TW200906755A - Method for producing alkali-free glass - Google Patents

Abstract

Disclosed is a method for producing a highly uniform and highly flat alkali-free glass which has only a few bubbles therein. Specifically disclosed is a method for producing an alkali-free glass, wherein a glass raw material containing a silicon source, an alkaline earth metal source and a boron source is melted and molded. This method for producing an alkali-free glass is characterized in that a material containing 15-100% by mole (in terms of MO, and hereinafter M represents an alkaline earth metal element) of a hydroxide of an alkaline earth metal relative to 100% by mole (in terms of MO) of the alkaline earth metal source is used as the alkaline earth metal source.

Description

200906755 IX. Description of the Invention [Technical Field of the Invention] The present invention relates to a method for producing an alkali-free glass. [Prior Art] A glass substrate for a display such as a liquid crystal display device is required to have substantially no alkali metal. Therefore, the glass substrate is made of an alkali-free glass. The glass substrate is required to have high chemical resistance, high durability, less bubbles in the glass, high homogeneity, and high flatness. However, the glass raw material of the alkali-free glass does not substantially contain the metal-detecting compound, so the glass raw material is not easily melted. Therefore, the sand of the main component of the glass raw material must use the smaller particle size. When the solubility, chemical resistance, and durability are to be imparted to the alkali-free glass, the composition may contain B203. The raw material of B2〇3 can be used from the viewpoint of being inexpensive and easy to obtain, and orthoboric acid (sometimes called only boric acid) can be used. However, when a glass raw material containing orthoboric acid is used, the following problems may occur. (1) In the presence of orthoboric acid, the cerium sand having a small particle size tends to aggregate, and the amount of the glass raw material to be fed into the melting kiln is likely to be unstable. Therefore, the temperature of the molten glass in the melting kiln is unstable, or the cycle and residence time of the molten glass are unstable. As a result, the melting of the glass raw material was uneven, or the composition of the molten glass was uneven. (2) When the glass raw material contains an alkaline earth metal compound, the raw material of the glass raw material in the dissolution kiln is melted and the ortho-boric acid and the alkaline earth metal compound are aggregated, and the mixture is prone to agglomerate -5-200906755. The orthoboric acid and the alkaline earth metal compound promote the melting of the cerium sand. Therefore, when agglomerates are generated, the glass raw materials in the melting kiln are not uniformly melted, or the composition of the molten glass is uneven. When the problem of (1) or (2) occurs, the homogeneity of the molten glass is deteriorated, so that the homogeneity and flatness of the formed alkali-free glass are lowered. Further, due to the cycle • the residence time is unstable, a part of the molten glass flows out of the melting kiln before the bubbles are removed from the molten glass in the melting kiln by the clearing agent. Since the melting of the glass raw material is not uniform, the effect of the clearing agent for the slow-melting molten sand is insufficient, and the bubbles in the molten glass cannot be sufficiently removed. In order to improve the homogeneity of the alkali-free glass, it is proposed to control the glass raw material of the particle size of the alkaline earth metal compound (cerium carbonate and dolomite) (Special Document 1). However, the glass raw material of the special document 1 does not consider the slower molten sand at all. When the melting of the strontium sand is slow, the unmelted strontium sand is trapped by the bubbles generated in the glass melt and gathers near the surface layer of the glass melt, so the surface layer of the glass melt and the Si〇2 component of the outer portion thereof The composition ratio is different, and the homogeneity of the glass may be lowered. [Problem to be Solved by the Invention] [Technical Problem] The present invention provides a method for producing an alkali-free glass which has few bubbles in glass and is excellent in homogeneity and flatness. . [Means for Solving the Problem] -6-200906755 In order to achieve the above object, the present invention adopts the following configuration. The method for producing an alkali-free glass according to the present invention is a method for producing an alkali-free glass obtained by melting and molding a glass raw material containing a source of cerium, an alkaline earth metal, and a boron source, characterized in that the alkaline earth metal source is used relative to an alkaline earth metal. Source 1 0 0 摩尔% ( Μ 0 conversion, but Μ alkaline earth metal elements, the same below), containing alkaline earth metal hydroxide 15 to 100 mol % (ΜΟ conversion). The alkaline earth metal as the source of the alkaline earth metal is preferably one or two or more elements selected from the group consisting of Mg, Ca, Sr and Ba. The boron source is preferably used in an amount of 1% by mass (in terms of b2o3) of the boron source, and 1 to 30% by mass of anhydrous boric acid (in terms of B 2 Ο 3 ). The glass raw material is preferably a glass raw material having an alkali-free glass having the following composition (1), and particularly preferably having the following composition (2) or (3) to be alkali-free. Glass raw material for glass.

