JP2022053201A - Optical laminate - Google Patents

Abstract

To provide an optical laminate having high luminance, suppressed in luminance unevenness, excellent in strength as an integral object, and suppressed in light leakage under a high humid environment.SOLUTION: An optical laminate comprises: a light guide plate; an adhesion layer arranged on the light guide plate in a dot pattern in plain view; a low-refractive index reinforcement part arranged in both end parts in the light guide direction of the light guide plate and including a low-refractive index part; and an optical member laminated on the light guide plate via the adhesion layer and the low-refractive index reinforcement part. The adhesion layer forms a pattern in which a density of dots becomes larger from an incident light side of the light guide plate in the light guide direction. In a region in which the adhesion layer between the light guide plate and the optical member, and the low-refractive index reinforcement part are not arranged, a low-refractive index layer is arranged so as to come in contact with at least one of a surface at the adhesion layer side of the light guide plate and a surface at the adhesion layer side of the optical member. The refractive index of the low-refractive index part and the low-refractive index layer is 1.30 or less.SELECTED DRAWING: Figure 1A

Description

The present invention relates to an optical laminate.

When laminating a light guide plate and peripheral optical members (for example, a reflector, a diffuser plate, a prism sheet, a light extraction film) in an optical device (for example, an image display device, a lighting device) that extracts light using a light guide plate. , A technique of laminating via a low index of refraction layer or a patterned (ie, having an air portion) adhesive layer is known. According to such a technique, it is reported that by utilizing the air portion of the low refractive index layer or the adhesive layer, the light utilization efficiency is higher than that in the case of simply laminating with only the adhesive. However, according to such a technique, there is a problem that the strength of the laminated body of the light guide plate and the peripheral optical member as an integral body is insufficient.

The present applicant has developed an optical laminate that can solve such a problem (Patent Document 1). The optical laminate has a light guide plate and an optical member laminated on the light guide plate via an adhesive layer, the adhesive layer is formed in a plan view dot pattern, and the density of the dots is the said. It has a gradient that increases from the light entrance side of the light guide plate along the light guide direction, and low refractive index reinforcing portions are provided at both ends of the light guide plate along the light guide direction. By providing the adhesive layer having the predetermined dot pattern and the low refractive index reinforcing portion, it is possible to realize an optical laminate having high luminance, suppression of luminance unevenness, and excellent strength as an integral body. can.

International Publication No. 2020/116045

However, the optical laminate of Patent Document 1 may leak light in a high humidity environment.

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is high brightness, suppression of uneven brightness, excellent strength as an integral body, and light leakage in a high humidity environment. It is an object of the present invention to provide an optical laminate in which the above is suppressed.

The optical laminate according to the embodiment of the present invention has a light guide plate, an adhesive layer arranged on the light guide plate in a plan view dot pattern, and low refractive index arranged at both ends of the light guide plate along the light guide direction. It has a low refractive index reinforcing portion including a rate portion, and an optical member laminated on the light guide plate via the adhesive layer and the low refractive index reinforcing portion. The adhesive layer forms a pattern in which the density of dots increases from the light entrance side of the light guide plate along the light guide direction. In the region where the adhesive layer and the low refractive index reinforcing portion between the light guide plate and the optical member are not arranged, the surface of the light guide plate on the adhesive layer side and the surface of the optical member on the adhesive layer side. The low refractive index layer is arranged so as to be in contact with at least one of them. The refractive index of the low refractive index portion and the low refractive index layer is 1.30 or less.
In one embodiment, the low refractive index layer is arranged so as to be in contact with both the surface of the light guide plate on the adhesive layer side and the surface of the optical member on the adhesive layer side. In one embodiment, the low refractive index layer fills the entire region where the adhesive layer and the low refractive index reinforcing portion between the light guide plate and the optical member are not arranged.
In one embodiment, the refractive index of the low refractive index portion and the low refractive index layer is 1.25 or less.
In one embodiment, the low refractive index portion and the low refractive index layer are void layers formed by chemically binding fine pore particles to each other.
In one embodiment, the low refractive index reinforcing portion has a base material, a low refractive index portion formed on the base material, and a pressure-sensitive adhesive layer provided on both sides as an outermost layer.
In one embodiment, the total width of the low refractive index reinforcing portions is 10% or less of the width of the light guide plate.
In one embodiment, the total light transmittance of the low refractive index reinforcing portion is 85% or more.
In one embodiment, the optical laminate is further provided with a low refractive index reinforcing portion at an end of the light guide plate on the side opposite to the light entering side.

According to the present invention, in an optical laminate having a light guide plate and an optical member and having an adhesive layer of a plan view dot pattern having a gradient of dot density along the light guide direction of the light guide plate, the light guide plate is provided. A low refractive index reinforcing portion including a low refractive index portion is provided at both ends along the light guide direction, and the adhesive layer and the low refractive index reinforcing portion between the light guide plate and the optical member are arranged. A low refractive index layer is provided so as to be in contact with at least one of the surface of the light guide plate on the adhesive layer side and the surface of the optical member on the adhesive layer side, and the refraction of the low refractive index portion and the low refractive index layer is further provided. By setting the ratio to 1.30 or less, it is possible to realize an optical laminate having high brightness, suppression of uneven brightness, excellent strength as an integral body, and suppression of light leakage in a high humidity environment. can.

