KR101276494B1 - Glass plate manufacturing method and glass plate manufacturing apparatus - Google Patents

Abstract

The glass plate manufacturing method of this invention melt | dissolves a glass raw material, and obtains a molten glass, the shaping | molding process of forming a glass ribbon from the said molten glass by the downdraw method, and at least one of the said molten glass and the said glass ribbon Volatile acceleration | stimulation process which promotes the volatilization of the volatile component from the surface of this, a slow cooling process which cools the said glass ribbon, and the cutting process which cut | disconnects the said glass ribbon and obtains a glass plate are included.
This invention relates to the glass plate manufacturing method which manufactures a glass plate using the down-draw method, and the glass plate manufacturing apparatus used especially preferably for this manufacturing method.

Description

Glass plate manufacturing method and glass plate manufacturing apparatus {GLASS PLATE MANUFACTURING METHOD AND GLASS PLATE MANUFACTURING APPARATUS}

This invention relates to the glass plate manufacturing method which manufactures a glass plate using the down-draw method, and the glass plate manufacturing apparatus used especially preferably for this manufacturing method.

As a flat panel display (henceforth "FPD"), such as a liquid crystal display and a plasma display, as a glass substrate, the glass plate with a thickness thin for example 1.0 mm or less is used. In recent years, enlargement of the glass plate for FPD glass substrates is advanced, For example, the magnitude | size of the glass plate called 8th generation is 2200 mm x 2500 mm.

In order to manufacture such a glass plate for FPD glass substrates, the downdraw method is most often used. For example, in the overflow downdraw method, the belt-shaped glass ribbon is continuously formed by overflowing the molten glass from the groove of the molding apparatus. At this time, the glass ribbon is pulled downward and the thickness is adjusted by the pulling speed. Then, a glass ribbon is cut | disconnected to predetermined length and a glass plate is manufactured.

For example, in patent document 1, the shaping | molding unit which is a part of the glass plate manufacturing apparatus as shown in FIG. 10 is disclosed. This molding unit is provided with the shaping | molding apparatus 7 and the heat insulation structure 8 surrounding the shaping | molding apparatus 7. As shown in FIG. The heat insulation structure 8 is for maintaining the temperature of the molten glass which overflows from the shaping | molding apparatus 7 by maintaining high temperature air around the shaping | molding apparatus 7, and is normally a gate which passes a glass ribbon ( Other than 81), it becomes a sealed structure.

Specifically, in the molding unit disclosed in Patent Document 1, the heat insulating structure 8 is constituted by a container-shaped main body 8A to be opened below and a gate structure 8B arranged to block the opening of the main body 8A. It is. The interior of the gate structure 8B is a cavity, and cooling air is supplied to the interior of the gate structure 8B through the cooling pipe 82. Thereby, with the shaping | molding unit disclosed by patent document 1, it is possible to cool the glass ribbon 9 immediately after formation.

Moreover, in the shaping | molding unit disclosed by patent document 1, the injection port 83 which blows the cooling air for cooling from the cooling pipe 82 in the space covered with the main body 8A is provided in the gate structure 8B, The glass ribbon 9 is also cooled by the cooling air flowing into the gate 81 from 83.

Japanese Patent Publication No. 2009-519884

Here, as a glass plate for FPD glass substrates and a glass plate for cover glass, high surface quality is calculated | required. For this reason, it is important to prevent a flaw on the surface of a glass plate.

By the way, a volatile component volatilizes in the interface which contact | connects air from glass (molten glass and glass ribbon immediately after formation) of a molten state. The inventors of the present invention think that if this phenomenon is effectively used in the downdraw method, it is possible to form a desired compressive stress layer on both main surfaces of the glass plate, thereby preventing the scratch on the surface of the glass plate. did.

However, when the cooling air is introduced into the heat insulating structure 8 like the molding unit disclosed in Patent Literature 1, since the molten glass flowing down the wall surface of the molding apparatus 7 is also cooled, the surface of the molten glass Volatilization of the volatile component of is suppressed. As a result, a compressive stress layer having a high stress value cannot be formed, and a glass plate that is hard to be scratched on the surface cannot be obtained (first problem).

In addition, even if forced convection occurs near the gate 81 like the molding unit disclosed in Patent Literature 1, the upper air, i.e., most of the air in the space covered by the main body 8A stops at that location and is melted. It does not change that volatilization of the volatile component from glass is suppressed (2nd subject).

This invention aims at providing the glass plate manufacturing method which can obtain the glass plate which is hard to be scratched on the surface in view of such a situation. Moreover, an object of this invention is to provide the glass plate manufacturing apparatus which can accelerate the volatilization of the volatile component from the molten glass which overflows from the shaping | molding apparatus used especially preferable for this manufacturing method.

MEANS TO SOLVE THE PROBLEM In order to solve the said 1st subject, this invention melt | dissolves a glass raw material and obtains a molten glass, the shaping | molding process of forming a glass ribbon from the said molten glass by the downdraw method, the said molten glass, and the said glass Provided are a glass plate manufacturing method including a volatilization promoting step of promoting volatilization of a volatile component on at least one surface of a ribbon, a slow cooling step of cooling the glass ribbon, and a cutting step of cutting the glass ribbon to obtain a glass plate.

MEANS TO SOLVE THE PROBLEM In order to solve the said 2nd subject, this invention is a shaping | molding apparatus which forms a glass ribbon by overflowing a molten glass from the both sides of a groove | channel, and inducing and fuse | melting the overflowed molten glass in the wall surface, The said shaping | molding And a heat insulating structure having a gate for passing the glass ribbon formed by the molding apparatus and surrounding the device, wherein the heat insulating structure includes the heat insulating structure for promoting volatilization of volatile components on the surface of the molten glass. It provides the glass plate manufacturing apparatus which introduce | transduces into the said heat insulation structure from the outside and discharges the gas which rises with the molten glass which flows down the wall surface of the said molding apparatus out of the said heat insulation structure.

According to this invention, the glass plate which is hard to be damaged in the surface in which the compressive stress layer with a high stress value was formed in both main surfaces can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows the glass plate manufacturing apparatus which enforces the glass plate manufacturing method which concerns on one Embodiment of this invention.
It is sectional drawing of the shaping | molding unit which is a part of glass plate manufacturing apparatus of 1st Embodiment.
3 is a perspective view of the molding unit shown in FIG. 2.
4 is a sectional view of a forming unit of a modification.
5 is a cross-sectional view of a forming unit of another variant.
6 is a cross-sectional view of another forming unit.
It is sectional drawing of the shaping | molding unit which is a part of glass plate manufacturing apparatus of 2nd Embodiment.
8 is a graph showing the relationship between the depth and the Si ratio in the glass plates of Examples 1 and 2. FIG.
9 is a graph showing the relationship between the internal stress and the depth of the glass plate of Example 1. FIG.
It is sectional drawing of the shaping | molding unit which is a part of the conventional glass plate manufacturing apparatus.

EMBODIMENT OF THE INVENTION Hereinafter, it demonstrates, referring drawings for specific content for implementing this invention. In addition, the following description is related to an example of this invention, Comprising: This invention is not limited by these.

