Glass, and method for identifying glass

Abstract

The purpose of the present invention is to provide: a glass that can achieve efficient recycling; and a method for identifying a glass. The glass has two main surfaces that face each other, contains SnO2, and contains one or more components selected from the group consisting of Nb2O5, WO3, Bi2O3, CeO2, Sm2O3, Eu2O3, and Tb2O3 in a total amount of 0.001 to 2% in mol% in terms of oxide contents, wherein, with respect to average SnO2 concentrations, in mol% in terms of oxide contents, in regions extending from the respective two main surfaces to a depth of 1 μm , when a larger average SnO2 concentration is defined as [SnO2B] and a smaller average SnO2 concentration is defined as [SnO2T], the formula: 10 × [SnO2T] < [SnO2B] is satisfied. The glass satisfies a specified composition range.

Description

Glass and glass identification method

[0001] The present invention relates to glass and a method for identifying glass.

[0002] In recent years, there has been an increasing demand for the recycling of glass products from the viewpoints of resource circulation and greenhouse gas reduction. However, currently, most discarded glass products and some of the defective glass generated in the manufacturing process are discarded without being recycled.

[0003] One of the reasons why many glass products are discarded without being recycled is the difficulty of recycling them: there are glass products on the market with various compositions manufactured by various manufacturers, and it is extremely difficult to efficiently identify the desired glass from among them.

[0004] Patent Document 1 discloses an apparatus for analyzing the purity of waste glass, in which a sample is taken from a waste glass stream that has been processed by sampling, and the sample is passed through a free-falling track, foreign particles are blown off and removed, and the weight of each group of detected foreign non-ferrous metal particles and opaque foreign particles is measured.

[0005] Japanese Patent Application Publication No. 10-227786

[0006] Since glass has different physical properties such as optical properties, specific gravity, and temperature characteristics depending on the composition, if glass products with different compositions are mixed together during the recycling of glass products, it will lead to a decrease in the quality of the glass products obtained by recycling. Therefore, in the recycling of glass products, it is important to efficiently identify the target glass products.

[0007] Therefore, an object of the present invention is to provide glass and a method for identifying glass that can be efficiently recycled.

[0008] The present invention provides a glass having the following configuration and a method for identifying the glass: 1. A glass having two opposing main surfaces, ２ Contains, in mole percent on an oxide basis, Nb ２ O ５ , W.O. ３ , Bi ２O ３ , CeO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ The average SnO content in a range of 1 μm deep from each of the two main surfaces is, expressed as mole % on an oxide basis, 0.001 to 1% in total of one or more components selected from the group consisting of ２ Concentration: The larger average SnO ２ The concentration is [SnO ２Ｂ ], the smaller average SnO ２ The concentration is [SnO ２Ｔ ], 10 × [SnO ２Ｔ ]<[SnO ２Ｂ ] and a glass that satisfies at least one of the following formulas (1a) to (7a): (1a) 0.01×[SnO ２Ｂ ]<[Nb ２ O ５ ]<3×[SnO ２Ｂ ] (2a) 0.01×[SnO ２Ｂ ]<[WO ３ ]<3×[SnO ２Ｂ ] (3a) 0.01×[SnO ２Ｂ ]<[Bi ２ O ３ ]<1.5×[SnO ２Ｂ ] (4a)0.01×[SnO ２Ｂ ]<[CeO ２ ]<1.5×[SnO ２Ｂ ] (5a) 0.01×[SnO ２Ｂ ]<[Sm ２ O ３ ]<2.5×[SnO ２Ｂ ] (6a)0.01×[SnO ２Ｂ ]<[Eu ２ O ３ ]<2.5×[SnO ２Ｂ ] (7a) 0.01×[SnO ２Ｂ ]<[Tb ２ O ３ ]<2.5×[SnO ２Ｂ ] Nb ２ O ５ , W.O. ３, Bi ２ O ３ , CeO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ In the above, [ ] indicates the content of the component in parentheses in mole percent based on oxide. 2. TiO ２ 3. The glass according to 1 above, containing, in mole percent on an oxide basis, 0.001 to 0.1% of Fe. ２ O ３ 4. The glass according to 1 above, containing, in mole percent on an oxide basis, 0.001 to 0.1% of Fe. ２ O ３ 5. The glass according to any one of 1 to 4 above, which satisfies any one of the following formulae (1b) to (3b): (1b) [Sm ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ] (2b) [Eu ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ] (3b) [Tb ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ] Fe ２ O ３ , TiO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ In the above formula, [ ] indicates the content of the component in parentheses in mole percent based on oxide. 6. The area of ​​each of the two main surfaces is 0.5 cm ２ 7. The glass according to any one of 1 to 5 above, wherein the content is, in mole percent based on oxides, SiO ２ 55-75% B ２ O３ 0 to 10%, Al ２ O ３ 0 to 20%, Na ２ 7. The glass according to any one of 1 to 6 above, containing 3 to 18% of O. 8. In mol % on an oxide basis, Li ２ The glass according to any one of 1 to 7 above, containing 0.1 to 15% O. 9. A method for identifying glass, comprising the following steps (1c) and (2c): (1c) irradiating test light onto each of two opposing main surfaces of a glass, to obtain fluorescence of a detectable intensity; and (2c) determining the chromaticity of the fluorescence obtained in step (1c) by using θ as defined below. Ｂ and θ Ｔ Absolute value of the difference between |θ Ｂ－ θ Ｔ Evaluate whether θ is 5 degrees or more. Ｂ is a value that satisfies the following formulas (1) and (2) for one of the main surfaces, and θ Ｔ is a value that satisfies the following formulas (3) and (4) for the other main surface. ＊ a ＊ b ＊ The chromaticity of the fluorescence in the color system is a ＊ Ｂ , b ＊ Ｂ In the following formulas (3) and (4), L of the other main surface ＊ a ＊ b ＊ The chromaticity of the fluorescence in the color system is a ＊ Ｔ , b ＊ Ｔ Let sinθ Ｂ = b ＊ Ｂ / (a ＊ Ｂ ２ +b ＊ Ｂ ２ ) ０．５ ...Formula (1) cosθ Ｂ = a ＊ Ｂ / (a ＊ Ｂ ２ +b ＊Ｂ ２ ) ０．５ ...Equation (2) sin θ Ｔ = b ＊ Ｔ / (a ＊ Ｔ ２ +b ＊ Ｔ ２ ) ０．５ ...Formula (3) cosθ Ｔ = a ＊ Ｔ / (a ＊ Ｔ ２ +b ＊ Ｔ ２ ) ０．５ ...Formula (4)

