Antireflection glass

Abstract

An anti-reflective glass comprises, in sequence, a glass substrate, an anti-reflective film, and a protective layer. The anti-reflective film, starting from the glass substrate side, is constructed in the following order: a low-to-medium refractive index layer with a refractive index of 1.36–1.45 and a thickness of 150–210 nm; a medium refractive index layer with a refractive index of 1.56–1.79 and a thickness of 90–140 nm; a high refractive index layer with a refractive index of 1.75–1.87 and a thickness of 30–50 nm; and a low refractive index layer with a refractive index of 1.27–1.35 and a thickness of 70–75 nm. The high refractive index layer has a higher refractive index than the medium refractive index layer. The refractive index of the aforementioned protective layer is 1.43 to 1.48, and the layer thickness is 20 to 30 nm. The aforementioned high refractive index layer, low refractive index layer, and protective layer contain (A) aluminum hydrate. The average light reflectance of both sides at wavelengths of 380 to 780 nm is less than 0.6%, and the average light transmittance at wavelengths of 380 to 780 nm is more than 98%. This anti-reflective glass has high anti-reflective performance, excellent alkali resistance, and is suitable for the manufacture of anti-reflective tempered glass.

Description

Technical Field

[0001] This invention relates to anti-reflective glass, which is suitable for the manufacture of anti-reflective tempered glass and is endowed with high anti-reflective properties. Background Technology

[0002] Tempered glass, with its increased strength, is widely used in automotive and residential window glass, and has recently been applied to full-coverage protective panels for electrostatic capacitive touch panels, displays for digital cameras, portable phones, and other mobile devices.

[0003] The latter type of tempered glass has small and complex shapes, requiring cutting, end-face processing, and hole-making. However, these shaping processes are difficult to perform after tempering, so the glass substrate is pre-processed into the final product shape before tempering.

[0004] As methods for strengthening glass, physical strengthening using rapid cooling and chemical strengthening using ion exchange are known. Physical strengthening methods are suitable for glass with a thickness of several millimeters or more, but are ineffective for thin glass substrates. Therefore, for thin-walled glass such as protective panels and displays, chemical strengthening methods are typically used.

[0005] Chemical strengthening using ion exchange involves replacing metal ions with smaller ionic radii (e.g., sodium ions) in the glass with metal ions with larger ionic radii (e.g., potassium ions). In other words, by replacing metal ions with smaller ionic radii, a compressive stress layer is formed on the glass surface.

[0006] As a result, in order to break this glass, in addition to the force that breaks the bonds between molecules, the force that removes the compressive stress on the surface is also required, and its strength is obviously significantly improved compared to ordinary glass.

[0007] However, even tempered glass, which has been strengthened through chemical treatment using ion exchange, sometimes requires other functions such as anti-reflective properties, especially for the aforementioned protective panels, various displays, and other applications where high anti-reflective properties are required.

[0008] To impart anti-reflective properties, a low-refractive-index anti-reflective film can be formed on the glass surface. Known methods for forming such anti-reflective films are broadly categorized into vapor deposition and sol-gel methods.

[0009] Evaporation deposition is not widely implemented in industry due to the need for extremely expensive equipment. Currently, the sol-gel method, which involves coating a solution containing fine particles and forming an antireflective film through gelation using heat treatment, has become the mainstream method due to its low production cost and high production volume.

[0010] As an antireflective film formed using this sol-gel method, antireflective films containing hydrolyzed condensates of silicon compounds, metal chelate compounds, and low-refractive-index silica particles are known (see Patent Document 1).

[0011] There are significant problems that must be solved in forming an anti-reflective film on the surface of chemically treated tempered glass.

[0012] Previously, after the anti-reflective coating was formed, strengthening treatment could not be carried out because potassium ions could not penetrate into the glass. Therefore, the anti-reflective coating had to be formed on each product that had undergone shaping and strengthening treatment. At this time, the advantages of the sol-gel method, which could achieve large-area processing, were completely lost, and productivity was significantly reduced.

[0013] To address the aforementioned issues, a method for strengthening glass through chemical treatment after the formation of the antireflective coating has been proposed.

[0014] One method involves strengthening glass by using the interparticle spaces (hereinafter referred to as voids) between inorganic fine particles contained in an antireflective film formed on the surface for ion exchange (Patent Document 2). However, this method suffers from the problem of difficulty in controlling the voids that allow for ion exchange.

[0015] To address the aforementioned issues, a method has been proposed that utilizes hollow particles with internal spaces for ion exchange, rather than the gaps between particles (Patent Document 3). This method, by using particles with a pre-defined spatial volume, makes setting the ion exchange conditions easier compared to the aforementioned gap-based method. However, on the other hand, hollow inorganic particles are mostly nonexistent or their industrial manufacturing methods are limited, thus restricting the types of inorganic particles that can be used.

[0016] To improve its anti-reflective performance, multi-layer anti-reflective films have been developed, which include a low-refractive-index layer, a high-refractive-index layer, and then a medium-refractive-index layer.

[0017] In order to exhibit the specified refractive index in these high-refractive-index and medium-refractive-index layers, zirconium oxide and titanium oxide particles, which have higher refractive indices than silica particles, must be mixed in. However, it is difficult to obtain hollow particles for these high-refractive-index particles, thus preventing the aforementioned ion exchange utilizing the internal space of the particles. When the antireflective film is multilayered, it is difficult to perform glass strengthening treatment by utilizing ion exchange through multiple refractive index layers after forming the antireflective film under normal conditions.

[0018] The inventors of this application first conducted in-depth research and proposed a method for manufacturing anti-reflective reinforced glass having such a multi-layered anti-reflective film (Patent Document 4).

[0019] Existing technical documents

[0020] Patent documents

[0021] Patent Document 1: Japanese Patent Application Publication No. 2002-221602

[0022] Patent Document 2: Japanese Patent Application Publication No. 2002-234754

[0023] Patent Document 3: Japanese Patent Application Publication No. 2011-88765

[0024] Patent Document 4: Japanese Patent Application Publication No. 2017-178634 Summary of the Invention

[0025] The problem the invention aims to solve

[0026] The inventors of this application faced the following problems during the development of anti-reflective reinforced glass.

[0027] For tempered glass, an alkaline cleaning process is required to remove organic / inorganic substances adhering to the glass surface to improve the adhesion between the tempered glass and the anti-reflective film, and to prevent the tempered glass from becoming frosted and losing its transparency after commercialization (to prevent burns). Furthermore, alkaline cleaning is performed for various purposes, such as removing impurities that adhere during glass tempering.

[0028] Specifically, burns include: a bluish tinge caused by the lack of alkali ions on the glass surface due to the erosion of moisture in the air; and a whitening tinge caused by the drying and concentration of moisture containing alkali ions on the glass surface and the formation of carbonic acid compounds from carbon dioxide. These burns are difficult to repair once they occur without physical surface polishing.

[0029] However, due to this alkaline cleaning, problems arise such as damage to the anti-reflective film formed on the glass surface, resulting in a mottled appearance, unevenness, reduced film thickness, failure to exhibit the desired anti-reflective properties, or color changes that render the product unusable.

[0030] Solution for solving the problem

[0031] The inventors of this application investigated the causes of deterioration of antireflective films due to alkaline cleaning and discovered that the presence of aluminum hydrate in the antireflective film can prevent deterioration by exhibiting alkali resistance, thus completing this invention.

[0032] That is, the present invention provides an anti-reflective glass, characterized in that it sequentially comprises a glass substrate, an anti-reflective film, and a protective layer.

[0033] The aforementioned anti-reflective film extends from the aforementioned glass substrate side.

[0034] A medium-to-low refractive index layer with a refractive index of 1.36–1.45 and a thickness of 150–210 nm.

[0035] A medium refractive index layer with a refractive index of 1.56–1.79 and a thickness of 90–140 nm.

[0036] A high refractive index layer with a refractive index of 1.75–1.87 and a thickness of 30–50 nm.

[0037] A low-refractive-index layer with a refractive index of 1.27–1.35 and a thickness of 70–75 nm.

