JP6978162B2 - Adhesive sheet and manufacturing method of adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet and a method for manufacturing the adhesive sheet.

A general pressure-sensitive adhesive sheet is composed of a base material, a pressure-sensitive adhesive layer formed on the base material, and a release material provided on the pressure-sensitive adhesive layer, if necessary, and is peeled off when used. If a material is provided, the release material is peeled off, and the adhesive layer is brought into contact with the adherend and attached.
By the way, for example, an adhesive sheet having a large attachment area, which is used for identification / decoration, paint masking, surface protection of a metal plate, etc., has an adhesive layer and an adherend when it is attached to an adherend. There is a problem that an air pool is likely to occur between the two, and that portion becomes a "blister", making it difficult for the adhesive sheet to be neatly attached to the adherend.

In order to solve such a problem, for example, in Patent Document 1, a release material having a fine embossed pattern is brought into contact with the surface of the pressure-sensitive adhesive layer, and a groove having a specific shape is formed on the surface of the pressure-sensitive adhesive layer. , A pressure-sensitive adhesive sheet artificially arranged in a predetermined pattern is disclosed.
By using such an adhesive sheet, it is said that the "air pool" generated at the time of attachment to the adherend can be released to the outside through a groove artificially formed on the surface of the adhesive layer. ing.

Japanese Patent Publication No. 2001-507732

However, in an adhesive sheet having an adhesive layer in which grooves having a general specific shape are arranged in a predetermined pattern as described in Patent Document 1 and the like, if the width of the grooves is narrow, it is difficult for air to escape and the width of the grooves is wide. If it is wide, not only the surface base material is dented and the appearance is inferior, but also the adhesive strength is lowered.
Further, since the adhesive sheet has grooves arranged in a predetermined pattern, the adhesive strength at the portion where the groove is arranged is locally inferior, and when the adhesive sheet is attached to the adherend, it peels off from the portion. It can occur.
On the other hand, when the pressure-sensitive adhesive sheet is reattached to the adherend and then peeled off again, the adhesive properties of the pressure-sensitive adhesive sheet are locally different. Therefore, depending on the peeling direction of the pressure-sensitive adhesive sheet, adhesive residue may occur on the adherend. For example, in the case of a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer in which grooves are arranged in a grid pattern, if the pressure-sensitive adhesive sheet is peeled off in an oblique direction, adhesive residue may be generated on the adherend.
Further, when the pressure-sensitive adhesive sheet is punched, the groove arrangement pattern and the punching pattern may overlap with each other. In that case, there is a problem that the depth of cut varies and the adhesive sheet cannot be cut properly.

Further, in general, in order to make it easier to peel off the release material provided on the adhesive sheet, a step of making a cut only in the release material and providing a trigger for release (so-called back cracking process) may be performed. When performing this step, it is common to temporarily peel off the release material from the pressure-sensitive adhesive sheet, make a cut in the release material, and then laminate the release material and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet again.
However, in the adhesive sheet described in Patent Document 1, since the emboss liner is used as the release material, it is difficult to follow the embossing pattern of the release material when the release material and the adhesive layer are laminated again, so that the embossing process is performed. It will be necessary to prepare another release material that has not been subjected to.

Further, in Patent Document 1, in order to form a fine structure in the pressure-sensitive adhesive layer, a method of once applying a pressure-sensitive adhesive to an embossed liner to form a pressure-sensitive adhesive layer and then laminating the pressure-sensitive adhesive layer and a base material ( The so-called transfer coating method) is adopted. However, when a substrate having a low polar surface such as a polyolefin-based substrate is used as the substrate, sufficient adhesion cannot be obtained at the interface between the substrate and the pressure-sensitive adhesive layer by the method.
Moreover, unlike the release material made of paper, it is difficult to form a fine embossed pattern on the pressure-sensitive adhesive layer with the release material made of a resin film.

INDUSTRIAL APPLICABILITY The present invention provides an adhesive sheet having excellent air bleeding property that can easily remove air pools that may occur when attached to an adherend, and also has good adhesive properties, and a method for manufacturing the adhesive sheet. The purpose is to provide.

The present inventor presents on the adhesive surface at least one flat surface having a recess and a region surrounded by a circle having a diameter of 100 μm by observation from the surface side, and the flat surface has a width that can be selected. We have found that an adhesive sheet having a resin layer having an irregular shape can solve the above-mentioned problems, and have completed the present invention.

That is, the present invention provides the following [1] to [19].
[1] A pressure-sensitive adhesive sheet having a resin layer on a base material or a release material, and at least the surface (α) of the resin layer on the side opposite to the side on which the base material or the release material is provided has adhesiveness. hand,
On the surface (α) of the resin layer, there is one or more flat surfaces (f1) having a width that can be selected from the recess and the range surrounded by a circle having a diameter of 100 μm by observation from the surface (α) side. An adhesive sheet having an irregular shape on the flat surface.
[2] The pressure-sensitive adhesive sheet according to the above [1], wherein one or more flat surfaces (f2) having an area of ^{0.2 mm 2} or more are present on the surface (α) of the resin layer.
[3] In a region (D) of 8 mm in length × 10 mm in width arbitrarily selected on the surface (α), 70 to 99.99% with respect to 100% of the total area of the recesses existing in the region (D). The adhesive sheet according to the above [1] or [2], wherein the recess having the area of is present.
[4] A plurality of flat surfaces exist in an arbitrarily selected area (D) of 8 mm in length × 10 mm in width on the surface (α), and the relative skewness is added from the smaller area of the plurality of flat surfaces. The skewness Sk value with respect to the normal distribution curve of each area and frequency of one or more flat surfaces (S) excluding the flat surface having a cumulative relative frequency of 30% or less is 1.0 or more. 3] The adhesive sheet according to any one of.
[5] The adhesive sheet according to the above [4], wherein the kurtosis Ku value with respect to the normal distribution curve of the area and frequency of each of one or more flat surfaces (S) is 1.8 or more.
[6] The pressure-sensitive adhesive sheet according to any one of [1] to [5] above, wherein a plurality of the flat surfaces are present on the surface (α), and the positions where the plurality of flat surfaces are present do not have periodicity.
[7] The pressure-sensitive adhesive sheet according to any one of [1] to [6], wherein the recess has a height difference of 0.5 μm or more at the maximum.
[8] The pressure-sensitive adhesive sheet according to any one of [1] to [7], wherein the recess is not formed by using a release material having an embossed pattern.
[9] The pressure-sensitive adhesive sheet according to any one of [1] to [8], wherein the resin layer contains a resin portion (X) containing a resin as a main component and a fine particle portion (Y) composed of fine particles.
[10] The pressure-sensitive adhesive sheet according to the above [9], wherein the resin layer has a mass retention rate of 3 to 90% by mass after heating at 800 ° C. for 30 minutes.
[11] The pressure-sensitive adhesive sheet according to the above [9] or [10], wherein the resin contained in the resin portion (X) contains a pressure-sensitive adhesive resin.
[12] The pressure-sensitive adhesive sheet according to any one of [9] to [11] above, wherein the resin portion (X) further contains one or more selected from a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent.
[13] The pressure-sensitive adhesive sheet according to any one of [9] to [12] above, wherein the fine particles are one or more selected from silica particles, metal oxide particles, and smectite.
[14] The pressure-sensitive adhesive sheet according to any one of [9] to [13], wherein the surface (β) of the resin layer on the side provided with the base material or the release material has adhesiveness.
[15] The resin layer is a layer (Xβ) mainly containing a resin portion (X) and a layer (Y1) containing 15% by mass or more of a particle portion (Y) from the side where the base material or the release material is provided. The pressure-sensitive adhesive sheet according to any one of [1] to [14] above, which is a multilayer structure in which layers (Xα) mainly containing a resin portion (X) are laminated in this order.
[16] The layer (Xβ) is a layer formed from a composition (xβ) containing a resin and having a fine particle content of less than 15% by mass.
The layer (Y1) is a layer formed from the composition (y) containing 15% by mass or more of fine particles.
The pressure-sensitive adhesive sheet according to the above [15], wherein the layer (Xα) is a layer formed of a composition (xα) containing a resin and having a fine particle content of less than 15% by mass.
[17] A method for producing an adhesive sheet according to any one of the above [1] to [16], which comprises at least the following steps (1) and (2).
Step (1): A coating film (x') containing a resin and having a fine particle content of less than 15% by mass (x), and a coating film (y) containing 15% by mass or more of fine particles. Step of forming (y') Step (2): Step of simultaneously drying the coating film (x') and the coating film (y') formed in the step (1) [18] The pressure-sensitive adhesive sheet according to the above [17]. A method for producing an adhesive sheet, which comprises at least the following steps (1A) and (2A).
Step (1A): A coating film (xβ') comprising a composition (xβ) containing a resin and having a fine particle content of less than 15% by mass on a substrate or a release material, and a composition containing 15% by mass or more of the fine particles. A coating film (y') composed of a substance (y) and a coating film (xα') composed of a composition (xα) containing a resin and having a fine particle content of less than 15% by mass are laminated and formed in this order. Step Step (2A): Step of simultaneously drying the coating film (xβ'), the coating film (y'), and the coating film (xα') formed in the step (1A) [19] Adhesion according to the above [17]. A method for producing a sheet, which comprises at least the following steps (1B) and (2B).
Step (1B): A coating film (y) comprising a composition (y) containing 15% by mass or more of the fine particles on a layer (Xβ) mainly containing a resin portion (X) provided on a base material or a release material. Step (2B): Step (1B): Step (2B): Step (1B): Step (2B): Step (1B): Step (2B): Step (1B): ) And the coating film (xα') formed in) at the same time.

The pressure-sensitive adhesive sheet of the present invention has excellent air bleeding property that can easily remove air pools that may occur when the pressure-sensitive adhesive sheet is attached to an adherend, and also has good pressure-sensitive adhesive properties.

It is sectional drawing of the adhesive sheet which shows an example of the structure of the adhesive sheet of this invention. It is a plane schematic diagram of the surface (α) when observed from the surface (α) side of the resin layer of the pressure-sensitive adhesive sheet of this invention. It is sectional drawing of the resin layer which shows an example of the shape on the surface (α) side of the resin layer which the pressure-sensitive adhesive sheet of this invention has. It is sectional drawing which shows an example of the measurement sample for observing the recess and the flat surface from the surface (α) side of the resin layer defined in this invention. (A) Using a digital microscope, a region (D) surrounded by a rectangle of 8 mm in length × 10 mm in width arbitrarily selected on the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet produced in Example 1 is used. It is a binarized image of the image obtained by taking a picture from the surface (α) side. The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. (B) It is a cross-sectional image obtained by observing the cross section of the pressure-sensitive adhesive sheet produced in Example 1 using a scanning microscope. A region (D) surrounded by an arbitrarily selected rectangle of 8 mm in length × 10 mm in width on the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet produced in Example 2 is surfaced (α) using a digital microscope. It is a binarized image of the image obtained by taking a picture from the side). The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. The surface (α) of the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet produced in Example 3 is surrounded by a rectangle of 8 mm in length × 10 mm in width arbitrarily selected, using a digital microscope. It is a binarized image of the image obtained by taking a picture from the side). The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. A region (D) surrounded by an arbitrarily selected rectangle of 8 mm in length × 10 mm in width on the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet produced in Example 4 is surfaced (α) using a digital microscope. It is a binarized image of the image obtained by taking a picture from the side). The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. The surface (α) of the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet prepared in Comparative Example 1 is surrounded by a rectangle of 8 mm in length × 10 mm in width arbitrarily selected, using a digital microscope. It is a binarized image of the image obtained by taking a picture from the side). The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. The surface (α) of the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet produced in Comparative Example 2 is surrounded by a rectangle of 8 mm in length × 10 mm in width arbitrarily selected, using a digital microscope. It is a binarized image of the image obtained by taking a picture from the side). The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. The surface (α) of the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet produced in Comparative Example 3 is surrounded by a rectangle of 8 mm in length × 10 mm in width arbitrarily selected, using a digital microscope. It is a binarized image of the image obtained by taking a picture from the side). The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion. Using a digital microscope, the surface (α) of the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet prepared in Comparative Example 4 surrounded by an arbitrarily selected rectangle of 8 mm in length × 10 mm in width was formed. It is a binarized image of the image obtained by taking a picture from the side). The black portion of the binarized image corresponds to a flat surface, and the white portion corresponds to a concave portion.

In the present invention, for example, the description of "YY containing an XX component as a main component" or "YY mainly composed of an XX component" means that "the component having the highest content among the components contained in YY is the XX component". It means "there is". The specific content of the XX component in the description is usually 50% by mass or more, preferably 65 to 100% by mass, more preferably 75 to 100% by mass, and further, with respect to the total amount of YY (100% by mass). It is preferably 85 to 100% by mass.
Further, in the present invention, for example, "(meth) acrylic acid" means both "acrylic acid" and "methacrylic acid", and other similar terms are also used.
Further, 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 independently combined. For example, from the description of "preferably 10 to 90, more preferably 30 to 60", the "preferable lower limit value (10)" and the "more preferable upper limit value (60)" are combined to form "10 to 60". You can also do it.

[Structure of Adhesive Sheet of the Present Invention]
The pressure-sensitive adhesive sheet of the present invention has a resin layer on a base material or a release material, and at least the surface (α) of the resin layer on the side opposite to the side on which the base material or the release material is provided has adhesiveness. The pressure-sensitive adhesive sheet has a recess and a flat surface on the surface (α).

FIG. 1 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet showing an example of the structure of the pressure-sensitive adhesive sheet of the present invention.
Examples of the pressure-sensitive adhesive sheet according to one aspect of the present invention include a pressure-sensitive adhesive sheet 1a having a resin layer 12 on a substrate 11 as shown in FIG. 1 (a) and a peeling sheet as shown in FIG. 1 (b). An adhesive sheet 1b having a resin layer 12 on the material 21 can be mentioned.

In the pressure-sensitive adhesive sheet of the present invention, at least the surface (α) 12a (hereinafter, also simply referred to as “surface (α)”) of the resin layer 12 on the side opposite to the side on which the base material 11 or the release material 21 is provided is adhesive. The recess 13 and the flat surface 14 are present.
Therefore, from the viewpoint of handleability, as another aspect of the pressure-sensitive adhesive sheet of the present invention, the release material 22 is further provided on the surface (α) 12a of the resin layer 12 with respect to the pressure-sensitive adhesive sheets 1a and 1b shown in FIG. Those having a structure like the pressure-sensitive adhesive sheets 2a and 2b as shown in FIGS. 1 (c) or 1 (d) provided are preferable.

In the pressure-sensitive adhesive sheet of one aspect of the present invention, as shown in FIG. 1, it is preferable that the resin layer 12 includes a resin portion (X) containing a resin and a particle portion (Y) composed of fine particles.
By including the particle portion (Y) in the resin layer 12, the shape retention after sticking can be improved, and when the obtained adhesive sheet is used at a high temperature, the blister resistance is improved. Can be.
Details of the resin portion (X) and the particle portion (Y) are as described later.

Further, in the pressure-sensitive adhesive sheet according to one aspect of the present invention, the surface (β) 12b (hereinafter, also simply referred to as “surface (β)”) of the resin layer 12 on the side where the base material 11 or the release material 21 is provided is also pressure-sensitive. It may have sex.
Since the surface (β) also has adhesiveness, the adhesive sheets 1a and 2a shown in FIGS. 1 (a) and 1 (c) have good adhesion between the resin layer 12 and the base material 11, and FIG. 1 (2). The pressure-sensitive adhesive sheets 1b and 2b shown in b) and (d) can be double-sided pressure-sensitive adhesive sheets.

[Requirements for recesses and flat surfaces existing on the surface (α)]
As shown in FIGS. 1A to 1D, the pressure-sensitive adhesive sheet of the present invention has a recess 13 and a flat surface 14 on the surface (α) 12a of the resin layer 12.
The recess 13 existing on the surface (α) serves as an air discharge passage for allowing the “air pool” generated when the surface (α) of the resin layer of the adhesive sheet of the present invention is attached to the adherend to escape to the outside. Is responsible for.
On the other hand, the flat surface 14 existing on the surface (α) is a surface that comes into direct contact with and adheres to the adherend at the time of bonding to the adherend, and is a portion that affects the adhesive force of the adhesive sheet.

FIG. 2 is a schematic plan view of the surface (α) when observed from the surface (α) side of the resin layer of the pressure-sensitive adhesive sheet of the present invention.
The concave portion existing on the surface (α) of the resin layer is preferably an amorphous recess 13 as shown in FIG. 2, but a fixed concave portion may be present.
However, in one aspect of the present invention, as shown in FIG. 2, it is preferable that one or more amorphous recesses 13 are present on the surface (α) 12a of the resin layer 12, and the amorphous recesses 13 are formed. It is more preferable that there are a plurality of them.
Since the irregular concave portion is present on the surface (α) of the resin layer, it is possible to obtain a pressure-sensitive adhesive sheet having a well-balanced air bleeding property and adhesive properties.
Further, due to the existence of a plurality of irregularly shaped recesses, even when a pressure from a certain direction is applied and the shape of a part of the recesses existing on the surface (α) collapses, the shape of the surface (α) remains. The maintained recess 13 is likely to exist, and it is possible to prevent the air escape path from disappearing.

The length of the recess 13 when the recess 13 existing on the surface (α) is viewed in a plan view is not particularly limited. That is, the recess 13 includes a relatively long groove shape and a relatively short recess shape.

