A tempered glass, a glass tempering method and an electronic equipment housing

Abstract

The present application provides a tempered glass, a glass tempering method and an electronic device housing, wherein the tempered glass has a surface compressive stress layer on both opposite sides, and a third stress layer is sandwiched between the two surface compressive stress layers, wherein the third stress layer includes a compressive stress region and a plurality of tensile stress regions spaced apart in the compressive stress region, wherein the plurality of tensile stress regions are arranged in a direction perpendicular to the thickness of the tempered glass, and each tensile stress region is surrounded by a compressive stress region; the sum of the depth of the two surface compressive stress layers and the depth of the compressive stress region between two adjacent tensile stress regions is equal to the thickness of the tempered glass. The distribution depth of the compressive stress in the tempered glass can be equal to its thickness, and the internal tensile stress is surrounded by the compressive stress, so that the crack propagation in the tempered glass is fully hindered, and the mechanical properties are relatively good.

Description

Technical Field

[0001] The present application relates to the technical field of tempered glass, and in particular to tempered glass, a glass tempering method and an electronic equipment housing. Background Art

[0002] Glass is widely used as a cover plate in the field of electronic products. As electronic products continue to develop in the direction of being lighter and thinner, the requirements for the mechanical properties of glass cover plates are becoming more and more stringent. Among them, chemical strengthening (i.e., ion exchange) can be used to improve the mechanical properties of glass. It uses large-radius ions in molten salt to replace small-radius ions on the surface of the glass, forming a compressive stress layer of a certain thickness on the surface of the glass. This compressive stress layer can significantly hinder the expansion of cracks in the glass, thereby improving the strength of the strengthened glass.

[0003] However, the depth of stress layer (DOL) of strengthened glass reported in the industry is relatively shallow, generally not exceeding half of the glass thickness, and its effect on hindering the expansion of microcracks is limited, resulting in the mechanical strength of the glass being mainly affected by surface and internal microcracks. Therefore, it is necessary to provide a strengthening method that can effectively hinder crack expansion and increase the intrinsic strength of glass, so as to improve the mechanical properties of strengthened glass. Summary of the invention

[0004] In view of this, the present application provides a glass strengthening method and strengthened glass, which form a periodic circumferential compressive stress distribution inside the glass and a uniform and dense surface compressive stress layer on the surface through a specific two-step chemical strengthening process, so as to achieve a multi-layer barrier effect on the diffusion of microcracks on the surface and inside the glass, slow down or even eliminate the influence of a single crack on the overall strength of the glass, and improve the mechanical properties of the glass, such as the fracture threshold, bending strength, and impact resistance.

[0005] In a first aspect, the present application provides a tempered glass, the tempered glass comprising a first surface and a second surface arranged opposite to each other, the first surface having a first surface compressive stress layer, the second surface having a second surface compressive stress layer, the tempered glass further comprising a third stress layer sandwiched between the first surface compressive stress layer and the second surface compressive stress layer, wherein the third stress layer comprises a compressive stress region and a plurality of tensile stress regions spaced apart in the compressive stress region, the plurality of tensile stress regions are arranged in a direction perpendicular to the thickness of the tempered glass, and each of the tensile stress regions is surrounded by the compressive stress regions; the sum of the maximum depth of the compressive stress region and the depths of the first surface compressive stress layer and the second surface compressive stress layer is equal to the thickness of the tempered glass.

[0006] There is a surface compressive stress layer with a relatively high stress value on the surface of the tempered glass, and compressive stress is distributed throughout the thickness direction of the tempered glass between the tensile stress regions, which makes the stress depth of the tempered glass very deep. In addition, there is a surrounding compressive stress distribution in which the compressive stress region surrounds the tensile stress region inside the tempered glass, so that the crack propagation in the tempered glass is fully hindered, thereby making its mechanical properties better.

[0007] A second aspect of the present application provides a glass strengthening method, comprising the following steps:

[0008] A plurality of shielding layers are formed on a first surface and a second surface of the glass substrate, respectively, and are spaced apart from each other; wherein the shielding layers on the first surface correspond to the shielding layers on the second surface one by one;

[0009] Performing a first chemical strengthening on the glass substrate with the shielding layer to form an original compressive stress layer on the surface of the glass substrate covered by the shielding layer and on the surface and inside of the glass substrate not covered by the shielding layer, and forming a plurality of tensile stress regions inside the glass covered by the shielding layer, wherein the tensile stress regions are surrounded by the original compressive stress layer, and the depth of the original compressive stress layer not covered by the shielding layer is equal to the thickness of the glass substrate;

[0010] removing the shielding layer;

[0011] The glass substrate after the shielding layer is removed is subjected to a second chemical strengthening to obtain strengthened glass.

