Glass and method for producing same

Abstract

Provided is a glass which can replace a Li2O-Al2O3-SiO2-based crystallized glass and which has a low coefficient of linear thermal expansion and excellent light transmittance. A glass characterized by containing, in mass%, 45 to 80% of SiO2, 10 to 30% of Al2O3, 0 to 12% of B2O3, and 0 to 5% of Li2O.

Description

TECHNICAL FIELD

[0001] The present application relates to a glass having low linear thermal expansion properties. BACKGROUND

[0002] In the related art, as a material for a front window of a kerosene stove, a wood stove, etc., a fixing device for electronic parts, a core tube for semiconductor manufacturing, a member for size measurement, a member for communication, a member for construction, a container for chemical reaction, a top plate for electromagnetic cooking, heat-resistant tableware, a heat-resistant cover, a window glass for a fireproof door, a member for a celestial telescope, a linear thermal expansion coefficient adjustment member, etc., a crystallized glass is used. For example, in Patent Documents 1 to 3, a crystallized glass in which a β-quartz solid solution (Li2O-Al2O3-nSiO2 [where 2≤n≤4]) or a β-spodumene solid solution (Li2O-Al2O3-nSiO2 [where n≥4]) or the like of a Li2O-Al2O3-SiO2 system crystal is precipitated as a main crystal is disclosed.

[0003] The crystallized glass has low linear thermal expansion coefficient and also high mechanical strength, and thus has excellent thermal properties. In addition, by appropriately adjusting the heat treatment conditions in the crystallization step, the type of precipitated crystal can be controlled, and a crystallized glass having high light transmittance can be easily produced.

[0004] RELATED ART DOCUMENTS PATENT DOCUMENTS Patent Document 1: Japanese Patent Publication No. 39-21049 Patent Document 2: Japanese Patent Publication No. 40-20182 Patent Document 3: Japanese Patent Application Laid-Open No. 1-308845 SUMMARY

[0005] PROBLEMS TO BE SOLVED BY THE INVENTION In recent years, along with an increase in demand for electric vehicles and electronic devices such as smartphones and tablet computers, the market for lithium ion batteries has expanded. Therefore, in each industry, lithium raw materials are insufficient, and the price of lithium raw materials is rising worldwide. Thus, it is becoming increasingly difficult to stably produce and supply Li2O-Al2O3-SiO2 system crystallized glass to the market.

[0006] Based on such a background, there is a demand for a material having low linear thermal expansion coefficient and excellent light transmittance, which can replace Li2O-Al2O3-SiO2 system crystallized glass.

[0007] An object of the present application is to provide a glass having low linear thermal expansion coefficient and excellent light transmittance, which can replace Li2O-Al2O3-SiO2 system crystallized glass.

[0008] TECHNICAL SOLUTION FOR SOLVING THE PROBLEMS The inventors of the present application have found that, by appropriately designing the glass composition, a glass having a low linear thermal expansion coefficient and excellent light transmittance can be obtained. The "light transmittance" refers to the transmittance (total light transmittance) at any one of the wavelengths of 1200 nm, 800 nm, 555 nm, 380 nm, and 300 nm being more than 0% at a thickness of 4 mm.

[0009] The glass of the present application contains, in mass%, 45 to 80% of SiO2, 10 to 30% of Al2O3, 0 to 12% of B2O3, and 0 to 5% of Li2O.

[0010] The glass of the present application preferably contains, in mass%, more than 0% of P2O5.

[0011] The glass of the present application preferably contains, in mass%, more than 0% of TiO2.

[0012] The glass of the present application preferably contains, in mass%, more than 0% and 8% or less of B2O3, 0 to 3% of Li2O, and 6.5 to 20% of P2O5.

[0013] The glass of the present application preferably contains, in mass%, more than 0% of Fe2O3.

[0014] The glass of the present application preferably contains, in mass%, 10% or less of HfO2.

[0015] The glass of the present application preferably contains, in mass%, 0.05% or less of Pt and 0.05% or less of Rh.

[0016] The glass of the present application preferably contains, in mass%, more than 0% of SnO2.

[0017] The glass of the present application preferably contains, in mass%, 12.5% or less of ZnO.

[0018] The glass of the present application preferably contains, in mass%, 15% or less of Li2O + Na2O + K2O.

[0019] The glass of the present application preferably contains, in mass%, more than 0% of ZrO2.

[0020] The glass of the present application preferably contains, in mass%, (P2O5 x TiO2) / (Al2O3 + P2O5) of 0.01 or more.

[0021] The glass of the present application preferably contains, in mass%, P2O5 x TiO2 of 0.22 or more.

[0022] The glass of the present application preferably has 5.9% or less of MgO+CaO+SrO+BaO, 2.6% or less of Li2O+Na2O+K2O, and 0.01 or more of P2O5xTiO2 in mass %.

[0023] The glass of the present application preferably has a linear thermal expansion coefficient of 60x10 －7 / °C or less at 30 to 750°C.

[0024] The glass of the present application preferably has a transmittance of 0.1% or more at a thickness of 4 mm and a wavelength of 555 nm.

[0025] The glass of the present application is preferably used for a top plate for a cooking appliance, a fireproof window, heat-resistant tableware, or a building component.

[0026] The glass of the present application is characterized by containing 45 to 80% of SiO2, 10 to 30% of Al2O3, 0 to 12% of B2O3, more than 0% and 20% or less of P2O5, 0 to 5% of MgO+CaO+SrO+BaO, 0 to 5% of Li2O+Na2O+K2O in mass %, and (P2O5xTiO2) / (Al2O3+P2O5) is 1.4 or more, and a linear thermal expansion coefficient is 40x10 －7 / °C or less at 30 to 750°C.

[0027] The glass of the present application is characterized by containing 45 to 80% of SiO2, 10 to 30% of Al2O3, 0 to 12% of B2O3, more than 0% and 20% or less of P2O5, 5% or less of Li2O, more than 0% and 20% or less of ZrO2, 0 to 8% of MgO+CaO+SrO+BaO, 0 to 2.9% of Li2O+Na2O+K2O in mass %, and (MgO+CaO+SrO+BaO) / P2O5 is 3.8 or less, and a linear thermal expansion coefficient is 40x10 －7 / °C or less at 30 to 750°C.

[0028] The glass of the present application is characterized by having a linear thermal expansion coefficient of 5 to 40x10 －7 / °C at 30 to 380°C and 30 to 750°C, and a transmittance of 0.1% or more at a thickness of 4 mm and a wavelength of 555 nm.

[0029] The method for producing the glass of the present application is a method for producing any of the above-described glasses, characterized by comprising a step of melting a glass raw material to obtain a molten glass, and a step of molding the molten glass, and the method for molding the molten glass is at least one or more selected from the group consisting of an overflow method, a float method, a down-draw method, a flow-hole down-draw method, a re-draw method, a containerless method, a blowing method, a press method, a roll press method, a casting method, and a tube drawing method.

[0030] Inventive Effects According to the present application, there is provided a glass having excellent light transmittance and thermal properties, which can replace Li2O-Al2O3-SiO2-based crystallized glass. DETAILED DESCRIPTION

[0031] The glass of the present application (hereinafter also simply referred to as "glass") is characterized by containing 45 to 80% of SiO2, 10 to 30% of Al2O3, 0 to 12% of B2O3, and 0 to 5% of Li2O, in terms of mass%. The reasons for setting the contents of the respective components and the properties as described above are described below. In the following description of the contents of the respective components, " % " means " mass% " unless otherwise specifically stated.

[0032] SiO2is a component that forms a glass skeleton, and is also a component that particularly affects the ease of phase separation. The content of SiO2is 45 to 80%, and the lower limit is preferably 46% or more, 47% or more, 48% or more, and particularly 49% or more, and the upper limit is preferably 79% or less, 78% or less, 77% or less, and particularly 76% or less. When the content of SiO2is too low, there is a tendency for the linear thermal expansion coefficient to increase, and it is difficult to obtain a glass having excellent heat resistance and thermal shock resistance. Furthermore, there is a tendency for the chemical durability to decrease. On the other hand, when the content of SiO2is too high, the homogeneity of the glass melt easily decreases. Furthermore, scum having a high content of SiO2easily occurs on the surface of the glass melt, and devitrifying substances such as kyanite are precipitated from the scum, and the manufacturing load easily increases. Here, the scum is an unreacted substance and a floating substance on the surface of the glass melt in the melting furnace, and refers to a substance in which kyanite is the main component.

[0033] Al2O3is a component that forms a glass skeleton, and is also a component that affects the ease of phase separation. The content of Al2O3is 10 to 30%, and the lower limit is preferably 11% or more, 12% or more, 13% or more, 14% or more, and particularly 15% or more, and the upper limit is preferably 29% or less, 28% or less, 27% or less, and particularly 26% or less. When the content of Al2O3is too low, there is a tendency for the linear thermal expansion coefficient to increase, and it is difficult to obtain a glass having excellent heat resistance and thermal shock resistance. Furthermore, the chemical durability decreases, and the surface of the glass easily deteriorates. As a result, the state of the surface becomes poor, and it is difficult to obtain a glass having a desired transmittance. On the other hand, when the content of Al2O3is too high, the homogeneity of the glass melt easily decreases. Furthermore, there is a tendency for crystals such as mullite to precipitate and cause the glass to devitrify, and the glass easily breaks.

[0034] B2O3 is a component that lowers the viscosity of the glass and improves the melting property and the moldability of the glass, and is also a component that particularly affects the ease of phase separation, and has the effect of lowering the coefficient of linear thermal expansion, improving the heat resistance, and improving the thermal shock resistance. The content of B2O3 is 0 to 12%, and the lower limit is preferably more than 0%, more than 0.5%, more than 1%, particularly more than 1.5%, and the upper limit is preferably 11.5% or less, 11% or less, 10.5% or less, 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.85% or less, 7.8% or less, 7.7% or less, 7.5% or less, 7% or less, 6.5% or less, 6.4% or less, 6.3% or less, 6.2% or less, 6.1% or less, 6% or less, 5.9% or less, 5.8% or less, 5.7% or less, 5.6% or less, 5.5% or less, 5.4% or less, 5.3% or less, 5.2% or less, 5.1% or less, particularly 5% or less. When the content of B2O3 is too much, the evaporation amount of B2O3 increases at the time of melting, and dross in which the content of B2O3 is low and the content of SiO2 is relatively high is easily generated on the surface of the glass melt. As a result, devitrification products such as cristobalite are easily precipitated from the dross, and the manufacturing load increases. Also, the chemical durability of the glass decreases, the surface of the glass easily deteriorates, and thus the surface unevenness state deteriorates, and it is difficult to obtain a glass having a desired high transmittance. On the other hand, B2O3 is easily mixed as an impurity, and thus, if it is desired to completely remove B2O3, there is a tendency that the price of the raw material batch increases, and the manufacturing cost increases. In the case where the increase in the manufacturing cost is suppressed, B2O3 can be contained at 0.0001% or more, 0.0003% or more, particularly 0.0005% or more.

[0035] Li₂O is a component that reduces the viscosity of glass and improves its meltability and formability, but it can also affect phase separation in glass. The Li₂O content is 0–5%, with the upper limits preferably below 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.9%, 1.8%, 1.5%, 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, and particularly below 0.3%. When the Li₂O content is too high, the linear coefficient of thermal expansion becomes excessively large, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt tends to decrease. Moreover, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. Furthermore, Li₂O is easily introduced as an impurity. Therefore, if Li₂O is to be completely removed, the price of raw materials will increase, leading to higher manufacturing costs. Therefore, to suppress the increase in manufacturing costs, the lower limit of Li₂O content is preferably greater than 0%, 0.0001% or more, 0.0002% or more, 0.0003% or more, 0.0004% or more, 0.0005% or more, and particularly 0.001% or more.

[0036] In addition to the above-mentioned components, the glass of the present invention may also contain the following components.

