WO2016170634A1

WO2016170634A1 - Method for manufacturing float glass

Info

Publication number: WO2016170634A1
Application number: PCT/JP2015/062312
Authority: WO
Inventors: 史朗谷井; 誠二東; 鈴木　祐一
Original assignee: 旭硝子株式会社
Priority date: 2015-04-22
Filing date: 2015-04-22
Publication date: 2016-10-27
Also published as: KR20170138441A; CN107531541B; CN107531541A

Abstract

The purpose of the present invention is to provide a method for manufacturing float glass with which float glass for which adhesion of drops of tin is sufficiently suppressed can be obtained. The present invention relates to a method for manufacturing float glass by feeding molten glass onto the surface of a molten metal bath, which is a float bath containing tin, to shape the molten glass into a glass ribbon, pulling off the glass ribbon from the surface of the molten metal bath and drawing off the glass ribbon from the float bath, then annealing and cutting the glass ribbon to obtain the float glass. In this method for manufacturing float glass, the temperature inside the float bath is over 600°C and acetylene is fed to the float bath.

Description

Method for producing float glass

The present invention relates to a method for producing float glass.

In the glass manufacturing method by the float process, first, molten glass is continuously supplied to a horizontal bath surface of molten tin to form a belt-like glass (usually referred to as a glass ribbon). Pull up from the outlet side of the molten metal bath and pull out of the molten metal bath. Next, this glass ribbon is transported by a transport roll (lift-out roll), carried into a slow cooling furnace, slowly cooled while moving in the slow cooling furnace, and cut into a required length by a cutting device in the next process, thereby forming a plate shape The float glass is manufactured.
In the glass manufacturing method by the float method described above, one surface of the glass is formed by a molten metal bath surface, and the other surface of the glass is formed by spreading the molten glass on the molten metal. It is known as a production method suitable for mass production. For this reason, the float process is widely applied to the production of flat glass such as automotive glass and display glass.

FIG. 3 shows an example of a conventional float glass manufacturing apparatus applied to this type of float process. The manufacturing apparatus of this example includes a float bath 101 including a molten metal bath 100 of tin, a dross box 102 installed on the downstream side of the float bath 101, and a slow cooling furnace 103. A plurality of lift-out rolls 105 are installed horizontally inside the dross box 102, and a plurality of layer rolls 106 are installed horizontally inside the slow cooling furnace 103 (see Patent Document 1).
In the manufacturing apparatus shown in FIG. 3, the molten glass is supplied to the bath surface of the molten metal bath 100, stretched to a necessary thickness and width, and then the glass ribbon 108 is pulled out by the pulling force of the lift-out roll 105, Can be transported.

In the case of manufacturing float glass using a manufacturing apparatus as shown in FIG. 3, when the glass ribbon 108 is pulled up from the liquid surface of the molten metal bath 100 of tin, the lower surface of the glass ribbon 108 (the surface on the molten metal bath 100 side). ) May be pulled out of the float bath 101 with the tin droplets attached.
Normally, tin does not wet the glass, so it appears that no tin droplets adhere when pulling up the glass ribbon 108 from the molten metal bath 100 of tin.
However, if tin oxide (SnO ₂ , SnO) is generated on the liquid surface of the molten metal bath 100 of tin, the tin oxide is wet with the glass which is also an oxide. The tin oxide on the surface is transferred. Then, the tin of the molten metal bath 100 is also carried together with the tin oxide to be transferred, whereby tin droplets adhere to the glass ribbon 108.

As described above, the formation of tin oxide on the liquid surface of the molten metal bath 100 of tin causes the adhesion of tin droplets when the glass ribbon 108 is pulled up. However, the formation of tin oxide is caused by oxygen (O ₂ ) may be caused by leakage.
For this reason, conventionally, by supplying hydrogen (H ₂ ) gas into the float bath 101, tin oxide is reduced and decomposed, and tin droplets are prevented from adhering to the glass ribbon 108.