[0012] The glass strengthening method provided in the embodiment of the present application has a simple process, convenient operation, and high controllability. The strengthened glass obtained by the above-mentioned strengthening method has a surface compressive stress layer on its surface, and a compressive stress distribution surrounding the tensile stress area inside. The overall stress depth of the strengthened glass is deep and equal to the thickness of the strengthened glass, and the mechanical properties are greatly improved.

[0013] A third aspect of the present application provides an electronic device housing, which includes the tempered glass as described in the first aspect of the present application, or includes tempered glass produced by the glass method described in the second aspect of the present application.

[0014] The electronic device housing containing the above-mentioned tempered glass can meet the requirements of electronic devices for being thinner and lighter, and has good mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1A It is a schematic diagram of the cross-sectional structure of a glass substrate with a shielding layer.

[0016] Figure 1B A top view of a glass substrate with a shielding layer.

[0017] Figure 2A Schematic diagram of ion exchange after the first chemical strengthening of the glass substrate.

[0018] Figure 2B Schematic diagram of the structure of the glass substrate after the first chemical strengthening.

[0019] Figure 3 Schematic diagram of ion exchange after the glass substrate is chemically strengthened for the second time.

[0020] Figure 4 This is a schematic diagram of the structure of the tempered glass provided in an embodiment of the present application.

[0021] Figure 5 This is a schematic diagram of the structure of the tempered glass prepared in Comparative Example 1.

[0022] Explanation of reference numerals: 10 - glass substrate, 20 - shielding layer, 30 - original compressive stress layer, 31 ' - first surface compressive stress layer, 31 " - second surface compressive stress layer, 32 - compressive stress region in the third stress layer, 40 - tensile stress region in the third stress layer. DETAILED DESCRIPTION

[0023] Described below are exemplary implementations of the embodiments of the present invention. It should be noted that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the embodiments of the present invention. These improvements and modifications are also considered to be within the scope of protection of the embodiments of the present invention.

[0024] The present invention provides a glass strengthening method, comprising the following steps:

[0025] S01, see Figure 1A and Figure 1B , forming a plurality of shielding layers 20 distributed at intervals on the first surface 10a and the second surface 10b of the glass substrate 10 respectively; wherein the shielding layers on the first surface 10a correspond to the shielding layers on the second surface 10b one by one;

[0026] S02, performing a first chemical strengthening on the glass substrate 10 with the shielding layer 20, so as to form an original compressive stress layer 30 on the surface of the glass substrate 10 covered by the shielding layer 20 and on the surface and inside of the glass substrate 10 not covered by the shielding layer 20, and to form a plurality of tensile stress regions 40 inside the glass covered by the shielding layer 20, wherein the tensile stress regions 40 are surrounded by the original compressive stress layer 30, and the depth of the original compressive stress layer 30 not covered by the shielding layer 20 is equal to the thickness of the glass substrate 10 (see Figure 2A );

[0027] S03, removing the shielding layer 20;

[0028] S04, performing a second chemical strengthening on the glass substrate 10 after removing the shielding layer 20, and obtaining Figure 3 Tempered glass shown.

[0029] In step S01, the glass substrate 10 includes a first surface 10a and a second surface 10b that are arranged opposite to each other, wherein a plurality of shielding layers 20 are formed on the first surface 10a and are distributed at intervals, and the plurality of shielding layers 20 are in direct contact with the first surface 10a; and a plurality of shielding layers 20 are formed on the second surface 10b and are distributed at intervals. The first surface 10a may be the upper surface of the glass substrate 10, and the second surface 10b may be the lower surface of the glass substrate 10. For better distinction, the shielding layer on the first surface 10a may be referred to as a first shielding layer, and the shielding layer on the second surface 10b may be referred to as a second shielding layer. The first shielding layer and the second shielding layer are arranged in a one-to-one correspondence. In other words, each first shielding layer on the second surface 10b corresponds to a second shielding layer on the first surface 10a (the two completely overlap in the thickness direction of the glass substrate), or the first shielding layer and the second shielding layer are symmetrical about the glass substrate 10. In this way, with the one-to-one corresponding first shielding layer and second shielding layer, it is advantageous to form a symmetrical stress distribution on the two opposite sides of the glass substrate later.

[0030] In the embodiment of the present application, the shielding layer 20 can be formed on the surface of the glass substrate by screen printing, coating (such as spraying), plating, or exposure and development. The shielding layer 20 is made of a high temperature resistant material, such as a high temperature resistant silicone material, synthetic rubber, metal oxide, etc. Among them, the pattern shape of the shielding layer 20 (specifically refers to its projection shape on the glass substrate) includes regular shapes such as circles, ellipses, triangles, rectangles, polygons, etc., or irregular shapes. The shielding layers 20 are arranged in an orderly manner on the surface of the glass substrate. For example, a plurality of shielding layers 20 can be as follows Figure 1B The array arrangement shown is set on the surface of the glass substrate, and can also be arranged in other ways as needed. The presence of the shielding layer 20 divides the surface of the glass substrate into a shielding area and an exposed area (not covered by the shielding layer 20), and can play a role in blocking the diffusion of ions in the strengthening molten salt into the glass, for example, it can prevent ion exchange inside the glass in the shielding area.

