Glass forming method, glass and use thereof

Abstract

The present application relates to the technical field of glass preparation, and discloses a glass forming method, glass and application thereof. The method comprises the following steps: introducing glass liquid into a tin bath containing tin liquid in the presence of protective gas, the tin bath is sequentially provided with a weeding area, a cooling A area and a cooling B area along the length direction, and the glass liquid solidifies after flowing through the weeding area, the cooling A area and the cooling B area on the surface of the tin liquid in sequence to obtain glass. The glass prepared by the method has surface compressive stress not less than 870 MPa, stress layer depth not less than 30 microns, and surface warping not higher than 0.13 mm, and can be applied to a flat display device as a cover plate glass, and the cover plate glass has good drop resistance.

Description

Technical Field

[0001] This invention relates to the field of glass preparation technology, specifically to a glass forming method, glass, and its applications. Background Technology

[0002] The performance of cover glass is mainly related to the compressive stress (CS), depth of stress layer (DOL), and tensile stress (CT). Within a certain range, a higher CS and a greater DOL result in better drop resistance. However, float glass, due to the difference between its air and tin surfaces, exhibits a greater stress difference between the two surfaces in contact with each other. This leads to greater warping and makes it unsuitable for use in flat panel displays.

[0003] CN112159120A discloses a process method for improving warping during ion strengthening of ultra-thin float glass. This method divides the ion strengthening process into a preheating stage, an ion strengthening stage, and a cooling stage. By controlling the heating rate in the preheating stage and the cooling rate in the cooling stage, it alleviates the glass warping problem during the ion strengthening process. However, this method cannot solve the warping problem that occurs during the forming, cooling, and solidification stage.

[0004] Therefore, the ability to produce glass with high pressure stress and low warpage is of great significance for practical production applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem that existing cover glass cannot simultaneously achieve high pressure stress and low warpage.

[0006] To achieve the above objectives, the first aspect of the present invention provides a glass forming method, the method comprising: introducing molten glass into a tin bath containing molten tin in the presence of a protective gas, wherein the tin bath is provided with a drawing zone, a cooling zone A and a cooling zone B in sequence along its length, and wherein the molten glass flows sequentially through the drawing zone, the cooling zone A and the cooling zone B on the surface of the molten tin and then solidifies to obtain glass;

[0007] The initial viscosity of the molten glass is 10. 4.8 Pa.s-10 5.1 Pa.s., the protective gas consists of an inert gas and H2;

[0008] By controlling the temperature of the molten tin in each of the edge-drawing zone, the cooling zone A, and the cooling zone B, the H2 content of the protective gas in each zone, and the temperature and gauge pressure of the protective gas in each zone, the glass produced satisfies the following conditions:

[0009] Taking the surface of the glass that comes into contact with the protective gas during the preparation process as a reference, within a thickness range of 0-5 μm from the surface, 3-15 sites are taken along the thickness direction to measure the sodium content of each site. The distance between each site and the surface is taken as the x value, and the sodium content of each site is taken as the y value. The slope of the fitted linear function is k1.

[0010] Furthermore, taking the surface of the glass that comes into contact with the protective gas during the preparation process as a reference, within a thickness range of 5μm-10μm from the surface, 3-15 sites are taken along the thickness direction to measure the sodium content of each site. The distance between each site and the surface is taken as the x value, and the sodium content of each site is taken as the y value. The slope of the fitted linear function is k2.

[0011] |k1 / k2|>5.

[0012] Preferably, the protective gas includes protective gas I, protective gas II, and protective gas III, wherein protective gas I, protective gas II, and protective gas III are each independently composed of an inert gas and H2;

[0013] In the edge-pulling zone, the upper part of the molten glass is in contact with the protective gas I. The gauge pressure of the protective gas I is controlled to be P1 and the temperature is controlled to be T1. The temperature of the molten tin in contact with the lower part of the molten glass is controlled to be t1. ΔT1 = T1 - t1, and the absolute value of ΔT1 is not greater than 30℃.

