JP2001180950A - Improved manufacturing method for continuous thin sheet glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wide and thin sheet glass by molding. SOLUTION: An improved manufacturing method is characterized by relative slide of a support 12 to a glass ribbon GL, by moving the support 12 having the groove 12 B which is not parallel to a moving direction of the glass ribbon GL to an opposite direction of the moving glass ribbon GL being formed on a thin layer of vapor film 18, while a heat insulative atmosphere is formed around the glass ribbon GL with air and the thin layer of vapor film 18 by bringing the glass ribbon GL of an opposite side of the thin layer of vapor film 18 into contact with air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for producing a continuous thin sheet glass, and more particularly to an improved method for producing a continuous thin sheet glass for continuously forming molten glass into a thin sheet glass.

[0002]

2. Description of the Related Art As a method of manufacturing a sheet glass, a pulling method, a down-draw method, a roll-out method, a fusion method, a tin float method, and the like are known. The most widely used sheet glass forming method is the tin float method. . In this method, a molten glass in which a predetermined raw material is melted in a melting furnace is introduced into a molten tin bath in a reducing atmosphere, and is spread and moved in the vertical and horizontal directions using a mechanical external force. It gradually cools to near the point temperature to form a flat glass plate with a smooth surface.Since the smoothness of the product is significantly improved compared to the conventional pulling method, the polishing process is unnecessary. did.

[0003] However, the tin float method is concerned with the depletion of tin resources, the need to maintain a reducing atmosphere using hydrogen gas in order to prevent oxidation of metallic tin,
Tin penetrates into the glass from the surface in contact with tin and adversely affects the quality of the product, is vulnerable to shaking such as earthquakes, takes time to recover production after an earthquake, and consumes a large amount of energy for heating and keeping the glass Problems.

[0004] In addition, in forming a sheet glass by a roll-out method or a tin float method, since a high-temperature molten glass comes into contact with a base material (metal roll) or a medium (tin) having high thermal conductivity, the heat flow between the molten glass and the molten glass is high. The bundle is large and the molten glass is greatly affected by the temperature of the substrate and the medium. Therefore, there is a problem that the temperature control of the substrate and the medium is very important and difficult.

Further, in the roll-out method, since the glass surface is rapidly cooled by contact with the metal roll, it is unavoidable that contact marks with the roll, wrinkles and irregularities remain on the formed sheet glass surface. The quality of the product deteriorates. On the other hand, in the tin float method, it is necessary to perform slow cooling in which the temperature of the tin bath is gradually brought close to the temperature of the glass so as not to generate a temperature distribution on the surface or inside of the glass during cooling, and the molding time is long. Therefore, there is a problem in terms of production efficiency.

In the pulling method, the downdraw method, and the fusion method, both surfaces of the molten glass are brought into contact with air, which is a medium having smaller thermal conductivity than glass, but are caused by gravity due to vertical molding. It is difficult to control the tension on the molten glass, and in any case, the largest stress acts on the uppermost part, making it difficult to control the thickness of the sheet glass and complicating the temperature control of the medium to reduce it. Problem.

Further, as another manufacturing method, a proposal has been made in which a gas such as air is supplied from pores on the surface of a support, and molten glass is spread thereon to form a glass plate (Japanese Patent Publication No. Sho 50-36445).
However, it is extremely difficult to directly and continuously supply a gas and stably maintain a molten or fluid high-temperature glass.

[0008] As described above, the conventional sheet glass manufacturing methods involve problems of the base material and medium to be used, quality problems such as homogeneity, thickness uniformity, and surface smoothness of the sheet glass, and problems in forming. However, none of the production methods was satisfactory.

[0009] From such a background, the present applicant has proposed a basic technique relating to a sheet glass forming method in which molten glass is formed into a plate shape by using a thin layer of a vapor film obtained by vaporizing a vapor film forming agent (Japanese Patent Laid-Open No. Hei 10 (1994)). 9-295819). According to the manufacturing method of the sheet glass, effects such as resource saving, energy saving, high quality of the sheet glass, reduction of equipment and operation cost, easy job change, various correspondences from small-scale production to large-scale production, and the like are exhibited. be able to.

