CN203333457U - Settling tank for manufacturing glass plate, device made of platinum or platinum alloy, and glass plate manufacturing device - Google Patents

Abstract

The utility model relates to a settling tank for manufacturing a glass plate, a device made of platinum or platinum alloy, and a glass plate manufacturing device. In the glass manufacturing process, the settling tank 102 is heated by electrification to heat molten glass. The settling tank 102 is characterized by at least comprising a thick wall part which is provided with a thick wall with greater thickness than other parts, and the thick wall part is in the position where the temperature of molten glass reaches the maximum region.

Description

Clarifying tanks for the manufacture of glass plates, devices of platinum or platinum alloys, glass plate manufacturing apparatus

technical field

The utility model relates to a clarification tank for manufacturing glass plates, a device made of platinum or platinum alloy, and a glass plate manufacturing device. the

Background technique

In the manufacture of glass, a large number of devices made of refractory metals such as platinum or platinum alloys are used in order to handle high-temperature molten glass. Especially in glass substrates for liquid crystal displays (LCD) or glass substrates for organic EL displays, since the melting temperature and melting temperature of glass raw materials with a very small alkali content are higher than those of other glass products, the conveying pipes and tanks of molten glass are almost made of platinum. Or a manufacturing device made of a platinum alloy. Furthermore, since the above-mentioned glass substrates for LCDs and glass substrates for organic EL displays are required to be free of foam, in the process called "clarification process", the melting temperature is set at 1500°C or higher to eliminate foam in the molten glass. Foam. Therefore, in the manufacturing apparatus of the glass plate for LCD glass substrates, the manufacturing apparatus which consists of platinum or a platinum alloy which has the best durability at high temperature among refractory metals is used in large quantities. However, even refractory metals are oxidized at temperatures as high as glass melts. At this time, the production equipment of platinum or platinum alloy volatilizes during oxidation, and oxidation pitting occurs in which the components constituting the production equipment become thinner. In particular, when manufacturing glass plates for LCD glass substrates or glass substrates for organic EL displays, platinum or platinum alloys have specific portions exposed to high temperatures in the clarification process described above, and oxidation pitting of the above-mentioned platinum occurs conspicuously. The clarification process of the above-mentioned LCD glass substrate or glass substrate for an organic EL display is performed by adding a clarifier to a glass raw material. When the molten glass rises from low temperature to high temperature, the clarifying agent reacts with the valence change of the metal constituting the clarifying agent as follows, that is, M _x O _y → M _x1 O _y1 + zO ₂ (M is a metal element, x, x1, y , y1, and z are real numbers), and the oxygen generated at this time expands the entrained bubbles during melting to perform suspension degassing. As a glass clarifier, diarsenic pentoxide or antimony oxide was used in the past, but in recent years, tin oxide, which has almost no environmental impact, has been used in consideration of the impact on the environment. However, compared with diarsenic pentoxide or antimony oxide, the temperature at which tin oxide reacts with changes in the valence state is high, and in the production equipment that performs the clarification process, the temperature of the molten glass and the production equipment is about 1650°C or higher. Therefore, the service life of devices made of refractory metal is at most several years. The cost increases if it is necessary to purchase devices every few years, especially those made of expensive precious metals such as platinum or platinum alloys.

Therefore, for example, as described in Patent Document 1 (JP-A-2010-502550), a technique for minimizing oxidation pitting of tanks made of refractory metal in a glass manufacturing system by coating the surface has been proposed. the

Utility model content

Problems to be solved by the utility model

However, even with the above method, sometimes the oxidation pitting of the refractory metal device cannot be completely suppressed, and a method capable of effectively prolonging the service life of the refractory metal device is still required. the

This invention was made|formed in view of the said subject, and it aims at providing the apparatus which can effectively prolong the lifetime of the apparatus made of refractory metal. the

technical means to solve problems

1. A settling tank made of refractory metal and used for the manufacture of glass plates, characterized in that:

The clarification tank is made of platinum or platinum alloy, and the tank of the clarification tank has a space for accommodating the gas discharged through degassing,

The said clarification tank contains at least a thick part which has a thick wall thicker than other parts, and this thick part is located in the part where the temperature of molten glass reaches the highest range. the

2. According to the clarification tank described in technical scheme 1, it is characterized in that:

The clarification tank has a plurality of power supply devices arranged along the flow direction of the molten glass,

The region where the temperature of the molten glass reaches the highest in the clarification tank is located in the upstream side region of the flow direction center of the molten glass in the clarification tank. the

3. According to the clarification tank described in technical scheme 1, it is characterized in that:

The length of the said thick part is 1/25 - 1/2 of the full length of the said clarification tank. the

4. According to the clarification tank described in technical scheme 2, it is characterized in that:

The clarification tank includes a pipe main body and at least three power supply devices arranged at both ends and the middle of the pipe main body,

The thick-walled portion spans at least half of the outer circumference of the pipe main body, and is at least provided on the top of the pipe main body. the

5. According to the clarification tank described in technical scheme 4, it is characterized in that:

The entire outer periphery of the said clarification tank has the said thick part. the

6. The clarification tank according to any one of technical solutions 1 to 5, characterized in that:

The outer peripheral surface of the clarification tank is provided with a refractory oxide spray coating. the

7. A device made of platinum or platinum alloy for manufacturing glass plates, characterized in that: said device made of platinum or platinum alloy has a tubular shape elongated toward the length direction,

The device made of platinum or platinum alloy has a thick wall thicker than other parts at least in part of the part which is less than the melting point of the platinum or platinum alloy and which is in contact with molten glass whose melting point is 150°C or higher department. the

8. The device made of platinum or platinum alloy according to technical solution 7, characterized in that:

The entire periphery of the device made of platinum or platinum alloy has the thick-walled portion. the

9. The device made of platinum or platinum alloy according to technical solution 7 or 8, characterized in that:

The outer peripheral surface of the device made of platinum or platinum alloy is provided with a refractory oxide spraying layer. the

