Safety-reinforced glass having a tensile stress region with a small variation width and a method for manufacturing the same

Abstract

To provide safety strengthened glass with a low-variation-amplitude tensile stress region.SOLUTION: In chemically strengthened glass, the change curve of the compressive stress and tensile stress meets a specific function relationship. Within the range of 0.45-0.85 mm, the stress distribution is such that: the stress curve is within the Log-PI function range where the upper limit Fmax of the compressive stress meets the formula (1) defined by Fmax=b+(2×a / PI)×(w / (4×(x-c)^2+w^2)) and where the lower limit Fmin of the compressive stress meets the formula (2) defined by Fmin=b+(2×a / PI)×(w / (4×(x-c)^2+w^2)); or the chemically strengthened glass comprises a first stress region and a second stress region, where the stress range of a first subregion in the first stress region has the minimum value of the stress difference value in a region where the glass thickness t is 0-10 μm is greater than 1 Mpa; and the pressure difference value of the second stress region is smaller than that of the first stress region.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to safety-reinforced glass having a tensile stress region with a small variation width, wherein the change rate in the tensile stress region of the glass substrate is gentle and stepwise, and the increase width is not large. Therefore, the tensile stress region has safety, and the glass is stable during use. It is suitable for electronic display devices, especially for regions to be covered and protected by electronic display devices.

Background Art

[0002] Chemical strengthened glass is formed by a high-temperature ion exchange process, in which large alkali metal ions in a high-temperature molten salt replace small alkali metal ions in the glass, resulting in a volume difference and gradually reducing tensile stress generated on the surface layer of the glass, suppressing and delaying the expansion of microcracks in the glass, thereby improving the mechanical strength of the glass.

[0003] The tensile stress region of chemical strengthened glass affects the stability of the glass. When the glass is subjected to impact, there is a risk that the glass will break due to the internal tensile stress. If the variation width is large, the glass will break even under a small impact, and the stability of the glass strength will be impaired. As a result, the performance of glass products is unstable, the usability is impaired, and mass production is also difficult.

[0004] There is still no suitable method for the strengthening standard and safety judgment of chemical strengthened glass in this section. Sometimes, since the two are in a contradictory relationship, if the strengthening of the glass is unidirectionally required, there is a high possibility that the glass will become unsafe beyond the tolerance limit. Moreover, it deviates from the optimal stress state in which the characteristics of the glass can be exerted. If the degree of strengthening is insufficient, the maximum strengthening of the glass is not achieved, and there is room for improvement in the glass strength.

[0005] When the structural strength of the chemically strengthened glass itself is insufficient and the tensile stress is too large, even a slight impact can cause it to crack like an explosion and even self-explode. This greatly impairs the reliability and safety of the product. Since the chemically strengthened glass requires a certain degree of compressive stress to maintain high mechanical strength with the accompanying tensile stress and compressive stress, internal tensile stress is involved. However, the internal stress can be optimized according to its distribution.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Conventional chemically strengthened glass cannot achieve both high mechanical strength and appropriate tensile stress, has insufficient strength stability, insufficient degree of strengthening, and problems such as being prone to cracking with explosion.

[0007] The present invention is made to solve the above technical problems, and an object thereof is to provide a safety-strengthened glass having a tensile stress region with a small variation width. Since the stress is high in the deep compressive stress region of the glass, the performance of preventing drop breakage can be effectively enhanced. Moreover, since the variation width in the tensile stress region is very small, it is excellent in stability and safety. The glass has higher mechanical strength and can particularly exhibit the performance of preventing drop breakage.

Means for Solving the Problems

[0008] Specifically, the present invention provides the following technical solutions. In one aspect of the present invention, within the range of 0.45 - 0.85 mm, the stress distribution is such that the stress curve is such that the upper limit Fmax of the compressive stress satisfies the formula (1): Fmax = b + (2×a / PI)×(w / (4×(x - c)^2 + w^2)), wherein Fmax represents the maximum value of the compressive stress of the glass, the value of b is -81, the value of a is 1.11×10 7 , w is 1.985, the value of c is -60.64, x is the depth of the stress point in μm, PI is the return value of the constant 3.14159265358979, The lower limit Fmin of the compressive stress satisfies Equation (2): Fmin = b + (2×a / PI)×(w / (4×(x - c)^2 + w^2)), wherein Fmin represents the minimum value of the compressive stress of the glass, the value of b is -120.94, the value of a is 1.11×10 7 , w is 1.3, the value of c is -72.64, x is the depth of the stress point, the unit is μm, The depth of the stress point is the depth that penetrates from the surface of the glass to the center of the glass. A chemically strengthened glass that satisfies the above conditions and is within the Log-PI function range is provided.

[0009] In another aspect of the present invention, the stress distribution includes a first stress region and a second stress region. The first stress region is a compressive stress region, and the second stress region is a tensile stress region. In the first section of the first stress region, the stress range is the stress difference value in the region where the thickness t of the glass is 0 - 10 μm. The minimum value is greater than 1 MPa, preferably greater than 5 MPa, more preferably greater than 10 MPa, and the maximum value is less than 100 MPa. The stress difference value is the absolute value of the difference between the compressive stress at the first 0.5 μm and the compressive stress (CS) at the latter 0.5 μm. The second section of the first stress region is in the region from 0.03T to DOL-0-1 and from DOL-0-2 to 0.97T in the thickness of the glass. The stress difference value of the region is 0.4 - 5 MPa, preferably 0.5 - 3.5 MPa. The second stress region has a smaller pressure difference value than the first stress region. The second stress region includes a first section to and the first section is in the region from DOL-0-1 to 0.4T and from 0.6T to DOL-0-2. The stress difference value of the region is less than 1 MPa, preferably less than 0.8 MPa, more preferably less than 0.5 MPa. And the second stress region includes a second section, the range is from 0.4T to 0.6T, and the stress difference value is less than 0.2 MPa, preferably less than 0.1 MPa. A chemically strengthened glass that satisfies the above conditions and has a stress distribution with the above characteristics, wherein its CT-LD is greater than 35000 MPa, preferably between the banding threshold value and the branching threshold value, is provided.

[0010] Preferably, the raw materials for manufacturing the chemically strengthened glass are based on mol%, SiO2 55 - 75%, Al2O3 8 - 22%, B2O3 0 - 5%, P2O3 0 - 5%, MgO 1 - 8%, ZnO 0 - 2%, ZrO2 0 - 2%, TiO2 0 - 2%, Na2O 0 - 5%, Li2O 4 - 13%, K2O 0 - 5%, SnO2 0.1 - 2%, and contain oxides in the above ratios.

