Adhesive sheet

Abstract

To provide an adhesive sheet in which fold marks are less likely to be formed at the bent portion when bonded to an adherend and folded.SOLUTION: An adhesive sheet 10 comprising at least an adhesive layer 1, wherein the adhesive layer 1 has, on the same surface 1a, a first region 11 and a second region 12, each being a single linear shape. The first region 11 and the second region 12 are parallel to each other, and the first region 11 and the second region 12 differ in physical properties. It is preferable that the first region 11 and the second region 12 differ in hardness. The first region 11 and the second region 12 may each be a straight line.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet. [Background technology]

[0002] Among optical devices such as displays, thin, flexible displays, typified by OLEDs, are constructed by laminating multiple optical films or thin-layer devices. Furthermore, devices that require flexibility, such as pressure-sensitive sensors, are constructed by laminating a pressure-sensitive member and a substrate (Patent Document 1). Liquid curing resins, pressure-sensitive adhesives, and adhesives are selected as interlayer fillers in these laminates, and pressure-sensitive adhesives and adhesives (such as pressure-sensitive adhesives) are preferably used from the viewpoints of improving workability, preventing warping due to cure shrinkage, and improving flexibility through stress dispersion.

[0003] The above-mentioned adhesives, etc., have the function of dispersing and alleviating stress generated by bending and folding, particularly in flexible members, and this function is said to be exhibited more efficiently the more flexible the adhesives, etc. (Patent Document 2), and therefore flexible adhesives, etc. are used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-159463 [Patent Document 2] Japanese Patent Publication No. 2020-109177 Summary of the Invention [Problem to be solved by the invention]

[0005] However, laminates formed by bonding adherends together using an adhesive sheet with a flexible adhesive layer have the problem that when the laminate is bent, the adhesive layer cannot withstand the bending stress of the adherend, causing the folded portion of the laminate to become concave and leaving crazes.

[0006] The present invention has been made to solve these problems, and an object of the present invention is to provide a pressure-sensitive adhesive sheet that, when attached to an adherend and folded, is less likely to leave a crease at the folded portion. [Means for solving the problem]

[0007] The present inventors have made extensive efforts to solve the above problems and have found that a specific pressure-sensitive adhesive sheet is less likely to leave a crease at the folded portion when attached to an adherend and folded. The present invention was completed based on these findings.

[0008] That is, the present invention provides a pressure-sensitive adhesive layer having, in the same plane, a first region which is a single linear region and a second region which is a single linear region parallel to the first region, The pressure-sensitive adhesive sheet has different physical properties between the first region and the second region.

[0009] The physical property is preferably hardness.

[0010] The hardness is preferably one or more selected from the group consisting of tensile strength, modulus of elasticity, Young's modulus, elongation at break, stress at break, surface hardness, swelling degree, gel fraction, hardness measured by nanoindentation method, and residual stress.

[0011] It is preferable that each of the first region and the second region is a single straight line.

[0012] In the pressure-sensitive adhesive layer, the first regions and the second regions are preferably arranged alternately in one direction of the pressure-sensitive adhesive layer.

[0013] The first region and the second region preferably extend from one end side to the other end side in a direction perpendicular to the thickness direction of the pressure-sensitive adhesive layer.

[0014] The pressure-sensitive adhesive sheet may be used by being attached to a foldable adherend, the first region being included in a region corresponding to the fold of the adherend, the second region being adjacent to both sides of the first region, and the hardness of the first region being harder than the hardness of the second region.

[0015] the pressure-sensitive adhesive sheet has a hardness of the first region greater than a hardness of the second region, The pressure-sensitive adhesive sheet may be one in which the first region and the second region are alternately positioned adjacent to each other in one direction of the pressure-sensitive adhesive layer, and the first region is located within a range of ±1 mm from the center in the one direction.

[0016] The pressure-sensitive adhesive sheet is preferably used by being stuck to an optical member.

[0017] The pressure-sensitive adhesive sheet is preferably used by being stuck to a foldable adherend. [Effects of the Invention]

[0018] When the pressure-sensitive adhesive sheet of the present invention is attached to an adherend and folded, fold marks are unlikely to form at the folded portion. [Brief explanation of the drawings]

[0019] [Figure 1] 1 shows a schematic cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 2] 1 shows a plan view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention. [Figure 3] 3 is a cross-sectional view showing the pressure-sensitive adhesive sheet shown in FIG. 2 in a folded state. [Figure 4] FIG. 2 is a plan view of a pressure-sensitive adhesive sheet according to another embodiment of the present invention. [Figure 5] 5 is a cross-sectional view showing the adhesive sheet shown in FIG. 4 in a folded state. [Figure 6] FIG. 2 is a plan view showing an embodiment of a pressure-sensitive adhesive sheet in which the first region and the second region are curved. [Figure 7]FIG. 2 shows a plan view of a pressure-sensitive adhesive composition in an example. [Figure 8] 1 is a graph showing nanoindentation hardness measured in the vicinity of a first region and a second region in an example. DETAILED DESCRIPTION OF THE INVENTION

[0020] [Adhesive sheet] In this specification, "adhesion" refers to the property of two surfaces adhering to each other in response to external pressure (e.g., minute pressure) based on the cohesive force of the chemical structure of the composition, and allowing separation if necessary. In contrast, "adhesion" refers to the property of two surfaces being firmly joined together by a chemical reaction (curing) of the composition to produce a cured product, without the intention of separation.

[0021] In addition, in this specification, the form of the "adhesive" is not particularly limited, and it may be a liquid at room temperature (for example, a solid (paste-like) having fluidity, an adhesive composition, etc.), or it may be a solid at room temperature. In addition, the form of the "adhesive" is not particularly limited, and it may be in the form of a sheet. In this specification, the "adhesive layer" is a sheet-like (layer-like) adhesive layer that does not have fluidity.

[0022] The pressure-sensitive adhesive sheet of the present invention comprises at least a pressure-sensitive adhesive layer having, in the same plane, a first region that is a single line and a second region that is parallel to the first region and is also a single line. The first region and the second region have different physical properties. In this specification, the pressure-sensitive adhesive layer may be referred to as the "pressure-sensitive adhesive layer of the present invention." Furthermore, "a single line" refers to a line that has no branch points.

