Antireflection member

Abstract

An antireflection member comprising: a resin base; and a particle layer that is disposed on the surface of the resin base and that includes mesoporous silica nanoparticles, wherein a portion of the nanoparticles is directly fixed to the surface of the resin base, at least a portion of the nanoparticles directly fixed to the surface of the resin base is embedded in the surface of the resin base, at least two layers of the nanoparticles are disposed to form the particle layer, the thickness of the particle layer is 2-10 times the average particle size of the nanoparticles, and the proportion of the area occupied by the particle layer including the nanoparticles with respect to the total surface area of the resin base is at least 95%.

Description

Anti-reflection member

[0001] The present invention relates to an anti-reflection member.

[0002] Conventionally, various types of anti-reflection films and anti-reflection materials have been studied to prevent light reflection on the surface of optical components and the like. For example, Japanese Patent Application Laid-Open No. 2016-95498 (Patent Document 1) discloses an anti-reflection member including a resin substrate and a particle layer composed of mesoporous nanosilica particles directly immobilized on the surface of the resin substrate, at least a part of the nanoparticles being embedded in the surface of the resin substrate, and the nanoparticles being arranged in a single layer to form the particle layer. This anti-reflection member has excellent anti-reflection performance, and Patent Document 1 describes that by forming a single-layer particle layer composed of the mesoporous nanosilica particles on a resin substrate, the light reflectance in the wavelength range of 400 to 800 nm is reduced and the light transmittance is increased.

[0003] Japanese Patent Application Laid-Open No. 2016-95498

[0004] However, in the anti-reflection member described in Patent Document 1, the anti-reflection performance in the near-infrared wavelength range (800 to 2500 nm) is not always sufficient, and there is a demand for an anti-reflection member having excellent anti-reflection performance (for example, high light transmittance) in the near-infrared wavelength range.

[0005] The present invention has been made in view of the problems of the above prior art, and an object thereof is to provide an anti-reflection member having a high light transmittance in the near-infrared wavelength range (800 to 2500 nm).

[0006] As a result of diligent research to achieve the above objective, the present inventors have found that an anti-reflective member comprising a resin substrate and a particle layer made of mesoporous nanosilica particles arranged on the surface of the resin substrate, wherein some of the nanoparticles are directly immobilized on the surface of the resin substrate, at least some of the nanoparticles directly immobilized on the surface of the resin substrate are embedded in the surface of the resin substrate, the nanoparticles are arranged in two or more layers to form the particle layer, the thickness of the particle layer is 2 to 10 times the average particle diameter of the nanoparticles, and the ratio of the area occupied by the particle layer made of nanoparticles to the total surface area of ​​the resin substrate is 95% or more has high light transmittance in the near-infrared wavelength range (800 to 2500 nm), and have completed the present invention.

[0007] In other words, the present invention provides the following embodiments: [1] An anti-reflective member comprising a resin substrate and a particle layer made of mesoporous silica nanoparticles disposed on the surface of the resin substrate, wherein some of the nanoparticles are directly immobilized on the surface of the resin substrate, and at least some of the nanoparticles directly immobilized on the surface of the resin substrate are embedded in the surface of the resin substrate, the nanoparticles are arranged in two or more layers to form the particle layer, the thickness of the particle layer is 2 to 10 times the average particle diameter of the nanoparticles, and the ratio of the area occupied by the particle layer made of nanoparticles to the total surface area of ​​the resin substrate is 95% or more. [2] The anti-reflective member according to [1], wherein the average particle diameter of the nanoparticles is 50 to 300 nm. [3] The anti-reflective member according to [1] or [2], wherein the mesoporous silica nanoparticles are surface hydrophobized mesoporous silica nanoparticles. [4] The anti-reflective member according to any one of [1] to [3], wherein the mesoporous silica nanoparticles are nanoparticles with a porosity of 20 to 70%. [5] The anti-reflective member according to any one of [1] to [4], wherein the resin substrate is made of a transparent resin.

[0008] Although the reason why the anti-reflective member of the present invention has high light transmittance in the near-infrared wavelength range (800 to 2500 nm) is not entirely clear, the inventors speculate as follows.

[0009] In other words, in the anti-reflective member of the present invention, it is presumed that the refractive index of the nanoparticles themselves is reduced by the mesoporous structure of the mesoporous silica nanoparticles, and that the rapid change in refractive index is mitigated by the partial penetration of the resin of the resin substrate into the nanoparticles, thereby increasing the light transmittance in the near-infrared wavelength range.

[0010] Furthermore, in the anti-reflective member of the present invention, since the mesoporous silica nanoparticles are arranged in two or more layers on the surface of the resin substrate to form a particle layer, it is presumed that the light transmittance in the near-infrared wavelength range is increased because the mesoporous silica nanoparticles are appropriately exposed on the surface of the anti-reflective member, forming an uneven structure with protrusions of appropriate height.

[0011] According to the present invention, it is possible to obtain an anti-reflective member having high light transmittance in the near-infrared wavelength range (800 to 2500 nm).

[0012] This is a scanning electron microscope image showing the mesoporous silica nanoparticles obtained in Preparation Example 1. This is a graph showing the nitrogen adsorption isotherm of the mesoporous silica nanoparticles obtained in Preparation Example 1. This is a scanning electron microscope image showing the silica nanoparticles after surface hydrophobic treatment obtained in Preparation Example 2. This is a scanning electron microscope image showing a cross-section of the anti-reflective member obtained in Example 1. This is an atomic force microscope image showing the surface of the anti-reflective member obtained in Example 1. This is a graph showing the wavelength dependence of the light transmittance of the anti-reflective member and the untreated acrylic resin substrate obtained in Example 1. This is a scanning electron microscope image showing a cross-section of the anti-reflective member obtained in Example 2. This is an atomic force microscope image showing the surface of the anti-reflective member obtained in Example 2. This is a graph showing the wavelength dependence of the light transmittance of the anti-reflective member and the untreated acrylic resin substrate obtained in Example 2. This is a scanning electron microscope image showing a cross-section of the anti-reflective member obtained in Example 3. This is an atomic force microscope image showing the surface of the anti-reflective member obtained in Example 3. This is a graph showing the wavelength dependence of the light transmittance of the anti-reflective member and the untreated polyetherimide resin substrate obtained in Example 3. This is a photograph showing the appearance of the anti-reflective member obtained in Example 4. This is a scanning electron microscope image showing a cross-section of the anti-reflective member obtained in Example 4. This is an atomic force microscope image showing the surface of the anti-reflective member obtained in Example 4. This is a scanning electron microscope image showing a cross-section of the anti-reflective member obtained in Example 5. This is an atomic force microscope image showing the surface of the anti-reflective member obtained in Example 5. This is a graph showing the wavelength dependence of the light transmittance of the anti-reflective member and the untreated acrylic resin substrate obtained in Example 5. This is a scanning electron microscope image showing a cross-section of the anti-reflective member obtained in Example 6. This is an atomic force microscope image showing the surface of the anti-reflective member obtained in Example 6. This is a graph showing the wavelength dependence of the light transmittance of the anti-reflective member and the untreated acrylic resin substrate obtained in Example 6. This is a scanning electron microscope image showing a cross-section of the anti-reflective member obtained in Comparative Example 1. This is an atomic force microscope image showing the surface of the anti-reflective member obtained in Comparative Example 1. This is a graph showing the wavelength dependence of the light transmittance of the anti-reflective member and the untreated acrylic resin substrate obtained in Comparative Example 1. This is a scanning electron microscope image showing a cross-section of the anti-reflective material obtained in Comparative Example 2.This is an atomic force microscope image showing the surface of the anti-reflective material obtained in Comparative Example 2. This is a graph showing the wavelength dependence of the light transmittance of the anti-reflective material obtained in Comparative Example 2 and the untreated acrylic resin substrate. This is a scanning electron microscope image showing the cross-section of the anti-reflective material obtained in Comparative Example 3. This is an atomic force microscope image showing the surface of the anti-reflective material obtained in Comparative Example 3. This is a graph showing the wavelength dependence of the light transmittance of the anti-reflective material obtained in Comparative Example 3 and the untreated acrylic resin substrate.

