TW202212876A - Optical layered body - Google Patents

Abstract

Provided is an optical layered body which has high brightness, is suppressed in brightness unevenness, and has excellent strength as an integrated product, and in which light leakage under a high-humidity environment is suppressed. The optical layered body according to an embodiment of the present invention is provided with: a light guide plate; an adhesive layer disposed in the light guide plate in a dot pattern in a plan view; a low-refractive index reinforcing portion that includes a low-refractive index part and that is disposed in both end portions of the light guide plate along the light-guiding direction; and an optical member layered on the light guide plate with the adhesive layer and the low-refractive index reinforcing portion interposed therebetween. The adhesive layer has formed therein a pattern such that the density of dots increases from a light-entering side of the light guide plate along the light-guiding direction thereof. In an area which is between the light guide plate and the optical member and in which the adhesive layer and the low-refractive index reinforcing portion are not disposed, a low-refractive index layer is disposed so as to be in contact with an adhesive layer-side surface of the light guide plate and/or an adhesive layer-side surface of the optical member. The low-refractive index part and the low-refractive index layer each have a refractive index of 1.30 or less.

Description

Optical laminate

The present invention relates to an optical laminate.

Background technique

For optical devices (such as image display devices, lighting devices) that use a light guide plate to extract light, the following techniques are known. At the time, the lamination is performed through a low refractive index layer or a patterned (ie, having an air portion) adhesive layer. According to such a technique, it has been revealed that the use efficiency of light is higher by using the low-refractive index layer or the air portion of the adhesive layer, compared to the case of lamination using only an adhesive. However, according to such a technique, there is a problem that the strength of the integrated product of the laminated body of the light guide plate and the peripheral optical members is insufficient.

The present applicant has developed an optical layered body that can solve the above-mentioned problems (Patent Document 1). The optical laminate has a light guide plate and an optical member laminated on the light guide plate via a bonding layer, the bonding layer is formed in a plan view dot pattern, and the dot density increases along the light guiding direction from the light incident side of the light guide plate A low-refractive-index reinforcing part is arranged at both ends of the light guide plate along the light guide direction. By providing the adhesive layer and the low-refractive-index reinforcing portion having the above-described specific dot pattern, an optical laminate having high brightness, suppressed brightness unevenness, and excellent strength as a single body can be realized. prior art literature Patent Literature

Patent Document 1: International Publication No. 2020/116045

Summary of Invention The problem to be solved by the invention

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

The present invention has been accomplished in order to solve the above-mentioned conventional problems, and its main object is to provide an optical laminate having high luminance, suppressed luminance unevenness, excellent strength as a single body, and suppressed light leakage in a high-humidity environment. means of solving problems

An optical laminate according to an embodiment of the present invention includes: a light guide plate; an adhesive layer disposed on the light guide plate in a plan view point pattern; A refractive index reinforcement part; and an optical member laminated on the light guide plate through the adhesive layer and the low refractive index reinforcement part. The adhesive layer forms a pattern in which the dot density increases along the light guide direction from the light incident side of the light guide plate. In the region between the light guide plate and the optical member where the adhesive layer and the low-refractive-index reinforcing portion are not arranged, with the surface on the side of the adhesive layer of the light guide plate and the surface on the side of the adhesive layer of the optical member A low-refractive index layer is disposed in contact with at least one surface. The refractive index of the low-refractive index portion and the low-refractive index layer is 1.30 or less. In one Embodiment, the said low-refractive-index layer is arrange|positioned so that both surfaces may contact the surface of the adhesive layer side of the said light guide plate, and the surface of the said optical member. In one embodiment, the low-refractive-index layer fills the entire region between the light guide plate and the optical member in which the adhesive layer and the low-refractive-index reinforcing portion are not disposed. In one Embodiment, the refractive index of the said low-refractive-index part and the said 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 bonding microporous particles to each other. In one embodiment, the said low-refractive-index reinforcing part has a base material, the low-refractive-index part formed in this base material, and the adhesive layer provided on both surfaces as outermost layers. In one Embodiment, the total width of the said low-refractive-index reinforcement part is 10% or less of the width of the said light guide plate. In an embodiment, the total light transmittance of the said low-refractive-index reinforcing part is 85% or more. In one embodiment, the optical layered system is further provided with a low-refractive index reinforcing portion at the end portion of the light guide plate on the opposite side to the light incident side. Invention effect

According to the present invention, in an optical laminate having a light guide plate and an optical member, and having a top-view dot pattern having a gradient of dot density along the light guide direction of the light guide plate, the adhesive layer is formed along the light guide plate along the light guide plate. Both ends of the light direction are provided with low-refractive index reinforcing parts including low-refractive index parts, and in the region between the light guide plate and the optical member where the adhesive layer and the low-refractive index reinforcing part are not arranged, so as to be consistent with the low-refractive index reinforcing part. The low-refractive index layer is provided so that at least one of the surface on the adhesive layer side of the light guide plate and the surface on the adhesive layer side of the optical member are in contact with each other, and the refractive index of the low-refractive index portion and the low-refractive index layer is set to 1.30 or less , it is possible to realize an optical laminate having high brightness, suppressed brightness unevenness, excellent strength as a single body, and suppressed light leakage in a high-humidity environment.