[0023] The pressure-sensitive adhesive sheet of the present invention may be a so-called "substrate-less type" pressure-sensitive adhesive sheet that does not have a substrate (substrate layer), or may be a type of pressure-sensitive adhesive sheet that has a substrate. In this specification, a "substrate-less type" pressure-sensitive adhesive sheet may be referred to as a "substrate-less pressure-sensitive adhesive sheet," and a type of pressure-sensitive adhesive sheet that has a substrate may be referred to as a "substrate-attached pressure-sensitive adhesive sheet." Examples of the substrate-less pressure-sensitive adhesive sheet include a double-sided pressure-sensitive adhesive sheet consisting only of the pressure-sensitive adhesive layer of the present invention, and a double-sided pressure-sensitive adhesive sheet consisting of the pressure-sensitive adhesive layer of the present invention and another pressure-sensitive adhesive layer (a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer of the present invention). Examples of the substrate-attached pressure-sensitive adhesive sheet include a single-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer of the present invention on one side of the substrate, a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer of the present invention on both sides of the substrate, and a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer of the present invention on one side of the substrate and another pressure-sensitive adhesive layer on the other side. The "substrate (substrate layer)" refers to a support, and is the part that is attached to the adherend together with the pressure-sensitive adhesive layer when the pressure-sensitive adhesive sheet of the present invention is used (attached) to the adherend. The release liner that is peeled off when the pressure-sensitive adhesive sheet is used (applied) is not included in the above substrate.

[0024] The pressure-sensitive adhesive sheet of the present invention will be described below with reference to the drawings, although the pressure-sensitive adhesive sheet of the present invention is not limited to the embodiments shown in the drawings.

[0025] Figure 1 is a cross-sectional view showing a pressure-sensitive adhesive sheet according to one embodiment of the present invention. Pressure-sensitive adhesive layer 1 shown in Figure 1 is laminated on the release-treated surface of release liner 2 to form pressure-sensitive adhesive sheet 10 with a release liner.

[0026] <Adhesive layer> (First embodiment) Fig. 2 shows a plan view of a pressure-sensitive adhesive sheet (first embodiment) according to one embodiment of the present invention. The pressure-sensitive adhesive layer 1 shown in Fig. 2 has a single linear first region 11 and a single linear second region 12 formed therein, each extending perpendicularly to the thickness direction of the pressure-sensitive adhesive layer 1 (first direction D1). Furthermore, the pressure-sensitive adhesive layer 1 has, in the same plane, the first region 11, the second region 12, the first region 11, the second region 12, and the first region 11, in this order, extending in a second direction D2 perpendicular to the first direction D1. The first region 11 and the second region 12 are alternately formed in one direction (second direction D2) from a first edge E1 of the pressure-sensitive adhesive layer 1 toward a second edge E2 opposite the first edge E1. The first region 11 and the second region 12 are each continuously formed so as to extend from one end side (third edge E3) of the pressure-sensitive adhesive layer 1 to the other end side (fourth edge E4 opposite the third edge E3). In FIG. 2, the boundary between the first region 11 and the second region 13 is drawn with a solid line, but in reality, the boundary does not need to be observed visually.

[0027] The three first regions 11 and two second regions extend in the first direction D1 and are parallel to each other. Although all the first regions and second regions are parallel to each other in Fig. 2, in the pressure-sensitive adhesive layer of the present invention, it is sufficient that at least one first region and at least one second region are parallel to each other, since the pressure-sensitive adhesive layer can be folded when used.

[0028] The first region 11 and the second region 12 have different physical properties. For example, the hardness of the first region 11 is harder than the hardness of the second region 12. In other words, the first region 11 may be a hard portion that is relatively harder (than the second region 12), and the second region 12 may be a soft portion that is relatively softer (than the first region 11).

[0029] The first region 11 and the second region 12 may have the same or different widths. In FIG. 2, the two second regions 12 have the same width, but they may have different widths. In FIG. 2, the two first regions 11 located at both ends have the same width, and the width of the first region 11 located in the center is shorter than the widths of the other two first regions 11, but it may be longer or the same. The widths of all the first regions and all the second regions may be the same or different.

[0030] The center of the pressure-sensitive adhesive layer 1 in one direction (first direction D1) is the first region 11, and the two second regions 1 2 are adjacent to both sides of the central first region 11.

[0031] In the pressure-sensitive adhesive layer 1 shown in Figure 2, the total area of ​​the first regions 11 is larger than the total area of ​​the second regions 12. Furthermore, in the pressure-sensitive adhesive layer 1 shown in Figure 2, the total line width length of the first regions 11 is longer than the total line width length of the second regions 12. When the hardness of the first regions 11 is greater than the hardness of the second regions 12, the strength of the pressure-sensitive adhesive layer and pressure-sensitive adhesive sheet in such a configuration is increased. Note that the total area of ​​the first regions 11 may be smaller than the total area of ​​the second regions 12, and the total line width length of the first regions 11 may be shorter than the total line width length of the second regions 12.

[0032] An adhesive sheet having an adhesive layer as shown in Figure 2 has a first region and a second region with different physical properties, so that when bending stress is applied to one of the first region and the second region, the other can relieve the bending stress, thereby suppressing the occurrence of creases when folded.

[0033] Fig. 3 shows an example of the folded state of the pressure-sensitive adhesive sheet shown in Fig. 2. When the pressure-sensitive adhesive sheet 10 made of the pressure-sensitive adhesive layer 1 shown in Fig. 2 is folded in the middle as shown in Fig. 3, a first region 11, which is a hard region, is located in the center of the folded portion B, and second regions 12, which are soft regions, are located on both sides of the first region 11, and the folded portion B includes the second region 12 / first region 11 / second region 12. When folded in this manner, when bending stress is applied to the first region 11, the second region 12 can relieve the bending stress, and fold marks are less likely to be left when the sheet is folded. Furthermore, it is preferable that the folded portion B includes both the first region 11 and the second region 12.

[0034] Second Embodiment Figure 4 shows a plan view of a pressure-sensitive adhesive sheet according to another embodiment (second embodiment) of the present invention. The pressure-sensitive adhesive layer 1 shown in Figure 4 has one linear first region 11 and one linear second region 12 formed therein, extending in a first direction D1. The pressure-sensitive adhesive layer 1 shown in Figure 4 is similar to the pressure-sensitive adhesive layer 1 shown in Figure 2, except that the number and widths of the first regions 11 and second regions 12 are different. In the pressure-sensitive adhesive layer 1 shown in Figure 4, the first regions 11 and second regions 12 are formed in a striped pattern.

[0035] As shown in Figure 3, an adhesive sheet having an adhesive layer in which first and second regions are adjacent to each other in one direction and formed in an alternating striped pattern has alternating physical properties, so when stress is applied to one region, the stress is easily distributed to the other adjacent region, resulting in better overall strength and impact resistance for the adhesive sheet and the adherend to which the adhesive sheet is bonded.

