Ion sieves, their preparation method and use

Abstract

The present application relates to the technical field of ion sieves, in particular to the technical field of removing impurities from salt baths for chemically strengthening glass, and specifically to an ion sieve having high temperature resistance and high temperature stability, its preparation method and use. The composition of the ion sieve is SiO 2 46-60 mol%, Al 2 O 3 3 to 16 mol%, Y 2 O 3 0 to 3 mol% and R 2 Contains 33 to 45 mol% of O, 2 O is an alkali metal oxide, and the ion sieve is [Formula 1] JPEG2025501821000031.jpg2965 is greater than or equal to 1. The ion sieve according to the present application has excellent high temperature resistance and high temperature stability, and even if it is placed in a high temperature salt bath for a relatively long time, it hardly undergoes significant crystal phase transition, has a stable structure, does not release a large amount of impurity substances that contaminate the salt bath, and does not cause significant defects on the surface of the finished glass product after tempering. The ion sieve according to the present application can continuously and stably adsorb impurity ions for 24 hours in a salt bath at 480°C.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority based on a Chinese application filed with the State Intellectual Property Office of the People's Republic of China on December 23, 2022, bearing application number 202211665025.4 and entitled "Ion sieve with high temperature resistance and high temperature stability, its preparation method and use," the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of ion sieves, in particular to the technical field of removing impurities from salt baths for chemically strengthening glass, and specifically to an ion sieve having high temperature resistance and stability, its preparation method and use. [Background technology]

[0003] In the chemical strengthening process of glass, alkali metal ions with small ionic radii (e.g., Na + , Li + ) is the alkali metal ion with a large ionic radius (e.g., K + , Na + ), causing a "clogging phenomenon" within a certain depth range, forming a specific stress distribution, preventing the extension of microcracks in the glass, and thus achieving the purpose of increasing the strength of the glass.Alkali metal ions with small ionic radii gradually enter the salt bath from the glass, resulting in an increase in the amount of alkali metal ions with small ionic radii in the salt bath, and the increased amount of alkali metal ions with small ionic radii becomes impurity ions in the salt bath.Alkali metal ions with small ionic radii (such as Li + If the amount of Li exceeds a certain level, the normal progress of chemical strengthening will be severely hindered, the stress level of the tempered glass will decrease, and the mechanical strength will be significantly reduced, so that the performance of the final product will not meet the requirements for use. +If the amount of is increased, the degree of lithium-sodium exchange when chemically strengthening lithium aluminosilicate glass will be significantly reduced, and the dimensional increase of the tempered glass will be rapidly reduced, making it impossible to meet the requirements for the dimensional deviation range of glass when applied to mobile phone covers, resulting in an increase in the dimensional defect rate of chemically strengthened glass.

[0004] In view of the above, the industry has proposed the introduction of impurity ion removal materials into the salt bath. Here, the impurity ion removal material is a material that can remove excess alkali metal ions with small ionic radius (e.g., Li + ) and remove the alkali metal ions with small ionic radii (e.g., Li + ) within a specified range, thereby ensuring the normal use of the salt bath and reducing the amount of alkali metal ions with a small ionic radius (e.g., Li + ) can be prevented from deteriorating the performance and quality of the glass due to an excessive amount of .

[0005] Phosphates and ion sieves are commonly used materials for removing impurity ions in glass factories. The principle of removing impurity ions using phosphates is to form precipitates by the reaction between phosphate ions and impurity ions. For example, if powdered sodium phosphate is added to a salt bath, lithium phosphate precipitates will be formed by the reaction between phosphate ions and lithium ions, and thus the impurity Li + However, lithium phosphate makes the salt bath cloudy, so it must be used after a long time for it to clear up. Furthermore, some lithium phosphate granules tend to adhere to the surface of tempered glass, causing defects in the glass. In other words, when phosphate is used as an impurity ion removal material, the effect of improving the salt bath is limited. To ensure the performance and quality of tempered glass, the salt bath must be frequently replaced within a short period of time, which is detrimental to improving mass production efficiency and increases tempering costs. Furthermore, if too much lithium phosphate precipitates at the bottom of the salt bath, the effective working area of ​​the salt bath is reduced, making the tempering bath difficult to clean.

[0006] To ensure mass production efficiency in glass factories, it is desirable to continuously add glass to be tempered to obtain chemically tempered glass that meets the requirements through tempering. It is also desirable to shorten the glass tempering time by increasing the temperature of the salt bath. To achieve this goal, a method is needed to effectively control the amount of impurity ions in the salt bath. If impurity ion removing materials are not usable for long periods of time and need to be replaced frequently, the tempering process is interrupted, reducing mass production efficiency. Furthermore, the amount of impurity ion removing material required increases. Furthermore, a large amount of molten salt is also removed during the removal of the impurity ion removing material. These two factors increase tempering costs. Therefore, an impurity ion removing material that can be used stably for long periods in high-temperature salt baths is needed to reduce the amount of molten salt used, improve production efficiency, and reduce production costs.

[0007] After discovering the drawbacks of using phosphate as a material for removing impurity ions, the present applicant developed an ion sieve material capable of adsorbing impurity ions in a salt bath. The applicant's prior patent application, CN112645610A, discloses a highly stable ion sieve free of boron and phosphorus and its use. This invention solves the problem of poor lithium ion adsorption capacity and poor adsorption rate in high-temperature salt baths during the production of chemically strengthened glass covers, particularly poor adsorption rate for poisoned lithium ions. The addition of the applicant's ion sieve effectively suppresses the content of impurity ions in the salt bath, avoiding the problems associated with using phosphate. However, further improvements in high-temperature resistance and stability are needed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Chinese Patent Application No. 112645610A Summary of the Invention [Problem to be solved by the invention]

[0009] The present application aims to provide an ion sieve with high temperature resistance and stability, which overcomes the drawbacks of prior art impurity ion removal materials that require further improvement in high temperature resistance and stability, as well as a preparation method and use thereof. This ion sieve has excellent high temperature resistance and can be stably used for a long time in a high-temperature salt bath. It also has excellent high-temperature stability, for example, being able to continuously adsorb impurity lithium ions for 24 hours in a 480°C salt bath, eliminating the need for frequent salt bath replacement. This ion sieve can improve the production efficiency and reduce the production costs of chemically strengthened glass, and has wide applications.

