Method for producing optical multilayer body, and optical multilayer body

Abstract

This method for producing an optical multilayer body comprises: a step A for preparing a first optical sheet that has a first main surface having a relief structure; a step B for preparing an adhesive layer; and a step C for bonding the adhesive layer to the first main surface of the first optical sheet. The relief structure comprises a plurality of recessed portions and a flat portion that is positioned between adjacent recessed portions. Each one of the plurality of recessed portions has an inclined surface that has an inclination angle θa. The stress Sp is obtained by dividing the 180° peel strength of the adhesive layer with respect to the first main surface of the first optical sheet by the film cross-sectional area, the 180° peel strength being determined by 180° peel test. P1 is the pressure at the time when the adhesive layer is bonded to the first main surface of the first optical sheet in step C. Pf is the pressure that is applied to the flat portion at the time when the adhesive layer is bonded to the first main surface of the first optical sheet in step C. If Dd is the value obtained by multiplying the strain corresponding to Pf in the compressive stress-strain curve of the adhesive layer by the thickness Dt of the adhesive layer in cases where (Sp × sinθa) ≥ Pf, and Dd is the value obtained by multiplying the strain corresponding to (Sp × sinθa) in the compressive stress-strain curve of the adhesive layer by the thickness Dt of the adhesive layer in cases where (Sp × sinθa) < Pf, Dd is 1.3 µm or less.

Description

Method for manufacturing optical laminate and optical laminate

[0001] The present invention relates to a method for producing an optical laminate and an optical laminate.

[0002] Optical sheets (e.g., microlens sheets, prism sheets, brightness enhancement films (e.g., Brightness Enhancement Film: BEF (registered trademark) manufactured by 3M)) are used in various optical devices (e.g., display devices and lighting devices). In this specification, the term "optical sheet" is not limited to the above-mentioned examples but broadly includes sheet-like optical members, further including, for example, a diffuser plate and a light guide plate. An optical sheet is attached to another optical sheet or an optical device, for example, using an adhesive layer. In this specification, the term "optical laminate" refers to a configuration including an optical sheet and an adhesive layer or a configuration including multiple optical sheets. In this specification, the term "adhesive" is used to include a pressure-sensitive adhesive (also called a "pressure-sensitive adhesive").

[0003] The present applicant has disclosed in Patent Document 1 an optical laminate (referred to as an "optical laminate sheet" in Patent Document 1) that can be used in display devices and lighting devices. The optical laminate of Patent Document 1 includes an optical sheet (e.g., a microlens sheet) having a concave-convex structure on its surface, and an adhesive layer provided on the surface having the concave-convex structure. 5% to 90% of the height of the convex portions of the concave-convex structure is filled with the adhesive layer. The adhesive layer is formed from an adhesive composition containing a graft polymer obtained by graft polymerizing a chain containing a cyclic ether group-containing monomer onto a (meth)acrylic polymer, and a photocationic polymerization initiator or a thermosetting catalyst.

[0004] Furthermore, Patent Documents 2 and 3 disclose light distribution structures that utilize total reflection at the interfaces of multiple air cavities, which can be used in display devices and lighting devices. The use of the light distribution structures disclosed in Patent Documents 2 and 3 can improve the degree of freedom and accuracy of light distribution control. The entire disclosures of Patent Documents 2 and 3 are incorporated herein by reference.

[0005] Patent Document 1: JP 2012-007046 A, International Publication No. 2011 / 124765, International Publication No. 2019 / 087118

[0006] When an adhesive layer is applied to the surface of an optical sheet having a concave-convex structure, the degree to which the adhesive layer penetrates into (fills) the recesses of the concave-convex structure affects the function of the optical sheet. Therefore, it is necessary to suppress the degree to which the adhesive layer penetrates into the recesses of the concave-convex structure (the ratio of the volume of the adhesive layer present in the space to the volume of the space defined by the recesses of the concave-convex structure).

[0007] The present inventors have also considered forming a plurality of air cavities (internal spaces) that constitute the light distribution structure (light distribution control structure) described in Patent Documents 2 and 3 by the surface of an optical sheet having a concave-convex structure and the surface of an adhesive layer attached to the surface of the optical sheet having a concave-convex structure. Patent Documents 2 and 3 do not describe that a plurality of air cavities (internal spaces) that constitute the light distribution structure are formed by the surface of the optical sheet having a concave-convex structure and the surface of the adhesive layer.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a method for producing an optical laminate having an adhesive layer that is reduced in the degree to which it penetrates into the recesses of the uneven structure of the optical sheet, and to provide such an optical laminate.

[0009] According to an embodiment of the present invention, the following solutions are provided:

[0010] [Item 1] A first optical sheet having a first main surface with a concave-convex structure and a second main surface opposite to the first main surface, the concave-convex structure including a plurality of recesses and flat portions between adjacent recesses among the plurality of recesses, the method including: Step A of preparing a first optical sheet; Step B of preparing an adhesive layer; and Step C of bonding the adhesive layer to the first main surface of the first optical sheet, wherein each of the plurality of recesses has an inclined surface with an inclination angle θa; a stress obtained by dividing a 180° peel adhesive strength of the adhesive layer to the first main surface of the first optical sheet, as determined by a 180° peel test, by a film cross-sectional area is Sp; a pressure when bonding the adhesive layer to the first main surface of the first optical sheet in step C is Pl; and a pressure applied to the flat portion when bonding the adhesive layer to the first main surface of the first optical sheet in step C is Pf; A method for producing an optical laminate, wherein when Sp×sin θa≧Pf, the value Dd is obtained by multiplying the strain corresponding to Pf in the compressive stress-strain curve of the adhesive layer by the thickness Dt of the adhesive layer, and when Sp×sin θa<Pf, the value Dd is obtained by multiplying the strain corresponding to Sp×sin θa in the compressive stress-strain curve of the adhesive layer by the thickness Dt of the adhesive layer, and Dd is 1.3 μm or less. [Item 2] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 3] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 4] The method for producing an optical laminate, wherein Dd is 1.3 μm or less. [Item 5] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 6] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 7] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 8] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 9] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 10] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 11] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 12] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 13] The method for producing an optical laminate, wherein Dd is 0.5 μm or less. [Item 14] The method for producing an optical laminate, wherein Dt is 3 μm or more and 10 μm or less. [Item 15] The compressive stress (y)-strain (x) curve of the adhesive layer is expressed by the following equation ｂ The manufacturing method according to any one of items 1 to 4, wherein a is 150 or more and b is 2 or more. [Item 6] The compressive stress (y)-strain (x) curve of the adhesive layer is approximated by y=a×x ｂ The manufacturing method according to item 5, wherein the compressive stress (y)-strain (x) curve of the adhesive layer is approximated by y=a×x ｂwhere a is 30 or less and b is 2 or more. [Item 8] The manufacturing method according to any one of items 1 to 7, wherein Sp × sin θa < Pf is satisfied. [Item 9] The manufacturing method according to any one of items 1 to 8, wherein the stress Sp is 0.5 MPa or less. [Item 10] The manufacturing method according to any one of items 1 to 8, wherein the stress Sp is 1.0 MPa or more. [Item 11] The manufacturing method according to any one of items 1 to 10, wherein the adhesive layer is formed by crosslinking an adhesive composition comprising a polyester resin which is a copolymer of a polycarboxylic acid and a polyhydric alcohol, a crosslinking agent, and at least one crosslinking catalyst selected from the group consisting of an organic zirconium compound, an organic iron compound, and an organic aluminum compound, and wherein the adhesive layer has a gel fraction of 40% or more after being held at a temperature of 85°C and a relative humidity of 85% for 300 hours, and a 180° peel adhesive strength to a PMMA film of 100 mN / 20 mm or more. [Item 12] The manufacturing method according to any one of Items 1 to 10, wherein the adhesive layer is the following adhesive layer Aa or adhesive layer Ab: an adhesive layer Aa, which, in a creep test using a rotational rheometer, has a creep deformation rate of 10% or less when a stress of 10,000 Pa is applied for 1 second at 50°C and a creep deformation rate of 16% or less when a stress of 10,000 Pa is applied for 30 minutes at 50°C, and has a 180° peel adhesive strength to a PMMA film of 10 mN / 20 mm or more; an adhesive layer Ab, which is formed by curing the curable resin of an adhesive composition containing a polymer and a curable resin, and has an initial tensile modulus at 23°C before curing the curable resin of the adhesive composition of 0.35 MPa or more and 8.00 MPa or less, and has an initial tensile modulus at 23°C after curing the curable resin of the adhesive composition of 1.00 MPa or more. [Item 13] The manufacturing method according to any one of Items 1 to 12, wherein the inclined surface directs a portion of the light propagating within the adhesive layer toward the second main surface of the first optical sheet by total internal reflection.[Item 14] The manufacturing method according to any one of Items 1 to 13, wherein each of the plurality of recesses has another inclined surface opposite to the inclined surface, and an inclination angle θa of the inclined surface is smaller than an inclination angle θb of the other inclined surface. Item 15. The manufacturing method according to any one of Items 1 to 14, wherein Step B includes: Step Ba of applying an adhesive composition solution containing a (meth)acrylic polymer and / or a polyester polymer, a crosslinking agent, and a solvent onto a release-treated main surface of a substrate having the adhesive composition solution layer, to form an adhesive composition solution layer; Step Bb of removing the solvent from the adhesive composition solution layer to form an adhesive composition layer; Step Bc of providing another substrate having a release-treated main surface on a main surface of the adhesive composition layer opposite the substrate, such that the release-treated main surface is in contact with the adhesive composition layer; and Step Bd of crosslinking the (meth)acrylic polymer and / or polyester polymer in the adhesive composition layer with the crosslinking agent to form the adhesive layer; and Step C includes Step Ca of bonding the first main surface of the first optical sheet to one main surface of the substrate or the other substrate for the adhesive layer. [Item 16] The manufacturing method according to item 15, wherein the release-treated main surface of the one of the substrate or the other substrate has an arithmetic mean roughness Ra of less than 0.05 μm. [Item 17] The manufacturing method according to item 16, wherein the release-treated main surface of the one of the substrate or the other substrate has a maximum height Rz of less than 0.5 μm. [Item 18] The manufacturing method according to any one of items 15 to 17, wherein step Ca is performed by a roll-to-roll method. [Item 19] The manufacturing method according to any one of items 1 to 18, wherein, when Rr is a ratio of an area of ​​the plurality of recesses to an area of ​​the first optical sheet when viewed in a planar view from a normal direction to the first main surface, a pressure Pf applied to the flat portion in step C is obtained by dividing the pressure Pl in step C by (1-Rr).[Item 20] A first optical sheet having a first main surface with a concave-convex structure and a second main surface opposite the first main surface, wherein the concave-convex structure includes a plurality of recesses and flat portions between adjacent recesses among the plurality of recesses; and an adhesive layer disposed on the first main surface side of the first optical sheet and in contact with the flat portions, wherein a surface of the adhesive layer and the first main surface of the first optical sheet define an internal space within each of the plurality of recesses, and each of the plurality of recesses has an inclined surface with an inclination angle θa, the adhesive layer is attached to the first main surface of the first optical sheet with a pressure Pl, Pf is the pressure applied to the flat portions when attaching the adhesive layer to the first main surface of the first optical sheet, and Sp is the stress obtained by dividing the 180° peel adhesive strength of the adhesive layer to the first main surface of the first optical sheet by a cross-sectional area of ​​the film, as determined in a 180° peel test, 21. An optical laminate, wherein, when Sp×sin θa≧Pf, Dd is the value obtained by multiplying the strain corresponding to Pf in the compressive stress-strain curve of the adhesive layer by the thickness Dt of the adhesive layer, and when Sp×sin θa<Pf, Dd is the value obtained by multiplying the strain corresponding to Sp×sin θa in the compressive stress-strain curve of the adhesive layer by the thickness Dt of the adhesive layer, Dd is 1.3 μm or less. [Item 21] The adhesive layer is formed by crosslinking an adhesive composition containing a polyester resin which is a copolymer of a polycarboxylic acid and a polyhydric alcohol, a crosslinking agent, and at least one crosslinking catalyst selected from the group consisting of an organic zirconium compound, an organic iron compound, and an organic aluminum compound, and has a gel fraction of 40% or more after being held at a temperature of 85°C and a relative humidity of 85% for 300 hours, and has a 180° peel adhesive strength to a PMMA film of 100 mN / 20 mm or more.[Item 22] The optical laminate according to Item 20, wherein the adhesive layer is an adhesive layer Aa or an adhesive layer Ab as follows: an adhesive layer Aa, which, in a creep test using a rotational rheometer, has a creep deformation rate of 10% or less when a stress of 10,000 Pa is applied for 1 second at 50°C and a creep deformation rate of 16% or less when a stress of 10,000 Pa is applied for 30 minutes at 50°C, and has a 180° peel adhesive strength to a PMMA film of 10 mN / 20 mm or more; an adhesive layer Ab, which is formed by curing the curable resin of an adhesive composition containing a polymer and a curable resin, and has an initial tensile modulus at 23°C before curing the curable resin of the adhesive composition of 0.35 MPa or more and 8.00 MPa or less, and has an initial tensile modulus at 23°C after curing the curable resin of the adhesive composition of 1.00 MPa or more.

[0011] According to an embodiment of the present invention, a method for manufacturing an optical laminate having an adhesive layer with reduced penetration into recesses of the relief structure of an optical sheet, and such an optical laminate are provided.

[0012] 1 is a schematic cross-sectional view of an optical laminate 100A according to an embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of an optical laminate 101A according to another embodiment of the present invention; FIG. 3 is a schematic cross-sectional view of the optical laminate 100A; FIG. 4 is a schematic perspective view of a first optical sheet 10a included in the optical laminate 100A; FIG. 5 is a schematic cross-sectional view of an illumination device 200A including the optical laminate 100A; FIG. 6 is a schematic cross-sectional view of an illumination device 200B including the optical laminate 100A; FIG. 7 is a diagram schematically illustrating a process for manufacturing the optical laminate 100A by a roll-to-roll method; FIG. 8 is a diagram schematically illustrating a process for manufacturing the optical laminate 100A by a roll-to-roll method; FIG. 9 is a schematic diagram for explaining a problem when manufacturing the optical laminate of a reference example by a roll-to-roll method; FIG. 10 is a schematic diagram for explaining a problem when manufacturing the optical laminate of a reference example by a roll-to-roll method; FIG. 11 is a diagram schematically illustrating an example of a process for manufacturing the optical laminate 100A. 1 is a diagram schematically illustrating an example of a process for producing an optical laminate 100A. FIG. 1 is a schematic plan view of a textured film 70 included in an optical laminate according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the textured film 70. FIG. 3 is a graph showing evaluation results of the area ratio (%) of bubbles and the height (μm) of the adhesive layer present in the recesses in the optical laminates of the examples. FIG. 4 is a schematic diagram for explaining a method for evaluating changes in the degree of penetration of the adhesive layer into the recesses using an optical laminate. FIG. 5 is a schematic cross-sectional view for explaining a method for evaluating changes in the degree of penetration of the adhesive layer into the recesses using an optical laminate. FIG. 6 is an optical image of a sample 1000A having the optical laminate 100S of Example A, where the top row is an optical image of the sample 1000A before force is applied, the middle row is an optical image of the sample 1000A when force is being applied, and the bottom row is an optical image of the sample 1000A after the force has been removed. 1 is a diagram showing optical images of a sample having the optical laminate of Example B, where the upper row is an optical image of the sample before force is applied, the middle row is an optical image of the sample when force is being applied, and the lower row is an optical image of the sample after the force has been removed. FIG. 1 is a schematic plan view of a textured film 52 possessed by an optical laminate according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a textured film 52 possessed by an optical laminate according to an embodiment of the present invention. FIG. 3 is a schematic plan view of a textured film 82 possessed by an optical laminate according to an embodiment of the present invention.1 is a schematic cross-sectional view of a recess 84 of a textured film 82. FIG. 2 is a schematic plan view of a recess 84 of a textured film 82. FIG. 3 is a schematic view for explaining a method for calculating a calculated embedded amount Dd of an adhesive layer. FIG. 4 is a schematic view for explaining a method for calculating a calculated embedded amount Dd of an adhesive layer. FIG. 5 is a schematic view for explaining a method for calculating a calculated embedded amount Dd of an adhesive layer. FIG. 6 is a graph showing the correlation between the measured value of the height (μm) of an adhesive layer present in a recess and the calculated embedded amount Dd (μm). FIG. 7 is a schematic perspective view for explaining a method for measuring a compressive stress-strain curve of an adhesive layer. FIG. 8 is a schematic cross-sectional view for explaining a method for measuring a 180° peel adhesive strength of an adhesive layer to an optical sheet. FIG. 9 is a schematic top view for explaining a method for measuring a 180° peel adhesive strength of an adhesive layer to an optical sheet. FIG. 10 is a schematic cross-sectional view for explaining a method for measuring a 180° peel adhesive strength of an adhesive layer to an optical sheet.

[0013] An optical stack and an optical device having the optical stack according to an embodiment of the present invention will be described below, but the embodiment of the present invention is not limited to the following examples.

[0014] An optical laminate according to an embodiment of the present invention includes an optical sheet having a first main surface with a concave-convex structure and a second main surface opposite the first main surface, and an adhesive layer disposed on the first main surface side of the optical sheet. First, with reference to Figures 1A, 1B, 2, 3, 4A, and 4B, an example will be described in which the adhesive layer attached to the surface (first main surface) of the optical sheet having the concave-convex structure does not penetrate into the concaves of the concave-convex structure.

[0015] Fig. 1A shows a schematic cross-sectional view of an optical laminate 100A according to an embodiment of the present invention. Fig. 1B shows a schematic cross-sectional view of an optical laminate 101A according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing an enlarged portion of the optical laminate 100A. Fig. 3 is a schematic perspective view of an optical sheet 10a included in the optical laminate 100A. Fig. 4A is a schematic cross-sectional view of an illumination device 200A including the optical laminate 100A.

