JP2015051889A - Granulated body, method for manufacturing the same, method for manufacturing glass article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel method for manufacturing a glass raw material molded body which can be used as a raw material of non-alkali glass.SOLUTION: There is provided a manufacturing method of granulated body by mixing a glass raw material composition and water, in which the glass raw material composition is used in manufacture of non-alkali glass having an aluminum source containing aluminate expressed by a formula xRO AlO(note that x denotes 1 to 3, and R is either one or both of Sr and Ba) and a silicon source as essential components.

Description

  The present invention relates to a granulated body used for the production of alkali-free glass, a method for producing the same, and a method for producing a glass article using the granulated body.

Various display glass substrates are required to be alkali-free glass substantially free of alkali metal oxides. The alkali-free glass used for the display substrate requires melting at a high temperature as compared with general soda lime glass. This is due to the fact that a high melting point silica raw material is used in a large amount and that an alkali component having an action of accelerating the melting of the silica raw material is not used.
Further, the glass substrate for display is required to have high quality such as absence of bubbles, striae, undissolved matter, pits, scratches, etc., which are defects that affect the display on the inside and surface of the glass substrate. However, the alkali-free glass used for the display substrate tends to be less likely to have a uniform glass composition than general soda lime glass. In order to obtain a glass having a high uniformity of glass composition, it is effective to atomize the glass raw material so as not to leave an unmelted raw material. However, when using atomized glass raw materials, the glass raw materials are likely to be scattered when the raw materials are put into the glass melting furnace, so that the glass composition becomes unstable and a part of the glass raw materials is wasted. Such problems arise.

As a method for solving the problem that the atomized glass raw material is scattered, a method using a glass raw material as a granulated body is known. For example, Patent Document 1 describes a method for producing a granulated body using caustic soda or water glass as a binder. Patent Document 2 describes a method for producing a granulated body using boric acid as a binder. Patent Document 3 describes a method for producing glass fibers using Portland cement or alumina cement as a main glass material (Example 1). Regarding the composition of the alumina cement, SiO ₂ is 3 to 6% by mass, Al ₂ O ₃ is 49 to 57% by mass, Fe ₂ O ₃ is 0.3 to ₃ % by mass, CaO is 35 to 40% by mass, and MgO is It is described as 0 to 1% by mass.

Japanese Unexamined Patent Publication No. 64-51333 International Publication No. 2012/039327 Japanese Patent Laid-Open No. 49-19130

However, when granulating a non-alkali glass raw material, caustic soda or water glass containing an alkali metal cannot be used as a binder, so it is difficult to obtain a strong granule that is not easily broken.
Recently, characteristics required for various display glass substrates are diversified, and alkali-free glass containing almost no boron oxide (B ₂ O ₃ ) has been demanded. However, when granulating a glass raw material for a glass having a low boron oxide content or a glass not containing boron oxide, it is difficult to obtain a strong granule that is hard to break using boric acid as a binder. .
In addition, the present inventors tried to granulate a glass raw material containing alumina cement, but could not form a strong granulated body that was not easily broken.

  This invention is invention which solves the said subject, and provides the manufacturing method of the granule which can be used for manufacture of an alkali free glass.

The present invention provides the following [1] to [15] for solving the above problems.
[1] A method for producing a granulated body by mixing a glass raw material composition and water, wherein the glass raw material composition is an aluminate represented by the formula xRO · Al ₂ O ₃ (where x is 1 to 3). And R is one or both of Sr and Ba.) A method for producing a granulated body used in the production of alkali-free glass containing an aluminum source and a silicon source.

[2] The method for producing a granulated product according to [1], wherein the glass raw material composition further contains one or both of calcium oxide and calcium hydroxide.
[3] The method for producing a granulated product according to [1] or [2], wherein the glass raw material composition further contains one or both of sulfate and nitrate.

[4] The method for producing a granulated product according to [1] to [3], wherein the silicon source is silica and the average particle size of silica is 2 to 150 μm.
[5] The method for producing a granulated product according to [1] to [4], wherein x in the formula xRO · Al ₂ O ₃ is 1.
[6] The glass raw material composition is 40 to 85% by mass of SiO ₂ , 5 to 30% by mass of Al ₂ O ₃ , MgO with respect to 100% by mass of the alkali-free glass obtained from the granulated body. Of 1 to 18 mass%, the total amount of CaO, SrO and BaO is 2 to 40 mass%, and the total amount of SrO and BaO is more than 0 mass% [1] to [5] .
[7] The method for producing a granulated product according to [1] to [6], wherein the granulated product is obtained by solidifying the glass raw material composition and water.
[8] The method for producing a granulated product according to [1] to [6], wherein the glass raw material composition and water are mixed and then compression molded to obtain a granulated product.
[9] The glass raw material composition substantially does not contain boric acid and boron oxide, or the total amount of boric acid and boron oxide is more than 0% by mass and 3% by mass or less with respect to 100% by mass of the glass raw material composition. [1] to [8] A method for producing a granulated product.

[10] A granulated body used for the production of a glass article made of alkali-free glass, wherein the granulated body requires a silicon source and an aluminum source, and the aluminum source is 3SrO · Al ₂ O ₃ · 6H ₂ O, _{3BaO · Al 2 O 3 · 6H} 2 O , and _{3SrO · Al 2 O 3 · 6H} 2 O and _{3BaO · Al 2 O 3 · 6H} 2 O solid solution, granulates is at least one selected from the.

[11] The granulated product according to [10], wherein the granulated product has an average particle diameter of 50 μm to 50 mm.
[12] The granulated product is 40 to 85% by mass of SiO ₂ , 5 to 30% by mass of Al ₂ O ₃ , and MgO with respect to 100% by mass of the alkali-free glass obtained from the granulated product. Granulation of [10] to [12] which is a granulated body containing 0 to 18% by mass, the total amount of CaO, SrO and BaO being 2 to 40% by mass and the total amount of SrO and BaO being more than 0% by mass body.
[13] A granulated body is obtained by the method for producing a granulated body of [1] to [9], the granulated body is heated to obtain a glass melt, and the glass melt is molded and gradually cooled. A glass article manufacturing method for obtaining a glass article.
[14] A method for producing a glass article, wherein the granulated product of [10] to [12] is heated to obtain a glass melt, the glass melt is shaped and slowly cooled to obtain a glass article.
[15] A glass article made of alkali-free glass is 40 to 85 mass% of SiO ₂ , 5 to 30 mass% of Al ₂ O ₃ , and 0 to 18 of MgO in terms of oxide with respect to 100 mass% of the glass article. [13] or [14], wherein the total amount of CaO, SrO, and BaO is 2 to 40% by mass and the total amount of SrO and BaO is more than 0% by mass.

According to the method for producing a granulated body of the present invention, a strong granulated body that is difficult to break can be produced.
The granulated body of this invention can be used as a granulated body used for manufacture of an alkali free glass.
According to the method for producing a glass article of the present invention, an alkali-free glass article having a good glass composition uniformity can be obtained by using the granulated body of the present invention.

