Laminated optical member, and optical device

Abstract

This laminated optical member comprises, in the following order, an optical element, a low refractive index layer having a refractive index of 1.25 or less, and a light-absorbing layer that absorbs light from a light source.

Description

Laminated optical member and optical device

[0001] The present disclosure relates to a laminated optical member and an optical device.

[0002] Telephoto camera modules generally have a relatively long focal length and are ideal for capturing distant landscapes and subjects. In recent years, there has been a demand for ultra-telephoto camera modules to be installed in compact electronic devices such as smartphones, tablets, pads, and wearable devices.

[0003] To achieve super telephoto photography, it is generally necessary to increase the optical path length. However, in compact electronic devices, it is difficult to secure the space necessary for a long optical path length. Therefore, a folded optical system called a periscope lens is used to increase the optical path length and reduce the thickness of the electronic device to reduce its size (see, for example, Patent Document 1).

[0004] Periscope lenses use optical elements such as prisms to refract light by 90 degrees, allowing the lens and image sensor to be positioned at a right angle rather than horizontally, enabling high-magnification optical zoom even in thin electronic devices such as smartphones.

[0005] However, in order to totally reflect light inside an optical element, it is necessary to dispose a light-reflecting layer on the reflecting surface of the optical element. In order to dispose a light-reflecting layer on the reflecting surface of an optical element, an adhesive layer is generally disposed between the optical element and the light-reflecting layer and they are bonded together. However, there is a problem in that light passing through the adhesive layer reduces the total reflectance at the reflecting surface of the optical element.

[0006] On the other hand, it has been proposed to improve the light utilization efficiency of optical members by laminating a light guide plate and a reflector with a low refractive index layer interposed therebetween (see Patent Document 2).

[0007] U.S. Patent No. 11,762,174 and U.S. Patent No. 7,425,857

[0008] The present disclosure aims to solve the above-mentioned problems of the prior art and to provide a laminated optical component that can be used on a reflective surface, has excellent reflectance on the reflective surface, and can prevent stray light.

[0009] The present disclosure provides a laminated optical member having, in this order, an optical element, a low refractive index layer having a refractive index of 1.25 or less, and a light absorbing layer that absorbs light from a light source.

[0010] According to the present disclosure, it is possible to provide a laminated optical component that solves the above-mentioned problems of the prior art, can be used on a reflective surface, has excellent reflectance on the reflective surface, and can prevent stray light.

[0011] FIG. 1 is a schematic cross-sectional view showing an example of a laminated optical member according to a first embodiment of the present disclosure. FIG. 2A is a schematic cross-sectional view showing an example of a laminated optical member according to a second embodiment of the present disclosure. FIG. 2B is a schematic cross-sectional view showing another example of a laminated optical member according to the second embodiment of the present disclosure. FIG. 3 is a schematic cross-sectional view showing an example of a laminated optical member according to a third embodiment of the present disclosure. FIG. 4 is a schematic cross-sectional view showing an example of a laminated optical member according to a fourth embodiment of the present disclosure. FIG. 5 is a schematic cross-sectional view showing an example of a laminated optical member according to a fifth embodiment of the present disclosure. FIG. 6 is a schematic cross-sectional view showing an example of a laminated optical member according to a sixth embodiment of the present disclosure. FIG. 7 is a schematic cross-sectional view showing an example of a laminated optical member according to a seventh embodiment of the present disclosure. FIG. 8 is a schematic cross-sectional view showing an example of an optical device according to an embodiment of the present disclosure. FIG. 9 is a schematic explanatory diagram showing a method for evaluating the external reflection of the laminated optical member of Example 1. FIG. 10 is a diagram showing the evaluation results of the external reflection of Example 1 and Comparative Example 1. The vertical axis represents the luminous reflectance Y (%), and the horizontal axis represents the angle of incidence (°). FIG. 11 is a schematic cross-sectional view showing the layer structure of the laminated optical member of Example 2. Fig. 12 is a schematic cross-sectional view showing the layer structure of the laminated optical member of Example 3. Fig. 13 is a schematic cross-sectional view showing the layer structure of the optical member of Comparative Example 3. Fig. 14 is a schematic explanatory diagram showing a method for evaluating the external reflection of the laminated optical member of Example 2. Fig. 15 is a diagram showing the evaluation results of the internal reflection of Examples 2 and 3 and Comparative Examples 2 and 3. The vertical axis represents specular reflectance (%), and the horizontal axis represents wavelength (nm).

[0012] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the embodiments are not limited by the following description and can be modified as appropriate within the scope of the present disclosure. Furthermore, in this disclosure, unless otherwise specified, the use of "to" to indicate a range of values ​​means that the values ​​before and after the range are included as the lower and upper limits.

[0013] Unless otherwise specified, the dimensions, materials, shapes, relative arrangements, etc. of components described in the embodiments are not intended to limit the scope of the present disclosure and are merely illustrative examples. The sizes, positional relationships, etc. of components shown in each drawing may be exaggerated for clarity. In the following description, the same names and symbols indicate the same or similar components, and detailed descriptions will be omitted as appropriate. To avoid overly complex drawings, schematic diagrams may be used in which some elements are omitted, or end views showing only the cut surface may be used as cross-sectional views.

[0014] Furthermore, in this disclosure, polygons such as rectangles, triangles, and quadrilaterals are referred to as polygons, including shapes in which the corners of the polygons have been processed, such as by rounding, chamfering, corner removal, or rounding. Shapes in which processing has been applied not only to the corners (edges of the sides) but also to the middle portions of the sides are also referred to as polygons. In other words, shapes in which partial processing has been applied while retaining the polygon as a base are included in the interpretation of "polygon" described in this disclosure.

[0015] The same applies not only to polygons, but also to words that represent specific shapes such as trapezoids, circles, and irregularities. The same also applies when dealing with the sides that form the shape. In other words, even if the corners or middle part of a side have been processed, the interpretation of "side" includes the processed part. Note that when distinguishing a "polygon" or "side" that has no processing from a processed shape, the word "strict" is added, for example, "strict quadrangle."

[0016] Furthermore, in the following description, terms indicating specific directions or positions (e.g., "upper," "lower," "X," "Y," "Z," and other terms including these terms) are used as necessary. However, the use of these terms is intended to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not unduly limit the technical scope of the present disclosure. For example, when describing the "upper surface," this does not mean that the invention must always be used facing upward. Furthermore, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components.

[0017] Furthermore, in this specification or claims, when there are multiple elements of a certain type and each element needs to be expressed separately, the elements may be distinguished by adding "first," "second," etc. to the beginning of the element.

[0018] (Laminated Optical Member) A laminated optical member according to an embodiment of the present disclosure includes, in this order, an optical element, a low refractive index layer having a refractive index of 1.25 or less, and a light absorbing layer that absorbs light from a light source. The laminated optical member according to an embodiment of the present disclosure may further include other layers as necessary.

[0019] Examples of the other layers include a pressure-sensitive adhesive layer, an undercoat layer, a substrate, etc. When the laminated optical member according to the embodiment of the present disclosure has other layers, the other layers are arranged so that the stacking order of the optical element, the low refractive index layer, and the light absorbing layer remains unchanged. For example, the other layers are arranged between the optical element and the low refractive index layer, and between the low refractive index layer and the light absorbing layer. Therefore, when the laminated optical member according to the embodiment of the present disclosure has other layers, it is preferable to arrange them so that at least one surface of the optical element and one surface of the light absorbing layer are exposed.

[0020] When the technology of Patent Document 2 is applied to a periscope lens, total reflection inside the lens is preferably achieved, and therefore, when applied to a camera module, images can be preferably obtained. However, in a configuration in which the lens and the low refractive index layer are bonded together with an adhesive layer, stray light enters, which is a problem in that good image quality cannot be obtained.

[0021] In response to this problem, the laminated optical member according to the embodiment of the present disclosure has the above-described configuration, and can be used on a reflective surface, has excellent reflectivity on the reflective surface, and can prevent stray light. Specifically, when the laminated optical member according to the embodiment of the present disclosure is applied to a periscope lens of a camera module or the like, light incident into the lens is suitably reflected by the low refractive index layer. Furthermore, the stray light is suitably absorbed by the light absorbing layer, and therefore, stray light can be prevented from entering the optical element.

[0022] [First embodiment] Fig. 1 is a schematic cross-sectional view showing an example of a laminated optical member according to a first embodiment of the present disclosure. The laminated optical member 100 according to the first embodiment has a light guide plate 10A as an optical element 10, a low refractive index layer 20, and a light absorbing layer 30. The laminated optical member 100 has a first surface 100a and a second surface 100b. The first surface 100a is one surface of the light absorbing layer 30, and the second surface 100b is one surface of the optical element. In the laminated optical member 100 according to the first embodiment, the second surface 100b can be a reflective surface.

[0023] The average thickness of the laminated optical member 100 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.3 mm to 20 mm, more preferably 0.5 mm to 15 mm, and even more preferably 0.7 mm to 10 mm.

[0024] In the present disclosure, the "thickness of the laminated optical member" refers to the total thickness from one outermost layer to the other outermost layer of the laminated optical member 100. For example, in the laminated optical member 100 according to the first embodiment, the thickness of the laminated optical member 100 is the thickness from the first surface 100a, which is one surface of the optical element 10, to the second surface 100b, which is one surface of the light absorbing layer 30. Furthermore, the "average thickness of the laminated optical member" refers to the sum of the average thicknesses of all layers in the laminated optical member 100 (total thickness).

[0025] Furthermore, in the laminated optical member 100 according to the first embodiment, the total average thickness of the low refractive index layer 20 and the light absorbing layer 30 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 μm to 500 μm, more preferably 1.1 μm to 200 μm, and even more preferably 1.2 μm to 150 μm.

[0026] <Optical Element (Light Guide Plate)> The light guide plate 10A has an end surface 10a through which light from a light source is incident, an exit surface 10b through which the incident light exits, and a light extraction pattern 10c provided on the surface opposite the exit surface 10b. That is, the light guide plate 10A is typically an edge-lit type in which light enters from the end surface 10a. More specifically, the light guide plate 10A guides light incident on the end surface 10a from the light source to the end side opposite the end surface 10a while being subjected to internal reflection and the like, and gradually emits the light from the exit surface 10b during this light guide process. The light extraction pattern 10c can contribute to reflection and the like in the light guide.

[0027] The light extraction pattern 10c may be, for example, white dots, a concave-convex shape, etc. The light extraction pattern 10c may be formed by, for example, printing such as silk printing, injection molding, laser processing, or embossing.

[0028] The light exit surface 10b is typically provided with a light exit pattern, such as a concave-convex shape.

[0029] The material constituting the light guide plate 10A is not particularly limited as long as it can efficiently guide light emitted from a light source, and can be appropriately selected from known materials, such as (meth)acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resins, polyethylene terephthalate (PET) resins, styrene resins, glass, etc. In the present disclosure, "(meth)acrylic" means "acrylic" or "methacrylic."

[0030] <Low Refractive Index Layer> In the laminated optical member 100, the low refractive index layer 20 is disposed mainly to improve the reflectance on the reflective surface.