[0014] In the cooling zone A, the upper part of the molten glass is in contact with the protective gas II, and the gauge pressure of the protective gas II is controlled to be P2 and the temperature to be T2; the temperature of the molten tin in contact with the lower part of the molten glass is controlled to be t2, ΔT2=T2-t2, and ΔT2 is 20℃-80℃;

[0015] In the cooling zone B, the upper part of the molten glass is in contact with the protective gas III, and the gauge pressure of the protective gas II is controlled at P3 and the temperature at T3; the temperature of the molten tin in contact with the lower part of the molten glass is controlled at t3, ΔT3=T3-t3, and ΔT3 is 20℃-80℃;

[0016] Furthermore, P1 > P2 > P3, T1 > T2 > T3, and the H2 content in protective gas II > the H2 content in protective gas III > the H2 content in protective gas I.

[0017] More preferably, ΔT2 is 50℃-80℃ and ΔT3 is 20℃-50℃.

[0018] Preferably, T1 is 860℃-1050℃; T2 is 700℃-860℃; and T3 is 630℃-700℃.

[0019] Preferably, P1 is 15Pa-25Pa, P2 is 40Pa-50Pa, and P3 is 20Pa-30Pa.

[0020] Preferably, the H2 content in the protective gas I is 2 vol% - 5 vol%.

[0021] Preferably, the H2 content in the protective gas II is 7 vol%-8 vol%.

[0022] Preferably, the H2 content in the protective gas III is 6 vol%-7 vol%.

[0023] Preferably, the flow rate of the molten glass and the area of ​​the edge-pulling zone are controlled so that any portion of the molten glass flows through the edge-pulling zone for 5-7 minutes.

[0024] Preferably, the flow rate of the molten glass and the area of ​​the cooling zone A are controlled so that any portion of the molten glass flows through the cooling zone A for 3-5 minutes.

[0025] Preferably, the flow rate of the molten glass and the area of ​​the cooling zone B are controlled so that any portion of the molten glass flows through the cooling zone B for 2-3 minutes.

[0026] Preferably, the molten glass comprises the following components: 58wt%-63wt% SiO2, 13wt%-20wt% Al2O3, 12.5wt%-16.5wt% Na2O, 3.5wt%-7wt% MgO, 0.3wt%-1.5wt% ZrO2, 0.3wt%-3wt% K2O, and 0-1.0wt% Y2O3.

[0027] Preferably, the edge-pulling conditions in the edge-pulling zone are controlled such that the thickness of the obtained glass is 0.3mm-0.7mm.

[0028] Preferably, the method further includes: subjecting the glass intermediate obtained by solidifying the molten glass after flowing through the edge-pulling zone, the cooling zone A, and the cooling zone B to a chemical strengthening treatment to obtain the glass; wherein the chemical strengthening treatment is performed by immersing the glass intermediate in molten KNO3 at a temperature of 380℃-440℃ for 4h-8h.

[0029] A second aspect of the present invention provides a glass prepared by the method provided in the first aspect of the present invention.

[0030] The third aspect of the present invention provides the application of the glass provided in the second aspect of the present invention in cover glass.

[0031] The glass forming method provided by the present invention controls the special distribution of sodium in the glass to make the surface compressive stress of the glass not less than 870MPa, the stress layer depth not less than 30μm, and the surface warpage not more than 0.13mm. It can be used as cover glass in flat panel display devices, and the cover glass has good drop resistance and impact resistance. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a preferred glass forming process provided by a specific embodiment of the present invention. Detailed Implementation

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] As previously described, a first aspect of the present invention provides a glass forming method, such as... Figure 1 As shown, the method includes: introducing molten glass into a tin bath containing molten tin in the presence of a protective gas, wherein the tin bath is provided with a drawing zone, a cooling zone A and a cooling zone B in sequence along its length, and the molten glass solidifies after flowing sequentially through the drawing zone, the cooling zone A and the cooling zone B on the surface of the molten tin to obtain glass;

