Glass and method for producing same

Abstract

Provided is a glass having a low linear thermal expansion coefficient and excellent light transmissivity as an alternative to Li2O-Al2O3-SiO2-based crystallized glass. The glass is characterized by containing, in mass%, 45-80% of SiO2, 10-30% of Al2O3, 0-12% of B2O3, and 0-5% of Li2O.

Description

[Rule 26 Supplement 14.06.2024] Glass and its manufacturing method

[0001] The present invention relates to glasses having low linear thermal expansion properties.

[0002] Conventionally, crystallized glass has been used as a material for front windows of oil stoves, wood stoves, etc., setters for firing electronic components, furnace tubes for semiconductor manufacturing, members for dimension measurement, members for communication, building members, containers for chemical reactions, top plates for electromagnetic cooking, heat-resistant tableware, heat-resistant covers, window glass for fire doors, members for astronomical telescopes, and linear thermal expansion coefficient adjusting materials. For example, Patent Documents 1 to 3 disclose crystallized glass containing β-quartz solid solution (Li ２ O.Al ２ O ３ nSiO ２ [where 2≦n≦4]) and β-spodumene solid solution (Li ２ O.Al ２ O ３ nSiO ２ [where n≧4]) ２ O-Al ２ O ３ -SiO ２ Glass-ceramics obtained by precipitating system crystals are disclosed.

[0003] Generally, crystallized glass has a low coefficient of linear thermal expansion and high mechanical strength, and therefore has excellent thermal properties. In addition, by appropriately adjusting the heat treatment conditions in the crystallization process, it is possible to control the type of precipitated crystals, and crystallized glass with high translucency can be easily produced.

[0004] Japanese Patent Publication No. 39-21049 Publication No. 40-20182 Japanese Patent Publication No. 1-308845

[0005] In recent years, the lithium-ion battery market has expanded due to the increasing demand for electronic devices such as electric vehicles, smartphones, and tablets. As a result, there is a shortage of lithium raw materials in various industries, and the price of lithium raw materials has risen worldwide. ２ O-Al ２ O ３ -SiO ２ It has become difficult to stably produce and supply glass-ceramics based on this system to the market.

[0006] Against this background, Li ２ O-Al ２ O ３ -SiO ２ There is a demand for materials with low linear thermal expansion coefficients and excellent light transmittance to replace glass-ceramics.

[0007] The object of the present invention is to ２ O-Al ２ O ３ -SiO ２ The present invention aims to provide a glass having a low coefficient of linear thermal expansion and excellent light transmittance, which can be used as an alternative to glass-ceramics.

[0008] As a result of extensive research, the present inventors have found that by appropriately designing the glass composition, it is possible to obtain glass that has a low linear thermal expansion coefficient and excellent light transmittance. Here, "light transmittance" means that the transmittance (total light transmittance) at any wavelength of 1200 nm, 800 nm, 555 nm, 380 nm, or 300 nm at a thickness of 4 mm is greater than 0%.

[0009] The glass of the present invention contains, in mass %, SiO ２ 45-80%, Al ２ O ３ 10-30%, B ２ O ３ 0-12%, Li ２ O 0 to 5%.

[0010] The glass of the present invention contains, in mass %, P ２ O ５ It is preferable that the content is more than 0%.

[0011] The glass of the present invention contains, in mass %, TiO ２ It is preferable that the content is more than 0%.

[0012] The glass of the present invention contains, in mass %, B ２ O ３ Over 0 to 8%, Li ２ O 0-3%, P ２ O ５ It is preferable that the content is 6.5 to 20%.

[0013] The glass of the present invention contains, in mass %, Fe ２ O３ It is preferable that the content is more than 0%.

[0014] The glass of the present invention contains, in mass %, HfO ２ It is preferable that the content is 10% or less.

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

[0016] The glass of the present invention contains, in mass %, SnO ２ It is preferable that the content is more than 0%.

[0017] The glass of the present invention preferably contains, by mass %, 12.5% ​​or less of ZnO.

[0018] The glass of the present invention contains, in mass %, Li ２ O + Na ２ O+K ２ It is preferable that the content of O is 15% or less.

[0019] The glass of the present invention contains, in mass %, ZrO ２ It is preferable that the content is more than 0%.

[0020] The glass of the present invention contains, in mass %, (P ２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５ ) is preferably 0.01 or more.

[0021] The glass of the present invention contains, in mass %, P ２ O ５ ×TiO ２ is preferably 0.22 or more.

[0022] The glass of the present invention contains, in mass %, MgO + CaO + SrO + BaO in an amount of 5.9% or less, Li ２ O + Na ２ O+K ２ O 2.6% or less, P ２ O ５ ×TiO ２ It is preferably 0.01 or more.

[0023] The glass of the present invention has a linear thermal expansion coefficient of 60×10 at 30 to 750° C. －７ / °C or less is preferred.

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

[0025] The glass of the present invention is preferably used for a top plate for a cooker, a fire window, heat-resistant tableware or a building component.

[0026] The glass of the present invention contains, in mass %, SiO ２ 45-80%, Al ２ O ３ 10-30%, B ２ O ３ 0-12%, P ２ O ５ More than 0 to 20%, MgO + CaO + SrO + BaO 0 to 5%, Li ２ O + Na ２ O+K ２ O 0 to 5%, (P ２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５ ) is 1.4 or more, and the linear thermal expansion coefficient at 30 to 750 ° C is 40 × 10 －７ / °C or less.

[0027] The glass of the present invention contains, in mass %, SiO ２ 45-80%, Al ２ O ３ 10-30%, B ２ O ３ 0-12%, P ２ O ５ Over 0 to 20%, Li ２ O 5% or less, ZrO ２ More than 0 to 20%, MgO + CaO + SrO + BaO 0 to 8%, Li ２ O + Na ２ O+K ２ O 0-2.9%, (MgO+CaO+SrO+BaO) / P ２ O ５3.8 or less, and the linear thermal expansion coefficient at 30 to 750°C is 40 x 10 －７ / °C or less.

[0028] The glass of the present invention has a linear thermal expansion coefficient of 5 to 40×10 at temperatures from 30 to 380° C. and from 30 to 750° C. －７ / °C, a thickness of 4 mm, and a transmittance of 0.1% or more at a wavelength of 555 nm.

[0029] The method for producing glass of the present invention is a method for producing any of the above glasses, comprising a step of melting glass raw materials to obtain molten glass, and a step of shaping the molten glass, wherein the method for shaping the molten glass is at least one method selected from the group consisting of an overflow method, a float method, a downdraw method, a slot-down method, a redraw method, a containerless method, a blowing method, a pressing method, a rolling method, a bushing method, and a tube drawing method.

[0030] According to the present invention, Li ２ O-Al ２ O ３ -SiO ２ It is possible to provide a glass having excellent light transmittance and thermal properties, which can be used as an alternative to glass-ceramics.

[0031] The glass of the present invention (hereinafter also simply referred to as "glass") contains, in mass %, SiO ２ 45-80%, Al ２ O ３ 10-30%, B ２ O ３ 0-12%, Li ２ The reason for restricting the content and properties of each component as described above will be explained below. In the following explanation of the content of each component, "%" means "% by mass" unless otherwise specified.

[0032] SiO ２ is a component that forms the glass skeleton. It is also a component that may be particularly involved in the ease with which phase separation occurs. ２The content of SiO is 45 to 80%, with the lower limit being preferably 46% or more, 47% or more, 48% or more, and particularly preferably 49% or more, and the upper limit being preferably 79% or less, 78% or less, 77% or less, and particularly preferably 76% or less. ２ If the content of SiO is too low, the coefficient of linear thermal expansion tends to be high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Also, chemical durability tends to be reduced. ２ If the content is too high, the homogeneity of the glass melt is likely to decrease. ２ Scum with a high content of cristobalite is likely to be generated, and devitrification such as cristobalite will precipitate from the scum, which will likely increase the production load. Here, scum refers to unreacted matter and floating matter on the surface of the molten glass in the melting furnace, and refers to a substance whose main component is cristobalite.

[0033] Al ２ O ３ Al is a component that forms the glass skeleton. It is also a component that may be involved in the ease of phase separation. ２ O ３ The content of Al is 10 to 30%, with the lower limit being preferably 11% or more, 12% or more, 13% or more, 14% or more, and particularly preferably 15% or more, and the upper limit being preferably 29% or less, 28% or less, 27% or less, and particularly preferably 26% or less. ２ O ３ If the content of Al is too low, the linear thermal expansion coefficient tends to be high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. In addition, chemical durability decreases, and the glass surface is prone to deterioration. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired transmittance. On the other hand, ２ O ３ If the content is too high, the homogeneity of the glass melt is likely to decrease, and further, crystals such as mullite tend to precipitate, causing the glass to devitrify, making the glass more susceptible to breakage.

[0034] B ２ O ３is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that may be particularly involved in the ease with which phase separation occurs. Furthermore, it has the effect of reducing the linear thermal expansion coefficient and improving heat resistance and thermal shock resistance. ２ O ３ The content of is 0 to 12%, and the lower limit is preferably more than 0%, 0.5% or more, 1% or more, and particularly preferably 1.5% or more, 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, and particularly preferably 5% or less. ２ O ３ If the content is too high, the B ２ O ３ The amount of evaporation of B increases, and B appears on the surface of the glass melt. ２ O ３ The content of SiO is relatively low ２ As a result, devitrification such as cristobalite is likely to occur from the scum, increasing the production load. In addition, the chemical durability of the glass is reduced, and the glass surface is more likely to be altered, which deteriorates the surface irregularities and makes it difficult to obtain glass with the desired high transmittance. ２ O ３ is easily mixed in as an impurity, ２ O ３ If we try to completely eliminate B, the raw material batch will become expensive and the manufacturing cost will tend to increase. ２ O ３ The content may be 0.0001% or more, 0.0003% or more, particularly 0.0005% or more.

[0035] Li ２ O is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that can be involved in the phase separation of glass. ２The O content is 0 to 5%, and the upper limit is preferably 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2% or less, 1.9% or less, 1.8% or less, 1.5% 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, and particularly preferably 0.3% or less. ２ If the O content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass is reduced, and the glass surface is likely to be altered. As a result, the surface irregularity condition deteriorates, making it difficult to obtain glass with a desired high transmittance. In addition, Li ２ O is easily mixed in as an impurity, so Li ２ If an attempt is made to completely remove O, the raw material batch becomes expensive and the manufacturing cost tends to increase. Therefore, in order to suppress the increase in manufacturing cost, ２ The lower limit of the O content is preferably more than 0%, 0.0001% or more, 0.0002% or more, 0.0003% or more, 0.0004% or more, 0.0005% or more, particularly preferably 0.001% or more.

