Lithium-aluminum-silicon glass, cover plate and electronic equipment

Abstract

The invention relates to the technical field of lithium-aluminum-silicon glass reinforcement, in particular to lithium-aluminum-silicon glass, a cover plate and electronic equipment, the lithium-aluminum-silicon glass comprises a pressure stress layer and a tensile stress layer, the pressure stress layer is a part from the glass surface to DOL-0, and the rest is the tensile stress layer; the stress curve meets the conditions that CT-AV is larger than or equal to 70 MPa and smaller than or equal to 120 MPa, and CT-CV is larger than or equal to 100 MPa and smaller than or equal to 140 MPa; the absolute value of the average slope of stress distribution from the stress inflection point to DOL-0 is 1.2-2.3 MPa / mu m, the absolute value of the average slope of stress distribution from the surface of the glass to the stress inflection point is 60-250 MPa / mu m, the thickness range from the surface of the glass to the stress inflection point is 0-0.01 t, and the lithium-aluminum-silicon glass strengthening process is adjusted according to the conditions, so that the CT value is stabilized in the optimal range of glass strengthening. Therefore, the strength of the strengthened glass is obviously improved, and meanwhile, the phenomenon that the glass is self-exploded or the falling performance is reduced due to excessive strengthening is avoided. The problem that the whole machine abrasive paper falling performance is low due to the fact that existing lithium aluminum silicon glass is low in ion exchange depth is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium aluminosilicate glass strengthening, specifically to a lithium aluminosilicate glass, a cover plate and an electronic device, in particular to a lithium aluminosilicate glass, a cover plate and an electronic device with excellent anti-drop performance and deep secondary strengthening Background Art With the rise of 5G technology, new display technologies are becoming thinner and lighter, with diversified application scenarios and large-screen smart touch screens. Terminals and consumers have higher requirements for the anti-destruction performance of display cover glass, such as excellent impact resistance, scratch resistance and outstanding drop resistance.

[0002] Lithium aluminum silicon secondary strengthened glass can achieve the simultaneous increase of the depth of compressive stress layer (DOL-0) and the surface compressive stress (CS) of chemically strengthened glass through chemical strengthening, making it superior to sodium aluminum silicon single strong glass in terms of whole machine drop. The central tensile stress (CT) value of chemically strengthened glass is one of the important data to characterize the degree of chemical strengthening. When CS is low, the degree of strengthening is not in place, resulting in an insignificant improvement in glass strength; when CT is too large, the glass is over-strengthened, which will cause the glass to explode, creating safety hazards and significantly reducing the drop performance of the whole machine. Therefore, the monitoring of CT value is very important. In addition, when designing the chemical strengthening process, it is necessary to optimize the internal stress distribution of the glass to improve the resistance of chemically strengthened glass to flexural breakage and sharp contact breakage. Studies have shown that chemically strengthened glass with larger DOL-0 and inflection point stress values ​​has outstanding advantages in whole machine drop. However, at present, lithium aluminum silicon secondary strong glass has low ion exchange depth and low values ​​such as inflection point stress, which directly leads to problems such as low sandpaper drop performance of the whole machine. Summary of the invention

[0003] In view of the problem in the prior art that the ion exchange depth of lithium aluminum silicate glass is low, resulting in low sandpaper drop performance of the whole machine, the present invention provides a lithium aluminum silicate glass, a cover plate and an electronic device.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a lithium aluminum silicate glass, comprising a compressive stress layer and a tensile stress layer, wherein the compressive stress layer is the portion from the glass surface to DOL-0, and the rest is a tensile stress layer; The stress curve satisfies 70MPa≤|CT-AV|≤120MPa, 100MPa≤|CT-CV|≤140MPa; wherein, |CT-AV| is the absolute value of the average tensile stress in the tensile stress layer, and |CT-CV| is the absolute value of the maximum tensile stress in the tensile stress layer; The absolute value of the average slope of the stress distribution from the stress inflection point to DOL-0 is 1.2 to 2.3 MPa / um; The absolute value of the average slope of the stress distribution from the glass surface to the stress inflection point is 60 to 250 MPa / um, and the thickness range from the glass surface to the stress inflection point is 0 to 0.01t, where t is the thickness of the lithium aluminosilicate glass.

[0005] Further, DOL-0 ≥ 0.2t, where t is the thickness of the lithium aluminosilicate glass.

[0006] Further, the compressive stress on the glass surface is 700 to 1200 Mpa, and the K 2 O concentration on the glass surface > 8 wt%.

[0007] Further, the compressive stress at the stress inflection point ≥ 180 MPa, and the Na 2 O > 11 wt% at the inflection point.