Si〇2: 50 to 66% by mass, ΑΙ2〇3: 1〇·5~22% by mass 'B2〇3: 5 to 12% by mass' Mg〇: 〇~8 mass%, CaO: 〇~14.5 mass °/ 〇' 81'0: 0~24 quality. /. , ^0: 0~13.5 mass%' \^0 + €&0 + 81*0 + 3&0:9~29.5 mass °/. ...(1)

Si02: 58 to 66% by mass, ai2〇3: 15 to 22% by mass, B2〇3: 5 to 12% by mass' Mg〇: 〇~8 mass%, Ca〇: 〇~9 mass%, 200906755

SrO: 3 to 12.5% by mass, BaO: 0 to 2% by mass,

MgO + CaO + SrO + BaO : 9 〜 18 鼍. /. (2)

Si02: 50 to 61.5% by mass, A1203: 1〇5 to 18% by mass, B2〇3: 7 to 10% by mass, MgO: 2 to 5% by mass, CaO: 0 to 14.5% by mass, SrO: 0 to 24% by mass %, BaO: 0 to 135 mass%,

MgO + CaO + SrO + BaO : 16 to 29.5 by mass. /. (3) [Effects of the Invention] According to the method for producing an alkali-free glass of the present invention, it is possible to obtain a glass having no heat blister in the glass and having excellent uniformity and flatness. [Best Mode for Carrying Out the Invention] The glass-free material is produced by melting and molding a glass raw material containing a source of cerium, an alkaline earth metal source, and a boron source. The alkali-free glass is produced, for example, as follows. (1) Mixing a sand source, a soil-measuring metal source, and a boron source with a ratio of A120:, a clearing agent, etc., if necessary, to the composition of the target alkali-free glass. When necessary, the glass piece having the same composition as the target alkali-free glass (Π) of the glass raw material and the composition of the must-have 200906755 is continuously fed into the melting kiln from the glass raw material input port of the melting kiln to 1 500 00 to 1 600 ° C. Melt to form molten glass. The glass flakes refer to the glass cullet discharged from the manufacturing process of the alkali-free glass. (Π i ) The molten glass is formed into a predetermined thickness by a known molding method such as a float method. (iv) After the formed glass ribbon is slowly cooled, it is cut into a predetermined size to obtain a plate-shaped alkali-free glass. (矽源) 矽 sand can be used as a source of glass in the production of alkali-free glass. As long as it can be used to make glass, it can be used. The average particle diameter D5Q (equivalent particle diameter) of the cerium sand is preferably 15 to 60 μπι', more preferably 20 to 45 μm. When the average particle diameter D 5 〇 of the enamel is 15 μm or more, aggregation of the cerium sand can be suppressed, and an alkali-free glass having less bubbles and high homogeneity and flatness can be obtained. When the average particle diameter D 5 Q of the sand is 60 μm or less, the cerium is easily melted uniformly, and an alkali-free glass having less bubbles and higher homogeneity and flatness can be obtained. The average particle size is determined by measuring the particle size distribution by, for example, a laser diffraction/scattering method. (Alkaline earth metal source) An alkaline earth metal compound can be used as the alkaline earth metal source. The alkaline earth metal is, for example, one or two or more elements selected from the group consisting of Mg, Ca, Sr and Ba. Specific examples of the soil-measuring metal compound include carbonates such as MgC03, CaC03, BaC03, SrC〇3, (Mg'Ca) C03 (dolomite), or oxides of MgO, CaO, Ba〇200906755, SrO, or Mg(OH). 2, Ca(OH) 2, Ba(OH) 2 'Sr ( OH ) 2 or the like hydroxide, but in the present invention, it is preferred that some or all of the alkaline earth metal source contains an alkaline earth metal hydroxide . The content of the hydroxide of the alkaline earth metal is preferably from 15 to 100% by mol (in terms of Μ 0), preferably more than 100% by mol of the alkaline earth metal source (in terms of MO, but lanthanide alkaline earth metal element). 