WO2023176134A1

WO2023176134A1 - Article, method for producing article, foamable adhesive sheet, and adhesive composition

Info

Publication number: WO2023176134A1
Application number: PCT/JP2023/001532
Authority: WO
Inventors: 健太郎星; 信哉島田; 慎吾生田目; 泉長谷川; 純子小谷; 信之神田
Original assignee: 大日本印刷株式会社
Priority date: 2022-03-18
Filing date: 2023-01-19
Publication date: 2023-09-21
Also published as: JP2023137382A

Abstract

The present disclosure provides an article comprising a first member, a second member, and an adhesive member disposed between the first member and the second member, wherein: the adhesive member has at least a cured adhesive layer, and the cured adhesive layer is a foam layer containing a foam cured product of an adhesive composition containing a curable adhesive and a foaming agent; and in a cross-section parallel to the thickness direction of the foam layer, the number of bubbles where the length of the foam layer in the thickness direction is equal to or greater than the thickness of the foam layer minus 6 μm is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.

Description

Articles, methods for manufacturing articles, foamable adhesive sheets, and adhesive compositions

The present disclosure relates to an article, a method for manufacturing the same, and a foamable adhesive sheet and adhesive composition used therefor.

Adhesives for bonding members together are used in various fields, and many bonding methods are known.

For example, Patent Documents 1 to 3 disclose adhesive sheets containing a foaming agent (foamable adhesive sheets). As a method of using a foamable adhesive sheet, for example, a method is known in which a foamable adhesive sheet is placed between members, and then the foamable adhesive sheet is foamed and cured by heating to bond the members together.

It is desired that such a foamable adhesive sheet has good adhesion after foaming and curing.

Japanese Patent Application Publication No. 2000-53944 Patent No. 6223477 JP 2019-214729 Publication

The present disclosure has been made in view of the above-mentioned circumstances, and provides an article with excellent adhesiveness, a method for manufacturing the article that can improve adhesiveness, a foamable adhesive sheet, and an adhesive composition. The main purpose is

One embodiment of the present disclosure is an article having a first member, a second member, and an adhesive member disposed between the first member and the second member, wherein the adhesive member includes at least the cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent; In a parallel cross section, the number of cells whose length in the thickness direction of the foam layer is equal to or greater than the value of the thickness of the foam layer - 6 μm is 4 mm in the direction perpendicular to the thickness direction of the foam layer. Provided is an article having fewer than 7 pieces per length.

Another embodiment of the present disclosure is an article having a first member, a second member, and an adhesive member disposed between the first member and the second member, the adhesive member comprising: It has at least a cured adhesive layer, and the cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, and the thickness direction of the foam layer is In a cross section parallel to , the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. , provide goods.

Another embodiment of the present disclosure is a method for manufacturing an article using a foamable adhesive sheet having at least an adhesive layer, the adhesive layer being a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent. , arranging the foamable adhesive sheet between the first member and the second member; foaming and curing the foaming agent-containing adhesive layer of the foamable adhesive sheet to form a foam layer; and an adhesion step of adhering the second member, and the foam curing conditions in the adhesion step are set to the length of the foam layer in the thickness direction in a cross section parallel to the thickness direction of the foam layer. of the article, the number of bubbles having a value equal to or greater than the value of the thickness of the foam layer - 6 μm is set to be less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. A manufacturing method is provided.

Another embodiment of the present disclosure is a method for manufacturing an article using a foamable adhesive sheet having at least an adhesive layer, the adhesive layer being a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent. , arranging the foamable adhesive sheet between the first member and the second member; foaming and curing the foaming agent-containing adhesive layer of the foamable adhesive sheet to form a foam layer; and an adhesion step of adhering the member and the second member, and the foam curing conditions in the adhesion step are set to the length of the foam layer in the thickness direction in a cross section parallel to the thickness direction of the foam layer. Provided is a method for manufacturing an article, in which the number of bubbles having a diameter of 100 μm or more is set to be less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.

Another embodiment of the present disclosure is a foamable adhesive sheet having at least an adhesive layer, the adhesive layer being a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent; The foaming agent is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule, and the foaming adhesive sheet is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C. When the foaming agent-containing adhesive layer is foamed and cured to form a foam layer, in a cross section parallel to the thickness direction of the foam layer, the length of the foam layer in the thickness direction is the thickness of the foam layer. The present invention provides a foamable adhesive sheet in which the number of bubbles having a value of -6 μm or more is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.

Another embodiment of the present disclosure is a foamable adhesive sheet having at least an adhesive layer, the adhesive layer being a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent; The foaming agent is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule, and the foaming adhesive sheet is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C. When the foaming agent-containing adhesive layer is foamed and cured to form a foam layer, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more in a cross section parallel to the thickness direction of the foam layer. Provided is a foamable adhesive sheet in which the number of adhesive sheets is less than 7 per 4 mm in the direction perpendicular to the thickness direction of the foam layer.

Another embodiment of the present disclosure is an adhesive composition containing a curable adhesive and a foaming agent, wherein the curable adhesive is a thermosetting adhesive, and the foaming agent comprises: The adhesive composition is applied to one side of the support to a thickness of 45 μm, and the coating film of the adhesive composition is heated at ±20° C. at the maximum foaming temperature of the foaming agent for 15 μm. When the coating film is foamed and cured by heating for 1 minute to form a foam layer, in a cross section parallel to the thickness direction of the foam layer, the length in the thickness direction of the foam layer is the foam layer. Provided is an adhesive composition in which the number of bubbles having a value equal to or greater than the value of body layer thickness - 6 μm is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.

Another embodiment of the present disclosure is an adhesive composition containing a curable adhesive and a foaming agent, wherein the curable adhesive is a thermosetting adhesive, and the foaming agent comprises: The adhesive composition is applied to one side of the support to a thickness of 45 μm, and the coating film of the adhesive composition is heated at ±20° C. at the maximum foaming temperature of the foaming agent for 15 μm. When the coating film is foamed and cured by heating for minutes to form a foam layer, the length in the thickness direction of the foam layer is 100 μm or more in a cross section parallel to the thickness direction of the foam layer. The number of bubbles is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.

In the present disclosure, it is possible to provide an article with excellent adhesiveness, a method for manufacturing the article that can improve adhesiveness, a foamable adhesive sheet, and an adhesive composition.

FIG. 1 is a schematic cross-sectional view illustrating an article in the present disclosure. FIG. 1 is a schematic cross-sectional view illustrating an article in the present disclosure. FIG. 1 is a schematic cross-sectional view illustrating an article in the present disclosure. FIG. 1 is a schematic cross-sectional view illustrating an article in the present disclosure. FIG. 2 is a process diagram illustrating a method for manufacturing an article according to the present disclosure. FIG. 2 is a process diagram illustrating a method for manufacturing an article according to the present disclosure. FIG. 1 is a schematic cross-sectional view illustrating a foamable adhesive sheet in the present disclosure. FIG. 1 is a schematic cross-sectional view illustrating a foamable adhesive sheet in the present disclosure. FIG. 1 is a schematic cross-sectional view illustrating a foamable adhesive sheet in the present disclosure. FIG. 1 is a schematic cross-sectional view illustrating a foamable adhesive sheet in the present disclosure. 1 is a graph illustrating a TMA curve for a foamable adhesive sheet. FIG. 2 is a schematic cross-sectional view illustrating the state of the foamable adhesive sheet according to the present disclosure after foaming and curing. FIG. 2 is a schematic cross-sectional view illustrating the state of the foamable adhesive sheet according to the present disclosure after foaming and curing. FIG. 2 is a schematic cross-sectional view illustrating a method for testing the adhesion of a foamable adhesive sheet after foaming and curing.

Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different ways, and should not be construed as being limited to the description of the embodiments exemplified below. Further, in order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual form, but this is just an example and does not limit the interpretation of the present disclosure. It's not something you do. In addition, in this specification and each figure, the same elements as those described above with respect to the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

In this specification, when expressing a mode in which another member is placed on top of a certain member, when it is simply expressed as "above" or "below", unless otherwise specified, it means that the member is in contact with a certain member. This includes both cases in which another member is placed directly above or below a certain member, and cases in which another member is placed above or below a certain member via another member. In addition, in this specification, when expressing a mode in which another member is arranged on the surface of a certain member, when it is simply expressed as "on the surface side" or "on the surface", unless otherwise specified, This includes both a case where another member is placed directly above or directly below the member so as to be in contact with the member, and a case where another member is placed above or below a certain member via another member.

Furthermore, in this specification, the term "sheet" also includes a member called a "film." Furthermore, the term "film" also includes a member called a "sheet." Moreover, the numerical range in this specification is a range of average values.

Hereinafter, the article, the method for manufacturing the article, the foamable adhesive sheet, and the adhesive composition in the present disclosure will be described in detail.

A. Article The article in this disclosure has two embodiments. Each embodiment will be described below.

I. First Embodiment of Article A first embodiment of an article according to the present disclosure is an article having a first member, a second member, and an adhesive member disposed between the first member and the second member. The adhesive member has at least a cured adhesive layer, and the cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, In a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is equal to or greater than the thickness of the foam layer - 6 μm is determined by the number of cells in the foam layer. Less than 7 pieces per 4 mm length in the direction perpendicular to the thickness direction.

FIG. 1 is a schematic cross-sectional view showing an example of the article of this embodiment. As shown in FIG. 1, the article 100 includes a first member 20a, a second member 20b, and an adhesive member 30 disposed between the first member 20a and the second member 20b. The adhesive member 30 has a cured adhesive layer 11. The cured adhesive layer 11 is a foam layer 15 containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, and contains air bubbles 31 inside. In a cross section parallel to the thickness direction D1 of the foam layer 15 constituting the cured adhesive layer 11, the length s of the foam layer 15 in the thickness direction D1 of the bubbles 31 is equal to the thickness t of the foam layer 15. On the other hand, the number of bubbles within a predetermined range is less than or equal to a predetermined value per predetermined length L in the direction d2 perpendicular to the thickness direction d1 of the foam layer 15.

When the adhesive member has one cured adhesive layer and the cured adhesive layer is a foam layer, if there are large bubbles whose size is about the thickness of the foam layer, such bubbles In the area where , the cured adhesive layer is not in contact with the first member and the second member, or the contact area between the cured adhesive layer and the first member and the contact area between the cured adhesive layer and the second member are very large. becomes smaller. Therefore, it is thought that adhesion failures such as peeling, lifting, and cracking of the cured adhesive layer tend to occur starting from the bubbles.

On the other hand, in the article of this embodiment, when the adhesive member has one cured adhesive layer and the cured adhesive layer is a foam layer, in a cross section parallel to the thickness direction of the foam layer, The number of cells whose length in the thickness direction of the foam layer is within a predetermined range with respect to the thickness of the foam layer is less than or equal to a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer. This makes it possible to suppress poor adhesion. Therefore, it is possible to improve adhesiveness.

FIG. 2 is a schematic cross-sectional view showing another example of the article of this embodiment. In the article of this embodiment, as shown in FIG. 2, the adhesive member 30 can have a first cured adhesive layer 11a and a second cured adhesive layer 11b. The first cured adhesive layer 11a and the second cured adhesive layer 11b are respectively

foam layers

15a and 15b containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, and have air bubbles inside. Contains 31. In the cross section of the foam layer 15a constituting the first cured adhesive layer 11a in the thickness direction D1, the length s of the foam layer 15a in the thickness direction D1 of the bubbles 31 is equal to the thickness t1 of the foam layer 15a. On the other hand, the number of bubbles within a predetermined range is less than or equal to a predetermined value per predetermined length L in the direction D2 perpendicular to the thickness direction D1 of the foam layer 15a. Further, in the cross section in the thickness direction D1 of the foam layer 15b constituting the second cured adhesive layer 11b, the length s of the foam layer 15b in the thickness direction D1 of the bubbles 31 is equal to the thickness of the foam layer 15b. The number of bubbles within a predetermined range with respect to t2 is less than or equal to a predetermined value per predetermined length L in the direction D2 perpendicular to the thickness direction D1 of the foam layer 15b.

In addition, in FIG. 2, both the first cured adhesive layer 11a and the second cured adhesive layer 11b are foam layers 15a containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent. , 15b, but only one of the first cured adhesive layer 11a and the second cured adhesive layer 11b is a foam containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent. It may be a layer.

When the adhesive member has a first cured adhesive layer and a second cured adhesive layer, and the first cured adhesive layer and the second cured adhesive layer are foam layers, the size is the thickness of the foam layer. If there are large air bubbles, such as those that are present, the first cured adhesive layer may not be in contact with the first member, or the second cured adhesive layer may not be in contact with the second member in the area where such air bubbles are present. Or, the contact area between the first cured adhesive layer and the first member becomes very small, or the contact area between the second cured adhesive layer and the second member becomes very small. Therefore, it is thought that adhesion defects such as peeling, lifting, and cracking of the first cured adhesive layer and the second cured adhesive layer tend to occur starting from the bubbles.

On the other hand, in the article of this embodiment, when the adhesive member has a first cured adhesive layer and a second cured adhesive layer, the first cured adhesive layer and the second cured adhesive layer are foam layers. In the cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is within a predetermined range with respect to the thickness of the foam layer is determined by the thickness of the foam layer. Adhesion defects can be suppressed by being less than or equal to a predetermined value per predetermined length in the direction perpendicular to the width direction. Therefore, it is possible to improve adhesiveness.

In addition, in the case where the adhesive member has a first cured adhesive layer and a second cured adhesive layer, and when either the first cured adhesive layer or the second cured adhesive layer is a foam layer, similarly, It is possible to suppress adhesion defects and improve adhesion.

FIG. 3 is a schematic cross-sectional view showing another example of the article of this embodiment. In the article of this embodiment, as shown in FIG. 3, the adhesive member 30 can have a first cured adhesive layer 11a, a base material 12, and a second cured adhesive layer 11b in this order. Note that FIG. 3 is the same as FIG. 2 described above except that the base material 12 is disposed between the first cured adhesive layer 11a and the second cured adhesive layer 11b.

In addition, in FIG. 3, both the first cured adhesive layer 11a and the second cured adhesive layer 11b are foam layers 15a containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent. , 15b, but only one of the first cured adhesive layer 11a and the second cured adhesive layer 11b is a foam containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent. It may be a layer.

When the adhesive member has a first cured adhesive layer, a base material, and a second cured adhesive layer in this order, and the first cured adhesive layer and the second cured adhesive layer are foam layers, the size is foamed. If there are large bubbles that are about the thickness of the body layer, the first cured adhesive layer may not be in contact with the first member and the base material, or the second cured adhesive layer may not be in contact with the first member and the base material in the area where such bubbles are present. may not be in contact with the second member and the base material, or the contact area between the first cured adhesive layer and the first member and the base material may be very small, or the second cured adhesive layer may not be in contact with the second member and the base material. The contact area with the material becomes very small. Therefore, it is thought that adhesion defects such as peeling, lifting, and cracking of the first cured adhesive layer and the second cured adhesive layer tend to occur starting from the bubbles.

In contrast, in the article of this embodiment, when the adhesive member has the first cured adhesive layer, the base material, and the second cured adhesive layer in this order, the first cured adhesive layer and the second cured adhesive layer are foamed. In the case of a body layer, in a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is within a predetermined range with respect to the thickness of the foam layer, By being equal to or less than a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer, poor adhesion can be suppressed. Therefore, it is possible to improve adhesiveness.

In addition, when the adhesive member has a first cured adhesive layer, a base material, and a second cured adhesive layer, and when either the first cured adhesive layer or the second cured adhesive layer is a foam layer, Similarly, it is possible to suppress adhesion defects and improve adhesion.

Therefore, in the article of this embodiment, reliability and durability can be improved.

Hereinafter, each structure of the article of this embodiment will be explained.

1. Adhesive Member The adhesive member in the present disclosure is disposed between the first member and the second member, and has at least a cured adhesive layer. Further, the cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, and in a cross section parallel to the thickness direction of the foam layer, The number of cells whose length in the thickness direction of the layer is within a predetermined range with respect to the thickness of the foam layer is less than or equal to a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer. .

Further, the adhesive member only needs to have at least a cured adhesive layer, for example, it may have one cured adhesive layer, or it may have a first cured adhesive layer and a second cured adhesive layer. Alternatively, the first cured adhesive layer, the base material, and the second cured adhesive layer may be provided in this order.

When the adhesive member has a first cured adhesive layer and a second cured adhesive layer, or when it has a first cured adhesive layer, a base material, and a second cured adhesive layer in this order, the first cured adhesive layer and the second cured adhesive layer At least one of the two cured adhesive layers is the foam layer described above.

In this specification, for convenience, in the adhesive member, the cured adhesive layer located on the first member side is referred to as the first cured adhesive layer, and the cured adhesive layer located on the second member side is referred to as the second cured adhesive layer. .

Hereinafter, each structure of the adhesive member will be explained.

(1) Cured adhesive layer The cured adhesive layer in this embodiment is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, and is formed in the thickness direction of the foam layer. In a cross section parallel to The impact is below a predetermined value.

(a) Bubbles The cured adhesive layer in this embodiment is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, and has bubbles inside. In the cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is equal to or greater than the value of the thickness of the foam layer - 6 μm is Less than 7 pieces per 4 mm length in the vertical direction. Among these, the number of bubbles is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0.

Note that "cells whose length in the thickness direction of the foam layer is greater than or equal to the thickness of the foam layer - 6 μm" means that the length of the cells in the thickness direction of the foam layer is greater than or equal to the value of the thickness of the foam layer - 6 μm. Refers to bubbles with a thickness of -6 μm or more. For example, when the thickness of the foam layer is 200 μm, the number of cells whose length in the thickness direction of the foam layer is 200−6=194 (μm) or more falls within the above range. For example, when the thickness of the foam layer is 00 μm, the number of cells whose length in the thickness direction of the foam layer is 300−6=294 (μm) or more falls within the above range. .

