TW200401757A - Glass and method for production of glass - Google Patents

Abstract

This invention provides a glass containing a reduced amount of foam, which contains none of As2O3 and Sb2O3 even if containing no SO3; and a method for producing a glass which uses none of As2O3 or Sb2O3 as a refining agent. The glass has a reduction degree corresponding to 0.61 or more of a ratio of Fe ions calculated by (Fe2+)/((Fe2+)+(Fe3+)). A method for producing a glass containing Si in a mass percentage of 40% or more in terms of SiO2, which involves melting a raw material, is characterized in that the raw material contains an ammonium salt (exclusive of ammonium sulfate and ammonium nitrate).

Description

200401757 (1) 发明. Description of the invention [Technical field to which the invention belongs] The present invention relates to silicate glass and a method for manufacturing silicate glass. [Prior art] In various applications such as glass, window glass, glass substrate for flat control panel display, glass bottles, glass cups, fluorescent glass tubes, etc., Si glass containing 40% or more of Si glass is represented by mass percentage. (Hereinafter referred to as silicate glass.) It is widely used. Among the silicate glass used in these applications, in addition to meeting the requirements for characteristic surfaces such as chemical durability, it is required to meet the problem of no large foam in each application, or allow only a few if it exists. Less than the number. In order to meet the requirements for this foam, usually, the raw material of silicate glass is a clearing agent containing a molten glass to remove bubbles from the molten glass obtained by dissolving the raw material. Known as such tinctures are oxide-based tinctures such as As203, Sb2O3, Na2S04, K2S04, CaS04, BaS04, and other sulfate-based tinctures, NaCl and the like. The requirements on the foam note vary depending on its application. Generally, glass substrates for flat panel display, especially thin film transistor-driven color liquid crystal displays (TFT-LCD), electroluminescent displays (EL), plasma displays (PDP), Plasma subsidized liquid crystal displays (PALC), field emission displays (FED), and other glass substrates are the most stringent requirements. In other words, glass substrates for flat control panel displays such as TFT-LCD glass substrates (2) (2) 200401757 are required to reduce the number of small bubbles even if the size is 1 0 // m. As the glass substrate for TFT-LCD, silicate glass (hereinafter referred to as alkali-free glass) which does not substantially contain an alkali metal oxide is used. As the tincture agent, As2S03, Sb203, or sulfate is used. Also, in alkali-free glass, NaCl is not suitable for users.

As2S03 and Sb203, especially As2S03, are those which are excellent as tinctures by removing bubbles from molten glass. However, they are extremely burdensome to the environment and are therefore required to control their use. In addition, compared with As203, the sulfate has a significantly reduced environmental load, so it is an excellent tincture. However, alkali-free glass has low alkalinity, and the solubility of S042- is also low. As a result, the removal of the bubble surface from molten glass in sulfate is more problematic than that of As203. The present invention aims to provide a method that can solve this problem, that is, a method for manufacturing silicate glass and silicate glass that do not contain one of As203 and Sb203 and have a small number of bubbles. [Summary of the invention] The present invention provides a reduction ratio of glass represented by the proportion of Fe ions. The Fe2 + / (Fe2 + + Fe3 +) is equivalent to a glass with a reduction degree of 0.61 or more. After the raw materials are dissolved, the mass percentage is displayed. The manufacturing method of Si glass containing more than 40% in terms of SiO2 is characterized by providing a glass manufacturing method whose raw material is money salt (except ammonium sulfate and ammonium nitrate) (Method A of the present invention). -5-200401757

After dissolving the raw materials, the method of manufacturing Si glass containing more than 40% of Si glass in terms of Si0 2 conversion is shown in the mass percentage display. It is characterized by providing an ammonium salt (excluding ammonium sulfate in molten glass after dissolving the raw materials). And ammonium nitrate) for glass (method B of the present invention). In addition, the glass of the present invention is produced by a melting method.

The present inventors have tested various substances and can use them as alkali-free glass clarifiers. As a result, they found that those who remove bubbles from molten glass are excellent clarifiers, and have completed the present invention. Generally, silicate glass such as alkali-free glass is made by heating the raw material to 1 000 ° C or more, dissolving it into a molten glass, and then cooling it. In addition, it is molded into a desired shape when necessary during cooling. The role of ammonium chloride in removing bubbles from the molten glass (hereinafter referred to as the "clearing effect") is considered as follows.

That is, the ammonium chloride in the raw material is sublimated at 3 3 7.8 t. Therefore, when the raw material above 1000 ° C is dissolved, ammonia gas (NH3) and hydrogen chloride (HC1) are dissociated instantaneously. Ammonia decomposes nitrogen (NO and hydrogen (H2) 〇2NH3-N2 + 3H2) at a high temperature above 1000 ° C. Although nitrogen has a low solubility in molten glass, it has a foaming reaction, so it can be expected to melt in glass bubbles The effect is to promote the expansion of the gas bubbles after the gas diffuses into the gas. The hydrogen gas is temporarily dissolved in the molten glass, and it can be expected to evaporate in a few minutes to several hours. To this end, the hydrogen gas is made from glass It is a foaming gas-6-κ i. '.Ii (4) 200401757, which promotes the bubble out and defoaming in the molten glass. The inventor detected the addition of ammonium chloride to the raw material after Raman spectroscopic analysis Glass (especially alkali-free glass) generates a large amount of hydrogen bubbles at the initial stage of dissolution. In addition, after the hydrogen is generated, the molten glass is reducing. Considering the contrasting effect between oxide-based clearing agents and sulfate-based clearing agents, It can also promote the diffusion of oxygen from the bubbles containing oxygen into the molten glass during the cooling of the molten glass.

In addition, although the hydrogen chloride produced by the decomposition of ammonium chloride is not the main responder, it has the effect of secondary reactions. Hydrogen chloride dissociates as protons (H +) and chloride ions (cr) at high temperatures above 1000 ° C, and is partially dissolved in molten glass. HC1— H + + C1—. Protons cannot be stably present in molten glass, and they react with hydroxyl groups to form water (H2O). H + + OH_ H2O.