Further, the flat surface existing on the surface (α) of the resin layer is preferably an amorphous flat surface 14 as shown in FIG. 2, but a fixed flat surface may be present.
However, in one aspect of the present invention, as shown in FIG. 2, it is preferable that the shape of the flat surface 14 observed from the surface (α) 12a side of the resin layer 12 is irregular, and the irregular flat surface 14 is It is preferable that one or more are present, and it is more preferable that a plurality of amorphous recesses 13 are present.
The flat surface existing on the surface (α) of the resin layer may include a fixed flat surface together with the amorphous flat surface 14.
Due to the presence of an amorphous flat surface on the surface (α) of the resin layer, the adhesive force is locally increased, unlike the surface of the adhesive layer formed by using a release sheet having a general embossed pattern. The presence of weak spots and spots with inferior air release can be reduced as much as possible. As a result, it is possible to uniformly exhibit excellent air bleeding property and adhesive properties on the surface (α) of the resin layer.

In the present invention, the "indeterminate form" does not have a fixed shape such as a figure capable of drawing the center of a circle or an ellipse, or a polygon, and the shape has no regularity and is similar to each shape. It refers to a shape in which no property is observed, and specifically, the shape of the recess 13 and the flat surface 14 shown in FIG. 2 corresponds to the shape.
On the other hand, examples of "fixed form" that are not "indeterminate form" include circles, ellipses, and polygons. In the present specification, the "polygon" is a figure capable of drawing a diagonal line inside (without protruding to the outside), and the sum of the internal angles is 180 × n (degrees) (n is a natural number). Refers to the figure surrounded by the straight line. The polygon includes a polygon whose corners are curved in a rounded shape.

Further, in the present invention, whether or not there is an "atypical" concave portion or flat surface on the surface (α) of the resin layer is determined from the surface (α) side of the resin layer on the flat surface or the flat surface to be observed. In principle, the shape of the concave portion is visually or observed with a digital microscope (magnification: 30 to 100 times) to make a judgment.
When using a digital microscope, for example, as shown in FIG. 4A, the focal point is gradually moved from above the portion on the surface (α) 12a where a flat surface is considered to exist in the A direction. However, it is appropriate to observe the part that was in focus for the first time as a flat surface.
When the focus is not determined by the above method, as shown in FIG. 4B, a translucent adherend 100 having a smooth surface 100a on the surface (α) 12a of the resin layer is used as much as possible. Affixed with a squeegee so as not to apply a load, and the surface (α) 12a of the resin layer was observed from the W direction through the translucent adherend 100 using a digital microscope, and recesses and flat surfaces were present. You may judge by the method of confirming whether or not it is.
That is, the portion of the surface (α) that is in contact with the smooth surface 100a can be determined as a “flat surface”, and the portion of the surface (α) that is not in contact with the smooth surface 100a can be determined as a “recess”.

However, 1 to 10 regions (D) of 8 mm in length × 10 mm in width arbitrarily selected on the surface (α) are selected, and the shape of the recess or the flat surface existing in each of the selected regions (D) is surfaced. Judgment may be made by visual observation from the (α) side or by observing with a digital microscope (magnification: 30 to 100 times). That is, if an amorphous recess or a flat surface is present in any of the selected regions, it can be considered that "the irregular recess or the flat surface is present on the surface (α)". Similarly, if there are a plurality of amorphous recesses or flat surfaces in any of the selected regions, it can be considered that "there are a plurality of amorphous recesses or flat surfaces on the surface (α)". ..
When observing the region (D), the entire surface of the region (D) selected at a low magnification may be observed at once using a digital microscope.
Further, the selected area (D) may be observed at a high magnification using a digital microscope, but since the observation is performed at a high magnification, the area (D) is larger than the imageable area of the digital microscope. May be. In such a case, the image concatenation function of the digital microscope is used to capture an arbitrarily selected area adjacent to each other to acquire a plurality of adjacent images, and the plurality of images are concatenated to form a concatenated image. A portion surrounded by a rectangle having a length of 8 mm and a width of 10 mm arbitrarily selected from the connected images may be used as the area (D) in the above determination.
In the following description, even when observing the selected area using a digital microscope in order to determine whether or not a certain requirement is satisfied, the requirement is satisfied from the connected image in the same manner as above. You may judge whether or not it is.

In the description of the present specification, examples of the digital microscope used when observing various shapes include the product names "Digital Microscope VHX-1000" and "Digital Microscope VHX-5000" manufactured by KEYENCE CORPORATION. Can be mentioned.
Further, when observing various shapes, a method of directly observing the surface (α) with a digital microscope at the above magnification may be used, and an image is acquired using the digital microscope at the above magnification and shown in the image. A method of visually observing the shapes of the concave portion and the flat portion may also be used.

Further, it is preferable that the shape of the irregular concave portion existing on the surface (α) can be visually visually recognized from the surface (α) side.
Similarly, it is preferable that the shape of the amorphous flat surface existing on the surface (α) can be visually recognized from the surface (α) side.
In the pressure-sensitive adhesive sheets 2a and 2b in which the release material 22 is laminated on the surface (α) 12a of the resin layer 12 as shown in FIGS. 1 (c) or 1 (d), when the release material 22 is removed. , The exposed surface (α) 12a shall be visually observed.

In one aspect of the present invention, the surface (α) may have a fixed recess as well as an amorphous recess 13, as shown in FIG.
However, the area ratio of the amorphous recesses existing on the surface (α) to 100% of the total area of the recesses existing on the surface (α) is preferably 80 to 100%, more preferably 90 to 100%. It is more preferably 95 to 100%, and even more preferably 100%.

Further, in one aspect of the present invention, the area ratio of the recesses existing on the surface (α) to the total area of the surface (α) is preferably 10 to 80%, more preferably 20 to 70%. It is more preferably 30 to 60%, and even more preferably 35 to 55%.

Similarly, in one aspect of the present invention, a fixed flat surface may be present on the surface (α) together with an amorphous flat surface 14 as shown in FIG.
However, the area ratio of the amorphous flat surface existing on the surface (α) to 100% of the total area of the flat surface existing on the surface (α) is preferably 80 to 100%, more preferably 90 to 100. %, More preferably 95-100%, even more preferably 100%.

Further, in one aspect of the present invention, the area ratio of the flat surface existing on the surface (α) to the total area of the surface (α) is preferably 20 to 90%, more preferably 30 to 80%. , More preferably 40-70%, even more preferably 45-65%.

For the above-mentioned "area ratio occupied by the concave portion or the flat surface", an image of the surface (α) is acquired using a digital microscope (magnification: 30 to 100 times), and the image is processed (binar value). It can be calculated by performing the conversion process).
Further, 1 to 10 areas (D) arbitrarily selected on the surface (α) having a length of 8 mm and a width of 10 mm are selected, and an image of the area is obtained using a digital microscope (magnification: 30 to 100 times). Obtained, calculate the value of "area ratio occupied by concave or flat surface" of each region from the image, and calculate the average of the values of the selected regions 1 to 10 on the surface (α) of the resin layer of the target pressure-sensitive adhesive sheet. ) Can also be regarded as the "area ratio occupied by the concave or flat surface".

In one aspect of the present invention, the shapes of the recesses and the flat surface existing on the surface (α) of the resin layer are constant from the viewpoint of forming an adhesive sheet in which various characteristics such as air bleeding and adhesive characteristics are improved in a well-balanced manner. It is preferable that it does not have a shape that serves as a repeating unit.

Further, in one aspect of the present invention, from the viewpoint of forming an adhesive sheet in which various characteristics such as air bleeding and adhesive characteristics are improved in a well-balanced manner, a plurality of recesses are present on the surface (α) of the resin layer, and the plurality of recesses are present. It is preferable that the position where the recess is present does not have periodicity. Further, from the same viewpoint, it is preferable that a plurality of flat surfaces are present on the surface (α) of the resin layer, and the positions where the plurality of flat surfaces are present do not have periodicity.
In the present invention, "the position where a plurality of recesses or flat surfaces are present does not have periodicity" means that the positions where a plurality of recesses or flat surfaces are present are repeated on the surface (α) of the resin layer. It means a state of being irregular (random) without having a pattern.

In addition, it is judged whether or not "the shape of the concave portion and the flat surface does not have a shape that becomes a constant repeating unit", and "the position where the plurality of concave portions or the flat surface exists does not have periodicity". Whether or not it is determined can be determined by the same method as the above-mentioned method of determining "whether or not there is an amorphous concave portion or a flat surface on the surface (α) of the resin layer".

Hereinafter, specific requirements regarding the recesses and flat surfaces existing on the surface (α) will be described.

[Each requirement satisfied by the adhesive sheet of the present invention]
As shown in FIGS. 1A to 1D, the pressure-sensitive adhesive sheet of the present invention has a recess 13 and a flat surface 14 on the surface (α) 12a of the resin layer 12, and these flat surfaces are as follows. It meets the requirements (Ii) and (Iii) of. The observation from the surface (α) side of the resin layer means the surface (α) of the resin layer observed from the A direction side in FIGS. 1 (a) and 1 (b).
Requirement (Ii): A flat surface (f1) having a size that allows a region surrounded by a circle with a diameter of 100 μm (preferably 150 μm, more preferably 200 μm) to be selected by observation from the surface (α) side of the resin layer. ) Is one or more.
-Requirement (Iii): The shape of the flat surface is irregular.

The recess 13 existing on the surface (α) serves as an air discharge passage for allowing the “air pool” generated when the surface (α) of the resin layer of the adhesive sheet of the present invention is attached to the adherend to escape to the outside. Is responsible for.
On the other hand, the flat surface 14 existing on the surface (α) of the resin layer is a surface that comes into direct contact with and adheres to the adherend when it is attached to the adherend, and affects the adhesive strength of the adhesive sheet. It is a place.

A pressure-sensitive adhesive sheet having a grooved pressure-sensitive adhesive layer formed by using a generally designed release sheet with an embossed pattern can be used, for example, in a place where air bleeding property is good but the adhesive force is weak, or vice versa. In addition, there are some places where the adhesive property is excellent but the air bleeding property is inferior.
An adhesive sheet having an adhesive layer having a groove formed by presetting a shape, width, length, number, existing position, etc., has an air bleeding property, an appearance, an adhesive property, and a punching property. It is difficult to improve the properties such as workability in a well-balanced manner, and unevenness occurs depending on the shape and number of grooves in the pressure-sensitive adhesive layer.

On the other hand, in the pressure-sensitive adhesive sheet of the present invention, recesses and flat surfaces satisfying the above requirements (Ii) and (Iii) are formed on the surface (α) of the resin layer to be the surface to be attached to the adherend. , Various characteristics such as air bleeding property and adhesive property required for the adhesive sheet can be improved in a well-balanced manner.
Hereinafter, the details of the requirements (Ii) and (Iii) will be described.

<Requirements (Ii)>
FIG. 2 is a schematic plan view of the surface (α) when observed from the surface (α) side of the resin layer of the pressure-sensitive adhesive sheet of the present invention.
Since the flat surface (f1) is present on the surface (α), the adhesive portion with the adherend on the surface (α) is sufficient, so that the adhesion with the adherend can be improved, and more. It can be an adhesive sheet with high adhesive strength.
Further, in the above embodiment of the present invention, one or more flat surfaces (f1) may be present in an arbitrarily selected region (D) of 8 mm in length × 10 mm in width on the surface (α) of the resin layer. It is preferable that a plurality of the flat surfaces (f1) are present.
In the above embodiment, it is not necessary that all of the flat surfaces existing on the surface (α) or region (D) of the resin layer correspond to the flat surface (f1), and the surface (α) or region (α) or region ( The flat surface existing in D) may include the flat surface (f1).

In a conventional pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer having a convex portion or a streak formed on the surface formed by stringing a pressure-sensitive adhesive layer and a roll for molding has a convex portion existing on a bare surface or a convex portion. It is difficult for a flat surface having a selectable area in the area surrounded by a circle with a diameter of 100 μm to exist in the streaky part, and since it adheres to the adherend by point contact or line contact, it has adhesive properties to the adherend. It may be inferior. Further, in the conventional pressure-sensitive adhesive sheet, even when the surface of the pressure-sensitive adhesive layer is processed by the sandblasting method, the region of the uneven convex portion formed on the exposed surface of the pressure-sensitive adhesive layer is surrounded by a circle having a diameter of 100 μm. It is difficult to have a flat surface having a selectable area in the area, and the adhesive property to the adherend may be inferior because it adheres to the adherend by point contact.

The flat surface existing on the surface of the pressure-sensitive adhesive layer, which has irregularities due to the transfer of an embossed pattern having a predetermined shape due to a general design, has a constant size, shape, etc., or flat surfaces having substantially the same shape overlap. It exists, and it is difficult to improve various properties selected from adhesive properties, appearance, punching workability, etc. in a well-balanced manner.

<Requirements (Iii)>
As shown in FIG. 2, the pressure-sensitive adhesive sheet of the present invention has a flat surface having an irregular shape. A fixed flat surface may exist on the surface (α) of the resin layer. The amorphous flat surface existing on the surface (α) of the resin layer is a flat surface having an area in which a region surrounded by a circle with a diameter of 100 μm can be selected by observation from the surface (α) side of the resin layer. It may be a flat surface other than that. Whether or not the shape of the flat surface is irregular is determined by visually observing the surface (α) of the resin layer from the surface (α) side of the resin layer or observing it with a digital microscope (magnification: 30 to 100 times). Specifically, it means the result evaluated by the method described in the examples.
However, in one aspect of the present invention, as shown in FIG. 2, it is preferable that one or more amorphous flat surfaces 14 are present on the surface (α) 12a of the resin layer 12, and the amorphous flat surfaces are preferably present. It is preferable that a plurality of 14 are present.
Since the irregular concave portion is present on the surface (α) of the resin layer, it is possible to obtain a pressure-sensitive adhesive sheet having a well-balanced air bleeding property and adhesive properties.

<Specific requirements for a flat surface existing on the surface (α)>
In one aspect of the present invention, the flat surface existing on the surface (α) and satisfying the requirements (Ii) and (Iii) further meets any one or more of the following requirements (I-1) to (I-3). It is preferable that it is satisfied.
· Requirements (I-1): the surface of the resin layer (alpha) 0.2 mm ² or more on (preferably 0.3 mm ² or more, more preferably 0.4 mm ² or more) flat surface with an area of (f2) is There is one or more.
Further, one or more flat surfaces (S) excluding the flat surface having a cumulative relative frequency of 30% or less, which is obtained by adding the relative frequency from the smaller area of each flat surface among the plurality of flat surfaces. It is preferable that the following requirements (I-2) and / or (I-3) are satisfied in the area (D) including the flat surface (S).
-Requirement (I-2): The skewness Sk value for the normal distribution curve of the area and frequency of each of one or more flat surfaces (S) is 1.0 or more.
-Requirement (I-3): The kurtosis Ku value for the normal distribution curve of the area and frequency of each of one or more flat surfaces (S) is 1.8 or more.

Further, any of the requirements (I-1) to (I-3) is applied to the surface (α) of the resin layer or an arbitrarily selected area (D) of 8 mm in length × 10 mm in width on the surface (α). It suffices if there is a flat surface that satisfies the requirements, and it is more preferable that there is a flat surface that satisfies a plurality of requirements (I-1) to (I-3) in an overlapping manner.
By satisfying any one of the requirements (I-1) to (I-3), it is possible to obtain an adhesive sheet having various characteristics such as air bleeding and adhesive characteristics improved in a well-balanced manner.

<Requirements (I-1)>
In one aspect of the present invention, one flat surface (f2) having an area of ^{0.2 mm 2} or more (preferably 0.3 mm ² or more, more preferably 0.4 mm ² or more) is formed on the surface (α) of the resin layer. It is preferable that there are more than one, and it is more preferable that there are a plurality of the flat surfaces (f2).
Since the presence of the flat surface (f2) on the surface (α) provides a sufficient adhesive portion with the adherend on the surface (α), the adhesion with the adherend can be improved, and more. It can be an adhesive sheet with high adhesive strength.
Further, in the above aspect of the present invention, it is preferable that one or more flat surfaces (f2) are present in an arbitrarily selected region (D) of 8 mm in length × 10 mm in width on the surface (α) of the resin layer. It is more preferable that a plurality of the flat surfaces (f2) are present.
In the above aspect, it is not necessary that all the flat surfaces existing on the surface (α) or region (D) of the resin layer correspond to the flat surface (f2), and the surface (α) or region (α) or region ( The flat surface existing in D) may include the flat surface (f2).

Further, both the above-mentioned flat surface (f1) and (f2) are applicable to the surface (α) or the arbitrarily selected area (D) of 8 mm in length × 10 mm in width on the surface (α) or the surface (α) of the resin layer. It is preferable that one or more surfaces (f12) are present, and it is more preferable that a plurality of the flat surfaces (f12) are present.

In the present invention, it is determined whether or not the above-mentioned flat surfaces (f1), (f2), and (f12) are present on the surface (α) or the region (D) of the resin layer of the target pressure-sensitive adhesive sheet. An image obtained by observing a flat surface existing on the surface (α) or region (D) of the above using a digital microscope (magnification: 30 to 100 times) is obtained, and based on the image, an image analysis software is used. It may be determined whether or not a region surrounded by a circle with a diameter of 100 μm can be selected, and the area of a flat surface may be calculated.

<Flat surface (S)>
The "flat surface (S)" existing on the surface (α) of the resin layer is the cumulative relative frequency obtained by adding the relative frequency from the smaller area of each flat surface among the plurality of flat surfaces existing in the region (D). Refers to the remaining flat surface excluding the flat surface of 30% or less.