<Glass plate manufacturing method>

The glass plate manufacturing method which concerns on one Embodiment of this invention is performed by the glass plate manufacturing apparatus 100 as shown in FIG. 1, for example. This glass plate manufacturing apparatus 100 is equipped with the heat insulation structure 2 surrounding the melting tank 51, the clarification tank 52, the shaping | molding apparatus 1, and the shaping | molding apparatus 1. As shown in FIG. In the melting tank 51, the melting process of melting a glass raw material and obtaining the molten glass 3 is performed, and in the clarification tank 52, the clarification process of clarifying the molten glass 3 is performed. The shaping | molding apparatus 1 forms a glass ribbon 4 from the molten glass 3 by the overflow downdraw method by performing a shaping | molding process. As the heat insulation structure 2, the volatilization promotion process which accelerates the volatilization of the volatile component in the surface of the molten glass 3 and in some cases the surface of the molten glass 3 and the glass ribbon 4 immediately after formation is performed. . Moreover, the glass plate manufacturing apparatus 100 performs the pulling apparatus containing the roller pair which pulls the glass ribbon 4 formed by the shaping | molding apparatus 1 below, and the cooling process which cools the glass ribbon 4, A cooling apparatus (not shown) and the cutting device (not shown) which cut | disconnect the glass ribbon 4 to predetermined length and perform the cutting process of obtaining a glass plate are provided. In addition, although not shown in figure, the stirring apparatus which improves the homogeneity of glass may be arrange | positioned by stirring the molten glass 3 with a stirring blade etc. between the clarification tank 52 and the shaping | molding apparatus 1.

Glass raw materials to be injected into the molten layer 51 include borosilicate glass, aluminosilicate glass, alumino borosilicate glass, soda lime glass, alkali silicate glass, alkali aluminosilicate glass, alkali alumino germanate glass and the like. It can use what was manufactured so that glass might be obtained. The glass obtained by the process of the present invention may be not limited to the above, when glass containing at least SiO ₂ and a volatile component.

Here, "volatile component" means SiO ₂ The saturated vapor pressure at the glass melting temperature (the glass temperature at which the viscosity of the glass becomes 1.0 × 10 ⁵ Pa · s or less) is more easily volatilized, in other words, SiO ₂ Higher component. Examples of the volatile component include Al ₂ O ₃ , B ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, MgO, CaO, SrO, BaO, ZrO ₂ , SnO ₂ , and the like. It is not limited. In addition, since B ₂ O ₃ , alkali oxides (Li ₂ O, Na ₂ O, K ₂ O) and alkaline earth metal oxides (MgO, CaO, SrO, BaO) are highly volatile, the glass composition is at least one of them. It is preferable to contain.

The volatile component, since the saturated vapor pressure in the glass melting temperature higher than SiO _2, the molding during or shortly after (in a glass melt state) SiO ₂ Volatilize before. That is, in the molding process in which the glass ribbon is formed from the molten glass, SiO ₂ is formed on the surface of the molten glass. Since other components volatilize, as a result, the silica rich layer in which content of Si atom exceeds content of Si atom in glass inside is formed in the surface of the glass plate after shaping | molding. Moreover, when a silica rich layer is formed on the surface of a glass plate, a compressive stress layer is formed in the two main surfaces of a glass plate by the difference of the thermal expansion coefficient with the glass plate inside.

In addition, content of the volatile component in the glass composition in the center position of the thickness direction of a glass plate is represented by mass%, It is preferable that it is 10% or more (or 15% or more), It is more preferable that it is 30% or more, 35% It is more preferable that it is more than (or 40% or more). If the content of the volatile component in the glass composition is less than 10%, the volatilization of the volatile component is not promoted, and the silica rich layer and the compressive stress layer are less likely to be formed on the glass plate surface. On the contrary, when it contains many volatile components, volatilization will increase too much and it will become difficult to homogenize glass. Therefore, it is preferable that it is 50% or less (or 45% or less, 42% or less), and it is more preferable that it is 40% or less.

As an example of the silicate glass for liquid crystal, there is an alumino boro silicate glass which consists of the following compositions substantially. In addition, in this specification, all content is represented by the mass% after that and shows more preferable content in parentheses. In addition, "substantially" is the meaning which allows presence of the trace component unavoidably mixed from industrial raw materials in the range of less than 0.1 mass%.

SiO ₂ : 50 to 70% (55 to 65%, 57 to 64%, 58 to 62%)

Al ₂ O ₃ : 5 to 20% (10 to 20%, 12 to 18%, 15 to 18%)

B ₂ O ₃ : 0-15% (5-15%, 6-13%, 7-12%)

MgO: 0 to 10% (0.01 to 5%, 0.5 to 4%, 0.5 to 2%)

CaO: 0 to 10% (1 to 9%, 3 to 8%, 4 to 7%, 4 to 6%)

SrO: 0 to 10% (0.5 to 9%, 3 to 8%, 3 to 7%, 3 to 6%)

BaO: 0 to 10% (0 to 8%, 0 to 3%, 0 to 1%, 0 to 0.2%)

ZrO ₂ : 0 to 10% (0 to 5%, 0 to 4%, 0 to 1%, 0 to 0.1%)

As another example of the silicate glass for liquid crystal, there is an aluminum boro silicate glass substantially composed of the following composition.

SiO ₂ : 50 to 70% (55 to 65%, 58 to 62%)

Al ₂ O ₃ : 10-25% (15-20%, 15-18%)

B ₂ O ₃ : 5-18% (8-14%, 10-13%)

MgO: 0 to 10% (1 to 5%, 1 to 2%)

CaO: 0-20% (1-7%, 4-7%)

SrO: 0 to 20% (1 to 10%, 1 to 3%)

BaO: 0 to 10% (0 to 2%, 0 to 1%)

K ₂ O: 0-2% (0.1-2%, 0.1-0.5%)

SnO ₂ : 0 to 1% (0.01 to 0.5%, 0.01 to 0.3%)

However, the content of the above composition of SnO _2, is a value converted to all of the components of Sn having a plurality of singers treated as SnO _2.

The silicate glass for cover glass contains the following components as an essential component, for example.

SiO ₂ : 50 to 70% (55 to 65%, 57 to 64%, 57 to 62%)

Al ₂ O ₃ : 5 to 20% (9 to 18%, 12 to 17%)

Na ₂ O: 6 to 30% (7 to 20%, 8 to 18%, 10 to 15%)

In addition, the following components may be included as an arbitrary component.

Li ₂ O: 0 to 8% (0 to 6%, 0 to 2%, 0 to 0.6%, 0 to 0.4%, 0 to 0.2%)

B ₂ O ₃ : 0 to 5% (0 to 2%, 0 to 1%, 0 to 0.8%)

K ₂ O: 0 to 10% (1 to 6%, 2 to 5%, 2 to 4%)

MgO: 0 to 10% (1 to 9%, 2 to 8%, 3 to 7%, 4 to 7%)

CaO: 0 to 20% (0.1 to 10%, 1 to 5%, 2 to 4%, 2 to 3%)

ZrO ₂ : 0 to 10% (0 to 5%, 0 to 4%, 0 to 1%, 0 to 0.1%)

As an example of the silicate glass for cover glass, there exists alkali-alumino silicate glass which consists of a following composition substantially.