[0036] The glass of the present invention may contain the following components in addition to the above components.

[0037] P ２ O ５ In the glass of the present invention, P is a component that reduces the linear thermal expansion coefficient of the glass. It is also a component that adjusts the refractive index. It is also a component that can be involved in phase separation of the glass. ２ O ５ The content of is preferably 0 to 30%. The lower limit is preferably more than 0%, 0.1% or more, 1% or more, 2% or more, 3% or more, 4% or more, 4.5% or more, and particularly preferably 6.5% or more, and the upper limit is preferably 25% or less, 20% or less, 18% or less, 17% or less, and particularly preferably 16% or less. ２ O ５If the content is too high, the viscosity of the glass becomes too high, which tends to reduce the homogeneity of the glass melt. Furthermore, the chemical durability of the glass decreases, and the glass surface tends to be altered. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired transmittance. Furthermore, the devitrification resistance tends to decrease.

[0038] P ２ O ５ is a component that reduces the linear thermal expansion coefficient of the glass in the present invention, while P ２ O ５ If the content of B is too high, the viscosity of the glass increases, and the melting property of the glass tends to decrease. ２ O ３ is a component that can reduce the viscosity of the glass. If the viscosity of the glass is too high, for example, higher temperatures are required when melting or molding the glass, which tends to put a strain on the manufacturing equipment and increase energy costs, and thus productivity is likely to decrease. Therefore, in order to reduce the viscosity of the glass while reducing the linear thermal expansion coefficient and obtain a glass with good productivity, B ２ O ３ / P ２ O ５ (B ２ O ３ and P ２ O ５ It is preferable to strictly control the content of B. ２ O ３ / P ２ O ５ is preferably 0 or more, 0.01 or more, 0.1 or more, 0.2 or more, particularly preferably 0.3 or more, and is preferably 550 or less, 300 or less, 100 or less, 50 or less, 10 or less, particularly preferably 1 or less.

[0039] TiO ２ is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It also lowers the linear thermal expansion coefficient. It also absorbs light of various wavelengths and is a coloring component of glass. In particular, when titanium and iron coexist, it produces ilmenite (FeTiO ３It is known that when titanium and tin coexist, the yellow color becomes stronger. ２ is also a component that may be particularly involved in the ease with which phase separation occurs. ２ The content of TiO is preferably 0% or more, more 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 preferably 6% or more, and is preferably 20% or less, 18% or less, 16% or less, 14% or less, particularly preferably 12% or less. ２ When the content of TiO exceeds 0%, the linear thermal expansion coefficient tends to be low. ２ If the content of TiO is too high, the meltability of the glass is likely to decrease. In addition, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. Therefore, for example, in order to obtain glass with a colorless and highly transparent appearance, TiO ２ The content may be 3% or less, 2% or less, or 1% or less.

[0040] In the glass of the present invention, P ２ O ５ is a component that can reduce the linear thermal expansion coefficient of glass, and this effect is enhanced by TiO ２ However, in the viscosity of glass, P ２ O ５ contributes to the increase, and TiO ２ Therefore, in order to reduce the linear thermal expansion coefficient while appropriately suppressing an increase in the viscosity of the glass and obtain a glass with good productivity, it is necessary to add P. ２ O ５ ×TiO ２ (P ２ O ５ and TiO ２ It is preferable to strictly control the content of P ２ O ５ ×TiO ２is preferably 0 or more, more 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, and particularly preferably 15 or more, and is preferably 900 or less, 500 or less, 300 or less, 150 or less, 100 or less, 80 or less, and particularly preferably 60 or less. ２ O ５ ×TiO ２ If P is too large, the viscosity of the glass tends to be high, which reduces productivity. ２ O ５ ×TiO ２ is preferably greater than 0%.

[0041] P ２ O ５ and TiO ２ are components that reduce the coefficient of linear thermal expansion, and P ２ O ５ contributes to an increase in the viscosity of the glass, and TiO ２ contributes to a decrease in the viscosity of the glass. ２ O ３ is a component that forms the glass skeleton and can contribute to reducing the linear expansion coefficient of the glass. ２ O ５ and TiO ２ If the content of (P) is too large, the viscosity of the glass will decrease and the liquidus temperature will increase, which will result in a decrease in productivity. ２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５ ) (P ２ O ５ and TiO ２ and the product of the content of Al ２ O ３ and P ２ O ５and the ratio to the sum of the contents of (a) and (b) is preferably 0 or more, more than 0, 0.000001 or more, 0.000002 or more, 0.0000016 or more, 0.00001 or more, 0.0001 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, particularly 1.9 or more, and is preferably 10 or less, 5 or less, particularly 4 or less.

[0042] Fe ２ O ３ is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It is also a component that releases oxygen-based gases through oxidation-reduction reactions and can also contribute to the clarification of glass. It is also a component that absorbs light of various wavelengths, coloring glass, and can also contribute to phase separation of glass. ２ O ３ The content of is preferably 0% or more, more than 0%, 0.0001% or more, 0.001% or more and 0.005% or more, particularly preferably 0.01% or more. ２ O ３ If the content of Fe is too high, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. In addition, devitrification containing Fe is likely to occur, increasing the production load. ２ O ３ The content of Fe is preferably 20% or less, 15% or less, 10% or less, 5% or less, 1% or less, 0.5% or less, and particularly preferably 0.1% or less. ２ O ３ For example, when a colored (e.g., black) appearance is required for a cooking top plate or the like, the content of Fe may be controlled to adjust the transmittance. ２ O ３ The content may be 0.05% or more, 0.08% or more, 0.1% or more, 0.2% or more, particularly 0.3% or more.

[0043] Na ２ O is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of glass, and is also a component that can be involved in the phase separation of glass. ２The O content is preferably 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 preferably 0.05% or less. ２ If the O content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass decreases, and the glass surface is likely to be altered. As a result, the surface irregularity deteriorates, making it difficult to obtain glass with a desired high transmittance. In addition, Na ２ O is easily mixed in as an impurity, so Na ２ If an attempt is made to completely remove O, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ The lower limit of the O content is preferably more than 0%, 0.0001% or more, 0.0003% or more, 0.0005% or more, 0.001% or more, 0.002% or more, 0.004% or more, 0.006% or more, 0.008% or more, particularly preferably 0.01% or more.

[0044] K ２ O is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of glass, and is also a component that can be involved in the phase separation of glass. ２ The O content is preferably 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 preferably 0.05% or less. ２ If the O content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass decreases, and the glass surface is likely to be altered. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with a desired high transmittance. ２ O is easily mixed in as an impurity, so K ２If an attempt is made to completely remove O, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ The lower limit of the O content is preferably more than 0%, 0.0001% or more, 0.0003% or more, 0.0005% or more, and particularly preferably 0.001% or more.

[0045] Li ２ O, Na ２ O.K. ２ O is a component that reduces the viscosity of the glass and improves the meltability and formability of the glass. It is also a component that can be involved in the phase separation of the glass. ２ O + Na ２ O+K ２ O(Li ２ O, Na ２ O.K. ２ The total content of Li and O is preferably 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, 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, 2.1% or less, 2% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% 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, 0.1% or less, and particularly preferably 0.05% or less. ２ O + Na ２ O+K ２ If there is too much O, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass is reduced, and the glass surface is likely to be altered. As a result, the surface irregularity condition deteriorates, making it difficult to obtain glass with a desired high transmittance. In addition, Li ２ O, Na ２ O.K. ２ Since O is easily mixed in as an impurity, if it is attempted to completely remove it, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ O + Na２ O+K ２ The lower limit of the O content is preferably more than 0%, 0.0001% or more, 0.001% or more, and particularly preferably 0.01% or more.

[0046] MgO is a component that reduces the viscosity of glass and improves its meltability and formability. It also reduces the linear thermal expansion coefficient of glass and adjusts its refractive index. It is also a component that can contribute to phase separation in glass. The MgO content is preferably 0% or more, 1% or more, 2% or more, 3% or more, and particularly 4% or more, and is preferably 40% or less, 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, and particularly 6% or less. If the MgO content is too high, the linear thermal expansion coefficient becomes too 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 more likely to deteriorate. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. Since MgO is easily mixed in as an impurity, attempting to completely remove MgO tends to increase the cost of the raw material batch and manufacturing costs. In order to suppress an increase in production costs, the lower limit of the MgO content is preferably 0.0001% or more, 0.001% or more, and particularly preferably 0.01% or more.

[0047] CaO is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of glass. It is also a component that can contribute to phase separation of glass. The CaO content is preferably 0% or more, 1% or more, 2% or more, 3% or more, and particularly 4% or more, and is preferably 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, and particularly 6% or less. If the CaO content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass is reduced, and the glass surface is likely to be altered. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired high transmittance. Note that CaO is easily mixed in as an impurity, and attempting to completely remove CaO tends to increase the cost of the raw material batch and the manufacturing cost. In order to suppress an increase in production costs, the lower limit of the CaO content is preferably 0.0001% or more, 0.001% or more, and particularly preferably 0.01% or more.

[0048] SrO is a component that reduces the viscosity of glass and improves its meltability and formability. It also adjusts the linear thermal expansion coefficient and refractive index of glass. It is also a component that can contribute to phase separation in glass. The SrO content is preferably 0% or more, 1% or more, 2% or more, 3% or more, and particularly 4% or more, and is preferably 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, and particularly 6% or less. If the SrO content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. Furthermore, the chemical durability of the glass is reduced, and the glass surface is likely to be altered. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired high transmittance. Since SrO is easily mixed in as an impurity, attempting to completely remove SrO tends to increase the cost of the raw material batch and the manufacturing cost. In order to suppress an increase in production costs, the lower limit of the SrO content is preferably 0.0001% or more, 0.001% or more, and particularly preferably 0.01% or more.

[0049] BaO is a component that reduces the viscosity of glass and improves its meltability and formability. It also adjusts the linear thermal expansion coefficient and refractive index of glass. It is also a component that can contribute to phase separation in glass. The BaO content is preferably 0% or more, 1% or more, 2% or more, 3% or more, and particularly 4% or more, and is preferably 30% or less, 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, and particularly 6% or less. If the BaO content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the meltability of glass tends to decrease. Furthermore, the chemical durability of the glass decreases, and the glass surface is easily altered. As a result, the surface roughness deteriorates, making it difficult to obtain glass with the desired high transmittance. Since BaO is easily mixed in as an impurity, attempting to completely remove BaO tends to increase the cost of the raw material batch and manufacturing costs. In order to suppress an increase in production costs, the lower limit of the BaO content is preferably 0.0001% or more, 0.001% or more, and particularly preferably 0.01% or more.

