KR20120028306A - Method for producing molten glass, vacuum degassing apparatus, and method for producing glass product - Google Patents

Abstract

Providing the molten glass manufacturing method by which the fall of the pressure reduction defoaming effect by the enlargement of a bubble layer was prevented, and the pressure reduction defoaming apparatus suitable for this molten glass manufacturing method.
A molten glass manufacturing method provided with the process of degassing a molten glass in a vacuum degassing tank, The molten glass manufacturing method of heating and supplying gas to the upper space of the molten glass which distributes the said vacuum degassing tank at a temperature of 500 degreeC or more.

Description

METHOD FOR PRODUCING MOLTEN GLASS, VACUUM DEGASSING APPARATUS, AND METHOD FOR PRODUCING GLASS PRODUCT}

This invention relates to the molten-glass manufacturing method provided with the process of vacuum-degassing a molten glass in a vacuum degassing tank, a vacuum degassing apparatus, and a manufacturing method of a glass article.

In order to improve the quality of the molded glass product conventionally, the clarification process which removes the bubble which generate | occur | produced in the molten glass before shape | molding the molten glass which melt | dissolved the raw material by the melting furnace with the shaping | molding apparatus is used.

In this clarification process, a molten glass is introduced into a reduced pressure atmosphere, the bubbles in the molten glass flow which continuously flow in this reduced pressure atmosphere are largely grown to raise bubbles contained in the molten glass, and the bubbles are blown off the molten glass surface to remove them. And the vacuum degassing | defoaming method discharged from a pressure reduction atmosphere after that is known.

In such a clarification process, when the bubble layer enlarges on the molten glass surface, the pressure reduction defoaming effect falls and there exists a possibility that a bubble may remain in the molten glass after a clarification process implementation. The pressure reduction defoaming effect here means the effect which raises the bubble contained in a molten glass by the above-mentioned action, and bubbles and removes a bubble from a molten glass surface.

Bubbles in the molten glass after the clarification step are difficult to remove, and may remain in the glass product to be produced and cause defects. In addition, with the enlargement of the bubble layer in a molten glass surface, the bubble layer which exists in the surface of a molten glass about 10 mm or less normally during pressure reduction defoaming implementation is 10 mm? The phenomenon which enlarges to several hundred mm is said.

When enlargement of a bubble layer further advances, what is called a dolby may arise. Dolby is a phenomenon in which bubbles that reach the glass surface that normally disappear with time are stably present for a long time by forming a layer without breaking, resulting in an increase in the molten glass interface. Even when a dolby generate | occur | produces, a pressure reduction defoaming effect falls and it is a problem because a bubble may remain in the molten glass after a clarification process implementation.

The applicants of this application propose the patent document 1, 2 to the molten-glass manufacturing method which can prevent the enlargement of the bubble layer in the molten glass surface, or the fall of the pressure reduction defoaming effect by a dolby, and the vacuum degassing apparatus of molten glass. .

The molten glass manufacturing method of patent document 1 is equipped with the process of degassing a molten glass under reduced pressure by making water vapor concentration into 60 mol% or less by introducing low moisture gas into the atmospheric gas in a pressure reduction degassing tank. Thereby, enlargement of a bubble layer, dolby, and the fall of the pressure reduction defoaming effect by them on the molten glass surface are prevented.

The prevention of dolby can prevent adhesion of adhering matters to the wall or ceiling of the pressure reducing degassing tank in the molten glass which has been dolby, so that defect formation of the glass product due to the drop can be prevented and the quality can be improved.

Moreover, since moisture is reduced in the atmosphere which encourages volatilization of a specific component (boron etc.), it exhibits the effect that volatilization of the specific component (boron etc.) in a molten glass can be suppressed. And when manufacturing a glass platen as a glass product, the deterioration of the flatness can be suppressed.

The vacuum degassing apparatus of the molten glass of patent document 1 has the low moisture gas introduction means which introduces a low moisture gas into the upper space in a pressure reduction degassing tank.

On the other hand, in the molten glass manufacturing method of patent document 2, a gas flow is formed above the molten glass which distributes a pressure reduction degassing tank, and the retention of the gas component from a molten glass is eliminated, and the bubble layer is enlarged and pressure reduction by it It prevents the degassing effect from falling.

Moreover, the fall of the vacuum degassing | defoaming effect by the cause other than enlargement of a bubble layer is also prevented by eliminating retention of the gas component from a molten glass.

The vacuum degassing apparatus of the molten glass of patent document 2 is a gas introduction means which introduces gas into the upper space in a pressure reduction degassing tank, and the upper space in order to form a gas flow above the molten glass which distributes a pressure reduction degassing tank. It has a gas flow formation means which consists of a gas derivation means which draws out gas from the gas.

International publication 2008-029649 brochure International publication 2008-093580 brochure

Depending on the use of the glass article, there is also a very strict demand for bubble quality, ie the number of bubble defects present in the glass article. As a specific example of such a glass product, the glass substrate for flat panel displays (FPD), optical glass, etc. are mentioned.

In order to manufacture glass products with extremely high demands on such bubble quality, it is required to further prevent the enlargement of the bubble layer on the glass surface and the deterioration of the pressure reduction defoaming effect thereby.

MEANS TO SOLVE THE PROBLEM In order to solve the problem of said prior art, this invention provides the molten glass manufacturing method which was excellent in the pressure reduction defoaming effect, More specifically, the molten glass manufacturing method in which the fall of the pressure reduction defoaming effect by the enlargement of a bubble layer was prevented. For the purpose of

Moreover, an object of this invention is to provide the vacuum degassing apparatus suitable for the molten-glass manufacturing method of this invention.

It is also an object of the present invention to provide a method for producing a glass product having high bubble quality, that is, very few bubble defects.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to achieve the said objective, in the molten-glass manufacturing method of patent document 1, 2, it is a vacuum degassing effect to supply gas above the molten glass which distributes the inside of a pressure reduction degassing tank. It has been found that there may be times when it is difficult to exercise effectively.