[0036] The widths of the first region 11 and the second region 12 (the width of one region) are not particularly limited, but can each be selected, for example, within the range of 0.001 to 50 mm. The ratio of the width of the first region 11 (the width of one region) to the width of the second region 12 (the width of one region) [first region / second region] is not particularly limited, but is, for example, 0.01 to 100.

[0037] The boundary between the first region 11 and the second region 12 may or may not be clearly defined. The vicinity of the boundary between the first region 11 and the second region 12 may be a boundary region where the physical properties gradually change. The boundary region has a gradient of physical properties, and the physical properties gradually change from the physical properties of the first region 11 to the physical properties of the second region 12 along the second direction D2 from the center of the first region 11 to the center of the second region 12. Therefore, the boundary region is the region from the point where the gradient of the physical properties starts to the point where the gradient ends. When the boundary region is present, the physical properties of the first region 11 and the physical properties of the second region 12 are the physical properties of the portions other than the boundary region (for example, the central portion in the second direction D2).

[0038] 2 and 4, the hardness of the first region 11 is greater than the hardness of the second region 12. In the pressure-sensitive adhesive layer 1, the first region 11 and the second region 12 are positioned adjacent to each other alternately in one direction (second direction D2) of the pressure-sensitive adhesive layer 1. In FIG. 2, the first region 11 is at the center in the second direction D2. In FIG. 4, the first region is located within a range of ±1 mm from the center in the second direction D2. With this configuration, when the bend portion is near the center in the second direction D2, the first region 11 will be subjected to the greatest bending stress upon bending, but the shape of the pressure-sensitive adhesive layer will be more easily maintained, and the bending stress can be alleviated in the adjacent second region 12, making it possible to particularly suppress the occurrence of creases upon bending.

[0039] FIG. 5 shows an example of a folded state of the adhesive sheet shown in FIG. 4. When the adhesive sheet 10 made of the adhesive layer 1 shown in FIG. 4 is folded at its center, as shown in FIG. 5, the first region 11, which is a hard portion, and the second regions 12 on both sides of it are located near the center of the folded portion B (within a range of ±1 mm from the center), and the folded portion B includes the second region 12 / first region 11 / second region 12 / first region 11 / second region 12 / first region 11 / second region 12. The folded portion B also includes both the first region 11 and the second region 12. In the adhesive sheet 10 shown in FIG. 4, the first region 11 and the second region 12 are both narrower than those in the adhesive sheet shown in FIG. 2. Therefore, when folded as shown in FIG. 5, even if the first region 11 is not located at the center in the second direction D2, the second region 12 can relieve bending stress when bending the first region 11, and fold marks are less likely to be left. The adhesive sheet shown in FIG. 4 can also be rolled by folding at least a portion of it. Therefore, the adhesive layer 1 shown in Figure 4 can be rolled up to follow the adherend even when it is attached to a rollable adherend so that the position corresponding to the center of the folded portion is an area including the second region 12.

[0040] Furthermore, when the hardness of the first region 11 is harder than the hardness of the second region 12, the center of the adhesive layer 1 in the second direction D2 does not have to be the first region 11, and as long as the first region 11 is included in the region corresponding to the bending portion of the bendable adherend, the occurrence of creases when bending can be particularly suppressed.

[0041] 2 and 4, both first region 11 and second region 12 are formed linearly, but first region 11 and second region 12 may be linear with at least a portion curved, as long as the pressure-sensitive adhesive sheet can be bent. Furthermore, first region 11 and second region 12 may have a line width that varies at least partially along the length, as long as the pressure-sensitive adhesive layer can be bent. The maximum value of the radius of curvature of the curve is not particularly limited, but is, for example, R1000 mm or less (e.g., R greater than 0 mm and R1000 mm or less).

[0042] Furthermore, when the first region 11 and / or the second region 12 includes a curve, the first region 11 and / or the second region 12 preferably has a shape that allows a single straight line to be drawn within that region that does not contact an adjacent region. For example, in the pressure-sensitive adhesive layer 1 shown in Figure 6, the first region 11 and the second region 12 are formed in a curved shape, and a straight line L1 that does not contact an adjacent second region can be drawn within the first region 11.

[0043] In FIGS. 2 and 4 , both the first region 11 and the second region 12 extend continuously from the third edge E3 to the fourth edge E4. However, at least one of the first region 11 and the second region 12 may extend discontinuously. For example, at least one of the first region 11 and the second region 12 may be represented by a dashed line. The length and / or spacing of each dashed line may be the same or different. The spacing may be regular or irregular. At least one of the first region 11 and the second region 12 may not extend from the third edge E3 to the fourth edge E4. For example, it may extend from a region away from the third edge E3 to the fourth edge E4, or it may extend from the third edge E3 toward the fourth edge E4 but not reach the fourth edge E4, or it may extend from a region away from the third edge E3 toward the fourth edge E4 but not reach the fourth edge E4.

[0044] The respective numbers and total numbers of first regions 11 and second regions 12 in the second direction D2 are not particularly limited. For example, when first regions 11 and second regions 12 are alternately formed adjacent to one another in the second direction D2, the greater the total number, the stronger the PSA layer and PSA sheet tend to be. Furthermore, even when the adherend has multiple folded portions, the frequency corresponding to first regions 11 increases, making it less likely that creases will occur during folding. In this specification, when first regions 11 or second regions 12 are indicated by dashed lines, a group of regions extending from the third edge E3 to the fourth edge E4 is considered to be one region.

[0045] The pressure-sensitive adhesive layer 1 shown in Figures 2 and 4 is symmetrical in one direction (first direction D1 and / or second direction D2). For example, in Figures 2 and 4, the first region 11 and the second region 12 are positioned symmetrically in one direction (second direction D2). However, the pressure-sensitive adhesive layer may be asymmetrical in one direction.

[0046] 2 and 4, both ends in one direction (second direction D2) are first regions 11. When the hardness of the first regions 11 is greater than the hardness of the second regions 12, the strength of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive sheet in this configuration is increased. Note that both ends in one direction (second direction D2) do not have to be first regions 11.

[0047] In the pressure-sensitive adhesive layer 1, the first region 11 and the second region 12 may each extend over the entire thickness of the pressure-sensitive adhesive layer, or may extend over only a portion including the surface. The thicknesses of the first region 11 and the second region 12 in the pressure-sensitive adhesive layer 1 are not particularly limited, but can each be selected, for example, from within a range of 0.1 to 300 μm. The ratio of the thickness (average thickness) of the first region 11 to the thickness (average thickness) of the second region 12 [first region / second region] is also not particularly limited, but is, for example, 0.1 to 10. The thicknesses of all the first regions and all the second regions may be the same or different.