[0050] MgO, CaO, SrO, and BaO are components that reduce the viscosity of glass and improve the meltability and formability of the glass. On the other hand, MgO, CaO, SrO, and BaO are also components that increase the linear expansion coefficient of glass, and if their contents are too high, it becomes difficult to obtain glass with excellent heat resistance and thermal shock resistance. In addition, the chemical durability of the glass tends to decrease, and the glass surface tends to be easily altered, resulting in a worsened surface unevenness and making it difficult to obtain glass with the desired high transmittance. Therefore, the total content of MgO+CaO+SrO+BaO (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 particularly preferably 0.1% or less. Furthermore, in order to improve the meltability and formability of the glass, the total content is preferably 0.1% or more, 1% or more, 2% or more, 3% or more, and particularly preferably 4% or more. Since MgO, CaO, SrO, and BaO are easily mixed in as impurities, attempting to completely remove them tends to increase the cost of the raw material batch and the manufacturing cost. In order to suppress the increase in manufacturing cost, the lower limit of the content of MgO + CaO + SrO + BaO is preferably more than 0%, 0.0001% or more, 0.0003% or more, 0.0005% or more, particularly 0.001% or more.

[0051] MgO, CaO, SrO, and BaO are components that reduce the viscosity of the glass and improve the meltability and formability of the glass. ２ O ５ is a component that greatly contributes to the low expansion of glass, and is also a component that increases the viscosity of glass and improves phase separation. (MgO+CaO+SrO+BaO) / P ２ O ５ (The total content of MgO, CaO, SrO, and BaO is P ２ O ５(MgO+CaO+SrO+BaO) / P is preferably 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 preferably 3.8% or less. ２ O ５ If (MgO+CaO+SrO+BaO) / P is too large, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. On the other hand, if (MgO+CaO+SrO+BaO) / P is too large, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. ２ O ５ If the thickness is too small, the viscosity of the glass increases, which reduces productivity and tends to increase manufacturing costs.

[0052] ZnO is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component for adjusting the linear thermal expansion coefficient and refractive index of glass. It is also a component that can be involved in phase separation of glass. The ZnO content is preferably 0% or more, more than 0%, 0.5% or more, 1% or more, particularly 5% or more, and is 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. If the ZnO content is too high, glass phase separation is likely to occur. As a result, the homogeneity of the glass melt is likely to decrease and the glass tends to become unintentionally cloudy. Therefore, particularly when suppressing glass phase separation and reducing the risk of glass clouding, the ZnO content is preferably 3% or less, 2% or less, 1% or less, 0.5% or less, or particularly zero.

[0053] SnO ２ is a component that acts as a fining agent. It is also a component that adjusts the linear thermal expansion coefficient and refractive index of the glass. It is also a component that can be involved in the phase separation of the glass. ２ The content of SnO is preferably 0% or more, more 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, particularly preferably 0.15% or more. ２There is no particular upper limit to the content of SnO, but in reality it is 20%. If the content exceeds 20%, devitrification containing Sn will precipitate, which will increase the manufacturing load. ２ If the content is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass decreases, making the glass surface more likely to be altered. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired high transmittance.

[0054] ZrO ２ is a component that improves the Young's modulus and modulus of rigidity of glass. It is also a component that adjusts the thermal expansion coefficient and refractive index. It is also a component that can be involved in the phase separation of glass. ２ The content of ZrO is preferably 0% or more, more 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 is preferably 20% or less, 18% or less, 16% or less, 14% or less, 12% or less, particularly 6% or less. ２ If the content of ZrO is too high, devitrification increases, making it difficult to obtain glass having excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt decreases, making it difficult to melt, and the viscosity increases, making it difficult to refine, and in addition, molding of the glass becomes difficult, making it prone to lower productivity. ２ is easily mixed in as an impurity, ２ However, if an attempt is made to completely remove ZrO, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ The lower limit of the content is preferably 0.0001% or more, 0.001% or more, particularly preferably 0.01% or more.

[0055] HfO ２is a component that improves the Young's modulus and modulus of rigidity of the glass, and also a component that reduces the viscosity of the glass and improves the meltability and formability of the glass. It is also a component that can be involved in the phase separation of the glass. Depending on the application of the glass of the present invention, HfO ２ It is preferable to control the content of HfO and design it so as to obtain the desired mechanical strength. ２ If the content of HfO is too high, the mechanical strength of the glass becomes too high, making processing difficult and making it difficult to obtain glass with the desired surface condition and therefore the desired high transmittance. ２ As the raw materials for HfO are expensive, this leads to an increase in manufacturing costs. ２ The content of HfO 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 preferably 0.2% or less. ２ The lower limit of the content is not particularly limited and is 0% or more. ２ is a component that can be mixed in from the raw materials used, and the amount of the mixed in varies depending on the raw material composition. ２ In reality, the content may be 0.0001% or more, 0.0003% or more, and particularly 0.0005% or more.

[0056] Y ２ O ３ Y is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It is also a component that improves the Young's modulus of glass and adjusts the linear thermal expansion coefficient and refractive index. It is also a component that can be involved in the phase separation of glass. ２ O ３ The content of Y is preferably 0% or more, more than 0%, particularly preferably 0.1% or more, and is preferably 30% or less, 20% or less, particularly preferably 10% or less. ２ O ３If the content of Y is too high, the linear thermal expansion coefficient becomes too high, making it difficult to obtain glass with excellent heat resistance and thermal shock resistance. Furthermore, the homogeneity of the glass melt is likely to decrease. In addition, the chemical durability of the glass decreases, and the glass surface is likely to be altered. As a result, the surface irregularities deteriorate, making it difficult to obtain glass with the desired high transmittance. ２ O ３ is easily mixed in as an impurity, ２ O ３ If we try to completely eliminate Y, the raw material batch will become expensive and the manufacturing cost will tend to increase. ２ O ３ The lower limit of the content is preferably 0.0001% or more, 0.001% or more, particularly preferably 0.01% or more.

[0057] Pt is a component that can be mixed into glass in the form of ions, colloids, metal, etc., and causes a yellow to brown coloration. It is also a component that can contribute to 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. If the Pt content is too high, devitrification containing Pt may occur, increasing the production load. The lower limit of the Pt content is not particularly limited and may be 0%, but when using general melting equipment, the use of Pt components may be necessary to obtain homogeneous glass. Therefore, completely removing Pt tends to increase production costs. In the case where coloring is not adversely affected, the lower limit of the Pt content is preferably more than 0%, 0.0000001% or more, particularly 0.0000005% or more, in order to suppress an increase in production costs.

[0058] Rh is a component that can be mixed into glass in the form of ions, colloids, metal, etc., and causes a yellow to brown coloration. It is also a component that can contribute to 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 preferably 0.000005% or less. If the Rh content is too high, devitrification containing Rh may occur, increasing the production load. The lower limit of the Rh content is not particularly limited and may be 0%, but when using general melting equipment, the use of Rh components may be necessary to obtain homogeneous glass. Therefore, attempting to completely remove Rh tends to increase production costs. In the case where coloring is not adversely affected, the lower limit of the Rh content is preferably more than 0%, 0.0000001% or more, particularly 0.0000005% or more, in order to suppress an increase in production costs.

[0059] Furthermore, the total content of Pt + Rh (the total content of Pt and Rh) 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, particularly preferably 0.000005% or less. The lower limit of Pt + Rh is not particularly limited and may be 0%, but when using general melting equipment, the use of Pt and Rh components may be necessary to obtain a homogeneous glass. Therefore, completely removing Pt and Rh tends to increase production costs. In cases where coloring is not adversely affected, the lower limit of Pt + Rh is preferably greater than 0%, 0.0000001% or more, particularly preferably 0.0000005% or more, in order to suppress increases in production costs.

[0060] V ２ O ５ V is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can be involved in phase separation of glass. ２ O ５The content is preferably 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, particularly preferably 50 ppm or less. ２ O ５ If the content of V is too high, the meltability of the glass is likely to decrease. In addition, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. ２ O ５ is easily mixed in as an impurity, ２ O ５ If an attempt is made to completely remove V, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ O ５ The lower limit of the content of V is preferably more than 0, 1 ppm or more, 2 ppm or more, particularly preferably 3 ppm or more. ２ O ５ For example, when a colored appearance is required for a cooking top plate or the like, the content of V may be controlled to adjust the transmittance. ２ O ５ The content may be 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, particularly 7500 ppm or more.

[0061] Cr ２ O ３ is a component that reduces the viscosity of glass and improves the melting and formability of glass. It also absorbs light of various wavelengths and is a component that colors glass. It is also a component that can be involved in the phase separation of glass. ２ O ３The content of Cr is preferably 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, particularly preferably 50 ppm or less. ２ O ３ If the content of Cr is too high, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. In addition, devitrification containing Cr occurs, which increases the production load. ２ O ３ For example, when a colored appearance is required for a cooking top plate or the like, the content of Cr may be controlled to adjust the transmittance. ２ O ３ The content may be 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, particularly 3000 ppm or more.

[0062] Cr ２ O ３ and V ２ O ５ Cr is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It is also a component that colorizes glass by absorbing light of various wavelengths. When a black glass is desired for applications such as a cooking top plate, it is possible to add multiple coloring components. ２ O ３ and V ２ O ５ is a component that is particularly likely to contribute to the blackening of glass, and can further improve the jet blackness of glass. ２ O ３ +V ２ O ５ (Cr ２ O ３ and V ２ O ５The total content of Cr 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 particularly preferably 9000 ppm or more. ２ O ３ +V ２ O ５ If the content is too high, the melting property of the glass tends to decrease. ２ O ３ +V ２ O ５ The content is preferably 200,000 ppm or less, 100,000 ppm or less, 50,000 ppm or less, 30,000 ppm or less, 20,000 ppm or less, particularly preferably 10,000 ppm or less.