10. A glass plate manufacturing device, characterized in that it comprises:

Melting tank for melting glass raw materials to form molten glass;

The first conveying pipe is used for conveying molten glass;

The clarification tank as described in any one of technical schemes 1 to 6 is used to clarify the molten glass transported from the first delivery pipe;

The second conveying pipe is used to convey the clarified molten glass;

The stirring tank is used to stir the clarified molten glass transported from the second conveying pipe to homogenize the molten glass;

The third conveying pipe is used to convey the homogenized molten glass, and

The molding device is used to shape the homogenized molten glass delivered from the third delivery pipe. the

11. A glass plate manufacturing device, characterized in that it comprises:

Melting tank for melting glass raw materials to form molten glass;

The first conveying pipe is used for conveying molten glass;

A device made of platinum or a platinum alloy as described in any one of technical schemes 7 to 9, used to clarify the molten glass transported from the first delivery pipe;

The second conveying pipe is used to convey the clarified molten glass;

The stirring tank is used to stir the clarified molten glass transported from the second conveying pipe to homogenize the molten glass;

The third conveying pipe is used to convey the homogenized molten glass, and

The molding device is used to shape the homogenized molten glass delivered from the third delivery pipe. the

The inventor of the utility model, as a result of intensive research on the method for prolonging the life of the device made of refractory metal, found that:

(i) In a device made of refractory metal, especially in a specific part that reaches a high temperature compared with other areas, the oxidation and volatilization of the refractory metal are more severe than other parts, and holes appear in this part within 1 to 2 years. the

(ii) For example, when the device is a device made of tubular refractory metal for clarifying molten glass (settling tank), the specific part is located not only at the part in contact with the high-temperature molten glass, but also between the glass and the inner wall of the tube The part where the air contacts, that is, the local top position in the length direction of the tube. the

The utility model is completed in view of the above viewpoints, and relates to a clarification tank for manufacturing glass plates of the present utility model, which is made of platinum or platinum alloy, wherein the tank of the clarification tank has a tank for containing the gas discharged from degassing space. The clarification process is to heat the molten glass by heating the clarification tank with electricity. It is preferable that the clarification tank has a thick-walled part thicker than other parts of the clarification tank at least in the clarification tank including the region where the temperature of the molten glass reaches the highest. the

Here, the clarification tank has a thick-walled part thicker than other parts of this clarification tank in the clarification tank at least including the place where the temperature of molten glass reaches the highest range. According to this configuration, the life of the device made of refractory metal can be effectively extended. the

And, it relates to the clarification tank for manufacturing the glass plate of the present invention, the clarification tank is preferably heated by passing electricity between a plurality of power supply devices arranged along the flow direction of the molten glass, and the temperature of the molten glass in the clarification tank The highest region is located on the upstream side from the center of the flow direction of the molten glass in the clarification tank. the

Moreover, the clarification tank for manufacturing a glass plate which this invention relates to is a clarification tank for manufacturing a glass plate including the process of pouring molten glass into the device made of platinum or platinum alloy extending in the longitudinal direction. A device made of white gold or platinum alloys is used to heat molten glass by energizing it. the

A device made of platinum or platinum alloy, characterized in that at least part of the part in contact with molten glass has a thicker wall than other parts, wherein the temperature of the molten glass is lower than that of platinum or platinum alloy. Melting point, and 150°C or more below the melting point. the

Here, the device made of platinum or platinum alloy has a thicker part than other parts at least partially in the part in contact with the molten glass, wherein the temperature of the molten glass is lower than the melting point of platinum or platinum alloy. , and more than 150°C below the melting point. Therefore, it is possible to effectively prolong the life of the device made of refractory metal. the

Furthermore, it is preferable that it is the clarification tank for manufacturing the glass plate of this invention, and a clarification tank has a thick-walled part over the whole periphery. the

utility model effect

According to the clarification tank related to the present invention, the service life of the device made of refractory metal can be effectively extended. the

Description of drawings

Fig. 1 is related to the glass plate manufacturing process flowchart of the utility model embodiment;

Fig. 2 is related to the glass plate production line of the utility model embodiment;

Fig. 3 is a clarification tank related to an embodiment of the present invention. the

Detailed ways

Below, an embodiment of the utility model will be described in conjunction with the accompanying drawings. In addition, the following description is only an example of the present invention, and the present invention is not limited thereto. the

(1) A device made of tubular refractory metal (settling tank)

The device made of refractory metal and extended in the longitudinal direction related to an embodiment of the present invention is a device made of refractory metal, which is used to manufacture glass plates and is called clarification tank 102 made of refractory metal (clarification tube) )installation. The clarification tank 102 is a device that heats and clarifies molten glass at least locally. the

As shown in FIG. 3 , the clarification tank 102 includes a pipe main body 102a, and at least three power supply devices 201 provided at both ends and approximately in the middle of the pipe main body 102a. the

The pipe main body 102a has a cylindrical shape. The maximum inner diameter of the pipe main body 102a is, for example, 300 to 400 mm. The pipe main body 102a is preferably made of platinum or a platinum alloy, although it is made of a refractory metal. The pipe main body 102a generates heat by the energization of the first power supply device 201a, the second power supply device 201b, and the third power supply device 201c, and heats the molten glass by the Joule heat. The 1st power supply device 201a, the 2nd power supply device 201b and the 3rd power supply device 201c are made of flange or electrodes drawn from the flange, and the electric current is between the 1st power supply device 201a and the 2nd power supply device 201b, and the 2nd power supply device 201b and the third power supply device 201c. As described above, by heating the tube body 102 made of platinum or platinum alloy, the temperature of the molten glass in the tube body 102a can be easily controlled to be high even in the manufacture of a glass plate containing tin oxide as a clarifying agent. The temperature at which tin oxide reacts with changes in valence. the

