Lithium aluminosilicate glass, method of making and cover glass

Abstract

The application relates to a lithium-aluminum silicate glass, a preparation method thereof and a cover plate glass. The preparation method of the lithium-aluminum silicate glass comprises the following steps: performing gradient temperature preheating treatment on a semi-finished glass to prepare a first intermediate body; performing first chemical strengthening treatment on the first intermediate body to prepare a second intermediate body; and performing second chemical strengthening treatment on the second intermediate body to prepare the lithium-aluminum silicate glass; wherein the gradient temperature preheating treatment satisfies that the temperature rising rate is 5.5 DEG C / min to 12.5 DEG C / min, the temperature rising time is 25 min to 45 min, and the terminal temperature is 200 DEG C to 400 DEG C. The preparation method can effectively improve the surface compressive stress and ion exchange layer depth of the lithium-aluminum silicate glass, and makes the lithium-aluminum silicate glass show good impact resistance and good drop resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of glass products, in particular to a lithium-aluminum-silicate glass and a preparation method thereof and a cover glass. BACKGROUND

[0002] With the progress of science and technology, the technology of electronic devices such as smart phones, mobile Internet terminals and smart wearable devices is changing rapidly. With the diversified development of application scenarios, consumers have higher requirements for the performance of the cover glass of the touch screen: high strength, thin and light, high transmittance, etc. However, the ultra-thinning of the glass will cause the generation of surface micro-cracks, and even cause the micro-cracks to expand to the inside, resulting in a decrease in mechanical properties such as hardness, compressive strength, bending strength, impact resistance and drop resistance.

[0003] Chemical strengthening, also known as ion exchange strengthening, is a method of introducing surface compressive stress (CS) and forming a depth of layer (DOL) on the surface of the glass to improve the strength of the glass. The glass composition of lithium-aluminum-silicate glass contains Li2O and Na2O, and ion exchange of Li + / Na + and ion exchange of Na + / K + will occur during chemical strengthening, so it is usually necessary to perform two chemical strengthening processes to improve the chemical strengthening effect. However, after two chemical strengthening processes, the surface compressive stress and the depth of ion exchange layer of the lithium-aluminum-silicate glass are still not high enough, and it is difficult to obtain good impact resistance and good drop resistance. SUMMARY

[0004] Therefore, it is necessary to provide a lithium-aluminum-silicate glass and a preparation method thereof and a cover glass to solve the problem that after two chemical strengthening processes, the surface compressive stress and the depth of ion exchange layer of the lithium-aluminum-silicate glass are still not high enough, resulting in difficulty in obtaining good impact resistance and good drop resistance.

[0005] The above-mentioned object of the present application is achieved by the following technical solutions:

[0006] In a first aspect of the present application, a preparation method of a lithium-aluminum-silicate glass is provided, comprising the following steps:

[0007] performing gradient temperature preheating treatment on the semi-finished glass to prepare a first intermediate body;

[0008] performing first chemical strengthening treatment on the first intermediate body to prepare a second intermediate body;

[0009] performing second chemical strengthening treatment on the second intermediate body to prepare the lithium-aluminum-silicate glass

[0010] The gradient temperature pre-treatment satisfies: a temperature rising rate of 5.5-12.5℃ / min, a temperature rising time of 25-45min, and a terminal temperature of 200-400℃.

[0011] In one of the embodiments, the gradient temperature pre-treatment comprises the following steps:

[0012] pre-heating to 300-400℃ at a temperature rising rate of 9.5-12.5℃ / min.

[0013] In one of the embodiments, the gradient temperature pre-treatment comprises the following steps:

[0014] pre-heating to 150-250℃ at a temperature rising rate of 7.5-9.5℃ / min;

[0015] pre-heating to 300-400℃ at a temperature rising rate of 8.0-12.5℃ / min.

[0016] In one of the embodiments, the gradient temperature pre-treatment comprises the following steps:

[0017] pre-heating to 50-150℃ at a temperature rising rate of 5.5-10.5℃ / min;

[0018] pre-heating to 200-300℃ at a temperature rising rate of 9.0-12.5℃ / min;

[0019] pre-heating to 300-400℃ at a temperature rising rate of 6.5-12.0℃ / min.

[0020] In one of the embodiments, the first chemical strengthening treatment comprises the following steps:

[0021] placing the first intermediate into a first molten salt bath at a temperature of 375-465℃ for 60-180min.

[0022] In one of the embodiments, the first molten salt comprises the following components in the following mass ratios: 95-100% of sodium nitrate and 0-5% of potassium nitrate.

