Composite clarifying agent system capable of releasing gas in stages for production of TFT alkali-free glass substrate and preparation method and application of composite clarifying agent system

Abstract

The invention discloses a composite clarifying agent system capable of releasing gas in stages for production of a TFT alkali-free glass substrate and a preparation method and application of the composite clarifying agent system. The composite clarifying agent system comprises a SiO2 / ZrO2 coated SnO2-CaSO4 core-shell structure clarifying agent, a nanoscale Sb2O3 loaded Al2O3 dispersion, a CeO2 / SnS2 complexing agent and CaCl2. The bubble density of the prepared TFT alkali-free glass substrate is reduced from conventional 8-12 pieces / cm < 3 > to 0.4 pieces / cm < 3 > or below, the residual quantity of the clarifying agent is reduced by 45-55%, and no stripe or stone defect is observed; the strain point of the glass is increased by 16-19 DEG C, the high-temperature viscosity curve meets the secondary processing requirement of a TFT substrate, the generation of colored ions such as Fe < 2 + > is reduced, the light transmittance is increased by 0.6-0.8%, and the optical performance of the glass is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of glass, 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 clarifiers such as Sb2O3, CaSO4, and SnO2 are widely used to remove bubbles from glass melt to improve the transparency and quality of glass. However, these traditional clarifiers have two key defects in practical applications, which seriously affect the final performance of glass products.

[0003] Defect 1: Early decomposition and insufficient bubble rise rate

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

[0005] Bubble rise is blocked: Because the viscosity of the glass liquid is high (usually greater than 10 2 The high viscosity makes it difficult for bubbles to quickly rise to the liquid surface and escape, thus forming residual bubbles in the glass, affecting the transparency and uniformity of the glass.

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

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

[0008] Residual clarifier and crystallization risk: In order to compensate for the lack of clarification effect in the high temperature stage, the conventional practice is to increase the amount of clarifier. However, this will result in undecomposed clarifier remaining in the glass. These residues may become heterogeneous crystal nuclei, inducing glass crystallization (crystallization rate increases by 0.3-0.5%), thereby reducing the transparency and mechanical strength of the glass.

[0009] Metal antimony colloid formation: In particular, Sb2O3 is easily reduced to metal antimony in a reducing atmosphere to form metal antimony colloid. These colloidal particles will scatter light, causing the transmittance of the glass to lose up to 1.2-1.8%, further affecting the optical properties of the glass.

[0010] In summary, the problems of early decomposition of traditional clarifiers during the glass melting process and insufficient clarification effect at high temperature stages not only affect the transparency and uniformity of the glass, but also bring additional problems such as crystallization and transmittance loss. Therefore, the development of new and efficient clarifiers to overcome these defects 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 and a preparation method and application thereof, wherein the prepared TFT alkali-free glass substrate has a reduced bubble density, a reduced amount of clarifier residue, an increased glass strain point, a high-temperature viscosity curve that meets the requirements of secondary processing of TFT substrates, and reduced Fe 2+ The generation of colored ions such as ions increases the 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 phased 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 invention discloses a method for preparing a SnO2-CaSO4 core-shell structure clarifier coated with SiO2 / ZrO2, wherein the SnO2-CaSO4 core-shell particles are prepared by a sol-gel method, and the decomposition temperature of CaSO4 is delayed from the conventional 1350°C to 1480-1520°C by adjusting the thickness of the SiO2 / ZrO2 coating layer. The coating layer is dissolved by the glass network in the melt at 1550°C, and CaSO4 is released. 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, stir and react 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 for 1-2h under stirring conditions, 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=5-8μm;

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

[0021] (1) Preparing a porous Al2O3 carrier: Pseudo-boehmite and an additive are uniformly mixed to form a green body, the green body is pre-sintered at 500-600°C for 2-3h, and then the temperature is raised to 1200-1300°C and sintered for 4-6h to obtain a porous Al2O3 carrier;

[0022] (2) Loading Sb2O3 nanoparticles: Sb2O3 nanoparticles are dispersed in an organic solvent to prepare a dispersion, and a porous Al2O3 carrier is immersed in the dispersion. Ultrasonic vibration is used 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 Sb2O3 nanoparticles and Al2O3 through surface hydroxyl groups, the initial oxygen release temperature is increased from 900°C to 1300°C, and oxygen release continues to reach 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+ The redox couple can adjust the oxygen partial pressure of the melt (ΔPO2 = 10 -6 -10 -4 atm); specifically including the following steps:

[0025] 1) Mixed grinding: Use anhydrous ethanol as a grinding aid to grind CeO2 and SnS2 powders to make the two powders evenly mixed;

[0026] 2) Drying treatment: Dry the mixed powder 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 aqueous ammonia; 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; 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 0.05-0.1wt.%; grinding is performed for 30-60min; in step 2), the drying temperature is 60-80°C and the drying time is 4-6h.

