JP5713188B2 - Method for producing Li2O-Al2O3-SiO2 crystallized glass - Google Patents

Description

The present invention relates to a method for producing Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass.

Conventionally, front windows such as oil stoves and wood stoves, substrates for high-tech products such as color filters and image sensor substrates, setters for firing electronic components, shelf plates for microwave ovens, top plates for electromagnetic cooking, window glass for fire doors, etc. Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass is used as the material. For example, Patent Documents 1 to 3 and the like, main crystal as β- quartz solid solution _{(Li 2 O · Al 2 O} 3 · nSiO 2 [ provided that n ≧ 2]) and β- spodumene solid solution _{(Li 2 O · Al 2 O} 3 · nSiO ₂ [provided that n ≧ 4]) formed by precipitating _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass is disclosed.

Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass has excellent thermal characteristics because it has a low coefficient of thermal expansion and high mechanical strength. In addition, since the precipitated crystal can be changed by changing the heat treatment conditions in the crystallization process, a transparent crystallized glass (β-quartz solid solution is precipitated) and a white opaque crystallized glass (β -Spodumene solid solution) can be produced and can be used properly according to the application.

Meanwhile _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass are the high glass viscosity, it is melted at a temperature exceeding 1400 ° C.. For this reason, As ₂ O ₃ and Sb ₂ O ₃ which can generate a large amount of clarification gas at the time of melting at a high temperature are used as a clarifier. However, As ₂ O ₃ and Sb ₂ O ₃ are highly toxic and may contaminate the environment during the glass production process and waste glass processing. Therefore, a method for melting glass without using As ₂ O ₃ or Sb ₂ O ₃ has been studied. For example, methods using SnO ₂ or Cl as alternative fining agents for As ₂ O ₃ and Sb ₂ O ₃ have been proposed (Patent Documents 4 and 5).

In addition, for the purpose of preventing the generation of pulsation and the prevention of devitrification, the melting equipment for Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass is platinum or a platinum alloy (hereinafter referred to as a surface of a feeder or a molding apparatus in contact with glass). , Abbreviated as platinum). In this case, there is a case where these devices are energized to heat or keep the glass warm.

Japanese Examined Patent Publication No. 39-21049 Japanese Patent Publication No. 40-20182 JP-A-1-308845 JP 11-228180 A Japanese Patent Laid-Open No. 11-228181

When melting Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass without using As ₂ O ₃ or Sb ₂ O ₃ in a melting facility that uses electric heating, such as electric heating, platinum, etc. It has been found that a phenomenon in which a large amount of reboil bubbles caused by electricity occurs from the surface of the apparatus, and it becomes difficult to obtain glass with good bubble quality. This phenomenon is a phenomenon that is difficult to recognize in a laboratory-based melting evaluation test using a crucible.

An object of the present invention is Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass capable of suppressing bubble defects due to electric reboil, although it does not contain As ₂ O ₃ or Sb ₂ O _3. It is to provide a manufacturing method.

Method for producing a _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass of the present invention is to use the melt equipment comprising platinum or a platinum alloy device, _{Li 2} O-Al 2 using heating by electric A method for producing Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass, in which O ₃ —SiO ₂ -based crystallized glass is melted, molded, and then crystallized, when the viscosity log η is 4.0 The glass melt was prepared so as to be a crystalline glass having an electric resistance of 4.4 Ω · cm or more, a liquid phase viscosity of log η of 4.35 or more, and substantially free of As ₂ O ₃ and Sb ₂ O ₃ . It is characterized by using a batch.