3 0~1 〇〇 耳 % ( Μ 0 conversion) 'better 60 to 100 mA % ( ΜΟ conversion). When the content of the above hydroxide is less than 15 mol%, when the glass raw material is melted, the unmelted amount of the SiO2 component contained in the sand is increased, and the unmelted Si〇2 is generated in the glass melt. Surrounded by this bubble, it gathers near the surface of the glass melt. Therefore, there is a difference in the composition ratio of S i ◦ 2 between the surface layer of the glass melt and the portion other than the surface layer, and the homogeneity of the glass is lowered, and the flatness is also lowered, which is not preferable. As the molar ratio of the hydroxide in the alkaline earth metal source increases, the amount of undecomposed Si 2 component in the glass raw material is lowered, so that the higher the molar ratio of the above hydrogen oxide is. As the alkaline earth metal source, specifically, a mixture of a hydroxide of an alkaline earth metal and a carbonate, a hydroxide of an alkaline earth metal, or the like can be used. The carbonate is preferably any one or more of, for example, MgC〇3, CaC〇3, and (Mg' Ca) C03 (dolomite). The hydroxide of the alkaline earth metal is preferably at least one of Mg(OH)2 or Ca(OH)2, and particularly preferably Mg(OH)2. (Boron source) Next, boron compounds as a boron source are, for example, orthoboric acid (H3B 0 3 )-10-200906755, metaboric acid (Η Β Ο 2 ), tetraboric acid (Η 2 B 4 Ο 7 ), anhydrous boric acid ( Anhydrous B2〇3) and the like. In the production of a general alkali-free glass, orthoboric acid can be used from the viewpoint of being inexpensive and easy to obtain. In the present invention, when the boron source is anhydrous boric acid, the boron source is 100 mass. In the case of /〇 (b2o3 conversion), it is preferable to contain 10 to 1% by mass (02〇3 conversion). When the anhydrous boric acid is at least 10% by mass, the aggregation of the glass raw material can be suppressed, and the effect of reducing the bubble, the homogeneity, and the flatness can be obtained. A more preferable range of anhydrous boric acid is in the range of 20 to 100% by mass. Raw boronic acid can be used from the viewpoint that it is inexpensive and easy to obtain from the boron compound other than anhydrous boric acid. (Other raw materials) Other raw materials include, for example, Al2〇3. In order to improve the meltability, the clarification property, and the formability, it may contain Ζ Ο Ο, S Ο 3, F, C 1 , and S Ο Ο 2 (glass raw materials) as a clearing agent or the like. mixture. The composition of the glass raw material has the composition of the target and becomes the composition of the alkali-free glass. The composition of the glass raw material is preferably a composition having the composition (1) to be described later as a non-glass, and particularly preferably a composition having an alkali-free glass having the composition (2) or (3) described later. (Alkaloid-free glass) -11 - 200906755 The alkali-free glass obtained by the production method of the present invention contains Si〇2 from a source and b2〇3 from a boron source. The alkali-free glass means a glass which does not substantially contain an alkali metal oxide such as Na20 or κ20. The preferred composition of the alkali-free glass will be described below. The alkali-free glass has characteristics (thermal expansion coefficient: 25\1〇-7 to 60><1〇-7/. (: 'chemical resistance, durability, etc.) as a glass substrate for a display, and is suitable for a sheet glass. From the viewpoint of molding, it is preferred to represent an alkali-free glass having the following composition (1) by mass percentage based on an oxide. In an alkali-free glass (100% by mass), S i Ο 2 : 5 0 to 6 6 %, Al2〇3: 10.5 to 22% by mass, B203: 5 to 12% by mass, MgO: 〇~8 mass%, CaO: 〇~14_5 mass%, SrO: 0 to 24 mass%, BaO: 〇~13.5 mass %, MgO + CaO + SrO + BaO: 9 to 29.5 mass% · · (1) Further, 'the alkali-free glass strain point is 64 〇t or more', the thermal expansion coefficient and the density are small, and the buffered fluoric acid for etching is suppressed ( The white turbidity caused by BHF is excellent in durability to a chemical such as hydrochloric acid, and it is easy to melt and form, and is suitable for float forming. It is particularly preferably expressed by mass percentage based on oxide, and has no alkali of the following composition (2). Glass. Alkali-free glass (1 〇〇 mass%), S i 0 2 : 5 8~6 6 mass% ' Al2〇3: 15~22 quality %, B2〇3: 5 to 12% by mass, MgO: 0 to 8% by mass, CaO: 〇~9% by mass, SrO: 3 to 12_5% by mass, BaO: 0 to 2% by mass, MgO + CaO + SrO + BaO: 9~18% by mass. (2) 〇