[0013] The present invention will be described in detail below with reference to its preferred embodiments.

[0014] [Anti-reflective member] First, the anti-reflective member of the present invention will be described. The anti-reflective member of the present invention comprises a resin substrate and a particle layer made of mesoporous nanosilica particles arranged on the surface of the resin substrate. In the anti-reflective member of the present invention, some of the nanoparticles are directly fixed to the surface of the resin substrate, and at least a portion of the nanoparticles directly fixed to the surface of the resin substrate are embedded in the surface of the resin substrate. Furthermore, in the anti-reflective member of the present invention, the nanoparticles are arranged in two or more layers to form the particle layer, the thickness of the particle layer is 2 to 10 times the average particle diameter of the nanoparticles, and the ratio of the area occupied by the particle layer made of nanoparticles to the total surface area of ​​the resin substrate is 95% or more.

[0015] (Resin Substrate) The resin substrate according to the present invention is a resin that serves as the base material for the anti-reflective member. Any resin substrate that can be used for the anti-reflective member is acceptable and is not particularly limited; known resins can be used as appropriate. However, from the viewpoint of improving visibility, transparent resins are preferred. Specifically, such resins include thermoplastic resins such as acrylic resin, polycarbonate resin, polycycloolefin resin, polystyrene resin, polyvinyl chloride resin, polyimide resin, and polyetherimide resin. Furthermore, from the viewpoint of reducing the difference in refractive index with that of the mesoporous silica nanoparticles described later, acrylic resin and polyetherimide resin are preferred.

[0016] Furthermore, the resin substrate according to the present invention may be in any form that is suitable for use as an anti-reflective member, and is not particularly limited. For example, it can be in the form of a sheet, film, plate, dome, sphere, cube, etc. The thickness and size of the resin substrate according to the present invention are not particularly limited and can be appropriately selected according to the application of the anti-reflective member (desired product or part, etc.).

[0017] (Particle layer) The particle layer according to the present invention is a particle layer made of mesoporous silica nanoparticles and is arranged on the surface of the resin substrate. Furthermore, in the particle layer, some of the nanoparticles are directly fixed to the surface of the resin substrate, and at least a portion of the nanoparticles directly fixed to the surface of the resin substrate are embedded in the surface of the resin substrate. Moreover, the particle layer is formed by arranging the nanoparticles in two or more layers, and the thickness of the particle layer is 2 to 10 times the average particle diameter of the nanoparticles.

[0018] Here, in the particle layer of the present invention, "some of the nanoparticles are directly fixed to the surface of the resin substrate" means that some of the nanoparticles constituting the particle layer are directly fixed to the resin substrate without the interposition of other substances. In other words, it means that some of the nanoparticles constituting the particle layer and the resin substrate are directly bonded together. Because the nanoparticles are directly fixed to the surface of the resin substrate, a strong adhesive force is provided between the nanoparticles and the resin substrate, and a particle layer is formed in which the nanoparticles do not detach even by ultrasonic cleaning or by tape peeling tests using adhesive tape.

[0019] Furthermore, in the particle layer of the present invention, "at least a portion of the nanoparticles directly immobilized on the surface of the resin substrate are embedded in the surface of the resin substrate" means that a portion or all of the nanoparticles directly immobilized on the surface of the resin substrate are embedded in or mixed into the surface of the resin substrate.

[0020] Furthermore, in the particle layer of the present invention, "the nanoparticles are arranged in two or more layers to form the particle layer" means that the nanoparticles are further overlapped on a single layer of nanoparticles that are directly fixed to the surface of the resin substrate to form two or more particle layers.

[0021] Furthermore, in the particle layer of the present invention, the thickness of the particle layer is preferably 2 to 5 times the average particle diameter of the nanoparticles, and more preferably 2 to 10 times. If the thickness of the particle layer is less than the lower limit, excellent anti-reflective performance tends not to be obtained in the near-infrared wavelength range, and if it exceeds the upper limit, the anti-reflective performance tends to decrease on the lower wavelength side of the near-infrared wavelength range.

[0022] The mesoporous silica nanoparticles (hereinafter sometimes simply referred to as "nanoparticles") are not particularly limited as long as they have a large number of mesopores. For example, nanoparticles having a large number of mesopores with a diameter of 2 to 50 nm can be used. Such nanoparticles, by having a structure with a large number of mesopores (mesoporous structure), can sufficiently secure the porosity of the nanoparticles and reduce the refractive index, thereby forming an anti-reflective member with excellent anti-reflective layer performance (e.g., high light transmittance). Furthermore, since some of the nanoparticles are directly fixed to the surface of the resin substrate, and at least some of the nanoparticles directly fixed to the surface of the resin substrate are embedded in the surface of the resin substrate, the resin and the nanoparticles are firmly fixed, and an anti-reflective member with excellent wear resistance can be formed. In addition, sufficient mechanical strength of the anti-reflective member is ensured. Furthermore, the mesoporous silica nanoparticles contain silica (light absorption coefficient: 0.1 cm²). －１ It has a framework with a refractive index of less than 1.45, and due to its low refractive index, it provides excellent anti-reflective properties.

