Preparation process of unequal-thickness flexible glass and unequal-thickness flexible glass prepared by preparation process

Abstract

The invention discloses a preparation process of unequal-thickness flexible glass and the unequal-thickness flexible glass prepared by the preparation process. Compared with an existing flexible glass preparation technology, the preparation method has the advantages that technical innovation is carried out on a plurality of procedures according to the particularity of the flexible glass with different thicknesses, and a brand-new preparation technology is formed. A raw material glass substrate with an optimized material formula is adopted, so that the mechanical property of the glass is enhanced. And a Vickers hardness machining platform in a specific range is used, and grooving is performed through a cold carving process, so that the thickness uniformity of the unequal-thickness part is improved. Through the improved thinning and chamfering processing technology, the bending performance of the glass is enhanced. A secondary chemical tempering mode is adopted, differential partition tempering is carried out, and a tempering alkali salt formula is optimized, so that the unequal-thickness part is free of wrinkles, and the equal-thickness part is high in impact resistance. And through precisely-controlled micro-thinning treatment, low surface defects, no appearance warping and high strength performance are achieved. The unequal-thickness flexible glass produced by adopting the process has the characteristics of being good in appearance, excellent in bending performance and high in impact resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible glass, and in particular relates to a preparation process for unequal-thickness flexible glass and unequal-thickness flexible glass prepared by this preparation process. Background Art

[0002] Ultra-thin flexible glass (UTG) refers to a glass material with bendable properties and a thickness less than 0.1 mm in the bending area. Compared with ordinary glass materials, UTG has good flexibility and plasticity, combining the advantages of glass and plastic, and has great application value. With the continuous progress of technology and the continuous expansion of applications, UTG is gradually emerging in application scenarios such as consumer electronics, semiconductors, photovoltaics, automobiles, and medical treatment, and is most widely used in the flexible display field of consumer electronics. As a screen cover plate material, UTG can better solve common problems of polyimide (CPI) screens such as insufficient flatness, obvious creases, and light and shadow distortion.

[0003] Although UTG has many advantages, due to its extremely thin thickness, its impact resistance is poor. Therefore, it is necessary to increase the thickness to improve the impact resistance of UTG. However, the increase in thickness will lead to a decrease in the bending performance of UTG. To solve the above problems, the current method is to design an unequal-thickness structure for the glass substrate, so that the thickness of the glass layer in the non-bending area, that is, the equal-thickness part, is larger, and the thickness of the glass layer in the bending area, that is, the unequal-thickness part, is smaller. The above design takes into account the impact resistance of the equal-thickness part and the bending performance of the unequal-thickness part.

[0004] However, the above unequal-thickness structure design brings new challenges to actual production. The preparation methods for the unequal-thickness part are mainly divided into wet etching process and cold carving process. The wet etching process uses a zoning etching method or a bending immersion etching method to make the thickness transition area of the unequal-thickness part, that is, the thickness on both sides of the groove gradually decreases. Among them, when using the zoning etching method to prepare the unequal-thickness part, there is a problem that the two sides of the groove are in the shape of "micro-steps", and the thickness uniformity of the unequal-thickness part is poor due to multiple etching processes, affecting the bending performance of the unequal-thickness flexible glass; while the bending immersion etching method has strict restrictions on the thickness of the glass substrate, and when the glass substrate is thick, it cannot be bent, resulting in a lower upper limit for the impact resistance of the equal-thickness part of the unequal-thickness flexible glass. The cold carving process is to use a high-precision grinding head to perform profiling processing on the surface of the glass substrate, which can accurately control the shape, depth, and slope of the unequal-thickness part, but it is easy to cause poor thickness uniformity of the unequal-thickness part. This not only causes a decrease in the bending performance of the unequal-thickness flexible glass, but also easily causes problems in the downstream of the industrial chain, including the bonding with other components, the preparation of the screen module, and the preparation process of the terminal product.

[0005] Meanwhile, there are also new problems in the tempering process of the post-process of flexible glass with unequal thickness. Due to the thickness difference in different regions of the flexible glass with unequal thickness, after chemical tempering, the tempering expansion degrees of regions with different thicknesses are different, resulting in the appearance of wrinkles on the surface of the unequal-thickness part and causing stress concentration in the unequal-thickness part, which is prone to breakage during bending.

[0006] Therefore, how to prepare flexible glass with unequal thickness that has excellent appearance and performance indicators is an important technical problem that urgently needs to be solved. Summary of the Invention

[0007] In order to solve the problems existing in the prior art, the inventor team of the present invention has carried out technological innovations on multiple processes in the preparation process of flexible glass with unequal thickness through long-term research, and finally achieved a breakthrough in the preparation process of flexible glass with unequal thickness. Using the preparation process described in the present invention, flexible glass with unequal thickness having excellent appearance without wrinkles, excellent bending performance and strength performance can be prepared. This process provides a solution for improving the service life of ultra-thin flexible glass and lays a foundation for the application and popularization of ultra-thin flexible glass in flexible display, semiconductor, photovoltaic, automotive, and medical fields.

[0008] The present invention provides a preparation process for flexible glass with unequal thickness. The preparation process includes the following processes:

[0009] Raw material selection: Select a high strain point aluminosilicate ultra-thin glass substrate as the processing raw material;

[0010] Grooving: Place the glass substrate on a processing platform with a Vickers hardness range of 150 Kgf / mm 2 ~550 Kgf / mm 2 and use a cold carving process to process grooves to form a glass substrate with an unequal-thickness part;

[0011] Etching: Etch and thin the glass substrate with an unequal-thickness part to form flexible glass with unequal thickness;

[0012] Protection treatment: Form a protective layer on the first and second surfaces of the flexible glass with unequal thickness;

[0013] Cutting: Cut the flexible glass with unequal thickness to form a preset shape and size;

[0014] Edge treatment: Perform edge treatment on the flexible glass with unequal thickness to produce a chamfer at its edge;

[0015] Chemical tempering: Perform secondary tempering on the flexible glass with unequal thickness to improve its strength performance;

[0016] Pickling: Perform pickling and slight thinning on the flexible glass with unequal thickness to release stress and repair its surface micro-defects.

