Alkali-free aluminoborosilicate glass composite clarifying agent and clarifying method thereof

Abstract

The invention relates to the technical field of glass, in particular to an alkali-free aluminoborosilicate glass composite clarifying agent and a clarifying method thereof. The alkali-free aluminoborosilicate glass composite clarifying agent is prepared from the following raw materials in percentage by mass on the basis of the total mass of alkali-free aluminoborosilicate glass: 0.4 to 5.5 percent of halogen alkaline earth metal salt, 0.03 to 0.4 percent of lanthanum oxide, 0.01 to 0.4 percent of tin dioxide and 0.01 to 0.3 percent of cerium dioxide. The alkali-free aluminoborosilicate glass composite clarifying agent is applied to alkali-free aluminoborosilicate glass, and the problems that the alkali-free aluminoborosilicate glass is poor in clarifying effect and has many bubble defects are solved; the corrosion of high-temperature molten glass to refractory materials at parts such as a tank furnace and the like is reduced, so that the number of stone defects of the refractory materials in the glass is reduced, and the service life of the refractory materials of the furnace is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of glass, and particularly to a non-alkali aluminoborosilicate glass composite fining agent and a fining method thereof. Background Art

[0002] The manufacturing process of glass substrates used in liquid crystal displays such as active matrix liquid crystal displays (AMLCDs) requires multiple steps including high-temperature melting, fining, homogenization, cooling, forming, and cutting of various batch materials. Errors in the glass melting process, process settings, and operation procedures will cause various defects. The existence of glass defects will seriously reduce the quality of the glass and even affect the further processing of the glass. Glass defects can be divided into two categories, namely internal defects and external defects. Gas inclusions in internal defects are due to the fact that during high-temperature melting, various batch materials will bring in air, and the reaction products released by the physical and chemical reactions of raw materials such as nitrates and carbonates after high-temperature decomposition and melting are not only inevitable products in glass production but also redundant products outside the glass structure, which are called gaseous inclusions, also known as "bubbles". The existence of a large number of "bubbles" in the glass will affect the uniformity, light transmittance, mechanical strength, and thermal stability of the glass, and ultimately have a fatal impact on the glass product.

[0003] In addition, non-alkali aluminoborosilicate glass used as a display panel has a high glass melting temperature, high high-temperature viscosity, and is difficult to melt and fine during the formation process, resulting in defects such as bubbles and streaks due to uneven heating inside the glass melt. At the same time, it will consume more energy and reduce the service life of thermal equipment. In order to reduce the generation of "bubbles" in non-alkali glass, it is necessary to use an effective fining agent to generate gas. On the one hand, it expels the gas generated by the reaction of glass components, and on the other hand, during high-temperature fining and homogenization, it increases the volume of bubbles, combines multiple small bubbles into a large bubble, floats on the surface of the glass liquid, and then breaks and disappears to discharge tiny bubbles, thus obtaining bubble-free and high-quality glass.

[0004] According to different glass batch formulas and production processes, the bubbles in the glass have the characteristics of chemical and structural diversity. According to the size, there are gray bubbles (diameter less than 0.8 mm) and bubbles (diameter greater than 0.8 mm); according to the chemical composition, there are O 2 、N 2 、CO、CO 2 、SO 2, nitrogen oxides, water vapor, etc. According to the different causes of bubble generation, there are primary bubbles, secondary bubbles, external air bubbles, refractory material bubbles, etc. Using clarifying agents to eliminate bubbles in glass and make the glass clear is one of the most common methods. Clarifying agents are important auxiliary raw materials in the glass production process. During the glass melting process, they can generate gases through high-temperature decomposition (vaporization) or reduce the viscosity of the glass melt, promoting the elimination of bubbles in the glass melt. According to the clarification mechanism, clarifying agents are divided into four categories: oxide clarifying agents, sulfate clarifying agents, halide clarifying agents, and composite clarifying agents. Common clarifying agents include arsenic oxide, antimony oxide, fluorides, tin oxide, nitrates, rare earth compounds, etc. Among them, arsenic oxide and antimony oxide have excellent clarification effects, but due to the high toxicity of arsenic and antimony-based clarifying agents, they bring a great burden to the economy and the environment. Therefore, in order to develop clarifying agents with better clarification effects or even higher than those of arsenic and antimony-based clarifying agents, extensive research has been carried out on composite clarifying agents. A composite clarifying agent is a combination of several clarifying agents, and a composite high-efficiency clarifying agent is prepared by mixing them in a certain proportion. The composite clarifying agent can generate various gases different from the bubbles in the melt at different stages of the melt, not only solving the problem of single gas phase but also achieving the effect of synergistic clarification. It can release multiple gases within a relatively wide temperature range, enabling the bubbles to be quickly discharged, and having a better clarification effect than a single clarifying agent. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite clarifying agent for non-alkali aluminoborosilicate glass, which is used to solve the problems of poor clarification effect and many bubble defects of the composite clarifying agent for non-alkali aluminoborosilicate glass in the prior art.

