JP2021123602A - Adhesive sheet - Google Patents

Abstract

To provide an adhesive sheet which can be easily peeled from an adherend by coming into contact with water.SOLUTION: An adhesive sheet 10 includes an adhesive layer (X)2 formed of an acrylic adhesive composition containing an acrylic polymer (A) having a carboxy group, a neutralizer (B) and a crosslinking agent (C), and recesses 1 are present on at least one surface of the adhesive layer (X)2. The adhesive sheet 10 is formed using the acrylic adhesive composition in which: the component (B) is an amine compound; and the component (A) contains 0.1-20 mass% of a constituent unit (a2) derived from a monomer (am2) containing a carboxy group in all the constituent units of the component (A).SELECTED DRAWING: Figure 1

Description

The present invention relates to an adhesive sheet. More specifically, the present invention relates to an adhesive sheet that exhibits self-removability upon contact with water.

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

For example, Patent Document 1 tentatively describes that the glass transition temperature of a homopolymer contains a (meth) acrylate and an alicyclic (meth) acrylate that satisfy specific ranges, respectively, and a photopolymerization initiator. Using the fixing adhesive composition and the temporary fixing adhesive composition, the member is temporarily fixed, the processed member is immersed in an organic solvent, and the cured product of the composition is removed. Temporary fixing methods are disclosed.
Further, for example, Patent Document 2 describes a step of forming a unit in which a brittle material is fixed to a hard plate via a double-sided adhesive sheet having an adhesive layer on both sides, and peeling the brittle material from the hard plate. In the processing method including, the unit is immersed in a liquid insoluble or sparingly soluble in the adhesive, and the liquid is applied to the interface between the double-sided adhesive sheet and a brittle material or the interface between the double-sided adhesive sheet and a hard plate. A method for processing a brittle material is disclosed, which comprises peeling the brittle material from an end portion of the unit after the intrusion.

Japanese Unexamined Patent Publication No. 2015-108044 Japanese Unexamined Patent Publication No. 2003-338475

By the way, in recent years, when an adhesive sheet as disclosed in Patent Documents 1 and 2 is used in the manufacturing process of various products, the adhesive sheet is immersed in a solvent or the like from the viewpoint of improving productivity, and then the adhesive sheet is used. There is a demand for shortening the time required to separate the solvent from the adherend.
Further, even in the pressure-sensitive adhesive sheet used in other than the production process as described above, it is required to shorten the peeling processing time from the viewpoint of improving workability at the time of peeling.
Further, in the method of immersing in the solvent or the like to peel off the adhesive sheet, it is desirable that the adhesive sheet can be treated with a safer solvent from the viewpoint of environmental consideration and workability.
From this point of view, it is an object of the present invention to provide an adhesive sheet that can be easily peeled off from an adherend when it comes into contact with water.

The present inventor has formed a pressure-sensitive adhesive layer with a specific acrylic pressure-sensitive adhesive composition and provided a recess on at least one surface of the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive sheet having the specific pressure-sensitive adhesive layer. The present invention has been completed by finding that the above problems can be solved.
That is, the present invention provides the following [1] to [11].
[1] It has a pressure-sensitive adhesive layer (X) formed of an acrylic pressure-sensitive adhesive composition containing an acrylic polymer (A) having a carboxy group, a neutralizing agent (B), and a cross-linking agent (C). An adhesive sheet having recesses on at least one surface of the adhesive layer (X).
[2] The pressure-sensitive adhesive sheet according to the above [1], wherein the component (B) is an amine compound.
[3] The structural unit (a2) derived from the monomer (am2) in which the component (A) contains a carboxy group is 0.1 to 20% by mass in 100% by mass of all the structural units constituting the component (A). The adhesive sheet according to the above [1] or [2], which contains%.
[4] The content of the component (A) in the acrylic pressure-sensitive adhesive composition is 75 to 95% by mass in the total amount (100% by mass of the active ingredient) of the acrylic pressure-sensitive adhesive composition. ] To [3]. The adhesive sheet according to any one of.
[5] The content of the component (B) in the acrylic pressure-sensitive adhesive composition is 0.05 to 10 parts by mass with respect to the total amount of the component (A) (100 parts by mass of the active ingredient). The adhesive sheet according to any one of 1] to [4].
[6] The pressure-sensitive adhesive sheet according to any one of [1] to [5] above, wherein the component (C) is at least one selected from an epoxy-based cross-linking agent and a metal chelate-based cross-linking agent.
[7] The content of the component (C) in the acrylic pressure-sensitive adhesive composition is 0.05 to 10 parts by mass with respect to the total amount of the component (A) (100 parts by mass of the active ingredient). The adhesive sheet according to any one of 1] to [6].
[8] The pressure-sensitive adhesive sheet according to any one of [1] to [7], wherein the height difference between the recesses is 0.5 μm or more.
[9] When the pressure-sensitive adhesive layer (X) is viewed in a plan view, the recesses that are continuously bonded from one part to the other part of the contour of the surface of the pressure-sensitive adhesive layer (X) are present. 8] The adhesive sheet according to any one of.
[10] The pressure-sensitive adhesive sheet according to any one of [1] to [9] above, wherein the pressure-sensitive adhesive strength of the surface of the pressure-sensitive adhesive layer (X) where the recesses are present is 0.20 to 10.00 N / 25 mm. ..
[11] The pressure-sensitive adhesive sheet according to any one of the above [1] to [10], which has a base material.

According to the present invention, it is possible to provide an adhesive sheet that can be easily peeled off from an adherend when it comes into contact with water.

It is a cross-sectional schematic diagram which shows an example of the structure of the pressure-sensitive adhesive sheet of this invention, and is the cross-sectional schematic view cut by the surface which can distinguish the recess existing in the surface of the pressure-sensitive adhesive layer (X). It is a cross-sectional schematic diagram which shows an example of the structure of the pressure-sensitive adhesive sheet of this invention, and is the cross-sectional schematic view cut by the surface which can distinguish the recess existing in the surface of the pressure-sensitive adhesive layer (X). It is a cross-sectional schematic diagram which shows an example of the structure of the pressure-sensitive adhesive sheet of this invention, and is the cross-sectional schematic view cut by the surface which can distinguish the recess existing in the surface of the pressure-sensitive adhesive layer (X). It is a cross-sectional schematic diagram which shows an example of the structure of the pressure-sensitive adhesive sheet of this invention, and is the cross-sectional schematic view cut by the surface which can distinguish the recess existing in the surface of the pressure-sensitive adhesive layer (X). It is a cross-sectional schematic diagram of the water contact peelability evaluation sample of the pressure-sensitive adhesive sheet in an Example, and is the cross-sectional schematic view cut by the surface which can discriminate the concave part existing on the surface of the pressure-sensitive adhesive layer (X). It is a plane schematic diagram which shows an example of the pressure-sensitive adhesive sheet of this invention. It is a plane schematic diagram which shows an example of the pressure-sensitive adhesive sheet of this invention. It is sectional drawing which shows an example of the structure of the release material which the adhesive sheet of this invention may have, and is the sectional schematic diagram of the release material cut by the surface which can distinguish the convex part existing on the surface of the release material. Is. This is an example of a scanning electron microscope (SEM) image when the height difference and width of the recesses of the pressure-sensitive adhesive sheet produced in Example 1 which is an example of this embodiment are confirmed. This is an example of a scanning electron microscope (SEM) image when the height difference and width of the convex portion of the release material 1 used when producing the pressure-sensitive adhesive sheet produced in Example 1 which is an example of this embodiment is confirmed. .. This is an example of a scanning electron microscope (SEM) digital microscope image when the pattern shape of the concave portion of the pressure-sensitive adhesive sheet produced in Example 1 which is an example of this embodiment is confirmed. This is an example of a scanning electron microscope (SEM) image when the pattern shape of the convex portion of the release material 1 used when producing the pressure-sensitive adhesive sheet produced in Example 1 which is an example of this embodiment is confirmed.

[Adhesive sheet]
The pressure-sensitive adhesive sheet of the present invention has a pressure-sensitive adhesive layer (X) formed of an acrylic pressure-sensitive adhesive composition containing an acrylic polymer (A) having a carboxy group, a neutralizing agent (B), and a cross-linking agent (C). There is a recess on at least one surface of the pressure-sensitive adhesive layer (X).

Hereinafter, an example of the pressure-sensitive adhesive sheet according to the embodiment of the present invention will be described with reference to each figure, but the pressure-sensitive adhesive sheet of the present invention is not limited to the following examples as long as the effects of the present invention are exhibited. No.
1 to 4 are schematic cross-sectional views of the pressure-sensitive adhesive sheets 10, 20, 30 and 40, respectively, showing an example of the structure of the pressure-sensitive adhesive sheet of the present invention, in which the recess 1 is present on at least one surface. FIG. 5 is a schematic cross-sectional view of the pressure-sensitive adhesive layer (X) (hereinafter, also simply referred to as “layer (X)”) 2 cut along a surface so that the recess 1 can be identified.
For example, when the pressure-sensitive adhesive sheet 70, which is an example of the structure of the pressure-sensitive adhesive sheet of the present invention shown in the schematic plan view of FIG. 7, is cut along the line AA, a schematic cross-sectional view as shown in FIGS. can get.

As one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 10 shown in FIG. 1, a pressure-sensitive adhesive sheet composed of a single layer of layer (X) 2 can be mentioned. In the case of the adhesive sheet shown in FIG. 1, an adherend to be peeled off when the layer (X) 2 is brought into contact with water can be attached to the surface where the recess 1 is present. Further, in the adhesive sheet 10 shown in FIG. 1, the adhesive sheet may have recesses 1 on both surfaces of the layer (X) 2 (not shown), and the exposed surface on one side of the layer (X) 2 and both of them. A release material may be provided on the exposed surface (not shown).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, a pressure-sensitive adhesive sheet 20 shown in FIG. 2 has a structure in which a base material 3 and a layer (X) 2 are laminated in this order. .. By providing the layer (X) 2 on the base material 3, the shape stability of the adhesive sheet can be improved and the adhesive sheet can be given elasticity, so that the release material is removed from the layer (X) 2. It is preferable from the viewpoint of improving workability when peeling the adhesive sheet from the adherend or the adherend.
In the adhesive sheet 20 shown in FIG. 2, the adhesive sheet may have a recess 1 on the surface side in contact with the base material 3 of the layer (X) 2 (not shown), and the base material 3 side of the layer (X) 2 and An adhesive sheet having recesses 1 on both surfaces on the opposite side of the base material 3 may be used (not shown), and the surface of the layer (X) 2 on the side opposite to the base material 3 and / or the base material 3 A release material may be provided on the surface opposite to the layer (X) 2 (not shown).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 30 shown in FIG. 3, a double-sided pressure-sensitive adhesive sheet having a multilayer structure in which a layer (X) 2 is laminated on both sides of a base material 3 can be mentioned. Be done. In the pressure-sensitive adhesive sheet 30 shown in FIG. 3, the two layers (X) 2 may be the same layer (X) 2 or different layers (X) 2. Further, the adhesive sheet 30 shown in FIG. 3 may also be an adhesive sheet having a recess 1 on the surface side in contact with the base material 3 of the layer (X) 2 (not shown), and the base material of the layer (X) 2. An adhesive sheet having recesses 1 on both the surface of the 3 side and the side opposite to the base material 3 may be used (not shown).
Further, in the pressure-sensitive adhesive sheet 30 shown in FIG. 3, one of the two layers (X) 2 may be used as another pressure-sensitive adhesive layer other than the layer (X) 2 having no recess 1 on the surface (not shown). ).