[0031] The low refractive index layer 20 has a refractive index of 1.25 or less, preferably 1.05 to 1.25, more preferably 1.08 to 1.20, and even more preferably 1.10 to 1.18. If the refractive index of the low refractive index layer 20 exceeds 1.25, the reflectance at the reflective surface of the laminated optical member 100 decreases. On the other hand, if the refractive index is 1.25 or less, the reflectance at the reflective surface of the laminated optical member 100 can be improved.

[0032] In this disclosure, unless otherwise specified, the "refractive index" refers to the refractive index measured at a wavelength of 550 nm. In this disclosure, the refractive index is a value measured by the method described in the Examples below.

[0033] The low refractive index layer 20 preferably has voids therein. The porosity of the low refractive index layer 20 is not particularly limited, but is preferably 30 vol% to 90 vol%, more preferably 35 vol% to 90 vol%, even more preferably 40 vol% to 75 vol%, and particularly preferably 50 vol% to 70 vol%. When the porosity of the low refractive index layer 20 is 30 vol% or more, a low refractive index layer 20 with a low refractive index can be formed. Furthermore, when the porosity of the low refractive index layer 20 is 90 vol% or less, a low refractive index layer 20 with excellent strength can be formed.

[0034] In the present disclosure, the "porosity" of the low refractive index layer 20 is a value calculated based on the Lorentz-Lorenz's formula from the refractive index value measured with an ellipsometer.

[0035] In the present disclosure, the dimension of the voids (holes) in the low refractive index layer 20 refers to the diameter of the long axis of the voids (holes) out of the diameter of the long axis and the diameter of the short axis. The dimension of the voids (holes) in the low refractive index layer 20 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 2 nm or more and 500 nm or less, more preferably 5 nm or more and 500 nm or less, even more preferably 10 nm or more and 200 nm or less, and particularly preferably 20 nm or more and 100 nm or less.

[0036] In the present disclosure, the dimensions of the voids (pores) in the low refractive index layer 20 are values ​​quantified by the BET test method. Specifically, 0.1 g of the low refractive index layer 20 is placed in the capillary of a specific surface area measuring device (for example, product name: ASAP2020, manufactured by Micromeritics), and then dried under reduced pressure at room temperature (25°C ± 5°C) for 24 hours to remove gas from the void structure. Then, an adsorption isotherm is drawn by adsorbing nitrogen gas into the low refractive index layer 20, and the pore distribution is determined. This allows the void dimensions to be evaluated.

[0037] The total light transmittance of the low refractive index layer 20 is not particularly limited, but is preferably 85% to 99%, more preferably 87% to 98%, and even more preferably 89% to 97%. When the total light transmittance of the low refractive index layer 20 is 85% to 99%, excellent transparency can be ensured while maintaining the function of the low refractive index layer 20.

[0038] In the present disclosure, the total light transmittance is measured in accordance with JIS K 7136:2000 using a commercially available transmittance meter (for example, trade name: HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0039] The haze of the low refractive index layer 20 is not particularly limited, but is preferably 0.1% or more and less than 5%, and more preferably 0.2% or more and less than 3%. When the haze of the low refractive index layer 20 is 0.1% or more and less than 5%, excellent transparency can be ensured while maintaining the function of the low refractive index layer 20.

[0040] In the present disclosure, the "haze" of the low refractive index layer 20 is a value calculated as follows. The low refractive index layer 20 is cut to a size of 50 mm length x 50 mm width, and the haze is measured by setting it in a haze meter (for example, product name: HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.). The haze value is calculated by the following formula 1. [Formula 1] Haze (%) = [Diffuse transmittance (%) / Total light transmittance (%)] × 100 (%)

[0041] The average thickness of the low refractive index layer 20 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 μm or more, more preferably 0.1 μm to 5 μm, even more preferably 0.3 μm to 5 μm, and particularly preferably 0.5 μm to 3 μm. If the average thickness of the low refractive index layer 20 is less than 0.1 μm, the reflectance of the reflective surface of the laminated optical member 100 may decrease. Furthermore, if the average thickness of the low refractive index layer 20 is 5 μm or less, the laminated optical member 100 can be made thinner.

[0042] In the present disclosure, the term "average thickness" refers to the average value of thicknesses at three points arbitrarily selected from each layer. The thickness of each layer can be measured using a known film thickness measuring device (e.g., R1-205, PEACOCK (registered trademark), manufactured by Ozaki Manufacturing Co., Ltd.).

[0043] Materials that can be used to form the low refractive index layer 20 include, for example, materials described in International Publication No. 2004 / 113966, Japanese Patent Application Laid-Open No. 2013-254183, and Japanese Patent Application Laid-Open No. 2012-189802. These publications are incorporated herein by reference in their entirety. Specific examples of materials that can form the low refractive index layer 20 include silicon compounds, organic polymers, polymerizable monomers, and curable resins. These materials may be used alone or in combination of two or more. Among these, it is preferable that the material that forms the low refractive index layer 20 contains a silicon compound.

[0044] Examples of silicon compounds include silica-based compounds, hydrolyzable silanes and their partial hydrolysates and dehydration condensates, silicon compounds containing silanol groups, and activated silica obtained by contacting silicate with acid or ion exchange resin. These may be used alone or in combination of two or more.

[0045] Examples of the polymerizable monomer include (meth)acrylic monomers and styrene monomers.

[0046] Examples of the curable resin include (meth)acrylic resins, fluorine-containing resins, and urethane resins.

[0047] The low refractive index layer 20 may further contain aerogel and particles. The low refractive index layer 20 may preferably be a nanoporous layer. In the present disclosure, a nanoporous layer is a layer in which 90% or more of the micropores have a diameter of 10 －１ nm to 10 ３ This refers to the low refractive index layer 20 in the range of .lambda.

[0048] The particles are not particularly limited and any appropriate particles can be used. Specific examples of the particles include microporous particles selected from the group consisting of hollow fine particles and porous particles.

[0049] These microporous particles may be, for example, sol-gel beaded particles, nanoparticles (hollow nanosilica / nanoballoon particles), nanofibers, etc. The microporous particles preferably contain an inorganic substance. Specific examples of inorganic substances include silicon (Si), magnesium (Mg), aluminum (Al), titanium (Ti), zinc (Zn), zirconium (Zr), etc. These may be used alone or in combination of two or more.

[0050] The shape of the particles is not particularly limited, and examples thereof include spherical, plate-like, needle-like, string-like, and bunch-of-grapes shapes. Examples of string-like particles include particles in which a plurality of spherical, plate-like, or needle-like particles are strung together like beads, short fiber-like particles (for example, 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-shaped particles include particles in which a plurality of spherical, plate-like, and needle-like particles are aggregated to form a bunch-of-grapes shape. The shape of the particles can be confirmed, for example, by observation with a transmission electron microscope.

[0051] An example of a specific configuration of the low refractive index layer 20 will be described below. One embodiment of the low refractive index layer 20 is composed of one or more types of structural units that form a fine void structure, and the structural units are chemically bonded to each other via catalytic action. Examples of the shape of the structural units include particulate, fibrous, rod-like, and flat plate-like shapes. The structural units may have only one shape, or may have a combination of two or more shapes.

[0052] In another embodiment of the low refractive index layer 20, the low refractive index layer 20 is a layer of a porous body in which microporous particles are chemically bonded to each other. Such a low refractive index layer 20 can be formed, for example, by chemically bonding microporous particles to each other. In another 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 body of a gel-like silica compound.

[0053] In yet another embodiment of the low refractive index layer 20, for example, the low refractive index layer 20 is made of a fibrous material such as nanofibers, and the fibrous material is entangled to form voids to form a layer. The method for manufacturing such a low refractive index layer 20 is not particularly limited, and may be the same as that for a porous layer in which microporous particles are chemically bonded to each other, for example.

[0054] Further, as another embodiment of the low refractive index layer 20, the low refractive index layer 20 may be a layer using hollow nanoparticles or nanoclay, or a layer formed using hollow nanoballoons or magnesium fluoride. The low refractive index layer 20 may be a layer made of a single constituent material, or may be a layer made of multiple constituent materials. Furthermore, the low refractive index layer 20 may be composed of a single of the above-mentioned forms, or may be composed of a plurality of the above-mentioned forms.

[0055] In the first 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, for example, a three-dimensionally interconnected pore structure in a silicone porous body, 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 (coating film of a sol containing a pulverized gel-like silicon compound), thereby easily forming an open-cell structure. More preferably, the low refractive index layer 20 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 including 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, by providing film strength with fine pores, and providing high porosity with coarse open-cell pores, it is possible to achieve both film strength and high porosity.Such a monolithic structure can be preferably formed by controlling the pore distribution of the pore structure produced in the gel (gel silicon compound) before being crushed into silica sol particles.In addition, for example, when crushing a gel silicon compound, by controlling the particle size distribution of the crushed silica sol particles to a desired size, it is possible to form a monolithic structure.

[0056] The low refractive index layer 20 contains, for example, pulverized gel compounds, and the pulverized particles are chemically bonded to each other. The form of the chemical bond between the pulverized particles in the low refractive index layer 20 is not particularly limited, and examples thereof include cross-linking, covalent bonding, and hydrogen bonding.

[0057] The type of gel compound is not particularly limited, and examples thereof include gel silicon compounds.

[0058] Furthermore, it is preferable that the silicon atoms contained in the low refractive index layer 20 are siloxane-bonded, for example. As a specific example, the proportion of unbonded silicon atoms (i.e., residual silanols) among all silicon atoms contained in the low refractive index layer 20 is not particularly limited, but is preferably less than 50 at %, more preferably 30 at % or less, and even more preferably 15 at % or less.

[0059] <<Method of Forming Low Refractive Index Layer>> The method of forming the low refractive index layer 20 is not particularly limited and can be appropriately selected depending on the purpose. An example of a method of forming the low refractive index layer 20 on one surface of the optical element 10 will be described below.

[0060] The low refractive index layer 20 can be formed, for example, by a method including a precursor formation step of forming a void structure, which is a precursor of the low refractive index layer 20, on one surface of the optical element 10, and a crosslinking reaction step of causing a crosslinking reaction inside the precursor after the precursor formation step. The method for forming the low refractive index layer 20 may further include a low refractive index layer-forming coating liquid preparation step of preparing a liquid containing microporous particles (hereinafter, sometimes referred to as a "low refractive index layer-forming coating liquid").

[0061] In the following, the case where the microporous particles are a pulverized product of a gel compound and the low refractive index layer 20 is a porous body (preferably a silicone porous body) containing the pulverized product of the gel compound will be mainly described. However, the low refractive index layer 20 can also be formed in the same manner when the microporous particles are a material other than a pulverized product of a gel compound.

