Microcrystalline glass cover plate and preparation method, repair and anti-fingerprint method, and electronic equipment

Abstract

The present application provides a microcrystalline glass cover plate, which is obtained by chemical ion exchange strengthening treatment of microcrystalline glass sheets. The molten salt used in the strengthening treatment contains LiNO3, which can enhance the surface stress and improve the strength while ensuring the stability of the surface state. The microcrystalline glass cover plate includes: a glass phase, accounting for 10%-70% by volume; a quartz crystal, accounting for 10%-55% by volume; a lithium disilicate crystal, accounting for 10%-40% by volume; and a lithium feldspar crystal, accounting for 10%-40% by volume. The present application also provides a preparation method of the microcrystalline glass cover plate, an electronic device using the microcrystalline glass cover plate, a repair method of the microcrystalline glass cover plate, and an anti-fingerprint method of the microcrystalline glass cover plate. The microcrystalline glass cover plate of the present application has high strength and excellent drop resistance, and its transparency and optical properties meet the screen use requirements of electronic devices such as mobile phones.

Description

Technical Field

[0001] The present application relates to a microcrystalline glass cover plate and a preparation method thereof, a repair method of the microcrystalline glass cover plate and an anti-fingerprint method of the microcrystalline glass cover plate, and an electronic device using the microcrystalline glass cover plate. Background Art

[0002] Compared with metal and plastic back covers / shells, transparent glass as the back cover / shell of various electronic devices such as mobile phones has better appearance, better touch, stronger decorativeness, and higher sense of technology. In addition, compared with metal materials, glass materials have less shielding of electromagnetic waves. With the advent of the 5G era, this has also become an advantage of glass materials. However, as a brittle material, glass is prone to cracking when used in electronic devices. Summary of the invention

[0003] In a first aspect, an embodiment of the present application provides a microcrystalline glass cover plate, which is obtained by strengthening a microcrystalline glass sheet through chemical ion exchange, wherein the molten salt used in the strengthening treatment contains LiNO3;

[0004] The microcrystalline glass cover plate comprises:

[0005] Glass phase, accounting for 15%-70% by volume;

[0006] Quartz crystal, accounting for 10%-55% by volume;

[0007] Lithium disilicate, crystal volume accounts for 10%-40%;

[0008] Petalite, crystal volume accounts for 10%-40%.

[0009] The strengthening process of the microcrystalline glass cover plate includes two ion exchanges. The LiNO3 component is added to the strengthening furnace water ratio. While enhancing the surface stress and improving the strength, the surface state can also be ensured to be stable, thereby obtaining a microcrystalline glass cover plate with high strength, excellent anti-drop performance, and optical properties that meet the requirements of display screen use. The reason for adding LiNO3 is that compared with conventional glass, microcrystalline glass contains a certain proportion of crystal phase. This characteristic makes the microcrystalline glass chemically strengthened. In addition to the glass phase, some ions in the surface crystal phase will also participate, thereby destroying the surface crystal phase and forming loose cavities on the surface. The exchanged Na ions and K ions are enriched in them. Under high temperature and high humidity environment, these ions and water vapor form white Na salts and K salts, which adhere to the glass surface and affect the cleanliness and display effect of the material. On the one hand, adding LiNO3 can inhibit the damage to the surface crystals during the strengthening process; on the other hand, it can reduce the Na ions and K ions enriched on the surface, so that the material can maintain the stability of surface performance under high temperature and high humidity environment.

[0010] In the implementation manner of the present application, the formula of the microcrystalline glass cover plate is:

[0011] SiO2 weight ratio 65%-85%,

[0012] Al2O3 weight ratio 5%-12%,

[0013] Na2O weight ratio 0.5-6%,

[0014] Li2O weight ratio 4%-9%,

[0015] P2O5 weight ratio 0.05%-3%,

[0016] K2O weight ratio 0.5%-3%,

[0017] MgO weight ratio 0.5%-8%,

[0018] TiO2 weight ratio 0.5%-3%,

[0019] ZrO2 weight ratio 0.1%-3%.

[0020] In the implementation manner of the present application, the microcrystalline glass cover plate is obtained by hot bending and strengthening treatment of a microcrystalline glass sheet and chemical ion exchange.

[0021] The 3D hot bending process promotes the formation of lithium disilicate crystals and petalite crystals, increases the number of lithium disilicate crystals and petalite crystals in the glass-ceramic sheet, and optimizes the optical performance and improves the strength. The raman spectrum test results before and after hot bending show that during the hot bending process, along with the breaking of the Si-O non-bridging oxygen bond, silicon and oxygen combine with Li, Al, etc. to form lithium disilicate crystals and petalite crystals.

[0022] In the embodiment of the present application, the strengthening treatment includes two ion exchanges; the first ion exchange: the molten salt composition is 0mol%-50mol% KNO3, 50mol%-100mol% NaNO3 and 0mol%-5mol% LiNO3, and the molten salt temperature is 400℃-480℃; the second ion exchange: the molten salt composition is KNO3 and LiNO3 with a weight of 0.05%-5% of the weight of KNO3, and the molten salt temperature is 350℃-420℃.

[0023] In the embodiment of the present application, after the strengthening treatment, the surface layer of the microcrystalline glass sheet is transformed into a strengthening layer, the thickness of the strengthening layer is greater than or equal to 90 microns, the surface compressive stress of the strengthening layer is ≥160MPa, and the compressive stress at a depth of 50 microns from the outer surface is ≥65MPa.