[0063] MoO ３ is a component that reduces the viscosity of glass and improves the meltability and formability of glass. It also absorbs light of various wavelengths and is a component that colors glass. It is also a component that can be involved in phase separation of glass. ３ The content of MoO is preferably 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, particularly preferably 50 ppm or less. ３ If the content of Mo is too high, the glass is likely to be colored, making it difficult to obtain glass with the desired high transmittance. In addition, devitrification containing Mo occurs, which increases the production load. ３ For example, when a colored appearance is required for a cooking top plate or the like, the content of MoO ３ The content may be 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, particularly 3000 ppm or more.

[0064] MnO ２MnO is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can be involved in phase separation of glass. ２ The content of MnO is preferably 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, particularly preferably 50 ppm or less. ２ If the content of MnO is too high, the meltability of the glass tends to decrease. In addition, the glass tends to be colored, making it difficult to obtain glass with a desired high transmittance. ２ is easily mixed in as an impurity, ２ However, if an attempt is made to completely remove MnO, the raw material batch becomes expensive and the manufacturing cost tends to increase. ２ The lower limit of the content of MnO is preferably more than 0 ppm, 1 ppm or more, 2 ppm or more, particularly preferably 3 ppm or more. ２ For example, when a colored appearance is required for a cooking top plate or the like, the content of MnO ２ The content may be 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, particularly 3000 ppm or more.

[0065] CoO is a component that, when incorporated in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of the glass. It also serves as a coloring component of glass, absorbing light of various wavelengths. It is also a component that can be involved in phase separation of glass. The CoO content is preferably 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 particularly preferably 50 ppm or less. If the CoO content is too high, the meltability of the glass is likely to decrease. Furthermore, the glass is likely to be colored, making it difficult to obtain glass with the desired high transmittance. However, because CoO is easily mixed in as an impurity, attempting to completely remove CoO tends to result in expensive raw material batches and increased manufacturing costs. To suppress increases in manufacturing costs, the lower limit of the CoO content is preferably more than 0 ppm, 1 ppm or more, 2 ppm or more, and particularly 3 ppm or more. The CoO content may be controlled to adjust the transmittance depending on the application of the glass of the present invention. For example, when a colored appearance is required for a cooking top plate or the like, the CoO content may be 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, and particularly 3000 ppm or more.

[0066] CuO is a component that, when incorporated in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of the glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can contribute to phase separation of glass. The CuO content is preferably 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 particularly preferably 50 ppm or less. If the CuO content is too high, the meltability of the glass is likely to decrease. Furthermore, the glass is likely to be colored, making it difficult to obtain glass with the desired high transmittance. However, because CuO is easily mixed in as an impurity, attempting to completely remove CuO tends to result in expensive raw material batches and increased manufacturing costs. To suppress increases in manufacturing costs, the lower limit of the CuO content is preferably more than 0 ppm, 1 ppm or more, 2 ppm or more, and particularly 3 ppm or more. Depending on the application of the glass of the present invention, the CuO content may be controlled to adjust the transmittance. For example, when a colored appearance is required for a cooking top plate or the like, the CuO content may be 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, and particularly 3000 ppm or more.

[0067] Nd ２ O ３ Nd is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the melting and formability of glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can be involved in phase separation of glass. ２ O ３ The content of Nd is preferably 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, particularly preferably 50 ppm or less. ２ O ３If the content of Nd is too high, the glass is likely to be colored, making it difficult to obtain glass with a desired high transmittance. ２ O ３ For example, when a colored appearance is required for a cooking top plate or the like, the content of Nd ２ O ３ The content may be 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, particularly 3000 ppm or more.

[0068] WO ３ is a component that, when contained in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can be involved in phase separation of glass. ３ The content of WO is preferably 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, particularly preferably 50 ppm or less. ３ If the content of WO is too high, the glass is likely to be colored, making it difficult to obtain glass with the desired high transmittance. ３ For example, when a colored appearance is required for a cooking top plate or the like, the content of WO ３ The content may be 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, particularly 3000 ppm or more.

[0069] NiO is a component that, when incorporated in an appropriate amount, reduces the viscosity of glass and improves the meltability and formability of the glass. It also absorbs light of various wavelengths and serves as a coloring component for glass. It is also a component that can contribute to phase separation of glass. The NiO content is preferably 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 particularly preferably 50 ppm or less. If the NiO content is too high, the meltability of the glass is likely to decrease. Furthermore, the glass is likely to be colored, making it difficult to obtain glass with the desired high transmittance. However, because NiO is easily mixed in from SUS components and the like during the manufacturing process, attempting to completely remove NiO tends to result in expensive raw material batches and increased manufacturing costs. To suppress increases in manufacturing costs, the lower limit of the NiO content is preferably more than 0 ppm, 1 ppm or more, 2 ppm or more, and particularly 3 ppm or more. The NiO content may be controlled to adjust the transmittance depending on the application of the glass of the present invention. For example, when a colored appearance is required for a cooking top plate or the like, the NiO content may be 100 ppm or more, 500 ppm or more, 800 ppm or more, 1000 ppm or more, 2000 ppm or more, and particularly 3000 ppm or more.

[0070] As ２ O ３ and Sb ２ O ３ is highly toxic and may pollute the environment during the glass manufacturing process and waste glass disposal. ２ O ３ +As ２ O ３ (Sb ２ O ３ and As ２ O ３The total content of the above (amount of the above and the total content of the above) is preferably 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, 10 ppm or less, 5 ppm or less, 1 ppm or less, and particularly preferably less than 1 ppm.

[0071] The glass of the present invention may further contain, in addition to the above components, SO 4 , provided that the desired chemical durability, transmittance, heat resistance, thermal shock resistance, etc. of the glass can be obtained. ３ , Cl ２ , La ２ O ３ , Ta ２ O ５ , Nb ２ O ５ , RfO ２ The total content of these components may be up to 10%. However, since raw material batches of the above components are expensive and tend to increase production costs, they may not be added unless there are special circumstances. The total content of these components is preferably 5% or less by mass, 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 preferably 0.045% or less.

[0072] The glass of the present invention may further contain, in addition to the above components, for example, H only when the desired chemical durability, transmittance, heat resistance, thermal shock resistance, etc. of the glass can be obtained. ２ , CO ２ , CO, H ２ O, He, Ne, Ar, N ２Trace components such as Ag, Au, Pd, Ir, Sc, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, and U may be contained up to 0.1% each. Furthermore, intentional 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 other elements have various catalytic properties, and their inclusion can impart unique functions to the glass. In light of these circumstances, when the purpose is to promote crystallization or to impart other functions, the above components may be contained in an amount of 1% or less, 0.5% or less, 0.3% or less, or 0.1% or less, respectively. When such a purpose is not particularly desired, the amount is preferably 500 ppm or less, 300 ppm or less, 100 ppm or less, and particularly preferably 10 ppm or less.

[0073] The glass of the present invention may be glass-ceramic. In this case, the content ranges of each component are the same as those described above. The crystal species in the glass-ceramic include Al. ２ SiO ５ , ZrO ２ etc.

[0074] A preferred composition range for implementing the glass of the present invention is, for example, in mass %: SiO ２ 45-80%, Al ２ O ３ 10-30%, B ２ O ３ Over 0 to 8%, Li ２ O 0-3%, TiO ２ More than 0 to 20%, P ２ O ５ It is 6.5 to 20%.

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

[0076] When the glass of the present invention is a crystallized glass, the glass having the above composition also makes it easier to achieve a low coefficient of linear expansion and excellent light transmittance.

[0077] The glass of the present invention has a density of 2.20 to 3.50 g / cm ３ , 2.30~3.40g / cm ３ , 2.40~3.35g / cm３ , 2.50~3.30g / cm ３ , particularly 2.55 to 3.25 g / cm ３ If the density is too low, the gas permeability of the glass increases, and there is a risk of the glass being contaminated during long-term storage. On the other hand, if the density is too high, the weight per unit area increases, making handling difficult.

[0078] The glass of the present invention preferably has a β-OH value of more than 0 to 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, or 0.08 to 0.71 / mm, particularly 0.08 to 0.7 / mm. If the β-OH value is too low, the amount of water vapor generated during melting of the glass batch decreases. This reduces the stirring action of the glass batch due to the generation of water vapor, making it difficult to promote the initial reaction of the glass batch and increasing the production load. On the other hand, if the β-OH value is too high, bubbles are more likely to form at the interface between the molten glass and a metal component such as Pt or a refractory component, resulting in a deterioration in the quality of the glass product. Furthermore, the glass transition point, yield point, strain point, annealing point, and softening point decrease, and the linear thermal expansion coefficient increases, potentially deteriorating the heat resistance and thermal shock resistance, making the glass unsuitable for use at high temperatures. The β-OH value varies depending on the raw materials used, the melting atmosphere, the melting temperature, the melting time, and other factors, and can be adjusted as needed by changing these conditions. For example, the β-OH value can be increased by increasing the amount of hydroxide in the raw materials, melting by burner heating, or increasing the melting temperature. Furthermore, the β-OH value can be increased by extending the melting time in a sealed container and by shortening the melting time in an unsealed container.

[0079] The glass of the present invention has a linear thermal expansion coefficient of 60×10 at 30 to 380°C. －７ / ℃ or less, 56 x 10 －７ / ℃ or less, 52 × 10 －７ / ℃ or less, 48 ​​x 10 －７ / ℃ or less, 44 x 10 －７ / ℃ or less, 40 x 10 －７ / ℃ or less, 36 x 10 －７ / ℃ or less, 34 x 10 －７ / ℃ or less, 32 × 10 －７ / ℃ or less, 29.5 × 10 －７ / ℃ or less, 27.5 × 10 －７ / ℃ or less, 25.5 × 10 －７ / ℃ or less, 23.5 × 10 －７ / ℃ or less, 21.5 × 10 －７ / ℃ or less, 19.5 × 10 －７ / ℃ or less, 18 x 10 －７ / ℃ or less, 17.5 × 10 －７ / ℃ or less, 17 x 10 －７ / ℃ or less, 16.5 × 10 －７ / ℃ or less, 15.5 × 10 －７ / ℃ or less, 15 × 10 －７ / ℃ or less, 14.5 × 10 －７ / ℃ or less, 14 × 10 －７ / °C or less, especially 13.5 × 10 －７ / °C or less is preferred.