[0062] -Process for preparing coating liquid for forming low refractive index layer- The process for preparing coating liquid for forming low refractive index layer is a process for preparing a coating liquid for forming a low refractive index layer. The method for producing a coating liquid for forming a low refractive index layer is not particularly limited, but preferably includes a process for preparing a pulverized material that serves as a raw material for the microporous particles, a process for aging the pulverized material (hereinafter sometimes referred to as "aging process"), a process for pulverizing the pulverized material (hereinafter sometimes referred to as "pulverization process"), and a process for replacing the hydrophilic medium with a dispersion medium (hereinafter sometimes referred to as "replacement process"). By replacing the solvent after pulverizing the pulverized material in this way, the dispersibility of the microporous particles can be maintained.

[0063] --Process for Preparing the Crushed Material-- A method for preparing the crushed material is described, for example, in JP 2017-25277 A. The entire disclosure of this publication is incorporated herein by reference. More specifically, in the process for preparing the crushed material, the material of the microporous particles, preferably a precursor of a silicon compound, is gelled in a hydrophilic medium.

[0064] The hydrophilic medium is not particularly limited, and examples thereof include isopropyl alcohol (IPA), ethanol, methanol, butanol, acetone, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and mixtures of these hydrophilic media with water. These may be used alone or in combination of two or more. Among these, IPA, DMSO, etc. are preferred.

[0065] --Aging Treatment-- In the aging treatment, the pulverized material obtained in the treatment for preparing the pulverized material is aged. There are no particular limitations on the method for aging the pulverized material, but it is preferable to incubate the pulverized material in a hydrophilic medium at 20°C to 50°C for 10 hours or more.

[0066] --Pulverization-- In the pulverization process, the material to be pulverized after the aging process is pulverized in a hydrophilic medium, thereby preparing a sol in which microporous particles are dispersed in the hydrophilic medium.

[0067] The method of grinding the material to be ground in hydrophilic medium is not particularly limited, and can be ground by any suitable method.When the material to be ground is a gel silicon compound, preferably, high-pressure medialess grinding using homogenizer can be used.In addition, the hydrophilic medium in grinding treatment can also be the mixed medium of hydrophilic medium and water.

[0068] --Replacement Treatment-- In the replacement treatment, the hydrophilic medium contained in the sol obtained by the pulverization treatment is replaced with a dispersion medium by any appropriate method, thereby obtaining a coating liquid for forming a low refractive index layer containing microporous particles and a dispersion medium.

[0069] The solvent replacement method is not particularly limited, and examples thereof include decantation, cross-flow filtration, and dynamic filtering. These replacement methods are preferably performed multiple times. If necessary, the concentration of microporous particles may be adjusted to a desired range using a dispersion medium.

[0070] In addition, when a mixed medium of a hydrophilic medium and water is used, the mixed medium may be substituted with a hydrophilic medium, preferably an alcohol having 3 or less carbon atoms, and then the hydrophilic medium may be further substituted with a dispersion medium.

[0071] The dispersion medium in the coating liquid for forming the low refractive index layer is not particularly limited and can be appropriately selected depending on the purpose, but it preferably contains a first dispersion medium having a boiling point of less than 150° C. The boiling point of the first dispersion medium is the boiling point under 1 atmosphere.

[0072] The boiling point of the first dispersion medium is less than 150°C, preferably 80°C or higher but lower than 150°C, more preferably 80°C or higher but 130°C or lower, and even more preferably 90°C or higher but 110°C or lower. Specific examples of the first dispersion medium include alcohols such as ethanol, isopropyl alcohol, butanol, t-butanol, isobutyl alcohol, and 2-methoxyethanol (methyl cellosolve); esters such as ethyl acetate and butyl acetate; ethers such as diisopropyl ether and propylene glycol monomethyl ether; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and aromatic hydrocarbons such as toluene. These may be used alone or in combination of two or more. Among these, alcohols and ketones are preferred as the first dispersion medium, with isopropyl alcohol, isobutyl alcohol, and methyl ethyl ketone being more preferred.

[0073] The content of the first dispersion medium in the coating liquid for forming a low refractive index layer is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of being able to stably adjust the viscosity of the coating liquid for forming a low refractive index layer to a range suitable for spray coating, the content is preferably 5% by mass or more and 100% by mass or less, more preferably 30% by mass or more and 95% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less, relative to the total mass of the coating liquid for forming a low refractive index layer.

[0074] The dispersion medium in the coating liquid for forming the low refractive index layer may consist solely of the first dispersion medium, or may contain, in addition to the first dispersion medium, a second dispersion medium having a boiling point of 150° C. or higher. The boiling point of the second dispersion medium is the boiling point at 1 atmosphere.

[0075] The boiling point of the second dispersion medium is 150°C or higher, preferably 150°C or higher and 200°C or lower, more preferably 155°C or higher and 200°C or lower, and even more preferably 165°C or higher and 190°C or lower. Specific examples of the second dispersion medium include dimethyl sulfoxide (DMSO); esters such as ethylene glycol monoethyl ether acetate and ethyl lactate; ethers such as diethylene glycol ethyl methyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol butyl methyl ether, tripropylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, ethylene glycol monophenyl ether, triethylene glycol monomethyl ether, diethylene glycol dibutyl ether, triethylene glycol butyl methyl ether, polyethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and polyethylene glycol monomethyl ether. These may be used alone or in combination of two or more. Among these, dimethyl sulfoxide (DMSO) and diethylene glycol ethyl methyl ether are preferred as the second dispersion medium.

[0076] The content of the second dispersion medium in the coating liquid for forming a low refractive index layer is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of being able to stably adjust the viscosity of the coating liquid for forming a low refractive index layer to a range suitable for spray coating, the content is preferably 95% by mass or less, more preferably 5% by mass or more and 95% by mass or less, even more preferably 5% by mass or more and 70% by mass or less, and particularly preferably 40% by mass or more and 60% by mass or less, relative to the total mass of the coating liquid for forming a low refractive index layer.

[0077] -Precursor Forming Step- The precursor forming step is a step of forming a void structure, which is a precursor of the low refractive index layer 20, on one surface of the optical element 10. The precursor forming step includes coating the optical element 10 with a coating liquid for forming a low refractive index layer.

[0078] The coating method for the low refractive index layer-forming coating liquid is not particularly limited, and examples thereof include a slot die coating method, a coating method using various gravure coaters, a bar coater coating method, a kiss coater coating method, and a spray coating method using a spray coater. Among these, a coating method using a spray coater (hereinafter sometimes abbreviated as "spray coating method" or "spray coating") is preferred as the coating method for the low refractive index layer-forming coating liquid. As the spray coating method, for example, the method described in International Publication No. 2023 / 190022 can be used. This publication is incorporated herein by reference in its entirety.

[0079] The conditions for spray coating the low refractive index layer-forming coating liquid are not particularly limited, but preferably include spray coating the coating liquid onto the layer to be coated to form a coating film such that the rate of change in solid content concentration satisfies the following formula 2. Satisfying the rate of change in solid content concentration as defined by formula 2 is preferable because it stabilizes the state of the coating film of the low refractive index layer-forming coating liquid formed on the layer to be coated. This prevents the coating film surface from fluctuating due to the effects of spray coating, and also prevents the formation of large voids in the coating film. As a result, thickness unevenness of the low refractive index layer 20 can be reduced. Furthermore, the transparency of the low refractive index layer 20 can be improved. The rate of change in solid content concentration is more preferably 1.5 or more and 55 or less. [Formula 2] 1.3≦rate of change in solid content concentration≦60. In formula 2, the rate of change in solid content concentration refers to the solid content concentration in the coating film 10 seconds after spray coating relative to the solid content concentration in the low refractive index layer-forming coating liquid before spray coating.

[0080] The solids concentration in the coating liquid for forming the low refractive index layer before spray coating is not particularly limited, but is preferably 0.1 mass % or more and 6.0 mass % or less, more preferably 1.0 mass % or more and 6.0 mass % or less, and even more preferably 2.0 mass % or more and 3.5 mass % or less.

[0081] The solid content concentration in the coating film 10 seconds after spray coating is not particularly limited, but is preferably 3.7% by mass or more and 6.5% by mass or less, and more preferably 4.5% by mass or more and 6.5% by mass or less.

[0082] The solids concentration in the coating liquid for forming a low refractive index layer before spray coating and the solids concentration in the coating film 10 seconds after spray coating can be quantified, for example, by spraying the coating liquid for forming a low refractive index layer onto the layer to be coated, measuring the mass before and after drying, and then quantitating the change in mass before and after drying.

[0083] The viscosity of the coating liquid for forming the low refractive index layer before spray coating is not particularly limited, but is preferably from 0.1 mPa·s to 2,000 mPa·s, and more preferably from 1.0 mPa·s to 200 mPa·s. In the present disclosure, the viscosity of the coating liquid for forming the low refractive index layer can be measured using a rheometer (for example, manufactured by Anton-Paar).

[0084] Although there are no particular limitations on the viscosity of the coating film 10 seconds after spray coating, it is preferable to satisfy the following formula 3 in order to improve the transparency of the low refractive index layer 20 and reduce thickness unevenness of the low refractive index layer 20. [Formula 3] 0.0549e １．２ｘ Viscosity of coating film 10 seconds after spray coating ≦ 0.0549 e ３．３ｘ In the above formula 3, e represents the Napier's number, and x represents the solids concentration in the coating film 10 seconds after spray coating.

[0085] The viscosity of the coating film 10 seconds after spray coating preferably satisfies Formula 3, and is preferably from 30 mPa·s to 4,500 mPa·s, more preferably from 100 mPa·s to 4,500 mPa·s, even more preferably from 300 mPa·s to 3,000 mPa·s, still more preferably from 400 mPa·s to 1,000 mPa·s, and particularly preferably from 500 mPa·s to 700 mPa·s.

[0086] In spray coating, the distance (coating distance) between the spray head that sprays the low refractive index layer-forming coating liquid and one surface of the optical element 10 is not particularly limited and can be adjusted as appropriate, but is preferably 50 mm or more and 500 mm or less, and more preferably 100 mm or more and 300 mm or less. If the distance between the spray head and one surface of the optical element 10 is large, the rate of change in solid concentration may increase, and if the distance between the spray head and one surface of the optical element 10 is small, the rate of change in solid concentration may decrease.

[0087] In spray coating, the low refractive index layer-forming coating liquid is sprayed while the spray head moves in the direction of one surface of the optical element 10. The atomization pressure in spray coating is, for example, 100 kPa to 1,000 kPa, the application amount in spray coating is, for example, 0.1 mL / min to 20 mL / min, and the movement speed of the spray head during spraying is, for example, 1 mm / sec to 1,000 mm / sec.

[0088] As a result, a coating film that forms a void structure, which is a precursor of the low refractive index layer 20, is formed on one surface of the optical element 10.

[0089] Here, one side of the optical element 10 has been described as an example of the surface on which the low refractive index layer 20 is formed, but the layer adjacent to the low refractive index layer 20 can be selected as appropriate, and even if the layer to be coated with the low refractive index layer-forming coating liquid is changed to another layer, a coating film that forms a void structure that is a precursor to the low refractive index layer 20 can be formed in the same manner.

[0090] - Crosslinking Reaction Step - The crosslinking reaction step is a step in which a crosslinking reaction occurs inside the precursor after the precursor formation step. In the crosslinking reaction step, a crosslinking reaction occurs between multiple particles contained in the coating film. The crosslinking reaction step also dries the dispersion medium in the coating liquid for forming the low refractive index layer.

