Ultrathin flexible glass material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of ultrathin flexible glass, and particularly discloses an ultrathin flexible glass material as well as a preparation method and application thereof. The ultrathin flexible glass material comprises the following chemical components in percentage by mass: 56%-65% of SiO2, 13%-21% of Al2O3, 0-7% of B2O3, 10%-15% of Na2O, 0-5% of K2O, 1%-6% of MgO, 0-3% of BaO, 0.1%-0.5% of SnO2, 0-1.5% of Y2O3, 0-2% of ZrO2 and the balance of unavoidable impurities. And ([SiO2] + [Al2O3] + [B2O3]) / [Na2O] = 5.9 to 6.6. According to the invention, by reasonably matching the chemical components, the scratch resistance of the ultra-thin flexible glass is improved, a smaller bending radius is realized, and the ultra-thin flexible glass has higher market application value.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-thin flexible glass, and in particular to an ultra-thin flexible glass material and a preparation method and application thereof. Background Art

[0002] With the rapid development of emerging fields such as flexible electronics and wearable devices, demand for ultra-thin flexible glass is growing. Ultra-thin glass not only possesses the basic properties of glass, such as high transparency, electrical insulation, heat resistance, chemical stability, and high rigidity, but also offers advantages such as thinness, light weight, high temperature resistance, impact resistance, and no creases when bent. Therefore, it has broad application prospects in display panels, ITO conductive film glass substrates, flexible display substrates, smart surfaces, OLED lighting, and flexible solar cells.

[0003] Existing ultra-thin flexible glass has problems such as insufficient scratch resistance and limited bending radius. The surface hardness of traditional soda-lime glass or ordinary ultra-thin glass (UTG) is low (Mohs hardness ≤ 6), and it is easily scratched by hard objects such as keys and gravel, affecting the display effect and user touch; the bending radius of mainstream UTG is generally 1mm~5mm, and the number of bends is about 200,000 times, which is difficult to meet the future demand for lighter and thinner folding screen devices. Summary of the Invention

[0004] In response to the problems of insufficient scratch resistance and limited bending radius of existing ultra-thin flexible glass, the present invention provides an ultra-thin flexible glass material, a preparation method and application thereof. By rationally combining various chemical components, the scratch resistance of ultra-thin flexible glass is improved and a smaller bending radius is achieved.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is: In a first aspect, the present invention provides an ultra-thin flexible glass material comprising the following chemical components by mass: SiO2 56% to 65%, Al2O3 13% to 21%, B2O3 0.7%, Na2O 10% to 15%, K2O 0.5%, MgO 1.0% to 6%, BaO 0.3%, SnO2 0.1% to 0.5%, Y2O 30.0 to 1.5%, and ZrO 0.2%, with the remainder being unavoidable impurities. ([SiO2]+[Al2O3]+[B2O3]) / [Na2O]=5.9~6.6, where [SiO2] represents the mass content of SiO2, [Al2O3] represents the mass content of Al2O3, [B2O3] represents the mass content of B2O3, and [Na2O] represents the mass content of Na2O.