[0006] The present invention also provides a clarification method for a composite clarifying agent for non-alkali aluminoborosilicate glass, which is used to solve the problems of poor clarification effect and many bubble defects of the composite clarifying agent for non-alkali aluminoborosilicate glass in the prior art.

[0007] In order to solve the above problems, the present invention proposes a composite clarifying agent for non-alkali aluminoborosilicate glass. The technical solution adopted is: a composite clarifying agent for non-alkali aluminoborosilicate glass, based on the total mass of the non-alkali aluminoborosilicate glass, calculated by mass percentage, the raw materials of the composite clarifying agent for non-alkali aluminoborosilicate glass include: 0.4% - 5.5% of halogen alkaline earth metal salt, 0.03% - 0.4% of lanthanum oxide, 0.01% - 0.4% of tin dioxide, and 0.01% - 0.3% of cerium dioxide.

[0008] The beneficial effects of the present invention are as follows: By adding tin dioxide and alkaline earth metal halide salts, the combination of the two can generate an intermediate product, tin halide. At high temperatures (1200°C - 1400°C), the volatiles generated diffuse from the glass melt into the remaining bubbles, causing them to expand, rise, and escape, reducing the generation of bubbles and contributing to the clarification and homogenization of the glass melt. In addition, at high temperatures, tin halide can decompose into tin oxide, releasing halides, effectively increasing the bubble discharge temperature and preventing tin oxide from being reduced by H 2 in the tin bath, which can cause defects on the air surface of the glass. It can also reduce the viscosity, softening point, and surface tension of the glass melt, accelerating the clarification and homogenization rate of the glass melt.

[0009] Both cerium dioxide and tin dioxide added in the present invention belong to high-temperature fining agents, and their decomposition temperatures are higher than 1400°C. And tin dioxide loses oxygen to form SnO at temperatures above 1400°C, releasing oxygen, which can reduce the decomposition of cerium dioxide in the initial melting stage, thus ensuring the amount of oxygen required for clarification, enabling other small bubbles in the glass to penetrate into the oxygen bubbles to achieve rapid clarification, and reducing the generation of ash bubbles.

[0010] By adding lanthanum oxide and alkaline earth metal halide salts, the combination of the two can effectively inhibit the coloring effect of cerium dioxide. In the glass melting stage, the solid solution formed by lanthanum ions (La 3+ ) and the alkaline earth metal halide salt exists in the glass melt as an intermediate product, which can absorb small bubbles and release large bubbles, effectively reducing the content of microbubbles in the glass melt. In addition, the combination of the alkaline earth metal halide salt and lanthanum oxide can improve the optical properties of the glass, endowing the glass with some properties of ultra-clear glass, with less absorption of visible light, increasing the transmittance and refractive index.

[0011] By adding lanthanum oxide and tin dioxide, they react with the alkaline earth metal halide salt at high temperatures. The alkaline earth metal halide salt halogenates lanthanum oxide and tin dioxide to form intermediate substances such as halogen oxides. These intermediate substances will not cause erosion damage to the refractory material, avoiding corrosion caused by the reaction of halides with the refractory material, solving the erosion of halides to the refractory material, and extending the service life of the kiln. At the same time, lanthanum oxide can increase the elastic modulus of the glass, reduce the high-temperature viscosity, and is beneficial to improving the glass strength.

