KR20210042088A - Manufacturing method of plate glass - Google Patents

Abstract

As a manufacturing method of plate glass, in the step of dissolving a glass raw material to obtain a molten glass, a step of forming a glass ribbon from the molten glass, a step of slow cooling the glass ribbon, and forming the glass ribbon , The molten glass is cooled so that the average cooling rate _{from the devitrification temperature (T L} ) to the softening point (T _{S) of the plate glass is 1500° C./min or more.}

Description

Manufacturing method of plate glass

The present invention relates to a method of manufacturing a plate glass.

Plate glass is mainly produced by a continuous molding process such as a down draw method and a float method (for example, Patent Documents 1 and 2).

A representative example of the down draw method is the fusion method.

In this method, the molten glass obtained by first dissolving the glass raw material is supplied to the upper portion of the molding member (hereinafter, referred to as "molding member"). The molded member has a substantially wedge-shaped cross section pointed downward, and the molten glass flows down along two opposite side surfaces of the molded member. The molten glass flowing down along both sides is merged and integrated at the lower end (referred to as "joining point") of the molding member, thereby forming a glass ribbon. After that, this glass ribbon is pulled downward while being slowly cooled by a pulling member such as a roller, and cut into a predetermined dimension.

On the other hand, in the float method, a glass ribbon is formed by conveying a molten glass on a molten tin. After that, the glass ribbon is slowly cooled and cut into a predetermined size.

Japanese Unexamined Patent Publication No. 2016-028005 Japanese Patent Publication No. 48-20761

In the conventional manufacturing method of plate glass, there is a problem in that it is difficult to continuously shape glass having a _{relatively low devitrification viscosity (hereinafter referred to as ``η L} '') in either of the down draw method and the float method. . This viscosity at the time of molding disclosed in the molten glass is typically 10 ⁴ poises (dPa · s) inde area of about, devitrification viscosity (η _L) is a low glass, that is, devitrification viscosity (η _L) of 10 ⁵ poises ( dPa·s) or less, the viscosity of the molten glass _{approaches the devitrification viscosity (η L} ) at the time of molding, and the possibility of devitrification increases.

Here, the term "deficit" refers to a phenomenon in which crystallization occurs in the glass and becomes opaque, and the devitrification viscosity (η _L ) means the viscosity at which devitrification occurs in the molten glass. In addition, the temperature of the molten glass in the devitrification viscosity (η _L ) is referred to as the _{devitrification temperature (T L ).}

For this reason, in the conventional continuous manufacturing method of plate glass, the devitrification viscosity (η _L ) is selected so as to be sufficiently higher than the viscosity at the start of molding of the molten glass. In other words, when the molten glass _{approaches the molding start temperature (also referred to as the working point (T W} )), the possibility of devitrification occurs in the molten glass during molding, so in the conventional method for producing plate glass, the devitrification temperature (T _L ) is It is selected so as to be sufficiently lower than the molding start temperature, that is, the working point (T _{W ).}

However, if the constraints on viscosity and temperature can be excluded or alleviated at the time of molding the glass ribbon as described above, it becomes possible to continuously manufacture a glass plate with a larger composition, thereby providing a glass plate that is more consistent with the needs of the user. I think I can.

The present invention has been made in view of such a background, and in the present invention, it is possible to continuously shape plate glass even from molten glass having a _{relatively low devitrification viscosity (η L} ), that is, a high devitrification temperature (T _{L ).} It is an object of the present invention to provide a method for manufacturing a plate glass.

In the present invention, as a manufacturing method of plate glass,

The process of dissolving a glass raw material to obtain a molten glass, and

A process of forming a glass ribbon from the molten glass, and

Having a step of slow cooling the glass ribbon,

In the process of forming the glass ribbon, the molten glass is cooled so that the average cooling rate _{from the devitrification temperature (T L} ) to the softening point (T _{S) of the plate glass is 1500° C./min or more.} .

In the present invention, it is possible to provide a method for producing a plate glass, capable of continuously forming a plate glass even from a molten glass having a relatively low devitrification viscosity (η _L ), that is, a high devitrification temperature (T _{L ).}

1 is a diagram schematically showing a relationship between each step and a glass temperature in a conventional float method.
2 is a diagram schematically showing a relationship between each step and a glass temperature in a manufacturing method according to an embodiment of the present invention.
3 is a diagram schematically showing a flow of a method for manufacturing a plate glass according to an embodiment of the present invention.
4 is a diagram schematically showing an example of a method of cooling a glass ribbon in a method for manufacturing a plate glass according to an embodiment of the present invention.
5 is a diagram schematically showing an example of another method of cooling a glass ribbon in the manufacturing method of plate glass according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described.

First, in order to better understand the present invention, a conventional method of manufacturing a plate glass will be briefly described. In addition, here, the float method is adopted as a conventional manufacturing method of plate glass, and its process is demonstrated.