[0009] The glass of the present invention contains a specific identifying element, and the content of the identifying element and the amount of SnO on the glass surface are ２ The content of each of these has a specific relationship, and they can be efficiently identified by irradiating them with an inspection light.

[0010] The glass identification method of the present invention involves irradiating a glass having two opposing principal surfaces with inspection light, detecting the fluorescence obtained on each of the principal surfaces, and setting the chromaticity of the fluorescence on both principal surfaces to a specific range, thereby making it possible to efficiently identify the target glass.

[0011] FIG. 1 is a schematic diagram for explaining the glass identifying method of the present embodiment.

[0012] The present inventors have found that by adding an identifying element to a target glass, the target glass can be efficiently identified from a group of glasses having a variety of compositions. Furthermore, the identifying element all emits characteristic fluorescence, and in particular, the identifying element is SnO, which inevitably penetrates into the glass surface during production by the float method. ２ The present inventors have found that the relationship between the amount of the fluorine-containing compound and the amount of the identifying element is important in the above-mentioned identification, and have completed the present invention based on this finding.

[0013] The present invention will be described in detail below, but the present invention is not limited to the following embodiments and can be modified as desired without departing from the spirit of the present invention. Furthermore, the term "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower and upper limits.

[0014] In this specification, unless otherwise specified, the glass composition (content of each component) is expressed in mole percentage on an oxide basis, and mole % is simply represented as "%".

[0015] <Glass> The glass according to an embodiment of the present invention (hereinafter also referred to as the present glass) has two opposing main surfaces. By providing the two opposing main surfaces, it is possible to detect fluorescence obtained by irradiating the glass with inspection light from each of the two main surfaces, and identify the target glass.

[0016] The inspection light is not particularly limited as long as it generates fluorescence when irradiated on the identifying element contained in the glass, and examples include high-pressure mercury lamps, low-pressure mercury lamps, high-pressure sodium lamps, metal halide lamps, halogen lamps, xenon lamps, carbon arc lamps, fluorescent lamps, lasers, LEDs, and organic electroluminescence (EL). In order to control the wavelength of the inspection light, it is used in combination with a color filter or a diffraction grating as necessary. The inspection light is also called excitation light.

[0017] Fluorescence can be measured using a phototube, photomultiplier, photoconductive cell, photodiode (CCD, CMOS, NMOS, InGaAs, etc.), etc. In order to measure the chromaticity and spectral spectrum of the fluorescence, a color filter or a diffraction grating may be used in combination as needed. Note that fluorescence is also called detected light.

[0018] The range of the dominant wavelength of the inspection light is preferably 200 to 350 nm, more preferably 220 to 300 nm, and even more preferably 240 to 280 nm, from the viewpoint of increasing the amount of fluorescence from each identification element.

[0019] This glass contains Nb in mole percent based on oxides. ２ O ５ , W.O. ３ , Bi ２ O ３ , CeO ２ , Sm２ O ３ , Eu ２ O ３ and Tb ２ O ３ The glass contains one or more components selected from the group consisting of: in a total amount of 0.001 to 1%. By containing the components in a total amount of 0.001 to 1%, the components can be used as identification elements to efficiently identify the target glass using the fluorescence generated by irradiation with inspection light. The total content of the components is preferably 0.002 to 0.5%, more preferably 0.005 to 0.2%, and even more preferably 0.01 to 0.1%.

