Anti-reflective glass

Abstract

To provide antireflection glass used in production of reinforced antireflection glass, which is suitable in bending and has a high degree of antireflection ability.SOLUTION: An antireflection glass comprising a glass substrate, an antireflection film, and a protective layer in this order, wherein the antireflection film has, in the order from the glass substrate side, a middle refractive index layer of a refractive index of 1.67 to 1.87 and a layer thickness of 35 to 120 nm, a high refractive index layer of the refractive index of 1.90 to 2.05 and a layer thickness of 30 to 115 nm, and a low refractive index layer of a refractive index of 1.34 to 1.45 and a layer thickness of 45 to 115 nm, and the protective layer has the refractive index of 1.42 to 1.48 and a layer thickness of 5 to 50 nm, the high refractive index layer is made of a cured material of a curable composition containing a metal alkoxide oligomer, and has an average luminous reflectance of 0.6% or less on both sides, and a protective layer and an antireflection film when bent with a glass surface elongation rate of 5% or less, anti-reflection glass is characterized by no cracks.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to anti-reflection glass imparted with a high degree of anti-reflection performance, and is suitably used for producing anti-reflection tempered glass that is subjected to bending processing. [Background technology]

[0002] Tempered glass, which has increased glass strength, is widely used in applications such as window glass for automobiles and houses, as well as for front protective panels for capacitive touch panels and displays for various mobile devices such as digital cameras and mobile phones. In recent years, there has been a growing demand for automotive meter panels that are integrated with a monitor known as a Center Information Display (CID), which offers stylish design and a luxurious feel, and specifications that connect the meter and CID with a curved surface are beginning to be required. Such glass panels must necessarily be made of tempered glass, as ordinary glass is at risk of breakage in an accident.

[0003] The above-mentioned automotive meter panels are required to have high anti-reflection properties, similar to protective panels and various displays. To impart anti-reflection properties, an anti-reflection film containing a low refractive index layer may be formed on the glass surface. In order to improve the antireflection performance of antireflection films, high-performance multilayer antireflection films have been developed, such as those that are not made up of a single low-refractive index layer but are made up of two layers with a high-refractive index layer between the low-refractive index layer and the glass substrate, or even those that are made up of three layers with a medium-refractive index layer between the high-refractive index layer and the glass substrate (Patent Document 1). However, in the case of the above-mentioned tempered glass having a high-performance anti-reflection function, the following problems arise during bending. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Application No. 2021-135870 (WO2023 / 026670) Summary of the Invention [Problem to be solved by the invention]

[0005] In the past, the high-refractive-index layer and the medium-refractive-index layer have contained metal oxide particles, such as zirconium oxide particles or titanium oxide particles, which have a higher refractive index than silica particles, in order to achieve a predetermined refractive index. As a result, in these conventional products, when anti-reflection glass on which an anti-reflection film is laminated is heated and bent before being tempered, cracks occur in the anti-reflection film, resulting in the production of defective products. As a result of thorough analysis of the occurrence of cracks during bending, the inventors have found that cracks tend to occur mainly in high refractive index layers containing a relatively large amount of metal oxide particles, and that by using a metal alkoxide oligomer instead of these metal oxide particles, it is possible to prevent the occurrence of cracks while maintaining a high refractive index, which led to the invention of the present invention. [Means for solving the problem]

[0006] That is, the present invention provides an anti-reflection glass having a glass substrate, an anti-reflection film, and a protective layer in this order, The anti-reflection film is formed by, in order from the glass substrate side, A medium refractive index layer having a refractive index of 1.67 to 1.87 and a layer thickness of 35 to 120 nm; a high refractive index layer having a refractive index of 1.90 to 2.05 and a layer thickness of 30 to 115 nm; A low refractive index layer with a refractive index of 1.34 to 1.45 and a layer thickness of 45 to 120 nm. Equipped with The protective layer has a refractive index of 1.42 to 1.48 and a thickness of 5 to 50 nm, and the high refractive index layer is made of a cured product of a curable composition containing a metal alkoxide oligomer (the metal is a titanium atom or a zirconium atom), and the average luminous reflectance on both surfaces is 0.6% or less, and no cracks occur in the protective layer or the antireflection film when the glass surface is bent with an elongation of 5% or less.

[0007] In the above anti-reflective glass invention, 1) The medium refractive index layer is made of a cured product of a curable composition containing 25 to 70 parts by mass of metal oxide particles relative to 100 parts by mass of a binder component made of an alkoxysilane compound represented by the following formula (1) or a partial hydrolyzate thereof: R n -Si(OR1) 4-n (1) (In the formula, R is an alkyl group, an alkenyl group, or an alkoxyalkyl group, R1 is an alkyl group, an alkoxyalkyl group, or a halogen atom, and n is an integer of 0, 1, or 2.) 2) The low refractive index layer is made of a cured product of a curable composition containing 1 to 15 parts by mass of hollow silica particles and 1 to 10 parts by mass of aluminum salt hydrate, relative to 100 parts by mass of a binder component consisting of an alkoxysilane compound represented by formula (1) or a partial hydrolyzate thereof; 3) The protective layer is made of a cured product of a curable composition containing 100 parts by mass of a binder component consisting of an alkoxysilane compound represented by formula (1) or a partial hydrolyzate thereof, 1 to 25 parts by mass of a metal chelate compound, and 1 to 20 parts by mass of an aluminum salt hydrate; 4) In an accelerated weather resistance test at a temperature of 63°C, humidity of 50% RH, and a test time of 2000 hours, there is no peeling of the anti-reflection film or protective layer. 5) Anti-reflective glass used for chemical strengthening is preferred.

