CN116670244A

CN116670244A - Optical laminate and optical device

Info

Publication number: CN116670244A
Application number: CN202280008729.6A
Authority: CN
Inventors: 田中亚树子; 水野瑞穗; 中村恒三; 翁宇峰
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2021-02-19
Filing date: 2022-02-04
Publication date: 2023-08-29

Abstract

The present invention relates to an optical laminate (100B 1) comprising se:Sub>A 1 st optical sheet (10 se:Sub>A) and an adhesive layer (20B) disposed on the 1 st principal surface side of the 1 st optical sheet, wherein the 1 st optical sheet (10 se:Sub>A) comprises se:Sub>A 1 st principal surface (12 s) and se:Sub>A 2 nd principal surface (18 s) on the opposite side of the 1 st principal surface, and the 1 st principal surface (12 s) comprises se:Sub>A concave-convex structure comprising se:Sub>A plurality of concave portions (14) and flat portions (10 s) between adjacent concave portions in the plurality of concave portions, the adhesive layer is in contact with the flat portions, the surface of the adhesive layer and the 1 st principal surface of the 1 st optical sheet define an internal space (14 se:Sub>A) in each concave portion in the plurality of concave portions, and when the maximum value of the height of the adhesive layer present in the concave portion is A, the minimum value of the height of the adhesive layer present in the concave portion is B, and the depth of the concave portion is C, the plurality of concave portions satisfy 0.10 (C-A)/C1.00 and 0.75C-A)/(C-B), respectively.

Description

Optical laminate and optical device

Technical Field

The present invention relates to an optical laminate and an optical device having the same.

Background

Optical sheets (e.g., a micro lens sheet, a prism sheet, a brightness enhancement film (e.g., brightness Enhancement Film: BEF (registered trademark)) manufactured by 3M company) are used for various optical devices (e.g., display devices and lighting devices). In the present specification, the "optical sheet" is not limited to the above-described illustrative examples, but includes a sheet-like optical member widely, and includes, for example, a diffusion plate and a light guide plate. The optical sheet is attached to another optical sheet or an optical device, for example, using an adhesive layer. In the present specification, the term "optical laminate" refers to a structure including an optical sheet and an adhesive layer or a structure including a plurality of optical sheets. In this specification, "adhesive" is used in the sense of including an adhesive (also referred to as "pressure-sensitive adhesive").

The present inventors have disclosed an optical laminate usable in a display device or a lighting device in patent document 1 (referred to as an "optical laminate" in patent document 1). The optical laminate of patent document 1 includes: an optical sheet (for example, a microlens sheet) having a concave-convex structure on the surface thereof, and an adhesive layer provided on the surface thereof, wherein 5 to 90% of the height of the convex portion of the concave-convex structure is embedded in the adhesive layer, and the adhesive layer is formed from an adhesive composition comprising a graft polymer obtained by graft polymerizing a chain comprising a cyclic ether group-containing monomer with a (meth) acrylic polymer and a photo-cationic polymerization initiator or a thermosetting catalyst.

Patent documents 2 and 3 disclose light distribution structures that can be used for display devices and lighting devices, which utilize total reflection at interfaces between a plurality of air cavities. The degree of freedom and accuracy of light distribution control can be improved if the light distribution structures disclosed in patent documents 2 and 3 are used. The disclosures of patent documents 2 and 3 are incorporated by reference in their entirety into the present specification.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2012-007046

Patent document 2: international publication No. 2011/124765

Patent document 3: international publication No. 2019/087118

Disclosure of Invention

Problems to be solved by the invention

When an adhesive layer is attached to the surface of an optical sheet having a concave-convex structure, the degree to which the adhesive layer intrudes into the concave portion of the concave-convex structure (fills the concave portion) affects the function of the optical sheet. Therefore, it is required to suppress the penetration of the adhesive layer into the concave portion of the concave-convex structure (the ratio of the volume of the adhesive layer existing in the space defined by the concave portion of the concave-convex structure to the volume of the space).

The present inventors have studied to form a plurality of air cavities (internal spaces) constituting the light distribution structures (light distribution control structures) described in patent documents 2 and 3 by the surface of the optical sheet having the concave-convex structure and the surface of the adhesive layer adhered to the surface of the optical sheet having the concave-convex structure. Patent documents 2 and 3 do not describe the formation of a plurality of air cavities (internal spaces) constituting a light distribution structure by the surface having the concave-convex structure of the optical sheet and the surface of the adhesive layer, nor do they examine the relationship between the degree of penetration of the adhesive layer into the concave portions of the concave-convex structure and the influence on light distribution control.

The present invention has been made to solve the above-described problems, and an object thereof is to provide an optical laminate having an adhesive layer in which penetration into recesses of an uneven structure of an optical sheet is suppressed, and an optical device having such an optical laminate.

Means for solving the problems

According to an embodiment of the present invention, a solution described in the following items is provided.

[ item 1]

An optical laminate comprising a 1 st optical sheet and an adhesive layer disposed on the 1 st principal surface side of the 1 st optical sheet, wherein the 1 st optical sheet comprises a 1 st principal surface and a 2 nd principal surface on the opposite side of the 1 st principal surface, the 1 st principal surface has a concave-convex structure,

the concave-convex structure includes a plurality of concave portions and a flat portion between adjacent concave portions among the plurality of concave portions,

the adhesive layer is in contact with the flat portion,

the surface of the adhesive layer and the 1 st main surface of the 1 st optical sheet define an internal space in each of the plurality of recesses,

the plurality of concave portions satisfy 0.10.ltoreq.C-A/C.ltoreq.1.00 and 0.75.ltoreq.C-A)/(C-B), respectively, with A being the maximum value of the height of the adhesive layer present in the concave portion, B being the minimum value of the height of the adhesive layer present in the concave portion, and C being the depth of the concave portion.

[ item 2]

The optical laminate according to item 1, wherein,

the adhesive layer on the flat portion has a thickness of 0.01 μm or more and 15.0 μm or less.

[ item 3]

The optical laminate according to item 1 or 2, wherein,

the area of the plurality of concave portions is 0.3% or more and 80% or less of the area of the 1 st optical sheet when the 1 st optical sheet is viewed from the normal direction of the 1 st main surface.

[ item 4]

The optical laminate according to any one of items 1 to 3, wherein,

the plurality of concave portions may have a triangular cross section, a quadrangular cross section, or a cross section at least a part of which has a curved shape.

[ item 5]

The optical laminate according to any one of items 1 to 4, which has a haze value of 5.0% or less.

[ item 6]

The optical laminate according to any one of items 1 to 5, wherein,

the adhesive layer is any one of the following adhesive layers Aa, ab and Ac,

in a creep test using a rotary rheometer, the adhesive layer Aa has a creep deformation rate of 10% or less when a stress of 10000Pa is applied at 50 ℃ for 1 second and a creep deformation rate of 16% or less when a stress of 10000Pa is applied at 50 ℃ for 30 minutes,

The adhesive layer Aa has a 180 DEG peel adhesion force of 10mN/20mm or more with respect to the PMMA film;

the adhesive layer Ab is formed by curing a curable resin of an adhesive composition comprising a polymer and the curable resin,

the adhesive layer Ab has an initial tensile modulus at 23 ℃ of 0.35MPa or more and 8.00MPa or less before curing the curable resin of the adhesive composition,

after curing the curable resin of the adhesive composition, the adhesive layer Ab has an initial tensile modulus of 1.00MPa or more at 23 ℃;

the adhesive layer Ac 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 which is at least one selected from the group consisting of an organozirconium compound, an organoiron compound and an organoaluminum compound,

the adhesive layer Ac has a gel fraction of 40% or more after being kept at a temperature of 85 ℃ and a relative humidity of 85% for 300 hours,

the adhesive layer Ac has a 180 DEG peel adhesion force of 100mN/20mm or more with respect to the PMMA film.

[ item 7]

The optical laminate according to any one of items 1 to 6, wherein,

the adhesive layer contains at least one of the following polymers (1) to (3):

(1) Copolymers of a nitrogen-containing (meth) acrylic monomer with at least one other monomer;

(2) Copolymers of carboxyl group-containing acrylic monomers with at least one other monomer (with the exception of nitrogen-containing (meth) acrylic monomers);

(3) Polyester-based polymers.

[ item 8]

The optical laminate according to any one of items 1 to 7, further comprising a 2 nd optical sheet, wherein the 2 nd optical sheet is disposed on a side of the adhesive layer opposite to the 1 st optical sheet side.

[ item 9]

The optical laminate according to any one of items 1 to 8, wherein,

each of the plurality of concave portions has a 1 st inclined surface and a 2 nd inclined surface opposite to the 1 st inclined surface, the 1 st inclined surface directs a part of light propagating in the adhesive layer to the 2 nd main surface side of the 1 st optical sheet by total internal reflection,

in each of the plurality of concave portions, the height of the adhesive layer on the 1 st inclined surface of the concave portion is the maximum value of the height of the adhesive layer existing in the concave portion.

[ item 10]

The optical laminate according to item 9, wherein,

the inclination angle θa of the 1 st inclined surface is larger than the inclination angle θb of the 2 nd inclined surface.

[ item 11]

An optical device comprising the optical laminate according to any one of items 1 to 10.

ADVANTAGEOUS EFFECTS OF INVENTION

According to an embodiment of the present invention, there are provided an optical laminate having an adhesive layer in which penetration into recesses of a concave-convex structure of an optical sheet is suppressed, and an optical device having such an optical laminate.

Drawings

Fig. 1A is a schematic cross-sectional view of an optical stack 100A according to an embodiment of the present invention.

Fig. 1B is a schematic cross-sectional view of an optical stack 101A according to another embodiment of the present invention.

Fig. 2 is a schematic cross-sectional view of the optical stack 100A.

Fig. 3 is a schematic perspective view of the 1 st 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 layered body 100A.

Fig. 4B is a schematic cross-sectional view of an illumination device 200B including the optical layered body 100A.

Fig. 5A is a schematic cross-sectional view of an optical stack 100B1 according to another embodiment of the present invention.

Fig. 5B is a schematic cross-sectional view of an optical stack 100B2 according to still another embodiment of the present invention.

Fig. 5C is a schematic cross-sectional view of an optical stack 100B3 according to still another embodiment of the present invention.

Fig. 6A is a schematic cross-sectional view of an optical laminate 900A of a comparative example.

Fig. 6B is a schematic cross-sectional view of an optical laminate 900B of a comparative example.

Fig. 7 is a diagram showing a typical example of the result obtained by measuring the light distribution characteristics of the illumination device having the optical layered body.

Fig. 8A is a schematic plan view of the concave-convex shaping film 70 included in the optical laminate according to the embodiment of the present invention.

Fig. 8B is a schematic cross-sectional view of the concave-convex shaping film 70.

Fig. 9A is a schematic plan view of the concave-convex shaping film 82 included in the optical laminate according to the embodiment of the present invention.

Fig. 9B is a schematic cross-sectional view of the concave portion 84 of the concave-convex shaped film 82.

Fig. 9C is a schematic plan view of the concave portion 84 of the concave-convex shaped film 82.

Symbol description

10a 1 st optical sheet

12s, 18s main surface (surface)

20a, 20b adhesive layer

60. Light source

80. Light guiding layer

100A, 100B1, 100B2, 100B3, 101A, 102A optical laminate

200A, 200B lighting device

Detailed Description

An optical laminate and an optical device having the same according to an embodiment of the present invention will be described. The embodiments of the present invention are not limited to the embodiments illustrated below.

An optical laminate according to an embodiment of the present invention includes an optical sheet, and an adhesive layer disposed on a 1 st main surface side of the optical sheet, wherein the optical sheet includes a 1 st main surface and a 2 nd main surface on the opposite side of the 1 st main surface, and the 1 st main surface has a concave-convex structure. First, an example in which an adhesive layer adhered to a surface (1 st main surface) of an optical sheet having a concave-convex structure does not intrude into a concave portion of the concave-convex structure will be described with reference to fig. 1A, 1B, 2, 3, 4A, and 4B.

Fig. 1A shows a schematic cross-sectional view of an optical stack 100A according to an embodiment of the present invention. Fig. 1B shows a schematic cross-sectional view of an optical stack 101A according to an embodiment of the present invention. Fig. 2 is a schematic cross-sectional view showing an enlarged part of the optical stack 100A. Fig. 3 is a schematic perspective view of the 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 layered body 100A.