[0012] The non-alkali aluminoborosilicate glass composite fining agent of the present invention has the following advantages: 1. Through the design of the mass ratios of alkaline earth metal halide salts, lanthanum oxide, tin dioxide, and cerium dioxide, different gases are released at different temperature intervals in the present invention, enabling continuous clarification in different temperature ranges. Moreover, the halide in this composite fining agent reduces the viscosity of the glass melt, comprehensively reducing the bubbles in the glass melt, solving the problems of poor clarification effect and numerous bubble defects in alkali-free aluminoborosilicate glass. Additionally, by reducing the high-temperature viscosity of alkali-free aluminoborosilicate glass, the melting temperature is decreased, reducing the erosion of refractory materials in parts such as the tank furnace by the high-temperature glass melt, thereby reducing the number of refractory inclusions defects in the glass and simultaneously extending the service life of the kiln refractory materials.

[0013] 2. When using this composite fining agent, through the high-temperature volatilization and decomposition of alkaline earth metal halide salts, the fining ability of common single fining agents such as tin oxide and cerium dioxide is significantly increased, reducing the content of bubbles in the glass, and simultaneously preventing the coloring of the glass.

[0014] 3. By using this composite fining agent, the high-temperature viscosity and melting temperature of the glass melt can be effectively reduced, thereby reducing the erosion of the refractory materials by the glass, reducing the generation of inclusions, improving the product quality, and simultaneously reducing the production cost.

[0015] 4. The composite fining agent designed in the present invention completely avoids using toxic substances arsenic oxide and antimony oxide, and belongs to an environmentally friendly composite fining agent.

[0016] In order to further reduce the bubble defects in the glass melt and improve the clarification effect of alkali-free aluminoborosilicate glass, preferably, based on the total mass of the alkali-free aluminoborosilicate glass, by mass percentage, the raw materials of the alkali-free aluminoborosilicate glass composite fining agent include: alkaline earth metal halide salts 0.8% - 5.5%, lanthanum oxide 0.13% - 0.4%, tin dioxide 0.01% - 0.22%, and cerium dioxide 0.1% - 0.3%. When the obtained alkali-free aluminoborosilicate glass composite fining agent is applied in alkali-free aluminoborosilicate glass, the number of bubbles (0.05mm < bubble diameter d < 1mm) is less than 9.

[0017] In order to further reduce the bubble defects in the glass melt, improve the clarification effect of alkali-free aluminoborosilicate glass, and simultaneously reduce the melting temperature of alkali-free aluminoborosilicate glass, preferably, based on the total mass of the alkali-free aluminoborosilicate glass, by mass percentage, the raw materials of the alkali-free aluminoborosilicate glass composite fining agent include: alkaline earth metal halide salts 1.8% - 5.5%, lanthanum oxide 0.13% - 0.18%, tin dioxide 0.17% - 0.22%, and cerium dioxide 0.1% - 0.3%. When the obtained alkali-free aluminoborosilicate glass composite fining agent is applied in alkali-free aluminoborosilicate glass, the number of bubbles (0.05mm < bubble diameter d < 1mm) is less than 9, and at the same time, the melting temperature T of the alkali aluminoborosilicate glass 200 pReduce to below 1623 °C.

[0018] In order to enable the halogen vapor to diffuse from the glass melt into the remaining bubbles, causing them to expand, rise, and escape, thereby improving the clarification and homogenization effects of the glass melt, preferably, the alkaline earth metal halide salt is one or more of sodium chloride, strontium chloride, and calcium chloride.

[0019] In order to further reduce the viscosity, softening point, and surface tension of the glass melt, and improve the clarification and homogenization effects of the glass melt, preferably, the alkaline earth metal halide salt includes sodium chloride, strontium chloride, and calcium chloride, and the mass ratio of sodium chloride, strontium chloride, and calcium chloride is (0.15 - 2.2):(0.15 - 3.4):(0.1 - 1.6).

[0020] In order to efficiently increase the contact area between particles, facilitate melting and reaction in the glass melt, and fully exert the clarification effect, preferably, the particle size of the alkaline earth metal halide salt is less than 400 μm, the particle size of lanthanum oxide is less than 12 μm, the particle size of tin dioxide is less than 90 μm, and the particle size of cerium dioxide is less than 10 μm.