[0006] Compared with the prior art, the ultra-thin flexible glass material (referred to as glass material) provided by the present invention has SiO2 as the main network former. The structural unit of SiO2 is a tetrahedron. These tetrahedrons are interconnected by atoms at common vertices to form a three-dimensional network structure, which gives the glass material higher hardness and mechanical strength, enabling the glass material to withstand certain external forces without being easily deformed or damaged. At the same time, due to the high bond energy of the silicon-oxygen bond, the chemical stability of the glass material is greatly improved, and it has a certain resistance to chemical substances such as water, acid, and alkali. Al2O3 can combine with hydrogen ions to prevent acidic substances from corroding the glass glufosinate network, thereby enhancing the acid and water resistance of the glass material. Al2O3 can react with alkali metal ions to form more stable chemical bonds, making the network structure of the glass material tighter and stronger. When the glass material is subjected to external forces, this tight structure can better disperse stress, improve the hardness and toughness of the glass material, and thus reduce the generation and expansion of cracks. During the raw material melting process, Al2O3 and MgO can reduce the viscosity of the glass material melt, making it easier to flow and facilitating the melting, clarification and homogenization of the glass material. In the molding process, Al2O3 and MgO can increase the viscosity of the glass material melt, helping to maintain the shape of the glass material and prevent deformation. During the melting process of glass materials, the addition of B2O3 partially breaks the silicon-oxygen tetrahedral network structure. The originally tight silicon-oxygen network structure becomes relatively loose due to the intervention of boron atoms, which enables the glass material melt to achieve good fluidity at a lower temperature, which is conducive to the molding of glass materials. B2O3 can react with other components in the glass material (such as alkali metal oxides) to form more stable chemical bonds. At the same time, the boron-oxygen bond and silicon-oxygen bond have high bond energy, making the surface of the glass material less likely to react chemically with chemical substances, thereby improving the chemical stability and corrosion resistance of the glass material. B2O3, K2O, and MgO have a regulating effect on the thermal expansion coefficient of the glass material, reducing the thermal stress generated by the glass material when the temperature changes. During the melting process of silicate glass materials, Na2O and K2O will react with SiO2, destroying the SiO2 network structure and breaking the silicon-oxygen bond, thereby lowering the melting temperature of the glass material and significantly reducing the viscosity of the glass material at high temperatures, making it easier to melt, clarify, and mold. Na2O gives the surface of the glass material ion exchange strengthening properties, making the K in the molten salt + Entering into glass materials to replace Na + , forming compressive stress on the surface of the glass material, enhancing the mechanical strength of the surface of the glass material.

[0007] SiO2, Al2O3, and B2O3 form the basic skeleton of glass materials and are the core components of their structure. They are interconnected through chemical bonds to form a three-dimensional network, which provides the glass with its essential shape and stability. Na2O is a network exosome (also known as a network modifier) and does not participate in the network formation of the glass material. It resides in the network gaps, providing additional cations to the glass material and modulating its properties. This invention defines these four chemical components through a specific formula, which can further improve the hardness, strength, and thermal stability of the glass material, reduce its viscosity and melting point, and reduce its tendency to crystallize.

[0008] MgO improves the thermal conductivity and thermal expansion properties of glass, enabling faster and more even heat distribution and enhancing its resistance to thermal shock. BaO lowers the melting temperature and crystallization tendency of glass, regulating its electrical properties (including parameters such as dielectric constant and conductivity). When glass is melted, it contains numerous bubbles, which can affect its quality, such as transparency and uniformity. SnO2 decomposes into SnO and O2 at high temperatures. The resulting oxygen combines with small bubbles in the glass melt, increasing their volume and accelerating their upward and downward movement. This effectively removes bubbles from the glass, improving its clarity and transparency. Y2O3 stabilizes the crystal lattice, significantly improving the thermal shock resistance of glass, inhibiting excessive expansion and contraction during temperature fluctuations and reducing thermal stress during rapid temperature changes. Y2O3 raises the softening point of glass and forms more stable chemical bonds with other components in the glass (such as SiO2), thereby increasing its structural stability at high temperatures. Y2O3 and ZrO2 significantly increase the hardness of glass, filling the voids in the glass as a reinforcing phase, making the microstructure denser and more resistant to scratches and abrasion. Y2O3 and ZrO2 also enhance the toughness of glass. When the glass is subjected to external impact, ZrO2 undergoes a phase transition from tetragonal to monoclinic. This process absorbs energy, effectively preventing crack propagation and reducing the likelihood of breakage. Even if it does break, it will form smaller fragments, minimizing harm to the human body. ZrO2 reacts with ions in acids or bases to form a protective film that prevents further acid or base erosion of the glass.

[0009] Preferably, the ultra-thin flexible glass material includes the following chemical components by mass: SiO2 58%~64%, Al2O3 16%~20%, B2O3 2~4%, Na2O 10%~15%, K2O 1~2%, MgO 2%~4%, BaO 0~1%, SnO2 0.1%~0.5%, Y2O3 0.5~1% and ZrO2 0.2~1%, and the remainder is unavoidable impurities.