SiO ₂ : 50 to 70%

Al ₂ O ₃ : 5 to 20%

Na ₂ O: 6-20%

K ₂ O: 0 to 10%

MgO: 0 to 10%

CaO: greater than 2 to 20%

ZrO ₂ : 0 to 4.8%

Moreover, preferably, the following conditions are satisfied.

(SiO ₂ content)-(Al ₂ O ₃ content) /2=46.5 to 59%

The content ratio of CaO / RO (where R is at least one selected from Mg, Ca, Sr and Ba) is greater than 0.3

The sum of SrO content and BaO content is less than 10%

The content ratio of (ZrO ₂ + TiO ₂ ) / SiO ₂ is 0 to less than 0.07

The content ratio of B ₂ O ₃ / R 1 ₂ O (wherein R 1 is at least one selected from Li, Na, and K) is 0 to less than 0.1

As another example of the silicate glass for cover glass, there exists alkali-alumino silicate glass which consists of the following compositions substantially.

SiO ₂ : 58-68%

Al ₂ O ₃ : 8-15%

Na ₂ O: 10-20%

Li ₂ O: 0 to 1%

K ₂ O: 1 to 5%

MgO: 2 to 10%

In addition, the molten glass 3 may be comprised substantially from said each component.

SiO ₂ is a component constituting the skeleton of the glass, and has an effect of increasing the chemical durability and heat resistance of the glass. When the content is too small, the effect is not sufficiently obtained, and when the content is too large, the glass tends to cause devitrification, making molding difficult, increasing the viscosity, and making the glass homogeneous.

B ₂ O ₃ is a component that lowers the viscosity of the glass and promotes dissolution and clarification of the glass. When there is too much content, the acid resistance of glass will fall and the homogenization of glass will become difficult.

Al ₂ O ₃ is a component constituting the skeleton of the glass, and has an effect of increasing the chemical durability and heat resistance of the glass. In addition, there is an effect of increasing the ion exchange performance and the etching rate. If the content is too small, the effect is not sufficiently obtained. On the other hand, when there is too much content, the viscosity of glass will rise and it will become difficult to melt | dissolve and acid resistance will fall.

MgO and CaO are components which lower the viscosity of the glass and promote the dissolution and clarification of the glass. Moreover, since the ratio which raises the density of glass is low in alkali earth metal, Mg and Ca are advantageous components in order to improve solubility while reducing the glass obtained. However, when the content is too much, the chemical durability of the glass is lowered.

SrO and BaO are components which lower the viscosity of the glass and promote the dissolution and clarification of the glass. Moreover, it is also a component which raises oxidizing property of a glass raw material and improves clarity. However, when the content is too large, the density of the glass rises, the weight reduction of the glass plate is not attempted, and the chemical durability of the glass decreases.

Li ₂ O is one of the ion exchange components and is a component that lowers the viscosity of the glass and improves the meltability and formability of the glass. Further, Li ₂ O is a component improving the Young's modulus of the glass (Young`s modulus). In addition, Li ₂ O has a high effect of increasing the compressive stress value in the alkali metal oxide. However, when the content of Li ₂ O is too large, the liquid viscosity is reduced, since the glass is liable to devitrification, the mass production of cheap glass using a downdraw method is difficult. Moreover, the thermal expansion coefficient of glass becomes high too much, the heat shock resistance of glass falls, and it becomes difficult to match thermal expansion coefficient with peripheral materials, such as a metal and an organic adhesive. Moreover, there exists a problem that deterioration of the ion exchange salt in the ion exchange process which is the process of strengthening a glass substrate becomes quick. In addition, when the low temperature viscosity is excessively lowered, stress relaxation occurs in the heating step after chemical strengthening, and the compressive stress value is lowered, so that sufficient strength cannot be obtained.

Na ₂ O is an ion exchange component and is an essential component that lowers the high temperature viscosity of the glass and improves the meltability and formability of the glass. Moreover, it is a component which improves the devitrification resistance of glass. If the content is less than 6%, the meltability of the glass is lowered, and the cost for melting increases. Moreover, since ion-exchange performance also falls, sufficient strength cannot be obtained. In addition, the coefficient of thermal expansion is excessively lowered, making it difficult to match thermal expansion coefficients with peripheral materials such as metals and organic adhesives. In addition, the glass is likely to cause devitrification, and the devitrification resistance is also lowered, so that it is not applicable to the overflow downdraw method, making mass production of inexpensive glass difficult. On the other hand, when content exceeds 20%, low-temperature viscosity will fall, thermal expansion coefficient will become excess, impact resistance will fall, and thermal expansion coefficients, such as a metal and an organic adhesive, will become difficult to match. Moreover, since the devitrification resistance fall by glass deterioration also arises, mass production of the inexpensive glass using the down-draw method becomes difficult.

K ₂ O is an ion exchange component, and is a component capable of improving the ion exchange performance of the glass by including. K ₂ O is also a component that lowers the high temperature viscosity of the glass and improves the meltability and moldability of the glass and at the same time improves the devitrification resistance. However, when the content of K ₂ O is too large, the low temperature viscosity is lowered, the coefficient of thermal expansion becomes excessive, since the impact resistance decreases, which is not preferable in the case of application as a cover glass. In addition, the thermal expansion coefficient hardly matches with peripheral materials such as metals and organic adhesives. Moreover, since the devitrification resistance fall by glass deterioration also arises, mass production of the inexpensive glass using the downdraw method becomes difficult.

Na ₂ O and K ₂ O are components that elute from glass to deteriorate TFT characteristics, or increase the coefficient of thermal expansion of glass to cause damage to the substrate during heat treatment. It is not preferable to contain a large amount. Therefore, by incorporating a specific amount of the above components into the glass, the basicity and the meltability of the glass are increased while the deterioration of the TFT characteristics and the thermal expansion of the glass are suppressed within a certain range, and the oxidation of the metal which is hydroly fluctuated easily, It is also possible to exercise.

ZrO ₂ is a component that significantly improves the ion exchange performance and increases the viscosity and the strain point near the devitrification temperature of the glass. Further, ZrO _2, it is also a component for improving the heat resistance of the glass. However, when the content of ZrO ₂ is too large, the devitrification temperature is increased, and the substantial decrease covered.

TiO ₂ is a component that improves the ion exchange performance and decreases the high temperature viscosity of the glass. However, when the content of TiO ₂ is too large, resulting in substantial degradation covered. In addition, the glass is colored, which is not preferable for a cover glass or the like. In addition, since the glass becomes colored, the ultraviolet ray transmittance also decreases, and thus, a problem arises in that the ultraviolet curable resin cannot be sufficiently cured when the treatment using the ultraviolet curable resin is performed.

A clarifier can be added as a component which defoases the bubble in glass. The clarifier is not particularly limited as long as the environmental load is small and the clarity of the glass is excellent, but for example, at least one selected from metal oxides such as tin oxide, iron oxide, cerium oxide, terbium oxide, molybdenum oxide, and tungsten oxide Can be mentioned.

In addition, As ₂ O ₃ , Sb ₂ O ₃ and PbO generate | occur | produce the reaction accompanying a fluctuation | variation of a hydrolysis in a molten glass, and are the substance which has the effect of clarifying glass, However, since these are substances with a large environmental load, this implementation is carried out. in the form of a glass plate, is substantially free of _{as 2 O 3, Sb 2 O} 3 and PbO in the glass. Further, the means described in the _{specification, As 2 O 3, Sb 2} O 3 , and does not contain PbO substantially, as less than 0.01% do not exclude impurities and not intentionally contained in an.

