JP2025118170A - Optical member, manufacturing method thereof, and optical device using said optical member - Google Patents

Abstract

To provide an optical member that has a light guide plate and a low refractive index layer, has a strength sufficient enough to prevent them from being peeled off, and has excellent light guide performance.SOLUTION: An optical member according to an embodiment of the present invention has: a light guide plate; a low refractive index layer that is provided on one principal surface of the light guide plate; a stress relaxation layer that is provided on the low refractive index layer on the opposite side of the light guide plate, and has a storage elastic modulus of 0.01 MPa to 10 MPa; and a protective layer that is provided on the stress relaxation layer on the opposite side of the low refractive index layer, and has an elastic modulus in tension of 20 MPa or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical member, a method for manufacturing the same, and an optical device using the optical member.

A technology is known in which a low-refractive index layer is formed on a light guide plate to optically isolate the light being guided through the light guide plate, thereby guiding the light while minimizing the effects of external factors (e.g., scratches or dirt on the light guide plate). For example, an optical sheet is known in which a low-refractive index layer is laminated on a light guide plate via an adhesive layer. However, this technology can cause color shift and/or scattering due to the adhesive layer, resulting in light guide loss. To solve this problem, a technology is being considered in which a low-refractive index layer is laminated directly on the light guide plate. However, laminating a low-refractive index layer directly on the light guide plate results in a problem in that the strength of the laminate is also low due to the low strength of the low-refractive index layer.

Patent No. 6606518 Japanese Patent Application Laid-Open No. 2023-048451

The present invention was made to solve the above-mentioned problems of the prior art, and its main objective is to provide an optical component that has a light guide plate and a low refractive index layer, has sufficient strength as a laminate, and has excellent light guide performance.

[1] An optical member according to an embodiment of the present invention includes a light guide plate; a low refractive index layer provided on one main surface of the light guide plate; a stress relaxation layer provided on the side of the low refractive index layer opposite the light guide plate, the stress relaxation layer having a storage modulus of 0.01 MPa to 10 MPa; and a protective layer provided on the side of the stress relaxation layer opposite the low refractive index layer, the protective layer having a tensile modulus of 20 MPa or more.
[2] In the above [1], the refractive index of the low refractive index layer is 1.25 or less.
[3] In the above [1] or [2], the low refractive index layer has a thickness of 5 μm or less.
[4] In any one of the above [1] to [3], the haze of the low refractive index layer is less than 5%.
[5] In any one of the above [1] to [4], the low refractive index layer is directly laminated on the light guide plate.
[6] In any one of the above [1] to [5], the stress relaxation layer has a storage modulus of 0.08 MPa to 0.20 MPa and a thickness of 5 μm to 20 μm.
[7] According to another aspect of the present invention, there is provided an optical device, the optical device including the optical member according to any one of [1] to [6] above.
[8] In the above [7], the optical device is selected from a device for AR glasses, a device for MR glasses, a device for VR glasses, a device for a lighting device, or a backlight unit of an image display device.
[9] According to yet another aspect of the present invention, there is provided a method for producing an optical member according to any one of [1] to [6] above. The method includes the steps of forming a low refractive index layer on a first substrate to produce a first laminate, providing a stress relief layer and a second substrate in this order on the low refractive index layer of the first laminate to produce an optical laminate, peeling the first substrate from the optical laminate, and laminating the optical laminate from which the first substrate has been peeled and a light guide plate so that the low refractive index layer and the light guide plate are adjacent to each other.
[10] In the above [9], the manufacturing method includes directly laminating the optical laminate from which the first base material has been peeled and a light guide plate.

According to an embodiment of the present invention, an optical component can be realized that has a light guide plate and a low refractive index layer, has sufficient strength as a laminate, and has excellent light guide performance.

1 is a schematic cross-sectional view of an optical element according to one embodiment of the present invention. 1 is a schematic cross-sectional view illustrating one step in a method for manufacturing an optical member according to an embodiment of the present invention. FIG. 10 is a schematic cross-sectional view illustrating another step in the method for manufacturing an optical member according to an embodiment of the present invention. FIG. 10 is a schematic cross-sectional view illustrating yet another step in the method for manufacturing an optical member according to an embodiment of the present invention. FIG. 10 is a schematic cross-sectional view illustrating yet another step in the method for manufacturing an optical member according to an embodiment of the present invention. FIG. 10 is a schematic cross-sectional view illustrating yet another step in the method for manufacturing an optical member according to an embodiment of the present invention.

Embodiments of the present invention are described below, but the present invention is not limited to these embodiments. For clarity, the drawings are schematic, and the thickness and size of each component of the optical element, as well as the relative thicknesses and other proportions between components, may differ from the actual figures.

A. Overall Configuration of the Optical Element FIG. 1 is a schematic cross-sectional view of an optical element according to one embodiment of the present invention. The illustrated optical element 100 includes a light guide plate 10, a low-refractive index layer 20 provided on one major surface of the light guide plate 10 (the upper major surface in the illustrated example), a stress relief layer 30 provided on the side of the low-refractive index layer 20 opposite the light guide plate 10, and a protective layer 40 provided on the side of the stress relief layer 30 opposite the low-refractive index layer 20. In an embodiment of the present invention, the storage modulus of the stress relief layer is 0.01 MPa to 10 MPa, and the tensile modulus of the protective layer is 20 MPa or greater. With this configuration, a low-refractive index layer is laminated on a light guide plate without the use of an adhesive or pressure-sensitive adhesive, thereby ensuring sufficient strength as a laminate. This effect can be enhanced by providing a stress relief layer on the low-refractive index layer opposite the light guide plate. A configuration in which a low refractive index layer is laminated on a light guide plate without the use of an adhesive or pressure-sensitive adhesive can suppress color shift and/or scattering caused by the adhesive or the like, thereby suppressing light guide loss and achieving excellent light guide performance. Therefore, according to an embodiment of the present invention, an optical component can be realized that has a light guide plate and a low refractive index layer, has sufficient strength as a laminate, and has excellent light guide performance. Furthermore, by setting the storage modulus of the stress relaxation layer and the tensile modulus of the protective layer within the above-mentioned ranges, the effects of the embodiment of the present invention can be made significant.