It is a flow which shows an example of the manufacturing process of a glass article. 4 is a powder X-ray diffraction spectrum of aluminate obtained in Preparation Example 1. 3 is a powder X-ray diffraction spectrum of aluminate obtained in Preparation Example 2. 2 is a powder X-ray diffraction spectrum of the granulated body obtained in Example 1. FIG.

As used herein, components of the glass is expressed as _{SiO 2, Al 2 O 3,} SrO and oxides BaO, etc., the content of each component to the whole glass (glass composition) is represented by mass percentage based on oxides.
In the present specification, the “glass raw material composition” is a composition comprising a plurality of components (sometimes referred to as “glass raw materials”) which are raw materials for glass. Examples of the glass raw material include oxides, composite oxides, and compounds that can be converted into oxides by thermal decomposition. Examples of the compound include hydroxide, carbonate, nitrate, halide and the like.
In the present specification, the “granulated body” is obtained by granulating a glass raw material composition, and basically includes all components necessary for the production of glass in one granulated body. For example, when a granulated body is heated and melted to vitrify one granulated body, a glass having a glass composition to be obtained can be obtained.
In this specification, “100% by mass of alkali-free glass obtained from a granulated product” used for the total amount of the composition amount means that no component other than the granulated product of the present invention is used as a component that can be a raw material of glass. The total mass of the solidified glass melt obtained by melting the granulated body (non-alkali glass). In addition, in a series of processes for producing a glass article by melting, molding, gradual cooling (solidification), and post-processing of a granulated product, no component other than the granulated product of the present invention is used as a component that can be a raw material for glass. In the product of each step, the glass composition (composition of components that can be a raw material of glass) is equal to each other. However, the component processed into the surface of a glass article by the surface treatment in a post-processing process etc. shall not be contained in the composition (glass composition) of a glass article.
In this specification, “average particle diameter” is a 50% diameter (D50) in the integrated fraction unless otherwise specified. When D50 is 1 mm or less, the 50% diameter in the volume-based integrated fraction measured using the laser diffraction method is defined as D50. When D50 is greater than 1 mm, the 50% diameter of the cumulative weight measured by a method of sieving and obtaining an average particle size (sieving method) is defined as D50. As a particle diameter measuring method by the laser diffraction method, the method described in JIS Z8825-2 (2001) is used.
In the present specification, “to” indicating a numerical range is used in the sense of including the numerical values described before and after the numerical value as lower and upper limits unless otherwise specified.

Hereafter, the manufacturing method of the granulated body of this invention and the manufacturing method of a glass article are demonstrated in detail.
≪Granule manufacturing method≫
The manufacturing method of the granulated body of this invention is a manufacturing method of the granulated body by mixing a glass raw material composition and water.
5-30 mass% is preferable with respect to 100 mass% of glass raw material compositions, as for the quantity of the water to mix, 10-26 mass% is more preferable, and 15-25 mass% is further more preferable. If the amount of water relative to the glass raw material composition is insufficient, it is difficult to obtain a strong granulated body. When the amount of water relative to the glass raw material composition is excessive, the granulated body tends to adhere to the surface of a device such as a mixer during granulation.

<Glass raw material composition>
In the present invention, the glass raw material composition essentially comprises an aluminum source and a silicon source.
[Aluminum source]
Glass material composition of the present invention, aluminate of formula xRO · Al ₂ O ₃ (hereinafter, referred to. Aluminate (1)) essential to the aluminum source comprising. X in the formula is 1 to 3. x is preferably 1 or 3, and more preferably 1. R in the formula is one or both of Sr and Ba. R being both Sr and Ba means a solid solution of aluminate (1) where R is Sr and aluminate (1) where R is Ba. Only 1 type may be used for an aluminate (1), and 2 or more types may be used for it.
The aluminate (1) in which R is Sr is selected from the group consisting of strontium aluminates represented by the following composition formulas (S1) and (S2) (hereinafter also referred to as (S1) and (S2), respectively). One or more selected are preferable.
SrO.Al ₂ O ₃ (S1),
3SrO.Al ₂ O ₃ (S2).
The aluminate (1) in which R is Ba is a barium aluminate represented by the following composition formulas (B1) and (B2) (hereinafter also referred to as (B1) and (B2), respectively). One or more selected are preferable.
BaO.Al ₂ O ₃ (B1),
3BaO · Al ₂ O ₃ (B2).
The aluminate (1) is more preferably at least one selected from the group consisting of (S1), (B1), and (S1) and (B1) solid solutions in that the curing rate does not become too fast. .
The aluminate (1) may contain manufacturing impurities in addition to Sr and Ba.

The aluminate (1) can be hydrated and gelled when it comes into contact with water, and then has a property of hardening (hydraulic).
When the aluminate (1) is (S1), (S2), or a mixture thereof, 3SrO.Al ₂ O ₃ · 6H ₂ O can be formed when the aluminate (1) comes into contact with water.
When the barium aluminate in the aluminate (1) is (B1), (B2), or a mixture thereof, when the aluminate (1) comes into contact with water, 3BaO · Al ₂ O ₃ · 6H ₂ O Can be generated.
In this invention, when a glass raw material composition contains aluminate (1), a strong granulated body is obtained. This is presumably because the curing rate when the aluminate (1) is cured by contact with water is not too fast or too slow relative to the mixing rate of the glass raw material.

As a method for obtaining the aluminate (1), the following method is preferable.
Strontium aluminate can be obtained by a method in which a strontium compound and an aluminum compound are mixed and heated. For example, strontium carbonate (SrCO ₃ ) and aluminum oxide (Al ₂ O ₃ ) are mixed so that the molar ratio of Al ₂ O ₃ is slightly higher than 1: 1, and heated to 1300 to 1600 ° C. for baking. By bonding, a mixture of SrO.Al ₂ O ₃ and Al ₂ O ₃ is obtained. By pulverizing the mixture by a known pulverization method, a mixed powder of strontium aluminate (SrO.Al ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ) is obtained.
Barium aluminate can be obtained by mixing and heating a barium compound and an aluminum compound. For example a BaO · _Al 2 _{O 3} by molar ratio of barium carbonate (BaCO ₃₎ and aluminum oxide _(Al 2 _{O 3)} is heated and mixed so that _Al 2 _{O 3} from 1-to-1 becomes slightly higher percentage A mixture of Al ₂ O ₃ is obtained. By pulverizing the mixture by a known pulverization method, a mixed powder of barium aluminate (BaO.Al ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ) is obtained.
Since the glass raw material composition may contain aluminum oxide as an aluminum source other than the aluminate (1), the strontium aluminate and barium aluminate obtained by the above method should be used as a mixed powder. Can do.

  The amount of the aluminate (1) is preferably 1 to 60% by mass and more preferably 2 to 20% by mass with respect to 100% by mass of the glass raw material composition. When the amount of aluminate (1) is not less than the lower limit within the range, a strong granulated product is easily obtained, and when it is not more than the upper limit, the granulated product may be formed on the surface of a device such as a mixer. Is difficult to adhere. The total amount of (S1) and (B1) is preferably 1% by mass or more and preferably 5% by mass or more with respect to 100% by mass of the glass raw material composition.