[0023] In one of the embodiments, the second chemical strengthening treatment comprises the following steps:

[0024] placing the second intermediate into a second molten salt bath at a temperature of 357-428.5℃ for 60-120min.

[0025] In one of the embodiments, the second molten salt comprises components with the following mass ratio: 95% to 100% of potassium nitrate and 0% to 5% of sodium nitrate.

[0026] In the second aspect of the present application, a lithium aluminosilicate glass is provided, which is prepared by the method for preparing a lithium aluminosilicate glass as described above.

[0027] In the third aspect of the present application, a cover glass is provided, which comprises the lithium aluminosilicate glass as described above.

[0028] The present application has at least the following beneficial effects:

[0029] In the present application, the semi-finished glass is preheated by gradient temperature rising before the two chemical strengthening processes, so that the semi-finished glass is preheated to 300℃ to 400℃ within a temperature rising time of 25 min to 45 min at a temperature rising rate of 5.5℃ / min to 12.5℃ / min. On the one hand, the preheating process can make the glass network structure loose, which is beneficial to improve the ion migration rate and ion exchange rate in the two chemical strengthening processes, so as to obtain a more excellent compressive stress layer. On the other hand, the preheating process can effectively prevent the semi-finished glass from being warped, deformed and broken due to too fast temperature change, so as to reduce the stress relaxation and stress change caused by the preheating process, thereby significantly improving the chemical strengthening effect. Through the gradient temperature rising preheating process and the two chemical strengthening processes, the surface compressive stress and ion exchange layer depth of the lithium aluminosilicate glass can be effectively improved, and the lithium aluminosilicate glass can exhibit good impact resistance and good drop resistance. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0031] In addition, the terms "first", "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] In the present application, the technical features described in an open way include both the closed technical solutions consisting of the listed features and the open technical solutions containing the listed features.

[0034] In the present application, when a numerical interval is involved, unless otherwise specified, the numerical interval is considered to be continuous and includes the minimum value and the maximum value of the range, as well as every value between the minimum value and the maximum value. Further, when the range refers to integers, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0035] In the present application, the percentage content, unless otherwise specified, refers to mass percentage for solid-liquid mixing and solid-solid mixing, and refers to volume percentage for liquid-liquid mixing.

[0036] In the present application, the temperature parameter, unless otherwise specified, allows both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument.

[0037] In the present application, room temperature refers to indoor temperature, normal temperature or general temperature. Generally, the range of room temperature can be any of the following temperature ranges: (1) 23℃±2℃; (2) 25℃±5℃; (3) 20℃±5℃.

[0038] In the first aspect of the present application, a preparation method of lithium aluminum silicate glass is provided to solve the problem that the traditional secondary chemical strengthening of lithium aluminum silicate glass still cannot obtain good impact resistance and drop resistance.

[0039] In some embodiments, the preparation method of lithium aluminum silicate glass comprises the following steps:

[0040] The semi-finished glass is subjected to gradient temperature preheating treatment to prepare a first intermediate;

[0041] The first intermediate is subjected to first chemical strengthening treatment to prepare a second intermediate;

[0042] Performing a second chemical strengthening treatment on the second intermediate to produce a lithium aluminosilicate glass

[0043] The gradient temperature preheating treatment satisfies: a temperature rising rate of 5.5-12.5℃ / min, a temperature rising time of 25-45min, and an end point temperature of 200-400℃.

[0044] It can be understood that the end point temperature refers to the temperature at the end or stop of the gradient temperature preheating treatment, that is, the gradient temperature preheating treatment of the present application includes the following steps: preheating the semi-finished glass to 200-400℃ at a temperature rising rate of 5.5-12.5℃ / min within a temperature rising time of 25-45min.

[0045] The present application preheats the semi-finished glass to 300-400℃ at a temperature rising rate of 5.5-12.5℃ / min within a temperature rising time of 25-45min before the two chemical strengthening treatments, which can loosen the glass network structure through preheating, facilitate the ion migration rate and ion exchange rate in the two chemical strengthening treatments, and thus obtain a more excellent compressive stress layer, and can effectively prevent the semi-finished glass from being warped, deformed, and broken due to too fast temperature change, reduce stress relaxation and stress change during the preheating process, and thus significantly improve the chemical strengthening effect. Through the gradient temperature preheating treatment and the two chemical strengthening treatments of the present application, the surface compressive stress and ion exchange layer depth of the lithium aluminosilicate glass can be effectively improved, and the lithium aluminosilicate glass exhibits good impact resistance and good drop resistance.

