Ultra-thin glass and method of making, strengthened ultra-thin glass, polished strengthened ultra-thin glass and applications

Abstract

The application provides an ultrathin glass and a preparation method, a strengthened ultrathin glass, a polished strengthened ultrathin glass and application. The ultrathin glass has a balanced and stable glass network and a dynamic balance between network solidification ability and ion mobility before being strengthened, thereby providing a good-performance substrate for the strengthened ultrathin glass and the polished strengthened ultrathin glass with high CS and good bending performance.

Description

Technical Field

[0001] This application relates to the field of glass materials technology, and in particular to an ultrathin glass and its preparation method, a strengthened ultrathin glass, a polished strengthened ultrathin glass, and its applications. Background Technology

[0002] The commercial application of flexible display technology places extreme demands on the bending performance and reliability of ultra-thin glass (UTG). An ideal UTG cover glass not only needs to remain intact at extremely small bending radii, but also needs to maintain stable performance through hundreds of thousands of dynamic bends, that is, to have excellent bending limits and bending stability.

[0003] As is known to those skilled in the art, higher surface compressive stress (CS) is crucial for the performance of UTG: first, a high CS layer can effectively constrain the propagation of surface microcracks, thereby improving the glass's impact resistance and static strength; second, when the glass is bent, a high CS layer can partially offset or reduce the maximum tensile stress borne by the outermost surface, which theoretically helps to achieve a smaller bending radius.

[0004] However, in practice, a significant technical contradiction exists in this field: simply pursuing a high CS value does not always translate into good bending performance, especially bending stability. Existing UTG products, even if they pass the initial bending test, exhibit significant performance variability and low yield in long-term cyclic testing. Summary of the Invention

[0005] The purpose of this application is to provide an ultrathin glass and its preparation method, a strengthened ultrathin glass, a polished strengthened ultrathin glass, and its application. The ultrathin glass has a balanced and stable glass network before strengthening, and the network solidification ability and ion mobility are in dynamic equilibrium. This provides a high-performance substrate for strengthening and polishing to obtain strengthened ultrathin glass with high CS and good bending performance.

[0006] In a first aspect, this application provides an ultrathin glass comprising the following components, by mass percentage of oxides: SiO2: 56 wt%~64 wt%; Al2O3: 16.5 wt%~21.5 wt%; ZrO2: 0.5 wt%~3 wt%; Na2O: 15 wt%~20 wt%; K2O: 0 wt%~3.0 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.3<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.6.

[0007] Furthermore, in some embodiments of this application, the thickness of the ultrathin glass is 0.02~0.4mm, preferably 0.03~0.3mm.

[0008] Furthermore, in some embodiments of this application, the arithmetic mean roughness (Ra) of the surface of the ultrathin glass is <0.5 nm, preferably <0.4 nm; and / or The total thickness deviation of the ultrathin glass is ≤4μm, preferably ≤2μm.

[0009] Furthermore, in some embodiments of this application, the ultrathin glass, with a thickness of 0.02~0.4mm, has an optical transmittance of ≥91.0% and a haze of <0.2% at 550nm.

[0010] Furthermore, in some embodiments of this application, the serration depth h of the edge of the ultrathin glass is ≤10μm, and the ratio h / d of the depth h and width d of the serration defect at the edge is <1.4.

[0011] Furthermore, in some embodiments of this application, the surface of the ultrathin glass is formed using a one-time molding process.

[0012] Secondly, this application also provides a method for preparing the ultrathin glass described in the first aspect, wherein the raw materials for preparing the glass are mixed, melted, and then ultrathin glass is obtained through a one-time molding process and annealing.

[0013] Furthermore, in some embodiments of this application, the one-time forming process is selected from any one of narrow-slit drawing, overflow drawing, secondary thinning, and float glass processes.

[0014] Furthermore, in some embodiments of this application, the ultrathin glass further includes a cutting process and an edge etching treatment, wherein the cutting process is selected from wheel cutting or laser cutting.

[0015] Thirdly, this application also provides a reinforced ultrathin glass, the reinforced ultrathin glass comprising a tensile stress layer and compressive stress layers located on both sides of the tensile stress layer, the thickness of each compressive stress layer not exceeding 0.3 times the thickness t of the reinforced ultrathin glass; The central region of the tensile stress layer comprises the following components, based on the mass percentage of oxides: SiO2: 56.0%~64.0 wt%; Al2O3: 16.5 wt%~21.5 wt%; ZrO2: 0.5 wt%~3.0 wt%; Na2O: 15.0 wt%~20.0 wt%; K2O: 0.0 wt%~3.0 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.30<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.60.

[0016] Furthermore, in some embodiments of this application, the thickness t of the reinforced ultrathin glass is 0.02-0.40 mm; and / or The surface roughness (Ra) of the reinforced ultrathin glass is <0.5 nm, preferably <0.4 nm; and / or The serrated depth h of the edge of the reinforced ultrathin glass is ≤10μm, and the ratio h / d of the depth h to the width d is <1.4.

[0017] Furthermore, in some embodiments of this application, the depth DOL of each compressive stress layer of the reinforced ultrathin glass is 0.1t < DOL < 0.3t.

[0018] Furthermore, in some embodiments of this application, the surface compressive stress CS of the reinforced ultrathin glass is ≥900MPa.

[0019] Furthermore, in some embodiments of this application, the reinforced ultrathin glass is obtained by strengthening ultrathin glass prepared by the preparation method of the ultrathin glass described in the first aspect or the ultrathin glass described in the third aspect.

[0020] Furthermore, in some embodiments of this application, the strengthening is a single-step chemical strengthening.

[0021] Furthermore, in some embodiments of this application, the salt used in the enhanced salt bath includes 0-0.30 wt% lithium salt, 0-5 wt% sodium salt, and 95-100 wt% potassium salt; and / or The strengthening temperature is 350~500℃; and / or The strengthening time is 5~240 min.

[0022] Fourthly, this application also provides a polished and strengthened ultrathin glass, which includes a tensile stress layer and compressive stress layers located on both sides of the tensile stress layer. The thickness of each compressive stress layer is less than 0.3 times the thickness t of the polished and strengthened ultrathin glass and more than 0.1 times the thickness t of the polished and strengthened ultrathin glass. The central region of the tensile stress layer comprises the following components, based on the mass percentage of oxides: SiO2: 56.0 wt%~64.0 wt%; Al2O3: 16.5 wt%~21.5 wt%; ZrO2: 0.5 wt%~3.0 wt%; Na2O: 15.0 wt%~20.0 wt%; K2O: 0.0 wt%~3.0 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.30<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.60.

[0023] Furthermore, in some embodiments of this application, when the thickness of the polished and strengthened ultrathin glass is 0.02~0.4mm, its optical transmittance at a wavelength of 550nm is ≥ 91%.

[0024] Furthermore, in some embodiments of this application, the surface compressive stress CS of the polished and strengthened ultrathin glass is ≥750MPa.

[0025] Furthermore, in some embodiments of this application, the surface compressive stress CS, the surface compressive stress layer depth DOL, and the bending coefficient BR of the polished and strengthened ultrathin glass satisfy the following relationships (3) to (4): (3) BR= (CS*DOL*(1000t-DOL)) / 1000t (4) 100*1000t + 500 < BR < 125*1000t + 1750; Among them, the unit of surface compressive stress CS is MPa, the unit of compressive stress layer depth DOL is μm, and the unit of glass thickness t is μm; and / or The surface roughness (Ra) of the polished and strengthened ultrathin glass is <0.5 nm, preferably <0.4 nm; and / or The serration depth h of the edge of the polished and strengthened ultrathin glass is ≤10μm, and the ratio of the depth h to the width d is h / d <1.4.

[0026] Furthermore, in some embodiments of this application, the in-plane stress difference (C) of the polished and strengthened ultrathin glass is... SIPSD <50 MPa.

[0027] Furthermore, in some embodiments of this application, when the thickness of the polished and strengthened ultrathin glass is 0.03~0.05mm, the average pen drop height is >9.5cm.

[0028] Furthermore, in some embodiments of this application, when the thickness of the polished and strengthened ultrathin glass is 0.03~0.05mm, the ultimate bending radius R1 < 1.0mm, the ultimate slip bending radius R2 < 1.5mm, and the ultimate dynamic bending radius R3 < 1.5mm.

[0029] Furthermore, in some embodiments of this application, when the thickness of the polished and strengthened ultrathin glass is 0.03 mm, the yield rate of misalignment bending with a misalignment bending radius of 0.7 mm is >90%; and / or When the thickness of the polished and strengthened ultrathin glass is 0.05mm, the yield rate of misalignment bending is >90% when the misalignment bending radius is 1.1mm.

[0030] Furthermore, in some embodiments of this application, the polished and strengthened ultrathin glass is obtained by strengthening and polishing the ultrathin glass described in the first aspect, or by strengthening and polishing the ultrathin glass prepared by the method described in the second aspect, or by polishing the strengthened ultrathin glass described in the third aspect.

[0031] Furthermore, in some embodiments of this application, the strengthening is a single-step chemical strengthening, and the regional temperature fluctuation of the salt bath used for the strengthening is ≤2°C; and / or The polishing is chemical polishing, the polishing depth t1 is 1μm < t1 < 2.5μm, and the polishing rate v1 is 0.2μm / min < v1 < 1μm / min.

[0032] Fifthly, this application also provides the application of the ultra-thin glass described in the first aspect or the ultra-thin glass prepared by the method described in the second aspect, or the reinforced ultra-thin glass described in the third aspect, or the polished reinforced ultra-thin glass described in the fourth aspect, in the field of electronic products.

