Glass article

Abstract

To provide a novel glass article.　Provided is a glass article having a refractive index of 1.60 or more and a compressive stress layer on a surface, wherein the value of the product of the compressive stress layer depth DOL and the surface compressive stress CS is 18,000 MPa∙μm or more.

Description

Glass articles

[0001] The present invention relates to a glass article.

[0002] Glass has been used in a variety of products. Among them, glass with a high refractive index has been used for decorative purposes. Crystal glass containing lead is known as a high refractive index glass, but lead-free high refractive index glass is being investigated.

[0003] For example, Patent Document 1 discloses a decorative glass article having a refractive index of 1.9 or more and an Abbe number of 42 or less. The decorative glass article disclosed in Patent Document 1 is described as having excellent brilliance and fire (rainbow-colored brilliance).

[0004] Japanese Patent Application Laid-Open No. 2020-172427

[0005] Here, decorative glass is expected to have a variety of uses, and new glass articles have been desired.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel glass article.

[0007] The present inventors have conducted extensive research into the above-mentioned problems and have completed the present invention.

[0008] That is, the inventors have found that the above problems can be solved by the following configurations. [1] A glass article having a refractive index nd of 1.60 or more and having a compressive stress layer on its surface, wherein the product of the compressive stress layer depth DOL and the surface compressive stress CS is 18,000 MPa μm or more. [2] The glass article according to [1], wherein the surface compressive stress CS is 400 MPa or more. [3] The glass article according to [1] or [2], wherein the compressive stress layer depth DOL is 30 μm or more. [4] The glass article according to [1] or [2], wherein the refractive index nd exceeds 1.70. [5] The glass article according to [1] or [2], wherein the composition of the central portion contains Li ２ [6] The glass article according to [1] or [2], wherein the content of O is 7.0% or more in mole percent on an oxide basis. ２O, Na ２ O and K ２ [7] The glass article according to [1] or [2], wherein the total content of O is 12.0% or more in mole percent on an oxide basis. ２ The glass article according to [1] or [2], wherein the content of is 10.0% or more, expressed as mole % on an oxide basis. [8] The glass article according to [1] or [2], wherein the Young's modulus is 90 GPa or more. [9] The glass article according to [1] or [2], wherein, when molded into a measurement sample having a thickness of 1 mm, the difference between the maximum and minimum values ​​of transmittance at wavelengths of 400 to 800 nm is 10.0% or less.

[10] The glass article according to [1] or [2], wherein the glass article is colored.

[11] The glass article according to

[10] , wherein, when molded into a measurement sample having a thickness of 1 mm, the difference between the maximum and minimum values ​​of transmittance at wavelengths of 400 to 800 nm is more than 10.0%.

[12] The glass article according to [1] or [2], wherein the glass article has a polyhedral shape and has 7 or more faces.

[13] The glass article according to [1] or [2], having at least one pair of two adjacent flat surfaces, the angle between the two flat surfaces being 100 to 170°.

[14] The glass article according to

[13] , having a maximum diameter of 3.0 mm or more.

[15] The glass article according to [1] or [2], having a plate shape and a plate thickness of 0.4 to 3.0 mm.

[16] A glass article having a refractive index nd of 1.60 or more, and having, when molded into a measurement sample with a thickness of 1 mm, a difference between the maximum and minimum transmittance values ​​at wavelengths of 400 to 800 nm of more than 10.0%.

[0009] According to the present invention, a novel glass article can be provided.

[0010] FIG. 10 is a cross-sectional schematic view for explaining a method for measuring the number of fractures.

[0011] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0012] In this specification, "chemically strengthened glass" refers to glass or a glass article after chemical strengthening treatment, and "glass for chemical strengthening" refers to glass or a glass article before chemical strengthening treatment.

[0013] In this specification, the glass composition of chemically strengthened glass is sometimes referred to as the mother glass composition of chemically strengthened glass. In chemically strengthened glass, a compressive stress layer due to ion exchange is usually formed on the glass surface, so the glass composition of the non-ion-exchanged portion is identical to the mother glass composition of chemically strengthened glass. In this specification, the glass composition is expressed in mole percentage based on oxides, and mole % is sometimes simply written as %. In addition, in this specification, the symbol "to" indicating a numerical range is used to mean that the numbers written before and after it are included as the lower and upper limits.

[0014] In the glass composition of this specification, "substantially not contained" means that the components are not contained except for unavoidable impurities contained in raw materials, etc., that is, they are not intentionally contained. Specifically, the content of components other than those described as the glass composition is, for example, preferably less than 0.1 mol%, more preferably 0.08 mol% or less, and even more preferably 0.05 mol% or less.

[0015] In this specification, parameters related to compressive stress are calculated from the stress profile. In this specification, the "stress profile" is a pattern that represents compressive stress values ​​with the depth from the glass surface as a variable. A negative compressive stress value means tensile stress. In this specification, the "stress profile" is measured using a scattered light photoelastic stress meter or a surface stress meter. An example of a scattered light photoelastic stress meter is the SLP-2000 manufactured by Orihara Seisakusho Co., Ltd. An example of a surface stress meter is the FSM-6000LE manufactured by Orihara Seisakusho Co., Ltd. In this specification, the compressive stress layer depth DOL is the depth at which the compressive stress value becomes zero. In this specification, the surface compressive stress CS refers to the compressive stress value at a depth of 0 μm. Li ２ When a glass article containing O is subjected to ion exchange with a salt containing sodium ions, the stress profile can be measured using a scattered light photoelastic stress meter.２ When a glass article containing O is ion-exchanged with a salt containing potassium ions, the stress profile can be measured using a surface stress meter.

[0016] The glass article of the present invention may be embodied in a first embodiment having a compressive stress layer on the surface thereof, or in a second embodiment having no compressive stress layer on the surface thereof. Hereinafter, the first embodiment of the glass article of the present invention and the second embodiment of the glass article of the present invention will be described.

