A method for strengthening flexible glass

Abstract

This invention provides a method for strengthening flexible glass, characterized by the following steps: Preparation of a chemical strengthening molten salt (prepared according to mass fractions): potassium nitrate 80-95 wt%, potassium carbonate 2-10 wt%, potassium chloride 1-10 wt%, cerium nitrate 0.1-0.5 wt%, diatomaceous earth 0.2-1 wt%, and γ-alumina 0.2-1 wt. The mixture is added to a strengthening furnace and heated. Potassium chloride is added to the strengthened solution in at least three portions after heating. The flexible glass is then cleaned, dried, and preheated before undergoing chemical strengthening treatment. This molten salt and strengthening method can improve the strength of flexible glass while maintaining good surface quality.

Description

Technical Field

[0001] This invention relates to the field of glass chemical strengthening technology, and in particular to a method for strengthening flexible glass. Background Technology

[0002] Flexible glass (UTG) refers to ultra-thin glass with a thickness of ≤0.1mm. It is a core material for foldable display devices, possessing characteristics such as ultra-thinness, wear resistance, high strength, and bendability, representing an important new development direction. With the rapid development of smart electronic products such as foldable smartphones and flexible wearable devices, higher demands are being placed on flexible displays. Unstrengthened flexible glass often fails to meet requirements in terms of properties such as bending resistance, scratch resistance, and fracture toughness. However, due to its inherent characteristics, traditional chemical strengthening methods severely affect the surface quality of flexible glass. Factors affecting the surface quality of flexible glass include bath salt composition, exchange temperature, and time. These factors can lead to uneven stress distribution after strengthening, and a decline in surface quality when the temperature drops to room temperature. Summary of the Invention

[0003] The purpose of this invention is to provide a method for strengthening flexible glass, so as to effectively control the depth of the stress layer after chemical strengthening, thereby improving the strength and surface quality of flexible glass.

[0004] The present invention employs the following technical means:

[0005] A method for strengthening flexible glass, characterized by comprising the following steps:

[0006] a. Preparation of enhanced molten salt, wherein the molten salt is composed of the following raw materials in the indicated mass percentages: potassium nitrate 80-95 wt%, potassium carbonate 2-10 wt%, potassium chloride 1-10 wt%, cerium nitrate 0.1-0.5 wt%, diatomaceous earth 0.2-1% wt%, and γ-alumina 0.2-1% wt;

[0007] The above raw materials are added to an intensification furnace and heated to 380-480℃ to obtain intensified molten salt;

[0008] b. After cleaning and drying, the flexible glass is preheated to 150-250℃. The preheated flexible glass is added to the strengthening molten salt described in step a for chemical strengthening treatment for 5-30 min. After chemical strengthening treatment, the strengthened flexible glass is obtained.

[0009] Based on the above technical solutions, the following further technical solutions are proposed:

[0010] The stated ratio is: 0.05 ≤ (potassium carbonate + potassium chloride) / potassium nitrate ≤ 0.2;

[0011] The stated content is: 0.5 wt% ≤ (diatomaceous earth + γ-alumina) ≤ 1 wt%.

[0012] During the heating and melting process of the molten salt raw material in step a, potassium chloride is added to the molten salt in at least three portions to obtain a reinforced molten salt.

[0013] The flexible glass is composed of the following oxides by mass percentage: SiO2 55~65%, Al2O3 10~18%, B2O3 0.5~0.2%, MgO 1~6%, Na2O 6~12%, K2O 0.5~5%, CaO 1~5%, ZrO2 0.1~0.8%, TiO2 0.1~0.8%, La2O3 0.1~0.8%, and Li2O 0.5~3%.

