Composite clarifier system with phased gas release for production of TFT alkali-free glass substrate, preparation method and application thereof

Abstract

The present invention discloses a composite clarifier system with phased gas release for the production of TFT alkali-free glass substrates, as well as its preparation method and application. The composite clarifier system includes a SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier, a nano-scale Sb2O3-loaded Al2O3 dispersion, a CeO2 / SnS2 composite agent, and CaCl2. After using the composite clarifier system of the present invention, the bubble density of the prepared TFT alkali-free glass substrate is increased from the conventional 8-12 / cm 3 Reduced to 0.4 / cm 3 The residual amount of clarifier is reduced by 45-55%, and no streaks or stone defects are observed; the strain point of the glass is increased by 16-19℃, and the high temperature viscosity curve meets the requirements of secondary processing of TFT substrates, reducing Fe 2+ The generation of colored ions such as iodine increases the transmittance by 0.6-0.8%, further improving the optical properties of the glass.

Description

Technical Field

[0001] The present invention relates to the field of glass technology, and in particular to a composite clarifier system with phased gas release for producing TFT alkali-free glass substrates, and a preparation method and application thereof. Background Art

[0002] In the glass manufacturing industry, traditional fining agents such as Sb2O3, CaSO4, and SnO2 are widely used to remove bubbles from glass melts to improve the transparency and quality of the glass. However, these traditional fining agents have two key flaws in practical applications that seriously affect the final performance of the glass product.

[0003] Defect 1: Insufficient early decomposition and bubble rise rate

[0004] Premature decomposition: These traditional fining agents begin to decompose in the early stages of glass melting (temperatures below 1400°C). For example, Sb2O3 decomposes at high temperatures to produce O2, and CaSO4 decomposes to produce SO3 and other gases.

[0005] Bubble rising is blocked: because the viscosity of the glass liquid is high (usually greater than 10 2 The high viscosity of the glass makes it difficult for bubbles to quickly rise to the surface and escape, resulting in residual bubbles in the glass, which affects its transparency and uniformity.

[0006] Defect 2: Insufficient clarification effect and residual problems in the high temperature stage

[0007] Depletion of active ingredients: When the glass melt enters the high-temperature, low-viscosity stage (temperature exceeding 1550°C), the active ingredients of traditional fining agents are basically exhausted. This means that they can no longer generate the sustained gas pressure required to maintain bubble growth, resulting in a decrease in fining effect.

[0008] Residual clarifiers and crystallization risk: To compensate for the lack of clarification during the high-temperature stage, the conventional approach is to increase the amount of clarifier. However, this can result in undecomposed clarifier residues in the glass. These residues can become heterogeneous crystal nuclei, inducing crystallization (increasing the crystallization rate by 0.3-0.5%), thereby reducing the transparency and mechanical strength of the glass.

[0009] Antimony colloid formation: In particular, Sb2O3 is easily reduced to metallic antimony in a reducing atmosphere, forming metallic antimony colloids. These colloidal particles scatter light, causing a 1.2-1.8% loss in the glass's transmittance, further affecting the glass's optical properties.

[0010] In summary, the problems of traditional clarifiers, such as early decomposition during the glass melting process and insufficient clarification at high temperatures, not only affect the transparency and uniformity of the glass but also lead to additional problems such as crystallization and loss of light transmittance. Therefore, the development of new, efficient clarifiers to overcome these shortcomings has become an important research direction in the glass manufacturing industry. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a composite clarifier system with phased gas release for the production of TFT alkali-free glass substrates, as well as its preparation method and application. The prepared TFT alkali-free glass substrate has a reduced bubble density, reduced clarifier residue, increased glass strain point, and a high-temperature viscosity curve that meets the requirements of secondary processing of TFT substrates, reducing Fe 2+ The generation of colored ions such as iodine and iodine increases the light transmittance.

