Soda-lime silica glass with high visible light transmittance

Abstract

To provide: a glass sheet having soda-lime-silica glass composition with a high visible light transmittance (LtC) of at least 89% with a dominant wavelength (DW) from about 490 to 505 nanometers and purity (Pe) of 1% or less for control of thickness of about 5.66 mm; and methods of making the same.SOLUTION: The glass composition comprises a low iron raw material, a total iron oxide (Fe2O3) from 0.02 to 0.06 wt.%, ferrous (FeO) from 0.006 to 0.02 wt.%, redox of (FeO / Fe2O3) from about 0.30 to 0.55, Cr2O3 from about 0.3 to 10 ppm, TiO2 from about 50 to 500 ppm, SnO2 from about 10 to 500 ppm, and a critical amount from about 0.10 to 0.25 wt.% of SO3. The low content of iron oxide is achieved by the partial substitution of regular raw materials by low iron raw materials, with a complete substitution of regular dolomite with a low iron dolomite with a maximum content of 0.020 wt.% Fe2O3.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Background of the Invention Technical field to which the invention belongs The present invention describes a soda-lime silica glass having high visible light transmittance, having a visible light transmittance of at least 89%, a dominant wavelength (DW) of about 490 to 505 nanometers, and a purity (Pe) not exceeding 1% for a thickness of 5.66 mm, primarily for use in any presentation (interior, exterior, glazing, with or without coating) in the building industry, but not limited to other applications such as the automotive industry or appliances. [Background technology]

[0002] Explanation of related technologies Transparent glass holds great importance in the construction industry due to its main characteristics, such as high purity and faithful reproduction of colors seen through it. It is commonly used in furniture, shop windows, exteriors, and interiors. Even thick glass maintains a high visible light transmittance.

[0003] To achieve a more accurate representation of objects seen through glass, and at a lower cost than currently available commercially, there is a demand for transparent glass with high visible light transmittance.

[0004] Transparent glass compositions can be produced in various ways. In certain situations, transparent glass is manufactured using raw materials with low iron oxide content. Some glasses use tin oxide, sodium nitrate, and / or cerium oxide as reducing or oxidizing agents to achieve a specific redox ratio, and cobalt and chromium as coloring agents. Others do not contain sodium sulfate to avoid the formation of polysulfides and yellowing, and some use cerium oxide as a decolorizing agent.

[0005] Dolomite is an anhydrous carbonate mineral containing calcium magnesium carbonate. It crystallizes in the trigonal rhombohedral crystal system and forms colored crystals. In the solid state, there are ancylite mainly composed of iron and kutsnohorite mainly composed of manganese, and the presence of trace amounts of iron results in crystals with yellow to brown color tones.

[0006] Iron may exist in two different oxidation states in glass (silica - sodium - calcium). Fe 2+ exists as ferrous iron (FeO), and Fe 3+ exists as ferric iron (Fe2O3) in the glass. Each ion has different properties. Ferrous iron ions have a broad and strong absorption band centered around 1050 nm, reducing infrared radiation. Also, this absorption band extends into the visible light region, decreasing the light transmittance and giving the glass a bluish color tone. Ferric iron ions have a strong absorption band in the ultraviolet region, preventing glass transmission, and furthermore, having two weak absorption bands at 420 - 440 nm in the visible region, slightly reducing the light transmittance and coloring the glass yellow.

[0007] The balance between ferrous iron and ferric iron directly affects the color and transmittance characteristics of the glass.

Number

[0008] The iron oxidation - reduction (redox) ratio is the value obtained by dividing the amount of ferrous iron (FeO) by the total iron (Fe2O3). That is, the more ferric iron ions (Fe 3+ ) there are in the glass, the higher the ultraviolet absorption rate, the higher the light transmittance, and the yellower the color. However, when the amount of ferrous iron ions (Fe 2+ ) increases due to the chemical reduction of Fe2O3, the infrared absorption rate increases, but the ultraviolet decreases and the light transmittance also decreases.

Chemistry

[0009] The color of the glass changes as the concentration of FeO relative to Fe2O3 changes. The color can be varied from yellow to green, blue, and finally to amber. From blue to amber, the color change is due to the formation of iron polysulfides under high redox conditions. The color changes as follows (based on experimental results): Yellow - Low redox (0.12) - High light transmittance (high iron ions) Yellow - Green (0.16) Green - Yellow (0.20) Green (Typical value for green glass: 0.25) Bluish green (0.29) Greenish Blue (0.35) Blue (0.50) Olive Green (0.60) Champagne (0.65) Amber - High redox (0.75) - Low light transmittance (low iron ions)

[0010] To control the balance between ferrous oxide and ferric oxide, batch conditions and the molten atmosphere must be set. In the first case, the concentrations of reducing agents such as carbon or tin oxide and oxidizing agents such as sodium sulfate are adjusted. Regarding the molten conditions, the furnace atmosphere with varying oxygen levels and the flame arrangement during combustion must be adjusted according to the thermal performance and the desired glass hue.

[0011] Sodium sulfate (Na2SO4) is added to the batch as a raw material. It is mainly used as an antifoaming agent in high-temperature refining, to promote material transport, to dissolve free silica on the glass surface, and to reduce solid inclusions.

[0012] On the other hand, sodium sulfate has an oxidizing effect, so a small amount of carbon is usually added to prevent unwanted oxidation and to lower the reaction temperature.

[0013] During the glass manufacturing process, Na2SO4, the main component of sulfur in the glass, is converted to SO3, and the conversion of Fe2O3 to FeO is controlled. However, the SO3 present in the final glass does not affect the visible light transmission ability of the glass. The amount of SO3 dissolved in the glass decreases in the following cases: 1. The amount of sodium sulfate is small (proportionally). 2. High melting property. 3. Long melting time. 4. Furnace environment with greater oxidation effect. 5. The reduction of iron to ferrous iron proceeds further (more Fe 2+ ; less Fe 3+ ), reaching at least 70 - 75% of Fe 2+ .

[0014] Therefore, the amount and effect of SO3 in the glass batch need to be balanced according to the amount of carbon present in the glass batch.

[0015] Furthermore, since less SO3 in the glass batch affects the purification characteristics, i.e., the ability to remove bubbles in the melting furnace, it is common knowledge that the SO3 in the glass batch must be within a certain critical amount.

[0016] The first reducing agent is tin oxide (SnO2) (mentioned in D. Benne et al. in the paper, “The effect of alumina on the Sn 2+ / Sn 4+ redox equilibrium and the incorporation of tin in Na2O / Al2O3 / SiO2melts” Journal of Non - Crystalline Solids. 337, 2004, 232 - 240). Tin in contact with the molten glass diffuses into the glass in an oxidized state and also interacts with other polyvalent elements such as iron and chromium. At high temperatures, tin is in a reduced state Sn 2+ , an oxidized state Sn 4+ , and it is found to be in equilibrium with the dissolved oxygen in the melt. [ka]

[0017] The aforementioned phenomenon relates to tin's ability to transfer two electrons to iron. This reaction occurs initially when tin is heated and reduced during the melting of glass. [ka]

[0018] Subsequently, during the cooling stage, ions Sn 2+ +2e - two ferric Fe 3+ The ions are two ferrous Fe 2+ It is reduced to ions. [ka]

[0019] Part of the equilibrium of the redox ratio is achieved using reducing substances such as carbon. This substance exists as ordinary coal or low-iron graphite and interacts with iron and sulfur. Large amounts of carbon interact with iron, reducing it to form iron sulfide, which can give glass an amber hue. 2+ Shape it into this form.