After combining these two reactions, as a result, hydrogen chloride gas was dissolved in the molten glass as chloride ions and water was released from the molten glass. HC1 + OH--> cr + H2O. When the water diffuses and flows into the minute bubbles existing in the molten glass, the bubbles are enlarged to promote the emergence of deaerators. In addition, the / 3-OH of the silicate glass produced by using the raw material containing ammonium chloride is smaller than that of the silicate glass manufactured by using the raw material containing no ammonium chloride. Appears due to the sequence of defoaming. In addition to ammonium chloride, ammonium halide salts such as ammonium fluoride, ammonium bromide, and ammonium iodide 200401757

It also reacts with ammonium chloride in the same way, so it can be effectively used as a clear tincture. The ammonium salt of the glass constituent compound is also a valid clear tincture. Examples of such salts are ammonium borate salts such as ammonium tetraborate tetrahydrate. After the glass clarification reaction with hydrogen generated by the ammonium group, it is preferable that the remainder is not mixed with elements other than boric acid, which is a constituent of glass, and constituents, which are decomposed in water.

The organic acid ammonium salt also shows obvious clearing effect. Examples of such ammonium salts are: ammonium acetate 'ammonium formate, ammonium carbonate, triammonium citrate, diammonium citrate, diammonium citrate, ammonium fumarate, ammonium maleate, ammonium oxalate, ammonium succinate , Ammonium hydrogen tartrate, ammonium lactate, etc. The organic acid ammonium salt is a gaseous component after the high temperature oxidation reaction, and finally the solid component is not left in the glass, so it is an ideal tincture.

When using ammonium chloride, ammonium fluoride, ammonium bromide or ammonium iodide as the clear tincture agent, it can be determined that it is used by measuring Cl, F, Br, and I dissolved in glass It is the ammonium halide salt of the tincture. In addition, ammonium nitrate, ammonium sulfate, and the like did not exhibit a sufficient clearing effect. The nitrate and sulfate groups act as oxidants, and the hydrogen produced by the ammonium group hinders the clarification reaction. Therefore, as the tincture of the present invention, ammonium sulfate and ammonium salts other than ammonium nitrate are preferred. [Embodiment] [The embodiment of the invention] .8-(6) Below 200401757, the glass composition is represented by mass percentage, and the Si content in terms of Si 02 is referred to as the Si02 content or Si02. The glass of the present invention is a silicate glass, which is used in various applications as previously exemplified. Typical Si02 content is above 40% and below 80%. The glass transition temperature (T g) of the glass of the present invention is above 500 ° C, and preferably below 800 ° C. Deformation point is typically 500 ° C or higher for alkali lime ash silica glass such as window glass, or 64 ° for alkali-free glass such as TFT-LCD glass substrates. (: Above, especially above 60 ° C to 720t is preferred, and when used for PDP substrates with high deformation point glass, it is above 570 ° C and below 650 ° C. Coefficient of thermal expansion of the invention glass (measured based on JIS R3102 (1995) as a reference) When used in alkali-free glass for TFT-LCD substrates, typically 25 to 50 × 70- 71:-1 (measurement temperature range 50 ~ 350 ° C) 'High deformation point glass for pdp substrate is typically 7 5 ~ 90 X 1 0 — 7 ° C _ 1 (measurement temperature range 50 ~ 3 5 0 ° C). The invention glass contains one or more elements selected from the group consisting of typical Al, B, Mg, € &, 31 *,: 8 & and 211, eight 1203 0 ~ 350 / 〇, B2 0 3 0 ~ 25 〇 / 〇, MgO + CaO + SrO + BaO + ZnO 0 ^ 50%,

Al203 + B203 + Mg0 + Ca0 + Sr0 + Ba0 + Zn0 is 19 to 59%. The better MgO, Ca0, SrO, BaO and ZnO are 0 ~ 30%, and MgO + CaO + SrO + Ba〇 + ZnO are i% or more. Also, for example: Γ Al2 03 0 ~ 35% "Although A12 03 is not required, it may be contained up to 35%. When the glass of the present invention is used as a substrate for a TFT-LCD, typically, the mass percentage contains (7) 200401757

Si02 45 ~ 70% 、

Al2〇3 5 to 25%, B2〇3 1 to 20%, M g 〇 0 to 15%, C a 〇 0 to 15%,

SrO 0 ~ 1 5%, B a 〇 0 ~ 2 0%

Another example: "M g 〇 0 ~ 10%", MG g 〇 Although not necessary, but can also contain up to 10%. s i 〇 2 is an essential component. When it exceeds 70%, the solubility of glass will decrease and it will easily devitrify. It is preferably 68% or less, and more preferably 67% or less. When it is less than 45%, the specific gravity increases, the deformation point decreases, the thermal expansion coefficient increases, and the drug resistance decreases. The ideal is 51% or more, and the more preferable is 57% or more.

Al2O3 can suppress the phase separation of glass, and it is necessary to increase the deformation point. When it exceeds 25%, it is easy to devitrify and reduce the resistance. Ideally, it is 22% or less, and more preferably 19% or less. When it is less than 5%, the glass is liable to phase separation, and the deformation point is reduced. It is more preferably 10% or more, and more preferably 14% or more. B 2 〇3 small specific gravity, improve the solubility of glass, it is difficult to devitrify the necessary components. When it exceeds 20%, the deformation point is reduced, the chemical resistance is reduced, or the glass is significantly dispersed when dissolved, increasing the heterogeneity of the glass. The ideal is 16% or less, and the more preferable is 2% or less. When it is less than 1%, the specific gravity is increased, and the solubility of the glass is lowered, and the glass is easily devitrified. More than 3%, -10-200401757

The better is more than 6%. Although M g 0 is not necessary, it is a component having a small specific gravity and improving the solubility of glass. If it exceeds 10%, the glass phase separation 'is likely to devitrify or reduce the resistance. It is preferably 7% or less, and more preferably 5% or less. When MgO is contained, it should be contained at 1% or more. In particular, in order to maintain solubility and reduce specific gravity, it is preferable to contain more than 1%.

CaO is not essential, but it can improve the solubility of glass, it is not easy to devitrify, and it can contain less than 15%. If it exceeds 15%, the specific gravity will increase, and the thermal expansion coefficient will increase, but it will tend to be devitrified. Ideally, it is 12% or less, and more preferably 8% or less. When CaO is contained, it is preferred to contain 2% or more. It is more preferably 4% or more.

SrO is not necessary, but it can suppress glass phase separation and is not easy to devitrify, and it can contain less than 15%. When it exceeds 15%, the specific gravity will increase, and the thermal expansion coefficient will increase, but it will tend to be devitrified. Ideally, it is 12% or less, and more preferably 10 ° /. the following. When SrO is contained, it is preferable to contain 0.5% or more. More preferably, it is 3% or more.