Next, especially preferable aspect is demonstrated about the silicate glass for liquid crystals. As mentioned later, it is preferable that the molten glass 3 contains many volatile components from a viewpoint of making the stress value of a compressive stress layer high. For silicate glass containing SiO ₂ as the main component, SiO ₂ Each component other than SiO ₂ It is a volatilization component in a broad sense because it is relatively easy to volatilize during melting. Examples of the highly volatile volatile component in the glass composition exemplified above include B ₂ O ₃ , SnO ₂ (volatile as SnO), and K ₂ O. Therefore, it is preferable that the content rate of these components is high. However, when volatilization becomes excessive, a problem arises at the time of molding, so the upper limit of the content rate of B ₂ O ₃ is more preferably 14 mass%, particularly preferably 13 mass%. Further, the higher the content of SnO _2, there is a case that the devitrification occurs in the glass. Accordingly, in the viewpoint of preventing the devitrification of a glass, the upper limit of the content of SnO ₂ is particularly preferably more preferably from 0.5% by weight and 0.3% by weight. Further, K ₂ O is used as the fusion promoter of the glass, because of the addition in a large amount to cause a problem eluted from the glass sheet, the upper limit of the content of K ₂ O is more preferably 0.5% by mass.

As the glass plate manufacturing method of this embodiment, a volatilization promotion process is performed in the heat insulation structure (2). For this reason, the silica rich layer is formed in the manufactured glass plate on the surface. Hereinafter, this glass plate is demonstrated.

(1) silica rich layer

The "silica rich layer" refers to the Si atomic content in the glass composition in the center of the thickness direction of the glass plate as a reference value, and from the position at which the ratio of the Si atomic content in the glass composition to the reference value becomes 1.05 or more to the main surface of the glass plate. Indicates the area of.

A glass plate surface, the silica-rich layer which is more than the content of SiO ₂ content of the center in the thickness direction of the glass plate is formed of SiO _2. The depth of this silica rich layer is preferably more than 0 to 20 nm, more preferably more than 0 to 15 nm (also 1 to 12 nm, 2 to 11 nm, 3 to 11 nm). Thereby, the compressive stress layer of sufficient depth can be obtained. On the other hand, although the depth of a silica rich layer can be made deep by promoting volatilization from the surface of the glass ribbon immediately after formation, deviation of shaping | molding appropriate condition or fall of productivity arise by it. Therefore, it is preferable that the depth of a silica rich layer is 30 nm or less.

As a silica rich layer, it is preferable that the maximum value of the ratio of Si atom content in the glass composition with respect to the said reference value is 1.06 or more, and 1.08 or more (Moreover, 1.10 or more, 1.12 or more, 1.14 or more, 1.15 or more, 1.16 or more, 1.18 or more) It is more preferable).

Or it is preferable that the maximum value of Si atom content in the glass composition of a silica rich layer is 1% or more more than Si atom content of the center of the thickness direction of a glass plate, and is 1.5% or more (more, 2% or more, 2.5%) More than 3%), many are more preferable.

Alternatively, the silica up to a value of SiO ₂ content of the rich layer, than the SiO ₂ content of the center in the thickness direction of the glass sheet at least 0.5% higher is preferred, and greater than or equal to 1% (and more than 1.5%, 2% or more, more than 2.5% , 3% or more) is more preferable.

By satisfy | filling the conditions mentioned above, a silica rich layer can obtain the difference of sufficient thermal expansion coefficient between a glass plate surface and an inside of a glass plate, and can form a compressive stress layer in the both main surfaces of a glass plate. Moreover, the Vickers hardness and durability of the glass plate surface can also be improved, and it can prevent that a glass plate is broken.

Here, when the Si atom content and SiO ₂ content of the silica-rich layer formed on the glass sheet surface is less than the above range, it is not possible to obtain a difference between a sufficient coefficient of thermal expansion, sufficient compression of large stresses between the glass surface and the glass sheet inside The layer is not formed or sufficient Vickers hardness or durability cannot be obtained.

On the other hand, even if Si atom content and SiO ₂ content of the silica-rich layer is that if I exceeding the above upper limit, the quality (physical properties, thermal properties, chemical properties) of the glass sheet away been changed, it can not be used in conventional applications have. For example, cutting and etching of a glass plate become difficult.

Further, in the silica-rich layer formed on the glass plate produced according to the present embodiment, Si atom content and SiO ₂ content of the larger position is not different from the glass surface, sometimes in the range of from greater than 0 to 5 nm from the glass plate surface have.

When the silica rich layer is formed on the surface of the glass plate, a compressive stress layer is formed on portions along both main surfaces of the glass plate due to the difference in thermal expansion coefficient between the surface of the glass plate and the inside of the glass plate, and a tensile stress layer between these compressive stress layers. Is formed. According to the glass plate manufacturing method of this embodiment, the stress profile drawn by plotting a compressive stress value and a tensile stress value becomes specific.

Although it is possible to form a compressive stress layer in both main surfaces of a glass plate by quenching a glass ribbon in a slow cooling process, the stress profile of the glass plate obtained in this way is a shape like drawing a parabola (the compressive stress layer in this case is glass Is caused by the difference in heat transfer between the surface of the glass plate and the inside of the glass plate due to a constant heat transfer rate). On the other hand, as a glass plate obtained by the glass plate manufacturing method of this embodiment, the compressive stress layer is formed by a volatilization promotion process, ie, the difference of the thermal expansion coefficient resulting from a silica rich layer contributes to formation of a compressive stress layer. For this reason, a compressive stress layer is formed in the area | region near the main surface of a glass plate (that is, the depth of a compressive stress layer is shallow). Moreover, the compressive stress layer has a larger stress value than that obtained when the compressive stress layer is formed by quenching (the compressive stress layer and the tensile stress layer are balanced, and thus, when the compressive stress layer becomes thin, Stress value is high). That is, in the vicinity of the surface of the glass plate obtained by the glass plate manufacturing method of this embodiment, since the compressive stress layer which has a larger stress value is formed than the case where the compressive stress layer was formed by quenching, the surface of a glass plate becomes hard to produce a scratch more. . In addition, a tensile stress layer has a substantially constant stress value except the both sides of the thickness direction of a glass plate. That is, the stress profile of the glass plate obtained by the glass plate manufacturing method of this embodiment forms a U-shape with a flat bottom.

(2) compressive stress layer

It is preferable that the depth of a compressive stress layer is 50 micrometers or less. The depth of the compressive stress layer can be deepened by promoting volatilization on the surface of the glass ribbon immediately after formation. However, the compressive stress layer is caused to deviate from the molding proper condition or to reduce the productivity. The depth of the compressive stress layer is more preferably 45 µm or less, still more preferably 40 µm or less, and particularly preferably 38 µm or less. In addition, the compressive layer stress layer depth in this specification has shown the depth of the compressive stress layer formed in the part along one main surface of a glass plate. That is, the compressive stress layer of the said depth is formed in each of both main surfaces of a glass plate.