[0017] <Glass Article (First Embodiment)> The first embodiment of the glass article of the present invention has a refractive index nd of 1.60 or more and has a compressive stress layer on the surface. Furthermore, the product of the compressive stress layer depth DOL and the surface compressive stress CS is 18,000 MPa μm or more. Since glass articles can be used in situations where various objects may come into contact or collide, it is preferable that they have excellent strength. According to the first embodiment of the glass article of the present invention, a glass article having a high refractive index and excellent strength can be provided. Furthermore, according to the first embodiment of the glass article of the present invention, a novel glass article can be provided. The mechanism by which the first embodiment of the glass article of the present invention has a high refractive index nd and excellent strength is not necessarily clear, but the inventors speculate as follows. As described above, the first embodiment of the glass article of the present invention has a high refractive index nd of 1.60 or more. Furthermore, the product of the compressive stress layer depth DOL and the surface compressive stress CS is 18,000 MPa or more. When the value of the above product is equal to or greater than a predetermined value, compressive stress acts on the surface, making the surface of the glass article less susceptible to scratches. Furthermore, since compressive stress acts to a predetermined depth, even if the surface of the glass article is scratched, the scratch is less likely to spread, and it is thought that the strength of the glass article is excellent.

[0018] A first embodiment of the glass article of the present invention will now be described.

[0019] [Refractive Index] The refractive index nd of the first embodiment of the glass article of the present invention is 1.60 or more. In this specification, the refractive index nd of the glass article refers to the refractive index of the portion other than the compressive stress layer on the surface. That is, in this specification, the refractive index of the glass article refers to the refractive index at the center of the glass article. In this specification, the refractive index nd of the glass article is the refractive index at the d-line (helium d-line, wavelength 587.6 nm) and is measured by the V-block method described below. First, the glass article is processed into a triangular prism with a side length of 15 mm and a thickness of 2 mm, and the refractometer is measured using a refractometer (Shimadzu Corporation, Kalnew Precision Refractive Index Diameter KPR-3000). In the prism obtained by the above processing, the compressive stress layer on the surface is removed. Furthermore, if it is difficult to process the glass article into a prism of the above size, it may be measured using a method that measures a similar refractive index. For example, if the glass article is small and difficult to process to the above size, the glass article can be processed into a plate with a thickness of 1 mm, and the refractive index can be determined using a glass prism coupler (e.g., Prism Coupler, manufactured by Metricon Co., Ltd.) Alternatively, the refractive index can be determined by irradiating a laser beam onto the surface of the glass article and using Snell's law from the relationship between the angle of incidence and the angle of refraction.

[0020] The refractive index nd of the first embodiment of the glass article of the present invention is preferably 1.65 or more, more preferably more than 1.70, even more preferably 1.72 or more, and may be 1.75 or more, 1.78 or more, or 1.80 or more. The refractive index of the first embodiment of the glass article of the present invention is, for example, 2.20 or less, preferably 2.00 or less.

[0021] [Depth of compressive stress layer DOL] The first embodiment of the glass article of the present invention has a compressive stress layer on the surface. Here, the depth of compressive stress layer DOL is not particularly limited as long as the value of the above product is within the above-mentioned predetermined range, but is preferably 30 μm or more, more preferably 45 μm or more, and even more preferably 50 μm or more. In addition, the depth of compressive stress layer DOL is preferably 200 μm or less, more preferably 150 μm or less, more preferably 100 μm or less, and particularly preferably 80 μm or less.

[0022] [Surface compressive stress CS] The first embodiment of the glass article of the present invention has a compressive stress layer on the surface. Here, the surface compressive stress CS is the value of the compressive stress at a depth of 0 μm. The measurement method is as described above. The surface compressive stress CS is not particularly limited as long as the value of the above product is within the above-mentioned predetermined range, but is preferably 300 MPa or more, more preferably 380 MPa or more, even more preferably 400 MPa or more, even more preferably 450 MPa or more, and particularly preferably 500 MPa or more. Furthermore, the surface compressive stress CS is preferably 1,400 MPa or less, more preferably 1,200 MPa or less, even more preferably 1,000 MPa or less, and most preferably 800 MPa or less.

[0023] In the first embodiment of the glass article of the present invention, as described above, the value of the product of the compressive stress layer depth DOL and the surface compressive stress CS may be 18,000 MPa μm or more, but the value of the product is preferably 20,000 MPa μm or more, more preferably 25,000 MPa μm or more, in terms of higher strength. In addition, the upper limit of the value of the product is not particularly limited, but is preferably 100,000 MPa μm or less, more preferably 80,000 MPa μm or less, even more preferably 60,000 MPa μm or less, and particularly preferably 40,000 MPa μm or less, in terms of the tendency to reduce the number of fractures described later.

[0024] In addition, the first embodiment of the glass article of the present invention is preferably a chemically strengthened glass obtained by chemical strengthening. In the chemically strengthened glass, the compressive stress layer depth DOL and the surface compressive stress CS can be adjusted by the mother glass composition described later and the chemical strengthening conditions.

[0025] [Tensile stress] As described above, the first embodiment of the glass article of the present invention has a compressive stress layer on the surface, and therefore a tensile stress that balances with the stress acting on the compressive stress layer acts inside the glass article. The maximum value of the tensile stress (CT) in the first embodiment of the glass article of the present invention is preferably 200 MPa or less, more preferably 100 MPa or less, and even more preferably 80 MPa or less, in order to make it less likely for the glass to scatter fragments when broken (reducing the number of fractures). The lower limit of the maximum value of the tensile stress is, for example, 5 MPa or more, and is often 10 MPa or more.

[0026] When the first embodiment of the glass article of the present invention has a plate shape, the maximum value of the tensile stress usually acts at the center position in the plate thickness direction.

[0027] The number of fractures, the measurement method of which will be described in detail in the Examples section below, is preferably 50 or less, more preferably 30 or less, even more preferably 10 or less, and particularly preferably 5 or less. The number of fractures means the number of fragments when the glass article breaks.

[0028] [Young's modulus] The Young's modulus of the first embodiment of the glass article of the present invention is preferably 70 GPa or more, more preferably 90 GPa or more, and even more preferably 95 GPa or more. The Young's modulus of the first embodiment of the glass article of the present invention is usually 150 GPa or less, and in many cases 120 GPa or less. The Young's modulus can be measured by the method shown in the Examples section below.

[0029] [Transmittance] When measuring the transmittance of the first embodiment of the glass article of the present invention, the glass article may not have absorption in a specific wavelength range, or may have absorption in a specific wavelength range. That is, the first embodiment of the glass article of the present invention may be colored or may not have coloration. Specifically, when molded into a 1 mm thick measurement sample, the difference between the maximum and minimum transmittance values ​​at wavelengths of 400 to 800 nm (hereinafter also referred to as the "maximum transmittance difference") may be less than 10.0% or more than 10.0%. In this specification, the transmittance at wavelengths of 400 to 800 nm is measured using a spectrophotometer (U-4100 manufactured by Hitachi High-Technologies Corporation) after preparing a mirror-polished 1 mm thick measurement sample. Note that if the measurement sample cannot be prepared from the glass article, a measurement sample of a predetermined thickness may be prepared, and measurements may be performed in the same manner to calculate the transmittance converted to a 1 mm thickness. Note that the Beer-Lambert law is used for the conversion. Hereinafter, glass having the maximum transmittance difference of 10.0% or less will also be referred to as colorless glass, and glass having the maximum transmittance difference of more than 10.0% will also be referred to as colored glass.