The glass raw material composition may contain other aluminates other than aluminate (1) as an aluminum source. Other aluminate, for example _{SrO · 6Al 2 O 3, SrO} · 2Al 2 O 3, BaO · 6Al 2 O 3, BaO · 2Al 2 O 3, CaO · Al 2 O 3, CaO · 2Al 2 O 3 Can be mentioned. Aluminates other than these aluminates (1) also have the property of being hydrated and gelled when contacted with water (cured).

When the glass raw material composition contains other aluminates other than the aluminate (1), the content is such that the granulated body becomes strong, and the other aluminates are 100% by mass with respect to the glass raw material composition. 20 mass% or less is preferable and 10 mass% or less is more preferable.
The glass raw material composition may contain aluminum oxide (alumina), aluminum hydroxide and the like in addition to the aluminate (1) as an aluminum source.

[Silicon source]
The silicon source is preferably powdered silica from the viewpoint of ease of handling. As a silicon source other than silica, anorthite (anocite) or the like may be used. Silica is preferably silica sand in terms of availability. As silica other than silica sand, quartz, cristobalite, amorphous silica, or the like may be used, and two or more of these may be used as appropriate.
It is preferable that a glass raw material composition contains 40-85 mass% of silica with respect to 100 mass% of glass raw material compositions, and it is more preferable to contain 40-60 mass%. If the content of silica is within these ranges, the shape of the granule is easily maintained.

[Calcium source, magnesium source, etc.]
The glass raw material composition may contain other components other than the silicon source and the aluminum source. Examples of other components include a calcium source and a magnesium source. Further, nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, ammonia and the like may be included.
The glass raw material composition preferably contains one or both of calcium oxide and calcium hydroxide as a calcium source. When the glass raw material composition contains calcium oxide or calcium hydroxide, a gel-like calcium hydrate can be formed when mixed with water. The gel-like calcium hydrate acts as a binder for the granule.
Moreover, when calcium oxide or calcium hydroxide is contained in the glass raw material composition, hardening of the aluminate (1) is promoted when mixed with water.
The calcium oxide or calcium hydroxide is preferably a powder.
1-20 mass% is preferable and, as for the total amount of calcium oxide and calcium hydroxide with respect to 100 mass% of glass raw material compositions, 3-10 mass% is more preferable. When the total amount of calcium oxide and calcium hydroxide is within the above range, a strong granulated body is easily obtained.

  In addition to the above glass raw materials, the glass raw material composition may contain a compound that can become CaO, SrO, or BaO during the glass production process. Specific examples include carbonates such as calcium carbonate, strontium carbonate, and barium carbonate. These may be used alone or in combination of two or more.

The glass raw material composition may contain dolomite. Dolomite is a mineral (ideal chemical composition: CaO · MgO · 2CO ₂ ) composed of calcium and magnesium carbonate, and is widely used as a glass raw material.

  The glass raw material composition preferably contains at least one selected from magnesium oxide and magnesium hydroxide as a magnesium source, and more preferably further contains at least one selected from magnesium chloride and magnesium sulfate. The total amount of the magnesium source in the glass raw material composition is preferably 0.1 to 18% by mass, more preferably 2 to 18% by mass in terms of MgO with respect to 100% by mass of the alkali-free glass obtained from the granulated body. When the glass raw material composition contains these magnesium-containing compounds, the granulated body tends to become hard.

A glass raw material composition can contain the component used as the clarifier of a glass, or a color tone regulator. As a fining agent and color tone adjusting agent, magnesium chloride, calcium chloride, strontium chloride and other chloride components; magnesium sulfate, calcium sulfate and other sulfate components; magnesium nitrate, calcium nitrate and other nitrate components; fluorite ( And CaF ₂ ), a petite (Fe ₂ O ₃ ), and the like. These may be used alone or in combination of two or more.
In particular, the use of one or both of a sulfate component and a nitrate component as a fining agent or a color tone adjusting component can be achieved by hardening the aluminate represented by aluminate (1) and other aluminates optionally used. This is preferable when the speed is increased. The amount of the sulfate component and the nitrate component is preferably 0.1 to 2.0% by mass and more preferably 0.5 to 1.0% by mass with respect to 100% by mass of the alkali-free glass obtained from the granulated body. .
Since the chloride component and the sulfate component are usually highly soluble in water and are dissolved or micronized by mixing with water, the D50 of the chloride component and sulfate component is not particularly limited.

[Composition of glass raw material composition]
The composition of the glass raw material composition is preferably adjusted so as to be substantially the same as the target glass composition in terms of oxide, except for components that are easily volatilized in the glass melting step.
The target glass in the present invention is preferably an alkali-free glass that does not substantially contain an alkali metal oxide such as Na ₂ O, Li ₂ O, or K ₂ O. “Substantially not contained” means that the amount of the alkali metal source in the glass raw material composition is 0.1% by mass or less in terms of oxide with respect to 100% by mass of the alkali-free glass obtained from the granulated body. It means that it is 0.02% by mass or less. The lower limit of the amount of the alkali metal source is 0% by mass, and 0% by mass means that it is below the detection limit.

The glass raw material composition is 40 to 85% by mass of SiO ₂ , 5 to 30% by mass of Al ₂ O ₃ , and 0 to 0 to MgO in terms of oxide with respect to 100% by mass of alkali-free glass obtained from the granulated body. The total amount of CaO, SrO and BaO is preferably 2 to 40% by mass, and the total amount of SrO and BaO is preferably more than 0% by mass. In addition to this, the target glass may contain a small amount of a non-metal oxide (such as sulfur oxide) and halogen. Since sulfur oxides and halogens are easily volatilized in the glass melting step, it is preferable to add more in the glass composition in consideration of melting conditions and the like.
In the present invention, since the glass raw material composition contains aluminate (1), the glass raw material composition contains one or both of SrO and BaO. The glass raw material composition contains 0 to 18% by mass of CaO in terms of oxide with respect to 100% by mass of the alkali-free glass obtained from the granulated body, the total amount of SrO and BaO is 2 to 35% by mass, and CaO and SrO. The total amount of BaO is preferably 2 to 40% by mass.
The glass raw material composition is 45 to 65% by mass of SiO ₂ , 10 to 25% by mass of Al ₂ O ₃ and 2 to 2% of MgO in terms of oxide with respect to 100% by mass of the alkali-free glass obtained from the granulated body. A glass raw material composition containing 18% by mass, 2-18% by mass of CaO, and a total amount of SrO and BaO of 2-15% by mass is more preferable.