[0021] In order to further increase the contact area between particles, accelerate melting and reaction in the glass melt, and improve the clarification effect, preferably, the particle size of the alkaline earth metal halide salt is 45 - 350 μm, the particle size of lanthanum oxide is 1 - 10 μm, the particle size of tin dioxide is 20 - 85 μm, and the particle size of cerium dioxide is 3 - 8 μm.

[0022] The present invention also proposes a clarification method for a non-alkali aluminoborosilicate glass composite fining agent, and the technical solution adopted is as follows: A clarification method for a non-alkali aluminoborosilicate glass composite fining agent, comprising the following steps: successively mixing, melting, clarifying, forming, and annealing the raw materials of the above-mentioned non-alkali aluminoborosilicate glass composite fining agent and glass raw materials to obtain non-alkali aluminoborosilicate glass; wherein, based on the total mass of the non-alkali aluminoborosilicate glass, the glass raw materials, by mass percentage, include: SiO 2 55% - 70%, Al 2 O 3 15% - 18%, B 2 O 3 1% - 8%, MgO 2% - 4%, CaO 3% - 5%, SrO 1% - 4%, and BaO 3% - 8%; the mass of the non-alkali aluminoborosilicate glass composite fining agent is 0.5% - 6% of the total mass of the non-alkali aluminoborosilicate glass.

[0023] The beneficial effects of the present invention are as follows: The fining of the non-alkali aluminoborosilicate glass is carried out by using the non-alkali aluminoborosilicate glass composite fining agent, and then the non-alkali aluminoborosilicate glass is obtained, which solves the problems of poor fining effect and many bubble defects of the non-alkali aluminoborosilicate glass. Moreover, by reducing the high-temperature viscosity of the non-alkali aluminoborosilicate glass, the melting temperature is reduced, the erosion of refractory materials such as the tank furnace by the high-temperature glass liquid is reduced, and at the same time, the service life of the refractory materials of the kiln is extended.

[0024] Specifically, SiO 2 is the most important participant in the three-dimensional network structure of the non-alkali aluminoborosilicate system glass. Si 4+ is connected to 4 O 2- to form a [SiO 4 structure. As a network former, SiO 2 can improve the thermal stability, chemical resistance and mechanical strength of the glass, and at the same time can reduce the thermal expansion coefficient and density of the glass. When the content is too high, the strain point will be increased, but the high-temperature viscosity will be increased, the fusibility will be reduced, devitrification crystals such as cristobalite will precipitate, and the liquidus temperature will rise; when the content is too low, it is not conducive to enhancing the chemical resistance, and the expansion coefficient will be too high and the strain point will be too low, resulting in easy devitrification of the glass. Therefore, the mass percentage content of SiO 2 is 55% - 70%.

[0025] A1 2 O 3 As an intermediate oxide, Al 3+ has various possible coordination states such as [AlO 6 and [AlO 4 . When there is sufficient free oxygen, Al 3+ can form a 4-coordinate aluminum oxygen tetrahedron [AlO 4 , which is connected to [SiO 4 to strengthen the network structure of the glass, and then form an aluminum oxygen octahedron [AlO 6 , acting as a network modifier and located in the pores of the silicon oxygen network. A1 2 O 3 As another glass former, it can improve the strain point, Young's modulus, thermal stability, chemical resistance and mechanical strength of the glass, and at the same time can reduce the crystallization tendency and thermal expansion coefficient of the glass. When the content is too much, the melting of the batch and the fining difficulty of the glass increase, and the liquidus temperature is easy to rise and devitrification crystals such as mullite and anorthite are easy to precipitate; when the content is too low, the strain point and Young's modulus are easy to decrease, and the glass is easy to phase separate. Therefore, the mass percentage content of A1 2 O 3 is 15% - 18%.

[0026] B 2 O 3It is a participant in the glass network and acts more as a provider of free oxygen in the network gap. Under high temperature melting conditions, B 2 O 3 So [BO 3 ] It can reduce high temperature viscosity and capture free oxygen at low temperature to form [BO 4 ], making the structure compact, improving the low-temperature viscosity of the glass and preventing crystallization. 2 O 3 As a co-solvent, it can improve the solubility, high temperature viscosity, expansion coefficient and liquidus temperature of glass. When the content is too high, it will cause the strain point to drop (B 2 O 3 When the concentration is greater than 7.0 mol%, the temperature drops by about 10°C for every 1 mol% increase), the modulus and chemical resistance also decrease; when the content is too low, the melting property and devitrification resistance are easily reduced. Therefore, B 2 O 3 The mass percentage content is 1% to 8%.