[0038] The layers are arranged in a specific order, with the high-refractive-index layer having a higher refractive index than the intermediate-refractive-index layer.

[0039] The aforementioned protective layer has a refractive index of 1.43–1.48 and a thickness of 20–30 nm.

[0040] The aforementioned high-refractive-index layer, low-refractive-index layer, and protective layer contain (A) aluminum hydrate.

[0041] The average light reflectance of both sides in the wavelength range of 380–780 nm is less than 0.6%, and the average light transmittance in the wavelength range of 380–780 nm is more than 98%.

[0042] In the invention of the aforementioned anti-reflective glass, the preferred embodiment is:

[0043] 1) Furthermore, the aforementioned low-to-medium refractive index layer and medium refractive index layer contain (A) aluminum hydrate;

[0044] 2) The aforementioned protective layer is formed from a cured protective layer composition, wherein, relative to 100 parts by mass of the binder component (B) formed from the alkoxysilane compound or its hydrolysate as shown in formula (1), the protective layer composition contains 3 to 25 parts by mass of (A) aluminum hydrate and 1 to 20 parts by mass of (C) metal chelate compound.

[0045] R n -Si(OR 1 ) 4-n (1)

[0046] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2);

[0047] 3) The aforementioned low refractive index layer is formed from a cured low refractive index layer composition, wherein, relative to 100 parts by mass of the binder component (B) formed from the alkoxysilane compound or its hydrolysate as shown in formula (1), the low refractive index layer composition contains 3-25 parts by mass of (A) aluminum hydrate, 1-20 parts by mass of (C) metal chelate compound, and 25-90 parts by mass of (D) silica particles.

[0048] R n -Si(OR 1 ) 4-n (1)

[0049] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2);

[0050] 4) The aforementioned high refractive index layer is formed from a cured high refractive index layer composition, wherein the high refractive index layer composition contains, relative to 100 parts by mass of (B) the binder component formed from the alkoxysilane compound or its hydrolysate shown in formula (1), 1 to 15 parts by mass of (A) aluminum hydrate and 40 to 130 parts by mass of (E) metal oxide particles.

[0051] R n -Si(OR 1 ) 4-n (1)

[0052] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2);

[0053] 5) The aforementioned intermediate refractive index layer is formed from a cured intermediate refractive index layer composition, wherein the intermediate refractive index layer composition contains, relative to 100 parts by mass of (B) the binder component formed from the alkoxysilane compound or its hydrolysate shown in formula (1), 1-15 parts by mass of (A) aluminum hydrate and 40-130 parts by mass of (E) metal oxide particles.

[0054] R n -Si(OR 1 ) 4-n (1)

[0055] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2);

[0056] 6) The aforementioned low-to-medium refractive index layer is formed from a cured product of the low-to-medium refractive index layer composition, wherein the low-to-medium refractive index layer composition contains, relative to 100 parts by mass of (B) the binder component formed from the alkoxysilane compound or its hydrolysate shown in formula (1), 3-25 parts by mass of (A) aluminum hydrate, 1-20 parts by mass of (C) metal chelate compound, and 25-90 parts by mass of (D) silica particles.

[0057] R n -Si(OR 1 ) 4-n (1)

[0058] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2);

[0059] 7) The aforementioned glass substrate is alkali aluminosilicate glass;

[0060] 8) The aforementioned anti-reflective glass is an anti-reflective glass that is chemically strengthened to resist alkali.

[0061] It should be noted that the mass fraction of silica particles in each of the above layers refers to either solid silica particles or hollow silica particles, or the total mass fraction. Additionally, the mass fraction of metal oxide particles in each of the above layers can be the mass fraction of one type of metal oxide particle, or the total mass fraction of two or more different types of metal oxide particles.

[0062] Furthermore, the invention provides a method for manufacturing anti-reflective strengthened glass, characterized in that it includes a step of chemically strengthening the anti-reflective glass in an ion-exchange metal salt molten solution; and a step of alkaline cleaning before or after the chemical treatment step.

[0063] The effects of the invention

[0064] The antireflective glass provided by this invention is suitable for manufacturing antireflective strengthened glass with high antireflective properties. Specifically, after forming an antireflective film on the surface of a glass substrate, the glass can be strengthened by alkaline cleaning and a one-time strengthening treatment, which is useful for the industrial manufacturing of high-quality antireflective strengthened glass with excellent smoothness and transparency.

[0065] Glass strengthening through chemical treatment utilizes the internal voids of hollow silica particles or the interstitial spaces between oxide particles to achieve strengthening in a single process. Furthermore, due to its excellent alkali resistance, this antireflective glass can prevent a decrease in antireflective performance caused by unevenness or reduction in film thickness, even after surface smoothing and alkaline cleaning processes required to prevent burns.

[0066] As a result, high-quality anti-reflective tempered glass products with excellent anti-reflective properties, smoothness, and no reduction in transparency can be manufactured with extremely high productivity and low cost. The resulting anti-reflective tempered glass, due to its multi-layered anti-reflective coating, exhibits low reflectivity and excellent anti-reflective performance across a wide range of wavelengths of light.

[0067] This type of anti-reflective tempered glass is suitable for use in products with thin glass substrates, such as front protective panels for electrostatic capacitive touch panels, displays for various mobile devices such as digital cameras and mobile phones. Detailed Implementation

[0068] Anti-reflective glass

[0069] The anti-reflective glass of the present invention is basically composed of a glass substrate, an anti-reflective film and a protective layer, which are stacked in this order.

[0070] The aforementioned anti-reflective film extends from the aforementioned glass substrate side.

[0071] A medium-to-low refractive index layer with a refractive index of 1.36–1.45 and a thickness of 150–210 nm.

[0072] A medium refractive index layer with a refractive index of 1.56–1.79 and a thickness of 90–140 nm.

[0073] A high refractive index layer with a refractive index of 1.75–1.87 and a thickness of 30–50 nm.

[0074] A low-refractive-index layer with a refractive index of 1.27–1.35 and a thickness of 70–75 nm.

[0075] The high-refractive-index layer is configured in a specific order, with its refractive index set higher than that of the intermediate-refractive-index layer.

[0076] The refractive index of the protective layer is 1.43–1.48, and the thickness is 20–30 nm.

[0077] This anti-reflective glass has the characteristics of an average light reflectance of less than 0.6% on both sides in the wavelength range of 380 to 780 nm, and an average light transmittance of more than 98% in the wavelength range of 380 to 780 nm.

[0078] The most significant feature of this invention is that it contains (A) aluminum hydrate in the aforementioned high-refractive-index layer, low-refractive-index layer, and protective layer. By containing (A) aluminum hydrate in these layers, the anti-reflective glass exhibits alkali resistance, preventing deterioration and damage to the anti-reflective film. While the presence of (A) aluminum hydrate in at least the high-refractive-index layer, low-refractive-index layer, and protective layer is sufficient to impart alkali resistance, it is preferable to further include it in the medium-refractive-index layer and the medium-low-refractive-index layer, as this significantly improves alkali resistance.

[0079] <Glass substrate>

[0080] There are no particular restrictions on whether the glass substrate is a glass with a composition that can be strengthened by chemical treatment, but it is preferred to be a glass containing alkali metal ions or alkaline earth metal ions with smaller ionic radii.

[0081] Specifically, examples include soda-lime silicate glass, alkali aluminosilicate glass, and alkali borosilicate glass. Among these, glass containing sodium ions is preferred, and glass containing more than 5% sodium ions by weight is most preferred.

[0082] Considering the higher potassium ion replacement rate resulting in a deeper strengthening layer and the higher transparency, alkali aluminosilicate glass is preferred.

[0083] The thickness of the glass substrate is typically 0.2 mm to 2 mm. If it exceeds 2 mm, the strength of the glass may be insufficient for tempering, making it unsuitable for chemical strengthening using ion exchange. There are no particular restrictions on the substrate area; it can be arbitrarily determined by the size of the final product and the limitations of the manufacturing process.

