JP7396335B2 - Method for manufacturing foam adhesive sheets and articles - Google Patents

Description

The present disclosure relates to a foamable adhesive sheet and a method of manufacturing an article using the same.

Adhesives for bonding members together are widely used in various fields. For example, an adhesive is used when fixing one member to a hole, groove, etc. of the other member. Specifically, in an embedded magnet type motor, an adhesive is used to fix a permanent magnet in a hole in a core.

Liquid adhesives are the mainstream adhesive used in motors. However, in the case of liquid adhesives, there are problems in that uneven coating, protrusion, dripping, etc. occur, which complicates the bonding process.

On the other hand, in recent years, it has been proposed to use an adhesive sheet containing a foaming agent (foamable adhesive sheet) instead of a liquid adhesive.

For example, Patent Document 1 describes a part (c1-1) constituting an adherend (C1) and another part (c1-2) constituting the adherend (C1) or another adherend (C2). ), wherein the adhesive tape has an adhesive layer (B) on one side of the adhesive layer (A), either directly or via another layer. In the adhesive tape, the expansion coefficient in the thickness direction of the adhesive layer (A) after the adhesive tape is left in an environment at 130° C. for 1 hour [thickness of the adhesive layer (A) after being left] /thickness of the adhesive layer (A) before standing]×100 is 200% or more, and the expansion coefficient in the thickness direction of the adhesive layer (B) [the adhesive layer (after the above standing) B) thickness/thickness of the adhesive layer (B) before leaving] x 100 is 120% or less, and the adhesive layer (A) contains a thermosetting resin and a thermally expandable capsule. A layer formed using a composition, wherein the adhesive layer (B) is a thermosetting adhesive layer or a pressure-sensitive adhesive layer, and the adhesive layer (A) constituting the adhesive tape , the step of adhering the part (c1-1) constituting the adherend (C1) in advance [1], and stimulating and expanding at least the adhesive layer (A) to form the adhesive tape. Disclosed is a method for manufacturing an article, comprising a step [2] of bonding the adhesive layer (B) and a portion (c1-2) constituting the adherend (C1) or the adherend (C2). has been done.

Further, for example, Patent Document 2 discloses a method for manufacturing an article in which a gap between an adherend (C1) and an adherend (C2) is adhered via an expanded material of an adhesive tape. has a heat-expandable adhesive layer (A), the heat-expandable adhesive layer (A) contains an adhesive composition (a) and a heat-expandable capsule, and the content of the heat-expandable capsule is is 3 to 100 parts by mass based on 100 parts by mass of the total solid components of the adhesive composition (a), and the adhesive composition (a) contains a thermoplastic resin, and the temperature of the thermoplastic resin is 70°C to The storage elastic modulus measured by a dynamic viscoelastic spectrum at 1 Hz in the range of 120° C. is in the range of 1.0×10 ² Pa to 1.0×10 ⁷ Pa, and the thermally expandable adhesive layer (A ) has an adhesive force of 0.5 N/20 mm or more, and the thermally expandable adhesive layer (A) of the above adhesive tape is pasted on the part (c1-1) constituting the adherend (C1). step [1] of heating the thermally expandable adhesive layer (A) at a temperature of 50°C to 120°C, the heating causes the thermally expandable adhesive layer (A) to expand and Step [3] of forming an expandable adhesive layer (A1), and a step [3] in which the thermally expandable adhesive layer (A1) or the adhesive layer (B) constituting the adhesive tape is formed on the adherend (C1). A method for manufacturing an article is disclosed, which includes a step [4] of attaching the article to another part (c1-2) or another adherend (C2) constituting the article.

Patent No. 6274540 Japanese Patent Application Publication No. 2018-203863

For example, when fixing another member to a hole or groove of one member, as described in Patent Document 1 and Patent Document 2, a foam adhesive sheet is pasted on the other member and temporarily fixed, and one The two members can be adhesively fixed by placing one member to which a foamable adhesive sheet is pasted in the hole or groove of the member, and then foaming and curing the foamable adhesive sheet.

In the adhesive fixing method as described above, the adhesiveness (tack) of the foam adhesive sheet is used to attach the foam adhesive sheet to the other member and temporarily fix the member. However, if the adhesiveness of the foamable adhesive sheet is high, there is a problem in that the ease of inserting one member to which the foamable adhesive sheet is pasted into a hole or groove of the other member is reduced.

Further, in the foamable adhesive sheet, the adhesive layer containing the foaming agent can be formed by, for example, applying an adhesive composition containing the foaming agent and drying it. At this time, as the drying temperature increases, the melt viscosity of the resin component contained in the adhesive composition tends to decrease. If the melt viscosity of the resin component decreases significantly, it may become difficult to form a film. Therefore, when forming the adhesive layer, it is dried at a low temperature for a long time to suppress a significant decrease in the melt viscosity of the resin component and to enable film formation. However, if the drying temperature is low, there will be a large amount of residual solvent, and if the drying time is long, the production efficiency of the foamable adhesive sheet will decrease.

The present disclosure has been made in view of the above circumstances, and its main purpose is to provide a foamable adhesive sheet that has excellent adhesion to members and insertability, and has good production efficiency.

One embodiment of the present disclosure is a foamable adhesive sheet having a first adhesive layer and a second adhesive layer disposed on one side of the first adhesive layer, the first adhesive layer and the second adhesive layer disposed on one side of the first adhesive layer. The second adhesive layer contains a curable adhesive, at least one of the first adhesive layer and the second adhesive layer further contains a foaming agent, and the tack of the first adhesive layer is 0 gf or more. , less than 10gf, the tack of the second adhesive layer is 10gf or more and 400gf or less, and the peak value of loss tangent (tan δ) of the second adhesive layer is 100°C or more and 180°C or less. Provides adhesive sheets.

Another embodiment of the present disclosure includes an arrangement step of arranging the above-described foamable adhesive sheet between the first member and the second member, and foaming and curing the above-mentioned foamable adhesive sheet. A method of manufacturing an article is provided, which includes a bonding step of bonding two members.

The foamable adhesive sheet according to the present disclosure has excellent adhesion to members and insertability, and has the advantage of good production efficiency.

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. 2 is a process diagram illustrating a method for manufacturing a foamable adhesive sheet according to the present disclosure. FIG. 2 is a process diagram illustrating a method for manufacturing a foamable adhesive sheet according to the present disclosure. FIG. 2 is a process diagram illustrating a method for manufacturing a foamable adhesive sheet according to 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. 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 foamable adhesive sheet and the method for manufacturing an article using the same according to the present disclosure will be described in detail.

A. Foamable Adhesive Sheet The foamable adhesive sheet in the present disclosure is a foamable adhesive sheet having a first adhesive layer and a second adhesive layer disposed on one side of the first adhesive layer, the foamable adhesive sheet as described above. The first adhesive layer and the second adhesive layer contain a curable adhesive; at least one of the first adhesive layer and the second adhesive layer further contains a foaming agent; The tack is 0 gf or more and less than 10 gf, the tack of the second adhesive layer is 10 gf or more and 400 gf or less, and the peak value of the loss tangent (tan δ) of the second adhesive layer is 100° C. or more and 180° C. It is as follows.

