WO2018181769A1 - Adhesive sheet - Google Patents

Abstract

Provided is an adhesive sheet comprising a layered body in which an adhesive layer (X1) and a non-adhesive thermally expandable substrate (Y) are directly layered in this order. The layered body is formed by directly layering, in this order, a material for forming the adhesive layer (X1), namely, a coating film (x1') comprising a composition (x1), and a material for forming the thermally expandable substrate (Y), namely, a coating film (y') comprising a composition containing a resin and thermally expandable particles, then simultaneously irradiating the coating film (x1') and the coating film (y') with an energy beam. The adhesive sheet leaves little adhesive residue on the surface of an adherend after being heated and peeled off, has good interfacial adhesion between the substrate and the adhesive layer, and exhibits excellent adhesion during temporary fixing and excellent peelability when heated.

Description

Adhesive sheet

The present invention relates to an adhesive sheet.

The pressure-sensitive adhesive sheet may be used not only for semi-permanent fixing of members but also for temporary fixing for temporarily fixing building materials, interior materials, electronic parts and the like. Such a pressure-sensitive adhesive sheet for temporarily fixing is required to satisfy both adhesiveness at the time of use and peelability after use.
Conventionally, a heat-peelable pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer containing thermally expandable particles is provided on a base material is known as a pressure-sensitive adhesive sheet for temporary fixing that satisfies the above-described requirements. The heat-peelable pressure-sensitive adhesive sheet has a feature that the adhesive force is reduced by foaming or expanding the thermally expandable particles by heating, and can be easily peeled off from the adherend. For this reason, it is used as a temporary fixing means, a recycling label, etc. during the manufacturing process of the electronic component.

For example, Patent Document 1 discloses a heat-peelable pressure-sensitive adhesive sheet in which a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres is provided on at least one side of a substrate, and the thickness of the heat-expandable pressure-sensitive adhesive layer The center line average roughness of the surface of the thermally expandable adhesive layer before heating is set to 0.4 μm or less by adjusting the maximum particle size of the thermally expandable microspheres added to the adhesive layer. A heat-peelable pressure-sensitive adhesive sheet for temporary fixing at the time of cutting an electronic component is disclosed.
In recent years, as electronic components have been miniaturized, the adhesion area between the pressure-sensitive adhesive sheet and the adherend has been reduced, and there have been cases where adhesion defects such as chip skipping have occurred. The heat-peelable pressure-sensitive adhesive sheet described in Patent Document 1 can secure an effective contact area with the pressure-sensitive adhesive sheet by suppressing the surface roughness of the heat-expandable pressure-sensitive adhesive layer, and prevents the occurrence of adhesive defects such as chip jumping. There is a statement that it can be done.

Japanese Patent No. 3594853

The conventional heat-peelable pressure-sensitive adhesive sheet expands the pressure-sensitive adhesive layer containing the thermally expandable particles by foaming or expanding the thermally expandable particles by heating. Due to the expansion of the pressure-sensitive adhesive layer, the surface of the pressure-sensitive adhesive layer in contact with the adherend is deformed into an uneven shape, and the adhesion area between the pressure-sensitive adhesive layer and the adherend is reduced. As a result, the adhesive force by the pressure-sensitive adhesive layer is reduced, and the pressure-sensitive adhesive sheet can be easily peeled off from the adherend.
However, when the heat-expandable particles are foamed or expanded by heating, destruction inside the pressure-sensitive adhesive layer containing the heat-expandable particles, that is, cohesive failure of the pressure-sensitive adhesive layer is likely to occur. As a result, there is a concern that the adhesive remains on the adherend surface after heat peeling (so-called adhesive residue).
In addition, when the adhesion between the base material and the pressure-sensitive adhesive layer is poor, when the heat-expandable pressure-sensitive adhesive layer is expanded by heating, it may cause undesired peeling between the base material and the pressure-sensitive adhesive layer. There is also.

Furthermore, the heat-peelable pressure-sensitive adhesive sheet described in Patent Document 1 suppresses the surface roughness of the heat-expandable pressure-sensitive adhesive layer from the viewpoint of improving adhesiveness at the time of temporary fixing. It is designed to reduce the particle size of the thermally expandable microspheres to be added. However, if the particle size of the heat-expandable microspheres is too small, the surface roughness becomes small, resulting in poor interfacial adhesion and concern about adhesive residue on the adherend surface after heat peeling.

The present invention has been made in view of the above problems, and has little adhesive residue on the adherend surface after heat peeling, and has good interface adhesion between the substrate and the pressure-sensitive adhesive layer. It aims at providing the adhesive sheet which is excellent in the adhesiveness at the time of temporary fixing, and heat peelability.

The present inventors have found that the above problem can be solved by including a thermally expandable particle in a base material and forming a laminate including the base material and the pressure-sensitive adhesive layer by a specific method. The present invention has been completed.

That is, the present invention provides the following [1] to [9].
[1] A pressure-sensitive adhesive sheet having a laminate in which a pressure-sensitive adhesive layer (X1) and a non-adhesive thermally expandable substrate (Y) are directly laminated in this order,
The laminate is
A coating film (x1 ′) comprising a composition (x1) which is a forming material of the pressure-sensitive adhesive layer (X1);
A coating film (y ′) comprising a composition (y) containing a resin and thermally expandable particles, which is a forming material of the thermally expandable substrate (Y),
Are directly laminated in this order, and then the pressure-sensitive adhesive sheet is formed by simultaneously irradiating the coating film (x1 ′) and the coating film (y ′) with energy rays.
[2] The pressure-sensitive adhesive sheet according to the above [1], wherein the energy beam irradiation is ultraviolet irradiation.
[3] The pressure-sensitive adhesive sheet according to [1] or [2], wherein the thermally expandable substrate (Y) satisfies the following requirement (1).
Requirement (1): The storage elastic modulus E ′ (t) of the thermally expandable substrate (Y) at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 ⁷ Pa or less.
[4] The pressure-sensitive adhesive sheet according to any one of [1] to [3], wherein the thermally expandable substrate (Y) satisfies the following requirement (2).
Requirement (2): The storage elastic modulus E ′ (23) of the thermally expandable substrate (Y) at 23 ° C. is 1.0 × 10 ⁶ Pa or more.
[5] The pressure-sensitive adhesive sheet according to any one of the above [1] to [4], wherein the thickness of the thermally expandable substrate (Y) is 10 to 1000 μm.
[6] The pressure-sensitive adhesive sheet according to any one of the above [1] to [5], wherein the probe tack value on the surface of the thermally expandable substrate (Y) is less than 50 mN / 5 mmφ.
[7] The laminate further includes an adhesive layer (X2), and the adhesive layer (X1), the thermally expandable substrate (Y), and the adhesive layer (X2) are directly laminated in this order. The pressure-sensitive adhesive sheet according to any one of [1] to [6] above.
[8] The laminate is
A coating film (x1 ′) comprising a composition (x1) which is a forming material of the pressure-sensitive adhesive layer (X1);
A coating film (y ′) comprising a composition (y) containing a resin and thermally expandable particles, which is a forming material of the thermally expandable substrate (Y),
A coating film (x2 ′) comprising a composition (x2) which is a forming material of the pressure-sensitive adhesive layer (X2);
Are directly laminated in this order, and then the pressure-sensitive adhesive sheet according to the above [7], which is formed by simultaneously irradiating the coating films (x1 ′), (y ′) and (x2 ′) with energy rays.
[9] The pressure-sensitive adhesive sheet according to any one of [1] to [8], wherein the thermally expandable particles have an average particle diameter before expansion at 23 ° C. of 3 to 100 μm.

The pressure-sensitive adhesive sheet of the present invention has little adhesive residue on the adherend surface after heat peeling, has good interface adhesion between the base material and the pressure-sensitive adhesive layer, and is excellent in adhesion and heat peelability during temporary fixing. .

It is a cross-sectional schematic diagram of an adhesive sheet which shows an example of a structure of the adhesive sheet of this invention. It is a cross-sectional schematic diagram of a double-sided pressure-sensitive adhesive sheet showing an example of the configuration of the pressure-sensitive adhesive sheet of the present invention.

In the present invention, the “active ingredient” refers to a component excluding a diluent solvent among components contained in a target composition.
The mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, specifically a value measured based on the method described in the examples.

In the present invention, for example, “(meth) acrylic acid” indicates both “acrylic acid” and “methacrylic acid”, and the same applies to other similar terms.
Moreover, about the preferable numerical range (for example, range of content etc.), the lower limit value and upper limit value which were described in steps can be combined independently, respectively. For example, from the description “preferably 10 to 90, more preferably 30 to 60”, “preferable lower limit (10)” and “more preferable upper limit (60)” are combined to obtain “10 to 60”. You can also.

≪Adhesive sheet≫
The pressure-sensitive adhesive sheet of the present invention will be described.
The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having a laminate in which a pressure-sensitive adhesive layer (X1) and a non-adhesive thermally expandable substrate (Y) are directly laminated in this order. Here, the laminate is a coating material (x1 ′) made of the composition (x1) that is a forming material of the pressure-sensitive adhesive layer (X1), and a resin that is a forming material of the thermally expandable substrate (Y) and After directly laminating the coating film (y ′) composed of the composition (y) containing thermally expandable particles in this order, the coating film (x1 ′) and the coating film (y ′) are simultaneously irradiated with energy rays. It is formed.
Here, the aforementioned “direct lamination” refers to a configuration in which a layer and a layer are in direct contact with each other without any other layer between the two layers. That is, in the present invention, the pressure-sensitive adhesive layer (X1) and the thermally expandable base material (Y) are in direct contact with no other layer interposed therebetween.