[0016] 1A , the optical laminate 100A includes a first optical sheet 10a having a first major surface 12s with a concave-convex structure and a second major surface 18s opposite the first major surface 12s, and an adhesive layer 20a disposed on the first major surface 12s side of the first optical sheet 10a. The concave-convex structure of the first major surface 12s includes a plurality of recesses 14 and flat portions 10s between adjacent recesses 14 among the plurality of recesses 14. The adhesive layer 20a is in contact with the flat portions 10s. The surface of the adhesive layer 20a and the first major surface 12s of the first optical sheet 10a define internal spaces 14a within each of the plurality of recesses 14.

[0017] 1B , the optical laminate 101A includes the optical laminate 100A and a second optical sheet 30 disposed on the side of the adhesive layer 20a opposite to the first optical sheet 10a side. Unless otherwise specified, the description of the optical laminate 100A also applies to the optical laminate 101A, and therefore, the description may be omitted to avoid redundancy.

[0018] The second optical sheet 30 of the optical laminate 101A has a main surface 38s on the adhesive layer 20a side and a main surface 32s opposite the main surface 38s. The main surface 38s is a flat surface. At least one other optical member (or optical sheet) may be disposed on the side of the second optical sheet 30 of the optical laminate 101A opposite the adhesive layer 20a (i.e., on the main surface 32s). The other optical member (optical sheet) may include, for example, a diffuser plate, a light guide plate, etc., and is adhered to the main surface 32s of the optical sheet 30 via an adhesive layer.

[0019] In the examples shown in FIGS. 1A and 2 , the adhesive layer 20a does not penetrate into the recess 14. That is, the adhesive layer 20a does not exist in the space defined by the recess 14. The space defined by the recess 14 refers to the space defined by the recess 14 and the sheet surface (a plane parallel to the XY plane) including the flat portion 10s adjacent to the recess 14. Therefore, in this example, the internal space 14a defined by the surface 28s of the adhesive layer 20a facing the first optical sheet 10a and the first main surface 12s of the first optical sheet 10a coincides with the space defined by the recess 14. The internal space 14a is sometimes referred to as an air cavity or an optical cavity. The internal space 14a is typically a void filled with air. However, the internal space 14a may be filled with a material having a lower refractive index than the first optical sheet 10a and the adhesive layer 20a instead of air. In a plan view (XY plane) of the optical sheet seen from the normal direction to the main surface, the multiple internal spaces may be internal spaces (e.g., triangular prism-shaped grooves extending in the X direction) that are continuous in the X direction and discretely provided in the Y direction, as in the example of FIG. 3 , or may be discrete islands that are provided in both the X and Y directions, as in the example of FIG. 9A . Note that, as shown in FIGS. 4A and 4B described below, in an illumination device including the optical laminate 100A, the light guide direction of the light guide layer 80 is the −Y direction. Note that, although light propagates in various directions within the light guide layer 80, the −Y direction is referred to as the light guide direction, and light having a component in the −Y direction (that is not zero) is said to propagate in the −Y direction.

[0020] The optical laminate 100A functions as the light distribution structure described in Patent Documents 2 and 3. The optical laminate 100A has multiple internal spaces 14a that form interfaces that direct light in the Z direction (downward in the figure) by total internal reflection. The internal spaces 14a are defined by surfaces 16s and 17s, which are part of the first major surface 12s of the first optical sheet 10a, and a surface 28s of the adhesive layer 20a on the first optical sheet 10a side. Here, the cross-sectional shape of the internal spaces 14a (the shape of a cross section perpendicular to the X direction and parallel to the YZ plane) is triangular. The interfaces formed by the inclined surfaces 16s function as interfaces that direct light in the Z direction (downward in the figure) by total internal reflection. Each of the multiple recesses 14, i.e., each of the multiple internal spaces 14a, has an inclined surface (first inclined surface) 16s that directs a portion of the light propagating within the optical laminate 100A toward the second main surface 18s of the first optical sheet 10a (Z direction in the figure) by total internal reflection, and an inclined surface (second inclined surface) 17s opposite the inclined surface 16s. The inclination angle θa of the inclined surface 16s is, for example, 10° or more and 70° or less. The lower limit is preferably 30° or more, more preferably 45° or more. If the inclination angle θa is less than 10°, the controllability of the light distribution may decrease and the light extraction efficiency may also decrease. On the other hand, if the inclination angle θa exceeds 70°, for example, processing of a textured film may become difficult. Furthermore, the inclination angle θb of the inclined surface 17s is, for example, 50° or more and 100° or less. The lower limit is preferably 70° or more. If the inclination angle θb is less than 50°, stray light may be generated in an unintended direction. On the other hand, if the inclination angle θb exceeds 100°, it may be difficult to process, for example, a textured film. The inclination angle θa of the inclined surface 16s and the inclination angle θb of the inclined surface 17s are angles relative to a direction parallel to the Y direction in the cross section of the recess 14 (a cross section perpendicular to the X direction and parallel to the YZ plane). In this example, the inclination angle θa of the inclined surface 16s is smaller than the inclination angle θb of the inclined surface 17s. In a lighting device having the optical laminate 100A (see FIGS. 4A and 4B), the inclined surface 16s is positioned closer to the light source 60 than the inclined surface 17s. The cross-sectional shape (a cross section perpendicular to the X direction and parallel to the YZ plane) of the internal space 14a is determined by the inclination angle θa of the inclined surface 16s and the inclination angle θb of the inclined surface 17s, the width Wy, and the depth C.The shape of the internal space 14 a (recess 14) is not limited to the illustrated one and can be modified in various ways. By adjusting the shape, size, arrangement density, etc. of the internal space 14 a (recess 14), it is possible to adjust the distribution (light distribution) of light rays emitted from the optical laminate 100A (see, for example, Patent Documents 2 and 3).

[0021] The optical laminate functioning as a light distribution control structure can constitute a light guide layer and / or a light direction conversion layer having multiple internal spaces. For example, as shown in FIG. 4A , the optical laminate 100A is used in a lighting device 200A. The lighting device 200A includes an optical laminate 102A and a light source 60. The optical laminate 102A includes the optical laminate 100A and a light guide layer 80 provided on the side of the adhesive layer 20a of the optical laminate 100A opposite the first optical sheet 10a side. The light guide layer 80 is bonded, for example, to a surface 22s of the adhesive layer 20a opposite the first optical sheet 10a side. The light guide layer 80 has a first major surface 80a, a second major surface 80b opposite the first major surface 80a, and a light receiving unit 80c that receives light emitted from the light source 60. The light source 60 is, for example, an LED device, and a plurality of LED devices may be arranged in an array. A portion of the light guided into the light guide layer 80 is totally internally reflected (TIR) ​​at the interface 16s and the interface 14s formed by the internal space 14a, as shown by the arrows in Fig. 4A. The light totally internally reflected at the interface 14s (the surface 28s of the adhesive layer 20a on the first optical sheet side) propagates through the light guide layer 80 and the adhesive layer 20a, and the light totally internally reflected at the inclined surface 16s is emitted to the outside of the optical laminate 102A from the second main surface 18s side of the first optical sheet 10a.

[0022] Here, it is preferable that the refractive indices of the light guide layer 80, the adhesive layer 20a, and the first optical sheet 10a are approximately equal to one another. The difference (absolute value) between the refractive indices of the light guide layer 80 and the adhesive layer 20a, and the difference (absolute value) between the refractive indices of the adhesive layer 20a and the first optical sheet 10a are each independently preferably 0.20 or less, more preferably 0.15 or less, and even more preferably 0.10 or less.

[0023] The thickness of the adhesive layer 20a is, for example, 2.0 μm or more and 15.0 μm or less. The lower limit is preferably 4.0 μm or more. The upper limit is preferably 11.0 μm or less, and more preferably 9.0 μm or less. Unless otherwise specified, the thickness of the adhesive layer 20a refers to the thickness on the flat portion 10s of the first main surface 12s of the first optical sheet 10a.

[0024] The haze value of the optical laminate 100A is, for example, 5.0% or less. The haze value can be measured using, for example, a haze meter (device name "HZ-1", manufactured by Suga Test Instruments Co., Ltd.) under D65 light.

[0025] 4B , the light guide layer 80 may be provided on the first optical sheet 10a side of the optical laminate 100A (closer to the first optical sheet 10a than the adhesive layer 20a). The light guide layer 80 and the first optical sheet 10a may be attached via an adhesive layer. In the lighting device 200B as well, the light totally internally reflected at the interface 14s (the surface 28s of the adhesive layer 20b facing the first optical sheet) propagates within the adhesive layer 20a, and the light totally internally reflected at the inclined surface 16s is emitted to the outside of the optical laminate 102B from the second main surface 18s of the first optical sheet 10a.

[0026] The lighting device according to the embodiment of the present invention is not limited to the above-described example and may be modified in various ways. For example, a substrate layer may be provided on the lighting device 200A on the side opposite the light-guiding layer 80 of the optical stack 100A. An anti-reflection layer may be provided instead of the substrate layer, or a hard coat layer (e.g., having a pencil hardness of H or higher) may be provided instead of the substrate layer. An anti-reflection layer and / or a hard coat layer may be provided on the substrate layer. Furthermore, an anti-reflection layer and / or a hard coat layer may be provided on the side opposite the light-emitting surface of the light-guiding layer 80 (upper side in the figure). The anti-reflection layer and the hard coat layer may be formed using known materials and by known methods. A low refractive index layer may be provided between the optical stack 102A and the substrate layer (or the anti-reflection layer and / or the hard coat layer).

[0027] In the example of the lighting device 200B, a substrate layer may be provided on the side of the optical laminate 100A opposite to the light guide layer 80. Instead of the substrate layer, an antireflection layer and / or a hard coat layer (e.g., having a pencil hardness of H or higher) may be provided, or the antireflection layer and / or the hard coat layer may be provided on the substrate layer. Furthermore, an antireflection layer and / or a hard coat layer may be provided on the light exit surface side (lower side in the figure) of the light guide layer 80. A low refractive index layer may be provided between the optical laminate 102B and the substrate layer (or the antireflection layer and / or the hard coat layer).

[0028] As shown in FIG. 3 , when the first optical sheet 10a is viewed in a plan view from the normal direction of the first main surface 12s, each of the multiple recesses 14 extends in the X direction and is continuous in the X direction. The multiple recesses 14 are arranged discretely in the Y direction, with flat portions 10s provided between the recesses 14. In the Y direction, the recesses 14 are preferably arranged periodically in the Y direction, with a pitch Py of, for example, 6 μm to 120 μm. The width Wy of each recess 14 is, for example, 3 μm to 20 μm, and the width Dy of each flat portion 10s is, for example, 3 μm to 100 μm. The ratio Wy / Dy of the width Wy of each recess 14 to the width Dy of each flat portion 10s is, for example, 0.3 to 7. The depth C (depth in the Z direction) of each recess 14 is, for example, 1 μm to 100 μm. The depth C of each recess 14 is preferably 20 μm or less, and more preferably 12 μm or less. The depth C of the recess 14 is preferably 4 μm or more, more preferably 6 μm or more, and even more preferably 8 μm or more.

[0029] Regarding the density of the plurality of recesses 14, when the first optical sheet 10a is viewed in a plan view from the normal direction to the first main surface 12s, the ratio of the area of ​​the plurality of recesses 14 to the area of ​​the first optical sheet 10a (occupancy rate) is preferably 0.3% or more from the viewpoint of obtaining good brightness. The occupation rate of the plurality of recesses 14 is appropriately selected depending on the application. For example, in applications requiring transparency, it is preferably 0.3% or more and 10% or less, and more preferably 0.5% or more and 4% or less. In applications requiring higher brightness, it is preferably 30% or more and 80% or less. The occupation rate of the plurality of recesses 14 may be uniform, or may increase with increasing distance from a light source (e.g., light source 60 in FIG. 4A or 4B ) so that brightness does not decrease even with increasing distance.

[0030] Instead of the first optical sheet 10a, for example, a concave-convex shaped film 70 (optical sheet) shown in FIGS. 9A and 9B may be used. The concave-convex shaped film 70 has a main surface with a concave-convex structure, and the concave-convex structure has a plurality of recesses 74 and flat portions 72s between adjacent recesses 74. When the concave-convex shaped film 70 is viewed in a plan view from the normal direction of the main surface (see, for example, FIG. 9A), the plurality of recesses 74 are arranged in a discrete island-like manner in both the X and Y directions. In the shaped film 70, the size of the recesses 74 (length L, width W: see FIGS. 9A and 9B) is, for example, preferably 10 μm or more and 500 μm or less, and preferably 1 μm or more and 100 μm or less. In addition, from the viewpoint of light extraction efficiency, the depth H is preferably 1 μm or more and 100 μm or less. The depth H of the recesses 74 is preferably 20 μm or less, more preferably 12 μm or less. The depth H of the recesses 74 is preferably 4 μm or more, more preferably 6 μm or more, and even more preferably 8 μm or more. When the recesses 74 are distributed discretely and uniformly, they are preferably arranged periodically, for example, as shown in FIG. 9A . The pitch Px is preferably 10 μm or more and 500 μm or less, for example, and the pitch Py is preferably 10 μm or more and 500 μm or less. Note that the example of FIG. 9A is not limited thereto, and when used in a lighting device, the recesses may be arranged discretely in the light guide direction of the light guide layer and in a direction intersecting the light guide direction of the light guide layer.

[0031] The density of the plurality of recesses 74 is preferably 0.3% or more in terms of obtaining good brightness when the unevenly shaped film 70 is viewed in a plan view from the normal direction of the main surface (FIG. 9A). The ratio of the area of ​​the plurality of recesses 74 to the area of ​​the unevenly shaped film 70 (occupancy rate) is selected appropriately depending on the application. For example, in applications requiring transparency, it is preferably 30% or less to obtain good visible light transmittance and haze value, and it is preferably 1% or more to obtain good brightness. The upper limit is more preferably 25% or less, and to obtain high visible light transmittance, it is preferably 10% or less, and more preferably 5% or less. For example, it is preferably 0.3% or more and 10% or less, and more preferably 0.5% or more and 4% or less. For applications requiring higher brightness, it is preferably 30% or more and 80% or less. The area ratio of the recesses 74 may be uniform, or may increase with increasing distance from the light source (e.g., light source 60 in FIG. 4A or 4B) so that brightness does not decrease even with increasing distance.

[0032] Although an example in which the cross-sectional shape of the recess 14 is triangular has been shown, the cross-sectional shape of the recess 14 is not limited to this and may be, for example, a quadrangle (e.g., a trapezoid) as long as it has a surface that can form an interface that directs light in the Z direction by total internal reflection. Furthermore, the cross-sectional shape is not limited to a polygon and may be a shape that includes at least a curved line. Examples of a shape that includes at least a curved line include a part of the circumference of a circle or ellipse, or a shape that includes a combination of multiple curves with different curvatures.

[0033] Instead of the first optical sheet 10a, for example, a textured film 82 (optical sheet) shown in FIG. 15A may be used. FIG. 15A also shows a light source 60. The textured film 82 has a main surface with a textured structure, and the textured structure has a plurality of recesses 84 and flat portions 82s between adjacent recesses 84. Each of the plurality of recesses 84 has a first inclined surface 86s that directs a portion of the light propagating within the optical laminate in the Z direction by total internal reflection, and a second inclined surface 87s opposite the first inclined surface 86s. As shown in FIG. 15A, when viewed in a plan view from the normal direction of the main surface having the textured structure of the textured film 82, the first inclined surface 86s of the recess 84 forms a curved surface that is convex toward the light source 60. When a plurality of LED devices arranged in the X direction are used as the light source 60, the light emitted from each LED device spreads in the Y direction. Therefore, if the first inclined surface 86s has a convex curve toward the light source LS, the first inclined surface 86s acts uniformly on the light. Note that, if a coupling optical system is provided between the light source 60 and the light receiving section 80c of the light guide layer 80 to allow highly parallel light (light with little spread in the Y direction) to enter, the first inclined surface 86s may be parallel to the X direction. The preferred ranges of the size (length L, width W: see FIGS. 15B and 15C ), depth H (see FIG. 15C ), and pitches Px and Py of the recesses 84 may be the same as those of the recesses 74 of the texture-imprinted film 70, for example.

[0034] The optical laminate 100A can be manufactured by attaching the adhesive layer 20a to the surface 12s having the concave-convex structure of the first optical sheet 10a, for example, by using a roll-to-roll method. From the viewpoint of mass productivity, it is preferable to manufacture the optical laminate 100A by the roll-to-roll method as shown in FIG.

[0035] As shown in FIG. 5 , the first optical sheet 10 a and the adhesive layer 20 a are bonded together by rolls Ra and Rb rotating in the direction of the arrows. For example, one of the rolls Ra and Rb is a drive roll, and the other is a driven roll. At this time, the pressure (nip pressure, bonding pressure, lamination pressure) applied to the first optical sheet 10 a and the adhesive layer 20 a between the rolls Ra and Rb may vary depending on the position in the transverse direction (TD) of the optical laminate 100A (the direction parallel to the axes of the rolls Ra and Rb). Typically, as shown in FIG. 6 , the pressure applied to the first optical sheet 10 a and the adhesive layer 20 a is greater at both end portions Ae in the TD direction than at the center portion Ad in the TD direction. In FIG. 6 , the size of the outline arrows schematically indicates the magnitude of the pressure applied to the first optical sheet 10 a and the adhesive layer 20 a between the rolls Ra and Rb.

[0036] According to the studies of the present inventors, when the optical laminate of the reference example is manufactured by a roll-to-roll process using the adhesive layer 90 of the reference example and the first optical sheet 10a, the following problems may occur. Here, an example will be described in which an optical laminate is manufactured by a roll-to-roll process using the adhesive layer 90 of the reference example instead of the adhesive layer 20a of the optical laminate 100A according to an embodiment of the present invention.

