WO2018181768A1

WO2018181768A1 - Adhesive sheet

Info

Publication number: WO2018181768A1
Application number: PCT/JP2018/013355
Authority: WO
Inventors: 高志阿久津; 揮一郎加藤; 晃司土渕
Original assignee: リンテック株式会社
Priority date: 2017-03-31
Filing date: 2018-03-29
Publication date: 2018-10-04
Also published as: TW201842115A; CN110506089A; KR102573604B1; KR20190133168A; JP6764525B2; TWI825012B; JPWO2018181768A1; CN110506089B

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) containing an adhesive resin, and a material for forming the thermally expandable substrate (Y), namely, a coating film (y') comprising a composition (y) containing a resin and thermally expandable particles, then simultaneously drying the coating film (x1') and the coating film (y'). 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 [8].
[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) containing an adhesive resin, 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 laminated | stacked directly in this order, Then, a coating sheet (x1 ') and a coating film (y') are dried simultaneously, and the adhesive sheet is formed.
[2] The pressure-sensitive adhesive sheet according to [1], 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.
[3] The pressure-sensitive adhesive sheet according to [1] or [2], 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.
[4] The pressure-sensitive adhesive sheet according to any one of [1] to [3] above, wherein the thickness of the thermally expandable substrate (Y) is 5 to 140 μm.
[5] The pressure-sensitive adhesive sheet according to any one of the above [1] to [4], wherein the probe tack value on the surface of the thermally expandable substrate (Y) is less than 50 mN / 5 mmφ.
[6] 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 [5] above.
[7] The laminate is
A coating film (x1 ′) comprising a composition (x1) containing an adhesive resin, 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) containing an adhesive resin, which is a material for forming the adhesive layer (X2);
Are directly laminated in this order, and then the coated sheets (x1 ′), (y ′) and (x2 ′) are simultaneously dried to form the pressure-sensitive adhesive sheet according to [6] above.
[8] The pressure-sensitive adhesive sheet according to any one of [1] to [7], 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 material for forming the pressure-sensitive adhesive layer (X1), and is a coating film (x1 ′) made of a composition (x1) containing a pressure-sensitive resin and a thermally expandable substrate (Y). After directly laminating the coating film (y ′) made of the composition (y) containing the resin and the heat-expandable particles, in this order, the coating film (x1 ′) and the coating film (y ′) It was formed by drying at the same time.
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 ), A coating film (x1 ′) made of a composition (x1) containing an adhesive resin, and a composition containing a resin and thermally expandable particles, which is a forming material of the thermally expandable substrate (Y). The coating film (y ′) made of the product (y) is directly laminated in this order, and then the coating film (x1 ′) and the coating film (y ′) are dried at the same time.
In the present invention, since the coating film (x1 ′) and the coating film (y ′) are dried “simultaneously” to form a laminate, the coating film (x1 ′) and the coating film (y ′) are “separated”. Compared with the method of drying and forming a laminated body, the interface adhesiveness of an adhesive layer (X1) and a thermally expansible base material (Y) can be improved.
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 drying '), 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 substrate ( It is considered that the interfacial adhesion with Y) is improved.

The following method is mentioned as an example of the method of drying a coating film (x1 ') and a coating film (y') "separately", and forming a laminated body.
A composition (x1) containing an adhesive resin is applied onto a release-treated surface of a release material such as a release film to form a coating film (x1 ′), and the coating film (x1 ′) is dried to form an adhesive layer. (X1) is formed. 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 dried 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 the laminate by drying the coating film (x1 ′) and the coating film (y ′) “separately” as described above, the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) However, since they 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 at the same time, 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 dried. Is formed. By applying the composition (x1) and the composition (y) at the same time, it becomes difficult to form a dry film of the thin film on the surface of the coating film as compared with the case of sequentially applying each composition. Interfacial adhesion between 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. In addition, an adhesive layer (X2) is a layer formed from the composition (x2) containing adhesive resin.
Examples of a method for forming a laminate further including the above-mentioned pressure-sensitive adhesive layer (X2) include, for example, a method in which the composition (x2) is heated and melted and extrusion-laminated on the expandable substrate (Y), or a composition ( There is a method in which x2) is applied on the expandable substrate (Y) to form a coating film (x2 ′), and the coating film (x2 ′) is dried to form. Further, for example, the pressure-sensitive adhesive layer (X2) prepared in advance by a method such as extrusion molding or drying the coating film (x2 ′) may be directly pasted on the expandable substrate (Y).

The laminate further comprising the pressure-sensitive adhesive layer (X2) is preferably a coating film (x1 ′) made of a composition (x1) containing a pressure-sensitive resin, which is a material for forming the pressure-sensitive adhesive layer (X1). A coating material (y ′) composed of a composition (y) containing a resin and thermally expandable particles, which is a forming material of the thermally expandable base material (Y), and an adhesive material which is a forming material of the adhesive layer (X2) The coating film (x2 ′) composed of the composition (x2) containing the conductive resin is directly laminated in this order, and then the coating films (x1 ′), (y ′) and (x2 ′) are simultaneously dried. It is a thing.
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 dried at the same time.
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 ') Even when (y ′) and (x2 ′) are directly laminated in this order, and the coating films (x1 ′), (y ′) and (x2 ′) are simultaneously dried, Regarding 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), the same circumstances as described above exist, and as such It must be specified by a simple manufacturing method.

In the present invention, the “coating film” is a film formed from a composition as a forming material by a known coating method, and the residual ratio of volatile components such as a solvent contained in the film is This refers to those in a state of 10 to 100% by mass with respect to 100% by mass of the total amount of volatile components contained in the composition before coating.
That is, in the present invention, the coating films (x1 ′), (y ′), and (x2 ′) contain a certain amount of a volatile component such as a solvent. By drying these coating films, the volatile components are removed, and the pressure-sensitive adhesive layer (X1), the thermally expandable substrate (Y), and the pressure-sensitive adhesive layer (X2) are formed.

In addition, about the method of forming a coating film (x1 '), (y'), and (x2 '), and the drying conditions of the formed coating film, respectively, it describes in the item of the below-mentioned "manufacturing method of an adhesive sheet". It is as follows.

The thickness of the laminate of the pressure-sensitive adhesive sheet of the present invention is preferably 10 to 150 μm, more preferably 15 to 125 μm, still more preferably 20 to 100 μm, and still more preferably 25 to 75 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 60 μm, more preferably 2 to 50 μm, still more preferably 3 to 40 μm, and still more preferably 5 to 30 μm.

The thickness of the heat-expandable base material (Y) of the pressure-sensitive adhesive sheet of the present invention is preferably 5 to 140 μm, more preferably 9 to 110 μm, still more preferably 13 to 80 μm, and still more preferably 17 to 50 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 60 μm, more preferably 2 to 50 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 3.0 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 peeling, it is preferably 20 or less, more preferably 15 or less, still more preferably 10 or less, and even more preferably 5 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 3.0 or more, preferably 20 or less, more preferably 15 or less, still more preferably 10 or less, and still more preferably 5 or less.