It is a schematic sectional drawing of the optical laminated body by one Embodiment of this invention. It is the schematic sectional drawing of the optical laminated body by another embodiment of this invention. It is the schematic sectional drawing of the optical laminated body by still another Embodiment of this invention. FIG. 3 is a schematic plan view showing a state in which the optical member of the optical laminate of FIG. 1A is removed. It is a schematic sectional drawing which shows an example of the low refractive index reinforcing part used in the optical laminated body by embodiment of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Overall Configuration of Optical Laminates FIG. 1A is a schematic cross-sectional view of an optical laminate according to one embodiment of the invention; FIG. 1B is a schematic cross-sectional view of an optical laminate according to another embodiment of the invention; FIG. 1C is a schematic cross-sectional view of an optical laminate according to still another embodiment of the present invention; FIG. 2 is a schematic plan view showing a state in which the optical member of the optical laminate of FIG. 1A is removed. The optical laminate 100 of FIG. 1A has a light guide plate 10, an adhesive layer 20 arranged on the light guide plate 10 in a plan view dot pattern, and a low refractive index arranged at both ends of the light guide plate 10 along the light guide direction. It has a reinforcing portion 40 and an optical member 30 laminated on the light guide plate 10 via an adhesive layer 20 and a low refractive index reinforcing portion 40. As shown in FIG. 2, the adhesive layer 20 forms a pattern in which the density of dots increases from the light entrance side of the light guide plate along the light guide direction (direction from the left side to the right side of the drawing). By providing the adhesive layer of the dot pattern having such a density gradient, total reflection by air can be utilized at the light entrance side end of the light guide plate having a large amount of light, and therefore, extremely good light in the light guide plate. Propagation is realized. As a result, the brightness can be increased and uneven brightness (the brightness is different between the portion near the incoming light side and the portion far from the incoming light side) can be remarkably suppressed. On the other hand, such an adhesive layer has a non-uniform adhesive strength (specifically, the adhesive strength on the incoming light side is small and the adhesive strength on the opposite side to the incoming light side is large), and as a result, the optical lamination is performed. The strength as an integral part of the body becomes insufficient. On the other hand, by providing the low refractive index reinforcing portion, sufficient strength as an integral body of the optical laminate can be realized. Further, the low refractive index reinforcing portion used in the embodiment of the present invention has the following advantages: (1) Since the refractive index of the reinforcing portion itself is low, the efficiency of light utilization is not reduced (as a result). It is possible to secure the strength of the optical laminate as an integral body (while maintaining high brightness and suppressing uneven brightness); (2) Since it can be formed into an elongated shape, the optical laminate is applied. The effect on the display area of the image display device can be minimized.

In the embodiment of the present invention, the light guide plate 10 is located in a region (that is, a gap portion in the optical laminate) in which the adhesive layer 20 and the low refractive index reinforcing portion 40 are not arranged between the light guide plate 10 and the optical member 30. The low refractive index layer 50 is arranged so as to be in contact with at least one of the surface on the adhesive layer 20 side and the surface on the adhesive layer 20 side of the optical member 30. In one embodiment, the low refractive index layer 50 is arranged so as to be in contact with both the surface of the light guide plate 10 on the adhesive layer 20 side and the surface of the optical member 30 on the adhesive layer 20 side. In the example shown in FIG. 1A, the low refractive index layer 50 is the entire region (that is, in the optical laminate) in which the adhesive layer 20 between the light guide plate 10 and the optical member 30 and the low refractive index reinforcing portion 40 are not arranged. It fills the entire gap). By providing such a low refractive index layer, light leakage in a high humidity environment can be suppressed. More details are as follows. Applicants have a light guide plate, an adhesive layer arranged on the light guide plate in a pattern such that the density of dots increases from the light entrance side of the light guide plate along the light guide direction, and along the light guide direction of the light guide plate. We have developed an optical laminate having low refractive index reinforcing portions arranged at both ends and an optical member laminated on a light guide plate via an adhesive layer and a low refractive index reinforcing portion. Such an optical laminate has high luminance, suppresses luminance unevenness, and has excellent strength as an integral body. On the other hand, the present inventors have discovered a new problem that light leakage may occur in such an optical laminate in a high humidity environment, and the light leakage is a light guide plate in a high humidity environment. It has been found that this is caused by dew condensation that occurs in the region (void portion) where the adhesive layer and the low refractive index reinforcing portion between the optical member and the optical member are not arranged. Furthermore, as a result of diligent studies on the relationship between dew condensation and light leakage, the present inventors have provided a low refractive index layer in the void portion, so that dew condensation is maintained while maintaining the excellent characteristics of the optical laminate by the present applicant. We have found that light leakage due to generation can be suppressed, and have completed the present invention. That is, by arranging the low refractive index layer in the void portion as shown in FIGS. 1A to 1C, even if dew condensation occurs, light leakage from the surface of the optical member 30 on the side opposite to the surface on the adhesive layer 20 side is suppressed. can do. Further, as shown in FIG. 1A, when the low refractive index layer fills the void portion, the void portion is substantially eliminated, so that dew condensation can be remarkably suppressed, and as a result, light leakage can be remarkably suppressed. In addition, by arranging the low refractive index layer in the void portion, the difference in the refractive index from the void portion (air portion, refractive index 1.00) can be reduced. As a result, since the light utilization efficiency is not substantially lowered, it is possible to maintain the excellent characteristics of the optical laminate, that is, the brightness is maintained high and the brightness unevenness is suppressed. In addition, the following advantages can also be obtained. When the optical laminate is pressed, the presence of a gap may cause the light guide plate and the optical member to come into contact with each other, resulting in light leakage due to the contact. By arranging the low refractive index layer in the void portion, the contact can be avoided, so that light leakage due to such a mechanism can be suppressed.

The low refractive index layer 50 may be arranged so as to be in contact with both the surface of the light guide plate on the adhesive layer side and the surface of the optical member on the adhesive layer side, or may fill the void portion as shown in FIG. 1A. It may be arranged so as to be in contact with only the surface of the optical member 30 on the adhesive layer 20 side as shown in FIG. 1B, and may be arranged so as to be in contact with only the surface of the light guide plate 10 on the adhesive layer 20 side as shown in FIG. 1C. It may be arranged in. In either configuration, dew condensation and / or contact between the light guide plate and the optical member can be suppressed, and as a result, light leakage can be suppressed. Preferably, it is the configuration of FIG. 1A. This is because it has an effect of suppressing dew condensation itself (as a result, a light leakage suppressing effect).

The ratio of the thickness of the low refractive index layer 50 to the thickness of the void portion or the adhesive layer 20 is not particularly limited as long as light leakage can be suppressed.

Hereinafter, the constituent elements of the optical laminate will be specifically described.

B. Light guide plate The light guide plate 10 may be typically made of a resin (preferably transparent resin) film or plate-like material, or glass. Typical examples of such resins include thermoplastic resins and reactive resins (for example, ionizing radiation curable resins). Specific examples of the thermoplastic resin include (meth) acrylic resins such as polymethyl methacrylate (PMMA) and polyacrylonitrile, polyester resins such as polycarbonate (PC) resin and PET, and cellulose-based resins such as triacetyl cellulose (TAC). Examples thereof include resins, cyclic polyolefin resins, and styrene resins. Specific examples of the ionizing radiation curable resin include epoxy acrylate-based resin and urethane acrylate-based resin. These resins may be used alone or in combination of two or more.