Moreover, it is preferable that the depth of a compressive stress layer is more than 10 micrometers. When the depth of the compressive stress layer is to some extent, it is possible to prevent the glass plate from being easily broken by minute scratches caused by handling. Even if a deeper wound occurs, in order to prevent breakage of the glass plate, the depth of the compressive stress layer is more preferably 15 µm or more, and more preferably 20 µm or more (particularly, 25 µm or more, 30 µm or more, 35 µm). Above).

Alternatively, the depth of the compressive stress layer is preferably less than 1/13 of the plate thickness of the glass plate, and is less than 1/15 (also less than 1/17, less than 1/20, less than 1/22, less than 1/24). It is more preferable.

It is preferable that the maximum compressive stress value of a compressive stress layer is 4 MPa or less. It is because the workability of a glass plate will worsen when it exceeds 4 MPa. The maximum compressive stress value is more preferably 3.7 MPa or less, and still more preferably 3.5 MPa or less (particularly 3.0 MPa or less and 2.8 MPa or less).

In addition, the maximum compressive stress value of the compressive stress layer is preferably 0.4 MPa or more, and more preferably 1 MPa or more (more than 1.5 MPa or more and 2 MPa or more) from the viewpoint of improving the mechanical strength of the glass plate.

In addition, "stress value" in this specification is a value when it measures every 10 micrometers range in the thickness direction from the main surface of a glass plate. Therefore, there exists a case where the compressive stress value which locally exceeds the range of the said compressive stress value exists (the same also applies to the tensile stress value mentioned later).

(3) tensile stress layer

As above-mentioned, the tensile stress layer formed in the glass plate inside has a substantially constant stress value except the both sides of the thickness direction of a glass plate. Difference between the maximum value and the minimum value of the tensile stress value at the center portion 4/5 (hereinafter, simply referred to as the "tensile center region") of the tensile stress layer excluding each side 1/10 in the thickness direction of the glass plate (tensile tension) It is preferable that it is 0.2 MPa or less, and it is more preferable that it is 0.15 MPa or less (0.10 MPa or less, 0.05 MPa or less, 0.02 MPa or less).

When the tensile stress value of a tensile stress layer becomes large, when cut | disconnecting a glass plate, the scribe line of the predetermined depth put in for cutting may extend out of assumption, and it may become difficult to divide a glass plate by a desired dimension. According to this embodiment, even if the maximum compressive stress of a surface layer is enlarged, it is possible to keep tensile stress at a small value. For example, it is possible to set it as (absolute value of the maximum compressive stress of a surface layer) / (absolute value of the maximum tensile stress of a tensile stress layer) = 6 or more. For example, it is preferable that the maximum tensile stress value of a tensile stress layer is 0.4 Mpa or less. When the maximum tensile stress value of the tensile stress layer exceeds 0.4 MPa, when the glass plate is cut, when a scribe line of a predetermined depth inserted for cutting is stretched out of the assumption, it becomes difficult to divide the glass plate into desired dimensions. Because there is. The maximum tensile stress value of the tensile stress layer is more preferably 0.3 MPa or less, and still more preferably 0.2 MPa or less (particularly 0.15 MPa, 0.10 Mpa or less).

In addition, since the stress value of the tensile stress layer formed inside the glass plate is substantially constant in the thickness direction of the glass plate, the effect that the glass plate is less likely to be broken compared to the case where the stress value of the tensile stress layer draws a parabola in the thickness direction of the glass plate is obtained. Lose.

More specifically, the tensile stress value of the glass plate obtained by the glass plate manufacturing method of this embodiment is substantially constant in the thickness direction of a glass plate, and the maximum value of the tensile stress value only quenchs a glass ribbon by a slow cooling process. It is smaller than the maximum tensile stress value of the tensile stress layer formed by. When a tensile stress value becomes extremely large, there exists a possibility that a glass plate may break at the time of a process, etc., and it is preferable that the tensile stress value is smaller. In addition, although the depth of the compressive stress layer formed only by quenching a glass ribbon by a slow cooling process is the thickness of 1/10 or more of the plate | board thickness of a glass plate normally, it is the thickness of the compressive stress layer formed by the glass plate manufacturing method of this embodiment. The depth is for example less than 1/13 of the plate thickness. That is, when the thickness of the plate becomes thin, the thickness of the tensile stress layer for canceling the compressive stress of the compressive stress layer on the glass plate also becomes thin. Therefore, the stress value of the tensile stress layer formed only by quenching the glass ribbon in the slow cooling process is It becomes large and, as a result, the processing precision of a glass plate falls. However, since the stress value of the tensile stress layer of the glass plate obtained by the glass plate manufacturing method of this embodiment is substantially constant in the thickness room of a glass plate, the maximum value of a tensile stress value also becomes small, and processing of a glass plate can also be performed with high precision. .

(4) Vickers hardness

The Vickers hardness of the surface of the glass plate obtained by the glass plate manufacturing method of this embodiment is larger than the Vickers hardness inside a glass plate. That is, since the Vickers hardness of the surface of the glass plate obtained by the glass plate manufacturing method of this embodiment improves, a crack incidence rate falls and it is hard to produce a scratch, and the effect that it is hard to damage can be acquired.

It is preferable that the Vickers hardness of the glass plate surface formed in this embodiment is 4 GPa or more, It is more preferable that it is 5 GPa or more, It is further more preferable that it is 5.35 GPa or more. Or 1.01 or more is preferable and, as for ratio of the Vickers hardness of the glass plate surface with respect to the Vickers hardness inside a glass plate, 1.02 or more (more 1.05 or more, 1.10 or more) are more preferable.

(5) plate thickness

It is preferable that the thickness of the glass plate obtained by the glass plate manufacturing method of this embodiment is 1.5 mm or less. When the thickness is 3 mm or more, the strength of the glass plate itself is increased, and the compressive stress layer formed near the surface does not exhibit sufficient effect. As for the thickness of a glass plate, it is more preferable that it is 1.0 mm or less (Moreover, 0.7 mm or less, 0.5 mm or less, 0.3 mm or less). The thinner the glass plate, the more significant the effect of the present invention is.

(6) the size of the glass plate

The glass plate manufacturing method of this embodiment is suitable for a large glass plate. This is because the larger the glass plate is, the larger the amount of warpage and the glass plate is more likely to be broken due to fine scratches caused by handling. However, the occurrence of the problem can be reduced by forming a compressive stress layer on the glass plate surface. For this reason, the glass plate manufacturing method of this embodiment is suitable for manufacture of the glass plate of 1000 mm or more and 2000 mm or more in width direction, for example.

In this embodiment, although the volatilization promotion process which accelerates the volatilization of the volatile component in the surface of the molten glass 3 and in some cases the surface of the molten glass 3 and the glass ribbon 4 immediately after formation is performed, In the volatilization promotion step of the invention, volatilization of the volatile components on at least one surface of the molten glass and the glass ribbon may be promoted. In order to realize this, the partial pressure of the volatile components (pressure of the volatile components when removing a gas other than the volatile components in the atmosphere) and the saturation of the volatile components in the atmosphere facing at least one surface of the molten glass and the glass ribbon. The difference with the vapor pressure may be increased. As an example, what is necessary is just to reduce the density | concentration of the volatile component in the atmosphere which faces at least one surface of a molten glass and a glass ribbon. In particular, in the case where the molding step is performed using the molding apparatus 1 in the heat insulating structure 2 as in the present embodiment, melting that flows down the gas introduced into the heat insulating structure 2 outside the heat insulating structure 2 is performed. After contacting the surface of the glass 3 and / or the glass ribbon 4 pulled, you may discharge it out of the heat insulation structure 2. As shown in FIG.