Form for carrying out the invention

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

A. Overall structure of the optical laminate 1A is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention; FIG. 1B is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention; and FIG. 1C is an optical laminate according to another embodiment of the present invention. A schematic cross-sectional view of the body; FIG. 2 is a schematic plan view showing a state in which the optical layered body of FIG. 1A is removed from the optical member. The optical laminate 100 of FIG. 1A includes: a light guide plate 10; an adhesive layer 20 disposed on the light guide plate 10 in a top-view point pattern; low-refractive-index reinforcing portions 40 disposed at both ends of the light guide plate 10 along the light guide direction; And the optical member 30 laminated on the light guide plate 10 via the adhesive layer 20 and the low-refractive index reinforcing portion 40 . As shown in FIG. 2 , the adhesive layer 20 forms a pattern in which the dot density increases from the light incident side of the light guide plate along the light guide direction (direction to the right from the left side of the drawing). By providing an adhesive layer with a dot pattern with such a density gradient, total reflection of the air can be utilized at the light incident side end of the light guide plate with a large amount of light, so that very good light transmission can be achieved in the light guide plate. As a result, luminance can be improved and luminance unevenness (difference in luminance between a portion closer to the light incident side and a portion farther from the light incident side) can be significantly suppressed. On the other hand, the adhesive strength of such an adhesive layer is not uniform (specifically, the adhesive strength on the light-incident side is small, and the adhesive strength on the side opposite to the light-incidence side is large), and as a result, the optical layered product is a single object. of insufficient strength. On the other hand, by providing the low-refractive-index reinforcing portion, sufficient strength as a single object of the optical layered body can be realized. Furthermore, 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 utilization efficiency of light will not be lowered (as a result, high brightness can be maintained and low brightness can be suppressed. (2) Since the optical laminate can be formed into an elongated shape, the influence on the display area of the image display device to which the optical laminate can be applied can be minimized.

In the embodiment of the present invention, the region between the light guide plate 10 and the optical member 30 where the adhesive layer 20 and the low-refractive index reinforcing portion 40 are not disposed (ie, the gap portion of the optical laminate), so as to be in contact with the light guide plate 10 . The low refractive index layer 50 is arranged so that at least one of the surface on the side of the adhesive layer 20 and the surface on the side of the adhesive layer 20 of the optical member 30 is in contact with each other. In one embodiment, the low refractive index layer 50 is arranged so as to be in contact with both surfaces of the light guide plate 10 on the adhesive layer 20 side and the surface on the adhesive layer 20 side of the optical member 30 . In the example shown in FIG. 1A , the low refractive index layer 50 fills the entire region between the light guide plate 10 and the optical member 30 where the adhesive layer 20 and the low refractive index reinforcing portion 40 are not arranged (ie, the entire optical layered body). void area). By providing such a low-refractive index layer, light leakage in a high-humidity environment can be suppressed. More details are as follows. The applicant has developed an optical laminate comprising: a light guide plate; an adhesive layer arranged on the light guide plate with a pattern in which the dot density increases from the light incident side of the light guide plate along the light guide direction; arranged on the edge of the light guide plate Low-refractive-index reinforcing parts facing both ends in the light-guiding direction; and an optical member laminated on a light-guiding plate through an adhesive layer and a low-refractive-index reinforcing part. Such an optical layered product has high brightness, suppressed brightness unevenness, and is excellent in strength as a single body. On the other hand, the present inventors discovered a new problem that light leakage may occur in such an optical laminate in a high-humidity environment, and found that the cause of the light leakage is that in a high-humidity environment, the gap between the light guide plate and the optical member is Coagulation occurs in the regions (voids) in between where the adhesive layer and the low-refractive-index reinforcing portion are not arranged. Furthermore, the present inventors have studied the relationship between condensation and light leakage, and as a result, they have found that by providing a low-refractive index layer in the void portion, the excellent characteristics of the above-mentioned optical laminate of the present applicant can be maintained, and light leakage due to condensation can be suppressed. , and finally complete the present invention. That is, as shown in FIGS. 1A to 1C , by arranging the low-refractive index layer in the void portion, even if condensation occurs, light leakage from the surface opposite to the adhesive layer 20 side of the optical member 30 can be suppressed. Furthermore, as shown in FIG. 1A , since the void portion is filled with the low refractive index layer, the void portion is substantially absent, so that condensation can be significantly suppressed, and as a result, light leakage can be significantly suppressed. In addition, by disposing the low refractive index layer in the void portion, the difference in refractive index with the void portion (air portion, refractive index 1.00) can be reduced. As a result, since the utilization efficiency of light is not substantially lowered, it is possible to maintain the excellent characteristics of the above-mentioned optical layered body that maintains high brightness and suppresses uneven brightness. Furthermore, the following advantages can also be obtained. When the optical layered body is pressed, if there is a void portion, the light guide plate may come into contact with the optical member, and light leakage may occur due to the contact. Since this contact can be avoided by arranging the low refractive index layer in the void portion, light leakage due to the above-mentioned mechanism can also be suppressed.

The low-refractive index layer 50 can be arranged in contact with the surface on the adhesive layer side of the light guide plate and the surface on the adhesive layer side of the optical member, and can be filled in the gap as shown in FIG. The optical member 30 may be arranged so as to be in contact only with the surface on the adhesive layer 20 side of the optical member 30 , or may be arranged only in contact with the surface of the light guide plate 10 on the adhesive layer 20 side as shown in FIG. 1C . In any configuration, 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. The structure of FIG. 1A is preferred. The reason for this is that it has an effect of suppressing condensation itself (resulting in an effect of suppressing light leakage).