[0023] In such nanoparticles, the average particle diameter is preferably 50 to 300 nm. If the average particle diameter of the nanoparticles falls below the lower limit, the uneven structure derived from the shape of the nanoparticles exposed on the surface of the particle layer becomes smaller, and excellent anti-reflective performance (e.g., high light transmittance) tends not to be obtained. If it exceeds the upper limit, the thickness of each particle layer becomes thicker, making it difficult to adjust the overall thickness of two or more particle layers. Furthermore, from the viewpoint of further improving anti-reflective performance (e.g., light transmittance), the average particle diameter of such nanoparticles is more preferably 100 to 250 nm, and particularly preferably 120 to 220 nm. The average particle diameter of nanoparticles can be determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), or electron beam microanalyzer (EPMA). It can also be measured by dynamic light scattering. For example, when using scanning electron microscopy (SEM) observation, the average particle diameter of the nanoparticles is determined by randomly selecting 50 or more nanoparticles in the SEM observation and measuring their diameters.

[0024] Furthermore, in such nanoparticles, the porosity is preferably 20 to 70%, and more preferably 30 to 60%. If the porosity of the nanoparticles falls below the lower limit, the refractive index of the nanoparticles themselves increases, and excellent anti-reflective performance (e.g., high light transmittance) tends not to be obtained. On the other hand, if it exceeds the upper limit, the nanoparticles themselves become brittle, and the mechanical strength of the anti-reflective member tends to decrease. The porosity of the nanoparticles can be determined from nitrogen adsorption isotherms.

[0025] Furthermore, while there are no particular restrictions on the shape of the mesopores in such nanoparticles, radial pores are preferred. This shape allows for more robust fixation of the nanoparticles to the surface of the resin substrate.

[0026] (Anti-reflective member) The anti-reflective member of the present invention comprises the resin substrate and a particle layer made of mesoporous nanosilica particles arranged on the surface of the resin substrate.

[0027] In such an anti-reflective member, it is preferable that the area occupied by the particle layer made of nanoparticles is 95% or more, and 98% or more, relative to the total surface area of ​​the resin substrate. If the area occupied by the particle layer falls below the lower limit, excellent anti-reflective performance (e.g., high light transmittance) in the near-infrared wavelength range tends not to be obtained.

[0028] The anti-reflective member of the present invention, with the above configuration, has excellent anti-reflective performance (e.g., high light transmittance) in the near-infrared wavelength range. That is, in the anti-reflective member of the present invention, because the surface area of ​​the nanoparticles is large, the nanoparticles can be directly immobilized on the surface of the resin substrate, and furthermore, two or more particle layers can be formed by stacking the nanoparticles on top of them. As a result, an anti-reflective member is obtained that has a low refractive index particle layer with an uneven structure having protrusions of appropriate height on its surface, and has excellent anti-reflective performance (e.g., high light transmittance) in the near-infrared wavelength range. Furthermore, such an anti-reflective member has excellent mechanical strength because some of the nanoparticles are directly immobilized on the surface of the resin substrate, and at least some of the nanoparticles directly immobilized on the surface of the resin substrate are embedded in the surface of the resin substrate. Therefore, it can be easily applied to curved surfaces and resin substrates with complex shapes, and the range of applications can be expanded.

[0029] Furthermore, in the anti-reflective member of the present invention, individual, independent nanoparticles are immobilized on the surface of a resin substrate, and furthermore, nanoparticles are firmly bonded and arranged on top of them to form two or more particle layers. Therefore, deterioration and damage are less likely to occur even with deformation of the resin substrate (thermal expansion, mechanical deformation, etc.), and the member has excellent durability. Consequently, it can be applied to curved or complexly shaped resin parts, flexible substrates, and the like. Moreover, by optimizing the material of the resin substrate, the shape and embedding structure of the nanoparticles, etc., the anti-reflective member of the present invention can also be made to have excellent bending durability.

[0030] (Method for manufacturing an anti-reflective member) The anti-reflective member of the present invention can be manufactured by a method that includes, for example, a step of embedding at least a portion of mesoporous silica nanoparticles arranged on the surface of a resin substrate in a polymer fluid state on the surface of the resin substrate (particle embedding step), and a step of curing the surface of the resin substrate in a polymer fluid state to directly immobilize the nanoparticles on the surface of the resin substrate, and bonding the nanoparticles to the nanoparticles directly immobilized on the surface of the resin substrate to obtain an anti-reflective member having a particle layer in which the nanoparticles are arranged in two or more layers (immobilization step (anti-reflective member manufacturing step)).

[0031] (Particle embedding process) In the method for manufacturing the anti-reflective member, first, at least a portion of the mesoporous silica nanoparticles arranged on the surface of the resin substrate are embedded on the surface of the resin substrate, which is in a polymer flow state (particle embedding process).

[0032] In such a particle embedding process, the resin substrate is a resin that serves as the base material for the anti-reflective member, and there are no particular restrictions as long as it can form a polymer flow state on the surface of the resin substrate. Specifically, the resin substrate described in the anti-reflective member of the present invention can be used.

[0033] Furthermore, in such a particle embedding process, there are no particular restrictions on the mesoporous silica nanoparticles, and those described in the anti-reflective member of the present invention can be used.

[0034] The method for producing such mesoporous silica nanoparticles is not particularly limited and can be produced by known methods. For example, mesoporous nanoparticles can be prepared by hydrolyzing and condensing a metal alkoxide having silicon as a metal atom, such as tetraalkoxysilane, trialkoxysilane, or dialkoxysilane, in the presence of a surfactant. Alternatively, mesoporous silica nanoparticles can be prepared by hydrolyzing and condensing the aforementioned metal alkoxide in the presence of a surfactant. Furthermore, commercially available mesoporous silica nanoparticles may also be used.

[0035] Examples of such metal alkoxides include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, and dimethoxydiethoxysilane; trimethoxysilanol, triethoxysilanol, trimethoxymethylsilane, trimethoxyvinylsilane, triethoxyvinylsilane, 3-glycidoxypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, and phenyltrimeth Examples include trialkoxysilanes such as xysilane, phenyltriethoxysilane, γ-(methacryloxypropyl)trimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; and dialkoxysilanes such as dimethoxydimethylsilane, diethoxydimethylsilane, diethoxy-3-glycidoxypropylmethylsilane, dimethoxydiphenylsilane, and dimethoxymethylphenylsilane. Among these, tetraalkoxysilane, trialkoxysilane, and dialkoxysilane are preferred, with tetraalkoxysilane and trialkoxysilane being more preferred. Furthermore, these metal alkoxides may be used individually or in combination of two or more.