[0010] The present inventors conducted extensive research and discovered the reasons why it was difficult to further improve the high-temperature resistance and high-temperature stability of conventional impurity ion removal materials. Specifically, typical silicon-based ion sieves undergo significant crystalline phase transitions when used in high-temperature salt baths for extended periods. Such crystalline phase transitions impair the lithium ion adsorption performance of the ion sieve material and can even release lithium ions into the salt bath. Furthermore, crystalline phase transitions can release large amounts of impurities that contaminate the salt bath, impairing the quality of tempered glass and causing granules to adhere to the surface of the tempered glass. In light of this, the present inventors conducted further research and developed the present invention. The present invention solves the problem of silicon-based ion sieves being unable to stably adsorb lithium ions for extended periods of time due to the crystalline phase transitions that occur during chemical tempering, resulting in the release of large amounts of impurities and impairing the lifespan and high-temperature stability of the salt bath. [Means for solving the problem]

[0011] To achieve the above object, in a first aspect, the present application provides an ion sieve having high temperature resistance and stability. In the present application, the composition of the ion sieve includes, in terms of the mole percentage of each oxide in the ion sieve, 46 to 60 mole % of SiO, 3 to 16 mole % of AlO, 0 to 3 mole % of YO, and 33 to 45 mole % of RO, where RO is an alkali metal oxide, and the ion sieve is [ka] is greater than or equal to 1, [ka] However, the ion-sieving Raman spectrum shows a peak at 830-1230 cm -1 Q after Gaussian deconvolution fitting for the bands in the range 3 is the corresponding area of ​​Q 3 but Si-O in silicon-oxygen tetrahedrons with only one non-bridging oxygen - is a stretching vibration peak, [ka] However, the ion-sieving Raman spectrum shows a peak at 830-1230 cm -1 Q after Gaussian deconvolution fitting for the bands in the range 2 is the corresponding area of ​​Q 2 but Si-O in a silicon-oxygen tetrahedron with only two non-bridging oxygens - This is a stretching vibration peak.

[0012] In some alternative embodiments, the ion sieve has a crystalline content of less than 10 wt % after placing the ion sieve in a salt bath at 480° C. for 24 hours.

[0013] In some alternative embodiments, [ka] teeth [ka] Meet the following.

[0014] In some alternative embodiments, the composition of the ion sieve satisfies the following relationship: 52.0 > 0.85 x SiO2 + 0.15 x Al2O3 + 1.65 x Y2O3 > 45.3, in terms of mole percentage of each oxide in the ion sieve. Preferably, the composition of the ion sieve further satisfies 20.0≧0.50×R2O≧16.0 in terms of the mole percentage of each oxide in the ion sieve, where R2O is Na2O and / or K2O, and more preferably R2O is Na2O.

[0015] In some alternative embodiments, the ion sieve has a molar percentage of SiO2 of 49-60 mol%, and / or a molar percentage of Al2O3 of 3-15 mol%, and / or a molar percentage of Y2O3 of 1-3 mol%, and / or a molar percentage of R2O of 33-40 mol%.

[0016] In some alternative embodiments, the composition of the ion sieve further includes, in terms of the molar percentages of each oxide in the ion sieve, 0-3 mol% ZnO, 0-3 mol% CaO, 0-3 mol% MgO, 0-3 mol% P2O5, and 0-3 mol% B2O3, and the sum of the molar percentages of ZnO + CaO + MgO + P2O5 + B2O3 is 5 mol% or less.

[0017] Preferably, the ion sieve contains little P2O5 and / or B2O3. Preferably, the ion sieve contains little Li2O.

[0018] In some selectable embodiments, when the ion sieve with a mass percentage of 1 wt% based on the mass of the salt bath is put into a 480°C salt bath containing 105±10 ppm of impurity lithium ions, the change curve of the lithium ion concentration y in the salt bath over time x satisfies the function of y = A1×exp(-x / b1)+A2×exp(-x / b2)+C0, where exp is an exponential function, 100 > A1 > 30, 0 < A2 < 31, 0 < b1 < 5, 0 < b2 < 25, and 0 < C0 < 50, and the unit of x is time.

[0019] In some selectable embodiments, the ion sieve is granular, sheet-like or porous, preferably granular, and preferably the particle size of the granular ion sieve is 1 - 10 mm.

[0020] On the second aspect, this application provides a method for preparing an ion sieve according to the first aspect. This preparation method includes steps of weighing each raw material according to a formulation instruction and uniformly mixing them, then melting at a temperature of 1300 - 1650°C to obtain a liquid material, and preparing it as a granular, sheet-like or porous material.

[0021] In some selectable embodiments, granular ion sieves are formed by water quenching, and the temperature of water quenching is 10 - 80°C.

[0022] In some selectable embodiments, sheet-like ion sieves are formed by rolling or drawing with an external force.

[0023] In some selectable embodiments, porous ion sieves are formed by introducing a foaming agent.

[0024] On the third aspect, this application provides a method for removing impurities from a salt bath for chemical strengthening of glass. This impurity removal method includes a step of introducing the ion sieve according to the first aspect into an impurity-removing waiting salt bath at 350 - 550°C to perform an adsorption reaction of impurity ions.

[0025] In some alternative embodiments, the amount of the ion sieve used is 0.5 to 5.0% by weight of the salt bath for impurity removal.

[0026] In some alternative embodiments, the duration of the adsorption reaction is 0.1 to 48.0 hours.

[0027] In some alternative embodiments, the content of impurity ions in the impurity removal salt bath is 1 to 1000 ppm.

[0028] In a fourth aspect, the present application provides a method for preparing chemically strengthened glass, the method comprising the steps of introducing glass to be tempered and the ion sieve according to the first aspect into a salt bath for chemically strengthening glass that is free of impurity ions, and chemically strengthening the glass to be tempered to prepare the chemically strengthened glass.

[0029] This preparation method realizes online impurity removal using ion sieves, allowing the ion sieve impurity removal process to be carried out simultaneously with the glass tempering process, eliminating the need to temporarily suspend the tempering process or frequently change the salt bath, thereby improving the production efficiency of chemically tempered glass and reducing the production costs of chemically tempered glass.