The conventional float method has a melting process, a molding process, and a slow cooling process. First, in a melting process, a glass raw material is melt|dissolved in a melting furnace, and molten glass is manufactured. Next, in the molding process, the molten glass of the melting furnace is supplied onto the molten tin bath to form a glass ribbon. This glass ribbon is molded into a predetermined shape while conveying a molten tin phase. In addition, in the slow cooling process, the glass ribbon is slowly cooled in a slow cooling furnace.

Fig. 1 schematically shows a typical relationship between each step and glass temperature in a conventional float method.

In FIG. 1, the horizontal axis represents three steps of melting, molding, and slow cooling, and the vertical axis represents the approximate temperature of the glass in each step. Moreover, regarding some characteristic glass temperatures, the approximate viscosity of the glass at that temperature is also shown. In addition, the horizontal axis is arranged in the order in which the three processes are performed, and therefore can be considered as a time axis.

As shown in the profile 10 of FIG. 1, in the melting step, the glass is melted, and the temperature of the molten glass is equal to or higher than the _{working point (T W} ) (the viscosity of the glass is about 10 ^{4 poise).} . This molten glass is supplied to the molding process at the _{working point (T W ).} In other words, the onset temperature of the molding in the molding process is, T _W.

In the molding process, the temperature of the glass ribbon is, while moving the tin bath phase, the molding start temperature (T _W ) At slow cooling point (T _A ) (the viscosity of the glass is about 10 ¹³ poise), it is gradually cooled. Therefore, the temperature at the time of completion of molding is T _A.

Next, the glass ribbon enters a slow cooling process at a slow cooling _{point (T A ), and is slow cooled in this slow cooling process.} Then, the glass ribbon is cut, and plate glass is manufactured.

Here, as described above, in the conventional float method, when the working point T _W and the devitrification temperature T _L are too close, the possibility that the glass will deviate increases. For example, in _{the case of manufacturing a plate glass having a low devitrification viscosity (η L} ), the temperature of the molten glass is near the _{devitrification temperature (T L} ) at points where the flow of molten glass such as a melting process or a molding process is likely to be stagnant Since the staying time is long, a devitrification phenomenon may occur in the glass relatively easily.

So, to avoid this devitrification phenomenon, the work point (T _W) is a difference (ΔT) of the work point _(W T) and the devitrification temperature (T _L) is set to be larger enough. In other words, due to such a limitation on the devitrification phenomenon, there is a problem that the devitrification temperature T _L cannot be set in the vicinity of or higher than the working point T _W.

Such a problem also occurs in the conventional fusion method. Also in the fusion method, the melting process of the glass raw material (the _{temperature range above the working point (T W} )), the forming process of the glass ribbon (the temperature range from the working point (T _W ) to the slow cooling point (T _A )), and the glass ribbon. Slow cooling process (temperature range below the slow cooling point (T _A )) exists, and the working point (T _W ) is set so that the difference (ΔT) between the working point (T _W ) and the devitrification temperature (T _{L) becomes sufficiently large} Because it needs to be.

Further, in the case of the fusion method, the region below the above-described confluence point corresponds to the forming step of the glass ribbon.

As described above, in the conventional method for manufacturing a plate glass, there is a problem that it is difficult to mold a glass having a _{low devitrification viscosity (η L} ), that is, a relatively high devitrification temperature T _{L, by a continuous process.}

On the other hand, in one embodiment of the present invention,

As a manufacturing method of plate glass,

The process of dissolving a glass raw material to obtain a molten glass, and

A process of forming a glass ribbon from the molten glass, and

Having a step of slow cooling the glass ribbon,

In the process of forming the glass ribbon, the molten glass is cooled so that the average cooling rate _{from the devitrification temperature (T L} ) to the softening point (T _{S) of the plate glass is 1500° C./min or more.} .

In FIG. 2, an example of the relationship between each process and glass temperature in the manufacturing method of plate glass by one embodiment of the present invention is schematically shown. In Fig. 2, the horizontal axis represents three steps of melting, molding, and slow cooling, and the vertical axis represents the approximate temperature of the glass in each step. In addition, the horizontal axis is arranged in the order in which the three processes are performed, and therefore, can be considered as a time axis.

As shown in the profile 11 of FIG. 2, in the manufacturing method of the plate glass according to the embodiment of the present invention, the change in the glass temperature in the melting step and the slow cooling step is the case of the conventional melting step and the slow cooling step. It is almost the same as (see Fig. 1).

That is, the molten glass is supplied to the molding process at the temperature of the _{working point T W.} Moreover, the glass ribbon is conveyed by a slow cooling process at a temperature near the slow cooling _{point (T A ).} Moreover, in the forming process, the temperature of the glass ribbon changes from the forming start temperature (work point (T _W )) to the forming completion temperature (slow cooling point (T _A )).

However, as shown in the profile 11, in one embodiment of the present invention, the glass ribbon in the molding step is at least from the devitrification temperature (T _L ) to the softening point (T _S ) (the viscosity of the glass is about 10 ^7.65 Poise degree), it is rapidly cooled so that the average cooling rate (v _i ) becomes 1500 degreeC/min or more.

