Preparation method of advanced screen display ZnO-Al2O3-SiO2-based glass substrate

Abstract

The invention discloses a preparation method of an advanced screen display ZnO-Al2O3-SiO2-based glass substrate, and belongs to the technical field of novel preparation processes of screen display glass materials. According to the technical scheme, the method is characterized in that ZnSiO3 and Al2 (SiO3) 3 are selected as glass melting raw materials, one or more of calcium borate or barium borate is selected as a cosolvent, the raw materials can be completely melted and reacted at 1260 DEG C, and the temperature of the raw materials is far lower than that of conventional oxide preparation; the clarifying agent is selected from one or more of cerium dioxide, barium sulfate, calcium sulfate or zirconium oxide, and the auxiliary materials not only serve as the clarifying agent, but also play a role of a nucleating agent in the glass crystallization process, so that sufficient use and compatible chemical effects of additives are formed, and excessive introduction of impurities is avoided. The clear glass clarification time and temperature treatment process are beneficial to regulation and control of crystallization degree and hardness, and the stability of the substrate in the process of preparing the TFT-LCD on the substrate glass in the later period is guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of a new preparation process of screen display glass materials, and particularly relates to a preparation method of high-generation screen display ZnO-Al2O3-SiO2-based glass substrates. BACKGROUND

[0002] Liquid crystal panels need to use two pieces of glass substrates, which are respectively used as color filter bottom plates and bottom glass substrates, so that the glass substrate is a basic component of the liquid crystal panel and a core basic material of the flat panel display. In the panel display industry, the size of the glass substrate is generally used to represent the "generation", and generally, the 8.5-generation and above large-size glass substrates are called high-generation glass substrates. The high-generation glass substrates have the characteristics of large size and can manufacture 55-inch and above panels. Under the trend of large screen of electronic products, the high-generation glass substrate becomes the development direction of the industry, and the quality and performance of the high-generation glass substrate directly affect the display effect and service life of the liquid crystal display panel. At present, the highest generation reaches 10.5 generation / 11 generation, which is produced by three major production enterprises, namely, Corning in the United States, Asahi in Japan and Nippon Electric Glass in Japan. The 8.5-generation glass substrate independently produced by China is jointly researched and developed by the China Building Material Glass New Material Research Institute and Zhejiang University, and successfully put into operation in the Kaisheng Technology Group Bengbu Zhongguang Optoelectronics Technology Co., Ltd. in 2019, so that China becomes the third country in the world to independently produce high-generation TFT-LCD glass substrates.

[0003] The high-generation substrate glass used at the present stage belongs to alkali-free aluminoborosilicate glass. The following table shows the chemical composition and physical and chemical properties of several typical commercial ultrathin alkali-free aluminoborosilicate glass substrates of four foreign companies, namely, Corning (the United States), Asahi (Japan), NEG (Japan) and AvanStrate (Sino-US joint venture).

[0004]

[0005] Several necessary conditions that the glass whisker as high generation glass substrate should meet: 1) avoiding alkali metal oxide, when preparing screen display material (such as transparent conductive film, insulating film, metal film, semiconductor film, etc.) on the surface of the bottom substrate glass, the processing temperature is in the region of 500-600℃, if there is alkali metal oxide (such as Li2O, Na2O, K2O, etc.) in the glass component, the alkali metal ion is easy to diffuse from the substrate glass into the deposited material under heat, causing the liquid crystal and thin film transistor in the semiconductor layer to be "poisoned", thereby reducing the thin film characteristics and shortening the service life of the display; 2) suitable thermal expansion coefficient, the thermal expansion coefficient of the substrate glass not only needs to match the thin film semiconductor material, but also often needs to match other thin films (such as conductive, corrosion-resistant, etc.) on the semiconductor surface, otherwise it is easy to cause thin film damage leading to display device defects. The thermal expansion coefficient of the substrate glass is preferably 30x10 -7 / ℃-35x10 -7 / ℃; 3) high thermal stability, in the TFT-LCD manufacturing process, the substrate glass needs to withstand repeated heat treatment, and the heating temperature is as high as 625℃, the substrate glass not only needs to maintain good rigidity, but also needs to maintain the stability of the glass structure during cooling; 4) chemical corrosion resistance, during the preparation of TFT-LCD on the substrate glass, it needs to be cleaned and etched by various strong acid and strong base chemical solutions, and even needs to use buffered hydrofluoric acid solution, therefore the substrate glass must have good chemical corrosion resistance; 5) light weight and high strength, under the premise of the development requirement of large-size screen, the substrate glass also needs to develop correspondingly in large size and thin type, in order to reduce the weight of the entire display, in addition to reducing the thickness of the glass substrate, the density of the glass also needs to be reduced; 6) few defects on the surface and inside, the substrate glass needs to have good surface and internal quality, the film thickness of the thin film element on the substrate glass is several tens to several hundred nanometers, and the electrode and line width of the element is generally in micrometer level. If the defects (scratches, scratches, surface concave-convex, dust, etc.) on the surface of the substrate glass are greater than 25μm, it will cause circuit disconnection, poor adhesion of the thin film and other defects. If the roughness of the glass surface reaches 1μm, it will cause the picture to be not smooth, and the small bubbles, stripes and other defects in the substrate glass will cause errors in the display, affecting the display image quality. These hard conditions are mainly determined by the chemical composition of the prepared substrate glass, and secondly by the substrate preparation process. SUMMARY