The low-refractive index layer 20 is typically laminated directly onto the light guide plate 10. In this specification, "direct lamination" refers to lamination of two components (here, the low-refractive index layer and the light guide plate) without an adhesive or pressure-sensitive adhesive layer. Here, "direct lamination" also encompasses the case in which the low-refractive index layer 20 is laminated onto the light guide plate 10 via an adhesion aid layer 50, as in the illustrated example. The adhesion aid layer typically contains a silane coupling agent, and as described below, the formed adhesion aid layer itself does not have any adhesive or pressure-sensitive adhesive properties. Furthermore, as also described below, the adhesion aid layer may be so thin that it is not clearly recognizable as a layer. Therefore, the configuration shown in the illustrated example can also be included in the "direct lamination" category. Incidentally, providing an adhesion aid layer can achieve even greater strength without impairing the light guide performance of the optical component.

The total light transmittance of the optical element is preferably 60% to 99%, more preferably 70% to 98%, and even more preferably 80% to 97%. The haze of the optical element is preferably 0.05% to 3%, more preferably 0.1% to 2.5%, and even more preferably 0.2% to 2%. According to an embodiment of the present invention, excellent transparency can be achieved for the entire optical element. As a result, the optical element can be suitably used for AR glasses, MR glasses, and VR glasses (hereinafter, these may be collectively referred to as "AR glasses, etc."). "AR" is an abbreviation for "Augmented Reality," "MR" is an abbreviation for "Mixed Reality," and "VR" is an abbreviation for "Virtual Reality."

The optical element may be in a long or sheet form. A long optical element can typically be wound into a roll.

The components of the optical element are described in detail below.

B. Light Guide Plate The light guide plate 10 is typically configured so that light incident on the light guide plate propagates through the light guide plate using total reflection and exits in a predetermined direction at a predetermined position. The light guide plate may be made of glass or resin. Examples of resins include thermoplastic resins and reactive resins (e.g., non-ionizing radiation-curable resins such as ultraviolet, visible light, and infrared radiation). Examples of thermoplastic resins include COC resins and COP resins such as cyclic olefin copolymers and cycloolefin resins, acrylic resins such as polymethyl methacrylate (PMMA), resins containing one or more of styrene resins, polycarbonate (PC) resins, polyethylene terephthalate (PET) resins, and acrylonitrile resins as main components, and transparent polyimide resins. Examples of reactive resins include non-ionizing radiation-curable resins such as acrylic, epoxy, urethane, silicone, and enethiol resins.

The refractive index of the light guide plate is preferably 1.4 to 2.5, more preferably 1.5 to 2.4, and even more preferably 1.6 to 2.3. A refractive index within this range can achieve good light input from the outside, good light output to the outside, and good total reflection within the light guide plate.

C. Low Refractive Index Layer The low refractive index layer 20 typically has voids therein. The porosity of the low refractive index layer is preferably 35 vol% or more, more preferably 38 vol% or more, and particularly preferably 40 vol% or more. If the porosity is within this range, a low refractive index layer with a particularly low refractive index can be formed. The upper limit of the porosity of the low refractive index layer is, for example, 90 vol% or less, preferably 75 vol% or less. If the porosity is within this range, a low refractive index layer with excellent strength can be formed. The porosity is a value calculated from the refractive index measured with an ellipsometer using the Lorentz-Lorenz formula.

The refractive index of the low-refractive index layer is, for example, 1.25 or less, preferably 1.23 or less, more preferably 1.22 or less, even more preferably 1.20 or less, and particularly preferably 1.19 or less. On the other hand, the refractive index of the low-refractive index layer is preferably 1.05 or more, more preferably 1.08 or more, and even more preferably 1.10 or more. By providing a low-refractive index layer having such a refractive index on the main surface of the light guide plate, light guide loss can be suppressed without substantially affecting the optical characteristics of the light guide plate, achieving excellent light guide performance. Furthermore, as described below, the low-refractive index layer can be made very thin, contributing to the thinning and weight reduction of optical components (e.g., AR glass). Furthermore, if the refractive index of the low-refractive index layer is within the above range, a predetermined mechanical strength can be ensured and breakage can be suppressed. Unless otherwise specified, the refractive index refers to the refractive index measured at a wavelength of 550 nm or the refractive index converted to a 550 nm value using measurements at other wavelengths and the refractive index wavelength dispersion. The refractive index is a value measured by the method described in "(1) Refractive Index of the Low-Refractive Index Layer" in the Examples section below.

The total light transmittance of the low refractive index layer is preferably 85% to 99%, more preferably 87% to 98%, and even more preferably 89% to 97%. By providing a low refractive index layer with such a refractive index on the main surface of the light guide plate, it is possible to achieve the effects of the refractive index described above while ensuring excellent transparency. As a result, the optical element can be suitably used in AR glass, etc.

The haze of the low refractive index layer is, for example, less than 5%, preferably less than 3%. Meanwhile, the haze is, for example, 0.05% or more, preferably 0.1% or more. By providing a low refractive index layer having such a haze on the main surface of a light guide plate, it is possible to ensure excellent transparency while achieving the effects of the refractive index described above. As a result, the optical member can be suitably used in AR glasses and the like. The haze can be measured, for example, by the following method.
A low refractive index layer is formed on a 50 mm x 50 mm glass sheet, and the sheet is set in a haze meter (HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) to measure the haze. The haze value is calculated using the following formula:
Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] × 100 (%)

The thickness of the low refractive index layer is preferably 5 μm or less, more preferably 4 μm or less, even more preferably 3 μm or less, particularly preferably 2 μm or less, and especially preferably 1.5 μm or less. On the other hand, the thickness of the low refractive index layer is preferably 300 nm or more, more preferably 400 nm or more, and even more preferably 500 nm or more. If the thickness of the low refractive index layer is within this range, excellent transparency can be ensured while light leakage can be effectively suppressed.

The surface roughness Rz of the low refractive index layer on the light guide plate side (the first substrate side described below during the manufacturing process) is preferably 200 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less. This surface roughness is a nearly direct transfer of the surface roughness of the first substrate side that comes into contact with the low refractive index layer, so the surface roughness can be determined when the low refractive index layer-forming material is applied to the first substrate. If the surface roughness Rz of the low refractive index layer is within this range, sufficient adhesion between the low refractive index layer and the light guide plate can be ensured during the optical component manufacturing method described below. As a result, the first substrate can be properly peeled off without damaging the low refractive index layer. Note that Rz refers to the maximum height based on JIS B 0601.