[0011] Preferably, the raw materials for manufacturing the chemically strengthened glass are based on mol%, SiO2 61 - 70%, Al2O3 10 - 19%, B2O3 0%, P2O3 0%, MgO 2 - 6%, ZnO 0 - 1%, ZrO2 0.5 - 1%, TiO2 0.5 - 1%, Na2O 2 - 5%, Li2O 5.5 - 12%, K2O 1 - 2.8%, SnO2 0.1 - 0.4%, and contain oxides in the above ratios.

[0012] Preferably, in the chemically strengthened glass, the total mol% content of SiO2 and Al2O3 is greater than 80 mol%, or, Na2O is 1.5 - 5% based on mol%, or, Li2O is 5.5 - 12% based on mol%, preferably 8 - 12%, or, Na2O + Li2O is 7 - 18% based on mol%, preferably 10.5 - 14%, or, MgO is 2 - 7.5% based on mol%, preferably 2.5 - 5%.

[0013] Preferably, the raw materials for manufacturing the chemically strengthened glass further contain tin oxide and / or sodium chloride as a clarifying agent, preferably the content of both does not exceed 1 mol%, more preferably 0.4 - 1 mol%.

[0014] Preferably, the Vickers hardness of the chemically strengthened glass is 600 - 630 kgf / mm under the condition of a load of 300 g and a pressure holding time of 10 s 2 is.

[0015] Preferably, the Young's modulus of the chemically strengthened glass is 80 GPa or more.

[0016] Preferably, the atomic packing density of the chemically strengthened glass is greater than 0.531.

[0017] Preferably, the dielectric constant of the chemically strengthened glass is 5.5 - 7.5.

[0018] Preferably, the branching threshold of the chemically strengthened glass is 60% or more of its CT-LDmax, or the streak threshold is 50% or more of its CT-LDmax.

[0019] Preferably, the expansion and contraction rate of the chemically strengthened glass reaches 80% or more of the total expansion and contraction rate.

[0020] Preferably, the tensile stress CT-LD per unit length of the chemically strengthened glass is 30000 - 60000 MPa / mm, preferably 35000 - 50000 MPa / mm.

[0021] Preferably, the CS-30 of the chemically strengthened glass satisfies the formula: CS-30 = a × exp(-T / b) + c, where CS-30 is the compressive stress at a depth of 30 μm from the surface of the strengthened glass, in the formula, a is -485, b is 0.5, c is 278 + (+40 / T 2 or -40T 2 ) and T is the thickness of the strengthened glass in mm.

[0022] In another aspect of the present invention, as a manufacturing method of any of the above chemically strengthened glasses, a manufacturing method of one-step strengthening or multi-step strengthening is provided.

[0023] In the manufacturing method of the chemically strengthened glass, in the case of the one-step strengthening, a NaNO3 and KNO3 salt bath is used, and the mass content of KNO3 in the mixture is 30 - 95 wt%, preferably 80 - 90 wt%.

[0024] Preferably, the temperature of the molten mixture is 390 - 460°C, preferably 400 - 450°C, and ion exchange for 5 - 10 h is preferred.

[0025] Preferably, in the method for manufacturing the chemically strengthened glass, the multi-stage strengthening includes two-stage strengthening. In the first stage, a NaNO3 salt bath of 75 - 100 wt% is used, the temperature in the first stage is preferably 425 - 430°C, and ion exchange for 3 - 7 h is preferred. In the second stage, a NaNO3 salt bath of 0 - 10 wt%, preferably 3 - 10 wt% is used, the temperature in the second stage is preferably 430 - 440°C, and ion exchange for 1 - 3 h is preferred.

[0026] In another aspect of the present invention, there is provided a chemically strengthened glass manufactured by any of the above manufacturing methods.

[0027] In another aspect of the present invention, there is provided the use of any of the above chemically strengthened glasses in the display screen of a mobile phone, the display screen of a tablet computer, a portable game console, and the display screen of a portable digital device.

Advantages of the Invention

[0028] The chemically strengthened glass of the present invention has a change curve of its compressive stress and tensile stress satisfying the specific functional relationship described above. Since the stress is high in the deep compressive stress region and the change range is very small in the tensile stress region, the glass has excellent mechanical strength while having high stability and safety.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0030] The present invention provides chemically strengthened glass having the following stress characteristics. While the chemically strengthened glass has excellent mechanical strength, it has high stability and safety.

[0031] The chemically strengthened glass is such that the stress curve distribution satisfies any one of the following two conditions, preferably both of the following two conditions: (1) The stress curve is within the following Log-PI function range, The upper limit Fmax of the compressive stress satisfies Equation (1): Fmax = b + (2 × a / PI) × (w / (4 × (x - c)^2 + w^2)), In the formula, Fmax represents the maximum value of the compressive stress of the glass, the value of b is -81, the value of a is 1.11×10 7 , w is 1.985, the value of c is -60.64, x is the depth of the stress point, and the unit is μm. PI is the return value of the constant 3.14159265358979.

[0032] The lower limit Fmin of the compressive stress satisfies Equation (2): Fmin = b + (2 × a / PI) × (w / (4 × (x - c)^2 + w^2)), In the formula, Fmin represents the minimum value of the compressive stress of the glass, the value of b is -120.94, the value of a is 1.11×10 7 , w is 1.3, the value of c is -72.64, x is the depth of the stress point, and the unit is μm.

[0033] The depth of the stress point is the depth that penetrates from the surface of the glass to the center of the glass.

[0034] Specifically, the stress curve that satisfies the above conditions is as shown in FIG. 1. The horizontal axis DOL represents the depth of the stress point of the glass product, and the depth of the stress point is generally smaller than DOC (the depth at which the compressive stress in the glass product changes to tensile stress). As can be seen from FIG. 1, until the compressive stress changes to tensile stress in the stress curve of the glass of the present invention, the reduction gradient is lower than that of the stress lower limit change curve and higher than that of the stress upper limit curve.

[0035] Or, (2) the chemically strengthened glass has a stress distribution having the following characteristics. It includes a first stress region and a second stress region. The first stress region is a compressive stress region, and the second stress region is a tensile stress region. In the first section of the first stress region, the stress range is the stress difference value in the region where the thickness t of the glass is 0 - 10 μm. The minimum value is greater than 1 MPa, preferably greater than 5 MPa, more preferably greater than 7 MPa, and even more preferably greater than 10 MPa. The maximum value is less than 100 MPa.

[0036] The stress difference value is the absolute value of the difference between the stress at the first 0.5 μm and the stress at the next 0.5 μm (the surface compressive stress of the chemically strengthened glass, abbreviated as CS).