1 and 2 are schematic cross-sectional views illustrating a foamable adhesive sheet according to the present disclosure. The foamable adhesive sheet 10 in FIG. 1 has a first adhesive layer 1 and a second adhesive layer 2 disposed on one side of the first adhesive layer 1. The foamable adhesive sheet 10 in FIG. 2 has a first adhesive layer 1 and a second adhesive layer 2 disposed on one side of the first adhesive layer 1. A base material 3 is further provided between the layers 2. The first adhesive layer 1 and the second adhesive layer 2 contain a curable adhesive, and at least one of the first adhesive layer 1 and the second adhesive layer 2 further contains a foaming agent. Further, the tack of the first adhesive layer 1 and the tack of the second adhesive layer 2 are each within a predetermined range, and the peak value of the loss tangent (tan δ) of the second adhesive layer 2 is within a predetermined range.

In the present disclosure, by setting the tack of the second adhesive layer within a predetermined range, the second adhesive layer can have good adhesion to the member. Specifically, when adhering and fixing another member to a hole or groove of one member, the surface of the second adhesive layer of the foam adhesive sheet is pasted to the other member, and the hole or groove of one member is fixed. In the case where the other member to which the foamable adhesive sheet is pasted is inserted into the groove or the like, and then the foamable adhesive sheet is foamed and cured to bond one member and the other member, the second adhesive layer By having the tack of the second adhesive layer within a predetermined range, the surface of the second adhesive layer of the foam adhesive sheet can be attached to the other member using the tack of the second adhesive layer, and the second adhesive layer to the member can be attached to the other member. can improve adhesion. Thereby, when inserting the other member to which the foamable adhesive sheet is attached into a hole or groove of one member, peeling or displacement of the foamable adhesive sheet can be suppressed.

Further, in the present disclosure, since the tack of the second adhesive layer is within a predetermined range, the second adhesive layer can have good reworkability. Therefore, for example, in the adhesive fixing method described above, when attaching the surface of the second adhesive layer of the foam adhesive sheet to one member using the tack of the second adhesive layer, the displacement of the foam adhesive sheet is prevented. Can be fixed.

Further, in the present disclosure, since the tack of the first adhesive layer is less than or equal to a predetermined value, the first adhesive layer can be made substantially non-adhesive (tack-free), and the first adhesive layer has good slip properties. It can be an adhesive layer. Therefore, for example, in the adhesive fixing method described above, when inserting the other member to which the foam adhesive sheet is pasted into the hole or groove of one member, the other member to which the foam adhesive sheet is pasted is The member can be inserted smoothly and insertability can be improved. Thereby, peeling and displacement of the foamable adhesive sheet can be suppressed. In addition, in the adhesive fixing method described above, when aligning the members by moving the other member relative to the other member, it is necessary to insert the other member into the hole or groove of one member. The other member can be smoothly moved relative to the other member, and alignment can be easily performed.

Furthermore, in the present disclosure, the tack of the first adhesive layer is less than or equal to a predetermined value, and the first adhesive layer is substantially non-adhesive (tack-free), so that it has good sliding properties and is resistant to blocking. The first adhesive layer can also have good properties. Therefore, the handleability of the foamable adhesive sheet can also be improved.

In addition, in the present disclosure, as described above, the second adhesive layer has excellent adhesion to the member, and the first adhesive layer has excellent slipperiness, so that peeling and misalignment of the foam adhesive sheet can be avoided. 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. Therefore, by using the foamable adhesive sheet of the present disclosure, it is possible to realize adhesion with high adhesive strength, high reliability, and high quality.

Further, in the present disclosure, since the peak value of tan δ of the second adhesive layer is equal to or higher than a predetermined value, film formation is possible even if the second adhesive layer is dried at high temperature, and residual solvent can be reduced. At the same time, the second adhesive layer can be formed efficiently. Therefore, the production efficiency of foamable adhesive sheets can be improved. In addition, since the peak value of tan δ of the second adhesive layer is below a predetermined value, fluidity of the second adhesive layer can be ensured when the foamable adhesive sheet is heated, and it is possible to follow the adhesive surface of the member. It is possible to ensure sex. Therefore, the adhesiveness of the foamable adhesive sheet after foaming and curing can be improved.

In general, as the peak value of tan δ of the adhesive layer increases, the tack of the adhesive layer tends to decrease. In the present disclosure, by setting the peak value of tan δ of the second adhesive layer within a predetermined range, film formability, tackiness, and fluidity during heating can be balanced.

Further, in the present disclosure, since the tack of the second adhesive layer is within a predetermined range, for example, when the second adhesive layer is formed by a transfer method, lifting of the second adhesive layer can be suppressed. can. Furthermore, as described later, when the second separator is arranged on the side of the second adhesive layer opposite to the first adhesive layer, the tack of the second adhesive layer is within a predetermined range. , the second separator can be easily peeled off, and workability can be improved.

Here, "adhesion" is a concept included in "adhesion". A distinction is sometimes made in that adhesion is used to mean a temporary adhesion phenomenon, while 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.

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

1. First Adhesive Layer (1) Characteristics of First Adhesive Layer In the present disclosure, the tack of the first adhesive layer is 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 (tack-free), and the first adhesive layer has good slip properties and anti-blocking properties. can do.

Here , the tack of the first adhesive layer can be measured by a probe tack test. As the probe tack tester, for example, a tacking tester "TAC-II" manufactured by RHESCA can be used. The details of the method for measuring the tack of the first adhesive layer will be described in the Examples section below.

In the present disclosure, the tack of the first adhesive layer can be controlled within a predetermined range by, for example, adjusting the composition of the first adhesive layer. Specifically, in the first adhesive layer containing an epoxy resin and a hardening agent, the tackiness of the first adhesive layer can be improved by using an epoxy resin that is solid at room temperature or by using a hardening agent that is solid at room temperature. can be lowered. In addition, the tackiness of the first 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 in the first adhesive layer containing an epoxy resin and a curing agent. be able to. For example, the first adhesive layer contains multiple types of epoxy resins having different softening temperatures, that is, the first adhesive layer contains one epoxy resin and the first epoxy resin with a softening temperature of 25°C or higher, and By containing another epoxy resin whose softening temperature is 10° C. or more higher than the softening temperature of the first adhesive layer, the adhesiveness of the first adhesive layer can be reduced. Further, for example, the first adhesive layer may contain a plurality of types of epoxy resins having different weight average molecular weights, that is, the first adhesive layer may contain one epoxy resin and one epoxy resin having a weight average molecular weight of 370 or more, and By containing another epoxy resin having a weight average molecular weight of 300 or more higher than the weight average molecular weight of the epoxy resin, the adhesiveness of the first adhesive layer can be reduced. More specifically, in the first adhesive layer containing an epoxy resin and a curing agent, as described below, the first epoxy resin has a low softening temperature and a low molecular weight, and the first epoxy resin has a high softening temperature and a high molecular weight. By containing the second epoxy resin, the adhesiveness of the first adhesive layer can be reduced. Moreover, in the first adhesive layer containing an epoxy resin and a curing agent, the tackiness of the first adhesive layer can be reduced by containing an acrylic resin that is compatible with the epoxy resin, as described later.

In the present disclosure, the static friction coefficient of the surface of the first adhesive layer opposite to the second adhesive layer is, for example, preferably 0.33 or less, may be 0.30 or less, and may be 0.26 or less. There may be. When the static friction coefficient of the surface of the first adhesive layer is within the above range, the first adhesive layer can have good slip properties. Further, the static friction coefficient may be, for example, 0.16 or more.