[0012] The technical solution of the present invention is:

[0013] In a first aspect, the present invention provides a method for preparing a composite clarifier system with staged gas release for the production of TFT alkali-free glass substrates, wherein the composite clarifier system comprises a SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier, a nano-scale Sb2O3-loaded Al2O3 dispersion, a CeO2 / SnS2 composite agent, and CaCl2 in a mass ratio of (0.3-0.5):(0.15-0.25):(0.08-0.12):(0.1-0.3);

[0014] The preparation method of SiO2 / ZrO2 coated SnO2-CaSO4 core-shell structure clarifier adopts sol-gel method to prepare SnO2-CaSO4 core-shell particles. By adjusting the thickness of SiO2 / ZrO2 coating layer, the decomposition temperature of CaSO4 is controlled from the conventional 1350℃ to 1480-1520℃. The coating layer is dissolved by the glass network in the melt at 1550℃, releasing Ca 2+ As a network modifier; specifically comprising the following steps:

[0015] S1 Preparation of SnO2 sol: Prepare SnCl2·2H2O solution, add alkaline solution dropwise under stirring condition, adjust the solution pH to 8-9, and continue stirring to form a stable SnO2 sol;

[0016] S2 prepares CaSO4 precursor solution;

[0017] Formation of S3 core-shell particles: Add SnO2 sol to CaSO4 precursor solution and stir in a constant temperature water bath at 50-60℃ for 3-4h to form a SnO2-CaSO4 core-shell structure precursor;

[0018] Treatment of S4 coating layer: Add silicon source and zirconium source to the above reaction system, react under stirring conditions for 1-2 hours, and form SiO2 / ZrO2 coating layer on the surface of SnO2-CaSO4 core-shell particles;

[0019] S5 washing and drying: After the reaction is completed, the obtained precipitate is washed, dried, ground and sieved to obtain a SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier with a particle size D50 of 5-8 μm;

[0020] The preparation method of nano-scale Sb2O3-loaded Al2O3 dispersion comprises the following steps:

[0021] (1) Preparation of a porous Al2O3 carrier: Pseudo-boehmite and additives are uniformly mixed to form a green body, which is pre-sintered at 500-600°C for 2-3 hours and then heated to 1200-1300°C for 4-6 hours to obtain a porous Al2O3 carrier;

[0022] (2) Loading Sb2O3 nanoparticles: Sb2O3 nanoparticles are dispersed in an organic solvent to prepare a dispersion, and the porous Al2O3 carrier is immersed in the dispersion. Ultrasonic vibration is applied to fully load the Sb2O3 nanoparticles in the pores and on the surface of the porous Al2O3 carrier;

[0023] (3) Surface treatment and drying: After washing and drying, nano-scale Sb2O3-loaded Al2O3 dispersion is obtained. Due to the chemical bonding between the surface hydroxyl groups of Sb2O3 nanoparticles and Al2O3, the initial oxygen release temperature is increased from 900°C to 1300°C, and oxygen release continues up to 1450°C.

[0024] Preparation method of CeO2 / SnS2 composite agent, SnS2 is used as high temperature (>1500℃) auxiliary foaming agent, and the oxidation catalysis of CeO2 is used to promote the decomposition of SnS2 to release SO2 gas. 4+ / Ce 3+ Redox couple can adjust the oxygen partial pressure of melt (ΔPO2=10 -6 -10 -4 atm); specifically comprising the following steps:

[0025] 1) Mixed grinding: Grind CeO2 and SnS2 powders using anhydrous ethanol as a grinding aid to uniformly mix the two powders;

[0026] 2) Drying treatment: The mixed powder is dried to remove the anhydrous ethanol therein to obtain a CeO2 / SnS2 composite.

[0027] Preferably, in step S1, the concentration of the SnCl2·2H2O solution is 0.5-1 mol / L; the alkaline solution is ammonia water; and the particle size of the SnO2 sol is 10-20 nm.

[0028] Preferably, in step S2, the concentration of the CaSO4 precursor solution is 0.2-0.3 mol / L.

[0029] Preferably, in step S4, the silicon source is tetraethyl orthosilicate (TEOS), the zirconium source is zirconium oxychloride (ZrOCl2·8H2O), and the molar ratio of tetraethyl orthosilicate to zirconium oxychloride is (1-3):1.

[0030] Preferably, in step S5, the drying temperature is 80-100° C., and the drying time is 12-16 hours.

[0031] Preferably, in step (1), the additive is sesbania powder or citric acid, and the mass of the additive is 3-8% of the mass of pseudo-boehmite; and the pore size of the porous Al2O3 carrier is 4-6 nm.

[0032] Preferably, in step (2), the particle size of the Sb2O3 nanoparticles is 20-50 nm; the organic solvent is anhydrous ethanol; the concentration of the dispersion is 0.05-0.1 g / mL; the ultrasonic oscillation treatment time is 30-60 min; and in step (3), the drying temperature is 60-80°C and the drying time is 8-12 h.

[0033] Preferably, in step 1), the proportion of SnS2 in the two powders is 0.05-0.1 wt.%; the grinding is performed for 30-60 min; and in step 2), the drying temperature is 60-80° C. and the drying time is 4-6 h.

