JP6898041B2 - Adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet.

Adhesive sheets having an adhesive layer on a base material are used for various purposes such as for labels and temporary fixing. Such adhesive sheets often have different required performance depending on the application and the situation.
For example, a temporary fixing tape used for temporarily fixing a part, a decorative tape that is supposed to be replaced after a certain period of time has passed after being attached, and the like are required to have excellent adhesive strength when attached to an adherend. On the other hand, at the time of peeling, good re-peeling property that can be easily peeled off with a small force is required.
Therefore, an adhesive sheet having excellent removability that can be easily peeled off at the time of peeling while exhibiting excellent adhesive strength at the time of sticking has been developed.

For example, Patent Document 1 discloses a pressure-sensitive adhesive having two pressure-sensitive adhesive layers. The pressure-sensitive adhesive has a first microcapsule in which one pressure-sensitive adhesive layer contains a release agent capable of reducing the pressure-sensitive adhesive strength together with the pressure-sensitive adhesive material and melts at a predetermined temperature, and the other pressure-sensitive adhesive layer. Contains a second microcapsule that contains an adhesive material and a release agent that can reduce the adhesive strength and melts at a predetermined temperature, and a curing agent that cures the adhesive material and melts at a predetermined temperature. It has a third microcapsule.
According to Patent Document 1, by providing a pressure-sensitive adhesive having two layers of pressure-sensitive adhesive layers having microcapsules containing such a release agent, when peeling off, only heat treatment is performed at a predetermined temperature. Therefore, it is said that it can be easily peeled off from the adherend without leaving a residue on the adherend.

Japanese Unexamined Patent Publication No. 2008-138108

However, in the adhesive described in Patent Document 1, since the microcapsules containing the release agent that lowers the adhesive strength melt at a certain temperature or higher and the adhesive strength decreases, the adherend during manufacturing, storage, and the like. It becomes necessary to control the temperature environment at the time of sticking to, and it is not suitable for use in a high temperature environment. Therefore, the use environment of the pressure-sensitive adhesive described in Patent Document 1 is limited.

The present invention provides an adhesive sheet having excellent removability that can be easily peeled off from the adherend while exhibiting excellent adhesive strength when the adherend is attached to the adherend regardless of the usage environment. The purpose is to provide.

The present inventors have solved the above-mentioned problems by using a base material having an uneven surface designed in advance so that the adhesive strength differs depending on the peeling direction, and an adhesive sheet in which an adhesive layer is directly laminated on the uneven surface. Found to get.

That is, the present invention relates to the following [1] to [6].
[1] An adhesive sheet having a base material having an uneven surface and an adhesive layer directly laminated on the uneven surface of the base material, and satisfying the following requirement (I).
Requirement (I): After the adhesive sheet is attached to an adherend, the adhesive sheet is peeled and measured at a peeling angle of 180 ° along an arbitrarily selected x direction in accordance with JIS Z0237: 2000. Adhesive force (Nx) [N / 25 mm], adhesive force (Ny) [N / 25 mm] of the adhesive sheet measured by peeling along the y direction, and the angle formed by the x direction and the y direction is θ (0 ° < When θ ≦ 180 °), there is at least one θ having an adhesive force change degree of 10 or more with respect to the average value of the adhesive force (Nx) and (Ny) calculated from the following formula (F1).
Formula (F1): Degree of change in adhesive strength = | Nx-Ny | / ((Nx + Ny) / 2) x 100
[2] The pressure-sensitive adhesive sheet according to the above [1], wherein the base material is a fiber base material having an uneven surface in which a plurality of fibers are present.
[3] The fiber base material is a raised base material having a concavo-convex surface in which raised fibers are present, or a flocked base material having a concavo-convex surface in which the flocked fibers are present, which is composed of a fibrous material. Adhesive sheet described in.
[4] The ratio of the average height of the fibers to the thickness of the pressure-sensitive adhesive layer with respect to the surface (α), which is the surface including the fixed end to which the fibers constituting the fiber base material are fixed. The pressure-sensitive adhesive sheet according to the above [2] or [3], wherein the average height of the fibers / thickness of the pressure-sensitive adhesive layer] is 0.4 to 0.99.
[5] The pressure-sensitive adhesive sheet according to the above [1], wherein the base material is an embossed base material having an uneven surface in which concave portions and convex portions are present.
[6] In the cross section obtained by cutting the embossed base material in the thickness direction, the average height difference (H1) between the concave portion and the convex portion existing on the uneven surface is 5 to 200 μm. The described adhesive sheet.

The adhesive sheet of the present invention uses a base material having an uneven surface designed in advance so that the adhesive strength differs depending on the peeling direction, so that excellent adhesive strength is exhibited at the time of sticking to the adherend regardless of the usage environment. However, when peeling, if it is peeled along a predetermined direction, it can be easily peeled and has excellent re-peeling property.

It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet of this invention. FIG. 5 is a schematic cross-sectional view showing a process of attaching the pressure-sensitive adhesive sheet of the present invention to an adherend and then peeling it off along the x direction. FIG. 5 is a schematic plan view of the pressure-sensitive adhesive sheet attached to the adherend shown in FIG. 2A when observed from the base material side. This is an example of a schematic cross-sectional view when the pressure-sensitive adhesive sheet having a fiber base material, which is one aspect of the present invention, is cut perpendicularly to the sticking surface to be stuck to the adherend of the pressure-sensitive adhesive layer. It is a cross-sectional schematic diagram of the pressure-sensitive adhesive sheet when the pressure-sensitive adhesive sheet having a fiber base material which is one aspect of this invention is attached to an adherend. This is an example of a schematic cross-sectional view when focusing on two fibers among the plurality of fibers shown in FIG. FIG. 5 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet obtained by cutting a pressure-sensitive adhesive sheet having an embossed base material, which is one aspect of the present invention, on a surface where concave portions and convex portions existing on an uneven surface can be discriminated. It is a plane schematic diagram which shows an example when viewed in a plan view from the uneven surface side of the concave-convex surface used in one aspect of this invention. It is a plane schematic diagram which shows an example when viewed in a plan view from the uneven surface side of the concave-convex surface used in one aspect of this invention.

The pressure-sensitive adhesive sheet of the present invention has a base material having an uneven surface and an adhesive layer directly laminated on the uneven surface of the base material.
FIG. 1 is a schematic cross-sectional view showing an example of the configuration of the pressure-sensitive adhesive sheet of the present invention. In FIG. 1, the uneven shape of the uneven surface 11 of the base material 10 is omitted.

Examples of the structure of the pressure-sensitive adhesive sheet of the present invention include a pressure-sensitive adhesive sheet 1a in which the pressure-sensitive adhesive layer 20 is directly laminated on the uneven surface 11 of the base material 10 as shown in FIG. 1 (a).
Further, as shown in FIG. 1B, the pressure-sensitive adhesive sheet 1b may be obtained by further laminating the release material 30 on the sticking surface 21 of the pressure-sensitive adhesive layer 20.
Further, as shown in FIG. 1C, the adhesive layer 20 and the release material 30 are laminated on the uneven surface 11 by using the base material 10 having the uneven surfaces 11 and 11'on both sides, and the uneven surface 11 is formed. The pressure-sensitive adhesive sheet 1c on which the pressure-sensitive adhesive layer 20'and the release material 30'are laminated may be used. The adhesive sheet 1c has a function as a double-sided tape.

The pressure-sensitive adhesive sheet of the present invention satisfies the following requirement (I).
-Requirement (I): After the adhesive sheet is attached to an adherend, the adhesive sheet is peeled and measured along an arbitrarily selected x direction at a peeling angle of 180 ° in accordance with JIS Z0237: 2000. Adhesive force (Nx) [N / 25 mm], adhesive force (Ny) [N / 25 mm] of the adhesive sheet measured by peeling along the y direction, and the angle formed by the x direction and the y direction is θ (0 °). When <θ≤180 °), there is at least one θ having an adhesive force change degree of 10 or more with respect to the average value of the adhesive force (Nx) and (Ny) calculated from the following formula (F1). ..
Formula (F1): Degree of change in adhesive strength = | Nx-Ny | / ((Nx + Ny) / 2) x 100

Here, with respect to the operation defined in the requirement (I), "after the adhesive sheet is attached to the adherend, the adhesive sheet is peeled off along an arbitrarily selected x direction at a peeling angle of 180 °", FIG. It will be described using. Also in FIG. 2, the uneven shape of the uneven surface 11 of the base material 10 is omitted.
First, as shown in FIG. 2A, after the sticking surface 21 of the pressure-sensitive adhesive layer 20 of the pressure-sensitive adhesive sheet 1 is stuck to the adherend 500, the pressure-sensitive adhesive sheet is attached to the adherend from the start point A to the end point B. Consider the case of peeling from 500.
FIG. 2B shows the process of peeling the adhesive sheet 1 from the adherend 500 from the start point A toward the end point B, and the direction from the start point A to the end point B is the “peeling direction”. , In FIG. 2B, the peeling direction is the “direction x”.