[0030] (beneficial effects) After detailed research into ion sieves, it was found that ion sieves with specific compositions and structural requirements have excellent high-temperature resistance and stability, and even when placed in a high-temperature salt bath for a relatively long time, they rarely undergo significant crystalline phase transition, maintain a stable structure, do not release large amounts of impurities that contaminate the salt bath, and do not produce significant defects such as granules on the surface of the tempered glass.The ion sieve of the present invention can continuously and stably adsorb impurity ions in a 480°C salt bath for 24 hours, such as lithium ions that have a negative effect on glass tempering, ensuring that the surface quality of the tempered glass meets requirements. If the structure of the ion sieve does not meet the specific structural requirements of the present application, it will undergo significant crystalline phase transition after being left in a high-temperature salt bath for a relatively long time, which will significantly reduce the adsorption capacity and adsorption effect of the ion sieve on impurity ions. As a result, after being left in a high-temperature salt bath for a relatively long time, impurity ions and other impurity substances will be released from the ion sieve into the salt bath, contaminating the salt bath and causing significant defects such as granular defects on the surface of the finished glass product after tempering. [Brief explanation of the drawings]

[0031] In order to more clearly explain the technical concept of the embodiments of the present invention, the drawings used in the embodiments will be briefly described below. The drawings described are only for illustrating some embodiments of the present invention and are not intended to limit the scope. Those skilled in the art can obtain other related drawings based on these drawings without using inventive ability. [Figure 1a] 1 shows the initial XRD patterns of the ion sieves according to Examples 1 to 4. [Figure 1b] 1 shows initial XRD patterns of ion sieves according to Comparative Examples 1 to 4. [Figure 2a] 1 shows XRD patterns of ion sieves according to Examples 1 to 4 after absorbing lithium ions in a test salt bath at 480° C. for 24 hours. [Figure 2b]1 shows XRD patterns of ion sieves according to Comparative Examples 1 to 4 after adsorbing lithium ions in a test salt bath at 480° C. for 24 hours. [Figure 3a] 1 is a graph showing the tendency of change in lithium ion concentration over time when the ion sieves according to Examples 1 to 4 were used in a test salt bath at 480° C. [Figure 3b] 1 is a graph showing the tendency of change over time in the concentration of lithium ions when the ion sieves according to Comparative Examples 1 to 4 were used in a test salt bath at 480° C.; [Figure 4] 1 is a graph showing fitting results of the tendency of change in lithium ion concentration over time according to Example 1. [Figure 5] 10 is a graph showing fitting results of the tendency of change in lithium ion concentration over time according to Example 2. [Figure 6] 10 is a graph showing fitting results of the tendency of change in lithium ion concentration over time according to Example 3. [Figure 7] 10 is a graph showing fitting results of the tendency of change in lithium ion concentration over time according to Example 4. [Figure 8] 1 is a view showing the surface of a tempered glass product obtained by directly using the ion sieve according to Example 1 in a chemical tempering process. [Figure 9] 1 is a view showing the surface of a tempered glass product obtained by directly using the ion sieve according to Comparative Example 1 in a chemical tempering process. [Figure 10] 1 is a view showing the surface of a tempered glass product obtained by directly using the ion sieve according to Comparative Example 2 in a chemical tempering process. DETAILED DESCRIPTION OF THE INVENTION

[0032] The endpoints of the ranges and any values ​​disclosed herein are not limited to the specific ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. In the case of numerical ranges, combining the endpoints of each range with an individual specific value, and combining an individual specific value, can result in one or more new numerical ranges, and these numerical ranges should also be considered to be specifically disclosed herein. The terms "optionally" and "optionally" mean either inclusive or exclusive (may or may not be present).

[0033] The measurement method according to the present application is as follows. 1. Raman Spectroscopic Measurement of Ion Sieves The ion sieve is pulverized to a particle size of less than 75 μm and measured using a laser Raman spectrometer to obtain a Raman spectrum. Measurement conditions: Wavenumber range 100 to 1500 cm -1 and the spectral resolution is 1-2 cm -1 is. The laser Raman spectrometer used in this application is manufactured by Renishaw Ltd. in the UK and has the model number INVIA.

[0034] 2. XRD Pattern Measurement of Ion Sieves (1) XRD pattern measurement of the initial ion sieve The initial ion sieve not used for removing salt bath impurities is pulverized to a particle size of less than 75 μm and measured using an X-ray diffractometer to obtain an XRD diffraction peak profile, i.e., an XRD pattern. Measurement conditions: incident angle range 2θ = 10° to 80°, scan rate 6° / min, operating voltage 40 kV, operating current 30 mA. (2) XRD pattern measurement of ion sieves after use in salt bath impurity removal The initial ion sieve is placed in a test salt bath at 480°C containing 1000 ppm or less of lithium ion impurities, and removed after 24 hours of impurity removal. The removed ion sieve is pulverized to a particle size of less than 75 μm and measured using an X-ray diffractometer to obtain an XRD diffraction peak profile, i.e., an XRD pattern. The test salt bath used in this application is a sodium nitrate salt bath containing 105±10 ppm of lithium ion impurities. Measurement conditions: incident angle range 2θ = 10° to 80°, scan rate 6° / min, operating voltage 40 kV, operating current 30 mA. The X-ray diffraction apparatus used in this application is a Shimadzu XRD_6100.

[0035] 3. Measurement of the crystalline content in ion sieves The crystalline content of the ion sieve is expressed as the ratio of the crystalline peak area in the XRD pattern of the ion sieve after use in the salt bath impurity removal. That is, the ratio of the crystalline peak area fitted based on the XRD pattern to the total fitted peak area is the crystalline content. In this application, an X-ray diffractometer is used to measure the ion sieve after it has been used to remove impurities from the salt bath, and the measurement result file (RAW format) from the X-ray diffractometer is imported into X-ray diffraction data Rietveld refinement software (e.g., Jade, Gsas, Fullprof, Maud) for fitting and calculation. In this application, the measurement result file (RAW format) from the X-ray diffractometer is imported into Jade for fitting and calculation to obtain the crystal content in the ion sieve.

[0036] 4. Measuring the concentration (also called content) of lithium ions in a salt bath The ion sieve is placed in a salt bath for impurity removal, and the concentration of lithium ions in the salt bath at different times is measured using an atomic absorption spectrophotometer, with time being a variable.