BaO is not essential. However, it can suppress the phase separation of glass and is not easy to reverse vitrification, so it can contain less than 20%. When it exceeds 20%, the specific gravity will increase and the coefficient of thermal expansion will increase. Ideal is 10% or less, and more preferably 1% or less. Especially when weight reduction is important, it is better not to include. Particularly ideal is composed of

Si02 5 1 ~ 68%, A12 〇3 10 ~ 22%, B2O3

6 to 16%, .11. (9) 200401757

MgO 1 to 7%, CaO 2 to 12%, SrO 0 · 5 to 10%, and BaO 0 to 1%. When the glass of the present invention is used as a substrate for a PDP, a typical example includes

Si02 50 ~ 75%, Al2〇3 0 ~ 15%, B 2 0 3 0 ~ 10%, r2o 6 ~ 24% (R means Li, Na, K), R, 0 1 2 ~ 2 7 % (R 'means Mg, Ca, Sr, Ba) Zr〇2 0 to 10%. The content of R2O is the total amount of Li20 + Na20 + K20. The content of R'O is the total amount of MgO + CaO + SrO + BaO. Li20 is 0 to 3%, Na20 is 1 to 7%, K2O is 3 to 20%, and MgO is 0.5 to 7 ° /. , CaO is 0.5 to 12%, 81 * 0 is 0 to 10%, 83% is 0 to 10%. Ideal

Si02 5 0 to 70%, AI2O3 1 to 14%, B 2 〇3 0 to 3%, R2 08 to 24% (R means Li, Na, K), R-0 12 to 25% (R 'Means Mg, Ca, Sr, Ba) Zr〇2 0 ~ 6% -12-(10) (10) 200401757. The content of R20 is the total amount of Li20 + Na20 + K20. The content of R'0 is the total amount of MgO + CaO + SrO + BaO. 0 to 3% for Li20, 1 to 7% for Na20, 3 to 20% for K20, 0.5 to 7% for MgO, 0.5 to 12% for CaO, 0 to 10% for SrO, and 0 to 10% for BaO should. Better to contain

Si〇2 50 ~ 65%,

Al2〇3 2 ~ 12%, B 2 〇3 0 ~ 1%, R2〇8 ~ 1 6% (R means Li, Na, K), R'〇13 ~ 24% (R 'means Mg, Ca, Sr, Ba)

Zr〇2 0 ~ 5%. The content of R20 is the total amount of Li20 + Na20 + K20. In addition, the content of R'〇 is the total amount of MgO + CaO + SrO + BaO. Li20 is 0 to 2% 'Na20 is 2 to 6 ° / 〇, K20 is 5 to 14%, MgO is 1 to 6%, Cao is 1 to 9%, SrO is 0 to 6%, BaO is 0 to 3% is appropriate. In addition, in the glass of the present invention, Zn is an essential component, but it may be contained within 5%. Even if the glass of the present invention does not contain As203 or Sb203, it still contains NH4 +, that is, it has the characteristics of floating out of gas components such as H2 by the ammonium group, which can reduce its internal bubbles. . The reduction degree of glass is usually expressed by the content of Fe2 + and Fe3 +, and is represented by r = Fe2 ++ ((Fe2 ++ Fe3 +)), which is 0.61 or more in the glass of the present invention. When it is less than 0.61, bubbles may increase. It is preferably 0.8 or more ', more preferably 0.9 or more, and particularly preferably 0.95 or more. -13-(11) (11) 200401757 When the glass of the present invention can measure r 'using Fe ion as an index, Fe is a component which must contain a component. The Fe2O3 conversion content of Fe (total amount of Fe2 + and Fe3 +) must be 0.0015% or more. When the Fe2Ch conversion content of Fe is less than 0.0 0 15%, shellfish! Determination of J r is not easy. For easier measurement of 1 ·, the Fe2Ch conversion content of Fe is preferably 0.01% or more. What ’s Fe? A typical example of the conversion content of 02〇3 is 0.3% or less. The glass for the display should be less than 0.2%. If it exceeds 0.2%, the coloration of blue is not desirable as a glass for a display. It is preferably 0.1% or less, and more preferably 0.05% or less. The degree of reduction of the glass of the present invention can also be measured using indexes other than Fe ions. For example, the state of Fe ions can be predicted after analyzing Ti3 + ions as trace impurities by ESR (electron rotation resonance analysis). In addition, glass remelting can also effectively measure oxygen activity by glass potential measurement. ○ Light wavelengths of 400 to 700 nm are in the visible light field. Glass with absorption within this range is not suitable for glass substrates for displays. Represents the wavelength of visible light in the CRT standard (Japanese Electronic Industry Association glass characteristics specification "EIAJ ED-2138A") represented by 546nm. The glass of the present invention is suitable for substrate-like glass. When the substrate thickness is 0.7 mm, the light transmittance at a wavelength of 546 nm is preferably 85% or more (especially 90% or more). For glass substrates with a substrate thickness other than 0.7 nm, the transmittance and reflectance can be measured and converted to 0.7 mm. It is known that the ultraviolet transmittance near a wavelength of 300 nm will decrease after absorbing Fe3 +. The glass of the present invention is extremely high in the aforementioned Γ, and therefore it is easy to increase the ultraviolet transmittance. When the thickness of the substrate of the glass of the present invention is 0.7 mm, ** 14-(12) 200401757 at a wavelength of 300 nm is preferably 60% or more, and more preferably 77% or more. In the present invention, if the Fe content is 0.2% or less in terms of Fe2O3, the clarification effect is good, and the transmittance may be 80% or more. When the glass of the present invention is produced using an ammonium salt, the obtained glass contains a trace amount of NH /. The glass of the present invention containing NH / is tested as follows. (1) After crushing the glass, weigh 1 g on a platinum dish.

(2) Wet the 12 glass powder with a small amount of ion-exchanged water. (3) Add 10 W of HF (concentration: 29 mol / l) and 5 ^ of H2S〇4 (concentration. 9 mol / l) 'to the glass frit moistened with ion-exchanged water, and perform thermal decomposition on a sand bath. (4) After cooling, add 5 m £ HF (concentration · 29mol / l) 'on the sand bath to decompose it by heating. Heating was continued until the white smoke from the sulfuric acid fumes appeared to be syrupy.

(5) After cooling, the residue and the decomposed solution were washed out in a flask for Chieda distillation with ion-exchanged water. At this time, the solution capacity was 300 m £. (6) Put zeolite in the flask 'and set the flask in a Kieda distillation apparatus. (7) Put 50 2 of H2S04 (concentration: 25 mmol / l) in the measuring cylinder of the receiver of the Kieda distillation apparatus. After passing through the funnel, a 40 2 NaOH aqueous solution (concentration: Wg / 1) was added to the flask. (8) The flask is heated to a vaporized state. (9) After distilling about 140, 'stop steaming' and dilute the distillate with ion-exchanged water for 200 m. -15-(13) 200401757 (10) NH4 + in distillate was detected by ion chromatography. In the present invention, when the content of NH / in the glass is 0.0001% or more, the glass is said to contain NH /.

