Glass strengthening method, strengthened glass and protective film

Abstract

The invention provides a glass strengthening method, strengthened glass and a protective film, the glass is lithium-aluminum-silicon glass, the glass strengthening method comprises the following steps: (1) performing CNC (computer numerical control) corner polishing on cut glass; (2) after CNC corner grinding, sweeping to polish the surface of the glass; (3) carrying out etching treatment for the first time after sweeping; (4) tempering treatment is carried out after the first-time etching treatment so that ion exchange can be carried out on the glass and tempering salt, the tempering treatment comprises first-time tempering and second-time tempering, the temperature of the first-time tempering is 380-440 DEG C, and the duration is 1.5-3 hours; the temperature of the second tempering is 370 DEG C to 420 DEG C, and the duration is 0.5 to 1.5 hours. The tempered glass and the protective film which are obtained by the glass strengthening method have relatively good anti-falling performance and impact resistance, and the use experience of a user is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of strengthened glass processing, in particular to a glass strengthening method, strengthened glass and a protective film. BACKGROUND

[0002] The tempered glass protective film is used to be attached to the surface of the screen of an electronic product to prevent the screen from being broken when the electronic product is accidentally dropped, and the protective film itself also needs to ensure certain performance to avoid the problem of easy breakage when dropped. The protective film made of lithium aluminum silicon glass can be improved in drop resistance due to the material properties, but the drop resistance and impact resistance of the glass strengthened by the traditional glass strengthening process still need to be improved. SUMMARY

[0003] Therefore, in order to overcome at least part of the defects and deficiencies in the prior art, the present application provides a glass strengthening method, strengthened glass and a protective film, which have better drop resistance and ball impact resistance, and can obtain a protective film with higher strength to improve the user experience.

[0004] Specifically, in one aspect, the embodiments of the present application provide a glass strengthening method, the glass being lithium aluminum silicon glass, the glass strengthening method comprising the following steps: (1) performing CNC corner polishing on the cut glass; (2) performing light scanning to polish the surface of the glass after the CNC corner polishing; (3) performing first etching treatment after the light scanning; (4) performing tempering treatment to make the glass ion exchange with a tempering salt after the first etching treatment, the tempering treatment comprising first tempering and second tempering, the temperature of the first tempering being 380-440°C, and the time being 1.5-3 hours; the temperature of the second tempering being 370-420°C, and the time being 0.5-1.5 hours.

[0005] In some embodiments, the temperature of the first tempering is 385-395°C, and the time is 2.3-2.7 hours; the temperature of the second tempering is 375-385°C, and the time is 0.8-1.2 hours.

[0006] In some embodiments, the tempering treatment further comprises third tempering, the temperature of the third tempering being 385-395°C, and the time being 8-12 min.

[0007] In some embodiments, the tempering salt used in the first tempering is a mixture of 45-55% potassium nitrate and 45-55% sodium nitrate by mass percentage; the tempering salt used in the second tempering is a mixture of 92-98% potassium nitrate and 2-8% sodium nitrate by mass percentage.

[0008] In some embodiments, the thickness of the glass thinned in the first etching process is 5-8 microns.

[0009] In some embodiments, the glass strengthening method further comprises: (5) performing a second etching process after the tempering process, the thickness of the second etching process being 2-3 microns.

[0010] In some embodiments, the glass strengthening method further comprises performing an etching process between CNC corner polishing and edging to thin the thickness of the glass by 7-10 microns.

[0011] In some embodiments, the etching solution in the first etching process comprises the following components in percentage by mass: water 75-80%, hydrofluoric acid 20-25%.

[0012] The embodiments of the present application also provide a strengthened glass obtained by strengthening a lithium-aluminum-silicon glass by the glass strengthening method of any one of the preceding embodiments.

[0013] The embodiments of the present application also provide a tempered film comprising the strengthened glass.

[0014] The embodiments of the present application have at least the following beneficial effects: the first etching process before the tempering process processes a part of the surface micro-cracks of the glass to improve the strength of the glass, and the multiple tempering with specific temperature and time range can improve the drop resistance and ball impact resistance of the glass, thereby improving the strength of the glass and effectively improving the quality of the product. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0016] Figure 1 The step flowchart of the glass strengthening method provided by the embodiments of the present application is shown. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments described in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0018] With reference toFigure 1 The embodiment of the present application provides a glass strengthening method, the glass is lithium aluminosilicate glass, and the glass strengthening method comprises the following steps: (1) performing CNC corner polishing on the glass after cutting; (2) performing polishing after the CNC corner polishing to polish the glass surface; (3) performing first etching treatment after the polishing; (4) performing tempering treatment to make the glass ion exchange with a tempering salt after the first etching treatment, the tempering treatment comprises first tempering and second tempering, the temperature of the first tempering is 380-440 DEG C, and the time length is 1.5-3 hours; the temperature of the second tempering is 370-420 DEG C, and the time length is 0.5-1.5 hours.

