is preferably 1 in the total amount (100% by mass) of the active ingredients of the composition (ax). It is ~ 40% by mass, more preferably 3 to 35% by mass, still more preferably 5 to 30% by mass, still more preferably 10 to 25% by mass.
When the content of the heat-expandable particles is 1% by mass or more, it is preferable from the viewpoint that when a high frequency is applied to the pressure-sensitive adhesive sheet, sufficient unevenness is easily formed on the pressure-sensitive adhesive surface of the layer (AX). Further, when the content of the heat-expandable particles is 40% by mass or less, from the viewpoint of improving the coatability of the coating film forming the layer (AX), and the layer (AX) before applying high frequency to the pressure-sensitive adhesive sheet. ) It is preferable from the viewpoint of suppressing deterioration of the appearance of the surface and preventing embrittlement of the layer (AX).

When the layer (A) is the layer (AX) and the layer (AX) contains a dielectric heating filler, the content of the dielectric heating filler in the composition (ax) is that of the composition (ax). In the total amount (100% by mass) of the active ingredient, it is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, still more preferably 4 to 20% by mass, still more preferably 6 to 18% by mass.
When the content of the dielectric heating filler is 1% by mass or more, it is preferable from the viewpoint that the high-frequency peelability of the pressure-sensitive adhesive sheet is easily improved. Further, when the content of the dielectric heating filler is 30% by mass or less, from the viewpoint of improving the coatability of the coating film forming the layer (AX), and the layer (AX) before applying a high frequency to the pressure-sensitive adhesive sheet. It is preferable from the viewpoint of suppressing deterioration of the appearance of the surface and preventing embrittlement of the layer (AX).

Here, when the layer (A) is the layer (AX) and the layer (AX) does not contain the dielectric heating filler, the content of the adhesive resin in the composition (ax) is the composition (ax). ) Is preferably 50 to 99% by mass based on the total amount (100% by mass) of the active ingredient. It is preferable that the content of the adhesive resin is 50% by mass or more from the viewpoint of preventing embrittlement of the layer (AX), and it is obtained when the content of the adhesive resin is 99% by mass or less. This is preferable from the viewpoint of preventing the high frequency peelability of the pressure-sensitive adhesive sheet from deteriorating. From this point of view, when the layer (A) is the layer (AX) and the layer (AX) does not contain the dielectric heating filler, the content of the adhesive resin in the composition (ax) is the composition. Of the total amount (100% by mass) of the active ingredient of the substance (ax), more preferably 60 to 98% by mass, still more preferably 65 to 97% by mass, still more preferably 70 to 95% by mass, still more preferably 75 to 75 to%. It is 90% by mass.
When the layer (A) is the layer (AX) and the layer (A1) contains the dielectric heating filler, the content of the adhesive resin in the composition (ax) is the composition (ax). It is preferably 50 to 98% by mass in the total amount (100% by mass) of the active ingredient of. It is preferable that the content of the adhesive resin is 50% by mass or more from the viewpoint of preventing embrittlement of the layer (AX), and it is obtained when the content of the adhesive resin is 98% by mass or less. This is preferable from the viewpoint of preventing the high frequency peelability of the pressure-sensitive adhesive sheet from deteriorating. From this point of view, when the layer (A) is the layer (AX) and the layer (AX) contains the dielectric heating filler, the content of the adhesive resin in the composition (ax) is the composition. It is more preferably 55 to 90% by mass, still more preferably 60 to 85% by mass, and even more preferably 62 to 80% by mass, based on the total amount (100% by mass) of the active ingredient of the substance (ax).

{Adhesive resin}
Examples of the adhesive resin include polymers having adhesiveness by themselves and having a mass average molecular weight (Mw) of 10,000 or more.
The mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2 million, more preferably 20,000 to 1.5 million, still more preferably 30,000 to 100, from the viewpoint of improving the adhesive strength of the pressure-sensitive adhesive layer (A1). It is ten thousand.

Examples of the adhesive resin include rubber resins such as acrylic resins, urethane resins and polyisobutylene resins, polyester resins, olefin resins, silicone resins and polyvinyl ether resins.
These adhesive resins may be used alone or in combination of two or more.
When these adhesive resins are copolymers having two or more kinds of structural units, the form of the copolymer is not particularly limited, and block copolymers, random copolymers, and graft copolymers are used. It may be any of the polymers.

The adhesive resin may be an energy ray-curable adhesive resin in which a polymerizable functional group is introduced into the side chain.
Examples of the polymerizable functional group include those having a carbon-carbon double bond such as a (meth) acryloyl group, a vinyl group, and an allyl group.
Further, as the energy ray, among the above-mentioned ones, ultraviolet rays that are easy to handle are preferable.

Here, in one aspect of the present invention, it is preferable that the adhesive resin contains an acrylic resin from the viewpoint of facilitating the development of excellent adhesive force in the layer (AX).
The content of the acrylic resin in the adhesive resin is preferably 30 to 100% by mass, more preferably 50 to 100% by mass, based on the total amount (100% by mass) of the adhesive resin contained in the composition (ax). It is still more preferably 70 to 100% by mass, still more preferably 85 to 100% by mass, still more preferably 95 to 100% by mass, still more preferably 98 to 100% by mass, and even more preferably 100% by mass.

{{Acrylic resin}}
In one aspect of the present invention, the acrylic resin that can be used as an adhesive resin includes, for example, a polymer containing a structural unit derived from an alkyl (meth) acrylate having a linear or branched alkyl group, and a cyclic structure. Examples thereof include polymers containing a structural unit derived from (meth) acrylate having.

The mass average molecular weight (Mw) of the acrylic resin is preferably 100,000 to 1,500,000, more preferably 200,000 to 1,300,000, still more preferably 350,000 to 1,200,000, and even more preferably 500,000 to 1,100,000. ..

The acrylic resin used in one embodiment of the present invention includes a structural unit (m1) derived from an alkyl (meth) acrylate (m1') (hereinafter, also referred to as "monomer (m1')") and a functional group-containing monomer (m2). Acrylic copolymer (P1) having a structural unit (m2) derived from') (hereinafter, also referred to as "monomer (m2')") is more preferable.

The number of carbon atoms of the alkyl group contained in the monomer (m1') is preferably 1 to 24, more preferably 1 to 12, and even more preferably 2 to 10 from the viewpoint of exhibiting excellent adhesive strength in the layer (AX). , More preferably 4-8.
The alkyl group contained in the monomer (m1') may be a straight chain alkyl group or a branched chain alkyl group.

Examples of the monomer (m1') include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth). Examples thereof include acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, and stearyl (meth) acrylate.
One of these monomers (m1') may be used alone, or two or more thereof may be used in combination.
As the monomer (m1'), one selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth) acrylate. The above is preferable, and one or more selected from the group consisting of methyl (meth) acrylate, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate is more preferable, from butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate. One or more selected from the above group is more preferable.

The content of the structural unit (m1) is preferably 50 to 99.9% by mass, more preferably 60 to 99.0% by mass, based on the total structural unit (100% by mass) of the acrylic copolymer (P1). It is even more preferably 70 to 97.0% by mass, and even more preferably 80 to 95.0% by mass.

Examples of the functional group contained in the monomer (m2') include a hydroxy group, a carboxy group, an amino group, an epoxy group and the like.
That is, examples of the monomer (m2') include a hydroxy group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, and the like.
These monomers (m2') may be used alone or in combination of two or more.
Among these, as the monomer (m2'), a hydroxy group-containing monomer and a carboxy group-containing monomer are preferable, and a hydroxy group-containing monomer is more preferable.

Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl ( Hydroxyalkyl (meth) acrylates such as meta) acrylate and 4-hydroxybutyl (meth) acrylate; hydroxyl group-containing compounds such as unsaturated alcohols such as vinyl alcohol and allyl alcohol can be mentioned.

Examples of the carboxy group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citraconic acid, and their anhydrides. , 2- (Acryloyloxy) ethyl succinate, 2-carboxyethyl (meth) acrylate and the like.

The content of the structural unit (m2) is preferably 0.1 to 40% by mass in the total structural unit (100% by mass) of the acrylic copolymer (P1).
When the acrylic copolymer (P1) is not the acrylic copolymer (P2) described later, the content of the structural unit (m2) is the total structural unit (100% by mass) of the acrylic copolymer (P1). On the other hand, it is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, still more preferably 1.0 to 15% by mass, and even more preferably 3.0 to 10% by mass.
When the acrylic copolymer (P1) is an acrylic copolymer (P2) described later, the content of the structural unit (m2) is the total structural unit (100% by mass) of the acrylic copolymer (P1). However, the structural unit derived from the polymerizable compound (Q) described later is excluded.) Of the above, preferably 1.0 to 40% by mass, more preferably 5.0 to 35% by mass, still more preferably 10 to 30% by mass. Is.

The acrylic copolymer (P1) may further have a structural unit (m3) derived from a monomer (m3') other than the monomer (m1') and (m2').
In the acrylic copolymer (P1), the total content of the structural units (m1) and (m2) is preferably 70 to 70 in the total structural units (100% by mass) of the acrylic copolymer (P1). It is 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass, and even more preferably 98 to 100% by mass.

Examples of the monomer (m3') include olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene and chloroprene; cyclohexyl (meth) acrylate, It has a cyclic structure such as benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and imide (meth) acrylate. (Meta) Acrylate; Examples thereof include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, (meth) acrylamide, (meth) acrylonitrile, (meth) acryloylmorpholine, and N-vinylpyrrolidone.

Further, the acrylic copolymer (P1) may be an energy ray-curable acrylic copolymer (P2) in which a polymerizable functional group is introduced into at least one of the main chain and the side chain.
The acrylic copolymer (P2) is preferably an energy ray-curable acrylic copolymer in which a polymerizable functional group is introduced into the side chain.
The polymerizable functional group and the energy ray are as described above.
The polymerizable functional group reacts with the acrylic copolymer (P1) having the above-mentioned structural units (m1) and (m2) and the functional group of the structural unit (m2) of the acrylic copolymer. It can be introduced by reacting the obtained substituent (hereinafter, also simply referred to as “reactive substituent”) with the polymerizable compound (Q) having a polymerizable functional group.

The polymerizable compound (Q) is a compound having a polymerizable functional group and a reactive substituent.
As the polymerizable functional group, a (meth) acryloyl group is preferable. Further, the polymerizable compound (Q) is preferably a compound having 1 to 5 polymerizable functional groups per molecule.
The reactive substituent in the polymerizable compound (Q) may be appropriately changed according to the functional group of the monomer (m2), and examples thereof include an isocyanate group, a carboxyl group, an epoxy group and the like. From the viewpoint of the above, an isocyanate group is preferable. When the polymerizable compound (Q) has an isocyanate group, it can easily react with the acrylic copolymer (P1), for example, when the functional group of the monomer (m2') is a hydroxy group. ..

Examples of the polymerizable compound (Q) include (meth) acryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, (meth) acryloyl isocyanate, allyl isocyanate, glycidyl (meth) acrylate, and (meth). Acrylic acid and the like can be mentioned. These polymerizable compounds (Q) may be used alone or in combination of two or more.
Among these, (meth) acryloyl is a compound having an isocyanate group suitable as the reactive substituent and having an appropriate distance between the main chain and the carbon-carbon double bond group. Oxyethyl isocyanate is preferred.
The polymerizable compound (Q) is preferably 15 to 98 equivalents, more preferably 25 to 95 equivalents, and further, out of the total amount (100 equivalents) of the functional groups derived from the monomer (m2') in the acrylic copolymer (P1). Preferably 50 to 95 equivalents, even more preferably 60 to 90 equivalents, even more preferably 70 to 85 equivalents are reacted with the functional group derived from the monomer (m2').