Also used in the “Kiyada Steamed Device” is shown in "42 · Ammonium Ion (NH4 +)" in IS K 0 1 0 2 "Workshop Drainage Test Method" (1993). The distillation sequence is based on the ammonium ion analysis method specified in "42" of JIS K01 02 and the organic nitrogen analysis method specified in "44 · Organic Nitrogen". The inventors used Dionex Corporation as the ion chromatography device. As the pre-column and the separation column, Ion-Pak CG14 Ion-Pak CS14 manufactured by Dionex was used. As the suppressor device, an automatic suppressor (recycling type) is used. As the detector, an electrical conductivity meter is used. Methanesulfonic acid (concentration: 10 mm0 / l) was used as the eluent, and the flow rate of the eluent was 1.0 m £ / m i η.

It is preferable that the content of ΝΗ4 + in the glass of the present invention is 0.0001 to 0.00%, and more preferably 0.0004% or more. The best is from 0.0004 to 0.00001. . When the glass of the present invention contains more than one element selected from the group consisting of Cl, F, Br, and I, its typical content is preferably from 0.03 to 1 ° / 〇, particularly 0.0 5 to 1%. Better. When the content exceeds 1%, when the glass of the present invention is used in a TFT-LCD glass substrate, there is a fear of reducing the deformation point or chemical resistance. The content is preferably less than 0.5%, and under the condition that the clearing effect is obvious, the content is more than 0.005%, and more than 0.08% is more preferable. The glass of the present invention does not contain S, or even if it contains S, its S03 conversion content is only -16-(14) 200401757 is preferably 0.005% or less. If the conversion content of S03 exceeds 0.005%, the reduction degree of the glass will be reduced and the clearing effect will not be obtained effectively. Or, the re-boiling of S03 may increase the generation of bubbles. Or even if the content of S is small, the coexistence of S with Fe2 + or Fe3 + produces amber coloration, and it may not be used as a glass substrate for a flat control display. In order to prevent coloring, the ideal conversion content of S03 is 0.002% or less, more preferably 0.0005%.

None of the glasses of the present invention contains As and Bb, or even if As or Sb is contained, the total content of the AhO3 conversion content and the Sb203 conversion content is preferably 0.1% or less. More preferably, it is less than or equal to 0.1%. The glass of the present invention does not contain Sn, or even if it contains Sn, its Sn02 conversion content is only 0 · 0 2 y. The following are appropriate. When it exceeds 0.02%, the reduction degree of glass such as ammonium chloride may become small, or Sn may be present in the colloidal glass, and the glass may be colored, and it may not be easily used as a glass substrate for a flat control display. The glass of the present invention does not contain oxides such as Ti, V, Nb, Mo, Ce, etc.

should. These oxides release oxygen in the reduced glass. Therefore, the degree of reduction may be reduced after the saddle chloride, or the glass may be colored with metal ions, and it may not be easily used in a glass substrate for a flat control display. The glass of the present invention is preferably one that does not contain Se, Cu, Pb, Ni, Cd, Mn, Ge, Cs, and the like. These elements are present in the glass after being in the form of a metal colloid, so that the glass may not be used as a glass substrate for a flat control display. The glass of the present invention is represented by mass percentage, which is a glass containing 40% Si0 2 in terms of Si0 2, containing Nh4 + or c, but not containing S (or even if S is contained, it is represented by mass%.) The conversion content is only 0.005% to -17-(15) (15) 200401757 or less, and neither As nor Sb is included (or even if As or Sb is included, represented by mass percentage, the total As2 03 conversion content and Sb203 conversion content total It is only 0.1% or less), and it does not contain Sn '(or even if it contains Sn in terms of mass percentage, its content of Sn02 conversion is only 0.02% or less). Among them, Si is Si. 2Converted content is 80 ° / under the mass percentage. The following are appropriate. NH4 + is preferably 0.000 1 to 0.01% in terms of mass%, especially 0.04 to 0.01 0% is the best. One or more kinds of elements selected from the group consisting of C1, F, Br, and I are represented by mass% and represented by 0.03 to 1 ° /. It is preferred, especially C1 containing 0.05 ~ 1% is the best.

In addition, it contains one or more elements selected from the group consisting of Al, B, Mg, Ca, Sr, and Ba & Z group, and the representative mass percentage of the following oxide conversion is Al203: 0 to 35%, and B203. 0 to 25%, MgO + CaO + SrO + BaO + ZnO · 0 to 50%, Al203 + B203 + Mg0 + Ca0 + Sr0 + Ba0 + Zn0 is preferably 19 to 59%. The glass is Si02: 45 to 70%, Al203 to 5 to 25%, B203 to 1 to 20%, MgO: 0 to 10%, CaO: 0 to 15%, and SrO: 0 to 15 %, BaO: 0 to 20%, or Si02: 50 to 75%, AI2O3: 0 to 15%, B2O3: 0 to 10%, R20: 6 to 24% (R stands for Li, Na, K), ΙΓ〇: 12 to 27% [R · stands for Mg, Ca, Sr, Ba), Zr0: 0 to 10%. Ο 'and NH / to contain o.oooi ~ o.oi%, and Cl is Contains 0.05 ~ 1% of the glass is appropriate. The glass of the present invention is produced by the methods A and B of the present invention. • 18- (16) 200401757 The method A of the present invention will be described. It is heated to obtain the original half hopper blended with the silicate glass of the target composition, and then dissolved into molten glass. This molten glass is degassed, homogenized, and the like, and then post-cooled. The homogenization of the molten glass can also be promoted by stirring. In addition, plate glass and the like are generally formed while cooling. This raw material is usually made of silica sand or the like, and may also contain cullet (broken glass).

The dissolution is carried out by placing the raw materials in a suitable crucible, or in an electric furnace such as an electric furnace maintained at a high temperature by the crucible. The raw materials can also be continuously put into glass maintained at a high temperature of 1 500 ~ 1 600 ° C. It is carried out in molten tincture. The method A of the present invention uses the ammonium salt of the excellent elixirs described above, such as a raw material containing ammonium chloride.

