Li2O-Al2O3-SiO2 crystallized glass

Abstract

The present invention provides a Li2O-Al2O3-SiO2-based crystallized glass that maintains transparency while suppressing yellow discoloration caused by TiO2, Fe2O3, etc. [Solution] A Li2O-Al2O3-SiO2 crystalline glass characterized by containing less than 0.5% TiO2 by mass and having a β-OH value of 0.001 to 2 / mm.

Description

[Technical Field]

[0001] The present invention relates to Li2O-Al2O3-SiO2 crystallized glass. More specifically, the present invention relates to Li2O-Al2O3-SiO2 crystallized glass suitable as a material for, for example, front windows of oil stoves and wood-burning stoves, substrates for high-tech products such as color filters and substrates for image sensors, setters for firing electronic components, light diffusers, furnace tubes for semiconductor manufacturing, masks for semiconductor manufacturing, optical lenses, dimensional measuring members, communication members, building members, containers for chemical reactions, top plates for induction cookers, heat-resistant tableware, heat-resistant covers, window glass for fire doors, members for astronomical telescopes, and members for space optics. [Background technology]

[0002] Conventionally, Li2O-Al2O3-SiO2 crystallized glass has been used as a material for front windows of oil stoves and wood-burning stoves, substrates for high-tech products such as color filters and substrates for image sensors, setters for firing electronic components, light diffusers, furnace tubes for semiconductor manufacturing, masks for semiconductor manufacturing, optical lenses, dimensional measuring components, communication components, building components, containers for chemical reactions, top plates for induction cookers, heat-resistant tableware, heat-resistant covers, window glass for fire doors, components for astronomical telescopes, and components for space optics. For example, Patent Documents 1 to 3 disclose Li2O-Al2O3-SiO2 crystallized glass obtained by precipitating Li2O-Al2O3-SiO2 crystals such as β-quartz solid solution (Li2O·Al2O3·nSiO2 [where 2≦n≦4]) or β-spodumene solid solution (Li2O·Al2O3·nSiO2 [where n≧4]) as the main crystal.

[0003] Li2O-Al2O3-SiO2 crystallized glass has excellent thermal properties due to its low coefficient of thermal expansion and high mechanical strength. Furthermore, by appropriately adjusting the heat treatment conditions during the crystallization process, it is possible to control the type of precipitated crystals, and transparent crystallized glass (with precipitated β-quartz solid solution) can be easily produced.

[0004] Incidentally, the production of this type of crystallized glass requires melting at temperatures exceeding 1400°C. For this reason, the clarifying agents added to the glass batch are As2O3 and Sb2O3, which generate large amounts of clarifying gas when melted at high temperatures. However, As2O3 and Sb2O3 are highly toxic and can contaminate the environment during the glass manufacturing process and the disposal of waste glass.

[0005] Therefore, SnO2 and Cl have been proposed as alternative clarifying agents to As2O3 and Sb2O3 (see, for example, Patent Documents 4 and 5). However, Cl can easily corrode molds and metal rolls during glass molding, which may result in a deterioration of the glass surface quality. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 39-21049 [Patent Document 2] Special Publication No. 40-20182 [Patent Document 3] Japanese Patent Application Publication No. 1-308845 [Patent Document 4] Japanese Patent Application Publication No. 11-228180 [Patent Document 5] Japanese Patent Application Publication No. 11-228181 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Furthermore, Li2O-Al2O3-SiO2 crystallized glass has a yellowish tint due to discoloration caused by TiO2 and Fe2O3, which is undesirable in appearance. To improve the yellow discoloration of transparent crystallized glass, the TiO2 content should be reduced. However, reducing the TiO2 content slows down the nucleation rate during the crystallization process, making it easier for fewer nuclei to be generated. As a result, there are more coarse crystals, causing the crystallized glass to become cloudy and impairing its transparency.

[0008] The object of the present invention is to provide a Li2O-Al2O3-SiO2-based crystallized glass that suppresses yellow discoloration caused by TiO2, Fe2O3, etc., while ensuring transparency. [Means for solving the problem]

[0009] The inventors have found that the deficiency in crystal nucleation resulting from a reduction in TiO2 content can be compensated for by increasing the water content.

[0010] The Li2O-Al2O3-SiO2 crystallized glass of the present invention is characterized by containing less than 0.5% TiO2 by mass and having a β-OH value of 0.001 to 2 / mm. Even if the TiO2 content is reduced to less than 0.5% to improve the yellow coloration, it is possible to sufficiently crystallize the glass by making the β-OH value 0.001 / mm or higher. The "β-OH value" refers to the value obtained by measuring the transmittance of the glass using FT-IR and using the following formula.

[0011] β-OH value = (1 / X)log(T1 / T2) X: Glass thickness (mm) T1: Reference wavelength 3846cm -1 Transmittance (%) T2: Hydroxyl group absorption wavelength 3600 cm -1 Minimum transmittance in the vicinity (%)

[0012] The Li2O-Al2O3-SiO2 crystalline glass of the present invention preferably further contains, by mass%, SiO2 40-90%, Al2O3 5-30%, Li2O 1-10%, SnO2 0-20%, ZrO2 1-20%, MgO 0-10%, P2O 50-10%, and Sb2O3 + As2O 30-2%.

[0013] As described above, even if the combined amount of the clarifying agents Sb2O3 and As2O3 is kept to less than 2%, the glass can be sufficiently clarified by keeping the β-OH value below 2 / mm. Note that "Sb2O3+As2O3" refers to the combined amount of Sb2O3 and As2O3.

[0014] The Li2O-Al2O3-SiO2 crystalline glass of the present invention preferably further contains, by mass%, 0-10% Na2O, 0-10% K2O, 0-10% CaO, 0-10% SrO, 0-10% BaO, 0-10% ZnO, and 30-10% B2O.

[0015] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably further contains Fe2O3 0.1% or less by mass.

[0016] In the Li2O-Al2O3-SiO2 crystalline glass of the present invention, it is preferable that the mass ratio of SnO2 / (SnO2+ZrO2+P2O5+TiO2+B2O3) is 0.06 or higher. Here, "SnO2 / (SnO2+ZrO2+P2O5+TiO2+B2O3)" is the value obtained by dividing the SnO2 content by the total amount of SnO2, ZrO2, P2O5, TiO2, and B2O3.

[0017] In the Li2O-Al2O3-SiO2 crystalline glass of the present invention, it is preferable that the mass ratio of Al2O3 / (SnO2+ZrO2) is 7.1 or less. Here, "Al2O3 / (SnO2+ZrO2)" is the value obtained by dividing the Al2O3 content by the total amount of SnO2 and ZrO2.

[0018] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a mass ratio of SnO2 / (SnO2+ZrO2) of 0.01 to 0.99. Here, "SnO2 / (SnO2+ZrO2)" is the value obtained by dividing the SnO2 content by the total amount of SnO2 and ZrO2.

[0019] The Li2O-Al2O3-SiO2 crystalline glass of the present invention preferably contains 8% or less of Na2O+K2O+CaO+SrO+BaO by mass. Here, "Na2O+K2O+CaO+SrO+BaO" refers to the combined amount of Na2O, K2O, CaO, SrO, and BaO.

[0020] In the Li2O-Al2O3-SiO2 crystalline glass of the present invention, it is preferable that the mass ratio of (SiO2 + Al2O3) / Li2O is 20 or more. Here, "(SiO2 + Al2O3) / Li2O" is the value obtained by dividing the total amount of SiO2 and Al2O3 by the amount of Li2O.

[0021] In the Li2O-Al2O3-SiO2 crystalline glass of the present invention, it is preferable that the mass ratio of (SiO2 + Al2O3) / SnO2 is 44 or higher. Here, "(SiO2 + Al2O3) / SnO2" is the value obtained by dividing the total amount of SiO2 and Al2O3 by the amount of SnO2.

[0022] In the present invention, the Li2O-Al2O3-SiO2 crystalline glass preferably has a mass ratio of (MgO+ZnO) / Li2O of less than 0.395 or greater than 0.754. Here, "MgO+ZnO) / Li2O" is the value obtained by dividing the total amount of MgO and ZnO by the amount of Li2O.

[0023] In the present invention, the Li2O-Al2O3-SiO2 crystalline glass preferably has a mass ratio of (Li2O+Na2O+K2O) / ZrO2 of 2.0 or less. Here, "(Li2O+Na2O+K2O) / ZrO2" is the value obtained by dividing the total amount of Li2O, Na2O, and K2O by the amount of ZrO2.

[0024] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a mass ratio of TiO2 / ZrO2 of 0.0001 to 5.0. Here, "TiO2 / ZrO2" is the value obtained by dividing the TiO2 content by the ZrO2 content.

[0025] In the Li2O-Al2O3-SiO2-based crystallized glass of the present invention, the mass ratio of TiO2 / TiO2+Fe2O3 is preferably 0.001 to 0.999. Here, "TiO2 / (TiO2+Fe2O3)" is the value obtained by dividing the TiO2 content by the total amount of TiO2 and Fe2O3.

[0026] The Li2O-Al2O3-SiO2 crystalline glass of the present invention preferably contains less than 0.05% by mass of HfO2 + Ta2O5. Here, "HfO2 + Ta2O5" refers to the combined amount of HfO2 and Ta2O5.

[0027] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably contains Pt at a concentration of 7 ppm or less by mass.

[0028] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably contains Rh 7 ppm or less by mass%.

[0029] The Li2O-Al2O3-SiO2 crystalline glass of the present invention preferably contains 9 ppm or less of Pt+Rh by mass. Here, "Pt+Rh" refers to the total amount of Pt and Rh.

[0030] The Li2O-Al2O3-SiO2 crystallized glass of the present invention is preferably colorless and transparent in appearance.

[0031] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a thickness of 3 mm and a transmittance of 10% or more at a wavelength of 300 nm. This allows for suitable use in various applications requiring ultraviolet transmittance.

[0032] In the Li2O-Al2O3-SiO2-based crystallized glass of the present invention, it is preferable that a β-quartz solid solution precipitates as the main crystal. This makes it easier to obtain a crystallized glass with a low coefficient of thermal expansion.

[0033] In the Li2O-Al2O3-SiO2 crystallized glass of the present invention, the coefficient of thermal expansion at 30 to 380°C is 30 × 10⁻¹⁰ -7 It is preferable that the temperature is below / ℃. In this way, it can be suitably used in various applications where low expansion is required.

[0034] In the Li2O-Al2O3-SiO2 crystallized glass of the present invention, the coefficient of thermal expansion at 30 to 750°C is 30 × 10⁻⁶. -7 It is preferable that the temperature is below / °C. This allows for suitable use in various applications where low expansion is required over a wide temperature range.

[0035] In the Li2O-Al2O3-SiO2 crystallized glass of the present invention, it is preferable that the change in transmittance before and after crystallization at a thickness of 3 mm and a wavelength of 300 nm is 50% or less. Here, "change in transmittance before and after crystallization" means {(transmittance before crystallization (%) - transmittance after crystallization (%)) / transmittance before crystallization (%)} × 100 (%).

[0036] In the Li2O-Al2O3-SiO2 crystalline glass of the present invention, the mass ratio of Al2O3 / (Li2O+(1 / 2×(MgO+ZnO)) is preferably 3.0 to 8.0. Here, "Al2O3 / (Li2O+(1 / 2×(MgO+ZnO))" is the value obtained by dividing the Al2O3 content by the sum of the Li2O content and the combined amount of MgO and ZnO divided by 2.

[0037] The Li2O-Al2O3-SiO2 crystalline glass of the present invention is characterized by containing more than 30% MoO by mass and having a β-OH value of 0.001 to 0.5 / mm. [Effects of the Invention]

[0038] According to the present invention, it is possible to provide a Li2O-Al2O3-SiO2-based crystallized glass that suppresses yellow discoloration caused by TiO2, Fe2O3, etc., while ensuring transparency. [Brief explanation of the drawing]

[0039] [Figure 1] This is the transmittance curve of sample No. 27 before crystallization. [Figure 2] This is the transmittance curve of sample No. 27 after crystallization. [Figure 3] This graph shows the relationship between the β-OH value and density of samples A to E. [Figure 4] This graph shows the relationship between the β-OH value and density of samples F through J. [Figure 5] This graph shows the relationship between the β-OH value and density of samples K to M. [Modes for carrying out the invention]

[0040] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention is characterized by containing less than 0.5% TiO2 by mass and having a β-OH value of 0.001 to 2 / mm.

