KR102080003B1 - Method for producing glass plate, and glass plate - Google Patents

Abstract

This invention provides the manufacturing method of the glass plate with the favorable quality of the main surface which contacted the reducing atmosphere in the bath. The present invention provides a method for producing a glass plate having a step of flowing molten glass continuously supplied on molten tin in a float bath by forming it on the molten tin, wherein the molten glass immediately before being supplied into the float bath is formed of Au, which is an impurity. The total content of Cu and Ag is 0.5 mass ppm or less, and the manufacturing method of the glass plate characterized by the above-mentioned.

Description

Method for manufacturing glass plate and glass plate {METHOD FOR PRODUCING GLASS PLATE, AND GLASS PLATE}

The present invention relates to a method for producing a glass plate and a glass plate.

The float method is widely used as a shaping | molding method of a glass plate. In the float method, molten glass continuously supplied on molten tin in a float bath (hereinafter also referred to simply as "bath") is flowed on molten tin to be molded into a strip shape (see Patent Document 1, for example). The atmosphere in the bath becomes a reducing atmosphere containing hydrogen gas in order to prevent oxidation of molten tin. Hydrogen gas reacts with oxygen gas mixed from the outside to prevent oxidation of molten tin.

Japanese Patent Laid-Open No. 2010-053032

When shaping the molten glass in the bath, the particles in the reducing atmosphere agglomerated and fell on the upper surface of the molten glass, which sometimes adhered and became a defect.

This invention is made | formed in view of the said subject, and an object of this invention is to provide the manufacturing method and glass plate of the favorable glass plate of the quality of the main surface which contacted the reducing atmosphere in the bath.

In order to solve the said objective, the manufacturing method of the glass plate which concerns on the form (1) of this invention,

In the manufacturing method of the glass plate which has a process of flowing and shape | molding the molten glass continuously supplied on the molten tin in a float bath on the said molten tin,

The molten glass immediately before being supplied into the float bath is characterized in that the total content of Au, Cu, and Ag as impurities is 0.5 mass ppm or less.

In addition, the manufacturing method of the glass plate which concerns on the form (2) of this invention,

In the manufacturing method of the glass plate which has a process of flowing and shape | molding the molten glass continuously supplied on the molten tin in a float bath on the said molten tin,

The molten glass immediately before being supplied into the float bath has a total content of F, Cl, Br, and I as impurities, which is 200 mass ppm or less.

In addition, the glass plate concerning the aspect (3) of this invention,

A glass plate which is formed by flowing molten glass continuously supplied on molten tin in a float bath on the molten tin,

The total content of Au, Cu and Ag as impurities is characterized by being 0.5 mass ppm or less.

In addition, the glass plate concerning the aspect (4) of this invention,

A glass plate which is formed by flowing molten glass continuously supplied on molten tin in a float bath on the molten tin,

It is characterized by the total content of impurities F, Cl, Br and I being 200 mass ppm or less.

According to this invention, the manufacturing method and glass plate of the glass plate with favorable quality of the main surface which contacted the reducing atmosphere in the bath are provided.

1: is explanatory drawing (1) of the manufacturing apparatus of the glass plate which concerns on one Embodiment of this invention.
It is explanatory drawing (2) of the manufacturing apparatus of the glass plate which concerns on one Embodiment of this invention.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated with reference to drawings. In addition, in the following drawings, the same or corresponding structure is attached | subjected with the same or corresponding code | symbol, and description is abbreviate | omitted.

The manufacturing method of the glass plate which concerns on this embodiment has a melting process, a shaping | molding process, a slow cooling process, and a cutting process, for example, and also has a grinding | polishing process as needed. Polishing process is performed according to the use of a glass plate.

A melting process melt | dissolves the glass raw material which mixed and manufactured several types of raw materials, and obtains a molten glass. After inject | pouring a glass raw material into a melting furnace, it melts by the radiant heat of the flame sprayed from a burner, and becomes molten glass.