[0024] In the embodiment of the present application, the crystal size of the quartz crystal, the lithium disilicate crystal and the petalite crystal are all less than 80 nm, preferably less than 50 nm.

[0025] In the implementation manner of the present application, the average transmittance of the microcrystalline glass cover plate to light in the wavelength range of 450nm-1000nm is greater than or equal to 88%.

[0026] In the implementation manner of the present application, the haze of the microcrystalline glass cover plate is ≤0.2%, preferably ≤0.15%.

[0027] In the embodiment of the present application, the color difference b value of the microcrystalline glass cover plate satisfies |b|≤1.2, preferably |b|≤0.8.

[0028] In the embodiment of the present application, the four-bar bending strength B10 of the microcrystalline glass cover plate is greater than 550 MPa, and the average value is greater than 800 MPa.

[0029] In the implementation manner of the present application, the microcrystalline glass cover plate can withstand a single falling ball energy greater than 0.2J.

[0030] In the implementation manner of the present application, the microcrystalline glass cover plate is assembled on a whole machine including the microcrystalline glass cover plate weighing 180g, and has the whole machine sandpaper drop and marble drop strength above a height of 1.5m.

[0031] A second aspect of an embodiment of the present application provides an electronic device, comprising a transparent screen display cover plate and a shell, wherein at least one of the screen display cover plate and the shell is the microcrystalline glass cover plate described in the first aspect of the present application.

[0032] Since the above-mentioned microcrystalline glass cover plate has high strength and excellent drop resistance, the service life of the electronic device can be effectively improved.

[0033] A third aspect of the embodiments of the present application provides a method for preparing a microcrystalline glass cover plate, comprising:

[0034] The following raw materials are melted at 1300 to 1700°C to obtain glass stock solution:

[0035] SiO2 weight ratio 65%-85%,

[0036] Al2O3 weight ratio 5%-12%,

[0037] Na2O weight ratio 0.5-6%,

[0038] Li2O weight ratio 4%-9%,

[0039] P2O5 weight ratio 0.05%-3%,

[0040] K2O weight ratio 0.5%-3%,

[0041] MgO weight ratio 0.5%-8%,

[0042] TiO2 weight ratio 0.5%-3%,

[0043] ZrO2 weight ratio 0.1%-3%.

[0044] forming the glass stock solution into a vitreous body;

[0045] The glass body is heat treated at 500°C-650°C for 0.5h-10h for nucleation, and after nucleation, heat treated at 650°C-800°C for 0.5h-10h for crystallization to obtain glass-ceramics;

[0046] Cutting and grinding the glass-ceramics to obtain glass-ceramics sheets;

[0047] The glass-ceramic sheet is subjected to a strengthening treatment of chemical ion exchange.

[0048] In the embodiment of the present application, the strengthening treatment includes two ion exchanges; the first ion exchange: the molten salt composition is 0mol%-50mol% KNO3, 50mol%-100mol% NaNO3, 0mol%-5mol% LiNO3, and the molten salt temperature is 400℃-480℃; the second ion exchange: the molten salt composition is KNO3 and LiNO3 with a weight of 0%-5% of the weight of KNO3, and the molten salt temperature is 350℃-420℃.

[0049] In an embodiment of the present application, the preparation method further comprises, before the strengthening treatment, performing a hot bending treatment on the sheet of microcrystalline glass at a temperature of 650-800° C. and a molding pressure of 0.3 MPa-0.8 MPa.

[0050] A fourth aspect of the embodiments of the present application provides a method for repairing scratches on the microcrystalline glass cover plate according to the first aspect of the present application, comprising:

[0051] Polishing two opposite surfaces of the microcrystalline glass cover plate;

[0052] The polished microcrystalline glass cover plate is subjected to ion exchange treatment, and the process and parameters of the ion exchange treatment are as follows:

[0053] The molten salt composition is KNO3 and LiNO3 with a weight of 0%-5% of KNO3, the molten salt temperature is 350℃-420℃, and the ion exchange time is 0.5h-2h; or,

[0054] The composition of the molten salt is 0mol%-50mol% KNO3, 50mol%-100mol% NaNO3, 0mol%-3mol% LiNO3, the molten salt temperature is 400°C-480°C, and the ion exchange time is 0.5h-2h.

[0055] The repair method significantly improves the processing yield of the microcrystalline glass cover plate by means of a strengthening scheme of regrinding and then ion exchange.

[0056] In the implementation manner of the present application, the two opposite surfaces of the glass cover plate are respectively a concave surface and a convex surface, and a polishing disk made of sponge material is used. The polishing time of the concave surface is 900s-2500s, and the polishing time of the convex surface is 500s-1500s.

[0057] A fifth aspect of the embodiment of the present application provides a method for improving the anti-fingerprint properties of the microcrystalline glass cover plate described in the first aspect of the present application, comprising:

[0058] The microcrystalline glass cover plate is cleaned with an alkaline solution, wherein the pH value of the alkaline solution is less than 12, and after cleaning, the surface roughness Ra of the microcrystalline glass cover plate is less than 1.5 nm;

[0059] An anti-fingerprint film is coated on the microcrystalline glass cover plate by vacuum coating.

[0060] By controlling the cleaning process during the processing, the anti-fingerprint coating can meet the requirements of a water drop angle greater than 105° after 2500 times of rubber friction and a water drop angle greater than 102° after 2500 times of steel wool friction. Generally speaking, it is difficult for microcrystalline glass to achieve this level using conventional coating processes.