[0008] Further, the lithium aluminosilicate glass comprises the following components: 56 wt% to 59.65 of SiO 2 , 23.1 wt% to 24.65 wt% of Al 2 O 3 , 3.15 wt% to 4.2 wt% of B 2 O 3 , 2.89 wt% to 3.4 wt% of Li 2 O, 3.25 wt% to 4.61 wt% of Na 2 O, 0 wt% to 1.2 wt% of K 2 O, 0 wt% to 0.75 wt% of MgO, 0.85 wt% to 1.36 wt% of CaO, 1.4 wt% to 1.71 wt% of SrO, 0 wt% to 2.15 wt% of P 2 O 5 and 0.15 wt% to 0.21 wt% of SnO 2 .

[0009] Further, the lithium aluminosilicate glass is obtained by two-step chemical strengthening. By mass percentage, the molten salt used in the first chemical strengthening comprises 0% to 80% potassium nitrate and 20% to 100% sodium nitrate, and the molten salt used in the second chemical strengthening comprises 95% to 100% potassium nitrate and 0% to 5% sodium nitrate.

[0010] Further, during the two-step chemical strengthening process, the Na + diffusion coefficient > 220 um 2 / min, and the K + diffusion coefficient > 2 um 2 / min.

[0011] Furthermore, when the thickness of the lithium aluminum silicate glass is 0.7 mm, the drop height of 180-grit sandpaper is ≥ 1900 mm; the Vickers hardness is > 600 kgf / mm 2 ; Young's modulus>80Gpa; 4PB>800MPa; Drop ball impact strength>0.25J.

[0012] The present invention provides a cover plate, which is prepared by using the lithium aluminosilicate glass.

[0013] The present invention provides an electronic device, comprising the above-mentioned cover plate.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a lithium aluminum silicate glass, comprising a compressive stress layer and a tensile stress layer, wherein the compressive stress layer is a portion from the glass surface to DOL-0, and the rest is a tensile stress layer; a stress curve is set to satisfy 70MPa≤|CT-AV|≤120MPa, 100MPa≤|CT-CV|≤140MPa; the absolute value of the average slope of the stress distribution from the stress inflection point to DOL-0 is 1.2-2.3MPa / um, and the absolute value of the average slope of the stress distribution from the glass surface to the stress inflection point is 60-250MPa / um. Pa / um, the thickness range from the glass surface to the stress inflection point is 0~0.01t, and the lithium aluminum silicate glass strengthening process is adjusted according to the above conditions, so that the strengthened lithium aluminum silicate glass has a specific stress structure, so that the CT value is stable in the optimal range of glass strengthening, thereby significantly improving the strength of the strengthened glass while avoiding the self-explosion of the glass or the decrease in drop performance due to excessive strengthening. After testing, when the thickness of the lithium aluminum silicate glass is 0.7mm, the drop height of 180-grit sandpaper is ≥1900mm; Vickers hardness is >600kgf / mm 2 ; Young's modulus>80Gpa; 4PB>800MPa; Anti-drop ball impact strength>0.25J, it has super high drop resistance and better mechanical strength.

[0015] The present invention provides a cover plate, which is prepared by using the lithium aluminum silicate glass. The cover plate has impact resistance, scratch resistance and ultra-high drop resistance performance, and has a longer service life.

[0016] The present invention also provides an electronic device, comprising the cover plate, which has better safety, is easy to maintain, and has good durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of a cross-section of a lithium aluminum silicate glass according to the present invention.

[0018] Figure 2 It is a schematic diagram of a stress curve of lithium aluminosilicate glass of the present invention.

[0019] 1 - Compressive stress layer, 2 - Tensile stress layer, 3 - Glass surface, 4 - DOL - 0. Detailed implementation mode