The thickness of the light guide plate can be, for example, 100 μm to 100 mm. The thickness of the light guide plate is preferably 50 mm or less, more preferably 30 mm or less, and further preferably 10 mm or less.

The refractive index of the light guide plate is preferably 1.47 or more, more preferably 1.47 to 1.60, and further preferably 1.47 to 1.55. The difference between the refractive index of the light guide plate and the refractive index of the low refractive index layer of the low refractive index reinforcing portion is preferably 0.22 or more, more preferably 0.22 to 0.40, and further preferably 0. It is .25 to 0.35. The refractive index of the light guide plate can be adjusted by appropriately selecting the constituent material of the light guide plate.

C. Adhesive layer As described above, the adhesive layer 20 is formed of a dot pattern in a plan view, and has a gradient such that the density of dots increases from the light entrance side of the light guide plate along the light guide direction. With such a configuration, total reflection by air can be utilized at the light entrance side end portion of the light guide plate having a large amount of light, and therefore, extremely good light propagation is realized in the light guide plate. As a result, the brightness can be increased and uneven brightness (the brightness is different between the portion near the incoming light side and the portion far from the incoming light side) can be remarkably suppressed. The gradient of the dot density may change continuously along the light guide direction as shown in FIG. 2, or may change stepwise for each predetermined region along the light guide direction. For example, the dot density (average) in the region from the end on the light entering side to 10% in the length direction of the light guide plate is preferably 0% to 50%, and the light guide plate is from the end opposite to the light entrance side. The dot density (average) of the region up to 10% in the length direction is preferably 50% to 100%.

The adhesive layer may be composed of an adhesive or an adhesive. Preferably, the adhesive layer is composed of an adhesive. This is because pattern formation is easy. By using an adhesive, pattern formation can be performed by inkjet, printing, or the like. As the adhesive, any suitable adhesive can be used. Preferably, it is an active energy ray (for example, ultraviolet light, visible light) curable adhesive. Specific examples of the active energy ray-curable adhesive include acrylic adhesives, epoxy adhesives, vinyl adhesives, thiol adhesives, urethane adhesives, and silicone adhesives. The active energy ray-curable adhesive and the thermosetting adhesive may be used in combination. Examples of the pressure-sensitive adhesive include a pressure-sensitive adhesive having a high elastic modulus.

The thickness of the adhesive layer may be, for example, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, or 100 μm or more, and may be 1000 μm or less, 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, or 500 μm or less.

D. Optical member Examples of the optical member 30 include any suitable optical member that can be laminated with the light guide plate. Specific examples of the optical member include a reflector, a diffuser, a prism sheet, a polarizing plate, a retardation film, a conductive film, a substrate, an image display cell, or an image display panel.

E. Low refractive index reinforcement part E-1. Arrangement and overall configuration of the low refractive index reinforcing portion The low refractive index reinforcing portion 40 is provided at both ends of the light guide plate along the light guide direction as described above. Any suitable shape can be adopted as the plan view shape of the low refractive index reinforcing portion 40. Specifically, the low refractive index reinforcing portion may be formed continuously or intermittently along the light guide direction of the light guide plate as shown in FIG. When the low refractive index reinforcing portion is continuously formed, the low refractive index reinforcing portion may be, for example, an elongated rectangular shape as shown in FIG. 2, a tapered shape, or a trapezoidal shape. May be. When the low refractive index reinforcing portion has a tapered shape, the low refractive index reinforcing portion may have a shape that narrows toward the incoming light side or a shape that narrows toward the opposite side to the incoming light side. good. When the low index of refraction reinforcement is intermittently formed, the low index of refraction reinforcement may be, for example, rectangular, dot, or any other shape (eg, triangle, square). , Polygon, semi-circular). The length of the low refractive index reinforcing portion (that is, the length along the light guide direction) is preferably 50% or more, more preferably 60% or more, respectively, with respect to the total length of the light guide plate in the light guide direction. It is more preferably 70% or more, and particularly preferably 80% or more. The upper limit of the length of the low refractive index reinforcing portion is 100% with respect to the total length of the light guide plate in the light guide direction. That is, the low refractive index reinforcing portion may be provided over the entire light guide direction of the light guide plate. If the length is within such a range, a sufficient reinforcing effect (that is, the strength of the optical laminate as an integral body) can be realized. When the low refractive index reinforcing portion is intermittently formed, the length of the low refractive index reinforcing portion is the sum of the respective lengths. Further, the lengths of the low refractive index reinforcing portions may be the same or different. The width of the low refractive index reinforcing portion (that is, the length along the direction orthogonal to the light guide direction) is preferably 5% or less with respect to the width of the light guide plate, respectively. The total width of the low refractive index reinforcing portions is preferably 10% or less, more preferably 9% or less with respect to the width of the light guide plate. On the other hand, the total width of the low refractive index reinforcing portions may be, for example, 1% or more. When the width is within such a range, the strength of the optical laminate as an integral body can be ensured without adversely affecting the display area of the image display device to which the optical laminate is applied. The total light transmittance of the low refractive index reinforcing portion is preferably 85% or more, more preferably 90% or more. When the total light transmittance is within such a range, the strength of the optical laminate as an integral body can be ensured without adversely affecting the display area of the image display device to which the optical laminate is applied.

The low refractive index reinforcing portions may be provided at both ends of the light guide plate along the light guide direction, or may be provided inside at a certain distance from both ends. Preferably, the low refractive index reinforcing portion is provided at both ends or in the vicinity thereof along the light guide direction of the light guide plate. With such a configuration, the influence on the display area can be minimized.

When the low refractive index reinforcing portion is continuously formed, the low refractive index reinforcing portion may be provided at the center of the light guide plate in the light guide direction, and the low refractive index reinforcing portion may be provided at a biased position (for example, the incoming light side, the incoming light side). It may be provided on the opposite side). When the low refractive index reinforcing portions are formed intermittently, the respective arrangement densities may be uniform over the entire light guide direction or may change along the light guide direction.

