Manufacturing process for high-generation TFT-LCD glass substrates

Abstract

This float process for high-generation TFT-LCD glass substrates involves the following steps: in the compounding step, blowing and vibration methods are used to assist in the addition of raw materials based on an optimized raw material formulation to improve the uniformity and stability of the composition; in the melting step, three-dimensional electric gas combined heating is employed to achieve sufficient melting; in the clarification step, platinum channel clarification and forced turbulence homogenization are used to complete efficient clarification and homogenization; in the molding step, thinning quality is improved through precise control of the heating unit and micro-edge drawing machine; in the annealing step, fine annealing is achieved through precise annealing control of independent areas; and in the grinding step, grinding is performed using specially designed chamfered grinding discs and grinding pads, and grinding pads of specific hardness to achieve excellent processing effects.

Description

Technical Field

[0001] This application relates to the field of manufacturing glass substrates, and particularly to the float manufacturing process of high-generation TFT-LCD glass substrates.

Background Art

[0002] The electronic information display industry is an important backbone industry of China's national economy. China is the world's largest producer of liquid crystal panels, accounting for 70% of the world's total production capacity. High-generation TFT-LCD glass substrates are the core materials and major strategic materials of the electronic information display industry and the general semiconductor industry. The annual demand for high-generation TFT-LCD glass substrates in China exceeds 300 million square meters.

[0003] The quality and performance of high-generation TFT-LCD glass substrates have a significant impact on the quality of display panels such as resolution, transmittance, refresh rate, and viewing angle. Therefore, very high requirements are placed on the quality of the interior and surface of the substrates. Bubbles, stones, tin adhesion, dripping, and scratches are indicators that are strictly controlled in the manufacturing process of glass substrates. Therefore, high-generation TFT-LCD glass substrates have complex production technologies, production management accuracies comparable to those of the semiconductor industry, and boast the highest level in the world's modern large-scale glass manufacturing field.

[0004] There are two main molding processes for high-generation TFT-LCD glass substrates: float and overflow. The float molding process has advantages such as a wide molding plate and low production costs, but it also has problems such as significant inter-process influence, a large number of control parameters, high difficulty in adjustment and control, and difficulty in maintaining stable production conditions. In addition, in the float molding process, the glass liquid is thinned and molded onto the surface of the metal tin liquid, and the contact surface where the glass liquid and the tin liquid surface come into contact has minute defects such as small solder spots and scratches, and this contact surface is also the processing surface for downstream LCD panel manufacturers. The problem of how to manufacture high-quality, high-generation TFT-LCD glass substrates with excellent mechanical strength, thermal stability, and thermal shrinkage properties, and with few surface and internal defects using the float process, is a critical technological challenge that needs to be solved urgently today. [Overview of the project] [Problems that the invention aims to solve]

[0005] To solve the technical challenges present in the prior art, the applicant's scientists, through long-term collaboration and tireless efforts by a large team, have made technological innovations in multiple processes of the display glass substrate manufacturing process, exploring and utilizing the advantages of each process, conducting combined innovation research between processes, and ultimately achieving a breakthrough in the float process for high-generation TFT-LCD glass substrates. This process fully utilizes resources, has synergistic and complementary advantages, and forms a display glass substrate production process with an organically integrated production line. This process enables the production of high-generation TFT-LCD glass substrates with relatively superior control and performance indicators such as bubbles, stone, tin adhesion, drips, and scratches. It effectively reduces or eliminates defects in the glass substrate, significantly improving the quality of the glass substrate and providing a solution for the production of micro-defect-free, high-quality, high-generation display glass substrates.

[0006] The present invention provides a glass substrate manufacturing process that includes steps such as compounding, melting, clarifying and homogenizing, molding, annealing, grinding, cleaning, and packaging. [Means for solving the problem]

[0007] In the compounding process, the raw material composition is preferably selected to consist of SiO2, Al2O3, B2O3, MgO, CaO, SrO, ZrO2, and P2O5 in a specific ratio relationship. This effectively reduces the boron volatilization rate during glass molding and eliminates problems such as non-uniformity of components due to boron volatilization. The aluminosilicate glass substrate produced using this substrate has properties such as a high strain point, high Young's modulus, high hardness, appropriate coefficient of thermal expansion, low thermal contraction, and low defects, meeting the special requirements of high-generation TFT-LCD glass substrates.

[0008] Preferably, an electronic scale feeding system is used, which combines nozzle spraying and air hammer vibration. After each raw material is weighed in the electronic weighing bucket and then added, the air pressure supply valve opens, and at the same time, the nozzle sprays onto the inner wall of the electronic weighing bucket, and the air hammer knocks and vibrates the electronic weighing bucket, thereby synchronously discharging the raw materials that have accumulated on the inner wall of the electronic weighing bucket. This ensures that the composition of each compound is constant during the mixing process and ensures the quality stability of the glass substrate.

[0009] In the melting process, a heating method combining electric melting assistance and total oxygen combustion is preferably used. For electric heating, a molybdenum electrode or a tin oxide electrode can be used and may be installed on the melting furnace pool wall and / or pool bottom. The combustor may be installed on the melting furnace roof and / or breast wall. Preferably, the melting furnace is provided with a foaming device and a furnace depression to perform primary degassing and clarification of the molten glass liquid and to remove bubbles with a diameter of 0.2 mm or more from the molten glass liquid. With the above setup, synchronous heating of the raw materials in the melting furnace is promoted, the glass liquid is dissolved sufficiently and efficiently, and primary degassing and clarification of the melting furnace removes bubbles with a diameter of 0.2 mm or more in the melting furnace section, and after degassing, the number of bubbles with a diameter of 0.2 mm or more in the molten glass liquid becomes ≤0.1 bubbles / kg. Subsequently, bubbles with a diameter of 0.2 mm or less are removed by precision clarification of the platinum channel, and finally the glass substrate is sufficiently degassed and clarified, enabling the acquisition of high-quality glass liquid.