Here, “Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass” includes Li ₂ O, Al ₂ O ₃ and SiO ₂ as essential components, and β-spodumene and / or β-quartz solid solution. It means crystallized glass as the main crystal. “Li ₂ O—Al ₂ O ₃ —SiO ₂ crystalline glass” includes Li ₂ O, Al ₂ O ₃ and SiO ₂ as essential components, and β-spodumene and / or β-quartz solid solution is formed by heat treatment. It means an amorphous glass having the property of precipitating as a main crystal. “Platinum or platinum alloy device” means a device whose contact surface with molten glass is formed of platinum or a platinum alloy. An apparatus in which a contact portion with glass is coated with platinum or the like is also included. “Electric heating” includes direct energization heating of molten glass by an electrode, energization heating to a melting facility including a platinum or platinum alloy apparatus, and the like. “The electrical resistance when the viscosity log η is 4.0” means the electrical resistance of the glass when the viscosity log η of the glass melted by melting the batch shows 4.0. The viscosity is determined by the platinum ball pulling method, and the electrical resistance of the glass is a value measured by a two-terminal method using a 1 kHz AC power source. “Liquid phase viscosity” is measured by putting glass in a platinum boat, melting it at 1550 ° C. for 30 minutes, and then placing it in a temperature gradient furnace for 20 hours. Furthermore, the viscosity of the glass corresponding to the liquidus temperature is obtained by using a platinum ball pulling method. “Substantially not containing As ₂ O ₃ and Sb ₂ O ₃ ” means that these components are not actively used as raw materials. As a more objective standard, it means that the content of As ₂ O ₃ is less than 1000 ppm and the content of Sb ₂ O ₃ is less than 1000 ppm, including the case where it is mixed as an impurity. “Batch” includes not only raw materials such as natural raw materials and synthetic raw materials but also waste glass cullet.

According to the above configuration, without using _As 2 _{O 3} and _Sb 2 _{O 3} may contaminate the environment during the process of manufacturing steps and waste glass of the glass, _{Li 2} O-Al 2 with excellent bubble quality It becomes possible to obtain an O ₃ —SiO ₂ -based crystallized glass.

In the present _invention, Li 2 O, you prepare a batch as the total amount of Na ₂ O and _{K 2} O is 4.7 wt% or less.

  According to the above configuration, the electrical resistance of the glass when the viscosity log η is 4.0 can be easily set to 4.4 Ω · cm or more.

In the present invention, it is preferable to prepare a batch as Li 2 _O is 4.1 wt% or less.

  According to the above configuration, the electrical resistance of the glass when the viscosity log η is 4.0 can be easily set to 4.4 Ω · cm or more, and an amount of β-spodumene necessary for obtaining desired characteristics can be obtained. It becomes easy to precipitate the β-quartz solid solution.

In the present invention, it is preferable to prepare the batch so that Al ₂ O ₃ is 24 mass% or less.

  According to the said structure, it becomes possible to suppress effectively precipitation of a mullite and to make liquid phase viscosity high. As a result, it becomes possible to melt the glass in a more viscous state, in other words, in a state with higher electrical resistance.

In the present invention, it is preferable to use SnO ₂ and / or Cl as a fining agent.

According to the above configuration, without using _As 2 _{O 3} and _Sb 2 _{O 3,} it is possible to obtain an excellent _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass bubble quality.

In the present invention, it is preferable to prepare a batch as SnO ₂ is 0.1 to 0.5 mass%.

According to the above configuration, without using _As 2 _{O 3} and _Sb 2 _{O 3,} it is possible to obtain an excellent _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass bubble quality.

In the present invention, it is preferable to prepare the batch so that TiO ₂ is 1.5% by mass or more.

If an attempt is made to increase the electric resistance without using As ₂ O ₃ and Sb ₂ O ₃ , the resulting transparent crystallized glass tends to become cloudy. This phenomenon occurs particularly when Li ₂ O is reduced in order to increase the electrical resistance. The reason is that when Li ₂ O, As ₂ O ₃ and Sb ₂ O ₃ are reduced, the crystallinity is lowered and crystallization is less likely to occur uniformly. Therefore, if the above configuration is adopted, it becomes easy to prevent white turbidity of the transparent crystallized glass.

In the present invention, in _{mass%, SiO 2 50~67%, Al} 2 O 3 12~24%, Li 2 O 2.5~4.1%, 0~5% MgO, 0~10% ZnO, BaO _{0~8%, Na 2 O 0~0.5%} , K 2 O 0~0.5%, TiO 2 1.5~8%, ZrO 2 0~2.4%, P 2 O 5 0~7 % prepare a batch to contain.