[0036] Examples of the surfactant include alkylammonium halides having a long-chain alkyl group with 8 to 26 carbon atoms. Among these, alkyltrimethylammonium halides having a long-chain alkyl group with 9 to 26 carbon atoms, such as tetradecyltrimethylammonium halide, hexadecyltrimethylammonium halide, and octadecyltrimethylammonium halide, are preferred. Tetradecyltrimethylammonium halide and hexadecyltrimethylammonium halide are more preferred, and tetradecyltrimethylammonium chloride and hexadecyltrimethylammonium chloride are particularly preferred.

[0037] In the particle embedding process, "the surface of the resin substrate in a polymer flow state" means that at least the surface of the resin substrate is in a state in which the polymer flows, such as a plastic state, a molten state, or a dissolved state, in which the nanoparticles can be embedded or mixed.

[0038] Further, the viscosity of the resin base material in such a high molecular fluid state is preferably 0.3 to 800 Pa·s, more preferably 0.5 to 500 Pa·s, and particularly preferably 1 to 200 Pa·s. When the viscosity of such a resin base material is less than the lower limit, the nanoparticles on the surface tend to be buried inside the resin substrate. On the other hand, when it exceeds the upper limit, the nanoparticles are not surface-fixed and tend to easily fall off.

[0039] Further, in the particle embedding step, the method of disposing the mesoporous silica nanoparticles on the surface of the resin base material is not particularly limited. For example, there is a method of applying a particle layer raw material containing mesoporous silica nanoparticles to the surface of the resin base material (particle layer raw material coating method).

[0040] In such a particle layer raw material coating method, first, the mesoporous silica nanoparticles and a dispersion medium are mixed to prepare a particle layer raw material dispersion liquid. Examples of the dispersion medium include alcohols such as methanol, ethanol, n-propanol, and isopropanol, and water-soluble organic solvents such as acetone, tetrahydrofuran, and N,N-dimethylformamide. From the viewpoint of obtaining a particle layer raw material dispersion liquid in which the nanoparticles are uniformly dispersed, the concentration of the nanoparticles in the particle layer raw material dispersion liquid is preferably 0.1 to 10% by mass.

[0041] Next, a particle layer raw material dispersion liquid containing nanoparticles is applied to the surface of the resin base material. The method of applying the particle layer raw material dispersion liquid is not particularly limited, and known methods such as direct application with a brush or a pen, dip coating, spin coating, and spray coating can be adopted. When applying to a resin base material having a curved surface, from the viewpoint of applying the nanoparticles evenly, it is preferable to apply with a brush or a spray.

[0042] In such a particle embedding step, as a method for forming a resin base material in a high molecular fluid state, for example, there is a method of plasticizing the surface of the resin base material by subjecting the surface of the resin base material to solvent vapor treatment to make it in a high molecular fluid state. By such a method, at least the surface of the resin base material can be easily formed into a high molecular fluid state of the resin.

[0043] The solvent vapor treatment is not particularly limited as long as it is a method that can plasticize the surface of the resin substrate and put it into a polymer flow state by vapor treatment using a solvent. Specifically, examples include a method in which the resin substrate is plasticized (softened) and put into a polymer flow state using the vapor of an organic solvent such as acetone, chloroform, dichloromethane, tetrahydrofuran, ethyl acetate, toluene, dimethylformamide, dimethylacetamide, or N-methylpyrrolidone. As for the solvent used in such solvent vapor treatment, it is preferable to use an organic solvent that is a low molecular weight compound with high affinity for polymers, such as acetone, chloroform, dichloromethane, tetrahydrofuran, or ethyl acetate, from the viewpoint of having a relatively low boiling point and high solubility of resins.

[0044] In the solvent vapor treatment described above, a particle layer in which mesoporous silica nanoparticles are arranged in two or more layers can be formed by appropriately adjusting the vapor concentration of the organic solvent and the exposure time to the organic solvent. The vapor concentration of the organic solvent is preferably 50% or more of the saturation concentration of the organic solvent, more preferably 75% or more, even more preferably 90% or more, and particularly preferably the saturation concentration of the organic solvent. If the vapor concentration of the organic solvent falls below the lower limit, it tends to become difficult to form a particle layer in which mesoporous silica nanoparticles are arranged in two or more layers. The exposure time to the organic solvent is preferably 5 to 600 minutes, more preferably 10 to 300 minutes, even more preferably 10 to 240 minutes, and particularly preferably 10 to 180 minutes. If the exposure time to the organic solvent falls below the lower limit, the resin substrate cannot be sufficiently plasticized (softened) to create a polymer flow state, making it difficult to embed the nanoparticles on the surface of the resin substrate. If the exposure time exceeds the upper limit, deterioration and deformation of the resin substrate are induced, and it becomes difficult to ensure the reproducibility of the embedding process.

[0045] In addition, as the mesoporous silica nanoparticles used in the particle embedding step, mesoporous silica nanoparticles whose surface is hydrophobized (a hydrophobic group is introduced onto the surface) (hereinafter also referred to as "surface-hydrophobized nanoparticles") are preferable. By using such surface-hydrophobized nanoparticles, the affinity between the resin base material and the surface-hydrophobized nanoparticles increases and the adhesion becomes stronger, and the abrasion resistance and antireflection performance of the obtained antireflection member tend to be improved. In addition, since aggregation of the nanoparticles in the solvent is suppressed, long-term storage of the dispersion liquid becomes possible.

[0046] Specific examples of such hydrophobization treatment include a method of introducing a hydrocarbon group such as an alkyl group (hydrophobic group) onto the surface of the nanoparticles by adding an organometallic compound such as chlorotrialkylsilane having a hydrocarbon group (hydrophobic group) such as an alkyl group (for example, chlorotrimethylsilane, chlorotriethylsilane), ethoxytrialkylsilane, etc. In addition, specific examples of such hydrophobization treatment include a method of introducing a hydrocarbon group such as an alkyl group (hydrophobic group) onto the surface of the nanoparticles by adding an organometallic compound having a hydrocarbon group such as an alkyl group (hydrophobic group) and an acid. Examples of the organometallic compound include organosilicon compounds such as hexaalkyldisiloxane (for example, hexamethyldisiloxane, hexaethyldisiloxane), hexaalkyldisilazane (for example, hexamethyldisilazane), trialkylmonoalkoxysilane (for example, trimethylmethoxysilane, trimethylethoxysilane); organotitanium compounds such as tetrakis(trimethylsiloxy)titanium; and organoaluminum compounds such as aluminum alkyl acetoacetate diisopropoxide. Among these, it is preferable to use an organometallic compound containing the same kind of metal atom as the metal alkoxide used. Further, examples of the acid include hydrochloric acid, acetic acid, nitric acid, trifluoroacetic acid, p-toluenesulfonic acid, sulfuric acid, etc.

