Optical adhesive sheet

Abstract

To provide an optical adhesive sheet which suppresses surrounding contamination, improves handling performance and excels in adhesive reliability.SOLUTION: There is provided an optical adhesive sheet 1 which comprises a release liner 2 and an adhesive layer 3 in order toward one side in the thickness direction. The maximum length L of the adhesive layer 3 in the orthogonal direction orthogonal to the thickness direction is 200 mm or more. The release liner 2 is larger than the adhesive layer 3 and encloses the adhesive layer 3 when viewed in the thickness direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical adhesive sheet, and more particularly to an optical adhesive sheet suitably used for attaching components for image display devices. [Background technology]

[0002] An optical adhesive sheet is known that comprises a release liner, an adhesive layer, and a second release liner in this order (see, for example, Patent Document 1 below).

[0003] In the optical adhesive sheet described in Patent Document 1, a release liner is peeled off from the adhesive layer, and then the adhesive layer is attached to a component of an image display device. The image display device includes a tablet. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-122140 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, when attaching the aforementioned adhesive layer to the tablet components, the size of the adhesive layer also increases due to the large size of the tablet. Consequently, the size of the optical adhesive sheet containing the adhesive layer also increases. This necessitates transporting the optical adhesive sheet by machine.

[0006] In this case, if the adhesive layer is the same size as the release liner and the second release liner, the edges of the adhesive layer tend to protrude outward from the release liner and the second release liner. This results in the problem of the adhesive composition of the adhesive layer contaminating the machine.

[0007] In addition, when the above-mentioned protrusion occurs, the end of the optical adhesive sheet adheres to the machine unintentionally, resulting in a problem that the handling property of the optical adhesive sheet deteriorates.

[0008] Furthermore, when the above-mentioned protrusion occurs, the adhesive layer has a defect at the end, resulting in a lack of adhesive. Then, the adhesive reliability of the adhesive layer deteriorates.

[0009] The present invention provides an optical adhesive sheet that suppresses surrounding contamination, improves handling property, and has excellent adhesive reliability.

Means for Solving the Problems

[0010] The present invention (1) includes a release liner and an adhesive layer provided in this order toward one side in the thickness direction, and the maximum length L of the adhesive layer in the orthogonal direction orthogonal to the thickness direction is 200 mm or more, and the release liner is larger than the adhesive layer and includes the adhesive layer when viewed in the thickness direction, and includes an optical adhesive sheet.

[0011] In this optical adhesive sheet, since the maximum length L of the adhesive layer is 200 mm or more, the adhesive layer can be attached to a member in a large image display device such as a tablet.

[0012] Also, even when the above-mentioned length L is 200 mm or more, in the optical adhesive sheet of the present invention, the release liner is larger than the adhesive layer and includes the adhesive layer when viewed in the thickness direction, so the release liner suppresses the end of the adhesive layer from protruding. Therefore, the above-mentioned contamination to the surroundings by the adhesive layer can be suppressed.

[0013] Furthermore, in this optical adhesive sheet, since the protrusion of the end of the adhesive layer is suppressed, it has excellent handling property.

[0014] Furthermore, in this optical adhesive sheet, since the protrusion of the end of the adhesive layer is suppressed, the lack of adhesive is suppressed and the adhesive layer has excellent adhesive reliability.

[0015] The present invention (2) includes the optical adhesive sheet described in (1), wherein the amount of deflection D measured in the deflection test described below is 7 mm or less.

[0016] Deflection Test: Prepare a sample by shaping the optical adhesive sheet to a length of 100 mm and a width of 25 mm. Prepare a stand with a top surface and a height of 50 mm or more. Fix the surface of a 50 mm long first portion of the sample, including one longitudinal edge, to the top surface, and allow a 50 mm long second portion of the sample, including the other longitudinal edge, to protrude laterally from one end of the top surface. Then, leave it at 23°C for 5 minutes. After that, obtain the amount of movement of the protruding edge of the sample downward from the top surface. Separately, fix the back surface of the first portion to the top surface and obtain the amount of movement. Determine the deflection amount D by taking the average of the two amounts of movement.

[0017] Because this optical adhesive sheet has a deflection amount D of 7 mm or less, it offers even greater ease of handling.

[0018] The present invention (3) is defined as follows: the area P, which is the product of the offset amount of the peeling liner and the thickness of the peeling liner, is 90 × 10 -8 m 2 The above includes the optical adhesive sheet described in (1) or (2).

[0019] The offset amount: The length (mm) of the offset portion that is offset from the adhesive layer in the release liner when viewed in the thickness direction. The aforementioned thickness: The average thickness (μm) at the three points in the offset portion.

[0020] In this optical adhesive sheet, the area P described above is 90 × 10 -8 m 2 Therefore, the adhesive layer can be prevented from lifting away from the release liner.

[0021] The present invention (4) further comprises an adjacent layer adjacent to the opposite side of the release liner from the adhesive layer in the thickness direction, wherein the release liner, the adhesive layer, and the adjacent layer include the optical adhesive sheet described in (2) that satisfies the following formula [1].

[0022] E1 × E2 × (T1 + T2) / [T0 1 / 2 [×100,000] ≥ 2,500 [1]

[0023] E1: Tensile modulus of the peel liner at 23℃ (MPa) E2: Tensile modulus of the adjacent layer at 23℃ (MPa) T1: Thickness of the aforementioned release liner (μm) T2: Thickness of the adjacent layer (μm) T0: Thickness of the adhesive layer (μm)

[0024] When the above-mentioned formula [1] is satisfied, at least one of the following is large: the thickness T1 of the release liner, the tensile modulus E1 of the release liner, the thickness T2 of the adjacent layer, and the tensile modulus E2 of the adjacent layer. Therefore, even if the adhesive layer is thick, the release liner and / or adjacent layer tend to become harder, which reduces the amount of deflection D of the optical adhesive sheet.

[0025] Alternatively, if the above-mentioned formula [1] is satisfied, the adhesive layer is thin. Therefore, even if at least one of the group consisting of the thickness T1 of the release liner, the tensile modulus E1 of the release liner, the thickness T2 of the adjacent layer, and the tensile modulus E2 of the adjacent layer is small, the optical adhesive sheet can maintain toughness, and thus the above-mentioned amount of deflection D of the optical adhesive sheet can be reduced.

[0026] The present invention (5) includes the optical adhesive sheet described in (4), wherein the adjacent layer is a second release liner.

[0027] The present invention (6) includes the optical adhesive sheet according to (5), in which the second release liner is larger than the adhesive layer and includes the adhesive layer when viewed in the thickness direction.

[0028] In this optical adhesive sheet, since the second release liner is larger than the adhesive layer and includes the adhesive layer when viewed in the thickness direction, the second release liner further suppresses the protrusion of the end portion of the adhesive layer, and the handling property is further improved.

[0029] In the present invention (7), the area P2, which is the product of the second offset amount of the second release liner defined below and the thickness of the second release liner, is 90×10 -8 m 2 or more, and includes the optical adhesive sheet according to (6).

[0030] The offset amount: the length (mm) of the second offset portion that is displaced from the adhesive layer in the second release liner when viewed in the thickness direction The thickness: the average thickness (μm) at three points in the second offset portion

[0031] In this optical adhesive sheet, since the above-mentioned area P2 is 90×10 -8 m 2 or more, it is possible to suppress the adhesive layer from floating from the second release liner.

[0032] The present invention (8) includes the optical adhesive sheet according to (4), in which the adjacent layer is a member for an image display device.

[0033] The present invention (9) includes the optical adhesive sheet according to (8), in which the peripheral edge of the member for an image display device coincides with the peripheral edge of the adhesive layer when viewed in the thickness direction.

[0034] The present invention (10) includes an optical adhesive sheet according to any one of claims (1) to (9), wherein one surface of the release liner in the thickness direction has a recess that is recessed toward the other side in the thickness direction around the peripheral edge of the adhesive layer, and the depth of the recess is 30 μm or less.

[0035] The present invention (11) includes an optical adhesive sheet according to any one of claims (1) to (10), wherein the indentation hardness H of the adhesive layer at 23°C is 10 kPa or less.

[0036] In this optical adhesive sheet, the indentation hardness H of the adhesive layer at 23°C is 10 kPa or less, so the adhesive layer is suitable for attaching components to a foldable image display device.

[0037] The present invention (12) includes an optical adhesive sheet according to any one of claims (1) to (11), wherein the shear storage modulus G' of the adhesive layer at 25°C is 100 kPa or less.

[0038] In this optical adhesive sheet, the shear storage modulus G' of the adhesive layer at 25°C is 100 kPa or less, so the adhesive layer is suitable for attaching components to a foldable image display device.

[0039] The present invention (13) includes an optical adhesive sheet comprising the adhesive layer provided in an image display device, wherein the image display device comprises the adhesive layer and a pair of image display device members formed on one surface and the other surface of the optical adhesive sheet in the thickness direction, according to any one of the claims (1) to (12). [Effects of the Invention]

[0040] The optical adhesive sheet of the present invention suppresses contamination of the surroundings, improves handling, and has excellent adhesive reliability. [Brief explanation of the drawing]

[0041] [Figure 1] This is a cross-sectional view of an optical adhesive sheet according to one embodiment of the present disclosure. [Figure 2] This is a cross-sectional view illustrating the measurement of the amount of deflection of an optical adhesive sheet. [Figure 3] Figures 3A to 3D are process diagrams illustrating the manufacturing method of an optical adhesive sheet. Figure 3A shows the process of preparing the laminate. Figure 3B shows the process of shaping the adhesive layer and the third release liner. Figure 3C shows the process of removing unnecessary parts. Figure 3D shows the process of replacing the third release liner with an adjacent layer and shaping the release liner. [Figure 4] This is a cross-sectional view of an optical adhesive sheet equipped with an image display device component as an adjacent layer. [Figure 5] This is a cross-sectional view of an image display device. [Figure 6] This is a cross-sectional view of a modified optical adhesive sheet. [Figure 7] This is another embodiment of an optical adhesive sheet. [Modes for carrying out the invention]

[0042] 1. Optical adhesive sheet 1 One embodiment of the optical adhesive sheet of the present invention will be described with reference to Figure 1.