 That is, in the molten glass manufacturing methods of patent documents 1 and 2, although the gas supplied above the molten glass which distribute | circulates the inside of a pressure reduction degassing tank warms by the atmospheric gas of a pressure reduction degassing tank, or the radiant heat from the molten glass surface, The temperature is much lower than the surface temperature of the molten glass flowing in the vacuum degassing tank, and is usually about room temperature. By supplying such a low temperature gas, the temperature of the molten glass surface which flows through the inside of a pressure reduction degassing tank locally falls. Since the breaking speed on the molten glass surface depends on the temperature of the molten glass surface, when the surface temperature of the molten glass falls, the breaking speed on the surface will fall, and the pressure reduction defoaming effect will be performed with respect to the site | part where the surface temperature fell. There is a risk of deterioration.

The decrease in the surface temperature of the molten glass due to the supply of low-temperature gas, and the decrease in the pressure reduction defoaming effect thereof, are local, but may be a problem for glass products having a strict demand for bubble quality such as glass substrates for FPD. .

This invention was made based on the knowledge of the inventors mentioned above, It is a molten-glass manufacturing method provided with the process of degassing a molten glass under reduced pressure in a vacuum degassing tank, Comprising: In the upper space of the molten glass which distributes the said vacuum degassing tank. The molten glass manufacturing method which heats and supplies a gas to the temperature of 500 degreeC or more is provided.

Moreover, this invention is formed in the said pressure reduction housing which pressure-reduced pressure reduction suction, the pressure reduction degassing tank formed in the said pressure reduction housing, and performs the pressure reduction defoaming of molten glass, and the said pressure reduction defoaming tank, The molten glass before pressure reduction defoaming said As a pressure reduction defoaming apparatus of the molten glass which has the introduction means introduce | transduced into a pressure reduction degassing tank, and is formed in communication with the said pressure reduction degassing tank, and the derivation means which derives the molten glass after pressure reduction defoaming from the said pressure reduction defoaming tank,

It provides a vacuum degassing apparatus of the molten glass further including the gas introduction means which introduces gas into the upper space inside the said pressure reduction degassing tank, and the heating means which heats the gas introduce | transduced into the said upper space.

Moreover, in the vacuum degassing apparatus of the molten glass of this invention, the said gas introduction means consists of a hollow tube, and the said heating means is formed along the pipeline which passes inside the said pressure reduction housing of the said hollow tube.

Moreover, in the vacuum degassing apparatus of the molten glass of this invention, the said heating means is formed in the inside of the pipeline of the said hollow tube.

Moreover, the vacuum degassing apparatus of the molten glass of this invention further has a water vapor concentration measuring means which measures the vapor concentration of the atmospheric gas of the said vacuum degassing tank.

Moreover, in the vacuum degassing apparatus of the molten glass of this invention, the said gas introduction means is formed in the ceiling part or side surface of the vacuum degassing tank which forms the upper space on the molten glass inside a pressure reduction degassing tank.

Moreover, this invention provides the manufacturing method of the glassware provided with the raw material melting process and the shaping | molding process as the pressure reduction defoaming process by the pressure reduction defoaming apparatus of the said molten glass, and the front and back processes of the pressure reduction defoaming process.

In the molten glass manufacturing method of this invention, since the gas heated at 500 degreeC or more is supplied to the upper space of the molten glass which distributes a pressure reduction degassing tank, the fall of the molten glass surface temperature by supply of gas, and the pressure reduction defoaming effect to it It is possible to prevent the enlargement of the bubble layer and the deterioration of the pressure reduction defoaming effect thereby by not causing a decrease in the number of bubbles.

Moreover, in the molten glass manufacturing method of this invention, since the fall of the molten glass surface temperature by supply of gas, and the fall of the vacuum degassing | defoaming effect are prevented to it, it supplies to the upper space of the molten glass which distributes a vacuum degassing tank. The supply of gas can be increased. Thereby, the effect which prevents enlargement of a bubble layer, and the fall of the pressure reduction defoaming effect by it can further be improved.

Since the molten glass manufacturing method and glass product manufacturing method of this invention can obtain the molten glass and glass goods which are extremely excellent in bubble quality by the said effect, it is preferable as a manufacturing method of glass substrates for FPD, optical glass, etc. Do.

1: is sectional drawing which shows the example of 1 structure of the vacuum degassing apparatus of this invention.
FIG. 2: is a figure which showed the flow direction of the gas flow formed above the molten glass G which distribute | circulates the vacuum degassing tank 12 shown in FIG.

Hereinafter, the present invention will be described with reference to the drawings.

1: is sectional drawing which shows the example of 1 structure of the vacuum degassing apparatus of this invention. In the vacuum degassing apparatus 10 shown in FIG. 1, the cylindrical pressure reduction degassing tank 12 is arrange | positioned in the pressure reduction housing 11 so that the long axis may orientate in a horizontal direction. The upstream lower surface of the pressure reduction degassing tank 12 is equipped with the riser tube 13 oriented in a vertical direction, and the downcoming tube 14 is attached to the downstream lower surface. In addition, with the upstream and downstream of the pressure reduction degassing tank 12, the pressure reduction degassing tank 12 is circulated, ie, in the flow direction of the molten glass G which flows in the pressure reduction degassing tank 12 in a horizontal direction. It means an upstream side and a downstream side. A part of the rising pipe 13 and the falling pipe 14 is located in the pressure reduction housing 11.

As shown in FIG. 1, the riser 13 communicates with the vacuum degassing tank 12, and is an introduction means for introducing the molten glass G from the melting tank 200 into the vacuum degassing tank 12. For this reason, the lower end part of the riser 13 is fitted in the opening end of the upstream pit 220, and is immersed in the molten glass G in this upstream pit 220. As shown in FIG.