The shaping | molding process continuously supplies the molten glass obtained by a melting process on the molten tin in a bath, flows a molten glass on molten tin, and shapes it, and obtains a plate-shaped glass (so-called glass ribbon). This molding method is called a float method. The atmosphere in the bath becomes a reducing atmosphere containing hydrogen gas in order to prevent oxidation of molten tin. The plate-like glass is cooled while flowing in a predetermined direction, and is pulled out of the molten tin near the outlet of the bath.

The slow cooling process slows down the plate glass obtained by a shaping | molding process in a slow cooling furnace. The plate glass is slowly cooled while being conveyed horizontally from the inlet of the slow cooling furnace toward the outlet. Sulfurous acid (SO ₂ ) gas or the like is injected onto the surface of the plate-like glass near the inner side of the inlet of the slow cooling furnace to form a scratch prevention film on the surface layer of the plate-shaped glass. Since the exit of the slow cooling furnace is open to the atmosphere, the atmosphere in the slow cooling furnace is an atmospheric atmosphere.

The cutting process cuts the plate glass cooled by the slow cooling process to predetermined dimension with a cutter. In a cutting process, the width direction both edge part (so-called ear | edge part) of plate-shaped glass is excised. This is because both edge portions in the width direction of the plate-shaped glass become thick under the influence of surface tension and the like.

The polishing step polishes the main surface of the glass plate obtained in the cutting step. In the grinding | polishing process, the main surface (henceforth "bottom surface") which contacted molten tin in the bath according to the use of a glass plate is polished. It is a main surface opposite to a bottom surface, and the main surface (henceforth "top surface") which contacted the reducing atmosphere in the bath is not polished.

In this way, the glass plate which is a product is obtained. The glass plate is used, for example, as a window glass for a vehicle, a window glass for a building, a substrate for a display, a cover glass for a display, or a substrate for a photomask. "Display" includes flat panel displays (FPD) such as liquid crystal displays (LCDs), plasma displays (PDPs), organic EL displays, and the like. As thickness of the display substrate, 1 mm or less is illustrated. Moreover, it is preferable that the thickness of the glass plate used for flexible liquid crystal panels, such as a tablet terminal, is 0.3 mm or less.

The kind of glass of a glass plate is selected according to the use of a glass plate. For example, in the case of the glass substrate for LCD, an alkali free glass is used. In addition, in the case of the vehicle window glass, the building window glass, and the glass substrate for PDP, soda-lime glass is used. In the case of cover glass for displays, chemically strengthenable soda lime glass is mainly used. In the case of a photomask substrate, quartz glass with a low thermal expansion coefficient is mainly used.

The alkali free glass is, for example, in terms of mass% based on an oxide basis, SiO ₂ : 50 to 66%, Al ₂ O ₃ : 10.5 to 24%, B ₂ O ₃ : 0 to 12%, MgO: 0 to 8% , CaO: 0 to 14.5%, SrO: 0 to 24%, BaO: 0 to 13.5%, ZrO ₂ : 0 to 5%, SnO: 0 to 3%, MgO + CaO + SrO + BaO: 9 to It is 29.5%, and the total amount of content of an alkali metal oxide may be 0.1% or less.

A non-alkali glass is preferably displayed in oxide-based mass%, SiO _2: 58 to _{66%, Al 2 O 3:} 15 to _{22%, B 2 O 3:} 5 to 12%, MgO: 0 to 8% , CaO: 0 to 9%, SrO: 3 to 12.5%, BaO: 0 to 2%, SnO: 0 to 1%, MgO + CaO + SrO + BaO: 9 to 18%, the alkali metal oxide The total amount of the content is 0.1% or less.

Soda-lime glass, for example in weight percentages of the oxide basis, SiO _2: 65 to _{75%, Al 2 O 3:} 0 to 3%, CaO: 5 to 15%, MgO: 0 to 15%, Na ₂ O: 10 to 20%, K ₂ O: 0 to 3%, Li ₂ O: 0 to 5%, Fe ₂ O ₃ : 0 to 3%, TiO ₂ : 0 to 5%, CeO ₂ : 0 to 3% , BaO: 0 to 5%, SrO: 0 to 5%, B ₂ O ₃ : 0 to 5%, ZnO: 0 to 5%, ZrO ₂ : 0 to 5%, SnO ₂ : 0 to 3%, SO ₃ : 0 to 0.5% is contained.