In the present invention, "a flat surface having a cumulative relative frequency of 30% or less, which is obtained by adding the relative frequency from the smaller area of each flat surface" is excluded for the following reasons.
That is, when an image of a region (D) of 8 mm in length × 10 mm in width arbitrarily selected by a digital microscope is acquired, the flat surface approaching the end of the region (D) is the boundary line of the region (D). It may be cut off by the four sides of a rectangle. This "cut flat surface" varies depending on how the region (D) is selected, and is not a flat surface that actually exists on the surface (α).
In this way, when the influence of the data of the cut flat surface that does not actually exist, including the flat surface cut by the four sides of the rectangle that is the boundary line of the region (D), becomes large, it is different from the actual situation. There is concern that it will become data.
By the way, most of the "flat surfaces cut by the rectangle that is the boundary line of the region (D)" are "flat surfaces having a cumulative relative frequency of 30% or less, which is obtained by adding the relative frequencies from the smaller area of each flat surface". included.
Therefore, in the present invention, instead of examining the standard deviation, skewness, and kurtosis of the flat surface existing in the region (D), the area of each flat surface is small from the flat surface existing in the region (D). The standard deviation, skewness, and kurtosis of the "flat surface (S)" excluding the "flat surface with a cumulative relative frequency of 30% or less, which is the sum of the relative frequencies," are calculated, so that they actually exist. The effect of the "flat surface cut by the rectangle, which is the boundary line of the region (D)", on the standard deviation, skewness, and kurtosis values is adjusted to be small.

<Requirements (I-2)>
In one aspect of the present invention, the pressure-sensitive adhesive sheet has a plurality of flat surfaces in an arbitrarily selected region (D) of 8 mm in length × 10 mm in width on the surface (α), and the area of the plurality of flat surfaces exists. The skewness Sk value for the normal distribution curve of each area and frequency of one or more flat surfaces (S) excluding the flat surface having a cumulative relative frequency of 30% or less, which is the sum of the smaller ones, is 1 or more. Is preferable.
In the present invention, the "skewness Sk value" defined in the requirement (I-2) is statistically the asymmetry of the normal distribution curve when the area and frequency of the flat surface (S) are normally distributed. Represents the degree.
When the skewness Sk value = 0, the distribution curve of the area and frequency of the flat surface (S) has a symmetrical shape.
If the skewness Sk value> 0 (the skewness Sk value is a positive value), the distribution curve of the area and frequency of the flat surface (S) has a shape in which the peak is biased to the left and the tail of the distribution curve extends to the right. It becomes.
If the skewness Sk value <0 (the skewness Sk value is a negative value), the distribution curve of the area and frequency of the flat surface (S) has a shape in which the peak is biased to the right and the tail of the distribution curve extends to the left. It becomes.
Further, it is shown that the larger the absolute value of the skewness Sk value, the larger the skewness.

In the requirement (I-2), the distribution curve of the area and frequency of the flat surface (S) existing on the surface (α) is smaller than the average value of the area of the flat surface (S). It is distorted toward the higher frequency, and stipulates that the area of the flat surface (S) has a wide distribution.
It is considered that such a distribution is caused by the existence of a flat surface (S) having a small area around the flat surface (S) having a large area. It is considered that the adhesive strength can be improved on a large flat surface, while the air bleeding property can be ensured by the recesses adjacent to the small flat surface around the large flat surface.
In one aspect of the invention, as indicated by the skewness Sk value specified in Requirement (I-2), a small area around a large area flat surface (S) present on the surface (α) of the pressure-sensitive adhesive layer. Due to the distribution such that the flat surface (S) is present, the contact between the adhesive layer and the adherend surface varies appropriately, and various characteristics such as air bleeding property, adhesive property, appearance, and punching process are exhibited. The adhesive sheet can be improved in a well-balanced manner.

In one aspect of the present invention, the "skewness Sk value" specified in the requirement (I-2) is preferably 1.0 or more, more preferably 1.1 or more, still more preferably 1.2 or more. , More preferably 1.3 or more.

It should be noted that a plurality of convex surfaces are present on the surface of the pressure-sensitive adhesive layer having irregularities formed by using a release material having an embossed pattern having a predetermined shape according to a general design. A plurality of flat surfaces (convex surfaces) formed by using a release material having an embossed pattern existing on the surface of the pressure-sensitive adhesive layer are largely due to the design of the embossed pattern, but are large because the formation of the embossed pattern is complicated. In many cases, the shape and the like are constant, or flat surfaces having substantially the same shape exist in an overlapping manner, and the shape has a certain regularity.
When a plurality of flat surfaces formed by using a release agent having an embossed pattern are present on the surface of the pressure-sensitive adhesive layer, the shape of the flat surfaces often has regularity, and thus the above requirement (I-2). The specified skewness Sk value rarely exceeds 1.0.

In the present invention, the skewness Sk value for the normal distribution curve of the area and frequency of each of one or more flat surfaces (S) is based on the following formula (2), and graph software (Microsoft Japan Co., Ltd., Excel) is used. Can be calculated.

〔式（２）中、ｎは平坦面（Ｓ）の個数、ｘ_ｉは、各平坦面（Ｓ）の各々の面積（ｉ：１，２，・・・ｎ）、μは各平坦面（Ｓ）の面積の平均値、ｓは標本標準偏差を示す。〕

[In the formula (2), n is the number of flat surfaces (S), x _i is the area of each flat surface (S) (i: 1, 2, ... n), and μ is each flat surface ( S) is the average value of the area, and s is the sample standard deviation. ]

<Requirements (I-3)>
In one aspect of the present invention, the pressure-sensitive adhesive sheet has a plurality of flat surfaces in an arbitrarily selected region (D) of 8 mm in length × 10 mm in width on the surface (α), and the area of the plurality of flat surfaces exists. Kurtosis Ku value for the normal distribution curve of each area and frequency of one or more flat surfaces (S) excluding flat surfaces with cumulative relative frequency of 30% or less, which is the sum of the smaller ones, is 1.8 or more. It is preferable to have.
In the present invention, the "kurtosis Ku value" defined in the requirement (I-3) statistically represents the degree to which the peak of the distribution and the tail curve of the distribution curve are different from the normal distribution curve.
When the kurtosis Ku value = 0, the shape of the distribution curve almost completely matches the normal distribution curve.
If the kurtosis Ku value> 0 (the kurtosis Ku value is a positive value), the distribution curve has a sharper peak than the normal distribution curve, and the distribution curve has a heavy tail, that is, the tail of the distribution curve. Shows an expansive shape.
If the kurtosis Ku value <0 (the kurtosis Ku value is a negative value), the distribution curve has a flat peak compared to the normal distribution, and the distribution curve has a light tail, that is, the tail of the distribution curve. Shows a shape with a small spread.

In the requirement (I-3), the distribution curve of the area and frequency of the flat surface (S) existing on the surface (α) has a sharper peak than the normal distribution curve, and the tail of the distribution curve is widened. It stipulates that.
The skewness Sk value of the area of the flat surface (S) is 1.0 or more, and the kurtosis Ku value is 1.8 or more, which means that the distribution curve of the area and frequency of the flat surface (S) is determined. It means that the shape is different from the normal distribution while having a numerical bias toward the smaller one.
That is, the distribution of the flat surface (S) existing on the surface (α) ensures a sufficient numerical ratio of the flat surface (S) having a small area, while also minimizing the flat surface (S) having a large area. If it is more than the ratio, it will be the distribution that existed. Therefore, the contact between the pressure-sensitive adhesive layer and the adherend surface varies appropriately, and the pressure-sensitive adhesive sheet can be obtained with various characteristics such as air bleeding property, adhesive properties, appearance, and punching process improved in a well-balanced manner.

In one aspect of the present invention, the "kurtosis Ku value" defined in the requirement (I-3) is preferably 0.5 or more, more preferably 1.0 or more, more preferably 1.5 or more, and more preferably. Is 1.8 or more, more preferably 1.9 or more, still more preferably 2.0 or more, still more preferably 2.1 or more.

When a plurality of flat surfaces (convex surfaces) formed by using a release material having an embossed pattern having a predetermined shape by a general design are present on the surface of the pressure-sensitive adhesive layer, the shape of the flat surface has regularity. In many cases. Therefore, the kurtosis Ku value specified in the above requirement (I-3) rarely exceeds 1.8.

In the present invention, the kurtosis value for the normal distribution curve of the area and frequency of each of one or more flat surfaces (S) is determined by using graph software (Microsoft Japan Co., Ltd., Excel) based on the following formula (3). Can be calculated.

〔式（３）中、ｎは平坦面（Ｓ）の個数、ｘ_ｉは各平坦面（Ｓ）の各々の面積（ｉ：１，２，・・・ｎ）、μは各平坦面（Ｓ）の面積の平均値、ｓは標本標準偏差を示す。〕

[In the formula (3), n is the number of flat surfaces (S), x _i is the area of each flat surface (S) (i: 1, 2, ... n), and μ is each flat surface (S). ) Indicates the average value, and s indicates the sample standard deviation. ]

<Requirements for recesses observed from the surface (α) side>
In one aspect of the present invention, it is preferable that a plurality of recesses existing on the surface (α) and having an irregular shape when observed from the surface (α) side are present on the surface (α), and further, the following requirements. It is preferable that (I-4) is satisfied.
Requirement (I-4): 70 in a region (D) of 8 mm in length × 10 mm in width arbitrarily selected on the surface (α) with respect to 100% of the total area of the recesses existing in the region (D). It is preferred that there are recesses having an area of ~ 99.99% (more preferably 85-99.99%).

By satisfying the requirement (I-4), it is possible to obtain an adhesive sheet having various characteristics such as air bleeding and adhesive characteristics improved in a well-balanced manner.

Further, in the present invention, in the region (D) of 8 mm in length × 10 mm in width arbitrarily selected on the surface (α) specified in the requirement (I-4), the total area of the recesses existing in the region (D). The ratio of the area of one recess to 100% indicates the continuity of one recess. In one aspect of the present invention, in the arbitrarily selected region (D) of the surface (α) of the resin layer of the resin sheet, at least one of the recesses existing in the region (D) is the region (D). It is preferable that the recesses existing inside are continuous at a ratio of 70 to 99.99% with respect to the total area of 100%, and the recesses having such continuity can improve the air bleeding property.

For the above "area ratio occupied by the recess", an image of the surface (α) is acquired using a digital microscope (magnification: 30 to 100 times), and the image is image-processed (binarized). Can be calculated. Further, 1 to 10 areas (D) arbitrarily selected on the surface (α) having a length of 8 mm and a width of 10 mm are selected, and an image of the area is obtained using a digital microscope (magnification: 30 to 100 times). Obtained, calculate the value of "area ratio occupied by concave or flat surface" of each region from the image, and calculate the average of the values of the selected regions 1 to 10 on the surface (α) of the resin layer of the target pressure-sensitive adhesive sheet. ) Can also be regarded as the "area ratio occupied by the concave or flat surface".

In one aspect of the present invention, from the viewpoint of continuity of the recesses, the recesses existing on the surface (α) of the resin layer are preferably different from those due to the transfer of the embossed pattern. Depending on the design of the embossed pattern, it is also possible that there are irregularities with one continuous recess. In the present invention, the recesses are not due to the transfer of the embossed pattern, so that one continuous recess does not exist, in other words, in an arbitrarily selected area (D) on the surface (α). It is preferable that there is no one or more recesses having an area of 100% with respect to the total area of the recesses existing in the region (D).

In the present invention, the "area of the recess" is obtained by acquiring an image of the surface (α) using a digital microscope (magnification: 30 to 100 times) and performing image processing (binarization processing) on the image. Can be measured by automatic area measurement. The area ratio of the maximum recess to the total area of the recess in the region (D) surrounded by a rectangle of 8 mm in length × 10 mm in width arbitrarily selected on the surface (α) of the resin layer can be calculated based on the following formula.
Area ratio of maximum recess to total area of recess = [Area of maximum recess] / [Total area of recess] x 100

In one aspect of the present invention, it is preferable that one or more irregularly shaped recesses are present in a region (Q) surrounded by an arbitrarily selected square having a side of 1 mm on the surface (α) of the resin layer. It is more preferable that there are a plurality of irregularly shaped recesses.
By having one or more irregularly shaped recesses in the above-mentioned region (Q), it is possible to obtain an adhesive sheet having various characteristics such as air bleeding property and adhesive characteristics improved in a well-balanced manner.

In one aspect of the present invention, the recess 13 existing on the surface (α) 12a of the resin layer 12 preferably has a maximum height difference of 0.5 μm or more.
The "recess" defined here refers to a recess having a maximum height difference of 0.5 μm or more, and it is sufficient that a portion having a height difference of 0.5 μm or more exists 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.

FIG. 3 is a schematic cross-sectional view of the resin layer showing an example of the shape of the resin layer on the surface (α) side of the pressure-sensitive adhesive sheet of the present invention.
Like the recess 13 shown in FIG. 3A, the shape of the normal recess has two peaks (M ₁ ) and (M ₂ ) and a valley portion (N). In the present invention, the "maximum height difference" of the recess is _{the highest position (m) of the two mountain portions (M 1} ) and (M ₂ ) with respect to the thickness direction of the resin layer 12 (FIG. 3 (a). ) Means the length of the difference (h) between the peak portion ( _{maximum point of M 1} ) and the lowest position (n) (minimum point of the valley portion (N) in FIG. 3 (a)).
Further, in the case of FIG. 3 (b), _{a recess 131 having two mountain portions (M 11} ) and (M ₁₂ ) and a valley portion (N ₁ ), and two mountain portions (M ₁₂ ). It is considered to have two recesses, (M ₁₃ ) and a recess 132 having a valley portion (N _2). In this case, the length of the difference (h ₁ ) between the maximum point of the mountain portion (M _{11 ) and the minimum point of the valley portion (N 1} ) represents the maximum height difference of the recess 131, and the maximum of the mountain portion (M ₁₃ ). _{The length of the difference (h 2} ) between the point and the minimum point of the valley portion (N ₂ ) represents the maximum height difference of the recess 132.

The maximum height difference of one recess is more preferably 1.0 μm or more from the viewpoint of improving the air bleeding property of the pressure-sensitive adhesive sheet, maintaining a good appearance of the pressure-sensitive adhesive sheet, and the shape stability of the pressure-sensitive adhesive sheet. It is not less than or equal to the thickness of the resin layer, more preferably 3.0 μm or more and not more than the thickness of the resin layer, and even more preferably 5.0 μm or more and not more than the thickness of the resin layer.

The average value of the widths of the recesses is preferably 1 to 500 μm, more preferably 3 to 400 μm, and more preferably 3 to 400 μm, from the viewpoint of improving the air bleeding property of the adhesive sheet and improving the adhesiveness of the adhesive sheet. It is preferably 5 to 300 μm.
In the present invention, the width of the recess means the distance between the maximum points of the two peaks, and in the recess 13 shown in FIG. 3 (a), the peak (M ₁ ) and the peak. Refers to the distance L from (M _2). Further, in the concave portion 131 shown in FIG. 3 (b) refers to the distance _{L 1} between the peak portions _{(M 11)} and the peak portions _{(M 12),} in the recess 132, the peak portions _{(M 13)} and the mountain Refers to the distance L ₂ from the portion (M _12).
Further, when the adhesive sheet of the present invention is viewed in a plan view (when viewed from directly above), when the concave portion has a long side and a short side, the short side is referred to as a width.

As the ratio of the maximum height difference of the one recess to the average value of the width [maximum height difference / average value of the width] (in the recess 13 shown in FIG. 3A, it means "h / L"). Is preferably 1/500 to 100/1, more preferably 3/400 to 70/3, still more preferably, from the viewpoint of improving the air bleeding property of the adhesive sheet and improving the adhesiveness of the adhesive sheet. It is 1/60 to 10/1.

In one aspect of the present invention, from the viewpoint of forming an adhesive sheet in which a plurality of recesses and flat portions satisfying the above requirements (Ii) and (Iii) are present, a recess that further satisfies the requirement (I-4) is preferable. From the viewpoint of forming an adhesive sheet in which the above-mentioned is present, it is preferable that the recess is not formed by using a release material having an embossed pattern.
The "recess formed by using the release material having an embossed pattern" includes, for example, the following, and is distinguished from the recess of the above aspect.
-A recess formed by transferring an embossed pattern by pressing a release sheet having an embossed pattern against the flat surface of the adhesive layer formed from the adhesive composition.
-Using a peeling sheet having an embossed pattern on the peeling surface, the pressure-sensitive adhesive composition is applied to the peeling surface to form a pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive layer is removed. Recessed surface exposed on the surface of.
Such recesses cause a number of problems as listed as problems with the pressure-sensitive adhesive sheet described in Patent Document 1 described above.

In one aspect of the present invention, the recess is formed by self-forming the resin layer from the viewpoint of forming an adhesive sheet in which a recess and a flat surface satisfying the above requirements are formed on the surface (α) of the resin layer. Is preferable.
In the present invention, "self-forming" means a phenomenon that naturally creates a disordered shape in the process of autonomous formation of a resin layer, and more specifically, it is formed from a composition which is a material for forming the resin layer. It means a phenomenon that naturally creates a disordered shape in the process of autonomous formation of a resin layer by drying the coating film.
The shape of the recess formed by the self-formation of the resin layer can be adjusted to some extent by adjusting the drying conditions and the type and content of the components in the composition which is the material for forming the resin layer. Although it is possible, unlike the groove formed by the transfer of the embossed pattern, it can be said that "it is virtually impossible to reproduce the exact same shape". Therefore, it can be said that the recess formed by the self-formation of the resin layer is irregular.
Further, the shape of the flat surface becomes irregular due to the formation of the irregular concave portion.

The process of forming the recess formed by the self-formation of the resin layer is considered as follows.
First, at the time of forming a coating film made of a composition as a material for forming a resin layer, a shrinkage stress is generated inside the coating film in the step of drying the coating film, and the bonding force of the resin is weakened. , Cracks occur in the coating film. Then, it is considered that the resin around the cracked portion flows into the space temporarily created by the crack to form a recess on the surface (α) of the resin layer.
By forming two layers of coating film having different resin contents and then drying the two layers of coating film at the same time, a shrinkage stress difference is generated inside the coating film during drying, and the coating film is cracked. It will be easier.