The downcomer 14 communicates with the vacuum degassing tank 12, and is a derivation means for lowering the molten glass G after the vacuum degassing from the vacuum degassing tank 12 to lead to a treatment tank (not shown) in a later step. . For this reason, the lower end part of the downcomer 14 is fitted in the opening end of the downstream pit 240, and is immersed in the molten glass G in this downstream pit 240. As shown in FIG.

In the pressure reduction housing 11, the heat insulating material 18, such as a heat insulation brick which heat-insulates and covers these, is arrange | positioned and formed around the pressure reduction degassing tank 12, the rising pipe 13, and the downfalling pipe 14. As shown in FIG.

In the vacuum degassing apparatus 10 shown in FIG. 1, since the vacuum degassing tank 12, the rising pipe 13, and the downpipe 14 are conduits of molten glass G, they are excellent in heat resistance and corrosion resistance with respect to molten glass. It is manufactured using materials. For example, it is a hollow tube made of platinum or a platinum alloy. Specific examples of the platinum alloy include a platinum-gold alloy and a platinum-rhodium alloy. Another example is a hollow tube made of a ceramic nonmetal inorganic material, that is, a dense refractory material. Specific examples of the dense refractories include, for example, electroforming refractories such as alumina based electroforming refractory, zirconia based electroforming refractory, alumina-zirconia-silica based electroforming refractory, and dense alumina based refractory, dense zirconia Dense calcined refractory materials, such as a silica type refractory material and a dense alumina zirconia-silica type refractory material, are mentioned. The pressure reduction housing 11 which accommodates the pressure reduction degassing tank 12 and which accommodates a part of the uprising pipe 13 and the downfalling pipe 14 is made of metal, for example, stainless steel.

In the vacuum degassing apparatus 10 of this invention shown in FIG. 1, the window 15, 16 for monitoring the inside of the vacuum degassing tank 12 is provided in the upstream and downstream of the ceiling part of the vacuum degassing tank 12. FIG. It is. The windows 15 and 16 are hollow tubes made of platinum, platinum alloys, or dense refractory, one end of which is in communication with the upstream and downstream sides of the ceiling of the vacuum degassing tank 12 and the other end thereof. Penetrates the wall surface of the pressure reduction housing 11 and is located outside the pressure reduction housing 11.

In the window 15 formed on the upstream side of the vacuum degassing tank 12, a hollow tube 17 made of platinum or platinum alloy, or ceramic containing alumina, zirconia, or the like is inserted. The hollow tube 17 is gas introduction means which introduces the gas 100 into the upper space inside the pressure reduction degassing tank 12.

In addition, the upper space inside the pressure reduction degassing tank 12 refers to the space part above the molten glass G which distributes the pressure reduction degassing tank 12. In the pressure reduction degassing tank 12, the front-end | tip of the hollow tube 17 is located above molten glass G. As shown in FIG.

For example, the window 16 formed in the downstream side of the pressure reduction degassing tank 12 is connected to pressure reduction means (not shown), such as a pump, and the atmosphere gas of the said upper space of the pressure reduction housing 11 is carried out. By discharging to the outside, the inside of the pressure reduction degassing tank 12 can be pressure-reduced.

Although not shown, a heating means (for example, a heater) for heating the gas 100 introduced into the upper space inside the vacuum degassing tank 12 is formed inside the hollow tube 17. In addition, when using a heater as a heating means, the heat generation method is not specifically limited, Various heat generation methods, such as the method of heat-generating an electricity supply body, can be used.

The vacuum degassing apparatus of this invention has the gas introduction means which introduces a gas into the upper space inside a pressure reduction degassing tank, and the heating means which heats the gas introduce | transduced into the upper space, The upper part of the molten glass which distributes a pressure reduction degassing tank The heated gas can be supplied to the space.

In addition, it describes in the description about the molten-glass manufacturing method of this invention mentioned later about the kind of gas introduce | transduced from a gas introduction means, and the temperature of the gas after heating.

The gas introduction means in the vacuum degassing apparatus of this invention is not limited to the aspect shown in FIG. 1 as long as gas can be introduced into the upper space inside a vacuum degassing tank.

For example, in the vacuum degassing apparatus 10 shown in FIG. 1, although the hollow tube 17 of the straight end faced downward is shown, it is not limited to this, You may select suitably the shape of a hollow tube. For example, in order to guide the gas 100 introduced into the upper space inside the vacuum degassing tank 12 in the downstream direction, a hollow tube whose tip is curved in the downstream direction may be used. Moreover, you may provide a gas introduction means in the side surface instead of the upper direction of a pressure reduction degassing tank.

In addition, in the vacuum degassing apparatus 10 shown in FIG. 1, although the hollow tube 17 is inserted in the window 15 formed in the upstream, the hollow tube 17 which is a gas introduction means in the window 16 formed in the downstream side. ) May be inserted. In addition, the window 15 or the window 16 itself may be used as the gas introduction means without using the hollow tube 17.

However, considering that the heated gas is supplied to the upper space of the molten glass G through which the vacuum degassing tank 12 flows, the hollow tube 17 inserted into the window 15 or the window 16 is gas. It is preferable to use it as an introduction means, because the heated gas does not become cold before it is supplied to the upper space of the molten glass G. Moreover, a pressure reduction degassing tank during the action which prevents the enlargement of the bubble layer of the molten glass surface by introducing gas heated to the upper space of the molten glass which distributes the pressure reduction degassing tank mentioned later, and the fall of the pressure reduction defoaming effect by it. When exerting the effect | action by forming a gas flow above the molten glass which distribute | circulates, it is preferable to use the hollow tube 17 inserted in the window 15 or the window 16 as gas introduction means.

Moreover, when the bubble layer of the molten glass surface is easy to occur in the upstream of a pressure reduction degassing tank, it is inserted in the window 15 formed in the upstream of the pressure reduction degassing tank 12, or the window 15 inserted in it. It is preferable to use the hollow tube 17 as a gas introduction means.