[0080] The glass of the present invention has a linear thermal expansion coefficient of 60×10 at 30 to 750° C. －７ / ℃ or less, 56 x 10 －７ / ℃ or less, 52 × 10 －７ / ℃ or less, 48 ​​x 10 －７ / ℃ or less, 44 x 10 －７ / ℃ or less, 40 x 10 －７ / ℃ or less, 36 x 10 －７ / ℃ or less, 34 × 10 －７ / ℃ or less, 32 × 10 －７ / ℃ or less, 29.5 × 10 －７ / ℃ or less, 27.5 × 10 －７ / ℃ or less, 25.5 × 10 －７ / ℃ or less, 23.5 × 10 －７ / ℃ or less, 21.5 × 10 －７ / ℃ or less, 19.5 × 10 －７ / ℃ or less, 18 x 10 －７ / ℃ or less, 17.5 × 10 －７ / ℃ or less, 17 x 10 －７ / ℃ or less, 16.5 × 10 －７ / ℃ or less, 15.5 × 10 －７ / ℃ or less, 15 × 10 －７ / ℃ or less, 14.5 × 10 －７ / ℃ or less, 14 × 10 －７ / °C or less, especially 13.5 × 10 －７ / °C or less is preferred.

[0081] If the linear thermal expansion coefficient is too high, the heat resistance and thermal shock resistance will be low, making it difficult to use at high temperatures. In addition, it will be difficult to apply to applications requiring positional stability. In particular, when it is expected to be used as a cooking top plate, a low linear thermal expansion coefficient is preferable to avoid damage due to heat or distortion. There is no particular lower limit for the linear thermal expansion coefficient, but in reality, the linear thermal expansion coefficient at 30 to 380°C should be -70 x 10 －７ / °C or higher, and the linear thermal expansion coefficient at 30 to 750°C is -60 x 10 －７ / °C or higher.

[0082] In the glass of the present invention, the temperature at which the slope of the thermal expansion curve of the glass changes is regarded as the glass transition point (glass transition temperature). The glass of the present invention preferably has a glass transition point of 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 preferably 730°C or higher. If the glass transition point is too low, the glass will flow too much, making it difficult to mold into a desired shape. Furthermore, if the glass transition point is too low, the glass will be 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 at temperatures equal to or higher than the glass transition point is regarded as the deformation point. The glass of the present invention preferably has a deformation point of 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 preferably 770°C or higher. If the deformation point is too low, the glass will flow too much, making it difficult to mold into a desired shape. Furthermore, if the deformation point is too low, the glass will be prone to deformation when used at high temperatures.

[0084] The liquidus temperature of the glass of the present invention is preferably 1600° C. or less, 1580° C. or less, 1560° C. or less, 1540° C. or less, 1520° C. or less, 1500° C. or less, 1480° C. or less, 1460° C. or less, 1440° C. or less, 1420° C. or less, 1410° C. or less, 1400° C. or less, 1380° C. or less, 1360° C. or less, 1340° C. or less, 1320° C. or less, 1300° C. or less, 1290° C. or less, 1280° C. or less, 1270° C. or less, 1260° C. or less, 1250° C. or less, 1240° C. or less, 1230° C. or less, 1200° C. or less, 1190° C. or less, particularly preferably 1180° C. or less. If the liquidus temperature is too high, devitrification tends to occur during production. On the other hand, if the temperature is 1480°C or lower, it becomes easy to manufacture using the roll method, etc., if the temperature is 1410°C or lower, it becomes easy to manufacture using the overflow method, etc., if the temperature is 1350°C or lower, it becomes easy to manufacture using the bushing method, etc., and if the temperature is 1300°C or lower, it becomes easy to manufacture using the Danner method, etc.

[0085] The glass of the present invention has a liquidus viscosity (logarithm of viscosity corresponding to the liquidus temperature) of 1.6 or more, 1.70 or more, 1.75 or more, 1.80 or more, 1.85 or more, 1.90 or more, 1.95 or more, 2.00 or more, 2.05 or more, 2.10 or more, 2.15 or more, 2.20 or more, 2.25 or more, 2.30 or more, 2.35 or more, 2.40 or more, 2.45 or more, 2.50 or more, 2.55 or more, 2.60 or more Preferably, the liquidus viscosity is 2.65 or more, 2.70 or more, 2.75 or more, 2.80 or more, 2.85 or more, 2.90 or more, 2.95 or more, 3.00 or more, 3.05 or more, 3.10 or more, 3.15 or more, 3.20 or more, 3.25 or more, 3.30 or more, 3.35 or more, 3.40 or more, 3.45 or more, 3.50 or more, 3.55 or more, 3.60 or more, 3.65 or more, particularly 3.70 or more. If the liquidus viscosity is too low, devitrification tends to occur during production. On the other hand, if the liquidus viscosity is 3.40 or more, production by a roll method or the like is facilitated, if the liquidus viscosity is 3.50 or more, production by a casting method or the like is facilitated, and if the liquidus viscosity is 3.70 or more, production by an overflow method or the like is facilitated.

[0086] For applications requiring high transmittance in the infrared region, the glass of the present invention preferably has a transmittance at a wavelength of 1200 nm and a thickness of 4 mm 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. In particular, for use in infrared communication applications such as infrared cameras and remote controls, a high transmittance at a wavelength of 1200 nm is preferred. On the other hand, for applications requiring low transmittance in the infrared region, the transmittance at a thickness 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. In particular, when used for blocking infrared light, a low transmittance at a wavelength of 1200 nm is preferable. Note that the preferred transmittance varies depending on the application, and is not limited to the specific numerical range described above.

[0087] For applications requiring high transmittance in the near-infrared region, the glass of the present invention preferably has a transmittance at a wavelength of 800 nm and a thickness of 4 mm 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. In particular, for use in medical applications such as vein authentication, a high transmittance at a wavelength of 800 nm is preferred. On the other hand, for applications requiring low transmittance in the near-infrared region, the transmittance at a thickness of 4 mm and a wavelength of 800 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. In particular, when used in chemical containers or for blocking visible light, or when a colored appearance is required for top plates of cooking appliances, etc., a low transmittance at a wavelength of 800 nm is preferable. Note that the preferred transmittance varies depending on the application, and is not limited to the specific numerical range described above.

[0088] For applications requiring high transmittance in the visible range, the glass of the present invention preferably has a transmittance at a wavelength of 555 nm and a thickness of 4 mm 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. A wavelength of around 555 nm is a wavelength range in which humans easily perceive light as brightness, and a high transmittance at a wavelength of 555 nm is particularly preferred for applications requiring high brightness, such as displays. On the other hand, for applications requiring low transmittance in the visible range, the transmittance at a wavelength of 555 nm and a thickness of 4 mm 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. In particular, when used in applications such as chemical containers or blocking ultraviolet to green light, or when a colored appearance is required for top plates for cooking appliances, a low transmittance at a wavelength of 555 nm is preferred. Note that the preferred transmittance varies depending on the application, and is not limited to the specific numerical ranges described above.

[0089] For applications requiring high transmittance in the near-ultraviolet region, the glass of the present invention preferably has a transmittance at a wavelength of 380 nm and a thickness of 4 mm 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. In particular, for applications requiring colorless transparency, such as displays, a high transmittance at a wavelength of 380 nm is preferred. If the transmittance at a wavelength of 380 nm is too low, the glass will be colored yellow, making it difficult to achieve the desired colorless transparency. On the other hand, for applications requiring low transmittance in the near-ultraviolet region, the transmittance at a wavelength of 380 nm and a thickness of 4 mm 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. In particular, when used in chemical containers or for blocking ultraviolet to blue light, or when a colored appearance is required for top plates for cooking appliances, a low transmittance at a wavelength of 380 nm is preferred. Note that the preferred transmittance varies depending on the application, and is not limited to the specific numerical range described above.

[0090] The transmittance of the glass of the present invention should be suitably controlled for each wavelength depending on the application. Specifically, in applications requiring high light transmittance in the ultraviolet region, the transmittance at a thickness of 4 mm and a wavelength of 300 nm is preferably 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. In particular, when used in UV curing of resins, fluorescence detection of printed matter, insect attraction, and the like, a high transmittance at a wavelength of 300 nm is preferred. On the other hand, in applications requiring low light transmittance in the ultraviolet region, the transmittance at a thickness of 4 mm and a length of 300 nm is preferably 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. In particular, when UV blocking ability is required for chemical containers, optical filters, etc., a low transmittance at a wavelength of 300 nm is preferred. Note that the preferred transmittance varies depending on the application, and is not limited to only the specific numerical range described above.

[0091] Lightness L of the glass of the present invention ＊ should be suitably controlled depending on the application. In applications where high brightness is required, the brightness L ＊ is preferably 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, 85 or more, 90 or more, 94 or more, 95 or more, 96 or more, 96.1 or more, 96.3 or more, and particularly preferably 96.5 or more. ＊ If the lightness L is too small, the color will tend to appear grayish and dark regardless of the chromaticity. Therefore, in applications where high brightness is required, such as displays, it is important to ＊ On the other hand, in applications where low brightness is required, the brightness L ＊ Preferably, the lightness L is 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, 20 or less, 15 or less, and particularly preferably 10 or less. In particular, when the material is used for chemical containers or visible light blocking applications, or when a black appearance is required for top plates for cooking appliances, the lightness L ＊ It is preferable that the lightness L＊ Since varies depending on the application, it is not limited to the specific numerical ranges described above.

[0092] For the glass of the present invention, in applications requiring high colorless transparency, the chromaticity a ＊ is preferably within ±50, ±40, ±30, ±20, ±10, ±5, ±3, ±1, ±0.9, ±0.8, ±0.7, ±0.6, and particularly preferably within ±0.5. ＊ If the chromaticity a is too large in the negative direction, it tends to appear green, and if it is too large in the positive direction, it tends to appear red. On the other hand, if it is necessary to color it deeply green or red, the chromaticity a at a thickness of 4 mm is ＊ It is preferable that the chromaticity a at a thickness of 4 mm is ±6 or more, ±7 or more, ±8 or more, particularly ±9 or more. ＊ is preferably +10 or more, +12 or more, +14 or more, +16 or more, +17 or more, +18 or more, +19 or more, and particularly preferably +20 or more. ＊ Since varies depending on the application, it is not limited to the specific numerical ranges described above.