FIG. 3 is a schematic plan view of the adhesive sheet attached to the adherend shown in FIG. 2A when observed from the base material side.
As shown in FIG. 3, when the adherend 500 is peeled off from the adherend 500 along the x direction arbitrarily selected under the above measurement conditions, the measured adhesive force is "adhesive force (Nx)" and is in the y direction. The adhesive force measured when the adherend 500 is peeled off along the line is "adhesive force (Ny)".
The adhesive strength (Nx) and (Ny) are values measured at a peeling angle of 180 ° in accordance with JIS Z0237: 2000, and specific measurement conditions are as described in Examples.
Further, the angle θ shown in FIG. 3 indicates the angle formed by the x direction and the y direction, and is selected in the range of 0 ° <θ ≦ 180 °.

The pressure-sensitive adhesive sheet of the present invention has at least one θ having a degree of change in adhesive strength of 10 or more with respect to the average value of adhesive strength (Nx) and (Ny) calculated from the above formula (F1).
The degree of change in adhesive strength calculated from the above formula (F1) indicates the ratio of the difference in adhesive strength (Nx) and (Ny) to the average value of adhesive strength (Nx) and (Ny). It can be said that the larger the value of the degree of change in adhesive strength, the greater the difference in adhesive strength depending on the peeling direction.

The adhesive sheet of the present invention is designed so that the uneven surface of the base material has at least one θ having an adhesive force change degree of 10 or more, so that the adhesive force differs depending on the peeling direction. ing.
Therefore, the adhesive sheet of the present invention exhibits excellent adhesive strength when attached to the adherend regardless of the usage environment, but when peeled off, it is only slightly peeled off in the direction of low adhesive strength. It can be easily peeled off with a strong force and has excellent re-peelability.
For example, when the adhesive force (Nx) in the x direction is larger than the adhesive force (Ny) in the y direction, the adhesive force (Nx) in the x direction is high at the time of sticking to the adherend, so that the adhesive force (Nx) is high with the adherend. Adhesion is maintained well. On the other hand, when peeling from the adherend, if the peeling is performed along the y direction, the peeling can be easily performed with a slight force.
On the other hand, a general adhesive sheet has an adhesive force change degree of less than 10 specified in the above requirement (I), and is designed so that it can be peeled off with almost the same force regardless of the direction in which it is peeled off. ..
Therefore, regarding the structure of a general pressure-sensitive adhesive sheet, if the adhesive strength is increased, the residue of the adhesive layer adheres to the adherend and the re-peelability is deteriorated, and if the adhesive strength is lowered, the adhesive strength is lowered. Since the adhesion to the adherend is inferior, there is a problem in the balance between the adhesive strength and the removability.

In one aspect of the present invention, the degree of change in adhesive strength calculated from the above formula (F1) is 10 or more, preferably 30 or more, more preferably 50 or more, still more preferably 70 or more, still more preferably 70 or more. It is 85 or more.
Further, the degree of change in adhesive strength calculated from the above formula (F1) is preferably 200 or less, more preferably 180, from the viewpoint of the balance between the adhesive strength at the time of sticking to the adherend and the re-peelability at the time of peeling. Below, it is more preferably 150 or less, still more preferably 130 or less.

The pressure-sensitive adhesive sheet of the present invention has a structure in which a pressure-sensitive adhesive layer is directly laminated on the uneven surface of the base material using a base material having an uneven surface designed to satisfy the requirement (1). That is, the requirement (I) can be said to be a requirement regarding the uneven surface of the base material.
The pressure-sensitive adhesive sheet using a base material having an uneven surface designed to satisfy the requirement (I) is deformed by the pressure-sensitive adhesive and the convex portion when peeled off due to the convex shape of the surface of the base material laminated with the pressure-sensitive adhesive layer. It is considered that the force required for peeling differs depending on the direction because of the difference. Further, since the peeling area can be controlled at each moment by having the convex portions having different shapes, it is considered that the force required for peeling can be different depending on the direction.

On the other hand, a general adhesive sheet is often intended to develop a uniform adhesive force without bias over the entire surface of the sticking surface, and has a structure in which an adhesive layer is laminated on a flat surface of a base material. In most cases. The degree of change in adhesive strength specified in the requirement (I) of the adhesive sheet having such a configuration is less than 10.
For the purpose of developing a uniform adhesive force, it is unlikely to design an adhesive sheet in which a base material having an uneven surface is used and an adhesive layer is laminated on the uneven surface.

From the viewpoint of designing an adhesive sheet satisfying the requirement (I), the base material used in the present invention is preferably a base material having an uneven surface as described below.
-A fiber base material having an uneven surface in which a plurality of fibers are present.
-Embossed base material having an uneven surface with concave and convex portions.
Hereinafter, the fiber base material and the embossed base material will be described.

<Fiber base material>
From the viewpoint of designing the pressure-sensitive adhesive sheet satisfying the requirement (I), the base material of the pressure-sensitive adhesive sheet according to one aspect of the present invention is preferably a fiber base material having an uneven surface in which a plurality of fibers are present.
The fiber base material used in one aspect of the present invention may be one in which a plurality of fibers are present on at least one surface, and may be one in which a plurality of fibers are present on both sides.
In the present invention, the "fiber" refers to an elongated solid having an aspect ratio of 3 or more, and may be a natural fiber (vegetable fiber, animal fiber, etc.) or a chemical fiber (synthetic fiber, semi-synthetic fiber, regenerated fiber, etc.). Inorganic fiber, etc.) may be used.

In the present specification, the aspect ratio of a fiber (including "raised fiber" and "flocked fiber" described later) means a value calculated from the "length" / "thickness" of the target fiber.
The aspect ratio of the fibers can be measured by observing the fibers existing in the base material before being integrated with the pressure-sensitive adhesive layer using an optical microscope, an electron microscope, or the like.
If a part of the target fiber is entangled with other fibers and it is difficult to measure the "length", the length of only the part of the target fiber whose thickness can be measured is measured. The aspect ratio of the portion may be 3 or more.

In the following description of the fiber base material, the "concavo-convex surface" refers to the entire surface on the side where the support constituting the fiber base material and the plurality of fibers including the plurality of fibers are present. On the other hand, the "surface (α)" refers to the surface including the fixed end portion to which the fibers constituting the fiber base material are fixed, and the surface of the support portion to which the plurality of fibers are fixed.

Specific fibers constituting the uneven surface of the fiber base material include, for example, plant fibers such as cotton and hemp; animal fibers such as silk and wool; polyolefin fibers such as polyester fibers, polypropylene fibers and polyethylene fibers. , Vinylon fiber, acrylic fiber, urethane fiber, polyamide fiber such as nylon fiber, vinyl chloride fiber, synthetic fiber formed from thermoplastic resin such as acrylonitrile fiber; semi-synthetic fiber such as acetate; rayon Regenerated fibers such as carbon fibers, inorganic fibers such as glass fibers; and the like.

The average length of the plurality of fibers constituting the fiber base material is preferably 1 to 5000 μm, more preferably 50 to 1000 μm, still more preferably 100 to 800 μm, and even more preferably 150 to 650 μm.
The average thickness of the plurality of fibers constituting the fiber base material is preferably 1 to 70 μm, more preferably 3 to 60 μm, still more preferably 5 to 50 μm, and even more preferably 10 to 30 μm.
The average aspect ratio of the plurality of fibers constituting the fiber base material is preferably 3 or more, more preferably 5 to 1000, more preferably 10 to 700, still more preferably 20 to 500, still more preferably 30 to 200. is there.

The above-mentioned "fiber length" refers to the length in the longitudinal direction when the target fiber is stretched in a straight line.
In the present specification, the "length", "thickness" and "aspect ratio" of 10 to 100 fibers arbitrarily selected from a plurality of fibers on the uneven surface of the fiber base material are measured, and these are measured. The average value of may be regarded as "average length of a plurality of fibers", "average thickness of a plurality of fibers" and "average aspect ratio of a plurality of fibers", respectively.
In addition, the length, thickness, and aspect value of the fiber can be measured by observing a cross section of the target fiber base material perpendicular to the uneven surface with an optical microscope or an electron microscope. it can.
Then, this cross section may be obtained by cutting in a state of being laminated with the pressure-sensitive adhesive layer, or may be obtained by cutting only the fiber base material before laminating the pressure-sensitive adhesive layer.

The fiber base material used in one aspect of the present invention is preferably a base material in which the plurality of fibers protrude from the surface (α) from the viewpoint of forming an adhesive sheet satisfying the requirement (I).
The above-mentioned "plurality of fibers protruding from the surface (α)" means that the target fiber is from the fixed end fixed to the surface (α) of the base material to the other end. , Means a state in which the shape of a fiber having an aspect ratio of 3 or more can be confirmed.
In addition, whether or not "a plurality of fibers are protruding from the surface (α)" is determined by observing a cross section of the target base material cut perpendicular to the surface (α) with an optical microscope, an electron microscope, or the like. It can be confirmed by.
This cross section may be obtained by cutting in a state of being laminated with the pressure-sensitive adhesive layer, or may be obtained by cutting only the base material before laminating the pressure-sensitive adhesive layer.