As shown in fig. 1A, the optical laminate 100A includes a 1 st optical sheet 10A and an adhesive layer 20A disposed on the 1 st principal surface 12s side of the 1 st optical sheet 10A, the 1 st optical sheet 10A includes a 1 st principal surface 12s and a 2 nd principal surface 18s on the opposite side of the 1 st principal surface 12s, and the 1 st principal surface 12s has a concave-convex structure. The concave-convex structure of the 1 st main surface 12s includes a plurality of concave portions 14 and flat portions 10s between adjacent concave portions 14 of the plurality of concave portions 14, and the adhesive layer 20a contacts the flat portions 10 s. The surface of the adhesive layer 20a and the 1 st main surface 12s of the 1 st optical sheet 10a define an internal space 14a in each of the plurality of recesses 14.

As shown in fig. 1B, the optical laminate 101A includes an optical laminate 100A and a 2 nd optical sheet 30 disposed on the opposite side of the adhesive layer 20A from the 1 st optical sheet 10A side. Unless otherwise specified, the description of the optical laminate 100A is also applicable to the optical laminate 101A, and therefore, in order to avoid repetition, the description may be omitted.

The 2 nd optical sheet 30 included in the optical laminate 101A has a main surface 38s on the adhesive layer 20a side and a main surface 32s on the opposite side of the main surface 38s, and 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 2 nd optical sheet 30 of the optical laminate 101A opposite to the adhesive layer 20a (i.e., on the main surface 32 s). The other optical member (optical sheet) includes, for example, a diffusion plate, a light guide plate, and the like, and is adhered to the main surface 32s of the optical sheet 30 via an adhesive layer.

In the example of fig. 1A and 2, the adhesive layer 20a does not intrude into the recess 14. That is, the adhesive layer 20a is not present in the space defined by the recess 14. The space defined by the concave portion 14 is defined by the concave portion 14 and a sheet surface (a surface parallel to the XY plane) including the flat portion 10s adjacent to the concave portion 14. Accordingly, the internal space 14a defined by the 1 st optical sheet 10 a-side surface 28s of the adhesive layer 20a and the 1 st main surface 12s of the 1 st optical sheet 10a coincides with the space defined by the recess 14 in this example. The interior space 14a is sometimes referred to as an air cavity or an optical cavity. The internal space 14a is typically a void portion filled with air therein. However, instead of air, the inner space 14a may be filled with a material having a lower refractive index than the 1 st optical sheet 10a and the adhesive layer 20a. When the optical sheet is viewed in a plan view (XY plane) from a normal direction of the main surface, the plurality of internal spaces may be provided discretely in the Y direction as in the example of fig. 3 with internal spaces continuous in the X direction (for example, triangular prism-shaped grooves extending in the X direction) or may be provided discretely in the X direction and the Y direction as in the example of fig. 8A. As shown in fig. 4A and 4B described later, in the lighting device having the optical laminate 100A, the light guiding direction of the light guiding layer 80 is the-Y direction. Light propagates in various directions in the light guide layer 80, but light having a component (other than zero) in the-Y direction propagates in the-Y direction, which is referred to as the-Y direction.

The optical laminate 100A functions as a light distribution structure described in patent documents 2 and 3. The optical laminate 100A has a plurality of internal spaces 14a forming interfaces for directing light in the Z direction (lower side in the drawing) by total internal reflection. The internal space 14a is defined by the surface 16s and the surface 17s that are part of the 1 st main surface 12s of the 1 st optical sheet 10a, and the surface 28s on the 1 st optical sheet 10a side of the adhesive layer 20 a. Here, the cross-sectional shape of the internal space 14a (the shape of a cross-section perpendicular to the X-direction and parallel to the YZ-plane) is triangular. The interface formed by the inclined surface 16s functions as an interface for directing light in the Z direction (lower side in the drawing) by total internal reflection. Each of the plurality of concave portions 14, that is, the plurality of internal spaces 14a has an inclined surface (1 st inclined surface) 16s that faces a part of light propagating in the optical laminate 100A toward the 2 nd principal surface 18s side (Z direction in the drawing) of the 1 st optical sheet 10A by total internal reflection, and an inclined surface (2 nd inclined surface) 17s opposite to the inclined surface 16 s. The inclination angle θa of the inclined surface 16s is, for example, 10 ° or more and 70 ° or less, and the lower limit thereof is preferably 30 ° or more, more preferably 45 ° or more. When the inclination angle θa is smaller than 10 °, the controllability of the light distribution may be reduced, and the light extraction efficiency may be reduced. On the other hand, when the inclination angle θa exceeds 70 °, for example, processing of the shaping film may become difficult. The inclination angle θb of the inclined surface 17s is, for example, 50 ° or more and 100 ° or less, and the lower limit thereof is preferably 70 ° or more. If the inclination angle θb is smaller than 50 °, stray light may be generated in an undesired direction. On the other hand, when the inclination angle θb exceeds 100 °, for example, processing of the shaping film may become difficult. The inclination angle θa of the inclined surface 16s and the inclination angle θb of the inclined surface 17s are angles with respect to the direction parallel to the Y direction in the cross section of the concave portion 14 (the 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 the lighting device (see fig. 4A and 4B) having the optical laminate 100A, the inclined surface 16s is disposed closer to the light source 60 than the inclined surface 17s. The cross-sectional shape of the internal space 14a (cross-sectional shape perpendicular to the X-direction and parallel to the YZ-plane) is defined 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 14a (the concave portion 14) is not limited to the illustrated shape, and various changes may be made. By adjusting the shape, size, arrangement density, and the like of the internal space 14a (concave portion 14), the distribution (light distribution) of the light emitted from the optical laminate 100A can be adjusted (for example, refer to patent documents 2 and 3).

The optical layered body functioning as the light distribution control structure may constitute a light guide layer and/or a direction conversion layer having a plurality of internal spaces. For example, as shown in fig. 4A, the optical laminate 100A is used for an illumination device 200A, and the illumination device 200A includes the optical laminate 102A and the light source 60. The optical laminate 102A includes an optical laminate 100A and a light guide layer 80 provided on the opposite side of the 1 st optical sheet 10A side of the adhesive layer 20A of the optical laminate 100A. The light guide layer 80 is attached to, for example, the surface 22s of the adhesive layer 20a on the opposite side of the 1 st optical sheet 10 a. The light guide layer 80 includes a 1 st main surface 80a, a 2 nd main surface 80b opposite to the 1 st main surface 80a, and a light receiving portion 80c for receiving 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 and used. As shown by arrows in fig. 4A, a part of the light introduced into the light guide layer 80 is totally internally reflected (Total Internal Reflection: TIR) at the interface 16s and the interface 14s formed by the internal space 14A. The light totally internally reflected at the interface 14s (the 1 st optical sheet side surface 28s of the adhesive layer 20 a) 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 from the 2 nd main surface 18s side of the 1 st optical sheet 10a to the outside of the optical laminate 102A.

Here, the refractive indices of the light guide layer 80, the adhesive layer 20a, and the 1 st optical sheet 10a are preferably substantially equal to each other. 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 1 st optical sheet 10a are, for example, preferably 0.20 or less, more preferably 0.15 or less, and still more preferably 0.10 or less, independently of each other.

The thickness of the adhesive layer 20a is, for example, 0.01 μm or more and 15.0 μm or less, the lower limit thereof is preferably 4.0 μm or more, and the upper limit thereof is preferably 11.0 μm or less, more preferably 9.0 μm or less. The thickness of the adhesive layer refers to the thickness of the 1 st main surface 12s of the 1 st optical sheet 10a on the flat portion 10s, unless otherwise specified.

The haze value of the optical laminate 100A is, for example, 5.0% or less. The haze value can be measured by using a haze meter (device name "HZ-1", manufactured by SUGA test Co., ltd.) and using D65 light, for example.

As in the illumination device 200B shown in fig. 4B, the light guide layer 80 may be provided on the 1 st optical sheet 10A side (closer to the 1 st optical sheet 10A than the adhesive layer 20A) of the optical laminate 100A. The light guide layer 80 and the 1 st optical sheet 10a may be adhered together via an adhesive layer. In the same manner as in the illumination device 200B, light totally internally reflected at the interface 14s (the 1 st optical sheet side surface 28s of the adhesive layer 20B) propagates in the adhesive layer 20a, and light totally internally reflected at the inclined surface 16s is emitted from the 2 nd main surface 18s side of the 1 st optical sheet 10a to the outside of the optical laminate 102B.

The lighting device of the embodiment of the present invention is not limited to the above example, and various modifications may be made. For example, a base material layer may be provided on the opposite side of the optical laminate 100A of the lighting device 200A from the light guide layer 80. Instead of the base material layer, an antireflection layer may be provided, and instead of the base material layer, a hard coat layer (for example, pencil hardness of H or more) may be provided. An anti-reflective layer and/or a hard coat layer may be provided on the substrate layer. In addition, an antireflection layer and/or a hard coat layer may be provided on the side (upper side in the drawing) of the light guide layer 80 opposite to the exit surface. The anti-reflection layer and the hard coat layer may be formed using a known material and by a known method. A low refractive index layer may be disposed between the optical stack 102A and the substrate layer (or the anti-reflective layer and/or the hard coat layer).

In the example of the illumination device 200B, a base material layer may be provided on the opposite side of the optical laminate 100A from the light guide layer 80. Instead of the base material layer, an antireflection layer and/or a hard coat layer (for example, pencil hardness of H or more) may be provided, and an antireflection layer and/or a hard coat layer may be provided on the base material layer. In addition, an antireflection layer and/or a hard coat layer may be provided on the exit surface side (lower side in the drawing) of the light guide layer 80. A low refractive index layer may be disposed between the optical stack 102B and the substrate layer (or the anti-reflective layer and/or the hard coat layer).

As shown in fig. 3, the 1 st optical sheet 10a has a plurality of concave portions 14 extending in the X direction and continuing in the X direction when viewed from the normal direction of the 1 st main surface 12 s. The plurality of concave portions 14 are arranged discretely in the Y direction, and flat portions 10s are provided between the concave portions 14 and the concave portions 14. In the Y direction, the concave portions 14 are preferably arranged periodically in the Y direction, with a pitch Py of, for example, 6 μm or more and 120 μm or less. The width Wy of the recess 14 is, for example, 3 μm or more and 20 μm or less, and the width Dy of the flat portion 10s is, for example, 3 μm or more and 100 μm or less. The ratio Wy/Dy of the width Wy of the concave portion 14 to the width Dy of the flat portion 10s is, for example, 0.3 to 7. The depth C of the recess 14 (depth in the Z direction) is, for example, 1 μm or more and 100 μm or less, and the depth C of the recess 14 is preferably 20 μm or less, 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 still more preferably 8 μm or more.

In terms of the density of the plurality of concave portions 14, when the 1 st optical sheet 10a is viewed from the normal direction of the 1 st main surface 12s, the ratio (occupied area ratio) of the area of the plurality of concave portions 14 to the area of the 1 st optical sheet 10a is preferably 0.3% or more from the viewpoint of obtaining good luminance. The area ratio of the plurality of concave portions 14 may be appropriately selected depending on the application, and is preferably 0.3% or more and 10% or less, more preferably 0.5% or more and 4% or less in the application requiring transparency, and is preferably 30% or more and 80% or less in the application requiring higher brightness. The occupied area ratio of the plurality of concave portions 14 may be uniform, or may be increased with increasing distance so that the luminance does not decrease even if the distance from the light source (for example, the light source 60 of fig. 4A or 4B) increases.

For example, the concave-convex shaping film 70 (optical sheet) shown in fig. 8A and 8B may be used instead of the 1 st optical sheet 10a. The concave-convex shaping film 70 has a main surface having a concave-convex structure, and the concave-convex structure has a plurality of concave portions 74 and flat portions 72s between adjacent concave portions 74. When the shaping film 70 is viewed from a normal direction of the main surface (see fig. 8A, for example), the plurality of concave portions 74 are arranged in an island shape in the X direction and the Y direction. In the shaping film 70, the size of the recess 74 (length L, width W: see FIGS. 8A and 8B) is preferably 10 μm or more and 500 μm or less, and the width W is preferably 1 μm or more and 100 μm or less, for example. 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 concave portion 74 is preferably 20 μm or less, more preferably 12 μm or less, and the depth H of the concave portion 74 is preferably 4 μm or more, more preferably 6 μm or more, and still more preferably 8 μm or more. In the case where the plurality of concave portions 74 are distributed discretely and uniformly, for example, it is preferable to arrange the concave portions periodically as shown in fig. 8A. The pitch Px is preferably, for example, 10 μm or more and 500 μm or less, and the pitch Py is preferably, for example, 10 μm or more and 500 μm or less. The plurality of concave portions may be disposed discretely in the light guiding direction of the light guiding layer and the direction intersecting the light guiding direction of the light guiding layer when used in the lighting device, not limited to the example of fig. 8A.