[0093] For the glass of the present invention, in applications where high colorless transparency is required, the chromaticity b ＊ is preferably within ±50, ±45, ±40, ±30, ±20, ±10, ±5, ±3, ±1, ±0.9, ±0.8, ±0.7, ±0.6, and particularly preferably within ±0.5. ＊ If the value is too large in the negative direction, the color tends to appear blue, and if it is too large in the positive direction, the color tends to appear yellow. On the other hand, if it is necessary to color the color deeply blue or yellow, the chromaticity b ＊ It is preferable that the chromaticity b at a thickness of 4 mm is ±6 or more, ±7 or more, ±8 or more, particularly ±9 or more. ＊is preferably +10 or more, +12 or more, +16 or more, +20 or more, +24 or more, +28 or more, +32 or more, +36 or more, +40 or more, +42 or more, +44 or more, +46 or more, +48 or more, and particularly preferably +50 or more. ＊ Since varies depending on the application, it is not limited to the specific numerical ranges described 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 preferably 1 nm or less. If the surface roughness Ra is too large, light incident on the glass surface from the outside is likely to be scattered, and light is less likely to be emitted from the inside of the glass to the outside of the glass, making it difficult to obtain glass with the desired high transmittance. The glass is also more likely to break. On the other hand, if the flat surface roughness Ra is too small, the glass surface is more likely to become charged, increasing the attractive force between the glass and an object in contact with the glass surface, which may make it difficult to obtain the desired mold releasability. Furthermore, the charging of the glass surface may make it difficult to obtain the desired electrical responsiveness. In consideration of the above circumstances, the flat surface roughness Ra 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 in the form of a plate, 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 preferably 1 nm or less. If the surface roughness Ra of the end face is too large, it becomes difficult for light to enter the glass from the end face of the glass into the glass, and it becomes difficult for light to exit from the inside of the glass to the outside of the glass, making it difficult to obtain glass with the desired high transmittance. In addition, the glass is more likely to break. On the other hand, if the surface roughness Ra of the end face is too small, when attempting to physically support the glass at the end face of the glass, the contact area between the glass and the support becomes small, reducing frictional resistance and potentially making it difficult to reliably support the glass. In view of the above circumstances, 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 preferably 0.01 μm or less. If the waviness is too large, a distribution is likely to occur in the angle of incidence of light incident on the glass surface at a specific position, the amount of light scattering on the glass surface increases on average, and it becomes difficult to obtain glass with the desired high transmittance. There is no particular limitation on the lower limit of the waviness, but in reality it is 0.01 nm or more.

[0097] The surface roughness Ra of the main surface and edge surface of the glass can be measured by a method conforming to JIS B0601:2001. The waviness can be measured using a stylus-type surface profiler in accordance with SEMI STD D15-1296 "Method for measuring surface waviness of FPD glass substrates." The thickness can be measured using common devices such as digital calipers or a point-contact roughness meter.

[0098] Generally, when spinodal decomposition (a phase separation pattern in which secondary and subsequent phases exist in an intricate manner within the first phase with the largest volume fraction and are continuously mixed) occurs, unevenness easily develops on the glass surface due to differences in the chemical durability of each phase. After extensive research, the inventors discovered that annealing the glass of the present invention at a temperature above its glass transition point can cause phase separation into two or more distinct phases, and found that in many cases, this phase separation results in binodal decomposition (a phase separation pattern in which secondary and subsequent phases are scattered within the first phase with the largest volume fraction and mixed in globular or other shapes). Furthermore, they discovered that by appropriately controlling the glass composition, annealing conditions, and the like, phase separation due to binodal decomposition can be optionally manifested, resulting in a glass surface with a desired transmittance. For these reasons, the glass of the present invention may be composed of only a single glass phase, or may contain two or more phases. It is particularly preferable that the glass of the present invention contain two or more phases when a white or milky white appearance is required, for example, for use as a cooking top plate. In this case, glass with a white or milky white appearance can be easily obtained by appropriately controlling the annealing conditions, etc. The second and subsequent phases may be in a glassy, ​​crystalline, gaseous, or liquid state. Furthermore, the second and subsequent phases may be composed of metal oxides, metals, organic substances, etc., and their compositions are not limited. Furthermore, the shapes of the second and subsequent phases are preferably sheet-like, granular, spherical, circular, elliptical, linear, etc., and may be any of these shapes alone or in combination. The phase separation can be monitored by measuring the surface shape using a scanning electron microscope (SEM) or atomic force microscope (AFM) after etching with a liquid such as hydrofluoric acid. Furthermore, FT-IR spectroscopy, Raman spectroscopy, etc. can be used to confirm the chemical bonding state in a sample and obtain information about phase separation nondestructively. The phase separation described in this specification can be monitored by methods readily conceivable by those skilled in the art.

[0099] The size of the second and subsequent phases 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 preferably 0.1 μm or less, at the longest part. If the longest part of the second and subsequent phases is too long, the surface roughness of the glass increases, making it difficult to obtain glass with the desired high transmittance. Note that the lower limit of the longest part of each of the second and subsequent phases is not particularly limited, but in practice it is 0.01 nm or more.

[0100] When the second and subsequent phases are crystalline, the crystal system is preferably one of hexagonal, trigonal, cubic, tetragonal, orthorhombic, or monoclinic. A triclinic system is also acceptable, but in this case, birefringence is likely to occur within the crystal, resulting in light scattering and making it difficult to obtain glass with the desired high transmittance. In the case of a triclinic system, the composition of the first phase must be designed so that the difference in refractive index between the crystal and the first phase is small.

[0101] When the glass of the present invention contains two or more phases, if the difference in refractive index between the second or subsequent phases and the first phase is large, light will be scattered at the boundaries between the phases, making it difficult to obtain a glass with the desired high transmittance. The difference in refractive index between the phases should be 1.5 or less at each of the typical 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). Preferably, the refractive index of each phase is 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 particularly preferably within 0.0001. The refractive index of each phase can be measured using a precision refractometer (KPR-2000 manufactured by Shimadzu Corporation) or the like.

[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, particularly 1.53 or less. It is also 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, particularly 1.43 or more. If the refractive index is too high, light may be scattered at the surface or end face, making it difficult to obtain a glass with the desired high transmittance. On the other hand, if the refractive index is too low, the difference in refractive index between the glass of the present invention and air may be small, making it difficult to visually recognize the glass of the present invention and making it difficult to handle during production.

[0103] The glass of the present invention preferably has an unpolished surface. The theoretical strength of glass is inherently very high, but it often breaks even at stresses far lower than the theoretical strength. This is because nano-scale defects called Griffith flows occur on the glass surface during processes after glass molding, such as a polishing process. Therefore, if the surface of the glass of the present invention is unpolished, the inherent mechanical strength is less likely to be impaired, and the glass is less likely to break. Furthermore, the polishing process can be omitted, thereby reducing manufacturing costs. For example, when the glass of the present invention is in a plate shape, the glass of the present invention becomes even more resistant to breakage if the entire effective surfaces of both main faces are unpolished. Furthermore, in order to make the entire effective surface an unpolished surface, it is effective to make the portion corresponding to the effective surface a free surface at the time of molding. Furthermore, even if the portion corresponding to the effective surface comes into contact with a solid member or the like during molding, a smooth surface similar to a free surface can be created by reheating the portion that came into contact with the solid member or the like after molding at a temperature above the glass transition point.

[0104] The 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 preferably 4 mm or less. If the sample thickness is too large, the attenuation rate of light inside the glass increases, making it difficult to obtain glass with the desired high transmittance. Furthermore, when the glass of the present invention is used for displays, the thickness is preferably 1000 μm or less, 500 μm, 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 preferably 5 to 10 μm.

[0105] The difference between the maximum thickness and the minimum thickness of the glass of the present invention is preferably 50 μm or less, 25 μm or less, 10 μm or less, 5 μm or less, 1 μm or less, 500 nm or less, 300 nm or less, 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 preferably 1 nm or less. If the difference between the maximum thickness and the minimum thickness is too large, the angle of incidence of light incident from either the front or back surface will differ from the angle of emergence when emitted from the other surface, resulting in undesirable light scattering and a glaring appearance.

[0106] The glass of the present invention preferably has high water resistance, which is a typical chemical durability. Specifically, when the amount of alkali elution is measured by a method in accordance with JIS R3502 (1995), the amount of Li ２ O, Na ２ O.K. ２ Preferably, the amounts of O eluted are 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 preferably 0.003 mg or less. If the water resistance is low, ion exchange between alkali metals and protons or the like on the glass surface is likely to proceed, and the portions where ion exchange has progressed are altered, making them more susceptible to cracking and the like.

[0107] The glass of the present invention may be subjected to chemical strengthening or the like. The conditions for chemical strengthening treatment may be appropriately selected by taking into consideration the glass composition, the volume fraction of each phase, the type of molten salt, etc., and the treatment time and treatment temperature. For example, in order to facilitate chemical strengthening, Na, which may be contained in the remaining glass phase, may be added. ２ A glass composition containing a large amount of O may be selected. The molten salt may contain monovalent cations such as Li, Na, and K, or divalent cations such as Mg, Ca, Sr, Ba, and Zn, either singly or in combination. Furthermore, in addition to the usual single-stage strengthening, multi-stage chemical strengthening may be selected. Examples of molten salts that can be used include 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.), and combinations thereof. Nitrates with low melting points are preferred, with sodium nitrate being particularly preferred. The ion exchange temperature is preferably 330 to 550°C, 350 to 500°C, and particularly 390 to 450°C. The ion exchange time is preferably 30 minutes to 12 hours, or 45 minutes to 10 hours. The above strengthening conditions may be changed as desired depending on the required application and strength, and the preferred conditions are not necessarily limited to those described above.

[0108] When compressive stress is imparted to the glass of the present invention by 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, particularly preferably 300 MPa or more. If the compressive stress value is too small, there is a risk that the Vickers hardness and bending strength will be low.

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

[0110] The glass of the present invention preferably has a scratch four-point bending strength of 150 MPa or more, 200 MPa or more, 235 MPa or more, 245 MPa or more, particularly 250 MPa or more. If the scratch four-point bending strength is too low, the glass will be prone to breakage when dropped when used as a smartphone cover glass, etc. The upper limit of the scratch four-point bending strength is not particularly limited, but in reality it is 1500 MPa or less. The scratch four-point bending strength can be measured by the following procedure. First, a glass plate processed to 50 mm x 50 mm x 0.6 mm thick is placed vertically, and 1.5 mm thick SUS plates are placed on the main surface and the opposite surface of the glass plate to fix the glass plate. The tip of a pendulum-shaped arm is collided with the glass plate through P180 grit sandpaper to scratch it. The tip of the arm is an iron cylinder with a diameter of 5 mm, and the arm weighs 550 g. The arm is swung down 5 mm from the impact point. The four-point bending strength of the damaged glass plate is measured.

[0111] In addition, even when the glass of the present invention is crystallized glass, it preferably has the same properties as those described above. The shape of the glass of the present invention is usually plate-like (particularly flat), but is not limited thereto and may be appropriately selected depending on the application.