[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 prepared by the above-mentioned preparation method.

[0035] In the third aspect, the present invention also provides the application of the composite clarifier system with staged gas release for the production of the above-mentioned TFT alkali-free glass substrate. 0.6-1.2wt.% 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 increased from room temperature to 1400-1450℃ at a rate of 10-15℃ / min, and kept warm for 1-2h; then the temperature is increased to 1550-1600℃ at a rate of 5-8℃ / min, and kept warm for 2-3h; finally, the temperature is decreased to 1500-1530℃ at a rate of 3-5℃ / min, and clarified and homogenized for 1-2h.

[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℃), reducing Fe 2+ The generation of colored ions such as ions increases the light transmittance by 0.6-0.8%, further improving the optical properties of the glass. DETAILED DESCRIPTION

[0038] In order to enable persons skilled in the art to better understand the technical solution of the present invention, the technical solution 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 preparation method of the composite clarifier system with staged gas release for the production of TFT alkali-free glass substrates of this embodiment, 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 0.3:0.15:0.08:0.1;

[0041] The preparation method of 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 under 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: Add SnO2 sol to CaSO4 precursor solution and stir in a constant temperature water bath at 50°C for 3 hours. During the reaction, CaSO4 will gradually deposit on the surface of SnO2 particles to form a precursor of SnO2-CaSO4 core-shell structure;

[0045] Treatment of S4 coating layer: TEOS and ZrOCl2·8H2O in a molar ratio of 1:1 were added to the above reaction system, and the mixture was reacted for 1 h under stirring conditions 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=5μm is obtained by mechanical grinding and screening.

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

[0048] (1) Preparing a porous Al2O3 carrier: Pseudo-boehmite and sesbania powder are uniformly mixed to form a green body, wherein the mass of sesbania powder is 3% of the mass of pseudo-boehmite; the green body is pre-sintered at 500°C for 2 h, and then heated to 1200°C and sintered for 4 h to obtain a porous Al2O3 carrier 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 carrier was immersed in the dispersion and subjected to ultrasonic oscillation for 30 min to fully load the Sb2O3 nanoparticles in the pores and on the surface of the porous Al2O3 carrier.

[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: Put CeO2 and SnS2 powders into an agate mortar, add anhydrous ethanol as a grinding aid, and grind them for 30 minutes to make the two powders evenly mixed; the proportion of SnS2 powder is 0.05wt.%;

[0053] 2) Drying treatment: Dry the mixed powder in an oven at 60° C. for 4 h to remove the anhydrous ethanol therein to obtain a CeO2 / SnS2 composite.

[0054] When the composite clarifier system of this embodiment is used, the composite clarifier system accounting for 0.63wt.% of the batch is added to the SiO2-Al2O3-B2O3-RO series alkali-free glass batch (SiO2 68wt.%, Al2O3 15wt.%, B2O3 10wt.%, RO (MgO 3wt.%, CaO 2wt.%, SrO1wt.%, BaO1wt.%). When the glass is melted, the temperature is first raised from room temperature to 1400°C at a rate of 10°C / min and kept warm for 1h; then the temperature is raised to 1550°C at a rate of 5°C / min and kept warm for 2h; finally, the temperature is lowered to 1500°C at a rate of 3°C / min and clarified and homogenized for 1h.

[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 glass strain point is increased by 16°C, the corresponding temperature deviation of 104.5dPa·s is ±2°C, and the transmittance is increased by 0.6%.

[0056] Example 2

[0057] The preparation method of the composite clarifier system with staged gas release for the production of TFT alkali-free glass substrates of this embodiment, 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 0.4:0.2:0.1:0.2;

[0058] The preparation method of 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 under 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 the CaSO4 precursor solution and stirred in a constant temperature water bath at 55°C for 3.5 hours. During the reaction, CaSO4 would gradually deposit on the surface of SnO2 particles to form a precursor of SnO2-CaSO4 core-shell structure.