In addition, in the above, the window 15, 16 formed in the ceiling part of the pressure reduction degassing tank 12, or the hollow tube inserted in the window 15, 16 for the purpose of monitoring the inside of the pressure reduction degassing tank 12 ( Although 17) is used as a gas introduction means, you may provide gas introduction means other than these sites.

For example, a hollow tube structure similar to the windows 15 and 16 is formed at a portion other than the ceiling of the vacuum degassing tank, for example, an upstream end surface, a downstream end surface, or a side surface of the vacuum degassing tank, and the hollow tube You may use a structure as a gas introduction means.

Moreover, in the vacuum degassing apparatus 10 shown in FIG. 1, although the windows 15 and 16 for monitoring the inside of the pressure reduction degassing tank 12 are formed in the upstream and downstream of the ceiling part of the pressure reduction degassing tank 12, In the ceiling of the vacuum degassing tank 12, a window for monitoring the inside of the vacuum degassing tank 12 may be formed at a portion (for example, an intermediate portion) other than the upstream side and the downstream side, or the window or the same. The hollow tube inserted into the window may be used as the gas introduction means.

Moreover, although one gas introduction means is formed in the vacuum degassing apparatus 10 shown in FIG. 1, the number of the gas introduction means in the vacuum degassing apparatus of this invention is not specifically limited, Plural number may be sufficient as it.

For example, in the vacuum degassing apparatus 10 shown in FIG. 1, in addition to the hollow tube 17 inserted in the window 15 of an upstream, a hollow tube is also inserted in the downstream window 16, and gas You may use as an introduction means.

In addition, the gas introduction means includes a mechanism (for example, a gas flow control valve) for controlling the gas introduction amount, a valve mechanism for stopping gas introduction as necessary, and then restarting gas introduction (for example, Solenoid valve) may be formed.

The heating means in the vacuum degassing apparatus of this invention is not limited to said aspect as long as the gas introduce | transduces the gas introduce | transduced into the upper space inside a pressure reduction degassing tank.

For example, in the above, although it is described that the heating means for heating the gas 100 is formed in the hollow tube 17 which is a gas introduction means, a heating means is provided in the outer periphery of the hollow tube 17, You may also In this case, what is necessary is just to wind a heater as a heating means in the outer periphery of the hollow tube 17, for example.

Moreover, it is preferable to form a heating means along the pipe line of the hollow tube 17 in the pressure reduction housing 11. In this case, the temperature of the gas just before introducing into a vacuum degassing tank does not fall. Moreover, as for a heating means, it is more preferable to form in the inside of the channel of the hollow tube 17 which is a gas introduction means. In this case, the gas can be heated more efficiently. In addition, when the heating means is formed along the pipeline of the hollow tube, the continuous means is formed over the entire pipeline in the decompression housing 11, when the heating means is formed at regular intervals over the entire pipeline, or enters the vacuum degassing tank. It includes the case of forming in the immediately preceding area.

As described above, when the window 15 or the window 16 itself is used as the gas introduction means without using the hollow tube 17, the window 15 or the window 16 is provided with a heating means. You may form.

In addition, the heating means is not formed in the windows 15 and 16 or the hollow tube 17 inserted into the windows 15 and 16, but is inserted into the windows 15 and 16 or the windows 15 and 16. You may provide the heating means for heating beforehand the gas before supplying to the hollow tube 17. As a specific example of such a heating means formation, installation of a heating means to a gas supply source, such as a cylinder, and installation of a heating means to the gas supply piping upstream rather than the gas hollow pipe 17 are mentioned.

In addition to the said component, the vacuum degassing apparatus of this invention enlarges the bubble layer of the surface of a molten glass by introducing the gas heated to the upper space of the molten glass which distributes the vacuum degassing tank mentioned later, and pressure reduction by it You may have another component suitable for exhibiting the effect of preventing the fall of a defoaming effect.

For example, in order to exhibit the effect which prevents the enlargement of the bubble layer of the molten glass surface, and the fall of the pressure reduction defoaming effect by forming a gas flow above the molten glass which distributes a pressure reduction degassing tank, a pressure reduction degassing tank (12) In addition to the gas introduction means for introducing the gas 100 into the upper space therein, gas derivation means for deriving the gas from the upper space is required. Although it will mention later in detail, in the case of the vacuum degassing apparatus 10 shown in FIG. 1, the downstream window 16 can be used as gas derivation means.

Moreover, since gas flow is formed near the surface (liquid surface) of the molten glass G, you may form the baffle plate 19 for guide | inducing a gas flow below inside the ceiling part of the pressure reduction degassing tank 12. Moreover, as shown in FIG.

Moreover, when the water vapor concentration of the atmospheric gas of a vacuum degassing tank is 60 mol% or less, when it exhibits the effect which prevents the enlargement of the bubble layer of the molten glass surface, and the fall of the pressure reduction defoaming effect by it, the vapor of the atmospheric gas It is preferable that the water vapor concentration measuring means for measuring a density | concentration is formed, and it is preferable that a gas introduction means can control the gas introduction amount according to the water vapor concentration measured by the water vapor concentration measuring means.

As the vapor concentration measuring means, a commercial dew point meter may be used, and water contained in the atmospheric gas discharged from the vacuum degassing tank as described in Patent Literature 1 is precipitated, and the amount of the atmospheric gas is measured. It is also possible to estimate the water vapor concentration.

In the vacuum degassing apparatus of this invention, in order to depressurize the upper space in a pressure reduction degassing tank, a tank opening part is formed in the ceiling part of the pressure reduction degassing tank accommodated and installed in the pressure reduction housing, for example, A suction opening is formed in a ceiling part, the vacuum pump which makes the inside of a pressure reduction degassing tank into a pressure reduction is connected to the said suction opening, and the vacuum degassing of a molten glass is performed by operation of the said vacuum pump.