The glass raw material composition preferably does not contain boric acid and boron oxide. The boric acid here is a general term for oxygen acids of boron such as orthoboric acid (H ₃ BO ₃ ) and metaboric acid. Boron oxide refers to a boron oxide typified by B ₂ O ₃ . When the glass raw material composition contains boric acid, boric acid and water are mixed to form a boric acid solution. When boron oxide is mixed with water, it at least partially dissolves to form a boric acid solution. When the raw material of the granulated body contains a boric acid solution, the curing rate of the aluminate (1) and other aluminates that are optionally used may be too slow.
The total amount of boric acid and boron oxide contained in the glass raw material composition is preferably 0 to 3% by mass, more preferably 0 to 1% by mass, and even more preferably 0% by mass. 0 mass% means that it is below the detection limit.

Since the glass raw material composition of this invention is used for manufacture of the granule used for manufacture of an alkali free glass, it does not contain an alkali metal source substantially. The amount of the alkali metal source in the glass raw material composition is 1% by mass or less, preferably 0.5% by mass or less, and preferably 0.1% by mass or less in terms of oxide with respect to 100% by mass of the glass raw material composition. Is more preferable.
When the glass raw material composition contains the alkali metal source in an amount larger than the above amount, when the glass raw material composition and water are mixed, alkali metal ions may be eluted to form an alkaline solution. When an alkaline solution is contained in the raw material of the granulated body, the curing rate of the aluminate (1) and other aluminates that are optionally used may be too high.
Moreover, when the glass raw material composition contains a large amount of an alkali metal source, it is difficult to use the granulated material for the production of alkali-free glass.

[Average particle size of glass raw material]
The glass raw material contained in the glass raw material composition is preferably in the form of a powder because it is easy to handle in a later step. The powder preferably has an appropriate particle size.
For example, when the glass raw material composition contains powdered silica, the D50 of silica is preferably 2 to 150 μm. The D50 of silica is more preferably 100 μm or less, further preferably 50 μm or less, and even more preferably 30 μm or less. The D50 of silica is more preferably 5 μm or more, further preferably 10 μm or more.
When the D50 of silica is not more than the upper limit of the above range, a strong granulated body can be easily obtained. Moreover, when a granulated body is heated to produce a glass melt, undissolved residue hardly occurs, and a homogeneous glass melt is easily obtained. When it is at least the lower limit of the above range, the glass raw material is less likely to agglomerate or scatter when the granulated body is produced.

As the aluminate (1), it is preferable to use a powdery aluminate (1). The D50 of the powdered aluminate (1) is preferably 1 to 100 μm, and more preferably 2 to 80 μm. When D50 of the powdered aluminate (1) is not less than the lower limit of the above range, it is difficult for the glass raw material to agglomerate or scatter when producing the granulated body, and if it is not more than the upper limit, the D50 can be produced in a relatively short time. A granulated body can be produced.
The powdered aluminate (1) may be a particle made of only the aluminate (1), or each particle may contain aluminum oxide, other aluminate, or the like.
When the glass raw material composition contains powdered calcium oxide, the D50 of the calcium oxide is preferably 1 to 100 μm, and more preferably 2 to 20 μm. When D50 of calcium oxide is not less than the lower limit of the above range, it is difficult for the glass raw material to agglomerate or scatter when the granulated product is produced, and if it is not more than the upper limit, a homogeneous glass melt can be easily obtained.
When the glass raw material composition contains powdered calcium hydroxide, the D50 of the calcium hydroxide is preferably 1 to 100 μm, and more preferably 2 to 20 μm. When the granulated product is produced when the D50 of the calcium hydroxide is not less than the lower limit of the above range, the glass raw material is less likely to aggregate and scatter, and when it is not more than the upper limit, a homogeneous glass melt can be easily obtained.

Aluminum oxide, magnesium oxide, magnesium hydroxide, dolomite, calcium carbonate, strontium carbonate, barium carbonate, fluorite, and petal are poorly water-soluble raw materials with relatively low solubility in water. It is difficult to miniaturize when mixed. When the glass raw material composition contains these hardly water-soluble raw materials in powder form, D50 of each poorly water-soluble raw material is preferably 100 μm or less, more preferably 40 μm or less, and further preferably 20 μm or less. Although the lower limit of D50 of a hardly water-soluble raw material is not specifically limited, 1 micrometer or more is preferable and 2 micrometers or more are more preferable.
When the D50 of the poorly water-soluble raw material is not more than the upper limit of the above range, a homogeneous glass melt can be easily obtained, and when it is not less than the lower limit of the above range, Difficult to occur.

It is preferable that the glass raw material is used after being finely divided as required. Or when mixing the glass raw material composition containing a poorly water-soluble raw material and water, it is preferable to make the glass raw material fine particles by using a ball mill or the like.
Since powders such as magnesium chloride and calcium chloride have high solubility in water, they are easily dissolved or micronized when mixed with water even if D50 before mixing is large. Therefore, D50 of these powders is not particularly limited.

It is preferable to adjust D50 of the powder with respect to each component in the case of using a glass raw material in powder form to an appropriate size according to D50 of the granulated body obtained by granulating the glass raw material composition. If the D50 of the glass raw material is too large relative to the D50 of the granulated body, the composition of the individual granulated bodies may be non-uniform.
For example, when D50 of the granulated body is 3 mm or less, D50 of the glass raw material is preferably 50 μm or less, more preferably 20 μm or less, and particularly preferably 10 μm or less.
Further, D50 of the glass raw material is preferably 1/200 to 1/10 of D50 of the granulated body, and more preferably 1/100 to 1/20.
Even when the ratio of D50 of the glass raw material to D50 of the granule satisfies the above range, it is possible to perform the step of making the glass raw material fine particles before preparing the glass raw material composition. It is preferable in terms of improving homogeneity.

<Step of granulating the glass raw material composition>
In the step of granulating the glass raw material composition, when the glass raw material composition and water are mixed, the surface of the glass raw material comes into contact with water. The glass raw material composition contains aluminate (1), and when the aluminate (1) comes into contact with water, a gel-like hydrate can be formed. This gel-like hydrate is considered to bind other glass raw materials.
As a method of mixing the glass raw material composition and water, the glass raw material composition is mixed and then further mixed by adding water, and the glass raw material composition and water are not mixed at one time but divided. There is a way to repeat mixing. In the latter method, it is preferable to dissolve a water-soluble glass raw material in water and mix it with water-insoluble or poorly water-soluble glass raw material. Moreover, it is preferable that the glass raw material containing aluminate (1) is mixed with water in the first stage. It is preferable to use a glass raw material that is insoluble or hardly soluble in water in advance, with stirring and mixing, because the composition variation in the granulated body is reduced.

Examples of the granulation method include a method in which a glass raw material composition and water are mixed and then compression-molded and granulated, and a method in which the glass raw material composition and water are mixed and granulated without compression. In the present invention, it is preferable to use an appropriate granulation method according to D50 of the intended granule.
For example, when it is desired that the D50 of the granulated body exceeds 15 mm, in the step of granulating the glass raw material composition, it is preferable that the glass raw material composition and water are mixed and then compression molded to form a granulated body. Below, the granulated body obtained by this method is called briquette.
It is preferable to mix the glass raw material composition so that the glass raw material composition is sufficiently homogeneous. As a method for compression molding the glass raw material composition and water after mixing, known methods can be used as appropriate.
As a device for compression-molding the glass raw material composition and water, for example, a tableting machine, an extrusion molding machine, a briquette machine, or the like can be used as appropriate.