[0034] In a second aspect, the present invention provides a composite clarifier system with phased gas release for the production of TFT alkali-free glass substrates, which is prepared by the above-mentioned preparation method.

[0035] In a third aspect, the present invention also provides an application of the composite clarifier system with phased gas release for the production of the above-mentioned TFT alkali-free glass substrate. 0.6-1.2 wt.% of the composite clarifier system is added to the SiO2-Al2O3-B2O3-RO system alkali-free glass batch. When the glass is melted, the temperature is first raised from room temperature to 1400-1450°C at a rate of 10-15°C / min and kept warm for 1-2 hours; then the temperature is raised to 1550-1600°C at a rate of 5-8°C / min and kept warm for 2-3 hours; finally, the temperature is lowered to 1500-1530°C at a rate of 3-5°C / min and clarified and homogenized for 1-2 hours.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] After using the composite clarifier system of the present invention, the bubble density of the prepared TFT alkali-free glass substrate is increased from the conventional 8-12 / cm 3 Reduced to 0.4 / cm 3 The residual amount of clarifier is reduced by 45-55%, and no streaks or stone defects are observed; the strain point of glass is increased by 16-19℃, and the high temperature viscosity curve meets the requirements of secondary processing of TFT substrate (104.5dPa·s corresponds to a temperature deviation of no more than ±2℃), and Fe is reduced. 2+ The generation of colored ions such as iodine and nitrite increases the light transmittance by 0.6-0.8%, further improving the optical properties of the glass. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0039] Example 1

[0040] The present embodiment provides a method for preparing a composite clarifier system with staged gas release for producing TFT alkali-free glass substrates, wherein the composite clarifier system comprises a SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier, a nano-scale Sb2O3-loaded Al2O3 dispersion, a CeO2 / SnS2 composite agent, and CaCl2 in a mass ratio of 0.3:0.15:0.08:0.1;

[0041] The preparation method of a SiO2 / ZrO2 coated SnO2-CaSO4 core-shell structure clarifier comprises the following steps:

[0042] S1 Preparation of SnO2 sol: Dissolve SnCl2·2H2O in water to prepare a solution with a concentration of 0.5 mol / L. Slowly add ammonia water dropwise while stirring to adjust the solution pH to 8. Continue stirring for 1 h to form a stable SnO2 sol with a particle size of 10 nm.

[0043] S2 Preparation of CaSO4 precursor solution: Weigh calcium sulfate, add deionized water, heat and stir until completely dissolved, and prepare a CaSO4 solution with a concentration of 0.2 mol / L;

[0044] Formation of S3 core-shell particles: SnO2 sol was added to CaSO4 precursor solution and stirred in a constant temperature water bath at 50°C for 3 hours. During the reaction, CaSO4 gradually deposited on the surface of SnO2 particles to form a precursor of SnO2-CaSO4 core-shell structure;

[0045] Treatment of the S4 coating layer: TEOS and ZrOCl2·8H2O at a molar ratio of 1:1 were added to the above reaction system and reacted under stirring for 1 h to hydrolyze and condense the silicon source and zirconium source to form a SiO2 / ZrO2 coating layer on the surface of the SnO2-CaSO4 core-shell particles;

[0046] S5 washing and drying: After the reaction is completed, the obtained precipitate is washed by centrifugal separation and repeatedly washed with deionized water until no impurity ions are detected in the washing liquid; the precipitate is then dried in an oven at 80°C for 12 hours to obtain dry SnO2-CaSO4 core-shell particles; finally, SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier with a particle size of D50 = 5 μm is obtained by mechanical grinding and sieving.

[0047] The preparation method of nano-scale Sb2O3-loaded Al2O3 dispersion comprises the following steps:

[0048] (1) Preparation of a porous Al2O3 support: Pseudoboehmite and sesbania powder were uniformly mixed to form a green body, wherein the mass of sesbania powder was 3% of the mass of the pseudoboehmite; the green body was pre-sintered at 500°C for 2 h, then heated to 1200°C and sintered for 4 h to obtain a porous Al2O3 support with a pore size of 4 nm;

[0049] (2) Loading Sb2O3 nanoparticles: Sb2O3 nanoparticles with a particle size of 20 nm were dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 0.05 g / mL. The porous Al2O3 support was immersed in the dispersion and ultrasonically vibrated for 30 min to fully load the Sb2O3 nanoparticles in the pores and on the surface of the porous Al2O3 support.