Here, the static friction coefficient of the surface of the first adhesive layer can be determined in accordance with JIS K7125, which corresponds to ISO 8295. Note that details of the method for measuring the static friction coefficient of the surface of the first adhesive layer will be described in the Examples section below.

In the present disclosure, the static friction coefficient of the surface of the first adhesive layer can be controlled, for example, by adjusting the composition of the first adhesive layer. Specifically, when the first adhesive layer further contains a foaming agent, the coefficient of static friction on the surface of the first adhesive layer is controlled by the average particle size, content, etc. of the foaming agent contained in the first adhesive layer. can do. More specifically, as the average particle size of the blowing agent increases, the coefficient of static friction on the surface of the first adhesive layer tends to decrease. Furthermore, as the content of the foaming agent increases, the coefficient of static friction on the surface of the first adhesive layer tends to decrease.

In the present disclosure, the arithmetic mean roughness (Ra) of the surface of the first adhesive layer opposite to the second adhesive layer is, for example, preferably 0.3 μm or more, and may be 0.5 μm or more, It may be 0.7 μm or more. When the Ra of the first adhesive layer is within the above range, the first adhesive layer can have good slip properties. Moreover, Ra of the first adhesive layer may be, for example, 1.5 μm or less, 1.3 μm or less, or 1.1 μm or less.

Here, Ra of the first adhesive layer can be measured using a white interferometer. Note that details of the method for measuring Ra of the first adhesive layer will be described in the Examples section below.

In the present disclosure, Ra of the first adhesive layer can be controlled, for example, by adjusting the composition of the first adhesive layer. Specifically, when the first adhesive layer further contains a foaming agent, the Ra of the first adhesive layer can be controlled by the average particle size, content, etc. of the foaming agent contained in the first adhesive layer. can. More specifically, as the average particle size of the foaming agent increases, the Ra of the first adhesive layer tends to increase. Furthermore, as the content of the foaming agent increases, the Ra of the first adhesive layer tends to increase.

(2) Material of first adhesive layer The first adhesive layer in the present disclosure contains a curable adhesive.

(a) Curable Adhesive As the curable adhesive included in the first adhesive layer in the present disclosure, a curable adhesive generally used for the adhesive layer of a foamable adhesive sheet can be used. Examples of the curable adhesive include heat-curable adhesives and photo-curable adhesives. Among these, heat-setting adhesives are preferred. The thermosetting adhesive can be applied even when the member does not have transparency, such as a metal member.

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) Epoxy resin The epoxy resin in the present disclosure 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 the adhesive layer of a foamable adhesive sheet can be used. Among them, 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 softening temperature higher than the first epoxy resin, In addition, it is preferable to contain a second epoxy resin having a weight average molecular weight of 20,000 or more. By using the first epoxy resin and the second epoxy resin in combination, the adhesiveness (tackiness) of the first adhesive layer can be reduced, and a foamable adhesive sheet with good slip properties can be obtained. Furthermore, it is possible to obtain a first adhesive layer with good blocking resistance and adhesiveness after foaming and curing.

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, for example, when a foam adhesive sheet is wound up into a roll, the low molecular weight (low epoxy equivalent) epoxy resins are assimilated with each other, causing blocking. It becomes easier.

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, when only the first epoxy resin is used, the effect of suppressing the occurrence of blocking may be insufficient, or the adhesiveness (tackiness) of the first adhesive layer may become too high. Therefore, by further using a second epoxy resin with 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 improve the effectiveness of the first adhesive layer. Adhesion (tackiness) can be kept low.

(i-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 a first adhesive layer having 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. .

Moreover, 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 later. 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. Mw is a polystyrene equivalent value measured by gel permeation chromatography (GPC).

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. Moreover, if the melt viscosity of the first epoxy resin is too low (if the crystallinity of the first epoxy resin is too high), the adhesiveness (tackiness) of the obtained first adhesive layer may become high. 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. , it is presumed that this is because the Tg of the first adhesive layer decreases. 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 resulting first adhesive layer may decrease. Melt viscosity was determined 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 a method 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 type 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 of 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, the first epoxy resin is preferably a bisphenol A novolac 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.

The content of the first epoxy resin is, for example, 1 part by mass or more, may be 3 parts by mass or more, and 5 parts by mass or more when the resin component contained in the first adhesive layer is 100 parts by mass. The amount may be 10 parts by mass or more, 15 parts by mass or more, or 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, when the resin component contained in the first adhesive layer is 100 parts by mass. 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.

(i-2) Second epoxy resin The second epoxy resin has a higher softening temperature than 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 the softening temperature 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.

The content of the second epoxy resin is, for example, 10 parts by mass or more, may be 15 parts by mass or more, and 20 parts by mass or more when the resin component contained in the first adhesive layer is 100 parts by mass. 25 parts by mass or more, 30 parts by mass or more, 35 parts by mass or more, 40 parts by mass or more, 45 parts by mass or more It may be. 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, when the resin component contained in the first 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 first adhesive layer is, for example, 50% by mass or more, and may be 70% by mass or more, and 90% by mass. % or more, or 100% by mass.

(ii) Acrylic resin When the curable adhesive is an epoxy resin adhesive, the first adhesive layer 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 is easy to improve the toughness of the first adhesive layer. 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 first 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 first adhesive layer, making the interface with the adherend less slippery, which may reduce workability.

The acrylic resin in the present disclosure is compatible with the epoxy resin. Here, the fact that the acrylic resin is compatible with the epoxy resin can be confirmed, for example, when the cross section of the first adhesive layer of the foamable adhesive sheet is observed with a scanning electron microscope (SEM) or a transmission electron microscope (TEM). This can be confirmed by the fact that micron-sized islands are not generated. 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 x 100 μm, or in the case where the average thickness of the first adhesive layer is 100 μm or less, the area is in the range of average thickness x 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 first bonding occurs after the foaming agent has finished foaming. However, by using an acrylic resin with a certain molecular weight, it is possible to prevent the melt viscosity from becoming too low, and shrinkage may 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 first adhesive layer 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 (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 methacrylate-acrylate copolymers include acrylic copolymers such as methyl methacrylate-butyl acrylate-methyl methacrylate (MMA-BA-MMA) copolymers. MMA-BA-MMA copolymers also include block copolymers of polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate (PMMA-PBA-PMMA).

The acrylic copolymer may not have a polar group, or may be a modified product in which the above-mentioned polar group is 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. , a first adhesive layer having 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 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 above-mentioned first polymer portion and second polymer portion includes the above-mentioned MMA-BA-MMA copolymer.

The content of the acrylic resin is, for example, 1 part by mass or more, may be 3 parts by mass or more, or 5 parts by mass or more when the resin component contained in the first adhesive layer is 100 parts by mass. It may be 7 parts by mass or more, or it may be 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 40 parts by mass or less, when the resin component contained in the first adhesive layer is 100 parts by mass. It may be 35 parts by mass or less, or it may be 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.

(iii) Curing Agent As the curing agent in the present disclosure, 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. Further, in the present disclosure, a single curing agent or two or more types of curing agents 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 blocked isocyanates.

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.