[0033] Sixthly, this application also provides a flexible folding device, comprising the ultrathin glass described in the first aspect or the ultrathin glass prepared by the method described in the second aspect, or the reinforced ultrathin glass described in the third aspect, or the polished reinforced ultrathin glass described in the fourth aspect.

[0034] The beneficial effects of this application are: 1. This application provides an ultrathin glass that employs a specific glass composition based on oxides and controls the compositional relationships between specific components such as silicon oxide, aluminum oxide, zirconium oxide, sodium oxide, potassium oxide, and magnesium oxide. This results in an ultrathin glass substrate with a glass network structure exhibiting an "open / dense" balance, which is beneficial for storing high elastic strain energy while allowing Na+ to... + / K + Effective ion exchange is achieved to provide a corresponding ultrathin glass substrate for obtaining high surface compressive stress in the subsequently strengthened glass. At the same time, the network stability and ion mobility of the glass network structure formed by the ultrathin glass are well balanced, providing sufficient ion exchange rate and depth for the subsequent strengthening of the ultrathin glass, while ensuring that the relaxation rate of the strengthened compressive stress layer is slow and the stress state is stable, providing substrate support for maintaining its long-term flexible bending performance.

[0035] 2. This application also provides a reinforced ultrathin glass, which is obtained by strengthening a glass substrate with a specific glass network structure. It has a specific compressive stress layer thickness, and within the thickness range of 0.02~0.4mm, its surface compressive stress can reach more than 900 MPa, providing material support for the long-term retention of high pressure stress strength and flexible bending performance of polished reinforced ultrathin glass.

[0036] 3. This application also provides a polished and strengthened ultrathin glass, which is obtained by strengthening and polishing a glass substrate with a specific glass network structure. Its appearance geometric quality is stable and uniform, and its internal stress distribution is balanced. It has a light transmittance of more than 91% and a compressive stress strength of more than 750MPa. Under these conditions, it also has an extremely small bending radius and ultra-high bending stability, which makes its bending performance stable and its fatigue life extended. This gives the flexible folding device based on it good fatigue resistance, and provides support for improving the service life and yield of the flexible folding device. Attached Figure Description

[0037] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the test method for the average pen drop height of the glass sample or the comparison sample in this application; Among them, 1-1: pen, 1-2: pen impact height, 1-3: reinforced ultra-thin glass with double-sided OCA+PET film, 1-4: 304 stainless steel plate. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In this application, surface compressive stress (CS) refers to the compressive stress value of the compressive stress layer formed on the glass surface after chemical strengthening and subsequent ion exchange treatment. For ion exchange treatment, ion exchange is performed on the glass surface, forming a surface layer with residual compressive stress, which is the compressive stress layer. Specifically, it refers to the compressive stress layer at the glass transition temperature T. g At the following temperatures, metal ions with small ionic radii (typically Li ions and Na ions) on the glass surface are replaced by ions with larger ionic radii (typically Na ions or K ions relative to Li ions, and K ions relative to Na ions) through ion exchange.

[0041] In this application, the compressive stress depth (DOL) is the thickness of the glass surface layer where ion exchange occurs during the chemical strengthening process, i.e., the thickness of the compressive stress layer.

[0042] In this application, the in-plane stress difference (C) SIPSD This refers to the dispersion of surface compressive stress values ​​at multiple measurement points within a specific area on the surface of a chemically strengthened and polished ultrathin glass (UTG) product. Specifically, it is quantified by the absolute difference between the maximum and minimum surface compressive stress values ​​at each measurement point within the area. The calculation method is as follows: C SIPSD = |max(CS1,CS2,…,CS) 9) min(CS1,CS2,…,CS9)∣ Where CS1, CS2, ..., CS9 represent the surface compressive stress values ​​(unit: MPa) at the nine measurement points, and max and min represent the maximum and minimum values ​​of these stress values, respectively.

[0043] In this application, optical transmittance refers to the ratio of the radiant energy projected onto and transmitted through an object to the total radiant energy projected onto the object during the process of incident light flux from the incident surface or the incident surface of the medium to the other side.

[0044] Test method: 1. Stress testing In this application, the FSM-6000 instrument is used to test the CS and C of the glass sample under test. SIPSD And DOL, where the refractive index was set to 1.51 and the photoelastic coefficient was set to 28.6 during the test.

[0045] 2.C SIPSD test The measurement points are arranged in a nine-point configuration, meaning that nine representative measurement points are selected within the effective surface area of ​​the glass sample to be tested, either in a uniform distribution or based on a specific grid (3×3 matrix). The surface compressive stress (CS) value at each measurement point should be measured using a standard surface stress meter (such as a polarimeter based on refractive index changes), and the measurement conditions should be consistent (e.g., temperature 23°C ± 2°C, humidity 50% ± 5%).

[0046] 3. Thickness test In this application, the thickness was obtained using a digital micrometer Mitutoyo 406-250-30 or a laser thickness gauge.

[0047] 4. Optical performance testing In this application, the transmittance of the glass samples under test is tested using a haze meter in accordance with the national standard GB / T 7962.12-2010 "Test Methods for Colorless Optical Glass - Part 12: Internal Spectral Transmittance". Specifically, the transmittance of five glass samples from the same batch to different wavelengths of light is tested using a haze meter. The average transmittance of the five glass samples under 550nm wavelength light is taken as the transmittance result of the glass sample under 550nm wavelength light.

[0048] The haze meter used in the test of this invention is a Konica Minolta CM-3600A spectrophotometer from Japan. The light receiving optical system is transmission, the spectral dispersive method is a planar refracting grating, the wavelength range is 360nm~740nm, the wavelength spacing is 10nm, the illumination source is a pulsed xenon lamp X4, the ambient temperature of the instrument is 24℃, and the air humidity is 40%.

[0049] 5. Roughness test The surface roughness Ra of the glass sample under test was measured using a UKC ER-230 white light interferometer.

[0050] 6. Edge chipping test In this application, a field emission scanning electron microscope (Zeiss Sigma 360) was used to magnify the edge tooth depth of the glass sample under test at 200x magnification.

[0051] 7. Edge morphology test In this application, a field emission scanning electron microscope (Zeiss Sigma 360) was used to test the edge morphology of the glass sample under test at 50x magnification.

[0052] 8. Limit bending radius test Cover both sides of the glass sample to be tested with a 30um PE soft film, ensuring there are no obvious air bubbles or foreign objects. Start the ultimate bending test machine (HT-320HX-U) and press down at a speed of 0.5mm / s until the glass sample breaks. Record the radius at the time of breakage.

[0053] 9. Offset Bending Test Cover both sides of the glass sample to be tested with a 50µm PE film, ensuring there are no obvious bubbles or foreign objects. Place the UTG with the PE film inside the bending plate, and then start the kinetic bending tester (HT-380PFC-U) to press down to a radius of R0.7 (30µm glass) and R1.1 (50µm glass). Move the platform with a kinetic range of 7mm each time, and perform two kinetic passes to the left and right. The platform moving speed is 600mm / min. After the kinetic test is completed, remove the glass sample to be tested and repeat the kinetic test in the opposite direction.

[0054] 10. Dynamic bending test Cover both sides of the glass sample to be tested with a 50um PE soft film. The surface should be free of obvious bubbles and foreign matter. Use double-sided tape to fix the glass sample to be tested onto the bending fixture or platform. There should be no bulges at the bonding position. Set the required bending radius and the bending speed to 60 cycles / min. Then start the dynamic bending test machine (SMC-700PF-4FC) and set the number of bending cycles to 200,000. The glass sample to be tested should not break.

[0055] 11. Average Pen Impact Height Test In this application, a 12.6g Chenguang pen was used to test the pen impact height 1-1. The pen impact height 1-2 was obtained according to the method in group standard T / CSTM 00409-2021. Before testing the pen impact height, a 50μm PE film + a 50μm OCA film was applied to the first and second surfaces of the glass sample to be tested using a roller press, resulting in a double-sided OCA+PET film-coated glass sample 1-3. The average pen impact height of five film-coated glass samples was taken as the average pen impact height of the glass sample to be tested. See reference [link to relevant documentation]. Figure 1 The base plate is made of 304 stainless steel plate 1-4. The average impact height of the pen drop measured from 5 coated glass samples is taken as the average impact height of the glass sample under test. (Refer to...) Figure 1 .

[0056] 12. Determination of the mass percentage of the glass composition in this application The composition of the glass in this application was determined by X-ray fluorescence spectrometry (XRF). The testing equipment was a Thermo Fisher Scientific ARL PERFORM'X wavelength dispersive X-ray fluorescence spectrometer with a tube voltage of 40 kW, a current of 60 mA, a collimator of 0.15, a LiF200 crystal, an FPC detector, a 29 mm circle for the testing range, and a sample size of 50*50 mm. The fluorescence intensity was calculated using the standard curve method to obtain the mass percentage content of each analyte.

[0057] Bending failure of ultrathin glass is one of the challenges in its application to flexible folding devices. In existing research, the applicant found that bending failure often does not originate from the macroscopic structure of the glass, but rather from its microscopic stress concentration points. These stress concentration points are mainly induced by the following factors: 1. Microscopic inhomogeneity in appearance geometry: Microscopic defects inherent in the glass substrate, such as thickness variations (TTV), surface roughness, and edge treatment (e.g., the size of chipped edges after laser cutting, and the aspect ratio of serrated defects), can create an uneven stress field during chemical strengthening. Under high CS conditions, this stress inhomogeneity is amplified dramatically, generating localized tensile stresses at the tips of microscopic defects that far exceed the material's bearing capacity. This becomes the starting point for crack initiation, leading to unstable bending performance and a sharp drop in fatigue life.