[0037] 7A , if the pressure is adjusted so that an appropriate pressure is applied to the optical sheet 10a and the adhesive layer 90 at the central portion Ad in the TD direction, i.e., so that the adhesive layer 90 has good adhesion to the uneven surface 12s of the optical sheet 10a while preventing the adhesive layer 90 from penetrating into the recesses 14, a greater pressure is applied to the first optical sheet 10a and the adhesive layer 90 at both end portions Ae in the TD direction, which may cause the adhesive layer 90 to excessively penetrate into the recesses 14 at both end portions Ae. On the other hand, if the pressure is adjusted so that an appropriate pressure is applied to the optical sheet 10a and the adhesive layer 90 at both end portions Ae in the TD direction, as shown in FIG. 7B , the pressure applied to the first optical sheet 10a and the adhesive layer 90 at the central portion Ad is smaller, which may cause excessive air bubbles BA to form at the interface between the flat portion 10s of the first optical sheet 10a and the adhesive layer 90, resulting in insufficient adhesion to the uneven surface 12s of the first optical sheet 10a. As described above, when a conventional adhesive layer is used, it may be difficult to simultaneously prevent the adhesive layer from penetrating into the recesses 14 of the concave-convex structure and prevent air bubbles from forming at the interface between the adhesive layer and the flat portions 10s of the concave-convex structure. The length in the TD direction of an optical laminate produced by the roll-to-roll method is, for example, about several meters. The longer the length in the TD direction of the optical laminate, the more likely this problem is to occur.

[0038] The present inventors have discovered that the use of a specific adhesive layer 20a, as shown in FIG. 8A , can solve the problems described with reference to FIGS. 7A and 7B . The arrow on the left in FIG. 8A indicates a timeline. A first optical sheet 10a and an adhesive layer 20a are prepared (top row of FIG. 8A ). When the adhesive layer 20a is bonded to the surface of the first optical sheet 10a having a concave-convex structure, sufficient pressure is applied to prevent excessive air bubbles from forming at the interface between the flat portion 10s of the concave-convex structure and the adhesive layer 20a. During lamination, the adhesive layer 20a may temporarily penetrate excessively into the recesses 14 (middle row of FIG. 8A ). This is because, once the pressure applied during lamination is removed, the degree to which the adhesive layer 20a penetrates (embedding) into the recesses 14 decreases (bottom row of FIG. 8A ). An example of such an adhesive layer 20a is shown in the experimental example described below. In the obtained optical laminate 100A, penetration of the adhesive layer 20a into the recesses 14 is suppressed, and air bubbles present at the interface between the flat portions 10s of the concave-convex structure and the adhesive layer 20a are suppressed. In an optical laminate according to an embodiment of the present invention, when viewed in a plan view from the normal direction of the first main surface of the first optical sheet, the area ratio of air bubbles present at the interface between the flat portions 10s and the adhesive layer 20a to the area of ​​the first optical sheet is 3% or less, and the height of the adhesive layer 20a present in multiple recesses 14 is 2 μm or less. The height of the adhesive layer 20a present in the recesses 14 is the height of the adhesive layer 20b in the Z direction at the cross section of the recess 14 (a cross section perpendicular to the X direction and parallel to the YZ plane in FIG. 1A ), and is determined using the flat portions 10s as a reference. The height of the adhesive layer 20a present in the recesses 14 can be determined by measuring the maximum height of the adhesive layer 20a present in the recess 14 from a cross-sectional SEM image of an arbitrarily selected recess 14, as performed, for example, in the examples described below. The area ratio of bubbles can be measured, for example, by the method described in the Examples below. The area ratio of bubbles is preferably 2.5% or less, more preferably 1.5% or less, and even more preferably 0.1% or less. The height of the adhesive layer present in the multiple recesses is preferably 1 μm or less, more preferably 0.6 μm or less. Note that the optical laminate according to the embodiment of the present invention is not limited to those produced by the roll-to-roll method.Even in optical laminates produced by methods other than the roll-to-roll method, the intrusion of the adhesive layer into the recesses is suppressed, and air bubbles present at the interface between the flat portion and the adhesive layer are suppressed.

[0039] The likelihood of air bubbles forming at the interface between the flat portion of the concave-convex structure and the adhesive layer is also affected by the surface roughness of the adhesive layer, so the area ratio of air bubbles can also vary depending on the surface roughness of the adhesive layer. If the surface roughness of the adhesive layer (the surface on the first optical sheet side) is high, air bubbles are more likely to form.

[0040] One method for reducing the surface roughness of the adhesive layer surface (the surface on the first optical sheet side) is as follows. The adhesive layer can be formed, for example, by the following method. First, an adhesive composition solution containing a (meth)acrylic polymer and / or a polyester polymer, a crosslinking agent, and a solvent is applied to a release-treated main surface of a substrate (first separator) having a release-treated main surface to form an adhesive composition solution layer. Next, the solvent is removed from the adhesive composition solution layer to form an adhesive composition layer. Subsequently, another substrate (second separator) having a release-treated main surface is provided on the main surface of the adhesive composition layer opposite the first separator side, so that the release-treated main surface is in contact with the adhesive composition layer. Next, the (meth)acrylic polymer and / or polyester polymer in the adhesive composition layer is crosslinked with a crosslinking agent to obtain an adhesive layer. That is, a laminate having a laminate structure of substrate (first separator) / adhesive layer / another substrate (second separator) is obtained. A laminate including a substrate having a release-treated main surface and an adhesive layer is sometimes referred to as an adhesive sheet. An optical laminate according to an embodiment of the present invention can be obtained by bonding either the main surface of the adhesive layer on the first separator side or the main surface of the adhesive layer on the second separator side to the surface of a first optical sheet (a textured film) having a textured structure. For example, when bonding the main surface of the adhesive layer on the second separator side to the surface of a first optical sheet (a textured film) having a textured structure, the arithmetic mean roughness Ra of the release-treated main surface (the surface on the adhesive layer side) of the second separator is preferably less than 0.05 μm, more preferably less than 0.03 μm. The lower limit of the arithmetic mean roughness Ra is not particularly limited, but is, for example, 0.001 μm. Furthermore, the maximum height Rz of the release-treated main surface (the surface on the adhesive layer side) of the second separator is, for example, less than 0.5 μm, preferably less than 0.3 μm. The lower limit of the maximum height Rz is not particularly limited, but is, for example, 0.005 μm.

[0041] When producing an optical laminate using a roll-to-roll process, the y direction or the -y direction of the first optical sheet 10a can be set as the MD (machine direction), for example. For example, in the example shown in FIG. 1, the inclined surface 16s having the smaller inclination angle θa of the recess 14 may be positioned closer to the nip between the rolls Ra and Rb than the inclined surface 17s having the larger inclination angle θb. However, the extent to which the adhesive layer 20a penetrates into the recess 14 does not change significantly depending on the lamination direction.

[0042] [Evaluation of the Amount of Embedding of the Adhesive Layer into the Recesses] The present inventors have discovered that the amount of embedding of the adhesive layer into the recesses (the extent to which the adhesive layer penetrates into the recesses) can be evaluated using the value of the "calculated embedding amount Dd" calculated by the following method: By using the calculated embedding amount Dd, it is possible to evaluate the degree to which the adhesive layer embeds into the recesses without actually bonding the adhesive layer to an optical sheet having recesses on its surface.

[0043] As described with reference to FIG. 8A , the method for manufacturing the optical laminate 100A includes the steps of preparing a first optical sheet 10a (sometimes referred to as “step A”), preparing an adhesive layer 20a (sometimes referred to as “step B”), and bonding the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a (sometimes referred to as “step C”). In step C, the pressure (lamination pressure) applied when bonding the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a is designated Pl. When pressure Pl is applied, the amount of embedding of the adhesive layer 20a into the recesses 14 (here, the maximum height of the adhesive layer within the recesses 14) is maximized (middle row of FIG. 8A ). After that, when pressure Pl is removed, the amount of embedding of the adhesive layer 20a into the recesses 14 decreases (lower row of FIG. 8A ). The amount of embedding of the adhesive layer 20a into the recesses 14 when pressure Pl is applied is designated dmax. Although the bottom part of FIG. 8A shows a state in which the adhesive layer 20a is not embedded in the recess 14 at all, this is not limitative and the amount of embedding may be smaller than that shown in the middle part of FIG. 8A.

[0044] 8B is a diagram schematically illustrating another example of a process for manufacturing the optical laminate 100A. Depending on the type of adhesive layer 20a, as shown in the lower part of FIG. 8B, even when the pressure P1 is removed, the amount of embedding of the adhesive layer 20a into the recess 14 may not decrease (or the degree of decrease may be small). In the example of FIG. 8B, for example, the compressive elastic modulus of the adhesive layer 20a is smaller than in the example of FIG. 8A.

[0045] As shown in Figure 16A, in the optical laminate 100A obtained in this manner (i.e., after a certain time has passed since the pressure Pl was removed), the amount of embedding of the adhesive layer 20a into the recess 14 is thought to be determined by the relationship between the restoring force F1 due to the compressive elasticity of the adhesive layer 20a at the embedding amount dmax and the stress F2 calculated from the peel adhesive force of the adhesive layer 20a to the first optical sheet 10a.

[0046] In the above-mentioned step C (step of bonding the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a), the pressure applied to the flat portions 10s of the first main surface 12s of the first optical sheet 10a when bonding the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a (i.e., when pressure Pl is being applied) is defined as Pf. The pressure Pf applied to the flat portions 10s can be obtained by converting the laminating pressure Pl using the following formula, assuming that pressure is applied only to the flat portions 10s and not to the recessed portions 14 of the first main surface 12s of the first optical sheet 10a: Pf=Pl / (1-Rr), where Pf is the pressure applied to the flat portions 10s, Pl is the laminating pressure, and Rr is the area occupied by the recessed portions 14. The area ratio Rr of the recesses 14 is the ratio of the area of ​​the recesses 14 to the area of ​​the first optical sheet 10a when viewed in a plane from the normal direction to the first main surface 12s. The area of ​​the recesses 14 when viewed in a plane from the normal direction to the first main surface 12s can be obtained by subtracting the area of ​​the flat portions 10s from the area of ​​the first optical sheet 10a when viewed in a plane from the normal direction to the first main surface 12s.

[0047] The restoring force F1 due to compressive elasticity is evaluated using the stress Sm corresponding to the ratio (dmax / Dt) of the embedding amount dmax to the thickness Dt of the adhesive layer 20a in the compressive stress-strain curve of the adhesive layer 20a. The thickness Dt of the adhesive layer 20a is the thickness of the adhesive layer 20a on the flat portion 10s of the first major surface 12s of the first optical sheet 10a, and is the thickness of the adhesive layer 20a before being attached to the first major surface 12s of the first optical sheet 10a. Here, as shown in FIG. 16B , the ratio (dmax / Dt) of the embedding amount dmax to the thickness Dt of the adhesive layer 20a can be calculated as the strain in response to the pressure Pf applied to the flat portion 10s when the lamination pressure Pl is applied in the compressive stress-strain curve of the adhesive layer 20a (arrow (I) in FIG. 16B ). Therefore, the value of the stress Sm corresponding to dmax / Dt in the compressive stress-strain curve of the adhesive layer 20a (arrow (II) in Figure 16C) follows the arrow (I) in Figure 16B in the reverse direction, and the stress Sm can be evaluated by the pressure Pf applied to the flat portion 10s. Figures 16B and 16C are graphs showing the compressive stress-strain curve of the adhesive layer 20a formed from the polyester adhesive composition solution A used in the examples described later, and the approximate equation y = a x x where y is the compressive stress and x is the strain. ｂ (In this example, a=278, b=2.19) As will be shown in the examples, whether or not an approximation formula is used does not have a significant effect on the calculated dmax value.

[0048] The stress F2 caused by the peel adhesive strength is evaluated using the value (Sp × sin θa) obtained by multiplying the stress Sp, which is obtained by dividing the 180° peel adhesive strength of the adhesive layer 20a to the first optical sheet 10a by the cross-sectional area of ​​the film, obtained in the 180° peel test. The stress F2 is the component of the stress Sp that is parallel to the direction in which the lamination pressure Pl is applied.

[0049] The cases are classified based on the magnitude relationship between the restoring force F1 due to compressive elasticity and the stress F2 due to peel adhesive force. (i) When the stress F2 due to peel adhesive force is equal to or greater than the restoring force F1 due to compressive elasticity (F2≧F1), the calculated embedding amount Dd=dmax. In this case, as in the example of FIG. 8B, even if the pressure P1 is removed, the embedding amount of the adhesive layer 20a into the recess 14 is considered to remain unchanged. In contrast, (ii) when the stress F2 due to peel adhesive force is smaller than the restoring force F1 due to compressive elasticity (F2<F1), the value Dd is determined by multiplying the strain corresponding to F2 in the compressive stress-strain curve of the adhesive layer 20a by the thickness Dt of the adhesive layer 20a. In other words, the calculated embedding amount Dd is determined by assuming that the strain corresponding to F2 in the compressive stress-strain curve of the adhesive layer 20a is Dd / Dt. 8A, when the pressure Pl is removed, the amount of adhesive layer 20a embedded in recess 14 decreases. As the amount of adhesive layer 20a embedded in recess 14 decreases, the restoring force due to compressive elasticity also decreases, and the amount of embedding when the restoring force due to compressive elasticity is equal to (balanced with) the stress F2 caused by the peel adhesive force is defined as Dd.

[0050] When the calculated embedding amount Dd calculated by the above method was compared with the measured value of the height of the adhesive layer 20a present in the recess 14, a certain correlation was confirmed, as shown in Fig. 17 described below. The calculated embedding amount Dd can be used to represent an optical laminate in which the intrusion of the adhesive layer 20a into the recess 14 is suppressed. Specifically, when the height (measured value) of the adhesive layer present in the recess 14 is 2 µm or less, the calculated embedding amount Dd can be expressed as 1.3 µm or less.

[0051] As described above, the optical laminate 100A according to this embodiment can be expressed as follows.

[0052] The optical laminate 100A includes a first optical sheet 10a having a first major surface 12s with a concave-convex structure and a second major surface 18s opposite the first major surface 12s, and an adhesive layer 20a disposed on the first major surface 12s side of the first optical sheet 10a. The concave-convex structure of the first major surface 12s includes a plurality of recesses 14 and flat portions 10s between adjacent recesses 14. The adhesive layer 20a contacts the flat portions 10s. The surface of the adhesive layer 20a and the first major surface 12s of the first optical sheet 10a define internal spaces 14a within each of the plurality of recesses 14. Each of the plurality of recesses 14 has an inclined surface with an inclination angle θa. The adhesive layer 20a is attached to the first major surface 12s of the first optical sheet 10a with a pressure Pl. Pf is the pressure applied to the flat portion 10s when bonding the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a. Sp is the stress obtained by dividing the 180° peel adhesive strength of the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a, as determined in a 180° peel test, by the cross-sectional area of ​​the film. When Sp×sin θa≧Pf, Dd is the value obtained by multiplying the strain corresponding to Pf in the compressive stress-strain curve of the adhesive layer 20a by the thickness Dt of the adhesive layer 20a. When Sp×sin θa<Pf, Dd is the value obtained by multiplying the strain corresponding to Sp×sin θa in the compressive stress-strain curve of the adhesive layer 20a by the thickness Dt of the adhesive layer 20a. Dd is 1.3 μm or less. In the optical laminate 100A having such a first optical sheet 10a and adhesive layer 20a, the adhesive layer 20a is prevented from embedding into the recesses 14 on the first main surface 12s of the first optical sheet.

[0053] The method for manufacturing the optical laminate 100A according to this embodiment includes Step A of preparing a first optical sheet 10a, Step B of preparing an adhesive layer 20a, and Step C of bonding the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a. Each of the multiple recesses 14 has an inclined surface with an inclination angle θa. In Step C, the pressure applied when bonding the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a is defined as Pl. In Step C, the pressure applied to the flat portion 10s when bonding the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a is defined as Pf. The stress Sp is calculated by dividing the 180° peel adhesive strength of the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a, as determined in a 180° peel test, by the cross-sectional area of ​​the film. When Sp×sin θa≧Pf, the strain corresponding to Pf in the compressive stress-strain curve of the adhesive layer 20a is multiplied by the thickness Dt of the adhesive layer 20a to obtain Dd, and when Sp×sin θa<Pf, the strain corresponding to Sp×sin θa in the compressive stress-strain curve of the adhesive layer 20a is multiplied by the thickness Dt of the adhesive layer 20a to obtain Dd, where Dd is 1.3 μm or less. In the optical laminate 100A manufactured by this method, embedding of the adhesive layer 20a into the recesses 14 of the first main surface 12s of the first optical sheet is suppressed.

[0054] The compressive stress-strain curve of the adhesive layer 20a can be obtained, for example, by the method described in the Examples. The compressive stress-strain curve of the obtained adhesive layer 20a can be calculated as y=a×x, where y is the compressive stress and x is the strain. ｂ (where a and b are positive numbers, and x indicates multiplication.) In the calculation procedure for the calculated embedment amount Dd described above, when determining the stress or strain in the compressive stress-strain curve of the adhesive layer 20a, such an approximation formula may be used (by substituting the stress (y) or strain (x) into the approximation formula), or the calculation may be performed without using the approximation formula. When an approximation formula is not used, the values ​​may be determined by selecting the closest values ​​from the measurement results (data) of the compressive stress and strain, or by appropriate interpolation.

[0055] The 180° peel adhesive strength of the adhesive layer 20a to the first main surface 12s of the first optical sheet 10a, as determined by a 180° peel test, and the stress Sp obtained by dividing this by the cross-sectional area of ​​the film, can be determined, for example, by the method described in the examples.

[0056] Among the inclined surfaces of the plurality of recesses 14, the inclined surface having the inclination angle θa directs a portion of the light propagating through the adhesive layer 20a toward the second main surface 18s of the first optical sheet 10a by total internal reflection. Each of the plurality of recesses 14 has another inclined surface (with the inclination angle θb) opposite to the inclined surface having the inclination angle θa, and the inclination angle θa is smaller than the inclination angle θb.

[0057] [Examples of preferred configurations of adhesive layer] Specific examples of adhesive layers in optical laminates according to embodiments of the present invention are listed below. The following adhesive layers Aa, Ab, and Ac are all suppressed from penetrating into the recesses of the uneven structure and from changing over time when attached to the surface of an optical sheet having an uneven structure, and are therefore suitable for use in optical laminates according to embodiments of the present invention. Note that the adhesive layers in optical laminates according to embodiments of the present invention are not limited to the following examples.