[0037] In the glass of the present invention, P2O5 is a component that reduces the linear coefficient of thermal expansion of the glass, is used to adjust the refractive index, and also affects phase separation of the glass. The P2O5 content is preferably 0-30%. The lower limit is preferably greater than 0%, 0.1% or more, 1% or more, 2% or more, 3% or more, 4% or more, 4.5% or more, and particularly 6.5% or more; the upper limit is preferably less than 25%, less than 20%, less than 18%, less than 17%, and particularly less than 16%. When the P2O5 content is too high, the viscosity of the glass becomes too high, and the homogeneity of the glass melt is easily reduced. Furthermore, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired transmittance. Moreover, the resistance to devitrification is easily reduced.

[0038] In the glass of this invention, P2O5 is a component that reduces the linear coefficient of thermal expansion of the glass. However, when the P2O5 content is too high, the viscosity of the glass increases, and the meltability of the glass tends to decrease. On the other hand, B2O3 is a component that can reduce the viscosity of the glass. When the viscosity of the glass is too high, for example, higher temperatures are required during glass melting and forming, manufacturing equipment is easily overloaded, energy costs are easily increased, and productivity tends to decrease. Therefore, in order to reduce the linear coefficient of thermal expansion and reduce the viscosity of the glass to obtain glass with good productivity, it is preferable to strictly control the B2O3 / P2O5 ratio (the quotient of the content of B2O3 and P2O5). The B2O3 / P2O5 ratio is preferably 0 or more, 0.01 or more, 0.1 or more, 0.2 or more, especially 0.3 or more, and preferably 550 or less, 300 or less, 100 or less, 50 or less, 10 or less, especially 1 or less.

[0039] TiO2 is a component that reduces glass viscosity and improves its meltability and formability by being present in appropriate amounts. It also reduces the linear coefficient of thermal expansion and is a coloring component for glass that absorbs light of various wavelengths. It is known to exhibit a coloring similar to ilmenite (FeTiO3), especially in the presence of titanium and iron; and a stronger yellow hue in the presence of titanium and tin. Furthermore, TiO2 is a component that particularly affects the ease of phase separation. The preferred TiO2 content is 0% or more, greater than 0%, 0.001% or more, 0.01% or more, 0.1% or more, 1% or more, 2% or more, 3% or more, 4% or more, 5% or more, particularly 6% or more, preferably 20% or less, 18% or less, 16% or less, 14% or less, particularly 12% or less. Additionally, when the TiO2 content is greater than 0%, the linear coefficient of thermal expansion tends to decrease. Excessive TiO2 content tends to decrease the meltability of the glass. Moreover, the glass is easily colored, making it difficult to obtain glass with the desired high transmittance. Therefore, for example, in the case of obtaining a glass with a colorless and highly transparent appearance, the TiO2 content can be less than 3%, less than 2%, or less than 1%.

[0040] In the glass of the present invention, P2O5 is a component capable of reducing the linear coefficient of thermal expansion of the glass, and its effect tends to be better than that of TiO2. However, regarding the viscosity of the glass, P2O5 is a component that easily increases it, while TiO2 is a component that easily decreases it. Therefore, in order to reduce the linear coefficient of thermal expansion and appropriately suppress the increase in glass viscosity to obtain glass with good productivity, it is preferable to strictly control the P2O5×TiO2 (the product of the contents of P2O5 and TiO2). P2O5×TiO2 is preferably 0 or more, greater than 0, 0.00002 or more, 0.0001 or more, 0.001 or more, 0.01% or more, 0.1 or more, 0.22 or more, 0.23 or more, 0.25% or more, 1 or more, 3 or more, 5 or more, 7 or more, 10 or more, especially 15 or more, and preferably 900 or less, 500 or less, 300 or less, 150 or less, 100 or less, 80 or less, especially 60 or less. When the P2O5×TiO2 ratio is too high, the viscosity of the glass tends to increase, thus reducing productivity. Furthermore, to obtain glass with a low linear coefficient of thermal expansion, a P2O5×TiO2 ratio greater than 0% is preferred.

[0041] Both P2O5 and TiO2 are components that reduce the linear coefficient of thermal expansion. P2O5 increases the viscosity of glass, while TiO2 decreases it. Additionally, Al2O3 forms the glass framework and can also reduce the linear coefficient of thermal expansion. However, when Al2O3 is present in excessive amounts compared to P2O5 and TiO2, it can decrease the glass viscosity and increase the liquidus temperature, thus reducing productivity. Therefore, in order to obtain glass with a low coefficient of linear expansion and high productivity, the ratio of (P2O5×TiO2) / (Al2O3+P2O5) (the ratio of the product of the contents of P2O5 and TiO2 to the sum of the contents of Al2O3 and P2O5) is preferably 0 or more, greater than 0, 0.000001 or more, 0.000002 or more, 0.0000016 or more, 0.00001 or more, 0.0001 or more, 0.001 or more, 0.01 or more, 0.1 or more, 1.0 or more, 1.2 or more, 1.4 or more, 1.5 or more, 1.7 or more, especially 1.9 or more, and preferably 10 or less, 5 or less, especially 4 or less.

[0042] Fe2O3 is a component that reduces glass viscosity and improves glass meltability and formability when present in appropriate amounts. However, it is also a component that releases oxygen-based gases through redox reactions, and thus can affect glass clarity. Furthermore, it is a coloring component that absorbs light of various wavelengths, and can also affect phase separation in the glass. The preferred Fe2O3 content is 0% or more, greater than 0%, 0.0001% or more, 0.001% or more, 0.005% or more, and particularly 0.01% or more. On the other hand, when the Fe2O3 content is too high, the glass is easily colored, making it difficult to obtain the desired high transmittance. Furthermore, Fe-containing devitrifying substances are easily precipitated, increasing the manufacturing burden. Therefore, the preferred Fe2O3 content is 20% or less, 15% or less, 10% or less, 5% or less, 1% or less, 0.5% or less, and particularly 0.1% or less. Additionally, the Fe2O3 content can be controlled to adjust the transmittance according to the intended use of the glass according to the present invention. For example, when a colored (e.g., black) appearance is required in cooking top plates or the like, the Fe2O3 content can be 0.05% or more, 0.08% or more, 0.1% or more, 0.2% or more, and especially 0.3% or more.

[0043] Sodium oxychloride (Na₂O) is a component that reduces glass viscosity and improves its melt flow and formability. It is also used to adjust the linear coefficient of thermal expansion and refractive index of glass, and it affects glass clarity. The preferred Na₂O content is 15% or less, 10% or less, 7% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2% or less, 1% or less, 0.7% or less, 0.4% or less, 0.1% or less, and particularly 0.05% or less. When the Na₂O content is too high, the linear coefficient of thermal expansion becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt tends to decrease. Moreover, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. In addition, Na₂O is easily introduced as an impurity; therefore, if Na₂O is to be completely removed, there is a tendency for the price of raw materials to increase, leading to increased manufacturing costs. While suppressing the increase in manufacturing costs, the lower limit of Na2O content is preferably greater than 0%, and is more than 0.0001%, more than 0.0003%, more than 0.0005%, more than 0.001%, more than 0.002%, more than 0.004%, more than 0.006%, more than 0.008%, and especially more than 0.01%.

[0044] K₂O is a component that reduces glass viscosity and improves its melt and formability. It is also used to adjust the linear thermal expansion coefficient and refractive index of glass, and it affects phase separation. The preferred K₂O content is 15% or less, 10% or less, 7% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2% or less, 1% or less, 0.7% or less, 0.4% or less, 0.1% or less, and particularly 0.05% or less. When the K₂O content is too high, the linear thermal expansion coefficient becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt tends to decrease. Additionally, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. Moreover, K₂O is easily introduced as an impurity; therefore, if K₂O is to be completely removed, there is a tendency for the price of raw materials to increase, leading to increased manufacturing costs. While suppressing the increase in manufacturing costs, the lower limit of K2O content is preferably greater than 0%, greater than 0.0001%, greater than 0.0003%, greater than 0.0005%, and especially greater than 0.001%.

[0045] Li2O, Na2O, and K2O are all components that reduce glass viscosity and improve glass meltability and formability. They are also components that affect phase separation in glass. The content of Li2O + Na2O + K2O (the total content of Li2O, Na2O, and K2O) is preferably less than 15%, less than 10%, less than 7%, less than 5%, less than 4.5%, less than 4%, less than 3.5%, less than 3%, less than 2.9%, less than 2.8%, less than 2.7%, less than 2.6%, less than 2.5%, less than 2.4%, less than 2.3%, less than 2.2%, less than 2.1%, less than 2%, less than 1.9%, less than 1.8%, less than 1.7%, less than 1.6%, less than 1.5%, less than 1.4%, less than 1.3%, less than 1.2%, less than 1.1%, less than 1%, less than 1%, and especially less than 0.05%. When there is an excess of Li₂O + Na₂O + K₂O, the linear coefficient of thermal expansion becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt tends to decrease. Moreover, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface texture deteriorates, making it difficult to obtain glass with the desired high transmittance. Additionally, Li₂O, Na₂O, and K₂O are easily incorporated as impurities; therefore, completely removing them tends to increase the price of raw materials, leading to increased manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of the Li₂O + Na₂O + K₂O content is preferably greater than 0%, 0.0001% or more, 0.001% or more, and particularly 0.01% or more.

[0046] MgO is a component that reduces glass viscosity and improves its melt and formability. It is also used to reduce the linear coefficient of thermal expansion and adjust the refractive index, and it affects phase separation in glass. The preferred MgO content is 0% or more, 1% or more, 2% or more, 3% or more, particularly 4% or more, and preferably 40% or less, 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, particularly 6% or less. When the MgO content is too high, the linear coefficient of thermal expansion becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. In addition, MgO is easily incorporated as an impurity; therefore, if MgO is to be completely removed, the price of raw materials tends to increase, leading to higher manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of MgO content is preferably 0.0001% or more, 0.001% or more, and especially 0.01% or more.

[0047] CaO is a component that reduces glass viscosity and improves its meltability and formability. It is also used to adjust the linear thermal expansion coefficient and refractive index of glass, and it affects phase separation. The preferred CaO content is 0% or more, 1% or more, 2% or more, 3% or more, particularly 4% or more, and preferably 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, particularly 6% or less. When the CaO content is too high, the linear thermal expansion coefficient becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt tends to decrease. Moreover, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. In addition, CaO is easily introduced as an impurity; therefore, if CaO is to be completely removed, the price of raw materials tends to increase, leading to higher manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of CaO content is preferably 0.0001% or more, 0.001% or more, and especially 0.01% or more.

[0048] SrO is a component that reduces glass viscosity and improves glass meltability and formability. It is also used to adjust the linear thermal expansion coefficient and refractive index of glass, and it affects phase separation in glass. The SrO content is preferably 0% or more, 1% or more, 2% or more, 3% or more, particularly 4% or more, and preferably 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, particularly 6% or less. When the SrO content is too high, the linear thermal expansion coefficient becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt tends to decrease. Moreover, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. In addition, SrO is easily introduced as an impurity; therefore, if SrO is to be completely removed, the price of raw materials tends to increase, leading to increased manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of SrO content is preferably 0.0001% or more, 0.001% or more, and especially 0.01% or more.

[0049] BaO is a component that reduces glass viscosity and improves its melt flow and formability. It is also used to adjust the linear thermal expansion coefficient and refractive index of glass, and it affects phase separation. The BaO content is preferably 0% or more, 1% or more, 2% or more, 3% or more, particularly 4% or more, and preferably 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, particularly 6% or less. When the BaO content is too high, the linear thermal expansion coefficient becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the melt flow of the glass tends to decrease. Moreover, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. In addition, BaO is easily introduced as an impurity; therefore, if BaO is to be completely removed, the price of raw materials tends to increase, leading to increased manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of BaO content is preferably 0.0001% or more, 0.001% or more, and especially 0.01% or more.

