Unequal-thickness flexible glass as well as tempering method and application thereof

Abstract

The invention discloses an unequal-thickness flexible glass tempering method, which comprises: preheating unequal-thickness flexible glass, immersing in a tempering reagent, taking out the unequal-thickness flexible glass, carrying out thermal insulation treatment, soaking with water, and taking out to obtain the tempered unequal-thickness flexible glass. The invention further provides the unequal-thickness flexible glass which is prepared according to the tempering method. The invention also provides an application of the unequal-thickness flexible glass. According to the method, the phenomenon of local stress concentration occurring when the unequal-thickness flexible glass is folded can be avoided, the folding performance of the unequal-thickness flexible glass is improved, meanwhile, the thickness uniformity of a groove area is optimized, and the phenomenon of wrinkles after tempering is greatly relieved, so that the service life of the ultra-thin flexible glass is greatly prolonged, the bending performance of the ultra-thin flexible glass is greatly improved, and the service life of the ultra-thin flexible glass is prolonged. And a technical foundation is laid for application and popularization of folding screens and multi-folding screens.

Description

Technical Field

[0001] The invention relates to the technical field of glass processing, and in particular to flexible glass of unequal thickness and a tempering method and application thereof. Background Art

[0002] Flexible glass is a glass material with flexibility and bendability. It is less than 100 microns thick. Unlike traditional rigid glass, it can be bent arbitrarily under the action of external force without thermal processing. This material is made through a special manufacturing process and has the advantages of both glass and plastic. It has the characteristics of ultra-thinness, wear resistance, high temperature resistance, corrosion resistance, high strength, high light transmittance, bendability and good resilience. It is used in flexible display, semiconductor, photovoltaic, automobile, medical and other fields.

[0003] With the development of flexible glass technology, flexible glass products are constantly iterating. Among them, the thickness of the bending area of ​​the flexible glass can be reduced, that is, a flexible glass structure of unequal thickness can be designed so that the bending area maintains its original excellent bending performance. At the same time, the non-bending area has a larger thickness to enhance its strength performance.

[0004] However, in the actual preparation process, the overall tempering technology in the post-process introduces new flatness problems and poor folding performance problems. The existing tempering process of flexible glass usually uses potassium nitrate molten salt as a tempering agent. After the unequal thickness flexible glass with large thickness difference undergoes potassium and sodium ion exchange in a pure potassium nitrate salt furnace, the unequal thickness area will be over-tempered, resulting in thermal expansion causing uneven force on the equal thickness area and the unequal thickness area. At this time, the unequal thickness area will not only have "wrinkles", but also further aggravate the stress concentration phenomenon, causing the unequal thickness area to be easily damaged when bent, seriously affecting the appearance and performance of the unequal thickness flexible glass.

[0005] CN115073020A discloses a chemical tempering method for ultra-thin foldable non-uniform thickness glass, wherein the non-uniform thickness glass is tempered as a whole according to the tempering process of the uniform thickness area, and the uniform thickness area surface of the tempered non-uniform thickness glass is covered with a protective film; the non-uniform thickness area of ​​the tempered non-uniform thickness glass is etched to remove the protective film of the uniform thickness area, and then the entire glass is etched to remove the light and shadow problem on the glass surface. CN113336429A discloses a chemical tempering method for ultra-thin non-uniform thickness glass, wherein the uniform thickness area surface of the non-uniform thickness glass is covered with a PET film for protection, and then the upper surface of the non-uniform thickness area of ​​the non-uniform thickness glass is coated for protection, and the coated non-uniform thickness glass is placed in a tempering molten salt for tempering. CN115331560A discloses a folding display screen and a method for manufacturing glass, wherein the non-uniform thickness flexible glass is chemically tempered n times, and mixed salt is used as a tempering agent at least once, in order to improve the problem of glass wrinkles. The above methods all use lamination, coating or multiple tempering to perform partitioning and step-by-step tempering, which increases the process steps and is very cumbersome, and is not suitable for large-scale mass production. Therefore, it is necessary to explore a simple process method that can avoid over-tempering. Summary of the invention

[0006] Based on the technical problems existing in the background technology, the present invention proposes a flexible glass of unequal thickness and a tempering method and application thereof. The method of the present invention can avoid the local stress concentration phenomenon occurring when the flexible glass of unequal thickness is folded, thereby improving its folding performance, while optimizing the thickness uniformity of the groove area, greatly alleviating the "wrinkle" phenomenon after tempering, thereby greatly improving the service life and bending performance of the ultra-thin flexible glass, and laying a technical foundation for the application and promotion of folding screens and multi-folding screens.

