Low reflectance glass and methods of making and using the same

Abstract

The present disclosure provides a low reflectivity glass and a preparation method and application thereof, and the specific steps are as follows: a glass substrate is strengthened, lithium ions in the glass substrate are exchanged with sodium ions in the outside world, the exchange depth is d1, the sodium ions are exchanged with potassium ions in the outside world, the exchange depth is d2, and a low reflectivity glass is obtained; wherein, d1>d2, and the maximum optical path difference of the glass substrate is less than 2. Through the method of double ion exchange, a high-potassium strengthened layer and a high-sodium strengthened layer with gradient refractive index are formed on the surface of the glass, the reflection of light is reduced, the reflectivity of the glass is further reduced, and the scratch resistance of the glass is improved. The low reflectivity glass prepared by the present disclosure can reach a reflectivity of less than 8.1% at 550 nm when the thickness is 1.3 mm, and also has good scratch resistance, and the scratch width is less than 100 mu m when the load is 1 kg.

Description

Technical Field

[0001] This disclosure relates to the field of glass manufacturing technology, and in particular to a low-reflectivity glass, its preparation method, and its application. Background Technology

[0002] Electronic devices with screens, such as mobile phones, tablets, and car navigation systems, are becoming increasingly common in people's lives. However, when exposed to strong sunlight, the reflected light from the screens of these devices can significantly reduce their display quality and negatively impact the user experience.

[0003] Covering the screen of electronic devices with a low-reflectivity glass cover can reduce reflected light and improve the user experience. Since the glass cover is subject to constant human-computer interaction during use, good scratch resistance is essential to prevent scratches and other damage. Therefore, in addition to low reflectivity, the glass cover also needs to have excellent scratch resistance.

[0004] In existing technologies, the reflectivity of glass is often reduced through coating or etching. However, after coating, interfacial reflection exists between the film layer and the glass substrate, resulting in limited reduction in reflectivity, and the process is relatively complex. While etching can effectively reduce the reflectivity of glass, it affects the surface strength of the glass and reduces its scratch resistance. Summary of the Invention

[0005] One of the technical problems this disclosure aims to solve is: how to reduce the reflectivity of glass and improve its scratch resistance, thereby making it more suitable for practical use.

[0006] The technical problem addressed in this disclosure is solved by the following technical solution.

[0007] This disclosure provides a method for preparing low-reflectivity glass, which involves strengthening a glass substrate to allow lithium ions in the glass substrate to exchange with sodium ions from the outside environment at a depth of d1, and sodium ions to exchange with potassium ions from the outside environment at a depth of d2, thereby obtaining low-reflectivity glass; wherein d1 > d2; and the maximum optical path difference of the aforementioned glass substrate is less than 2.

[0008] In some embodiments, d1 ranges from 10 to 12 μm, and d2 ranges from 3 to 5 μm.

[0009] In some embodiments, the method for strengthening the aforementioned glass substrate is as follows: immersing the aforementioned glass substrate in NaNO3 molten salt at 400-470°C for 1-5 hours, and then immersing it in KNO3 molten salt at 380-450°C for 0.25-3 hours.

[0010] In some embodiments, the aforementioned glass substrate is immersed in NaNO3 molten salt at 400-450°C for 2-5 hours, and then immersed in KNO3 molten salt at 380-435°C for 0.25-1.5 hours.

[0011] In some embodiments, the method for strengthening the aforementioned glass substrate is to immerse the aforementioned glass substrate in a mixed molten salt at 400-470°C for 4-8 hours; the aforementioned mixed molten salt includes 3-10% KNO3 and 90-97% NaNO3.

[0012] In some embodiments, the aforementioned glass substrate is immersed in a mixed molten salt at 420-450°C for ion exchange for 4-6 hours.

[0013] In some embodiments, the aforementioned glass substrate components, by mass percentage of oxides, are: Li2O: 4-7%; and Na2O: 4-8%.

[0014] In some embodiments, the aforementioned glass substrate components, by mass percentage of oxides,

[0015] SiO2: 55-67%;

[0016] Al2O3: 16-25%;

[0017] B2O3: 2-6%;

[0018] ZrO2: 0.5-2%;

[0019] BeO: 0.5-2%;

[0020] K2O: 0-3%;

[0021] MgO: 0-3%;

[0022] CaO: 0-1%;

[0023] SrO: 0-2%; and,

[0024] ZnO: 0-2%.