Here, the length of the bubbles in the thickness direction of the foam layer and the number of bubbles in a cross section parallel to the thickness direction of the foam layer can be determined by, for example, observation using an optical microscope or a scanning electron microscope (SEM). It can be determined from an obtained image or from a tomogram obtained by an X-ray CT scan. X-ray CT scanning allows non-destructive, non-contact observation of air bubbles in the cross section of the foam layer. Therefore, when cutting the article to expose the cross section of the foam layer, it is possible to prevent the bubbles from collapsing. Therefore, the length of the bubbles in the thickness direction of the foam layer and the number of bubbles can be accurately determined. Among these, for example, when the first member and the second member are metal members, observation using an optical microscope or a scanning electron microscope (SEM) is preferable.

Furthermore, the number of bubbles in a cross section parallel to the thickness direction of the foam layer is the average value of the number of bubbles at three randomly selected locations.

In addition, the thickness of the foam layer is measured from a cross section in the thickness direction of the foam adhesive sheet observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM), or a scanning transmission electron microscope (STEM). This value can be taken as the average value of the thickness at 10 randomly selected locations. Note that the method for measuring the thickness of each layer can be similarly applied.

Furthermore, for the article, the thickness direction of the foam layer is perpendicular to the plane direction of the first member or the second member. Further, the direction perpendicular to the thickness direction of the foam layer is the plane direction of the first member or the second member. Note that the plane direction of the first member and the second member refers to the plane direction of the first member and the second member when viewed macroscopically.

In the foam layer, methods for suppressing bubbles whose length in the thickness direction of the foam layer is within a predetermined range include, for example, a method of adjusting the composition of the adhesive composition, and a method of foaming and curing the adhesive composition. One method is to adjust the conditions.

Methods for adjusting the composition of the adhesive composition include, for example, methods for adjusting the molecular weight of the resin component that is the main ingredient of the curable adhesive, methods for adjusting the maximum foaming temperature of the foaming agent, and methods for adjusting the maximum foaming temperature of the foaming agent. Examples include a method of adjusting the foaming ratio in , a method of adjusting the content of the blowing agent, and a method of adjusting the structure of the thermally expandable microcapsules when the blowing agent is a thermally expandable microcapsule.

In the method of adjusting the molecular weight of the resin component that is the main ingredient of the curable adhesive, for example, a thermosetting adhesive is used as the curable adhesive. In this case, during the foaming and curing process of the adhesive composition, the resin component is softened and fluidity increases. At this time, when the molecular weight of the resin component is large, the fluidity of the resin component is lower than when the molecular weight of the resin component is small. Therefore, the bubbles are less likely to grow and the bubbles are less likely to connect with each other, so the generation of large bubbles as described above tends to be suppressed. Therefore, by including a high molecular weight resin component as the main resin component of the curable adhesive, the generation of large bubbles as described above can be suppressed.

In the method of adjusting the maximum foaming temperature of a foaming agent, thermally expandable microcapsules are used as the foaming agent. In thermally expandable microcapsules, a thermally expandable agent such as a hydrocarbon is encapsulated inside a shell made of resin. Here, in thermally expandable microcapsules, when heated, the resin constituting the shell softens, and the pressure of a thermally expandable agent such as a hydrocarbon increases, causing the thermally expandable microcapsules to expand. As the shell becomes thinner due to expansion, if heating continues, the thermal expansion agent will escape from the thermally expandable microcapsules, causing the thermally expandable microcapsules to contract. Therefore, for example, if the maximum foaming temperature of the foaming agent is high, the foaming agent will shrink during the foaming and curing process of the adhesive composition, which will prevent the thickness of the foam layer (cured adhesive layer) from becoming thinner. I can do it. Thereby, it is possible to suppress the size of the bubbles from increasing relatively to the thickness of the foam layer (cured adhesive layer). Therefore, since the size of the bubbles can be made relatively small with respect to the thickness of the foam layer (cured adhesive layer), the formation of large bubbles as described above can be suppressed.

In the method of adjusting the foaming ratio at the maximum foaming temperature of the foaming agent, for example, if the foaming ratio at the maximum foaming temperature of the foaming agent is large, the thickness of the foam layer (cured adhesive layer) tends to increase. . Therefore, the size of the bubbles can be made relatively small with respect to the thickness of the foam layer (cured adhesive layer). Therefore, large bubbles as described above can be suppressed.

In the method of adjusting the content of the foaming agent, for example, when the content of the foaming agent is large, the thickness of the foam layer (cured adhesive layer) tends to increase. Therefore, the size of the bubbles can be made relatively small with respect to the thickness of the foam layer (cured adhesive layer). Therefore, large bubbles as described above can be suppressed.

In the method of adjusting the structure of thermally expandable microcapsules when the blowing agent is thermally expandable microcapsules, for example, if the shell thickness of the thermally expandable microcapsules is thick, gas permeability decreases and air bubbles tends to decrease in size. Furthermore, for example, when the shell of a thermally expandable microcapsule is crosslinked, the gas permeability tends to decrease and the size of the bubbles tends to decrease.

Examples of methods for adjusting the foaming and curing conditions of the adhesive composition include a method of adjusting the heating temperature when the foaming agent is thermally expandable microcapsules. For example, by setting the heating temperature within a predetermined range relative to the maximum foaming temperature of the foaming agent, generation of large bubbles as described above can be suppressed. Further, for example, by setting the heating temperature within a predetermined range with respect to the extrapolated maximum displacement temperature of the foamable adhesive sheet, the generation of large bubbles as described above can be suppressed. The specific heating temperature will be described in the section "B. Manufacturing method of article" below.

(b) Material of Cured Adhesive Layer The cured adhesive layer in this embodiment contains a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent.

(i) Curable Adhesive As the curable adhesive used for the cured adhesive layer in this embodiment, a curable adhesive generally used for the adhesive layer of a foamable adhesive sheet can be used. Examples of the curable adhesive include thermosetting adhesives and photocurable adhesives. Among these, thermosetting adhesives are preferred. The thermosetting adhesive can be applied even when the first member and the second member do not have transparency, such as metal members.

In addition, examples of curable adhesives include epoxy resin adhesives, acrylic resin adhesives, phenolic resin adhesives, unsaturated polyester resin adhesives, alkyd resin adhesives, urethane resin adhesives, Examples include thermosetting polyimide resin adhesives.

Among these, the curable adhesive is preferably an epoxy resin adhesive. That is, the curable adhesive preferably contains an epoxy resin and a curing agent. In general, epoxy resin adhesives have excellent mechanical strength, heat resistance, insulation, chemical resistance, etc., have low curing shrinkage, and can be used in a wide range of applications.

Hereinafter, a case where the curable adhesive is an epoxy resin adhesive will be explained by giving an example.

(i-1) Epoxy resin The epoxy resin in this embodiment is a compound that has at least one epoxy group or glycidyl group and is cured by causing a crosslinking polymerization reaction when used in combination with a curing agent. Epoxy resins also include monomers having at least one epoxy group or glycidyl group.

As the epoxy resin, an epoxy resin generally used for epoxy resin adhesives can be used.

Among these, it is preferable that the curable adhesive contains an epoxy resin having a weight average molecular weight of 900 or more and 100,000 or less. As described above, during the foaming and curing process of the adhesive composition, the epoxy resin softens and becomes more fluid. At this time, when the molecular weight of the epoxy resin is large, the fluidity of the epoxy resin is lower than when the molecular weight of the epoxy resin is small. Therefore, the bubbles are less likely to grow and the bubbles are less likely to connect with each other, so the generation of large bubbles tends to be suppressed. Therefore, by containing the high molecular weight epoxy resin, the generation of large bubbles can be suppressed.

In this case, the weight average molecular weight of the epoxy resin is, for example, 900 or more and 100,000 or less, may be 1,650 or more and 80,000 or less, or may be 3,800 or more and 60,000 or less.

Note that the weight average molecular weight of the resin component is a value in terms of polystyrene when measured by gel permeation chromatography (GPC).

In addition, among these, the curable adhesive includes a first epoxy resin having a softening temperature of 50° C. or higher and an epoxy equivalent of 5000 g/eq or lower, and a first epoxy resin having a softening temperature higher than that of the first epoxy resin. It is preferable to contain a second epoxy resin having a high weight average molecular weight of 20,000 or more. By using the first epoxy resin and the second epoxy resin in combination, the adhesion (tackiness) of the adhesive layer made of the adhesive composition can be reduced, and the slipperiness can be improved. Furthermore, blocking resistance and adhesiveness after foaming and curing can be improved.

For example, when aiming only to improve adhesiveness after foaming and curing, it is more effective to use an epoxy resin with a lower molecular weight (low epoxy equivalent) than an epoxy resin with a high molecular weight (high epoxy equivalent). However, when a low molecular weight (low epoxy equivalent) epoxy resin is used, blocking tends to occur.

On the other hand, when using a first epoxy resin with a relatively low softening temperature (relatively high crystallinity) and a low molecular weight (low epoxy equivalent), the first epoxy resin has a temperature higher than the softening temperature. At high temperatures, it rapidly melts and turns into a low-viscosity liquid. Therefore, it is easy to improve the adhesiveness after foaming and curing. On the other hand, since the first epoxy resin has relatively high crystallinity, it can suppress the occurrence of blocking compared to an epoxy resin with relatively low crystallinity or an epoxy resin without crystallinity. However, if only the first epoxy resin is used, there is a possibility that the effect of suppressing the occurrence of blocking may be insufficient, or the adhesive layer composed of the adhesive composition may have too high a stickiness (tackiness). be. Therefore, by further using a second epoxy resin that has a relatively high softening temperature (relatively low crystallinity) and a high molecular weight, it is possible to improve the effect of suppressing the occurrence of blocking and to reduce the The adhesiveness (tackiness) of the adhesive layer can be kept low.

(i-1-1) First epoxy resin The first epoxy resin has a softening temperature of 50° C. or higher and an epoxy equivalent of 5000 g/eq or lower. The first epoxy resin has a relatively low softening temperature (relatively high crystallinity) compared to the second epoxy resin described below. Since the first epoxy resin has relatively high crystallinity and low molecular weight, it is easy to improve adhesiveness and blocking resistance after foaming and curing. In addition, since the first epoxy resin has a low molecular weight, it is possible to increase the crosslinking density, and an adhesive layer with good mechanical strength, chemical resistance, and curability can be obtained. Moreover, it is preferable that the first epoxy resin is an epoxy resin that is solid at room temperature (23° C.).

The softening temperature of the first epoxy resin is usually 50°C or higher, may be 55°C or higher, or may be 60°C or higher. On the other hand, the softening temperature of the first epoxy resin is, for example, 150° C. or lower. The softening temperature can be measured by the ring and ball method in accordance with JIS K7234.

The epoxy equivalent of the first epoxy resin is, for example, 5000 g/eq or less, may be 3000 g/eq or less, may be 1000 g/eq or less, or may be 600 g/eq or less. On the other hand, the epoxy equivalent of the first epoxy resin is, for example, 90 g/eq or more, may be 100 g/eq or more, or may be 110 g/eq or more. Epoxy equivalent can be measured by a method based on JIS K7236 corresponding to ISO 3001 (Plastics Epoxy compounds-Determination of epoxy equivalent), and is the number of grams of resin containing 1 gram equivalent of epoxy groups.

The first epoxy resin may be a monofunctional epoxy resin, a bifunctional epoxy resin, a trifunctional epoxy resin, or a tetrafunctional or higher functional epoxy resin. .

Further, the weight average molecular weight (Mw) of the first epoxy resin is usually smaller than the weight average molecular weight (Mw) of the second epoxy resin described below. The Mw of the first epoxy resin is, for example, 6,000 or less, may be 4,000 or less, or may be 3,000 or less. On the other hand, the Mw of the first epoxy resin is, for example, 400 or more.

The first epoxy resin has a melt viscosity at 150°C of, for example, 0.005 Pa·s or more, may be 0.015 Pa·s or more, may be 0.03 Pa·s or more, and may be 0.05 Pa·s or more. - It may be s or more, and may be 0.1 Pa·s or more. If the melt viscosity is too low, good foamability may not be obtained. Additionally, if the melt viscosity of the first epoxy resin is too low (if the crystallinity of the first epoxy resin is too high), the adhesive layer composed of the adhesive composition may have high stickiness (tackiness). be. The reason is that if the melt viscosity of the first epoxy resin is too low (if the crystallinity of the first epoxy resin is too high), its crystallinity will be greatly reduced when it is compatible with the second epoxy resin or acrylic resin. This is presumed to be due to a decrease in the Tg of the adhesive layer. On the other hand, the first epoxy resin has a melt viscosity at 150°C of, for example, 10 Pa·s or less, may be 5 Pa·s or less, or may be 2 Pa·s or less. If the melt viscosity is too high, the uniformity of the adhesive layer made of the adhesive composition may deteriorate. Melt viscosity is measured in accordance with JIS K6862, which corresponds to ISO 2555 (Resins in the liquid state or as emulsions or dispersions Determination of Brookfield RV viscosity), using a Brookfield type single cylinder rotational viscometer and for heating the solution. It can be determined by measuring using a thermocell.

Next, the structure of the first epoxy resin will be explained. Examples of the first epoxy resin include aromatic epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins. Specific examples of the first epoxy resin include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin, bisphenol A novolac type epoxy resin, novolac type epoxy resin such as cresol novolac type epoxy resin, and urethane modified epoxy resin. Examples include modified epoxy resins such as resins and rubber-modified epoxy resins. In addition, other specific examples include biphenyl-type epoxy resin, stilbene-type epoxy resin, triphenolmethane-type epoxy resin, alkyl-modified triphenolmethane-type epoxy resin, triazine nucleus-containing epoxy resin, dicyclopentadiene-modified phenol-type epoxy resin, Examples include naphthalene type epoxy resin, glycol type epoxy resin, and pentaerythritol type epoxy resin. The number of first epoxy resins may be one, or two or more.

The bisphenol A epoxy resin can exist in a liquid state at room temperature or in a solid state at room temperature, depending on the number of repeating units in the bisphenol skeleton. A bisphenol A type epoxy resin whose main chain has a bisphenol skeleton of, for example, 2 or more and 10 or less is solid at room temperature. Particularly, bisphenol A type epoxy resin is preferable since it can improve heat resistance.

In particular, it is preferable that the first epoxy resin is a bisphenol A novolak type epoxy resin represented by the following general formula (1).

In general formula (1), R ¹ is a group represented by C _m H _2m (m is 1 or more and 3 or less), and R ² and R ³ are each independently C _p H _2p+1 (p is 1 or more and 3 or less), and n is 0 or more and 10 or less.

In general formula (1), m in R ¹ is preferably 1, that is, R ¹ is -CH ₂ -. Similarly, it is preferred that p in R ² and R ³ is 1, ie, R ² and R ³ are -CH ₃ . Moreover, the hydrogen bonded to the benzene ring in general formula (1) may be substituted with another element or another group.

(i-1-2) Second epoxy resin The second epoxy resin has a softening temperature higher than that of the first epoxy resin, and a weight average molecular weight of 20,000 or more. The second epoxy resin has a relatively high softening temperature (relatively low crystallinity) compared to the first epoxy resin described above. Since the second epoxy resin has relatively low crystallinity and high molecular weight, it is easy to improve blocking resistance. Furthermore, since the second epoxy resin has relatively low crystallinity and high molecular weight, it can suppress the increase in stickiness (tackiness) caused by the first epoxy resin. Moreover, it is preferable that the second epoxy resin is an epoxy resin that is solid at room temperature (23° C.).

The weight average molecular weight (Mw) of the second epoxy resin is usually larger than the weight average molecular weight (Mw) of the first epoxy resin. The Mw of the second epoxy resin is usually 20,000 or more, may be 30,000 or more, or may be 35,000 or more. On the other hand, the Mw of the second epoxy resin is, for example, 100,000 or less.

The epoxy equivalent of the second epoxy resin may be larger, smaller, or the same as the epoxy equivalent of the first epoxy resin. The epoxy equivalent of the second epoxy resin is, for example, 4000 g/eq or more, may be 5000 g/eq or more, or may be 6000 g/eq or more. On the other hand, the epoxy equivalent of the second epoxy resin is, for example, 20,000 g/eq or less.

The second epoxy resin may be a monofunctional epoxy resin, a bifunctional epoxy resin, a trifunctional epoxy resin, or a tetrafunctional or higher functional epoxy resin. .

The softening temperature of the second epoxy resin is usually higher than that of the first epoxy resin. The difference between the two may be, for example, 10°C or more, 20°C or more, or 30°C or more. The softening temperature of the second epoxy resin is, for example, 80°C or higher, and may be 90°C or higher. On the other hand, the softening temperature of the second epoxy resin is, for example, 180° C. or lower.

The structure of the second epoxy resin is the same as the structure of the first epoxy resin described above, so a description thereof will be omitted here.

(i-2) Acrylic resin When the curable adhesive is an epoxy resin adhesive, the adhesive composition may further contain an acrylic resin that is compatible with the epoxy resin. Acrylic resin is a resin that is compatible with epoxy resin. Since acrylic resin is compatible with epoxy resin, it tends to improve the toughness of the adhesive layer made of the adhesive composition. As a result, the adhesiveness after foaming and curing can be improved. Furthermore, the acrylic resin acts as a compatibilizer for the foaming agent (for example, a foaming agent whose shell is made of acrylonitrile copolymer resin), and is thought to improve adhesiveness after foaming and curing by uniformly dispersing and foaming. . In addition, the flexibility of the acrylic resin is exhibited, and it is possible to improve the adhesion to the base material after foaming and hardening and the cracking resistance after foaming and hardening. Furthermore, since the acrylic resin is compatible with the epoxy resin, the hardness of the surface of the adhesive layer can be maintained high. On the other hand, if the acrylic resin is incompatible with the epoxy resin, a flexible portion will be formed on the surface of the adhesive layer, making the interface with the first member and the second member less slippery, which may reduce workability. be.