[0037] In a first aspect, the present application provides an ion sieve having high temperature resistance and high temperature stability. The composition of the ion sieve, in terms of the mole percentage of each oxide in the ion sieve, includes 46-60 mole % of SiO, 3-16 mole % of AlO, 0-3 mole % of YO, and 33-45 mole % of RO, where RO is an alkali metal oxide. The ion sieve comprises: [ka] is greater than or equal to 1, [ka] However, the ion-sieving Raman spectrum shows a peak at 830-1230 cm -1 Q after Gaussian deconvolution fitting for the bands in the range 3 is the corresponding area of ​​Q 3 but Si-O in silicon-oxygen tetrahedrons with only one non-bridging oxygen - is a stretching vibration peak, [ka] However, the ion-sieving Raman spectrum shows a peak at 830-1230 cm -1 Q after Gaussian deconvolution fitting for the bands in the range 2 is the corresponding area of ​​Q 2 but Si-O in a silicon-oxygen tetrahedron with only two non-bridging oxygens - This is a stretching vibration peak. area [ka] and area [ka] The units are the same.

[0038] The principle of action of the oxides of each component is as follows: SiO2 forms covalent bonds and constitutes the framework of the ion sieve network structure. Selection of its structure and content directly affects the adsorption properties of the ion sieve network structure and the thermal stability of the ion sieve in high-temperature environments. If the SiO2 content is too low, the ion sieve will be poorly moldable. If the SiO2 content is too high, the composition will have a relatively high viscosity, making it difficult to melt. Therefore, in the present invention, the SiO2 molar percentage is 46 to 60 mol%. In some embodiments, the SiO2 content is 46 mol%, 47 mol%, 48 mol%, 49 mol%, 50 mol%, 51 mol%, 52 mol%, 53 mol%, 54 mol%, 55 mol%, 56 mol%, 57 mol%, 58 mol%, 59 mol%, 60 mol%, etc., as well as ranges and subranges defined by any of the above values. In embodiments, any of the above ranges can be combined with any other range.

[0039] Al2O3 is a component of the network structure and is advantageous in improving the adsorption rate of impurity ions during the adsorption process of the ion sieve and in improving the decomposition resistance of the ion sieve in high-temperature environments. However, too much aluminum oxide makes it difficult to form the ion sieve. Therefore, in the present invention, the molar percentage of Al2O3 is 3 to 16 mol%. In some embodiments, the Al2O3 content is 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol%, 16 mol%, etc., as well as ranges and subranges defined by any of the above values. In embodiments, any of the above ranges can be combined with any other range.

[0040] An appropriate amount of Y2O3 can improve the hardness and chemical stability of the ion sieve, but a relatively high Y2O3 content increases the tendency of the ion sieve to devitrify. Therefore, in the present invention, the molar percentage of Y2O3 is 0 to 3 mol%. In some embodiments, the Y2O3 content is 0, 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, etc., as well as ranges and subranges defined by any of the above values. In embodiments, any of the above ranges can be combined with any other range.

[0041] Alkali metal oxide R2O, on the one hand, provides alkali metal ions for ion exchange, contributing to the adsorption capacity of the ion sieve for impurity ions, and on the other hand, provides free oxygen, affecting the structural stability of the ion sieve. That is, the R2O content directly affects the ion sieve's ability to adsorb impurity ions and its stability in a high-temperature salt bath. Therefore, in the present invention, the R2O molar percentage is 33 to 45 mol%. In some embodiments, the R2O content is 33 mol%, 34 mol%, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, 45 mol%, etc., as well as ranges and subranges defined by any of the above values. In embodiments, any of the above ranges can be combined with any other range.

[0042] In some alternative embodiments, the ion sieve has a crystalline content of less than 10 wt % after being placed in a salt bath at 480° C. for 24 hours, where the crystalline content is expressed as a percentage of the crystalline peak area in the XRD pattern of the ion sieve.

[0043] In the present invention, the Gaussian deconvolution fitting is performed by importing a measurement result file (.txt format) from a laser Raman spectrometer into Origin (for example, Origin2022 version) and performing a Gaussian deconvolution fitting at 830 to 1230 cm -1By selecting a band within the range and performing deconvolution fitting and calculation using a Gaussian function, Q 3 and Q 2 The corresponding areas of each of the fitted Q 3 Area and fitted Q 2 The ratio to the area is [ka] is.

[0044] In some alternative embodiments, [ka] but [ka] Meet the following.

[0045] In some embodiments, [ka] The value of is 1.00, 1.05, 1.30, 1.50, 2.00, 2.30, 2.50, 2.80, 3.00, etc., as well as ranges and subranges defined by any of the above values. In embodiments, any of the above ranges can be combined with any other range. According to the inventor's research and verification, the ion sieve of the present invention, which has a specific composition and meets specific structural requirements, has excellent high-temperature resistance and high-temperature stability. Even when the ion sieve is placed in a high-temperature salt bath for a relatively long time, it hardly undergoes any significant crystalline phase transition and is structurally stable.

[0046] In some alternative embodiments, the composition of the ion sieve satisfies the following condition: 52.0 > 0.85 x SiO2 + 0.15 x Al2O3 + 1.65 x YO3 > 45.3, where the mole percentage of each oxide in the ion sieve is 52.0 > 0.85 x SiO2 + 0.15 x Al2O3 + 1.65 x YO3 > 45.3. When using this alternative embodiment, detailed studies by the inventors of the present application have shown that the degree of influence of each major component oxide on high temperature stability varies, and when the above condition is met, [ka] It is possible to obtain an ion sieve having a specific structure that satisfies the condition of 1 or more, which can significantly improve the structural stability of the ion sieve and is advantageous for melting and molding the ion sieve.

[0047] In some embodiments, the value of 0.85×SiO2 + 0.15×Al2O3 + 1.65×YO3 is 45.3, 46.0, 47.0, 48.0, 49.0, 50.0, 51.0, 51.5, 52.0, etc., as well as ranges and subranges defined by any of the above values. In embodiments, any of the above ranges can be combined with any other range.

[0048] In the above alternatives, Y2O3 may or may not be contained. When Y2O3 is contained, the effect of Y2O3 on the structural stability of the ion sieve is much greater than that of SiO2 and Al2O3, so controlling the Y2O3 content within the above conditions is more advantageous for improving high-temperature stability.

[0049] In the present invention, the ion sieve may further contain other components as long as the following condition is satisfied: 52.0 ≥ 0.85 × SiO2 + 0.15 × Al2O3 + 1.65 × Y2O3 ≥ 45.3.