International Publication No. 2009/014028

However, in the area where the glass ribbon 108 is pulled up from the liquid level of the molten metal bath 100 in the float bath 101 (take-off portion), the space between the liquid level of the molten metal bath 100 and the glass ribbon 108 is covered up and down. Therefore, it is difficult for gas to circulate, and leaked oxygen tends to stay.
For this reason, the present inventors have clarified that the conventional reductive decomposition of tin oxide by supplying hydrogen gas has an insufficient effect of suppressing the adhesion of tin droplets to the glass ribbon 108 in the take-off portion. For example, even if the use of float glass is a building application or the like, a level of tin droplet adhesion that is not regarded as a problem is not permitted in recent electronic applications and the like.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for producing a float glass in which a float glass in which the adhesion of tin droplets is sufficiently suppressed can be obtained.

As a result of diligent studies to achieve the above object, the inventors of the present invention have made oxidation in the surface of the tin bath by making the inside of the float bath a specific atmosphere supplied with acetylene (C ₂ H ₂ ). The present inventors have found that the decomposition rate of tin can be improved and the effect of decomposing oxygen that causes tin oxide to be produced can be obtained.

That is, the present invention provides the following (1) to (4).
(1) Molten glass is supplied to the liquid surface of a molten metal bath, which is a tin bath provided in a float bath, and formed into a glass ribbon, and the glass ribbon is pulled up from the liquid surface of the molten metal bath and is removed from the float bath. A float glass manufacturing method for obtaining float glass by slowly cooling and cutting after drawing, wherein the temperature in the float bath is over 600 ° C., and acetylene is supplied into the float bath. Production method.
(2) The method for producing float glass according to (1) above, wherein the temperature of the take-off portion, which is a region where the glass ribbon in the float bath is pulled up from the liquid surface of the molten metal bath, is over 600 ° C.
(3) The float glass manufacturing method according to (2), wherein acetylene is supplied to the take-off portion.
(4) The method for producing float glass according to (2) or (3), wherein acetylene is supplied to a space between the liquid surface of the molten metal bath and the glass ribbon in the take-off portion.

According to the present invention, it is possible to provide a method for producing a float glass in which a float glass in which the adhesion of tin droplets is sufficiently suppressed can be obtained.

FIG. 1 is a configuration diagram illustrating a float glass manufacturing apparatus 1 according to the present embodiment. FIG. 2 is an enlarged configuration diagram illustrating the float bath 2 of the float glass manufacturing apparatus 1. FIG. 3 is a configuration diagram illustrating an example of a conventional float glass manufacturing apparatus.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited to the embodiment described below. In the present specification, “mass%” and “wt%”, “mass percentage” and “weight percentage” have the same meaning.

FIG. 1 is a configuration diagram illustrating a float glass manufacturing apparatus 1 according to the present embodiment. In FIG. 1, illustration of a part of the structure of the float glass manufacturing apparatus 1 (hereinafter, also simply referred to as “manufacturing apparatus 1”) is omitted.
As shown in FIG. 1, the manufacturing apparatus 1 causes the molten glass G supplied to the float bath 2 to flow along the surface of the molten metal bath 3 held in the float bath 2 to form a strip-shaped glass ribbon 5. The glass ribbon 5 is drawn out by a lift-out roll 7 provided in the dross box section 6.
In the manufacturing apparatus 1 of the present embodiment, the glass ribbon 5 is taken out from the outlet portion of the dross box portion 6, drawn into the slow cooling furnace 10 by the layer roll 9, cooled, washed, and then cut into a predetermined dimension. The Thus, a float glass having a desired size is obtained.

The molten glass G sent from the melting furnace (not shown) through the supply passage 11 is supplied to the inlet portion 2 a of the float bath 2 through a lip 12 provided at the end portion of the supply passage 11. . In the supply passage 11 on the upstream side of the lip 12, a tool 13 for adjusting the flow of the molten glass G is installed so as to be movable up and down. The supply passage 11 and the float bath 2 are each configured by assembling a plurality of heat-resistant materials such as refractory bricks, but are simplified in FIG.