[0048] The first region 11 and the second region 12 may have different optical properties. In particular, when the pressure-sensitive adhesive sheet 10 is used to be attached to an optical member in an image display device, the pressure-sensitive adhesive sheet located on the display side is required to have high transparency, and in this case, it is preferable that the first region 11 and the second region 12 have high transparency. On the other hand, when the pressure-sensitive adhesive sheet 10 is used to be attached to an optical member in an image display device and is used on the back side of the image display device, the transparency of the first region 11 and the second region 12 may be low.

[0049] The pressure-sensitive adhesive layer 1 may have regions other than the first region 11 and the second region 12. The other regions can be arranged in any position and shape as long as the pressure-sensitive adhesive sheet can be folded. In FIGS. 2 and 4, the first region 11 and the second region 12 are alternately formed in the pressure-sensitive adhesive layer 1, and in particular, the first region 11 and the second region 12 are alternately formed adjacent to each other. Specifically, the pressure-sensitive adhesive layer 1 has a structure of [first region 11 / second region 12 / ··· / first region 11] along one direction (second direction D2). Here, when the pressure-sensitive adhesive layer has a third region as another region having physical properties different from both the first region 11 and the second region 12, the pressure-sensitive adhesive layer may have a structure of [first region / second region / third region / first region / second region / third region / ··· / first region].

[0050] The physical properties in which the first region 11 and the second region 12 differ include hardness and optical properties. Examples of hardness include tensile strength, modulus of elasticity, Young's modulus, elongation at break, stress at break, surface hardness, swelling, gel fraction, hardness measured by nanoindentation, and residual stress. Nanoindentation can be used to measure, for example, the surface of the pressure-sensitive adhesive layer 1 or the exposed surface of the pressure-sensitive adhesive layer 1 in a cross section. The hardness measured by nanoindentation is determined by continuously measuring the load and indentation depth of an indenter applied to a target surface during loading and unloading, and then deriving the resulting load-indentation depth curve. The hardness can be adjusted by known or conventional methods. Specifically, the hardness of each region of the pressure-sensitive adhesive layer can be controlled by adjusting the amount of a curing agent, cross-linking agent, cross-linkable compound such as a polyfunctional monomer, or polymerization initiator used in preparing the resin constituting the pressure-sensitive adhesive layer 1. The different physical properties may be of only one type or of two or more types.

[0051] The tensile strength, Young's modulus, elongation at break, and stress at break can be measured specifically by the following measurement methods. <Methods for measuring tensile strength, Young's modulus, elongation at break, and stress at break> A cylindrical sample of the adhesive layer cut out from the area to be measured was rolled to a diameter of 30 mm x 1 mm, and chucked at the top and bottom 5 mm with a chuck distance of 10 mm. When pulled at a speed of 50 mm / min, the tensile strength was calculated from the maximum stress, the initial tensile modulus (Young's modulus) from the slope at 50% elongation, and the elongation at break and stress at break, respectively, from the elongation and stress at break, from the stress and elongation at break, which were measured using a tensile testing machine (AUTOGRAPH AGS-X, manufactured by Shimadzu Corporation).

[0052] Examples of the elastic modulus include the elastic modulus at −20° C., the elastic modulus at room temperature (25° C.), and the elastic modulus at 80° C. In addition, examples of the elastic modulus include the storage elastic modulus and the loss elastic modulus.

[0053] The storage modulus of the first region 11 and the second region 12 at −20° C. is not particularly limited, but can be selected, for example, from within the range of 10 kPa to 100 MPa.

[0054] The storage modulus of the first region 11 and the second region 12 at 25° C. is not particularly limited, but can be selected, for example, from within the range of 1 kPa to 100 MPa.

[0055] The storage modulus of the first region 11 and the second region 12 at 80° C. is not particularly limited, but can be selected, for example, from within the range of 10 kPa to 10 MPa.

[0056] The storage modulus of the pressure-sensitive adhesive layer is a value measured by dynamic viscoelasticity. The storage modulus can be controlled by the type of base polymer of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, the monomer composition, weight-average molecular weight, the amount of crosslinking agent used (added amount), and the type and content of other additives. Specifically, the elastic modulus (storage modulus) can be measured by the following measurement method.

[0057] <Method for measuring elastic modulus> Multiple pieces of the adhesive layer cut from the area to be measured are laminated together to produce an adhesive sheet approximately 1 mm thick, which is then punched out to obtain cylindrical pellets (9 mm in diameter) as measurement samples. The measurement samples are then fixed to a parallel plate jig with a diameter of 8 mm using a dynamic viscoelasticity measuring device (product name "ARES-G2", manufactured by TA Instruments) and subjected to dynamic viscoelasticity measurement. In this measurement, the measurement mode is shear mode, the measurement temperature range is -70°C to 150°C, the heating rate is 5°C / min, and the frequency is 1 Hz. The storage moduli at -20°C, 25°C, and 80°C are then read from the measurement results.

[0058] The surface hardness is an AFM hardness. Specifically, the surface hardness can be measured by the following measurement method. <Surface hardness> The adhesive layer in the area to be measured is cut into pieces approximately 1 cm square and fixed to a support (glass slide, manufactured by Matsunami Glass Industry Co., Ltd.) to prepare a sample for AFM measurement. AFM measurement is performed under the following conditions to obtain a load-displacement curve. AFM measurement conditions Equipment: Asylum Research Jupiter XR, manufactured by Oxford Instruments Cantilever used: AC240TS (Si, spring constant equivalent to 1.7N / m) Measurement mode: AFM force curve mapping Measurement temperature: room temperature Scan rate: 2Hz Measurement range: The boundary area between the first and second areas is the center of the measurement, and an 80 μm x 20 μm range is scanned (128 x 16 pixels). Hardness: The average value of the elastic modulus in a 10 μm×20 μm area is calculated and used for each of the first and second regions.

[0059] The gel fractions (proportions of solvent-insoluble components) of the first region 11 and the second region 12 are not particularly limited, but can be selected from within the range of, for example, 40% or more (for example, 40 to 100%).

[0060] The swelling degree of the first region 11 and the second region 12 is not particularly limited, but can be selected, for example, from within the range of 1 to 20 times.

[0061] Specifically, the gel fraction and swelling degree are values ​​calculated by the following "Method for measuring gel fraction and swelling degree", for example.