[0061] In the implementation manner of the present application, after the cleaning, the change in the b value of the microcrystalline glass cover plate before and after cleaning is less than 0.3. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is the Raman spectrum of the glass-ceramic sheet before and after hot bending.

[0063] Figure 2 It is a light transmittance graph of microcrystalline glass sheet and microcrystalline glass cover.

[0064] Figure 3 This is the haze distribution diagram of the glass-ceramic cover.

[0065] Figure 4 This is the b-value distribution diagram of the glass-ceramic cover.

[0066] Figure 5 It is a distribution diagram of the single-body drop ball breakage capacity of the microcrystalline glass cover.

[0067] Figure 6It is the probability distribution diagram of the four-bar bending strength B10 of the glass-ceramic cover.

[0068] Figure 7 This is the height distribution diagram of the breakage of a 180g mobile phone equipped with a microcrystalline glass cover.

[0069] Figure 8 This is the B20 probability distribution diagram of the breakage height of a 180g mobile phone equipped with a microcrystalline glass cover.

[0070] Fig. 9 This is an atomic force microscope image of the glass-ceramic cover.

[0071] Fig.10 It is a schematic flow chart of a method for preparing a microcrystalline glass cover plate according to an embodiment of the present application.

[0072] Fig.11 It is a schematic diagram of an electronic device according to an embodiment of the present application.

[0073] Main component symbols

[0074] Electronic devices 100

[0075] Screen display cover 10

[0076] Housing 30 DETAILED DESCRIPTION

[0077] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0078] Unless otherwise specified, the data range values ​​recorded in this application should include the end values.

[0079] As the back cover / shell of various electronic devices such as mobile phones, transparent glass cover plates have better appearance, better touch, stronger decorativeness, and higher sense of technology. However, glass is a brittle material and is prone to cracking when used as the back cover / shell of electronic devices.

[0080] The microcrystalline glass cover plate of the embodiment of the present application can be used as the back cover / shell or transparent screen cover plate of various electronic devices such as mobile phones. The microcrystalline glass cover plate has high strength and excellent drop resistance. The drop height of the whole device on sandpaper and marble is ≥1.5m. At the same time, the transparency and optical performance meet the screen use requirements of electronic devices such as mobile phones.

[0081] The formula of the microcrystalline glass cover plate in the embodiment of the present application is:

[0082] SiO2 weight ratio 65%-85%,

[0083] Al2O3 weight ratio 5%-12%,

[0084] Na2O weight ratio 0.5-6%,

[0085] Li2O weight ratio 4%-9%,

[0086] P2O5 weight ratio 0.05%-3%,

[0087] K2O weight ratio 0.5%-3%,

[0088] MgO weight ratio 0.5%-8%,

[0089] TiO2 weight ratio 0.5%-3%,

[0090] ZrO2 weight ratio 0.1%-3%.

[0091] The microcrystalline glass cover plate is made from the raw materials in the above ratio.

[0092] The microcrystalline glass cover plate is obtained by strengthening the microcrystalline glass sheet made of the raw materials in the above-mentioned ratio through chemical ion exchange. Compared with the conventional glass strengthening treatment, LiNO3 is added to the molten salt used in the strengthening treatment described in the present application, so that the strengthening treatment enhances the surface stress of the microcrystalline glass cover plate, improves the strength, and ensures the stability of the surface state. After the strengthening treatment, the surface layer of the microcrystalline glass sheet with a certain thickness (depth) is transformed to form a strengthening layer, the thickness of the strengthening layer is greater than or equal to 90 microns, the surface compressive stress of the strengthening layer is ≥160MPa, and the compressive stress at a depth of 50 microns from the outer surface is ≥65MPa.

[0093] The reason for adding LiNO3 is that the difference between microcrystalline glass and conventional glass is that microcrystalline glass contains a certain proportion of crystal phase. This characteristic makes microcrystalline glass, in addition to ion exchange in the glass phase, also participate in some ions in the surface crystal phase during chemical strengthening, thereby destroying the surface crystal phase and forming loose cavities on the surface. The exchanged Na ions and K ions are enriched in them. Under high temperature and high humidity environment, these ions and water vapor form white Na salts and K salts, which adhere to the glass surface and affect the cleanliness and display effect of the material. On the one hand, adding LiNO3 can inhibit the damage to the surface crystals during the strengthening process; on the other hand, it can reduce the Na ions and K ions enriched on the surface, so that the material can maintain the stability of the surface performance under high temperature and high humidity environment. The microcrystalline glass cover plate includes glass phase, quartz (SiO2) crystals, lithium disilicate (Li2Si2O5) crystals and petalite (Li[ALSi4O 10]) crystals. The glass phase refers to an amorphous substance formed after a series of physical and chemical reactions between the constituent substances and impurities during high-temperature sintering. Its main function is to bond the dispersed crystal phases together. In the microcrystalline glass cover plate, the volume of the glass phase accounts for 15%-70%, the volume of the quartz crystal accounts for 10%-55%, the volume of the lithium disilicate crystal accounts for 10%-40%, and the volume of the petalite crystal accounts for 10%-40%. The crystal size of the quartz crystal, the lithium disilicate crystal, and the petalite crystal is less than 80nm, preferably less than 50nm.