In addition, as described above, the laminate of the pressure-sensitive adhesive sheet of the present invention has a mixed layer between the two coating films in the drying process of the coating film, and the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) And the interface between the thermally expandable base material (Y) and the pressure-sensitive adhesive layer (X2) may become so unclear that they 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 drying a coating film (y ′) made of a composition (y) containing a resin and heat-expandable particles, It is an 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 one mode of the present invention, in the range which does not impair the effect of the present invention, it contains the additive for the substrate contained in the substrate which the diluting solvent and / or the general adhesive sheet has as needed. Also good.

(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.

The mass average molecular weight (Mw) of the resin contained in the composition (y) is preferably 1,000 to 1,000,000, more preferably 1,000 to 700,000, and still more preferably 1,000 to 500,000.
Further, when the resin is a copolymer having two or more kinds of structural units, the form of the copolymer is not particularly limited, and any of a block copolymer, a random copolymer, and a graft copolymer It may be.

The content of the resin is preferably 50 to 99% by mass, more preferably 60 to 95% by mass, and still more preferably 65 to 90% by mass with respect to the total amount (100% by mass) of the active ingredients of the composition (y). %, More preferably 70 to 85% by mass.

It should be noted that the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the heat-expandable base material (Y) and, if the pressure-sensitive adhesive layer (X2) is present, the heat-expandable base material (Y) and the pressure-sensitive adhesive layer From the viewpoint of further improving the interfacial adhesion with the interface with (X2), the resin contained in the resin composition (y) includes one or more selected from acrylic urethane resins and olefin resins. Is preferred.
Moreover, as said acrylic urethane type resin, the following resin (U1) is preferable.
An acrylic urethane resin (U1) obtained by polymerizing a urethane prepolymer (UP) and a vinyl compound containing a (meth) acrylic acid ester.

The acrylic urethane-based resin (U1) has a structural unit derived from a vinyl compound containing a (meth) acrylic acid ester at both ends of the linear urethane prepolymer while having the main chain of the linear urethane prepolymer as a skeleton. is there.
In the acrylic urethane resin (U1), since the site derived from the linear urethane polymer is interposed between the acrylic sites in the main chain skeleton, the distance between the crosslinking points becomes long, and the molecular structure thereof is a two-dimensional structure (network structure). It is easy to become.
Moreover, since the urethane prepolymer of the main chain is linear, the stretching effect is high when an external force is applied.
Furthermore, the side chain of the structural unit derived from the vinyl compound containing (meth) acrylic acid ester is easily entangled with the adhesive resin contained in the adhesive layer (X1) and the adhesive resin contained in the adhesive layer (X2). It has a structure.
Therefore, the acrylic urethane-based resin (U1) is thermally expandable when the adhesiveness between the adhesive layer (X1) and the thermally expandable substrate (Y) and the adhesive layer (X2) are present. It is thought that it can contribute to the improvement of the interfacial adhesion between the base material (Y) and the adhesive layer (X2).

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

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) serving as the main chain of the acrylic urethane resin (U1) is a reaction product of a diol and a diisocyanate, and is a straight chain having ethylenically unsaturated groups at both ends. A urethane prepolymer is preferred.
As a method for introducing an ethylenically unsaturated group into both ends of the linear urethane prepolymer, an NCO group at the end of the linear urethane prepolymer obtained by reacting a diol and a diisocyanate compound, and a hydroxyalkyl (meth) acrylate And a method of reacting with.

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

As a vinyl compound used as the side chain of acrylic urethane resin (U1), at least (meth) acrylic acid ester is included.
The (meth) acrylic acid ester is preferably one or more selected from alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates, and more preferably used in combination with alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates.

When alkyl (meth) acrylate and hydroxyalkyl (meth) acrylate are used in combination, the proportion of hydroxyalkyl (meth) acrylate to 100 parts by mass of alkyl (meth) acrylate is preferably 0.1 to 100 parts by mass, The amount is preferably 0.5 to 30 parts by mass, more preferably 1.0 to 20 parts by mass, and still more preferably 1.5 to 10 parts by mass.

The carbon number of the alkyl group of the alkyl (meth) acrylate is preferably 1 to 24, more preferably 1 to 12, still more preferably 1 to 8, and still more preferably 1 to 3.

Moreover, as hydroxyalkyl (meth) acrylate, the same thing as the hydroxyalkyl (meth) acrylate used in order to introduce | transduce an ethylenically unsaturated group into the both ends of the above-mentioned linear urethane prepolymer is mentioned.

Examples of vinyl compounds other than (meth) acrylic acid esters include aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, and vinyl toluene; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; vinyl acetate and vinyl propionate. Polar group-containing monomers such as (meth) acrylonitrile, N-vinylpyrrolidone, (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, and meta (acrylamide).
These may be used alone or in combination of two or more.

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

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

The acrylic urethane-based resin (U1) used in one embodiment of the present invention is obtained by mixing a urethane prepolymer (UP) and a vinyl compound containing a (meth) acrylic acid ester and polymerizing both.
The polymerization is preferably performed by adding a radical initiator.

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

{Olefin resin}
The olefin resin suitable as the resin contained in the composition (y) is a polymer having at least a structural unit derived from an olefin monomer.
The olefin monomer is preferably an α-olefin having 2 to 8 carbon atoms, and specifically includes ethylene, propylene, butylene, isobutylene, 1-hexene and the like.
Among these, ethylene and propylene are preferable.

Specific olefinic resins, for example, ultra low density polyethylene (VLDPE, density: 880 kg / ^{m 3} or more 910 kg / ^m less than ^3), low density polyethylene (LDPE, density: 910 kg / ^{m 3} or more 915 kg / ^m less than ³ ), Medium density polyethylene (MDPE, density: 915 kg / m ³ or more and less than 942 kg / m ³ ), high density polyethylene (HDPE, density: 942 kg / m ³ or more), linear low density polyethylene, etc .; 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); ethylene-propylene Olefinic terpolymers such as-(5-ethylidene-2-norbornene); and the like.

In one embodiment of the present invention, the olefin resin may be a modified olefin resin further modified by one or more selected from acid modification, hydroxyl group modification, and acrylic modification.

For example, as an acid-modified olefin resin obtained by subjecting an olefin resin to acid modification, a modified polymer obtained by graft polymerization of the above-mentioned unmodified olefin resin with an unsaturated carboxylic acid or its anhydride. Is mentioned.
Examples of the unsaturated carboxylic acid or anhydride thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, tetrahydrophthalic acid, aconitic acid, (meth) acrylic acid, maleic anhydride, itaconic anhydride. , Glutaconic anhydride, citraconic anhydride, aconitic anhydride, norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride, and the like.
In addition, unsaturated carboxylic acid or its anhydride may be used independently and may use 2 or more types together.