[0006] The technical problem solved by the present application is to provide a preparation method of high generation screen display ZnO-Al2O3-SiO2-based glass substrate suitable for float glass process and beneficial to crystallization degree and hardness control.

[0007] To solve the above technical problems, the following technical solutions are adopted: the glass melting raw material is ZnSiO3 and Al2(SiO3)3, wherein the raw material ZnSiO3 is obtained by self-preparation, and the chemical reaction equation is: Zn+H2SiO3→ZnSiO3+H2O; the fluxing agent is one or more of calcium borate or barium borate; the raw material can be completely melted at 1260°C, which is much lower than the temperature for preparation by using oxides in the conventional way; the fining agent is one or more of cerium dioxide, barium sulfate, calcium sulfate or zirconium oxide; these auxiliary materials not only act as fining agents, but also act as crystal nucleus agents in the glass crystallization process, and the glass will be entirely crystallized. The ZnO-Al2O3-SiO2 base glass substrate for developing the substrate has different crystal types due to different compositions or heat treatment systems. Below 850°C, the glass is crystallized into zincite (ZnO·Al2O3·8SiO2); at 950-1000°C, the glass is crystallized into zinc spinel (ZnO·Al2O3) and willemite (2ZnO·SiO2). The glass crystallization has a dual effect, which can improve the strength of the glass but reduce the visible light transmittance.

[0008] The application discloses a preparation method of a high-generation screen display ZnO-Al2O3-SiO2 base glass substrate. ZnSiO3 powder and Al2(SiO3)3 powder are used as glass melting raw materials, and the raw materials are melted at 1250-1350°C under the joint action of a fluxing agent, a fining agent and a crystal nucleus agent, and then are subjected to acid washing, raw material melting and annealing treatment to finally obtain the high-generation screen display ZnO-Al2O3-SiO2 base glass substrate. The fluxing agent is one or more of calcium borate or barium borate, and the fining agent and the crystal nucleus agent are simultaneously one or more of cerium dioxide, barium sulfate, calcium sulfate or zirconium oxide.

[0009] Further, the specific preparation process of the ZnSiO3 powder is as follows: equal-molar Zn powder and H2SiO3 are taken and mixed, the solid phases of the Zn powder and the H2SiO3 are reacted at 160-170°C, and after sufficient stirring and reaction, the product is taken out and subjected to ball milling and crushing to obtain the ZnSiO3 powder.

[0010] Further, the molar ratio of the ZnSiO3 powder to the Al2(SiO3)3 powder is 1:1, the addition amount of the fluxing agent is 0.5%-3% of the total weight of the glass raw material, and the addition amount of the fining agent is 0.3%-5% of the total weight of the glass raw material.

[0011] Further, the fluxing agent is preferably barium borate, the addition amount of the barium borate is 2% of the total weight of the glass raw material, the fining agent is preferably a combination of cerium dioxide and barium sulfate, the addition amount of the cerium dioxide is 0.5% of the total weight of the glass raw material, and the addition amount of the barium sulfate is 0.5% of the total weight of the glass raw material.