[0094] In some embodiments, the microcrystalline glass cover plate is obtained by subjecting a microcrystalline glass sheet to heat bending and chemical ion exchange strengthening treatment. That is, heat bending can be performed selectively or not. When the microcrystalline glass sheet is subjected to heat bending treatment, the formation of lithium disilicate crystals and petalite crystals will be promoted, and the number of lithium disilicate crystals and petalite crystals will increase, resulting in optimization of optical properties and improvement of strength. The main formation mechanism is that during the heat bending process, accompanied by the breaking of Si-O non-bridging oxygen bonds, lithium disilicate crystals and petalite crystals are formed by combining with Li, Al, etc.

[0095] The appearance of the microcrystalline glass cover plate includes but is not limited to a two-dimensional flat plate structure (2D), a two-dimensional flat plate structure with a certain curvature (2.5D) and a three-dimensional structure with a bend (3D). The hot bending process can be selectively performed, and for a 2D\2.5D microcrystalline glass cover plate, the hot bending process may not be performed.

[0096] See also Figure 1 , Raman spectra of glass-ceramics sheet and glass-ceramics sheet after hot bending at 750℃; the horizontal axis is 950-1050cm -1 Corresponding to Si-O non-bridging oxygen bond; horizontal coordinate 400-700cm -1 Indicates bridging oxygen. Figure 1 It can be seen that the horizontal coordinate of the microcrystalline glass sheet after hot bending is 950-1050cm -1 The peak intensity at is significantly decreased, indicating that the Si-O non-bridging oxygen bond is broken and reduced.

[0097] Combined with reference Figure 2 , the average transmittance of the microcrystalline glass sheet to light within the wavelength range of 450nm-1000nm is ≥85%; the average transmittance of the microcrystalline glass cover plate to light within the wavelength range of 450nm-1000nm is ≥88% after the microcrystalline glass sheet is hot-bent and strengthened. This shows that hot-bending and strengthening can significantly improve the light transmittance of glass.

[0098] The haze of the microcrystalline glass sheet is 1.0%-1.35%, and the color difference b value is 1.5≤|b|≤2.8. The haze of the microcrystalline glass cover plate is ≤0.2%, preferably ≤0.15%. The haze of the microcrystalline glass cover plate obtained by hot bending (optional) and strengthening the microcrystalline glass sheet is ≤0.2%, such as Figure 3 As shown, Figure 3 Each point represents a test data, and the ordinate represents the haze value. The color difference b value of the microcrystalline glass cover plate satisfies |b|≤1.2, preferably |b|≤0.8. Figure 4 As shown, the color difference b value |b|≤1.2, where Figure 4 Each point in the graph represents a test data, and the ordinate represents the color difference value b.

[0099] like Figure 5 As shown, the single drop ball energy of the microcrystalline glass cover plate is greater than 0.2 J. The single drop ball energy test is to place the test sample on the test table, and drop a steel ball of a specified weight freely on the sample from a specified drop height to impact the sample until the sample is broken, and calculate the impact energy value according to the drop height and the weight of the steel ball.

[0100] like Figure 6 As shown, the four-bar bending strength (Weibull distribution B10) of the microcrystalline glass cover is greater than 550Mpa, and the average value is greater than 800Mpa. The four-bar bending strength is a conventional test in the field of mobile phones. The specific test method is: the two support rods below support the opposite ends of the sample, and the two cylindrical pressure rods above press from the middle position of the sample from top to bottom. The force values ​​and displacements when the test sample breaks are converted to obtain the bending strength.

[0101] The microcrystalline glass cover plate is assembled on the whole machine. The weight of the whole machine including the microcrystalline glass cover plate is 180g. When dropped on sandpaper and marble, the drop height is more than 1.5m. Figure 7 As shown. Figure 8 As shown, the drop height (Weibull distribution B20) is greater than 1.65m.

[0102] See also Fig. 9 , the atomic force microscope image of the microcrystalline glass cover, from Fig. 9 It can be seen that the particle size of the microcrystalline glass cover plate is about 50nm and the surface roughness is about 1.5nm.

[0103] Combined with reference Fig.10 The method for preparing the microcrystalline glass cover plate comprises the following steps:

[0104] (1) The following raw material formula is used to melt and prepare glass stock solution at a temperature of 1300° C. to 1700° C.:

[0105] SiO2 weight ratio 65%-85%,

[0106] Al2O3 weight ratio 5%-12%,

[0107] Na2O weight ratio 0.5-6%,

[0108] Li2O weight ratio 4%-9%,

[0109] P2O5 weight ratio 0.05%-3%,

[0110] K2O weight ratio 0.5%-3%,

[0111] MgO weight ratio 0.5%-8%,

[0112] TiO2 weight ratio 0.5%-3%,

[0113] ZrO2 weight ratio 0.1%-3%.

[0114] (2) forming the glass stock solution into a transparent glass body;

[0115] (3) heat treating the glass body at 500° C.-600° C. for 0.5 h-10 h for nucleation, and after nucleation, heat treating at 650° C.-800° C. for 0.5 h-10 h for crystallization to obtain a microcrystalline glass sheet;

[0116] (4) performing a hot bending process on the glass-ceramics sheet;

[0117] (5) The microcrystalline glass sheet after hot bending is strengthened by chemical ion exchange process.

[0118] The step (2) of forming the glass body from the glass stock solution is specifically: forming the glass body by one of the following methods: rolling, melt casting, float, overflow, and sintering, and then cooling the glass body to room temperature at a uniform rate, and the cooling process is called rough annealing. Before forming the glass body, it also includes the step of removing bubbles from the glass stock solution.