[0027] MgO, as a network external oxide, reduces the high temperature viscosity of glass without reducing the strain point, makes the glass easy to melt, and improves solubility. Compared with other alkaline earth metals, MgO is an effective component for increasing Young's modulus without increasing glass density and thermal expansion coefficient. However, when the content is too high, the glass structure becomes loose, the density and hardness decrease, the chemical resistance decreases, and the liquidus temperature increases; when the content is too low, the solubility and Young's modulus are easy to decrease. Therefore, the mass percentage content of MgO is 2% to 4%.

[0028] Among alkaline earth metal oxides, CaO mainly produces low liquidus temperature, high strain point and high modulus, improves chemical resistance and reduces high temperature viscosity, and is a relatively cheap batch material. However, if the CaO content is too high, the glass will become easy to devitrify (crystallize), and the thermal expansion coefficient will increase significantly; if the content is too low, it is impossible to achieve a high strain point and high Young's modulus. Therefore, the mass percentage of CaO is 3% to 5%.

[0029] In alkali-free glass, both SrO and BaO play a role in lowering the liquidus temperature, and usually contain at least one of these oxides. Compared with MgO and CaO, both SrO and BaO increase CTE and density, and reduce modulus and strain point. Since Ba and Sr elements are heavy metals with large relative molecular mass, excessive introduction will increase the density of glass, which is not conducive to the lightweight development of substrate glass. Therefore, the mass percentage of SrO is 1% to 4%, and the mass percentage of BaO is 3% to 8%.

[0030] The alkali-free aluminoborosilicate glass clarified by the above compound clarifying agent is applied to various liquid crystal displays, preferably as the substrate glass substrate material for preparing flat display products and / or the substrate glass substrate material for flexible display products.

[0031] In order to further improve the clarification effect of the alkali-free aluminoborosilicate glass and reduce bubble defects, preferably, the mass of the alkali-free aluminoborosilicate glass compound clarifying agent is 1.4% - 6% of the total mass of the alkali-free aluminoborosilicate glass.

[0032] In order to make each component fully melt, preferably, the melting temperature is 1300 - 1680 °C and the time is 2 - 12 h. Detailed implementation mode

[0033] In the prior art, the clarification effect of the alkali-free aluminoborosilicate glass compound clarifying agent is poor and there are many bubble defects. The present invention proposes an alkali-free aluminoborosilicate glass compound clarifying agent. Based on the total mass of the alkali-free aluminoborosilicate glass, by mass percentage, the raw materials of the alkali-free aluminoborosilicate glass compound clarifying agent include: 0.4% - 5.5% of alkaline earth metal halide salt, 0.03% - 0.4% of lanthanum oxide, 0.01% - 0.4% of tin dioxide, and 0.01% - 0.3% of cerium dioxide.

[0034] The technical concept of the present invention is: in the alkali-free aluminoborosilicate glass compound clarifying agent, the role of the alkaline earth metal halide salt: the alkaline earth metal halide salt can generate halogen vapor at 1200 - 1400 °C and diffuse from the glass melt into the remaining bubbles, causing them to expand, rise and escape, playing a clarification and homogenization effect in the glass melt. In addition, the alkaline earth metal halide salt can reduce the viscosity, softening point and surface tension of the glass melt at high temperature, which is more conducive to the discharge and homogenization of bubbles in the glass melt.

[0035] The role of lanthanum oxide: lanthanum oxide is mainly used to clarify bubbles with a diameter less than 0.5 mm in the glass, and it has a relatively high oxidation potential, so the clarification effect is better than other traditional clarifying agents. Due to its low volatility, lanthanum oxide can reduce dust and waste gas losses in actual production such as the float process and the overflow process, saving production costs; at the same time, lanthanum oxide can improve the chemical stability and lifespan of the glass and reduce the thermal expansion coefficient.

[0036] The role of tin dioxide: at a melting temperature above 1500 °C, tin dioxide precipitates stannous oxide, that is: SnO 2 →SnO + O 2 , and the precipitated oxygen diffuses into the glass melt network to form large bubbles and escape, thereby reducing the gas in the glass to improve the clarification effect of the glass.