From the viewpoint of facilitating the formation of recesses, it is preferable to make adjustments in consideration of the following items as appropriate. It is considered that the factors due to these matters act in combination to facilitate the formation of recesses. Incidentally, a preferred embodiment of each item for facilitating the formation of the concave portion is as described in the corresponding item described later.
-Type, constituent monomer, molecular weight, and content of the resin contained in the composition that is the material for forming the coating film.
-The type of cross-linking agent and the type of solvent contained in the composition that is the material for forming the coating film.
-Viscosity and solid content concentration of the composition that forms the coating film.
-Thickness of the coating film to be formed. (In the case of multiple layers, the thickness of each coating film)
-Drying temperature and drying time of the formed coating film.

In the formation of the pressure-sensitive adhesive layer of a general pressure-sensitive adhesive sheet, the above items are often set as appropriate for the purpose of forming the pressure-sensitive adhesive layer having a flat surface.
On the other hand, in the present invention, the above items are set so as to intentionally form a recess that can contribute to the improvement of the air bleeding property of the pressure-sensitive adhesive sheet. Is completely different.

It is preferable that the above items are appropriately set in consideration of the fluidity of the resin contained in the formed coating film and the like.
For example, when the composition contains fine particles, the viscosity of the coating film composed of the composition containing a large amount of fine particles is adjusted to an appropriate range to maintain the predetermined fluidity of the fine particles in the coating film. Mixing with other coating films (coating films containing a large amount of resin) can be appropriately suppressed. By adjusting in this way, in the coating film containing a large amount of resin, cracks occur in the horizontal direction, and recesses tend to be easily formed.
As a result, the proportion of the recesses formed on the surface (α) can be increased, and the proportion of the recesses connected to each other can also be increased to obtain an adhesive sheet having better air bleeding property.

Further, among the above items, it is preferable to appropriately adjust the type, constituent monomer, molecular weight, and resin content of the resin so that the resin contained in the coating film containing a large amount of resin has appropriate viscoelasticity.
That is, by appropriately increasing the hardness of the coating film (hardness determined by factors such as the viscoelasticity of the resin and the viscosity of the coating liquid), the shrinkage stress of the resin portion (X) becomes stronger, and recesses are likely to be formed. Become. The harder the coating film, the stronger the shrinkage stress and the more likely it is that recesses will occur, but if it is too hard, the coating suitability will decrease. Further, if the elasticity of the resin is increased too much, the adhesive strength of the resin layer formed from the coating film tends to decrease. In consideration of this point, it is preferable to appropriately adjust the viscoelasticity of the resin.
In addition, when fine particles are contained in the composition or coating film, by optimizing the dispersed state of the fine particles, the degree of swelling of the thickness of the resin layer due to the fine particles and the self-forming force of the recesses can be adjusted, resulting in the result. It is considered that a recess can be easily formed on the surface (α) and can be adjusted.

Further, it is preferable to appropriately set the above items in consideration of the crosslinking rate of the formed coating film (or the composition which is the forming material).
That is, if the cross-linking speed of the coating film is too fast, the coating film may be cured before the recesses are formed. It also affects the size of cracks and the size of recesses in the coating film.
The cross-linking rate of the coating film can be adjusted by appropriately setting the type of the cross-linking agent and the type of the solvent in the composition as the forming material, and the drying time and the drying temperature of the coating film.

When the resin layer is a layer containing a resin portion (X) containing a resin and a particle portion (Y) composed of fine particles, the resin layer formed by the above-mentioned self-formation is shown in FIG. 1 (a). As shown in (d), the particle portion (Y) has a distribution in which the proportion of the particle portion (Y) is smaller than that in the portion where the recess is present on the surface (α). Tend.
This is because, in the process of self-formation of the resin layer, when the recess is formed on the surface (α) of the resin layer, the fine particles existing at the position where the recess is formed move. It is considered to have become a distribution.

Hereinafter, each configuration of the pressure-sensitive adhesive sheet of the present invention will be described.
〔Base material〕
The base material used in one aspect of the present invention is not particularly limited, and examples thereof include a paper base material, a resin film or a sheet, a base material obtained by laminating a paper base material with a resin, and the like. It can be appropriately selected according to the use of the sheet.
Examples of the paper constituting the paper base material include thin leaf paper, medium-quality paper, high-quality paper, impregnated paper, coated paper, art paper, sulfate paper, glassin paper and the like.
Examples of the resin constituting the resin film or sheet include polyolefin resins such as polyethylene and polypropylene; vinyl such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer. Resins; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; polyurethane, acrylic modified polyurethane and other urethane resins; polymethylpentene; Examples thereof include polysulfone; polyether ether ketone; polyether sulfone; polyphenylene sulfide; polyimide resin such as polyetherimide and polyimide; polyamide resin; acrylic resin; fluororesin and the like.
Examples of the base material obtained by laminating the paper base material with a resin include laminated paper obtained by laminating the above-mentioned paper base material with a thermoplastic resin such as polyethylene.

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.
When the pressure-sensitive adhesive sheet of the present invention is used for applications requiring heat resistance, a film or sheet composed of a resin selected from polyethylene naphthalate and a polyimide-based resin is preferable, and applications requiring weather resistance. When used in, a film or sheet composed of a resin selected from polyvinyl chloride, polyvinylidene chloride, acrylic resin, and fluororesin is preferable.

The thickness of the base material is appropriately set according to the use of the pressure-sensitive adhesive sheet of the present invention, but is preferably 5 to 1000 μm, more preferably 10 to 500 μm, and even more preferably 12 to 12 to 1000 μm, more preferably 10 to 500 μm, from the viewpoint of handleability and economy. It is 250 μm, more preferably 15 to 150 μm.
The substrate may further contain various additives such as an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, and a colorant.

Further, the base material used in one aspect of the present invention is preferably a non-breathable base material from the viewpoint of improving the blister resistance of the obtained pressure-sensitive adhesive sheet, and specifically, the surface of the above-mentioned resin film or sheet. A substrate having a metal layer on top is preferred.
Examples of the metal contained in the metal layer include metals having a metallic luster such as aluminum, tin, chromium, and titanium.
As a method for forming the metal layer, for example, a method of vapor-depositing the metal by a PVD method such as vacuum vapor deposition, sputtering, ion plating, or a metal foil made of the metal is attached using a general pressure-sensitive adhesive. Although a method and the like can be mentioned, a method of depositing the above metal by the PVD method is preferable.

Further, when a resin film or sheet is used as the base material, the surface of the resin film or sheet is subjected to an oxidation method or unevenness from the viewpoint of improving the adhesion to the resin layer laminated on the resin film or sheet. Surface treatment by a method or the like, or primer treatment may be performed.
Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone, and ultraviolet irradiation treatment, and examples of the unevenness method include a sandblast method and a solvent treatment method. And so on.

[Release material]
As the release material used in one aspect of the present invention, a release sheet that has been subjected to double-sided release treatment, a release sheet that has been subjected to single-sided release treatment, or the like, and a release agent coated on a substrate for the release material, or the like is used. Can be mentioned.
It should be noted that the peeling surface is preferably a peeling material that is flat and has no uneven shape (for example, a peeling material that is not embossed).
Examples of the base material for the release material include the above-mentioned paper base material used as the base material of the pressure-sensitive adhesive sheet of one aspect of the present invention, a resin film or sheet, and a base material obtained by laminating a paper base material with a resin. Be done.
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.
The thickness of the release material is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 170 μm, and even more preferably 35 to 80 μm.

[Resin layer]
As shown in FIG. 1, the resin layer 12 of the pressure-sensitive adhesive sheet of the present invention preferably contains a resin portion (X) containing a resin and a particle portion (Y) composed of fine particles.
The resin portion (X) indicates a portion containing a component other than the fine particles contained in the resin layer. That is, not only the resin but also the components other than the fine particles such as the tackifier, the cross-linking agent, and the general-purpose additive contained in the resin layer are contained in the "resin portion (X)".
On the other hand, the particle portion (Y) indicates a portion made of fine particles contained in the resin layer.

By including the particle portion (Y) in the resin layer, the shape retention after sticking can be improved, and the generation of blister is effectively suppressed when the obtained adhesive sheet is used at high temperature. be able to.
The distribution of the resin portion (X) and the particle portion (Y) in the resin layer 12 may be such that the resin portion (X) and the particle portion (Y) are substantially evenly distributed, and may be locally distributed. The configuration may be such that a portion mainly composed of a resin portion (X) and a portion mainly composed of a particle portion (Y) can be separated.

The resin layer of the pressure-sensitive adhesive sheet according to one aspect of the present invention preferably has a void portion (Z) in addition to the resin portion (X) and the particle portion (Y). By having the void portion (Z) in the resin layer, the blister resistance of the pressure-sensitive adhesive sheet can be improved.
The void portion (Z) also includes voids existing between the fine particles and, when the fine particles are secondary particles, voids existing in the secondary particles.
When the resin layer has a multi-layer structure, the resin portion (X) flows into the void portion (Z) even if the void portion (Z) is present in the process of forming the resin layer or immediately after the formation. In some cases, the voids disappear and the resin layer has no void portion (Z).
However, even when the void portion (Z) that has temporarily existed in the resin layer disappears in this way, the pressure-sensitive adhesive sheet according to one aspect of the present invention has recesses on the surface (α) of the resin layer. Therefore, the air bleeding property is good, and since the resin layer has the particle portion (Y), the blister resistance is also excellent.

Further, the shear storage elastic modulus of the resin layer of the pressure-sensitive adhesive sheet of one aspect of the present invention at 100 ° C. is preferably 9.0 × 10 ³ Pa or more from the viewpoint of improving the air bleeding property and blister resistance of the pressure-sensitive adhesive sheet. , More preferably 1.0 × 10 ⁴ Pa or more, still more preferably 2.0 × 10 ⁴ Pa or more.
In the present invention, the shear storage elastic modulus of the resin layer at 100 ° C. is measured by measuring at a frequency of 1 Hz using a viscoelasticity measuring device (for example, manufactured by Rheometrics, device name “DYNAMIC ANALYZER RDA II”). Means the value that was set.

The total thickness of the resin layer is preferably 1 to 300 μm, more preferably 5 to 150 μm, and even more preferably 10 to 75 μm.

In the pressure-sensitive adhesive sheet of the present invention, at least the surface (α) of the resin layer on the side opposite to the side on which the base material or the release material is provided has adhesiveness, but the base material or the release material is provided. The surface (β) of the resin layer on the side may also have adhesiveness.

The adhesive strength on the surface (α) of the resin layer of the pressure-sensitive adhesive sheet according to the present invention is preferably 0.5 N / 25 mm or more, more preferably 2.0 N / 25 mm or more, and more preferably 3.0 N / 25 mm or more. It is more preferably 4.0 N / 25 mm or more, and even more preferably 7.0 N / 25 mm or more.
When the surface (β) of the resin layer also has adhesiveness, the adhesive force on the surface (β) preferably belongs to the above range.
The value of the adhesive strength of the adhesive sheet means the value measured by the method described in the examples.

<Multi-layer structure of resin layer>
The resin layer may be a multilayer structure composed of two or more types of layers.
The resin layer having such a multi-layer structure includes a layer (Xβ) mainly containing a resin portion (X) from the side where the base material or the release material is provided, such as the pressure-sensitive adhesive sheet 1a in FIG. Examples thereof include a layer (Y1) containing 15% by mass or more of a particle portion (Y) and a multilayer structure in which a layer (Xα) mainly containing a resin portion (X) is laminated in this order.
In the configuration of the multi-layer structure of the resin layer, the boundary between the two layers to be laminated cannot be discriminated, and the layers may be in a mixed state.
That is, in the resin layer 12 of the pressure-sensitive adhesive sheet 1a of FIG. 1, the boundary between the layer (Xβ) and the layer (Y1) and / or the boundary between the layer (Y1) and the layer (Xα) cannot be discriminated. , May be a mixed structure.

Hereinafter, the structure of the resin layer as a multilayer structure will be described by taking as an example the resin layer 12 composed of the three layers of the layer (Xβ), the layer (Y1), and the layer (Xα) of the pressure-sensitive adhesive sheet 1a of FIG. explain.

The layer (Xβ) and the layer (Xα) are layers mainly containing the resin portion (X), but may include the particle portion (Y). However, the content of the particle portion (Y) in the layer (Xβ) and the layer (Xα) is independently 15% by mass with respect to the total mass (100% by mass) of the layer (Xβ) or the layer (Xα). % And less than the content of the resin in the layer (Xβ) or layer (Xα).
That is, the layer (Xβ) and the layer (Xα) are distinguished from the layer (Y1) in terms of the content of the particle portion (Y).
The layer (Xβ) and the layer (Xα) may further have the above-mentioned void portion (Z) in addition to the resin portion (X) and the particle portion (Y).

The content of the resin portion (X) in the layer (Xβ) and the layer (Xα) is usually 85 mass with respect to the total mass (100% by mass) of the layer (Xβ) or the layer (Xα) independently. It is more than%, preferably 87 to 100% by mass, more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass, still more preferably 100% by mass.
The above-mentioned "content of the resin portion (X)" is a resin, a tackifier, a cross-linking agent, and a general-purpose addition constituting the resin portion (X) contained in the layer (Xβ) or the layer (Xα). It means the total content of components other than fine particles such as agents.

The content of the fine particles constituting the particle portion (Y) in the layer (Xβ) and the layer (Xα) is independently based on the total mass (100% by mass) of the layer (Xβ) or the layer (Xα). , But preferably 0 to 13% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, still more preferably 0% by mass.
In the present invention, the "content of fine particles in the layer (Xβ) and the layer (Xα)" is the total amount (100% by mass) of the resin composition which is the material for forming the layer (Xβ) or the layer (Xα). However, it can also be regarded as the content of fine particles in))).

The content of the resin in the layer (Xα) is usually 30 to 100% by mass, preferably 40 to 100% by mass, and more preferably 50 to 100% with respect to the total mass (100% by mass) of the layer (Xα). It is by mass, more preferably 60 to 100% by mass.
On the other hand, the content of the resin in the layer (Xβ) is usually 50 to 100% by mass, preferably 65 to 100% by mass, and more preferably 75 with respect to the total mass (100% by mass) of the layer (Xβ). It is ~ 100% by mass, more preferably 85 to 100% by mass.
In the present invention, the "content of the resin in the layer (Xβ) and the layer (Xα)" is the total amount (100% by mass) of the resin composition which is the material for forming the layer (Xβ) or the layer (Xα). However, it can be regarded as the content of the resin in))).

The layer (Y1) may be a layer composed of only a particle portion (Y), a layer including a resin portion (X) together with the particle portion (Y), and a layer having a void portion (Z). May be.
The content of the fine particles constituting the particle portion (Y) in the layer (Y1) is 15% by mass or more, preferably 20 to 100% by mass, based on the total mass (100% by mass) of the layer (Y1). It is by mass, more preferably 25 to 90% by mass, still more preferably 30 to 85% by mass, and even more preferably 35 to 80% by mass.

The content of the resin in the layer (Y1) is usually 0 to 85% by mass, preferably 1 to 80% by mass, and more preferably 5 to 75% with respect to the total mass (100% by mass) of the layer (Y1). It is by mass, more preferably 10 to 70% by mass, and even more preferably 20 to 65% by mass.

In the present invention, "the content of fine particles in the layer (Y1)" and "the content of the resin in the layer (Y1)" are the total amount (100 mass) of the composition which is the material for forming the layer (Y1). It can also be regarded as the content of fine particles or resin in% (excluding the diluting solvent).

In one aspect of the present invention, the layer (Xα) is preferably a layer formed from a composition (xα) containing a resin and having a fine particle content of less than 15% by mass.
Similarly, the layer (Xβ) is also preferably a layer formed from the composition (xβ) containing a resin and having a fine particle content of less than 15% by mass.
Further, the layer (Y1) is preferably a layer formed of the composition (y) containing 15% by mass or more of fine particles.
The preferred embodiments (contents, content, etc.) of the composition (xα), the composition (xβ), and the composition (y1) are as described below.

<Resin part (X)>
The resin portion (X) constituting the resin layer is a portion containing components other than the fine particles contained in the resin layer, and is distinguished from the particle portion (Y) in that respect.
The resin portion (X) may contain a tackifier, a cross-linking agent, a general-purpose additive, and the like together with the resin.

The content of the resin in the resin portion (X) is usually 30% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, based on the total amount (100% by mass) of the resin portion (X). It is more preferably 55% by mass or more, further preferably 60% by mass or more, still more preferably 70% by mass or more, and preferably 100% by mass or less, more preferably 99.9% by mass or less.
In the present invention, the value of the content of the resin in the resin composition used as the material for forming the resin portion (X) can also be regarded as the above-mentioned "content of the resin in the resin portion (X)".

The resin contained in the resin portion (X) preferably contains an adhesive resin from the viewpoint of developing adhesiveness on the surface (α) of the formed resin layer.
In particular, as in the pressure-sensitive adhesive sheet 1a of FIG. 1A, the resin layer is the layer (Xβ), the layer (Y1), and the layer (Xα) in this order from the side where the base material or the release material is provided. In the case of having a multilayer structure laminated with the above, it is preferable that at least the layer (Xα) contains an adhesive resin from the above viewpoint.
Further, from the viewpoint of forming the double-sided pressure-sensitive adhesive sheet and improving the adhesion to the base material, it is preferable that at least the layer (Xα) and the layer (Xβ) contain the pressure-sensitive adhesive resin.

Examples of the adhesive resin include acrylic resin, urethane resin, rubber resin, silicone resin and the like.
Among these adhesive resins, it is preferable to contain an acrylic resin from the viewpoint of having good adhesive properties and weather resistance and facilitating the formation of recesses on the surface (α) of the resin layer.
The content of the acrylic resin is preferably 25 to 100% by mass, more preferably 50 to 100% by mass, and further preferably 70 with respect to the total amount (100% by mass) of the resin contained in the resin portion (X). It is ~ 100% by mass, more preferably 80 to 100% by mass, and even more preferably 100% by mass.