As shown in FIG. 1, the float bath 2 includes a molten metal bath 2 </ b> A filled with a molten metal bath 3, and an upper structure 2 </ b> B installed on the upper portion of the molten metal bath 2 </ b> A. However, it is configured to be shielded from the external atmosphere as much as possible.
The float bath 2 is provided with a heater (not shown) so that the temperature in the float bath 2 can be adjusted for each region.

The float bath 2 can be filled with a molten metal bath 3 of tin (Sn). However, the tin bath constituting the molten metal bath 3 contains, for example, about 0.3 mass% of lead (Pb), zinc (Zn), iron (Fe), nickel (Ni), etc. as inevitable impurities. May be.

At the entrance 2a of the float bath 2, a front lintel 15 which is a front wall is formed, and the upper part of the front lintel 15 is connected to the ceiling wall 16. A rear end wall 17 is provided on the downstream end side of the float bath 2 so as to be connected to the ceiling wall 16, and an outlet portion 18 of the glass ribbon 5 is formed at a position near the liquid surface of the molten metal bath 3 on the rear end wall 17. Has been. In the float bath 2, the upper structure 2 </ b> B is configured by the front lintel 15, the ceiling wall 16, and the rear end wall 17.

Further, the upper structure 2B is provided with a pipe (not shown), and a reducing mixed gas composed of hydrogen and nitrogen is supplied from this pipe, so that the internal space of the float bath 2 is always maintained in a reducing atmosphere at atmospheric pressure or higher. Has been. The reducing atmosphere gas inside the float bath 2 slightly flows out to the dross box 6 side from the outlet 18 from which the glass ribbon 5 is drawn.

The dross box portion 6 provided on the downstream side of the float bath 2 includes a lower casing 6A and an upper casing 6B. In the present embodiment, three lift-out rolls 7 are horizontally provided at equal intervals on the lower casing 6A. ing. The lift-out roll 7 is generally composed of a roll body portion made of, for example, quartz and a shaft that supports the roll body portion. The number of liftout rolls 7 is not limited to three as in this embodiment, and any number of liftout rolls 7 may be provided as long as the glass ribbon 5 can be conveyed to the slow cooling furnace 10 side. The lower casing 6A has a side wall 6a on the float bath 2 side and a side wall 6b on the slow cooling furnace 10 side on the bottom wall 6c, and other side walls (not shown) standing on both sides in the width direction of the side wall 6a and the side wall 6b. It is comprised in the box shape which the upper surface side of each side wall opened.

In the lower part of the lift-out roll 7, a graphite seal block 21 and a wall-shaped pedestal 22 are disposed in order to block the air flow between the molten metal bathtub 2A and the slow cooling furnace 10. The seal block 21 is installed on the pedestal 22 so that the upper surface thereof is in contact with the roll surface of the lift-out roll 7, and the seal block 21 is partitioned so as to be somewhat airtight with the peripheral surface of the lift-out roll 7. Yes. The pedestal 22 is formed in a wall shape from a thick metal piece such as ductile cast iron, and is provided so as to partition the inside of the lower casing 6A.

In the lower space of the lift-out roll 7, for example, an inert gas such as nitrogen; a reducing gas such as hydrogen; a mixed gas thereof; a non-oxidizing gas such as a supply pipe 23 is installed. . In this embodiment, the non-oxidizing gas ejected from the supply pipe 23 is preferably ejected after preheating to 400 to 600 ° C. This is to prevent the glass ribbon 5 from being locally cooled by the ejection of the non-oxidizing gas.
The dross box section 6 is provided with a heater (not shown) so that the temperature of the glass ribbon 5 can be adjusted.