In the present invention, heating by electricity Ru electrical heating der to platinum or platinum alloy device. Here, “the heating by electricity is the current heating to the platinum or platinum alloy device” means that at least the current heating is used to heat or keep the molten glass, and a heating method other than the current heating, such as an electrode, is used. It does not exclude the combination of direct current heating used or combustion heating with a burner.

  When glass is heated by energizing a platinum or platinum alloy device, electric reboil is likely to occur. Therefore, it becomes easier to enjoy the effect of the present invention in the case of the melting equipment having the above configuration.

  In the present invention, the platinum or platinum alloy device is preferably a feeder or a molding device.

  When the feeder or the molding apparatus is made of platinum or a platinum alloy, electric reboil is likely to occur. Therefore, it becomes easier to enjoy the effect of the present invention in the case of the melting equipment having the above configuration.

It is explanatory drawing which shows an example of glass manufacturing equipment.

  The electric reboil is a phenomenon in which the following reaction occurs between the glass melt and a conductor (platinum or the like) in contact with the glass melt, and oxygen bubbles are generated at the portion that hits the positive electrode.

Positive electrode: 2O ²⁻ → O ₂ (reboil bubble) + 4e ⁻
Negative electrode: O ₂ + 4e ⁻ → 2O ²⁻
Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass contains an alkali metal component (such as Li ₂ O) in the glass composition. Further, since this type of glass is easily devitrified, molding is performed in a low viscosity region, in other words, in a high temperature region. In other words, this glass system is in a state where the electric resistance of the molten glass is low and electricity easily flows. Here, when electricity is used to heat the molten glass, if a potential difference occurs between different portions of the molten glass, a circuit through platinum or the like is likely to be formed, and oxygen bubbles are generated at the platinum / molten glass interface corresponding to the positive electrode. Will occur. In particular, when the glass is continuous up to the forming device or the transfer device located downstream thereof, such as roll forming, a circuit is easily formed, and electric reboil is very likely to occur.

Incidentally As ₂ O ₃ and Sb ₂ O ₃ which is used as a refining agent, with an increase in temperature in the melt-refining process, oxygen is released into the glass changes valence.

M ₂ O ₅ → M ₂ O ₃ + O ₂ (M: As, Sb)
Furthermore, oxygen is absorbed with the temperature fall in clarification-molding.

M ₂ O ₃ + O ₂ → M ₂ O ₅
Due to the reaction when the temperature is lowered, bubbles generated by the electric reboil are absorbed by As ₂ O ₃ and Sb ₂ O ₃ and disappear. In Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass that does not contain As ₂ O ₃ or Sb ₂ O ₃ , the bubble problem due to electric reboil became apparent as As ₂ O ₃ and Sb ₂ O _3. This is because there is no component capable of absorbing reboyl foam.

It has been found that increasing the resistance of the glass melt at the feeder and the molding part is effective for making it difficult to generate electric reboil in a glass that does not contain As ₂ O ₃ or Sb ₂ O ₃ . Specifically, when the high-temperature viscosity log η is 4.0, it is 4.4 Ω · cm or more, preferably 4.7 Ω · cm or more.

  The resistance of the glass melt is affected by the alkali amount and viscosity. Less resistance and higher viscosity are preferred because resistance increases. However, there is a problem of devitrification if the viscosity is too high. In order to solve the problem, it is necessary to design the composition so as to increase the liquid phase viscosity so that devitrification does not occur even if the viscosity at the feeder or the molding part is increased. Therefore, the present invention is characterized in that the batch is prepared so that the electrical resistance of the glass is increased and at the same time the liquid phase viscosity of the glass is increased. The specific liquid phase viscosity of the glass is 4.35 or more, preferably 4.40 or more, more preferably 4.45 or more in terms of log η.

Will now be described _{Li 2 O-Al 2 O 3} -SiO 2 system manufacturing method of the crystallized glass of the present invention.