[0037] Function of cerium dioxide: Cerium oxide acts as a fining agent during the glass melting process. At a temperature of 1300°C - 1400°C, it undergoes a decomposition reaction to release oxygen, i.e., CeO 2 → Ce 2 O 3 +O 2 , and the precipitated oxygen can diffuse and penetrate into the bubbles in the glass melt to make them larger, thereby promoting the escape of bubbles from the glass melt. At the same time, the oxygen released by the decomposition of cerium oxide can oxidize Fe 2+ with strong coloring ability in the glass into Fe 3+ with weak coloring ability, thus making the glass nearly colorless and increasing the light transmittance.

[0038] Specifically, the fining method of the alkali-free aluminoborosilicate glass composite fining agent includes the following steps: First, weigh the following proportions of glass raw materials, i.e., SiO 2 55% - 70%, Al 2 O 3 15% - 18%, B 2 O 3 1% - 8%, MgO 2% - 4%, CaO 3% - 5%, SrO 1% - 4% and BaO 3% - 8%; Then, add the raw materials of the alkali-free aluminoborosilicate glass composite fining agent to the above glass raw materials. Among them, the mass of the added alkali-free aluminoborosilicate glass composite fining agent is 0.5 - 6% of the total mass of the alkali-free aluminoborosilicate glass; Next, put the above glass raw materials and the raw materials of the alkali-free aluminoborosilicate glass composite fining agent into a mixer and mix for 20 - 40 min to obtain a glass mixture; Then, melt the glass mixture at a high temperature of 1300 - 1680°C for 2 - 12 h, and then carry out fining and forming; Finally, anneal the formed glass in a high-temperature annealing furnace at about 800°C for 2 h, and cool it with the furnace to obtain the alkali-free aluminoborosilicate glass.

[0039] Preferably, the particle size of the halogen alkaline earth metal salt is less than 400μm, the particle size of lanthanum oxide is less than 12μm, the particle size of tin dioxide is less than 90μm, and the particle size of cerium dioxide is less than 10μm.

[0040] The following combines specific embodiments to elaborate in detail on the implementation process of the present invention.

[0041] In the following examples and comparative examples, the particle size of the halogen alkaline earth metal salt in the raw materials used is 45-350 μm, the particle size of lanthanum oxide is 1-10 μm, the particle size of tin dioxide is 20-85 μm, and the particle size of cerium dioxide is 3-8 μm; the remaining raw materials are all ordinary commercially available products that can be directly purchased or can be prepared according to the conventional techniques in the art.

[0042] I. Examples of the clarification method of the non-alkali aluminoborosilicate glass composite clarifier of the present invention Examples 1-11 Examples 1-11 all provide a clarification method for a non-alkali aluminoborosilicate glass composite clarifier, including the following steps: First, according to the component ratios in Table 1, calculate and weigh the corresponding raw materials for each component, and put the raw materials of each component into a mixer for 30 min of mixing to obtain a glass mixture; secondly, put the glass mixture into a platinum crucible, and melt the mixed materials in a high-temperature lifting furnace to obtain a glass melt, wherein the melting temperature is 1680 °C and the time is 8 h; then, pour the glass melt into a preheated stainless steel mold for forming; finally, wait for the glass to be formed and demolded, put it into a high-temperature annealing furnace at 800 °C for annealing for 2 h, and cool down with the furnace to obtain a non-alkali aluminoborosilicate glass.

[0043] In this application, when the melting treatment temperature is 1300 °C and the time is 2 h, the non-alkali aluminoborosilicate glass obtained by clarification has the same technical effect as the above examples.

[0044] In this application, when the halogen alkaline earth metal salt is one or any two of sodium chloride, strontium chloride, and calcium chloride, the non-alkali aluminoborosilicate glass obtained by clarification has the same technical effect as the above examples.