The upper casing 6B of the dross box section 6 is configured as a steel sealing gate, and has a ceiling wall 24 installed between the float bath 2 and the slow cooling furnace 10, and a stainless steel drape 25 suspended from the ceiling wall 24. And is installed on the upper side of the lower casing 6A. The plurality of drapes 25 depending on the ceiling wall 24 are arranged along the upper side of the contact position between the three lift-out rolls 7 and the glass ribbon 5 moving above. That is, these drapes 25 are arranged above the central axis of the lift-out roll 7 so as to extend over the entire length of the lift-out roll 7, and partition the internal space of the upper casing 6B into a plurality.
A plurality of layer rolls 9 are installed horizontally in the slow cooling furnace 10, and the glass ribbon 5 that has moved through the dross box 6 can be conveyed through the slow cooling furnace 10 by the plurality of layer rolls 9.

Next, the float bath 2 of the manufacturing apparatus 1 will be described in more detail based on FIG.
FIG. 2 is an enlarged configuration diagram illustrating the float bath 2 of the float glass manufacturing apparatus 1. As shown in FIG. 2, the float bath 2 has a region (take-off portion) TO in which the glass ribbon 5 is pulled up from the liquid surface of the molten metal bath 3 and separated. That is, the take-off portion TO indicates a position where the glass ribbon 5 is separated from the liquid surface when the glass ribbon 5 is continuously pulled up from the liquid surface of the molten metal bath 3.

As described above, the float bath 2 is provided with a heater (not shown), and is adjusted so that the temperature in the float bath 2 gradually decreases from the upstream side toward the take-off portion TO on the downstream side. Has been. This is because a certain degree of hardness is required to pull up the glass ribbon 5 at the take-off portion TO.
However, in the present embodiment, the temperature in the float bath 2 is over 600 ° C. throughout the region, and the temperature of the take-off portion TO is preferably over 600 ° C.
The temperature in the float bath 2 (including the temperature of the take-off portion TO) is a temperature including not only glass (molten glass G and glass ribbon 5) but also the surrounding atmosphere. Can be measured.

The bathtub rear end wall 2Aa is provided on the downstream end side of the molten metal bathtub 2A constituting the float bath 2 so as to form the outlet portion 18 of the glass ribbon 5 between the rear end wall 17 and the molten metal bathtub 2A. It can be said that the bathtub rear end wall 2Aa is a part of the molten metal bathtub 2A.

A hollow gas supply pipe 2Ab is embedded in the bathtub rear end wall 2Aa. The gas supply pipe 2Ab has one end connected to the outside of the float bath 2 and the other end connected to a space SP between the liquid surface of the molten metal bath 3 and the glass ribbon 5 in the take-off portion TO.
Note that the number of gas supply pipes 2Ab is not limited to one, and a plurality of gas supply pipes 2Ab are provided at predetermined intervals in the width direction of the float bath 2 (the back side or the front side in FIG. 2). May be provided. Further, the gas supply pipe 2Ab may not be embedded in the bathtub rear end wall 2Aa.

And in this embodiment, gas supply pipe 2Ac similar to gas supply pipe 2Ab is arrange | positioned also in the width direction both sides of space SP. Specifically, as shown in FIG. 2, the end face of the gas supply pipe 2Ac is disposed on one side in the width direction of the float bath 2 (the back side in FIG. 2) at a position facing the space SP. .
In addition, an end face of the gas supply pipe 2Ac (not shown) is similarly disposed on the other side in the width direction of the float bath 2 (front side in FIG. 2).

Therefore, the gas sent from one end of the gas supply pipe 2Ab and the gas supply pipe 2Ac can be discharged from the other end and supplied to the space SP.
In the present embodiment, as will be described later, a gas containing acetylene (C ₂ H ₂ ) is supplied into the float bath 2 using the gas supply pipe 2Ab and the gas supply pipe 2Ac, and preferably the float bath 2 A gas containing acetylene (C ₂ H ₂ ) is supplied to the space SP in the take-off portion TO.