[0025] The present disclosure also employs the following technical solutions to address its technical problems.

[0026] This disclosure provides a low-reflectivity glass, comprising:

[0027] Glass substrate;

[0028] A high-sodium strengthening layer is disposed on the surface of the aforementioned glass substrate; the aforementioned high-sodium strengthening layer is a glass in which some lithium ions in the aforementioned glass substrate are exchanged with external sodium ions; and,

[0029] A high-potassium strengthening layer is disposed on the surface of the aforementioned high-sodium strengthening layer; the aforementioned high-potassium strengthening layer is glass in which some sodium ions in the aforementioned high-sodium strengthening layer have been exchanged with external potassium ions.

[0030] The present disclosure also employs the following technical solutions to address its technical problems.

[0031] This disclosure provides a screen cover comprising the aforementioned low-reflectivity glass.

[0032] By employing the above technical solutions, the low-reflectivity glass, its preparation method, and its applications provided in this disclosure have at least the following advantages:

[0033] This disclosure employs a dual ion exchange method to strengthen a glass substrate, forming two distinct strengthening layers on the glass surface: a high-potassium strengthening layer, a high-sodium strengthening layer, and the glass substrate itself, from the outside in. The high-sodium strengthening layer is obtained by exchanging lithium ions from the glass substrate with sodium ions from the surrounding environment; the high-potassium strengthening layer is obtained by exchanging sodium ions from the high-sodium strengthening layer with potassium ions from the surrounding environment. It is important to note that different elements in the glass have different effects on the refractive index. The closer to the glass surface, the higher the concentration of exchanged ions, and the greater the impact on the refractive index; conversely, the closer to the glass substrate, the lower the concentration of exchanged ions, and the smaller the impact on the refractive index. Therefore, both the high-sodium and high-potassium strengthening layers are gradient refractive index strengthening layers, meaning that the refractive index of both strengthening layers gradually changes with depth. Furthermore, because the refractive index is gradual, there is no clear interface between the two strengthening layers and the glass substrate, and therefore no interface reflection.

[0034] In glass, the refractive indices of Li, Na, and K are ranked as follows: K > Li > Na. In the high-potassium (K) strengthening layer, the potassium ion concentration gradually decreases from the outside in, while the sodium ion concentration gradually increases, resulting in a decrease in refractive index. Conversely, in the high-sodium (S) strengthening layer, the sodium ion concentration gradually decreases from the outside in, while the lithium ion concentration gradually increases, resulting in a increase in refractive index. The applicant argues that when light enters the high-K strengthening layer, this gradual refractive index structure causes the light to repeatedly undergo refraction-reflection-refraction until it exits, significantly reducing light reflection compared to a homogeneous medium. Furthermore, the gradual refractive index structure in the high-sodium strengthening layer allows more light incident at large angles to ultimately penetrate the substrate, greatly increasing transmittance. Through the combined effect of these two different gradient refractive index strengthening layers, the reflectivity of the glass is further reduced, and the high-K strengthening layer significantly increases the surface hardness of the glass. The low-reflectivity glass prepared by the method disclosed herein can achieve a reflectivity of less than 8.1% at 550 nm when the thickness is 1.3 mm, and also has good scratch resistance, with a scratch width of less than 100 μm when loaded with 1 kg.

[0035] The above description is only an overview of the technical solution of this disclosure. In order to better understand the technical means of this disclosure and to implement it in accordance with the contents of the specification, the preferred embodiments of this disclosure are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of the low-reflectivity glass disclosed in this embodiment.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. High-potassium reinforcing layer; 2. High-sodium reinforcing layer; 3. Glass substrate. Detailed Implementation

[0040] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0041] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0042] It should be noted that, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0043] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.

[0044] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure depending on the specific circumstances. When a particular device is described as being located between a first device and a second device, an intermediary device may or may not be present between the particular device and the first or second device.

[0045] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0046] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0047] This disclosure provides a method for preparing low-reflectivity glass, the specific steps of which are: strengthening the glass substrate, so that lithium ions in the glass substrate exchange with sodium ions in the outside world at an exchange depth of d1, and sodium ions exchange with potassium ions in the outside world at an exchange depth of d2, thereby obtaining low-reflectivity glass; wherein d1 > d2; and the maximum optical path difference of the glass substrate is less than 2.