[0008] The present invention also relates to a method for producing tempered anti-reflective glass, which comprises heating and bending the above-mentioned anti-reflective glass, and then chemically tempering the glass in a molten solution of a metal salt for ion exchange. [Effects of the Invention]

[0009] The anti-reflective glass provided by the present invention can be bent and is suitable for use in the production of anti-reflective tempered glass having a high level of anti-reflective performance. Such anti-reflective tempered glass products are suitable for use in products with thin glass substrates, such as front protective panels for capacitive touch panels, displays for various mobile devices such as digital cameras and mobile phones, as well as large, luxurious, and heavy integrated automotive meter panels. In addition to its bending properties, it also has excellent weather resistance, making it suitable for use in curved outdoor products such as spherical security camera exterior covers. Furthermore, even when anti-reflective glass is subjected to alkaline cleaning, the anti-reflective film is less likely to deteriorate, providing the advantage of excellent alkali resistance. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Anti-reflective glass> The anti-reflection glass of the present invention comprises a glass substrate, an anti-reflection film, and a protective layer in this order. The anti-reflection film is formed from the glass substrate side as follows: A medium refractive index layer having a refractive index of 1.67 to 1.87 and a layer thickness of 35 to 120 nm; a high refractive index layer having a refractive index of 1.90 to 2.05 and a layer thickness of 30 to 115 nm; It is composed of a low refractive index layer having a refractive index of 1.34 to 1.45 and a layer thickness of 45 to 120 nm. The protective layer has a refractive index of 1.42 to 1.48 and a thickness of 5 to 50 nm. The anti-reflection glass has the optical property of having an average luminous reflectance of 0.6% or less on both sides. Furthermore, the anti-reflection glass has the characteristic that no cracks occur in the protective layer and the anti-reflection film when the glass surface is bent at an elongation rate of 5% or less.

[0011] The bending test is a test method in which a glass test piece is placed on a bending mold and subjected to a single cycle of heating in an electric furnace, heating for bending, and slow cooling. This applies to bending under its own weight or hot bending using a press. Bending with an elongation of 5% or less on the glass surface refers to hot bending in which the elongation of the outermost surface of the glass is 5% or less using this test method. "No cracks" means that, when the surface of the bent portion is observed with a laser microscope, no crack-like patterns are found in the direction perpendicular to the elongation direction. The anti-reflective glass of the present invention is also highly weather resistant, and no peeling between the glass substrate and the anti-reflective film, interlayer delamination between the refractive index layers, or peeling between the anti-reflective film and the protective layer is observed.

[0012] The greatest feature of the present invention is that the above-mentioned bending properties are achieved by using a metal alkoxide oligomer (wherein the metal is a titanium atom or a zirconium atom) as a refractive index adjuster in the high refractive index layer. Conventionally, when metal oxide particles are used, interfacial peeling tends to occur on the particle surface during bending, resulting in cracks. It is believed that the use of the metal alkoxide oligomer prevents this. Furthermore, since the content of hollow silica particles in the low refractive index layer is reduced, it is believed that the occurrence of cracks from the particle surface is also reduced.

[0013] In addition to the above-mentioned optical properties and bending properties, the anti-reflection glass of the present invention also has excellent weather resistance, with no peeling between the glass substrate and the anti-reflection film, no interlayer delamination between the refractive index layers, and no peeling between the anti-reflection film and the protective layer. Specifically, in an accelerated weathering test at a temperature of 63°C, a humidity of 50% RH (relative humidity), and a test time of 2000 hours, no peeling of the anti-reflection film or the protective layer was observed. The improved weather resistance is presumably due to the reduced content of hollow silica particles contained in the low-refractive-index layer, which was achieved by setting the refractive index higher. Because hollow silica particles have internal cavities, ultraviolet light penetrates these cavities, causing deterioration of each layer of the anti-reflection coating. The reduced content of hollow silica particles reduces the amount of ultraviolet light passing through the cavities, and the binder component increases by the same amount, increasing the crosslink density of the layer and further reducing the transmission of ultraviolet light. Furthermore, as mentioned above, the absence of metal oxide particles in the high-refractive-index layer is believed to prevent ultraviolet light from passing through the gaps between the particles, further improving weather resistance.

[0014] <Glass substrate> There are no particular limitations on the glass substrate as long as it has a composition that can be strengthened by chemical treatment, but glass containing alkali metal ions or alkaline earth metal ions with a smaller ionic radius is preferred. Specific examples include soda-lime glass, alkali silicate glass, alkali aluminosilicate glass, aluminoborosilicate glass, and borosilicate glass. Among these, those containing sodium ions are preferred, and glass containing 5% by weight or more of sodium ions is most preferred. Alkali aluminosilicate glass is preferably used because it has a high potassium ion substitution level, which allows for a deeper strengthening layer, and it has high transparency. The thickness of the glass substrate is usually 2 mm to 8 mm. If it is less than 2 mm, the strength required for tempered glass may be insufficient and it is not suitable for chemical tempering by ion exchange. There are no particular restrictions on the area of ​​the substrate, and it can be determined arbitrarily based on the size of the final product and constraints of the manufacturing process.

[0015] <Anti-reflective film> An antireflection film is usually laminated on the glass substrate. However, an antistatic layer, a silica particle layer, a primer layer, or a smoke layer may be provided between the glass substrate and the antireflection film for the purposes of improving antistatic properties, antiglare properties, and adhesion, and further preventing transmission of visible light, within a range that does not deteriorate bending properties. The antireflection film in the present invention is a multi-layer antireflection film composed of three refractive index layers having the following properties. Medium refractive index layer: refractive index of 1.67 to 1.87, layer thickness of 35 to 120 nm High refractive index layer: refractive index 1.90 to 2.05, layer thickness 30 to 115 nm Low refractive index layer: refractive index of 1.34 to 1.45, layer thickness of 45 to 120 nm The three refractive index layers are arranged in the order of the medium refractive index layer, the high refractive index layer, and the low refractive index layer from the glass substrate side. By using the above three-layer antireflection film, both the antireflection glass and the antireflection tempered glass have an average luminous reflectance of 0.6% or less on both sides in the wavelength range of 380 to 780 nm and an average luminous transmittance of 99% or more in the wavelength range of 380 to 780 nm, thereby providing high-performance antireflection products.

[0016] <Medium refractive index layer> This is the refractive index layer located at the bottom of the anti-reflection coating (on the glass substrate side). It is usually laminated on the glass substrate. The refractive index of the medium refractive index layer is 1.67 to 1.87, and the layer thickness is 35 to 120 nm, preferably 1.70 to 1.76, and 80 to 100 nm.