[0035] The initial viscosity of the molten glass is 10. 4.8 Pa.s-10 5.1 Pa.s., the protective gas consists of an inert gas and H2;

[0036] By controlling the temperature of the molten tin in each of the edge-drawing zone, the cooling zone A, and the cooling zone B, the H2 content of the protective gas in each zone, and the temperature and gauge pressure of the protective gas in each zone, the glass produced satisfies the following conditions:

[0037] Taking the surface of the glass that comes into contact with the protective gas during the preparation process as a reference, within a thickness range of 0-5 μm from the surface, 3-10 sites are taken along the thickness direction to measure the sodium content of each site. The distance between each site and the surface is taken as the x value, and the sodium content of each site is taken as the y value. The slope of the fitted linear function is k1.

[0038] Furthermore, taking the surface of the glass that comes into contact with the protective gas during the preparation process as a reference, within a thickness range of 5μm-10μm from the surface, 3-10 sites are taken along the thickness direction to measure the sodium content of each site. The slope of the fitted linear function is k2, with the distance between each site and the surface as the x value and the sodium content of each site as the y value.

[0039] |k1 / k2|>5.

[0040] The inventors of this invention discovered that the fundamental cause of glass warping lies in the fact that during the float glass production process, the side of the glass in contact with molten tin (the tin side) has a larger amount of tin ions adhering to or penetrating into the glass surface. These tin ions hinder the exchange of sodium and potassium ions during ion strengthening. Conversely, the side of the glass in contact with the protective gas (the air side), without the obstruction of tin ions, allows for a greater degree of sodium and potassium ion exchange compared to the tin side, thus causing glass warping. To address this, the inventors propose a glass forming method. During the glass forming and cooling process, this method controls the temperature of the molten tin in each of the edge-drawing zone, the H2 content of the protective gas in each of the three zones, as well as the temperature and gauge pressure of the protective gas in each zone, to redistribute sodium ions near the air side of the glass in a specific manner. This results in glass that maintains high surface compressive stress (CS) and depth of stress layer (DOL) while also exhibiting low warping.

[0041] It should be noted that the present invention does not impose special requirements on the testing method for sodium content at different sites in the glass. Exemplarily, the sodium content at different sites in the glass is tested according to the following method: the glass sample prepared by the present invention is etched with hydrofluoric acid at a concentration of 2.5 wt% to obtain glass surfaces at different thicknesses from the air surface of the glass sample (e.g., glass surfaces at distances of 0 μm, 2 μm, 5 μm, 8 μm, 10 μm, 12 μm, and 15 μm from the air surface, respectively). Then, the sodium content corresponding to the glass surfaces at different thicknesses is measured using an X-ray fluorescence spectrometer. Exemplarily, the X-ray fluorescence spectrometer is an MXF-2400 X-ray fluorescence spectrometer purchased from Shimadzu Corporation, Japan.

[0042] It should also be noted that, in this invention, the “initial viscosity” of the molten glass refers to the viscosity of the molten glass when it enters the tin bath; the inert gas refers to at least one of helium, neon, argon, and nitrogen.

[0043] According to a particularly preferred embodiment of the invention, the inert gas is nitrogen.

[0044] According to some preferred embodiments of the present invention, the protective gas includes protective gas I, protective gas II, and protective gas III, wherein protective gas I, protective gas II, and protective gas III are each independently composed of an inert gas and H2;

[0045] In the edge-pulling zone, the upper part of the molten glass is in contact with the protective gas I. The gauge pressure of the protective gas I is controlled to be P1 and the temperature is controlled to be T1. The temperature of the molten tin in contact with the lower part of the molten glass is controlled to be t1. ΔT1 = T1 - t1, and the absolute value of ΔT1 is not greater than 30℃.