[0019] The lithium aluminosilicate glass is an aluminosilicate glass system with Li2O-Al2O3-SiO2 as a skeleton and introducing appropriate amounts of Na2O, K2O, MgO, ZrO2 and other oxides. The thickness of the glass in the glass strengthening method provided by the application is not limited, generally speaking, the thicker the thickness is, the stronger the drop resistance, the ball impact resistance and the edge compression strength can be. For example, the glass used in the application is mainly used for manufacturing glass protective films of electronic products such as mobile phones or tablet computers, and the thickness range can be selected between 0.15 and 0.8 mm.

[0020] Cutting refers to cutting a large piece of glass material into multiple small pieces of glass with appropriate sizes according to the required size. CNC (Computer Numerical Control) corner polishing is used to polish the corners of the cut glass into an arc shape to adapt to the shape of the electronic screen, and the embodiment is polished twice, for example, a 400-mesh polishing head is used for preliminary forming, and a 900-1200-mesh polishing head is used for finishing. Different precision polishing can be achieved by using different parts of the length direction of the polishing head during the two CNC corner polishing. After the CNC corner polishing, microcracks will be generated on the edge of the glass surface, and the second finishing can make the microcracks on the edge of the glass surface more subtle. The second polishing is preferably performed using a 1200-mesh polishing head.

[0021] The polishing can thin the glass by 2-3 microns and can repair the fine scratches on the glass surface. The polishing time is 150-200 s, and the pressure acting on the glass surface is 4-5 kg / cm 2 , for example, the pressure is 4 kg / cm 2 and the time is 150 s, or the pressure is 5 kg / cm 2 and the time is 160 s, or the pressure is 4 kg / cm2 and the time length is 200s, etc., preferably the pressure is 5kg / cm 2 and the time length is 160s, better edge strength can be obtained.

[0022] For example, the temperature of the first tempering can be 380℃, 390℃, 400℃, 410℃, 420℃, 430℃, 440℃, etc. The time length of the first tempering can be 1.5h, 2h, 2.5h, 3h, etc. The temperature of the second tempering can be 370℃, 380℃, 390℃, 400℃, 410℃, 420℃, etc. The time length of the second tempering can be 0.5h, 1h, 1.5h, etc. The temperature and time length combination of the first tempering can be 390℃ / 1.5H, 390℃ / 2.5H, 440℃ / 2H, etc. For example, the temperature and time length combination of the second tempering can be 380℃ / 1H, 380℃ / 1.5H, 420℃ / 1.5H, etc. The temperature and time length of the first and second tempering are both set temperature and time length, and the actual temperature in the tempering furnace and the actual time length of staying in the tempering furnace are allowed to have certain errors. During tempering, the glass is first put into a preheating furnace for preheating, and then put into a tempering furnace for tempering. The temperature difference between the preheating furnace and the tempering furnace is less than or equal to 30℃.

[0023] In some embodiments, the tempering salt used in the first tempering is a mixture of 45%~55% potassium nitrate and 45%~55% sodium nitrate by mass percentage. For example, the mass percentage of potassium nitrate and sodium nitrate in the tempering salt used in the first tempering is 50%:50%; or the mass percentage of potassium nitrate and sodium nitrate is 45%:55%; or the mass percentage of potassium nitrate and sodium nitrate is 55%:45%, etc. The tempering salt used in the second tempering is a mixture of 92%~98% potassium nitrate and 2%~8% sodium nitrate by mass percentage; for example, the mass percentage of potassium nitrate and sodium nitrate in the tempering salt used in the second tempering is 95%:5%; or the mass percentage of potassium nitrate and sodium nitrate is 93%:7%; or the mass percentage of potassium nitrate and sodium nitrate is 96%:4%, etc. The concentration of potassium nitrate and sodium nitrate in the tempering salt used in the first and second tempering should be above 99.9%. In the first tempering, the sodium ions in the tempering salt mainly replace the lithium ions in the glass, and in the second tempering, the potassium ions in the tempering salt replace the sodium ions in the glass, which can improve the drop resistance of the glass.