[0017] Among them, in the raw material selection process, preferably, the glass substrate material can be aluminosilicate glass, borosilicate glass, phosphosilicate glass or glass-ceramics. In order to achieve the best performance of the unequal-thickness flexible glass, high-strain-point aluminosilicate glass is further preferred to improve the chemical stability, elastic modulus and hardness of the glass substrate, thereby enhancing its overall mechanical properties.

[0018] In the grooving process, preferably, a cold carving process is used to groove the surface of the glass substrate. The thickness of the preset unequal-thickness part is reduced by physical ablation using a high-precision numerical control machine tool and a high-precision cold carving grinding head, and then the surface of the glass substrate is polished to enhance its light transmittance. In this process, the morphology of the unequal-thickness part can be controlled by designing the shape of the grinding head; a processing platform with a Vickers hardness in the range of 150Kgf / mm 2 ~550Kgf / mm 2 is used to ensure that the unequal-thickness part has excellent thickness uniformity. The unequal-thickness part can be distributed at any position on the upper and lower surfaces of the glass substrate, and its quantity can be determined according to specific requirements.

[0019] In the etching process, preferably, the overall thickness of the glass substrate with unequal-thickness parts is thinned to form unequal-thickness flexible glass. Before etching and thinning, the surface of the area of the glass substrate that does not need to be thinned can be coated with a film or a coating for acid-resistant protection according to the quantity and position of the unequal-thickness parts, and the protective layer is removed after etching and thinning. The immersion etching method, the waterfall flow etching method or the spray etching method can be used, and preferably the spray etching method is adopted.

[0020] In the protection treatment process, preferably, an acid-resistant organic material is coated or screen-printed on the first and second surfaces of the unequal-thickness flexible glass, and after curing, an acid-resistant protective layer is formed to improve the damage resistance of the unequal-thickness flexible glass during the cutting process and reduce the risk of chipping at its edges.

[0021] In the cutting process, preferably, the unequal-thickness flexible glass is cut to achieve the target shape and size. The cutting can adopt the cutting wheel cutting method, the grinding wheel cutting method, the laser cutting method or a combination of the above methods, and preferably the laser cutting method is adopted to reduce the degree of edge breakage of the unequal-thickness flexible glass.

[0022] In the edge treatment process, preferably, the unequal-thickness flexible glass is chamfered to reduce the degree of edge stress concentration and improve the durability and bending ability of the unequal-thickness flexible glass. The chamfering process can adopt the laser processing method, the acid etching method, the mechanical cold processing method, the fire polishing method or a combination of the above methods, and preferably the acid etching method is adopted to avoid microcracks at the edges caused by mechanical processing and at the same time repair the edge defects caused by cutting.

[0023] In the chemical toughening process of the steel chemical process, preferably, the unequal-thickness flexible glass is chemically toughened by a secondary toughening method. In the secondary toughening, the regions of the first and second toughening and the used toughening alkali salt formulations are respectively optimized. In the first step, the whole of the unequal-thickness flexible glass is chemically toughened, and a mixed salt of potassium nitrate and sodium nitrate is selected as the toughening alkali salt. By reducing the degree of potassium and sodium ion exchange, the toughening expansion difference caused by the thickness difference of the unequal-thickness flexible glass is alleviated, and the generation of wrinkles in the unequal-thickness part is avoided. In the second step, after high-temperature resistant protective layers are provided on the upper and lower surfaces of the unequal-thickness part, the equal-thickness part of the unequal-thickness flexible glass is chemically toughened again, and a mixture of potassium nitrate and a toughening catalyst is selected as the toughening alkali salt for catalytic toughening to further improve the strength performance of the equal-thickness part of the unequal-thickness flexible glass. Preferably, the toughening catalyst is selected from one or more of potassium hydroxide, potassium chloride, potassium sulfate, and potassium phosphate.

[0024] In the pickling process, preferably, the unequal-thickness flexible glass is pickled and slightly thinned. The whole of the unequal-thickness flexible glass is placed in a mixed acid solution for pickling and slight thinning to repair the surface microcrack defects and release part of the compressive stress formed after chemical toughening, so as to further improve the strength and bending performance of the unequal-thickness flexible glass.

[0025] Preferably, after the above treatment, the surface compressive stress value CS of the unequal-thickness flexible glass is not less than 400 MPa, and the depth DoL of the compressive stress layer is not less than 5 μm.

[0026] At the same time, the present invention provides an unequal-thickness flexible glass prepared according to the above preparation process, including: at least one unequal-thickness part located on the first surface or the second surface, at least one equal-thickness part located on the first surface or the second surface, the glass thickness of the unequal-thickness part is less than the glass thickness of the equal-thickness part, the total thickness variation TTV of each part of the glass ≤ 6 μm, the compressive stress CS of the unequal-thickness flexible glass is at least 400 MPa, and the depth DoL of the compressive stress layer is at least 5 μm.

[0027] Among them, the total thickness variation TTV is used to characterize the thickness uniformity of the glass in a certain area, which is the difference between the actual maximum thickness and the minimum thickness in the measurement area. For the unequal-thickness flexible glass, the TTV of the equal-thickness part is used to characterize the thickness uniformity of the glass in the equal-thickness part, and the measurement area is the area of the equal-thickness part. The TTV of the unequal-thickness part is used to characterize the thickness uniformity of the glass in the unequal-thickness part, and its measurement area is the area of the minimum preset thickness of the unequal-thickness part.