[0048] This disclosure employs a double ion exchange method to strengthen the glass substrate, forming two different strengthening layers on the glass surface, resulting in low-reflectivity glass such as... Figure 1As shown, from the outside in, the layers are, in order: a high-potassium strengthening layer 1, a high-sodium strengthening layer 2, and a glass substrate 3. The high-sodium strengthening layer 2 is obtained by exchanging lithium ions in the glass substrate with sodium ions from the surrounding environment; the high-potassium strengthening layer 1 is obtained by exchanging sodium ions in the high-sodium strengthening layer 2 with potassium ions from the surrounding environment. It is important to note that different elements in the glass have different effects on the refractive index. The closer to the glass surface, the higher the concentration of exchanged ions, and the greater the impact on the refractive index; the closer to the glass substrate 3, the lower the concentration of exchanged ions, and the smaller the impact on the refractive index. Therefore, both the high-sodium strengthening layer 2 and the high-potassium strengthening layer 1 are gradient refractive index strengthening layers, meaning that the refractive index of both strengthening layers gradually changes with depth. Furthermore, because the refractive index is gradual, there is no clear interface between the two strengthening layers and the glass substrate 3, and therefore no interface reflection.

[0049] In glass, the refractive indices of Li, Na, and K are ranked as follows: K > Li > Na. In high-potassium strengthening layer 1, the potassium ion concentration gradually decreases from the outside in, while the sodium ion concentration gradually increases, resulting in a change in refractive index from high to low. In high-sodium strengthening layer 2, the sodium ion concentration gradually decreases from the outside in, while the lithium ion concentration gradually increases, resulting in a change in refractive index from low to high. When light enters high-potassium strengthening layer 1, this gradual refractive index structure causes the light to repeatedly undergo refraction-reflection-refraction until it exits, significantly reducing light reflection compared to a homogeneous medium. When light enters high-sodium strengthening layer 2, this gradual refractive index structure allows more light incident at large angles to ultimately penetrate the substrate, greatly improving transmittance. Through the combined effect of these two different gradient refractive index strengthening layers, the reflectivity of the glass is further reduced, and the high-potassium strengthening layer significantly increases the surface hardness of the glass.

[0050] In addition, the maximum optical path difference of the glass substrate is less than 2, which makes the glass substrate have a relatively uniform reflectivity, thereby ensuring that the strengthening layer forms a gradient refractive index.

[0051] In some embodiments, d1 ranges from 10 to 12 μm, and d2 ranges from 3 to 5 μm. An exchange depth d1 between lithium ions and external sodium ions is less than 10 μm, which is ineffective in reducing glass reflectivity. A depth greater than 12 μm significantly reduces the scratch resistance and drop resistance of the resulting low-reflectivity glass. Therefore, d1 is controlled within the range of 10 to 12 μm. Similarly, an exchange depth d2 between sodium ions and external potassium ions is less than 3 μm, which is ineffective in reducing glass reflectivity and results in poor scratch resistance. A depth greater than 5 μm makes the high-potassium strengthening layer 1 too thick and the high-sodium strengthening layer 2 too thin, thus failing to effectively reduce glass reflectivity. Therefore, d2 is controlled within the range of 3 to 5 μm.

[0052] In some embodiments, the method for strengthening the aforementioned glass substrate is as follows: immersing the aforementioned glass substrate in NaNO3 molten salt at 400-470°C for 1-5 hours, and then immersing it in KNO3 molten salt at 380-450°C for 0.25-3 hours.

[0053] When the temperature of NaNO3 molten salt is below 400℃, the exchange between sodium and lithium ions is slow and cannot reach the required depth. When the temperature of NaNO3 molten salt is above 470℃, it will cause increased tensile stress in the glass, significantly reducing its scratch resistance and drop resistance. Therefore, the strengthening temperature of sodium salt should be controlled between 400-470℃. If the strengthening time of NaNO3 molten salt is less than 1 hour, the exchange between sodium and lithium ions cannot reach the required depth. If the strengthening time of NaNO3 molten salt is more than 5 hours, it will cause increased tensile stress in the glass, significantly reducing its scratch resistance and drop resistance. Therefore, the strengthening time of sodium salt should be controlled between 1-5 hours. When the temperature of KNO3 molten salt is below 380℃, the exchange between potassium and sodium ions is slow and cannot reach the required depth. When the temperature of KNO3 molten salt is above 450℃, it will cause increased tensile stress in the glass, significantly reducing its scratch resistance and drop resistance. Therefore, the strengthening temperature of potassium salt should be controlled between 380-450℃. If the KNO3 molten salt strengthening time is less than 0.25h, the exchange between potassium and sodium ions cannot reach the required depth. If the KNO3 molten salt strengthening time is more than 3h, the exchange depth between potassium and sodium ions will be too deep, resulting in a poor reduction in reflectivity. Therefore, the potassium salt strengthening time should be controlled between 0.25-3h.