[0058] 2. Uneven Stress Distribution: Existing strengthening processes often focus on increasing CS (Compressive Stress Layer) while neglecting the optimal ratio between CS and Depth of Os (DOL). A stress profile with high CS but mismatched DOL will cause the transition region between the compressive stress layer and the central tensile stress layer to become steep when the glass is bent, exacerbating the stress gradient and reducing the overall toughness and fatigue resistance of the glass.

[0059] Therefore, the problems with existing technologies can be summarized as follows: they fail to systematically coordinate the advantages of "high CS" with microstructure control and macro-stress design to ensure "bending stability." The industry either sacrifices CS for stability, resulting in insufficient impact resistance; or blindly pursues high CS while neglecting the control of micro-defects and stress ratios, leading to bending life and yield that cannot meet commercial requirements. Based on this, this application proposes an ultrathin glass substrate using specific components and specific component blends to obtain a specific "open / dense" balance and a dynamic balance between "network stability and ion mobility" glass network structure. This provides a material basis for subsequent strengthening to obtain polished and strengthened ultrathin glass with high impact resistance, high pressure stress strength, high yield, and high fatigue resistance.

[0060] In a first aspect, this application provides an ultrathin glass comprising the following components, by mass percentage of oxides: SiO2: 56.0 wt%~64.0 wt%; Al2O3: 16.5 wt%~21.5 wt%; ZrO2: 0.5 wt%~3.0 wt%; Na2O: 15.0 wt%~20.0 wt%; K2O: 0.0 wt%~3.0 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.30<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.60.

[0061] In the glass system of this application, SiO2 serves as the basic component of the glass network structure. Appropriately increasing its content can enhance the glass's stability and mechanical strength; however, excessive content will significantly increase melt viscosity and deteriorate melting and forming performance. In some embodiments of this application, the SiO2 content, based on the mass percentage of oxides, is 56.0 wt% to 64.0 wt%, preferably 59.0 wt% to 63.0 wt%. In some embodiments of this application, the SiO2 content, based on the mass percentage of oxides, can be: 56.0 wt%, 56.5 wt%, 57 wt%, 57.5 wt%, 58.00 wt%, 58.50 wt%, 59.00 wt%, 59.50 wt%, 60.00 wt%, 60.50 wt%, 61.00 wt%, 61.50 wt%, 62.00 wt%, 62.50 wt%, 63.00 wt%, 63.50 wt%, or 64.00 wt%, etc., as well as all ranges and subranges between the above values. It should be understood that, in the implementation plan, any of the above scopes can be combined with any other scopes.

[0062] In the glass system of this application, Al2O3 is mainly used to construct and reinforce the glass network framework. Simultaneously, the ion exchange rate can be controlled by adjusting the spatial dimensions available for ion exchange within the glass network. Because the ultrathin glass involved in this application requires extremely high bending strength, the amount of Al2O3 needs to be controlled within a specific range. If the Al2O3 content is too high, the melting and operating temperatures of the glass will increase significantly, easily causing crystallization and affecting the transparency and flexibility of the glass; conversely, if the Al2O3 content is too low, the chemical stability and mechanical properties of the glass will decrease. In some embodiments of this application, the Al2O3 content, by mass percentage of oxides, is 16.5 wt% to 21.5 wt%, preferably 17.0 wt% to 21.0 wt%. In some embodiments of this application, the Al2O3 content, by mass percentage of the oxide, can be: 16.50 wt%, 17.00 wt%, 17.50 wt%, 18.00 wt%, 18.50 wt%, 19.00 wt%, 19.50 wt%, 20.00 wt%, 20.50 wt%, 21.00 wt%, or 21.50 wt%, etc., and all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0063] In the glass system of this application, ZrO2 is an intermediate oxide in glass formation. Appropriate addition can improve chemical stability, hardness, and scratch / drop resistance. Its high charge and strong electric field characteristics have an accumulation effect on the glass structure, and appropriate addition can enhance the strengthening stress. Therefore, in some embodiments of this application, the ZrO2 content in the ultrathin glass is 0.5 wt% to 3.0 wt%, preferably 0.8 wt% to 2.0 wt%, based on the mass percentage of the oxide. In some embodiments of this application, the ZrO2 content, by percentage of oxide, can be 0.50 wt%, 0.60 wt%, 0.70 wt%, 0.80 wt%, 0.90 wt%, 1.00 wt%, 1.10 wt%, 1.20 wt%, 1.30 wt%, 1.40 wt%, 1.50 wt%, 1.60 wt%, 1.70 wt%, 1.80 wt%, 1.90 wt%, 2.00 wt%, 2.10 wt%, 2.20 wt%, 2.30 wt%, 2.40 wt%, 2.50 wt%, 2.60 wt%, 2.70 wt%, 2.80 wt%, 2.90 wt%, or 3.00 wt%, etc., and all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0064] In the glass system of this application, Na₂O, as an external oxide of the network, provides free oxygen, increasing the oxygen-silicon ratio in the glass structure, thereby effectively regulating the glass viscosity and promoting the melting and refining processes. Simultaneously, it enhances Na–K ion exchange in the glass, contributing to higher surface compressive stress (CS). However, if the Na₂O content is too high, it weakens the glass network structure, leading to decreased stability, increased coefficient of thermal expansion, and consequently, exacerbated glass warping. In some embodiments of this application, the Na₂O content, by mass percentage of the oxide, is 15.0 wt%-20.0 wt%, preferably 15.0 wt% to 19.0 wt%. In some embodiments of this application, the Na₂O content, by percentage of the oxide, can be 15.00 wt%, 15.50 wt%, 16.00 wt%, 16.50 wt%, 17.00 wt%, 18.50 wt%, 19.00 wt%, 19.50 wt%, or 20.00 wt%, etc., and all ranges and subranges between these values. It should be understood that, in the implementation plan, any of the above scopes can be combined with any other scopes.

[0065] In the glass system of this application, K2O is an oxide on the glass network and is an optional component. Adding an appropriate amount provides free oxygen and increases the oxygen-silicon ratio; excessive addition damages the network structure and degrades optical properties, stress enhancement, chemical stability, mechanical strength, and weather resistance. Therefore, in some embodiments of this application, the K2O content in the impact-resistant ultrathin glass, based on the mass percentage of the oxide, is 0.0 wt% to 3.0 wt%, preferably 0.0 wt% to 2.0 wt%. In some embodiments of this application, the content of Na2OK2O, based on the percentage of the oxide, can be 0.00 wt%, 0.20 wt%, 0.40 wt%, 0.60 wt%, 0.80 wt%, 1.00 wt%, 1.20 wt%, 1.40 wt%, 1.60 wt%, 1.80 wt%, 2.00 wt%, 2.20 wt%, 2.40 wt%, 2.60 wt%, 2.80 wt%, or 3.00 wt%, etc., and all ranges and subranges between the above values. It should be understood that, in the implementation plan, any of the above scopes can be combined with any other scopes.

[0066] In the glass system of this application, MgO is an essential component, reducing the high-temperature viscosity of the glass and improving its melting and one-time forming properties. It also increases the elastic modulus and hardness of the glass, enhancing its mechanical strength. An appropriate amount of MgO helps stabilize the glass network and provides charge compensation through synergistic effects with Al2O3; however, excessive MgO may lead to an increased tendency for crystallization. During chemical strengthening, MgO affects Na+. + Diffusion: An appropriate amount of MgO can optimize stress distribution and improve stress uniformity and stability, but excessive amounts will hinder ion exchange, reduce the depth of the compressive stress layer, and decrease surface compressive stress. In some embodiments of this application, the MgO content, based on the mass percentage of the oxide, is 0.5 wt%-2.9 wt%, preferably 1.5-2.9%. In some embodiments of this application, the MgO content, based on the mass percentage of the oxide, can be: 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 1.00 wt%, 1.10 wt%, 1.30 wt%, 1.50 wt%, 1.70 wt%, 1.90 wt%, 2.30 wt%, 2.50 wt%, 2.70 wt%, or 2.90 wt%, etc., and all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0067] In the glass system of this application, not only must the content of each component fall within the above-mentioned range, but the inventors also unexpectedly discovered that the amount of specific components must also satisfy the above-mentioned formulas (1) to (2). This is because the glass network structure of the ultrathin glass provided in this application needs to achieve a balance between "open / dense" and "network stability and ion mobility". The applicant found that when the components of Al2O3, MgO, Na2O, ZrO2, K2O, and SiO2 in the glass system of this application satisfy the relationship shown in formula (1), the glass network is in an "optimal equilibrium state", making the network sufficiently dense to store high elastic strain energy (high CS), but not too dense, allowing Na + / K + Effective ion exchange is achieved. This ensures that the chemical strengthening process can stably obtain the highest surface compressive stress. If the ratio is too low (<0.31): the network is too "open" or weakened. The ion exchange rate may be fast, but the stress relaxation is also fast, making it difficult to form a stable high CS layer. The overall hardness of the glass may also be insufficient. If the ratio is too high (>0.37): the network is too "rigid". The ion exchange kinetics are hindered, and ions are difficult to diffuse. Extremely high strengthening temperature or time is required, and there may be a risk of microcracks due to excessive network elasticity. Similarly, the optimal CS cannot be obtained. At the same time, when the components of Al2O3, MgO, ZrO2, Na2O, and K2O in the glass system of this application satisfy the relationship shown in Equation (2), the network curing ability and ion mobility of the glass network reach a dynamic balance. This ensures both sufficient ion exchange rate and depth (DOL) and a slow relaxation rate and stable stress state of the formed stress layer. If the ratio is too high (>1.6): the network is "over-cured". The denominator (alkali metal) is relatively too small, or the molecule (curing agent) is too large. This leads to insufficient exchangeable ion sources, a decrease in the chemical driving force of ion exchange, and consequently, a lower CS value. Even if the network can store high elasticity, there is insufficient ion exchange to "inject" this energy. If the ratio is too low (<1.3), the network is "overly open." Ion exchange driving force is strong, and diffusion is rapid. CS may rise rapidly in the initial stage of enhancement. However, due to the insufficient stability of the network structure, the injected stress will relax quickly, especially at operating or ambient temperatures. CS will decay significantly over time, resulting in poor product reliability.