[0020] Titanium dioxide also functions as a coloring agent, and when used in combination with Fe2O3, it functions as a colorant. The most stable form of titanium in glass is tetravalent (Ti 4+). MD Beals, “Effects of Titanium Dioxide in Glass”, The Glass Industry, September 1963, pp 495-531, discusses the interest shown in titanium dioxide as a component of glass. The effects of using titanium dioxide are commented on as significantly increasing the refractive index of TiO2, increasing the absorption of ultraviolet light, and decreasing viscosity and surface tension. Data on the use of titanium dioxide in enamels indicates that it enhances the chemical durability of TiO2 and acts as a flux. Transparent glass containing titanium dioxide can be found in all common glass-forming systems (borate, silicate, phosphate). The various areas of glass formation in titanium dioxide-containing systems are not grouped together in one place because the discussion is based more on the properties of the titanium dioxide-containing glass than on its composition, rather than on its applications.

[0021] There is literature on colored glass compositions that have the property of absorbing infrared and ultraviolet rays. WA Weyl's book “Coloured Glasses, Society of Glass Technology”, reprinted 1992, describes various theories on glass color related to current views on the structure and composition of glass. In this book, the use of chromium and its compounds in coloring glass is mentioned. In the glass industry, chromium is added to the raw materials to obtain an emerald green color; this is Cr 3+ It is a typical color. Chromium is Cr 6+ or CrO4 2- When it exists as such, it becomes a pale yellow, Cr 2+ When it exists as such, it yields an emerald green color.

[0022] In his book, “Colour Generation and Control in Glass, Glass Science and Technology”, Elsevier Science Publishing Co., Amsterdam, 1977, CR. Bamford describes the principles, methods, and applications of coloring glass. These include the color of incident light, the interaction between the glass and the light, and the interaction between transmitted light and the observer's eye. The procedure requires data on the glass's thickness and spectral transmittance at the relevant viewing angle.

[0023] The paper by Gordon F. Brewster et al., “The color of iron-containing glasses of varying composition”, Journal of the Society of Glass Technology, New York, USA, April 1950, pp. 332-406, evaluates the color changes due to systematic compositional variations in iron-containing silica glass and silica-free glass based on visual color, spectral transmittance, and chromaticity.

[0024] Furthermore, other papers have also discussed the importance of the equilibrium between ferrous and ferric oxides in glass, such as NE Densem; “The equilibrium between ferrous and ferric oxides in glasses”; Journal of the Society of Glass Technology, Glasgow, England, May 1937, pp. 374-389; and JC Hostetter and HS Roberts, “Note on the dissociation of ferric oxide dissolved in glass and its relation to the color of iron-bearing glasses”; Journal of the American Ceramic Society, USA, September 1921, pp. 927-938.

[0025] U.S. Patent No. 4,792,536 (Pecoraro et al.) relates to a blue glass composition that enhances the iron state of iron oxide using reducing conditions, preferably having an opaque blue-tinted glass, a composition having at least 0.45 wt% iron represented as Fe2O3, at least 35% of the iron state represented as FeO, and at least 70% visible light transmittance. This patent also discloses low-iron and high-iron, high-redox soda-lime silica glass compositions produced by multi-stage melting and vacuum-assisted refining operations, or those produced by conventional float glass systems.

[0026] U.S. Patent No. 6,313,053 (Shelestak) discloses the use of iron, cobalt, and optionally chromium colorants in proportions present in about 0.40 to 1.0 percent Fe2O3, about 4 to 40 ppm CoO, and optionally about 100 ppm Cr2O30, with a redness greater than 0.35 to about 0.60 and a light transmittance of at least 55% at a thickness of about 0.154 inches. Other components present in the composition include up to about 0.3 wt% SO3, about 0.5% Nd2O30, about 0.5% ZnO0, about 3 ppm Se0, about 0.1 wt% MnO20, about 1.0 wt% CeO20, about 0.5 wt% TiO20, and about 2.0 wt% SnO20. This patent also discloses currently available methods for manufacturing glass, particularly those that maintain the oxidation-reduction ratio of the glass within the range of 0.02 to 0.06.

[0027] U.S. Patent Application No. 2007 / 0213197A1 (Boulos et al.), incorporated herein by reference, discloses that a colored glass composition is proposed in a colorant composition comprising 0.4–0.6 wt% Fe2O3, 0.18–0.28 wt% FeO, 0.05–0.3 wt% MnO2, and 0–8 ppm CoO to adjust the aqua blue color, used in a thickness of 4.0 mm with a dominant wavelength of 489.2 nm ± 1.2 nm, an oxidation-reduction ratio in the range of approximately 0.40–0.58, an excitation purity of 7% ± 1%, and an infrared transmittance in the range of 16%–29%.

[0028] U.S. Patent No. 5,030,594 (Heithoff) discloses that a clear glass with a light transmittance of 87% or more, produced using a multi-stage melting and vacuum-assisted refining system, can be obtained with a blue-rimmed tint. The composition of this glass uses very small amounts of iron oxide and at least 0.4% iron, sodium sulfate is limited to 0.05 percent expressed as SO3, and the batch material does not contain limestone or dolomite, but instead uses aragonite.

[0029] U.S. Patent No. 6,218,323 (Bretschneider et al.) proposes a neutral colored glass having 0.1 to 1 ppm of CoO, ≤0.03 wt% of Fe2O3 and ≤0.0% of a colorant portion, incorporated herein by reference. A base composition of 4 FeO / Fe2O3, preferably 0.3, and soda-lime-silica is used, and this glass has a light transmittance of at least 89% (illuminance D65 according to DIN 67 507) at a reference thickness of 4 mm.

[0030] U.S. Patent No. 6,962,887 (Heithoff) describes a clear glass with a blue rim, manufactured using an oxygen-fueled, non-vacuum float glass system, which is incorporated herein by reference. The patent is characterized in that the rim contains 0-0.2 wt% Fe2O3, 0-0.1 wt% NdO, and 0-0.3 wt% CuO, with 0-5 ppm CoO, 0-0.1 wt% Nd2O3, 0-0.3 wt% CuO, less than 0.11 wt% SO3 retaining sulfur, a redox ratio in the range of 0.3-0.6, and an oxidizing agent comprising at least one of sodium nitrate and cerium oxide. The resulting glass has a thickness equivalent to 5.5 mm when viewed from the edge and a dominant wavelength in the range of 485 nm to 505 nm.

[0031] U.S. Patent No. 6,548,434 (Nagashima) proposes a light-colored, high-transmittance glass containing less than 0.06% by weight of Fe2O3, 0.5 to 5 ppm of CoO, and 0 to 0.45% of CeO2 as coloring components (incorporated herein by reference); where the ratio of FeO (Fe2O3) on a basis of total iron is less than 40%, and this glass has a dominant wavelength of 470 to 495 nm for a light blue hue at a thickness of 10 mm, and a dominant wavelength of 560 to 585 nm for a neutral gray or bronze hue. This glass also contains 0.05 to 0.25% SO3 and, to avoid the formation of NiS, contains 0.001 to 1 wt% of at least one heavy element oxide from the group Y, La, Zr, Hf, Nb, Ta, W, Zn, Ga, Gc, and Sn.