[0046] In the cooling zone A, the upper part of the molten glass is in contact with the protective gas II, and the gauge pressure of the protective gas II is controlled to be P2 and the temperature to be T2; the temperature of the molten tin in contact with the lower part of the molten glass is controlled to be t2, ΔT2=T2-t2, and ΔT2 is 20℃-80℃;

[0047] In the cooling zone B, the upper part of the molten glass is in contact with the protective gas III, and the gauge pressure of the protective gas II is controlled at P3 and the temperature at T3; the temperature of the molten tin in contact with the lower part of the molten glass is controlled at t3, ΔT3=T3-t3, and ΔT3 is 20℃-80℃;

[0048] Furthermore, P1 > P2 > P3, T1 > T2 > T3, and the H2 content in protective gas II > the H2 content in protective gas III > the H2 content in protective gas I.

[0049] The inventors of this invention have discovered that the distribution of sodium in the manufactured glass can be adjusted by modifying the temperature of the molten tin in each of the edge-pulling zone, cooling zone A, and cooling zone B, the H2 content of the protective gas in each zone, and the temperature and gauge pressure of the protective gas in each zone. Under these preferred conditions, the migration and enrichment of sodium in the molten glass towards the air surface can be further enhanced, resulting in a higher alkali metal content in the manufactured glass at a distance of 0-5 μm from the air surface compared to the sodium content at a distance of 5-10 μm from the air surface. This creates a high-low-high sodium content distribution structure in the glass from the air surface to the tin surface, thereby enabling the manufactured glass to maintain high surface compressive stress and stress layer depth while also exhibiting low warpage.

[0050] According to a particularly preferred embodiment of the present invention, the absolute value of ΔT1 is 0.

[0051] According to some preferred embodiments of the present invention, ΔT2 is 50℃-80℃, and ΔT3 is 20℃-50℃. The inventors have found that under these preferred conditions, the resulting glass has lower warpage, higher surface compressive stress and stress layer depth, and better drop resistance.

[0052] According to some preferred embodiments of the present invention, T1 is 860℃-1050℃; T2 is 700℃-860℃; and T3 is 630℃-700℃.

[0053] According to some preferred embodiments of the present invention, P1 is 15Pa-25Pa, P2 is 40Pa-50Pa, and P3 is 20Pa-30Pa.

[0054] According to some preferred embodiments of the present invention, the H2 content in the protective gas I is 2 vol%-5 vol%.

[0055] According to some preferred embodiments of the present invention, the H2 content in the protective gas II is 7 vol%-8 vol%.

[0056] Furthermore, the inventors discovered that, in this preferred embodiment, the protective gas II with a specific H2 content can increase the content of hydroxyl groups on the surface of the molten glass. The specific reaction equation is as follows: Si-O-Si + H2 → Si-OH + Si-H. The large number of hydroxyl groups on the surface of the molten glass can further disrupt the glass surface structure, causing the [SiO4] structure near the air surface of the molten glass to break up, increasing the interionic gaps, and facilitating the transport of alkali metal elements (such as Na ions) from inside the glass to the air surface. This results in a high-low-high distribution structure of sodium content from the air surface to the tin surface in the glass, thereby producing glass with lower warpage.

[0057] According to some preferred embodiments of the present invention, the H2 content in the protective gas III is 6 vol%-7 vol%. Under these preferred conditions, the protective gas III with this specific H2 content can both further increase the hydroxyl groups on the surface of the molten glass and appropriately solidify the molten glass.

[0058] According to some preferred embodiments of the present invention, the flow rate of the molten glass and the area of ​​the edge-pulling zone are controlled such that any portion of the molten glass flows through the edge-pulling zone for 5-7 minutes.

[0059] According to some preferred embodiments of the present invention, the flow rate of the molten glass and the area of ​​the cooling zone A are controlled such that any portion of the molten glass flows through the cooling zone A for 3-5 minutes.