[0050] MgO, CaO, SrO, and BaO are all components that reduce glass viscosity and improve its melt flowability and formability. On the other hand, MgO, CaO, SrO, and BaO also increase the linear expansion coefficient of glass. Excessive amounts of these components can make it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, there is a tendency for the chemical durability of the glass to decrease, and the glass surface to easily deteriorate. As a result, the surface texture deteriorates, making it difficult to obtain glass with the desired high transmittance. Therefore, the content of MgO + CaO + SrO + BaO (the total content of MgO, CaO, SrO, and BaO) is preferably 40% or less, 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, and especially 0.1% or less. Furthermore, in order to improve the meltability and formability of the glass, it is preferably 0.1% or more, 1% or more, 2% or more, 3% or more, and especially 4% or more. Furthermore, MgO, CaO, SrO, and BaO are easily mixed in as impurities. Therefore, if they are to be completely removed, the price of raw materials will increase, leading to an increase in manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of the MgO+CaO+SrO+BaO content is preferably greater than 0%, greater than 0.0001%, greater than 0.0003%, greater than 0.0005%, and especially greater than 0.001%.

[0051] MgO, CaO, SrO, and BaO are all components that reduce glass viscosity and improve its meltability and formability. Furthermore, P2O5 is a component that greatly contributes to the low expansion of glass, and also increases glass viscosity and improves phase separation. The preferred ratio of (MgO + CaO + SrO + BaO) / P2O5 (the sum of the contents of MgO, CaO, SrO, and BaO divided by the P2O5 content) is 20% or less, 15% or less, 10% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4.5% or less, 4.4% or less, 4.3% or less, 4.2% or less, 4.1% or less, 4.0% or less, 3.9% or less, and particularly 3.8% or less. When the ratio of (MgO + CaO + SrO + BaO) / P2O5 is too high, the linear coefficient of thermal expansion becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Moreover, the homogeneity of the glass melt tends to decrease. On the other hand, when (MgO+CaO+SrO+BaO) / P2O5 is too small, the viscosity of the glass increases, the productivity decreases, and the manufacturing cost is likely to increase.

[0052] ZnO is a component that reduces glass viscosity and improves its melt and formability. It is also used to adjust the linear thermal expansion coefficient and refractive index of glass, and it can affect phase separation in glass. The ZnO content is preferably 0% or more, greater than 0%, 0.5% or more, 1% or more, particularly 5% or more, and preferably 20% or less, 18% or less, 17% or less, 15% or less, 14% or less, 13% or less, 12.5% ​​or less, particularly 11% or less. When the ZnO content is too high, phase separation easily occurs in the glass. Therefore, not only does the homogeneity of the molten glass tend to decrease, but there is also a tendency for the glass to unexpectedly become cloudy. Therefore, especially in order to suppress glass phase separation and control the risk of glass cloudiness, the ZnO content is preferably 3% or less, 2% or less, 1% or less, or 0.5% or less, and particularly preferably free of this component.

[0053] SnO2 acts as a clarifying agent, adjusts the linear thermal expansion coefficient and refractive index of glass, and affects phase separation. The preferred SnO2 content is 0% or more, greater than 0%, 0.0001% or more, 0.001% or more, 0.005% or more, 0.01% or more, 0.03% or more, 0.05% or more, 0.1% or more, and particularly 0.15% or more. There is no specific upper limit for SnO2 content, but in practice it is 20%. When the content exceeds 20%, Sn-containing devitrifying agents precipitate, easily increasing the manufacturing load. Furthermore, excessive SnO2 content leads to an excessively high linear thermal expansion coefficient, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Moreover, the homogeneity of the glass melt tends to decrease. Additionally, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance.

[0054] ZrO2 is a component that improves the Young's modulus and rigidity modulus of glass, and is also used to adjust the coefficient of thermal expansion or refractive index, and can affect phase separation in glass. The ZrO2 content is preferably 0% or more, greater than 0%, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, 0.005% or more, 0.006% or more, 0.007% or more, 0.008% or more, 0.009% or more, 0.01% or more, 0.02% or more, 0.03% or more, 0.04% or more, 0.05% or more, 0.06% or more, 0.07% or more, 0.08% or more, 0.09% or more, 0.1% or more, 1% or more, 2% or more, particularly 3% or more, and preferably 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, particularly 6% or less. Excessive ZrO2 content increases devitrification, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, it not only reduces the homogeneity of the molten glass, making it difficult to melt and increases viscosity, but also makes glass forming difficult, resulting in lower yield. Additionally, ZrO2 is easily introduced as an impurity; therefore, completely removing ZrO2 tends to increase the price of raw materials, leading to higher manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of ZrO2 content is preferably 0.0001% or more, 0.001% or more, and particularly 0.01% or more.

[0055] HfO2 is a component that increases the Young's modulus and rigidity modulus of glass, and it also reduces the viscosity of glass and improves its meltability and formability. Furthermore, it affects phase separation in glass. It is preferable to control the HfO2 content according to the present invention for the intended use of the glass, designing it in a way that achieves the desired mechanical strength. When the HfO2 content is too high, the mechanical strength of the glass becomes excessively high, making it difficult to process, and making it difficult to obtain glass with the desired surface condition and high transmittance. Moreover, HfO2 is expensive, increasing manufacturing costs. Based on the above, the HfO2 content is preferably 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, and particularly 0.2% or less. Furthermore, the lower limit of the HfO2 content is not particularly limited and can be 0% or more, but HfO2 is a component that may be mixed in from the raw materials used, and its mixing amount varies depending on the composition of the raw materials. Therefore, in reality, HfO2 can contain more than 0.0001%, more than 0.0003%, and especially more than 0.0005%.

[0056] Y₂O₃ is a component that reduces glass viscosity and improves glass meltability and formability. It is also used to increase the Young's modulus, adjust the linear thermal expansion coefficient and refractive index of glass, and affects phase separation in glass. The Y₂O₃ content is preferably 0% or more, greater than 0%, particularly 0.1% or more, preferably 30% or less, 20% or less, particularly 10% or less. When the Y₂O₃ content is too high, the linear thermal expansion coefficient becomes excessively high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt tends to decrease. Additionally, the chemical durability of the glass decreases, and the glass surface is prone to deterioration. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. Moreover, Y₂O₃ is easily introduced as an impurity; therefore, if Y₂O₃ is to be completely removed, there is a tendency for the price of raw materials to increase, leading to increased manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of the Y₂O₃ content is preferably 0.0001% or more, 0.001% or more, particularly 0.01% or more.

[0057] Pt is a component that can mix into glass in ionic, colloidal, or metallic states, causing a yellow to brownish-yellow color, and it also affects phase separation in glass. The Pt content is preferably 0.05% or less, 0.001% or less, 0.0005% or less, 0.0001% or less, 0.00005% or less, 0.00001% or less, and particularly 0.000005% or less. Excessive Pt content can lead to the precipitation of Pt-containing devitrifying substances, easily increasing the manufacturing load. Furthermore, while there is no particular limitation on the lower limit of Pt content, it can be 0%, but when using conventional melting equipment, Pt components are sometimes necessary to obtain homogeneous glass. Therefore, if Pt is to be completely removed, there is a tendency to increase manufacturing costs. To suppress the increase in manufacturing costs without adversely affecting coloring, the lower limit of Pt content is preferably greater than 0%, greater than 0.0000001%, and particularly greater than 0.0000005%.

[0058] Rh is a component that can mix into glass in ionic, colloidal, or metallic states, causing a yellow to brownish-yellow color, and can also affect phase separation in glass. The Rh content is preferably 0.05% or less, 0.001% or less, 0.0005% or less, 0.0001% or less, 0.00005% or less, 0.00001% or less, and particularly 0.000005% or less. Excessive Rh content can lead to the precipitation of Rh-containing devitrifying substances, easily increasing the manufacturing workload. Furthermore, while there is no particular limitation on the lower limit of Rh content, which can be 0%, Rh components are sometimes necessary to obtain homogeneous glass when using conventional melting equipment. Therefore, completely removing Rh tends to increase manufacturing costs. To suppress the increase in manufacturing costs without adversely affecting coloring, the lower limit of Rh content is preferably greater than 0%, greater than 0.0000001%, and particularly greater than 0.0000005%.

[0059] Furthermore, the total content of Pt + Rh (the sum of Pt and Rh content) is preferably 0.01% or less, 0.005% or less, 0.001% or less, 0.0005% or less, 0.0001% or less, 0.00005% or less, 0.00001% or less, and particularly 0.000005% or less. While the lower limit of Pt + Rh is not particularly limited and can be 0%, in the case of using conventional melting equipment, it is sometimes necessary to use Pt or Rh components to obtain homogeneous glass. Therefore, if Pt and Rh are to be completely removed, there is a tendency for manufacturing costs to increase. To suppress the increase in manufacturing costs without adversely affecting coloring, the lower limit of Pt + Rh is preferably greater than 0%, greater than 0.0000001%, and particularly greater than 0.0000005%.

[0060] V₂O₅ is a component that, when present in appropriate amounts, reduces glass viscosity and improves its meltability and formability. It is also a coloring component in glass that absorbs light of various wavelengths and can affect phase separation in glass. The preferred V₂O₅ content is below 20,000 ppm, below 10,000 ppm, less than 7,000 ppm, below 6,000 ppm, below 5,000 ppm, below 4,000 ppm, below 3,000 ppm, below 2,000 ppm, below 1,000 ppm, below 500 ppm, below 300 ppm, below 100 ppm, and especially below 50 ppm. Excessive V₂O₅ content can easily reduce the meltability of the glass. Furthermore, the glass is prone to coloring, making it difficult to obtain the desired high transmittance. However, V₂O₅ is easily introduced as an impurity; therefore, completely removing V₂O₅ can lead to increased raw material prices and thus increased manufacturing costs. To suppress increased manufacturing costs, the lower limit of V₂O₅ content is preferably greater than 0, above 1 ppm, above 2 ppm, and especially above 3 ppm. Furthermore, the transmittance can be adjusted by controlling the V2O5 content according to the application of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for cookware top plates, the V2O5 content can be set to 100 ppm or more, 500 ppm or more, 1000 ppm or more, 2000 ppm or more, 2500 ppm or more, 3000 ppm or more, 4000 ppm or more, 5000 ppm or more, 6000 ppm or more, 7000 ppm or more, and especially 7500 ppm or more.

[0061] Cr2O3 is a component that reduces glass viscosity and improves glass meltability and formability. It is also a coloring component in glass that absorbs light of various wavelengths and affects phase separation in glass. The preferred Cr2O3 content is below 20,000 ppm, below 10,000 ppm, less than 7,000 ppm, below 6,000 ppm, below 5,000 ppm, below 4,000 ppm, below 3,000 ppm, below 2,000 ppm, below 1,000 ppm, below 500 ppm, below 300 ppm, below 100 ppm, and especially below 50 ppm. Excessive Cr2O3 content makes the glass prone to coloring, making it difficult to obtain the desired high transmittance. Furthermore, Cr-containing devitrifying substances precipitate, easily increasing the manufacturing load. Additionally, the transmittance can be adjusted by controlling the Cr2O3 content according to the application of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for the top plate of a cooking appliance, the Cr2O3 content can be set to 100ppm or more, 500ppm or more, 800ppm or more, 1000ppm or more, 2000ppm or more, and especially 3000ppm or more.

[0062] Cr2O3 and V2O5 are components that, when present in appropriate amounts, reduce glass viscosity and improve its meltability and formability. They are also coloring components in glass that absorb light of various wavelengths. In applications such as cookware tops where a black appearance is required, the inclusion of multiple coloring components can be considered. Cr2O3 and V2O5 are components that particularly facilitate the blackening of glass, further enhancing its blackness. Therefore, to improve the blackness of glass, the combined content of Cr2O3 + V2O5 (the sum of Cr2O3 and V2O5 content) is preferably 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, 3000 ppm or more, 6000 ppm or more, and especially 9000 ppm or more. However, when the Cr2O3+V2O5 content is too high, the meltability of the glass is easily reduced. Therefore, the Cr2O3+V2O5 content is preferably below 200,000 ppm, below 100,000 ppm, below 50,000 ppm, below 30,000 ppm, below 20,000 ppm, and especially below 10,000 ppm.