Further, as one aspect of the pressure-sensitive adhesive sheet of the present invention, for example, as in the pressure-sensitive adhesive sheet 40 shown in FIG. 4, in the pressure-sensitive adhesive sheet 30 shown in FIG. 3, the surface of the layer (X) 2 on the opposite side to the base material 3 A release material 4-1 and a release material 4-2 may be provided on the upper surface (exposed surface).
In FIG. 4, the release material 4-1 is a release material having a convex portion 4a paired with the concave portion 1 of the layer (X) 2, and the release material 4-2 is a release material having no convex portion. In the pressure-sensitive adhesive sheet 40 shown in FIG. 4, both the release material 4-1 may be used as the release material, or both may use the release material 4-2. However, from the viewpoint of facilitating the shape of the recess 1 on the layer (X) 2 during storage and / or transportation of the pressure-sensitive adhesive sheet 40, and the method for manufacturing the pressure-sensitive adhesive sheet, which is one aspect of the present invention described later. As described, from the viewpoint of facilitating the formation of the concave portion 1, the release material 4- having the convex portion 4a paired with the concave portion 1 of the layer (X) 2 on the surface having the concave portion 1 of the layer (X) 2. It is preferable to provide 1. The same applies to the case where the release material is provided in the adhesive sheets 10, 20 and 30 shown in FIGS. 1 to 3.

Further, FIG. 5 shows a schematic cross-sectional view of the water contact peelability evaluation sample 100 of the pressure-sensitive adhesive sheet in the examples of the present application. The pressure-sensitive adhesive sheet 50 shown in FIG. 5 includes a pressure-sensitive adhesive layer (X) 2, a base material 3, and a pressure-sensitive adhesive layer (Z) which is a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer (X) (hereinafter, simply "layer (Z)". ) ”) 5 is a double-sided adhesive sheet having a multi-layer structure laminated in this order.
In the adhesive sheet 50 shown in FIG. 5, the recess 1 of the layer (X) 2 does not come into contact with the adherend 101 even when it comes into contact with the adherend (glass plate) 101, and is along the inside of the recess 1. Since water infiltrates, for example, the time for water to enter the interface between the layer (X) 2 and the adherend 101 and the layer (X) 2 are due to the water as compared with the layer (Z) having no recess 1. It is thought that the swelling time can be shortened.

Further, in the adhesive sheet 20 shown in FIG. 2, the base material 3 and the layer (X) 2 may be directly laminated as shown in FIG. 2, and between the base material 3 and the layer (X) 2. In addition, it may be laminated via another layer. Here, "direct lamination" means, for example, in the case of the adhesive sheet 20 shown in FIG. 2, two layers are directly formed without having another layer between the base material 3 and the layer (X) 2. Refers to the contacting configuration.
Further, in the adhesive sheets 30 and 40 shown in FIGS. 3 and 4, the base material 3 and the layer (X) 2 may be directly laminated with three layers as shown in each figure, and may be directly laminated with the base material 3. It may be laminated between one of the layers (X) 2 or between the base material 3 and both layers (X) 2 via the other layer.
Further, in the pressure-sensitive adhesive sheet 50 shown in FIG. 5, the layer (X) 2, the base material 3, and the layer (Z) 5 may be directly laminated as shown in FIG. 5, and the layer (X) may be directly laminated. ) 2 and the base material 3 and / or between the base material 3 and the layer (Z) 5 may be laminated via another layer.
Further, for example, as shown in FIGS. 1 to 5, the portion where the concave portion 1 does not exist is relatively the convex portion 2a of the layer (X) 2 with respect to the concave portion 1 of the layer (X) 2. Sometimes referred to.

The pressure-sensitive adhesive sheet according to one aspect of the present invention is a pressure-sensitive adhesive sheet that exhibits self-peeling property upon contact with water. Then, in the pressure-sensitive adhesive sheet according to one aspect of the present invention, the surface of the pressure-sensitive adhesive sheet (X) having a recess is attached to the adherend, and then the pressure-sensitive adhesive layer (X) is brought into contact with water. It is preferable that the pressure-sensitive adhesive sheet can be self-peeled from the adherend.
In the present specification, "self-peeling" means that the adhesive sheet is peeled off or peeled off from the adherend without applying a force for peeling off the adhesive sheet, and the adhesive sheet is peeled off. Such a property is referred to as "self-peeling property".
Further, in the present specification, the self-peeling that the adhesive sheet develops due to contact with water is referred to as "water contact peeling", and such a property is referred to as "water contact peeling property".
Here, the "water" also includes an aspect of an "aqueous solution" in which a liquid or solid other than water is dissolved, as long as the effects of the present application are exhibited. The "water" can be appropriately selected depending on the use of the adhesive sheet, but tap water; pure water such as ion-exchanged water, RO water, distilled water; and ultrapure water; and the like can be preferably used. It is possible to more preferably use one or more selected from the group consisting of pure water and ultrapure water.

When the layer (X) used in the present invention comes into contact with water, the effect of water infiltrating the interface between the layer (X) and the adherend due to the hydrophilicity of the layer (X) and the layer (X) itself. Self-peeling occurs due to the combined action of the effect of water infiltrating the interface between the layer (X) and the adherend due to the effect of taking in water and swelling (hereinafter, also referred to as "water swelling property"). It is thought that it will occur.
Since the layer (X) used in the present invention has the recesses, water penetrates along the recesses, and when the pressure-sensitive adhesive sheet is viewed in a plan view, not only from the outer edge portion of the pressure-sensitive adhesive sheet but also from the outer edge portion of the pressure-sensitive adhesive sheet. Water can easily enter the interface between the layer (X) and the adherend from the location where the recess exists. In addition, the time for the layer (X) to swell with water due to the intrusion of water from the recess is also shortened. As a result, it is considered that the time for water to infiltrate the interface between the layer (X) and the adherend is significantly shortened to the extent that the adhesive sheet can be self-peeled from the adherend, and the water contact peelability is remarkably improved. Be done.
From this point of view, as a method of bringing the layer (X) into contact with water, the layer (X) is immersed in water so that the interface between the layer (X) and the adherend is located below the water surface. It is more preferable to immerse the layer (X) in water so that at least the recesses located on the outer periphery of the layer (X) are immersed in water when the layer (X) is viewed in a plan view. It is more preferable to immerse the layer (X) in water so that the entire layer (X) is immersed in water.

The temperature of the water is not particularly limited as long as the effect of the present invention is not impaired, but is preferably more than 0 ° C. and lower than 100 ° C., more preferably 4 ° C. or higher and lower than 50 ° C., and further preferably 5 ° C. or higher and 40 ° C. It is as follows. The pressure-sensitive adhesive sheet, which is one aspect of the present invention, can obtain a sufficient effect even when treated with water at room temperature (25 ° C.). That is, since water contact peelability can be exhibited even when the water that comes into contact with the pressure-sensitive adhesive sheet is not subjected to treatment such as heating or cooling, workability and economy when using the pressure-sensitive adhesive sheet (during peeling treatment) are achieved. Also excellent.

In addition, the pressure-sensitive adhesive sheet, which is one aspect of the present invention, is self-peeled from the adherend when the pressure-sensitive adhesive sheet is immersed in water in the water contact peelability evaluation evaluated by the method described in Examples described later. The time required is preferably 10 minutes or less, more preferably 5 minutes or less, still more preferably 1 minute or less, still more preferably less than 1 minute.

Further, in the present specification, with respect to a preferable numerical range (for example, a range such as content), the lower limit value and the upper limit value described stepwise can be combined independently. For example, from the description "preferably 10 or more, more preferably 30 or more, and preferably 90 or less, more preferably 60 or less", "preferable lower limit value (10)" and "more preferable upper limit value (60)". Can be combined to set a suitable range of "10 or more and 60 or less". Similarly, from the description of "preferably 10 to 90, more preferably 30 to 60", it can be changed to "10 to 60". Unless otherwise specified, when simply describing "10 to 90" as a preferable numerical range, it represents a range of 10 or more and 90 or less.
Further, in the present specification, for example, "(meth) acrylic acid" means both "acrylic acid" and "methacrylic acid", and other similar terms are also used.
Further, in the present specification, the "active ingredient" in the pressure-sensitive adhesive composition refers to the normal temperature (25) excluding the solvent (water or organic solvent) that is not directly involved in the reaction among the components contained in the pressure-sensitive adhesive composition. Refers to a liquid component at (° C.) and a solid component at room temperature (25 ° C.).
Hereinafter, the pressure-sensitive adhesive sheet of the present invention will be described in more detail, but the aspects of the present invention are not limited thereto.

<Adhesive layer (X)>
The pressure-sensitive adhesive layer (X) is also referred to as an acrylic polymer (A) having a carboxy group (hereinafter, also referred to as “component (A)”) and a neutralizing agent (B) (hereinafter, also referred to as “component (B)”). A layer formed by an acrylic pressure-sensitive adhesive composition (hereinafter, also simply referred to as “stickiness composition”) containing a cross-linking agent (C) (hereinafter, also referred to as “component (C)”). And there is a recess on at least one surface.
Hereinafter, each component contained in the pressure-sensitive adhesive composition will be described.

(Component (A): Acrylic polymer (A) having a carboxy group)
When the pressure-sensitive adhesive composition does not contain the acrylic polymer (A) having a carboxy group, the water contact peelability of the obtained pressure-sensitive adhesive sheet is inferior. It is considered that this is because the hydrophilicity and water swelling property of the layer (X) cannot be sufficiently obtained, and the invasion of water into the interface between the layer (X) and the adherend does not proceed sufficiently.