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 is generally composed of a film or plate of resin (preferably transparent resin), or glass. Typical examples of such resins include thermoplastic resins and reactive resins (eg, ionizing radiation curable resins). Specific examples of thermoplastic resins include (meth)acrylic resins such as polymethyl methacrylate (PMMA) and polyacrylonitrile, polycarbonate (PC) resins, polyester resins such as PET, and cellulose triacetate. (TAC) and other cellulose-based resins, cyclic polyolefin-based resins, and styrene-based resins. Specific examples of ionizing radiation curable resins include epoxy acrylate resins and urethane acrylate resins. These resins may be used alone or in combination of two or more.

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

The refractive index of the light guide plate is preferably 1.47 or more, preferably 1.47-1.60, more preferably 1.47-1.55. 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, preferably 0.22 to 0.40, more preferably 0.25 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. Then layer As described above, the adhesive layer 20 is formed in a plan view dot pattern, and the dot density has a gradient that increases along the light guide direction from the light incident side of the light guide plate. With such a structure, the total reflection of the air can be utilized at the light incident side end of the light guide plate with a large amount of light, so that very good light propagation can be realized in the light guide plate. As a result, luminance can be improved and luminance unevenness (difference in luminance between a portion closer to the light incident side and a portion farther from the light incident side) can be significantly suppressed. As shown in FIG. 2 , the gradient of the dot density can be continuously changed along the light guiding direction, or it can also be changed stepwise in each specific area along the light guiding direction. For example, the point density (average) of the area from the end of the light incident side to 10% of the length direction of the light guide plate should be 0%~50%, from the end on the opposite side of the light incident side to the length direction of the light guide plate The point density (average) of the area up to 10% should be 50% to 100%.

The next layer may be composed of an adhesive or an adhesive. Preferably, the adhesive layer is composed of an adhesive. The reason for this is that it is easy to form a pattern. By using an adhesive, pattern formation can be performed by inkjet, printing, or the like. As the adhesive, any suitable adhesive can be used. An active energy ray (eg, ultraviolet, visible light) hardening adhesive is preferred. Specific examples of active energy ray-curable adhesives include acrylic adhesives, epoxy adhesives, vinyl adhesives, thiol adhesives, urethane adhesives, and polysiloxanes. Adhesive. An active energy ray-curable adhesive can also be used in combination with a thermosetting adhesive. As for the adhesive, an adhesive having a high elastic modulus can be exemplified.

The thickness of the next 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 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 Components Regarding the optical member 30, any appropriate optical member that can be laminated with a light guide plate can be exemplified. Specific examples of the optical member include a reflection plate, a diffuser plate, a polar plate, a polarizing plate, a retardation film, a conductive film, a substrate, an image display unit, or an image display panel.

E. Low refractive index reinforcement E-1. Arrangement and overall structure of the low-refractive-index reinforcing part As described above, the low-refractive-index reinforcing parts 40 are disposed on both ends of the light guide plate along the light guide direction. Any appropriate shape can be adopted for the plan view shape of the low-refractive-index reinforcing portion 40 . Specifically, as shown in FIG. 2 , the low-refractive-index reinforcing portion may be continuously formed along the light guide direction of the light guide plate, or may be formed intermittently. 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. When the low-refractive-index reinforcing portion is tapered, the low-refractive-index reinforcing portion may be tapered toward the light incident side, or may be tapered toward the side opposite to the light incident side. When the low-refractive-index reinforcing portion is intermittently formed, the low-refractive-index reinforcing portion may be, for example, a rectangular shape, a dot shape, or any other shape (eg, triangle, square, polygon, semicircle). The length of the low-refractive-index reinforcing portion (that is, the length along the light-guiding direction) is preferably 50% or more, preferably 60% or more, more preferably 70% or more, relative to the total length of the light-guiding plate in the light-guiding direction. More preferably, it is 80% or more. The upper limit of the length of the low-refractive index reinforcement portion is 100% relative to the total length of the light guide plate in the light guide direction. That is, the low-refractive-index reinforcing portion can be provided across the entire light guide direction of the light guide plate. When the length is within such a range, a sufficient reinforcing effect (that is, the strength as a single object of the optical layered body) can be achieved. In addition, when the low-refractive-index reinforcing portion is formed intermittently, the length of the low-refractive-index reinforcing portion is the sum of the respective lengths. In addition, the lengths of the low-refractive-index reinforcing portions may be the same or different, respectively. The width of the low-refractive-index reinforcing portion (ie, the length along the direction perpendicular to the light-guiding direction) is preferably 5% or less relative to the width of the light-guiding plate, respectively. The total width of the low-refractive index reinforcing portion is preferably 10% or less, 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 portion may be, for example, 1% or more. If the width is within such a range, it is possible to secure the strength of an object as an optical laminate 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, preferably 90% or more. If the total light transmittance is in such a range, the intensity of the optical laminate 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 parts can be arranged on both ends of the light guide plate along the light-guiding direction, and can also be arranged on the inner side with a certain distance from the two ends. Preferably, the low-refractive index reinforcing portion is disposed at or near both ends of the light guide plate along the light guide direction. If so constructed, the influence on the display area can be minimized.