[0030] When the first embodiment of the glass article of the present invention is colorless glass, the maximum transmittance difference is preferably 5.0% or less, more preferably 3.0% or less. When the first embodiment of the glass article of the present invention is colorless glass, the maximum transmittance difference is often more than 0.0%.

[0031] When the first embodiment of the glass article of the present invention is a colored glass, the maximum transmittance difference is preferably 13.0% or more, more preferably 15.0% or more. The maximum transmittance difference may be 20.0% or more, 30.0% or more, or even 40.0% or more. When the first embodiment of the glass article of the present invention is a colored glass, the maximum transmittance difference is often 80.0% or less, preferably 70.0% or less, and more preferably 60.0% or less.

[0032] [Composition] The composition of the central portion of the first embodiment of the glass article of the present invention will be described. When the first embodiment of the glass article of the present invention is a chemically strengthened glass, the composition of the central portion corresponds to the mother glass composition.

[0033] In the composition of the center portion of the first embodiment of the glass article of the present invention (preferably the mother glass composition), Li ２ The content of O is preferably 7.0% or more, more preferably 9.0% or more, further preferably 11.0% or more, and particularly preferably 13.0% or more, in mole percent on an oxide basis. ２ The content of O is preferably 25.0% or less, more preferably 23.0% or less. Furthermore, in the composition of the center portion of the first embodiment of the glass article of the present invention (preferably the mother glass composition), Li ２ O, Na ２ O and K ２ The total content of O is preferably 12.0% or more, more preferably 15.0% or more, even more preferably 16.0% or more, particularly preferably 18.0% or more, and most preferably 20.0% or more, in mole percent on an oxide basis. ２ O, Na ２ O and K ２ The total content of O is preferably 35.0% or less, more preferably 30% or less. When the first embodiment of the glass article of the present invention is chemically strengthened glass, the above composition makes it easier for chemical strengthening to proceed and makes it easier to satisfy the value of the above-mentioned product.

[0034] In addition, in the composition of the central portion of the first embodiment of the glass article of the present invention (preferably the mother glass composition), SiO ２ The content of SiO is preferably 10.0% or more, and more preferably 30.0% or more, in mole % on an oxide basis. ２ The content is preferably 70.0% or less.

[0035] The composition of the central portion of the first embodiment of the glass article of the present invention (preferably the mother glass composition) is, in terms of mole percentage based on oxides, SiO ２ 30.0 to 70.0% Al ２ O ３ 0.0~10.0% Li ２ O 7.0-25.0% Na ２ O 0.5 to 10.0% K ２O 0.5 to 10.0% MgO 0.0 to 5.0% CaO 0.0 to 5.0% SrO 0.0 to 5.0% BaO 0.0 to 5.0% ZnO 0.0 to 5.0% TiO ２ 0.0 to 10.0% ZrO ２ 0.0 to 5.0% Nb ２ O ５ 5.0 to 25.0% La ２ O ３ 0.0 to 10.0% SnO ２ 0.0 to 1.0% B ２ O ３ 0.0 to 10.0% Y ２ O ３ The content range of each component is described in more detail below.

[0036] Each component contained in the mother glass composition will be described below. ２ The content expressed as mole percentage based on oxides is expressed as "[SiO ２ ]" may be written as follows.

[0037] SiO ２ is a component that forms the glass network. It also increases chemical durability and reduces the occurrence of cracks when the glass surface is scratched.

[0038] SiO ２ In order to improve chemical durability, the content of SiO is more preferably 40.0% or more, further preferably 45.0% or more, and particularly preferably 48.0% or more. ２ The content is more preferably 65.0% or less, further preferably 60.0% or less, and particularly preferably 58.0% or less.

[0039] Al ２ O ３ is a component that improves the ion exchange performance during chemical strengthening and increases the surface compressive stress after strengthening. ２ O ３The content of Al is more preferably 0.5% or more, and even more preferably 1% or more. On the other hand, there are cases where it is required that crystals do not grow easily during melting, that devitrification defects do not occur easily, and that the yield is likely to be higher, and that the high-temperature viscosity of the glass is reduced to make it easier to melt. From these viewpoints, Al ２ O ３ The Al content is more preferably 8.0% or less, further preferably 5.0% or less, and particularly preferably 2.0% or less. ２ O ３ may not be substantially included.

[0040] SiO ２ and Al ２ O ３ These are all components that stabilize the glass structure. ２ and Al ２ O ３ The total content of SiO is preferably 40.0% or more, and more preferably 50.0% or more. ２ and Al ２ O ３ Both of these tend to increase the melting temperature of the glass. ２ and Al ２ O ３ The total content is preferably 70.0% or less, more preferably 65.0% or less.

[0041] Li ２ O is a component capable of ion exchange and improves the melting property of the glass. ２ By containing O, Li ions on the glass surface are ion-exchanged with external Na ions to be incorporated into the glass, and the incorporated Na ions are then ion-exchanged with external K ions, which makes it easier to obtain a stress profile with a large surface compressive stress and a thick compressive stress layer. ２ As described above, the O content is preferably 7.0% or more, more preferably 9.0% or more, even more preferably 12.0% or more, and particularly preferably 15.0% or more.

[0042] On the other hand, from the viewpoint of reducing the crystal growth rate during glass molding and making it difficult for quality degradation due to devitrification to occur, Li ２ The O content is more preferably 23.0% or less, further preferably 21.0% or less, and particularly preferably 20.0% or less.

[0043] Na ２ O and K ２ O is a component that improves the meltability of the glass and reduces the crystal growth rate during glass molding. It is also preferable to include a small amount of O in order to improve the ion exchange performance.

[0044] Na ２ O is a component that can be ion-exchanged in chemical strengthening treatment using potassium salts, and also a component that reduces the viscosity of glass. ２ The O content is more preferably 1.0% or more, further preferably 2.0% or more, particularly preferably 4.0% or more, and most preferably 5.0% or more.