[0091] The reaction conditions for causing the crosslinking reaction are not particularly limited and can be appropriately selected depending on the purpose, but the crosslinking reaction is preferably carried out by heating, which also dries the dispersion medium in the coating liquid for forming the low refractive index layer.

[0092] The heating temperature is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 60°C or higher and 200°C or lower, more preferably 70°C or higher and 120°C or lower, and even more preferably 80°C or higher and 100°C or lower.

[0093] The heating time is not particularly limited as long as the coating film can be sufficiently dried.

[0094] According to the above method, for example, a low refractive index layer 20 having a very low refractive index is formed. The reason for this is presumed to be as follows. However, the following presumption does not limit the method for forming the low refractive index layer 20.

[0095] Since the pulverized material is a pulverized gel silicon compound, the three-dimensional structure of the gel silicon compound before pulverization is dispersed in the three-dimensional basic structure. Furthermore, in the method for forming the low refractive index layer 20, a precursor of a porous structure based on the three-dimensional basic structure is formed by coating one side of the optical element 10 with crushed gel silicon compound. In other words, according to the method for forming the low refractive index layer 20, a new porous structure (three-dimensional basic structure) is formed by coating the crushed material, which is different from the three-dimensional structure of the gel silicon compound. Therefore, the finally obtained low refractive index layer 20 can achieve a low refractive index that functions at the same level as in air, for example. Furthermore, in the method for forming the low refractive index layer 20, the crushed material is chemically bonded to each other, thereby fixing the three-dimensional basic structure. Therefore, the finally obtained low refractive index layer 20 can maintain sufficient strength and flexibility despite having a void structure.

[0096] <Light Absorbing Layer> In the laminated optical member 100, the light absorbing layer 30 is disposed mainly to prevent stray light. In the laminated optical member 100, by disposing the light absorbing layer 30 as the layer closest to the light source, stray light can be prevented.

[0097] The absorption spectrum of the light-absorbing layer 30 is not particularly limited and can be selected appropriately depending on the optical device to which the laminated optical member 100 is applied, but is preferably 380 nm to 2,500 nm. For example, when the absorption spectrum of the light-absorbing layer 30 is in the visible light region, it can be suitably applied to an optical device having an image sensor that corresponds to the visible light region. Furthermore, when the absorption spectrum of the light-absorbing layer 30 is in the near-infrared region, it can be suitably applied to an optical device having an image sensor that corresponds to the near-infrared region.

[0098] The definition of near-infrared rays varies depending on the technical field, but in an embodiment of the present disclosure, "near-infrared rays" means light containing at least light (electromagnetic waves) having a wavelength in the range of 760 nm to 2,000 nm. Also, in an embodiment of the present disclosure, "visible light" means light having a wavelength in the range of 400 nm to less than 760 nm.

[0099] The light absorbing layer 30 may be a design layer having a predetermined design or may be a solid colored layer. The light absorbing layer 30 is preferably a solid colored layer, and more preferably a black colored layer.

[0100] The total light transmittance of the light absorbing layer 30 is not particularly limited, but is preferably 0.01% or less, and more preferably 0.008% or less. The smaller the total light transmittance of the light absorbing layer 30, the more preferable it is, and there is no particular limit to the lower limit, but examples include 0.001% or more. If the total light transmittance of the light absorbing layer 30 is 0.01% or less, even better light absorption and blocking functions can be achieved.

[0101] The average thickness of the light absorbing layer 30 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.1 μm to 300 μm. When the average thickness of the light absorbing layer 30 is 0.1 μm to 300 μm, it is easy to achieve the desired total light transmittance, thereby achieving even more excellent light absorption and blocking functions.

[0102] The method for forming the light absorbing layer 30 is not particularly limited, and examples thereof include any suitable printing method using any suitable ink or paint. Specific examples of printing methods include inkjet printing, gravure printing, offset printing, silkscreen printing, and transfer printing from a transfer sheet.

[0103] The ink or paint used to form the light absorbing layer 30 is not particularly limited and can be appropriately selected depending on the purpose. For example, it may contain a binder, a colorant, and a solvent, and may further contain any appropriate additives that can be used as needed.

[0104] The binder is not particularly limited, and examples thereof include chlorinated polyolefins (e.g., chlorinated polyethylene, chlorinated polypropylene, etc.), polyester resins, urethane resins, acrylic resins, vinyl acetate resins, vinyl chloride-vinyl acetate copolymers, cellulose resins, etc. These may be used alone or in combination of two or more.

[0105] The binder may be a thermopolymerizable resin or a photopolymerizable resin. Among these, the binder is preferably a (meth)acrylic resin, and more preferably a (meth)acrylic resin containing a polyfunctional monomer (e.g., pentaerythritol triacrylate) as a copolymerization component.

[0106] The colorant is not particularly limited, and any appropriate colorant can be used depending on the purpose.Specific examples of the colorant include inorganic pigments such as titanium white, zinc white, carbon black, iron black, red iron oxide, chrome vermilion, ultramarine blue, cobalt blue, yellow lead, and titanium yellow; organic pigments or dyes such as phthalocyanine blue, indanthrene blue, isoindolinone yellow, benzidine yellow, quinacridone red, polyazo red, perylene red, and aniline black; metal pigments consisting of scaly foil flakes such as aluminum and brass; and pearlescent pigments (pearl pigments) consisting of scaly foil flakes such as titanium dioxide-coated mica and basic lead carbonate.

[0107] When the light absorbing layer 30 is to be a black layer, carbon black, iron black, or aniline black is preferably used. In this case, it is preferable to use a colorant in combination, because this allows for the formation of a colorless (i.e., pitch black) light absorbing layer 30 that absorbs visible light widely and uniformly.

[0108] When the light-absorbing layer 30 is to be a black layer, an azo compound and / or a quinone compound may be used in addition to the colorant. The colorant is not particularly limited and can be selected appropriately depending on the purpose. For example, the colorant may contain carbon black as a main component and other colorants (e.g., an azo compound and / or a quinone compound). This configuration allows for the formation of a black layer that is not colored and has excellent stability over time.

[0109] When the light absorbing layer 30 is a black layer, the content of the colorant in the ink or paint is not particularly limited, but it is preferable that the colorant be present in an amount of 1 to 200 parts by mass per 100 parts by mass of the binder. In this case, the content of carbon black in the colorant is preferably 1 to 100% by mass. By using the colorant (particularly carbon black) in such a proportion, it is possible to form a light absorbing layer 30 that has an extremely low total light transmittance and excellent stability over time.

[0110] [Second embodiment] Fig. 2A is a schematic cross-sectional view showing an example of a laminated optical member according to a second embodiment of the present disclosure. Fig. 2B is a schematic cross-sectional view showing another example of a laminated optical member according to the second embodiment of the present disclosure. The laminated optical member 100 according to the second embodiment has a prism 10B as the optical element 10, a low refractive index layer 20, and a light absorbing layer 30. The laminated optical member 100 according to the second embodiment has the same configuration as the laminated optical member 100 according to the first embodiment, except that the optical element 10 is a prism 10B.

[0111] <Optical Element (Prism)> The shape of the prism 10B is not particularly limited as long as it does not impair the effects of the present disclosure, and any appropriate shape can be selected as appropriate. The cross-sectional shape of the prism 10B in the stacking direction of the laminated optical member 100, i.e., in the Y-axis direction, may be a polygonal shape such as a triangle or a rectangle. In addition, one or both slopes of the triangle may have multiple flat surfaces with different slope angles.

[0112] When the cross section of prism 10B in the Y-axis direction is triangular, the cross section may be asymmetric with respect to a line passing through the apex of prism 10B in the stacking direction of laminated optical member 100 (for example, a scalene triangle), or symmetric with respect to the line (for example, an isosceles triangle). Furthermore, the apex of prism 10B may be chamfered and curved, or may be cut so that the tip is flat, resulting in a trapezoidal cross section.

[0113] The material for prism 10B is not particularly limited as long as it can efficiently guide the light irradiated from the light source, and can be appropriately selected from among known materials, such as (meth)acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resins, polyethylene terephthalate (PET) resins, styrene resins, and glass.

[0114] 3 is a schematic cross-sectional view showing an example of a laminated optical member according to a third embodiment of the present disclosure. The laminated optical member 100 according to the third embodiment has, in this order, a light guide plate 10A as an optical element 10, a low refractive index layer 20, a pressure-sensitive adhesive layer 40, and a light absorbing layer 30. The laminated optical member 100 according to the third embodiment has the same configuration as the laminated optical member 100 according to the first embodiment, except for the pressure-sensitive adhesive layer 40.

[0115] In the laminated optical member 100 according to the third embodiment, the light guide plate 10A can be replaced with the prism 10B in the laminated optical member 100 according to the second embodiment.

[0116] <Adhesive Layer> The adhesive layer 40 is disposed to bond the two layers together. In Fig. 3, the adhesive layer 40 is disposed between the low refractive index layer 20 and the light absorbing layer 30, but the adhesive layer 40 may be disposed between the optical element 10 and the low refractive index layer 20.

[0117] The pressure-sensitive adhesive layer 40 preferably has a hardness such that the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 40 does not penetrate into the voids in the low refractive index layer 20 under normal conditions. Therefore, the storage modulus of the pressure-sensitive adhesive layer 40 at 23° C. is not particularly limited, but is preferably 0.2×10 ５ Pa or more 5.0×10 ７ Pa or less is preferable, and 0.4 × 10 ５ Pa or more 4.0×10 ７ Pa or less is more preferable, and 0.6×10 ５ Pa or more 3.0×10 ７ Pa or less is more preferable, and 0.8×10 ５ Pa or more 2.0×10 ７ Pa or less is even more preferable, and 1.0 × 10 ５ Pa or more 1.0×10 ７ The storage modulus of the pressure-sensitive adhesive layer 40 at 23° C. is particularly preferably 0.2×10 Pa or less. ５ When the pressure-sensitive adhesive layer 40 has a storage modulus of 5.0×10 Pa or more, the pressure-sensitive adhesive layer 40 has a hardness that is such that the pressure-sensitive adhesive layer 40 does not penetrate into voids in the low refractive index layer 20. In addition, the pressure-sensitive adhesive layer 40 has a storage modulus of 5.0×10 at 23° C. ７If the elastic modulus is equal to or less than Pa, the optical element 10 has a buffering function (cushioning function) against external forces, and has a softness that can prevent damage to other layers such as the optical element 10 and the low refractive index layer 20 .

[0118] In the present disclosure, the storage modulus of the pressure-sensitive adhesive layer 40 at 23°C is 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 temperature rise rate of 5°C / min in accordance with the method described in JIS K 7244-1:1988 "Plastics - Test methods for dynamic mechanical properties."

[0119] Any appropriate adhesive may be used as the adhesive constituting the adhesive layer 40 as long as it has the above-described properties. Examples of the adhesive include a (meth)acrylic adhesive composition. The (meth)acrylic adhesive composition preferably contains a (meth)acrylic polymer as a base polymer.