[0043] As shown in Figure 1, the optical adhesive sheet 1 has thickness. The optical adhesive sheet 1 is oriented in a planar direction. The planar direction is an example of an orthogonal direction, and is perpendicular to the thickness direction. The shape of the optical adhesive sheet 1 when viewed from one side in the thickness direction is not particularly limited. Examples of the shape of the optical adhesive sheet 1 include rectangular, elliptical, and circular shapes.

[0044] The optical adhesive sheet 1 comprises a release liner 2 and an adhesive layer 3 in order toward one side in the thickness direction. In this embodiment, the optical adhesive sheet 1 comprises a release liner 2, an adhesive layer 3 and an adjacent layer 4 in order toward one side in the thickness direction.

[0045] 1.2 Adhesive layer 3 and its size The adhesive layer 3 is oriented in the direction of the surface. The adhesive layer 3 has a sheet shape. Examples of shapes of the adhesive layer 3 when viewed from one side in the thickness direction include rectangular, elliptical, and circular shapes.

[0046] The maximum length L of the adhesive layer 3 in the planar direction is 200 mm or more.

[0047] The maximum length L of the adhesive layer 3 in the planar direction is the length of the line segment connecting two opposite corners if the shape of the adhesive layer 3 is rectangular. If the shape of the adhesive layer 3 is elliptical, the maximum length L of the adhesive layer 3 in the planar direction is the length along the major axis. If the shape of the adhesive layer 3 is circular, the maximum length L of the adhesive layer 3 in the planar direction is the diameter.

[0048] If the maximum length L of the adhesive layer 3 in the planar direction is less than 200 mm, the adhesive layer 3 cannot be used to attach components to large image display devices such as tablets.

[0049] On the other hand, in the present invention, since the maximum length L of the adhesive layer 3 in the planar direction is 200 mm or more, the adhesive layer 3 can be used to attach components of the large image display device described above.

[0050] The maximum length L of the adhesive layer 3 in the planar direction is preferably 200 mm or more, more preferably 250 mm or more, and even more preferably 300 mm or more. The maximum length L of the adhesive layer 3 in the planar direction is, for example, 3000 mm or less, and also, for example, 2000 mm or less.

[0051] The thickness T0 of the adhesive layer 3 is preferably 5 μm or more, more preferably 10 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more, 50 μm or more, or 100 μm or more. Alternatively, the thickness T0 of the adhesive layer 3 is preferably 500 μm or less, more preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 100 μm or less, 50 μm or less, or 30 μm or less.

[0052] 1.3 Peel-off liner 2 and its size The release liner 2 forms the other side of the optical adhesive sheet 1 in the thickness direction. The release liner 2 is located at the other end of the optical adhesive sheet 1 in the thickness direction. The release liner 2 is larger than the adhesive layer 3 when viewed in the thickness direction. The release liner 2 encloses the adhesive layer 3 when viewed in the thickness direction. For example, the peripheral edges of the release liner 2 are exposed from the adhesive layer 3. The release liner 2 has a shape similar to that of the adhesive layer 3, for example.

[0053] The length L1 of the peel-off liner 2 in the first direction is, for example, 200 mm or more, preferably 201 mm or more, more preferably 203 mm or more, even more preferably 250 mm or more, and even more preferably 300 mm or more. The length L1 of the peel-off liner 2 in the first direction is, for example, 3020 mm or less, and also, for example, 2020 mm or less. The first direction is a direction included in the surface direction and is the direction that defines the maximum length L of the adhesive layer 3 described above.

[0054] The value obtained by subtracting the maximum length L of the adhesive layer 3 in the surface direction from the length L1 of the peel liner 2 in the first direction (L1-L) is, for example, 1 mm or more, preferably 3 mm or more, more preferably 5 mm or more, and even more preferably 10 mm or more. If the above value (L1-L) is above the above lower limit, the effects of the optical adhesive sheet 1, such as suppressing contamination of the surroundings, improving handling, and having excellent adhesive reliability, can be achieved even more reliably.

[0055] The upper limit of the value obtained by subtracting the maximum length L of the adhesive layer 3 in the surface direction from the length L1 of the release liner 2 in the first direction (L1-L) is, for example, 100 mm. If the above value (L1-L) is less than or equal to the above upper limit, it is possible to suppress the deterioration of the handlingability of the optical adhesive sheet 1 caused by an excessive offset portion 21 (described later) of the release liner 2.

[0056] Based on the above-mentioned value (L1-L), the peel-off liner 2 has an offset portion (margin portion) 21. The offset portion 21 is the peripheral edge of the peel-off liner 2 that is along the outer circumference of the adhesive layer 3.

[0057] The thickness T1 of the peel liner 2 is set appropriately so that the area P, described later, is a specific value, and the relationship value with the tensile modulus E1, described later, is a specific value. The thickness T1 of the peel liner 2 is, for example, 10 μm or more, preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 70 μm or more. The thickness T1 of the peel liner 2 is, for example, 200 μm or less, preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less.

[0058] 1.4 Adjacent layer 4 and its size In this embodiment, the adjacent layer 4 forms one side of the optical adhesive sheet 1 in the thickness direction. The adjacent layer 4 is adjacent to the side opposite the release liner 2 to the adhesive layer 3 in the thickness direction. The adjacent layer 4 is located at one end of the optical adhesive sheet 1 in the thickness direction.

[0059] As shown in Figure 1, the peripheral edge of the adjacent layer 4 coincides with the peripheral edge of the release liner 2 when viewed in the thickness direction. Alternatively, as shown in Figure 7, the adjacent layer 4 may be larger than the adhesive layer 3 when viewed in the thickness direction and may encompass the adhesive layer 3. The peripheral edge of the adjacent layer 4 is exposed from the adhesive layer 3. In this case, the adjacent layer 4 has a shape similar to, for example, the adhesive layer 3. The adjacent layer 4 is, for example, a second release liner 4A or an image display device member 11, and in this embodiment, it is preferably a second release liner 4A.

[0060] The length L2 of the adjacent layer 4 in the first direction is, for example, 200 mm or more, preferably 250 mm or more, more preferably 300 mm or more, and even more preferably 500 mm or more. The length L2 of the adjacent layer 4 in the first direction is, for example, 3000 mm or less, and also, for example, 2000 mm or less.

[0061] The value obtained by subtracting the maximum length L of the adhesive layer 3 in the planar direction from the length L2 of the adjacent layer 4 in the first direction (L2-L) is, for example, 0 mm or more, preferably 1 mm or more, preferably 3 mm or more, more preferably 5 mm or more, and even more preferably 10 mm or more.

[0062] As shown in Figure 7, the upper limit of the value obtained by subtracting the maximum length L of the adhesive layer 3 in the planar direction from the length L2 of the adjacent layer 4 in the first direction (L2-L) is, for example, 100 mm. If the above value (L2-L) is less than or equal to the above upper limit, it is possible to suppress the deterioration of the handlingability of the optical adhesive sheet 1 caused by the second offset portion 41 (described later) of the adjacent layer 4 becoming excessive.

[0063] 1.5 Amount of deflection D of optical adhesive sheet 1 The amount of deflection D of the optical adhesive sheet 1 measured in the deflection test described below is, for example, 20 mm or less, preferably 15 mm or less, more preferably 10 mm or less, even more preferably 7 mm or less, and particularly preferably 5 mm or less. The lower limit of the amount of deflection D of the optical adhesive sheet 1 is 0 mm and also 1 mm.

[0064] Deflection Test: A sample 100 is prepared by shaping an optical adhesive sheet 1 to a length of 100 mm and a width of 25 mm. Sample 100 does not have an offset portion 21 (described later) or a second offset portion 41 (described later). As shown in Figure 2, a stand 105 is prepared that has a top surface and a height of 50 mm or more. A first portion 101, 50 mm long and including one longitudinal edge of sample 100, is fixed to the top surface, and a second portion 102, 50 mm long and including the other longitudinal edge of the sample, is made to protrude laterally from one longitudinal edge of the top surface. A weight 106 is placed on the top surface of the first portion 101. This fixes the first portion 101 to the top surface of the weight 106. Then, it is left at 23°C for 5 minutes. After that, the amount of movement D of the protruding edge of sample 100 moving downward from the top surface is obtained. Separately, the back surface of the first portion is fixed to the top surface, and the amount of movement is obtained. The average of the two displacements is calculated as the deflection amount D.

[0065] If the amount of deflection D of the optical adhesive sheet 1 is less than or equal to the upper limit mentioned above, the handling of the optical adhesive sheet 1 will be improved.

[0066] The amount of deflection D is adjusted by adjusting the thickness T1 of the peel liner 2, the tensile modulus E1 (described later) of the peel liner 2, the thickness T2 of the adjacent layer 4, the tensile modulus E2 (described later) of the adjacent layer 4, the shear storage modulus G' (described later) of the adhesive layer 3, and the thickness T0 of the adhesive layer 3. Furthermore, the amount of deflection D can also be adjusted by adjusting the relational values ​​(the left side of equations [1] to [8] described later), the area P (described later), and / or the area P2 (described later).