[0037] The second section of the first stress region is in the region from 0.03T to DOL - 0 - 1 and from DOL - 0 - 2 to 0.97T in the thickness of the glass. The stress difference value in the region is 0.4 - 5 MPa, preferably 0.5 - 3.5 MPa. DOL - 0 is the depth when the stress is 0. Since the glass has two surfaces, there are two stress curves that are symmetric to each other. One of them (explaining half of the glass). DOL - 0 - 1 is the boundary point of the front stress distribution, and DOL - 0 - 2 is the boundary point of the back stress distribution.

[0038] The first section of the first stress region is mainly the stress generated by potassium-sodium exchange. The compressive stress (CS) can reach a high level, but the reduction is intense and the stress layer is shallow. Therefore, it is effective for surface scratch resistance but insufficient for impact resistance. Therefore, it is not required that the surface CS is very high, and it is preferable that the stress changes uniformly. The chemically strengthened glass of the present invention reduces the stress difference value to less than 100 MPa, so as to alleviate the problem that when the stress difference between the surface CS and the internal stress is too large in chemical strengthening, microcracks are likely to expand and the impact resistance and flexural performance of the glass decrease. The first section of the first stress region is limited as described above.

[0039] In the drop breakage prevention test, the breakage is mainly caused by the impact of sharp objects such as gravel. In this test, the depth of the impact is generally 30 - 40 μm. When cracks spread at the tip and reach the tensile stress region, the cracks are likely to extend and cause breakage. The magnitude and distribution of the stress in the deep stress region of the glass are important factors for withstanding the impact in the drop breakage prevention test. The setting of the stress CS-30 at 30 μm of the glass is particularly important. In the second section of the first stress region, it is preferable that the compressive stress in CS-30 is high and the change range of the stress difference value is small, which helps to suppress the spread of cracks at the tip and improve the drop breakage prevention performance of the glass.

[0040] Specifically, a preferred embodiment of the stress distribution of the chemically strengthened glass of the present invention is as shown in FIG. 2.

[0041] The second stress region is a tensile stress region. The fact that the range of this region is larger than that of the first stress region has the effect of promoting crack expansion. Therefore, from the initial stage to the increasing stage, it is preferable that the increasing width is smaller and the stress difference value is smaller. With its gentle increase, the network structure with the tensile stress region helps to suppress cracks. Moreover, the stress in the tensile stress region increases gently and does not change abruptly, so stress concentration does not occur, which is more helpful for improving impact resistance performance and stability. Therefore, the tensile stress region should meet the following conditions.

[0042] The stress difference value of the second stress region is smaller than that of the first stress region.

[0043] The second stress region includes a first section to and the first section ranges from DOL-0-1 to 0.4T and from 0.6T to DOL-0-2. The stress difference value in this region is less than 1 MPa, preferably less than 0.8 MPa, and more preferably less than 0.5 MPa. The second stress region includes a second section with a range of 0.4T - 0.6T, and the stress difference value is less than 0.2 MPa, preferably less than 0.1 MPa.

[0044] In the range of 0T - 0.5T or T - 0.5T, the stress difference value gradually decreases.

[0045] The tensile stress CT-LD per unit length of the chemically strengthened glass is 30000 - 60000 MPa / mm, preferably 35000 - 50000 MPa / mm. The maximum value CT-CV in the tensile stress region is less than 100 MPa, preferably less than 90 MPa. CT-CV is one measured value in the tensile stress region CT, generally the maximum value of CT, the tensile stress at the center of the glass, and its abbreviation is CT-CV.

[0046] The CS is greater than 500 MPa, and the depth DOL-Tail of the stress generated by potassium-sodium exchange measured by FSm-6000 (the depth of the stress generated by potassium-sodium exchange) is less than 6 μm.

[0047] Since potassium-sodium exchange mainly occurs in the second strengthening, if the potassium-sodium ion exchange is advanced, some sodium ions in the glass move during sodium-lithium exchange, weakening the deep stress generated in the first exchange and impairing the anti-drop breakage performance of the glass. Therefore, the depth DOL-Tail of the stress of the strengthened glass is less than 6 μm. The potassium-sodium exchange is not very advanced.

[0048] The CS-30 of the chemically strengthened glass satisfies the formula: CS-30 = a×exp(-T / b)+c, and CS-30 is the compressive stress at a depth of 30 μm from the surface of the strengthened glass. where a is -485, b is 0.5, c is 278 + (+40 / T 2 or -40T 2 ), and T is the thickness of the strengthened glass, with the unit being mm.

[0049] In order to obtain the chemically strengthened glass that satisfies the stress characteristics, the present inventor specified the following glass substrate components and their characteristics. The glass substrate components are as follows.

[0050] In order to obtain the above glass, the present inventor has intensively studied and provides the composition of the glass described in Table 1 (the components are based on mol%).

Table 1

[0051] In the composition of the glass described in Table 1, the network is mainly composed of SiO2 and Al2O3. If there are more network structures in the glass, the quantity of bridging oxygen increases. Especially when SiO2 is abundant, the dielectric constant of conventional lithium-aluminum-silicon glass can be effectively reduced. Moreover, the strength of the network structure in the glass can be enhanced. When the strength of the network structure is high, it helps to reduce the stress relaxation effect due to ion exchange. As a result, the reduction of the deep-layer stress among the composite compressive stresses due to high temperature and long time during ion exchange is alleviated. Thus, with less alkali metal ions and a low alkali metal component content in the glass, by performing a single two-component ion exchange at high temperature, it is guaranteed that a composite compressive stress with a certain depth and a high tensile stress per unit length can be obtained. Reducing the content of alkali metal ions free in the network structure helps to reduce the dielectric constant.

[0052] In the above chemically strengthened glass, the total amount of SiO2 and Al2O3 is greater than 80 mol%.

[0053] B2O3 forms the secondary network structure of the glass. Adding it can promote the high-temperature melting of the glass, making it easier to melt. Moreover, adding B2O3 can accelerate the ion exchange rate in the glass. However, boron may weaken the network structure. Therefore, the addition amount of B2O3 is set to 0 - 5%.

[0054] Na2O is a main component involved in ion exchange and an important exchange ion for generating high compressive stress on the surface. However, it also has the effect of lowering the branching threshold and banding mark threshold of the glass, which is not favorable for improving the CT-Ldmax of the glass. Therefore, the content of Na2O is preferably 0 - 5% in mol%, more preferably 1.5 - 5%, and even more preferably 3 - 5%.

[0055] Li2O is a main component involved in ion exchange and an important exchange ion for generating deep compressive stress. The content of Li2O is preferably 5.5 - 12%, more preferably 8 - 12%.