The proportion of ammonium chloride in the raw material is preferably 0.1 to 10 parts when the mass of the glass obtained by dissolving the raw material is 100 parts. That is, ammonium chloride is equivalent to 0.1 to 100 parts per 100 parts of the dissolved raw material. It is advisable to add 10 parts of glass raw materials. If it is less than 0.1 parts, it may reduce the clearing effect of ammonium chloride. More preferred is 0.2 or more. When the glass is maintained in a molten state for a long time, the content ratio is preferably 0.3 parts or more, and more preferably 1.0 part or more. When the content ratio exceeds 10 parts, there is a possibility that a large amount of ammonia gas, hydrogen chloride gas, chlorine gas, or other gas may be generated during dissolution. The better is 3 or less. In addition, after dissolving, the glass containing NH / and C1 was obtained, but the amount was extremely small. Therefore, when calculating the amount of the raw material added to ammonium chloride, 'the mass of the glass containing ΝΓΓ and C1 was performed as 100 parts. It does not matter to the calculator. -19-(17) 200401757 The raw material does not contain sulphate, or even if the total content of sulphate is contained in the raw material, it is only 0. 01 or less when obtaining the glass quality after dissolving the raw material in 100 parts. When the mass of the glass is obtained after 0 parts of the raw materials are dissolved, it is preferable to add less than 0.1 parts of sulfate to the glass raw materials. If it exceeds 0 · 0 1 part, it may reduce the clearing effect of ammonium chloride. Or it may not be used as a glass substrate for displays.

Also, when using a small amount of sulfate as a clarifying agent, the glass containing S 0 3 derived from sulfate is obtained after the dissolution, but it is extremely small. Therefore, when calculating the amount of raw materials for sulfate, It is not necessary to calculate 100 parts of glass such as s 0 3. The same applies to the following As, Sb, and Sn02. That is, when using a small amount of As, Sb, Sn02, etc., the glass containing as, Sb, Sn02, etc. is obtained after dissolving, but the amount is extremely small. Therefore, when calculating the amount of raw materials for As, Sb, Sn02, etc., it will contain As, Sb, Sn02 and other glass masses can be calculated as 100 parts.

None of the raw materials contain As and Sb, or even if As or Sb is included, the total As203 conversion ratio and Sb203 conversion ratio are 100 parts. After the dissolved raw materials, 0.1 or less of glass quality is obtained, that is, As203 conversion contains When the total content of the ratio and the conversion ratio of Sb203 is 100 parts of the glass obtained by dissolving the raw material, it is advisable to add an amount equal to or less than 0.1 part to the glass raw material. The raw material does not contain Sn02, or even if it contains Sn02, the total content of the raw material is only 100 parts. Dissolving the raw material to obtain the glass mass of less than 0.03 parts, that is, Sn02 is added to the glass raw material to obtain 100 parts of the dissolved raw material. Glass-20-(18) 200401757 Mass of 0.03 parts or less, especially 0.002 parts or less is more preferred. Exceeding 0.002 parts, especially exceeding 0.03 parts will reduce the clearing effect of ammonium ammonium. The raw materials may contain fluorides and chlorides other than ammonium chloride. For example, after using ammonium chloride and rhenium chloride hydrate (S r C 12 · 6 Η 20) or barium chloride hydrate (BaCh · 2 Η 20), C1 in the glass can be increased while maintaining a certain degree of reduction. content.

The glass of the present invention can be produced by the following method A of the present invention. That is, the raw materials of each component of the glass of the present invention are used to prepare the target composition, and the raw materials are prepared. The molten glass is prepared by continuously dissolving it in a glass melting tin with a maximum temperature of 1500 to 160 ° C. In addition, an appropriate amount of chlorinated chloride is added to this raw material. The molten glass is then degassed for 1 200 to 1 500 t, or degassed by a degassing technique under reduced pressure.

The defoamed molten glass is formed as sheet glass. Examples of molding methods are: floating method, melting method, rip-down method, etc. After the plate glass is cooled and cut, glass substrates for TFT-LCD and glass substrates for PDP are produced. The method B of the present invention will be described below. In the method of the present invention, after the ammonium chloride is contained in the raw material, NH4 + is contained in the molten glass, that is, the H2 gas and other gases are calculated to be generated. It is calculated that those containing N 含 Γ in the molten glass, that is, those in which H 2 gas is generated and other gases are characteristic. As a method of directly supplying ammonium chloride and molten glass, for example, a method of spraying molten glass powder on the surface of the molten glass is exemplified. -21-(19) 200401757 Also in the method B of the present invention, it is also equivalent to the description of sulfate and Sn02 in the method a of the present invention. The method B of the present invention can also be used in combination with the method a of the present invention. By mistake, the method A and method B of the present invention can produce alkali-free glass with a small number of bubbles even without using oxide-based clearing agents such as As 2 0 3 and Sb203, and sulfate-based clearing agents. [Example]

Si02 ~ Fe203 in Table 1 are those obtained when the total amount of Si02 ~ BaO components of the glass in the examples of the present invention is made to 100, and the amount of glass salt / chloride ~ S03 represents the amount of glass raw material added. Wait. In addition, the composition of the glass raw material used in this example is almost the same as the composition of Si02 to Fe2 03 in Table 1 (b203 is dissolved in about 1/3 during dissolution). Table 2 represents the characteristics of the glass in this example.

The total of the columns Si02 ~ Ba0 in Table 1 is 100, and after blending industrial raw materials which do not contain sulfates with the composition shown in the mass ratio, 250 g of titanium oxide, ammonium salt (ammonium chloride), and chloride (chlorine) are prepared. Sulfonium hydrate) or sulfate (calcium sulfate) as the raw material. In addition, the content of iron oxide, chloride, or sulfate represents the Fe2O3 conversion content, C1 content, SO :, content of Fe in the mass ratio of Si02 ~ Ba0 in the preceding table as 100, respectively. The amount of C1 content conversion of ammonium chloride was input. In addition, when the glass mass is made into 100 parts, the ratio of the ammonium salt in the raw material to that in Table 1 is substantially the same. In the table, "one" means "not included" and "not" means "not determined". -22- (20) 200401757 In addition, the oxides of Ti, V, Nb, Mo, and Ce are not substantially contained in the examples of the present invention. Also, Se, Cu, Pb, Ni, Cd, Mη, Ge,

Cs is essentially not included. Place 250 grams of raw materials in a platinum crucible, and use an electric furnace in the atmosphere, at 1 600 ° C in Examples 1 ~ 3, 5 ~ 7, and at 1 50 ° C in Example 4, respectively. Hours, melted into molten glass. This molten glass was solidified after flowing out of the carbon plate, and then gradually cooled.