The acrylic resin in this embodiment is compatible with the epoxy resin. Here, the fact that the acrylic resin is compatible with the epoxy resin can be confirmed, for example, by observing a cross section of the adhesive layer made of the adhesive composition using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). In some cases, this can be confirmed by the fact that micron-sized islands are not occurring. More specifically, it is preferable that the average particle size of the islands is 1 μm or less. Among these, the average particle size of the islands may be 0.5 μm or less, or 0.3 μm or less. The number of samples is preferably large, for example 100 or more. The area to be observed is in the range of 100 μm×100 μm, or in the case where the thickness of the adhesive layer is 100 μm or less, the area is in the range of thickness×100 μm.

The weight average molecular weight (Mw) of the acrylic resin is, for example, 50,000 or more, may be 70,000 or more, or may be 100,000 or more. The first epoxy resin has relatively high crystallinity, and its melt viscosity (or dynamic viscoelasticity) during heating becomes too low, and the adhesive composition is difficult to form when curing after foaming (after the foaming agent has finished foaming). However, by using an acrylic resin with a certain molecular weight, the melt viscosity can be prevented from becoming too low, and shrinkage can occur during curing after foaming. It becomes difficult to wake up. On the other hand, the Mw of the acrylic resin is, for example, 1,500,000 or less. The weight average molecular weight of the acrylic resin can be measured by GPC (eluent: THF, standard substance: PS, sample: 20 μL, flow rate: 1 mL/min, column temperature: 40° C.).

The glass transition temperature (Tg) of the acrylic resin is, for example, 90°C or higher, and may be 100°C or higher. On the other hand, the Tg of the acrylic resin is, for example, 180° C. or lower. Tg is based on JIS K7121 corresponding to ISO 3146, and can be measured by thermal analysis using a differential scanning calorimeter (DSC) or the like.

The acrylic resin may have a storage modulus (E') of 1×10 ⁶ Pa or less at the foaming start temperature. A low E' at the start of foaming improves fluidity and provides good foamability. On the other hand, E' at the foaming start temperature is, for example, 1×10 ⁵ Pa or more. Note that the foaming start temperature varies depending on the type of foaming agent. Furthermore, when two or more types of foaming agents are used as the foaming agent, the starting temperature of the main foaming reaction is defined as the foaming starting temperature.

The acrylic resin may have a storage modulus (E') of 1×10 ⁵ Pa or more at the curing start temperature. As mentioned above, shrinkage may occur during curing after foaming (from the end of foaming of the foaming agent until the adhesive composition hardens), but due to the large E' at the curing start temperature, shrinkage may occur. , shrinkage can be suppressed and good shape retention can be obtained. Note that the curing start temperature varies depending on the type of curing agent. Furthermore, when two or more types of curing agents are used as the curing agent, the starting temperature of the main curing reaction is defined as the curing starting temperature.

Further, the acrylic resin may have an average storage modulus (E') of 1×10 ⁶ Pa or more at 0° C. or higher and 100° C. or lower. By having a high average value of E' before foaming, good non-stick properties and anti-blocking properties can be obtained. On the other hand, the average value of the storage elastic modulus (E') at 0° C. or higher and 100° C. or lower is, for example, 1×10 ⁸ Pa or lower.

The acrylic resin may have a polar group. Examples of the polar group include an epoxy group, a hydroxyl group, a carboxyl group, a nitrile group, and an amide group.

The acrylic resin is a homopolymer of acrylic ester monomers, may be a mixed component containing two or more of the above homopolymers, or is a copolymer of two or more acrylic ester monomers. , or a copolymer. Moreover, the acrylic resin may be a mixed component of the above-mentioned homopolymer and the above-mentioned copolymer. The acrylic acid ester monomer "acrylic acid" also includes the concept of methacrylic acid. Specifically, the acrylic resin may be a mixture of a methacrylate polymer and an acrylate polymer, or may be an acrylic acid ester polymer such as acrylate-acrylate, methacrylate-methacrylate, or methacrylate-acrylate. . Among these, the acrylic resin preferably contains a copolymer of two or more types of acrylic ester monomers ((meth)acrylic ester copolymer).

Examples of the monomer components constituting the (meth)acrylic acid ester copolymer include the monomer components described in JP-A-2014-065889. The monomer component may have the above-mentioned polar group. Examples of the (meth)acrylic acid ester copolymer include ethyl acrylate-butyl acrylate-acrylonitrile copolymer, ethyl acrylate-acrylonitrile copolymer, and butyl acrylate-acrylonitrile copolymer. Note that "acrylic acid" such as methyl acrylate and ethyl acrylate also includes "methacrylic acid" such as methyl methacrylate and ethyl methacrylate.

The above (meth)acrylic acid ester copolymer is preferably a block copolymer, and more preferably an acrylic block copolymer such as a methacrylate-acrylate copolymer. Examples of the (meth)acrylate constituting the acrylic block copolymer include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, and acrylic acid. Examples include benzidyl. These "acrylic acids" also include "methacrylic acids."

Specific examples of the methacrylate-acrylate copolymer include acrylic copolymers such as methyl methacrylate-butyl acrylate-methyl methacrylate (MMA-BA-MMA) copolymer. MMA-BA-MMA copolymers also include block copolymers of polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate (PMMA-PBA-PMMA).

The acrylic copolymer does not need to have a polar group, or may be a modified product in which the above-mentioned polar groups are partially introduced. Since the above-mentioned modified product is easily compatible with the epoxy resin, the adhesiveness is further improved.

Among them, the acrylic resin is a (meth)acrylic acid having a first polymer part having a glass transition temperature (Tg) of 10°C or lower and a second polymer part having a glass transition temperature (Tg) of 20°C or higher. Preferably, it is an ester copolymer. Such a (meth)acrylic acid ester copolymer has a first polymer portion that becomes a soft segment and a second polymer portion that becomes a hard segment.

The manifestation of the above effects can be estimated as follows. By using an acrylic resin that has both soft and hard segments, such as the above-mentioned (meth)acrylic acid ester copolymer, the hard segments contribute to heat resistance, and the soft segments contribute to toughness or flexibility. , an adhesive layer with good heat resistance, toughness, and flexibility can be obtained.

At least one of the first polymer portion and the second polymer portion contained in the (meth)acrylic acid ester copolymer has compatibility with the epoxy resin. If the first polymer portion is compatible with the epoxy resin, flexibility can be increased. Moreover, when the second polymeric part has compatibility with the epoxy resin, cohesiveness and toughness can be improved.

If either the first polymer portion or the second polymer portion is not compatible with the epoxy resin, the (meth)acrylic acid ester copolymer is a polymer portion that is compatible with the epoxy resin. It has a certain compatible part and an incompatible part which is a polymer part that has no compatibility with the epoxy resin. In this case, when the (meth)acrylic acid ester copolymer is added, the compatible sites become compatible with the epoxy resin, and the incompatible sites are not compatible with the epoxy resin, resulting in fine phase separation. As a result, a fine sea-island structure appears. The sea-island structure depends on the type of (meth)acrylic ester copolymer, the compatibility of the first polymer part and the second polymer part contained in the (meth)acrylic ester copolymer, and the degree of modification by polar group introduction. For example, a sea-island structure where the cured epoxy resin and (meth)acrylic ester copolymer are compatible with the sea, and the (meth)acrylic ester copolymer is incompatible with the islands. A sea-island structure in which the incompatible parts of the (meth)acrylic ester copolymer are oceans, and the compatible parts of the cured epoxy resin and (meth)acrylic ester copolymer are islands, (meth) An example is a sea-island structure in which the acrylic ester copolymer is the sea and the cured epoxy resin is the island. By having such a sea-island structure, stress can be easily dispersed, so interfacial destruction can be avoided, and excellent adhesiveness can be obtained after foaming and curing.

The above-mentioned (meth)acrylic acid ester copolymer is preferably a block copolymer, particularly ABA in which the compatible portion is polymer block A and the incompatible portion is polymer block B. Preferably, it is a block copolymer. Furthermore, the first polymer portion is an incompatible portion, the second polymer portion is a compatible portion, the first polymer portion is a polymer block B, and the second polymer portion is a polymer block A. -BA block copolymer is preferred. By using such an ABA block copolymer as the acrylic resin, the compatible sites of the cured epoxy resin and the (meth)acrylic ester copolymer are In the case of a sea-island structure in which the incompatible part of the merging is an island, the island portion can be made small. In addition, in the case of a sea-island structure where the incompatible parts of the (meth)acrylic ester copolymer are oceans and the compatible parts of the cured epoxy resin and (meth)acrylic ester copolymer are islands, In the case of a sea-island structure in which the (meth)acrylic acid ester copolymer is a sea and the cured epoxy resin is an island, the sea portion can be made small.

Moreover, the above-mentioned (meth)acrylic acid ester copolymer may be a modified product in which the above-mentioned polar group is introduced into a part of the first polymer portion or the second polymer portion.

The Tg of the first polymer portion contained in the above (meth)acrylic acid ester copolymer is 10°C or less, within the range of -150°C or more and 10°C or less, especially -130°C or more and 0°C or less. It can be within a range, particularly within a range of -110°C or higher and -10°C or lower.

The Tg of the first polymer portion is calculated using the following formula based on the Tg (K) of each homopolymer described in "POLYMER HANDBOOK 3rd Edition" (published by John Wiley & Sons, Inc.). You can ask for it.
1/Tg(K)=W ₁ /Tg ₁ +W ₂ /Tg ₂ +...+W _n /Tg _n
W _n ; Mass fraction of each monomer Tg _n ; Tg (K) of the homopolymer of each monomer, as described in Polymer Handbook (3rd Ed., J. Brandrup and E.H. Immergut, WILEY INTERSCIENCE) It is sufficient to use published values that are publicly available, such as the values inside. The same applies to the Tg of the second polymer portion described below.

The first polymer portion contained in the (meth)acrylic acid ester copolymer may be a homopolymer or a copolymer, but is preferably a homopolymer. The monomer components and polymer components constituting the first polymer portion may be monomer components and polymer components that can obtain a first polymer portion having a Tg within a predetermined range, such as acrylic Acrylic acid ester monomers such as butyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, methyl acrylate, other monomers such as vinyl acetate, acetal, urethane, and polar group-containing monomers containing the above polar groups. copolymers such as EVA and EVA.

The Tg of the second polymer portion contained in the above (meth)acrylic acid ester copolymer is 20°C or higher, within the range of 20°C or higher and 150°C or lower, particularly within the range of 30°C or higher and 150°C or lower. , especially within the range of 40°C or higher and 150°C or lower.

Further, the second polymer portion contained in the above (meth)acrylic acid ester copolymer may be a homopolymer or a copolymer, but a homopolymer is particularly preferable. . The monomer component constituting the second polymer part may be any monomer component that can obtain a second polymer part having a Tg within a predetermined range, such as an acrylic ester monomer such as methyl methacrylate. other monomers such as acrylamide, styrene, vinyl chloride, amide, acrylonitrile, cellulose acetate, phenol, urethane, vinylidene chloride, methylene chloride, methacrylonitrile, and polar group-containing monomers containing the above-mentioned polar groups. One example is the body.

A specific example of the (meth)acrylic acid ester copolymer having the first polymer portion and the second polymer portion is the MMA-BA-MMA copolymer described above.

(i-3) Curing agent As the curing agent in this embodiment, a curing agent generally used for epoxy resin adhesives can be used. The curing agent is preferably solid at room temperature (23°C). A hardening agent that is solid at room temperature can have a longer storage stability (pot life) than a hardening agent that is liquid at room temperature. Further, the curing agent may be a latent curing agent. Further, the curing agent may be a curing agent that causes a curing reaction due to heat, or may be a curing agent that causes a curing reaction due to light. Moreover, a curing agent may be used alone or two or more types may be used.

The reaction initiation temperature of the curing agent is, for example, 110°C or higher, and may be 130°C or higher. If the reaction initiation temperature is too low, the reaction will start early, and curing will occur with the resin component having low flexibility and fluidity, making it difficult to achieve uniform curing. On the other hand, the reaction initiation temperature of the curing agent is, for example, 200° C. or lower. If the reaction initiation temperature is too high, the resin component may deteriorate. In addition, when using a resin with high heat resistance, such as a phenol resin, in addition to the epoxy resin, the reaction initiation temperature of the curing agent may be, for example, 300 ° C. or lower, since the resin component is less likely to deteriorate. . The reaction initiation temperature of the curing agent can be determined by differential scanning calorimetry (DSC).

Specific examples of the curing agent include imidazole curing agents, phenol curing agents, amine curing agents, acid anhydride curing agents, isocyanate curing agents, and thiol curing agents.

Examples of imidazole curing agents include imidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl Examples include -4-methylimidazole, 2-isopropylimidazole, 2-phenylimidazole, carboxylates of imidazole compounds, and adducts with epoxy compounds. Further, the imidazole curing agent preferably has a hydroxyl group. Since crystallization occurs due to hydrogen bonds between hydroxy groups, the reaction initiation temperature tends to be high.

Examples of phenolic curing agents include phenolic resins. Further, examples of the phenol resin include resol type phenol resin and novolak type phenol resin. From the viewpoint of adhesion to the substrate after foaming and curing, cracking resistance after foaming and curing, etc., a phenolic novolac resin having a Tg of 110° C. or less is particularly preferred. Furthermore, a phenolic curing agent and an imidazole curing agent may be used in combination. In that case, it is preferable to use an imidazole curing agent as a curing catalyst.

Examples of the amine curing agent include aliphatic amines such as diethylenetriamine (DETA), triethylenetetramine (TETA), and metaxylylene diamine (MXDA); diaminodiphenylmethane (DDM), m-phenylenediamine (MPDA), and diamino Examples include aromatic amines such as diphenylsulfone (DDS); alicyclic amines; and polyamide amines. Further, as the amine curing agent, a dicyandiamide curing agent such as dicyandiamide (DICY), an organic acid dihydrazide curing agent, an amine adduct curing agent, or a ketimine curing agent can be used.

Examples of acid anhydride curing agents include alicyclic acid anhydrides (liquid acid anhydrides) such as hexahydrophthalic anhydride (HHPA) and methyltetrahydrophthalic anhydride (MTHPA); trimellitic anhydride (TMA); Examples include aromatic acid anhydrides such as pyromellitic anhydride (PMDA) and benzophenonetetracarboxylic acid (BTDA).

Examples of the isocyanate curing agent include block isocyanate.

Examples of the thiol curing agent include ester bond type thiol compounds, aliphatic ether bond type thiol compounds, and aromatic ether bond type thiol compounds.

(ii) Foaming agent As the foaming agent used in the cured adhesive layer in this embodiment, a foaming agent generally used in the adhesive layer of a foamable adhesive sheet can be used. Further, the foaming agent may be a foaming agent that causes a foaming reaction due to heat, or may be a foaming agent that causes a foaming reaction due to light.

Examples of the foaming agent include thermally expandable microcapsules. It is preferable that the thermally expandable microcapsules have a core made of a thermal expansion agent such as a hydrocarbon and a shell made of a resin such as an acrylonitrile copolymer.

Furthermore, as the blowing agent, for example, an organic blowing agent or an inorganic blowing agent may be used. Examples of organic blowing agents include azo blowing agents such as azodicarbonamide (ADCA), azobisformamide, and azobisisobutyronitrile, fluorinated alkane blowing agents such as trichloromonofluoromethane, and paratoluenesulfonyl hydrazide. Hydrazine blowing agents, semicarbazide blowing agents such as p-toluenesulfonyl semicarbazide, triazole blowing agents such as 5-morpholyl-1,2,3,4-thiatriazole, N, such as N,N-dinitrosoterephthalamide, etc. - Examples include nitroso blowing agents. On the other hand, examples of inorganic blowing agents include ammonium carbonate, ammonium hydrogen carbonate, ammonium nitrite, ammonium borohydride, and azides.

The foaming initiation temperature of the foaming agent must be equal to or higher than the softening temperature of the main ingredient of a curable adhesive such as an epoxy resin, and below the activation temperature of the curing reaction of the main ingredient of a curable adhesive such as an epoxy resin. is preferred. The foaming start temperature of the foaming agent is, for example, 70°C or higher, and may be 100°C or higher. If the reaction initiation temperature is too low, foaming will start early, foaming will occur while the flexibility and fluidity of the resin component is low, and uniform foaming may be difficult to produce. On the other hand, the foaming start temperature of the foaming agent is, for example, 210° C. or lower. If the foaming start temperature is too high, the resin component may deteriorate.

Note that the softening temperature of the main ingredient of a curable adhesive such as an epoxy resin can be measured using the ring and ball softening temperature test method specified in JIS K7234.

Furthermore, as described below, when the foaming agent is a thermally expandable microcapsule, the maximum foaming temperature of the foaming agent is preferably higher than the glass transition temperature of the main ingredient of a curable adhesive such as an epoxy resin. The maximum foaming temperature of the foaming agent is, for example, preferably 140°C or more and 230°C or less, more preferably 150°C or more and 220°C or less, and even more preferably 160°C or more and 210°C or less. . If the maximum foaming temperature is too low, the foaming agent will shrink, making it impossible to maintain the thickness of the cured adhesive layer, which may reduce adhesive strength. On the other hand, if the maximum foaming temperature is too high, the expansion of the foaming agent will be insufficient and the adhesive strength may decrease.