[0045] K ２ O is a component that suppresses the rise in devitrification temperature to suppress devitrification and also improves ion exchange performance. ２ The O content is more preferably 1.0% or more, further preferably 2.0% or more, and particularly preferably 3.0% or more.

[0046] Li ２ O content, Na ２ O content and K content ２ From the viewpoint of suppressing an increase in the devitrification temperature and reducing the crystal growth rate, the total content of O, R, is preferably 12.0% or more, more preferably 15.0% or more, even more preferably 16.0% or more, particularly preferably 18.0% or more, and most preferably 20.0% or more, as described above. As described above, R is preferably 35.0% or less, more preferably 30.0% or less.

[0047] Li for the above R ２ The ratio of the content of O ([Li ２ O] / ([Li ２ O] + [Na ２ O] + [K ２ O]), hereinafter referred to as “Li ２ O / R２ From the viewpoint of further improving the chemical strengthening properties against compressive stress in the deep layer, Li is more preferably 0.30 or more, and even more preferably 0.40 or more. ２ O / R ２ From the viewpoint of further enhancing chemical resistance, O is more preferably 0.90 or less, further preferably 0.85 or less, and particularly preferably 0.75 or less.

[0048] Na for the above R ２ The ratio of the content of O ([Na ２ O] / ([Li ２ O] + [Na ２ O] + [K ２ O]), hereinafter referred to as “Na ２ O / R ２ From the viewpoint of further improving the chemical strengthening properties against compressive stress in the deep layer, Na is preferably 0.08 or more, more preferably 0.15 or more, and even more preferably 0.20 or more. ２ O / R ２ From the viewpoint of further enhancing chemical resistance, O is preferably 0.60 or less, more preferably 0.50 or less, even more preferably 0.40 or less, and particularly preferably 0.35 or less.

[0049] K for the above R ２ The ratio of the content of O ([K ２ O] / ([Li ２ O] + [Na ２ O] + [K ２ O]), hereinafter referred to as “K ２ O / R ２ From the viewpoint of further improving the electrical resistance of the glass, K is preferably 0.01 or more, more preferably 0.015 or more, even more preferably 0.02 or more, particularly preferably 0.08 or more, and most preferably 0.10 or more. ２ O / R ２ From the viewpoint of further enhancing the chemical strengthening properties against compressive stress near the surface, O is preferably 0.50 or less, more preferably 0.40 or less, and even more preferably 0.30 or less.

[0050] Also, Li ２ O / R ２ O and Na ２ O / R ２O and K ２ O / R ２ From the viewpoint of suppressing an increase in the devitrification temperature, the product with O is more preferably 0.002 or more, further preferably 0.01 or more, and particularly preferably 0.015 or more. Moreover, from the viewpoint of improving chemical resistance, the product is more preferably 0.04 or less.

[0051] Also, Na ２ K content relative to O content ２ The ratio of the content of O ([K ２ O] / [Na ２ O]) is preferably 0.0 to 1.8. ２ O] / [Na ２ [O] is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.4 or more, and particularly preferably 0.5 or more, in that it improves the compressive stress near the surface layer and makes it easier to obtain chemically strengthened glass having a greater bending test strength. ２ O] / [Na ２ From the above viewpoints, the value of [Ratio of the saturation potential] is preferably 1.0 or less, more preferably 0.9 or less, and even more preferably 0.85 or less.

[0052] MgO may be contained to reduce viscosity during dissolution, etc. The MgO content is more preferably 0.05% or more, and even more preferably 0.1% or more, 0.2% or more, 0.9% or more, more than 0.9%, and 1.0% or more, in the following order. On the other hand, in order to easily increase the compressive stress layer during chemical strengthening treatment, the MgO content is more preferably 4.0% or less, even more preferably 3.0% or less, and even more preferably 2.0% or less. By setting the MgO content to 4.0% or less, acid resistance can be improved. MgO does not have to be substantially contained.

[0053] CaO is a component that improves the meltability of glass and may be contained. When CaO is contained, the content of CaO is more preferably 0.1% or more, and even more preferably 0.15% or more. On the other hand, in terms of easily increasing the compressive stress value during chemical strengthening treatment, the content of CaO is more preferably 2.0% or less, even more preferably 1.0% or less, particularly preferably 0.8% or less, and most preferably 0.5% or less. CaO may not be substantially contained.

[0054] SrO is a component that improves the meltability of glass and may be contained. When SrO is contained, the content of SrO is more preferably 0.1% or more, even more preferably 0.15% or more, and particularly preferably 0.5% or more. In order to make it easier to increase the compressive stress value during chemical strengthening treatment, the content of SrO is more preferably 3.0% or less, even more preferably 2.0% or less, particularly preferably 1.0% or less, and most preferably 0.5% or less. SrO may not be substantially contained.

[0055] BaO is a component that improves the meltability of glass and may be contained. When BaO is contained, the content is preferably 0.1% or more, more preferably 0.15% or more, and even more preferably 0.5% or more. In order to facilitate increasing the compressive stress value during chemical strengthening treatment, the content of BaO is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 2.0% or less, particularly preferably 1.0% or less, and most preferably 0.5% or less. BaO may not be substantially contained.

[0056] ZnO is a component that improves the meltability of glass and may be contained. When ZnO is contained, the content of ZnO is more preferably 0.1% or more, even more preferably 0.15% or more, and particularly preferably 0.5% or more. In order to make it easier to increase the compressive stress value during chemical strengthening treatment, the content of ZnO is more preferably 3.0% or less, even more preferably 2.0% or less, particularly preferably 1.0% or less, and most preferably 0.5% or less. ZnO may not be substantially contained.

[0057] TiO ２ is a component that is highly effective in suppressing solarization of glass and may be contained. ２ When TiO is contained, the content is preferably 0.02% or more, more preferably 0.03% or more, even more preferably 0.04% or more, particularly preferably 0.05% or more, and most preferably 0.06% or more. On the other hand, from the viewpoint of preventing the occurrence of devitrification and deterioration of the quality of the chemically strengthened glass, TiO ２ The content of Ti is preferably 5.0% or less, more preferably 3.0% or less, even more preferably 1.0% or less, particularly preferably 0.25% or less, and most preferably 0.15% or less. ２ O may not be substantially contained.