Next, the specific example of the shaping | molding unit comprised from the shaping | molding apparatus 1 and the heat insulation structure 2 is demonstrated in detail.

<1st embodiment>

FIG.2 and FIG.3 shows the shaping | molding unit 10A which is a part of glass plate manufacturing apparatus of 1st Embodiment. This molding unit 10A is for performing a volatilization promotion process by discharging the gas introduce | transduced in the heat insulation structure 2 from the heat insulation structure 2 outside from the heat insulation structure 2, and out. By introducing fresh air into the heat insulation structure 2 in this way, the density | concentration of the vaporized volatile component in the heat insulation structure 2 can be reduced, and volatilization of the volatile component from the surface of the molten glass 3 is thereby carried out. Can be promoted. This is because when the volatile component becomes saturated in the heat insulating structure 2, volatilization of the further volatile component becomes difficult to proceed. In particular, in this embodiment, gas flows along the surface of the molten glass 3 which flows down.

The shaping | molding apparatus 1 is made into the cross-sectional shape of the pentagram-shaped wedge shape (narrow groove base shape) which sharpens downward, the upper surface in which the groove 11 which extends linearly is provided, and the groove 11 in this upper surface. It has a pair of wall surface 12 facing down at both ends parallel to (). In the present specification, for convenience of description, the direction in which the grooves 11 extend on the horizontal plane is also referred to as the X direction, the direction orthogonal to the X direction on the horizontal plane is also referred to as the Y direction and the vertical direction as the Z direction (see FIG. 2).

The groove 11 is slightly shallower in depth toward the other end at one end so as to uniformly overflow the molten glass 3 supplied to one end from the supply pipe (not shown) over the entire length. Each of the pair of wall surfaces 12 comprises a vertical surface suspended vertically from an end in the Y direction of the upper surface, and an inclined surface inclined inward so as to be close to each other at the lower end of the vertical surface, and the lower ends of the inclined surfaces cross each other in the X direction. It forms an ridge that extends.

And the shaping | molding apparatus 1 overflows the molten glass 3 from the both sides of the groove | channel 11, guides and fuses the overflowed molten glass to the wall surface 12, and fuses | belt-shaped glass ribbon 4 Form continuously.

The heat insulation structure 2 forms the shaping | molding chamber which accommodates the shaping | molding apparatus 1. As shown in FIG. Specifically, the heat insulation structure 2 is comprised with the material excellent in heat insulation, and the bottom wall 21, the ceiling wall 23, and the bottom wall 21 which oppose each other across the shaping | molding apparatus 1 in an up-down direction are shown. And a rectangular cylindrical peripheral wall 22 connecting the peripheral edges of the ceiling wall 23 to each other. In the center of the bottom wall 21, the gate 25 which passes the glass ribbon 4 formed by the shaping | molding apparatus 1 is provided. In addition, the heat insulation structure 2 has a hollow structure, and the air for heating or cooling may be supplied inside.

In this embodiment, the some discharge port 26 which penetrates the said peripheral wall 22 in the upper part of the barrier part of the Y direction side facing the wall surface 12 of the shaping | molding apparatus 1 in the peripheral wall 22. As shown in FIG. Is provided, and a plurality of inlets 27 penetrating the peripheral wall 22 are provided below the barrier portion on the Y-direction side of the peripheral wall 22. For this reason, the flow of air as shown by arrows a, b, and c in FIG. 1 is formed by natural convection. That is, air outside the heat insulating structure 2 is introduced into the heat insulating structure 2 through the inlet port 27, and this air is along the molten glass 3 flowing down the wall surface 12 of the molding apparatus 1. Ascends and then exits the thermal insulation structure 2 through the outlet 26. In this way, by raising the fresh air taken in from the outside in the heat insulating structure 2, the concentration of the volatile component in the atmosphere facing the surface of the molten glass 3 is lowered and the volatile component becomes saturated. because it can be prevented, it is possible to promote the vaporization of the volatile components from the molten glass 3 (e.g. _{B 2 O 3, SnO, K} 2 O). In other words, since the difference between the partial pressure of the volatile component and the saturated vapor pressure of the volatile component in the atmosphere facing the surface of the molten glass 3 can be increased, volatilization of the volatile component on the surface of the molten glass 3 Can promote. The part which volatilized this volatile component, ie, the surface of the molten glass 3 which contacted the rising air, becomes a compressive stress layer when the glass ribbon 4 is cooled. In order to make the stress value of a compressive stress layer high, it is preferable that the molten glass 3 contains many volatile components.

In addition, the discharge port 26 and the introduction port 27 may be provided in the end wall part of the X direction side in the circumferential wall 22. Alternatively, the outlet port 26 and the inlet port 27 may be provided only at the end wall portion on the X-direction side of the peripheral wall 22. However, in order to volatilize a volatile component uniformly over the whole width | variety of the molten glass 3, the discharge port 26 and the inlet port 27 are provided only at the constant pitch on the barrier part of the Y-direction side of the surrounding wall 22, and It is desirable to have.

In addition, the shape and quantity of the discharge port 26 and the introduction port 27 can be suitably selected as long as the intensity | strength required for the peripheral wall 22 is maintained. For example, as shown in FIG. 2, the shape of the discharge port 26 and the introduction port 27 may be circular, and the number may be reduced as a slit shape extended in an X direction. For example, when making the discharge port 26 and the introduction port 27 circular, it is preferable that the diameter shall be 1-20 mm. It is because there exists a possibility that intensity | strength of the heat insulation structure 2 may become inadequate when diameter exceeds 20 mm. Moreover, in order to discharge gas from the heat insulation structure 2 uniformly and more effectively, it is more effective that the discharge port 26 is a slit extended over the whole width direction of a glass ribbon. However, as the opening area is expanded, the amount of air flow increases too much, causing an increase in surface defects of the glass plate, deterioration of surface irregularities of the glass plate, and difficulty in securing a molding temperature. However, as described below, the temperature of air or inert gas introduced into the heat insulating structure 2 from the inlet port 27 is set as the target temperature in the heat insulating structure 2, and the heat insulating structure 2 This can be solved by adjusting the flow rate so that the internal pressure can be maintained at a predetermined pressure.

Moreover, it is preferable that the air introduce | transduced into the heat insulation structure 2 through the inlet port 27 is temperature of the grade which does not reduce the temperature of the molten glass 3 and the glass ribbon 4, for example. Here, when the amount of air introduced is a small amount, even if air at room temperature is introduced, the temperature of the molten glass 3 and the glass ribbon 4 does not decrease by that much, so you may introduce air at room temperature. On the other hand, when the quantity of air introduced is large, when the air of normal temperature is introduce | transduced, the temperature of the molten glass 3 and the glass ribbon 4 will fall large. In this case, it is preferable to provide heating means for heating the air introduced through the introduction port 27 to a predetermined temperature outside or inside the heat insulating structure 2. When using a heating means, the temperature of air is substantially equivalent to the temperature of the molten glass 3 outside the heat insulation structure 2 (for example, in the range of +/- 10% of the temperature of a molten glass) or more temperature It is preferable to heat air so that it may become, and introduce this heated air into the heat insulation structure (2).