[0058] (1) Adhesive Layer Aa International Publication No. 2021 / 167090 by the present applicant describes an adhesive layer (hereinafter sometimes referred to as "adhesive layer Aa") that, in a creep test using a rotational rheometer, has a creep deformation rate of 10% or less when a stress of 10,000 Pa is applied for 1 second at 50°C, and a creep deformation rate of 16% or less when a stress of 10,000 Pa is applied for 30 minutes at 50°C, and has a 180° peel adhesive strength to a PMMA film of 10 mN / 20 mm or more. According to the applicant's studies, there is a correlation between the degree of penetration into the recesses when the adhesive layer is attached to the surface of an optical sheet having a concave-convex structure and the change over time in the degree of penetration and the creep deformation rate of the adhesive layer. Specifically, in a creep test using a rotational rheometer, an adhesive layer having a creep deformation rate of 10% or less when a stress of 10,000 Pa is applied at 50 ° C. for 1 second suppresses penetration into the recesses of the uneven structure when attached to a surface having an uneven structure, and in a creep test using a rotational rheometer, an adhesive layer having a creep deformation rate of 16% or less when a stress of 10,000 Pa is applied at 50 ° C. for 30 minutes (1800 seconds) suppresses change over time in the degree of penetration into the recesses of the uneven structure. The entire disclosure of WO 2021 / 167090 is incorporated herein by reference.

[0059] (2) Adhesive Layer Ab International Publication No. 2021 / 167091 by the present applicant discloses an adhesive layer formed by curing a curable resin of an adhesive composition containing a polymer comprising a copolymer of at least one (meth)acrylate monomer and at least one copolymerizable functional group-containing monomer selected from the group consisting of a hydroxyl group-containing copolymerizable monomer, a carboxyl group-containing copolymerizable monomer, and a nitrogen-containing vinyl monomer, and a curable resin. The adhesive layer (hereinafter sometimes referred to as "adhesive layer Ab") is described. The initial tensile modulus at 23 ° C. before curing is 0.35 MPa or more and 8.00 MPa or less, and the initial tensile modulus at 23 ° C. after curing is 1.00 MPa or more. When the adhesive composition has an initial tensile modulus of 0.35 MPa or more at 23°C before curing the curable resin, the adhesive composition is prevented from penetrating into the recesses during formation of the adhesive layer 20a, i.e., when the adhesive composition layer is applied to the first main surface 12s of the optical sheet 10a. When the adhesive composition has an initial tensile modulus of 8.00 MPa or less at 23°C before curing the curable resin of the adhesive composition, the adhesive composition layer has the softness (ease of deformation) necessary for being applied to the first main surface 12s of the optical sheet 10a. When the adhesive composition has an initial tensile modulus of 1.00 MPa or more at 23°C after curing the curable resin of the adhesive composition, the adhesive layer 20a is prevented from deforming over time and penetrating into the recesses after formation. The entire disclosure of WO 2021 / 167091 is incorporated herein by reference.

[0060] The polymer contained in the adhesive composition is, for example, a copolymer, and includes a copolymer of at least one (meth)acrylate monomer (e.g., alkyl (meth)acrylate) and at least one copolymerizable functional group-containing monomer selected from the group consisting of hydroxyl group-containing copolymerizable monomers, carboxyl group-containing copolymerizable monomers, and nitrogen-containing vinyl monomers. When the at least one copolymerizable functional group-containing monomer comprises a nitrogen-containing vinyl monomer, the weight ratio of the (meth)acrylate monomer to the nitrogen-containing vinyl monomer is, for example, between 95:5 and 50:50, between 95:5 and 55:45, between 95:5 and 60:40, between 90:10 and 50:50, between 90:10 and 55:45, between 90:10 and 60:40, between 85:15 and 50:50, between 85:15 and 55:45, between 85:15 and 60:40, between 80:20 and 50:50, between 80:20 and 55:45, between 80:20 and 60:40, between 75:25 and 50:50, between 75:25 and 55:45, or between 75:25 and 60:40, preferably between 90:10 and 60:40.

[0061] The adhesive layer Ab is formed by curing the curable resin of an adhesive composition containing a polymer and a curable resin. First, an adhesive composition layer formed from the adhesive composition is applied to the first main surface 12s of the optical sheet 10a. Next, with the adhesive composition layer applied to the first main surface 12s of the optical sheet 10a, the adhesive composition layer is heated or irradiated with active energy rays to cure the curable resin of the adhesive composition. From the viewpoint of preventing the adhesive composition layer from penetrating into the multiple recesses, it is preferable that the curable resin (e.g., ultraviolet-curable resin) have a mass average molecular weight of 4000 or more.

[0062] For example, the initial tensile modulus at 23°C before the curable resin of the adhesive composition is cured is, for example, 0.35 MPa or more, 0.40 MPa or more, 0.45 MPa or more, or 0.50 MPa or more, and is 8.00 MPa or less, 7.70 MPa or less, 7.50 MPa or less, 7.00 MPa or less, 6.50 MPa or less, 6.00 MPa or less, 5.50 MPa or less, 5.00 MPa or less, 4.50 MPa or less, 4.00 MPa or less, 3.50 MPa or less, or 3.00 MPa or less. The initial tensile modulus at 23°C after curing the curable resin of the adhesive composition is, for example, 1.00 MPa or more, 1.50 MPa or more, 2.00 MPa or more, 2.50 MPa or more, 3.00 MPa or more, 3.50 MPa or more, 4.00 MPa or more, 4.50 MPa or more, or 5.00 MPa or more. The upper limit of the initial tensile modulus at 23°C after curing the curable resin of the adhesive composition is not particularly limited, but is, for example, 1000 MPa or less, 800 MPa or less, 600 MPa or less, 400 MPa or less, or 200 MPa or less. It is more preferable that the initial tensile modulus at 23°C before curing the curable resin of the adhesive composition is 0.40 MPa or more and 7.70 MPa or less, and the initial tensile modulus at 23°C after curing the curable resin of the adhesive composition is 3.00 MPa or more.

[0063] The gel fraction of the curable resin of the adhesive composition before curing is, for example, 75% or more, and the gel fraction of the curable resin of the adhesive composition after curing is, for example, 90% or more. The upper limit of these gel fractions is not particularly limited, but is, for example, 100%.

[0064] (3) Adhesive Layer Ac International application PCT / JP2022 / 004554 by the present applicant describes an adhesive layer (hereinafter sometimes referred to as "adhesive layer Ac") formed by crosslinking an adhesive composition containing a polyester resin, which is a copolymer of a polycarboxylic acid and a polyhydric alcohol, a crosslinking agent, and at least one crosslinking catalyst selected from the group consisting of an organic zirconium compound, an organic iron compound, and an organic aluminum compound. The adhesive layer has a gel fraction of 40% or more after 300 hours at 85°C and 85% relative humidity, and a 180° peel adhesive strength to a PMMA film of 100 mN / 20 mm or more. The adhesive layer Ac can also suppress deterioration over time under high temperature and high humidity conditions. The entire disclosure of international application PCT / JP2022 / 004554 is incorporated herein by reference.

[0065] The adhesive for forming the adhesive layer Aa or the adhesive layer Ab may preferably be any of the following adhesives.

[0066] The adhesive contains, for example, a (meth)acrylic polymer, and the (meth)acrylic polymer is, for example, a copolymer of a nitrogen-containing (meth)acrylic monomer and at least one other monomer. The nitrogen-containing (meth)acrylic monomer has, for example, a nitrogen-containing cyclic structure. When the (meth)acrylic polymer is prepared using the nitrogen-containing (meth)acrylic monomer, particularly when the nitrogen-containing (meth)acrylic monomer has a nitrogen-containing cyclic structure, the elastic properties of the (meth)acrylic polymer can be improved.

[0067] When the adhesive contains a (meth)acrylic polymer, the (meth)acrylic polymer is preferably crosslinked. Furthermore, when the adhesive contains a (meth)acrylic polymer, the adhesive may further contain an active energy ray-curable resin (e.g., an ultraviolet-curable resin) and a curing agent (e.g., a photopolymerization initiator), or may further contain a cured product of the active energy ray-curable resin. The active energy ray is, for example, visible light or ultraviolet light. Introducing a crosslinked structure into the adhesive suppresses deformation during application and deformation over time of the adhesive. In particular, by applying an adhesive composition layer (that will become the adhesive layer 20a) to the optical sheet 10a and then curing the active energy ray-curable resin, deformation over time of the adhesive layer 20a can be suppressed, and the degree to which the adhesive layer 20a penetrates into recesses can be suppressed over time. Note that when the active energy ray-curable resin is cured, the adhesive layer 20a hardens. If the adhesive layer 20a is too hard, it may be difficult to bond the adhesive layer 20a to the optical sheet 10a by the roll-to-roll method, but this problem can be avoided by curing the active energy ray-curable resin after applying the adhesive composition layer to the optical sheet 10a.

[0068] The adhesive layer 20a containing a cured product of an active energy ray-curable resin is formed, for example, by the following method. First, an adhesive composition solution layer is formed from an adhesive composition solution containing a (meth)acrylic polymer, a crosslinking agent, an active energy ray-curable resin, a polymerization initiator, and a solvent. The adhesive composition solution layer is formed, for example, on a release-treated main surface of a substrate. Next, the solvent in the adhesive composition solution layer is removed, and the (meth)acrylic polymer in the adhesive composition solution layer is crosslinked with the crosslinking agent (for example, by heating) to obtain an adhesive composition layer having a crosslinked structure. When the adhesive composition solution layer is formed on the release-treated main surface of the substrate, an adhesive composition layer is formed on the release-treated main surface of the substrate, and a laminate including the substrate and the adhesive composition layer is obtained. Here, the crosslinked structure formed between the (meth)acrylic polymer and the crosslinking agent is referred to as a first crosslinked structure. This is to be distinguished from a crosslinked structure (second crosslinked structure) formed by curing an active energy ray-curable resin, as described below. The polymer in the adhesive composition solution layer may be crosslinked in the step of removing the solvent from the adhesive composition solution layer, or a step of crosslinking the polymer in the adhesive composition solution layer may be performed after the step of removing the solvent from the adhesive composition solution layer, separately from the step of removing the solvent from the adhesive composition solution layer. The adhesive composition layer is then attached to the first main surface 12 s of the optical sheet 10 a, and while the adhesive composition layer is disposed on the first main surface 12 s of the optical sheet 10 a, the adhesive composition layer is irradiated with active energy rays to cure the active energy ray-curable resin, thereby forming an adhesive layer 20 a having a second crosslinked structure in addition to a first crosslinked structure. The first crosslinked structure and the second crosslinked structure in the adhesive layer 20 a are considered to form a so-called interpenetrating network structure (IPN).

[0069] The adhesive layer 20a, which does not contain a cured product of an active energy ray-curable resin, is formed, for example, by the following method. First, an adhesive composition solution layer is formed from an adhesive composition solution containing a polymer, a crosslinking agent, and a solvent. This adhesive composition solution does not contain an active energy ray-curable resin or a polymerization initiator. The adhesive composition solution layer is formed, for example, on a release-treated main surface of a substrate. Next, the solvent in the adhesive composition solution layer is removed, and the polymer in the adhesive composition solution layer is crosslinked with a crosslinking agent (for example, by heating), thereby obtaining an adhesive layer 20a having a crosslinked structure. When the adhesive composition solution layer is formed on the release-treated main surface of the substrate, an adhesive layer is formed on the release-treated main surface of the substrate, and a laminate having the substrate and the adhesive layer is obtained. The polymer in the adhesive composition solution layer may be crosslinked in the step of removing the solvent from the adhesive composition solution layer, or a step of crosslinking the polymer in the adhesive composition solution layer may be further performed after the step of removing the solvent from the adhesive composition solution layer, separately from the step of removing the solvent from the adhesive composition solution layer.

[0070] The adhesive preferably does not contain a graft polymer. If the adhesive layer is formed from an adhesive composition containing a graft polymer, as in the adhesive layer described in Patent Document 1, the number of design and control factors for the material increases, which may result in poor mass productivity. Adhesives that do not contain a graft polymer can adjust the creep properties by various factors (e.g., the type and amount of crosslinking agent, the type and amount of actinic radiation-curable resin).

[0071] Specific examples of suitable adhesives are described below.

[0072] The adhesive includes, for example, a (meth)acrylic polymer. The monomer used to produce the (meth)acrylic polymer may be any (meth)acrylate, and is not particularly limited. For example, an alkyl (meth)acrylate having an alkyl group with 4 or more carbon atoms may be used. In this case, the proportion of the alkyl (meth)acrylate having an alkyl group with 4 or more carbon atoms relative to the total amount of monomers used to produce the (meth)acrylic polymer is, for example, 50% by mass or more.

[0073] In this specification, "alkyl(meth)acrylate" refers to a (meth)acrylate having a linear or branched alkyl group. The number of carbon atoms in the alkyl group of the alkyl(meth)acrylate is preferably 4 or more, and more preferably 4 to 9. Note that (meth)acrylate refers to acrylate and / or methacrylate.

[0074] Specific examples of alkyl (meth)acrylates include n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate. acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate, isomyristyl (meth)acrylate, n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, etc. These can be used alone or in combination.

[0075] The adhesive may contain a (meth)acrylic polymer which is a copolymer of a nitrogen-containing (meth)acrylic monomer and at least one other monomer. In this case, the (meth)acrylic polymer is preferably a copolymer obtained by copolymerizing the following monomers in the following amounts, where the total amount of the monomers used in the copolymerization is taken as 100 parts by mass:

[0076] Nitrogen-containing (meth)acrylic monomer: 10.0 parts by mass or more, 15.0 parts by mass or more, 20.0 parts by mass or more, 25.0 parts by mass or more, 30.0 parts by mass or more, or 35.0 parts by mass or more, and 40.0 parts by mass or less, 35.0 parts by mass or less, 30.0 parts by mass or less, 25.0 parts by mass or less, 20.0 parts by mass or less, or 15.0 parts by mass or less, for example, 10.0 parts by mass or more and 40.0 parts by mass or less.

[0077] Hydroxyl group-containing acrylic monomer: 0.05 parts by mass or more, 0.75 parts by mass or more, 1.0 parts by mass or more, 2.0 parts by mass or more, 3.0 parts by mass or more, 4.0 parts by mass or more, 5.0 parts by mass or more, 6.0 parts by mass or more, 7.0 parts by mass or more, 8.0 parts by mass or more, or 9.0 parts by mass or more, and 10.0 parts by mass or less, 9.0 parts by mass or less, 8.0 parts by mass or less, 7.0 parts by mass or less, 6.0 parts by mass or less, 5.0 parts by mass or less, 4.0 parts by mass or less, 3.0 parts by mass or less, 2.0 parts by mass or less, or 1.0 parts by mass or less. For example, 0.05 parts by mass or more and 10.0 parts by mass or less.

[0078] Carboxyl group-containing acrylic monomer: 1.0 part by mass or more, 2.0 parts by mass or more, 3.0 parts by mass or more, 4.0 parts by mass or more, 5.0 parts by mass or more, 6.0 parts by mass or more, 7.0 parts by mass or more, 8.0 parts by mass or more, or 9.0 parts by mass or more, and 10.0 parts by mass or less, 9.0 parts by mass or less, 8.0 parts by mass or less, 7.0 parts by mass or less, 6.0 parts by mass or less, 5.0 parts by mass or less, 4.0 parts by mass or less, 3.0 parts by mass or less, or 2.0 parts by mass or less, for example, 1.0 part by mass or more and 10.0 parts by mass or less.

[0079] Alkyl (meth)acrylate monomer: (100 parts by mass) - (total amount of monomers other than alkyl (meth)acrylate monomers used in copolymerization)

[0080] In this specification, the term "nitrogen-containing (meth)acrylic monomer" includes, without particular limitation, a monomer having a polymerizable functional group with an unsaturated double bond of a (meth)acryloyl group and having a nitrogen atom. The "nitrogen-containing (meth)acrylic monomer" has, for example, a nitrogen-containing cyclic structure. Examples of nitrogen-containing (meth)acrylic monomers having a nitrogen-containing cyclic structure include N-vinyl-2-pyrrolidone (NVP), N-vinyl-ε-caprolactam (NVC), and 4-acryloylmorpholine (ACMO). These can be used alone or in combination.

[0081] In this specification, the term "hydroxyl group-containing acrylic monomer" includes, without particular limitation, a monomer having a polymerizable functional group with an unsaturated double bond of a (meth)acryloyl group and also having a hydroxyl group. Examples include hydroxyalkyl (meth)acrylates such as 2-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; 4-hydroxymethylcyclohexyl (meth)acrylate, and 4-hydroxybutyl vinyl ether.

[0082] In this specification, the term "carboxyl group-containing acrylic monomer" includes, without limitation, a monomer having a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also having a carboxyl group. Examples of unsaturated carboxylic acid-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. These can be used alone or in combination.

[0083] The adhesive may contain a (meth)acrylic polymer which is a copolymer of a carboxyl group-containing acrylic monomer and at least one other monomer (excluding nitrogen-containing (meth)acrylic monomers). In this case, the (meth)acrylic polymer is preferably a copolymer obtained by copolymerizing the following monomers in the following amounts, where the total amount of the monomers used in the copolymerization is taken as 100 parts by mass:

[0084] Carboxyl group-containing acrylic monomer: 1.0 part by mass or more, 2.0 parts by mass or more, 3.0 parts by mass or more, 4.0 parts by mass or more, 5.0 parts by mass or more, 6.0 parts by mass or more, 7.0 parts by mass or more, 8.0 parts by mass or more, or 9.0 parts by mass or more, and 10.0 parts by mass or less, 9.0 parts by mass or less, 8.0 parts by mass or less, 7.0 parts by mass or less, 6.0 parts by mass or less, 5.0 parts by mass or less, 4.0 parts by mass or less, 3.0 parts by mass or less, or 2.0 parts by mass or less, for example, 1.0 part by mass or more and 10.0 parts by mass or less.

[0085] Alkyl (meth) acrylate monomer: 90.0 parts by mass or more, 91.0 parts by mass or more, 92.0 parts by mass or more, 93.0 parts by mass or more, 94.0 parts by mass or more, 95.0 parts by mass or more, 96.0 parts by mass or more, 97.0 parts by mass or more, or 98.0 parts by mass or more, and 99.0 parts by mass or less, 98.0 parts by mass or less, 97.0 parts by mass or less, 96.0 parts by mass or less, 95.0 parts by mass or less, 94.0 parts by mass or less, 93.0 parts by mass or less, 92.0 parts by mass or less, or 91.0 parts by mass or less. For example, 90.0 parts by mass or more and 99.0 parts by mass or less.