Here, it is preferable that the temperature of molten glass becomes the highest in the region between the 1st power supply device 201a and the 2nd power supply device 201b. Or, it is preferable that the temperature of the pipe main body 102a becomes the highest in the area between the 1st power supply device 201a and the 2nd power supply device 201b. If the temperature of the molten glass becomes the highest in the region between the first power supply device 201a and the second power supply device 201b of the pipe main body 102a, then in the region between the second power supply device 201b and the third power supply device 201c, When the temperature of the molten glass becomes the highest, the clarification time can be extended in the state of the molten glass at the temperature and viscosity suitable for clarification (defoaming). That is, if the temperature of the molten glass is made the highest in the area between the first power supply device 201a and the second power supply device 201b of the pipe main body 102a, it is not necessary to extend the length of the molten glass flow direction in the pipe main body 102a, and it is possible to effectively Perform clarification (degassing). In order to make the temperature of the molten glass the highest in the area between the first power supply device 201a and the second power supply device 201b of the pipe main body 102a, it is possible to pass more current to the first power supply device 201a than to the third power supply device 201c. accomplish. Furthermore, the region where the temperature of the pipe body 102a becomes the highest or the region where the temperature of the molten glass becomes the highest in the pipe body 102a is preferably a region closer to the upstream side than the center of the flow direction of the molten glass in the pipe body 102a. That is, as shown in FIG. 3 , the lower thick portion 102b is preferably provided in a region closer to the upstream side than the center X in the flow direction F of the molten glass in the pipe main body 102a. the

In the pipe main body 102a, it is preferable that the resistance of the portion including at least the region where the temperature of the molten glass reaches the highest in the pipe main body 102a (the entire area excluding the pipe main body 102a) is smaller than that of other portions. Alternatively, it is preferable that the pipe body 102a has at least a region where the temperature of the pipe body 102a reaches the highest value (the entire region except the pipe body 102a ) to have lower electrical resistance than other parts. For example, the pipe main body 102a preferably has a thick portion 102b thicker than other portions. It is preferable that the pipe main body 102a has the thick part 102b in at least a part of a portion where the pipe main body 102a is in contact with molten glass in a predetermined temperature range. More specifically, the pipe main body 102a preferably has a thicker portion 102b than other parts including at least a region where the temperature of the molten glass reaches the highest temperature in the pipe main body 102a (the entire region except the pipe main body 102a). Alternatively, it is preferable that the pipe main body 102a includes at least a region where the temperature of the pipe main body 102a reaches the highest value (excluding the entire region of the pipe main body 102a), and has a thicker portion 102b than other parts. The portion of the pipe body 102a that is in contact with the molten glass in the predetermined temperature range, the portion of the pipe body 102a that includes at least the region where the temperature of the molten glass reaches the highest (the entire area excluding the pipe body 102a), or at least the temperature of the pipe body 102a The portion reaching the highest area (the entire area excluding the pipe body 102 a ) is a portion that divides the longitudinal position of the thick portion 102 b in the pipe body 102 a. In addition, the predetermined temperature range in this embodiment is preferably lower than the melting point of the refractory metal constituting the pipe main body 102a, and lower than the melting point by 150°C or more. In addition, the predetermined temperature range is more preferably lower than the melting point, and lower than the melting point by 100°C or more. More preferably, the specified temperature range is lower than the melting point of the refractory metal and more than 80°C lower than the melting point. For example, when the tube body 102a is made of platinum, it is preferable that the temperature of the molten glass is lower than the melting point of platinum, that is, about 1770°C and higher than 1620°C, more preferably higher than 1670°C, most preferably higher than 1690°C A portion of the pipe main body 102a that is in contact with the region has a thick portion 102b. The total length of the thick portion 102b is preferably at least 100 mm, more preferably at least 150 mm, most preferably at least 200 mm. Or the total length of the thick wall portion 102b is less than the total length of the clarifier 102, preferably 1/25 to 1/2 of the clarifier 102 total length, most preferably less than 1/10 to 1/4 of the clarifier 102 total length. In addition, the total length means the total length in the flow direction in which the molten glass flows. Moreover, the total length of the clarification tank 102 in this embodiment refers to the total length of the device made of platinum or platinum alloy required to remove bubbles from the molten glass to the outside of the molten glass, wherein the device has a molten glass and an air phase. contact space. the

If the total length of the thick portion 102b becomes longer, the amount of platinum used will increase and the cost will increase. On the other hand, if the total length of the thick wall portion 102b is too short, the temperature of the molten glass becomes the highest or the temperature of the tube main body 102a becomes the highest, and the platinum or platinum alloy is most likely to oxidize or volatilize, and platinum cannot be sufficiently suppressed. Or the oxidation or volatilization of the platinum alloy makes it difficult to prolong the life of the clarification tank 102 . For example, if the thickness could be increased across the overall length of the platinum or platinum alloy comprising clarifier tank 102, long life could indeed be extended. However, platinum or platinum alloys are extremely expensive raw materials, and it is unrealistic to sufficiently thicken the overall length of platinum or platinum alloys constituting the clarification tank 102 from the viewpoint of cost. Therefore, in this embodiment, the service life of the clarification tank 102 is prolonged by increasing the thickness of the part of the clarification tank 102 where the oxidation or volatilization of platinum or platinum alloy is more severe than other parts. the

The thick-walled portion 102b can be partially provided across a part of the outer circumference of the pipe main body 102a, preferably over half the circumference, more preferably across the entire circumference. However, when the thick portion 102b is partially provided across the entire circumference of the pipe main body 102a, the thick portion 102b is preferably provided so as to cover the top of the pipe main body 102b. The thickness of the thick wall portion 102b is preferably adjusted in consideration of the material of the device made of refractory metal, the cross-sectional area of the thick wall portion 102b, the temperature of the molten glass, etc., for example, it is more than 10% thicker than other parts, more preferably More than 20%, more preferably more than 50%, most preferably more than 100%. When the pipe main body 102a having a thickness of 1 mm other than the thick portion 102b has the thick portion 102b, the thickness of the thick portion 102b is preferably more than 1.1 mm, more preferably more than 1.2 mm, more preferably more than 1.5 mm, and most preferably more than 1.5 mm. is more than 2mm. the