[0020] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such used data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0022] The present invention will be further described in detail below with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0023] See Figure 1 , the present invention discloses a lithium aluminosilicate glass, comprising a compressive stress layer and a tensile stress layer, wherein the compressive stress layer is the part from the glass surface to DOL - 0, and the remaining is the tensile stress layer; See Figure 2 , the stress curve satisfies 70MPa ≤ |CT - AV| ≤ 120MPa, 100MPa ≤ |CT - CV| ≤ 140MPa; wherein, |CT - AV| is the absolute value of the average tensile stress in the tensile stress layer, and |CT - CV| is the absolute value of the maximum tensile stress in the tensile stress layer; The absolute value of the average slope of the stress distribution from the stress inflection point to DOL-0 is 1.2 to 2.3 MPa / μm, the distance from the stress inflection point to DOL-0 is 0.1 to 0.25t, and the compressive stress in this part is mainly generated by sodium ions; DOL-0 ≥ 0.2t; the absolute value of the average slope of the stress distribution from the glass surface to the stress inflection point is 60 to 250 MPa / μm, the thickness range of this part is 0 to 0.01t, and the compressive stress in this part is mainly provided by potassium ions, where t is the thickness of the lithium aluminosilicate glass; the stress inflection point is the point where the magnitude of the compressive stress changes; Among them, the maximum compressive stress on the glass surface in the compressive stress layer is 700 to 1200 Mpa, and the compressive stress gradually decreases from the glass surface to DOL-0; the K 2 O concentration on the glass surface > 8 wt%; The compressive stress at the stress inflection point ≥ 180 MPa, and the Na 2 O at the inflection point > 11 wt%; the value of CS-50 is above 100 MPa, and CS-50 refers to the compressive stress on the glass surface corresponding to when DOL-0 is 50 μm; Preferably, when the lithium aluminosilicate glass includes the following raw material components: 56 wt% to 59.65 of SiO 2 , 23.1 wt% to 24.65 wt% of Al 2 O 3 , 3.15 wt% to 4.2 wt% of B 2 O 3 , 2.89 wt% to 3.4 wt% of Li 2 O, 3.25 wt% to 4.61 wt% of Na 2 O, 0 wt% to 1.2 wt% of K 2 O, 0 wt% to 0.75 wt% of MgO, 0.85 wt% to 1.36 wt% of CaO, 1.4 wt% to 1.71 wt% of SrO, 0 wt% to 2.15 wt% of P 2 O 5 and 0.15 wt% to 0.21 wt% of SnO 2 , it is obtained by two - step chemical strengthening. By mass percentage, the molten salt used in the first - step chemical strengthening includes 0% to 80% potassium nitrate and 20% to 100% sodium nitrate, the strengthening temperature is 390°C to 500°C, and the time is 3 to 12 h. The molten salt used in the second - step chemical strengthening includes 95% to 100% potassium nitrate and 0% to 5% sodium nitrate, the temperature is 370°C to 480°C, and the time is 15 to 60 min. During the two - step chemical strengthening process, the Na + diffusion coefficient > 220 μm 2 / min, and the K + diffusion coefficient > 2 μm 2 / min. is a solid composite material obtained by chemically strengthening lithium aluminosilicate glass. By performing ion exchange below the glass transition temperature and utilizing the concentration difference, larger alkali metal ions in the salt bath replace the smaller alkali metal ions in the glass. Due to the radius difference, a "jamming" effect occurs among the ions in the glass, thereby generating compressive stress on the glass surface and obtaining the corresponding ion exchange depth simultaneously.

[0024] To further prove the beneficial effects of the present invention, when the lithium aluminosilicate glass includes the following raw material components: 56wt% - 59.65 of SiO 2 、23.1wt% - 24.65 wt% of Al 2 O 3 、3.15wt% - 4.2 wt% of B 2 O 3 、2.89wt% - 3.4 wt% of Li 2 O、3.25wt% - 4.61wt% of Na 2 O、0wt% - 1.2wt% of K 2 O、0wt% - 0.75wt% of MgO、0.85wt% - 1.36wt% of CaO、1.4wt% - 1.71wt% of SrO、0wt% - 2.15wt% of P 2 O 5 and 0.15wt% - 0.21wt% of SnO 2 as an example to design an embodiment and test the glass properties under relevant strengthening processes.

[0025] Sandpaper drop test conditions: Attach the chemically strengthened glass (150mm × 70mm × thickness) to an 180g steel plate to fabricate a test sample; the sandpaper is German-made 180-mesh silicon carbide sandpaper; the drop test starts from 500mm and increases by 100mm each time until the glass breaks, and this height is recorded as the glass breaking height; the number of glass samples for the drop test in each embodiment is 10 pieces, and the average value of the breaking heights in the drop test is used as the average drop breaking height.

[0026] Stress test: Stress-related data such as CS, DOL-0, |CT-AV|, |CT-CV|, etc. are respectively tested using FSM6000LE + SLP1000.

[0027] 4PB test: The upper and lower spans are 20mm / 40mm, the speed is 10mm / min, the diameter of the pressing rod is Φ6 mm, gradually apply pressure until it breaks, and read the value.

[0028] Drop ball test: drop ball fixture (fixture specification edge support width 2mm), 65g steel ball, center point once, drop point 12mm from the edge, starting height 250mm (0.15J), if the sample does not break, rise 100mm each time for limit test.

[0029] The glass components and specific test results of each embodiment are shown in the following table:

[0030] It can be seen that when the tempered glass meets the stress curve conditions provided by the present invention and has a thickness of 0.7 mm, the drop height of 180-grit sandpaper is ≥ 1900 mm; the Vickers hardness is > 600 kgf / mm 2 ; Young's modulus>80Gpa; 4PB>800MPa; Anti-drop ball impact strength>0.25J, with very good anti-drop performance and mechanical properties, which can better meet the development needs of electronic equipment covers.