[0031] In the embodiment of the present application, the total coverage of the plurality of shielding layers 20 on the first surface 10a or the second surface 10b of the glass substrate can be 10%-70%. The area coverage of the shielding layer in this range is helpful to achieve the chemical strengthening effect described in the following step S02. Exemplarily, the total coverage can be 15%, 20%, 25%, 30%, 40%, 50%, 60% or 65%, etc. In some embodiments, the coverage is 20%-50%.

[0032] In the embodiment of the present application, the number of shielding layers 20 on the first surface 10a or the second surface 10b is greater than or equal to 3. This is conducive to forming a periodic surrounding compressive stress distribution in which a plurality of tensile stress regions 40 are spaced apart inside the original compressive stress layer 30 .

[0033] In the present application, the glass substrate 10 used is a glass containing Li element so that two-step chemical strengthening can be performed. Exemplarily, the glass substrate can be lithium aluminum silicate glass. Optionally, the thickness of the glass substrate 11 can be 0.1 mm-5 mm. This facilitates the first chemical strengthening below to obtain an original compressive stress layer 30 with a depth equal to the thickness of the glass substrate, and the mechanical properties of the strengthened glass will not be poor due to the thickness being too thin.

[0034] In step S02 of the present application, the first chemical strengthening is generally performed by ion exchange in a molten salt containing the Na element, and the Na + →Li + The second chemical strengthening is generally carried out in a molten salt containing K element, and K + →Na + Exchange is the main method. In step S02, the molten salt used for the first chemical strengthening may include the following components in percentage by mass: 60%-100% of sodium salt and 0-40% of potassium salt. In other words, the molten salt used for the first chemical strengthening may be just sodium salt, or a mixture of sodium salt and potassium salt. Taking sodium salt as an example, it may specifically be at least one of nitrates, sulfates, chlorides, etc. of the Na element, and nitrates are generally more common. Potassium salts are similar to sodium salts. Preferably, the molten salt used for the first chemical strengthening is sodium salt. Using only sodium salt for the first chemical strengthening can make use of Na with a smaller ionic radius. + Better achieve its through-distribution in the glass not covered by the shielding layer.

[0035] With the help of the above-mentioned spaced shielding layer, a longer first chemical strengthening can be carried out to achieve Na + The through-type distribution in the glass not covered by the shielding layer 20 (i.e., the entire thickness direction of the glass not covered by the shielding layer (e.g. Figure 2A The Z direction shown, which is perpendicular to the glass surface with the shielding layer, has Na + exchanged), and at the same time, Na + It can also be exchanged into the glass substrate surface covered by the shielding layer 20 (i.e., Na + Along the direction parallel to the glass surface provided with the shielding layer (such as Figure 2A The two parts together constitute the original compressive stress layer 30. In addition, due to the presence of the shielding layer 20, the Na +It is difficult to exchange energy into the interior of the glass shielded by the shielding layer 20 , and thus this area becomes a tensile stress area 40 .

[0036] In some embodiments of the present application, when the thickness of the glass substrate is greater than 0.5 mm, the strengthening time of the first chemical strengthening can be controlled to be greater than 300 min, so that the depth of the partial original compressive stress layer 30 is equal to the thickness of the glass substrate 10. In some embodiments, the strengthening time is 300 min-600 min, for example, 360 min, 420 min, 480 min or 540 min.

[0037] In the present application, the original compressive stress layer 30 is the portion of the glass substrate where the first ion exchange occurs, and can be regarded as the sum of other portions of the glass substrate except the plurality of tensile stress regions 40. The original compressive stress layer 30 can also be understood to include two portions, such as Figure 2B As shown, a part refers to the compressive stress layer part located on the surface of the glass substrate 10 ( Figure 2B The other part refers to the compressive stress layer portion surrounding the tensile stress region 40 located inside the glass substrate ( Figure 2B denoted by reference numeral 30b).

[0038] like Figure 2A As shown, after the first chemical strengthening, a periodic distribution of compressive stress and tensile stress is formed inside the glass, wherein the tensile stress region 40 is distributed at intervals inside the original compressive stress layer 30, and the tensile stress region 40 is surrounded by the original compressive stress layer 30, which helps to fully hinder the expansion of micro cracks in the tensile stress region inside the glass, and compared with the glass substrate that has not been chemically strengthened, the existence of the original pressure layer 30 formed by ion exchange changes the surrounding environment of the cracks originally in the region, making the cracks passivated, thereby inhibiting the cracks in the region from expanding outward. At the same time, the periodic distribution of compressive / tensile stress can also increase the strength limit threshold of the glass, thereby reducing the discreteness of the glass (discreteness refers to the uneven distribution of glass strength) and improving its mechanical properties.