In the pressure-sensitive adhesive sheet of one aspect of the present invention, when the pressure-sensitive adhesive layer is formed on the uneven surface of the fiber base material, the pressure-sensitive adhesive sheet satisfies the above requirement (I) in consideration of the following items. It is preferable to form an agent layer.
-Before forming the pressure-sensitive adhesive layer, a fiber base material having an uneven surface in which a plurality of fibers already oriented along a predetermined direction (x) are present is used.
-Before forming the pressure-sensitive adhesive layer, a plurality of fibers existing on the uneven surface of the fiber base material are brushed along a predetermined direction (x) using a brush or a brush.
-The pressure-sensitive adhesive layer, which is a material for forming the pressure-sensitive adhesive layer, is applied and formed on the uneven surface of the fiber base material along a predetermined one direction (x) to form the pressure-sensitive adhesive layer.

FIG. 4 is an example of a schematic cross-sectional view when the pressure-sensitive adhesive sheet having a fiber base material, which is one aspect of the present invention, is cut perpendicularly to the sticking surface to be stuck to the adherend of the pressure-sensitive adhesive layer.
The pressure-sensitive adhesive sheet 2 shown in FIG. 4 is an example of an embodiment in which the pressure-sensitive adhesive layer 20 is formed on the uneven surface of the fiber base material 10A in consideration of the above items.
Like the pressure-sensitive adhesive sheet shown in FIG. 4, a plurality of fibers 12 integrated with the pressure-sensitive adhesive layer 20 are in a state of being oriented along a predetermined one direction (p) inside the pressure-sensitive adhesive layer 20. Therefore, it is easy to adjust to an adhesive sheet that satisfies the requirement (I).

FIG. 5 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet when the pressure-sensitive adhesive sheet having a fiber base material, which is one aspect of the present invention, is attached to an adherend.
As shown in FIG. 5A, when the adhesive sheet 2 is peeled from the adherend 500, it is attempted to peel off along the x direction, which is the same direction as the one direction (p) in which the plurality of fibers 12 are oriented. If so, it can be easily peeled off. In this case, the adhesive strength (Nx) of the pressure-sensitive adhesive sheet measured by peeling along the x direction, which is the same direction as the direction (p) in which the plurality of fibers 12 are oriented, tends to be the minimum value.

On the other hand, as shown in FIG. 5B, the adhesive sheet 2 is formed by the y direction (angle formed by the x direction and the y direction), which is the direction opposite to the one direction (p) in which the plurality of fibers 12 are oriented. When it is attempted to peel off along (θ is 180 °), it becomes more difficult to peel off than when it is peeled off along the x direction, which is the same direction as one direction (p), and the adhesive strength (Ny) becomes the maximum value. easy.

The "average value of the linear distance between the fixed end portion and the farthest portion" of the fiber integrated with the pressure-sensitive adhesive layer is preferably 1 to 5000 μm, more preferably 50 to 1000 μm, and further preferably 100 to 800 μm. Even more preferably, it is 150 to 600 μm.
In the present specification, the "straight line distance between the fixed end portion and the farthest portion" of the fiber integrated with the pressure-sensitive adhesive layer refers to the length of a straight line connecting the fixed end portion and the farthest portion.
For example, in the fiber 12a of FIG. 6A, the length of the straight line La connecting the surface (α) 11a, the fixed end portion 121a fixed, and the farthest end portion 122a corresponds. Further, in the fiber 12b, the length of the straight line Lb connecting the surface (α) 11a, the fixed end portion 121b fixed, and the farthest portion 123b corresponds.
Further, the average value of the linear distance between the fixed end and the farthest portion of 10 fibers selected arbitrarily shall be regarded as the above-mentioned "average value of the linear distance between the fixed end and the farthest portion of the fiber". You can also.

Further, as the ratio of the average value of the straight line distance between the fixed end portion and the farthest portion to the thickness of the pressure-sensitive adhesive layer of the fiber [average value of the straight line distance / thickness of the pressure-sensitive adhesive layer], the fibers are oriented. From the viewpoint of making the adhesive sheet easily peelable by peeling along the direction (p) and satisfying the requirement (I), it is preferably more than 0.5, more preferably 0.6 or more, and further preferably 0. It is 8.8 or more, more preferably 1.0 or more, particularly preferably 1.2 or more, and from the viewpoint of flattening the adhesive surface of the pressure-sensitive adhesive layer and exhibiting good adhesive strength, it is preferably 15. It is 0.0 or less, more preferably 10.0 or less, and even more preferably 8.0 or less.

The ratio of the average height of the fibers to the thickness of the pressure-sensitive adhesive layer based on the surface (α) [average height of the fibers / thickness of the pressure-sensitive adhesive layer] is the direction in which the fibers are oriented (the direction in which the fibers are oriented (the thickness of the pressure-sensitive adhesive layer). From the viewpoint of making the adhesive sheet easily peelable by peeling along p) and satisfying the requirement (I), it is preferably 0.4 or more, more preferably 0.5 or more, still more preferably 0.6 or more. , More preferably 0.7 or more, and preferably 1.0 or less, more preferably 0.99 or less.

In this specification, the average height of 10 arbitrarily selected fibers can be regarded as the above-mentioned "average height of fibers".
Further, in the present specification, the "height of the fiber with respect to the surface (α)" refers to the length of the perpendicular line drawn from the top of the fiber to the surface (α).
For example, in the fiber 12a shown in FIG. 6B, since the end portion 122a of the fiber coincides with the topmost portion, the end portion 122a, which is the topmost portion, is lowered to the surface (α) 11a of the fiber base material 10A. The length of the perpendicular ha corresponds to the "height of the fiber 12a".
Further, in a curved fiber such as the fiber 12b, the length of the perpendicular hb drawn from the topmost portion 124b to the surface (α) 11a of the fiber base material 10A corresponds to the “height of the fiber 12b”. In the fiber 12b, the top portion 124b and the end portion 122b do not match. That is, as in the case of the fiber 12b, the "end of the fiber" may not be the "top of the fiber".

In the pressure-sensitive adhesive sheet having the fiber base material of one aspect of the present invention, the ratio of the height of the fibers to the thickness of the pressure-sensitive adhesive layer with respect to the surface (α) [fiber height / It is preferable to contain fibers having a pressure-sensitive adhesive layer thickness of 0.5 or more.
Due to the presence of such fibers, when the fibers are peeled off, if the fibers are peeled off along the direction (p) in which the fibers are oriented, the adhesive sheet can be easily peeled off and satisfies the requirement (I). Can be done.

In the above-mentioned measurement of "straight line distance between the fixed end of the fiber and the farthest part" and "height of the fiber", the fibers on the sticking surface to be stuck to the adherend of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet are oriented. It can be calculated by observing the cross section of the pressure-sensitive adhesive sheet cut perpendicularly to the sticking surface at an arbitrary position along the direction (p) using an optical microscope, an electron microscope, or the like.
These values may be calculated based on an image of a cross section of the pressure-sensitive adhesive sheet obtained by using an optical microscope, an electron microscope, or the like.

In the pressure-sensitive adhesive sheet having the fiber base material of one aspect of the present invention, the thickness of the pressure-sensitive adhesive layer laminated on the uneven surface of the fiber base material is preferably 20 to 1000 μm, more preferably 30 to 600 μm, and further preferably 50 to 50. It is 400 μm.

The fiber base material used in one embodiment of the present invention may be a base material having an uneven surface in which a plurality of fibers are present. For example, the fiber base material is composed of a fibrous material, and the plurality of fibers protrude from the surface (α). Examples thereof include a fiber base material forming an uneven surface.
Examples of the material for forming the fibrous material constituting the fiber base material include the same natural fibers and chemical fibers as those constituting the above-mentioned plurality of fibers.
Regarding the fiber base material, the plurality of fibers and the support portion, which is a portion obtained by removing the plurality of fibers from the fiber base material, may be composed of the same fibers, or may be composed of different fibers. May be.
From the viewpoint of forming the pressure-sensitive adhesive sheet satisfying the requirement (I), the fibrous material constituting the fiber base material is preferably formed from a material having a tensile elastic modulus larger than that of the pressure-sensitive adhesive described later.

Among such fibrous base materials, from the viewpoint of making an adhesive sheet satisfying the requirement (I), a raised base material composed of a fibrous material and having an uneven surface on which brushed fibers are present, or unevenness on which flocked fibers are present. It is preferably a flocked base material having a surface.

(Brushed base material)
As a general rule, the brushed base material is a support portion which is a portion obtained by removing the plurality of fibers constituting the uneven surface and the plurality of fibers from the brushed base material (hereinafter, also referred to as "support portion of the brushed base material"). Is composed of the same fibers as each other.
The raised fibers constituting the uneven surface of the raised base material are fibers formed by applying a raising treatment to the surface of the fibrous material, and at least one end thereof is the surface (α) of the support portion of the raised base material. ) And fixed fibers.
Examples of the fibrous material constituting the brushed base material include fibrous materials formed from the same natural fibers and chemical fibers as those constituting the above-mentioned plurality of fibers, and may be a woven fabric or a non-woven fabric. You may.

The thickness of the support portion of the brushed base material is preferably 100 to 50,000 μm, more preferably 200 to 10000 μm, still more preferably 350 to 5000 μm, and even more preferably 500 to 1000 μm.