[0017] The medium refractive index layer needs to be glass-strengthened by chemical treatment after the formation of the anti-reflection film and the protective layer. Therefore, it is preferable to prepare a curable composition for forming the medium refractive index layer (medium refractive index layer-forming solution) containing the following components, and then form the layer by coating, drying, and heating the solution. Specifically, the curable composition contains 25 to 70 parts by mass of metal oxide particles relative to 100 parts by mass of a binder component consisting of an alkoxysilane compound represented by the following formula (1) or a partial hydrolyzate thereof (hereinafter also referred to as an alkoxysilane compound, etc.). R n -Si(OR1) 4-n (1) (In the formula, R is an alkyl group, an alkenyl group, or an alkoxyalkyl group, R1 is an alkyl group, an alkoxyalkyl group, or a halogen atom, and n is an integer of 0, 1, or 2.)

[0018] [Alkoxysilane Compound or Partial Hydrolyzate thereof] This component acts as a binder to form a dense, high-strength layer that has good adhesion to the glass substrate, and is represented by the above formula (1). In the formula, R is an alkyl group, an alkenyl group, or an alkoxyalkyl group. The number of carbon atoms in the alkyl group is preferably 1 to 9, more preferably 1 to 5. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group. The number of carbon atoms in the alkenyl group is preferably 1 to 9, more preferably 1 to 5. Examples of the alkenyl group include an ethenyl group, a propenyl group, a butenyl group, a penyl group, and a hexenyl group. The number of carbon atoms in the alkoxyalkyl group is preferably 1 to 9, more preferably 1 to 5. Examples of the alkoxy group in the alkoxyalkyl group include a methoxy group, an ethoxy group, a propoxy group, etc. Examples of the alkyl group in the alkoxyalkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, etc. In the formula, R1 is an alkyl group, an alkoxyalkyl group, or a halogen atom. The alkyl group and alkoxyalkyl group are the same as those of R. Examples of halogen atoms include fluorine, chlorine, bromine, and iodine. Specific examples of alkoxysilane compounds include methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, tetramethoxysilane, tetraethoxysilane, tetra-n-butoxysilane, and vinyltriethoxysilane.

[0019] [Metal oxide particles] The medium refractive index layer contains metal oxide particles to control the refractive index to the predetermined value. The metal oxide particles may have a refractive index of 1.50 or higher, and are preferably at least one oxide selected from the group consisting of titanium oxide, zirconium oxide, niobium pentoxide, antimony-doped tin oxide (ATO), indium oxide-tin oxide (ITO), phosphorus-doped tin oxide (PTO), fluorine-doped tin oxide (FTO), and antimony pentoxide. More specifically, the metal oxide particles include titanium oxide particles (refractive index = 2.71) and composite titanium metal oxide particles in which titanium oxide is combined with other oxides such as silicon oxide or zirconium oxide at the molecular level to adjust the refractive index. These metal oxide particles are appropriately combined to adjust the desired refractive index. Such particles are known per se and commercially available.

[0020] The average particle size of the metal oxide particles is preferably 1 to 100 nm, more preferably 1 to 70 nm. The refractive index of the metal oxide particles is preferably 2.00 to 2.90, more preferably 2.10 to 2.80. In the present invention, the average particle size refers to the particle size at which the cumulative volume is 50% in the particle size distribution measured by a laser diffraction / scattering method. The content of the metal oxide particles in the medium-refractive index layer composition is appropriately selected from the range of 25 to 70 parts by mass, preferably 25 to 50 parts by mass, relative to 100 parts by mass of the alkoxysilane compound, etc., so as to satisfy the predetermined refractive index, taking into consideration changes in refractive index caused by shrinkage of the alkoxysilane compound, etc. due to thermal history. In particular, titanium oxide particles with a high refractive index are preferably used for the purpose of designing the medium-refractive index layer to have a high refractive index and for the purpose of suppressing layer shrinkage itself by maintaining a balance between the refractive index fluctuations with the high-refractive index layer.

[0021] [Solution for forming medium refractive index layer] The above components constituting the medium refractive index layer are dissolved in the following organic solvents, together with optional components as needed, to form a curable composition for forming the medium refractive index layer (hereinafter also referred to as a medium refractive index layer-forming solution) for adjusting viscosity and for ease of application. An appropriate amount of an aqueous acid solution, such as an aqueous hydrochloric acid solution, can be blended into the solution to promote hydrolysis and condensation of the alkoxysilane compound.

[0022] Typical organic solvents include alcoholic solvents such as methanol, ethanol, isopropanol, ethyl cellosolve, and ethylene glycol; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and aromatic solvents such as toluene and xylene. Alcoholic solvents are particularly preferred. When a commercially available metal oxide particle dispersion is used, the dispersion medium is inevitably mixed into the solution for forming the medium refractive index layer. The dispersion medium in the solution and the organic solvent added separately are removed in the subsequent drying and heat curing steps. The amount of organic solvent used may be such that the viscosity of the forming solution is in a range suitable for coating without causing dripping, etc. Generally, the organic solvent is used in an amount such that the total solids concentration is 0.1 to 20 wt % of the total weight. Note that the amount of organic solvent is a value including the amount of the dispersion medium of the metal oxide particle dispersion.

[0023] [Formation of Medium Refractive Index Layer] The above-mentioned solution for forming a medium refractive index layer is applied to the glass substrate, dried, and then heated and cured to form a medium refractive index layer. However, from the viewpoint of productivity and adhesion of each layer of the antireflection film, it is preferable to carry out the thermal curing step by heating all at once after similarly applying and drying the high refractive index layer and the low refractive index layer described below. Furthermore, it is particularly preferable to apply and dry the protective layer in the same way, and then heat and thermally cure all layers of the antireflection film and the protective layer all at once. The coating method is not particularly limited, and methods such as dip coating, roll coating, die coating, flow coating, and spraying can be used, but dip coating is preferred from the viewpoint of appearance quality and layer thickness control. Drying is usually carried out in the atmosphere at a temperature of 70 to 100° C. for 0.25 to 1 hour, and heating for thermal curing is usually carried out in the atmosphere at 300 to 500° C. for 0.5 to 2 hours.