First, when the high temperature viscosity log η is 4.0, the electrical resistance is 4.4 Ω · cm or more, the liquid phase viscosity is log η of 4.35 or more, and the glass does not substantially contain As ₂ O ₃ and Sb ₂ O _3. Prepare the batch as follows. In the following description, “%” means “mass%” unless otherwise specified. Moreover, the raw material which comprises a batch is not limited to an oxide etc., It can be used with various forms, such as various compounds and glass cullet.

In order to make the electrical resistance when the high temperature viscosity log η is 4.0 to 4.4 Ω · cm or more, the content of alkali metal components such as Li ₂ O, Na ₂ O, and K ₂ O contained in the batch is reduced. This can be achieved. Specifically, the batch is such that the total amount of Li ₂ O, Na ₂ O and K ₂ O is less than 4.7%, 4.5% or less, 4.4% or less, particularly 4.3% or less. Is preferably prepared. Further, it is desirable that alkali metal components other than Li ₂ O which is a crystal component of β-spodumene and β-quartz solid solution, that is, Na ₂ O and K ₂ O are not contained as much as possible. Specifically, it is preferable to prepare the batch so that the contents of Na ₂ O and K ₂ O are each 0.5% or less. It is desirable to reduce the content of _{K 2} O than Na ₂ O. Specifically, it is preferable to prepare the batch so that the content of K ₂ O is 0.4% or less, particularly 0.3% or less.

The liquidus viscosity logη to 4.35 or more can be achieved by reducing the content of _Al 2 _{O 3} and Li ₂ O contained in the batch.

This type of glass devitrifying crystal seed is often mullite with a high precipitation rate. That is, if the precipitation of mullite is suppressed, the liquid phase viscosity can be increased. Deposition of mullite affected content of _Al 2 _{O 3,} mullite is likely to precipitate as is rich _Al 2 _{O 3.} From such a viewpoint, it is preferable to prepare the batch so that the content of Al ₂ O ₃ is 24% or less, 23% or less, particularly 22.6% or less.

Further, the devitrified crystal seed when the composition is designed so that mullite does not precipitate is β-spodumene. In order to further increase the liquid phase viscosity, it is necessary to increase the liquid phase viscosity of β-spodumene. The liquid phase viscosity of β-spodumene increases as the amount of Li ₂ O decreases. From such a viewpoint, it is preferable to prepare the batch so that the content of Li ₂ O is 4.1% or less, 4.0% or less, and particularly 3.9% or less.

As described above, the content of the alkali metal component is preferably small from the viewpoint of increasing the electrical resistance and the liquid phase viscosity. Alkali metal component way is to promote the dissolution of SiO ₂ in the dissolving step, there is a function to reduce the non-refining bubbles. Even if the alkaline component is reduced to prevent electrical reboil as described above, a product with good foam quality cannot be obtained if the number of unclear bubbles increases. In particular, when As ₂ O ₃ or Sb ₂ O ₃ having a high clarification effect is not used, unclear bubbles may be remarkably increased due to a decrease in the alkali metal component. In such a case, it is necessary to limit the amount of SiO ₂ . Specifically, it is desirable to prepare the batch so that the content of SiO ₂ is 67% or less, particularly 66.5% or less.

In addition, SnO ₂ or Cl can be used as an alternative clarifier for As ₂ O ₃ or Sb ₂ O ₃ for the purpose of reducing unclear bubbles. In addition, Cl has the fault that it corrodes a metal mold | die and a molding roll, and tends to reduce the surface quality of glass. Therefore, it is better to use SnO ₂ preferentially over Cl. However, although the details of the mechanism are unknown, SnO ₂ has a function of increasing the precipitation rate of β-spodumene, so the usage amount should be strictly regulated. Specifically, it is preferable to prepare the batch so that the SnO ₂ content is 0.5% or less, 0.4% or less, and particularly 0.3% or less. In order to obtain a SnO ₂ clarification effect, it is desirable to prepare a batch so that the SnO ₂ content is 0.1% or more.