[0050] (3) Surface treatment and drying: The excess Sb2O3 nanoparticles on the surface were rinsed with anhydrous ethanol and then dried in an oven at 60°C for 8 h to obtain nano-scale Sb2O3-loaded Al2O3 dispersion.

[0051] The preparation method of CeO2 / SnS2 composite agent comprises the following steps:

[0052] 1) Mixed grinding: CeO2 and SnS2 powders were placed in an agate mortar, anhydrous ethanol was added as a grinding aid, and the mixture was fully ground for 30 minutes to uniformly mix the two powders; the proportion of SnS2 powder was 0.05 wt.%;

[0053] 2) Drying treatment: The mixed powder was dried in an oven at 60° C. for 4 h to remove the anhydrous ethanol therein to obtain a CeO 2 / SnS 2 composite.

[0054] When the composite clarifier system of this embodiment is used, the composite clarifier system is added to a SiO2-Al2O3-B2O3-RO alkali-free glass batch (SiO2 68 wt.%, Al2O3 15 wt.%, B2O3 10 wt.%, RO (MgO 3 wt.%, CaO 2 wt.%, SrO 1 wt.%, BaO 1 wt.%), in an amount of 0.63 wt.% of the batch. When melting the glass, the temperature is first raised from room temperature to 1400°C at a rate of 10°C / min and held at that temperature for 1 hour; then raised to 1550°C at a rate of 5°C / min and held at that temperature for 2 hours; finally, the temperature is lowered to 1500°C at a rate of 3°C / min and clarified and homogenized for 1 hour.

[0055] The glass prepared in this embodiment was tested for performance and compared with that in comparative example 1. The test results showed that the bubble density was 0.4 / cm 3 , the residual amount of clarifier is reduced by 45%, the strain point of glass is increased by 16℃, the temperature deviation corresponding to 104.5dPa·s is ±2℃, and the transmittance is increased by 0.6%.

[0056] Example 2

[0057] The present embodiment provides a method for preparing a composite clarifier system with staged gas release for the production of TFT alkali-free glass substrates, wherein the composite clarifier system comprises a SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier in a mass ratio of 0.4:0.2:0.1:0.2, a nano-scale Sb2O3-loaded Al2O3 dispersion, a CeO2 / SnS2 composite agent, and CaCl2;

[0058] The preparation method of a SiO2 / ZrO2 coated SnO2-CaSO4 core-shell structure clarifier comprises the following steps:

[0059] S1 Preparation of SnO2 sol: Dissolve SnCl2·2H2O in water to prepare a solution with a concentration of 0.75 mol / L. Slowly add ammonia water dropwise while stirring to adjust the solution pH to 8.5. Continue stirring for 1.5 h to form a stable SnO2 sol with a particle size of 15 nm.

[0060] S2 Preparation of CaSO4 precursor solution: Weigh calcium sulfate, add deionized water, heat and stir until completely dissolved, and prepare a CaSO4 solution with a concentration of 0.25 mol / L;

[0061] Formation of S3 core-shell particles: SnO2 sol was added to CaSO4 precursor solution and stirred in a constant temperature water bath at 55°C for 3.5 hours. During the reaction, CaSO4 gradually deposited on the surface of SnO2 particles to form a SnO2-CaSO4 core-shell structure precursor;

[0062] Treatment of the S4 coating layer: TEOS and ZrOCl2·8H2O at a molar ratio of 2:1 were added to the above reaction system and reacted under stirring for 1.5 h to hydrolyze and condense the silicon source and zirconium source to form a SiO2 / ZrO2 coating layer on the surface of the SnO2-CaSO4 core-shell particles;

[0063] S5 washing and drying: After the reaction is completed, the obtained precipitate is washed by centrifugal separation and repeatedly washed with deionized water for 3-5 times until no impurity ions are detected in the washing liquid; the precipitate is then dried in an oven at 90°C for 14 hours to obtain dry SnO2-CaSO4 core-shell particles; finally, SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier with a particle size D50 = 6.5 μm is obtained by mechanical grinding and sieving.

[0064] The preparation method of nano-scale Sb2O3-loaded Al2O3 dispersion comprises the following steps:

[0065] (1) Preparation of a porous Al2O3 support: Pseudoboehmite and citric acid were uniformly mixed to form a green body, wherein the mass of sesbania powder was 5.5% of the mass of the pseudoboehmite; the green body was pre-sintered at 550°C for 2.5 hours, then heated to 1250°C and sintered for 5 hours to obtain a porous Al2O3 support with a pore size of 5 nm;

[0066] (2) Loading Sb2O3 nanoparticles: Sb2O3 nanoparticles with a particle size of 35 nm were dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 0.75 g / mL. The porous Al2O3 support was immersed in the dispersion and ultrasonically vibrated for 45 min to fully load the Sb2O3 nanoparticles in the pores and on the surface of the porous Al2O3 support.