Next, based on FIG. 1 and FIG. 2, the detail of the shaping | molding process of the said glass plate is demonstrated.

1 and 2 are explanatory diagrams of an apparatus for manufacturing a glass plate according to an embodiment of the present invention. 1 is a plan sectional view of the bath, and FIG. 2 is a side sectional view of the bath.

In the molding step, the molten glass 30 is cooled while flowing on the molten tin 20 in the bath 10 to be molded into a strip shape. In order to prevent oxidation of the molten tin 20, the upper space in the bath 10 is filled with a reducing atmosphere 40 containing hydrogen gas. In order to prevent intrusion of outside air, the upper space in the bath 10 is maintained at a static pressure higher than atmospheric pressure. The bath 10 is provided with a spout lip 50, a heater 60, an air supply path 70, an exhaust path 80, and the like.

The spout lip 50 is a supply path for supplying the molten glass 30 into the bath 10, and is provided at the inlet 12 of the bath 10. The spout lip 50 is connected to a melting furnace for producing the molten glass 30.

The heater 60 heats the inside of the bath 10, and is suspended from the ceiling of the bath 10, for example, as shown in FIG. The heater 60 is provided in multiple numbers at intervals, for example in the flow direction (X direction) and the width direction (Y direction) of the molten glass 30, and is arrange | positioned in matrix form. The X direction and the Y direction are horizontal directions perpendicular to each other.

The output of the heater 60 is controlled such that the temperature of the molten glass 30 is lowered from the inlet 12 of the bath 10 toward the outlet 14. In addition, the output of the heater 60 is controlled so that the thickness of the molten glass 30 may become uniform in the width direction (Y direction).

The air supply passage 70 is a passage for supplying a reducing gas into the bath 10, and is installed on the ceiling of the bath 10, for example, as shown in FIG. 2. The air supply 70 is provided in plural at intervals in a predetermined direction (X direction).

The reducing gas may be a mixed gas of hydrogen gas and nitrogen gas. The proportion of hydrogen gas in the reducing gas is, for example, 0.1 to 15% by volume.

The exhaust path 80 is a passage through which the reducing atmosphere 40 is exhausted, and is provided on the side wall of the bath 10, for example, as shown in FIG. 2. A plurality of exhaust passages 80 are provided at intervals in a predetermined direction (X direction).

As shown in FIG. 2, the plate-shaped glass (so-called glass ribbon) which shape | molded the molten glass 30 to strip shape is pulled up from the molten tin 20 in the vicinity of the exit 14 of the bath 10. As shown in FIG. Thereafter, the plate-shaped glass is a glass plate which is a product through a slow cooling process, a cutting process, and the like.

By the way, the reducing atmosphere 40 in the bath 10 contains the component volatilized from the molten tin 20 and the molten glass 30 in addition to the reducing gas supplied from the air supply 70. Among the components (including single particles and compounds) volatilized from the molten tin 20 and the molten glass 30 into the reducing atmosphere 40, the components having low vapor pressure are difficult to volatilize originally and are not a problem because they are small. On the other hand, a component having a high vapor pressure is usually not a problem because it is discharged to the outside of the bath 10 as a gas. However, the component having a low vapor pressure becomes vaporizable when the specific compound (for example, halide) becomes high, but volatilizes once, and once volatilized, it is immediately reduced by hydrogen gas in the reducing atmosphere 40. As a result, the atmosphere In some cases, the original vapor pressure may be returned to a low component. Then, since the component with low vapor pressure hardly exists as a gas, it may become an aggregate in the reducing atmosphere 40, and may fall on the molten glass 30, and may become a fault. As an element, the element of Group 11, such as Au, Cu, Ag, is mentioned as an element which is low in vapor pressure and tends to be a halide. Since the Group 11 element has the same constitution of the home appliance as the alkali metal element, easily becomes monovalent ions, and easily becomes a halide, the reducing atmosphere 40 is reduced from the molten tin 20 or the molten glass 30 as a halide. It is easy to volatilize. In addition, when Au, Cu, and Ag become monovalent ions, they are easily diffused in the molten tin 20 and the molten glass 30, and are easily moved to the interface with the reducing atmosphere 40, and therefore, volatilized in the reducing atmosphere 40. Easy to be When gold halides, copper halides, and silver halides in the reducing atmosphere 40 are reduced by hydrogen gas, Au, Cu, and Ag having low original vapor pressures are generated. Since Au, Cu, and Ag are hardly present as gases as a single substance, they form aggregates in the reducing atmosphere 40. This aggregate contains at least one element of Au, Cu, and Ag, and may further contain elements other than Au, Cu, and Ag.