In terms of obtaining good brightness, the ratio (occupied area ratio) of the area of the plurality of concave portions 74 to the area of the molding film 70 is preferably 0.3% or more when the molding film 70 is viewed from the normal direction of the main surface (fig. 8A) in terms of the density of the plurality of concave portions 74. The occupied area ratio of the plurality of concave portions 74 may be appropriately selected depending on the application, and is preferably 30% or less in terms of obtaining good visible light transmittance and haze value in the application requiring transparency, and is preferably 1% or more, and is more preferably 25% or less in terms of obtaining good brightness, and is preferably 10% or less, and is more preferably 5% or less, for obtaining high visible light transmittance, for example, preferably 0.3% or more and 10% or less, and is more preferably 0.5% or more and 4% or less in the application requiring higher brightness. The occupied area ratio of the plurality of concave portions 74 may be uniform or may be increased with increasing distance so that the luminance does not decrease even if the distance from the light source (for example, the light source 60 of fig. 4A or 4B) is increased.

Although the cross-sectional shape of the concave portion 14 is shown as a triangle, the cross-sectional shape of the concave portion 14 is not limited to this, and may be a quadrangle (e.g., trapezoid) as long as it has a surface that can form an interface for directing light in the Z direction by total internal reflection. The shape is not limited to a polygon, and may include a curve.

For example, the concave-convex shaping film 82 (optical sheet) shown in fig. 9A may be used instead of the 1 st optical sheet 10a. The light source 60 is shown incorporated in fig. 9A. The concave-convex shaping film 82 has a main surface having a concave-convex structure, and the concave-convex structure has a plurality of concave portions 84 and flat portions 82s between adjacent concave portions 84. The plurality of concave portions 84 each have a 1 st inclined surface 86s and a 2 nd inclined surface 87s on the opposite side of the 1 st inclined surface 86s, and the 1 st inclined surface 86s directs a part of light propagating in the optical stack in the Z direction by total internal reflection. As shown in fig. 9A, the 1 st inclined surface 86s of the concave portion 84 forms a curved surface protruding toward the light source 60 side when viewed from a normal direction of the main surface having the concave-convex structure of the concave-convex shaping film 82. 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 has diffusivity with respect to the Y direction, and therefore, when the 1 st inclined surface 86s has a curved surface protruding toward the light source LS side, the 1 st inclined surface 86s acts more uniformly on the light. When a coupling optical system is provided between the light source 60 and the light receiving portion 80c of the light guide layer 80 and light having a high degree of parallelism (light having a small diffusivity with respect to the Y direction) is made incident, the 1 st inclined surface 86s may be parallel to the X direction. The preferable ranges of the size (length L, width W: see fig. 9B and 9C) and depth H (see fig. 9C) of the concave portion 84 and the pitches Px and Py are, for example, the same as those of the concave portion 74 of the concave-convex forming film 70.

The optical laminate 100A can be manufactured by, for example, adhering the adhesive layer 20A to the surface 12s having the concave-convex structure of the 1 st optical sheet 10A by a roll-to-roll method. From the viewpoint of mass productivity, the optical laminate 100A is preferably manufactured by a roll-to-roll method.

Next, an example in which an adhesive layer adhered to a surface (1 st main surface) of an optical sheet having a concave-convex structure intrudes into a concave portion of the concave-convex structure will be described with reference to fig. 5A, 5B, 5C, 6A, and 6B.

Fig. 5A is a schematic cross-sectional view of an optical stack 100B1 according to another embodiment of the present invention, and fig. 5B is a schematic cross-sectional view of an optical stack 100B2 according to yet another embodiment of the present invention. Fig. 5C is a schematic cross-sectional view of an optical stack 100B3 according to yet another embodiment of the present invention. Fig. 6A is a schematic cross-sectional view of the optical laminate 900A of the comparative example, and fig. 6B is a schematic cross-sectional view of the optical laminate 900B of the comparative example. Fig. 5A, 5B, 5C, 6A, and 6B are each enlarged views of the periphery of the recess 14. The optical laminates 100B1, 100B2, and 100B3 are different from the optical laminate 100A in the shape of the adhesive layer 20B. In the optical layered bodies 100B1, 100B2, and 100B3, the adhesive layer 20B intrudes into the concave portion 14 of the concave-convex structure of the 1 st optical sheet 10a, and therefore, the internal space 14a defined by the surface 28s of the adhesive layer 20B on the 1 st optical sheet 10a side and the 1 st main surface 12s of the 1 st optical sheet 10a does not coincide with the space defined by the concave portion 14. The optical laminates 900A and 900B of the comparative example are different from the optical laminate 100A in the shape of the adhesive layer 90.

In the optical laminate 100B1 of fig. 5A, each of the plurality of concave portions 14 satisfies 0.10 (C-se:Sub>A)/C (C) 1.00 (hereinafter, sometimes referred to as "formulse:Sub>A (I)") and 0.75 (C-se:Sub>A)/(C-B) (hereinafter, sometimes referred to as "formulse:Sub>A (II)") with the maximum value of the height of the adhesive layer 20B existing in the concave portion 14 being se:Sub>A, the minimum value of the height of the adhesive layer 20B existing in the concave portion 14 being B, and the depth of the concave portion 14 being C. The optical laminate satisfying the formulas (I) and (II) can suppress the influence on the light distribution control caused by the penetration of the adhesive layer into the concave portion even if the adhesive layer penetrates into the concave portion, and can function as a light distribution control structure. The optical layered body 100B2 of fig. 5B and the optical layered body 100B3 of fig. 5C are other examples satisfying the formulas (I) and (II), and the optical layered bodies 900A and 900B of the comparative examples of fig. 6A and 6B are examples not satisfying the formulas (I) and (II). In the optical laminate 100A described above, a=b=0, and the optical laminate 100A also satisfies the formulas (I) and (II). The depth C of the recess 14 is the length of the recess 14 in the Z direction in the cross-sectional shape of the recess 14 (the shape of the cross-section perpendicular to the X direction and parallel to the YZ plane in the drawing). The height of the adhesive layer 20b in the recess 14 is determined based on the flat portion 10s, with the height of the adhesive layer 20b in the Z direction being the height of the adhesive layer 20b in the cross section of the recess 14 (the cross section perpendicular to the X direction and parallel to the YZ plane). A, B and C of the formulas (I) and (II) can be obtained by measuring the cross-sectional images of the recess 14 as described in examples described later. For example, it is preferable to arbitrarily select the cross-sectional images of 3 recesses 14, measure A, B and C of the formulae (I) and (II) for them, and calculate the average value thereof.

The expression (C-A)/C of formulse:Sub>A (I) represents the degree to which the adhesive layer fills the concave portion 14 of the concave-convex structure of the optical sheet. Further, the ratio (degree) of the adhesive layer covering the inclined surface 16s forming the interface for directing light in the Z direction by total internal reflection is shown. The portion of the inclined surface 16s exposed from the adhesive layer may form an interface for directing light in the Z direction by total internal reflection. As in the optical laminate 100A shown in fig. 2, a=0, i.e., (C-se:Sub>A)/c=1, in the case where the adhesive layer 20A does not intrude into the concave portion 14. As in the optical laminate 900A of the comparative example of fig. 6A, when the concave portion 14 is completely filled with the adhesive layer 90A, no internal space is formed that constitutes the light distribution control structure. At this time, a=c, i.e., (C-se:Sub>A)/c=0. The smaller (C-A)/C is, the lower the light extraction efficiency is, and therefore, the lower the luminance is. When (C-A)/C is less than 0.10, the luminance may be insufficient, and the optical device (lighting device) may not be used. From the viewpoint of light distribution characteristics, particularly from the viewpoint of brightness, the closer (C-A)/C is to 1, the more preferable. For example, (C-A)/C is preferably 0.30 or more, more preferably 0.50 or more, more preferably 0.70 or more, more preferably 0.80 or more, and still more preferably 0.85 or more.

The formulse:Sub>A (C-se:Sub>A)/(C-B) of (II) is used as an index indicating the slope of the surface 28s (interface with the air layer) of the adhesive layer 20B that intrudes into the concave portion 14. The closer (C-se:Sub>A)/(C-B) is to 1, the closer the surface 28s of the adhesive layer 20B in the concave portion 14 (interface with the air layer) is to be parallel to the sheet surface (XY plane), and therefore, the function as an interface for causing total internal reflection of light propagating in the adhesive layer 20B can be maintained. For example, the optical layered body 100B2 of fig. 5B is an example of a=b, that is, (C-se:Sub>A)/(C-B) =1. Since the surface 28s of the adhesive layer defining the internal space 14a is parallel to the sheet surface, the light propagating in the adhesive layer 20a is totally internally reflected at the surface 28s of the adhesive layer 20 a. In the example of the optical laminate 100B2 of fig. 5B, the concave portion 14 is partially buried, that is, (C-se:Sub>A)/C is smaller than the optical laminate 100 se:Sub>A of fig. 2, and therefore, the light extraction efficiency is reduced compared to the optical laminate 100 se:Sub>A of fig. 2, but the difference in the light distribution is small. In the optical layered body 100B1 of fig. 5A and the optical layered body 100B3 of fig. 5C, the surface 28s (interface with the air layer) of the adhesive layer 20B in the concave portion 14 can function as an interface for causing total internal reflection of light propagating in the adhesive layer 20B. The smaller (C-se:Sub>A)/(C-B), the larger the slope of the surface of the adhesive layer 20B in the concave portion 14 with respect to the sheet surface (XY plane). The optical laminate 900B of the comparative example of fig. 6B schematically shows an example that does not satisfy the formula (II). As in the optical laminate 900B of the comparative example, when the surface 98s of the adhesive layer 90B in the concave portion 14 is greatly inclined with respect to the sheet surface, as shown by the arrow in fig. 6B, total internal reflection does not occur on the surface 98s of the adhesive layer 90B, and light propagating in the adhesive layer enters the internal space 14a, which causes leakage of light (stray light) in directions other than the desired emission direction.

The cross-sectional shape of the concave portion 14 is not limited to a triangle, and may be, for example, a quadrangle (e.g., a trapezoid) as long as it has an interface for directing light in the Z direction by total internal reflection. The shape is not limited to a polygon, and may be a shape at least a part of which has a curved line. At least a part of the curved line has a shape including a part of a circumference of a circle or an ellipse, or a combination of a plurality of curved lines having different curvatures. In any case, if the formulas (I) and (II) are satisfied, the influence on the light distribution control can be suppressed.

In the example of the optical laminate 100B1 of fig. 5A, the maximum value a of the height of the adhesive layer 20B in the concave portion 14 is the height of the adhesive layer 20B on the inclined surface 16s, and the minimum value B of the height of the adhesive layer 20B in the concave portion 14 is, for example, the height of the adhesive layer 20B on the inclined surface 17 s. In this case, the formula (I) and the formula (II) may be represented as follows. Each of the plurality of concave portions 14 has an inclined surface (1 st inclined surface) 16s and an inclined surface (2 nd inclined surface) 17s on the opposite side from the inclined surface 16s, and the inclined surface 16s directs a part of light propagating in the optical laminate toward the 2 nd main surface 18s side (Z direction in the drawing) of the 1 st optical sheet 10a by total internal reflection, and when the height of the adhesive layer 20b on the 1 st inclined surface 16s of the concave portion 14 is Dx, the height of the adhesive layer 20b on the 2 nd inclined surface 17s of the concave portion 14 is Dy, and the depth of the concave portion 14 is C, each concave portion satisfies 0.10 (C-Dx)/C (c—dx)/C (C) 1.00) (hereinafter, referred to as "formula (Ia)") and 0.75 (C-Dx)/(C-Dy) (hereinafter, referred to as "formula (IIa)"). The upper limit of (C-Dx)/(C-Dy) is not particularly limited, but is preferably 2.0 or less, more preferably 1.5 or less, and further preferably 1.2 or less from the viewpoint of light distribution characteristics. However, the present invention is not limited to the example of fig. 5A, and for example, as in the optical laminate 100B3 of fig. 5C, the height of the adhesive layer 20B on the inclined surface 17s may be the maximum value a of the height of the adhesive layer 20B in the concave portion 14, and the height of the adhesive layer 20B on the inclined surface 16s may be the minimum value B of the height of the adhesive layer 20B in the concave portion 14.

[ example of preferable composition of adhesive layer ]

Specific examples of the adhesive layer included in the optical laminate according to the embodiment of the present application are as follows. The adhesive layers Aa, ab, and Ac described below can suppress intrusion into the concave and convex recesses and change with time when adhered to the surface of the optical sheet having the concave and convex structure, and thus can be suitably used in the optical laminate according to the embodiment of the present application. The adhesive layer included in the optical laminate according to the embodiment of the present application is not limited to the following examples.