[0120] The content of the (meth)acrylic polymer is not particularly limited, but is preferably 50 mass % or more, more preferably 70 mass % or more, and even more preferably 90 mass % or more, of the solid content of the (meth)acrylic pressure-sensitive adhesive composition.

[0121] The (meth)acrylic polymer contains alkyl(meth)acrylate as a monomer unit as a main component. Examples of the alkyl group of the alkyl(meth)acrylate include linear or branched alkyl groups having 1 to 18 carbon atoms. The average number of carbon atoms in the alkyl group is not particularly limited, but is preferably 3 to 9. In the present disclosure, "(meth)acrylate" means "acrylate" or "methacrylate."

[0122] The monomer constituting the (meth)acrylic polymer may contain, in addition to alkyl (meth)acrylate, a comonomer such as a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an amide group-containing monomer, an aromatic ring-containing (meth)acrylate, or a heterocycle-containing (meth)acrylate. These may be used alone or in combination of two or more. Among these, the comonomer is preferably a hydroxyl group-containing monomer and / or a heterocycle-containing (meth)acrylate, and more preferably N-acryloylmorpholine.

[0123] The (meth)acrylic pressure-sensitive adhesive composition may further contain a silane coupling agent and / or a crosslinking agent. The silane coupling agent is not particularly limited, and examples thereof include epoxy group-containing silane coupling agents. The crosslinking agent is not particularly limited, and examples thereof include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. These may be used alone or in combination of two or more.

[0124] Details of such a pressure-sensitive adhesive layer 40 and an acrylic pressure-sensitive adhesive composition are described in, for example, Japanese Patent No. 4140736, which is incorporated herein by reference in its entirety.

[0125] The method for forming the pressure-sensitive adhesive layer 40 is not particularly limited and can be appropriately selected from known methods. Examples include a method in which a pressure-sensitive adhesive composition, preferably a (meth)acrylic pressure-sensitive adhesive composition, containing monomers of materials constituting the pressure-sensitive adhesive layer 40, and further a silane coupling agent and / or a crosslinking agent, a polymerization solvent, etc., is applied to a separator that has been subjected to a release treatment, the polymerization solvent, etc. is dried and removed to form the pressure-sensitive adhesive layer 40, and then the pressure-sensitive adhesive layer 40 is transferred to a layer adjacent to the pressure-sensitive adhesive layer 40 (e.g., the low refractive index layer 20, the light absorbing layer 30, the optical element 10, etc.); and a method in which a pressure-sensitive adhesive composition, preferably a (meth)acrylic pressure-sensitive adhesive composition, is applied to a layer adjacent to the pressure-sensitive adhesive layer 40 (e.g., the low refractive index layer 20, the light absorbing layer 30, the optical element 10, etc.), the polymerization solvent, etc. is dried and removed to form the pressure-sensitive adhesive layer 40 on the adjacent layer.

[0126] An anchor layer may be formed on the surface of the layer adjacent to the pressure-sensitive adhesive layer 40 on which the pressure-sensitive adhesive layer 40 is to be formed, or the pressure-sensitive adhesive layer 40 may be formed after various adhesion-facilitating treatments such as corona treatment and plasma treatment. The surface of the pressure-sensitive adhesive layer 40 may also be subjected to adhesion-facilitating treatment.

[0127] Examples of methods for applying the adhesive composition when forming the adhesive layer 40 include a coating method using a slot die, a coating method using various gravure coaters, a coating method using a bar coater, a coating method using a kiss coater, and a coating method by spraying using a spray coater or the like.

[0128] The constituent material of the separator is not particularly limited, and examples thereof include plastic films, porous materials such as paper, cloth, and nonwoven fabrics, nets, foam sheets, metal foils, and appropriately selected thin sheets such as laminates thereof, etc. Among these, plastic films are preferably used as the constituent material of the separator because of their excellent surface smoothness.

[0129] The plastic film is not particularly limited as long as it is a film that can protect the adhesive layer 40, and examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.

[0130] The average thickness of the separator is not particularly limited, but is preferably 5 μm to 200 μm, and more preferably 5 μm to 100 μm. The separator may be subjected to a release and antifouling treatment, an antistatic treatment, or the like, as necessary. Examples of release and antifouling treatments include treatment with a silicone-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based release agent; treatment with silica powder, or the like. Examples of antistatic treatments include coating-type, kneading-type, and vapor deposition-type treatments. In particular, by appropriately performing a release treatment on the surface of the separator, such as treatment with a silicone-based release agent, treatment with a long-chain alkyl-based release agent, or treatment with a fluorine-based release agent, the releasability from the pressure-sensitive adhesive layer 40 can be further improved.

[0131] The average thickness of the pressure-sensitive adhesive layer 40 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 3 μm to 30 μm, and more preferably 5 μm to 20 μm. When the average thickness of the pressure-sensitive adhesive layer 40 is 3 μm to 30 μm, damage to other layers such as the optical element 10 and the low refractive index layer 20 can be suppressed.

[0132] 4 is a schematic cross-sectional view showing an example of a laminated optical member according to a fourth embodiment of the present disclosure. The laminated optical member 100 according to the fourth embodiment has, in this order, an optical element 10, an undercoat layer 50, a low refractive index layer 20, and a light absorbing layer 30. The laminated optical member 100 according to the fourth embodiment has the same configuration as the laminated optical member 100 according to the first embodiment, except for having the undercoat layer 50.

[0133] In the laminated optical member 100 according to the fourth embodiment, the light guide plate 10A can be replaced with the prism 10B in the laminated optical member 100 according to the second embodiment.

[0134] <Undercoat Layer> The undercoat layer 50 is disposed to improve adhesion between the optical element 10 and the low refractive index layer 20. Therefore, the undercoat layer 50 is suitably disposed between the optical element 10 and the low refractive index layer 20.

[0135] The undercoat layer 50 can be formed by applying a primer. The primer material is preferably one that exhibits good adhesion to both the optical element 10 and the low refractive index layer 20 and forms a film with excellent cohesive strength, and examples of such a primer include a silane coupling agent and a polymer such as urethane. Among these, a primer is preferably one prepared by hydrolyzing a silane coupling agent to form an aqueous solution, and then mixing the solution with an organic solvent that is optionally compatible with water.

[0136] The silane coupling agent is not particularly limited, and examples thereof include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-phenyl-aminopropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane. These may be used alone or in combination of two or more. Among these, 3-aminopropyltrimethoxysilane is preferred. Furthermore, examples of commercially available products include those under the trade name "KBM-903" (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0137] The method for applying the primer when forming the primer layer 50 is not particularly limited, and examples thereof include a coating method using a slot die, a coating method using various gravure coaters, a coating method using a bar coater, a coating method using a kiss coater, and a coating method by spraying using a spray coater or the like.

[0138] The average thickness of the undercoat layer 50 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 nm to 50 nm, more preferably 2 nm to 30 nm, and even more preferably 3 nm to 20 nm.

[0139] 5 is a schematic cross-sectional view showing an example of a laminated optical member according to a fifth embodiment of the present disclosure. The laminated optical member 100 according to the fifth embodiment has, in this order, an optical element 10, an undercoat layer 50, a low-refractive-index layer 20, a pressure-sensitive adhesive layer 40, and a light-absorbing layer 30. The laminated optical member 100 according to the fifth embodiment has the same configuration as the laminated optical member 100 according to the first embodiment, except for the inclusion of the undercoat layer 50 and the pressure-sensitive adhesive layer 40.

[0140] The undercoat layer 50 is as described in the laminated optical member 100 according to the fourth embodiment. The pressure-sensitive adhesive layer 40 is as described in the laminated optical member 100 according to the third embodiment.

[0141] In the laminated optical member 100 according to the fifth embodiment, the light guide plate 10A can be replaced with the prism 10B in the laminated optical member 100 according to the second embodiment.

[0142] 6 is a schematic cross-sectional view showing an example of a laminated optical member according to a sixth embodiment of the present disclosure. The laminated optical member 100 according to the sixth embodiment has, in this order, an optical element 10, an undercoat layer 50, a low refractive index layer 20, a substrate 60, a pressure-sensitive adhesive layer 40, and a light-absorbing layer 30. The laminated optical member 100 according to the sixth embodiment has the same configuration as the laminated optical member 100 according to the fifth embodiment, except for having the substrate 60.

[0143] In the laminated optical member 100 according to the sixth embodiment, the light guide plate 10A can be replaced with the prism 10B in the laminated optical member 100 according to the second embodiment.

[0144] <Substrate> The substrate 60 is disposed mainly to improve the strength of the laminated optical member 100. The substrate 60 is preferably disposed between the low refractive index layer 20 and the light absorbing layer 30. In this case, it is preferable to dispose a pressure-sensitive adhesive layer 40 between the substrate 60 and the light absorbing layer 30.

[0145] The Young's modulus of the substrate 60 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 2 GPa to 10 GPa, more preferably 2.5 GPa to 9 GPa, and even more preferably 3 GPa to 8 GPa. When the Young's modulus of the substrate is 2 GPa to 10 GPa, damage to the optical element 10 and other layers such as the low refractive index layer 20 can be suppressed.

[0146] The material of the substrate 60 is not particularly limited, but is preferably a resin film. Examples of materials for forming the resin film include cellulose-based resins such as (meth)acrylic resins, diacetyl cellulose, and triacetyl cellulose; cycloolefin-based resins such as norbornene-based resins; olefin-based resins such as polypropylene; ester-based resins such as polyethylene terephthalate-based resins; polyamide-based resins; polycarbonate-based resins; and copolymer resins thereof. In this disclosure, "(meth)acrylic resin" means "acrylic resin" or "methacrylic resin."

[0147] The moisture permeability of the substrate 60 is not particularly limited and can be appropriately selected depending on the purpose. ２ / 24hr~1,000g / m ２ / 24hr is preferred, and 0.5g / m ２ / 24hr~800g / m ２ / 24hr is more preferable, and 1g / m ２ / 24hr~500g / m ２ / 24 hr is more preferable. ２ / 24hr~1,000g / m ２ If the time is 24 hours, damage to the optical element 10 and other layers such as the low refractive index layer 20 can be further suppressed.

[0148] The average thickness of the substrate 60 is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 20 μm to 50 μm, and more preferably 25 μm to 40 μm. When the average thickness of the substrate 60 is 20 μm to 50 μm, damage to the optical element 10 and other layers such as the low refractive index layer 20 can be suppressed.

[0149] Seventh Embodiment Fig. 7 is a schematic cross-sectional view showing an example of a laminated optical member according to a seventh embodiment of the present disclosure. The laminated optical member 100 according to the seventh embodiment has an optical element 10, a low refractive index layer 20, a light absorbing layer 30, an incident portion 70, and an exit portion 80. The laminated optical member 100 according to the seventh embodiment is formed by laminating the low refractive index layer 20 and the light absorbing layer 30 in this order around the periphery of the optical element 10. The laminated optical member 100 according to the seventh embodiment has the same configuration as the laminated optical member 100 according to the first embodiment, except for the shape of the optical element 10, the arrangement of the low refractive index layer 20 and the light absorbing layer 30 around the periphery of the optical element 10, and the inclusion of the incident portion 70 and the exit portion 80.