Si〇2 is 58% by mass or more, and the strain point of the alkali-free glass rises, and the resistance to -12-200906755 is good, and the coefficient of thermal expansion is lowered. s i 0 2 is 6% by mass or less, and the glass has good meltability and good devitrification characteristics. When A1203 is 15% by mass or more, phase separation of the alkali-free glass can be suppressed, the coefficient of thermal expansion is lowered, and the strain point is increased. A12 Ο 3 is 22% by mass or less, and the glass has good meltability. The B2〇3 system suppresses the white turbidity of the alkali-free glass caused by BHF, and the thermal expansion coefficient and density of the alkali-free glass are lowered without increasing the viscosity of the high temperature. B203 is 5% by mass or more. The alkali-free glass has good BHF resistance. B 2 Ο 3 is 12% by mass or less. The alkali-resistant glass has good acid resistance, and the strain point increases.

The MgO system suppresses the increase in the thermal expansion coefficient and the density of the alkali-free glass to improve the meltability of the glass raw material.

MgO is 8% by mass or less, suppresses white turbidity of BHF, and suppresses phase separation of alkali-free glass.

CaO improves the meltability of the glass raw material. C a 0 is 9% by mass or less, and the coefficient of thermal expansion of the alkali-free glass is lowered'. The glassy properties are good.

When SrO is 3% by mass or more, phase separation of the alkali-free glass can be suppressed, and white turbidity of the alkali-free glass of BHF can be suppressed. ..

SrO is 12.5 mass% or less, and the coefficient of thermal expansion of the alkali-free glass is lowered.

The BaO system suppresses the phase separation of the alkali-free glass and improves the meltability, and improves the vitreous properties of the glass. B a 0 is 2% by mass or less, and the density of the alkali-free glass is lowered, and the thermal coefficient is lowered.