The component (A) is a structural unit (a1) derived from an alkyl (meth) acrylate (am1) (hereinafter, also referred to as “monomer (am1)”) (hereinafter, also referred to as “constituent unit (a1)”). ).
The number of carbon atoms of the alkyl group contained in the monomer (am1) is preferably 1 to 24, more preferably 1 to 12, still more preferably 2 to 10, and even more preferably 4 to 24 from the viewpoint of improving the adhesive properties. It is 8.
The alkyl group contained in the monomer (am1) may be a straight chain alkyl group or a branched chain alkyl group.

Examples of the monomer (am1) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth). ) Acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate and the like.
As the monomer (am1), one or more selected from the group consisting of ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isooctyl (meth) acrylate is preferable, and n One or more selected from the group consisting of -butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate is more preferable, and n-butyl (meth) acrylate is further preferable.
These monomers (am1) may be used alone or in combination of two or more.

The content of the structural unit (a1) is preferably 45 to 99% by mass, more preferably 55 to 98% by mass, still more preferably 65 to 96% by mass, based on 100% by mass of all the structural units constituting the component (A). , More preferably 75 to 94% by mass, and even more preferably 80 to 90% by mass.
The content of the structural unit (a1) can also be calculated as the content of the monomer (am1) in 100% by mass of all the monomers used when polymerizing the component (A).

The component (A) is preferably a structural unit (a2) derived from a monomer (am2) containing a carboxy group (hereinafter, also referred to as “monomer (am2)”) (hereinafter, “constituent”). It is an acrylic polymer having a unit (a2).

Examples of the monomer (am2) include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, and citraconic acid, and the like. Anhydrous; 2- (acryloyloxy) ethyl succinate, 2-carboxyethyl (meth) acrylate and the like can be mentioned.
Further, the monomer (am2) also includes an anhydride of the ethylenically unsaturated dicarboxylic acid and a derivative of the ethylenically unsaturated dicarboxylic acid. This is because it is possible to generate a carboxy group by hydrolyzing a group derived from the unsaturated carboxylic acid anhydride in the component (A). Examples of the unsaturated carboxylic acid anhydride include the anhydrides of the above-mentioned unsaturated polyvalent carboxylic acids such as maleic anhydride, citraconic anhydride, and nadicic anhydride.
As the monomer (am2), one or more selected from ethylenically unsaturated monocarboxylic acid and ethylenically unsaturated dicarboxylic acid is preferable, ethylenically unsaturated monocarboxylic acid is more preferable, and it is composed of (meth) acrylic acid. One or more selected from the group is more preferable, and acrylic acid is even more preferable.
These monomers (am2) may be used alone or in combination of two or more.

The component (A) more preferably contains the structural unit (a2) in an amount of 0.1 to 20% by mass based on 100% by mass of all the monomers constituting the component (A).
It is preferable that the structural unit (a2) is contained in an amount of 0.1% by mass or more based on 100% by mass of all the structural units constituting the component (A) because the water contact peelability of the obtained pressure-sensitive adhesive sheet is improved. Then, by containing 20% by mass or less of the structural unit (a2) in 100% by mass of all the structural units constituting the component (A), it is preferable from the viewpoint that the glass transition temperature can be set low and the adhesive strength can be improved. From such a viewpoint, the content of the structural unit (a2) is more preferably 0.5% by mass or more, still more preferably 1% by mass or more, out of 100% by mass of all the structural units constituting the component (A). , More preferably 15% by mass or less, still more preferably 10% by mass or less, still more preferably 5% by mass or less.
The content of the structural unit (a2) can also be calculated as the content of the monomer (am2) in 100% by mass of all the monomers used when polymerizing the component (A).

The component (A) is preferably a structural unit (a3) derived from a hydroxy group-containing monomer (am3) (hereinafter, also referred to as “monomer (am3)”) (hereinafter, “constituent”). It is an acrylic polymer having a unit (a3).

Examples of the monomer (am3) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxy. Hydroxyalkyl (meth) acrylates such as butyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol can be mentioned.
As the monomer (am3), hydroxyalkyl (meth) acrylate is preferable, and one or more selected from the group consisting of 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate is more preferable, and 2- Hydroxyethyl (meth) acrylate is more preferred.
These monomers (am3) may be used alone or in combination of two or more.

The component (A) more preferably contains the structural unit (a3) in an amount of 1 to 30% by mass based on 100% by mass of all the monomers constituting the component (A).
It is preferable that the structural unit (a3) is contained in an amount of 1% by mass or more based on 100% by mass of all the structural units constituting the component (A) because the water contact peelability of the obtained pressure-sensitive adhesive sheet is improved. It is preferable that the structural unit (a3) is contained in an amount of 30% by mass or less based on 100% by mass of all the structural units constituting the component (A) from the viewpoint that the glass transition temperature can be set low and the adhesive strength can be improved. From such a viewpoint, the content of the structural unit (a3) is more preferably 3% by mass or more, still more preferably 6% by mass or more, still more preferably more preferably, out of 100% by mass of all the structural units constituting the component (A). Is 9% by mass or more, and more preferably 25% by mass or less, still more preferably 20% by mass or less, still more preferably 15% by mass or less.
The content of the structural unit (a3) can also be calculated as the content of the monomer (am3) in 100% by mass of all the monomers used when polymerizing the component (A).

In the component (A), the total content of the constituent units (a1), (a2) and (a3) is preferably 80 to 100% by mass, based on 100% by mass of all the constituent units constituting the component (A). It is preferably 85 to 100% by mass, more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass, and even more preferably 98 to 100% by mass.
The total content of the structural units (a1), (a2) and (a3) is the monomer (am1), (am2) in 100% by mass of all the monomers used when polymerizing the component (A). And (am3) can also be calculated as the total content.

The component (A) is a structural unit (a4) derived from other monomers (am4) (hereinafter, also referred to as “monomer (am4)”) other than the monomers (am1) to (am3). (Hereinafter, it may also be referred to as "constituent unit (a4)").

Examples of the monomer (am4) include simple amino group-containing monomers, substituted amino group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, and alkoxysilyl group-containing monomers. Functional group-containing monomers other than the metric (am2) and (am3); olefins such as ethylene, propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; diene monomers such as butadiene, isoprene and chloroprene Metrics: Cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, imide (Meta) acrylate having a cyclic structure such as (meth) acrylate; styrene, α-methylstyrene, vinyl toluene, vinyl formate, vinyl acetate, acrylonitrile, (meth) acrylamide, (meth) acrylonitrile, (meth) acryloylmorpholine, N. − Examples include vinylpyrrolidone. When these monomers (am4) are used, they may be used alone or in combination of two or more.

Examples of the amino group- or substituted amino group-containing monomer include 2-aminoethyl (meth) acrylate, 2-aminoethyl (meth) acrylamide, N-methylaminoethyl (meth) acrylate, and N-methylaminoethyl (meth) acrylate. ) Acrylamide and the like.

Examples of the epoxy group-containing monomer include an epoxy group-containing (meth) acrylic acid ester and a non-acrylic epoxy group-containing monomer. Examples of the epoxy group-containing (meth) acrylic acid ester include glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, (3,4-epoxycyclohexyl) methyl (meth) acrylate, and 3-epoxycyclo-2-. Examples thereof include hydroxypropyl (meth) acrylate. Examples of the non-acrylic epoxy group-containing monomer include glycidyl crotonate and allyl glycidyl ether.

Further, as a method for introducing a carboxy group into the component (A) other than the method using the monomer (am2), a copolymer of the monomer (am1) or a simple polymer other than the monomer (am1) is used. It is also possible to use a method in which the copolymer with the monomer is polymerized, and then the homopolymer or the copolymer is partially saponified to introduce a carboxy group into the component (A). In this case, it is preferable to adjust the content of the structural unit (a1) remaining in the component (A) without being saponified to be the content of the above-mentioned structural unit (a1), and the suitable content thereof. Is the same.

The component (A) can be produced by using a known polymerization method such as bulk polymerization, solution polymerization, or emulsion polymerization.
When these components (A) are copolymers having two or more kinds of structural units, the form of the copolymer is any of a block copolymer, a random copolymer, and a graft copolymer. It may be.

The mass average molecular weight (Mw) of the component (A) is not particularly limited as long as the effects of the present invention are exhibited, but the obtained adhesive sheet has sufficient adhesiveness before water contact and better water. From the viewpoint of facilitating the development of contact peelability, the amount is preferably 100,000 to 3 million, more preferably 200,000 to 2 million, and even more preferably 300,000 to 1,000,000.
The value of the mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, and specifically, a value measured based on the method described in Examples. be.

The content of the component (A) in the pressure-sensitive adhesive composition is such that the pressure-sensitive adhesive makes it easier for the obtained pressure-sensitive adhesive sheet to exhibit sufficient stickiness before water contact and better water-contact peelability. It is preferably 75 to 95% by mass, more preferably 80 to 92% by mass, and further preferably 85 to 90% by mass in the total amount of the composition (100% by mass of the active ingredient).
The content of the component (A) can also be calculated as the blending amount of the component (A) in 100% by mass of all the components to be blended when preparing the pressure-sensitive adhesive composition. Hereinafter, the same applies to the contents of the component (B), the component (C) and other components contained in the pressure-sensitive adhesive composition.

(Component (B): Neutralizer)
When the pressure-sensitive adhesive composition does not contain the neutralizing agent (B), the water swelling property of the layer (X) cannot be sufficiently obtained, and the water contact peelability of the obtained pressure-sensitive adhesive sheet is inferior.
The neutralizing agent (B) reacts with a part or all of the carboxy groups of the component (A), and the reaction site is partially salt-like (hereinafter, also referred to as “salt-like site”). Is thought to form. Then, the layer (X) is formed by a salty moiety formed by the carboxy group of the component (A) and the component (B) and a crosslinked structure formed by the component (A) and the cross-linking agent (C) described later. It is considered that the hydrophilicity and water swelling property of the layer (X) are improved, and the layer (X) exhibits excellent water contact peelability.