In addition, the pipe main body 102a may be a pipe formed integrally with the thick portion 102b and a portion other than the thick portion 102b, or may be a pipe joined to a member forming the thick portion 102b. Furthermore, the pipe main body 102a may be a pipe obtained by splicing a plurality of pipes. For example, the tube main body 102a may be a tube in which tubes of different thicknesses are spliced together, and the thick tube serves as the thick wall portion 102b. the

In order to ensure the quality and characteristics of the glass plate, it is necessary to heat the molten glass in the pipe main body 102a to a predetermined temperature in the clarification tank 102 . For example, in order to reduce the foam value of a glass plate, it is necessary to raise the temperature of molten glass in the clarification tank 102 to the temperature suitable for clarification. Here, the temperature suitable for clarification of the molten glass varies depending on the clarifier used and the components and properties of the glass. The glass plate of this example preferably contains tin oxide as a clarifying agent. Tin oxide functions as a clarifying agent, that is, the temperature at which oxygen is effectively released exceeds 1600°C, and oxygen is released violently as the temperature rises. That is, when tin oxide is contained as a clarifier, the temperature suitable for clarification exceeds 1620 degreeC, More preferably, it exceeds 1650 degreeC. the

On the other hand, the glass plate shown in this example is an alkali-free glass that does not substantially contain R' ₂ O (however, R' is at least one selected from Li, Na, and K) or contains only 0.10 mass %～2.0% by mass R' ₂ O micro-alkali glass plate. The above-mentioned non-alkali or slightly alkali glass has higher viscosity at high temperature (high temperature viscosity) than alkali glass having an alkali content exceeding 2.0% by mass. For example, the temperature of alkali-free or slightly alkali glass is 1500℃～1750℃ when logη=2.5.

Here, the floating speed of the bubbles in the molten glass is affected by the viscosity of the molten glass, and the lower the viscosity of the molten glass, the faster the floating speed of the bubbles. For efficient clarification, the viscosity of the molten glass is optimally, for example, 200 to 800 poise. Therefore, in order to clarify the non-alkali glass or slightly alkali glass and lower the viscosity of the molten glass, it is necessary to raise the temperature of the molten glass further than that of the alkali glass. More specifically, in the manufacture of an alkali-free glass plate or a slightly alkali glass plate, it is necessary to make the temperature of the molten glass in the clarification tank 102, for example, 1650 degreeC or more. In addition, the above-mentioned clarification refers to the process of expelling the bubbles in the molten glass out of the molten glass and performing defoaming. the

In the above case, the temperature of the pipe main body 102a may exceed the temperature at which the refractory metal constituting the pipe main body 102a, such as platinum, is easily oxidized or volatilized. In order to release gas components from the molten glass, it is preferable that there is a gap between the liquid level of the molten glass in the clarification tank 102 and the inner wall of the pipe main body 102a of the clarification tank 102 . That is, the clarification tank 102 has a space for accommodating the degassed and discharged gas in the pipe main body 102a. This space is preferably such that the bubbles are sufficiently detached from the molten glass, and the distance between the liquid surface and the inner wall (the distance between the liquid surface and the inner wall surface facing the liquid surface) in this space is preferably greater than the inner diameter of the pipe main body 102a. 1%, and less than 50%, more preferably greater than 5% of the inner diameter of the pipe main body 102a, and less than 15%. However, since the portion of the pipe body 102a in contact with the air in the space transfers the heat generated by energization to the glass only by radiant electric heat, the temperature of the portion in contact with the molten glass is relatively high. Since the temperature of the molten glass flowing in the pipe body 102a made of refractory metal reaches 1700°C, for example, the top of the pipe body 102a is only in contact with the air inside, so the temperature is higher than 1700°C. Even if the pipe main body 102a made of refractory metal, if the temperature of the pipe main body reaches a high temperature exceeding a predetermined temperature, it will be oxidized or volatilized, and holes will appear. Furthermore, platinum or platinum at the part of the tube body 102a in contact with the space is more likely to be oxidized than other parts of the tube body 102a that are not in contact with the space and other pipes that are not in contact with the air inside the tube. Therefore, in order to suppress oxidation or volatilization of the refractory metal, at least a part of the portion of the pipe main body 102a that reaches a predetermined temperature range may be strengthened to be thicker than other portions. In this way, even if the thick part becomes thin due to oxidation or volatilization, it will take time for holes to appear, and the durability can be increased. In addition, it is estimated that the rise in temperature of this portion can be suppressed due to various reasons such as a decrease in resistance of this portion or an increase in heat capacity. For example, since the electric resistance of the thick wall part 102b is smaller than other parts in the clarification tank 102 total length, heat generation can be reduced compared with other parts. According to this configuration, oxidation and volatilization of the thick portion 102b can be suppressed, and the lifetime can be extended. the

On the other hand, once the current is applied to the tube main body 102a, the current flows more to the part with low resistance. This is because the larger the cross-sectional area where the current flows, the smaller the resistance. Since the calorific value Q when a current is passed through a resistance value R is expressed by the formula I ² *R, even if the resistance decreases, as more current flows, the calorific value may become larger. Therefore, if only the thick-walled part 102b is provided on the top of the pipe main body 102a where the refractory metal is easily oxidized and volatilized, the temperature around the top where the thick-walled part 102b is provided may become higher because the current concentrates on the thick-walled part 102b. If the above-mentioned thick-walled part spans more than half the circumference of the pipe main body, it is more preferable to set the thick-walled part 102b across the entire circumference. Since the current is concentrated in the thick-walled part 102b, compared with when the thick-walled part 102b is not provided, this can be avoided. Part of the increase in calorific value.