[0119] like Fig.10As shown, the preparation method further includes: before the step (4) of hot bending and forming the microcrystalline glass sheet, the microcrystalline glass sheet is cut, polished, and computerized numerical control (CNC) processed. Cutting can be performed by cold processing using a CNC machine tool. For example, assuming that a microcrystalline glass product with a thickness of d is ultimately to be obtained, the thickness of the cut microcrystalline glass sheet should be 0.1-0.25 mm greater than the thickness d. Because the glass needs to be polished and other treatments after cutting, the thickness may be reduced. Usually, the thickness of the glass cover of a mobile phone is generally 0.3 mm-1.2 mm. The thin slice of the microcrystalline glass sheet obtained after cutting needs to be polished to make the surface flat and smooth. Polishing leather, brush, sponge polishing disc, etc. can be used with polishing powder for coarse grinding and fine grinding.

[0120] It can be understood that the step (4) of hot bending treatment can also be omitted. The hot bending treatment of the microcrystalline glass sheet is selectively performed. The step (4) of hot bending treatment of the microcrystalline glass sheet is specifically: hot bending at a temperature of 650°C-800°C, and the molding pressure is 0.3MPa-0.8MPa. The purpose of hot bending is to obtain a glass cover plate of the desired 3D shape. The step (5) of strengthening the microcrystalline glass sheet includes two ion exchange strengthenings. The strengthening treatment is carried out in a strengthening furnace, and the strengthening furnace is provided with a molten alkali metal salt (molten salt, also called strengthening furnace water). The microcrystalline glass is immersed in the molten salt for ion exchange and then cooled. The first ion exchange: the molten salt composition is 0mol%-50mol% KNO3, 50mol%-100mol% NaNO3, 0mol%-5mol% LiNO3, the molten salt temperature is 400°C-480°C, and the ion exchange time is 6h-15h. The second ion exchange: the molten salt composition is KNO3 and LiNO3 with a weight of 0.05%-5% of the weight of KNO3, the molten salt temperature is 350℃-420℃, and the ion exchange time is 0.5h-2h. The principle of chemical ion exchange is to form a compressive stress strengthening layer on the glass surface by exchanging alkali metal ions with larger radius (K ions, Na ions) and alkali metal ions with smaller radius (Na ions, Li ions) in the strengthening furnace water. The first ion exchange mainly replaces the lithium ions in the microcrystalline glass sheet with sodium ions in the molten salt, and the second ion exchange mainly replaces the sodium ions in the microcrystalline glass sheet with potassium ions in the molten salt. The stress strengthening layer formed on the surface of the microcrystalline glass after the above two chemical ion exchanges can effectively improve the drop resistance of the microcrystalline glass.

[0121] like Fig.10As shown, the microcrystalline glass obtained by the strengthening treatment can also be subjected to surface decoration treatment, for example, surface decoration treatment of the microcrystalline glass is carried out by silk screen printing, pad printing, coating or film bonding process, so as to obtain the microcrystalline glass cover plate with the final effect.

[0122] The microcrystalline glass sheets are subjected to hot bending and chemical ion exchange strengthening treatments. The strengthening process includes two ion exchanges. The LiNO3 component is added to the strengthening furnace water to enhance the surface stress and improve the strength while ensuring the stability of the surface state.

[0123] When the microcrystalline glass cover is formed by high-temperature 3D hot bending, the lithium disilicate crystals and petalite crystals in the microcrystalline glass sheet increase, which optimizes the optical performance and improves the strength, thereby obtaining a microcrystalline glass cover with high strength, excellent drop resistance, and optical performance that meets the requirements of display screen use. The microcrystalline glass sheet mainly includes quartz crystals, lithium disilicate crystals and petalite crystals; when the microcrystalline glass sheet is hot-bent, it will promote the formation of lithium disilicate crystals and petalite crystals. It can be seen from the raman spectrum test results before and after hot bending that during the hot bending process, accompanied by the breaking of Si-O non-bridging oxygen bonds, silicon oxygen combines with Li, Al, etc. to form lithium disilicate crystals and petalite crystals. In the microcrystalline glass cover, the volume of the glass phase accounts for 15%-70%, the volume of the quartz crystal accounts for 10%-55%, the volume of the lithium disilicate crystal accounts for 10%-40%, and the volume of the petalite crystal accounts for 10%-40%.

[0124] The average transmittance of the microcrystalline glass sheet to light in the wavelength range of 450nm-1000nm is ≥85%; the average transmittance of the microcrystalline glass cover plate obtained by hot bending (optionally performed) and strengthening treatment to light in the wavelength range of 450nm-1000nm is ≥88%.

[0125] The haze of the microcrystalline glass sheet is 1.0%-1.35%, and the color difference b value is 1.5≤|b|≤2.8; the haze of the microcrystalline glass cover plate obtained by hot bending (optionally performed) and strengthening treatment is ≤0.2%, and the color difference b value satisfies |b|≤1.2.

[0126] See also Fig.11 The present application also provides an electronic device 100, including a transparent screen display cover plate 10 and a housing 30, wherein the screen display cover plate 10 and the housing 30 cooperate to accommodate functional modules (not shown) of the electronic device 100, such as a display touch panel, a battery, a circuit board, a chip, etc. At least one of the screen display cover plate 10 and the housing 30 is the above-mentioned microcrystalline glass cover plate. In this embodiment, the electronic device 100 is a mobile phone, but is not limited to a mobile phone, and can also be other electronic devices, such as a tablet computer, etc.