[0067] (3) Surface treatment and drying: The excess Sb2O3 nanoparticles on the surface were rinsed with anhydrous ethanol and then dried in an oven at 70°C for 10 h to obtain nano-scale Sb2O3-loaded Al2O3 dispersion.

[0068] The preparation method of CeO2 / SnS2 composite agent comprises the following steps:

[0069] 1) Mixed grinding: CeO2 and SnS2 powders were placed in an agate mortar, anhydrous ethanol was added as a grinding aid, and the mixture was thoroughly ground for 45 minutes to uniformly mix the two powders; the proportion of SnS2 powder was 0.075 wt.%;

[0070] 2) Drying treatment: The mixed powder was dried in an oven at 70° C. for 5 h to remove the anhydrous ethanol therein to obtain a CeO 2 / SnS 2 composite.

[0071] When the composite clarifier system of this embodiment is used, the composite clarifier system is added to a SiO2-Al2O3-B2O3-RO alkali-free glass batch (SiO2 68 wt.%, Al2O3 15 wt.%, B2O3 10 wt.%, RO (MgO 3 wt.%, CaO 2 wt.%, SrO 1 wt.%, BaO 1 wt.%), in an amount of 0.9 wt.% of the batch. When melting the glass, the temperature is first raised from room temperature to 1425°C at a rate of 12°C / min and held at that temperature for 1.5 hours; then raised to 1575°C at a rate of 6°C / min and held at that temperature for 2.5 hours; finally, the temperature is lowered to 1515°C at a rate of 4°C / min and clarified and homogenized for 1.5 hours.

[0072] The glass prepared in this embodiment was tested for performance and compared with the comparative example 1. The test results showed that the bubble density was 0.3 / cm 3 , the residual amount of clarifier is reduced by 50%, the strain point of glass is increased by 18℃, the temperature deviation corresponding to 104.5dPa·s is ±1.5℃, and the transmittance is increased by 0.7%.

[0073] Example 3

[0074] The present embodiment provides a method for preparing a composite clarifier system with staged gas release for the production of TFT alkali-free glass substrates, wherein the composite clarifier system comprises a SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier in a mass ratio of 0.5:0.25:0.12:0.3, a nano-scale Sb2O3-loaded Al2O3 dispersion, a CeO2 / SnS2 composite agent, and CaCl2;

[0075] The preparation method of a SiO2 / ZrO2 coated SnO2-CaSO4 core-shell structure clarifier comprises the following steps:

[0076] S1 Preparation of SnO2 sol: Dissolve SnCl2·2H2O in water to prepare a solution with a concentration of 1 mol / L. Slowly add ammonia water dropwise while stirring to adjust the solution pH to 9. Continue stirring for 2 h to form a stable SnO2 sol with a particle size of 20 nm.

[0077] S2 Preparation of CaSO4 precursor solution: Weigh calcium sulfate, add deionized water, heat and stir until completely dissolved, and prepare a CaSO4 solution with a concentration of 0.3 mol / L;

[0078] Formation of S3 core-shell particles: SnO2 sol was added to CaSO4 precursor solution and stirred in a constant temperature water bath at 60°C for 4 hours. During the reaction, CaSO4 gradually deposited on the surface of SnO2 particles to form a precursor of SnO2-CaSO4 core-shell structure;

[0079] Treatment of the S4 coating layer: TEOS and ZrOCl2·8H2O at a molar ratio of 3:1 were added to the above reaction system and reacted under stirring for 2 h to hydrolyze and condense the silicon source and zirconium source to form a SiO2 / ZrO2 coating layer on the surface of the SnO2-CaSO4 core-shell particles;

[0080] S5 washing and drying: After the reaction is completed, the obtained precipitate is washed by centrifugal separation and repeatedly washed with deionized water for 3-5 times until no impurity ions are detected in the washing liquid; the precipitate is then dried in an oven at 100°C for 16 hours to obtain dry SnO2-CaSO4 core-shell particles; finally, SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier with a particle size of D50 = 8 μm is obtained by mechanical grinding and sieving.