[0010] By controlling the content ranges of various chemical components, the present invention achieves improved glass material performance, reduces production complexity, and ensures product yield. Through extensive testing, the present invention has found that controlling the content of various chemical components in the glass material within the aforementioned ranges can simultaneously balance the glass material's acid resistance, water resistance, thermal expansion coefficient (i.e., thermal stability), viscosity, hardness, mechanical properties, flexibility, and processing difficulty.

[0011] Preferably, the difference between the expansion softening point Ts and the glass transition temperature Tg of the ultra-thin flexible glass material is greater than 60°C.

[0012] Further preferably, the expansion softening point Ts and the glass transition temperature Tg of the ultra-thin flexible glass material satisfy the following relationship: (Ts-Tg)≥65°C, Ts / Tg≥1.1.

[0013] In a second aspect, the present invention provides an ultra-thin flexible glass, comprising the ultra-thin flexible glass material.

[0014] Preferably, the ultimate bending radius of the ultra-thin flexible glass is ≤0.5 mm.

[0015] Preferably, the thickness of the ultra-thin flexible glass is 0.03 mm to 1.1 mm.

[0016] In a third aspect, the present invention provides a method for preparing the ultra-thin flexible glass, comprising the following steps: Weigh each raw material according to the designed mass ratio, mix and melt the raw materials, clarify and homogenize them in sequence, and produce ultra-thin flexible glass material through a down-drawing process; The ultra-thin flexible glass material is immersed in mixed molten salt at 390° C. to 430° C. for chemical strengthening to obtain the ultra-thin flexible glass.

[0017] The present invention does not make special requirements for the mixing, melting, clarification, homogenization and down-drawing processes, and can adopt the common operating steps in the field without the need for additional special equipment, thereby reducing production costs and being suitable for large-scale production or cost-sensitive applications.

[0018] The present invention uses a down-draw method to produce ultra-thin flexible glass materials with a thickness of approximately 30 μm. The two edges of the ultra-thin flexible glass material can be controlled by roller stretching and traction, with double-sided heating and cooling. The production difficulty lies in the balanced adjustment of the tension of the down-drawn molten glass and the maintenance of lateral tension in the molten glass. Uniform tension is applied to both sides of the ultra-thin flexible glass material to prevent uneven thickness due to differential shrinkage. The shaping and thickness control principles of ultra-thin flexible glass materials follow the viscosity-temperature relationship: glass viscosity varies significantly with temperature (Arrhenius equation). High temperatures and low viscosity facilitate flow, while low temperatures and high viscosity lock in shape. The final thickness is determined by adjusting the solidification position of the ultra-thin flexible glass material by adjusting the cooling rate, ensuring that the stretching process is completed while the ultra-thin flexible glass material is still plastic.

[0019] Preferably, the mixed molten salt includes potassium nitrate and cesium nitrate.

[0020] Further preferably, the mass ratio of potassium nitrate to cesium nitrate is (3.5-4.5):1.

[0021] Preferably, the chemical strengthening time is 20 min to 200 min.

[0022] In a fourth aspect, the present invention provides an application of the ultra-thin flexible glass in preparing a protective support layer for a folding screen, a flexible display substrate or a display.

[0023] The test results show that the ultra-thin flexible glass provided by the present invention has excellent scratch resistance and a smaller bending radius. The surface stress of the ultra-thin flexible glass is ≥1000MPa and the Vickers hardness is ≥670kgf / mm. 2 The maximum bending radius is ≤0.5mm, and the continuous bending times when the bending radius is 0.5mm are ≥600,000 times. It is particularly suitable for photovoltaic cells, semiconductor packaging, LED display diffusers, LED transfer media, IC circuit boards and other fields. It can be used as a protective support layer for TVs, mobile phones, tablets, laptops, foldable displays, flexible OLED displays, car displays, industrial medical equipment touch screen displays, etc. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] In the present invention, unless otherwise specified, all materials are commercially available products.

[0026] Examples 1 to 6 Examples 1 to 6 respectively provide an ultra-thin flexible glass material, the mass content of each chemical component of which is shown in Table 1.