The r of the glass obtained, the amount of dissolved NH / (unit: 10-4%), the amount of dissolved C1 (unit:%), / 3-OH (unit: mm-D, the number of bubbles (unit: unit / cm3)) In addition, the dissolved NH / amount was not determined for Examples 4 to 7. r: Quantitative determination of Fe2 + in glass by bipyridine absorption spectrometry Quantitative analysis of total Fe ions, ie, Fe2 + + Fe3 by ICP emission spectrophotometry. ＋。 It is obtained after +. Moreover, r of Example 6 has not been measured and is estimated to be 0.6 〇.

ί Gucun C 1 li · After the glass was crushed, it was measured by the Yingguang X-ray method. It was not measured for Example 5. Β — 〇 Η • Measure the infrared transmittance and calculate it by dividing the transmittance of 3 5 7 0 c m — 1 by the transmittance of 4000c — 1. In addition, the measurements were not performed for Examples 5 and 6. Number of bubbles: After cutting and honing the glass, make a glass plate with a thickness of 2mm. Under a solid microscope, count the number of bubbles above about 10 // m, and divide it by the volume of the glass plate. In this evaluation, the evaluation is performed. Hours of dissolution and retention of bubbles in the glass. The number of air bubbles is preferably 1,000 or less / cm3, and more preferably 500 or less / cm3. -23- (21) 200401757 By increasing the dissolution time, the number of bubbles decreased sharply. In this evaluation, when the number of air bubbles is 2,000 / cm3 or less, the number of air bubbles after being dissolved for 6 hours under the same conditions is 1 or less / cm3. In this evaluation, when the number of bubbles is 100 or less / cm3, the number of bubbles after 6 hours of dissolution can be reduced to a substantially zero number of bubbles. In this evaluation, when the number of bubbles is 5,000 or less / cm3, the number of bubbles can be reduced to substantially zero when a large number of continuous dissolutions are carried out. The dissolution time in the floating method is usually 6 hours or more.

Transmittance: For example: ~ 3 After cutting the glass and honing the glass, a plate glass having a thickness of 0.7 mm is made, and the non-existing part of the bubble is selected to measure the spectral transmittance. The measurement was performed using a U-3500-type self-recording spectrophotometer manufactured by Hitachi to determine transmittances (%) at 546 nm and 300 nm. The specific gravity, coefficient of thermal expansion and glass transition temperature (Tg), deformation point, Young's rate, and HC1 resistance are 5,000 g of glass with the same composition and the same raw materials as in Examples 3 to 5 in a crucible at 1 600 ° C. After dissolving for 6 hours, a glass sample having bubbles completely removed from the glass was prepared, and then measured.

Specific gravity: It is measured by Archimedes' method. Coefficient of thermal expansion and Tg: The coefficient of thermal expansion (17 ° C _ 1 (measurement temperature range: 50 to 350 ° C)) was measured by the indicated thermal expansion meter (TMA). Read Tg (t) from the temperature of the inflection point of the thermal expansion curve. Deformation point: The deformation point (° C) was measured by the fiber elongation method (nS R3103-2 2001). Young's rate: After making glass (50mmx50mmx10mm) with a thickness of 10mm, the Young's rate (GPa) was measured by the ultrasonic pulse method. Resistance to HC1 ·· Immersion at 90 ° C / 1 hydrochloric acid at 90 ° C -24-(22) 200401757 After 20 hours of immersion, the mass reduction per unit area is obtained from the change in the surface area of the glass and the quality of the impregnated glass. The content of Si02 ~ Fe203 in the obtained glass is extremely small in terms of the mass ratio of components other than Si02 ~ BaO. Therefore, it is equivalent to the one calculated from Table 1 Si02 ~ Fe203. For the impurities in the glass of the glass of Example 3, that is, the elements other than those listed in the table, were induced by a plasma mass spectrometer (ICP-MS;

Ag 1 i Ent Co., Ltd. 7500 s) for qualitative analysis. Quantitative analysis of the quantitative elements detected by I c P-M S was performed by the standard addition method. As a result, those having the highest concentration of impurity element Tm of 45 ppm, followed by Pb of 1.5 ppm, and Ni of 1.1 ppm, and those whose impurities were all less than 1 ppm were judged to be substantially free. As, Sb, and Sn are all below the quantifiable limit. Quantitative analysis of S03 by fluorescent X-ray method was 8 ppm (0.0008%). The amount of dissolved SCh in glass of Example 7 was 0.001%.

Examples 1 to 5 are examples of the method A of the present invention, and examples 6 and 7 are comparative examples. Among the raw materials of Examples 1 to 5, those containing clarifying agents were those containing ammonium chloride, and those of S03 were substantially not contained. In addition, As and Sb are also substantially not included. The glass contains both NH / and C1. The glasses of Examples 1 to 5 are suitable for TFT-LCD glass substrates. The results of Examples 1 to 3 proved that the amount of C1 dissolved in the glass increased as / 3 -OH decreased. The increase in the proportion of ammonium chloride in the raw materials and the increase in H2O released from the molten glass at the same time. In addition, as the proportion of ammonium chloride in the raw material increases, r also increases, and the number of bubbles is reduced as ′ -25-(23) 200401757.

The clarifying effect in the present invention depends on the composition of the glass. Generally, the composition of the alkali earth metal oxide (Mg0, Ca0, Sr0, Ba〇) in the alkali-free glass has a smaller total amount, and a less clarifying agent. Adding amount can achieve a clear effect. This is because the present invention obtains clear water by the action of hydrogen. Therefore, the composition with a small amount of oxygen activity in the glass, that is, the composition with a small total amount of alkaline earth metal oxides has a clear effect. The glass of Examples 1 to 3 is converted to Mohr%, and it contains 11.7% of alkaline earth metal oxides. However, Example 4 is 14.5%, Example 5 is 12.3%, especially Examples 3 and 1. The difference in the number of bubbles in 4 is due to this effect. The content of alkaline earth metals is preferably less than 20%, particularly preferably less than 15%, and more preferably less than 12%.