[0054] In some embodiments, the aforementioned glass substrate is immersed in NaNO3 molten salt at 400-450°C for 2-5 hours, and then immersed in KNO3 molten salt at 380-435°C for 0.25-1.5 hours. Low-reflectivity glass prepared using this temperature and time range has lower reflectivity and better scratch resistance.

[0055] In some embodiments, the method for strengthening the aforementioned glass substrate is to immerse the aforementioned glass substrate in a mixed molten salt at 400-470°C for 4-8 hours; the aforementioned mixed molten salt includes 3-10% KNO3 and 90-97% NaNO3.

[0056] The objectives of this disclosure can be achieved by employing either a two-stage strengthening method or a mixed strengthening method. When strengthening a glass substrate using a mixed molten salt, excessively low temperatures or short durations result in shallow ion exchange depths, while excessively high temperatures or long durations lead to increased tensile stress in the glass, significantly reducing its scratch resistance and drop resistance. Therefore, the temperature for mixed molten salt strengthening is controlled at 400-470℃, and the time at 4-8 hours. The mixed molten salt consists of 3-10% KNO3 and 90-97% NaNO3. Low-reflectivity glass produced within this range exhibits relatively low reflectivity.

[0057] In some embodiments, the aforementioned glass substrate is immersed in a mixed molten salt at 420-450°C for ion exchange for 4-6 hours. Low-reflectivity glass produced within this range exhibits relatively low reflectivity.

[0058] In some embodiments, the aforementioned glass substrate components, by mass percentage of oxides, are: Li2O: 4-7%; and Na2O: 4-8%.

[0059] Li₂O is an ion-exchange component, particularly essential for achieving deeper stress depths by exchanging Li ions in the glass with Na ions in the molten salt. Additionally, Li₂O reduces the high-temperature viscosity of glass and increases Young's modulus. However, high Li₂O content increases the erosion of the refractory materials in the furnace, reducing its service life. Therefore, in this disclosure, the Li₂O content is limited to 4-7%.

[0060] Sodium ion exchange (Na₂O) is an ion-exchange component that increases the compressive stress on the glass surface by exchanging sodium ions for potassium ions. It is also a necessary component for forming layers with different refractive indices. Additionally, Na₂O reduces viscosity at high temperatures, thereby improving meltability and formability. If the Na₂O content is too low, meltability decreases, and the ion exchange rate slows down. If the Na₂O content is too high, the scratch resistance and surface compressive stress of the glass will decrease significantly. Therefore, its content is limited to 4-8%.

[0061] In some embodiments, the aforementioned glass substrate components, by mass percentage of oxides,

[0062] SiO2: 55-67%;

[0063] Al2O3: 16-25%;

[0064] B2O3: 2-6%;

[0065] ZrO2: 0.5-2%;

[0066] BeO: 0.5-2%;

[0067] K2O: 0-3%;

[0068] MgO: 0-3%;

[0069] CaO: 0-1%;

[0070] SrO: 0-2%; and,

[0071] ZnO: 0-2%.

[0072] SiO2 is the network forging material and a major component of the glass skeleton. When the SiO2 content is too low, the resulting glass has low strength, reduced overall transmittance, and increased reflectivity; when the SiO2 content is too high, the glass is difficult to melt and form. Therefore, when the SiO2 content is between 55-67%, the glass exhibits good mechanical properties and a relatively low reflectivity.