{Energy ray curable compound}
In one aspect of the present invention, the composition (ax) may contain an energy ray-curable compound in addition to the adhesive resin. The energy ray-curable compound is preferably a monomer or oligomer which has an unsaturated group in the molecule and can be polymerized and cured by energy ray irradiation.
Examples of the energy ray-curable compound include trimethylpropantri (meth) acrylate, pentaerythritol (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1,4-butylene glycol. Polyvalent (meth) acrylate monomers such as di (meth) acrylate and 1,6-hexanediol (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, epoxy (meth) Examples thereof include oligomers such as acrylate.
Among these, urethane (meth) acrylate oligomers are preferable from the viewpoint of having a relatively high molecular weight and not easily lowering the elastic modulus of the layer (AX).
The molecular weight of the energy ray-curable compound (mass average molecular weight (Mw) in the case of an oligomer) is preferably 100 to 12,000, more preferably 200 to 10,000, still more preferably 400 to 8,000, and even more preferably. Is 600 to 6,000.

When the adhesive resin contains only a non-energy ray-curable adhesive resin, the content of the energy ray-curable compound in the composition (ax) is preferably 40 to 40 parts by mass with respect to 100 parts by mass of the adhesive resin. It is 200 parts by mass, more preferably 50 to 150 parts by mass, and even more preferably 60 to 90 parts by mass.
On the other hand, when the adhesive resin contains an energy ray-curable adhesive resin (for example, an acrylic copolymer (P2) or the like), the content of the energy ray-curable compound in the composition (ax) is adhesive. It is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and further preferably 3 to 15 parts by mass with respect to 100 parts by mass of the sex resin.

{Crosslinker}
In one aspect of the present invention, when the composition (ax) contains a tacky resin having a functional group like the above-mentioned acrylic copolymer (P1) or (P2), it further contains a cross-linking agent. Is preferable.
The cross-linking agent reacts with a pressure-sensitive adhesive resin having a functional group to cross-link the pressure-sensitive adhesive resins using the functional group as a cross-linking starting point.

Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and metal chelate-based cross-linking agents.
These cross-linking agents may be used alone or in combination of two or more.
Among these cross-linking agents, isocyanate-based cross-linking agents are preferable from the viewpoint of increasing the cohesive force to improve the adhesive force and the availability.

Examples of the isocyanate-based cross-linking agent include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; dicyclohexylmethane-4,4'-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, and cyclohexylene diisocyanate. Alicyclic polyisocyanates such as methylcyclohexylene diisocyanate, methylenebis (cyclohexyl isocyanate), 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate, hydrogenated xylylene diisocyanate; hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate Such as acyclic aliphatic polyisocyanates; and the like, polyisocyanate compounds and the like.
Examples of the isocyanate-based cross-linking agent include a trimethylolpropane adduct-type modified product of the polyvalent isocyanate compound, a burette-type modified product reacted with water, and an isocyanurate-type modified product containing an isocyanurate ring.

The content of the cross-linking agent in the composition (ax) is appropriately adjusted according to the number of functional groups of the adhesive resin, but is preferably 0 with respect to 100 parts by mass of the adhesive resin having functional groups. It is 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and further preferably 0.05 to 5 parts by mass.

{Photopolymerization initiator}
In one aspect of the present invention, when the composition (ax) contains an energy ray-curable adhesive resin and / or an energy ray-curable compound as the adhesive resin, it is preferable to further contain a photopolymerization initiator. .. In this aspect, the composition (ax) contains a photopolymerization initiator, so that the pressure-sensitive adhesive layer formed from the composition (ax) is sufficient even by irradiation with relatively low-energy energy rays. It is possible to proceed with the curing reaction and adjust the adhesive strength to a desired range.
Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanosen compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones. More specifically, examples of the photopolymerization initiator include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, benzoin, benzoin methyl ether, and benzoin ethyl. Ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthium monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloranthraquinone, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, etc. Can be mentioned.
These photopolymerization initiators may be used alone or in combination of two or more.
The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5.0 parts by mass, still more preferably, with respect to 100 parts by mass of the energy ray-curable adhesive resin. It is 0.05 to 3.0 parts by mass, more preferably 0.1 to 2.0 parts by mass.

{Adhesives}
In one aspect of the present invention, the composition (ax) may further contain a tackifier from the viewpoint of further improving the adhesive strength.
In the present specification, the "adhesive-imparting agent" refers to a component that supplementarily improves the adhesive strength of the adhesive resin and has a mass average molecular weight (Mw) of less than 10,000, and the above-mentioned adhesive resin. Is distinct from.
The mass average molecular weight (Mw) of the tackifier is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, and even more preferably 800 to 5,000.

As the tackifier, for example, a C5 fraction such as rosin-based resin, terpene-based resin, styrene-based resin, penten, isoprene, piperin, and 1,3-pentadiene produced by thermal decomposition of petroleum naphtha is copolymerized. Examples thereof include C5-based petroleum resin, C9-based petroleum resin obtained by copolymerizing C9 fractions such as inden and vinyl toluene produced by thermal decomposition of petroleum naphtha, and hydrides obtained by hydrogenating these.

The softening point of the tackifier is preferably 60 to 170 ° C, more preferably 65 to 160 ° C, and even more preferably 70 to 150 ° C.
In the present specification, the "softening point" of the tackifier means a value measured in accordance with JIS K 2531.
As the tackifier, one type may be used alone, or two or more types having different softening points, structures, etc. may be used in combination. When two or more kinds of tackifiers are used, it is preferable that the weighted average of the softening points of the plurality of tackifiers belongs to the above range.

When the composition (ax) contains a tackifier, the content of the tackifier is preferably 0.01 to 65% by mass, based on the total amount (100% by mass) of the active ingredient of the composition (ax). It is preferably 0.1 to 50% by mass, more preferably 1 to 40% by mass, and even more preferably 2 to 30% by mass.

{Adhesive additive}
In one aspect of the present invention, the composition (ax) contains an additive for a pressure-sensitive adhesive used in a general pressure-sensitive adhesive in addition to the above-mentioned additives as long as the effect of the present invention is not impaired. You may.
Examples of such additives for adhesives include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), ultraviolet absorbers and the like.
These adhesive additives may be used alone or in combination of two or more.

When the composition (ax) contains these adhesive additives, the content of each adhesive additive in the composition (ax) is independently increased to 100 parts by mass of the adhesive resin. On the other hand, it is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, and further preferably 0.01 to 6 parts by mass.

[Thickness of the heat-expandable pressure-sensitive adhesive layer (AX) at 23 ° C.]
In one aspect of the present invention, when the layer (A) is a layer (AX), the thickness of the layer (AX) at 23 ° C. develops good adhesive force and expands the heat-expandable particles by heating. From the viewpoint of forming unevenness on the adhesive surface of the layer (AX) satisfactorily, it is preferably 20 to 2,000 μm, more preferably 20 to 1,000 μm, still more preferably 20 to 500 μm, and even more preferably. It is 20 to 150 μm, more preferably 30 to 100 μm.
When the thickness of the layer (AX) is 20 μm or more, it becomes easy to form the layer (AX), and unevenness does not easily appear on the adhesive surface of the formed layer (AX) before high frequency application, and it is applied to the adherend. This is preferable because sufficient adhesive strength can be easily obtained. Further, when the thickness of the layer (AX) is 2,000 μm or less, the handleability when the adhesive sheet is wound in a roll shape is improved. Further, when the thickness of the layer (AX) is 150 μm or less, unevenness is more easily formed on the adhesive surface of the layer (AX) after application of high frequency, and high frequency peelability is improved, which is preferable.
The thickness of the layer (AX) at 23 ° C. is a value measured by the method described in Examples described later.

(Thermal expansion base layer (AY))
The heat-expandable substrate layer (AY) that can be used in one aspect of the present invention contains at least the heat-expandable particles. The layer (AY) is a non-adhesive substrate.
In the present specification, whether or not the layer is "non-adhesive" is determined when the probe tack value measured in accordance with JIS Z0237: 1991 with respect to the surface of the target layer is less than 50 mN / 5 mmφ. If so, the layer is determined to be "non-adhesive".
In the present specification, the specific method for measuring the probe tack value can be evaluated by the following method.

[Measurement method of probe tack value]
The layer to be measured was prepared on a light release film, cut into squares with a side of 10 mm, and then allowed to stand in an environment of 23 ° C. and 50% RH (relative humidity) for 24 hours to remove the light release film. Is used as a test sample.
The light release film was removed and exposed using a tacking tester (manufactured by Japanese Industrial Standards Co., Ltd., product name "NTS-4800") in an environment of 23 ° C. and 50% RH (relative humidity). The probe tack value on the surface of the test sample is measured according to JIS Z0237: 1991.
Specifically, a stainless steel probe having a diameter of 5 mm ^{is brought into contact with the surface of the test sample for 1 second with a contact load of 0.98 N / cm 2} , and then the probe is brought into contact with the test sample at a speed of 10 mm / sec. Measure the force required to move away from the surface of the steel. Then, the measured value is used as the probe tack value of the test sample.

In one aspect of the present invention, when the layer (A) is the layer (AY), the preferable range of the content of the heat-expandable fine particles in the layer (AY) is the content of the heat-expandable particles in the layer (A). The amount is the same as the above range. The reason for setting the preferable range is also as described above.
Further, in one aspect of the present invention, when the layer (A) is the layer (AY) and contains the dielectric heating filler, the preferable range of the content of the dielectric heating filler in the layer (AY) is the layer (AY). The content of the dielectric heating filler in A) is the same as the above-mentioned range. The reason for setting the preferable range is also as described above.

In one aspect of the present invention, when the layer (A) is the layer (AY) and the layer (AY) does not contain the dielectric heating filler, the preferable range of the content of the resin component in the layer (AY) is. The content of the resin component in the layer (A) is the same as the above-mentioned range.
Further, even when the layer (A) is the layer (AY) and the layer (AY) also contains the dielectric heating filler, the preferable range of the content of the resin component in the layer (AY) is the layer (A). The content of the resin component in) is the same as the above-mentioned range.

In one aspect of the present invention, when the layer (A) is the layer (AY), the total content of the heat-expandable particles and the resin component in the layer (AY) and the dielectric heating filler added as needed is In the total amount (100% by mass) of the layer (AY), preferably 60% by mass or more, more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably. It is 95% by mass or more, more preferably 98% by mass or more, and preferably 100% by mass or less.

From the viewpoint of improving the interlayer adhesion between the layer (AY) and other layers to be laminated, the surface of the layer (AY) is surface-treated by an oxidation method, an unevenness method, etc., an easy-adhesion treatment, or a primer. Treatment may be applied.
Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone, ultraviolet irradiation treatment and the like, and examples of the unevenness method include a sandblast method and a solvent treatment method. Can be mentioned.

[Composition for heat-expandable substrate layer (ay)]
The layer (AY) is a composition for a heat-expandable base material layer (ay) containing a resin for a heat-expandable base material layer (hereinafter, also simply referred to as a “resin for a base material layer”) and a heat-expandable particle. , Also referred to simply as "composition (ay)"). Hereinafter, preferred embodiments of the composition (ay) will be described.

When the layer (A) is a layer (AY), the content of the heat-expandable particles in the composition (ay) is preferably 1 in the total amount (100% by mass) of the active ingredients of the composition (ay). It is ~ 40% by mass, more preferably 3 to 35% by mass, still more preferably 5 to 30% by mass, still more preferably 10 to 25% by mass.
When the content of the heat-expandable particles is 1% by mass or more, when a high frequency is applied to the pressure-sensitive adhesive sheet, it becomes easy to form sufficient irregularities on the pressure-sensitive adhesive surface of the layer (X2) adjacent to the layer (AY). Is preferable. Further, when the content of the heat-expandable particles is 40% by mass or less, from the viewpoint of improving the coatability of the coating film forming the layer (AY), and the layer (AY) before applying high frequency to the pressure-sensitive adhesive sheet. ) Is preferable from the viewpoint of suppressing deterioration of the appearance of the surface of the layer (X2) and preventing embrittlement of the layer (AY).

When the layer (A) is a layer (AY) and the layer (AY) contains a dielectric heating filler, the content of the dielectric heating filler in the composition (ay) is the active ingredient of the composition (ay). Of the total amount (100% by mass), it is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, still more preferably 4 to 20% by mass, still more preferably 6 to 18% by mass.
When the content of the dielectric heating filler is 1% by mass or more, it is preferable from the viewpoint that the high-frequency peelability of the pressure-sensitive adhesive sheet is easily improved. Further, when the content of the dielectric heating filler is 30% by mass or less, from the viewpoint of improving the coatability of the coating film forming the layer (AY), and the layer (AY) before applying a high frequency to the pressure-sensitive adhesive sheet. It is preferable from the viewpoint of suppressing deterioration of the appearance of the surface of the layer (X2) adjacent to the layer (X2) and preventing embrittlement of the layer (AY).