(24) 200401757 Table 1 Example 1 2 3 4 5 6 7 Si02 64 64 64 60 58.9 64 64 Al2〇3 17 17 17 17.3 16.1 17 17 B 2 0 3 8 8 8 8 8.6 8 8 MgO 1.4 1.4 1. 4 3 .1 0.8 1.4 1 .4 CaO 6.2 6.2 6.2 3.6 4.3 6.2 6.2 SrO 3.4 3.4 3.4 7.9 1 .9 3.4 3.4 BaO 0 0 0 0. 1 9.4 0 0 F e 2 〇3 0.07 0.07 0.07 0.07 0.02 0.07 0.07 Ammonium salt / Chloride NH4C1 Ν Η 4 C 1 nh4ci nh4ci nh4ci nh4ci SrCl2 · 6H20 Ammonium salt addition 0.75 1.06 1.5 1 1.5 1 0.98 0.75 — nh4 + 0.25 0.36 0.5 1 0.5 1 0.33 0.25 not Cl 0.5 0.7 1 1 0.65 0.5 1 sulfate — One — — One Ca S 0 4 One S〇3 Not yet Not yet 0.2 Not yet 27-(25) 200401757 Table 2 Example 1 2 3 4 5 6 7 Γ 0.80 0.97 0.99 0.97 Not dissolved 0.6 nh4 + 4 6 8 Not yet undissolved Cl 0.12 0.15 0.2 0.3 Not 0.1 0.18 Soluble S〇3 Not 0.0008 Not yet 0.001 β-OH 0.27 0.25 0.22 0.24 Not yet, 0.28 Number of bubbles 1000 200 20 500 300 2000 3 400 Transmission (546nm ) 9 1.3 90.8 90.4 Transmission rate (300 nm) 63.4 77.7 87.9 Specific gravity 2.42 2.50 2.5 4 Coefficient of Thermal Expansion Co. 33 38 39 Co. Tg Co. 742 728 726 Co. Deformation Point Co. 690 670 670 Co. Young's Rate Co. 75 76 70 Co. HC1 Resistance Co. 0.06 0.13 0.08 Co.

The SiO2 ~ Fe203 in Table 3 are those obtained when the total SiO2 ~ BaO components of the glass obtained in the embodiment of the present invention are made to 100, and the ammonium salt ~ NH / represents the amount of glass raw materials added. In addition, the composition of the glass raw material used in this example is almost the same as that of SiO2 to Fe203 in Table 3 (B2Ch is about 1/3 in the dissolution during dissolution). Table 4 shows the characteristics and the like of the glass in this example. The total of Si02 ~ Ba0 in Table 3 is shown in a mass ratio of 100. 28-(26) 200401757 Composition and blending of industrial raw materials that do not contain sulfates, in which iron oxides and ammonium salts ( 250 g of ammonium bromide, ammonium iodide, ammonium tetraborate tetrahydrate, diammonium hydrogen citrate, or ammonium sulfate). The ammonium salt was made into a total mass ratio of 100 to SiO 2 to Ba 0, and NH / amount was added in an amount of 0.25 parts. In addition, the ratio of the ammonium salt content in the raw material when the glass mass is 100 is substantially the same as that in Table 3.

The 250 g of the raw material was placed in a crucible of a forceps, and the molten glass was prepared by dissolving the raw material in an electric furnace at 1 600 ° C for 1 hour. This fused glass is solidified and cooled gradually after the carbon plate flows out. Measure the number of glass bubbles obtained in the same way as in Table 1. The content of Si02 ~ Fe2O3 in the obtained glass is extremely small, and the mass ratio of components other than Si02 ~ BaO is equivalent to that calculated from Table 3 Si02 ~ FeCh.

-29-(27) 200401757 Table 3 Example 8 9 10 11 12 Si02 64 64 64 64 64 Al2〇3 17 17 17 17 17 B 2 0 3 8 8 8 8 8 MgO 1.4 .1.4 1.4 .1.4 1 .4 1 .4 CaO 6.2 6.2 6.2 6.2 6.2 SrO 3.4 3.4 3.4 3.4 3.4 BaO 0 0 0 0 0 F e 2 〇3 0.03 0.03 0.03 0.03 0.03 0.03 Ammonium salt NH4Br nh4i (NH4) 2B4〇7 • 4H20 (nh4) 2hc6h5o7 (nh4) 2so4 Ammonium salt addition amount 1.3 8 2.04 1.86 1.59 0.93 nh4 + 0.25 0.25 0.25 0.25 0.25 Table 4 Example 8 9 10 11 12 r 0.86 0.83 0.79 0.83 0.45 Number of bubbles 300 100 80 600 4000 Tables 5 and 6 represent the implementation of glass substrates for PDP example. Table 5 Si02 ~ Fe2 03 are examples of the present invention when the total mass ratio of each component when glass Si02 ~ K20 components are made to 100, and ammonium salt ~ ΝΗ, representing the ratio of 30. (28) 200401757 to glass raw materials. Add amount and so on. In addition, the composition of the glass raw material used in this example is almost the same as the composition of Si02 to Fe203 in Table 5 (B203 is 1/3 of the volatilization in dissolution). Table 6 shows the characteristics and the like of the glass in this example. The implementation methods are the same as those in Tables 1 and 3. In addition, when the mass of the glass is made to 100 parts, the ratio of the ammonium salt in the raw material and the mass ratio of the ammonium salt in Table 5 are substantially the same.

The content of Si02 to Fe203 in the obtained glass is extremely small in terms of the mass ratio of components other than Si02 to K20, and is therefore equivalent to that of Si02 to Fe203 in Table 5. In addition, r and the dissolved NH / in Table 6 were not measured, and r was estimated to be 0.96-0.99, and the dissolved NH / was 5 × 10-4% or more.

-31-(29) 200401757 Table 5 Example 13 Si02 57.8 Al2〇3 6.9 B 2 0 3 0 MgO 2.0 CaO 5.0 SrO 7.0 BaO 8.0 Zr02 3.0 Li2〇0 Na2〇4.3 K2〇6.0 Fe2〇3 0.10 Ammonium salt (nh4) 2hc6h5o7 Addition of ammonium salt 3.19 nh4 + 0.15 (30) 200401757 Table 6 Example 13 r Undissolved nh4 + Unβ-OH Unbubble number 50 Transmission (546nm) Untransmittance (3 00nm) Unspecific gravity 2.77 Thermal expansion coefficient 83 Tg 620 Deformation point 570 Young's rate 76 HC1 resistance < 0.0 1

[Industrial Applicability] When the present invention does not contain As203 and Sb203, and S03 is not contained, a glass with few bubbles can be obtained. This glass is suitable for glass substrates for displays (especially glass substrates for TFT-LCD). Further, a glass having few bubbles can be obtained by dissolving raw materials not containing As203 and Sb203. It is especially suitable for the production of alkali-free glass for TFT-LCD glass substrates. -33-

Claims (1)