When forming the low-refractive-index reinforcing part continuously, the low-refractive-index reinforcing part can be arranged at the center of the light guide plate in the light-guiding direction, or at an offset position (eg, the light-incident side, the side opposite to the light-incidence side). When the low-refractive-index reinforcing portions are intermittently formed, the respective arrangement densities may be uniform across the entire light-guiding direction, or may vary along the light-guiding direction.

As described above, the low-refractive-index reinforcing portion may be provided on both ends of the light guide plate along the light guide direction. Therefore, the low-refractive-index reinforcing portion may be provided at any suitable position other than the above-mentioned positions. In one embodiment, the low-refractive-index reinforcing portion may be further provided at the end portion of the light guide plate on the opposite side to the light incident side. With such a structure, 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 includes a base material 41, a low-refractive index portion 42 formed on the base material 41, and adhesive layers 43 and 44 provided on both surfaces as outermost layers. That is, the low-refractive index reinforcing portion is constituted in the form of a double-sided tape, and the light guide plate and the optical member are bonded together by the adhesive layer on both sides. In addition, as can be understood from the drawings, the low refractive index portion 42 is substantially a low refractive index layer, but is referred to as a low refractive index portion in this specification in order to be easily distinguished from the low refractive index layer 50 .

E-2. Substrate The base material 41 is usually composed of a film or plate of resin (preferably transparent resin). Typical examples of such resins include thermoplastic resins and reactive resins (eg, ionizing radiation curable resins). Specific examples of thermoplastic resins include (meth)acrylic resins such as polymethyl methacrylate (PMMA) and polyacrylonitrile, polycarbonate (PC) resins, polyester resins such as PET, and cellulose triacetate. (TAC) and other cellulose-based resins, cyclic polyolefin-based resins, and styrene-based resins. Specific examples of ionizing radiation curable resins include epoxy acrylate resins and urethane acrylate resins. 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 base material is preferably 1.47 or more, preferably 1.47-1.60, more preferably 1.47-1.55. Within such a range, the light extracted from the light guide plate can be guided to the image display unit without adversely affecting it.

E-3. Low refractive index part The low-refractive index portion usually has a void inside. The porosity of the low refractive index portion is usually 50% by volume or more, preferably 70% by volume or more, and preferably 80% by volume or more. On the other hand, the void ratio is, for example, 90% by volume or less, or preferably 85% by volume or less. The refractive index of the low-refractive index portion can be set to an appropriate range by setting the porosity within the above-mentioned range. The porosity is the value of the porosity calculated from the value of the refractive index measured with an ellipsometry by Lorentz-Lorenz's formula.

The refractive index of the low refractive index portion is preferably 1.25 or less, preferably 1.20 or less, and more preferably 1.15 or less. The lower limit of the refractive index may be, for example, 1.01. Within such a range, very excellent light utilization efficiency can be realized in the laminated structure of the light guide plate and the optical member obtained through the low-refractive-index reinforcing portion. Unless otherwise stated, the refractive index refers to the refractive index measured at a wavelength of 550 nm. The refractive index is a value measured by the method described in "(I) Refractive Index of Low Refractive Index Layer and Low Refractive Index Reinforcing Portion of Low Refractive Index Reinforcing Portion" in Examples below.

As long as the low-refractive index portion has the desired porosity and refractive index as described above, any appropriate structure may be employed. The low-refractive index portion can be preferably formed by coating, printing, or the like. As a material constituting the low refractive index portion, for example, materials described in International Publication No. WO 2004/113966, JP 2013-254183 A, and JP 2012-189802 A can be used. Specifically, for example, silicon oxide-based compounds; hydrolyzable silanes and/or silsesquioxanes, and partial hydrolyzates and dehydration condensates thereof; organic polymers; silanol group-containing silicon compounds; Active silica obtained by contacting silicate with acid or ion exchange resin; polymerizable monomers (such as (meth)acrylic monomers and styrene monomers); curable resins (such as (meth)acrylic acid) resins, fluororesins, and urethane resins); and combinations of these. 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 long-axis diameter among the long-axis diameter and the short-axis diameter of the void (hole). The size of the void (pore) is, for example, 2 nm to 500 nm. The size of the void (pore) is, for example, 2 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and still more 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 still 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 (with a void layer formed) was put into a capillary of a specific surface area measuring device (manufactured by Micromeritics: ASAP2020), and then dried under reduced pressure at room temperature for 24 hours to remove the gas in the void structure. Degassed. Then, by making nitrogen gas adsorb|suck to the said sample, the adsorption isotherm was drawn, and the pore distribution was calculated|required. 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 haze range 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, for example, by the following method. In addition, haze is an index|index of the transparency of a low refractive index part. The void layer (low refractive index portion) was cut into a size of 50 mm×50 mm, and the haze was measured by setting it in a haze meter (manufactured by Murakami Color Institute: HM-150). The haze value was calculated from the following formula. Haze(%)=[Diffuse transmittance(%)/Total light transmittance(%)]×100(%)

The low-refractive-index part which has a void in the said inside is mentioned the low-refractive-index part which has a porous layer and/or an air layer in at least a part. The porous layer usually contains aerogels and/or particles (eg, hollow fine particles and/or porous particles). The low-refractive index portion is preferably a nanoporous layer (specifically, a porous layer in which more than 90% of the micropores have a diameter in the range of 10 ⁻¹ nm to 10 ³ nm).