[0068] Equation (1) measures the "open / dense" balance of the glass network structure. When the ratio is within the ideal window of 0.31-0.37, the glass network is in an "optimal equilibrium state." In Equation (2), the numerator represents the "network solidification capability," and the denominator represents the "ion mobility and exchange driving force source." The ratio is essentially the "counter-index of network stability and ion mobility." When the ratio is within the ideal window of 1.3-1.6, the network solidification capability and ion mobility reach a dynamic balance. Therefore, satisfying the relationships shown in Equations (1) and (2) within a specific composition range can ensure that the network structure of the obtained ultrathin glass reaches the required excellent range in both the "open / dense" balance and the dynamic balance of "network stability and ion mobility," providing the network structure support of the substrate for subsequent strengthening and polishing to obtain the required high-pressure stress strength, high impact resistance, and high bending fatigue resistance of ultrathin flexible glass.

[0069] A clarifying agent may also be added to the composition of the impact-resistant ultrathin glass of this application. Examples of clarifying agents commonly used in the art include SnO2, Sb2O3, and NaCl. In some embodiments of this application, the amount of clarifying agent added is 0.01 to 1.00 wt% of the glass mass.

[0070] In some embodiments of this application, the thickness of the ultrathin glass is 0.02-0.4 mm, preferably 0.03-0.3 mm. The thickness of the ultrathin glass can be adjusted within the range of 0.02-0.4 mm according to the application requirements, such as 0.4 mm, 0.3 mm, 0.2 mm, 0.1 mm, 0.09 mm, 0.08 mm, 0.07 mm, 0.06 mm, 0.05 mm, 0.04 mm, 0.03 mm, or 0.02 mm, as well as all ranges and sub-ranges between these values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range. Furthermore, the glass conforming to the above composition provided in this application can also be manufactured into electronic devices with a thickness greater than 0.4 mm for application.

[0071] In some embodiments of this application, the arithmetic mean roughness (Ra) of the surface of the ultrathin glass is <0.5 nm, preferably <0.4 nm.

[0072] In some embodiments of this application, the total thickness deviation of the ultrathin glass is ≤4μm, preferably ≤2μm.

[0073] The surface Ra of the ultrathin glass is preferably controlled within 0.5 nm (excluding 0.5 nm) and its total thickness deviation is controlled within 4.0 μm. This can further reduce the microscopic defects of the ultrathin glass, avoid the formation of an uneven stress field during the subsequent strengthening process, reduce the possibility of cracks in the obtained polished and strengthened ultrathin glass under high pressure stress, improve the performance stability of the obtained polished and strengthened ultrathin glass when bent, and provide substrate support for optimizing the yield of staggered bending and dynamic bending performance of polished and strengthened ultrathin glass.

[0074] In some embodiments of this application, because polished and strengthened ultrathin glass has corresponding size requirements and processing requirements such as strengthening and polishing during application, the ultrathin glass usually needs to be cut into ultrathin glass sheets of the required size after forming. During the cutting process, the edges formed by the cutting will produce micro-defects such as edge chipping defects and serration defects formed by the cutting tool. These defects can also easily form an uneven stress field during the subsequent strengthening process, causing the polished and strengthened ultrathin glass to crack under high pressure stress. Based on this, if the ultrathin glass provided in this application needs to be cut, the edges formed by the cutting are etched after cutting to control the serration depth h of the ultrathin glass edge to be ≤10μm, and the ratio h / d of the serration defect depth h to the width d of the edge to be <1.4, so as to reduce the impact of micro-defects such as edge chipping or serration defects formed by the cutting tool on the service life of the subsequent polished and strengthened ultrathin glass. Preferably, the serration depth h of the ultrathin glass edge is ≤5μm, and the ratio h / d of the serration defect depth h to the width d of the edge to be <1.3. This is because the serrated defects formed by cutting (depth h > 10 μm) are not only stress concentration sources, but may also contain microcrack networks. In the high-temperature (e.g., 350-450℃) and high-concentration salt bath environment of subsequent strengthening treatments, these microcracks will rapidly propagate due to thermal stress or the volume expansion effect of ion exchange. Therefore, controlling the serrated defects within the range of ≤10 μm and controlling e within the range of h ≤ 5 μm can control the initial defect size below the "subcritical crack propagation threshold" of the glass material, so that even if residual stress exists, the defect cannot propagate stably. In addition, the stress concentration factor at the defect depends not only on the defect depth h, but also on its geometry (especially the aspect ratio h / d). When h / d ≥ 1.4, the defect exhibits a "deep and narrow" sharp crack morphology with an extremely small radius of curvature at the tip, resulting in an exponential increase in local tensile stress, which easily induces crack initiation and propagation under high-pressure stress layers. Therefore, this application etches the edges to achieve a post-cut h / d ratio of <1.4, thus regulating the defect morphology into a shallow and wide, relatively smooth pit, significantly reducing the stress concentration factor. Further optimization, with h / d <1.3, reduces the stress concentration level to near the baseline state of a defect-free edge, thereby completely blocking the path of crack nucleation at the defect during the strengthening process. This application, by limiting the tooth depth h and its ratio h / d to the width, synergistically suppresses the adverse effects of the cutting edge on the strengthening process and bending performance from both defect size and geometric morphology dimensions.

[0075] In some embodiments of this application, the ultrathin glass, with a thickness of 0.02~0.40 mm, has an optical transmittance of ≥91.0% and a haze of <0.2% at 550 nm. The ultrathin glass provided by this application, with its high light transmittance and low haze at 550 nm, provides a substrate basis for the polished and strengthened ultrathin glass with high optical transmittance at 550 nm, formed after strengthening and polishing. Preferably, the ultrathin glass, with a thickness of 0.02~0.4 mm, has an optical transmittance of ≥91.5% and a haze of <0.1% at 550 nm.

[0076] Secondly, this application provides a method for preparing ultrathin glass as described above, comprising the following steps: The raw materials for glass preparation are mixed, melted, and then ultrathin glass is obtained through a one-step molding process.

[0077] The mixing process involves mixing the raw materials used to prepare glass in a container using existing mixing methods, such as stirring. The stirring speed and the temperature and atmosphere during the stirring process are the same as those in existing glass preparation processes, such as room temperature and air environment. Appropriate heating can also be carried out during the mixing process.

[0078] During the melting process, the temperature is controlled within the range of 1400℃ to 1700℃, and the melting time is 4h to 240h. In some embodiments of this application, the melting temperature can be 1400℃, 1450℃, 1500℃, 1550℃, 1600℃, 1650℃, or 1700℃, as well as all ranges and sub-ranges between these values. In some embodiments of this application, the melting time can be 4h, 16h, 32h, 64h, 120h, or 240h, as well as all ranges and sub-ranges between these values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0079] In the annealing process, the formed glass is conveyed into an annealing furnace. The glass enters the annealing furnace at a temperature of 700°C to 1000°C and is continuously cooled. Upon reaching the furnace outlet, the glass temperature is reduced to 200°C to 350°C, and no heat preservation treatment is performed during the cooling process. The annealing time is controlled between 20 seconds and 10 minutes. In some embodiments of this application, the starting temperature of the annealing process can be 700°C, 750°C, 800°C, 850°C, 900°C, or 950°C, or any range and sub-range between these values. The ending temperature of the annealing process can be 220°C, 250°C, 270°C, 300°C, 315°C, or 330°C, or any range and sub-range between these values. In some embodiments of this application, the annealing time can be 30 seconds, 1 minute, 2 minutes, 3 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, or 9 minutes, or any range and sub-range between these values. It should be understood that, in the implementation plan, any of the above scopes can be combined with any other scopes.

[0080] In the preparation method of this application, the one-time molding process can be any of the existing one-time glass molding processes, such as narrow-slit down-drawing, overflow down-drawing, secondary thinning method and float glass process.

[0081] The preparation method of this application may also include a cutting process and a polishing process for ultra-thin glass, that is, cutting the formed ultra-thin glass into ultra-thin glass sheets of the required size, and then performing edge etching on the edge surface formed by the cutting to form the required surface. The cutting process can be wheel cutting or laser cutting.

[0082] The one-time molding process, cutting process and polishing process used for the ultra-thin glass are all existing technologies, and therefore will not be described in detail in this application.

[0083] Thirdly, this application provides a reinforced ultrathin glass, which includes a tensile stress layer and compressive stress layers located on both sides of the tensile stress layer, wherein the thickness of each compressive stress layer does not exceed 0.3 times the thickness t of the reinforced ultrathin glass. The central region of the tensile stress layer comprises the following components, based on the mass percentage of oxides: SiO2: 56 wt%~64 wt%; Al2O3: 16.5 wt%~21.5 wt%; ZrO2: 0.5 wt%~3 wt%; Na2O: 15 wt%~20 wt%; K2O: 0 wt%~3 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.3<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.6 This strengthened ultrathin glass can be obtained by strengthening the aforementioned ultrathin glass. Chemical strengthening is an ion exchange process that occurs only on the surface of the impact-resistant ultrathin glass. After strengthening, a compressive stress layer with a thickness within 0.3 times the thickness of the ultrathin glass is formed on both sides of the ultrathin glass. This ensures that the surface compressive stress can reach no less than 900 MPa when the thickness of the strengthened ultrathin glass is no more than 0.02-0.40 mm. Therefore, the glass composition of the tensile stress layer at the center of the strengthened ultrathin glass, based on the mass percentage of oxides, is the same as that of the ultrathin glass, and will not be described in detail here.