[0028] Beneficial effects:

[0029] By innovating and optimizing the preparation process of the flexible glass with unequal thicknesses, the present invention reduces the surface defects of the flexible glass with unequal thicknesses, improves the thickness uniformity of the unequal-thickness part, reduces the degree of local stress concentration when the unequal-thickness part is bent, ensures its bending performance, improves the impact resistance of the equal-thickness part, and extends the service life of the flexible glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the overall flow chart of the preparation process of the flexible glass with unequal thicknesses;

[0031] Figure 2 is the cross-sectional schematic diagram of the flexible glass with unequal thicknesses;

[0032] Figure 3-1 is the cross-sectional schematic diagram of a morphologically unequal-thickness part

[0033] Figure 3-2 is Figure 3-1 the top view schematic diagram corresponding to the cross-sectional schematic diagram of a morphologically unequal-thickness part described;

[0034] Figure 4-1 is the cross-sectional schematic diagram of another morphologically unequal thickness;

[0035] Figure 4-2 is Figure 4-1 the top view schematic diagram corresponding to the cross-sectional schematic diagram of another morphologically unequal thickness described;

[0036] Figure 5 is the schematic diagram of the preparation process of the flexible glass with unequal thicknesses. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] Hereinafter, the technical solutions of the present invention will be described in detail with reference to the drawings.

[0038] Specifically, the present invention provides a method for preparing a flexible glass with unequal thicknesses. As Figure 1 shown, the preparation method includes the following processes:

[0039] Raw material selection: Select a high strain point aluminosilicate ultra-thin glass substrate as the processing raw material;

[0040] Grooving: Place the glass substrate on a processing platform with a Vickers hardness range of 150 Kgf / mm 2 ~550 Kgf / mm 2 and use a cold carving process to process grooves to form a glass substrate with an unequal-thickness part;

[0041] Etching: Etch and thin the glass substrate with an unequal-thickness part to form a flexible glass with unequal thicknesses;

[0042] Protection treatment: Form a protective layer on the first and second surfaces of the flexible glass with unequal thicknesses;

[0043] Cutting: Cut the flexible glass with unequal thickness to form a preset shape and size;

[0044] Edge treatment: Perform edge treatment on the flexible glass with unequal thickness to produce a chamfer on its edge;

[0045] Chemical toughening: Perform secondary toughening on the flexible glass with unequal thickness to improve its strength performance;

[0046] Pickling: Perform pickling and slight thinning on the flexible glass with unequal thickness to release stress and repair its surface micro-defects.

[0047] As Figure 2 shown, the present invention provides a flexible glass (9) with unequal thickness, including: an equal-thickness part (7), and an unequal-thickness part (8) formed by a groove, wherein the unequal-thickness part (8) is at least one.

[0048] A first surface (5) jointly constituted by the upper surface (1) of the equal-thickness part and the upper surface (3) of the unequal-thickness part, and a second surface (6) jointly constituted by the lower surface (2) of the equal-thickness part and the lower surface (4) of the unequal-thickness part.

[0049] The glass thickness T' of the unequal-thickness part (8) is less than the thickness T of the equal-thickness part (7), and the total thickness variation TTV of each part of the glass ≤ 6 μm.

[0050] As shown in FIGS. 3 and 4, the total thickness variation TTV is the difference between the actual maximum thickness and the minimum thickness in the measurement area. For the flexible glass (9) with unequal thickness, the TTV of the equal-thickness part is used to characterize the thickness uniformity of the glass in the equal-thickness part, and the measurement area is the area (7) of the equal-thickness part. The TTV of the unequal-thickness part is used to characterize the thickness uniformity of the glass in the unequal-thickness part, and its measurement area is the area (10, 11) with the minimum preset thickness in the unequal-thickness part (8).

[0051] As Figure 5 shown, the preparation process is described in the form of a process flow chart. Next, each process will be elaborated in detail.

[0052] Raw material selection: Preferably, to meet the performance requirements of the flexible glass with unequal thicknesses, the glass raw materials used in the present invention include, but are not limited to, aluminosilicate glass, borosilicate glass, phosphosilicate glass, and glass-ceramics. More preferably, the present invention selects a high strain point aluminosilicate glass with the following batch formula ratio: 55% - 75% of SiO2, 5% - 22% of Al2O3, 3% - 10% of K2O, 1% - 15% of Na2O, 0% - 5% of CaO, 0% - 5% of SnO2, 0% - 5% of ZnO, 0% - 5% of MgO, 0% - 3% of TiO2, 0.3% - 3% of ZrO2, 0% - 8% of La2O3, and 0.1% - 0.5% of CeO2. Compared with the conventional aluminosilicate glass composition, this batch formula makes the glass structure more compact, enhances the mechanical strength of the glass, improves the impact resistance of the glass, and also reduces the influence of alkali metal ions on the glass structure, improves the chemical stability of the glass, increases the transmittance of the glass and reduces its light scattering.

[0053] Grooving: Preferably, a cold engraving process is used to perform profiling on the first and second surfaces of the glass substrate on the processing platform to form an unequal thickness portion. The Vickers hardness range of the processing platform is preferably 150 Kgf / mm 2 - 550 Kgf / mm 2 , more preferably 200 Kgf / mm 2 - 450 Kgf / mm 2 , still more preferably 250 Kgf / mm 2 - 400 Kgf / mm 2 ; even more preferably 300 Kgf / mm 2 - 350 Kgf / mm 2 .

[0054] In previous actual production, the inventor found that when grooving the surface of the glass substrate using the cold engraving process, the thickness uniformity of the unequal thickness portion is poor. Especially as the thickness of the unequal thickness portion decreases, the TTV value increases significantly, reaching 15 μm - 20 μm.

[0055] The inventor discovered through a large amount of research the deep relationship between the hardness of the cold engraving process processing platform and the processing quality: A platform with a Vickers hardness ≤ 150 Kgf / mm 2 has difficulty providing sufficient support force for the glass substrate and cannot ensure the flatness of the processed surface. A platform with a Vickers hardness ≥ 550 Kgf / mm 2 will significantly increase the risk of glass scratching and breakage. The Vickers hardness is maintained at 150 Kgf / mm 2 - 550 Kgf / mm 2Within a certain range, a better cold engraving effect can be achieved. By using the grooving process of the present invention, the processing accuracy of the shape, depth, and slope of the unequal thickness part can be significantly improved, the TTV of the unequal thickness part can be reduced, and at the same time, the original thickness of the glass substrate and the final thickness of the unequal thickness flexible glass product are not restricted. It has the characteristics of a wide application range and excellent thickness performance, and has more advantages than other processes.