[0024] <High refractive index layer> This refractive index layer is laminated on the medium refractive index layer (on the viewing side) and has a refractive index higher than that of the medium refractive index layer. The high refractive index layer has a refractive index of 1.90 to 2.05 and a thickness of 30 to 115 nm, preferably 1.95 to 2.03 and 45 to 100 nm.

[0025] The present invention is characterized by the use of a metal alkoxide oligomer instead of conventional metal oxide particles to achieve a high refractive index and prevent cracks from occurring in each layer during bending processing. When the metal alkoxide oligomer is used, an even higher refractive index is achieved and the usable life of the high refractive index layer-forming solution is also extended. Metal alkoxide oligomers are oligomers that have, for example, titanoxane bonds in the molecule, formed by partial hydrolysis and condensation of an alkoxyzirconium compound or an alkoxytitanium compound. The method for producing such oligomers is described in detail in JP 2015-3896 A, and typically, they are produced by hydrolyzing an alkoxytitanium such as tetrabutoxytitanium in the presence of pyrazolone hydrochloride. Such oligomers are commercially available. Furthermore, since the high refractive index layer does not contain oxide particles for adjusting the refractive index, it is possible to prevent ultraviolet rays from passing through the gaps between the particles, thereby improving weather resistance.

[0026] [Solution for forming high refractive index layer] The metal alkoxide oligomer, which is the main component of the high refractive index layer, is dissolved in the organic solvent together with optional components that are blended as needed to form a curable composition (solution for forming a high refractive index layer) for forming a high refractive index layer. The amount of organic solvent used may be such that the viscosity of the forming solution is in a range suitable for coating without causing dripping or the like. Generally, the organic solvent is used in an amount such that the metal alkoxide oligomer accounts for 0.1 to 20 wt % of the total weight. Note that, when a commercially available metal alkoxide oligomer is used, the amount of organic solvent includes the amount of solvent such as alcohol in which the metal alkoxide oligomer is dissolved.

[0027] [Formation of high refractive index layer] The solution for forming a high refractive index layer is applied onto the medium refractive index layer, dried, and then heated and cured to form a high refractive index layer. The coating method, drying conditions, heating conditions, etc. are the same as those for forming the medium refractive index layer, and it is also preferable to heat the entire layer at once to perform thermal curing.

[0028] <Low refractive index layer> This is the refractive index layer located on the outermost layer (viewing side) of the anti-reflection film, and is the layer that contributes most to the anti-reflection performance. The low refractive index layer has a refractive index of 1.34 to 1.45 and a thickness of 45 to 120 nm, preferably 1.37 to 1.42 and 55 to 90 nm.

[0029] The low refractive index layer needs to be glass-strengthened by chemical treatment after the formation of the antireflection film and the protective layer. In order to further exhibit alkali resistance, it is preferable to prepare a curable composition for forming the low refractive index layer (solution for forming the low refractive index layer) containing the following components, and then form the layer by coating, drying, and heating the solution. Specifically, the curable composition contains 100 parts by mass of a binder component consisting of an alkoxysilane compound represented by the formula (1) or a partial hydrolyzate thereof, 1 to 15 parts by mass of hollow silica particles, and 1 to 10 parts by mass of an aluminum salt hydrate.

[0030] [Alkoxysilane Compound or Partial Hydrolyzate thereof] The compound is represented by the formula (1), and is as described in the section on the medium refractive index layer. The alkoxysilane compound used in forming the medium refractive index layer can be used for the same purpose.

[0031] [Hollow Silica Particles] In the low refractive index layer of the present invention, hollow silica particles are used to control the refractive index to 1.34 to 1.45. Hollow silica particles are particles made of silicon dioxide with an internal cavity. They are typically minute hollow particles with a particle diameter of 5 to 150 nm and an outer shell thickness of approximately 1 to 15 nm. Ion exchange is performed using the internal cavity. In order to control the refractive index of the low refractive index layer within the above range, it is preferable to select hollow silica particles with a refractive index in the range of 1.20 to 1.38. The hollow silica particles are known, for example, from JP-A-2001-233611, and are generally commercially available in the form of a dispersion in a lower alcohol such as methanol, ethanol, or propanol. Therefore, it is preferable to obtain and use a commercially available product.

[0032] The hollow silica particles are used in an amount appropriately selected from the range of 1 to 15 parts by mass, preferably 3 to 10 parts by mass, per 100 parts by mass of the alkoxysilane compound, etc., so as to satisfy the predetermined refractive index, taking into consideration factors such as changes in refractive index due to thermal history and the balance of refractive index with the medium refractive index layer and the high refractive index layer. In particular, by setting the content within the above-mentioned relatively low range and increasing the refractive index, the weather resistance is improved. This is thought to be due to the fact that the reduction in the content of hollow silica particles reduces the number of cavities through which ultraviolet light that deteriorates each layer of the anti-reflection film passes, and that the binder component increases in proportion to the reduction, increasing the crosslink density of the layer and making it more difficult for ultraviolet light to pass through.

[0033] [Aluminum salt hydrate] In order to impart a high degree of alkali resistance to the anti-reflection glass of the present invention, it is preferable that the low refractive index layer and the protective layer contain an aluminum salt hydrate. Tempered glass requires an alkaline cleaning process to prevent the tempered glass from becoming frosted and losing its transparency after commercialization (to prevent discoloration).Alkaline cleaning is also performed for various purposes, such as removing impurities that may have adhered to the glass during tempering. Specifically, there are two types of discoloration: blue discoloration, which occurs when the glass surface becomes depleted of alkali ions due to erosion by moisture in the air, and white discoloration, which occurs when moisture containing alkali ions on the glass surface dries and concentrates, and carbon dioxide gas produces carbonate compounds. Once these types of discoloration occur, they are difficult to repair without physical surface polishing. However, such alkaline cleaning may damage the antireflection film formed on the glass surface, causing it to become uneven and mottled, or may reduce the film thickness, resulting in problems such as failure to exhibit the desired antireflection ability or a change in color, resulting in loss of product value.