[0047] Furthermore, one such hydrophobic treatment involves introducing hydrophobic groups derived from a coupling agent into the surface of nanoparticles by contacting the nanoparticles with a coupling agent having hydrophobic groups. For example, by immersing nanoparticles in a solution containing a coupling agent having hydrophobic groups or by heating while mixing a solution containing nanoparticles, hydrophobic groups (e.g., hydrocarbon groups such as alkyl groups) derived from the coupling agent are introduced into the surface of the nanoparticles. There are no particular restrictions on the coupling agent as long as it is capable of introducing hydrophobic groups, but examples of silane coupling agents include trialkylchlorosilanes (e.g., trimethylchlorosilane, triethylchlorosilane, tripropylchlorosilane), trialkylmonalkoxysilanes (e.g., trimethylmethoxysilane, trimethylethoxysilane), trifluoroalkyldialkylchlorosilanes (e.g., trifluoropropyldimethylchlorosilane), and (heptadecafluoro-1,1,2,2-tetrahydrodecyl)dimethylchlorosilane.

[0048] (Immobilization process (Anti-reflective member manufacturing process)) Next, in the method for manufacturing the anti-reflective member, the surface of the resin substrate in the polymer fluid state is cured to directly immobilize the nanoparticles on the surface of the resin substrate, thereby obtaining the anti-reflective member of the present invention (immobilization process). In this immobilization process, the surface of the resin substrate in the polymer fluid state is cured by removing the solvent used in the particle embedding process.

[0049] This method makes it possible to easily manufacture anti-reflective members having excellent anti-reflective layer performance (e.g., high light transmittance) in the near-infrared wavelength range. Specifically, in the manufacturing method of the anti-reflective member, because the surface area of ​​the nanoparticles is large, the resin and the nanoparticles are firmly bonded together as the polymer fluid state on the surface of the resin substrate is achieved. Furthermore, by curing the surface of the resin substrate, the nanoparticles can be directly fixed to the surface of the resin substrate, and furthermore, two or more particle layers can be formed by stacking the nanoparticles on top of them. As a result, an anti-reflective member having excellent anti-reflective performance (e.g., high light transmittance) in the near-infrared wavelength range can be obtained, which has a low refractive index particle layer with an uneven structure having protrusions of appropriate height on its surface. Moreover, by manufacturing in this way, some of the nanoparticles are directly fixed to the surface of the resin substrate, and at least some of the nanoparticles directly fixed to the surface of the resin substrate are embedded in the surface of the resin substrate, so the resulting anti-reflective member can also exhibit excellent mechanical strength. Therefore, anti-reflective members with curved surfaces and complex shapes can be easily manufactured, and the range of applications can be expanded.

[0050] Furthermore, in the method for manufacturing the anti-reflective member, individual, independent nanoparticles are directly immobilized on the surface of a resin substrate, and then individual, independent nanoparticles are stacked on top of them to form two or more particle layers. As a result, the resulting particle layers are resistant to thermal expansion and deformation of the resin substrate and have excellent durability. It is also possible to obtain an anti-reflective member with excellent bending durability by optimizing the material of the resin substrate, the shape of the nanoparticles, and the method of forming the embedded structure.

[0051] (Removal Step) In the method for manufacturing such an anti-reflective member, it is preferable to further include a step of removing mesoporous silica nanoparticles that were not immobilized on the surface of the resin substrate and mesoporous silica nanoparticles that are not bound to adjacent mesoporous silica nanoparticles. There are no particular limitations on the method for removing such mesoporous silica nanoparticles that were not immobilized on the surface of the resin substrate and mesoporous silica nanoparticles that are not bound to adjacent mesoporous silica nanoparticles, and examples include ultrasonic cleaning with a solvent such as ethanol or water. Specifically, the anti-reflective member obtained in the immobilization step is immersed in a solvent placed in an ultrasonic cleaner, and cleaning is performed by applying ultrasound in that state. As the organic solvent, alcohols such as ethanol, methanol, and isopropanol, or acetone, trichloroethylene, etc., can be used. Such ultrasonic cleaning makes it possible to effectively remove excess nanoparticles such as nanoparticles that were not immobilized on the surface of the resin substrate and nanoparticles that are not bound to adjacent nanoparticles.

[0052] The present invention will be described more specifically below based on examples and comparative examples, but the present invention is not limited to the following examples. Morphological observation, mesopore structure evaluation, and optical property evaluation of the anti-reflective members were performed according to the following methods.

[0053] <Morphological Observation> Scanning electron microscope (SEM) observation of silica nanoparticles was performed using the "SU3500" scanning electron microscope manufactured by Hitachi High-Technologies Corporation. In addition, atomic force microscope (AFM) observation of the surface shape of the substrate (anti-reflective material) on which silica nanoparticles were immobilized was performed using the "NanoNavi E-sweep" scanning probe microscope manufactured by Hitachi High-Tech Science Corporation. In atomic force microscope images (AFM images), if no exposure of the substrate surface was observed, the ratio of the area occupied by the particle layer consisting of silica nanoparticles to the total surface area of ​​the substrate was assumed to be approximately 100%. On the other hand, when exposure of the substrate surface was observed, the silica nanoparticles and the substrate surface were distinguished by image binarization processing using a threshold of height H2 (H2 < H1) where the frequency was half of the maximum frequency at height H1, the height showing the maximum frequency in the frequency distribution with respect to height of the AFM image. The area ratio of silica nanoparticles in the AFM image was calculated and this was taken as the ratio of the area occupied by the particle layer consisting of silica nanoparticles to the total surface area of ​​the substrate. <Mesoporous structure evaluation> The nitrogen adsorption isotherm of mesoporous silica nanoparticles was measured using the gas adsorption amount measuring device "Autosorb-1" manufactured by Quantachrome Instruments, and the specific surface area was calculated using the BET (Brunauer-Emmett-Teller) method, the pore diameter using the density functional theory, and the pore volume using the t-plot method. <Optical properties evaluation> Light transmittance was measured using the spectrophotometer "V-670" manufactured by JASCO Corporation.