Moreover, as mentioned above, when gas introduction means is formed in the window 15 side upstream of the pressure reduction degassing tank 12, pressure reduction means, such as a vacuum pump, is connected to the window 16 side formed in the downstream side. In addition, the method of exhausting the atmospheric gas of the upper space of a pressure reduction degassing tank to the exterior of the pressure reduction housing 11, and depressurizing the inside of the pressure reduction degassing tank 12 may be employ | adopted. And when gas introduction means is formed in the window 16 side downstream of the pressure reduction degassing tank 12, pressure reduction means, such as a vacuum pump, is connected to the window 15 side formed in the upstream, You may employ | adopt the method which discharges the atmospheric gas of the upper space of a tank to the outside of the pressure reduction housing 11, and depressurizes the inside of the pressure reduction degassing tank 12.

The method and structure which pressure-reduces the inside of a pressure reduction degassing tank can adopt suitably the optimal method and structure according to the structure of a pressure reduction degassing apparatus.

The dimension of each component of the vacuum degassing apparatus 10 of this invention can be suitably selected as needed. The size of the vacuum degassing tank 12 is based on the shape of the vacuum degassing apparatus 12 and the vacuum degassing tank 12 used, regardless of whether the vacuum degassing tank 12 is a platinum agent, a platinum alloy, or a dense refractory agent. It can select accordingly. In the case of the cylindrical pressure reduction degassing tank 12 as shown in FIG. 1, an example of the dimension is as follows.

Length in horizontal direction: 1 20 m

? Inner diameter: 0.2 3 m (cross section)

When the pressure reduction degassing tank 12 is made of platinum or a platinum alloy, it is preferable that thickness is 4 mm or less, More preferably, it is 0.5? 1.2 mm.

The pressure reduction degassing tank is not limited to the thing of cylindrical shape of cross section circular, It may be a thing of the substantially cylindrical shape whose cross-sectional shape is elliptical or semi-circle shape, or a cylindrical shape of a cross section is rectangular.

The dimension of the riser 13 and the downtake 14 can be suitably selected according to the pressure reduction defoaming apparatus to be used, regardless of whether it is a platinum agent, a platinum alloy agent, or a dense refractory agent. For example, in the case of the vacuum degassing apparatus 10 shown in FIG. 1, an example of the dimension of the riser 13 and the downtake 14 is as follows.

? Inner diameter: 0.05 0.8 m, more preferably 0.1? 0.6 m

? Length: 0.2 6 m, more preferably 0.4? 4 m

In the case where the rising pipe 13 and the falling pipe 14 are made of platinum or a platinum alloy, the thickness is 0.4? It is preferable that it is 5 mm, More preferably, it is 0.8? 4 mm.

Next, the molten glass manufacturing method of this invention is demonstrated.

The molten glass manufacturing method of this invention is equipped with the process of degassing a molten glass in a vacuum degassing tank, and the gas for preventing the enlargement of the bubble layer of the molten glass surface in the upper space of the molten glass which distributes a vacuum degassing tank. It is supplied by heating to a temperature of 500 ℃ or more.

Here, the gas is hydrogen (H ₂₎ supplied to the upper space of the molten glass flowing in the vacuum degassing vessel, a nitrogen (N _2), oxygen (O _2), air, carbon monoxide (CO), carbon dioxide (CO _2), At least one gas selected from the group consisting of argon (Ar), helium (He), neon (Ne), krypton (Kr), xenon (Xe), hydrocarbon gas, fluorocarbon gas and ammonia (NH ₃ ) is preferred, , At least one gas selected from the group consisting of nitrogen, air, carbon dioxide, argon, helium, neon, krypton and xenon is more preferred, and at least one gas selected from the group consisting of nitrogen, air, carbon dioxide and argon is further preferred. desirable.

Moreover, it is preferable to use the gas selected from the said group as a gas supplied to the upper space of a molten glass, The effect which prevents the enlargement of the bubble layer of the surface of a molten glass mentioned later, and the fall of the pressure reduction defoaming effect by it is exhibited. This is because it is preferable to. More specifically, by forming a gas flow above the molten glass which distributes a pressure reduction degassing tank, it is preferable in order to exhibit the effect which prevents the enlargement of the bubble layer of the molten glass surface, and the fall of the pressure reduction defoaming effect by it. Because. Or by making the water vapor concentration of the atmospheric gas of a vacuum degassing tank into 60 mol% or less, it is preferable in order to exhibit the effect which prevents the enlargement of the bubble layer of the molten glass surface, and the fall of the pressure reduction defoaming effect by it, and This is because it does not adversely affect the molten glass, the glass product to be produced, and the glass manufacturing equipment, especially the vacuum degassing apparatus.

In addition, as it turns out that it is described as the at least 1 gas chosen from the said group, you may supply any 1 type of gas in the said group to the upper space of a molten glass, and 2 or more types of mixed gas may be supplied in the upper part of a molten glass. You may supply to space.

In addition, when the constituent material of a vacuum degassing tank is platinum or a platinum alloy, when air is used as a gas supplied to the upper space of the molten glass which distributes a vacuum degassing tank, oxygen concentration is gas which is lower than oxygen concentration in air. It is preferable. By using a gas whose oxygen concentration is lower than the oxygen concentration in the air, the oxidation of platinum, which is a constituent material of the vacuum degassing tank, is suppressed, the life of the vacuum degassing tank is increased, and the production of defects derived from platinum in glass products is suppressed. It is preferable because it can be done.

In order to acquire the said effect, it is more preferable that the oxygen concentration in gas is 15 volume% or less, It is more preferable that it is 10 volume% or less, It is more preferable that it is 5 volume% or less.

Moreover, it is preferable that the flow volume of the gas supplied to the upper space of a molten glass is 5 normal liters / minute or more from the point which can further improve the effect which prevents enlargement of a bubble layer, and the fall of the pressure reduction defoaming effect by it.