[0086] Examples of crosslinking agents that introduce a crosslinked structure into the (meth)acrylic polymer include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, peroxides, etc. The crosslinking agents can be used alone or in combination of two or more.

[0087] The isocyanate crosslinking agent refers to a compound having two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate groups are temporarily protected by a blocking agent or oligomerization) in one molecule.

[0088] Examples of the isocyanate crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

[0089] More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name: Coronate L), trimethylolpropane / hexamethylene diisocyanate trimer adduct ( Examples of suitable polyisocyanates include isocyanate adducts such as an isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation, trade name: Coronate HL), an adduct of xylylene diisocyanate with trimethylolpropane (manufactured by Mitsui Chemicals, Inc., trade name: D110N), and an adduct of hexamethylene diisocyanate with trimethylolpropane (manufactured by Mitsui Chemicals, Inc., trade name: D160N); polyether polyisocyanates, polyester polyisocyanates, and adducts of these with various polyols; and polyisocyanates multifunctionalized with isocyanurate bonds, biuret bonds, allophanate bonds, etc.

[0090] The isocyanate crosslinking agent may be used alone or in combination of two or more. The amount of the isocyanate crosslinking agent is, for example, 0.01 parts by mass or more, 0.02 parts by mass or more, 0.05 parts by mass or more, or 0.1 parts by mass or more, and 10 parts by mass or less, 9 parts by mass or less, 8 parts by mass or less, 7 parts by mass or less, 6 parts by mass or less, or 5 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer, and preferably 0.01 parts by mass or more and 10 parts by mass or less, 0.02 parts by mass or more and 9 parts by mass or less, or 0.05 parts by mass or more and 8 parts by mass or less. The amount may be appropriately adjusted taking into consideration the cohesive strength, prevention of peeling in durability tests, etc.

[0091] In addition, in the aqueous dispersion of the modified (meth)acrylic polymer prepared by emulsion polymerization, it is not necessary to use an isocyanate-based crosslinking agent, but if necessary, a blocked isocyanate-based crosslinking agent can be used because it easily reacts with water.

[0092] The epoxy crosslinking agent is a polyfunctional epoxy compound having two or more epoxy groups in one molecule. Examples of the epoxy crosslinking agent include bisphenol A, epichlorohydrin-type epoxy resin, ethylene glycidyl ether, N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, diamine glycidylamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and sorbitol. Examples of the epoxy crosslinking agent include polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, and bisphenol-S-diglycidyl ether, as well as epoxy resins having two or more epoxy groups in the molecule. Examples of the epoxy crosslinking agent that can be used include products manufactured by Mitsubishi Gas Chemical Company, Inc., under the trade names "Tetrad C" and "Tetrad X."

[0093] The epoxy crosslinking agent may be used alone or in combination of two or more. The amount of the epoxy crosslinking agent is, for example, 0.01 parts by mass or more, 0.02 parts by mass or more, 0.05 parts by mass or more, or 0.1 parts by mass or more, and 10 parts by mass or less, 9 parts by mass or less, 8 parts by mass or less, 7 parts by mass or less, 6 parts by mass or less, or 5 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic polymer, and preferably 0.01 parts by mass or more and 10 parts by mass or less, 0.02 parts by mass or more and 9 parts by mass or less, or 0.05 parts by mass or more and 8 parts by mass or less. The amount may be appropriately adjusted taking into consideration the cohesive strength, prevention of peeling in durability tests, etc.

[0094] Any peroxide crosslinking agent can be used as long as it generates radical active species when heated and promotes crosslinking of the base polymer of the adhesive. However, taking into consideration workability and stability, it is preferable to use a peroxide whose 1-minute half-life temperature is 80°C or higher and 160°C or lower, and it is more preferable to use a peroxide whose 1-minute half-life temperature is 90°C or higher and 140°C or lower.

[0095] Examples of peroxides include di(2-ethylhexyl)peroxydicarbonate (1-minute half-life temperature: 90.6°C), di(4-t-butylcyclohexyl)peroxydicarbonate (1-minute half-life temperature: 92.1°C), di-sec-butylperoxydicarbonate (1-minute half-life temperature: 92.4°C), t-butylperoxyneodecanoate (1-minute half-life temperature: 103.5°C), t-hexylperoxypivalate (1-minute half-life temperature: 109.1°C), t-butylperoxypivalate (1-minute half-life temperature: 110.3°C), dilauroyl peroxide (1 1-minute half-life temperature: 116.4°C), di-n-octanoyl peroxide (1-minute half-life temperature: 117.4°C), 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (1-minute half-life temperature: 124.3°C), di(4-methylbenzoyl)peroxide (1-minute half-life temperature: 128.2°C), dibenzoyl peroxide (1-minute half-life temperature: 130.0°C), t-butylperoxyisobutyrate (1-minute half-life temperature: 136.1°C), 1,1-di(t-hexylperoxy)cyclohexane (1-minute half-life temperature: 149.2°C), and the like. Among these, di(4-t-butylcyclohexyl)peroxydicarbonate (1-minute half-life temperature: 92.1°C), dilauroyl peroxide (1-minute half-life temperature: 116.4°C), dibenzoyl peroxide (1-minute half-life temperature: 130.0°C), and the like are preferably used because they have particularly excellent crosslinking reaction efficiency.

[0096] The half-life of a peroxide is an index showing the decomposition rate of the peroxide, and refers to the time until the remaining amount of the peroxide is reduced to half. The decomposition temperature for obtaining the half-life at any time and the half-life time at any temperature are described in manufacturer catalogs, for example, in NOF Corporation's "Organic Peroxide Catalog, 9th Edition (May 2003)."

[0097] The peroxide may be used alone or in combination of two or more. The amount of peroxide to be added is 0.02 to 2 parts by mass, preferably 0.05 to 1 part by mass, per 100 parts by mass of the (meth)acrylic polymer. The amount is appropriately adjusted within this range to adjust processability, reworkability, crosslinking stability, peelability, etc.

[0098] The amount of decomposed peroxide remaining after the reaction treatment can be measured, for example, by HPLC (high performance liquid chromatography).

[0099] More specifically, for example, about 0.2 g of the PSA after the reaction treatment is taken out, immersed in 10 ml of ethyl acetate, and extracted by shaking at 120 rpm for 3 hours in a shaker at 25°C, and then allowed to stand at room temperature for 3 days. Next, 10 ml of acetonitrile is added, and the mixture is shaken at 120 rpm for 30 minutes at 25°C. About 10 μl of the extract obtained by filtering through a membrane filter (0.45 μm) is injected into HPLC for analysis, and the amount of peroxide after the reaction treatment can be determined.

[0100] In addition, an organic crosslinking agent or a polyfunctional metal chelate may be used in combination as the crosslinking agent. The polyfunctional metal chelate is a compound in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Examples of atoms in the organic compound that form covalent or coordinate bonds include oxygen atoms, and examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

[0101] The amount of active energy ray-curable resin blended is, for example, 3 parts by mass or more and 60 parts by mass or less relative to 100 parts by mass of the (meth)acrylic polymer. The mass average molecular weight (Mw) before curing is 4,000 or more and 50,000 or less. As the active energy ray-curable resin, for example, an acrylate-based, epoxy-based, urethane-based, or ene-thiol-based ultraviolet-curable resin can be suitably used.

[0102] As the active energy ray-curable resin, a monomer and / or oligomer that undergoes radical polymerization or cationic polymerization upon exposure to active energy rays is used.

[0103] Examples of monomers that undergo radical polymerization upon exposure to active energy rays include monomers having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group, and monomers having a (meth)acryloyl group are particularly preferred due to their excellent reactivity.

[0104] Specific examples of the monomer having a (meth)acryloyl group include allyl (meth)acrylate, caprolactone (meth)acrylate, cyclohexyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, heptadecafluorodecyl (meth)acrylate, glycidyl (meth)acrylate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, isobornyl (meth)acrylate, morpholine (meth)acrylate, phenoxyethyl (meth)acrylate, tripropylene glycol di(

[0043] Examples of the di(meth)acrylate include hydroxypivalic acid neopentyl glycol di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethoxy tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0105] Examples of oligomers that undergo radical polymerization by active energy rays include polyester (meth)acrylates, epoxy (meth)acrylates, and urethane (meth)acrylates, which have two or more unsaturated double bonds, such as (meth)acryloyl groups and vinyl groups, added to a backbone of polyester, epoxy, urethane, or the like, as functional groups similar to those of monomers.

[0106] Polyester (meth)acrylate is obtained by reacting a polyester having terminal hydroxyl groups, which is obtained from a polyhydric alcohol and a polycarboxylic acid, with (meth)acrylic acid. Specific examples include the Aronix M-6000, 7000, 8000, and 9000 series manufactured by Toa Gosei Co., Ltd.

[0107] Epoxy (meth)acrylates are obtained by reacting epoxy resins with (meth)acrylic acid, and specific examples include Lipoxy SP and VR series manufactured by Showa Highpolymer Co., Ltd. and Epoxy Ester series manufactured by Kyoeisha Chemical Co., Ltd.

[0108] Urethane (meth)acrylates are obtained by reacting polyols, isocyanates, and hydroxy (meth)acrylates, and specific examples include the Art Resin UN series manufactured by Negami Chemical Industrial Co., Ltd., the NK Oligo U series manufactured by Shin-Nakamura Chemical Co., Ltd., and the Shiko UV series manufactured by Mitsubishi Chemical Corporation.

[0109] The photopolymerization initiator is excited and activated by irradiation with ultraviolet light to generate radicals, and has the effect of curing the polyfunctional oligomer by radical polymerization. Examples thereof include 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexylphenyl acetophenone-based photopolymerization initiators such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-2-phenylacetophenone; benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, and hydroxybenzophenone. benzophenone-based photopolymerization initiators such as 4-benzoyl-4'-methyldiphenyl sulfide and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone-based photopolymerization initiators such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone and 2,4-diisopropylthioxanthone; α-acyloxime esters; acylphosphines Examples of photopolymerization initiators that can be used include special photopolymerization initiators such as methylphenylglyoxylate, benzil, camphorquinone, dibenzosuberone, 2-ethylanthraquinone, and 4',4"-diethylisophthalophenone. Furthermore, photocationic polymerization initiators such as allylsulfonium hexafluorophosphate salts, sulfonium hexafluorophosphate salts, and bis(alkylphenyl)iodonium hexafluorophosphate can also be used.

[0110] Two or more of the photopolymerization initiators can be used in combination. The polymerization initiator is typically blended in an amount of 0.5 to 30 parts by weight, preferably 1 to 20 parts by weight, per 100 parts by weight of the active energy ray-curable resin. If the amount is less than 0.5 parts by weight, polymerization will not proceed sufficiently, slowing down the curing rate. If the amount exceeds 30 parts by weight, problems such as a decrease in the hardness of the cured sheet may occur.

[0111] The active energy ray is not particularly limited, but is preferably ultraviolet light, visible light, or an electron beam. The crosslinking treatment by ultraviolet irradiation can be carried out using an appropriate ultraviolet light source such as a high-pressure mercury lamp, a low-pressure mercury lamp, an excimer laser, a metal halide lamp, or an LED lamp. In this case, the irradiation dose of ultraviolet light can be appropriately selected depending on the required degree of crosslinking, but typically, for ultraviolet light, the dose is 0.2 J / cm. 2 More than 10J / cm 2 It is desirable to select the temperature within the following range: The temperature during irradiation is not particularly limited, but is preferably up to about 140° C. in consideration of the heat resistance of the support.

[0112] When the adhesive contains a polyester polymer instead of or together with a (meth)acrylic polymer, for example, a polyester polymer having the following characteristics is preferred.

[0113] The type of carboxylic acid component (or skeletal characteristics, etc.): The dicarboxylic acid contains at least two carboxyl groups, specifically, a dicarboxylic acid. The dicarboxylic acid is not particularly limited, but examples include dimer acids derived from sebacic acid, oleic acid, and erucic acid. Other examples include aliphatic or alicyclic dicarboxylic acids such as glutaric acid, suberic acid, adipic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, dodecenylsuccinic anhydride, fumaric acid, succinic acid, dodecanedioic acid, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, itaconic acid, and citraconic acid; and terephthalic acid, isophthalic acid, orthophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, and 4,4'-diphenyletherdicarboxylic acid. In addition to the dicarboxylic acids mentioned above, tricarboxylic acids containing three or more carboxyl groups can also be used.

[0114] Type of diol component (or skeletal characteristics, etc.): Contains at least one having two hydroxyl groups in the molecule, specifically diol. Examples include fatty acid esters, dimer diols derived from oleic acid, erucic acid, etc., and glycerol monostearate. Other examples include aliphatic glycols such as ethylene glycol and 1,2-propylene glycol, and, other than aliphatic glycols, ethylene oxide adducts and propylene oxide adducts of bisphenol A, and ethylene oxide adducts and propylene oxide adducts of hydrogenated bisphenol A.

[0115] Examples of crosslinking agents that can be used to introduce a crosslinked structure into the polyester polymer include isocyanate-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl-etherified melamine-based crosslinking agents, and metal chelate-based crosslinking agents. The blending amount is, for example, 2.0 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the polyester polymer.

[0116] Specific examples of the composition of the adhesive layer Ac will be described below.

[0117] <Polycarboxylic Acid> Examples of polycarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, benzylmalonic acid, diphenic acid, 4,4'-oxydibenzoic acid, and naphthalenedicarboxylic acid; aliphatic dicarboxylic acids such as malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, thiodipropionic acid, and diglycolic acid; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, and adamantanedicarboxylic acid; and the like. These may be used alone or in combination of two or more.

[0118] Among these, from the viewpoint of imparting cohesive strength, it is preferable to contain an aromatic dicarboxylic acid, and it is particularly preferable to contain terephthalic acid or isophthalic acid.

[0119] <Polyhydric Alcohols> Examples of polyhydric alcohols include aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, and polytetramethylene glycol; Alicyclic diols such as 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecane dimethanol, adamantanediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol; aromatic diols such as 4,4'-thiodiphenol, 4,4'-methylenediphenol, 4,4'-dihydroxybiphenyl, o-, m-, and p-dihydroxybenzene, 2,5-naphthalenediol, p-xylenediol, and ethylene oxide and propylene oxide adducts thereof; etc. These can be used alone or in combination of two or more.

[0120] Among these, it is preferable to contain an aliphatic diol or an alicyclic diol, and it is more preferable to contain polytetramethylene glycol, neopentyl glycol or cyclohexanedimethanol.

[0121] <Crosslinking Agent> The crosslinking agent is not particularly limited, and known crosslinking agents can be used, such as polyisocyanurates, polyfunctional isocyanates, polyfunctional melamine compounds, polyfunctional epoxy compounds, polyfunctional oxazoline compounds, polyfunctional aziridine compounds, metal chelate compounds, etc. In particular, from the viewpoint of obtaining transparency of the adhesive layer to be obtained and an elastic modulus suitable for the adhesive layer, it is preferable to use an isocyanate-based crosslinking agent.

[0122] The isocyanate crosslinking agent refers to a compound having two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate groups are temporarily protected by a blocking agent or oligomerization) in one molecule.

[0123] Examples of the isocyanate crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

[0124] More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate; trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name: Coronate L), trimethylolpropane / hexamethylene diisocyanate trimer adduct ( Examples of suitable isocyanate adducts include those manufactured by Tosoh Corporation (trade name: Coronate HL), those manufactured by Tosoh Corporation (trade name: Coronate HX), and those manufactured by Mitsui Chemicals, Inc. (trade name: D110N), and those manufactured by Mitsui Chemicals, Inc. (trade name: D160N). These include polyether polyisocyanates, polyester polyisocyanates, and adducts of these with various polyols, and polyisocyanates multifunctionalized with isocyanurate bonds, biuret bonds, allophanate bonds, etc. Aliphatic isocyanates are preferred because they allow for the production of an adhesive layer with a high gel fraction using a small amount of crosslinker.

[0125] The isocyanate-based crosslinking agent may be used alone or in combination of two or more. The lower limit of the amount of the isocyanate-based crosslinking agent is 6 parts by mass or more, preferably 7 parts by mass or more, 8 parts by mass or more, 9 parts by mass or more, or 10 parts by mass or more, relative to 100 parts by mass of the polyester resin, and the upper limit of the amount of the isocyanate-based crosslinking agent is 20 parts by mass or less, preferably 15 parts by mass or less. By keeping the amount within this range, it is possible to maintain good adhesion to a surface having an uneven structure while preventing the adhesive layer from penetrating into the recesses of the uneven structure over time.

[0126] <Crosslinking Catalyst> Examples of organoaluminum compounds include aluminum trisacetylacetonate, aluminum trisethylacetoacetate, and diisopropoxyaluminum ethylacetoacetate.

[0127] Examples of organic iron compounds include acetylacetone-iron complexes.

[0128] The organic zirconium compound may include zirconium tetraacetylacetonate.

[0129] These may be used alone or in combination of two or more types as required.

[0130] The use of a crosslinking catalyst can increase the crosslinking rate and shorten the production lead time.

[0131] Known methods can be used to form the adhesive layer Ac. Examples include the following: First, an adhesive composition (or a solution containing the adhesive composition) is applied (coated) onto a support (substrate) and dried as needed to form an adhesive composition layer. Typically, an adhesive composition solution containing a polyester resin, a crosslinking agent, a crosslinking catalyst, and a solvent is applied onto the substrate to form an adhesive composition solution layer on the substrate, and the solvent is removed from the adhesive composition solution layer to obtain an adhesive composition layer. Next, the adhesive composition layer is subjected to a crosslinking treatment (e.g., heat treatment) to crosslink the polyester resin in the adhesive composition layer with the crosslinking agent, thereby forming an adhesive layer having a crosslinked structure. In this way, an adhesive layer is formed on the substrate, and a laminate having the substrate and adhesive layer is obtained. For example, a substrate having a release-treated main surface, such as a release liner, may be used as the substrate. The adhesive layer formed on the release liner by the above method may be transferred (transferred) onto a support (or another release liner). Known methods can be used to apply the adhesive composition (adhesive composition solution) onto a substrate. For example, roll coating, gravure coating, reverse roll coating, roll brush coating, air knife coating, spray coating, extrusion coating using a die coater, etc. may be mentioned.