As the component (B), various basic compounds can be used as long as the effects of the present invention are exhibited, and an amine compound is preferable.
Examples of the amine compound include ammonia, alkaline ammonium salts and primary amine compounds such as monoethylamine and monoethanolamine; secondary amine compounds such as diethylamine and diethanolamine; triethylamine, triethanolamine, N and N. -Dimethylformamide Diethylacetal, N, N, N-trimethylethylenediamine, N-methyldiethanolamine, N, N-diethylhydroxylamine, N, N-diethylethanolamine and other tertiary amine compounds; Diamine, polyethyleneimine and the like 1 Examples thereof include amino compounds having a plurality of nitrogen atoms in the molecule, cyclic amino compounds such as pyridine; and organic amino compounds exhibiting alkalinity. The amine compound is preferably a tertiary amine compound.

Further, as described above, it is considered that the component (B) can impart better hydrophilicity when forming a salty moiety with the carboxy group in the component (A), and therefore, among the amine compounds. , Hydroxy group-containing amine compounds are more preferred. When the component (B) is a hydroxy group-containing amine compound, it is considered that the hydroxy group derived from the component (B) makes it easier for the layer (X) to take in water and further improves the water swelling property of the layer (X). Be done. From this point of view, the component (B) is more preferably a hydroxy group-containing tertiary amine compound, and even more preferably triethanolamine.
These neutralizers (B) may be used alone or in combination of two or more.

The content of the component (B) in the pressure-sensitive adhesive composition is set to the total amount of the component (A) (100 parts by mass of the active ingredient) from the viewpoint of facilitating the obtained pressure-sensitive adhesive sheet to exhibit good water contact peelability. On the other hand, it is preferably 0.05 to 10 parts by mass, more preferably 0.1 to 9 parts by mass, still more preferably 1 to 8 parts by mass, still more preferably 4 to 8 parts by mass, and even more preferably 6 parts. ~ 8 parts by mass.

(Component (C): Crosslinking agent)
When the pressure-sensitive adhesive composition does not contain the cross-linking agent (C), the water swellability of the layer (X) cannot be sufficiently obtained.
The component (C) is a compound that reacts with the component (A) to form a crosslinked structure, and is a compound that reacts with a part or all of the carboxy groups of the component (A) to crosslink the component (A). It is preferable to have.
As described above, the pressure-sensitive adhesive layer (X) is a layer having a crosslinked structure derived from the component (A) and the component (C) and a salt-like moiety derived from the component (A) and the component (B). It is considered that the excellent water contact peelability of the layer (X) is exhibited.

Examples of the component (C) include an epoxy-based cross-linking agent, a methylol-based cross-linking agent, a metal chelate-based cross-linking agent, an aziridine-based cross-linking agent, and the like. Among these, one or more selected from an epoxy-based cross-linking agent and a metal chelate-based cross-linking agent is preferable, and an epoxy-based cross-linking agent is more preferable.

Examples of the epoxy-based cross-linking agent include neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, phthalic acid diglycidyl ester, and dimer acid dimerate. Diglycidyl ether, diglycerol triglycidyl ether, sorbitol tetraglycidyl ether, 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-m-xylylene diamine, Examples thereof include N, N, N', N'-tetraglycidyl diaminodiphenyl methane, 1,6-hexanediol diglycidyl ether, trimethylolpropan diglycidyl ether, diglycidyl aniline, and diglycidyl amine. These may be used alone or in combination of two or more.

Examples of the metal chelate-based cross-linking agent include polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium, as well as acetylacetone, ethyl acetoacetate, and tris (tris). Examples thereof include metal chelate compounds in which 2,4-pentandionate) and the like are coordinated. These may be used alone or in combination of two or more.
These cross-linking agents (C) may be used alone or in combination of two or more.

The content of the component (C) in the pressure-sensitive adhesive composition is such that the obtained pressure-sensitive adhesive sheet easily develops sufficient tackiness before water contact and better water contact peelability. With respect to the total amount of A) (100 parts by mass of the active ingredient), preferably 0.05 to 10 parts by mass, more preferably 0.1 to 9 parts by mass, still more preferably 1 to 8 parts by mass, still more preferably 4 It is ~ 8 parts by mass, more preferably 6 to 8 parts by mass.

(Other additives)
The pressure-sensitive adhesive composition may contain other additives in addition to the above-mentioned components (A) to (C) as long as the effects of the present invention are not impaired.
Examples of other additives include resin components other than component (A), surfactants, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, conductive agents, antistatic agents, slip agents, and antiblocking agents. , Colorants, plasticizers and the like.
When these additives are contained, the content of each is preferably 0.01 to 20% by mass, more preferably 0.01 to 10% by mass, and further preferably 0.% by mass in 100% by mass of the pressure-sensitive adhesive composition. It is 01 to 5% by mass, more preferably 0.01 to 2% by mass.
Examples of the resin component other than the component (A) include polyolefin-based resins such as polyethylene and polypropylene; polyester-based resins; and the like.

(Recess)
The "recess" included in the layer (X) refers to a recess intentionally provided so as not to come into contact with the adherend when the surface having the recess of the layer (X) is attached to the adherend. ..
The shape of the concave portion when the layer (X) is viewed in a plan view can be appropriately selected depending on the use of the pressure-sensitive adhesive sheet, and may be a fixed shape or an irregular shape.
When the shape of the concave portion when the layer (X) is viewed in a plan view is a fixed shape, for example, a polygon such as a triangle, a quadrangle (including a rectangle, a square, and a trapezoid), a pentagon, and a hexagon; Partly or wholly rounded (also referred to as "rounded corners (R)") shape; circular such as a perfect circle or ellipse; semicircular such as semicircle, semi-elliptical, U-shaped; etc. A shape represented by a closed area surrounded by at least three lines (including straight lines and curves) and one or more shapes selected from a combination of these shapes (hereinafter, also referred to as "independent concave shape"). Can be mentioned.

Further, as the shape of the concave portion when the layer (X) is viewed in a plan view, it is preferable to form a concave portion in contact with the contour of the surface having the concave portion of the layer (X), and the surface having the concave portion of the layer (X). A recess (hereinafter, "continuous recess shape") that is continuously connected from any one part of the contour of the It is more preferable to form a recess (also referred to as)), and a recess is formed which is continuously connected from any one part of the contour of the surface having the recess of the layer (X) to the other part of the contour. It is even more preferable to form a recess that is continuously connected from any one side of the surface having the recess of the layer (X) to the other side.
Since the concave portion has a continuous concave shape, water can easily infiltrate from the outer edge portion (contour portion) of the layer (X) toward the central portion when the layer (X) is viewed in a plan view, and as a result. , It is preferable because the water contact peelability of the adhesive sheet is further improved.

Therefore, for example, when the layer (X) is viewed in a plane, the shortest straight line connecting the center of gravity of the figure drawn by the contour of the surface having the recess of the layer (X) and an arbitrary point on the contour (hereinafter, "center of gravity"). It is preferable that at least a part of the continuous recess is present on the line segment (including the center of gravity) on the center of gravity side when the shortest distance to the center of gravity is divided into two equal parts. It is more preferable that at least a part of the continuous recess is present on the line segment (including the center of gravity) closest to the center of gravity in the case of dividing into three equal parts, and the shortest distance to the center of gravity is divided into five equal parts. It is more preferable that at least a part of the continuous recess is present on the line segment (including the center of gravity) closest to the center of gravity.
Further, when the layer (X) is viewed in a plan view, the longest straight line connecting the center of gravity of the figure drawn by the contour of the surface having the recess of the layer (X) and an arbitrary point on the contour (hereinafter, "up to the center of gravity"). It is preferable that at least a part of the continuous recess exists on the line segment (including the center of gravity) on the center of gravity side when the "longest distance" is divided into two equal parts, and the longest distance to the center of gravity is 3 mag. It is more preferable that at least a part of the continuous recesses is present on the line segment (including the center of gravity) closest to the center of gravity in the case of division, and the longest distance to the center of gravity is most divided into five equal parts. It is more preferable that at least a part of the continuous recesses is present on the line segment (including the center of gravity) near the center of gravity.

Further, the layer (X) has a continuous recess in which at least a part is present at a preferable position on the shortest distance to the center of gravity and a continuous recess in which at least a part is present in a preferable position on the longest distance to the center of gravity. It is even more preferable to have both. In this case, the preferable position where a part of the continuous recesses exist on the shortest distance to the center of gravity and the preferable position where a part of the continuous recesses exist on the longest distance to the center of gravity are independent of each other. Can be combined with. For example, when the shortest distance to the center of gravity is divided into two equal parts, a continuous recess in which at least a part of the recess exists on the line segment (including the center of gravity) closest to the center of gravity, and the longest distance to the center of gravity are 5 In the case of equal division, there may be a mode in which there is a continuous recess in which at least a part of the recess is present on the line segment (including the center of gravity) closest to the center of gravity side. And, among them, in the aspect of each concave part mentioned above, the aspect which combined the aspect which is more preferable degree is further preferable. That is, it is more preferable that at least a part of the continuous recesses is a combination of modes that exist closer to the center of gravity.

Examples of the continuous concave shape include a linear shape such as a straight line, a curved line, a zigzag, and a wavy line connecting any one place or a plurality of other places on the surface having the recess of the layer (X). .. Among these, a shape composed of straight lines is preferable, and examples of the shape include striped and lattice-shaped recesses described later. On the layer (X), at least one selected from these continuous concave shapes is arranged so as not to intersect at a predetermined interval, or is arranged so as to intersect with each other, for example, FIG. Recesses may be provided as a stripe shape shown in FIG. 7, a grid shape shown in FIG. 7, or another geometric pattern. In this case, a region 6 surrounded by the recesses 1 may be formed as in the grid pattern shown in FIG. 7, and the shape of the region 6 is the same as each shape described in the above-mentioned independent recess shape. The shape can be mentioned. The region 6 is also the convex portion 2a.
On the surface of the layer (X), a part of the continuous concave shape may be missing and a discontinuous shape may exist, or a continuous concave shape and an independent concave shape may be mixed. ..
Each shape that can be taken as a recess when the layer (X) is viewed in a plan view may be regularly present or irregularly present, but is patterned as shown in FIG. 6 or 7. It preferably exists regularly.
In the case of a grid shape as shown in FIG. 7, the same concave shape (straight line) intersects with each other to form one concave portion, and since there is no discontinuous portion, it is regarded as a single concave shape. be able to.

Further, the cross-sectional shape of the recess when the layer (X) is cut in the thickness direction may change depending on the cut surface and cannot be unconditionally specified. For example, a triangle or a quadrangle (rectangle, square, Polygons such as trapezoids, pentagons, hexagons, etc .; with a slight rounding of some or all of the corners of the polygon (also referred to as "rounded corners (R)"); half Semi-circular, semi-elliptical, U-shaped, etc.; etc.