In this embodiment, in the molten glass 30 immediately before supplying in the bath 10, the total content of Au, Cu, and Ag (henceforth generically called "Au etc.") as an impurity is 0.5 mass ppm or less. When total content, such as Au, is 0.5 mass ppm or less, there are few components in the molten glass 30 which volatilizes from the molten glass 30 to the reducing atmosphere 40, and becomes an aggregate. Therefore, it becomes difficult for aggregate to grow in the reducing atmosphere 40, and it becomes difficult for an aggregate to fall to the upper surface of the molten glass 30. FIG. Therefore, the quality of the top surface of a glass plate becomes favorable. The more preferable range is 0.3 mass ppm or less, and still more preferable range is 0.1 mass ppm or less.

The total content of Au and the like in the molten glass 30 immediately before feeding into the bath 10 is slightly smaller than the total content of Au and the like in the glass raw material to be introduced into the melting furnace. This is because Au and the like are gradually volatilized from the glass to the outside in the dissolution step.

Therefore, it is preferable that the total content of Au etc. in glass raw material is 1.0 mass ppm or less so that the total content of Au etc. in the molten glass 30 immediately before supplying into the bath 10 will be 0.5 mass ppm or less. The more preferable range is 0.5 mass ppm or less, and still more preferable range is 0.3 mass ppm or less.

In addition, in this embodiment, in the molten glass 30 immediately before supplying in the bath 10, the total content of F, Cl, Br, and I (henceforth collectively called "F") as an impurity is 200 mass. ppm or less. F and the like have a boiling point lower than the forming temperature of the glass, and promote volatilization of Au and the like.

When the total content of F and the like in the molten glass 30 immediately before being supplied into the bath 10 is 200 mass ppm or less, Au and the like in the molten glass 30 are hardly volatilized in the reducing atmosphere 40. It is difficult for the aggregate to grow in 40), and the aggregate becomes difficult to fall. Therefore, the quality of the top surface of a glass plate becomes favorable. The more preferable range is 100 mass ppm or less, and still more preferable range is 50 mass ppm or less.

The total content of F and the like in the molten glass 30 immediately before feeding into the bath 10 is slightly smaller than the total content of F and the like in the glass raw material to be introduced into the melting furnace. This is because F and the like are gradually volatilized from the glass to the outside in the dissolution step.

Therefore, it is preferable that the total content of F etc. in glass raw material is 500 mass ppm or less so that the total content of F etc. in the molten glass 30 immediately before supplying into the bath 10 will be 200 mass ppm or less. The more preferable range is 300 mass ppm or less, and still more preferable range is 200 mass ppm or less.

The molten tin 20 in the bath 10 may have a total content of Au, such as impurities, of 10 mass ppm or less, and a total content of F, such as 100 mass ppm or less, due to high quality of the top surface. As a raw material of the molten tin 20 in the bath 10, tin is used, for example.

Next, the glass plate obtained by the said manufacturing method is demonstrated.

The glass plate is 0.5 mass ppm or less in total content, such as Au. Au and the like are volatilized from the glass to the outside in the forming step and the slow cooling step, but the amount of volatilization is very small compared to the total amount. The glass composition of the glass plate and the glass composition of the molten glass 30 in a shaping | molding process are substantially the same. When the total content of Au and the like in the glass plate is 0.5 mass ppm or less, the total content of Au and the like in the molten glass 30 in the forming step is small, and the molten glass 30 is reduced from the molten glass 30 to the reducing atmosphere 40. There is little component which volatilizes and becomes nucleus of aggregate. Therefore, it becomes difficult for an aggregate to grow, and it becomes difficult for an aggregate to fall to the upper surface of the molten glass 30. FIG. Therefore, the quality of the top surface of a glass plate becomes favorable.