[0060] According to some preferred embodiments of the present invention, the flow rate of the molten glass and the area of ​​the cooling zone B are controlled such that any portion of the molten glass flows through the cooling zone B for 2-3 minutes.

[0061] According to some preferred embodiments of the present invention, the molten glass comprises the following components: 58wt%-63wt% SiO2, 13wt%-20wt% Al2O3, 12.5wt%-16.5wt% Na2O, 3.5wt%-7wt% MgO, 0.3wt%-1.5wt% ZrO2, 0.3wt%-3wt% K2O, and 0-1.0wt% Y2O3.

[0062] According to some preferred embodiments of the present invention, the edge-pulling conditions of the edge-pulling zone are controlled so that the thickness of the obtained glass is 0.3mm-0.7mm.

[0063] According to some preferred embodiments of the present invention, the method further includes: subjecting the glass intermediate obtained by solidifying the molten glass after passing through the edge-drawing zone, the cooling zone A, and the cooling zone B to a chemical strengthening treatment to obtain the glass;

[0064] The chemical strengthening treatment involves immersing the glass intermediate in molten KNO3 at a temperature of 380℃-440℃ for 4-8 hours.

[0065] More preferably, in the chemical strengthening treatment, the immersion temperature is 400℃-420℃ and the immersion time is 5h-7h.

[0066] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials used are commercially available products.

[0067] The molten glass is composed of 60 wt% SiO2, 16.2 wt% Al2O3, 15.4 wt% Na2O, 4 wt% MgO, 1.2 wt% ZrO2, 3 wt% K2O, and 0.2 wt% Y2O3, with an initial viscosity of 10. 5 Pa.s.

[0068] The thickness of the glass prepared in the following examples and comparative examples is 0.7 mm.

[0069] Example 1

[0070] S1: As Figure 1 As shown, in the presence of a protective gas, the molten glass is introduced into a tin bath containing molten tin. The tin bath is provided with a finning zone, a cooling zone A, and a cooling zone B in sequence along its length. The molten glass flows through the finning zone, the cooling zone A, and the cooling zone B in sequence on the surface of the molten tin and then solidifies to obtain a glass intermediate.

[0071] S2: The glass intermediate is immersed in molten KNO3 at a temperature of 400°C for 6 hours to obtain glass L1;

[0072] By controlling the temperature of the molten tin in each of the edge-drawing zone, the cooling zone A, and the cooling zone B, the H2 content of the protective gas in each zone, and the temperature and gauge pressure of the protective gas in each zone, the glass produced satisfies the following conditions:

[0073] Taking the surface of the glass that comes into contact with the protective gas during the preparation process as a reference, within a thickness range of 0-5 μm from the surface, 3-15 sites are taken along the thickness direction to measure the sodium content of each site. The distance between each site and the surface is taken as the x value, and the sodium content of each site is taken as the y value. The slope of the fitted linear function is k1.

[0074] Furthermore, taking the surface of the glass that comes into contact with the protective gas during the preparation process as a reference, within a thickness range of 5μm-10μm from the surface, 3-15 sites are taken along the thickness direction to measure the sodium content of each site. The distance between each site and the surface is taken as the x value, and the sodium content of each site is taken as the y value. The slope of the fitted linear function is k2.

[0075] |k1 / k2|>5.

[0076] The protective gas includes protective gas I, protective gas II, and protective gas III, each of which is independently composed of an inert gas and H2.

[0077] In the edge-pulling zone, the upper part of the molten glass is in contact with the protective gas I. The gauge pressure of the protective gas I is controlled to be P1 and the temperature is controlled to be T1. The temperature of the molten tin in contact with the lower part of the molten glass is controlled to be t1. ΔT1 = T1 - t1, and ΔT1 is 0℃.