[0132] [Examples of Preferred Configurations of Light Guide Layer, Optical Sheet, Base Layer, and Low Refractive Index Layer] Preferred examples of each component of the lighting device according to the embodiment of the present invention will be described.

[0133] The light guide layer 80 can be formed of a known material with high transmittance for visible light. The light guide layer 80 is formed of, for example, an acrylic resin such as polymethyl methacrylate (PMMA), a polycarbonate (PC) resin, a cycloolefin resin, or glass (for example, quartz glass, alkali-free glass, or borosilicate glass). The refractive index n of the light guide layer 80 is ＧＰ is, for example, 1.40 or more and 1.80 or less. Unless otherwise specified, the refractive index refers to a refractive index measured with an ellipsometer at a wavelength of 550 nm. The thickness of the light-guiding layer 80 can be set appropriately depending on the application. The thickness of the light-guiding layer 80 is, for example, 0.05 mm or more and 50 mm or less.

[0134] The first optical sheet 10a can be produced by, for example, the method described in JP-A-2013-524288. Specifically, for example, the surface of a polymethyl methacrylate (PMMA) film is coated with lacquer (for example, Finecure RM-64 manufactured by Sanyo Chemical Industries, Ltd.: an acrylate-based photocurable resin), an optical pattern is embossed on the film surface containing the lacquer, and then the lacquer is cured (for example, ultraviolet irradiation conditions: D bulb, 1000 mJ / cm ２ , 320 mW / cm ２ ) to produce the first optical sheet 10a.

[0135] Examples of materials for the second optical sheet 30 include optically transparent thermoplastic resins, and more specifically, films formed from (meth)acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resins, etc. Any appropriate material can be used for the second optical sheet 30 depending on the purpose.

[0136] The thickness of the substrate layer is, for example, 1 μm to 1000 μm, preferably 10 μm to 100 μm, and more preferably 20 μm to 80 μm. The refractive index of the substrate layer is preferably 1.40 to 1.70, and more preferably 1.43 to 1.65.

[0137] Refractive index n of the low refractive index layer Ｌ１ are each independently, for example, preferably 1.30 or less, more preferably 1.20 or less, and even more preferably 1.15 or less. The low refractive index layer is preferably solid, and the refractive index is, for example, 1.05 or more. The difference between the refractive index of the light guide layer 80 and the refractive index of the low refractive index layer is preferably 0.20 or more, more preferably 0.23 or more, and even more preferably 0.25 or more. A low refractive index layer having a refractive index of 1.30 or less can be formed using, for example, a porous material. The thickness of each low refractive index layer is, for example, independently, 0.3 μm or more and 5 μm or less.

[0138] When the low refractive index layer is a porous material having voids therein, the porosity is preferably 35 vol% or more, more preferably 38 vol% or more, and particularly preferably 40 vol% or more. Within this range, a low refractive index layer with a particularly low refractive index can be formed. The upper limit of the porosity of the low refractive index layer is, for example, 90 vol% or less, preferably 75 vol% or less. Within this range, a low refractive index layer with excellent strength can be formed. The porosity is a value calculated from the refractive index measured with an ellipsometer using the Lorentz-Lorenz formula.

[0139] The low refractive index layer may be, for example, a voided low refractive index layer as disclosed in International Publication No. 2019 / 146628. The entire disclosure of International Publication No. 2019 / 146628 is incorporated herein by reference. Specifically, the voided low refractive index layer includes substantially spherical particles such as silica particles, microporous silica particles, hollow silica nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, and silica nanofibers, and flat particles such as nanoclay composed of bentonite. In one embodiment, the voided low refractive index layer is a porous body formed by direct chemical bonding of particles (e.g., microporous particles). Furthermore, at least a portion of the particles constituting the voided low refractive index layer may be bonded to each other via a small amount (e.g., less than the mass of the particles) of a single binder component. The porosity and refractive index of the low refractive index layer can be adjusted by the particle size, particle size distribution, etc. of the particles constituting the low refractive index layer.

[0140] Methods for obtaining a low refractive index layer having voids include, for example, methods described in JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, WO 2004 / 113966 A, and references thereto. The disclosures of JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, and WO 2004 / 113966 A are incorporated herein by reference in their entirety.

[0141] A porous silica body can be suitably used as the low refractive index layer having voids. The porous silica body can be produced by, for example, the following methods. Examples include a method of hydrolyzing and polycondensing a silicon compound; hydrolyzable silanes and / or silsesquioxane, and at least one of their partial hydrolyzates and dehydration condensates; a method using porous particles and / or hollow microparticles; a method of producing an aerogel layer by utilizing the springback phenomenon; and a method using a pulverized gel in which a gel-like silicon compound obtained by a sol-gel method is pulverized and the resulting pulverized microporous particles are chemically bonded together with a catalyst or the like. However, the low refractive index layer is not limited to a porous silica body, and the production method is not limited to the exemplified methods, and any production method may be used. However, the porous layer is not limited to a porous silica body, and the production method is not limited to the exemplified methods, and any production method may be used. The silsesquioxane may be (RSiO １．５ , R is a hydrocarbon group) as a basic structural unit, and ２ Although it is strictly different from silica, which has silsesquioxane as a basic structural unit, it has something in common with silica in that it has a network structure cross-linked by siloxane bonds. Therefore, in this specification, porous materials containing silsesquioxane as a basic structural unit are also referred to as porous silica materials or silica-based porous materials.

[0142] The porous silica material can be composed of microporous particles of a gel-like silicon compound bonded to one another. Examples of the microporous particles of the gel-like silicon compound include pulverized gel-like silicon compounds. The porous silica material can be formed, for example, by applying a coating liquid containing pulverized gel-like silicon compounds to a substrate. The pulverized gel-like silicon compounds can be chemically bonded (e.g., siloxane bonded) by, for example, the action of a catalyst, light irradiation, heating, etc.

[0143] Example 1 (1) Preparation of Polyester Resin A A four-neck separable flask was equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a cooling tube with a trap. 47 g of terephthalic acid (molecular weight: 166) and 45 g of isophthalic acid (molecular weight: 166) as carboxylic acid components, 115 g of polytetramethylene glycol (molecular weight: 566), 4 g of ethylene glycol (molecular weight: 62), 16 g of neopentyl glycol (molecular weight: 104), and 23 g of cyclohexanedimethanol (molecular weight: 144) as alcohol components, and 0.1 g of tetrabutyl titanate as a catalyst were added to the flask. The flask was filled with nitrogen gas, and the mixture was heated to 240°C with stirring, and maintained at 240°C for 4 hours.

[0144] Thereafter, the nitrogen inlet tube and the cooling tube with a trap were removed, and replaced with a vacuum pump. The mixture was heated to 240°C while stirring in a reduced pressure atmosphere (0.002 MPa) and maintained at 240°C. The reaction was continued for approximately 6 hours to obtain polyester resin A. Polyester resin A was obtained by polymerizing the above monomers without using a solvent. The weight average molecular weight (Mw) of polyester resin A measured by GPC was 59,200. The prepared polyester resin A was taken out of the flask while being dissolved in ethyl acetate to prepare a polyester resin A solution with a solids concentration of 50% by mass.

[0145] (2) Preparation of Adhesive Composition Solution For 100 parts by mass of the solids content of the polyester resin A solution prepared above, 0.07 parts by mass of zirconium tetraacetylacetonate (trade name "Orgatix ZC-162", manufactured by Matsumoto Fine Chemical Co., Ltd.; "Orgatix" is a registered trademark; hereinafter, sometimes referred to as "ZC-162") as a crosslinking catalyst, 12 parts by mass of an isocyanurate of hexamethylene diisocyanate (trade name "Coronate HX", manufactured by Tosoh Corporation; "Coronate" is a registered trademark; hereinafter, sometimes referred to as "Coronate HX") as a crosslinking agent, and 20 parts by mass of acetylacetone as a catalytic reaction inhibitor were blended, and ethyl acetate was further added so that the solids concentration was 20% by mass to prepare an adhesive composition solution (sometimes referred to as "polyester adhesive composition solution A").

[0146] (3) Preparation of Adhesive Sheet The adhesive composition solution was applied to one side of a silicone release-treated substrate (first separator) to form an adhesive composition solution layer. A 38 μm-thick polyethylene terephthalate (PET) film (trade name "MRF38" manufactured by Mitsubishi Chemical Corporation) was used as the first separator. The adhesive composition solution layer was applied so that the thickness of the adhesive layer would be 10 μm after the process of treating at 40°C for 3 days described below. The adhesive composition solution layer was dried at 150°C for 1 minute to remove the solvent from the adhesive composition solution layer, thereby obtaining an adhesive composition layer. Next, the adhesive composition layer was attached to the release-treated surface of another silicone release-treated substrate (second separator) and left at 40°C for 3 days. A 75 μm-thick biaxially oriented polyethylene terephthalate film (trade name: Diafoil T302 manufactured by Mitsubishi Chemical Corporation, hereinafter sometimes referred to as "T302") was used as the second separator. The adhesive composition layer was treated at 40°C for 3 days to crosslink the polyester resin A in the adhesive composition layer with the crosslinking agent, thereby forming an adhesive layer. In this way, an adhesive sheet (laminate) having a laminate structure of first separator (PET film) / adhesive layer / second separator (PET film) was produced. Although partial crosslinking of the polyester resin A may occur in the step of treating the adhesive composition solution layer at 150°C for 1 minute, the majority of the crosslinking reaction occurs in the subsequent step of heat treatment at 40°C for 3 days.

[0147] (4) Production of Textured Film A Textured film A was produced according to the method described in JP-A 2013-524288. Specifically, the surface of a polymethyl methacrylate (PMMA) film was coated with lacquer (Finecure RM-64, manufactured by Sanyo Chemical Industries, Ltd.), an optical pattern was embossed on the film surface containing the lacquer, and then the lacquer was cured to produce the desired textured film. The total thickness of the textured film A was 130 μm, and the haze value was 0.8%.

[0148] FIG. 9A shows a plan view of a portion of the produced unevenly shaped film A as seen from the uneven surface side as an unevenly shaped film 70. FIG. 9B also shows a 9B-9B' cross-sectional view of the unevenly shaped film 70 of FIG. 9A. A plurality of recesses 74 having a length L of 86 μm, a width W of 9.2 μm, and a depth H of 10 μm and a triangular cross section were arranged at intervals of width E (155 μm) in the X-axis direction. Furthermore, such a pattern of recesses 74 was arranged at intervals of width D (100 μm) in the Y-axis direction. The pitch Px of the recesses 74 in the X-axis direction was 241 μm (Px = L + E), and the pitch Py in the Y-axis direction was 109.2 μm (Py = W + D). The density of the recesses 74 on the unevenly shaped film surface was 3612 / cm ２ 9B, the inclination angle θa was 49°, the inclination angle θb was 85°, and the occupied area ratio Rr of the recesses 74 when the film was viewed in plan from the uneven surface side was 4.05%.

[0149] (5) Preparation of Optical Laminate An optical laminate was prepared as follows using the adhesive sheet obtained in (3) above and the uneven-shaped film A in (4) above.

[0150] In the adhesive sheet obtained in (3) above, i.e., a laminate having a laminated structure of first separator / adhesive layer / second separator, one main surface of the adhesive layer is bonded to the release-treated surface of the first separator, and the other main surface of the adhesive layer is bonded to the release-treated surface of the second separator. First, the first separator was peeled from the adhesive sheet obtained in (3) above, and the exposed surface (one main surface) of the adhesive layer was bonded to an acrylic resin film (thickness: 30 μm) between nip rollers including a drive roll and a driven roll, thereby obtaining a laminate having a laminated structure of acrylic resin film / adhesive layer / second separator. Subsequently, the second separator was peeled off from the obtained laminate, and the exposed surface of the adhesive layer (the other main surface) was bonded to the surface having the uneven structure of the unevenly shaped film A (4) between nip rollers including a drive roll and a driven roll to obtain an optical laminate having a laminate structure of acrylic resin film / adhesive layer / unevenly shaped film A. In bonding the laminate of the adhesive layer and acrylic resin film with the unevenly shaped film A, the nip pressure between the nip rollers including the drive roll and the driven roll was as shown in Tables 1A to 1C. As a result, a long optical laminate having a width of 300 mm and a laminate structure of acrylic resin film / adhesive layer / unevenly shaped film A was obtained.

[0151] In the optical laminate, the main surface of the adhesive layer that had been bonded to the release-treated surface of the second separator is bonded to the surface having the concavo-convex structure of the concavo-convex shaped film A. The release-treated surface of T302 used as the second separator had an arithmetic mean roughness Ra of 0.02 μm and a maximum height Rz of 0.15 μm.

[0152] Example 2 An optical laminate was produced in the same manner as in Example 1, except that the thickness of the adhesive layer was changed as shown in Tables 1A to 1C.

[0153] [Example 3] An optical laminate was produced in the same manner as in Example 2, except that the nip pressure between the nip rollers and the type of second separator were changed as shown in Tables 1A to 1C. In Example 3, a commercially available 38 μm thick ultra-high retardation polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, trade name: Diafoil MRF38CK) (hereinafter sometimes referred to as "38CK") was used as the second separator (PET film), that is, the separator to be bonded to the main surface of the adhesive layer that will be bonded to the textured film A. The arithmetic mean roughness Ra of the release-treated surface (surface in contact with the adhesive layer) of 38CK used as the second separator was 0.01 μm, and the maximum height Rz was 0.10 μm.

[0154] Example 4 An optical laminate was produced in the same manner as in Example 3, except that the uneven-shaped film B was used instead of the uneven-shaped film A.

[0155] The unevenly shaped film B had a recessed area ratio Rr of 66% when viewed from the uneven surface side. The unevenly shaped film B had a higher recessed area ratio than the unevenly shaped film A. A plan view of a portion of the used unevenly shaped film B viewed from the uneven surface side is shown in FIG. 14A as an unevenly shaped film 52. FIG. 14B shows a cross-sectional view along 14B-14B' in FIG. 14A. When the unevenly shaped film 52 is viewed from the uneven surface side, the proportion of the area of ​​the recesses 54 to the entire area of ​​the unevenly shaped film 52 was 66%. The recesses 54 of the unevenly shaped film 52 are continuous in the X direction (grooves extending in the X direction) and are arranged at predetermined intervals in the Y direction. The cross-sectional shape of the recesses 54 is a triangle with a depth H of 6.78 μm, a maximum width of 6.5 μm, an inclination angle θa of 50 °, and an inclination angle θb of 85 °. The width of the recesses 54 varies at a period of 17 μm. When the unevenness-forming film 52 is used in a lighting device, for example, the recesses 54 are arranged so as to be convex toward the light source in a plan view.

[0156] Example 5 An optical laminate was produced in the same manner as in Example 4, except that the thickness of the adhesive layer was changed as shown in Tables 1A to 1C.

[0157] Example 6 An optical laminate was produced in the same manner as in Example 2, except that the following adhesive layer was used: The adhesive layer was produced as follows.

[0158] (1) Preparation of Acrylic Polymer Solution First, an acrylic polymer was prepared. In a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 74.6 parts by mass of n-butyl acrylate (BA), 18.6 parts by mass of 4-acryloylmorpholine (ACMO), 6.5 parts by mass of acrylic acid (AA), 0.3 parts by mass of 4-hydroxybutyl acrylate (4HBA), and 0.1 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator were charged together with ethyl acetate so that the total monomer content was 50% by mass. Nitrogen gas was introduced while gently stirring, and the mixture was purged with nitrogen for 1 hour. The liquid temperature in the flask was then maintained at around 58°C, and a polymerization reaction was carried out for 8 hours to obtain an acrylic polymer. Here, after 2 hours had elapsed from the start of the polymerization reaction, ethyl acetate was added dropwise over 3 hours so that the solids content was 35% by mass. That is, the acrylic polymer was obtained as an acrylic polymer solution having a solids content of 35% by mass.

[0159] (2) Preparation of Adhesive Composition Solution Subsequently, 10 parts by mass (solids) of ultraviolet-curable urethane acrylate resin A (mass average molecular weight Mw: 5,500), 1.0 part by mass of 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone (trade name "Omnirad2959", manufactured by IGM Japan LLC) as a photopolymerization initiator, and 0.6 parts by mass of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (trade name "TETRAD-C", manufactured by Mitsubishi Gas Chemical Co., Inc.) as a crosslinking agent were blended into the obtained acrylic polymer solution, relative to 100 parts by mass of the polymer, to prepare an adhesive composition solution (sometimes referred to as "acrylic adhesive composition solution A").

[0160] (3) Preparation of Adhesive Sheet Acrylic adhesive composition solution A was applied to one side of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRF38" manufactured by Mitsubishi Chemical Corporation) that had been treated with a silicone release agent to form an adhesive composition solution layer. The thickness of the adhesive composition solution layer was adjusted to 5 μm after drying (i.e., the thickness of the adhesive composition layer). The adhesive composition solution layer was dried at 150°C for 3 minutes to remove the solvent from the adhesive composition solution layer and crosslink the acrylic polymer with the crosslinking agent, resulting in an adhesive layer having a crosslinked structure formed by the acrylic polymer and the crosslinking agent. Here, the adhesive layer was obtained without curing the UV-curable resin in the adhesive composition solution. The resulting adhesive layer did not have a crosslinked structure formed by curing the UV-curable resin. Next, the adhesive composition layer was bonded to the release-treated surface of a 38 μm thick polyethylene terephthalate (PET) film (product name "MRE38", manufactured by Mitsubishi Chemical Corporation) that had been treated with a silicone release agent, to produce an adhesive sheet having a laminated structure of PET film / adhesive layer / PET film.

[0161] An optical laminate was produced in the same manner as in Example 2 using the adhesive sheet obtained in (3) above.

[0162] Example 7 An optical laminate was produced in the same manner as in Example 6, except that the thickness of the adhesive layer was changed as shown in Tables 1A to 1C.

[0163] Example 8 An optical laminate was produced in the same manner as in Example 7, except that the nip pressure between the nip rollers was changed as shown in Tables 1A to 1C.