[0062] Treatment of S4 coating layer: TEOS and ZrOCl2·8H2O in a molar ratio of 2:1 were added to the above reaction system, and the mixture was reacted for 1.5 h under stirring conditions 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 of D50=6.5μm is obtained by mechanical grinding and screening.

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

[0065] (1) Preparing a porous Al2O3 carrier: Pseudo-boehmite and citric acid are uniformly mixed to form a green body, wherein the mass of sesbania powder is 5.5% of the mass of the pseudo-boehmite; the green body is pre-sintered at 550°C for 2.5 hours, and then heated to 1250°C and sintered for 5 hours to obtain a porous Al2O3 carrier 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 carrier was immersed in the dispersion and subjected to ultrasonic oscillation for 45 min to fully load the Sb2O3 nanoparticles in the pores and on the surface of the porous Al2O3 carrier.

[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: Put CeO2 and SnS2 powders into an agate mortar, add anhydrous ethanol as a grinding aid, and grind them for 45 minutes to make the two powders evenly mixed; the proportion of SnS2 powder is 0.075wt.%;

[0070] 2) Drying treatment: Dry the mixed powder in an oven at 70° C. for 5 h to remove the anhydrous ethanol therein to obtain a CeO2 / SnS2 composite.

[0071] When the composite clarifier system of this embodiment is used, the composite clarifier system accounting for 0.9wt.% of the batch is added to the SiO2-Al2O3-B2O3-RO series alkali-free glass batch (SiO2 68wt.%, Al2O3 15wt.%, B2O3 10wt.%, RO (MgO 3wt.%, CaO 2wt.%, SrO1wt.%, BaO1wt.%). When the glass is melted, the temperature is first raised from room temperature to 1425°C at a rate of 12°C / min and kept warm for 1.5h; then the temperature is raised to 1575°C at a rate of 6°C / min and kept warm for 2.5h; finally, the temperature is lowered to 1515°C at a rate of 4°C / min and clarified and homogenized for 1.5h.

[0072] 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 0.3 / 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 preparation method of the composite clarifier system with staged gas release for the production of TFT alkali-free glass substrates of this embodiment, 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 0.5:0.25:0.12:0.3;

[0075] The preparation method of 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 under 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: Add SnO2 sol to CaSO4 precursor solution and stir in a constant temperature water bath at 60°C for 4 hours. During the reaction, CaSO4 will gradually deposit on the surface of SnO2 particles to form a precursor of SnO2-CaSO4 core-shell structure;

[0079] Treatment of S4 coating layer: TEOS and ZrOCl2·8H2O in a molar ratio of 3:1 were added to the above reaction system, and the mixture was reacted for 2 h under stirring conditions 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=8μm is obtained by mechanical grinding and screening.

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

[0082] (1) Preparing a porous Al2O3 carrier: Pseudo-boehmite and sesbania powder are uniformly mixed to form a green body, wherein the mass of sesbania powder is 8% of the mass of pseudo-boehmite; the green body is pre-sintered at 600°C for 3 h, and then heated to 1300°C and sintered for 6 h to obtain a porous Al2O3 carrier 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 carrier was immersed in the dispersion and subjected to ultrasonic oscillation for 60 min to fully load the Sb2O3 nanoparticles in the pores and on the surface of the porous Al2O3 carrier.

[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: Put CeO2 and SnS2 powders into an agate mortar, add anhydrous ethanol as a grinding aid, and grind them for 60 minutes to make the two powders evenly mixed; the proportion of SnS2 powder is 0.1wt.%;

[0087] 2) Drying treatment: Dry the mixed powder in an oven at 80° C. for 6 h to remove the anhydrous ethanol therein to obtain a CeO2 / SnS2 composite.

[0088] When the composite clarifier system of this embodiment is used, the composite clarifier accounts for 1.17wt.% of the SiO2-Al2O3-B2O3-RO series alkali-free glass batch (SiO2 68wt.%, Al2O3 15wt.%, B2O3 10wt.%, RO (MgO 3wt.%, CaO 2wt.%, SrO1wt.%, BaO1wt.%). When the glass is melted, the temperature is first increased from room temperature to 1450°C at a rate of 15°C / min and kept warm for 2h; then the temperature is increased to 1600°C at a rate of 8°C / min and kept warm for 3h; finally, the temperature is decreased to 1530°C at a rate of 5°C / min and clarified and homogenized for 2h.

[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 glass strain point is increased by 19°C, the corresponding temperature deviation of 104.5dPa·s is ±1°C, and the transmittance is increased by 0.8%.