When the pressure-sensitive adhesive sheet of the present invention is peeled off from the adherend, the heat-expandable particles in the heat-expandable substrate (Y) are expanded by heating, and irregularities are formed on the surface of the heat-expandable substrate (Y). At the same time, the pressure-sensitive adhesive layer (X1) laminated on the irregularities is also pushed up, and irregularities are also formed on the surface of the pressure-sensitive adhesive layer (X1). And by forming unevenness on the surface of the pressure-sensitive adhesive layer (X1), the contact area between the adherend and the surface of the pressure-sensitive adhesive layer (X1) is reduced, and the adherend and pressure-sensitive adhesive layer (X1). There is a space between the surface of As a result, the pressure-sensitive adhesive sheet can be easily peeled off with a slight force from the adherend adhered to the surface of the pressure-sensitive adhesive layer (X1).
In the pressure-sensitive adhesive sheet of the present invention, the heat-expandable particles are not included in the pressure-sensitive adhesive layer (X1) but in the heat-expandable base material (Y), thereby suppressing cohesive failure of the pressure-sensitive adhesive layer (X1) due to heating. can do. Thereby, the adhesive residue on the adherend surface after heat peeling can be reduced.
Moreover, in the adhesive sheet of this invention, since the laminated body is formed by the specific method as mentioned above, the interface adhesiveness of an adhesive layer (X1) and a thermally expansible base material (Y) is made high. Can do. Thereby, even if the thermally expansible particle | grains in a thermally expansible base material (Y) expand | swell and an unevenness | corrugation is formed in the surface of a thermally expansible base material (Y), an adhesive layer (X1) and thermal expansibility Undesirable peeling from the base material (Y) can be suppressed, and as described above, irregularities are also formed on the surface of the pressure-sensitive adhesive layer (X1).

FIG.1 and FIG.2 is a cross-sectional schematic diagram which shows an example of a structure of the adhesive sheet of this invention.
As a specific configuration of the pressure-sensitive adhesive sheet of one embodiment of the present invention, for example, as shown in FIG. 1A, a pressure-sensitive adhesive layer (X1) 12 and a thermally expandable substrate (Y) 11 are directly laminated in this order. The adhesive sheet 1a which has the laminated body 10 currently used is mentioned. Moreover, it is good also as a structure which has the peeling material 13 further on the surface of adhesive layer (X1) 12, like the adhesive sheet 1b shown in FIG.1 (b).

As a specific configuration of the pressure-sensitive adhesive sheet of another aspect of the present invention, as shown in FIG. 2A, a pressure-sensitive adhesive layer (X1) 121, a thermally expandable substrate (Y) 11, and a pressure-sensitive adhesive layer The double-sided pressure-sensitive adhesive sheet 2a having the laminate 10 in which (X2) 122 is directly laminated in this order is exemplified. Moreover, like the double-sided pressure-sensitive adhesive sheet 2b shown in FIG. 2 (b), a release material 131 is further provided on the surface of the pressure-sensitive adhesive layer (X1) 121, and further peeled on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X2) 122. It is good also as a structure which has the material 132. FIG.
In addition, in the double-sided pressure-sensitive adhesive sheet 2b shown in FIG. 2 (b), the peeling force when peeling the release material 131 from the pressure-sensitive adhesive layer (X1) 121 and the peeling time when peeling the peeling material 132 from the pressure-sensitive adhesive layer (X2) 122 are removed. When the force is approximately the same, when the two release materials are pulled outward to be peeled off, a phenomenon may occur in which the pressure-sensitive adhesive layer is divided and peeled off along with the two release materials.
From the viewpoint of suppressing such a phenomenon, it is preferable to use two types of release materials designed so that the two release materials 131 and 132 have different release forces from the adhesive layer attached to each other.

As another pressure-sensitive adhesive sheet, in the double-sided pressure-sensitive adhesive sheet 2a shown in FIG. 2 (a), one surface of the pressure-sensitive adhesive layer (X1) 121 and the pressure-sensitive adhesive layer (X2) 122 is peeled off on both surfaces. A double-sided pressure-sensitive adhesive sheet having a configuration in which materials are laminated in a roll shape may be used.

<Laminated body>
The laminate of the pressure-sensitive adhesive sheet of the present invention is a laminate in which the pressure-sensitive adhesive layer (X1) and the non-adhesive thermally expandable substrate (Y) are directly laminated in this order, and the pressure-sensitive adhesive layer (X1 ) And a coating composition (x1 ′) comprising the composition (x1) as a forming material, and a composition (y) comprising a resin and a thermally expandable particle as a forming material for the thermally expandable substrate (Y). The coating film (y ′) and the coating film (x ′ ′) and the coating film (y ′) are simultaneously irradiated with energy rays after being directly laminated in this order.
Examples of the energy ray irradiation include ultraviolet ray irradiation and electron beam irradiation, but ultraviolet ray irradiation is preferable from the viewpoint of preventing unnecessary reactions.
In the present invention, the coating film (x1 ′) and the coating film (y ′) are “simultaneously” formed into an energy ray-irradiated laminate, so that the coating film (x1 ′) and the coating film (y ′) are “separated”. Compared with the method of forming a laminate by irradiating energy rays, the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) can be enhanced.
A coating film (x1 ′) made of the composition (x1) which is a forming material of the pressure-sensitive adhesive layer (X1) and a coating film (y) which is a forming material of the thermally expandable substrate (Y) (y) In the process of simultaneously irradiating the energy beam with '), a mixed layer of the coating film is formed in the vicinity of the interface, and the molecular chains of the resins contained in each composition are intertwined, so that the pressure-sensitive adhesive layer (X1) and the thermally expandable group It is considered that the interfacial adhesion with the material (Y) is improved.

As an example of a method of forming a laminate by irradiating the coating film (x1 ′) and the coating film (y ′) with energy rays “separately”, the following method may be mentioned.
The composition (x1) is applied onto the release-treated surface of a release material such as a release film to form a coating film (x1 ′), and the coating film (x1 ′) is irradiated with energy rays to form an adhesive layer (X1). Form. In addition, a coating (y ′) is formed by applying a composition (y) containing a resin and thermally expandable particles on a release-treated surface of a release material such as a release film prepared separately. ') Is irradiated with energy rays to form a thermally expandable substrate (Y). Then, the surface which is not in contact with the release material of the pressure-sensitive adhesive layer (X1) and the surface which is not in contact with the release material of the thermally expandable base material (Y) are bonded together to form a laminate.

In the method of forming a laminate by irradiating the coating film (x1 ′) and the coating film (y ′) “separately” with energy rays as described above, the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y ) Are formed separately, the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) is low.

The laminate of the pressure-sensitive adhesive sheet of one embodiment of the present invention is preferably a composition (x1) that is a material for forming the pressure-sensitive adhesive layer (X1) and a material that is a material for forming the thermally expandable substrate (Y). (Y) is applied simultaneously, and the coating film (x1 ′) and the coating film (y ′) are directly laminated in this order, and then the coating film (x1 ′) and the coating film (y ′) are simultaneously energized. It is formed by irradiation. By simultaneously applying the composition (x1) and the composition (y), the entanglement of the molecular chains of the resins contained in each composition is promoted compared to the case where each composition is sequentially applied. Interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) can be further increased.

The laminate of the pressure-sensitive adhesive sheet of one embodiment of the present invention further includes a pressure-sensitive adhesive layer (X2), and the pressure-sensitive adhesive layer (X1), the thermally expandable substrate (Y), and the pressure-sensitive adhesive layer (X2) are in this order. It is good also as a structure laminated | stacked directly by. The pressure-sensitive adhesive layer (X2) is a layer formed from the composition (x2).
As a method of forming a laminate further including the above-mentioned pressure-sensitive adhesive layer (X2), for example, the composition (x2) is applied on the expandable substrate (Y) to form a coating film (x2 ′), A method of forming the coating film (x2 ′) by irradiating with energy rays can be mentioned. Moreover, for example, the pressure-sensitive adhesive layer (X2) prepared in advance by irradiating the coating film (x2 ′) with energy rays may be directly attached on the expandable substrate (Y).

The laminate further including the above-mentioned pressure-sensitive adhesive layer (X2) is preferably a coating film (x1 ′) composed of the composition (x1) which is a forming material of the pressure-sensitive adhesive layer (X1), and a thermally expandable substrate ( A coating material (y ′) composed of a composition (y) containing a resin and thermally expandable particles, which is a forming material of Y), and a coating composition (x2), which is a forming material of an adhesive layer (X2). After the film (x2 ′) is directly laminated in this order, the coating films (x1 ′), (y ′) and (x2 ′) are simultaneously irradiated with energy rays.
By forming the laminate further including the pressure-sensitive adhesive layer (X2) in this manner, the interfacial adhesion between the thermally expandable base material (Y) and the pressure-sensitive adhesive layer (X2) can also be improved for the reason described above. .

The laminate further including the pressure-sensitive adhesive layer (X2) is more preferably a composition (x1) which is a material for forming the pressure-sensitive adhesive layer (X1) and a material for forming the heat-expandable base material (Y). The composition (y) and the composition (x2), which is a material for forming the pressure-sensitive adhesive layer (X2), are applied simultaneously, and the coating films (x1 ′), (y ′), and (x2 ′) are applied in this order. After the direct lamination, the coating films (x1 ′), (y ′) and (x2 ′) are simultaneously irradiated with energy rays.
By forming the laminated body further including the pressure-sensitive adhesive layer (X2) in this manner, the interfacial adhesion between the thermally expandable base material (Y) and the pressure-sensitive adhesive layer (X2) can be further improved for the reason described above. it can.

In addition, in this invention, although the laminated body which an adhesive sheet has is specified by the manufacturing method as mentioned above, the situation which must specify by such a manufacturing method exists.
Regarding the interface between the pressure-sensitive adhesive layer (X1) and the heat-expandable substrate (Y), as an evaluation based on objective physical property values, for example, the pressure-sensitive adhesive layer (X1) and heat in a cross section cut in the thickness direction of the laminate A method for measuring the roughness of the interface by observing the interface with the expandable substrate (Y) using an electron microscope or the like can be considered. However, since the roughness of the interface is very small, it cannot be measured accurately, and the difference in the roughness state depending on the region to be observed is very large. Therefore, it is extremely difficult to evaluate with specific physical property values such as interface roughness.
Further, depending on the type of the adhesive resin contained in the adhesive layer (X1) and the resin contained in the thermally expandable substrate (Y), the adhesive layer (X1) and the thermally expandable material can be obtained using an electron microscope or the like. Even if it is attempted to observe the interface with the substrate (Y), the interface may become unclear, and the roughness measurement itself may be difficult in the first place.
Furthermore, when the laminate is cut in the thickness direction in order to obtain a cross section of the laminate, the laminate is formed of a resin, and thus the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate There is also a situation that the shape of the interface with (Y) collapses and the state of the interface cannot be accurately evaluated.
From such circumstances, in the present invention, the laminate that the pressure-sensitive adhesive sheet has is specified by the manufacturing method as described above.
In addition, a laminated body is the structure by which the adhesive layer (X1), the thermally expansible base material (Y), and the adhesive layer (X2) are directly laminated | stacked in this order, Comprising: With coating film (x1 ') A case where (y ′) and (x2 ′) are directly laminated in this order and then the coating films (x1 ′), (y ′) and (x2 ′) are simultaneously irradiated with energy rays. There are the same circumstances as described above for the interface between the pressure-sensitive adhesive layer (X1) and the heat-expandable base material (Y) and the interface between the heat-expandable base material (Y) and the pressure-sensitive adhesive layer (X2). It must be specified by such a manufacturing method.