[0056] Since Na2O and Li2O are alkali metal oxides and are in a free state inside the glass, when the cross-linking oxygen is cut off by excess oxygen ions and the network structure is broken, the dielectric constant of the glass increases. Moreover, the dielectric loss of the glass increases with the excessive number of alkali metal atoms. Therefore, Na2O + Li2O is set to 7 - 18%, preferably 10.5 - 14%.

[0057] K2O is a main component involved in ion exchange and can effectively adjust the dielectric constant of the glass. It is not preferable that the dielectric constant of the cover glass is excessively low due to the touch characteristics, nor is it desirable that the dielectric constant is excessively high in 5G communication. Therefore, it is considered to adjust the dielectric constant of the glass with K2O, and adding a small amount has no influence on potassium-sodium and sodium-lithium ion exchange. K2O is set to 0 - 5%.

[0058] MgO acts as a network intermediate to lower the high-temperature viscosity of the glass and increase the Young's modulus. On the other hand, since alkaline earth metals and alkali metals are the main carriers of current in the glass, if they are contained in large amounts, the dielectric constant and dielectric loss of the glass will increase significantly. Moreover, the introduction of different alkali metals and alkaline earth metals will mix the alkalis or alkaline earths, damaging the dielectric properties of the glass. Therefore, MgO is preferably 2 - 7.5%, more preferably 2.5 - 5%.

[0059] Since the melting temperature of the glass substrate is 1630 - 1700 °C, tin oxide and / or sodium chloride is used as a fining agent, and the content of both does not exceed 1 mol%.

[0060] The melting temperature of the glass with the above formulation is 1630 - 1700 °C, The Vickers hardness is 600 - 630 under the condition of a load of 300 g and a pressure holding time of 10 s.

[0061] A higher Vickers hardness is helpful for improving the scratch resistance of the glass, The Young's modulus of the chemically strengthened glass is 80 GPa or more.

[0062] The atomic packing density of the chemically strengthened glass is greater than 0.531, and the atomic packing density is calculated from the formulation and the density of the chemically strengthened glass.

[0063] The dielectric constant of the chemically strengthened glass is 5.5 - 7.5.

[0064] When using a cover glass, if the dielectric constant is too low, the touch performance will decrease, and if the dielectric constant is too high, it will affect the 5G communication signal.

[0065] In lithium-aluminum-silicon glass, sodium-lithium exchange is highly sensitive to lithium ions in the salt bath. Even a small amount of lithium ions can have a profound impact on the sodium-lithium exchange performance, resulting in a decrease in the deep compressive stress and CT-LDmax. As a result, the performance of preventing drop breakage weakens. Most of the lithium ions in the salt bath are those removed from the glass through sodium-lithium exchange.

[0066] Through repeated related tests, the extraction characteristics of lithium ions in the glass substrate of the present invention were determined as follows. The glass substrate is under the conditions of 100% sodium nitrate × 440 °C × 5 h (which means strengthening in a 100% sodium nitrate salt bath at a strengthening temperature of 440 °C for 5 h), with a 100 kg salt bath, and the lithium ions released into the salt bath through sodium-lithium exchange per square meter do not exceed 100 ppm of the total mass of the salt bath.

[0067] The branching threshold of the glass substrate (before strengthening) is 60% or more of its CT-LDmax, and the banded mark threshold is 50% or more of its CT-LDmax. When strengthened at 440 °C for 1 h in a salt bath of 5% sodium nitrate + 95% potassium nitrate, the CS measured by FSm-6000 is 450 MPa or more, and the DOL-tail is greater than 3 μm.

[0068] During the process of the glass breaking, the fracture region generated on the cross-section by the tensile stress appears like a banded mark. The banded mark threshold refers to the tensile stress per unit length of the glass when the glass is instantaneously fractured and a banded mark is generated on the cross-section of the glass. The branching threshold refers to the tensile stress per unit length of the glass when the glass is instantaneously fractured and branching occurs on the cross-section of the glass. The tensile stress per unit length (CT-LD) is the value of the ratio of the integral of the tensile stress in the cross-section in the thickness direction of the glass to the thickness.

[0069] To obtain chemically strengthened glass having the above characteristics, the following strengthening method is used.

[0070] The glass of the present invention is lithium-silicon-aluminum glass, K + -Na + 、Na+ -Li + A composite compressive stress layer is formed by binary ion exchange. + Since the radius of ions is small, they are easy to move and exchange in the network structure of the glass. Ion exchange strengthening may be carried out in multiple steps, for example, in two steps, or in one step.

[0071] In the case of the multi-stage method, in the first stage of tempering, the molar ratio of the sodium nitrate to the total amount of sodium nitrate and potassium nitrate in the salt bath is greater than the molar ratio of Na2O / Li2O+Na2O+K2O in the glass components, and the glass expansion / contraction ratio reaches 80% or more of the total expansion / contraction ratio, and in the final stage of tempering, the molar ratio of the sodium nitrate to the total amount of sodium nitrate and potassium nitrate in the salt bath is less than the molar ratio of Na2O / Li2O+Na2O+K2O in the glass components, and the glass expansion / contraction ratio is 1.5-2‰. The glass expansion / contraction ratio is the ratio of the amount of expansion to the size before expansion in chemically tempered glass, which expands in size after tempering.

[0072] Specifically, chemical ion exchange strengthening may be carried out in two stages as follows: (1) In the first stage, ion exchange is carried out in a mixed molten salt of NaNO3 and KNO3 with a NaNO3 content (wt%) of 30-100%, and Na + -Li + The main focus is on replacement (from glass to Li + (2) In the second stage, ion exchange is carried out in a mixed molten salt of NaNO3 and KNO3 with a NaNO3 content (wt%) of 0-10%, preferably 3-10wt%, and KNO3 is used. + -Na + The main exchange is (from glass to Na + After the two steps are completed, a thick layer of composite compressive stress is formed on the surface of the glass.

[0073] The chemical ion exchange strengthening of the glass according to the present invention may be carried out in one step as follows (hereinafter referred to as the one-step method or the single-time method). In the case of one step, the salt bath is a mixed salt bath of potassium nitrate and sodium nitrate, and the molar ratio of sodium nitrate to the total amount of sodium nitrate and potassium nitrate in the salt bath is smaller than the value of the molar ratio of Na2O / Li2O + Na2O + K2O in the glass composition and larger than the mol% of Na2O in all components. Generally, ion exchange is carried out in a mixed molten salt of NaNO3 and KNO3 with a KNO3 content (wt%) of 30-100%, and the strengthening temperature is 390-460°C. The expansion and contraction rate of the strengthened glass is 1.5-2‰.