[0063] MoO3 is a component that reduces glass viscosity and improves glass meltability and formability. It is also a coloring component of glass that absorbs light of various wavelengths and affects phase separation in glass. The preferred MoO3 content is 20,000 ppm or less, 10,000 ppm or less, less than 7,000 ppm, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, and especially 50 ppm or less. When the MoO3 content is too high, the glass is easily colored, making it difficult to obtain the desired high transmittance. Furthermore, the precipitation of Mo-containing devitrifying substances can easily increase the manufacturing load. In addition, the transmittance can be adjusted by controlling the MoO3 content according to the intended use of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for cookware top plates, the MoO3 content can be set to 100 ppm or more, 500 ppm or more, 800 ppm or more, 1,000 ppm or more, 2,000 ppm or more, and especially 3,000 ppm or more.

[0064] MnO2 is a component that reduces glass viscosity and improves glass meltability and formability when present in appropriate amounts. It is also a coloring component in glass that absorbs light of various wavelengths and affects phase separation in glass. The preferred MnO2 content is below 20,000 ppm, below 10,000 ppm, below 7,000 ppm, below 6,000 ppm, below 5,000 ppm, below 4,000 ppm, below 3,000 ppm, below 2,000 ppm, below 1,000 ppm, below 500 ppm, below 300 ppm, below 100 ppm, and especially below 50 ppm. Excessive MnO2 content can easily reduce the meltability of the glass. Furthermore, the glass is prone to coloring, making it difficult to obtain the desired high transmittance. However, MnO2 is easily introduced as an impurity; therefore, completely removing MnO2 can lead to increased raw material prices and thus increased manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of the MnO2 content is preferably greater than 0 ppm, above 1 ppm, above 2 ppm, and especially above 3 ppm. Furthermore, the transmittance can be adjusted by controlling the MnO2 content according to the application of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for cookware top plates, the MnO2 content can be set to 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, and especially 3000 ppm or more.

[0065] CoO is a component that, when present in appropriate amounts, reduces glass viscosity and improves its meltability and formability. It is also a coloring component in glass that absorbs light of various wavelengths and can affect phase separation in glass. The preferred CoO content is below 20,000 ppm, 10,000 ppm, 7,000 ppm, 6,000 ppm, 5,000 ppm, 4,000 ppm, 3,000 ppm, 2,000 ppm, 1,000 ppm, 500 ppm, 300 ppm, 100 ppm, and especially below 50 ppm. Excessive CoO content can easily reduce the meltability of the glass. Furthermore, the glass is prone to coloring, making it difficult to obtain the desired high transmittance. However, CoO is easily introduced as an impurity; therefore, completely removing CoO can lead to increased raw material costs and thus higher manufacturing costs. To suppress increased manufacturing costs, the lower limit of the CoO content is preferably greater than 0 ppm, 1 ppm or more, 2 ppm or more, and especially 3 ppm or more. Additionally, the transmittance can be adjusted by controlling the CoO content according to the application of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for the top plate of a cooking appliance, the CoO content can be set to 100ppm or more, 500ppm or more, 800ppm or more, 1000ppm or more, 2000ppm or more, and especially 3000ppm or more.

[0066] CuO is a component that, when present in appropriate amounts, reduces the viscosity of glass and improves its meltability and formability. It is also a coloring component in glass that absorbs light of various wavelengths and can affect phase separation in glass. The preferred CuO content is 20,000 ppm or less, 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, and especially 50 ppm or less. Excessive CuO content can easily reduce the meltability of the glass. Furthermore, the glass is prone to coloring, making it difficult to obtain the desired high transmittance. However, CuO is easily introduced as an impurity; therefore, completely removing CuO can lead to increased raw material costs and thus higher manufacturing costs. To suppress the increase in manufacturing costs, the lower limit of the CuO content is preferably greater than 0 ppm, 1 ppm or more, 2 ppm or more, and especially 3 ppm or more. Additionally, the transmittance can be adjusted by controlling the CuO content according to the application of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for the top plate of a cooking appliance, the CuO content can be set to 100ppm or more, 500ppm or more, 800ppm or more, 1000ppm or more, 2000ppm or more, and especially 3000ppm or more.

[0067] Nd₂O₃ is a component that reduces glass viscosity and improves its meltability and formability when present in appropriate amounts. It is also a coloring component in glass that absorbs light of various wavelengths and can affect phase separation in glass. The preferred Nd₂O₃ content is 20,000 ppm or less, 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, and especially 50 ppm or less. When the Nd₂O₃ content is too high, the glass is easily colored, making it difficult to obtain the desired high transmittance. Furthermore, the transmittance can be adjusted by controlling the Nd₂O₃ content according to the intended use of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for cookware top plates, the Nd₂O₃ content can be set to 100 ppm or more, 500 ppm or more, 800 ppm or more, 1,000 ppm or more, 2,000 ppm or more, and especially 3,000 ppm or more.

[0068] WO3 is a component that reduces glass viscosity and improves its melt and formability by being present in appropriate amounts. It is also a coloring component in glass that absorbs light of various wavelengths and can affect phase separation in glass. The preferred WO3 content is below 20,000 ppm, 10,000 ppm, 7,000 ppm, 6,000 ppm, 5,000 ppm, 4,000 ppm, 3,000 ppm, 2,000 ppm, 1,000 ppm, 500 ppm, 300 ppm, 100 ppm, and especially below 50 ppm. Excessive WO3 content can easily color the glass, making it difficult to obtain the desired high transmittance. Furthermore, the transmittance can be adjusted by controlling the WO3 content according to the intended use of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for cookware tops, the WO3 content can be set to 100 ppm or more, 500 ppm or more, 800 ppm or more, 1,000 ppm or more, 2,000 ppm or more, and especially 3,000 ppm or more.

[0069] NiO is a component that, when present in appropriate amounts, reduces glass viscosity and improves its meltability and formability. It is also a coloring component in glass that absorbs light of various wavelengths and affects phase separation in glass. The preferred NiO content is 20,000 ppm or less, 10,000 ppm or less, 7,000 ppm or less, 6,000 ppm or less, 5,000 ppm or less, 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 100 ppm or less, and especially 50 ppm or less. Excessive NiO content tends to reduce the meltability of the glass. Furthermore, the glass is easily colored, making it difficult to obtain the desired high transmittance. However, NiO can easily be introduced from components such as SUS parts during the manufacturing process, so completely removing NiO can lead to higher raw material prices and increased manufacturing costs. To suppress increased manufacturing costs, the lower limit of NiO content is preferably greater than 0 ppm, 1 ppm or more, 2 ppm or more, and especially 3 ppm or more. Furthermore, the transmittance can be adjusted by controlling the NiO content according to the application of the glass according to the present invention. For example, in cases where a colored appearance is required, such as for cookware top plates, the NiO content can be set to 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, and especially 3000 ppm or more.

[0070] As₂O₃ and Sb₂O₃ are highly toxic and may pollute the environment during glass manufacturing processes or waste glass disposal. Therefore, the total content of Sb₂O₃ + As₂O₃ (the sum of Sb₂O₃ and As₂O₃ content) is preferably below 20,000 ppm, below 10,000 ppm, less than 7,000 ppm, below 6,000 ppm, below 5,000 ppm, below 4,000 ppm, below 3,000 ppm, below 2,000 ppm, below 1,000 ppm, below 500 ppm, below 300 ppm, below 100 ppm, below 10 ppm, below 5 ppm, below 1 ppm, and especially below 1 ppm.

[0071] The glass of the present invention, in order to achieve the desired chemical durability, transmittance, heat resistance, and thermal shock resistance, may contain, in addition to the aforementioned components, SO3, Cl2, La2O3, Ta2O5, Nb2O5, RfO2, etc., in a total content of no more than 10%. However, the raw material prices of the above-mentioned components are high, and there is a trend of increased manufacturing costs. Therefore, except in special cases, they may not be added. The total content of these components, in mass percent, is preferably 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, 0.05% or less, less than 0.05%, 0.049% or less, 0.048% or less, 0.047% or less, 0.046% or less, and particularly 0.045% or less.

[0072] The glass of the present invention, in order to achieve the desired chemical durability, transmittance, heat resistance, and thermal shock resistance, may contain trace components such as H2, CO2, CO, H2O, He, Ne, Ar, and N2, in addition to the aforementioned components, at amounts of 0.1% or less. Furthermore, the active addition of Ag, Au, Pd, Ir, Sc, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, and U increases raw material costs, resulting in increased manufacturing costs. However, Pd and the like possess various catalytic effects, and the inclusion of these components can impart special functions to the glass. In view of this, when the purpose is to promote crystallization or impart other functions, the aforementioned components may be contained at amounts of 1% or less, 0.5% or less, 0.3% or less, or 0.1% or less, respectively; when these purposes are not particularly required, amounts of 500 ppm or less, 300 ppm or less, 100 ppm or less, and particularly 10 ppm or less are preferred.

[0073] Furthermore, the glass of the present invention can be a crystallized glass. In this case, the content range of each component is the same as above. Examples of seed crystals in crystallized glass include Al2SiO5 and ZrO2.

[0074] When implementing the glass of the present invention, the preferred composition range, in mass %, is, for example, SiO2: 45-80%, Al2O3: 10-30%, B2O3: greater than 0 and less than 8%, Li2O: 0-3%, TiO2: greater than 0 and less than 20%, and P2O5: 6.5-20%.

[0075] The glass of the present invention having the above composition readily achieves a low coefficient of linear expansion and excellent light transmittance.

[0076] Furthermore, when the glass of the present invention is a crystallized glass, by having the above-described composition, it is easy to achieve a low coefficient of linear expansion and excellent light transmittance.

[0077] The density of the glass of the present invention is preferably 2.20 to 3.50 g / cm³. 3 2.30~3.40g / cm 3 2.40~3.35g / cm 3 2.50~3.30g / cm 3 Especially 2.55–3.25 g / cm³ 3 If the density is too low, the glass becomes more permeable to air, and it may become contaminated during long-term storage. If the density is too high, the weight per unit area increases, making handling difficult.

[0078] The β-OH value of the glass of the present invention is preferably greater than 0 and is less than 2 / mm, 0.001 to 2 / mm, 0.01 to 1.5 / mm, 0.02 to 1.5 / mm, 0.03 to 1.2 / mm, 0.04 to 1.5 / mm, 0.05 to 1.4 / mm, 0.06 to 1.3 / mm, 0.07 to 1.2 / mm, 0.08 to 1.1 / mm, 0.08 to 1 / mm, 0.08 to 0.9 / mm, 0.08 to 0.85 / mm, 0.08 to 0.8 / mm, 0.08 to 0.75 / mm, 0.08 to 0.74 / mm, 0.08 to 0.73 / mm, 0.08 to 0.72 / mm, 0.08 to 0.71 / mm, and particularly 0.08 to 0.7 / mm. When the β-OH value is too low, the amount of water vapor generated during the melting of the glass batch decreases. Therefore, the stirring effect on the glass batch due to water vapor generation is weakened, making it difficult to promote the initial reaction of the glass batch, and easily increasing the manufacturing load. Conversely, when the β-OH value is too high, bubbles are easily generated at the interface between metal parts (such as Pt) or refractory parts and the molten glass, easily reducing the quality of the glass products. Furthermore, the glass transition temperature, yield point, strain point, annealing point, and softening point may decrease, and the linear thermal expansion coefficient may increase, leading to poor heat resistance and thermal shock resistance, thus making it unsuitable for use at high temperatures. In addition, the β-OH value varies depending on the raw materials used, the melting atmosphere, the melting temperature, and the melting time; therefore, these conditions can be changed to adjust the β-OH value as needed. For example, increasing the amount of hydroxide in the raw materials, using a burner for melting, or increasing the melting temperature can increase the β-OH value. Moreover, extending the melting time in a closed environment and shortening the melting time in a non-closed environment can also increase the β-OH value.