Here, the foaming start temperature and maximum foaming temperature of the foaming agent can be determined by thermomechanical analysis (TMA). Specifically, when measured by thermomechanical analysis (TMA) at a heating rate of 20°C/min and a load force of 0.06N, the maximum displacement is The temperature indicated by the amount is defined as the maximum foaming temperature, and the temperature at 3% displacement with respect to the maximum displacement is defined as the foaming start temperature.

The average particle diameter of the blowing agent may be, for example, 10 μm or more, 13 μm or more, or 17 μm or more. Further, the average particle size of the foaming agent is preferably equal to or less than the thickness of the adhesive layer of the foamable adhesive sheet, and may be, for example, 44 μm or less, 30 μm or less, or 24 μm or less. Good too.

Note that the average particle size of the blowing agent is the particle size at 50% of the integrated value in the particle size distribution determined by laser diffraction scattering method. Furthermore, when measuring the average particle size of the foaming agent, the adhesive composition is dissolved in a solvent and the foaming agent is separated. The solvent is not particularly limited as long as it is capable of dissolving components other than the foaming agent contained in the adhesive composition, and is appropriately selected depending on the type of curable adhesive. Any solvent used in formulations can be used. Specifically, methyl ethyl ketone, ethyl acetate, toluene, etc. can be used.

The foaming ratio of the foaming agent at the maximum foaming temperature is, for example, 1.5 times or more, and may be 2 times or more. On the other hand, the foaming ratio of the foaming agent at the maximum foaming temperature is, for example, 15 times or less, and may be 10 times or less. Note that the foaming ratio of the foaming agent is the ratio of the diameter of the foaming agent after foaming to the diameter of the foaming agent before foaming.

(iii) Other components When the curable adhesive is an epoxy resin adhesive, for example, the adhesive composition used for the cured adhesive layer in this embodiment contains only an epoxy resin and an acrylic resin as resin components. or may further contain other resins. Examples of other resins include urethane resins.

The adhesive composition may contain additives such as silane coupling agents, fillers, antioxidants, light stabilizers, ultraviolet absorbers, lubricants, plasticizers, antistatic agents, crosslinking agents, colorants, etc., as necessary. may contain. Examples of the silane coupling agent include epoxy-based silane coupling agents. Examples of the filler include inorganic fillers such as calcium carbonate, aluminum hydroxide, magnesium hydroxide, antimony trioxide, zinc borate, molybdenum compounds, and titanium dioxide. Examples of the antioxidant include phenolic antioxidants and sulfur-based antioxidants.

(c) Other aspects of the cured adhesive layer The thickness of the cured adhesive layer is not particularly limited, and is appropriately set depending on the application. The thickness of the cured adhesive layer may be, for example, 30 μm or more and 1000 μm or less, 40 μm or more and 900 μm or less, or 50 μm or more and 800 μm or less. If the cured adhesive layer is too thin, sufficient adhesion may not be obtained. Furthermore, if the cured adhesive layer is too thick, the surface quality may deteriorate.

The cured adhesive layer may be a continuous layer or a discontinuous layer.

The cured adhesive layer contains a foamed cured product of the adhesive composition. Examples of methods for foaming and curing the adhesive composition include heating and light irradiation. Among these, it is preferable to foam and harden the adhesive composition by heating. The heating method is applicable even when the first member and the second member do not have transparency, such as metal members.

(d) First cured adhesive layer and second cured adhesive layer In this embodiment, when the adhesive member has a first cured adhesive layer and a second cured adhesive layer, or when the first cured adhesive layer and the base material and a second cured adhesive layer in this order, at least one of the first cured adhesive layer and the second cured adhesive layer contains a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent. All you have to do is stay there. For example, one of the first cured adhesive layer and the second cured adhesive layer contains a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, and the other contains a curable adhesive. and may contain a cured product of an adhesive composition that does not contain a foaming agent, and both the first cured adhesive layer and the second cured adhesive layer contain a curable adhesive and a foaming agent. It may also contain a foamed cured product of the adhesive composition. Among these, it is preferable that both the first cured adhesive layer and the second cured adhesive layer contain a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent. Adhesion can be improved. Furthermore, when manufacturing articles using the foamable adhesive sheet, the insertability of the foamable adhesive sheet can be improved.

(2) Base material The adhesive member in this embodiment may have a base material between the first cured adhesive layer and the second cured adhesive layer. When a base material is arranged between the first cured adhesive layer and the second cured adhesive layer, when manufacturing an article using the foamable adhesive sheet, the handling and workability of the foamable adhesive sheet can be improved. You can make it better. On the other hand, when a base material is not placed between the first cured adhesive layer and the second cured adhesive layer, when manufacturing an article using a foamable adhesive sheet, the thickness of the entire foamable adhesive sheet is It can be made thinner, and the foam adhesive sheet can be inserted into narrow gaps.

It is preferable that the base material has insulation properties. Further, the base material is preferably in the form of a sheet. The base material may have a single layer structure or a multilayer structure. Further, the base material may or may not have a porous structure inside.

Examples of the base material include resin base materials and nonwoven fabrics.

Examples of the resin contained in the resin base material include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate (PEN), and aromatic polyester; polycarbonate; polyarylate; polyurethane; polyamide, polyether amide, etc. polyamide resins; polyimide resins such as polyimide, polyetherimide, and polyamideimide; polysulfone resins such as polysulfone and polyethersulfone; polyetherketone resins such as polyetherketone and polyetheretherketone; polyphenylene sulfide (PPS); modified polyphenylene Examples include oxides. The glass transition temperature of the resin is, for example, 80°C or higher, may be 140°C or higher, or may be 200°C or higher. Furthermore, liquid crystal polymer (LCP) may be used as the resin.

Examples of the nonwoven fabric include nonwoven fabrics containing fibers such as cellulose fibers, polyester fibers, nylon fibers, aramid fibers, polyphenylene sulfide fibers, liquid crystal polymer fibers, glass fibers, metal fibers, and carbon fibers.

The base material may be subjected to surface treatment in order to improve the adhesion with the first cured adhesive layer and the second cured adhesive layer.

The thickness of the base material is not particularly limited, but may be, for example, 2 μm or more and 200 μm or less, 5 μm or more and 100 μm or less, or 9 μm or more and 50 μm or less.

(3) Other configurations The adhesive member in this embodiment may have a first intermediate layer between the base material and the first cured adhesive layer. Moreover, the adhesive member in this embodiment may have a second intermediate layer between the base material and the second cured adhesive layer. By arranging the first intermediate layer and the second intermediate layer, it is possible to improve the adhesion of the first cured adhesive layer and the second cured adhesive layer to the base material. Furthermore, when manufacturing an article using a foamable adhesive sheet, the first intermediate layer and the second intermediate layer are arranged to reduce the stress applied to the bent portion when the foamable adhesive sheet is folded. The stress applied to the cut portion when the foamable adhesive sheet is cut can be relaxed. As a result, it is possible to suppress lifting and peeling of the first adhesive layer and the second adhesive layer from the base material when the foamable adhesive sheet is bent or cut.

For example, in the article 100 shown in FIG. 4, in the adhesive member 30, the first intermediate layer 13a is arranged between the base material 12 and the first cured adhesive layer 11a, and the first intermediate layer 13a is arranged between the base material 12 and the second cured adhesive layer 11b. A second intermediate layer 13b is arranged. In addition, although the adhesive member 30 has both the first intermediate layer 13a and the second intermediate layer 13b in FIG. 4, it may have only either one.

The adhesive member only needs to have at least one of the first intermediate layer and the second intermediate layer, for example, only the first intermediate layer disposed between the base material and the first cured adhesive layer. It may also have only a second intermediate layer disposed between the base material and the second cured adhesive layer, and a first intermediate layer disposed between the base material and the first cured adhesive layer; It may have both a base material and a second intermediate layer disposed between the second cured adhesive layer. Among these, it is preferable that the first intermediate layer is disposed between the base material and the first cured adhesive layer, and that the second intermediate layer is disposed between the base material and the second cured adhesive layer.

The materials included in the first intermediate layer and the second intermediate layer are materials that can enhance the adhesion between the base material and the first cured adhesive layer and the second cured adhesive layer, and can also alleviate stress. If so, it is not particularly limited, and is appropriately selected depending on the materials of the base material, the first cured adhesive layer, the second cured adhesive layer, and the like. Examples include polyester, polyvinyl chloride, polyvinyl acetate, polyurethane, polymers obtained by copolymerizing at least two thereof, crosslinked products thereof, and mixtures thereof.

The crosslinked product is a crosslinked product obtained by crosslinking the above resin with a curing agent. Examples of the curing agent include isocyanate curing agents. Further, for example, when the reactive group/NCO equivalent is 1, it is preferable to add the isocyanate curing agent to the resin at a ratio of 0.5% by mass or more and 20% by mass or less.

Among these, it is preferable that the first intermediate layer and the second intermediate layer contain a crosslinked resin. Note that crosslinked resin refers to one that does not melt even at high temperatures. This makes it possible to improve adhesive strength at high temperatures, that is, heat resistance.

The thickness of the first intermediate layer and the second intermediate layer is not particularly limited, but is, for example, 0.1 μm or more, may be 0.5 μm or more, or may be 1 μm or more. If the first intermediate layer or the second intermediate layer is too thin, when manufacturing an article using a foam adhesive sheet, the first adhesive layer or the second adhesive layer from the base material will be removed when the foam adhesive sheet is bent or cut. There is a possibility that the effect of suppressing layer peeling cannot be sufficiently obtained. On the other hand, the thickness of the first intermediate layer and the second intermediate layer is, for example, 4 μm or less, and may be 3.5 μm or less. The first intermediate layer and the second intermediate layer themselves usually do not have high heat resistance, so if the first intermediate layer or the second intermediate layer is too thick, the heat resistance (adhesion strength at high temperatures) may decrease. There is.

The first intermediate layer and the second intermediate layer can be formed, for example, by applying a resin composition and removing the solvent. Examples of coating methods include roll coating, reverse roll coating, transfer roll coating, gravure coating, gravure reverse coating, comma coating, rod coating, blade coating, bar coating, wire bar coating, die coating, lip coating, and dip coating. Can be mentioned.

2. First Member and Second Member The first member and second member in this embodiment are appropriately selected depending on the use of the article, etc. The first member and the second member are preferably members that require adhesion and insulation. For example, parts of electric/electronic equipment may be mentioned, and specific examples thereof include stator cores and coils of stators for rotating electric machines, cores and permanent magnets of embedded magnet type motors, and the like.

3. Article Manufacturing Method The article manufacturing method of this embodiment will be described in the section "B. Article Manufacturing Method" below.

II. Second Embodiment of Article A second embodiment of the article according to the present disclosure is an article having a first member, a second member, and an adhesive member disposed between the first member and the second member. The adhesive member has at least a cured adhesive layer, and the cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, In a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is 4 mm in the direction perpendicular to the thickness direction of the foam layer. Less than 7 pieces per length.

FIGS. 1 to 3 are schematic cross-sectional views showing an example of the article of this embodiment. Note that since FIGS. 1 to 3 were described in the section of the first embodiment above, their explanations will be omitted here.

In the article, when the first member and the second member are, for example, parts of electric/electronic equipment, specifically, the stator core and coil of a stator for a rotating electric machine, or the core and permanent magnet of an embedded magnet type motor. etc., the distance of the gap between the first member and the second member is, for example, about several hundred μm. In this case, the thickness of the adhesive member is, for example, about several hundred μm, and the thickness of the cured adhesive layer of the adhesive member is also, for example, about several hundred μm.

In the above-mentioned article, when the adhesive member has one cured adhesive layer and the cured adhesive layer is a foam layer, if there are large bubbles with a size of 100 μm or more, In the area where such air bubbles exist, the cured adhesive layer is not in contact with the first member and the second member, or the contact area between the cured adhesive layer and the first member and the area between the cured adhesive layer and the second member are small. The contact area becomes very small. Therefore, it is thought that adhesion failures such as peeling, lifting, and cracking of the cured adhesive layer tend to occur starting from the bubbles.

In contrast, in the article of this embodiment, when the adhesive member has one cured adhesive layer and the cured adhesive layer is a foam layer, a cross section parallel to the thickness direction of the foam layer In this method, the number of bubbles having a length of 100 μm or less in the thickness direction of the foam layer is less than or equal to a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer, thereby preventing poor adhesion. Can be suppressed. Therefore, it is possible to improve adhesiveness.

Further, in the above-mentioned article, the adhesive member has a first cured adhesive layer and a second cured adhesive layer, and the first cured adhesive layer and the second cured adhesive layer are foam layers. In this case, if there are large bubbles with a size of 100 μm or more, the first cured adhesive layer may not be in contact with the first member or the second cured adhesive layer may not be in contact with the first member in the area where such bubbles are present. or the contact area between the first cured adhesive layer and the first member is very small, or the contact area between the second cured adhesive layer and the second member is very small. or Therefore, it is thought that adhesion defects such as peeling, lifting, and cracking of the first cured adhesive layer and the second cured adhesive layer tend to occur starting from the bubbles.

In contrast, in the article of this embodiment, the adhesive member has a first cured adhesive layer and a second cured adhesive layer, and the first cured adhesive layer and the second cured adhesive layer are foam layers. In some cases, in a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is within a predetermined range with respect to the thickness of the foam layer is Adhesion failure can be suppressed by being less than or equal to a predetermined value per predetermined length in the direction perpendicular to the thickness direction. Therefore, it is possible to improve adhesiveness.

Note that the same applies when the adhesive member has a first cured adhesive layer and a second cured adhesive layer, and either one of the first cured adhesive layer and the second cured adhesive layer is a foam layer. In addition, it is possible to suppress adhesion defects and improve adhesion.

In addition, in the above-mentioned article, the adhesive member has a first cured adhesive layer, a base material, and a second cured adhesive layer in this order, and the first cured adhesive layer and the second cured adhesive layer are In the case of a foam layer, if there are large air bubbles whose size is approximately the same as the thickness of the foam layer, the first cured adhesive layer will bond to the first member and the base in areas where such air bubbles are present. the second cured adhesive layer is not in contact with the second member and the base material, or the contact area between the first cured adhesive layer and the first member and the base material is extremely small. , the contact area between the second cured adhesive layer and the second member and base material becomes very small. Therefore, it is thought that adhesion defects such as peeling, lifting, and cracking of the first cured adhesive layer and the second cured adhesive layer tend to occur starting from the bubbles.

In contrast, in the article of this embodiment, the adhesive member has a first cured adhesive layer, a base material, and a second cured adhesive layer in this order, and the first cured adhesive layer and the second cured adhesive layer is a foam layer, the number of cells whose length in the thickness direction of the foam layer is within a predetermined range with respect to the thickness of the foam layer in a cross section parallel to the thickness direction of the foam layer is less than or equal to a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer, thereby making it possible to suppress poor adhesion. Therefore, it is possible to improve adhesiveness.

In the article of this embodiment, the adhesive member, the first member, and the second member can be the same as those of the first embodiment.

Furthermore, the method for manufacturing the article of this embodiment will be described in the section "B. Method for manufacturing article" below.

The cured adhesive layer in this embodiment is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent, and has air bubbles inside. In a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. Less than 7 pieces. Among these, the number of bubbles is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0.

Among others, in a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is 150 μm or more is 4 mm in the direction perpendicular to the thickness direction of the foam layer. The number of pieces per length is preferably less than 7, more preferably 3 or less, even more preferably 2 or less, particularly preferably 1 or less, and preferably 0. Most preferred.

Further, in a cross section parallel to the thickness direction of the foam layer, the length of the foam layer in the thickness direction is 100 μm or more, and the foam layer and other cells adjacent to the foam layer are The number of bubbles having a distance of 3 μm or less from the interface of the member is preferably less than 7, and preferably 3 or less, per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. The number is more preferably 2 or less, even more preferably 1 or less, and most preferably 0. In areas where air bubbles exist as described above, the cured adhesive layer is not in contact with other members adjacent to the cured adhesive layer, or the contact area between the cured adhesive layer and other members adjacent to the cured adhesive layer is very large. becomes smaller. Therefore, it is thought that adhesion failures such as peeling, lifting, and cracking of the cured adhesive layer tend to occur starting from the bubbles.

Note that the distance between the bubbles and the interfaces of the foam layer and other members adjacent to the foam layer is, for example, as shown in FIG. The distance u1 to the interface of another member (for example, the first member 20a) adjacent to one surface, and the distance u1 from the end of the bubble 31 to the foam layer 15a and other surfaces adjacent to the foam layer 15a. It refers to the distance u2 to the interface of a member (for example, the base material 12).

B. Method for manufacturing an article The method for manufacturing an article in the present disclosure has two embodiments. Each embodiment will be described below.

I. First embodiment of the method for manufacturing an article The first embodiment of the method for manufacturing an article according to the present disclosure is a method for manufacturing an article using a foamable adhesive sheet having at least an adhesive layer, the adhesive layer being a curable adhesive. a foaming agent-containing adhesive layer containing a foaming agent and a foaming agent, a step of arranging the foamable adhesive sheet between a first member and a second member, and a foaming agent-containing adhesive layer of the foamable adhesive sheet. and an adhesion step of foaming and curing to form a foam layer, and adhering the first member and the second member, and the foaming curing conditions in the adhesion step are set in a direction parallel to the thickness direction of the foam layer. In the cross section, the number of cells whose length in the thickness direction of the foam layer is equal to or greater than the value of the thickness of the foam layer - 6 μm is 4 mm long in the direction perpendicular to the thickness direction of the foam layer. Set so that the number of hits is less than 7.