When 10 A of shaping | molding units of this embodiment demonstrated above are used, the heat insulating structure 2 will overflow the molten glass 3 in the both sides of the groove | channel 11 of the shaping | molding apparatus 1 surrounded by the heat insulating structure 2. After the air introduced into the heat insulating structure 2 from the outside is raised along the molten glass 3 flowing down on the wall surface 12 of the molding apparatus 1, a step of discharging the air out of the heat insulating structure 2 is performed. In this manner, the volatilization of the volatile components from the molten glass 3 can be effectively promoted by raising the gas passing through the heat insulating structure 2 along with the molten glass flowing down on the wall surface 12 of the molding apparatus 1. Can be. Thereby, the glass plate in which the compressive stress layer with a high stress value was formed in both main surfaces can be obtained.

In addition, although the discharge port 26 is provided in the upper part of the circumferential wall 22 in the said embodiment, the position of the discharge port 26 is not specifically limited. For example, like the shaping | molding unit 10C of the modification shown in FIG. 5, you may provide the discharge port 26 in the part immediately above the shaping | molding apparatus 1 in the ceiling wall 23. As shown in FIG. Even in this way, the air introduced into the heat insulation structure 2 from the outside of the heat insulation structure 2 by natural convection is raised along the molten glass 3 flowing down on the wall surface 12 of the molding apparatus 1. It can then be discharged out of the thermal insulation structure 2 via the outlet 26. In addition, in this case, when the molten glass 3 is provided in the upper part of the circumferential wall 22 in order to contact the air which passes through the heat insulation structure 2 also in the upper side of the shaping | molding apparatus 1, It is possible to further promote volatilization of the volatile component.

However, in the case where the outlet port 26 is provided on the ceiling wall 23 of the peripheral wall 22, falling objects on the upper side of the heat insulating structure 2 may fall on the molten glass 3 through the outlet port 26. There is. From this viewpoint, it is preferable to provide the discharge port 26 on the upper part of the peripheral wall 22 like the said embodiment.

In addition, although the inlet port 27 is provided in the lower part of the circumferential wall 22 in the said embodiment, the position of the inlet port 27 is not specifically limited. For example, like the molding unit 10B of the modification shown in FIG. 4, the introduction port 27 may be provided in the bottom wall 21. In this case, when the inlet port 27 is in the area | region R directly under the shaping | molding apparatus 1, since there exists a possibility that the flow of air from the inlet port 27 may affect the shape stability of the glass ribbon 4, The inlet port 27 is preferably provided outside the region R.

In addition, as shown in FIG. 5, the introduction port 27 can be omitted. Even in this manner, air outside the heat insulating structure 2 is introduced into the heat insulating structure 2 through the gate 25. Thereby, volatilization of a volatile component can also be accelerated | stimulated also from the surface of the glass ribbon 4 immediately after formation. In this case, however, the gas passes through the gate 25 in the opposite direction to the glass ribbon 4, and the shape stability of the glass ribbon 4 may be impaired. Therefore, the inlet port is separated from the gate 25. It is preferable to provide (27).

In addition, in the said embodiment, although the introduction of the air in the heat insulation structure 2 and discharge of the air out of the heat insulation structure 2 are made | formed by natural convection, it is also possible to perform these by forced convection. For example, the supply pipe may be allowed to pass through the lower part of the heat insulating structure 2, and the discharge pipe may be passed through the upper part of the heat insulating structure 2, and a fan may be connected to either of them. In this case, the ends of the supply pipe and the discharge pipe opening in the space in the heat insulating structure 2 constitute the inlet port and the outlet port, respectively.

By the way, when using forced convection, when the temperature of the air introduce | transduced in the heat insulation structure 2 is a temperature substantially equal to or more than the temperature of the molten glass 3, shaping | molding of the modification shown in FIG. 6, for example Like the unit 10D, the inlet port 27 is provided above the heat insulating structure 2, and the air introduced into the heat insulating structure 2 descends along the molten glass 3, from the gate 25. It may be discharged out of the heat insulating structure 2. However, if the gas flows up along the molten glass 3 to flow down, the volatilization of a volatile component can be promoted more remarkably by the counterflow formed by these.

In addition, the gas introduced into the heat insulation structure 2 through the inlet 27 or the gate 25 does not necessarily need to be air, but may be an inert gas. As an inert gas, it is preferable to use nitrogen especially from a viewpoint of preventing corrosion of the shaping | molding apparatus 1 and the heat insulation structure 2. Alternatively, the gas introduced into the heat insulating structure 2 may be a mixture of air and an inert gas.

&Lt; Second Embodiment >

Next, with reference to FIG. 7, the shaping | molding unit 10E which is a part of glass plate manufacturing apparatus of 2nd Embodiment is demonstrated. In addition, the same code | symbol is attached | subjected to the same component part as 1st Embodiment, and the description is abbreviate | omitted.

The shaping | molding unit 10E of this embodiment is for performing a volatilization promotion process in a formation process by depressurizing the inside of the heat insulation structure 2. Specifically, the suction opening 28 is provided in the heat insulation structure 2, and the vacuum pump 6 is connected to this suction opening 28. In addition, the number of the suction ports 28 and the vacuum pump 6 is not specifically limited, What is necessary is just one or more.

When the inside of the heat insulating structure 2 is excessively depressurized, a gas having a lower temperature than the inside of the heat insulating structure 2 is introduced from the gate 25 in a large amount, the glass is not uniform, and a variation occurs in the thickness of the glass. Distortion may occur. Therefore, it is preferable to depressurize the inside of the heat insulation structure 2 in the range of 1/10 or less of the pressure around the heat insulation structure 2. That is, when the air pressure in the heat insulating structure 2 is 1 atmosphere, it is preferable to reduce the upper limit as 0.9 atmosphere. According to this embodiment, the density | concentration of the volatile component in the atmosphere which faces the surface of the molten glass 3 and the glass ribbon 4 can be reduced. In other words, the difference between the partial pressure of the volatile component and the saturated vapor pressure of the volatile component in the atmosphere facing the surfaces of the molten glass 3 and the glass ribbon 4 can be increased. Moreover, since the energy required for volatilization of a volatile component falls by depressurizing the inside of the heat insulation structure 2, volatilization of a volatile component is accelerated | stimulated further.

&Lt; Other Embodiments >

The present invention can be applied not only to the overflow downdraw method but also to the slot downdraw method, for example. In this case, a volatilization promoting step of promoting volatilization of the volatile component on the surface of the glass ribbon 4 immediately after formation is performed.

In addition, the method for implementing this invention is not limited to the said embodiment, For example, a volatilization promotion process can also be performed after a formation process by lengthening the time which keeps the glass ribbon 4 at high temperature.

<Examples>

Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not restrict | limited to these Examples at all.

As shown in Figs. 2 and 3, by using a molding unit 10A having a heat insulating structure 2 provided with an outlet 26 and an inlet 27, a size of 1100 mm x 1300 mm and a thickness of 0.7 mm Five glass plates were prepared (Examples 1 to 5).