[0058] ZrO ２ is a component that makes it easier to increase the surface compressive stress of chemically strengthened glass. ２ The content of ZrO is more preferably more than 0%, and further preferably 0.1% or more, 0.15% or more, 0.2% or more, 0.25% or more, 0.3% or more, and 0.4% or more in the following order. On the other hand, in terms of suppressing the occurrence of devitrification defects and making it easier to increase the compressive stress value during chemical strengthening treatment, ZrO ２ The content is more preferably 4.0% or less, further preferably 3.5% or less, and particularly preferably 3.2% or less.

[0059] B ２ O ３ reduces the brittleness of the glass and improves the crack resistance, or improves the meltability of the glass. ２ O３ B when containing ２ O ３ The content of B is more preferably 1.0% or more, further preferably 2.0% or more, and particularly preferably 4.0% or more. ２ O ３ The content of is more preferably 8.0% or less, further preferably 6.0% or less, particularly preferably 5.0% or less. From the viewpoint of preventing the occurrence of striae during melting, it is also preferable that it is not substantially contained.

[0060] Y ２ O ３ is a component that makes it easier to increase the surface compressive stress of chemically strengthened glass while slowing down the crystal growth rate. ２ O ３ When Y is contained ２ O ３ The content of Y is more preferably 0.1% or more, and further preferably 0.5% or more. On the other hand, Y is preferred because it is easy to increase the compressive stress layer during chemical strengthening treatment. ２ O ３ The content of Y is more preferably 2.0% or less. ２ O ３ may not be substantially included.

[0061] Nb ２ O ５ is one of the components that can easily increase the refractive index. ２ O ５ The Nb content is more preferably 8.0% or more, further preferably 10.0% or more, and particularly preferably 12.0% or more. ２ O ５ The content is more preferably 22.0% or less, and further preferably 20.0% or less.

[0062] La ２ O ３ is not required, but Y ２ O ３ It can be contained for the same reasons as above. ２ O ３is preferably 0.1% or more, more preferably 0.2% or more, further preferably 0.5% or more, particularly preferably 0.8% or more. On the other hand, if the content is too high, it becomes difficult to increase the compressive stress layer during chemical strengthening treatment. ２ O ３ is preferably 5.0% or less, more preferably 4.0% or less. ２ O ３ may not be substantially included.

[0063] Ta ２ O ５ , Gd ２ O ３ , and CeO ２ is a component that has the effect of suppressing solarization of the glass and improving meltability, and may be contained. When these components are contained, the content of each is preferably 0.03% or more, more preferably 0.1% or more, even more preferably 0.5% or more, particularly preferably 0.8% or more, and most preferably 1.0% or more. On the other hand, it is preferably 3.0% or less, more preferably 2.0% or less, and even more preferably 1.0% or less.

[0064] Fe ２ O ３ Since Fe absorbs heat rays, it has the effect of improving the meltability of glass, and is preferably contained when mass-producing glass using a large melting furnace. In this case, the content is preferably 0.002% or more, more preferably 0.005% or more, even more preferably 0.007% or more, and particularly preferably 0.01% or more, expressed in mass% on an oxide basis. On the other hand, Fe ２ O ３ Since an excessive content of causes coloration, from the viewpoint of enhancing the transparency of the glass, the content thereof, expressed as mass% on an oxide basis, is preferably 0.3% or less, more preferably 0.04% or less, even more preferably 0.025% or less, and particularly preferably 0.015% or less.

[0065] Furthermore, other coloring components may be added to the extent that the desired chemical strengthening properties are not impaired. Addition of other coloring components can satisfy the above-mentioned requirements for colored glass. Examples of other coloring components include CoO, Co３ O ４ , MnO ２ , NiO, Cu ２ O, CuO, Cr ２ O ３ , V ２ O ５ , SnO ２ , Bi ２ O ３ , SeO ２ , Er ２ O ３ , Nd ２ O ３ Suitable examples include the above. The value of the above-mentioned maximum transmittance difference can be adjusted by adjusting the type and content of the other coloring components. The total content of the coloring components is, in terms of external percentage relative to the mother glass composition, preferably 0.02% or more, more preferably 0.05% or more, even more preferably 0.07% or more, and may even be 0.1% or more. Furthermore, the total content of the coloring components is, in terms of external percentage relative to the mother glass composition, preferably 1.0% or less, more preferably 0.5% or less.

[0066] SO is used as a fining agent when melting glass. ３ , chloride, fluoride, etc. may be contained as appropriate. ２ O ３ It is preferable that Sb is not contained. ２ O ３ When it is contained, it is preferably 0.3% or less, more preferably 0.1% or less, and most preferably not contained.

[0067] [Shape] The shape of the first embodiment of the glass article of the present invention is not particularly limited. For example, the first embodiment of the glass article of the present invention may have a plate-like shape. When the first embodiment of the glass article of the present invention has a plate-like shape, the plate thickness may be 0.1 mm or more, preferably 0.2 mm or more, and more preferably 0.4 mm or more. In addition, the plate thickness may be, for example, 10.0 mm or less, preferably 5.0 mm or less, and more preferably 3.0 mm or less.

[0068] Furthermore, examples of the shape of the glass article according to the first embodiment of the present invention include a polyhedron. In this specification, the term "polyhedron" refers not only to a shape consisting of only flat surfaces, but also to a shape having curved surfaces on some of the sides or vertices of a polyhedron consisting of only flat surfaces. More specifically, in a polyhedron, the length l of the shortest side of the face with the smallest area is ｍｉｎ For a radius of curvature of 0.2 x l ｍｉｎ The polyhedral shape also includes shapes having the following curved surfaces. For example, spherical and cylindrical shapes are not included in the polyhedral shape, and a shape obtained by R-chamfering each side of a 1 cm cube with a radius of 3 mm is not included in the polyhedral shape. On the other hand, a shape obtained by R-chamfering each side of a 1 cm cube with a radius of 1.5 mm is included in the polyhedral shape. In this specification, shapes in which cylindrical holes are formed in the above polyhedral shapes are also included in the polyhedral shape.

[0069] When the first embodiment of the glass article of the present invention has a polyhedral shape, it is also preferable that the number of faces is 7 or more. When the first embodiment of the glass article of the present invention has a polyhedral shape, the number of faces is preferably 8 or more, and may be 10 or more, 16 or more, 24 or more, or even 50 or more. There is no particular upper limit on the number of faces, and it may be, for example, 200 or less, and is often 150 or less.