[0010] In the clarification and homogenization process, clarification is preferably performed using a platinum channel that combines two or more high-temperature platinum channels and one low-temperature platinum channel, and homogenization is forced using an optimized stirring and turbulence method. For a single platinum channel, the reduced diameter of the platinum channel reduces the temperature difference of the glass liquid on the same cross-section of the passage, the improved turbulence process enhances the efficiency of homogenization, promotes sufficient uniformity of the temperature and components of the glass liquid flow, and the lowering of the glass liquid level shortens the floating distance of bubbles, working together in accordance with the optimized raw material formulation to improve the degassing efficiency of small bubbles. Due to the special design of the above clarification and homogenization process, defects such as bubbles and streaks are avoided in the glass plate, bubbles in the glass liquid are efficiently removed, and the number of bubbles with a diameter of ≥0.05 mm in the molten glass liquid does not exceed 0.15 bubbles / kg.

[0011] In the molding process, preferably, a grid-shaped heating unit is provided at the top of the solder groove, and multiple micro-edge drawing machines are provided in the molding thinning region. The heating unit is controlled in cooperation with the edge drawing machines, and by adjusting the output power of each lateral heating unit, the lateral temperature difference of the solder groove is adjusted, thereby achieving different viscosities at each part of the glass ribbon laterally. Multiple micro-edge drawing machines optimize and combine the thinning force to adjust the precision, thereby jointly realizing precise thinning of the high-generation liquid crystal glass plate with multi-force action in accordance with the appropriate main drive traction force. The overall thickness difference of the manufactured high-generation TFT-LCD glass substrate is less than 0.015 mm.

[0012] In the annealing process, preferably, an annealing kiln structure precisely controlled by a three-dimensional grid temperature is used. By employing methods such as cooling with turbulence-free cooling ducts, conveying with low-thermal-conductivity ceramic rollers, curtain partition isolation, and differentiated design for annealing kiln heat retention, airflow disorder is avoided, temperature field fluctuations are reduced, lateral temperature differences of the glass substrate are decreased, the lateral temperature of large ultrathin glass substrates is kept constant, and requirements such as precise matching of the temperature in each area of ​​the annealing kiln with the substrate annealing curve are met, achieving a perfect match between the temperature field and the annealing curve, and sufficiently removing stress from the glass substrate.

[0013] In the grinding process, three grinding pads—coarse grinding, fine grinding, and grinding—with hardness ratios of 90HD~100HD:60HD~70HD:35HD~40HD are used to sequentially grind and polish the glass substrate. By optimizing the width ratio between the grinding surface and grinding groove at the non-edge, and by providing chamfers at the periphery of the grinding disc and at the position of the grinding pad furthest from the grinding disc, and by making the chamfer angle on the grinding disc greater than or equal to the chamfer angle on the grinding pad, grinding quality is improved, grinding scratches are reduced, and the grinding effect is enhanced.

[0014] The float production process for the above-mentioned high-generation TFT-LCD glass substrates precisely controls the manufacturing process and achieves an organic synergistic effect in the linkage of each production process. This process enables the leading industrial stable mass production of high-quality, high-generation float electronic glass substrates with minimal defects. [Effects of the Invention]

[0015] Beneficial effects of the present invention: The present invention explores and utilizes the advantages of multiple processes in the high-generation TFT-LCD glass substrate float production process, conducts combined innovation research between processes, and organically integrates the production line to form a display glass substrate production process with outstanding advantages, synergies, and complementarity. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram of the overall flow of the glass substrate manufacturing process. [Figure 2] It is a schematic diagram of a cooperation engineering feeding system. [Figure 3] It is a schematic diagram of the front cross-section of the melting furnace in the glass raw material melting process. [Figure 4] It is a schematic plan view of the clarification and homogenization process system in the clarification and homogenization process. [Figure 5] It is a schematic diagram of the cross-section of the solder groove in the forming process. [Figure 6] It is a schematic plan view of the forming thin-wall region of the solder groove in the forming process. [Figure 7] It is a schematic plan view of the annealing kiln in the annealing process. [Figure 8] It is a schematic diagram of the front cross-section of the annealing kiln in the annealing process. [Figure 9] It is a schematic diagram of the grinding process. [Figure 10] It is a schematic diagram of the surface of the glass substrate before and after grinding in the grinding process. [Figure 11] It is a schematic diagram of the general structure of the grinding pad in the grinding process. [Figure 12] It is a schematic diagram of the grinding surface in the grinding process. [Figure 13] It is a schematic diagram of the general structure of the grinding device in the grinding process. [Figure 14] It is an enlarged view of part A in FIG. 11. [Figure 15] It is a schematic diagram of the chamfering of the grinding disk in the grinding process. [Figure 16] It is a schematic diagram of the chamfering of the grinding pad in the grinding process.

Embodiments for Carrying out the Invention

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all of them. Based on the embodiments of the present application, all other embodiments obtained on the premise that those skilled in the art do not perform creative work all belong to the protection scope of the present application. It is understood that the drawings are only provided for reference and explanation, and are not intended to limit the present application.