[0020] From the viewpoint of efficiently identifying the target glass, the present glass is made of Nb ２ O ５ , W.O. ３ , Bi ２ O ３ , CeO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ Preferably, the polymer contains at least one selected from Bi ２ O ３ , CeO ２ , Eu ２ O ３ and Tb ２ O ３ It is more preferable that the compound contains at least one selected from the following:

[0021] This glass is SnO ２ Contains SnO ２ By containing SnO ２ The target glass can be efficiently identified by using the relationship between the discriminant concentration and SnO as an index. ２ In particular, when produced by the float method, the glass inevitably penetrates into the glass surface.

[0022] The glass has an average SnO content of 1 μm deep from the two opposing main surfaces, expressed in mole percent on an oxide basis. ２ Concentration: The larger average SnO ２ The concentration is [SnO ２Ｂ ], the smaller average SnO２ The concentration is [SnO ２Ｔ ], 10 × [SnO ２Ｔ ]<[SnO ２Ｂ In glass produced by the float process, the surface produced in contact with tin during the production process (hereinafter referred to as the bottom surface) contains a larger amount of SnO than the surface opposite the bottom surface produced without contact with tin (hereinafter referred to as the top surface). ２ Therefore, there is a difference in the amount of fluorescence due to Sn between the top surface and the bottom surface when the inspection light is irradiated. ２ The concentration is Sn ０ , Sn ２＋ , Sn ４＋ The total amount of Sn present in each form is SnO ２ The amount is converted into a quantity and expressed as a concentration relative to the glass.

[0023] This glass is 10×[SnO ２Ｔ ]<[SnO ２Ｂ ], thereby SnO ２ The main surface with the higher concentration and SnO ２ By irradiating the main surface having a lower concentration with inspection light and detecting a difference in the amount of fluorescence due to Sn, glass manufactured by the float process can be efficiently identified. From the viewpoint of more efficiently identifying glass manufactured by the float process, the present glass preferably has a concentration of 100×[SnO ２Ｔ ]<[SnO ２Ｂ ], and more preferably 1000 × [SnO ２Ｔ ]<[SnO ２Ｂ ]. ２Ｂ In order to ensure a sufficient amount of fluorescent light due to Sn, [SnO ２Ｂ can be controlled by the atmosphere and the oxygen concentration in tin when producing a glass sheet by the float process. ２Ｂ ] is preferably 3% or less in order to keep the reflectance of the glass low. ２ＴIn order to make it easier to inspect the fluorescence of the identifying element, the content of ] is preferably 0.3% or less, more preferably 0.1% or less, even more preferably 0.03% or less, and particularly preferably 0.001% or less.

[0024] The present glass satisfies at least one of the following formulas (1a) to (7a): ２ O ５ , W.O. ３ , Bi ２ O ３ , CeO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ In the above formula, [ ] indicates the content of the component in parentheses in mole percent based on oxide. ２Ｂ ]<[Nb ２ O ５ ]<3×[SnO ２Ｂ ] (2a) 0.01×[SnO ２Ｂ ]<[WO ３ ]<3×[SnO ２Ｂ ] (3a) 0.01×[SnO ２Ｂ ]<[Bi ２ O ３ ]<1.5×[SnO ２Ｂ ] (4a)0.01×[SnO ２Ｂ ]<[CeO ２ ]<1.5×[SnO ２Ｂ ] (5a) 0.01×[SnO ２Ｂ ]<[Sm ２ O ３ ]<2.5×[SnO ２Ｂ ] (6a) 0.01×[SnO ２Ｂ ]<[Eu ２ O ３ ]<2.5×[SnO ２Ｂ ] (7a) 0.01×[SnO ２Ｂ ]<[Tb ２ O ３ ]<2.5×[SnO ２Ｂ ]

[0025] The above formulas (1a) to (7a) represent the average SnO ２Average SnO in a range of 1 μm deep on the principal surface with a higher concentration ２ The reason for this is that, for example, in detecting glass, inspection light is irradiated from both main surfaces of the glass, and the fluorescent color produced by the elements contained in the glass is examined to identify the target glass. ２ If the amount is too large compared to the amount of the identifying element, the fluorescence due to the identifying element cannot be detected, and it may be difficult to identify the glass as the target glass. ２ If the amount is too small, it may be impossible to identify that the glass was produced by the float process. Therefore, by satisfying at least one of the above formulas (1a) to (7a), the present glass can be efficiently identified as the target glass.