[0062] <Method for measuring gel fraction and swelling degree> Approximately 0.1 g of the adhesive layer in the area to be measured is collected, wrapped in a porous tetrafluoroethylene sheet (trade name "NTF1122", manufactured by Nitto Denko Corporation) with an average pore size of 0.2 μm, and then tied with kite string. The weight at this time is measured and this weight is defined as the pre-immersion weight X. The pre-immersion weight is the total weight of the adhesive layer (the adhesive layer collected above), the tetrafluoroethylene sheet, and the kite string. The total weight of the tetrafluoroethylene sheet and the kite string is also measured, and this weight is defined as the wrapping weight Y. Next, the adhesive layer wrapped in the tetrafluoroethylene sheet and tied with kite string (referred to as the "sample") is placed in a 50 ml container filled with ethyl acetate and allowed to stand at 23°C for 7 days. Thereafter, the sample (after ethyl acetate treatment) is removed from the container and transferred to an aluminum cup. The weight of the sample at this time is defined as Z0. Then, the sample is dried in a dryer at 130° C. for 2 hours to remove the ethyl acetate, and then the weight of the sample is measured, and this weight is defined as the post-immersion weight Z. Then, the gel fraction is calculated using the following formula. Gel fraction [% (weight%)] = (ZY) / (XY) × 100 Swelling ratio [times] = (Z0-Y) / (ZY)

[0063] The gel fraction and swelling degree can be controlled by, for example, the type and monomer composition of the base polymer of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, the weight average molecular weight, the type and amount (addition amount) of the crosslinking agent, and the like.

[0064] The optical properties include transparency, visible light transmittance, total light transmittance, haze value, refractive index, and the like.

[0065] The transmittance (total light transmittance) of the first region 11 and the second region 12 is not particularly limited, but can be selected, for example, from the range of 1 to 100%. The total light transmittance is a value measured in accordance with JIS K7361-1.

[0066] The haze values ​​of the first region 11 and the second region 12 are not particularly limited, but can be selected, for example, from a range of 99% or less (e.g., 0 to 99%). The "haze value" refers to the ratio of diffuse transmitted light to total transmitted light when visible light is irradiated onto a measurement target, and is also called the cloudiness value. The haze value can be expressed by the following formula: Th(%)=Td / Tt×100 In the above formula, Th is the haze value (%), Td is the scattered light transmittance, and Tt is the total light transmittance. The haze value can be adjusted, for example, by selecting the composition, thickness, etc. of the pressure-sensitive adhesive layer.

[0067] The refractive index of the first region 11 and the second region 12 is not particularly limited, but can be selected, for example, from within the range of 1.1 to 1.9.

[0068] In addition, when measuring the various physical properties described in this specification, if it is difficult to cut out a pressure-sensitive adhesive layer of a predetermined size from the area to be measured, a pressure-sensitive adhesive layer of the same composition as the area to be measured may be prepared, and a measurement sample may be prepared by cutting out a pressure-sensitive adhesive layer of the predetermined size from the pressure-sensitive adhesive layer.

[0069] (Method of manufacturing pressure-sensitive adhesive layer) The pressure-sensitive adhesive layer having the first region and the second region can be produced by a known or conventional method. Examples of the method for producing the pressure-sensitive adhesive layer include methods 1 to 4. The first to fourth methods may be used alone or in combination of two or more.

[0070] The first method is to use a pressure-sensitive adhesive composition forming the first region and a pressure-sensitive adhesive composition forming the second region that have different compositions. Examples of different pressure-sensitive adhesive compositions include compositions that differ in the type of base polymer of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, the monomer composition of the base polymer, the weight-average molecular weight of the base polymer, the type of crosslinking agent, the amount of crosslinking agent used (added amount), and the types and contents of other additives. For example, when the amount of crosslinking agent used is different, a region using a larger amount of crosslinking agent becomes a relatively hard region, and a region using a smaller amount of crosslinking agent becomes a relatively soft region.

[0071] Examples of the base polymer constituting the first region and the second region include known or commonly used polymers, such as acrylic polymers, urethane acrylate resins, urethane resins, rubber resins, epoxy resins, epoxy acrylate resins, oxetane resins, silicone resins, silicone acrylic resins, polyester resins, polyether resins (such as polyvinyl ether), polyamide resins, fluorine-based resins, vinyl acetate / vinyl chloride copolymers, and polyolefins.

[0072] Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, amine-based crosslinking agents, silicone-based crosslinking agents, silane-based crosslinking agents, and polyfunctional monomers such as polyfunctional (meth)acrylates. In this specification, the term "crosslinking agent" refers to a compound capable of forming crosslinks in a resin, and may also be referred to as a "curing agent."

[0073] Examples of the other additives include crosslinking accelerators, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenols, etc.), oligomers, antioxidants, fillers (metal powders, organic fillers, inorganic fillers, etc.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, granular materials, foil-like materials, and release adjusters.

[0074] In the first method, for example, first, a pressure-sensitive adhesive composition forming the first region and a pressure-sensitive adhesive composition forming the second region are applied to the release-treated surface of the same release liner or substrate, respectively. The application of the pressure-sensitive adhesive composition forming the first region and the pressure-sensitive adhesive composition forming the second region may be performed simultaneously or sequentially. After applying the pressure-sensitive adhesive composition to the release-treated surface of the release liner or the substrate to form a pressure-sensitive adhesive composition layer, the pressure-sensitive adhesive composition layer is solidified by volatilizing and removing the solvent by heating or by polymerization by irradiation with active energy rays, thereby forming a pressure-sensitive adhesive layer and producing a pressure-sensitive adhesive layer having a first region and a second region. Furthermore, if necessary, heating, drying, etc. may be performed in addition to the irradiation with active energy rays.

[0075] In the second method, the same adhesive composition is used as the adhesive composition for forming the first region and the adhesive composition for forming the second region, a modifier is added so that the blending amounts in the region to be the first region and the region to be the second region are different, and then an adhesive layer is formed. In this case, an active energy ray-polymerizable adhesive composition can be used as the adhesive composition.

[0076] In the second method, for example, first, a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer is applied to the release-treated surface of a release liner or to a substrate. After the pressure-sensitive adhesive composition is applied to the release-treated surface of a release liner or to a substrate to form a pressure-sensitive adhesive composition layer, a modifier is added to the region to be the first region and / or the region to be the second region. The addition can be carried out by application. The modifier may be added to only one of the region to be the first region and the region to be the second region, or to both. When added to both, the amounts added are made to differ. The modifier added may be the modifier itself, or may be a solution or dispersion in which it is dissolved or dispersed in a solvent.