FIGS. 5(a) to 5(b) are process diagrams illustrating the method for manufacturing the article of this embodiment. First, as shown in FIG. 5(a), the foamable adhesive sheet 10 is placed between the first member 20a and the second member 20b. The foamable adhesive sheet 10 has an adhesive layer 1, and the adhesive layer 11 is a foaming agent-containing adhesive layer 5 containing a curable adhesive and a foaming agent. Next, as shown in FIG. 5(b), the foaming agent-containing adhesive layer 5 (adhesive layer 1) of the foamable adhesive sheet 10 is foamed and cured to form a cured adhesive layer 11 which is a foam layer 15, and the cured adhesive layer 11 is formed as a foam layer 15. An adhesive member 30 having a layer 11 bonds the first member 20a and the second member 20b. At this time, the foam curing conditions are set such that, in a cross section parallel to the thickness direction D1 of the foam layer 15, the length s of the foam layer 15 in the thickness direction D1 is The number of bubbles within a predetermined range with respect to the thickness t of the foam layer 15 is set to be below a predetermined value per a predetermined length L in the direction D2 perpendicular to the thickness direction D1 of the foam layer 15. do. Thereby, article 100 is obtained.

FIGS. 6(a) to 6(c) are process diagrams illustrating the method for manufacturing the article of this embodiment. First, as shown in FIG. 6(a), the foamable adhesive sheet 10 is attached to the second member 20b. The foamable adhesive sheet 10 has a first adhesive layer 1a and a second adhesive layer 1b, and the first adhesive layer 1a and the second adhesive layer 1b each contain a curable adhesive and a foaming agent. These are foaming agent-containing

adhesive layers

5a and 5b. At this time, the surface of the second adhesive layer 11b of the foamable adhesive sheet 10 is attached to the second member 20b. Next, as shown in FIG. 6(b), the second member 20b on which the foamable adhesive sheet 10 is arranged is inserted into the hole of the first member 20a. Next, as shown in FIG. 6(c), each of the foaming agent-containing

adhesive layers

5a and 5b (first adhesive layer 1a, second adhesive layer 1b) of the foamable adhesive sheet 10 is foamed and cured to form a foam layer 15a. , 15b, and the first member 20a and the second member 20b are bonded together by the adhesive member 30 having the first cured adhesive layer 11a and the second cured adhesive layer 11b. do. At this time, the foam curing conditions are set, for example, as shown in FIG. The length s of D1 is within a predetermined range with respect to the thicknesses t1 and t2 of the foam layers 15a and 15b.The number of bubbles is a predetermined length in the direction D2 perpendicular to the thickness direction D1 of the foam layers 15a and 15b. The value is set to be below a predetermined value per length L. Thereby, article 100 is obtained.

In addition, in FIGS. 6(a) to (c), both the first adhesive layer 1a and the second adhesive layer 1b are foaming agent-containing

adhesive layers

5a and 5b containing a curable adhesive and a foaming agent. However, either one of the first adhesive layer and the second adhesive layer may be a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent.

Furthermore, in FIGS. 6(a) to (c), the foamable adhesive sheet 10 is attached to both sides of the second member 20b, but the foamable adhesive sheet may be attached to one side of the second member.

In the method for manufacturing the article of this embodiment, as described in the section of the first embodiment of the article above, the foam curing conditions in the adhesion step are set so that the foam hardens in the cross section parallel to the thickness direction of the foam layer. The number of cells whose length in the thickness direction is within a predetermined range with respect to the thickness of the foam layer is below a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer. By setting this, it is possible to suppress poor adhesion and improve adhesion. Therefore, an article with high reliability and durability can be obtained.

In this specification, for convenience, in the foamable adhesive sheet, the adhesive layer located on the first member side is referred to as the first adhesive layer, and the adhesive layer located on the second member side is referred to as the second adhesive layer.

Hereinafter, the foamable adhesive sheet used in the method of manufacturing the article of this embodiment and each step of the method of manufacturing the article of this embodiment will be described.

1. Foamable Adhesive Sheet The foamable adhesive sheet in this embodiment has at least an adhesive layer, and the adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent.

The foamable adhesive sheet only needs to have at least an adhesive layer. For example, as shown in FIG. 7, the foamable adhesive sheet 10 may have one adhesive layer 1. In this case, the adhesive layer 1 is a foaming agent-containing adhesive layer 5 containing a curable adhesive and a foaming agent. Further, as shown in FIG. 8, for example, the foamable adhesive sheet 10 may have a first adhesive layer 1a and a second adhesive layer 1b. In this case, for example, as shown in FIG. 8, both the first adhesive layer 1a and the second adhesive layer 1b may be foaming agent-containing

adhesive layers

5a and 5b containing a curable adhesive and a foaming agent. Although not shown, either one of the first adhesive layer and the second adhesive layer may be a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent. Further, as shown in FIG. 9, for example, the foamable adhesive sheet 10 may include a first adhesive layer 1a, a base material 12, and a second adhesive layer 1b in this order. In this case, for example, as shown in FIG. 9, both the first adhesive layer 1a and the second adhesive layer 1b may be foaming agent-containing

adhesive layers

5a and 5b containing a curable adhesive and a foaming agent. Although not shown, either one of the first adhesive layer and the second adhesive layer may be a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent.

Hereinafter, each structure of the foamable adhesive sheet will be explained.

(1) Adhesive layer In this embodiment, the adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent.

(a) Characteristics of Adhesive Layer When the foamable adhesive sheet in this embodiment has one adhesive layer, the adhesive layer is preferably substantially non-adhesive (tack-free). Since the adhesive layer is substantially non-adhesive (tack-free), a foamable adhesive sheet with good slip properties and anti-blocking properties can be obtained. Therefore, the handleability and workability of the foamable adhesive sheet can be improved. Specifically, in the placement process, the foam adhesive sheet may be smoothly inserted into the gap between the first member and the second member, or if the first member has holes or grooves, the holes in the first member may be inserted smoothly. The second member can be smoothly inserted into the gap after the foam adhesive sheet is placed in the groove.

Here, "non-adhesive" is generally used to mean low adhesive strength, and in this specification, "non-adhesive" means that the foam adhesive sheet is wound into a roll and then , refers to a state in which it can be easily unrolled without resistance.

When the adhesive layer is substantially non-adhesive, specifically, the tack of the adhesive layer is preferably 0 gf or more and less than 10 gf, may be 5 gf or less, and may be 2 gf or less. . When the tack of the adhesive layer is within the above range, the adhesive layer can be made substantially non-adhesive, and a foamable adhesive sheet with good slip properties and anti-blocking properties can be obtained.

In addition, when the foamable adhesive sheet of this embodiment has a first adhesive layer and a second adhesive layer, or when it has a first adhesive layer, a base material, and a second adhesive layer in this order, the first adhesive Both the layer and the second adhesive layer may be substantially tack-free, or one of the first adhesive layer and the second adhesive layer may be substantially tack-free. (free), and the other may have adhesiveness (tackiness).

When both the first adhesive layer and the second adhesive layer are substantially non-tacky (tack-free), the foam adhesive sheet has one adhesive layer, and the adhesive layer is non-tacky. It is possible to obtain the same effect as when it is tack-free.

On the other hand, when one of the first adhesive layer and the second adhesive layer is substantially non-adhesive (tack-free) and the other is adhesive (tacky), for example, the first adhesive layer is substantially non-adhesive (tack-free) and the second adhesive layer has adhesiveness (tackiness), the second adhesive layer can have good adhesion to the second member. . Specifically, in the placement step, the surface of the second adhesive layer of the foamable adhesive sheet is pasted on the second member, and the second member with the foamable adhesive sheet pasted into the holes, grooves, etc. of the first member. When inserting the foam adhesive sheet, since the second adhesive layer has adhesiveness, the surface of the second adhesive layer of the foamable adhesive sheet can be attached to the second member using the adhesiveness of the second adhesive layer, Adhesion of the second adhesive layer to the second member can be improved. Thereby, when the second member to which the foamable adhesive sheet is attached is inserted into the hole or groove of the first member, peeling or displacement of the foamable adhesive sheet can be suppressed.

Furthermore, in the above case, since the second adhesive layer has adhesive properties, the second adhesive layer can have good reworkability. Therefore, for example, when attaching the surface of the second adhesive layer of the foam adhesive sheet to the second member using the adhesiveness of the second adhesive layer as described above, the misalignment of the foam adhesive sheet is corrected. be able to.

Furthermore, in the above case, since the first adhesive layer is non-adhesive, the first adhesive layer can have good slip properties. Therefore, for example, when inserting the second member to which the foamable adhesive sheet is pasted into the hole or groove of the first member as described above, the second member to which the foamable adhesive sheet is pasted can be smoothly inserted. It is possible to improve the insertability. Thereby, peeling and displacement of the foamable adhesive sheet can be suppressed. In addition, when aligning the first and second members by moving the second member relative to the first member, it is necessary to insert the second member into the hole or groove of the first member while the first member is being moved. The second member can be moved smoothly relative to the second member, and positioning can be easily performed.

In addition, in the above case, as mentioned above, the second adhesive layer has excellent adhesion with the second member, and the first adhesive layer has excellent slipperiness. Misalignment can be suppressed. Therefore, it suppresses the decrease in adhesion of the foamable adhesive sheet after foaming and curing due to peeling or misalignment of the foamable adhesive sheet, and also suppresses the adhesion of the foamable adhesive sheet after foaming and curing due to peeling or misalignment of the foamable adhesive sheet. Variations in strength can be reduced.

Furthermore, in the above case, since the second adhesive layer has adhesive properties, lifting of the second adhesive layer can be suppressed, for example, when the second adhesive layer is formed by a transfer method. Furthermore, as described later, when the second separator is disposed on the side of the second adhesive layer opposite to the first adhesive layer, the second adhesive layer has adhesiveness, so that the second separator can be easily peeled off, improving workability.

In addition, when the adhesive layer has adhesive properties, for example, it contains a relatively large amount of low molecular weight resin components, and thus fluidity tends to increase when the resin component softens during the foaming and curing process of the adhesive layer. Therefore, when the adhesive layer (adhesive layer containing a foaming agent) is foamed and cured to form a foam layer, the cells tend to connect with each other and become larger. Therefore, when one of the first adhesive layer and the second adhesive layer is substantially non-adhesive (tack-free) and the other is adhesive (tacky), the method for manufacturing the article of this embodiment is useful.

Specifically, when both the first adhesive layer and the second adhesive layer are substantially non-tacky, the tack of the first adhesive layer and the second adhesive layer may be greater than or equal to 0 gf and less than 10 gf, respectively. Preferably, it may be 5 gf or less, or 2 gf or less. By having the tack of the first adhesive layer and the second adhesive layer within the above range, the first adhesive layer and the second adhesive layer can be made substantially non-adhesive, and have good slip properties and anti-blocking properties. It can be made into a foamable adhesive sheet.

In addition, when the first adhesive layer is substantially non-adhesive (tack-free) and the second adhesive layer is adhesive (tacky), specifically, the tack of the first adhesive layer is 0 gf or more. , less than 10 gf, and the tack of the second adhesive layer is preferably 10 gf or more and 400 gf or less.

In the above case, the tack of the first adhesive layer is preferably 0 gf or more and less than 10 gf, and may be 5 gf or less, or 2 gf or less. By having the tack of the first adhesive layer within the above range, the first adhesive layer can be made substantially non-adhesive, and a foamable adhesive sheet with good sliding properties and anti-blocking properties can be obtained. .

Furthermore, in the above case, the tack of the second adhesive layer is preferably 10 gf or more, may be 30 gf or more, or may be 50 gf or more. If the tack of the second adhesive layer is too low, for example, when attaching the surface of the second adhesive layer of the foam adhesive sheet to the second member using the tack of the second adhesive layer, the second adhesive layer and There is a possibility that the adhesion between the two parts will decrease, or the adhesion between the second adhesive layer and the second member may be poor when inserting the second member with a foam adhesive sheet pasted into the hole or groove of the first member. This may cause the foam adhesive sheet to peel off or shift its position, resulting in decreased adhesion of the first adhesive layer and second adhesive layer after the foam is cured, or variations in adhesive strength. there's a possibility that. Further, the tack of the second adhesive layer is preferably 400 gf or less, may be 300 gf or less, or may be 200 gf or less. If the tack of the second adhesive layer is too high, reworkability will be reduced, and for example, when attaching the surface of the second adhesive layer of the foam adhesive sheet to the second member using the tack of the second adhesive layer, It may become difficult to correct misalignment of the foam adhesive sheet.

Here, the tack of the adhesive layer can be measured by a probe tack test based on JIS Z3284-3:2014. Specifically, a cylindrical stainless steel probe with a diameter of 5 mm was pressed against the surface of the adhesive layer of the foamable adhesive sheet at a temperature of 25°C, a load of 10.0 gf, and a speed of 30 mm/min. After holding it for a second, it is peeled off at a speed of 30 mm/min, and the load when peeled off is measured. This measurement is performed five times, and the average value is taken as the tack. As the probe tack tester, for example, a tacking tester "TAC-II" manufactured by RHESCA can be used.

Examples of means for controlling the tack of the adhesive layer include a method of adjusting the composition of the adhesive layer. Specifically, in an adhesive layer containing an epoxy resin and a curing agent, the tackiness of the adhesive layer can be reduced by using an epoxy resin that is solid at room temperature or using a curing agent that is solid at room temperature. can. On the other hand, in an adhesive layer containing an epoxy resin and a hardening agent, if an epoxy resin that is liquid at room temperature or a hardening agent that is liquid at room temperature is used, the adhesive layer tends to have higher stickiness. Furthermore, in the adhesive layer containing an epoxy resin and a curing agent, the tackiness of the adhesive layer can be reduced by containing an epoxy resin with a high softening temperature or an epoxy resin with a large weight average molecular weight. For example, the adhesive layer contains multiple types of epoxy resins with different softening temperatures, that is, the adhesive layer has a softening temperature of 25°C or higher and a softening temperature higher than that of the first epoxy resin. By containing other epoxy resins that have a temperature higher than 10° C., the tackiness of the adhesive layer can be reduced. Alternatively, for example, the adhesive layer may contain a plurality of types of epoxy resins having different weight average molecular weights, that is, the adhesive layer may contain one epoxy resin and a weight average molecular weight of 370 or more, and the adhesive layer may contain one epoxy resin and the other epoxy resin. By containing another epoxy resin having a weight average molecular weight of 300 or more higher than the weight average molecular weight, the adhesiveness of the adhesive layer can be reduced. More specifically, in the adhesive layer containing an epoxy resin and a curing agent, as described above, the epoxy resins include a first epoxy resin with a low softening temperature and a low molecular weight, and a second epoxy resin with a high softening temperature and a high molecular weight. By containing two epoxy resins, the adhesiveness of the adhesive layer can be reduced. On the other hand, in an adhesive layer containing an epoxy resin and a curing agent, if an epoxy resin with a low softening temperature or an epoxy resin with a small weight average molecular weight is contained, the adhesive layer tends to have higher tackiness. Further, in the adhesive layer containing an epoxy resin and a curing agent, the adhesiveness of the adhesive layer can be reduced by containing an acrylic resin that is compatible with the epoxy resin, as described above. Furthermore, by adding a tackifying resin (tackifier) to the adhesive layer, the adhesiveness of the adhesive layer tends to increase. Note that if a curing agent that is liquid at room temperature is used, it tends to have higher tackiness, but storage stability may decrease. It is preferable to adjust the tack of the adhesive layer by adjusting.

Here, "adhesion" is a concept included in "adhesion." A distinction is sometimes made in that adhesion is used to mean a temporary adhesion phenomenon, whereas adhesion is used to mean a substantially permanent adhesion phenomenon (Iwanami Shoten Physical and Chemistry Dictionary 5th Edition). "Adhesiveness" and "adhesive force" refer to the property of adhering by pressure sensitivity and the adhesion force at that time.

In addition, in this specification, "adhesiveness of the adhesive layer" and "adhesive force of the adhesive layer" refer to the adhesiveness and adhesive force that the adhesive layer has before curing, unless there are special circumstances. Moreover, in this specification, "adhesiveness of the adhesive layer" and "adhesive force of the adhesive layer" refer to the adhesiveness and adhesive force that the adhesive layer has after curing, unless there are special circumstances.

(b) Material of adhesive layer The adhesive layer in this embodiment contains a curable adhesive and a foaming agent.

The material of the adhesive layer is the same as that described in the section "A. Article" above, so a description thereof will be omitted here.

The case where the curable adhesive is an epoxy resin adhesive, and the curable adhesive has a softening temperature of 50°C or higher and an epoxy equivalent of 5000 g/eq or lower, as described above. When the adhesive layer contains a first epoxy resin and a second epoxy resin whose softening temperature is higher than that of the first epoxy resin and whose weight average molecular weight is 20,000 or more, the content of the first epoxy resin is For example, when the resin component contained in 100 parts by mass is 1 part by mass or more, it may be 3 parts by mass or more, it may be 5 parts by mass or more, and it is 10 parts by mass or more. The amount may be 15 parts by mass or more, or may be 25 parts by mass or more. If the content of the first epoxy resin is too small, the adhesiveness and blocking resistance after foaming and curing may decrease. On the other hand, the content of the first epoxy resin is, for example, 90 parts by mass or less, may be 80 parts by mass or less, and 70 parts by mass or less, when the resin component contained in the adhesive layer is 100 parts by mass. The amount may be 60 parts by mass or less, 50 parts by mass or less, or 40 parts by mass or less. If the content of the first epoxy resin is too high, the content of the second epoxy resin and acrylic resin will be relatively low, resulting in non-stick properties, anti-blocking properties, adhesion to the substrate after foaming and curing. It may not be possible to balance the cracking resistance of the foam and the adhesion after foaming and curing.