[0026] Regarding the above (1a) to (7a), from the viewpoint of more efficiently identifying the target glass, it is preferable that each of them is as follows: (1a) Preferably, 0.05 × [SnO ２Ｂ ]<[Nb ２ O ５ ]<2×[SnO ２Ｂ ], more preferably 0.1 × [SnO ２Ｂ ]<[Nb ２ O ５ ]<1×[SnO ２Ｂ ], more preferably 0.2 × [SnO ２Ｂ ]<[Nb ２ O ５ ]<0.5×[SnO ２Ｂ (2a) Preferably, 0.05×[SnO ２Ｂ ]<[WO ３ ]<2×[SnO ２Ｂ ], more preferably 0.1 × [SnO ２Ｂ ]<[WO ３ ]<1×[SnO ２Ｂ ], more preferably 0.2 × [SnO ２Ｂ ]<[WO ３ ]<0.5×[SnO ２Ｂ (3a) Preferably, 0.02×[SnO ２Ｂ ]<[Bi ２ O ３ ]<1×[SnO２Ｂ ], more preferably 0.05×[SnO ２Ｂ ]<[Bi ２ O ３ ]<0.5×[SnO ２Ｂ ], more preferably 0.1 × [SnO ２Ｂ ]<[Bi ２ O ３ ]<0.2×[SnO ２Ｂ (4a) Preferably, 0.02×[SnO ２Ｂ ]<[CeO ２ ]<1×[SnO ２Ｂ ], more preferably 0.05×[SnO ２Ｂ ]<[CeO ２ ]<0.5×[SnO ２Ｂ ], more preferably 0.1 × [SnO ２Ｂ ]<[CeO ２ ]<0.2×[SnO ２Ｂ (5a) Preferably, 0.05×[SnO ２Ｂ ]<[Sm ２ O ３ ]<1.5×[SnO ２Ｂ ], more preferably 0.1 × [SnO ２Ｂ ]<[Sm ２ O ３ ]<0.8×[SnO ２Ｂ ], more preferably 0.2 × [SnO ２Ｂ ]<[Sm ２ O ３ ]<0.3×[SnO ２Ｂ (6a) Preferably, 0.05×[SnO ２Ｂ ]<[Eu ２ O ３ ]<1.5×[SnO ２Ｂ ], more preferably 0.1 × [SnO ２Ｂ ]<[Eu ２ O ３ ]<0.8×[SnO ２Ｂ ], more preferably 0.2 × [SnO ２Ｂ ]<[Eu ２ O ３ ]<0.3×[SnO ２Ｂ (7a) Preferably, 0.05×[SnO ２Ｂ ]<[Tb ２ O ３]<1.5×[SnO ２Ｂ ], more preferably 0.1 × [SnO ２Ｂ ]<[Tb ２ O ３ ]<0.8×[SnO ２Ｂ ], more preferably 0.2 × [SnO ２Ｂ ]<[Tb ２ O ３ ]<0.3×[SnO ２Ｂ ].

[0027] In order to more efficiently identify the target glass, the present glass contains Nb ２ O ５ , W.O. ３ , Bi ２ O ３ , CeO ２ It is preferable that the following formula be satisfied: Since Nb, W, Bi, and Ce have fluorescence wavelengths close to each other, the distinguishability of the glass can be improved by satisfying the following formula: 0.01×[SnO ２Ｂ ]<0.7×[Nb ２ O ５ ]+0.5×[WO ３ ]+2×[Bi ２ O ３ ]+2×[CeO ２ ]<4×[SnO ２Ｂ ] From the viewpoint of further improving the discrimination ability, (0.7 × [Nb ２ O ５ ]+0.5×[WO ３ ]+2×[Bi ２ O ３ ]+2×[CeO ２ ]) is more preferably (0.05 × [SnO ２Ｂ ]) is greater than (3 × [SnO ２Ｂ ]), and more preferably less than (0.1 × [SnO ２Ｂ ]) or more (2 × [SnO ２Ｂ ]) below.

[0028] This glass contains TiO in mole percent based on oxides. ２ The content is preferably 0.001 to 0.1%, more preferably 0.002 to 0.05%, further preferably 0.004 to 0.02%, and particularly preferably 0.006 to 0.01%. ２generates fluorescence when irradiated with light, and if the amount is too large, it will hinder the identification of glass. Therefore, by setting the content within the above range, the identification of the target glass can be further improved.

[0029] This glass contains, in mole percent based on oxides, Fe ２ O ３ The content is preferably 0.001 to 0.1%, more preferably 0.002 to 0.05%, further preferably 0.004 to 0.03%, and particularly preferably 0.005 to 0.01%. ２ O ３ generates fluorescence when irradiated with light, and if the amount is too large, it will hinder the identification of glass. Therefore, by setting the content within the above range, the intended identification of glass can be further improved.

[0030] Since Ti and Fe may reduce the fluorescence intensity of Sm, Eu, and Tb in particular, the relationship between these amounts is important in order to further improve the distinguishability of the glass. From this perspective, it is preferable that the present glass satisfies any one of the following formulas (1b) to (3b): (1b) [Sm ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ] (2b) [Eu ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ] (3b) [Tb ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ]

[0031] From the viewpoint of more efficiently identifying the target glass, the above (1b) to (3b) are preferably as follows: (1b) More preferably, [Sm ２ O ３ ]>3×[Fe ２ O ３ ]+1.5×[TiO ２ ], more preferably [Sm ２ O ３ ]>4×[Fe ２ O ３]+2×[TiO ２ ], particularly preferably [Sm ２ O ３ ]>6×[Fe ２ O ３ ]+3×[TiO ２ (2b) More preferably, [Eu ２ O ３ ]>3×[Fe ２ O ３ ]+1.5×[TiO ２ ], more preferably [Sm ２ O ３ ]>4×[Fe ２ O ３ ]+2×[TiO ２ ], particularly preferably [Sm ２ O ３ ]>6×[Fe ２ O ３ ]+3×[TiO ２ (3b) More preferably, [Tb ２ O ３ ]>3×[Fe ２ O ３ ]+1.5×[TiO ２ ], more preferably [Tb ２ O ３ ]>4×[Fe ２ O ３ ]+2×[TiO ２ ], particularly preferably [Tb ２ O ３ ]>6×[Fe ２ O ３ ]+3×[TiO ２ ].Fe ２ O ３ , TiO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ In the formula, [ ] indicates the content of the component shown in parentheses in mole percent based on the oxide.