What is necessary is just to use the vacuum degassing apparatus of this invention demonstrated using FIG. 1, in order to heat and supply the at least 1 gas chosen from the said group to the upper space of the molten glass which distributes a pressure reduction degassing tank at 500 degreeC or more.

Since the molten glass manufacturing method of this invention supplies the gas heated at the temperature of 500 degreeC or more to the upper space of the molten glass which distribute | circulates a pressure reduction degassing tank, the fall of the temperature of the molten glass surface by supply of gas is drastically reduced. The fall of the pressure reduction defoaming effect by the fall of the temperature of the molten glass surface is also largely reduced.

Moreover, since the fall of the molten glass surface temperature by supply of gas, and the fall of the pressure reduction defoaming effect to it are prevented, the supply amount of the gas supplied to the upper space of the molten glass which distributes a pressure reduction degassing tank can be increased. Thereby, the effect which prevents enlargement of the bubble layer mentioned later and the fall of the pressure reduction defoaming effect by it can be improved further.

It is preferable to supply the gas heated at 550 degreeC or more to the upper space of the molten glass which distributes a vacuum degassing tank from the viewpoint of the said effect, and it is more preferable to supply the gas heated at 600 degreeC or more.

In the molten glass manufacturing method of this invention, the bubble layer of the molten glass surface is enlarged by introducing the gas heated at the temperature of 500 degreeC or more into the upper space of the molten glass which distributes a pressure reduction degassing tank, and the pressure reduction defoaming effect by it The effect of preventing the fall of is largely distinguished by the two actions described below. The molten glass manufacturing method of this invention may exert any one of these effects, and may exert both.

A 1st effect | action forms a gas flow above the molten glass which distribute | circulates a pressure reduction degassing tank, and enlarges the bubble layer of the molten glass surface by eliminating retention of the gas component from a molten glass, and pressure reduction defoaming by it It is prevention of fall of effect.

As mentioned above, the vacuum degassing | defoaming method raises the bubble contained in the molten glass by placing a molten glass in a reduced pressure atmosphere, and it foams and removes a bubble from the molten glass surface, but a bubble blows off from the molten glass surface When the gas component (henceforth "a gas component from a molten glass") which generate | occur | produced stays above the molten glass which distribute | circulates the inside of a pressure reduction degassing tank, in the atmosphere (upper space inside a pressure reduction degassing tank) above a molten glass, Since the partial pressure of the gas component from a molten glass becomes high, the bubble which floated on the molten glass surface becomes difficult to be bubbled, and the pressure reduction defoaming effect falls.

In addition, the gas components from the molten glass together is also different according to the glass composition, for example, there may be mentioned HCl, H ₂ SO _4, boric acid compound, such as HF.

As shown in FIG. 2, when the gas 100 is supplied from the hollow tube 17 which is a gas introduction means to the upper space of the molten glass G which distributes the pressure reduction degassing tank 12, the molten glass G Above, the gas flow g which flows from the upstream side to the downstream side of the pressure reduction degassing tank 12 is formed. The gas component from the molten glass is carried by the gas flow g, and is discharged to the outside from the window 16 serving as the gas derivation means. As a result, the retention of the gas component from the molten glass is eliminated. As the retention of the gas component from the molten glass is eliminated, the enlargement of the bubble layer on the surface of the molten glass and the deterioration of the reduced pressure defoaming effect thereby are prevented.

In addition, in FIG. 2, although the flow direction of the gas flow g and the flow direction of the molten glass G (namely, the flow direction of the molten glass shown by the arrow) are the same direction, the gas from a molten glass is formed by formation of a gas flow. As long as the retention of components can be eliminated, the flow direction of the gas flow g is not limited to this.

For example, the flow direction of the gas flow g and the flow direction of the molten glass G may be opposite directions. In this case, the gas 100 is supplied from the gas introduction means provided in the window 16 on the downstream side, and the gas flow which flows from the downstream side to the upstream side of the pressure reduction degassing tank 12 is formed. In this case, the upstream window 15 functions as gas derivation means.

Moreover, although the pressure reduction degassing tank 12 shown in FIG. 2 is a longitudinally long shape in the distribution direction of molten glass G, the length of the distribution direction of molten glass G is short, and width is short in a pressure reduction degassing tank. There is also a wide shape. In the case of such a vacuum degassing tank, you may form the gas flow of a perpendicular | vertical direction with respect to the width direction of a vacuum degassing tank, ie, the flow direction of molten glass G. FIG.

In addition, although the gas flow g of the same direction as the flow direction of the molten glass G is formed in the whole longitudinal direction of the pressure reduction degassing tank 12, in FIG. You may provide above. The some gas flow may be the same as the flow direction of molten glass G, or may be an opposite direction. In addition, the flow direction of the some gas flow may mutually be the same, or may be the opposite direction.

In addition, when forming the gas flow of a perpendicular | vertical direction with respect to the flow direction of molten glass G, or when forming a some gas flow above the molten glass G, the flow direction of the formed gas flow is considered. To arrange the gas introduction means and the gas derivation means.

However, considering that the bubble layer on the surface of the molten glass is likely to occur on the upstream side of the vacuum degassing tank, as shown in FIG. 2, the gas (from the hollow tube 17 inserted into the window 15 on the upstream side) may be separated from the gas ( It is preferable to supply 100) to form the gas flow g in the same direction as the flow direction of the molten glass G.

The 2nd action introduce | transduces the gas (low moisture gas) for preventing the enlargement of the bubble layer of the above-mentioned molten glass surface made into low moisture into the atmospheric gas of a pressure reduction degassing tank, and makes the water vapor concentration of this atmospheric gas 60 mol% or less. It is prevention of the enlargement of the bubble layer of the molten glass surface by making into, and the fall of the pressure reduction defoaming effect by it.