In addition, about the method of forming a coating film (x1 '), (y') and (x2 '), and the energy ray irradiation conditions of the formed coating film, respectively, to the item of "the manufacturing method of an adhesive sheet" mentioned later, respectively. As described.

The thickness of the laminate of the pressure-sensitive adhesive sheet of the present invention is preferably 10 to 1200 μm, more preferably 25 to 500 μm, still more preferably 40 to 300 μm, and still more preferably 55 to 200 μm.

The thickness of the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet of the present invention is based on the viewpoint of developing an excellent pressure-sensitive adhesive force, and the expansion of the heat-expandable particles in the heat-expandable substrate (Y) by heat treatment. From the viewpoint of easily forming irregularities on the surface of the pressure-sensitive adhesive layer (X1), the thickness is preferably 1 to 100 μm, more preferably 2 to 70 μm, still more preferably 3 to 40 μm, and still more preferably 5 to 30 μm.

The thickness of the thermally expandable substrate (Y) of the pressure-sensitive adhesive sheet of the present invention is preferably 10 to 1000 μm, more preferably 20 to 500 μm, still more preferably 25 to 400 μm, and still more preferably 30 to 300 μm.

When the laminated body which the adhesive sheet of 1 aspect of this invention further contains an adhesive layer (X2), the viewpoint which expresses the outstanding adhesive force, and the thermal expansion in the thermally expansible base material (Y) by heat processing From the viewpoint of easily forming irregularities on the surface of the pressure-sensitive adhesive layer (X2) due to the expansion of the adhesive particles, it is preferably 1 to 100 μm, more preferably 2 to 70 μm, still more preferably 3 to 40 μm, still more preferably 5 to 30 μm.

In the present specification, the thickness of the laminate is a value measured using a constant pressure thickness measuring instrument based on JIS K6783, Z1702, and Z1709, and specifically measured based on the method described in the examples. Means the value.
The thickness of each layer constituting the laminate may be measured by the same method as the thickness of the laminate described above. For example, a cross section of the laminate cut in the thickness direction is observed with a scanning electron microscope. Then, the ratio of the thickness of each layer may be measured and calculated from the thickness of the laminate measured by the method described above.

In the laminate of the pressure-sensitive adhesive sheet of the present invention, the ratio of the thickness of the heat-expandable base material (Y) and the thickness of the pressure-sensitive adhesive layer (X1) at 23 ° C. (heat-expandable base material (Y) / pressure-sensitive adhesive layer) (X1)) is preferably 0.2 or more, more preferably 0.5 or more, still more preferably 1.0 or more, and still more preferably 5.0 or more, from the viewpoint of preventing positional displacement of the object. In addition, from the viewpoint of forming a pressure-sensitive adhesive sheet that can be easily peeled with a slight force when peeled, it is preferably 1000 or less, more preferably 200 or less, still more preferably 60 or less, and even more preferably 30 or less. .
When the laminated body which the adhesive sheet of 1 aspect of this invention further contains an adhesive layer (X2), the ratio of the thickness of a thermally expansible base material (Y) and the thickness of an adhesive layer (X2) in 23 degreeC From the same viewpoint, the (thermally expandable substrate (Y) / adhesive layer (X2)) is preferably 0.2 or more, more preferably 0.5 or more, still more preferably 1.0 or more, and still more. Preferably, it is 5.0 or more, preferably 1000 or less, more preferably 200 or less, still more preferably 60 or less, and still more preferably 30 or less.

In addition, as for the said laminated body which the adhesive sheet of this invention has as above-mentioned, a mixed layer arises between two coating films in the energy ray irradiation process of a coating film, and an adhesive layer (X1) and a thermally expansible base material (Y ) And the interface between the thermally expandable base material (Y) and the pressure-sensitive adhesive layer (X2) may be unclear enough to disappear.
When a mixed layer is formed between the two coating films and between the formed layers, for example, as described above, the cross section of the laminate cut in the thickness direction is observed with a scanning electron microscope to determine the thickness of each layer. When the thickness ratio is measured and a mixed layer is formed between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y), the intermediate point in the thickness direction of the mixed layer The thickness ratio of each layer may be measured on the assumption that an interface exists on a plane parallel to the surface of the pressure-sensitive adhesive layer (X1) opposite to the thermally expandable substrate (Y). .

[Thermo-expandable substrate (Y)]
The heat-expandable substrate (Y) of the pressure-sensitive adhesive sheet of the present invention is a layer formed by irradiating a coating film (y ′) made of a composition (y) containing a resin and heat-expandable particles by energy rays. A non-adhesive substrate.
In the present invention, whether or not the non-adhesive substrate is determined if the probe tack value measured in accordance with JIS Z0237: 1991 is less than 50 mN / 5 mmφ with respect to the surface of the target substrate. The said base material is judged as a "non-adhesive base material".
Here, the probe tack value on the surface of the thermally expandable substrate (Y) is usually less than 50 mN / 5 mmφ, preferably less than 30 mN / 5 mmφ, more preferably less than 10 mN / 5 mmφ, and even more preferably 5 mN / 5 mmφ. Is less than.
In addition, the specific measuring method of the probe tack value in the surface of a thermally expansible base material (Y) is based on the method as described in an Example.

The heat-expandable substrate (Y) that the pressure-sensitive adhesive sheet of the present invention has is preferably a non-adhesive substrate that satisfies the following requirement (1).
Requirement (1): The storage elastic modulus E ′ (t) of the thermally expandable substrate (Y) at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 ⁷ Pa or less.
In the present specification, the storage elastic modulus E ′ of the thermally expandable substrate (Y) at a predetermined temperature means a value measured by the method described in the examples.
The said requirement (1) prescribes | regulates the storage elastic modulus E 'of a thermally expansible base material (Y) at the time of peeling of an adhesive sheet.
When the pressure-sensitive adhesive sheet of the present invention is peeled from the adherend, the heat-expandable particles in the heat-expandable substrate (Y) are heated to a temperature equal to or higher than the expansion start temperature (t) of the heat-expandable particles. Expands and irregularities are formed on the surface of the heat-expandable substrate (Y), and the pressure-sensitive adhesive layer (X1) laminated on the irregularities is also pushed up to form irregularities on the adhesive surface.
And by forming unevenness on the adhesive surface of the pressure-sensitive adhesive layer (X1), the contact area between the adherend and the adhesive surface is reduced, and a space is created between the adherend and the adhesive surface. The pressure-sensitive adhesive sheet can be easily peeled off from the adherend with a slight force.

Incidentally, in order to improve the peelability of the pressure-sensitive adhesive sheet, it is necessary to make it easy to form irregularities on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X1) when heated to a temperature equal to or higher than the expansion start temperature (t). For that purpose, it is necessary that the heat-expandable particles contained in the heat-expandable base material (Y) are adjusted so as to easily expand.

In the above requirement (1), the storage elastic modulus E ′ (t) of the thermally expandable substrate at the expansion start temperature (t) of the thermally expandable particles is defined. It can also be said that the index indicates the rigidity of the thermally expandable substrate immediately before expansion.
That is, according to the study by the present inventors, the storage elastic modulus E ′ (t) of the thermally expandable substrate (Y) at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 ⁷ Pa. With the following, when heating to a temperature equal to or higher than the expansion start temperature (t) and trying to expand the thermally expandable particles, the expansion is not suppressed and the surface of the thermally expandable substrate (Y) is not suppressed. The unevenness | corrugation of the adhesion surface of the adhesive layer (X1) laminated | stacked can fully be formed.

From the above viewpoint, the storage elastic modulus E ′ (t) defined by the requirement (1) of the thermally expandable substrate (Y) used in one embodiment of the present invention is preferably 9.0 × 10 ⁶ Pa or less, more preferably. Is 8.0 × 10 ⁶ Pa or less, more preferably 6.0 × 10 ⁶ Pa or less, and still more preferably 4.0 × 10 ⁶ Pa or less.
Further, from the viewpoint of suppressing the flow of the expanded thermally expandable particles, improving the shape maintaining property of the unevenness formed on the adhesive surface of the pressure-sensitive adhesive layer (X1), and further improving the peelability, the thermally expandable group. The storage elastic modulus E ′ (t) defined by the requirement (1) of the material (Y) is preferably 1.0 × 10 ³ Pa or more, more preferably 1.0 × 10 ⁴ Pa or more, and still more preferably 1. 0 × 10 ⁵ Pa or more.

Moreover, it is preferable that the thermally expansible base material (Y) which the adhesive sheet of 1 aspect of this invention has further satisfy | fills the following requirements (2).
Requirement (2): The storage elastic modulus E ′ (23) of the thermally expandable substrate (Y) at 23 ° C. is 1.0 × 10 ⁶ Pa or more.

By using the heat-expandable base material (Y) that satisfies the above requirement (2), it is possible to prevent positional deviation when attaching an object such as a semiconductor chip. Moreover, when a target object is stuck, excessive sinking into the pressure-sensitive adhesive layer can also be prevented.

From the above viewpoint, the storage elastic modulus E ′ (23) of the thermally expandable substrate (Y) defined by the requirement (2) is preferably 5.0 × 10 ⁶ to 5.0 × 10 ¹² Pa, more preferably Is 1.0 × 10 ⁷ to 1.0 × 10 ¹² Pa, more preferably 5.0 × 10 ⁷ to 1.0 × 10 ¹¹ Pa, and still more preferably 1.0 × 10 ⁸ to 1.0 × 10 10. ¹⁰ Pa.