[0070] Furthermore, the first embodiment of the glass article of the present invention preferably has at least one pair of two adjacent planes, where the angle between the two planes is 100 to 170°. For example, a pair of two planes that satisfies the above requirement is a regular dodecahedron, since the angle between two adjacent regular pentagons that constitute the dodecahedron is approximately 116.6°. Furthermore, adjacent planes in gemstone cuts (e.g., so-called brilliant cuts) often satisfy the above requirement. Furthermore, it is also preferable that the first embodiment of the glass article of the present invention satisfies the above requirement and has a polyhedral shape. Note that when the first embodiment of the glass article of the present invention has a polyhedral shape and has curved edges or other portions, the term "adjacent planes" is interpreted as the planes closest to each other.

[0071] The first embodiment of the glass article of the present invention may have a shape having a curved surface. The shape having a curved surface is not particularly limited, and examples thereof include a spherical shape, a cylindrical shape, an ellipsoidal shape, a conical shape, a truncated conical shape, a torus shape, a shape in which the sides of the above-mentioned polyhedral shapes are rounded to a length of a predetermined radius or more, and a shape that is a combination of these shapes.

[0072] In the first embodiment of the glass article of the present invention, the maximum diameter is preferably 1.0 mm or more, more preferably 2.0 mm or more, and even more preferably 3.0 mm or more. In this specification, the maximum diameter refers to the longest distance between two parallel planes that contact the glass article. Furthermore, it is also preferable that the shape of the first embodiment of the glass article of the present invention satisfies the requirements for the pair of two adjacent planes and that the maximum diameter is 1.0 mm or more (more preferably 2.0 mm or more, and even more preferably 3.0 mm or more). Furthermore, the first embodiment of the glass article of the present invention may have a polyhedral shape.

[0073] <Manufacturing Method> A first embodiment of the glass article of the present invention is obtained, for example, by subjecting chemically strengthened glass having a desired shape to a chemical strengthening treatment. The chemical strengthening treatment can be performed by a known method. The chemical strengthening treatment is performed, for example, by contacting the chemically strengthened glass with a molten salt of a metal salt (e.g., potassium nitrate) containing a metal ion with a large ionic radius (typically, K ion). The contact between the chemically strengthened glass and the molten salt of the metal salt is performed, for example, by immersing the chemically strengthened glass in the molten salt of the metal salt. The contact between the chemically strengthened glass and the molten salt of the metal salt causes metal ions with a small ionic radius (typically, Na ions or Li ions) in the chemically strengthened glass to be replaced with metal ions with a large ionic radius (typically, K ions for Na ions, and Na ions or K ions for Li ions).

[0074] Chemical strengthening, i.e., ion exchange treatment, can be performed, for example, by immersing the glass for chemical strengthening in a molten salt such as potassium nitrate heated to 350 to 500° C. for more than 0.5 hours and not more than 500 hours. The heating temperature of the molten salt is preferably 375° C. or higher and 450° C. or lower. The immersion time of the glass for chemical strengthening in the molten salt is preferably 1 hour or longer and preferably 200 hours or shorter, more preferably 50 hours or shorter.

[0075] Examples of metal salts contained in the molten salt for chemical strengthening treatment include nitrates, sulfates, carbonates, and chlorides. Nitrates include lithium nitrate, sodium nitrate, potassium nitrate, cesium nitrate, and silver nitrate. Sulfates include lithium sulfate, sodium sulfate, potassium sulfate, cesium sulfate, and silver sulfate. Carbonates include lithium carbonate, sodium carbonate, and potassium carbonate. Chlorides include lithium chloride, sodium chloride, potassium chloride, cesium chloride, and silver chloride. These metal salts may be used alone or in combination. The lithium content in the metal salt is preferably 4,000 ppm by mass or less, more preferably 1,000 ppm by mass or less, and even more preferably 100 ppm by mass or less, relative to the total mass of the molten salt.

[0076] The stress profile can be adjusted by the treatment conditions of the chemical strengthening treatment. Specifically, the compressive stress layer depth DOL and the surface compressive stress CS can be controlled. More specifically, the treatment conditions of the chemical strengthening treatment include the type and composition of the molten salt used in the chemical strengthening treatment, the temperature of the molten salt, and the contact time with the molten salt, and the like. The parameters can also be adjusted by the composition of the chemically strengthened glass used in the chemical strengthening treatment. The parameters can also be adjusted by adjusting the lithium content in the metal salt.

[0077] The chemical strengthening treatment may be carried out only once, or may be carried out a plurality of times under two or more different conditions (multi-stage strengthening).

[0078] <Uses> The use of the first embodiment of the glass article of the present invention is not particularly limited, but includes decorative applications. That is, the first embodiment of the glass article of the present invention is preferably a decorative glass article. Examples of decorative glass articles include components constituting accessories such as rings, bracelets, anklets, necklaces, pendants, earrings, pierced earrings, brooches, and cufflinks, as well as stone materials used in the above accessories. Examples of decorative glass articles also include handles such as chandeliers and doorknobs, household items such as tableware, glasses, and wind chimes. Examples also include lenses and covers for diffusing light.

[0079] Other uses of the first embodiment of the glass article of the present invention include cover glass. For example, it is useful as cover glass for mobile devices such as mobile phones, smartphones, personal digital assistants (PDAs), and tablet terminals. Furthermore, it is useful as cover glass for non-portable display devices such as televisions (TVs), personal computers (PCs), and touch panels, as cover glass for the surface of solar cell modules, elevator walls, walls (full-surface displays) of buildings such as houses and buildings, building materials such as window glass, tabletops, and interiors of automobiles and airplanes. It is also useful as cover glass for the above-mentioned articles. Furthermore, it can be applied to applications such as housings having curved shapes by bending and bending forming.

[0080] Furthermore, since the first embodiment of the glass article of the present invention has a high refractive index, it is also preferably used as a light-guiding member. That is, the first embodiment of the glass article of the present invention is also preferably a glass article for a light-guiding member. Examples of light-guiding members include light-guiding plates and light-guiding fibers. Known shapes can be adopted for the light-guiding member. The light-guiding member can be used, for example, in virtual reality devices (VR devices), augmented reality devices (AR devices), mixed reality devices (MR devices), etc.

[0081] The first embodiment of the glass article of the present invention has a high refractive index and excellent strength, making it suitable for use in the above-mentioned applications. In particular, because of its excellent strength, the first embodiment of the glass article of the present invention is less likely to break. Furthermore, because of its high refractive index, it has excellent design properties.