[0074] In the strengthening of the above method, in the salt bath of each stage of strengthening, the molar ratio of lithium ions to all alkali metal ions in the salt bath is less than 0.25%. This is because lithium ions in the salt bath are ions that prevent potassium-sodium and sodium-lithium ion exchanges. Even a small amount of their presence will significantly weaken the ion exchange and impair the strengthening effect.

[0075] Before performing the chemical strengthening, it is necessary to perform a preheating process at 300-400°C for 10-30 minutes. Between each stage of multi-step strengthening, it is necessary to perform a heat transfer process at 350-500°C for 15-120 minutes.

[0076] In the above one-step strengthening or multi-step strengthening, when continuous strengthening is performed in batch units in the salt bath of each stage, when the surface CS of the batch is reduced to the first 10-20%, the strengthening of the glass is terminated. When continuous strengthening is performed in batch units in the salt bath of each stage, when the surface CS of the batch is reduced to the first 5-20%, the strengthening is terminated.

[0077] Hereinafter, the manufacturing method of the chemically strengthened glass of the present invention and the stress characteristics of the chemically strengthened glass of the present invention will be described in detail using examples.

[0078] Specific operation examples: [Example 1] At 1650 °C, each raw material (ordinary raw materials for industrial use) was combined in a platinum crucible in the component ratio of Formulation 1 and melted. After that, defoaming and clarification treatment was carried out using sodium chloride as a clarifying agent. Then, it was poured into a stainless-steel mold preheated to 300 °C (generally, preheating to 200 - 400 °C is acceptable), placed in a muffle furnace at 650 °C and annealed for 24 h. After that, it was cut and processed by a machine tool under CNC (computer numerical control), and polished to obtain a flat glass as smooth as a mirror. The size of the flat glass after the processing was 50×50×0.7 mm, which was used as a sample.

[0079] Subsequently, the Young's modulus of the sample was measured using sound waves, and the device was a high-temperature elastic modulus tester IET - 1600P.

[0080] Its dielectric constant was measured using a dielectric constant tester ITACA&AET.

[0081] The sample with a predetermined size processed as described above was placed in a high-sodium-containing salt for strengthening. Stress was measured by taking it out at regular intervals of time. The high-stress region on the surface and the deep-layer stress inside the strengthened sample were measured using a refractometer-type glass surface stress meter FSM - 6000LE and a scattered light photoelastic stress meter SLP - 1000 manufactured by Orihara Seisakusho, respectively. Its CT value changed like a parabola. That is, if it rises to the highest point quickly, if the strengthening continues, it will gradually decrease. The CT-LD also changes in this way, and the value corresponding to the highest point is CT-LDmax.

[0082] In the measurement using the stress meter SLP - 1000, the photoelastic coefficient and refractive index are set to perform the normal measurement of the surface compressive stress, the depth of the compressive stress, and the highest value CT-CV of the tensile stress region. The tensile stress per unit length is a calculated value, and the sum of the tensile stresses measured by the stress meter SLP - 1000 is divided by the thickness of the glass.

[0083] The surface compressive stress (MPa) is defined as follows. After chemical strengthening of the glass, when small-radius alkali metal ions on the surface are replaced by large-radius alkali metal ions and the large-radius alkali metal ions are packed in, compressive stress is generated on the surface of the glass, which is called the surface compressive stress. The depth of the compressive stress (μm) is the distance from the surface of the chemically strengthened glass to the position where the compressive stress is 0. The tensile stress CT-LD per unit length is the value of the ratio of the integral of the tensile stress in the cross-section in the thickness direction of the glass measured by the SLP stress meter to the thickness. As shown in Figure 3, the sample after strengthening has the stress distribution curve shown in the figure, and the integral of the tensile stress is the area of the tensile stress region.

[0084] The banded mark threshold is the CT-LD value of the glass when a banded mark is generated on the cross-section of the glass by instantaneous fracture.

[0085] The branching threshold is the CT-LD value of the glass when branching occurs on the cross-section of the glass by instantaneous fracture.

[0086] In the limit test of the glass, as the strengthening time increases, the internal stress increases. Specifically, it is the increase of CT-LD. When CT-LD reaches a predetermined value, it is fractured with an indenter based on Vickers hardness, and banded marks as shown in Figure 4 are generated on the cross-section. The CT-LD when the glass is fractured and just banded marks are generated on the cross-section is called the banded mark threshold.

[0087] After banded marks are generated on the sample, if strengthening is continued to increase the stress and it is fractured with an indenter based on Vickers hardness, cracks spread from the contact point and branch. The CT-LD when the glass is fractured and just crack branching occurs on the cross-section is called the branching threshold.

[0088] The process of the above-mentioned limit test is as follows. The glass sample is put into a pure sodium nitrate salt bath prepared at the time of use, strengthened at 430°C, and the glass is taken out every 30 minutes. When the temperature drops below 100°C, the sample is washed with water at room temperature, and the surface moisture is dried. Then, its CT-LD is measured with SLP1000 and the data is recorded. After the data measurement is completed, it is put into the salt bath again for 30 minutes of strengthening, taken out and measured. When it is confirmed that the data distribution is an inverted U-shaped parabola, fitting is performed, and the highest point of the parabola is CT-LDmax.

[0089] When CT-LD reaches a specific value (banded mark threshold), banded marks will occur on the cross-section. If strengthening continues and CT-LD increases to a specific value (branching threshold), branching will occur on the sample.

[0090] After completing the above-mentioned each performance measurement, for the glass sample with a thickness of 0.7 mm obtained as above, ion exchange is carried out with the molten salt of the mixture or single component described in Table 2, the temperature of each stage of ion exchange, and the ion exchange time to obtain strengthened glass.

[0091] Two-stage ion exchange is carried out on the said sample, specifically as follows.

[0092] For IOX1 (the first-stage ion exchange), it is set as 425°C × 100 wt% NaNO3 × 6 h (by exchanging in a 100 wt% NaNO3 molten salt at 425°C for 6 h, all similar descriptions in this specification have similar meanings. Thus, the temperature, composition, and ion exchange time of the molten salt used for ion exchange are described). For IOX2 (the second-stage ion exchange), it is 430°C × 97 wt% KNO3 + 3 wt% NaNO3 × 2 h (by exchanging in a mixed molten salt of 97 wt% KNO3 and 3 wt% NaNO3 at 430°C for 2 h).

[0093] Using the refractive index type glass surface stress meter FSM-6000LE and the scattered light photoelastic stress meter SLP-1000 manufactured by Orihara Manufacturing Co., Ltd., the high stress region on the surface and the deep layer stress inside the strengthened sample were measured respectively. Before and after strengthening, the change in size was measured using a two-dimensional image measuring instrument to calculate the magnification ratio.