[0018] Specifically, the embodiments of this application provide a float manufacturing process for high-generation TFT-LCD glass substrates, and as shown in Figure 1, the glass substrate manufacturing process mainly comprises: A compounding process involves selecting appropriate raw material components, weighing and mixing each component to form a glass compound, A melting step involves heating and melting a uniformly mixed glass compound to form a molten glass liquid, The molten glass liquid is passed through a clarification passage to remove air bubbles and homogenize it in a clarification and homogenization process, The molding process involves spreading and thinning molten glass onto the surface of a tin liquid to form a glass substrate, An annealing process to anneal the glass substrate and remove internal stress in the glass substrate, The process involves cutting the glass substrate to the required size and then performing a grinding process, A cleaning process that performs cleaning on a glass substrate, This includes a packaging step of packaging the qualified glass substrate after cleaning.

[0019] The following explains the technology involved in each process one by one.

[0020] Compounding process: High-generation TFT-LCD glass substrates are required to possess characteristics such as low density, high strain point, appropriate coefficient of thermal expansion, high Young's modulus, resistance to chemical attack, low thermal shrinkage, and minimal defects. Therefore, careful design of the raw material composition is necessary.

[0021] Preferably, materials with the following weight fractions are used: 60-72% SiO2, 13-18% Al2O3, 8.5-10% B2O3, 1-4.5% MgO, 3-8% CaO, 1-5% SrO, 0.5-2% ZrO2, 1-5% P2O5, and 0.1-0.5% SnO2, where SiO2+Al2O3 is 76-85%, (MgO+CaO+SrO) / Al2O3 is 0.4-0.7%, the total amount of alkaline earth metal oxides is 5-11.5%, B2O3 / (B2O3+ZrO2+P2O5) is 0.6-0.9%, and (ZrO2+P2O5) / (MgO+CaO+SrO) is 0.15-0.8%.

[0022] The above-mentioned glass material reduces the boron volatilization rate during glass molding and can control non-uniformity of the glass liquid components due to boron volatilization during the manufacture of glass substrates. Furthermore, this raw material can also promote degassing and clarification of the glass liquid. The aluminosilicate glass substrate manufactured using this raw material has properties such as a high strain point, high Young's modulus, high hardness, appropriate coefficient of thermal expansion, low thermal contraction, and minor defects. Here, the β-OH value is less than 0.5%, the boron volatilization rate is less than 11%, and the coefficient of thermal expansion in the range of 50 to 350°C is 39.5 × 10⁻⁶. -7 The temperature is less than / ℃, the Young's modulus is greater than 78 GPa, the strain point is greater than 690℃, the melting temperature is less than 1690℃, and the thermal shrinkage is less than 11.5 ppm.

[0023] At the same time, the quality requirements for high-generation TFT-LCD glass substrates are far higher than those for other types of glass. This requires that the component composition of high-generation TFT-LCD glass substrates maintain extremely high uniformity and that no significant differences in composition occur. Therefore, strict requirements are placed on the purity, weighing accuracy, and mixing uniformity of each raw material in the composition.

[0024] Preferably, the following electronic scale weighing system that stably controls the glass compounding composition may be employed.

[0025] As shown in Figure 2, the system includes an electronic weighing bucket 101, the bottom of which is a pneumatic supply valve 102, and an air hammer 103 is provided on the outer wall of the electronic weighing bucket 101. The pneumatic supply valve 102 is controlled to open and close by an open solenoid valve 104 and a closed solenoid valve 105, respectively. The open solenoid valve 104 is connected to the air hammer 103, and the open solenoid valve 104 is connected to the first trachea 106 and the second trachea 107. The first trachea 106 is connected to the pneumatic supply valve 102, the second trachea 107 is connected to the air hammer 103, the closing solenoid valve 105 is provided with a third trachea 108, the third trachea 108 is connected to the pneumatic supply valve 102, a nozzle 109 is provided on the upper part of the inner wall of the electronic weighing bucket 101, the nozzle 109 is connected to a fourth trachea 110 extending from the electronic weighing bucket 101, and the fourth trachea 110 and the first trachea 106 are in communication. The nozzle 109 may also be provided in locations where accumulation is likely to occur according to actual demand, and if there are accumulations in multiple locations, multiple nozzles 109 may be provided accordingly. The above system enables stable blending of each component in the glass raw material formulation. Specifically, after the electronic weighing bucket 101 weighs each glass raw material, when the air pressure supply valve 102 opens, the nozzle 109 blows air onto the inner wall of the electronic weighing bucket 101, and the air hammer 103 knocks the electronic weighing bucket 101, causing the raw material accumulated on the inner wall of the electronic weighing bucket 101 to be discharged synchronously. This ensures a constant composition of each component during the liquid crystal glass formulation process and secures the quality of the glass substrate.

[0026] Using the above compounding process, we improve the quality and performance of the glass substrate from the source, and ensure the accuracy and stability of the compounding.

[0027] Melting process: After completing the above formulation, the glass raw materials are melted in the melting process.

[0028] Preferably, the following melting process may be employed.

[0029] As shown in Figure 3, electrodes 202 are arranged symmetrically or in a staggered pattern on the inner walls and / or bottom of the melting furnace 201, and oxygen burning guns 203 are provided on the roof and / or breast wall of the melting furnace 201. When provided on the roof, the oxygen burning guns are vertically distributed, the flame nozzles are directed vertically downward, and the flames can contact the surface of the glass molten liquid in the melting furnace 201. When provided on the breast wall, the oxygen burning guns are positioned horizontally. Complete melting of the glass raw material is achieved by direct heating of the electrodes and radiant heating of total oxygen combustion. Preferably, the melting furnace is further provided with a foaming device 204 and a furnace recess 205 to perform primary defoaming and clarification of the molten glass molten liquid and to promote the removal of large bubbles in the glass molten liquid. By carefully blending the raw materials, utilizing a three-dimensional, all-around electric-gas-total-oxygen combustion combined heating system, and leveraging the effects of foaming and the furnace depressions, the number of bubbles with a diameter of 0.2 mm or more in the molten glass liquid is significantly reduced, resulting in a number of bubbles with a diameter of 0.2 mm or more of ≤ 0.1 bubbles / kg.