When it is desired to obtain a granulated body having a D50 of 15 mm or less, it is preferable to obtain a granulated body by solidifying without compression while mixing the glass raw material composition and water.
A known method can be applied to the method of mixing the glass raw material composition and water, and is not particularly limited. As a device for mixing the glass raw material composition and water, a ball mill, a Henschel mixer, an extrusion granulator, a stirring granulator, a rolling granulator, or the like can be used. A method using a rolling granulator (rolling granulation method) is preferable in that the glass raw material composition and water are easily and uniformly mixed.
As a method of adding water to the glass raw material composition, a method of spraying water on the glass raw material composition can be used. The spraying of water onto the glass raw material composition may be performed on the glass raw material composition being stirred or may be performed on the glass raw material composition being stationary. Since granulation starts from the part where water and the glass raw material composition are in contact with each other, in order to prevent the glass raw material composition from being locally cured, the total amount of water added in the granulation step is short, for example, 1 second to 30 minutes. Preferably, it is added in 1 second to 10 minutes.

As the rolling granulation method, for example, a predetermined amount of a glass raw material composition and a predetermined amount of water are placed in a container of a rolling granulator and granulated by rotating the container, The glass raw material composition is placed in a container of a tumbling granulator, and the glass raw material composition is mixed and tumbled and stirred while rotating the container, while granulating the glass raw material composition by spraying a predetermined amount of water. The method of doing is mentioned. As the container of the rolling granulator, a dish-shaped, cylindrical, conical rotating container, a vibrating container, or the like can be used.
In addition, the rolling granulator used in the rolling granulation method is, for example, a container that rotates with a direction inclined with respect to the vertical direction as a rotation axis, and a rotation in the opposite direction to the container around the rotation axis in the container. And the like provided with rotating blades. Examples of such a rolling granulator include an Eirich intensive mixer (manufactured by Eirich), a Laedige mixer (manufactured by Laedige), and the like.

In the granulation step, the mixing conditions such as the time for mixing the glass raw material composition with water can be appropriately determined according to the type and amount of the glass raw material, the amount of water, the apparatus to be used, and the like.
When the raw material composition and water are granulated and formed into a granulated product, heat is generated when the aluminate (1) comes into contact with water to form a hydrate. The temperature of the glass raw material composition in the granulation step is preferably 50 ° C. or higher because the step can be shortened. If the temperature of the glass raw material composition is too high, curing of the glass raw material composition may be locally promoted and a desired granulated body may not be formed or the expected granulated body size may not be achieved.
Moreover, after performing the prehydration process which mixes and hydrates the powder containing aluminate (1) with water beforehand, when it mixes with the glass raw material composition except the powder containing aluminate (1), it will be uniform. It is preferable in terms of easy mixing. The amount of water used in the prehydration step may be a part or all of the water used in the granulation step. The amount of water is preferably 50 to 200% by mass, more preferably 50 to 100% by mass, with respect to 100% by mass of the total amount of the powder containing aluminate (1) and other aluminate powders optionally used. .

  Since the granulated product obtained in the granulating step contains water, it may be dried. The temperature for drying the granulated body is, for example, 800 ° C. or less, and preferably 500 ° C. or less. The drying temperature is more preferably 80 to 200 ° C. in terms of work efficiency. The obtained granulated body may be sieved as necessary.

<Granulated body>
The granulated body of the present invention is a granulated body used for the production of a glass article, and requires a silicon source and an aluminum source. The composition of the granulated body is adjusted so that a glass article having a desired glass composition is obtained when it is melted by heating and vitrified. The amount of the alkali metal component in the granulated body is 1% by mass or less, preferably 0.1% by mass or less, in terms of oxide, based on 100% by mass of the alkali-free glass obtained from the granulated body. 02 mass% or less is more preferable.
The aluminum source in the granulated body of the present invention includes 3SrO · Al ₂ O ₃ · 6H ₂ O, 3BaO · Al ₂ O ₃ · 6H ₂ O, and 3SrO · Al ₂ O ₃ · 6H ₂ O and 3BaO · Al _At least one selected from a solid solution of ₂ O ₃ · 6H ₂ O is included. These are components produced by contact between the aluminate (1) and water. Since this component acts as a binder, a strong granulated body can be obtained.
These components can be confirmed by analyzing an X-ray diffraction spectrum obtained by a powder X-ray diffraction method. Specifically, in the case of using CuKα rays, the diffraction line of 211 surface of 3SrO · Al ₂ O ₃ · 6H ₂ O has 2θ of 16.619 degrees, the diffraction line of 420 surface has 2θ of 30.634 degrees and 642 surfaces. The diffraction line appears at 2θ of 52.462 degrees.
3SrO · Al ₂ O ₃ · 6H ₂ O, 3BaO · Al ₂ O ₃ · 6H ₂ O, and 3SrO · Al ₂ O ₃ · 6H ₂ O and 3BaO · Al ₂ O ₃ · 6H ₂ O in the granulated body 1-60 mass% is preferable with respect to 100 mass% of granulated bodies, and, as for the total amount of at least 1 sort (s) chosen from solid solution, 2-20 mass% is more preferable. When this total amount is not less than the lower limit of the above range, a strong granulated body can be easily obtained.
The composition of the granulated body is usually almost equal to the composition of the glass melt obtained by melting the granulated body except for the fining agent. When boron oxide is contained in the glass melt obtained by melting the granulated body, it is preferable to add more in consideration of volatilization of boric acid. Even when boron oxide is not contained in the glass obtained by melting the granulated body, boric acid may be present in the granulated body if the boric acid in the granulated body volatilizes.

It is preferable that D50 of the granulated body of this invention is 50 micrometers-50 mm. When the D50 of the granulated body is in the above range, dust is hardly generated and a highly uniform granulated body is easily obtained.
When the granulated body is a briquette, the shape of the briquette is, for example, a sphere, a cylinder, a rectangular parallelepiped, an ellipsoid, or the like. When the briquette is a sphere, D50 is preferably 1 to 50 mm, and more preferably 5 to 30 mm. When a briquette is an ellipsoid etc., it is preferable that the average value of a major axis is 5-50 mm, and it is more preferable that it is 10-30 mm. When it is at least the lower limit of the above range, it can be easily molded with a general briquette machine, and when it is at most the upper limit, homogeneous glass is easily obtained.
When the glass raw material composition and water are solidified while mixing to form a granulated body, the shape of the granulated body is, for example, a sphere. When the granulated body is a sphere, D50 is preferably 50 μm to 15 mm, and more preferably 1 to 10 mm. If it is at least the lower limit of the above range, the granulated body itself is less likely to become dust, and if it is not more than the upper limit, a highly homogenized granule is likely to be obtained.