Further, from the viewpoint of facilitating the formation of recesses on the surface (α) of the resin layer, the resin portion (X) preferably contains a resin having a functional group, and more preferably contains an acrylic resin having a functional group. ..
In particular, as in the pressure-sensitive adhesive sheet 1a of FIG. 1A, the resin layer is the layer (Xβ), the layer (Y1), and the layer (Xα) in this order from the side where the base material or the release material is provided. In the case of the multilayer structure laminated with the above, it is preferable that at least the layer (Y1) contains a resin having a functional group from the above viewpoint.
The functional group is a group that serves as a starting point for cross-linking with a cross-linking agent, and examples thereof include a hydroxy group, a carboxy group, an epoxy group, an amino group, a cyano group, a keto group, an alkoxysilyl group, and the like, but the carboxy group is used. preferable.

The resin portion (X) preferably further contains a cross-linking agent together with the resin having the functional group. In particular, when the resin layer is the above-mentioned multilayer structure, it is preferable that at least the layer (Y1) contains a cross-linking agent together with the resin having the functional group.
Examples of the cross-linking agent include an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an aziridine-based cross-linking agent, a metal chelate-based cross-linking agent, and the like.

The isocyanate-based cross-linking agent is, for example, aromatic polyisocyanate such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate; aliphatic polyisocyanate such as hexamethylene diisocyanate; alicyclic polyisocyanate such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; In addition, an adduct compound which is a reaction product of these compounds with a biuret compound, an isocyanate compound, and a low molecular weight active hydrogen-containing compound (ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc.); etc. Can be mentioned.

Examples of the epoxy-based cross-linking agent include ethylene glycol glycidyl ether, 1,3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N, N, N', N'-tetraglycidyl-m-xylylenediamine, and the like. Examples thereof include 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, and diglycidyl amine.

Examples of the aziridine-based cross-linking agent include diphenylmethane-4,4'-bis (1-aziridinecarboxamide), trimethylolpropanetri-β-aziridinylpropionate, and trimethylolmethanetri-β-aziridinyl. Propionate, toluene-2,4-bis (1-aziridinecarboxamide), trimethylolpropane, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) phosphine, Examples thereof include trimethylolpropane tri-β- (2-methylaziridine) propionate.

Examples of the metal chelate-based cross-linking agent include chelate compounds in which the metal atom is aluminum, zirconium, titanium, zinc, iron, tin, etc., but from the viewpoint of facilitating the formation of recesses on the surface (α) of the resin layer, aluminum Chelate-based cross-linking agents are preferred.
Examples of the aluminum chelate cross-linking agent include diisopropoxyaluminum monooleylacetate, monoisopropoxyaluminum bisoleylacetate, monoisopropoxyaluminum monooleate monoethylacetate, diisopropoxyaluminum monolaurylacetate, and diisopropoxyaluminum monooleylacetate. Examples thereof include isopropoxyaluminum monostearyl acetoacetate and diisopropoxyaluminum monoisostearyl acetoacetate.

These cross-linking agents may be used alone or in combination of two or more.
Among these, from the viewpoint of facilitating the formation of recesses on the surface (α) of the resin layer, it is preferable that the resin portion (X) contains at least one selected from a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent. It is more preferable to contain a metal chelate-based cross-linking agent, and further preferably to contain an aluminum chelate-based cross-linking agent.

The content of the cross-linking agent in the resin portion (X) is preferably 0.01 to 15 parts by mass, more preferably 0.1 with respect to 100 parts by mass of the functional group-containing resin contained in the resin portion (X). It is 10 parts by mass, more preferably 0.3 to 7.0 parts by mass.

Further, as one aspect of the present invention, it is preferable that the resin portion (X) contains both a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent from the viewpoint of facilitating the formation of recesses on the surface (α) of the resin layer. ..
When the resin portion (X) contains both the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent, from the above viewpoint, the content ratio of the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent in the resin portion (X) [metal chelate-based cross-linking agent]. The cross-linking agent / epoxy-based cross-linking agent] is preferably 10/90 to 99.5 / 0.5, more preferably 50/50 to 99.0 / 1.0, and even more preferably 65/35 in terms of mass ratio. It is ~ 98.5 / 1.5, more preferably 75/25 ~ 98.0 / 2.0.

From the viewpoint of further improving the adhesive properties of the surface (α), the resin portion (X) preferably further contains an adhesive-imparting agent together with the adhesive resin. In particular, when the resin layer is the above-mentioned multi-layer structure, it is preferable that the layer (Xα) contains a tacky resin and a tackifier.

The tackifier used in the present invention is a component that supplementarily improves the adhesive strength of the adhesive resin, and refers to an oligomer having a mass average molecular weight (Mw) of usually less than 10,000, and is the same as the above-mentioned adhesive resin. Is distinct.
The mass average molecular weight (Mw) of the tackifier is preferably 400 to 8000, more preferably 5000 to 5000, and more preferably 800 to 3500.

Examples of the tackifier include rosin-based resins such as rosin resin, rosin ester resin, and rosin-modified phenol resin; hydride-based resin obtained by hydrogenating these rosin-based resins; terpene resin, aromatic-modified terpene resin, and terpene phenol. Terpen-based resins such as terpene-based resins; Hydrogenated terpene-based resins obtained by hydrogenating these terpene-based resins; Styrene obtained by copolymerizing a styrene-based monomer such as α-methylstyrene or β-methylstyrene with an aliphatic monomer. Styrene-based resin; Hydrolyzed styrene-based resin obtained by hydrogenating these styrene-based resins; C5-based resin obtained by copolymerizing C5 distillates such as penten, isoprene, piperin, and 1.3-pentadiene produced by thermal decomposition of petroleum naphtha. Styrene petroleum resin of petroleum resin and this C5 series petroleum resin; C9 series petroleum resin obtained by copolymerizing C9 distillates such as inden and vinyltoluene produced by thermal decomposition of petroleum naphtha and this C9 series petroleum resin are hydrogenated. Styrene resin; etc.
The tackifier used in the present invention may be used alone or in combination of two or more having different softening points and structures.

The softening point of the tackifier is preferably 80 ° C. or higher, more preferably 80 to 180 ° C., still more preferably 83 to 170 ° C., and even more preferably 85 to 150 ° C.
In the present invention, the "softening point" of the tackifier means a value measured according to JIS K 2531.
Further, when two or more kinds of a plurality of tackifiers are used, it is preferable that the weighted average of the softening points of the plurality of tackifiers belongs to the above range.

When the tackifier is contained in the resin portion (X), the content of the tackifier is preferably 1 part by mass or more with respect to 100 parts by mass of the tacky resin contained in the resin portion (X). It is preferably 1 to 200 parts by mass, more preferably 3 to 150 parts by mass, and even more preferably 5 to 90 parts by mass.

Further, the resin portion (X) may contain a general-purpose additive other than the above-mentioned cross-linking agent and tackifier.
Examples of general-purpose additives include antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators, ultraviolet absorbers and the like.
These general-purpose additives may be used alone or in combination of two or more.
When these general-purpose additives are contained, the content of each general-purpose additive is preferably 0.0001 to 60 parts by mass, more preferably 0.001 to 50 parts by mass with respect to 100 parts by mass of the resin. ..

The resin contained in the resin portion (X) may be used alone or in combination of two or more.
The material for forming the resin portion (X) of the resin layer of the pressure-sensitive adhesive sheet of the present invention is preferably a pressure-sensitive adhesive containing a pressure-sensitive adhesive resin having a functional group, and an acrylic resin (A) having a functional group (hereinafter referred to as). , It is more preferable that it is an acrylic pressure-sensitive adhesive containing (also referred to simply as "acrylic resin (A)"), and it is an acrylic pressure-sensitive adhesive containing an acrylic resin (A) having a functional group and a cross-linking agent (B). Is even more preferable.
The acrylic pressure-sensitive adhesive may be either a solvent type or an emulsion type.
Hereinafter, the above-mentioned acrylic pressure-sensitive adhesive, which is suitable for using the resin portion (X) as a forming material, will be described.

The acrylic resin (A) contained in the acrylic pressure-sensitive adhesive has, for example, a polymer having a structural unit derived from an alkyl (meth) acrylate having a linear or branched alkyl group, and a cyclic structure ( Examples thereof include polymers having a structural unit derived from meta) acrylate.
The mass average molecular weight (Mw) of the acrylic resin (A) is preferably 50,000 to 1.5 million, more preferably 150,000 to 1.3 million, still more preferably 250,000 to 1.1 million, and even more preferably 350,000 to 90. It is 10,000.

The acrylic resin (A) is a structural unit (a1) derived from an alkyl (meth) acrylate (a1') having an alkyl group having 1 to 18 carbon atoms (hereinafter, also referred to as “monomer (a1 ′)”). And an acrylic copolymer (A1) having a structural unit (a2) derived from a functional group-containing monomer (a2') (hereinafter, also referred to as “monomer (a2 ′)”), and preferably contains an acrylic copolymer (A1). It is more preferable that it is a coalescence (A1).
The content of the acrylic copolymer (A1) is preferably 50 to 100% by mass, more preferably 70 to 100% by mass, based on the total amount (100% by mass) of the acrylic resin (A) in the acrylic pressure-sensitive adhesive. It is by mass, more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass.
The form of the copolymerization of the acrylic copolymer (A1) is not particularly limited, and may be any of a block copolymer, a random copolymer, and a graft copolymer.

The number of carbon atoms of the alkyl group contained in the monomer (a1') is more preferably 4 to 12, still more preferably 4 to 8, and even more preferably 4 to 6 from the viewpoint of improving the adhesive properties.
Examples of the monomer (a1') include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and tridecyl (). Examples thereof include meta) acrylate and stearyl (meth) acrylate.
Among these, butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are preferable, and butyl (meth) acrylate is more preferable.

The content of the structural unit (a1) is preferably 50 to 99.5% by mass, more preferably 60 to 99% by mass, based on the total structural unit (100% by mass) of the acrylic copolymer (A1). It is more preferably 70 to 95% by mass, and even more preferably 80 to 93% by mass.

Examples of the monomer (a2') include a hydroxy group-containing monomer, a carboxy group-containing monomer, an epoxy group-containing monomer, an amino group-containing monomer, a cyano group-containing monomer, a keto group-containing monomer, and an alkoxysilyl group-containing monomer. ..
Among these, a carboxy group-containing monomer is more preferable.
Examples of the carboxy group-containing monomer include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid and the like, and (meth) acrylic acid is preferable.

The content of the structural unit (a2) is preferably 0.5 to 50% by mass, more preferably 1 to 40% by mass, based on the total structural unit (100% by mass) of the acrylic copolymer (A1). It is more preferably 5 to 30% by mass, and even more preferably 7 to 20% by mass.

The acrylic copolymer (A1) may have a structural unit (a3) derived from other monomers (a3') other than the above-mentioned monomers (a1') and (a2').
Examples of the other monomer (a3') include cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyl. Examples thereof include (meth) acrylate having a cyclic structure such as oxyethyl (meth) acrylate and imide (meth) acrylate, vinyl acetate, acrylonitrile, and styrene.

The content of the structural unit (a3) is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, still more preferably, with respect to the total structural unit (100% by mass) of the acrylic copolymer (A1). Is 0 to 10% by mass, more preferably 0 to 5% by mass.
The above-mentioned monomers (a1') to (a3') may be used alone or in combination of two or more.

The method for synthesizing the acrylic copolymer (A1) component is not particularly limited, and for example, the raw material monomer is dissolved in a solvent and solution-polymerized in the presence of a polymerization initiator, a chain transfer agent, or the like. It is produced by a method or a method of emulsion polymerization in an aqueous system using a raw material monomer in the presence of an emulsifier, a polymerization initiator, a chain transfer agent, a dispersant and the like.

Examples of the cross-linking agent (B) contained in the acrylic pressure-sensitive adhesive include the above-mentioned ones, but from the viewpoint of improving the pressure-sensitive adhesive properties and from the viewpoint of facilitating the formation of recesses on the surface (α) of the resin layer. Therefore, it is preferable to contain one or more selected from the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent, more preferably to contain the metal chelate-based cross-linking agent, and further preferably to contain the aluminum chelate-based cross-linking agent.
Further, as one aspect of the present invention, from the viewpoint of improving the shape retention of the plurality of recesses existing on the surface (α) of the resin layer, the cross-linking agent (B) includes a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent. It is preferable to include the agent together.

The content of the cross-linking agent (B) is preferably 0.01 to 15 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the acrylic resin (A) in the acrylic pressure-sensitive adhesive. , More preferably 0.3 to 7.0 parts by mass.

When a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent are used in combination, the content ratio of the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent [metal chelate-based cross-linking agent / epoxy-based cross-linking agent] is preferably a mass ratio. 10/90 to 99.5 / 0.5, more preferably 50/50 to 99.0 / 1.0, even more preferably 65/35 to 98.5 / 1.5, even more preferably 75/25 to It is 98.0 / 2.0.

The acrylic pressure-sensitive adhesive used in one aspect of the present invention may contain a general-purpose additive as long as the effects of the present invention are not impaired. Examples of the general-purpose additive include those described above, and the content of the general-purpose additive is also as described above.

Further, the acrylic pressure-sensitive adhesive used in one aspect of the present invention preferably further contains a pressure-sensitive adhesive from the viewpoint of further improving the pressure-sensitive adhesive properties of the surface (α). Examples of the tackifier include those mentioned above, and the content of the tackifier is also as described above.

The acrylic pressure-sensitive adhesive used in one aspect of the present invention includes adhesive resins other than the acrylic resin (A) (for example, urethane-based resin, rubber-based resin, silicone-based resin, etc., as long as the effects of the present invention are not impaired. ) May be contained.
The content of the acrylic resin (A) in the acrylic pressure-sensitive adhesive is preferably 50 to 100% by mass, more preferably 70, based on the total amount (100% by mass) of the pressure-sensitive adhesive resin contained in the acrylic pressure-sensitive adhesive. It is ~ 100% by mass, more preferably 80 to 100% by mass, and even more preferably 100% by mass.

<Particle part (Y)>
The resin layer of the pressure-sensitive adhesive sheet according to one aspect of the present invention preferably contains a particle portion (Y) composed of fine particles.
The average particle size of the fine particles is preferably 0.01 from the viewpoint of improving the air bleeding property and blister resistance of the pressure-sensitive adhesive sheet and from the viewpoint of facilitating the formation of recesses and flat surfaces on the surface (α) of the resin layer. It is ~ 100 μm, more preferably 0.05 to 25 μm, still more preferably 0.1 to 10 μm.

The fine particles used in one embodiment of the present invention are not particularly limited, and include inorganic particles such as silica particles, metal oxide particles, barium sulfate, calcium carbonate, magnesium carbonate, glass beads, and smectite, and organic particles such as acrylic beads. Can be mentioned.
Among these fine particles, one or more selected from silica particles, metal oxide particles, and smectite are preferable, and silica particles are more preferable.

The silica particles used in one aspect of the present invention may be either dry silica or wet silica.
Further, the silica particles used in one embodiment of the present invention are organically modified silica surface-modified with an organic compound having a reactive functional group, or inorganically modified silica surface-treated with an inorganic compound such as sodium aluminate or sodium hydroxide. , And organic-inorganic modified silica surface-treated with these organic compounds and inorganic compounds, organic-inorganic modified silica surface-treated with an organic-inorganic hybrid material such as a silane coupling agent, and the like may be used.
In addition, these silica particles may be a mixture consisting of two or more kinds.

The mass concentration of silica in the silica particles is preferably 70 to 100% by mass, more preferably 85 to 100% by mass, and further preferably 90 to 100% by mass with respect to the total amount (100% by mass) of the silica particles. ..
Further, the volume average secondary particle diameter of the silica particles used in one embodiment of the present invention has a recess and a flat surface on the surface (α) of the resin layer from the viewpoint of improving the air bleeding property and the blister resistance of the pressure-sensitive adhesive sheet. From the viewpoint of facilitating formation, it is preferably 0.5 to 10 μm, more preferably 1 to 8 μm, and even more preferably 1.5 to 5 μm.
In the present invention, the value of the volume average secondary particle diameter of the silica particles is a value obtained by measuring the particle size distribution by the Coulter counter method using a multisizer / three machine or the like.

Examples of the metal oxide particles include particles made of titanium oxide, alumina, boehmite, chromium oxide, nickel oxide, copper oxide, titanium oxide, zirconium oxide, indium oxide, zinc oxide, and a metal oxide selected from a composite oxide thereof. And the like, and sol particles made of these metals oxide are also included.

Examples of smectite include montmorillonite, bidelite, hectorite, saponite, stibunsite, nontronite, saponite and the like.

The mass retention after heating the resin layer of the pressure-sensitive adhesive sheet according to one aspect of the present invention at 800 ° C. for 30 minutes is preferably 3 to 90% by mass, more preferably 5 to 80% by mass, and further preferably 7 to 70. It is by mass, more preferably 9 to 60% by mass.
The mass retention rate can be regarded as indicating the content (mass%) of the fine particles contained in the resin layer.
When the mass retention rate is 3% by mass or more, it can be an adhesive sheet having excellent air bleeding resistance and blister resistance. Further, during the production of the pressure-sensitive adhesive sheet of the present invention, recesses are likely to be formed on the surface (α) of the resin layer.
On the other hand, when the mass retention rate is 90% by mass or less, the pressure-sensitive adhesive sheet having high film strength of the resin layer and excellent water resistance and chemical resistance can be obtained. Further, during the production of the pressure-sensitive adhesive sheet of the present invention, a flat surface is likely to be formed on the surface (α) of the resin layer.