[0079] The linear thermal expansion coefficient of the glass of the present invention at 30–380°C is preferably 60 × 10⁻⁶. －7 / ℃ below, 56×10 －7 / ℃ below, 52×10 －7 / ℃ below, 48×10 －7 / ℃ below, 44×10 －7 / ℃ below, 40×10 －7 / ℃ below, 36×10 －7 / ℃ below, 34×10 －7 / ℃ below, 32×10 －7 / ℃ below, 29.5×10 －7 / ℃ below, 27.5×10 －7 / ℃ below, 25.5×10 －7 / ℃ below, 23.5×10 －7 / ℃ below, 21.5×10 －7 / ℃ below, 19.5×10 －7 / ℃ below, 18×10 －7 / ℃ below, 17.5×10 －7 / ℃ below, 17×10 －7 / ℃ below, 16.5×10 －7 / ℃ below, 15.5×10 －7 / ℃ below, 15×10 －7 / ℃ below, 14.5×10 －7 / ℃ below, 14×10 －7 Below / ℃, especially 13.5×10 －7 / ℃ below.

[0080] Furthermore, the linear coefficient of thermal expansion of the glass of the present invention at temperatures ranging from 30 to 750°C is preferably 60 × 10⁻⁶. －7 / ℃ below, 56×10 －7 / ℃ below, 52×10 －7 / ℃ below, 48×10 －7 / ℃ below, 44×10 －7 / ℃ below, 40×10 －7 / ℃ below, 36×10 －7 / ℃ below, 34×10 －7 / ℃ below, 32×10 －7 / ℃ below, 29.5×10 －7 / ℃ below, 27.5×10 －7 / ℃ below, 25.5×10 －7 / ℃ below, 23.5×10 －7 / ℃ below, 21.5×10 －7 / ℃ below, 19.5×10 －7 / ℃ below, 18×10 －7 / ℃ below, 17.5×10 －7 / ℃ below, 17×10 －7 / ℃ below, 16.5×10 －7 / ℃ below, 15.5×10 －7 / ℃ below, 15×10 －7 / ℃ below, 14.5×10 －7 / ℃ below, 14×10 －7 Below / ℃, especially 13.5×10 －7 / ℃ below.

[0081] When the linear coefficient of thermal expansion is too high, heat resistance and thermal shock resistance are low, making it difficult to use at high temperatures. Furthermore, it is unsuitable for applications requiring positional stability. Especially when envisioned for use as a top plate in cooking appliances, a lower linear coefficient of thermal expansion is preferred to avoid breakage due to heat or strain. While there is no particular lower limit to the linear coefficient of thermal expansion, in reality, the linear coefficient of thermal expansion between 30 and 380°C is -70 × 10⁻⁶. －7 The linear thermal expansion coefficient at temperatures above ℃ and between 30 and 750℃ is -60 × 10⁻⁶. －7 / ℃ or above.

[0082] In the glass of this invention, the temperature at which the slope of the glass's thermal expansion curve changes is considered the glass transition temperature (glass transition point). The glass transition temperature of the glass of this invention is preferably 710°C or higher, 712°C or higher, 714°C or higher, 716°C or higher, 718°C or higher, 720°C or higher, 722°C or higher, 724°C or higher, 726°C or higher, 728°C or higher, and particularly 730°C or higher. If the glass transition temperature is too low, the glass flows excessively and is difficult to form into the desired shape. Conversely, if the glass transition temperature is too low, the glass is prone to deformation when used at high temperatures.

[0083] In the glass of the present invention, the temperature at which the slope of the thermal expansion curve of the glass changes above the glass transition temperature is considered the yield point. The yield point of the glass of the present invention is preferably 750°C or higher, 752°C or higher, 754°C or higher, 758°C or higher, 762°C or higher, 764°C or higher, 766°C or higher, 768°C or higher, and particularly 770°C or higher. If the yield point is too low, the glass flows excessively and is difficult to form into the desired shape. Conversely, if the yield point is too low, the glass is prone to deformation when used at high temperatures.

[0084] The liquidus temperature of the glass of the present invention is preferably below 1600°C, 1580°C, 1560°C, 1540°C, 1520°C, 1500°C, 1480°C, 1460°C, 1440°C, 1420°C, 1410°C, 1400°C, 1380°C, 1360°C, 1340°C, 1320°C, 1300°C, 1290°C, 1280°C, 1270°C, 1260°C, 1250°C, 1240°C, 1230°C, 1200°C, 1190°C, and particularly below 1180°C. When the liquidus temperature is too high, devitrification is prone to occur during manufacturing. On the other hand, if the temperature is below 1480°C, it is easy to manufacture using methods such as roll forming; if the temperature is below 1410°C, it is easy to manufacture using methods such as overflow forming; if the temperature is below 1350°C, it is easy to manufacture using methods such as perforated forming; and if the temperature is below 1300°C, it is easy to manufacture using methods such as the danner process.

[0085] The liquid phase viscosity (logarithm of viscosity corresponding to liquid phase temperature) of the glass of the present invention is preferably 1.6 or higher, 1.70 or higher, 1.75 or higher, 1.80 or higher, 1.85 or higher, 1.90 or higher, 1.95 or higher, 2.00 or higher, 2.05 or higher, 2.10 or higher, 2.15 or higher, 2.20 or higher, 2.25 or higher, 2.30 or higher, 2.35 or higher, 2.40 or higher, 2.45 or higher, 2.50 or higher, 2.55 or higher, 2 0.60 and above, 2.65 and above, 2.70 and above, 2.75 and above, 2.80 and above, 2.85 and above, 2.90 and above, 2.95 and above, 3.00 and above, 3.05 and above, 3.10 and above, 3.15 and above, 3.20 and above, 3.25 and above, 3.30 and above, 3.35 and above, 3.40 and above, 3.45 and above, 3.50 and above, 3.55 and above, 3.60 and above, 3.65 and above, especially 3.70 and above. When the liquid phase viscosity is too low, devitrification is prone to occur during manufacturing. On the other hand, if it is above 3.40, it is easier to manufacture using methods such as rolling; if it is above 3.50, it is easier to manufacture using methods such as molding; if it is above 3.70, it is easier to manufacture using methods such as overflow.

[0086] In applications requiring high transmittance in the infrared region, the glass of the present invention preferably has a transmittance of 0.1% or more, 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 81% or more, 83% or more, 85% or more, 86% or more, 87% or more, and particularly 88% or more, when it has a thickness of 4 mm and a wavelength of 1200 nm. Especially in applications requiring high transmittance in the infrared region, the transmittance of 4 mm and a wavelength of 1200 nm is preferably 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less, when it has a thickness of 4 mm and a wavelength of 1200 nm. Especially in applications requiring infrared light blocking, the transmittance of 1200 nm is preferably low. However, the suitable transmittance varies depending on the application and is not limited to the specific numerical range mentioned above.

[0087] In applications requiring high transmittance in the near-infrared region, the glass of the present invention preferably has a transmittance of 0.1% or more, 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 84% or more, 85% or more, 86% or more, 87% or more, and particularly 88% or more, when it has a thickness of 4 mm and a wavelength of 800 nm. Especially in medical applications such as vein authentication, high transmittance at a wavelength of 800 nm is preferred. On the other hand, in applications requiring low transmittance in the near-infrared region, a transmittance of 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less, when it has a thickness of 4 mm and a wavelength of 800 nm, is preferred. Especially in applications such as chemical containers, visible light shielding, or cooktops requiring a colored appearance, a low transmittance at a wavelength of 800 nm is preferred. However, suitable transmittance varies depending on the application and is not limited to the specific numerical range mentioned above.

[0088] In applications requiring high transmittance in the visible light region, the glass of the present invention preferably has a transmittance of 0.1% or more, 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 84% or more, 85% or more, 86% or more, 87% or more, and particularly 88% or more, at a thickness of 4 mm and a wavelength of 555 nm. The wavelength range around 555 nm is a region where humans easily perceive light as brightness, and high transmittance at 555 nm is particularly desirable in applications requiring high brightness, such as displays. On the other hand, in applications requiring low transmittance in the visible light region, a transmittance of 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less, at a thickness of 4 mm and a wavelength of 555 nm, is preferred. Especially in applications such as chemical containers, UV-green light shielding, or cooking appliance tops requiring a colored appearance, a low transmittance at a wavelength of 555 nm is preferred. However, suitable transmittance varies depending on the application and is not limited to the specific numerical range mentioned above.

[0089] In applications requiring high transmittance in the near-ultraviolet region, the glass of the present invention preferably has a transmittance of 0.1% or more, 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 36% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 83% or more, and particularly 84% or more, at a thickness of 4 mm and a wavelength of 380 nm. Especially in applications requiring colorless transparency, such as displays, high transmittance at a wavelength of 380 nm is preferred. If the transmittance at a wavelength of 380 nm is too low, the glass is prone to yellowing, making it difficult to obtain the desired colorless transparency. On the other hand, in applications requiring low transmittance in the near-ultraviolet region, the transmittance at a thickness of 4 mm and a wavelength of 380 nm is preferably 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less. Especially in applications such as chemical containers, UV- to blue light shielding, or cooking appliance tops requiring a colored appearance, a low transmittance at a wavelength of 380 nm is preferred. However, suitable transmittance varies depending on the application and is not limited to the specific numerical range mentioned above.

[0090] The transmittance of the glass of the present invention should be appropriately controlled for each wavelength according to the application. Specifically, in applications requiring high transmittance in the ultraviolet region, a transmittance of 0.1% or more, 1% or more, 5% or more, 10% or more, 20% or more, 24% or more, 28% or more, 30% or more, 40% or more, 43% or more, 44% or more, and particularly 45% or more is preferred when the glass is 4 mm thick and has a wavelength of 300 nm. High transmittance at 300 nm is particularly preferred for applications such as UV curing of resins, fluorescence detection of printed materials, and insect attraction. On the other hand, in applications requiring low transmittance in the ultraviolet region, a transmittance of 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less is preferred when the glass is 4 mm thick and has a wavelength of 300 nm. Low transmittance at 300 nm is particularly preferred when UV cutoff capability is required, such as in chemical containers or optical filters. However, the suitable transmittance varies depending on the application and is not limited to the specific numerical range mentioned above.

[0091] The brightness L of the glass of this invention ＊ Appropriate control should be exercised depending on the intended use. For applications requiring high brightness, a thickness of 4mm is recommended for a brightness level of L. ＊ Preferably, values ​​of 5 or higher, 10 or higher, 20 or higher, 30 or higher, 40 or higher, 50 or higher, 60 or higher, 70 or higher, 80 or higher, 85 or higher, 90 or higher, 94 or higher, 95 or higher, 96 or higher, 96.1 or higher, 96.3 or higher, and especially 96.5 or higher. In terms of brightness (L)... ＊ When the brightness is too low, it tends to appear grayish and dark regardless of the chromaticity level. Therefore, especially in applications requiring high brightness such as monitors, a brightness level of L is preferred. ＊ Large. On the other hand, in applications requiring low brightness, a thickness of 4mm is suitable for brightness levels of L. ＊ Preferably, the lightness level is 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, and especially 10 or less. Particularly in cases where it is used for chemical containers or visible light shielding applications, or where a black appearance is required for cookware tops, a lightness level of L is preferred. ＊ Low. But suitable brightness L ＊ The values ​​vary depending on the intended use and are not limited to the specific numerical ranges mentioned above.

[0092] Regarding the glass of the present invention, in applications requiring high colorless transparency, the chromaticity a at a thickness of 4 mm is... ＊Preferably within ±50, ±40, ±30, ±20, ±10, ±5, ±3, ±1, ±0.9, ±0.8, ±0.7, ±0.6, and especially within ±0.5. A chromaticity a exists. ＊ There's a tendency for the color to appear greenish when too large in the negative direction and reddish when too large in the positive direction. On the other hand, when a deep green or red hue is needed, the chromaticity a at a thickness of 4mm... ＊ Preferably, the values ​​are ±6 or higher, ±7 or higher, ±8 or higher, and especially ±9 or higher. Additionally, when the color is black, the chromaticity a at a thickness of 4 mm is... ＊ Preferably, the values ​​are +10 or higher, +12 or higher, +14 or higher, +16 or higher, +17 or higher, +18 or higher, +19 or higher, and especially +20 or higher. However, the suitable chromaticity a... ＊ The values ​​vary depending on the intended use and are not limited to the specific numerical ranges mentioned above.