[0046] In the present application, the end point temperature of the gradient temperature preheating treatment is denoted as T, the preheating time of the gradient temperature preheating treatment is denoted as t, and the temperature rising rate of the gradient temperature preheating treatment is denoted as k, so that:

[0047] The end point temperature T of the gradient temperature preheating treatment is 200-400℃, including but not limited to 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, 320℃, 340℃, 360℃, 380℃, and 400℃, further optionally 300-400℃, and more further optionally 320-380℃.

[0048] The preheating time t of the gradient temperature preheating treatment is 25-45min, including but not limited to 25min, 27min, 30min, 32min, 34min, 36min, 38min, 40min, 42min, and 45min, and further optionally 30-40min.

[0049] The heating rate k of the gradient heating preheating treatment is 5.5-12.5°C / min, including but not limited to 5.5°C / min, 6°C / min, 6.5°C / min, 7°C / min, 7.5°C / min, 8°C / min, 8.5°C / min, 9°C / min, 9.5°C / min, 10°C / min, 10.5°C / min, 11°C / min, 11.5°C / min, 12°C / min and 12.5°C / min, and further optionally 9-12.5°C / min.

[0050] Before the gradient heating preheating treatment, the temperature of the semi-finished glass is room temperature, and the temperature range can be 20-30°C, including but not limited to 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C and 30°C, and further optionally 24-26°C.

[0051] It can be understood that the gradient heating preheating treatment of the present application can meet the three conditions of the heating rate k of 5.5-12.5°C / min, the heating time t of 25-45 min and the end temperature T of 200-400°C. The heating rate k can be a constant value in the range of 5.5-12.5°C / min, or the heating rate k can fluctuate in the range of 5.5-12.5°C / min. In the gradient heating preheating treatment process, the heating rate k can be a constant value in the range of 5.5-12.5°C / min for a period of time, and fluctuate in the range of 5.5-12.5°C / min for another period of time.

[0052] In some embodiments, the gradient heating preheating treatment includes at least one round of gradient heating preheating treatment, and the heating rate of each round of gradient heating preheating treatment is independently 5.5-12.5°C / min.

[0053] It can be understood that the number of rounds of gradient heating preheating treatment is n, and n is a natural number not less than 1, including but not limited to 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, and further optionally 1-5, and more further optionally 1-3.

[0054] In some embodiments, the number of rounds of gradient heating preheating treatment is one, and the gradient heating preheating treatment includes the following steps:

[0055] Preheating to 300-400°C at a heating rate of 9.5-12.5°C / min.

[0056] Understandably, in a single-round gradient heating preheating treatment, the heating rate k = 9.5℃ / min~12.5℃ / min, including but not limited to: 9.5℃ / min, 10℃ / min, 10.5℃ / min, 11℃ / min, 11.5℃ / min, 12℃ / min and 12.5℃ / min, and further selectable as 10.1℃ / min~11.8℃ / min; the final temperature T = 300℃~400℃, and further selectable as 320℃~380℃; the heating time t = 25min~35min, including but not limited to: 25min, 28min, 30min, 32min and 35min, and further selectable as 30min~35min.

[0057] In some implementations, the gradient temperature preheating process consists of two rounds, and includes the following steps:

[0058] Preheat to 150℃~250℃ at a heating rate of 7.5℃ / min~9.5℃ / min;

[0059] Preheat to 300℃~400℃ at a heating rate of 8.0℃ / min~12.5℃ / min.

[0060] Understandably, in the two-round gradient heating preheating treatment, the heating rate of the first round of gradient heating preheating treatment is k1 = 7.5℃ / min~9.5℃ / min, including but not limited to: 7.5℃ / min, 8.0℃ / min, 8.5℃ / min, 9.0℃ / min and 9.5℃ / min, and can be further selected as 8.3℃ / min~9.0℃ / min; the final temperature of the first round of gradient heating preheating treatment is T1 = 150℃~250℃, including but not limited to: 150℃, 180℃, 200℃, 220℃, 240℃ and 250℃. The heating rate of the second round of gradient heating preheating treatment, k2, is 8.0℃ / min to 12.5℃ / min, including but not limited to: 8.0℃ / min, 9.0℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, and 12.5℃ / min, and can be further selected as 10℃ / min to 12℃ / min; the final temperature of the first round of gradient heating preheating treatment, T2, is 300℃ to 400℃, and can be further selected as 320℃ to 380℃. The total heating time, t, is 30min to 42min, including but not limited to: 30min, 32min, 34min, 36min, 38min, 40min, and 42min, and can be further selected as 34min to 42min.

[0061] In some implementations, the gradient temperature preheating process consists of three rounds, and includes the following steps:

[0062] preheating to 50℃~150℃ at a temperature increasing rate of 5.5℃ / min~10.5℃ / min;

[0063] preheating to 200℃~300℃ at a temperature increasing rate of 9.0℃ / min~12.5℃ / min;

[0064] preheating to 300℃~400℃ at a temperature increasing rate of 6.5℃ / min~12.0℃ / min.