[0127] Since the above-mentioned microcrystalline glass cover has high strength and excellent drop resistance, and its transparency and optical properties meet the screen usage requirements of electronic devices such as mobile phones, the service life of the electronic device 100 can be effectively improved.

[0128] The present application also provides a method for repairing the surface scratches and other poor appearance of the above-mentioned microcrystalline glass cover plate. The method can effectively improve the processing yield of the microcrystalline glass cover plate.

[0129] The method comprises: (1) polishing two opposite surfaces of a microcrystalline glass cover plate; and (2) placing the polished microcrystalline glass cover plate into a strengthening furnace for ion exchange treatment.

[0130] The two opposite surfaces of the glass cover plate are distributed as a concave surface and a convex surface, and a sponge polishing disk is used. The polishing time of the concave surface is 900s-2500s, and the polishing time of the convex surface is 500s-1500s.

[0131] The polished microcrystalline glass cover plate is subjected to ion exchange in a strengthening furnace, the molten salt composition is KNO3 and LiNO3 with a weight of 0%-5% of KNO3, the molten salt temperature is 350°C-420°C, and the ion exchange time is 0.5h-2h.

[0132] Alternatively, the molten salt composition for ion exchange is 0mol%-50mol% KNO3, 50mol%-100mol% NaNO3, 0mol%-3mol% LiNO3, the molten salt temperature is 400℃-480℃, and the ion exchange time is 0.5h-2h.

[0133] After ion exchange strengthening treatment, the compressive stress (CS_50) of the microcrystalline glass cover plate at a depth of 50 microns from the outer surface is ≥65MPa, the strengthening depth (DOL) is ≥90μm, and the surface stress (CT) is ≥160MPa. The single-body strength four-bar bending strength B10 of the microcrystalline glass cover plate is greater than 550Mpa, and the single-body falling ball energy is greater than 0.2J.

[0134] The present application also provides an anti-fingerprint method for the above-mentioned microcrystalline glass cover plate. The method comprises: (1) cleaning the microcrystalline glass cover plate with an alkaline solution; (2) coating an anti-fingerprint film on the microcrystalline glass cover plate by vacuum coating.

[0135] The microcrystalline glass cover plate is cleaned with an alkaline solution, wherein the pH value of the alkaline solution is less than 12. After cleaning, the surface roughness Ra of the microcrystalline glass cover plate is less than 1.5 nm. Compared with before and after cleaning, the b value change of the microcrystalline glass cover plate is less than 0.3.

[0136] The anti-fingerprint film is coated on the microcrystalline glass cover plate by vacuum coating. Usually, before coating the anti-fingerprint film, a base layer is pre-formed on the microcrystalline glass cover plate. The base layer can be a SiO2 layer with a thickness of 3nm-15nm, which can be obtained by vacuum sputtering or evaporation coating. Then, a low surface energy anti-fingerprint film with a thickness of 10nm-50nm is formed on the base layer. The composition can be a chain substance such as perfluoropolyether, which is mainly obtained by evaporation coating. The vacuum degree of the coating machine is preferably 5*10 -5 torr or more. In some embodiments, the vacuum coating is divided into three operation steps: plasma treatment of the glass surface, coating of SiO2 base layer, and coating of an anti-fingerprint film layer of an organic material. The plasma treatment time is 50-300s; the speed of coating the SiO2 base layer is 0.5-2rpm, the time is 200-600s, the voltage is 2-5v, and the current is 150mA-300mA; the speed of coating the anti-fingerprint film layer is 1.0-2rpm, the time is 300-700s, the voltage is 2-5v, and the current is 150mA-300mA.

[0137] The water drop angle of the microcrystalline glass cover plate coated with the anti-fingerprint film layer is greater than 105° after 3500 times of rubber friction. As shown in Table 1 below, the water drop angle of the microcrystalline glass cover plate coated with the anti-fingerprint film layer is greater than 109° after 3500 times of rubber friction.

[0138] Table 1

[0139]

[0140] The water drop angle of the microcrystalline glass cover plate coated with the anti-fingerprint film layer is greater than 102° after 2500 times of steel wool friction. As shown in Table 2 below, the water drop angle is greater than 103°.

[0141] Table 2

[0142]

[0143] The embodiments of the present application are further described below through specific examples.

[0144] Embodiment 1

[0145] The raw materials with a mass ratio of 70% SiO2, 11% Al2O3, 1% Na2O, 8% Li2O, 3% P2O5, 1% K2O, 3% MgO, 2% TiO2, and 1% ZrO2 were melted at 1650°C and formed into blocks. Through the cutting process, the blocks were cut into sheets with a thickness of 0.7-0.9mm, and then the sheets were crystallized, heat treated at 550°C for 6h, then heated to 720°C at 30°C / h, kept warm for 5h, and finally cooled to room temperature in the furnace to obtain transparent microcrystalline glass.

[0146] Through CNC machining and polishing, the crystallized sheet is polished to a transparent sheet of 0.55-0.75mm. Then, under the conditions of hot bending at 730℃ and 0.65MPa, the flat microcrystalline glass is formed into a 3D curved microcrystalline glass.