[0041] First, the glass composition of the Li2O-Al2O3-SiO2 crystallized glass of the present invention will be described. In the following descriptions of the content of each component, unless otherwise specified, "%" means "mass%".

[0042] TiO2 is a nucleating component that precipitates crystals during the crystallization process. On the other hand, when present in large quantities, it significantly intensifies the coloration of the glass. In particular, zirconia titanate crystals containing ZrO2 and TiO2 act as crystal nuclei, but electrons transition from the valence band of the ligand oxygen to the conduction band of the central metals zirconia and titanium (LMCT transition), which contributes to the coloration of the crystallized glass. Furthermore, if titanium remains in the residual glass phase, an LMCT transition can occur from the valence band of the SiO2 framework to the conduction band of the tetravalent titanium in the residual glass phase. Also, a dd transition occurs in the trivalent titanium of the residual glass phase, which contributes to the coloration of the crystallized glass. In addition, when titanium and iron are present together, an ilmenite (FeTiO3)-like coloration appears. It is also known that when titanium and tin are present together, the yellow color intensifies. Therefore, the TiO2 content is preferably less than 0-0.5%, 0-0.48%, 0-0.46%, 0-0.44%, 0-0.42%, 0-0.4%, 0-0.38%, 0-0.36%, 0-0.34%, 0-0.32%, 0-0.3%, 0-0.28%, 0-0.26%, 0-0.24%, 0-0.22%, 0-0.2%, 0-0.18%, 0-0.16%, 0-0.14%, 0-0.12%, and especially preferably 0-0.1%. However, since TiO2 is easily mixed in as an impurity, attempting to completely remove TiO2 tends to increase the cost of the raw material batch and thus the manufacturing cost. To suppress increases in manufacturing costs, the lower limit of the TiO2 content is preferably 0.0003% or more, 0.0005% or more, 0.001% or more, 0.005% or more, 0.01% or more, and especially 0.02% or more.

[0043] In addition to the above components, the Li2O-Al2O3-SiO2-based crystallized glass of the present invention may also contain the following components in its glass composition.

[0044] SiO2 forms the framework of the glass and is a component of the Li2O-Al2O3-SiO2 crystal system. The SiO2 content is preferably 40-90%, 52-80%, 55-75%, 56-70%, 59-70%, 60-70%, 60-69.5%, 60.5-69.5%, 61-69.5%, 61.5-69.5%, 62-69.5%, 62.5-69.5%, 63-69.5%, and especially preferably 63.5-69.5%. If the SiO2 content is too low, the coefficient of thermal expansion tends to be high, making it difficult to obtain crystallized glass with excellent thermal shock resistance. Also, chemical durability tends to decrease. On the other hand, if the SiO2 content is too high, the meltability of the glass decreases, the viscosity of the glass melt increases, making it difficult to clarify and mold the glass, which tends to reduce productivity. Furthermore, the crystallization process takes longer, which can easily lead to decreased productivity.

[0045] Al2O3 forms the skeleton of the glass and is a component of the Li2O-Al2O3-SiO2 crystal system. Furthermore, Al2O3 coordinates around the crystal nucleus, forming a core-shell structure. The presence of this core-shell structure makes it difficult for crystal nucleus components to be supplied from outside the shell, thus preventing the crystal nucleus from becoming enlarged and facilitating the formation of numerous minute crystal nuclei. The preferred Al2O3 content is 5-30%, 8-30%, 9-28%, 10-27%, 12-27%, 14-27%, 16-27%, 17-27%, 18-27%, 18-26.5%, 18.1-26.5%, 19-26.5%, 19.5-26.5%, 20-26.5%, 20.5-26.5%, and particularly 20.8-25.8%. If the Al2O3 content is too low, the coefficient of thermal expansion tends to be high, making it difficult to obtain crystallized glass with excellent thermal shock resistance. Chemical durability also tends to decrease. Furthermore, crystal nuclei become larger, making the crystallized glass more prone to clouding. On the other hand, if the Al2O3 content is too high, the meltableness of the glass decreases, the viscosity of the glass melt increases, making clarification difficult, and glass molding becomes difficult, leading to decreased productivity. Additionally, mullite crystals tend to precipitate, causing devitrification of the glass and making the crystallized glass more fragile.

[0046] Li2O is a component that makes up the Li2O-Al2O3-SiO2 system crystal, and it greatly affects crystallinity, as well as reducing the viscosity of the glass and improving its meltability and moldability. The Li2O content is preferably 1-10%, 2-10%, 2-8%, 2.5-6%, 2.8-5.5%, 2.8-5%, 3-5%, 3-4.5%, 3-4.2%, and especially preferably 3.2-4%. If the Li2O content is too low, mullite crystals tend to precipitate, causing the glass to devitrify. Also, when crystallizing the glass, it becomes difficult for Li2O-Al2O3-SiO2 system crystals to precipitate, making it difficult to obtain crystallized glass with excellent thermal shock resistance. Furthermore, the meltability of the glass decreases, the viscosity of the glass melt increases, making it difficult to clarify and mold the glass, which tends to reduce productivity. On the other hand, if the Li2O content is too high, the crystallinity becomes too strong, making the glass prone to devitrification and making the crystallized glass more susceptible to breakage.

[0047] SiO2, Al2O3, and Li2O are the main components of the β-quartz solid solution, which is the main crystal. Li2O and Al2O3 compensate for each other's charges, allowing them to solid-solve in the SiO2 framework. By including these three components in a suitable ratio, crystallization proceeds efficiently, enabling low-cost production. The mass ratio of (SiO2 + Al2O3) / Li2O is preferably 20 or more, 20.2 or more, 20.4 or more, 20.6 or more, 20.8 or more, and especially 21 or more.

[0048] SnO2 is a component that acts as a clarifying agent. It is also a necessary component for efficiently precipitating crystals in the crystallization process. On the other hand, if present in large quantities, it significantly intensifies the coloration of the glass. SnO2 content is found in the following ranges: 0-20%, over 0-20%, 0.05-20%, 0.1-10%, 0.1-5%, 0.1-4%, 0.1-3%, 0.15-3%, 0.2-3%, 0.2-2.7%, 0.2-2.4%, 0.25-2.4%, 0.3-2.4%, 0.35-2.4%, 0.4-2.4%, 0.45-2.4%, 0.5-2.4%, and 0. The preferred SnO2 content is 5-2.35%, 0.5-2.3%, 0.5-2.2%, 0.5-2.1%, 0.5-2.05%, 0.5-2%, 0.5-1.95%, 0.5-1.93%, 0.5-1.91%, 0.5-1.9%, 0.5-1.88%, 0.5-1.85%, 0.5-1.83%, 0.5-1.81%, and particularly preferably 0.5-1.8%. If the SnO2 content is too low, it becomes difficult to clarify the glass, and productivity tends to decrease. Also, crystal nuclei may not be formed sufficiently, and coarse crystals may precipitate, causing the glass to become cloudy or break. On the other hand, if the SnO2 content is too high, the coloration of the crystallized glass may become too strong. Also, the amount of SnO2 evaporation during melting increases, which tends to increase the environmental burden.

[0049] ZrO2 is a nucleating component that causes crystals to precipitate during the crystallization process. The ZrO2 content is as follows: 1-20%, 1-15%, 1-10%, 1-5%, 1.5-5%, 1.75-4.5%, 1.75-4.4%, 1.75-4.3%, 1.75-4.2%, 1.75-4.1%, 1.75-4%, 1.8-4%, 1.85-4%, 1.9-4%, 1.95-4%, 2-4%, 2.05-4%. The preferred ZrO2 content is 2.1-4%, 2.15-4%, 2.2-4%, 2.25-4%, 2.3-4%, 2.3-3.95%, 2.3-3.95%, 2.3-3.9%, 2.3-3.85%, 2.3-3.8%, over 2.7-3.8%, 2.8-3.8%, 2.9-3.8%, and especially 3-3.8%. If the ZrO2 content is too low, crystal nuclei will not be sufficiently formed, and coarse crystals may precipitate, potentially causing the crystallized glass to become cloudy or break. On the other hand, if the ZrO2 content is too high, coarse ZrO2 crystals will precipitate, making the glass more prone to devitrification and the crystallized glass more likely to break.

[0050] TiO2 and ZrO2 are components that can function as crystal nuclei. Ti and Zr are congener elements and have similar electronegativity and ionic radius. For this reason, they tend to adopt similar molecular conformations as oxides, and it is known that phase separation in the initial stages of crystallization is likely to occur in the presence of both TiO2 and ZrO2. For this reason, within the range in which coloration is acceptable, the TiO2 / ZrO2 mass ratio is preferably 0.0001~5.0, 0.0001~4.0, 0.0001~3.0, 0.0001~2.5, 0.0001~2.0, 0.0001~1.5, 0.0001~1.0, 0.0001~0.5, 0.0001~0.4, and particularly preferably 0.0001~0.3. If the TiO2 / ZrO2 ratio is too small, the raw material batch tends to become expensive, and manufacturing costs tend to increase. On the other hand, if the TiO2 / ZrO2 ratio is too high, the crystal nucleation rate will slow down, which can increase manufacturing costs.

[0051] The amount of SnO2+ZrO2 is preferably 1-30%, 1.1-30%, 1.1-27%, 1.1-24%, 1.1-21%, 1.1-20%, 1.1-17%, 1.1-14%, 1.1-11%, 1.1-9%, 1.1-7.5%, 1.4-7.5%, 1.8-7.5%, 2.0-7.5%, 2.2-7%, 2.2-6.4%, 2.2-6.2%, 2.2-6%, 2.3-6%, 2.4-6%, 2.5-6%, and especially preferably 2.8-6%. If the amount of SnO2+ZrO2 is too low, crystal nuclei will not precipitate easily, making crystallization difficult. On the other hand, if the amount of SnO2+ZrO2 is too high, the crystal nuclei will become larger, and the crystallized glass will be more prone to becoming cloudy.

[0052] SnO2 has the effect of promoting phase separation in glass. In order to efficiently generate phase separation while keeping the liquidus temperature low (while suppressing the risk of devitrification due to initial phase precipitation), and to rapidly carry out nucleation and crystal growth in subsequent processes, the mass ratio of SnO2 / (SnO2+ZrO2) is preferably 0.01~0.99, 0.01~0.98, 0.01~0.94, 0.01~0.90, 0.01~0.86, 0.01~0.82, 0.01~0.78, 0.01~0.74, 0.01~0.70, 0.03~0.70, and especially 0.05~0.70.

[0053] Furthermore, at high temperatures, SnO2 undergoes the reaction SnO2 → SnO + 1 / 2O2, releasing O2 gas into the glass melt. This reaction is known as a clarification mechanism for SnO2, and the O2 gas released during the reaction not only has a "defoaming effect" that enlarges the fine bubbles present in the glass melt and releases them outside the glass system, but also a "stirring effect" that mixes the glass melt. In the Li2O-Al2O3-SiO2 crystallized glass of the present invention, SiO2 and Al2O3 account for the majority of the content, and since these components are sparingly soluble, it is necessary to include these three components in suitable ratios in order to efficiently form a homogeneous glass melt. The mass ratio of (SiO2 + Al2O3) / SnO2 is preferably 44 or more, 44.3 or more, 44.7 or more, 45 or more, 45.2 or more, 45.4 or more, 45.6 or more, 45.8 or more, and especially 46 or more.