[0030] By employing the above process, the glass raw material is heated at multiple angles from bottom to top, ensuring that the raw material at each position in the melting furnace is heated uniformly and thoroughly. Simultaneously, the special selection of glass raw material facilitates the cooperation of primary clarification and precision clarification in the clarification and homogenization section of the glass liquid melting furnace, improving the degassing efficiency of the production line system and enhancing the quality of the glass substrate.

[0031] Clarification and homogenization process: The molten glass raw material becomes molten glass liquid, which needs to undergo a clarification and homogenization process before molding.

[0032] Preferably, clarification and homogenization may be performed using the following process.

[0033] As shown in Figure 4, the platinum channel comprises multiple high-temperature platinum channels and one low-temperature platinum channel (combination stirring section, second cooling section, and supply section). The system comprises a first high-temperature platinum channel (310) consisting of a first inlet (311), a first clarifying section (312), a first cooling section A (313), and a first stirring section (314) connected in order, and a second high-temperature platinum channel (320) consisting of a second inlet (321), a second clarifying section (322), a first cooling section B (323), and a second stirring section (324) connected in order, wherein the ends of the first inlet (311) and the second inlet (321) are connected to a melting furnace (201), and the ends of the first stirring section (314) and the second stirring section (324) are both connected to a post-merging stirring section (340), and the post-merging stirring section (340) comprises a low-temperature section consisting of a second cooling section (350) and a supply section (360) in order. Platinum channels are connected, the supply section (360) is connected to a solder groove, the first cooling section A (313) and the first cooling section B (323) are for cooling the flowing glass liquid and controlling the cooling rate so that the stirring section reaches the required process temperature, the second cooling section (350) is for cooling the flowing glass liquid and heating the flowing glass liquid when necessary to satisfy the glass molding requirements, and inside the second cooling section (350) grills with different mounting angles are provided in order from right to left, the mounting angles of adjacent grills are different, so that the holes on the grills are offset, ensuring that turbulence is formed after the glass liquid passes through the grills.

[0034] The above multi-platinum channel clarification and homogenization process reduces the heat load of a single platinum channel, avoids the risk of collapse due to prolonged high-temperature operation of large-diameter platinum channels, and, with smaller diameter platinum channels, reduces the temperature difference between the core temperature of the glass liquid and the contact area with the platinum body at the same cross-section of the passage, improving the stirring and grill turbulence process, increasing the efficiency of homogenization, and improving the homogenization of the glass liquid. This homogenization process enables sufficient uniformity of glass liquid temperature and components, improving the quality of the glass substrate. By lowering the liquid level of the glass liquid, the degassing efficiency of small bubbles is increased, so the number of bubbles with a diameter of ≥0.05 mm in the molten glass liquid does not exceed 0.15 bubbles / kg. The coordinated matching of raw material selection, primary clarification of the melting furnace, and precision clarification and homogenization enables the high-quality elimination of bubbles in the glass liquid.

[0035] Molding process: After completing the above clarification and homogenization process, float thinning molding is performed on the glass liquid.

[0036] Preferably, float thinning molding may be performed using the following process.

[0037] As shown in Figures 5 and 6, the molten glass flows into the shaping solder groove. The solder groove is divided from bottom to top into a groove pool 401, a chest wall 402, and a top cover 403, and in the direction of glass flow, the solder groove is divided into a shaping thinning region 404, a shaping cooling region, and a temperature homogenization region.

[0038] With the glass liquid flow direction defined as the longitudinal direction and the direction perpendicular to the glass liquid flow direction as the transverse direction, the top of the solder groove is divided into a grid of multiple heating units 405, and each heating unit can independently control its heating temperature. Each heating unit is equipped with one or more heating elements, and the TFT-LCD glass substrate has the characteristics of having a high molding temperature and a composition that is easily volatile, so preferably the heating element is a high-density three-phase silicon carbon rod.

[0039] Preferably, the density of grid-shaped heating units is increased in the thin-walled molding region, thereby allowing for more precise temperature control in each region and improving the accuracy and flexibility of temperature control.

[0040] Preferably, a precision thinning system is used for joint control in the thinning region of the molding process, in accordance with the heating system for the solder grooves. Because the TFT-LCD glass liquid has a short shelf life and a small molding temperature range, the spacing between edge drawing machines is reduced, the number of edge drawing machines is increased, and the operating area of ​​the thinning system is reduced within the limited temperature range. This allows the glass ribbon thinning force to be finely distributed across each pair of edge drawing machines, thereby achieving ultra-thin precision molding of the glass substrate. A micro-edge drawing machine 406 is used as the precision thinning system. The edge drawing machine body is smaller than 300 mm, preferably 200-250 mm, and the distance between two adjacent edge drawing machines is smaller than 1000 mm, preferably 500-900 mm. A total of 15-25 pairs of edge drawing machines are provided in the thinning region of the molding process, preferably 18-22 pairs.

[0041] Preferably, at least some of the lateral edge heating units 415 are provided in correspondence with the edge drawing machines, and one edge heating unit corresponds to 1 to 4 edge drawing machines, preferably 2 to 3.