The low-refractive index layer may have any suitable configuration as long as it has the desired properties. The low-refractive index layer is preferably formed by coating or printing. Materials for the low-refractive index layer include those described in International Publication No. 2004/113966, Japanese Patent Application Laid-Open No. 2013-254183, and Japanese Patent Application Laid-Open No. 2012-189802. Representative examples include silicon compounds. Examples of silicon compounds include silica-based compounds; hydrolyzable silanes and their partial hydrolyzates and dehydration condensates; silicon compounds containing silanol groups; and activated silica obtained by contacting silicates with acids or ion-exchange resins. Other examples include organic polymers; polymerizable monomers (e.g., (meth)acrylic monomers and styrene-based monomers); and curable resins (e.g., (meth)acrylic resins, fluorine-containing resins, and urethane resins). These materials may be used alone or in combination. The low refractive index layer can be formed by applying or printing a solution or dispersion of such a material.

The size of the voids (holes) in the low refractive index layer refers to the diameter of the long axis of the voids (holes). The size of the voids (holes) is, for example, 2 nm to 500 nm. The size of the voids (holes) is, for example, 2 nm or more, preferably 5 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more. On the other hand, the size of the voids (holes) is, for example, 500 nm or less, preferably 200 nm or less, and even more preferably 100 nm or less. The size of the voids (holes) ranges, for example, from 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 voids (holes) can be adjusted to the desired size depending on the purpose and application. The size of the voids (holes) can be quantified using the BET test method.

The size of the voids (pores) can be quantified using the BET test method. Specifically, 0.1 g of the sample (the formed void layer) is placed into the capillary of a high-precision gas adsorption measurement device (Microtrac's BELLSORP MINI), and then dried under reduced pressure at room temperature for 24 hours to remove the gas from the void structure. Nitrogen gas is then adsorbed onto the sample, and an adsorption isotherm is plotted to determine the pore distribution. This allows the void size to be evaluated.

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

Any suitable particles may be used as the particles. Particles are typically made of silica-based compounds. Examples of particle shapes include spherical, plate-like, needle-like, string-like, and bunch-of-grapes shapes. Examples of string-like particles include particles consisting of multiple spherical, plate-like, or needle-like particles strung together like beads, short fiber-like particles (such as the short fiber-like particles described in JP 2001-188104 A), and combinations thereof. String-like particles may be linear or branched. Examples of bunch-of-grapes-like particles include particles consisting of multiple spherical, plate-like, and needle-like particles agglomerated to form a bunch of grapes. The particle shape can be confirmed by observation with a transmission electron microscope, for example.

Below, an example of a specific configuration of the low refractive index layer will be described. The low refractive index layer of this embodiment is composed of one or more types of structural units that form a fine void structure, and these structural units are chemically bonded to each other via catalytic action. Examples of the shape of the structural units include particulate, fibrous, rod-like, and flat plate-like. The structural units may have only one shape, or may have a combination of two or more shapes. Below, we will mainly describe the case where the low refractive index layer is a porous void layer in which the above-mentioned fine pore particles are chemically bonded to each other.

Such a void layer can be formed, for example, by chemically bonding microporous particles together during the void layer formation process. In embodiments of the present invention, the shape of the "particles" (e.g., the microporous particles) is not particularly limited and may be, for example, spherical or another shape. In embodiments of the present invention, the microporous particles may be, for example, sol-gel beaded particles, nanoparticles (hollow nanosilica/nanoballoon particles), nanofibers, etc. Microporous particles typically include inorganic materials. Specific examples of inorganic materials 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 a silicon compound, and the porous body is, for example, a silicone porous body. The microporous particles of the silicon compound include, for example, a pulverized gel silica compound. Another example of a low refractive index layer and/or a low refractive index layer having an air layer at least partially therein is a void layer made of a fibrous material such as nanofibers, which are entangled to form voids and form a layer. The method for producing such a void layer is not particularly limited, and can be the same as that for the void layer of a porous material in which microporous particles are chemically bonded to each other. Further examples include void layers made of hollow nanoparticles or nanoclay, and void layers made of hollow nanoballoons or magnesium fluoride. The void layer may be made of a single constituent material, or a void layer made of multiple constituent materials. The void layer may be made of a single constituent material, or may be made of multiple constituent materials.

In this embodiment, the porous structure of the porous body may be, for example, an open-cell structure, in which the pores are interconnected. An open-cell structure refers to a three-dimensionally interconnected pore structure, such as in the silicone porous body described above, and can also be described as a state in which the internal voids of the pore structure are interconnected. Having an open-cell structure in a porous body can increase the porosity. However, when closed-cell particles (particles with individual pore structures) such as hollow silica are used, an open-cell structure cannot be formed. On the other hand, when silica sol particles (pulverized gel-like silicon compound that forms a sol) are used, the particles have a three-dimensional dendritic structure, and the dendritic particles settle and deposit in the coating film (coated film of a sol containing the pulverized gel-like silicon compound), thereby easily forming an open-cell structure. The low refractive index layer more preferably has a monolithic structure in which the open-cell structure includes a distribution of multiple pores. The monolithic structure refers to, for example, a hierarchical structure that includes a structure with nano-sized voids and an open-cell structure in which the nano-voids are aggregated. When forming a monolithic structure, for example, it is possible to achieve both membrane strength through fine pores and high porosity through coarse open-cell pores. Such a monolithic structure can be preferably formed by controlling the pore distribution of the resulting pore structure in the gel (gel silicon compound) prior to pulverization into silica sol particles. Furthermore, for example, when pulverizing a gel silicon compound, a monolithic structure can be formed by controlling the particle size distribution of the pulverized silica sol particles to the desired size.

The low refractive index layer contains, for example, pulverized gel compounds as described above, with the pulverized particles chemically bonded together. There are no particular limitations on the form of chemical bonding between the pulverized particles in the low refractive index layer, and examples include cross-linking, covalent bonding, and hydrogen bonding.

The volume average particle diameter of the pulverized material in the low refractive index layer is, for example, 10 nm or more, preferably 20 nm or more, and more preferably 30 nm or more. On the other hand, the volume average particle diameter is, for example, 500 nm or less, preferably 400 nm or less, and more preferably 300 nm or less. The volume average particle diameter ranges, for example, from 10 nm to 500 nm, preferably from 20 nm to 400 nm, and more preferably from 30 nm to 300 nm. The particle size distribution can be measured, for example, using a particle size distribution evaluation device such as a dynamic light scattering method or a laser diffraction method, or an electron microscope such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The volume average particle diameter is an index of the particle size variation of the pulverized material. Specifically, the D10, D50, and D90 indices can be used, with the D50 in particular being used as the particle size value.