[0045] Table 1 Component ratios of non-alkali aluminoborosilicate glass in Examples 1-11

[0046] II. Comparative examples Comparative examples 1-3 Comparative examples 1-3 all provide a clarification method for a non-alkali aluminoborosilicate glass composite clarifier, including the following steps: First, according to the mixing ratios of each group in Table 2, calculate and weigh the corresponding raw materials for each component. Put the raw materials of each component into a mixer and mix them for 30 minutes to obtain a glass mixture. Secondly, put the glass mixture into a platinum crucible and melt the mixed materials in a high-temperature lift furnace to obtain glass liquid. Among them, the melting temperature is 1680 °C and the time is 8 hours. Then, pour the glass liquid into a preheated stainless steel mold for forming. Finally, wait for the glass to be formed and demolded, put it into a high-temperature annealing furnace at 800 °C for annealing for 2 hours, and cool it with the furnace to obtain an alkali-free aluminoborosilicate glass.

[0047] Table 2 Mixing ratios of each component of the alkali-free aluminoborosilicate glass in Comparative Examples 1-3

[0048] III. Experimental Examples Cut the alkali-free aluminoborosilicate glass clarified in the above-mentioned examples and comparative examples with a wire cutting machine into sliced glass samples with a thickness of 0.3 mm. Then, grind and polish the slices for finishing. Finally, conduct physical and chemical property tests on the sliced samples of the alkali-free aluminoborosilicate glass in Examples 1-11 and Comparative Examples 1-3 respectively.

[0049] Specifically, the density of the alkali-free aluminoborosilicate glass is measured according to the Archimedes method; the Young's modulus is measured by the bending resonance method; the coefficient of thermal expansion (50 °C - 300 °C) is measured with a German DIL-402PC horizontal dilatometer, and the heating rate is 5 °C / min; the Vickers hardness is measured with a Vickers hardness tester according to the standard ASTM E-384; the strain point temperature, annealing point temperature, and softening point temperature are measured with reference to the standards ASTM C-336 and ASTM C-338; the melting temperature (T 200 p ) is first measured by a high-temperature viscometer to measure the viscosity, and then the melting temperature is calculated by the Vogel-Fulcher-Tamann formula; Test method for the number of bubbles in the glass: irradiate the sliced glass sample with a halogen lamp, use a scale magnifying ruler to determine its size, count the number of bubbles, and use a German Leica polarizing microscope to count the number of bubbles with 0.05 mm < bubble diameter < 0.1 mm. The specific test results are shown in Tables 3 and 4: Table 3 Test results of the properties of the alkali-free aluminoborosilicate glass clarified in Examples 1-11

[0050] Table 4 Test results of the properties of the alkali-free aluminoborosilicate glass clarified in Comparative Examples 1-3

[0051] As can be seen from Table 3 and Table 4, the density of the alkali-free aluminoborosilicate glass obtained by clarification in Examples 1-11 of this application is 2.376-2.691 g / cm 3 ; the coefficient of thermal expansion is 28.8-31.5×10 -7 / °C; the Young's modulus is 75.3-79.5 GPa; the Vickers hardness is 649-673 GPa; the strain point is 745-775°C; the annealing point is 762-802°C; the softening point is 885-920°C; the melting temperature T 200p is below 1635°C, with a minimum of 1613°C; the number of bubbles with 0.05 mm < bubble diameter d < 1 mm is less than 15, with a minimum of 2.

[0052] However, in the composition of the alkali-free aluminoborosilicate glass composite fining agent of Comparative Example 1, no alkaline earth metal halide, La 2 O 3 and CeO 2 were added. In the composition of the alkali-free aluminoborosilicate glass composite fining agent of Comparative Example 2, no alkaline earth metal halide, La 2 O 3 and SnO 2 were added. In the composition of the alkali-free aluminoborosilicate glass composite fining agent of Comparative Example 3, alkaline earth metal halide and La 2 O 3 were added. The melting temperature T 200 p of the alkali-free aluminoborosilicate glass obtained by clarification in Comparative Examples 1-3 is above 1642°C, with a maximum of 1662°C; the number of bubbles with 0.05 mm < bubble diameter d < 1 mm is more than 28, with a maximum of 54.

[0053] This shows that the alkali-free aluminoborosilicate glass composite fining agent provided by this application is applied to alkali-free aluminoborosilicate glass, releases different gases at different temperature intervals, and reduces the viscosity of the glass melt through the halide in the composite fining agent, comprehensively reducing the bubbles in the glass melt, solving the problems of poor clarification effect and many bubble defects of alkali-free aluminoborosilicate glass. Moreover, by reducing the high-temperature viscosity of alkali-free aluminoborosilicate glass, the melting temperature is reduced, the erosion of refractory materials in parts such as the tank furnace by the high-temperature glass melt is reduced, and thus the number of refractory material nodules defects in the glass is reduced, and at the same time, the service life of the kiln refractory materials is extended.