Further, in the above case, the content of the second epoxy resin is, for example, 10 parts by mass or more, and may be 15 parts by mass or more, when the resin component contained in the adhesive layer is 100 parts by mass. It may be 20 parts by mass or more, 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, The amount may be 45 parts by mass or more. If the content of the second epoxy resin is too small, tackiness may increase and blocking resistance may decrease. On the other hand, the content of the second epoxy resin is, for example, 90 parts by mass or less, may be 85 parts by mass or less, and 80 parts by mass or less, when the resin component contained in the adhesive layer is 100 parts by mass. The amount may be 75 parts by mass or less. If the content of the second epoxy resin is too high, the content of the first epoxy resin and acrylic resin will be relatively small, resulting in non-stick properties, blocking resistance, adhesion to the substrate after foaming and curing, and It may not be possible to balance the cracking resistance of the foam and the adhesion after foaming and curing.

The ratio of the first epoxy resin to the total of the first epoxy resin and the second epoxy resin is, for example, 5% by mass or more, may be 10% by mass or more, may be 15% by mass or more, and may be 20% by mass or more. It may be more than % by mass. On the other hand, the above proportion of the first epoxy resin is, for example, 80% by mass or less, may be 75% by mass or less, or may be 60% by mass or less.

Further, the total ratio of the first epoxy resin and the second epoxy resin to all the epoxy resins contained in the adhesive layer is, for example, 50% by mass or more, may be 70% by mass or more, and may be 90% by mass or more. It may be 100% by mass.

When the first adhesive layer is substantially non-tacky and the second adhesive layer is tacky, and the curable adhesive is an epoxy resin adhesive, the first adhesive layer is substantially non-adhesive as described above. As described above, a first epoxy resin having a softening temperature of 50° C. or higher and an epoxy equivalent of 5000 g/eq or lower, and a first epoxy resin having a softening temperature higher than the first epoxy resin and a weight average molecular weight of 20,000 It is preferable to contain the above-mentioned second epoxy resin. On the other hand, in the second adhesive layer, it is preferable to use an epoxy resin that is liquid at room temperature, such as a bisphenol A epoxy resin or a bisphenol F epoxy resin, and an epoxy resin that has a low softening point. This is because by using these epoxy resins, the tack of the second adhesive layer can be easily adjusted within a predetermined range.

When the curable adhesive is an epoxy resin adhesive and the adhesive layer further contains an acrylic resin that is compatible with the epoxy resin, the content of the acrylic resin is determined by the resin component contained in the adhesive layer. is 100 parts by mass, for example, it is 1 part by mass or more, may be 3 parts by mass or more, may be 5 parts by mass or more, may be 7 parts by mass or more, and 10 parts by mass. or more. If the content of the acrylic resin is too small, the adhesion to the substrate after foaming and curing, the cracking resistance after foaming and curing, and the adhesiveness after foaming and curing may decrease. On the other hand, the content of the acrylic resin is, for example, 60 parts by mass or less, may be 50 parts by mass or less, and may be 40 parts by mass or less, when the resin component contained in the adhesive layer is 100 parts by mass. The amount may be 35 parts by mass or less, or 30 parts by mass or less. If the content of acrylic resin is too high, the content of the first epoxy resin and the second epoxy resin will be relatively small, resulting in poor non-stick properties, anti-blocking properties, adhesion to the substrate after foaming and curing, and poor foaming and curing. It may not be possible to balance the cracking resistance of the foam and the adhesion after foaming and curing. Furthermore, if the content of the acrylic resin is too large, the film strength may decrease.

Further, the content of the curing agent is, for example, 1 part by mass or more and 40 parts by mass or less, when the resin component contained in the adhesive layer is 100 parts by mass. For example, when using an imidazole-based curing agent as a main component, the content of the curing agent is, for example, 1 part by mass or more and 15 parts by mass or less, when the resin component contained in the adhesive layer is 100 parts by mass. It is preferable that On the other hand, when using a phenolic curing agent as the main component, the content of the curing agent is, for example, 5 parts by mass or more and 40 parts by mass or less, when the resin component contained in the adhesive layer is 100 parts by mass. It is preferable that Note that using an imidazole curing agent or a phenolic curing agent as a main component as a curing agent means that the mass proportion of the imidazole curing agent or phenol curing agent is the largest in the curing agent.

The content of the foaming agent is, for example, 0.5 parts by mass or more, may be 2 parts by mass or more, and may be 3 parts by mass or more when the resin component contained in the adhesive layer is 100 parts by mass. The amount may be 4 parts by mass or more, or 5 parts by mass or more. On the other hand, the content of the foaming agent is, for example, 25 parts by mass or less, may be 20 parts by mass or less, or may be 15 parts by mass or less, based on 100 parts by mass of the resin component contained in the adhesive layer. . If the content of the foaming agent is too large, the content of the curable adhesive will be relatively small, which may reduce the adhesiveness after foaming and curing.

At least one of the first adhesive layer and the second adhesive layer may contain a foaming agent. Among these, when the first adhesive layer is substantially non-adhesive and the second adhesive layer is adhesive, it is preferable that the first adhesive layer contains a foaming agent. This is because the inclusion of a foaming agent increases surface roughness, reduces the coefficient of friction, and improves slipperiness. In particular, it is preferred that both the first adhesive layer and the second adhesive layer contain a foaming agent. By containing the foaming agent in both the first adhesive layer and the second adhesive layer, the adhesiveness of the first adhesive layer and the second adhesive layer after foaming and curing can be improved.

The total ratio of the epoxy resin and the acrylic resin to the resin component contained in the adhesive layer is, for example, 70% by mass or more, may be 80% by mass or more, may be 90% by mass or more, and may be 100% by mass. It may be %.

The content of the resin component contained in the adhesive layer is, for example, 60% by mass or more, may be 70% by mass or more, may be 80% by mass or more, or may be 90% by mass or more.

(c) Structure of adhesive layer The adhesive layer can be foamed at a foaming ratio of, for example, 1.5 times or more and 15 times or less. The expansion ratio may be, for example, 3.5 times or more, 4 times or more, or 4.5 times or more. Further, the expansion ratio may be, for example, 9 times or less, 8.5 times or less, or 8 times or less. If the foaming ratio is too small or too large, the adhesiveness after foaming and curing may decrease.

Here, the foaming ratio can be determined by the following formula.
Foaming ratio (times) = Thickness of adhesive layer after foaming and curing / Thickness of adhesive layer before foaming and curing

The thickness of the adhesive layer is not particularly limited, but is preferably equal to or larger than the average particle size of the foaming agent, for example, 10 μm or more, may be 15 μm or more, or may be 20 μm or more. If the adhesive layer is too thin, it may not be possible to obtain sufficient adhesion to the base material and adhesion after foaming and curing. On the other hand, the thickness of the adhesive layer is, for example, 200 μm or less, may be 150 μm or less, or may be 100 μm or less. If the adhesive layer is too thick, the surface quality may deteriorate.

The adhesive layer may be a continuous layer or a discontinuous layer. Examples of the discontinuous layer include patterns such as stripes and dots. Further, the surface of the adhesive layer may have an uneven shape such as embossing.

The adhesive layer can be formed, for example, by applying an adhesive composition containing the above-mentioned curable adhesive and foaming agent, and removing the solvent. Examples of coating methods include roll coating, reverse roll coating, transfer roll coating, gravure coating, gravure reverse coating, comma coating, rod coating, blade coating, bar coating, wire bar coating, die coating, lip coating, dip coating, etc. can be mentioned.

The adhesive composition may or may not contain a solvent. Note that the term "solvent" as used herein has a broad meaning that includes not only a strict solvent (a solvent that dissolves a solute) but also a dispersion medium. Further, the solvent contained in the adhesive composition is evaporated and removed when the adhesive composition is applied and dried to form an adhesive layer.

The adhesive composition can be obtained by mixing the above-mentioned components, kneading and dispersing as necessary. For mixing and dispersing methods, common kneading and dispersing machines such as two-roll mills, three-roll mills, pebble mills, trom mills, Szegvari attritors, high-speed impeller dispersing machines, high-speed stone mills, high-speed impact mills, and despars are used. , high-speed mixer, ribbon blender, co-kneader, intensive mixer, tumbler, blender, desperser, homogenizer, and ultrasonic dispersion machine are applicable.

(2) Base material The foamable adhesive sheet in this embodiment may have a base material between the first adhesive layer and the second adhesive layer. Since the base material is the same as described in the section "A. Article" above, the explanation here will be omitted.

(3) Other configurations (a) First intermediate layer and second intermediate layer The foamable adhesive sheet in this embodiment may have a first intermediate layer between the base material and the first adhesive layer. Moreover, the foamable adhesive sheet in this embodiment may have a second intermediate layer between the base material and the second adhesive layer. The first intermediate layer and the second intermediate layer are the same as those described in the section "A. Article" above, so the description thereof will be omitted here.

For example, in the foamable adhesive sheet 10 shown in FIG. Layer 13b is arranged. In addition, although the foamable adhesive sheet 10 has both the first intermediate layer 13a and the second intermediate layer 13b in FIG. 10, it may have only either one.

(b) Separator When the foamable adhesive sheet in this embodiment has one adhesive layer, it may have a separator on one or both sides of the adhesive layer. Further, the foamable adhesive sheet in this embodiment has a first adhesive layer and a second adhesive layer, or a first adhesive layer, a base material, and a second adhesive layer in this order. The layer may have a first separator on the side opposite to the second adhesive layer, and the second adhesive layer may have a second separator on the side opposite to the first adhesive layer. .

When the foamable adhesive sheet has a separator, the separator is peeled off from the foamable adhesive sheet when the foamable adhesive sheet is placed between the first member and the second member.

The separator is not particularly limited as long as it can be peeled off from the adhesive layer, and it can have enough strength to protect the adhesive layer. Examples of such a separator include a release film, release paper, and the like. Further, the separator may have a single layer structure or a multilayer structure.

Examples of the single-layer separator include fluororesin films.

Further, as a separator with a multilayer structure, for example, a laminate having a release layer on one or both sides of a base layer can be mentioned. Examples of the base material layer include resin films such as polypropylene, polyethylene, and polyethylene terephthalate, and papers such as high-quality paper, coated paper, and impregnated paper. The material for the release layer is not particularly limited as long as it has release properties, and examples include silicone compounds, organic compound-modified silicone compounds, fluorine compounds, aminoalkyd compounds, melamine compounds, acrylic compounds, polyester compounds, and long-lasting materials. Examples include chain alkyl compounds. These compounds may be of emulsion type, solvent type or non-solvent type.

The first separator and the second separator may be the same or different. In particular, when the first adhesive layer is substantially non-adhesive and the second adhesive layer is adhesive, the first separator has heavy releasability and the second separator has light releasability. is preferred. For example, when inserting the second member on which the foam adhesive sheet is placed into the hole of the first member after placing the foam adhesive sheet on the second member, the foam adhesive sheet is placed on the second member. By pasting the second adhesive layer side and making the first adhesive layer side of the foam adhesive sheet the front side, the adhesion between the second member and the foam adhesive sheet when inserted is improved, and the foam adhesive sheet is placed The insertability of the second member can be improved. In this case, between the first separator and the second separator, the second separator will be peeled off, so the first separator has heavy releasability and the second separator has light releasability, so that the second separator can be peeled off more easily than the first separator.

Note that light peeling and heavy peeling refer to the degree of force required to peel off the first separator and second separator from the first adhesive layer and the second adhesive layer, and light peeling has a higher peeling force than heavy peeling. means that is small.

(4) Foamable adhesive sheet The thickness of the foamable adhesive sheet in this embodiment is, for example, 10 μm or more, and may be 20 μm or more. On the other hand, the thickness of the foamable adhesive sheet is, for example, 1000 μm or less, and may be 200 μm or less.

The foamable adhesive sheet in this embodiment preferably has good shape retention. It is preferable that the shape retention property is good. The bending moment based on JIS P8125 corresponding to ISO 2493 is, for example, 0.1 gf·cm or more, and may be 1 gf·cm or more. On the other hand, the bending moment is, for example, less than 40 gf·cm, and may be less than 30 gf·cm. Conventionally, a common method for foam adhesive sheets is to increase the bending moment to improve shape retention and ease of insertion into narrow gaps. In contrast, the inventors of the present disclosure believe that shape retention can be ensured by devising the shape, and that a high bending moment has other problems, so in consideration of other characteristics, It has been found that the bending moment is preferably within the above range. If the bending moment is smaller than the above range, it may be difficult to maintain the shape even if measures such as folding are used. Furthermore, if the bending moment is larger than the above range, the shape will return to its original shape after the bending process, so it is necessary to heat it during the bending process or to add streaks to the crease. Heating can reduce the sheet life, and forming streaks can reduce the insulation properties of those areas. In addition, the foamable adhesive sheet in this embodiment has a high surface hardness so that the surface will not be damaged even when inserted at high speed.

The foamable adhesive sheet in this embodiment preferably has high adhesiveness after foaming and curing. The shear strength (adhesive strength) based on JIS K6850 corresponding to ISO 4587 at 23°C may be, for example, 1.50 MPa or more, 1.80 MPa or more, or 2.10 MPa or more. good. Further, the shear strength (adhesive strength) may be, for example, 0.50 MPa or more, 0.75 MPa or more, or 1.00 MPa or more at 130°C. For example, a high-strength acrylic foam adhesive tape that does not require heating has a shear strength (adhesive strength) of about 1 MPa or more and 2 MPa or less at room temperature, and has no heat resistance at 200°C. Therefore, if the shear strength (adhesive strength) is within the above range at 23° C., there is an advantage in terms of strength. Further, if the shear strength (adhesive strength) is within the above range at 130° C., it can be applied to automobile engine areas and other applications where heat resistance similar to that is required.

The foamable adhesive sheet in this embodiment preferably has high electrical insulation properties after foaming and curing. After foaming and curing of the foamable adhesive sheet, the dielectric breakdown voltage based on JIS C2107 corresponding to IEC 60454-2 is preferably, for example, 3 kV or more, and more preferably 5 kV or more. When the dielectric breakdown voltage is within the above range, it becomes possible to prevent rust and to be applied around copper wires. Further, after the foamable adhesive sheet is foamed and cured, the thermal conductivity is preferably, for example, 0.1 W/mK or more, and more preferably 0.15 W/mK or more. When the thermal conductivity is within the above range, the parts can be made smaller and the curing reaction during heating can be promoted.

The method for producing the foamable adhesive sheet in this embodiment is not particularly limited, and is appropriately selected depending on the layer structure of the foamable adhesive sheet.

2. Arrangement Step In the arrangement step in this embodiment, a foamable adhesive sheet is arranged between the first member and the second member.

The method of arranging the foamable adhesive sheet between the first member and the second member is appropriately selected depending on the types of the first member and the second member.

For example, there is a method of inserting a foam adhesive sheet between the first member and the second member, or a method of inserting a foam adhesive sheet into the hole or groove of the first member, and then inserting the foam adhesive sheet into the hole or groove of the first member. Examples include a method of inserting a second member into the gap after the foamable adhesive sheet is placed. Further, for example, when the first member has a hole or groove and the second member is placed in the hole or groove of the first member, and the first member and the second member are fixed by adhesive, After pasting the surface of the second adhesive layer of the foam adhesive sheet to the second member using the tack of the second adhesive layer of the foam adhesive sheet, the foam adhesive sheet is inserted into the holes and grooves of the first member. There is a method of arranging the pasted second member, and a method of placing a foam adhesive sheet in the hole or groove of the first member, and using the tack of the second adhesive layer of the foam adhesive sheet to fill the hole or groove of the first member. Examples include a method in which the surface of the second adhesive layer of the foamable adhesive sheet is pasted to the groove, and then the second member is placed in the hole or groove of the first member to which the foamable adhesive sheet is pasted.

3. Bonding Step In the bonding step in this embodiment, the foaming agent-containing adhesive layer of the foamable adhesive sheet is foamed and cured to form a foam layer, and the first member and the second member are bonded.

In addition, in the bonding process in this embodiment, the foam curing conditions are such that, in a cross section parallel to the thickness direction of the foam layer, the length in the thickness direction of the foam layer is the value of the thickness of the foam layer - 6 μm. The number of bubbles is set to be less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. Among these, the foam curing conditions are preferably set so that the number of bubbles is 3 or less, more preferably 2 or less, and 1 or less. is more preferable, and it is particularly preferable to set the number to zero.

Examples of methods for foaming and curing the foamable adhesive sheet include heating and light irradiation. Among these, it is preferable to foam and harden the foaming agent-containing adhesive layer of the foamable adhesive sheet by heating. The heating method is applicable even when the first member and the second member do not have transparency, such as metal members.

The heating conditions are set to meet the foaming and curing conditions described above. The heating conditions can be appropriately set depending on, for example, the type of curable adhesive or foaming agent contained in the adhesive layer.

The heating temperature is, for example, preferably within ±40°C of the maximum foaming temperature of the foaming agent, more preferably within ±30°C of the maximum foaming temperature of the foaming agent, and within ±20°C of the maximum foaming temperature of the foaming agent. It is even more preferable that there be. If the heating temperature is higher than the above range, even if the resin component is cured, the foaming agent will shrink, making it impossible to maintain the thickness of the adhesive layer during foaming, and the foam layer (cured adhesive layer) will shrink. ) The size of the bubbles tends to be relatively large compared to the thickness of the film. Therefore, adhesive strength may decrease. On the other hand, if the heating temperature is lower than the above range, the expansion of the foaming agent may become insufficient and the adhesive strength may decrease. In this case, interfacial destruction may easily occur between the cured adhesive layer and the first member or the second member.