[0056] The surface of the unequal thickness part formed by the cold engraving process usually presents a matte texture. In order to improve the light transmittance of these areas, a polishing treatment is preferably carried out.

[0057] Etching: As a preference, in order to achieve the target thickness of the finished product, the glass substrate with an unequal thickness part needs to be chemically etched and thinned. The immersion etching method, waterfall flow etching method, and spray etching method can be used, and the spray etching method is preferably used. Before etching and thinning, in order to protect the area that does not need to be thinned, a protective treatment such as covering an acid-resistant film or coating ink can be carried out on this area.

[0058] The main components of the thinning solution used for chemical etching and thinning may include, but are not limited to, hydrofluoric acid, hydrochloric acid, sulfuric acid, fluorosilicic acid, nitric acid, ammonium bifluoride, and sodium fluorosilicate. In order to optimize the etching effect, it is preferred to use etching solution A and etching solution B for etching respectively. After etching, a calcium and magnesium ion mixed solution is used for surface modification, and then a hydrophobic repair solution is used for surface treatment. The etching solution A uses deionized water as a solvent and includes the following molar concentration components: hydrofluoric acid 1.5 mol / L to 3 mol / L, hydrochloric acid 0.5 mol / L to 1.5 mol / L, sodium fluorosilicate 1.0 mol / L to 1.5 mol / L, sodium dodecyl sulfate 0.1 mol / L to 0.2 mol / L. The etching solution B uses deionized water as a solvent and includes the following molar concentration components: hydrofluoric acid 0.5 mol / L to 1.5 mol / L, hydrochloric acid 0.3 mol / L to 0.8 mol / L, sodium fluorosilicate 0.5 mol / L to 0.8 mol / L, sodium dodecyl sulfate 0.1 mol / L to 0.2 mol / L. The calcium and magnesium ion mixed solution uses deionized water as a solvent and includes the following molar concentration components: calcium chloride 0.05 mol / L to 0.2 mol / L, magnesium chloride 0.05 mol / L to 0.2 mol / L. The hydrophobic repair solution includes the following mass fraction components: aqueous fluorocarbon emulsion 40 parts to 50 parts, hydrophobic agent 1 part to 3 parts, sodium silicate 5 parts to 7 parts, sodium fluoride 2 parts to 3 parts, nano-titanium oxide sol 10 parts to 15 parts, nano-silicon oxide sol 15 parts to 20 parts, mixed solution of cetyltrimethylammonium bromide and polyepoxysuccinic acid sodium 3 parts to 5 parts, amino-silane coupling agent 1 part to 2 parts, emulsifier 0.5 part to 2 parts. By using the above combination of etching solutions and repair solutions, the defects on the surface of the glass substrate can be repaired after etching, thereby improving the structural stability and mechanical strength, and at the same time endowing the glass with flexibility and preventing it from cracking.

[0059] Protection treatment: Preferably, after the etching process, an acid-resistant organic material is applied to the first and second surfaces of the flexible glass with unequal thicknesses by coating methods such as scraping, roller coating, spraying, or spin coating, or by screen printing, and after curing, the organic material forms a protective layer, reducing the risk of edge chipping of the flexible glass with unequal thicknesses in the subsequent cutting process, and at the same time providing favorable conditions for the chamfering process.

[0060] Cutting: Preferably, through the cutting process, the flexible glass with unequal thicknesses with a protective layer is processed to the required size and preset shape. The cutting can adopt a wheel cutting method, a grinding wheel cutting method, a laser cutting method, or a combination of the above methods, and preferably a laser cutting method is adopted to reduce the risk of glass breakage and edge chipping, and the processed edge has a neater effect.

[0061] Edge treatment: Preferably, the edge morphology of the cut flexible glass with unequal thicknesses is processed to form a chamfer. A laser processing method, an acid etching method, a mechanical cold processing method, a flame polishing method, or a combination of the above methods can be adopted, and preferably an acid etching method is adopted. After forming the chamfer, the flexible glass with unequal thicknesses with a protective layer is soaked in an organic solvent for a period of time to remove the protective layer. Preferably, the organic solvent includes one or more of toluene, xylene, acetone, ethyl acetate, chloroform, and styrene.

[0062] Chemical tempering: Preferably, a secondary tempering method is used to chemically temper the flexible glass with unequal thicknesses.

[0063] The tempering alkali salt used for the first tempering is a mixed salt of solid potassium nitrate and sodium nitrate, and the mass ratio range of sodium nitrate to potassium nitrate is preferably 1:9 to 2:11, more preferably 1:8 to 3:17, and even more preferably 1:7 to 1:6;

[0064] The process of the first tempering includes: after cleaning the flexible glass with unequal thicknesses, preheating it at 350°C to 400°C for 20 min to 40 min, and then transferring it to a salt bath furnace containing a mixed salt of solid potassium nitrate and sodium nitrate for tempering. The tempering temperature is preferably 370°C to 420°C, more preferably 380°C to 410°C, and even more preferably 390°C to 400°C. The tempering time is preferably 5 min to 30 min, more preferably 10 min to 25 min, and even more preferably 15 min to 20 min. After the chemical tempering is completed, the flexible glass with unequal thicknesses is transferred to a water bath at 40°C to 60°C to rapidly cool down, thereby completing the first tempering treatment.

[0065] During the tempering process of glass materials, potassium ions in the tempering alkali salt replace sodium ions in the glass. After experiencing thermal expansion and then rapid cooling, the potassium ions that enter the glass surface occupy more space due to their larger volume, causing the surface layer of the glass to expand. However, the un-replaced glass part in the lower layer restricts its free expansion, thus forming a compressive stress layer on the surface and causing an increase in the size of the tempered glass material. This phenomenon is called tempering expansion.

[0066] For flexible glass with unequal thickness, due to the larger tempering expansion rate in the thinner area and the smaller tempering expansion rate in the thicker area, the flexible glass with unequal thickness is prone to form wrinkles. In the present invention, by using a mixed salt of sodium nitrate and potassium nitrate as the tempering alkali salt, the concentration difference of potassium and sodium ions on the glass surface can be reduced, the degree of ion exchange can be decreased, and the surface wrinkle problem caused by the inward extrusion stress in the thin area due to different tempering expansion rates can be alleviated.