[0014] The advantages of this invention are:

[0015] This invention proposes a chemical strengthening solution molten salt and strengthening method for flexible glass, controlling the total potassium nitrate content to reduce the chemical strengthening rate. Diatomaceous earth not only protects the glass surface from erosion by the molten salt but also synergistically adsorbs Ca, which is detrimental to chemical strengthening, with γ-alumina. 2+ and Mg 2+ Impurities such as potassium nitrate, cerium nitrate, and potassium carbonate are removed to improve the efficiency of chemical strengthening processing. The gases generated by the decomposition of potassium nitrate, cerium nitrate, and potassium carbonate adhere to the surface of flexible glass, reducing the strengthening speed of flexible glass. Potassium chloride is added to the strengthening solution at least three times after heating to replenish the concentration of strengthening ions in the strengthening solution in a timely manner, which is conducive to the continuous strengthening process. Detailed Implementation Example

[0016] a. Preparation of chemically fortified molten salt (according to mass fraction): potassium nitrate 80.5 wt%, potassium carbonate 10 wt%, potassium chloride 8 wt%, cerium nitrate 0.5 wt%, diatomaceous earth 0.5 wt%, γ-alumina 0.5 wt%, mixed and added to a fortification furnace and heated to 380℃;

[0017] b. After cleaning, drying, and preheating, the 70-micron-thick flexible glass is added to the strengthening furnace described in step a for chemical strengthening treatment:

[0018] Flexible glass preheating temperature: 150℃;

[0019] Chemical strengthening temperature: 380℃;

[0020] Chemical fortification time: 30 min℃;

[0021] Potassium chloride was added to the heated enhancement solution in six portions.

[0022] The flexible glass obtained after the above steps was tested and the results were as follows: surface compressive stress CS (MPa): 262; stress layer depth DOL (μm): 15; warpage (mm): 0.07. Example

[0023] a. Preparation of chemically fortified molten salt (according to mass fraction): 94 wt% potassium nitrate, 3 wt% potassium carbonate, 2.4 wt% potassium chloride, 0.1 wt% cerium nitrate, 0.2 wt% diatomaceous earth, and 0.3 wt% γ-alumina are mixed and added to a fortification furnace and heated to 450℃.

[0024] b. After cleaning, drying, and preheating, the 70-micron-thick flexible glass is added to the strengthening furnace described in step a for chemical strengthening treatment:

[0025] Flexible glass preheating temperature: 250℃;

[0026] Chemical strengthening temperature: 450℃;

[0027] Chemical fortification time: 5 min℃;

[0028] Potassium chloride was added to the heated enhancement solution in three portions.

[0029] The strengthened flexible glass obtained after the above steps was tested, and the results were as follows: surface compressive stress CS (MPa): 326; stress layer depth DOL (μm): 21.3; warpage 0.09mm. Example

[0030] a. Preparation of chemically enhanced molten salt (according to mass fraction): 90 wt% potassium nitrate, 5 wt% potassium carbonate, 4 wt% potassium chloride, 0.2 wt% cerium nitrate, 0.4 wt% diatomaceous earth, and 0.4 wt% γ-alumina are mixed and added to the enhancement furnace for heating.

[0031] b. After cleaning, drying, and preheating, the 70-micron flexible glass is added to the strengthening furnace described in step a for chemical strengthening treatment:

[0032] Flexible glass preheating temperature: 200℃;

[0033] Chemical strengthening temperature: 420℃;

[0034] Chemical fortification time: 15 min at ℃;

[0035] Potassium chloride was added to the heated enhancement solution in four portions.

[0036] The strengthened flexible glass obtained after the above steps was tested and the results were as follows: surface compressive stress CS (MPa): 297; stress layer depth DOL (μm): 17.4; warpage 0.06mm.

[0037] Comparative Example 1:

[0038] a. Preparation of chemically fortified molten salt (according to mass fraction): Pure potassium nitrate is used for chemical fortification, and the salt is added to the fortification furnace and heated.