[0054] The Al2O3 / (SnO2+ZrO2) ratio is preferably 7.1 or less, 7.05 or less, 7.0 or less, 6.95 or less, 66.9 or less, 6.85 or less, 6.8 or less, 6.75 or less, 6.7 or less, 6.65 or less, 6.6 or less, 6.55 or less, 6.5 or less, 6.45 or less, 6.4 or less, 6.35 or less, 6.3 or less, 6.25 or less, 6.2 or less, 6.15 or less, 6.1 or less, 6.05 or less, 6.0 or less, 5.98 or less, 5.95 or less, 5.92 or less, 5.9 or less, 5.8 or less, 5.7 or less, 5.6 or less, and especially preferably 5.5 or less. If the Al2O3 / (SnO2+ZrO2) ratio is too large, nucleation will not proceed efficiently, and efficient crystallization will be difficult. On the other hand, if the Al2O3 / (SnO2+ZrO2) ratio is too small, the crystal nuclei become larger, and the crystallized glass tends to become cloudy. For this reason, it is preferable that the lower limit of Al2O3 / (SnO2+ZrO2) be 0.01 or higher.

[0055] MgO is a component that dissolves in Li2O-Al2O3-SiO2 crystals and increases the thermal expansion coefficient of Li2O-Al2O3-SiO2 crystals. The MgO content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0.02-3.5%, 0.05-3.5%, 0.08-3.5%, 0.1-3.5%, 0.1-3.3%, 0.1-3%, 0.13-3%, 0.15-3%, 0.17-3%, 0.19-3%, 0.2-2.9%, 0.2-2.7%, 0.2-2.5%, 0.2-2.3%, 0.2-2.2%, 0.2-2.1%, and particularly preferably 0.2-2%. If the MgO content is too low, the coefficient of thermal expansion tends to become too low. Also, volume contraction occurs during crystallization, but the amount of this volume contraction may become too large. Furthermore, the difference in the coefficient of thermal expansion between the crystalline phase and the remaining glass phase after crystallization becomes large, which can make the crystallized glass more prone to breakage. If the MgO content is too high, the crystallinity becomes too strong, making it prone to devitrification and the crystallized glass more prone to breakage. Also, the coefficient of thermal expansion tends to become too high.

[0056] P2O5 is a component that suppresses the precipitation of coarse ZrO2 crystals. The P2O5 content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4%, 0-3.5%, 0.02-3.5%, 0.05-3.5%, 0.08-3.5%, 0.1-3.5%, 0.1-3.3%, 0.1-3%, 0.13-3%, 0.15-3%, 0.17-3%, 0.19-3%, 0.2-2.9%, 0.2-2.7%, 0.2-2.5%, 0.2-2.3%, 0.2-2.2%, 0.2-2.1%, 0.2-2%, and especially preferably 0.3-1.8%. If the P2O5 content is too low, coarse ZrO2 crystals may precipitate, causing the glass to devitrify easily and making the crystallized glass more prone to breakage. On the other hand, if the P2O5 content is too high, the amount of Li2O-Al2O3-SiO2 crystal precipitation decreases, and the coefficient of thermal expansion tends to increase.

[0057] Na2O is a component that can be dissolved in Li2O-Al2O3-SiO2 crystals, significantly affecting crystallinity and reducing the viscosity of the glass, thereby improving its meltability and moldability. It is also a component used to adjust the thermal expansion coefficient and refractive index of crystallized glass. The preferred Na2O content is 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0-3%, 0-2.7%, 0-2.4%, 0-2.1%, 0-1.8%, and especially 0-1.5%. If the Na2O content is too high, the crystallinity becomes too strong, making the glass prone to devitrification and the crystallized glass more susceptible to breakage. Furthermore, the ionic radius of Na cations is larger than that of Li cations and Mg cations, which are components of the main crystal, and they are not easily incorporated into the crystal, so Na cations tend to remain in the residual glass (glass matrix) after crystallization. Therefore, if the Na2O content is too high, a difference in refractive index between the crystalline phase and the residual glass is likely to occur, and the crystallized glass tends to become cloudy. However, since Na2O is easily introduced as an impurity, attempting to completely remove Na2O tends to increase the cost of the raw material batch and thus the manufacturing cost. To suppress the increase in manufacturing costs, the lower limit of the Na2O content is preferably 0.0003% or more, 0.0005% or more, and especially 0.001% or more.

[0058] K2O is a component that can be dissolved in Li2O-Al2O3-SiO2 crystals, significantly affecting crystallinity and reducing the viscosity of the glass, thereby improving its meltability and moldability. It is also a component used to adjust the thermal expansion coefficient and refractive index of crystallized glass. The K2O content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0-3%, 0-2.7%, 0-2.4%, 0-2.1%, 0-1.8%, 0-1.5%, 0-1.4%, 0-1.3%, 0-1.2%, 0-1.1%, 0-1%, 0-0.9%, and especially 0.1-0.8%. If the K2O content is too high, the crystallinity becomes too strong, making the glass prone to devitrification and the crystallized glass more susceptible to breakage. Furthermore, the ionic radius of the K cation is larger than that of the Li cation and Mg cation, which are components of the main crystal, and is therefore less likely to be incorporated into the crystal. As a result, the K cation tends to remain in the residual glass after crystallization. Therefore, if the K2O content is too high, a difference in refractive index between the crystalline phase and the residual glass is likely to occur, and the crystallized glass tends to become cloudy. However, since K2O is easily introduced as an impurity, attempting to completely remove K2O tends to increase the cost of the raw material batch and thus the manufacturing cost. To suppress the increase in manufacturing costs, it is preferable that the lower limit of the K2O content be 0.0003% or more, 0.0005% or more, and especially 0.001% or more.

[0059] Li2O, Na2O, and K2O are components that improve the meltability and moldability of glass, but if the content of these components is too high, the low-temperature viscosity will drop too low, and there is a risk that the glass will flow too much during crystallization. In addition, Li2O, Na2O, and K2O are components that can worsen the weather resistance, water resistance, and chemical resistance of the glass before crystallization. If the glass before crystallization is deteriorated by moisture, etc., there is a risk that the desired crystallization behavior and, consequently, the desired properties cannot be obtained. On the other hand, ZrO2 is a component that functions as a nucleating agent, preferentially crystallizing in the early stages of crystallization and having the effect of suppressing the flow of residual glass. In addition, ZrO2 efficiently fills the voids in the glass network mainly composed of an SiO2 backbone, and has the effect of inhibiting the diffusion of protons and various chemical components within the glass network, improving the weather resistance, water resistance, and chemical resistance of the glass before crystallization. In order to obtain crystallized glass with the desired shape and properties, the (Li2O+Na2O+K2O) / ZrO2 ratio should be suitably controlled. The mass ratio of (Li2O+Na2O+K2O) / ZrO2 is preferably 2.0 or less, 1.98 or less, 1.96 or less, 1.94 or less, 1.92 or less, and especially 1.90 or less.

[0060] CaO is a component that reduces the viscosity of glass, improving its meltability and moldability. It is also a component that adjusts the thermal expansion coefficient and refractive index of crystallized glass. The CaO content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0-3%, 0-2.7%, 0-2.4%, 0-2.1%, 0-1.8%, and especially preferably 0-1.5%. If the CaO content is too high, the glass becomes more prone to devitrification, and the crystallized glass becomes more fragile. In addition, the ionic radius of Ca cations is larger than that of Li cations and Mg cations, which are components of the main crystal, and they are not easily incorporated into the crystal, so Ca cations tend to remain in the residual glass after crystallization. For this reason, if the CaO content is too high, a difference in refractive index between the crystalline phase and the residual glass is more likely to occur, and the crystallized glass tends to become cloudy. However, since CaO is easily introduced as an impurity, attempting to completely remove CaO tends to increase the cost of raw material batches and thus the overall manufacturing cost. To suppress the increase in manufacturing costs, it is preferable that the lower limit of the CaO content be 0.0001% or higher, 0.0003% or higher, and especially 0.0005% or higher.

[0061] SrO is a component that reduces the viscosity of glass, improving its meltability and moldability. It is also a component that adjusts the thermal expansion coefficient and refractive index of crystallized glass. The SrO content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0-3%, 0-2.7%, 0-2.4%, 0-2.1%, 0-1.8%, 0-1.5%, and especially preferably 0-1%. If the SrO content is too high, the glass becomes more prone to devitrification, and the crystallized glass becomes more fragile. In addition, the ionic radius of Sr cations is larger than that of Li cations and Mg cations, which are components of the main crystal, and they are not easily incorporated into the crystal, so Sr cations tend to remain in the residual glass after crystallization. For this reason, if the SrO content is too high, a difference in refractive index between the crystalline phase and the residual glass is more likely to occur, and the crystallized glass tends to become cloudy. However, since SrO is easily introduced as an impurity, attempting to completely remove SrO tends to increase the cost of raw material batches and thus the overall manufacturing cost. To suppress the increase in manufacturing costs, it is preferable that the lower limit of the SrO content be 0.0001% or higher, 0.0003% or higher, and especially 0.0005% or higher.

[0062] BaO is a component that reduces the viscosity of glass, improving its meltability and moldability. It is also a component that adjusts the thermal expansion coefficient and refractive index of crystallized glass. The BaO content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0-3%, 0-2.7%, 0-2.4%, 0-2.1%, 0-1.8%, 0-1.5%, and especially preferably 0-1%. If the BaO content is too high, Ba-containing crystals will precipitate, making the glass more prone to devitrification and crystallized glass more susceptible to breakage. In addition, the ionic radius of Ba cations is larger than that of Li cations and Mg cations, which are components of the main crystal, and they are not easily incorporated into the crystal, so Ba cations tend to remain in the residual glass after crystallization. For this reason, if the BaO content is too high, a difference in refractive index between the crystalline phase and the residual glass is more likely to occur, and the crystallized glass tends to become cloudy. However, since BaO is easily introduced as an impurity, attempting to completely remove BaO tends to increase the cost of raw material batches and thus the overall manufacturing cost. To suppress the increase in manufacturing costs, it is preferable that the lower limit of the BaO content be 0.0001% or higher, 0.0003% or higher, and especially 0.0005% or higher.

[0063] MgO, CaO, SrO, and BaO are components that improve the meltability and moldability of glass, but if the content of these components is too high, the low-temperature viscosity will drop too low, and there is a risk that the glass will flow too much during crystallization. On the other hand, ZrO2 is a component that functions as a nucleating agent, and it preferentially crystallizes in the early stages of crystallization, suppressing the flow of residual glass. In order to obtain crystallized glass with the desired shape and properties, the (MgO+CaO+SrO+BaO) / ZrO2 ratio should be suitably controlled. The mass ratio of (MgO+CaO+SrO+BaO) / ZrO2 is preferably 0-3, 0-2.8, 0-2.6, 0-2.4, 0-2.2, 0-2.1, 0-2, 0-1.8, 0-1.7, 0-1.6, and especially 0-1.5.

[0064] Na2O, K2O, CaO, SrO, and BaO tend to remain in the residual glass after crystallization. Therefore, if the amount of these compounds is too high, a difference in refractive index between the crystalline phase and the residual glass is likely to occur, making the crystallized glass prone to clouding. For this reason, the amount of Na2O+K2O+CaO+SrO+BaO is preferably 8% or less, 7% or less, 6% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.7% or less, 2.42% or less, 2.415% or less, 2.410% or less, 2.405% or less, and especially 2.4% or less.

[0065] Li2O, Na2O, K2O, MgO, CaO, SrO, and BaO are components that improve the meltability and moldability of glass. Furthermore, glass melts containing large amounts of MgO, CaO, SrO, and BaO tend to have a gradual change in viscosity (viscosity curve) with respect to temperature, while glass melts containing large amounts of Li2O, Na2O, and K2O tend to have a rapid change. If the change in viscosity curve is too gradual, the glass will continue to flow even after being molded into a predetermined shape, making it difficult to obtain the desired shape. On the other hand, if the change in viscosity curve is too rapid, the glass melt will solidify during the molding process, making it difficult to obtain the desired shape. For this reason, the ratio (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) should be appropriately controlled. The mass ratio of (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) is preferably 0-2, 0-1.8, 0-1.5, 0-1.2, 0-1, 0-0.9, 0-0.8, 0-0.7, 0-0.6, 0-0.5, and particularly preferably 0-0.45.