[0034] Aluminum salt hydrates are hydrated compounds in which water molecules are added to aluminum salts in the form of crystal water, coordination water, etc. Non-hydrated aluminum salts have poor affinity with other components and may aggregate or precipitate during mixing. In particular, anhydrous salts, which are hygroscopic, react with moisture in the air during coating, making it difficult to achieve uniformity and forming a low refractive index layer. Furthermore, other metal salt hydrates exhibit poor alkali resistance. Aluminum is a metal with which the binder component can be coordinated, and aluminum oxide, which is resistant to alkali, is formed in the refractive index layer, which is presumably why alkali resistance is achieved.

[0035] Representative examples of aluminum salt 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. From the viewpoints of alkali resistance and scratch resistance, aluminum chloride trihydrate and aluminum chloride hexahydrate are particularly preferred. When an aluminum salt hydrate is contained in a low refractive index layer, the amount is 1 to 10 parts by mass per 100 parts by mass of the alkoxysilane compound, etc. If the amount is less than 1 part by mass, the effect is not obtained. If the amount exceeds 10 parts by mass, the aluminum salt hydrate is excessively coordinated to the alkoxysilane compound, etc., reducing the intermolecular bond strength of the alkoxysilane compound, etc. itself, which leads to a decrease in layer hardness, which is not preferable.

[0036] [Low refractive index layer forming solution] The above-mentioned components constituting the low refractive index layer are dissolved in the above-mentioned organic solvent together with optional components such as an aqueous acid solution as needed to prepare a solution for forming the low refractive index layer. When a commercially available hollow silica particle dispersion is used, the amount of the organic solvent used includes the amount of the dispersion medium.

[0037] [Formation of low refractive index layer] The solution for forming a low refractive index layer is applied onto the high refractive index layer, dried, and then heated and cured to form a low refractive index layer. The coating method, drying conditions, heating conditions, etc. are the same as those for forming the medium refractive index layer, and it is also preferable to heat the entire layer at once to perform thermal curing.

[0038] <Protective layer> A protective layer is provided on the anti-reflection film (on the viewing side) to prevent the anti-reflection film from being damaged by external impacts such as scratches, and also to prevent damage to the anti-reflection film from ion collisions during chemical strengthening. The protective layer has a refractive index of 1.42 to 1.48 and a thickness of 5 to 50 nm, preferably a refractive index of 1.42 to 1.46 and a thickness of 10 to 30 nm.

[0039] The protective layer is preferably formed by preparing a curable composition (protective layer-forming solution) for forming the protective layer, which contains 100 parts by mass of a binder component consisting of an alkoxysilane compound represented by the formula (1) or a partial hydrolyzate thereof, 1 to 25 parts by mass of a metal chelate compound, and 1 to 20 parts by mass of an aluminum salt hydrate, and then coating, drying, and heating the solution.

[0040] [Metal chelate compounds] This component functions as a crosslinking agent, making the formed layer denser. The metal chelate compound is a compound in which a chelating agent, typically a bidentate ligand, is coordinated to a metal such as titanium, zirconium, or aluminum. Specifically, titanium chelate compounds such as triethoxy mono(acetylacetonate)titanium, diethoxy bis(acetylacetonate)titanium, monoethoxy tris(acetylacetonate)titanium, tetrakis(acetylacetonate)titanium, triethoxy mono(ethylacetoacetate)titanium, diethoxy bis(ethylacetoacetate)titanium, monoethoxy tris(ethylacetoacetate)titanium, mono(acetylacetonate)tris(ethylacetoacetate)titanium, bis(acetylacetonate)bis(ethylacetoacetate)titanium, and tris(acetylacetonate)mono(ethylacetoacetate)titanium; Zirconium chelate compounds such as triethoxy mono(acetylacetonate)zirconium, diethoxy bis(acetylacetonate)zirconium, monoethoxy tris(acetylacetonate)zirconium, tetrakis(acetylacetonate)zirconium, triethoxy mono(ethylacetoacetate)zirconium, diethoxy bis(ethylacetoacetate)zirconium, monoethoxy tris(ethylacetoacetate)zirconium, tetrakis(ethylacetoacetate)zirconium, mono(acetylacetonate)tris(ethylacetoacetate)zirconium, bis(acetylacetonate)bis(ethylacetoacetate)zirconium, and tris(acetylacetonate)mono(ethylacetoacetate)zirconium; Aluminum chelate compounds such as diethoxy mono(acetylacetonate)aluminum, monoethoxy bis(acetylacetonate)aluminum, di-i-propoxy mono(acetylacetonate)aluminum, monoethoxy bis(ethylacetoacetate)aluminum, diethoxy mono(ethylacetoacetate)aluminum, and tris(acetylacetonate)aluminum Examples include:

[0041] The metal chelate compound is used in an amount of 1 to 25 parts by mass, preferably 5 to 20 parts by mass, per 100 parts by mass of the alkoxysilane compound, etc. If the amount exceeds 25 parts by mass, the metal chelate compound will crystallize in the protective layer, causing a decrease in anti-reflection performance and poor appearance. If the amount is less than 1 part by mass, the strength and hardness of the layer will decrease, and the layer will tend not to function as a protective layer.

[0042] [Aluminum salt hydrate] The aluminum salt hydrate used in forming the low refractive index layer can be used for the same purpose. The aluminum salt hydrate is used in an amount of 1 to 20 parts by mass, preferably 3 to 15 parts by mass, per 100 parts by mass of the alkoxysilane compound, etc. If it exceeds 20 parts by mass, the layer hardness tends to decrease. If it is less than 1 part by mass, it is difficult to achieve alkali resistance.

[0043] [Protective layer forming solution] The above-mentioned components constituting the protective layer are dissolved in the organic solvent together with optional components such as an aqueous acid solution as required to prepare a solution for forming the protective layer.