[0039] The original compressive stress layer 30 can be regarded as the sum of the parts of the glass substrate 10 except the tensile stress region 40. It can be understood that the original compressive stress layer 30 is irregular in shape and its depth (or thickness) is not uniform, but the depth of the original compressive stress layer 30 not covered by the shielding layer 20 is equal to the thickness of the glass substrate 10. This also shows that after the first chemical strengthening, a deeper original compressive stress layer is formed, which helps to improve the mechanical properties of the glass substrate.

[0040] Optionally, the strengthening temperature of the first chemical strengthening is 350-440° C. The strengthening temperature may specifically be 390, 400, 420 or 430° C., etc.

[0041] In some embodiments of the present application, before the first chemical strengthening, the glass substrate 10 with the shielding layer 20 can be preheated, and then the preheated glass substrate can be placed in a molten salt containing the Na element for ion exchange. Preheating can avoid the glass substrate at room temperature from being directly placed in a high-temperature strengthening solution and cracking, and reduce the surface density of the glass substrate, which helps to increase the depth of the compressive stress layer obtained by chemical strengthening and the surface compressive stress value. Among them, the glass substrate can be preheated to a temperature of 320-400°C. For example, it can be heated to 350, 360, 370, 380 or 390°C, etc.

[0042] In step S03, the shielding layer 20 can be removed by at least one of mechanical grinding technology and immersion in liquid medicine. The liquid medicine used is generally an alkaline solution, such as NaOH solution, KOH solution, etc., and the alkaline solution can also be heated (for example, 50-70° C.) to increase the removal speed of the shielding layer.

[0043] In step S04, the glass substrate with the shielding layer removed is subjected to a second chemical strengthening so that ions with a larger ion radius (such as K+) (such as Figure 3 As shown in the figure, the compressive stress on the glass surface is further increased (i.e., surface compressive stress layers 31' and 31" with higher compressive stress are formed). The interior of the glass still has the above-mentioned compressive stress distribution surrounding the tensile stress region 40, and the mechanical properties of the obtained strengthened glass are better.

[0044] Depend on Figure 3 and Figure 2A By comparison, it can be seen that the sum of the areas indicated by reference numerals 31', 31" and 32 is substantially equal to Figure 2A It is understood that the depth of the surface compressive stress layer 31' or 31" may not be equal to the depth of the original compressive stress layer 30 formed on the surface of the glass substrate 10 covered by the shielding layer 20 in S02, and of course may not be equal to Figure 2B The depth of region 30a is shown in FIG.

[0045] The molten salt used in the second chemical strengthening may include the following components in percentage by mass: 0-40% sodium salt and 60-100% potassium salt. In other words, the molten salt used in the second chemical strengthening may be potassium salt only, or a mixture of sodium salt and potassium salt. Preferably, the molten salt used in the second chemical strengthening is potassium salt.

[0046] In the implementation manner of the present application, the strengthening temperature of the second chemical strengthening can be 350-440°C, and the strengthening time can be 10-200min. Specifically, the strengthening temperature of the second chemical strengthening can be 390, 400, 420 or 430°C, etc. The strengthening time of the second chemical strengthening can be 30min, 60min, 90min, 120min, 150min, 180min, etc. The strengthening time of the second chemical strengthening in the present application is relatively short, and a surface compressive stress layer with high compressive stress and more uniform distribution can be formed in a shorter time, and in combination with the above-mentioned first chemical strengthening, the time process of the entire strengthening process can be shortened.

[0047] Similarly, the glass substrate may be preheated before the second chemical strengthening to improve the strengthening effect, wherein the glass substrate may be preheated to a temperature of 320-400° C., for example, 360, 370, 380 or 390° C.

[0048] The glass strengthening method provided in the embodiment of the present application has a simple process, convenient operation, and high controllability. The strengthened glass obtained by the strengthening method has a surface compressive stress layer on its surface and a compressive stress distribution surrounding the tensile stress area inside, so that the overall stress depth of the strengthened glass is deeper and the mechanical properties are greatly improved.