For example, the relationship between the thickness occupied by the thick portion 102b and the entire circumference of the pipe body 102a and the current, resistance, and heat generation is calculated as follows. Assuming that the pipe main body 102a is made of platinum and has a thickness of 1mm except for the thick part 102b, the thick part 102b with a thickness of 2mm is located between the first power supply device 201a and the second power supply device on which the pipe main body 102a is attached. At the same time, the temperature across the pipe main body 102 a reaches the entire circumference of the portion of the full length L mm (hereinafter, referred to as a high temperature portion) which is particularly high. Furthermore, assuming that the pipe body 102a does not have the thick portion 102b, the electrical resistance of the portion at the same position as the high temperature portion is RΩ. The current flowing across the entire circumference of the high temperature portion of the tube body 102a is 1 ampere. At this time, since the resistance R=ρ (specific resistance)*L (length)/A (cross-sectional area), the cross-sectional area of the thick-walled portion 102b is twice the cross-sectional area of the tube main body 102a without the thick-walled portion 102b. The resistance _R1 of the thick wall portion 102b is R/2 when the pipe main body 102a is supplied with current. The calorific value Q ₁ of the thick portion 102 b is Q ₁ [J·s]=(I) ² *R/2. The calorific value Q ₂ of the high-temperature portion when there is no thick portion 102 b is Q ₂ [J·s]=(I) ² *R. Therefore, when a current of 1 ampere is passed across the entire circumference of the high-temperature portion to the pipe main body 102a, Q ₁ /Q ₂ =1/2, and when energized, the heat generation value of the thick-walled portion 102b reaches half. Next, assuming that the thickness of the thick-walled portion 102b is 20% greater than that of the other portions, that is, 1.2mm, and the thick-walled portion 102b is set across the half cycle of the high-temperature portion of the total length Lmm, it can be considered that the current flows between the half cycle of the thick-walled portion 102b and the other half cycle of the thick-walled portion 102b. flow in a half circuit connected in series. At this time, assuming that the current flowing across the entire circumference of the high-temperature portion of the tube main body 102a is I ampere, the current flowing in the thick wall portion 102b is I ₁ , and the current flowing in the other half-circle portion is I ₂ , then I=I ₁ +I ₂ . Since the resistance R ₁ of the thick wall part 102b =2R/1.2, and the resistance R ₂ of the other half-cycle part =2R, therefore, I=1.2E/2R+E/2R (E is voltage), E=2RI/2.2, I ₁ =E/R ₁ =1.2I/2.2. The calorific value Q ₁ of the thick portion 102 b is Q ₁ [J·s]=(1.2I/2.2) ² *2R/1.2. Since there is no thick-walled part 102b, the calorific value of the middle half of the high-temperature part is Q ₂ = (I/2) ² * 2R, and Q ₁ /Q ₂ is approximately equal to 0.992. When energized, there is a thicker wall than that without the thick-walled part 102b. The calorific value of the portion 102b is small.

In addition, for the tubular refractory metal device made of platinum or platinum alloy, for example, a sufficient amount of the refractory oxide may be sprayed on the outer surface of the clarification tank 102 by thermal spraying. Using the structure of thermal spraying and thick-walled part for platinum or platinum alloy can further suppress the volatilization of platinum or platinum alloy, and can prolong the service life of the device made of refractory metal, such as clarification tank 102 . In addition, the method of thermal spraying is not particularly limited, and plasma spraying or flame spraying can be used. However, from the viewpoint of improving the coating density and improving the bonding of platinum or platinum alloys to refractory oxides, plasma spraying is the best. Furthermore, as a material containing a refractory oxide, a material containing MgO, TiO ₂ , and Zr ₂ O is preferable. In particular, materials containing refractory oxides preferably contain zirconia, more preferably fully stabilized zirconia, most preferably stabilized by Ca compounds, Mg and/or Y compounds. Thermal spraying with a material containing a refractory oxide can have a thermal expansion coefficient close to that of the platinum or platinum alloy used in the clarification tank 102, and can prevent the thermally sprayed refractory oxide-containing material from falling off from the platinum or platinum alloy. , wherein the refractory oxide contains fully stabilized zirconia as described above.

For at least part of the portion of the pipe body 102a made of refractory metal in the clarification tank 102, which is less than the melting point of the refractory metal and in contact with molten glass whose melting point is 150°C or higher, for example, at least the part of the molten glass in the clarification tank Simulation calculations were performed on the effect of increasing the temperature of the pipe main body 102a having the thick portion 102b thicker than other portions in the region where the temperature reaches the highest range. Assume that the pipe main body 102a is made of platinum and rhodium alloy (melting point is about 1840°C), has a total length of 4000mm, a diameter of about 350mm, and a thickness of 1mm, between the first power supply device 201a and the second power supply device 201b, across from the first 2. The entire circumference of the power supply device 201b with a total length of 150 mm from a position of about 300 mm to a position of about 450 mm has the above-mentioned thick portion 102b with a thickness of 1.2 mm. At the top of the position where the thick portion is provided, when a glass plate is manufactured using an existing clarification tank composed of a pipe body without the thick portion 102b, the temperature of the pipe body made of an alloy of platinum and rhodium becomes significantly high, and Areas where oxidation or volatilization of platinum is significant. Assume that the clarification tank 102 is energized and heated by the first power supply device 201a, the second power supply device 201b, and the third power supply device 201c, and at the same time, a current of about 6000A is passed between the first power supply device 201a and the second power supply device 201b. The molten glass in the clarification tank 102 is heated, and the temperature of the molten glass at the position where the thick part 102b is provided becomes about 1700 degreeC or more. And it was simulated how much the top temperature of the pipe main body 102a thick wall part 102b of the clarification tank 102 became at this time. As a result, the temperature at the top of the thick portion 102b of the pipe main body 102a is about 10°C lower than the temperature of 1820°C without the thick portion 102a, and is about 1810°C. From this simulation result, it turns out that if this utility model is utilized, the lifetime of glass manufacturing apparatuses, such as the clarification tank 102 made of refractory metal, can be extended effectively. Here, platinum or platinum alloys are rapidly oxidized or volatilized as they reach high temperatures. Therefore, 10° C. above 1800° C. is a large temperature difference from the viewpoint of preventing oxidation or volatilization of platinum or platinum alloys. the