[0012] Further, the specific process of the melting reaction is as follows: the ZnSiO3 powder and the Al2(SiO3)3 powder are weighed and added with a fluxing agent and a fining agent for grinding and mixing, and then are loaded into a high-temperature furnace for sintering, and the temperature control settings in the sintering stage are as follows:

[0013] Preheating stage: heating to 400℃ at a heating rate of 10℃ / min, and keeping for 20min, for promoting the full reaction of the first-step material and removing the residual moisture in the raw material;

[0014] Activation stage: heating to 900℃ at a heating rate of 10℃ / min, and keeping for 10min, for ensuring the uniformity of the temperature inside and outside the raw material powder and the full energy of the ions;

[0015] Sintering stage: heating to 1300℃ at a heating rate of 10℃ / min, and keeping for 20min, for making the reaction full and uniform;

[0016] Annealing stage: cooling to room temperature with the furnace;

[0017] The obtained glass is called "one-step glass body", and the product is crushed and ball milled to obtain a glass powder.

[0018] Further, the specific process of the acid washing is as follows: the glass powder is subjected to acid washing for removing the impurities such as Na, Fe, Mg and other metal oxide impurities in the raw material, the combined acid solution used in the acid washing process is composed of a 40wt% hydrofluoric acid solution and a 98wt% concentrated sulfuric acid solution at a volume ratio of 1:0.05, the acid washing temperature is 35℃±2℃, the acid washing time is 1-2min, and after the acid washing, the glass is rinsed with high-purity water for acid removal until the rinsing liquid is neutral.

[0019] Further, the specific process of the raw material melting and annealing is as follows: the glass powder after the acid washing is dried at 80-100℃, and then is loaded into a glass melting furnace for sample melting, and the temperature control settings in the melting stage are as follows:

[0020] Temperature rising stage: heating to 900℃ at a heating rate of 10℃ / min, and keeping for 10min; and then heating to 1400℃ at a heating rate of 10℃ / min, and keeping for 20min; the molten body is transferred to a tungsten tank with a tin lining for simulating the float forming;

[0021] Cooling stage: The glass melt in the tungsten bath is cooled to 1300℃ at a cooling rate of 5℃ / min and held for 10min to fully remove air bubbles in the melt. Then the glass melt is removed from the melting furnace along with the tungsten bath. Simulating the float forming annealing process, the glass melt moves from the high temperature zone at the front of the tin bath to the low temperature zone at the tail of the tin bath along the transverse temperature gradient formed in the tin bath. The temperature at the tail of the tin bath is maintained at 400℃. The glass melt is air-cooled to room temperature under flowing nitrogen conditions along with the tungsten bath. Then the tin is removed to obtain the high-generation display ZnO-Al2O3-SiO2 based glass substrate.

[0022] The present invention has the following advantages and beneficial effects:

[0023] 1) The ZnO-Al2O3-SiO2 substrate glass composition developed in this invention is different from the B2O3-Al2O3-SiO2 system of the substrate composition of the four major international companies in this industry; the glass composition formula is also different from the conventional ZnO-Al2O3-SiO2 microcrystalline glass. The raw materials selected are ZnSiO3 and Al2(SiO3)3, which can melt and react at a lower temperature. The selected clarifying agent also acts as a nucleating agent in the crystallization stage, forming a chemical effect that fully utilizes and is compatible with the additives, without introducing too much impurity.

[0024] 2) The ZnO-Al2O3-SiO2 substrate glass developed in this invention is suitable for float glass manufacturing process. The clear glass clarification time and temperature treatment process are conducive to the control of crystallinity and hardness, ensuring the stability of the substrate in the subsequent fabrication of TFT-LCD on the substrate glass. Attached Figure Description

[0025] Figure 1 Optical photographs of the samples prepared in this embodiment of the invention.

[0026] Figure 2 A flowchart illustrating the sample preparation process in this embodiment of the invention.

[0027] Figure 3 XRD pattern of the sample in this embodiment of the invention. Detailed Implementation

[0028] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.

[0029] Example

[0030] The specific preparation steps for ZnO-Al2O3-SiO2-based glass substrates are as follows:

[0031] (1) Preparation of ZnSiO3 powder

[0032] Equal molar amounts of Zn powder and H2SiO3 were taken and mixed evenly. The solid phases of Zn powder and H2SiO3 were reacted in an oil bath at a temperature of 160-170℃. After thorough stirring and natural cooling after the reaction was completed, the product was taken out and ball-milled to obtain ZnSiO3 powder.