[0049] The present application also provides a strengthened glass. Figure 4 As shown, the tempered glass includes first surfaces 10a and 10b arranged opposite to each other, the first surface 10a has a first surface compressive stress layer 31', the second surface 10b has a second surface compressive stress layer 31", and a third stress layer is sandwiched between the two surface compressive stress layers, the third stress layer includes a compressive stress region 32 and a plurality of tensile stress regions 40 arranged at intervals in the compressive stress region 32, the plurality of tensile stress regions 42 are arranged along a direction perpendicular to the thickness of the tempered glass, and each tensile stress region 40 is surrounded by a compressive stress region 32; the maximum depth of the compressive stress region 32 between two adjacent tensile stress regions 40 and the sum of the depths of the first surface compressive stress layer 31' and the second surface compressive stress layer 31" is equal to the thickness T of the tempered glass. The tempered glass can be obtained by the above-mentioned strengthening method of the present application.

[0050] Specifically, the first surface compressive stress layer 31' extends from the first surface 10a to a certain depth h1 inside, and the second surface compressive stress layer 31" extends from the second surface 10b to a certain depth h2 inside. h1 and h2 can be equal or different. Figure 4Only the first surface 10a and the second surface 10b of the strengthened glass are shown as having surface compressive stress layers, but the strengthening treatment of glass is generally carried out by immersing it in molten salt at a certain temperature. It is understandable that the other surfaces of the strengthened glass also have surface compressive stress layers of a certain depth.

[0051] from Figure 4 It can be known that a plurality of tensile stress regions 40 are arranged at intervals in the compressive stress region 32, forming a surrounding compressive stress distribution. Among them, a plurality of tensile stress regions 40 are arranged at intervals along a direction parallel to the first surface 10a or the second surface 10b (i.e., perpendicular to the thickness direction of the strengthened glass). It can be understood that the compressive stress region 32 is an irregular shape and its depth is not uniform. Based on the fact that a plurality of tensile stress regions 40 are arranged at intervals in the compressive stress region 32, the compressive stress region 32 can be regarded as a hollow layer in some areas, and the hollow area is filled with tensile stress regions 40. The depth of the compressive stress region 32 located between two adjacent tensile stress regions 40 is the largest, and the sum of the depth of the compressive stress region 32 and the depth of the two surface compressive stress layers on the first surface 10a and the second surface 10b is equal to the thickness T of the strengthened glass. The sum of the thickness of the third stress layer (i.e., the maximum depth of the compressive stress region 32) and the thickness of the two surface compressive stress layers 31' is equal to the thickness T of the strengthened glass. In addition, since the surface compressive stress layer 31' is located on the surface of the tempered glass and the compressive stress region 32 is located inside the tempered glass, it can be understood that the compressive stress of the surface compressive stress layer 31' is greater than the compressive stress of the compressive stress region 32. Generally, the compressive stress of the compressive stress region 32 inside the glass is greater than or equal to 8 MPa, for example, 8 MPa-100 MPa.

[0052] Therefore, the above-mentioned surrounding compressive stress distribution inside the tempered glass, together with the existence of a surface compressive stress layer with a relatively high stress value located on the surface of the tempered glass, makes the cracks in the tempered glass passivated and the propagation of the cracks is fully hindered.

[0053] In the embodiment of the present application, the thickness T of the tempered glass can be 0.1mm-5mm. Therefore, when the tempered glass is used as the shell of an electronic device (such as a display cover, a camera protection cover, a back cover, etc.), its thickness is appropriate, which can meet the needs of thin and light electronic devices, and its mechanical properties are good. Specifically, the thickness T can be 0.2mm, 0.4mm, 0.5mm, 0.8mm, 1mm, 1.2mm, 2mm, 3mm or 4mm, etc. In some embodiments, the thickness T is 0.1mm-1.2mm. At this time, the electronic device using the tempered glass is lighter and thinner.

[0054] In an embodiment of the present application, the depth of the first surface stress layer 31' or the second surface stress layer 31" is 1-10% of the thickness T of the strengthened glass. At this time, the compressive stress of the surface stress layer of the strengthened glass is relatively high and the compressive stress is relatively uniform. Among them, the depth h1 of the first surface stress layer 31' or the depth h2 of the second surface stress layer 31" is generally 1μm-50μm. In some embodiments, the depth h1 or h2 is 3μm-50μm. For example, it is 5μm, 10μm, 20μm, 30μm, 40μm, etc. In the present application, the surface compressive stress of the strengthened glass (that is, the compressive stress of the surface compressive stress layer 31' or 31") is greater than or equal to 500MPa.

[0055] In the embodiment of the present application, the number of the tensile stress regions 40 in the tempered glass is greater than or equal to 3. The presence of a proper number of tensile stress regions is conducive to forming a periodic surrounding compressive stress distribution inside the tempered glass. It can be understood that the number of the tensile stress regions 40 corresponds to the number of shielding layers on the first surface 10a or the second surface 10b.