[0067] 1.6 Physical properties of each layer 1.6.1 Indentation hardness H of adhesive layer 3 The indentation hardness H of the adhesive layer 3 at 23°C is, for example, 20 kPa or less, preferably 10 kPa or less, more preferably 5 kPa or less, even more preferably 4 kPa or less, and particularly preferably 3 kPa or less. The lower limit of the indentation hardness H of the adhesive layer 3 at 23°C is, for example, 0.001 kPa or higher, preferably 0.01 kPa, and more preferably 0.1 kPa. If the indentation hardness H of the adhesive layer 3 at 23°C is below the above upper limit, the adhesive layer 3 is suitably used for attaching components in a foldable image display device. The measurement of the indentation hardness H of the adhesive layer 3 will be described in a later example. The indentation hardness H of the adhesive layer 3 is adjusted by adjusting the formulation (type) of the adhesive composition, which will be described later.

[0068] 1.6.2 Shear storage modulus G' of adhesive layer 3 The shear storage modulus G' of the adhesive layer 3 at 25°C is, for example, 10 kPa or more, preferably 15 kPa or more, more preferably 20 kPa or more, and even more preferably 25 kPa or more. Alternatively, it may be 1000 kPa or less, preferably 700 kPa or less, more preferably 500 kPa or less, even more preferably 300 kPa or less, and even more preferably 200 kPa or less, 100 kPa or less, or 50 kPa or less. If the shear storage modulus G' of the adhesive layer 3 is below the above upper limit, the adhesive layer 3 can achieve the softness required for flexible device applications. The shear storage modulus G' of the adhesive layer 3 is determined by dynamic viscoelasticity measurement at a heating rate of 5°C / min and a frequency of 1 Hz. The shear storage modulus G' of the adhesive layer 3 is adjusted by adjusting the formulation (type) of the adhesive composition, which will be described later.

[0069] 1.6.3 Area P is the product of the offset amount OL and thickness T1 of the peeling liner 2. The area P (=OL × T1), which is the product of the offset amount OL of the peeling liner 2 and the thickness T1 of the peeling liner 2, is, for example, 50 × 10 -8 m 2 Preferably, 90 × 10 -8 m 2 The above is more comfortable, 150 x 10 -8 m 2 More preferably, 200 × 10 -8 m 2 In particular, 300 × 10 -8 m 2 That concludes the explanation. The upper limit of the area P between the offset amount OL of the peeling liner 2 and the thickness T1 of the peeling liner 2 is, for example, 1,000 × 10 -8 m 2 Preferably, 500 × 10 -8 m 2 That is the case.

[0070] The offset amount OL and thickness T1 of the peel liner 2 are defined as follows:

[0071] Offset amount OL of the peel-off liner 2: The length (mm) of the offset portion 21 that is shifted from the adhesive layer 3 in the peel-off liner 2 when viewed in the thickness direction. Thickness T1: Average thickness (μm) at three points in the offset portion 21.

[0072] There are two offset portions 21 in the first direction. Preferably, the offset amount OL of each of the two offset portions 21 is the same.

[0073] The three points are located at the same position in the first direction within the offset portion 21, and are spaced apart from each other in the width direction. The width direction is perpendicular to the thickness direction and the first direction.

[0074] If the area P described above is greater than or equal to the lower limit described above, the offset amount OL is large and / or thick.

[0075] When the offset amount OL of the peel-off liner 2 is large, even if the offset portion 21 deforms, this deformation is less likely to affect the adhesive layer 3. The deformation includes bending of the offset portion 21. Therefore, it is possible to suppress the adhesive layer 3 from unintentionally peeling off (lifting) from the peel-off liner 2.

[0076] Alternatively, if the peel-off liner 2 is thick, deformation of the peel-off liner 2 is suppressed even if the offset portion 21 comes into contact with the conveying machine. Therefore, lifting of the adhesive layer 3 can be suppressed.

[0077] 1.6.4 Tensile modulus E1 of peeling liner 2 The tensile modulus E1 of the peel liner 2 at 23℃ is given by the following relationship (E1 × E2 × (T1 + T2) / [T0 1 / 2The multiplication factor (×100,000) is set appropriately so that it becomes a specific value. The tensile modulus E1 of the peel liner 2 at 23°C is, for example, 1,000 MPa or more, preferably 2,000 MPa or more, more preferably 3,000 MPa or more, and even more preferably 4,000 MPa or more. The upper limit of the tensile modulus E1 of the peel liner 2 at 23°C is, for example, 10,000 MPa.

[0078] The tensile modulus E1 of the peeled liner 2 at 23°C is determined based on the stress-strain curve. Details of the measurement are described in the Examples section.

[0079] 1.6.5 Recess 25 in the peel-off liner 2 One side of the release liner 2 in the thickness direction includes, for example, a recess 25. The recess 25 is recessed toward the other side in the thickness direction around the peripheral edge of the adhesive layer 3. The depth of the recess 25 is, for example, 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less, even more preferably 10 μm or less, and particularly preferably 1 μm or less. The lower limit of the depth of the recess 25 is, for example, 0.001 μm, and also 0 μm. If the depth of the recess 25 is less than or equal to the upper limit described above, it is possible to suppress the release liner 2 from being cut starting from the recess 25.

[0080] 1.6.6 Tensile modulus E2 of adjacent layer 4 The tensile modulus E2 of the adjacent layer 4 at 23°C is set appropriately so that the relationship value described later becomes a specific value. The tensile modulus E2 of the adjacent layer 4 at 23°C is preferably 50 MPa or more, preferably 100 MPa or more, more preferably 150 MPa or more, even more preferably 250 MPa or more, particularly preferably 600 MPa or more, and even more preferably 1,000 MPa or more, 2,000 MPa or more, 3,000 MPa or more, or 4,000 MPa or more. The upper limit of the tensile modulus E2 of the adjacent layer 4 at 23°C is, for example, 15,000 MPa, preferably 10,000 MPa, more preferably 7,500 MPa or 5,000 MPa.

[0081] The tensile modulus E2 of the adjacent layer 4 at 23°C is determined based on the stress-strain curve. Details of the measurement are described in the examples.

[0082] The second peel-off liner is flexible.

[0083] 1.6.7 Relationship between adhesive layer 3, release liner 2, and adjacent layer 4 The adhesive layer 3, the release liner 2, and the adjacent layer 4 preferably satisfy the following formula [1], more preferably the following formula [2], more preferably the following formula [3], even more preferably the following formula [4], further preferably the following formula [5], further preferably the following formula [6], further preferably the following formula [7], and the following formula [8]. The upper limit of the left side in each of the above formulas is, for example, 100,000, and also, for example, 10,000.

[0084] E1 × E2 × (T1 + T2) / [T0 1 / 2 [×100,000] ≥ 500 [1]

[0085] E1 × E2 × (T1 + T2) / [T0 1 / 2 ×100,000] ≥ 1,000 [2]

[0086] E1 × E2 × (T1 + T2) / [T0 1 / 2 [×100,000] ≥ 2,500 [3]

[0087] E1 × E2 × (T1 + T2) / [T0 1 / 2 ×100,000]≧3,000 [4]

[0088] E1 × E2 × (T1 + T2) / [T0 1 / 2 ×100,000]≧4,000 [5]

[0089] E1 × E2 × (T1 + T2) / [T0 1 / 2 [×100,000] ≥ 5,000 [6]

[0090] E1 × E2 × (T1 + T2) / [T0 1 / 2 [×100,000] ≥ 6,000 [7]

[0091] E1 × E2 × (T1 + T2) / [T0 1 / 2 ×100,000] ≥ 7,000 [8]

[0092] E1: Tensile modulus of peel liner 2 at 23℃ (MPa) E2: Tensile modulus of adjacent layer 4 at 23℃ (MPa) T1: Thickness of release liner 2 (μm) T2: Thickness of adjacent layer 4 (μm) T0: Thickness of adhesive layer 3 (μm)

[0093] If the above formula is satisfied, then at least one of the following values ​​selected from the group consisting of the thickness T1 of the release liner 2, the tensile modulus E1 of the release liner 2, the thickness T2 of the adjacent layer 4, and the tensile modulus E2 of the adjacent layer 4 is large. Therefore, even if the adhesive layer 3 is thick, i.e., if the thickness T0 is large, the release liner 2 and / or adjacent layer 4 tend to become harder, so the amount of deflection D of the optical adhesive sheet 1 can be reduced.

[0094] Alternatively, if the above formula is satisfied, the adhesive layer 3 is thin. Therefore, even if at least one of the values ​​selected from the group consisting of the thickness T1 of the release liner 2, the tensile modulus E1 of the release liner 2, the thickness T2 of the adjacent layer 4, and the tensile modulus E2 of the adjacent layer 4 is small, the optical adhesive sheet 1 can maintain toughness. Therefore, the amount of deflection D of the optical adhesive sheet 1 can be reduced.

[0095] 1.7 Materials for each layer 1.7.1 Materials of Adhesive Layer 3 The adhesive layer 3 is a sheet-like pressure-sensitive adhesive formed from an adhesive composition. The adhesive composition includes at least a base polymer.

[0096] The base polymer is an adhesive component that provides tackiness in the adhesive layer 3. Examples of base polymers include acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate / vinyl chloride copolymers, modified polyolefin polymers, epoxy polymers, fluoropolymers, and rubber polymers. The base polymer may be used alone or in combination of two or more types. From the viewpoint of ensuring good transparency and tackiness in the adhesive layer 3, an acrylic polymer is preferably used as the base polymer.

[0097] Acrylic polymers are copolymers of monomer components containing (meth)acrylic acid esters in a proportion of 50% by mass or more. "(Meth)acrylic" means acrylic and / or methacrylic.

[0098] Preferably, an alkyl (meth)acrylate ester is used as the (meth)acrylic acid ester, and more preferably, an alkyl (meth)acrylate ester having 1 to 20 carbon atoms in the alkyl group. The alkyl (meth)acrylate ester may have a linear or branched alkyl group, or a cyclic alkyl group such as an alicyclic alkyl group.