[0039] b. After cleaning, drying, and preheating, the 70-micron flexible glass is added to the strengthening furnace described in step a for chemical strengthening treatment:

[0040] Flexible glass preheating temperature: 200℃;

[0041] Chemical strengthening temperature: 420℃;

[0042] Chemical fortification time: 15 min at ℃;

[0043] The strengthened flexible glass obtained after the above steps was tested and the results were as follows: surface compressive stress CS (MPa): 323; stress layer depth DOL (μm): 22.5; warpage 0.28mm.

[0044] Comparative Example 2:

[0045] a. Preparation of chemically enhanced molten salt (according to mass fraction): 80 wt% potassium nitrate, 10 wt% potassium carbonate, 9 wt% potassium chloride, 0.2 wt% cerium nitrate, 0.4 wt% diatomaceous earth, and 0.4 wt% γ-alumina are mixed and added to the enhancement furnace for heating.

[0046] b. After cleaning, drying, and preheating, the 70-micron flexible glass is added to the strengthening furnace described in step a for chemical strengthening treatment:

[0047] Flexible glass preheating temperature: 150℃;

[0048] Chemical strengthening temperature: 380℃;

[0049] Chemical fortification time: 30 min℃;

[0050] Potassium chloride was added to the heated enhancement solution in six portions.

[0051] The strengthened flexible glass obtained after the above steps was tested and the results were as follows: surface compressive stress CS (MPa): 226; stress layer depth DOL (μm): 10; warpage 0.09mm.

[0052] Comparative Example 3:

[0053] a. Preparation of chemically enhanced molten salt (according to mass fraction): 90.4 wt% potassium nitrate, 5 wt% potassium carbonate, 4 wt% potassium chloride, 0.2 wt% cerium nitrate, 0.2 wt% diatomaceous earth, and 0.2 wt% γ-alumina are mixed and added to the enhancement furnace for heating.

[0054] b. After cleaning, drying, and preheating, the 70-micron flexible glass is added to the strengthening furnace described in step a for chemical strengthening treatment:

[0055] Flexible glass preheating temperature: 200℃;

[0056] Chemical strengthening temperature: 420℃;

[0057] Chemical fortification time: 15 min at ℃;

[0058] Potassium chloride was added to the heated enhancement solution in four portions.

[0059] The strengthened flexible glass obtained after the above steps was tested and the results were as follows: surface compressive stress CS (MPa): 263; stress layer depth DOL (μm): 12.4; warpage 0.06mm.

Claims

1. A method for strengthening flexible glass, characterized in that... Includes the following steps: a. Preparation of enhanced molten salt, wherein the molten salt is composed of the following raw materials in the indicated mass percentages: potassium nitrate 80-95 wt%, potassium carbonate 2-10 wt%, potassium chloride 1-10 wt%, cerium nitrate 0.1-0.5 wt%, diatomaceous earth 0.2-1 wt%, and γ-alumina 0.2-1 wt%; the above raw materials are added to an enhanced furnace and heated to 380-480℃ to obtain the enhanced molten salt; b. After cleaning and drying, the flexible glass is preheated to 150~250℃; the preheated flexible glass is added to the strengthening molten salt described in step a for chemical strengthening treatment for 5~30 min, and the strengthened flexible glass is obtained after chemical strengthening treatment. 0.05 ≤ (potassium carbonate + potassium chloride) / potassium nitrate ≤ 0.2; 0.5 wt% ≤ (diatomaceous earth + γ-alumina) ≤ 1 wt%.

2. The method for strengthening flexible glass according to claim 1, characterized in that, During the heating and melting process of the molten salt raw material in step a, potassium chloride is added to the molten salt in at least three portions to obtain a reinforced molten salt.

3. A method for strengthening flexible glass according to claim 1 or 2, characterized in that, The flexible glass is composed of the following oxides by mass percentage: SiO2 55~65%, Al2O3 10~18%, B2O3 0.5~0.2%, MgO 1~6%, Na2O 6~12%, K2O 0.5~5%, CaO 1~5%, ZrO2 0.1~0.8%, TiO2 0.1~0.8%, La2O3 0.1~0.8%, and Li2O 0.5~3%.