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 first 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, 15 parts by mass, when the resin component contained in the first adhesive layer is 100 parts by mass. It is preferable that the amount is less than 100%. On the other hand, when using a phenolic curing agent as a main component, the content of the curing agent is, for example, 5 parts by mass or more, 40 parts by mass, when the resin component contained in the first adhesive layer is 100 parts by mass. It is preferable that the amount is less than 100%. 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.

(b) Foaming agent The first adhesive layer in the present disclosure may or may not contain a foaming agent, but preferably contains a foaming agent. By containing the foaming agent, the surface roughness becomes large, the coefficient of friction becomes small, and the slipperiness becomes even better. Therefore, of the first adhesive layer and the second adhesive layer, it is preferable that the first adhesive layer with low tack contains a foaming agent.

As the foaming agent, a foaming agent that is 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.

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, the reaction will start early, foaming will occur with the resin component having low flexibility and fluidity, and uniform foaming may be difficult to produce. On the other hand, the reaction initiation temperature of the blowing agent is, for example, 210° C. or lower. If the reaction initiation temperature is too high, the resin component may deteriorate.

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.

Examples of the foaming agent include microcapsule foaming agents. It is preferable that the microcapsule type foaming agent has a thermal expansion agent such as a hydrocarbon as a core and a resin such as an acrylonitrile copolymer as a shell.

Further, 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 average particle size of the blowing agent may be, for example, 10 μm or more, 13 μm or more, or 17 μm or more. When the average particle size of the foaming agent is within the above range, the coefficient of static friction on the surface of the first adhesive layer can be reduced, and the first adhesive layer can have good slip properties. Further, the average particle size of the foaming agent is preferably equal to or less than the average thickness of the first adhesive layer, and may be, for example, 44 μm or less, 30 μm or less, or 24 μm or less. .

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 a laser diffraction scattering method. Furthermore, when measuring the average particle size of the foaming agent, the first adhesive layer is dissolved in a solvent to separate the foaming agent. The solvent is not particularly limited as long as it is capable of dissolving components other than the foaming agent contained in the first adhesive layer, and may be used depending on the type of curable adhesive contained in the first adhesive layer. An appropriately selected solvent can be used, for example, a solvent used in the adhesive composition used to form the first adhesive layer. Specifically, methyl ethyl ketone, ethyl acetate, toluene, etc. can be used.

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 3 parts by mass or more when the resin component contained in the first adhesive layer is 100 parts by mass. It may be 4 parts by mass or more, or it may be 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, and may be 15 parts by mass or less, based on 100 parts by mass of the resin component contained in the first adhesive layer. Good too. If the content of the foaming agent is too small, the coefficient of static friction on the surface of the first adhesive layer may become large. Furthermore, 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.

(c) Other components In the case where the curable adhesive is an epoxy resin adhesive, the first adhesive layer in the present disclosure may contain only an epoxy resin and an acrylic resin as resin components; It may further contain a resin. Examples of other resins include urethane resins.

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

The content of the resin component contained in the first 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. good.

The first adhesive layer may contain additives such as a silane coupling agent, a filler, an antioxidant, a light stabilizer, an ultraviolet absorber, a lubricant, a plasticizer, an antistatic agent, a crosslinking agent, a coloring agent, 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.

(3) Structure of the first adhesive layer When the first adhesive layer further contains a foaming agent, the first adhesive layer can be foamed at a foaming ratio of, for example, 4 times or more and 15 times or less. For example, when only the first adhesive layer contains a foaming agent among the first adhesive layer and the second adhesive layer, the foaming ratio may be, for example, 5 times or more, or 7 times or more. Often, it may be 9 times or more. Moreover, in the above case, the expansion ratio may be, for example, 14 times or less, 13 times or less, or 12 times or less. On the other hand, for example, when both of the first adhesive layer and the second adhesive layer contain a foaming agent, the foaming ratio may be, for example, 5 times or more. , may be 6 times or more, or may be 7 times or more. Moreover, in the above case, the expansion ratio may be, for example, 14 times or less, 12 times or less, or 10 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 the first adhesive layer after foaming and curing / Thickness of the first adhesive layer before foaming and curing

The average thickness of the first adhesive layer is not particularly limited, but when the first adhesive layer contains a foaming agent, it is preferably equal to or larger than the average particle size of the foaming agent, for example, 10 μm or more, and 15 μm or more. It may be 20 μm or more. If the first 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 average thickness of the first adhesive layer is, for example, 200 μm or less, may be 150 μm or less, or may be 100 μm or less. If the first adhesive layer is too thick, the surface quality may deteriorate.

Here, the average thickness of the first adhesive layer is the thickness direction of the foam adhesive sheet observed by a transmission electron microscope (TEM), a scanning electron microscope (SEM), or a scanning transmission electron microscope (STEM). This is a value measured from a cross section, and can be the average value of thicknesses at 10 randomly selected locations. Note that the same method can be used for measuring the average thickness of other layers included in the foamable adhesive sheet.

The first 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 first adhesive layer may have an uneven shape such as embossing.

The first adhesive layer can be formed, for example, by applying an adhesive composition containing the above-mentioned curable adhesive and a 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. Second Adhesive Layer (1) Characteristics of Second Adhesive Layer In the present disclosure, the tack of the second adhesive layer is 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 in the adhesive fixing method described above, when attaching the surface of the second adhesive layer of the foam adhesive sheet to the other member using the tack of the second adhesive layer, There is a possibility that the adhesion between the second adhesive layer and the other member will decrease, or when inserting the other member with the foam adhesive sheet pasted into the hole or groove of the other member, the second adhesive layer and the other member may deteriorate. If the foam adhesive sheet peels off or the position of the foam adhesive sheet shifts due to poor adhesion of the other member, the adhesiveness of the first adhesive layer and the second adhesive layer after foam curing may decrease, or the adhesiveness may deteriorate. There is a possibility that variations in strength may occur. Further, the tack of the second adhesive layer is 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, in the adhesive fixing method described above, the tack of the second adhesive layer is used to attach the surface of the second adhesive layer of the foam adhesive sheet to the other member. It may be difficult to correct misalignment of the foam adhesive sheet when pasting the foam adhesive sheet.

Here, the method for measuring the tack of the second adhesive layer can be the same as the method for measuring the tack of the first adhesive layer.

In the present disclosure, the tack of the second adhesive layer can be controlled, for example, by adjusting the composition of the second adhesive layer. Specifically, in the second 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 adhesiveness of the second adhesive layer increases. Tend. In addition, when the second adhesive layer containing an epoxy resin and a curing agent contains an epoxy resin with a low softening temperature or an epoxy resin with a small weight average molecular weight, the adhesiveness of the second adhesive layer tends to increase. There is. Furthermore, by adding a tackifying resin (tackifier) to the second adhesive layer, the tackiness of the second 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 second adhesive layer by adjusting.

In the present disclosure, the peak value of the loss tangent (tan δ) of the second adhesive layer is 100°C or higher, may be 110°C or higher, or may be 120°C or higher. Since the peak value of tan δ of the second adhesive layer is within the above range, it is possible to form a film even if the second adhesive layer is dried at high temperature, reducing residual solvent and efficiently forming the second adhesive layer. can be formed. Further, the peak value of tan δ of the second adhesive layer is 180°C or less, may be 170°C or less, or may be 160°C or less. By having the peak value of tan δ of the second adhesive layer within the above range, fluidity of the second adhesive layer can be ensured when the foamable adhesive sheet is heated, and followability to the adhesive surface of the member can be ensured. be able to. Therefore, the adhesiveness of the foamable adhesive sheet after foaming and curing can be improved.