[0084] In glass systems for strengthening ultrathin glass, SiO2 serves as a fundamental component of the glass network structure. Appropriately increasing its content can enhance glass stability and mechanical strength; however, excessive content will significantly increase melt viscosity and deteriorate melting and forming performance. In some embodiments of this application, the SiO2 content, based on the mass percentage of oxides, is 56.0 wt% to 66.0 wt%, preferably 59.0 wt% to 63.0 wt%. In some embodiments of this application, the SiO2 content, based on the mass percentage of the oxide, can be: 56.0 wt%, 56.5 wt%, 57.0 wt%, 57.5 wt%, 58.00 wt%, 58.50 wt%, 59.00 wt%, 59.50 wt%, 60.00 wt%, 60.50 wt%, 61.00 wt%, 61.50 wt%, 62.00 wt%, 62.50 wt%, 63.00 wt%, 63.50 wt%, or 64.00 wt%, etc., and all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0085] In the glass system for strengthening ultrathin glass, Al2O3 is mainly used to construct and reinforce the glass network framework. Simultaneously, the ion exchange rate can be controlled by adjusting the space size available for ion exchange within the glass network. Since the ultrathin glass involved in this application requires extremely high bending strength, the amount of Al2O3 needs to be controlled within a specific range. If the Al2O3 content is too high, the melting and operating temperatures of the glass will increase significantly, easily causing crystallization and affecting the transparency and flexibility of the glass; conversely, if the Al2O3 content is too low, the chemical stability and mechanical properties of the glass will decrease. In some embodiments of this application, the Al2O3 content, by mass percentage of oxides, is 16.5wt-21.5wt%, preferably 17.0-21.0wt%. In some embodiments of this application, the Al2O3 content, by percentage of oxides, can be: 16.50 wt%, 17.00 wt%, 17.50 wt%, 18.00 wt%, 18.50 wt%, 19.00 wt%, 19.50 wt%, 20.00 wt%, 20.50 wt%, 21.00 wt%, or 21.50 wt%, etc., and all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0086] In the glass system for strengthening ultrathin glass, ZrO2 is an intermediate oxide in glass formation. Adding an appropriate amount can improve chemical stability, hardness, and scratch / drop resistance. Its high charge and strong electric field characteristics have an accumulation effect on the glass structure, and adding an appropriate amount can increase the strengthening stress. Therefore, in some embodiments of this application, the ZrO2 content in the ultrathin glass is 0.5wt%-3.0wt%, preferably 0.8-2.0wt%, based on the mass percentage of the oxide. In some embodiments of this application, the ZrO2 content, by mass percentage of the oxide, can be 0.50 wt%, 0.60 wt%, 0.70 wt%, 0.80 wt%, 0.90 wt%, 1.00 wt%, 1.10 wt%, 1.20 wt%, 1.30 wt%, 1.40 wt%, 1.50 wt%, 1.60 wt%, 1.70 wt%, 1.80 wt%, 1.90 wt%, 2.00 wt%, 2.10 wt%, 2.20 wt%, 2.30 wt%, 2.40 wt%, 2.50 wt%, 2.60 wt%, 2.70 wt%, 2.80 wt%, 2.90 wt%, or 3.00 wt%, etc., and all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0087] In glass systems for strengthening ultrathin glass, Na₂O, as an external oxide in the network, provides free oxygen, increasing the oxygen-silicon ratio in the glass structure, thereby effectively regulating glass viscosity and promoting melting and refining processes. Simultaneously, it enhances Na–K ion exchange in the glass, contributing to higher surface compressive stress (CS). However, excessive Na₂O content weakens the glass's network structure, leading to decreased stability, increased coefficient of thermal expansion, and consequently, exacerbated glass warping. In some embodiments of this application, the Na₂O content, by mass percentage of the oxide, is 15.00 wt%-20.00 wt%, preferably 15.00~19.00 wt%. In some embodiments of this application, the Na₂O content, by percentage of the oxide, can be 15.00 wt%, 15.50 wt%, 16.00 wt%, 16.50 wt%, 17.00 wt%, 18.50 wt%, 19.00 wt%, 19.50 wt%, or 20.00 wt%, etc., and all ranges and subranges between these values. It should be understood that, in the implementation plan, any of the above scopes can be combined with any other scopes.

[0088] In the glass system for strengthening ultrathin glass, K2O is an oxide on the outer layer of the glass network and is an optional component. Adding an appropriate amount provides free oxygen and increases the oxygen-silicon ratio; excessive addition damages the network structure and degrades optical properties, strengthening stress, chemical stability, mechanical strength, and weather resistance. Therefore, in some embodiments of this application, the K2O content in the impact-resistant ultrathin glass, based on the mass percentage of the oxide, is 0.0wt% to 3.0wt%, preferably 0.0% to 2.0wt%. In some embodiments of this application, the K2O content, based on the mass percentage of the oxide, can be 0.00wt%, 0.20wt%, 0.40wt%, 0.60wt%, 0.80wt%, 1.00wt%, 1.20wt%, 1.40wt%, 1.60wt%, 1.80wt%, 2.00wt%, 2.20wt%, 2.40wt%, 2.60wt%, 2.80wt%, or 3.00wt%, etc., and all ranges and subranges between the above values. It should be understood that, in the implementation plan, any of the above scopes can be combined with any other scopes.

[0089] In glass systems for strengthening ultrathin glass, MgO is an essential component, reducing the high-temperature viscosity of the glass and improving melting and one-time forming performance. It also increases the elastic modulus and hardness of the glass, enhancing its mechanical strength. Appropriate amounts of MgO help stabilize the glass network and provide charge compensation through synergistic effects with Al₂O₃; however, excessive MgO may lead to an increased tendency for crystallization. During chemical strengthening, MgO affects the Na₂O content. +Diffusion: An appropriate amount of MgO can optimize stress distribution and improve stress uniformity and stability, but excessive amounts will hinder ion exchange, reduce the compressive stress layer depth and surface compressive stress. In some embodiments of this application, the MgO content, based on the mass percentage of oxides, is 0.5wt%-2.9wt%, preferably 1.5-2.9wt%. In some embodiments of this application, the MgO content, based on the mass percentage of oxides, can be: 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 1.00wt%, 1.10wt%, 1.30wt%, 1.50wt%, 1.70wt%, 1.90wt%, 2.30wt%, 2.50wt%, 2.70wt%, or 2.90wt%, etc., and all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0090] In the glass system for strengthening ultrathin glass, not only must the content of each component fall within the above-mentioned range, but the inventors also unexpectedly discovered that the amount of specific components must also satisfy the above-mentioned formulas (1) to (2), so that the glass network structure of the strengthened ultrathin glass provided in this application needs to achieve a balance between "open / dense" and "network stability and ion mobility". The applicant found that when the components of Al2O3, MgO, Na2O, ZrO2, K2O, and SiO2 in the glass system of strengthened ultrathin glass satisfy the relationship shown in formula (1), the glass network is in an "optimal equilibrium state", making the network dense enough to store high elastic strain energy (high CS), but not too dense, allowing Na to be beneficial to the strengthening process. + / K +Effective ion exchange is achieved. This ensures that the chemical strengthening process can stably obtain the highest surface compressive stress. If the ratio is too low (<0.31): the network is too "open" or weak. The ion exchange rate may be fast, but the stress relaxation is also fast, making it difficult to form a stable high CS layer. The overall hardness of the glass may also be insufficient. If the ratio is too high (>0.37): the network is too "rigid". Ion exchange kinetics are hindered, ions are difficult to diffuse, extremely high strengthening temperature or time is required, and there is a risk of microcracks due to excessive network elasticity, which also makes it impossible to obtain the optimal CS. At the same time, when the composition of Al2O3, MgO, ZrO2, Na2O, and K2O in the glass system of the strengthened ultrathin glass satisfies the relationship shown in Equation (2), the network solidification ability and ion mobility of the glass network reach a dynamic balance. This ensures both sufficient ion exchange rate and depth (DOL) and a slow relaxation rate and stable stress state of the formed stress layer. If the ratio is too high (>1.6): the network is "over-cured". If the denominator (alkali metal) is too small, or the molecule (curing agent) is too large, this leads to insufficient exchangeable ion sources, a decrease in the chemical driving force of ion exchange, and consequently, a lower CS value. Even if the network can store high elastic energy, there is insufficient ion exchange to "inject" this energy. If the ratio is too low (<1.3), the network is "overly open." The ion exchange driving force is strong, and diffusion is rapid. CS may rise rapidly in the initial stage of strengthening. However, due to the insufficient stability of the network structure, the injected stress will relax quickly (rapid relaxation), especially at operating or ambient temperatures. CS will decay significantly over time, resulting in poor product reliability.