The type of gel compound is not particularly limited. Examples of gel compounds include gel silicon compounds.

Furthermore, in the low refractive index layer (void layer), it is preferable that the silicon atoms contained therein are siloxane-bonded. Specifically, the proportion of unbonded silicon atoms (i.e., residual silanols) among all silicon atoms contained in the void layer is, for example, less than 50%, preferably 30% or less, and more preferably 15% or less.

An example of a method for forming such a low refractive index layer is described below.

This method typically includes a precursor formation step of forming a void structure on a light guide plate, which serves as a precursor for a low-refractive index layer (void layer), and a crosslinking reaction step of inducing a crosslinking reaction within the precursor after the precursor formation step. This method also includes a liquid-containing step of preparing a liquid containing microporous particles (hereinafter sometimes referred to as a "microporous particle-containing liquid" or simply "containing liquid") and a drying step of drying the liquid. In the precursor formation step, the microporous particles in the dried body are chemically bonded to form a precursor. The liquid-containing step is not particularly limited and may be, for example, a suspension containing microporous particles. The following description primarily focuses on the case where the microporous particles are a pulverized gel compound and the void layer is a porous body (preferably a silicone porous body) containing the pulverized gel compound. However, the low-refractive index layer can also be formed in a similar manner when the microporous particles are not a pulverized gel compound.

The above method results in the formation of a low-refractive-index layer (void layer) with an extremely low refractive index. The reason for this is presumed to be as follows. However, this presumption does not limit the method for forming the low-refractive-index layer.

The above-mentioned pulverized material is obtained by pulverizing a gel-like silicon compound, so the three-dimensional structure of the gel-like silicon compound before pulverization is dispersed throughout the three-dimensional basic structure. Furthermore, in the above-mentioned method, a precursor to a porous structure based on the three-dimensional basic structure is formed by applying the crushed gel-like silicon compound to a resin film. In other words, the above-mentioned method forms a new porous structure (three-dimensional basic structure) by applying the crushed material, which is different from the three-dimensional structure of the gel-like silicon compound. As a result, the finally obtained void layer can achieve a low refractive index that functions to the same extent as an air layer, for example. Furthermore, in the above-mentioned method, the crushed material is chemically bonded to each other, so the three-dimensional basic structure is fixed. Therefore, the finally obtained void layer can maintain sufficient strength and flexibility despite having a void structure.

Details of the specific configuration and formation method of the low refractive index layer are described, for example, in WO 2019/151073, the disclosure of which is incorporated herein by reference.

D. Stress Relief Layer The stress relief layer 30 may typically be made of an adhesive. The adhesive constituting the stress relief layer typically has a hardness sufficient to prevent penetration into the voids in the low refractive index layer under normal conditions. Therefore, the storage modulus of the stress relief layer at 23°C may be, for example, 0.01 MPa (0.1 x 10 ⁵ Pa) to 10 MPa. More specifically, the storage modulus of the stress relief layer at 23°C is preferably 0.02 MPa or more, more preferably 0.04 MPa or more, even more preferably 0.06 MPa or more, particularly preferably 0.08 MPa or more, and especially preferably 0.10 MPa or more. When the lower limit of the storage modulus is within this range, the adverse effect of the adhesive constituting the stress relief layer on the low refractive index layer is suppressed, and the effect of the low refractive index layer (excellent light-guiding performance) can be well maintained. On the other hand, the storage modulus of the stress relaxation layer at 23°C is preferably 5 MPa or less, more preferably 3 MPa or less, even more preferably 1 MPa or less, particularly preferably 0.70 MPa or less, particularly preferably 0.50 MPa or less, and most preferably 0.20 MPa or less. If the upper limit of the storage modulus is within this range, the stress relaxation layer will have excellent durability and a buffering function (cushioning function) against external forces, and will have a softness that can suppress peeling and/or damage of the low refractive index layer. The storage modulus can be determined by reading the value at 23°C when measured at a frequency of 1 Hz, in the range of -50°C to 150°C, at a heating rate of 5°C/min, in accordance with the method described in JIS K 7244-1 "Plastics - Testing methods for dynamic mechanical properties."

The glass transition temperature (Tg) of the stress relaxation layer is preferably 0°C or below, more preferably -100°C to -5°C, and even more preferably -90°C to -10°C. If the Tg of the stress relaxation layer is within this range, a stress relaxation layer that can achieve both excellent buffering functionality and excellent light-guiding performance can be achieved, similar to the effect achieved by setting the storage modulus within the above range.

Any suitable adhesive may be used for the stress relief layer as long as it has the above-described properties. A typical example of an adhesive is an acrylic adhesive (acrylic adhesive composition). An acrylic adhesive composition typically contains a (meth)acrylic polymer as the main component (base polymer). The (meth)acrylic polymer may be contained in the adhesive composition in an amount of, for example, 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more of the solid content of the adhesive composition. The (meth)acrylic polymer contains alkyl (meth)acrylate as a monomer unit as the main component. (Meth)acrylate refers to acrylate and/or methacrylate. Examples of the alkyl group of the alkyl (meth)acrylate include linear or branched alkyl groups having 1 to 18 carbon atoms. The average carbon number of the alkyl group is preferably 3 to 9. Monomers constituting the (meth)acrylic polymer include, in addition to alkyl (meth)acrylates, comonomers such as carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic ring-containing (meth)acrylates. The comonomer is preferably a hydroxyl group-containing monomer and/or a heterocyclic ring-containing (meth)acrylate, more preferably N-acryloylmorpholine. The acrylic pressure-sensitive adhesive composition may preferably contain a silane coupling agent and/or a crosslinking agent. Examples of silane coupling agents include epoxy group-containing silane coupling agents. Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. Details of such stress relief layers and acrylic pressure-sensitive adhesive compositions are described, for example, in Japanese Patent No. 4,140,736, the disclosure of which is incorporated herein by reference.