[0007] The invention provides a method for tempering flexible glass of unequal thickness, comprising the following steps: preheating the flexible glass of unequal thickness, immersing it in a tempering agent, then taking out the flexible glass of unequal thickness for heat preservation treatment, then soaking it in water, and taking out the tempered flexible glass of unequal thickness.

[0008] The present invention optimizes and changes the tempering method of flexible glass of unequal thicknesses, so that the flexible glass of unequal thicknesses can be fully tempered and the mechanical properties of the glass can be improved, and the glass can be prevented from staying in a potassium nitrate salt bath for a long time, which would lead to excessive tempering of the unequal thickness areas and stress concentration, resulting in easy breakage and "wrinkles" of the unequal thickness areas when bent, thereby improving the appearance and performance of the flexible glass of unequal thicknesses.

[0009] Preferably, the unequal thickness flexible glass comprises: an equal thickness area and an unequal thickness area, the thickness of the equal thickness area is 50-300 μm, and the thickness of the unequal thickness area is 20-100 μm.

[0010] Preferably, the flexible glasses of different thicknesses are placed in the tempering agent to form an angle with the liquid surface of the tempering agent and are immersed in the tempering agent.

[0011] Preferably, the angle is 70-90°.

[0012] Preferably, when adding and immersing, the angles formed by the flexible glasses of different thicknesses and the liquid surface of the tempering reagent are the same.

[0013] More preferably, the angle may be 70, 75, 80, 85 or 90°.

[0014] Since the thickness of the unequal thickness flexible glass is small and cannot be kept upright or tilted, the unequal thickness flexible glass can be placed in a fixture to keep the unequal thickness flexible glass upright or tilted; the fixture can be a stainless steel basket, etc., in which multiple pieces of unequal thickness flexible glass can be placed independently, and the above basket is a common tool in the field. When multiple pieces of glass are tempered together, space is left between each piece of glass so that each piece of glass can be covered and immersed by the tempering agent.

[0015] The present invention maintains the angle at 70-90 degrees, so that the glass surface can be evenly covered with the tempering agent, thereby avoiding the problem of uneven coverage of the tempering agent on the glass surface.

[0016] Preferably, the preheating temperature is 350-400°C.

[0017] More preferably, the preheating temperature may be 350, 355, 360, 365, 370, 375, 380, 385, 390, 395 or 400°C.

[0018] Preferably, the preheating time is 30-45 minutes.

[0019] More preferably, the preheating time may be 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44 or 45 min.

[0020] The present invention selects appropriate preheating temperature and preheating time to increase the overall temperature of flexible glasses of unequal thickness, making it easier to carry out ion exchange during subsequent tempering. At the same time, it can reduce the thermal stress generated by temperature changes in the glass during subsequent tempering and heat preservation treatment, and avoid glass breakage caused by too rapid temperature changes.

[0021] Preferably, the tempering agent is molten potassium nitrate.

[0022] The purity of the above potassium nitrate is ≥99%.

[0023] Preferably, the tempering temperature is 380-420°C.

[0024] More preferably, the tempering temperature may be 380, 385, 390, 395, 400, 405, 410, 415 or 420°C.

[0025] Preferably, the immersion in the tempering agent is 1-3 minutes.

[0026] More preferably, the immersion in the toughening agent is for 1, 1.5, 2, 2.5 or 3 minutes.

[0027] Preferably, the holding temperature is 350-500°C.

[0028] More preferably, the holding temperature may be 350, 355, 360, 365, 370, 375, 380, 385, 390, 395, 400, 405, 410, 415, 420, 425, 430, 435, 440, 445, 450, 455, 460, 465, 470, 475, 480, 485, 490, 495 or 500°C.

[0029] Preferably, the insulation time is 10-20 minutes.

[0030] More preferably, the holding time may be 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 min.

[0031] The present invention first immerses the unequal thickness flexible glass in a tempering agent for a short time for tempering, then takes it out for heat preservation treatment, and uses the tempering agent remaining on the glass surface to continue ion exchange on the glass surface, and continues tempering, which can reduce the potassium ion concentration difference between the glass surface and the interior, avoid excessive tempering of the glass in the thin area (i.e., the unequal thickness area), and eliminate the problems of light shadow and wrinkles after tempering; it can avoid that when the glass is tempered in the tempering agent, due to the excessive concentration difference, the exchange degree of sodium potassium ions is large, and at the same time, the ion exchange degree of the thick area and the thin area of ​​the unequal thickness glass is different, resulting in the problem of light shadow and wrinkles after the thin area is tempered.

[0032] Selecting the right tempering agent, appropriate temperature, immersion time, and insulation conditions can further improve the tempering effect and avoid light and shadow problems.

[0033] The above-mentioned flexible glass of different thickness can be kept in an upright or inclined state when heat preservation is performed.