[0091] Equation (1) measures the "open / dense" balance of the glass network structure. When the ratio is within the ideal window of 0.31-0.37, the glass network is in an "optimal equilibrium state." In Equation (2), the numerator represents the "network solidification capability," and the denominator represents the "ion mobility and exchange driving force source." The ratio is essentially the "counter-index of network stability and ion mobility." When the ratio is within the ideal window of 1.3-1.6, the network solidification capability and ion mobility reach a dynamic balance. Therefore, satisfying the relationships shown in Equations (1) and (2) within a specific composition range can ensure that the network structure of the obtained ultrathin glass reaches the required excellent range in both the "open / dense" balance and the dynamic balance of "network stability and ion mobility," providing glass network structure support for the polishing process to obtain ultrathin flexible glass with the required high pressure stress strength, high impact resistance, and high bending fatigue resistance.

[0092] In some embodiments of this application, the thickness of the ultrathin glass is 0.02-0.4 mm, preferably 0.03-0.3 mm. The thickness of the ultrathin glass can be adjusted within the range of 0.02-0.4 mm according to the application requirements, such as 0.4 mm, 0.3 mm, 0.2 mm, 0.1 mm, 0.09 mm, 0.08 mm, 0.07 mm, 0.06 mm, 0.05 mm, 0.04 mm, 0.03 mm, or 0.02 mm, as well as all ranges and sub-ranges between these values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range. Furthermore, the glass conforming to the above composition provided in this application can also be manufactured into electronic devices with a thickness greater than 0.4 mm for application.

[0093] In some embodiments of this application, the arithmetic mean roughness (Ra) of the surface of the reinforced ultrathin glass is <0.5 nm, preferably <0.4 nm.

[0094] In some embodiments of this application, the total thickness deviation of the reinforced ultrathin glass is ≤4μm, preferably ≤2μm.

[0095] The surface Ra of the reinforced ultrathin glass is preferably controlled within 0.5 nm (excluding 0.5 nm) and its total thickness deviation is controlled within 4 μm. This can further reduce the microscopic defects of the reinforced ultrathin glass, avoid the formation of an uneven stress field during the subsequent polishing process, reduce the possibility of cracks in the obtained polished reinforced ultrathin glass under high pressure stress, and provide substrate support for the bending performance stability of the polished reinforced ultrathin glass.

[0096] A clarifying agent may also be added to the composition of the strengthened ultrathin glass of this application. Examples of clarifying agents commonly used in the art include SnO2, Sb2O3, and NaCl. In some embodiments of this application, the amount of clarifying agent added is 0.01 to 1 wt% of the glass mass.

[0097] In this application, the strengthening process of the ultrathin glass is a single-step chemical strengthening process, specifically: a salt bath is performed using a salt comprising 0~0.30wt% lithium salt, 0~5wt% sodium salt, and 95~100wt% potassium salt; the salt bath temperature is 350~500℃, and the salt bath time is 5~240min.

[0098] Preferably, the salt bath temperature is 350~410℃, more preferably 390℃. Preferably, the salt bath time is 8~120min, more preferably 10~70min.

[0099] Fourthly, this application provides a polished and strengthened ultrathin glass, the polished and strengthened ultrathin glass comprising a tensile stress layer and compressive stress layers located on both sides of the tensile stress layer, the thickness of each compressive stress layer being less than 0.3 times the thickness t of the polished and strengthened ultrathin glass and greater than 0.1 times the thickness t of the polished and strengthened ultrathin glass; The central region of the tensile stress layer comprises the following components, based on the mass percentage of oxides: SiO2: 56 wt%~64 wt%; Al2O3: 16.5 wt%~21.5 wt%; ZrO2: 0.5 wt%~3 wt%; Na2O: 15 wt%~20 wt%; K2O: 0 wt%~3 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.3<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.6.

[0100] The polished and strengthened ultrathin glass can be obtained by strengthening and polishing the aforementioned ultrathin glass, or by polishing the aforementioned strengthened ultrathin glass. The strengthening and polishing steps occur only on the surface of the ultrathin glass body. After strengthening, a compressive stress layer with a thickness within 0.3 times the thickness of the ultrathin glass is formed on both sides of the ultrathin glass. The polishing step involves polishing the surface of the strengthened ultrathin glass to remove surface defects and passivate microcracks introduced by chemical strengthening. Simultaneously, the surface compressive stress CS, surface compressive stress layer depth DOL, and bending coefficient (BR) of the obtained polished and strengthened ultrathin glass meet the requirements for its application. The surface compressive stress of the polished and strengthened ultrathin glass can reach at least 750 MPa when the thickness of the polished and strengthened ultrathin glass is not more than 0.02-0.40 mm. At a thickness of 0.02-0.4 mm, the optical transmittance of the polished and strengthened ultrathin glass at 550 nm is ≥91%. The surface compressive stress CS, surface compressive stress layer depth DOL, and bending coefficient (BR) of the polished and strengthened ultrathin glass simultaneously satisfy the following relationship: (1) CS≥750MPa (2) 0.1t < DOL < 0.3t (3) BR= (CS*DOL*(1000t-DOL)) / 1000t (4) 100*1000t + 500 < BR < 125*1000t + 1750; Furthermore, the in-plane stress difference (CSIPSD) of the polished and strengthened ultrathin glass can be controlled to be <50MPa, thereby achieving good bending performance and impact resistance: at a thickness of 0.03~0.05mm, the average pen drop height of the polished and strengthened ultrathin glass is >9.5cm; when the thickness of the polished and strengthened ultrathin glass is 0.03~0.05mm, the ultimate bending radius R1 is <1.0mm, the ultimate misaligned bending radius R2 is <1.5mm, and the ultimate dynamic bending radius R3 is <1.5mm; when the thickness of the polished and strengthened ultrathin glass is 0.03mm, the misaligned bending yield is >90% when the misaligned bending radius is 0.7mm; when the thickness of the polished and strengthened ultrathin glass is 0.05mm, the misaligned bending yield is >90% when the misaligned bending radius is 1.1mm.

[0101] Since the polished and strengthened ultrathin glass can be obtained by strengthening and polishing the aforementioned ultrathin glass, chemical strengthening is an ion exchange process that occurs only on the surface of the ultrathin glass body. After strengthening, a compressive stress layer with a thickness within 0.3 times the thickness of the ultrathin glass is formed on both sides of the ultrathin glass. Polishing, on the other hand, is a surface treatment of the strengthened ultrathin glass and does not affect the composition of the tensile stress layer at its center. Therefore, the glass composition of the tensile stress layer at the center of the polished and strengthened ultrathin glass, in terms of the mass percentage of oxides, is the same as the glass composition of the ultrathin glass, and therefore will not be described in detail.

[0102] It should also be noted that when the polished and strengthened ultrathin glass provided in this application is obtained from the above-mentioned ultrathin glass or strengthened ultrathin glass with a thickness of 0.02~0.4mm, its thickness is reduced, but the polishing depth is controlled as much as possible within 1μm < t1 < 2.5μm. Therefore, its actual thickness is approximately equal to 0.02~0.4mm, rather than being absolutely equal to the thickness of ultrathin glass or strengthened ultrathin glass with a thickness of 0.02~0.4mm.

[0103] Therefore, the composition of the tensile stress layer at the center of the polished and strengthened ultrathin glass, in terms of the mass percentage of oxides, also satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.3<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.6.

[0104] Furthermore, the polishing process used in the polished and strengthened ultrathin glass provided in this application is chemical polishing. The etching solution used in the chemical polishing includes one or more of hydrofluoric acid, nitric acid, hydrochloric acid, sulfuric acid, and ammonium fluoride. By mass percentage, the etching solution includes 0.1-2% hydrofluoric acid, 0-2% nitric acid, 0-2% sulfuric acid, 0-1% hydrochloric acid, 0-1% ammonium fluoride, and the balance being water. The etching time is 60-1200s, and the etching temperature is 20-40℃. Preferably, the etching solution includes 0.5-1.5% hydrofluoric acid, 0-1.5% nitric acid, 0-1.5% sulfuric acid, 0-0.8% hydrochloric acid, 0-0.8% ammonium fluoride, and the balance being water. The etching time is 90-600s, and the etching temperature is 21-25℃.

[0105] To control the in-plane stress difference (CSIPSD) of the strengthened and polished ultrathin glass to be less than 50 MPa, the applicant found that during the strengthening process of the ultrathin glass, the temperature fluctuation of the salt bath used for strengthening should be ≤2℃. Furthermore, during polishing, the depth of chemical polishing should be controlled as much as possible within 1μm < t1 < 2.5μm, and the polishing rate should be as low as 0.2μm / min < v1 < 1μm / min. This is because when the salt bath temperature fluctuation is greater than 2℃, according to the Arrhenius equation, even a small temperature change will significantly alter the ion exchange rate, and the temperature difference leads to different degrees of exchange in different areas of the glass. This increases the CS difference within the sheet, resulting in stress high and low points, reducing overall strength and reliability. It is prone to failure due to uneven stress during subsequent processing or bending. The purpose of polishing is twofold: first, to remove surface defects and passivate microcracks; and second, to regulate and optimize the stress distribution on the surface. However, when the etching and polishing rate is too slow (<0.2μm / min), the total process time (t = etching amount / rate) becomes too long. During excessively long etching processes, the effects of minute temperature field drifts within the etching tank, gradients in solution concentration due to evaporation or reaction, and minor fluctuations such as environmental vibrations are amplified over time, transforming into an uncontrollable and random spatial distribution of material removal rate. This results in non-uniform exposure of the underlying CS layer, introducing random, unpredictable, and uncompensated CS differences. When the etching rate is too fast (>0.9 μm / min), this excessively fast rate typically relies on a high concentration of etching solution, leading to a violent reaction. This causes the etching to shift from isotropic to anisotropic, preferentially attacking weak points in the glass surface microstructure (such as impurity phases, microcrack tips, and loose areas of the network structure), forming "etch pits." This selective etching rapidly disrupts the microscopic continuity of the CS layer, causing drastic fluctuations in CS at the microscale. Macroscopically, this manifests as a significant decrease in the average CS value, while local CS differences (in-plane stress differences) increase, severely impairing the fatigue strength and optical uniformity of polished and strengthened ultrathin glass.