[0027] The method for preparing the ultra-thin flexible glass material comprises the following steps: The raw materials are weighed according to the designed mass ratio, mixed and melted in turn at 1600°C, clarified at 1650°C~1670°C, homogenized at 1400°C, and then ultra-thin flexible glass materials of different thicknesses are produced through a down-draw process.

[0028] Each embodiment can produce ultra-thin flexible glass materials with thicknesses of 0.03 mm, 0.05 mm, 0.07 mm, 0.1 mm, 0.23 mm, 0.3 mm, 0.33 mm, 0.4 mm, 0.5 mm, 0.7 mm, 0.8 mm, 0.9 mm and 1.1 mm by a down-draw method.

[0029] Table 1 Mass content of each chemical component of the ultra-thin flexible glass materials of Examples 1 to 6 (%)

[0030] Comparative Examples 1 to 6 Comparative Examples 1 to 6 respectively provide an ultra-thin glass material, and the mass content of each chemical component thereof is shown in Table 2.

[0031] The method for preparing the ultra-thin glass material comprises the following steps: The raw materials are weighed according to the designed mass ratio, mixed and melted in turn at 1600℃, clarified at 1650℃~1670℃, homogenized at 1400℃, and then ultra-thin glass materials of different thicknesses are produced through a down-draw process.

[0032] Table 2 Mass content of each chemical component of the ultra-thin glass materials of Comparative Examples 1 to 6 (%)

[0033] Verification Example 1 The Young's modulus of the ultra-thin flexible glass materials of Examples 1 to 6 and the ultra-thin glass materials of Comparative Examples 1 to 6 were tested in accordance with GB / T 37780-2019 "Test method for elastic modulus, shear modulus and Poisson's ratio of glass materials". The test results are shown in Table 3. The softening points of the ultrathin flexible glass materials of Examples 1 to 6 and the ultrathin glass materials of Comparative Examples 1 to 6 were tested in accordance with GB / T 28195-2011 "Test Method for Softening Point of Glass". The test results are shown in Table 3. The annealing point and strain point of the ultra-thin flexible glass materials of Examples 1 to 6 and the ultra-thin glass materials of Comparative Examples 1 to 6 were tested in accordance with ASTM C336-71 (2020) “Standard Test Method for Annealing Point and Strain Point of Glass by Fiber Elongation”. The test results are shown in Table 3. The thermal expansion coefficients, Tg, and Ts of the ultrathin flexible glass materials of Examples 1 to 6 and the ultrathin glass materials of Comparative Examples 1 to 6 were tested in accordance with GB / T 16920-2015 “Determination of the Mean Linear Thermal Expansion Coefficient of Glass.” The test results are shown in Table 3.

[0034] Table 3 Performance test results of ultra-thin glass materials of Examples and Comparative Examples

[0035] Example 7 This embodiment provides ultra-thin flexible glasses with five thicknesses (0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm), which are respectively made from the ultra-thin flexible glass materials with thicknesses of 0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm in Example 1.

[0036] The method for preparing the above-mentioned ultra-thin flexible glass with a thickness of 0.5 mm, 0.7 mm, or 0.9 mm comprises the following steps: The ultra-thin flexible glass materials (80 mm × 40 mm in size) were immersed in a mixed molten salt at 420°C, where the mixed molten salt consisted of potassium nitrate and cesium nitrate in a mass ratio of 4:1. The materials were chemically strengthened by heat preservation for 180 minutes, cooled, and cleaned to obtain the ultra-thin flexible glass.

[0037] The method for preparing the above-mentioned 0.05 mm and 0.07 mm thick ultra-thin flexible glass comprises the following steps: The ultra-thin flexible glass materials (40 mm × 40 mm in size) were immersed in a mixed molten salt at 420°C, where the mixed molten salt consisted of potassium nitrate and cesium nitrate in a mass ratio of 4:1. The materials were chemically strengthened by heat preservation for 40 minutes, cooled, and cleaned to obtain the ultra-thin flexible glass.

[0038] Example 8 This embodiment provides ultra-thin flexible glasses with five thicknesses (0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm), which are respectively made from the ultra-thin flexible glass materials with thicknesses of 0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm of Example 2.