Here, tan δ of the second adhesive layer can be measured by dynamic viscoelasticity measurement, and is calculated from the following formula.
Loss tangent (tanδ) = loss modulus (E'')/storage modulus (E')
Note that details of the method for measuring tan δ of the second adhesive layer will be described in the Examples section below. Furthermore, when there are multiple peaks of tan δ, the higher temperature was taken as the peak value of tan δ.

In the present disclosure, the peak value of tan δ of the second adhesive layer can be controlled, for example, by adjusting the composition of the second adhesive layer. Specifically, in the second adhesive layer containing an epoxy resin and a curing agent, the tan δ of the second adhesive layer can be increased by incorporating an epoxy resin with a high softening temperature or an epoxy resin with a large weight average molecular weight. The peak value tends to be high.

(2) Material of second adhesive layer The second adhesive layer in the present disclosure contains a curable adhesive.

(a) Curable Adhesive The curable adhesive included in the second adhesive layer in the present disclosure can be the same as the curable adhesive used in the first adhesive layer. Among these, the curable adhesive is preferably an epoxy resin adhesive.

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

(i) Epoxy resin The epoxy resin in the present disclosure can be the same as the epoxy resin used for the first adhesive layer.

As the epoxy resin, an epoxy resin generally used for the adhesive layer of a foamable adhesive sheet can be used.

Examples of the second epoxy resin include aromatic epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, and heterocyclic epoxy resins. Specific examples of the second epoxy resin may be the same as those of the first epoxy resin used in the first adhesive layer.

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

Among these, it is preferable to use, as the epoxy resin, 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.

(ii) Acrylic resin When the curable adhesive is an epoxy resin adhesive, the second adhesive layer may further contain an acrylic resin that is compatible with the epoxy resin. Film formability can be improved.

The acrylic resin can be the same as the acrylic resin used for the first adhesive layer.

(iii) Curing agent The curing agent in the present disclosure can be the same as the curing agent used for the first adhesive layer. Further, as the curing agent, a curing agent that is solid at room temperature or a curing agent that is liquid at room temperature can be used, but from the viewpoint of storage stability, it is preferable to use a curing agent that is solid at room temperature.

(b) Foaming agent The second adhesive layer in the present disclosure may or may not contain a foaming agent, but preferably contains 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 foaming agent may be the same as the foaming agent used for the first adhesive layer.

(c) Other components In the case where the curable adhesive is an epoxy resin adhesive, the second adhesive layer in the present disclosure may contain only an epoxy resin and an acrylic resin as resin components, or may contain other components. It may further contain a resin. Examples of other resins include urethane resins.

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

The content of the resin component contained in the second 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. good.

The second adhesive layer may contain additives as necessary. The additives may be the same as those used in the first adhesive layer.

(3) Configuration of second adhesive layer When the second adhesive layer further contains a foaming agent, the second adhesive layer can be foamed at a foaming ratio of, for example, 1.5 times or more and 12 times or less. For example, when both the first adhesive layer and the second adhesive layer contain a foaming agent among the first adhesive layer and the second adhesive layer, the foaming ratio may be, for example, 2 times or more, or 3 times or more. It may be more than twice as much, or more than 4 times. Moreover, in the above case, the expansion ratio may be, for example, 10 times or less, 9 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.

The average thickness of the second adhesive layer can be the same as the average thickness of the first adhesive layer.

The second adhesive layer may be a continuous layer or a discontinuous layer. Further, the surface of the second adhesive layer may have an uneven shape such as embossing.

The method for forming the second adhesive layer can be the same as the method for forming the first adhesive layer.

3. Base Material The foamable adhesive sheet in the present disclosure may have a base material between the first adhesive layer and the second adhesive layer. When a base material is disposed between the first adhesive layer and the second adhesive layer, the foamable adhesive sheet can be easily handled and worked. On the other hand, if no base material is placed between the first adhesive layer and the second adhesive layer, the overall thickness of the foam adhesive sheet can be reduced, and the foam adhesive sheet can be used even in narrow gaps. can be inserted.

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 surface-treated to improve adhesion with the first adhesive layer and the second adhesive layer.

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

4. Other configurations (1) First intermediate layer and second intermediate layer The foamable adhesive sheet in the present disclosure may have a first intermediate layer between the base material and the first adhesive layer. Further, the foamable adhesive sheet in the present disclosure may have a second intermediate layer between the base material and the second adhesive layer. By arranging the first intermediate layer and the second intermediate layer, it is possible to improve the adhesion of the first adhesive layer and the second adhesive layer to the base material. Furthermore, by arranging the first intermediate layer and the second intermediate layer, for example, when the foam adhesive sheet is bent, stress applied to the bent part can be alleviated, and when the foam adhesive sheet is cut, the stress applied to the bent part can be alleviated. The stress applied to the cut portion can be alleviated. 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 foamable adhesive sheet 10 shown in FIG. Layer 5 is arranged. In addition, although the foamable adhesive sheet 10 has both the first intermediate layer 4 and the second intermediate layer 5 in FIG. 3, it may have only either one.

The foamable adhesive sheet 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 adhesive layer. It may have only the second intermediate layer disposed between the base material and the second adhesive layer, or it may have only the second intermediate layer disposed between the base material and the first adhesive layer, and the base material and the first intermediate layer disposed between the base material and the first adhesive layer. and a second intermediate layer disposed between the second adhesive layer. Among these, it is preferable that the first intermediate layer is disposed between the base material and the first adhesive layer, and that the second intermediate layer is disposed between the base material and the second adhesive layer.

The material included in the first intermediate layer and the second intermediate layer may be any material that can enhance the adhesion between the base material and the first adhesive layer or the second adhesive layer, and can relieve stress. It is not particularly limited, and is appropriately selected depending on the materials of the base material, the first adhesive layer, the second 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 average thickness of the first intermediate layer and the second intermediate layer is not particularly limited, and may be, for example, 0.1 μm or more, 0.5 μm or more, or 1 μm or more. If the first intermediate layer or the second intermediate layer is too thin, the effect of suppressing the peeling of the first adhesive layer or the second adhesive layer from the base material during bending or cutting of the foamable adhesive sheet will not be achieved sufficiently. there is a possibility. On the other hand, the average 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 separator and second separator The foamable adhesive sheet in the present disclosure may have a first separator on the side of the first adhesive layer opposite to the second adhesive layer. Further, the foamable adhesive sheet in the present disclosure may have a second separator on the side of the second adhesive layer opposite to the first adhesive layer.

The first separator and the second separator are not particularly limited as long as they can be peeled off from the first adhesive layer and the second adhesive layer, and have sufficient strength to protect the first adhesive layer and the second adhesive layer. be able to. Examples of the first separator and the second separator include a release film, release paper, and the like. Further, the first separator and the second separator may have a single layer structure or a multilayer structure.

Examples of the single-layer separator include fluororesin films.