[0066] ZnO dissolves in Li2O-Al2O3-SiO2-based crystals and is a component that significantly affects crystallinity. It is also a component for adjusting the thermal expansion coefficient and refractive index of the crystallized glass. The content of ZnO is preferably 0 to 10%, 0 to 8%, 0 to 6%, 0 to 5%, 0 to 4.5%, 0 to 4%, 0 to 3.5%, 0 to 3%, 0 to 2.7%, 0 to 2.4%, 0 to 2.1%, 0 to 1.8%, 0 to 1.5%, particularly 0 to 1%. If the content of ZnO is too high, the crystallinity becomes too strong and devitrification is likely to occur, making the glass prone to breakage. However, since ZnO is easily mixed as an impurity, if an attempt is made to completely remove ZnO, the raw material batch becomes expensive and the manufacturing cost tends to increase. In order to suppress the increase in manufacturing cost, the lower limit of the content of ZnO is preferably 0.0001% or more, 0.0003% or more, particularly 0.0005% or more.

[0067] In Li2O-Al2O3-SiO2-based crystallized glass, Li cations, Mg cations, and Zn cations are components that easily dissolve in the β-quartz solid solution, and these cations dissolve in the crystal in a form that compensates for the charge of Al cations. Specifically, Si 4+ ⇔ Al 3+ + (Li + , 1 / 2×Mg 2+ , 1 / 2×Zn 2+ ) is considered to be dissolved in such a form, and the ratio of Al cations to Li cations, Mg cations, and Zn cations affects the stability of the β-quartz solid solution. In the composition described in the present application, in order to stably obtain crystallized glass and make this crystallized glass colorless, transparent and approach zero expansion, Al2O3 / (Li2O+(1 / 2×(MgO+ZnO)) is preferably 3.0 to 8.0, 3.2 to 7.8, 3.4 to 7.6, 3.5 to 7.5, 3.7 to 7.5, 4.0 to 7.5, 4.3 to 7.5, 4.5 to 7.5, 4.8 to 7.5, 5.0 to 7.5, 5.5 to 7.3, 5.5 to 7.1, 5.5 to 7.0, 5.5 to 6.8, 5.5 to 6.7, 5.5 to 6.6, particularly 5.5 to 6.5 in terms of mass ratio.

[0068] Y2O3 is a component that reduces the viscosity of glass, improving its meltability and moldability. It is also a component that improves the Young's modulus of crystallized glass, adjusting the coefficient of thermal expansion and refractive index. The Y2O3 content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0-3%, 0-2.7%, 0-2.4%, 0-2.1%, 0-1.8%, 0-1.5%, and especially preferably 0-1%. If the Y2O3 content is too high, crystals containing Y will precipitate, making the glass more prone to devitrification and crystallized glass more susceptible to breakage. Furthermore, the ionic radius of the Y cation is larger than that of the main crystal components such as Li cations and Mg cations, making it difficult to incorporate into the crystal, so the Y cation tends to remain in the residual glass after crystallization. Therefore, if the Y2O3 content is too high, a difference in refractive index between the crystalline phase and the residual glass is more likely to occur, and the crystallized glass tends to become cloudy. However, since Y2O3 can be present as an impurity, attempting to completely remove it tends to increase the cost of the raw material batch and thus the manufacturing cost. To suppress the increase in manufacturing costs, it is preferable that the lower limit of the Y2O3 content be 0.0001% or higher, 0.0003% or higher, and especially 0.0005% or higher.

[0069] In Li2O-Al2O3-SiO2 crystallized glass, Li cations, Mg cations, and Zn cations are readily soluble in β-quartz solid solutions and are considered to contribute less to the increase in refractive index of the residual glass after crystallization compared to Ba cations, etc. Furthermore, Li2O, MgO, and ZnO function as fluxes during the vitrification of the raw materials, making them important components for producing colorless, transparent crystallized glass at low temperatures. Li2O is an essential component for achieving low expansion and must be included at a concentration of 1% or more. While the required amount of Li2O must be included to achieve the desired thermal expansion coefficient, increasing the content of MgO and ZnO in conjunction with it may lead to an excessive decrease in the viscosity of the glass. If the low-temperature viscosity is too low, the glass may become too soft and fluid during firing, making it difficult to crystallize into the desired shape. Conversely, if the high-temperature viscosity is too low, although the thermal load on the manufacturing equipment decreases, the convection velocity during heating increases, potentially leading to increased physical corrosion of refractories and other materials. Therefore, it is preferable to control the content ratio of Li2O, MgO, and ZnO, and in particular, it is preferable to control the combined amount of MgO and ZnO relative to Li2O, which has high flux function. Therefore, it is preferable to make the mass ratio of (MgO + ZnO) / Li2O small, such as 0.394 or less, 0.393 or less, 0.392 or less, 0.391 or less, and especially 0.390 or less, or large, such as 0.755 or more, 0.756 or more, 0.757 or more, 0.758 or more, and especially 0.759 or more.

[0070] B2O3 is a component that reduces the viscosity of glass, improving its meltability and moldability. It is also a component that may be involved in the ease with which phase separation occurs during crystal nucleation. The B2O3 content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0-3%, 0-2.7%, 0-2.4%, 0-2.1%, 0-1.8%, and especially 0-1.5%. If the B2O3 content is too high, the amount of B2O3 evaporated during melting increases, leading to a higher environmental burden. However, since B2O3 is easily mixed in as an impurity, attempting to completely remove B2O3 tends to increase the cost of raw material batches and thus increase manufacturing costs. To suppress the increase in manufacturing costs, the B2O3 content may be 0.0001% or more, 0.0003% or more, and especially 0.0005% or more.

[0071] In Li2O-Al2O3-SiO2 crystallized glass, it is known that a phase separation region is formed within the glass before crystal nucleation, and then crystal nuclei composed of TiO2, ZrO2, etc. are formed within that phase separation region. Since SnO2, ZrO2, P2O5, TiO2, and B2O3 are strongly involved in phase separation, the proportions of SnO2+ZrO2+P2O5+TiO2+B2O3 are 1.5~30%, 1.5~26%, 1.5~22%, 1.5~20%, 1.5~18%, 1.5~16%, 1.5~15%, 1.8~15%, 2.1~15%, 2.4~15%, 2.5~15%, 2.8~15%, 2.8~13%, 2.8~12%, 2.8~11%, and 2.8~10%. The amounts of P2O5+B2O3+SnO2+TiO2+ZrO2 are preferably 3-9.5%, 3-9.2%, and particularly preferably 3-9%, and the mass ratio of SnO2 / (SnO2+ZrO2+P2O5+TiO2+B2O3) is preferably 0.06 or higher, 0.07 or higher, 0.08 or higher, 0.09 or higher, 0.1 or higher, 0.103 or higher, 0.106 or higher, 0.11 or higher, 0.112 or higher, 0.115 or higher, 0.118 or higher, 0.121 or higher, 0.124 or higher, 0.127 or higher, 0.128 or higher, and particularly preferably 0.13 or higher. If the amount of P2O5+B2O3+SnO2+TiO2+ZrO2 is too low, it becomes difficult to form a phase separation region and crystallization becomes difficult. On the other hand, if there is too much P2O5 + B2O3 + SnO2 + TiO2 + ZrO2 and / or if SnO2 / (SnO2 + ZrO2 + P2O5 + TiO2 + B2O3) is too small, the phase separation region becomes larger, and the crystallized glass is more likely to become cloudy. There is no particular upper limit to SnO2 / (SnO2 + ZrO2 + P2O5 + TiO2 + B2O3), but in reality it is 0.9 or less.

[0072] Fe2O3 is a component that enhances the coloration of glass, and in particular, it significantly enhances coloration through interaction with TiO2 and SnO2. The Fe2O3 content is preferably 0.10% or less, 0.08% or less, 0.06% or less, 0.05% or less, 0.04% or less, 0.035% or less, 0.03% or less, 0.02% or less, 0.015% or less, 0.013% or less, 0.012% or less, 0.011% or less, 0.01% or less, 0.009% or less, 0.008% or less, 0.007% or less, 0.006% or less, 0.005% or less, 0.004% or less, 0.003% or less, and especially preferably 0.002% or less. However, since Fe2O3 is easily mixed in as an impurity, attempting to completely remove Fe2O3 tends to increase the cost of raw material batches and thus increase manufacturing costs. To suppress increases in manufacturing costs, the lower limit of the Fe2O3 content is preferably 0.0001% or higher, 0.0002% or higher, 0.0003% or higher, 0.0005% or higher, and especially 0.001% or higher.

[0073] When titanium and iron coexist, ilmenite (FeTiO3)-like discoloration may occur. In particular, in Li2O-Al2O3-SiO2 crystallized glass, titanium and iron components that did not precipitate as crystal nuclei or main crystals after crystallization remain in the residual glass, which can promote the appearance of the above discoloration. In compositional design, it is possible to reduce the amount of these components, but since TiO2 and Fe2O3 are easily mixed in as impurities, attempting to completely remove them tends to increase the cost of raw material batches and thus the manufacturing cost. For this reason, in order to suppress manufacturing costs, it is acceptable to include TiO2 and Fe2O3 within the range mentioned above, and in order to further reduce manufacturing costs, it is acceptable to include both components within a range where discoloration is tolerable. In such cases, the mass ratio of TiO2 / (TiO2+Fe2O3) is preferably 0.001~0.999, 0.003~0.997, 0.005~0.995, 0.007~0.993, 0.009~0.991, 0.01~0.99, 0.1~0.9, 0.15~0.85, 0.2~0.8, 0.25~0.25, 0.3~0.7, 0.35~0.65, and particularly preferably 0.4~0.6. This makes it easier to obtain colorless, highly transparent crystallized glass at a low cost.

[0074] Platinum (Pt) is a component that can be mixed into glass in the form of ions, colloids, or metals, causing yellow to brownish discoloration. This tendency becomes more pronounced after crystallization. Furthermore, intensive investigation has revealed that the presence of Pt can affect the nucleation and crystallization behavior of crystallized glass, potentially leading to cloudiness. For this reason, the Pt content is preferably 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1.6 ppm or less, 1.4 ppm or less, 1.2 ppm or less, 1 ppm or less, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.45 ppm or less, 0.40 ppm or less, 0.35 ppm or less, and especially 0.30 ppm or less. While Pt should be avoided as much as possible, the use of Pt components may be necessary to obtain homogeneous glass when using general melting equipment. Therefore, attempting to completely remove Pt tends to increase manufacturing costs. When it does not adversely affect the coloring, in order to suppress the increase in manufacturing costs, the lower limit of the Pt content is preferably 0.0001 ppm or more, 0.001 ppm or more, 0.005 ppm or more, 0.01 ppm or more, 0.02 ppm or more, 0.03 ppm or more, 0.04 ppm or more, 0.05 ppm or more, 0.06 ppm or more, and especially 0.07 ppm or more. Furthermore, when coloring is acceptable, Pt may be used as a nucleating agent to promote the precipitation of the main crystal, similar to ZrO2 or TiO2. In this case, Pt may be used as a nucleating agent alone, or in combination with other components. Also, when Pt is used as a nucleating agent, its form is not particularly restricted (colloid, metallic crystal, etc.).

[0075] Rh is a component that can be mixed into glass in the form of ions, colloids, or metals, and like Pt, it tends to cause yellow to brownish discoloration and cloudiness of crystallized glass. For this reason, it is preferable that the Rh content be 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1.6 ppm or less, 1.4 ppm or less, 1.2 ppm or less, 1 ppm or less, 0.9 ppm or less, 0.8 ppm or less, 0.7 ppm or less, 0.6 ppm or less, 0.5 ppm or less, 0.45 ppm or less, 0.40 ppm or less, 0.35 ppm or less, and especially 0.30 ppm or less. Although the inclusion of Rh should be avoided as much as possible, when using general melting equipment, it may be necessary to use Rh components to obtain homogeneous glass. For this reason, attempting to completely remove Rh tends to increase manufacturing costs. When it does not adversely affect the coloring, in order to suppress increases in manufacturing costs, the lower limit of the Rh content is preferably 0.0001 ppm or more, 0.001 ppm or more, 0.005 ppm or more, 0.01 ppm or more, 0.02 ppm or more, 0.03 ppm or more, 0.04 ppm or more, 0.05 ppm or more, 0.06 ppm or more, and especially 0.07 ppm or more. Furthermore, when coloring is acceptable, Rh may be used as a nucleating agent in the same way as ZrO2 and TiO2. In this case, Rh may be used as a nucleating agent alone or in combination with other components. Also, when Rh is used as a nucleating agent to promote the precipitation of the main crystal, the form is not particularly limited (colloid, metallic crystal, etc.).