[0084] Anti-reflective film

[0085] An anti-reflective film is typically laminated on the aforementioned glass substrate. However, in order to improve antistatic properties, anti-glare properties, and sealing, and to prevent light from passing through the visible area, an antistatic layer, a silica particle layer, a primer layer, or a smoke layer may be provided between the glass substrate and the anti-reflective film, or between adjacent refractive index layers of any of the following.

[0086] The antireflective film in this invention is a multilayer antireflective film composed of four refractive index layers having the following characteristics.

[0087] Medium to low refractive index layer: refractive index 1.36–1.45, layer thickness 150–210 nm

[0088] Medium refractive index layer: refractive index 1.56–1.79, layer thickness 90–140 nm

[0089] High refractive index layer: refractive index 1.75–1.87, layer thickness 30–50 nm

[0090] Low refractive index layer: refractive index 1.27–1.35, layer thickness 70–75 nm

[0091] It should be noted that the refractive index of the high refractive index layer is set to be higher than that of the medium refractive index layer.

[0092] The four refractive index layers are arranged in the following order from the glass substrate side: low-to-medium refractive index layer, medium refractive index layer, high refractive index layer, and low refractive index layer.

[0093] By forming the above four layers of anti-reflective film, the average light reflectance of both sides of the anti-reflective glass and the anti-reflective tempered glass in the wavelength range of 380-780nm is less than 0.6%, and the average light transmittance in the wavelength range of 380-780nm is more than 98%, thus obtaining high-performance anti-reflective products.

[0094] The values ​​of average light reflectance and average light transmittance mentioned above are the values ​​before glass strengthening, but they are maintained and performed after glass strengthening.

[0095] <Medium and low refractive index layer>

[0096] It is the refractive index layer located at the bottom (glass substrate side) of the antireflective coating. It is usually laminated on the glass substrate.

[0097] The refractive index of the low-to-medium refractive index layer is 1.36–1.45, and the layer thickness is 150–210 nm. Preferably, the refractive index is 1.38–1.43, and the layer thickness is 170–205 nm.

[0098] Since the medium-low refractive index layer needs to be strengthened by chemical treatment after the formation of the anti-reflective film and the protective layer, it is preferable to prepare a solution containing the following components, cover the solution, and dry and heat it to form the medium-low refractive index layer.

[0099] Relative to (B) 100 parts by mass of the binder component formed from the alkoxysilane compound or its hydrolysate (hereinafter referred to as "alkoxysilane compound, etc.") shown in formula (1),

[0100] R n -Si(OR 1 ) 4-n (1)

[0101] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2)

[0102] (A) 3-25 parts by weight of aluminum hydrate

[0103] (C) 1-20 parts by weight of metal chelate compound, and

[0104] (D) 25-90 parts by weight of silica particles

[0105] If the low-to-medium refractive index layer does not contain (A) aluminum hydrate, it is sufficient to exclude (A) aluminum hydrate from the above-mentioned low-to-medium refractive index layer composition.

[0106] [Alkoxysilane compounds or their hydrolysates]

[0107] The components that function as an adhesive for forming a dense and high-strength film with good adhesion to a glass substrate are represented by the above formula (1).

[0108] In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group.

[0109] The alkyl group preferably has 1 to 9 carbon atoms, more preferably 1 to 5. Examples of alkyl groups include methyl, ethyl, trimethyl, propyl, butyl, tetramethyl, pentyl, and hexyl.

[0110] The number of carbon atoms in the alkenyl group is preferably 1 to 9, more preferably 1 to 5. Examples of alkenyl groups include vinyl, propenyl, butenyl, pentenyl, and hexenyl.

[0111] The number of carbon atoms in the alkoxyalkyl group is preferably 1 to 9, more preferably 1 to 5. Examples of alkoxy groups include methoxy, ethoxy, and propoxy. Examples of alkyl groups include methyl, ethyl, trimethyl, propyl, butyl, tetramethyl, pentyl, and hexyl.

[0112] In the formula, R 1 It is an alkyl, alkoxyalkyl, acyloxy, or halogen atom.

[0113] Alkyl and alkoxyalkyl are the same as R, respectively.

[0114] The number of carbon atoms in the acyloxy group is preferably 1 to 9, more preferably 1 to 5. Examples of acyloxy groups include acetoxy and benzoyloxy.

[0115] Examples of halogen atoms include fluorine, chlorine, bromine, and iodine.

[0116] [Aluminum salt hydrate]

[0117] For the antireflective glass of the present invention to exhibit alkali resistance, the aluminum hydrate must be present in the protective layer and in the low-refractive-index layer and high-refractive-index layer located on the upper layer (viewing side) of the reflective film. Furthermore, it is preferable that the aluminum hydrate is also present in the medium-refractive-index layer and the medium-low-refractive-index layer located on the lower layer (glass substrate side) of the reflective film due to the extremely increased alkali resistance.

[0118] Aluminum hydrates are hydrated compounds formed by adding water molecules to aluminum salts in the form of crystal water, coordinated water, etc. In the case of non-hydrates, due to a lack of affinity with other components, aggregation or precipitation may sometimes occur during mixing. Especially in the case of anhydrous salts with hygroscopic properties, the low-to-medium refractive index composition solution (described later) may react with moisture in the air during coating, making it difficult to achieve uniformity and form a low-to-medium refractive index layer. Furthermore, when using other metal hydrates, alkali resistance is lacking. Aluminum hydrates are used for other refractive index layers for the same reasons.

[0119] It is speculated that aluminum is a metal that can coordinate with the aforementioned binder components, and it will generate aluminum oxide in the refractive index layer that is not easily penetrated by alkali, thus exhibiting alkali resistance.

[0120] Representative aluminum hydrates include aluminum chloride trihydrate, aluminum chloride hexahydrate, aluminum bromide hexahydrate, aluminum nitrate hexahydrate, aluminum nitrate nonahydrate, aluminum hydroxide trihydrate, aluminum acetate n-hydrate, and aluminum sulfate n-hydrate. Considering the performance of alkali resistance and scratch resistance, aluminum chloride trihydrate and aluminum chloride hexahydrate are particularly preferred.

[0121] When the low-to-medium refractive index layer contains aluminum hydrate, the amount should be 3 to 25 parts by mass relative to 100 parts by mass of the aforementioned alkoxysilane compound, etc. Less than 3 parts by mass will not produce the desired effect. If more than 25 parts by mass, the bonding strength of the aforementioned alkoxysilane compound, etc., and the hardness of the low-to-medium refractive index layer decrease, therefore this is not preferred.

[0122] [Metal chelate compounds]

[0123] It is a component that functions as a crosslinking agent, making the formed refractive index layer denser.

[0124] The metal chelate compound (C) is a compound formed by chelating agents, represented by bidentate ligands, in metals such as titanium, zirconium, and aluminum.

[0125] Specifically, titanium chelate compounds such as triethoxy-mono(acetylacetone)titanium, diethoxy-bis(acetylacetone)titanium, monoethoxy-tri(acetylacetone)titanium, tetra(acetylacetone)titanium, triethoxy-mono(ethyl acetoacetate)titanium, diethoxy-bis(ethyl acetoacetate)titanium, monoethoxy-tri(ethyl acetoacetate)titanium, mono(acetylacetone)tri(ethyl acetoacetate)titanium, bis(acetylacetone)bis(ethyl acetoacetate)titanium, and tri(acetylacetone)mono(ethyl acetoacetate)titanium can be listed;

[0126] Zirconium chelate compounds including triethoxy-mono(acetylacetone)zirconium, diethoxy-bis(acetylacetone)zirconium, monoethoxy-tri(acetylacetone)zirconium, tetra(acetylacetone)zirconium, triethoxy-mono(ethyl acetoacetate)zirconium, diethoxy-bis(ethyl acetoacetate)zirconium, monoethoxy-tri(ethyl acetoacetate)zirconium, tetra(ethyl acetoacetate)zirconium, mono(acetylacetone)tri(ethyl acetoacetate)zirconium, bis(acetylacetone)bis(ethyl acetoacetate)zirconium, tri(acetylacetone)mono(ethyl acetoacetate)zirconium;

[0127] Aluminum chelate compounds such as diethoxy-mono(acetylacetone)aluminum, monoethoxy-bis(acetylacetone)aluminum, di-isopropoxy-mono(acetylacetone)aluminum, monoethoxy-bis(ethyl acetoacetate)aluminum, diethoxy-mono(ethyl acetoacetate)aluminum, tri(acetylacetone)aluminum, etc.