[0078] In the cooling zone A, the upper part of the molten glass is in contact with protective gas II, and the gauge pressure of protective gas II is controlled to be P2 and the temperature to be T2; the temperature of the molten tin in contact with the lower part of the molten glass is controlled to be t2, ΔT2=T2-t2;

[0079] In the cooling zone B, the upper part of the molten glass is in contact with the protective gas III, and the gauge pressure of the protective gas II is controlled at P3 and the temperature at T3; the temperature of the molten tin in contact with the lower part of the molten glass is controlled at t3, ΔT3=T3-t3;

[0080] The H2 content in protective gas I is V1, the H2 content in protective gas II is V2, and the H2 content in protective gas III is V3.

[0081] The flow rate of the molten glass and the area of ​​the edge-pulling zone are controlled such that the time for any part of the molten glass to flow through the edge-pulling zone is h1; the flow rate of the molten glass and the area of ​​the cooling zone A are controlled such that the time for any part of the molten glass to flow through the cooling zone A is h2; and the flow rate of the molten glass and the area of ​​the cooling zone B are controlled such that the time for any part of the molten glass to flow through the cooling zone B is h3.

[0082] Specifically, the parameters are shown in Table 1 below.

[0083] Examples 2-5

[0084] The process was carried out in accordance with Example 1, except that ΔT2, ΔT3, P2, P3 and |k1 / k2| were adjusted, while other parameters were the same as in Example 1, to produce glass L2, L3, L4 and L5 respectively.

[0085] Comparative Examples 1-3

[0086] The process was carried out in accordance with Example 1, except that ΔT2, ΔT3, P2, P3, the H2 content in protective gas II, the H2 content in protective gas III, and |k1 / k2| were adjusted. Other parameters were the same as in Example 1, and glasses DL1-DL3 were prepared respectively.

[0087] Test case

[0088] The glasses prepared in the above embodiments and comparative examples were subjected to the following tests:

[0089] Warpage test: measured in accordance with standards GB / T 25257-2010 and GB / T 6620-2009. Instrument used: flatness meter, purchased from Hexagon Measurement Technology Co., Ltd., model Accura L;

[0090] Surface compressive stress (CS) and stress layer depth (DOL) tests were conducted in accordance with standards GB / T 18144-2008 and ASTM1422C-99. The instrument used was a surface stress meter, purchased from Orihara Corporation, Japan, model FSM-6000.

[0091] The specific test data is shown in Table 1 below.

[0092] Table 1

[0093]

[0094]

[0095] As can be seen from the results in Table 1, the warpage of the glass produced by the glass forming method provided in the embodiments of the present invention is no higher than 0.13 mm, which is significantly lower than the warpage of the glass produced by the glass forming method provided in the comparative example. Furthermore, the surface compressive stress of the glass produced by the glass forming method provided in the embodiments of the present invention is no lower than 870 MPa, and the stress layer depth is no lower than 30 μm. It can be used as a glass cover for a flat panel display device and has good drop resistance.

[0096] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A glass forming method, characterized in that, The method includes: In the presence of a protective gas, molten glass is introduced into a tin bath containing molten tin. The tin bath is provided with a finning zone, a cooling zone A, and a cooling zone B in sequence along its length. The molten glass flows sequentially through the finning zone, the cooling zone A, and the cooling zone B on the surface of the molten tin and then solidifies to obtain glass. The initial viscosity of the molten glass is 10. 4.8 Pa·s-10 5.1 Pa·s, wherein the protective gas consists of an inert gas and H2; the glass melt contains the following components: 58wt%-63wt% SiO2, 13wt%-20wt% Al2O3, 12.5wt%-16.5wt% Na2O, 3.5wt%-7wt% MgO, 0.3wt%-1.5wt% ZrO2, 0.3wt%-3wt% K2O and 0-1.0wt% Y2O3; By controlling the temperature of the molten tin in each of the edge-drawing zone, the cooling zone A, and the cooling zone B, the H2 content of the protective gas in each zone, and the temperature and gauge pressure of the protective gas in each zone, the glass produced satisfies the following conditions: Taking the surface of the glass that comes into contact with the protective gas during the preparation process as a reference, within a thickness range of 0-5 μm from the surface, 3-15 sites are taken along the thickness direction to measure the sodium content of each site. The distance between each site and the surface is taken as the x value, and the sodium content of each site is taken as the y value. The slope of the fitted linear function is k1. Furthermore, taking the surface of the glass that comes into contact with the protective gas during the preparation process as a reference, within a thickness range of 5μm-10μm from the surface, 3-15 sites are taken along the thickness direction to measure the sodium content of each site. The distance between each site and the surface is taken as the x value, and the sodium content of each site is taken as the y value. The slope of the fitted linear function is k2. |k1 / k2| > 5.