As described in Patent Literature 1, when the water vapor concentration of the atmospheric gas of the vacuum degassing tank exceeds a specific value, the bubble layer on the surface of the molten glass is enlarged, and other specific values higher than the specific value are exceeded. In this case, the enlargement of the bubble layer is further progressed and a dolby occurs. However, by introducing a low moisture gas into the atmosphere gas of the vacuum degassing tank and making the water vapor concentration of the atmosphere gas 60 mol% or less, the bubble layer on the surface of the molten glass is enlarged. And deterioration of the pressure reduction defoaming effect by it can be prevented. And of course, since the enlargement of the bubble layer of the molten glass surface is prevented, the fall of a Dolby and the pressure reduction defoaming effect by it can be prevented.

Here, low moisture gas refers to the gas whose water vapor concentration is lower than the atmospheric gas of a vacuum degassing tank. It is preferable that the water vapor concentration of low moisture gas is 60 mol% or less, It is more preferable that it is 50 mol% or less, It is more preferable that it is 40 mol% or less, It is more preferable that it is 30 mol% or less, It is more preferable that it is 25 mol% or less It is more preferable that it is 20 mol% or less, It is more preferable that it is 15 mol% or less, It is further more preferable that it is 10 mol% or less, It is especially preferable that it is 5 mol% or less.

In addition, all the gas supplied to the upper space of the molten glass which distributes a pressure reduction degassing tank can be supplied as a low moisture gas.

Moreover, since the bubble layer on the surface of a molten glass tends to become thinner as the water vapor concentration of the atmospheric gas of a vacuum degassing tank is low, it is preferable that it is 50 mol% or less, and it is more preferable that it is 40 mol% or less. Do. And since a bubble layer tends to become thinner if the water vapor concentration is 30 mol% or less, it is preferable.

Moreover, when the vapor concentration of the atmospheric gas is low, one bubble may shrink or break depending on the glass composition, and thus the bubble layer becomes thinner, which is preferable. Specifically, when the molten glass is borosilicate glass, if the water vapor concentration is 30 mol% or less, the bubbles tend to shrink significantly. In addition, the borosilicate glass here is the following composition in oxide conversion, for example.

Composition range: SiO ₂ : 50? 66, Al ₂ O ₃ : 10.5? 22, B ₂ O ₃ : 0? 12, MgO: 0? 8, CaO: 0? 14.5, SrO: 0? 24, BaO: 0? 13.5, MgO + CaO + SrO + BaO: 9? 29.5 (unit is mass%).

In addition, when the vapor concentration of the atmosphere gas is low, bubbles having a size that is regarded as a defect in glass products produced through vacuum degassing are less likely to remain, which is preferable. When the vapor concentration of the atmosphere gas is further lowered, the probability of a defect occurring in the glass product produced through vacuum degassing is further lowered, more preferably 25 mol% or less, more preferably 20 mol% or less, and 15 mol% It is more preferable that it is the following, It is more preferable that it is 10 mol% or less, It is further more preferable that it is 5 mol% or less.

Moreover, volatilization of the specific component (boron etc.) in a molten glass can be suppressed by making the water vapor concentration of this atmospheric gas into 60 mol% or less. By suppressing volatilization of components such as boron, it is possible to prevent composition fluctuations such as boron, and to suppress deterioration of flatness resulting from composition fluctuations.

Moreover, since volatilization, such as Cl, F, S, etc. which are easy to volatilize, can also be suppressed, the fluctuation | variation of the composition of these components can be prevented, and the deterioration of the flatness resulting from a composition fluctuation can be prevented. It can be suppressed.

It is thought that volatilization of these components, such as Cl, F, and S, is largely influenced by the moisture in atmosphere. For instance, F is an HF, S is considered to be volatilized as H ₂ SO _4. Therefore, it is thought that volatilization of the said component and the compositional fluctuation of the said component can be suppressed by making the water vapor concentration of the atmospheric gas into 60 mol% or less.

In the conventional method, since boron is volatilized from a molten glass, it was necessary to use more boron as a raw material. In addition, the amount of boron volatilized is different depending on conditions, and there also existed a problem that the fluctuation | variation of a glass composition occurs microscopically.

In the molten glass manufacturing method of this invention, volatilization of boron from a molten glass can be suppressed and these problems can be eliminated.

Also from this point, it can be said that the molten-glass manufacturing method of this invention can be used suitably when manufacturing borosilicate glass as well as normal glass.

In the molten glass manufacturing method of this invention, gas 100 is always supplied continuously to the upper space of the molten glass G which distributes the pressure reduction degassing tank 12 as long as it can exhibit said 1st or 2nd action. It is not necessary to do that.

In the case of a 1st effect | action, as long as the retention of the gas component from a molten glass can be eliminated, you may form a gas flow regularly during the implementation of reduced pressure defoaming, for example, 1 to 1? The gas flow may be formed for about 30 seconds. Therefore, the gas 100 can also be supplied to the upper space of the molten glass G which distribute | circulates the pressure reduction degassing tank 12 regularly.

Moreover, in the case of 2nd action | action, when the vapor concentration of the atmospheric gas of the vacuum degassing tank 12 is monitored during the execution of a vacuum degassing | defoaming, and there exists a possibility that the vapor concentration of the atmospheric gas may exceed 60 mol%. The gas 100 can also be supplied as a low moisture gas to the upper space of the molten glass G which distributes the pressure reduction degassing tank 12.

In the molten glass manufacturing method of this invention, the at least 1 gas chosen from the group of the gas supplied to the upper space of the molten glass which distributes the above-mentioned pressure reduction degassing tank to the upper space of the molten glass which distributes a pressure reduction degassing tank is made. It can carry out similarly to the conventional molten glass manufacturing method except the point which heats and supplies at the temperature of 500 degreeC or more. For example, at the time of performing vacuum degassing | defoaming, the inside of the pressure reduction degassing tank 12 is 1100 degreeC? 1600 ° C., especially 1150 ° C.? It is preferable to heat so that it may become a temperature range of 1450 degreeC. The inside of the vacuum degassing tank 12 is 38? It is preferable to depressurize to 460 mmHg (51 to 613 hPa), More preferably, it is 60? It is preferable to depressurize to 350 mmHg (80-467 hPa). Moreover, the flow volume of the molten glass G which distributes the pressure reduction degassing tank 12 is 1? It is preferable from the viewpoint of productivity that it is 2000 ton / day.