[Manufacturing method of adhesive sheet]
Next, a method for manufacturing the pressure-sensitive adhesive sheet of the present invention will be described.
The method for producing the pressure-sensitive adhesive sheet of the present invention is not particularly limited, but at least the following steps (1) are taken from the viewpoint of productivity and from the viewpoint of facilitating the formation of recesses and flat surfaces on the surface (α) of the resin layer. And (2) are preferred.
Step (1): A coating film (x') containing a resin and having a fine particle content of less than 15% by mass (x), and a coating film (y) containing 15% by mass or more of fine particles. Step of forming (y') Step (2): Step of simultaneously drying the coating film (x') and the coating film (y') formed in the step (1).

<Process (1)>
The step (1) is a coating film (x') containing a resin and having a fine particle content of less than 15% by mass (x), and a coating film (y) containing 15% by mass or more of fine particles. This is a step of forming a film (y').
The composition (x) is a material for forming the resin portion (X), and preferably contains a cross-linking agent together with the above-mentioned resin, and may further contain a tackifier and the above-mentioned general-purpose additive.
Further, the composition (y) is a material for forming the particle portion (Y), but may further contain a resin, a cross-linking agent, a tackifier, and the above-mentioned general-purpose additive. The composition (y) containing components other than fine particles such as these resins is a material for forming the particle portion (Y) and also a material for forming the resin portion (X).

(Composition (x))
Examples of the resin contained in the composition (x) include the resin constituting the above-mentioned resin portion (X), and an adhesive resin having a functional group is preferable, and an acrylic resin (A) having the above-mentioned functional group is preferable. Is more preferable, and the above-mentioned acrylic copolymer (A1) is further preferable.

The content of the resin in the composition (x) is usually 30% by mass or more, preferably 40% by mass or more, based on the total amount of the composition (x) (100% by mass (excluding the diluting solvent)). It is more preferably 50% by mass or more, more preferably 55% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more, and preferably 100% by mass or less, more preferably 99.9% by mass. By mass or less, more preferably 95% by mass or less.

Examples of the cross-linking agent contained in the composition (x) include the cross-linking agent contained in the resin portion (X) described above, wherein the composition (x) is a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent. It is preferable to contain one or more selected from the agents, and more preferably to contain a metal chelate-based cross-linking agent.
Further, as one aspect of the present invention, from the viewpoint of improving the shape retention of the plurality of recesses existing on the surface (α) of the resin layer, the composition (x) is a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent. It is preferable to include both.
When the composition (x) contains both the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent, the content ratio of the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent in the composition (x) [metal chelate-based cross-linking agent / epoxy The cross-linking agent] is preferably 10/90 to 99.5 / 0.5, more preferably 50/50 to 99.0 / 1.0, and even more preferably 65 / 35-98.5 in terms of mass ratio. /1.5, and even more preferably 75/25 to 98.0 / 2.0.

The content of the cross-linking agent is preferably 0.01 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0, with respect to 100 parts by mass of the resin contained in the composition (x). It is 3 to 7.0 parts by mass.

The composition (x) is preferably an acrylic pressure-sensitive adhesive containing the above-mentioned acrylic resin (A) having a functional group and the cross-linking agent (B), and the above-mentioned acrylic copolymer (A1) and cross-linking. It is more preferable that the acrylic pressure-sensitive adhesive contains the agent (B). Further, the acrylic pressure-sensitive adhesive may further contain a tackifier and a general-purpose additive.
The details of the acrylic pressure-sensitive adhesive are as described above.

The composition (x) may contain the above-mentioned fine particles.
However, the content of the fine particles in the composition (x) is less than 15% by mass, and is smaller than the content of the resin contained in the composition (x).
The content of the fine particles in the specific composition (x) is preferably less than 15% by mass, based on the total amount of the composition (x) (100% by mass (excluding the diluting solvent)). Is 0 to 13% by mass, more preferably 0 to 10% by mass, still more preferably 0 to 5% by mass, still more preferably 0% by mass.

(Composition (y))
The composition (y) is a material for forming the particle portion (Y) and contains at least 15% by mass or more of the above-mentioned fine particles, but from the viewpoint of dispersibility of the fine particles, it is preferable to contain a resin together with the fine particles. It is more preferable to contain a cross-linking agent together with the resin. Further, the composition (y) may further contain a tackifier and a general-purpose additive.
The components (resin, cross-linking agent, tackifier and general-purpose additive) contained in the composition (y) other than the fine particles serve as a material for forming the resin portion (X).

Examples of the fine particles contained in the composition (y) include those described above, but silica particles are formed from the viewpoint of forming a void portion (Z) in the resin layer to form an adhesive sheet having improved blister resistance. , Metal oxide particles, and one or more selected from smectite are preferable.
The content of the fine particles in the composition (y) is a composition from the viewpoint of facilitating the formation of amorphous recesses and flat surfaces formed by the self-formation of the resin layer on the surface (α) of the resin layer. 15% by mass or more, preferably 20 to 100% by mass, more preferably 25 to 90% by mass, still more preferably, based on the total amount of (y) (100% by mass (excluding the diluting solvent)). It is 30 to 85% by mass, more preferably 35 to 80% by mass.

Examples of the resin contained in the composition (y) include the same resins as those contained in the above-mentioned composition (x), and it is preferable to include the same resin as the composition (x). These resins may be used alone or in combination of two or more.
Further, as a more specific resin contained in the composition (y), a resin having a functional group is preferable, an acrylic resin (A) having the above-mentioned functional group is more preferable, and the above-mentioned acrylic copolymer is more preferable. (A1) is more preferable.

The content of the resin in the composition (y) is usually 0 to 85% by mass, preferably 1 to 80% by mass, based on the total amount of the composition (y) (100% by mass (excluding the diluting solvent)). %, More preferably 5 to 75% by mass, still more preferably 10 to 70% by mass, still more preferably 20 to 65% by mass.

Examples of the cross-linking agent contained in the composition (y) include the same cross-linking agents contained in the resin portion (X) described above. Among these, the composition (y) preferably contains one or more selected from a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent, and more preferably contains a metal chelate-based cross-linking agent. Further, as one aspect of the present invention, it is preferable that the composition (y) contains both a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent.
When the composition (y) contains both the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent, a suitable content ratio (mass ratio) of the metal chelate-based cross-linking agent and the epoxy-based cross-linking agent in the composition (y). The range of is the same as that of the composition (x) described above.

The content of the cross-linking agent in the composition (y) is preferably 0.01 to 15 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the resin contained in the composition (y). Parts, more preferably 0.3 to 7.0 parts by mass.

(Method for forming coating film (x') and (y'))
When forming the coating film, it is preferable to add a solvent to the compositions (x) and (y) in the form of a solution of the composition in order to facilitate the formation of the coating film.
Examples of such a solvent include water, an organic solvent and the like.
Examples of the organic solvent include toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, t-butanol, s-butanol, acetylacetone, cyclohexanone, n-hexane, cyclohexane and the like. .. In addition, these solvents may be used alone or in combination of 2 or more.

The order in which the coating films (x') and (y') formed in this step are laminated is not particularly limited, but the coating film (x') is formed so as to be laminated on the coating film (y'). Is preferable.
As a method for forming the coating film (x') and (y'), a method of forming the coating film (y') and then sequentially forming the coating film (x') on the coating film (y') may be used. Further, from the viewpoint of productivity, a method of simultaneously coating the coating film (y') and the coating film (x') with a multilayer coater may be used.
Examples of the coater used for sequential formation include a spin coater, a spray coater, a bar coater, a knife coater, a roll coater, a knife roll coater, a blade coater, a gravure coater, a curtain coater, and a die coater.
Examples of the coater used for simultaneous coating with the multilayer coater include a curtain coater and a die coater. Among these, a die coater is preferable from the viewpoint of operability.

In this step (1), after the formation of at least one of the coating film (x') and the coating film (y') and before moving to the step (2), the pre-curing reaction of the coating film does not proceed. It may be dried.
The drying temperature at the time of performing the pre-drying treatment in this step (1) is usually set appropriately in a temperature range to the extent that the formed coating film does not cure, but is preferably set in the step (2). Is less than the drying temperature of. The specific drying temperature indicated by the definition of "less than the drying temperature in step (2)" is preferably 10 to 45 ° C, more preferably 10 to 34 ° C, and even more preferably 15 to 30 ° C.

<Process (2)>
The step (2) is a step of simultaneously drying the coating film (x') and the coating film (y') formed in the step (1).
By simultaneously drying the formed coating film (x') and coating film (y') in this step, a resin layer containing a resin portion (X) and a particle portion (Y) is formed, and the coating film (y') is formed. A plurality of recesses and flat surfaces are formed on the surface (α) of the resin layer.

The drying temperature in this step is preferably 35 to 200 ° C., more preferably 60 to 180 ° C., still more preferably 70 to 160 ° C. from the viewpoint of facilitating the formation of recesses and flat surfaces on the surface (α) of the resin layer. , More preferably 80 to 140 ° C.
When the drying temperature is 35 ° C. or higher, an adhesive sheet having good air bleeding property can be obtained. On the other hand, when the drying temperature is 200 ° C. or lower, it is possible to suppress problems such as shrinkage of the base material and the release material of the pressure-sensitive adhesive sheet.
The lower the drying temperature, the larger the height difference of the formed recesses, but the number of the formed recesses tends to decrease.

The void portion (Z) is likely to be formed around the particle portion (Y) of the resin layer formed by this step.
The void portion (Z) can be easily formed by using one or more selected from silica particles, metal oxide particles, and smectite as the fine particles contained in the composition (y) described above.

Further, like the pressure-sensitive adhesive sheet 1a of FIG. 1A, a layer (Xβ) mainly containing a resin portion (X), a layer (Y1) containing 15% by mass or more of a particle portion (Y), and mainly a resin. When producing a pressure-sensitive adhesive sheet having a resin layer formed by laminating layers (Xα) including portions (X) in this order to form a multilayer structure, the production methods of the first and second embodiments shown below. Is preferable.

In the description of the production method of the first and second aspects below, the "composition (xβ)" and the "composition (xα)" are the same as the above-mentioned composition (x) unless otherwise specified. Details of each component (resin, cross-linking agent, tackifier, general-purpose additive, diluting solvent, etc.) contained in the composition (xβ) or (xα) (specific example of each component, suitable component). , Component content, solid content concentration, etc.) are also the same as the above-mentioned composition (x). The "composition (y)" is also as described above.

[Manufacturing method of the first aspect]
The production method of the first aspect has at least the following steps (1A) and (2A).
Step (1A): A coating film (xβ') comprising a composition (xβ) containing a resin and having a fine particle content of less than 15% by mass on a substrate or a release material, and a composition containing 15% by mass or more of the fine particles. A coating film (y') composed of a substance (y) and a coating film (xα') composed of a composition (xα) containing a resin and having a fine particle content of less than 15% by mass are laminated and formed in this order. Step Step (2A): Step of simultaneously drying the coating film (xβ'), the coating film (y'), and the coating film (xα') formed in the step (1A).

Also in the step (1A), it is preferable to add the above-mentioned solvent to the composition (xβ), the composition (y), and the composition (xα) to form a solution of the composition, and then apply the mixture. ..
As a method for forming the coating film (xβ'), the coating film (y'), and the coating film (xα'), after forming the coating film (xβ') on the substrate or the release material, the coating film (xβ') is formed. A method of sequentially forming a coating film (y') on the coating film (y') and then forming a coating film (xα') on the coating film (y') using the above-mentioned coater may be used. A method of simultaneously applying and forming the film (xβ'), the coating film (y') and the coating film (xα') using the above-mentioned multilayer coater may also be used.

In this step (1A), after forming one or more coating films of the coating film (xβ'), the coating film (y'), and the coating film (xα'), before moving to the step (2A). Pre-drying treatment may be performed so that the curing reaction of the coating film does not proceed.
For example, after each coating film of the coating film (xβ'), the coating film (y'), and the coating film (xα') is formed, the above pre-drying treatment may be performed each time, and the coating film (xβ') may be performed. ) And the coating film (y'), the above-mentioned pre-drying treatment may be performed collectively, and then the coating film (xα') may be formed.
The drying temperature at the time of performing the pre-drying treatment in this step (1A) is usually set appropriately in a temperature range to the extent that the formed coating film does not cure, but is preferably set in the step (2A). Is less than the drying temperature of. The specific drying temperature indicated by the definition of "less than the drying temperature in step (2A)" is preferably 10 to 45 ° C, more preferably 10 to 34 ° C, and even more preferably 15 to 30 ° C.

The step (2A) is a step of simultaneously drying the coating film (xβ'), the coating film (y'), and the coating film (xα') formed in the step (1A), and the drying temperature in this step is suitable. The range is the same as the above-mentioned step (2). By this step, a resin layer including a resin portion (X) and a particle portion (Y) is formed.

[Manufacturing method of the second aspect]
The production method of the second aspect has at least the following steps (1B) and (2B).
Step (1B): A coating film (y) comprising a composition (y) containing 15% by mass or more of the fine particles on a layer (Xβ) mainly containing a resin portion (X) provided on a base material or a release material. Step of laminating a coating film (xα') composed of a composition (xα) containing y') and a resin as a main component in this order Step (2B): A coating film (y) formed in the step (1B). ') And the step of drying the coating film (xα') at the same time

In the step (1B), the "layer (Xβ) mainly containing the resin portion (X)" is formed by drying a coating film (xβ') composed of the composition (xβ) containing the resin as the main component described above. be able to.
Since the layer (Xβ) is formed from the composition (xβ), the layer (Xβ) may contain a cross-linking agent, a general-purpose additive, or the like in addition to the resin. The content of the resin portion (X) in the layer (Xβ) is as described above.

As a method for forming the layer (Xβ), a coating film (xβ') composed of a composition (xβ') containing a resin as a main component is formed on a base material or a release material, and the coating film (xβ') is dried. Can be formed.
The drying temperature at this time is not particularly limited, and is preferably 35 to 200 ° C, more preferably 60 to 180 ° C, still more preferably 70 to 160 ° C, and even more preferably 80 to 140 ° C.

In this embodiment, the coating film (y') and the coating film (xα') are formed in this order not on the coating film (xβ') but on the layer (Xβ) obtained after drying. , Different from the first aspect described above.
Also in the step (1B), it is preferable to add the above-mentioned solvent to the composition (y) and the composition (xα) to form a solution of the composition, and then apply the mixture.
As a method for forming the coating film (y') and the coating film (xα'), after forming the coating film (y') on the layer (Xβ), the coating film (xα') is formed on the coating film (y'). ) May be formed sequentially using the above-mentioned coater, or the coating film (y') and the coating film (xα') may be simultaneously applied and formed using the above-mentioned multilayer coater. good.

In this step (1B), after the coating film (y') is formed, or after the coating film (y') and the coating film (xα') are formed, before moving to the step (2B), the coating film of the coating film is used. Pre-drying treatment may be performed to the extent that the curing reaction does not proceed.
The drying temperature at the time of performing the pre-drying treatment in this step (1B) is usually set appropriately in a temperature range to the extent that curing of the formed coating film does not proceed, but is preferably set in step (2B). Is less than the drying temperature of. The specific drying temperature indicated by the definition of "less than the drying temperature in step (2B)" is preferably 10 to 45 ° C, more preferably 10 to 34 ° C, and even more preferably 15 to 30 ° C.

The step (2B) is a step of simultaneously drying the coating film (y') and the coating film (xα') formed in the step (1B), and the preferable range of the drying temperature in this step is the above-mentioned step (2). ) Is the same. By this step, a resin layer including a resin portion (X) and a particle portion (Y) is formed.

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 production examples and examples are values measured by the following methods.

<Mass average molecular weight (Mw) of resin>
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""TSK gel G1000HXL" (all manufactured by Tosoh Corporation) are connected in sequence.-Column temperature: 40 ° C.
・ Developing solvent: Tetrahydrofuran ・ Flow rate: 1.0 mL / min

<Measurement of volume average secondary particle size of silica particles>
The volume average secondary particle size of the silica particles was determined by measuring the particle size distribution by the Coulter counter method using a multisizer three machine (manufactured by Beckman Coulter).

<Measurement of resin layer thickness>
The measurement was performed using a constant pressure thickness measuring instrument manufactured by Teclock Co., Ltd. (model number: "PG-02J", standard: JIS K6783, Z1702, Z1709 compliant).
Specifically, after measuring the total thickness of the pressure-sensitive adhesive sheet to be measured, the value obtained by subtracting the thickness of the base material or the release sheet measured in advance was defined as the "resin layer thickness".

Production example x-1 to x-4
(Preparation of solutions (xβ-1) to (xβ-2) and (xα-1) to (xα-2) of the resin composition)
To the solution of the acrylic resin which is the adhesive resin of the type and the solid content shown in Table 1, the cross-linking agent and the tackifier of the type and the blending amount shown in Table 1 were added. Then, it is diluted with the diluting solvent shown in Table 1, and the solutions (xβ-1) to (xβ-2) and (xα-1) to (xα) of the resin composition having the solid content concentration shown in Table 1 are used. -2) were prepared respectively.

The details of each component shown in Table 1 used for preparing the solutions (xβ-1) to (xβ-2) and (xα-1) to (xα-2) of the resin composition are as follows. ..
<Polypoly resin solution>
-Solution (i): contains an acrylic resin (x-i) (an acrylic copolymer having a structural unit derived from a raw material monomer composed of BA / AA = 90/10 (mass%), Mw: 630,000). A mixed solution of toluene and ethyl acetate having a solid content concentration of 34.0% by mass.
-Solution (ii): contains an acrylic resin (x-ii) (an acrylic copolymer having a structural unit derived from a raw material monomer composed of BA / AA = 90/10 (mass%), Mw: 470,000). A mixed solution of toluene and ethyl acetate having a solid content concentration of 37.0% by mass.
-Solution (iii): Acrylic copolymer having a structural unit derived from a raw material monomer composed of an acrylic resin (x-iii) (2EHA / VAc / AA = 75/23/2 (% by mass), Mw: 66. A mixed solution of toluene having a solid content concentration of 37.0% by mass and isopropyl alcohol (IPA) containing 10,000).
-Solution (iv): Acrylic copolymer having a structural unit derived from a raw material monomer composed of an acrylic resin (x-iv) (BA / AA / HEA = 94/3/3 (% by mass), Mw: 100. A solution of ethyl acetate having a solid content concentration of 37.0% by mass containing (1).
The abbreviations of the raw material monomers constituting the above-mentioned acrylic copolymer are as follows.
-BA: n-butyl acrylate-2EHA: 2-ethylhexyl acrylate-AA: acrylic acid-VAc: vinyl acetate-HEA: 2-hydroxyethyl acrylate

<Crosslinking agent>
-Al-based cross-linking agent: Product name "M-5A", manufactured by Soken Chemical Co., Ltd., aluminum chelate-based cross-linking agent, solid content concentration = 4.95% by mass.
-Epoxy-based cross-linking agent: A solution of an epoxy-based cross-linking agent obtained by diluting "TETRAD-C" (product name, manufactured by Mitsubishi Gas Chemical Company, Ltd.) with toluene to obtain a solid content concentration of 5% by mass.