[0034] Preferably, the temperature of the water is 40-60°C.

[0035] More preferably, the temperature of the water may be 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60°C.

[0036] Preferably, the soaking time is 5-10 minutes.

[0037] More preferably, the soaking time may be 5, 6, 7, 8, 9 or 10 minutes.

[0038] The present invention soaks the insulated glass in water, which can rapidly cool the glass and form a layer of compressive stress on the surface of the unequal thickness flexible glass, which can offset the tensile stress inside the glass, thereby improving the anti-breakage ability of the glass. At the same time, it can effectively avoid the uneven tempering effect caused by the glass being in a high temperature state for too long, which affects the strength and stability of the glass.

[0039] Preferably, the compressive stress layer depth of the tempered flexible glass of unequal thickness is 5-12 μm, and the compressive stress value is 400-600 MPa.

[0040] After the unequal thickness flexible glass is soaked in water, it is thinned by 1-2 μm by micro-etching to obtain the tempered unequal thickness flexible glass.

[0041] The present invention also provides a flexible glass with unequal thickness, which is manufactured according to the above-mentioned tempering method.

[0042] The present invention also proposes the application of the above-mentioned flexible glass with unequal thickness in electronic devices.

[0043] The tempering method described in the present invention has no specific size and shape restrictions on glass products, and its application includes but is not limited to electronic display screen covers such as foldable screen mobile phones and foldable screen computers.

[0044] Beneficial effects:

[0045] 1. The tempering method of the present invention avoids complicated operations such as film coating, film tearing, and zone tempering, has simple steps, and can be realized by adjusting the automation program on the basis of existing flexible glass tempering equipment, which is more feasible and mass-producible in actual production;

[0046] 2. The tempering method of the present invention can reduce the potassium ion concentration difference between the surface and the interior of the glass, and avoid excessive tempering of the glass with different thickness areas in the tempering agent, resulting in poor light and shadow effects "wrinkles";

[0047] 3. The present invention uses a single molten potassium nitrate as a tempering agent, which reduces the proportioning work compared to mixed salt tempering agents, and can also reduce the types and amounts of reagents, making it more convenient in actual production; during the tempering process, appropriate process parameters are adjusted to ensure that the stress value of the glass meets the requirements.

[0048] 4. The tempered flexible glass of unequal thickness produced by the present invention can smoothly pass the 2PB test with a smaller bending radius, the staggered bending test, and the dynamic bending test, and has good impact resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 These are photos of the tempered flexible glasses of unequal thickness obtained in Example 2 and Comparative Example 1, wherein a is Comparative Example 1 and b is Example 2. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is described in detail below through specific embodiments.

[0051] Example 1

[0052] A method for tempering flexible glass of unequal thickness comprises the following steps:

[0053] The unequal thickness flexible glass includes: an equal thickness area and an unequal thickness area, the thickness of the equal thickness area is 150 μm, and the thickness of the unequal thickness area is 30 μm;

[0054] Insert the flexible glasses of different thicknesses into the stainless steel baskets one by one, and then gently place them in the charging basket of the tempering furnace; then transfer them to the high-temperature preheating furnace and preheat them at 390℃ for 30 minutes;

[0055] Then transfer to a salt furnace at 420°C, adjust the angle between the flexible glass surface of unequal thickness and the liquid surface of the tempering agent (i.e., molten potassium nitrate) to 70°, then add to the tempering agent and immerse for 3 minutes (when adding and immersing, the angle formed by the flexible glass surface of unequal thickness and the liquid surface of the tempering agent is the same), so that the tempering agent evenly covers the glass surface; then transfer to the preheating furnace again, and temper at 420°C for 15 minutes;

[0056] Then transfer to pure water at 50°C and soak for 5 minutes, and take out to obtain the tempered flexible glass of unequal thickness.

[0057] Example 2

[0058] A method for tempering flexible glass of unequal thickness comprises the following steps:

[0059] The unequal thickness flexible glass includes: an equal thickness area and an unequal thickness area, the thickness of the equal thickness area is 70 μm, and the thickness of the unequal thickness area is 30 μm;

[0060] Insert the flexible glasses of different thicknesses into the stainless steel baskets one by one, and then gently place them in the charging basket of the tempering furnace; then transfer them to the high-temperature preheating furnace and preheat them at 380℃ for 30 minutes;

[0061] Then transfer to a salt furnace at 400°C, adjust the angle between the flexible glass surface of unequal thickness and the liquid surface of the tempering agent (i.e., molten potassium nitrate) to 90°, then add it into the tempering agent and immerse it for 1 minute (when adding and immersing, the angle formed by the flexible glass surface of unequal thickness and the liquid surface of the tempering agent is the same), so that the tempering agent evenly covers the glass surface; then transfer it back to the preheating furnace and temper it at 400°C for 15 minutes;

[0062] Then transfer to pure water at 50°C and soak for 5 minutes, and take out to obtain the tempered flexible glass of unequal thickness.