Here, when the layer (A) is the layer (AY) and the layer (AY) does not contain the dielectric heating filler, the content of the resin for the base material layer in the composition (ay) is the composition. It is preferably 50 to 99% by mass in the total amount (100% by mass) of the active ingredient of (ay). When the content of the resin for the base material layer is 50% by mass or more, it is preferable from the viewpoint of preventing embrittlement of the layer (AY), and the content of the resin for the base material layer is 99% by mass or less. This is preferable from the viewpoint of preventing the high frequency peelability of the obtained adhesive sheet from deteriorating. From this point of view, when the layer (A) is the layer (AY) and the layer (AY) does not contain the dielectric heating filler, the content of the resin for the base material layer in the composition (ay) is , More preferably 60 to 98% by mass, still more preferably 65 to 97% by mass, still more preferably 70 to 95% by mass, still more preferably, based on the total amount (100% by mass) of the active ingredient of the composition (ay). It is 75 to 90% by mass.
When the layer (A) is the layer (AY) and the layer (AY) contains the dielectric heating filler, the content of the resin for the base material layer in the composition (ay) is the composition (AY). It is preferably 50 to 98% by mass based on the total amount (100% by mass) of the active ingredient of a). When the content of the resin for the base material layer is 50% by mass or more, it is preferable from the viewpoint of preventing embrittlement of the layer (AY), and the content of the resin for the base material layer is 98% by mass or less. This is preferable from the viewpoint of preventing the high frequency peelability of the obtained adhesive sheet from deteriorating. From this point of view, when the layer (A) is the layer (AY) and the layer (AY) contains the dielectric heating filler, the content of the resin for the base material layer in the composition (ay) is , More preferably 55 to 90% by mass, still more preferably 60 to 85% by mass, still more preferably 62 to 80% by mass, based on the total amount (100% by mass) of the active ingredient of the composition (ay).

{Resin for base material}
The resin for the base material layer contained in the composition (ay) which is the material for forming the layer (AY) may be a non-adhesive resin or an adhesive resin.
That is, even if the base material layer resin contained in the composition (ay) is an adhesive resin, the adhesive resin polymerizes with the polymerizable compound in the process of forming the layer (AY) from the composition (ay). It suffices that the resin component obtained by the reaction becomes a non-adhesive resin, and the layer (AY) containing the resin becomes non-adhesive.

The mass average molecular weight (Mw) of the resin for the base material layer contained in the composition (ay) is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, and further preferably 1,000 to 1,000. It is 500,000.
When the resin for the base material layer is a copolymer having two or more kinds of structural units, the form of the copolymer is not particularly limited, and the block copolymer, the random copolymer, and the graft are used together. It may be any of the polymers.

The base material layer resin contained in the composition (ay) preferably contains one or more selected from acrylic urethane-based resins and olefin-based resins.
Further, as the acrylic urethane resin, the following resin (U1) is preferable.
-Acrylic urethane resin (U1) obtained by polymerizing a urethane prepolymer (UP) and a vinyl compound containing a (meth) acrylic acid ester.
Here, in the present specification, the "prepolymer" means a compound obtained by polymerizing a monomer and capable of forming a polymer by further polymerization.

{{Acrylic urethane resin (U1)}}
Examples of the urethane prepolymer (UP) that serves as the main chain of the acrylic urethane resin (U1) include a reaction product of a polyol and a polyhydric isocyanate.
The urethane prepolymer (UP) is preferably obtained by further performing a chain extension reaction using a chain extender.

Examples of polyols used as raw materials for urethane prepolymers (UP) include alkylene-type polyols, ether-type polyols, ester-type polyols, esteramide-type polyols, ester-ether-type polyols, and carbonate-type polyols.
These polyols may be used alone or in combination of two or more.
As the polyol used in one embodiment of the present invention, diols are preferable, one or more selected from ester-type diols, alkylene-type diols and carbonate-type diols are more preferable, and one or more selected from ester-type diols and carbonate-type diols are more preferable. More preferred.

Examples of the ester-type diol include alkanediols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol; ethylene glycol, propylene glycol, and the like. One or more selected from diols such as diethylene glycol and alkylene glycol such as dipropylene glycol; and phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4-diphenyldicarboxylic acid, diphenylmethane-4 , 4'-dicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, hetic acid, maleic acid, fumaric acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexa Examples thereof include dicarboxylic acids such as hydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, and methylhexahydrophthalic acid, and one or more selected from these anhydrides.
Specifically, polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butyrene adipate diol, polybutylene hexamethylene adipate diol, Polydiethylene adipate diol, poly (polytetramethylene ether) adipate diol, poly (3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene sebacate diol, polyneo Examples thereof include pentyl terephthalate diol.

Examples of the alkylene-type diol include alkanediols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexanediol; ethylene glycol, propylene glycol, and the like. Examples thereof include alkylene glycols such as diethylene glycol and dipropylene glycol; polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polybutylene glycol; and polyoxyalkylene glycols such as polytetramethylene glycol.

Examples of the carbonate type diol include 1,4-tetramethylene carbonate diol, 1,5-pentamethylene carbonate diol, 1,6-hexamethylene carbonate diol, 1,2-propylene carbonate diol, and 1,3-propylene carbonate diol. , 2,2-Dimethylpropylene carbonate diol, 1,7-heptamethylene carbonate diol, 1,8-octamethylene carbonate diol, 1,4-cyclohexane carbonate diol and the like.

Examples of the polyisocyanate used as a raw material for the urethane prepolymer (UP) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.
One of these polyvalent isocyanates may be used alone, or two or more thereof may be used in combination.
Further, these polyvalent isocyanates may be a trimethylolpropane adduct-type modified product, a biuret-type modified product reacted with water, or an isocyanurate-type modified product containing an isocyanurate ring.
Among these, as the polyvalent isocyanate used in one embodiment of the present invention, diisocyanate is preferable, 4,4'-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6. -One or more selected from tolylene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), and alicyclic diisocyanate are more preferable.

Examples of the alicyclic diisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate (isophorone diisocyanate, IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexanediisocyanate, and 1,4-cyclohexane. Examples thereof include diisocyanate, methyl-2,4-cyclohexanediisocyanate and methyl-2,6-cyclohexanediisocyanate, but isophorone diisocyanate (IPDI) is preferable.

In one aspect of the present invention, the urethane prepolymer (UP) serving as the main chain of the acrylic urethane resin (U1) is a reaction product of a diol and a diisocyanate, and is a straight chain having ethylenically unsaturated groups at both ends. Urethane prepolymers are preferred.
As a method for introducing an ethylenically unsaturated group into both ends of the linear urethane prepolymer, an NCO group at the terminal of the linear urethane prepolymer formed by reacting a diol and a diisocyanate compound and a hydroxyalkyl (meth) acrylate are used. There is a method of reacting with.

Examples of the hydroxyalkyl (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxy. Examples thereof include butyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

The vinyl compound that forms the side chain of the acrylic urethane resin (U1) contains at least (meth) acrylic acid ester.
As the (meth) acrylic acid ester, one or more selected from alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate is preferable, and alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate are more preferably used in combination.

When the alkyl (meth) acrylate and the hydroxyalkyl (meth) acrylate are used in combination, the mixing ratio of the hydroxyalkyl (meth) acrylate to 100 parts by mass of the alkyl (meth) acrylate is preferably 0.1 to 99 parts by mass. It is preferably 0.5 to 30 parts by mass, more preferably 1.0 to 20 parts by mass, and even more preferably 1.5 to 10 parts by mass.

The alkyl group of the alkyl (meth) acrylate has preferably 1 to 24 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 1 to 8 carbon atoms, and even more preferably 1 to 3 carbon atoms.
Examples of the hydroxyalkyl (meth) acrylate include the same hydroxyalkyl (meth) acrylate used for introducing ethylenically unsaturated groups into both ends of the above-mentioned linear urethane prepolymer.

Examples of vinyl compounds other than (meth) acrylic acid ester include aromatic hydrocarbon-based vinyl compounds such as styrene, α-methylstyrene and vinyltoluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl acetate and vinyl propionate. , (Meta) acrylonitrile, N-vinylpyrrolidone, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, polar group-containing monomers such as meta (acrylamide); and the like.
One of these may be used alone, or two or more thereof may be used in combination.

The content of the (meth) acrylic acid ester in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass, still more preferably 80 to 80 to 100% by mass, based on the total amount (100% by mass) of the vinyl compound. It is 100% by mass, more preferably 90 to 100% by mass.

The total content of the alkyl (meth) acrylate and the hydroxyalkyl (meth) acrylate in the vinyl compound is preferably 40 to 100% by mass, more preferably 65 to 100% by mass, based on the total amount (100% by mass) of the vinyl compound. %, More preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.

The acrylic urethane resin (U1) used in one embodiment of the present invention is obtained by mixing a urethane prepolymer (UP) and a vinyl compound containing a (meth) acrylic acid ester and polymerizing both.
In the polymerization, it is preferable to further add a radical initiator.

In the acrylic urethane resin (U1) used in one aspect of the present invention, the content ratio of the structural unit (u11) derived from the urethane prepolymer (UP) and the structural unit (u12) derived from the vinyl compound [(u11). ) / (U12)] is preferably 10/90 to 80/20, more preferably 20/80 to 70/30, still more preferably 30/70 to 60/40, and even more preferably 35 in terms of mass ratio. / 65-55 / 45.

{{Olefin resin}}
The olefin-based resin suitable as the base material layer resin contained in the composition (ay) is a polymer having at least a structural unit derived from an olefin monomer.
The olefin monomer is preferably an α-olefin having 2 to 8 carbon atoms, and specific examples thereof include ethylene, propylene, butylene, isobutylene, and 1-hexene.
Among these, ethylene and propylene are preferable.

Specific olefinic resins, for example, ultra low density polyethylene (VLDPE, density: 880 kg / ^{m 3} or more 910 kg / ^m less than ^3), low density polyethylene (LDPE, density: 910 kg / ^{m 3} or more 915 kg / ^m less than ³ ), Medium density polyethylene (MDPE, density: 915 kg / m ³ or more and less than 942 kg / m ³ ), high density polyethylene (HDPE, density: 942 kg / m ³ or more), linear low density polyethylene and other polyethylene resins; polypropylene resin (PP); Polyethylene resin (PB); Ethylene-propylene copolymer; Olefin-based elastomer (TPO); Poly (4-methyl-1-pentene) (PMP); Polyethylene-vinyl acetate copolymer (EVA); Ethylene -Vinyl alcohol copolymer (EVOH); olefin-based ternary copolymer such as ethylene-propylene- (5-ethylidene-2-norbornene); and the like.

In one aspect of the present invention, the olefin resin may be a modified olefin resin further subjected to one or more modifications selected from acid modification, hydroxyl group modification and acrylic modification.
For example, the acid-modified olefin-based resin obtained by acid-modifying an olefin-based resin is a modified polymer obtained by graft-polymerizing an unsaturated carboxylic acid or an anhydride thereof with the above-mentioned non-modified olefin-based resin. Can be mentioned.
Examples of the unsaturated carboxylic acid or its anhydride include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth) acrylic acid, maleic anhydride, and itaconic anhydride. , Glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornendicarboxylic acid anhydride, tetrahydrophthalic anhydride and the like.
The unsaturated carboxylic acid or its anhydride may be used alone or in combination of two or more.

The acrylic-modified olefin-based resin obtained by subjecting the olefin-based resin to acrylic modification is a modification obtained by graft-polymerizing the above-mentioned non-modified olefin-based resin, which is the main chain, with an alkyl (meth) acrylate as a side chain. Examples include polymers.
The alkyl group of the above alkyl (meth) acrylate has preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and further preferably 1 to 12 carbon atoms.
Examples of the above-mentioned alkyl (meth) acrylate include the same compounds as those which can be selected as the above-mentioned monomer (m1').