Mg〇 + Ca〇 + SrO + BaO is 9% by mass or more. The glass is well melted. MgO + CaO + SrO + BaO is 18% by mass or less. In the composition (2), in order to improve the meltability and the clarity, the total amount of Zn〇, F, and Sn02 may be 5% by mass or less in the alkali-free glass (% by mass). Since the steps required for the treatment of the glass piece are removed, it is preferable to remove P b Ο, A S 2 Ο 3, and S b 2 0 3 in the form of impurities, etc., and it is preferable to avoid the inclusion of the impurities. The alkali-free glass of the present invention is specific to the glass substrate for display, and is excellent in resistance to reduction, homogeneity, and bubble suppression, and is expressed as a mass percentage based on oxides from the viewpoint of suitable floatation. Alkali-free glass. In the alkali-free glass (100% by mass), Si〇2: 50 to 61·5 is composed of Al2O3: 10.5 to 18% by mass, and B2O3: 7 to 10% by mass. MgO 5 mass%, 〇3〇: 0 to 14.5 mass%, 31*〇: 0 to 24 mass BaO: 〇~135 mass%, Mg〇+ Ca〇+ Sr〇+ Ba〇: 16 to 29% by volume. . . ( 3 ). S i 0 2 is 50% by mass or more. 'The acid resistance of the glass is reduced, the strain point is lowered, and the coefficient of thermal expansion is decreased. The Si02 of the Young's modulus is 6 1.5% by mass or less. The vitrification characteristics of the glass without the glass. Good A12 0 3 is 1 0.5 mass ° / ° or more 'Suppressing the phase of alkali-free glass: the property of swelling and melting glass, C1, more non-excellent forming is under [% ' : 2~ [%, .5 Quality, dense rise. it is good. From, -14 - 200906755 Increase the strain point and increase the Young's modulus. Al2〇3 is 18 mass%/. The following alkali-free glass has good vitrification characteristics, acid resistance, and B H F resistance. B2〇3 is 7% by mass or more 'The density of the alkali-free glass is lowered'. The BH F resistance is improved, the meltability is improved, and the vitrification property is improved. The thermal expansion coefficient is lowered. When Β2〇3 having the above-described effects is 9% by mass or less, the strain point of the non-inspected glass rises, the Young's modulus increases, and the acid resistance is good. When M g Ο is 2% by mass or more, the density of the alkali-free glass is lowered. 'The thermal expansion coefficient is not necessarily increased, and the strain point is not excessively lowered'. The meltability is improved. M g Ο is 5% by mass or less 'the phase separation of the alkali-free glass can be suppressed', and the glass properties, acid resistance, and B HF resistance are good. The C a lanthanide does not have to increase the density of the alkali-free glass. It is not necessary to increase the coefficient of thermal expansion, and the strain point is not excessively lowered. When C a Ο is 4.5% by mass or less, the alkali-free glass has good vitrification characteristics, a low thermal expansion coefficient, and a low density, and the acid resistance and alkali resistance are good. The S r 0 does not have to increase the density of the alkali-free glass. It is not necessary to increase the coefficient of thermal expansion, and the strain point is not excessively lowered.

SrO is 24% by mass or less, and the alkali-free glass has good vitrification characteristics. 'The coefficient of thermal expansion is lowered' and the density is lowered. The acid resistance and alkali resistance are good. B aO suppresses phase separation of alkali-free glass. It improves vitrification characteristics and improves chemical resistance. B a Ο is 13.5% by mass or less 'The density of the alkali-free glass is lowered' The thermal expansion film coefficient is lowered, and the Young's modulus is improved, and the meltability is good, and the B H F resistance is good. -15- 200906755