[0128] The aforementioned metal chelate compound is used in a ratio of 1 to 20 parts by mass, preferably 3 to 15 parts by mass, relative to 100 parts by mass of (B) alkoxysilane compound, etc. If the ratio exceeds 20 parts by mass, the metal chelate compound tends to precipitate in the low-to-medium refractive index layer, potentially causing a decrease in anti-reflective properties and poor appearance. If the ratio is less than 1 part by mass, there is a tendency for a decrease in the strength and hardness of the low-to-medium refractive index layer.

[0129] [Silica particles]

[0130] In the low-refractive-index layer of the present invention, silica particles are used to control the refractive index to 1.36 to 1.45. As these silica particles, two types of silica particles are used: solid silica particles and hollow silica particles.

[0131] Solid silica particles are defined as particles with silica as the main component, a density of 1.9 or higher, an average particle size of 5–500 nm, and a refractive index in the range of 1.44–1.5, without internal voids. It should be noted that, in this invention, the average particle size refers to the particle size at which the cumulative volume is 50% in the particle size distribution determined by laser diffraction / scattering.

[0132] Hollow silica particles are silica particles with internal cavities, typically fine hollow particles with a particle size of 5–150 nm and an outer shell thickness of approximately 1–15 nm. They are used to perform ion exchange through their internal cavities, forming a layer with a refractive index of 1.36–1.45, thus exhibiting excellent anti-reflective properties. Therefore, hollow silica particles with a refractive index in the range of 1.20–1.38 are preferred.

[0133] Hollow silica particles are known, for example, through Japanese Patent Application Publication No. 2001-233611, and are generally commercially available in the form of dispersions formed by dispersing in lower alcohols such as methanol, ethanol, and propanol. Therefore, it is preferable to obtain commercially available products for use.

[0134] The aforementioned silica particles comprise 25 to 90 parts by mass relative to 100 parts by mass of (B) alkoxysilane compounds, etc. Preferably, the selection is appropriate, taking into account factors such as refractive index changes due to thermal processes and refractive index balance with the intermediate / high refractive index layer, within the range of 25 to 60 parts by mass of solid silica particles and 0 to 30 parts by mass of hollow silica particles, to satisfy the aforementioned specified refractive index. In particular, the inclusion of solid silica particles is preferred from the viewpoint of suppressing the shrinkage of alkoxysilane compounds, etc., due to thermal processes.

[0135] [Solution for forming medium-to-low refractive index layers]

[0136] The aforementioned components constituting the low-to-medium refractive index layer, along with any other components as needed, are dissolved in the following organic solvent for the purposes of viscosity adjustment and ease of coating, to prepare a solution for forming the low-to-medium refractive index layer. In this solution, to promote the hydrolysis and condensation of alkoxysilane compounds, etc., an acidic aqueous solution such as hydrochloric acid can be mixed in an appropriate amount.

[0137] Representative organic solvents include alcohol-based solvents such as methanol, ethanol, isopropanol, ethyl cellosolve, and ethylene glycol; ester-based solvents such as ethyl acetate and butyl acetate; ketone-based solvents such as acetone and methyl ethyl ketone; and aromatic solvents such as toluene and xylene. Alcohol-based solvents are particularly preferred. It should be noted that when using commercially available silica particle dispersions, the dispersion medium will inevitably be mixed into the solution used to form the low-to-medium refractive index layer. The dispersion medium in this solution, along with any separately mixed organic solvents, will be removed during the subsequent drying and heat curing processes.

[0138] The amount of organic solvent used should be such that the viscosity of the solution used does not cause sagging or other issues suitable for the coating range. Generally, an amount of organic solvent of 0.1 to 20% by weight of the total solid content is sufficient. It should be noted that this amount of organic solvent includes the amount of the dispersion medium such as silica particles.

[0139] [Formation of medium- and low-refractive-index layers]

[0140] The aforementioned solution for forming the low-to-medium refractive index layer is applied to the glass substrate, dried, and then cured by heating to form the low-to-medium refractive index layer. However, from the viewpoint of productivity and the adhesion of each layer of the antireflective film, the heat curing process using heat is preferably performed in one step after applying and drying the medium-to-medium refractive index layer, high-to-medium refractive index layer, and low-to-medium refractive index layer as described later. Furthermore, it is particularly preferable to heat-cure all layers of the antireflective film and the protective layer at once after applying and drying the same solution up to the protective layer.

[0141] There are no particular restrictions on the coating method. Methods such as dip coating, roller coating, die coating, flow coating, and spray coating can be used. However, from the perspective of appearance quality and layer thickness control, dip coating is preferred.

[0142] Drying is typically carried out at atmospheric temperatures of 70–100°C for 0.25–1 hour. Heating for thermosetting is typically carried out at atmospheric temperatures of 300–500°C for 0.5–2 hours.

[0143] <Medium Refractive Index Layer>

[0144] The refractive index layer is stacked on top of the aforementioned low- to medium-refractive-index layer (viewing side).

[0145] The refractive index of the intermediate refractive index layer is 1.56–1.79, and the layer thickness is 90–140 nm. Preferably, the refractive index is 1.58–1.76, and the layer thickness is 95–135 nm.

[0146] Since the medium refractive index layer needs to be strengthened by chemical treatment after the formation of the antireflective film and the protective layer, it is preferable to prepare a solution containing the following components, cover the solution, and dry and heat it to form the medium refractive index layer.

[0147] Relative to (B) 100 parts by mass of the binder component formed from the alkoxysilane compound or its hydrolysate (hereinafter referred to as "alkoxysilane compound, etc.") shown in formula (1),

[0148] R n -Si(OR 1 ) 4-n (1)

[0149] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2)

[0150] (A) 1-15 parts by weight of aluminum hydrate, and

[0151] (E) 40-130 parts by weight of metal oxide particles

[0152] If the intermediate refractive index layer does not contain (A) aluminum hydrate, it is sufficient to exclude (A) aluminum hydrate from the above intermediate refractive index layer composition.

[0153] [Alkoxysilane compounds or their hydrolysates]

[0154] The compound represented by formula (1) above is as described in the section on low and medium refractive index layers. Alkoxysilane compounds, etc., used in the formation of low and medium refractive index layers can be used in the same way for the same purpose.

[0155] [Aluminum salt hydrate]

[0156] As a component that contributes to alkali resistance in this invention, the aluminum hydrate is preferably present simultaneously in both the low-to-medium refractive index layer and the medium refractive index layer. The aluminum hydrate used in the formation of the low-to-medium refractive index layer can also be used in the same manner.

[0157] In the medium refractive index layer, if aluminum hydrate is present, it is contained in an amount of 1 to 15 parts by mass relative to 100 parts by mass of the aforementioned alkoxysilane compound, etc. Less than 1 part by mass is insufficient to achieve the desired effect. If it exceeds 15 parts by mass, it is difficult to form a layer due to easy reaction with moisture in the air during coating, and therefore is not preferred.

[0158] [Metal oxide particles]

[0159] In the intermediate refractive index layer, metal oxide particles are mixed in order to control the refractive index as specified above.

[0160] As metal oxide particles, metal oxide particles with a refractive index of 1.50 or higher can be used. For example, at least one oxide particle selected from the group consisting of titanium oxide, zirconium oxide, niobium pentoxide, antimony-doped tin oxide (ATO), indium tin oxide (ITO), phosphorus-doped tin oxide (PTO), fluorine-doped tin oxide (FTO), and antimony pentoxide is preferred.