Examples of the hydroxyl group-modified olefin resin obtained by subjecting the olefin resin to hydroxyl group modification include a modified polymer obtained by graft-polymerizing a hydroxyl group-containing compound on the above-mentioned non-modified olefin resin which is the main chain.
Examples of the above-mentioned hydroxyl group-containing compound include the same as the above-mentioned hydroxyl group-containing compound.

{{Resin other than acrylic urethane resin and olefin resin}}
In one aspect of the present invention, the composition (ay) may contain a resin for a base material layer other than the acrylic urethane-based resin and the olefin-based resin as long as the effects of the present invention are not impaired.
Examples of such a base material layer resin include vinyl resins such as polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene. -Styrene copolymer; cellulose triacetate; polycarbonate; polyurethane not applicable to acrylic urethane resin; polysulfone; polyether ether ketone; polyether sulfone; polyphenylene sulfide; polyimide resin such as polyetherimide and polyimide; polyamide resin Acrylic resin; Fluorine-based resin and the like.

However, from the viewpoint that the layer (AY) expands to facilitate the formation of irregularities on the adhesive surface of the non-thermally expandable pressure-sensitive adhesive layer (X), and from the viewpoint of improving the sheet shape retention after heat expansion, the composition The content of the resin for the base material layer other than the acrylic urethane resin and the olefin resin in (ay) is preferably small.
The content of the base material layer resin other than the acrylic urethane resin and the olefin resin is preferably less than 30 parts by mass with respect to 100 parts by mass of the total amount of the base material layer resin contained in the composition (ay). , More preferably less than 20 parts by mass, still more preferably less than 10 parts by mass, even more preferably less than 5 parts by mass, still more preferably less than 1 part by mass.

{Additives for base materials}
In one aspect of the present invention, the composition (ay) may contain an additive for a base material, if necessary, as long as the effects of the present invention are not impaired.
Examples of the base material additive include an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, and a colorant.
These base material additives may be used alone or in combination of two or more.
When these base material additives are contained, the content of each base material additive is preferably 0.0001 to 20% by mass with respect to 100 parts by mass of the base material layer resin. Parts, more preferably 0.001 to 10 parts by mass.

{Solvent-free heat-expandable substrate layer composition (ay')}
As one aspect of the composition (ay) used in one aspect of the present invention, an oligomer having an ethylenically unsaturated group having a mass average molecular weight (Mw) of 50,000 or less, an energy ray-polymerizable monomer, and the above-mentioned thermal expansion Examples thereof include a solvent-free heat-expandable base material composition (ay') containing sex particles and not containing a solvent (hereinafter, also simply referred to as “composition (ay')”).
In the composition (ay'), no solvent is blended, but the energy ray-polymerizable monomer contributes to the improvement of the plasticity of the oligomer.
By irradiating the composition (ay') with energy rays, oligomers having ethylenically unsaturated groups, energy ray-polymerizable monomers and the like are polymerized to form a layer (AY).

The types and amounts (contents) of the heat-expandable particles to be blended in the composition (ay') are as described above for the composition (ay'). The reason for setting the preferred mode and the preferred range is also as described above.
The type and amount (content) of the dielectric heating filler that may be blended in the composition (ay') are as described above for the composition (ay'). The reason for setting the preferred mode and the preferred range is also as described above.

The mass average molecular weight (Mw) of the oligomer contained in the composition (ay') is 50,000 or less, preferably 1,000 to 50,000, more preferably 2,000 to 40,000, and further. It is preferably 3,000 to 35,000, and even more preferably 4,000 to 30,000.

Further, the oligomer may be any resin contained in the above-mentioned composition (ay) having an ethylenically unsaturated group having a mass average molecular weight of 50,000 or less, as long as it is the above-mentioned urethane prepolymer (the above-mentioned urethane prepolymer). UP) is preferable, and a linear urethane prepolymer having ethylenically unsaturated groups at both ends is more preferable.
As the oligomer, a modified olefin resin having an ethylenically unsaturated group can also be used.

Examples of the energy ray-polymerizable monomer include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, and adamantan (adamantan). Alicyclic polymerizable compounds such as meta) acrylates and tricyclodecane acrylates; aromatic polymerizable compounds such as phenylhydroxypropyl acrylates, benzyl acrylates and phenolethylene oxide modified acrylates; tetrahydrofurfuryl (meth) acrylates, morpholine acrylates, N- Examples thereof include heterocyclic polymerizable compounds such as vinylpyrrolidone and N-vinylcaprolactam.
These energy ray-polymerizable monomers may be used alone or in combination of two or more.

The content ratio [oligomer / energy ray-polymerizable monomer] of the oligomer to the energy ray-polymerizable monomer in the composition (ay') is preferably 20/80 to 90/10 in terms of mass ratio. It is preferably 30/70 to 85/15, and more preferably 35/65 to 80/20.

In one aspect of the present invention, the composition (ay') is preferably further blended with a photopolymerization initiator.
By containing the photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with relatively low-energy energy rays.
Examples of the photopolymerization initiator include the same photopolymerization initiators that may be contained in the heat-expandable pressure-sensitive adhesive layer composition (ax), and one of these photopolymerization initiators is used alone. Or two or more of them may be used in combination.

The content of the photopolymerization initiator in the composition (ay') is preferably 0.01 to 5.0 parts by mass, more preferably 0.01 to 5.0 parts by mass, based on the total amount (100 parts by mass) of the oligomer and the energy ray-polymerizable monomer. Is 0.01 to 4.0 parts by mass, more preferably 0.02 to 3.0 parts by mass.

Here, when the layer (A) is the layer (AY) and the layer (AY) does not contain the dielectric heating filler, the total content of the oligomer and the energy ray-polymerizable monomer in the composition (ay') is contained. The amount is preferably 50 to 99% by mass based on the total amount (100% by mass) of the active ingredient of the composition (ay'). When the total content is 50% by mass or more, it is preferable from the viewpoint of preventing embrittlement of the layer (AY), and when the total content is 99% by mass or less, the high frequency peelability of the obtained adhesive sheet is obtained. It is preferable from the viewpoint that it can be prevented from deteriorating. From this point of view, when the layer (A) is the layer (AY) and the layer (AY) does not contain the dielectric heating filler, the oligomer and the energy ray-polymerizable monomer in the composition (ay') The total content is more preferably 60 to 98% by mass, still more preferably 65 to 97% by mass, still more preferably 70 to 95% by mass, based on the total amount (100% by mass) of the active ingredient of the composition (ay'). , Even more preferably 75 to 90% by mass.
When the layer (A) is the layer (AY) and the layer (AY) contains the dielectric heating filler, the total content of the oligomer and the energy ray-polymerizable monomer in the composition (ay'). Is preferably 50 to 98% by mass based on the total amount (100% by mass) of the active ingredient of the composition (ay'). When the total content is 50% by mass or more, it is preferable from the viewpoint of preventing embrittlement of the layer (AY), and when the total content is 98% by mass or less, the high frequency peelability of the obtained adhesive sheet is obtained. It is preferable from the viewpoint that it can be prevented from deteriorating. From this point of view, when the layer (A) is the layer (AY) and the layer (AY) contains the dielectric heating filler, the oligomer and the energy ray-polymerizable monomer in the composition (ay'). The total content is more preferably 55 to 90% by mass, still more preferably 60 to 85% by mass, still more preferably 62 to 80% by mass, based on the total amount (100% by mass) of the active ingredient of the composition (ay'). Is.

In one aspect of the present invention, the composition (ay') may contain the above-mentioned additives for a base material, if necessary, as long as the effects of the present invention are not impaired.
The base material additives may be used alone or in combination of two or more. When the base material additive is contained, the content of each base material additive is preferably 0, respectively, with respect to the total amount (100 parts by mass) of the oligomer and the energy ray-polymerizable monomer. It is 0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass.

[Thickness of the heat-expandable substrate layer (AY) at 23 ° C.]
In one aspect of the present invention, when the layer (A) is a layer (AY), the thickness of the layer (AY) is preferably 20 to 2,000, more preferably 20 to 1,000 μm, still more preferably. It is 20 to 500 μm, more preferably 25 to 400 μm, and even more preferably 30 to 300 μm.
When the thickness of the layer (AY) is 20 μm or more, the layer (AY) is easily formed, and unevenness is less likely to appear on the adhesive surface of the adhesive sheet having the formed layer (AY) before high frequency application. This is preferable because sufficient adhesive force to the adherend can be easily obtained. Further, when the thickness of the layer (AY) is 2,000 μm or less, the handleability when the layer (AY) and the adhesive sheet having the layer (AY) are wound in a roll shape is improved. Further, when the thickness of the layer (AY) is 500 μm or less, unevenness is more easily formed on the adhesive surface of the non-thermally expandable pressure-sensitive adhesive layer (X) after application of high frequency, and high frequency peelability is improved. It is preferable because it becomes good.
The thickness of the layer (AY) at 23 ° C. is a value measured by the method described in Examples described later.

(Non-thermally expandable adhesive layer (X))
The non-thermally expandable pressure-sensitive adhesive layer (X) that can be used in one aspect of the present invention is a pressure-sensitive adhesive layer other than the above-mentioned heat-expandable pressure-sensitive adhesive layer (AX).
The layer (X) preferably does not contain the heat-expandable particles, but may contain the heat-expandable particles within a range not contrary to the object of the present invention.
When the layer (X) contains the heat-expandable particles, the smaller the content, the more preferable, and the total amount (100% by mass) of the layer (X) is preferably less than 3% by mass, more preferably less than 1% by mass. , More preferably less than 0.1% by mass, even more preferably less than 0.01% by mass, even more preferably less than 0.001% by mass.
When the layer (X) contains the thermally expandable particles, the volume change rate (%) of the layer (X) calculated from the above formula is less than 5%, preferably less than 2%. It is preferably less than 1%, more preferably less than 0.1%, and even more preferably less than 0.01%.
Further, as described above, in the present specification, the layer not containing the heat-expandable particles is referred to as a “non-heat-expandable layer”. Therefore, even if the volume change rate (%) of the pressure-sensitive adhesive layer calculated from the above formula is 5% or more, if the pressure-sensitive adhesive layer does not contain the heat-expandable particles, the pressure-sensitive adhesive layer is a layer ( X).

The layer (X) that can be used in one aspect of the present invention preferably does not contain the dielectric heating filler, but may contain the dielectric heating filler within a range not contrary to the object of the present invention.
When the layer (X) contains the dielectric heating filler, the smaller the content, the more preferable, and it is preferably less than 1% by mass, more preferably 0.1% by mass, based on the total amount (100% by mass) of the layer (X). It is less than mass%, more preferably less than 0.01% by mass, even more preferably less than 0.001% by mass.

The layer (X) is preferably formed from the pressure-sensitive adhesive composition (x) containing the pressure-sensitive adhesive resin.
Examples of the pressure-sensitive adhesive composition (x) include the same ones as the heat-expandable pressure-sensitive adhesive layer composition (ax).
However, the content of the adhesive resin in the pressure-sensitive adhesive composition (x) is preferably 35 to 100% by mass, more preferably 50, based on the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition (x). ~ 100% by mass, more preferably 60 to 99.5% by mass, still more preferably 70 to 99.5% by mass, still more preferably 80 to 99.5% by mass, still more preferably 85 to 99.5% by mass. Is.

Further, the pressure-sensitive adhesive composition (x) preferably does not contain the heat-expandable particles, but may contain the heat-expandable particles within a range not contrary to the object of the present invention.
When the pressure-sensitive adhesive composition (x) contains the heat-expandable particles, the smaller the content is, the more preferable, and the content of the heat-expandable particles in the pressure-sensitive adhesive composition (x) is the pressure-sensitive adhesive composition (x). ) Of the total amount (100% by mass) of the active ingredient, preferably less than 3% by mass, more preferably less than 1% by mass, still more preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, and more. More preferably, it is less than 0.001% by mass.