[0032] U.S. Patent No. 8,361,915 (Cid-Aguilar et al.), incorporated herein by reference, proposes a clear glass containing, by weight percent, about 0.005 to about 0.08% ferric oxide, 0.00002 to about 0.0004% Se, 0 to about 0.003 to about 0.0010% CoO, 0.01% wt. CuO, about 0.6 to about 0.6% CeO2, about 0.02 to about 1.0% TiO2, and about 0 to about 2% NaNO3, wherein the clear glass has a visible light transmittance of at least 87%, an ultraviolet transmittance of 85% or less, and a direct solar transmittance of 90% or less.

[0033] U.S. Patent No. 8,962,503 (Nagai et al.), incorporated herein by reference, proposes a colored glass plate in which the total sulfur content, calculated as SO3, is 0.025–0.065%, and the total tin content, calculated as Fe2O3 and SnO2, is 0.001–5.0%, thereby having a blue or green color when transmitted light.

[0034] U.S. Patent No. 10,011,521B2 (Nagai et al.) describes a colored glass using Fe2O3 as the main coloring agent, which provides blue or green transmitted light at a rate of 0.001 to 5.0% when calculated as total iron Fe2O3. The main use of SO3 is as a fining agent for molten glass, with a total sulfur content of less than 0.005 to 0.025% for a 4mm thickness, and the use of SnO2 in this glass is as a buffer for the redox reaction between iron and sulfur, with a tin content of 0.001 to 5.0%. The glass in this patent is a 4mm thick glass as defined in JIS R3106 (1998), with a solar transmittance T e Up to 65%, light transmittance T v (At illuminance A, with a 2° field of view) the maximum is 60%. [Overview of the project]

[0035] It would be advantageous to provide soda-lime silica glass having high visible light transmittance. Furthermore, it would be advantageous to provide a method for manufacturing low-iron soda-lime silica glass that can be used regardless of the type of heating system or furnace used to melt the glass batch material, thereby eliminating the associated limitations.

[0036] Summary of the Invention According to the present invention, for a thickness of 5.66 mm, a purity of 1% or less (Pe) and a high visible light transmittance of at least 89% (L) at a dominant wavelength (DW) of approximately 490-505 nanometers are achieved. tC A glass or glass plate is provided having a soda-lime silica glass composition having ). The glass composition contains a critical amount of 0.02 to 0.06 wt% total iron oxide (Fe2O3); 0.006 to 0.02 wt% FeO (ferrous), about 0.30 to 0.55 redox (FeO / Fe2O3); about 0.3 to 10 ppm Cr2O3; about 50 to 500 ppm TiO2; about 10 to 500 ppm SnO2; and about 0.10 to 0.25 wt% SO3.

[0037] The main objective of the present invention is to provide a transparent glass composition having high visible light transmittance.

[0038] Another objective of the present invention is to provide low-cost clear glass. This can be achieved by using low-iron raw materials such as low-iron dolomite and a mixture of clear glass and low-iron cullet to achieve an appropriate balance in the concentrations of colorants such as Cr2O3, TiO2, and Fe2O3. Alternatively, by partially substituting low-iron raw materials other than low-iron dolomite with conventional raw materials, the concentrations of colorants such as Cr2O3, TiO2, and Fe2O3 can be achieved by using conventional sand containing these oxides as impurities.

[0039] Further non-limiting embodiments or aspects are provided and described in the following sections.

[0040] Clause 1: A transparent glass having a soda-lime silica glass composition, containing 0.02 to 0.06 wt% total iron oxide (Fe2O3), 0.006 to 0.02 wt% ferrous iron (FeO), approximately 0.30 to 0.55 wt% redox (FeO / Fe2O3), approximately 0.3 to 10 ppm Cr2O3, approximately 50 to 500 ppm TiO2, approximately 10 to 500 ppm SnO2, and approximately 0.10 to 0.25 wt% SO3.

[0041] Clause 2: The clear glass according to Clause 1, wherein the low iron oxide content is achieved by partially substituting the normal raw material with a low iron raw material and / or by completely substituting the normal dolomite with a low iron dolomite, the low iron dolomite having a maximum iron oxide concentration of 0.020 wt.%.

[0042] Clause 3: Visible light transmittance of at least 89% (L tC A transparent glass according to clause 1 or 2, having a dominant wavelength (DW) of approximately 490 to 505 nanometers and a purity of 1% or less (Pe), characterized in that the glass has a thickness in the range of 2 to 19 mm.

[0043] Clause 4: When the transparent glass has a controlled thickness of approximately 5.6 mm to 25 mm, it must have a visible light transmittance of at least 89% (L tC ), transparent glass as described in any one of clauses 1 to 3, having a dominant wavelength (DW) of approximately 490 to 505 nanometers and a purity (Pe) not exceeding 1%.

[0044] Clause 5: Transparent glass according to any one of Clauses 1 to 4, wherein the glass has a thickness of 1.0 mm to 25 mm, preferably 2.0 mm to 19 mm, more preferably 2.0 mm to 10 mm, and most preferably 2.0 mm to 6.0 mm.

[0045] Clause 6: Transparent glass as described in any of Clauses 1-5, where the glass is plate glass.

[0046] Clause 7: A method for producing clear glass using a conventional float non-vacuum glass system, comprising the steps of: providing a glass batch, the glass batch containing low iron dolomite in the range of 5 to 20 wt%, the low iron dolomite constituting a maximum total iron content of 0.030 wt%, preferably 0.025 wt%, more preferably 0.022 wt%, expressed as Fe2O3; melting the glass batch to provide molten glass; flowing the molten glass onto a molten tin bath; moving the glass on the surface of the molten tin bath while controllingly cooling the molten glass, applying force to the glass melt to provide glass of a desired thickness and width; and removing the glass from the molten tin bath.

[0047] Clause 8: The method according to Clause 7, wherein the melting process is carried out in a furnace having combustion, the furnace being an air-fueled or oxygen-fueled furnace, and the combustion controls the oxidation-reduction (FeO / Fe2O3) in the glass to about 0.30-0.55 wt%.

[0048] Clause 9: The method according to Clause 7 or 8, further comprising mixing low-iron dolomite with cullet, sand, soda ash, limestone, salt cake, coal, graphite, or a combination thereof. Clause 10: The method according to any one of Clauses 7 to 9, wherein the low-iron dolomite further comprises calcium oxide and magnesium oxide.

[0049] Clause 11: The method according to any one of Clauses 7 to 10, wherein the oxidation-reduction is controlled by a reducing agent such as carbon or tin oxide, and an oxidizing agent such as sodium sulfate.

[0050] Clause 12: Transparent glass, as follows: [Table 12] Includes, At least 89% visible light transmittance (L tC), a transparent glass sheet having a dominant wavelength (DW) of approximately 490 to 505 nanometers and a purity of 1% or less (Pe), wherein the glass has a thickness of 2 to 19 mm, according to any one of the methods of Clauses 7 to 11.

[0051] Clause 13: The method according to any of Clauses 7 to 12, wherein the low-iron dolomite contains a maximum of 0.020 wt% total iron expressed as Fe2O3.

[0052] Clause 14: The method according to any one of Clauses 7 to 13, further comprising adjusting the oxygen or air in the furnace to produce glass having an oxidation-reduction ratio of 0.30 to 0.55 (FeO / Fe2O3).

[0053] Clause 15: The method according to any one of Clauses 7 to 14, wherein the low iron dolomite further comprises 5 to 15 wt% CaO and 2 to 10 wt% MgO.