[0050] In some alternative embodiments, the composition of the ion sieve satisfies 20.0 ≥ 0.50 × R2O ≥ 16.0 in terms of the molar percentage of each oxide in the ion sieve, where R2O is Na2O and / or K2O. Alkali metal oxides can provide alkali metal ions used for ion exchange, contributing to ensuring the adsorption capacity of the ion sieve for impurity ions, and can also provide free oxygen, affecting the structural stability of the ion sieve. In the present invention, when 0.50 × R2O is within the range of 16.0 to 20.0, the ion sieve has excellent adsorption capacity and ensures structural stability. When chemically strengthening general glass, exchange of Na ions and Li ions contained in the glass occurs primarily with K ions and Na ions in the salt bath. The impurity ions present in the salt bath are primarily Li ions released from the glass into the salt bath. If the R2O in the ion sieve is Na2O and / or K2O, it can better adsorb impurity ions in the salt bath and remove impurities from the salt bath.

[0051] Preferably, R2O is Na2O. When chemically strengthening glass, Na-Li exchange can create a deeper compressive stress layer, which is advantageous for improving the impact resistance of the glass. To achieve this, Li ions in the glass are replaced by Na ions in the salt bath, which then enter the salt bath and become impurity ions. Furthermore, according to the inventor's research, if the concentration of impurity lithium ions in the salt bath is too high, it is very detrimental to strengthening the glass. If all of the R2O in the ion sieve is Na2O, it can better adsorb impurity ions in the salt bath and remove impurities from the salt bath.

[0052] Preferably, the ion sieve has a molar percentage of SiO2 of 49 to 60 mol %. Preferably, in the ion sieve, the molar percentage of Al2O3 is 3 to 15 mol %. Preferably, the molar percentage of Y2O3 in the ion sieve is 1 to 3 mol %. Preferably, the molar percentage of R2O in the ion sieve is 33 to 40 mol %.

[0053] The ion sieve of the present invention may further contain other metal oxides. Preferably, the composition of the ion sieve further contains, in terms of mole percentages of each oxide in the ion sieve, 0-3 mol% of ZnO, 0-3 mol% of CaO, 0-3 mol% of MgO, 0-3 mol% of PO5, and 0-3 mol% of BO3. Preferably, the total molar percentage of ZnO + CaO + MgO + P2O5 + B2O3 is 5 mol% or less. This alternative embodiment is more advantageous for the high-temperature stability of the ion sieve, for reducing the amount of crystal precipitation, and for preventing a decrease in the adsorption efficiency of the ion sieve.

[0054] In the present invention, P2O5 and B2O3 may be included as components of the ion sieve. However, if the content of these components is too high, the chemical durability of the ion sieve will be impaired and random erosion of the surface of glass or microcrystalline glass will occur when used in a high-temperature salt bath. Therefore, the ion sieve of the present invention preferably contains almost no P2O5 and / or B2O3. Here, "almost no" means that at least one of P2O5 and B2O3 is not added to the ion sieve or introduced as a raw material, but may be present in very small amounts as a contaminant or impurity.

[0055] In the present invention, the ion sieve contains almost no Li2O. If the ion sieve contains Li2O, it is likely to impair the effect of the ion sieve in adsorbing impurity lithium ions.

[0056] In some selectable embodiments, when the ion sieve with a mass percentage of 1% by mass based on the mass of the salt bath is put into a 480°C salt bath containing 105±10 ppm of impurity lithium ions, the change curve of the lithium ion concentration y in the salt bath with respect to the passage of time x satisfies the function of y = A1×exp(-x / b1)+A2×exp(-x / b2)+C0, where exp is an exponential function, 100 > A1 > 30, 0 < A2 < 31, 0 < b1 < 5, 0 < b2 < 25, 0 < C0 < 50, and the unit of x is h (hour). According to this selectable embodiment, the ion sieve according to the present application can achieve continuous and stable adsorption of impurity lithium ions in a high-temperature salt bath for a long time. That is, the ion sieve according to the present application has excellent high-temperature stability and impurity ion adsorption ability.

[0057] In the above function, if a data relationship (mathematical model) is established based on the predetermined discrete data of y and x, a series of tiny straight line segments are obtained and these interpolation points are connected to form a curve, a smooth curve is formed. This curve is represented by exp (exponential function), and A1, A2, b1, b2, and C0 are all coefficients and are determined by the predetermined discrete data.

[0058] Those skilled in the art can select the shape and particle size of the ion sieve according to actual needs.

[0059] In some alternative embodiments, the ion sieve is granular, sheet-like, or porous, preferably granular. Preferably, the particle size of the granular ion sieve is 1 to 10 mm. In some embodiments, the particle size of the granular ion sieve is 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc., as well as ranges and subranges defined by any of the above values. Preferably, the particle size of the granular ion sieve is 2 to 5 mm. In some embodiments, any of the above ranges can be combined with any other range. Here, "particle size of the ion sieve" refers to the maximum diameter of the ion sieve granules.

[0060] In a second aspect, the present application provides a method for preparing the ion sieve according to the first aspect, which comprises the steps of weighing and uniformly mixing raw materials according to a formula (components of the ion sieve according to the first aspect), melting the mixture at a temperature of 1300 to 1650°C to obtain a liquid material, and then preparing the liquid material into a granular, sheet, or porous form.

[0061] In some alternative embodiments, the melting time is 1 hour or more, which can ensure that each raw material is completely melted and uniformly mixed.

[0062] In the present application, the granular ion sieve may be formed by water quenching. Preferably, the water quenching temperature is 10 to 80°C. In some embodiments, the water quenching temperature is 10°C, 15°C, 20°C, 22°C, 25°C, 30°C, 35°C, 45°C, 50°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc., as well as ranges and subranges defined by any of the above values. In embodiments, any of the above ranges can be combined with any other range. The size of the ion sieve granules can be controlled by controlling the temperature, thereby ensuring that the particle size of the ion sieve granules is within the range of 1 to 10 mm.

[0063] In some alternative embodiments, a sheet-shaped or porous ion sieve may be prepared according to the needs of use. For example, the sheet-shaped ion sieve may be formed by rolling or drawing with an external force. Preferably, the sheet-shaped ion sieve is an irregular sheet, with the shortest side of the sheet-shaped ion sieve being 0.3 cm or more, the longest side being less than 20 cm, and the thickness being 0.3 to 1.0 mm. For example, a porous ion sieve may be formed by introducing a foaming agent. Preferably, the pore size is 1 to 10 mm, and the porous ion sieve block preferably has the shortest side of 0.5 cm or more and the longest side being less than 10 cm.