[0032] This glass has two opposing main surfaces with an area of ​​0.5 cm ２ It is preferable that the thickness is 1 cm or more, and more preferably 1 cm ２ More preferably, 5 cm２ More than 10 cm, particularly preferably ２ The area of ​​both main surfaces is 0.5 cm ２ By satisfying this condition, a sufficient amount of fluorescent light can be secured, and the target glass can be identified more efficiently. There is no particular upper limit to the area of ​​both main surfaces, but from the viewpoint of improving the efficiency of glass identification, it is usually set to 10,000 cm ２ It is preferable that:

[0033] The type of the glass is not particularly limited, and for example, the composition of the glass is not particularly limited, and the glass may be, for example, a glass selected from the group consisting of soda-lime glass, aluminosilicate glass, alkali-free glass, and alkali borosilicate glass. Soda-lime glass is preferred from the viewpoints of being the most produced glass in the world and contributing greatly to resource recycling and greenhouse gas reduction. Aluminosilicate glass is preferred from the viewpoints that various types of glass are mixed together and that it is expected that the glasses can be easily identified.

[0034] The composition of the present glass contains, in addition to the above-mentioned components, SiO ２ 55-75%, B ２ O ３ 0 to 10%, Al ２ O ３ 0-20%, Na ２ It is preferable that the content of O is 3 to 18%. More preferably, Li ２ It is preferable that the O content is 0.1 to 15%.

[0035] An example of a preferred composition of the present glass will now be described in more detail.

[0036] SiO ２ is the main component of glass. ２ The content of SiO is preferably 55 to 75%. ２ If the content is 55% or more, the weather resistance becomes good, which is preferable. ２ The content of SiO is more preferably 60% or more, and further preferably 64% or more. ２ If the content is 75% or less, devitrification is unlikely to occur, which is preferable. ２The content is more preferably 73% or less, and even more preferably 70% or less.

[0037] B ２ O ３ is a component that improves the chipping resistance and meltability of the glass for chemical strengthening or the chemically strengthened glass. ２ O ３ The content of is preferably 0 to 10%. ２ O ３ is not required, but B ２ O ３ When B is contained, the content is preferably 0.5% or more, more preferably 1% or more, and even more preferably 2% or more in order to improve the melting property. ２ O ３ The content of is preferably 10% or less, more preferably 5% or less, and further preferably 3% or less. ２ O ３ By making the content of B 10% or less, it is possible to prevent the occurrence of striae during melting, which would otherwise cause a deterioration in the quality of the glass for chemical strengthening. ２ O ３ It is preferable that it does not contain

[0038] Al ２ O ３ is a component that improves weather resistance. ２ O ３ The content of Al is not essential, but ２ O ３ When Al is contained, the content is more preferably 0.1% or more, further preferably 1% or more, and particularly preferably 2.5% or more. ２ O ３ The content is preferably 20% or less, more preferably 15% or less, and even more preferably 11% or less.

[0039] Na ２ O is a component that promotes the melting of glass raw materials. ２ The content of O is preferably 3 to 18%. ２ If the O content is 3% or more, the solubility becomes good, which is preferable. ２The O content is more preferably 5% or more, further preferably 10% or more, and particularly preferably 13% or more. ２ If the O content is 18% or less, the weather resistance becomes good, which is preferable. ２ The O content is more preferably 17% or less, and further preferably 16% or less.

[0040] Li ２ O is a component that forms surface compressive stress through ion exchange and reduces the number of fragments when chemically strengthened glass breaks. ２ O is not essential, but Li ２ When O is contained, Li ２ The content of O is preferably 0.1 to 15%. ２ The content of O is more preferably 2% or more, further preferably 5% or more, and particularly preferably 10% or more. ２ The O content is preferably 15% or less, more preferably 14% or less, even more preferably 13% or less, and particularly preferably 12% or less.

[0041] K ２ O is a component that lowers the melting temperature of glass. ２ O is not required, but K ２ When O is contained, K ２ The O content is preferably 0.1 to 5%. ２ The content of O is more preferably 0.2% or more, further preferably 0.5% or more, and particularly preferably 1% or more. ２ The O content is more preferably 4% or less, further preferably 3% or less, and particularly preferably 2% or less.

[0042] MgO is a component that increases the strain point and Young's modulus. Although MgO is not essential, when MgO is contained, the MgO content is preferably 0.1 to 15%. The MgO content is more preferably 0.2% or more, even more preferably 0.5% or more, and particularly preferably 1% or more. Furthermore, in order to make the glass less susceptible to devitrification, the MgO content is more preferably 12% or less, even more preferably 10% or less, and particularly preferably 8% or less.