The average length of the raised fibers is preferably 1 to 5000 μm, more preferably 50 to 1000 μm, still more preferably 100 to 800 μm, still more preferably 150 to 600 μm.
The above-mentioned "length of raised fibers" refers to the length in the longitudinal direction when the target raised fibers are linearly stretched.

The average thickness of the raised fibers is preferably 1 to 70 μm, more preferably 3 to 60 μm, still more preferably 5 to 50 μm, still more preferably 10 to 30 μm.

The average aspect ratio of the brushed fibers is preferably 5 to 1000, more preferably 10 to 200, still more preferably 20 to 100, and even more preferably 30 to 70.
In the present specification, the "average aspect ratio of raised fibers" means a value calculated from [average length of raised fibers] / [average thickness of raised fibers].

In this specification, the "length", "thickness" and "aspect ratio" of 10 to 100 arbitrarily selected raised fibers are measured from the raised fibers constituting the uneven surface of the raised base material. These average values may be regarded as "average length of raised fibers", "average thickness of raised fibers" and "average aspect ratio of raised fibers", respectively.
In addition, the length, thickness, and aspect value of the raised fibers should be measured by observing a cross section of the target raised base material perpendicular to the uneven surface with an optical microscope or an electron microscope. Can be done.
Then, this cross section may be obtained by cutting in a state of being laminated with the pressure-sensitive adhesive layer, or may be obtained by cutting only the brushed base material before laminating the pressure-sensitive adhesive layer.

The density of the napped fibers present uneven surface brushed substrate, preferably 1 to 1000 present / mm ^2, more preferably 10 to 500 present / mm ^2, more preferably 50-300 present / mm ^2, further more It is preferably 100 to 250 lines / mm ² .
In the present invention, the density of the raised fibers in a predetermined region (for example, a square having a side of 4 mm) arbitrarily selected on the uneven surface of the raised base material may be regarded as the above-mentioned "density of the raised base material". ..

The raising treatment for forming the raised fibers is, for example, a treatment for raising a part of the fibers constituting the fibrous material from at least one surface of the fibrous material, and specifically, the fibrous material. The process of shearing the loops (rings) of the fibers that make up the support, the process of actively pulling out some of the fibers that make up the support by means of needle cloth rolls, sand rolls, sand belts, etc. Examples include a treatment in which the fibers are squeezed out by twisting a plurality of fibers.

(Flocked base material)
The flocked base material used in one aspect of the present invention refers to a base material in which the flocked fibers are present, which are formed by performing a flocking treatment for fixing the flocked fibers on the surface of the support portion.

Examples of the support portion of the flocked base material include paper materials such as high-quality paper, art paper, coated paper, and glassin paper; fabrics such as woven cloth and non-woven fabric; polyolefin resins such as polyethylene resin and polypropylene resin, and polyethylene terephthalate resin. Resin films or sheets formed from polyester resins such as polybutylene terephthalate resin, acetate resins, ABS resins, polystyrene resins, vinyl chloride resins and other thermoplastic resins; metal materials such as aluminum, copper, silver and gold. Be done.
A laminated paper obtained by laminating the above-mentioned paper material with the above-mentioned thermoplastic resin, which is a material for forming a resin film, may be used as a support portion.
Further, the film or sheet laminated with the above-mentioned metal material using the above-mentioned thermoplastic resin, and the surface of the above-mentioned resin film or sheet are vapor-deposited with a metal such as aluminum, copper, silver, or gold. The film or sheet obtained from the above may be used as the support portion.

Examples of the flocked fiber include the same natural fiber and chemical fiber as those constituting the above-mentioned plurality of fibers.
The flocked fiber may be composed of one type or a blended product using two or more types of fibers.

The thickness of the support portion of the flocked base material is preferably 2 to 1000 μm, more preferably 10 to 500 μm, still more preferably 20 to 200 μm, and even more preferably 50 to 100 μm.

The average length of the flocked fibers is preferably 5 to 1200 μm, more preferably 10 to 1000 μm, still more preferably 100 to 800 μm, still more preferably 200 to 600 μm.
The above-mentioned "length of flocked fibers" refers to the length in the longitudinal direction when the target flocked fibers are linearly stretched.

The average thickness of the flocked fibers is preferably 1 to 70 μm, more preferably 3 to 60 μm, still more preferably 5 to 50 μm, still more preferably 10 to 30 μm.

The average aspect ratio of the flocked fibers is preferably 5 to 1200, more preferably 8 to 400, even more preferably 12 to 100, and even more preferably 15 to 30.
In the present specification, the "average aspect ratio of flocked fibers" means a value calculated from [average length of flocked base material] / [average thickness of flocked fibers].

In this specification, the "length", "thickness" and "aspect ratio" of 10 to 100 flocked fibers arbitrarily selected from the flocked fibers existing on the uneven surface of the flocked base material are measured. These average values may be regarded as "average length of flocked fibers", "average thickness of flocked fibers" and "average aspect ratio of flocked fibers", respectively.
In addition, the length, thickness, and aspect value of the flocked fibers should be measured by observing a cross section of the target flocked substrate perpendicular to the uneven surface with an optical microscope or an electron microscope. Can be done.
Then, this cross section may be obtained by cutting in a state of being laminated with the pressure-sensitive adhesive layer, or may be obtained by cutting only the flocked base material before laminating the pressure-sensitive adhesive layer.

The density of the flocked fibers existing on the uneven surface of the flocked base material is preferably 1 to 6000 fibers / mm ² , more preferably 5 to 4000 fibers / mm ² , still more preferably 10 to 2000 fibers / mm ² , and further. It is preferably 100 to 1000 lines / mm ² .
In the present invention, the density of the flocked fibers in a predetermined region (for example, a square having a side of 1 mm) arbitrarily selected on the uneven surface of the flocked base material may be regarded as the above-mentioned "density of the flocked base material". ..

As a flocking treatment for forming flocked fibers on the surface of the support portion, a general method can be used, and examples thereof include the following methods.
-Method by electrostatic flocking method.
-When a cloth such as a woven cloth or a non-woven fabric is used as the support part, a method of sewing flocked fibers on the cloth.
-When using a support part that has a hole into which the flocked fiber is inserted, a method of driving the flocked fiber into the hole on the support part by sandwiching a retaining tool called a flat wire, or flocking in the hole on the support part. A method in which fibers are heat-welded and fixed after being inserted.

Among these, the method by the electrostatic flocking method is preferable from the viewpoint that the flocked fibers can be formed regardless of the type of the support portion.
As a method based on the electrostatic flocking method, for example, an electric field is formed by applying a voltage to the electrodes of the electrostatic flocking machine, and a floc in which the surface made of the above-mentioned flocked fibers is electrodeposited is supplied into the electric field. .. Further, a charged adhesive is applied on a support portion separately installed in the electric field by a spray method, a dip method, or the like to form a charged adhesive layer. Then, the flock is flown, directed toward the adhesive layer formed by applying an adhesive on the support portion, the flock is pierced, and then the adhesive layer is dried and solidified to be dried and solidified on the support portion. Flocked fibers can be transplanted to the hair.
The electrostatic flocking method may be any of a down type, an up type, a retention type, and a spray type (fiber coat).
Further, after flocking, excess flocked fibers existing on the support portion may be removed by air blowing or brushing.

As the flocking fiber used in the electrostatic flocking method, a fiber that can be appropriately charged is preferable, and specifically, a fiber composed of one or more of nylon, rayon, polyester, and acrylic is preferable.

The adhesive used in the electrostatic flocking method may be a solvent-based adhesive or an emulsion-based adhesive.
Examples of the solvent-based adhesive include urethane resin solvent-based adhesives, epoxy resin solvent-based adhesives, vinyl acetate resin solvent-based adhesives, and the like.
Examples of the emulsion-based adhesive include acrylic resin-based emulsion adhesives, acrylic acid ester-vinyl acetate copolymer-based emulsion adhesives, vinyl acetate-based emulsion adhesives, urethane resin-based emulsion adhesives, and epoxy resin-based emulsion adhesives. Examples include polyester emulsion adhesives.
These adhesives may be used alone or in combination of two or more.

<Embossed base material>
From the viewpoint of designing the pressure-sensitive adhesive sheet satisfying the requirement (I), the base material of the pressure-sensitive adhesive sheet according to one aspect of the present invention is preferably an embossed base material having an uneven surface in which recesses and protrusions are present.
As the material for forming the embossed base material, resin material, paper material, metal material, or two kinds thereof are used from the viewpoint of easy formation of the uneven surface and good shape retention of the concave portion and the convex portion. It is preferable that the material is composed of a composite material obtained by laminating the above.

As the resin material, a resin sheet or film formed of a thermoplastic resin is preferable.
Examples of the thermoplastic resin include polyolefin resins such as polyethylene resin and polypropylene resin; polyester resins such as polyethylene terephthalate resin and polybutylene terephthalate resin; acetate resins; polystyrene resins; vinyl chloride resins; and these. Examples thereof include a mixed resin obtained by mixing two or more kinds of resins.
In one aspect of the present invention, the resin base material is preferably a resin or sheet formed of one or more thermoplastic resins selected from polyolefin-based resins, polyester-based resins, and vinyl chloride-based resins.