[0164] Example 9 An optical laminate was produced in the same manner as in Example 6, except that the nip pressure between the nip rollers was changed as shown in Tables 1A to 1C.

[0165] Example 10 An optical laminate was produced in the same manner as in Example 9, except that the thickness of the adhesive layer was changed as shown in Tables 1A to 1C.

[0166] Example 11 An optical laminate was produced in the same manner as in Example 9, except that the unevenness-imparting film B was used instead of the unevenness-imparting film A.

[0167] Example 12 An optical laminate was produced in the same manner as in Example 11, except that the thickness of the adhesive layer was changed as shown in Tables 1A to 1C.

[0168] [Example 13] (1) Preparation of Acrylic Polymer Solution First, an acrylic polymer was prepared. In a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 90.7 parts by mass of n-butyl acrylate (BA), 6.3 parts by mass of 4-acryloylmorpholine (ACMO), 2.7 parts by mass of acrylic acid (AA), 0.3 parts by mass of 4-hydroxybutyl acrylate (4HBA), and 0.1 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator were charged into the flask together with ethyl acetate so that the total monomer content was 50% by mass. Nitrogen gas was introduced while gently stirring, and the mixture was purged with nitrogen for 1 hour. The liquid temperature in the flask was then maintained at around 58°C, and a polymerization reaction was carried out for 8 hours to obtain an acrylic polymer. Here, after 2 hours had elapsed from the start of the polymerization reaction, ethyl acetate was added dropwise over 3 hours so that the solids content was 35% by mass. That is, the acrylic polymer was obtained as an acrylic polymer solution having a solids content of 35% by mass.

[0169] (2) Preparation of Adhesive Composition Solution An adhesive composition solution (sometimes referred to as "acrylic adhesive composition solution B") was prepared by blending 0.1 parts by mass of 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (trade name "TETRAD-C", manufactured by Mitsubishi Gas Chemical Company, Inc.) as a crosslinking agent with the obtained acrylic polymer solution per 100 parts by mass of the solid content (polymer).

[0170] (3) Preparation of Adhesive Sheet The acrylic adhesive composition solution B was applied to one side of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRF38", manufactured by Mitsubishi Chemical Corporation) that had been treated with a silicone release agent to form an adhesive composition solution layer. The thickness of the adhesive composition solution layer was applied so that the thickness after drying (i.e., the thickness of the adhesive composition layer) would be 5 μm. The adhesive composition solution layer was dried at 150°C for 3 minutes to remove the solvent from the adhesive composition solution layer and crosslink the acrylic polymer with the crosslinking agent, resulting in an adhesive layer having a crosslinked structure formed by the acrylic polymer and the crosslinking agent. The adhesive composition layer was then bonded to the release-treated surface of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRE38", manufactured by Mitsubishi Chemical Corporation) that had been treated with a silicone release agent to prepare an adhesive sheet having a laminated structure of PET film / adhesive layer / PET film.

[0171] (4) Production of Textured Film A The same procedure as in Example 1 was carried out.

[0172] (5) Preparation of optical laminate Using the adhesive sheet obtained in (3) above and the uneven shaped film A in (4), an optical laminate was prepared in the same manner as in Example 1, except that the nip pressure between the nip rollers was changed as shown in Tables 1A to 1C.

[0173] Example 14 (1) Preparation of acrylic polymer solution The same procedure as in Example 13 was carried out.

[0174] (2) Preparation of Adhesive Composition Solution An adhesive composition solution (sometimes referred to as "acrylic adhesive composition solution C") was prepared by blending, relative to 100 parts by mass of the solids content, the obtained acrylic polymer solution with 0.25 parts by mass of dibenzoyl peroxide (1-minute half-life: 130°C) as a crosslinking agent, 0.15 parts by mass of a polyisocyanate crosslinking agent consisting of a trimethylolpropane adduct of tolylene diisocyanate (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), and 0.075 parts by mass of a silane coupling agent (3-glycidoxypropyltrimethoxysilane; product name "KBM-403" manufactured by Shin-Etsu Chemical Co., Ltd.).

[0175] (3) Preparation of Adhesive Sheet The same procedure as in Example 13 was carried out using the acrylic adhesive composition solution C obtained in (2) above, except that the thickness of the adhesive layer was changed as shown in Tables 1A to 1C.

[0176] (4) Production of textured film A The same procedure as in Example 13 was carried out.

[0177] (5) Preparation of Optical Laminate The same procedure as in Example 13 was carried out.

[0178] Example 18 An optical laminate was produced in the same manner as in Example 14, except that the thickness of the adhesive layer was changed as shown in Tables 1A to 1C.

[0179] Example 15 An optical laminate was produced in the same manner as in Example 14, except that the nip pressure between the nip rollers was changed as shown in Tables 1A to 1C.

[0180] Example 16 An optical laminate was produced in the same manner as in Example 15, except that the thickness of the adhesive layer was changed as shown in Tables 1A to 1C.

[0181] [Example 17] An optical laminate was prepared in the same manner as in Example 13, except that the thickness of the adhesive layer and the nip pressure between the nip rollers were changed as shown in Tables 1A to 1C, and the unevenly shaped film B was used instead of the unevenly shaped film A.

[0182] Comparative Example 2 (1) Preparation of acrylic polymer solution The same procedure as in Example 13 was carried out.

[0183] (2) Preparation of Adhesive Composition Solution To the obtained acrylic polymer solution, 0.15 parts by mass of a trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, product name: Coronate L) as a crosslinking agent and 0.075 parts by mass of dibenzoyl peroxide (manufactured by NOF Corporation: Niper BMT40 (SV)) were blended relative to 100 parts by mass of the polymer to prepare an adhesive composition solution (sometimes referred to as "acrylic adhesive composition solution D"). An optical laminate was produced in the same manner as in Example 13, except that the nip pressure between the nip rollers was changed as shown in Tables 1A to 1C.

[0184] [Measurement Method] The measurement conditions for each characteristic are as follows.

[0185] <Air bubble area ratio> The optical laminates produced in the examples and comparative examples were cut into 10 cm squares, and five locations within each were observed under a microscope. The observation method was to capture an image of a 3.5 mm × 3.5 mm viewing angle range using an optical microscope, and binarize the image to identify air bubble areas and non-air bubble areas, thereby calculating the air bubble area ratio (air bubble area ratio = air bubble area / total viewing area). The smallest air bubble size detectable by the optical microscope was 1.7 μm (one pixel size (pixel resolution) is a square of 1.7 μm × 1.7 μm).

[0186] <Height of adhesive layer present in the recess of the concave-convex film> The cross section of the produced optical laminate was cut out, and for any one recess, the height of the adhesive layer present in the recess was measured using SEM. Specifically, first, a 5 mm square size was cut out from the optical laminate produced in each example and comparative example. Then, the cut-out test piece was cooled, and a cross section was prepared by FIB processing (Helios G4 UX Dual Beam System manufactured by FEI), and a cross-sectional SEM image was observed.

[0187] <Surface Roughness Ra, Rz of Adhesive Layer> One side of the separator (PET film) was peeled off from the adhesive sheet obtained in each of the Examples and Comparative Examples, and the surface roughness of the exposed adhesive layer was measured using a non-contact shape measuring instrument (NewView7300, manufactured by ZYGO). The measurement method followed the method described in JIS B0601-2001, and the arithmetic mean roughness Ra and maximum height Rz of the adhesive layer surface were measured. In Tables 1A to 1C, "-" indicates that no measurement was performed.

[0188] <Nip Pressure (Laminating Pressure), Pressure Applied to Flat Section> To measure the nip pressure (laminating pressure) between rolls, pressure-sensitive paper (Prescale 3LW, manufactured by Fujifilm Corporation) was attached to the entire nipped width of the roll (width 250 mm, diameter 200 mm), and the pressure (MPa) was measured. Tables 1A to 1C list the average value across the entire nipped width as "nip pressure (laminating pressure) Pl." Note that with the rolls used here, the pressure unevenness in the TD direction shown schematically in Figure 6 did not substantially occur. The pressure unevenness in the TD direction shown schematically in Figure 6 tends to occur more easily when the ratio of the roll width (length in the TD direction) to the roll diameter is large.

[0189] The pressure Pf applied to the flat portion (i.e., the pressure applied to the portion other than the recessed portion) was calculated by subtracting the area of ​​the recessed portion from the value of the nip pressure between the rolls measured as described above, assuming that no pressure is applied to the recessed portion on the surface of the unevenly shaped film, as shown in the following formula. The recessed portion occupation area ratio Rr used the design value of the unevenly shaped film. (Pressure applied to the flat portion Pf) = (Nip pressure Pl) / (1 - recessed portion occupation area ratio Rr)

[0190] <Compressive Stress-Strain Curve of Adhesive Layer> Figure 18 is a schematic perspective view illustrating a method for measuring the compressive stress-strain curve of the adhesive layer. Each adhesive layer 20a (20 μm thick) of the examples was cut into a size of approximately 10 mm x 10 mm (10 mm square), placed on an acrylic film 41, and subjected to Pt-Pd vapor deposition for 30 seconds. The layer was then fixed to a predetermined support and nanoindentation measurement was performed to obtain a compressive stress-strain curve. The measurement results were output, for example, as load (N) per displacement (mm). The load was divided by the area of ​​the indenter to obtain stress, and the displacement was divided by the thickness of the adhesive layer to obtain strain, thereby obtaining a compressive stress-strain curve. Using the obtained data, a compressive stress (y)-strain curve (x) was calculated using the equation y = a x x ｂ The fitting was performed using the following approximate formula. (Analysis device and measurement conditions) Device: Triboldenter manufactured by Hysitron Inc. Indenter used: Flat (cylinder radius ra = 97.87 μm) Measurement method: Single indentation measurement Indentation depth setting: 2 μm Measurement temperature: Room temperature

[0191] <180° Peel Adhesion Strength of Adhesive Layer to Optical Sheet> Figures 19A, 19B, and 19C are schematic cross-sectional views, top views, and cross-sectional views for explaining a method for measuring the 180° peel adhesive strength of the adhesive layer to the optical sheet.

[0192] As shown in FIG. 19A, an acrylic plate 42 (thickness 3 mm) was placed on top of an acrylic adhesive layer 49A (thickness 100 μm), followed by an unevenness-imparting film 70 (unevenness-imparting film A) (thickness 130 μm) and an adhesive layer 20a (thickness 15 μm) of each example. A 25 mm wide film laminate 40f having a laminated structure of an acrylic film 43 (thickness 20 μm) / an acrylic adhesive layer 49B (thickness 100 μm) / a PET film 44 (thickness 75 μm) was attached to the adhesive layer 20a, and a 180 ° peel test was performed. A PET film (thickness 38 μm) was inserted between the adhesive layer 20a and the unevenness-imparting film 70 (arrow in FIG. 19A), so that peeling occurred at the interface between the adhesive layer 20a and the unevenness-imparting film 70. The concave-convex film 70 was positioned so that the inclined surface of the recess 74 having an inclination angle θa (49°) was farther from the folded position of the film laminate 40f than the inclined surface having an inclination angle θb (85°). The acrylic adhesive layers 49A and 49B are known general-purpose adhesives. (Apparatus and measurement conditions) Apparatus: Autograph AGT-5N (manufactured by Shimadzu Corporation) Peeling speed: 150 mm / min Measurement temperature: Room temperature

[0193] For Examples using adhesive layers formed from acrylic adhesive composition solution A, B, or C, measurements were taken at 1,640 equally spaced points within a range of 20 mm to 40 mm from the edge (the starting point of peeling), and the 180° peel adhesive strength (N / 25 mm) was calculated by averaging the measurements. For Examples using adhesive layers formed from polyester adhesive composition solution A, measurements were taken at 2,440 equally spaced points within a range of 10 mm to 40 mm from the edge, and the 180° peel adhesive strength (N / 25 mm) was calculated by averaging the measurements. The stress Sp (MPa) was calculated by dividing the obtained 180° peel adhesive strength (N / 25 mm) by the cross-sectional area of ​​the film (i.e., the cross-sectional area of ​​the film laminate 40f, 25 mm × 195 μm).

[0194] <Calculated embedment amount Dd> The calculated embedment amount Dd of the adhesive layer in each example was calculated. Tables 1A to 1C show the calculated embedment amount Dd calculated by two methods. The calculated embedment amount Dd (1) is calculated using the approximate equation y = a × x of the compressive stress (y) - strain (x) curve of the adhesive layer 20a. ｂ The calculated embedding amount Dd(2) is calculated by the approximate equation y = a × x of the compressive stress (y) - strain (x) curve of the adhesive layer 20a. ｂ The embedded amount dmax shown in Tables 1A to 1C was calculated by multiplying the strain in response to the pressure Pf applied to the flat portion of the adhesive layer 20a in the compressive stress-strain curve by the thickness Dt of the adhesive layer 20a. The embedded amount dmax was also calculated using two methods. The embedded amount dmax (1) was calculated using the approximate equation y=a×x for the compressive stress (y)-strain (x) curve of the adhesive layer 20a. ｂ The closest value is selected from the compressive stress measurement results without using the formula, and dmax(2) is the approximate formula y=a×x for the compressive stress (y)-strain (x) curve of the adhesive layer 20a. ｂ The calculated embedding amount Dd(1) was calculated using dmax(1), and the calculated embedding amount Dd(2) was calculated using dmax(2).

[0195] The evaluation results are shown in Tables 1A, 1B, 1C, FIGS. 10, and 17. A "-" in Tables 1A to 1C indicates that no measurement or calculation was performed. FIG. 10 is a graph showing the evaluation results of the area ratio (%) of bubbles and the height (μm) of the adhesive layer present in the recesses in the optical laminates of Examples 1 to 18. In FIG. 10, the results of Examples 1 to 5 using polyester adhesive composition solution A are shown as hatched circles or triangles, the results of Examples 6 to 12 using acrylic adhesive composition solution A are shown as black circles or triangles, and the results of Examples 13 to 18 using acrylic adhesive composition solution B or C are shown as white circles or triangles. The results of the unevenly shaped film A are shown as circles, and the results of the unevenly shaped film B are shown as triangles. Note that the results of Comparative Example 2 are not shown in FIGS. 10 and 17. 17 is a graph showing the correlation between the measured height (μm) of the adhesive layer present in the recesses and the calculated embedding amount Dd(1) (μm) for the optical laminates of Examples 1 to 18. The results for Examples 1 to 18 are shown with the same symbols as in FIG.

[0196] The 180 ° peel adhesive strength of the adhesive layer to the optical sheet was measured only using the unevenly shaped film A, and not using the unevenly shaped film B. In Tables 1A to 1C, the "180 ° peel adhesive strength" and "stress Sp obtained from the peel adhesive strength" for the examples (Examples 4, 5, 11, 12 and 17) using the unevenly shaped film B describe the measurement results of the 180 ° peel adhesive strength for the unevenly shaped film A using the same adhesive layer and the stress Sp value obtained therefrom. For the examples using the unevenly shaped film B, the calculations of "Sp × sin θa", the embedded amount dmax and the calculated embedded amount Dd in Tables 1A to 1C were performed using those values. The "stress F2 calculated from the peel adhesive strength of the adhesive layer 20a to the first optical sheet 10a" described with reference to Figure 16A is, strictly speaking, the stress calculated from the peel adhesive strength of the adhesive layer 20a to the inclined surfaces of the recesses 14 having an inclination angle θa. However, because it is difficult to actually measure the peel adhesive strength of the adhesive layer 20a to the inclined surfaces of the recesses 14, the inventors have devised a method for measuring the 180° peel adhesive strength of the adhesive layer 20a to a surface that is as flat as possible and made of the same material as the inclined surfaces of the recesses 14, and then using the results to calculate the calculated embedment amount Dd regardless of the density of the recesses in the optical sheet (texture-imparting film) to be bonded to the adhesive layer 20a. The lower the density of the recesses 14 on the first main surface 12s of the first optical sheet 10a, the greater the proportion of flat portions 10s, which is considered to be closer to a flat surface and more suitable for measuring the 180° peel adhesive strength. With this in mind, the 180° peel adhesive strength of the adhesive layer 20a to the first main surface 12s (flat portion 10s) of the first optical sheet 10a was measured using the textured film A, which has a low density of recesses.

[0197]

[0198]

[0199]

[0200] In the optical laminates of Examples 1 to 17, the area ratio of bubbles present at the interface between the flat portion and the adhesive layer is 3% or less, and the height of the adhesive layer present in multiple recesses is 2 μm or less. In contrast, in the optical laminates of Example 18 and Comparative Example 2, the area ratio of bubbles present at the interface between the flat portion and the adhesive layer is greater than 3%, and / or the height of the adhesive layer present in multiple recesses is greater than 2 μm. The optical laminates of Examples 14 and 18 were produced with only the thickness Dt of the adhesive layer on the flat portion different. However, the area ratio of bubbles present at the interface between the flat portion and the adhesive layer is suppressed to 3% or less in the optical laminate of Example 14, while it exceeds 3% in the optical laminate of Example 18. From these results, it is preferable that the thickness Dt of the adhesive layer on the flat portion is, for example, 2 μm or more. The thickness Dt of the adhesive layer may be, for example, 3 μm or more. The upper limit of the thickness Dt of the adhesive layer is not particularly limited and is, for example, 10 μm or less. However, the area ratio of air bubbles present at the interface between the flat portion and the adhesive layer can vary depending not only on the thickness of the adhesive layer on the flat portion but also on the pressure applied to the adhesive layer and the optical sheet when bonding them together, the surface roughness of the separator used to prepare the adhesive layer (specifically, the surface roughness of the separator to be bonded to the surface of the adhesive layer that is bonded to the surface of the optical sheet having the concave-convex structure), the gel fraction of the adhesive layer, etc. The degree of penetration of the adhesive layer into the multiple recesses of the concave-convex structure (the height of the adhesive layer present in the recesses) can also vary depending on the preparation conditions and physical properties of the adhesive layer. For example, even if the same adhesive composition solution is used, if the thickness of the adhesive layer (thickness of the adhesive layer on the flat portion) is different, the crosslink density of the adhesive layer may differ, and therefore the degree of penetration of the adhesive layer into the multiple recesses may differ. Therefore, without being limited to the above-described examples, optical laminates according to embodiments of the present invention can be obtained by appropriately adjusting the preparation conditions and physical properties of the adhesive layer.