As described above, the low refractive index reinforcing portions may be provided at both ends of the light guide plate along the light guide direction. Therefore, the low refractive index reinforcing portion may be provided at any appropriate position other than the above-mentioned position. In one embodiment, the low refractive index reinforcing portion may be further provided at the end portion of the light guide plate on the side opposite to the light entering side. With such a configuration, a further reinforcing effect can be obtained.

FIG. 3 is a schematic cross-sectional view showing an example of a low refractive index reinforcing portion. The low refractive index reinforcing portion 40 has a base material 41, a low refractive index portion 42 formed on the base material 41, and adhesive layers 43 and 44 provided as outermost layers on both sides. That is, the low refractive index reinforcing portion is configured as a double-sided tape, and the light guide plate and the optical member are bonded to each other by the adhesive layers on both sides. As is clear from the drawings, the low refractive index section 42 is substantially a low refractive index layer, but in the present specification, it is referred to as a low refractive index section in order to easily distinguish it from the low refractive index layer 50. Refer to.

E-2. Base material The base material 41 can be typically composed of a film or a plate-like material of a resin (preferably a transparent resin). Typical examples of such resins include thermoplastic resins and reactive resins (for example, ionizing radiation curable resins). Specific examples of the thermoplastic resin include (meth) acrylic resins such as polymethyl methacrylate (PMMA) and polyacrylonitrile, polyester resins such as polycarbonate (PC) resin and PET, and cellulose-based resins such as triacetyl cellulose (TAC). Examples thereof include resins, cyclic polyolefin resins, and styrene resins. Specific examples of the ionizing radiation curable resin include epoxy acrylate-based resin and urethane acrylate-based resin. These resins may be used alone or in combination of two or more.

The thickness of the base material is, for example, 10 μm to 100 μm, preferably 10 μm to 50 μm.

The refractive index of the substrate is preferably 1.47 or more, more preferably 1.47 to 1.60, and even more preferably 1.47 to 1.55. Within such a range, the light can be guided to the image display cell without adversely affecting the light extracted from the light guide plate.

E-3. Low refractive index portion The low refractive index portion typically has a void inside. The porosity of the low refractive index portion is typically 50% by volume or more, preferably 70% by volume or more, and more preferably 80% by volume or more. On the other hand, the porosity is, for example, 90% by volume or less, preferably 85% by volume or less. When the porosity is within the above range, the refractive index of the low refractive index portion can be set within an appropriate range. The porosity is a value obtained by calculating the porosity from the value of the refractive index measured by the ellipsometer from the Lorentz-Lorenz's formula (Lorentz-Lorenz's formula).

The refractive index of the low refractive index portion is preferably 1.25 or less, more preferably 1.20 or less, and further preferably 1.15 or less. The lower limit of the refractive index can be, for example, 1.01. Within such a range, it is possible to realize extremely excellent light utilization efficiency in the laminated structure of the light guide plate and the optical member obtained through the low refractive index reinforcing portion. Refractive index refers to the refractive index measured at a wavelength of 550 nm unless otherwise specified. The refractive index is a value measured by the method described in "(I) Refractive index of the low refractive index portion of the low refractive index layer and the low refractive index reinforcing portion" of the following Example.

Any suitable configuration can be adopted for the low refractive index portion as long as it has the above-mentioned desired porosity and refractive index. The low refractive index portion may be preferably formed by coating, printing or the like. As the material constituting the low refractive index portion, for example, the materials described in International Publication No. 2004/113966, Japanese Patent Application Laid-Open No. 2013-254183, and Japanese Patent Application Laid-Open No. 2012-189802 can be adopted. Specifically, for example, silica-based compounds; hydrolyzable silanes and / or silsesquioxane, and partial hydrolysates and dehydration condensates thereof; organic polymers; silicon compounds containing silanol groups; silicates. Active silica obtained by contact with an acid or ion exchange resin; polymerizable monomer (eg, (meth) acrylic monomer, and styrene monomer); curable resin (eg, (meth) acrylic resin, fluorine-containing resin). , And urethane resin); and combinations thereof. The low refractive index portion can be formed by applying or printing a solution or dispersion of such a material.

The size of the void (hole) in the low refractive index portion refers to the diameter of the major axis among the diameter of the major axis and the diameter of the minor axis of the void (hole). The size of the voids (pores) is, for example, 2 nm to 500 nm. The size of the voids (pores) is, for example, 2 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and further preferably 20 nm or more. On the other hand, the size of the void (pore) is, for example, 500 nm or less, preferably 200 nm or less, and more preferably 100 nm or less. The size range of the voids (pores) is, for example, 2 nm to 500 nm, preferably 5 nm to 500 nm, more preferably 10 nm to 200 nm, and even more preferably 20 nm to 100 nm. The size of the void (hole) can be adjusted to a desired size according to the purpose, application, and the like. The size of the voids (pores) can be quantified by the BET test method.

The size of the voids (pores) can be quantified by the BET test method. Specifically, 0.1 g of a sample (formed void layer) was put into the capillary of a specific surface area measuring device (manufactured by Micromeritic Co., Ltd .: ASAP2020), and then dried under reduced pressure at room temperature for 24 hours to allow voids. Degas the gas in the structure. Then, by adsorbing nitrogen gas to the sample, an adsorption isotherm is drawn and the pore distribution is obtained. Thereby, the void size can be evaluated.

The haze of the low refractive index portion is, for example, less than 5%, preferably less than 3%. On the other hand, the haze is, for example, 0.1% or more, preferably 0.2% or more. The range of haze is, for example, 0.1% or more and less than 5%, preferably 0.2% or more and less than 3%. The haze can be measured by, for example, the following method. The haze is an index of transparency of the low refractive index portion.
The void layer (low refractive index portion) is cut into a size of 50 mm × 50 mm and set in a haze meter (manufactured by Murakami Color Technology Research Institute: HM-150) to measure haze. The haze value is calculated from the following formula.
Haze (%) = [Diffusion transmittance (%) / Total light transmittance (%)] x 100 (%)

Examples of the low refractive index portion having voids inside include a low refractive index portion having a porous layer and / or an air layer in at least a part thereof. The porous layer typically includes airgel and / or particles (eg, hollow fine particles and / or porous particles). The low refractive index portion may be preferably a nanoporous layer (specifically, a porous layer having a diameter of 90% or more of micropores in the range of ^10-1 nm to ¹⁰³ nm).