[0031] The present invention provides a cover plate, which is prepared by using the lithium aluminum silicate glass. The cover plate has impact resistance, scratch resistance and ultra-high drop resistance performance, and has a longer service life.

[0032] The present invention also provides an electronic device, comprising the above-mentioned cover plate. The electronic device has better safety, is easy to maintain, and has good durability. The electronic device comprises at least one of a mobile phone, a phone watch, a display, a tablet computer, and a smart wearable.

[0033] In summary, the present invention provides a lithium aluminosilicate glass, a cover plate and an electronic device, wherein the stress curve thereof satisfies 70MPa≤|CT-AV|≤120MPa, 100MPa≤|CT-CV|≤140MPa; the absolute value of the average slope of the stress distribution from the stress inflection point to DOL-0 is 1.2-2.3MPa / um, the absolute value of the average slope of the stress distribution from the glass surface to the stress inflection point is 60-250MPa / um, and the thickness range from the glass surface to the stress inflection point is 0-0.01t. The lithium aluminosilicate glass strengthening process is adjusted according to the above conditions, so that the strengthened lithium aluminosilicate glass has a specific stress structure, so that the CT value is stabilized in the optimal range of glass strengthening, thereby significantly improving the strength of the strengthened glass while avoiding the self-explosion of the glass or the decrease in the drop performance due to excessive strengthening, thereby improving the production qualification rate of the lithium aluminosilicate glass, reducing the loss, and improving the economy of the glass production.

[0034] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A lithium aluminosilicate glass, characterized in that: It includes a compressive stress layer and a tensile stress layer, wherein the compressive stress layer is the portion from the glass surface to DOL-0, and the rest is a tensile stress layer; The stress curve satisfies 70MPa≤|CT-AV|≤120MPa, 100MPa≤|CT-CV|≤140MPa; wherein, |CT-AV| is the absolute value of the average tensile stress in the tensile stress layer, and |CT-CV| is the absolute value of the maximum tensile stress in the tensile stress layer; The absolute value of the average slope of the stress distribution from the stress inflection point to DOL-0 is 1.2 to 2.3 MPa / um; The absolute value of the average slope of the stress distribution from the glass surface to the stress inflection point is 60 to 250 MPa / um, and the thickness range from the glass surface to the stress inflection point is 0 to 0.01t, where t is the thickness of the lithium aluminum silicate glass.

2. The lithium aluminosilicate glass according to claim 1, characterized in that: The DOL-0≥0.2t, wherein t is the thickness of the lithium aluminum silicate glass.

3. The lithium aluminosilicate glass according to claim 1, characterized in that: In the compressive stress layer, the compressive stress on the glass surface is 700-1200 MPa, and the K2O concentration on the glass surface is greater than 8 wt%.

4. The lithium aluminosilicate glass according to claim 1, characterized in that: The compressive stress at the stress inflection point is ≥180MPa, and the Na2O at the inflection point is >11wt%.

5. The lithium aluminosilicate glass according to claim 1, characterized in that: It includes the following components: 56wt% to 59.65wt% SiO2, 23.1wt% to 24.65wt% Al2O3, 3.15wt% to 4.2wt% B2O3, 2.89wt% to 3.4wt% Li2O, 3.25wt% to 4.61wt% Na2O, 0wt% to 1.2wt% K2O, 0wt% to 0.75wt% MgO, 0.85wt% to 1.36wt% CaO, 1.4wt% to 1.71wt% SrO, 0wt% to 2.15wt% P2O5 and 0.15wt% to 0.21wt% SnO2.

6. The lithium aluminosilicate glass according to claim 5, characterized in that: The result is obtained by adopting two chemical strengthenings. In terms of mass percentage, the molten salt used in the first chemical strengthening includes 0% to 80% potassium nitrate and 20% to 100% sodium nitrate, and the molten salt used in the second chemical strengthening includes 95% to 100% potassium nitrate and 0% to 5% sodium nitrate.

7. The lithium aluminosilicate glass according to claim 6, characterized in that: During the two chemical strengthening processes, Na + Diffusion coefficient>220um 2 / min, K + Diffusion coefficient>2um 2 / min.

8. The lithium aluminosilicate glass according to any one of claims 1 to 7, characterized in that: When the thickness is 0.7mm, the drop height of 180-grit sandpaper is ≥1900mm; Vickers hardness is >600kgf / mm 2 ; Young's modulus>80Gpa; 4PB>800MPa; Drop ball impact strength>0.25J.

9. A cover plate, characterized in that: Prepared using the lithium aluminosilicate glass according to any one of claims 1-8.

10. An electronic device, characterized in that: The invention comprises the cover plate as claimed in claim 9.

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