In such a profile 11, in a forming process, the temperature range from the forming start temperature (work point (T _W )) to the softening point (T _S ) of the glass ribbon can be passed quickly. For this reason, it becomes possible to significantly shorten the time for the _{molten glass to pass through the region of the devitrification temperature T L.} In addition, by this, it becomes possible to significantly suppress the possibility that the glass will deviate in the molding process.

Therefore, in one embodiment of the present invention, even if _{glass having a relatively high devitrification temperature T L} is used as a raw material, crystallization can be significantly suppressed. Further, accordingly, in the embodiment of the present invention _{, a glass having a relatively high devitrification temperature (T L} ), that is, a low devitrification viscosity (η _L ), can also be continuously produced.

In addition, the profile of the glass temperature shown in FIG. 2 is for illustrative purposes only, and is simplified. In fact, in one embodiment of the present invention, the process of manufacturing the plate glass does not exactly correspond to the profile shown in FIG. 2. It is clear to

For example, the slow cooling process of a glass ribbon does not necessarily need to start at _{the slow cooling point (T A ).} The slow cooling process may be started from a temperature higher or lower than the _{slow cooling point (T A ).}

However, in the conventional fusion method, a phenomenon in which the width of the glass ribbon decreases when the molten glass crosses the above confluence point of the molding member and falls, and molding of the glass ribbon starts, the width of the glass ribbon is reduced (hereinafter referred to as ``axis width phenomenon'' ) May occur. This is a phenomenon caused by shrinking of the glass ribbon in the width direction due to the surface tension.

Such a axial width phenomenon may reduce the accuracy of the width dimension of the glass ribbon to be molded and further, the plate glass to be manufactured.

On the other hand, in the manufacturing method of the plate glass according to the embodiment of the present invention, in the process of forming a glass ribbon, the molten glass has an average cooling rate _{from the devitrification temperature (T L} ) of the plate glass to the softening point (T _{S ).} It is cooled to 1500°C/min or more.

Because of such rapid cooling to the softening point (T _S ), in the manufacturing method of the plate glass according to the embodiment of the present invention, an additional effect of being able to significantly suppress the axial width phenomenon of the glass ribbon can be obtained.

For example, the axial width (ΔW) of the glass ribbon,

ΔW = W1-W2

When indicated by, in the manufacturing method of the plate glass according to the embodiment of the present invention, the shaft width amount (ΔW) of the glass ribbon can be 50 mm or less.

Here, W1 is the width of the glass ribbon immediately after the start of molding, that is, immediately after the start of free fall. In addition, W2 is the width of the glass ribbon immediately after completion|finish of molding. In general, W1 is the width of the glass ribbon in viscosity at the molding start temperature, and W2 is the width of the glass ribbon when the ^{viscosity becomes about 10 7.65 poise.}

It is preferable that the shaft width amount ΔW is 40 mm or less.

(Method of manufacturing plate glass according to an embodiment of the present invention)

Next, with reference to FIG. 3, the manufacturing method of the plate glass by one embodiment of this invention is demonstrated in more detail.

3 schematically shows a flow of a method for manufacturing a plate glass according to an embodiment of the present invention (hereinafter, referred to as a "first manufacturing method").

As shown in FIG. 3, the 1st manufacturing method,

(1) a process of dissolving a glass raw material to obtain a molten glass (step S110), and

(2) a step of forming a glass ribbon from the molten glass (step S120), and

(3) the step of slow cooling the glass ribbon (step S130) and,

(4) Step of cutting the slowly cooled glass ribbon to obtain plate glass (Step S140)

Has.

Hereinafter, each process is demonstrated.

(Step S110)

First, a glass raw material for flat glass is prepared.

The composition of the glass raw material is not particularly limited. However, in the first manufacturing method, a glass raw material for plate glass having a composition having a _{relatively high devitrification temperature (T L} ), that is, a low devitrification viscosity (η _{L ), can also be used significantly.}

Next, the glass raw material is supplied to the melting furnace, and molten glass is formed.

The melting temperature is not particularly limited, but may be, for example, a temperature at which ^{the viscosity of the glass becomes from 10 0} to 10 ^{3 poise.}

_{For example, the devitrification temperature (T L} ) of a plate glass produced from a glass raw material may be 800°C or higher, 850°C or higher, or 900°C or higher. In addition, the devitrification temperature (T _L ) and the working temperature (T _W ) ^{at which the viscosity becomes 10 4 dPa·s} The difference between T _{L and} T W is not particularly limited, but it is preferably 0°C or higher, preferably 50°C or higher, and more preferably 100°C or higher.

_{In addition, the softening point (T S} ) of the plate glass produced from the glass raw material is not particularly limited, but may be, for example, in the range of 400°C to 1100°C.

_{In addition, the devitrification viscosity (η L} ) of the plate glass produced from the glass raw material is, for example, in the range of 1 × 10 ⁰ to 1 × 10 ⁵ dPa·s (poise), and 1 × 10 ^1.5 to 1 × 10 ⁴ dPa It is preferable that it is a range of s (poise), and it is more preferable that it is a range of 1 × 10 ² to 1 × 10 ^{3 dPa·s (poise).}

The molten glass of the melting furnace is then transferred to a molding process.