In particular, the D50 of the granulated material used in the method for producing a glass melt by the air melting method described later is preferably 50 to 1000 μm, more preferably 50 to 800 μm. It is preferable that D50 of the granulated body is 50 μm or more because scattering of raw materials can be reduced. Moreover, it is preferable at the point which is easy to vitrify rapidly that D50 of a granule is 1000 micrometers or less. D50 of a granulated body can be adjusted according to conditions, such as a composition of a glass raw material composition, the mixing method in a granulation process, and mixing time. When a glass melt is produced by an air melting method, it is more preferable that the granule has a small variation in particle size so that a glass article having a uniform glass composition can be obtained.
1-50 mm is preferable and, as for D50 of the granule used for the method of manufacturing a glass melt by the normal melting method mentioned later, 1-15 mm is more preferable. When D50 of the granulated body is in the above range, entrained bubbles at the time of melting tend to be reduced.
When manufacturing a glass article using the glass melt manufactured by the normal melting method, it is preferable that a granulated body does not contain organic substance. This is because when the granulated body contains an organic substance, the color tone and appearance of the glass article may be impaired.

≪Glass article manufacturing method≫
One embodiment of the method for producing a glass article of the present invention is a method in which the granulated body of the present invention is heated to obtain a glass melt, the glass melt is shaped and slowly cooled to obtain a glass article. . In another embodiment of the method for producing a glass article of the present invention, the granulated body is heated by the method for producing a granulated body of the present invention to obtain a glass melt, and the glass melt is molded and slowly cooled. This is a method for obtaining a glass article.
<Melting process>
A known method for melting the glass raw material can be applied to the method for melting the granule, and is not particularly limited. The granulated material may be melted by a normal melting method using a Siemens type or crucible type glass melting furnace, or by an air melting method.
When a large amount of glass is produced using a large apparatus, a cullet obtained by crushing a granulated body and a glass plate may be mixed and added. The granulated body of the present invention is preferable because it is difficult to break even when the granulated body and cullet are mixed and charged. The cullet preferably has a glass composition equal to the glass melt obtained from the granulated body of the present invention. Specifically, it is preferable to use the cullet of the glass article obtained by using the granulated body of the present invention or the cullet produced in the process of producing the glass article.

[Normal melting method]
When the granulated material is melted by the ordinary melting method, the granulated material is put into a glass melting furnace, heated to proceed with melting, and gradually made into a glass melt. When a glass melt is present in the glass melting furnace, the granulated material is put on the surface of the glass melt, and the granulated material becomes a lump (also called a batch pile or a batch pile) as a burner. Etc. and melt by heating.

[Air melting method]
The air melting method is a method in which a glass raw material is melted in a gas phase atmosphere to form molten glass particles, and the molten glass particles are accumulated to form a glass melt. The in-flight melting method is also referred to as an in-flight-melting method. When the granulated body is melted by the air melting method, first, the granulated body is introduced into a high-temperature gas phase atmosphere of an air heating device and melted in the gas phase atmosphere to obtain molten glass particles. A well-known thing can be used for an air heating apparatus. Since the granulated material of the present invention is not easily broken, the generation of fine powder can be suppressed even when the particles collide with each other or between the particles and the inner wall of the conveyance path during conveyance.
Next, the molten glass particles in the air heating apparatus are accumulated to obtain a glass melt, and the taken-out glass melt is subjected to the next molding step. As a method for accumulating the molten glass particles, for example, there is a method in which the molten glass particles falling by their own weight in the gas phase atmosphere are received and accumulated in a heat-resistant container provided in the lower part of the gas phase atmosphere.

<Molding process and annealing process>
FIG. 1 is a flowchart showing an example of a method for producing a glass article of the present invention. Reference sign S1 is a glass melting step.
First, the glass melt obtained in the glass melting step S1 is molded into a target shape in the molding step S2, and then slowly cooled in the slow cooling step S3. Thereafter, the glass article G5 is obtained by performing post-processing by a known method such as cutting or polishing in the post-processing step S4 as necessary. Here, the post-processing step may be a surface treatment step or the like in addition to the post-step that does not affect the glass composition of the glass article.
When the glass article is a plate-like article, the forming step can be performed by a known method such as a float method, a downdraw method, or a fusion method. The float process is a method for forming a glass melt into a plate shape on molten tin. The slow cooling step S3 can also be performed by a known method. In the production of a glass article, a glass article of good quality can be obtained while preventing the glass raw material from being scattered by using the granulated body of the present invention.

<Glass articles>
The glass article in the present invention refers to a glass article that has been formed into a desired shape by melting the granulated body in the melting step, forming it, gradually cooling it, and then cutting it as necessary. Examples of the shape of the glass article include a flat plate shape, a curved surface shape, a cylindrical shape, and a container shape. In addition, the glass article may be subjected to a surface treatment in a step after the melting step or after making into a glass article.
The glass article produced by the method of the present invention is preferably a glass article made of alkali-free glass. The glass article preferably contains the following glass components. However, 100% by mass of the glass article in the case of showing the glass component of the glass article as described below represents the total mass of the solidified glass melt obtained by melting the granulated body, and the surface in the post-processing step The mass of the component processed on the surface of the glass article by treatment or the like is not included.
Glass component: (oxide conversion display with respect to 100% by mass of glass article):
SiO _2; 40 to 85 wt%,
Al ₂ O ₃ ; 5 to 30% by mass,
MgO; 0 to 18% by mass,
Total amount of CaO, SrO and BaO; 2 to 40% by mass (however, the total amount of SrO and BaO exceeds 0% by mass).
In addition, the glass article may contain a small amount of a non-metal oxide (such as sulfur oxide) or halogen. The total amount of non-metal oxide and halogen is preferably 0 to 5% by mass.
The glass article contains 0 to 18% by mass of CaO in terms of oxide with respect to 100% by mass of the glass article, the total amount of SrO and BaO is 2 to 35% by mass, and the total amount of CaO, SrO and BaO is 2 to 2%. It is preferable that it is 40 mass%.
Further, the glass article is 45 to 65 mass% of SiO ₂ , 10 to 25 mass% of Al ₂ O ₃ , 2 to 18 mass% of MgO, and 2 of CaO in terms of oxide with respect to 100 mass% of the glass article. It is more preferable that the total amount of SrO and BaO is 2 to 15% by mass.