[0010]

However, the method of forming a glass sheet by molding a molten glass into a plate shape using a thin layer of a vapor film is a novel forming method that goes beyond the conventional conception. At this time, it is necessary to consider conditions for stably and rapidly forming a wide and thin plate glass to improve the process.

The present invention has been made in view of such circumstances, and a wide and thin plate glass can be stably formed by appropriately performing a moving direction of a glass ribbon and a moving direction of a support during molding. It is another object of the present invention to provide an improved method for producing a continuously thin glass sheet that can be formed quickly.

[0012]

In order to achieve the above object, the present invention provides a method for continuously forming a molten glass ribbon supplied on a support into sheet glass, wherein a liquid is contained inside. Introducing a vapor film forming agent, which is not a gas at least around normal temperature but a gas at or above the glass transition point of the glass, in a liquid state into the support made of a material or a structure which can be used. Sliding the glass at a temperature equal to or higher than the transition point with each other through a thin layer of a vapor film in which the vapor film forming agent has been vaporized, wherein the glass ribbon has a surface facing the support of the glass ribbon. The glass ribbon is formed continuously in an adiabatic environment with the gas and a thin layer of the vapor film by contacting the surface opposite to the surface with the gas, and the gas of the support itself is formed. Facing the glass ribbon By using a support structure in which a groove that is not parallel to the direction of movement of the glass ribbon is formed between surfaces or between supports, the support is moved in the direction opposite to the direction of movement of the glass ribbon during the molding. Features.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side view schematically showing a sheet glass forming apparatus for carrying out the present invention.

The molding apparatus 10 is mainly composed of supports 12, 12... Capable of containing a vapor film forming agent therein, a liquid supply device 16 for supplying the vapor film forming agent to the support 12, and a support 12
Conveyor 2 which slides the glass ribbon GL and the glass ribbon GL relatively through a thin layer 18 of a vapor film in which a vapor film forming agent is vaporized.
0 and a tension applying device 2 for applying tension to the glass ribbon GL
And 2. Also, on the front side of the molding apparatus 10,
A glass melt G in a molten state in which a glass raw material is dissolved is used as a support 1
A glass melting furnace 14 for supplying the glass melt 2 onto the support 2 is provided. The glass melt G is supplied to the forming apparatus 10 and then formed on the support 12 as a glass ribbon GL.

The glass melting furnace 14 melts a predetermined raw material to be a sheet glass and controls a melting temperature to prepare a glass melt G having a viscosity range and a temperature range suitable for molding. Since the viscosity of the glass melt G is controlled by the temperature, the viscosity is simultaneously controlled by controlling the temperature. In the case of molding a sheet glass, the dissolution depends on the glass composition.
In a temperature range of about 00 ° C., the reaction is carried out for a sufficient time so as to eliminate the glass bubble defect, the composition variation, and other defects. The glass melt G whose temperature and viscosity have been adjusted by the glass melting furnace 14 is supplied to the support 12 as a ribbon-like flow from an outlet hole 14A of the glass melting furnace 14.

The support 12 may be a continuous unit or a combination of unit units having a predetermined length. Further, the support 12 may be a belt-shaped one, a unit roll continuously arranged, or the like. However, in the present embodiment, a description will be given of an example in which a plurality of supports 12, 12,... Are arranged and fixed at a certain interval on the surface of the endless belt 20A of the belt conveyor 20. By arranging the supports 12 at intervals in this way, grooves 12B that are not parallel to the moving direction of the glass ribbon GL are formed between the supports 12. The groove 12B has the effect of preventing the attenuation described later,
This is effective in efficiently discharging excess steam from the interface between the gas and the thin layer 18 of the steam film. In addition, the groove 12B is
It is not limited to being formed between each other,
For example, as shown in FIG. 2 and FIG. 3, it may be formed on the support 12 itself, or may be formed both between the supports 12 and on the support 12 itself.

Endless belt 20 for moving support 12
A is stretched between a pair of rolls including a driving roll 20C and a driven roll 20D, and is driven by the rotation of the driving roll 20C. And the endless belt 20A is
Arrow 28 in FIG. 1 opposite to the moving direction of the glass ribbon GL
Orbital movement in the direction. As a result, the support 12 and the glass ribbon GL relatively slide through the thin layer 18 of the vapor film. Further, the belt conveyor 20 is provided with a guide plate 21 for guiding the upper movement path of the endless belt 20A, and the upper surface of the endless belt 20A moves stably by being guided by the guide plate.