In addition, it does not specifically limit as float glass manufactured using the manufacturing apparatus 1, For example, soda-lime glass and an alkali free glass are mentioned, An alkali free glass is preferable.
Examples of the alkali-free glass include SiO ₂ : 50 to 73%, Al ₂ O ₃ : 10.5 to 24%, B ₂ O ₃ : 0 to 12%, MgO in terms of mass percentage based on oxide. : 0-8%, CaO: 0-14.5%, SrO: 0-24%, BaO: 0-13.5%, MgO + CaO + SrO + BaO: 8-29.5%, and ZrO ₂ : 0-5% An alkali-free glass to be contained is mentioned.
At this time, when the strain point is high and the solubility is taken into consideration, the oxide-based mass percentage display is SiO ₂ : 58 to 66%, Al ₂ O ₃ : 15 to 22%, B ₂ O ₃ : 5 to An alkali-free glass containing 12%, MgO: 0 to 8%, CaO: 0 to 9%, SrO: 3 to 12.5%, BaO: 0 to 2%, and MgO + CaO + SrO + BaO: 9 to 18% is preferable.
When a high strain point is taken into consideration, the oxide-based mass percentage display is SiO ₂ : 54 to 73, Al ₂ O ₃ : 10.5 to 22.5%, B ₂ O ₃ : 0 to 5 Preferred is an alkali-free glass containing 5%, MgO: 0 to 8%, CaO: 0 to 9%, SrO: 0 to 16%, BaO: 0 to 2.5%, and MgO + CaO + SrO + BaO: 8 to 26%. .

Next, a method for manufacturing a float glass according to this embodiment using the float glass manufacturing apparatus 1 having the above-described configuration will be described.

First, molten glass G is supplied from the melting furnace to the supply passage 11, and the molten metal bath 3 at the inlet 2 a of the float bath 2 is adjusted by adjusting the flow rate of the molten glass G flowing on the lip 12 by the amount of damming of the twill 13. Molten glass G is supplied on top.
In the float bath 2, the molten glass G flowed on the molten metal bath 3 is formed into a strip-like glass ribbon 5 having a predetermined width and a predetermined thickness. The glass ribbon 5 is pulled up from the liquid level of the molten metal bath 3 by the lift-out roll 7 and moved to the dross box 6 side, and then the glass ribbon 5 is cooled while being conveyed through the slow cooling furnace 10 by the layer roll 9. . After the glass ribbon 5 cooled in the slow cooling furnace 10 is cooled, the glass ribbon 5 having a desired width and length can be manufactured by cutting the glass ribbon 5 into a length and a width necessary for the cutting step.

When supplying the molten glass G to the molten metal bath 3 and forming it into the glass ribbon 5, nitrogen gas and hydrogen gas are sent into the float bath 2 from a pipe (not shown) provided in the upper structure 2B, and a reducing atmosphere. In addition, the glass ribbon 5 is formed by gradually lowering the temperature so that the downstream side becomes a low temperature by controlling a heater (not shown).

In the present embodiment, in the float bath 2, it is preferable that the temperature of the take-off portion TO exceeds 600 ° C., and acetylene (C ₂ H ₂ ) is provided via the gas supply pipe 2Ab and the gas supply pipe 2Ac. It is preferable to supply a gas containing acetylene (C ₂ H ₂ ) to the space SP of the take-off portion TO.
As a result, the decomposition rate of tin oxide generated on the liquid surface of the molten metal bath 3 is improved rather than simply making the atmosphere of the hydrogen (H ₂ ) gas inside the float bath 2. In addition, oxygen that leaks into the float bath 2 and produces tin oxide also reacts with acetylene (C ₂ H ₂ ) before reacting with tin to become CO ₂ or H ₂ O to react with tin. No longer.