[0024] After the light scanning, there are still microcracks around the glass that are not easy to detect. During the ion exchange in the tempering process, the larger ions entering the glass will cause the microcracks on the glass to be stretched, so by the first etching process, most of the microcracks can be treated before the tempering process to prevent the cracks from continuing to expand during the ion exchange process and affecting the quality of the glass.

[0025] The glass strengthening method provided by the above embodiments can effectively improve the drop resistance, impact resistance and edge compression strength of the glass by performing the first etching treatment between the polishing and the tempering treatment, and by controlling the temperature and time range of the first tempering and the second tempering. The drop resistance is tested by the real machine drop test, which refers to that after the glass is made into a protective film and attached to the screen of an electronic device, the electronic device with the attached protective film is dropped from a certain height with the front face downward to the sandpaper, and whether the protective film is broken is used to judge the drop resistance of the glass.

[0026] For example, if the first etching treatment in the above strengthening method is omitted, the falling ball impact strength of the strengthened glass can reach 64g / 70cm (64g solid steel ball impact from 70cm height) with a pass rate of more than 90%, the average edge compression strength is about 100N, and the real machine drop test can pass at a height of 40cm. However, by using the strengthening method of the above embodiments of the present application, which performs the first etching treatment before the tempering treatment and after the polishing, the falling ball impact strength of the strengthened glass can reach 64g / 100cm with a pass rate of more than 90%, the average edge compression strength is about 150N, and the real machine drop test can pass at a height of more than 50cm.

[0027] In some embodiments, the temperature of the first tempering is 585°C-395°C, preferably 390°C; the time is 2.3-2.7 hours, preferably 2.5 hours; the temperature of the second tempering is 375°C-385°C, preferably 380°C; and the time is 0.8-1.2 hours, preferably 1 hour. The drop resistance of the glass can be further improved.

[0028] In some embodiments, the tempering further includes a third tempering, the temperature of the third tempering is 385°C-395°C, preferably 390°C; and the time is 8-12 min, preferably 10 min. The tempering salt for the third tempering is potassium nitrate, and the concentration of the potassium nitrate is more than 99.9%. The fundamental purpose of the tempering treatment is to create a strong surface compression layer on the glass surface. After the second tempering, there may still be some small ions on the glass surface that have not been completely exchanged. The high temperature environment of the third tempering can provide the last driving force for these residual ions to complete the last exchange with the surrounding ions, thereby "filling" the lattice vacancies and making the compression layer the most dense. The drop resistance of the glass can be further improved by the third tempering.

[0029] In some embodiments, the thickness of the glass thinned in the first etching treatment is in the range of 5-8 microns, which can ensure a high yield.

[0030] In some embodiments, the glass strengthening method further comprises: (5) performing a second etching treatment after the tempering, the thickness of the second etching treatment being 2-3 microns. After the tempering, the glass edge is expanded to reform micro-cracks due to the entry of larger ions in the ion exchange process, and therefore, the second etching treatment after the tempering in the present embodiment can etch away the reformed micro-cracks, and further improve the quality of the glass.

[0031] In some embodiments, a first etching treatment is further performed between the CNC edge polishing and the edging, so as to thin the glass by 7-10 microns. Through the step, most of the micro-cracks generated on the surface edge of the glass after the CNC edge polishing can be removed, and the fine scratches can be repaired by the edging, further improving the strength of the glass.

[0032] In some embodiments, the chemical etching solution used in the first etching treatment, the second etching treatment and the etching treatment between the CNC edge polishing and the edging can be the same, and comprises the following components in mass percentage: water 75%-80%, hydrofluoric acid 20%-25%. Specifically, for example, the water is 75% and the hydrofluoric acid is 25% in mass percentage.

[0033] The present embodiment further provides a strengthened glass, which is obtained by strengthening the lithium aluminum silicon glass by the aforementioned glass strengthening method, and has good drop resistance, edge compression strength and drop ball impact strength.

[0034] The present embodiment further provides a protective film comprising the aforementioned strengthened glass. Specifically, for example, after the glass is strengthened by the aforementioned glass strengthening method, the glass is further subjected to: (6) an AF (Anti-Fingerprint) plating treatment; and (7) a glue sticking treatment. The AF plating treatment specifically uses a Sankyo super smooth plating pill, and the friction coefficient is less than 0.03, so that the surface of the protective film has better anti-fingerprint / oil stain resistance and is easy to clean. The glue sticking treatment is to stick the AB glue to the strengthened glass, so that the protective film can be stuck to the screen of the electronic product through the AB glue. The protective film provided by the present embodiment uses the aforementioned strengthened glass, has better strength performance, can better protect the screen of the electronic product, and enables the user to obtain a better use experience.