The thickness of the stress relief layer can vary depending on the storage modulus. That is, considering the buffering function (cushioning function) against external forces, a larger thickness is preferable; considering light-guiding performance, a smaller thickness is preferable; and the smaller the storage modulus of the stress relief layer (the softer it is), the smaller the thickness can be. Taking all of these factors into consideration, the thickness of the stress relief layer is, for example, 1 μm to 50 μm, preferably 2 μm to 40 μm, more preferably 3 μm to 30 μm, even more preferably 4 μm to 20 μm, particularly preferably 5 μm to 15 μm, and especially preferably 6 μm to 12 μm. A thickness within this range can achieve a stress relief layer that combines excellent buffering function and excellent light-guiding performance. In this case, the storage modulus of the stress relaxation layer at 23°C may be, for example, 0.08 MPa to 0.20 MPa, or may be, for example, 0.09 MPa to 0.18 MPa, or may be, for example, 0.10 MPa to 0.15 MPa, or may be, for example, 0.12 MPa to 0.14 MPa.

E. Protective Layer As described above, the tensile modulus of the protective layer 40 is 20 MPa or more, preferably 30 MPa or more, more preferably 50 MPa or more, even more preferably 100 MPa or more, and particularly preferably 300 MPa or more. On the other hand, the tensile modulus of the protective layer is preferably 10 GPa or less, more preferably 8 GPa or less, and even more preferably 6 GPa or less. If the tensile modulus of the protective layer is within this range, when the optical component is put into practical use, excellent surface protection performance can be imparted and damage to the low refractive index layer can be suppressed.

The Tg of the protective layer is preferably 20°C or higher, more preferably 40°C or higher, even more preferably 60°C or higher, and particularly preferably 70°C or higher. On the other hand, the Tg of the protective layer can be, for example, 250°C or lower. If the Tg of the protective layer is within this range, similar to the effect achieved by setting the tensile modulus within the above range, excellent surface protection performance can be imparted and damage to the low refractive index layer can be suppressed when the optical component is put into practical use.

The protective layer is composed of any appropriate resin film as long as it satisfies the above-mentioned characteristics. Examples of materials for forming the resin film include (meth)acrylic resins, cellulose-based resins such as diacetyl cellulose and triacetyl cellulose, cycloolefin-based resins such as norbornene-based resins, olefin-based resins such as polypropylene, polyester-based resins such as polyethylene terephthalate-based resins, polyamide-based resins, polycarbonate-based resins, and copolymer resins of these. (Meth)acrylic resins or polyester-based resins are preferred. Note that "(meth)acrylic resin" refers to acrylic resins and/or methacrylic resins.

The thickness of the protective layer can be, for example, 3 μm to 200 μm. A protective layer thickness within this range not only enables the optical component to be made thinner, but also provides excellent surface protection and suppresses damage to the low refractive index layer when the optical component is put to practical use. Furthermore, as described below, the resulting optical laminate (intermediate) can be given strength appropriate for producing optical components as final products. The thickness of the protective layer can vary depending on the purpose, constituent materials, etc. The thickness of the protective layer can be, for example, 5 μm to 190 μm, 10 μm to 150 μm, 15 μm to 130 μm, or 20 μm to 100 μm.

A hard coat layer and/or an anti-reflection layer may be provided on the side of the protective layer opposite the stress relief layer. By providing a hard coat layer, damage to the low refractive index layer can be further suppressed. The hard coat layer preferably has a pencil hardness of H or higher, more preferably 2H or higher, and even more preferably 3H or higher. On the other hand, the pencil hardness of the hard coat layer is preferably 6H or lower, more preferably 5H or lower. The pencil hardness can be measured based on the "Pencil Hardness Test" of JIS K 5400. The thickness of the hard coat layer may be, for example, 0.5 μm to 30 μm, or may be, for example, 1 μm to 20 μm, or may be, for example, 2 μm to 15 μm. Details of the hard coat layer are described, for example, in JP 2011-237789 A and JP 2016-224443 A. The disclosures of these publications are incorporated herein by reference.

The anti-reflection layer may have any suitable configuration. Typical configurations include: (1) a single layer of a low-refractive-index layer with an optical thickness of 120 nm to 140 nm and a refractive index of approximately 1.35 to 1.55; (2) a laminate having, from the light guide plate side, a medium-refractive-index layer, a high-refractive-index layer, and a low-refractive-index layer; and (3) an alternating multilayer laminate of high-refractive-index layers and low-refractive-index layers. The thickness of such an anti-reflection layer is, for example, approximately 5 nm to 300 nm. The anti-reflection layer may be a cured layer of a non-ionizing radiation-curable resin composition. The thickness of such an anti-reflection layer may be, for example, 1.0 μm to 20 μm, or 2.0 μm to 10 μm, or 3.0 μm to 7.0 μm. Since the materials and methods for forming the anti-reflection layer are well known in the art, detailed description is omitted for all embodiments.

F. Adhesion Auxiliary Layer As described above, the adhesion auxiliary layer typically contains a silane coupling agent. Examples of silane coupling agents include acrylic silane coupling agents, amino silane coupling agents, epoxy silane coupling agents, and mercapto silane coupling agents. The silane coupling agents may be used alone or in combination of two or more. In one embodiment, the silane coupling agent includes an acrylic silane coupling agent, and may include, for example, a combination of an acrylic silane coupling agent with an amino silane coupling agent, an epoxy silane coupling agent, a mercapto silane coupling agent, or a combination thereof (another silane coupling agent). The acrylic silane coupling agent and the other silane coupling agent may each be used alone or in combination of two or more. By providing an adhesion auxiliary layer containing a silane coupling agent, even better strength can be achieved without impairing the light-guiding performance of the optical component.

Acrylic silane coupling agents are typically silane coupling agents having a (meth)acrylic group in the backbone. Examples of acrylic silane coupling agents include 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, methacryloxymethyltrimethoxysilane, methacryloxymethyltriethoxysilane, acryloxymethyltrimethoxysilane, acryloxymethyltriethoxysilane, and 3-methacryloxypropylmethyldimethoxysilane. Furthermore, many acrylic silane coupling agents are commercially available. Specific examples of commercially available products include KBM-502 and KBM-5103 manufactured by Shin-Etsu Chemical Co., Ltd. Preferred are 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropylmethyldimethoxysilane.

Examples of amino-based silane coupling agents include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-phenylaminopropyltrimethoxysilane, and 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine. Furthermore, many amino-based silane coupling agents are commercially available. Specific examples of commercially available products include KBM-903, KBE-9103, KBM-575, and KBM-6123 manufactured by Shin-Etsu Chemical Co., Ltd., and A-1102, A-1122, and A-1170 manufactured by Momentive Performance Materials Japan, Inc. Preferably, it is 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine.