[0094] After the strengthening was completed, the four-point bending test and the sandpaper impact drop test of the sample were carried out. Since the test results may be biased with only one sample, in this example, when performing the four-point bending test and the sandpaper impact drop test, 20 pieces were taken as one batch, and the strength was represented by the average value and stability. The details of the measurement method are as follows. The method for measuring the flexural strength is the four-point bending test. Specifically, for the strengthened glass sample, the flexural test was carried out as shown in Figure 5. The flexural strength is calculated by the formula: δ = 3F(L2 - L1) / 2bh 2 where F is the downward pressure, L1 is the distance between the upper points, L2 is the distance between the lower points, b is the width of the glass, and h is the thickness of the glass.

[0095] Figure 6 is a schematic diagram of the measurement method for the drop fracture prevention strength. As shown in Figure 6, specifically, the measurement method for the drop fracture prevention strength is to closely adhere a mold weighing 200 g and the strengthened glass sample with double-sided tape, and let the glass sample fall onto a marble slab covered with 120-mesh sandpaper on the surface, and the highest point where the glass sample does not crack is taken as the drop fracture prevention strength.

[0096] The measurement results of each performance parameter are as shown in Table 3.

[0097] [Example 2-6, Comparative Example 1] Operate under the same conditions as in Example 1, but there are differences in the composition of each glass used in the manufacture of the glass substrate described in Table 2, the strengthening conditions for ion exchange on the glass substrate described in Table 3, and the performance parameters of the final strengthened glass.

Table 2

[0098] From Table 2, it was found that the Young's modulus of the glass substrate obtained from the formulation of the present invention is greater than 83 GPa, the dielectric constant is less than 7, the CT-Ldmax is greater than 56000 MPa / mm, the branching threshold is greater than 43000 MPa / mm, and the banding threshold is greater than 38000 MPa / mm.

Table 3a

Table 3b

Table 3c

Table 3d

[0099] In Table 3, the stress difference value is the difference value of the stress calculated by measuring the depth of the stress point every 0.5 μm from the surface of the glass at 0 μm to the center of the thickness. That is, it is the absolute value of the difference between the compressive stress in the first 0.5 μm and the compressive stress (CS) in the latter 0.5 μm. Each stress difference value range in the above table is the range from the minimum stress difference value to the maximum stress difference value in each thickness interval to be measured.

[0100] In Table 3, Example 1-5 of the present invention was compared with Comparative Example 1 of the conventional product. Since the content of silicon and aluminum in the examples is higher than that in Comparative Example 1 and the alkali metal (Na2O + Li2O + K2O) is less than that in the comparative example, the product of the present invention has more network structures than the conventional product. Specifically, the sample of the example of the present invention has a higher Young's modulus than Comparative Example 1, and the increase in the Young's modulus indicates an improvement in the deformation prevention performance of the glass. And the reduction of the alkali metal is beneficial to the dielectric constant of the glass, and when used in a 5G mobile phone, the attenuation of the signal of the cover glass can be reduced.

[0101] Furthermore, regarding strength, the strength of glass is related to its inherent network structure and stress state. In the present invention, a dense network structure is obtained by increasing the ratio of silicon to aluminum, and while increasing the lithium content, the sodium content is significantly reduced by suppressing the sodium and lithium components. This is useful for sodium-lithium exchange, resulting in a higher compressive stress in the deep layer, and the CT-LD indicating the stress state, as a corresponding characteristic, far exceeds Comparative Example 1 of conventional products. Therefore, after final strengthening, Examples 1-5 of the present invention have a higher CT-LD than Comparative Example 1, and the drop fracture prevention strength, i.e., the impact resistance, far exceeds that of conventional products. Moreover, due to the high Young's modulus and low surface CS, the stress difference value is limited to 100 MPa, reducing the microcracks on the surface caused by stress changes. The flexural strength by four-point bending also exceeds Comparative Example 1, and the results are stable in one batch. In Comparative Example 1, although the stress difference value is excessively high, with a CS of 1000 MPa, there are many microcracks on the surface, the difference between batches is large, and the flexural strength is low due to the value fluctuating.

[0102] Regarding safety, the strengthening of the network structure increases the internal stress that the glass can withstand inside. Specifically, the branching threshold of the glass is higher than that of the comparative example. When the stress is high, it does not break and scatter when it cracks. Moreover, in the examples of the present invention, the CT-LD after strengthening is suppressed within the branching threshold in all cases, taking into account both strength and safety when cracking.

Table 4a

Table 4b

[0103] In Table 4, the stress difference value is the difference value of the stress calculated by measuring the depth of the stress point every 0.5 μm from the surface 0 μm of the glass to the center of the thickness. That is, it is the absolute value of the difference between the compressive stress in the first 0.5 μm and the compressive stress (CS) in the next 0.5 μm. Each stress difference value range in the above table is the range from the minimum stress difference value to the maximum stress difference value in each thickness interval to be measured.

[0104] As can be seen from Table 4, the stress curve distribution range plays a role in restricting the surface CS of the sample, the deep-layer stress CS-50, the CT value of the tensile stress, and the change range thereof to an optimal range. Thereby, the characteristics of the glass network structure of the present invention and its stress state are exerted, and the best drop damage prevention performance and safety can be obtained. In the said composition 3, standard strengthening was not performed, and the stress distribution was not within the range of the formula in Comparative Examples 2 and 3. In Comparative Example 2, since it is at the upper limit of the stress curve distribution, its deep-layer stress is insufficient, and CS-50 and CT-LD are lower than those in Example 3, so the decrease in the drop damage prevention strength was serious. In the case of Comparative Example 3, since it has reached the lower limit of the stress curve distribution, the deep-layer stress is sufficiently large and exceeds the branching threshold value, and the internal stress cannot be controlled in the glass network structure. Moreover, when the stress is very high, the internal defects become large. Therefore, although the drop damage prevention strength is high, there are variations in the results even in the same batch, and low values are likely to occur. When the glass sample breaks, it becomes small fragments less than 1 mm, and scatters around, so the safety is low.

Table 5a

Table 5b

[0105] In Table 5, the said stress difference value is the stress difference value calculated by measuring the depth of the stress point every 0.5 μm thickness from the surface 0 μm of the glass to the center of the thickness. That is, it is the absolute value of the difference between the compressive stress in the first 0.5 μm and the compressive stress (CS) in the next 0.5 μm. Each stress difference value range in the above table is the range from the minimum stress difference value to the maximum stress difference value in each thickness interval to be measured.

[0106] As can be seen from Table 5, the samples of different thicknesses of the glass of the present invention, after being strengthened, well matched the characteristics shown in the stress curve distribution schematic diagram of FIG. 1 up to 0.45 - 0.85 mm, and CT-LD was stable near the branching threshold value.