[0161] Specifically, the metal oxide particles used include zirconium oxide particles (refractive index = 2.40), composite zirconium oxide particles (refractive index = 2.71) where the refractive index is adjusted by molecularly combining zirconium oxide with other oxides such as silicon oxide, titanium oxide particles, and composite titanium oxide particles (refractive index = 2.71) where the refractive index is adjusted by molecularly combining titanium oxide with other oxides such as silicon oxide and zirconium oxide. These metal oxide particles are appropriately combined to adjust to the desired refractive index. Such particles are well-known and commercially available.

[0162] The average particle size of the metal oxide particles is preferably 1–100 nm, more preferably 1–70 nm. The refractive index of the metal oxide particles is preferably 1.70–2.80, more preferably 1.90–2.50.

[0163] The content of metal oxide particles in the intermediate refractive index layer composition is 40 to 130 parts by mass relative to 100 parts by mass of alkoxysilane compounds, preferably appropriately selected from a range of 40 to 90 parts by mass of zirconium oxide particles and 0 to 40 parts by mass of titanium oxide particles, taking into account the refractive index change due to thermal process, etc., to meet the aforementioned specified refractive index. In particular, the inclusion of zirconium oxide particles is preferred from the viewpoint of suppressing the shrinkage of alkoxysilane compounds due to thermal process.

[0164] [Solution for forming a medium refractive index layer]

[0165] The aforementioned components constituting the low-to-medium refractive index layer, along with any other components such as an acidic aqueous solution as needed, are dissolved in the aforementioned organic solvent to prepare a solution for forming a medium-to-medium refractive index layer.

[0166] [Formation of the intermediate refractive index layer]

[0167] The above-mentioned medium refractive index layer forming solution is applied to the medium and low refractive index layer, dried, and then heated to solidify it to form the medium refractive index layer.

[0168] The coating method, drying conditions, and heating conditions are based on the method for forming medium- and low-refractive-index layers. Furthermore, similarly, from the viewpoint of productivity and the properties of the resulting antireflective film, the thermosetting process using heat is preferably performed in one step after coating and drying the four layers constituting the antireflective film, or further after coating and drying the protective layer.

[0169] <High Refractive Index Layer>

[0170] The refractive index layer is stacked on top of the aforementioned intermediate refractive index layer (viewing side) and has a higher refractive index than the intermediate refractive index layer.

[0171] The high refractive index layer has a refractive index of 1.75–1.87 and a layer thickness of 30–50 nm. Preferably, the refractive index is 1.77–1.85 and the layer thickness is 35–45 nm.

[0172] Since the high refractive index layer needs to be strengthened by chemical treatment after the formation of the antireflective film and the protective layer, it is preferable to prepare a solution containing the following components, cover the solution, and dry and heat it to form the high refractive index layer.

[0173] Relative to (B) 100 parts by mass of the binder component formed from the alkoxysilane compound or its hydrolysate (hereinafter referred to as "alkoxysilane compound, etc.") shown in formula (1),

[0174] R n -Si(OR 1 ) 4-n (1)

[0175] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2)

[0176] (A) 1-15 parts by weight of aluminum hydrate, and

[0177] (E) 40-130 parts by weight of metal oxide particles

[0178] In order for the anti-reflective glass of the present invention to exhibit alkali resistance, (A) aluminum hydrate needs to be present in the high refractive index layer.

[0179] [Alkoxysilane compounds or their hydrolysates]

[0180] The compound represented by formula (1) above is as described in the section on low and medium refractive index layers. Alkoxysilane compounds, etc., used in the formation of low and medium refractive index layers can be used in the same way for the same purpose.

[0181] [Aluminum salt hydrate]

[0182] As a component that contributes to the alkali resistance of the present invention, the aluminum hydrate is preferably present simultaneously in the low refractive index layer, the protective layer, and the high refractive index layer. The aluminum hydrate used in the formation of the medium and low refractive index layers can also be used as the aluminum hydrate.

[0183] In the high refractive index layer, the content of aluminum hydrate is 1 to 15 parts by mass relative to 100 parts by mass of the aforementioned alkoxysilane compound, etc. A content below 1 part by mass is ineffective. If it exceeds 15 parts by mass, it is difficult to form a layer due to easy reaction with moisture in the air during coating, and therefore is not preferred.

[0184] [Metal oxide particles]

[0185] In the high refractive index layer, metal oxide particles are mixed in order to control the refractive index as specified above.

[0186] The same metal particles used in the formation of the intermediate refractive index layer are used as metal oxide particles.

[0187] The content of metal oxide particles in the high refractive index layer composition is 40 to 130 parts by mass relative to 100 parts by mass of alkoxysilane compounds, etc., and is preferably appropriately selected from the range of 0 to 40 parts by mass of zirconium oxide particles and 40 to 90 parts by mass of titanium oxide particles, taking into account the refractive index change due to thermal history, etc., to meet the aforementioned specified refractive index. In particular, titanium oxide particles are preferred to achieve a high refractive index.

[0188] [Solution for forming high refractive index layers]

[0189] The aforementioned components constituting the high refractive index layer, along with any other components such as an acidic aqueous solution as needed, are dissolved in the aforementioned organic solvent to prepare a solution for forming the high refractive index layer.

[0190] [Formation of a high-refractive-index layer]

[0191] The high refractive index layer is formed by coating the medium refractive index layer with the solution and drying it, followed by heating to solidify it.

[0192] The coating method, drying conditions, and heating conditions are based on the method for forming medium- and low-refractive-index layers. Furthermore, similarly, from the viewpoint of productivity and the properties of the resulting antireflective film, the thermosetting process using heat is preferably performed in one step after coating and drying the four layers constituting the antireflective film, or further after coating and drying the protective layer.

[0193] <Low Refractive Index Layer>

[0194] This is the refractive index layer located on the outermost (viewing side) of the antireflective coating, and it is the layer that best contributes to the antireflective performance.

[0195] The low-refractive-index layer has a refractive index of 1.27–1.35 and a layer thickness of 70–75 nm. Preferably, the refractive index is 1.28–1.32 and the layer thickness is 71–74 nm.

[0196] Since the low refractive index layer needs to be strengthened by chemical treatment after the formation of the antireflective film and the protective layer, it is preferable to prepare a solution containing the following components, cover the solution, and dry and heat it to form the low refractive index layer.

[0197] Relative to (B) 100 parts by mass of the binder component formed from the alkoxysilane compound or its hydrolysate (hereinafter referred to as "alkoxysilane compound, etc.") shown in formula (1),

[0198] R n -Si(OR 1 ) 4-n (1)

[0199] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2)

[0200] (A) 3-25 parts by weight of aluminum hydrate

[0201] (C) 1-20 parts by weight of metal chelate compound, and

[0202] (D) 25-90 parts by weight of silica particles

[0203] In order for the anti-reflective glass of the present invention to exhibit alkali resistance, (A) aluminum hydrate needs to be present in the low refractive index layer.

[0204] [Alkoxysilane compounds or their hydrolysates]

[0205] The compound represented by formula (1) above is as described in the section on low and medium refractive index layers. Alkoxysilane compounds, etc., used in the formation of low and medium refractive index layers can be used in the same way for the same purpose.

[0206] [Aluminum salt hydrate]

[0207] As a component that contributes to the alkali resistance of the present invention, the aluminum hydrate is preferably present simultaneously in the high refractive index layer, the protective layer, and the low refractive index layer. The aluminum hydrate used in the formation of the medium and low refractive index layers can also be used as the aluminum hydrate.

[0208] In the low-refractive-index layer, the content of aluminum hydrate is 3 to 25 parts by mass relative to 100 parts by mass of the aforementioned alkoxysilane compound, etc. A content below 3 parts by mass is not effective. If it exceeds 25 parts by mass, it is not preferred due to the reduced bonding strength of the aforementioned alkoxysilane compound, etc., and the decreased hardness of the low-refractive-index layer.

[0209] [Metal chelate compounds]

[0210] Metal chelates used in the formation of low to medium refractive index layers can be used without any restrictions for the same purpose.