[0112] Next, the method for producing the glass of the present invention will be described.

[0113] The method for producing glass of the present invention includes a step of melting glass raw materials to obtain molten glass, and a step of shaping the molten glass. Specifically, first, a raw material batch (glass raw materials) prepared to obtain glass of the above composition is charged into a glass melting furnace and melted at 1200 to 1800°C to obtain molten glass, which is then shaped. When melting the glass, any one of the following melting methods may be used, or a combination of two or more of them may be used: a flame melting method using a burner or the like, an electric melting method using electrical heating, a melting method using laser irradiation, a melting method using plasma, a liquid phase synthesis method, and a vapor phase synthesis method.

[0114] The forming method is preferably at least one selected from the group consisting of an overflow method, a float method, a downdraw method, a slot-down method, a redraw method, a containerless method, a blow method, a press method, a roll method, a bushing method, and a tube drawing method. After forming, the glass may be reheated at a temperature equal to or higher than the glass transition point. In this way, the glass of the present invention having good surface quality can be produced.

[0115] When forming by the overflow method, the viscosity of the glass at the bottom end of the trough-shaped refractory is 10 ３．５ ~10 ５．０ dPa·s is preferred. If no force is applied to the lower apex portion of the trough-shaped structure, the glass will fall downward while shrinking due to surface tension. To prevent this, it is necessary to pinch both sides of the glass material with rollers and stretch it in the width direction so that the glass material does not shrink. When forming the glass of the present invention, since the heat quantity of the glass itself is small, the cooling rate of the glass increases rapidly the moment it leaves the trough-shaped refractory. Therefore, the viscosity of the glass at the lower apex portion of the trough-shaped refractory is preferably 10 ５．０ dPa・s or less, 10 ４．８ dPa・s or less, 10 ４．６ dPa・s or less, 10 ４．４ dPa・s or less, 10 ４．２ dPa·s or less, especially 10 ４．０ In this way, when a tensile stress is applied in the width direction, it is possible to widen the sheet width while preventing breakage, and it is also possible to stably stretch the sheet downward.

[0116] Next, the obtained glass is annealed. The purpose of annealing is mainly to remove distortion and residual stress. In this case, it is preferable to heat treat the glass by staying in a temperature range from room temperature to the strain point (≈glass transition point -5 to -20°C) for at least 1 minute, more preferably 3 minutes or more, 16 minutes or more, and most preferably more than 30 minutes. This makes it easier to obtain glass composed of only a single glass phase, resulting in increased chemical durability of the glass, making it easier to control the glass surface as desired, and making it easier to obtain glass with a desired high transmittance. On the other hand, annealing may also form phase separation in the glass in addition to removing distortion and residual stress. In this case, it is preferable to heat treat the glass by staying in a temperature range higher than the strain point for at least 1 minute, more preferably 3 minutes or more, 16 minutes or more, and most preferably more than 30 minutes. This allows the glass to undergo phase separation, and in many cases, the phase separation state becomes binodal decomposition. Note that when the glass of the present invention is phase separated, SiO ２ The glass is divided into a first phase rich in α- and other secondary and subsequent phases, but the chemical durability of the secondary and subsequent phases is often lower than that of the first phase. In such cases, unevenness is likely to occur on the glass surface due to differences in the chemical durability of each phase. However, by designing the glass to the preferred composition described above, the unevenness can be suppressed to a level that allows the desired transmittance to be obtained. Furthermore, imparting fine unevenness can improve the releasability of the glass of the present invention from objects that come into contact with the glass. In addition, increasing the surface area of ​​the glass surface compared to the free surface state can increase frictional force and physical and chemical adsorption, leading to higher functionality of the glass of the present invention. Annealing may also be performed while applying or irradiating sound waves or electromagnetic waves.

[0117] As mentioned above, when a white or milky white appearance is required for applications such as cooking top plates, the glass of the present invention is preferably subjected to phase separation into two or more phases. To obtain glass having such a white or milky white appearance, the formed glass of the present invention is preferably heat-treated by staying at a temperature higher than the strain point for at least one minute. Specifically, the heat treatment temperature is preferably 700°C or higher, 800°C or higher, 850°C or higher, and particularly 900°C or higher, and is preferably 1500°C or lower, 1200°C or lower, or 1100°C or lower. If the heat treatment temperature is too high, the glass will change from a solid state to a molten state, making it difficult to obtain the desired shape. On the other hand, if the heat treatment temperature is too low, it becomes difficult to efficiently promote phase separation, which ultimately leads to increased production costs. The heat treatment time is preferably 1 minute or more, 1 hour or more, 5 hours or more, 10 hours or more, 20 hours or more, and particularly preferably 24 hours or more, and is preferably 1000 hours or less, 500 hours or less, 100 hours or less, or 50 hours or less. If the heat treatment time is outside the above range, it will be difficult to obtain glass having the desired properties.

[0118] Furthermore, the cooling rate when cooling the glass of the present invention after heating to a high temperature may be a specific temperature gradient, or may be two or more levels of temperature gradient. To obtain sufficient thermal shock resistance, it is desirable to control the cooling rate to sufficiently relax the structure of the remaining glass phase. In this case, the average cooling rate from the maximum 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 preferably 5°C / min or less, in the inner part of the glass farthest from the surface of the glass of the present invention. Furthermore, to obtain long-term dimensional stability, it is more preferably 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 preferably 0.01°C / min or less. Except when physical tempering treatments such as air cooling or water cooling are performed, it is desirable that the cooling rate of the glass surface is close to the cooling rate of the inner wall, farthest from the glass surface. The value obtained by dividing the cooling rate of the inner part of the glass farthest from the surface by the cooling rate of the surface is preferably 0.0001 to 1, 0.001 to 1, 0.01 to 1, 0.1 to 1, 0.5 to 1, 0.8 to 1, or 0.9 to 1, and particularly 1. A value close to 1 makes it difficult for residual strain to occur at all positions in the glass of the present invention, making it easier to achieve long-term dimensional stability. The cooling rate of the surface can be estimated using a contact thermometer or a radiation thermometer. The temperature inside the glass can be estimated from the numerical data obtained by immersing the glass at a high temperature in a cooling medium and measuring the heat quantity and rate of heat change of the cooling medium, as well as the specific heat and thermal conductivity of the glass and the cooling medium.

[0119] The glass of the present invention thus obtained may be cut. For example, when cutting using a wire saw, it is preferable to cut the glass while supplying a slurry containing abrasive grains to the wire saw.

[0120] The method may also include a step of subjecting the glass obtained in the step of forming the molten glass to heat treatment to crystallize it. Specifically, crystallized glass can be obtained by heat-treating the annealed glass to 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°C to 1300°C (preferably 850°C to 1100°C) for 0.1 to 50 hours (preferably 0.2 to 10 hours, more preferably 0.25 to 5 hours). The heat treatments in each of the nucleation and crystal growth steps may be performed only at a specific temperature, or may be held at two or more temperatures and heat-treated stepwise, or may be heated while applying a temperature gradient. Alternatively, only the heat treatment for crystal growth may be performed without performing nucleation. By doing so, for example, crystallized glass can be obtained in which the following crystals are precipitated. Specifically, Al ２ SiO ５ (aluminum silicate), zirconia, zirconia titanate, tin-containing zirconia-based oxide, titania, aluminotitanate, β-quartz solid solution, α-quartz, β-quartz, β-spodumene solid solution, spodumene, zircon, cordierite, enstatite, mica, nepheline, anorthite, lithium disilicate, lithium metasilicate, wollastonite, diopsite, cristobalite, tridymite, feldspar, spinel-based crystals, metal colloids, etc. Only one type of these crystals may be contained, or two or more types may be contained.

[0121] In addition, crystals can be precipitated by annealing, and crystallization can be promoted by applying or irradiating sound waves or electromagnetic waves.Furthermore, the cooling rate when cooling the crystallized glass of the present invention that has been heated to a high temperature can be a specific temperature gradient, or can be two or more levels of temperature gradient.The cooling rate is preferably the same as the cooling rate of the above-mentioned glass.

[0122] The present invention will now be described based on examples, but the present invention is not limited to the following examples. Tables 1 to 32 show the compositions and property values ​​of glasses according to the examples of the present invention (samples No. 1 to 80).

[0123]

[0124]

[0125]

[0126]

[0127]

[0128]

[0129]

[0130]

[0131]

[0132]

[0133]

[0134]

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155] First, each raw material was mixed in the form of oxide, hydroxide, carbonate, nitrate, etc. to obtain a glass having the composition shown in each table, thereby obtaining a glass batch (the compositions shown in Table 1 are the analytical values ​​of the actually produced glass. The analysis was performed using a RIGAKU ZSX series scanning X-ray fluorescence analyzer). The obtained glass batch was melted at 1200 to 1800°C for 0.5 to 400 hours, and the obtained molten glass was rolled by a roll method while cooling, and formed into a width of 100 mm and a thickness of 5 mm. Subsequently, the glass was heat-treated in an annealing furnace at a glass transition temperature of -150 to -50°C for 30 minutes, and the temperature of the annealing furnace was lowered to room temperature at a rate of -100°C / h, thereby obtaining glasses Nos. 1 to 80.

[0156] The prepared glass samples were processed by physical polishing, chemical polishing, chemical etching, fire blasting, etc. to prepare evaluation samples for β-OH value, viscosity, liquidus temperature, liquidus viscosity, density, linear thermal expansion coefficient, Young's modulus, modulus of rigidity, Poisson's ratio, etc., and evaluations were performed. The obtained molten glass was formed into a length of 400 mm by the overflow method, and heat-treated in an annealing furnace at the glass transition point of −150 to −50°C for 30 minutes. The annealing furnace was then cooled to room temperature at a rate of −100°C / h to obtain a glass plate. The surface roughness Ra of the main surface, the surface roughness Ra of the edge surface, and the waviness of the obtained glass plate were measured.