[0067] The tempering alkali salt used in the second tempering is a mixture of solid potassium nitrate and a tempering catalyst. Among them, the tempering catalyst is one or more of potassium hydroxide, potassium chloride, potassium sulfate, and potassium phosphate. The molar ratio range of potassium ions in potassium nitrate to potassium ions in the tempering catalyst is preferably 30:1 to 10:1, more preferably 27:1 to 13:1, and even more preferably 23:1 to 17:1;

[0068] The process of the second tempering includes: setting high-temperature resistant protective layers on the upper and lower surfaces of the unequal-thickness part of the flexible glass with unequal thickness, preheating the flexible glass with unequal thickness at 350°C to 400°C for 20 min to 40 min, and then transferring it to a salt furnace containing solid potassium nitrate and a tempering catalyst. The tempering temperature is preferably 370°C to 420°C, more preferably 380°C to 410°C, and even more preferably 390°C to 400°C. The tempering time is preferably 5 min to 30 min, more preferably 10 min to 25 min, and even more preferably 15 min to 20 min. After the chemical tempering is completed, transfer the flexible glass with unequal thickness to a water bath at 40°C to 60°C for rapid cooling, and remove the high-temperature resistant protective layer on the glass surface after taking out the glass to complete the second tempering treatment.

[0069] The combination of the anions in the tempering catalyst and the hydroxyl groups on the glass surface reduces the diffusion activation energy of potassium ions, and at the same time breaks the silicon-oxygen network structure to open up new ion exchange channels, thereby increasing the exchange quantity of potassium and sodium ions. The negatively charged anions in the tempering catalyst usually have a large polarity, and the resulting changes in the electric field and charge distribution further promote the outward migration of sodium ions and accelerate the ion exchange process. By adding the tempering catalyst, the exchange degree of potassium and sodium ions in the second tempering is improved, and the strength performance of the equal-thickness part of the flexible glass with unequal thickness is enhanced.

[0070] Acid pickling: Preferably, the tempered flexible glass with unequal thicknesses is subjected to acid pickling and micro-thinning. The whole is placed in a mixed acid solution for acid pickling and micro-thinning. The preferred thinning thickness range is 1 μm to 2 μm, more preferably 1.2 μm to 1.8 μm, and even more preferably 1.4 μm to 1.6 μm, so as to repair the micro-cracks on the surface of the flexible glass with unequal thicknesses and further improve the strength of the flexible glass with unequal thicknesses.

[0071] Preferably, the above-mentioned mixed acid solution includes one or more of hydrofluoric acid, hydrochloric acid, sulfuric acid, fluosilicic acid, nitric acid, ammonium bifluoride, sodium fluorosilicate, and surfactant.

[0072] In addition, the inventor found that the flexible glass with unequal thicknesses will warp after chemical tempering. Through in-depth research, the inventor found that the reason for the warping is that the original glass substrate produced by the float process includes a side in contact with tin and a side in contact with air. The tin ions existing on the side in contact with tin hinder ion exchange, resulting in a smaller degree of tempering during tempering. Due to the different degrees of tempering on the first and second surfaces of the flexible glass with unequal thicknesses, it causes warping. For the technical solution of the present invention, during the second tempering, due to the use of a tempering alkali salt added with a tempering catalyst, the improvement of the potassium and sodium ion exchange degree makes this warping phenomenon more obvious. In this regard, by adopting the acid pickling and micro-thinning process of the present invention, part of the compressive stress can be released, effectively reducing the warping degree of the flexible glass with unequal thicknesses.

[0073] It should be noted that implementing the present invention does not require simultaneously adopting all the above-mentioned preferred methods or achieving all the above-mentioned advantages.

[0074] Examples

[0075] Example 1

[0076] Select high-strain-point aluminosilicate glass as the glass original sheet. Use a processing platform with a platform Vickers hardness of 200 Kgf / mm 2 to perform cold engraving processing on the glass substrate to form an unequal-thickness part on the surface of the glass substrate. The width of the unequal-thickness part is 35 mm and the depth is 172.4 μm. The unequal-thickness part is located in the middle of the glass. After the unequal-thickness part is prepared, polish the surface of the glass substrate with the unequal-thickness part with a polishing liquid mainly composed of rare earth cerium oxide.

[0077] Cover one side of the glass with the unequal-thickness part with a PO acid-resistant UV reducing film, and use the spray etching process to etch and thin the other surface of the glass. After the etching and thinning are completed, remove the PO acid-resistant UV reducing film. After the etching and thinning, the thickness of the unequal-thickness part is 33.1 μm, and the thickness of the equal-thickness part is 205.6 μm;

[0078] Use resin-based acid-resistant materials to form protective layers on the first and second surfaces of the flexible glass with unequal thicknesses. Cut the four edges of the glass using a laser cutting machine to remove the defective areas at the four edges of the etched glass. Then, soak the flexible glass with unequal thicknesses and acid-resistant protective layers in a mixed acid solution, and then place it in an organic solvent for soaking after cleaning to obtain flexible glass with unequal thicknesses without the protective layer.

[0079] Perform the first tempering on the flexible glass with unequal thicknesses. Preheat the flexible glass with unequal thicknesses at 380 °C for 40 min, and then transfer it to a salt furnace containing solid potassium nitrate and sodium nitrate, where the mass ratio of sodium nitrate to potassium nitrate is 1:7. Chemically temper it at 400 °C for 15 min. After the chemical tempering is completed, transfer the flexible glass with unequal thicknesses to a water bath at 55 °C for rapid cooling to complete the first tempering process. Subsequently, perform the second tempering on the flexible glass with unequal thicknesses. Set high-temperature resistant protective layers on the upper and lower surfaces of the unequal thickness part of the flexible glass with unequal thicknesses. Preheat the flexible glass with unequal thicknesses at 380 °C for 40 min, and then transfer it to a salt furnace containing solid potassium nitrate and a tempering catalyst. Chemically temper it at 420 °C for 10 min. The tempering catalyst is a mixture of potassium hydroxide and potassium chloride, and the molar ratio of potassium ions in potassium nitrate to potassium ions in the tempering catalyst is 10:1. After the chemical tempering is completed, transfer the flexible glass with unequal thicknesses to a water bath at 55 °C for rapid cooling. After taking out the glass, remove the high-temperature resistant protective layer on the glass surface to complete the second tempering process.