The composition (y), which is a material for forming the thermally expandable substrate (Y), contains a resin and thermally expandable particles. In addition, in 1 aspect of this invention, you may contain the additive for base materials contained in the base material which a general adhesive sheet has as long as the effect of this invention is not impaired.

(Thermally expandable particles)
As the heat-expandable particles used in the present invention, known heat-expandable particles can be used, and are appropriately selected according to the use of the pressure-sensitive adhesive sheet.
The thermally expandable particle is a microencapsulated foaming agent composed of an outer shell made of a thermoplastic resin and an encapsulated component encapsulated in the outer shell and vaporized when heated to a predetermined temperature. It is preferable.
Examples of the thermoplastic resin constituting the outer shell of the microencapsulated foaming agent include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, and polysulfone.

Examples of the inclusion component contained in the outer shell include propane, butane, pentane, hexane, heptane, octane, nonane, decane, isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, cyclopropane, cyclobutane, cyclopentane. , Cyclohexane, cycloheptane, cyclooctane, neopentane, dodecane, isododecane, cyclotridecane, hexylcyclohexane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nanodecane, isotridecane, 4-methyldodecane, isotetradecane, isopentadecane, iso Hexadecane, 2,2,4,4,6,8,8-heptamethylnonane, isoheptadecane, isooctadecane, isonanodecane, , 6,10,14-tetramethylpentadecane, cyclotridecane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, octadecylcyclohexane, etc. .
These encapsulated components may be used alone or in combination of two or more.

The average particle diameter of the thermally expandable particles before expansion at 23 ° C. used in one embodiment of the present invention is preferably 3 to 100 μm, more preferably 4 to 70 μm, still more preferably 6 to 60 μm, still more preferably 10 to 50 μm.
The average particle diameter before expansion of the thermally expandable particles is the volume-median particle diameter (D ₅₀ ), and is a laser diffraction particle size distribution measuring device (for example, product name “Mastersizer 3000” manufactured by Malvern). In the particle distribution of the heat-expandable particles before expansion measured by means of a particle diameter, the cumulative volume frequency calculated from the smaller particle diameter of the heat-expandable particles before expansion means a particle diameter corresponding to 50%.

The 90% particle diameter (D ₉₀ ) before expansion at 23 ° C. of the thermally expandable particles used in one embodiment of the present invention is preferably 10 to 150 μm, more preferably 20 to 100 μm, still more preferably 25 to 90 μm, More preferably, it is 30 to 80 μm.
The 90% particle diameter (D ₉₀ ) before expansion of the thermally expandable particles is the expansion measured by using a laser diffraction particle size distribution measuring apparatus (for example, product name “Mastersizer 3000” manufactured by Malvern). In the particle distribution of the previous thermally expandable particles, it means a particle diameter corresponding to 90% of the cumulative volume frequency calculated from the smaller particle diameter of the thermally expandable particles before expansion.

The thermally expandable particles used in the present invention are preferably particles having an expansion start temperature (t) adjusted to 120 to 250 ° C. The expansion start temperature (t) of the thermally expandable particles can be adjusted by appropriately selecting the type of inclusion component.
In the present specification, the expansion start temperature (t) of the thermally expandable particles means a value measured based on the following method.
[Measurement 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 thermally expandable particles to be measured is added, and an aluminum lid (diameter 5.6 mm, thickness 0. 1 mm) is prepared.
Using a dynamic viscoelasticity measuring device, the height of the sample is measured from the upper part of the aluminum lid while a force of 0.01 N is applied to the sample by a pressurizer. Then, in a state where a force of 0.01 N is applied by the pressurizer, heating is performed from 20 ° C. to 300 ° C. at a rate of temperature increase of 10 ° C./min, and the amount of displacement of the pressurizer in the vertical direction is measured. Let the displacement start temperature be the expansion start temperature (t).

The volume expansion coefficient of the thermally expandable particles used in one embodiment of the present invention by heating at an expansion start temperature (t) or higher is preferably 1.5 to 100 times, more preferably 2 to 80 times, and still more preferably 2. It is 5 to 60 times, more preferably 3 to 40 times.

The content of the heat-expandable particles is preferably 1 to 40% by mass, more preferably 5 to 35% by mass, still more preferably 10 to 10% by mass with respect to the total amount (100% by mass) of the active ingredients in the composition (y). 30% by mass, and still more preferably 15 to 25% by mass.

(resin)
The resin contained in the composition (y) may be a polymer that can form a non-adhesive thermally expandable substrate (Y).
In addition, as resin contained in a composition (y), non-adhesive resin may be sufficient and adhesive resin may be sufficient.
That is, even if the resin contained in the composition (y) is an adhesive resin, the adhesive resin is polymerized with the polymerizable compound in the process of forming the thermally expandable substrate (Y) from the composition (y). It is sufficient that the resin obtained by the reaction becomes a non-adhesive resin and the thermally expandable substrate (Y) containing the resin becomes non-adhesive.

(Solvent-free resin composition (y1))
As the composition (y) used in one embodiment of the present invention, an oligomer having an ethylenically unsaturated group having a mass average molecular weight (Mw) of 50000 or less, an energy ray polymerizable monomer, and the above-described thermally expandable particles are blended. And a solventless resin composition (y1) containing no solvent.
In the solventless resin composition (y1), no solvent is blended, but the energy beam polymerizable monomer contributes to the improvement of the plasticity of the oligomer.

In addition, about the kind and shape of thermally expansible particle | grains mix | blended with a solventless type resin composition (y1), and compounding quantity (content), it is as above-mentioned.
The mass average molecular weight (Mw) of the oligomer contained in the solventless resin composition (y1) is 50000 or less, preferably 1000 to 50000, more preferably 2000 to 40000, and still more preferably 3000 to 35000. More preferably, it is 4000-30000.
The oligomer may be any oligomer having an ethylenically unsaturated group having a mass average molecular weight of 50000 or less, but a urethane prepolymer (UP) described later is preferable.
As the oligomer, a modified olefin resin having an ethylenically unsaturated group can also be used.

Urethane prepolymer (UP) includes a reaction product of a polyol and a polyvalent isocyanate.

Examples of the polyol used as a raw material for the urethane prepolymer (UP) include alkylene type polyols, ether type polyols, ester type polyols, ester amide type polyols, ester / ether type polyols, and carbonate type polyols.
These polyols may be used independently and may use 2 or more types together.
The polyol used in one embodiment of the present invention is preferably a diol, more preferably an ester diol, an alkylene diol, and a carbonate diol, and even more preferably an ester diol and a carbonate diol.

Examples of ester type diols include alkane diols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol; ethylene glycol, propylene glycol, One or more selected from diols such as alkylene glycols such as diethylene glycol and dipropylene glycol; 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, het acid, maleic acid, fumaric acid, itaconic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, hexa Hydrophthalic acid, Examples thereof include condensation polymers of one or more selected from dicarboxylic acids such as hexahydroisophthalic acid, hexahydroterephthalic acid, and methylhexahydrophthalic acid, and anhydrides thereof.
Specifically, polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene 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 and polyneo Examples thereof include pentyl terephthalate diol.

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

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 polyvalent isocyanate used as a raw material for the urethane prepolymer (UP) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.
These polyvalent isocyanates may be used alone or in combination of two or more.
These polyisocyanates may be a trimethylolpropane adduct type modified product, a burette type modified product reacted with water, or an isocyanurate type modified product containing an isocyanurate ring.

Among these, the polyisocyanate used in one embodiment of the present invention is preferably diisocyanate, and 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2,6 More preferred is at least one selected from tolylene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), and alicyclic diisocyanate.

Examples of the alicyclic diisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate, IPDI), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane. Examples include diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, and isophorone diisocyanate (IPDI) is preferred.

In one embodiment of the present invention, the urethane prepolymer (UP) is preferably a linear urethane prepolymer that is a reaction product of a diol and a diisocyanate and has ethylenically unsaturated groups at both ends.
As a method for introducing an ethylenically unsaturated group into both ends of a linear urethane prepolymer, an NCO group at the end of a linear urethane prepolymer obtained by reacting a diol and a diisocyanate compound, a hydroxyalkyl (meth) acrylate, The method of making this react is mentioned.

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.

(Modified olefin resin having an ethylenically unsaturated group)
The modified olefinic resin having an ethylenically unsaturated group is obtained by introducing an ethylenically unsaturated group into 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 specifically includes ethylene, propylene, butylene, isobutylene, 1-hexene and the like.
Among these, ethylene and propylene are preferable.

Examples of the modified olefin resin having an ethylenically unsaturated group include an acrylic modified olefin resin obtained by subjecting an olefin resin to acrylic modification.
An acrylic modified olefin resin obtained by subjecting an olefin resin to acrylic modification is a modified polymer obtained by graft-polymerizing an alkyl (meth) acrylate as a side chain to an unmodified olefin resin as a main chain. Is mentioned.
Specific unmodified olefin resin, 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 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), polyethylene resin such as linear low density polyethylene Polypropylene resin (PP); Polybutene resin (PB); Ethylene-propylene copolymer; Olefin elastomer (TPO); Poly (4-methyl-1-pentene) (PMP); Ethylene-vinyl acetate copolymer (EVA) ); Ethylene-vinyl alcohol copolymer (EVOH); And olefinic terpolymers such as lopyrene- (5-ethylidene-2-norbornene); and the like.
The number of carbon atoms in the alkyl group of the alkyl (meth) acrylate is preferably 1-20, more preferably 1-16, and still more preferably 1-12.
Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, Examples include tridecyl (meth) acrylate and stearyl (meth) acrylate.

The total content of the oligomer and the energy beam polymerizable monomer in the solventless resin composition (y1) is preferably 50 to 100% with respect to the total amount (100% by mass) of the solventless resin composition (y1). It is 99% by mass, more preferably 60 to 95% by mass, still more preferably 65 to 90% by mass, and still more preferably 70 to 85% by mass.