The manufacturing method of the glassware of this invention is equipped with the said vacuum degassing | defoaming process, and includes a raw material melting process and a shaping | molding process as a previous process and a post process. This raw material melting process may be a conventionally well-known thing, for example, and is a process of melting a raw material by heating to about 1400 degreeC or more according to the kind of glass, for example. The raw material to be used is not particularly limited as long as it is a raw material suitable for the glass to be produced. For example, raw materials obtained by combining conventionally known ones such as silica sand, boric acid, limestone, etc. according to the composition of the final glass product can be used, and the desired fining agent is contained. You may also Moreover, this molding process may be conventionally well-known, for example, For example, a float molding process, a roll out molding process, a fusion molding process, etc. are mentioned.

The molten glass and glass article manufactured by this invention are not restrict | limited in composition, as long as it is glass manufactured by the heat-melting method. Therefore, an alkali free glass may be sufficient and alkali glass, such as soda-lime silica type glass and alkali borosilicate glass represented by soda-lime glass, may be sufficient. The present invention is particularly suitable for producing alkali-free glass, and further, alkali-free glass for liquid crystal substrates.

Moreover, according to this invention, since the glass product which is extremely excellent in bubble quality, that is, very few bubble defects can be obtained, it is suitable as a manufacturing method of glass substrates for FPD, optical glass, etc.

Industrial availability

According to the molten glass manufacturing method of this invention, the fall of the molten glass surface temperature by supply of gas, and the fall of the pressure reduction degassing effect are not produced to it, but the enlargement of a bubble layer and the fall of the effect of the reduced pressure defoaming by it are prevented. Since it can be obtained, the molten glass and glass goods which are extremely excellent in bubble quality can be obtained, and it is preferable as a manufacturing method of the glass substrate for FPD, optical glass, etc.

In addition, all the content of the JP Patent application 2009-167512, the claim, drawing, and the abstract for which it applied on July 16, 2009 is referred here, and it introduces as an indication of this invention.

10: vacuum degassing apparatus
11: pressure reducing housing
12: vacuum degassing tank
13: riser
14 down pipe
15, 16: window
17: hollow tube (gas introduction means)
18: heat insulation
19: baffle
100 gas
200: melting tank
220: upstream feet
240: downstream feet
G: molten glass
g: gas flow

Claims (11)

A molten glass manufacturing method comprising a step of degassing a molten glass in a vacuum degassing tank, wherein the gas is heated and supplied to an upper space of a molten glass through which the vacuum degassing tank is circulated to be supplied at a temperature of 500 ° C or higher. Glass manufacturing method. The method of claim 1,
The gas supplied to the upper space of the molten glass flowing in the vacuum degassing vessel, the hydrogen (H _2), nitrogen (N _2), oxygen (O _2), air, carbon monoxide (CO), carbon dioxide (CO _2), argon (Ar), helium (He), neon (Ne), krypton (Kr), xenon (Xe), hydrocarbon-based gas, fluorocarbon-based gas and at least one gas selected from the group consisting of ammonia (NH ₃ ) Manufacturing method. The method according to claim 1 or 2,
The molten glass manufacturing method whose gas supplied to the upper space of the molten glass which distributes the said vacuum degassing | defoaming tank is air of 15 volume% or less. The method according to any one of claims 1 to 3,
The molten glass manufacturing method which makes the water vapor concentration of the atmospheric gas of the said vacuum degassing tank into 60 mol% or less by supplying the said gas to the upper space of the molten glass which distributes the said vacuum degassing tank. The method according to any one of claims 1 to 4,
By supplying said gas to the upper space of the molten glass which distribute | circulates the said vacuum degassing | defoaming tank, the gas flow of the flow direction of the said molten glass, and the flow direction of the said molten glass above the molten glass which distributes the said pressure reduction degassing tank A molten glass manufacturing method for forming at least one gas flow selected from the group consisting of a gas flow in an opposite direction and a gas flow in a direction perpendicular to the flow direction of the molten glass. A pressure reduction degassing vessel formed in the pressure reduction housing to be sucked under reduced pressure, the pressure reduction degassing tank for decompression degassing of the molten glass, and the pressure reduction degassing tank, and formed to introduce the molten glass before degassing into the pressure reduction degassing tank. As a pressure reduction defoaming apparatus of the molten glass which is connected to the said pressure reduction degassing tank and formed and introduce | transduces the molten glass after pressure reduction defoaming from the said pressure reduction defoaming tank,
And a gas introduction means for introducing a gas into the upper space inside the vacuum degassing tank, and a heating means for heating the gas introduced into the upper space. The method according to claim 6,
The degassing apparatus of the molten glass in which the said gas introduction means consists of a hollow tube, and the said heating means is formed along the pipeline which passes in the said pressure reduction housing of the said hollow tube. The method of claim 7, wherein
The degassing apparatus of the molten glass in which the said heating means is formed in the inside of the pipeline of the said hollow tube. 9. The method according to any one of claims 6 to 8,
The vacuum degassing apparatus of the molten glass which further has a vapor concentration measuring means which measures the vapor concentration of the atmospheric gas of the said vacuum degassing tank. 10. The method according to any one of claims 6 to 9,
The vacuum degassing apparatus of the molten glass in which the said gas introduction means is formed in the ceiling part or side surface of the vacuum degassing tank which forms the upper space on the molten glass inside a vacuum degassing tank. Of a glass product having a raw material melting step and a molding step as a preliminary step and a post step of the vacuum degassing step by the vacuum degassing apparatus of the molten glass according to any one of claims 6 to 10. Manufacturing method.

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