[0150] In the laminated optical member 100 according to the seventh embodiment, the optical element 10 may be a light guide plate 10A or a prism 10B. The shape of the optical element 10 in Fig. 7 is an example and is not limited to a quadrangle, and may be a rectangle, a triangle, another polygon, or the like, as long as the effects of the present disclosure are achieved.

[0151] The laminated optical members 100 according to the second to sixth embodiments may also have the shape of the laminated optical member 100 according to the seventh embodiment.

[0152] In the laminated optical member 100 according to the seventh embodiment, light L from the light source enters the optical element 10 through the incident portion 70, is reflected in order by the first inner surface 20-1, the second inner surface 20-2, and the third inner surface 20-3 of the low refractive index layer 20, and is emitted from the exit portion 80. On the other hand, light L from the light source irradiated onto the light absorbing layer 30 is absorbed by the light absorbing layer 30, and therefore stray light within the optical element 10 can be prevented.

[0153] <Incident Portion> The incident portion 70 is a member into which the light L from the light source is incident. The shape of the incident portion 70 is not particularly limited as long as it can allow the light L to be incident on the optical element 10, and can be appropriately selected depending on the purpose. Examples of the shape of the incident portion 70 include polygonal shapes such as a triangular shape and a quadrangular shape.

[0154] The dimensions of the incident section 70 are not particularly limited, and can be selected appropriately depending on other components when applying the laminated optical element 100, for example, when applying it to the optical device of the present disclosure described below, such as the dimensions of the multiple lenses, the dimensions of the image sensor, the width of the optical path, etc., but from the standpoint of preventing stray light, it is preferable that 10% or more of the area of ​​the light entrance surface of the incident section 70 is covered, more preferably 30% or more, and even more preferably 50% or more.

[0155] Furthermore, in a cross-sectional view of the stacking direction of the laminated optical element 100 of the incident portion 70, i.e., in the XY plane, the length of the laminated optical element 100 of the incident portion 70 in the stacking direction, i.e., the length in the Y-axis direction, may be the same as the total thickness of the average thickness of the low refractive index layer 20 and the light absorbing layer 30, or may be shorter than the total thickness of the average thickness of the low refractive index layer 20 and the light absorbing layer 30.

[0156] The material constituting the incident portion 70 is not particularly limited as long as it can efficiently admit light irradiated from the light source, and can be appropriately selected from among known materials, such as (meth)acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resins, polyethylene terephthalate (PET) resins, styrene resins, and glass.

[0157] <Emitting section> The emitting section 80 is a member from which the light L incident on the optical element 10 is emitted. The shape of the emitting section 80 is not particularly limited as long as it can emit the light L incident on the optical element 10, and can be appropriately selected depending on the purpose, and examples thereof include polygonal shapes such as a triangular shape and a quadrangular shape.

[0158] The dimensions of the exit section 80 are not particularly limited, and can be selected appropriately depending on other components when applying the laminated optical element 100, for example, when applying it to the optical device of the present disclosure described below, such as the dimensions of the multiple lenses, the dimensions of the image sensor, the width of the optical path, etc., but from the standpoint of preventing stray light, it is preferable that 10% or more of the area of ​​the exit surface of the exit section 80 is covered, more preferably 30% or more, and even more preferably 50% or more.

[0159] Furthermore, in a cross-sectional view of the stacking direction of the laminated optical element 100 of the exit portion 80, i.e., in the XY plane, the length of the laminated optical element 100 of the exit portion 80 in the stacking direction, i.e., the length in the Y-axis direction, may be the same as the total thickness of the average thickness of the low refractive index layer 20 and the average thickness of the light absorbing layer 30, or may be shorter than the total thickness of the average thickness of the low refractive index layer 20 and the average thickness of the light absorbing layer 30.

[0160] The material constituting the emission section 80 is not particularly limited as long as it can efficiently allow light irradiated from the light source to enter, and can be appropriately selected from among known materials, such as (meth)acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resins, polyethylene terephthalate (PET) resins, styrene resins, and glass.

[0161] <Applications> The laminated optical member according to the embodiment of the present disclosure can be used on a reflective surface, and because it has excellent reflectance on the reflective surface and can prevent stray light, it can be suitably used as an optical member for an optical filter, an optical member for an imaging device, an optical member for an optical sensor device, etc. Specific examples include optical members for camera modules, televisions, car navigation systems, personal digital assistants, video game consoles, portable game consoles, fingerprint authentication systems, digital music players, etc.

[0162] The laminated optical member according to the embodiment of the present disclosure is particularly useful as an optical member for a camera module having a telephoto function, such as a digital still camera, a smartphone camera, a mobile phone camera, a digital video camera, a wearable device camera, a PC camera, a surveillance camera, or an automotive camera.

[0163] (Optical Device) The optical device according to the embodiment of the present disclosure includes a plurality of lenses, an image sensor, and a laminated optical member according to the embodiment of the present disclosure. The optical device according to the embodiment of the present disclosure may further include other members as necessary.

[0164] 8 is a schematic cross-sectional view illustrating an example of an optical device 200 according to an embodiment of the present disclosure. The optical device 200 is a camera module, and includes a plurality of lenses 90, an image sensor 95, and a laminated optical member 100.

[0165] Light L from the subject passes through multiple lenses 90 consisting of a first lens 90a, a second lens 90b, a third lens 90c, and a fourth lens 90d, passes through the laminated optical element 100, and is then received by the image sensor 95 to be photographed.

[0166] Although four lenses 90 are shown in FIG. 8, the number of lenses 90 is not particularly limited and can be selected appropriately depending on the purpose.

[0167] The image sensor 95 is not particularly limited and can be appropriately selected from known image sensors.

[0168] Optical devices according to embodiments of the present disclosure may be suitable for use in, for example, handheld devices, in-vehicle devices, wearable devices, computing devices, other processing devices connected to a wireless modem, etc. Specific examples of optical devices according to embodiments of the present disclosure include cellular phones, smartphones, personal digital assistant (PDA) computers, tablet computers, laptop computers, video cameras, video recorders, cameras, smart watches, smart bracelets, in-vehicle computers, and other electronic devices with imaging capabilities.

[0169] The optical device according to the embodiment of the present disclosure can be used on a reflective surface, has excellent reflectivity on the reflective surface, and has a laminated optical component according to the embodiment of the present disclosure that can prevent stray light. Therefore, when applied to a camera module in particular, the optical device can be made smaller and thinner, and high-quality images can be obtained.

[0170] The present disclosure will be specifically described below with reference to Preparation Examples, Examples, and Comparative Examples, but the present disclosure is not limited to these Preparation Examples, Examples, and Comparative Examples. In the Preparation Examples, Examples, and Comparative Examples, unless otherwise specified, "%" indicates "% by mass" and "parts" indicates "parts by mass."

[0171] [Method for Measuring the Refractive Index of the Low Refractive Index Layer] In Examples 1 to 3 below, the refractive index of the low refractive index layer was measured by the following method. A coating solution for forming a low refractive index layer (Preparation Example 1) was spray-coated onto an acrylic film using the method and conditions described in Example 1. The coating was then treated at 100°C for 1 minute and dried to form a low refractive index layer with an average thickness of 2.0 μm. This was cut to a size of 50 mm length x 50 mm width. Separately, the pressure-sensitive adhesive layer formed in Preparation Example 2 was transferred to one side of a glass plate (glass type: S-BSL7, product number: 516641, manufactured by Ohara Inc., average thickness: 2 mm), and the side of the pressure-sensitive adhesive layer opposite the side with the glass plate was laminated to the side of the low refractive index layer opposite the side with the acrylic film. A region approximately 20 mm in diameter in the center of the exposed surface of the glass plate was filled in with black marker to create a sample that would not reflect light on the back surface of the glass plate. The prepared sample was set in an ellipsometer (trade name: VASE (registered trademark), manufactured by J.A. Woollam Japan), and the refractive index was measured at a wavelength of 550 nm and an incident angle of 50° to 80°.

[0172] [Method for measuring porosity of low refractive index layer] In the method for measuring the refractive index of the low refractive index layer, the refractive index of the low refractive index layer in Examples 1 to 3 below was calculated from the refractive index value measured with an ellipsometer based on the Lorentz-Lorenz formula.

[0173] [Method for measuring solids concentration of low refractive index layer-forming coating liquid] In the following Examples 1 to 3, the solids concentration of the low refractive index layer-forming coating liquid before application was calculated from the amount charged. Furthermore, in the following Examples 1 to 3, the solids concentration in the coating film 10 seconds after spray application of the low refractive index layer-forming coating liquid was taken as the solids concentration at application, and was calculated using the following formula 4. [Formula 4] Solids concentration at application (mass %) = (A / B) x 100 = {(C-D) / (E-D)} x 100 In the formula 4, A to E represent the following. A: solid content mass of the coating liquid for forming a low refractive index layer applied to the target layer B: total mass of the coating liquid for forming a low refractive index layer applied to the target layer C: sum of masses of the target layer and coating film after drying (meaning the mass after continuing to dry the coating film on the target layer at 90°C until there is no change in mass due to solvent evaporation) D: mass of the target layer before application of the coating liquid for forming a low refractive index layer E: sum of masses of the target layer and coating film 10 seconds after spray application Target layer in A to E: acrylic film in measurement of the refractive index of the low refractive index layer 20, undercoat layer 50 in Example 1, and substrate 60 in Examples 2 to 4

[0174] The change ratio between the solid content concentration of the low refractive index layer-forming coating liquid before application and the solid content concentration of the low refractive index layer-forming coating liquid at the time of application was calculated using the following formula 5: [Formula 5] Change ratio = solid content concentration at application (mass%) / solid content concentration before application (mass%)

[0175] [Method for measuring viscosity of coating liquid for forming low refractive index layer] In the following Examples 1 to 3, the viscosity of the coating liquid for forming the low refractive index layer before and after application was measured using a rheometer (manufactured by Anton-Paar).

[0176] (Preparation Example 1: Preparation of Coating Liquid for Forming Low Refractive Index Layer) <Gelling of Silicon Compound> 0.95 g of methyltrimethoxysilane (MTMS), a precursor of a silicon compound, was dissolved in 2.2 g of dimethyl sulfoxide (DMSO) to prepare Mixed Liquid A. 0.5 g of a 0.01 mol / L aqueous oxalic acid solution was added to this Mixed Liquid A, and the mixture was stirred at room temperature (25°C ± 5°C) for 30 minutes to hydrolyze the MTMS, thereby preparing Mixed Liquid B containing tris(hydroxy)methylsilane.

[0177] To 5.5 g of DMSO, 0.38 g of 28% aqueous ammonia and 0.2 g of pure water were added, and then mixed solution B was further added and stirred at room temperature for 15 minutes to gel tris(hydroxy)methylsilane, thereby obtaining mixed solution C containing a gel-like silicon compound.

[0178] <Aging Treatment> The prepared mixed solution C containing the gel silicon compound was incubated at 40° C. for 20 hours to carry out an aging treatment.