[0039] The method for preparing the above-mentioned ultra-thin flexible glass with a thickness of 0.5 mm, 0.7 mm, or 0.9 mm comprises the following steps: The ultra-thin flexible glass materials (80 mm × 40 mm in size) were immersed in a mixed molten salt at 430°C. The mixed molten salt consisted of potassium nitrate and cesium nitrate in a mass ratio of 3.5:1. The ultra-thin flexible glass was chemically strengthened by heat preservation for 150 minutes, and then cooled and cleaned to obtain the ultra-thin flexible glass.

[0040] The method for preparing the above-mentioned 0.05 mm and 0.07 mm thick ultra-thin flexible glass comprises the following steps: The ultra-thin flexible glass materials (size 40 mm × 40 mm) were immersed in a mixed molten salt at 430°C. The mixed molten salt consisted of potassium nitrate and cesium nitrate in a mass ratio of 3.5:1. After being kept warm for 40 minutes for chemical strengthening, the materials were cooled and cleaned to obtain the ultra-thin flexible glass.

[0041] Example 9 This embodiment provides ultra-thin flexible glasses with five thicknesses (0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm), which are respectively made from the ultra-thin flexible glass materials with thicknesses of 0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm of Example 3.

[0042] The method for preparing the above-mentioned ultra-thin flexible glass with a thickness of 0.5 mm, 0.7 mm, or 0.9 mm comprises the following steps: The ultra-thin flexible glass materials (80 mm × 40 mm in size) were immersed in a mixed molten salt at 400°C. The mixed molten salt consisted of potassium nitrate and cesium nitrate in a mass ratio of 4.5:1. After being kept warm for 180 minutes for chemical strengthening, the materials were cooled and cleaned to obtain the ultra-thin flexible glass.

[0043] The method for preparing the above-mentioned 0.05 mm and 0.07 mm thick ultra-thin flexible glass comprises the following steps: The ultra-thin flexible glass materials (40 mm x 40 mm in size) were immersed in a mixed molten salt at 400°C. The mixed molten salt consisted of potassium nitrate and cesium nitrate in a mass ratio of 4.5:1. The ultra-thin flexible glass was chemically strengthened by heat preservation for 45 minutes, and then cooled and cleaned to obtain the ultra-thin flexible glass.

[0044] Examples 10-12 Examples 10 to 12 respectively provide ultra-thin flexible glasses with five thicknesses (0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm), which are respectively made from the ultra-thin flexible glass materials with thicknesses of 0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm of Examples 4 to 6.

[0045] The preparation method of the above-mentioned ultra-thin flexible glass is the same as that in Example 7 and will not be repeated here.

[0046] Comparative Examples 6-12 Comparative Examples 6 to 12 respectively provide ultra-thin glasses of 5 thicknesses (0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm), which are respectively made from the ultra-thin glass materials of 0.05 mm, 0.07 mm, 0.5 mm, 0.7 mm, and 0.9 mm thickness of Comparative Examples 1 to 6.

[0047] The preparation method of the above ultra-thin glass is the same as that of Example 7 and will not be repeated here.

[0048] Verification Example 2 The Vickers hardness of the ultra-thin flexible glasses of Examples 7 to 12 and the ultra-thin glasses of Comparative Examples 7 to 12 was tested in accordance with GB / T 37900-2019 “Test method for hardness and fracture toughness of ultra-thin glass—Small load Vickers hardness indentation method”. The surface compressive stress CS and the depth of the ion exchange layer DOL of the ultra-thin flexible glasses of Examples 7 to 12 and the ultra-thin glasses of Comparative Examples 7 to 12 were tested using an FSM6000 surface stress meter. The test results are shown in Tables 4 and 5.

[0049] Table 4 Performance test results of ultra-thin flexible glass of the embodiment

[0050] Table 5 Performance test results of ultra-thin glass of comparative example

[0051] Examples 13 to 18 Examples 13 to 18 each provide a 0.03 mm thick ultra-thin flexible glass, which is made from the 0.03 mm thick ultra-thin flexible glass material of Examples 1 to 6.