[0076] Furthermore, Pt+Rh levels were below 9 ppm, below 8 ppm, below 7 ppm, below 6 ppm, below 5 ppm, below 4.75 ppm, below 4.5 ppm, below 4.25 ppm, below 4 ppm, below 3.75 ppm, below 3.5 ppm, below 3.25 ppm, below 3 ppm, below 2.75 ppm, below 2.5 ppm, below 2.25 ppm, below 2 ppm, below 1.75 ppm, and below 1.5 ppm. The following are preferable: 1.25 ppm or less, 1 ppm or less, 0.95 ppm or less, 0.9 ppm or less, 0.85 ppm or less, 0.8 ppm or less, 0.75 ppm or less, 0.7 ppm or less, 0.65 ppm or less, 0.60 ppm or less, 0.55 ppm or less, 0.50 ppm or less, 0.45 ppm or less, 0.40 ppm or less, 0.35 ppm or less, and especially 0.30 ppm or less. Although the inclusion of Pt and Rh should be avoided as much as possible, when using general melting equipment, the use of Pt and Rh components may be necessary to obtain homogeneous glass. Therefore, attempting to completely remove Pt and Rh tends to increase manufacturing costs. In cases where it does not adversely affect coloring, in order to suppress increases in manufacturing costs, the lower limit of Pt+Rh is preferably 0.0001 ppm or higher, 0.001 ppm or higher, 0.005 ppm or higher, 0.01 ppm or higher, 0.02 ppm or higher, 0.03 ppm or higher, 0.04 ppm or higher, 0.05 ppm or higher, 0.06 ppm or higher, and especially 0.07 ppm or higher.

[0077] In developing glass materials, it is common practice to produce glass of various compositions using various crucibles. As a result, platinum and rhodium evaporated from the crucible are often present inside the electric furnace used for melting. It has been confirmed that Pt and Rh present inside the electric furnace are mixed into the glass. To control the amount of Pt and Rh mixed in, it is possible to control the Pt and Rh content in the glass by selecting the raw materials and crucible materials used, as well as by attaching a quartz lid to the crucible, and by lowering the melting temperature and shortening the melting time.

[0078] MoO3 is a component that can be introduced from raw materials or melting components, and it is a component that promotes crystallization. The MoO3 content is preferably 0-10%, 0-8%, 0-6%, 0-5%, 0-4.5%, 0-4%, 0-3.5%, 0-3%, 0-2.7%, 0-2.4%, 0-2.1%, 0-1.8%, 0-1.5%, 0-1%, 0-0.5%, 0-0.1%, 0-0.05%, and especially preferably 0-0.005%. If the MoO3 content is too high, crystals containing Mo will precipitate, making the glass more prone to devitrification and the crystallized glass more likely to break. In addition, the ionic radius of Mo cations is larger than that of Li cations and Mg cations, which are components of the main crystal, and they are not easily incorporated into the crystal, so Mo cations tend to remain in the residual glass after crystallization. Therefore, if the MoO3 content is too high, a difference in refractive index between the crystalline phase and the residual glass is more likely to occur, and the crystallized glass tends to become cloudy. Furthermore, if the MoO3 content is too high, there is a risk of yellow discoloration. However, since MoO3 can be present as an impurity, attempting to completely remove MoO3 tends to increase the cost of the raw material batch and thus the manufacturing cost. To suppress the increase in manufacturing costs, it is preferable that the lower limit of the MoO3 content is greater than 0%, 0.0001% or more, 0.0003% or more, and especially 0.0005% or more.

[0079] As2O3 and Sb2O3 are highly toxic and can contaminate the environment during glass manufacturing processes and waste glass disposal. Therefore, it is preferable that Sb2O3 + As2O3 be present in amounts of 2% or less, 1% or less, 0.7% or less, less than 0.7%, 0.65% or less, 0.6% or less, 0.55% or less, 0.5% or less, 0.45% or less, 0.4% or less, 0.35% or less, 0.3% or less, 0.25% or less, 0.2% or less, 0.15% or less, 0.1% or less, 0.05% or less, or even substantially absent (specifically, less than 0.01% by mass). If As2O3 or Sb2O3 are included, these components may function as clarifying agents or nucleating agents.

[0080] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention may contain trace components such as H2, CO2, CO, H2O, He, Ne, Ar, and N2, up to 0.1% each, in addition to the above components, as long as they do not adversely affect the coloration. Furthermore, intentionally adding components such as Ag, Au, Pd, Ir, V, Cr, Sc, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ac, Th, Pa, and U to the glass tends to increase raw material costs and thus manufacturing costs. On the other hand, when glass containing Ag or Au is subjected to light irradiation or heat treatment, aggregates of these components are formed, which can then be used to promote crystallization. In addition, Pd and other components have various catalytic properties, and by including them, it is possible to impart unique functions to the glass or crystallized glass. In light of these circumstances, when the purpose is to promote crystallization or impart other functions, the above components may be contained in amounts of 1% or less, 0.5% or less, 0.3% or less, and 0.1% or less, respectively. If not, it is preferable that the amounts be 500 ppm or less, 300 ppm or less, 100 ppm or less, and especially 10 ppm or less.

[0081] Furthermore, as long as it does not adversely affect the coloring, the Li2O-Al2O3-SiO2-based crystallized glass of the present invention may contain up to 10% in total amount of SO3, MnO, Cl2, La2O3, WO3, HfO2, Ta2O5, Nd2O3, Nb2O5, RfO2, etc. However, since the raw material batches of the above components are expensive and tend to increase manufacturing costs, they do not need to be added unless there are special circumstances. In particular, since HfO2 has high raw material costs and Ta2O5 can be a conflict mineral, the combined amount 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 especially 0.045% or less.

[0082] In other words, the preferred composition range for implementing the Li2O-Al2O3-SiO2 crystallized glass of the present invention is SiO2 50-75%, Al2O3 10-30%, Li2O 1-8%, SnO2 0-5%, ZrO2 1-5%, MgO 0-10%, P2O 50-5%, TiO2 0-1.5%, (Li2O+Na2O+K2O) / ZrO2 0-1.5%, TiO2 / (TiO2+Fe2O3) 0.01-0.99, (MgO+ZnO) / Li2O 0-0.8%, and a β-OH value of 0.001-2 / mm, preferably SiO2 50-75%, Al2O3 10-30%, Li2O 1-8%, SnO2 0-5%, ZrO2 1-5%, MgO 0-10%, P2O 50-5%, TiO2 less than 1.5%, (Li2O+Na2O+K2O) / ZrO2 0-1.5%, TiO2 / (TiO2+Fe2O3) 0.01-0.99, (MgO+ZnO) / Li2O 0-0.8, (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) 0-0.5, β-OH value 0.001-2 / mm, more preferably SiO2 50-75%, Al2O3 10-30%, Li2O 1-8%, SnO2 greater than 5%, ZrO2 1-5%, MgO 0-10%, P2O 50-5%, TiO2 less than 1.5%, (Li2O+Na2O+K2O) / ZrO2 0-1.5%, TiO2 / (TiO2+Fe2O3) 0.01-0.99, (MgO+ZnO) / Li2O 0-0.8, (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) 0-0.5, (MgO+CaO+SrO+BaO) / ZrO2 0-2, β-OH value 0.001-2 / mm, more preferably SiO2 50-75%, Al2O3 10-30%, Li2O 1-8%, SnO20 greater than 5%, ZrO2 1-5%, MgO 0~10%, P2O50~5%, TiO20~less than 1.5%, (Li2O+Na2O+K2O) / ZrO20~1.5, TiO2 / (TiO2+Fe2O3) 0.01~0.99, (MgO+ZnO) / Li2O 0~0.8, (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) 0~0.5, (MgO+CaO+SrO+BaO) / ZrO20~2, SnO2 / (SnO2+ZrO2+P2O5+TiO2+B2O3) 0.06~0.9, β-OH value is 0.The ratio is 0.01~2 / mm, and more preferably, SiO2 50~75%, Al2O3 10~30%, Li2O 1~8%, SnO20 greater than ~5%, ZrO2 1~5%, MgO 0~10%, P2O 50~5%, TiO20 less than 1.5%, (Li2O+Na2O+K2O) / ZrO20 ~1.5%, TiO2 / (TiO2+Fe2O3) 0.01~0.99%, (MgO+ZnO) / Li2O 0~0.8%, (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) 0~0.5, (MgO+CaO+SrO+BaO) / ZrO20~2, SnO2 / (SnO2+ZrO2+P2O5+TiO2+B2O3) 0.06~0.9, Pt+Rh 0~5ppm, β-OH value 0.001~2 / mm, more preferably SiO2 50~75%, Al2O3 10~30%, Li2O 1~8%, SnO20 greater than~5%, ZrO2 1~5%, MgO 0~10%, P2O 50~5%, TiO20 less than 1.5%, (Li2O+Na2O+K2O) / ZrO20~1.5, TiO2 / (TiO2+Fe2O3) 0.01~0.99, (MgO+ZnO) / Li2O 0~0.394, (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) 0~0.5, (MgO+CaO+SrO+BaO) / ZrO20~2, SnO2 / (SnO2+ZrO2+P2O5+TiO2+B2O3) 0.06~0.9, Pt+Rh 0~5ppm, β-OH value 0.001~2 / mm, more preferably SiO2 50~75%, Al2O3 10~30%, Li2O 1~8%, SnO20 over~5%, ZrO2 1~5%, MgO 0~10%, P2O50~5%, TiO20~less than 1.5%, (Li2O+Na2O+K2O) / ZrO20~1.5, TiO2 / (TiO2+Fe2O3) 0.01~0.99, (MgO+ZnO) / Li2O 0~0.394, (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) 0~0.5, (MgO+CaO+SrO+BaO) / ZrO20~2, SnO2 / (SnO2+ZrO2+P2O5+TiO2+B2O3) 0.06~0.9, Pt+Rh 0-5 ppm, HfO2 + Ta2O50-0.05%, β-OH value 0.001-2 / mm, Sb2O3 + As2O30.Less than 7%, particularly preferably SiO2 50-75%, Al2O3 10-30%, Li2O 1-8%, SnO20 greater than 5%, ZrO2 1-5%, MgO 0-10%, P2O 50-5%, TiO20 less than 1.5%, (Li2O+Na2O+K2O) / ZrO20 ~1.5%, TiO2 / (TiO2+Fe2O3) 0.01-0.99%, (MgO+ZnO) / Li2O 0-0.394%, (MgO+CaO+SrO+BaO) / (Li2O+Na2O+K2O) 0-0.5%, (MgO+CaO+SrO+BaO) / ZrO20 ~2%, SnO2 / (SnO2+ZrO2+P2O5+TiO2+B2O3) The values ​​are 0.06-0.9, Pt+Rh 0-5 ppm, HfO2+Ta2O 50-0.05%, β-OH value 0.001-2 / mm, Sb2O3+As2O3 less than 0.7%, and Al2O3 / (Li2O+(1 / 2×(MgO+ZnO))) 5.0-7.5.

[0083] The Li2O-Al2O3-SiO2 crystallized glass of the present invention having the above composition tends to be colorless and transparent in appearance.