[0073] Al₂O₃ can improve the heat resistance and chemical durability of glass. Simultaneously, it increases the internal porosity of the glass, allowing alkali metal ions to move freely and facilitating their exchange, thus increasing the surface compressive stress after glass strengthening. When the Al₂O₃ content in the glass is low, the durability and surface compressive stress decrease, and scratch resistance is reduced. When the Al₂O₃ content exceeds a certain amount, the viscosity of the molten glass increases, making it difficult to clarify. Therefore, the Al₂O₃ content in this disclosure is limited to 16-25%.

[0074] The glass disclosed herein contains 16-25% Al2O3, which leads to an increased melting temperature. Therefore, introducing B2O3 as a flux can increase the low-temperature viscosity of the glass. Furthermore, it improves the glass's scratch resistance and crack resistance, while also increasing light transmittance and reducing reflectivity. However, excessive B2O3 significantly reduces the glass's toughness and ion exchange rate, thus diminishing the strengthened glass's performance. Therefore, the B2O3 content is limited to 2-6%.

[0075] ZrO2 can improve the transparency of glass, increase its transmittance, and reduce its reflectivity. During chemical strengthening, it can increase the compressive stress on the glass surface and improve scratch resistance. However, excessive Zr content can increase the glass melting temperature and cause Zr crystals to precipitate during glass forming, affecting glass quality. Therefore, the ZrO2 content is limited to 0.5-2%.

[0076] While Be (Be) has a small atomic weight, its oxide, BeO, possesses high strength among all alkaline earth metal oxides. It can also lower the melting temperature, forming viscosity, and coefficient of thermal expansion of glass, reducing reflectivity and increasing transmittance. Therefore, BeO offers unique advantages for glass seeking to reduce reflectivity. Furthermore, a certain amount of BeO can improve the annealing quality of glass and increase its scratch resistance. However, BeO also has significant drawbacks. Its high melting point means that adding too much BeO not only increases production costs but also complicates the glass melting process. Therefore, the BeO content is limited to 0.5-2%.

[0077] K₂O is a component used to reduce viscosity at high temperatures, thereby improving meltability and formability; its effect is essentially the same as that of Na₂O. Na₂O and K₂O can exist simultaneously or separately. Therefore, in this disclosure, the content of K₂O is limited to 0-3%.

[0078] Excessive MgO content increases the devitrification of glass; therefore, the MgO content is limited to 0-3%. Excessive CaO content increases the brittleness of glass and is detrimental to potassium and sodium ion exchange; therefore, the CaO content is limited to 0-1%. Excessive SrO content increases the density of glass, as well as its refractive index and reflectivity; therefore, the SrO content is limited to 0-2%.

[0079] ZnO can improve the mechanical properties of glass and increase its Young's modulus. It can also reduce the high-temperature melting viscosity of glass, making it easier to form. However, excessive ZnO can significantly increase the refractive index and reflectivity of glass. Therefore, the ZnO content is limited to 0-2%.

[0080] In some embodiments, the aforementioned aluminosilicate glass has the following composition by mass percentage of oxides: total alkali metal oxide content M: 10-14%, total alkaline earth metal oxide content N: 1%-5%.

[0081] Alkali metal oxides can reduce the high-temperature viscosity of glass and improve its meltability and formability. However, if the content of alkali metal oxides M ([Li₂O] + [Na₂O] + [K₂O]) is too high, the coefficient of thermal expansion of the glass increases, and its scratch resistance decreases. Therefore, the suitable range for the content of alkali metal oxides M is 10-14%.

[0082] The addition of alkaline earth metal oxides (BeO, MgO, CaO, SrO) can effectively reduce the high-temperature viscosity of glass, thereby improving its melt permeability and formability, and also enhancing its scratch resistance. However, excessive content of alkaline earth metal oxides will increase the glass density, refractive index, and reflectivity, while decreasing its scratch resistance. Therefore, the total amount of alkaline earth metal oxides, N, is limited to 1-5%.

[0083] In some embodiments, the aforementioned aluminosilicate glass has the following composition by mass percentage of oxides: 0.3 ≤ Li2O / M ≤ 0.6, 0.5 ≤ (M+N) / Al2O3 ≤ 1, and 0.2 ≤ BeO / N ≤ 1.

[0084] The applicant found in the study that when the alkali metal and alkaline earth metal satisfy 0.3≤Li2O / M≤0.6, 0.5≤(M+N) / Al2O3≤1, and 0.2≤BeO / N≤1, the glass has good melting properties and scratch resistance, and exhibits low reflectivity.