[0080] Place the flexible glass with unequal thicknesses after chemical tempering, cleaning, and drying as a whole in a mixed acid solution for pickling and micro-thinning, with a thinning thickness of 1.9 μm. Among them, the temperature during the pickling process is controlled at 25 °C, and the pickling thinning rate is 1.3 μm / min.

[0081] After the above treatment, the minimum thickness of the unequal thickness part of the obtained flexible glass with unequal thicknesses is 31.2 μm, the compression stress value CS is 436 MPa, and the depth of the compression stress layer DOL is 6.3 μm; the maximum thickness of the equal thickness part is 203.7 μm, the compression stress value CS is 535 MPa, and the depth of the compression stress layer DOL is 6.5 μm.

[0082] Example 2

[0083] Select high-strain-point aluminosilicate glass as the glass substrate. Use a processing platform with a platform Vickers hardness of 300 Kgf / mm 2 to perform cold engraving processing on the glass substrate to form an unequal thickness part on the surface of the glass substrate. The width of the unequal thickness part is 40 mm, and the depth is 43.1 μm. The unequal thickness part is located in the middle of the glass. After the unequal thickness part is prepared, polish the surface of the glass substrate with the unequal thickness part using a polishing liquid with rare earth cerium oxide as the main component.

[0084] Cover one side of the glass with unequal thickness parts with a PO acid-resistant UV-reducing film, and use a spray etching process to etch and thin the other surface of the glass. After the etching and thinning are completed, remove the PO acid-resistant UV-reducing film. After etching and thinning, the thickness of the unequal thickness part is 33.4 μm, and the thickness of the equal thickness part is 76.5 μm;

[0085] Use a resin-based acid-resistant material to form a protective layer on the first and second surfaces of the flexible glass with unequal thickness. Use a laser cutting machine to cut the four edges of the glass, remove the defective areas at the four edges of the etched glass, and then soak the flexible glass with unequal thickness with an acid-resistant protective layer in a mixed acid solution, and then place it in an organic solvent for soaking after cleaning to obtain a flexible glass with unequal thickness without a protective layer.

[0086] Perform the first tempering on the flexible glass with unequal thickness. Preheat the flexible glass with unequal thickness at 380 °C for 40 min, and then transfer it to a salt furnace containing solid potassium nitrate and sodium nitrate, where the mass ratio of sodium nitrate to potassium nitrate is 3:20. Chemically temper at 400 °C for 15 min. After the chemical tempering is completed, transfer the flexible glass with unequal thickness to a water tank at 55 °C for rapid cooling to complete the first tempering treatment. Subsequently, perform the second tempering on the flexible glass with unequal thickness. Set high-temperature resistant protective layers on the upper and lower surfaces of the unequal thickness part of the flexible glass with unequal thickness. Preheat the flexible glass with unequal thickness at 380 °C for 40 min, and then transfer it to a salt furnace containing solid potassium nitrate and a tempering catalyst. Chemically temper at 420 °C for 10 min. The tempering catalyst is a mixture of potassium hydroxide and potassium chloride, and the molar ratio of potassium ions in potassium nitrate to potassium ions in the tempering catalyst is 15:1. After the chemical tempering is completed, transfer the flexible glass with unequal thickness to a water tank at 55 °C for rapid cooling, and remove the high-temperature resistant protective layer on the glass surface after taking out the glass to complete the second tempering treatment.

[0087] Place the chemically tempered, cleaned and dried flexible glass with unequal thickness as a whole in a mixed acid solution for pickling and micro-thinning, and the thinning thickness is 1.6 μm. Among them, the temperature during the pickling process is controlled at 25 °C, and the pickling and thinning rate is 1.1 μm / min.

[0088] After the above treatment, the minimum thickness of the unequal thickness part of the obtained flexible glass with unequal thickness is 31.8 μm, the magnitude of the compressive stress value CS is 441 MPa, and the depth of the compressive stress layer DOL is 6.1 μm; the maximum thickness of the equal thickness part is 74.9 μm, the magnitude of the compressive stress value CS is 531 MPa, and the depth of the compressive stress layer DOL is 6.2 μm.

[0089] Above, Example 1 and Example 2 respectively show the application of this process in the production of flexible glass with unequal thickness of different thicknesses.

[0090] Comparative Example 1

[0091] Except for the following changes, the rest is the same as that in Example 1.

[0092] Grooving: The glass substrate was cold engraved using a processing platform with a platform Vickers hardness of 100 Kgf / mm 2 to perform cold engraving on the glass substrate.

[0093] Comparative Example 2

[0094] Except for the following changes, the rest is the same as that in Example 1.

[0095] Grooving: The non-uniform thickness part was manufactured by a stepwise etching and thinning process. On both sides of the glass substrate, PO acid-resistant UV reducing films were respectively coated. The coating method for one side was full-surface coating. The coating method for the other side, that is, the surface of the preset non-uniform thickness part, was as follows: Multiple acid-resistant films were coated along the direction from the edge of the non-uniform thickness part to the center on the area where the non-uniform thickness part was to be formed, and the coated films were adhered and connected. An acid-resistant film was coated on the area where the non-uniform thickness part was not to be formed on this surface to ensure that no area of the glass surface was exposed to the air.

[0096] The film in the central part of the preset non-uniform thickness part was removed, and the glass was etched by spray etching. Then, the two adjacent acid-resistant films on both sides of the etched area were continuously removed, and spray etching was performed, and the above steps were repeated.

[0097] Comparative Example 3

[0098] Except for the following changes, the rest is the same as that in Example 2.

[0099] Before grooving, the glass substrate was thinned as follows: The original glass substrate was thinned by spray etching to 75 μm.