In addition, as for the simulation method to obtain the above results, as long as those skilled in the art can use the following commercially available software, the detailed description will be omitted here, but in brief, in order to simulate the platinum alloy A mathematical model was used for the temperature distribution of the pipe main body 102a of the clarification tank 102 . Specifically, as the characteristics of the tube body 102a, for example, the resistivity and thermal conductivity of the platinum alloy constituting the tube body 102a, the thermal and electrical properties of the molten glass (density, thermal conductivity, specific heat, viscosity, flow). Moreover, in the mathematical model, using the characteristics of the platinum alloy constituting the tube main body 102a, the fields expressing the electric field, temperature field, and flow field equations are discretized by means of the finite element method, finite volume method, or finite difference method, and numerical analysis is performed. The temperature distribution of the pipe main body 102a can be obtained. These tools, as mathematical models, can use custom software or commercially available software. Examples of commercially available software packages include AUTOCAD and SOLIDWORKS as 3-D and CAD software, GAMBIT, FEMAP, KSWAD, and ICEMCFD as mesh software, and FIDAP and FLUENT as software for calculating Joule heating heat conduction and glass flow. etc., CFD-POST, ENSGHT, etc. are listed as follow-up tools for calculation results. the

(2) Outline of glass plate manufacturing method

(2-1) Raw material of glass

The method for manufacturing a glass plate according to the present invention can be applied to the manufacture of various glass plates, and is particularly suitable for the manufacture of glass substrates for flat-panel displays such as liquid crystal display devices, organic EL displays, and plasma display devices, or cover glass covers that cover display parts. . the

To manufacture a glass plate according to the utility model, the glass raw material must first be prepared so as to achieve the desired glass composition. For example, when manufacturing a glass substrate for a flat-panel display, it is preferable to prepare raw materials so as to have the following components. the

(a) SiO ₂ : 50 to 70% by mass

(b) B ₂ O ₃ : 5 to 18% by mass

(c) Al ₂ O ₃ : 10 to 25% by mass

(d) MgO: 0 to 10% by mass

(e) CaO: 0 to 20% by mass

(f) SrO: 0 to 20% by mass

(o) BaO: 0 to 10% by mass

(p) RO: 5 to 20% by mass (however, R is at least one selected from Mg, Ca, Sr, and Ba)

(q) R' ₂ O: more than 0.10% by mass and less than 2.0% by mass (however, R' is at least one selected from Li, Na, and K)

(r) At least one metal oxide selected from tin oxide, iron oxide, ceria, and the like, in a total of 0.05 to 1.5% by mass. the

In addition, (q) R' ₂ O does not have to be contained necessarily, and may not be contained. In this case, the alkali-free glass substantially does not contain R' ₂ O, and the possibility of R' ₂ O flowing out from the glass plate and destroying the TFT can be reduced. In addition, it is necessary to make it contain 0.10 mass % to 2.0 mass % of (q) R' ₂ O to become a slightly alkali glass, which can suppress the degradation of TFT characteristics or the thermal expansion of the glass within the specified range, and increase the alkalinity of the glass. It is easy to oxidize metals with changing valence states and improve clarity. Moreover, the specific resistance of the glass can be reduced, which is suitable for performing an electric melting process in the melting tank 101 .

For example, like non-alkali glass or slightly alkali glass, the glass whose temperature reaches 1500-1750°C in logη=2.5, in order to make it have sufficient bubble buoyancy speed in the clarification tank 102, for example, it is necessary to reduce the temperature of the molten glass to When it becomes high temperature 1620 degreeC or more, the volatilization amount of the platinum or platinum alloy which comprises the clarification tank 102 will increase. That is, because the glass with a temperature of 1500-1750°C in logη=2.5 is easy to increase the volatilization of platinum or platinum alloy, it is suitable for the present invention, and the glass with a temperature of 1530-1750°C in logη=2.5 is more suitable. Glasses with a temperature of 1550°C to 1750°C in logη=2.5 are more suitable, and glasses with a temperature of 1570°C to 1750°C in logη=2.5 are more suitable. the

In addition, in recent years, in order to further realize high-definition, flat-panel displays using P-Si (low-temperature polysilicon) TFTs or oxide semiconductors instead of α-Si TFTs are required. Here, in the formation process of P-Si (low temperature polysilicon) TFT or oxide semiconductor, there is a heat treatment process at a higher temperature than that of α-Si·TFT formation process. Therefore, glass plates made of P-Si (low temperature polysilicon) TFTs or oxide semiconductors are required to have a small thermal shrinkage rate. In order to reduce the heat shrinkage rate, it is best to increase the strain point of the glass, but glass with a high strain point tends to have a high viscosity (high temperature viscosity) at high temperature. Therefore, in the clarification tank 102, in order to attain the viscosity suitable for clarifying molten glass, it is necessary to raise the temperature of molten glass further. For this reason, it is necessary to further increase the temperature of the clarification tank 102, and oxidation or volatilization of the platinum or platinum alloy constituting the clarification tank 102 tends to occur. That is, the present invention is applicable to a glass plate for a P-Si·TFT mounted display. Furthermore, the present invention is also applicable to the manufacture of a glass plate for an oxide semiconductor mounted display. the

That is, the present invention is suitable for, for example, the manufacture of a glass plate whose strain point exceeds 655° C. and whose temperature exceeds 1600° C. in logη=2. In particular, the utility model is suitable for glass plates with a strain point exceeding 675°C, more suitable for glass plates with a strain point exceeding 680°C, especially for glass plates with a strain point exceeding 690°C, wherein the glass plate with a strain point exceeding 675°C Boards are suitable for P-Si (low temperature polysilicon) TFT or oxide semiconductor. the

As a component of the glass plate whose strain point exceeds 675 degreeC, the glass plate containing the following components is shown by mass %, for example. the