[0064] The ion sieve of the present invention can be used to remove impurities from a salt bath containing impurity ions, or can be directly introduced into a chemical strengthening treatment, and can adsorb / absorb lithium ions in the salt bath during the chemical strengthening treatment, making it widely applicable.

[0065] In a third aspect, the present application provides a method for removing impurities from a salt bath for chemically strengthening glass. This method includes the step of introducing the ion sieve according to the first aspect into a salt bath for impurity removal to perform an adsorption reaction of impurity ions. The temperature of the salt bath for impurity removal is 350 to 550°C, which is advantageous in that the ion sieve's adsorption / absorption performance for lithium ions can be fully exhibited. The impurity ions adsorbed / absorbed by the ion sieve are mainly lithium ions.

[0066] The "impurity ions" here refer to ions that are not intentionally introduced into the salt bath when preparing the initial salt bath, such as lithium ions. The "adsorption reaction" here refers to the adsorption of alkali metal ions with a large ionic radius in the ion sieve, such as K. + YaNa + , is an impurity alkali metal ion with a small ionic radius in the salt bath, e.g., Li + , and the impurity alkali metal ions in the salt bath are adsorbed onto the ion sieve, thereby realizing the removal of impurities from the salt bath.

[0067] In the present invention, "impurity removal from a salt bath" may refer to online impurity removal, or impurity removal from a salt bath after glass strengthening or from a salt bath containing excess impurity ions. Online impurity removal refers to directly introducing an ion sieve into an initial salt bath containing no impurity ions. For example, an ion sieve is placed on a carrier (such as a metal mesh) and placed in the salt bath, and the impurity removal process (the process of adsorbing impurity ions in the salt bath) using the ion sieve is carried out simultaneously with the glass strengthening process. Impurity removal from a salt bath after glass strengthening or from a salt bath containing excess impurity ions refers to introducing an ion sieve into a salt bath containing impurity ions to adsorb the impurity ions during or after the strengthening process has been stopped.

[0068] In some alternative embodiments, the amount of the ion sieve used is 0.5 to 5.0 wt % of the salt bath for impurity removal. In the present application, a relatively small amount of the ion sieve can be used to effectively remove impurities from the salt bath, and the ion sieve according to the present application has excellent high-temperature resistance and high-temperature stability.

[0069] The salt bath for removing impurities according to the present application may be a potassium salt bath, a sodium salt bath, or a mixed salt bath of sodium and potassium (i.e., a mixed salt bath containing lithium (impurity ions), sodium, and potassium) containing a large amount of impurity lithium ions, and the above salt bath is preferably a nitrate bath.

[0070] The content of the lithium ions contained in the impurity-removing salt bath according to the present invention can be selected from a wide range, and the impurities can be removed using the ion sieve according to the present invention. For example, the content of the lithium ions contained in the impurity-removing salt bath is 1 to 1000 ppm.

[0071] In some alternative embodiments, the reaction time is 0.1 to 48.0 hours. The ion sieve according to the present application has excellent impurity ion adsorption capacity and can efficiently remove impurities from a salt bath containing impurity ions in a relatively short time. Furthermore, the ion sieve according to the present application has excellent high-temperature stability, can maintain a stable structure even in a high-temperature salt bath, and is unlikely to undergo significant crystalline phase transition. Therefore, this ion sieve can continuously and stably adsorb impurity ions for 24 hours in a salt bath at 480°C, better achieving online impurity removal, and does not require frequent replacement of the salt bath or ion sieve material, which is advantageous for improving the mass production efficiency and reducing costs of chemically strengthened glass.

[0072] In a fourth aspect, the present application provides a method for preparing chemically strengthened glass. The method includes introducing glass to be tempered and an ion sieve according to the first aspect into a salt bath for chemically strengthening glass that is free of impurity ions, and chemically strengthening the glass to be tempered to prepare chemically strengthened glass. This preparation method enables online impurity removal by the ion sieve, allowing the impurity removal process by the ion sieve to be performed simultaneously with the glass tempering process, eliminating the need to pause the tempering process or frequently replace the salt bath, thereby improving the production efficiency of chemically strengthened glass and reducing the production costs of chemically strengthened glass.

[0073] According to this preparation method, during the chemical strengthening process, the ion sieve of the present application continuously and stably adsorbs impurity ions from the ion exchange process in the salt bath, so that the content of impurity ions in the salt bath is always stably kept at a relatively low level, thereby ensuring the quality of the tempered glass. Furthermore, the ion sieve hardly undergoes significant crystalline phase transition, has a stable structure, does not release large amounts of impurities that contaminate the salt bath, and can prevent the occurrence of defects such as significant granularity on the surface of the finished tempered glass.

[0074] The salt bath without impurity ions is a completely new salt bath containing almost no impurity ions, that is, an initial salt bath that has not been used for chemical strengthening of glass.

[0075] The present application will now be described in more detail with reference to specific examples. [Example]

[0076] Example 1 Ion sieves are [ka] The values ​​and oxide compositions are shown in Table 1 below: [ka] However, the ion-sieving Raman spectrum shows a peak at 830-1230 cm -1 Q after Gaussian deconvolution fitting for the bands in the range 3 is the corresponding area of ​​Q 3 but Si-O in silicon-oxygen tetrahedrons with only one non-bridging oxygen - is a stretching vibration peak, [ka] However, the ion-sieving Raman spectrum shows a peak at 830-1230 cm -1 Q after Gaussian deconvolution fitting for the bands in the range 2 is the corresponding area of ​​Q 2 but Si-O in a silicon-oxygen tetrahedron with only two non-bridging oxygens - The initial XRD pattern of the ion sieve, i.e., the initial XRD pattern of the ion sieve that has not been used for salt bath impurity removal, is shown in Figure 1a.

[0077] The raw material components of the ion sieve were weighed and mixed uniformly according to the recipe shown in Table 1, and then melted at 1500°C for more than 1 hour to form a liquid, which was then water-quenched to form granular ion sieves with a particle size of 2 to 5 mm. The water-quenching temperature was 25°C.

[0078] Examples 2 to 4 Each was carried out with reference to Example 1, but differed from Example 1 only in that the formulation instructions for the ion sieve were different. [ka] The specific oxide content and the relationship between the oxide contents are controlled, as shown in Table 1. The initial XRD pattern of the ion sieve, i.e., the XRD pattern of the initial ion sieve before it was used to remove impurities from the salt bath, is shown in Figure 1a.