(Step S120)

Next, a molding process is performed. In this process, the molten glass conveyed from the melting furnace is molded, and a glass ribbon is molded.

As described above, in the first manufacturing method, the molten glass is cooled so that the average cooling rate (v _{i ) from the devitrification temperature (T L} ) to the softening point (T _S ) becomes 1500° C./min or more.

The average cooling rate (v _i ) from the devitrification temperature (T _L ) to the softening point (T _S ) is, for example, 1800° C./min or more, preferably 2000° C./min or more.

The method of performing "quick cooling" of such a glass ribbon is not specifically limited.

For example, the glass ribbon may be rapidly cooled by injecting a cooling gas to the glass ribbon. Hereinafter, such a rapid cooling method is specifically referred to as "gas blow cooling method".

The gas used in the gas blow cooling method is not particularly limited as long as it does not adversely affect the glass ribbon. For example, an inert gas such as argon and nitrogen, or air or the like may be used as a cooling gas.

In addition, in the gas blow cooling method, it is preferable to inject a gas maintained at a sufficiently low temperature. In particular, the temperature of the gas to be injected is preferably lower than _{the softening point (T S) of the molten glass.} For example, the temperature of the gas to be injected is preferably 1°C to 100°C lower than _{the softening point (T S) of the molten glass.}

4 schematically shows a configuration example of an apparatus used when cooling a glass ribbon by a gas blow cooling method.

As shown in FIG. 4, in this configuration example, the apparatus 100 includes a housing member 110 and a gas supply member 125.

The accommodation member 110 has an upper member 112 and a bottom member 115.

The upper member 112 has an upper surface 112a and four side surfaces 112b surrounding the upper surface 112a. The upper surface 112a is formed with a concave portion 114 whose upper side is open. Moreover, the two opposing side surfaces 112b extend flat to each other along a vertical direction (a downward direction of the paper) and a direction perpendicular to the paper.

On the other hand, the bottom member 115 of the housing member 110 has a substantially inverted triangle shape in cross section, and has two slopes 116a and 116b and a vertex 116c connecting both slopes. The first slope 116a, the second slope 116b, and the vertex 116c are each also elongated in a direction perpendicular to the ground, and thus, the lower portion of the accommodation member 110 has a substantially triangular column shape. Have.

The upper part of the first slope 116a is connected to one side surface 112b of the upper member 112, and the upper part of the second slope 116b is connected to one side surface 112b of the upper member 112 It is connected.

The gas supply member 125 has one or two or more nozzles. For example, in the example shown in FIG. 4, the gas supply member 125 includes a first set of nozzles 127a and 127b disposed at a symmetrical position, and a second set of nozzles disposed at a symmetrical position. (129a and 129b) are provided.

The nozzles 127a and 127b of the first set and the nozzles 129a and 129b of the second set are provided at different height positions.

In addition, in the example shown in FIG. 4, the gas supply member 125 has a total of four nozzles 127a, 127b, 129a, 129b. However, this is a simple example, and the number and arrangement of the nozzles are not particularly limited as long as the glass ribbon can be properly cooled.

When using such an apparatus 100 to cool the molten glass by a gas blow cooling method, the molten glass 150 is supplied to the concave portion 114 of the upper member 112 of the housing member 110.

The concave portion 114 accommodates the molten glass 150. However, when the molten glass 150 exceeding the storage volume of the concave portion 114 is supplied, the molten glass 150 overflows along the opposite side surface 112b of the housing member 110, and the first molten glass It becomes the part 152a and the 2nd molten glass part 152b.

After that, the first molten glass portion 152a flows further downward along the first slope 116a of the housing member 110. Similarly, the second molten glass portion 152b flows further downward along the second slope 116b of the housing member 110.

As a result, the 1st molten glass part 152a and the 2nd molten glass part 152b reach the vertex 116c, and are integrated here.

Thereafter, the combined molten glass becomes the glass ribbon 170 and further advances in the vertical direction. That is, the apex 116c becomes the molding start position, and molding of the glass ribbon 170 starts from here.

Here, the apparatus 100 has the gas supply member 125 at a position of the glass ribbon 170, particularly at a position close to the molding start position (vertical point 116c). A cooling gas is injected toward the glass ribbon 170 from each of the nozzles 127a, 127b, 129a, 129b of the gas supply member 125.

Therefore, in the apparatus 100, the glass ribbon 170 can be quenched immediately after the molding start of the molten glass 150.

In addition, the configuration example of the apparatus 100 shown in FIG. 4 is a simple example, and a gas blow cooling method may be performed using another apparatus.

Further, as another cooling method, the glass ribbon may be quenched by continuously contacting the cooled roll with the glass ribbon. Hereinafter, such a rapid cooling method is referred to as a "roll cooling method".