[0054] Clause 16: The method of manufacturing glass, wherein the method is changed from one glass batch portion to the other glass bath portion, by changing the weight percentage of tin and / or tin-containing compounds to change the weight percentage of total iron within a specified range for the glass batch portion to be changed.

[0055] Clause 17: The method according to any one of Clauses 7 to 16, wherein the glass batch further comprises low-iron raw materials selected from the group including low-iron sand, low-iron calcite, low-iron cullet, low-iron graphite, and combinations thereof.

[0056] Clause 18: The method according to any one of Clauses 7 to 17, further comprising using carbon and tin oxide as reducing agents.

[0057] Clause 19: The method according to any one of Clauses 7 to 18, further comprising using sodium sulfate as an oxidizing agent.

[0058] Clause 20: A method for forming clear glass using a conventional float non-vacuum glass system, comprising: providing a glass batch; melting glass to provide a pool of molten glass; flowing the molten glass onto a molten tin bath; moving the molten glass on the surface of the molten tin bath while controllingly cooling the glass to apply force to the glass to provide glass of a desired thickness and width; and removing the glass from the molten tin bath, wherein the glass is formed using raw materials alone or in combination of the following amounts. [Table 20]

[0059] Clause 21: The method according to Clause 20, wherein the composition comprises sand with a maximum Fe2O3 content of 0.010%, calcite with a maximum Fe2O3 content of 0.010%, low iron graphite with a maximum Fe2O3 content of 0.010%, or cullet with a maximum Fe2O3 content of 0.010%.

[0060] Clause 22: The method according to either Clause 20 or 21, wherein the glass contains SiO2 in the range of 68-75 wt%, preferably 70-74 wt%, more preferably 71-74 wt%, and most preferably 72-74 wt%.

[0061] Clause 23: The method according to any of Clauses 20 to 22, wherein the glass has a redox (FeO / Fe2O3) ratio in the range of 0.25 to 0.55, preferably 0.27 to 0.48, more preferably 0.30 to 0.47, and most preferably 0.35 to 0.46.

[0062] Clause 24: The method according to any one of Clauses 20 to 23, wherein the glass has Na2O in the range of 10-15 wt%, preferably 12-14 wt%, more preferably 13-14 wt%, and most preferably 13.8-14.0 wt%.

[0063] Clause 25: The method according to any one of Clauses 20 to 24, wherein the glass contains SO3 in the range of 0.1 to 0.3 wt%, preferably 0.15 to 0.25 wt%, more preferably 0.17 to 0.22 wt%, and most preferably 0.18 to 0.21 wt%.

[0064] Clause 26: The glass has a color a in the range of 1.0 to -1.0, preferably 0.0 to -0.8, more preferably 0.0 to -0.5, and most preferably 0.0 to -0.4. * , and b in the range of 1 to -1, preferably 0.5 to -0.5, more preferably 0.3 to -0.2, and most preferably 0.2 to -0.1 * A clear glass having any of the characteristics described in clauses 1 to 6.

[0065] Clause 27: The glass has a color a in the range of 1.0 to -1.0, preferably 0.0 to -0.8, more preferably 0.0 to -0.5, and most preferably 0.0 to -0.4. * and b in the range of 1 to -1, preferably 0.5 to -0.5, more preferably 0.3 to -0.2, and most preferably 0.2 to -0.1 * A method according to any one of clauses 20 to 25, having the same method.

[0066] Clause 28. Glass including the following: [Table 28]

[0067] Clause 29: Glass including the following: [Table 29]

[0068] Clause 30: Glass including the following: [Table 30]

[0069] Clause 31: Glass including the following: [Table 31]

[0070] Clause 32: The glass according to any one of Clauses 28 to 31, further comprising 50 to 500 ppm of TiO2, preferably 75 to 450 ppm of TiO2, more preferably 90 to 400 ppm, and most preferably 100 to 390 ppm of TiO2.

[0071] Clause 33: The glass according to any one of Clauses 28 to 32, further comprising 0.1 to 7 ppm of Cr2O3, preferably 0.3 to 6 ppm of Cr2O3, more preferably 0.5 to 5.7 ppm of Cr2O3, and most preferably 0.6 to 5.6 ppm of Cr2O3.

[0072] Clause 34: Glass according to any of Clauses 28 to 33, further comprising 25 to 500 ppm of SnO2, preferably 35 to 450 ppm of SnO2, more preferably 40 to 420 ppm of SnO2, and most preferably 47 to 414 ppm of SnO2.

[0073] Clause 35: Glass conforming to any of Clauses 28-34, further comprising the following features: light transmittance (L) of at least 85%, preferably at least 88%, more preferably at least 89%, and most preferably at least 89.9%. tC ); UV transmittance of less than 90%, preferably less than 88%, more preferably less than 86%, and most preferably 85.4% (T uv ); Infrared transmittance (T ir ) is less than 90%, preferably less than 88%, more preferably less than 86%, most preferably less than 85.2%; total solar energy transmittance (TSET) is up to 92%, preferably up to 90%, more preferably up to 89%, most preferably up to 88.7%; lightness value (L * ) is 90-99; preferably 92-98; more preferably 95-97; most preferably 96-96.3_;a * The color channels are in the range of 1 to -2, preferably 0.5 to -1.5, more preferably 0 to -1, and most preferably -0.4 to -1.0; b *The color channels are 1 to -1, preferably 0.5 to -0.5, more preferably 0.3 to -0.2, most preferably 0.2 to -0.1; the dominant wavelength is 470 to 525 nm, preferably 475 to 520 nm, more preferably 480 to 515 nm, most preferably 490 to 505 nm; and the purity (Pe) is 2% or less, preferably 1% or less, more preferably 0.6% or less, most preferably 0.5% or less.

[0074] Clause 36: A method for forming clear glass, comprising a step of mixing raw materials, wherein the raw materials include cullet, sand, soda ash, salt cake, limestone and dolomite, and the dolomite includes: [Table 36] A method for forming transparent glass, comprising the steps of: melting raw materials to form molten glass; pouring the molten glass onto a molten tin bath; applying force to the molten glass by moving it on the surface of the molten tin bath while controllingly cooling it, thereby forming glass of a desired thickness and width; and removing the glass from the molten bath.

[0075] Clause 37: The method described in Clause 36, provided that the raw materials are present in the following quantities: [Table 37]

[0076] Clause 38: Sand is provided in any way described in Clause 36 or 37, including: [Table 38]

[0077] Clause 39: The salt cake is made in any way described in Clauses 36 to 38, including: [Table 39]

[0078] Clause 40: The method used by Carret in any of Clauses 36 to 38, including: [Table 40]

[0079] Clause 41: Limestone is obtained in any of the manner described in Clauses 36 to 40, including: [Table 41]

[0080] Clause 42: The method of soda ash as described in any of Clauses 36 to 41, including: [Table 42]

[0081] Clause 43: The method according to any one of Clauses 36 to 42, wherein the raw materials further include coal or graphite.

[0082] Clause 44: The method according to Clause 43, wherein the coal or graphite is in the range of 0.01 to 0.3 wt.%; preferably 0.02 to 0.2 wt.%; more preferably 0.03 to 0.1 wt.%; most preferably 0.04 to 0.08 wt.%.

[0083] Clause 44: The method described in Clause 43 or 44, including the following, for coal or graphite: [Table 44] [Brief explanation of the drawing]

[0084] Simple description of the drawing [Figure 1] Figures 1A and 1B are horizontal cross-sectional views of a glass melting furnace that can be used in carrying out the present invention, where Figure 1A is the melting section of the furnace and Figure 1B is the refining and homogenization section of the furnace.