[0084] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention has a β-OH value of 0.001~2 / mm, and is available in the following ranges: 0.01~1.5 / mm, 0.02~1.5 / mm, 0.03~1.2 / mm, 0.04~1.5 / mm, 0.05~1 / mm, 0.06~1 / mm, 0.07~1 / mm, 0.08~0.9 / mm, and 0.08~0.85 / mm. Preferably, the β-OH value is 0.08~0.8 / mm, 0.08~0.75 / mm, 0.08~0.7 / mm, 0.08~0.65 / mm, 0.08~0.6 / mm, 0.08~0.55 / mm, 0.08~0.54 / mm, 0.08~0.53 / mm, 0.08~0.52 / mm, 0.08~0.51 / mm, and especially preferably 0.08~0.5 / mm. If the β-OH value is too small, the rate of crystal nucleation in the crystallization process slows down, and the amount of crystal nuclei produced tends to decrease. As a result, there are many coarse crystals, the crystallized glass becomes cloudy, and its transparency is easily impaired. The reason why crystallization progresses when the β-OH value is large is not fully understood, but it is thought that one reason is that the β-OH group weakens the bonds of the glass skeleton and reduces the viscosity of the glass. Furthermore, it is thought that the presence of β-OH groups in the glass makes it easier for components that can function as crystal nuclei, such as Zr, to move, which is one of the contributing factors. On the other hand, if the β-OH value is too high, bubbles are more likely to form at the interface between the glass and metal glass manufacturing furnace components containing Pt or other materials, or glass manufacturing furnace components made of refractory materials, which can easily degrade the quality of the glass product. In addition, β-quartz solid solution crystals are more likely to transform into β-spodumene solid solution crystals, which can lead to larger crystal grain sizes, and a difference in refractive index is more likely to occur within the crystallized glass, resulting in the crystallized glass becoming cloudy. Note that the β-OH value changes depending on the raw materials used, the melting atmosphere, the melting temperature, the melting time, etc., and the β-OH value can be adjusted by changing these conditions as needed.

[0085] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a transmittance of 0% or more, 2.5% or more, 5% or more, 10% or more, 12% or more, 14% or more, 16% or more, 18% or more, 20% or more, 22% or more, 24% or more, 26% or more, 28% or more, 30% or more, 32% or more, 34% or more, 36% or more, 38% or more, 40% or more, 40.5% or more, 41% or more, 41.5% or more, 42% or more, 42.5% or more, 43% or more, 43.5% or more, 44% or more, 44.5% or more, and is particularly preferably 45% or more, when the glass has a thickness of 3 mm and a transmittance of 5% or more at a wavelength of 200 nm. In applications where ultraviolet light transmission is required, if the transmittance at a wavelength of 200 nm is too low, the desired transmittance may not be achieved. In particular, when used in photocleaning with ozone lamps, medical applications using excimer lasers, or exposure applications, a higher transmittance at a wavelength of 200 nm is preferable.

[0086] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a thickness of 3 mm and a transmittance at a wavelength of 250 nm of 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, and is particularly preferably 16% or higher. In applications where ultraviolet light transmission is required, if the transmittance at a wavelength of 250 nm is too low, the desired transmittance may not be achieved. In particular, when used in sterilization applications using low-pressure mercury lamps or processing applications using YAG lasers, a higher transmittance at a wavelength of 250 nm is preferable.

[0087] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a transmittance of 0% or more, 2.5% or more, 5% or more, 10% or more, 12% or more, 14% or more, 16% or more, 18% or more, 20% or more, 22% or more, 24% or more, 26% or more, 28% or more, 30% or more, 32% or more, 34% or more, 36% or more, 38% or more, 40% or more, 40.5% or more, 41% or more, 41.5% or more, 42% or more, 42.5% or more, 43% or more, 43.5% or more, 44% or more, 44.5% or more, and is particularly preferably 45% or more, when used in applications such as UV curing, adhesion, drying, fluorescence detection of printed materials, and insect attraction.

[0088] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a transmittance of 0% or more, 2.5% or more, 5% or more, 10% or more, 12% or more, 14% or more, 16% or more, 18% or more, 20% or more, 22% or more, 24% or more, 26% or more, 28% or more, 30% or more, 32% or more, 34% or more, 36% or more, 38% or more, 40% or more, 42% or more, 44% or more, 46% or more, 48% or more, 50% or more, 52% or more, 54% or more, 56% or more, 57% or more, 58% or more, 59% or more, 60% or more, 61% or more, 62% or more, 63% or more, 64% or more, and is particularly 65% ​​or more, at a thickness of 3 mm and a wavelength of 325 nm. In particular, when used for UV curing, bonding, and drying, fluorescence detection of printed materials, and insect attraction applications, a higher transmittance at a wavelength of 325 nm is preferable.

[0089] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a transmittance of 0% or more, 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 80% or more, 81% or more, 82% or more, 83% or more, and is particularly preferably 84% or more. When used in processing using a YAG laser or the like, a higher transmittance at a wavelength of 350 nm is preferable.

[0090] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a thickness of 3 mm and a transmittance at a wavelength of 380 nm of 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 78% or more, 80% or more, 81% or more, 82% or more, 83% or more, and particularly 84% or more. If the transmittance at a wavelength of 380 nm is too low, the yellow coloration will become stronger, and the transparency of the crystallized glass will decrease, which may prevent the desired transmittance from being obtained.

[0091] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a thickness of 3 mm and a transmittance at a wavelength of 800 nm of 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 78% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, and particularly 88% or more. If the transmittance at a wavelength of 800 nm is too low, it tends to turn green. In particular, when used in medical applications such as vein authentication, a higher transmittance at a wavelength of 800 nm is preferable.

[0092] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a thickness of 3 mm and a transmittance at a wavelength of 1200 nm of 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 72% or more, 74% or more, 76% or more, 78% or more, 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, and especially 89% or more. If the transmittance at a wavelength of 1200 nm is too low, it tends to turn green. In particular, when used in infrared communication applications such as infrared cameras and remote controls, a higher transmittance at a wavelength of 1200 nm is preferable.

[0093] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a transmittance change rate before and after crystallization of 50% or less, 48% or less, 46% or less, 44% or less, 42% or less, 40% or less, 38% or less, 37.5% or less, 37% or less, 36.5% or less, 36% or less, 35.5% or less, and particularly 35% or less at a thickness of 3 mm and a wavelength of 300 nm. By reducing the transmittance change rate before and after crystallization, it becomes possible to predict and control the transmittance after crystallization before crystallization occurs, making it easier to obtain the desired transmittance after crystallization. It is preferable that the transmittance change rate before and after crystallization is small not only at a wavelength of 300 nm but also across the entire wavelength range.

[0094] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a lightness L* of 50 or more, 60 or more, 65 or more, 70% or more, 75 or more, 80 or more, 85 or more, 90 or more, 91 or more, 92 or more, 93 or more, 94 or more, 95 or more, 96 or more, 96.1 or more, 96.3 or more, and especially 96.5 or more at a thickness of 3 mm. If the lightness L* is too low, it tends to appear grayish and dark regardless of the chromaticity.

[0095] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a chromaticity a* of ±5.0, ±4.5, ±4, ±3.6, ±3.2, ±2.8, ±2.4, ±2, ±1.8, ±1.6, ±1.4, ±1.2, ±1, ±0.9, ±0.8, ±0.7, ±0.6, and is particularly preferably within ±0.5 at a thickness of 3 mm. If the brightness 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.

[0096] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a chromaticity b* of ±5.0, ±4.5, ±4, ±3.6, ±3.2, ±2.8, ±2.4, ±2, ±1.8, ±1.6, ±1.4, ±1.2, ±1, ±0.9, ±0.8, ±0.7, ±0.6, and is particularly preferably within ±0.5 at a thickness of 3 mm. If the lightness b* is too large in the negative direction, it tends to appear blue, and if it is too large in the positive direction, it tends to appear yellow.

[0097] The Li2O-Al2O3-SiO2 crystallized glass of the present invention has a strain point (glass viscosity is approximately 10) in the glass state before crystallization. 14.5 The temperature corresponding to dPa·s is preferably 600°C or higher, 605°C or higher, 610°C or higher, 615°C or higher, 620°C or higher, 630°C or higher, 635°C or higher, 640°C or higher, 645°C or higher, 650°C or higher, and especially 655°C or higher. If the strain point is too low, the glass will be prone to cracking when it is molded before crystallization.

[0098] The Li2O-Al2O3-SiO2 crystallized glass of the present invention has an annealing point (glass viscosity is approximately 10%) in the glass state before crystallization. 13 The temperature corresponding to dPa·s is preferably 680°C or higher, 685°C or higher, 690°C or higher, 695°C or higher, 700°C or higher, 705°C or higher, 710°C or higher, 715°C or higher, 720°C or higher, and especially 725°C or higher. If the annealing point is too low, the glass will be prone to cracking when molded before crystallization.

[0099] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention readily crystallizes upon heat treatment, and therefore, unlike common glasses such as soda-lime glass, its softening point (glass viscosity is approximately 10%) is lower. 7.6 It is not easy to measure the temperature (corresponding to dPa·s). Therefore, in the Li2O-Al2O3-SiO2 crystallized glass of the present invention, the temperature at which the slope of the thermal expansion curve of the glass before crystallization changes is defined as the glass transition temperature and treated as a substitute for the softening point. In the Li2O-Al2O3-SiO2 crystallized glass of the present invention, it is preferable that the glass transition temperature in the glass state before crystallization is 680°C or higher, 685°C or higher, 690°C or higher, 695°C or higher, 700°C or higher, 705°C or higher, 710°C or higher, 715°C or higher, 720°C or higher, and particularly 725°C or higher. If the glass transition temperature is too low, the glass will flow too much during crystallization, making it difficult to mold it into the desired shape.

[0100] The Li2O-Al2O3-SiO2 crystallized glass of the present invention preferably has a liquidus temperature of 1540°C or lower, 1535°C or lower, 1530°C or lower, 1525°C or lower, 1520°C or lower, 1515°C or lower, 1510°C or lower, 1505°C or lower, 1500°C or lower, 1495°C or lower, 1490°C or lower, 1485°C or lower, 1480°C or lower, 1475°C or lower, 1470°C or lower, 1465°C or lower, 1460°C or lower, 1455°C or lower, 1450°C or lower, 1445°C or lower, 1440°C or lower, 1435°C or lower, 1430°C or lower, 1425°C or lower, 1420°C or lower, 1415°C or lower, and particularly 1410°C or lower. If the liquidus temperature is too high, devitrification is likely to occur during manufacturing. On the other hand, if the temperature is below 1480°C, manufacturing becomes easier using methods such as the roll method; if it is below 1450°C, manufacturing becomes easier using methods such as the casting method; and if it is below 1410°C, manufacturing becomes easier using methods such as the fusion method.

[0101] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a liquid-phase viscosity (logarithm of viscosity corresponding to liquid-phase temperature) of 2.70 or higher, 2.75 or higher, 2.80 or higher, 2.85 or higher, 2.90 or higher, 2.95 or higher, 3.00 or higher, 3.05 or higher, 3.10 or higher, 3.15 or higher, 3.20 or higher, 3.25 or higher, 3.30 or higher, 3.35 or higher, 3.40 or higher, 3.45 or higher, 3.50 or higher, 3.55 or higher, 3.60 or higher, 3.65 or higher, and is particularly preferably 3.70 or higher. If the liquid-phase viscosity is too low, devitrification is likely to occur during manufacturing. On the other hand, if it is 3.40 or higher, manufacturing by the roll method becomes easier; if it is 3.50 or higher, manufacturing by the slip casting method becomes easier; and if it is 3.70 or higher, manufacturing by the fusion method becomes easier.

[0102] In the Li2O-Al2O3-SiO2-based crystallized glass of the present invention, it is preferable that a β-quartz solid solution precipitates as the main crystal. Precipitating a β-quartz solid solution as the main crystal tends to result in smaller crystal grain sizes, making the crystallized glass more transparent and allowing for easier transmission of visible light. Furthermore, it becomes easier to bring the thermal expansion coefficient of the glass close to zero. In the Li2O-Al2O3-SiO2-based crystallized glass of the present invention, β-spodumene solid solution precipitates by heat treatment at a higher temperature than the crystallization conditions for β-quartz solid solution precipitation. The crystal grain size of the β-spodumene solid solution tends to be larger than that of the β-quartz solid solution, and generally, crystallized glass tends to become cloudy. However, by suitably adjusting the glass composition and firing conditions, the refractive index difference between the crystalline phase containing the β-spodumene solid solution and the remaining glass phase can be reduced, in which case the crystallized glass becomes less prone to clouding. In the Li2O-Al2O3-SiO2-based crystallized glass of the present invention, crystals such as β-spodumene solid solution may be included, as long as they do not adversely affect the coloring or other properties.