Examples of the paper material include high-quality paper, art paper, coated paper, glassine paper and the like.
Examples of the metal constituting the metal material include aluminum, copper, silver, gold, iron, and an alloy obtained by mixing two or more kinds of these metals.

Further, as the composite material, for example, a laminated paper in which the surface of a paper material is laminated with the above-mentioned thermoplastic resin, or a metal vapor-deposited resin sheet in which a vapor-deposited film made of a metal constituting the above-mentioned metal material is laminated on the surface of the resin sheet. And so on.

The recesses and protrusions of the embossed base material can be formed by embossing a flat material made of the above-mentioned forming material and having a flat surface.
As a method of embossing, for example, a flat material formed in a sheet shape is passed through an embossed roll, a drum having a satin finish or a matte surface, an embossed belt, or the like to transfer unevenness, and embossing. Examples thereof include a method in which a release paper having a pattern and having irregularities is heated and pressed on a flat material formed in a sheet shape to be transferred.

The cross-sectional shape of the concave portion and the convex portion when the embossed base material is cut in the thickness direction is usually a rectangle, but may be a polygon such as a triangle or a trapezoid, or a semicircular or semi-elliptical diameter.
Further, the cross-sectional shape of the concave portion and the convex portion may be a fixed shape as described above or an irregular shape.

FIG. 7 is a schematic cross-sectional view of the pressure-sensitive adhesive sheet obtained by cutting the pressure-sensitive adhesive sheet having an embossed base material, which is one aspect of the present invention, on a surface capable of distinguishing recesses and protrusions existing on the uneven surface.
In the pressure-sensitive adhesive sheet having an embossed base material, the sticking surface 21 of the pressure-sensitive adhesive layer 20 may be flat as in the pressure-sensitive adhesive sheet 3a shown in FIG. 7 (a).

Further, as shown in the pressure-sensitive adhesive sheet 3b shown in FIG. 7B, when the positions of the concave and convex portions in the horizontal direction of both the sticking surface 21 of the pressure-sensitive adhesive layer 20 and the uneven surface 11b of the embossed base material 10B are compared. , The positions of the concave portions and the convex portions in the horizontal direction are likely to be substantially the same.
That is, in the place where the concave portion 16 exists on the uneven surface 11b, the concave portion 26 is likely to be formed on the sticking surface 21 of the adhesive layer vertically above the concave portion 16. On the other hand, in the place where the convex portion 17 exists on the uneven surface 11b, the convex portion 27 is likely to be formed on the sticking surface 21 of the pressure-sensitive adhesive layer vertically above the convex portion 17.
Therefore, the pressure-sensitive adhesive sheet according to one aspect of the present invention has a configuration in which the concave portion 26 and the convex portion 27 are present on the sticking surface 21 of the pressure-sensitive adhesive layer 20, as in the pressure-sensitive adhesive sheet 3b shown in FIG. 7 (b). May be good.

The embossed base material used in one aspect of the present invention may have an uneven surface having concave portions and convex portions on only one side, and the embossed base material contained in the adhesive sheet 3c shown in FIG. 7 (c). As in 10B, the surface on the side opposite to the side on which the pressure-sensitive adhesive layer 20 is laminated may also have the concave portion 16'and the convex portion 17'.
When the embossed base material 10B contained in the adhesive sheet 3c of FIG. 7 (c) is formed by contacting a roll having an embossed pattern on a flat surface such as a resin material, FIG. 7 (c) shows. As shown, a convex portion 17'is formed on the surface 11b'on the side opposite to the position where the concave portion 16 is formed on the uneven surface 11b, and the position opposite to the position where the convex portion 17 is formed on the uneven surface 11b. A recess 16'is formed on the side surface 11b'.

In the cross section of the embossed base material used in one aspect of the present invention when cut in the thickness direction, the average height difference (H1) between the concave portion and the convex portion existing on the uneven surface is preferably 5 to 200 μm. It is preferably 10 to 150 μm, more preferably 15 to 100 μm, and even more preferably 20 to 80 μm.

The thickness (L1) of the embossed base material is preferably 10 to 1000 μm, more preferably 20 to 500 μm, and even more preferably 30 to 300 μm.
In the present specification, the above-mentioned "thickness of the embossed base material (L1)" means the maximum distance between both sides of the embossed base material, and corresponds to the length of "L1" shown in FIG.

The ratio of the average height difference (H1) when the thickness (L1) of the embossed base material is 100 is preferably 10 to 98, more preferably 20 to 95, still more preferably 30 to 90, and even more preferably. It is 40 to 85.

In the pressure-sensitive adhesive sheet having the embossed base material of one aspect of the present invention, the thickness (L2) of the pressure-sensitive adhesive layer laminated on the uneven surface of the embossed base material is preferably 20 to 500 μm, more preferably 30 to 450 μm, and further. It is preferably 50 to 400 μm.
In the present specification, the above-mentioned "thickness of the pressure-sensitive adhesive layer (L2)" means the maximum distance between both sides of the pressure-sensitive adhesive layer, and corresponds to, for example, the length of "L2" shown in FIG. To do.

In the pressure-sensitive adhesive sheet having the embossed base material of one aspect of the present invention, the ratio of the average height difference (H1) between the concave portion and the convex portion existing on the uneven surface of the embossed base material and the thickness (L2) of the pressure-sensitive adhesive layer [ (H1) / (L2)] is preferably 1/3 to 8/1, more preferably 1/2 to 6/1, still more preferably 1/1, from the viewpoint of forming an adhesive sheet satisfying the requirement (I). ~ 4/1.

When the embossed base material used in one aspect of the present invention is observed from the uneven surface side, the planar shape of the concave and convex portions existing on the uneven surface may be a polygon such as a triangle or a quadrangle, or a fixed shape such as an ellipse. It may be irregular, but it is preferable from the viewpoint of forming an adhesive sheet that satisfies the requirement (I).
When there are a plurality of recesses existing on the uneven surface, the planar shapes of the plurality of recesses may all have substantially the same shape, or may have two or more different shapes. The same applies to the shape of the plurality of convex portions when there are a plurality of convex portions.

The embossed base material used in one aspect of the present invention has a plurality of recesses in which the longitudinal directions of each shape when viewed in a plan view are arranged along a predetermined direction (q) from the viewpoint of forming an adhesive sheet satisfying the requirement (I). It has a concave-convex surface in which at least a concave group (α1) composed of the concave portions (α1) or a convex portion group (α2) composed of a plurality of convex portions arranged along a predetermined direction (q) in the longitudinal direction of each shape when viewed in a plan view is present. It is preferable that it has an uneven surface in which both the concave portion group (α1) and the convex portion group (α2) are present.

The adhesive force when the pressure-sensitive adhesive sheet having the embossed base material according to one aspect of the present invention is peeled off along the direction (p) which is the arrangement direction of the concave portion group (α1) and / or the convex portion group (α2) is determined. It becomes smaller or larger than when it is peeled off in other directions.
That is, by using an embossed base material having an uneven surface in which the concave group (α1) and / or the convex group (α2) is present, it is easy to obtain an adhesive sheet satisfying the requirement (I).
The difference in whether the adhesive force when peeled along the direction (p) is smaller or larger than when peeled along the other direction is the recess group (α1) and / or This is due to the difference in the shape and formation position of the concave or convex portions constituting the convex portion group (α2).

In the present specification, the "longitudinal direction" refers to a direction in which the long side of a rectangle having the minimum area circumscribing each shape when a concave portion or a convex portion is viewed in a plan view (hereinafter, also referred to as "circumscribed rectangle") faces.
For example, in the embossed base material 101B shown in FIG. 8, the shapes of the plurality of concave portions 161 and the plurality of convex portions 171 existing on the concave-convex surface 111b are each rectangular and coincide with the above-mentioned circumscribed rectangle. Therefore, since the directions in which the long sides of the circumscribed rectangle face are the directions (q1) and (q2), the longitudinal directions of the plurality of concave portions 161 and the plurality of convex portions 171 are also directions (q1) and (q2).

Further, in the embossed base material 102B shown in FIG. 9, the shapes of the plurality of concave portions 162 and the plurality of convex portions 172 existing on the uneven surface 112b each have a waveform, but the long side of the circumscribed rectangle circumscribing the waveform. Are the directions (q1) and (q2).
Therefore, the longitudinal directions of the plurality of concave portions 162 and the plurality of convex portions 172 are the directions (q1) and (q2).

In the present invention, the longitudinal directions of the respective shapes when the concave portion or the convex portion is viewed in a plan view have angles formed by each other as shown in the "direction (q1)" and "direction (q2)" shown in FIGS. Includes both of the two opposite directions of 180 °.
In the present invention, the two opposite directions (q1) and (q2) in which the angles formed by each other are 180 ° are collectively referred to as “direction (q)”.
Therefore, in determining whether or not the concave or convex portions are arranged along the predetermined direction (q), the longitudinal direction of each shape when the concave or convex portions are viewed in a plan view is the predetermined direction (q). ) (It shall be judged by whether or not it is along the direction (q1) and (q2)).

It should be noted that the determination as to whether or not the longitudinal direction of each shape is along the direction (q) is that the angle formed by the concave or convex portion to be formed with respect to the longitudinal direction (q) of each shape is 0 to 40 °. Judge by whether or not.
Further, the method for specifying the direction (q) is selected so as to include as many concave or convex portions as possible so that the angle formed by each shape with respect to the longitudinal direction is 0 to 40 °.