[0085] [Figure 2] Figure 2 is a vertical cross-sectional view of the molten area shown in Figure 1A.

[0086] [Figure 3] Figure 3 is an elevation view showing a partial cross-section of a glass melting and refining apparatus that can be used in carrying out the present invention.

[0087] [Figure 4] Figure 4 is a fragmentary side view of a glass ribbon supported on a molten tin bath. [Modes for carrying out the invention]

[0088] Description of the invention Where used in the following discussion, unless otherwise specified, all numerical values ​​representing dimensions, etc., used herein and in the claims shall be understood to be modified in all cases by the term “approximately”. Accordingly, unless otherwise specified, the numerical values ​​described herein and in the claims may vary depending on the desired characteristics to be obtained by the present invention. Not to the effect of limiting the application of the doctrine of equivalents to the claims, each numerical parameter should be interpreted by applying ordinary rounding techniques, at least in light of the reported number of significant figures. Furthermore, all ranges disclosed herein should be understood to include the start and end values ​​of the range and to encompass any and all subranges contained therein. For example, the range “1 to 10” should be considered to include all ranges between the minimum value “1” and the maximum value “10”, i.e., all ranges starting with a minimum value of 1 or more and ending with a maximum value of 10 or less, e.g., “5.5 to 10”. Furthermore, all documents referred to herein (such as issued patents and patent applications) shall be considered to be “incorporated by reference” in their entirety.

[0089] Unless otherwise specified, all references to compositional amounts are in "weight percent" based on the total weight of the final glass composition. The "total iron" content of the glass compositions disclosed herein is expressed in units of Fe2O3, according to standard analytical methods, regardless of the form in which it actually exists. Similarly, the amount of iron in the ferrous state is reported as FeO, even though it may not actually be present in the glass as FeO. The terms "redox," "redox ratio," or "iron redox ratio" mean the amount of iron in the ferrous state (expressed as FeO) divided by the amount of total iron (expressed as Fe2O3). As used herein, soda-lime silica glass with a total iron content (expressed as Fe2O3) in the range of 0 to 0.06 wt% is considered low-iron soda-lime silica glass. Generally, but not limiting to the present invention, high-iron soda lime silica glass has a total iron content in the range of 0.10 wt% to 2.0 wt% and greater; 0.10 wt% to 1.5 wt% and greater; 0.10 wt% to 2.0 wt%; and 0.10 wt% to 0.80 wt%.

[0090] As can now be understood, the present invention is directed toward the production of low-iron, high-redox soda-lime silica glass and is not limited to optical properties, such as ultraviolet-visible and IR transmittance and absorption, as well as the color and physical properties of the glass, such as the thickness of the glass. When defining non-limiting embodiments of the glass of the present invention, specific ranges or values ​​of ultraviolet, visible and infrared transmittance and absorption, as well as the color and physical properties of the glass, such as the thickness of the glass, may be referred to in order to identify specific glasses of the present invention and / or glasses produced by the implementation of the present invention. Presented below are glass batch materials and / or common additives added to molten glass to alter the optical and physical properties of the glass of the present invention, such as color additives.

[0091] The "sulfur" content of the glass compositions disclosed herein is expressed in terms of SO3, regardless of the actual form it exists in, according to standard analytical methods.

[0092] As used herein, the "visible transmittance" and "dominant wavelength" values ​​are determined using conventional CIE illuminance C and an observer angle of 2 degrees. Those skilled in the art will understand that even if the actual thickness of the measured glass sample differs from a standard thickness, properties such as visible transmittance and dominant wavelength can be calculated using an equivalent standard thickness, for example, 5.5 millimeters ("mm").

[0093] As should be understood, the present invention is not limited to the coloring additives described above, and any coloring additive for soda-lime silica glass known in the art may be used in carrying out the present invention, such as, but not limited to, coloring additives selected from the group including CoO, Se, NiO, Cl, V2O5, CeO2, Cr2O3, TiO2, Er2O3, MnO2, La2O3 and combinations thereof.

[0094] As can now be understood, the present invention is not limited to the process and / or apparatus for manufacturing the glass of the present invention, but any glass manufacturing process and / or apparatus known in the art can be used in carrying out the present invention.

[0095] Referring to Figures 1 and 2 as necessary, a conventional continuous feed, cross-tank firing, glass melting and non-vacuum refining furnace 20 is shown, having a housing formed by a bottom 22 containing refractory material, a roof 24, and side walls 26. Glass batch material 28 is introduced in any convenient or conventional way through an inlet opening 30 of an extension 32 of the furnace 20 known as a filled doghouse to form a floating blanket 34 on the surface 36 of the molten glass 38. The overall progress of the glass, as shown in Figures 1A and 1B, is from left to right in the figure, toward the inlet end of a glass forming chamber 40 of the type used in the art to make float plate glass.

[0096] Flames (not shown) for melting the batch material 28 and heating the molten glass 38 are emitted from burner ports 42 spaced along the side wall 26 (see Figure 2) and directed onto and beyond the surface 36 of the molten glass 38. During the first half of the heating cycle, flames are emitted from each nozzle 43 (see Figure 2) of the ports on one side of the tank 20 as the furnace exhaust moves through the ports on the opposite side of the furnace. In the second half of the heating cycle, the functions of the ports are reversed, with the exhaust port becoming the firing port and the firing port becoming the exhaust port. Firing cycles of furnaces of the type shown in Figures 1 and 2 are well known in the art. As will be understood by those skilled in the art, the present invention intends to use a mixture of air and fuel gas, or a mixture of oxygen and fuel gas, to generate flames for heating the batch material and molten glass. For a discussion of the use of oxygen and fuel gas in the type of reactor shown in Figure 1, refer to U.S. Patents 4,604,123, 6,962,887, 7,691,763, and 8,420,928, which are incorporated herein by reference.

[0097] As the glass batch material 28 moves downstream from the batch supply end or doghouse end wall 46, it is melted in the melting section 48 of the furnace 20, and the molten glass 38 moves through the waist 54 of the refining section 56 of the furnace 20. In the refining section 56, bubbles in the molten glass 38 are removed, and the molten glass 38 is mixed or homogenized as it passes through the refining section 56. The molten glass 38 is sent from the refining section 56 to a pool of molten metal (not shown) contained in the glass forming chamber 40 by any convenient or conventional method. As the sent molten glass 38 moves within the glass forming chamber 40 on the pool of molten metal (not shown), the molten glass is sized and cooled. A dimensionally stable glass ribbon (not shown) is moved from the glass forming chamber 40 to the annealing rare (not shown). Glass manufacturing apparatuses of the type shown in Figures 1 and 2, and the type described above, are well known in the art.

[0098] Figure 3 shows a continuous-feed glass melting and vacuum refining apparatus 78 for melting glass batch material and refining molten glass. Preferably, the pulverized batch material 80 is fed into a cavity 82 of a liquefaction vessel, such as a rotating drum 84. A layer 86 of the batch material 80 is held against the inner wall of the vessel 84 with the help of the rotation of the drum and acts as an insulating lining. When the batch material 80 on the surface of the lining 84 is exposed to the heat in the cavity 82, it forms a liquefaction layer 88 which flows out into the melting vessel 94 through a central drain opening 92 at the bottom of the vessel 84, completing the dissolution of any unmelted particles in the liquefaction material coming from the vessel 84.