In addition, as for a glass plate, the total content, such as F, is 200 mass ppm or less. F and the like are volatilized from the glass to the outside in the forming step and the slow cooling step, but the amount of volatilization is not much compared with the total amount. The glass composition of the glass plate and the glass composition of the molten glass 30 in a shaping | molding process are substantially the same. When content of F etc. in a glass plate is 200 mass ppm or less, since content of F etc. in the molten glass 30 in a shaping | molding process is small, it is difficult for Au etc. in the molten glass 30 to volatilize to the reducing atmosphere 40, In the reducing atmosphere 40, the aggregate is difficult to grow, and the aggregate is difficult to fall. Therefore, the quality of the top surface of a glass plate becomes favorable.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment. Various modifications and substitutions can be made to the above embodiments without departing from the scope of the invention.

For example, in the molten glass 30 of the said embodiment, just before supplying in the bath 10, (1) total content, such as Au, is 0.5 mass ppm or less, and (2) F, etc. Although it is 200 mass ppm or less, you may satisfy | fill only (1) or (2). This is because the deposit on the top surface occurs when both impurities such as Au and impurities such as F are too large. The same applies to impurities in the molten tin 20 in the bath 10.

Moreover, although the total content of (1) Au etc. is 0.5 mass ppm or less, and the total content, such as (2) F, is 200 mass ppm or less, the glass plate of the said embodiment may satisfy only (1) or (2). do.

<Example>

Hereinafter, although an Example etc. demonstrate this invention concretely, this invention is not limited by these examples.

Example 1

In Example 1, the glass plate containing an alkali free glass was manufactured by the method shown in FIG. 1 and FIG. Tin was used as a raw material of molten tin in the bath. A non-alkali glass, the display of the oxide-based _{mass%, SiO 2: 59.5%,} Al 2 O 3: 17%, B 2 O 3: 8%, MgO: 3.3%, CaO: 4%, SrO: 7.6%, BaO: 0.1%, ZrO _2: 0.1%, containing, and MgO + CaO + SrO + BaO to 15%, and a balance being inevitable impurities, was 0.1% or less of the amount of the sum of the content of alkali metal oxides.

The content (mass%) of each element (including Au, F, etc.) contained in the glass raw material, the molten glass just before feeding in a bath, and a glass plate was measured by the wet analysis. In the wet analysis, samples such as glass raw materials were dissolved in an acid and analyzed. In addition, the sample of the molten glass immediately before supplying in a bath was quenched and produced, after pouring the molten glass near the inlet of a bath with the iron ladle sufficiently cooled.

The average density (piece / m <^2> ) of the deposit | attachment of the top surface of a glass plate observed 40 glass plates with 1.0 m * 1.0m of top surfaces, and measured them.

Table 1 shows the measurement results of the total content of Au and the like, the total content of F and the like and the average density of the deposits.

[Examples 2 to 6]

In Examples 2 to 6, a glass plate was produced in the same manner as in Example 1 except that a small amount of equimolar amounts of CuO and Ag ₂ S were added to the glass raw material. Examples 1 to 4 are Examples, and Examples 5 to 6 are Comparative Examples.

The total content of Au and the like, the total content of F and the like and the average density of the deposit were measured in the same manner as in Example 1. Table 1 shows the measurement results.

From Table 1, it can be seen that in the molten glass or glass plate immediately before feeding into the bath, if the total content of Au or the like is 0.5 mass ppm or less, there are significantly fewer defects in the deposit.

Example 7

In Example 7, the glass plate containing an alkali free glass was produced like Example 1 except having changed the glass raw material. A non-alkali glass, the display of the oxide-based _{mass%, SiO 2: 59.5%,} Al 2 O 3: 17%, B 2 O 3: 8%, MgO: 3.3%, CaO: 4%, SrO: 7.6%, BaO: 0.1%, ZrO _2: 0.1%, containing, and MgO + CaO + SrO + BaO to 15%, and a balance being inevitable impurities, was 0.1% or less of the amount of the sum of the content of alkali metal oxides.