In the roll cooling method, it is preferable to use a roll maintained at a sufficiently low temperature, for example. In particular, it is preferable to make the temperature of the roll _{lower than the softening point (T S) of the molten glass.} For example, it is preferable to make the temperature of a roll _{lower than the softening point (T S} ) of a molten glass by 1 degreeC-100 degreeC.

As a cooling method of a roll, methods, such as water cooling, air cooling, oil cooling, etc. are mentioned in which low temperature water, gas, oil, etc. are circulated and cooled.

5 schematically shows an example of a configuration of an apparatus used when cooling a glass ribbon by a roll cooling method.

As shown in FIG. 5, in this configuration example, the apparatus 300 for performing a roll cooling method includes a housing member 310 and at least one set of cooling rolls 360. In addition, although not shown in FIG. 5, the apparatus 300 further includes a conveying roller and a slow cooling furnace on the downstream side of the cooling roll 360. The conveyance roller has a role of drawing out the glass ribbon 370 sent out from the cooling roll 360 and introducing it into the slow cooling furnace.

The accommodation member 310 has a role of receiving the molten glass 350 supplied from a melting furnace (not shown) and overflowing the molten glass 350 that has not been fully accommodated downward. The housing member 310 may have the same shape as the housing member 110 shown in FIG. 4 described above.

When manufacturing a plate glass using such an apparatus 300, first, a molten glass 350 is supplied to the upper part of the accommodation member 310.

The molten glass 350 that overflowed because it was not fully accommodated in the housing member 310 flows down along the two opposite side surfaces of the housing member 310 and merges at the confluence point 320, whereby the glass ribbon 370 is do.

Thereafter, the glass ribbon 370 flows further downward, and is sandwiched between the two cooling rolls 360 and supported. As described above, the cooling roll 360 is maintained at a predetermined temperature by water, gas, oil, or the like, and the glass ribbon 370 in contact with the cooling roll 360 is rapidly cooled here.

As described above, a conveying roller (not shown) is provided downstream of the cooling roll 360. By this conveyance roller, the glass ribbon 370 is taken out to the downstream side of the cooling roll 360, and is introduced into a slow cooling furnace.

The glass ribbon 370 introduced into the slow cooling furnace is gradually cooled, and when it reaches a predetermined temperature, it is cut into predetermined dimensions, and plate glass is manufactured.

In this way, in the apparatus 300, the glass ribbon 370 can be rapidly cooled using the cooling roll 360.

Further, as another cooling method, a method of spraying a liquid onto a molten glass is exemplified. For example, the glass ribbon can be quenched by using a liquid which is relatively easy to vaporize as a spray liquid in a temperature range at or near the molding start temperature (operation point (T _{W )) of the molten glass.} Hereinafter, such a rapid cooling method is specifically referred to as "liquid spray cooling method".

Examples of liquids that can be used in the liquid spray cooling method include water, ethanol, and acetone. Even if these liquids come into contact with the glass ribbon, the possibility of adversely affecting the glass ribbon is low. The temperature of the liquid to be sprayed is preferably lower than _{the softening point (T S) of the molten glass.}

In addition, as another cooling method, the glass ribbon may be rapidly cooled by continuously dropping the glass ribbon onto a molten metal bath. The molten metal serving as the cooling source is not limited thereto, but includes tin, lead, zinc, mercury, copper, and the like. Further, the molten metal may be a single metal or may be an alloy of two or more selected from the metal group described above. It is preferable to make the temperature of the molten metal _{lower than the softening point (T S) of the molten glass.} For example, the temperature of the molten metal is preferably 1°C to 100°C lower than _{the softening point (T S) of the molten glass.}

In the manner described above, the molten glass is rapidly cooled to form a glass ribbon.

By such a rapid cooling treatment of the glass ribbon in the forming step, the time for the molten glass to pass through the _{devitrification temperature T L is significantly shortened.} As a result, even in the case of manufacturing plate glass from glass with a relatively high devitrification temperature (T _L ), that is, a low devitrification viscosity (η _L ), the possibility of the occurrence of devitrification in the glass ribbon during the molding process is significantly suppressed. can do.

(Step S130)

Next, the molded glass ribbon is slowly cooled. In a normal case, this step is performed in a slow cooling furnace.

In a normal case, the temperature of the glass ribbon supplied to the slow cooling furnace is before and after the _{slow cooling point (T A ).} When this is expressed by the viscosity of a glass, it becomes ^{about 10 13} poise.

Slow cooling point (T _A ) is in the range of 450°C to 700°C, for example.

(Step S140)

After that, the glass ribbon is cut to a predetermined dimension.

Through the above process, a plate glass having a desired dimensional shape can be manufactured.