[0107] (Supplementary Note) (Supplementary Note 1) Within the range of 0.45 - 0.85 mm, the stress distribution is such that the stress curve is such that the upper limit of the compressive stress Fmax satisfies Equation (1): Fmax = b + (2×a / PI)×(w / (4×(x - c)^2 + w^2)), wherein, Fmax represents the maximum value of the compressive stress of the glass, the value of b is -81, the value of a is 1.11×10 7 , w is 1.985, the value of c is -60.64, x is the depth of the stress point, the unit is μm, PI is the return value of the constant 3.14159265358979, the lower limit of the compressive stress Fmin satisfies Equation (2): Fmin = b + (2×a / PI)×(w / (4×(x - c)^2 + w^2)), wherein, Fmin represents the minimum value of the compressive stress of the glass, the value of b is -120.94, the value of a is 1.11×10 7 , w is 1.3, the value of c is -72.64, x is the depth of the stress point, the unit is μm, The depth of the stress point is the depth that penetrates from the surface of the glass to the center of the glass. The chemically strengthened glass that satisfies the conditions within the Log - PI function range.

[0108] (Supplementary Note 2) The stress distribution includes a first stress region and a second stress region. The first stress region is a compressive stress region, and the second stress region is a tensile stress region. In the first section of the first stress region, the stress range is the stress difference value in the region where the thickness t of the glass is 0 - 10 μm. The minimum value is greater than 1 MPa, preferably greater than 5 MPa, more preferably greater than 10 MPa, and the maximum value is less than 100 MPa. The stress difference value is the absolute value of the difference between the compressive stress at the first 0.5 μm and the compressive stress (CS) at the latter 0.5 μm. The second section of the first stress region is the region from 0.03T to DOL - 0 - 1 and from DOL - 0 - 2 to 0.97T in the thickness of the glass. The stress difference value of the said region is 0.4 - 5 MPa, preferably 0.5 - 3.5 MPa. The second stress region has a smaller pressure difference value than the first stress region. The second stress region includes a first section, and the first section is the region from DOL-0-1 to 0.4T and from 0.6T to DOL-0-2. The stress difference value of the region is less than 1 MPa, preferably less than 0.8 MPa, more preferably less than 0.5 MPa. Moreover, the second stress region includes a second section, the range is 0.4T - 0.6T, and the stress difference value is less than 0.2 MPa, preferably less than 0.1 MPa. Chemically strengthened glass satisfying the condition, having a stress distribution characterized in that CT-LD is greater than 35000 MPa, preferably between the streak threshold value and the branching threshold value.

[0109] (Appendix 3) The production raw materials are based on mol%. The chemically strengthened glass according to Appendix 1 or 2, containing oxides in the ratio of SiO2 55 - 75%, Al2O3 8 - 22%, B2O3 0 - 5%, P2O3 0 - 5%, MgO 1 - 8%, ZnO 0 - 2%, ZrO2 0 - 2%, TiO2 0 - 2%, Na2O 0 - 5%, Li2O 4 - 13%, K2O 0 - 5%, SnO2 0.1 - 2%.

[0110] (Appendix 4) The production raw materials are based on mol%. The chemically strengthened glass according to Appendix 1 or 2, containing oxides in the ratio of SiO2 61 - 70%, Al2O3 10 - 19%, B2O3 0%, P2O3 0%, MgO 2 - 6%, ZnO 0 - 1%, ZrO2 0.5 - 1%, TiO2 0.5 - 1%, Na2O 2 - 5%, Li2O 5.5 - 12%, K2O 1 - 2.8%, SnO2 0.1 - 0.4%.

[0111] (Appendix 5) The total mol% content of SiO2 and Al2O3 is greater than 80 mol%. Or, Na2O is 1.5 - 5% based on mol%. Or, Li2O is 5.5 - 12% based on mol%, preferably 8 - 12%. Or, Na2O + Li2O is 7 - 18% based on mol%, preferably 10.5 - 14%. Or, the MgO is 2 - 7.5% on a mol% basis, preferably 2.5 - 5%, and is the chemically strengthened glass according to any one of Supplementary Notes 1 - 4.

[0112] (Supplementary Note 6) The production raw material further contains tin oxide and / or sodium chloride as a fining agent, preferably with the content of both not exceeding 1 mol%, more preferably 0.4 - 1 mol%, and is the chemically strengthened glass according to any one of Supplementary Notes 1 - 5.

[0113] (Supplementary Note 7) The Vickers hardness is 600 - 630 under the conditions of a load of 300 g and a pressure holding time of 10 s, and is the chemically strengthened glass according to any one of Supplementary Notes 1 - 6.

[0114] (Supplementary Note 8) The Young's modulus is 80 GPa or more, and is the chemically strengthened glass according to any one of Supplementary Notes 1 - 7.

[0115] (Supplementary Note 9) The atomic packing density is greater than 0.531, and is the chemically strengthened glass according to any one of Supplementary Notes 1 - 8.

[0116] (Supplementary Note 10) The dielectric constant is 5.5 - 7.5, and is the chemically strengthened glass according to any one of Supplementary Notes 1 - 9.

[0117] (Supplementary Note 11) The branching threshold is 60% or more of its CT - LDmax, or the banding threshold is 50% or more of its CT - LDmax, and is the chemically strengthened glass according to any one of Supplementary Notes 1 - 10.

[0118] (Supplementary Note 12) The glass expansion and contraction rate reaches 80% or more of the total glass expansion and contraction rate, and is the chemically strengthened glass according to any one of Supplementary Notes 1 - 11.

[0119] (Supplementary Note 13) The tensile stress CT-LD per unit length is 30,000 - 60,000 MPa / mm, preferably 35,000 - 50,000 MPa / mm, and the chemically strengthened glass described in any one of Supplementary Note 1-12.

[0120] (Supplementary Note 14) CS-30 satisfies the formula: CS-30 = a × exp(-T / b) + c, CS-30 is the compressive stress at a depth of 30 μm from the surface of the strengthened glass, wherein a is -485, b is 0.5, and c is 278 + (+40 / T 2 or -40T 2 ) and T is the thickness of the strengthened glass, with the unit being mm, and the chemically strengthened glass described in any one of Supplementary Note 1-13.

[0121] (Supplementary Note 15) The manufacturing method of the chemically strengthened glass described in any one of Supplementary Note 1-14, which is one-step strengthening or multi-step strengthening.