Further, the pressure-sensitive adhesive composition (x) preferably does not contain the dielectric heating filler, but may contain the dielectric heating filler within a range not contrary to the object of the present invention.
When the pressure-sensitive adhesive composition (x) contains the dielectric heat-generating filler, it is preferable that the content thereof is small, and the content of the dielectric heat-generating filler in the pressure-sensitive adhesive composition (x) is that of the pressure-sensitive adhesive composition (x). In the total amount (100% by mass) of the active ingredient, it is less than 1% by mass, preferably less than 0.1% by mass, more preferably less than 0.01% by mass, and further preferably less than 0.001% by mass.
In particular, the layer (X) is affected by the layer (AY), such as the layer (X2) in FIG. 4 or 5, the layer (X2) in FIG. 6, and the layer (X2) in FIG. When the layer (X) has a surface 1 that receives and exhibits high-frequency peelability, it is preferable that the layer (X) does not contain the dielectric heating filler, and even if the dielectric heating filler is contained, the smaller the content, the more preferable. .. When the heat-expandable particles in the heat-expandable base material layer (AY) are expanded, the smaller the content of the dielectric heating filler in the layer (X), the less likely it is to inhibit the expansion of the heat-expandable particles. This is because unevenness can be satisfactorily formed on the surface 1 of the layer (X), which exhibits high-frequency peelability.

In one aspect of the present invention, the content of the resin in the layer (X) is preferably 35 to 100% by mass, more preferably 50 to 100% by mass, based on the total amount (100% by mass) of the layer (X). It is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, still more preferably 80 to 100% by mass, and even more preferably 85 to 100% by mass.

[Thickness of non-thermally expandable pressure-sensitive adhesive layer (X) at 23 ° C.]
In the pressure-sensitive adhesive sheet according to one aspect of the present invention, the thickness of the layer (X) at 23 ° C. is not particularly limited as long as the effect of the present invention is not impaired. In the case of a layer (X) having a surface 1 exhibiting high-frequency peelability, such as the layer (X2) in FIG. 5, the layer (X2) in FIG. 6, and the layer (X2) in FIG. 7, the following The range of is suitable.
When the layer (X) is a layer (X) having a surface 1 exhibiting high frequency peeling property (preferably, the layer (X) is a layer (X2) and having a surface 1 exhibiting high frequency peeling property (preferably a layer (X)). In the case of X)), the thickness of the layer (X) at 23 ° C. is preferably 2 to 10 μm, more preferably 3 to 8 μm, and even more preferably 3 to 7 μm.
When the layer (X) is used in the above embodiment, the thickness of the layer (X) at 23 ° C. is within the above range, so that good adhesive strength as an adhesive layer is exhibited and a heat-expandable base material layer is exhibited. It is preferable from the viewpoint that when the heat-expandable particles in (A2) are expanded, unevenness can be satisfactorily formed on the surface 1 that exhibits high-frequency peelability of the layer (X).

Further, in one aspect of the present invention, the thickness of the layer (X) at 23 ° C. is such that, for example, the layer (X) is the layer (X1) in FIG. 3 and the layer (X1) in FIG. In the case of the layer (X) having no surface 1 exhibiting high-frequency peelability, the following range is suitable.
When the layer (X) is a layer (X) that does not have a surface 1 that exhibits high-frequency peelability (preferably, the layer (X) is a layer (X1) and does not have a surface 1 that exhibits high-frequency peelability. The thickness of the layer (X) at 23 ° C. is preferably 2 to 150 μm, more preferably 3 to 125 μm. It is even more preferably 5 to 100 μm, even more preferably 8 to 80 μm, even more preferably 12 to 70 μm, and even more preferably 15 to 50 μm.
When the layer (X) is used in the above embodiment, if the thickness of the layer (X) at 23 ° C. is 2 μm or more, sufficient adhesive strength can be easily obtained, and unintentional peeling or adhesion from the adherend. There is a tendency to suppress the displacement of the body. On the other hand, if the thickness of the layer (X) at 23 ° C. is 150 μm or less, the pressure-sensitive adhesive sheet tends to be easy to handle.
The thickness of the layer (X) at 23 ° C. is a value measured by the method described in Examples described later.

(Support (Y))
The support (Y) that can be used in one aspect of the present invention is a non-thermally expandable layer. Further, the support (Y) is non-adhesive.
The support (Y) preferably does not contain the heat-expandable particles, but may contain the heat-expandable particles within a range not contrary to the object of the present invention. For example, by selecting the support resin contained in the support (Y), it is possible to adjust the volume change rate within the above range even if the heat-expandable particles are contained.
However, when the support (Y) contains the heat-expandable particles, the smaller the content, the more preferable, and the total amount (100% by mass) of the support (Y) is preferably less than 3% by mass, more preferably less than 3% by mass. It is less than 1% by mass, more preferably less than 0.1% by mass, still more preferably less than 0.01% by mass, still more preferably less than 0.001% by mass.
When the support (Y) contains the thermally expandable particles, the volume change rate (%) of the support (Y) calculated from the above formula is less than 5%, preferably less than 2%. , More preferably less than 1%, even more preferably less than 0.1%, even more preferably less than 0.01%.
Further, as described above, in the present specification, the layer not containing the heat-expandable particles is referred to as a “non-heat-expandable layer”. Therefore, even if the volume change rate (%) of the support calculated from the above formula is 5% or more, if the support does not contain the heat-expandable particles, the support is supported (Y). Suppose that

Further, the support (Y) preferably does not contain the dielectric heating filler, but may contain the dielectric heating filler within a range not contrary to the object of the present invention.
When the support (Y) contains the dielectric heating filler, the smaller the content, the more preferable, and the content is preferably less than 1% by mass, more preferably 0, based on the total amount (100% by mass) of the support (Y). .. Less than 1% by mass, more preferably less than 0.01% by mass, even more preferably less than 0.001% by mass.

Further, as the support (Y) that can be used in one aspect of the present invention, for example, in the pressure-sensitive adhesive sheets shown in FIGS. 2, 3, 5, and 6, the support (Y) contains the dielectric heating filler. However, it may be used as a layer that plays a role of heating the layer (A) (not shown).

Examples of the material for forming the support (Y) include a resin for a support, a metal, a paper material, and the like, and can be appropriately selected depending on the use of the obtained pressure-sensitive adhesive sheet.

Examples of the support resin used for the support (Y) include polyolefin resins such as polyethylene and polypropylene; polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol co-weight. Vinyl-based resins such as coalesced; polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resins such as polyurethane and acrylic-modified polyurethane; Polymethylpentene; polysulfone; polyether ether ketone; polyether sulfone; polyphenylene sulfide; polyimide-based resin such as polyetherimide and polyimide; polyamide-based resin; acrylic resin; fluorine-based resin and the like can be mentioned.
Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferable.
Examples of the support (Y) using the support resin as a forming material include a resin film or a resin sheet containing the support resin.
Examples of the metal include aluminum, tin, chromium, titanium and the like.
Examples of the paper material include thin paper, medium quality paper, high quality paper, impregnated paper, coated paper, art paper, sulfate paper, glassin paper, dust-free paper and the like.

These forming materials may be used alone or in combination of two or more.
Examples of the support (Y) in which two or more kinds of forming materials are combined include a paper material laminated with a thermoplastic resin such as polyethylene, a resin film containing a resin, or a sheet having a metal layer formed on the surface of the sheet. Can be mentioned.
Examples of the method for forming the metal layer include a method of depositing a metal by a PVD method such as vacuum deposition, sputtering, and ion plating, and a method of attaching a metal foil using a general adhesive.

Among these supports (Y), a resin film or sheet is preferable, a film or sheet made of polyester resin is more preferable, and a film or sheet made of polyethylene terephthalate (PET) is further preferable.

The content of the resin for the support in the support (Y) is preferably 60 to 100% by mass, more preferably 70 to 100% by mass, based on the total amount (100% by mass) of the support (Y). It is still more preferably 80 to 100% by mass, even more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, and even more preferably 98 to 100% by mass.

Further, the support (Y) may contain an additive for a support, if necessary, as long as the effects of the present invention are not impaired. Examples of the additive for the support include an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an anti-blocking agent, a colorant and the like.
These support additives may be used alone or in combination of two or more.
When these support additives are contained, the content of each support additive is preferably independent of 100 parts by mass of the support resin forming the support (Y). It is 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass.

Further, from the viewpoint of improving the interlayer adhesion with the other layers laminated on the support (Y), one surface of the support (Y) or both surfaces may be subjected to an oxidation method, an unevenness method, or the like. Surface treatment may be applied.
Examples of the oxidation method include a corona discharge treatment method, a plasma treatment method, a chromium acid oxidation (wet), a flame treatment method, a hot air treatment method, an ozone irradiation treatment method, an ultraviolet irradiation treatment method, and an ultraviolet-ozone treatment method. .. Further, as the unevenness method, for example, a sandblasting method, a solvent treatment method and the like can be mentioned.

Further, a primer layer, a sealing layer and the like may be provided on the surface of one or both of the supports (Y), if necessary.
Examples of the components constituting the primer layer include polyester-based resin, urethane-based resin, polyester-urethane-based resin, acrylic-based resin, and the like. One of these resins may be used alone, or two or more of these resins may be used alone. May be used together.
The sealing layer is used to further improve the adhesion between the support (Y) and the layer adjacent to the support (Y), or when the support (Y) is a support that is too flexible such as a paper material. Is provided to provide rigidity. The sealing layer is not particularly limited, but for example, a styrene-butadiene copolymer, an acrylic resin, a polyester resin, a polyurethane resin, a polystyrene resin, or the like is used as a main component, and clay or silica is used as necessary. , A layer made of a filler such as calcium carbonate added.
When these other layers are provided, their thicknesses are independently, preferably 0.05 to 30 μm, more preferably 0.1 to 5 μm, still more preferably 0.1 to 1 μm, still more preferably 0. It is 1 to 0.5 μm.

[Thickness of support (Y) at 23 ° C]
In one aspect of the present invention, the thickness of the support (Y) at 23 ° C. is appropriately set according to the use of the pressure-sensitive adhesive sheet, but is preferably 5 to 250 μm, more preferably from the viewpoint of handleability and economy. Is 10 to 200 μm, more preferably 25 to 150 μm.
The thickness of the support (Y) at 23 ° C. is a value measured by the method described in Examples described later.

(Release material)
As the release material that can be used in one aspect of the present invention, a release sheet that has been subjected to double-sided release treatment, a release sheet that has undergone single-sided release treatment, or the like is used, and a release agent is applied onto a base material for the release material. And so on.
Examples of the base material for the release material include a plastic film and a paper material. Examples of the plastic film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin; and olefin resin films such as polypropylene resin and polyethylene resin. Examples of paper materials include high-quality paper. , Glassin paper, kraft paper, etc.
Examples of the release agent include rubber-based elastomers such as isoprene-based resins and butadiene-based resins; silicone-based resins, olefin-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins. As the release agent, one type may be used alone, or two or more types may be used in combination.

The thickness of the release material is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 10 to 200 μm, more preferably 20 to 150 μm, and further preferably 35 to 80 μm.

The total thickness of the pressure-sensitive adhesive sheet at 23 ° C. (total thickness of each layer, excluding the release material) is appropriately set according to the use of the pressure-sensitive adhesive sheet, but is preferably 30 μm or more, more preferably 70 μm. Above, it is more preferably 95 μm or more, and preferably 300 μm or less, more preferably 200 μm or less, still more preferably 180 μm or less, still more preferably 175 μm or less.

Moreover, as one aspect of the pressure-sensitive adhesive sheet of the present invention, it is preferable that it does not contain a conductive substance. Examples of the conductive substance include simple metals such as carbon black, zinc, copper, titanium, and aluminum. The content of the conductive substance is preferably 5% by mass or less, more preferably 1% by mass or less, and 0.1% by mass, based on the total mass (100% by mass) of each layer independently. % Or less, more preferably 0.01% by mass or less, and even more preferably 0% by mass. When the content of the conductive substance is low, it becomes easy to prevent the occurrence of sparks when a high frequency is applied to the adhesive sheet and the occurrence of defects such as deterioration of the adhesive sheet and the adherend due to electrical dielectric breakdown.