[0052] The method for preparing the ultra-thin flexible glass comprises the following steps: The ultra-thin flexible glass materials (size 40 mm × 80 mm) were immersed in a mixed molten salt at 420°C. The mixed molten salt consisted of potassium nitrate and cesium nitrate in a mass ratio of 4:1. After being kept warm for 30 minutes for chemical strengthening, the materials were cooled and cleaned to obtain the ultra-thin flexible glass.

[0053] Comparative Examples 13-18 Comparative Examples 13 to 18 each provide an ultra-thin glass with a thickness of 0.03 mm, which is made from the ultra-thin glass material with a thickness of 0.03 mm of Comparative Examples 1 to 6.

[0054] The preparation method of the above-mentioned ultra-thin glass is the same as that of Example 13 and will not be repeated here.

[0055] Verification Example 3 The ultimate bending radius of the ultra-thin flexible glasses of Examples 13 to 18 and the ultra-thin glasses of Comparative Examples 13 to 18 was tested in accordance with GB / T 38686-2020 “Test method for flexibility of ultra-thin glass - two-point bending method”. The number of bends of the ultra-thin flexible glasses of Examples 13 to 18 at a bending radius of 0.5 mm was also tested. The test results are shown in Table 6.

[0056] Table 6 Bending performance test results of ultra-thin glass of Examples and Comparative Examples

[0057] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An ultra-thin flexible glass material, characterized in that: The chemical composition includes the following contents by mass: SiO2 56%~65%, Al2O3 13%~21%, B2O3 0~7%, Na2O 10%~15%, K2O 0~5%, MgO 1%~6%, BaO 0~3%, SnO2 0.1%~0.5%, Y2O3 0~1.5% and ZrO2 0~2%, with the balance being unavoidable impurities; ([SiO2]+[Al2O3]+[B2O3]) / [Na2O]=5.9~6.6, where [SiO2] represents the mass content of SiO2, [Al2O3] represents the mass content of Al2O3, [B2O3] represents the mass content of B2O3, and [Na2O] represents the mass content of Na2O.

2. The ultra-thin flexible glass material according to claim 1, wherein: The ultra-thin flexible glass includes the following chemical components by mass: SiO2 58%-64%, Al2O3 16%-20%, B2O3 2-4%, Na2O 10%-15%, K2O 1-2%, MgO2%-4%, BaO 0-1%, SnO2 0.1%-0.5%, Y2O3 0.5-1% and ZrO2 0.2-1%, with the remainder being unavoidable impurities.

3. The ultra-thin flexible glass material according to claim 1 or 2, characterized in that: The difference between the expansion softening point Ts and the glass transition temperature Tg of the ultra-thin flexible glass material is greater than 60°C.

4. The ultra-thin flexible glass material according to claim 3, wherein: The expansion softening point Ts and the glass transition temperature Tg of the ultra-thin flexible glass material satisfy the following relationship: (Ts-Tg)≥65°C, Ts / Tg≥1.

1.

5. An ultra-thin flexible glass, characterized in that: The ultra-thin flexible glass material comprises the ultra-thin flexible glass material according to any one of claims 1 to 4.

6. The ultra-thin flexible glass according to claim 5, wherein: The ultimate bending radius of the ultra-thin flexible glass is ≤0.5 mm.

7. The ultra-thin flexible glass according to claim 5, wherein: The thickness of the ultra-thin flexible glass is 0.03 mm to 1.1 mm.

8. The method for preparing the ultra-thin flexible glass according to any one of claims 5 to 7, characterized in that: The following steps are involved: Weigh each raw material according to the designed mass ratio, mix and melt the raw materials, clarify and homogenize them in sequence, and produce ultra-thin flexible glass material through a down-drawing process; The ultra-thin flexible glass material is immersed in mixed molten salt at 390° C. to 430° C. for chemical strengthening to obtain the ultra-thin flexible glass.

9. The method for preparing ultra-thin flexible glass according to claim 8, wherein: The mixed molten salt comprises potassium nitrate and cesium nitrate in a mass ratio of (3.5-4.5):1; The chemical strengthening time is 20 min to 200 min.

10. Use of the ultra-thin flexible glass according to any one of claims 5 to 7 in preparing a protective support layer for a folding screen, a flexible display substrate or a display.

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