The glass article of the present invention is preferably a plate-like glass article. A plate-shaped glass article is used for a display substrate or the like. When the glass article is a plate-like glass article, the glass article preferably contains 0.4% by mass or more of MgO. The glass composition is suitable for forming into a plate shape using a float process.
Glass _article, either do not contain B 2 _{O 3,} or preferably contains less _B 2 _{O 3.} The content of B ₂ O _{3 in} the glass article is preferably 0 to 3 mass%, more preferably 0 to 1 mass%, and still more preferably zero mass% in terms of oxide with respect to 100 mass% of the glass article. This is because if the amount of B ₂ O ₃ is small, the strain point of the glass increases.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
[Preparation Example 1: Preparation of aluminate]
The mixture was weighed so that the molar ratio of strontium carbonate (SrCO ₃ ) to aluminum oxide (Al ₂ O ₃ ) was 1: 1.5 and mixed for 10 minutes. After that, they were packed in a cylindrical platinum container having a diameter of about 150 mm and a height of about 50 mm, and placed in an electric furnace maintained at 1350 ° C. and fired. After cooling, a powder containing strontium aluminate (hereinafter referred to as “SA powder”) was obtained by grinding so that D50 was about 50 μm.
FIG. 2 shows an X-ray diffraction spectrum obtained by a powder X-ray diffraction method using CuKα rays for the obtained SA powder. In FIG. 2, the peak marked with a black circle (●) is the diffraction peak of SrO · Al ₂ O ₃ , the peak marked with a white circle (◯) is the diffraction peak of SrO · 6Al ₂ O ₃ , and the triangle (Δ) The attached peak is a diffraction peak of Al ₂ O ₃ . As can be seen from this result, the amount of SrO.6Al ₂ O ₃ is small. Therefore, the mass ratio of the contents of strontium aluminate (SrO.Al ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ) is approximately 80 to 20, and 100% by mass of the SA powder in this example is approximately strontium aluminate. _{(SrO · Al 2 O 3)} 80 wt% and aluminum oxide _{(Al 2} O 3) consisting of 20 wt%.

[Preparation Example 2: Preparation of aluminate]
Weigh so that the molar ratio of barium carbonate (BaCO ₃ ) and aluminum oxide (Al ₂ O ₃ ) is 1 to 1.5, and calcine and grind in the same manner as in Preparation Example 1 to contain barium aluminate A powder (hereinafter referred to as “BA powder”) was obtained.
FIG. 3 shows an X-ray diffraction spectrum obtained by a powder X-ray diffraction method using CuKα rays for the obtained BA powder. In FIG. 3, the peak with a black circle (●) is the diffraction peak of BaO · Al ₂ O ₃ , and the peak with a triangle (Δ) is the diffraction peak of Al ₂ O ₃ . From this result, it can be confirmed that the obtained BA powder is a mixed powder of barium aluminate (BaO.Al ₂ O ₃ ) and aluminum oxide (Al ₂ O ₃ ). Barium aluminate (BaO · _Al 2 _{O 3)} and aluminum oxide _(Al 2 _{O 3)} barium aluminate which is calculated on the assumption that free of other components (BaO · _Al 2 _{O 3)} and aluminum oxide ( The mass ratio of the content with Al ₂ O ₃ ) was approximately 83:17. The BA powder 100 wt% of the present embodiment since the barium aluminate _{(BaO · Al 2 O 3)} 83 wt% and aluminum oxide _{(Al 2} O 3) is 17 wt%.

[Examples 1 to 9: Production example of granulated body]
Granules were produced using the SA powder and BA powder obtained in Preparation Examples 1 and 2. Examples 8 and 9 are comparative examples in which neither SA powder nor BA powder is used.
According to the composition of the glass raw material column shown in Tables 1 and 2, 3 kg of powdery glass raw material was weighed. Magnesium sulfate is heptahydrate and magnesium chloride is hexahydrate. Alumina cement is alumina cement No. 1 (AC-1) manufactured by AGC Ceramics Co., which is a cement containing calcium aluminate (CaO.Al ₂ O ₃ ) as a main component, and has a chemical composition expressed by mass percentage. SiO ₂ is 4.0%, Al ₂ O ₃ is 55.0%, Fe ₂ O ₃ is 1.0%, TiO ₂ is 2.7%, CaO is 36.0%, MgO is 0.6%. is there.
The composition of the glass raw materials in Examples 1, 2, and 9 is a composition in which a glass having the glass composition G1 shown in Table 3 is obtained. The resulting formulation. The glass composition G1 and the glass composition G2 in Table 3 do not contain alkali metal and boric acid.
The content of aluminate (1) shown in Tables 1 and 2 is the glass raw material obtained by calculation from the content of aluminate (1) in SA powder or BA powder and the blending amount of SA powder or BA powder. The total amount (unit: mass%) of the aluminate (1).
Table 4 shows D50 of each raw material measured by the laser diffraction method. D50 was not measured for magnesium sulfate and magnesium chloride not shown in Table 4. This is because these raw materials are easily dissolved in water.

Using a rolling granulator (manufactured by Eirich Co., Ltd .: Eirich Intensive Mixer R02), granulation was performed according to the following procedure.
Of 3.0 kg of glass raw material, magnesium sulfate and magnesium chloride were dissolved in 570 g of water, and the rest was put into a rolling granulator. Mixing was performed under conditions of a pan rotation speed of 42 rpm, a rotor rotation speed of 900 rpm, and a mixing time of 30 seconds.
Subsequently, while stopping the rotor and rotating only the pan, 570 g of water in which magnesium sulfate and magnesium chloride were dissolved was added, and the rotor rotation speed was increased to 3000 rpm, and granulation was performed for 18 minutes. During this time, 20 g of water was added in total while watching the situation.
Next, after the rotor rotation speed was lowered to 900 rpm and sizing for 1 minute, the mixture was put in a stainless steel container and dried in a hot air dryer at 80 ° C. for 12 minutes to obtain a granulated body.

About the obtained granulated body, the 50% diameter (D50) of the total weight by the method (screening method) which classifies with a sieve and calculates | requires an average particle diameter was measured. The results are shown in Tables 1 and 2. Since Example 9 could not be granulated, the average particle size was not determined.
FIG. 4 shows an X-ray diffraction spectrum obtained by a powder X-ray diffraction method using CuKα rays for the granulated body obtained in Example 1. In this X-ray diffraction spectrum, the peak marked with a black circle (●) is a diffraction peak of 3SrO · Al ₂ O ₃ · 6H ₂ O, and the peak marked with a triangle (Δ) is 3CaO · Al ₂ O ₃ · 6H ₂ O. The peaks marked with x are SiO ₂ diffraction peaks, and the peaks marked with diamonds (菱) are Al ₂ O ₃ diffraction peaks. That is, the diffraction peak of 3SrO · Al ₂ O ₃ · 6H ₂ O can be confirmed at 16.619 degrees, 30.634 degrees, and the like.