Examples of the energy ray polymerizable monomer include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, adamantane ( Cycloaliphatic polymerizable compounds such as (meth) acrylate and tricyclodecane acrylate; Aromatic polymerizable compounds such as phenylhydroxypropyl acrylate, benzyl acrylate and phenol ethylene oxide modified acrylate; Tetrahydrofurfuryl (meth) acrylate, morpholine acrylate, N- And heterocyclic polymerizable compounds such as vinylpyrrolidone and N-vinylcaprolactam.
These energy beam polymerizable monomers may be used independently and may use 2 or more types together.

In the solvent-free resin composition (y1), the content ratio of the oligomer to the energy beam polymerizable monomer [oligomer / energy beam polymerizable monomer) is preferably 20/80 to 90 / in mass ratio. 10, more preferably 30/70 to 85/15, still more preferably 35/65 to 80/20.

In one embodiment of the present invention, the solventless resin composition (y1) preferably further contains a photopolymerization initiator.
By containing the photopolymerization initiator, the curing reaction can be sufficiently advanced even by irradiation with a relatively low energy beam.

Examples of the photopolymerization initiator include 1-hydroxy-cyclohexyl-phenyl-ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyrol. Nitrile, dibenzyl, diacetyl, 8-chloroanthraquinone and the like can be mentioned.
These photoinitiators may be used independently and may use 2 or more types together.

The blending amount of the photopolymerization initiator is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 4 parts by mass with respect to the total amount (100 parts by mass) of the oligomer and the energy ray polymerizable monomer. The amount is preferably 0.02 to 3 parts by mass.

(Substrate additive)
The composition (y) used in one embodiment of the present invention may contain a base material additive contained in a base material included in a general pressure-sensitive adhesive sheet as long as the effects of the present invention are not impaired.
Examples of such base material additives include ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, antiblocking agents, and colorants.
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 with respect to 100 parts by mass of the total amount of the resin contained in the composition (y). Part by mass, more preferably 0.001 to 10 parts by mass.
In one embodiment of the present invention, the composition (y) may contain a diluting solvent such as water or an organic solvent together with the above-mentioned various active ingredients as long as it is in a trace amount, but it is preferably not contained.

[Adhesive layer (X1)]
The pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet of the present invention is a layer formed by irradiating a coating film (x1 ′) comprising the composition (x1) with energy rays, and has adhesiveness.
In one embodiment of the present invention, the adhesive force on the adhesive surface of the adhesive layer (X1) at 23 ° C. before expansion of the thermally expandable particles is preferably 0.1 to 10.0 N / 25 mm, more preferably 0. The range is from 0.2 to 8.0 N / 25 mm, more preferably from 0.4 to 6.0 N / 25 mm, still more preferably from 0.5 to 4.0 N / 25 mm.
When the adhesive force is 0.1 N / 25 mm or more, the adherend of the semiconductor chip or the like can be sufficiently fixed to the extent that positional displacement can be prevented in the next step such as the sealing step.
On the other hand, if the said adhesive force is 10.0 N / 25mm or less, it can peel easily by slight force by heating to the expansion start temperature (t) at the time of peeling.
In addition, said adhesive force means the value measured by the method as described in an Example.

(Composition (x1))
The composition (x1) should just be a composition which can form an adhesive layer (X1) by energy ray irradiation. That is, the resin obtained by irradiating the composition (x1) with energy rays may be an adhesive resin.
That is, the component itself contained in the composition (x1) may be non-adhesive or adhesive. Even if the component contained in the composition (x1) is non-adhesive, the resin obtained in the process of forming the adhesive layer (X1) from the composition (x1) may be an adhesive resin.

As the adhesive resin obtained from the composition (x1), a resin having adhesiveness is preferable.
Specific examples of the adhesive resin include rubber resins such as acrylic resins, urethane resins, acrylic urethane resins, and polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins. Etc.
These adhesive resins may be used independently and may use 2 or more types together.
In addition, when these adhesive resins are copolymers having two or more kinds of structural units, the form of the copolymer is not particularly limited, and a block copolymer, a random copolymer, and a graft copolymer are not limited. Any of polymers may be used.

In one embodiment of the present invention, the surface of the pressure-sensitive adhesive layer (X1) is uneven due to the viewpoint of developing excellent adhesive force and the expansion of the thermally expandable particles in the thermally expandable substrate (Y) by heat treatment. From the viewpoint of facilitating formation, the adhesive resin preferably contains an acrylic urethane-based resin.
The content of the acrylic urethane-based resin in the adhesive resin is preferably 30 to 100% by mass, more preferably 50%, based on the total amount (100% by mass) of the adhesive resin contained in the adhesive layer (X1). To 100% by mass, more preferably 70 to 100% by mass, and still more preferably 85 to 100% by mass. Hereinafter, the composition (x1) for obtaining the acrylic urethane resin will be described.

The acrylic urethane-based resin can be produced by irradiating the composition (x1) containing the following (1) polymerization component with energy rays. The composition (x1) may contain (2) a polymerization initiator and (3) various additives as necessary.
(1) Polymerization component The composition (x1) is at least one polymerization component selected from the group consisting of a polymerizable vinyl monomer, a polymerizable vinyl prepolymer, a polyfunctional (meth) acrylate monomer, and a polyfunctional (meth) acrylate oligomer. Containing.

The composition (x1) preferably contains at least a polymerizable vinyl monomer and a polyfunctional (meth) acrylate oligomer among the above-described four kinds of polymerization components. When the polymerization component contains these compounds, the cohesive force of the obtained pressure-sensitive adhesive is improved, and adhesive residue on the adherend can be suppressed.

(1-1) Polymerizable vinyl monomer The polymerizable vinyl monomer is not particularly limited as long as it has a vinyl group-containing group, and conventionally known monomers can be appropriately used. In addition, the polymerizable vinyl monomer in this embodiment means the polymerizable vinyl monomer which has one vinyl group containing group, and does not overlap with the polyfunctional (meth) acrylate monomer mentioned later.

Specific examples of the polymerizable vinyl monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, and cyclohexyl (meth). Acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) In the molecule such as acrylate, isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, polyoxyalkylene modified (meth) acrylate No functional groups other than alkenyl group-containing group (meth) acrylate and the like. Among these, butyl acrylate, 2-ethylhexyl acrylate, isobornyl acrylate, phenoxyethyl acrylate, benzyl acrylate, and cyclohexyl acrylate are preferably used, and 2-ethylhexyl acrylate or isobornyl acrylate is particularly preferably used.

The polymerizable vinyl monomer may further have a functional group other than a vinyl group-containing group in the molecule. Examples of the functional group include an amide group in addition to the active hydrogen group described above, that is, a hydroxy group, a carboxy group, a thiol group, and a primary or secondary amino group. As the amino group, a tertiary amino group is particularly mentioned. Specific examples of the polymerizable vinyl monomer having such a functional group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) ) Hydroxyalkyl (meth) acrylates such as acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate; acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, Hydroxy group-containing acrylamides such as N-methylol methacrylamide; NN-dimethyl (meth) acrylamide, NN-diethyl (meth) acrylamide, N- (meth) acryloylmorpholine, Data) acrylic acid N-N-diethylaminoethyl, acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and ethylenically unsaturated carboxylic acids such as citraconic acid. Of these, 2-hydroxyethyl acrylate is preferably used.

Other polymerizable vinyl monomers include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene and α-methylstyrene. Styrene monomers such as butadiene, isoprene, chloroprene, etc .; nitrile monomers such as acrylonitrile, methacrylonitrile, etc .; acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide Amide monomers such as NN-dimethyl (meth) acrylamide, NN-diethyl (meth) acrylamide, N- (meth) acryloylmorpholine, N-vinylpyrrolidone; (meth) acrylic acid NN -Diethylaminoethyl, - (meth) acryloyl morpholine tertiary amino group-containing monomers such as are exemplified.

(1-2) Polymerizable vinyl prepolymer The polymerizable vinyl prepolymer is not particularly limited, and any conventionally known one can be used as appropriate, and is obtained by polymerizing the polymerizable vinyl monomer described above. It is preferred to use a polymerizable vinyl prepolymer.

In addition, when obtaining a polymerizable vinyl prepolymer by polymerizing the polymerizable vinyl monomer described above, one kind of the monomer may be polymerized alone, or a plurality of kinds may be copolymerized.

In addition, the polymerizable vinyl prepolymer may be obtained by free radical polymerization or may be obtained by living polymerization. In particular, the RAFT (Reversible Addition-Fragmentation Chain Transfer Polymerization) terminal is left. It may be a polymer.

The mass average molecular weight of the polymerizable vinyl prepolymer is preferably 6,000 or more, particularly preferably 7,500 or more, and more preferably 10,000 or more. The mass average molecular weight is preferably 1,500,000 or less, particularly preferably 1,000,000 or less, and more preferably 100,000 or less. It becomes easy to make the viscosity of a composition (x1) into a desired range because the said mass mean molecular weight is in the said range.

(1-3) Polyfunctional (meth) acrylate monomer The polyfunctional (meth) acrylate monomer is not particularly limited, and conventionally known ones can be appropriately used.

In particular, as the polyfunctional (meth) acrylate monomer, a monomer having two or more (meth) acryloyl groups in one molecule can be preferably exemplified. Examples of such monomers include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) phosphate ) Acrylate, di (acryloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate Rate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, bis (acryloxyethyl) hydroxy Ethyl isocyanurate, isocyanuric acid ethylene oxide modified diacrylate, isocyanuric acid ethylene oxide modified triacrylate, ε-caprolactone modified tris (acryloxyethyl) isocyanurate, diglycerin tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, propion Acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate And caprolactone-modified dipentaerythritol hexa (meth) acrylate.

(1-4) Polyfunctional (meth) acrylate oligomer The polyfunctional (meth) acrylate oligomer is not particularly limited, and conventionally known ones can be used as appropriate, but two or more in one molecule It is preferable to use a polyfunctional (meth) acrylate oligomer having a (meth) acryloyl group. Examples of such oligomers include urethane acrylates, polyester acrylates, epoxy acrylates, polyether acrylates, polybutadiene acrylates, silicone acrylates and the like.

The urethane acrylate oligomer is, for example, a polyurethane oligomer obtained by a reaction of a polyisocyanate with a compound such as polyalkylene polyol, polyether polyol, polyester polyol, hydrogenated isoprene having a hydroxyl group terminal, or hydrogenated butadiene having a hydroxyl group terminal. Can be obtained by esterification with (meth) acrylic acid or (meth) acrylic acid derivatives.