[0042] The control system integrally adjusts each heating unit and edge drawing machine. By adjusting the output power of each heating unit in the lateral direction, the lateral temperature difference in the solder groove is adjusted, thereby adjusting the viscosity difference at each point in the lateral direction of the glass ribbon. The thinning force of the edge drawing machine acts on the edge of the glass ribbon and is transmitted to the middle of the glass ribbon. The adjustment of the lateral temperature difference in the solder groove has an effect on the viscosity of the glass liquid, which is coupled with the adjustment of the edge drawing machine's thinning force to improve the lateral thinning effect of the glass ribbon, achieving an overall thickness difference of ≤0.015mm for high-generation TFT-LCD glass substrates.

[0043] Annealing process: After completing the float molding process described above, the molded glass substrate needs to be annealed.

[0044] Preferably, the following glass annealing process may be used.

[0045] As shown in Figures 7 and 8, a grid-like control system is used in the annealing process to divide the annealing zone into multiple areas 501, and each area 501 can be independently temperature-controlled. Each area is equipped with a temperature sensing device 502, a heating device 503, and a cooling device 504. A cooling duct is used as the cooling device, with an air intake on the outside of the kiln and a centrifugal fan 505 at the air outlet. Air flows through the cooling duct, lowering the temperature of the cooling duct, which in turn lowers the temperature of each area. This system avoids air turbulence.

[0046] The applicant's research has shown that one of the reasons for the poor mechanical properties of liquid crystal glass substrates is the presence of large internal stress in the lateral direction of the same glass substrate. This is due to a mismatch in annealing temperatures in the lateral direction, as the temperature of the lateral edge of the glass substrate is lower than the temperature of the center. Therefore, if temperature control is not differentiated, differences in lateral annealing temperatures are likely to occur, leading to the problem of large internal stress. For this reason, preferably, in at least some of the annealing regions, the temperature of area 506 corresponding to the glass edge is higher than the temperature of area 507 corresponding to the center of the glass.

[0047] Preferably, ceramic rollers are used as conveying rollers 508. Ceramic rollers have excellent heat insulation properties, minimizing heat transfer between the glass substrate and the ceramic rollers, thus avoiding unexpected temperature drops in the glass substrate. A curtain 509 is provided in the annealing kiln, which can be raised and lowered under control. Unlike other float glass, ultrathin glass has a high conveying speed in the annealing kiln, and airflow is easily formed during conveying. The use of a curtain avoids airflow, further contributing to the independence of each region and precise temperature control.

[0048] More preferably, the heat retention layer of the annealing kiln is provided with heat retention materials that have different temperatures from inside to outside, with a higher temperature on the inside and a lower temperature on the outside, and different thermal conductivity in the heat transfer direction of the heat retention layer. A heat retention material with lower thermal conductivity is used as the inner high-temperature layer 510 to reduce the overall thermal conductivity. Furthermore, thermal bridge connections are used for thermal bridges such as connecting plates and plug holes between the inner and outer walls of the annealing kiln to further reduce heat conduction, and the temperature difference between the outer wall and the environment is reduced to 2 / 3 or less of the original temperature difference between the outer wall and the environment. By the above means, temperature fluctuations due to frequent temperature adjustments can be avoided and the temperature stability inside the annealing kiln can be improved.

[0049] The temperature detection devices, heating devices, cooling devices, and curtain lifting devices in each area are all connected to a control unit, which enables automatic and intelligent control of each of the above devices.

[0050] The annealing process of the present invention satisfies the requirement for precise matching of the temperature field and annealing curve of high-generation TFT-LCD glass substrates, reduces the lateral temperature difference of the glass substrate, avoids fluctuations and disorder in the temperature field, effectively removes internal stresses from the glass substrate, and enables differentiation, refinement, automation, and intelligent control of annealing.

[0051] Grinding process: After glass annealing, the glass substrate needs to be ground. Grinding involves removing uneven surfaces, tin deposits, scratches, and other minute defects from the glass surface. By adding chemical components such as abrasives and auxiliary agents, the glass surface becomes smooth and flat, thus achieving the grinding effect.

[0052] Polishing is the process of further smoothing the glass surface after the initial grinding, thereby improving its flatness.

[0053] As shown in Figure 9, the grinding process in this embodiment mainly consists of: A process of cleaning and removing dust from a glass substrate. A process in which a coarse grinding pad is used to perform rough grinding on a glass substrate by adjusting it to the grinding fluid. A process in which a fine grinding pad is used to fine grind a glass substrate after rough grinding by adjusting it to the grinding fluid. The process involves applying a grinding pad to a glass substrate after fine grinding to achieve a grinding effect. This is done in the process of cleaning the glass substrate after polishing.

[0054] In the case where the glass is not ground, the glass surface exhibits the shape shown in (1) in Figure 10, and the glass surface exhibits many irregular shapes and structures, which may result in a decrease in the light transmittance of the glass and distortion of the image.

[0055] Before grinding, the glass needs to be cleaned and dust removed.

[0056] During grinding, the coarse grinding pad provided on the grinding part grinds the glass substrate together with the grinding fluid, grinding the glass substrate from the form shown in (1) in Figure 10 to the form shown in (2) in Figure 10, thereby eliminating the uneven areas of the glass substrate.

[0057] After rough grinding is complete, the fine grinding pad provided on the grinding part grinds the glass substrate together with the grinding fluid, removing very small scratches on the glass substrate and grinding the glass substrate from the form shown in (2) in Figure 10 to the form shown in (3) in Figure 10.