Examples of epoxy-based silane coupling agents include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane. Furthermore, many epoxy-based silane coupling agents are commercially available. Specific examples of commercially available products include KBM-402 and KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd. γ-glycidoxypropylmethyldimethoxysilane is preferred.

Examples of mercapto-based silane coupling agents include gamma-mercaptopropyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane, gamma-mercaptopropylmethyldimethoxysilane, and gamma-mercaptopropylmethyldiethoxysilane. Furthermore, many mercapto-based silane coupling agents are commercially available. A specific example of a commercially available product is X-12-1056ES manufactured by Shin-Etsu Chemical Co., Ltd.

When an acrylic silane coupling agent is used in combination with another silane coupling agent, the content ratio of the acrylic silane coupling agent to the other silane coupling agent, assuming the total amount of silane coupling agents to be 100, is preferably 40/60 to 60/40, more preferably 45/55 to 55/45, even more preferably 47/53 to 53/47, and particularly preferably approximately 50/50.

The thinner the adhesion aid layer, the better, as long as it still functions to aid adhesion between the light guide plate and the low refractive index layer. This is because adverse effects on light guide performance are minimized. Specifically, the thickness of the adhesion aid layer is preferably 500 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, particularly preferably 10 nm or less, especially preferably 5 nm or less, and most preferably 4 nm or less. The thickness of the adhesion aid layer may be, for example, 0.5 nm or more, or may be, for example, 0.7 nm or more. The thickness of the adhesion aid layer may be, for example, 0.8 nm to 3.5 nm, or may be, for example, 0.9 nm to 3 nm. If the thickness of the adhesion aid layer is very small (for example, 3 nm or less), it may not be clearly recognized as a layer, as described above.

The adhesion aid layer can be formed by applying a solution of a silane coupling agent (silane compound) dissolved in an appropriate solvent (e.g., water or isopropyl alcohol) to the surface of the light guide plate, laminating a low refractive index layer, and then drying. As described above, the adhesion aid layer itself after drying (formation) does not have any adhesive or pressure-sensitive adhesive properties, but it can assist and/or promote adhesion between the light guide plate and the low refractive index layer when the applied film of the solution dries.

G. Manufacturing Method of Optical Member According to an embodiment of the present invention, a method for manufacturing the above-described optical member is provided. The manufacturing method includes the steps of forming a low refractive index layer on a first substrate to produce a first laminate; providing a stress relief layer and a second substrate, in this order, on the low refractive index layer of the first laminate to produce an optical laminate; peeling the first substrate from the optical laminate; and laminating the optical laminate from which the first substrate has been peeled and the light guide plate so that the low refractive index layer and the light guide plate are adjacent to each other. Each step will be described in detail below with reference to Figures 2A to 2E. Note that the lamination in each step may be performed by roll-to-roll or in a batch format such as roll-to-sheet or sheet-to-sheet.

2A, a low refractive index layer 20 is formed on a first substrate 60 to produce a first laminate. The low refractive index layer can be formed by applying or printing a solution or dispersion of the material for forming the low refractive index layer described in Section C above, and drying the applied or printed film.

The peel strength between the first substrate 60 and the low refractive index layer is preferably 0.5 N/25 mm or less, more preferably 0.4 N/25 mm or less, even more preferably 0.3 N/25 mm or less, particularly preferably 0.2 N/25 mm or less, and especially preferably 0.15 N/25 mm or less. Meanwhile, this peel strength may be, for example, 0.01 N/25 mm or more, or, for example, 0.02 N/25 mm or more. If the peel strength between the first substrate and the low refractive index layer is within this range, the resulting optical laminate (intermediate) will have adequate strength for producing an optical component as a final product, and the first substrate will be easily peeled off.

The first substrate may have any suitable configuration, as long as it is capable of forming a low refractive index layer and has the above-described peel strength between it and the low refractive index layer. For example, the first substrate may be a single resin film or a laminate film containing two or more resin layers. When the first substrate is a single resin film, the specific configuration is as described above in Section E regarding the protective layer.

When the first substrate is a laminate film containing two or more resin layers, the first substrate typically has, in order from the low refractive index layer side, a first resin layer and a second resin layer. The first resin layer is typically a solidified layer of a coating film of a resin solution; the second resin layer typically has the same configuration as when the first substrate is a single resin film. In one embodiment, the first resin layer contains a cycloolefin-based resin, and the second resin layer contains a polyester-based resin. This configuration can further improve the strength of the resulting optical laminate and the peelability of the first substrate.

G-2. Optical Laminate Fabrication Step Next, as shown in FIG. 2B, a stress relief layer 30 and a second substrate 40 are sequentially laminated on the low refractive index layer 20 of the first laminate to fabricate an optical laminate. The stress relief layer 30 is typically formed on any suitable substrate and then transferred to the first laminate (substantially the low refractive index layer). The second substrate 40 is bonded to the first laminate via the stress relief layer 30. Alternatively, as shown in FIG. 2C, a stress relief layer 30 may be formed on the second substrate 40 to fabricate a second laminate, and the first and second laminates may be laminated via the stress relief layer 30 to fabricate an optical laminate as shown in FIG. 2B.

In any of the above embodiments, the lamination of the stress relief layer or the second laminate onto the first laminate can preferably be performed consecutively from the production of the first laminate. In other words, the optical laminate can be produced without first winding the first laminate into a roll. This configuration can prevent scratches or contamination of the low refractive index layer when winding the first laminate into a roll, and deformation and/or damage to the low refractive index layer due to tight winding. The obtained optical laminate can be wound into a roll as needed. The rolled optical laminate can be stored and then used in the subsequent process, or it can be used in the subsequent process without storage.

G-3. First Substrate Peeling Step Next, as shown in FIG. 2D, the first substrate 60 is peeled from the optical laminate. Peeling of the first substrate can be performed by any appropriate means. As described above, the first substrate and the low refractive index layer are configured to have an appropriate peel strength, so peeling failure can be significantly suppressed.