[0085] In some embodiments, the aforementioned aluminosilicate glass, wherein the glass composition, by mass percentage of oxides, is ZrO2:BeO = 1:0.3-1.3.

[0086] The applicant found in the study that ZrO2 and BeO work together to reduce the reflectivity of glass. When the mass ratio of the two as oxides is ZrO2:BeO = 1:0.3-1.3, the glass exhibits a lower reflectivity.

[0087] This disclosure provides a low-reflectivity glass, such as... Figure 1 As shown, it includes:

[0088] Glass substrate 3;

[0089] A high-sodium strengthening layer 2 is disposed on the surface of the aforementioned glass substrate; the aforementioned high-sodium strengthening layer is a glass in which some lithium ions in the aforementioned glass substrate are exchanged with external sodium ions; and,

[0090] A high-potassium strengthening layer 1 is disposed on the surface of the aforementioned high-sodium strengthening layer; the aforementioned high-potassium strengthening layer is glass in which some sodium ions in the aforementioned high-sodium strengthening layer have been exchanged with external potassium ions.

[0091] The present disclosure also employs the following technical solutions to address its technical problems.

[0092] This disclosure provides a screen cover comprising the aforementioned low-reflectivity glass. This screen cover can be used on the displays of various electronic devices such as mobile phones, computers, or automotive displays.

[0093] This disclosure also proposes an electronic device that includes the aforementioned screen cover. The electronic device is a mobile phone, tablet computer, car navigation system, or other electronic device with a screen.

[0094] The present disclosure will be further described below with reference to specific embodiments, but it should not be construed as a limitation on the scope of protection of the present disclosure. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present disclosure are still within the scope of protection of the present disclosure.

[0095] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains.

[0096] Examples 1-8

[0097] According to the proportions in the table, calculate and weigh the raw materials corresponding to each component (all component masses are converted to oxides). After thorough stirring, the raw materials are fed into a melting furnace. After melting, clarifying, shaping, annealing, and cutting, a glass substrate with a thickness of 1.3 mm is prepared, and the maximum optical path difference of the glass substrate is less than 2. The reflectivity F1 of the glass is measured, and the measured values ​​are shown in Table 1.

[0098] The aforementioned glass substrate was first strengthened once, then strengthened twice to obtain low-reflectivity glass. The first strengthening method involved preheating the glass substrate and immersing it in 100% NaNO3 molten salt; the temperature and duration of the first strengthening in each embodiment are shown in Table 1. The second strengthening method involved preheating the first-strengthened glass substrate and immersing it in 100% KNO3 molten salt to obtain low-reflectivity glass; the temperature and duration of the two strengthening processes in each embodiment are shown in Table 1. The reflectivity F2 and scratch width at a 1kg load of the low-reflectivity glass in each embodiment were measured, and the measured values ​​are shown in Table 1.

[0099] Table 1. Raw materials, experimental parameters, and glass performance measurement results for Examples 1-8

[0100]

[0101] Examples 9-16

[0102] According to the proportions in the table, the raw materials corresponding to each component were calculated and weighed (all component masses are converted to oxides). After thorough stirring, the raw materials were fed into a melting furnace. After melting, clarifying, shaping, annealing, and cutting, a glass substrate with a thickness of 1.3 mm was prepared, and the maximum optical path difference of the glass substrate was less than 2. The reflectance F1 at 550 nm of the glass substrate was measured, and the measured values ​​are shown in Table 2.

[0103] The aforementioned glass substrate was first subjected to hybrid strengthening to obtain low-reflectivity glass. The hybrid strengthening method was as follows: the glass substrate was preheated and then immersed in a mixed molten salt of NaNO3 and KNO3; the ratio of NaNO3 to KNO3 in the mixed molten salt of each embodiment is shown in Table 2; the temperature and duration of hybrid strengthening of each embodiment are shown in Table 2. The reflectivity F2 of the low-reflectivity glass at 550 nm and the scratch width under a load of 1 kg were measured in each embodiment, and the measured values ​​are shown in Table 2.

[0104] Table 2. Raw materials, experimental parameters, and glass performance measurement results for Examples 9-16

[0105]

[0106] According to the experimental results of Examples 1-16, the reflectance F1 of the 1.3 mm thick glass substrate prepared in Examples 1-16 at 550 nm is less than 8.3%; the reflectance F2 of the low reflectance glass prepared after strengthening the glass substrate is less than 8.1% at 550 nm, and F2–F1 is greater than 0.2%. Moreover, the strengthened glass has good scratch resistance, and the scratch width is less than 100 μm when loaded with 1 kg.