[0201] In Examples 6 to 12, in which acrylic adhesive composition solution A was used, the adhesive layer was prepared without curing the UV-curable resin contained in acrylic adhesive composition solution A, as described above. This is not a limitation, and the adhesive layer may contain a cured product of a UV-curable resin. That is, an adhesive layer may be used in which the UV-curable resin is cured using an acrylic adhesive composition solution containing a UV-curable resin. Whether or not the UV-curable resin is cured does not significantly change the surface roughness of the resulting adhesive layer, and the area ratio of bubbles in the optical laminate does not significantly change either.

[0202] 17 , a comparison of the calculated embedding amount Dd with the measured height of the adhesive layer 20a present in the recess 14 confirmed a certain correlation. The calculated embedding amount Dd can be used to represent an optical laminate in which the adhesive layer 20a is prevented from penetrating into the recess 14. Specifically, when the height (measured value) of the adhesive layer present in the recess 14 is 2 μm or less, it can be said that the calculated embedding amount Dd is 1.3 μm or less.

[0203] As shown in Tables 1A to 1C, in all of the Examples, i.e., when using acrylic adhesive composition solutions A, B, and C, and polyester adhesive composition solution A, the calculated embedment amount Dd is 1.3 μm or less. It can also be seen that the calculated embedment amount Dd is 1.3 μm or less using either calculation method (1) or (2) (i.e., when using or not using an approximation equation for the compressive stress-strain curve of the adhesive layer), and that Dd is 0.5 μm or less. The lamination pressure Pl is 0.1 MPa or more. There are no limitations on the upper limit of the lamination pressure Pl, but it is, for example, 0.5 MPa or less.

[0204] As shown in Tables 1A to 1C, the compressive stress (y)-strain (x) curve of the adhesive layer formed from the polyester adhesive composition solution A is expressed by the approximate formula y=278x ２．１９ The compressive stress (y)-strain (x) curve of the adhesive layer formed from the acrylic adhesive composition solution A is expressed by the approximate formula y=212x ２．２４The compressive stress (y)-strain (x) curve of the adhesive layer formed from the acrylic adhesive composition solutions B and C is expressed by the approximate formula y=28x ２．１０ The acrylic adhesive composition solutions B and C differ only in the type of crosslinking agent. The difference in the crosslinking agent did not affect the compressive stress-strain curve of the adhesive layer formed. The approximate equation for the compressive stress (y)-strain (x) curve of the adhesive layer is y=ax ｂ When comparing the adhesive layers, there is a particularly large difference in coefficient a, and it can be said that the larger the coefficient a, the larger the compressive modulus (harder). Among the adhesive layers used in the examples, the adhesive layer formed from polyester adhesive composition solution A has the largest coefficient a, followed by the adhesive layer formed from acrylic adhesive composition solution A, and the adhesive layers formed from acrylic adhesive composition solutions B and C, in that order.

[0205] In the examples using acrylic adhesive composition solution A, B, or C (excluding Examples 8, 11, and 12), the stress F2 due to peel adhesive strength was equal to or greater than the restoring force F1 due to compressive elasticity (F2≧F1), i.e., Sp×sin θa≧Pf was satisfied, and the calculated embedding amount Dd was equal to the embedding amount dmax. The embedding amount dmax is the value obtained by multiplying the strain corresponding to Pf in the compressive stress-strain curve of the adhesive layer by the thickness Dt of the adhesive layer. These examples are considered to correspond to the case described with reference to FIG. 8B.

[0206] In contrast, in the examples using polyester adhesive composition solution A and examples 8, 11, and 12 using acrylic adhesive composition solution A, the stress F2 caused by the peel adhesive strength is smaller than the restoring force F1 due to compressive elasticity (F2<F1), i.e., Sp×sin θa<Pf is satisfied, and the calculated embedding amount Dd is the value obtained by multiplying the strain corresponding to Sp×sin θa in the compressive stress-strain curve of the adhesive layer by the thickness Dt of the adhesive layer. These examples are considered to fall into the case described with reference to FIG. 8A .

[0207] From the viewpoint of the magnitude of the compressive elastic modulus, the approximate formula y = ax ｂIn the approximation formula, a is preferably 150 or more, and more preferably 250 or more. ｂ The value of b is not particularly limited, but may be, for example, equal to or greater than 2. The stress Sp calculated from the peel adhesive strength is, for example, equal to or less than 0.5 MPa.

[0208] Depending on the application of the adhesive layer and the optical laminate, the adhesive layer may have any compressive elastic modulus. For example, the approximation formula y=ax ｂ The value of a in the formula (1) may be, for example, 30 or less. The stress Sp calculated from the peel adhesive strength is, for example, 1.0 MPa or more.

[0209] The adhesive layer formed from polyester-based adhesive composition solution A is an example of the adhesive layer Ac described in the aforementioned International Application PCT / JP2022 / 004554 by the applicant; that is, it is formed by crosslinking an adhesive composition containing a polyester resin that is a copolymer of a polycarboxylic acid and a polyhydric alcohol, a crosslinking agent, and at least one crosslinking catalyst selected from the group consisting of organic zirconium compounds, organic iron compounds, and organic aluminum compounds, and has a gel fraction of 40% or more after being held at a temperature of 85°C and a relative humidity of 85% for 300 hours, and a 180° peel adhesive strength to a PMMA film of 100 mN / 20 mm or more.

[0210] The adhesive layer formed from the acrylic adhesive composition solution A is an example of the adhesive layer Aa described in the above-mentioned WO 2021 / 167090 by the present applicant, that is, in a creep test using a rotational rheometer, the creep deformation rate when a stress of 10,000 Pa is applied for 1 second at 50°C is 10% or less, and the creep deformation rate when a stress of 10,000 Pa is applied for 30 minutes at 50°C is 16% or less, and the 180° peel adhesive strength to a PMMA film is 10 mN / 20 mm or more.

[0211] <Changes in the degree of penetration of the adhesive layer into recesses during and after lamination> Using the optical laminates of Examples A and B below, changes in the degree of penetration of the adhesive layer into recesses during and after lamination were observed.

[0212] The optical laminate of Example A was prepared in the same manner as the optical laminate of Example 1, except that the thickness of the adhesive layer was 300 μm, and the optical laminate had a laminate structure of acrylic resin film / adhesive layer / concave-convex shaped film B. The optical laminate of Example B was prepared in the same manner as Example 18, except that the thickness of the adhesive layer was 160 μm, and the optical laminate had a laminate structure of acrylic resin film / adhesive layer / concave-convex shaped film B. Here, the adhesive layer was made thick so that the penetration (embedding) of the adhesive layer into the recesses could be easily observed.

[0213] As shown in FIG. 11A, a transparent plate 150A was placed on one main surface of the optical laminate 100S of Example A, and a transparent plate 150B was placed on the other main surface to form a sample 1000A. FIG. 11B is a schematic diagram showing a cross section of the sample 1000A. The transparent plate 150B is shorter than the optical laminate 100S, so that the optical laminate 100S of Example A abuts against the corner of the transparent plate 150B. The optical laminate 100S of Example A was pressed against the corner of the transparent plate 150B, and a force was applied to the optical laminate 100S of Example A by hand via the transparent plate 150A (arrow in the figure). The optical laminate 100S (dashed ellipse in the figure) was observed while the force was being applied and after the force was removed.

[0214] Fig. 12 shows optical images of Sample 1000A (top row) before force is applied, Sample 1000A (middle row) while force is being applied, and Sample 1000A (bottom row) after force is removed. Fig. 13 shows the results of a similar evaluation using the optical laminate of Example B instead of the optical laminate of Example A. Fig. 13 shows optical images of a sample having the optical laminate of Example B (top row) before force is applied, a sample having the optical laminate of Example B (middle row) while force is being applied, and a sample having the optical laminate of Example B (bottom row) after force is removed.

[0215] As can be seen from Figures 12 and 13, in both the optical laminate of Example A and the optical laminate of Example B, when force is applied (middle of Figures 12 and 13), there are areas where the transparency is improved compared to before the force is applied (upper of Figures 12 and 13) (dashed ellipse in the figure). This is because before the force is applied, multiple internal spaces are formed by the uneven surface of the unevenly shaped film and the adhesive layer, whereas when force is applied, the recesses of the unevenly shaped film are filled with the adhesive layer, and the multiple internal spaces constituting the light distribution control structure disappear. When the applied force is removed (lower of Figures 12 and 13), the transparency of the optical laminate of Example A returns to its original state, while the transparency of the optical laminate of Example B remains improved and does not return to its original state. When the optical laminate is observed with an optical microscope, no pattern of multiple internal spaces is observed in the areas where the transparency is improved, confirming that no internal spaces are formed. That is, in the optical laminate of Example A, the adhesive layer that had penetrated into the recesses due to the application of force returned to a state in which it did not penetrate into the recesses (or a state in which penetration into the recesses was suppressed) when the force was removed, whereas in the optical laminate of Example B, the adhesive layer that had penetrated into the recesses due to the application of force appears to have remained in the recesses even after the force was removed. However, since the adhesive layer was made thick and evaluated here so that the penetration (embedding) of the adhesive layer into the recesses could be easily observed, this evaluation result does not limit the adhesive layer possessed by the optical laminate of the present invention. As described above, in the optical laminates of Examples 14 to 16, which used adhesive layers with the same composition as the optical laminate of Example B, the area ratio of bubbles present at the interface between the flat portion and the adhesive layer was 3% or less, and the height of the adhesive layer present in multiple recesses was 2 μm or less.

[0216] The optical laminate of the present invention is widely used in optical devices such as display devices and lighting devices.

[0217] 10a First optical sheet 12s, 18s Main surface (surface) 20a Adhesive layer 60 Light source 80 Light guide layer 100A, 102A, 102B Optical laminate 200A, 200B Illumination device

Claims

1. Step A of preparing a first optical sheet having a first major surface with a concavo-convex structure and a second major surface opposite to the first major surface, wherein the concavo-convex structure includes a plurality of concave portions and flat portions between adjacent concave portions among the plurality of concave portions; Step B of preparing an adhesive layer; Step C of bonding the adhesive layer to the first major surface of the first optical sheet which includes each of the plurality of concave portions has an inclined surface with an inclination angle θa, the stress obtained by dividing the 180° peel adhesive force of the adhesive layer with respect to the first major surface of the first optical sheet, obtained by a 180° peel test, by the film cross-sectional area is Sp, in Step C, the pressure when bonding the adhesive layer to the first major surface of the first optical sheet is Pl, in Step C, the pressure applied to the flat portion when bonding the adhesive layer to the first major surface of the first optical sheet is Pf, when Sp × sin θa ≥ Pf, the value obtained by multiplying the thickness Dt of the adhesive layer by the strain corresponding to Pf in the compression stress-strain curve of the adhesive layer is Dd, when Sp × sin θa < Pf, when the value obtained by multiplying the thickness Dt of the adhesive layer by the strain corresponding to Sp × sin θa in the compression stress-strain curve of the adhesive layer is Dd, A method for manufacturing an optical laminate, wherein Dd is 1.3 μm or less.

2. The manufacturing method according to claim 1, wherein Dd is 0.5 μm or less.

3. The manufacturing method according to claim 1 or 2, wherein the pressure Pl in Step C is 0.1 MPa or more and 0.5 MPa or less.

4. The manufacturing method according to claim 1 or 2, wherein the thickness Dt of the adhesive layer is 3 μm or more and 10 μm or less.

5. The compression stress (y)-strain (x) curve of the adhesive layer is approximated by y = a × x ｂ and the manufacturing method according to claim 1 or 2, wherein a is 150 or more and b is 2 or more.

6. The compression stress (y)-strain (x) curve of the adhesive layer is approximated by y = a × x ｂ and the manufacturing method according to claim 5, wherein a is 250 or more.

7. The compression stress (y)-strain (x) curve of the adhesive layer is approximated by y = a × x ｂ and the manufacturing method according to claim 1 or 2, wherein a is 30 or less and b is 2 or more.

8. The manufacturing method according to claim 1 or 2, satisfying Sp × sin θa < Pf.

9. The manufacturing method according to claim 1 or 2, wherein the stress Sp is 0.5 MPa or less.

10. The manufacturing method according to claim 1 or 2, wherein the stress Sp is 1.0 MPa or more.

11. The adhesive layer is formed by crosslinking an adhesive composition containing a polyester resin which is a copolymer of a polyvalent carboxylic acid and a polyvalent alcohol, a crosslinking agent, and at least one crosslinking catalyst selected from the group consisting of an organic zirconium compound, an organic iron compound, and an organic aluminum compound, has a gel fraction of 40% or more after being held at a temperature of 85° C. and a relative humidity of 85% for 300 hours, and the manufacturing method according to claim 1 or 2, wherein the 180° peel adhesive strength to a PMMA film is 100 mN / 20 mm or more.

12. The adhesive layer is the following adhesive layer Aa or adhesive layer Ab, and the manufacturing method according to claim 1 or 2: In a creep test using a rotational rheometer, when a stress of 10,000 Pa is applied at 50 °C for 1 second, the creep deformation rate is 10% or less, and when a stress of 10,000 Pa is applied at 50 °C for 30 minutes, the creep deformation rate is 16% or less. The adhesive layer Aa having a 180° peel adhesion to the PMMA film of 10 mN / 20 mm or more; It is formed by curing the curable resin of the adhesive composition containing a polymer and a curable resin. The initial tensile elastic modulus at 23 °C before curing the curable resin of the adhesive composition is 0.35 MPa or more and 8.00 MPa or less. The adhesive layer Ab having an initial tensile elastic modulus at 23 °C of 1.00 MPa or more after curing the curable resin of the adhesive composition.

13. The manufacturing method according to claim 1 or 2, wherein the inclined surface directs a part of the light propagating in the adhesive layer toward the second main surface side of the first optical sheet by total internal reflection.

14. Each of the plurality of recesses has another inclined surface on the side opposite to the inclined surface. The manufacturing method according to claim 1 or 2, wherein the inclination angle θa of the inclined surface is smaller than the inclination angle θb of the other inclined surface.

15. The step B is Step Ba of applying an adhesive composition solution having a (meth)acrylic polymer and / or a polyester polymer, a crosslinking agent, and a solvent onto the peeled main surface of a substrate having a peeled main surface to form an adhesive composition solution layer; Step Bb of removing the solvent of the adhesive composition solution layer to form an adhesive composition layer; Step Bc of providing another substrate having a peeled main surface on the main surface of the adhesive composition layer opposite to the substrate so that the peeled main surface is in contact with the adhesive composition layer. Step Bd of forming the adhesive layer by crosslinking the (meth)acrylic polymer and / or polyester polymer in the adhesive composition layer with the crosslinking agent and includes Step C includes Step Ca of bonding the first main surface of the first optical sheet and the main surface on one side of the base material or the other base material of the adhesive layer The manufacturing method according to claim 1 or 2, which includes

16. The manufacturing method according to claim 15, wherein the arithmetic mean roughness Ra of the peeled main surface of the base material or the other base material is less than 0.05 μm.

17. The manufacturing method according to claim 16, wherein the maximum height Rz of the peeled main surface of the base material or the other base material is less than 0.5 μm.

18. The manufacturing method according to claim 15, wherein Step Ca is performed by a roll-to-roll method.

19. When the ratio of the area of the plurality of recesses to the area of the first optical sheet when viewed in plan from the normal direction of the first main surface is Rr, The pressure Pf applied to the flat portion in Step C is obtained by dividing the pressure Pl in Step C by (1 - Rr). The manufacturing method according to claim 1 or 2.

20. A first optical sheet having a first main surface with an uneven structure and a second main surface on the side opposite to the first main surface, wherein the uneven structure includes a plurality of recesses and flat portions between adjacent recesses among the plurality of recesses. A first optical sheet, An adhesive layer disposed on the first main surface side of the first optical sheet and in contact with the flat portion and has An internal space is defined in each of the plurality of recesses between the surface of the adhesive layer and the first main surface of the first optical sheet, Each of the plurality of recesses has an inclined surface with an inclination angle θa, The adhesive layer is attached to the first major surface of the first optical sheet under a pressure Pl, The pressure applied to the flat portion when the adhesive layer is bonded to the first major surface of the first optical sheet is Pf, The stress obtained by dividing the 180° peel adhesion force of the adhesive layer to the first major surface of the first optical sheet, determined by a 180° peel test, by the film cross-sectional area is Sp, When Sp × sin θa ≥ Pf, a value obtained by multiplying the thickness Dt of the adhesive layer by the strain corresponding to Pf in the compression stress-strain curve of the adhesive layer is defined as Dd, When Sp × sin θa < Pf, when a value obtained by multiplying the thickness Dt of the adhesive layer by the strain corresponding to Sp × sin θa in the compression stress-strain curve of the adhesive layer is defined as Dd, An optical laminate in which Dd is 1.3 μm or less.

21. The adhesive layer is, formed by crosslinking an adhesive composition containing a polyester resin that is a copolymer of a polyvalent carboxylic acid and a polyhydric alcohol, a crosslinking agent, and at least one crosslinking catalyst selected from the group consisting of an organic zirconium compound, an organic iron compound, and an organic aluminum compound, the gel fraction is 40% or more after being held at a temperature of 85° C. and a relative humidity of 85% for 300 hours, The optical laminate according to claim 20, wherein the 180° peel adhesion force to a PMMA film is 100 mN / 20 mm or more.

22. The optical laminate according to claim 20, wherein the adhesive layer is the following adhesive layer Aa or adhesive layer Ab: In a creep test using a rotational rheometer, the creep deformation rate when a stress of 10,000 Pa is applied at 50° C. for 1 second is 10% or less, and the creep deformation rate when a stress of 10,000 Pa is applied at 50° C. for 30 minutes is 16% or less, The adhesive layer Aa, wherein the 180° peel adhesion force to a PMMA film is 10 mN / 20 mm or more; It is formed by curing the curable resin of the adhesive composition containing a polymer and a curable resin. The initial tensile elastic modulus at 23 °C before curing the curable resin of the adhesive composition is 0.35 MPa or more and 8.00 MPa or less. The adhesive layer Ab has an initial tensile elastic modulus at 23 °C after curing the curable resin of the adhesive composition of 1.00 MPa or more.