[0081] The preparation method of nano-scale Sb2O3-loaded Al2O3 dispersion comprises the following steps:

[0082] (1) Preparation of a porous Al2O3 support: Pseudoboehmite and sesbania powder were uniformly mixed to form a green body, wherein the mass of sesbania powder was 8% of the mass of the pseudoboehmite; the green body was pre-sintered at 600°C for 3 h, then heated to 1300°C and sintered for 6 h to obtain a porous Al2O3 support with a pore size of 6 nm;

[0083] (2) Loading Sb2O3 nanoparticles: Sb2O3 nanoparticles with a particle size of 50 nm were dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 0.1 g / mL. The porous Al2O3 support was immersed in the dispersion and ultrasonically vibrated for 60 min to fully load the Sb2O3 nanoparticles in the pores and on the surface of the porous Al2O3 support.

[0084] (3) Surface treatment and drying: The excess Sb2O3 nanoparticles on the surface were rinsed with anhydrous ethanol and then dried in an oven at 80°C for 12 h to obtain nano-scale Sb2O3-loaded Al2O3 dispersion.

[0085] The preparation method of CeO2 / SnS2 composite agent comprises the following steps:

[0086] 1) Mixed grinding: CeO2 and SnS2 powders were placed in an agate mortar, anhydrous ethanol was added as a grinding aid, and the mixture was fully ground for 60 min to uniformly mix the two powders; the SnS2 powder accounted for 0.1 wt.%;

[0087] 2) Drying treatment: The mixed powder was dried in an oven at 80° C. for 6 h to remove the anhydrous ethanol therein to obtain a CeO 2 / SnS 2 composite.

[0088] When the composite clarifier system of this embodiment is used, the composite clarifier accounts for 1.17 wt.% of the SiO2-Al2O3-B2O3-RO alkali-free glass batch (SiO2 68 wt.%, Al2O3 15 wt.%, B2O3 10 wt.%, RO (MgO 3 wt.%, CaO 2 wt.%, SrO 1 wt.%, BaO 1 wt.%)). When melting the glass, the temperature is first raised from room temperature to 1450°C at a rate of 15°C / min and held for 2 hours; then raised to 1600°C at a rate of 8°C / min and held for 3 hours; finally, the temperature is lowered to 1530°C at a rate of 5°C / min and clarified and homogenized for 2 hours.

[0089] The glass prepared in this embodiment was tested for performance and compared with that in comparative example 1. The test results showed that the bubble density was 0.2 / cm 3 , the residual amount of clarifier is reduced by 55%, the strain point of glass is increased by 19℃, the temperature deviation corresponding to 104.5dPa·s is ±1℃, and the transmittance is increased by 0.8%.

[0090] Comparative Example 1

[0091] The difference from Example 1 is that an equal amount of Sb2O3 is used to replace the composite clarifier system of Example 1.

[0092] The bubble density of the prepared glass was tested to be 10 / cm 3 Compared with Example 1, the residual fining agent content was 1.5 times higher, resulting in crystallization. The strain point of the glass did not significantly increase, with a temperature deviation of ±5°C corresponding to 104.5 dPa·s and a 1.5% loss in transmittance. This is because the traditional single fining agent, Sb2O3, decomposes prematurely during the initial melting of the glass, depleting its active ingredients during the high-temperature phase and preventing sustained fining. Furthermore, it easily forms metallic antimony colloids, affecting transmittance, and residual components induce crystallization.

[0093] Comparative Example 2

[0094] The difference from Example 1 is that the composite clarifier system only includes SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier.

[0095] The bubble density of the prepared glass was tested to be 3 / cm 3 , the clarifier is reduced by 30%, the glass strain point is increased by 10℃, the corresponding temperature deviation of 104.5dPa·s is ±4℃, and the transmittance is increased by 0.3%.

[0096] Compared with Example 1, the performance of the glass prepared in Comparative Example 2 is reduced. This is because the single core-shell structure clarifier has limited clarification effect at different temperature stages and cannot fully utilize the synergistic effect of other components, resulting in the clarification effect and glass performance improvement being inferior to the composite clarifier system in Example 1.

[0097] Comparative Example 3

[0098] The difference from Example 1 is that the SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier is not added to the composite clarifier system.

[0099] After testing, the bubble density of the prepared glass is 5 / cm 3 Compared with Comparative Example 1, the residual amount of clarifier is reduced by 30%, the strain point of the glass is increased by 8°C, the temperature deviation corresponding to 104.5 dPa·s is ±4.5°C, and the transmittance is increased by 0.2%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 3 is reduced. This is because the SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier plays a key role in staged clarification in the entire composite clarifier system. Without this component, it is unable to release gas at the appropriate temperature stage to assist clarification, and cannot provide CaSO4. 2+ As a network modifier, it affects the structure and properties of glass.