[0090] Comparative Example 1

[0091] The difference from Example 1 is that Sb2O3 is used in an equal amount 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 amount of clarifier is 1.5 times higher, crystallization occurs, the glass strain point does not increase significantly, the temperature deviation corresponding to 104.5 dPa·s is ±5°C, and the transmittance loss is 1.5%. This is because the traditional single clarifier Sb2O3 will decompose prematurely in the early stage of glass melting, resulting in the exhaustion of effective components in the high temperature stage, and the inability to continue to clarify. It is easy to generate metal antimony colloid, which affects the transmittance, and the 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°C, the temperature deviation corresponding to 104.5dPa·s is ±4°C, 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 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 impossible to release gas at the appropriate temperature stage to assist clarification, and it is impossible to provide CaSO4. 2+ As a network modifier, it affects the glass structure and properties.

[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 amount of clarifier is reduced by 35%, the strain point of glass is increased by 12°C, the temperature deviation corresponding to 104.5 dPa·s is ±3.5°C, and the transmittance is increased by 0.4%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 4 is reduced. This is because the nano-Sb2O3 loaded Al2O3 dispersion can increase the oxygen release temperature and continuously release oxygen, and promote the discharge of bubbles. Therefore, in Comparative Example 4, no nano-Sb2O3 loaded Al2O3 dispersion is added, which will make the clarification effect at the low temperature stage worse, 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 is reduced by 33%, the strain point of glass is increased by 14°C, the temperature deviation corresponding to 104.5dPa·s is ±3°C, and the transmittance is increased by 0.5%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 5 is reduced. This is because the CeO2 / SnS2 composite can promote gas release and adjust the oxygen partial pressure of the melt at high temperature. Therefore, the CeO2 / SnS2 composite is not added in Comparative Example 4, which will lead to poor high-temperature clarification effect, affect the discharge of bubbles inside the glass and the uniformity of the chemical composition, and thus affect the performance of the glass.

[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 6 / cm 3 Compared with Comparative Example 1, the residual amount of clarifier is reduced by 25%, the strain point of glass is increased by 9°C, the temperature deviation corresponding to 104.5 dPa·s is ±4°C, and the transmittance is increased by 0.3%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 6 is reduced. This is because the SiO2 / ZrO2 coating layer can delay the decomposition temperature of CaSO4 and provide network modification ions at high temperatures. Without this coating layer, CaSO4 decomposes prematurely and cannot play an effective clarification role at the critical temperature stage, which affects the clarification effect and structural stability of the glass and reduces the performance of the glass.

[0109] Comparative Example 7

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

[0111] The test showed that the bubble density of the prepared glass was 0.8 / cm 3 Compared with Comparative Example 1, the residual amount is reduced by 41%, the strain point of the glass is increased by 15°C, the temperature deviation corresponding to 104.5 dPa·s is ±3°C, and the transmittance is increased by 0.4%. However, compared with Example 1, the performance of the glass prepared in Comparative Example 7 is reduced. This is because the lack of CaCl2 cannot effectively remove iron impurities in the glass, resulting in an insignificant 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 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, stir and react 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 for 1-2h under stirring conditions, 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=5-8μm; The preparation method of nano-scale Sb2O3 loaded Al2O3 dispersion comprises the following steps: (1) Preparing a porous Al2O3 carrier: Pseudo-boehmite and an additive are uniformly mixed to form a green body, the green body is pre-sintered at 500-600°C for 2-3h, and then the temperature is raised to 1200-1300°C and sintered for 4-6h to obtain a porous Al2O3 carrier; (2) Loading Sb2O3 nanoparticles: Sb2O3 nanoparticles are dispersed in an organic solvent to prepare a dispersion, and a porous Al2O3 carrier is immersed in the dispersion. Ultrasonic vibration is used 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: Use anhydrous ethanol as a grinding aid to grind CeO2 and SnS2 powders to make the two powders evenly mixed; 2) Drying treatment: Dry the mixed powder to remove the anhydrous ethanol therein to obtain a CeO2 / SnS2 composite.

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

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

4. The method for preparing the composite clarifier system with phased gas release for producing TFT alkali-free glass substrate according to claim 1, characterized in that: 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 the composite clarifier system with phased gas release for producing TFT alkali-free glass substrate according to claim 1, characterized in that: In step S5, the drying temperature is 80-100° C. and the drying time is 12-16 hours.

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

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

10. The use of the composite clarifier system with phased 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.