[0077] The modifier can be any modifier commonly used in the field of pressure-sensitive adhesives. Examples include polymerization initiators, crosslinking agents, UV absorbers, rust inhibitors, antistatic agents, crosslinking accelerators, silane coupling agents, tackifying resins, antioxidants, colorants such as dyes, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, and fillers. Regions containing a high amount of crosslinking agent have a high crosslink density of the base polymer when a pressure-sensitive adhesive layer is formed, resulting in relatively hard regions. Regions containing a high amount of plasticizer are relatively soft regions. After the addition of the modifier, the pressure-sensitive adhesive composition layer is solidified by volatilizing and removing the solvent through heating or by polymerization through active energy ray irradiation, thereby forming a pressure-sensitive adhesive layer having a first region and a second region.

[0078] In a third method, the same pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive composition for forming the first region and the pressure-sensitive adhesive composition for forming the second region, but the degrees of polymerization are different. In this case, an active energy ray-polymerizable pressure-sensitive adhesive composition can be used as the pressure-sensitive adhesive composition.

[0079] In the third method, for example, a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer is first applied to the release-treated surface of a release liner or a substrate. After the pressure-sensitive adhesive composition is applied to the release-treated surface of a release liner or a substrate to form a pressure-sensitive adhesive composition layer, a photomask is placed over a portion of the layer, and the pressure-sensitive adhesive composition layer is irradiated with active energy rays. If necessary, heating, drying, or the like may be performed in addition to the irradiation of active energy rays. In this way, the pressure-sensitive adhesive layer is formed by solidifying the pressure-sensitive adhesive composition layer through polymerization via active energy ray irradiation. The area covered with the photomask is not irradiated with active energy rays or the amount of active energy ray irradiation is small, resulting in a relatively low degree of polymerization in that area. On the other hand, the area not covered with the photomask is irradiated with a large amount of active energy ray irradiation, resulting in a relatively high degree of polymerization in that area. The two areas formed in this way have different physical properties, such as hardness, and can be referred to as a first area and a second area.

[0080] In a third method, the pressure-sensitive adhesive composition layer may be entirely covered with a photomask having regions with different transmittances of active energy rays, and then irradiated with active energy rays. In this way, a pressure-sensitive adhesive layer having first and second regions with different exposure doses of active energy rays can be produced.

[0081] In a fourth method, a pressure-sensitive adhesive layer is formed using the same pressure-sensitive adhesive composition as the pressure-sensitive adhesive composition forming the first region and the pressure-sensitive adhesive composition forming the second region, and then the pressure-sensitive adhesive layer is impregnated with the modifier so that the blending amounts in the region to be the first region and the region to be the second region are different. In this case, an active energy ray-polymerizable pressure-sensitive adhesive composition can be used as the pressure-sensitive adhesive composition.

[0082] In the fourth method, for example, a pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer is first applied to the release-treated surface of a release liner or to a substrate. After applying the pressure-sensitive adhesive composition to the release-treated surface of a release liner or to a substrate to form a pressure-sensitive adhesive composition layer, the pressure-sensitive adhesive composition layer is solidified by volatilizing and removing the solvent through heating or by polymerization through irradiation with active energy rays, thereby forming a pressure-sensitive adhesive layer. Subsequently, a modifier is impregnated into the region to be the first region and / or the region to be the second region. In this manner, a pressure-sensitive adhesive layer having a first region and a second region can be produced.

[0083] Impregnation can be carried out by coating. The modifier may be impregnated into only one of the regions to be the first region and the region to be the second region, or both. When both are impregnated, the amounts added are made different. The modifier to be impregnated may be the modifier itself, or may be a solution or dispersion in which the modifier is dissolved or dispersed in a solvent.

[0084] (base material) When the pressure-sensitive adhesive sheet of the present invention is a substrate-attached pressure-sensitive adhesive sheet or the like, the substrate is not particularly limited, and examples thereof include various optical films such as plastic films, anti-reflection (AR) films, anti-glare (AG) films, polarizing plates, and retardation plates. Examples of the substrate include porous materials such as paper, cloth, and nonwoven fabrics, nets, foam sheets, and metal foils. Examples of materials for the plastic film or the like include polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymers, and cyclic olefin polymers such as "Arton" (a cyclic olefin polymer, manufactured by JSR Corporation) and "Zeonor" (a cyclic olefin polymer, manufactured by Zeon Corporation). These plastic materials may be used alone or in combination.

[0085] The thickness of the substrate is not particularly limited, but is preferably 10 to 150 μm, more preferably 15 to 125 μm, and even more preferably 25 to 100 μm. The substrate may have either a single layer or multiple layers. The surface of the substrate may be appropriately subjected to a known or commonly used surface treatment, such as a physical treatment such as a corona discharge treatment or a plasma treatment, or a chemical treatment such as a primer treatment.

[0086] The pressure-sensitive adhesive sheet may have a release liner provided on the surface (adhesive surface or adhesive surface) of the pressure-sensitive adhesive layer or the like until use. When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, each adhesive surface may be protected by two release liners, or may be protected by a single release liner with release surfaces on both sides in a rolled form (rolled body). The release liner is used as a protective material for the pressure-sensitive adhesive layer and is peeled off when the pressure-sensitive adhesive sheet is attached to the adherend. When the pressure-sensitive adhesive sheet is a substrate-less pressure-sensitive adhesive sheet or the like, the release liner also serves as a support for the pressure-sensitive adhesive layer. The release liner does not necessarily have to be provided.

[0087] Examples of the configuration of the pressure-sensitive adhesive sheet include the configuration of pressure-sensitive adhesive sheet 1 shown in Figure 1: [pressure-sensitive adhesive layer / release liner], [release liner / pressure-sensitive adhesive layer / release liner], [substrate / pressure-sensitive adhesive layer / release liner], [release liner / pressure-sensitive adhesive layer / substrate / pressure-sensitive adhesive layer / release liner], or [substrate / pressure-sensitive adhesive layer / substrate / pressure-sensitive adhesive layer / release liner]. Among the above configurations, in configurations having two pressure-sensitive adhesive layers, at least one pressure-sensitive adhesive layer is the pressure-sensitive adhesive layer of the present invention, and from the viewpoint of the foldability of the pressure-sensitive adhesive sheet, it is preferable that both are the pressure-sensitive adhesive layer of the present invention. Furthermore, the arrangement shapes of the first region, second region, and other region in the two pressure-sensitive adhesive layers of the present invention may be the same or different.