[0100] Comparative Example 4

[0101] The difference from Example 1 is that no nano-Sb2O3-loaded Al2O3 dispersion is added to the composite clarifier system.

[0102] The bubble density of the prepared glass was tested to be 4 / cm 3 Compared with Comparative Example 1, the residual clarifier content was reduced by 35%, the glass strain point increased by 12°C, the temperature deviation corresponding to 104.5 dPa·s was ±3.5°C, and the transmittance increased by 0.4%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 4 declined. This is because the nano-Sb2O3-loaded Al2O3 dispersion can increase the oxygen release temperature and continuously release oxygen, promoting the expulsion of bubbles. Therefore, the absence of the nano-Sb2O3-loaded Al2O3 dispersion in Comparative Example 4 would have impaired the clarification effect at low temperatures, affecting the overall clarification efficiency and glass performance.

[0103] Comparative Example 5

[0104] The difference from Example 1 is that no CeO2 / SnS2 composite agent is added to the composite clarifier system.

[0105] The bubble density of the prepared glass was tested to be 3.5 / cm 3Compared with Comparative Example 1, the residual amount of clarifier was reduced by 33%, the strain point of the glass increased by 14°C, the temperature deviation corresponding to 104.5 dPa·s was ±3°C, and the transmittance increased by 0.5%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 5 was reduced. This is because the CeO2 / SnS2 composite can promote gas release and regulate the oxygen partial pressure of the melt at high temperatures. Therefore, the omission of the CeO2 / SnS2 composite in Comparative Example 4 resulted in poor high-temperature clarification, affecting the discharge of bubbles within the glass and the uniformity of the chemical composition, which in turn affected the glass performance.

[0106] Comparative Example 6

[0107] The difference from Example 1 is that in the composite clarifier system, the SnO2-CaSO4 core-shell structure clarifier is not coated with SiO2 / ZrO2.

[0108] The bubble density of the prepared glass was tested to be 6 / cm 3 Compared with Comparative Example 1, the residual amount of clarifier was reduced by 25%, the strain point of the glass increased by 9°C, the temperature deviation corresponding to 104.5 dPa·s was ±4°C, and the transmittance increased by 0.3%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 6 was reduced. This is because the SiO2 / ZrO2 coating delays the decomposition temperature of CaSO4 and provides network-modifying ions at high temperatures. Without this coating, CaSO4 decomposes prematurely and cannot effectively clarify the glass at the critical temperature stage, affecting the clarification effect and structural stability of the glass, thereby reducing the glass performance.

[0109] Comparative Example 7

[0110] The difference from Example 1 is that no CaCl2 is added to the composite clarifier system.

[0111] The bubble density of the prepared glass was tested to be 0.8 / cm 3 Compared with Comparative Example 1, the residual amount was reduced by 41%, the strain point of the glass increased by 15°C, the temperature deviation corresponding to 104.5 dPa·s was ±3°C, and the transmittance increased by 0.4%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 7 was reduced. This is because the lack of CaCl2 cannot effectively remove iron impurities in the glass, resulting in a minimal increase in transmittance and a certain impact on the clarification effect.