[0044] [Formation of protective layer] The above-mentioned protective layer forming solution is applied onto the low refractive index layer, dried, and then heated and cured to form a protective layer. The coating method, drying conditions, heating conditions, etc. are the same as those for forming the medium refractive index layer, and it is also the same that all layers including the antireflection film are preferably heated together for thermal curing.

[0045] <Glass strengthening by chemical treatment> The anti-reflective glass of the present invention is tempered by chemical treatment to form tempered anti-reflective glass. Chemical treatment strengthens glass by replacing metal ions with small ionic radii (e.g., sodium ions) with metal ions with larger ionic radii (e.g., potassium ions). By replacing metal ions with larger ionic radii, a compressive stress layer forms on the glass surface. As a result, breaking this glass requires not only a force to break the intermolecular bonds but also a force to remove the compressive stress on the surface, significantly improving its strength compared to ordinary glass. A conventionally known chemical treatment method is employed, typically by contacting untempered anti-reflective glass with a molten metal salt of potassium salt such as potassium nitrate at a temperature in the range of 390°C to 450°C for 3 to 16 hours to replace sodium ions with large ionic radius potassium ions, thereby producing high-strength tempered glass.

[0046] <Alkaline cleaning> Before or after the glass strengthening process, alkaline cleaning is carried out for the purpose of removing organic and inorganic substances adhering to the glass surface, preventing the glass from becoming ground glass and losing its transparency (preventing discoloration), and for other reasons. For alkaline cleaning, commercially available alkaline cleaning solutions with a pH of approximately 12 to 13 are prepared by dissolving strong alkaline compounds such as sodium hydroxide and potassium hydroxide, surfactants, etc. in alcohol-based solvents or water. These cleaning solutions are diluted appropriately with water or the like depending on the purpose and conditions of alkaline cleaning. The alkaline cleaning is usually carried out at room temperature to 55°C for about 0.1 to 0.5 hours, and then the substrate is washed with water or an organic solvent to wash away the alkaline cleaning solution. [Example]

[0047] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Furthermore, not all of the combinations of features described in the examples are necessarily essential to the solution of the present invention. The various components, abbreviations, and test methods used in the following examples and comparative examples are as follows:

[0048] [Aluminum salt hydrate] AlCl3·6H2O: Aluminum chloride hexahydrate [Alkoxysilane compounds, etc.] TEOS: Tetraethoxysilane [Metal chelate compounds] Aluminum D: Monoacetylacetonate bis(ethylacetoacetonate)aluminum [Silica particles] Hollow silica particles: Average particle size 40 nm, refractive index 1.25, solid content 20 wt.% Dispersion solvent IPA [Metal oxide particles] Titanium oxide particles: Average particle size 108.8 nm, refractive index 2.71, solid content 15 wt.%, Dispersion solvent: methanol [Metal Alkoxide Oligomer] Ti Oligomer: An oligomer prepared using tetra(n-butoxy)titanium as the main raw material Solvent: normal butyl alcohol [Organic solvent] IPA: Isopropyl alcohol BuOH: normal butyl alcohol Ethacol: Ethyl alcohol / isopropyl alcohol mixture NPA: normal propyl alcohol SBAC: acetic acid s-butyl ester [Hydrolysis catalyst] HCl: 0.05N hydrochloric acid 〔others〕 TTB: tetrabutoxytitanium(IV) [Glass substrate] Glass 1.1: Soda lime glass (50mm x 88mm x 1.1mm)

[0049] [Refractive index of each refractive index layer] The solution for forming each refractive index layer was applied to a glass substrate to a thickness of 100 nm and cured to form each refractive index layer or protective layer. The reflectance of each layer was measured using a JASCO V-650 spectrophotometer, and the refractive index was calculated.

[0050] [Average visual reflectance on both sides] The average luminous reflectance of both surfaces (hereinafter also referred to as average luminous reflectance) was measured by the following method. Measurements were taken at 380nm to 780nm using a JASCO V-650 UV-Visible Spectrophotometer, and the values ​​were calculated by multiplying by a weighting factor based on JIS Z 8722. The product measured was anti-reflective glass, which had an anti-reflective film and a protective layer formed on both sides of the glass substrate. Note that these measurements were for anti-reflective glass before the glass was tempered, but it was confirmed that these values ​​hardly changed after the glass was tempered.

[0051] [Luminous average transmittance] The average luminous transmittance was measured using a JASCO V-650 UV-Visible Spectrophotometer at 380 nm to 780 nm, and calculated by multiplying the measured value by a weighting factor based on JIS Z 8722. Note that these measurements were for the anti-reflective glass before glass strengthening, but it was confirmed that these values ​​hardly changed after glass strengthening.

[0052] [Bending properties] The bending test is a test method in which a glass test piece is placed on a bending mold and subjected to one cycle of heating, heating to form the bend, and slow cooling using an electric furnace, and involves either gravity bending or hot bending using a press. In this test, soda-lime glass was used, and heating and forming were carried out at 600°C ± 10°C for 10 to 30 minutes, followed by gravity bending so that the elongation of the glass surface was 5%. The elongation rate was measured and calculated as follows: The width (w) and height (h) of the arc on the outermost surface of the bent glass were measured, and the R value of the outermost surface of the glass was calculated according to the following known formula.

[0053]

number

[0054] Next, the elongation rate was determined according to the following formula using the obtained R value, the glass thickness (t), and θ=90° (right-angle bending condition).