[0082] <Glass Article (Second Embodiment)> A second embodiment of the glass article of the present invention has a refractive index nd of 1.60 or more, and when molded into a measurement sample with a thickness of 1 mm, the difference between the maximum and minimum transmittance at wavelengths of 400 to 800 nm exceeds 10.0%. Note that the second embodiment of the glass article of the present invention does not have a compressive stress layer on the surface. According to the second embodiment of the glass article of the present invention, a novel glass article can be provided. The second embodiment of the glass article of the present invention will be described below.

[0083] [Refractive Index] The refractive index nd of the second embodiment of the glass article of the present invention is 1.60 or more. The refractive index of the second embodiment of the glass article of the present invention is preferably 1.65 or more, more preferably more than 1.70, even more preferably 1.72 or more, and may be 1.75 or more, 1.78 or more, or 1.80 or more. The refractive index of the second embodiment of the glass article of the present invention is, for example, 2.20 or less, preferably 2.00 or less. The method for measuring the refractive index is the same as that of the first embodiment of the glass article of the present invention, and therefore, description thereof will be omitted.

[0084] [Transmittance] In the second embodiment of the glass article of the present invention, when molded into a measurement sample with a thickness of 1 mm, the difference between the maximum and minimum transmittance values ​​at wavelengths of 400 to 800 nm (maximum transmittance difference) exceeds 10.0%. When the transmittance of the second embodiment of the glass article of the present invention is measured, it has absorption in a specific wavelength range. In other words, the second embodiment of the glass article of the present invention is a colored glass having coloration. The method for measuring transmittance is the same as that for the first embodiment of the glass article of the present invention, and therefore description thereof will be omitted. The preferred range of the maximum transmittance difference is the same as that when the first embodiment of the glass article of the present invention is colored glass.

[0085] The second embodiment of the glass article of the present invention has the same Young's modulus, composition, and shape as the first embodiment of the glass article of the present invention. The second embodiment of the glass article of the present invention has the same uses as the first embodiment of the glass article of the present invention. The second embodiment of the glass article of the present invention is a colored glass and has a high refractive index, resulting in excellent design properties.

[0086] The present invention will be described in more detail below based on examples. The materials, amounts used, ratios, treatment details, and treatment procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below. Examples 1 to 13 and 17 to 20 are examples, and Examples 14 to 16 are comparative examples.

[0087] <Preparation of Chemically Tempered Glass> First, glass materials A and B were prepared by melting glass raw materials in a platinum crucible to obtain the glass compositions shown in Table 1, expressed in mole percentages based on oxides. Specifically, commonly used glass raw materials, such as oxides, hydroxides, carbonates, or nitrates, were appropriately selected and weighed to obtain 1,000 g of glass. The mixed raw materials were then placed in a platinum crucible and placed in a resistance-heated electric furnace at 1,200 to 1,500 °C. The mixture was melted for approximately two hours, degassed, and homogenized to obtain molten glass. The resulting molten glass was poured into a mold and held at a temperature of glass transition point + 50 °C for one hour. It was then cooled to room temperature at a rate of 0.5 °C / min to obtain a glass block. The resulting glass block was then cut and ground to obtain a plate glass. Sample pieces for measuring Young's modulus were also cut from the glass block. Both surfaces of the obtained plate glass were mirror-finished to finally obtain a plate glass (glass for chemical strengthening) having a length of 50 mm and a width of 50 mm. The plate thickness of the glass for chemical strengthening was adjusted as shown in Table 2 below.

[0088]

[0089] Each of the chemically strengthened glasses obtained by the above procedure was subjected to a chemical strengthening treatment under the conditions shown in Table 2 below, to obtain chemically strengthened glasses of Examples 1 to 16. The Li concentration in the molten salt used in the chemical strengthening treatment was measured in advance. The Li concentration is also shown in Table 2 below.

[0090] <Measurement of stress profile> The stress profile of the chemically strengthened glass was obtained by the method described above. For the chemically strengthened glasses of Examples 1 to 14 and 16, the stress profile was obtained using the scattered light photoelastic stress meter SLP-2000 manufactured by Orihara Seisakusho Co., Ltd. For the chemically strengthened glass of Example 15, a stress profile was obtained using a surface stress meter FSM-6000LE manufactured by Orihara Seisakusho Co., Ltd.

[0091] <Measurement of refractive index> The refractive index of the glass for chemical strengthening was measured by the method described above. The refractive index can also be determined from the angle of the laser trajectory using a scattered light photoelastic stress meter (SLP-2000). The measurement wavelength was 518 nm, and the refractive index at the center of the glass before and after chemical strengthening was measured. It was confirmed that the measured refractive index at the center of the glass did not change.

[0092] <Measurement of Young's Modulus> In the procedure for obtaining each of the above glass materials, the Young's modulus of the glass for chemical strengthening was measured using a cut sample piece. Specifically, the sample piece was used to perform measurement in accordance with JIS R 1602 by an ultrasonic pulse method. The Young's modulus of the glass for chemical strengthening corresponds to the Young's modulus of the chemically strengthened glass (glass article). The Young's modulus of the chemically strengthened glass (glass article) was measured using the same method as the sample piece, and was the same as the value measured using the sample piece. Therefore, in the tables below, the Young's modulus of the chemically strengthened glass (glass article) is omitted.

[0093] <Measurement of Number of Fractures> The number of fractures of chemically strengthened glass was measured using the following procedure. The method for measuring the number of fractures will be described with reference to the drawings. FIG. 1 is a cross-sectional schematic diagram illustrating the method for measuring the number of fractures. In FIG. 1, chemically strengthened glass 200 is placed on a sample stage 300. An indenter 110 is held so that a tip 111 of the indenter 110 contacts a surface 210 of the chemically strengthened glass 200. The indenter 110 is attached to a testing machine (not shown) capable of moving the indenter 110 at a predetermined load and speed in the normal direction of the surface 210 of the chemically strengthened glass 200. The indenter 110 was made of diamond, and the facing angle of the tip 111 was 90°. The testing machine to which the indenter 110 was attached was a small desktop testing machine EZ-SX manufactured by Shimadzu Corporation. The thickness of the chemically strengthened glass 200 was 0.8 mm.

[0094] The number of fractures was measured according to the following procedure. First, from the state shown in FIG. 1, the indenter 110 was pressed into the surface 210 of the chemically strengthened glass 200 at a predetermined speed of 60 μm / s, and the indenter load was held at 1 kgf (approximately 9.8 N) for 15 seconds. The indenter load was then removed and the chemically strengthened glass 200 was observed. If the observation of the chemically strengthened glass 200 showed that the chemically strengthened glass 200 was not cracked, the indenter 110 was pressed into the chemically strengthened glass 200 and the chemically strengthened glass 200 was observed repeatedly while increasing the indentation load by 1 kgf (approximately 9.8 N) until a crack occurred in the chemically strengthened glass 200. The number of fragments of the chemically strengthened glass 200 at the time when a crack occurred in the chemically strengthened glass 200 was counted, and this number was taken as the number of fractures.