[Manufacturing method of adhesive sheet]
The method for producing the pressure-sensitive adhesive sheet, which is one aspect of the present invention, is not particularly limited, and examples thereof include a method for manufacturing a pressure-sensitive adhesive sheet having at least the following step (1).
-Step (1): The composition for a heat-expandable pressure-sensitive adhesive layer (ax) is applied on the surface of the peeling material to be peeled off to form a coating film, and the coating film is dried or an energy ray is applied to the coating film. A step of irradiating to form a heat-expandable pressure-sensitive adhesive layer (AX) which is a heat-expandable layer (A).
When the composition (ax) contains the dielectric heating filler and only the step (1) is used, at least the pressure-sensitive adhesive sheet of the embodiment shown in FIG. 1 can be obtained.

Further, for example, as an example of the method for producing an adhesive sheet according to one aspect of the present invention shown in FIG. 2 described above, there is a method for producing an adhesive sheet having the following step (1a).
Step (1a): The composition (ax) is applied on the surface of one side of the support (Y) to form a coating film, the coating film is dried or the coating film is irradiated with energy rays, and heat is applied. A step of forming a heat-expandable pressure-sensitive adhesive layer (AX) which is an expandable layer (A).
Further, for example, as another aspect of the method for producing an adhesive sheet, which is one aspect of the present invention shown in FIG. 2, a method for producing an adhesive sheet having the following step (1a') can be mentioned.
-Step (1a'): A heat-expandable pressure-sensitive adhesive layer composition (ax) is applied onto the peeling-treated surface of the release material to form a coating film, and the coating film is dried or energy rays are applied to the coating film. Is irradiated to form a heat-expandable pressure-sensitive adhesive layer (AX) which is a heat-expandable layer (A), and the adhesive surface of the formed layer (AX) is attached to one surface of the support (Y). In addition, the process of obtaining an adhesive sheet.

Further, for example, as an example of the method for producing an adhesive sheet according to an aspect of the present invention shown in FIG. 3, the adhesive sheet having the following steps (2a) and (3a) in addition to the above step (1a). A manufacturing method can be mentioned.
Step (2a): The pressure-sensitive adhesive composition (x) is applied onto the peeling-treated surface of the release material to form a coating film, and the coating film is dried or irradiated with energy rays to the coating film to cause non-thermal expansion. A step of forming the sex adhesive layer (X).
Step (3a): An adhesive surface of the layer (X) formed in the step (2a) is formed on the surface of the support (Y) of the laminate obtained in the step (1a) on the opposite side of the layer (AX). A step of laminating to obtain a pressure-sensitive adhesive sheet having a non-thermally expandable pressure-sensitive adhesive layer (X1) that is not adjacent to the layer (AX).
Further, as another aspect of the method for producing an pressure-sensitive adhesive sheet, which is one aspect of the present invention shown in FIG. 3, for example, the pressure-sensitive adhesive sheet obtained by the same method as the above-mentioned steps (1a) or (1a'). The pressure-sensitive adhesive composition (x) is applied to the surface of the support (Y) opposite to the heat-expandable pressure-sensitive adhesive layer (AX) to form a coating film, and the coating film is dried or the coating film is applied. A method of irradiating the film with energy rays to obtain a pressure-sensitive adhesive sheet having a non-thermally expandable pressure-sensitive adhesive layer (X1) that is not adjacent to the layer (AX) may be used.

Further, for example, as an example of the method for producing an adhesive sheet according to one aspect of the present invention shown in FIG. 3 described above, there is a method for producing an adhesive sheet having the following steps (1b) to (3b).
Step (1b): The composition for a heat-expandable pressure-sensitive adhesive layer (ax) is applied on the surface of the peeling material to be peeled to form a coating film, and the coating film is dried or energy rays are applied to the coating film. A step of irradiating to form a heat-expandable pressure-sensitive adhesive layer (AX) which is a heat-expandable layer (A).
Step (2b): The pressure-sensitive adhesive composition (x) is applied on the peeling-treated surface of a peeling material different from the peeling material of step (1b) to form a coating film, and the coating film is dried or said. A step of irradiating a coating film with energy rays to form a non-thermally expandable pressure-sensitive adhesive layer (X).
-Step (3b): The adhesive surface of the layer (AX) formed in the step (1b) is attached to the surface of one side of the support (Y), and the side opposite to the layer (AX) of the support (Y). A step of laminating the adhesive surface of the layer (X) formed in the step (2b) to the surface to obtain a double-sided adhesive sheet having a non-thermally expandable adhesive layer (X1) not adjacent to the layer (AX).

Further, for example, as an example of the method for producing an adhesive sheet according to one aspect of the present invention shown in FIG. 3 described above, there is a method for producing an adhesive sheet having the following steps (1c) to (2c).
Step (1c): The pressure-sensitive adhesive composition (x) is applied onto the surface of one side of the support (Y) to form a coating film, and the coating film is dried or the coating film is irradiated with energy rays. , A step of forming a non-thermally expandable pressure-sensitive adhesive layer (X).
Step (2c): The composition (ax) for a heat-expandable pressure-sensitive adhesive layer is applied to the surface of the support (Y) of the laminate obtained in step (1c) on the opposite side of the layer (X). To form a coating film, the coating film is dried or the coating film is irradiated with energy rays to form a heat-expandable pressure-sensitive adhesive layer (AX) which is a heat-expandable layer (A), and the layer (AX) is formed. A step of obtaining a pressure-sensitive adhesive sheet having a non-thermally expandable pressure-sensitive adhesive layer (X1) that is not adjacent to the pressure-sensitive adhesive layer (X1).
Here, with respect to the manufacturing method having the step (1c) and the step (2c), the order of the layers (X) and the layers (AX) formed on the support (Y) may be reversed, but the layer (AX) may be reversed. ) Is formed first, and then the layer (X) is formed by drying. It is necessary to dry the film, which limits the composition of the layer (X) that can be formed. Therefore, when the layer (X) is formed by drying, it is desirable to use a method in which the layer (X) is formed first and then the layer (AX) is formed.
Also in each of the production methods described below, the layer (A) contains the drying treatment performed for the purpose of forming another layer at the same time as the formation of the thermally expandable layer (A) or after the formation of the layer (A). Similarly, it is necessary to carry out the process at a temperature lower than the expansion start temperature (t) of the thermally expandable particles.

Further, for example, as an example of the method for producing an adhesive sheet according to one aspect of the present invention shown in FIG. 4 described above, there is a method for producing an adhesive sheet having the following steps (1d) to (3d).
Step (1d): A heat-expandable substrate layer composition (ay) is applied onto the peeling-treated surface of the release material to form a coating film, and the coating film is dried or an energy ray is applied to the coating film. A step of irradiating to form a heat-expandable substrate layer (AY).
Step (2d): The pressure-sensitive adhesive composition (x) is applied on the peeling treatment surface of a peeling material different from the peeling material used in the step (1d) to form a coating film, and the coating film is dried. Alternatively, a step of irradiating the coating film with energy rays to form a non-thermally expandable pressure-sensitive adhesive layer (X).
Step (3d): The surface on the layer (AY) side formed in the step (1d) and the adhesive surface of the layer (X) formed in the step (2d) are bonded together to form a non-adhesive surface adjacent to the layer (AY). A step of obtaining a pressure-sensitive adhesive sheet having a heat-expandable pressure-sensitive adhesive layer (X2).
Further, as another aspect of the method for producing an adhesive sheet, which is one aspect of the present invention shown in FIG. 4, for example, the heat-expandable base material layer (AY) obtained by the same method as the above-mentioned step (1d). ), The pressure-sensitive adhesive composition (x) is applied to the surface opposite to the release material to form a coating film, and the coating film is dried or the coating film is irradiated with energy rays to form a layer (AY). ) And a non-heat-expandable pressure-sensitive adhesive layer (X2) adjacent to the) may be used as a method for obtaining a pressure-sensitive adhesive sheet.

Further, for example, as an example of the method for producing an adhesive sheet according to one aspect of the present invention shown in FIG. 7, the following steps (4d) to (5d) are included in addition to the above steps (1d) to (3d). , A method for manufacturing an adhesive sheet. In the manufacturing method, the non-thermally expandable pressure-sensitive adhesive layer (X) formed in the above step (2d) is referred to as a first non-heat-expandable pressure-sensitive adhesive layer (X).
Step (4d): The pressure-sensitive adhesive composition (x) is applied on the peeling treatment surface of a peeling material different from the peeling material used in the step (2d) to form a coating film, and the coating film is dried. Alternatively, a step of irradiating the coating film with energy rays to form a second non-thermally expandable pressure-sensitive adhesive layer (X).
Step (5d): A second non-thermally expandable pressure-sensitive adhesive layer formed in step (4d) on the surface opposite to the layer (X2) of the pressure-sensitive adhesive sheet layer (AY) formed in step (3d). A step of laminating the adhesive surfaces of (X) to obtain a double-sided adhesive sheet having a non-thermally expandable adhesive layer (X2) adjacent to the layer (AY) on both sides of the layer (AY).
Further, as another aspect of the pressure-sensitive adhesive sheet manufacturing method which is one aspect of the present invention shown in FIG. 7 described above, for example, another aspect of the pressure-sensitive adhesive sheet manufacturing method which is one aspect of the present invention shown in FIG. 4 described above. The pressure-sensitive adhesive composition (x) is applied to the surface of the pressure-sensitive adhesive sheet layer (AY) opposite to the layer (X2) to form a coating film, and the coating film is dried or said. A method of irradiating the coating film with energy rays to obtain a double-sided pressure-sensitive adhesive sheet having a non-thermally expandable pressure-sensitive adhesive layer (X2) adjacent to the layer (AY) on both sides of the layer (AY) may be used.

Further, for example, as an example of the method for producing an adhesive sheet according to one aspect of the present invention shown in FIG. 5, there is a method for producing an adhesive sheet having the following steps (1f) to (3f).
Step (1f): The pressure-sensitive adhesive composition (x) is applied onto the peeling treatment surface of the release material to form a coating film, the coating film is dried or the coating film is irradiated with energy rays, and non-heat is applied. A step of forming the expansive pressure-sensitive adhesive layer (X).
Step (2f): A heat-expandable substrate layer composition (ay) is applied to one side of the support (Y) to form a coating film, and the coating film is dried or an energy ray is applied to the coating film. A step of irradiating and forming a base material laminate in which a support (Y) and a heat-expandable base material layer (AY) are laminated (preferably directly laminated).
Step (3f): The adhesive surface of the layer (X) formed in the step (1f) and the surface of the base material laminate formed in the step (2f) on the layer (AY) side are bonded together to form a layer (AY). ) And an adhesive sheet having a non-thermally expandable adhesive layer (X2) adjacent to the above.
Further, as another aspect of the method for producing an adhesive sheet, which is one aspect of the present invention shown in FIG. 5, for example, a support for a layer (AY) of a base material laminate obtained in the step (2f) The pressure-sensitive adhesive composition (x) is applied to the surface opposite to Y) to form a coating film, and the coating film is dried or the coating film is irradiated with energy rays to form a support (Y). And, as a method of obtaining a pressure-sensitive adhesive sheet having a layer (AY) and a non-thermally expandable pressure-sensitive adhesive layer (X2) adjacent to the layer (AY).