G-4. Optical Element Fabrication Process Finally, the optical laminate from which the first substrate 60 has been peeled is laminated on the light guide plate 10 to fabricate an optical element. The optical laminate and the light guide plate may be laminated directly (not shown) or via an adhesion aid layer 50, as shown in FIG. 2E. In either case, lamination may be performed under pressure. The pressure during lamination may be, for example, 0.008 MPa to 5 MPa. When an adhesion aid layer is used, as described above, a solution of a silane coupling agent dissolved in an appropriate solvent (e.g., isopropyl alcohol, water, or a mixture thereof) is applied to the surface of the light guide plate, and the low refractive index layer is laminated and then dried. This forms an adhesion aid layer and closely laminates the light guide plate and the low refractive index layer. The drying temperature may be, for example, 35°C to 150°C; the drying time may be, for example, 0.5 minutes to 24 hours. In the resulting optical element, the second substrate 40 may function as a protective layer.

H. Optical Devices The optical members described in sections A to G above can be applied to optical devices. Accordingly, optical devices including the optical members are also encompassed within the scope of the present invention. Typical examples of optical devices include devices that display superimposed virtual visual information, such as devices for AR glasses, MR glasses, and VR glasses. Other typical examples of optical devices include devices for lighting devices and backlight units for image display devices.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples. The methods for measuring each property are as follows. Unless otherwise specified, "%" and "parts" in the examples are by weight.

(1) Refractive Index of Low Refractive Index Layer After laminating a low refractive index layer with a protective layer onto a glass light guide plate, a laser (λ=407 nm) was incident from the glass light guide plate side using a prism coupler (manufactured by Metricon), and the refractive index at 407 nm was calculated from the measured value of the total reflection angle. This was then converted into a refractive index at 550 nm from the wavelength dispersion of the low refractive index film alone, which was calculated separately using an ellipsometer (manufactured by J.A. Woollam).

(2) Strength of Optical Element The optical elements obtained in the examples and comparative examples were sampled in the form of 50 mm x 140 mm strips, and the light guide plate side was fixed to a stainless steel plate with double-sided tape. An acrylic adhesive layer (20 μm thick) was attached to a PET film (T100: manufactured by Mitsubishi Plastics Film Co., Ltd.), and a piece of adhesive tape cut to 25 mm x 100 mm was attached to the protective layer of the optical element to form a test sample. Next, this test sample was chucked in an autograph tensile tester (manufactured by Shimadzu Corporation: AG-Xplus) so that the chuck distance was 100 mm, and then a tensile test was performed at a tensile speed of 0.3 m/min. The average test force (N/25 mm) obtained after a 50 mm peel test was used as the strength of the optical element. Furthermore, the sample was subjected to 24 hours in an environment of 60°C/90% RH, after which it was measured again.

(3) Light Guiding Performance A prism was attached to the light guide plate of the optical member obtained in each of the Examples and Comparative Examples, and light from an image was incident on the light guide plate through the prism and guided into the light guide plate. A prism was also attached to the end of the light guide plate opposite to the light incident portion for the purpose of emitting light, and the image from which the light was emitted was visually confirmed and evaluated according to the following criteria.
○ (Good): No change was observed from the image when light was incident × (Poor): Image distortion and/or a decrease in brightness was observed compared to the image when light was incident

[Production Example 1] Preparation of Coating Solution for Forming Low Refractive Index Layer (1) Gelation of Silicon Compound 0.95 g of methyltrimethoxysilane (MTMS), a precursor of the silicon compound, was dissolved in 2.2 g of dimethyl sulfoxide (DMSO) to prepare Mixed Solution A. 0.5 g of a 0.01 mol/L aqueous oxalic acid solution was added to this Mixed Solution A, and the mixture was stirred at room temperature for 30 minutes to hydrolyze the MTMS, thereby producing Mixed Solution B containing tris(hydroxy)methylsilane.
To 5.5 g of DMSO, 0.38 g of 28 wt % aqueous ammonia and 0.2 g of pure water were added, and then the above mixed solution B was further added and stirred at room temperature for 15 minutes to gel the tris(hydroxy)methylsilane, thereby obtaining mixed solution C containing a gel-like silicon compound.
(2) Aging Treatment The mixed solution C containing the gel silicon compound prepared as above was incubated at 40° C. for 20 hours to carry out an aging treatment.
(3) Pulverization Next, the gel-like silicon compound aged as described above was crushed into granules of several mm to several cm in size using a spatula. Next, 40 g of isopropyl alcohol (IPA) was added to the mixed solution C, and after light stirring, the mixture was left to stand at room temperature for 6 hours, and the solvent and catalyst in the gel were decanted. The same decantation process was performed three times to replace the solvent, and mixed solution D was obtained. Next, the gel-like silicon compound in mixed solution D was subjected to a pulverization process (high-pressure media-less pulverization). The pulverization process (high-pressure media-less pulverization) was performed using a homogenizer (manufactured by SMT Corporation, product name "UH-50"), by weighing 1.85 g of the gel-like compound in mixed solution D and 1.15 g of IPA into a 5 cc screw bottle, and then pulverizing for 2 minutes at 50 W and 20 kHz.
This pulverization treatment pulverized the gel-like silicon compound in the mixed solution D, and the mixed solution D became a pulverized sol solution E. Furthermore, to 0.75 g of sol solution E, 0.062 g of a 1.5 wt % MEK (methyl ethyl ketone) solution of a photobase generator (Wako Pure Chemical Industries, Ltd.: product name WPBG266) and 0.036 g of a 5% MEK solution of bis(trimethoxysilyl)hexane were added in a ratio of 0.062 g to obtain a coating liquid for forming a low refractive index layer.

[Production Example 2] Preparation of adhesive constituting stress relaxation layer Into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 90.7 parts of butyl acrylate, 6 parts of N-acryloylmorpholine, 3 parts of acrylic acid, 0.3 parts of 2-hydroxybutyl acrylate, and 0.1 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator were charged together with 100 g of ethyl acetate, and nitrogen gas was introduced while gently stirring to replace the atmosphere with nitrogen. After that, the liquid temperature in the flask was maintained at around 55°C and a polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution. An acrylic adhesive solution was prepared by blending 0.2 parts of an isocyanate crosslinker (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd., an adduct of trimethylolpropane and tolylene diisocyanate), 0.3 parts of benzoyl peroxide (Niper BMT, manufactured by NOF Corporation), and 0.2 parts of γ-glycidoxypropyl methoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) per 100 parts of the solids content of the obtained acrylic polymer solution. The acrylic adhesive solution was then applied to one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Polyester Film Corporation, thickness: 38 μm) so that the adhesive layer would have a thickness of 10 μm after drying, and the film was dried at 150°C for 3 minutes to form an adhesive layer. The storage modulus of the obtained adhesive was 1.3 × 10 ⁵ Pa (0.13 MPa) and Tg was -60°C. This adhesive layer was used as a stress relaxation layer.