(1) Adhesive layer Aa

International publication No. 2021/167090 by the present inventors describes an adhesive layer (hereinafter, sometimes referred to as "adhesive layer Aa") having a creep deformation rate of 10% or less when a stress of 10000Pa is applied for 1 second at 50 ℃ and a creep deformation rate of 16% or less when a stress of 10000Pa is applied for 30 minutes at 50 ℃ in a creep test using a rotary rheometer, and having a 180 ° peel adhesion force of 10mN/20mm or more with respect to a PMMA film. According to the study of the present inventors, when an adhesive layer is adhered to a surface of an optical sheet having a concave-convex structure, there is a correlation between the degree of penetration into a concave portion and its change with time and the creep deformation rate of the adhesive layer. Specifically, in the creep test using the rotary rheometer, the adhesive layer having a creep deformation rate of 10% or less when a stress of 10000Pa is applied at 50 ℃ for 1 second can suppress the degree of penetration into the concave portion of the concave-convex structure when adhered to the surface having the concave-convex structure, and in the creep test using the rotary rheometer, the adhesive layer having a creep deformation rate of 16% or less when a stress of 10000Pa is applied at 50 ℃ for 30 minutes (1800 seconds) can suppress the change with time of the degree of penetration into the concave portion of the concave-convex structure. The disclosure of International publication No. 2021/167090 is incorporated herein by reference in its entirety.

(2) Adhesive layer Ab

International publication No. 2021/167091 by the present inventors describes an adhesive layer (hereinafter, also referred to as "adhesive layer Ab") formed by curing a curable resin comprising a polymer and a curable resin adhesive composition, the polymer comprising a copolymer of at least one (meth) acrylate monomer and at least one monomer comprising a copolymerizable functional group selected from the group consisting of a hydroxyl-containing copolymerizable monomer, a carboxyl-containing copolymerizable monomer and a nitrogen-containing vinyl monomer, wherein the adhesive layer has an initial tensile modulus of 0.35MPa to 8.00MPa at 23 ℃ before curing the curable resin of the adhesive composition and an initial tensile modulus of 1.00MPa or more at 23 ℃ after curing the curable resin of the adhesive composition. When the adhesive layer 20a is formed, that is, when the adhesive composition layer is provided on the 1 st main surface 12s of the optical sheet 10a, the adhesive composition is prevented from entering the plurality of concave portions by setting the initial tensile modulus of the adhesive composition at 23 ℃ to 0.35MPa or more before the curable resin is cured. By setting the initial tensile modulus of the adhesive composition at 23 ℃ to 8.00MPa or less before curing the curable resin of the adhesive composition, the adhesive composition layer has a desired flexibility (easy deformability) to be imparted to the 1 st main surface 12s of the optical sheet 10 a. By setting the initial tensile modulus at 23 ℃ to 1.00MPa or more after curing the curable resin of the adhesive composition, the adhesive layer 20a can be prevented from deforming with time into the plurality of concave portions after forming the adhesive layer 20 a. The disclosure of International publication No. 2021/167091 is incorporated herein by reference in its entirety.

The polymer contained in the adhesive composition includes, for example, a copolymer of at least one (meth) acrylate monomer (e.g., alkyl (meth) acrylate) and at least one monomer containing a copolymerizable functional group selected from the group consisting of a hydroxyl group-containing copolymerizable monomer, a carboxyl group-containing copolymerizable monomer, and a nitrogen-containing vinyl monomer. In the case where the at least one copolymerizable functional group-containing monomer comprises a nitrogen-containing vinyl monomer, the mass 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).

The adhesive layer Ab is formed by curing a curable resin of an adhesive composition including a polymer and a curable resin. First, an adhesive composition layer formed of an adhesive composition is provided on the 1 st main surface 12s of the optical sheet 10 a. Next, in a state where the adhesive composition layer is applied to the 1 st main surface 12s of the optical sheet 10a, heat or irradiation with active energy rays is applied to the adhesive composition layer, whereby the curable resin of the adhesive composition is cured. From the viewpoint of suppressing the entry of the adhesive composition layer into the plurality of recesses, the curable resin (for example, ultraviolet curable resin) preferably has a weight average molecular weight of 4000 or more, for example.

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

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

(3) Adhesive layer Ac

Japanese patent application 2021-025496 by the present inventors describes an adhesive layer (hereinafter, sometimes referred to as "adhesive layer Ac") formed by crosslinking an adhesive composition, the adhesive layer Ac comprising a polyester resin as 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 organozirconium compound, an organoiron compound and an organoaluminum compound, the adhesive layer having a gel fraction of 40% or more after being held at a temperature of 85 ℃ and a relative humidity of 85% for 300 hours, and a 180 DEG peel adhesion force to a PMMA film of 100mN/20mm or more. The adhesive layer Ac can suppress the change with time even under high temperature and high humidity. The disclosure of Japanese patent application 2021-025496 is incorporated by reference in its entirety into this specification.

The following adhesives may be used as the adhesives for forming the adhesive layers Aa and Ab.

The adhesive contains, for example, a (meth) acrylic polymer such as 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. If the (meth) acrylic polymer is produced using a nitrogen-containing (meth) acrylic monomer, the effect of improving the elastic properties of the (meth) acrylic polymer can be obtained particularly when the nitrogen-containing (meth) acrylic monomer has a nitrogen-containing cyclic structure.

In the case where the adhesive contains a (meth) acrylic polymer, the (meth) acrylic polymer is preferably crosslinked. In the case where the adhesive contains a (meth) acrylic polymer, the adhesive may further contain an active energy ray-curable resin (for example, an ultraviolet ray-curable resin) and a curing agent (for example, a photopolymerization initiator), or may further contain a cured product of the active energy ray-curable resin. The active energy rays are, for example, visible light and ultraviolet rays. By introducing a crosslinking structure into the adhesive, deformation and time-dependent deformation at the time of attaching the adhesive can be suppressed. In particular, by curing the active energy ray-curable resin after the adhesive composition layer (which becomes the adhesive layer 20 a) is applied to the optical sheet 10a, the change with time of the adhesive layer 20a can be suppressed, and the change with time of the extent to which the adhesive layer 20a enters the concave portion can be suppressed. If the active energy ray-curable resin is cured, the adhesive layer 20a becomes hard. If the adhesive layer 20a is too hard, it may be difficult to attach the adhesive layer 20a to the optical sheet 10a by a roll-to-roll method, but if the active energy ray-curable resin is cured after the adhesive composition layer is applied to the optical sheet 10a, this problem can be avoided.

The adhesive layer 20a containing the cured product of the active energy ray-curable resin is formed by, for example, 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 on the main surface of the base material after the release treatment, for example. Next, the solvent of the adhesive composition solution layer is removed (for example, by heating), and the (meth) acrylic polymer of the adhesive composition solution layer is crosslinked by a crosslinking agent, thereby obtaining an adhesive composition layer having a crosslinked structure. When the adhesive composition solution layer is formed on the release-treated main surface of the base material, the adhesive composition layer is formed on the release-treated main surface of the base material, and a laminate having the base material and the adhesive composition layer is obtained. Here, the crosslinked structure formed by the (meth) acrylic polymer and the crosslinking agent is referred to as a 1 st crosslinked structure, and is distinguished from a crosslinked structure formed by curing an active energy ray-curable resin (a 2 nd crosslinked structure) described later. The polymer of the adhesive composition solution layer may be crosslinked in the step of removing the solvent of the adhesive composition solution layer, or the step of crosslinking the polymer of the adhesive composition solution layer may be further performed after the step of removing the solvent of the adhesive composition solution layer separately from the step of removing the solvent of the adhesive composition solution layer. Then, the adhesive composition layer is adhered to the 1 st main surface 12s of the optical sheet 10a, and the adhesive composition layer is irradiated with an active energy ray in a state in which the adhesive composition layer is disposed on the 1 st main surface 12s of the optical sheet 10a, and the active energy ray-curable resin is cured, whereby the adhesive layer 20a having a 2 nd crosslinking structure in addition to the 1 st crosslinking structure can be formed. The 1 st and 2 nd crosslinked structures of the adhesive layer 20a are considered to form a so-called interpenetrating network structure (IPN).

The adhesive layer 20a containing no cured product of the active energy ray-curable resin is formed by, for example, 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. The adhesive composition solution does not contain an active energy ray-curable resin and a polymerization initiator. The adhesive composition solution layer is formed on the main surface of the base material after the release treatment, for example. Next, the solvent of the adhesive composition solution layer is removed (for example, by heating), and the polymer of the adhesive composition solution layer is crosslinked by a crosslinking agent, 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, the 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 of the adhesive composition solution layer may be crosslinked in the step of removing the solvent of the adhesive composition solution layer, or the step of crosslinking the polymer of the adhesive composition solution layer may be further performed after the step of removing the solvent of the adhesive composition solution layer separately from the step of removing the solvent of the adhesive composition solution layer.

The binder is preferably free of grafted polymer. If the adhesive layer is formed of an adhesive composition containing a graft polymer as described in patent document 1, there are cases where design factors and control factors of the material become large and mass productivity is poor. The creep characteristics of the adhesive without the graft polymer may be adjusted according to various factors (for example, the kind and amount of the crosslinking agent, the kind and amount of the active energy ray-curable resin).

Hereinafter, a preferable specific example of the adhesive will be described.

The adhesive contains, for example, a (meth) acrylic polymer. Any (meth) acrylate may be used as the monomer for producing the (meth) acrylic polymer, and is not particularly limited. For example, alkyl (meth) acrylates having an alkyl group having 4 or more carbon atoms can be used. In this case, the proportion of the alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms is, for example, 50% by mass or more relative to the total amount of the monomers used for producing the (meth) acrylic polymer.

In the present specification, "(meth) acrylic acid alkyl ester" means a (meth) acrylic acid ester having a linear or branched alkyl group. The number of carbon atoms of the alkyl group of the alkyl (meth) acrylate is preferably 4 or more, more preferably 4 or more and 9 or less. The term (meth) acrylate refers to an acrylate and/or a methacrylate.

Specific examples of the alkyl (meth) acrylate include n-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isopentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, isotetradecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, stearyl (meth) acrylate, and isostearyl (meth) acrylate. These alkyl (meth) acrylates may be used alone or in combination.

The adhesive may comprise a (meth) acrylic polymer as 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, with the total amount of the monomers used for copolymerization being 100 parts by mass.

Nitrogen-containing (meth) acrylic monomers: 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, it is 10.0 parts by mass or more and 40.0 parts by mass or less.

Hydroxyl-containing acrylic monomer: 0.05 part by mass or more, 0.75 part by mass or more, 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, 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.

Carboxyl group-containing acrylic monomer: 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, or 2.0 parts by mass or less. For example, 1.0 to 10.0 parts by mass.

Alkyl (meth) acrylate monomer: (100 parts by mass) - (total amount of monomers other than the alkyl (meth) acrylate monomer for copolymerization)

In the present specification, the "nitrogen-containing (meth) acrylic monomer" includes, without particular limitation, a monomer having a polymerizable functional group having an unsaturated double bond such as 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 the nitrogen-containing (meth) acrylic monomer having a nitrogen-containing cyclic structure include: n-vinyl-2-pyrrolidone (NVP), N-vinyl-epsilon-caprolactam (NVC), 4-Acryloylmorpholine (ACMO). These nitrogen-containing cyclic structures may be used alone or in combination.

In the present specification, the "hydroxyl group-containing acrylic monomer" includes, without particular limitation, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group and 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, 4-hydroxybutyl vinyl ether, and the like.

In the present specification, the "carboxyl group-containing acrylic monomer" includes, without particular limitation, a monomer having a carboxyl group and having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group. Examples of the unsaturated carboxylic acid-containing monomer include: carboxylic ethyl (meth) acrylate, carboxylic pentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and the like. These unsaturated carboxylic acid-containing monomers may be used alone or in combination.

The adhesive may comprise a (meth) acrylic polymer which is a copolymer of a carboxyl group-containing acrylic monomer and at least one other monomer except for a nitrogen-containing (meth) acrylic monomer. In this case, the (meth) acrylic polymer is preferably a copolymer obtained by copolymerizing the following monomers in the following amounts, with the total amount of the monomers used for copolymerization being 100 parts by mass.

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 91.0 parts by mass or less. For example, 90.0 parts by mass or more and 99.0 parts by mass or less.

The crosslinking agent for introducing a crosslinked structure into the (meth) acrylic polymer includes an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a silicone-based crosslinking agent, and,Oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, peroxide-based crosslinking agents, and the like. The crosslinking agent may be used singly or in combination of two or more.

The isocyanate-based crosslinking agent is a compound having 2 isocyanate groups (including an isocyanate-regenerated functional group in which an isocyanate group is temporarily protected by blocking agent or polymerization) in 1 molecule.

Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as toluene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

More specifically, examples thereof include: lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentene diisocyanate, cyclohexene diisocyanate and isophorone diisocyanate, aromatic diisocyanates such as 2, 4-toluene diisocyanate, 4' -diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate, trimethylolpropane/toluene diisocyanate trimer adduct (trade name Coronate L, manufactured by Tosoh corporation), trimethylolpropane/hexamethylene diisocyanate trimer adduct (trade name Coronate HL, manufactured by Tosoh corporation), isocyanate adduct of hexamethylene diisocyanate (trade name Coronate HX, manufactured by Tosoh corporation) and trimethylolpropane adduct of xylylene diisocyanate (trade name D110N, manufactured by Sanyo chemical corporation, trade name D160N); polyether polyisocyanates, polyester polyisocyanates, adducts thereof with various polyols, polyisocyanates obtained by polyfunctional functionalization of isocyanurate bonds, biuret bonds, allophanate bonds, and the like.

The isocyanate-based crosslinking agent may be used singly or in combination of two or more. The amount of the isocyanate-based crosslinking agent to be blended 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, 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, 0.05 parts by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the (meth) acrylic polymer. The blending amount may be appropriately adjusted in consideration of the cohesive force, prevention of peeling in the durability test, and the like.

In the aqueous dispersion of the modified (meth) acrylic polymer produced by emulsion polymerization, an isocyanate-based crosslinking agent may not be used, but if necessary, a blocked isocyanate-based crosslinking agent may be used in order to easily react with water.

The epoxy-based crosslinking agent is a polyfunctional epoxy compound having 2 or more epoxy groups in 1 molecule. Examples of the epoxy-based crosslinking agent include: bisphenol a, epichlorohydrin type epoxy resins, ethylene glycol glycidyl ether, N' -tetraglycidyl m-xylylenediamine, diglycidyl aniline, diamine glycidyl amine, 1, 3-bis (N, N-diglycidyl aminomethyl) 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, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having 2 or more epoxy groups in the molecule can be mentioned. Examples of the epoxy-based crosslinking agent include those available from Mitsubishi gas chemical corporation under the trade names "TETRAD C", "TETRAD X", and the like.

The epoxy crosslinking agent may be used alone or in combination of two or more. The amount of the epoxy-based crosslinking agent to be blended 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, 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, 0.05 parts by mass or more and 8 parts by mass or less, relative to 100 parts by mass of the (meth) acrylic polymer. The blending amount may be appropriately adjusted in consideration of the cohesive force, prevention of peeling in the durability test, and the like.

The peroxide crosslinking agent may be used as long as it is a peroxide crosslinking agent that generates a radical active species by heating and crosslinks a base polymer of the adhesive, but in view of handleability and stability, it is preferable to use a peroxide having a 1-minute half-life temperature of 80 ℃ or more and 160 ℃ or less, and more preferable to use a peroxide having a 1-minute half-life temperature of 90 ℃ or more and 140 ℃ or less.

Examples of the peroxide include: di (2-ethylhexyl) peroxydicarbonate (1-min half-life temperature: 90.6 ℃), di (4-t-butylcyclohexyl) peroxydicarbonate (1-min half-life temperature: 92.1 ℃), di (sec-butyl) peroxydicarbonate (1-min half-life temperature: 92.4 ℃), t-butyl peroxyneodecanoate (1-min half-life temperature: 103.5 ℃), t-hexyl peroxypivalate (1-min half-life temperature: 109.1 ℃), t-butyl peroxypivalate (1-min half-life temperature: 110.3 ℃), dilauroyl peroxide (1-min half-life temperature: 116.4 ℃), di (1-min half-life temperature: 117.4 ℃), 1, 3-tetramethylbutyl peroxide (1-min half-life temperature: 124.3 ℃), di (4-methylbenzoyl) (1-min half-life temperature: 128.2 ℃)), t-butyl peroxyisobutyrate (1-min half-life temperature: 109.0 ℃), 1-t-butyl peroxyiso-butyrate (1-min half-life temperature: 1-life temperature: 1.136; 1-cyclohexane (1-t-life temperature: 149 ℃), and the like. Among them, bis (4-t-butylcyclohexyl) peroxydicarbonate (1-minute half-life temperature: 92.1 ℃ C.), dilauryl 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 of particularly excellent crosslinking reaction efficiency.

The half-life of the peroxide is an index indicating the decomposition rate of the peroxide, and means the time until the residual amount of the peroxide reaches half. The decomposition temperature for obtaining the half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in the manufacturer's catalogue, for example, in "organic peroxide catalogue 9 th edition (month 5 2003) of the company of the Nikki Co., ltd.

The peroxide may be used alone, or two or more of them may be used in combination. The amount of the peroxide is 0.02 parts by mass or more and 2 parts by mass or less, preferably 0.05 parts by mass or more and 1 part by mass or less, based on 100 parts by mass of the (meth) acrylic polymer. Within this range, processability, reworkability, crosslinking stability, peelability and the like can be appropriately adjusted.

The method for measuring the peroxide decomposition amount remaining after the reaction treatment can be measured by HPLC (high performance liquid chromatography), for example.

More specifically, for example, about 0.2g of the binder after the reaction treatment may be taken out each time, immersed in 10ml of ethyl acetate, extracted by shaking at 120rpm for 3 hours at 25℃with a shaker, and then allowed to stand at room temperature for 3 days. Next, 10ml of acetonitrile was added thereto, and the mixture was shaken at 120rpm for 30 minutes at 25℃and filtered by a membrane filter (0.45 μm) to obtain an extract, and about 10. Mu.l of the obtained extract was injected into HPLC and analyzed to obtain the peroxide amount after the reaction treatment.

As the crosslinking agent, an organic crosslinking agent and a polyfunctional metal chelate compound may be used in combination. The polyfunctional metal chelate is a chelate in which a polyvalent metal and an organic compound form a covalent bond or a coordinate bond. Examples of the polyvalent metal atom include Al, cr, zr, co, cu, fe, ni, V, zn, in, ca, mg, mn, Y, ce, sr, ba, mo, la, sn, ti. The atom in the organic compound forming covalent bond or coordinate bond may be an oxygen atom, and the organic compound may be: alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

The amount of the 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 weight average molecular weight (Mw) before curing is 4000 to 50000. As the active energy ray-curable resin, for example, acrylate-based, epoxy-based, urethane-based, or thiol/alkene-based ultraviolet-curable resins can be suitably used.

As the active energy ray-curable resin, monomers and/or oligomers that undergo radical polymerization or cationic polymerization by active energy rays are used.

The monomer that undergoes radical polymerization by active energy rays includes a monomer having an unsaturated double bond such as a (meth) acryloyl group and a vinyl group, and particularly, a monomer having a (meth) acryloyl group is preferably used because of its excellent reactivity.

Specific examples of the monomer having a (meth) acryloyl group include: allyl (meth) acrylate, caprolactone (meth) acrylate, cyclohexyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, seventeen fluoro decyl (meth) acrylate, glycidyl (meth) acrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate, isobornyl (meth) acrylate, morpholinyl (meth) acrylate, phenoxyethyl (meth) acrylate, tripropylene glycol di (meth) acrylate, bisphenol a diglycidyl ether di (meth) acrylate, hydroxypivalate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxy tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and the like.

As the oligomer which is free-radically polymerized by active energy rays, polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, or the like, which is obtained by adding 2 or more unsaturated double bonds such as (meth) acryl, vinyl, or the like to a skeleton of polyester, epoxy, urethane, or the like, as the same functional group as the monomer, can be used.

The polyester (meth) acrylate is obtained by reacting (meth) acrylic acid with a polyester having a terminal hydroxyl group obtained from a polyhydric alcohol and a polyhydric carboxylic acid, and specific examples thereof include Aronix M-6000, 7000, 8000, 9000 series, etc. manufactured by eastern asia synthesis corporation.

The epoxy (meth) acrylate is obtained by reacting (meth) acrylic acid with an epoxy resin, and specific examples thereof include Lipoxy SP manufactured by sho polymer co.

The urethane (meth) acrylate is obtained by reacting a polyol, an isocyanate, and a hydroxy (meth) acrylate, and specific examples thereof include ArtResin UN series manufactured by katsumada chemical company, NK Oligo U series manufactured by new yo chemical company, and violet UV series manufactured by mitsubishi chemical company.

The photopolymerization initiator has the following effects: the multifunctional oligomer is cured by radical polymerization, which is activated and excited by irradiation with ultraviolet light to generate radicals. Examples include: 4-Phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-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 ketone, 2-methyl-1- [4- (methylthio) phenyl]-2-morpholinopropane-1 and other acetophenone photopolymerization initiators, benzoin methyl ether and benzeneSpecific photopolymerization initiators such as benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-dimethoxy-2-phenylacetophenone, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4-phenylbenzophenone, hydroxybenzophenone, benzophenone photopolymerization initiators such as 4-benzoyl-4 ' -methylbenzenesulfide, 3' -dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, 2, 4-diisopropylthioxanthone, and specific photopolymerization initiators such as α -acyloxime ester, acylphosphine oxide, methyl benzoyl benzoate, benzil, camphorquinone, dibenzocycloheptanone, 2-ethylanthraquinone, 4' -diethylisophthalophenone. As the photopolymerization initiator, allyl sulfonium hexafluorophosphate, and bis (alkylphenyl) iodo hexafluorophosphate can be used Photo cation polymerization initiator such as salt.

The photopolymerization initiator may be used in combination of two or more kinds. The polymerization initiator is blended in a range of usually 0.5 parts by mass or more and 30 parts by mass or less, more preferably 1 part by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the active energy ray-curable resin. When the amount is less than 0.5 parts by mass, polymerization may not proceed sufficiently, and when the amount exceeds 30 parts by mass, the curing rate may be slow, and the hardness of the cured sheet may be lowered.

The active energy ray is not particularly limited, and ultraviolet rays, visible rays, and electron beams are preferable. The crosslinking treatment by ultraviolet irradiation may be performed using an appropriate ultraviolet 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 amount of the ultraviolet ray may be appropriately selected depending on the degree of crosslinking required, and in general, it is desirable that the irradiation amount of the ultraviolet ray is 0.2J/cm ² Above and 10J/cm ² The following ranges are selected. The temperature at the time of irradiation is not particularly limited, and examination is madeThe heat resistance of the support is preferably about 140 ℃.

In the case where the adhesive contains a polyester-based polymer instead of the (meth) acrylic polymer or in addition to the (meth) acrylic polymer, for example, a polyester-based polymer having the following characteristics is preferable.

The kind of carboxylic acid component (or the characteristics of the skeleton, etc.): contains at least 2 carboxyl groups of dicarboxylic acid, specifically dicarboxylic acid. The dicarboxylic acid is not particularly limited, and examples thereof include: dimer acids derived from sebacic acid, oleic acid, erucic acid, and the like. As other examples, there may be mentioned 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, citraconic acid, etc., terephthalic acid, isophthalic acid, phthalic acid, 1, 5-naphthalenedicarboxylic acid, 2, 6-naphthalenedicarboxylic acid, 4' -diphenyldicarboxylic acid, 2' -diphenyldicarboxylic acid, 4' -diphenylether dicarboxylic acid. In addition to the above dicarboxylic acid, a tricarboxylic acid containing 3 or more carboxyl groups may be used.

The kind of the diol component (or the characteristics of the skeleton, etc.): at least a diol having 2 hydroxyl groups in the molecule, specifically, a diol. Dimer diols derived from fatty acid esters, oleic acid, erucic acid, and the like, glycerol monostearate, and the like. Examples of the other diols include aliphatic diols such as ethylene glycol and 1, 2-propanediol, and examples of the diols other than aliphatic diols include ethylene oxide adducts and propylene oxide adducts of bisphenol a, ethylene oxide adducts and propylene oxide adducts of hydrogenated bisphenol a, and the like.

As the crosslinking agent for introducing a crosslinked structure into the polyester-based polymer, an isocyanate-based crosslinking agent,Oxazoline-based crosslinking agent, aziridine-based crosslinking agent, silane-based crosslinking agent, and alkyl etherificationMelamine crosslinking agents, metal chelate crosslinking agents. The amount of the crosslinking agent to be blended is, for example, 2.0 parts by mass or more and 10.0 parts by mass or less relative to 100 parts by mass of the polyester-based polymer.

Hereinafter, a specific example of the composition of the adhesive layer Ac will be described.

< polycarboxylic acid >)

Examples of the polycarboxylic acid include:

aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, benzyl malonic acid, diphenic acid, 4' -oxybisbenzoic acid, and naphthalene dicarboxylic acid;

aliphatic dicarboxylic acids such as malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, 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-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 2, 5-norbornanedicarboxylic acid, and adamantanedicarboxylic acid.

These may be used alone or in combination of two or more.

Among these, aromatic dicarboxylic acids are preferably contained, and terephthalic acid or isophthalic acid is particularly preferably contained, from the viewpoint of imparting cohesive force.