[0054] The above is only the preferred embodiment of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An alkali-free aluminoborosilicate glass composite clarifier, characterized in that: Based on the total mass of the alkali-free aluminoborosilicate glass, the raw materials of the alkali-free aluminoborosilicate glass composite clarifier include, by mass percentage, 0.4% to 5.5% of halogen alkaline earth metal salt, 0.03% to 0.4% of lanthanum oxide, 0.01% to 0.4% of tin dioxide and 0.01% to 0.3% of cerium dioxide.

2. The alkali-free aluminoborosilicate glass composite clarifier according to claim 1, characterized in that: Based on the total mass of the alkali-free aluminoborosilicate glass, the raw materials of the alkali-free aluminoborosilicate glass composite clarifier include, by mass percentage, 0.8% to 5.5% of halogen alkaline earth metal salt, 0.13% to 0.4% of lanthanum oxide, 0.01% to 0.22% of tin dioxide and 0.1% to 0.3% of cerium dioxide.

3. The alkali-free aluminoborosilicate glass composite clarifier according to claim 1, characterized in that: Based on the total mass of the alkali-free aluminoborosilicate glass, the raw materials of the alkali-free aluminoborosilicate glass composite clarifier include, by mass percentage, 1.8% to 5.5% of halogen alkaline earth metal salts, 0.13% to 0.18% of lanthanum oxide, 0.17% to 0.22% of tin dioxide and 0.1% to 0.3% of cerium dioxide.

4. The alkali-free aluminoborosilicate glass composite clarifier according to claim 1, 2 or 3, characterized in that: The alkaline earth metal halide salt is one or more of sodium chloride, strontium chloride and calcium chloride.

5. The alkali-free aluminoborosilicate glass composite clarifier according to claim 4, characterized in that: The alkaline earth metal halide salt comprises sodium chloride, strontium chloride and calcium chloride, and the mass ratio of the sodium chloride, strontium chloride and calcium chloride is (0.15-2.2): (0.15-3.4): (0.1-1.6).

6. The alkali-free aluminoborosilicate glass composite clarifier according to claim 1, 2 or 3, characterized in that: The particle size of the alkaline earth metal halogenide salt is less than 400 μm, the particle size of the lanthanum oxide is less than 12 μm, the particle size of the tin dioxide is less than 90 μm, and the particle size of the cerium dioxide is less than 10 μm.

7. The alkali-free aluminoborosilicate glass composite clarifier according to claim 1, 2 or 3, characterized in that: The particle size of the alkaline earth metal halide is 45 to 350 μm, the particle size of the lanthanum oxide is 1 to 10 μm, the particle size of the tin dioxide is 20 to 85 μm, and the particle size of the cerium dioxide is 3 to 8 μm.

8. A clarification method for alkali-free aluminoborosilicate glass composite clarifier, characterized in that: The method comprises the following steps: mixing, melting, clarifying, molding and annealing the raw materials of the alkali-free aluminoborosilicate glass composite clarifier according to any one of claims 1 to 7 with glass raw materials in sequence to obtain the alkali-free aluminoborosilicate glass; wherein, based on the total mass of the alkali-free aluminoborosilicate glass, the glass raw materials, in terms of mass percentage, include: SiO2 55% to 70%, Al2O3 15% to 18%, B2O3 1% to 8%, MgO 2% to 4%, CaO 3% to 5%, SrO 1% to 4% and BaO 3% to 8%; the mass of the alkali-free aluminoborosilicate glass composite clarifier is 0.5% to 6% of the total mass of the alkali-free aluminoborosilicate glass.

9. The clarification method of the alkali-free aluminoborosilicate glass composite clarifier according to claim 8, characterized in that: The mass of the alkali-free aluminoborosilicate glass composite clarifier is 1.4% to 6% of the total mass of the alkali-free aluminoborosilicate glass.

10. The clarification method of the alkali-free aluminoborosilicate glass composite clarifier according to claim 8, characterized in that: The melting temperature is 1300-1680° C. and the melting time is 2-12 hours.

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