[0056] In the embodiment of the present application, the bending strength of the tempered glass is greater than or equal to 800 MPa. Bending strength refers to the maximum stress that an object can withstand when it breaks under a bending load or reaches a specified bending moment. A higher bending strength reflects that the tempered glass has better toughness and is not easy to break. In some embodiments, the bending strength of the tempered glass is 950 MPa-1500 MPa. Further, the bending strength can be 950 MPa-1200 MPa.

[0057] In the embodiment of the present application, the impact energy of the tempered glass is greater than or equal to 3J. The greater impact strength reflects that the tempered glass has strong impact resistance, is not easy to break, and has good toughness. In some embodiments, the impact energy of the tempered glass is greater than or equal to 3.5J. In some embodiments, the impact energy is 3.5-6J.

[0058] An embodiment of the present application further provides an electronic device housing, which includes the tempered glass as described above in the present application, or includes tempered glass made by the glass method described above in the present application.

[0059] The electronic device using the electronic device housing can be various consumer electronic products, such as mobile phones, tablet computers, laptops, wearable devices (such as smart watches, smart bracelets), virtual reality (VR) terminal devices, augmented reality (AR), e-readers, televisions, camcorders, projectors and other electronic products.

[0060] For example, if the electronic device is a portable electronic device such as a mobile phone, a tablet computer, or a wearable product, the electronic device housing may be a display screen cover assembled on the front side of the electronic device, which covers the display module; or a back cover assembled on the back side of the electronic device. In some embodiments, when the electronic device is an electronic device with a camera function (such as a mobile phone or a digital camera), the electronic device housing may also be a camera protection cover.

[0061] The use of the above-mentioned tempered glass as the housing of electronic equipment can meet the requirements of electronic equipment to be thin and light, and has good mechanical properties.

[0062] The present application is further described below through specific embodiments.

[0063] Example 1

[0064] A glass strengthening method comprising:

[0065] (1) A lithium aluminum silicate glass with a thickness of 0.6 mm was selected, and a plurality of high temperature resistant shielding layers (with a thickness of 3 μm) were respectively printed on two opposite surfaces of the glass (such as the upper surface and the lower surface) by a screen printing process, so as to obtain a glass with partial surface shielding; wherein the shielding layers on the upper and lower surfaces of the glass corresponded to each other in one-to-one position, the shielding layers were circular with a diameter of 1 mm, and the center distance of the circles was 2 mm, the total coverage of the plurality of shielding layers on the upper and lower surfaces of the glass was 23%, and the number of shielding layers on the upper and lower surfaces of the glass substrate was 3080;

[0066] (2) preheating the glass with partially shielded surface at 350° C., and then placing it in NaNO3 molten salt at 400° C. for a first chemical strengthening for 400 min, so as to form an original compressive stress layer on the surface of the glass covered by the shielding layer and on the surface and inside of the glass not covered by the shielding layer, and forming a plurality of tensile stress regions inside the glass covered by the shielding layer, wherein the tensile stress region is surrounded by the original compressive stress layer, and the depth of the original compressive stress layer not covered by the shielding layer is 0.6 mm;

[0067] Afterwards, the strengthened glass is taken out and cleaned and dried;

[0068] (3) Soaking the first strengthened glass in a 70°C NaOH solution for 8 minutes to remove the shielding layer on the glass surface;

[0069] (4) The glass after the shielding layer is removed is preheated at 380°C, and then placed in KNO3 molten salt at 400°C for a second chemical strengthening for 130 minutes to obtain strengthened glass, which is then cleaned and dried.

[0070] The structural schematic diagram of the tempered glass obtained in Example 1 is as follows Figure 4The upper and lower surfaces of the tempered glass each have a surface compressive stress layer with a thickness of 18 μm, and the surface compressive stress of the tempered glass is 830 MPa.

[0071] Example 2

[0072] A glass strengthening method comprising:

[0073] (1) A lithium aluminum silicate glass with a thickness of 0.6 mm was selected, and a plurality of high temperature resistant shielding layers were formed at intervals at corresponding positions on the upper surface and the lower surface of the glass by screen printing to obtain glass with partial surface shielding; wherein the shielding layer was a circle with a diameter of 1 mm and a center distance of 1.5 mm, the total coverage of the plurality of shielding layers on the upper and lower surfaces of the glass was 40%, and the number of shielding layers on the upper and lower surfaces of the glass was 5350;

[0074] (2) preheating the partially shielded glass at 380° C., and then placing it in NaNO3 molten salt at 420° C. for a first chemical strengthening for 350 min to form an original compressive stress layer and multiple tensile stress regions similar to those in Example 1; after cooling, taking out the strengthened glass, washing it, and drying it;

[0075] (3) removing the shielding layer on the surface of the glass after the first strengthening by grinding;

[0076] (4) The glass after the shielding layer is removed is preheated at 380°C, and then placed in KNO3 molten salt at 420°C for a second chemical strengthening for 80 minutes to obtain strengthened glass, which is then cleaned and dried.