[0058] After the fine grinding is completed, the polishing pad provided on the grinding part, together with the grinding fluid, grinds the glass substrate more deeply. After grinding the glass substrate, the polishing pad grinds away any defects on the glass substrate that are not visible to the naked eye, grinding the glass substrate from the form shown in (3) in Figure 10 to the form shown in (4) in Figure 10, thereby meeting the high-quality requirements for TFT-LCD glass substrates.

[0059] The grinding apparatus required for use during grinding is shown in Figures 11 to 14. The grinding apparatus comprises a grinding disc 620 and a grinding pad 610. The grinding pad 610 is assembled onto the grinding disc 620, and one side of the grinding pad 610 that is not attached to the grinding disc 620 grinds glass. Each grinding pad consists of a grinding substrate 614 and a grinding particle layer 613, and the hardness of the grinding particle layer 613 on different grinding pads 610 is different.

[0060] Regarding the hardness range, the coarse grinding pad, fine grinding pad, and polishing grinding pad are preferably controlled as follows: coarse grinding pad: fine grinding pad: polishing grinding pad, preferably 90HD~100HD:60HD~70HD:35HD~40HD, more preferably 90HD~95HD:60HD~70HD:35HD~40HD, and even more preferably 90HD~95HD:65HD~70HD:35HD~40HD. In the above, HD is the Shore hardness index. As shown in Figures 11 and 12, in order to improve the grinding effect, the grinding pad 610 is provided with grinding grooves 611, and the multiple grinding grooves 611 are in communication with each other for the flow of the grinding fluid. Multiple grinding surfaces 612 are formed on the grinding pad 610, preferably, except for the grinding surface at the edge, the other grinding surfaces are square, and the grinding surfaces 612 grind the surface of the glass substrate.

[0061] The ratio of the width of the ground surface to the ground groove at the non-edge portion is preferably 1:1 to 3:1, more preferably 1.7:1 to 2.3:1.

[0062] In the embodiments of this application, the matching relationship between the grinding pad 610 and the grinding disc 620 also affects the grinding effect of the glass substrate, and this effect is mainly due to the fact that the working surface at the edge of the grinding pad 610 and the processed surface of the glass substrate are not perfectly parallel during grinding.

[0063] In conventional technology, the edge of the grinding pad is basically perpendicular to the workpiece surface. With this structure, during grinding, the edge of the grinding pad may rub against the glass substrate to some extent, and this rubbing may cause wear scratches on the glass.

[0064] Through multiple simulations and studies, the applicant found that a specially designed double chamfer coupling can significantly reduce the rate of friction between the grinding pad and the glass substrate during grinding. The specific method is as follows:

[0065] Rounding is performed on the periphery of the grinding disc 620, and in the embodiment of this application, this rounding is called rounding 621. In the method of manufacturing the rounding, as shown in Figure 15, the side height of the grinding disc is H, the bottom surface of the grinding disc extends vertically upward along the side by a distance h to reach point a, the side of the grinding disc is one side, point a is the corner vertex, the rounding corner is the other side, the intersection of the other side and the bottom surface of the grinding disc is point b, points a and b are connected to form an isosceles triangle with this as one side, and the side length of the isosceles triangle is the radius of the rounding R. Here, h / H = 1:2 to 1:6, preferably 1:3 to 1:5, and more preferably 1:3.5 to 1:5.

[0066] Preferably, the edges of the grinding pad are tightly attached to the rounded edges of the grinding disc 620.

[0067] Simultaneously, as shown in Figures 13 and 14, a chamfer is also provided at the outermost edge of the grinding pad, away from the grinding disc 620, i.e., facing the glass substrate. Preferably, this chamfer is a straight chamfer 615. The installation of this straight chamfer 615, based on the rounding 621, further avoids friction with the glass substrate. As shown in Figure 16, the position of the straight chamfer is at position c on the side surface of the grinding pad, where c is the distance from the bottom surface of the grinding pad, and the thickness of the side surface of the grinding pad is H'. H' / H' = 4:5 to 1:2, preferably 4:5 to 3:5. Regarding the relationship between the chamfer angle of the grinding disc and the chamfer angle of the grinding pad, preferably the chamfer angle of the grinding disc is greater than or equal to the chamfer angle of the grinding pad, more preferably the chamfer angle of the grinding disc is greater than or equal to the chamfer angle of the grinding pad and the chamfer angle of the grinding disc is greater than or equal to 50°, even more preferably the chamfer angle of the grinding disc is greater than or equal to the chamfer angle of the grinding pad and the chamfer angle of the grinding disc is greater than or equal to 60°, and even more preferably the chamfer angle of the grinding disc is greater than or equal to the chamfer angle of the grinding pad and the chamfer angle of the grinding disc is greater than or equal to 75° or the chamfer angle of the grinding pad is greater than or equal to 60°.

[0068] Glass grinding fluid is a material that plays an important role in glass manufacturing and processing. Grinding fluid mainly consists of abrasives, solvents, and other additives, which are suspended in the liquid in the form of particles. The main function of glass grinding fluid is to remove impurities from the glass surface with abrasive particles, thereby achieving the goal of making the glass surface smooth. The glass grinding fluid used in the present invention preferably contains cerium oxide, lanthanum oxide, fluoride, praseodymium oxide, silicon oxide, aluminum oxide, calcium oxide, and iron oxide, with a concentration range of 1 to 10%.

[0069] In the embodiments of this application, the grinding pressure, grinding temperature, and grinding rotation speed can be controlled to improve the grinding effect.