[0099] Valve 96 controls the flow of material from the melting vessel 94 into a generally cylindrical, vertically positioned vessel 98, which has an internal ceramic refractory lining (not shown) covered by a gas-sealed, water-cooled casing 100. The molten flow of refined glass 102 can fall freely from the bottom of the refined vessel 98 and be passed on to subsequent stages of the glass manufacturing process. For a detailed discussion of the operation of the apparatus 78 shown in Figure 3, refer to U.S. Patent No. 4,792,536.

[0100] The glass of the present invention can be manufactured using any known glass manufacturing process. For example, without limiting the present invention, the low-iron, high-oxidation-reduction glass of the present invention can be manufactured by a multi-stage melting and vacuum-assisted purification operation shown in Figure 3. The purification step of this known process is carried out under vacuum to reduce the concentration of dissolved gases and volatile gas components, particularly sulfur-containing components. As will be understood by those skilled in the art, the combination of sulfur and iron in glass can lead to the formation of iron sulfide (conventionally also called iron sulfide or polysulfide), resulting in amber coloration of the glass at high oxidation-reduction ratios, e.g., 0.4 or higher, particularly at iron oxidation-reduction ratios of 0.5 or higher; therefore, it can be advantageous to remove sulfur-containing components from certain float glass compositions. Iron sulfide can form throughout the bulk glass or in streaks or layers of glass sheets. In this specification, the term “bulk glass” means the portion of a glass piece, such as a glass plate, that has not been chemically altered during the glass formation process. For glass sheets thicker than 2 millimeters ("mm") manufactured by the float glass process, the bulk glass does not include the outer region of the glass adjacent to the glass surface, for example, the outer 25 microns (measured from the glass surface). The removal of gaseous sulfur components in the vacuum purification step of this known process helps prevent the formation of ferric sulfide in the glass and thus prevents amber discoloration.

[0101] As described above and shown in Figures 1 and 2, conventional float glass systems typically include a furnace or melter into which the glass material is placed for melting. In one embodiment of the present invention, the melting furnace may be an oxygen-fueled furnace that mixes fuel with oxygen to supply heat for melting the batch material. In another embodiment of the present invention, the melting furnace may be a conventional air-fueled melting furnace in which air is mixed with the combustion fuel to supply heat for melting the batch material. In yet another embodiment of the present invention, the melting furnace may be a hybrid melting furnace in which an oxygen lance is added to a conventional pneumatic melting furnace to supply oxygen to air heated before combustion.

[0102] One difference between glass made from batch material melted in an oxygen-fueled furnace and glass made from batch material melted in a conventional air-fueled melting furnace is that glass made from batch material melted in an oxygen-fueled furnace typically has a moisture content in the range of 425–600 ppm, while glass made from batch material melted in a conventional air-fueled melting furnace typically has a moisture content in the range of 200–400 ppm, and glass made from 100% cullet melted in an oxygen-fueled furnace generally has a moisture content of about 700 ppm. In a preferred embodiment of the present invention, the glass batch material is melted in an oxygen-fueled furnace or a conventional air-fueled melting machine. In the following description of the present invention, the present invention is carried out using an oxygen-fueled furnace, but the present invention is not limited thereto, and it is possible to carry out the present invention using any type of glass melting apparatus.

[0103] In the implementation of the present invention, typical batch materials for producing soda-lime silica glass are introduced into a melting furnace, furnace 20 shown in Figure 1, and furnace 84 shown in Figure 3. Typical batch materials for soda-lime silica glass compositions include sand, soda ash, limestone, alumina, and dolomite. In one non-limiting embodiment of the present invention, low-iron dolomite is used as the batch material. As will be understood by those skilled in the art, conventional soda-lime silica batch materials also include melting and refining aids such as salt cake (sodium sulfate). When incorporated into the glass batch, salt cake can also act as an oxidizing agent. If salt cake is completely removed from the batch material, in addition to an increase in melting difficulty, the oxidation-reduction ratio of the glass rises to a degree that can form polysulfides in the bulk glass, resulting in an amber tint to the bulk glass. To control the oxidation-reduction ratio of the glass, a non-sulfur-containing oxidizing agent can be added to the batch material instead of salt cake to oxidize Fe++ to Fe+++ and reduce the oxidation-reduction ratio. A non-limiting example of such a material is sodium nitrate (NaNO3). Sodium nitrate can prevent the oxidation-reduction ratio of the glass from rising to the point where the formation of bulk polysulfides produces an undesirable amber tint in the bulk glass, although sodium nitrate is involved in the glass manufacturing process.x This can cause emissions of NO. x To meet government regulations regarding emissions, the gases from the melting furnace can be treated using conventional methods before being released into the atmosphere.

[0104] Non-limiting embodiments of the present invention are carried out to produce the transparent glass of the present invention, which is formed by a float glass process, comprising the following formulations based on weight percentages with respect to the total weight of the glass, these percentages of which are obtained using X-ray fluorescence analysis. Weight ratio (%) SiO268~75 Al2O30~5 CaO 5-15 MgO 2-10 Na2O 10~18 K2O 0-5

[0105] In one non-limiting embodiment of the present invention, the total iron oxide (Fe2O3) is in the range of 0.02 to 0.06 wt%, ferrous iron (FeO) is 0.006 to 0.02 wt%, and the redox (FeO / Fe2O3) is about 0.30 to 0.55 wt%; Cr2O3 is about 0.3 to 10 ppm, TiO2 is about 50 to 500 ppm; and the proportion of the reducing agent SnO2 is about 10 to 500 ppm, with a critical amount of the oxidizing agent SO3 being about 0.10 to 0.25 wt.%. Low iron oxide content is achieved by partially substituting the normal raw material with a low iron raw material, and when the normal dolomite is completely replaced with low iron dolomite, the maximum content is 0.020 wt.% Fe2O3.

[0106] In one non-limiting embodiment of the present invention, the low iron dolomite in a batch in the range of 5 to 20 wt% contains 5 to 15 wt% CaO and 2 to 10 wt% MgO. The low iron dolomite contains about 0.020% or less Fe2O3.

[0107] In one non-limiting embodiment, the transparent glass has a high visible light transmittance of at least 89 (L tCIt has a dominant wavelength (DW) of approximately 490-505 nanometers and a purity (Pe) of no more than 1% for a controlled thickness of 5.66 mm.

[0108] Transparent glass with a low iron content has a high visible light transmittance and, due to its low iron content, can make objects seen through the glass appear more beautiful. Furthermore, when used outdoors, it can create a brighter illuminated space, making it of great importance not only in the construction industry but also in the automotive industry and various applications.

[0109] To achieve the described properties, the present invention provides an appropriate balance between ferrous oxide, ferric oxide, and chromium oxide, titanium oxide, and tin oxide and ordinary coal or low-iron graphite, and furthermore, partially or completely replaces ordinary raw materials with low-iron raw materials, such as low-iron sand with a maximum content of 0.010% Fe2O3, low-iron dolomite with a maximum content of 0.020 wt% Fe2O3, low-iron calcite with a maximum content of 0.010% Fe2O3, low-iron cullet with a maximum content of 0.010% Fe2O3, and low-iron graphite with a maximum content of 0.010% Fe2O3.

[0110] Desired properties can be obtained by appropriately balancing the ratio of low-iron raw materials and clear cullet, but this may increase the formulation cost. Alternatively, the desired properties can be obtained by using low-iron raw materials and regular dolomite. In this case, the ratio of clear to low-iron cullet needs to be adjusted, which may increase the cost of the formulation.