The support 12 must have a material capable of containing a liquid therein or a structure capable of containing a liquid therein. For example, a porous or fibrous material is used.
In the case of a porous body, it is preferably a communication hole. The surface of the porous body has fine pores having a pore diameter of preferably 5 mm or less, more preferably 1 mm or less, and still more preferably 100 μm or less. Further, it is preferable that the material has high affinity with the vapor film forming agent.

As a basic material of the support 12, porous hydrophilic carbon is particularly preferable, but other materials such as cellulose, paper, wood, bamboo and other natural materials, thermoplastic resin In addition, synthetic polymer materials such as thermosetting resins and rubbers, and carbon materials can be suitably used. Also iron,
Metal materials such as stainless steel and platinum, aluminum oxide,
Ceramic materials mainly containing metal oxides such as zirconium oxide, silicon carbide and silicon nitride, metal carbides and metal nitrides can also be used. Note that the molding surface of the support 12 may be very smooth except for fine holes or fibrous irregularities, or may have certain irregularities.

A vapor film forming agent is supplied to the support 12 from a liquid supply device 16, and the vapor film forming agent is supplied to the glass ribbon GL.
The thin layer 18 of the vapor film is formed between the plurality of arranged supports 12, 12,... And the glass ribbon GL by instantaneous vaporization with high heat.

As the vapor film forming agent, various organic and inorganic substances which are liquid at ordinary temperature and gas at or above the glass transition point can be used. From the viewpoint of the operability of supply to the support 12, it is preferable that the melting point is 40 ° C or less and the boiling point under atmospheric pressure is 50 to 500 ° C, more preferably 300 ° C or less. Further, it is preferable that the vaporized vapor film forming agent does not chemically react so as not to adversely affect the glass, has low toxicity, and is nonflammable at the temperature used. Can be used. As described above, as the vapor film forming agent, it is necessary to appropriately select a liquid capable of instantaneously vaporizing due to the high heat of the glass ribbon GL and forming a stable vapor film. Since the thermal conductivity of the thin layer 18 of the vapor film formed by instantaneous vaporization with high heat is significantly smaller than the thermal conductivity of a liquid or a solid, an adiabatic environment is effective for the glass ribbon GL. Can be formed.

The liquid supply device 16 for supplying the vapor film forming agent to the support is mainly composed of a bath 30 provided below the belt conveyor 20, and the endless belt 20A moves around and a pair of rolls 20C, The support 12 supported by the endless belt 20 </ b> A is formed so as to go under the liquid of the vapor film forming agent in the bath tub 30 when reaching the lower side between 20 </ b> D. Thereby, the vapor film forming agent is supplied from the liquid supply device 16 to the support 12. In addition, the liquid supply device 16 is not limited to the bath tub type.
2 may be of a type in which a vapor film forming agent is sprayed, or the liquid in the bath is once contained in a wet roll (not shown), and then the wet roll is brought into contact with the support 12 to supply the vapor film forming agent. May be used.

The tension applying device 22 is composed of a pair of pinch rollers, and the glass ribbon GL is stretched by being pinched and rotated in the direction of pulling the glass ribbon GL at the end portion of the belt conveyor 20 (the drive roll 20C side). For tension. The pinch roller is a pinch roller 22A.
And a pinch roller 22B.
The rotation speeds of A and 22B can be varied. Thus, by changing the tension applied to the glass ribbon GL, the thickness and quality of the formed glass sheet are adjusted, and the contact time of the glass ribbon GL in contact with the thin layer 18 of the vapor film is controlled. .

[0025] Sheet glass forming apparatus 1 configured as described above.
Using 0, the improved production method of the continuous thin plate glass of the present invention will be described. An example of water will be described as a vapor film forming material.

When the glass melt G is continuously supplied in a ribbon form from the glass melting furnace 14 onto the support 12, the water held on the support 12 is instantaneously vaporized by the high heat of the glass ribbon GL. I do. Thereby, water vapor is continuously generated at the interface between the glass ribbon GL and the support 12, and the glass ribbon G
A thin layer 18 of a vapor film is formed between L and the support 12. Then, the glass ribbon GL is cast on the thin layer 18 of the vapor film from the downstream side of the glass melting furnace 14 toward the annealing furnace (not shown), and is stretched by applying a tensile force by the tension applying device 22. A plate-like glass is formed. At this time, it is necessary to relatively slide the support 12 and the glass ribbon GL via the thin layer 18 of the vapor film.