<Adhesive enhancer>
-Rosin ester-based TF: Rosin ester-based polymer, Mw: less than 10,000, softening point: 85 ° C.
-Styrene-based TF: Copolymer of styrene-based monomer and aliphatic monomer, Mw: less than 10,000, softening point: 95 ° C.

<Diluting solvent>
-Mixed solvent (1): A mixed solvent prepared by mixing toluene / isopropyl alcohol (IPA) = 65/35 (mass ratio).
-Mixed solvent (2): A mixed solvent prepared by mixing with ethyl acetate / IPA = 86/14 (mass ratio).

Production example f-1
(Preparation of fine particle dispersion (f-1))
Acrylic copolymer having a structural unit derived from the above-mentioned acrylic resin solution (i) containing the acrylic resin (x-i) (butyl acrylate (BA) and acrylic acid (AA), BA / AA = 90. / 10 (% by mass), Mw: 630,000) and a mixed solution of toluene and ethyl acetate having a solid content concentration of 34.0% by mass) with respect to 100 parts by mass (solid content: 34.0 parts by mass). As fine particles, 51.0 parts by mass (solid content: 51.0 parts by mass) and toluene of silica particles (product name "Nipseal E-200A", manufactured by Toso Silica, volume average secondary particle diameter: 3 μm) are added. Then, the fine particles were dispersed to prepare a fine particle dispersion liquid (f-1) containing an acrylic resin and silica particles and having a solid content concentration of 27% by mass.

Production example f-2
(Preparation of fine particle dispersion (f-2))
BA, an acrylic copolymer having a structural unit derived from the above-mentioned solution (ii) containing the acrylic resin (x-ii) (butyl acrylate (BA) and acrylic acid (AA)) instead of the solution (i). / AA = 90/10 (mass%), Mw: 470,000), a mixed solution of toluene having a solid content concentration of 37.0% by mass and ethyl acetate) 100 parts by mass (solid content: 37.0 parts by mass) On the other hand, as fine particles, 55.5 parts by mass (solid content: 55.5 parts by mass) of silica particles (product name "Nipseal E-200A", manufactured by Toso Silica Co., Ltd., volume average secondary particle diameter: 3 μm) And toluene were added to disperse the fine particles to prepare a fine particle dispersion (f-2) containing an acrylic resin and silica particles and having a solid content concentration of 30% by mass.

Production example y-1 to y-2
(Preparation of coating liquids (y-1) to (y-2) for forming a coating film (y'))
A coating liquid for forming a coating film (y') having a solid content concentration shown in Table 2 by adding a fine particle dispersion liquid of the type and blending amount shown in Table 2, a solution of an acrylic resin, a cross-linking agent, and a diluting solvent. (Y-1) to (y-2) were prepared respectively.

The details of each component shown in Table 2 used for preparing the coating films (y-1) to (y-2) for forming the coating film (y') are as follows.
<Particle dispersion liquid>
Dispersion liquid (f-1): A fine particle dispersion liquid (f-1) having a solid content concentration of 27% by mass, which contains an acrylic resin (xi) and silica particles, prepared in Production Example f-1.
Dispersion liquid (f-2): A fine particle dispersion liquid (f-2) having a solid content concentration of 30% by mass, which contains an acrylic resin (x-ii) and silica particles, prepared in Production Example f-2.
<Polypoly resin solution>
-Solution (i): contains an acrylic resin (x-i) (an acrylic copolymer having a structural unit derived from a raw material monomer composed of BA / AA = 90/10 (mass%), Mw: 630,000). A mixed solution of toluene and ethyl acetate having a solid content concentration of 34.0% by mass.
-Solution (ii): contains an acrylic resin (x-ii) (an acrylic copolymer having a structural unit derived from a raw material monomer composed of BA / AA = 90/10 (mass%), Mw: 470,000). A mixed solution of toluene and ethyl acetate having a solid content concentration of 37.0% by mass.
<Crosslinking agent>
-Al-based cross-linking agent: Product name "M-5A", manufactured by Soken Chemical Co., Ltd., aluminum chelate-based cross-linking agent, solid content concentration = 4.95% by mass.
-Epoxy-based cross-linking agent: A solution of an epoxy-based cross-linking agent obtained by diluting "TETRAD-C" (product name, manufactured by Mitsubishi Gas Chemical Company, Ltd.) with toluene to obtain a solid content concentration of 5% by mass.
<Diluting solvent>
IPA / CHN: A mixed solvent consisting of isopropyl alcohol (IPA) and cyclohexanone (CHN) (IPA / CHN = 95/5 (mass ratio)).

Examples 1-2
(1) Formation of coating film Peeling of a release film (manufactured by Lintec Co., Ltd., product name "SP-PET38131", thickness 38 μm, provided with a silicone-based release agent layer on one side of a PET film), which is the first release material. On the agent layer, as shown in Table 3, the solution (xβ-1) of the resin composition prepared in Production Example x-1 and the coating film (y') for forming a coating film (y') prepared in Production Example y-1. (Y-1) and a solution (xβ-1) of the resin composition prepared in Production Example x-1 for forming a coating film (xα') are applied in this order from the release agent layer to a multilayer die coater (a multilayer die coater (y-1). Width: 250 mm) was applied simultaneously, and the coating film (xβ'), the coating film (y'), and the coating film (xα') were formed in this order at the same time.
The application speed of each solution (coating liquid) for forming the coating film (xβ'), the coating film (y'), and the coating film (xα') and the coating amount of each coating film are shown in Table 3. That's right.

(2) Drying treatment Then, the three layers of the coating film (xβ'), the coating film (y') and the coating film (xα') are simultaneously dried at a drying temperature of 100 ° C. for 2 minutes, and the resin portion (X) is dried. ) And the particle portion (Y), and a resin layer having the thickness shown in Table 3 was formed.
In any of Examples 1 and 2, a plurality of recesses and flat surfaces were visually confirmed on the surface (α) of the formed resin layer.

(3) Preparation of Adhesive Sheet without Substrate and Adhesive Sheet with Substrate On the surface (α) of the formed resin layer, a release film as a second release material (manufactured by Lintec Corporation, product name "SP-PET386040"). A pressure-sensitive adhesive sheet without a base material was prepared by laminating so as to be adhered to the surface of the release agent layer of.
Further, the pressure-sensitive adhesive sheet without a base material, which was similarly produced, was allowed to stand in an environment of 23 ° C. for 1 week, and then the first release material was removed to remove the exposed resin layer surface (β) and the base material. A polyethylene terephthalate (PET) film (manufactured by Toray Industries, Inc., product name "Lumirror T60 # 50", thickness 50 μm) was laminated so as to be bonded to a base-based adhesive sheet.

Examples 3-4
(1) Formation of coating film Table 3 is shown on the surface of a polyethylene terephthalate (PET) film (“FNS Keshi N50”, thickness 50 μm, manufactured by Lintec Co., Ltd.) having an aluminum vapor deposition layer on one side. As shown in Production Example x-2, a solution (xβ-2) of the resin composition prepared in Production Example x-2, a coating film (y') for forming a coating film (y') prepared in Production Example y-2, and a production example. The solution (xα-1) or (xα-2) of the resin composition prepared in x-3 to x-4 is simultaneously applied from the top of the aluminum vapor-deposited layer using a multilayer die coater (width: 250 mm) in this order. Then, the coating film (xβ'), the coating film (y'), and the coating film (xα') were formed at the same time in this order.
The application speed of each solution (coating liquid) for forming the coating film (xβ'), the coating film (y'), and the coating film (xα') and the coating amount of each coating film are shown in Table 3. That's right.

(2) Drying treatment Then, the three layers of the coating film (xβ'), the coating film (y') and the coating film (xα') are simultaneously dried at a drying temperature of 100 ° C. for 2 minutes, and the resin portion (X) is dried. ) And the particle portion (Y), and a resin layer having the thickness shown in Table 3 was formed.
In any of Examples 3 to 4, a plurality of recesses and flat surfaces were visually confirmed on the surface (α) of the formed resin layer.

(3) Preparation of Adhesive Sheet with Substrate A pressure-sensitive adhesive sheet with a substrate was obtained by laminating the release film (manufactured by Lintec Corporation, product name "SP-PET38131") so as to be bonded to the surface of the release agent layer.

Comparative Examples 1 to 4
(1) Preparation of Embossed Release Paper A resin film having a thickness of 25 μm made of low-density polyethylene resin (manufactured by Sumitomo Chemical Co., Ltd., product name “Sumikasen (L705),” melting point 106 °) was formed on one side of high-quality paper. Then, the uneven forming surface of the metal engraving plate is brought into close contact with the surface of the resin film, and in that state, it is inserted between two rotating silicon rubber rollers heated to 115 ° C., and the surface of the resin film is embossed. rice field.
A silicone-based release agent (manufactured by Lintec Corporation, product name "same release agent as SP-PET1031") is applied on the surface of the embossed resin film, and then dried at 100 ° C. for 1 minute to a thickness of 110 μm. An embossed release paper was prepared.
The unevenly formed surface of the metal engraving plate is processed so that concave portions and flat surfaces of each shape are formed on the surface (α) of the resin layer of the pressure-sensitive adhesive sheet produced in Comparative Examples 1 to 4. used.
(2) Preparation of Adhesive Sheet with Substrate A solution (xβ-1) of the resin composition prepared in Production Example x-1 shown in Table 1 on the release agent layer of the embossed release paper prepared in (1) above. Was applied using an applicator and then dried at 100 ° C. for 1 minute to form a resin layer so as to have the application rate and the application amount of each coating film shown in Example 1 of Table 3. Then, a PET film (manufactured by Toray Industries, Inc., product name "Lumilar T60 # 50", thickness 50 μm) was laminated so as to be bonded to the surface (α) of the resin layer to prepare an adhesive sheet with a base material.

Using the base-less pressure-sensitive adhesive sheet or the base-attached pressure-sensitive adhesive sheet produced in Examples and Comparative Examples, the resin layer of the pressure-sensitive adhesive sheet and the characteristics of the pressure-sensitive adhesive sheet were measured or observed by the following methods. These results are shown in Table 4.

(1) Preparation of measurement sample As shown in FIG. 4A, non-alkali glass (product name “Eagle XG”, product name “Eagle XG”, which is an adherend 101 having a smooth surface, in order to eliminate the influence of swelling of the adhesive sheet, etc. (Manufactured by Corning Inc.) and the base material of the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples were attached via double-sided tape.
Then, the release material laminated on the surface (α) of the resin layer of the pressure-sensitive adhesive sheet was removed, and the surface (α) of the resin layer was exposed as a measurement sample.

<Whether the recess and flat surface can be visually confirmed>
-Evaluation item (a): Visually observe the surface (α) of the exposed resin layer of the above measurement sample, and check whether the presence of recesses and flat surfaces on the surface (α) can be visually confirmed. , Evaluated according to the following criteria.
A: The presence of recesses and flat surfaces on the surface (α) can be visually confirmed.
F: The presence of recesses and flat surfaces on the surface (α) cannot be visually confirmed.

(2) Acquisition of an image of the region (D) on the surface (α) The surface (α) of the resin layer exposed in the above measurement sample is subjected to the surface (α) using a digital microscope (magnification 50 times). The above arbitrarily selected ranges adjacent to each other were photographed from the direction A of FIG. 4A, and a plurality of adjacent images were concatenated by the image concatenation function of the digital microscope to obtain a concatenated image.
More specifically, in the shooting, the focus is moved in order from the upper part of the portion visually determined to be a flat surface from the direction A in FIG. 4A, and the portion initially focused is the flat surface. Taken as.
Then, in the acquired connected image, a region (D) surrounded by a rectangle having a length of 8 mm and a width of 10 mm was arbitrarily selected as one region, and this was designated as an “image of the region (D)”.
Further, in the acquired connected image, a region (Q) surrounded by a square having a side of 1 mm was arbitrarily selected as one region, and this was designated as a “region (Q) image”.

The imaging conditions of the digital microscope are as follows.
(measuring equipment)
Made by KEYENCE CORPORATION, product name "Digital Microscope VHX-5000", high resolution zoom lens VHX-ZST 100x (measurement conditions)
・ Illumination: ON
・ Stage transmission lighting: OFF
・ Lighting change: Coaxial epi-illumination ・ Edge enhancement: OFF

<Evaluation of the shape of recesses and flat surfaces>
From the "image of the area (D)" acquired in (2) above, the following evaluation items (b1) to (b4) and (c1) to (c4) were observed, and evaluation was performed according to the respective criteria.
The results of these evaluations are shown in Table 4.

(Evaluation items regarding the shape and position of the flat surface existing in the region (D))
-Evaluation item (b1): Observe the "image of the region (D)" acquired in (2) above, observe the presence or absence of recesses and a plurality of irregular flat surfaces, and evaluate according to the following criteria. gone. The results of the evaluation are shown in Table 4.
A: In the region (D), the presence of recesses and a plurality of irregular flat surfaces was confirmed.
B: In the region (D), the presence of recesses and a plurality of flat surfaces was confirmed, but all the confirmed flat surfaces were fixed, and the existence of irregular flat surfaces could not be confirmed.
C: In the region (D), the presence of recesses and irregular flat surfaces could not be confirmed.

In the above evaluation item (b1), the following evaluation items (b2) to (b4) and (c1) to (c4) were observed, and evaluation was performed according to each standard. The results of these evaluations are shown in Table 4.

(Evaluation items regarding the shape and position of the flat surface existing in the region (D))
-Evaluation item (b2): Whether or not there is a flat surface having a size capable of selecting a region surrounded by a circle having a diameter of 100 μm or more in the region (D) was evaluated according to the following criteria.
A +: In the region (D), there is a flat surface having a size that allows selection of a region surrounded by a circle having a diameter of 200 μm.
A: In the region (D), there is a flat surface having a size that allows selection of a region surrounded by a circle having a diameter of 150 μm.
B: In the region (D), there is a flat surface having a size that allows selection of a region surrounded by a circle having a diameter of 100 μm.
C: There is no flat surface in the region (D) having a size that allows the region surrounded by a circle with a diameter of 100 μm to be selected.

-Evaluation item (b3): Whether or not the position where a plurality of flat surfaces of the region (D) exist has periodicity was evaluated according to the following criteria.
A: The position where a plurality of flat surfaces exist does not have periodicity.
F: The position where the plurality of flat surfaces exist has periodicity, or the region (D) does not have the plurality of flat surfaces.

-Evaluation item (b4): Whether or not the shape of the flat surface existing in the region (D) has a shape that becomes a constant repeating unit was evaluated according to the following criteria.
A: The shape of the flat surface does not have a shape that becomes a constant repeating unit.
F: The shape of the flat surface has a shape such that it becomes a constant repeating unit.

(Evaluation items regarding the shape and position of the recesses existing in the area (D))
-Evaluation item (c1): Whether or not there is an amorphous recess in the region (D) was evaluated according to the following criteria.
A: There are a plurality of amorphous recesses.
B: There is only one amorphous recess.
C: There are no irregular recesses.

-Evaluation item (c2): Whether or not a plurality of recesses exist in the region (D) and the positions where the plurality of recesses exist has periodicity was evaluated according to the following criteria.
A: The position where a plurality of recesses exist does not have periodicity.
F: The position where the plurality of recesses are present has periodicity, or the region (D) does not have the plurality of recesses.

-Evaluation item (c3): Whether or not the shape of the concave portion existing in the region (D) has a shape that becomes a constant repeating unit was evaluated according to the following criteria.
A: The shape of the concave portion does not have a shape that becomes a constant repeating unit.
F: The concave portion has a shape such that it becomes a constant repeating unit.

(Evaluation item regarding the presence or absence of amorphous recesses in the area (Q))
-Evaluation item (c4): From the acquired "image of the region (Q)", whether or not an irregular concave portion exists in the region (Q) was evaluated according to the following criteria.
A: There are a plurality of amorphous recesses in the region (Q).
B: There is only one amorphous recess in the region (Q).
C: There is no irregular recess in the region (Q).