By appropriately adjusting the content of various components as described above, it becomes possible to obtain Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass with excellent foam quality, but transparent crystallized glass When trying to obtain, there is a case where the crystallized glass tends to become cloudy. This white turbidity can be solved by containing a large amount of TiO ₂ . Specifically, it is preferable to prepare the batch so that the content of TiO ₂ is 1.5% or more, 1.6% or more, and particularly 1.8% or more. ZrO ₂ has the same effect as TiO _2. However, increasing the amount of ZrO ₂ is not preferable because the devitrification temperature increases and the liquidus viscosity decreases. From this point of view, the batch should be prepared so that the ZrO ₂ content is 2.4% or less.

In addition to the above, various components can be added to the batch. For example, a raw material containing a Ca component can be added to the batch so that the content of CaO is 5% or less. Further as the content of B ₂ O ₃ is 10% or less, it can be added to raw material containing B component to the batch. Various components can be added as a colorant. For example, a raw material containing a V component can be added to the batch so that the content of V ₂ O ₅ is 1.5% or less, 1.0% or less, and particularly 0.8% or less. Further as the content of Nd ₂ O ₃ is 1% or less, it can be added to raw material containing Nd component to the batch.

The preferred batch composition in the present invention is as follows.
_{(1) SiO 2 50~67%,} Al 2 O 3 12~24%, Li 2 O 2.5~4.1%, 0~5% MgO, 0~10% ZnO, BaO 0~8%, Na ₂ O 0-0.5%, K ₂ O 0-0.5%, TiO ₂ 1.5-8%, ZrO ₂ 0-2.4%, P ₂ O ₅ 0-7%
_{(2) SiO 2 55~67%,} Al 2 O 3 16~24%, Li 2 O 3.0~4.1%, MgO 0.1~2.5%, 0~3% ZnO, BaO 0~ _{4%, Na 2 O 0~0.5%} , K 2 O 0~0.5%, TiO 2 1.5~5%, ZrO 2 0~2.3%, P 2 O 5 0~5%
_{(3) SiO 2 58~67%,} Al 2 O 3 18~24%, Li 2 O 3.2~4.1%, MgO 0.1~2.0%, ZnO 0~2.5%, BaO _{0~3%, Na 2 O 0~0.5%} , K 2 O 0~0.5%, TiO 2 1.5~5%, ZrO 2 0~2.3%, P 2 O 5 0~3 %
Next, the glass raw material is put into a melting facility containing platinum or a platinum alloy, and melted and molded. In the melting equipment used in the present invention, the molten glass is heated and kept warm using electricity in at least a part of the equipment. The molten glass is heated by a method in which a platinum or platinum alloy heating element is brought into contact with the glass melt, more specifically by direct current heating with an electrode in a melting tank, current heating to a feeder, a molding apparatus, or the like. Done. In particular, adopting electric heating to a feeder or the like is advantageous for melting and forming Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass having a strong tendency to devitrify. It is preferable to employ a tank kiln capable of continuous production as the melting equipment. In the case of the glass having the above composition, the glass raw material is preferably melted at a maximum temperature of 1600 to 1800 ° C. for about 20 to 200 hours. In addition, when any heating method is adopted, electric reboil may be generated. In particular, when energization heating is performed on a feeder, a molding apparatus, etc., electric reboil is likely to occur.

Subsequently, the glass melt is formed into a desired shape to obtain a Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystalline glass formed body. As a molding method, various methods such as roll molding, press molding, and float molding can be employed.

  As described above, when an electric heating method is employed, oxygen bubbles may be generated on the surface of platinum or the like due to electric reboil. However, in the present invention, since the batch is prepared so that the electric resistance of the glass at the time of melting and forming becomes high, it becomes difficult for electricity to flow into the glass melt, and the electric reboil phenomenon can be suppressed.

  When roll forming or float forming is employed, the crystalline glass formed body is cut (separated) after forming. In particular, when the cutting process is performed after the glass temperature is sufficiently low, in other words, after the viscosity of the glass is sufficiently high, the high temperature glass in the melting equipment and the low temperature glass in the molding machine or the diver machine are continuous It becomes. In such a case, a thermoelectromotive force due to a temperature difference is likely to occur, and electric reboil is more likely to occur. Therefore, it is preferable to adjust the viscosity of the glass immediately after exiting from the outlet of the glass melt, for example, the orifice, to 3.0 or more by log η so that the temperature difference between the glass inside and outside the melting facility is small. Further, when a molding method in which glass is supplied with low viscosity, for example, a roll molding method, is employed, reboil may occur due to thermoelectromotive force due to a temperature difference between the upstream glass and the downstream glass of the molding apparatus. In this case, it is desirable to adjust so that the temperature difference between the upstream side and the lower amount side of the molding apparatus is as small as possible.