[Example 1]
A commercially available cycloolefin resin (COP) (Zeonex F52R, manufactured by Zeon Corporation) was dissolved in a mixed solvent of ethylcyclohexane and limonene (mixing ratio: 80/20) to prepare a resin solution (solids concentration: 5%). The resin solution was applied to the surface of a commercially available polyethylene terephthalate (PET) film (thickness: 50 μm) and dried to form a 2 μm-thick COP layer, resulting in a laminate film having a first resin layer (COP layer)/second resin layer (PET layer) configuration. The resulting laminate film was used as a first substrate. The low-refractive-index layer-forming coating liquid obtained in Production Example 1 was applied to the COP layer surface of the first substrate and dried to form a 2 μm-thick low-refractive-index layer. The porosity of the low-refractive-index layer was 56% by volume, and the refractive index was 1.18. Next, the stress relaxation layer (thickness: 10 μm) formed in Production Example 2 was transferred to the surface of the low-refractive-index layer. Furthermore, an acrylic film (thickness: 30 μm, tensile modulus: 3650 MPa, Tg: 100° C.) was laminated as a protective layer (second substrate) on the surface of the stress relaxation layer to obtain an optical laminate. The lamination was performed by roll-to-roll.

The first substrate was peeled off from the resulting optical laminate. Meanwhile, the low refractive index layer side of the optical laminate from which the first substrate had been peeled off was bonded to the corona-treated surface of a glass plate for a light guide plate, the surface of which had been corona-treated, via an aqueous solution (0.5%) of an amino-silane coupling agent ("KBM-903" manufactured by Shin-Etsu Chemical Co., Ltd.) that served as an adhesion aid layer. The bonding was performed under a pressure of 0.01 MPa. After bonding, the optical member was dried at 40°C for 10 hours to obtain an optical element. The thickness of the adhesion aid layer in the resulting optical element was 3 nm. The resulting optical element was subjected to the above-mentioned evaluations of "strength" and "light guide performance." The results are shown in Table 1.

[Example 2]
An optical member was produced in the same manner as in Example 1, except that the silane coupling agent was changed to an epoxy-based silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-403"). The obtained optical member was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[Example 3]
An optical member was produced in the same manner as in Example 1, except that a PET film (thickness 75 μm, tensile modulus 4000 MPa, Tg: 78° C.) was used as the protective layer (second substrate) instead of the acrylic film. The obtained optical member was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[Example 4]
An optical member was produced in the same manner as in Example 1, except that the lamination was performed via water instead of the adhesion auxiliary layer. The obtained optical member was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[Comparative Example 1]
A low refractive index layer was formed on the surface of the same protective layer (second substrate) as in Example 1 in the same manner as in Example 1. An optical member was produced in the same manner as in Example 1, except that a laminate of protective layer/low refractive index layer was used. That is, an optical member was produced in the same manner as in Example 1, except that no stress relaxation layer was provided between the protective layer and the low refractive index layer. The obtained optical member was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
An optical member was produced in the same manner as in Comparative Example 1, except that the PET film of Example 3 was used as the protective layer (second substrate). The obtained optical member was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

[Comparative Example 3]
A low refractive index layer was formed on the surface of a protective layer (second substrate) similar to that of Example 1 in the same manner as in Example 1. Furthermore, a pressure-sensitive adhesive layer similar to that of the stress relaxation layer of Example 1 was transferred to the surface of the low refractive index layer. The resulting laminate was attached to a glass plate for a light guide plate similar to that of Example 1 via the pressure-sensitive adhesive layer to obtain an optical element. The resulting optical element was subjected to the same evaluations as in Example 1. The results are shown in Table 1.

As is clear from Table 1, the examples of the present invention provide optical components having a light guide plate and a low refractive index layer, sufficient strength as a laminate, and excellent light guide performance. More specifically, by providing a stress relief layer on the side of the low refractive index layer opposite the light guide plate, the peel force between the light guide plate and the low refractive index layer is increased (resulting in increased strength as a laminate), and by not using an adhesive or pressure-sensitive adhesive to laminate the light guide plate and the low refractive index layer, excellent light guide performance can be achieved.

Optical elements according to embodiments of the present invention can be suitably used in optical devices such as devices for AR glasses, devices for MR glasses, devices for VR glasses, devices for lighting devices, and backlight units for image display devices.

10 Light guide plate 20 Low refractive index layer 30 Stress relaxation layer 40 Protective layer (second substrate)
50 Adhesion aid layer 60 First substrate 100 Optical member

Claims (10)

a light guide plate;
a low refractive index layer provided on one main surface of the light guide plate;
a stress relaxation layer having a storage modulus of 0.01 MPa to 10 MPa, which is provided on the side of the low refractive index layer opposite to the light guide plate;
a protective layer having a tensile modulus of elasticity of 20 MPa or more, which is provided on the side of the stress relaxation layer opposite to the low refractive index layer;
An optical member comprising: The optical element described in claim 1, wherein the refractive index of the low refractive index layer is 1.25 or less. The optical element described in claim 2, wherein the low refractive index layer has a thickness of 5 μm or less. The optical element described in claim 3, wherein the haze of the low refractive index layer is less than 5%. The optical element described in claim 1, wherein the low refractive index layer is laminated directly on the light guide plate. The optical element according to claim 1, wherein the stress relaxation layer has a storage modulus of 0.08 MPa to 0.20 MPa and a thickness of 5 μm to 20 μm. An optical device comprising the optical member according to any one of claims 1 to 6. The optical device according to claim 7, selected from a device for AR glasses, a device for MR glasses, a device for VR glasses, a device for a lighting device, or a backlight unit for an image display device. A method for producing an optical member according to any one of claims 1 to 6, comprising:
forming a low refractive index layer on a first substrate to prepare a first laminate;
providing a stress relaxation layer and a second substrate in this order on the low refractive index layer of the first laminate to produce an optical laminate;
peeling the first substrate from the optical laminate;
laminating the optical laminate from which the first substrate has been peeled off and a light guide plate so that the low refractive index layer and the light guide plate are adjacent to each other;
A manufacturing method comprising: The method for producing an optical member according to claim 9 , wherein the optical laminate from which the first substrate has been peeled is directly laminated on a light guide plate.