The height difference of the recess is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 0.5 μm or more, more preferably 1.0 μm or more, still more preferably 3.0 μm or more, and It is preferably 50.0 μm or less, more preferably 30.0 μm or less, still more preferably 25.0 μm or less, still more preferably 20.0 μm or less.
The width of the recess is preferably 150 μm or less, more preferably 100 μm or less, still more preferably 75.0 μm or less, still more preferably 50.0 μm or less, still more preferably 35.0 μm or less. The lower limit of the width of the recess is not particularly limited, but is preferably 1.0 μm, more preferably 3.0 μm, and even more preferably 5.0 μm.
The height difference and the width of the recess are values measured by using the methods described in the examples, respectively.
Regarding the values described as the preferred range, for example, when the height difference of the recess is 0.5 μm or more, there is a portion having a height difference of 0.5 μm or more in any part of the recess. It is not necessary to have a height difference of 0.5 μm or more over the entire region of the recess. Similarly, even when a plurality of recesses having different shapes are present on the layer (X), it is sufficient that any of the recesses has a height difference of 0.5 μm or more, and all the recesses are 0.5 μm. It is not necessary to have the above height difference.
The height difference and width of the recess are values measured using the method described in the examples. For example, the distance 1h shown in FIG. 1 corresponds to the height difference of the recess. Further, the distance 1w shown in FIGS. 1, 6 and 7 corresponds to the width of the recess. As an example, if the cross-sectional image of the recess shown in FIG. 9, which is an image of a scanning electron microscope (SEM) taken by the method described in the example, is used for explanation, the distance 1h in FIG. 9 will be described. Corresponds to the height difference of the recess, and the distance 1w corresponds to the width of the recess.

Further, the shape of the concave portion is, for example, as will be described later, by applying the pressure-sensitive adhesive composition on a release material having a convex portion paired with the concave portion and drying the convex portion on the surface of the release material. The part shape can be formed by transferring it to the surface of the layer (X).

When a plurality of recesses are present on the layer (X), the shapes of the plurality of recesses may be the same or different from each other. In that case, the height difference and the width of the recesses are the same independently. May also be different.

The distance between the edges of the recess is preferably 50.0 μm or more, more preferably 100 μm or more, still more preferably 150 μm or more, and even more preferably 200 μm or more. Then, it is preferably 2,000 μm or less, more preferably 1,500 μm or less, and further preferably 1,000 μm or less.
For example, in the case of FIG. 6 in which a plurality of recesses exist, the edge-to-edge distance of the recess indicates the shortest distance between the edge of any one recess and the edge of the other recess closest to the recess. Refers to the distance 7f in FIG.
Further, for example, in the case of the grid-shaped recesses shown in FIG. 7, the edge-to-edge distance of the recesses is defined as the edge of any one side of the recess forming the grid and the edge of one side facing the side. It shows the shortest distance among the distances and refers to the distance 7f in FIG.
The shortest pitch between the recesses is preferably 50.0 μm or more, more preferably 100 μm or more, still more preferably 150 μm or more, still more preferably 200 μm or more. Then, it is preferably 2,000 μm or less, more preferably 1,500 μm or less, and further preferably 1,000 μm or less.
For example, in the case of FIG. 6 in which a plurality of recesses exist, the shortest pitch of the recess is the edge and edge of the other recess closest to the recess from the midpoint of the shortest distance between the edges of any one recess. Indicates the shortest distance among the distances to the midpoint of the shortest distance to and, and refers to the distance 7p in FIG.
Further, for example, in the case of the grid-shaped recesses shown in FIG. 7, the shortest pitch of the recesses is the one side from the midpoint of the shortest distance between the edges of the recesses forming one side of the grid. The shortest distance among the distances from the edge of the other concave portion forming one side facing the above to the midpoint of the shortest distance between the edges is shown, and refers to the distance 7p in FIG.

The adhesive strength of the surface of the layer (X) where the recesses are present is appropriately set according to the use of the adhesive sheet, but is preferably 0.25 to 10.00 N / 25 mm, more preferably 0.30 to 8 It is .00 N / 25 mm, more preferably 0.40 to 4.0 N / 25 mm.
In the present specification, the adhesive strength of the pressure-sensitive adhesive layer is the adhesive strength before the layer (X) comes into contact with water, and specifically means a value measured by the method described in Examples.

The thickness of the layer (X) is preferably 5 to 150 μm, more preferably 8 to 100 μm, still more preferably 12 to 70 μm, and even more preferably 15 to 50 μm. However, the thickness of the layer (X) is preferably thicker than the height difference of the recesses.
When the thickness of the layer (X) is 5 μm or more, sufficient adhesive strength can be easily obtained, and unintentional peeling from the adherend at the time of temporary fixing, misalignment of the adherend, and the like can be easily suppressed. On the other hand, when the thickness of the layer (X) is 150 μm or less, the pressure-sensitive adhesive sheet can be easily handled.

<Base material>
Examples of the base material forming material that can be used in one aspect of the present invention include resin, metal, paper material, and the like, and can be appropriately selected depending on the use of the pressure-sensitive adhesive sheet.

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

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

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

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

Further, a primer layer, a sealing layer and the like may be provided on the surface of one or both of the base materials, if necessary.
Examples of the components constituting the primer layer include polyester-based resin, urethane-based resin, polyester-urethane-based resin, acrylic-based resin, and the like, and these resins may be used alone or in combination of two or more. ..
The sealing layer is used to further improve the adhesion between the base material and the layer adjacent to the base material, or to impart rigidity when the base material is a base material that is too flexible such as a paper base material. Provided. The sealing layer is not particularly limited, but for example, a styrene-butadiene copolymer, an acrylic resin, a polyester resin, a polyurethane resin, a polystyrene resin, or the like is used as a main component, and clay or silica is used as necessary. , A layer made of a filler such as calcium carbonate, titanium oxide, zinc oxide or the like added.
When these other layers are provided, their thicknesses are independently, preferably 0.05 to 30 μm, more preferably 0.1 to 5 μm, still more preferably 0.1 to 1 μm, still more preferably 0. It is 1 to 0.5 μm.
The base material that can be used in the present invention includes, if desired, as an additive for the base material, for example, an ultraviolet absorber, a light stabilizer, an antioxidant, and an antistatic agent, as long as the effects of the present invention are not impaired. Agents, slip agents, antiblocking agents, colorants and the like may be contained.

The thickness of the base material is appropriately set according to the use of the pressure-sensitive adhesive sheet, but is preferably 5 to 250 μm, more preferably 10 to 200 μm, and further preferably 25 to 150 μm from the viewpoint of handleability and economy. ..

<Release material>
As the release material that can be used in one aspect of the present invention, a release sheet that has undergone double-sided release treatment, a release sheet that has undergone single-sided release treatment, or the like is used. Examples thereof include those coated with.
Examples of the base material for the release material include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin, and plastic films such as polyolefin resin films such as polypropylene resin and polyethylene resin.
Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins, long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins.

Then, as described above, for the purpose of forming the concave portion on the pressure-sensitive adhesive layer (X), it is also referred to as a release material having a convex portion shape formed on the release-treated surface (hereinafter, also referred to as a "release material having a convex portion". ) Is preferable, and from the viewpoint of facilitating the maintenance of the concave shape of the layer (X) during storage of the adhesive sheet or the like, a convex portion paired with the concave portion of the layer (X) is formed on the peeling surface. It is more preferably a release material.
The "convex portion" defined in the present specification refers to a raised portion having a height difference.
The shape of the convex portion can be formed, for example, by transferring the shape engraved on the peripheral surface of the emboss roll onto the peeled surface by embossing.
Further, for example, the convex portion can be formed by using a printing technique such as a screen printing method.

Further, as the shape of the convex portion, for example, a shape paired with the concave portion of the layer (X) can be mentioned, and a preferred embodiment thereof will be described as a preferred embodiment in the description of the concave portion of the layer (X). Since the shape is paired with the recessed portion, detailed description here will be omitted.
Further, for example, the preferred embodiments of "the cross-sectional shape of the concave portion when the layer (X) is cut in the thickness direction" and "the shape of the concave portion when the layer (X) is viewed in a plan view" are similarly "peeled". This is the same as the preferred embodiment of "the cross-sectional shape of the convex portion when the material is cut in the thickness direction" and "the shape of the convex portion when the release material is viewed in a plan view".

Further, as a preferable range of the "height difference and width of the convex portion" existing on the surface of the release material, the height of the convex portion capable of forming the "height difference and width of the concave portion" existing on the surface of the layer (X) described above is defined. It can also be called difference and width. Similarly, as a preferable range of the "distance between the bases of the convex portions and the shortest pitch" existing on the surface of the release material, the "distance between the edges of the concave portion and the shortest pitch" existing on the surface of the layer (X) described above are formed. It can also be said that the distance between the foot of the convex portion and the shortest pitch that can be formed.
Therefore, the preferable ranges of the "height difference and width of the convex portion" and the "distance between the bases of the convex portions and the shortest pitch" are not particularly limited as long as the effects of the present invention are not impaired. It may be in the range shown below.

The height difference of the convex portion is preferably 0.5 μm or more, more preferably 1.0 μm or more, further preferably 3.0 μm or more, and preferably 50.0 μm or less, more preferably 30.0 μm. Below, it is more preferably 25.0 μm or less, and even more preferably 20.0 μm or less.
Similarly, the width of the convex portion is preferably 150 μm or less, more preferably 100 μm or less, still more preferably 75.0 μm or less, still more preferably 50.0 μm or less, still more preferably 35.0 μm or less, still more preferably. Is 30.0 μm or less. The lower limit of the width of the recess is not particularly limited, but is preferably 1.0 μm, more preferably 3.0 μm, and even more preferably 5.0 μm.
The height difference and width of the convex portion are values measured by using the method described in Examples. For example, the distance 4h shown in FIG. 8 corresponds to the height difference of the convex portion 4a. Further, the distance 4w shown in FIG. 8 corresponds to the width of the convex portion. As an example, a cross-sectional image of the convex portion 4a shown in FIG. 10, which is an image of a scanning electron microscope (SEM) taken by the method described in the example, will be described in FIG. The distance 4h corresponds to the height difference of the convex portion, and the distance 4w corresponds to the width of the convex portion.