[0065] It can be understood that in the three-round gradient temperature preheating treatment, the temperature increasing rate k1 of the first round of gradient temperature preheating treatment is 5.5℃ / min~10.5℃ / min, including but not limited to: 5.5℃ / min, 6.5℃ / min, 7.5℃ / min, 8.5℃ / min, 9.5℃ / min and 10.5℃ / min, and further optionally 6.3℃ / min~10.4℃ / min; the end point temperature T1 of the first round of gradient temperature preheating treatment is 150℃~250℃, including but not limited to: 150℃, 180℃, 200℃, 220℃, 240℃ and 250℃. The temperature increasing rate k2 of the second round of gradient temperature preheating treatment is 9.0℃ / min~12.5℃ / min, including but not limited to: 9.0℃ / min, 10℃ / min, 11℃ / min, 12℃ / min and 12.5℃ / min, and further optionally 10℃ / min~12℃ / min; the end point temperature T2 of the second round of gradient temperature preheating treatment is 200℃~300℃, including but not limited to: 200℃, 220℃, 240℃, 260℃, 280℃ and 300℃. The temperature increasing rate k3 of the third round of gradient temperature preheating treatment is 6.5℃ / min~12.0℃ / min, including but not limited to: 6.5℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min and 12℃ / min, and further optionally 6.5℃ / min~9.0℃ / min; the end point temperature T3 of the third round of gradient temperature preheating treatment is 300℃~400℃, and further optionally 320℃~380℃; the total temperature increasing time t is 26min~42min, including but not limited to: 26min, 28min, 30min, 32min, 34min, 36min, 38min, 40min and 42min, and further optionally 34min~42min.

[0066] The present application can make the network structure of the semi-finished glass slowly and safely loose through multiple rounds of gradient temperature preheating, which is beneficial to expand the ion gap of the internal structure and accelerate the ion migration rate and ion exchange rate; at the same time, the multiple rounds of gradient temperature preheating can also make the internal structure of the semi-finished glass gradually adapt to the thermal shock of the preheating process, prevent the sharp change of the internal residual stress of the semi-finished glass from producing strong impact on the body structure, and ensure that the glass will not crack or warp during the preheating and strengthening process.

[0067] In some embodiments, the first chemical strengthening process comprises the following steps:

[0068] The first intermediate is placed in a first molten salt bath at a temperature of 375-465°C for 60-180 minutes.

[0069] Understandably, let the temperature of the first molten salt be T', and the salt bath time of the first intermediate in the first molten salt be t', then the first chemical strengthening process should satisfy: T' = -0.25t' + (450 ± 30). Wherein, the temperature of the first molten salt is T' = 375-465°C, including but not limited to: 375°C, 385°C, 395°C, 405°C, 415°C, 425°C, 435°C, 445°C, 455°C and 465°C, further optionally 425-465°C. The salt bath time of the first intermediate in the first molten salt is t' = 60-180 minutes, including but not limited to: 60 minutes, 80 minutes, 100 minutes, 120 minutes, 140 minutes, 160 minutes and 180 minutes, further optionally 80-100 minutes.

[0070] In some embodiments, the first molten salt comprises the following components in mass percentage: sodium nitrate (NaNO3) 95-100% and potassium nitrate (KNO3) 0-5%. Wherein, the mass percentage of NaNO3 in the first molten salt can be 95%, 96%, 97%, 98%, 99% and 100%, further optionally 98-100%; the mass percentage of KNO3 in the first molten salt can be 0%, 1%, 2%, 3%, 4% and 5%, further optionally 0-2%.

[0071] In some embodiments, the second chemical strengthening process comprises the following steps:

[0072] The second intermediate is placed in a second molten salt bath at a temperature of 357-428.5°C for 60-120 minutes.

[0073] It can be understood that the temperature of the second molten salt is T", and the salt bath time of the second intermediate in the second molten salt is t", and the second chemical strengthening treatment should satisfy: T" = -0.525t" + (440 ± 20). Wherein, the temperature of the second molten salt is T" = 357℃ ~ 428.5℃, including but not limited to: 357℃, 360℃, 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, 425℃ and 428.5℃, and further can be selected as 380℃ ~ 400℃. The salt bath time of the second intermediate in the second molten salt is t" = 60min ~ 120min, including but not limited to: 60min, 70min, 80min, 90min, 100min, 100min and 120min, and further can be selected as 60min ~ 80min.