[0035] The following experiments 1-10 illustrate the parameters and effects of the glass strengthening method provided in the above embodiments of the present application. The lithium aluminum silicon glass used in experiments 1-10 has a thickness of 0.33 mm. The strengthening sequence of experiment 1 is CNC corner polishing - polishing - tempering treatment. The strengthening sequence of experiment 2 is CNC corner polishing - polishing - first etching treatment - tempering treatment. The strengthening sequence of experiment 3 is CNC corner polishing - polishing - tempering treatment - thinning. The strengthening sequence of experiments 4-10 is CNC corner polishing - polishing - first etching treatment - tempering treatment - second etching treatment.

[0036] Experiment 1: The main process parameters of experiment 1 are as follows: the temperature of the first tempering is 440°C, the duration is 2H, the temperature of the second tempering is 420°C, the duration is 1.5H, there is no third tempering, and there is no thinning treatment.

[0037] Experiment 2: The main process parameters of experiment 2 are as follows: the temperature of the first tempering is 440°C, the duration is 2H, the temperature of the second tempering is 420°C, the duration is 1.5H, there is no third tempering, the glass is thinned by chemical etching before tempering by 5-8 microns, and there is no thinning treatment after tempering.

[0038] Experiment 3: The main process parameters of experiment 3 are as follows: the temperature of the first tempering is 440°C, the duration is 2H, the temperature of the second tempering is 420°C, the duration is 1.5H, there is no third tempering, there is no thinning treatment before tempering, and the glass is thinned by chemical etching after tempering by 2-3 microns.

[0039] Experiment 4: The main process parameters of experiment 4 are as follows: the temperature of the first tempering is 440°C, the duration is 2H, the temperature of the second tempering is 420°C, the duration is 1.5H, there is no third tempering, the glass is thinned by the first etching treatment before tempering by 5-8 microns, and the glass is thinned by the second etching treatment after tempering by 2-3 microns.

[0040] Experiment 5: The main process parameters of experiment 5 are as follows: the temperature of the first tempering is 390°C, the duration is 2.5H, the temperature of the second tempering is 380°C, the duration is 1.5H, there is no third tempering, the glass is thinned by the first etching treatment before tempering by 5-8 microns, and the glass is thinned by the second etching treatment after tempering by 2-3 microns.

[0041] Experiment 6: The main process parameters of Experiment 6 are as follows: the temperature of the first tempering is 390°C, the time is 1.5H, the temperature of the second tempering is 380°C, the time is 1H, there is no third tempering, the first etching treatment is used to thin 5-8 microns before tempering, and the second etching treatment is used to thin 2-3 microns after tempering.

[0042] Experiment 7: The main process parameters of Experiment 7 are as follows: the temperature of the first tempering is 390°C, the time is 1.5H, the temperature of the second tempering is 380°C, the time is 1.5H, there is no third tempering, the first etching treatment is used to thin 5-8 microns before tempering, and the second etching treatment is used to thin 2-3 microns after tempering.

[0043] Experiment 8: The main process parameters of Experiment 8 are as follows: the temperature of the first tempering is 390°C, the time is 2.5H, the temperature of the second tempering is 380°C, the time is 1H, there is no third tempering, the first etching treatment is used to thin 5-8 microns before tempering, and the second etching treatment is used to thin 2-3 microns after tempering.

[0044] Experiments 9 and 10: The main process parameters of Experiments 9 and 10 are as follows: the temperature of the first tempering is 390°C, the time is 2.5H, the temperature of the second tempering is 380°C, the time is 1H, the temperature of the third tempering is 390°C, the time is 10min, the first etching treatment is used to thin 5-8 microns before tempering, and the second etching treatment is used to thin 2-3 microns after tempering.

[0045] The main relevant parameters of Experiments 1 to 10 are shown in Table 1.

[0046] Table 1:

[0047] The strengthened glasses obtained in Experiments 1-10 were respectively subjected to edge pressure test, ball drop test and real machine drop test. The ball drop test is 64g / 200cm solid 3 times (64g solid steel ball is dropped from a height of 200cm to complete 3 impacts), and the real machine drop test is to paste the protective film made of the strengthened glass on the iPhone 16pro with the front of the phone facing down and drop it from different heights onto the surface above the 320 mesh sandpaper. The average edge pressure value and the ball drop test pass rate experimental results are shown in Table 2. The real machine drop test experimental results are shown in Table 3, PASS means pass, and NG means fail.