[0054] (Preparation Example 1) A 100 ml round-bottom flask was filled with 60 ml of 10% by mass aqueous solution of hexamethyltrimethylammonium chloride and 0.18 g of triethanolamine, and stirred at 80°C for 1 hour. Next, a mixture of tetraethoxysilane (4 ml) and methylcyclohexane (16 ml), prepared separately, was slowly added to the resulting mixed solution to form a two-layer separation consisting of an organic layer and an aqueous layer. The mixture was then heated at 80°C for 10 hours with slow stirring at 150-200 rpm to generate nanoparticles. The aqueous layer containing the generated nanoparticles was then separated and transferred to a 300 ml round-bottom flask. A mixture of hexamethyldisiloxane (30 g), ethanol (30 g), and 5 M hydrochloric acid (60 g), prepared separately, was added to the mixture and heated at 72°C for 2 hours with vigorous stirring to perform surface hydrophobic treatment. After cooling to room temperature, the mesoporous silica nanoparticles were recovered by centrifugation (4000 rpm, 1 hour). Next, the mixture was washed with ethanol solvent by centrifugation (4000 rpm, 1 hour x 3) to remove the solvent, and then ethanol solvent was added again to obtain an ethanol dispersion (18 g) containing 5% by mass of mesoporous silica nanoparticles (surface hydrophobized mesoporous silica nanoparticles).

[0055] The obtained mesoporous silica nanoparticles were observed using a scanning electron microscope (SEM). Figure 1 shows a scanning electron microscope image of the obtained mesoporous silica nanoparticles. In this SEM observation, 50 nanoparticles were randomly selected and their diameters were measured, confirming that the average particle size of the nanoparticles was approximately 150 nm. Nitrogen adsorption isotherms were also measured. Figure 2 shows the nitrogen adsorption isotherms of the obtained mesoporous silica nanoparticles. From the nitrogen adsorption isotherm measurement results, the BET specific surface area was found to be 484 m². ２ / g, mesopore diameter 4.7 nm, pore volume derived from mesopores 0.37 cm³ ３ The density of the silica skeleton was calculated to be approximately 2 g / cm³. ３ In that case, the void ratio was calculated to be 42%.

[0056] (Preparation Example 2) Spherical silica nanoparticles (SeaHostar KE-P15, manufactured by Nippon Shokubai Co., Ltd., average particle size: 150 nm) (300 mg) and ethoxytrimethylsilane (200 μl) were sealed in a pressure-resistant vial and heated at 120°C for 3 hours. After heating, the spherical silica nanoparticles were removed and vacuum-dried at 100°C for 6 hours to obtain silica nanoparticles whose surfaces were hydrophobized with trimethylsilyl groups. These hydrophobized silica nanoparticles were observed using a scanning electron microscope (SEM). Figure 3 shows a scanning electron microscope image of the hydrophobized silica nanoparticles. In this SEM observation, 50 nanoparticles were randomly extracted and their diameters were measured. It was confirmed that the hydrophobized silica nanoparticles were spherical with an average particle size of approximately 150 nm.

[0057] Ethanol solvent (5.7 g) was added to the obtained surface hydrophobic spherical silica nanoparticles, and sonication was performed for 30 minutes to obtain an ethanol dispersion containing 5% by mass of surface hydrophobic spherical silica nanoparticles.

[0058] (Example 1) First, an ethanol dispersion (22 ml) containing 5% by mass of surface hydrophobic mesoporous silica nanoparticles (average particle size: 150 nm) obtained in Preparation Example 1 was applied to a flat acrylic resin substrate (Mitsubishi Chemical Corporation's "Acrypet", thickness: 2 mm) using a flat brush (material: sheep's wool, bristle length: 12 mm, bristle width: 8 mm, bristle thickness: 2 mm), and then dried at room temperature for 1 hour to adsorb the mesoporous silica nanoparticles in multiple layers onto the acrylic resin substrate.

[0059] Next, an acrylic resin substrate with the mesoporous silica nanoparticles adsorbed in multiple layers on its surface was placed in a stainless steel pad with a lid (capacity: 3 L) together with chloroform (100 ml) and exposed to nearly saturated chloroform vapor at room temperature for 90 minutes. This plasticized the surface of the acrylic resin substrate, creating a polymeric fluid state and embedding the mesoporous silica nanoparticles in the surface of the acrylic resin substrate. Subsequently, the surface of the acrylic resin substrate, which was in a polymeric fluid state, was hardened by exposure to air for 15 minutes. Then, ultrasonic cleaning (frequency 42 kHz, output 100 W) was performed in ethanol for 30 seconds to obtain an acrylic resin substrate (anti-reflective member) having a particle layer on which the mesoporous silica nanoparticles were directly immobilized on the surface.

[0060] The cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 4 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 4 confirmed that the mesoporous silica nanoparticles were arranged in 2.3 to 2.7 layers on the surface of the resin substrate. Furthermore, the thickness of the particle layer consisting of the mesoporous silica nanoparticles was approximately 350 to 400 nm, which was about 2.3 to 2.7 times the average particle diameter of the mesoporous silica nanoparticles.

[0061] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 5 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. The AFM image shown in Figure 5 confirms that the surface of the resin substrate is not exposed, and that the surface of the resin substrate is almost 100% covered by the particle layer made of the mesoporous silica nanoparticles.

[0062] Next, the light transmittance of the obtained anti-reflective material and the untreated acrylic resin substrate were measured for comparison. Figure 6 shows the wavelength dependence of the light transmittance of the anti-reflective material and the untreated acrylic resin substrate. In the wavelength range of 800 to 1600 nm, it was confirmed that the obtained anti-reflective material showed improved light transmittance compared to the untreated acrylic resin substrate. Table 1 shows the light transmittance of the obtained anti-reflective material at wavelengths of 1250 nm and 1550 nm, and the difference in light transmittance with the untreated acrylic resin substrate at these wavelengths.

[0063] (Example 2) An acrylic resin substrate (anti-reflective member) having a particle layer on which the mesoporous silica nanoparticles are directly immobilized on the surface was fabricated in the same manner as in Example 1, except that the exposure time to chloroform vapor at a nearly saturated concentration was changed to 120 minutes.

[0064] The cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 7 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 7 confirmed that the mesoporous silica nanoparticles were arranged in 2.7 to 3.0 layers on the surface of the resin substrate. Furthermore, the thickness of the particle layer consisting of the mesoporous silica nanoparticles was approximately 400 to 450 nm, which was about 2.7 to 3.0 times the average particle diameter of the mesoporous silica nanoparticles.

[0065] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 8 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. The AFM image shown in Figure 8 confirms that the surface of the resin substrate is not exposed, and that the surface of the resin substrate is almost 100% covered by the particle layer made of the mesoporous silica nanoparticles.