[0111] Another variable for realizing the glass proposed in this invention is the oxidation-reduction of iron in the glass, using carbon and tin oxide as reducing agents, and sodium sulfate as an oxidizing and refining agent. Chromium oxide and titanium oxide are permitted as coloring agents.

[0112] According to the present invention, the above performance characteristics are measured as follows: Light transmittance (L tCThe color of the glass is measured using a CIE 2° observer in the wavelength range of 380–770 nanometers with the CIE standard light source "C". The color of the glass is measured using the CIE standard light source "D65" with a 10° observer in terms of dominant wavelength (DW) and excitation purity (Pe), following the procedure established in ASTM E 308-2001. Total solar ultraviolet transmittance (T uv ) is 300-400 nanometers, total solar infrared transmittance (T ir ) is 720-2000 nanometers, total solar energy transmittance (T SET ) is measured in the wavelength range of 300 to 2000 nanometers. uv , T ir , T SET The transmittance data was calculated using direct solar radiation data from the Parry Moon air mass 2.0 and integrated using the trapezoidal rule, as is well known in this industry.

[0113] Also, the color variable L in CIELAB 1976 * a * , b * It is calculated using tristimulus values.

[0114] The glass of the present invention can be melted and refined in a continuous, large-scale commercial glass melting operation, and formed into flat glass sheets of varying thicknesses by a float method, in which the molten glass is supported on a pool of molten metal, usually tin, as it takes on a ribbon shape and cooled in a manner well known in the art.

[0115] The formulations in Table 1 below contain the basic batch components, colorants, and redox agents necessary to produce one ton of glass.

[0116] [Table 1]

[0117] Examples 1-7 use low-iron raw materials in non-limiting formulations of the present invention. 0.6 kg of low-iron graphite and 5.8 kg of salt cake are added to a batch formulation per ton of glass to control oxidation-reduction in the glass, and the iron content is adjusted using a mixture of clear cullet and low-iron cullet.

[0118] The typical raw material compositions in these examples are shown below. [Table 118]

[0119] Examples 8-16 used a mixture containing low-iron raw materials. 0.5 kg of low-iron graphite and 4.3 kg of salt cake were added in batches per ton of glass to control oxidation-reduction in the glass, and the iron content ratio was adjusted using a mixture of clear cullet and low-iron cullet.

[0120] The typical raw material compositions in these examples are shown below. [Table 120]

[0121] Examples 17-21 are formulated using standard raw materials, excluding low-iron dolomite with a maximum content of 0.020 wt% Fe2O3. To control oxidation-reduction in the glass, 0.5 kg of general coal and 6.2 kg of salt cake are added in batches per ton of glass. These formulations show that the cost of the final product is lower because the proportion of Fe2O3 is kept low by substituting low-iron dolomite for general dolomite and general coal for low-iron graphite. In these examples, recycled cullet is used in the formulations.

[0122] The typical raw material compositions in these examples are shown below. [Table 122]

[0123] Examples 22-30 are batch-formulated using conventional raw materials, except that low-iron dolomite with a maximum Fe2O3 content of 0.020 wt%, 0.9 kg of conventional coal, and 6.7 kg of salt cake were added per ton of glass to control oxidation-reduction in the glass. In these examples, low-iron dolomite is used to reduce the proportion of Fe2O3 in the glass, and therefore the amount of conventional limestone is reduced. Recycled cullet is used in the formulation.

[0124] The typical raw material compositions in these examples are shown below: [Table 124]

[0125] The following are examples of soda lime silica compositions shown in Table 2, and according to the proposed method of this invention, the light transmittance (L) at a controlled thickness of approximately 5.66 mm is... tC ), ultraviolet (T uv ), infrared (T ir ), total solar transmittance (T SET The physical properties of ) are reported.

[0126] The following glass compositions were calculated by X-ray fluorescence analysis.

[0127] [Table 2]

[0128] [Table 2]

[0129] [Table 2]

[0130] [Table 2]

[0131] [Table 2]

[0132] Referring to the example in Table 2, the base soda-lime silica glass composition contains chromium and titanium as colorants, and low iron graphite or ordinary coal and tin oxide as redox agents in appropriate balances. In this composition, iron oxide is maintained in the range of 0.02-0.06 wt%, and sulfates are maintained at a critical amount of approximately 0.10-0.25 wt%, so as not to affect the SO3 purification characteristics. The amount of tin oxide and ordinary coal or low iron graphite added varies depending on the initial redox state of the furnace, and the amount of tin oxide required to reach the desired redox state in the glass.

[0133] In Examples 1-7, a mixture of low-iron raw materials, clear cullet (transparent cullet), and low-iron cullet is used to achieve an appropriate balance of iron oxide, chromium oxide, and titanium oxide. In these examples, the amount of SnO2 required to reach the oxidation-reduction state in the glass is reduced due to the oxidation-reduction conditions present in the furnace.

[0134] Examples 8-16 also incorporated low-iron raw materials and were a mixture of clear cullet and low-iron cullet. However, compared to Examples 1-7, the furnace exhibited a low-oxygen state, so a large amount of SnO2 was added to the glass composition.

[0135] Examples 17-21 use ordinary raw materials, excluding low-iron dolomite. In these examples, the appropriate balance of colorants such as iron oxide, chromium oxide, and titanium oxide can be achieved by using ordinary sand in which these oxides are present as impurities. The amount of SnO2 added to achieve the required redox state for the glass varies depending on the redox state in the furnace.

[0136] Examples 22-30 also use conventional raw materials, excluding low-iron dolomite. In these examples, the amount of low-iron dolomite is increased and the amount of conventional limestone is decreased compared to the previous examples. The amount of SnO2 is also varied as needed depending on the oxidation-reduction conditions in the furnace. As with Examples 17-21, the appropriate balance of colorants described can be achieved by using conventional sand.

[0137] Examples 1-21 from Table 2 maintained the TiO2 concentration at approximately 50-500 ppm. Maintaining titanium dioxide within this range improves the light transmittance within the glass, which is one of the main characteristics of the proposed glass. Furthermore, excessive titanium dioxide results in a yellowish tint in the glass.

[0138] Those skilled in the art will understand that if the presence of iron oxide, titanium oxide, or chromium oxide is greater than the ranges mentioned, the light transmittance will decrease to a value lower than the value proposed in this patent.

[0139] The addition and control of these materials imparts a transparent glass according to a non-limiting embodiment of the present invention, which contains about 0.02 to 0.06 wt% total iron oxide (Fe2O3), 0.006 to 0.02 wt% ferrous iron (FeO), about 0.30 to 0.55 wt% redox (FeO / Fe2O3), about 0.3 to 10 ppm Cr2O3, about 50 to 500 ppm TiO2, about 10 to 500 ppm SnO2, and about 0.10 to 0.25 wt% SO3. At a controlled thickness of 5.66 mm, the example glass has a visible light transmittance of at least 89% (L). tC It has a dominant wavelength (DW) of approximately 490 to 505 nanometers and a purity (Pe) not exceeding 1%.

[0140] The compositions disclosed herein are manufactured by a float process in the range of about 1 millimeter to 25 millimeters.