Any suitable particles may be adopted as the particles. The particles are typically composed of silica-based compounds. The shape of the particles includes, for example, spherical, plate-like, needle-like, string-like, and grape tuft-like. As the string-shaped particles, for example, a particle in which a plurality of particles having a spherical, plate-like, or needle-like shape are connected in a bead shape, and a staple-like particle (for example, Japanese Patent Application Laid-Open No. 2001-188104) are described. Short fibrous particles), and combinations thereof. The string-shaped particles may be linear or branched. Examples of the tufted particles of grapes include those in which a plurality of spherical, plate-shaped, and needle-shaped particles are aggregated to form a tuft of grape. The shape of the particles can be confirmed, for example, by observing with a transmission electron microscope.

The thickness of the low refractive index portion is preferably 0.2 μm to 5 μm, and more preferably 0.3 μm to 3 μm. If the thickness of the low refractive index portion is within such a range, the damage prevention effect becomes remarkable. Further, the desired thickness ratio can be easily realized.

Hereinafter, an example of a specific configuration of the low refractive index portion will be described. The low refractive index portion of the present embodiment is composed of one or a plurality of types of structural units that form a fine void structure, and the structural units are chemically bonded to each other via catalytic action. Examples of the shape of the structural unit include a particle shape, a fibrous shape, a rod shape, and a flat plate shape. The structural unit may have only one shape, or may have a combination of two or more shapes. In the following, a case where the low refractive index portion is mainly a void layer of a porous body in which the fine pore particles are chemically bonded to each other will be described.

Such a void layer can be formed, for example, by chemically bonding fine pore particles to each other in the void layer forming step. In the embodiment of the present invention, the shape of the "particle" (for example, the fine pore particles) is not particularly limited, and may be spherical or another shape, for example. Further, in the embodiment of the present invention, the fine pore particles may be, for example, solgel beaded particles, nanoparticles (hollow nanosilica / nanoparticles), nanofibers and the like. The micropore particles typically contain inorganic substances. Specific examples of the inorganic substance include silicon (Si), magnesium (Mg), aluminum (Al), titanium (Ti), zinc (Zn), and zirconium (Zr). These may be used alone or in combination of two or more. In one embodiment, the micropore particles are, for example, micropore particles of a silicon compound, and the porous body also includes, for example, a silicone porous body (silica and / or a porous body containing silsesquioxane as a constituent unit). ). The fine pore particles of the silicon compound include, for example, a pulverized body of a gel-like silica compound. Further, as another form of the low refractive index portion having a porous layer and / or an air layer at least in a part thereof, for example, it is made of a fibrous substance such as nanofibers, and the fibrous substances are entangled to form voids. There is a layered void layer. The method for producing such a void layer is not particularly limited, and is the same as, for example, in the case of a porous void layer in which the fine pore particles are chemically bonded to each other. Still another form includes a void layer using hollow nanoparticles and nanoclay, and a void layer formed by using hollow nanoballoons and magnesium fluoride. The void layer may be a void layer composed of a single constituent substance, or may be a void layer composed of a plurality of constituent substances. The void layer may be composed of the single above-mentioned form, or may be composed of a plurality of the above-mentioned forms.

In the present embodiment, the porous structure of the porous body can be, for example, a continuous foam structure having a continuous pore structure. The continuous foam structure means that, for example, in the above-mentioned silicone porous body, the pore structures are three-dimensionally connected, and it can be said that the internal voids of the pore structure are continuous. Since the porous body has a continuous foam structure, it is possible to increase the porosity. However, when using single-foam particles (particles having individual pore structures) such as hollow silica, a continuous-foam structure cannot be formed. On the other hand, for example, when silica sol particles (crushed product of gel-like silicon compound forming a sol) are used, the coating film (crushed product of gel-like silicon compound) is included because the particles have a three-dimensional dendritic structure. The dendritic particles settle and deposit in the sol coating film), so that a continuous foam structure can be easily formed. The low refractive index portion more preferably has a monolithic structure in which the continuous foam structure includes a plurality of pore distributions. The monolith structure means, for example, a hierarchical structure including a structure in which nano-sized fine voids are present and a continuous bubble structure in which the nano-voids are aggregated. When forming a monolith structure, for example, it is possible to impart a high porosity to coarse continuous bubble voids while imparting film strength to fine voids, and to achieve both film strength and high porosity. Such a monolith structure can be preferably formed by controlling the pore distribution of the void structure formed in the gel (gel-like silicon compound) before pulverizing into silica sol particles. Further, for example, when the gelled silicon compound is pulverized, a monolith structure can be formed by controlling the particle size distribution of the silica sol particles after pulverization to a desired size.

The low refractive index portion contains, for example, a pulverized product of a gel-like compound as described above, and the pulverized products are chemically bonded to each other. The form of the chemical bond (chemical bond) between the pulverized substances in the low refractive index portion is not particularly limited, and examples thereof include a crosslink bond, a covalent bond, and a hydrogen bond.

The volume average particle size of the pulverized product in the low refractive index portion is, for example, 0.10 μm or more, preferably 0.20 μm or more, and more preferably 0.40 μm or more. On the other hand, the volume average particle diameter is, for example, 2.00 μm or less, preferably 1.50 μm or less, and more preferably 1.00 μm or less. The range of the volume average particle diameter is, for example, 0.10 μm to 2.00 μm, preferably 0.20 μm to 1.50 μm, and more preferably 0.40 μm to 1.00 μm. The particle size distribution can be measured by, for example, a particle size distribution evaluation device such as a dynamic light scattering method or a laser diffraction method, and an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The volume average particle size is an index of variation in the particle size of the pulverized product.

The type of gel compound is not particularly limited. Examples of the gel-like compound include a gel-like silicon compound.

Further, in the low refractive index portion (void layer), for example, it is preferable that the contained silicon atom is siloxane bonded. As a specific example, the proportion of unbonded silicon atoms (that is, residual silanol) in the total silicon atoms contained in the void layer is, for example, less than 50%, preferably 30% or less, and more preferably 15%. It is as follows.

Hereinafter, an example of a method for forming such a low refractive index portion will be described.