(3) Measurement of the area of the recess and the flat surface existing in the area (D) Based on the "image of the area (D)" acquired in the above (2), automatic area measurement is performed using the same digital microscope as above. This was performed to obtain the areas of each recess and each flat surface existing in the region (D).
In the automatic area measurement, the flat surface and the concave portion existing in the region (D) are binarized by a digital microscope and, if necessary, visual image processing, and then the numerical value of the binarized image obtained ( Area) was measured, and the area of each recess and each flat surface was measured. When there were a plurality of recesses and flat surfaces, the areas of each recess and flat surface were measured.
If it is not possible to visually determine whether the surface is a flat surface, the squeegee should not apply a load to the translucent adherend having a smooth surface on the surface (α) of the resin layer as much as possible. The interface between the smooth surface 100a of the translucent adherend 100 and the surface (α) 12a of the resin layer 12 was photographed from the W direction of FIG. 4B, and the pasted portion was a flat surface. I decided that.
As the translucent adherend 100 having a smooth surface 100a, non-alkali glass (product name "Eagle XG", manufactured by Corning Inc.) was used in the same manner as the "adhesion having a smooth surface".
From the obtained data on the area of each recess and the area of each flat surface, various measured values (average value, standard deviation, maximum value, minimum value, etc.) can be obtained using graph software (Microsoft Japan, Excel). Calculated.
The conditions for automatic area measurement are as follows.
(Automatic area measurement conditions)
-Extraction mode: Brightness (weak noise removal)
And extracting region: numerical specification extracting a rectangular longitudinal 8 mm × horizontal 10mm at (rectangle) and extraction regions shaping of: Grain removal (area 100 [mu] m ² or less removed)
If it is not possible to visually determine whether the surface is a flat surface, the squeegee should not apply a load to the translucent adherend having a smooth surface on the surface (α) of the resin layer as much as possible. The interface between the smooth surface 100a of the translucent adherend 100 and the surface (α) 12a of the resin layer 12 was photographed from the W direction of FIG. 4B, and the surface (α) 12 was photographed. Of these, the portion affixed with the smooth surface 100a was determined to be a flat surface.

<Area ratio occupied by flat surface or recess>
The "area ratio (%) occupied by the flat surface" and the "area ratio (%) occupied by the concave portion" with respect to the total area of the region (D) were calculated. The results of the evaluation are shown in Table 4.
In addition, the physical property values for the following evaluation items (d1) to (d2) and (e1) to (e2) were calculated or evaluated. The results of these evaluations are shown in Table 4.

<Evaluation of the areas of flat surfaces and recesses existing in region (D)>
-Evaluation item (d1): Whether or not a flat surface having an ^{area of 0.2 mm 2 or more exists in the region (D) was evaluated according to the following criteria.}
A +: There are a plurality of flat surfaces having an area of 0.4 mm ^{2 or more.}
A: There is one flat surface having an area of 0.4 mm ² or more, and there are a plurality of flat surfaces having an ^{area of 0.2 mm 2} or more and ^{less than 0.4 mm 2.}
B +: There are a plurality of flat surfaces having an area of 0.2 mm ² or more and ^{less than 0.4 mm 2.}
B: There is one flat surface having an area of 0.2 mm ² or more and ^{less than 0.4 mm 2.}
C: The maximum value of the area of the flat surface existing in the region (D) is less than ^{0.2 mm 2.}

-Evaluation item (d2): The area ratio of the amorphous flat surface existing in the region (D) to the total area of the flat surface existing in the region (D) was calculated and evaluated according to the following criteria.
A +: The area ratio occupied by the amorphous flat surface is 100%.
A: The area ratio occupied by the amorphous flat surface is 90% or more and less than 100%.
B: The area ratio occupied by the amorphous flat surface is 80% or more and less than 90%.
C: The area ratio occupied by the amorphous flat surface is less than 80%.

-Evaluation item (e1): The area ratio occupied by the recess having the maximum area in the region (D) with respect to the total area of the recess existing in the region (D) was calculated from the following formula.
[Area ratio (%) occupied by the recess having the maximum area] = [Area of the recess having the maximum area] / [Total area of the recess] × 100

-Evaluation item (e2): The area ratio occupied by the irregular concave portion existing in the region (D) to the total area of the concave portion existing in the region (D) was calculated and evaluated according to the following criteria.
A +: The area ratio occupied by the amorphous recess is 100%.
A: The area ratio occupied by the amorphous recess is 90% or more and less than 100%.
B: The area ratio occupied by the amorphous recess is 80% or more and less than 90%.
C: The area ratio occupied by the amorphous recess is less than 80%.

(4) Measurement and calculation of physical property values for the flat surface (S) existing in the region (D) <skewness Sk value for the flat surface (S)>
A flat surface with a cumulative relative frequency of 30% or less, which is obtained by adding the relative frequency from the smaller area of each flat surface based on the value of each area of the plurality of flat surfaces existing in the region (D) measured in (2) above. One or more flat surfaces (S) excluding the above were selected.
Then, for the area of each flat surface (S) selected, the skewness Sk value with respect to the normal distribution curve of the area and frequency of each flat surface (S) is calculated by graph software (Microsoft Japan stock) based on the following formula (2). Calculated using company, Excel).
That is, the obtained data on the area of each recess and the area of each flat surface were arranged using graph software (Excel, manufactured by Microsoft Japan Co., Ltd.).
Then, from the data, the data of the "flat surface (S)" excluding the flat surface having the cumulative relative frequency of 30% or less, which is the sum of the relative frequencies from the smaller area of each flat surface, was extracted. Then, the average value of the measured values of the area of the flat surface (S) was calculated.
Further, when the total area of the flat surface (S) is 100, the standard deviation with respect to the average value of the area of the flat surface (S) and the skewness with respect to the normal distribution curve of each area and frequency of the flat surface (S). The Sk value and the kurtosis Ku value were calculated. The results of these calculations are shown in Table 4.
Then, for the area of each flat surface (S) selected, the skewness Sk value with respect to the area (or peripheral length) of each flat surface (S) and the normal distribution curve of frequency is based on the following equation (2), and the kurtosis Ku. The value was calculated using graph software (Microsoft Japan Co., Ltd., Excel) based on the following formula (3).
The translucent adherend 100 having a smooth surface 100a is made of non-alkali glass (product name "Eagle XG (registered trademark)", manufactured by Corning Inc.) in the same manner as the "adhesive having a smooth surface". used.

〔式（２）中、ｎは平坦面（Ｓ）の個数、ｘ_ｉは、各平坦面（Ｓ）の各々の面積（ｉ：１，２，・・・ｎ）、μは各平坦面（Ｓ）の面積の平均値、ｓは標本標準偏差を示す。〕

[In the formula (2), n is the number of flat surfaces (S), x _i is the area of each flat surface (S) (i: 1, 2, ... n), and μ is each flat surface ( S) is the average value of the area, and s is the sample standard deviation. ]

<Kurtosis Ku value for flat surface (S)>
A flat surface with a cumulative relative frequency of 30% or less, which is obtained by adding the relative frequency from the smaller area of each flat surface based on the value of each area of the plurality of flat surfaces existing in the region (D) measured in (3) above. One or more flat surfaces (S) excluding the above were selected.
Then, for the area of each flat surface (S) selected, the kurtosis Ku value with respect to the normal distribution curve of the area and frequency of each flat surface (S) is calculated by graph software (Microsoft Japan stock) based on the following formula (3). Calculated using company, Excel).

〔式（３）中、ｎは平坦面（Ｓ）の個数、ｘ_ｉは各平坦面（Ｓ）の各々の面積（ｉ：１，２，・・・ｎ）、μは各平坦面（Ｓ）の面積の平均値、ｓは標本標準偏差を示す。〕

[In the formula (3), n is the number of flat surfaces (S), x _i is the area (i: 1, 2, ... N) of each flat surface (S), and μ is each flat surface (S). ) Indicates the average value, and s indicates the sample standard deviation. ]

<Evaluation of the presence of recesses having a maximum height difference of 0.5 μm or more on the surface (α)>
It is perpendicular to the region (D) surrounded by an arbitrarily selected rectangle of 8 mm in length × 10 mm in width on the surface (α) of the resin layer of the pressure-sensitive adhesive sheet with a base material produced in Examples and Comparative Examples. Using a scanning electron microscope (manufactured by Hitachi, Ltd., product name "S-4700"), the height difference of each concave portion existing in the cross section of the pressure-sensitive adhesive sheet with a base material obtained by cutting the region (D) on a flat surface is measured. Observation was performed under the conditions of an acceleration voltage of 5 kV and a magnification of 500 times, and two cross-sectional images were acquired.
With this cross-sectional image, whether or not there is a recess having a maximum height difference of 0.5 μm or more on the surface (α) 12a side was evaluated according to the following criteria.
A: There is a recess having a maximum height difference of 0.5 μm or more.
F: There is no recess having a maximum height difference of 0.5 μm or more.

<Mass retention of the resin layer of the adhesive sheet>
After obtaining a simple substance of the resin layer from the pressure-sensitive adhesive sheet, the mass of the resin layer before heating was measured. Then, the resin layer was put into a muffle furnace (manufactured by Denken Co., Ltd., product name "KDF-P90") and heated at 800 ° C. for 30 minutes. Then, the mass of the resin layer after heating was measured, and the mass retention rate of the resin layer was calculated by the following formula. The values are shown in Table 4.
Mass retention rate of resin layer (%) = [mass of resin layer after heating] / [mass of resin layer before heating] x 100

<Air release>
An adhesive sheet with a base material measuring 50 mm in length and 50 mm in width is attached to a melamine-coated plate, which is an adherend, so that an air pool is generated, and the area around the air pool is strongly crimped with a squeegee or weakly crimped. Two kinds of cases were prepared. Then, the presence or absence of an air pool after sticking to remove the air pool using a squeegee was observed, and the air bleeding property of each adhesive sheet was evaluated according to the following criteria. The evaluation results are shown in Table 4.
5: The air pool disappears in both the case of weak crimping and the case of strong crimping.
4: When crimped weakly, the air pool disappears. When crimped strongly, most of the air pool disappears, and the remaining air pool also disappears when crimped again.
3: When crimped weakly, the air pool disappears. On the other hand, when the pressure is strongly crimped, there is a part where an air pool remains.
2: When crimped weakly, most of the air pool disappears, and the remaining air pool also disappears when crimped again. On the other hand, when crimped strongly, an air pool remains.
1: An air pool remains in both the case of weak crimping and the case of strong crimping.

<Adhesive strength>
After cutting the pressure-sensitive adhesive sheet with a substrate produced in Examples and Comparative Examples into a size of 25 mm in length × 300 mm in width, the surface (α) of the resin layer of the pressure-sensitive adhesive sheet is heated at 23 ° C. and 50% RH (relative humidity). It was affixed to a stainless steel plate (SUS304, No. 360 polished) under the same environment, and left to stand for 24 hours in the same environment. After standing still, the adhesive strength of each adhesive sheet was measured at a tensile speed of 300 mm / min by a 180 ° peeling method based on JIS Z0237: 2000. The measurement results are shown in Table 4.

<Blister resistance>
An adhesive sheet with a base material measuring 50 mm in length × 50 mm in width is attached to a polymethylmethacrylate plate (manufactured by Mitsubishi Rayon Co., Ltd., product name “Acrylite L001”) having a size of 70 mm in length × 150 mm in width × 2 mm in thickness. A test sample was prepared by strongly crimping with.
This test sample was allowed to stand at 23 ° C. for 12 hours, then allowed to stand in a hot air dryer at 80 ° C. for 1.5 hours, and further allowed to stand in a hot air dryer at 90 ° C. for 1.5 hours to promote heating. The state of blister generation was visually observed, and the blister resistance of each pressure-sensitive adhesive sheet was evaluated according to the following criteria. The evaluation results are shown in Table 4.
A: No blister was confirmed.
B: Blister was partially confirmed.
C: Blister was confirmed on the entire surface.

Since the adhesive sheets of Examples 1 to 4 have the recesses and the flat surface specified in the requirements (Ii) and (Iii), they have excellent air bleeding property that can easily remove the air pool that may occur. As a result, the adhesive properties can be expressed in a well-balanced manner.
On the other hand, the pressure-sensitive adhesive sheets of Comparative Examples 1 to 4 were inferior in air bleeding property as compared with the pressure-sensitive adhesive sheets of Examples.

5 (a) and 6 to 12 show an arbitrarily selected vertical 8 mm × of the exposed surface (α) of the resin layer of the pressure-sensitive adhesive sheet produced in Examples 1 to 4 and Comparative Examples 1 to 4, respectively. It is a binarized image of the image obtained by photographing the region (D) surrounded by the width 10 mm from the surface (α) side using a digital microscope.
That is, the vertical and horizontal directions of the images of FIGS. 5 (a) and 6 to 12 correspond to "8 mm".
Further, in these binarized images, the black portion corresponds to a flat surface and the white portion corresponds to a concave portion.

FIG. 5B is a cross-sectional image obtained by observing a cross section of the pressure-sensitive adhesive sheet produced in Example 1 using a scanning microscope.

The pressure-sensitive adhesive sheet according to one aspect of the present invention is useful as a pressure-sensitive adhesive sheet having a large sticking area, which is used for identification or decoration, for coating masking, for surface protection of metal plates and the like.

1a, 11a, 12a, 1b, 2a, 2b Adhesive sheet 11 Base material 12 Resin layer 12a Surface (α)
12b surface (β)
(X) Resin part (X)
(Y) Particle part (Y)
(Xβ) A layer (Xβ) mainly containing a resin portion (X)
(Xα) A layer (Xα) mainly containing a resin portion (X)
(Y1) A layer (Y1) containing 15% by mass or more of a particle portion (Y).
13, 13a, 131, 132 Concave 14 Flat surface 15 Convex 100 Translucent adherend 100a Smooth surface 101 Adhesive

Claims (18)

A pressure-sensitive adhesive sheet having a resin layer on a base material or a release material, and at least the surface (α) of the resin layer on the side opposite to the side on which the base material or the release material is provided has adhesiveness.
On the surface (α) of the resin layer, there is one or more flat surfaces (f1) having a width that can be selected from the recess and the range surrounded by a circle having a diameter of 100 μm by observation from the surface (α) side. The shape of the flat surface is irregular,
To the total area of 100% of the flat surface on the surface (alpha), the area ratio of the flat surface of the amorphous on the surface (alpha) is Ri 80% to 100% der,
An adhesive sheet in which the resin layer contains a resin portion (X) containing a resin as a main component and a fine particle portion (Y) composed of fine particles. The pressure-sensitive adhesive sheet according to claim 1, wherein one or more flat surfaces (f2) having an area of ^{0.2 mm 2} or more are present on the surface (α) of the resin layer. In a region (D) of 8 mm in length × 10 mm in width arbitrarily selected on the surface (α), an area of 70 to 99.99% is set with respect to 100% of the total area of the recesses existing in the region (D). The adhesive sheet according to claim 1 or 2, wherein the recess is present. A plurality of flat surfaces exist in an arbitrarily selected region (D) of 8 mm in length × 10 mm in width on the surface (α), and the cumulative relative skewness is added from the smaller area of the plurality of flat surfaces. Any one of claims 1 to 3, wherein the skewness Sk value with respect to the normal distribution curve of each area and frequency of one or more flat surfaces (S) excluding the flat surface of 30% or less is 1.0 or more. Adhesive sheet as described in the section. The adhesive sheet according to claim 4, wherein the kurtosis Ku value with respect to the normal distribution curve of each area and frequency of one or more flat surfaces (S) is 1.8 or more. The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein a plurality of the flat surfaces are present on the surface (α), and the positions where the plurality of flat surfaces are present do not have periodicity. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the recess has a height difference of 0.5 μm or more at the maximum. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the recess is not formed by using a release material having an embossed pattern. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the resin layer has a mass retention rate of 3 to 90% by mass after heating at 800 ° C. for 30 minutes. The pressure-sensitive adhesive sheet according to any one of claims 1 to 9, wherein the resin contained in the resin portion (X) contains a pressure-sensitive adhesive resin. The pressure-sensitive adhesive sheet according to any one of claims 1 to 10 , wherein the resin portion (X) further contains one or more selected from a metal chelate-based cross-linking agent and an epoxy-based cross-linking agent. The pressure-sensitive adhesive sheet according to any one of claims 1 to 11 , wherein the fine particles are one or more selected from silica particles, metal oxide particles, and smectite. The pressure-sensitive adhesive sheet according to any one of claims 1 to 12 , wherein the surface (β) of the resin layer on the side provided with the base material or the release material has adhesiveness. From the side where the base material or the release material is provided, the resin layer mainly contains a layer (Xβ) containing a resin portion (X), a layer (Y1) containing 15% by mass or more of a particle portion (Y), and mainly. The pressure-sensitive adhesive sheet according to any one of claims 1 to 13 , which is a multilayer structure in which layers (Xα) including a resin portion (X) are laminated in this order. The layer (Xβ) is a layer formed from a composition (xβ) containing a resin and having a fine particle content of less than 15% by mass.
The layer (Y1) is a layer formed from the composition (y) containing 15% by mass or more of fine particles.
The pressure-sensitive adhesive sheet according to claim 14 , wherein the layer (Xα) is a layer formed of a composition (xα) containing a resin and having a fine particle content of less than 15% by mass. The method for producing an adhesive sheet according to any one of claims 1 to 15 , which comprises at least the following steps (1) and (2).
Step (1): A coating film (x') containing a resin and having a fine particle content of less than 15% by mass (x), and a coating film (y) containing 15% by mass or more of fine particles. Step of forming (y') Step (2): Step of simultaneously drying the coating film (x') and the coating film (y') formed in the step (1). The method for producing an adhesive sheet according to claim 16 , which comprises at least the following steps (1A) and (2A).
Step (1A): A coating film (xβ') comprising a composition (xβ) containing a resin and having a fine particle content of less than 15% by mass on a substrate or a release material, and a composition containing 15% by mass or more of the fine particles. A coating film (y') composed of a substance (y) and a coating film (xα') composed of a composition (xα) containing a resin and having a fine particle content of less than 15% by mass are laminated and formed in this order. Step Step (2A): Step of simultaneously drying the coating film (xβ'), the coating film (y'), and the coating film (xα') formed in the step (1A). The method for producing an adhesive sheet according to claim 16 , which comprises at least the following steps (1B) and (2B).
Step (1B): A coating film (y) comprising a composition (y) containing 15% by mass or more of the fine particles on a layer (Xβ) mainly containing a resin portion (X) provided on a base material or a release material. Step (2B): Step (1B) of laminating and forming a coating film (xα') composed of a composition (xα) containing y') and a resin and having a fine particle content of less than 15% by mass in this order. ) And the coating film (xα') formed in) at the same time.

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