[0100] Grooving: An acid-resistant film was adhered to one side of the glass substrate. Subsequently, the glass substrate was bent and fixed on a shaping device so that the glass substrate remained in a bent state with a curvature radius of 80 mm. The film-coated glass surface was in contact with the shaping device. The shaping device was lowered uniformly, and the shaping device was immersed in the etching solution by 30 mm. Subsequently, it was raised uniformly to make the shaping device leave the etching solution. Each immersion was 1 min, and the etching rate was controlled at 1.5 - 2 μm / min. The immersion was repeated 20 times to obtain a non-uniform thickness flexible glass.

[0101] The protection treatment to the pickling process was the same as that in Example 2.

[0102] Comparative Example 4

[0103] Except for the following changes, the rest is the same as that in Example 1.

[0104] The tempering alkali salt in the second tempering was pure solid potassium nitrate.

[0105] Comparative Example 5

[0106] Except for the following changes, the rest is the same as in Example 1.

[0107] Chemical toughening: First, perform the first toughening on the flexible glass with unequal thicknesses. Set high-temperature resistant protective layers on the upper and lower surfaces of the unequal-thickness part of the flexible glass with unequal thicknesses, preheat at 380 °C for 40 min, and then transfer it to a salt furnace containing solid potassium nitrate and toughening catalyst. Perform chemical toughening at 420 °C for 10 min. The toughening catalyst uses a mixture of potassium hydroxide and potassium chloride, and the molar ratio of potassium ions in potassium nitrate to potassium ions in the toughening catalyst is 10:1. Subsequently, transfer it to a water bath at 55 °C for rapid cooling. After taking out the glass, remove the high-temperature resistant protective layer on the glass surface to obtain the glass after the first toughening.

[0108] Subsequently, perform the second toughening on the flexible glass with unequal thicknesses. Preheat the flexible glass with unequal thicknesses at 380 °C for 40 min, and then transfer it to a mixed salt furnace containing solid potassium nitrate and sodium nitrate. Perform chemical toughening at 400 °C for 15 min. The mass ratio of sodium nitrate to potassium nitrate is 1:7. Subsequently, transfer it to a water bath at 55 °C for rapid cooling to obtain the glass after the second toughening.

[0109] Comparative Example 6

[0110] Except for the following changes, the rest is the same as in Example 1.

[0111] Chemical toughening: Only perform single toughening on the flexible glass with unequal thicknesses, and the process is the same as the first toughening in Example 1.

[0112] Comparative Example 7

[0113] Except for the following changes, the rest is the same as in Example 1.

[0114] Chemical toughening: Only perform single toughening on the flexible glass with unequal thicknesses, and the toughening alkali salt is pure solid potassium nitrate alkali salt. The specific process is as follows: Preheat the flexible glass with unequal thicknesses at 380 °C for 40 min, and then transfer it to a salt furnace containing solid potassium nitrate. Perform chemical toughening at 420 °C for 10 min. After the chemical toughening is completed, transfer the flexible glass with unequal thicknesses to a water bath at 55 °C for rapid cooling to complete the toughening treatment.

[0115] Comparative Example 8

[0116] Except for the following changes, the rest is the same as in Example 1.

[0117] Pickling: Immerse the entire flexible glass with unequal thicknesses after chemical toughening, cleaning, and drying in a mixed acid solution for pickling and slight thinning, and the thinning thickness is controlled at 4.1 μm. Among them, the temperature during the pickling process is controlled at 25 °C, and the pickling thinning rate is controlled at 1.3 μm / min.

[0118] Table 1 and Table 2 show the comparison of each example and comparative example in terms of process conditions and performance parameters.

[0119] Comparison of Examples and Comparative Examples in Terms of Process Conditions and Performance Parameters

[0120]

[0121] Compared with the processing platform with a Vickers hardness of 100 Kgf / mm used in Comparative Example 1, 2 the uneven-thickness part processed by the processing platform with a Vickers hardness of 200 Kgf / mm in the present invention has better thickness uniformity. 2

[0122] Compared with the grooving method in Comparative Example 2, the method for preparing the uneven-thickness part by combining the cold carving process and the polishing process in the present invention is more convenient, and the thickness change on both sides of the groove of the processed uneven-thickness part is more continuous, and the thickness uniformity of the uneven-thickness part is better.

[0123] When using the grooving method in Comparative Example 3, it is necessary to bend the glass substrate and immerse it in acid solution for etching. When the thickness of the glass substrate is greater than 200 μm, it is almost impossible to bend, and it needs to be thinned first before bending. Compared with the grooving method in Comparative Example 3, the method for preparing the uneven-thickness part by combining the cold carving process and the polishing process in the present invention can use a thicker original glass substrate without thickness limitation of the glass substrate.

[0124] Table 2, Comparison of Tempering Methods, Tempering Alkali Salt Compositions with Appearance, Bending, and Strength Performance

[0125]

[0126]

[0127] Compared with using pure potassium salt as the tempering alkali salt for the second chemical tempering in Comparative Example 4, a tempering catalyst is added to the tempering alkali salt for the second chemical tempering in the present invention, which improves the exchange degree of potassium and sodium ions in the second tempering and enhances the strength performance of the equal-thickness part.

[0128] Compared with Comparative Example 5, the tempering alkali salts used for the first and second temperings in the present invention have more advantages. For the flexible glass processed by the tempering method described in Comparative Example 5, there are already some potassium ions on the surface of the equal-thickness part after the first tempering, resulting in a smaller potassium ion gradient concentration on the surface of the equal-thickness area during the second tempering, and at the same time, accompanied by the relaxation of the compressive stress, which is likely to cause a decrease in the compressive stress of the equal-thickness part.