This method is typically a precursor forming step of forming a void structure which is a precursor of a low refractive index portion (void layer) on a resin film, and a crosslinking reaction inside the precursor after the precursor forming step. Includes a cross-linking reaction step, which causes The method is a step of preparing a containing liquid for producing a containing liquid containing fine pore particles (hereinafter, may be referred to as "fine pore particle-containing liquid" or simply "containing liquid"), and a drying method for drying the containing liquid. Further including a step, in the precursor forming step, the fine pore particles in the dried body are chemically bonded to each other to form a precursor. The containing liquid is not particularly limited, and is, for example, a suspension containing fine pore particles. In the following, a case where the fine pore particles are mainly pulverized gel-like compounds and the void layer is a porous body containing the pulverized gel-like compound (preferably a silicone porous body) will be described. However, the low refractive index portion can be similarly formed even when the fine pore particles are other than the pulverized product of the gel-like compound.

According to the above method, for example, a low refractive index portion (void layer) having a very low refractive index is formed. The reason is presumed as follows, for example. However, the guess does not limit the method of forming the low refractive index portion.

Since the crushed product is a crushed gel-like silicon compound, the three-dimensional structure of the gel-like silicon compound before crushing is dispersed in the three-dimensional basic structure. Further, in the above method, a crushed product of a gel-like silicon compound is applied onto a resin film to form a precursor having a porous structure based on a three-dimensional basic structure. That is, according to the above method, a new porous structure (three-dimensional basic structure) is formed by coating the pulverized material, which is different from the three-dimensional structure of the gel-like silicon compound. Therefore, in the finally obtained void layer, it is possible to realize a low refractive index that functions to the same extent as, for example, an air layer. Further, in the above method, the three-dimensional basic structure is immobilized because the crushed substances are chemically bonded to each other. Therefore, the finally obtained void layer can maintain sufficient strength and flexibility even though it has a structure having voids.

Details of the specific configuration and formation method of the low refractive index portion are described in, for example, International Publication No. 2019/151703. The description of this publication is incorporated herein by reference.

E-4. Adhesive Layer As the adhesive constituting the adhesive layer, any suitable adhesive may be used. Typical examples of the pressure-sensitive adhesive include an acrylic pressure-sensitive adhesive (acrylic pressure-sensitive adhesive composition). Since the acrylic pressure-sensitive adhesive composition is well known in the industry, detailed description thereof will be omitted. The thickness of the pressure-sensitive adhesive layer is, for example, 3 μm to 200 μm. The constituent materials and thicknesses of the pressure-sensitive adhesive layers 43 and 44 may be the same or different, respectively. When the pressure-sensitive adhesive layer is arranged adjacent to the low-refractive index portion, the pressure-sensitive adhesive layer is typically a low-refractive index portion when the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is in a normal state. It has a hardness that does not penetrate the voids. The storage elastic modulus of such a pressure-sensitive adhesive layer can be, for example, 1.3 × 10 ⁵ (Pa) to 1.0 × 10 ⁷ (Pa).

F. Low Refractive Index Layer The detailed configuration of the low refractive index layer 50 is basically as described in Section E-3 with respect to the low refractive index portion of the low refractive index reinforcing portion. Hereinafter, only the configuration characteristic of the low refractive index layer will be described.

When the low refractive index layer fills the void portion as shown in FIG. 1A, the thickness of the low refractive index layer is the same as the thickness of the adhesive layer, for example, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more. , Or 100 μm or more, and can be 1000 μm or less, 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, or 500 μm or less. Further, in the case of the configuration of FIG. 1B or 1C, the thickness of the low refractive index layer is not particularly limited as long as light leakage can be suppressed, but the lower limit thereof is preferably 0.6 μm or more, 0.75 μm or more, 0.80 μm or more. The upper limit thereof is preferably 3 μm or less and 2 μm or less.

The size of the voids (pores) in the low refractive index layer is preferably 400 nm or less, more preferably 300 nm or less, still more preferably 200 nm or less, and particularly preferably 100 nm or less. When the size of the voids (pores) in the low refractive index layer is within such a range, the infiltration of water can be satisfactorily suppressed, so that dew condensation can be satisfactorily suppressed. As a result, light leakage can be satisfactorily suppressed. The smaller the size of the void (pore), the more preferable, and the lower limit thereof can be, for example, 2 nm.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The measurement method for each characteristic is as follows.

(I) Refractive index of the low refractive index layer and the low refractive index portion of the low refractive index reinforcing portion After forming the low refractive index layer on the acrylic film, it is cut into a size of 50 mm × 50 mm, and this is cut into glass via an adhesive layer. It was affixed to the surface of a plate (thickness: 3 mm). The central portion (about 20 mm in diameter) of the back surface of the glass plate was painted with black magic to prepare a sample that does not reflect on the back surface of the glass plate. The above sample was set in an ellipsometer (manufactured by JA Woollam Japan: VASE), and the refractive index was measured under the conditions of a wavelength of 500 nm and an incident angle of 50 to 80 degrees.
(II) Luminance unevenness With respect to the optical laminates obtained in Examples and Comparative Examples, LED light was incident from the end of the light guide plate of the optical laminate, and the luminance unevenness was visually observed. It was evaluated according to the following criteria.
◯: Luminance (brightness) is uniform over the entire surface of the laminate ×: Light leakage is observed, the brightness is non-uniform, and / or there are few bright regions (III) Intensity Obtained in Examples and Comparative Examples. It was investigated whether or not the light guide plate and the prism film were peeled off when handling the optical laminate. It was evaluated according to the following criteria.
◯: Peeling did not occur and could be handled as an integral product without any problem. ×: Peeling occurred (IV) Light leakage The optical laminates obtained in Examples and Comparative Examples were heated to 20 ° C. and 98% RH. It was placed in a controlled constant temperature and humidity chamber for 1 hour for humidification treatment. LED light was incident on the optical laminate after the humidification treatment from the end of the light guide plate on the incoming light side, and the presence or absence of light leakage was visually inspected. It was evaluated according to the following criteria.
◯: Light leakage is observed and the brightness is non-uniform. ×: No light leakage is observed and the brightness is uniform.