[0043] CaO is a component that lowers the melting temperature of glass and makes it less susceptible to devitrification. CaO is not essential, but when CaO is contained, the CaO content is preferably 0.1 to 10%. The CaO content is more preferably 0.2% or more, even more preferably 0.5% or more, and particularly preferably 1% or more. In order to lower the thermal expansion coefficient and improve the properties during chemical strengthening, the CaO content is more preferably 8% or less, even more preferably 5% or less, and particularly preferably 2% or less.

[0044] SrO is a component that improves meltability and formability. Although SrO is not essential, when SrO is contained, the SrO content is preferably 0.1 to 5%. The SrO content is more preferably 0.2% or more, even more preferably 0.3% or more, and particularly preferably 0.5% or more. Furthermore, in order to make the glass less susceptible to devitrification, the SrO content is more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1% or less.

[0045] BaO is a component that improves meltability and formability. BaO is not essential, but when BaO is contained, the BaO content is preferably 0.1 to 5%. The BaO content is more preferably 0.2% or more, even more preferably 0.3% or more, and particularly preferably 0.5% or more. In order to make the glass less susceptible to devitrification, the BaO content is more preferably 3% or less, even more preferably 2% or less, and particularly preferably 1% or less.

[0046] ZrO ２ is a component that increases mechanical strength and chemical durability, and may be contained since it significantly improves CS. ２ is not essential, but ZrO ２ When ZrO is contained, it is preferably 0.1% or more, more preferably 0.3% or more, further preferably 0.5% or more, and particularly preferably 1% or more. ２ is preferably 8% or less, more preferably 5% or less, even more preferably 3% or less, and particularly preferably 2% or less.

[0047] In addition, SO is used as a fining agent when melting glass. ３ , chlorides, and fluorides may be appropriately contained. The total content of components functioning as fining agents is preferably 2% or less, more preferably 1% or less, and even more preferably 0.5% or less, expressed as mass% on an oxide basis, since adding too much affects the strengthening properties and crystallization behavior. There is no particular lower limit, but typically, a total of 0.05% or more, expressed as mass% on an oxide basis, is preferred.

[0048] SO as a fining agent ３ SO when using ３ If the content is too small, no effect is observed, so the content is preferably 0.01% or more, more preferably 0.05% or more, and even more preferably 0.1% or more, expressed as mass% on the oxide basis. ３ SO when using ３ The content of is preferably 1% or less, more preferably 0.5% or less, and further preferably 0.3% or less, expressed in mass % on the oxide basis.

[0049] The glass may be chemically strengthened glass. In this specification, "chemically strengthened glass" refers to glass having a compressive stress layer formed on the surface thereof by ion exchange treatment.

[0050] The shape of the present glass is not particularly limited as long as it has two opposing main surfaces, and it may be in various shapes such as a plate, a block, a broken piece, a container, etc. It is preferable that the two opposing main surfaces are parallel to each other. When the glass is in a plate shape, it may be flat, or may be formed or bent so as to include, for example, a partially curved surface. When the glass is in a plate shape, there are no particular limitations on the thickness, but it is preferably 0.1 to 20 mm, more preferably 0.4 to 10 mm, and even more preferably 0.6 to 5 mm.

[0051] The present glass can be manufactured, for example, as follows. The following manufacturing method is an example of manufacturing a plate-shaped glass. First, the raw materials for the glass components are blended and heated and melted in a glass melting furnace. The glass is then homogenized by bubbling, stirring, adding a fining agent, etc., and formed into a glass plate of a predetermined thickness by a conventional forming method, followed by annealing.

[0052] Examples of glass forming methods include the float method, press method, fusion method, and down-draw method. The float method, which is suitable for mass production, is particularly preferred. The formed glass is then ground and polished as necessary to form a glass substrate.

[0053] <Glass Identification Method> The glass identification method of this embodiment (hereinafter also referred to as this method) is characterized by including the following (1c) and (2c): (1c) Irradiating inspection light onto a glass having two opposing principal surfaces from each of the two principal surfaces to obtain fluorescence of a detectable intensity; (2c) Using the chromaticity of the fluorescence obtained in (1c) as defined below: Ｂ and θ Ｔ Absolute value of the difference between |θ Ｂ－ θ Ｔ Evaluate whether θ | is 5 degrees or more for one of the principal surfaces. Ｂ is a value that satisfies the following formulas (1) and (2), and θ Ｔ is a value that satisfies the following formulas (3) and (4). ＊ a ＊ b ＊ The chromaticity of the fluorescence in the color system is a ＊ Ｂ , b ＊ Ｂ In the following formulas (3) and (4), L of the other main surface ＊ a ＊ b ＊ The chromaticity of the fluorescence in the color system is a ＊ Ｔ , b ＊ Ｔ Let sinθ Ｂ = b ＊ Ｂ / (a ＊ Ｂ２ +b ＊ Ｂ ２ ) ０．５ ...Formula (1) cosθ Ｂ = a ＊ Ｂ / (a ＊ Ｂ ２ +b ＊ Ｂ ２ ) ０．５ ...Equation (2) sin θ Ｔ = b ＊ Ｔ / (a ＊ Ｔ ２ +b ＊ Ｔ ２ ) ０．５ ...Formula (3) cosθ Ｔ = a ＊ Ｔ / (a ＊ Ｔ ２ +b ＊ Ｔ ２ ) ０．５ ...Formula (4)

[0054] In step (1c), the inspection light irradiated onto both main surfaces is preferably from the same light source and has approximately the same dominant wavelength. The inspection light is similar to the inspection light described above in the section on <Glass>.