Further, for example, as an example of the method for producing an adhesive sheet according to one aspect of the present invention shown in FIG. 6, the following steps (4f) to (5f) are included in addition to the above steps (1f) to (3f). , A method for manufacturing an adhesive sheet. In the manufacturing method, the non-thermally expandable pressure-sensitive adhesive layer (X) formed in the above step (1f) is referred to as a first non-heat-expandable pressure-sensitive adhesive layer (X).
-Step (4f): The pressure-sensitive adhesive composition (x) is applied on the peeling-treated surface of a peeling material different from the peeling material used in the step (1f) to form a coating film, and the coating film is dried. Alternatively, a step of irradiating the coating film with energy rays to form a second non-thermally expandable pressure-sensitive adhesive layer (X).
-Step (5f): Formed in step (4f) on the surface of the support (Y) of the pressure-sensitive adhesive sheet formed in step (3f) opposite to the layer (X2) and the heat-expandable base material layer (AY). The adhesive surface of the second non-thermally expandable pressure-sensitive adhesive layer (X) is bonded to each other, and the non-heat-expandable pressure-sensitive adhesive layer (X2) adjacent to the layer (AY), the layer (AY), and the support ( A step of obtaining a double-sided pressure-sensitive adhesive sheet having Y) and a non-thermally expandable pressure-sensitive adhesive layer (X1) that is not adjacent to the layer (AY) in this order.
Further, as another aspect of the method for producing the pressure-sensitive adhesive sheet, which is one aspect of the present invention shown in FIG. 6, for example, the production of another aspect of the pressure-sensitive adhesive sheet, which is one aspect of the present invention shown in FIG. The pressure-sensitive adhesive composition (x) is applied to the surface opposite to the layer (X2) and the layer (AY) of the support (Y) of the pressure-sensitive adhesive sheet obtained by the method to form a coating film. The coating film is dried or irradiated with energy rays, and the non-heat-expandable pressure-sensitive adhesive layer (X2) adjacent to the layer (AY), the layer (AY), the support (Y), and the layer ( AY) may be used as a method for obtaining a double-sided pressure-sensitive adhesive sheet having a non-thermally expandable pressure-sensitive adhesive layer (X1) adjacent to each other in this order.

Further, in the above-mentioned method for producing an adhesive sheet, the heat-expandable pressure-sensitive adhesive layer composition (ax), the heat-expandable base material layer composition (ay), and the pressure-sensitive adhesive composition (x) are independent of each other. , Further, a diluting solvent may be blended, and each of the above compositions may be in the form of a solution.
Examples of the diluting solvent used include organic solvents such as methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol.
As these organic solvents, the organic solvent used in the production of each component contained in each of the compositions may be used as it is, or one or more other organic solvents may be added.
The concentration of the active ingredient in the solution of each composition is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, and further preferably 15 to 45% by mass, respectively.
Examples of the coating method include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like.

Further, the steps of drying the coating film formed from the composition for the heat-expandable pressure-sensitive adhesive layer (ax), the composition for the heat-expandable base material layer (ay), and the pressure-sensitive adhesive composition (x) are independent of each other. In addition, when drying together with a coating film and / or a layer formed from a composition containing thermal expansion particles, the drying temperature is set to the expansion start temperature of the thermal expansion particles from the viewpoint of suppressing the expansion of the thermal expansion particles. It is preferably performed with less than (t).
On the other hand, when only the coating film formed from the composition (x) containing no heat-expandable particles is dried among the composition (x), the drying temperature is particularly limited as long as a desired layer can be formed. Although not, it is preferably 60 to 150 ° C, more preferably 70 to 140 ° C, and even more preferably 75 to 130 ° C.
Further, regardless of whether or not the coating film contains thermally expandable particles, the drying time of the coating film is not particularly limited as long as a desired layer can be formed, but each is independently, preferably 30 seconds to 5 minutes. ..
The method for producing an adhesive sheet, which is one aspect of the present invention, is not limited to the above-mentioned example.

[Use of adhesive sheet]
The pressure-sensitive adhesive sheet, which is one aspect of the present invention, has sufficient adhesive strength when attached to an adherend, but can be easily peeled off by applying a high frequency when peeling from the adherend. Therefore, as long as an adherend that can be used in an environment where a high frequency is applied is used, it can be applied to all applications.
The adherend is not particularly limited, but a brittle material is mentioned as a preferable embodiment of the adherend from the viewpoint that the adhesive sheet has high frequency peelability and can reduce the load applied to the adherend at the time of peeling. Be done. Preferable examples of the brittle material include wafers for electronic devices, which will be described later.
Further, the adhesive sheet is suitable from the viewpoint that the adhesive sheet has high-frequency peelability and can be expected to suppress or prevent defects such as contamination, deformation, and breakage of the adherend caused by the adhesive sheet. One embodiment includes materials for electronic devices.
Examples of the material for electronic devices include chips for electronic devices such as semiconductor chips, wafers for electronic devices such as semiconductor wafers, compound semiconductors, packages for electronic devices such as semiconductor packages, electronic components, sapphire substrates, displays, and panels. Examples include a substrate. Of these, wafers for electronic devices are more preferred.

Further, the pressure-sensitive adhesive sheet according to one aspect of the present invention can be used as a temporary fixing sheet, for example, in the manufacturing process of a material for an electronic device as described above. Specific examples of the adhesive sheet in such a usage mode include a step of grinding an adherend such as a dicing sheet and an electronic device wafer used when dicing an adherend such as a wafer for an electronic device. Temporary fixing sheet used to temporarily fix the support for supporting the back grind sheet to which an adherend such as a wafer for electronic devices is attached, and for electronic devices individualized by dicing. Expanding tape used to increase the distance between adherends such as chips, transfer tape used to invert the front and back of adherends such as chips for electronic devices, and temporary fixing for inspecting inspection objects. A suitable example is a sheet for use.
Therefore, the pressure-sensitive adhesive sheet according to one aspect of the present invention can be suitably used as a temporary fixing pressure-sensitive adhesive sheet used for processing and / or inspecting materials for electronic devices.

Further, since the pressure-sensitive adhesive sheet according to one aspect of the present invention has high-frequency peelability and can be easily peeled off from the adherend, contamination, deformation, and deformation of the adherend caused by the pressure-sensitive adhesive sheet. It can be expected to suppress and prevent problems such as breakage. Therefore, as an application of the adhesive sheet, which is one aspect of the present invention, in addition to materials for electronic devices, for example, protective film applications such as window films, protective / design-imparting applications such as wallpaper and wrapping films, and returnable labels There are various uses such as various label uses such as, and use when attaching temporary notices and the like.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to the following examples. The physical property values in the following examples are values measured by the following methods.

[Mass average molecular weight (Mw)]
It was measured under the following conditions using a gel permeation chromatograph device (manufactured by Tosoh Corporation, product name "HLC-8020"), and the value measured in terms of standard polystyrene was used.
(Measurement condition)
-Column: "TSK guard volume HXL-L", "TSK gel G2500HXL", "TSK gel G2000HXL", and "TSK gel G1000HXL" (all manufactured by Tosoh Corporation) are connected in sequence.-Column temperature: 40 ° C.
・ Developing solvent: tetrahydrofuran ・ Flow rate: 1.0 mL / min

[Thickness of each layer]
It was measured under the condition of 23 ° C. using a constant pressure thickness measuring instrument (model number: "PG-02J", standard: JIS K6783, Z1702, Z1709 compliant) manufactured by Teclock Co., Ltd.

[Average particle size of thermally expandable particles (D ₅₀ ), 90% particle size (D ₉₀ )]
The particle distribution of the thermally expandable particles before expansion at 23 ° C. was measured using a laser diffraction type particle size distribution measuring device (manufactured by Malvern, product name “Master Sizar 3000”).
Then, the particle diameters corresponding to the cumulative volume frequencies of 50% and 90% calculated from the smaller particle diameter of the particle distribution are set to "average particle diameter of thermally expandable particles (D ₅₀ )" and "expandable particles", respectively. 90% particle size (D ₉₀ ) ”.

[Average particle size of dielectric heating filler]
The particle size distribution of the dielectric heating filler was measured by the laser diffraction / scattering method. From the result of particle size distribution measurement, the volume average particle size was calculated according to JIS Z 8819-2: 2001.

The details of the materials used to form each layer in the following production examples and examples are as follows.

<Solution containing adhesive resin>
-Solution containing acrylic copolymer (P1): n-butyl acrylate (BA) / methyl methacrylate (MMA) / acrylic acid (AA) / 2-hydroxyethyl acrylate (HEA) = 86/8/1/5 ( A solution containing an acrylic copolymer of Mw 600,000 having a constituent unit derived from a raw material monomer consisting of (mass ratio) (diluting solvent: ethyl acetate, active ingredient concentration (resin content in solution): 40% by mass)
-Solution containing acrylic copolymer (P2)): Raw material monomer consisting of n-butyl acrylate (BA) / methyl methacrylate (MMA) / 2-hydroxyethyl acrylate (HEA) = 52/20/28 (mass ratio) 2-methacryloyloxyethyl isocyanate (MOI) was reacted with an acrylic copolymer having a structural unit derived from the above so that the addition rate with respect to all the hydroxy groups in the acrylic copolymer was 90% based on the number of moles. A solution containing an energy ray-curable acrylic copolymer of Mw 500,000 (diluting solvent: ethyl acetate, active ingredient concentration (resin content in the solution): 35% by mass)

<Additives>
-Isocyanate-based cross-linking agent (i): manufactured by Tosoh Corporation, product name "Coronate (registered trademark) L", active ingredient concentration: 75% by mass
-Isocyanate-based cross-linking agent (ii): manufactured by Tosoh Corporation, product name "Coronate (registered trademark) HX", active ingredient concentration: 100% by mass
-Energy ray-curable compound (i): manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "Shikou UT-4332", polyfunctional urethane acrylate-photopolymerization initiator (i): bis (2,4,6-trimethylbenzoyl) ) Phenylphosphine oxide / photopolymerization initiator (ii): 1-hydroxycyclohexylphenylketone / phthalocyanine pigment

<Thermal expandable particles>
-Thermal expandable particles (i): manufactured by Nouryon, product name "Expancel (registered trademark) 031-40" (DU type), expansion start temperature (t) = 88 ° C., average particle size (D ₅₀ ) = 12. 6 μm, 90% particle size (D ₉₀ ) = 26.2 μm
-Heat-expandable particles (ii): manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., product name "Matsumoto Microsphere (registered trademark) FN-190SSD", expansion start temperature (t) = 181 ° C, average particle size (D ₅₀ ) = 16.2 μm, 90% particle size (D ₉₀ ) = 26.3 μm

<Dielectric heating filler>
-Zinc oxide: manufactured by Sakai Chemical Industry Co., Ltd., product name "LPZINC11", average particle size = 11 μm
-Zinc: Made by Fujifilm Wako Pure Chemical Industries, Ltd., product name "Zinc, powder", average particle size = 9 μm

<Release material>
-Heavy release film: Made by Lintec Corporation, product name "SP-PET382150", polyethylene terephthalate (PET) film with a release agent layer formed from a silicone-based release agent on one side, thickness: 38 μm
-Light release film: manufactured by Lintec Corporation, product name "SP-PET381031", PET film with a release agent layer formed from a silicone-based release agent on one side, thickness: 38 μm

Production Example 1 (Formation of a laminated body in which a heavy-release film, a heat-expandable pressure-sensitive adhesive layer (AX), and a support (Y) are laminated)
0.74 parts by mass (active ingredient ratio) of the isocyanate-based cross-linking agent (i), heat-expandable particles (i) and zinc oxide are blended with 100 parts by mass of the active ingredient of the solution containing the acrylic copolymer (P1). Then, it was diluted with toluene and stirred uniformly to prepare a composition (ax) for a heat-expandable pressure-sensitive adhesive layer having an active ingredient concentration of 25% by mass.
The blending amount of the heat-expandable particles (i) and zinc oxide was 20% by mass of the heat-expandable particles (i) in the total amount (100% by mass of the active ingredient) of the composition (ax) for the heat-expandable pressure-sensitive adhesive layer. It was blended so that zinc oxide was 8% by mass.
Then, a PET film (manufactured by Toyobo Co., Ltd., product name "Cosmo Shine A4300", thickness: 50 μm) is used as the support (Y), and a prepared heat-expandable pressure-sensitive adhesive layer is used on one side of the PET film. The composition (ax) was applied to form a coating film. The coating film was dried at 70 ° C. for 5 minutes to form a heat-expandable pressure-sensitive adhesive layer (AX) having a thickness of 60 μm on the support (Y).
Then, the exposed surface of the heat-expandable pressure-sensitive adhesive layer (AX) and the surface of the release agent layer of the heavy-release film are bonded together to form the heavy-release film, the heat-expandable pressure-sensitive adhesive layer (AX), and the support (Y). ) And were laminated in this order to prepare a laminated body.