[0074] In some embodiments, the second molten salt includes components with the following mass ratio: potassium nitrate (KNO3) 95% ~ 100% and sodium nitrate (NaNO3) 0% ~ 5%. Wherein, the mass ratio of KNO3 in the second molten salt can be 95%, 96%, 97%, 98%, 99% and 100%, and further can be selected as 95% ~ 97%; the mass ratio of NaNO3 in the second molten salt can be 0%, 1%, 2%, 3%, 4% and 5%, and further can be selected as 3% ~ 5%.

[0075] It can be understood that factors affecting ion diffusion and migration will affect the effect of chemical strengthening. Generally, in the process of chemical strengthening, increasing the temperature and prolonging the holding time are beneficial to the ion exchange process. However, too high molten salt temperature and too long holding time will make the glass appear stress relaxation phenomenon, so that the glass strength decreases. Therefore, on the basis of gradient temperature preheating treatment, the molten salt temperature and salt bath time of the two chemical strengthening treatments are strictly controlled, so that the first intermediate and the second intermediate can present a relatively loose network structure, and rapid ion exchange is carried out in a suitable temperature and time range, so as to obtain a more high-quality compressive stress layer, and further improve the impact resistance and drop resistance of the glass.

[0076] In some embodiments, the semi-finished glass includes components with the following mass ratio:

[0077] SiO255% ~ 75.5%,

[0078] Al2O315.5% ~ 18.5%,

[0079] R2O5% ~ 10%,

[0080] Li2O4% ~ 12%,

[0081] MgO3% ~ 5%,

[0082] ZnO 2%~3%, and

[0083] ZrO2 0.5%~1.5%;

[0084] wherein, R2O includes Na2O and K2O.

[0085] Further optionally, the semi-finished glass includes the following components with the following mass ratios:

[0086] SiO2 67%~72.5%,

[0087] Al2O3 16.5%~17.5%,

[0088] R2O 6%~8%,

[0089] Li2O 8%~10.5%,

[0090] MgO 3.5%~4.5%,

[0091] ZnO 2%~3%, and

[0092] ZrO2 0.75%~1.05%.

[0093] In the second aspect, the application provides a preparation method of the lithium-aluminum silicate glass.

[0094] Optionally, the CS-30 of the lithium-aluminum silicate glass is greater than or equal to 130 MPa, including but not limited to 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa and 200 MPa, and further optionally 131.3 MPa~170 MPa.

[0095] Optionally, the CS-50 of the lithium-aluminum silicate glass is greater than or equal to 120 MPa, including but not limited to 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa and 180 MPa, and further optionally 124 MPa~140 MPa.

[0096] Optionally, the DOL-0 of the lithium-aluminum silicate glass is greater than or equal to 120 μm, including but not limited to 120 μm, 125 μm, 130 μm, 135 μm, 140 μm, 145 μm and 150 μm, and further optionally 125 μm~140 μm.

[0097] Optionally, the lithium aluminosilicate glass has a CS-K≥920 MPa, including but not limited to 920 MPa, 950 MPa, 1000 MPa, 1050 MPa, 1100 MPa, 1150 MPa, and 1200 MPa, and further optionally 930 MPa to 1000 MPa.

[0098] Optionally, the lithium aluminosilicate glass has a DOL-K≥4 μm, including but not limited to 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, and 10 μm, and further optionally 5 μm to 8 μm.

[0099] In the present application, the lithium aluminosilicate glass is subjected to gradient temperature preheating treatment and twice chemical strengthening treatment, and a high-quality compressive stress layer is formed on the surface, and the surface compressive stress and ion exchange layer depth are obviously improved. Among them, CS-30 represents the compressive stress at a depth of 30 μm, CS-50 represents the compressive stress at a depth of 50 μm of the compressive stress layer, DOL-0 represents the depth of the sodium ion stress layer, CS-K represents the compressive stress of the potassium ion stress layer, and DOL-K represents the depth of the potassium ion stress layer.

[0100] Optionally, the lithium aluminosilicate glass has a drop ball height≥70 cm, including but not limited to 70 cm, 80 cm, 90 cm, 100 cm, 105 cm, 110 cm, 115 cm, 120 cm, 125 cm, 130 cm, 135 cm, 140 cm, 145 cm, and 150 cm, and further optionally 90 cm to 130 cm, and further optionally 110 cm to 130 cm.

[0101] Optionally, the lithium aluminosilicate glass has an impact energy≥0.220 J, including but not limited to 0.220 J, 0.240 J, 0.26 J, 0.280 J, 0.300 J, 0.320 J, 0.340 J, 0.360 J, 0.380 J, 0.400 J, 0.420 J, 0.440 J, 0.460 J, 0.480 J, and 0.500 J, and further optionally 0.300 J to 0.410 J.