[0077] The structural schematic diagram of the tempered glass obtained in Example 2 is as follows Figure 4 The upper and lower surfaces of the tempered glass each have a surface compressive stress layer with a thickness of 15 μm, and the surface compressive stress of the tempered glass is 850 MPa.

[0078] Example 3

[0079] A glass strengthening method comprising:

[0080] (1) A lithium aluminum silicate glass with a thickness of 0.6 mm was selected, and a plurality of high temperature resistant shielding layers were formed at intervals at corresponding positions on the upper surface and the lower surface of the glass by screen printing process, so as to obtain glass with partial surface shielding; wherein the shielding layer was a circle with a diameter of 2 mm, the center distance of the circle was 2.4 mm, the total coverage of the plurality of shielding layers on the upper and lower surfaces of the glass was 63%, and the number of shielding layers on the upper and lower surfaces of the glass substrate was 2100;

[0081] (2) preheating the glass with partially shielded surface at 350° C., and then placing it in NaNO3 molten salt at 380° C. for the first chemical strengthening for 550 min to form an original compressive stress layer and multiple tensile stress regions similar to those in Example 1; after cooling, taking out the strengthened glass and washing and drying it;

[0082] (3) Soaking the first strengthened glass in a 70°C NaOH solution for 8 minutes to remove the shielding layer on the glass surface;

[0083] (4) The glass after the shielding layer is removed is preheated at 380°C, and then placed in KNO3 molten salt at 420°C for a second chemical strengthening for 50 minutes to obtain strengthened glass, which is then cleaned and dried.

[0084] The structural schematic diagram of the tempered glass obtained in Example 3 is as follows Figure 4 The upper and lower surfaces of the tempered glass each have a surface compressive stress layer with a thickness of 12 μm, and the surface compressive stress of the tempered glass is 900 MPa.

[0085] Example 4

[0086] A glass strengthening method, which differs from Example 3 in that:

[0087] The thickness of the lithium aluminum silicate glass is 0.5 mm; the shielding layer is a regular hexagon with a side length of 2 mm and a spacing of 1.4 mm, and the total coverage of the multiple shielding layers on the glass surface is 50%.

[0088] The structural schematic diagram of the tempered glass obtained in Example 4 is as follows Figure 4 The upper and lower surfaces of the tempered glass each have a surface compressive stress layer with a thickness of 11 μm, and the surface compressive stress of the tempered glass is 880 MPa.

[0089] Example 5

[0090] A glass strengthening method, which differs from Example 3 in that: a mixed molten salt containing 60wt% potassium nitrate and 40wt% sodium nitrate is used for the first chemical strengthening; a mixed molten salt containing 95wt% potassium nitrate and 5wt% sodium nitrate is used for the second chemical strengthening.

[0091] The structural schematic diagram of the tempered glass obtained in Example 5 is as follows Figure 4 The upper and lower surfaces of the tempered glass each have a surface compressive stress layer with a thickness of 30 μm, and the surface compressive stress of the tempered glass is 650 MPa.

[0092] In order to highlight the beneficial effects of the embodiments of the present application, the following comparative examples are provided:

[0093] Comparative Example 1

[0094] A glass strengthening method, which differs from Example 3 in that: no spaced and stepped shielding layer is formed on the glass surface, the entire glass is placed in a mixed molten salt containing 60wt% potassium nitrate and 40wt% sodium nitrate for a first chemical strengthening, the strengthening temperature is 380°C, and the time is 120 minutes; then the glass is placed in a mixed molten salt containing 95wt% potassium nitrate and 5wt% sodium nitrate for a second chemical strengthening, the strengthening temperature is 380°C, and the time is 45 minutes.

[0095] Comparative Example 2

[0096] A glass strengthening method, which is different from the third embodiment in that no shielding layer is formed on the glass surface in steps. According to the method described in the third embodiment, the glass is chemically strengthened for the first time and the second time in sequence.

[0097] Comparative Example 1 is a commonly used glass strengthening process in the art. Comparative Example 1 and Comparative Example 2 do not form a shielding layer in steps on the glass surface before strengthening. After two steps of chemical strengthening, the structure of the obtained strengthened glass is as shown in FIG. Figure 5 As shown, only a shallow surface compressive stress layer is formed on the surface of the tempered glass, and there is no compressive stress distribution inside the tempered glass, and naturally there is no surrounding stress distribution emphasized by the present application. Therefore, the mechanical properties of the tempered glass of Example 3 of the present application are better than those of Comparative Examples 1 and 2.

[0098] In order to support the beneficial effects of the embodiments of the present application, the tempered glasses in the above embodiments and comparative examples were subjected to bending strength tests and impact resistance tests, and the results are shown in Table 1 below.