[0063] Comparative Example 1

[0064] A method for tempering flexible glass of unequal thickness comprises the following steps:

[0065] The unequal thickness flexible glass includes: an equal thickness area and an unequal thickness area, the thickness of the equal thickness area is 70 μm, and the thickness of the unequal thickness area is 30 μm;

[0066] Insert the flexible glasses of different thicknesses into the stainless steel baskets one by one, and then gently place them in the charging basket of the tempering furnace; then transfer them to the high-temperature preheating furnace and preheat them at 380℃ for 30 minutes;

[0067] Then transfer to a salt furnace at 400°C, adjust the angle between the flexible glass surface of unequal thickness and the liquid surface of the tempering agent (i.e., molten potassium nitrate) to 90°, and then add it into the tempering agent and immerse it for 15 minutes (when adding and immersing, the angle formed by the flexible glass surface of unequal thickness and the liquid surface of the tempering agent is the same);

[0068] Then transfer to pure water at 50°C and soak for 5 minutes, and take out to obtain the tempered flexible glass of unequal thickness.

[0069] The tempered flexible glasses of different thicknesses prepared in Examples 1-2 and Comparative Example 1 were subjected to pickling and micro-etching to reduce the thickness by 1.5 μm under the same conditions, and then the properties of the flexible glasses of different thicknesses were tested. The results are shown in Table 1. Figure 1 shown.

[0070] Figure 1 These are photos of the tempered flexible glasses of unequal thickness obtained in Example 2 and Comparative Example 1, wherein a is Comparative Example 1 and b is Example 2.

[0071] Depend on Figure 1 It can be seen that the tempering method of the present invention can significantly improve the problem of wrinkles easily appearing on flexible glasses of unequal thicknesses after tempering.

[0072] Table 1 Test results

[0073]

[0074] Note: The thick area in Table 1 is the equal thickness area, and the thin area is the unequal thickness area.

[0075] The detection method for extreme bending is the two-point bending method of GB / T 38686-2020 Ultra-thin glass flexibility test method.

[0076] It can be seen from Table 1 that the thin area of ​​the unequal thickness flexible glass treated by the tempering method of the present invention has good bending performance, while still maintaining high impact resistance in both the thick area and the thin area, which can meet the performance requirements of users for flexible glass.

[0077] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for tempering flexible glass of unequal thickness, characterized in that: The method comprises the following steps: preheating the unequal thickness flexible glass, immersing the glass in a tempering agent, taking out the unequal thickness flexible glass for heat preservation, soaking the glass in water, and taking out the tempered unequal thickness flexible glass.

2. The method for tempering flexible glass of unequal thickness according to claim 1, characterized in that: The unequal thickness flexible glass comprises: an equal thickness area and an unequal thickness area, the thickness of the equal thickness area is 50-300 μm, and the thickness of the unequal thickness area is 20-100 μm.

3. The method for tempering flexible glass of unequal thickness according to claim 1 or 2, characterized in that: The unequal thickness flexible glass is added to and immersed in the tempering reagent to form an angle with the liquid surface of the tempering reagent; preferably, the angle is 70-90°; preferably, when added and immersed, the unequal thickness flexible glass forms the same angle with the liquid surface of the tempering reagent.

4. The method for tempering flexible glass of unequal thickness according to any one of claims 1 to 3, characterized in that: The preheating temperature is 350-400°C; preferably, the preheating time is 30-45 minutes.

5. The method for tempering flexible glass of unequal thickness according to any one of claims 1 to 4, characterized in that: The tempering agent is molten potassium nitrate; preferably, the tempering temperature is 380-420° C.; preferably, the immersion in the tempering agent is 1-3 minutes.

6. The method for tempering flexible glass of unequal thickness according to any one of claims 1 to 5, characterized in that: The holding temperature is 350-500°C; preferably, the holding time is 10-20 minutes.

7. The method for tempering flexible glass of unequal thickness according to any one of claims 1 to 6, characterized in that: The temperature of the water is 40-60°C; preferably, the soaking time is 5-10 minutes.

8. The method for tempering flexible glass of unequal thickness according to any one of claims 1 to 7, characterized in that: The compressive stress layer depth of the tempered flexible glass of varying thickness is 5-12 μm, and the compressive stress value is 400-600 MPa.

9. A flexible glass of unequal thickness, characterized in that: It is prepared according to the tempering method according to any one of claims 1 to 8.

10. Use of the flexible glass of unequal thickness as claimed in claim 9 in electronic devices.

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