[0179] <Crushing Treatment> The gel-like silicon compound in the aged mixed solution C 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 (25°C ± 5°C) for 6 hours to decant the solvent and catalyst in the gel. The same decantation treatment was repeated three times to replace the solvent, and mixed solution D was obtained.

[0180] Next, the gel-like silicon compound in mixed solution D was subjected to a pulverization treatment (high-pressure media-less pulverization). The pulverization treatment (high-pressure media-less pulverization) was carried out using a homogenizer (trade name: UH-50, manufactured by SMT Corporation) by weighing 1.85 g of the gel-like compound in mixed solution D and 1.15 g of IPA into a 5 mL screw bottle, and then pulverizing for 2 minutes under conditions of 50 W and 20 kHz. By this pulverization treatment, the gel-like silicon compound in mixed solution D was pulverized, and mixed solution D became a pulverized sol solution E.

[0181] <Replacement Treatment> A mixed solvent (IBA:EDM=1:1 by mass) of isobutyl alcohol (IBA; boiling point 108°C, manufactured by Tokyo Chemical Industry Co., Ltd.) and diethylene glycol ethyl methyl ether (EDM; boiling point 176°C, manufactured by Toho Chemical Industry Co., Ltd.) was added to the pulverized sol solution E, and after light stirring, the mixture was allowed to stand at room temperature for 6 hours to decant the dispersion medium and catalyst in the gel. The same decantation treatment was performed three times to replace the solvent in sol E.

[0182] The volume average particle diameter, which indicates the variation in particle size of the pulverized material contained in sol solution E, was confirmed using a dynamic light scattering Nanotrac particle size analyzer (UPA-EX150 model, manufactured by Microtrack Bell Co., Ltd.) and was found to be 0.50 to 0.70.

[0183] Furthermore, 0.062 g of an MEK (methyl ethyl ketone) solution containing 1.5% of a photobase generator (product name: WPBG266, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 0.036 g of an MEK solution containing 5% of bis(trimethoxysilyl)ethane were added to 0.75 g of sol solution E to obtain a coating liquid for forming a low refractive index layer.

[0184] (Preparation Example 2: Coating liquid for forming adhesive 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 of 2,2'-azobisisobutyronitrile as a polymerization initiator were charged together with 100 parts of ethyl acetate. Next, nitrogen gas was introduced with gentle stirring to replace the atmosphere with nitrogen, and then the liquid temperature in the flask was maintained at around 55°C to carry out a polymerization reaction for 8 hours, thereby preparing an acrylic polymer solution. For 100 parts of the solids content of the obtained acrylic polymer solution, 0.2 parts of an isocyanate crosslinking agent (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd., an adduct of trimethylolpropane tolylene diisocyanate), 0.3 parts of benzoyl peroxide (Niper (registered trademark) BMT, manufactured by NOF Corporation), and 0.2 parts of a silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd., γ-glycidoxypropyl methoxysilane) were blended to obtain an adhesive layer-forming coating solution containing an acrylic adhesive. Next, the adhesive layer-forming coating solution was applied to one side of a silicone-treated polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Chemical Foldings Corporation, thickness: 38.0 μm) so that the average thickness of the adhesive layer after drying was 10.0 μm, and the coating was dried at 150 ° C. for 3 minutes to form an adhesive layer.

[0185] Example 1 The laminated optical member shown in FIG. 5 was produced by laminating, in this order, an optical element 10 having an average thickness of 2.0 mm, an undercoat layer 50 having an average thickness of 5.0 nm, a low refractive index layer 20 having an average thickness of 2.0 μm, a pressure-sensitive adhesive layer 40 having an average thickness of 10.0 μm, and a light-absorbing layer 30 having an average thickness of 18.0 μm, using the following method.

[0186] The adhesive layer formed in Preparation Example 2 was transferred onto one surface of a black film (product name: CARBONFEATHER, model number: 6X4LGB, manufactured by Kimoto Co., Ltd., average thickness: 18.0 μm) serving as the light absorbing layer 30 .

[0187] Plate glass (glass type: S-BSL7, product number: 516641, manufactured by Ohara Inc., average thickness: 2.0 mm) was used as the light guide plate 10A for the optical element 10. A silane coupling agent (KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd., 3-aminopropyltrimethoxysilane) was applied to the plate glass so that the average thickness after drying would be 5.0 nm, forming an undercoat layer 50. Next, the light guide plate 10A with the undercoat layer 50 formed thereon and the low refractive index layer-forming coating liquid obtained in Preparation Example 1 were placed in a spray coater (product name: API-240 series, manufactured by Apeiros). The distance (coating distance) between the spray head (nozzle) and the surface of the light guide plate 10A on which the undercoat layer 50 was formed, facing the undercoat layer 50, was 100 mm, and the low refractive index layer-forming coating liquid was sprayed onto the undercoat layer 50 under the following coating conditions to form a coating film on the undercoat layer 50 (the surface of the undercoat layer 50 opposite the surface on which the plate glass was disposed). The spray coating was performed by repeatedly performing a first step in which the low refractive index layer-forming coating liquid was sprayed while the spray head moved in the X-axis direction of the undercoat layer 50, and a second step in which the spray head moved in the Z-axis direction of the undercoat layer 50. The coating film was then dried at a temperature of 100°C for 1 minute, forming a low refractive index layer 20 with an average thickness of 2.0 μm. Next, the pressure-sensitive adhesive layer 40 transferred to the light-absorbing layer 30 was laminated on the low-refractive-index layer 20 (the surface of the low-refractive-index layer 20 opposite to the surface on which the undercoat layer 50 was disposed) so that the surface opposite to the surface on which the light-absorbing layer 30 was disposed was in contact, and the layers were bonded using a hand roller to produce a laminated optical member 100. - Coating conditions - Atomization pressure: 100 kPa Coating amount: 7 mL / min Head speed in the first step: 300 mm / sec Head movement distance in the second step: 15 mm

[0188] The solids concentration of the low refractive index layer-forming coating liquid measured by the above method was 3.0% by mass before application, and the solids concentration of the low refractive index layer-forming coating liquid at the time of application was 5.3% by mass, resulting in a change ratio of 1.8. Furthermore, in Example 1, the viscosity of the low refractive index layer-forming coating liquid measured by the above method before application was 10.0 mPa·s, and the viscosity of the low refractive index layer-forming coating liquid after application was 522 mPa·s. The sample for measuring the refractive index of the low refractive index layer 20 was formed using the same method as in Example 1, so the solids concentration of the low refractive index layer-forming coating liquid before application, the solids concentration of the low refractive index layer-forming coating liquid at the time of application, the viscosity of the low refractive index layer-forming coating liquid before application, and the viscosity of the low refractive index layer-forming coating liquid after application were the same as in Example 1.

[0189] In the laminated optical member 100 of Example 1, the refractive index of the low refractive index layer 20 measured by the above method was 1.18, and the porosity was 60% by volume.

[0190] Comparative Example 1 An optical member of Comparative Example 1 was prepared by using a single layer of only a black film (product name: CARBONFEATHER, model number: 6X4LGB, manufactured by Kimoto Co., Ltd., average thickness: 18.0 μm) as the light absorbing layer 30 .

[0191] The layer structures of Example 1 and Comparative Example 1, as well as the refractive index and porosity of the low refractive index layer 20 measured by the above-mentioned method, are shown in Table 1 below.

[0192]

[0193] [Evaluation of External Reflection] Using the laminated optical member 100 of Example 1 and an optical member consisting only of a light absorbing layer of Comparative Example 1, external reflection was evaluated by the following method, with the exposed surface of the light absorbing layer as the outside. Figure 9 is a schematic explanatory diagram showing the method for evaluating the external reflection of the laminated optical member 100 of Example 1.

[0194] The first surface 100a on the light absorbing layer 30 side of the laminated optical member 100 of Example 1, or one surface of the light absorbing layer 30 of the optical member of Comparative Example 1, was irradiated with light using an ultraviolet-visible-near-infrared spectrophotometer (product name: UH4150, manufactured by Hitachi High-Tech Corporation) while changing the incident angle R1 from 10° to 70° in 10° increments, and the detector 150 was placed at the angle at which regular reflection occurred, and measurements were performed. The resulting reflection spectrum in the visible light region of wavelengths from 380 nm to 780 nm was converted to a luminous reflectance Y value and plotted.

[0195] The relationship between the incident angle and the luminous reflectance Y value is plotted in Figure 10. From this, it can be seen that the luminous reflectance Y value of the laminated optical member 100 of Example 1 is similar to the luminous reflectance Y value of the optical member consisting only of the light absorbing layer of Comparative Example 1, and the external reflection at the first surface 100a on the light absorbing layer 30 side maintained a low reflectance.

[0196] (Example 2) Using the following method, a regular triangular prism 10B having a side dimension of 5.0 mm, an adhesive layer 40 having an average thickness of 10.0 μm, a low refractive index layer 20 having an average thickness of 2.0 μm, a substrate 60 having an average thickness of 30.0 μm, an adhesive layer 40 having an average thickness of 10.0 μm, and a light absorbing layer 30 having an average thickness of 18.0 μm were laminated in this order to produce a laminated optical element 100 shown in FIG. 11 .

[0197] The substrate 60 (acrylic film, average thickness: 30.0 μm) and the low refractive index layer-forming coating liquid obtained in Preparation Example 1 were set in a spray coater (product name: API-240 series, manufactured by Apeiros). The distance (coating distance) between the spray head (nozzle) and one surface of the substrate 60 was 100 mm, and the low refractive index layer-forming coating liquid was spray-coated onto the substrate 60 under the coating conditions described in Example 1 to form a coating film on one surface of the substrate 60. The spray coating was performed by repeatedly performing a first step in which the low refractive index layer-forming coating liquid was sprayed while the spray head moved in the X-axis direction of the substrate 60, and a second step in which the spray head moved in the Z-axis direction of the substrate 60. The coating film was then treated and dried at a temperature of 100 ° C. for 1 minute to form a low refractive index layer 20 having an average thickness of 2.0 μm.

[0198] The adhesive layer 40 formed in Preparation Example 2 was transferred onto one surface of a black film (product name: CARBONFEATHER, model number: 6X4LGB, manufactured by Kimoto Co., Ltd., average thickness: 18.0 μm) serving as the light absorbing layer 30 .

[0199] The adhesive layer 40 transferred to the light absorbing layer 30 was laminated on the surface of the substrate 60 opposite to the surface on which the low refractive index layer 20 was arranged, so that the surface opposite to the surface on which the light absorbing layer 30 was arranged was in contact with the surface, and the two were bonded together using a hand roller.

[0200] The pressure-sensitive adhesive layer 40 formed in Preparation Example 2 was transferred to the surface of the low refractive index layer 20 opposite to the surface on which the substrate 60 was disposed. Next, a prism 10B (TS equilateral triangular prism 5.0 mm, product number: #49-430, manufactured by Edmund Optics Japan Co., Ltd., dimension of one side of the triangle: 5.0 mm) serving as the optical element 10 was laminated on the surface of the pressure-sensitive adhesive layer 40 opposite to the surface on which the low refractive index layer 20 was disposed so that one side was in contact, and the resulting laminated optical member 100 was produced by laminating the two together using a hand roller.