[0066] Next, the light transmittance of the obtained anti-reflective material and the untreated acrylic resin substrate were measured for comparison. Figure 9 shows the wavelength dependence of the light transmittance of the anti-reflective material and the untreated acrylic resin substrate. In the wavelength range of 800 to 1600 nm, it was confirmed that the obtained anti-reflective material showed improved light transmittance compared to the untreated acrylic resin substrate. Table 1 shows the light transmittance of the obtained anti-reflective material at wavelengths of 1250 nm and 1550 nm, and the difference in light transmittance with the untreated acrylic resin substrate at these wavelengths.

[0067] (Example 3) A polyetherimide resin substrate (anti-reflective member) having a particle layer on which the mesoporous silica nanoparticles are directly immobilized was fabricated in the same manner as in Example 1, except that a flat polyetherimide resin substrate (a substrate obtained by smoothing a polyetherimide resin substrate "Duratron U1000PEI" (thickness: 0.8 mm) manufactured by Mitsubishi Chemical Advanced Materials Corporation) was used instead of the flat acrylic resin substrate, and the exposure time to chloroform vapor at a nearly saturated concentration was changed to 150 minutes.

[0068] The cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 10 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 10 confirmed that the mesoporous silica nanoparticles were arranged in 2.3 to 2.7 layers on the surface of the resin substrate. Furthermore, the thickness of the particle layer consisting of the mesoporous silica nanoparticles was approximately 350 to 400 nm, which was about 2.3 to 2.7 times the average particle diameter of the mesoporous silica nanoparticles.

[0069] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 11 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. The AFM image shown in Figure 11 confirms that the surface of the resin substrate is not exposed, and that the surface of the resin substrate is almost 100% covered by the particle layer made of the mesoporous silica nanoparticles.

[0070] Next, the light transmittance of the obtained anti-reflective material and, for comparison, the untreated polyetherimide resin substrate were measured. Figure 12 shows the wavelength dependence of the light transmittance of the anti-reflective material and the untreated polyetherimide resin substrate. In the wavelength range of 800 to 2100 nm, it was confirmed that the obtained anti-reflective material showed improved light transmittance compared to the untreated polyetherimide resin substrate. Table 1 shows the light transmittance of the obtained anti-reflective material at wavelengths of 1250 nm and 1550 nm, and the difference in light transmittance between it and the untreated polyetherimide resin substrate at those wavelengths.

[0071] (Example 4) An acrylic resin substrate (anti-reflective member) having a particle layer on which the mesoporous silica nanoparticles are directly immobilized was fabricated in the same manner as in Example 1, except that an acrylic resin substrate having a curved surface (radius of curvature: 1 cm) (an acrylic resin substrate "Acrypet" manufactured by Mitsubishi Chemical Corporation (thickness: 2 mm) that was bent by partial heating) was used instead of the flat acrylic resin substrate.

[0072] The appearance of the obtained anti-reflective material was observed. Figure 13 is a photograph showing the appearance of the obtained anti-reflective material. The photograph in Figure 13 confirms that a particle layer in which the mesoporous silica nanoparticles are uniformly and directly immobilized is formed even on the curved surface of the acrylic resin substrate.

[0073] Furthermore, the cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 14 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 14 confirmed that the mesoporous silica nanoparticles were arranged in 2.3 to 2.7 layers on the surface of the resin substrate. The thickness of the particle layer consisting of the mesoporous silica nanoparticles was approximately 350 to 400 nm, which was about 2.3 to 2.7 times the average particle diameter of the mesoporous silica nanoparticles.

[0074] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 15 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. The AFM image shown in Figure 15 confirms that the surface of the resin substrate is not exposed, and that the surface of the resin substrate is almost 100% covered by the particle layer made of the mesoporous silica nanoparticles.

[0075] (Example 5) An acrylic resin substrate (anti-reflective member) having a particle layer on which the mesoporous silica nanoparticles are directly immobilized was fabricated in the same manner as in Example 1, except that dichloromethane (100 ml) was used instead of chloroform and the exposure time to dichloromethane vapor at a nearly saturated concentration was changed to 180 minutes.

[0076] The cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 16 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 16 confirmed that the mesoporous silica nanoparticles were arranged in 2.3 to 3.0 layers on the surface of the resin substrate. Furthermore, the thickness of the particle layer consisting of the mesoporous silica nanoparticles was approximately 350 to 450 nm, which was about 2.3 to 3.0 times the average particle diameter of the mesoporous silica nanoparticles.

[0077] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 17 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. The AFM image shown in Figure 17 confirms that the surface of the resin substrate is not exposed, and that the surface of the resin substrate is almost 100% covered by the particle layer made of the mesoporous silica nanoparticles.

[0078] Next, the light transmittance of the obtained anti-reflective material and the untreated acrylic resin substrate were measured for comparison. Figure 18 shows the wavelength dependence of the light transmittance of the anti-reflective material and the untreated acrylic resin substrate. In the wavelength range of 800 to 1600 nm, it was confirmed that the obtained anti-reflective material showed improved light transmittance compared to the untreated acrylic resin substrate. Table 1 shows the light transmittance of the obtained anti-reflective material at wavelengths of 1250 nm and 1550 nm, and the difference in light transmittance with the untreated acrylic resin substrate at these wavelengths.

[0079] (Example 6) An acrylic resin substrate (anti-reflective member) having a particle layer on which the mesoporous silica nanoparticles are directly immobilized was fabricated in the same manner as in Example 1, except that acetone (100 ml) was used instead of chloroform and the exposure time to nearly saturated acetone vapor was changed to 210 minutes.

[0080] The cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 19 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 19 confirmed that the mesoporous silica nanoparticles were arranged in 2.7 to 3.3 layers on the surface of the resin substrate. Furthermore, the thickness of the particle layer consisting of the mesoporous silica nanoparticles was approximately 400 to 500 nm, which was about 2.7 to 3.3 times the average particle diameter of the mesoporous silica nanoparticles.

[0081] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 20 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. The AFM image shown in Figure 20 confirms that the surface of the resin substrate is not exposed, and that the surface of the resin substrate is almost 100% covered by the particle layer made of the mesoporous silica nanoparticles.

[0082] Next, the light transmittance of the obtained anti-reflective material and the untreated acrylic resin substrate were measured for comparison. Figure 21 shows the wavelength dependence of the light transmittance of the anti-reflective material and the untreated acrylic resin substrate. In the wavelength range of 800 to 1600 nm, it was confirmed that the obtained anti-reflective material showed improved light transmittance compared to the untreated acrylic resin substrate. Table 1 shows the light transmittance of the obtained anti-reflective material at wavelengths of 1250 nm and 1550 nm, and the difference in light transmittance with the untreated acrylic resin substrate at these wavelengths.