Claims

1. A method for preparing a composite clarifier system with phased gas release for the production of TFT alkali-free glass substrates, characterized in that: The composite clarifier system includes a SiO2 / ZrO2 coated SnO2-CaSO4 core-shell structure clarifier, a nano-scale Sb2O3 loaded Al2O3 dispersion, a CeO2 / SnS2 composite agent and CaCl2 in a mass ratio of (0.3-0.5):(0.15-0.25):(0.08-0.12):(0.1-0.3); The preparation method of a SiO2 / ZrO2 coated SnO2-CaSO4 core-shell structure clarifier comprises the following steps: S1 Preparation of SnO2 sol: Prepare SnCl2·2H2O solution, add alkaline solution dropwise under stirring condition, adjust the solution pH to 8-9, and continue stirring to form a stable SnO2 sol; S2 prepares CaSO4 precursor solution; Formation of S3 core-shell particles: Add SnO2 sol to CaSO4 precursor solution and stir in a constant temperature water bath at 50-60℃ for 3-4h to form a SnO2-CaSO4 core-shell structure precursor; Treatment of S4 coating layer: Add silicon source and zirconium source to the above reaction system, react under stirring conditions for 1-2 hours, and form SiO2 / ZrO2 coating layer on the surface of SnO2-CaSO4 core-shell particles; S5 washing and drying: After the reaction is completed, the obtained precipitate is washed, dried, ground and sieved to obtain a SiO2 / ZrO2-coated SnO2-CaSO4 core-shell structure clarifier with a particle size D50 of 5-8 μm; The preparation method of nano-scale Sb2O3-loaded Al2O3 dispersion comprises the following steps: (1) Preparation of a porous Al2O3 carrier: Pseudo-boehmite and additives are uniformly mixed to form a green body, which is pre-sintered at 500-600°C for 2-3 hours and then heated to 1200-1300°C for 4-6 hours to obtain a porous Al2O3 carrier; (2) Loading Sb2O3 nanoparticles: Sb2O3 nanoparticles are dispersed in an organic solvent to prepare a dispersion, and the porous Al2O3 carrier is immersed in the dispersion. Ultrasonic vibration is applied to fully load the Sb2O3 nanoparticles in the pores and on the surface of the porous Al2O3 carrier; (3) Surface treatment and drying: After washing and drying, nano-scale Sb2O3-loaded Al2O3 dispersion is obtained; The preparation method of CeO2 / SnS2 composite agent comprises the following steps: 1) Mixed grinding: Grind CeO2 and SnS2 powders using anhydrous ethanol as a grinding aid to uniformly mix the two powders; 2) Drying treatment: The mixed powder is dried to remove the anhydrous ethanol therein to obtain a CeO2 / SnS2 composite.

2. The method for preparing a composite clarifier system with staged gas release for producing TFT alkali-free glass substrates according to claim 1, wherein: In step S1, the concentration of the SnCl2·2H2O solution is 0.5-1 mol / L; the alkaline solution is ammonia water; and the particle size of the SnO2 sol is 10-20 nm.

3. The method for preparing a composite clarifier system with phased gas release for producing TFT alkali-free glass substrates according to claim 1, wherein: In step S2, the concentration of the CaSO4 precursor solution is 0.2-0.3 mol / L.

4. The method for preparing a composite clarifier system with staged gas release for producing TFT alkali-free glass substrates according to claim 1, wherein: In step S4, the silicon source is tetraethyl orthosilicate, the zirconium source is zirconium oxychloride, and the molar ratio of tetraethyl orthosilicate to zirconium oxychloride is (1-3):

1.

5. The method for preparing a composite clarifier system with staged gas release for producing TFT alkali-free glass substrates according to claim 1, wherein: In step S5, the drying temperature is 80-100° C. and the drying time is 12-16 hours.

6. The method for preparing a composite clarifier system with staged gas release for producing TFT alkali-free glass substrates according to claim 1, wherein: In step (1), the additive is sesbania powder or citric acid, and the mass of the additive is 3-8% of the mass of pseudo-boehmite; the pore size of the porous Al2O3 carrier is 4-6nm.

7. The method for preparing a composite clarifier system with staged gas release for producing TFT alkali-free glass substrates according to claim 1, wherein: In step (2), the particle size of the Sb2O3 nanoparticles is 20-50 nm; the organic solvent is anhydrous ethanol; the concentration of the dispersion is 0.05-0.1 g / mL; the ultrasonic oscillation treatment time is 30-60 min; in step (3), the drying temperature is 60-80°C and the drying time is 8-12 h.

8. The method for preparing a composite clarifier system with staged gas release for producing TFT alkali-free glass substrates according to claim 1, wherein: In step 1), the proportion of SnS2 in the two powders is 0.05-0.1 wt.%; grinding is performed for 30-60 min; in step 2), the drying temperature is 60-80° C., and the drying time is 4-6 h. 9 . A composite clarifier system with phased gas release for the production of TFT alkali-free glass substrates, prepared by the preparation method according to claim 1 .

10. Use of the composite clarifier system with staged gas release for producing TFT alkali-free glass substrates according to claim 9, characterized in that: Add 0.6-1.2wt.% composite clarifier system to the SiO2-Al2O3-B2O3-RO series alkali-free glass batch. When melting the glass, first heat it from room temperature to 1400-1450℃ at a rate of 10-15℃ / min and keep it warm for 1-2h; then heat it to 1550-1600℃ at a rate of 5-8℃ / min and keep it warm for 2-3h; finally cool it to 1500-1530℃ at a rate of 3-5℃ / min and clarify and homogenize it for 1-2h.