[0033] (2) Raw material melting

[0034] Weigh out equimolar amounts of ZnSiO3 powder and Al2(SiO3)3 powder. Use barium borate as the flux, adding it at 2% of the total weight of the glass raw material. Use a combination of cerium dioxide and barium sulfate as the clarifying agent, adding cerium dioxide at 0.5% of the total weight of the glass raw material and barium sulfate at 0.5% of the total weight of the raw material. Grind and mix the powders, then place them in a high-temperature furnace for firing. The temperature control settings during the firing stage are as follows:

[0035] Preheating stage: Heat to 400℃ at a heating rate of 10℃ / min and hold for 20min to promote the full reaction of the materials in the first step and remove residual moisture from the raw materials;

[0036] Activation stage: Heat to 900℃ at a heating rate of 10℃ / min and hold for 10min to ensure uniform temperature inside and outside the raw material powder and that each ion obtains sufficient energy;

[0037] Sintering stage: Heat to 1300℃ at a heating rate of 10℃ / min and hold for 20min to ensure a thorough and uniform reaction;

[0038] Annealing stage: Cool to room temperature in the furnace;

[0039] The resulting glass is called "one-step glass". The product is crushed and ball-milled to obtain glass powder.

[0040] (3) Pickling

[0041] The glass powder prepared by crushing and ball milling was acid-washed to remove impurities such as metal oxides like Na, Fe, and Mg from the raw materials. The acid washing process used a combined acid solution consisting of a 40wt% hydrofluoric acid solution and a 98wt% concentrated sulfuric acid solution at a volume ratio of 1:0.05. The acid washing temperature was 35℃±2℃, and the acid washing time was 1-2 minutes. After acid washing, the glass was rinsed with high-purity water for deacidification treatment until the pH of the rinsing solution was neutral.

[0042] (4) Sample melting and annealing

[0043] The acid-washed glass powder material was first dried at 90°C, and then placed in a glass melting furnace for sample melting. The temperature control settings during the melting stage were as follows:

[0044] Heating stage: Heat to 900℃ at a heating rate of 10℃ / min and hold for 10min; then heat to 1400℃ at a heating rate of 10℃ / min and hold for 20min; transfer the melt to a tungsten bath, with the bottom of the tungsten bath lined with metallic tin (simulating float forming);

[0045] Cooling stage: The molten glass in the tungsten bath is cooled to 1300℃ at a rate of 5℃ / min and held for 10min to fully remove air bubbles from the melt. Then, the molten glass is removed from the melting furnace along with the tungsten bath, simulating the float forming annealing process (the molten glass moves from the high-temperature zone at the front of the tin bath along the transverse temperature gradient formed in the tin bath to the low-temperature zone at the tail of the tin bath, with the temperature at the tail of the tin bath maintained at 400℃). The molten glass is then air-cooled to room temperature under flowing nitrogen conditions, and then tin is removed to obtain the sample ZnO-Al2O3-SiO2-based glass substrate.

[0046] Test the prepared glass samples, Figure 1 This is an optical photograph of the sample; its thickness is 2.665 mm and its density is 2.43 g / cm³. 3 The thermal conductivity is 1.52 W / (m·K), the flexural strength measured using IOT-300 is 210 MPa, the visible light transmittance is 81%, the glass refractive index difference is 0.23%, and the coefficient of thermal expansion is 36.4 × 10⁻⁶. -7 / K; Corrosion resistance test: in 10wt% HF solution at 20℃ for 20 min and in 5wt% NaOH solution at 95℃ for 6 h, the weight loss per unit surface area was 6.2 mg / cm². 2 and 2.1 mg / cm 2 DSC analysis of the glass revealed small endothermic and exothermic peaks at 890℃ and 959℃, respectively, indicating weak crystallization ability. Crystallization can be well controlled through heat treatment, with a Tg of 995℃. In the examples, the samples were prepared by rapid cooling, so the XRD patterns of the samples, as shown... Figure 3 The material shown exhibits only weak crystallization. To improve the material's strength, it is possible to control... Figure 2 The crystallization time or a two-step heat treatment method can be used to prepare it.

[0047] Compared to the necessary conditions for the substrate, which are determined by its composition, the sample obtained by this method meets the requirements of being free of alkali metals, having high thermal stability, being lightweight and having high strength, but its coefficient of thermal expansion is slightly higher than the ideal conditions.

[0048] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-generation display ZnO-Al2O3-SiO2-based glass substrate, characterized in that: Using ZnSiO3 powder and Al2(SiO3)3 powder as glass melting raw materials, a melting reaction is carried out at 1250-1350℃ under the combined action of flux, clarifying agent and nucleating agent. Then, after acid washing, raw material melting and annealing treatment, a high-generation display ZnO-Al2O3-SiO2 based glass substrate is finally obtained. The flux is one or more of calcium borate or barium borate, and the clarifying agent and nucleating agent are one or more of cerium dioxide, barium sulfate, calcium sulfate or zirconium oxide.