The distance between the foot of the convex portion is preferably 50.0 μm or more, more preferably 100 μm or more, still more preferably 150 μm or more, and even more preferably 200 μm or more. Then, it is preferably 2,000 μm or less, more preferably 1,500 μm or less, and further preferably 1,000 μm or less.
For example, if the concave portion of FIG. 6 is replaced with a convex portion (assuming that FIG. 6 is a surface having a convex portion of the release material), the distance between the bases of the convex portion is the foot of an arbitrary convex portion and the corresponding. The shortest distance between the convex portion and the foot of the nearest convex portion is shown, and refers to the distance 7f in FIG.
Further, for example, if the grid-like concave portion shown in FIG. 7 is replaced with a convex portion (assuming that FIG. 7 is a surface having a convex portion of the release material), the distance between the bases of the convex portion is the lattice. It indicates the shortest distance among the distances between the foot of any one side of the formed convex portion and the foot of one side facing the side, and refers to the distance 7f in FIG.
The shortest pitch between the convex portions is preferably 50.0 μm or more, more preferably 100 μm or more, still more preferably 150 μm or more, and even more preferably 200 μm or more. Then, it is preferably 2,000 μm or less, more preferably 1,500 μm or less, and further preferably 1,000 μm or less.
For example, if the concave portion of FIG. 6 is replaced with a convex portion (assuming that FIG. 6 is a surface having a convex portion of the release material), the shortest pitch of the convex portion is the foot of any one convex portion. The shortest distance from the midpoint of the shortest distance to the foot to the midpoint of the shortest distance between the foot of the other convex part closest to the convex portion and the foot is shown, and refers to the distance 7p in FIG. ..
Further, for example, when the lattice-shaped concave portion shown in FIG. 7 is replaced with a convex portion (assuming that FIG. 7 is a surface having a convex portion of the release material), the shortest pitch of the convex portion is 1 of the lattice. From the midpoint of the shortest distance between the base and the foot of the convex portion forming the side, the middle of the shortest distance between the base and the foot of the other convex portion forming one side facing the one side. It indicates the shortest distance among the distances to the point, and refers to the distance 7p in FIG.
As an example, if the convex portion 4a shown in FIG. 12, which is an image of a scanning electron microscope (SEM) taken by the method described in the example, is viewed in a plan view, it will be described in FIG. The middle distance 4p corresponds to the shortest pitch of the convex portion, and the distance 4w corresponds to the width of the convex portion.

The thickness of the release material is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 5 to 250 μm, more preferably 30 to 200 μm, and further preferably 50 to 150 μm.

The total thickness of the pressure-sensitive adhesive sheet (total thickness of each layer, excluding the release material) is appropriately set according to the use of the pressure-sensitive adhesive sheet, but is preferably 30 μm or more, more preferably 70 μm or more, and further. It is preferably 95 μm or more, and preferably 300 μm or less, more preferably 200 μm or less, still more preferably 170 μm or less, still more preferably 150 μm or less.

<Other adhesive layer (Z)>
The pressure-sensitive adhesive sheet according to one aspect of the present invention may have a pressure-sensitive adhesive layer (Z) other than the above-mentioned layer (X) as long as the effects of the present invention are not impaired.
As one aspect of the pressure-sensitive adhesive sheet, for example, as described above, in the pressure-sensitive adhesive sheet 30 shown in FIG. 3, one of the two layers (X) 2 does not have a recess 1 on the surface of the layer (X) 2. Other aspects of the pressure-sensitive adhesive layer (Z) other than the above can be mentioned. Moreover, the aspect of the pressure-sensitive adhesive sheet 50 shown in FIG. 5 can be mentioned.
The pressure-sensitive adhesive layer (Z) other than the layer (X) can be appropriately selected depending on the use of the pressure-sensitive adhesive sheet, and is not particularly limited as long as the effects of the present invention are not impaired. Examples of the adhesive resin contained in the other adhesive layer include rubber resins such as acrylic resins, urethane resins, and polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins. And so on.
These adhesive resins may be used alone or in combination of two or more.
When these adhesive resins are copolymers having two or more kinds of structural units, the form of the copolymer may be any of a block copolymer, a random copolymer, and a graft copolymer. There may be.
Further, when the pressure-sensitive adhesive sheet according to one aspect of the present invention has a pressure-sensitive adhesive layer (Z), the above-mentioned release material may be provided on the exposed surface of the pressure-sensitive adhesive layer (Z).

[Manufacturing method of adhesive sheet]
The method for producing the pressure-sensitive adhesive sheet is not particularly limited as long as the pressure-sensitive adhesive layer (X) having recesses on at least one surface can be formed, but preferably at least the following steps (1) and (2). ) Is mentioned.
Step (1): An acrylic polymer (A) having a carboxy group, a neutralizing agent (B), and a cross-linking agent (C) are included on the surface of the release material having the convex portion where the convex portion exists. Step of applying acrylic pressure-sensitive adhesive composition to form a coating film Step (2): A pressure-sensitive adhesive layer in which the coating film formed in step (1) is dried and recesses are present on the surface on the release material side. Step of forming (X) to obtain an adhesive sheet

In the following description, the mode of the pressure-sensitive adhesive layer (X), the release material and the base material, the mode of the acrylic pressure-sensitive adhesive composition forming the layer (X), and the mode of the obtained pressure-sensitive adhesive sheet are the above-mentioned pressure-sensitive adhesive sheets. Since the same is true of the embodiments described in the section of, and the preferred embodiments thereof are also the same, detailed description thereof will be omitted.

By using a release material having a convex portion in the step (1), the convex portion is formed in the process of drying the coating film made of the acrylic pressure-sensitive adhesive composition in the step (2) to form the pressure-sensitive adhesive layer (X). The part shape can be transferred onto the surface of the layer (X) to form recesses in the layer (X).
When the pressure-sensitive adhesive composition is applied onto a release material having a convex portion, the pressure-sensitive adhesive composition may be further mixed with an organic solvent to dilute it, and used as a solution form of the pressure-sensitive adhesive composition. good.
Examples of the organic solvent used include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol and the like.
As these organic solvents, the organic solvent used in the production of each component contained in the pressure-sensitive adhesive composition may be used as it is, or one or more other organic solvents may be added.

The solution of the pressure-sensitive adhesive composition can be applied onto the release material by a known coating method to form a coating film.
Examples of the coating method include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method and the like.

In the step (2), the coating film formed in the step (1) is dried. As described above, the recesses of the layer (X) are formed in the process of drying the coating film to form the pressure-sensitive adhesive layer (X).
The drying temperature in the step (2) is not particularly limited as long as the layer (X) can be formed, but is preferably 80 to 150 ° C., more preferably 90 to 140 ° C., and even more preferably 95 to 130 ° C. The drying time is not particularly limited as long as the layer (X) can be formed, but is preferably 30 seconds to 5 minutes, and more preferably 1 minute to 3 minutes.

[Use of adhesive sheet]
The adhesive sheet, which is one aspect of the present invention, has sufficient adhesive strength when attached to the adherend, but when peeled from the adherend, it is self-peeled by contacting with water in a short time. As long as an adherend that can come into contact with water is used, it can be applied to all applications.
The adherend is not particularly limited, but a brittle material can be mentioned as a preferred embodiment thereof from the viewpoint that the pressure-sensitive adhesive sheet has self-peeling property and the load applied to the adherend can be reduced. A preferred example of the above is a wafer for an electronic device, which will be described later.
Further, the adhesive sheet is suitable from the viewpoint that the adhesive sheet has self-peeling property and can be expected to suppress or prevent defects such as contamination, deformation, and breakage of the adherend caused by the adhesive sheet. One embodiment includes materials for electronic devices.
Examples of the material for electronic devices include chips for electronic devices such as semiconductor chips, wafers for electronic devices such as semiconductor wafers, compound semiconductors, packages for electronic devices such as semiconductor packages, electronic components, sapphire substrates, displays, and panels. Examples include a substrate. Of these, wafers for electronic devices are more preferred.

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

Further, since the pressure-sensitive adhesive sheet, which is one aspect of the present invention, can be self-peeled, it can be expected to suppress and prevent defects such as contamination, deformation, and breakage of the adherend caused by the pressure-sensitive adhesive sheet. .. Therefore, as an application of the adhesive sheet, which is one aspect of the present invention, in addition to materials for electronic devices, for example, protective film applications such as window films, protective / design-imparting applications such as wallpaper and wrapping films, and returnable labels Various uses such as various label uses such as, use when affixing temporary notices, etc. can be mentioned.
Further, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is a pressure-sensitive adhesive sheet having the above-mentioned layer (X) having a continuous concave shape, air bleeding property and appearance when the pressure-sensitive adhesive sheet is attached to an adherend are required. It can also be suitably used for applications such as identification, decoration, paint masking, and surface protection of metal plates and the like. More specifically, it can be suitably used, for example, as a coating substitute tape; a marking film; and a vehicle sticking tape (for example, a decorative tape for decorating the exterior or interior of an automobile, a blackout tape, etc.); ..

Further, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is used as, for example, a double-sided pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet is composed of only a single-layer pressure-sensitive adhesive layer, and the recess is the surface of one side of the layer (X). If it is present only in, or if there is a layer (X) having two pressure-sensitive adhesive layers and having a recess on only one surface, the surface having the recess is attached to either adherend. It is possible to appropriately select whether or not to use the product. For example, the layer (X) may be attached to the adherend side to be peeled off with a lower load, and for example, another adhesive layer is provided for a purpose different from that of the layer (X). In the case of other pressure-sensitive adhesive layers (for example, in the case of a pressure-sensitive adhesive layer having lower contamination), the surface to be attached to each adherend may be selected according to the effect of each layer.

For example, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is used as a double-sided pressure-sensitive adhesive sheet for processing and inspection of an adherend, the pressure-sensitive adhesive layers on both sides can be used from the viewpoint of improving the processability and inspectability of the adherend. The adherend can be attached to either one of the pressure-sensitive adhesive layers, and the support can be attached to either of the other pressure-sensitive adhesive layers. In this case, as described above, the layer (X) may be used as one of the pressure-sensitive adhesive layers, and both pressure-sensitive adhesive layers may be used as the layer (X).
By fixing the adherend to the support via an adhesive sheet, vibration, misalignment, and adherence of the adherend when one or more selected from processing and inspection are applied to the adherend. It is preferable because it is possible to suppress damage and the like when the body is a brittle adherend such as a brittle material, and improve the processing accuracy and processing speed as well as the inspection accuracy and inspection speed.
At this time, when double-sided adhesive using only one of the pressure-sensitive adhesive layers as the layer (X) is used, the type of adherend to be processed and / or inspected, the type of processing and / or inspection method, etc. Depending on the situation, the adherend to be processed and / or inspected may be attached to the layer (X) side, and the support may be attached to the other adhesive layer for use, or the support may be attached to the layer. The adherend which is attached to the (X) side and is the object of processing and / or inspection may be attached to the other adhesive layer for use.
When a double-sided adhesive sheet having different layers (X) on both sides is used, either layer (X) may be similarly attached to an adherend to be processed and / or inspected.