The reduction of tin oxide first proceeds as SnO ₂ → SnO. When the temperature in the float bath is 600 ° C. or lower, SnO can be converted to Sn even if acetylene (C ₂ H ₂ ) is used. The reduction does not progress further. However, SnO is reductively decomposed into Sn by setting the temperature above 600 ° C.
Acetylene (C ₂ H ₂ ) is considered to undergo reductive decomposition by acting on tin oxide after first becoming 2C + H ₂ .
Further, the reaction of oxygen (O ₂ ) first becomes carbon monoxide (CO), and finally becomes carbon dioxide (CO ₂ ).

Thus, the tin oxide on the liquid surface of the molten metal bath 3 is decomposed and the production of tin oxide is also suppressed, so that the transfer of tin oxide when the glass ribbon 5 is pulled up at the take-off portion TO is suppressed, As a result, the tin in the molten metal bath 3 is carried along with the tin oxide, and tin droplets are prevented from adhering to the glass ribbon 5. Then, by slowly cooling and cutting the glass ribbon 5, a float glass in which the adhesion of tin droplets is suppressed can be obtained.

The temperature in the float bath 2 is not particularly limited as long as it exceeds 600 ° C, and the temperature of the take-off portion TO is preferably more than 600 ° C. The temperature in the float bath, in particular, the temperature of the take-off portion TO is more preferably 620 ° C. or higher, more preferably 650 ° C. or higher, more preferably 700 ° C. or higher, because it is superior in the effect of decomposing tin oxide and oxygen. 750 degreeC or more is especially preferable. Although the upper limit temperature is not particularly limited, for example, 850 ° C. or less is preferable when considering changes in surrounding metal members.
Therefore, the preferred take-off portion TO can be rephrased as a region in the float bath 2 having a temperature of more than 600 ° C. and 850 ° C. or less.

Acetylene (C ₂ H ₂ ) is supplied from, for example, the gas supply pipe 2Ab and the gas supply pipe 2Ac as a mixed gas with nitrogen (N ₂ ).
At this time, the concentration of acetylene in the mixed gas is preferably 0.5 mol% or more, more preferably 1 mol% or more, and further preferably 2 mol% or more. The upper limit is not particularly limited, from the viewpoint of acetylene carbon produced during the decomposition of _{_{(C 2 H 2) (C}} ) are prevented from becoming aggregates, preferably 50 mol% or less.

Acetylene may be supplied to the entire float bath 2 from a pipe (not shown) provided in the upper structure 2B including the space SP of the take-off portion TO, but carbon adheres to the float bath 2. From the viewpoint of avoiding this, it is preferable to supply only to the space SP.

Hereinafter, examples according to the present invention will be described to further explain the present invention.

<Examples 1 and 2 and Comparative Example 1>
Using the manufacturing apparatus 1 of FIG. 1, molten glass G is supplied to the liquid surface of a molten metal bath 3 which is a tin bath, formed into a glass ribbon 5, slowly cooled and cut, and float glass (non-alkali glass) ) Was manufactured.
The composition of the molten glass G is expressed in terms of mass percentage on the basis of oxides: SiO ₂ : 59.70%, Al ₂ O ₃ : 16.90%, B ₂ O ₃ : 7.90%, MgO: 3. They were 27%, CaO: 4.00%, SrO: 7.69%, BaO: 0.10%, MgO + CaO + SrO + BaO: 15.06%, and contained substantially no SO ₃ .

At this time, in Examples 1-2 and Comparative Example 1, mixing of acetylene (C ₂ H ₂ ) and nitrogen (N ₂ ) from the gas supply pipe 2Ab and the gas supply pipe 2Ac into the space SP of the take-off portion TO. Gas (C ₂ H ₂ concentration: 2 mol%) (simply indicated as “C ₂ H ₂ ” in Table 1 below) was supplied.
In each example, a mixed gas (H ₂ concentration: 2 mol%) of hydrogen (H ₂ ) and nitrogen (N ₂ ) is supplied from a pipe (not shown) provided in the upper structure 2B. did.
For each example, a heater (not shown) in the float bath 2 was controlled to vary the temperature of the take-off portion TO as shown in Table 1 below.