The refractive index of the plate glass to be produced may be, for example, in the range of 1.40 to 2.20. Among these, when a high refractive index is required, 1.60 or more is preferable, 1.65 or more is more preferable, 1.70 or more is still more preferable, and 1.75 or more is especially preferable. Such a high refractive index plate glass can be applied, for example, to a video display device such as a high-performance liquid crystal panel, a light extraction member of a light emitting device, or the like. On the other hand, when it is necessary to use low dispersion, abnormal dispersion, or filter to block specific wavelengths, for example, to block light in the near-infrared region, 1.50 or less is preferable, 1.48 or less is preferable, and 1.45 or less is more preferable. . Such low-refractive-index glass can be used for correcting luminous sensitivity in an imaging device or for correcting chromatic aberration of an optical system for imaging.

Moreover, the Young's modulus of the plate glass to be produced may be in the range of 90 GPa to 150 GPa, for example. The Young's modulus is preferably 95 GPa or more, more preferably 100 GPa or more, still more preferably 105 GPa or more, and particularly preferably 110 GPa or more. Such a glass can be applied to, for example, a substrate for a magnetic disk for recording information, a substrate for a display, a support glass for semiconductor packaging, a carrier glass for a fan-out process, a cover glass for a mobile information device, or the like.

Example

Hereinafter, an embodiment of the present invention will be described.

(Example 1)

The manufacturing test of plate glass was performed by the following method.

4 schematically shows a part of an apparatus for manufacturing a plate glass used for a test.

As shown in FIG. 4, the apparatus 100 includes a housing member 110 and a gas supply member 125. In addition, although not shown in FIG. 4, the apparatus 100 further has a slow cooling portion on the downstream side of the gas supply member 125.

The accommodation member 110 has a role of receiving the molten glass supplied from a melting furnace (not shown) and overflowing the molten glass that has not been fully accommodated downward.

When manufacturing a plate glass using such an apparatus 100, first, a molten glass 150 is supplied to the upper part of the accommodation member 110.

The molten glass 150 is supplied to the concave portion 114 of the upper member 112 of the housing member 110.

The concave portion 114 accommodates the molten glass 150. However, the molten glass 150 exceeding the accommodation volume of the concave portion 114 is supplied, and the molten glass 150 overflows along the opposite side surface 112b of the housing member 110, and the first molten glass It becomes the part 152a and the 2nd molten glass part 152b.

After that, the first molten glass portion 152a flows further downward along the first slope 116a of the housing member 110. Similarly, the second molten glass portion 152b flows further downward along the second slope 116b of the housing member 110.

As a result, the 1st molten glass part 152a and the 2nd molten glass part 152b reach the vertex 116c, and are integrated here.

Thereafter, the combined molten glass becomes the glass ribbon 170 and further advances in the vertical direction. That is, the apex 116c becomes the molding start position, and molding of the glass ribbon 170 starts from here.

Next, from each nozzle 127a, 127b, 129a, 129b of the gas supply member 125 installed at a position close to the molding start position (vertical point 116c), cooling gas is injected toward the glass ribbon 170, , The glass ribbon 170 is rapidly cooled. In addition, the position and shape of each nozzle 127a, 127b, 129a, 129b are adjusted so that the cooling gas may be injected with respect to the glass ribbon 170 over the area|region of 100 mm of vertical directions.

The rapidly cooled glass ribbon 170 is introduced into the slow cooling section.

The glass ribbon 170 introduced into the slow cooling part is gradually cooled, and when it reaches a predetermined temperature, it is cut into predetermined dimensions, and plate glass is manufactured.

Using such an apparatus 100, a manufacturing test of plate glass was performed.

The used molten glass 150 has a working point (T _W ) (viscosity (η) = 10 ⁴ poise) of 870°C, and a devitrification temperature (T _L ) of about 1050°C (deflection viscosity (η _L ) = 1.1 × 10 ² poise), the softening point (T _S ) (viscosity (η) = 10 ^7.65 poise) was about 680°C, and the slow cooling point (T _A ) (viscosity (η) = 10 ¹³ poise) was 580°C. .

The temperature of the molten glass 150 supplied to the housing member 110 was about 1100°C. In addition, the temperature of the molten glass 150 (glass ribbon 170) at the vertex 116c (hereinafter, referred to as "T ₁ (°C)") was 1060°C.

In each of the nozzles 127a, 127b, 129a, 129b of the gas supply member 125, air having a temperature of 30° C. as a cooling gas was injected to the glass ribbon 170 to rapidly cool the glass ribbon 170. The conveyance speed of the glass ribbon 170 at this time was made into 300 mm/min. Moreover, the thickness of the glass ribbon 170 at this time was about 3.0 mm. In addition, the temperature of the glass ribbon 170 immediately after passing through the nozzles of the gas supply member 125 was 660°C.

Under such conditions, the time at which the glass ribbon 170 is at the apex 116c is set to a zero point (t ₁ ), and the temperature immediately after the glass ribbon 170 passes between the nozzles of the gas supply member (hereinafter, It was called "T ₂ (degreeC)"), that is, the time until it became 660 degreeC (referred to as "t ₂ (minute)") was measured.

From the obtained measurement results, the second average cooling rate (v _ii ) was calculated by the following equation:

Second average cooling rate (v _ii ) (℃/min) = (T1 ― T2)/t2 (1) Equation

As a result, the 2nd average cooling rate (v _ii ) was 2100 degreeC/min.