[0102] Optionally, the lithium aluminosilicate glass has a drop height≥100 cm, including but not limited to 100 cm, 105 cm, 110 cm, 115 cm, 120 cm, 125 cm, 130 cm, 135 cm, 140 cm, 145 cm, and 150 cm, and further optionally 110 cm to 130 cm.

[0103] Benefited from the high-quality compressive stress layer on the surface, the lithium aluminosilicate glass of the present application has a significant improvement in the ball drop height, impact resistance energy and drop height, and exhibits excellent impact resistance and drop resistance.

[0104] In a third aspect, the present application provides a cover glass comprising the lithium aluminosilicate glass as described above.

[0105] The present application will be further described in detail in connection with specific examples.

[0106] In the following specific examples and comparative examples, the raw materials used are commercially available products unless otherwise specified; the instruments used are commercially available products unless otherwise specified; and the processes used are routinely selected by those skilled in the art unless otherwise specified. Among them, the semi-finished glass is selected from the sixth-generation glass of Kirinwang of Nanjing Crystal Group, and the size thereof is (165.5±0.01) mm×(82.5±0.01) mm×(0.6±0.01) mm.

[0107] Example 1

[0108] Referring to Table 1, the preparation method of the lithium aluminosilicate glass comprises the following steps:

[0109] (1) Single-stage gradient temperature rising treatment: the semi-finished glass is preheated from 25°C (room temperature) to 320°C at a temperature rising rate of 11.8°C / min, and the preheating time is 25 min, to obtain a first intermediate.

[0110] (2) First chemical strengthening treatment: the first intermediate is placed in a first molten salt bath at a temperature of 445°C for 90 min to obtain a second intermediate; wherein the first molten salt is composed of 98wt.% NaNO3 and 2wt.% KNO3, i.e. Na:K=98:2.

[0111] (3) Second chemical strengthening treatment: the second intermediate is placed in a second molten salt bath at a temperature of 390°C for 60 min to obtain the lithium aluminosilicate glass; wherein the second molten salt is composed of 96wt.% KNO3 and 4wt.% NaNO3, i.e. K:Na=96:4.

[0112] Examples 2-9

[0113] Examples 2-9 are also single-stage gradient preheating treatment, and the specific process parameters are shown in Table 1.

[0114] Example 10

[0115] The difference between this example and Example 1 is that this example adopts two-stage gradient temperature rising preheating treatment.

[0116] Referring to Table 2, the preparation method of the lithium aluminosilicate glass comprises the following steps:

[0117] (1) Two-round gradient preheating treatment:

[0118] Preheating from 25℃ to 150℃ at a heating rate of 8.3℃ / min, and the preheating time is 15min;

[0119] Preheating from 150℃ to 320℃ at a heating rate of 10.6℃ / min, and the preheating time is 16min, to obtain a first intermediate.

[0120] (2) First chemical strengthening treatment: placing the first intermediate in a first molten salt bath at a temperature of 445℃ for 90min to obtain a second intermediate; wherein the first molten salt is composed of 98wt.% NaNO3 and 2wt.% KNO3, i.e. Na:K=98:2.

[0121] (3) Second chemical strengthening treatment: placing the second intermediate in a second molten salt bath at a temperature of 390℃ for 60min to obtain the lithium aluminosilicate glass; wherein the second molten salt is composed of 96wt.% KNO3 and 4wt.% NaNO3, i.e. K:Na=96:4.

[0122] Examples 11-18

[0123] Examples 11-18 are also two-round gradient preheating treatment, and the specific process parameters are shown in Table 2.

[0124] Example 19

[0125] The difference between this example and Example 1 is that this example adopts three-round gradient preheating treatment.

[0126] Referring to Table 3, the preparation method of the lithium aluminosilicate glass comprises the following steps:

[0127] (1) Two-round gradient preheating treatment:

[0128] Preheating from 25℃ to 50℃ at a heating rate of 6.3℃ / min, and the preheating time is 4min;

[0129] Preheating from 50℃ to 200℃ at a heating rate of 12.5℃ / min, and the preheating time is 12min;

[0130] Preheating from 200℃ to 320℃ at a heating rate of 12.0℃ / min, and the preheating time is 10min, to obtain a first intermediate.

[0131] (2) first chemical strengthening treatment: placing the first intermediate body in a first molten salt with a temperature of 445°C for 90 min to obtain a second intermediate body; wherein the first molten salt is composed of 98wt.% NaNO3 and 2wt.% KNO3, i.e. Na:K = 98:2.