[0079] (Comparative Examples 1 to 4) Each was carried out with reference to Example 1, but differed from Example 1 only in that the formulation instructions for the ion sieve were different. [ka] The different oxide contents are achieved by controlling the content of each oxide and the relationship between the oxide contents, as detailed in Table 1. The initial XRD pattern of the ion sieve, i.e., the XRD pattern of the initial ion sieve before it was used to remove impurities from the salt bath, is shown in Figure 1b.

[0080] (Application example 1) The ion sieves obtained in each of the above examples and comparative examples were placed in a test salt bath containing 105±10 ppm of lithium ions at 480°C to perform a lithium ion adsorption reaction. The amount of the ion sieve used was 1 wt% of the weight of the test salt bath. In the above test salt bath, the change in lithium ion concentration y over time x is shown in Table 2 below and Figures 3a and 3b, and the fitting results of the change curves for Examples 1 to 4 are shown in Figures 4, 5, 6, and 7. After the ion sieve was adsorbed with lithium ions in the test salt bath for 24 hours, the crystalline content in the ion sieve was shown in Table 1. The crystalline content was expressed as the percentage of the crystalline peak area in the XRD pattern of the ion sieve after 24 hours of salt bath impurity removal. The XRD patterns of the ion sieves after 24 hours of salt bath impurity removal are shown in Figures 2a and 2b, respectively.

[0081] JPEG0007818627000021.jpg211141

[0082] JPEG0007818627000022.jpg242152

[0083] As can be seen from Tables 1 and 2, the ion sieves according to the examples of the present invention are all superior to the comparative examples. [ka] By using a formula in which the ion sieve's formula is greater than 1, it can continuously and stably adsorb lithium ions for 24 hours in a test salt bath at 480°C, and after 24 hours of adsorption of lithium ions, the crystalline content in the ion sieves is less than 10% by weight. As can be seen from this, the ion sieves according to the embodiments of the present invention have stable lithium ion absorption capacity in a high-temperature salt bath, undergo little or no crystalline phase transition in a high-temperature salt bath, and can maintain a stable structure for a long time, so that the long-term use of the ion sieve will not contaminate the high-temperature salt bath or shorten the life of the salt bath.

[0084] As can be seen from FIGS. 1a, 1b, 2a and 2b, after the ion sieve according to the embodiment of the invention of this application continuously removed impurities for 24 hours in a salt bath for testing at 480°C, almost no crystal phase transition occurred and a stable structure was maintained. In contrast, after the ion sieve according to the comparative example continuously removed impurities for 24 hours in a salt bath for testing at 480°C, a significant crystal phase transition occurred and many crystals not contained in the initial ion sieve were generated. As can be seen from this, the ion sieve according to the invention of this application having a specific composition and a specific structure has excellent high-temperature stability and can continuously remove impurity ions in a high-temperature salt bath for a long time.

[0085] As can be seen from FIGS. 3a, 3b and 4 to 7, after the ion sieve according to the embodiment was placed in a salt bath for testing at 480°C to remove lithium ion impurities, the change in the lithium ion concentration y in the salt bath with the passage of time x satisfied the function of y = A1×exp(-x / b1)+A2×exp(-x / b2)+C0, where 100 > A1 > 30, 0 < A2 < 31, 0 < b1 < 5, 0 < b2 < 25, and 0 < C0 < 50, and exp is an exponential function. As can be seen from this, the ion sieve having a specific composition and a specific structure according to the embodiment of the invention of this application can adsorb lithium ions continuously and stably for a long time in a high-temperature salt bath.

[0086] In contrast, the ion sieves of the comparative examples did not satisfy the above-mentioned function for the time change of lithium ion concentration in a salt bath at 480°C. For example, the fitting function corresponding to Comparative Example 2 was y = 29 × exp(-x / 1.52) - 10.92 × exp(x / 22.00) + 79.89. The ion sieves of Comparative Examples 1 and 4 released lithium ions back into the salt bath within 10 hours of impurity removal, thereby increasing the lithium ion concentration in the salt bath. In other words, the comparative examples did not satisfy the characteristics of the ion sieve having a specific composition and structure according to the present invention, and were unable to continuously and stably adsorb lithium ions for a long period of time in a high-temperature salt bath. Instead, lithium ions were released into the salt bath due to a change in structure in the latter half of the period.

[0087] (Application example 2) For Example 1, Comparative Example 1, and Comparative Example 2, an ion sieve and pre-tempered lithium aluminosilicate glass were simultaneously placed in a fresh sodium nitrate salt bath at 460°C and tempered in successive batches. The tempering time for each batch was 8 hours. After one batch of tempered glass was completed, the tempered glass and ion sieve were removed from the salt bath, and the next batch of pre-tempered glass and a new ion sieve were added. The amount of ion sieve added to the salt bath with the pre-tempered glass for each tempering run was 1% of the salt bath weight. Figures 8, 9, and 10 show the finished glass products obtained by tempering the eighth batch of glass in Example 1 and Comparative Examples 1 and 2, respectively.

[0088] As shown in Fig. 8, when salt bath impurity removal was performed using the ion sieve according to Example 1 of the present invention, the tempered glass had a smooth surface and was free of defects. In contrast, when salt bath impurity removal was performed using the ion sieves according to Comparative Examples 1 and 2, significant granular defects appeared on the surface of the tempered glass, as shown in the dotted circle in Figs. 9 and 10.

[0089] Although the above describes in detail the optional embodiments of the present invention, the present invention is not limited thereto. Within the scope of the technical idea of ​​the present invention, various simple modifications to the technical idea of ​​the present invention, such as combining the respective technical features in any other suitable manner, may be made. These simple modifications and combinations should also be considered as the content disclosed in this application, and all fall within the protection scope of the present invention. [Industrial Applicability]

[0090] This application relates to the technical field of ion sieves, particularly to the technical field of removing impurities from salt baths for chemically strengthening glass, and specifically to an ion sieve having high temperature resistance and high temperature stability, its preparation method, and use. The composition of the ion sieve, in terms of the mole percentage of each oxide in the ion sieve, includes 46-60 mol% of SiO2, 3-16 mol% of Al2O3, 0-3 mol% of YO3, and 33-45 mol% of R2O. R2O is an alkali metal oxide. The ion sieve is [ka] is greater than or equal to 1. The ion sieve of the present invention has excellent high-temperature resistance and stability, and even when placed in a high-temperature salt bath for a relatively long period of time, it hardly undergoes any significant crystalline phase transition, has a stable structure, does not release large amounts of impurities that contaminate the salt bath, and does not cause significant defects on the surface of the tempered glass product. The ion sieve of the present invention can continuously and stably adsorb impurity ions for 24 hours in a salt bath at 480°C.