For example, when the shape of the concave portion and the convex portion is square, there are two types of "longitudinal direction" of the square in the vertical direction and the horizontal direction.
On the other hand, for example, when the shape of the concave portion and the convex portion is a circle (a circle having an aspect ratio of 1), there are two types of "longitudinal direction", that is, the vertical direction and the horizontal direction of the square circumscribing the circle. The "square circumscribing a circle" can be selected infinitely.
As described above, for the concave portion and the convex portion in which the circumscribed rectangle (square) of each shape for specifying the longitudinal direction can be selected infinitely, the "longitudinal direction" cannot be specified as one by itself.

On the uneven surface 111b of the embossed base material 101B shown in FIG. 8, a plurality of concave portions 161 and a plurality of convex portions 171 are arranged along the directions (q1) and (q2) as described above.
Therefore, the plurality of recesses 161 correspond to the above-mentioned "plurality of recesses in which the longitudinal direction of each shape when viewed in a plan view is arranged along a predetermined direction (q)", and one "recess group (α1)). It belongs to.
Further, the plurality of convex portions 171 correspond to the above-mentioned "plurality of convex portions in which the longitudinal direction of each shape when viewed in a plan view is arranged along a predetermined direction (q)", and one "convex portion group". It belongs to (α2) ”.

Further, also on the uneven surface 112b of the embossed base material 102B shown in FIG. 9, the plurality of concave portions 162 and the plurality of convex portions 172 are arranged along the directions (q1) and (q2) as described above. ..
Therefore, the plurality of recesses 162 correspond to the above-mentioned "plurality of recesses in which the longitudinal direction of each shape when viewed in a plan view is arranged along a predetermined direction (q)", and one "recess group (α1)). It belongs to.
Further, the plurality of convex portions 172 correspond to the above-mentioned "plurality of convex portions in which the longitudinal direction of each shape when viewed in a plan view is arranged along a predetermined direction (q)", and one "convex portion group". It belongs to (α2) ”.

Here, from the viewpoint of forming an adhesive sheet satisfying the requirement (I), the recess group (α1) composed of a plurality of recesses existing on the uneven surface of the embossed base material may satisfy the following requirement (1-1). It is preferable that the following requirement (1-2) is satisfied.
-Requirement (1-1): When the uneven surface is viewed in a plan view, the area ratio to 100% of the total area of the concave portions existing on the uneven surface is 60% or more (preferably 70% or more, more preferably 80% or more). More preferably, there is one group of recesses (α1) composed of a plurality of recesses (90% or more).
-Requirement (1-2): Only one group of recesses (α1) exists on the uneven surface.

As specified in the requirement (1-1), the presence of a huge recess group (α1) composed of a large number of recesses makes it easier to develop the anisotropic adhesiveness of the adhesive sheet, and the requirement (I) is satisfied. Easy to fill with adhesive sheet.
The requirement (1-2) is defined as "there is a group of recesses (α1) composed of all the recesses existing on the uneven surface", in other words, "the recesses specified in the requirement (1-1)". The area ratio of the plurality of recesses forming the group (α1) is 100% with respect to the total area of the recesses existing on the uneven surface. "

Further, from the same viewpoint as above, it is also preferable that the recess group (α1) satisfies the following requirement (1-3).
-Requirement (1-3): A plurality of recesses constituting the recess group (α1) existing on the uneven surface intersect with the end portion of the concave-convex surface.

The edge of the uneven surface specified in the requirement (1-3) refers to the outer edge of the uneven surface when the embossed base material is viewed in a plan view. For example, the embossed base material 101B of FIG. 8 refers to the four sides of the rectangle constituting the uneven surface 111b, and the embossed base material 102B of FIG. 9 refers to the four sides of the rectangle forming the uneven surface 112b.

In the embossed base material 101B shown in FIG. 8, the plurality of recesses 161 existing on the concave-convex surface 111b are all two rectangular vertical sides (ends of the concave-convex surface) constituting the concave-convex surface 111b when viewed in a plan view. ) Crosses.
Therefore, the embossed base material 101B shown in FIG. 8 satisfies the requirement (1-3).
Similarly, the embossed base material 102B shown in FIG. 9 also satisfies the requirement (1-3).

Further, from the viewpoint of forming an adhesive sheet satisfying the requirement (I), the convex portion group (α2) composed of a plurality of convex portions existing on the uneven surface of the embossed base material satisfies the following requirement (2-1). Is preferable, and it is more preferable that the following requirement (2-2) is satisfied.
-Requirement (2-1): When the uneven surface is viewed in a plan view, the area ratio of the convex portion existing on the uneven surface to 100% of the total area is 60% or more (preferably 70% or more, more preferably 80% or more). , More preferably 90% or more), there is one group of convex portions (α2) composed of a plurality of convex portions.
-Requirement (2-2): Only one group of convex portions (α2) exists on the uneven surface.

As specified in the requirement (2-1), the presence of a huge convex portion group (α2) composed of a large number of convex portions makes it easier to develop the anisotropic adhesiveness of the adhesive sheet, and the requirement (I). ) Is easy to use as an adhesive sheet.
The requirement (2-2) is defined by "there is a convex group (α2) composed of all the convex portions existing on the uneven surface", in other words, "the requirement (2-1)". The area ratio of the plurality of convex portions constituting the convex portion group (α2) is 100% with respect to the total area of the convex portions existing on the uneven surface. "

In the embossed base material used in one aspect of the present invention, when a plurality of recesses are present on the uneven surface, the widths of the plurality of recesses may be substantially the same or different from each other.
When the widths of the plurality of recesses are substantially the same, the average width of the plurality of recesses is preferably 5 to 2000 μm, more preferably 20 to 1500 μm, still more preferably 50 to 1000 μm, still more preferably 100 to 100. It is 800 μm.

In the embossed base material used in one aspect of the present invention, when a plurality of convex portions are present on the uneven surface, the widths of the plurality of convex portions may be substantially the same or different from each other.
When the widths of the plurality of convex portions are substantially the same, the average width of the plurality of convex portions is preferably 1 to 500 μm, more preferably 5 to 400 μm, still more preferably 10 to 300 μm, and even more preferably. It is 20 to 200 μm.

The ratio of the average width of the concave portion to the average width of the convex portion [concave / convex portion] present in the embossed base material used in one aspect of the present invention is preferably 1/20 to 20/1. , More preferably 1/15 to 15/1, and even more preferably 1/10 to 10/1.

Further, in the embossed base material used in one aspect of the present invention, the average of the total widths of the adjacent set of concave portions and convex portions is preferably 10 to 2000 μm, more preferably 50 to 1500 μm, and further preferably 100 to 100. It is 1000 μm.

The "width of the concave portion" and the "width of the convex portion" mean that the shapes of the concave portion and the convex portion when viewed in a plan view are substantially parallel to each other, as in the concave portion 161 and the convex portion 171 shown in FIG. When formed from straight lines (edges), it refers to the distance between these two substantially parallel straight lines.
That is, the width of the concave portion 161 shown in FIG. 8 is “d1”, and the width of the convex portion 171 corresponds to “d2”.

Further, as in the case of the convex portion 172 shown in FIG. 9, when the shapes of the concave portion and the convex portion are curved and the widths of the concave portion or the convex portion are substantially the same, the shape of the concave portion or the convex portion when viewed in a plan view is formed. The distance _{from the point (t 1} ) to the point (t ₂ ) when a _{perpendicular line is drawn to the intersection (t 2} ) with another edge with respect to the tangential direction at an arbitrary point (t _{1) on the edge.} Point to.
That is, the width of the convex portion 172 shown in FIG. 9 is “d2”.
The recess 162 shown in FIG. 9 has a non-uniform width and cannot be specified.

<Adhesive layer>
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and for example, acrylic pressure-sensitive adhesive, rubber-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, urethane-based pressure-sensitive adhesive, vinyl ether-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, and polyolefin-based pressure-sensitive adhesive. Adhesives and the like can be mentioned.
These pressure-sensitive adhesives may be used alone or in combination of two or more.

In addition, the pressure-sensitive adhesive may further contain an additive for a pressure-sensitive adhesive as long as the effects of the present invention are not impaired.
Such additives for adhesives are appropriately selected depending on the intended use, and are, for example, cross-linking agents, tackifier resins, softeners (plasticizers), ultraviolet absorbers, antioxidants, rust inhibitors, pigments. , Dyes and the like.

The pressure-sensitive adhesive may contain a cross-linking agent from the viewpoint of improving the adhesive strength of the pressure-sensitive adhesive layer to be formed.
Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and metal chelate-based cross-linking agents.

Further, the pressure-sensitive adhesive may contain a pressure-imparting resin from the viewpoint of improving the adhesive strength of the formed pressure-sensitive adhesive layer according to the type of the pressure-sensitive adhesive resin used.
As the tackifying resin, for example, C5-based petroleum obtained by copolymerizing C5 distillates such as rosin-based resin, terpene-based resin, penten, isoprene, piperin, and 1.3-pentaziene produced by thermal decomposition of petroleum naphtha. Examples include C9-based petroleum resins obtained by copolymerizing C9 distillates such as resins, inden produced by thermal decomposition of petroleum naphtha, vinyl toluene, α-methylstyrene, and β-methylstyrene, and hydrides thereof. Be done.