[0099] Examples of alkyl (meth)acrylates having linear or branched alkyl groups include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, ( Examples include nonyl meth)acrylate, isononyl meth)acrylate, decyl meth)acrylate, isodecyl meth)acrylate, undecyl meth)acrylate, dodecyl meth)acrylate (i.e., lauryl acrylate), isotridecyl meth)acrylate, tetradecyl meth)acrylate, isotetradecyl meth)acrylate, pentadecyl meth)acrylate, cetyl meth)acrylate, heptadecyl meth)acrylate, octadecyl meth)acrylate, isooctadicyl meth)acrylate, and nonadecyl meth)acrylate.

[0100] Examples of alkyl (meth)acrylates having an alicyclic alkyl group include cycloalkyl (meth)acrylates, (meth)acrylates having a bicyclic aliphatic hydrocarbon ring, and (meth)acrylates having three or more aliphatic hydrocarbon rings. Examples of cycloalkyl (meth)acrylates include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. An example of a (meth)acrylate ester having a bicyclic aliphatic hydrocarbon ring is isobornyl (meth)acrylate. Examples of (meth)acrylic acid esters having three or more aliphatic hydrocarbon rings include dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0101] Preferably, an alkyl acrylate having an alkyl group with 3 to 15 carbon atoms is used as the (meth)acrylate, and more preferably, at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate, and dodecyl acrylate is used.

[0102] The proportion of alkyl (meth)acrylate in the monomer component is, from the viewpoint of appropriately exhibiting tackiness in the adhesive layer 3, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 92% by mass or more. The same proportion is, for example, 99% by mass or less.

[0103] The monomer component may include copolymerizable monomers that can copolymerize with alkyl (meth)acrylate esters. Examples of copolymerizable monomers include monomers having polar groups. Examples of polar group-containing monomers include monomers containing hydroxyl groups, monomers containing carboxyl groups, and monomers having nitrogen atom-containing rings. Polar group-containing monomers are useful for modifying acrylic polymers, such as introducing crosslinking sites into acrylic polymers and ensuring the cohesive strength of acrylic polymers.

[0104] Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Preferably, at least one selected from the group consisting of 4-hydroxybutyl acrylate and 2-hydroxyethyl acrylate is used as the hydroxyl group-containing monomer.

[0105] The proportion of hydroxyl group-containing monomers in the monomer components is, for example, 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring cohesive force in the adhesive layer 3. From the viewpoint of adjusting the polarity of the acrylic polymer (related to the compatibility between the various additive components in the adhesive layer 3 and the acrylic polymer), the proportion is preferably 20% by mass or less, and preferably 10% by mass or less.

[0106] Examples of monomers containing a carboxyl group include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0107] The proportion of carboxyl group-containing monomers in the monomer component is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 0.8% by mass or more, from the viewpoint of introducing a crosslinked structure into the acrylic polymer, ensuring cohesive force in the adhesive layer 3, and ensuring adhesion force to the adherend in the adhesive layer 3. The same proportion is preferably 10% by mass or less, and preferably 5% by mass or less, from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend by acid.

[0108] Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, and N-vinylisothiazole. Preferably, N-vinyl-2-pyrrolidone is used as the monomer having a nitrogen atom-containing ring.

[0109] The proportion of monomers having nitrogen atom-containing rings in the monomer components is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 1% by mass or more, from the viewpoint of ensuring cohesive force in the adhesive layer 3 and ensuring adhesion force to the adherend in the adhesive layer 3. The same proportion is preferably 30% by mass or less, and preferably 20% by mass or less, from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to the compatibility between various additive components in the adhesive layer 3 and the acrylic polymer).

[0110] The monomer component may contain other copolymerizable monomers. Examples of other copolymerizable monomers include acid anhydride monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic vinyl compounds. These other copolymerizable monomers may be used individually or in combination of two or more types.

[0111] The base polymer preferably has a crosslinked structure. Methods for introducing the crosslinked structure into the base polymer include the first method and the second method. These methods may be used in combination.

[0112] In the first method, a base polymer having a functional group that can react with a crosslinking agent and the crosslinking agent are blended into an adhesive composition, and the base polymer and the crosslinking agent are reacted in the adhesive layer 3. In the second method, a polyfunctional monomer is included in the monomer component that forms the base polymer, and a base polymer in which a branched structure (crosslinked structure) is introduced into the polymer chain is formed by polymerization of the monomer component.

[0113] Examples of crosslinking agents used in the first method include compounds that react with functional groups (such as hydroxyl groups and carboxyl groups) contained in the base polymer. Examples of such crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, carbodiimide crosslinking agents, and metal chelate crosslinking agents. The crosslinking agent may be used alone or in combination of two or more types. As crosslinking agents, isocyanate crosslinking agents, peroxide crosslinking agents, and epoxy crosslinking agents are preferably used because they have high reactivity with hydroxyl groups and carboxyl groups in the base polymer and facilitate the introduction of crosslinked structures.

[0114] Examples of isocyanate crosslinking agents include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethyl xylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, and polymethylene polyphenyl isocyanate. Derivatives of these isocyanates can also be used as isocyanate crosslinking agents. Examples of isocyanate derivatives include isocyanurate-modified and polyol-modified compounds. Examples of commercially available isocyanate crosslinking agents include Coronate L (trimethylolpropane adduct of tolylene diisocyanate, manufactured by Tosoh Corporation), Coronate HL (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Tosoh Corporation), Coronate HX (isocyanurate of hexamethylene diisocyanate, manufactured by Tosoh Corporation), Takenate D110N (trimethylolpropane adduct of xylylene diisocyanate, manufactured by Mitsui Chemicals Corporation), and Takenate 600 (1,3-bis(isocyanatomethyl)cyclohexane, manufactured by Mitsui Chemicals Corporation).

[0115] Examples of peroxide crosslinking agents include dibenzoyl peroxide, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, and t-butylperoxypivalate.

[0116] Examples of epoxy crosslinking agents include bisphenol A, epichlorohydrin-type epoxy resins, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, diamine glycidylamine, N,N,N',N'-tetraglycidyl-m-xylylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

[0117] From the viewpoint of ensuring the cohesive force of the adhesive layer 3, the amount of crosslinking agent is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, and more preferably 0.07 parts by mass or more, per 100 parts by mass of the base polymer. From the viewpoint of ensuring good tackiness in the adhesive layer 3, the amount of crosslinking agent per 100 parts by mass of the base polymer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, and more preferably 3 parts by mass or less.

[0118] In the second method, the monomer component may be polymerized in a single step or in multiple steps. The monomer component includes a polyfunctional monomer and other monomers for introducing a crosslinking structure. In the multi-step polymerization method, first, a monofunctional monomer to form a base polymer is polymerized (prepolymerization), thereby preparing a prepolymer composition containing a partial polymer (a mixture of a low-degree polymer and unreacted monomers). Next, a polyfunctional monomer is added to the prepolymer composition, and then the partial polymer and the polyfunctional monomer are polymerized (main polymerization).

[0119] Examples of polyfunctional monomers include polyfunctional (meth)acrylates containing two or more ethylenically unsaturated double bonds in one molecule. From the viewpoint of being able to introduce crosslinked structures by active energy ray polymerization (photopolymerization), polyfunctional acrylates are preferred as polyfunctional monomers.

[0120] Examples of polyfunctional (meth)acrylates include difunctional (meth)acrylates, trifunctional (meth)acrylates, and polyfunctional (meth)acrylates with four or more functions.

[0121] Examples of difunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, dicyclopentenyl diacrylate, di(meth)acryloyl isocyanurate, and alkylene oxide-modified bisphenol di(meth)acrylate.

[0122] Examples of trifunctional (meth)acrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tris(acryloyloxyethyl) isocyanurate.

[0123] Examples of polyfunctional (meth)acrylates with four or more functions include ditrimethylolpropanetetra(meth)acrylate, pentaerythritoltetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, alkyl-modified dipentaerythritol pentaacrylate, and dipentaerythritol hexa(meth)acrylate.

[0124] Acrylic polymers are obtained by polymerizing the above monomer components using known methods.

[0125] In polymerization, chain transfer agents may be used to adjust the molecular weight. Examples of chain transfer agents include α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and α-methylstyrene dimers.

[0126] The weight-average molecular weight of the base polymer is, for example, 100,000 or more, preferably 300,000 or more, and more preferably 500,000 or more, from the viewpoint of ensuring cohesive force in the adhesive layer 3. The weight-average molecular weight is, for example, 5 million or less, preferably 3 million or less, and more preferably 2 million or less. The weight-average molecular weight of the base polymer is measured by gel permeation chromatography (GPC) and calculated on a polystyrene basis.

[0127] The glass transition temperature (Tg) of the base polymer is, for example, 0°C or lower, preferably -10°C or lower, and more preferably -20°C or lower. Alternatively, the glass transition temperature may be, for example, -80°C or higher. The glass transition temperature (Tg) of the base polymer can be determined based on Fox's formula.

[0128] The adhesive composition may contain one or more oligomers in addition to the base polymer. When an acrylic polymer is used as the base polymer, an acrylic oligomer is preferably used as the oligomer. The acrylic oligomer is a copolymer of monomer components containing 50% by mass or more of alkyl (meth)acrylate, and has a weight-average molecular weight of, for example, 1,000 to 30,000.

[0129] The glass transition temperature of the acrylic oligomer is, for example, 60°C or higher, preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher. The glass transition temperature of the acrylic oligomer is, for example, 200°C or lower, preferably 180°C or lower, and preferably 160°C or lower. By using a low-Tg acrylic polymer (base polymer) with a crosslinked structure in combination with a high-Tg acrylic oligomer, the adhesive strength of the adhesive layer 3, especially the adhesive strength at high temperatures, can be increased. The glass transition temperature of the acrylic oligomer can be determined based on Fox's formula.