[0055] In step (2c), the fluorescence on both main surfaces is calculated by |θ Ｂ－ θ Ｔ If |θ is 5 degrees or more, the glass can be identified as the intended glass. Ｂ－ θ Ｔ is preferably 10 degrees or more, more preferably 20 degrees or more, and even more preferably 50 degrees or more.

[0056] One embodiment of the present method will be described with reference to Fig. 1. Specific examples of one embodiment of the present method include an embodiment that includes the following steps: (i) irradiating one main surface of the glass 10 to be inspected with inspection light 11, obtaining fluorescence of a detectable intensity, and measuring the chromaticity of the fluorescence; (ii) irradiating the other main surface opposite the main surface irradiated with inspection light 11 in step (i) with inspection light 12 on the glass 10 to be inspected, obtaining a detectable intensity of fluorescence, and measuring the chromaticity of the fluorescence; (iii) calculating the chromaticity of the fluorescence measured in steps (i) and (ii) by using θ Ｂ and θ Ｔ Absolute value of the difference between |θ Ｂ－ θ Ｔ is 5 degrees or more.

[0057] In one aspect of this method, inspection may be performed on glass that is falling freely. In addition, inspection may be performed on glass that is automatically transported. In this case, the belt is preferably light-transmitting so that inspection light is irradiated onto both main surfaces. As a light-transmitting belt, for example, a mesh with a mesh size of 3 to 50 mm is preferred, a mesh with a mesh size of 5 to 40 mm is more preferred, and a mesh with a mesh size of 7 to 30 mm is particularly preferred. In one aspect of this method, θ Ｂ and θ Ｔ Absolute value of the difference between |θ Ｂ－ θ Ｔ Glass having an angle | of less than 5 degrees may be removed by a method such as blowing it off with an air current during free fall or after automatic transport. Ｂ and θ Ｔ Absolute value of the difference between |θ Ｂ－ θ Ｔ Glass having a | of 5 degrees or more may be selected by blowing it off with an air current during free fall or after automatic transport.

[0058] One embodiment of the present invention is a method for sorting glass that includes the present method.

[0059] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0060] Glass plates with a thickness of 4 mm were prepared by the float process so as to have the compositions shown in Table 1 in mole percent based on oxides, and the obtained glass plates were cut to the desired size (main surface: 30 mm x 30 mm). In Table 1, the average SnO ２ Concentration: The larger average SnO ２ The concentration is "SnO ２Ｂ ", the smaller average SnO ２ The concentration is "SnO ２Ｔ " is expressed as ".

[0061] Using a spectrofluorometer (Hitachi High-Tech F-7000), two opposing main surfaces of the obtained glass plate were irradiated with light having a dominant wavelength of 260 nm obtained by splitting a xenon lamp with a diffraction grating as inspection light, and the fluorescence was measured. It was determined whether the intensity of the fluorescence was sufficiently large compared to the noise. Furthermore, from the obtained fluorescence spectrum, L ＊ a ＊ b ＊ The chromaticity of the fluorescence was calculated in a color system, and the results are shown in Table 1. In Table 1, Examples 1 to 5 are working examples, and Examples 6 and 7 are comparative examples.

[0062] In Table 1, θ Ｂ is a value that satisfies the following formulas (1) and (2) for one of the main surfaces, and θ Ｔ is a value that satisfies the following formulas (3) and (4) for the other main surface. ＊ a ＊ b ＊ The chromaticity of the fluorescence in the color system is a ＊ Ｂ , b ＊ Ｂ In the following formulas (3) and (4), L of the other main surface ＊ a ＊ b ＊ The chromaticity of the fluorescence in the color system is a ＊ Ｔ , b ＊ Ｔ sinθ Ｂ = b ＊ Ｂ / (a ＊ Ｂ ２ +b＊ Ｂ ２ ) ０．５ ...Formula (1) cosθ Ｂ = a ＊ Ｂ / (a ＊ Ｂ ２ +b ＊ Ｂ ２ ) ０．５ ...Equation (2) sin θ Ｔ = b ＊ Ｔ / (a ＊ Ｔ ２ +b ＊ Ｔ ２ ) ０．５ ...Formula (3) cosθ Ｔ = a ＊ Ｔ / (a ＊ Ｔ ２ +b ＊ Ｔ ２ ) ０．５ ...Formula (4)

[0063] The "detection of fluorescence" in Table 1 was evaluated according to the following criteria: ◯: The fluorescence intensity is sufficiently greater than the noise and is equal to or greater than the detection limit. ×: The fluorescence intensity is not sufficiently greater than the noise and is less than the detection limit.