In addition, the average cooling rate (v _{i ) from the devitrification temperature (T L} ) of the glass ribbon 170 to the softening point (T _S ) is compared with the second average cooling rate (v _ii ), of v _i > v _ii Are in a relationship. Therefore, in this test, _{it is clear that the average cooling rate (v i} ) exceeds 2100°C/min.

As a result of measuring the shaft width amount ΔW of the glass ribbon 170 determined as described above, the shaft width amount ΔW was 25 mm.

As a result of observing the plate glass obtained after the test, no crystallization was observed in the plate glass.

(Example 2)

In the same manner as in Example 1, a plate glass production test was performed.

However, in this example 2, the conveyance speed of the glass ribbon 170 was made into 400 mm/min. In that case, the thickness of the glass ribbon 170 was about 2.2 mm. Other conditions are the same as in the case of Example 1.

As a result of the production test, the second average cooling rate (v _ii ) obtained from the above-described equation (1) was 2350°C/min.

In the obtained plate glass, occurrence of crystallization was not observed.

Moreover, the axial width amount (ΔW) of the glass ribbon 170 was 27 mm.

(Example 3)

In the same manner as in Example 1, a plate glass production test was performed.

However, in this Example 3, the conveyance speed of the glass ribbon 170 was 600 mm/min. In that case, the thickness of the glass ribbon 170 was about 1.5 mm. Other conditions are the same as in the case of Example 1.

As a result of the production test, the second average cooling rate (v _ii ) obtained from the aforementioned (1) formula was 2850°C/min.

In the obtained plate glass, occurrence of crystallization was not observed.

Moreover, the axial width amount (ΔW) of the glass ribbon 170 was 32 mm.

(Example 4)

The manufacturing test of plate glass was performed by the following method.

As a manufacturing apparatus, the apparatus 300 as shown in FIG. 5 mentioned above was used.

The used molten glass 350 has a working point (T _W ) (viscosity (η) = 10 ⁴ poise) of 870°C, and a devitrification temperature (T _L ) of about 1050°C (deflection viscosity (η _L ) = 1.1 × 10 ² poise), the softening point (T _S ) (viscosity (η) = 10 ^7.65 poise) was about 680°C, and the slow cooling point (T _A ) (viscosity (η) = 10 ¹³ poise) was 580°C. .

The temperature of the molten glass 350 supplied to the housing member 310 was set to about 1100°C. In addition, the temperature of the molten glass 350 (glass ribbon 370) at the confluence point 320 (hereinafter, referred to as "T ₁ (°C)") was 1060°C.

The two cooling rolls 360 maintained the surface temperature at 660° C., and the conveyance speed of the glass ribbon 370 on the surface of the cooling roll 360 was 300 mm/min. The thickness of the glass ribbon 370 conveyed between the two cooling rolls 360 was about 3.0 mm.

Under such conditions, the time at which the glass ribbon 370 is at the confluence point 320 is set to zero point (t ₁ ), and the temperature of the glass ribbon 370 is the temperature of the cooling roll 360 (hereinafter referred to as “T ₂ (DegreeC)"), that is, the time until it became 660 degreeC (referred to as "t ₂ (minute)") was measured.

In addition, the glass ribbon 370 is rapidly _{cooled to the temperature T 2} of the cooling roll 360 immediately after contacting the cooling roll 360 at a position in direct contact with the cooling roll 360.

So, here, the time until the temperature of the surface of the glass ribbon 370 becomes almost the same as _{the temperature T 2 of the cooling roll 360 was defined as t 2} (minutes).

From the obtained measurement results, the second average cooling rate (v _ii ) was calculated by the aforementioned (1) equation.

As a result, the 2nd average cooling rate (v _ii ) was 2350 degreeC/min.

In addition, the average cooling rate (v _{i ) from the devitrification temperature (T L} ) of the glass ribbon 370 to the softening point (T _S ) is compared with the second average cooling rate (v _ii ), of v _i > v _ii Are in a relationship. Therefore, in this test, _{it is clear that the average cooling rate (v i} ) exceeds 2350°C/min.

As a result of observing the plate glass obtained after the test, no crystallization was observed in the plate glass.

Moreover, the axial width amount (ΔW) of the glass ribbon 370 was 20 mm.

(Example 5)

In the same manner as in Example 4, a plate glass production test was performed.

However, in this Example 5, the conveyance speed of the glass ribbon 370 was made into 400 mm/min. In that case, the thickness of the glass ribbon 370 was about 2.2 mm. Other conditions are the same as in the case of Example 4.

As a result of the production test, the second average cooling rate (v _ii ) obtained from the aforementioned (1) formula was 3200°C/min.

In the obtained plate glass, occurrence of crystallization was not observed.

Moreover, the amount of shaft width (ΔW) of the glass ribbon 370 was 24 mm.

(Example 6)

In the same manner as in Example 4, a plate glass production test was performed.