What is important in the formation of such a glass ribbon GL is that the opposite side of the glass ribbon GL facing the support 12 is brought into contact with the gas so that the gas and the thin layer 18 of the vapor film are separated. The glass ribbon GL is continuously formed in an adiabatic environment, and the glass ribbon GL is
Moving the support 12 having the grooves 12B that are not parallel to the moving direction of the glass ribbon GL in the direction opposite to the moving direction of the glass ribbon GL. Attenuation phenomena in which the width of G becomes narrow can be suppressed as much as possible, and wide and thin plate glass can be formed stably. That is, the glass ribbon G
Support 12 having groove 12B not parallel to the moving direction of L
Moves the bottom surface of the glass ribbon GL through the thin layer 18 of the vapor film in the direction opposite to the moving direction of the glass ribbon GL, and thus pushes the glass ribbon GL back to the upstream side which is the glass melting furnace 14 side. Will be. As a result, the glass ribbon GL
Since the glass melt G is less likely to be pulled during the flow of supplying the glass melt G onto the support 12 as compared with the case where the movement direction of the support 12 and the movement direction of the support 12 are the same, the attenuation phenomenon is reduced. Is suppressed.

Here, the adiabatic environment is a glass ribbon GL.
Is covered with a medium (thin layer of vapor film, gas) having a significantly lower thermal conductivity than glass, and is not heated through the medium to such an extent that cooling of the glass ribbon GL is hindered. There is an advantage that the temperature distribution in the thickness direction of the glass ribbon GL and the direction parallel to the glass ribbon GL surface in the molding process can be reduced.

As described above, various materials can be used for the support 12. However, the support 12 itself or between the supports 12 is formed by softening the steam generated from the support 12. The groove 12B is formed so as not to push up the glass ribbon beyond the point to cause undesired deformation. The fact that the direction of the groove 12B is not parallel to the moving direction of the glass ribbon GL causes the support 12 and the glass ribbon GL to slide relatively via the thin layer 18 of the vapor film. In addition to the above, it is more effective for suppressing the above-mentioned attenuation phenomenon.

That is, the groove 12B is slightly formed with the glass ribbon GL in the molten state or the softened state on the support 12 slightly interposed between the support 12 and the thin film 18 of the vapor film.
Since the level of the bottom surface is instantaneously reduced along with 2B, it is possible to apply a slight shearing force to the glass ribbon GL according to the relative movement of the support 12 and the glass ribbon GL. The direction of the shearing force can be adjusted by the direction of the groove 12B as well as the direction of the relative movement for sliding the glass ribbon GL and the support 12 through the thin layer 18 of the vapor film. The magnitude of the shearing force depends on the viscosity of the glass ribbon GL, the thickness of the thin layer 18 of the vapor film, the width of the groove 12B, and the like.
The depth and other shapes and patterns of the grooves 12B are determined by the relative moving speed of the glass ribbon GL and the support 12 and the like.

The width of the groove 12B is determined by the viscosity of the glass ribbon GL,
The allowable range varies depending on the temperature and the relative sliding speed of the support 12 and the glass ribbon GL,
It is necessary to be 0 mm or less, preferably 1 mm or more and 5 mm or less. When the width of the groove 12B is 1
When it exceeds 0 mm, the soft glass ribbon G which is in a sliding state with the support 12 and has a softening point higher than the advancing softening point.
L falls into the groove 12B and is easily bitten or left as a trace. On the other hand, when the width of the groove 12B is smaller than 0.5 mm, it is difficult to discharge the above-mentioned vapor, and the glass ribbon GL is likely to be undesirably deformed. In the case of the grooves 12B provided for purposes other than the above-mentioned discharge, the above-mentioned groove width generally prevents the glass ribbon GL from being unnecessarily dropped, and the glass ribbon GL is appropriately supported.
Desirable to be handled by. Such a groove 12B is
As described above, it is necessary that the glass ribbon GL be provided in a direction that is not parallel to the moving direction of the glass ribbon GL. If the glass ribbon GL is provided in parallel, the glass ribbon GL falls into the groove 12B or a trace is formed on the surface of the glass ribbon GL. The fear of leaving is increased. Therefore, the groove 12B is perpendicular to the moving direction of the glass ribbon GL (see FIG. 3) or at a certain angle (see FIG. 2).
It is indispensable to be provided with the above. When the viscosity of the glass ribbon GL is in an appropriate region and at an appropriate relative speed between the glass ribbon GL and the support 12, the glass ribbon GL is lightly handled by these grooves 12 </ b> B and is fixed to the glass ribbon GL. Is applied in the width direction or the longitudinal direction of the glass ribbon GL. The intended effect cannot be obtained if the depth of the groove 12B is too small.
Desirably, it is substantially 0.1 mm or more. If it is shallower than this, the drop of the glass ribbon GL may be slight, and the handling effect may be reduced.