[0129] Compared with Comparative Examples 6 and 7, the differential secondary toughening method of the present invention not only optimizes the strength performance of the flexible glass with unequal thickness, but also solves the problem of stress concentration. When a mixed salt of solid potassium nitrate and sodium nitrate is selected as the main toughening alkali salt for single toughening of the flexible glass with unequal thickness, the influence of potassium nitrate on the toughening process is reduced, thereby reducing the wrinkling phenomenon. However, there are problems such as insufficient compressive stress and depth of compressive stress in the equal-thickness part. When the toughening alkali salt is pure potassium nitrate salt for single toughening of the flexible glass with unequal thickness, due to the large thickness difference between the unequal-thickness part and the equal-thickness part, after chemical toughening ion exchange of the flexible glass with unequal thickness, the unequal-thickness area is over-toughened, resulting in a significant difference in toughening expansion between the unequal-thickness area and the equal-thickness area. Wrinkling phenomena appear on the surface of the unequal-thickness area, further intensifying the concentration of compressive stress, and causing the unequal-thickness area to be easily damaged when bent. Compared with the single toughening method in Comparative Examples 6 and 7, the present invention optimizes the chemical toughening scheme and adopts a differential zoning toughening strategy. In the first step, a mixed salt of sodium nitrate and potassium nitrate is used as the toughening alkali salt for overall toughening of the glass. In the second step, a mixture of potassium nitrate and a toughening catalyst is used as the toughening alkali salt for toughening the equal-thickness part, improving the strength performance of the equal-thickness part and protecting the unequal-thickness part at the same time, avoiding its over-toughening.

[0130] Table 3. Comparison of pickling methods with appearance, bending, and strength performance

[0131]

[0132] Compared with Comparative Example 8, the thickness control of the pickling micro-thinning in the present invention provides better protection for the strength performance of the flexible glass with unequal thickness after toughening.

[0133] The above is only the preferred specific implementation mode of the present invention, and the protection scope of the present invention is not limited thereto. Any person skilled in the art can make equivalent substitutions or changes according to the technical solution and inventive concept of the present invention, as well as the application of the present invention in different products, which should be covered by the protection scope of the present invention.

Claims

1. A preparation process for flexible glass with unequal thicknesses, characterized in that, Including: Raw material selection process, wherein the glass substrate material is aluminosilicate glass, borosilicate glass, phosphosilicate glass or glass-ceramics; Grooving process, wherein grooves are machined on the surface of the glass substrate to form an unequal-thickness part; Etching process, wherein the glass substrate with the unequal-thickness part is etched and thinned to form an unequal-thickness flexible glass; Chemical tempering process, wherein, first, the whole unequal-thickness flexible glass is subjected to the first tempering, then high-temperature resistant protective layers are provided on the upper and lower surfaces of the unequal-thickness part, and then the equal-thickness part is subjected to the second tempering; Pickling process, wherein the whole unequal-thickness flexible glass is pickled and slightly thinned.

2. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: The glass substrate material is aluminosilicate glass, and the mass percentages of each component are: 55% - 75% of SiO2, 5% - 22% of Al2O3, 3% - 10% of K2O, 1% - 15% of Na2O, 0% - 5% of CaO, 0% - 5% of SnO2, 0% - 5% of ZnO, 0% - 5% of MgO, 0% - 3% of TiO2, 0.3% - 3% of ZrO2, 0% - 8% of La2O3 and 0.1% - 0.5% of CeO2.

3. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: The grooving process adopts the cold carving process to machine grooves on a processing platform with a Vickers hardness range of 150Kgf / mm 2 ~550Kgf / mm 2 .

4. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: The grooving process uses a cold carving process to machine grooves on a processing platform with a Vickers hardness range of 200Kgf / mm 2 ~450Kgf / mm 2 .

5. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: The grooving process uses a cold carving process to machine grooves on a processing platform with a Vickers hardness range of 250 Kgf / mm 2 ~400 Kgf / mm 2 .

6. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: The grooving process uses a cold carving process to machine grooves on a processing platform with a Vickers hardness range of 300 Kgf / mm 2 ~350 Kgf / mm 2 .

7. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: The tempering alkali salt used in the first tempering is a mixed salt of solid potassium nitrate and solid sodium nitrate.

8. The preparation process of the flexible glass with unequal thickness according to claim 7, characterized in that: The mass ratio range of sodium nitrate to potassium nitrate is 1:9 - 2:

11.

9. The preparation process of the flexible glass with unequal thickness according to claim 7, characterized in that: The mass ratio range of sodium nitrate to potassium nitrate is 1:8 - 3:

17.

10. The preparation process of the flexible glass with unequal thickness according to claim 7, characterized in that: The mass ratio range of sodium nitrate to potassium nitrate is 1:7 - 1:

6.

11. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: The tempering alkali salt used in the second tempering is a mixture of solid potassium nitrate and a tempering catalyst.

12. The preparation process of the flexible glass with unequal thickness according to claim 11, characterized in that: The molar ratio range of potassium ions in potassium nitrate to potassium ions in the catalyst is 30:1 - 10:

1.

13. The toughened alkali salt according to claim 11, characterized in that: The molar ratio range of potassium ions in potassium nitrate to potassium ions in the catalyst is 27:1 - 13:

1.

14. The toughened alkali salt in the toughening method according to claim 11, characterized in that: The molar ratio range of potassium ions in potassium nitrate to potassium ions in the catalyst is 23:1 - 17:

1.

15. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: In the pickling process, the whole unequal-thickness flexible glass is pickled and slightly thinned, and the pickling thickness is 1μm - 2μm.

16. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: In the pickling process, the whole unequal-thickness flexible glass is pickled and slightly thinned, and the pickling thickness is 1.2μm - 1.8μm.

17. The preparation process of the flexible glass with unequal thickness according to claim 1, characterized in that: In the pickling process, the whole unequal-thickness flexible glass is pickled and slightly thinned, and the pickling thickness is 1.4μm - 1.6μm.

18. An unequal-thickness flexible glass, characterized in that: Prepared by the preparation process of the unequal-thickness flexible glass according to any one of claims 1 - 17.

19. Use of the flexible glass with unequal thickness prepared by the preparation process according to any one of claims 1 to 17, characterized in that, The obtained unequal-thickness flexible glass is applied to electronic flexible display screen covers, semiconductor packaging, solar photovoltaic covers, automotive window and body covering materials, preparation of artificial organs or flexible medical devices.

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