[0122] (Supplementary Note 16) In the case of the one-step strengthening, a NaNO3 and KNO3 salt bath is used, and the mass content of KNO3 in the mixture is 30 - 95 wt%, preferably 80 - 90 wt%, Preferably, the temperature of the molten mixture is 390 - 460 °C, preferably 400 - 450 °C, and ion exchange for 5 - 10 h is more preferable. The manufacturing method of the chemically strengthened glass described in Supplementary Note 15.

[0123] (Supplementary Note 17) The multi-step strengthening includes two-step strengthening. In the first step, a 75 - 100 wt% NaNO3 salt bath is used, the temperature in the first step is preferably 425 - 430 °C, and ion exchange for 3 - 7 h is preferable. In the second step, a 0 - 10 wt%, preferably 3 - 10 wt% NaNO3 salt bath is used, the temperature in the second step is preferably 430 - 440 °C, and ion exchange for 1 - 3 h is preferable. The manufacturing method of the chemically strengthened glass described in Supplementary Note 16.

[0124] (Supplementary Note 18) Chemically strengthened glass manufactured by the manufacturing method described in any one of Supplementary Notes 15-17.

[0125] (Supplementary Note 19) Use of the chemically strengthened glass described in any one of Supplementary Notes 1-14 or the strengthened glass described in Supplementary Note 18 in the display screen of a mobile phone, the display screen of a tablet computer, a portable game console, or the display screen of a portable digital device.

Claims

Claim 1: A chemically strengthened glass, within the range of the glass thickness of 0.45 - 0.85 mm, the stress distribution is such that the stress curve the upper limit Fmax of the compressive stress satisfies the formula (1): Fmax = b + (2 × a / PI) × (w / (4 × (x - c)^2 + w^2)), where Fmax represents the maximum value of the compressive stress of the glass, the value of b is -81, the value of a is 1.11×10 ７ , w is 1.985, the value of c is -60.64, x is the depth of the stress point in μm, and PI is the return value of the constant 3.14159265358979, the lower limit Fmin of the compressive stress satisfies the formula (2): Fmin = b + (2 × a / PI) × (w / (4 × (x - c)^2 + w^2)), where Fmin represents the minimum value of the compressive stress of the glass, the value of b is -120.94, the value of a is 1.11×10 ７ , w is 1.3, the value of c is -72.64, x is the depth of the stress point in μm, the depth of the stress point, which is the depth that penetrates from the surface of the glass to the center of the glass, is within the Log - PI function range, SiO ２ and Al ２ O ３ the total mol% content of is greater than 80 mol%, Na ２ O is 1.5 - 5% on a mol% basis, Li ２ O is 5.5 - 12% on a mol% basis, Na ２ O + Li ２ O is 7 - 18% on a mol% basis, the tensile stress CT - LD per unit length of the chemically strengthened glass is 30000 - 60000 MPa / mm, and the maximum value CT - CV in the tensile stress region is less than 100 MPa, A chemically strengthened glass that meets the conditions. Claim 2: the maximum value CT - CV in the tensile stress region is less than 90 MPa, The chemically strengthened glass according to Claim 1. Claim 3: The manufacturing raw materials are based on mol%, SiO ２ 55 - 75%, Al ２ O ３ 8 - 22%, B ２ O ３ 0 - 5%, P ２ O ３ 0 - 5%, MgO 1 - 8%, ZnO 0 - 2%, ZrO ２ 0 - 2%, TiO ２ 0 - 2%, Na ２ O 0 - 5%, Li ２ O 4 - 13%, K ２ O 0 - 5%, SnO ２ 0.1 - 2%, the chemically strengthened glass according to claim 1, containing oxides in the ratio.

4. The manufacturing raw materials are based on mol%, SiO ２ 61 - 70%, Al ２ O ３ 10 - 19%, B ２ O ３ 0%, P ２ O ３ 0%, MgO 2 - 6%, ZnO 0 - 1%, ZrO ２ 0.5 - 1%, TiO ２ 0.5 - 1%, Na ２ O 2 - 5%, Li ２ O 5.5 - 12%, K ２ O 1 - 2.8%, SnO ２ 0.1 - 0.4%, the chemically strengthened glass according to claim 1, containing oxides in the ratio.

5. MgO is 2 - 7.5% based on mol%, the chemically strengthened glass according to claim 1.

6. Li ２ O is 8 - 12% based on mol%, or, Na ２ O + Li ２ O is 10.5 - 14% based on mol%, or, MgO is 2.5 - 5% based on mol%, the chemically strengthened glass according to claim 1.

7. The chemically strengthened glass according to any one of claims 1-6, wherein the manufacturing raw material further contains tin oxide and / or sodium chloride as a clarifying agent.

8. The chemically strengthened glass according to claim 7, wherein the content of both tin oxide and / or sodium chloride as the clarifying agent is 0.4-1 mol%.

9. The chemically strengthened glass according to any one of claims 1-6, wherein the Vickers hardness is 600-630 under the conditions of a load of 300 g and a pressure holding time of 10 s.

10. The chemically strengthened glass according to any one of claims 1-6, wherein the Young's modulus is 80 GPa or more.

11. The chemically strengthened glass according to any one of claims 1-6, wherein the atomic packing density is greater than 0.

531.

12. The chemically strengthened glass according to any one of claims 1-6, wherein the dielectric constant is 5.5-7.

5.

13. The chemically strengthened glass according to any one of claims 1-6, wherein the branching threshold is 60% or more of CT-LDmax of the chemically strengthened glass, or the banded streak threshold is 50% or more of CT-LDmax of the chemically strengthened glass.

14. The chemically strengthened glass according to any one of claims 1-6, wherein the tensile stress CT-LD per unit length is greater than 35000 MPa / mm and does not exceed 60000 MPa / mm.

15. The chemically strengthened glass according to claim 14, wherein the tensile stress CT-LD per unit length is greater than 35000 MPa / mm and does not exceed 50000 MPa / mm.

16. It is one-step strengthening, using a salt bath of a mixture of NaNO ３ and KNO ３ The mass content of KNO ３ in the mixture is 30-95 wt%, The method for manufacturing chemically strengthened glass according to any one of claims 1 to 6, wherein the temperature of the mixture is 390 - 460°C.

17. The mass content of KNO ３ in the mixture is 80 - 90 wt%, The temperature of the mixture is 400 - 450°C, and ion exchange is performed for 5 - 10 h. The method for manufacturing chemically strengthened glass according to claim 16.

18. It is multi-stage strengthening. In the first-stage strengthening, the expansion and contraction rate of the glass reaches 80% or more of the total expansion and contraction rate, and the total expansion and contraction rate is the expansion and contraction rate after the final-stage strengthening is completed. The method for manufacturing chemically strengthened glass according to any one of claims 1 to 6.

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