(1) 200401757 Scope of patent application K A glass whose characteristics are represented by the ratio of Fe ions to the reduction degree of the glass' Fe2 + + (Fe2 + + Fe3 +) which is equivalent to a reduction degree above 0.61. 2. The glass according to item 1 of the scope of patent application, wherein the glass is expressed as a percentage by mass, and contains glass containing more than 40% of Si in terms of Si02 and 0.00l5% of Fe in terms of Fe2O3. , Fe2 + / (Fe2 + + Fe3 +) is 0.8 or more, and includes NH / or C1. 3. If the glass of the first or second item of the scope of patent application, the glass is expressed by mass percentage, and the Fe content in terms of Fe203 is 0.3% or less. 4. For the glass in the scope of patent application item 3, where the glass is expressed as mass percentage, the Fe content in terms of Fe203 is more than 0.0015% and less than 0.2%. 5. For the glass of any one of the items 1 to 4 of the scope of patent application, wherein the glass is expressed as a percentage by mass and contains 0,000 1 to 0. 01%. ΝΗ / 者. 6. For example, the glass in the scope of the patent application No. 5 wherein the glass is expressed in terms of mass percentage and contains 0.0004% to 0.0001% of ΝΗ4 +. 7. The glass according to any one of the items 1 to 6 of the scope of the patent application, wherein the glass contains at least 0.3% to 1% of one selected from the group consisting of Cl, F, Br, and I in terms of mass percentage. Elements of the. 8. The glass according to item 7 of the scope of patent application, wherein the glass is expressed by mass percentage and contains 0.05 to 1 ° /. C1. 9. If the glass of any one of the items in the scope of patent application No. 1 to No. 8-34-(2) (2) 200401757 ', where the glass is expressed in mass percentage, its Si02 conversion content is 80% Si person. 10. The glass as claimed in item 9 of the patent scope, wherein the glass contains 40 to 80% SiO2 as a percentage of the temporary amount. 1 1 · If the glass in any one of the items 1 to 10 of the scope of the patent application, the glass does not contain S, even if S is contained, the S03 conversion content is only 0.005% or less in terms of mass percentage. . 1 2. The glass of any one of items 1 to 1 丨 in the scope of the patent application, wherein the glass does not contain As and Sb, or even if it contains as or Sb, its As203 conversion content is converted to Sb203. The total content is expressed by mass percentage and is only 0.1% or less. 1 3 · If the glass of any one of the scope of the patent application No. 丨 to No. 12 'wherein the glass does not contain Sn, or even if it contains Sll, its Sn02 conversion content is expressed as mass percentage is only 0. 〇2% or less. 14. The glass according to any one of claims 丨 to 13 of the scope of the patent application, wherein the glass contains at least one element selected from the group consisting of Al, B 'Mg, Ca, Sr *, Ba, and Zn, The mass percentages in terms of oxides shown below are Al2O3: 0 ~ 35%, B2O3: 0 ~ 25%, Mg〇 + CaO + SrO + BaO-f ZnO: 0 ~ 50%, A1203 + B2〇3 + MgO + CaO + SrO + BaO + ZnO: 19 to 59%. 1 5 · The glass according to item 14 of the scope of patent application, wherein the glass contains, by mass percentage, Si0 2 45 to 70%, Al 2 0 3 5 to 2 5%, 200401757 (3) B 2 0 3 1 to 20%, MgO 0 to 10%, CaO 0 to 15%, SrO 0 to 15%, BaO 0 to 20%. 16. The glass according to item 14 of the scope of patent application, wherein the glass contains Si02 50 to 75%, Al2O3 0 to 15%, B2O3 0 to 10%, R2 06 to 2 in mass percentage. 4% (R means Li, Na'K), R, 0 1 2 to 27% (R 'means Mg, Ca, Sr, Zr0 2 0 to 10%. 17 · The glass according to any one of the items 1 to 16 of the scope of patent application, wherein the light transmittance at a wavelength of 546 nm when the thickness of the substrate is 0.7 mm is 85% or more. 18. The glass according to any one of the items 1 to 17 of the scope of patent application, wherein the glass having a wavelength of 300 nm and a UV transmittance of 60% when the substrate thickness is 0.7 mm is made. 1 9. A method for manufacturing glass, which is characterized in that after dissolving raw materials, it is a manufacturing method containing 40% or more of Si glass in terms of Si0 2 in terms of mass percentage. Excluding) * 36-(4) 200401757 20. — A glass manufacturing method characterized by dissolving raw materials in terms of mass percentage and converting it to Si0 2 conversion to a manufacturing method containing more than 40% Si glass, obtained from the dissolved raw materials Those who supply ammonium salts (except ammonium sulfate and ammonium nitrate) in molten glass. 2 1. The glass manufacturing method according to item 19 to item 20 of the scope of patent application, wherein the ammonium salt (except ammonium sulfate and ammonium nitrate) is equivalent to 0 when the mass of the glass obtained by dissolving the raw materials is made to 100 parts. · It is added to glass raw materials in an amount of 1 to 10 parts. 22. The method for manufacturing glass according to item 21 of the application, wherein the ammonium salt is one or more ammonium salts selected from the group consisting of ammonium halide salts, ammonium borate salts, and organic acid ammonium salt groups. 23. The glass manufacturing method according to item 22 of the application, wherein the ammonium salt is ammonium chloride. 2 4 · If the method for manufacturing a glass according to any one of items 19 to 23 in the scope of patent application, wherein the sulfate is not added to the glass raw material, or the mass of the glass obtained after dissolving the raw material is made into 100 parts, Sodium sulfate is added to the glass raw material in an amount equivalent to 0.01 parts or less in terms of S03 conversion. 25. If the glass manufacturing method according to any one of claims 19 to 24 in the scope of the application for a patent, wherein As and Sb are not added to the glass raw material, or 100 parts of the glass mass obtained after dissolving the raw material is made, use As2. In terms of 3 and sb203, As and Sb are added to the glass raw material in an amount equivalent to 0.1 part or less. 2 6 · For the glass a. 37- (5) 200401757 according to any one of the scope of application for patents Nos. 19 to 25, in which Sn02 is not added to the glass raw material, or the glass is obtained after dissolving the raw material When the mass is 100 parts, SnCh is added to the glass raw material in an amount equivalent to 0.03 part or less. -38-200401757 柒, (1), the designated representative figure in this case is: None (II), the component representative symbol of this representative figure is simply explained: None 捌 If there is a chemical formula in this case, please disclose the chemical formula that can best show the characteristics of the invention: None -3-