[Production Example 1] Preparation of coating liquid for forming a low refractive index layer (1) Gelation of silicon compound Methyltrimethoxysilane (MTMS), which is a precursor of a silicon compound, is added to 2.2 g of dimethyl sulfoxide (DMSO). Mixture A was prepared by dissolving 0.95 g. MTMS is hydrolyzed by adding 0.5 g of a 0.01 mol / L oxalic acid aqueous solution to this mixture A and stirring at room temperature for 30 minutes to produce a mixture B containing tris (hydroxy) methylsilane. did.
After adding 0.38 g of 28% by weight aqueous ammonia and 0.2 g of pure water to 5.5 g of DMSO, the above mixture B was further added, and the mixture was stirred at room temperature for 15 minutes to obtain Tris ( Hydroxy) methylsilane was gelled to obtain a mixed solution C containing a gelled silicon compound.
(2) Aging treatment The mixed solution C containing the gelled silicon compound prepared as described above was incubated as it was at 40 ° C. for 20 hours for aging treatment.
(3) Crushing Treatment Next, the gelled silicon compound aged as described above was crushed into granules having a size of several mm to several cm using a spatula. Then, 40 g of isopropyl alcohol (IPA) was added to the mixture C, and the mixture was lightly stirred and then allowed to stand at room temperature for 6 hours to decant the solvent and catalyst in the gel. The same decantation treatment was carried out three times to replace the solvent, and a mixed solution D was obtained. Next, the gelled silicon compound in the mixed solution D was pulverized (high pressure medialess pulverization). For the pulverization treatment (high-pressure medialess pulverization), a homogenizer (manufactured by SMTE, trade name “UH-50”) was used, and 1.85 g of the gel compound and IPA in the mixed solution D were placed in a 5 cc screw bottle. After weighing 15 g, the mixture was pulverized for 2 minutes under the conditions of 50 W and 20 kHz.
By this pulverization treatment, the gelled silicon compound in the mixed solution D was pulverized, so that the mixed solution D'became a sol solution of the pulverized product. The volume average particle size showing the variation in the particle size of the pulverized material contained in the mixed solution D'was confirmed by a dynamic light scattering type nanotrack particle size analyzer (UPA-EX150 type manufactured by Nikkiso Co., Ltd.) and found to be 0.50 to. It was 0.70. Further, 0.062 g of a 1.5 wt% MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd .: trade name WPBG266) was added to 0.75 g of this sol solution (mixed solution D'). A 5% concentration MEK solution of bis (trimethoxysilyl) ethane was added at a ratio of 0.036 g to obtain a coating liquid A for forming a low refractive index layer.

[Production Example 2] Preparation of coating liquid for forming a low refractive index layer A sol liquid (mixed liquid D') was prepared in the same manner as in Production Example 1. To 0.75 g of this sol solution (mixed solution D'), 0.300 g of a 1.5 wt% MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd .: trade name WPBG266) was added to bis ( A 5% concentration MEK solution of trimethoxysilyl) ethane was added at a ratio of 0.090 g to obtain a coating liquid B for forming a low refractive index layer.

[Production Example 3] Preparation of Adhesive In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 90.7 parts of butyl acrylate, 6 parts of N-acryloyl morpholine, 3 parts of acrylic acid, Add 0.3 part of 2-hydroxybutyl acrylate and 0.1 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator together with 100 g of ethyl acetate, and introduce nitrogen gas with gentle stirring to replace nitrogen. After that, the liquid temperature in the flask was kept at around 55 ° C. and the polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. 0.2 parts of isocyanate cross-linking agent (Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd., trimethylolpropane tolylene diisocyanate adduct) and benzoyl peroxide (Japan) with respect to 100 parts of the solid content of the obtained acrylic polymer solution. An acrylic pressure-sensitive adhesive solution containing 0.3 part of Niper BMT manufactured by Yushi Co., Ltd. and 0.2 part of γ-glycidoxypropylmethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd .: KBM-403) was prepared. Next, the acrylic pressure-sensitive adhesive solution was applied to one side of a polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., thickness: 38 μm) treated with silicone, and the thickness of the pressure-sensitive adhesive layer after drying was predetermined. It was applied to a thickness and dried at 150 ° C. for 3 minutes to form an adhesive layer.

[Production Example 4] Preparation of a laminate with a double-sided adhesive layer (low refractive index reinforcing portion) The coating liquid A for forming a low refractive index layer prepared in Production Example 1 is applied to a base material (acrylic film) having a thickness of 30 μm. I worked on it. The wet thickness (thickness before drying) of the coating layer was about 27 μm. The coated layer was treated at a temperature of 100 ° C. for 1 minute and dried to form a low refractive index portion (thickness 0.9 μm) on the substrate. The refractive index of the obtained low refractive index portion was 1.18. Next, the pressure-sensitive adhesive layer formed in Production Example 3 on both sides of the laminate of the base material / low refractive index portion (thickness of the pressure-sensitive adhesive layer on the low-refractive index portion side is 10 μm, thickness of the pressure-sensitive adhesive layer on the base material side is 75 μm). Was arranged to prepare a laminate with a double-sided pressure-sensitive adhesive layer.

[Example 1]
The coating liquid A for forming a low refractive index layer prepared in Production Example 1 is coated and dried on a light guide plate (acrylic plate, thickness 400 μm, total length 85 mm in the light guide direction, width 60 mm, refractive index 1.49). , A low refractive index layer (refractive index 1.18, thickness 1 μm) was formed. Next, the low refractive index layer was cut with an iron rod (tip of 100 μm or less) to form a dot pattern. Further, both ends of the low refractive index layer along the light guide direction were removed with a spatula, and the laminate with the double-sided pressure-sensitive adhesive layer produced in Production Example 4 was attached to the removed portions to form a low refractive index reinforcing portion. Further, an epoxy adhesive (manufactured by Toagosei Corporation, product name "LCR0632") was printed by inkjet on the portion where the dot pattern was formed to form an adhesive layer having a pattern as shown in FIG. An optical laminate was produced by laminating a prism film on a light guide plate via a low refractive index reinforcing portion and an adhesive layer. In the obtained optical laminate, the thickness of the low refractive index reinforcing portion and the thickness of the adhesive layer were the same (115.9 μm). Further, the obtained optical laminate corresponds to the configuration shown in FIG. 1C. The obtained optical laminate was subjected to the evaluations (II) to (IV) above. The results are shown in Table 1.