2. The method for preparing a high-generation display ZnO-Al2O3-SiO2-based glass substrate according to claim 1, characterized in that... The specific preparation process of the ZnSiO3 powder is as follows: Equal molar amounts of Zn powder and H2SiO3 are mixed. The solid phases of Zn powder and H2SiO3 are reacted at 160-170℃. After thorough stirring and natural cooling after the reaction is completed, the product is taken out and ball-milled to obtain ZnSiO3 powder.

3. The method for preparing a high-generation display ZnO-Al2O3-SiO2-based glass substrate according to claim 1, characterized in that: The molar ratio of ZnSiO3 powder to Al2(SiO3)3 powder is 1:1, the amount of flux added is 0.5% to 3% of the total weight of glass raw materials, and the amount of clarifying agent added is 0.3% to 5% of the total weight of glass raw materials.

4. The method for preparing a high-generation display ZnO-Al2O3-SiO2-based glass substrate according to claim 3, characterized in that: The co-solvent is preferably barium borate, and the amount of barium borate added is 2% of the total weight of the glass raw material. The clarifying agent is preferably a combination of cerium dioxide and barium sulfate, wherein the amount of cerium dioxide added is 0.5% of the total weight of the glass raw material, and the amount of barium sulfate added is 0.5% of the total weight of the glass raw material.

5. The method for preparing a high-generation display ZnO-Al2O3-SiO2-based glass substrate according to claim 1, characterized in that: The specific process of the melting reaction is as follows: ZnSiO3 powder and Al2(SiO3)3 powder are weighed, and a flux and clarifying agent are added for grinding and mixing. Then, the powder is placed in a high-temperature furnace for firing. The temperature control settings during the firing stage are as follows: Preheating stage: Heat to 400℃ at a heating rate of 10℃ / min and hold for 20min to promote the full reaction of the materials in the first step and remove residual moisture from the raw materials; Activation stage: Heat to 900℃ at a heating rate of 10℃ / min and hold for 10min to ensure uniform temperature inside and outside the raw material powder and that each ion obtains sufficient energy; Sintering stage: Heat to 1300℃ at a heating rate of 10℃ / min and hold for 20min to ensure a thorough and uniform reaction; Annealing stage: Cool to room temperature in the furnace; The resulting glass is called "one-step glass". The product is crushed and ball-milled to obtain glass powder.

6. The method for preparing a high-generation display ZnO-Al2O3-SiO2-based glass substrate according to claim 1, characterized in that: The specific pickling process is as follows: the glass powder is pickled to remove impurities from the raw material. The combined acid solution used in the pickling process consists of a 40wt% hydrofluoric acid solution and a 98wt% concentrated sulfuric acid solution with a volume ratio of 1:0.

05. The pickling temperature is 35℃±2℃ and the pickling time is 1-2 minutes. After pickling, the glass is rinsed with high-purity water for deacidification treatment until the pH value of the rinsing solution is neutral.

7. The method for preparing a high-generation display ZnO-Al2O3-SiO2-based glass substrate according to claim 1, characterized in that: The specific process of raw material melting and annealing is as follows: the acid-washed glass powder is first dried at 80-100℃, and then placed in a glass melting furnace for sample melting. The temperature control settings during the melting stage are as follows: Heating stage: Heat to 900℃ at a heating rate of 10℃ / min and hold for 10min; then heat to 1400℃ at a heating rate of 10℃ / min and hold for 20min; transfer the melt to a tungsten bath, with the bottom of the tungsten bath lined with metallic tin, to simulate float forming; Cooling stage: The glass melt in the tungsten bath is cooled to 1300℃ at a cooling rate of 5℃ / min and held for 10min to fully remove air bubbles in the melt. Then the glass melt is removed from the melting furnace along with the tungsten bath. Simulating the float forming annealing process, the glass melt moves from the high temperature zone at the front of the tin bath to the low temperature zone at the tail of the tin bath along the transverse temperature gradient formed in the tin bath. The temperature at the tail of the tin bath is maintained at 400℃. The glass melt is air-cooled to room temperature under flowing nitrogen conditions along with the tungsten bath. Then the tin is removed to obtain the high-generation display ZnO-Al2O3-SiO2 based glass substrate.

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