MgO + CaO + SrO + BaO is 16% by mass or more, and the glass has good meltability. MgO + CaO + SrO + BaO is 29.5% by mass or less, and the density and thermal expansion coefficient of the alkali-free glass are lowered. In the composition (3), in order to improve the meltability, the clearness, and the formability, the total amount of ZnO, S Ο 3 'F' Cl, and S η Ο 2 may be 5% by mass in the non-glass (100% by mass). the following. Since the processing of the glass piece requires a large number of steps, it is preferable to remove P b 0, A s 2 Ο 3, and S b 2 Ο 3 in the form of impurities, which are inevitably mixed, and it is preferable not to contain these impurities. As described above, in the method for producing an alkali-free glass according to the present invention, the alkaline earth metal source is a hydroxide using an alkaline earth metal in an alkaline earth metal source of 1% by mol (in terms of MO, but lanthanum is an alkaline earth metal element). Containing 15 to 100% of the molar % (in terms of ΜΟ conversion), the amount of SiO 2 in the glass melt is greatly reduced, and the amount of bubbles is reduced, so that segregation of SiO 2 can be improved, and homogeneity and flatness can be obtained. Alkali-free glass. The present invention uses a hydroxide of an alkaline earth metal (the hydroxide releases H20 before the liquid phase formation of the glass (about 400 ° C), so that it does not easily affect the liquid phase formation), compared to the carbonate using an alkaline earth metal (this When the carbonate is formed in the liquid phase of the glass (600 to 800 °C), when C Ο 2 is released, the amount of bubbles generated in the glass melt is reduced, and the bubbles in the glass are reduced. The alkali metal hydroxide is added so that the liquidity of the glass melt is acidic from the alkaline side, so the reactivity of SiO 2 is increased, and the amount of SiO 2 is not melted. As described above, the present invention can multiply the reduction of the amount of unmelted Si〇2 and the decrease in the amount of generation of bubbles, and obtain an alkali-free glass having excellent homogeneity and flatness. In the present invention, when the boron source is used in an amount of 10 to 100% by mass (in terms of B2〇3) containing anhydrous boric acid in a boron source of 100% by mass (in terms of B2〇3), bubbles in the glass are obtained, and homogeneity is obtained. An alkali-free glass with a higher flatness. In particular, when orthoboric acid is used as the boron source, in the presence of orthoboric acid, the cerium sand having a small particle size is easily aggregated. The agglutination of the sand is caused by the moisture contained in the glass raw material, and in order to suppress the aggregation of the sand, it is only necessary to reduce the water contained in the glass raw material. In other words, the amount of ortho-boric acid containing a large amount of water molecules in the molecule is reduced, and the amount of anhydrous boric acid is increased to obtain an alkali-free glass having less bubbles, high homogeneity and high flatness. When the glass raw material contains an alkaline earth metal compound, molten ortho-boric acid and an alkaline earth metal compound may be aggregated in the glass raw material input port of the dissolution kiln. The agglutination of ortho-boric acid and an alkaline earth metal compound loses one water molecule in the ortho-boric acid heated by the glass raw material input port, and becomes metaboric acid. The metaboric acid is liquefied at 150 ° C or higher and is brought into contact with the alkaline earth metal compound. Therefore, when anhydrous boronic acid in which the water molecules are lost by the metaboric acid is used, aggregation of the metaboric acid and the soil-measuring metal compound can be suppressed, and an alkali-free glass having less bubbles, high homogeneity and flatness can be obtained. In the method for producing an alkali-free glass of the present invention, when the above-mentioned anhydrous boric acid is used, the following effects can be obtained. (i) The amount of water in the glass raw material is suppressed, so that the heat of vaporization of water when the glass raw material is melted is reduced. By reducing the amount of heat of vaporization, the energy consumed in the melting kiln can be reduced, energy saving and productivity can be achieved. (ii) Since the water (β_〇Η) in the molten glass is reduced, the chlorine (c 1 ) contained in the clearing -17-200906755 agent is H c 1 due to the following reaction, and the volatilization can be suppressed. Thereby, the amount of the clearing agent can be reduced 'reducing the processing burden of the exhaust body containing H C1 oir + cr — HCiT + ο2 · ° (iii) the boric acid generated by the orthoboric acid losing one water molecule is easily volatilized' but the anhydrous boric acid is not easy The volatilization 'reducing the amount of boron source' can reduce the processing burden of the exhaust body containing metaboric acid. [Embodiment] [Embodiment] Hereinafter, the present invention will be specifically described by way of Examples, but the present invention is not limited to these Examples. [Experiment 1] Modulation of lanthanum source, alkaline earth metal source, boron source and other raw materials 'has a mass percentage based on oxides as 'Si〇2: 60% by mass, Al2〇3: 17% by mass, B2〇3: 8% by mass, MgO: 3% by mass, CaO: 4% by mass, S r Ο : 8 % by mass of the alkali-free glass 'as a glass mother component raw material, and then 100% of the glass raw material is vitrified % Mixed as a clearing agent C1 1 .