As described above, the adherend to be processed and / or inspected is preferably a material for an electronic device. Therefore, for example, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is used as a double-sided pressure-sensitive adhesive sheet for processing and / or inspection of the material for electronic devices, it is suitable for temporarily fixing the material for electronic devices to a support. Can be used.
The material of the support takes into consideration required characteristics such as mechanical strength and heat resistance according to the type of adherend to be processed and / or inspected, the type of processing and / or inspection method, and the like. Above, it may be selected as appropriate.
For example, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is used as a double-sided pressure-sensitive adhesive sheet for processing and / or inspection of a material for an electronic device, the material of the support is, for example, a metal material such as SUS; glass. , Non-metallic inorganic materials such as silicon wafers; resin materials such as epoxy resins, ABS resins, acrylic resins, engineering plastics, super engineering plastics, polyimide resins, polyamideimide resins; composite materials such as glass epoxy resins, etc. Of these, SUS, glass, and silicon wafers are preferable.
Examples of the engineering plastic include nylon, polycarbonate (PC), polyethylene terephthalate (PET) and the like.
Examples of the super engineering plastic include polyphenylene sulfide (PPS), polyethersulfone (PES), and polyetheretherketone (PEEK).

Further, when the adhesive sheet according to one aspect of the present invention is used as a double-sided adhesive sheet for processing and / or inspection of the material for an electronic device, the support is attached to the entire surface of the adhesive surface of the adhesive layer to be attached. It is preferable to be done. Therefore, the area of the surface of the support on the side to be attached to the adhesive surface of the adhesive layer is preferably equal to or larger than the area of the adhesive surface of the adhesive layer. Further, the surface of the support on the side to be attached to the adhesive surface of the adhesive layer is preferably flat.
The shape of the support is not particularly limited, but is preferably plate-shaped.
The thickness of the support may be appropriately selected in consideration of the required characteristics, but is preferably 20 μm or more and 50 mm or less, and more preferably 60 μm or more and 20 mm or less.

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

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

<Thickness of base material layer and release material>
The measurement was performed using a constant pressure thickness measuring device (manufactured by Teclock Co., Ltd., model number: "PG-02J", standard: JIS K6783-1994, Z1702-1994, Z1709-1995).
The thickness of the embossed release material is the distance from the smooth surface of the release material to the portion where the convex portion of the embossed surface is formed. For example, the distance 4t shown in FIG. 8 corresponds to the thickness of the release material.

<Thickness of each layer in the adhesive sheet>
The pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples are perpendicular to the surface parallel to the surface of the base material layer (corresponding to a portion where no recess is formed). The cross section in the thickness direction cut in the direction was observed using a scanning electron microscope (manufactured by Hitachi, Ltd., product name "S-4700"), and the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) were observed. The thickness of each was measured.
The thickness of the pressure-sensitive adhesive layer (X) was defined as the distance from the surface of the pressure-sensitive adhesive layer in contact with the base material to a portion of the surface opposite to the base material where no recess was formed.
For example, the distance 2t shown in FIG. 1 corresponds to the thickness of the layer (X).
Further, the thickness of the pressure-sensitive adhesive layer (Z) described later was also measured in the same manner.

<Height difference, width and shortest pitch of recesses in layer (X)>
The height difference and width of the recesses existing on the surfaces of the pressure-sensitive adhesive layers (X) (layers (X1) and (X2) opposite to the base material of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples are scanning electron electrons. The cross section of the adhesive sheet was observed using a microscope (manufactured by Hitachi, Ltd., product name "S-4700"), and measurement was performed using the measurement function of image analysis software for a scanning electron microscope.
Note that FIG. 9 shows an SEM image when the height difference of the recess on the layer (X1) is measured in Example 1. In the case of the first embodiment, the height difference and the width value correspond to the distances of 1h and 1w shown in FIG.
Further, FIG. 11 shows an SEM image when the shortest pitch of the recesses on the layer (X1) is measured in Example 1. In the case of the first embodiment, the value of the shortest pitch corresponds to the distance of 7p shown in FIG. Note that 1w shown in FIG. 11 corresponds to the width of the recess.

<Height difference, width and shortest pitch of the convex part of the release material>
A scanning electron microscope (manufactured by Hitachi, Ltd., product name "S-4700") was used for the height difference, width, and shortest pitch of the convex portions existing on the surface of the release material on the pressure-sensitive adhesive layer side of the examples. The cross section was observed and measured using the measurement function of the image analysis software for the scanning electron microscope.
Note that FIG. 10 shows an SEM image when the height difference of the convex portion of the release material 1 is measured. The height difference and the width value of the convex portion of the release material 1 correspond to the distances of 4h and 4w shown in FIG. 10, respectively.
Further, FIG. 12 shows an SEM image when the shortest pitch of the convex portion of the release material 1 is measured. The value of the shortest pitch of the convex portion of the release material 1 corresponds to the distance of 4p shown in FIG. Note that 4w shown in FIG. 12 corresponds to the width of the convex portion.

<Evaluation of water contact peelability of adhesive sheet>
For evaluation of water contact peelability in which the pressure-sensitive adhesive layer (X2) is replaced with a pressure-sensitive adhesive layer (Z) having no recess formed as follows in each of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples described later. Each double-sided adhesive sheet was prepared.
Specifically, as an acrylic polymer for the pressure-sensitive adhesive layer (Z), an acrylic system obtained by copolymerizing 77 parts by mass of n-butyl acrylate, 20 parts by mass of methyl methacrylate, and 3 parts by mass of 2-hydroxyethyl acrylate. A copolymer (mass average molecular weight = 500,000) was prepared.
Next, 5 parts by mass (active component ratio) of trimethylolpropane adducttoluene isocyanate (manufactured by Tosoh Corporation, product name "Coronate (registered trademark) L") was added to 100 parts by mass of the acrylic copolymer as a cross-linking agent. The mixture was added to prepare an acrylic pressure-sensitive adhesive composition, further mixed with toluene, diluted, and stirred for 30 minutes to prepare a solution of the acrylic pressure-sensitive adhesive composition.
Next, a solution of the acrylic pressure-sensitive adhesive composition is applied onto the embossed surface of the release material 4 described later using an applicator, and dried at a drying temperature of 100 ° C. for 2 minutes to provide a pressure-sensitive adhesive layer having no recesses. (Z) was formed so as to have a thickness of 20 μm.
Then, the pressure-sensitive adhesive layer (Z) is placed on the exposed surface of the PET base material of the laminate composed of the pressure-sensitive adhesive layer (X1) and the PET base material produced in the same manner as in each of the examples and the comparative examples described later. The exposed surfaces were laminated to prepare a double-sided adhesive sheet for evaluation of water contact peelability.
A test piece was prepared by cutting each of the prepared double-sided pressure-sensitive adhesive sheets for evaluation of water contact peelability into a size of 50 mm in length (MD) and 50 mm in width (TD).
In addition, two glass plates (manufactured by Corning Inc., product name "Eagle XG (registered trademark)", size: length 50 mm x width 50 mm x thickness 2 mm) were prepared.
Then, only the release material on the pressure-sensitive adhesive layer (X1) side is removed, and one of the glass plates is placed on the surface of the exposed pressure-sensitive adhesive layer (X1) on a desktop laminator (manufactured by Fujipla Co., Ltd., product name ". LPD3212 ”) was used for pressure bonding at 23 ° C. and a laminating speed of 300 mm / min.
Subsequently, the release material 4 on the pressure-sensitive adhesive layer (Z) side was also removed, and the remaining one of the glass plates was placed on the surface of the exposed pressure-sensitive adhesive layer (Z) with a vacuum laminator (Nikko Materials Co., Ltd.). A water contact peelability evaluation sample was prepared by pressure-bonding and bonding at 60 ° C., 0.2 MPa, and 30 seconds using a product name “V-130” manufactured by the company).
The obtained water contact peelability evaluation sample is immersed in a water tank of pure water at 25 ° C. so that the layer (X1) side faces upward, and the entire surface of the glass plate attached to the layer (X1) side is self-peeled. The time until it was measured was measured. Even if the evaluation sample is placed flat in the water tank, water infiltrates between the self-peeled glass plate and the layer (X1), and there is a difference in the refractive index between the peeled part and the unpeeled part of the evaluation sample. Since it occurs, it was possible to visually confirm the presence or absence of self-peeling even from outside the water tank.
Here, MD in the MD direction is an abbreviation for Machine Direction, and the MD direction means a long direction at the time of molding the adhesive sheet. Further, TD in the TD direction is an abbreviation for Transverse Direction, and the TD direction means the width direction at the time of molding the adhesive sheet. Here, the "MD direction" in the pressure-sensitive adhesive sheet refers to the direction in which the pressure-sensitive adhesive composition is applied when the pressure-sensitive adhesive layer (X1) is formed.

<Adhesive strength of adhesive layer (X1)>
Similar to the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples, single-sided pressure-sensitive adhesive sheets that do not form the pressure-sensitive adhesive layer (X2) were prepared as samples for evaluation of pressure-sensitive adhesive strength. Each of the evaluation samples was cut into a size of 300 mm in length (MD) and 25 mm in width (TD) to prepare a test piece.
Then, the release material on the pressure-sensitive adhesive layer (X1) is removed, and the surface of the exposed pressure-sensitive adhesive layer (X1) is attached to the mirror surface of the silicon mirror wafer with a 2 kg rubber roller based on JIS Z0237: 2000. And pasted together.
Then, after allowing to stand for 20 minutes in an environment of 23 ° C. and 50% RH (relative humidity), the adhesive layer (X1) was subjected to a 180 ° peeling method at a tensile speed of 300 mm / min based on JIS Z0237: 2000. Was peeled off from the silicon mirror wafer, and the adhesive strength of the adhesive layer (X1) was measured.