[0107] Comparative Example 1

[0108] The difference between Comparative Example 1 and Example 4 is that both strengthening methods used NaNO3 molten salt.

[0109] Comparative Example 2

[0110] The difference between Comparative Example 2 and Example 4 is that both strengthening methods used KNO3 molten salt.

[0111] Comparative Example 3

[0112] The difference between Comparative Example 3 and Example 4 is that the maximum optical path difference of the glass substrate used is 5.

[0113] Table 3 shows the data for the 550nm reflectance F2, d1, d2 and scratch width of the 1.3mm thick low-reflectivity glass prepared in Comparative Examples 1-2.

[0114] Table 3. Measurement data of low-reflectivity glass in Comparative Examples 1-2

[0115]

[0116] As can be seen from Comparative Examples 1-2, the double ion exchange method disclosed in this paper forms a high-potassium strengthening layer and a high-sodium strengthening layer with gradient refractive index on the glass surface, which can reduce light reflection, further reduce the reflectivity of the glass, and improve the scratch resistance of the glass.

[0117] The technical features in the claims and / or specification of this disclosure can be combined, and the combination is not limited to the combinations obtained through reference in the claims. Technical solutions obtained by combining the technical features in the claims and / or specification are also within the scope of protection of this disclosure.

[0118] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this disclosure shall still fall within the scope of the technical solution of this disclosure.

Claims

1. A method for preparing low-reflectivity glass, characterized in that, The glass substrate is strengthened so that lithium ions in the glass substrate exchange with sodium ions in the outside world at an exchange depth of d1, and sodium ions exchange with potassium ions in the outside world at an exchange depth of d2, to obtain low reflectivity glass; wherein d1 > d2; and the maximum optical path difference of the glass substrate is less than 2. The range of d1 is 10-12 μm, and the range of d2 is 3-5 μm.

2. The preparation method according to claim 1, characterized in that, The method for strengthening the glass substrate is as follows: immerse the glass substrate in NaNO3 molten salt at 400-470℃ for 1-5 hours, and then immerse it in KNO3 molten salt at 380-450℃ for 0.25-3 hours.

3. The preparation method according to claim 2, characterized in that, The glass substrate is immersed in NaNO3 molten salt at 400-450℃ for 2-5 hours, and then immersed in KNO3 molten salt at 380-435℃ for 0.25-1.5 hours.

4. The method according to claim 1, characterized in that, The method for strengthening the glass substrate is as follows: immersing the glass substrate in a mixed molten salt at 400-470°C for 4-8 hours; the mixed molten salt includes 3-10% KNO3 and 90-97% NaNO3.

5. The method according to claim 4, characterized in that, The glass substrate is immersed in a mixed molten salt at 420-450°C for ion exchange for 4-6 hours.

6. The preparation method according to claim 1, characterized in that, The glass substrate composition, by mass percentage of oxides, is: Li2O: 4-7%; and Na2O: 4-8%.

7. The preparation method according to claim 6, characterized in that, The glass substrate composition, by mass percentage of oxides, is... SiO2: 55-67%; Al2O3: 16-25%; B2O3: 2-6%; ZrO2: 0.5-2%; BeO: 0.5-2%; K2O: 0-3%; MgO: 0-3%; CaO: 0-1%; SrO: 0-2%; as well as, ZnO: 0-2%.

8. A low-reflectivity glass prepared by the method according to any one of claims 1-7, characterized in that, include: Glass substrate; A high-sodium reinforcement layer is disposed on the surface of the glass substrate; The high-sodium strengthening layer is a glass in which some lithium ions in the glass substrate have been exchanged with external sodium ions; as well as, A high-potassium strengthening layer is disposed on the surface of the high-sodium strengthening layer; the high-potassium strengthening layer is glass in which some sodium ions in the high-sodium strengthening layer have been exchanged with potassium ions from the outside; the thickness of the high-sodium strengthening layer is 10-12 μm, and the thickness of the high-potassium strengthening layer is 3-5 μm.

9. A screen cover, characterized in that, It includes the low-reflectivity glass as described in claim 8.

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