As an acrylic modified olefin resin obtained by subjecting an olefin resin to acrylic modification, a modification obtained by graft polymerization of an alkyl (meth) acrylate as a side chain to the above-mentioned unmodified olefin resin as a main chain. A polymer is mentioned.
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.
As said alkyl (meth) acrylate, the same thing as the compound which can be selected as a below-mentioned monomer (a1 ') is mentioned, for example.

Examples of the hydroxyl group-modified olefin resin obtained by subjecting an olefin resin to hydroxyl group modification include a modified polymer obtained by graft polymerization of a hydroxyl group-containing compound to the above-mentioned unmodified olefin resin, which is the main chain.
Examples of the hydroxyl group-containing compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl. Examples thereof include hydroxyalkyl (meth) acrylates such as (meth) acrylate and 4-hydroxybutyl (meth) acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol.

{Resin other than acrylic urethane resin and olefin resin}
In one embodiment of the present invention, the composition (y) may contain a resin other than the acrylic urethane-based resin and the olefin-based resin as long as the effects of the present invention are not impaired.
Examples of such resins include vinyl resins such as polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer Polycarbonate; Polyurethane not applicable to acrylic urethane resin; Polysulfone; Polyetheretherketone; Polyethersulfone; Polyphenylene sulfide; Polyimide resin such as polyetherimide and polyimide; Polyamide resin; Acrylic resin; Fluorine resin etc. are mentioned.

However, the viewpoint of further improving the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the heat-expandable base material (Y), and when the pressure-sensitive adhesive layer (X2) is present, the heat-expandable base material (Y) From the viewpoint of further improving the interfacial adhesion with the interface between the adhesive layer and the pressure-sensitive adhesive layer (X2), the content ratio of the resin other than the acrylic urethane-based resin and the olefin-based resin in the composition (y) is preferably small.
The content of the resin other than the acrylic urethane-based resin and the olefin-based resin is preferably less than 30 parts by weight, more preferably less than 20 parts by weight with respect to 100 parts by weight of the total amount of the resin contained in the composition (y). More preferably, it is less than 10 mass parts, More preferably, it is less than 5 mass parts, More preferably, it is less than 1 mass part.

(Crosslinking agent)
In one aspect of the present invention, when the composition (y) contains an acrylic urethane resin, it is more preferable to further contain a crosslinking agent in order to crosslink the acrylic urethane resin.
As the said crosslinking agent, the isocyanate type compound as a crosslinking agent is preferable, for example.
As the isocyanate compound as the crosslinking agent, various isocyanate compounds can be used as long as they react with the functional group of the acrylic urethane resin to form a crosslinked structure.
The isocyanate compound is preferably a polyisocyanate compound having two or more isocyanate groups per molecule.

Examples of the polyisocyanate compound include diisocyanate compounds, triisocyanate compounds, tetraisocyanate compounds, pentaisocyanate compounds, hexaisocyanate compounds, and the like. More specifically, aromatic polyisocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate; dicyclohexylmethane-4,4-diisocyanate, bicycloheptane triisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene Examples thereof include alicyclic isocyanate compounds such as diisocyanate and hydrogenated xylylene diisocyanate; aliphatic isocyanate compounds such as pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate.
In addition, biuret bodies, isocyanurate bodies of these isocyanate compounds, adduct bodies that are reaction products of these isocyanate compounds with non-aromatic low-molecular active hydrogen-containing compounds such as ethylene glycol, trimethylolpropane, castor oil, etc. Modified products can also be used.

Of these isocyanate compounds, aliphatic isocyanate compounds are preferable, aliphatic diisocyanate compounds are more preferable, and pentamethylene diisocyanate, hexamethylene diisocyanate, and heptamethylene diisocyanate are still more preferable.
In the composition (y), the isocyanate compound may be used alone or in combination of two or more.

In the composition (y), the content ratio of the acrylic urethane resin and the isocyanate compound as a crosslinking agent is an isocyanate system as a crosslinking agent with respect to a total of 100 parts by mass of the acrylic urethane resin as a solid content ratio. The compound is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and still more preferably 3 to 15 parts by mass.

(catalyst)
In one embodiment of the present invention, when the composition (y) contains an acrylic urethane resin and the crosslinking agent, the composition (y) further preferably contains a catalyst together with the crosslinking agent.
As the catalyst, a metal catalyst is preferable, and a metal catalyst excluding a tin compound having a butyl group is more preferable.
Examples of the metal catalyst include a tin catalyst, a bismuth catalyst, a titanium catalyst, a vanadium catalyst, a zirconium catalyst, an aluminum catalyst, and a nickel catalyst. Among these, a tin-based catalyst or a bismuth-based catalyst is preferable, and a tin-based catalyst or a bismuth-based catalyst excluding a tin-based compound having a butyl group is more preferable.

The tin-based catalyst is an organometallic compound of tin, and includes compounds having a structure such as alkoxide, carboxylate, chelate, etc., preferably acetylacetone complex, acetylacetonate, octylic acid compound or naphthenic acid of these metals Compounds and the like.
Similarly, the bismuth catalyst, titanium catalyst, vanadium catalyst, zirconium catalyst, aluminum catalyst, or nickel catalyst is an organometallic compound of bismuth, titanium, vanadium, zirconium, aluminum, or nickel, respectively. In addition, compounds having a structure such as alkoxide, carboxylate, chelate and the like can be mentioned, and preferred examples thereof include acetylacetone complexes, acetylacetonates, octylic acid compounds and naphthenic acid compounds of these metals.

Specific examples of the metal acetylacetone complex include acetylacetone tin, acetylacetone titanium, acetylacetone vanadium, acetylacetone zirconium, acetylacetone aluminum, and acetylacetone nickel.
Specific examples of acetylacetonate include tin acetylacetonate, bismuth acetylacetonate, titanium acetylacetonate, vanadium acetylacetonate, zirconium acetylacetonate, aluminum acetylacetonate, nickel acetylacetonate and the like.
Specific examples of the octylic acid compound include bismuth 2-ethylhexylate, nickel 2-ethylhexylate, zirconium 2-ethylhexylate, tin 2-ethylhexylate and the like.
Specific examples of the naphthenic acid compound include bismuth naphthenate, nickel naphthenate, zirconium naphthenate, tin naphthenate, and the like.

As the tin-based catalyst, general formula RxSn (L) _(4-X) (wherein R is an alkyl group having 1 to 25 carbon atoms, preferably an alkyl group having 1 to 3 or 5 to 25 carbon atoms, or It is an aryl group, L is an organic group other than an alkyl group and an aryl group, or an inorganic group, and x is 1, 2 or 4).