[0201] In Example 2, the solids concentration of the low refractive index layer-forming coating liquid measured by the above method was 3.0% by mass before application, and the solids concentration of the low refractive index layer-forming coating liquid at the time of application was 5.3% by mass, resulting in a change ratio of 1.8. Furthermore, in Example 2, the viscosity of the low refractive index layer-forming coating liquid measured by the above method before application was 10.0 mPa·s, and the viscosity of the low refractive index layer-forming coating liquid after application was 522 mPa·s. Note that the sample for measuring the refractive index of the low refractive index layer 20 was formed using the same method as in Example 2, and therefore the solids concentration of the low refractive index layer-forming coating liquid before application, the solids concentration of the low refractive index layer-forming coating liquid at the time of application, the viscosity of the low refractive index layer-forming coating liquid before application, and the viscosity of the low refractive index layer-forming coating liquid after application were the same as in Example 2.

[0202] (Example 3) The laminated optical element 100 shown in Figure 12 was produced by laminating, in this order, an equilateral triangular prism 10B with a side dimension of 5.0 mm, an undercoat layer 50 with an average thickness of 5.0 nm, a low refractive index layer 20 with an average thickness of 2.0 μm, a pressure-sensitive adhesive layer 40 with an average thickness of 10.0 μm, and a light-absorbing layer 30 with an average thickness of 18.0 μm, using the following method.

[0203] A silane coupling agent (KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd., 3-aminopropyltrimethoxysilane) was applied to one side of a prism 10B (TS equilateral triangular prism, 5.0 mm, product number: #49-430, manufactured by Edmund Optics Japan, Inc., dimension of one side of the triangle: 5 mm) serving as the optical element 10, so that the average thickness after drying would be 5.0 nm, thereby forming an undercoat layer 50. The low refractive index layer-forming coating liquid obtained in Preparation Example 1 was spray-coated onto the undercoat layer 50 (the surface opposite to the surface of the undercoat layer on which the prism was disposed) using the same method and conditions as in Example 1. The coating film was treated at a temperature of 100°C for 1 minute and dried, forming a low refractive index layer 20 with an average thickness of 2.0 μm. The pressure-sensitive adhesive layer 40 transferred to the light-absorbing layer 30 was laminated on the low-refractive index layer 20 (the surface of the low-refractive index layer 20 opposite to the surface on which the undercoat layer 50 was arranged) so that the surface opposite to the surface on which the light-absorbing layer 30 was arranged was in contact with the low-refractive index layer 20, and the layers were bonded together using a hand roller to produce the laminated optical element 100.

[0204] In Example 3, the solids concentration of the low refractive index layer-forming coating liquid measured by the above method was 3.0% by mass before application, and the solids concentration of the low refractive index layer-forming coating liquid at the time of application was 5.3% by mass, resulting in a change ratio of 1.8. Furthermore, in Example 3, the viscosity of the low refractive index layer-forming coating liquid measured by the above method before application was 10.0 mPa·s, and the viscosity of the low refractive index layer-forming coating liquid after application was 522 mPa·s. Note that the sample for measuring the refractive index of the low refractive index layer 20 was formed using the same method as in Example 3, and therefore the solids concentration of the low refractive index layer-forming coating liquid before application, the solids concentration of the low refractive index layer-forming coating liquid at the time of application, the viscosity of the low refractive index layer-forming coating liquid before application, and the viscosity of the low refractive index layer-forming coating liquid after application were the same as in Example 3.

[0205] Comparative Example 2 The optical member of Comparative Example 2 was a single layer of a prism (TS equilateral triangular prism 5.0 mm, product number: #49-430, manufactured by Edmund Optics Japan, one side dimension of the triangle: 5.0 mm) as an optical element.

[0206] (Comparative Example 3) A laminated optical element 100A shown in Figure 13 was produced by laminating, in this order, an equilateral triangular prism with a side dimension of 5.0 mm, an adhesive with an average thickness of 10 μm, and a light absorbing layer 30 with an average thickness of 18.0 μm, using the following method.

[0207] The pressure-sensitive adhesive layer 40 formed in Preparation Example 2 was transferred to one surface of a black film (trade name: CARBONFEATHER, model number: 6X4LGB, manufactured by Kimoto Co., Ltd., average thickness: 18.0 μm) serving as the light-absorbing layer 30. The pressure-sensitive adhesive layer 40 transferred to the light-absorbing layer 30 was laminated so that the surface opposite to the surface on which the light-absorbing layer 30 was disposed was in contact with one side of a prism 10B (TS equilateral triangular prism 5.0 mm, product number: #49-430, manufactured by Edmund Optics Japan Co., Ltd., dimension of one side of the triangle: 5.0 mm) serving as the optical element 10, and the laminated optical member 100A was produced by laminating the two layers together using a hand roller.

[0208] The layer structures of Example 2, Example 3, Comparative Example 2, and Comparative Example 3, as well as the refractive index and porosity of the low refractive index layer 20 measured by the above-mentioned method, are shown in Table 2 below.

[0209]

[0210] [Evaluation of Internal Reflection] Using the laminated optical members 100 of Examples 2 and 3, the laminated optical member 100A of Comparative Example 3, and an optical member consisting only of the prism 10B of Comparative Example 2, internal reflection was evaluated by the following method, with the exposed surface of the optical element 10 being the inside. Figure 14 is a schematic explanatory diagram showing the method for evaluating the external reflection of the laminated optical member 100 of Example 2.

[0211] One exposed surface 10d of the prism 10B of the laminated optical element 100 of Examples 2 and 3, one exposed surface 10d of the prism 10B of the laminated optical element 100A of Comparative Example 3, and one surface of the prism 10B of Comparative Example 2 were irradiated with a light beam L using an ultraviolet-visible-near-infrared spectrophotometer (product name: UH4150, manufactured by Hitachi High-Technologies Corporation) so that the angle R2 with respect to the reflective surface was 60°, and a detector 151 was installed at a position of 120° where regular reflection occurs, and measurements were performed under the following conditions. - Measurement conditions - Measurement start wavelength: 1,200 nm End wavelength: 300 nm Light source switching wavelength: 340 nm and 850 nm Scan speed (1): 300 nm to 850 nm, 300 nm / min, sampling interval 5 nm Scan speed (2): 850 nm to 1,200 nm, 750 nm / min, sampling interval 5 nm

[0212] The relationship between the measured wavelength and the specular reflectance is plotted in Figure 15. From this, it can be seen that the specular reflectance of the laminated optical members 100 of Examples 2 and 3 was comparable to that of the optical member consisting only of the prism 10B of Comparative Example 2, and the reflectance of internal reflection on the prism 10B side was maintained. On the other hand, the laminated optical member 100A of Comparative Example 3 did not obtain internal reflection from the prism 10B as the optical element 10.

[0213] Examples of aspects of the present disclosure include the following. <1> A laminated optical member comprising, in this order: an optical element; a low-refractive index layer having a refractive index of 1.25 or less; and a light-absorbing layer that absorbs light from a light source. <2> The laminated optical member according to <1>, wherein the optical element is a light guide plate or a prism. <3> The laminated optical member according to claim 1, wherein the light-absorbing layer has an absorption spectrum of 380 nm to 2,500 nm. <4> The laminated optical member according to <1> or <2>, wherein the low-refractive index layer has voids therein. <5> The laminated optical member according to <4>, wherein the porosity of the low-refractive index layer is 30 volume % or more relative to the total volume of the low-refractive index layer. <6> The laminated optical member according to any one of <1> to <5>, wherein the low-refractive index layer has an average thickness of 0.1 μm or more. <7> The laminated optical member according to any one of <1> to <6>, having an incident portion into which light from a light source is incident and an exit portion from which light incident on the optical element exits, wherein the low refractive index layer is disposed in a reflective portion where the light incident from the incident portion is reflected inside the optical element, and the light absorbing layer is disposed on the surface of the low refractive index layer opposite the optical element. <8> The laminated optical member according to any one of <1> to <7>, which is used in an imaging device. <9> An optical device comprising a plurality of lenses, an image sensor, and the laminated optical member according to any one of <1> to <8>. <10> An imaging device comprising, in this order, an optical element, a low refractive index layer having a refractive index of 1.25 or less, and a light absorbing layer that absorbs light from a light source.

[0214] As described above, the present disclosure has been described based on specific embodiments and examples, but these embodiments and examples are presented merely as examples, and the present disclosure is not limited to the above embodiments and examples. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, additions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as set forth in the claims.

[0215] The laminated optical member according to the embodiment of the present disclosure can be suitably used as an optical member for an optical filter, an optical member for an imaging device, an optical member for an optical sensor device, etc. Specific examples include optical members for camera modules, televisions, car navigation systems, personal digital assistants, video game consoles, portable game consoles, fingerprint authentication systems, digital music players, etc.

[0216] This international application claims priority based on Japanese Patent Application No. 2024-055971, filed on March 29, 2024, the entire contents of which are incorporated herein by reference.

[0217] 10 Optical element 10A Light guide plate 10B Prism 10a End face 10b Emission surface 10c Light extraction pattern 10d One exposed surface of prism 10B 20 Low refractive index layer 20-1 First inner surface 20-2 Second inner surface 20-3 Third inner surface 30 Light absorbing layer 40 Pressure sensitive adhesive layer 50 Undercoat layer 60 Substrate 70 Incident section 80 Emission section 90 Multiple lenses 90a First lens 90b Second lens 90c Third lens 90d Fourth lens 95 Image sensor 100 Laminated optical member 100a First surface 100b Second surface 150 Detector 151 Detector 200 Optical device L Light

Claims

1. A laminated optical member comprising, in this order: an optical element; a low refractive index layer having a refractive index of 1.25 or less; and a light absorbing layer that absorbs light from a light source.

2. The laminated optical member according to claim 1, wherein the optical element is a light guide plate or a prism.

3. The laminated optical member according to claim 1 or 2, wherein the absorption spectrum of the light-absorbing layer is from 380 nm to 2,500 nm.

4. A laminated optical member according to any one of claims 1 to 3, wherein the low refractive index layer has voids therein.

5. The laminated optical member according to claim 4, wherein the porosity of the low refractive index layer is 30% by volume or more relative to the total volume of the low refractive index layer.

6. The laminated optical member according to any one of claims 1 to 5, wherein the low refractive index layer has an average thickness of 0.1 µm or more.

7. A laminated optical element according to any one of claims 1 to 6, comprising an incident portion where light from a light source is incident and an exit portion where light incident on the optical element exits, the low refractive index layer is disposed in a reflecting portion where the light incident from the incident portion is reflected inside the optical element, and the light absorption layer is disposed on the surface of the low refractive index layer opposite to the optical element.

8. The laminated optical member according to claim 1, which is used in an imaging device.

9. An optical device comprising a plurality of lenses, an image sensor, and the laminated optical member according to any one of claims 1 to 8.

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