[0083] (Comparative Example 1) An acrylic resin substrate (anti-reflective member) having a particle layer on which the spherical silica nanoparticles are directly immobilized on the surface was prepared in the same manner as in Example 1, except that an ethanol dispersion (7 ml) containing 5% by mass of the surface hydrophobic spherical silica nanoparticles obtained in Preparation Example 2 was used instead of the ethanol dispersion containing the surface hydrophobic mesoporous silica nanoparticles.

[0084] The cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 22 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 22 confirmed that the spherical silica nanoparticles were arranged in approximately 3.3 layers on the surface of the resin substrate. Furthermore, the thickness of the particle layer consisting of the spherical silica nanoparticles was approximately 500 nm, which was about 3.3 times the average particle diameter of the spherical silica nanoparticles.

[0085] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 23 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. The AFM image shown in Figure 23 confirms that the surface of the resin substrate is not exposed, and that the surface of the resin substrate is almost 100% covered by the particle layer made of the spherical silica nanoparticles.

[0086] Next, the light transmittance of the obtained anti-reflective material and the untreated acrylic resin substrate were measured for comparison. Figure 24 shows the wavelength dependence of the light transmittance of the anti-reflective material and the untreated acrylic resin substrate. It was found that in the wavelength range of 800 to 1600 nm, the obtained anti-reflective material exhibited lower light transmittance compared to the untreated acrylic resin substrate. Table 1 shows the light transmittance of the obtained anti-reflective material at wavelengths of 1250 nm and 1550 nm, and the difference in light transmittance between it and the untreated acrylic resin substrate at these wavelengths.

[0087] (Comparative Example 2) An acrylic resin substrate (anti-reflective member) having a particle layer on which the mesoporous silica nanoparticles are directly immobilized on the surface was fabricated in the same manner as in Example 1, except that the exposure time to chloroform vapor at a nearly saturated concentration was changed to 30 minutes.

[0088] The cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 25 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 25 confirms that the mesoporous silica nanoparticles are arranged in a single layer on the surface of the resin substrate.

[0089] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 26 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. From the AFM image shown in Figure 26, the surface of the resin substrate is partially exposed, and the ratio of the area occupied by the particle layer made of mesoporous silica nanoparticles to the total surface area of ​​the resin substrate was calculated to be 82%.

[0090] Next, the light transmittance of the obtained anti-reflective material and the untreated acrylic resin substrate were measured for comparison. Figure 27 shows the wavelength dependence of the light transmittance of the anti-reflective material and the untreated acrylic resin substrate. In the wavelength range of 800 to 1600 nm, the obtained anti-reflective material showed a slight improvement in light transmittance compared to the untreated acrylic resin substrate, but the effect was less significant than when the mesoporous silica nanoparticles were adsorbed in multiple layers (Examples 1-2). Table 1 shows the light transmittance of the obtained anti-reflective material at wavelengths of 1250 nm and 1550 nm, and the difference in light transmittance compared to the untreated acrylic resin substrate at those wavelengths.

[0091] (Comparative Example 3) An acrylic resin substrate (anti-reflective member) having a particle layer on which the mesoporous silica nanoparticles are directly immobilized was prepared in the same manner as in Example 1, except that an acrylic resin substrate on which the mesoporous silica nanoparticles are adsorbed in multiple layers on the surface was exposed for 48 hours to chloroform vapor (vapor concentration: approximately 4.1% (20% of saturation concentration)) obtained by completely vaporizing the chloroform under a sealed environment with the amount of chloroform changed to 0.43 ml (0.63 g) of chloroform.

[0092] The cross-section of the obtained anti-reflective material was observed using a scanning electron microscope (SEM). Figure 28 shows a scanning electron microscope image (SEM image) of the cross-section of the obtained anti-reflective material. The SEM image shown in Figure 28 confirms that the mesoporous silica nanoparticles are arranged in a single layer on the surface of the resin substrate.

[0093] Furthermore, the surface of the obtained anti-reflective material was observed using an atomic force microscope (AFM). Figure 29 shows an atomic force microscope image (AFM image) of the surface of the obtained anti-reflective material. From the AFM image shown in Figure 29, the surface of the resin substrate is partially exposed, and the ratio of the area occupied by the particle layer made of mesoporous silica nanoparticles to the total surface area of ​​the resin substrate was calculated to be 69%.

[0094] Next, the light transmittance of the obtained anti-reflective material and the untreated acrylic resin substrate were measured for comparison. Figure 30 shows the wavelength dependence of the light transmittance of the anti-reflective material and the untreated acrylic resin substrate. In the wavelength range of 800 to 1600 nm, the obtained anti-reflective material showed a slight improvement in light transmittance compared to the untreated acrylic resin substrate, but the effect was less significant than when the mesoporous silica nanoparticles were adsorbed in multiple layers (Examples 1-2). Table 1 shows the light transmittance of the obtained anti-reflective material at wavelengths of 1250 nm and 1550 nm, and the difference in light transmittance compared to the untreated acrylic resin substrate at these wavelengths.

[0095]

[0096] As described above, the present invention makes it possible to obtain an anti-reflective member having excellent anti-reflective performance (e.g., high light transmittance) in the near-infrared wavelength range. Therefore, because the anti-reflective member of the present invention has excellent anti-reflective performance in the near-infrared wavelength range, it is useful as an anti-reflective member used in infrared-using devices such as infrared cameras, infrared communication devices, home appliance remote controls, and vein authentication devices, for components that need to transmit infrared light, such as lenses, window materials, and connectors.

Claims

1. An anti-reflective member comprising a resin substrate and a particle layer made of mesoporous silica nanoparticles disposed on the surface of the resin substrate, wherein some of the nanoparticles are directly fixed to the surface of the resin substrate, and at least some of the nanoparticles directly fixed to the surface of the resin substrate are embedded in the surface of the resin substrate, the nanoparticles are arranged in two or more layers to form the particle layer, the thickness of the particle layer is 2 to 10 times the average particle diameter of the nanoparticles, and the ratio of the area occupied by the particle layer made of nanoparticles to the total surface area of ​​the resin substrate is 95% or more.

2. The anti-reflective member according to claim 1, wherein the average particle size of the nanoparticles is 50 to 300 nm.

3. The anti-reflective member according to claim 1, wherein the mesoporous silica nanoparticles are surface hydrophobic mesoporous silica nanoparticles.

4. The anti-reflective member according to claim 1, wherein the mesoporous silica nanoparticles are nanoparticles having a porosity of 20 to 70%.

5. The anti-reflective member according to claim 1, wherein the resin substrate is made of a transparent resin.

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