[0103] The Li2O-Al2O3-SiO2 crystallized glass of the present invention has a thermal expansion coefficient of 30 × 10 at 30 to 380°C. -7 / ℃ or below, 25×10 -7 / ℃ or below, 20×10 -7 / ℃ or below, 18×10 -7 / ℃ or below, 16×10-7 / ℃ or below, 14×10 -7 / ℃ or below, 13×10 -7 / ℃ or below, 12×10 -7 / ℃ or below, 11×10 -7 Below / ℃, 10×10 -7 / ℃ or below, 9×10 -7 / ℃ or below, 8×10 -7 / ℃ or below, 7×10 -7 / ℃ or below, 6×10 -7 / ℃ or below, 5×10 -7 / ℃ or below, 4×10 -7 Below / ℃, 3×10 -7 / ℃ or lower, especially 2 × 10 -7 It is preferable that the temperature be below / ℃. However, if dimensional stability and / or thermal shock resistance are particularly required, -5 × 10 -7 / ℃~5×10 -7 / ℃, -3×10 -7 / ℃~3×10 -7 / ℃, -2.5 × 10 -7 / ℃~2.5×10 -7 / ℃, -2 × 10 -7 / ℃~2×10 -7 / ℃, -1.5×10 -7 / ℃~1.5×10 -7 / ℃, -1 × 10 -7 / ℃~1×10 -7 / ℃, especially -0.5 × 10 -7 / ℃~0.5×10 -7 It is preferable that the temperature is / ℃.

[0104] The Li2O-Al2O3-SiO2 crystallized glass of the present invention has a thermal expansion coefficient of 30 × 10 at 30 to 750°C. -7 / ℃ or below, 25×10 -7 / ℃ or below, 20×10 -7 / ℃ or below, 18×10 -7 / ℃ or below, 16×10 -7 / ℃ or below, 14×10 -7 / ℃ or below, 13×10 -7 / ℃ or below, 12×10 -7 / ℃ or below, 11×10 -7 Below / ℃, 10×10 -7 / ℃ or below, 9×10 -7 / °C or below, 8×10 -7 / °C or below, 7×10 -7 / °C or below, 6×10 -7 / °C or below, 5×10 -7 / °C or below, 4×10 -7 / °C or below, particularly 3×10 -7 / °C or below is preferred. When dimensional stability and / or thermal shock resistance are particularly required, -15×10 -7 / °C ~ 15×10 -7 / °C, -12×10 -7 / °C ~ 12×10 -7 / °C, -10×10 -7 / °C ~ 10×10 -7 / °C, -8×10 -7 / °C ~ 8×10 -7 / °C, -6×10 -7 / °C ~ 6×10 -7 / °C, -5×10 -7 / °C ~ 5×10 -7 / °C, -4.5×10 -7 / °C ~ 4.5×10 -7 / °C, -4×10 -7 / °C ~ 4×10 -7 / °C, -3.5×10 -7 / °C ~ 3.5×10 -7 / °C, -3×10 -7 / °C ~ 3×10 -7 / °C, -2.5×10 -7 / °C ~ 2.5×10 -7 / °C, -2×10 -7 / °C ~ 2×10 -7 / °C, -1.5×10 -7 / °C ~ 1.5×10 -7 / °C, -1×10 -7 / °C ~ 1×10 -7 / °C, particularly -0.5×10 -7 / °C ~ 0.5×10 -7 / °C is preferred.

[0105] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a Young's modulus of 60 to 120 GPa, 70 to 110 GPa, 75 to 110 GPa, 75 to 105 GPa, 80 to 105 GPa, particularly 80 to 100 GPa. If the Young's modulus is too low or too high, the crystallized glass is likely to be damaged.

[0106] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a rigidity modulus of 25 to 50 GPa, 27 to 48 GPa, 29 to 46 GPa, particularly 30 to 45 GPa. If the rigidity modulus is too low or too high, the crystallized glass is likely to be damaged.

[0107] The Li2O-Al2O3-SiO2-based crystallized glass of the present invention preferably has a Poisson's ratio of 0.35 or less, 0.32 or less, 0.3 or less, 0.28 or less, 0.26 or less, particularly 0.25 or less. If the Poisson's ratio is too large, the crystallized glass is likely to be damaged.

[0108] Regarding the crystalline glass before crystallization of the Li2O-Al2O3-SiO2-based crystallized glass of the present invention, the density is 2.30 to 2.60 g / cm 3 、2.32 to 2.58 g / cm 3 、2.34 to 2.56 g / cm 3 、2.36 to 2.54 g / cm 3 、2.38 to 2.52 g / cm 3 、2.39 to 2.51 g / cm 3 、particularly 2.40 to 2.50 g / cm 3 is preferable. If the density of the crystalline glass is too small, the gas permeability before crystallization deteriorates, and the glass may be contaminated during the storage period. On the other hand, if the density of the crystalline glass is too large, the weight per unit area increases, making handling difficult.

[0109] Regarding the Li2O-Al2O3-SiO2-based crystallized glass (after crystallization) of the present invention, the density is 2.40 to 2.80 g / cm 3 、2.42 to 2.78 g / cm 3 、and 2.44 to 2.76 g / cm 32.46~2.74 g / cm³ 3 , especially 2.47~2.73 g / cm³ 3 It is preferable that the density of the crystallized glass is too low, which may impair its gas permeability. On the other hand, if the density of the crystallized glass is too high, the weight per unit area becomes large, making it difficult to handle. Furthermore, the density of the crystallized glass (after crystallization) serves as an indicator of whether the glass has crystallized sufficiently. Specifically, for the same glass, the higher the density (the greater the density difference between the original glass and the crystallized glass), the more crystallization has progressed.

[0110] The density change rate of the Li2O-Al2O3-SiO2-based crystallized glass of the present invention is {(density after crystallization (g / cm³) 3 )-Density before crystallization (g / cm³) 3 )) / Density before crystallization (g / cm³) 3 The density is defined as )} × 100 (%), and the density before crystallization is the density after holding the molten glass at 700°C for 30 minutes and cooling it to room temperature at 3°C / min, while the density after crystallization is the density after crystallization treatment under predetermined conditions. The density change rate is preferably 0.01~10%, 0.05~8%, 0.1~8%, 0.3~8%, 0.5~8%, 0.9~8%, 1~7.8%, 1~7.4%, 1~7%, 1.2~7%, 1.6~7%, 2~7%, 2~6.8%, 2~6.5%, 2~6.3%, 2~6.2%, 2~6.1%, 2~6%, 2.5~5%, 2.6~4.5%, and 2.8~3.8%. Reducing the density change rate before and after crystallization can reduce the rate of breakage after crystallization, and also reduce scattering between the glass and the glass matrix, making it possible to obtain crystallized glass with high transmittance. In particular, in the region where the TiO2 content is less than 0.5% (especially 0.05% or less), scattering can be significantly reduced in order to reduce coloring factors other than absorption such as TiO2, contributing to improved transmittance.

[0111] The Li2O-Al2O3-SiO2 crystallized glass of the present invention may be subjected to chemical strengthening or other treatments. The treatment conditions for chemical strengthening should be appropriately selected by considering the glass composition, degree of crystallinity, type of molten salt, etc., and determining the treatment time and temperature accordingly. For example, a glass composition containing a large amount of Na2O, which may be present in the residual glass, may be selected to facilitate chemical strengthening after crystallization, and the degree of crystallinity may be intentionally lowered. The molten salt may contain one or more alkali metals such as Li, Na, and K. Furthermore, in addition to the usual single-stage strengthening, multi-stage chemical strengthening may be selected. In addition, by treating the Li2O-Al2O3-SiO2 crystallized glass of the present invention with chemical strengthening or other treatments before crystallization, the Li2O content on the sample surface can be reduced compared to the inside of the sample. When such glass is crystallized, the degree of crystallinity on the sample surface becomes lower than that inside the sample, the coefficient of thermal expansion on the sample surface becomes relatively higher, and compressive stress due to the difference in thermal expansion can be introduced into the sample surface. Furthermore, if the crystallinity of the sample surface is low, the glass phase will be more abundant on the surface, and depending on the selection of the glass composition, chemical resistance and gas barrier properties can be improved.

[0112] Next, a method for producing the Li2O-Al2O3-SiO2 crystallized glass of the present invention will be described.

[0113] First, a batch of raw materials prepared to produce glass of the above composition is placed in a glass melting furnace, melted at 1500-1750°C, and then molded. During glass melting, methods such as flame melting using a burner, or electromelting using electric heating may be used. Melting by laser irradiation or plasma is also possible. Furthermore, the sample shape can be plate-like, fibrous, film-like, powder-like, spherical, hollow, etc., and there are no particular restrictions.

[0114] Next, the obtained crystalline glass (crystallizable glass before crystallization) is heat-treated to crystallize it. The crystallization conditions are as follows: first, nucleation is carried out at 700-950°C (preferably 750-900°C) for 0.1-100 hours (preferably 1-60 hours), followed by crystal growth at 800-1050°C (preferably 800-1000°C) for 0.1-50 hours (preferably 0.2-10 hours). In this way, a transparent Li2O-Al2O3-SiO2-based crystalline glass in which β-quartz solid solution crystals precipitate as the main crystal can be obtained. Note that the heat treatment may be carried out at a specific temperature only, or it may be heat-treated in stages by holding it at two or more temperature levels, or it may be heated while applying a temperature gradient.

[0115] Furthermore, crystallization may be promoted by applying or irradiating sound waves or electromagnetic waves. In addition, the cooling rate of the crystallized glass heated to a high temperature may be carried out using a specific temperature gradient, or it may be carried out using a temperature gradient of two or more levels. If sufficient thermal shock resistance is to be obtained, it is desirable to control the cooling rate to sufficiently relax the structure of the remaining glass phase. The average cooling rate from 800°C to 25°C is preferably 3000°C / min, 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 especially 5°C / min or less in the inner part of the thickness of the crystallized glass furthest from the surface. Furthermore, if long-term dimensional stability is desired, it is preferable that the cooling rate be 2.5°C / min or less, 1°C / min or less, 0.5°C / min or less, 0.1°C / min or less, 0.05°C / min or less, 0.01°C / min or less, 0.005°C / min or less, 0.001°C / min or less, 0.0005°C / min or less, and especially 0.0001°C / min or less. Except in cases where physical strengthening treatment such as air cooling or water cooling is performed, it is desirable that the cooling rate of the crystallized glass is close to the cooling rate of the glass surface and the cooling rate of the innermost part of the wall thickness furthest from the glass surface. The value obtained by dividing the cooling rate of the innermost part of the wall thickness furthest from the surface by the cooling rate of the surface is preferably 0.0001~1, 0.001~1, 0.01~1, 0.1~1, 0.5~1, 0.8~1, 0.9~1, and especially 1. Being close to 1 makes it less likely for residual strain to occur at all positions in the crystallized glass sample, making it easier to obtain long-term dimensional stability. The surface cooling rate can be estimated using contact thermometers or radiation thermometers, while the internal temperature can be estimated by placing a high-temperature crystallized glass in a cooling medium, measuring the heat quantity and heat quantity change rate of the cooling medium, and using this numerical data along with the specific heat and thermal conductivity of the crystallized glass and the cooling medium. [Examples]

[0116] The present invention will be described below based on examples, but the present invention is not limited to the following examples. Tables 1 to 42 show examples of the present invention (samples No. 1 to 131).