[0106] Fifthly, this application provides an application of the ultra-thin glass as described above, or the ultra-thin glass prepared by the above method, or the strengthened ultra-thin glass as described above, or the polished strengthened ultra-thin glass as described above, in the field of flexible folding devices; particularly its application on the display screen of flexible folding devices, such as its application on foldable mobile phone displays and curved computer displays.

[0107] Furthermore, the applications also include applications in the aerospace field, serving as a protective encapsulation layer for flexible solar panels or photovoltaic modules; applications also include applications in the automotive display field, serving as a display carrier for automotive sliding and rolling screens or AR-HUDs; applications also include applications in the semiconductor field, serving as a glass substrate for chip packaging or a touch sensor for under-display fingerprint modules; applications also include applications in the smart healthcare field, serving as a base material for electronic skin patches; and applications also include applications in the high-end acoustics field, serving as a support layer for speaker diaphragms.

[0108] Sixthly, this application also provides a flexible folding device; the flexible folding device includes the ultra-thin glass described above, or the ultra-thin glass prepared by the method described above, or the strengthened ultra-thin glass described above, or the polished strengthened ultra-thin glass described above. The ultra-thin glass, or the ultra-thin glass prepared by the method described above, or the strengthened ultra-thin glass described above, or the polished strengthened ultra-thin glass described above, can be applied to its display screen or glass cover, and the flexible folding device can be at least one of foldable mobile phones, foldable tablet computers, foldable handheld game consoles, foldable portable digital devices, foldable vehicle central control systems, and foldable electronic whiteboard glass.

[0109] Furthermore, this application also provides an aerospace photovoltaic module, an in-vehicle intelligent display terminal, a semiconductor packaging structure, a smart medical patch, or a high-end acoustic device; the aerospace photovoltaic module includes the ultra-thin glass described above, which serves as an encapsulation layer for a flexible solar panel; the in-vehicle intelligent display terminal includes the ultra-thin glass described above, which serves as a cover plate for an in-vehicle sliding and rolling AMOLED central control screen or an anti-reflective window for an AR-HUD; the semiconductor packaging structure includes the ultra-thin glass described above, which serves as a glass through-hole substrate for chip packaging; the smart medical patch includes the ultra-thin glass described above, which serves as a flexible substrate for electronic skin; the high-end acoustic device includes the ultra-thin glass described above, which serves as a rigid support layer for a speaker diaphragm.

[0110] To facilitate a better understanding of the innovative aspects of this application by those skilled in the art, the technical solutions of this application are further described in detail below with reference to embodiments. The embodiments of this application described in detail below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0111] Example 1 This embodiment provides a method for preparing ultrathin glass, which specifically includes the following steps: (1) According to the formula of Example 1 in Table 1, each raw material component was accurately weighed according to the proportion and thoroughly mixed to obtain a mixture. The mixture was heated to 1650℃ to melt and melted for 10 hours. Then, a glass substrate with a size of 500mm*400mm was prepared by the pull-down method. Then, it was annealed at 750℃ for 5 minutes. Then, ultra-thin glass samples with sizes of 140*70*0.03mm and 140*70*0.05mm were cut out. Then, the samples were subjected to edge etching treatment to eliminate and passivate the micro-cracks on the edges.

[0112] (2) The ultrathin glass obtained in step (1) is subjected to single-step chemical strengthening to obtain a strengthened ultrathin glass sample; (3) The surface of the reinforced ultrathin glass sample is chemically polished; then the ultrathin glass sample after the above polishing treatment is ultrasonically cleaned to obtain the polished reinforced ultrathin glass sample to be tested.

[0113] Examples 2-9 Examples 2 through 9 were operated under the same conditions as Example 1, except that the raw material composition of the ultrathin glass was provided according to the formulations shown in Table 1 for Examples 2 through 9, and the ultrathin glass samples were cut into corresponding sizes according to the same preparation steps; and the preparation process parameters, strengthening and polishing processes were provided according to the melting temperature, time, annealing temperature, time, strengthening temperature, strengthening time, polishing temperature, polishing time, polishing rate and polishing etching solution formulations shown in Tables 1 and 2 for Examples 2 through 9.

[0114] Comparative Examples 1 to 17 The preparation was carried out according to the same steps as in Example 1, except that the raw material composition of the ultrathin glass was provided according to the formulations shown in Tables 2 to 7, and the process parameters shown in Tables 2 to 7 were used in the preparation process to obtain the corresponding comparative samples.

[0115] The glass samples of Examples 1 to 9 and the comparative samples of Comparative Examples 1 to 17 were subjected to performance tests, and the results are shown in Tables 1 to 7.

[0116] As can be seen from Tables 1 to 7, the polished and strengthened ultrathin glass prepared based on the embodiments of this application exhibits high surface compressive stress, high average pen drop height, and superior bending performance. It is evident that the ultrathin glass provided in this application, through the preparation of strengthened and polished ultrathin glass, is based on a specific range of glass components and the synergistic effect between these components. This allows the CS and BR coefficients of the ultrathin glass to meet the requirements and be compatible with each other, achieving a synergistic improvement in compressive strength, impact strength, and bending performance. In Comparative Examples 1 to 3, although the ranges of each component are within the required range, because they do not meet the formula requirements for achieving the specific synergistic effect, the resulting polished and strengthened ultrathin glass also struggles to achieve the desired CS and BR coefficients and compatibility as required by this application. This results in a deficiency where compressive strength, impact strength, and bending performance are difficult to simultaneously achieve, or even where none of the three requirements are met. Furthermore, in Comparative Examples 13 to 15, when each component in the glass only meets one of the required formula requirements, the deficiency of difficulty in simultaneously achieving compressive strength, impact strength, and bending performance is also observed. Therefore, it is evident that the composition range and specific synergistic adjustment of the glass components provided are essential for achieving its technical effect, and neither can be omitted. For example, the polished and strengthened ultrathin glass obtained in Comparative Example 1 has a CS of only 591 / 710 MPa, a dynamic bending resistance of 0.05 mm (NG), and a pen drop height of only 7.5 / 8.8 cm; the polished CS of Comparative Example 3 is only 621 / 735 MPa, with a pen drop height of only 8.4 / 9.2 cm; the polished CS of Comparative Example 14 is only 725 / 742 MPa, with a pen drop height of only 8.1 / 9.4 cm; and the polished CS of Comparative Example 15 is only 681 / 732 MPa, with a pen drop height of only 7.1 / 8.5 cm. It is clear that the composition range and the relationships between the components simultaneously satisfying Equations 1 and 2 are necessary to obtain the polished and strengthened ultrathin glass claimed in this application, providing the necessary substrate support.

[0117] Tables 1-7 also show that, after forming and before strengthening, controlling the total thickness deviation (surface TTV), roughness, and cutting marks (tooth depth, tooth aspect ratio) left by the cutting tool on the surface of the ultrathin glass substrate used in the polished and strengthened ultrathin glass provided in this application has a significant impact on the performance of the polished and strengthened ultrathin glass, especially its bending performance. This may be because, during the cutting process, the surface and edge microstructure of the substrate glass is not controlled within a certain range, resulting in new defects, inducing stress concentration, and causing a sharp drop in bending yield and dynamic bending failure. For example, in Comparative Example 4, the total thickness deviation (surface TTV) of the ultrathin glass substrate after cutting was not controlled below 5 μm, significantly affecting the bending performance of the resulting polished and strengthened ultrathin glass, leading to a failure in dynamic bending. In Comparative Examples 7 and 8, the surface roughness of the ultrathin glass substrate after cutting was too high, also significantly affecting the bending performance of the resulting polished and strengthened ultrathin glass, resulting in a failure in dynamic bending. Similarly, in Comparative Examples 9, 10, and 17, the excessively high aspect ratio of the serrated cut surfaces significantly affected the bending performance of the polished and strengthened ultrathin glass, resulting in NG (Not Acceptable) dynamic bending.

[0118] Furthermore, in this application, to obtain polished and strengthened ultrathin glass that combines compressive strength, impact strength, and bending performance, the compressive stress layer formed during the strengthening process needs to have balanced stress layer parameters designed to match the compressive stress layer depth and BR coefficient, avoiding a steep transition between the compressive stress layer and the tensile stress layer, which would lead to a sudden drop in fatigue resistance. As seen in Comparative Examples 11 and 12, the polished and strengthened ultrathin glass also exhibited a significant decrease in bending performance, with dynamic bending failing. During the polishing process, the C of the post-polished compressive stress layer also needs to be controlled. SIPSD This ensures that the compressive stress layer remains uniform after polishing, preventing damage to the stress layer. SIPSD The temperature rises significantly after polishing, leading to dynamic bending failure. For example, in Comparative Examples 5, 6, and 16, the uniformity of the compressive stress layer in the strengthened ultrathin glass was disrupted during polishing, significantly affecting its bending performance and resulting in no-go dynamic bending. Simultaneously, temperature fluctuations in the salt bath during the strengthening process also affect the uniformity of the compressive stress layer. As shown in Comparative Example 17, when the temperature fluctuation in the salt bath area is >2℃, the ion exchange rate becomes uneven, easily leading to an in-plane stress difference C in the strengthened ultrathin glass. SIPSD A surge in stress and a dispersed stress distribution can also significantly affect the bending stability of polished and reinforced ultrathin glass.