〇% by mass as a glass raw material. The sand source is a strontium sand having an average particle diameter D 5 Q of 2 6 l·1 m and a minimum diameter to a maximum diameter of 5 to ι 〇〇 μηη. The average particle diameter D5Q was measured by measuring the particle size distribution by laser diffraction/scattering method -18-200906755 (HORIBA LA9 5 0WET). The alkaline earth metal source is as shown in Table 1. Mg(OH) 2, Ca(OH) 2, dolomite ((Mg, Ca) C03), MgC03, CaC03 and cesium carbonate compounds are shown in Table 1, hydrogen in alkaline earth metal compounds. The amount of oxide is expressed in terms of MO. The boron source was as shown in Table 1, and anhydrous boric acid (anhydrous B2〇3) or orthoboric acid (h3bo3) was used. Next, as shown in Fig. 1 (a), a glass raw material having a vitrified mass of 250 g was placed in a crucible-shaped platinum crucible having a height of 9 〇nim and an outer diameter of 70 mm. Put the crucible 14 into the heating furnace. There is no need to force stirring in the furnace. The air from the side of the furnace is blown into the dew point of 80 °C, and at the same time; [5 5 〇〇C (corresponding to the glass viscosity η is The temperature of 10 g η = 2.5 was heated for 1 hour to melt the glass raw material 12 . After the molten glass was cooled by each of the crucibles 4, as shown in Fig. 1 (b), a plate-like sample 18 having a thickness of 24 mm, a width of 35 mm, and a thickness of 1 m was cut from the central portion of the alkali-free glass 16 in the crucible 14. As shown in Fig. 2, a region of 18 mm in length and 15 mm in width at the center of the sample 18 having a length of 24 mm and a width of 35 mm (the blank of the upper side is 1.5 mm, and the space of the left and right sides is 〇mm) is irradiated with a beam of light having a diameter of 3 mm. The total length of 6 places x width 5 places 3 〇, the composition of the alkali-free glass everywhere. In the composition of 30 points, the minimum 値 of Si〇2 (% by mass) was subtracted from the maximum Si of SiO 2 (% by mass), and the composition difference (ASi 〇 2) was calculated. 5, the length of the central portion of the material 18 is 24 mm, the width of 10 mm, the maximum length of the bubbles left in the glass is 5 μmη or more, and the number of bubbles is -19-200906755. The glass of the 4 0 0 mm X tilted furnace is shown in Table 2 for the number of bubbles of 1 kg. When the glass raw material is dissolved, the residual lanthanum sand is not melted (unmelted ratio. Undissolved S i Ο 2 is a raw material of 260 g added to a platinum plate having a length of 20 mm and heated at a temperature of 800 to 1500 ° C. After an hour, it is measured by the area occupied by the strontium sand remaining in the temperature region of 1 400 to 1 500 ° C. These results are combined, as shown in Fig. 3 and Fig. 4. -20- 200906755 II i Boron source h3bo3 h3b〇3 h3b〇3 anhydrous B 2 〇3 1 anhydrous B 1 1 anhydrous b 2o3” 1 η,β〇3 1 alumina metal source I 3 _ ft M <n 醭~H Μ Ε- real鸹Ν 鸹Ν 鸹 it it S r CO ^ 03 sr ri N CNJ w inch CJ N inch n inch 03 Ν IIC a C〇3 〇10 oom ο CD W MgC03 oooo σ ο Ν fH Dolomite I U3 CM oo in no ο Ο IC a <OH> 2 〇o •H oo τΗ — ο Mg (OH) 2 10 ΙΛ OJ — C) W ΙΛ lA N »—1 CVJ »-Η ο Delete iwlS 纒fr (0 r—4 L , to ΙΛ Φ <c r- Ift <r> Λ Φ ο 1 embodiment l ] 1 embodiment 2 1 cn κ 1 Example 4 1 vr> 莩m 1 Example 6 1 1 Comparative Example 1 1 - 21 - 200906755 Table 2 △Si02 Unmelted Si02 5//m Number of bubbles above (% by mass) (%) (glass per lkg) Example 1 2. 0 18 30X10^ Example 2 1. 7 14 2 ΟΧΙΟ4 Example 3 1. 0 3 10X104 Example 4 1. 7 10 15X1 Ο4 Example 5 1. 0 8 10Χ104 Example 6 0. 5 5 5X10* Comparative Example 1 3. 0 25 5 ΟΧ 104 In Table 1, the smaller Δ S i Ο 2 is, the smaller the deviation of composition is indicated. In other words, no The homogeneity of the alkali glass is good. As shown in Table 1, Figure 3 and Figure 4, it can be seen that one part of the alkaline earth metal source uses hydroxide. Examples 1 to 6 are Δ~〇2 of 0.5 to 2.0% by mass. The weight of Si〇2 is 3~18%' and the number of bubbles is 5χ104~3〇χ 104's compared with the case of Comparative Example 1 'ASiOj, the amount of undissolved S i 02 and the number of bubbles are greatly reduced. The earth metal source uses hydroxides. Therefore, the liquidity of the glass melt is inclined from the acidic side to the alkaline side, thereby increasing the reactivity of S i 0 2 in the sand sand. As a result, the amount of undissolved S i 0 2 is reduced. It can be seen that when the boron source is used as the boronic acid (B 2 0 3 ), the amount of the unmelted s 丨 0 2 and the number of bubbles is decreased, and the homogeneity is good. When all of the alkaline earth metal source uses hydrogen oxide, the amount of ASi02, the amount of undissolved Si〇2, and the number of bubbles can be reduced. As described above, the use of the method for producing a glass of the present invention can produce an alkali-free glass which greatly improves the homogeneity of the glass and further reduces the number of bubbles while having excellent flatness. -22-200906755 [Industrial Applicability] The alkali-free glass-based glass obtained by the production method of the present invention has a small amount of bubbles, and has high homogeneity and flatness. Moreover, since it contains B2〇3, it is excellent also in chemical resistance and durability. The alkali-free glass can be used as a glass substrate for a display such as a liquid crystal display device. The entire contents of the specification, the scope of the application, the drawings and the abstract of the Japanese Patent Application No. 2007-108086, filed on Apr. 17, 2007, are hereby incorporated by reference. BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] Fig. 1 is a schematic view showing a method of producing an alkali-free glass according to an embodiment. Fig. 2 is a schematic view showing a measurement portion of a composition of a sample. Fig. 3 is a graph showing Δ S i 0 2 (% by mass) of Experimental Examples 1 to 6. 4] FIG. 4 is a graph showing the number of bubbles (number·k g _1 ) of 5 μηι or more in Experimental Examples 1 to 6. FIG. [Main component symbol description] 1 2 : Glass raw material 1 6 : Alkali-free glass -23-