[0091] The ion sieve having high temperature resistance and stability, its preparation method and use according to the present application are feasible and can be applied to various industrial applications, for example, the ion sieve having high temperature resistance and stability, its preparation method and use according to the present application can be applied to the technical field of ion sieving.

Claims

1. an ion sieve, The composition of the ion sieve is SiO ２ 46 to 60 mol%, Al ２ O ３ 3 to 16 mol %, Y ２ O ３ 0 to 3 mol % and R ２ O 33 to 45 mol %; R ２ O is Na ２ O, The ion sieve is [Equation 1] is greater than or equal to 1, [Equation 2] is 830-1230 cm in the ion sieving Raman spectrum －１ Q after Gaussian deconvolution fitting for the bands in the range ３ is the corresponding area of ​​Q ３ but Si—O in a silicon-oxygen tetrahedron with only one non-bridging oxygen － is a stretching vibration peak, [Equation 3] is 830-1230 cm in the ion sieving Raman spectrum －１ Q after Gaussian deconvolution fitting for the bands in the range ２ is the corresponding area of ​​Q ２ but Si—O in a silicon-oxygen tetrahedron with only two non-bridging oxygens － is a stretching vibration peak, The composition of the ion sieve is, in terms of mole percentage of each oxide in the ion sieve, 52.0≧0.85×SiO 2 +0.15×Al 2 O 3 +1.65×Y 2 O 3 ≧45.3; An ion sieve characterized by:

2. an ion sieve, The composition of the ion sieve is SiO ２ 46 to 60 mol%, Al ２ O ３ 3 to 16 mol %, Y ２ O ３ 0 to 3 mol % and R ２ O 33 to 45 mol %; R ２ O is Na ２ O and K ２ O, The ion sieve is [Equation 4] is greater than or equal to 1, [Equation 5] is 830-1230 cm in the ion sieving Raman spectrum －１ Q after Gaussian deconvolution fitting for the bands in the range ３ is the corresponding area of ​​Q ３ but Si—O in a silicon-oxygen tetrahedron with only one non-bridging oxygen － is a stretching vibration peak, [Equation 6] is 830-1230 cm in the ion sieving Raman spectrum －１ Q after Gaussian deconvolution fitting for the bands in the range ２ is the corresponding area of ​​Q ２ but Si—O in a silicon-oxygen tetrahedron with only two non-bridging oxygens － is a stretching vibration peak, The composition of the ion sieve is, in terms of mole percentage of each oxide in the ion sieve, 20.0 ≥ 0.50 × Na ２ Further satisfying O≧16.0, The composition of the ion sieve is, in terms of mole percentage of each oxide in the ion sieve, 52.0≧0.85×SiO 2 +0.15×Al 2 O 3 +1.65×Y 2 O 3 ≧45.3; An ion sieve characterized by:

3. After placing the ion sieve in a salt bath at 480°C for 24 hours, the content of crystals in the ion sieve is less than 10% by weight.

3. The ion sieve according to claim 1 or 2. [Request Item 4] [Number 7] 3. The ion sieve according to claim 1 or 2.

5. In the ion sieve, SiO ２ is 49 to 60 mole %; and / or Al ２ O ３ is 3 to 15 mole %; and / or Y ２ O ３ is 1 to 3 mole %; and / or R ２ The mole percentage of O is 33 to 40 mole % 3. The ion sieve according to claim 1 or 2.

6. The composition of the ion sieve is as follows: ZnO 0-3 mol %, CaO 0-3 mol %, MgO 0-3 mol %, P ２ O ５ 0 to 3 mol %, and B ２ O ３ Further containing 0 to 3 mol % of ZnO + CaO + MgO + P ２ O ５ +B ２ O ３ The sum of the mole percentages of 3. The ion sieve according to claim 1 or 2.

7. In the ion sieve, P ２ O ５ and / or B ２ O ３ Contains almost no 7. The ion sieve of claim 6.

8. When the ion sieve having a mass percentage of 1 wt. % based on the mass of the salt bath is placed in a salt bath at 480° C. containing 105±10 ppm of impurity lithium ions, The change curve of the lithium ion concentration y in the salt bath over time x is y = A １ ×exp(-x / b １ ) + A ２ ×exp(-x / b ２ ) + C ０ where exp is an exponential function and A １ is 100>A １ >30, A ２ is 0<A ２ <31, b １ is 0<b １ <5, b ２ is 0<b ２ <25, C ０ is 0<C ０ < 50 and x is in hours 3. The ion sieve according to claim 1 or 2.

9. 3. A method for preparing the ion sieve of claim 1 or 2, comprising the steps of: The preparation method includes the steps of weighing out each raw material according to the recipe, mixing them uniformly, melting them at a temperature of 1300-1650°C to obtain a liquid material, and then preparing it into a granular, sheet or porous form. A method for preparing an ion sieve, comprising:

10. The granular ion sieve is formed by water quenching, and the water quenching temperature is 10-80°C.

10. The method for preparing an ion sieve according to claim 9,

11. Forming sheet-like ion sieves by rolling or drawing with external force 10. The method for preparing an ion sieve according to claim 9,

12. Forming a porous ion sieve by introducing a foaming agent 10. The method for preparing an ion sieve according to claim 9,

13. The method includes a step of introducing the ion sieve according to claim 1 or 2 into a salt bath for impurity removal at 350 to 550°C to perform an adsorption reaction of impurity ions. A method for removing impurities from a salt bath for chemically strengthening glass, comprising:

14. The amount of the ion sieve used is 0.5 to 5.0% by weight of the salt bath for impurity removal, and / or the time of the adsorption reaction is 0.1 to 48.0 hours.

14. The method for removing impurities according to claim 13.

15. The content of impurity ions in the impurity removal salt bath is 1 to 1000 ppm.

15. The method for removing impurities according to claim 14.

16. The method includes a step of introducing glass to be tempered and the ion sieve according to claim 1 or 2 into a salt bath for chemically strengthening glass that is free of impurity ions, and chemically strengthening the glass to be tempered. A method for preparing chemically strengthened glass, comprising:

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