[0130] Acrylic oligomers with a glass transition temperature of 60°C or higher are preferably polymers of monomer components containing a (meth)acrylate (linear alkyl(meth)acrylate) having a chain-like alkyl group and an (meth)acrylate (alicyclic alkyl(meth)acrylate) having an alicyclic alkyl group. Specific examples of these (meth)acrylate alkyl esters include, for example, the above-mentioned (meth)acrylate alkyl esters used as monomer components in acrylic polymers.

[0131] As a linear alkyl (meth)acrylate, methyl methacrylate is preferred due to its high glass transition temperature and excellent compatibility with the base polymer. As a alicyclic alkyl (meth)acrylate, dicyclopentanyl acrylate is preferred.

[0132] The proportion of alicyclic alkyl (meth)acrylate in the monomer component of the acrylic oligomer is, for example, 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more. The same proportion is, for example, 90% by mass or less, preferably 80% by mass or less, and more preferably 70% by mass or less. The proportion of linear alkyl (meth)acrylate in the monomer component of the acrylic oligomer is, for example, 90% by mass or less, preferably 80% by mass or less, and more preferably 70% by mass or less. The same proportion is, for example, 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more.

[0133] The weight-average molecular weight of the acrylic oligomer is, for example, 1,000 or more, preferably 1,500 or more, and more preferably 2,000 or more. The molecular weight is, for example, 30,000 or less, preferably 10,000 or less, and more preferably 8,000 or less. Such a molecular weight range for the acrylic oligomer is preferable for ensuring the adhesive strength and adhesive retention strength of the adhesive layer 3.

[0134] Acrylic oligomers are obtained by polymerizing the monomer components of acrylic oligomers using known methods.

[0135] To sufficiently enhance the adhesive strength of the adhesive layer 3, the acrylic oligomer content in the adhesive layer 3 is, for example, 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the base polymer. On the other hand, from the viewpoint of ensuring the transparency of the adhesive layer 3, the acrylic oligomer content in the adhesive layer 3 is, for example, 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less, per 100 parts by mass of the base polymer. In the adhesive layer 3, if the acrylic oligomer content is too high, the haze tends to increase and the transparency tends to decrease due to a decrease in the compatibility of the acrylic oligomer.

[0136] The adhesive composition may contain a silane coupling agent. The content of the silane coupling agent in the adhesive composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, per 100 parts by mass of the base polymer. The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less.

[0137] The adhesive composition may contain other components as needed. Examples of other components include solvents, tackifiers, plasticizers, softeners, antioxidants, fillers, colorants, dyes, pigments, UV absorbers, antioxidants, infrared absorbers, surfactants, catalysts, particles, UV-curable monomers, UV-curable oligomers, UV-curable resins, photopolymerization initiators, metals, fibers, conductive materials, and antistatic agents.

[0138] 1.7.2 Materials for release liner 2 Flexible materials can be used as the material for the peel-off liner 2. Specifically, plastics can be used as the peel-off liner 2. Examples of plastics include polyester, polyolefins, polyimides, polyether ether ketone (PEEK), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polymethyl methacrylate (PMMA) and other acrylic resins, polycarbonate, triacetylcellulose (TAC), polysulfone, polyarylate, polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), fully aromatic polyamide (aramid), polyvinyl chloride (PVC), polyvinyl acetate, polyphenylene sulfide (PPS), fluororesins, cyclic olefin polymers, cycloolefins, and polyurethanes.

[0139] From the viewpoint of increasing the tensile modulus E1, polyester is preferred as the material for the peel-off liner 2.

[0140] A release layer (not shown) may be formed on one side of the peel liner 2 in the thickness direction. The release layer is a layer formed by a release treatment with a release agent on one side of the peel liner 2 in the thickness direction. Examples of release treatments include silicone release treatment, long-chain alkyl acrylate release treatment, and fluorine release treatment. That is, examples of release layers include silicone release layer, long-chain alkyl acrylate release layer, and fluorine release layer. Preferably, the release layer is a silicone release layer from the viewpoint of ease of adjusting the peeling force from the adhesive layer 3.

[0141] 1.7.3 Materials of adjacent layer 4 Flexible materials can be used as the material for the adjacent layer 4. Specifically, plastics can be used as the adjacent layer 4. Examples of plastics include those exemplified in the release liner 2. A release layer (not shown) may be formed on the other side of the adjacent layer 4 in the thickness direction.

[0142] 1.8 Method for manufacturing optical adhesive sheet 1 The manufacturing method for the optical adhesive sheet 1 will be explained with reference to Figures 3A to 3D. In this manufacturing method, first a laminate 51 is made (see Figure 3A), then the adhesive layer 3 is shaped (see Figure 3B), then unnecessary parts 53 are removed (see Figure 3C), then the release liner 2 is shaped (see Figure 3D), and then the third release liner 5 is replaced with the adjacent layer 4 (see Figure 3D).

[0143] As shown in Figure 3A, the laminate 51 has, for example, a long sheet shape. The laminate 51 comprises a release liner 2, an adhesive layer 3, and a third release liner 5, arranged in order toward one side in the thickness direction.

[0144] The peeling force of the third peel liner 5 is small. Specifically, the peeling force required to peel the third peel liner 5 from the adhesive layer 3 is smaller than the peeling force required to peel the peel liner 2 from the adhesive layer 3. The surface of the third peel liner 5 is subjected to, for example, a known peeling treatment. The third peel liner 5 also serves as a protective material that protects one side of the adhesive layer 3 (coating film 31) during the manufacturing process.

[0145] To produce the laminate 51, for example, a release liner 2 is prepared, then an adhesive composition is applied to one side of the release liner 2 in the thickness direction to form a coating film 31, then a third release liner 5 is placed on one side of the coating film 31 in the thickness direction, and then the coating film 31 is dried or irradiated with light.

[0146] Methods for shaping the adhesive layer 3 include, for example, laser irradiation and cutting with a cutting blade. A laser is irradiated from one side in the thickness direction toward the laminate 51, or a blade is inserted toward the laminate 51.

[0147] As a method for shaping the adhesive layer 3, laser irradiation is preferred from the viewpoint of making the recesses 25 shallower.

[0148] Examples of lasers include gas lasers, solid-state lasers, and semiconductor lasers. Examples of gas lasers include excimer lasers and CO2 lasers (10.6 μm).

[0149] Through the external shaping process described above, the adhesive layer 3 is shaped to have the length L described above. At the same time, the third release liner 5 is also shaped to have the same shape and size as the adhesive layer 3. As a result, notches 26 are formed in the adhesive layer 3 and the third release liner 5. The adhesive layer 3 has the length L described above.

[0150] At the same time, a recess 25 is unintentionally (inevitably) formed on one side of the peel liner 2 in the thickness direction. The recess 25 is the bottom of the cut 26.

[0151] As shown in Figure 3C, the unnecessary portion 53 is removed. The unnecessary portion 53 is the part of the adhesive layer 3 and the third peel liner 5 located outside the cut 26. One method for removing the unnecessary portion 53 is removal using a winding roll.

[0152] As shown in Figure 3D, the third peel liner 5 is replaced with the adjacent layer 4, and the peel liner 2 is shaped externally.

[0153] In replacing the adjacent layer 4, as shown by the dashed line in Figure 3C, the third release liner 5 is peeled off from one side of the adhesive layer 3 in the thickness direction, and then the adjacent layer 4 is placed on one side of the adhesive layer 3.

[0154] The long release liner 2 is shaped to be larger than the adhesive layer 3 and to encompass the adhesive layer 3. Methods for shaping the release liner 2 include laser irradiation and cutting with a cutting blade.

[0155] Subsequently, if necessary, the adhesive layer 3 is aged. The aging temperature is, for example, 50°C to 100°C. The aging time is 30 minutes to 3 days.

[0156] This results in the manufacture of an optical adhesive sheet 1 comprising a release liner 2, an adhesive layer 3, and an adjacent layer 4.

[0157] As shown in Figure 4, the adhesive layer 3 of the optical adhesive sheet 1 is attached to the image display device component 11.

[0158] The image display device component 11 is oriented in the planar direction. The image display device component 11 has a sheet shape. The image display device component 11 is an element provided in the image display device 20 (see Figure 5). Specifically, examples of the image display device component 11 include an optical substrate, a pixel panel, a polarizing plate, a touch panel, and a cover film. Examples of optical substrates include glass film (ultra-thin glass, UTG), polyester film, polyolefin film, and polyimide film. Examples of polyester films include polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film. Examples of polyolefin films include polyethylene film, polypropylene film, and cycloolefin film. Examples of pixel panels include LCD panels, OLED panels, miniLEDs, and μLED panels.

[0159] The image display device component 11 is single-layer or multi-layer. As shown by the dashed line in Figure 4, for example, the image display device component 11 comprises a first layer 111 and a second layer 112 in order toward one side in the thickness direction. Examples of the first layer 111 include an optical substrate and a polarizing plate. Examples of the second layer 112 include a cover film.

[0160] The image display device component 11 is another example of the adjacent layer 4. The optical adhesive sheet 1 comprises a release liner 2, an adhesive layer 3, and the image display device component 11 in order toward one side in the thickness direction.

[0161] The peripheral edge of the image display device component 11 coincides with the peripheral edge of the adhesive layer 3.

[0162] Furthermore, an undercoat layer may be formed on the other side of the image display device member 11 in the thickness direction, as shown in the figure. In this case, the image display device member 11 is attached (formed) to one side of the adhesive layer 3 in the thickness direction via the undercoat layer.

[0163] To manufacture the optical adhesive sheet 1 shown in Figure 4, the third release liner 5 is peeled off from the adhesive layer 3 as shown by the dashed line in Figure 3C, and then the image display device member 11 is attached to one side of the adhesive layer 3 in the thickness direction, as shown in Figure 4.