[Manufacturing of adhesive sheet]

(Preparation of acrylic pressure-sensitive adhesive composition)
Manufacturing example 1
From an acrylic copolymer (n-butyl acrylate (BA) / 2-hydroxyethyl acrylate (2HEA) / acrylic acid (AAc) = 85/12/3 (mass ratio)) which is an acrylic polymer (A) having a carboxy group. Acrylic copolymer having a structural unit derived from the raw material monomer, triethanolamine as a neutralizing agent (B) with respect to 100 parts by mass (active component ratio) of mass average molecular weight (Mw): 400,000). 7 parts by mass and 7 parts by mass (active ingredient ratio) of an epoxy-based cross-linking agent (manufactured by Nagase ChemteX Corporation, product name "Denacol (registered trademark) EX-810") as a cross-linking agent (C). An acrylic pressure-sensitive adhesive composition was prepared, and then toluene was added to dilute the composition, and the mixture was uniformly stirred to prepare a solution of the acrylic pressure-sensitive adhesive composition.

Manufacturing example 2
A solution of the acrylic pressure-sensitive adhesive composition was prepared in the same manner as in Production Example 1 except that triethanolamine was not blended.

(Base material and release material)
Each of the abbreviations shown below represents the following materials.
-PET base material: Polyethylene terephthalate film, manufactured by Toyobo Co., Ltd., product name "Cosmo Shine (registered trademark)", product number "A4300", thickness 50 μm
-Release material 1: Film with silicone peeling treatment on the embossed surface, thickness 139 μm (including convex height), embossed pattern diagonal grid, minimum pattern pitch 250 μm, cross-sectional shape of convex V-shaped, convex Height 9 μm, convex width 20 μm
-Release material 2: Release paper having a resin layer with a silicone peeling treatment on the embossed surface, thickness 143 μm (including the height of the convex part), embossed pattern parallel diagonal lines, the shortest pitch of the pattern 700 μm, cross-sectional shape of the convex part U Character shape, convex height 23 μm, convex width 71 μm
-Release material 3: Release paper having a resin layer with a silicone peeling treatment on the embossed surface, thickness 142 μm (including the height of the convex part), embossed pattern wavy line, cross-sectional shape of the convex part U-shaped, height of the convex part 22 μm, convex width 98 μm
-Release material 4: Polyethylene terephthalate film with silicone release treatment on one side, product name "SP-PET381031", thickness 38 μm, no embossing treatment.

(Creation of adhesive sheet)
Example 1
The solution of the acrylic pressure-sensitive adhesive composition prepared in Production Example 1 is applied onto the embossed surface of the release material 1 using an applicator, and dried at a drying temperature of 100 ° C. for 2 minutes to form a first pressure-sensitive adhesive layer. (X1) was formed. Further, the PET base material was laminated on the exposed surface of the pressure-sensitive adhesive layer (X1).
Further, a second pressure-sensitive adhesive layer (X2) is formed on the embossed surface of the separately prepared release material 1 in the same manner as described above by using the solution of the acrylic pressure-sensitive adhesive composition prepared in Production Example 1. bottom.
Then, the exposed surface of the pressure-sensitive adhesive layer (X2) is bonded onto the exposed surface of the PET base material bonded to the pressure-sensitive adhesive layer (X1), and the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer (X) on both sides. Got

Examples 2 and 3 and Comparative Example 1
As the release material, the following release materials are used in the same manner as in Example 1 except that the release materials shown in Table 1 below are used and the thicknesses of the pressure-sensitive adhesive layers (X1) and (X2) are changed. Each adhesive sheet shown in Table 1 was obtained.

Comparative Example 2
A pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive composition prepared in Production Example 2 was used as the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layers (X1) and (X2).

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

From Table 1, the pressure-sensitive adhesive sheets of Examples 1 to 3 are excellent in water contact peelability, and are compared with the pressure-sensitive adhesive sheets of Comparative Examples 1 and 2 until the pressure-sensitive adhesive sheet is self-peeled from the adherend after being immersed in water. It was confirmed that the time was significantly reduced. It was also confirmed that it had sufficient adhesive strength to hold the adherend before it was immersed in water.
Since the pressure-sensitive adhesive sheets of Examples 1 to 3 have recesses on the surface to which the pressure-sensitive adhesive layer (X) (layer (X1) and layer (X2)) is attached to the adherend, when the pressure-sensitive adhesive sheet is viewed in a plan view, When immersed in water, water can easily penetrate from the outer edge portion of the adhesive sheet to the central portion of the adhesive sheet along the concave portion. As a result, it is considered that the time required for water contact peeling was significantly shortened.
On the other hand, in Comparative Example 1, since there are no recesses on the sticking surface of the pressure-sensitive adhesive layer (layer (X1) and layer (X2)), after the pressure-sensitive adhesive sheet is immersed in water, each pressure-sensitive adhesive layer and the adherend are used. Water can enter the interface of the adhesive sheet only from the outer edge of the adhesive sheet. Therefore, it is considered that it took a long time for water to infiltrate the interface between each pressure-sensitive adhesive layer and the adherend to the extent that the pressure-sensitive adhesive sheet can be self-peeled from the adherend.
Further, in Comparative Example 2, although there are recesses on the sticking surface of the pressure-sensitive adhesive layers (layer (X1) and layer (X2)), the pressure-sensitive adhesive composition forming each pressure-sensitive adhesive layer contains the neutralizing agent (B). Since it is not contained, the time required for water contact peeling is longer than that of the adhesive sheets of Examples 1 to 3.
The result is that the pressure-sensitive adhesive layer (X) contained in the pressure-sensitive adhesive sheets of Examples 1 to 3 is a layer formed from the pressure-sensitive adhesive composition containing the components (A) to (C), and thus the pressure-sensitive adhesive layer (X). ) Is improved, and water is more likely to infiltrate the interface between the layer (X) and the adherend, which is considered to indicate that the water contact peelability is improved.
Further, the shortest pitch of the recesses formed on the surface of the pressure-sensitive adhesive layer (X) of the pressure-sensitive adhesive sheet of Example 1 is 250 μm, and the recesses formed on the surface of the pressure-sensitive adhesive layer (X) of the pressure-sensitive adhesive sheet of Example 2 It was also confirmed that the shortest pitch of was 700 μm.
Further, with respect to the adhesive sheets of Examples 1 to 3, before immersing the evaluation sample prepared in the water contact peelability evaluation in the water tank, an optical digital microscope (manufactured by KEYENCE CORPORATION, product name "Digital Microscope VHX-5000"". ) Was used to view the surfaces of the pressure-sensitive adhesive layers (X1) and (X2) in a plan view (magnification: 100 times). As a result, both the pressure-sensitive adhesive layers (X1) and (X2) of the pressure-sensitive adhesive sheets of Examples 1 to 3 have the recesses that are continuously bonded from any one part of the surface contour to the other part of the contour. It was also confirmed that there were multiple. It was also confirmed that the continuously bonded recesses formed a recess that was continuously bonded from any one side to the other side of the surface of the pressure-sensitive adhesive layer (X).

The adhesive sheet, which is one aspect of the present invention, has sufficient adhesive strength when attached to the adherend, but when peeled from the adherend, it is self-peeled by contacting with water in a short time. As long as an adherend that can come into contact with water is used, it can be applied to all applications.
For example, it can be used as various temporary fixing sheets used in the manufacturing process of materials for electronic devices as described above.
In addition to electronic device applications, the adhesive sheet according to one aspect of the present invention can be used for various purposes such as the above-mentioned protective film applications such as window films, protective / design-imparting applications such as wallpaper and wrapping films, and returnable labels. Various uses such as label use and use for attaching temporary notices and the like can be mentioned.
Further, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer (X) having the above-mentioned continuous concave shape, for example, the above-mentioned identification, decoration, paint masking, and metal plate. It can also be suitably used for surface protection such as.

10, 20, 30, 40, 50, 60, 70 Adhesive sheet 100 Water contact peelability evaluation sample 101 of the adhesive sheet in the examples of the present application Adhesive body (glass plate)
1 Recessed portion existing on the surface of the adhesive layer (X) 1h Height difference of the concave portion existing on the surface of the adhesive layer (X) 1w Width of the concave portion existing on the surface of the adhesive layer (X) 2 Adhesive layer (X) )
2a Convex portion of the pressure-sensitive adhesive layer (X) 2t Thickness of the pressure-sensitive adhesive layer (X) 3 Base material 4 Release material 4-1 First release material 4-2 Second release material 4a Adhesive contained in the release material Convex part paired with the concave part of the layer (X) 4h Height difference of the convex part of the release material 4w Width of the convex part of the release material 4p Shortest pitch of the convex part of the release material 4t Thickness of the release material 5 Adhesive Adhesive layer (Z) other than layer (X)
6 Area surrounded by recess 1 7f Distance between edges of recess 1 7p Shortest pitch of recess 1

Claims (11)

It has a pressure-sensitive adhesive layer (X) formed of an acrylic pressure-sensitive adhesive composition containing an acrylic polymer (A) having a carboxy group, a neutralizing agent (B), and a cross-linking agent (C), and is a pressure-sensitive adhesive layer. An adhesive sheet having recesses on at least one surface of (X). The pressure-sensitive adhesive sheet according to claim 1, wherein the component (B) is an amine compound. The component (A) contains a structural unit (a2) derived from the monomer (am2) containing a carboxy group in an amount of 0.1 to 20% by mass based on 100% by mass of all the structural units constituting the component (A). , The adhesive sheet according to claim 1 or 2. The content of the component (A) in the acrylic pressure-sensitive adhesive composition is 75 to 95% by mass in the total amount (100% by mass of the active ingredient) of the acrylic pressure-sensitive adhesive composition, claim 1 to 3. The adhesive sheet according to any one item. Claims 1 to 4 indicate that the content of the component (B) in the acrylic pressure-sensitive adhesive composition is 0.05 to 10 parts by mass with respect to the total amount of the component (A) (100 parts by mass of the active ingredient). The adhesive sheet according to any one of the above. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the component (C) is at least one selected from an epoxy-based cross-linking agent and a metal chelate-based cross-linking agent. Claims 1 to 6 indicate that the content of the component (C) in the acrylic pressure-sensitive adhesive composition is 0.05 to 10 parts by mass with respect to the total amount of the component (A) (100 parts by mass of the active ingredient). The adhesive sheet according to any one of the above. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the height difference between the recesses is 0.5 μm or more. Any one of claims 1 to 8, wherein when the pressure-sensitive adhesive layer (X) is viewed in a plan view, the recess is continuously bonded from one part of the contour of the surface of the pressure-sensitive adhesive layer (X) to another part. Adhesive sheet as described in the section. The pressure-sensitive adhesive sheet according to any one of claims 1 to 9, wherein the adhesive strength of the surface of the pressure-sensitive adhesive layer (X) where the recesses are present is 0.20 to 10.00 N / 25 mm. The pressure-sensitive adhesive sheet according to any one of claims 1 to 10, which has a base material.

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