Here, examples of the polyalkylene polyol used for the production of the urethane acrylate oligomer include polypropylene glycol, polyethylene glycol, polybutylene glycol, polyhexylene glycol and the like, and it is particularly preferable to use polypropylene glycol. In addition, what is necessary is just to combine glycerol, a trimethylol propane, a triethanolamine, a pentaerythritol, an ethylenediamine, a diethylenetriamine, sorbitol, sucrose etc. suitably, when making the number of functional groups of the urethane acrylate oligomer obtained into 3 or more.

Examples of polyisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylene diisocyanate; aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate and diphenyl diisocyanate; alicyclic diisocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate. Among these, it is preferable to use an aliphatic diisocyanate, and it is particularly preferable to use hexamethylene diisocyanate. In addition, polyisocyanate can use not only bifunctional but trifunctional or more.

Examples of (meth) acrylic acid derivatives include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate, 2-isocyanate ethyl acrylate, 2-isocyanate ethyl methacrylate, and 1,1-bis (acrylic acid). Roxymethyl) ethyl isocyanate and the like, and 2-isocyanatoethyl acrylate is particularly preferable.

As another method for producing a urethane acrylate oligomer, a polyalkylene polyol, a polyether polyol, a polyester polyol, a hydroxy group-containing hydrogenated isoprene, a hydroxy group-terminated hydrogenated butadiene compound, an isocyanate alkyl ( A urethane acrylate oligomer can also be obtained by a reaction between the —N═C═O moiety of the (meth) acrylate. In this case, as the isocyanate alkyl (meth) acrylate, the above-mentioned 2-isocyanate ethyl acrylate, 2-isocyanate ethyl methacrylate, 1,1-bis (acryloxymethyl) ethyl isocyanate and the like can be used.

Polyester acrylate oligomers can be produced, for example, by esterifying the hydroxy groups of polyester oligomers having hydroxy groups at both ends obtained by condensation of polycarboxylic acid and polyhydric alcohol with (meth) acrylic acid, It can be obtained by esterifying the terminal hydroxy group of an oligomer obtained by adding an alkylene oxide to a carboxylic acid with (meth) acrylic acid.

The epoxy acrylate oligomer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it. Further, a carboxyl-modified epoxy acrylate oligomer obtained by partially modifying an epoxy acrylate oligomer with a dibasic carboxylic acid anhydride can also be used.

The polyether acrylate oligomer can be obtained, for example, by esterifying the hydroxy group of the polyether polyol with (meth) acrylic acid.

The mass average molecular weight of the polyfunctional (meth) acrylate oligomer is preferably 10,000 or more, and particularly preferably 20,000 or more. The mass average molecular weight is preferably 350,000 or less, particularly preferably 200,000 or less.
(2) Polymerization initiator It is preferable that the composition (x1) which concerns on this embodiment further contains a polymerization initiator. By containing the polymerization initiator, the composition (x1) can be efficiently cured.

The polymerization initiator is not particularly limited, and conventionally known polymerization initiators can be used, but it is preferable to select them according to the curing mode of the composition (x1). That is, when the composition (x1) is cured by irradiation with ultraviolet rays as active energy rays, it is preferable to use a photopolymerization initiator as a polymerization initiator. In addition, when the composition (x1) is cured by heating, it is preferable to use a thermal polymerization initiator. A photopolymerization initiator and a thermal polymerization initiator may be used in combination.

Examples of photopolymerization initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylamino Nzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2,4 , 6-trimethylbenzoyl-diphenyl-phosphine oxide and the like. These may be used alone or in combination of two or more.

Examples of the thermal polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, peroxides such as benzoyl peroxide and laurium peroxide, and azo compounds such as azobisisobutyronitrile. These may be used alone or in combination of two or more.

The content of the polymerization initiator in the composition (x1) is preferably 0.1 parts by mass or more, particularly preferably 0.3 parts by mass or more, with respect to 100 parts by mass of the polymerization component. Is preferably 0.5 parts by mass or more. Moreover, it is preferable that the said content is 10 mass parts or less with respect to 100 mass parts of polymerization components, It is especially preferable that it is 5 mass parts or less, Furthermore, it is preferable that it is 3 mass parts or less. When the content is 0.1 part by mass or more, curing of the composition (x1) can be efficiently advanced. On the other hand, when the content is 10 parts by mass or less, it is possible to eliminate or reduce the polymerization initiator remaining unreacted in curing, and it is easy to set the obtained pressure-sensitive adhesive to desired physical properties.

(3) Various additives In the composition (x1), various additives, for example, silane coupling agents, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, A filler, a refractive index adjusting agent, etc. can be added.
When these additives are contained, the content of each additive is independently preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass with respect to 100 parts by mass of the polymerization component. It is.
In one embodiment of the present invention, the composition (x1) may contain a small amount of a diluting solvent such as water or an organic solvent together with the above-mentioned various active ingredients, but it is preferable not to contain it.

In addition, since the heat-expandable base material (Y) contains heat-expandable particles, the pressure-sensitive adhesive sheet of the present invention exhibits heat peelability, so that the composition (x1) that is the pressure-sensitive adhesive layer (X1) forming material is used. It is not necessary to include thermally expandable particles. However, for the purpose of assisting heat peelability, the composition (x1) may contain a small amount of thermally expandable particles within a range not impairing the effects of the present invention, and the content of thermally expandable particles is determined by the composition (x1). ) Is preferably 0 to 50% by weight, more preferably 0 to 20% by weight, still more preferably 0 to 10% by weight, based on the total amount of active ingredients (100% by weight).

[Adhesive layer (X2)]
The pressure-sensitive adhesive layer (X2) included in the pressure-sensitive adhesive sheet of one embodiment of the present invention is a layer formed from the composition (x2) and has adhesiveness.
Suitable physical properties of the pressure-sensitive adhesive layer (X2) are the same as those of the pressure-sensitive adhesive layer (X1).
Moreover, about the composition (x2) which is a forming material of an adhesive layer (X2), the thing similar to the composition (x1) which is a forming material of an adhesive layer (X1) can be used.

[Release material]
As the release materials 13, 131, and 132 included in the pressure-sensitive adhesive sheet of one embodiment of the present invention, a release sheet that has been subjected to a double-sided release process, a release sheet that has been subjected to a single-sided release process, and the like are used. The thing etc. which apply | coated the release agent are mentioned.
In the pressure-sensitive adhesive sheet of one embodiment of the present invention, the two release materials 131 and the release material 132 that sandwich the laminate are preferably adjusted so that the difference in the release force is different.

Examples of the base material for the release material include papers such as high-quality paper, glassine paper, and kraft paper; polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; and olefins such as polypropylene resin and polyethylene resin. A plastic film such as a resin film;

Examples of the release agent include silicone-based resins, olefin-based resins, isoprene-based resins, rubber-based elastomers such as butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.

The thickness of the release material is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 170 μm, and still more preferably 35 to 80 μm.

≪Method for manufacturing adhesive sheet≫
It is preferable that the manufacturing method of the adhesive sheet of this invention is a method including the following process (1A) and (2A).
Since the manufacturing method of the adhesive sheet of this invention can reduce the number of processes at the time of manufacturing an adhesive sheet compared with the conventional manufacturing method, it can improve productivity.
Step (1A): A step of directly laminating a coating film (x1 ′) made of the composition (x1) and a coating film (y ′) made of the composition (y) in this order.
Step (2A): The coating film (x1 ′) and the coating film (y ′) are simultaneously irradiated with energy rays, and the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) are directly laminated in this order. Forming a laminated body.
Hereinafter, steps (1A) and (2A) will be described.

In the step (1A), as a method for forming the coating film (x1 ′) and the coating film (y ′), for example, after the coating film (x1 ′) is formed, the coating film (x1 ′) is coated on the coating film (x1 ′). ') May be sequentially formed, but from the viewpoint of productivity and interfacial adhesion, the composition (x1) and the composition (y) are simultaneously applied to form the coating film (x1') and the coating film ( A method of simultaneously forming y ′) is preferred.
In addition, from a viewpoint of handleability, it is preferable to form the coating film (x1 ′) or the coating film (y ′) on the release treatment surface of the release material.

As the coater used for coating the composition (x1) and the composition (y) when sequentially forming the coating film (x1 ′) and the coating film (y ′), for example, a spin coater, a spray coater, a bar coater, Examples include knife coaters, roll coaters, knife roll coaters, blade coaters, gravure coaters, curtain coaters, and die coaters.

Examples of the coater used when the composition (x1) and the composition (y) are simultaneously applied include a multilayer coater, and specifically, a multilayer curtain coater, a multilayer die coater, and the like. Among these, a multilayer die coater is preferable from the viewpoint of operability.

In the step (2A), the coating (x1 ′) and the coating (y ′) are simultaneously irradiated with energy rays to form the laminate.
In this energy ray irradiation process, a mixed layer is formed at the interface between the coating film (x1 ′) and the coating film (y ′), and the adhesive resin in the coating film (x1 ′) and the resin in the coating film (y ′). It is considered that the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the heat-expandable base material (Y) is improved by irradiating with energy rays in a state where they are intertwined with each other.

Examples of the energy ray irradiation of the coating film in the step (2A) include ultraviolet ray irradiation and electron beam irradiation, but ultraviolet ray irradiation is preferable from the viewpoint of preventing unnecessary reactions.
UV irradiation, high-pressure mercury lamp, a metal halide lamp, an electrodeless UV lamp, UV-LED, can be effected by a xenon lamp or the like, the dose of ultraviolet ray is illuminance 50 mW / cm ² or more, is 1000 mW / cm ² or less It is preferable. Amount is preferably at 50 mJ / cm ² or more, more preferably 80 mJ / cm ² or more, and particularly preferably 200 mJ / cm ² or more. Further, the light amount is preferably at 10000 mJ / cm ² or less, more preferably 5000 mJ / cm ² or less, particularly preferably 2000 mJ / cm ² or less. On the other hand, the electron beam irradiation can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably 10 krad or more and 1000 krad or less.