< polyol >)

Examples of the polyol include:

aliphatic diols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1, 3-propanediol, 2, 4-dimethyl-2-ethylhexyl-1, 3-diol, 2-methyl-1, 3-propanediol, 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, 4-trimethyl-1, 6-hexanediol, and polytetramethylene glycol;

alicyclic diols such as 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, spiroglycol, tricyclodecanedimethanol, adamantanediol, and 2, 4-tetramethyl-1, 3-cyclobutanediol;

aromatic diols such as 4,4' -thiodiphenol, 4' -methylenediphenol, 4' -dihydroxydiphenyl, o-dihydroxybenzene, m-dihydroxybenzene, p-dihydroxybenzene, 2, 5-naphthalene diol, p-xylene diol, and ethylene oxide and propylene oxide adducts thereof.

These may be used alone or in combination of two or more.

Of these, aliphatic diols or alicyclic diols are preferably contained, and polytetramethylene glycol, neopentyl glycol or cyclohexanedimethanol are more preferably contained.

< crosslinker >

The crosslinking agent is not particularly limited, and known crosslinking agents can be used, and for example, polyisocyanurate, polyfunctional isocyanate, polyfunctional melamine compound, polyfunctional epoxy compound, and the like can be usedOxazoline compounds, polyfunctional aziridine compounds, metal chelates, and the like. In particular, an isocyanate-based crosslinking agent is preferably used from the viewpoints of transparency of the obtained adhesive layer and obtaining an elastic modulus suitable for the adhesive layer.

More specifically, examples thereof include: lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentene diisocyanate, cyclohexene diisocyanate and isophorone diisocyanate, aromatic diisocyanates such as 2, 4-toluene diisocyanate, 4' -diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate, trimethylolpropane/toluene diisocyanate trimer adduct (trade name Coronate L, manufactured by Tosoh corporation), trimethylolpropane/hexamethylene diisocyanate trimer adduct (trade name Coronate HL, manufactured by Tosoh corporation), isocyanate adduct of hexamethylene diisocyanate (trade name Coronate HX, manufactured by Tosoh corporation) and trimethylolpropane adduct of xylylene diisocyanate (trade name D110N, manufactured by Sanyo chemical corporation, trade name D160N); polyether polyisocyanates, polyester polyisocyanates, adducts thereof with various polyols, polyisocyanates obtained by polyfunctional functionalization of isocyanurate bonds, biuret bonds, allophanate bonds, and the like. If an aliphatic isocyanate is used, a high gel fraction adhesive layer can be obtained in a small amount of the crosslinking agent, and is more preferable.

The isocyanate-based crosslinking agent may be used singly or in combination of two or more. The lower limit of the amount of the isocyanate-based crosslinking agent to be incorporated 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 to be incorporated is 20 parts by mass or less, preferably 15 parts by mass or less. By setting the range to this, the adhesive layer can have a good adhesion to the surface of the concave-convex structure, and can be prevented from entering the concave portion of the concave-convex structure with time.

< crosslinking catalyst >)

Examples of the organoaluminum compound include aluminum triacetylacetonate, aluminum ethylacetoacetate diisopropoxylate, and the like.

Examples of the organic iron compound include an acetylacetonate-iron complex.

Examples of the organozirconium compound include zirconium tetra-acetylacetonate.

These may be used alone or two or more kinds may be used in combination as required.

By using the crosslinking catalyst, the crosslinking speed can be increased and the production preparation time can be shortened.

As a method for forming the adhesive layer Ac, a known method can be used. For example, the following methods are mentioned. First, an adhesive composition (or a solution containing an adhesive composition) is applied (coated) onto a support (substrate), and then dried as necessary, thereby forming an adhesive composition layer. Typically, an adhesive composition solution containing a polyester resin, a crosslinking agent, a crosslinking catalyst, and a solvent is applied to a substrate to form an adhesive composition solution layer on the substrate, and the solvent of the adhesive composition solution layer is removed to obtain an adhesive composition layer. Next, the adhesive composition layer is subjected to a crosslinking treatment (for example, a heat treatment), and the polyester resin of the adhesive composition layer is crosslinked with a crosslinking agent, thereby forming an adhesive layer having a crosslinked structure. Thus, an adhesive layer was formed on the base material, and a laminate having the base material and the adhesive layer was obtained. As the substrate, for example, a substrate having a main surface subjected to a peeling treatment such as a release liner can be used. The adhesive layer formed on the release liner by the above-described method may be transferred (transferred) to a support (or other release liner). As a method of applying the adhesive composition (adhesive composition solution) to the substrate, a known method can be used, and examples thereof include: roll coating, gravure coating, reverse roll coating, roll brushing, air knife coating, spray coating, extrusion coating using a die coater, and the like.

[ examples of preferable configurations of light guide layer, optical sheet, base layer, low refractive index layer ]

Preferred examples of the respective constituent elements of the lighting device according to the embodiment of the present invention will be described.

The light guide layer 80 may be formed of a known material having high transmittance for visible light. The light guide layer 80 is made of, for example, an acrylic resin such as polymethyl methacrylate (PMMA), a Polycarbonate (PC) resin, a cycloolefin resin, and glass (for example, quartz)Glass, alkali-free glass, borosilicate glass). Refractive index n of light guide layer 80 _GP For example, 1.40 to 1.80. Unless otherwise specified, the refractive index refers to a refractive index measured by ellipsometry at a wavelength of 550 nm. The thickness of the light guide layer 80 may be appropriately set according to the application, and the thickness of the light guide layer 80 is, for example, 0.05mm to 50 mm.

The 1 st optical sheet 10a can be produced by the method described in, for example, japanese patent application laid-open No. 2013-524288. Specifically, for example, the surface of a polymethyl methacrylate (PMMA) film may be coated with a varnish (for example, a photocurable resin such as Finecure RM-64, acrylic acid esters, made by Sanyo chemical industry Co., ltd.), an optical pattern may be embossed on the film surface containing the varnish, and the varnish may be cured (for example, ultraviolet irradiation conditions: D valve, 1000 mJ/cm) ² 、320mW/cm ² ) Thereby, the 1 st optical sheet 10a was produced.

The material of the 2 nd optical sheet 30 is, for example, a thermoplastic resin having light transmittance, and more specifically, a film formed of a (meth) acrylic resin such as polymethyl methacrylate (PMMA) or a Polycarbonate (PC) resin. The 2 nd optical sheet 30 may be made of any appropriate material according to purposes.

The thickness of the base material layer is, for example, 1 μm or more and 1000 μm or less, preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 80 μm or less. The refractive index of the base material layer is preferably 1.40 or more and 1.70 or less, more preferably 1.43 or more and 1.65 or less.

Refractive index n of low refractive index layer _L1 Each independently is, for example, preferably 1.30 or less, more preferably 1.20 or less, and still more preferably 1.15 or less. The low refractive index layer is preferably solid, and the refractive index is preferably 1.05 or more, for example. The difference between the refractive index of the light guide layer 80 and the refractive index layer of the low refractive index layer is preferably 0.20 or more, more preferably 0.23 or more, and still more preferably 0.25 or more. The low refractive index layer having a refractive index of 1.30 or less may be formed using a porous material, for example. The thickness of the low refractive index layers is, for example, independently 0.3 μm or more and 5 μm or less.

In the case where the low refractive index layer is a porous material having voids therein, the void ratio is preferably 35% by volume or more, more preferably 38% by volume or more, particularly preferably 40% by volume or more, and if the low refractive index layer is in such a range, a low refractive index layer having a particularly low refractive index can be formed. The upper limit of the void ratio of the low refractive index layer is, for example, 90% by volume or less, preferably 75% by volume or less, and if the upper limit is in this range, a low refractive index layer excellent in strength can be formed. The void fraction is a value calculated by the Lorentz-Lorenz's formula from the value of the refractive index measured by ellipsometry.

As for the low refractive index layer, for example, a low refractive index layer having voids disclosed in international publication No. 2019/146628 can be used, and the disclosure of international publication No. 2019/146628 is incorporated by reference in its entirety into the present specification. Specifically, the low refractive index layer having voids includes silica particles, silica particles having micropores, substantially spherical particles such as silica hollow nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, silica nanofibers, flat plate particles such as nanoclay composed of bentonite, and the like. In one embodiment, the low refractive index layer having voids is a porous body formed by directly chemically bonding particles (for example, fine particles) to each other. In addition, at least a part of the particles constituting the low refractive index layer having voids may be bonded to each other via a small amount (e.g., less than the mass of the particles) of the binder component. The porosity and refractive index of the low refractive index layer can be adjusted by the particle diameter, particle diameter distribution, and the like of particles constituting the low refractive index layer.

Examples of the method for obtaining a low refractive index layer having voids include those described in JP-A2010-189212, JP-A2008-040171, JP-A2006-01175, international publication No. 2004/113966, and references therein. The disclosures of JP 2010-189212A, JP 2008-040171A, JP 2006-01175A and International publication No. 2004/113966 are incorporated herein by reference in their entirety.

As the low refractive index layer having voids, a silica porous body can be suitably used, and the silica porous body is produced by, for example, the following method. A method of hydrolyzing and polycondensing at least one of a silicon compound, a hydrolyzable silane and/or a silsesquioxane, and a partial hydrolysate and a dehydrated condensate thereof; methods of using porous particles and/or hollow microparticles; and a method of generating an aerogel layer using a rebound phenomenon; a method of using a pulverized gel obtained by pulverizing a gel-like silicon compound obtained by a sol-gel method and chemically bonding fine pore particles obtained as pulverized materials to each other by a catalyst or the like; etc. However, the low refractive index layer is not limited to the silica porous body, and the production method thereof is not limited to the exemplified production method, and may be produced by any production method. The porous layer is not limited to the silica porous body, and the production method thereof is not limited to the exemplified production method, and may be produced by any production method. The silsesquioxane is a silsesquioxane represented by (RSiO) _1.5 R is a hydrocarbon radical) as basic structural unit, in particular SiO ₂ Silica, which is a basic structural unit, is different from silica, but is the same as silica in terms of having a network structure crosslinked by siloxane bonds, and therefore, a porous body containing silsesquioxane as a basic structural unit is also referred to herein as a silica porous body or a silica-based porous body.

The silica porous body may be composed of fine pore particles of gel-like silicon compounds bonded to each other. The fine pore particles of the gel-like silicon compound include pulverized gel-like silicon compound. The silica porous body can be formed, for example, by applying a coating liquid containing a pulverized product of a gel-like silicon compound to a substrate. The pulverized product of the gel-like silicon compound can be chemically bonded (for example, siloxane bonded) by, for example, the action of a catalyst, light irradiation, heating, or the like.

Examples

Production example 1

Manufacture of relief shaped film

An uneven surface-forming film was produced according to the method described in Japanese patent application laid-open No. 2013-524288. Specifically, a surface of a polymethyl methacrylate (PMMA) film was coated with a paint (Finecure RM-64, manufactured by sanyo chemical industry co., ltd.) and an optical pattern was embossed on the film surface containing the paint, followed by curing the paint, thereby producing a target relief-forming film. The total thickness of the relief-forming film was 125 μm and the haze value was 0.8%.

Fig. 8A is a plan view of a part of the produced uneven molded film viewed from the uneven surface side. Fig. 8B is a cross-sectional view of the concave-convex shaped film 8B-8B' of fig. 8A. The plurality of triangular recesses 74 having a length L of 80 μm, a width W of 17.3 μm, and a depth H of 10 μm are arranged at intervals of a width E (260 μm) in the X-axis direction. The pattern of the concave portions 74 is arranged at intervals of a width D (160 μm) in the Y-axis direction. In FIG. 8A, px is 340 μm and Py is 174 μm. The density of the concave portions 74 on the surface of the concave-convex shaping film was 2426/cm ² . The inclination angle θa in fig. 8B is about 60 °, and the inclination angle θb is 85 °. The occupied area ratio of the concave portion 74 when the film was viewed from the concave-convex surface side was 3.4%.

PREPARATION EXAMPLE 2

Production of polyester adhesive sheet

(1) Preparation of polyester resin A

A four-necked separable flask was equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a condenser tube equipped with a collector, 47g (molecular weight: 166) of terephthalic acid and 45g (molecular weight: 166) of isophthalic acid as carboxylic acid components, 115g (molecular weight: 566) of polytetramethylene glycol as alcohol components, 4g (molecular weight: 62) of ethylene glycol, 16g (molecular weight: 104) of neopentyl glycol and 23g (molecular weight: 144) of cyclohexanedimethanol, and 0.1g of tetrabutyl titanate as a catalyst were charged into the flask, and the flask was stirred while being filled with nitrogen gas, and the temperature was raised to 240℃and maintained at 240℃for 4 hours.