[0055]

number

[0056] The surface of the bent portion was observed with a laser microscope, and the absence of cracks in the direction perpendicular to the stretching direction was used as the evaluation criterion. ○: No cracks ×: Cracks occurred

[0057] [Weather resistance: Accelerated weather resistance test] The weather resistance test was carried out using a sunshine carbon arc lamp at BP 63°C, 50% RH (relative humidity), and for 2000 hours. The measuring equipment, conditions, and method were based on JIS B 7753. A cross-cut peeling tape test was carried out and evaluation was carried out based on the absence of peeling of the anti-reflection film and protective layer. ○: No film peeling ×: Film peeling

[0058] [Alkali resistance of anti-reflective coating] In order to examine the alkali resistance of the antireflective film after alkali cleaning, the film was subjected to alkali cleaning by the following method, and the change in color of the antireflective tempered glass before and after alkali cleaning was observed with the naked eye and evaluated according to the following criteria. The obtained anti-reflective glass was subjected to alkaline cleaning by immersion in a diluted solution of Yokohama Yushi Kogyo Co., Ltd.'s "Semiclean MG; pH = 12.4" diluted to 5 wt% with water at 40°C for 10 minutes under ultrasonic waves, and then the cleaning solution was rinsed off with warm water and IPA. Next, the glass was subjected to chemical strengthening treatment by immersion in a molten solution of potassium nitrate at 390°C for 16 hours to produce anti-reflective tempered glass. The anti-reflective glass (untempered) is colorless and transparent. Evaluation was carried out on the anti-reflective tempered glass after tempering. "◎" and "◯" indicate that the anti-reflection film was not optically altered by the alkaline cleaning, while "×" indicates that the anti-reflection film was clearly peeled off. ◎: No change ○: Color change is observed but no peeling ×: Film peeling

[0059] [Glass strength: compressive stress measurement] Using the Orihara Manufacturing Co., Ltd. "FSM-6000LE," we measured the surface stress CS (MPa) and stress layer depth DOL (μm) due to the difference in refractive index (caused by ion substitution) on the surface of chemically strengthened glass. The higher the CS and DOL values, the greater the degree of strengthening. A DOL value of 10 μm or more fully functions as strengthened glass.

[0060] [Preparation of solution for forming medium refractive index layer] The components shown in Table 1 were mixed in the amounts shown in the same table to prepare solutions (m-1 to m-5) for forming a medium refractive index layer.

[0061] [Table 1]

[0062] [Preparation of high refractive index layer forming solution] The components shown in Table 2 were mixed in the amounts shown in the same table to prepare solutions for forming high refractive index layers (h-1 to h-3). h-2 is a solution containing tetraalkoxy metal instead of metal alkoxide oligomer, and h-3 is a solution containing metal oxide particles.

[0063] [Table 2]

[0064] [Preparation of low refractive index layer forming solution] The components shown in Table 3 were mixed in the amounts shown in the same table to prepare solutions (l-1 to l-9) for forming low refractive index layers. l-9 is a solution that does not contain aluminum salt hydrates.

[0065] [Table 3]

[0066] [Preparation of protective layer forming solution] The components shown in Table 4 were mixed in the amounts shown in the same table to prepare solutions for forming protective layers (cv-1 to cv-8). CV-7 is a solution without aluminum salt hydrate, and CV-8 is a solution with excess aluminum salt hydrate.

[0067] [Table 4]

[0068] Example 1 Glass 1.1 (glass substrate) was dipped in the medium refractive index layer forming solution (m-2) and then dried at 100°C for 15 minutes to form a semi-cured medium refractive index layer with a layer thickness of 86 nm on the glass substrate. It is believed that the medium refractive index layer was in an insufficiently cured state (semi-cured) due to drying under the above conditions, and the same applies to each of the following layers. The layer thickness was adjusted by the lifting speed from the medium refractive index layer forming solution into which it was dipped. The same applies to each of the following layers. Next, the glass substrate was dipped in a high refractive index layer forming solution (h-1) and then dried at 100°C for 15 minutes to form a semi-cured high refractive index layer with a layer thickness of 51 nm on the semi-cured medium refractive index layer. Next, the glass substrate was dipped in the low refractive index layer forming solution (l-1) and then dried at 100°C for 15 minutes to form a semi-cured low refractive index layer with a thickness of 88 nm on the semi-cured high refractive index layer. The glass substrate was then dipped in a protective layer forming solution (cv-1) and dried at 100° C. for 15 minutes to form a semi-cured protective layer with a thickness of 10 nm on the semi-cured low refractive index layer. The glass substrate on which the semi-cured antireflection film and the protective layer were laminated was heated at 300° C. for 30 minutes for thermal curing, thereby producing an antireflection glass of the present invention.

[0069] The average luminous reflectance and average luminous transmittance of the obtained anti-reflection glass were measured according to the above-mentioned method, and are shown in Table 5 together with the thickness and refractive index of each layer. The antireflective glass was then subjected to alkali cleaning and glass strengthening by the following method. The antireflective glass was immersed in a diluted solution of Yokohama Yushi Kogyo Co., Ltd.'s "Semiclean MG; pH = 12.4" diluted to 5 wt% with water at 40°C for 10 minutes under ultrasonic waves to perform alkali cleaning, and then the cleaning solution was rinsed off with warm water and IPA. Next, the glass was immersed in a molten potassium nitrate solution at 390°C for 16 hours to perform chemical strengthening, resulting in antireflective tempered glass. The bending properties, weather resistance, glass strength, and alkali resistance of the obtained anti-reflective tempered glass were measured according to the methods described above. The results are shown in Table 5.

[0070] Examples 2 to 16 Anti-reflection glass and anti-reflection tempered glass were produced in the same manner as in Example 1, except that the refractive index layer-forming solutions and protective layer-forming solutions were used in the combinations shown in Tables 5 and 6. The average luminous reflectance and average luminous transmittance of the obtained anti-reflective glass, the thickness and refractive index of each layer, and the bending properties, weather resistance, glass strength, and alkali resistance of the anti-reflective tempered glass are shown in Tables 5 and 6. When the high refractive index layer was made of a cured product of a curable composition containing a metal alkoxide oligomer, no cracks occurred in the protective layer and the anti-reflection film when bent at an elongation rate of 5%.

[0071] [Table 5]

[0072] [Table 6]

[0073] Comparative Examples 1 to 14, Reference Examples 1 to 6 Anti-reflection glass and anti-reflection tempered glass were produced in the same manner as in Example 1, except that the refractive index layer-forming solutions and protective layer-forming solutions were used in the combinations shown in Tables 7 and 8. The average luminous reflectance and average luminous transmittance of the obtained anti-reflective glass, the thickness and refractive index of each layer, and the bending properties, weather resistance, glass strength, and alkali resistance of the anti-reflective tempered glass are all shown in Tables 7 and 8.