In the general formula RxSn (L) _(4-X) , the alkyl group of R is more preferably an alkyl group having 5 to 25 carbon atoms, further preferably an alkyl group having 5 to 20 carbon atoms, and the aryl group of R is The number of carbon atoms is not particularly limited, but an aryl group having 6 to 20 carbon atoms is preferable. When two or more R are present in one molecule, each R may be the same or different.
L is preferably an aliphatic carboxylic acid, aromatic carboxylic acid or aromatic sulfonic acid having 2 to 20 carbon atoms, more preferably an aliphatic carboxylic acid having 2 to 20 carbon atoms. Examples of the aliphatic carboxylic acid having 2 to 20 carbon atoms include an aliphatic monocarboxylic acid having 2 to 20 carbon atoms and an aliphatic dicarboxylic acid having 2 to 20 carbon atoms. When two or more L are present in one molecule, each L may be the same or different.

In the composition (y), the catalyst may be used alone or in combination of two or more.
In the composition (y), the content ratio of the acrylic urethane resin and the catalyst is preferably 0.001 to 5 parts by mass in terms of solid content of the catalyst with respect to 100 parts by mass in total of the acrylic urethane resin. The amount is preferably 0.01 to 3 parts by mass, more preferably 0.1 to 2 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 additives for base materials are contained, the content of each additive for base materials is the total amount of resin selected from the group consisting of acrylurethane resins and olefin resins contained in the composition (y). The amount is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass with respect to 100 parts by mass.

(Diluted solvent)
In one embodiment of the present invention, the composition (y) may contain water or an organic solvent as a diluent solvent together with the various active ingredients described above, and may be in the form of a solution.
Examples of the organic solvent include toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, tert-butanol, s-butanol, acetylacetone, cyclohexanone, n-hexane, and cyclohexane. Etc.
In addition, these dilution solvents may be used independently and may be used in combination of 2 or more type.

When the composition (y) is in the form of a solution containing a diluting solvent, the active ingredient concentration of the composition (y) is preferably independently 0.1 to 60% by mass, more preferably 0. It is 5 to 50% by mass, more preferably 1.0 to 40% by mass.

[Adhesive layer (X1)]
The pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet of the present invention is a layer formed by drying a coating film (x1 ′) made of a composition (x1) containing a pressure-sensitive adhesive resin, and has pressure-sensitive 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.
If the said adhesive force is 0.1 N / 25mm or more, to-be-adhered bodies, such as a semiconductor chip, can fully be fixed.
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.

The composition (x1) that is a material for forming the pressure-sensitive adhesive layer (X1) contains a pressure-sensitive adhesive resin. In addition, in 1 aspect of this invention, components other than adhesive resin contained in a composition (x1) can be suitably adjusted according to the use application of the adhesive sheet of this invention.
For example, in one embodiment of the present invention, the composition (x1) may further contain a tackifier and / or a cross-linking agent from the viewpoint of obtaining a pressure-sensitive adhesive sheet with improved adhesive strength. , And / or an adhesive additive used in a diluting solvent and / or a general adhesive.
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 resin)
The mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and even more preferably 30,000 to 1,000,000 from the viewpoint of improving the adhesive strength.
Examples of the adhesive resin contained in the composition (x1) include rubber resins such as acrylic resins, urethane resins, polyisobutylene resins, polyester resins, and olefins that satisfy the adhesive force as the above-mentioned adhesive resins. Resin, silicone resin, polyvinyl ether resin and the like.
These adhesive resins may be used alone or in combination of two or more.
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.
Furthermore, from the viewpoint of further improving the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y), these pressure-sensitive adhesive resins are UV non-curable pressure-sensitive adhesives having no polymerizable functional group. A resin is preferred.

The content of the adhesive resin in the composition (x1) is preferably 30 to 99.99% by mass, more preferably 40 to 99%, based on the total amount (100% by mass) of the active ingredients of the composition (x1). .95% by mass, more preferably 50 to 99.90% by mass, still more preferably 55 to 99.80% by mass, and still more preferably 60 to 99.50% by mass.

{Acrylic resin}
In one embodiment of the present invention, from the viewpoint of further improving the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable base material (Y), the pressure-sensitive resin contained in the composition (x1) is an acrylic resin. It is preferable to contain.
The content ratio of the acrylic resin in the adhesive resin is preferably from 30 to the total amount (100% by mass) of the adhesive resin contained in the composition (x1) from the viewpoint of further improving the interfacial adhesion. The amount is 100% by mass, more preferably 50 to 100% by mass, still more preferably 70 to 100% by mass, and still more preferably 85 to 100% by mass.

Examples of acrylic resins that can be used as adhesive resins include polymers containing structural units derived from alkyl (meth) acrylates having linear or branched alkyl groups, and (meth) acrylates having a cyclic structure. Examples thereof include a polymer containing a derived structural unit.

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

As an acrylic resin used in one embodiment of the present invention, an acrylic polymer having a structural unit (a1) derived from alkyl (meth) acrylate (a1 ′) (hereinafter also referred to as “monomer (a1 ′)”). (A0) is preferred, and the acrylic copolymer having the structural unit (a2) derived from the functional group-containing monomer (a2 ′) (hereinafter also referred to as “monomer (a2 ′)”) together with the structural unit (a1). (A1) is more preferable.

The number of carbon atoms of the alkyl group contained in the monomer (a1 ′) is preferably 1 to 24, more preferably 1 to 12, still more preferably 1 to 8, and still more preferably 4 to 6 from the viewpoint of improving adhesive properties. It is.
The alkyl group contained in the monomer (a1 ′) may be a linear alkyl group or a branched alkyl group.

Examples of the monomer (a1 ′) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, tridecyl ( Examples include meth) acrylate and stearyl (meth) acrylate.
These monomers (a1 ′) may be used alone or in combination of two or more.
As the monomer (a1 ′), methyl (meth) acrylate, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable, and methyl (meth) acrylate and butyl (meth) acrylate are more preferable.

The content of the structural unit (a1) is preferably 50 to 100% by weight, more preferably based on the total structural unit (100% by weight) of the acrylic polymer (A0) or the acrylic copolymer (A1). It is 60 to 99.9% by mass, more preferably 70 to 99.5% by mass, and still more preferably 80 to 99.0% by mass.

The functional group possessed by the monomer (a2 ′) refers to a functional group capable of reacting with a crosslinking agent that may be contained in the composition (x1) described later to serve as a crosslinking starting point or a functional group having a crosslinking accelerating effect. , Carboxy group, amino group, epoxy group and the like.
That is, examples of the monomer (a2 ′) include a hydroxyl group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer.
These monomers (a2 ′) may be used alone or in combination of two or more.
As the monomer (a2 ′), a hydroxyl group-containing monomer and a carboxy group-containing monomer are preferable.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl (meth) ) And hydroxyalkyl (meth) acrylates such as 4-hydroxybutyl (meth) acrylate; and unsaturated alcohols such as vinyl alcohol and allyl alcohol.

Examples of the carboxy group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid and citraconic acid, and anhydrides thereof. 2- (acryloyloxy) ethyl succinate, 2-carboxyethyl (meth) acrylate and the like.
As the monomer (a2 ′), 2-hydroxyethyl (meth) acrylate is preferable.