[0048] Table 2:

[0049] Table 3 (5 samples of strengthened glass for each experiment were tested, and the samples of each height PASS were tested for the next height)

[0050] According to Tables 2 and 3, in the experiment 1, no thinning treatment is performed, only two times of tempering are performed, the average edge pressure value and the drop ball test result are both low, and the maximum drop test that can be passed is 40 cm. In the experiment 2, an etching treatment is performed between the light scanning and the tempering treatment, the average edge pressure value, the drop ball test passing rate and the drop test result are all better than those in the experiment 1, and the maximum drop test that can be passed is 60 cm. In the experiment 3, only one etching treatment is performed after the tempering treatment, the average edge pressure value, the drop ball test passing rate and the drop test result are all better than those in the experiment 1, and the maximum drop test that can be passed is 70 cm, but the passing rate of the 40 cm drop test is lower than that in the experiment 2. In the experiment 4, the first etching treatment and the second etching treatment are performed before and after the tempering treatment, respectively, the average edge pressure value and the drop ball test passing rate are higher than those in the experiment 3, and the drop test result is basically the same as that in the experiment 3. In the experiments 5-8, the temperature and the time of the first tempering and the second tempering are adjusted, and the average edge pressure strength, the drop ball test passing rate and the real machine drop test result are all improved. In the experiments 9 and 10, the third tempering is added, the drop test result is further improved compared with the experiments 5-8, and the average edge pressure value is also improved.

[0051] According to the comparison of the above experimental results, it can be known that the glass strengthening method provided in the above embodiments can improve the glass strength and effectively improve the product quality by performing the first etching treatment before the tempering treatment to process part of the glass surface micro-cracks to improve the glass strength, performing the second etching treatment after the tempering treatment, and performing multiple tempering with specific temperature and time range to improve the drop resistance and the drop ball impact resistance of the glass.

[0052] In addition, it can be understood that the foregoing embodiments are only exemplary descriptions of the present application, and the technical solutions of the embodiments can be arbitrarily combined and used without conflict in technical features, contradiction in structure and deviation from the purpose of the present application.

[0053] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A glass strengthening method characterized by, The glass is lithium aluminum silicon glass, and the glass strengthening method comprises the following steps: (1) performing CNC corner polishing on the cut glass; (2) performing polishing after the CNC corner polishing to polish the surface of the glass; (3) performing first etching treatment after the polishing; (4) performing tempering treatment after the first etching treatment to make the glass ion exchange with a tempering salt, the tempering treatment comprising first tempering and second tempering, the temperature of the first tempering being 380-440 DEG C, and the time being 1.5-3 hours; the temperature of the second tempering being 370-420 DEG C, and the time being 0.5-1.5 hours.

2. The glass strengthening method of claim 1, wherein, The temperature of the first tempering is 385-395 DEG C, and the time is 2.3-2.7 hours; the temperature of the second tempering is 375-385 DEG C, and the time is 0.8-1.2 hours.

3. The glass strengthening method of claim 1, wherein, The tempering treatment further comprises third tempering, the temperature of the third tempering being 385-395 DEG C, and the time being 8-12 min.

4. The glass strengthening method of claim 1, wherein, The tempering salt used in the first tempering is a mixture of 45-55% potassium nitrate and 45-55% sodium nitrate by mass percentage; the tempering salt used in the second tempering is a mixture of 92-98% potassium nitrate and 2-8% sodium nitrate by mass percentage.

5. The glass strengthening method according to claim 1, wherein, The thickness of the glass is thinned by 5-8 microns in the first etching treatment.

6. The glass strengthening method of claim 1, wherein, The glass strengthening method further comprises (5) performing second etching treatment after the tempering treatment, the thickness of the second etching treatment being 2-3 microns.

7. The glass strengthening method according to claim 1, wherein, The glass strengthening method further comprises performing etching treatment between the CNC corner polishing and the polishing to thin the glass by 7-10 microns.

8. The glass strengthening method of claim 1, wherein, The etching liquid in the first etching treatment comprises the following components by mass percentage: water 75-80%, hydrofluoric acid 20-25%.

9. A strengthened glass characterized by, The strengthened glass is obtained by strengthening the lithium aluminum silicon glass by the glass strengthening method according to any one of claims 1-8.

10. A protective film characterized by comprising: The strengthened glass according to claim 9.

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