[0164] 1.9 Image display device 20 As shown in Figure 5, the adhesive layer 3 is further attached to other image display device components 12. Specifically, the image display device 20 comprises the adhesive layer 3 and a pair of image display device components 11 and 12.

[0165] The adhesive layer 3 and image display device component 11 in Figure 5 are the same as the adhesive layer 3 and image display device component 11 in the optical adhesive sheet 1 shown in Figure 4.

[0166] The image display component 12 is positioned on the opposite side of the image display component 11 from the adhesive layer 3 in the thickness direction. Specifically, the image display component 12 is positioned on the other side of the adhesive layer 3 in the thickness direction. A primer layer, as shown in the figure, may be formed on one side of the image display component 12 in the thickness direction. In this case, the image display component 12 is attached to (formed upon) the adhesive layer 3 via the primer layer. Examples of the image display component 12 include the elements exemplified in the image display component 11 described above.

[0167] The peripheral edge of the image display device member 12 coincides with the peripheral edge of the adhesive layer 3 when viewed in the thickness direction. In this embodiment, the peripheral end surfaces of the pair of image display device members 11 and 12 and the peripheral end surface of the adhesive layer 3 are flush.

[0168] 2. Effects of one embodiment In this optical adhesive sheet 1, the maximum length L of the adhesive layer 3 is 200 mm or more, so the adhesive layer 3 can be used to attach components of large image display devices such as tablets.

[0169] Furthermore, even if the length L mentioned above is 200 mm or more, in this optical adhesive sheet 1, the release liner 2 is larger than the adhesive layer 3 when viewed in the thickness direction and encloses the adhesive layer 3, so the release liner 2 prevents the edges of the adhesive layer 3 from protruding. Therefore, contamination of the surrounding area by the adhesive layer 3 can be suppressed.

[0170] Furthermore, since the overhang of the adhesive layer 3 at the edges of this optical adhesive sheet 1 is suppressed, it offers excellent handling characteristics.

[0171] Furthermore, in this optical adhesive sheet 1, the overhang of the adhesive layer 3 at the edges is suppressed, which reduces adhesive chipping and improves the adhesive reliability of the adhesive layer 3.

[0172] If the amount of deflection D of the optical adhesive sheet 1 is 7 mm or less, the optical adhesive sheet 1 will have even better handling properties.

[0173] Furthermore, in this optical adhesive sheet 1, the area P, which is the product of the offset amount OL of the release liner 2 and the thickness T1 of the release liner 2, is 90 × 10 -8 m 2 In the above case, it is possible to suppress the adhesive layer 3 from lifting away from the peeling liner 2.

[0174] For more details, the area P is 90 × 10 -8 m 2 In the above case, even if the thickness T1 of the peel-off liner 2 is thin, the offset amount OL of the peel-off liner 2 becomes large. Therefore, even if the offset portion 21 deforms, this deformation is less likely to affect the adhesive layer 3. As a result, lifting, which is the unintentional separation of the adhesive layer 3 from the peel-off liner 2, can be suppressed.

[0175] Alternatively, the area P is 90 × 10 -8 m 2 In the above case, even if the offset amount OL of the peeling liner 2 is small, the peeling liner 2 is thick. In this case, even if the offset portion 21 comes into contact with the conveying machine, deformation of the peeling liner 2 is suppressed. Therefore, lifting of the adhesive layer 3 can be suppressed.

[0176] Furthermore, in this optical adhesive sheet 1, if the above-described formula [3] is satisfied, at least one of the group consisting of the thickness T1 of the release liner 2, the tensile modulus E1 of the release liner 2, the thickness T2 of the adjacent layer 4, and the tensile modulus E2 of the adjacent layer 4 is large. Therefore, even if the adhesive layer 3 is thick, the release liner 2 and / or adjacent layer 4 tend to become hard, so the above-described amount of deflection D of the optical adhesive sheet 1 can be reduced.

[0177] Alternatively, if the above-mentioned formula [3] is satisfied, the adhesive layer 3 is thin. Therefore, even if at least one of the group consisting of the thickness T1 of the release liner 2, the tensile modulus E1 of the release liner 2, the thickness T2 of the adjacent layer 4, and the tensile modulus E2 of the adjacent layer 4 is small, the optical adhesive sheet 1 can maintain toughness, and thus the above-mentioned amount of deflection D of the optical adhesive sheet 1 can be reduced.

[0178] Furthermore, in this optical adhesive sheet 1, the second release liner 4A, which is an example of an adjacent layer 4, is larger than the adhesive layer 3 when viewed in the thickness direction and encloses the adhesive layer 3. Therefore, the protrusion of the edges of the adhesive layer 3 is further suppressed by the second release liner 4A, resulting in even better handling of the optical adhesive sheet 1.

[0179] Furthermore, in this optical adhesive sheet 1, the area P2, which is the product of the second offset amount OL2 of the second release liner 4A, which is an example of an adjacent layer 4, and the thickness T2 of the second release liner 4A, is 90 × 10 -8 m 2 In the above case, it is possible to suppress the adhesive layer 3 from lifting away from the second peel liner 4A.

[0180] For more details, area P2 is 90 × 10 -8 m 2 In the above case, the second offset amount OL2 of the second peel liner 4A is large, and even if the second offset portion 41 deforms, such deformation is less likely to affect the adhesive layer 3. Therefore, lifting, which is the unintentional separation of the adhesive layer 3 from the second peel liner 4A, can be suppressed.

[0181] Alternatively, area P2 is 90 × 10 -8 m 2 In the above case, the second peel liner 4A is thick. In this case, even if the offset portion 21 comes into contact with the conveying machine, deformation of the second peel liner 4A is suppressed. Therefore, lifting of the adhesive layer 3 can be suppressed.

[0182] Furthermore, in this optical adhesive sheet 1, if the depth of the recess 25 is 30 μm or less, it is possible to suppress the cutting of the release liner 2 starting from the recess 25.

[0183] Furthermore, in this optical adhesive sheet 1, if the indentation hardness H of the adhesive layer 3 at 23°C is 10 kPa or less, the adhesive layer 3 is suitably used for attaching components to an image display device that can be repeatedly folded (foldable).

[0184] Furthermore, in this optical adhesive sheet 1, if the shear storage modulus G' of the adhesive layer 3 at 25°C is 100 kPa or less, the adhesive layer 3 is suitably used for attaching components to a foldable image display device.

[0185] 3. Variations In the following modifications, the same reference numerals are used for components and processes as in the above-described embodiment, and their detailed descriptions are omitted. Furthermore, each modification can achieve the same effects and advantages as the first embodiment, unless otherwise specified. Moreover, the first embodiment and its modifications can be combined as appropriate.

[0186] As shown in Figure 6, the modified optical adhesive sheet 1 comprises a release liner 2 and an adhesive layer 3 in order toward one side in the thickness direction. The optical adhesive sheet 1 does not have an adjacent layer 4. The modified optical adhesive sheet 1 comprises only a release liner 2 and an adhesive layer 3.

[0187] To manufacture the modified optical adhesive sheet 1, the third release liner 5, shown by the dashed line in Figure 3C, is peeled off from the adhesive layer 3.

[0188] Comparing one embodiment with its modifications, the first embodiment is preferred. In the first embodiment, the adjacent layer 4 can suppress contamination of one side of the adhesive layer 3 in the thickness direction.

[0189] Although not shown in the diagram, the adjacent layer 4 has the same size when viewed in the thickness direction. In this modified example, the circumferential surface of the adjacent layer 4 is flush with the circumferential surface of the adhesive layer 3. [Examples]

[0190] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to these examples. Furthermore, specific numerical values ​​such as blending ratios (content ratios), physical properties, and parameters used in the following description may be replaced with the corresponding upper limits (numbers defined as "less than or equal to" or "less than") or lower limits (numbers defined as "greater than or equal to" or "greater than or equal to") of the blending ratios (content ratios), physical properties, and parameters described in the "Modes for Carrying Out the Invention" above.

[0191] (Preparation of adhesive compositions A to E) Preparation example A

[0192] 60 parts by mass of dicyclopentanyl methacrylate (DCPMA) and 40 parts by mass of methyl methacrylate (MMA) were mixed as monomer components, 3.5 parts by mass of α-thioglycerol was added as a chain transfer agent, and 100 parts by mass of toluene was added as a polymerization solvent. The mixture was stirred at 70°C for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator, and the mixture was reacted at 70°C for 2 hours, then the temperature was raised to 80°C and the reaction was continued for 2 hours. After that, the reaction mixture was heated to 130°C to dry and remove toluene and unreacted monomers, yielding a solid acrylic oligomer (oligomer (1)). The weight-average molecular weight of oligomer (1) was 5,100, and the glass transition temperature (Tg) was 130°C.

[0193] Separately, 40 parts by mass of lauryl acrylate (LA), 46 parts by mass of 2-ethylhexyl acrylate (2EHA), 7 parts by mass of 4-hydroxybutyl acrylate (4HBA), and 7 parts by mass of N-vinyl-2-pyrrolidone (NVP) were added as monomer components for prepolymer formation, and 0.015 parts by mass of BASF's "Irgacure 184" was added as a photopolymerization initiator. Polymerization was carried out by irradiation with ultraviolet light to obtain prepolymer composition A (polymerization rate of approximately 10%).

[0194] Subsequently, 0.07 parts by mass of 1,6-hexanediol diacrylate (HDDA), 5 parts by mass of oligomer (1), and 0.3 parts by mass of silane coupling agent (Shin-Etsu Chemical's "KBM403") were added to 100 parts by mass of prepolymer composition A as post-addition components, and these were then uniformly mixed to prepare adhesive composition A.