Claims (1)

200906755 X. Patent Application No. 1 · A method for producing an alkali-free glass, which is a method for producing a non-alkali glass bottle by melting and forming a glass material containing a source of lanthanum, an alkaline earth metal, and a boron source. The alkaline earth metal source is used in an amount of 100% by mol relative to the alkaline earth metal source (in terms of MO, but the μ alkaline earth metal element, the same applies hereinafter), and the hydroxide containing the alkaline earth metal is 1 5 to 1 00 mol% ( 换算 conversion) By. 2. The method for producing an alkali-free glass according to the first aspect of the invention, wherein the boron source is used in an amount of 1% by mass relative to the boron source (in terms of Β2〇3), and 10 to 100% by mass of boric anhydride is contained (Β2) 〇3 conversion). 3. The method for producing an alkali-free glass according to claim 1 or 2, wherein the glass raw material is a glass raw material having an alkali-free glass having the following composition (1), which is expressed by mass percentage based on an oxide. 8102: 50 to 66% by mass, eight 12 〇 3:1 〇. 5 to 22% by mass, 82 〇 3 : 5 to 12% by mass, MgO: 0 to 8% by mass 'CaO: 0 to 14.5% by mass, S r ◦ : 0 ～ 2 4% by mass, B a 0 : 〇~1 3 _ 5 Quality °/. , MgO + CaO + SrO + BaO : 9 to 29.5 mass % (1). 4. The method for producing an alkali-free glass according to claim 1 or 2, wherein the glass raw material is a glass raw material having an alkali-free glass having the following composition (2), which is expressed by mass percentage based on an oxide. Si02: 58 to 66% by mass, Ah〇3: 15 to 22% by mass, B2〇3 ··5 to 1 2 by mass. /. , M g Ο : 〇~8 mass% ' ca 0 ·_ 〇~9 mass%, SrO: 3 to 12.5% by mass, BaO: 0 to 2 mass%, MgO + CaO + SrO + BaO : 9 to 18% by mass …(2). -24- 200906755 The mass percentage of the manufacturing method of the bismuth glass indicates the glass raw material, 0.5 to 18% by mass, %, CaO: 0 to 14_5 3. 5 mass%, 5. As in the patent application range No. 1 or 2, The glass raw material is used as an oxide: SiO 2 having an alkali-free glass having the following composition (3): 50 to 61.5% by mass, Al 2 〇 3: 1 B 2 〇 3 : 7 to 10% by mass, MgO: 2 to 5 mass%, S r Ο ·· 0 to 2 4 mass%, B a Ο : 0 to 1 MgO + CaO + SrO + BaO : 16 to 29.5 mass% (3).