Then, the nitrogen inlet pipe and the condenser pipe with the collector were removed, and the mixture was changed to a vacuum pump, and the temperature was raised to 240℃and maintained at 240℃while stirring in a reduced pressure atmosphere (0.002 MPa). The reaction was continued for about 6 hours to obtain a polyester resin A. The polyester resin a is obtained by polymerizing the above monomer without using a solvent. The weight average molecular weight (Mw) of the polyester resin a measured by GPC was 59200. The prepared polyester resin a was dissolved in ethyl acetate and taken out of the flask to prepare a polyester resin a solution having a solid content concentration of 50 mass%.

(2) Preparation of adhesive composition solution

To 100 parts by mass of the solid content of the polyester resin a solution prepared above, 12 parts by mass of zirconium tetra acetylacetonate (trade name "organic ZC-162", manufactured by Matsumoto Fine Chemical corporation, "organic" is a registered trademark, hereinafter sometimes referred to as "ZC-162") as a crosslinking catalyst, 12 parts by mass of isocyanurate of hexamethylene diisocyanate (trade name "corona HX", manufactured by eastern corporation, "corona" is a registered trademark, hereinafter sometimes referred to as "corona 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 solid content concentration became 20% by mass, to prepare an adhesive composition solution.

(3) Production of adhesive sheet

An adhesive composition solution was applied to one surface of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRF38", manufactured by mitsubishi chemical corporation) after the silicone release treatment, to form an adhesive composition solution layer. The thickness of the adhesive composition solution layer was applied so that the thickness of the adhesive layer after the following step of treating at 40℃for 3 days became 7. Mu.m. The adhesive composition solution layer was dried at 150 ℃ for 1 minute and the solvent of the adhesive composition solution layer was removed, to obtain an adhesive composition layer. Next, an adhesive composition layer was attached to the release treated surface of a 38 μm polyethylene terephthalate (PET) film (trade name "MRE38", manufactured by mitsubishi chemical corporation) after the silicone release treatment, and the film was left to stand at 40 ℃ for 3 days. The adhesive layer was formed by treating the adhesive composition layer at 40 ℃ for 3 days and crosslinking the polyester resin a of the adhesive composition layer with a crosslinking agent. An adhesive sheet (laminate) having a laminate structure of PET film/adhesive layer/PET film was thus produced. The crosslinking reaction of the polyester resin a also partially occurs in the step of treating the adhesive composition solution layer at 150 ℃ for 1 minute, but the crosslinking reaction mostly occurs in the subsequent step of heating treatment at 40 ℃ for 3 days.

PREPARATION EXAMPLE 3

Preparation of acrylic adhesive sheet

(1) Preparation of adhesive composition solution

First, an acrylic polymer was prepared. In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet pipe, 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 (4 HBA), and 0.1 parts by mass of 2,2' -azobisisobutyronitrile as a polymerization initiator were added to the flask together with ethyl acetate so that the total amount of monomers became 50% by mass, nitrogen was introduced while stirring slowly, and after 1 hour of nitrogen substitution, the liquid temperature in the flask was kept around 58 ℃ for polymerization for 8 hours, to obtain an acrylic polymer. Here, after 2 hours from the start of the polymerization, ethyl acetate was added dropwise over 3 hours so that the solid content became 35 mass%. That is, an acrylic polymer solution having a solid content of 35 mass% of the acrylic polymer was obtained.

Next, an adhesive composition solution was prepared by adding 10 parts by mass of an ultraviolet-curable urethane acrylate resin a (weight average molecular weight Mw: 5500) and 1.0 part by mass of 2-hydroxy-4' - (2-hydroxyethoxy) -2-methylbenzophenone (trade name "Omnirad2959", manufactured by IGM japan contract) and 0.6 part by mass of 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane (trade name "tetra-C", manufactured by mitsubishi gas chemical Co., ltd.) as a crosslinking agent to 100 parts by mass of the polymer, based on the solid content.

(2) Production of adhesive sheet

An adhesive composition solution was applied to one surface of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRF38", manufactured by mitsubishi chemical corporation) after the silicone release treatment, to form an adhesive composition solution layer. At this time, 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) became 7 μm. The solvent of the adhesive composition solution layer was removed by drying the adhesive composition solution layer at 140 ℃ for 3 minutes, and the acrylic polymer was crosslinked with a crosslinking agent, to obtain an adhesive composition layer having a 1 st crosslinked structure. Next, an adhesive sheet having a laminate structure of a PET film/an adhesive composition layer/a PET film was produced by bonding an adhesive composition layer to a release treated surface of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRE38", manufactured by mitsubishi chemical corporation) after silicone release treatment.

PREPARATION EXAMPLE 4

(1) Preparation of polyester resin A

The procedure was carried out in the same manner as in production example 2.

(2) Preparation of adhesive composition solution

To 100 parts by mass of the solid content of the polyester resin A solution prepared above, 0.33 parts by mass of zirconium tetra acetylacetonate (trade name "organic ZC-162", manufactured by Matsumoto Fine Chemical Co., ltd.), 12 parts by mass of hexamethylene diisocyanate isocyanurate (trade name "Coronate HX", manufactured by Tosoh Co., ltd.) as a crosslinking agent, 20 parts by mass of acetylacetone as a catalyst reaction inhibitor were blended, and ethyl acetate was further added to give a solid content concentration of 20% by mass, to prepare an adhesive composition solution.

(3) Production of adhesive sheet

An adhesive composition solution was applied to one surface of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRF38", manufactured by mitsubishi chemical corporation) after the silicone release treatment, to form an adhesive composition solution layer. The thickness of the adhesive composition solution layer was applied so that the thickness of the dried adhesive layer became 7. Mu.m. The adhesive layer was obtained by drying the adhesive composition solution layer at 100 ℃ for 1 minute to remove the solvent of the adhesive composition solution layer. Next, an adhesive layer was attached to the release treated surface of a 38 μm polyethylene terephthalate (PET) film (trade name "MRE38", manufactured by mitsubishi chemical corporation) after the silicone release treatment. Thus, an adhesive sheet having a laminate structure of PET film/adhesive layer/PET film was produced. In the step of treating the adhesive composition solution layer at 100 ℃ for 1 minute, a reaction of crosslinking the polyester resin a with the crosslinking agent also occurs. In production example 4, the step of treating the adhesive composition solution of production example 4 with a crosslinking catalyst was not performed for 3 days at 40 ℃ after the drying step (aging step) as compared with production example 2, but since the adhesive composition solution of production example 4 contains about 5 times as much as the adhesive composition solution of production example 2, a reaction of crosslinking the polyester resin a with the crosslinking agent occurs in the step of treating the adhesive composition solution layer of production example 4 at 100 ℃ for 1 minute.

PREPARATION EXAMPLE 5

Preparation of acrylic adhesive sheet

(1) Preparation of adhesive composition solution

First, an acrylic polymer was prepared. In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet pipe, 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 (4 HBA), and 0.1 parts by mass of 2,2' -azobisisobutyronitrile as a polymerization initiator were added to the flask together with ethyl acetate so that the total amount of monomers became 50% by mass, nitrogen was introduced while stirring slowly, and after nitrogen substitution was performed for 1 hour, the liquid temperature in the flask was kept around 58 ℃ and polymerization was performed for 8 hours, to obtain an acrylic polymer. After 2 hours from the start of the polymerization, ethyl acetate was added dropwise over 3 hours to make the solid content 35% by mass. That is, an acrylic polymer solution having a solid content of 35 mass% of the acrylic polymer was obtained.

Next, an adhesive composition solution was prepared by mixing 0.15 parts by mass of trimethylolpropane/toluene diisocyanate trimer adduct (trade name Coronate L manufactured by easter corporation) and 0.075 parts by mass of dibenzoyl peroxide (Nyper BMT40 (SV)) as a crosslinking agent with 100 parts by mass of the polymer in the obtained acrylic polymer solution.

(2) Production of adhesive sheet

An adhesive composition solution was applied to one surface of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRF38", manufactured by mitsubishi chemical corporation) after the silicone release treatment, to form an adhesive composition solution layer. At this time, 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) became 5 μm. The solvent of the adhesive composition solution layer was removed by drying the adhesive composition solution layer at 150 ℃ for 3 minutes, and the acrylic polymer was crosslinked with a crosslinking agent, to obtain an adhesive composition layer. Next, an adhesive sheet having a laminate structure of a PET film/an adhesive composition layer/a PET film was produced by bonding an adhesive composition layer to a release treated surface of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRE38", manufactured by mitsubishi chemical corporation) after silicone release treatment.

Production example 6

(1) Preparation of polyester resin A

The procedure was carried out in the same manner as in production example 2.

(2) Preparation of adhesive composition solution

To 100 parts by mass of the solid content of the polyester resin a solution prepared above, 12 parts by mass of zirconium tetra acetylacetonate (trade name "organic ZC-162", manufactured by Matsumoto Fine Chemical corporation, "organic" is a registered trademark, hereinafter sometimes referred to as "ZC-162") as a crosslinking catalyst, and 12 parts by mass of isocyanurate of hexamethylene diisocyanate (trade name "corona HX", manufactured by eastern corporation, "corona" is a registered trademark, hereinafter sometimes referred to as "corona HX") as a crosslinking agent, and 20 parts by mass of acetylacetone as a catalyst reaction inhibitor were blended, and ethyl acetate was further added so that the solid content concentration became 20% by mass, to prepare an adhesive composition solution.

(3) Production of adhesive sheet

An adhesive composition solution was applied to one surface of a 38 μm thick polyethylene terephthalate (PET) film (trade name "MRF38", manufactured by mitsubishi chemical corporation) after the silicone release treatment, to form an adhesive composition solution layer. The thickness of the adhesive composition solution layer was applied so that the thickness of the dried adhesive layer became 7 μm. The adhesive layer was obtained by drying the adhesive composition solution layer at 100 ℃ for 3 minutes to remove the solvent of the adhesive composition solution layer. Next, an adhesive composition layer was attached to the release treated surface of a 38 μm polyethylene terephthalate (PET) film (trade name "MRE38", manufactured by mitsubishi chemical corporation) after the silicone release treatment. An adhesive sheet (laminate) having a laminate structure of PET film/adhesive layer/PET film was thus produced.

Example 1

The adhesive sheet obtained in production example 2 was peeled off one piece of the peeled PET film, the exposed surface of the adhesive layer was bonded to an acrylic resin film (thickness: 30 μm), and the other piece of the separator (PET film) was peeled off and bonded to the concave-convex shaped film of production example 1, and the autoclave treatment was performed at 50 ℃ and 0.5MPa for 15 minutes to obtain an optical laminate having a laminate structure of an acrylic resin film/adhesive layer/concave-convex shaped film.

Example 2

The adhesive sheet obtained in production example 3 was peeled off one piece of the peeled PET film, the exposed adhesive composition layer was bonded to an acrylic resin film (thickness: 20 μm), and the other piece of the separator (PET film) was peeled off and bonded to the concave-convex shaped film of production example 1 at a pressure of 0.03MPa, whereby a laminate having a laminate structure of an acrylic resin film/adhesive composition layer/concave-convex shaped film was obtained.

Then, the laminate was irradiated with ultraviolet light from the acrylic resin film side, and the ultraviolet curable resin in the adhesive composition layer was cured, thereby obtaining an optical laminate having a laminate structure of an acrylic resin film, an adhesive layer, and an uneven molding film. The ultraviolet irradiation was performed using an LED lamp (peak illuminance: 200mW/cm, manufactured by Quark Technology, inc.) ² Cumulative light quantity 500mJ/cm ² (wavelength 345 to 365 nm)), the illuminance of the ultraviolet light was measured using a UV Power Puck (manufactured by Fusion UV Systems JAPAN Co., ltd.).

Example 3

The adhesive sheet obtained in production example 4 was peeled off one piece of the peeled PET film, the exposed adhesive composition layer was bonded to an acrylic resin film (thickness: 30 μm), and the other piece of the separator (PET film) was peeled off and bonded to the concave-convex shaped film of production example 1, and the autoclave treatment was performed at 50 ℃ and 0.5MPa for 15 minutes to obtain an optical laminate having a laminate structure of an acrylic resin film/adhesive layer/concave-convex shaped film.

Comparative example 1

The adhesive sheet obtained in production example 5 was peeled off one piece of the peeled PET film, the exposed adhesive composition layer was bonded to an acrylic resin film (thickness: 20 μm), and the other piece of the separator (PET film) was peeled off and bonded to the concave-convex shaped film of production example 1 at a pressure of 0.05MPa, whereby an optical laminate having a laminated structure of the acrylic resin film/adhesive composition layer/concave-convex shaped film was obtained.

Comparative example 2

The adhesive sheet obtained in production example 6 was peeled off one piece of the peeled PET film, the exposed adhesive composition layer was bonded to an acrylic resin film (thickness: 30 μm), and the other piece of the separator (PET film) was peeled off and bonded to the concave-convex shaped film of production example 1, and the autoclave treatment was performed at 50 ℃ and 0.5MPa for 15 minutes to obtain an optical laminate having a laminate structure of an acrylic resin film/adhesive layer/concave-convex shaped film.