[0099] Table 1

[0100] Flexural strength(MPa) Impact energy(J) Example 1 1030 3.8 Example 2 980 4 Example 3 1180 3.6 Example 4 1250 3.5 Example 5 960 3.5 Comparative Example 1 745 1.8 Comparative Example 2 650 1.5

[0101] It can be seen from Table 1 above that the tempered glass provided in the embodiment of the present application is significantly superior to the tempered glass of the comparative example in terms of bending strength and impact strength, which indicates that the mechanical properties of the tempered glass provided in the present application or the tempered glass obtained according to the tempering method of the present application have been significantly improved.

[0102] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application.

Claims

1. A tempered glass, characterized in that: The strengthened glass comprises a first surface and a second surface arranged opposite to each other, the first surface has a first surface compressive stress layer, the second surface has a second surface compressive stress layer, and the strengthened glass further comprises a third stress layer sandwiched between the first surface compressive stress layer and the second surface compressive stress layer, wherein the third stress layer comprises a compressive stress region and a plurality of tensile stress regions arranged at intervals in the compressive stress region, the plurality of tensile stress regions are arranged along a direction perpendicular to the thickness of the strengthened glass, and each tensile stress region is surrounded by the compressive stress region; the sum of the maximum depth of the compressive stress region and the depths of the first surface compressive stress layer and the second surface compressive stress layer is equal to the thickness of the strengthened glass; The tempered glass is prepared by the following method: forming a plurality of shielding layers distributed at intervals on a first surface and a second surface of a glass substrate that are opposite to each other, the shielding layers on the first surface corresponding to the shielding layers on the second surface one by one; performing a first chemical strengthening on the glass substrate with the shielding layers; removing the shielding layers; and performing a second chemical strengthening on the glass substrate after the shielding layers are removed.

2. The tempered glass according to claim 1, wherein: The thickness of the tempered glass is 0.1 mm-5 mm.

3. The tempered glass according to claim 1, wherein: The depth of the first surface stress layer is 1-10% of the thickness of the strengthened glass, and the depth of the second surface stress layer is 1-10% of the thickness of the strengthened glass.

4. The tempered glass according to claim 1, wherein: The surface compressive stress of the tempered glass is greater than or equal to 500 MPa.

5. The tempered glass according to claim 1, wherein: In the tempered glass, the number of the tensile stress regions is greater than or equal to 3.

6. The tempered glass according to claim 1, wherein: The compressive stress in the compressive stress region is less than the surface compressive stress of the tempered glass, and the compressive stress in the compressive stress region is greater than or equal to 8 MPa.

7. The tempered glass according to any one of claims 1 to 6, characterized in that: The bending strength of the tempered glass is greater than or equal to 800 MPa.

8. The tempered glass according to any one of claims 1 to 6, characterized in that: The impact energy of the tempered glass is greater than or equal to 3J.

9. A glass strengthening method, characterized in that: The following steps are involved: A plurality of shielding layers are formed on a first surface and a second surface of the glass substrate, respectively, and are spaced apart from each other; wherein the shielding layers on the first surface correspond to the shielding layers on the second surface one by one; Performing a first chemical strengthening on the glass substrate with the shielding layer to form an original compressive stress layer on the surface of the glass substrate covered by the shielding layer and on the surface and inside of the glass substrate not covered by the shielding layer, and forming a plurality of tensile stress regions inside the glass covered by the shielding layer, wherein the tensile stress regions are surrounded by the original compressive stress layer, and the depth of the original compressive stress layer not covered by the shielding layer is equal to the thickness of the glass substrate; removing the shielding layer; The glass substrate after the shielding layer is removed is subjected to a second chemical strengthening to obtain strengthened glass.

10. The glass strengthening method according to claim 9, characterized in that: The total coverage of the plurality of shielding layers on the first surface or the second surface is 10%-70%.

11. The glass strengthening method according to claim 9 or 10, characterized in that: On the first surface or the second surface, the number of the shielding layers is greater than or equal to 3.

12. The glass strengthening method according to claim 9, characterized in that: When the thickness of the glass substrate is greater than 0.5 mm, the strengthening time of the first chemical strengthening is greater than 300 min.

13. The glass strengthening method according to claim 9 or 12, characterized in that: The first chemical strengthening uses molten salt containing sodium elements, and the strengthening temperature is 350-440°C.

14. The glass strengthening method according to claim 9, wherein: The second chemical strengthening uses molten salt containing potassium, and the strengthening temperature is 350-440°C.

15. The glass strengthening method according to claim 9, wherein: The strengthening time of the second chemical strengthening is 10-200 minutes.

16. An electronic device housing, characterized in that: The electronic device housing comprises the tempered glass according to any one of claims 1 to 8, or comprises the tempered glass produced by the glass method according to any one of claims 9 to 15.

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