[0211] The metal chelate compound is used in a ratio of 1 to 20 parts by mass, preferably 3 to 18 parts by mass, relative to 100 parts by mass of the (B) alkoxysilane compound. If the ratio exceeds 20 parts by mass, the metal chelate compound tends to precipitate in the low refractive index layer, which may cause poor appearance. If the ratio is less than 1 part by mass, the strength and hardness of the low refractive index layer tend to decrease.

[0212] [Silica particles]

[0213] Silica particles used in the formation of medium and low refractive index layers can be used without any restrictions for the same purpose.

[0214] The silica particles are 25 to 90 parts by mass relative to 100 parts by mass of (B) alkoxysilane compounds, and are preferably selected appropriately from the range of 0 to 30 parts by mass of solid silica particles and 25 to 60 parts by mass of hollow silica particles, taking into account the refractive index changes due to thermal history, so as to satisfy the aforementioned refractive index requirements for a low-refractive-index layer. In particular, the inclusion of hollow silica particles is preferred from the viewpoint that a low refractive index can be achieved to realize high anti-reflective performance.

[0215] [Solution for forming low refractive index layers]

[0216] The aforementioned components constituting the low refractive index layer, along with any other components such as an acidic aqueous solution as needed, are dissolved in the aforementioned organic solvent to prepare a solution for forming the low refractive index layer.

[0217] [Formation of a low-refractive-index layer]

[0218] The solution for forming the low refractive index layer is applied onto the high refractive index layer, dried, and then heated to cure it to form the low refractive index layer.

[0219] The coating method, drying conditions, and heating conditions are based on the method for forming medium- and low-refractive-index layers. Furthermore, similarly, from the viewpoint of productivity and the properties of the resulting antireflective film, the thermosetting process using heat is preferably performed in one step after coating and drying the four layers constituting the antireflective film, or further after coating and drying the protective layer.

[0220] <Protective Layer>

[0221] A protective layer is provided on the antireflective film (viewing side) to prevent damage to the antireflective film due to external impacts such as scratches, and further to prevent damage caused by ion collisions during chemical strengthening.

[0222] The refractive index of the protective layer is 1.43–1.48, and the layer thickness is 20–30 nm. Preferably, the refractive index is 1.44–1.46, and the layer thickness is 20–25 nm.

[0223] Since the protective layer needs to be glass-strengthened by chemical treatment after the anti-reflective film and the protective layer are formed, it is preferable to prepare a solution containing the following components, cover the solution, and dry and heat it to form the protective layer.

[0224] Relative to (B) 100 parts by mass of the binder component formed from the alkoxysilane compound or its hydrolysate (hereinafter referred to as "alkoxysilane compound, etc.") shown in formula (1),

[0225] R n -Si(OR 1 ) 4-n (1)

[0226] (In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group, R 1 (where n is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2.)

[0227] (A) 3-25 parts by weight of aluminum hydrate, and

[0228] (C) 1-20 parts by weight of metal chelate compound

[0229] In order for the anti-reflective glass of the present invention to exhibit alkali resistance, (A) aluminum hydrate needs to be present in the protective layer.

[0230] [Alkoxysilane compounds or their hydrolysates]

[0231] The compound represented by formula (1) above is as described in the section on low and medium refractive index layers. Alkoxysilane compounds, etc., used in the formation of low and medium refractive index layers can be used in the same way for the same purpose.

[0232] [Aluminum salt hydrate]

[0233] As a component that contributes to the alkali resistance performance in this invention, the aluminum hydrate needs to be present simultaneously in the low refractive index layer, the high refractive index layer, and the protective layer. The aluminum hydrate used in the formation of the medium and low refractive index layers can be used as the aluminum hydrate.

[0234] In the protective layer, the content of aluminum hydrate is 3 to 25 parts by mass relative to 100 parts by mass of the aforementioned alkoxysilane compound, etc. A content below 3 parts by mass is not effective. If it exceeds 25 parts by mass, it is not preferred due to the reduced bonding strength of the alkoxysilane compound, etc., and the decreased hardness of the protective layer.

[0235] [Metal chelate compounds]

[0236] Metal chelates used in the formation of low to medium refractive index layers can be used without any restrictions for the same purpose.

[0237] The metal chelate compound is used in a ratio of 1 to 20 parts by mass, preferably 3 to 18 parts by mass, relative to 100 parts by mass of the (B) alkoxysilane compound. If the ratio exceeds 20 parts by mass, the metal chelate compound tends to precipitate in the protective layer, potentially causing poor appearance. If the ratio is less than 1 part by mass, the strength and hardness of the protective layer decrease, and there is a tendency for insufficient chemical strengthening treatment of the glass substrate.

[0238] [Protective layer forming solution]

[0239] The aforementioned components constituting the protective layer, along with any other components such as an acidic aqueous solution as needed, are dissolved in the aforementioned organic solvent to prepare a solution for forming the protective layer.

[0240] [Formation of the protective layer]

[0241] The above-mentioned protective layer forming solution is applied to the low refractive index layer, dried, and then heated to cure it to form a protective layer.

[0242] The coating method, drying conditions, and heating conditions are based on the method for forming medium- and low-refractive-index layers. Furthermore, similarly, from the viewpoint of productivity and the properties of the resulting antireflective film, the thermosetting process using heat is preferably performed in one step, consisting of coating and drying the four layers constituting the antireflective film, followed by coating and drying the protective layer.

[0243] <Glass strengthening using chemical treatment>

[0244] The anti-reflective glass of the present invention is strengthened by chemical treatment. By selecting the components of each of the four layers constituting the anti-reflective film, as described above, and simultaneously utilizing the internal space of the particles and the interparticle spaces for ion exchange, the glass is strengthened.

[0245] As a chemical treatment method, conventionally known methods are employed. A representative example is the process of contacting unstrengthened antireflective glass with a molten metal salt such as potassium nitrate at 390°C–450°C for 3–16 hours, thereby replacing sodium ions with potassium ions with larger ionic radii, thus producing high-strength strengthened glass.

[0246] <Alkali Cleaning>

[0247] In the preceding or following steps of the glass strengthening process, alkaline cleaning is performed for the purpose of removing organic / inorganic substances adhering to the glass surface, preventing the glass from becoming frosted and losing its transparency (to prevent burns), and for other reasons.

[0248] Regarding alkaline cleaning, since alkaline cleaning solutions with a pH of around 12-13, obtained by dissolving strong alkaline compounds such as sodium hydroxide and potassium hydroxide, as well as surfactants, in alcohol-based solvents and water, are commercially available, the cleaning solution should be appropriately diluted with water or other solvents according to the purpose and conditions of alkaline cleaning.

[0249] Alkaline cleaning is usually carried out at room temperature to 55°C for about 0.1 to 0.5 hours, followed by cleaning with water and organic solvents to remove the alkaline cleaning solution.

[0250] Example

[0251] The present invention will now be described in detail with reference to specific embodiments, but the present invention is not limited to these embodiments in any way. Furthermore, the combinations of features described in the embodiments are not necessarily all necessary for the solution of the present invention.

[0252] The various ingredients and abbreviations used in the following examples and comparative examples, as well as the test methods, are as follows.

[0253] (A) Aluminum salt hydrate

[0254] AlCl3·6H2O: Aluminum chloride hexahydrate

[0255] Al(NO3)3·9H2O: Aluminum nitrate nonhydrate

[0256] (B) Alkoxysilane compounds, etc.

[0257] TEOS: Tetraethoxysilane

[0258] (C) Metal chelate compounds

[0259] AlTA: Tri(acetylacetone)aluminum

[0260] (D) Silica particles

[0261] Hollow silica particles

[0262] Average particle size: 40 nm, refractive index: 1.25, solid content: 20 wt%.

[0263] Dispersing solvent IPA

[0264] solid silica particles

[0265] Average particle size: 7 nm, refractive index: 1.45, solid content: 20 wt%.

[0266] Dispersing solvent: IPA

[0267] (E) Metal oxide particles

[0268] Zirconia particles

[0269] Average particle size: 61.9 nm, refractive index: 2.40, solid content: 30 wt%.

[0270] Dispersing solvent: methanol

[0271] Titanium oxide particles:

[0272] Average particle size: 108.8 nm, refractive index: 2.71, solid content: 15% by weight.