In the pressure-sensitive adhesive sheet of one aspect of the present invention, the thickness of the pressure-sensitive adhesive layer is preferably 20 to 1000 μm, but as described above, it is preferable to appropriately adjust the thickness according to the type of the base material used.

<Release material>
Examples of the release material used in the present invention include a release sheet that has been subjected to double-sided release treatment, a release sheet that has been subjected to single-sided release treatment, and the like, in which a release agent is applied on the surface of the base material for the release material. ..

Examples of the base material for the release material include paper base materials such as glassin paper, coated paper, and high-quality paper, laminated paper obtained by laminating a thermoplastic resin such as polyethylene on these paper base materials, polyethylene terephthalate resin, and polybutylene terephthalate. Examples thereof include a polyester resin film such as a resin and a polyethylene naphthalate resin, and a plastic film such as a polyolefin resin film such as a polypropylene resin and a polyethylene resin.
Examples of the peelable component contained in 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. Be done.

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.

<Manufacturing method of adhesive sheet>
As the method for producing the pressure-sensitive adhesive sheet according to one aspect of the present invention, it is preferable to appropriately select it according to the type of the base material used.
For example, as a method for manufacturing the pressure-sensitive adhesive sheet 1b shown in FIG. 1 (b), the following directions (i) or (ii) can be mentioned.
Method (i): A pressure-sensitive adhesive, which is a material for forming a pressure-sensitive adhesive layer, is applied onto the uneven surface of the base material to form a coating film, and the coating film is dried to form a pressure-sensitive adhesive layer. A release material is laminated on the pressure-sensitive adhesive layer.
Method (ii): A pressure-sensitive adhesive, which is a material for forming a pressure-sensitive adhesive layer, is applied onto the peel-processed surface of the release material to form a coating film, and the coating film is dried to form a pressure-sensitive adhesive layer. A base material is laminated on the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive to be used is a known coating of an organic solvent such as toluene, ethyl acetate, or methyl ethyl ketone or water in the form of a solution of the pressure-sensitive adhesive on the uneven surface of the base material or the peeling surface of the release material. It is preferable to apply by a method to form a coating film.
The concentration of the active ingredient (solid content) in the pressure-sensitive adhesive solution is preferably 10 to 80% by mass, more preferably 25 to 70% by mass, and further preferably 45 to 65% by mass.

Examples of the method for applying the adhesive solution include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, and a gravure coating method.
In order to prevent the solvent and low boiling point components from remaining in the formed pressure-sensitive adhesive layer, it is preferable to dry the formed coating film to remove the solvent and low boiling point components.

As a method for producing the pressure-sensitive adhesive sheet using the fiber base material, the method (i) described above is preferable from the viewpoint of obtaining the pressure-sensitive adhesive sheet satisfying the requirement (I).
When a fiber base material is used, as described above, before forming the pressure-sensitive adhesive layer, a plurality of fibers existing on the uneven surface of the fiber base material are blown along a predetermined direction (x) using a brush or a brush. And brushing is preferable.
Further, it is preferable to form the pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive, which is a material for forming the pressure-sensitive adhesive layer, on the uneven surface of the fiber base material along a predetermined one direction (x).

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
The methods for measuring various physical property values related to the base material are as follows.

<Thickness of support part of fiber base material, thickness of embossed base material, thickness of adhesive layer>
Measurement was performed using a constant pressure thickness measuring device (manufactured by Teclock Co., Ltd., product name "PG-02") in accordance with JIS K7130.
Regarding the thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet using the fiber base material as the base material, the thickness of the pressure-sensitive adhesive sheet (total thickness of the support portion of the base material and the pressure-sensitive adhesive layer) measured by the above method. The difference between the thickness of the support portion of the base material and the thickness of the support portion of the base material was taken as the thickness of the target pressure-sensitive adhesive layer.

<Average length, average thickness, average aspect ratio of fibers existing on the surface (α) of the fiber base material>
Using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, product name "S-4700"), none of the multiple fibers existing on the surface (α) of each fiber base material before applying the adhesive. The 10 fibers extracted at random were observed, and the "length", "thickness", and "aspect ratio (= length / thickness)" of each were measured.
Then, the average value of each of the length, thickness, and aspect value of the 10 fibers was defined as the "average length", "average thickness", and "average aspect ratio" of the plurality of target fibers.

<Density of fibers existing on the surface (α) of the fiber base material>
Using a digital microscope (manufactured by Keyence, product name "Digital Microscope VHX-5000", high-resolution zoom lens VHX-ZST 100x), arbitrarily on the surface (α) of each fiber substrate before applying the adhesive. The selected region surrounded by a square with a side of 4 mm was observed with the digital microscope, and a digital image of the region was acquired by the depth composition function.
Then, the number of fibers existing in the region was counted from the acquired digital image.
Five regions were selected, and the average value of the number of fibers confirmed in each region was taken as the fiber density (unit: fiber / mm ² ) of the target base material.

<Observation of multiple fibers existing inside the pressure-sensitive adhesive layer when using a fiber base material>
A digital microscope (manufactured by KEYENCE, product name "Digital Microscope VHX-5000", high-resolution zoom lens) covers the area surrounded by a square with a side of 4 mm, which is arbitrarily selected from the surface to be attached to the adherend of the adhesive layer. VHX-ZST 100 times) was used for observation.

<Linear distance between the fixed end of the fiber and the farthest part, the average height of the fiber>
When the presence of fibers oriented along one direction (p) is confirmed, the adhesive is cut perpendicular to the sticking surface at an arbitrary position along the one direction (p) of the sticking surface. An image was acquired when the cross section of the sheet was observed using a scanning electron microscope (manufactured by Hitachi High-Technologies Corporation, product name "S-4700").
Then, the "straight line distance between the fixed end and the farthest part" and the "fiber height" were measured for 10 randomly selected fibers that could be confirmed from the acquired image, and the average value was calculated. ..

Example 1
As the fiber base material, the brushed base material shown below was used.
(Details of brushed base material)
-A polyester cloth (84 dtx / 48f) that has been brushed and has a surface (α) in which a plurality of brushed fibers (polyester fibers) are present.
-Thickness of polyester cloth (thickness of support part of brushed base material) = 650 μm.
-Average aspect ratio of raised fibers = 42, average length of raised fibers = 588 μm, average thickness of raised fibers = 14 μm.
・ Density of brushed fibers = 185 fibers / mm ²

Using an applicator, an acrylic adhesive (manufactured by Lintec Corporation, trade name "PAT1") is applied to the surface (α) of the brushed base material on which a plurality of brushed fibers are present, and 50% or more of the brushed fibers are applied. Was applied along one direction (p) (horizontal direction of the pressure-sensitive adhesive sheet to be produced) in which the pressure was inclined, and dried to form a pressure-sensitive adhesive layer having a thickness of 190 μm.
When the exposed surface of the formed pressure-sensitive adhesive layer is viewed in a plan view, 90% or more of the plurality of raised fibers existing on the surface (α) of the raised base material is along one direction (p). It was confirmed that it corresponds to the aligned fibers.
Further, various measured values of the fibers confirmed when observing the cross section of the pressure-sensitive adhesive sheet cut perpendicularly to the sticking surface at an arbitrary position along one direction (p) are as follows.

-Average value of the linear distance between the fixed end and the farthest part of the fiber = 380 μm
-Ratio of the average value of the straight line distance between the fixed end and the farthest part of the fiber and the thickness of the pressure-sensitive adhesive layer [average value of the straight line distance / thickness of the pressure-sensitive adhesive layer] = 2.0
-Average height of fibers based on the surface (α) = 185 μm
-Ratio of average fiber height / thickness of adhesive layer = 0.97
-Ratio of fibers in which the ratio of the height of fibers to the thickness of the pressure-sensitive adhesive layer with respect to the surface (α) is 0.5 or more = the total number of fibers existing on the surface (α) (100%) 90% or more.

Then, the exposed surface of the formed pressure-sensitive adhesive layer and the peel-treated surface of the release sheet (manufactured by Lintec Corporation, trade name "SP-PET381031") were attached to prepare the pressure-sensitive adhesive sheet (a). ..

Example 2
As the fiber base material, the following flocked base material was used.
(Details of flocked base material)
-A flocked base material having a surface (α) in which a flocked treatment is applied on one surface of a polyethylene terephthalate (PET) film which is a support portion and a plurality of flocked fibers composed of rayon fibers are present.
-PET film thickness (thickness of the support part of the flocked base material) = 75 μm.
-Average aspect ratio of flocked fibers = 21.4, average length of flocked base material = 300 μm, average thickness of flocked base material = 14 μm.
-Density of flocked fibers = 728 fibers / mm ² .