[ evaluation item ]

< light distribution Property >)

An optical laminate having a laminate structure of an acrylic resin film, an adhesive layer, and a concave-convex forming film was laminated on an acrylic plate having a thickness of 2mm via an adhesive layer, to prepare an evaluation sample. The concave-convex shaping film of the optical laminate and the acrylic plate are bonded together via an adhesive layer. As in the illumination device 200B of fig. 4B, a white LED (light source) is disposed so that light is emitted toward the side surface of the acrylic plate (light guide layer), and the 1 st inclined surface having the small inclination angle θa of the concave portion of the concave-convex shaping film is disposed closer to the light source (white LED) than the 2 nd inclined surface having the large inclination angle θb. The front luminance (unit: cd/m) of the light transmitted through the evaluation sample was measured by using a cone polarimeter (Conosope 070 omnibearing polar angle, manufactured by radio Co., ltd. -70 DEG to 70 DEG) ² ). Fig. 7 schematically shows a typical example of the measurement result. Based on the obtained results, the light distribution characteristics of the illumination device having the optical laminate were evaluated according to the following criteria.

O (OK): when the brightness of the main peak is set as 100%, the brightness of the polar angle of the main peak over +10 DEG is less than 65%

X (NG): when the luminance of the main peak is set to 100%, the luminance of the main peak having a polar angle of +10° or more is 65% or more

In the NG example of fig. 7, in addition to the main peak (for example, a peak having the maximum value of luminance at a polar angle of-10 ° to 10 °), a peak having a relatively large luminance (65% or more of the luminance of the main peak) is generated at a polar angle larger than the main peak. In the example of OK of fig. 7, there is no significant peak at a polar angle larger than the main peak (e.g., a peak having a maximum value of luminance at a polar angle of-10 ° to 10 °). For example, the luminance at a polar angle of +20° or more of the main peak is suppressed to 30% or less of the luminance of the main peak. The light distribution control of the example of OK is considered to be more excellent than that of the example of NG.

< evaluation of haze value >)

The haze value of the obtained adhesive sheet was measured by using a haze meter (device name "HZ-1", manufactured by SUGA tester co.) and using D65 light. The adhesive sheet was sandwiched between an acrylic resin film having a thickness of 30 μm and a cycloolefin film having a thickness of 60 μm, and the cycloolefin film was disposed on the light source side and measured.

< evaluation of gel fraction >

The adhesive composition (before curing the curable resin) was used to prepare about 0.1g of each adhesive sheet of examples 1 to 3 and comparative examples 1 to 2 (example 2 is an adhesive sheet having an adhesive layer after curing the curable resin), and the adhesive sheet was wrapped with a porous tetrafluoroethylene sheet (trade name "NTF1122", manufactured by Nidong electric Co., ltd.) having an average pore diameter of 0.2 μm, and then bound with kite strings, and the mass (referred to as "sample A") was measured (referred to as the mass (W2) before impregnation). The pre-dipping mass (W2) is the total mass of the adhesive composition, the porous tetrafluoroethylene sheet and the zither thread. The total mass of the porous tetrafluoroethylene sheet and the kite string (referred to as the bag mass (W1)) was separately measured.

Next, the specimen sample A1 was placed in a 50mL container filled with ethyl acetate, and allowed to stand at 23℃for 7 days. Then, the sample A1 (after ethyl acetate treatment) was taken out of the container, transferred to an aluminum cup, dried in a dryer at 130 ℃ for 2 hours to remove ethyl acetate, and then the mass of the sample A1 was measured (as a mass after dipping (W3)). Gel fraction was calculated according to the following formula.

Gel fraction (% (mass%) = (W3-W1) ×100/(W2-W1)

< evaluation of initial tensile modulus of adhesive composition >

From each of the adhesive sheets of examples 1 and 3 and comparative examples 1 and 2, test pieces having a width of 30mm and a length of 60mm were cut, and one piece of the peeled PET film was peeled off, and the exposed adhesive layer was formed into a cylindrical shape having a diameter of about 0.6mm, to prepare a sample for measurement.

The cylindrical measurement sample was set in a tensile compression tester (apparatus name "AGS-50NX", manufactured by Shimadzu corporation) at a temperature of 23℃and a measurement environment of 65% RH, and was drawn along a line at a drawing speed of 50 mm/min at a distance of 10mm between chucksThe axial extension of the cylinder was measured to determine the amount of change (mm) caused by the axial extension. Thus, in the obtained S-S (stress Strain, stress-stress) curve, the tensile Strain (. Epsilon.) at the point to be 2 ₁ =5% and ε ₂ When the corresponding tensile stress is σ1 and σ2, =10%), the initial tensile modulus E of the adhesive composition is set to ₀ Let E be ₀ ＝(σ ₂ －σ ₁ )/(ε ₂ －ε ₁ ). Wherein the tensile strain ε is calculated based on the distance between chucks.

ε＝(L ₁ －L ₀ )/L ₀

Or alternatively

ε(％)＝100×(L ₁ －L ₀ )/L ₀

Epsilon: tensile Strain (ratio or% of dimensionless)

L ₀ : initial inter-chuck distance (mm)

L ₁ : distance between chucks after stretching (mm)

The tensile stress σ is calculated based on the cross-sectional area of the test piece before stretching.

σ＝F/A

Sigma: tensile stress (MPa)

F: measuring load (N)

A: cross-sectional area (mm) of test piece before stretching ² )

For example 2, the initial tensile modulus of the adhesive after the curable resin was cured by irradiation of ultraviolet rays was evaluated. A sample piece having a width of 20mm and a length of 60mm was cut out from the adhesive sheet to obtain a sample for measurement. The amount of change (mm) in the sample caused by stretching in the longitudinal direction was measured, and the initial tensile modulus was evaluated.

TABLE 1

TABLE 2

	Example 1	Example 2	Example 3	Comparative example 1	Comparative example 2
						A[μm]	0.4	1	1.9	2.7	8.5
B[μm]	0	0	0	1	8.5
						C[μm]	10	10	9.4	7.4	8.5
(C-A)/C	0.96	0.9	0.8	0.64	0
						(C-A)/(C-B)	0.96	0.9	0.8	0.73	-
Light distribution characteristics	○	○	○	×	×
						Haze [%]	0.5	0.4	0.4	0.4	0.4
Gel fraction [%]	96.3	97	81.5	97	36.4
						Initial tensile modulus [ MPa ]]	2.34	2.8	1.4	0.19	0.53

The maximum value A of the height of the adhesive layer in the concave portion, the minimum value B of the height of the adhesive layer in the concave portion and the depth C of the concave portion are obtained from the measured length of the cross-sectional image of the optical laminate. The average value is obtained by measuring sectional images at a plurality of positions selected arbitrarily. The depth C of the recess may be different depending on the sample, and may be different depending on the cutting position (cutting position) of the cross section.

The optical laminates of examples 1 to 3 each satisfy the formulas (I) and (II). The lighting devices having the optical layered bodies of examples 1 to 3 were excellent in light distribution control. In contrast, the optical laminates of comparative examples 1 and 2 did not satisfy the formulas (I) and (II). From the standpoint of light distribution control, the lighting devices having the optical layered bodies of comparative examples 1 and 2 were inferior to those of examples 1 to 3.

The adhesive layer of the optical laminate of comparative example 2 is formed without performing a step (aging step) of treating at 40 ℃ for 3 days after the step (drying step) of removing the solvent of the adhesive composition solution layer, as compared with the adhesive layer of the optical laminate of example 1. Comparative example 2 is the same as the type and amount of the crosslinking catalyst used in example 1. In example 1, the crosslinking reaction of the polyester resin a also partially occurred in the drying step, but most of the crosslinking reaction of the polyester resin a occurred in the step of performing the treatment at 40 ℃ for 3 days. In comparative example 2, since the step of treating at 40 ℃ for 3 days was not performed, it is considered that the crosslinking reaction of the polyester resin a did not sufficiently occur, and the obtained adhesive layer could not suppress the invasion into the concave portion of the concave-convex structure of the optical sheet. The adhesive layer of comparative example 2 also had a low gel fraction of less than 40%.

In example 3, the step of treating the polyester resin a with a crosslinking agent (aging step) was not performed for 3 days at 40 ℃ after the drying step, but since the adhesive composition solution used in example 3 contains about 5 times as much as the crosslinking catalyst of the adhesive composition solution used in example 1, it is considered that in example 3, the reaction of crosslinking the polyester resin a with the crosslinking agent occurred in the step of treating the adhesive composition solution layer at 100 ℃ for 1 minute, and the obtained adhesive layer can suppress the intrusion into the concave and convex structure of the optical sheet.

When an adhesive layer formed by crosslinking an adhesive composition containing a polyester resin, a crosslinking agent, and a crosslinking catalyst is used as the adhesive layer, for example, the polyester resin is preferably a copolymer of a polycarboxylic acid and a polyhydric alcohol, and contains 0.01 parts by mass or more of the crosslinking catalyst, and the crosslinking catalyst is preferably at least one selected from the group consisting of an organozirconium compound, an organoiron compound, and an organoaluminum compound, relative to 100 parts by mass of the polyester resin. The step of crosslinking the adhesive composition preferably includes a step (aging step) of performing a treatment at a temperature of 25 ℃ or higher and 80 ℃ or lower for 1 day or more, for example. The adhesive layer may be formed without performing the aging process. The adhesive layer preferably is formed of an adhesive composition containing a crosslinking catalyst in an amount of, for example, 0.2 parts by mass or more based on 100 parts by mass of the polyester resin.

The adhesive layer of the optical laminate of comparative example 1 is significantly different from the adhesive layer of the optical laminate of example 2 in that it does not contain a cured product of an ultraviolet-curable resin. It is known that when the adhesive layer is formed using an acrylic polymer, a cured product containing an ultraviolet curable resin is preferable. However, the present invention is not limited thereto, and, for example, by adjusting the composition of the acrylic polymer, the penetration into the concave portion of the concave-convex structure of the optical sheet can be suppressed even in the case of the adhesive layer containing no cured product of the ultraviolet-curable resin.

Industrial applicability

The optical laminate of the present invention can be widely used for optical devices such as display devices and illumination devices.

Claims

1. An optical laminate, comprising:

a 1 st optical sheet having a 1 st main surface and a 2 nd main surface opposite to the 1 st main surface, the 1 st main surface having a concave-convex structure; and

an adhesive layer disposed on the 1 st main surface side of the 1 st optical sheet,

the concave-convex structure includes a plurality of concave portions, and flat portions between adjacent concave portions among the plurality of concave portions,

the adhesive layer is in contact with the flat portion,

2. The optical stack according to claim 1, wherein,

3. The optical laminate according to claim 1 or 2, wherein,

when the 1 st optical sheet is viewed from the normal direction of the 1 st main surface, the ratio of the area of the plurality of concave portions to the area of the 1 st optical sheet is 0.3% or more and 80% or less.

4. The optical laminate according to any one of claim 1 to 3, wherein,

the plurality of concave portions have a triangular, quadrangular, or at least a part thereof having a curved shape in cross section.

5. The optical laminate according to any one of claims 1 to 4, having a haze value of 5.0% or less.

6. The optical laminate according to any one of claims 1 to 5, wherein,

the adhesive layer is any one of the following adhesive layers Aa, ab and Ac,

after curing the curable resin of the adhesive composition, the adhesive layer Ab has an initial tensile modulus at 23 ℃ of 1.00MPa or more;

the gel fraction of the adhesive layer Ac after being kept at a temperature of 85 ℃ and a relative humidity of 85% for 300 hours is more than 40%,

7. The optical laminate according to any one of claims 1 to 6, wherein,

the adhesive layer contains at least one of the following polymers (1) to (3):

(2) Copolymers of carboxyl-containing acrylic monomers with at least one other monomer that does not include a nitrogen-containing (meth) acrylic monomer;

(3) Polyester-based polymers.

8. The optical laminate according to any one of claims 1 to 7, further comprising a 2 nd optical sheet, wherein the 2 nd optical sheet is disposed on a side of the adhesive layer opposite to the 1 st optical sheet side.

9. The optical laminate according to any one of claims 1 to 8, wherein,

in each of the plurality of concave portions, a height of the adhesive layer on the 1 st inclined surface of the concave portion is a maximum value of heights of the adhesive layers existing in the concave portion.

10. The optical stack according to claim 9, wherein,

the inclination angle thetaa of the 1 st inclined surface is smaller than the inclination angle thetab of the 2 nd inclined surface.

11. An optical device comprising the optical laminate according to any one of claims 1 to 10.