The content of the structural unit (a2) is preferably 0.1 to 40% by weight, more preferably 0.3 to 30%, based on the entire structural unit (100% by weight) of the acrylic copolymer (A1). % By mass, more preferably 0.5 to 20% by mass, still more preferably 0.7 to 10% by mass.

The acrylic copolymer (A1) may further have a structural unit (a3) derived from another monomer (a3 ′) other than the monomers (a1 ′) and (a2 ′).
In the acrylic copolymer (A1), the content of the structural units (a1) and (a2) is preferably 70 with respect to the total structural units (100% by mass) of the acrylic copolymer (A1). To 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass.

As the monomer (a3 ′), for example, olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene and chloroprene; cyclohexyl (meth) acrylate, It has a cyclic structure such as benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, imide (meth) acrylate, etc. (Meth) acrylate; styrene, α-methylstyrene, vinyl toluene, vinyl formate, vinyl acetate, acrylonitrile, (meth) acrylamide, (meth) acrylonitrile, (meth) acryloyl mole Phosphorus, N- vinylpyrrolidone and the like.
As the monomer (a3 ′), vinyl acetate is preferable.

{Urethane resin}
The urethane resin that can be used as the adhesive resin is not particularly limited as long as it is a polymer having at least one of a urethane bond and a urea bond in at least one of the main chain and the side chain.
Specific examples of the urethane resin include a urethane prepolymer (UX) obtained by reacting a polyol and a polyvalent isocyanate compound.
The urethane prepolymer (UX) may be obtained by further subjecting to a chain extension reaction using a chain extender.

The mass average molecular weight (Mw) of the urethane resin is preferably 10,000 to 200,000, more preferably 12,000 to 150,000, still more preferably 15,000 to 100,000, and still more preferably 20,000 to 70,000.

Examples of the polyol used as a raw material for the urethane-based prepolymer (UX) include polyol compounds such as alkylene type polyols, polyether type polyols, polyester type polyols, polyester amide type polyols, polyester / polyether type polyols, and polycarbonate type polyols. Although it is mentioned, if it is a polyol, it will not specifically limit, Bifunctional diol and a trifunctional triol may be sufficient.
These polyols may be used alone or in combination of two or more.
Among these polyols, diols are preferable and alkylene type diols are more preferable from the viewpoints of availability, reactivity, and the like.

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.
Among these alkylene diols, glycols having a mass average molecular weight (Mw) of 1,000 to 3,000 are preferred from the viewpoint of suppressing gelation when the reaction with a chain extender is performed.

Examples of the polyvalent isocyanate compound that is a raw material for the urethane prepolymer (UX) include aromatic polyisocyanates, aliphatic polyisocyanates, and alicyclic polyisocyanates.
Examples of the aromatic polyisocyanate include 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2 , 6-Tolylene diisocyanate (2,6-TDI), 4,4′-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4 ′ -Diphenyl ether diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate, 1,4-tetramethylxylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate and the like.
Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HMDI), pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, and dodeca. Examples include methylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate.
Examples of the alicyclic polyisocyanate include 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI: isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4- Cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), 1,4-bis (isocyanatemethyl) cyclohexane, 1,4-bis (isocyanate) Methyl) cyclohexane and the like.
In addition, these polyisocyanate compounds may be a trimethylolpropane adduct modified product of the polyisocyanate, a burette modified product reacted with water, or an isocyanurate modified product containing an isocyanurate ring.

Among these polyvalent isocyanate compounds, 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate (2,4-TDI), 2, from the viewpoint of obtaining a urethane polymer having excellent adhesive properties. One or more selected from 6-tolylene diisocyanate (2,6-TDI), hexamethylene diisocyanate (HMDI), 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) and modified products thereof are preferable. From the viewpoint of weather resistance, at least one selected from HMDI, IPDI, and modified products thereof is more preferable.

The isocyanate group content (NCO%) in the urethane prepolymer (UX) is preferably 0.5 to 12% by mass, more preferably 1 to 4 in a value measured according to JIS K1603-1: 2007. % By mass.

As the chain extender, a compound having at least one of hydroxyl group and amino group, or a compound having at least three of hydroxyl group and amino group is preferable.

The compound having at least one of a hydroxyl group and an amino group is preferably at least one compound selected from the group consisting of aliphatic diols, aliphatic diamines, alkanolamines, bisphenols, and aromatic diamines.
Examples of the aliphatic diol include alkanediols such as 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, and 1,7-heptanediol. Alkylene glycols such as ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol;
Examples of the aliphatic diamine include ethylenediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, and the like.
Examples of the alkanolamine include monoethanolamine, monopropanolamine, isopropanolamine and the like.
Examples of bisphenol include bisphenol A and the like.
Examples of the aromatic diamine include diphenylmethanediamine, tolylenediamine, xylylenediamine, and the like.

Examples of the compound having at least three hydroxyl groups and amino groups include polyols such as trimethylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol; 1-amino-2,3-propanediol, 1-methyl And amino alcohols such as amino-2,3-propanediol and N- (2-hydroxypropylethanolamine); ethylene oxide or propylene oxide adducts of tetramethylxylylenediamine;

{Polyisobutylene resin}
The polyisobutylene resin (hereinafter also referred to as “PIB resin”) that can be used as an adhesive resin is not particularly limited as long as it has a polyisobutylene skeleton in at least one of a main chain and a side chain.

The mass average molecular weight (Mw) of the PIB resin is preferably 20,000 or more, more preferably 30,000 to 1,000,000, still more preferably 50,000 to 800,000, and still more preferably 70,000 to 600,000.

Examples of the PIB resin include polyisobutylene which is a homopolymer of isobutylene, a copolymer of isobutylene and isoprene, a copolymer of isobutylene and n-butene, a copolymer of isobutylene and butadiene, and these copolymers. Examples thereof include halogenated butyl rubber that has been brominated or chlorinated.

When the PIB-based resin is a copolymer, it is assumed that the structural unit composed of isobutylene is contained in the largest amount among all the structural units.
The content of the structural unit composed of isobutylene is preferably 80 to 100% by mass, more preferably 90 to 100% by mass, and still more preferably 95 to 100% by mass with respect to all the structural units (100% by mass) of the PIB resin. %.
These PIB-based resins may be used alone or in combination of two or more.

Moreover, when using PIB-type resin, it is preferable to use together PIB-type resin with a high mass average molecular weight (Mw) and PIB-type resin with a low mass average molecular weight (Mw).
More specifically, a PIB resin (p1) having a mass average molecular weight (Mw) of 270,000 to 600,000 (hereinafter also referred to as “PIB resin (p1)”), and a mass average molecular weight (Mw) of 5 It is preferable to use 10,000 to 250,000 PIB resin (p2) (hereinafter also referred to as “PIB resin (p2)”) in combination.
By using the PIB resin (p1) having a high mass average molecular weight (Mw), the durability and weather resistance of the pressure-sensitive adhesive layer to be formed can be improved, and the adhesive strength can also be improved.
Further, by using a PIB resin (p2) having a low mass average molecular weight (Mw), it can be well compatible with the PIB resin (p1), and the PIB resin (p1) can be appropriately plasticized. The wettability of the pressure-sensitive adhesive layer to the adherend can be improved, and the physical properties of adhesive, flexibility and the like can be improved.