[0195] Preparation example B As monomer components for forming the prepolymer, 30 parts by mass of lauryl acrylate (LA), 65 parts by mass of 2-ethylhexyl acrylate (2EHA), 8 parts by mass of 4-hydroxybutyl acrylate (4HBA), and 4 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 0.015 parts by mass of BASF's "Irgacure 184" as a photopolymerization initiator were blended, and polymerization was carried out by irradiation with ultraviolet light to obtain prepolymer composition B (polymerization rate approximately 10%).

[0196] Then, to 100 parts by mass of prepolymer composition B, 0.07 parts by mass of 1,6-hexanediol diacrylate (HDDA), 5 parts by mass of the above-mentioned oligomer (1), and 0.3 parts by mass of silane coupling agent (Shin-Etsu Chemical's "KBM403") were added as post-addition components, and these were then uniformly mixed to prepare adhesive composition B.

[0197] Preparation example C In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 9 parts by mass of lauryl acrylate (LA), 68 parts by mass of 2-ethylhexyl acrylate (2EHA), 21 parts by mass of n-butyl acrylate (BA), 1 part by mass of 4-hydroxybutyl acrylate (4HBA), 1 part by mass of N-vinyl-2-pyrrolidone (NVP), and 0.1 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator were added. Ethyl acetate was then added to bring the total concentration of these components to 47% by weight. The system was purged with nitrogen over 1 hour while gently stirring, and polymerization was carried out for 6 hours while maintaining the temperature of the solution in the flask at around 56°C. After the reaction was complete, ethyl acetate was added to adjust the polymer concentration to 24% by weight, obtaining a solution of acrylic polymer C. The weight-average molecular weight of acrylic polymer C was 2,000,000.

[0198] Next, 100 parts by mass of acrylic polymer C, 0.25 parts by mass of peroxide (Nipper BMT-40SV, manufactured by Nippon Oil & Fats Co., Ltd.) as a crosslinking agent, 3 parts by mass of the above-mentioned oligomer (1), 0.3 parts by mass of Irganox 1010 (manufactured by BASF) as an antioxidant, and 0.01 parts by mass of Narsem ferric (manufactured by Nippon Chemical Industrial Co., Ltd.) as a catalyst were mixed and stirred thoroughly, and then diluted with ethyl acetate so that the total solid content was 21% by weight to prepare adhesive composition C.

[0199] Preparation example D A monomer mixture containing 99 parts of butyl acrylate (BA) and 1 part of 4-hydroxybutyl acrylate (HBA) was charged into a reaction vessel equipped with a condenser, a nitrogen inlet tube, a thermometer, and a stirrer. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile was added to 100 parts of the monomer mixture as a polymerization initiator along with 100 parts of ethyl acetate. After introducing nitrogen gas and purging the mixture with nitrogen while gently stirring, the polymerization reaction was carried out for 8 hours while maintaining the liquid temperature in the flask at around 55°C to prepare a solution of an acrylic polymer with a weight-average molecular weight of 1.8 million (solid content concentration 30% by weight). Adhesive composition D was prepared by blending 0.3 parts of a radical generator (benzoyl peroxide, trade name Niper BMT manufactured by Nippon Oil & Fats Co., Ltd.), 0.1 parts of an isocyanate crosslinking agent (trade name Takenate D110N manufactured by Mitsui Chemicals, Inc.), and 0.1 parts of a silane coupling agent (KBM403 manufactured by Shin-Etsu Chemical Co., Ltd.) with 100 parts of the solid content of the acrylic polymer (1) solution described above.

[0200] Preparation example E 63 parts by mass of 2-ethylhexyl acrylate (2EHA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), 9 parts by mass of methyl methacrylate (MMA), 13 parts by mass of 2-hydroxyethyl acrylate (HEA) as monomer components, 0.2 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 133 parts by mass of ethyl acetate as a polymerization solvent were placed in a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen from the polymerization system in this way, the temperature was raised to 65°C and the reaction was allowed to proceed for 10 hours. Then, ethyl acetate was added to obtain a solution of acrylic polymer (f) with a solid content of 30% by weight.

[0201] Next, an isocyanate-based crosslinking agent (product name "Takenate D110N", manufactured by Mitsui Chemicals, Inc.) was added to a solution of acrylic polymer (a) in an amount of 1 part by mass on a solid content basis per 100 parts by mass of acrylic polymer (a) (solid content) to prepare adhesive composition E.

[0202] <Preparation of the peeling liner 2 and adjacent layer 4> The peel-off liner 2 and adjacent layer 4 described in Table 1 below were prepared. Table 1 lists the materials and manufacturers of the peel-off liner 2 and adjacent layer 4.

[0203] (Example of forming an adhesive layer 3 from adhesive composition A) (Examples 1-16, 20-23, 25-29)

[0204] (Example 1) A release liner 2 made of MRF with a thickness T1 of 25 μm and a third release liner 5 with a thickness of 75 μm were prepared. The third release liner 5 is a PET film (Mitsubishi Chemical's "Diafoil MRE75") with one side treated with silicone release. Both the release liner 2 and the third release liner 5 have an elongated shape.

[0205] Adhesive composition A was applied to one side of the release liner 2 to form a coating film 31 with a drying thickness of 25 μm. The third release liner 5 was then attached to this coating film 31. As a result, a laminate 51 was created, comprising the release liner 2, the coating film 31, and the third release liner 5 in that order, as shown in Figure 3A. The laminate 51 was subjected to an irradiation intensity of 5 mW / cm² on the irradiation surface directly beneath the lamp, from one side of the laminate 51 in the thickness direction. 2 A black light, positioned to achieve the desired effect, was used to irradiate the material with ultraviolet light and perform photocuring, thereby creating an adhesive layer 3 with a thickness of 25 μm.

[0206] Next, as shown in Figure 3B, the adhesive layer 3 of the laminate 51 was processed externally. Specifically, by irradiating the laminate 51 with a CO2 laser in the thickness direction from the third peel liner 5 side, cuts 26 were formed in both the adhesive layer 3 and the third peel liner 5. This cut the adhesive layer 3 and the third peel liner 5 in the thickness direction. A recess 25 with a depth of 20 μm was formed on one side of the peel liner 2. The longitudinal length L of the adhesive layer 3 was 250 mm.

[0207] Next, as shown in Figure 3C, the outer portions of the cuts 26 in the adhesive layer 3 and the third release liner 5 were wound up using a winding roll.

[0208] Subsequently, the peel liner 2 was shaped as shown in Figure 3D. The length L1 of the peel liner 2 was 260 mm. The offset amount OL of the peel liner 2 was 5 mm.

[0209] Subsequently, an adjacent layer 4 with a length L2 of 250 mm was laminated to one side of the adhesive layer 3. The peripheral surface of the adjacent layer 4 was flush with the peripheral surface of the adhesive layer 3.

[0210] The laminate was then aged in a 50°C oven for one day.

[0211] This resulted in the manufacture of an optical adhesive sheet 1 comprising a release liner 2, an adhesive layer 3, and an adjacent layer 4 in that order.

[0212] (Examples 2-16, 20-23, 25-29) An optical adhesive sheet 1 was manufactured in the same manner as in Example 1. However, the type, thickness, offset amount, and second offset amount of the release liner 2, adhesive layer 3, and adjacent layer 4 were changed according to the descriptions in Tables 2 and 3.

[0213] (Example of forming an adhesive layer 3 from adhesive composition B and adhesive composition E) (Example 17) An optical adhesive sheet 1 was manufactured in the same manner as in Example 1. However, adhesive composition B was used instead of adhesive composition A, as described in Table 2.

[0214] (Example 18) An optical adhesive sheet 1 was manufactured in the same manner as in Example 1. However, adhesive composition C was used instead of adhesive composition A, as described in Table 2. Furthermore, thermocuring was used instead of photocuring in the preparation of the adhesive layer 3. Specifically, the coating film 31 on the release liner 2, before the placement of the third release liner 5, was dried at 130°C for 3 minutes to form the adhesive layer 3. Aging was carried out in the same manner as in Example 1.

[0215] (Example 19) An optical adhesive sheet 1 was manufactured in the same manner as in Example 1. However, adhesive composition D was used instead of adhesive composition A, as described in Table 2. Furthermore, thermocuring was used instead of photocuring in the preparation of the adhesive layer 3. Specifically, the coating film 31 on the release liner 2, before the placement of the third release liner 5, was dried at 130°C for 3 minutes to form the adhesive layer 3. Aging was carried out in the same manner as in Example 1.

[0216] (Example of forming an adhesive layer 3 from adhesive composition E) (Example 24) An optical adhesive sheet 1 was manufactured in the same manner as in Example 1. However, adhesive composition E was used instead of adhesive composition A, as described in Table 3. Furthermore, thermocuring was used instead of photocuring in the preparation of the adhesive layer 3. Specifically, the coating film 31 on the release liner 2, before the placement of the third release liner 5, was dried at 130°C for 3 minutes to form the adhesive layer 3. Aging was carried out in the same manner as in Example 1.

[0217] (evaluation) The following items were evaluated for each optical adhesive sheet 1 of Examples 1 to 29. The results are shown in Tables 2 and 3.

[0218] (Offset amount OL, second offset amount OL2) The offset amount OL of the release liner 2 in the optical adhesive sheet 1 and the second offset amount OL2 of the adjacent layer 4 were measured.

[0219] (Thickness T0, T1, T2) The thickness T0 of the adhesive layer 3, the thickness T1 of the release liner 2, and the thickness T2 of the adjacent layer 4 in the optical adhesive sheet 1 were measured.

[0220] The thickness T1 of the peel liner 2 was determined as the average thickness (μm) at three points in the offset portion. The thickness T2 of the adjacent layer 4 was determined as the average thickness (μm) at three points in the offset portion.

[0221] Next, the area P of the peeled liner 2 was calculated as the product of the offset amount OL and the thickness T1. The area P2 of the adjacent layer 4 was calculated as the product of the second offset amount OL2 and the thickness T2.