When manufacturing the adhesive sheet which has a laminated body which further contains the adhesive layer (X2) which is an adhesive sheet of 1 aspect of this invention, the manufacturing method of this invention is the adhesive of a thermally expansible base material (Y). If it is a method further including the process of forming an adhesive layer (X2) on the surface on the opposite side to a layer (X1), it will not specifically limit. For example, the manufacturing method of the following embodiment (A) and the manufacturing method of embodiment (B) are mentioned, and the viewpoint of the interfacial adhesion between the productivity and the thermally expandable substrate (Y) and the pressure-sensitive adhesive layer (X2). To the embodiment (B) is more preferable.

The manufacturing method of the embodiment (A) includes the following steps (3A-1) or (3A-2) in addition to the steps (1A) and (2A) described above.
Step (3A-1): A coating film (x2 ′) comprising the composition (x2) is formed on the surface of the thermally expandable substrate (Y) obtained in the step (2A), and the coating film A step of irradiating (x2 ′) with energy rays.
Step (3A-2): The composition (x2) is applied on the release treatment surface of the release material to form a coating film (x2 ′), and the coating film (x2 ′) is irradiated with energy rays to adhere The step of forming the adhesive layer (X2) in advance and directly sticking the pressure-sensitive adhesive layer (X2) formed on the release material onto the surface of the thermally expandable substrate (Y) obtained in the step (2A) .

The method of forming the coating film (x2 ′) in the steps (3A-1) and (3A-2) is, for example, a spin coater, spray coater, bar coater, knife coater, roll coater, knife roll coater, blade coater, gravure coater. , Curtain coater, die coater and the like.

The energy beam irradiation conditions for the coating film (x2 ′) in the steps (3A-1) and (3A-2) are the same as those for the energy beam irradiation of the coating film in the step (2A).

In Steps (3A-1) and (3A-2), Step (3A-1) is preferable from the viewpoint of productivity and interfacial adhesion between the thermally expandable substrate (Y) and the pressure-sensitive adhesive layer (X2).

The manufacturing method of embodiment (B) includes the following steps (1B) and (2B).
Step (1B): a coating film (x1 ′) composed of the composition (x1), a coating film (y ′) composed of the composition (y), and a coating film (x2 ′) composed of the composition (x2) A process of directly stacking layers in this order.
-Process (2B): A coating film (x1 '), a coating film (y'), and a coating film (x2 ') are simultaneously irradiated with energy rays, and a pressure-sensitive adhesive layer (X1) and a thermally expandable substrate (Y) And a step of forming a laminate in which the pressure-sensitive adhesive layer (X2) is directly laminated in this order.
Hereinafter, steps (1B) and (2B) will be described.

In the step (1B), as a method for forming the coating film (x1 ′), the coating film (y ′), and the coating film (x2 ′), for example, after forming the coating film (x1 ′), the coating film (x1 A sequential formation method may be used in which a coating film (y ') is formed on') and a coating film (x2 ') is further formed on the coating film (y'). From the viewpoint of productivity, the composition ( It is preferable to apply x1), the composition (y), and the composition (x2) at the same time to form the coating film (x1 ′), the coating film (y ′), and the coating film (x2 ′) at the same time.
In addition, it is preferable to form a coating film (x1 ') or (x2') on the peeling process surface of a peeling material from a viewpoint of handleability and productivity.

As a coater used when forming each coating film sequentially, each coater mentioned above etc. are mentioned, for example.
Moreover, as a coater used when apply | coating a composition (x1), a composition (y), and a composition (x2) simultaneously, the multilayer coater which can apply | coat at least 3 layers simultaneously is mentioned. Specifically, a multilayer curtain coater, a multilayer die coater, etc. are mentioned. Among these, from the viewpoint of operability, a multilayer die coater capable of simultaneously applying three or more layers is preferable.

In the step (2B), the coating film (x1 ′), the coating film (y ′), and the coating film (x2 ′) are simultaneously irradiated with energy rays to form the laminate.
In this energy ray irradiation process, a mixed layer is formed at the interface between the coating film (x1 ′) and the coating film (y ′), and the adhesive resin in the coating film (x1 ′) and the resin in the coating film (y ′). Is cured by irradiating with energy rays in an intertwined state, whereby the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) is improved, and the coating film (y ′) and the coating film (X2 ') at the interface, a mixed layer is formed, and the resin in the coating film (y') and the adhesive resin in the coating film (x2 ') are entangled and cured by irradiation with energy rays. It is considered that the interfacial adhesion between the expandable substrate (Y) and the pressure-sensitive adhesive layer (X2) is improved.

The energy ray irradiation of the coating film in the step (2B) is the same as the energy ray irradiation of the coating film in the step (2A).

≪Use of adhesive sheet≫
The pressure-sensitive adhesive sheet of the present invention is useful as a temporary fixing means for an object during the manufacturing process of building materials, interior materials, electronic components, and the like, and is preferably used as a temporary fixing means for a semiconductor chip during the manufacturing process of a semiconductor device. it can. In particular, a semiconductor package (FOWLP (Fan out Wafer) in which a rewiring layer is provided on the surface of a semiconductor chip sealed with a sealing resin, and solder balls and the semiconductor chip are electrically connected via the rewiring layer. It can be suitably used as a temporary fixing means at the time of manufacturing (called Level Package).

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to the following examples. In addition, the physical-property value in the following manufacture examples and Examples is a value measured by the following method.

<Mass average molecular weight (Mw)>
Using a gel permeation chromatograph (product name “HLC-8020” manufactured by Tosoh Corporation), measurement was performed under the following conditions, and values measured in terms of standard polystyrene were used.
(Measurement condition)
Column: “TSK guard column HXL-L”, “TSK gel G2500HXL”, “TSK gel G2000HXL”, and “TSK gel G1000HXL” (both manufactured by Tosoh Corporation) Column temperature: 40 ° C.
・ Developing solvent: Tetrahydrofuran ・ Flow rate: 1.0 mL / min

<Thickness of laminate>
It was measured using a constant pressure thickness measuring instrument (model number: “PG-02J”, standard: conforming to JIS K6783, Z1702, Z1709) manufactured by Teclock Co., Ltd.
Specifically, after measuring the total thickness of the pressure-sensitive adhesive sheet to be measured, a value obtained by subtracting the thickness of the release material measured in advance was defined as “the thickness of the laminate”.

<Thickness of each layer>
Using a scanning electron microscope (manufactured by Hitachi, Ltd., product name “S-4700”), the cross section in the thickness direction of the laminate was observed, and the adhesive layer (X1), heat, The thickness ratio of each of the expandable substrate (Y) and the pressure-sensitive adhesive layer (X2) was measured.
And based on the thickness ratio of each layer, the thickness of each layer was computed from the actual value of the "thickness of a laminated body" measured by the above-mentioned method.

<Average particle diameter (D ₅₀ ) of thermally expandable particles, 90% particle diameter (D ₉₀ )>
The particle distribution of the thermally expandable particles before expansion at 23 ° C. was measured using a laser diffraction particle size distribution measuring apparatus (for example, product name “Mastersizer 3000” manufactured by Malvern).
The particle diameters corresponding to 50% and 90% of the cumulative volume frequency calculated from the smaller particle diameter of the particle distribution are expressed as “average particle diameter (D ₅₀ ) of thermally expandable particles” and “thermally expandable particles”, respectively. 90% particle diameter (D ₉₀ ).

<Probe tack value>
Laminate sample (heavy release film / thermally expandable substrate / light release film) so that the thickness of the heat expandable substrate to be measured is 20 μm in a state of being sandwiched between the later described heavy release film and light release film It was created. The prepared sample was cut into a square with a side of 10 mm and then allowed to stand for 24 hours in an environment of 23 ° C. and 50% RH (relative humidity) to remove the light release film and the heavy release film as a test sample.
Then, in an environment of 23 ° C. and 50% RH (relative humidity), using a tacking tester (manufactured by Nippon Special Instrument Co., Ltd., product name “NTS-4800”), the probe tack value on the surface of the test sample is calculated. , 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 at a contact load of 0.98 N / cm ² for 1 second, and then the probe is moved at a speed of 10 mm / sec. The force required to separate from the surface was measured. And the measured value was made into the probe tack value of the test sample.

<Storage elastic modulus E 'of thermally expandable substrate>
The thermal expansible substrate to be measured was 5 mm long × 30 mm wide × 200 μm thick, and the sample from which the release material was removed was used as a test sample.
Using a dynamic viscoelasticity measuring apparatus (TA Instruments, product name “DMAQ800”), a test start temperature of 0 ° C., a test end temperature of 300 ° C., a temperature increase rate of 3 ° C./min, a frequency of 1 Hz, and an amplitude of 20 μm Under the conditions, the storage elastic modulus E ′ of the test sample at a predetermined temperature was measured.

<Interfacial adhesion>
The pressure-sensitive adhesive sheets produced in Examples and Comparative Examples were cut into a size of 50 mm length × 30 mm width. And it evaluated based on JISK5600-5-6.
According to the following criteria, the interface between the adhesive layer (X1) and the thermally expandable substrate (Y) and the interface between the adhesive layer (X2) and the thermally expandable substrate (Y) Adhesion was evaluated.
A: The classification according to JIS K5600-5-6 was “0 (best)” for the two interfaces.
B: At least one of the interfaces was classified into “1” to “4” according to JIS K5600-5-6.
F: At least one of the interfaces was “5 (worst)” according to JIS K5600-5-6.

<Measurement of adhesive strength of adhesive sheet before and after heating>
The light release film of the produced pressure-sensitive adhesive sheet was removed, and a 50 μm thick polyethylene terephthalate (PET) film (product name “COSMO SHINE A4100” manufactured by Toyobo Co., Ltd.) was formed on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X2). ) To obtain an adhesive sheet with a substrate. And the heavy peeling film of the said adhesive sheet was also removed, it affixed on the stainless steel plate (SUS304 360th polishing) which is a to-be-adhered body, and left still for 24 hours in the environment of 23 degreeC and 50% RH (relative humidity). This was used as a test sample.
Then, using the above test sample, in an environment of 23 ° C. and 50% RH (relative humidity), in accordance with JIS Z0237: 2000, by a 180 ° peeling method at a pulling speed of 300 mm / min at 23 ° C. The adhesive strength was measured.
In addition, the above test sample is heated on a hot plate for 3 minutes at 240 ° C., which is equal to or higher than the expansion start temperature (208 ° C.) of the thermally expandable particles, and the standard environment (23 ° C., 50% RH (relative humidity)). Then, the adhesive strength after heating at a temperature equal to or higher than the expansion start temperature was also measured at a pulling rate of 300 mm / min by a 180 ° peeling method based on JIS Z0237: 2000.
In addition, when measurement of adhesive force was so difficult that it could not be affixed to the stainless steel plate which is a to-be-adhered body, it was set as "impossible to measure" and the adhesive force was set to 0 (N / 25mm).