The mass average molecular weight (Mw) of the PIB resin (p1) is preferably 270,000 to 600,000, more preferably 290,000 to 480,000, still more preferably 310,000 to 450,000, and even more preferably 320,000 to 400,000. It is.
The mass average molecular weight (Mw) of the PIB resin (p2) is preferably 50,000 to 250,000, more preferably 80,000 to 230,000, still more preferably 140,000 to 220,000, and still more preferably 180,000 to 210,000. It is.

The content ratio of the PIB resin (p2) to 100 parts by mass of the PIB resin (p1) is preferably 5 to 55 parts by mass, more preferably 6 to 40 parts by mass, still more preferably 7 to 30 parts by mass, and even more. The amount is preferably 8 to 20 parts by mass.

{Olefin resin}
The olefin resin that can be used as the adhesive resin is not particularly limited as long as it is a polymer having a structural unit derived from an olefin compound such as ethylene or propylene.
The said olefin resin may be used independently and may be used in combination of 2 or more type.
Specific examples of the olefin-based resin include polyethylenes such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene, polypropylene, copolymers of ethylene and propylene, ethylene and other α- Copolymers of olefins, copolymers of propylene and other α-olefins, copolymers of ethylene, propylene and other α-olefins, copolymers of ethylene and other ethylenically unsaturated monomers Examples thereof include ethylene (vinyl-vinyl acetate copolymer, ethylene-alkyl (meth) acrylate copolymer, etc.) and the like.
Examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, 4-methyl-1-hexene and the like.
Examples of the ethylenically unsaturated monomer include vinyl acetate, alkyl (meth) acrylate, vinyl alcohol, and the like.

(Tackifier)
In one embodiment of the present invention, it is preferable that the composition (x1) further contains a tackifier from the viewpoint of obtaining a pressure-sensitive adhesive sheet with improved adhesive strength.
Here, the “tackifier” is a component that assists in improving the adhesive strength of the adhesive resin, and refers to an oligomer having a mass average molecular weight (Mw) of less than 10,000. It is a distinction.
The weight average molecular weight (Mw) of the tackifier is preferably 400 to 10,000, more preferably 500 to 8,000, and still more preferably 800 to 5,000.

Examples of tackifiers include rosin resins such as rosin resins, rosin ester resins, and rosin-modified phenol resins; hydrogenated rosin resins obtained by hydrogenating these rosin resins; terpene resins, aromatic modified terpene resins, and terpene phenols. Terpene resins such as epoxy resins; hydrogenated terpene resins obtained by hydrogenating these terpene resins; styrene obtained by copolymerizing a styrene monomer such as α-methylstyrene or β-methylstyrene with an aliphatic monomer Hydrogenated styrene resins obtained by hydrogenating these styrene resins; C5 systems obtained by copolymerizing C5 fractions such as pentene, isoprene, piperine, 1,3-pentadiene generated by thermal decomposition of petroleum naphtha Petroleum resin and hydrogenated petroleum resin of this C5 petroleum resin; indene and vinyli produced by thermal decomposition of petroleum naphtha And C9 petroleum resins obtained by copolymerizing C9 fractions such as toluene and hydrogenated petroleum resins.
These tackifiers may be used alone or in combination of two or more different softening points and structures.

The softening point of the tackifier is preferably 60 to 170 ° C, more preferably 65 to 160 ° C, and still more preferably 70 to 150 ° C.
In the present specification, the “softening point” of the tackifier means a value measured according to JIS K2531.
Moreover, when using 2 or more types of several tackifier, it is preferable that the weighted average of the softening point of these several tackifier belongs to the said range.

The content of the tackifier in the composition (x1) is preferably 0.01 to 65% by mass, more preferably 0.00%, based on the total amount (100% by mass) of the active ingredients in the composition (x1). It is 05 to 55% by mass, more preferably 0.1 to 50% by mass, still more preferably 0.5 to 45% by mass, and still more preferably 1.0 to 40% by mass.

In addition, the total content of the adhesive resin and the tackifier in the composition (x1) is preferably 70% by mass or more, more preferably based on the total amount (100% by mass) of the active ingredients in the composition (x1). Is 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, and still more preferably 95% by mass or more.

(Crosslinking agent)
In one embodiment of the present invention, the composition (x1) further contains a crosslinking agent together with the above-mentioned pressure-sensitive adhesive resin having a functional group such as an acrylic copolymer having the structural units (a1) and (a2). It is preferable to do.
The said crosslinking agent reacts with the functional group which the said adhesive resin has, and bridge | crosslinks resin.

Examples of the cross-linking agent include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and the like, and adducts thereof; epoxy cross-linking agents such as ethylene glycol glycidyl ether; hexa [1- (2- Methyl) -aziridinyl] triphosphatriazine and other aziridine crosslinkers; aluminum chelates and other chelate crosslinkers; and the like.
These cross-linking agents may be used alone or in combination of two or more. Among these crosslinking agents, an isocyanate-based crosslinking agent is preferable from the viewpoints of increasing cohesive force and improving adhesive force, and availability.

The content of the cross-linking agent is appropriately adjusted depending on the number of functional groups of the adhesive resin. For example, with respect to 100 parts by mass of the adhesive resin having the above-described functional groups such as the acrylic copolymer. The amount is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and still more preferably 0.05 to 5 parts by mass.

(Adhesive additive)
In one aspect of the present invention, the composition (x1) contains an additive for pressure-sensitive adhesives used for general pressure-sensitive adhesives other than the above-described tackifier and cross-linking agent as long as the effects of the present invention are not impaired. You may do it.
Examples of the adhesive additive include an antioxidant, a softening agent (plasticizer), a rust inhibitor, a pigment, a dye, a retarder, a catalyst, and an ultraviolet absorber.
These pressure-sensitive adhesive additives may be used alone or in combination of two or more.
When these pressure-sensitive adhesive additives are contained, the content of each pressure-sensitive adhesive additive is preferably independently 0.0001 to 20 parts by mass, more preferably 100 parts by mass of the adhesive resin. 0.001 to 10 parts by mass.

(Diluted solvent)
In one embodiment of the present invention, the composition (x1) may contain water or an organic solvent as a diluent solvent together with the various active ingredients described above, and may be in the form of a solution.
As an organic solvent, the same thing as the organic solvent used when preparing the above-mentioned composition (y) in the form of a solution is mentioned.
In addition, the dilution solvent contained in a composition (x1) may be used independently, and may be used in combination of 2 or more type.