[0273] Dispersing solvent: methanol

[0274] (Organic solvents)

[0275] IPA: Isopropyl alcohol

[0276] Eta Cohol: A mixture of ethanol and isopropanol

[0277] NPA: n-Propanol

[0278] SBAC: sec-butyl acetate

[0279] (Hydrolysis catalyst)

[0280] HCl: 0.05N hydrochloric acid

[0281] (Glass substrate)

[0282] Sodium-calcium silicate glass (50mm×88mm×1.1mm)

[0283] (Other metal salt hydrates)

[0284] Ni(NO3)2·6H2O: Nickel nitrate hexahydrate

[0285] Co(NO3)2·6H2O: Cobalt nitrate hexahydrate

[0286] [Refractive index of each refractive index layer]

[0287] The solution for forming each refractive index layer was coated onto a glass substrate at a thickness of 100 nm and allowed to cure, forming each refractive index layer or protective layer. The reflectance of each layer was measured using a "Spectrophotometer V-650" manufactured by Nippon Spectrophotometer Co., Ltd., and the refractive index was calculated.

[0288] [Average light reflectance of both sides]

[0289] The average light reflectance of both sides (hereinafter also referred to as average light reflectance) is determined by the following method.

[0290] Measurements were performed using a V-650 UV-Vis spectrophotometer manufactured by Nippon Spectrophotometer Co., Ltd., in the range of 380 nm to 780 nm. The results were calculated based on JIS Z8722 multiplied by a weighting factor. The object of measurement was anti-reflective glass with anti-reflective films and protective layers formed on both sides of a glass substrate. It should be noted that these measured values ​​are for anti-reflective glass before glass strengthening, but it was confirmed that these values ​​remain almost unchanged after glass strengthening.

[0291] Average light transmittance

[0292] The average light transmittance was measured as follows. Measurements were performed using a V-650 UV-Vis spectrophotometer manufactured by Nippon Spectrophotometer Co., Ltd., at a wavelength of 380 nm to 780 nm. The values ​​were calculated based on JIS Z8722 multiplied by a weighting factor. It should be noted that these measured values ​​are for anti-reflective glass before glass strengthening, but it was confirmed that this value remained almost unchanged after glass strengthening.

[0293] [Alkali resistance of antireflective film]

[0294] To investigate the alkali resistance of antireflective films based on alkali cleaning, the color change of antireflective glass panels before and after alkali cleaning was observed visually and evaluated according to the following criteria. The basic antireflective glass (uncured) was colorless and transparent. Evaluation was conducted on strengthened antireflective glass. It should be noted that "before strengthening" refers to the alkali resistance after alkali cleaning before glass strengthening, and "after strengthening" refers to the alkali resistance after alkali cleaning after glass strengthening.

[0295] The marks “◎” and “〇” indicate that the antireflective film has not been optically altered due to alkaline cleaning. “×” indicates that the antireflective film has clearly peeled off.

[0296] ◎: No change

[0297] ○: Slight color change (lighter color)

[0298] △: Color change (darker color)

[0299] ×: Membrane peeling

[0300] [Glass strength; compressive stress measurement]

[0301] The surface stress CS (MPa) and stress layer depth DOL (μm) of chemically strengthened glass were measured using the "FSM-6000LE" manufactured by Orihara Seisakusho Co., Ltd. Higher CS and DOL values ​​indicate greater strengthening. A DOL value of 10 μm or higher is sufficient for functioning as strengthened glass.

[0302] [Preparation of solutions for forming medium- and low-refractive-index layers]

[0303] Mix the components shown in Tables 1 and 2 at the same mixing amounts shown in the tables to prepare solutions for forming medium and low refractive index layers (ML-1 to ML-9).

[0304] ML-6 is a solution that does not contain (A) aluminum salt hydrates, while ML-8 and 9 are solutions that contain metal salt hydrates other than aluminum.

[0305] [Table 1]

[0306] Solution for forming medium and low refractive index layers (1)

[0307]

[0308] [Table 2]

[0309] Solution for forming medium and low refractive index layers (2)

[0310]

[0311] [Preparation of solutions for forming medium refractive index layers]

[0312] Mix the components shown in Tables 3 and 4 at the same mixing amounts shown in the tables to prepare solutions for forming intermediate refractive index layers (M-1 to M-7).

[0313] M-4 is a solution that does not contain (A) aluminum salt hydrates, while M-6 and 7 are solutions that contain metal salt hydrates other than aluminum.

[0314] [Table 3]

[0315] Solution for forming intermediate refractive index layer (1)

[0316]

[0317] [Table 4]

[0318] Solution for forming a medium refractive index layer (2)

[0319]

[0320] [Preparation of solutions for forming high refractive index layers]

[0321] Mix the components shown in Tables 5 and 6 at the same mixing amounts shown in the tables to prepare solutions for forming high refractive index layers (H-1 to H-9).

[0322] H-6 is a solution that does not contain (A) aluminum salt hydrates, while H-8 and 9 are solutions that contain metal salt hydrates other than aluminum.

[0323] [Table 5]

[0324] Solution for forming high refractive index layers (1)

[0325]

[0326] [Table 6]

[0327] Solution for forming high refractive index layer (2)

[0328]

[0329] [Preparation of solutions for forming low-refractive-index layers]

[0330] Mix the components shown in Tables 7 and 8 at the same mixing amounts shown in the tables to prepare solutions for forming low refractive index layers (L-1 to L-9).

[0331] L-6 is a solution that does not contain (A) aluminum salt hydrates, while L-8 and 9 are solutions that contain metal salt hydrates other than aluminum.

[0332] [Table 7]

[0333] Solution for forming low refractive index layers (1)

[0334]

[0335] [Table 8]

[0336] Solution for forming low refractive index layer (2)

[0337]

[0338] [Preparation of solution for protective layer formation]

[0339] Mix the components shown in Table 9 at the same mixing amounts shown in the table to prepare a protective layer forming solution (Co-1 to Co-5).

[0340] Co-2 is a solution that does not contain (A) aluminum salt hydrates, while Co-4 and 5 are solutions that contain metal salt hydrates other than aluminum.

[0341] [Table 9]

[0342] Solution for forming protective layer

[0343]

[0344] Example 1

[0345] The aforementioned aluminosilicate glass (glass substrate) was immersed in a solution for forming a low-to-medium refractive index layer (ML-6) and then dried at 100°C for 15 minutes to form an uncured low-to-medium refractive index layer with a thickness of 197 nm on the glass substrate. It is assumed that the low-to-medium refractive index layer is not fully cured under the above drying conditions, and the same applies to the subsequent layers. It should be noted that the layer thickness is adjusted by the lifting rate from the immersed low-to-medium refractive index layer forming solution. The same applies to the subsequent layers.

[0346] Next, the glass substrate is immersed in a medium refractive index layer forming solution (M-4) and dried at 100°C for 15 minutes to form an uncured medium refractive index layer with a thickness of 109 nm on the uncured low refractive index layer.

[0347] Next, the glass substrate is immersed in a high refractive index layer forming solution (H-1) and dried at 100°C for 15 minutes to form an uncured high refractive index layer with a thickness of 36 nm on the uncured medium refractive index layer.

[0348] Next, the glass substrate is immersed in a low refractive index layer forming solution (L-1) and dried at 100°C for 15 minutes to form an uncured low refractive index layer with a thickness of 75 nm on the uncured high refractive index layer.

[0349] Next, the glass substrate is immersed in a protective layer forming solution (Co-1) and dried at 100°C for 15 minutes to form an uncured protective layer with a thickness of 25 nm on the uncured low refractive index layer.

[0350] The glass substrate obtained by laminating the uncured antireflective film and the protective layer was heat-cured at 500°C for 30 minutes to produce the antireflective glass of the present invention. The average light reflectance and average light transmittance of both sides of the obtained antireflective glass were measured according to the aforementioned method, and are shown in Table 10 along with the layer thickness and refractive index of each layer.

[0351] The following two methods are then used for alkaline cleaning and glass strengthening of the anti-reflective glass.