Subsequently, the Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystalline glass molded body is held at 700 to 800 ° C. for 1 to 4 hours for nucleation, and in the case of forming a transparent crystallized glass, 800 to 950 ° C. And β-quartz solid solution is precipitated by heat treatment for 0.5 to 3 hours. In addition, when a white opaque crystallized glass is formed, a β-spodumene solid solution may be precipitated by heat treatment at 1050 to 1250 ° C. for 0.5 to 2 hours after nucleation.

In this way, it is possible to obtain a Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass excellent in foam quality despite substantially not containing As ₂ O ₃ or Sb ₂ O ₃ . The obtained Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass can be subjected to various uses such as post-processing such as cutting, polishing, bending, stretching, and painting on the surface. To be served.

Hereinafter, a manufacturing method of the _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass of the present invention will be described based on examples.

  Table 1 shows Examples (Nos. 1 and 2) and Comparative Examples (Nos. 3 to 7) using the method of the present invention.

  FIG. 1 shows a manufacturing facility used in this embodiment. The production equipment includes a melting equipment 10 having a melting tank 11 and a feeder 12, a roll forming machine 20, a delivery machine 30, a slow cooling furnace (not shown), and a cutting machine (not shown). The melting tank 11 is made of a refractory material, and is provided with an oxyfuel burner that heats and melts the supplied batch. The feeder 12 is connected to the melting tank 11 and conveys the glass melt melted in the melting tank 11 to the molding machine. The feeder 12 is made of platinum. In addition, platinum terminals (not shown) connected to a power source (not shown) are installed at both ends of the feeder so that the feeder body can be energized. In addition, a platinum orifice 13 for continuously flowing out the molten glass is provided at the end of the feeder 12. A roll forming machine 20 including a pair of rollers is installed below the orifice. A delivery machine is provided below the roll forming machine 20 to convey the glass in the form of ribbon by roll forming to a slow cooling furnace. A slow cooling furnace and a cutting machine are installed downstream of the delivery machine.

  Next, a method for preparing each sample used in the manufacturing facility will be described.

First, each raw material was prepared in the form of oxide, hydroxide, carbonate, nitrate, etc. so as to obtain a glass having the composition shown in the table, and mixed uniformly. Thereafter, this raw material batch was put into the dissolution tank 11 and dissolved at a dissolution efficiency of 2.5 m ² / (t / day). The melted glass melt is supplied to the roll forming machine through the feeder 12 that is energized and heated. The ribbon-shaped glass formed into a plate shape by a roll forming machine is conveyed to a slow cooling furnace (not shown) by the delivery machine 4 and gradually cooled and strain-removed. Then, it cut | disconnected with the cutting machine and obtained the crystalline glass molded object.

  The obtained crystalline glass molded body was heated at 780 ° C. for 30 minutes for nucleation, and then subjected to a heat treatment at 890 ° C. for 10 minutes to grow crystals, thereby completing crystallization. About the obtained transparent crystallized glass, the presence or absence of white turbidity was evaluated.

As is apparent from Table 1, sample Nos. Using the method of the present invention were used. In the samples 1 and 2, although no As ₂ O ₃ or Sb ₂ O ₃ was used, there were few unclear bubbles and the generation of electric reboil could be suppressed. Moreover, it turned out that it can manufacture without the cloudiness after crystallization.

  The electric resistance was measured by a two-terminal method using a 1 kHz AC power source.