[0095] <Evaluation of bending strength> The bending strength of chemically strengthened glass was measured by a four-point bending method. Specifically, the bending strength was evaluated by the following method. First, a 100 mm x 50 mm strip-shaped test piece was prepared. Next, a four-point bending test was performed on the above test piece under the conditions of a distance between the external supports of the support tool of 30 mm, a distance between the internal supports of 10 mm, and a crosshead speed of 5.0 mm / min. The four-point bending test was performed under the above conditions, and the test force at which the test piece broke was recorded. The four-point bending test was performed on 20 test pieces, and the arithmetic mean value of the test forces at which the test pieces broke was used as the bending strength of the chemically strengthened glass. Each test piece was processed to 100 mm x 50 mm, and then C-chamfered using an 800-grit grinding wheel (manufactured by Tokyo Diamond Tools Mfg. Co., Ltd.) before being subjected to the above four-point bending test.

[0096] <Results> Table 2 shows the chemical strengthening treatment conditions for each chemically strengthened glass and the results of each of the above measurements. In Table 2, the Li content indicates the content of Li metal relative to the total amount of molten salt. In Table 2, "CS" refers to the surface compressive stress CS. Furthermore, "DOL" refers to the compressive stress layer depth DOL. Furthermore, "CT" refers to the tensile stress. Furthermore, "CS × DOL" is the product of the compressive stress layer depth DOL and the surface compressive stress CS. In Table 2, 4PB strength indicates the bending strength measured by the above-mentioned method measured using the four-point bending method.

[0097]

[0098] From the results shown in Table 2, it was confirmed that the chemically strengthened glasses (glass articles) of Examples 1 to 13, in which the product of the compressive stress layer depth DOL and the surface compressive stress CS was 18,000 or more, exhibited higher strength than the chemically strengthened glasses (glass articles) of Examples 14 to 16, in which the product was less than 18,000. Furthermore, from a comparison between Examples 5 to 8 and Examples 1 to 4, it was confirmed that when the product was 40,000 or less, the number of fractures tended to be reduced.

[0099] <Preparation of Colored Glass> The coloring components shown in Table 3 below were further added to the composition of the above-described glass material A to obtain the colored glasses of Examples 17 to 20. Each of the above-described colored glasses was processed to a plate thickness of 1 mm and subjected to the same chemical strengthening treatment as in Example 1 above. The transmittance of the obtained chemically strengthened glass of each example was measured using the method described above, and the maximum and minimum transmittance values ​​in the wavelength range of 400 to 800 nm were obtained. The refractive index of the obtained chemically strengthened glass of each example was also measured using the method described above. The results are shown in Table 3. Table 3 also lists the color of each chemically strengthened glass when white light is transmitted through it.

[0100]

[0101] From the results shown in Table 3, the chemically strengthened glass (glass article) of Example 1 had a maximum transmittance difference of 10.0% or less and was colorless glass. On the other hand, the chemically strengthened glasses (glass articles) of Examples 17 to 20 had a maximum transmittance difference of more than 10.0% and were colored glass. When the chemically strengthened glasses of Examples 17 to 20 were subjected to the same measurements as those of the chemically strengthened glass of Example 1, similar results were obtained. That is, it was confirmed that the value of the product of the compressive stress layer depth DOL and the surface compressive stress CS was 18,000 or more, indicating high strength.

[0102] The above-described transmittance was measured for the colored glass (the second embodiment) before chemically strengthening the chemically strengthened glasses (glass articles) of Examples 17 to 20, and the maximum and minimum transmittance values ​​at wavelengths of 400 to 800 nm were obtained. The values ​​obtained were similar to those shown in Table 3. The refractive indexes were also similar.

[0103] The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2024-113385 filed on July 16, 2024 are hereby incorporated by reference as the disclosure of the specification of the present invention.

[0104] 110 indenter 111 tip 200 chemically strengthened glass 210 surface 300 sample stage

Claims

1. A glass article having a refractive index nd of 1.60 or more and a compressive stress layer on its surface, wherein the product of the compressive stress layer depth DOL and the surface compressive stress CS is 18,000 MPa μm or more.

2. The glass article according to claim 1, wherein the surface compressive stress CS is 400 MPa or more.

3. A glass article according to claim 1 or 2, wherein the compressive stress layer depth DOL is 30 μm or more.

4. A glass article according to claim 1 or 2, having a refractive index nd greater than 1.

70.

5. In the composition of the central part, Li ２ 3. The glass article according to claim 1, wherein the O content is 7.0% or more in mole percent on an oxide basis.

6. In the composition of the central part, Li ２ O, Na ２ O and K ２ 3. The glass article according to claim 1, wherein the total content of O is 12.0% or more in mole percent on an oxide basis.

7. The composition of the central part is SiO ２ 3. The glass article according to claim 1, wherein the content of is 10.0% or more in mole percent on an oxide basis.

8. A glass article according to claim 1 or 2, having a Young's modulus of 90 GPa or more.

9. A glass article according to claim 1 or 2, in which, when molded into a measurement sample having a thickness of 1 mm, the difference between the maximum and minimum transmittance values ​​in the wavelength range of 400 to 800 nm is 10.0% or less.

10. A glass article according to claim 1 or 2, having a coloring.

11. The glass article according to claim 10, which, when molded into a measurement sample with a thickness of 1 mm, has a difference between the maximum and minimum transmittance values ​​in the wavelength range of 400 to 800 nm of more than 10.0%.

12. The glass article according to claim 1 or 2, which has a polyhedral shape and has seven or more faces.

13. A glass article according to claim 1 or 2, which has at least one pair of two adjacent flat surfaces, the angle between the two flat surfaces being 100 to 170 degrees.

14. The glass article according to claim 13, having a maximum diameter of 3.0 mm or more.

15. The glass article according to claim 1 or 2, which has a plate shape and a plate thickness of 0.4 to 3.0 mm.

16. A glass article having a refractive index nd of 1.60 or more, and when molded into a measurement sample with a thickness of 1 mm, the difference between the maximum and minimum transmittance values ​​in the wavelength range of 400 to 800 nm exceeds 10.0%.

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