[0147] The formed 3D microcrystalline glass was strengthened by ion exchange, and the strengthening conditions were as follows: for the first ion exchange, the molten salt composition was 7.8mol% KNO3, 92mol% NaNO3, 0.2mol% LiNO3, the molten salt temperature was 450°C, and the ion exchange time was 11h; for the second ion exchange, the molten salt composition was 99.8wt% KNO3, 0.2wt% LiNO3, the molten salt temperature was 390°C, and the ion exchange time was 1h.

[0148] Finally, the processed 3D microcrystalline glass is decorated with pad printing ink and anti-fingerprint coating to obtain a 3D curved microcrystalline glass cover.

[0149] The prepared curved microcrystalline glass cover has an average light transmittance of ≥88%, preferably ≥91.5%, |b value|≤1.2, preferably |b value|≤0.8, and a haze of ≤0.2%, preferably ≤0.15% within a wavelength range of 450nm-1000nm.

[0150] The prepared microcrystalline glass cover plate was assembled on a 180g mobile phone and could survive a 1.5m marble drop and a 180-grit sandpaper drop.

[0151] Embodiment 2

[0152] The raw materials with a mass ratio of 68% SiO2, 10% Al2O3, 3% Na2O, 7% Li2O, 5% P2O5, 1% K2O, 3% MgO, 2% TiO2, and 1% ZrO2 were melted at 1650°C and formed into blocks. Through the cutting process, the blocks were cut into sheets with a thickness of 0.7-0.9mm, and then the sheets were crystallized, heat treated at 550°C for 7.5h, then heated to 720°C at 40°C / h, kept warm for 6h, and finally cooled to room temperature in the furnace to obtain transparent microcrystalline glass.

[0153] Through CNC machining and polishing, the crystallized sheet is polished to a transparent sheet of 0.55-0.75mm. Then, under the hot bending conditions of 720℃ and 0.75MPa, the flat microcrystalline glass is formed into a 3D curved microcrystalline glass.

[0154] The formed 3D microcrystalline glass was strengthened by ion exchange, and the strengthening conditions were as follows: for the first ion exchange, the molten salt composition was 9.8mol% KNO3, 90mol% NaNO3, 0.2mol% LiNO3, the molten salt temperature was 450°C, and the ion exchange time was 10h; for the second ion exchange, the molten salt composition was 99.8wt% KNO3, 0.2wt% LiNO3, the molten salt temperature was 380°C, and the ion exchange time was 1.5h.

[0155] Finally, the processed curved microcrystalline glass is decorated with pad printing ink and anti-fingerprint coating to obtain a 3D curved microcrystalline glass cover.

[0156] During the processing, long-term strong alkaline treatment should be avoided. When using flat plate and ultrasonic tank cleaning, the pH of the cleaning solution should be less than 12, the temperature should be less than 65℃, and the single cleaning time should be less than 60min.

[0157] Before anti-fingerprint coating, the cleaning process is controlled to ensure that the b value change before and after cleaning is less than 0.3 and the surface roughness Ra is less than 1.5nm.

[0158] The prepared curved microcrystalline glass cover can achieve a water drop angle greater than 105° after 2500 rubber frictions, and a water drop angle greater than 100° after 2500 steel wool frictions.

[0159] The prepared microcrystalline glass cover plate was assembled on a 180g mobile phone and could survive a 1.5m marble drop and a 180-grit sandpaper drop.

[0160] Embodiment 3

[0161] The raw materials with a mass ratio of 69% SiO2, 10% Al2O3, 2% Na2O, 7% Li2O, 3% P2O5, 1% K2O, 5% MgO, 2% TiO2, and 1% ZrO2 were melted at 1650°C and formed into blocks. Through the cutting process, the blocks were cut into sheets with a thickness of 0.7-0.9mm, and then the sheets were crystallized, heat treated at 580°C for 6h, then heated to 720°C at 30°C / h, kept warm for 6h, and finally cooled to room temperature in the furnace to obtain transparent microcrystalline glass.

[0162] Through CNC machining and polishing, the crystallized sheet is polished to a transparent sheet of 0.55-0.75mm. Then, under the conditions of hot bending at 730℃ and 0.65MPa, the flat microcrystalline glass is formed into a 3D curved microcrystalline glass.

[0163] The formed 3D glass ceramic cover plate was strengthened by ion exchange, and the strengthening conditions were as follows: for the first ion exchange, the molten salt composition was 21.8mol% KNO3, 78mol% NaNO3, 0.2mol% LiNO3, the molten salt temperature was 450°C, and the ion exchange time was 11h; for the second ion exchange, the molten salt composition was 99.5wt% KNO3, 0.5wt% LiNO3, the molten salt temperature was 390°C, and the ion exchange time was 45min.

[0164] Finally, the processed curved microcrystalline glass is decorated with pad printing ink and anti-fingerprint coating to obtain a 3D curved microcrystalline glass cover.

[0165] If the strengthened glass cover has surface scratches or defects in the pad printing ink process, the defective samples can be reworked. The rework process is: the defective products are re-grinded, the time is 1200s for concave surface grinding and 700s for convex surface grinding. The samples after grinding are strengthened in a strengthening furnace, the molten salt composition is 99.8wt% KNO3, 0.2wt% LiNO3, the molten salt temperature is 390℃, and the ion exchange time is 1h.

[0166] The prepared microcrystalline glass cover can repair scratches and ink defects after strengthening rework. After rework, the CS_50 of the microcrystalline glass sample is ≥80MPa, DOL ≥100μm, and CT ≤125MPa.