Regarding the above-mentioned particles, any appropriate particles can be adopted. The particles are usually composed of a silicon oxide-based compound. The particle shape includes, for example, a spherical shape, a plate shape, a needle shape, a cluster shape, and a bunch of grapes. The string-shaped particles include, for example, particles in which a plurality of particles having spherical, plate-like or needle-like shapes are connected to form beads, and particles in the form of short fibers (for example, the short fibers described in Japanese Patent Laid-Open No. 2001-188104) particles), and combinations of these. String-shaped particles may be linear or branched. As a bunch of grape-shaped particles, for example, a plurality of spherical, plate-shaped, and needle-shaped particles are aggregated to form a bunch of grapes. The particle shape can be confirmed, for example, by observation with a transmission electron microscope.

The thickness of the low refractive index portion is preferably 0.2 μm to 5 μm, preferably 0.3 μm to 3 μm. When the thickness of the low-refractive index portion is within such a range, the effect of preventing breakage is significant. Furthermore, the above-mentioned desired thickness ratio can be easily achieved.

Hereinafter, an example of a specific structure 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 constituent units forming a fine void structure, and the constituent units are chemically bonded to each other via a catalytic action. As for the shape of a structural unit, a particle shape, a fiber shape, a rod shape, and a flat shape are mentioned, for example. The constituent unit may have only one shape, or may have two or more shapes in combination. Hereinafter, the case where the low-refractive-index portion is the void layer of the porous body in which the microporous particles are chemically bonded to each other will be mainly described.

Such a void layer can be formed, for example, by chemically bonding fine porous particles to each other in the void layer forming step. Furthermore, in the embodiment of the present invention, the shape of "particles" (for example, the above-mentioned microporous particles) is not particularly limited, and may be spherical or other shapes, for example. Furthermore, in the embodiment of the present invention, the microporous particles may be, for example, sol-gel beads, nanoparticles (hollow nano-silica or nano-balloon particles), nanofibers, and the like. Microporous particles usually contain inorganic substances. Specific examples of inorganic substances 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 microporous particles are, for example, microporous particles of silicon compounds, and the porous body is, for example, a polysiloxane porous body (which also includes a porous body containing silicon oxide and/or silsesquioxane as a constituent unit). . The microporous particles of the silicon compound include, for example, a pulverized body of a gel-like silicon oxide compound. In addition, as for other forms of the low-refractive index portion having at least a part of a porous layer and/or an air layer, there is, for example, a void layer composed of a fibrous substance such as nanofibers, and the fibrous substance is intertwined to form voids, thereby constituting a layer . The method for producing the void layer is not particularly limited, and for example, it is the same as the void layer of the porous body in which the microporous particles are chemically bonded to each other. As another form, the void layer formed using hollow nanoparticles or nanoclay, and the void layer formed using hollow nanoballoons or magnesium fluoride can be mentioned. The void layer may be a void layer composed of a single constituent substance or a void layer composed of a plurality of constituent substances. The void layer may be constituted by a single above-mentioned form, or may be formed by including a plurality of the above-mentioned forms.

In this embodiment, the porous structure of the porous body may be, for example, a continuous cell structure in which the pore structure is continuous. The so-called continuous-cell structure, for example, refers to a three-dimensionally connected pore structure in the above-mentioned polysiloxane porous body, and can also be said to be a state in which the internal voids of the pore structure are continuous. The porosity can be increased by the porous body having a continuous cell structure. Among them, when single-cell particles (particles each having a pore structure) such as hollow silicon oxide are used, a continuous-cell structure cannot be formed. On the other hand, when using, for example, silica sol particles (a pulverized product of a gel-like silicon compound that forms a sol), since the particles have a three-dimensional tree-like structure, the tree-like particles are not present in the coating film (containing the gel-like silicon compound). The pulverized sol coating film) settles and accumulates, whereby a continuous bubble structure can be easily formed. The low-refractive index portion more preferably has a co-continuous structure in which a continuous cell structure includes a distribution of a plurality of pores. The co-continuous structure refers to, for example, a hierarchical structure including a structure in which nano-sized fine voids are present and an interconnected cell structure in which the nano-voids are aggregated. When forming a co-continuous structure, for example, fine voids can provide film strength and coarse intercellular voids can provide high porosity, and both film strength and high porosity can be achieved. Such a co-continuous structure is preferably formed by controlling the pore distribution of the generated void structure in a gel (gel-like silicon compound) at a stage before pulverization into silica sol particles. Furthermore, for example, when the gelatinous silicon compound is pulverized, a co-continuous structure can be formed by controlling the particle size distribution of the pulverized silica sol particles to a desired size.

The low-refractive index portion includes, for example, pulverized products 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 objects in the low-refractive index portion is not particularly limited, and examples thereof include a cross-link bond, a covalent bond, and a hydrogen bond.

The volume average particle diameter of the above-mentioned pulverized material 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 apparatus such as dynamic light scattering and laser diffraction, and an electron microscope such as a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Furthermore, the volume average particle size is an index of the particle size deviation of the pulverized material.

The kind of the gel-like compound is not particularly limited. The gel-like compound may, for example, be a gel-like silicon compound.

Moreover, in the low-refractive-index portion (void layer), it is preferable that, for example, the silicon atom contained is a siloxane bond. As a specific example, the ratio of unbonded silicon atoms (ie, residual silanols) in all silicon atoms contained in the void layer is, for example, less than 50%, preferably 30% or less, and more preferably 15% or less.