[0117] [Table 1]

[0118] Table 2

[0119] Table 3

[0120] Table 4

[0121] Table 5

[0122] Table 6

[0123] Table 7

[0124] Table 8

[0125] Table 9

[0126] Table 10

[0127] Table 11

[0128] Table 12

[0129] Table 13

[0130] Table 14

[0131] Table 15

[0132] Table 16

[0133] Table 17

[0134] Table 18

[0135] Table 19

[0136] Table 20

[0137] Table 21

[0138] Table 22

[0139] Table 23

[0140] Table 24

[0141] Table 25

[0142] Table 26

[0143] Table 27

[0144] Table 28

[0145] Table 29

[0146] Table 30

[0147] Table 31

[0148] Table 32

[0149] Table 33

[0150] Table 34

[0151] Table 35

[0152] Table 36

[0153] Table 37

[0154] Table 38

[0155] Table 39

[0156] Table 40

[0157] Table 41

[0158] Table 42

[0159] First, glass batches were obtained by mixing each raw material in the form of oxides, hydroxides, carbonates, nitrates, etc., to produce glass with the compositions listed in each table (the compositions listed in each table are the analytical values ​​of the glass actually produced). The obtained glass batches were placed in a crucible containing platinum and rhodium, a reinforced platinum crucible without rhodium, a refractory crucible, or a quartz crucible, melted at 1600°C for 4 to 100 hours, then heated to 1650 to 1680°C and melted for 0.5 to 20 hours, roll-formed to a thickness of 5 mm, and then heat-treated in an annealing furnace at 700°C for 30 minutes, and the annealing furnace was cooled to room temperature at 100°C / h to obtain crystalline glass. The melting was carried out by the electromelting method, which is widely used in the development of glass materials.

[0160] Furthermore, using the glass composition of sample No. 27, it was confirmed that the glass composition, while in contact with a liquid or solid, can be melted by laser irradiation. It was also confirmed that the glass composition, while in contact only with gas while the sample is suspended by gas being introduced from around it, can be laser-melted. In addition, it was confirmed that the glass composition can be molded into hemispherical, spherical, fibrous, and powder forms by pressing, redrawing, spraying, etc., after being pre-melted in an electric furnace or the like. Furthermore, using the glass compositions of samples No. 28 to 49, it was confirmed that melting is possible in a continuous furnace combining burner heating and electrical heating, and that they can be molded into block, flake, and hollow forms by rolling, film, and lot methods using dielectric heating. In addition, using the glass composition of sample No. 15, it was confirmed that it can be molded into thin sheets, tubes, and valve forms by updrawing, downdrawing, slitting, overflow (fusion), and hand-blowing methods. Furthermore, using the glass composition of sample No. 59, we confirmed that the glass molten material could be poured onto a liquid with a higher specific gravity than sample No. 59, and then solidified into a plate-like form by subsequent cooling. The glass produced by either method could be crystallized under the conditions described in the table.

[0161] The Pt and Rh content of the samples was analyzed using an ICP-MS instrument (Agileint 8800, manufactured by Agileint Technology). First, the prepared glass samples were crushed and wetted with pure water, then melted by adding perchloric acid, nitric acid, sulfuric acid, hydrofluoric acid, etc. Afterward, the Pt and Rh content of the samples was measured by ICP-MS. The Pt and Rh content of each sample was determined based on a calibration curve created using pre-prepared Pt and Rh solutions of known concentrations. The measurement modes were Pt: He gas / HMI (low mode) and Rh: HEHe gas / HMI (medium mode), with mass numbers of Pt: 198 and Rh: 103. The Li2O content of the prepared samples was analyzed using an atomic absorption spectrometer (ContrAA600, manufactured by Analytical Jena). The melting process of the glass samples and the use of calibration curves were basically the same as for the Pt and Rh analysis. Furthermore, for other components, they were measured by ICP-MS or atomic absorption spectrometry, similar to Pt, Rh, and Li2O. Alternatively, glass samples with known concentrations, previously analyzed using ICP-MS or atomic absorption spectrometry, were used as calibration curve samples. A calibration curve was then created using an XRF analyzer (RIGAKU ZSX PrimusIV), and the actual content of each component was determined from the XRF analysis values ​​of the measured samples based on this calibration curve. During XRF analysis, the tube voltage, tube current, exposure time, etc., were adjusted as needed according to the analytical component.

[0162] Each crystalline glass sample was heat-treated at 750-900°C for 0.75-60 hours to induce nucleation, followed by further heat treatment at 800-1000°C for 0.25-3 hours to induce crystallization. Afterward, it was heat-treated at 700°C for 30 minutes and cooled to room temperature at 100°C / h. The resulting crystallized glass was evaluated for transmittance, diffuse transmittance, brightness, chromaticity, precipitated crystals, average crystallite size, thermal expansion coefficient, density, Young's modulus, shear modulus, Poisson's ratio, and appearance. Transmittance, brightness, and chromaticity of the uncrystallized crystalline glass were measured using the same methods as for the crystallized glass. Additionally, the β-OH value, viscosity, and liquidus temperature were measured for the crystalline glass.

[0163] Transmittance, brightness, and chromaticity were evaluated using a spectrophotometer on a 3mm thick crystallized glass plate that had been optically polished on both sides. A JASCO V-670 spectrophotometer was used for the measurements. The V-670 was equipped with the ISN-723 integrating sphere unit, and the measured transmittance corresponds to the total light transmittance. The measurement wavelength range was 200-1500nm, the scan speed was 200nm / min, the sampling pitch was 1nm, and the bandwidth was 5nm in the 200-800nm ​​wavelength range and 20nm in other wavelength ranges. Before measurement, baseline correction (100% adjustment) and dark measurement (0% adjustment) were performed. Dark measurement was performed with the barium sulfate plate attached to the ISN-723 removed. Using the measured transmittance, the tristimulus values ​​XYZ were calculated based on JIS Z 8781-42013 and its corresponding international standards, and lightness and chromaticity were calculated from each stimulus value (light source C / 10°). Furthermore, the diffuse transmittance of crystallized glass was measured using the same equipment as above, with the barium sulfate plate attached to the ISN-723 removed, and the sample was placed on the equipment.

[0164] Precipitated crystals were evaluated using an X-ray diffractometer (Rigaku Smart Lab, a fully automatic, multi-purpose horizontal X-ray diffractometer). The scan mode was 2θ / θ measurement, the scan type was continuous scan, the scattering and divergence slit width was 1°, the receiving slit width was 0.2°, the measurement range was 10-60°, the measurement step was 0.1°, and the scan speed was 5° / min. The principal crystal and grain size were evaluated using the analysis software installed in the instrument package. The precipitated crystal species identified as the principal crystal is shown in the table as "β-quartz solid solution" (β-Q). The average crystallite size of the principal crystal was calculated using the measured X-ray diffraction peaks based on the Debeye-Scherrer method. For the measurement used to calculate the average crystallite size, the scan speed was 1° / min.

[0165] The coefficient of thermal expansion was evaluated using the average linear thermal expansion coefficient measured at temperatures of 30–380°C and 30–750°C with crystallized glass samples processed to 20 mm × 3.8 mmφ. A NETZSCH dilatometer was used for the measurements. In addition, the glass transition point of the crystalline glass before crystallization was evaluated by measuring the thermal expansion curve in the temperature range of 30–750°C using the same instrument and calculating its inflection point.

[0166] Young's modulus, shear modulus, and Poisson's ratio were measured at room temperature using a free-resonance elastic modulus analyzer (JE-RT3, manufactured by Nippon Techno Plus) on a plate-shaped sample (40 mm × 20 mm × 20 mm) whose surface was polished with an abrasive solution dispersed with 1200-grade alumina powder.

[0167] Density was evaluated using the Archimedes method.

[0168] The strain point and annealing point were evaluated using the fiber elongation method. Fiber samples were prepared from crystalline glass using a manual guided method.

[0169] The β-OH value was determined by measuring the transmittance of the glass using an FT-IR Frontier (Perkin Elmer) and calculating it using the following formula. The scan speed was 100 μm / min, and the sampling pitch was 1 cm. -1 The number of scans was set to 10 per measurement.

[0170] β-OH value = (1 / X)log10(T1 / T2) X: Glass thickness (mm) T1: Reference wavelength 3846cm -1 Transmittance (%) T2: Hydroxyl group absorption wavelength 3600 cm -1 Minimum transmittance in the vicinity (%)

[0171] High-temperature viscosity was evaluated using the platinum ball pulling method. For evaluation, the bulk glass sample was crushed into appropriate dimensions, taking care to avoid incorporating air bubbles, and placed into an alumina crucible. The alumina crucible was then heated to a molten state, 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, and the temperature at each viscosity was determined.

[0172] The liquidus temperature was evaluated using the following method. First, glass powder, uniformly sized to 300-500 micrometers, was packed into a platinum boat measuring approximately 120 × 20 × 10 mm and placed in an electric furnace, where it was melted at 1600°C for 30 minutes. Afterward, it was transferred to an electric furnace with a linear temperature gradient and immersed for 20 hours to allow devitrification to precipitate. After air-cooling the sample to room temperature, the devitrification precipitated at the interface between the platinum boat and the glass was observed, and the temperature at the devitrification site was calculated from the electric furnace's temperature gradient graph to determine the liquidus temperature. Furthermore, the obtained liquidus temperature was interpolated into the high-temperature viscosity curve of the glass, and the viscosity corresponding to the liquidus temperature was defined as the liquidus viscosity. The initial phase of the glass described in each table was found to be mainly ZrO2 based on X-ray diffraction, compositional analysis (using a Hitachi scanning electron microscope, Hitachi S3400N TyPE2, and Horiba EMAX ENERGY EX250X).

[0173] The appearance was evaluated by visually checking the color tone of the crystallized glass. Visual inspections were performed against both a white and a black background, under indoor lighting and under sunlight (conducted at 8:00, 12:00, and 16:00 on clear and cloudy days in January, April, July, and October). A comprehensive judgment of the color tone was made based on the results of each visual inspection.

[0174] As is clear from Tables 1-42, the crystallized glass samples No. 1-131 in the examples were colorless and transparent in appearance, had high transmittance, and had a thermal expansion coefficient of almost 0, indicating that they were sufficiently crystallized. Furthermore, the rate of change in transmittance before and after crystallization was small.

[0175] Figure 1 shows the transmittance curve of sample No. 27 before crystallization, and Figure 2 shows the transmittance curve of sample No. 27 after crystallization. From Figures 1 and 2, it is clear that the rate of change in transmittance before and after crystallization is small.

[0176] Furthermore, when the crystallized glass sample No. 27 was immersed in a KNO3 melt at 475°C for 7 hours, a compressive stress layer was formed on the sample surface (compressive stress: 110 MPa, compression depth: 10 micrometers). [Examples]

[0177] Tables 43 and 44 show examples of the present invention (samples A to J). Table 45 shows comparative examples of the present invention (samples K to M).

[0178] [Table 43]

[0179] [Table 44]

[0180] [Table 45]

[0181] Samples A to M, as described in Tables 31, 32, and 33, were prepared in the same manner as in Example 1, and their β-OH values ​​before crystallization and densities after crystallization were measured. The relationship between β-OH values ​​and densities for samples A to E is shown in Figure 3, the relationship between β-OH values ​​and densities for samples F to J is shown in Figure 4, and the relationship between β-OH values ​​and densities for samples K to M is shown in Figure 5.

[0182] As is clear from Figures 3 and 4, for crystallized glass with a low TiO2 content that tends to be colorless and transparent, the density increased and crystallization progressed as the β-OH value increased. On the other hand, as is clear from Figure 5, for crystallized glass with a high TiO2 content that tends to be yellow, crystallization progressed to a similar extent regardless of the β-OH value. This result succinctly demonstrates the effect of the present invention in efficiently providing Li2O-Al2O3-SiO2-based crystallized glass that suppresses yellow discoloration caused by TiO2, Fe2O3, etc., while ensuring transparency. Although Tables 31 and 32 are described as representative examples of the present invention, similar effects have been confirmed in other examples described in this patent. Furthermore, although the crystallization temperature is fixed to a certain combination in the examples described in Tables 31 and 32, it has been confirmed that similar effects can be obtained with other combinations of crystallization temperatures. The crystallization temperature can be changed in any way depending on the desired firing time and the characteristics of the crystallized glass. [Industrial applicability]

[0183] The Li2O-Al2O3-SiO2 crystallized glass of the present invention is suitable for applications such as front windows of oil stoves and wood-burning stoves, substrates for high-tech products such as color filters and substrates for image sensors, setters for firing electronic components, light diffusers, furnace tubes for semiconductor manufacturing, masks for semiconductor manufacturing, optical lenses, dimensional measuring components, communication components, building components, containers for chemical reactions, top plates for induction cooktops, heat-resistant tableware, heat-resistant covers, window glass for fire doors, components for astronomical telescopes, and components for space optics.

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