[0093] Regarding the glass of the present invention, in applications requiring high colorless transparency, the chromaticity b at a thickness of 4 mm... ＊ Preferably within ±50, ±45, ±40, ±30, ±20, ±10, ±5, ±3, ±1, ±0.9, ±0.8, ±0.7, ±0.6, and especially within ±0.5. A chromaticity b exists. ＊ There's a tendency for the color to appear bluish when too large in the negative direction and yellowish when too large in the positive direction. On the other hand, when a deep blue or yellow hue is needed, the color saturation b at a thickness of 4mm... ＊ Preferably, the values ​​are ±6 or higher, ±7 or higher, ±8 or higher, and especially ±9 or higher. Additionally, when the color is black, the chromaticity b at a thickness of 4 mm... ＊ Preferably, the values ​​are +10 or higher, +12 or higher, +16 or higher, +20 or higher, +24 or higher, +28 or higher, +32 or higher, +36 or higher, +40 or higher, +42 or higher, +44 or higher, +46 or higher, +48 or higher, and especially +50 or higher. However, the suitable chromaticity b... ＊ The values ​​vary depending on the intended use and are not limited to the specific numerical ranges mentioned above.

[0094] When the glass of the present invention is in the form of a plate, the average surface roughness Ra of its main surface is preferably 50 nm or less, 25 nm or less, 15 nm or less, 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, and particularly 1 nm or less. When the surface roughness Ra is too large, light incident on the glass surface from the outside is easily scattered, and light is difficult to escape from the inside of the glass to the outside, making it difficult to obtain the glass with the required high transmittance. Moreover, the glass is easily broken. On the other hand, when the surface roughness Ra of the planar surface is too small, the glass surface is easily charged, and the attraction between the glass and the object in contact with the glass surface increases, sometimes making it difficult to obtain the required release properties. Moreover, due to the charge on the glass surface, it is sometimes difficult to obtain the required electrical responsiveness. In view of the above, the surface roughness Ra of the planar surface of the glass of the present invention is preferably 0.0001 nm or more, 0.001 nm or more, 0.01 nm or more, or 0.1 nm or more.

[0095] When the glass of the present invention is plate-shaped, the average surface roughness Ra of its end face is preferably 100 nm or less, 50 nm or less, 25 nm or less, 15 nm or less, 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, and particularly 1 nm or less. When the surface roughness Ra of the end face is too large, light is difficult to enter the glass from the glass end face and difficult to exit from the glass from the glass to the outside, making it difficult to obtain the glass with the required high transmittance. Moreover, the glass is easily broken. On the other hand, if the surface roughness Ra of the end face is too small, when it is desired to physically support the glass using the glass end face, the contact area between the glass and the support body becomes smaller or the frictional resistance becomes smaller, making reliable support difficult. In view of the above, the surface roughness Ra of the end face of the glass of the present invention is preferably 0.00001 nm or more, 0.0001 nm or more, 0.001 nm or more, 0.01 nm or more, or 0.1 nm or more.

[0096] The waviness of the glass of the present invention is preferably 10 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 0.8 μm or less, 0.7 μm or less, 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, 0.2 μm or less, 0.1 μm or less, 0.08 μm or less, 0.05 μm or less, 0.03 μm or less, 0.02 μm or less, and particularly 0.01 μm or less. When the waviness is too large, the incident angle of light incident on the glass surface at a specific location is easily distributed, and the amount of light scattered on the glass surface increases after averaging, making it difficult to obtain glass with the required high transmittance. The lower limit of the waviness is not particularly limited, but in practice it is 0.01 nm or more.

[0097] The surface roughness Ra of the main surface and end faces of the glass can be determined according to JIS B0601:2001. Additionally, the waviness can be determined using a stylus-type surface shape measuring device according to SEMI STD D15-1296 "Method for Determination of Surface Waviness of FPD Glass Substrates". The wall thickness can be determined using conventional devices such as digital vernier calipers or point-contact roughness testers.

[0098] Typically, during phase separation involving cycloid decomposition (where subsequent phases exist within the first phase with the highest volume fraction, resulting in continuous mixing), unevenness can easily occur on the glass surface due to differences in the chemical durability of each phase. Through in-depth research, the inventors of this invention discovered that by annealing the glass of this invention at a temperature above the glass transition temperature, phase separation into two or more different phases is possible. In many cases, this phase separation is characterized by bicyclic decomposition (where subsequent phases are dispersed within the first phase with the highest volume fraction, and are mixed in spherical or similar shapes). Furthermore, it was found that by appropriately controlling the glass composition or annealing conditions, the phase separation exhibited by bicyclic decomposition can be selectively achieved, allowing for the refinement of a glass surface with the desired transmittance. Based on the above, the glass of this invention can be composed of only a single glass phase or can contain two or more phases. Additionally, for example, when a white or milky white appearance is required for use as a cooking top plate, the glass of this invention is particularly preferably in a state containing two or more phases. In this case, by appropriately controlling the annealing conditions, a white or milky-white glass can be easily obtained. Furthermore, the phases after the second phase can be in any state, including glass, crystalline, gaseous, and liquid states. Moreover, the phases after the second phase can be composed of metal oxides, metals, organic compounds, etc., and there are no limitations on the composition. In addition, the shape of the phases after the second phase is preferably plate-like, granular, spherical, circular, elliptical, or linear, and can be a single shape or a combination of these shapes. Furthermore, the phase separation can be determined by etching with a liquid such as hydrofluoric acid and then measuring the surface shape using SEM (scanning electron microscopy) or AFM (atomic force microscopy). Furthermore, the state of chemical bonds in the sample can be confirmed using FT-IR spectroscopy or Raman spectroscopy, obtaining information about phase separation in a non-destructive manner. The phase separation states described in this specification can be determined by methods readily conceived by those skilled in the art.

[0099] Regarding the size of the phases after the second phase, the longest portion of each is preferably 100 μm or less, 50 μm or less, 30 μm or less, 10 μm or less, 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 0.5 μm or less, 0.3 μm or less, 0.2 μm or less, and particularly 0.1 μm or less. When the longest portion of the phases after the second phase is too long, the surface roughness of the glass increases, making it difficult to obtain glass with the desired high transmittance. Furthermore, the lower limit of the longest portion of each phase after the second phase is not particularly limited, but in practice it is 0.01 nm or more.

[0100] When the phases after the second phase are crystalline, the preferred crystal system is any one of hexagonal, trigonal, cubic, tetragonal, orthorhombic, or monoclinic. While a triclinic system is also possible, birefringence easily occurs within the crystal, resulting in light scattering and making it difficult to obtain the desired high transmittance glass. In the case of a triclinic system, the composition of the first phase needs to be designed to minimize the refractive index difference between the crystal and the first phase.

[0101] In the case where the glass of the present invention comprises two or more phases, if the refractive index difference between the second and subsequent phases and the first phase is large, light will be scattered at the boundaries of each phase, making it difficult to obtain the desired high transmittance glass. The refractive index difference between the phases is preferably 1.5 at each of the representative wavelengths used in refractive index measurement: nd (587.6 nm), nC (656.3 nm), nF (486.1 nm), ne (546.1 nm), ng (435.8 nm), nh (404.7 nm), ni (365.0 nm), nF' (480.0 nm), n785 (785 nm), n1310 (1310 nm), and n1550 (1550 nm). Within 1.3, 1.1, 0.9, 0.7, 0.5, 0.3, 0.1, 0.09, 0.07, 0.05, 0.03, 0.01, 0.008, 0.006, 0.004, 0.002, 0.0009, 0.0007, 0.0005, 0.0003, 0.0002, and especially within 0.0001. The refractive index of each phase can be measured using a precision refractometer (Shimadzu Corporation KPR-2000).

[0102] The refractive index nd (587.6 nm) of the glass of the present invention is preferably 2.50 or less, 2.40 or less, 2.20 or less, 2.00 or less, 1.80 or less, 1.70 or less, 1.60 or less, 1.58 or less, 1.55 or less, 1.54 or less, and particularly 1.53 or less. Furthermore, it is preferably 1.20 or more, 1.25 or more, 1.30 or more, 1.35 or more, 1.38 or more, 1.40 or more, 1.42 or more, and particularly 1.43 or more. When the refractive index is too high, light may be scattered at the surface or end face, making it difficult to obtain the glass with the desired high transmittance. On the other hand, when the refractive index is too low, the refractive index difference between the glass of the present invention and air decreases, making it difficult to identify the glass of the present invention and making manufacturing operations difficult.

[0103] The glass of the present invention preferably has an unpolished surface. While glass has a very high theoretical strength, it often breaks under stresses far below its theoretical strength. This is because nanoscale defects known as Griffith flaws are generated on the glass surface during post-forming processes, such as polishing. Therefore, by making the surface of the glass of the present invention unpolished, its inherent mechanical strength is less likely to be compromised, and the glass is less prone to breakage. Furthermore, the polishing process can be omitted, thus reducing manufacturing costs. Additionally, for example, when the glass of the present invention is in sheet form, by making all effective surfaces of both main faces unpolished, the glass of the present invention is even less prone to breakage. Furthermore, an effective method to make all effective surfaces unpolished is to make the portions corresponding to the effective surfaces free surfaces during forming. Moreover, even if the portions corresponding to the effective surfaces come into contact with solid components during forming, a smooth surface similar to a free surface can be produced by reheating the portions in contact with solid components at a temperature above the glass transition temperature after forming.

[0104] The wall thickness of the glass of the present invention is preferably 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, and particularly 4 mm or less. When the wall thickness of the sample is too thick, the light attenuation rate inside the glass increases, making it difficult to obtain glass with the required high transmittance. Furthermore, when the glass of the present invention is used for display applications, the wall thickness is preferably 1000 μm or less, 500 μm or less, 200 μm or less, 100 μm or less, 70 μm or less, 50 μm or less, 30 μm or less, 1 to 20 μm, and particularly 5 to 10 μm.

[0105] The difference between the maximum and minimum thickness of the glass in this invention is preferably less than 50 μm, less than 25 μm, less than 10 μm, less than 5 μm, less than 1 μm, less than 500 nm, less than 300 nm, less than 100 nm, less than 50 nm, less than 25 nm, less than 15 nm, less than 10 nm, less than 9 nm, less than 8 nm, less than 7 nm, less than 6 nm, less than 5 nm, less than 4 nm, less than 3 nm, less than 2 nm, and particularly less than 1 nm. When the difference between the maximum and minimum thickness is too large, the incident angle of light incident from either the front or back side is different from the exit angle when it exits from the other side, resulting in unintended light scattering and easily creating a glare appearance.

[0106] The glass of the present invention preferably exhibits high water resistance as a representative chemical durability. Specifically, when the alkali leaching amount is determined according to the method of JIS R3502 (1995), the leaching amounts of Li2O, Na2O, and K2O are preferably 2 mg or less, 1.8 mg or less, 1.6 mg or less, 1.4 mg or less, 1.2 mg or less, 1.0 mg or less, 0.8 mg or less, 0.6 mg or less, 0.4 mg or less, 0.2 mg or less, 0.1 mg or less, 0.005 mg or less, and particularly 0.003 mg or less. When the water resistance is low, ion exchange between alkali metals and protons on the glass surface is more likely to occur, and the areas where ion exchange has taken place deteriorate, making them prone to cracking.

[0107] The glass of the present invention can be chemically strengthened. The conditions for chemical strengthening can be appropriately selected by considering the glass composition, the volume fraction of each phase, the type of molten salt, etc., and choosing the appropriate treatment time and temperature. For example, to facilitate chemical strengthening, a glass composition containing a large amount of Na₂O that can be contained in the residual glass phase can be selected. Furthermore, the molten salt can contain monovalent cations such as Li, Na, and K, or divalent cations such as Mg, Ca, Sr, Ba, and Zn, or multiple cations. Furthermore, not only conventional one-step strengthening but also multi-step chemical strengthening can be selected. Additionally, nitrates (potassium nitrate, sodium nitrate, lithium nitrate, etc.), carbonates (potassium carbonate, sodium carbonate, lithium carbonate, etc.), sulfates (potassium sulfate, sodium sulfate, lithium sulfate, etc.), chlorides (potassium chloride, sodium chloride, lithium chloride, etc.), or combinations thereof can be used as the molten salt. Among these, nitrates with low melting points are preferred as the molten salt, and sodium nitrate is particularly preferred. The preferred temperature for ion exchange is 330–550°C, 350–500°C, and especially 390–450°C, and the preferred time for ion exchange is 30 minutes–12 hours and 45 minutes–10 hours. Furthermore, the above-mentioned enhancement conditions can be arbitrarily changed according to the required application and intensity; suitable conditions are not limited to those described above.