Hereinafter, an example of the formation method of such a low refractive index part is demonstrated.

This method generally includes a precursor forming step of forming a void structure as a precursor of a low refractive index portion (void layer) on a resin film, and a crosslinking reaction causing a crosslinking reaction inside the precursor after the precursor forming step. step. The method further includes a step of preparing a liquid containing fine pore particles (hereinafter sometimes referred to as a "liquid containing fine pores" or simply "containing liquid"), and a drying step of drying the liquid, In the precursor forming step, the microporous particles in the dried body are chemically bonded to each other to form the precursor. The containing liquid is not particularly limited, and is, for example, a suspension containing fine pore particles. In addition, the following mainly describes the case where the microporous particles are a pulverized product of a gel-like compound, and the void layer is a porous body (preferably a polysiloxane porous body) containing a pulverized product of the gel-like compound. However, even when the microporous particles are other than the pulverized product of the gel-like compound, the low refractive index portion is formed in the same manner.

According to the above-described method, for example, a low refractive index portion (void layer) having a very low refractive index can be formed. The reason for this is presumed, for example, as follows. However, this estimation is not intended to limit the formation method of the low refractive index portion.

Since the above-mentioned pulverized product is obtained by pulverizing the gel-like silicon compound, the three-dimensional structure of the gel-like silicon compound before pulverization is in a state of being dispersed into a three-dimensional basic structure. Furthermore, in the above-mentioned method, a precursor of a porous structure based on a three-dimensional basic structure is formed by coating a fragment of a gelatinous silicon compound on a resin film. That is, according to the above-mentioned method, a new porous structure (three-dimensional basic structure) using the coated pulverized material, which is different from the three-dimensional structure of the gel-like silicon compound, can be formed. Therefore, in the void layer finally obtained, a low refractive index that functions to the same extent as, for example, an air layer can be achieved. Furthermore, in the above-mentioned method, since the pulverized materials are chemically bonded to each other, the three-dimensional basic structure is fixed. Therefore, the voided layer finally obtained can maintain sufficient strength and flexibility despite having a voided structure.

The specific structure and detailed formation method of the low-refractive index portion are described in, for example, International Publication No. WO 2019/151073. The description of this gazette is incorporated in this specification as a reference.

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

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

As shown in FIG. 1A , when the low-refractive index layer fills the voids, 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 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. 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 is preferably 0.6 μm or more, 0.75 μm or more, and 0.80 μm or more, and the upper limit is preferably 3 μm or less. , 2μm or less.

The size of the voids (holes) in the low refractive index layer is preferably 400 nm or less, preferably 300 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less. If the size of the voids (holes) in the low-refractive index layer is within such a range, the permeation of water can be well suppressed, and thus the coagulation can be well suppressed. As a result, light leakage can be suppressed favorably. The smaller the size of the voids (pores), the better, and the lower limit may be, for example, 2 nm. Example

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

(I) Refractive index of the low-refractive index portion of the low-refractive index layer and the low-refractive index reinforcing portion After the low-refractive index layer is formed on the acrylic film, it is cut into a size of 50 mm×50 mm, and it is attached to the surface of the glass plate (thickness: 3 mm) through the adhesive layer. The center part of the back surface (about 20 mm in diameter) of the glass plate was filled with black marks to form a sample that does not reflect on the back surface of the glass plate. The above-mentioned sample was set in an ellipsometer (manufactured by J.A. 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) Uneven brightness With respect to the optical laminates obtained in Examples and Comparative Examples, the light from the LED was incident from the end of the light guide plate of the optical laminate, and unevenness in luminance was observed visually. Evaluation was performed according to the following criteria. ○: The overall brightness (brightness) of the laminate is uniform ╳: Light leakage, uneven brightness, and/or fewer bright areas are confirmed (III) Strength When the optical laminates obtained in Examples and Comparative Examples were processed, it was checked whether or not the light guide plate and the thin film were peeled off. Evaluation was performed according to the following criteria. ○: No peeling occurred, and can be handled as a single body without any problem ╳: Peeling occurred (IV) Light leakage The optical laminates obtained in Examples and Comparative Examples were placed in a constant temperature and humidity tank controlled at 20° C. and 98% RH for 1 hour to perform humidification treatment. The optical layered body after the humidification treatment was incident on the LED light from the light incident side end of the light guide plate, and the presence or absence of light leakage was visually inspected. Evaluation was performed according to the following criteria. ○: Confirm that there is no light leakage and the brightness is uniform ╳: Confirm that there is light leakage and uneven brightness