[0222] (Deflection amount D) The amount of deflection D of the optical adhesive sheet 1 was determined by conducting the following deflection test.

[0223] Deflection Test: A sample 100 was prepared by shaping an optical adhesive sheet 1 to a length of 100 mm and a width of mm. As shown in Figure 2, a stand 105 with a top surface and a height of 50 mm or more was prepared. The surface of a 50 mm long first portion 101, including one longitudinal edge of the sample, was fixed to the top surface. A 200 g weight 106 made of glass plate was placed on the top surface of the first portion 101. A 50 mm long second portion 102, including the other longitudinal edge of the sample, was made to protrude laterally from one longitudinal edge of the top surface. The sample was then left at 23°C for 5 minutes. After that, the amount of movement of the protruding edge of the sample downward from the top surface was obtained. Separately, the back surface of the first portion 101 was fixed to the top surface and its movement was obtained. The average of the two movement amounts was determined as the deflection amount D.

[0224] (Adhesive layer 3's indentation hardness H) In the optical adhesive sheet 1, the release liner 2 or adjacent layer 4 was peeled off from the adhesive layer 3. Next, an indentation test in accordance with ISO 14577 was performed on the surface of the adhesive layer 3 using a triboindenter (Hysitron) at a temperature of 23°C. In the indentation test, an indenter with a diameter of 20 μm was used, and the indenter was pressed into the adhesive layer 3 to an indentation depth of 2.5 μm. The indentation hardness H of the adhesive layer 3 was calculated from the maximum vertical load and contact area.

[0225] (Tensile modulus of elasticity of peeling liner 2: E1, tensile modulus of elasticity of adjacent layer 4: E2) This document describes the measurement of the tensile modulus E1 of the release liner 2 and the tensile modulus E2 of the adjacent layer 4 in the optical adhesive sheet 1.

[0226] First, the central part of the optical adhesive sheet 1 was shaped to a size of 10 mm in width and 150 mm in length to prepare a sample. The sample did not have either the offset portion 21 or the second offset portion 41. The peripheral edges of the release liner 2, adhesive layer 3, and adjacent layer 4 in the sample were flush.

[0227] Next, either the release liner 2 or the adjacent layer 4 was peeled off from the adhesive layer 3. This prepared a sample consisting of one of the layers and a laminated sample consisting of the other layer and the adhesive layer 3.

[0228] The sample was fixed to a tensile testing machine with a grip distance of 100 mm. The sample was stretched at a speed of 200 mm / min, and a stress-strain curve was created. The tensile modulus of the delaminate liner or adjacent layer 4 alone was calculated by determining the slope of the stress-strain curve at two points where the strain was 0.05% and 0.25%.

[0229] The tensile modulus E2 of the laminated sample was calculated in the same manner as the calculation of the tensile modulus E1 of the sample described above. In the tensile test of the laminated sample, the tensile modulus of the adhesive layer 3 (for reference, the storage shear modulus G' of the adhesive layer 3 at 25°C in Example 1 was 0.03 MPa) was considered negligible because it was very small compared to the tensile modulus E1 of only the adjacent layer 4, and the tensile modulus of only the peel liner 2 or the adjacent layer 4 was calculated based on the tensile test of the laminated sample described above.

[0230] (Relationship between the thickness T0 of the adhesive layer 3, the thickness T1 and tensile modulus E1 of the release liner 2, and the thickness T2 and tensile modulus E2 of the adjacent layer 4)

[0231] The thickness T0 of the adhesive layer 3, the thickness T1 and tensile modulus E1 of the release liner 2, and the thickness T2 and tensile modulus E2 of the adjacent layer 4 are given by the left side of the above equation (E1 × E2 × (T1 + T2) / [T0 1 / 2 It was substituted into [×100,000].

[0232] (Shear storage modulus G' of adhesive layer 3) The shear storage modulus G' of the adhesive layer 3 was determined by dynamic viscoelasticity measurement.

[0233] First, the required number of measurement samples were prepared for each of the 3 adhesive layers. Specifically, multiple sheet pieces cut from the 3 adhesive layer were first attached to create a sample sheet with a thickness of approximately 1.5 mm. Next, this sheet was punched out to obtain cylindrical pellets (7.9 mm in diameter) which were to be used as measurement samples.

[0234] Then, dynamic viscoelasticity measurements were performed on the sample using a dynamic viscoelasticity measuring device (product name "Advanced Rheometric Expansion System (ARES)", manufactured by Rheometric Scientific) after fixing it to a 7.9 mm diameter parallel plate jig. For the dynamic viscoelasticity measurement, the measurement mode was set to shear mode, the measurement temperature range to -40°C to 100°C, the heating rate to 5°C / min, and the frequency to 1 Hz. The shear storage modulus at 25°C was read from the measurement results.

[0235] [Table 1]

[0236] [Table 2]

[0237] [Table 3] [Explanation of Symbols]

[0238] 1 Optical adhesive sheet 2. Peel-off liner 3 Adhesive layer 4. Adjacent Layers 4A Second Detachable Liner 10 Optical adhesive sheets 11 Components for image display devices 12 Components for image display devices 21 Offset portion 25 recesses 41 Second offset portion 100 samples 101 Part 1 102 Part 2 105 units D Deflection E1 Tensile modulus (peelable liner) E2 Tensile modulus (adjacent layer) G' Shear storage modulus (adhesive layer) H: Indentation hardness (adhesive layer) OL offset amount (peel-off liner) OL2 Second offset amount (adjacent layer) P stack (peel-off liner) P2 stack (adjacent layer)

Claims

1. The release liner and the adhesive layer are arranged sequentially on one side in the thickness direction. The maximum length L of the adhesive layer in the orthogonal direction perpendicular to the thickness direction is 200 mm or more. The aforementioned release liner, when viewed in the thickness direction, is larger than the adhesive layer and encloses the adhesive layer. The following further comprises adjacent layers adjacent to the adhesive layer on the opposite side of the release liner in the thickness direction, The aforementioned release liner, the adhesive layer, and the adjacent layer are optical adhesive sheets that satisfy the following formula [X]. E1 × E2 × (T1 + T2) / [T0] １／２ ×100,000]≧1,000 [X] E1: Tensile modulus (MPa) of the peel liner at 23°C E2: Tensile modulus (MPa) of the adjacent layer at 23°C T1: Thickness of the release liner (μm) T2: Thickness of the adjacent layer (μm) T0: Thickness of the adhesive layer (μm)

2. The optical adhesive sheet according to claim 1, wherein the amount of deflection D measured in the deflection test described below is 7 mm or less. Bending test: Prepare a sample by shaping the optical adhesive sheet to a length of 100 mm and a width of 25 mm. Prepare a stand with a top surface and a height of 50 mm or more. A first portion of the sample, 50 mm in length and including one longitudinal edge, is fixed to the upper surface, and a second portion, 50 mm in length and including the other longitudinal edge of the sample, is allowed to protrude laterally from one end of the upper surface. The sample is then left at 23°C for 5 minutes. After that, the amount of movement of the protruding edge of the sample downward from the upper surface is determined as the amount of deflection D.

3. The release liner has a shape similar to the adhesive layer, The area P, which is the product of the offset amount and thickness of the peeling liner as defined below, is 90 × 10 －８ I understand ２ The optical adhesive sheet according to claim 1 or claim 2. The offset amount: The length (mm) of the offset portion that is offset from the adhesive layer in the release liner when viewed in the thickness direction. The aforementioned thickness: The average thickness (μm) at the three points in the offset portion.

4. The optical adhesive sheet according to claim 2, wherein the release liner, the adhesive layer, and the adjacent layer satisfy the following formula [1]. E1 × E2 × (T1 + T2) / [T0] １／２ ×100,000]≧2,500 ［１］ E1: Tensile modulus (MPa) of the peel liner at 23°C E2: Tensile modulus (MPa) of the adjacent layer at 23°C T1: Thickness of the release liner (μm) T2: Thickness of the adjacent layer (μm) T0: Thickness of the adhesive layer (μm)

5. The optical adhesive sheet according to claim 4, wherein the adjacent layer is a second release liner.

6. The optical adhesive sheet according to claim 5, wherein the second release liner is larger than the adhesive layer when viewed in the thickness direction and encloses the adhesive layer.

7. The second release liner has a shape similar to the adhesive layer, The area P2, which is the product of the offset amount and thickness of the second peel liner as defined below, is 90 × 10 －８ I understand ２ The optical adhesive sheet according to claim 6. The second offset amount: The length (mm) of the second offset portion that is offset from the adhesive layer in the second release liner when viewed in the thickness direction. The aforementioned thickness: The average thickness (μm) at the three points in the second offset portion.

8. The optical adhesive sheet according to claim 4, wherein the adjacent layer is a component for an image display device.

9. The optical adhesive sheet according to claim 8, wherein the peripheral edge of the image display device member coincides with the peripheral edge of the adhesive layer when viewed in the thickness direction.

10. One side of the release liner in the thickness direction has a recess around the peripheral edge of the adhesive layer that is recessed toward the other side in the thickness direction, The optical adhesive sheet according to any one of claims 1 to 9, wherein the depth of the recess is 30 μm or less.

11. The optical adhesive sheet according to any one of claims 1 to 10, wherein the indentation hardness H of the adhesive layer at 23°C is 10 kPa or less.

12. The optical adhesive sheet according to any one of claims 1 to 11, wherein the shear storage modulus G' of the adhesive layer at 25°C is 100 kPa or less.

13. An optical adhesive sheet comprising the adhesive layer provided in an image display device, The optical adhesive sheet according to any one of claims 1 to 12, wherein the image display device comprises the adhesive layer and a pair of image display device members formed on one side and the other side of the optical adhesive sheet in the thickness direction.

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