Details of the thermally expandable particles and the release material used in the formation of each layer in the following production examples are as follows.

<Thermal expandable particles>
Thermally expandable particles (i): manufactured by Kureha Co., Ltd., product name “S2640”, expansion start temperature (t) = 208 ° C., average particle size (D ₅₀ ) = 24 μm, 90% particle size (D ₉₀ ) = 49 μm .
<Release material>
Heavy release film: manufactured by Lintec Corporation, product name “SP-PET382150”, a polyethylene terephthalate (PET) film provided with a release agent layer formed from a silicone release agent on one side, thickness: 38 μm.
Light release film: manufactured by Lintec Co., Ltd., product name “SP-PET381031”, a PET film provided with a release agent layer formed from a silicone release agent on one side, thickness: 38 μm.

Production Example 1 (Preparation of composition (x1))
(1) Synthesis of urethane acrylate oligomer 100 parts by mass of polypropylene glycol having a mass average molecular weight of 3000 (solid content converted value; the same shall apply hereinafter), 4 parts by mass of hexamethylene diisocyanate, and 0.02 parts by mass of dioctyltin dilaurate were mixed. The reaction product was obtained by stirring at 80 ° C. for 6 hours. When the IR spectrum of the obtained reaction product was measured by infrared spectroscopy, it was confirmed that the isocyanate group almost disappeared.
Thereafter, 1 part by mass of 2-isocyanatoethyl acrylate was mixed with the total amount of the reaction product obtained and stirred at 80 ° C. for 3 hours to obtain a urethane acrylate oligomer. The IR spectrum of the obtained urethane acrylate oligomer was measured by infrared spectroscopy, and it was confirmed that the isocyanate group had almost disappeared. Moreover, when the molecular weight of the obtained urethane acrylate-type oligomer was measured by the method mentioned later, it was mass average molecular weight (Mw) 25,000.
(2) Preparation of liquid mixture As described above, 40 parts by mass of 2-ethylhexyl acrylate as a polymerizable vinyl monomer, 20 parts by mass of isobornyl acrylate as a polymerizable vinyl monomer, and a polyfunctional (meth) acrylate oligomer 40 parts by mass of the prepared urethane acrylate oligomer was mixed and stirred to obtain a liquid mixture.
(3) Preparation of energy ray-curable acrylic copolymer (i) 100 parts by mass of the liquid mixture prepared above (in terms of solid content; the same applies hereinafter) and 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator (BASF, product name “Irgacure 184”) 0.5 parts by mass was mixed to obtain a solventless composition (x1) of an energy ray-curable acrylic pressure-sensitive adhesive.
In addition, the same composition (x1) described here was also used for the composition (x2) as a material for forming the layer (X2) described later.

Production Example 2 (Preparation of composition (y))
A terminal isocyanate urethane prepolymer obtained by reacting an ester-type diol with isophorone diisocyanate (IPDI) is reacted with 2-hydroxyethyl acrylate to produce a bifunctional acrylic urethane oligomer having a mass average molecular weight (Mw) of 5000. Obtained.
Then, 40% by mass (solid content ratio) of the acrylic urethane-based oligomer synthesized as described above, 40% by mass (solid content ratio) of isobornyl acrylate (IBXA), and phenylhydroxypropyl acrylate (HPPA) as an energy ray polymerizable monomer ) 20% by mass (solid content ratio), and 1-hydroxycyclohexyl phenyl ketone (BASF) as a photopolymerization initiator with respect to the total amount (100 parts by mass) of the acrylic urethane oligomer and the energy ray polymerizable monomer. Product name “Irgacure 184”) 2.0 parts by mass (solid content ratio), and 0.2 parts by mass (solid content ratio) phthalocyanine pigment as an additive. Prepared.
And the said heat | fever expansible particle (i) was mix | blended with the said energy-beam curable composition, and the solventless type composition (y) which does not contain a solvent was prepared.
In addition, content of the thermally expansible particle (i) with respect to the whole quantity (100 mass%) of a composition (y) was 20 mass%.

Example 1
(1) Formation of coating film On the release agent layer of the heavy release film as a release material, the composition (x1) prepared in Production Example 1, the composition (y) prepared in Production Example 2, and Production Example 1 The composition (x2) prepared in (1) was simultaneously applied in this order using a multilayer die coater (width: 250 mm), and the coating film (x1 ′), coating film (y ′) and coating film (x2 ′) were formed. They were formed simultaneously in this order.
(2) Energy ray irradiation treatment The formed coating film (x1 ′), coating film (y ′) and coating film (x2 ′) were irradiated with an illuminance of 160 mW / cm ² and a light amount of 1000 mJ / cm ² using an ultraviolet irradiation device. The coating film was cured by irradiating with ultraviolet rays under conditions to form a laminate in which the layer (X1), the layer (Y), and the layer (X2) were directly laminated in this order from the release agent layer of the heavy release film. The above illuminance and light intensity during ultraviolet irradiation are values measured using an illuminance / light meter (product name “UV Power Pack II” manufactured by EIT).
And the release agent layer of the light release film was laminated | stacked on the surface of the layer (X2) exposed, and the adhesive sheet of Example 1 was obtained.

Example 2
The composition (x1), the composition (y), and the composition (x2) were formed so that the thicknesses of the layer (X1), the layer (Y), and the layer (X2) were as shown in Table 1, respectively. A pressure-sensitive adhesive sheet of Example 2 was obtained using the same method as Example 1 except that the coating amount was changed.

Comparative Example 1
On the release agent layer of the heavy release film as a release material, a coating film (x1 ′) made of the composition (x1) prepared in Production Example 1 is formed, and an illuminance of 160 mW / cm ² using an ultraviolet irradiation device, The layer (X1) was formed by irradiating with ultraviolet rays under the condition of a light amount of 1000 mJ / cm ² to cure the coating film.
Moreover, the coating film (y ') which consists of a composition (y) prepared by manufacture example 2 is formed on the release agent layer of the light release film prepared separately from the release film on layer (X1), and ultraviolet irradiation Using the apparatus, the layer (Y) was formed by ultraviolet irradiation under the same conditions as those described above.
Furthermore, a coating film (x2 ′) is formed on the release agent layer of a light release film prepared separately using the composition (x2) prepared in Production Example 1, and the above-described irradiation is performed using an ultraviolet irradiation device. The layer (X2) was formed by irradiation with ultraviolet rays under the same conditions.
Then, the layer (Y) is laminated on the surface of the exposed layer (X1), the light release film on the layer (Y) is removed, and the layer (Y) is exposed on the surface. (X2) was laminated | stacked and the adhesive sheet of the comparative example 1 laminated | stacked in order of the heavy release film, the layer (X1), the layer (Y), the layer (X2), and the light release film was obtained.
The thickness of the laminated body which the adhesive sheet produced in the Example and the comparative example has, and the thickness of the layer (X1), layer (Y), and layer (X2) which comprise the said laminated body are used for the above-mentioned method. Measured in conformity. The measurement results are shown in Table 1.

DESCRIPTION OF SYMBOLS 1a, 1b Adhesive sheet 2a, 2b Double-sided adhesive sheet 10 Laminated body 11 Thermally expansible base material (Y)
12, 121 Adhesive layer (X1)
122 Adhesive layer (X2)
13, 131, 132 Release material

Claims (9)

A pressure-sensitive adhesive sheet having a laminate in which a pressure-sensitive adhesive layer (X1) and a non-adhesive thermally expandable substrate (Y) are directly laminated in this order,
The laminate is
A coating film (x1 ′) comprising a composition (x1) which is a forming material of the pressure-sensitive adhesive layer (X1);
A coating film (y ′) comprising a composition (y) containing a resin and thermally expandable particles, which is a forming material of the thermally expandable substrate (Y),
Are directly laminated in this order, and then the pressure-sensitive adhesive sheet is formed by simultaneously irradiating the coating film (x1 ′) and the coating film (y ′) with energy rays. The pressure-sensitive adhesive sheet according to claim 1, wherein the energy ray irradiation is ultraviolet irradiation. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the thermally expandable substrate (Y) satisfies the following requirement (1).
Requirement (1): The storage elastic modulus E ′ (t) of the thermally expandable substrate (Y) at the expansion start temperature (t) of the thermally expandable particles is 1.0 × 10 ⁷ Pa or less. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the thermally expandable substrate (Y) satisfies the following requirement (2).
Requirement (2): The storage elastic modulus E ′ (23) of the thermally expandable substrate (Y) at 23 ° C. is 1.0 × 10 ⁶ Pa or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the thickness of the thermally expandable substrate (Y) is 10 to 1000 µm. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the probe tack value on the surface of the thermally expandable substrate (Y) is less than 50 mN / 5 mmφ. The said laminated body further contains an adhesive layer (X2), and the adhesive layer (X1), the thermally expansible base material (Y), and the adhesive layer (X2) are directly laminated | stacked in this order. The pressure-sensitive adhesive sheet according to any one of 6 to 6. The laminate is
A coating film (x1 ′) comprising a composition (x1) which is a forming material of the pressure-sensitive adhesive layer (X1);
A coating film (y ′) comprising a composition (y) containing a resin and thermally expandable particles, which is a forming material of the thermally expandable substrate (Y),
A coating film (x2 ′) comprising a composition (x2) which is a forming material of the pressure-sensitive adhesive layer (X2);
The pressure-sensitive adhesive sheet according to claim 7, which is formed by directly laminating the films in this order and then simultaneously irradiating the coating films (x1 ′), (y ′) and (x2 ′) with energy rays. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein an average particle diameter of the thermally expandable particles before expansion at 23 ° C is 3 to 100 µm.

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