[Production Example 1] Preparation of a coating liquid for forming a low refractive index layer (1) Gelation of silicon compounds Mixed solution A was prepared by dissolving 0.95 g of methyltrimethoxysilane (MTMS), which is a precursor of a silicon compound, in 2.2 g of dimethyl sulfoxide (DMSO). 0.5 g of a 0.01 mol/L oxalic acid aqueous solution was added to the mixed solution A, and the mixture was stirred at room temperature for 30 minutes to hydrolyze MTMS to generate a mixed solution B containing tris(hydroxy)methylsilane. After adding 0.38 g of 28% by weight ammonia water and 0.2 g of pure water to 5.5 g of DMSO, the above-mentioned mixed solution B was further added, and the mixture was stirred at room temperature for 15 minutes to perform gelation of tris(hydroxy)methylsilane. , to obtain a mixed solution C containing a gelatinous silicon compound. (2) Aging treatment The mixed solution C containing the gelatinous silicon compound prepared as described above was cultured at 40° C. for 20 hours as it was, and then matured. (3) crushing treatment Next, the gelatinous silicon compound subjected to the aging treatment as described above is pulverized into particles of several mm to several cm in size using a spatula. Then, 40 g of isopropanol (IPA) was added to the mixed solution C, and after slight stirring, it was left to stand at room temperature for 6 hours, and the solvent and catalyst in the gel were decanted. By performing the same decantation treatment three times, solvent replacement was performed, and a mixed solution D was obtained. Next, the gelatinous silicon compound in the mixed solution D is subjected to pulverization treatment (high-pressure non-medium pulverization). The pulverization treatment (high-pressure non-medium pulverization) was performed by using a homogenizer (manufactured by SMT Corporation, trade name "UH-50") to weigh 1.85 g of the gel-like compound and 1.15 g of IPA in the mixed solution D in a 5cc screw-top bottle. Grinding was performed for 2 minutes under the conditions of 50W and 20kHz. By the pulverization process, the gelatinous silicon compound in the mixed solution D is pulverized, whereby the mixed solution D' becomes a sol solution of the pulverized product. The volume average particle diameter, which represents the particle size deviation, of the pulverized material contained in the mixed solution D' was confirmed by a dynamic light scattering type NANOTRAC particle size analyzer (manufactured by Nikkiso Co., Ltd., UPA-EX150), and was 0.50 to 0.70. Further, to 0.75 g of the sol solution (mixed solution D'), a 1.5 wt% concentration MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd.: trade name WPBG266) was added in the following proportions 0.062 g and 0.036 g of a 5% concentration MEK solution of bis(trimethoxysilyl)ethane to obtain a coating solution A for forming a low refractive index layer.

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

[Production Example 3] Preparation of adhesive Put 90.7 parts of butyl acrylate, 6 parts of N-acryloylmorpholine, 3 parts of acrylic acid, 0.3 parts of 2-hydroxybutyl acrylate, 0.1 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 g of ethyl acetate were introduced into nitrogen gas while stirring slowly and replaced with nitrogen gas. A polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. To 100 parts of solid content of the obtained acrylic polymer solution, 0.2 part of an isocyanate crosslinking agent (CORONATE L manufactured by Nippon Polyurethane Industry Co., Ltd., an adduct of toluene diisocyanate of trimethylolpropane), and benzyl peroxide were added. Acrylic adhesive solution was prepared by 0.3 part of glutinous acid (NYPER BMT manufactured by NOF Corporation) and 0.2 part of γ-glycidoxypropylmethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.: KBM-403). Next, the above-mentioned acrylic adhesive solution was coated on a polysiloxane-treated polyethylene terephthalate (PET) film (Mitsubishi Chemical polyester film) in such a manner that the thickness of the adhesive layer after drying became a specific thickness One side of the company's product, thickness: 38 μm) was dried at 150° C. for 3 minutes to form an adhesive layer.

[Production Example 4] Production of a laminate of double-sided adhesive layers (low-refractive-index reinforcing portion) The coating liquid A for forming a low refractive index layer prepared in Production Example 1 was applied to a base material (acrylic film) having a thickness of 30 μm. The wet thickness (thickness before drying) of the coating layer was about 27 μm. The coating 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 base material. The refractive index of the obtained low refractive index portion was 1.18. Next, the adhesive layers formed in Production Example 3 were placed on both sides of the laminate of the substrate/low refractive index portion (the thickness of the adhesive layer on the low refractive index portion side was 10 μm, and the thickness of the adhesive layer on the substrate side was 75 μm). , to make a laminate with double-sided adhesive layers.

[Example 1] The coating solution A for forming a low refractive index layer prepared in Production Example 1 was coated on a light guide plate (acrylic plate, thickness 400 μm, full length in the light guide direction 85 mm, width 60 mm, refractive index 1.49), and then dried, A low refractive index layer (refractive index 1.18, thickness 1 μm) was formed. Next, the low-refractive-index layer was cut out 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-guiding direction were removed with a doctor blade, and the laminated body of the double-sided adhesive layer produced in Production Example 4 was pasted on the removed portion to form a low-refractive index reinforcing portion. Furthermore, an epoxy adhesive (manufactured by Toagosei Co., Ltd., product name "LCR0632") was inkjet printed on the portion where the dot pattern was formed to form an adhesive layer with a pattern as shown in FIG. 2 . Through the low-refractive-index reinforcing part and the adhesive layer, a phosphine film was bonded to the light guide plate to produce an optical laminate. In the obtained optical layered product, the thickness of the low-refractive-index reinforcing portion and the thickness of the adhesive layer were the same (115.9 μm). In addition, the obtained optical laminated body corresponds to the structure of FIG. 1C. The obtained optical layered body was subjected to the evaluations of the above (II) to (IV). The results are shown in Table 1.