Glass melt G in molten or softened state
Can be supplied in any form provided that it is in a viscosity range and temperature range suitable for molding and does not have an excessive distribution, such as orifice, lip, It may be supplied directly from the slit onto the support 12 or may be preliminarily formed by a roll or the like as long as excessive cooling can be prevented.

It is preferable that the temperature, viscosity and thickness of the glass melt G when it is subjected to molding are not extremely large. When the temperature difference is large, the influence of molding is likely to occur, which leads to various distortions, warpage, unevenness, etc. of the sheet glass as a product. Since viscosity is governed by temperature, it is controlled simultaneously by temperature management. Although the thickness is restored to some extent at the time of molding, it is better not to have a very large distribution at the time of supply like the temperature and the viscosity. If the thickness distribution is large, it will be difficult to repair during molding, and the product will be easily distorted and uneven.

In the present invention, the quality of the molding is high because the molding factors such as the thickness of the thin layer of the vapor film, the cooling rate, and the relative sliding between the support 12 and the glass ribbon GL are organically related. It is a method of manufacturing a sheet glass, and it is desirable that the control of these forming factors is controlled by a computer.

[0035]

As described above, according to the present invention,
Attenuation when the molten glass is supplied onto the support can be suppressed as much as possible, and the width of the glass ribbon can be prevented from being reduced, and the thickness can be reduced, so that a wide and thin plate glass can be continuously formed. Can be molded into

[Brief description of the drawings]

FIG. 1 is a side view schematically illustrating a sheet glass forming apparatus according to the present invention.

FIG. 2A is a top view illustrating an example of a groove formed in a support itself, and FIG. 2B is a side view thereof.

FIG. 3A is a top view showing another example of the groove formed in the support itself, and FIG. 3B is a side view thereof.

[Explanation of symbols]

10: sheet glass forming device, 12: support, 12B: groove,
14: glass melting furnace, 16: liquid supply device, 18: thin layer of vapor film, 20: belt conveyor, 22: tension applying device

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Kubo 1-1-1, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Asahi Glass Co., Ltd. (72) Inventor Kenji Oda 1-12-1 Yurakucho, Chiyoda-ku, Tokyo Asahi Glass (72) Inventor Isamu Kaneko Inside Asahi Glass Co., Ltd. 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa

Claims (3)

[Claims] 1. A method for continuously forming a molten glass ribbon supplied on a support into a sheet glass, wherein the support is made of a material or a structure capable of containing a liquid therein. A step of introducing a vapor film forming agent which is not a gas in the vicinity but a gas at or above the glass transition point of the glass in a liquid state; and Sliding the glass ribbon through a thin layer of vaporized vapor film, wherein the glass ribbon is brought into contact with a gas on the surface of the glass ribbon opposite to the surface facing the support. Thereby, the glass ribbon is continuously formed with the gas and the thin layer of the vapor film under an adiabatic environment, and the surface of the support itself facing the glass ribbon or between the supports. The moving direction of the glass ribbon and An improved method for producing continuous thin-walled glass, wherein the support is moved in a direction opposite to a moving direction of the glass ribbon during the molding using a support structure having non-parallel grooves. 2. The method according to claim 1, wherein said vapor film forming agent is water. 3. The method as claimed in claim 1, wherein the groove of the support has a depth of 0.1 mm or more and a width of 0.5 mm or more and 10 mm or less.