[Example 2]
A low refractive index layer (refractive index 1.25, thickness 1 μm) was formed by using the low refractive index layer forming coating liquid B prepared in Production Example 2 instead of the low refractive index layer forming coating liquid A. An optical laminate was produced in the same manner as in Example 1 except for the above. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 3]
The laminate with the double-sided adhesive layer produced in Production Example 4 was bonded to both ends of the light guide plate along the light guide direction in the same manner as in Example 1 to form a low refractive index reinforcing portion. Further, the coating liquid A for forming the low refractive index layer A was applied and dried on the light guide plate to form a low refractive index layer having the same thickness (115.9 μm) as the low refractive index reinforcing portion. Then, an epoxy adhesive (manufactured by Toagosei Co., Ltd., product name "LCR0632") was printed on a dot pattern similar to that in Example 1 by inkjet to form an adhesive layer. The printed adhesive was infiltrated into the low refractive index layer to fill the voids in the low refractive index layer, and then a prism film was bonded over the prism film to obtain an optical laminate. The obtained optical laminate corresponds to the configuration of FIG. 1A. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
The laminate with the double-sided adhesive layer produced in Production Example 4 was bonded to both ends of the light guide plate along the light guide direction in the same manner as in Example 1 to form a low refractive index reinforcing portion. Further, an epoxy adhesive (manufactured by Toagosei Co., Ltd., product name "LCR0632") was printed on the light guide plate by inkjet in the same dot pattern as in Example 1 to form an adhesive layer. A prism film was bonded and integrated on the light guide plate via a low refractive index reinforcing portion and an adhesive layer. Next, a silicone-based OCR (manufactured by Asahi Kasei Wacker Silicone Co., Ltd., product name "LUMISIL 202UV", refractive index 1.42) was poured into the gap between the light guide plate and the prism film and cured to obtain an optical laminate. rice field. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
An optical laminate was produced in the same manner as in Example 1 except that the low refractive index reinforcing portion was not provided. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
The laminate with the double-sided adhesive layer produced in Production Example 4 was bonded to both ends of the light guide plate along the light guide direction in the same manner as in Example 1 to form a low refractive index reinforcing portion. Further, an epoxy adhesive (manufactured by Toagosei Co., Ltd., product name "LCR0632") was printed on the light guide plate by inkjet in the same dot pattern as in Example 1 to form an adhesive layer. A prism film was bonded and integrated on a light guide plate via a low refractive index reinforcing portion and an adhesive layer to obtain an optical laminate. That is, an optical laminate was produced in the same manner as in Example 1 except that the low refractive index layer was not provided. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 4]
An epoxy adhesive (manufactured by Toagosei Corporation, product name "LCR0632") was printed on the same light guide plate as in Example 1 by inkjet in the same dot pattern as in Example 1 to form an adhesive layer. A prism film was laminated on a light guide plate via an adhesive layer and integrated to obtain an optical laminate. That is, an optical laminate was produced in the same manner as in Example 1 except that neither the low refractive index reinforcing portion nor the low refractive index layer was provided. The obtained optical laminate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

As is clear from Table 1, according to the embodiment of the present invention, it is possible to obtain an optical laminate having high brightness, suppression of brightness unevenness, excellent strength as an integral body, and suppression of light leakage. can. In Comparative Example 1 in which the gap between the light guide plate and the optical member was filled with a high-refractive-index material, there were few bright regions and light leakage was observed. Comparative Example 2 in which the reinforcing portion was not provided had insufficient strength as an integral body. In Comparative Example 3 in which the low refractive index layer was not provided, light leakage was observed. In Comparative Example 4 in which the low refractive index layer and the reinforcing portion were not provided, the strength as an integral body was insufficient and light leakage was observed.

The optical laminate of the present invention can be suitably used for an optical device (for example, an image display device, a lighting device) that extracts light by using a light guide plate.

10 Light guide plate 20 Adhesive layer 30 Optical member 40 Low refractive index reinforcing part 41 Base material 42 Low refractive index part 50 Low refractive index layer 100 Optical laminated body 101 Optical laminated body 102 Optical laminated body

Claims (9)

Light guide plate and
An adhesive layer arranged in a plan view dot pattern on the light guide plate,
A low refractive index reinforcing portion including a low refractive index portion arranged at both ends along the light guide direction of the light guide plate, and a low refractive index reinforcing portion.
An optical member laminated on the light guide plate via the adhesive layer and the low refractive index reinforcing portion,
Have,
The adhesive layer forms a pattern in which the density of dots increases from the light entrance side of the light guide plate along the light guide direction.
At least the surface of the light guide plate on the adhesive layer side and the surface of the optical member on the adhesive layer side in the region where the adhesive layer and the low refractive index reinforcing portion are not arranged between the light guide plate and the optical member. The low refractive index layer is arranged so as to be in contact with one side,
The refractive index of the low refractive index portion and the low refractive index layer is 1.30 or less.
Optical laminate. The optical laminate according to claim 1, wherein the low refractive index layer is arranged so as to be in contact with both the surface of the light guide plate on the adhesive layer side and the surface of the optical member on the adhesive layer side. The optical laminate according to claim 2, wherein the low refractive index layer fills the entire region where the adhesive layer and the low refractive index reinforcing portion are not arranged between the light guide plate and the optical member. .. The optical laminate according to any one of claims 1 to 3, wherein the low refractive index portion and the low refractive index layer have a refractive index of 1.25 or less. The optical laminate according to any one of claims 1 to 4, wherein the low refractive index portion and the low refractive index layer are void layers formed by chemically bonding fine pore particles to each other. The optics according to any one of claims 1 to 5, wherein the low refractive index reinforcing portion has a base material, a low refractive index portion formed on the base material, and an adhesive layer provided as an outermost layer on both sides thereof. Laminated body. The optical laminate according to any one of claims 1 to 6, wherein the total width of the low refractive index reinforcing portions is 10% or less of the width of the light guide plate. The optical laminate according to any one of claims 1 to 7, wherein the total light transmittance of the low refractive index reinforcing portion is 85% or more. The optical laminate according to any one of claims 1 to 8, wherein a low refractive index reinforcing portion is further provided at an end portion of the light guide plate on the side opposite to the light entering side.

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