[0088] The use of the pressure-sensitive adhesive sheet of the present invention is not particularly limited, and it can be used for any purpose. The pressure-sensitive adhesive sheet of the present invention can be used, for example, for optical purposes, i.e., for bonding to optical components. The pressure-sensitive adhesive sheet of the present invention is used, for example, in optical components such as electrical and electronic devices, when attaching (mounting) various members or components to predetermined locations (e.g., housings, etc.). Note that "electrical and electronic devices" refers to devices that fall into at least either electrical or electronic categories. Examples of the electrical and electronic devices include image display devices such as liquid crystal displays, electroluminescence displays, and plasma displays, as well as portable electronic devices. Examples of the image display devices include image display devices in the portable electronic devices, and displays (roll displays) inside and outside vehicles such as trains and buses.

[0089] Examples of the portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (for example, wristwear devices worn on the wrist like a wristwatch, modular devices worn on a part of the body with a clip or strap, eyewear devices including eyeglasses (monocular and binocular, including head-mounted devices), clothing devices attached to shirts, socks, hats, etc. as accessories, and earwear devices attached to the ears like earphones), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game devices, electronic dictionaries, electronic organizers, e-books, in-car information devices, portable radios, portable televisions, portable printers, portable scanners, and portable modems. Note that in this specification, "portable" does not simply mean being portable, but rather means having a level of portability that allows an individual (average adult) to carry it relatively easily.

[0090] When the pressure-sensitive adhesive sheet of the present invention is attached to an adherend and folded, fold marks are unlikely to form at the folded portion. Therefore, the pressure-sensitive adhesive sheet of the present invention is preferably used for bonding components (particularly between components) in electric and electronic devices that are used by folding, for example, electric and electronic devices having a foldable adherend, such as a foldable image display device (flexible display) (particularly, a foldable image display device (foldable display)).

[0091] The pressure-sensitive adhesive sheet is preferably used, for example, to bond components or modules constituting a mobile electronic device together, or to fasten components or modules constituting a mobile electronic device to a housing. More specifically, examples of such applications include bonding a cover glass or lens (particularly a glass lens) to a touch panel or touch sensor film (particularly a touch sensor film having metal wiring such as a metal mesh film or a silver nanowire film), bonding a polarizing film to a touch panel or touch sensor, bonding a display panel to a touch panel or touch sensor film, fixing a cover glass or lens (particularly a glass lens) to a housing, fixing a display panel to a housing, fixing an input device such as a sheet-like keyboard or touch panel to a housing, bonding a protective panel of an information display unit to a housing, bonding housings together, bonding a housing to a decorative sheet, and fixing or bonding various components and modules constituting a mobile electronic device. In this specification, the term "display panel" refers to a structure composed of at least a lens (particularly a glass lens) and a touch panel. In this specification, the term "lens" is intended to encompass both transparent bodies that refract light and transparent bodies that do not refract light. In other words, the lens in this specification also includes a simple window panel that has no refractive effect.

[0092] The pressure-sensitive adhesive sheet can also be suitably used for transparent conductive films (metal mesh films, silver nanowire films) in which the metal wiring is metal mesh wiring or silver nanowires, particularly optical components (touch sensor films) having metal mesh films. When an optical component having metal wiring such as a metal mesh film or silver nanowire film is bonded via the pressure-sensitive adhesive sheet, the low dielectric constant suppresses noise generation, while the adhesive sheet has sufficient adhesive strength and excellent drop impact resistance.

[0093] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. [Example]

[0094] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0095] Example 1 (Preparation of acrylic prepolymer solution) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, 71 parts by mass of n-octyl acrylate (NOAA), 19 parts by mass of n-butyl acrylate (BA), 2 parts by mass of N-vinyl-2-pyrrolidone (NVP), 8 parts by mass of 4-hydroxybutyl acrylate (4HBA), 0.05 parts by mass of a photopolymerization initiator (trade name "Omnirad 819", manufactured by IGM Resins Italia Srl), and 0.05 parts by mass of a photopolymerization initiator (trade name "Omnirad 184", manufactured by IGM Resins Italia Srl) were added, and then nitrogen gas was introduced and the mixture was purged with nitrogen for about 20 minutes while stirring. Thereafter, nitrogen gas was introduced at 5 mW / cm. 2 The reaction rate was adjusted to 5 to 15%, and an acrylic prepolymer solution was obtained.

[0096] <Preparation of acrylic oligomer solution> First, in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, a mixture containing 60 parts by weight of dicyclopentanyl methacrylate (DCPMA), 40 parts by weight of methyl methacrylate (MMA), 3.5 parts by weight of α-thioglycerol as a chain transfer agent, and 100 parts by weight of toluene as a polymerization solvent was stirred at 70°C for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was added to the mixture to prepare a reaction solution, which was then reacted under a nitrogen atmosphere at 70°C for 2 hours and then at 80°C for 2 hours (polymerization reaction). Next, the reaction solution was heated to 130°C to volatilize and remove the toluene, chain transfer agent, and unreacted monomer. This yielded an acrylic oligomer (solid). The weight-average molecular weight of this acrylic oligomer was 5100. This acrylic oligomer was dissolved in BA to a concentration of 50% by mass to obtain an acrylic oligomer solution.

[0097] (Preparation of Pressure-Sensitive Adhesive Composition 1) To the acrylic prepolymer solution, 1 part by mass of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent, 1.5 parts by mass of the acrylic oligomer solution, 0.5 parts by mass of γ-glycidyloxypropyltrimethoxysilane as a silane coupling agent, and 0.02 parts by mass of a photopolymerization initiator (product name "Omnirad 819", manufactured by IGM Resins Italia Srl) were added and stirred to prepare adhesive composition 1.

[0098] (Preparation of Pressure-Sensitive Adhesive Composition 2) To the acrylic prepolymer solution, 0.1 parts by mass of 1,9-nonanediol diacrylate (NDDA) as a crosslinking agent, 1.5 parts by mass of the acrylic oligomer solution, 0.5 parts by mass of γ-glycidyloxypropyltrimethoxysilane as a silane coupling agent, and 0.02 parts by mass of a photopolymerization initiator (product name "Omnirad 819", manufactured by IGM Resins Italia Srl) were added and stirred to prepare adhesive composition 2.