Note that when the adhesive layer contains a plurality of foaming agents, the heating temperature for at least one foaming agent may be within the above range. Among the plurality of foaming agents, it is preferable that the heating temperature of the foaming agent with a higher content is within the above range. In particular, it is preferable that the heating temperature of all of the plurality of foaming agents be within the above range.

Further, the heating temperature is preferably, for example, at least -7°C or higher, the extrapolated maximum displacement temperature of the foamable adhesive sheet, or lower than the maximum displacement extrapolated temperature of the foamable adhesive sheet, which exceeds the maximum displacement temperature of the foamable adhesive sheet. It is more preferable that the extrapolated temperature is +15°C or more, and the extrapolated maximum displacement temperature of the foamable adhesive sheet is +63°C or less, and the extrapolated maximum displacement temperature of the foamable adhesive sheet is +23°C or more, and the extrapolated maximum displacement temperature of the foamable adhesive sheet. More preferably, the temperature is +43°C or lower. If the heating temperature is higher than the above range, even if the resin component is cured, the foaming agent will shrink, making it impossible to maintain the thickness of the adhesive layer during foaming, and the foam layer (cured adhesive layer) will shrink. ) The size of the bubbles tends to be relatively large compared to the thickness of the film. Therefore, adhesive strength may decrease. On the other hand, if the heating temperature is lower than the above range, the expansion of the foaming agent may become insufficient and the adhesive strength may decrease. In this case, interfacial destruction may easily occur between the cured adhesive layer and the first member or the second member.

Figure 11 shows the results of thermomechanical analysis (TMA) of a foamable adhesive sheet when a compressive load was applied, the temperature was raised at a predetermined temperature increase rate, and the displacement was measured. It is a graph illustrating a TMA curve with an axis. A TMA curve for a foamable adhesive sheet containing thermally expandable microcapsules as a foaming agent usually has a peak associated with expansion (foaming). In the TMA curve for a foamable adhesive sheet as shown in Figure 11, the tangent line at the temperature showing the maximum amount of displacement and the curve of the part of the TMA curve that shows expansion behavior as expansion (foaming) starts were differentiated. The temperature at the point of intersection with the tangent line at the minimum temperature is defined as the maximum displacement extrapolated temperature T _max1 of the foamable adhesive sheet. In the above case, it is preferable that the heating temperature is within a predetermined range with respect to the maximum displacement extrapolated temperature T _max1 .

Here, thermomechanical analysis of the foamable adhesive sheet is performed by the following method. First, a sample is prepared by punching out a foam adhesive sheet into a size of φ4 mm. Next, the sample was placed in an aluminum container with a diameter of 5 mm so that the surface of the second adhesive layer of the foamable adhesive sheet was on the bottom side. Next, an aluminum plate with a diameter of 4 mm is placed on top of the sample. Next, using a thermomechanical analyzer, the temperature is raised from 25° C. to 250° C. at a rate of 20° C./min, and measurement is performed in compression mode under a load of 10 mN. As the thermomechanical analyzer, a thermomechanical analyzer TMA7100 manufactured by Hitachi High-Tech Science Co., Ltd. can be used.

Note that the maximum amount of displacement is the maximum value of the amount of displacement in the TMA curve for the foamable adhesive sheet.

In addition, the maximum displacement extrapolated temperature is the tangent line at the temperature that shows the maximum displacement in the TMA curve for the foamable adhesive sheet, and the curve of the part of the TMA curve that shows expansion behavior with the start of expansion (foaming). Let it be the intersection with the tangent at the minimum temperature when differentiated.

Specifically, the heating temperature can be 130°C or higher and 200°C or lower.

The heating time can be, for example, 3 minutes or more and 3 hours or less.

II. Second embodiment of the method for manufacturing an article The second embodiment of the method for manufacturing an article according to the present disclosure is a method for manufacturing an article using a foamable adhesive sheet having at least an adhesive layer, the adhesive layer being a curable adhesive. a foaming agent-containing adhesive layer containing a foaming agent and a foaming agent, the step of arranging the foamable adhesive sheet between the first member and the second member; and the foaming agent-containing adhesive of the foamable adhesive sheet. an adhesion step of foaming and curing the layer to form a foam layer, and adhering the first member and the second member, the foaming curing conditions in the adhesion step being parallel to the thickness direction of the foam layer. In a cross section, the number of cells having a length of 100 μm or more in the thickness direction of the foam layer is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. Set.

FIGS. 5(a) to (b) and FIGS. 6(a) to (c) are process diagrams illustrating the method for manufacturing the article of this embodiment. Note that FIGS. 5(a) to 6(b) and FIGS. 6(a) to 6(c) were described in the section of the first embodiment above, so a description thereof will be omitted here.

In the method for manufacturing the article of this embodiment, as described in the second embodiment of the article above, the foam curing conditions in the adhesion step are set to Defective adhesion can be suppressed by setting the number of bubbles with a length of 100 μm or more in the thickness direction to be below a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer. , adhesion can be improved. Therefore, an article with high reliability and durability can be obtained.

The foamable adhesive sheet used in the method of manufacturing an article of this embodiment and the arrangement step of the method of manufacturing an article of this embodiment can be the same as in the first embodiment.

In addition, in the bonding process in this embodiment, the foam curing conditions are such that the number of cells whose length in the thickness direction of the foam layer is 100 μm or more in the cross section parallel to the thickness direction of the foam layer is The number is set to less than 7 per 4 mm in the direction perpendicular to the thickness direction of the body layer. Among these, the foam curing conditions are preferably set so that the number of bubbles is 3 or less, more preferably 2 or less, and 1 or less. is more preferable, and it is particularly preferable to set the number to zero.

The method of foaming and curing the foamable adhesive sheet and the heating conditions can be the same as in the first embodiment.

C. Foamable Adhesive Sheet The foamable adhesive sheet in the present disclosure has two embodiments. Each embodiment will be described below.

I. First Embodiment of the Foamable Adhesive Sheet The first embodiment of the foamable adhesive sheet in the present disclosure is a foamable adhesive sheet having at least an adhesive layer, the adhesive layer containing a curable adhesive and a foaming agent. a foaming agent-containing adhesive layer, the curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule, and the foamable adhesive sheet is When the foaming agent-containing adhesive layer is foamed and cured to form a foam layer by heating at a foaming temperature of ±20°C for 15 minutes, in a cross section parallel to the thickness direction of the foam layer, The number of cells whose length in the thickness direction is greater than or equal to the thickness of the foam layer - 6 μm is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.

FIG. 7 is a schematic cross-sectional view showing an example of the foamable adhesive sheet of this embodiment. The foamable adhesive sheet 10 in FIG. 7 has an adhesive layer 1. The foamable adhesive sheet 10 shown in FIG. The adhesive layer 1 is a foaming agent-containing adhesive layer 5 containing a curable adhesive and a foaming agent. The curable adhesive contained in the foaming agent-containing adhesive layer 5 (adhesive layer 1) is a thermosetting adhesive, and the foaming agent contained in the foaming agent-containing adhesive layer 5 (adhesive layer 1) is a thermosetting adhesive. It is a sex microcapsule. Furthermore, when the foaming adhesive sheet 10 is heated at a predetermined temperature for a predetermined time to foam and harden the foaming agent-containing adhesive layer 5 (adhesive layer 1) to form a foam layer 15, as shown in FIG. 12, for example, In a cross section parallel to the thickness direction D1 of the foam layer 15, the number of cells 31 whose length s in the thickness direction D1 of the foam layer 15 is within a predetermined range with respect to the thickness t of the foam layer 15 is , a predetermined value or less per predetermined length L in the direction D2 perpendicular to the thickness direction D1 of the foam layer 15.

FIG. 8 is a schematic cross-sectional view showing another example of the foamable adhesive sheet of this embodiment. The foamable adhesive sheet 10 in FIG. 9 has a first adhesive layer 1a and a second adhesive layer 1b. The first adhesive layer 1a and the second adhesive layer 1b are foaming agent-containing

adhesive layers

5a and 5b containing a curable adhesive and a foaming agent. The curable adhesive contained in the foaming agent-containing

adhesive layers

5a, 5b (first adhesive layer 1a, second adhesive layer 1b) is a thermosetting adhesive; The foaming agent contained in the first adhesive layer 1a and the second adhesive layer 1b) is a thermally expandable microcapsule. By heating the foamable adhesive sheet 10 at a predetermined temperature for a predetermined time, the foaming agent-containing

adhesive layers

5a and 5b (first adhesive layer 1a and second adhesive layer 1b) are respectively foamed and cured to form

foam layers

15a and 15b. For example, as shown in FIG. 13, in a cross section parallel to the thickness direction D1 of the foam layer 15a, the length s of the bubbles 31 in the thickness direction D1 of the foam layer 15a is The number of bubbles within a predetermined range with respect to the thickness t1 is equal to or less than a predetermined value or a predetermined length L in the direction D2 perpendicular to the thickness direction D1 of the foam layer 15a. Further, in a cross section parallel to the thickness direction D1 of the foam layer 15b, the length s of the foam layer 15b in the thickness direction D1 of the bubbles 31 is within a predetermined range with respect to the thickness t2 of the foam layer 15b. The number of bubbles is equal to or less than a predetermined value per predetermined length L in the direction D2 perpendicular to the thickness direction D1 of the foam layer 15b.

FIG. 9 is a schematic cross-sectional view showing another example of the foamable adhesive sheet of this embodiment. The foamable adhesive sheet 10 in FIG. 9 has a first adhesive layer 1a, a base material 12, and a second adhesive layer 1b in this order. Note that FIG. 9 is the same as FIG. 8 described above except that the base material 12 is disposed between the first adhesive layer 1a and the second adhesive layer 1b.

In addition, in FIGS. 8 and 9, both the first adhesive layer 1a and the second adhesive layer 1b are foaming agent-containing

adhesive layers

5a and 5b containing a curable adhesive and a foaming agent, but the first Either one of the adhesive layer and the second adhesive layer may be a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent.

In the foamable adhesive sheet of this embodiment, as described in the section of the first embodiment of the above-mentioned article, when the adhesive layer is a foaming agent-containing adhesive layer, the foamable adhesive sheet is heated at a predetermined temperature for a predetermined period of time. When the foaming agent-containing adhesive layer is foamed and cured by heating to form a foam layer, in a cross section parallel to the thickness direction of the foam layer, the length of the foam layer in the thickness direction is the same as that of the foam layer. When the number of bubbles within a predetermined range with respect to the thickness is equal to or less than a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer, poor adhesion can be suppressed. Therefore, it is possible to improve adhesiveness.

Each structure of the foamable adhesive sheet of this embodiment is the same as that described in the above sections "A. Article" and "B. Article manufacturing method", so the explanation here will be omitted.

In this embodiment, when the foaming adhesive layer is foamed and cured by heating the foamable adhesive sheet at the maximum foaming temperature of the foaming agent ±20°C for 15 minutes to form a foam layer, the thickness of the foam layer is In a cross section parallel to the width direction, the number of cells whose length in the thickness direction of the foam layer is equal to or greater than the value of the thickness of the foam layer - 6 μm is 4 mm in the direction perpendicular to the thickness direction of the foam layer. Less than 7 pieces per length. The number of bubbles is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0.

Note that when heating the foamable adhesive sheet, a support having a smooth surface is used, and the foamable adhesive sheet is placed on the smooth surface of the support before heating. The support is not particularly limited as long as it has a smooth surface and heat resistance, and for example, a glass substrate, a resin substrate, etc. can be used.

Furthermore, for the foamable adhesive sheet, the thickness direction of the foam layer is perpendicular to the plane direction of the support. Further, the direction perpendicular to the thickness direction of the foam layer is the plane direction of the support.

The use of the foamable adhesive sheet of this embodiment is not particularly limited. The foamable adhesive sheet of this embodiment can be used, for example, to manufacture the above-mentioned articles.

II. Second embodiment of the foamable adhesive sheet The second embodiment of the foamable adhesive sheet in the present disclosure is a foamable adhesive sheet having at least an adhesive layer, the adhesive layer containing a curable adhesive and a foaming agent. a foaming agent-containing adhesive layer, the curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule, and the foamable adhesive sheet is When the foaming agent-containing adhesive layer is foamed and cured to form a foam layer by heating at a foaming temperature of ±20°C for 15 minutes, in a cross section parallel to the thickness direction of the foam layer, The number of bubbles having a length of 100 μm or more in the thickness direction is less than 7 per 4 mm in the direction perpendicular to the thickness direction of the foam layer.

FIGS. 7 to 9 are schematic cross-sectional views showing an example of the foamable adhesive sheet of this embodiment. Note that since FIGS. 7 to 9 were described in the section of the first embodiment above, their explanations will be omitted here.

In the foamable adhesive sheet of this embodiment, as described in the section of the second embodiment of the above-mentioned article, when the adhesive layer is a foaming agent-containing adhesive layer, the foamable adhesive sheet is heated at a predetermined temperature for a predetermined period of time. When the foaming agent-containing adhesive layer is foamed and cured by heating to form a foam layer, the length in the thickness direction of the foam layer is 100 μm or more in a cross section parallel to the thickness direction of the foam layer. When the number of bubbles is equal to or less than a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer, poor adhesion can be suppressed. Therefore, it is possible to improve adhesiveness.

In this embodiment, when the foaming adhesive layer is foamed and cured by heating the foamable adhesive sheet at the maximum foaming temperature of the foaming agent ±20°C for 15 minutes to form a foam layer, the thickness of the foam layer is In a cross section parallel to the width direction, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. . The number of bubbles is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0.

Note that when heating the foamable adhesive sheet, heating may be performed after placing the foamable adhesive sheet on one side of the support. The support may be the same as in the first embodiment.

D. Adhesive Composition The adhesive composition in the present disclosure has two embodiments. Each embodiment will be described below.

I. First Embodiment of Adhesive Composition A first embodiment of the adhesive composition in the present disclosure is an adhesive composition containing a curable adhesive and a foaming agent, the curable adhesive comprising: The adhesive composition is a thermosetting adhesive, and the foaming agent is a thermally expandable microcapsule. When the coating film is foamed and cured by heating the film at the maximum foaming temperature of the foaming agent ±20°C for 15 minutes to form a foam layer, in a cross section parallel to the thickness direction of the foam layer, The number of cells whose length in the thickness direction of the foam layer is equal to or greater than the value of the thickness of the foam layer - 6 μm is 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. Less than one.

In the adhesive composition of this embodiment, as described in the section of the first embodiment of the above-mentioned article, the adhesive composition is applied to one surface of the support at a predetermined thickness, and the adhesive composition is When a foam layer is formed by foaming and curing the coating film by heating the coating film at a predetermined temperature for a predetermined time, the thickness of the foam layer is measured in a cross section parallel to the thickness direction of the foam layer. The number of bubbles whose length is within a predetermined range relative to the thickness of the foam layer is less than or equal to a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer, thereby preventing adhesion failure. Can be suppressed. Therefore, it is possible to improve adhesiveness.

Each component of the adhesive composition of this embodiment is the same as described in the above sections "A. Article" and "B. Method for manufacturing article", so a description thereof will be omitted here.

In this embodiment, the adhesive composition is applied to one side of the support to a thickness of 45 μm, and the coating film of the adhesive composition is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C. , when the coating film is foamed and cured to form a foam layer, in a cross section parallel to the thickness direction of the foam layer, the length in the thickness direction of the foam layer is the value of the thickness of the foam layer - 6 μm. The number of bubbles is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. The number of bubbles is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0.

Note that when applying the adhesive composition to one side of the support, a support having a smooth surface is used, and the adhesive composition is applied to the smooth surface of the support. The support is not particularly limited as long as it has a smooth surface and heat resistance, and for example, a glass substrate, a resin substrate, etc. can be used.

Furthermore, for the adhesive composition, the thickness direction of the foam layer is perpendicular to the plane direction of the support. Further, the direction perpendicular to the thickness direction of the foam layer is the plane direction of the support.

II. Second Embodiment of Adhesive Composition A second embodiment of the adhesive composition in the present disclosure is an adhesive composition containing a curable adhesive and a foaming agent, the curable adhesive comprising: The adhesive composition is a thermosetting adhesive, and the foaming agent is a thermally expandable microcapsule. When the coating film is foamed and cured by heating the film at the maximum foaming temperature of the foaming agent ±20°C for 15 minutes to form a foam layer, in a cross section parallel to the thickness direction of the foam layer, The number of cells having a length of 100 μm or more in the thickness direction of the foam layer is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.

In the adhesive composition of this embodiment, as described in the section of the second embodiment of the above-mentioned article, the adhesive composition is applied to one surface of the support at a predetermined thickness, and the adhesive composition is When a foam layer is formed by foaming and curing the coating film by heating the coating film at a predetermined temperature for a predetermined time, the thickness of the foam layer is measured in a cross section parallel to the thickness direction of the foam layer. When the number of bubbles having a length of 100 μm or more is equal to or less than a predetermined value per predetermined length in the direction perpendicular to the thickness direction of the foam layer, poor adhesion can be suppressed. Therefore, it is possible to improve adhesiveness.

In this embodiment, the adhesive composition is applied to one side of the support to a thickness of 45 μm, and the coating film of the adhesive composition is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C. When a foam layer is formed by foaming and curing the coating film, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more in the cross section parallel to the thickness direction of the foam layer is Less than 7 pieces per 4 mm length in the direction perpendicular to the thickness direction of the body layer. The number of bubbles is preferably 3 or less, more preferably 2 or less, even more preferably 1 or less, and particularly preferably 0.

The support may be the same as in the first embodiment.