[Example 10: Production example of granulated body]
In this example, after performing a preliminary hydration process in which the powder containing aluminate (1) is mixed with water and hydrated in advance, the powder is mixed with the glass raw material composition excluding the powder containing aluminate (1). Granules were produced using the method.
First, 3 kg of glass raw material was weighed with the formulation shown in Table 2 in terms of mass percentage. Of these, 330 g of BA powder was dispersed in 200 g of water and allowed to hydrate for 6 hours at room temperature to form a slurry. Magnesium sulfate and magnesium chloride were dissolved in 370 g of water to obtain an aqueous solution.
Using the same rolling granulator as in Example 1, granulation was performed according to the following procedure.
Of the 3.0 kg of glass raw material, the remainder except for BA powder, magnesium sulfate and magnesium chloride was put into a rolling granulator. Mixing was performed under conditions of a pan rotation speed of 42 rpm, a rotor rotation speed of 900 rpm, and a mixing time of 30 seconds.
Subsequently, the rotor was stopped and the BA powder slurry prepared in advance and an aqueous solution in which magnesium sulfate and magnesium chloride were dissolved were added while rotating only the pan, and the rotor speed was increased to 3000 rpm for 10 minutes. Done the grain. During this time, 20 g of water was added in total while watching the situation.
Next, after the rotor rotation speed was lowered to 900 rpm and sizing for 1 minute, the mixture was put in a stainless steel container and dried in a hot air dryer at 80 ° C. for 12 minutes to obtain a granulated body.

[Hardness of granulated body]
About the obtained granulated body, hardness was evaluated in the following procedures.
After placing 50 g of alkali-free glass cullet and 50 g of granulated material in a 250 ml plastic container with a thickness of about 1 mm and a size of about 20 mm in length and 20 mm in width into a 250 ml plastic container, a sieve with an opening of about 200 μm is placed. The weight of the particles passed through was measured, and the ratio of the weight of the particles to the original weight was defined as the pulverization rate (unit:%). The smaller this value is, the stronger the granule is, and it is hard to be pulverized and scattered.
The hardness of the granulated body was evaluated based on the pulverization rate. The case where the value of the pulverization rate is less than 2% is “A”, the case where it is 2% or more and less than 4% is “B”, the case where it is 4% or more and less than 20% is “C”, the case where 20% or more is “ D ". The hardness of the granulated body is preferably A, B or C.
The results are shown in Tables 1 and 2.

As shown in the results of Tables 1 and 2, in Examples 1 to 7 using SA powder or BA powder containing aluminate (1) as a part of the glass raw material, a strong granulated body was obtained. Since the granulated body of Examples 1-7 does not contain an alkali metal and boron, it is suitable for the production of an alkali-free glass not containing boric acid (B ₂ O ₃ ).
Comparing Example 1 and Example 2, Example 1 using calcium hydroxide has a lower pulverization rate of the granulated body. When Example 3, Example 4 and Example 5 are compared, Example 5 with a small content of aluminate (1) is slightly pulverized in the granulated product.
On the other hand, the granulated body obtained in Example 8 in which the aluminate (1) was not contained in the glass raw material composition was easily pulverized. For this reason, the granulated body obtained in Example 8 is likely to be finely pulverized in the glass production process, and the uniformity of the glass composition is likely to be lowered.
Since Example 9 did not contain aluminate (1), it could not be granulated as described above.
In Example 10, since the preliminary hydration step in which the aluminate (1) was previously mixed with water and hydrated was performed, the mixing time could be shortened.

[Manufacture of glass articles]
The granulated bodies of Examples 1 to 7 were put in a platinum crucible, heated and melted in an electric furnace at 1550 ° C. for 60 minutes, and the whole platinum crucible was gradually cooled. Thereafter, the glass in the platinum crucible was cut out with a core drill and polished to obtain a glass article. As a result of analyzing the glass composition of the glass article, a target glass composition almost as shown in Table 3 was obtained except for Cl and SO ₃ as fining agents.

S1 Glass melting step S2 Molding step S3 Slow cooling step S4 Post-processing step G5 Glass article

Claims (15)

A method for producing a granulated body by mixing a glass raw material composition and water, wherein the glass raw material composition is an aluminate represented by the formula xRO · Al ₂ O ₃ (where x is 1 to 3, R is one or both of Sr and Ba.) A method for producing a granulated body used for producing an alkali-free glass containing an aluminum source and a silicon source.   The method for producing a granulated body according to claim 1, wherein the glass raw material composition contains one or both of calcium oxide and calcium hydroxide.   The manufacturing method of the granulated body of Claim 1 or 2 in which the said glass raw material composition contains one or both of a sulfate and nitrate.   The said silicon source is a silica and the average particle diameter of this silica is 2-150 micrometers, The manufacturing method of the granulated body as described in any one of Claims 1-3. Method for producing a granulated product according to any one of claims 1 to 4 x is 1 in the formula xRO · _Al 2 _{O 3.} The glass raw material composition is, in terms of oxide relative to the non-alkali glass 100 wt% obtained from the granulator body, the SiO ₂ 40 to 85 wt%, the _Al 2 _{O 3} 5 to 30 wt%, the MgO 0 The granulated body according to any one of claims 1 to 5, comprising ~ 18% by mass, the total amount of CaO, SrO and BaO being 2 to 40% by mass, and the total amount of SrO and BaO being more than 0% by mass. Manufacturing method.   The method for producing a granulated body according to any one of claims 1 to 6, wherein the granulated body is obtained by solidifying the glass raw material composition and water.   The method for producing a granulated body according to any one of claims 1 to 6, wherein the glass raw material composition and water are mixed and then compressed to obtain a granulated body.   The glass raw material composition does not substantially contain boric acid and boron oxide, or the total amount of boric acid and boron oxide is more than 0% by mass and 3% by mass or less with respect to 100% by mass of the glass raw material composition. The manufacturing method of the granulated material as described in any one of Claims 1-8. A granulated material used for manufacturing a glass article made of alkali-free glass,
The granulated body essentially comprises a silicon source and an aluminum source,
The aluminum _{source, 3SrO · Al 2 O 3 ·} 6H 2 O, of _{3BaO · Al 2 O 3 · 6H} 2 O and _{3SrO · Al 2 O 3 · 6H} 2 O and _{3BaO · Al 2 O 3 · 6H} 2 O solid solution Granules which are at least one selected from   The granulated body according to claim 10, wherein the granulated body has an average particle diameter of 50 µm to 50 mm. 0 The granule is in terms of oxide relative to the non-alkali glass 100 wt% obtained from the granulator body, the SiO ₂ 40 to 85 wt%, the _Al 2 _{O 3} 5 to 30 wt%, of MgO The granulated body according to claim 10 or 11, which is a granulated body containing 18% by mass, wherein the total amount of CaO, SrO and BaO is 2 to 40% by mass, and the total amount of SrO and BaO is more than 0% by mass.   A granulated body is obtained by the method for producing a granulated body according to any one of claims 1 to 9, and the granulated body is heated to obtain a glass melt, and the glass melt is molded and gradually added. A method for producing a glass article that is cooled to obtain a glass article.   The manufacturing method of the glass article which heats the granule as described in any one of Claims 10-12, obtains a glass melt, shape | molds this glass melt, and anneals, and obtains a glass article. Glass articles made of alkali-free glass contain 40 to 85 mass% of SiO ₂ , 5 to 30 mass% of Al ₂ O ₃ , and 0 to 18 mass% of MgO in terms of oxide with respect to 100 mass% of the glass article. The method for producing a glass article according to claim 13 or 14, wherein the total amount of CaO, SrO, and BaO is 2 to 40% by mass, and the total amount of SrO and BaO is more than 0% by mass.

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