The total content of Au and the like, the total content of F and the like and the average density of the deposit were measured in the same manner as in Example 1. Table 2 shows the measurement results.

[Examples 8 to 12]

Example 8 to example 12 were prepared in the same manner as the glass plate except for the addition of trace amounts of CaF _2, Example 7, a glass raw material. Examples 7 to 10 are Examples, and Examples 11 to 12 are Comparative Examples.

The total content of Au and the like, the total content of F and the like and the average density of the deposit were measured in the same manner as in Example 1. Table 2 shows the measurement results.

From the molten glass and glass plate just before supplying in a bath from Table 2, it turns out that the defect of a deposit is significantly small when total content, such as F, is 200 mass ppm or less.

From the molten glass or glass plate immediately before supplying in a bath from Table 1 and Table 2, if the total content of Au etc. is 0.5 mass ppm or less, and if the total content of F etc. is 200 mass ppm or less, the defect of a deposit will become small enough. Able to know.

This application is based on the JP Patent application 2012-159048 of an application on July 17, 2012, The content is taken in here as a reference.

10: bass
12: Entrance to Bath
14: exit of bath
20: molten tin
30: molten glass
40: reducing atmosphere
50: Spout Lip
60: heater
70: with air supply
80: exhaust furnace

Claims (11)

In the manufacturing method of the glass plate which has a process of flowing and shape | molding the molten glass continuously supplied on the molten tin in a float bath on the said molten tin,
The glass plate is an alkali free glass,
The molten glass immediately before being supplied into the float bath has a total content of Au, Cu, and Ag as impurity of 0.05 mass ppm or more and 0.5 mass ppm or less. The said molten glass immediately before being supplied to the said float bath is a manufacturing method of the glass plate of Claim 1 whose total content of F, Cl, Br, and I which are impurities is 200 mass ppm or less. The method of claim 2,
The said molten glass immediately before being supplied into the said float bath is a manufacturing method of the glass plate whose total content of F, Cl, Br, and I which are impurities is 20 mass ppm or more. A glass plate which is formed by flowing molten glass continuously supplied on molten tin in a float bath on the molten tin,
The glass plate is an alkali free glass,
A total glass content of Au, Cu and Ag as impurities is 0.05 mass ppm or more and 0.5 mass ppm or less. The glass plate of Claim 4 whose total content of F, Cl, Br, and I which are impurities is 200 mass ppm or less. The method of claim 5,
The glass plate whose total content of impurities F, Cl, Br, and I is 20 mass ppm or more. delete The glass plate according to any one of claims 4 to 6, wherein the glass plate is a glass substrate for a display. The glass plate of Claim 8 whose thickness of the said glass plate is 1 mm or less. The method of claim 4 according to any one of claim 6, wherein the glass sheet, the oxide basis in% by mass shown, SiO _2: 50 to _{66%, Al 2 O 3:} 10.5 to _{24%, B 2 O 3:} 0 To 12%, MgO: 0 to 8%, CaO: 0 to 14.5%, SrO: 0 to 24%, BaO: 0 to 13.5%, ZrO ₂ : 0 to 5%, SnO: 0 to 3%, MgO + CaO + SrO + BaO: It is 9-29.5%, The glass plate which is an alkali free glass whose content of alkali metal oxide is 0.1% or less. Article according to any one of the preceding claims, with the glass plate, the display of the oxide-based mass%, SiO _2: 58 to _{66%, Al 2 O 3:} 15 to _{22%, B 2 O 3:} 5 To 12%, MgO: 0 to 8%, CaO: 0 to 9%, SrO: 3 to 12.5%, BaO: 0 to 2%, SnO: 0 to 1%, MgO + CaO + SrO + BaO: It is 9 to 18%, and the glass plate which is an alkali free glass whose total amount of content of an alkali metal oxide is 0.1% or less.

Images