[0119] Therefore, the ultrathin glass provided in this application adopts a specific component range and the interrelationship between specific components satisfies the synergistic relationship of Equations 1-2, providing a substrate support for obtaining polished and strengthened ultrathin glass with both compressive strength, impact strength and bending performance; while in the preparation process, controlling the cutting defects and the uniformity of the compressive stress layer can provide intermediate material support for obtaining polished and strengthened ultrathin glass with both compressive strength, impact strength and bending performance, so that the polished and strengthened ultrathin glass obtained can also achieve good performance with both bending performance, strength performance and optical performance at the corresponding ultrathin thickness.

[0120] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this invention should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0121] Table 1

[0122] Table 2

[0123] Table 3

[0124] Table 4

[0125] Table 5

[0126] Table 6

[0127] Table 7

Claims

1. An ultrathin glass, characterized in that, The product comprises the following components by mass percentage of oxides: SiO2: 56.0 wt%~64.0 wt%; Al2O3: 16.5 wt%~21.5 wt%; ZrO2: 0.5 wt%~3.0 wt%; Na2O: 15 wt%~20.0 wt%; K2O: 0.0 wt%~3.0 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.30<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.

60.

2. The ultrathin glass according to claim 1, characterized in that, The thickness of the ultrathin glass is 0.02-0.40 mm, preferably 0.03-0.30 mm.

3. The ultrathin glass according to any one of claims 1 to 2, characterized in that, The arithmetic mean roughness (Ra) of the surface of the ultrathin glass is <0.5 nm, preferably <0.4 nm; and / or The total thickness deviation of the ultrathin glass is ≤4.0μm, preferably ≤2.0μm.

4. The ultrathin glass according to claim 3, characterized in that, The ultrathin glass, with a thickness of 0.02~0.40mm, has an optical transmittance of ≥91.0% at 550nm and a haze of <0.2%.

5. The ultrathin glass according to any one of claims 1 to 4, characterized in that, The serration depth h of the edge of the ultrathin glass is ≤10.0μm, and the ratio h / d of the depth h to the width d of the serration of the edge of the ultrathin glass is <1.

4.

6. The method for preparing ultrathin glass according to any one of claims 1 to 5, characterized in that: The raw materials for glass preparation are mixed, melted, and then subjected to a one-step molding process followed by annealing to obtain ultrathin glass.

7. The method for preparing ultrathin glass according to claim 6, characterized in that, The one-time forming process is selected from any one of narrow slit drawing, overflow drawing, secondary thinning method and float process.

8. The method for preparing ultrathin glass according to claim 6, characterized in that, The ultrathin glass also includes a cutting process and edge etching treatment, wherein the cutting process is selected from wheel cutting or laser cutting.

9. A reinforced ultrathin glass, characterized in that, The reinforced ultrathin glass includes a tensile stress layer and compressive stress layers located on both sides of the tensile stress layer, wherein the thickness of each compressive stress layer does not exceed 0.3 times the thickness t of the reinforced ultrathin glass. The central region of the tensile stress layer comprises the following components, based on the mass percentage of oxides: SiO2: 56.0 wt%~64.0 wt% Al2O3: 16.5 wt%~21.5 wt% ZrO2: 0.5 wt%~3.0 wt%; Na2O: 15.0 wt%~20.0 wt%; K2O: 0.0 wt%~3.0 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.3<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.

6.

10. The reinforced ultrathin glass according to claim 9, characterized in that, The thickness t of the reinforced ultrathin glass is 0.02~0.40 mm; and / or The surface roughness (Ra) of the reinforced ultrathin glass is <0.5 nm, preferably <0.4 nm; and / or The serrated depth h of the edge of the reinforced ultrathin glass is ≤10.0μm, and the ratio h / d of the depth h to the width d is <1.

4.

11. The reinforced ultrathin glass according to claim 9 or 10, characterized in that, The depth DOL of each compressive stress layer of the reinforced ultrathin glass is 0.1t < DOL < 0.3t.

12. The reinforced ultrathin glass according to any one of claims 9 to 11, characterized in that, The surface compressive stress CS of the reinforced ultrathin glass is ≥900MPa.

13. The reinforced ultrathin glass according to any one of claims 9 to 12, characterized in that, The reinforced ultrathin glass is obtained by strengthening the ultrathin glass prepared by the method of any one of claims 1 to 5 or any one of claims 6 to 8.

14. The reinforced ultrathin glass according to claim 13, characterized in that, The strengthening is a single-step chemical strengthening.

15. The reinforced ultrathin glass according to claim 14, characterized in that, The salt used in the enhanced salt bath includes 0-0.30 wt% lithium salt, 0-5 wt% sodium salt, and 95-100 wt% potassium salt; and / or The strengthening temperature is 350~500℃; and / or The strengthening time is 5~240 min.

16. A polished and strengthened ultrathin glass, characterized in that, The polished and strengthened ultrathin glass includes a tensile stress layer and compressive stress layers located on both sides of the tensile stress layer. The thickness of each compressive stress layer is less than 0.3 times the thickness t of the polished and strengthened ultrathin glass and more than 0.1 times the thickness t of the polished and strengthened ultrathin glass. The central region of the tensile stress layer comprises the following components, based on the mass percentage of oxides: SiO2: 56.0 wt%~64.0 wt% Al2O3: 16.5 wt%~21.5 wt% ZrO2: 0.5 wt%~3.0 wt%; Na2O: 15.0 wt%~20 wt% K2O: 0.0 wt%~3.0 wt%; MgO: 0.5 wt%~2.9 wt%; Each component simultaneously satisfies the following relationships (1) to (2): (1) 0.31<(0.7Al2O3+1.2MgO+0.25Na2O+0.6ZrO2-0.7K2O) / SiO2<0.37; (2) 1.3<(Al2O3+1.5MgO+2.5ZrO2) / (Na2O+0.8K2O)<1.

6.

17. The polished and strengthened ultrathin glass according to claim 16, characterized in that, When the thickness of the polished and strengthened ultrathin glass is 0.02~0.40mm, its optical transmittance at a wavelength of 550nm is ≥ 91.5%.

18. The polished and strengthened ultrathin glass according to claim 16 or 17, characterized in that, The surface compressive stress CS of the polished and strengthened ultrathin glass is ≥750MPa.

19. The polished and strengthened ultrathin glass according to any one of claims 16 to 18, characterized in that, The surface compressive stress CS, surface compressive stress layer depth DOL, and bending coefficient BR of the polished and strengthened ultrathin glass satisfy the following relationships (3) to (4): (3) BR= (CS*DOL*(1000t-DOL)) / 1000t (4) 100*1000t + 500 < BR < 125*1000t + 1750; Among them, the unit of surface compressive stress CS is MPa, the unit of compressive stress layer depth DOL is μm, and the unit of glass thickness t is μm; and / or The surface roughness (Ra) of the polished and strengthened ultrathin glass is <0.5 nm, preferably <0.4 nm; and / or The serration depth h of the edge of the polished and strengthened ultrathin glass is ≤10μm, and the ratio of the depth h to the width d is h / d <1.

4.

20. The polished and strengthened ultrathin glass according to any one of claims 16 to 19, characterized in that, The in-plane stress difference C of the polished and strengthened ultrathin glass SIPSD <50MPa.

21. The polished and strengthened ultrathin glass according to any one of claims 16 to 20, characterized in that, When the thickness of the polished and reinforced ultrathin glass is 0.03~0.05mm, the average pen drop height is >9.5cm.

22. The polished and strengthened ultrathin glass according to any one of claims 16 to 21, characterized in that, When the thickness of the polished and strengthened ultrathin glass is 0.03~0.05mm, the ultimate bending radius R1 < 1.0mm, the ultimate slip bending radius R2 < 1.5mm, and the ultimate dynamic bending radius R3 < 1.5mm.

23. The polished and strengthened ultrathin glass according to any one of claims 16 to 22, characterized in that, When the thickness of the polished and strengthened ultrathin glass is 0.03 mm, the yield rate of misalignment bending is >90% when the misalignment bending radius is 0.7 mm; and / or When the thickness of the polished and strengthened ultrathin glass is 0.05mm, the yield rate of misalignment bending is >90% when the misalignment bending radius is 1.1mm.

24. The polished and strengthened ultrathin glass according to any one of claims 17 to 23, characterized in that, The polished and strengthened ultrathin glass is obtained by strengthening and polishing the ultrathin glass according to any one of claims 1 to 5, or by strengthening and polishing the ultrathin glass prepared by the method of preparing ultrathin glass according to any one of claims 6 to 8, or by polishing the strengthened ultrathin glass according to any one of claims 9 to 15.

25. The polished and strengthened ultrathin glass according to claim 24, characterized in that, The strengthening is a single-step chemical strengthening, and the temperature fluctuation of the salt bath used for the strengthening is ≤2℃; and / or The polishing is chemical polishing, the polishing depth t1 is 1μm < t1 < 2.5μm, and the polishing rate v1 is 0.2μm / min < v1 < 1μm / min.

26. The application of the ultrathin glass as described in any one of claims 1 to 5, or the ultrathin glass prepared by the method described in any one of claims 6 to 8, or the reinforced ultrathin glass as described in any one of claims 9 to 15, or the polished reinforced ultrathin glass as described in any one of claims 16 to 25, in the field of electronic products.

27. A flexible folding device, characterized in that, The ultrathin glass includes any one of claims 1 to 5, or ultrathin glass prepared by any one of claims 6 to 8, or reinforced ultrathin glass according to any one of claims 9 to 15, or polished reinforced ultrathin glass according to any one of claims 16 to 25.

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