SiO ₂ : 52 to 78% by mass, Al ₂ O ₃ : 3 to 25% by mass, B ₂ O ₃ : 3 to 15% by mass, RO (However, RO is the combined amount of MgO, CaO, SrO, and BaO): 3 -20% by mass, a glass plate having a mass ratio (SiO ₂ +Al ₂ O ₃ )/B ₂ O ₃ in the range of 7 to 20. Furthermore, in order to further increase the strain point, it is preferable that the mass ratio (SiO ₂ +Al ₂ O ₃ )/RO exceeds 7.5. In addition, in order to increase the strain point, the β-OH value is preferably 0.1 to 0.3 [mm-1]. On the other hand, to prevent the current from flowing to the melting tank 101 instead of the glass during melting, the mass % of R ₂ O (however, R ₂ O is the compounded amount of Li ₂ O, Na ₂ O and K ₂ O) is 0.01. ~0.8, the specific resistance of the glass is reduced. Or, in order to reduce the specific resistance of glass, _it is preferable that the mass % of _Fe2O3 is 0.01-1. In addition, in order to prevent an increase in the crystallization temperature while realizing a high strain point, it is preferable that CaO/RO exceeds 0.65. By changing the crystallization temperature to 1250° C. or lower, the overflow down-draw method can be applied. Furthermore, in consideration of application to mobile devices, from the viewpoint of weight reduction, the total content of SrO and BaO is preferably less than 0 to 2% by mass.

Moreover, it is preferable that the above-mentioned glass substrate for a flat display does not contain arsenic substantially, and it is most preferable that it does not contain arsenic and antimony substantially. That is, these substances are contained immediately, but only as impurities. Specifically, these substances contain oxides such as As ₂ O ₃ and Sb ₂ O ₃ , and it is preferable that the mass % is less than 0.1.

In addition to the above-mentioned components, the glass of the present invention may contain various other oxides in order to adjust various physical, melting, clarifying and forming properties of the glass. Examples of such other oxides are not limited to those shown below, but include SnO ₂ , TiO ₂ , MnO, Nb ₂ O ₅ , MoO ₃ , Ta ₂ O ₅ , WO ₃ , YaO ₃ and La ₂ O ₃ . Here, since glass substrates for flat-panel displays such as liquid crystal displays and organic EL displays have particularly strict requirements on foam, it is preferable to contain at least SnO ₂ which has a large clarification effect among the above-mentioned oxides.

Nitrate or carbonate can be used as the supply source of RO in (p) among (a) to (r) above. Moreover, in order to improve the oxidizing property of a molten glass, it is preferable to use carbonate in the ratio suitable for a process as a supply source of RO. the

The glass plate manufactured according to this example can be manufactured continuously, unlike the method in which a certain amount of glass raw material is put into a melting furnace for mass production. The glass plate suitable for the manufacturing method of the present invention can have any thickness and width. the

(2-2) Overview of glass manufacturing process

A glass plate manufacturing method related to an embodiment of the present invention includes a series of processes shown in the flow chart of FIG. 1 and uses a glass plate production line shown in FIG. 2 . the

The glass raw materials blended into the above components are first melted in the melting process (step S101 ). Raw materials are charged into the melting tank 101 and heated to a predetermined temperature. For example, in the case of a glass substrate for a flat panel display having the above composition, the predetermined temperature is preferably more than 1550°C. The heated raw materials melt and form molten glass. The molten glass is sent to the clarification tank 102 which performs the next clarification process (step S102) through the 1st conveyance pipe 105a. the

In the following clarification process (step S102 ), the molten glass is clarified. Specifically, when the molten glass is heated to a predetermined temperature in the clarification tank 102, the gas components contained in the molten glass form bubbles, or are gasified and discharged out of the molten glass. For example, in the case of a glass substrate for a flat panel display having the above composition, the predetermined temperature is preferably 1610°C to 1700°C. The clarified molten glass is sent to the stirring tank 103 which performs the next process, ie, the homogenization process (step S103), through the 2nd conveyance pipe 105b. the

In the following homogenization process (step S103 ), the molten glass is homogenized. Specifically, molten glass is homogenized by being stirred by an impeller (not shown) included in the stirring tank 103 in the stirring tank 103 . The molten glass sent to the stirring tank 103 is heated to a predetermined temperature. For example, in the case of a glass substrate for a flat panel display having the above composition, the predetermined temperature is preferably 1440°C to 1500°C. The homogenized molten glass is sent from the stirring tank 103 to the third delivery pipe 105c. the

In the next supply process (step S104 ), the molten glass is heated to a temperature suitable for forming in the third delivery pipe 105 c, and is sent to the forming device 104 for performing the next forming process (step S105 ). For example, in the case of a glass substrate for a flat panel display having the above-mentioned composition, the optimum temperature for molding is about 1200°C. In particular, when the overflow down-draw method is used in the forming process, the temperature in the most downstream region of the third delivery pipe 105c is preferably 1300-1200°C. the

In the following forming process (step S105 ), the molten glass is formed into sheet glass. In this embodiment, the molten glass is continuously formed into ribbons by the overflow down-draw method. Formed ribbons of glass that are cut into panes of glass. The overflow down-draw method is a well-recognized method, for example, as described in US Pat. No. 3,338,696 specification, into a forming body, and the overflowing molten glass slides down each outer surface of the forming body, downwards at the bottom of the forming body A method of extending the confluence into a ribbon of glass. the

(3) Specific examples

As shown below, if the glass plate manufacturing method related to this embodiment is actually used, for example, the breakage of a tubular refractory metal device (for example, a clarification tank) can be effectively suppressed, and the long service life can be extended, wherein the The tubular refractory metal fitting is constructed of platinum or platinum alloy and extends lengthwise. the