When the composition (x1) is in the form of a solution containing a diluting solvent, the active ingredient concentration of the composition (x1) is preferably 0.1 to 60% by mass, more preferably 0.5 to 50% by mass. %, More preferably 1.0 to 45% by mass.

[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 a composition (x2) containing a pressure-sensitive adhesive resin, and has pressure-sensitive 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): Laminate in which the coating film (x1 ′) and the coating film (y ′) are simultaneously dried, and the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) are directly laminated in this order. Forming the 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 addition, it is preferable that a composition (x1) and a composition (y) contain a dilution solvent each independently further from a viewpoint of making each coating film easy to form and improving productivity.
As a dilution solvent, the above-mentioned dilution solvent demonstrated in the column of the adhesive sheet can be used.
Moreover, the active ingredient density | concentration of the solution obtained by mix | blending a dilution solvent with each composition is as having mentioned above in the column of the adhesive sheet.

In addition, in this process (1A), after forming the coating film of 1 layer or more of a coating film (x1 ') and a coating film (y'), before the process (2A) mentioned later, the hardening reaction of the said coating film is carried out. You may give the predrying process of the grade which does not advance.
For example, a pre-drying treatment may be performed each time the coating film (x1 ′) and the coating film (y ′) are formed, and the coating film (x1 ′) and the coating film (y ′) 2 You may perform a predrying process simultaneously to the said 2 layer after forming the coating film of a layer. When pre-drying is performed, from the viewpoint of improving the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y), the coating film (x1 ′) and the coating film (y ′) 2 It is preferable to pre-dry the two layers simultaneously after forming the coating film of the layers.
In this step (1A), the drying temperature at the time of performing the pre-drying treatment is usually appropriately set within a temperature range in which the formed coating film does not cure, but preferably in step (2A). Below the drying temperature.
The specific drying temperature indicated by the phrase “below the drying temperature in step (2A)” is preferably 10 to 45 ° C., more preferably 10 to 34 ° C., and further preferably 15 to 30 ° C.

In the step (2A), the coating film (x1 ′) and the coating film (y ′) are simultaneously dried to form the laminate.
In this drying 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 ′) are separated. It is thought that the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y) is improved by drying and curing in an intertwined state.

The drying temperature of the coating film in the step (2A) is preferably 60 to 150 ° C, more preferably 70 to 145 ° C, still more preferably 80 to 140 ° C, and still more preferably 90 to 135 ° C.

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 any of the following steps (3A-1) to (3A-4) in addition to the steps (1A) and (2A) described above.
Step (3A-1): A step of heat-melting the composition (x2) containing an adhesive resin and extrusion laminating it on the surface of the thermally expandable substrate (Y) obtained in the step (2A).
Step (3A-2): Forming a coating film (x2 ′) composed of a composition (x2) containing an adhesive resin on the surface of the thermally expandable substrate (Y) obtained in step (2A) And drying the coating film (x2 ′).
Step (3A-3): The composition (x2) containing the adhesive resin is heated and melted, and the pressure-sensitive adhesive layer (X2) is prepared in advance on the release-treated surface of the release material by extrusion molding. The step of directly sticking the pressure-sensitive adhesive layer (X2) formed on the release material onto the surface of the thermally expandable substrate (Y) obtained in (1).
Step (3A-4): A composition (x2) containing an adhesive resin is applied to the release treatment surface of the release material to form a coating film (x2 ′), and the coating film (x2 ′) is dried. The pressure-sensitive adhesive layer (X2) is formed in advance, and the pressure-sensitive adhesive layer (X2) formed on the release material is directly formed on the surface of the thermally expandable substrate (Y) obtained in the step (2A). The process of sticking.

Examples of the method for forming the coating film (x2 ′) in the steps (3A-2) and (3A-4) include spin coater, spray coater, bar coater, knife coater, roll coater, knife roll coater, blade coater, and gravure coater. , Curtain coater, die coater and the like.
Moreover, from the viewpoint of facilitating the formation of the coating film (x2 ′) and improving the productivity, it is preferable that the composition (x2) further contains the aforementioned dilution solvent. Moreover, the active ingredient density | concentration of the solution obtained by mix | blending a dilution solvent with a composition (x2) is also as above-mentioned.

The drying temperature of the coating film (x2 ′) in the steps (3A-2) and (3A-4) is preferably 60 to 150 ° C., more preferably 70 to 145 ° C., still more preferably 80 to 140 ° C., and still more The temperature is preferably 90 to 135 ° C.

Among the steps (3A-1) to (3A-4), the step (3A-2) 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.
Step (2B): The coating film (x1 ′), the coating film (y ′), and the coating film (x2 ′) are simultaneously dried, and the pressure-sensitive adhesive layer (X1), the thermally expandable substrate (Y), and The process of forming the laminated body by which the adhesive layer (X2) is directly laminated | stacked 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 a coating film (x2') on the peeling process surface of a peeling material from a viewpoint of handleability.

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 addition, from the viewpoint of facilitating formation of each coating film and improving productivity, the composition (x2), the composition (y), and the composition (x1) each independently further contain a dilution solvent. Is preferred.
As a dilution solvent, the above-mentioned dilution solvent demonstrated in the column of the adhesive sheet can be used.
Moreover, the active ingredient density | concentration of the solution obtained by mix | blending a dilution solvent with each composition is as having mentioned above in the column of the adhesive sheet.

In addition, in this process (1B), after forming the coating film of 1 layer or more of a coating film (x1 '), a coating film (y'), and a coating film (x2 '), before the process (2B), You may perform the predrying process of the grade which does not advance the hardening reaction of a coating film.
For example, a pre-drying treatment may be performed each time a coating film (x1 ′), a coating film (y ′), and a coating film (x2 ′) are formed. After the two-layer coating film of the coating film (y ′) is formed, the two layers may be pre-dried simultaneously, and then the coating film (x2 ′) may be formed. When pre-drying is performed, from the viewpoint of improving the interfacial adhesion between the pressure-sensitive adhesive layer (X1) and the thermally expandable substrate (Y), the coating film (x1 ′) and the coating film (y ′) 2 It is preferable to pre-dry the two layers simultaneously after forming the coating film of the layers.
In the present step (1B), the drying temperature at the time of performing the pre-drying treatment is usually appropriately set within a temperature range in which the formed coating film does not proceed, but preferably in the step (2B). Below the drying temperature.
The specific drying temperature indicated by the phrase “below the drying temperature in step (2B)” is preferably 10 to 45 ° C., more preferably 10 to 34 ° C., and further preferably 15 to 30 ° C.

In the step (2B), the coating film (x1 ′), the coating film (y ′), and the coating film (x2 ′) are simultaneously dried to form the laminate.
In this drying 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 ′) are separated. By drying and curing in an intertwined state, 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 ′). A mixed layer is formed at the interface with the resin, and the resin in the coating film (y ′) and the adhesive resin in the coating film (x2 ′) are dried and cured in a state where they are entangled with each other. ) And the pressure-sensitive adhesive layer (X2) are considered to be improved.