[0070] The grinding pressure may be controlled to 0.01 to 0.3 MPa, preferably 0.01 to 0.28 MPa, more preferably 0.1 to 0.25 MPa, even more preferably 0.1 to 0.2 MPa, and most preferably 0.15 to 0.2 MPa.

[0071] The grinding temperature may be controlled within the range of 20 to 60°C, preferably 20 to 50°C, more preferably 30 to 50°C, and even more preferably 30 to 40°C.

[0072] The grinding rotation speed may be controlled to 5000 rpm to 7000 rpm, preferably 5200 rpm to 6500 rpm, more preferably 5500 rpm to 6300 rpm, and even more preferably 5800 rpm to 6000 rpm.

[0073] The grinding time may be controlled to 30 to 300 seconds, preferably 60 to 240 seconds, and more preferably 80 to 150 seconds.

[0074] Cleaning process: After completing the above process, the glass substrate needs to be cleaned. The cleaning process mainly involves removing any remaining grinding fluid and other impurities from the surface of the glass substrate, which then facilitates surface roughness detection using the Surtronic S-100 series surface roughness tester.

[0075] Deep compound cleaning is performed on the glass substrate using disc brushes, roller brushes, ultrasonic waves, two-fluid systems, etc., to achieve the objective of cleaning the glass surface.

[0076] Packaging process: After cleaning and inspection, the approved glass substrates are packaged to prevent the glass from being damaged by impacts, which could create cracks and gaps and affect the sale of the glass in the market.

[0077] Examples: The embodiments of this application will focus on describing the grinding process of the present invention.

[0078] In the example, the grinding fluid consists of grinding powder (58% cerium oxide content) with cerium oxide as the main component and pure water with a 0.2 MΩ impedance, with a concentration range of 4%. In the following grinding steps, grinding is performed based on the components of this glass grinding fluid. For the grinding disc, h / H = 1:4 and h = 4 mm, and for the grinding pad, h' / H' = 3 / 4.

[0079] In the embodiments of this application, the hardness range of the coarse grinding pad is 90HD to 100HD, the hardness range of the fine grinding pad is 60HD to 70HD, and the hardness range of the polishing grinding pad is 35HD to 45HD, and different glass surface flatness effects can be produced by the cooperation of grinding pads 610 of different hardness.

[0080] In the embodiment of this application, the grinding pressure is 0.15 MPa, the grinding temperature is 35°C, the grinding rotation speed is 6000 rpm, and the grinding time is 140 seconds.

[0081] Surface roughness is detected using the Surtronic S-100 series surface roughness tester. The grinding effects of compound grinding pads with different hardness levels are shown in Table 1 below.

[0082] [Table 1]

[0083] Here, flatness refers to the degree of deviation between the geometric shape of the glass substrate surface and an ideal plane, and is usually expressed as the distance between two points or the radius of curvature. The flatness of high-generation TFT-LCD glass substrates has a very large impact on the strength, optical performance, physical performance, etc. of the glass substrate, so it is necessary to strictly control and detect the flatness during manufacturing. The glass scratch defect rate refers to the probability that scratches caused by surface molding and processing of semi-finished glass substrates are not completely eliminated after grinding, and the lower the glass scratch defect rate, the fewer scratches remain on the glass surface after grinding.

[0084] As can be seen from Table 1 above, when selecting rough grinding pads, fine grinding pads, and polishing pads, selecting 90HD~100HD, 60HD~70HD, and 35HD~40HD yields good performance in both flatness conformance and scratch defect rate after grinding. When selecting 90HD~95HD, 65HD~70HD, and 35HD~40HD yields even better performance in both flatness conformance and scratch defect rate after grinding.

[0085] In the embodiments of this application, the width ratio of the grinding surface 612 and the grinding groove 611 at the non-edge is set to a proportional relationship of 1:1 to 3:1, and any grinding pad that matches this proportional relationship can grind the glass substrate more effectively. Through numerous experiments and studies, the applicant has found the following:

[0086] Compared to the optimal solution, when the width ratio of the grinding surface 612 to the grinding groove 611 at the non-edge is 1:1 to 1.7:1, the flow guidance effect is excellent and the flow velocity of the grinding fluid is high, but the grinding contact area is small and the grinding efficiency is relatively low. When the width ratio of the grinding surface 612 to the grinding groove 611 at the non-edge is 1.7:1 to 2.3:1, it is possible to achieve both the flow guidance effect of the grinding fluid and grinding efficiency, thereby ensuring grinding efficiency while simultaneously reducing the likelihood of secondary defects. Compared to the optimal solution, when the width ratio of the grinding surface 612 to the grinding groove 611 at the non-edge is 2.3:1 to 3:1, the grinding efficiency is high, but the flow guidance effect is low, the fluidity of the grinding fluid is low, and secondary defects are more likely to occur.

[0087] Therefore, the test results show that when the width ratio of the grinding surface 612 to the grinding groove 611 at the non-edge is 1.7:1 to 2.3:1, as shown in Figure (2) of Figure 12, it is possible to achieve both the flow guidance effect of the grinding fluid and grinding efficiency, and better satisfy the demand for manufacturing high-quality glass substrates.

[0088] Table 2 shows the change in the rate of abrasion scratches on the glass depending on the choice between rounded and straight chamfering angles.

[0089] [Table 2] JPEG2026526119000004.jpg25170

[0090] As can be seen from the data in the table above, the chamfer angle of the grinding disc should be greater than or equal to the chamfer angle of the grinding pad. When the chamfer angle of the grinding disc is ≥ 60°, the rate of wear damage is low, and a good grinding effect is achieved.