[0074] [Table 7]

[0075] [Table 8]

[0076] Comparative Example 1 is a case where the refractive index of the low refractive index layer is high, and Comparative Example 2 is a case where the refractive index of the low refractive index layer is low, and both cases were inferior in antireflection performance. Comparative Example 3 was a case where the refractive index of the medium refractive index layer was low, and Comparative Example 4 was a case where the refractive index of the medium refractive index layer was high, and both cases were inferior in antireflection performance. Comparative Example 5 is a case where the low refractive index layer is thin, and Comparative Example 6 is a case where the low refractive index layer is thick, and both cases were inferior in antireflection performance. Comparative Example 7 is a case where the high refractive index layer is thin, and Comparative Example 8 is a case where the high and low refractive index layers are thick, and in both cases the antireflection ability was insufficient. Comparative Example 9 was a case where the thickness of the medium refractive index layer was thin, and Comparative Example 10 was a case where the thickness of the medium refractive index layer was thick, and in both cases the antireflection ability was insufficient. Comparative Example 11 was a case in which a silane coupling agent and titanium oxide particles were used in place of the metal alkoxide oligomer in the high refractive index layer, and the antireflection performance was insufficient. In Comparative Example 12, a tetraalkoxy metal was used in place of a metal alkoxide oligomer for the high refractive index layer, and the forming solution hardened quickly, causing variations in the layer thickness, and the refractive index during thermal hardening varied greatly and was uncontrollable. Therefore, it was not possible to measure the antireflection ability and other properties. Comparative Example 13, in which the protective layer was thin, was poor in alkali resistance, and Comparative Example 14, in which the protective layer was thick, was poor in average luminous reflectance.

[0077] Reference Example 1 was a case in which no metal chelate compound was used in the protective layer, and the alkali resistance was poor. Reference Example 2 was a case in which an excessive amount of metal chelate compound was used in the protective layer, and the bending properties were poor. Reference Example 3 was a case in which no aluminum salt hydrate was used in the protective layer, and the alkali resistance was poor. In Reference Example 4, an excessive amount of aluminum salt hydrate was used in the protective layer, and the protective layer turned white, failing to exhibit anti-reflection properties. In Reference Example 5, an excessive amount of aluminum salt hydrate was used in the low refractive index layer, and the low refractive index layer was whitened, failing to exhibit anti-reflection properties. Reference Example 6 is a case where no aluminum salt hydrate was used in the low refractive index layer, and although sufficient reflection characteristics and bending characteristics were exhibited, alkali resistance was poor.

Claims

1. An anti-reflection glass having a glass substrate, an anti-reflection film, and a protective layer in this order, The anti-reflection film is formed by, in order from the glass substrate side, a medium refractive index layer having a refractive index of 1.67 to 1.87 and a layer thickness of 35 to 120 nm; a high refractive index layer having a refractive index of 1.90 to 2.05 and a layer thickness of 30 to 115 nm; a low refractive index layer having a refractive index of 1.34 to 1.45 and a layer thickness of 45 to 120 nm; Equipped with the protective layer has a refractive index of 1.42 to 1.48 and a thickness of 5 to 50 nm; the high refractive index layer is made of a cured product of a curable composition containing a metal alkoxide oligomer (the metal is a titanium atom or a zirconium atom); An anti-reflection glass characterized in that the average luminous reflectance on both sides is 0.6% or less, and cracks do not occur in the protective layer and the anti-reflection film when bent with an elongation of the glass surface of 5% or less.

2. 2. The anti-reflective glass according to claim 1, wherein the medium-refractive index layer comprises a cured product of a curable composition containing 25 to 70 parts by mass of metal oxide particles relative to 100 parts by mass of a binder component made of an alkoxysilane compound represented by the following formula (1) or a partial hydrolyzate thereof: R ｎ -Si(OR １ ) ４－ｎ (1) (wherein R is an alkyl group, an alkenyl group, or an alkoxyalkyl group; R １ is an alkyl group, an alkoxyalkyl group, or a halogen atom, and n is an integer of 0, 1, or 2.

3. 2. The anti-reflection glass according to claim 1, wherein the low refractive index layer comprises a cured product of a curable composition containing 1 to 15 parts by mass of hollow silica particles and 1 to 10 parts by mass of aluminum salt hydrate, relative to 100 parts by mass of a binder component made of an alkoxysilane compound represented by the following formula (1) or a partial hydrolyzate thereof: R ｎ -Si(OR １ ) ４－ｎ (1) (wherein R is an alkyl group, an alkenyl group, or an alkoxyalkyl group; R １ is an alkyl group, an alkoxyalkyl group, or a halogen atom, and n is an integer of 0, 1, or 2.

4. 2. The anti-reflective glass according to claim 1, wherein the protective layer comprises a cured product of a curable composition containing 100 parts by mass of a binder component made of an alkoxysilane compound represented by the following formula (1) or a partial hydrolyzate thereof, 1 to 25 parts by mass of a metal chelate compound, and 1 to 20 parts by mass of an aluminum salt hydrate: R ｎ -Si(OR １ ) ４－ｎ (1) (wherein R is an alkyl group, an alkenyl group, or an alkoxyalkyl group; R １ is an alkyl group, an alkoxyalkyl group, or a halogen atom, and n is an integer of 0, 1, or 2.

5. 5. The anti-reflection glass according to claim 1, wherein the anti-reflection film and the protective layer are not peeled off in an accelerated weather resistance test at a temperature of 63° C., a humidity of 50% RH (relative humidity) and a test time of 2000 hours.

6. 5. The anti-reflective glass according to claim 1, wherein the anti-reflective glass is a chemically strengthened anti-reflective glass.

7. A method for producing tempered anti-reflective glass, comprising heating and bending the anti-reflective glass according to any one of claims 1 to 4, and then chemically tempering the glass in a molten solution of a metal salt for ion exchange.

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