[0099] (Preparation of adhesive sheet) As shown in FIG. 7 , the pressure-sensitive adhesive composition 1 (21) and the pressure-sensitive adhesive composition 2 (22) were placed near edge E5 on the release-treated surface of a release liner 2 (trade name "MRE38", manufactured by Mitsubishi Chemical Corporation; polyethylene terephthalate film with one side subjected to a release treatment, thickness 38 μm) in the order of pressure-sensitive adhesive composition 1 (21), pressure-sensitive adhesive composition 2 (22), pressure-sensitive adhesive composition 1 (21), pressure-sensitive adhesive composition 2 (22), pressure-sensitive adhesive composition 1 (21). Thereafter, the applicator 3 was moved from edge E5 toward the other edge, thereby spreading pressure-sensitive adhesive composition 1 and pressure-sensitive adhesive composition 2 in one direction to form a pressure-sensitive adhesive composition layer (thickness 50 μm). The release-treated surface of a release liner (trade name "MRF38", manufactured by Mitsubishi Chemical Corporation) was then attached to the pressure-sensitive adhesive composition layer. Next, the adhesive composition was measured using a black light at 2.5 mW / cm 2 The cumulative amount of ultraviolet light is 2400mJ / cm 2 Polymerization was carried out by irradiating until the crosslinking agent reached a value of 1. In this way, a pressure-sensitive adhesive sheet 1 was produced, which included a relatively hard first region 11 containing 1 part by mass of crosslinking agent and a relatively soft second region containing 0.1 parts by mass of crosslinking agent. The widths of the first region and the second region in the resulting pressure-sensitive adhesive sheet 1 were each 20 mm.

[0100] <Measurement of adhesive layer hardness using nanoindentation method> The adhesive layer obtained in Example 1 was cut into pieces approximately 1 cm square and fixed to a support (a slide glass, manufactured by Matsunami Glass Industry Co., Ltd.) to prepare a sample for nanoindentation measurement. Nanoindentation measurement was performed under the following conditions to obtain a load-displacement curve. Nanoindentation measurement conditions Equipment: Triboindenter manufactured by Hysitron Inc. Indenter used: Conical (spherical: radius 10μm) Measurement method: Single indentation measurement Measurement temperature: room temperature Indentation depth: 5000nm

[0101] The hardness H is the load (maximum load P max ) and the contact area between the indenter and the sample (contact projected area Ac) at that time, was calculated using the following formula (1). H=P max / Ac (1)

[0102] Figure 8 shows a graph of the nanoindentation hardness in the vicinity of the first region and the second region. As shown in Figure 8, with respect to the hardness measured by the nanoindentation method, it was possible to produce a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer having a first region, which is a relatively hard portion, and a second region, which is a relatively soft portion, in the same plane. Such a pressure-sensitive adhesive sheet can be folded for use, and when attached to an adherend and folded, creases are unlikely to occur at the folded portion.

[0103] Variations of the invention according to the present disclosure are described below. [Supplementary Note 1] A pressure-sensitive adhesive layer having, in the same plane, a first region that is a single linear region and a second region that is parallel to the first region and is also a single linear region, The pressure-sensitive adhesive sheet has different physical properties from the first region and the second region. [Appendix 2] The pressure-sensitive adhesive sheet according to Appendix 1, wherein the physical property is hardness. [Appendix 3] The pressure-sensitive adhesive sheet described in Appendix 1 or 2, wherein the hardness is one or more selected from the group consisting of tensile strength, modulus of elasticity, Young's modulus, elongation at break, stress at break, surface hardness, swelling degree, gel fraction, hardness measured by nanoindentation method, and residual stress. [Appendix 4] The pressure-sensitive adhesive sheet according to any one of Appendices 1 to 3, wherein the first region and the second region each have a linear shape. [Appendix 5] The pressure-sensitive adhesive sheet according to any one of Appendices 1 to 4, wherein the first regions and the second regions are alternately arranged in one direction of the pressure-sensitive adhesive layer. [Appendix 6] The pressure-sensitive adhesive sheet according to any one of Appendices 1 to 5, wherein the first region and the second region extend from one end side to the other end side in a direction perpendicular to the thickness direction of the pressure-sensitive adhesive layer. [Appendix 7] An adhesive sheet according to Appendix 2, which is used by being attached to a foldable adherend, the first region being included in an area corresponding to the fold of the adherend, the second region being adjacent to both sides of the first region, and the hardness of the first region being harder than the hardness of the second region. [Appendix 8] The hardness of the first region is harder than the hardness of the second region; The adhesive sheet described in Appendix 2, wherein in the adhesive layer, the first region and the second region are positioned alternately adjacent to each other in one direction of the adhesive layer, and the first region is located within a range of ±1 mm from the center in the one direction. [Appendix 9] The pressure-sensitive adhesive sheet according to any one of Appendices 1 to 8, which is used by being attached to an optical member. [Appendix 10] The pressure-sensitive adhesive sheet according to Appendix 9, which is used by being attached to a bendable adherend. [Explanation of symbols]

[0104] 1 adhesive layer 2 Release liner 3 Applicator 10 adhesive sheet 11 First area 12 Second area 21 Pressure-sensitive adhesive composition 1 22 Pressure-sensitive adhesive composition 2 B Bending part D1 First direction D2 Second direction E1 First edge E2 Second edge E3 third edge E4 Fourth edge E5 Fifth edge

Claims

1. a pressure-sensitive adhesive layer having, in the same plane, a first region which is a single linear region and a second region which is parallel to the first region and is also a single linear region; The pressure-sensitive adhesive sheet has different physical properties from the first region and the second region.

2. The pressure-sensitive adhesive sheet according to claim 1 , wherein the physical property is hardness.

3. 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the hardness is one or more selected from the group consisting of tensile strength, modulus of elasticity, Young's modulus, elongation at break, stress at break, surface hardness, swelling degree, gel fraction, hardness measured by nanoindentation, and residual stress.

4. The pressure-sensitive adhesive sheet according to claim 1 , wherein the first region and the second region each have a linear shape.

5. The pressure-sensitive adhesive sheet according to claim 1 , wherein the first regions and the second regions are alternately arranged in one direction of the pressure-sensitive adhesive layer.

6. The pressure-sensitive adhesive sheet according to claim 1 , wherein the first region and the second region extend from one end side to the other end side in a direction perpendicular to the thickness direction of the pressure-sensitive adhesive layer.

7. 3. The pressure-sensitive adhesive sheet according to claim 2, which is used by being attached to a foldable adherend, the first region being included in an area corresponding to a fold of the adherend, the second region being adjacent to both sides of the first region, and the hardness of the first region being harder than the hardness of the second region.

8. The hardness of the first region is greater than the hardness of the second region; The pressure-sensitive adhesive sheet according to claim 2, wherein the first regions and the second regions are alternately adjacent to each other in one direction of the pressure-sensitive adhesive layer, and the first region is located within a range of ±1 mm from the center in the one direction.

9. The pressure-sensitive adhesive sheet according to claim 1 or 2, which is used by being attached to an optical member.

10. The pressure-sensitive adhesive sheet according to claim 9 , which is used by being attached to a foldable adherend.

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