[0167] The prepared microcrystalline glass cover plate was assembled on a 180g mobile phone and could survive a 1.5m marble drop and a 180-grit sandpaper floor drop.

[0168] It should be noted that the above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application; in the absence of conflict, the implementation methods of the present application and the features in the implementation methods can be combined with each other. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A glass-ceramic cover plate, characterized in that: The microcrystalline glass cover plate is obtained by strengthening the microcrystalline glass sheet through chemical ion exchange, and the molten salt used in the strengthening treatment contains LiNO3; The microcrystalline glass cover plate comprises: Glass phase, accounting for 15%-70% by volume; Quartz crystal, accounting for 10%-55% by volume; Lithium disilicate crystals, accounting for 10%-40% by volume; The volume proportion of petalite crystals is 10%-40%, and the four-bar bending strength B10 of the microcrystalline glass cover plate is greater than 550MPa, and the average value is greater than 800MPa; The color difference b value of the microcrystalline glass cover plate satisfies |b|≤1.2, and the haze of the microcrystalline glass cover plate is ≤0.2%.

2. The glass-ceramic cover plate according to claim 1, characterized in that: The formula of the microcrystalline glass cover plate is: SiO2 weight ratio 65%-85%, Al2O3 weight ratio 5%-12%, Na2O weight ratio 0.5-6%, Li2O weight ratio 4%-9%, P2O5 weight ratio 0.05%-3%, K2O weight ratio 0.5%-3%, MgO weight ratio 0.5%-8%, TiO2 weight ratio 0.5%-3%, ZrO2 weight ratio 0.1%-3%.

3. The glass-ceramic cover plate according to claim 1, characterized in that: The microcrystalline glass cover plate is obtained by subjecting the microcrystalline glass sheet to heat bending and strengthening treatment by chemical ion exchange.

4. The glass-ceramic cover plate according to claim 1, characterized in that: The crystal sizes of the quartz crystal, the lithium disilicate crystal and the petalite crystal are all less than 80 nm.

5. The glass-ceramic cover plate according to any one of claims 1 to 4, characterized in that: The average transmittance of the microcrystalline glass cover plate to light in the wavelength range of 450nm-1000nm is greater than or equal to 88%.

6. The glass-ceramic cover plate according to any one of claims 1 to 4, characterized in that: The depth of the strengthening layer of the microcrystalline glass cover plate is greater than or equal to 90 microns.

7. The glass-ceramic cover plate according to any one of claims 1 to 4, characterized in that: The surface compressive stress of the strengthening layer of the microcrystalline glass cover plate is ≥160 MPa, and the compressive stress of the strengthening layer at a depth of 50 microns from the outer surface is ≥65 MPa.

8. The glass-ceramic cover plate according to any one of claims 1 to 4, characterized in that: The single-body falling ball energy that the microcrystalline glass cover plate can withstand is greater than 0.2J.

9. The glass-ceramic cover plate according to any one of claims 1 to 4, characterized in that: The microcrystalline glass cover plate is assembled on a whole machine including the microcrystalline glass cover plate and weighing 180 g, and has sandpaper drop and marble drop strength of the whole machine at a height of more than 1.5 m.

10. The glass-ceramic cover plate according to any one of claims 1 to 4, characterized in that: The microcrystalline glass cover plate also includes an anti-fingerprint film, and the water drop angle of the microcrystalline glass cover plate is greater than 105° after being rubbed with rubber for 3500 times.

11. An electronic device, comprising a transparent screen display cover and a housing, characterized in that: At least one of the screen display cover plate and the shell is the microcrystalline glass cover plate as described in any one of claims 1 to 10.

12. A method for repairing a scratched glass-ceramic cover plate according to any one of claims 1 to 10, characterized in that: include: Polishing two opposite surfaces of the microcrystalline glass cover plate; The polished microcrystalline glass cover plate is subjected to ion exchange treatment, and the process and parameters of the ion exchange treatment are as follows: The molten salt composition is KNO3 and LiNO3 with a weight of 0%-5% of KNO3, wherein the content of LiNO3 does not include 0%, the molten salt temperature is 350℃-420℃, and the ion exchange time is 0.5-2h; or, The composition of the molten salt is 0mol%-50mol% of KNO3, 50mol%-100mol% of NaNO3, and 0mol%-3mol% of LiNO3, wherein the content of LiNO3 does not include 0mol%, the molten salt temperature is 400°C-480°C, and the ion exchange time is 0.5-2h.

13. The repair method according to claim 12, characterized in that: The two opposite surfaces of the microcrystalline glass cover plate are respectively a concave surface and a convex surface, and a sponge polishing disk is used. The polishing time of the concave surface is 900s-2500s, and the polishing time of the convex surface is 500s-1500s.

14. An anti-fingerprint method for a glass-ceramic cover plate according to any one of claims 1 to 9, characterized in that: include: The microcrystalline glass cover plate is cleaned with an alkaline solution, wherein the pH value of the alkaline solution is less than 12, and after cleaning, the surface roughness Ra of the microcrystalline glass cover plate is less than 1.5 nm; The anti-fingerprint film is coated on the microcrystalline glass cover plate by vacuum coating, so that the water drop angle of the microcrystalline glass cover plate coated with the anti-fingerprint film is greater than 105° after being rubbed with rubber for 3500 times.

15. The anti-fingerprint method according to claim 14, characterized in that: Before and after the cleaning, the b value of the microcrystalline glass cover plate changes by less than 0.3.

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