[0352] On one hand, for the aforementioned antireflective glass, it is first subjected to alkaline cleaning by immersing the glass in a diluted solution obtained by diluting "SEMICLEAN MG; pH=12.4" manufactured by Yokohama Yushi Kogyo Co., Ltd. with water at 5 wt%, under ultrasonic conditions at 40°C for 10 minutes. The cleaning solution is then rinsed off with warm water and IPA. Next, it undergoes chemical strengthening treatment by immersing the glass in molten potassium nitrate at 410°C for 3 hours, thus producing antireflective strengthened glass. On the other hand, antireflective strengthened glass is produced by first performing chemical strengthening treatment under the same conditions, and then undergoing alkaline cleaning under the same conditions.

[0353] The glass strength and alkali resistance of the antireflective coating based on alkali cleaning of the two types of antireflective tempered glass were determined according to the aforementioned method. The results are shown in Table 10.

[0354] Examples 2-9

[0355] Using the solutions for forming each refractive index layer and the solution for forming the protective layer as shown in Table 10, and otherwise the same as in Example 1, two types of anti-reflective strengthened glass were produced.

[0356] Table 10 shows the average light reflectance and average light transmittance of both sides of the anti-reflective tempered glass, the layer thickness and refractive index of each layer, and consequently the glass strength and alkali resistance of the anti-reflective film.

[0357] Antireflective tempered glass containing aluminum chloride hexahydrate in all layers of the antireflective film and protective layer (Examples 2-6 and 8) exhibits sufficient glass strength and excellent alkali resistance. In the cases where aluminum chloride hexahydrate is absent in the low-to-medium refractive index layer and the medium refractive index layer (Example 1), where aluminum chloride hexahydrate is absent in the medium refractive index layer (Example 7), and where aluminum nitrate nonahydrate is present in all layers of the antireflective film and protective layer (Example 9), the color changes slightly, but sufficient alkali resistance is still observed.

[0358] [Table 10]

[0359]

[0360] Comparative Examples 1-10

[0361] Two types of anti-reflective strengthened glass were produced by using the solutions for forming each refractive index layer and the solution for forming the protective layer in the combinations shown in Table 11, except that the process was the same as in Example 1.

[0362] Table 11 shows the average light reflectance and average light transmittance of both sides of the anti-reflective glass, the layer thickness and refractive index of each layer, and consequently the glass strength of the anti-reflective tempered glass and the alkali resistance of the anti-reflective film.

[0363] Comparative Example 1 shows the absence of aluminum hydrates in all layers of the antireflective film and protective layer, exhibiting extremely poor alkali resistance. Comparative Example 2 shows the absence of aluminum hydrates in the high-refractive-index layer, medium-refractive-index layer, and medium-low-refractive-index layer, also exhibiting extremely poor alkali resistance.

[0364] Comparative Example 3, where aluminum hydrates are absent in the low-refractive-index layer, medium-refractive-index layer, and medium-low-refractive-index layer, exhibits poor alkali resistance. Comparative Example 4, where aluminum hydrates are absent in the protective layer, medium-refractive-index layer, and medium-low-refractive-index layer, also exhibits poor alkali resistance.

[0365] Comparative Examples 5 and 6 represent cases where the thickness of the refractive index layer does not meet the scope of this invention. They exhibit good alkali resistance, but poor optical properties in terms of average light reflectance and average light transmittance.

[0366] Comparative Examples 7 and 8 represent cases where the refractive index of the refractive index layer does not meet the scope of this invention. They exhibit good alkali resistance but poor optical properties in terms of average light reflectance and average light transmittance.

[0367] Comparative Examples 9 and 10 show cases where metal salt hydrates other than aluminum salt hydrates are used in all layers of the antireflective film and protective layer, resulting in extremely poor alkali resistance.

[0368] [Table 11]

[0369]

Claims

1. An anti-reflective glass, characterized in that, It consists of a glass substrate, an anti-reflective film, and a protective layer, in sequence. The anti-reflective film extends from the glass substrate side. Medium-low refractive index layer with a refractive index of 1.36~1.45 and a thickness of 150~210nm; A medium refractive index layer with a refractive index of 1.56~1.79 and a thickness of 90~140nm. A high refractive index layer with a refractive index of 1.75~1.87 and a thickness of 30~50nm. A low-refractive-index layer with a refractive index of 1.27~1.35 and a thickness of 70~75nm. The layers are arranged in a specific order, with the high-refractive-index layer having a higher refractive index than the intermediate-refractive-index layer. The protective layer has a refractive index of 1.43~1.48 and a thickness of 20~30 nm. The high-refractive-index layer, low-refractive-index layer, and protective layer contain (A) aluminum hydrate. The average light reflectance of both surfaces in the wavelength range of 380~780nm is less than 0.6%, and the average light transmittance in the wavelength range of 380~780nm is more than 98%. Furthermore, the low-to-medium refractive index layer and the medium refractive index layer contain (A) aluminum hydrate. The high refractive index layer is formed from a cured high refractive index layer composition, wherein the high refractive index layer composition contains 1-15 parts by mass of (A) aluminum hydrate and 40-130 parts by mass of (E) metal oxide particles relative to 100 parts by mass of (B) a binder component formed from an alkoxysilane compound or its hydrolysate as shown in formula (1). R n -Si(OR 1 ) 4-n (1) In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group. 1 It is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2.

2. The anti-reflective glass according to claim 1, characterized in that, The protective layer is formed from a cured protective layer composition, wherein the protective layer composition contains, relative to 100 parts by weight of (B) an adhesive component formed from an alkoxysilane compound or its hydrolysate as shown in formula (1), 3-25 parts by weight of (A) an aluminum hydrate and 1-20 parts by weight of (C) a metal chelate compound. R n -Si(OR 1 ) 4-n (1) In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group. 1 It is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2.

3. The anti-reflective glass according to claim 1, characterized in that, The low refractive index layer is formed from a cured low refractive index layer composition, wherein the low refractive index layer composition contains, relative to 100 parts by mass of (B) an adhesive component formed from an alkoxysilane compound or its hydrolysate as shown in formula (1), 3-25 parts by mass of (A) aluminum hydrate, 1-20 parts by mass of (C) a metal chelate compound, and 25-90 parts by mass of (D) silica particles. R n -Si(OR 1 ) 4-n (1) In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group. 1 It is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2.

4. The anti-reflective glass according to claim 1, characterized in that, The intermediate refractive index layer is formed from a cured intermediate refractive index layer composition, wherein the intermediate refractive index layer composition contains 1-15 parts by mass of (A) aluminum hydrate and 40-130 parts by mass of (E) metal oxide particles relative to 100 parts by mass of (B) a binder component formed from an alkoxysilane compound or its hydrolysate as shown in formula (1). R n -Si(OR 1 ) 4-n (1) In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group. 1 It is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2.

5. The anti-reflective glass according to claim 1, characterized in that, The low-to-medium refractive index layer is formed from a cured product of the low-to-medium refractive index layer composition. The low-to-medium refractive index layer composition contains, relative to 100 parts by mass of (B) the binder component formed from the alkoxysilane compound or its hydrolysate as shown in formula (1), 3-25 parts by mass of (A) aluminum hydrate, 1-20 parts by mass of (C) metal chelate compound, and 25-90 parts by mass of (D) silica particles. R n -Si(OR 1 ) 4-n (1) In the formula, R is an alkyl, alkenyl, or alkoxyalkyl group. 1 It is an alkyl, alkoxyalkyl, acyloxy, or halogen atom, and n is an integer of 1 or 2.

6. The anti-reflective glass according to claim 1, characterized in that, The glass substrate is alkali aluminosilicate glass.

7. The anti-reflective glass according to claim 1, characterized in that, The anti-reflective glass is an alkali-resistant chemically strengthened anti-reflective glass.

8. A method for manufacturing anti-reflective tempered glass, characterized in that, It includes a step of chemically strengthening the antireflective glass of claim 1 in an ion-exchange metal salt molten solution; and a step of alkaline cleaning before or after the chemical strengthening step.

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