First, the raw materials are mixed so that the manufacturing components are SiO ₂ : 61% by mass, B ₂ O ₃ : 12% by mass, Al ₂ O ₃ : 18% by mass, CaO: 5.8% by mass, SrO: 3% by mass, Fe ₂ O ₃ : 0.1% by mass, SnO ₂ : glass of 0.1% by mass. Next, raw materials are put into the melting tank 101, and a glass plate is produced by performing a series of processes related to the glass plate manufacturing method of the present invention using the glass plate production line 100. That is, in the melting tank 101, the glass raw material is heated to about 1580° C. to be melted to form a molten glass, and the molten glass is sent to the clarification tank 102 through the first delivery pipe made of platinum and rhodium alloy, and the clarification tank 102 The molten glass is heated to about 1700°C internally. At this time, the pipe main body 102a is made of platinum or rhodium alloy, has a total length of 4000mm, a diameter of about 350mm, and a thickness of 1mm, and is between the first power supply device 201a and the second power supply device 201b, spanning from the second power supply device 201b about The entire circumference of a total length of 150 mm from a position of 300 mm to a position of approximately 450 mm has the above-mentioned thick portion 102 b having a thickness of 1.2 mm. After being stirred in the stirring tank 103, the clarified molten glass is sent to the forming device 104 through the third conveying pipe 105c, and the glass is processed into a plate shape by the overflow down-draw method.

Compared with when the above-mentioned glass plate was produced by using the clarification tank without the thick wall portion 102b, the clarification tank was damaged within one and a half years. As mentioned above, the clarification tank 102 was not damaged. the

(4) Features

The glass plate manufacturing method related to the present invention is a glass plate manufacturing method comprising a process of pouring molten glass into a device made of a tubular refractory metal extending in the longitudinal direction, characterized in that the device made of a refractory metal is at least insufficient in refractory The melting point of the metal, and part of the part in contact with the molten glass lower than the melting point of 150°C or more, has a thick wall part 102b thicker than other parts, wherein the refractory metal is platinum or platinum constituting a device made of refractory metal alloy. Or, it is characterized in that the electric resistance of the part (excluding the whole area|region of the clarification tank 102) including at least the region where the temperature of molten glass reaches the highest in a clarification tank is smaller than other parts. According to this configuration, the temperature rise of the thick portion 102b can be suppressed. Moreover, only increasing the strength of the thickness portion makes it difficult to perforate even if the refractory metal is oxidized or volatilized, increasing the durability of the device made of refractory metal. Therefore, according to the manufacturing method of the glass plate concerning this invention, for example, the lifetime of the apparatus made of refractory metal, ie, the clarification tank 102 can be extended effectively like the above-mentioned embodiment. In addition, as a method of reducing the resistance, not only the thick wall portion 102b is provided, but also the material of the position (except the entire area of the clarification tank 102) at least including the temperature of the molten glass in the clarification tank 102, It becomes a material with lower resistance than other parts. the

Symbol Description

100 glass plate production line

101 melting tank

102 clarifier tank (device made of refractory metal)

102a Pipe (clarifier) body

102b thick wall part

Prior art literature

Patent Documents

Patent Document 1: Special Publication No. 2010-502550

Claims (11)

1. A settling tank made of refractory metal and used for the manufacture of glass plates, characterized in that: The clarification tank is made of platinum or platinum alloy, and the tank of the clarification tank has a space for accommodating the gas discharged through degassing, The said clarification tank contains at least a thick part which has a thick wall thicker than other parts, and this thick part is located in the part where the temperature of molten glass reaches the highest range. the 2. The settling tank according to claim 1, characterized in that: The clarification tank has a plurality of power supply devices arranged along the flow direction of the molten glass, The region where the temperature of the molten glass reaches the highest in the clarification tank is located in the upstream side region of the flow direction center of the molten glass in the clarification tank. the 3. The clarifier according to claim 1, characterized in that: The length of the said thick part is 1/25 - 1/2 of the full length of the said clarification tank. the 4. The clarifier according to claim 2, characterized in that: The clarification tank includes a pipe main body and at least three power supply devices arranged at both ends and the middle of the pipe main body, The thick-walled portion spans at least half of the outer circumference of the pipe main body, and is at least provided on the top of the pipe main body. the 5. The clarifier according to claim 4, characterized in that: The entire outer periphery of the said clarification tank has the said thick part. the 6. The clarification tank according to any one of claims 1 to 5, characterized in that: The outer peripheral surface of the clarification tank is provided with a refractory oxide spray coating. the 7. A device made of platinum or platinum alloy for manufacturing glass plates, characterized in that: said device made of platinum or platinum alloy has a tubular shape elongated toward the length direction, The device made of platinum or platinum alloy has a thick wall thicker than other parts at least in part of the part which is less than the melting point of the platinum or platinum alloy and which is in contact with molten glass whose melting point is 150°C or higher department. the 8. The device made of platinum or platinum alloy according to claim 7, characterized in that: The entire periphery of the device made of platinum or platinum alloy has the thick-walled portion. the 9. The device made of platinum or platinum alloy according to claim 7 or 8, characterized in that: The outer peripheral surface of the device made of platinum or platinum alloy is provided with a refractory oxide spraying layer. the 10. A glass plate manufacturing device, characterized in that, comprising: Melting tank for melting glass raw materials to form molten glass; The first conveying pipe is used for conveying molten glass; A clarification tank as claimed in any one of claims 1 to 6, used to clarify the molten glass transported from the first delivery pipe; The second conveying pipe is used to convey the clarified molten glass; The stirring tank is used to stir the clarified molten glass transported from the second conveying pipe to homogenize the molten glass; The third conveying pipe is used to convey the homogenized molten glass, and The molding device is used to shape the homogenized molten glass delivered from the third delivery pipe. the 11. A glass plate manufacturing device, characterized in that, comprising: Melting tank for melting glass raw materials to form molten glass; The first conveying pipe is used for conveying molten glass; A device made of platinum or a platinum alloy as claimed in any one of claims 7 to 9 for clarifying molten glass transported from the first delivery pipe; The second conveying pipe is used to convey the clarified molten glass; The stirring tank is used to stir the clarified molten glass transported from the second conveying pipe to homogenize the molten glass; The third conveying pipe is used to convey the homogenized molten glass, and The molding device is used to shape the homogenized molten glass delivered from the third delivery pipe. the

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