  The liquid phase viscosity was measured as follows. First, the pulverized product of the crystalline glass molded body was put into a platinum boat and heated at 1500 ° C. for 30 minutes for remelting. Next, the platinum boat was put into a temperature gradient furnace and held for 20 hours, and then taken out to obtain the liquidus temperature. Furthermore, the viscosity of the glass in the liquid phase viscosity was determined by the platinum ball pulling method. Note that the crystal species to be measured for the liquidus temperature is a crystal precipitated at the highest temperature among β-spodumene and mullite, which has a high precipitation rate and is likely to cause a problem during molding. EPMA can be used to identify the crystal species.

  Presence or absence of mullite precipitation was confirmed from the form of crystals precipitated by microscopic observation.

  Presence / absence of uncleared bubbles is determined by measuring the number of bubbles collected at the outlet of the dissolution tank and converting the number of bubbles per kg to less than 10 / kg. Was determined.

  The presence or absence of reboil is calculated by converting the number of bubbles in the glass collected at the outlet of the melting tank and the glass after molding into the number of bubbles per kg, and the number of bubbles in the glass after molding is the number of glasses before stirring. The case of less than 2 times was determined as “none”, and the case of 2 times or more was determined as “present”.

  The presence or absence of cloudiness was evaluated by placing the crystallized glass on a black mount and observing the appearance under a fluorescent lamp.

The method of the present invention includes a front window for petroleum stoves, wood stoves, etc., substrates for high-tech products such as color filters and image sensor substrates, setters for firing electronic components, shelf plates for microwave ovens, top plates for electromagnetic cooking, fire doors It is suitable as a method for producing Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass used as various materials such as window glass for glass without using As ₂ O ₃ or Sb ₂ O _3. . In particular, it is effective when energizing and heating a feeder or the like for the purpose of preventing devitrification of the Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass.

DESCRIPTION OF SYMBOLS 10 Melting equipment 11 Dissolution tank 12 Feeder 13 Orifice 20 Roll forming machine 30 Divery machine

Claims (7)

Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallinity using a melting facility including an apparatus made of platinum or a platinum alloy whose contact surface with the molten glass is formed of platinum or a platinum alloy and using electric heating melting glass, after forming, a _{Li 2 O-Al 2 O 3} -SiO 2 system manufacturing method of a crystallized glass to be crystallized, in _{mass%, SiO 2 50~67%, Al} 2 O 3 12~ _{24%, Li 2 O 1~4.1%} , 0~5% MgO, 0~10% ZnO, BaO 0~8%, Na 2 O 0~0.5%, K 2 O 0~0.5% TiO ₂ 1.5-8%, ZrO ₂ 0-2.4%, P ₂ O ₅ 0-7%, the total amount of Li ₂ O, Na ₂ O and K ₂ O is 4.7% by mass hereinafter, and the electrical resistance of the glass melt when the viscosity logη is 4.0 4.4Ω · cm or more, Phase viscosity 4.35 or more log [eta, and As ₂ a O ₃ and Sb ₂ O ₃ with use batch prepared so as to be substantially free crystalline glass, electrically heating the platinum or platinum alloy device _{Li 2 O-Al 2 O 3} -SiO 2 system manufacturing method of a crystallized glass, characterized by. _{Li 2 O-Al 2 O 3} -SiO 2 system manufacturing method of the crystallized glass according to claim 1, characterized in that Li ₂ O to prepare a batch to be equal to or less than 4.1 wt%. _{Li 2 O-Al 2 O 3} -SiO 2 system manufacturing method of a crystallized glass as claimed in claim 1 or 2, characterized that the Al ₂ O ₃ is prepared batches so that 24 mass% or less. _{Li 2 O-Al 2 O 3} -SiO 2 system manufacturing method of the crystallized glass according to any one of claims 1 to 3, wherein the use of SnO ₂ and / or Cl as a fining agent. _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized according to any one of claims 1-4 in which SnO ₂ is characterized by preparing a batch so that 0.1 to 0.5 wt% Glass manufacturing method. Production of _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass according to any one of claims 1 to 5, characterized in that the TiO ₂ is prepared batches so that 1.5 wt% or more Method. _{Li 2 O-Al 2 O 3} -SiO 2 system manufacturing method of the crystallized glass according to any one of claims 1 to 6, wherein the platinum or platinum alloy system is the feeder or shaping device.