[0141] Once the proposed properties for the transparent glass composition are achieved, other modifications can be applied within the scope of the present invention without departing from those described in the subsequent claims. Accordingly, the specific embodiments described in detail herein are illustrative only and do not limit the scope of the present invention, which should be given the full width of the appended claims and any equivalent thereof. In connection with the present invention, the following is further disclosed. [1] A method for producing clear glass using a conventional float non-vacuum glass system, the method comprising the following: To provide a glass batch containing colorants and components for producing glass having a basic soda-lime silica glass composition; To melt the glass and provide a pool of molten glass; Pouring molten glass onto a molten tin bath; To provide glass of a desired thickness by controllingly cooling the glass and moving the molten glass on the surface of a molten tin bath while applying force to the glass; and To remove the glass from the molten tin bath, Includes, Furthermore, the method for manufacturing transparent glass is changed from one of the glass batches to the other by changing the weight percentage of the coloring agent and changing the weight percentage of iron within a specified range for the glass batch that is to be changed. [2] Conventional float non-vacuum glass systems include a furnace, and combustion in the furnace is caused by ignition of air and / or gas, or by ignition of oxygen / gas, and the glass (FeO / Fe 2 O 3 The method according to [1], which controls the redox in the mixture from approximately 0.30 to 0.55. [3] Combustion in the furnace can be caused by ignition of air / gas or by ignition of oxygen / gas, and by adjusting the oxygen and air during combustion, glass (FeO / Fe 2 O 3 The method according to [2], which can achieve a desired oxidation-reduction in approximately 0.30 to 0.55% by weight. [4] The method according to [2], wherein the source of iron is a low-iron raw material. [5] The method according to [4], wherein the low-iron raw material is low-iron sand, low-iron limestone, low-iron dolomite, low-iron clear cullet, or a combination thereof. [6] Low iron dolomite contains up to 0.020 wt% Fe 2 O 3 The method described in [4], including the method described in [4]. [7] the below described: The process involves mixing raw materials, the raw materials comprising cullet, sand, soda ash, salt cake, limestone, and dolomite, wherein the dolomite contains the following: [Table 1] The process of melting raw materials to form molten glass; Pouring molten glass onto a molten tin bath; controlling the cooling of the molten glass and applying force to it while moving the molten glass on the surface of the molten tin bath to form glass of a desired thickness and width; and Remove the glass from the molten bath. A method for forming transparent glass, including the following. [8] The method according to [7], wherein the raw materials are present in the following amounts. Table 2 [9] The method described in [7], wherein the sand is as follows: Table 3

[10] The salt cake is made according to the method in [7], including the following: Table 4

[11] The method described in [7], including the following: Table 5

[12] The method according to [7], wherein the limestone is as follows: Table 6

[13] The method according to [7], wherein the soda ash comprises the following: Table 7

[14] The method according to [7], further comprising coal or graphite as a raw material.

[15] The method according to

[14] , wherein the coal or graphite is in the range of 0.01 to 0.3 wt%.

[16] The method according to

[14] , wherein the coal or graphite is as follows: Table 8

[17] A glass composition comprising the following: Table 9

[18] Fe 2 O 3 The glass composition according to

[17] , wherein the amount of is 0.021 to 0.053 wt% and the redox is 0.30 to 0.46.

[19] Furthermore, 50-500 ppm TiO 2 The glass composition described in

[17] , comprising:

[20] The glass composition according to

[17] further comprises glass having the glass composition, wherein the glass has a light transmittance of at least 85% (L tc ); Ultraviolet transmittance (Tuv) less than 90%; Infrared transmittance (Tir) less than 90%; Total solar energy transmittance (TSET) at most 92%; Brightness value (L * )90~99;a * Color channels 1 to -2; b * The glass composition comprising color channels 1 to -1; dominant wavelength 470 to 525 nm; and a purity of 2% or less (Pe).

[21] 25-500 ppm SnO 2 The glass composition according to

[17] , further comprising:

[22] The glass composition according to

[17] , wherein the iron oxide content in the glass batch is reduced by a low-iron raw material, and the low-iron raw material comprises low-iron sand, low-iron limestone, low-iron dolomite, low-iron clear cullet, or a combination thereof.

[23] The glass composition according to

[22] , comprising a glass batch containing low iron dolomite in the range of 5 to 20 wt%.

[24] Low iron dolomite contains up to 0.020 wt% Fe 2 O 3 The glass composition according to

[22] , comprising:

Claims

1. A glass composition comprising the following: Table 9 Moreover, the glass composition is a product of a glass batch containing 5-20 wt% low iron dolomite, and said low iron dolomite is Fe ２ O ３ The glass composition having a total iron content of less than 0.1 wt%, a total CaO content of 30 to 35 wt%, and an MgO content of 15 to 25 wt%, as expressed as content.

2. Fe ２ O ３ The amount is 0.021 to 0.053 wt%, and the redox ratio (FeO / Fe ２ O ３ The glass composition according to claim 1, wherein the value expressed as is in the range of 0.30 to 0.

46.

3. The glass composition which is the product of the glass batch according to Claim 1 contains 0.005 to 0.05 wt% TiO ２ The glass composition according to claim 1, further comprising:

4. The glass composition, which is a glass batch formation in Claim 1, has at least 85% light transmittance (L ＴＣ ); less than 90% ultraviolet transmittance (T ｕｖ ); less than 90% infrared transmittance (T ＩＲ ); at most 92% total solar energy transmittance (T ＳＥＴ ); lightness value (L ＊ ) 90 - 99; a ＊ color channel 1 to -2; b ＊ color channel 1 to -1; dominant wavelength 470 - 525 nm; and can be used to produce glass having a purity (Pe) of 2% or less. The glass composition according to Claim 1.

5. The glass composition which is the product of the glass batch according to Claim 1 contains 0.0025 to 0.05 wt% of SnO ２ The glass composition according to claim 1, further comprising:

6. The glass composition according to claim 1, wherein the source of iron in the glass batch in claim 1 further comprises one or more low-iron materials selected from low-iron sand, low-iron limestone, low-iron clear cullet, or a combination thereof.

7. The low iron dolomite in the glass batch according to Claim 1 is Fe ２ O ３ The glass composition according to claim 1, having a total iron content of less than 0.030 wt%, expressed as content.

8. The low iron dolomite in the glass batch according to Claim 1 is Fe ２ O ３ The glass composition according to claim 1, having a total iron content of less than 0.020 wt%, expressed as a content.

9. the below described: The process involves mixing raw materials, the raw materials comprising cullet, sand, soda ash, salt cake, limestone, and dolomite, wherein the dolomite comprises the following: Table 1 The process of melting raw materials to form molten glass; Pour the molten glass onto the molten tin bath; To form glass of a desired thickness and width by controlling the cooling of molten glass and moving the molten glass on the surface of a molten tin bath while applying force to the molten glass; and Remove the glass from the molten bath. A method for forming transparent glass, including, Moreover, the dolomite is low-iron dolomite. Moreover, the glass batch contains Fe within the range listed in the table above. ２ O ３ A method for forming transparent glass containing 9 to 18 wt% low-iron dolomite having a total iron content expressed as content.

10. The method according to claim 9, wherein the raw materials are present in the following amounts. Table 2

11. The method according to claim 9, wherein the sand includes the following: Table 3

12. The method according to claim 9, wherein the salt cake includes the following: Table 4

13. The method according to claim 9, wherein the cullet includes the following: Table 5

14. The method according to claim 9, wherein the limestone includes the following: Table 6

15. The method according to claim 9, wherein the soda ash includes the following: Table 7

16. The method according to claim 9, wherein the raw material further comprises coal or graphite.

17. The method according to claim 16, wherein the coal or graphite is in the range of 0.01 to 0.3 wt%.

18. The method according to claim 16, wherein the coal or graphite comprises the following: Table 8

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