[0157] The Pt and Rh contents of the prepared samples were analyzed using an ICP-MS device (Agilent 8800 manufactured by AGILEINT TECHNOLOGY) as follows. First, the prepared glass sample was crushed and wetted with pure water, and then perchloric acid, nitric acid, sulfuric acid, hydrofluoric acid, etc. were added to melt the sample. Thereafter, the Pt and Rh contents of the sample were measured by ICP-MS (inductively coupled plasma mass spectrometry). The Pt and Rh contents of each measurement sample were determined based on a calibration curve created using a previously prepared Pt and Rh solution of known concentration. The measurement mode was Pt:He gas / HMI (low mode), Rh:HEHe gas / HMI (medium mode), and the mass numbers were Pt: 198 and Rh: 103. In addition, the Li content of the prepared sample was ２ The O content was analyzed using an atomic absorption spectrometer (ContrAA600 manufactured by Analytik Jena). The procedure for melting the glass sample and the use of calibration curves were basically the same as in the analysis of Pt and Rh. Regarding other components, Pt, Rh, Li ２ The content of each component was measured by ICP-MS or atomic absorption spectrometry in the same manner as in Example 1. Alternatively, a glass sample with a known concentration previously determined using an ICP-MS or atomic absorption spectrometry analyzer was used as a calibration curve sample, and a calibration curve was created using an XRF (X-ray fluorescence) analyzer (ZSX Primus IV manufactured by RIGAKU). Based on the calibration curve, the actual content of each component was determined from the XRF analysis value of the measurement sample. During the XRF analysis, the tube voltage, tube current, exposure time, etc. were adjusted as needed depending on the components being analyzed.

[0158] The density was evaluated by the Archimedes method.

[0159] The β-OH value was determined by measuring the transmittance of the glass using an infrared spectrophotometer (FT-IR Frontier manufactured by Perkin Elmer) and using the following formula: The scanning speed was 100 μm / min and the sampling pitch was 1 cm. －１ The number of scans was 10 per measurement.

[0160] β-OH value = (1 / X) log (T １ / T ２ ) X: Glass thickness T1: Reference wave number 3846 cm －１ T2: OH group absorption wave number 3600 cm －１Minimum transmittance near

[0161] The linear thermal expansion coefficient was evaluated as the average linear thermal expansion coefficient measured in the temperature ranges of 30 to 380°C and 30 to 750°C using a sample processed to 20 mm x 3.8 mmφ. A NETZSCH dilatometer was used for the measurement. The same measuring device was also used to measure the thermal expansion curve of the glass sample in the temperature range of 30 to 750°C, and the glass transition point and yield point were evaluated by calculating the inflection point.

[0162] The high-temperature viscosity was evaluated by the platinum ball pulling method as follows. A lump glass sample was crushed to an appropriate size and placed in an alumina crucible. The alumina crucible was then heated to melt the sample, and the viscosity of the glass was measured at multiple temperatures. The constants of the Vogel-Fulcher equation were calculated to create a viscosity curve. The viscosity of each viscosity (10 ４ dPa·s, 10 ３．５ dPa·s, 10 ３ dPa·s, 10 ２．５ dPa·s and 10 ２ The temperature at which the viscosity of the material is 100 dPa·s was calculated.

[0163] The liquidus temperature was evaluated by the following method. First, a platinum boat of approximately 120 × 20 × 10 mm was filled with glass powder aligned to 300 to 500 micrometers, placed in an electric furnace, and melted at 1400 to 1800 ° C for 30 minutes. The platinum boat was then transferred to an electric furnace with a linear temperature gradient and held there for 20 hours to precipitate devitrification. The measurement sample was air-cooled to room temperature, and the devitrification precipitated at the interface between the platinum boat and the glass was observed. The temperature at the devitrification point was calculated from the temperature gradient graph of the electric furnace to determine the liquidus temperature. The obtained liquidus temperature was then interpolated into the high-temperature viscosity curve of the glass, and the viscosity corresponding to the liquidus temperature was evaluated as the liquidus viscosity.

[0164] Transmittance, brightness, and chromaticity were evaluated using a spectrophotometer using a 4 mm thick sample with a surface roughness equivalent to optical polishing. A JASCO V-670 spectrophotometer was used for the measurements. The V-670 was equipped with an integrating sphere unit, the ISN-723, and the measured transmittance corresponds to total light transmittance. The measurement wavelength range was 200 to 2500 nm, the scan speed was 200 nm / min, the sampling pitch was 1 nm, and the bandwidth was 5 nm in the wavelength range from 200 to 800 nm and 20 nm in other wavelength ranges. Prior to measurement, baseline correction (100% alignment) and dark measurement (0% alignment) were performed. Dark measurement was performed with the barium sulfate plate attached to the ISN-723 removed. Using the measured transmittance, tristimulus values ​​XYZ were calculated based on JIS Z8781-42013 and corresponding international standards, and lightness and chromaticity were calculated from each stimulus value (illuminant C / 10°).

[0165] The surface roughness Ra of the main surface and end surface of the glass was measured by a method in accordance with JIS B0601:2001.

[0166] The waviness was measured using a stylus-type surface profilometer to determine the filtered centerline waviness (WCA) as specified in JIS B0601:2001. This measurement was performed in accordance with SEMI STD D15-1296, "Method for measuring surface waviness of FPD glass substrates." The cutoff during measurement was 0.8 to 8 mm, and the measurement was performed over a length of 300 mm in a direction perpendicular to the rolling direction of the glass during forming.

[0167] The color appearance was judged visually.

[0168] The glasses of Example Nos. 1 to 80 of the present invention were materials with a low coefficient of linear thermal expansion and high heat resistance and thermal shock resistance. Nos. 1 to 22, 24 to 48, 51 to 52, and 77 to 80 were colorless and transparent. Nos. 23, 49 to 50, and 53 to 76 were colored black or slightly brown.

[0169] The glass of the present invention is preferably used for a top plate for a cooker, a fire window, heat-resistant tableware, or a building material. Specifically, the glass of the present invention is suitable for, for example, front windows for oil stoves, wood stoves, etc., substrates for high-tech products such as color filters and image sensor substrates, setters for firing electronic components, light diffusion plates, furnace tubes for semiconductor manufacturing, masks for semiconductor manufacturing, optical lenses, components for dimension measurement, communication components, building materials, chemical reaction vessels, top plates for electromagnetic cooking, heat-resistant tableware, heat-resistant covers, window glass for fire doors, components for astronomical telescopes, components for space optics, colorants, light-absorbing materials, temperature adjusting materials, sound-insulating materials, dielectric materials, linear thermal expansion coefficient adjusting materials, battery components, components for improving the strength of resins, etc., display components, chemical strengthening components, etc. Furthermore, when the glass of the present invention is a crystallized glass, it is preferably used for a top plate for a cooker, a fire window, heat-resistant tableware, or a building material. The applications of the glass of the present invention with a low linear thermal expansion coefficient are not limited to those mentioned above. The above-mentioned applications may be used alone or in combination with each other, such as a top plate for an electromagnetic cooktop with a display function or a smartphone with a chemically strengthened display.

Claims

1. SiO ２ 45-80%, Al ２ O ３ 10-30%, B ２ O ３ 0-12%, Li ２ A glass containing 0 to 5% O.

2. P by mass% ２ O ５ 2. The glass of claim 1, containing greater than 0%.

3. TiO ２ 3. The glass according to claim 1, wherein the glass contains more than 0%.

4. B in mass% ２ O ３ 0 to 8%, Li ２ O 0-3%, P ２ O ５ 4. The glass according to claim 3, containing 6.5 to 20%.

5. Fe, by mass% ２ O ３ 3. The glass according to claim 1, wherein the glass contains more than 0%.

6. HfO (mass%) ２ 3. The glass according to claim 1, further comprising not more than 10% of Cr.

7. The glass according to claim 1 or 2, characterized in that it contains, by mass%, Pt 0.05% or less and Rh 0.05% or less.

8. SnO (by mass%) ２ 3. The glass according to claim 1, wherein the glass contains more than 0%.

9. The glass according to claim 1 or 2, characterized in that it contains, by mass%, 12.5% ​​or less of ZnO.

10. Li, by mass% ２ O+Na ２ O+K ２ 3. The glass according to claim 1, containing up to 15% O.

11. ZrO, by mass% ２ 3. The glass according to claim 1, wherein the glass contains more than 0%.

12. In mass%, (P２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５ 3. The glass according to claim 1, wherein the saturation temperature is 0.01 or more.

13. P, by mass% ２ O ５ ×TiO ２ 3. The glass according to claim 1, wherein the refractive index is 0.22 or more.

14. By mass%, MgO + CaO + SrO + BaO 5.9% or less, Li ２ O+Na ２ O+K ２ O 2.6% or less, P ２ O ５ ×TiO ２ 3. The glass according to claim 1, wherein the refractive index is 0.01 or more.

15. The linear thermal expansion coefficient at 30 to 750°C is 60 x 10 －７ 3. The glass according to claim 1, wherein the temperature is 0.15 to 1.0° C.

16. The glass according to claim 1 or 2, characterized in that it has a thickness of 4 mm and a transmittance of 0.1% or more at a wavelength of 555 nm.

17. The glass according to claim 1 or 2, which is used for a top plate for a cooking appliance, a fireproof window, heat-resistant tableware or a building component.

18. SiO ２ 45-80%, Al ２ O ３ 10-30%, B ２ O ３ 0-12%, P ２ O ５ More than 0 to 20%, MgO+CaO+SrO+BaO 0 to 5%, Li ２ O+Na ２ O+K ２ O 0 to 5%; (P ２ O ５ ×TiO ２ ) / (Al ２ O ３ +P ２ O ５) is 1.4 or more, and the linear thermal expansion coefficient at 30 to 750 ° C. is 40 × 10 －７ / °C or less.

19. SiO ２ 45-80%, Al ２ O ３ 10-30%, B ２ O ３ 0-12%, P ２ O ５ 0 to 20%, Li ２ O 5% or less, ZrO ２ More than 0 to 20%, MgO + CaO + SrO + BaO 0 to 8%, Li ２ O+Na ２ O+K ２ O 0-2.9%, (MgO+CaO+SrO+BaO) / P ２ O ５ 3.8 or less, and the linear thermal expansion coefficient at 30 to 750°C is 40 x 10 －７ / °C or less.

20. By mass%, TiO ２ 20. The glass of claim 18 or 19, containing more than 0%.

21. The linear thermal expansion coefficient at 30 to 380°C and 30 to 750°C is 5 to 40 x 10 －７ / °C, a thickness of 4 mm, and a transmittance at a wavelength of 555 nm of 0.1% or more.

22. A method for producing the glass according to claim 1 or 2, comprising: a step of melting glass raw materials to obtain molten glass; and a step of shaping the molten glass, wherein the method for shaping the molten glass is at least one method selected from the group consisting of an overflow method, a float method, a downdraw method, a slot-down method, a redraw method, a containerless method, a blow method, a press method, a roll method, a bushing method, and a tube drawing method.