Note that the present disclosure is not limited to the above embodiments. The above-mentioned embodiments are illustrative, and any configuration that has substantially the same technical idea as the claims of the present disclosure and provides similar effects is the present invention. within the technical scope of the disclosure.

[Examples 1 to 5 and Comparative Examples 1 to 2]
First adhesive compositions 1 to 7 and second adhesive compositions 1 to 7 having the compositions shown in Table 1 below were prepared using the following materials.

・Acrylic resin: PMMA-PBuA-PMMA (acrylamide group in part), Tg: -20°C, 120°C, Mw: 150,000
・Epoxy resin A: Bisphenol A novolac type, solid at room temperature, softening temperature: 70°C, epoxy equivalent: 210g/eq, Mw: 1300, melt viscosity at 150°C: 0.5Pa・s
・Epoxy resin B: BPA phenoxy type, solid at room temperature, softening temperature: 110°C, epoxy equivalent: 8000g/eq, Mw: 50,000
・Epoxy resin C: bisphenol A type, liquid at room temperature, epoxy equivalent: 184 to 194 g/eq
・Epoxy resin D: Diaminodiphenylmethane type, high viscosity liquid, epoxy equivalent: 110 to 130 g/eq
・Epoxy resin E: silicone modification, epoxy equivalent: 1200 g/mol
・Curing agent A: Phenol formaldehyde polycondensate, softening point 80°C, hydroxyl equivalent 104g/mol
・Curing agent B: α-(hydroxy (or dihydroxy) phenylmethyl)-ω-hydropoly[biphenyl-4,4'-diylmethylene (hydroxy (or dihydroxy) phenylene methylene)]
・Curing catalyst: 2-phenyl-4,5-dihydroxymethylimidazole, average particle size: 3 μm, melting point: 230°C, reaction initiation temperature 145°C to 155°C, active area 155°C to 173°C (manufactured by Shikoku Kasei Kogyo Co., Ltd., 2PHZ-PW)
・Silane coupling agent: 3-glycidoxypropyltrimethoxysilane

・Blowing agent A: thermally expandable microcapsules, average particle size 10 μm to 16 μm, expansion start temperature 123°C to 133°C, maximum expansion temperature 168°C to 178°C, core: hydrocarbon, shell: thermoplastic polymer, blowing agent B: Thermally expandable microcapsules, average particle size 18 μm to 24 μm, expansion start temperature 120°C to 130°C, maximum expansion temperature 175°C to 190°C, core: hydrocarbon, shell: thermoplastic polymer, blowing agent C: heat Expandable microcapsules, average particle size 18 μm to 24 μm, expansion start temperature 123°C to 133°C, maximum expansion temperature 180°C to 195°C, core: hydrocarbon, shell: thermoplastic polymer, solvent: methyl ethyl ketone

As a separator, a release film (PET separator, manufactured by Nipper Co., Ltd., PET 50 x 1-J2, thickness 50 μm) was used, and the second adhesive composition was applied to the release-treated surface of the release film after coating and drying. It was applied using an applicator so that the thickness was 45 μm. Thereafter, it was dried in an oven at 100° C. for 3 minutes to form a second adhesive layer.

As a base material, polyethylene naphthalate (PEN film, manufactured by Toyobo Film Solutions Co., Ltd., Teonex Q51, thickness 25 μm) was used. The first adhesive composition was applied using an applicator so that the thickness after drying was 45 μm. Thereafter, it was dried in an oven at 100° C. for 3 minutes to form a first adhesive layer.

Next, the surface of the second adhesive layer of the laminate having the separator and the second adhesive layer was laminated onto the surface of the base material of the laminate having the base material and the first adhesive layer. Thereby, a foamable adhesive sheet was obtained in which the first adhesive layer, the base material, the second adhesive layer, and the separator were arranged in this order.

[evaluation]
(1) Adhesion As shown in FIGS. 14(a) and 14(b), two metal plates 41 (cold rolled steel plate SPCC-SD) each having a thickness of 1.6 mm, a width of 25 mm, and a length of 100 mm were prepared. Spacers 42 were arranged at one end of one of the metal plates 41 at a predetermined interval. The thickness of the spacer 42 was approximately 370 μm (thickness obtained by stacking two sheets of Kapton tape P-221 manufactured by Nitto Denko Corporation and one sheet of fluororesin adhesive tape 8410 manufactured by Teraoka Seisakusho). Further, the foam adhesive sheet was cut into a size of 12.5 mm x 25 mm. When the foamable adhesive sheet had a separator, the separator was removed. Next, the foam adhesive sheet 10 was placed between the spacers 42, and another metal plate 41 was placed so that one tip overlapped with the other metal plate 41, and was fixed with a clip to obtain a test piece. Thereafter, the test piece was placed in a thermal oven, and the temperature was raised from room temperature to a predetermined temperature in 13 minutes, and held for 20 minutes to foam and harden the first adhesive layer and the second adhesive layer of the foamable adhesive sheet 10. At this time, the heating temperatures were 150°C, 160°C, 170°C, 180°C, 190°C, and 200°C.

The shear strength (adhesive strength) of the heated test piece was measured using a tensile tester Tensilon RTF1350 (manufactured by A&D Co., Ltd.) in accordance with JIS K6850. The measurement conditions were a tensile speed of 10 mm/min and a temperature of 23°C. Tables 2 and 3 show the heating temperature and adhesive strength when the adhesive strength was the highest among the adhesive strengths at each heating temperature.

(2) Observation of air bubbles A test piece was prepared by bonding the surface of the first adhesive layer of the foamable adhesive sheet onto a glass substrate so that it protruded by about 1 mm. The test piece is placed in a thermal oven, the temperature is raised from room temperature to a predetermined temperature in 13 minutes, and held for 15 minutes, thereby foaming and hardening the first adhesive layer and the second adhesive layer of the foamable adhesive sheet 10. An adhesive sheet having a cured adhesive layer, a base material, and a second cured adhesive layer in this order was obtained. At this time, the heating temperature was the heating temperature at which the adhesive strength was the highest among the adhesive strengths at each heating temperature in the above adhesive strength measurement.

In order to clearly observe the cross section, the part of the adhesive sheet that protruded from the edge of the glass substrate was cut along the edge of the glass substrate with a trimming blade. The cut cross section was fixed so that it could be observed vertically, and bubbles were observed using an optical microscope (digital microscope VHX-2000, manufactured by Keyence Corporation). Then, for each cured adhesive layer, the number of bubbles whose length was equal to or greater than the thickness of the cured adhesive layer (foam layer) - 6 μm was counted in a 4 mm square field of view. The number of bubbles was the average value of the number of bubbles at three randomly selected locations.

In Examples 1 to 5, when the first adhesive layer and the second adhesive layer of the foamable adhesive sheet were respectively foamed and cured to form the first cured adhesive layer and the second cured adhesive layer, the first cured adhesive layer and the second cured adhesive layer In the cured adhesive layer, the predetermined number of bubbles per predetermined length was less than 7, particularly 3 or less, and the adhesiveness was good. On the other hand, in Comparative Examples 1 to 3, when the first adhesive layer and the second adhesive layer of the foamable adhesive sheet were respectively foamed and cured to form the first cured adhesive layer and the second cured adhesive layer, the first cured adhesive In the layer and the second cured adhesive layer, the number of predetermined bubbles per predetermined length was large, and the adhesion was poor.

In the present disclosure, for example, the following inventions are provided.
[1]
An article having a first member, a second member, and an adhesive member disposed between the first member and the second member,
The adhesive member has at least a cured adhesive layer,
The cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent,
In a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is equal to or greater than the thickness of the foam layer - 6 μm is determined by the number of cells in the foam layer. An article having less than 7 pieces per 4 mm length in the direction perpendicular to the thickness direction.
[2]
An article having a first member, a second member, and an adhesive member disposed between the first member and the second member,
The adhesive member has at least a cured adhesive layer,
The cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent,
In a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is 4 mm in the direction perpendicular to the thickness direction of the foam layer. Articles having fewer than 7 pieces per length.
[3]
The adhesive member has a first cured adhesive layer and a second cured adhesive layer,
The article according to [1] or [2], wherein at least one of the first cured adhesive layer and the second cured adhesive layer is the foam layer.
[4]
The article according to [3], wherein the first cured adhesive layer and the second cured adhesive layer are the foam layers.
[5]
A method for manufacturing an article using a foamable adhesive sheet having at least an adhesive layer, the method comprising:
The adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent,
a step of arranging the foamable adhesive sheet between the first member and the second member;
an adhesion step of foaming and curing the foaming agent-containing adhesive layer of the foamable adhesive sheet to form a foam layer, and adhering the first member and the second member;
The foam curing conditions in the bonding step are such that, in a cross section parallel to the thickness direction of the foam layer, the length in the thickness direction of the foam layer is the thickness of the foam layer - 6 μm. A method for manufacturing an article, wherein the number of bubbles is set to be less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.
[6]
A method for manufacturing an article using a foamable adhesive sheet having at least an adhesive layer, the method comprising:
The adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent,
a step of arranging the foamable adhesive sheet between the first member and the second member;
an adhesion step of foaming and curing the foaming agent-containing adhesive layer of the foamable adhesive sheet to form a foam layer, and adhering the first member and the second member;
In the cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is set to the foam curing conditions in the bonding step. A method for producing an article, wherein the number of pieces is set to be less than 7 per 4 mm in the direction perpendicular to the thickness direction of the body layer.
[7]
The foamable adhesive sheet has a first adhesive layer and a second adhesive layer,
The method for producing an article according to [5] or [6], wherein at least one of the first adhesive layer and the second adhesive layer is the foaming agent-containing adhesive layer.
[8]
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
The method for manufacturing an article according to any one of [5] to [7], wherein the heating temperature in the bonding step is within ±20° C. of the maximum foaming temperature of the foaming agent.
[9]
A foamable adhesive sheet having at least an adhesive layer,
The adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent,
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
When the foamable adhesive sheet is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C to foam and cure the foaming agent-containing adhesive layer to form a foam layer, the thickness direction of the foam layer is In the cross section parallel to A foamable adhesive sheet having less than 7 pieces per 4 mm length.
[10]
A foamable adhesive sheet having at least an adhesive layer,
The adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent,
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
When the foamable adhesive sheet is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C to foam and cure the foaming agent-containing adhesive layer to form a foam layer, the thickness direction of the foam layer is In a cross section parallel to , the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. , foam adhesive sheet.
[11]
having a first adhesive layer and a second adhesive layer,
The foamable adhesive sheet according to [9] or [10], wherein at least one of the first adhesive layer and the second adhesive layer is the foaming agent-containing adhesive layer.
[12]
The foamable adhesive sheet according to [11], wherein the first adhesive layer and the second adhesive layer are the foaming agent-containing adhesive layers.
[13]
The foamable adhesive sheet according to [11] or [12], wherein the first adhesive layer has a tack of 0 gf or more and less than 10 gf, and the second adhesive layer has a tack of 10 gf or more and 400 gf or less.
[14]
An adhesive composition comprising a curable adhesive and a foaming agent, the adhesive composition comprising:
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
The adhesive composition is applied to one side of the support to a thickness of 45 μm, and the coating film of the adhesive composition is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C. When a foam layer is formed by foaming and curing the membrane, in a cross section parallel to the thickness direction of the foam layer, the length of the foam layer in the thickness direction is equal to the thickness of the foam layer - 6 μm. The adhesive composition has a number of bubbles equal to or greater than the value of less than 7 per 4 mm length in a direction perpendicular to the thickness direction of the foam layer.
[15]
An adhesive composition comprising a curable adhesive and a foaming agent, the adhesive composition comprising:
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
The adhesive composition is applied to one side of the support to a thickness of 45 μm, and the coating film of the adhesive composition is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C. When a foam layer is formed by foaming and curing the film, in a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is as follows. An adhesive composition having less than 7 pieces per 4 mm length in a direction perpendicular to the thickness direction of the foam layer.

1... Adhesive layer 1a... First adhesive layer 1b... Second

adhesive layer

5, 5a, 5b, 15, 15a, 15b... Foam layer 11... Cured adhesive layer 11a... First cured adhesive layer 11b... Second cured adhesive layer 12... Base material 13a... First intermediate layer 13b... Second intermediate layer 10... Foamable adhesive sheet 20a... First member 20b... Second member 30... Adhesive member 100... Article

Claims

An article having a first member, a second member, and an adhesive member disposed between the first member and the second member,
the adhesive member has at least a cured adhesive layer,
The cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent,
In a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is equal to or greater than the value of the thickness of the foam layer - 6 μm is determined by the number of cells in the foam layer. An article having less than 7 pieces per 4 mm length in the direction perpendicular to the thickness direction.
An article having a first member, a second member, and an adhesive member disposed between the first member and the second member,
the adhesive member has at least a cured adhesive layer,
The cured adhesive layer is a foam layer containing a foamed cured product of an adhesive composition containing a curable adhesive and a foaming agent,
In a cross section parallel to the thickness direction of the foam layer, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is 4 mm in the direction perpendicular to the thickness direction of the foam layer. Articles having fewer than 7 pieces per length.
The adhesive member has a first cured adhesive layer and a second cured adhesive layer,
3. The article of claim 1 or claim 2, wherein at least one of the first cured adhesive layer and the second cured adhesive layer is the foam layer.
4. The article of claim 3, wherein the first cured adhesive layer and the second cured adhesive layer are the foam layers.
A method for manufacturing an article using a foamable adhesive sheet having at least an adhesive layer, the method comprising:
The adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent,
a step of arranging the foamable adhesive sheet between a first member and a second member;
an adhesion step of foaming and curing the foaming agent-containing adhesive layer of the foamable adhesive sheet to form a foam layer, and adhering the first member and the second member;
The foam curing conditions in the bonding step are such that, in a cross section parallel to the thickness direction of the foam layer, the length in the thickness direction of the foam layer is the thickness of the foam layer - 6 μm. A method for manufacturing an article, wherein the number of bubbles is set to be less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer.
A method for manufacturing an article using a foamable adhesive sheet having at least an adhesive layer, the method comprising:
The adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent,
arranging the foam adhesive sheet between the first member and the second member;
an adhesion step of foaming and curing the foaming agent-containing adhesive layer of the foamable adhesive sheet to form a foam layer, and adhering the first member and the second member;
and the foam curing conditions in the bonding step are such that the number of cells whose length in the thickness direction of the foam layer is 100 μm or more in a cross section parallel to the thickness direction of the foam layer is A method for producing an article, wherein the number of pieces is set to be less than 7 per 4 mm in the direction perpendicular to the thickness direction of the body layer.
The foamable adhesive sheet has a first adhesive layer and a second adhesive layer,
The method for manufacturing an article according to claim 5 or 6, wherein at least one of the first adhesive layer and the second adhesive layer is the foaming agent-containing adhesive layer.
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
The method for manufacturing an article according to claim 5 or 6, wherein the heating temperature in the bonding step is within ±20° C. of the maximum foaming temperature of the foaming agent.
A foamable adhesive sheet having at least an adhesive layer,
The adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent,
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
When the foamable adhesive sheet is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C to foam and harden the foaming agent-containing adhesive layer to form a foam layer, the thickness direction of the foam layer is In a cross section parallel to , the number of cells whose length in the thickness direction of the foam layer is equal to or greater than the value of the thickness of the foam layer - 6 μm is in the direction perpendicular to the thickness direction of the foam layer. A foamable adhesive sheet having less than 7 pieces per 4 mm length.
A foamable adhesive sheet having at least an adhesive layer,
The adhesive layer is a foaming agent-containing adhesive layer containing a curable adhesive and a foaming agent,
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
When the foamable adhesive sheet is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C to foam and harden the foaming agent-containing adhesive layer to form a foam layer, the thickness direction of the foam layer is In a cross section parallel to , the number of cells whose length in the thickness direction of the foam layer is 100 μm or more is less than 7 per 4 mm length in the direction perpendicular to the thickness direction of the foam layer. , foam adhesive sheet.
having a first adhesive layer and a second adhesive layer,
The foamable adhesive sheet according to claim 9 or 10, wherein at least one of the first adhesive layer and the second adhesive layer is the foaming agent-containing adhesive layer.
The foamable adhesive sheet according to claim 11, wherein the first adhesive layer and the second adhesive layer are the foaming agent-containing adhesive layers.
The foamable adhesive sheet according to claim 11, wherein the first adhesive layer has a tack of 0 gf or more and less than 10 gf, and the second adhesive layer has a tack of 10 gf or more and 400 gf or less.
An adhesive composition comprising a curable adhesive and a foaming agent, the adhesive composition comprising:
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
The adhesive composition is applied to one side of the support to a thickness of 45 μm, and the coating film of the adhesive composition is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C. When a foam layer is formed by foaming and curing the membrane, in a cross section parallel to the thickness direction of the foam layer, the length in the thickness direction of the foam layer is the thickness of the foam layer - 6 μm. The adhesive composition has a number of bubbles equal to or greater than the value of less than 7 per 4 mm length in a direction perpendicular to the thickness direction of the foam layer.
An adhesive composition comprising a curable adhesive and a foaming agent, the adhesive composition comprising:
The curable adhesive is a thermosetting adhesive, the foaming agent is a thermally expandable microcapsule,
The adhesive composition is applied to one side of the support to a thickness of 45 μm, and the coating film of the adhesive composition is heated for 15 minutes at the maximum foaming temperature of the foaming agent ±20°C. When a foam layer is formed by foaming and curing the membrane, the number of cells whose length in the thickness direction of the foam layer is 100 μm or more in a cross section parallel to the thickness direction of the foam layer is An adhesive composition having less than 7 pieces per 4 mm length in a direction perpendicular to the thickness direction of the foam layer.