Moreover, 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. Among these, it is preferable that the first separator has heavy releasability and the second separator has light releasability. In foamable adhesive sheets, the first adhesive layer is substantially tack-free and the second adhesive layer is tack-free. Therefore, for example, when bonding the rotor and permanent magnets in an embedded magnet type motor, after placing the foam adhesive sheet on the second member, the foam adhesive sheet is placed in the hole of the first member. When inserting a member, attach the second adhesive layer side of the foam adhesive sheet to the second member, and make sure that the first adhesive layer side of the foam adhesive sheet is on the front side. The adhesion between the second member and the foamable adhesive sheet and the insertability of the second member on which the foamable adhesive sheet is placed 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.

5. Foamable Adhesive Sheet The average thickness of the foamable adhesive sheet in the present disclosure is, for example, 10 μm or more, and may be 20 μm or more. On the other hand, the average 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 the present disclosure 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, in the foamable adhesive sheet according to the present disclosure, the surface hardness is increased so that the surface is not damaged even when inserted at high speed.

The foamable adhesive sheet in the present disclosure preferably has high adhesiveness after foaming and curing. The shear strength (adhesive strength) based on JIS K6850 corresponding to ISO 4587 may be, for example, 1.50 MPa or more, 1.80 MPa or more, or 2.10 MPa or more at 23°C. 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 becomes possible to apply it to applications where heat resistance similar to that of automobile engines is required.

The foamable adhesive sheet in the present disclosure preferably has high electrical insulation properties after foaming and curing. The dielectric breakdown voltage based on JIS C2107 corresponding to IEC 60454-2 is preferably 3 kV or more, and more preferably 5 kV or more, for example. When the dielectric breakdown voltage is within the above range, it becomes possible to prevent rust and to be applied around copper wires. Further, the adhesive sheet after foaming and curing preferably has a thermal conductivity of, 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 use of the foamable adhesive sheet in the present disclosure is not particularly limited. The foamable adhesive sheet according to the present disclosure can be used, for example, when bonding two members together by placing the foamable adhesive sheet between two members and then foaming and curing the foamable adhesive sheet. . Among them, the foamable adhesive sheet in the present disclosure is obtained by placing the foamable adhesive sheet on a second member, and then inserting the second member on which the foamable adhesive sheet is placed into the hole of the first member. By foaming and curing, it is preferably used when bonding the first member and the second member.

6. Method for manufacturing a foamable adhesive sheet The method for manufacturing a foamable adhesive sheet in the present disclosure is not particularly limited, and is appropriately selected depending on the layer configuration of the foamable adhesive sheet.

When the foamable adhesive sheet does not have a base material between the first adhesive layer and the second adhesive layer, in the method for manufacturing the foamable adhesive sheet, for example, first, as shown in FIG. An adhesive composition for forming a first adhesive layer is applied on one separator 6 and dried to form a first adhesive layer 1, and as shown in FIG. An adhesive composition for forming a second adhesive layer is applied and dried to form a second adhesive layer 2. Next, as shown in FIG. 4C, the laminate of the first separator 6 and the first adhesive layer 1 and the laminate of the second separator 7 and the second adhesive layer 2 are laminated. As a result, a foamable adhesive sheet is obtained. Note that since the first adhesive layer 1 is substantially non-adhesive (tack-free), the first separator 6 may be peeled off after lamination to form a foamable adhesive sheet.

Furthermore, when the foamable adhesive sheet has a base material between the first adhesive layer and the second adhesive layer, for example, two methods of manufacturing the foamable adhesive sheet can be mentioned.

In the first method for producing a foamable adhesive sheet, for example, first, as shown in FIG. 5(a), a resin composition for forming the first intermediate layer is applied and dried on the base material 3. Thus, the first intermediate layer 4 is formed. Next, as shown in FIG. 5(b), an adhesive composition for forming a first adhesive layer is applied on the first intermediate layer 4 and dried to form the first adhesive layer 1. Further, as shown in FIG. 5(c), an adhesive composition for forming a second adhesive layer is applied on the second separator 7 and dried to form the second adhesive layer 2. Next, as shown in FIG. 5(d), the laminate of the base material 3, the first intermediate layer 4, and the first adhesive layer 1 and the laminate of the second separator 7 and the second adhesive layer 2 are laminated. . As a result, a foamable adhesive sheet is obtained. Note that the formation of the first intermediate layer 4 may be omitted. In this method, since the drying step for the first adhesive layer 1 is performed only once, the foamable adhesive sheet can be efficiently manufactured.

In the second method for manufacturing a foamable adhesive sheet, for example, first, as shown in FIG. 6(a), a resin composition for forming a first intermediate layer is applied to one surface of the base material 3. and dry to form the first intermediate layer 4. Next, as shown in FIG. 6(b), an adhesive composition for forming a first adhesive layer is applied on the first intermediate layer 4 and dried to form the first adhesive layer 1. Next, as shown in FIG. 6(c), a resin composition for forming the second intermediate layer is applied to the other surface of the base material 3 and dried to form the second intermediate layer 5. Next, as shown in FIG. 6(d), an adhesive composition for forming a second adhesive layer is applied on the second intermediate layer 5 and dried to form the second adhesive layer 2. Subsequently, as shown in FIG. 6(e), a second separator 7 is laminated on the second adhesive layer 2. As a result, a foamable adhesive sheet is obtained. Note that the formation of the first intermediate layer 4 may be omitted. Furthermore, the formation of the second intermediate layer 5 may be omitted.

B. Method for manufacturing an article The method for manufacturing an article according to the present disclosure includes a step of arranging the above-described foamable adhesive sheet between a first member and a second member, foaming and hardening the foamable adhesive sheet, and and an adhesion step of adhering the member and the second member.

FIGS. 7(a) to (c) are process diagrams showing an example of a method for manufacturing an article according to the present disclosure. First, as shown in FIG. 7(a), the surface of the second adhesive layer 2 of the foamable adhesive sheet 10 is attached to the second member 20b. Next, as shown in FIG. 7(b), the second member 20b on which the foamable adhesive sheet 10 is placed is inserted into the hole of the first member 20a. Next, as shown in FIG. 7C, the first adhesive layer 1 and the second adhesive layer 2 of the foamable adhesive sheet 10 are foamed and cured, for example, by heating. The first member 20a and the second member 20b are adhered (joined) by the adhesive sheet 13 having the first adhesive layer 11 and the second adhesive layer 12 after foaming and hardening. Thereby, an article 100 is obtained in which the adhesive sheet 13 is placed between the first member 20a and the second member 20b.

FIGS. 8(a) to 8(c) are process diagrams showing other examples of the method for manufacturing an article according to the present disclosure. In FIG. 8(a), foam adhesive sheets are attached to both sides of the second member 20b. Note that the arrangement process and adhesion process are the same as those in FIGS. 7(a) to (c).

Hereinafter, a method for manufacturing an article according to the present disclosure will be described.

1. Foamable Adhesive Sheet In the method for manufacturing an article according to the present disclosure, the above-described foamable adhesive sheet is used as the foamable adhesive sheet.

When the foam adhesive sheet has a first separator and a second separator, when placing the foam adhesive sheet between the first member and the second member, remove the first separator and the second separator from the foam adhesive sheet. Peel off and use.

Note that the details of the foamable adhesive sheet are described in the section "A. Foamable adhesive sheet" above, so the explanation here will be omitted.