[0108] When compressive stress is imparted to the glass of the present invention through chemical strengthening or the like, the compressive stress value (CS) is preferably 50 MPa or more, 100 MPa or more, 150 MPa or more, 200 MPa or more, 230 MPa or more, 260 MPa or more, and particularly 300 MPa or more. If the compressive stress value is too low, the Vickers hardness and flexural strength may decrease.

[0109] When compressive stress is applied to the glass of the present invention through chemical strengthening or the like, the depth of compressive stress (DOC) is preferably 10 μm or more, 50 μm or more, 100 μm or more, 110 μm or more, and particularly 120 μm or more. If the depth of compressive stress is too small, the breaking strength may decrease. The compressive stress value (CS) and the depth of compressive stress (DOC) can be measured using a scattered light photoelastic stress meter SLP-1000 (manufactured by Orihara Corporation) and a surface stress meter FSM-6000 (manufactured by Orihara Corporation).

[0110] The four-point bending strength of the glass of the present invention is preferably 150 MPa or more, 200 MPa or more, 235 MPa or more, 245 MPa or more, and particularly 250 MPa or more. If the four-point bending strength is too low, it is prone to breakage upon drop when used as a cover glass for smartphones, etc. Furthermore, there is no particular upper limit to the four-point bending strength; in practice, it is 1500 MPa or less. The four-point bending strength can be measured according to the following steps: First, with a glass plate processed to be 50 mm × 50 mm × 0.6 mm thick held vertically, a 1.5 mm thick SUS plate is attached to the main surface and the opposite surface of the glass plate, and the glass plate is fixed. Through P180 grit sandpaper, the tip of a pendulum-shaped arm is struck against it to apply damage. The tip of the arm is a φ5 mm iron cylinder, and the arm weight is 550 g. The downward swing height of the arm is set to 5 mm from the point of impact. The four-point bending strength is measured on the damaged glass plate.

[0111] Furthermore, when the glass of the present invention is a crystallized glass, it is also preferable to have the same characteristics as described above.

[0112] The glass of this invention is typically plate-shaped (especially flat), but is not limited thereto; the shape may be selected appropriately according to the application.

[0113] The method for manufacturing the glass of the present invention will be described below.

[0114] The glass manufacturing method of the present invention includes a step of melting glass raw materials to obtain molten glass, and a step of shaping the molten glass.

[0115] Specifically, firstly, a batch of raw material (glass raw material) prepared in the manner described above is fed into a glass melting furnace and melted at 1200–1800°C to obtain molten glass, which is then shaped. During glass melting, any one or a combination of two or more of the following methods can be used: flame melting using a burner, electric melting using electric heating, melting using laser irradiation, melting using plasma, liquid-phase synthesis, or gas-phase synthesis.

[0116] The forming method is preferably selected from at least one of the following: overflow method, floating method, downward drawing method, flow hole downward drawing method, re-dragging method, containerless method, blowing method, pressing method, roll forming method, stencil method, and tube drawing method. Alternatively, the glass can be reheated at a temperature above the glass transition temperature after forming. In this way, the glass of the present invention with excellent surface quality can be manufactured.

[0117] When forming is performed by overflow method, the viscosity of the glass at the lower top portion of the grooved refractory is preferably 10. 3.5 ~10 5.0 dPa·s. If the lower top portion of the grooved structure is not subjected to any force, the glass will shrink and fall downwards under the action of surface tension. To prevent this, the glass blank needs to be clamped on both sides with rollers and stretched in the width direction to prevent the glass blank from shrinking. When forming the glass of the present invention, since the glass itself has little heat, the cooling rate of the glass increases sharply the moment it leaves the grooved refractory. Therefore, at the lower top portion of the grooved refractory, the viscosity of the glass is preferably 10. 5.0 Below dPa·s, 10 4.8 Below dPa·s, 10 4.6 Below dPa·s, 10 4.4 Below dPa·s, 10 4.2 Below dPa·s, especially 10 4.0 Below dPa·s. In this way, when tensile stress is applied in the width direction, it is possible to prevent breakage and increase the width of the plate, while also enabling stable downward extension.

[0118] The obtained glass is then annealed. The purpose of annealing is primarily to remove strain and residual stress. In this case, it is preferable to perform heat treatment within a temperature range of room temperature to strain point (≈ glass transition temperature -5 to -20°C) for at least 1 minute, more preferably 3 minutes, 16 minutes, and most preferably more than 30 minutes. This makes it easy to obtain glass composed of only a single glass phase, resulting in improved chemical durability, easier control of the glass surface, and easier acquisition of the desired high transmittance. On the other hand, annealing can also eliminate strain and residual stress while simultaneously inducing phase separation within the glass. In this case, it is preferable to perform heat treatment within a temperature range above the strain point for at least 1 minute, more preferably 3 minutes, 16 minutes, and most preferably more than 30 minutes. This allows phase separation to occur in the glass, and the phase separation state is, in most cases, a bi-junctional decomposition. Furthermore, when phase separation occurs in the glass of the present invention, it separates into a first phase containing a large amount of SiO2 and a second and subsequent phases, but in most cases, the chemical durability of the phases after the second phase is lower than that of the first phase. In this case, due to differences in the chemical durability of each phase, the glass surface is prone to unevenness. However, by designing an appropriate glass composition as described above, the unevenness can be controlled to a level that achieves the desired transmittance. Furthermore, by imparting fine unevenness, not only is the release property of the glass of the present invention to objects in contact with it improved, but the surface area of ​​the glass is also made larger than that of a free surface. This increases friction and physical and chemical adsorption forces, thereby achieving high functionality of the glass of the present invention. Additionally, annealing can be performed while applying or irradiating sound waves or electromagnetic waves.

[0119] Furthermore, as described above, when the glass of the present invention requires a white or milky white appearance for applications such as cooktops, it is preferable to separate into two or more phases. To obtain glass with this white or milky white appearance, it is preferable to heat-treat the formed glass of the present invention by holding it in a temperature range above its strain point for at least one minute. Specifically, the heat-treating temperature is preferably 700°C or higher, 800°C or higher, 850°C or higher, particularly 900°C or higher, and preferably 1500°C or lower, 1200°C or lower, or 1100°C or lower. When the heat-treating temperature is too high, the glass changes from a solid state to a molten state, making it difficult to obtain the desired shape. On the other hand, when the heat-treating temperature is too low, phase separation is difficult to achieve efficiently, resulting in increased manufacturing costs. The heat-treating time is preferably 1 minute or more, 1 hour or more, 5 hours or more, 10 hours or more, 20 hours or more, particularly 24 hours or more, and preferably 1000 hours or less, 500 hours or less, 100 hours or less, or 50 hours or less. When the heat treatment time is outside the above range, it is difficult to obtain glass with the desired properties.

[0120] Furthermore, the cooling rate when cooling the glass of the present invention, which has reached a high temperature, can be set to a specific temperature gradient, or it can be set to a temperature gradient of two or more levels. When sufficient thermal shock resistance is desired, it is preferable to control the cooling rate to allow sufficient relaxation of the structure of the residual glass phase. In this case, the average cooling rate from the highest annealing temperature to 25°C is preferably 3000°C / min or less, 1000°C / min or less, 500°C / min or less, 400°C / min or less, 300°C / min or less, 200°C / min or less, 100°C / min or less, 50°C / min or less, 25°C / min or less, 10°C / min or less, and particularly 5°C / min or less, in the internal portion of the glass furthest from the surface of the glass of the present invention. Additionally, when long-term dimensional stability is desired, it is further preferred to be 2.5°C / min or less, 1°C / min or less, 0.5°C / min or less, 0.1°C / min or less, 0.05°C / min or less, and particularly 0.01°C / min or less. Except for cases where physical strengthening treatments such as air cooling and water cooling are used, the cooling rate of the glass is preferably close to the cooling rate of the interior wall thickness furthest from the glass surface. The value obtained by dividing the cooling rate of the interior portion of the glass furthest from the surface by the surface cooling rate is preferably 0.0001–1, 0.001–1, 0.01–1, 0.1–1, 0.5–1, 0.8–1, 0.9–1, and especially 1. By being close to 1, residual strain is less likely to occur at all locations in the glass of the present invention, and long-term dimensional stability is easily obtained. Furthermore, the surface cooling rate can be estimated using a contact thermometer or a radiation thermometer. The temperature inside the glass can be estimated based on numerical data obtained by immersing the high-temperature glass in a cooling medium and measuring the heat and rate of change of the cooling medium, as well as the specific heat and thermal conductivity of the glass and the cooling medium.

[0121] The resulting glass of the present invention can be cut. For example, when cutting using a wire saw, it is preferable to cut while supplying a slurry containing abrasive particles to the wire saw.

[0122] It may also include a process of crystallizing glass obtained by heat treatment through a process of forming molten glass.

[0123] Specifically, crystallized glass can be obtained by heat-treating annealed glass to induce crystallization. The crystallization conditions are as follows: First, nucleation is performed at 700°C to 1200°C (preferably 750°C to 900°C) for 0.1 to 60 hours (preferably 0.25 to 50 hours, more preferably 1 to 40 hours), followed by crystal growth at 800 to 1300°C (preferably 850 to 1100°C) for 0.1 to 50 hours (preferably 0.2 to 10 hours, more preferably 0.25 to 5 hours). The heat treatment in each step of nucleation and crystal growth can be performed at a specific temperature, or in stages at two or more temperature levels, or under a temperature gradient. Alternatively, heat treatment for crystal growth can be performed without nucleation. In this way, crystallized glass with, for example, the following crystals precipitated can be obtained. Specifically, these include Al₂SiO₅ (aluminum silicate), zirconium oxide, zirconium titanate, tin-containing zirconium oxides, titanium oxide, aluminum titanate, β-quartz solid solution, α-quartz, β-quartz, β-spodumene solid solution, spodumene, zircon, cordierite, enstatite, mica, nepheline, anorthite, lithium disilicate, lithium metasilicate, wollastonite, diopside, cristobalite, tridymite, feldspar crystals, and metallic colloids. Furthermore, these crystals may contain only one type or more.

[0124] Alternatively, crystallization can be induced by annealing, or promoted by applying or irradiating sound waves or electromagnetic waves. Furthermore, the cooling rate during the cooling of the crystallized glass of the present invention, which has reached a high temperature, can be set to a specific temperature gradient, or to a temperature gradient of two or more levels. Preferably, the cooling rate is the same as that of the glass described above.

[0125] Example The present invention is described below based on embodiments, but the present invention is not limited to the following embodiments. Tables 1 to 32 show the composition and characteristic values ​​of the glass (samples No. 1 to 80) in the embodiments of the present invention.

[0126] [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] [Table 7] [Table 8] [Table 9] [Table 10] [Table 11] [Table 12] [Table 13] [Table 14] [Table 15] [Table 16] [Table 17] [Table 18] [Table 19] [Table 20] [Table 21] [Table 22] [Table 23] [Table 24] [Table 25] [Table 26] [Table 27] [Table 28] [Table 29] [Table 30] [Table 31] [Table 32] First, the raw materials are mixed in the forms of oxides, hydroxides, carbonates, nitrates, etc., to obtain glass batches with the compositions listed in the tables (the compositions listed in Table 1 are the analytical values ​​of the actual manufactured glass, and the analysis was performed using a RIGAKU ZSX series scanning fluorescence X-ray analyzer). The obtained glass batches are melted at 1200–1800°C for 0.5–400 hours, and then rolled using a roll forming method while cooling the molten glass to form a shape with a width of 100 mm and a thickness of 5 mm. Then, the glass is heat-treated in a slow-cooling furnace at a temperature of -150 to -50°C (glass transition temperature) for 30 minutes, and the slow-cooling furnace is cooled to room temperature at a rate of -100°C / h, thereby obtaining glasses No. 1 to 80.