Using an applicator, 50% of an acrylic emulsion type adhesive (manufactured by Lintec Corporation, trade name "PC-N") is applied on the surface (α) of the above flocked base material on which a plurality of flocked fibers are present. The above flocked fibers were applied along the inclined direction (p) (horizontal direction of the pressure-sensitive adhesive sheet to be produced) and dried to form a pressure-sensitive adhesive layer having a thickness of 60 μm.
When the exposed surface of the formed pressure-sensitive adhesive layer is viewed in a plan view, 90% or more of the plurality of flocked fibers existing on the surface (α) of the flocked base material is along one direction (p). It was confirmed that it corresponds to the aligned fibers.
Further, various measured values of the fibers confirmed when observing the cross section of the pressure-sensitive adhesive sheet cut perpendicularly to the sticking surface at an arbitrary position along one direction (p) are as follows.

-Average value of the straight line distance between the fixed end and the farthest part of the fiber = 280 μm
-Ratio of the average value of the linear distance between the fixed end and the farthest part of the fiber and the thickness of the pressure-sensitive adhesive layer [average value of the straight-line distance / thickness of the pressure-sensitive adhesive layer] = 4.7
-Average height of fibers based on the surface (α) = 58 μm
-Ratio of average fiber height / thickness of adhesive layer = 0.97
-The ratio of the height of the fibers to the thickness of the pressure-sensitive adhesive layer based on the surface (α) is 0.5 or more = the total number of fibers existing on the surface (α) (100%). On the other hand, 90% or more.

Then, the exposed surface of the formed pressure-sensitive adhesive layer and the peel-treated surface of the release sheet (manufactured by Lintec Corporation, trade name "SP-PET38131") were attached to prepare the pressure-sensitive adhesive sheet (b). ..

Examples 3-4
In Example 3, similarly to the embossed base material 101B shown in FIG. 8, an embossed base material (1) having an uneven surface having a plurality of concave portions and a plurality of convex portions was used.
Further, in Example 4, similarly to the embossed base material 102B shown in FIG. 9, an embossed base material (2) having an uneven surface having a plurality of concave portions and a plurality of convex portions was used.
Both the embossed base materials (1) and (2) were obtained by embossing a polyethylene terephthalate (PET) film.
Details of the embossed base materials (1) and (2) are as shown in Table 1 below.

Acrylic adhesive (manufactured by Lintec Corporation, trade name "PK") is applied to the uneven surfaces of the embossed base materials (1) and (2) in Table 1 in the flow direction (horizontal direction of the heteroadhesive sheet to be produced). ) And dried to form an adhesive layer having a thickness of 20 μm.
Then, the exposed surface of the formed pressure-sensitive adhesive layer and the peel-treated surface of the release sheet (manufactured by Lintec Corporation, trade name "SP-PET381031") are overlapped and sufficiently pressure-bonded to form the pressure-sensitive adhesive sheet (c) and the pressure-sensitive adhesive sheet (c). (D) were prepared respectively.

Comparative Example 1
As the base material, a flat base material having a flat surface and having a thickness of 50 μm (manufactured by Toray Industries, Inc., trade name “Lumilar T60”) was used.
An adhesive sheet to be produced in one direction (p) (manufactured by Lintec Corporation, trade name "PAT1") using an acrylic adhesive (manufactured by Lintec Corporation, trade name "PAT1") on a flat surface without unevenness of the above-mentioned flat base material. It was applied in the lateral direction of) and dried to form a pressure-sensitive adhesive layer having a thickness of 60 μm.
Then, the exposed surface of the formed pressure-sensitive adhesive layer and the peel-processed surface of the release sheet (manufactured by Lintec Corporation, trade name "SP-PET381031") were attached to prepare the pressure-sensitive adhesive sheet (e). ..

Comparative Example 2
A pressure-sensitive adhesive sheet (f) was produced in the same manner as in Comparative Example 1 except that an acrylic emulsion-type pressure-sensitive adhesive (manufactured by Lintec Corporation, trade name “PC-N”) was used as the pressure-sensitive adhesive.

The adhesive strengths (Nx) and (Ny) of the adhesive sheets (a) to (f) produced in Examples and Comparative Examples were measured by the following procedure. The results of the measured adhesive strength are shown in Table 2.

(1) Measurement of Adhesive Strength (Nx) The adhesive sheets (a) to (f) produced in Examples and Comparative Examples were subjected to SUS304 (# 600 polished surface) in an atmosphere of 23 ° C. and 50% RH (relative humidity). ), A 2 kg rubber roller was reciprocated once along the lateral direction of the adhesive sheet, and the sheet was allowed to stand for 20 minutes.
Then, using a universal tensile tester (manufactured by Orientec Co., Ltd., trade name "TENSILON / UTM-4-100"), the peeling angle is as shown in FIG. 6A in accordance with JIS Z0237: 2000. The adhesive strength (Nx) (N / 25 mm) when peeled from the adherend was measured along the direction (x) shown in Table 2 at 180 ° and a peeling speed of 300 mm / min.
The adhesive strength (Nx) was measured three times, and the average value thereof was taken as the "adhesive strength (Nx)" of the target adhesive sheet, and the values are shown in Table 2.

(2) Measurement of Adhesive Strength (Ny) The adhesive sheets (a) to (f) produced in Examples and Comparative Examples were subjected to SUS304 (# 600 polished surface) in an atmosphere of 23 ° C. and 50% RH (relative humidity). ), A 2 kg rubber roller was reciprocated along the lateral direction of the adhesive sheet to attach it, and the sheet was allowed to stand for 20 minutes.
Then, using a universal tensile tester (manufactured by Orientec Co., Ltd., trade name "TENSILON / UTM-4-100"), in accordance with JIS Z0237: 2000, at a peeling angle of 180 ° and a peeling speed of 300 mm / min. The adhesive force (Ny) (N / 25 mm) when the angle θ ° formed with the direction (x) was peeled from the adherend along the direction (y) shown in Table 2 was measured.
The adhesive strength (Ny) was measured three times, and the average value thereof was taken as the "adhesive strength (Ny)" of the target adhesive sheet, and the values are shown in Table 2.

(3) Degree of change in adhesive strength Based on the values of adhesive strength (Nx) and (Ny) measured in (1) and (2) above, the adhesive strength (Nx) and (Ny) can be determined from the following formula (F1). The degree of change in adhesive strength with respect to the average value was calculated. The results are shown in Table 2.
Formula (F1): Degree of change in adhesive strength = | Ny-Nx | / ((Ny + Nx) / 2) x 100

From Table 1, the adhesive sheets (a) to (d) produced in Examples 1 to 4 had different adhesive strengths depending on the peeling direction, and the degree of change in adhesive strength was 10 or more.
On the other hand, the adhesive sheets (e) to (f) produced in Comparative Examples 1 and 2 show a phenomenon in which the adhesive force greatly changes depending on the peeling direction, as in the adhesive sheets (a) to (d). There wasn't.

1, 1a, 1b, 1c, 2, 3a, 3b, 3c Adhesive sheet 10 base material 10A Fiber base material 10B, 101B, 102B Embossed base material 11, 11', 11b, 111b, 112b Concavo-convex surface 11a Surface (α)
12, 12a, 12b Fiber 121a, 121b Fixed end 122a, 122b End 123b Farthest 124b Top 16, 16', 161, 162 Concave 17, 17', 171, 172 Convex 20, 20'Adhesive layer 21 Sticking surface 26 Concave part 27 Convex part 30, 30'Release material 500 Adhesive

Claims (5)

A substrate having an uneven surface, and a pressure-sensitive adhesive layer laminated directly on the uneven surface of the base material, it meets the following requirements (I), wherein the substrate, an uneven surface having a plurality of fibers are present An adhesive sheet that is a fiber base material to have.
Requirement (I): After the adhesive sheet is attached to an adherend, the adhesive sheet is peeled and measured at a peeling angle of 180 ° along an arbitrarily selected x direction in accordance with JIS Z0237: 2000. Adhesive force (Nx) [N / 25 mm], adhesive force (Ny) [N / 25 mm] of the adhesive sheet measured by peeling along the y direction, and the angle formed by the x direction and the y direction is θ (0 ° < When θ ≦ 180 °), there is at least one θ having an adhesive force change degree of 10 or more with respect to the average value of the adhesive force (Nx) and (Ny) calculated from the following formula (F1).
Formula (F1): Degree of change in adhesive strength = | Nx-Ny | / ((Nx + Ny) / 2) x 100 The adhesive according to claim 1 , wherein the fiber base material is a raised base material having a concavo-convex surface in which raised fibers are present, or a flocked base material having a concavo-convex surface in which the flocked fibers are present. Sheet. The ratio of the average height of the fibers to the thickness of the pressure-sensitive adhesive layer with respect to the surface (α), which is the surface including the fixed end to which the fibers constituting the fiber base material are fixed [the average of the fibers]. The pressure-sensitive adhesive sheet according to claim 1 or 2 , wherein the height / thickness of the pressure-sensitive adhesive layer is 0.4 to 0.99. The pressure-sensitive adhesive sheet according to claim 1, wherein the base material is an embossed base material having an uneven surface in which concave portions and convex portions are present. The pressure-sensitive adhesive sheet according to claim 4 , wherein the average height difference (H1) between the concave portion and the convex portion existing on the uneven surface is 5 to 200 μm in a cross section obtained by cutting the embossed base material in the thickness direction. ..

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