<Comparative example 2>
The gas species supplied to the space SP from the gas supply pipe 2Ab and the gas supply pipe 2Ac is a mixed gas of hydrogen (H ₂ ) and nitrogen (N ₂ ) (H ₂ concentration: 2 mol%) (in Table 1 below, Float glass was produced in the same manner as in Example 1 except that it was changed to “H ₂ ”.

<Evaluation>
For the float glasses of Examples 1 and 2 and Comparative Examples 1 and 2 manufactured in this way, the number of tin droplets in an arbitrary visual field range (1000 mm × 1000 mm) on the surface on the molten metal bath 3 side was measured. If it is “◎” or “◯” according to the following criteria, it can be evaluated that a float glass in which the adhesion of tin droplets is suppressed is obtained. The results are shown in Table 1 below.
-“◎”: The number of tin droplets was 5 or less.
-"(Circle)": The number of tin droplets was more than 5 and 20 or less.
-"X": The number of tin droplets was more than 20.

As is clear from the results shown in Table 1 above, in Examples 1 and 2 in which acetylene was supplied and the temperature exceeded 600 ° C., the adhesion of tin droplets was suppressed.
At this time, it was found that the adhesion of tin droplets could be suppressed more in Example 2 in which the temperature was 750 ° C. than in Example 1 in which the temperature was 650 ° C.
On the other hand, Comparative Example 1 in which the temperature is 600 ° C. or lower and Comparative Example 2 in which the temperature is higher than 600 ° C. but no acetylene is supplied have an insufficient effect of suppressing the adhesion of tin droplets. I understood that.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. The contents of the Japanese patent application filed on November 11, 2013 (Japanese Patent Application No. 2013-233004) are incorporated in this application as a reference.

The technology of the present invention can be widely applied to glass manufacturing technology in general by the float method.

G ... Molten glass SP ... Space TO ... Take-off part 1 ... Float glass manufacturing device 2 ... Float bath 2A ... Molten metal bathtub 2Aa ... Bath rear end wall 2Ab ... Gas supply pipe 2Ac ... Gas supply pipe 2B ... Upper structure 2a ... Inlet part 3 ... Molten metal bath 5 ... Glass ribbon 6 ... Dross box part 6A ... Lower casing 6B ... Upper casing 6a ... Side wall 6b ... Side wall 6c ... Bottom wall 7 ... Lift-out roll 9 ... Layer roll 10 ... Slow cooling furnace 11 ... Supply passage 12 ... Lip 13 ... Twill 15 ... Front lintel 16 ... Ceiling wall 17 ... Rear end wall 18 ... Outlet 21 ... Seal block 22 ... Base 23 ... Supply pipe 24 ... Ceiling wall 25 ... Drape 100 ... Molten metal bath 101 ... Float bath 102 ... Dross box 103 ... Slow cooling furnace 105 ... Lift out roll 106 ... Layer low 108 ... glass ribbon

Claims

After molten glass is supplied to the liquid surface of the molten metal bath, which is a tin bath provided in the float bath, and formed into a glass ribbon, the glass ribbon is pulled up from the liquid surface of the molten metal bath and pulled out from the float bath A method for producing float glass, which is slowly cooled and cut to obtain float glass,
A method for producing float glass, wherein the temperature in the float bath is over 600 ° C., and acetylene is supplied into the float bath.
The method for producing a float glass according to claim 1, wherein a temperature of a take-off portion, which is a region where the glass ribbon in the float bath is pulled up from the liquid surface of the molten metal bath, is over 600 ° C.
The method for producing a float glass according to claim 2, wherein acetylene is supplied to the take-off portion.
The method for producing float glass according to claim 2 or 3, wherein acetylene is supplied to a space between the liquid surface of the molten metal bath and the glass ribbon in the take-off portion.