[0132] (3) second chemical strengthening treatment: placing the second intermediate body in a second molten salt with a temperature of 390°C for 60 min to obtain a lithium-aluminum silicate glass; wherein the second molten salt is composed of 96wt.% KNO3 and 4wt.% NaNO3, i.e. K:Na = 96:4.

[0133] Examples 20-27

[0134] Examples 20-27 are also three-stage gradient preheating treatments, and the specific process parameters are shown in Table 3.

[0135] Comparative Examples 1-8

[0136] See Table 4 for the following:

[0137] Comparative Example 1: no preheating treatment;

[0138] Comparative Example 2: constant temperature preheating at 380°C for 40 min;

[0139] Comparative Example 3: single-stage gradient preheating treatment, preheating to 380°C at a heating rate of 4.5°C / min;

[0140] Comparative Example 4: single-stage gradient preheating treatment, preheating to 380°C at a heating rate of 14°C / min;

[0141] Comparative Example 5: two-stage gradient preheating treatment, preheating to 250°C at a heating rate of 4°C / min, and preheating to 380°C at a heating rate of 8°C / min;

[0142] Comparative Example 6: two-stage gradient preheating treatment, preheating to 250°C at a heating rate of 11°C / min, and preheating to 380°C at a heating rate of 13°C / min;

[0143] Comparative Example 7: three-stage gradient preheating treatment, preheating to 150°C at a heating rate of 4°C / min, preheating to 300°C at a heating rate of 8°C / min, and preheating to 380°C at a heating rate of 6°C / min;

[0144] Comparative Example 8: three-stage gradient preheating treatment, preheating to 150°C at a heating rate of 11°C / min, preheating to 300°C at a heating rate of 13°C / min, and preheating to 380°C at a heating rate of 13.5°C / min.

[0145] Test Examples

[0146] (1) Stress test: The CS-30, CS-50 and DOL-0 of lithium aluminum silicate glass were tested using the SLP 2000 glass stress tester of Orihara, Japan, and the CS-K and DOL-K of lithium aluminum silicate glass were tested using the FSM 6000 Leuv stress tester of Orihara, Japan. The results are shown in Table 5.

[0147] (2) Impact resistance test: The impact energy of lithium aluminum silicate glass was tested using a Psert falling ball impact tester. The glass sample was fixed in a fixture with the 2.5D side (all glass samples were double-strengthened, the 2.5D side being the processed surface, i.e., the contact surface in actual use) facing upwards. A 65g ball was dropped vertically from a height of 5cm to the center of the glass. This test was repeated three times. If the glass sample did not break, the height was increased by 5cm each time, and the test was repeated until the glass sample broke. The height of the steel ball (h / m) and the mass of the steel ball (m / kg) at the time of breakage were recorded. The results were then calculated using the formula W=mgh (g=9.8m / s²). 2 The results are shown in Table 5.

[0148] (3) Drop resistance test: The drop resistance height of lithium aluminum silicate glass was tested using a mobile phone controlled drop tester. The 2D surface of the glass sample was attached and fixed to a 200g steel counterweight to obtain a test module. The test module was placed in the mobile phone controlled drop tester, and 180-grit gold sun sandpaper was used to simulate the drop surface. The 2.5D surface of the glass sample was facing the sandpaper, and the initial height was set to 50cm. The glass was dropped freely. If the glass did not break, the height was increased by 10cm in sequence and the test was repeated until the glass broke. The height at this point is the drop height. The results are shown in Table 5.

[0149] As shown in Table 5, compared with Comparative Examples 1-8, CS-30, CS-50, DOL-0, CS-K, and DOL-K of Examples 1-27 all showed significant improvements. This indicates that using gradient heating preheating treatment and controlling the heating rate within the range of 5.5℃ / min to 12.5℃ / min can achieve better chemical strengthening of lithium aluminum silicate glass, thereby forming a higher-quality compressive stress layer. Thanks to the high-quality compressive stress layer, the lithium aluminum silicate glass of Examples 1-27 also showed significant improvements in impact resistance and drop resistance.

[0150] Among them, the chemical strengthening effect of Example 27 is the best, the semi-finished glass needs to be annealed to eliminate its internal stress (or thermal stress, residual stress) during production process, but generally cannot be completely eliminated, and there is still residual stress inside, through multiple rounds of gradient heating treatment, and reasonable control of heating rate, heating time and end temperature, can prevent the residual stress inside the semi-finished glass from changing sharply to cause the glass to crack, and make the glass network structure become loose, and the ion gap is fully expanded, so the ion migration rate and ion exchange rate are obviously improved, thereby forming a high-quality, high-strength compressive stress layer on the surface of the glass.