2. Arranging Step In the arrangement step of the present disclosure, the method for arranging the foam 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, when the first member has holes or grooves and the second member is placed in the holes or grooves of the first member, and the first member and the second member are fixed by adhesive, foaming 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 adhesive sheet, the foam adhesive sheet is pasted into the holes and grooves of the first member. There is also a method of placing a second member with a foam adhesive in the hole or groove of the first member, and then 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 of affixing the surface of the second adhesive layer of the foamable adhesive sheet, and then arranging the second member in the hole or groove of the first member to which the foamable adhesive sheet is pasted.

3. Adhesion Step In the adhesion step of the present disclosure, examples of the method for foaming and curing the foamable adhesive sheet include heating or light irradiation. Among these, it is preferable to foam and harden 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 appropriately set depending on the type of curable adhesive and foaming agent contained in the first adhesive layer and the second adhesive layer, the type of the base material, and the like. The heating temperature can be, for example, 130°C or higher and 200°C or lower. Further, the heating time can be, for example, 3 minutes or more and 3 hours or less.

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.

[Manufacturing example]
First, adhesive compositions having the compositions shown in Tables 1 and 2 below were prepared. Further, details of each material listed in Tables 1 and 2 are shown below.

・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
・Epoxy resin F: Phenol novolak type, liquid at room temperature, epoxy equivalent: 176 to 178 g/eq

・Curing agent 1: α-(hydroxy (or dihydroxy) phenylmethyl)-ω-hydropoly[biphenyl-4,4'-diylmethylene (hydroxy (or dihydroxy) phenylene methylene)]
・Curing agent 2: 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)
・Curing agent 3: dicyandiamide, particle size: 10 μm or less, melting point: 209°C (DYHARD100SH, manufactured by Evonik Degussa)
・Curing agent 4: Epoxy resin amine adduct (manufactured by Ajinomoto Fine Techno, Amicure MY-H)

・Thermal foaming agent 1: thermally expandable microcapsules, average particle size 7 μm, expansion start temperature 120-145°C, maximum expansion temperature 155-175°C, core: hydrocarbon, shell: thermoplastic polymer ・Thermal foaming agent 2: Thermal expandable microcapsules, average particle size 13 μm, expansion start temperature 123-133°C, maximum expansion temperature 168-178°C, core: hydrocarbon, shell: thermoplastic polymer, thermal foaming agent 3: thermally expandable microcapsules, Average particle size 17 μm, expansion start temperature 120-130°C, maximum expansion temperature 160-170°C, core: hydrocarbon, shell: acrylonitrile copolymer/thermal foaming agent 4: thermally expandable microcapsules, average particle size 20 μm, expansion start temperature 115-125°C, maximum expansion temperature 155-165°C, core: hydrocarbon, shell: thermoplastic polymer, thermal blowing agent 5: thermally expandable microcapsules, average particle size 21 μm, expansion start temperature 130-140°C, maximum Expansion temperature 160-170°C, core: hydrocarbon, shell: acrylonitrile copolymer, thermal foaming agent 6: thermally expandable microcapsules, average particle size 21 μm, expansion start temperature 123-133°C, maximum expansion temperature 180-195°C, core : Hydrocarbon, Shell: Thermoplastic polymer/thermal foaming agent 7: Thermal expandable microcapsules, average particle size 21 μm, expansion start temperature 120-130°C, maximum expansion temperature 175-190°C, core: hydrocarbon, shell: Thermoplastic polymer/thermal foaming agent 8: thermally expandable microcapsules, average particle size 25 μm, expansion start temperature 125-135°C, maximum expansion temperature 165-180°C, core: hydrocarbon, shell: thermoplastic polymer/thermal Foaming agent 9: thermally expandable microcapsules, average particle size 30 μm, expansion start temperature 120-130°C, maximum expansion temperature 160-170°C, core: hydrocarbon, shell: acrylonitrile copolymer, thermally expandable microcapsules, thermally expandable microcapsules 10: thermally expandable microcapsules Capsule, average particle size 41 μm, expansion start temperature 115-125°C, maximum expansion temperature 165-175°C, core: hydrocarbon, shell: acrylonitrile copolymer

・Silane coupling agent: 3-glycidoxypropyltrimethoxysilane ・Antioxidant: Hindered phenolic antioxidant ・Solvent: Methyl ethyl ketone

[Examples 1 to 13]
As a base material, polyethylene naphthalate (PEN film, manufactured by Toyobo Film Solutions Co., Ltd., Teonex Q51, thickness 25 μm) was used. In addition, 15 parts by mass of a curing agent (polyisocyanate) and 0.3 parts by mass of a catalyst (trisdimethylaminomethylphenol) are blended with 100 parts by mass of the polyester polymer, and the solid content is 15% by mass. A resin composition was prepared by diluting with methyl ethyl ketone (MEK) so that The resin composition was applied to one side of the base material using a bar coater, and dried in an oven at 100° C. for 1 minute to form a first intermediate layer having a thickness of 2 μm. Next, the adhesive composition was applied to the surface of the first intermediate layer opposite to the base material using an applicator so that the thickness after application was 45 μm. Thereafter, it was dried in an oven at 100° C. for 3 minutes to form a first adhesive layer.

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

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

[Comparative example 1]
In the same manner as in Example 1, a first intermediate layer and a first adhesive layer were formed on the base material. Next, the adhesive composition was applied to the surface of the substrate opposite to the first intermediate layer using an applicator so that the thickness after application was 45 μm. Thereafter, it was dried in an oven at 100° C. for 3 minutes to form a second adhesive layer. Thereby, a foamable adhesive sheet was obtained in which the first adhesive layer, the first intermediate layer, the base material, and the second adhesive layer were arranged in this order.

[Comparative Examples 2-3]
As the first separator, a release film (PET separator, manufactured by Nipper Co., Ltd., PET 38 x 1-J2, thickness 38 μm) was used, and the adhesive composition was applied to the release-treated surface of the release film after coating. 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 first adhesive layer.

Next, polyethylene naphthalate (PEN film, manufactured by Toyobo Film Solutions Co., Ltd., Teonex Q51, thickness 25 μm) was used as the base material, and the first adhesive of the laminate having the first separator and the first adhesive layer was used as the base material. The sides of the layers were laminated.

Next, a release film (PET separator, manufactured by Nipper Co., Ltd., PET38×1-Q2ASI5, thickness 38 μm) was used as a second separator, and the above adhesive composition was applied to the release-treated surface of the release film. The coating was applied using an applicator so that the thickness after coating was 45 μm. Thereafter, it was dried in an oven at 100° C. for 3 minutes to form a second adhesive layer.

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

[evaluation]
(Tack of first adhesive layer and second adhesive layer)
Regarding the tack of the first adhesive layer, using a tacking tester "TAC-II" manufactured by RHESCA, a cylindrical stainless steel probe with a diameter of 5 mm was placed on the surface of the first adhesive layer of the foam adhesive sheet. At a temperature of 25°C, it was pressed at a load of 10.0 gf and a speed of 30 mm/min, held for 1.0 seconds, and then peeled off at a speed of 30 mm/min, and the load at the time of peeling was measured. This measurement was performed five times, and the average value was taken as the tack.

Similar to the tack of the first adhesive layer, the tack of the second adhesive layer was also measured.