[0064]

[0065] As shown in Table 1, in Examples 1 to 5, which are glasses of this embodiment, the fluorescence intensity is sufficiently large compared to the noise, and the absolute value of the difference in chromaticity between both principal surfaces |θ Ｂ－ θ Ｔ was 5 degrees or more, and it was found that the target glass could be efficiently identified as compared with Examples 6 and 7 which were comparative examples.

[0066] This application is based on Japanese Patent Application No. 2023-187763 filed on November 1, 2023, the contents of which are incorporated herein by reference.

[0067] 10 Glass 11, 12 Inspection light

Claims

1. A substrate having two opposing main surfaces and made of SnO ２ Contains, expressed in mole percent on an oxide basis, Nb ２ O ５ , W.O. ３ , Bi ２ O ３ , CeO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ The average SnO content in a range of 1 μm deep from each of the two main surfaces is 0.001 to 1% in total, expressed as mole percent on an oxide basis. ２ Concentration: Larger average SnO ２ The concentration is [SnO ２Ｂ ], the smaller average SnO ２ The concentration is [SnO ２Ｔ ], 10 × [SnO ２Ｔ ]<[SnO ２Ｂ ] and a glass satisfying at least one of the following formulas (1a) to (7a): (1a) 0.01 × [SnO ２Ｂ ]<[Nb ２ O ５ ]<3×[SnO ２Ｂ ] (2a) 0.01×[SnO ２Ｂ ]<[W.O. ３ ]<3×[SnO ２Ｂ ] (3a) 0.01×[SnO ２Ｂ ]<[Bi ２ O ３ ]<1.5×[SnO ２Ｂ ] (4a)0.01×[SnO ２Ｂ ]<[CeO ２ ]<1.5×[SnO ２Ｂ ] (5a) 0.01×[SnO ２Ｂ ]<[Sm ２ O ３ ]<2.5×[SnO ２Ｂ ] (6a)0.01×[SnO ２Ｂ ]<[Eu ２ O ３ ]<2.5×[SnO ２Ｂ ] (7a) 0.01×[SnO ２Ｂ ]<[Tb ２ O ３ ]<2.5×[SnO ２Ｂ ] Nb ２ O ５ , W.O. ３ , Bi ２ O ３ , CeO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ In the above formula, the brackets [ ] represent the content of the component in parentheses in mole percent based on the oxide.

2. In terms of oxide mol%, TiO ２ The glass according to claim 1, containing 0.001 to 0.1% of 3. Fe, expressed as mole percent on an oxide basis ２ O ３ The glass according to claim 1, containing 0.001 to 0.1% of 4. Fe, expressed as mole percent on an oxide basis ２ O ３ The glass according to claim 2, containing 0.001 to 0.1% of 5. The glass according to any one of claims 2 to 4, which satisfies any one of the following formulas (1b) to (3b): (1b) [Sm ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ] (2b) [Eu ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ] (3b) [Tb ２ O ３ ]>2×[Fe ２ O ３ ]+[TiO ２ ] Fe ２ O ３ , TiO ２ , Sm ２ O ３ , Eu ２ O ３ and Tb ２ O ３ In the above formula, [ ] indicates the content of the component shown in the brackets in mole % based on the oxide.

6. The area of ​​the two main surfaces is 0.5 cm ２ The glass according to claim 1 or 2, 7. In terms of oxide mole percent, SiO ２ 55-75% B ２ O ３ 0 to 10% Al ２ O ３ 0 to 20%, Na ２ 3. The glass according to claim 1, containing 3 to 18% O.

8. In mole percent based on oxide, Li ２ The glass according to claim 7, containing 0.1 to 15% O.

9. A method for identifying glass, including the following (1c) and (2c): (1c) Irradiating an inspection light onto each of two opposing principal surfaces of a glass sheet to obtain fluorescence of a detectable intensity. (2c) The chromaticity of the fluorescence obtained in (1c) is calculated by the following equation: Ｂ and θ Ｔ Absolute value of difference |θ Ｂ－ θ Ｔ Evaluate whether θ | is 5 degrees or more. Ｂ is a value that satisfies the following formulas (1) and (2) for one of the main surfaces, and θ Ｔ is a value that satisfies the following formulas (3) and (4) for the other main surface. ＊ a ＊ b ＊ The chromaticity of the fluorescence in the color system is a ＊ Ｂ , b ＊ Ｂ In the following formulas (3) and (4), L of the other main surface is ＊ a ＊ b ＊ The chromaticity of the fluorescence in the color system is a ＊ Ｔ , b ＊ Ｔ Let sinθ Ｂ = b ＊ Ｂ / (a ＊ Ｂ ２ +b ＊ Ｂ ２ ) ０．５ ...Formula (1) cosθ Ｂ = a ＊ Ｂ / (a ＊ Ｂ ２ +b ＊ Ｂ ２ ) ０．５ ...Equation (2) sin θ Ｔ = b ＊ Ｔ / (a ＊ Ｔ ２ +b ＊ Ｔ ２ ) ０．５ ...Formula (3) cosθ Ｔ = a ＊ Ｔ / (a ＊ Ｔ ２ +b ＊ Ｔ ２ ) ０．５ ...Formula (4)

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