[0151] Table 1. Process parameters of Examples 1-9

[0152]

[0153] Table 2. Process parameters of Examples 10-18

[0154]

[0155] Table 3. Process parameters of Examples 19-27

[0156]

[0157] Table 4. Process parameters of Comparative Examples 1-8

[0158]

[0159] Table 5. Performance comparison of Examples 1-27 and Comparative Examples 1-8

[0160]

[0161] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict each other, they should be considered within the scope of the present disclosure.

[0162] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims, and the description can be used to explain the content of the claims.

Claims

1. A method of making a lithium aluminosilicate glass, characterized by, The method comprises the following steps: performing gradient temperature preheating treatment on the semi-finished glass to prepare a first intermediate body; performing first chemical strengthening treatment on the first intermediate body to prepare a second intermediate body; performing second chemical strengthening treatment on the second intermediate body to prepare the lithium-aluminum silicate glass; the gradient temperature preheating treatment satisfies: a temperature rising rate of 9.5-12.5 ℃ / min, a temperature rising time of 25-45 min, and a terminal temperature of 300-400 ℃; the semi-finished glass comprises the following components in a mass percentage: SiO2 55-75.5%, Al2O3 15.5-18.5%, R2O 5-10%, Li2O 4-12%, MgO 3-5%, ZnO 2-4%, and ZrO2 0.5-1.5%; R2O comprises Na2O and K2O; the sum of the mass percentages of the components of the semi-finished glass is 100%.

2. A method of making a lithium aluminosilicate glass characterized by, The method comprises the following steps: performing gradient temperature preheating treatment on the semi-finished glass to prepare a first intermediate body; performing first chemical strengthening treatment on the first intermediate body to prepare a second intermediate body; performing second chemical strengthening treatment on the second intermediate body to prepare the lithium-aluminum silicate glass; the gradient temperature preheating treatment satisfies: a temperature rising time of 25-45 min; preheating to 150-250 ℃ at a temperature rising rate of 7.5-9.5 ℃ / min; preheating to 300-400 ℃ at a temperature rising rate of 8.0-12.5 ℃ / min; the semi-finished glass comprises the following components in a mass percentage: SiO2 55-75.5%, Al2O3 15.5-18.5%, R2O 5-10%, Li2O 4-12%, MgO 3-5%, ZnO 2-4%, and ZrO2 0.5-1.5%; R2O comprises Na2O and K2O; the sum of the mass percentages of the components of the semi-finished glass is 100%.

3. A method of making a lithium aluminosilicate glass, characterized by, The method comprises the following steps: performing gradient temperature preheating treatment on the semi-finished glass to prepare a first intermediate body; performing first chemical strengthening treatment on the first intermediate body to prepare a second intermediate body; performing second chemical strengthening treatment on the second intermediate body to prepare the lithium-aluminum silicate glass; the gradient temperature preheating treatment satisfies: a temperature rising time of 25-45 min; preheating to 50-150 ℃ at a temperature rising rate of 5.5-10.5 ℃ / min; preheating to 200-300 ℃ at a temperature rising rate of 9.0-12.5 ℃ / min; preheating to 300-400 ℃ at a temperature rising rate of 6.5-12.0 ℃ / min; the semi-finished glass comprises the following components in a mass percentage: SiO2 55-75.5%, Al2O3 15.5-18.5%, R2O 5-10%, Li2O 4-12%, MgO 3-5%, ZnO 2-4%, and ZrO2 0.5-1.5%; R2O comprises Na2O and K2O; The sum of the mass proportions of the components of the semi-finished glass is 100%.

4. The method of making lithium aluminosilicate glass according to any one of claims 1 to 3, wherein The first chemical strengthening treatment comprises the following steps: The first intermediate is placed in a first molten salt bath at a temperature of 375-465℃ for 60-180 minutes.

5. The method of making lithium aluminosilicate glass of claim 4, wherein, The first molten salt comprises the following mass proportions of components: 95-100% sodium nitrate and 0-5% potassium nitrate.

6. The method of making lithium aluminosilicate glass of claim 5, wherein, The second chemical strengthening treatment comprises the following steps: The second intermediate is placed in a second molten salt bath at a temperature of 357-428.5℃ for 60-120 minutes.

7. The method of making lithium aluminosilicate glass of claim 6, wherein, The second molten salt comprises the following mass proportions of components: 95-100% potassium nitrate and 0-5% sodium nitrate.

8. A lithium aluminosilicate glass characterized by, The lithium aluminosilicate glass is prepared by the method of any one of claims 1-7.

9. A cover glass, characterized by The lithium aluminosilicate glass comprises the lithium aluminosilicate glass of claim 8.

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