Production Example 2 (Formation of non-thermally expandable pressure-sensitive adhesive layer (X1))
In addition to 100 parts by mass of the active ingredient of the solution containing the acrylic copolymer (P2), 12 parts by mass (active ingredient ratio) of the energy ray-curable compound (i) and 1.1 parts by mass of the isocyanate-based cross-linking agent (i) ( Active ingredient ratio), photopolymerization initiator (i) 1 part by mass (active ingredient ratio), diluted with toluene, stirred uniformly, and pressure-sensitive adhesive composition (x-1) having an active ingredient concentration of 30% by mass. ) Was prepared.
Then, the prepared pressure-sensitive adhesive composition (x-1) is applied onto the peeling surface of the light release film to form a coating film, and the coating film is dried at 100 ° C. for 1 minute to have a thickness of 20 μm. A heat-expandable pressure-sensitive adhesive layer (X1) was formed.

Production Example 3 (Formation of non-thermally expandable pressure-sensitive adhesive layer (X2))
0.74 parts by mass (active ingredient ratio) of the isocyanate-based cross-linking agent (ii) was added to 100 parts by mass of the active ingredient of the solution containing the acrylic copolymer (P1), diluted with toluene, and uniformly stirred. A pressure-sensitive adhesive composition (x-2) having an active ingredient concentration of 25% by mass was prepared.
Then, the prepared pressure-sensitive adhesive composition (x-2) is applied onto the surface of the release agent layer of the heavy-release film to form a coating film, and the coating film is dried at 100 ° C. for 1 minute to obtain a thickness. A 5 μm non-thermally expandable pressure-sensitive adhesive layer (X2) was formed.

Example 1 (Formation of Adhesive Sheet)
The surface of the pressure-sensitive adhesive layer of the non-thermally expandable pressure-sensitive adhesive layer (X1) formed in Production Example 2 and the surface of the support (Y) of the laminate formed in Production Example 1 are bonded together to have the following configuration. An adhesive sheet was prepared.
<Heavy release film> / <Heat-expandable pressure-sensitive adhesive layer (AX), thickness: 60 μm> / <support (Y), thickness: 50 μm> / <non-heat-expandable pressure-sensitive adhesive layer (X1), thickness : 20 μm> / <Light release film>

Examples 2 to 6 and Comparative Example 1
The types and blending amounts of the heat-expandable particles used in the composition (ax) for the heat-expandable pressure-sensitive adhesive layer forming the heat-expandable pressure-sensitive adhesive layer (AX), and the types and contents of the dielectric heat-generating filler are set, respectively. An adhesive sheet was produced in the same manner as in Example 1 except that the changes were made as shown in Table 1 below.

Example 7
(1) Preparation of Solventless Heat-Expandable Substrate Composition (ay') 2-Hydroxyethyl acrylate is added to the terminal isocyanate urethane prepolymer obtained by reacting an ester-type diol with isophorone diisocyanate (IPDI). The reaction gave a linear urethane prepolymer having ethylenically unsaturated groups at both ends, which is an oligomer having a mass average molecular weight (Mw) of 5,000.
Then, 40 parts by mass (active ingredient ratio) of the urethane prepolymer synthesized above, 40 parts by mass of isobornyl acrylate (IBXA) (active ingredient ratio), and phenylhydroxypropyl acrylate (HPPA) as energy ray-polymerizable monomers. 20 parts by mass (active ingredient ratio) is blended, and 2.0 parts by mass (active ingredient ratio) of the photopolymerization initiator (ii) is further added to the total amount (100 parts by mass) of the urethane prepolymer and the energy ray-polymerizable monomer. ) And 0.2 parts by mass (active component ratio) of the phthalocyanine-based polymer was blended as an additive to prepare an energy ray-curable resin composition.
Then, the thermosetting particles (i) and zinc oxide were blended with the energy ray-curable resin composition to prepare a solvent-free composition (ay').
The blending amount of the heat-expandable particles (i) and zinc oxide was 64% by mass of the energy ray-curable resin composition and 64% by mass of the heat-expandable particles (100% by mass of the active ingredient) of the composition (ay'). It was blended so that i) was 20% by mass and zinc oxide was 16% by mass.

(2) Formation of a base material laminate in which a heat-expandable base material layer (AY) and a support (Y) are laminated As a support (Y), a PET film (manufactured by Toyobo Co., Ltd., product name "Cosmo Shine A4300"" , Thickness: 50 μm), and the composition (ay') was applied to one side of the PET film to form a coating film.
Then, using an ultraviolet irradiation device (manufactured by Eye Graphics Co., Ltd., product name "ECS-401GX") and a high-pressure mercury lamp (manufactured by Eye Graphics Co., Ltd., product name "H04-L41"), an illuminance of 160 mW / cm ² The coating film was cured by irradiating with ultraviolet rays under the condition of a light amount of 500 mJ / cm ² , and a heat-expandable base material layer (AY) having a thickness of 100 μm was formed on a PET film as a support (Y). The above-mentioned illuminance and light amount at the time of ultraviolet irradiation are values measured using an illuminance / photometer (manufactured by EIT, product name "UV Power Pack II").

(3) Formation of Adhesive Sheet The adhesive surface of the non-thermally expandable pressure-sensitive adhesive layer (X2) formed in Production Example 3 and the surface of the heat-expandable base material layer (AY) of the base material laminate were bonded together. .. Next, the adhesive surface of the non-thermally expandable pressure-sensitive adhesive layer (X1) formed in Production Example 2 and the surface of the PET film which is the support (Y) of the base material laminate were bonded together.
As a result, an adhesive sheet having the following structure was produced.
<Heavy release film> / <Non-thermally expandable adhesive layer (X2), thickness: 5 μm> / <heat-expandable base material layer (AY), thickness: 100 μm> / <support (Y), thickness : 50 μm> / <Non-thermally expandable adhesive layer (X1), Thickness: 20 μm> / <Light release film>

[High frequency peelability evaluation]
(Adhesive strength of layer (AX) or layer (X2) before and after high frequency application)
In the same manner as in each Example and Comparative Example, the pressure-sensitive adhesive sheets for evaluation of adhesive strength were used in the same manner as in each Example and Comparative Example, except that the non-thermally expandable pressure-sensitive adhesive layer (X1) was not formed in the pressure-sensitive adhesive sheets produced in each Example and Comparative Example. An adhesive sheet was prepared.
The obtained pressure-sensitive adhesive sheets for evaluation of adhesive strength were cut into test pieces having a size of 250 mm in length (MD) and 25 mm in width (TD), respectively.
Here, MD in the MD direction is an abbreviation for Machine Direction, and the MD direction means a long direction at the time of molding the adhesive sheet. Further, TD in the TD direction is an abbreviation for Transverse Direction, and the TD direction means the width direction at the time of molding the adhesive sheet. Here, the "MD direction" in the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples refers to the above-mentioned compositions for forming the heat-expandable pressure-sensitive adhesive layer (AX) or the non-heat-expandable pressure-sensitive adhesive layer (X2). Refers to the direction in which
Then, the heavy release film of the test piece is removed, and the surface of the exposed layer (AX) (corresponding to Examples 1 to 6) or layer (X2) (corresponding to Example 7) is formed on an aluminum plate (Co., Ltd.). Made by Paltec, product name "A5052P", size: length 100 mm x width 25 mm x thickness 2 mm), affixed to the surface with a 2 kg rubber roller based on JIS Z0237: 2000, and immediately after that, at 23 ° C, 50%. It was allowed to stand for 20 minutes in an environment of RH (relative humidity).
After standing under the above conditions, the tensile speed is increased by the 180 ° peeling method based on JIS Z0237: 2000 using a tensile tester (manufactured by A & D Co., Ltd., product name "Tencilon (registered trademark)"). The layer (AX) or layer (X2) was peeled off from the aluminum plate at 300 mm / min, and the adhesive strength (N / 25 mm) of the layer (AX) or layer (X2) before high frequency application was measured.
The adhesive strength after applying the high frequency was measured as follows after preparing a test piece in the same manner as described above and allowing it to stand for 20 minutes in the environment of 23 ° C. and 50% RH (relative humidity). Immediately before the test piece is evaluated by the same peeling method as described above, the test piece is fixed between the electrodes of a high-frequency dielectric heating device (manufactured by Yamamoto Vinita Co., Ltd., product name "YRP-400T-RC"). In this state, a high frequency was applied for 30 seconds under the conditions of a frequency of 40 MHz and an output of 130 W. Then, the adhesive strength (N / 25 mm) of the layer (AX) or the layer (X2) after applying the high frequency was evaluated in the same manner as the above-mentioned peeling method.
In Comparative Example 1, since a high frequency could not be applied as described later, only the state before the high frequency was applied was evaluated.

Each of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples was evaluated using the above-mentioned evaluation method. The results are shown in Table 1 or Table 2 below.

From Tables 1 and 2, it was confirmed that the adhesive sheets of Examples 1 to 7 were excellent in peelability when a high frequency was applied.
Further, the pressure-sensitive adhesive sheet of Example 4 has a large content of a dielectric heating filler, and the appearance of the exposed surface when the heat-expandable pressure-sensitive adhesive layer (AX) is formed is the pressure-sensitive adhesive sheets of Examples 1 to 3 and 5 to 6. The unevenness was conspicuous compared to.
On the other hand, in the adhesive sheet of Comparative Example 1, when a high frequency was applied, sparks were generated due to zinc, so that the safety device of the high frequency dielectric heating device worked and the high frequency could not be applied. Further, since zinc is not a dielectric substance, it is considered that zinc does not generate heat like the dielectric heating filler used in the examples even if a high frequency can be applied.

The pressure-sensitive adhesive sheet, which is one aspect of the present invention, has sufficient adhesive strength when attached to the adherend, but can be easily peeled off from the adherend by applying a high frequency. As long as an adherend to which can be applied is used, it can be applied to all uses.
For example, it can be used as various temporary fixing sheets used in the manufacturing process of materials for electronic devices as described above.
In addition to electronic device applications, the adhesive sheet according to one aspect of the present invention can be used for various purposes such as the above-mentioned protective film applications such as window films, protective / design-imparting applications such as wallpaper and wrapping films, and returnable labels. Various uses such as label use and use for attaching temporary notices and the like can be mentioned.

10, 20, 30, 40, 50, 60, 70 Adhesive sheet AX Thermal expansion adhesive layer (AX)
AY Thermally expandable substrate layer (AY)
X1 Non-thermally expandable pressure-sensitive adhesive layer (X1) not adjacent to the heat-expandable layer (A)
X2 Non-thermally expandable pressure-sensitive adhesive layer (X2) adjacent to the heat-expandable layer (A)
Y support (Y)
1 Surface that exhibits high-frequency peelability

Claims (11)

A pressure-sensitive adhesive sheet containing a heat-expandable particle and a dielectric heating filler and having a heat-expandable layer (A) containing at least the heat-expandable particles.
An adhesive sheet in which the dielectric heating filler is at least one selected from the group consisting of metal oxides and semimetal carbonized metals. The pressure-sensitive adhesive sheet according to claim 1, wherein the dielectric heat-generating filler is at least one selected from the group consisting of zinc oxide, titanium oxide, barium titanate, and silicon carbide. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the layer (A) contains the dielectric heating filler. The pressure-sensitive adhesive sheet according to claim 3, wherein the content of the dielectric heating filler in the layer (A) is 1 to 30% by mass. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the content of the heat-expandable particles in the layer (A) is 1 to 40% by mass. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the layer (A) is a heat-expandable pressure-sensitive adhesive layer (AX). The invention according to any one of claims 1 to 5, wherein the layer (A) is a heat-expandable base material layer (AY) and has a non-heat-expandable pressure-sensitive adhesive layer (X2) adjacent to the layer (A). Adhesive sheet. The adhesive sheet according to any one of claims 1 to 7, which has a support (Y). The adhesive sheet according to claim 8, wherein the layer (A) and the support (Y) are directly laminated in this order. The pressure-sensitive adhesive sheet according to claim 8 or 9, which has a layer (A), a support (Y), and a non-thermally expandable pressure-sensitive adhesive layer (X1) that is not adjacent to the layer (A) in this order. The pressure-sensitive adhesive sheet according to any one of claims 1 to 10, wherein the thermal expansion start temperature of the heat-expandable particles is 50 to 240 ° C.

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