The content rate of each component of the molten glass was as follows.

SiO ₂ : 60.9%

Al ₂ O ₃ : 16.9%

B ₂ O ₃ : 11.6%

MgO: 1.7%

CaO: 5.1%

SrO: 2.6%

BaO: 0.7%

K ₂ O: 0.25%

SnO ₂ : 0.13%

In addition, two discharge ports 26 were formed in a circular shape having a diameter of 10 mm in the upper portion of each end wall portion on the X-direction side of the peripheral wall 22. Two inlets 27 were formed in a circular shape having a diameter of 10 mm at the bottom of each end wall portion on the X-direction side of the peripheral wall 22.

(exam)

About the glass plate of the Example, the atomic concentration of the surface vicinity was measured using the X-ray photoelectron spectroscopy apparatus (Quantera SXM by Albacpai company). Specifically, the surface of the glass plate was excavated to various depths by sputtering, and the atomic concentration at each depth was measured. As a measurement element, Al, B, Ca, Sr, and Ba which are volatile components with a relatively high content rate were specified simultaneously with Si, and the ratio of Si which occupies in a measurement element was calculated | required. Among them, the results of Examples 1 and 2 were as shown in FIG. In addition, since the content rate of K and Sn is small among these volatile components, and it is thought that the influence which these amounts have on the ratio of Si is not considered, these were not included in the measurement element.

As can be seen from FIG. 8, in the examples, the Si ratio is higher than that inside the glass plate in a region extremely close to the surface. This indicates that the volatile components near the surface are decreasing, and it can be seen that by using a heat-insulating structure through which gas passes from the bottom, more volatile components can be volatilized to form a compressive stress layer having a high stress value. have.

In addition, the internal stress was measured about the glass plate of the Example. The internal stress is obtained by using a small area birefringence meter (KOBRA-CCD / X manufactured by Oji Keisukuki Co., Ltd.), and the optical path difference per 1 cm for each predetermined depth on the surface of the cross section obtained by cutting the glass plate in the thickness direction ( Optical path difference / optical path length) was measured and calculated by dividing this by the photoelastic constant. The result of Example 1 is as showing in FIG.

In FIG. 9, it turns out that the compressive stress layer with a high stress value is formed in the both main surfaces of a glass plate. In addition, the stress value of the tensile stress formed in the glass plate became substantially constant in the glass plate thickness direction. This is attributable to the decrease in volatile components near both main surfaces of the glass plate.

In Table 1, various original values regarding the glass plates of Examples 1-5 are shown.

In addition, "reference value" in a table | surface is "Si atom content in the glass composition of the center of the thickness direction of a glass plate" as mentioned above.

Next, the scratch test was done about the glass plates of Examples 1-5. Specifically, the scratch test was carried out by using a scratch hardness tester Model 318S manufactured by Eric Clean Corporation having a carbide ball chip having a diameter of 0.75 mm at the tip, and a scratch load of 2 N and a scratch length of 30 mm. As a result of observing the surface of the glass plate with a laser microscope, in Examples 1 to 5, no crack was generated on the surface of the glass plate. On the other hand, when the same scratch test was performed after polishing the surface of the glass plate of Example 1, the crack generate | occur | produced in the grinding | polishing surface.

Industrial Applicability

 This invention is especially preferable for manufacture of the plate glass for FPD glass substrates. Moreover, the tempered glass which chemically strengthened the glass plate obtained by this invention is used suitably for the cover glass of a mobile telephone, a digital camera, a PDA (portable terminal), a solar cell, and an FPD, In addition, for example, a touch panel display Can be expected to be used as a substrate, a window glass, a substrate for a magnetic disk, a cover glass for a solid-state image sensor, a tableware, and the like.

Claims (11)

A melting step of melting the glass raw material to obtain a molten glass,
A molding step of forming a glass ribbon from the molten glass by a downdraw method;
A volatilization promoting step of promoting volatilization of a volatile component from at least one surface of the molten glass and the glass ribbon;
A slow cooling process of cooling the glass ribbon,
Cutting step of cutting the glass ribbon to obtain a glass plate
/ RTI &gt;
In the said volatilization promotion process, the density | concentration of the said volatile component in the atmosphere which faces the at least one surface of the said molten glass and the said glass ribbon reduces the density | concentration of the volatile component from the at least one surface of the said molten glass and the said glass ribbon. Glass plate manufacturing method for promoting volatilization. A melting step of melting the glass raw material to obtain a molten glass,
A molding step of forming a glass ribbon from the molten glass by a downdraw method;
A volatilization promoting step of promoting volatilization of a volatile component from at least one surface of the molten glass and the glass ribbon;
A slow cooling process of cooling the glass ribbon,
Cutting step of cutting the glass ribbon to obtain a glass plate
/ RTI &gt;
The molding step is performed using a molding apparatus in the heat insulating structure,
In the volatilization promoting step, after the gas introduced into the heat insulating structure from outside the heat insulating structure is brought into contact with the surface of the flowing molten glass, the drawn glass ribbon, or both, the gas is discharged out of the heat insulating structure. And the glass plate manufacturing method of promoting volatilization of the volatile component from the at least one surface of the said molten glass and the said glass ribbon. The method of manufacturing a glass plate according to claim 2, wherein the glass plate is raised along a surface of the molten glass flowing down the gas, the glass ribbon drawn, or both. The method of claim 2, wherein the gas is air, an inert gas, or a mixture thereof. A melting step of melting the glass raw material to obtain a molten glass,
A molding step of forming a glass ribbon from the molten glass by a downdraw method;
A volatilization promoting step of promoting volatilization of a volatile component from at least one surface of the molten glass and the glass ribbon;
A slow cooling process of cooling the glass ribbon,
Cutting step of cutting the glass ribbon to obtain a glass plate
/ RTI &gt;
The said molding process is performed using the shaping | molding apparatus in a heat insulation structure,
In the volatilization promotion step, the glass plate manufacturing method which accelerates volatilization of the volatile component from the at least one surface of the said molten glass and the said glass ribbon by depressurizing the inside of the said heat insulation structure. A molding apparatus which overflows the molten glass from both sides of the groove and induces the overflowed molten glass on the wall to form a glass ribbon;
A heat insulating structure surrounding the molding apparatus and having a gate for passing the glass ribbon formed by the molding apparatus,
In order to promote volatilization of the volatile component from the surface of the said molten glass, the said heat insulating structure introduce | transduces the gas which rose in the said heat insulating structure from the outside of the said heat insulating structure, and rose along the molten glass which flows down on the wall surface of the said shaping | molding apparatus. Glass plate manufacturing apparatus provided with the discharge port discharged out of the heat insulating structure. The said heat insulation structure has a bottom wall provided with the said gate, the ceiling wall which opposes the said bottom wall by interposing the said shaping | molding apparatus, and the peripheral wall which connects the peripheral part of the said bottom wall and the said ceiling wall,
The said discharge port is a glass plate manufacturing apparatus provided in the upper part of the said peripheral wall. The glass plate manufacturing apparatus of Claim 7 with which the inlet which introduce | transduces the said gas in the said heat insulation structure is provided in the lower part of the said peripheral wall. The glass plate manufacturing apparatus according to any one of claims 6 to 8, wherein the gas is air, an inert gas, or a mixture thereof. delete delete

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