However, in this Example 6, the conveyance speed of the glass ribbon 370 was 600 mm/min. In that case, the thickness of the glass ribbon 370 was about 1.5 mm. Other conditions are the same as in the case of Example 4.

As a result of the production test, the second average cooling rate (v _ii ) obtained from the above-described equation (1) was 4000°C/min.

In the obtained plate glass, occurrence of crystallization was not observed.

Moreover, the axial width amount (ΔW) of the glass ribbon 370 was 29 mm.

(Example 7)

In the same manner as in Example 1, except for cooling the glass ribbon using a molten tin bath, instead of the gas supply member, a production test of plate glass was performed. The temperature of molten tin was maintained at 660°C, and the conveyance speed of the glass ribbon on the surface of the molten tin bath was set to 410 mm/min. The thickness of the glass ribbon was about 2.2 mm.

As a result of the production test, the second average cooling rate (v _ii ) obtained from the above-described equation (1) was 1800°C/min.

In the obtained plate glass, occurrence of crystallization was not observed.

Moreover, the amount of shaft width (ΔW) of the glass ribbon was 25 mm.

(Example 8)

In the same manner as in Example 1, a plate glass production test was performed.

However, in this Example 8, the shape and position of each nozzle, and the supply amount of the cooling gas discharged from each nozzle were adjusted so that cooling gas might be injected over the area|region of 20 mm of the vertical direction of the glass ribbon 170. In addition, the supply amount of the cooling gas per unit area is the same as in Example 1. The conveyance speed of the glass ribbon 170 was 600 mm/min. In that case, the thickness of the glass ribbon 170 was about 2.3 mm. Other conditions are the same as in the case of Example 1.

As a result of the production test, the second average cooling rate (v _ii ) obtained from the above-described equation (1) was 420°C/min.

Crystallization was confirmed in the obtained plate glass.

Moreover, the amount of shaft width (ΔW) of the glass ribbon was 85 mm.

In Table 1 below, the results of the production test in each example were put together and shown.

Thus, in Examples 1 to 7, it was confirmed that the average cooling rate (v _{i ) from the devitrification temperature (T L} ) to the softening point (T _S ) of the glass ribbon can be made 1500° C./min or more. In addition, even when the working point (T _W ) (or the molding start temperature (T ₁ )) and the devitrification temperature (T _L ) are approaching, the average cooling rate (v _i ) of the glass ribbon is set to 1500°C/min or more. By doing so, it was confirmed that crystallization of molten glass was suppressed.

Moreover, in Examples 1 to 7, it was found that compared with Example 8, the amount of shaft width (ΔW) of the glass ribbon was significantly suppressed.

This application claims priority based on Japanese Patent Application No. 2018-150386 for which it applied on August 9, 2018, and the entire contents of the Japanese application are incorporated herein by reference.

10: Profile of conventional glass temperature
11: Profile of the glass temperature
100: device
110: accommodation member
112: upper member
112a: upper surface
112b: side
114: recess
115: bottom member
116a: slope 1
116b: slope 2
116c: vertex
125: gas supply member
127a, 127b: first set of nozzles
129a, 129b: second set of nozzles
150: molten glass
152a: first molten glass portion
152b: second molten glass portion
170: glass ribbon
300: device
310: receiving member
320: confluence point
350: molten glass
360: cooling roll
370: glass ribbon

Claims (10)

As a manufacturing method of plate glass,
The process of dissolving a glass raw material to obtain a molten glass, and
A process of forming a glass ribbon from the molten glass, and
Having a step of slow cooling the glass ribbon,
In the step of forming the glass ribbon, the molten glass is cooled so that the average cooling rate _{from the devitrification temperature (T L} ) to the softening point (T _{S) of the plate glass is 1500° C./min or more.} The method of claim 1,
The manufacturing method, wherein the cooling is performed by supplying a cooling gas to the glass ribbon. The method of claim 1,
The manufacturing method, wherein the cooling is performed by spraying a liquid capable of vaporizing when contacted with the molten glass to the glass ribbon. The method of claim 1,
The cooling is performed by bringing the glass ribbon into contact with a cooling roll maintained at a temperature lower than the softening point (T _{S ).} The method of claim 1,
The cooling is performed by contacting the glass ribbon with a molten metal maintained at a temperature lower than the softening point (T _{S ).} The method according to any one of claims 1 to 5,
The plate glass, wherein the devitrification temperature (T _L ) is 800°C or higher. The method according to any one of claims 1 to 6,
The plate glass, the devitrification temperature (T _L ) and the working temperature (T _W ) The difference of, T _L -T _W is 0 degreeC or more, and the manufacturing method. The method according to any one of claims 1 to 7,
The plate glass has a softening point (T _S ) of 600° C. or higher. The method according to any one of claims 1 to 8,
The said plate glass is a manufacturing method whose slow cooling point is in the range of 450 degreeC-700 degreeC. The method according to any one of claims 1 to 9,
The said plate glass has a devitrification viscosity in ^{the range of 1 × 10-1 × 10 5} dPa·s.

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