[0091] The above embodiments are for illustrative purposes only and are not intended to limit the technical methods of the present invention. While the invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A float manufacturing process for high-generation TFT-LCD glass substrates, The process consists of a systematic combination of multiple steps. The compounding process involves selecting a raw material formulation for alkali-free aluminum borosilicate glass, weighing and mixing each raw material, and then feeding it into a melting furnace, employing a blowing or vibration method to prevent material stagnation or accumulation during feeding. The melting process employs a combined heating method of electrode melting assistance and total oxygen combustion to melt the glass compound as a molten glass liquid, A platinum channel consisting of multiple high-temperature platinum channels and one low-temperature platinum channel clarifies and homogenizes the molten glass liquid in a clarification and homogenization process, Molten glass liquid floats on the surface of tin liquid to form a continuous glass ribbon, and a molding process is performed to thin the glass ribbon as a glass substrate by adjusting the independently controlled heating unit in the solder groove and the thinning force of the micro-edge drawing machine, The annealing process involves dividing the annealing kiln into multiple areas, independently controlling the temperature of each area, and annealing the glass substrate. The process includes a grinding step in which three grinding pads with hardness ratios of 90HD-100HD, 60HD-70HD, and 35HD-40HD are sequentially used to grind and polish a glass substrate in accordance with the grinding fluid. A float manufacturing process for high-generation TFT-LCD glass substrates, characterized by the following:

2. In the blending process, the raw material formulation is 60 - 72% SiO ２ , 13 - 18% Al ２ O ３ , 8.5 - 10% B ２ O ３ , 1 - 4.5% MgO, 3 - 8% CaO, 1 - 5% SrO, 0.5 - 2% ZrO ２ , 1 - 5% P ２ O ５ , 0.1 - 0.5% SnO ２ , where SiO ２ + Al ２ O ３ is 76 - 85%, (MgO + CaO + SrO) / Al ２ O ３ is 0.4 - 0.7%, the total amount of alkaline earth metal oxides is 5 - 11.5%, B ２ O ３ / (B ２ O ３ + ZrO ２ + P ２ O ５ ) is 0.6 - 0.9%, (ZrO ２ + P ２ O ５ ) / (MgO + CaO + SrO) is 0.15 - 0.8%, the boron volatilization rate of the raw material composition is lower than 11%. Weigh the raw materials according to the above raw material formulation. When feeding, synchronously discharge the materials staying on the inner wall of the weighing bucket by the blowing of the nozzles arranged on the inner wall of the weighing bucket and the vibration of the air hammers arranged on the outer wall of the weighing bucket, and arrange a plurality of nozzles according to the deposition situation. A float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 1.

3. In the melting process, the raw material is heated and melted by electrodes provided on the inner walls and / or bottom of the melting furnace, and by an oxygen burning gun provided on the roof and / or breast wall of the melting furnace, and a foaming device and a furnace cavity are provided inside the melting furnace. A float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 1.

4. The low-temperature platinum channel includes an agitator and multiple grills. The mounting angles of adjacent grills differ, and therefore the holes on adjacent grills are misaligned. The agitation by the agitator and the turbulence from the multiple grills do not sufficiently homogenize the molten glass liquid. A float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 1.

5. In the molding process, the lateral temperature difference of the solder grooves is adjusted by controlling the output power of each lateral heating unit, and this is synchronized with the thinning force of a micro-edge drawing machine installed corresponding to the same lateral position of the heating unit, thereby thinning the glass ribbon during the molding process. A float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 1.

6. In the annealing process, ceramic rollers are used as transport rollers to convey the glass substrate, and in at least a portion of the annealing region within the annealing kiln, the temperature of the area corresponding to the edge of the glass substrate is higher than the temperature of the area corresponding to the center of the glass substrate, and the thermal conductivity of the heat-insulating material in the high-temperature layer on the inside of at least a portion of the kiln wall is lower than the thermal conductivity of the heat-insulating material in the low-temperature layer on the outside. A float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 1.

7. In the grinding process, the hardness of the coarse grinding pad, fine grinding pad, and polishing pad is selected as follows: 90HD-95HD, 60HD-70HD, and 35HD-40HD. A float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 1.

8. In the grinding process, the hardness of the coarse grinding pad, fine grinding pad, and polishing pad is selected as follows: 90HD-95HD, 65HD-70HD, and 35HD-40HD. The float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 7.

9. The grinding pad contains multiple grinding surfaces separated by grinding grooves. In addition to the grinding surface at the edge, the remaining grinding surfaces are square, and the ratio of the width of the grinding surface at the non-edge to the width of the grinding groove is between 1:1 and 3:

1. The float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 7.

10. The grinding pad is attached to the grinding disc, and chamfers are formed on all sides of the grinding disc facing the grinding pad. The grinding disc is tightly attached to all four sides of the grinding pad, and chamfers are formed on all sides of the grinding pad away from the grinding disc. The float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 9.

11. On one side of the grinding disc facing the grinding pad, rounded edges are formed in all directions, while on the other side of the grinding pad away from the grinding disc, straight chamfers are formed in all directions. The float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 10.

12. The chamfer angle of the grinding pad is less than or equal to the chamfer angle of the grinding disc. The float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 11.

13. The chamfer angle of the grinding disc is greater than or equal to the chamfer angle of the grinding pad, and the chamfer angle of the grinding disc is greater than or equal to 60°. The float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 12.

14. The chamfer angle of the grinding disc is greater than or equal to the chamfer angle of the grinding pad, and 60° ≤ the chamfer angle of the grinding disc ≤ 75°. The float manufacturing process for a high-generation TFT-LCD glass substrate according to feature 13.

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