(Friction coefficient of the surface of the first adhesive layer)
The dynamic friction coefficient and static friction coefficient between the first adhesive layer of the foamable adhesive sheet and the metal plate were measured in accordance with JIS K7125. First, a foamable adhesive sheet was cut into a size of 80 mm x 200 mm. Next, the foam adhesive sheet was placed on a rectangular metal plate (SUS plate) placed horizontally, and a sliding piece (63 mm x 63 mm, weight 200 g, The friction force was measured under the conditions of a test speed of 100 mm/min, a test length of 50 mm, a load cell of 10 N, and a temperature of 23° C., and the dynamic friction coefficient and static friction coefficient were calculated. The device used was a friction measuring machine FRICTION TESTER TR-2 manufactured by Toyo Seiki Seisakusho.

(Arithmetic mean roughness Ra of first adhesive layer)
The arithmetic mean roughness Ra of the first adhesive layer was measured using a white interferometer NewView 7300 manufactured by Zygo Co., Ltd. with an observation field of view: 0.55 mm x 0.55 mm and a sampling interval: 0.55 μm.

(Peak value of tan δ of second adhesive layer)
The second separator was peeled off from the laminate of the second separator and second adhesive layer produced above to obtain a single second adhesive layer. Attachment mode: compression mode, frequency: 1 Hz, temperature: Measure the storage modulus (E') and loss modulus (E'') of the second adhesive layer at -20°C to 200°C, heating rate: 10°C/min, and calculate the loss tangent (tanδ). did. In addition, when multiple peaks of tan δ exist, the higher temperature was taken as the peak value of tan δ.

(Foaming ratio)
The foam adhesive sheet was cut into a size of 25 mm x 100 mm, the second separator was peeled off, and the surface of the second adhesive layer of the foam adhesive sheet was attached to a glass plate with a thickness of 1.0 mm. The adhesive sheets were arranged on an aluminum bat with the first adhesive layer facing upward. At this time, when the foamable adhesive sheet had a first separator, the first separator was peeled off. After foaming and curing at 180° C. for 30 minutes, the mixture was cooled at room temperature for 2 hours to obtain a foaming and curing adhesive sheet. Then, the thickness of the adhesive sheet after foaming and curing was measured using a thickness gauge in accordance with JIS Z0237. The foaming ratio was determined by the following formula.
Foaming ratio (times) = {thickness of adhesive sheet after foaming and curing - (thickness of base material + thickness of first intermediate layer)} / (first adhesive layer and first intermediate layer of foamable adhesive sheet before foaming and curing) total thickness of two adhesive layers)

(Adhesiveness after foam curing)
As shown in FIGS. 9(a) and 9(b), two metal plates 31 (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. A spacer 32 (Kapton tape) was placed at one end of one of the metal plates 31 at a predetermined interval. The thickness of the spacer 32 was approximately 280 μm (the thickness of four layers of Kapton tape P-221 manufactured by Nitto Denko Corporation). Next, the foam adhesive sheet 10 is placed between the spacers 32, cut into a size of 12.5 mm x 25 mm, and with the first separator and second separator peeled off if the foam adhesive sheet has a separator. Then, another metal plate 31 was placed so that one tip overlapped with the other metal plate 31, and was fixed with a clip to obtain a test piece. Thereafter, the test piece was placed in a thermal oven and heated at 180° C. for 30 minutes to cure the foamable adhesive sheet 10.

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 or 130°C.

(Slip properties of the first adhesive layer and adhesion of the second adhesive layer during insertion)
A foam adhesive sheet cut into 5.5 cm x 8.0 cm, a hollow cylinder 1 with an outer diameter of 22 mm, a thickness of 1.5 mm, and a length of 60 mm, and an outer diameter of 18 mm, a thickness of 1.0 mm, and a length of 80 mm. A hollow cylinder 2 was prepared. When the foam adhesive sheet has a second separator, the second separator is peeled off, and the surface of the second adhesive layer is pasted on the outer diameter part of the cylinder 2 so that the short side is in the circumferential direction, and the foam adhesive sheet is was placed. When the foamable adhesive sheet had a first separator, the first separator was peeled off. Thereafter, the cylinder 2 was slowly pushed by hand and inserted into the hollow gap of the cylinder 1, and the slipperiness of the first adhesive layer and the adhesion of the second adhesive layer at that time were evaluated. The evaluation criteria were as follows.

- Smoothness of the first adhesive layer A: No catching during insertion.
B: There is a catch during insertion (the first adhesive layer sticks to the cylinder 1, resulting in poor insertion performance).

- Adhesion of the second adhesive layer A: The foamable adhesive sheet does not peel off from the cylinder 2 during insertion.
B: The foamable adhesive sheet peels off from the cylinder 2 when inserted, or the foamable adhesive sheet does not adhere tightly to the cylinder 2 when pasted.

In the foamable adhesive sheets of Examples 1 to 13, the tack of the first adhesive layer and the tack of the second adhesive layer were each within a predetermined range, and the peak value of the loss tangent (tan δ) of the second adhesive layer was within a predetermined range. Therefore, the slipperiness of the first adhesive layer and the adhesion of the second adhesive layer during insertion were good, and the adhesion after foaming and curing was also good. On the other hand, in Comparative Example 1, the tack of the second adhesive layer was low, so the adhesion of the second adhesive layer during insertion was poor. Furthermore, in Comparative Examples 2 and 3, the tack of the first adhesive layer and the tack of the second adhesive layer were equal, and the tack of the first adhesive layer was high, so the slipperiness of the first adhesive layer during insertion was poor.

1... First adhesive layer 2... Second adhesive layer 3... Base material 4... First intermediate layer 5... Second intermediate layer 6... First separator 7... Second separator 10... Foamable adhesive sheet 11... After foaming and curing Adhesive sheet 20a... First member 20b... Second member 100... Article

Claims (6)

A foamable adhesive sheet comprising a first adhesive layer and a second adhesive layer disposed on one side of the first adhesive layer,
The first adhesive layer and the second adhesive layer contain a curable adhesive,
At least one of the first adhesive layer and the second adhesive layer further contains a foaming agent,
The tack of the first adhesive layer is 0 gf or more and less than 10 gf,
The tack of the second adhesive layer is 10 gf or more and 400 gf or less,
A foamable adhesive sheet, wherein the second adhesive layer has a peak value of loss tangent (tan δ) of 100°C or more and 180°C or less. The foamable adhesive sheet according to claim 1, wherein the first adhesive layer contains the foaming agent. The foamable adhesive sheet according to claim 1, wherein the first adhesive layer and the second adhesive layer contain the foaming agent. The foamable adhesive sheet according to any one of claims 1 to 3, comprising a base material between the first adhesive layer and the second adhesive layer. The arithmetic mean roughness (Ra) of the surface of the first adhesive layer opposite to the second adhesive layer is 0.3 μm or more and 1.5 μm or less,
The foamable adhesive sheet according to any one of claims 1 to 4, wherein the first adhesive layer has a static friction coefficient of 0.33 or less on a surface opposite to the second adhesive layer. an arrangement step of arranging the foamable adhesive sheet according to any one of claims 1 to 5 between the first member and the second member;
an adhesion step of foaming and curing the foamable adhesive sheet and adhering the first member and the second member;
A method for manufacturing an article, comprising:

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