The drying temperature of the coating film in the step (2B) is preferably 60 to 150 ° C, more preferably 70 to 145 ° C, still more preferably 80 to 140 ° C, and still more preferably 90 to 135 ° C.

≪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 adhesive resin, additives, thermally expandable particles, and release material used in forming each layer in the following production examples are as follows.

<Adhesive resin>
Acrylic copolymer (i): having a structural unit derived from a raw material monomer consisting of 2-ethylhexyl acrylate (2EHA) / 2-hydroxyethyl acrylate (HEA) = 80.0 / 20.0 (mass ratio), A solution containing an acrylic copolymer having a Mw of 600,000. Diluting solvent: ethyl acetate, solid content concentration: 40% by mass.
Acrylic copolymer (ii): n-butyl acrylate (BA) / methyl methacrylate (MMA) / 2-hydroxyethyl acrylate (HEA) / acrylic acid = 86.0 / 8.0 / 5.0 / 1. A solution containing an acrylic copolymer having an Mw of 600,000 having a structural unit derived from a raw material monomer consisting of 0 (mass ratio). Diluting solvent: ethyl acetate, solid content concentration: 40% by mass.
<Additives>
Isocyanate crosslinking agent (i): manufactured by Tosoh Corporation, product name “Coronate L”, solid content concentration: 75 mass%.
<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))
The isocyanate-based crosslinking agent (i) 5.0 parts by mass (solid content ratio) is blended with 100 parts by mass of the solid content of the acrylic copolymer (i), which is an adhesive resin, and diluted with toluene. It stirred uniformly and the composition (x1) of solid content concentration (active ingredient density | concentration) 25 mass% was prepared.

Production Example 2 (Preparation of composition (x2))
The isocyanate-based crosslinking agent (i) 0.8 parts by mass (solid content ratio) is blended with 100 parts by mass of the acrylic copolymer (ii), which is an adhesive resin, and diluted with toluene, It stirred uniformly and the composition (x2) of 25 mass% of solid content concentration (active ingredient density | concentration) was prepared.

Production Example 3 (Preparation of composition (y))
(1) Synthesis of urethane prepolymer In a reaction vessel under a nitrogen atmosphere, isophorone diisocyanate (IPDI) is mixed with carbonate type diol with respect to 100 parts by mass (solid content ratio) of carbonate type diol having a mass average molecular weight of 1,000. Mixing so that the equivalent ratio of hydroxyl group to isocyanate group of isophorone diisocyanate is 1/1, adding 160 parts by mass of toluene, until the isocyanate group concentration reaches the theoretical amount while stirring under a nitrogen atmosphere , And reacted at 80 ° C. for 6 hours or more.
Subsequently, a solution obtained by diluting 1.44 parts by mass (solid content ratio) of 2-hydroxyethyl methacrylate (2-HEMA) in 30 parts by mass of toluene is added, and further at 80 ° C. until the isocyanate groups at both ends disappear. The mixture was reacted for 6 hours to obtain a urethane prepolymer having a mass average molecular weight of 29,000.

(2) Synthesis of acrylic urethane-based resin In a reaction vessel under nitrogen atmosphere, 100 parts by mass (solid content ratio) of urethane prepolymer obtained in (1) above and 117 parts by mass (solid content ratio) of methyl methacrylate (MMA) 2-hydroxyethyl methacrylate (2-HEMA) 5.1 parts by mass (solid content ratio), 1-thioglycerol 1.1 parts by mass (solid content ratio), and toluene 50 parts by mass, The temperature was raised to ° C.
Further, a solution obtained by further diluting 2.2 parts by mass (solid content ratio) of radical initiator (manufactured by Nippon Finechem Co., Ltd., product name “ABN-E”) with 210 parts by mass of toluene in a reaction vessel was heated to 105 ° C. It was dripped over 4 hours, maintaining.
After completion of the dropping, the reaction was carried out at 105 ° C. for 6 hours to obtain a solution of an acrylic urethane resin having a mass average molecular weight of 105,000.

(3) Preparation of composition (y) With respect to 100 parts by mass of the solid content of the solution of the acrylic urethane resin obtained in (2) above, 6.3 parts by mass of the isocyanate-based crosslinking agent (i) (solid content ratio) ), 1.4 parts by weight (solid content ratio) of dioctyltin bis (2-ethylhexanoate) as a catalyst, and the thermally expandable particles (i) are diluted with toluene, stirred uniformly, A composition (y) having a solid content concentration (active ingredient concentration) of 30% by mass was prepared.
In addition, content of the thermally expansible particle (i) with respect to the whole quantity (100 mass%) of the active ingredient in the obtained 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 3, and Production Example 2 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) Drying treatment The formed coating film (x1 ′), coating film (y ′) and coating film (x2 ′) are simultaneously dried at a drying temperature of 125 ° C. for 60 seconds, and sequentially from the release agent layer of the heavy release film. A layered body in which the layer (X1), the layer (Y), and the layer (X2) were directly stacked was formed.
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 ′) composed of the composition (x1) prepared in Production Example 1 is formed and dried at a drying temperature of 110 ° C. for 120 seconds, and the layer (X1 ) Was formed.
Moreover, the coating film (y ') which consists of a composition (y) prepared by manufacture example 3 is formed on the release agent layer of the light release film prepared separately from the release film on layer (X1), and drying temperature It was dried at 110 ° C. for 120 seconds to form a layer (Y).
Furthermore, on the release agent layer of the light release film prepared separately, using the composition (x2) prepared in Production Example 2, a coating film (x2 ′) is formed and dried at a drying temperature of 110 ° C. for 120 seconds, Layer (X2) was formed.
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.

From Table 1, the pressure-sensitive adhesive sheets of Examples 1 and 2 have good interfacial adhesion, and further have good adhesive strength before heating, but to the extent that they cannot be measured after heating at or above the expansion start temperature. Since the adhesive force was lowered, it was proved that the film could be easily peeled with a slight force during peeling.

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

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) containing an adhesive resin, 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 laminated | stacked directly in this order, Then, a coating sheet (x1 ') and a coating film (y') are dried simultaneously, and the adhesive sheet is formed.
The pressure-sensitive adhesive sheet according to claim 1, 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 claim 1 or 2, 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 3, wherein the heat-expandable base material (Y) has a thickness of 5 to 140 µm.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the value of the probe tack 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. 6. The pressure-sensitive adhesive sheet according to any one of 5 to 5.
The laminate is
A coating film (x1 ′) comprising a composition (x1) containing an adhesive resin, 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) containing an adhesive resin, which is a material for forming the adhesive layer (X2);
The pressure-sensitive adhesive sheet according to claim 6, which is formed by directly laminating the films in this order and then simultaneously drying the coating films (x1 ′), (y ′) and (x2 ′).
The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the thermally expandable particles have an average particle diameter before expansion at 23 ° C of 3 to 100 µm.