2. The method according to claim 1, characterized in that, The protective gas includes protective gas I, protective gas II, and protective gas III, each of which is independently composed of an inert gas and H2. In the edge-pulling zone, the upper part of the molten glass is in contact with protective gas I. The gauge pressure of protective gas I is controlled at P1 and the temperature at T1. The temperature of the molten tin in contact with the lower part of the molten glass is controlled at t1. T1 = T1 - t1, The absolute value of T1 is no greater than 30℃; In cooling zone A, the upper part of the molten glass is in contact with protective gas II, and the gauge pressure of protective gas II is controlled at P2 and the temperature at T2; the temperature of the molten tin in contact with the lower part of the molten glass is controlled at t2. T2 = T2 - t2, T2 is 20℃-80℃; In the cooling zone B, the upper part of the molten glass is in contact with protective gas III, and the gauge pressure of protective gas II is controlled at P3 and the temperature at T3; the temperature of the molten tin in contact with the lower part of the molten glass is controlled at t3. T3 = T3 - t3, T3 is 20℃-80℃; Furthermore, P1 > P2 > P3, T1 > T2 > T3, and the H2 content in protective gas II > the H2 content in protective gas III > the H2 content in protective gas I.

3. The method according to claim 2, characterized in that, T2 is 50℃-80℃. T3 is 20℃-50℃.

4. The method according to any one of claims 2-3, characterized in that, T1 is 860℃-1050℃; T2 is 700℃-860℃; T3 is 630℃-700℃. And / or, P1 is 15Pa-25Pa, P2 is 40Pa-50Pa, and P3 is 20Pa-30Pa.

5. The method according to claim 2, characterized in that, The H2 content in the protective gas I is 2 vol% - 5 vol%. And / or, the H2 content in the protective gas II is 7 vol%-8 vol%. And / or, the H2 content in the protective gas III is 6 vol%-7 vol%.

6. The method according to any one of claims 1-3, characterized in that, The flow rate of the molten glass and the area of ​​the edge-pulling zone are controlled so that the time h1 for any part of the molten glass to flow through the edge-pulling zone is 5 min-7 min; And / or, control the flow rate of the molten glass and the area of ​​the cooling zone A so that the time h2 for any part of the molten glass to flow through the cooling zone A is 3 min to 5 min; And / or, control the flow rate of the molten glass and the area of ​​the cooling zone B so that the time h3 for any portion of the molten glass to flow through the cooling zone B is 2 min to 3 min.

7. The method according to any one of claims 1-3, characterized in that, The edge-pulling conditions in the edge-pulling zone are controlled to obtain glass with a thickness of 0.3mm-0.7mm.

8. The method according to any one of claims 1-3, characterized in that, The method further includes: chemically strengthening the glass intermediate obtained by solidifying the molten glass after it flows through the edge-drawing zone, the cooling zone A, and the cooling zone B, to obtain the glass; The chemical strengthening treatment involves immersing the glass intermediate in molten KNO3 at a temperature of 380℃-440℃ for 4-8 hours.

9. Glass prepared by the method according to any one of claims 1-8.

10. The use of the glass of claim 9 in cover glass.

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