[Example 2] The same procedure as in Example 1 was carried out, except that the coating liquid B for forming a low refractive index layer prepared in Production Example 2 was used instead of the coating liquid A for forming a low refractive index layer to form a low refractive index layer (refractive index 1.25, thickness 1 μm). Methods An optical laminate was produced. The obtained optical layered body was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Example 3] The laminated body of the double-sided adhesive layer produced in Production Example 4 was pasted on both ends of the same light guide plate as in Example 1 along the light guide direction to form a low-refractive index reinforcing portion. Furthermore, the coating liquid A for low-refractive-index layer formation was apply|coated to a light guide plate, and it was made to dry, and the low-refractive-index layer of the same thickness (115.9 micrometers) as a low-refractive-index reinforcement part was formed. Then, an epoxy adhesive (manufactured by Toagosei Co., Ltd., product name "LCR0632") was inkjet-printed in the same dot pattern as in Example 1 to form an adhesive layer. The printed adhesive was permeated into the low-refractive index layer, and the voids of the low-refractive index layer were filled, and then a fluorine thin film was pasted thereon to obtain an optical laminate. The obtained optical laminate corresponds to the structure of FIG. 1A . The obtained optical layered body was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Comparative Example 1] The laminated body of the double-sided adhesive layer produced in Production Example 4 was pasted on both ends of the same light guide plate as in Example 1 along the light guide direction to form a low-refractive index reinforcing portion. Furthermore, on the light guide plate, an epoxy adhesive (manufactured by Togosei Corporation, product name "LCR0632") was inkjet-printed in the same dot pattern as in Example 1 to form an adhesive layer. Through the low-refractive-index reinforcing part and the adhesive layer, the fluorine film is pasted on the light guide plate to be integrated. Next, a polysiloxane-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 film, and hardened to obtain an optical laminate. . The obtained optical layered body was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

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

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

[Comparative Example 4] On the same light guide plate as in Example 1, an epoxy adhesive (manufactured by Toagosei Co., Ltd., product name "LCR0632") was inkjet-printed in the same dot pattern as in Example 1 to form an adhesive layer. An optical layered body was obtained by laminating the fluorine film on the light guide plate through the adhesive layer and integrating them. That is, except that the low-refractive-index reinforcing portion and the low-refractive-index layer were not provided, an optical layered body was produced in the same manner as in Example 1. The obtained optical layered body was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[Table 1] low refractive index layer Reinforcing Department uneven brightness strength light leakage Example 1 Have Have ○ ○ ○ Example 2 Have Have ○ ○ ○ Example 3 Have Have ○ ○ ○ Comparative Example 1 None (high refractive index layer) Have ╳ ○ ╳ Comparative Example 2 Have none ○ ╳ ○ Comparative Example 3 none Have ○ ○ ╳ Comparative Example 4 none none ○ ╳ ╳

As can be seen from Table 1, according to the examples of the present invention, an optical laminate having high brightness, suppressed brightness unevenness, excellent strength as a single body, and suppressed light leakage can be obtained. In Comparative Example 1 in which the void portion between the light guide plate and the optical member was filled with a high-refractive material, there were few bright areas and light leakage was observed. In Comparative Example 2 in which the reinforcing portion was not provided, the strength as an integral body was insufficient. 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 a single body was insufficient, and light leakage was observed. industrial availability

The optical laminate of the present invention can be suitably used for optical devices (eg, image display devices, lighting devices) that extract light using a light guide plate.

10: Light guide plate 20: Next layer 30: Optical components 40: Low refractive index reinforcement 41: Substrate 42: Low refractive index part 43: Adhesive layer 44: Adhesive layer 50: Low refractive index layer 100: Optical Laminate 101: Optical Laminate 102: Optical Laminate

1A is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention. 1B is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention. 1C is a schematic cross-sectional view of an optical laminate according to another embodiment of the present invention. FIG. 2 is a schematic plan view showing a state in which an optical member is removed from the optical laminate of FIG. 1A . 3 is a schematic cross-sectional view showing an example of a low-refractive-index reinforcing portion used in the optical laminate according to the embodiment of the present invention.

10: Light guide plate

20: Next layer

30: Optical components

50: Low refractive index layer

100: Optical Laminate

Claims (9)

An optical laminate having: light guide plate; Disposing on the adhesive layer of the light guide plate in a top view point pattern; a low-refractive-index reinforcing portion including a low-refractive-index portion disposed at both ends of the light guide plate along the light-guiding direction; and an optical component laminated on the light guide plate through the adhesive layer and the low-refractive-index reinforcing part; The adhesive layer forms a pattern in which the dot density increases along the light guide direction from the light incident side of the light guide plate; In the region between the light guide plate and the optical member where the adhesive layer and the low-refractive-index reinforcing portion are not arranged, with the surface on the side of the adhesive layer of the light guide plate and the surface on the side of the adhesive layer of the optical member A low-refractive-index layer is configured in a manner of contacting at least one side; The refractive index of the low-refractive index portion and the low-refractive index layer is 1.30 or less. The optical laminate according to claim 1, wherein the low-refractive index layer is arranged in contact with both surfaces on the adhesive layer side of the light guide plate and the surface on the adhesive layer side of the optical member. The optical laminate according to claim 2, wherein the low-refractive-index layer fills the entire region between the light guide plate and the optical member where the adhesive layer and the low-refractive-index reinforcing portion are not disposed. 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 porous particles to each other. The optical laminate 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 adhesive layers provided on both surfaces as outermost layers. 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 the end portion of the light guide plate on the opposite side to the light incident side.

Images