[0127] Glass samples were processed using physical grinding, chemical grinding, chemical etching, and fire blasting to create evaluation samples for β-OH value, viscosity, liquidus temperature, liquidus viscosity, density, linear thermal expansion coefficient, Young's modulus, rigidity modulus, and Poisson's ratio. Additionally, the molten glass was formed into 400mm lengths using an overflow method and heat-treated in a slow-cooling furnace at a temperature of -150 to -50°C (glass transition temperature) for 30 minutes. The furnace was then cooled to room temperature at a rate of -100°C / h to obtain glass plates. The surface roughness Ra of the main surface, the surface roughness Ra of the end surfaces, and the waviness of the obtained glass plates were measured.

[0128] The Pt and Rh contents of the prepared samples were analyzed using an ICP-MS apparatus (Agilent 8800, manufactured by AGILEINT TECHNOLOGY) as follows: First, the prepared glass samples were pulverized and moistened with pure water, then dissolved by adding perchloric acid, nitric acid, sulfuric acid, hydrofluoric acid, etc. The Pt and Rh contents of the samples were then determined using ICP-MS (Inductively Coupled Plasma Mass Spectrometry). Additionally, the Pt and Rh contents of each sample were determined based on calibration curves prepared using pre-prepared Pt and Rh solutions of known concentrations. The measurement modes were set to Pt:He gas / HMI (low mode) and Rh:HEHe gas / HMI (medium mode), with mass numbers set to Pt: 198 and Rh: 103. Furthermore, the Li₂O content of the prepared samples was analyzed using an atomic absorption spectrometry apparatus (Analytik Jena ContrAA 600). The melting procedure for the glass samples and the use of calibration curves were essentially the same as for the Pt and Rh analysis. In addition, other components are determined using ICP-MS or atomic absorption spectrometry, similar to Pt, Rh, and Li₂O. Alternatively, a glass sample with a known concentration, pre-analyzed using ICP-MS or atomic absorption spectrometry, can be used as a calibration curve. A calibration curve is then created using an XRF (X-ray fluorescence) analyzer (RIGAKU ZSX Primus IV). Based on this calibration curve, the actual content of each component is determined from the XRF analysis values ​​of the measured sample. During XRF analysis, the tube voltage or current, exposure time, etc., are adjusted continuously according to the components being analyzed.

[0129] Density was evaluated using the Archimedes method.

[0130] The transmittance of the glass was determined using an infrared spectrophotometer (FT-IR Frontier, PerkinElmer) and calculated using the following formula. The scanning speed was set to 100 μm / min and the sampling interval to 1 cm. －1 The number of scans is set to 10 scans per measurement.

[0131] β-OH value = (1 / X)log(T1 / T2) X: Glass wall thickness T1: Reference wave number 3846cm －1 Transmittance at time T2: OH group absorption wavenumber 3600cm －1 Near minimum transmittance The linear coefficient of thermal expansion was evaluated using the average linear coefficient of thermal expansion measured in the temperature ranges of 30–380 °C and 30–750 °C using specimens machined to a diameter of 20 mm × 3.8 mm φ. Measurements were performed using a NETZSCH dilatometer. Additionally, using the same measuring instrument, the thermal expansion curves of the glass specimens were measured in the temperature range of 30–750 °C, and the inflection points were calculated to evaluate the glass transition temperature and yield point.

[0132] High-temperature viscosity was evaluated using the platinum ball pulling method, as described below. A block of glass was broken into appropriate sizes and placed in an alumina crucible. The alumina crucible was then heated until the sample was in a molten state. Viscosities of the glass were measured at multiple temperatures, the Vogel-Fulcher constant was calculated, viscosity curves were plotted, and the viscosity values ​​at various temperatures (10⁻⁶) were calculated. 4 dPa·s, 10 3.5 dPa·s, 10 3 dPa·s, 10 2.5 dPa·s and 10 2 Temperature at dPa·s.

[0133] The liquidus temperature was evaluated as follows: First, glass powder of uniform size (300–500 μm) was filled into a platinum boat of approximately 120 × 20 × 10 mm and placed in an electric furnace, where it was melted at 1400–1800 °C for 30 minutes. Then, the platinum boat was transferred to an electric furnace with a linear temperature gradient and held for 20 hours to allow devitrification. After the sample was cooled to room temperature, devitrification was observed at the interface between the platinum boat and the glass. The temperature at which the devitrification occurred was calculated based on the temperature gradient curve of the electric furnace and taken as the liquidus temperature. Furthermore, the obtained liquidus temperature was interpolated to the high-temperature viscosity curve of the glass, and the viscosity corresponding to the liquidus temperature was evaluated as the liquidus viscosity.

[0134] Transmittance, lightness, and chromaticity were evaluated using a spectrophotometer with a 4 mm thick sample having a surface roughness comparable to optical polishing. Measurements were performed using a Japanese spectrophotometer, the V-670. The V-670 is equipped with an integrating sphere unit, "ISN-723," and the measured transmittance corresponds to the total light transmittance. The measurement wavelength range was set to 200–2500 nm, the scan rate to 200 nm / min, the sampling interval to 1 nm, and the bandwidth to 5 nm in the 200–800 nm wavelength range and 20 nm in other wavelength ranges. Baseline correction (100% matching) and dark area measurements (0% matching) were performed before measurement. Dark area measurements were performed with the barium sulfate plate provided with the ISN-723 removed. Using the measured transmittance, the tristimulus values ​​XYZ are calculated based on JIS Z8781-42013 and its corresponding international standard. The lightness and chromaticity (light source C / 10°) are then calculated based on each stimulus value.

[0135] The surface roughness Ra of the main surface and end face of the glass was determined according to the method of JIS B0601:2001.

[0136] The waviness was measured using a stylus-type surface shape measuring device, specifically the WCA (Waviness of Filter Centerline) value as described in JIS B0601:2001. This measurement was performed according to SEMI STD D15-1296, "Method for Determination of Surface Waviness of FPD Glass Substrates." The cutoff value for the measurement was set to 0.8–8 mm, and the measurement was conducted over a length of 300 mm in a direction perpendicular to the rolling direction of the glass during molding.

[0137] Color and appearance are determined by visual inspection.

[0138] The glasses in Embodiments No. 1 to 80 of the present invention are materials with low linear thermal expansion coefficients and high heat resistance and thermal shock resistance. Nos. 1 to 22, 24 to 48, 51 to 52, and 77 to 80 are colorless and transparent, while Nos. 23, 49 to 50, and 53 to 76 are colored black or slightly brown.

[0139] Industrial availability The glass of the present invention is preferably used for cooktops, fireproof windows, heat-resistant tableware, or building components. Specifically, the glass of the present invention is suitable for use as: front windows for kerosene stoves, wood-burning stoves, etc.; substrates for high-tech products such as color filters or image sensor substrates; fixing devices for electronic component fabrication; diffuser plates; core tubes for semiconductor manufacturing; masks for semiconductor manufacturing; optical lenses; dimensional measuring components; communication components; building components; containers for chemical reactions; cooktops for electromagnetic cooking; heat-resistant tableware; heat-resistant covers; window glass for fireproof doors; components for astronomical telescopes; components for cosmological optics; coloring materials; light-absorbing materials; temperature-regulating materials; sound-insulating materials; dielectric components; linear thermal expansion coefficient regulating materials; battery components; components for strengthening resins, etc.; display components; chemically strengthening materials, etc. Furthermore, when the glass of the present invention is crystallized glass, it is preferably used for cooktops, fireproof windows, heat-resistant tableware, or building components. However, the uses of the glass of the present invention with a low linear thermal expansion coefficient are not limited to the above uses. It can also be used for the individual uses described above, or for uses combining the above uses. Examples of such combinations include electromagnetic cooking cooktops with display functions, or smartphones with displays that have undergone chemical fortification.

Claims

1. A type of glass, characterized in that, It contains 45-80% SiO2, 10-30% Al2O3, 0-12% B2O3, and 0-5% Li2O by mass percentage.

2. The glass as described in claim 1, characterized in that, It contains more than 0% P2O5 by mass percentage.

3. The glass as described in claim 1 or 2, characterized in that, It contains more than 0% TiO2 by mass percentage.

4. The glass as described in claim 3, characterized in that, It contains more than 0% and less than 8% B2O3, 0-3% Li2O, and 6.5-20% P2O5 by mass percentage.

5. The glass as described in claim 1 or 2, characterized in that, It contains more than 0% Fe2O3 by mass percentage.

6. The glass as described in claim 1 or 2, characterized in that, It contains less than 10% HfO2 by mass percentage.

7. The glass as described in claim 1 or 2, characterized in that, It contains less than 0.05% Pt and less than 0.05% Rh by mass percentage.

8. The glass as described in claim 1 or 2, characterized in that, It contains more than 0% SnO2 by mass percentage.

9. The glass as described in claim 1 or 2, characterized in that, It contains less than 12.5% ​​ZnO by mass percentage.

10. The glass as claimed in claim 1 or 2, characterized in that, It contains less than 15% Li2O + Na2O + K2O by mass percentage.

11. The glass as claimed in claim 1 or 2, characterized in that, It contains more than 0% ZrO2 by mass percentage.

12. The glass as claimed in claim 1 or 2, characterized in that, The percentage by mass is greater than 0.01 (P2O5×TiO2) / (Al2O3+P2O5).

13. The glass as claimed in claim 1 or 2, characterized in that, The mass percentage of P2O5×TiO2 is above 0.

22.

14. The glass as claimed in claim 1 or 2, characterized in that, By mass percentage, MgO+CaO+SrO+BaO is less than 5.9%, Li2O+Na2O+K2O is less than 2.6%, and P2O5×TiO2 is more than 0.01%.

15. The glass as claimed in claim 1 or 2, characterized in that, The linear thermal expansion coefficient at 30–750℃ is 60 × 10⁻⁶. －7 / ℃ below.

16. The glass as claimed in claim 1 or 2, characterized in that, The transmittance is above 0.1% at a thickness of 4mm and a wavelength of 555nm.

17. The glass as claimed in claim 1 or 2, characterized in that, It is used in cookware tops, fireproof windows, heat-resistant tableware, or building components.

18. A type of glass, characterized in that, By mass percentage, it contains 45–80% SiO2, 10–30% Al2O3, 0–12% B2O3, more than 0% and less than 20% P2O5, 0–5% MgO + CaO + SrO + BaO, and 0–5% Li2O + Na2O + K2O. The ratio of (P2O5×TiO2) / (Al2O3+P2O5) is greater than 1.

4. The linear thermal expansion coefficient at temperatures ranging from 30 to 750℃ is 40 × 10⁻⁶. －7 / ℃ below.

19. A type of glass, characterized in that, By mass percentage, it contains 45–80% SiO2, 10–30% Al2O3, 0–12% B2O3, more than 0% and less than 20% P2O5, less than 5% Li2O, more than 0% and less than 20% ZrO2, 0–8% MgO + CaO + SrO + BaO, and 0–2.9% Li2O + Na2O + K2O. (MgO + CaO + SrO + BaO) / P₂O₅ is below 3.

8. The linear thermal expansion coefficient at temperatures ranging from 30 to 750℃ is 40 × 10⁻⁶. －7 / ℃ below.

20. The glass as claimed in claim 18 or 19, characterized in that, It contains more than 0% TiO2 by mass percentage.

21. A top plate for a cooking appliance, characterized in that, The linear thermal expansion coefficients at 30–380℃ and 30–750℃ are 5–40 × 10⁻⁶. －7 / ℃, The transmittance is above 0.1% at a thickness of 4mm and a wavelength of 555nm.

22. A method for manufacturing glass, for producing the glass according to claim 1 or 2, characterized in that, It includes the process of melting glass raw materials to obtain molten glass, and the process of shaping the molten glass. The method for forming the molten glass is selected from at least one of the following: overflow method, floating method, downward drawing method, flow hole downward drawing method, re-dragging method, containerless method, blowing method, pressing method, roll pressing method, stencil method and tube drawing method.

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