Method for strengthening flexible glass

Abstract

The invention provides a method for strengthening flexible glass, which is characterized by comprising the following steps: preparing chemical strengthening molten salt (according to mass fraction): mixing 80-95 wt% of potassium nitrate, 2-10 wt% of potassium carbonate, 1-10 wt% of potassium chloride, 0.1-0.5 wt% of cerous nitrate, 0.2-1 wt% of diatomite and 0.2-1 wt% of gamma-aluminum oxide, adding the mixture into a strengthening furnace for heating, the potassium chloride is added into the heated strengthening liquid for at least three times. The flexible glass is subjected to chemical strengthening treatment after being cleaned, dried and preheated. By adopting the molten salt and the strengthening method, the strength of the flexible glass can be improved, and meanwhile, the flexible glass has good surface quality.

Description

Technical Field

[0001] The invention relates to the technical field of glass chemical strengthening, and in particular to a method for strengthening flexible glass. Background Art

[0002] Flexible glass (UTG) refers to ultra-thin glass with a thickness of ≤0.1mm. It is the core material of foldable display devices. It has the characteristics of ultra-thinness, wear resistance, high strength, and bendability. It is an important new development direction. With the rapid development of smart electronic products such as foldable smartphones and bendable electronic wearable devices, higher requirements are placed on flexible displays. The performance of unstrengthened flexible glass, such as bending resistance, scratch resistance, and fracture toughness, often does not meet the requirements. However, due to its own characteristics, the use of traditional chemical strengthening methods will seriously affect its surface quality. The factors affecting the surface quality of flexible glass mainly include: bath salt composition, exchange temperature and time, etc. These factors will lead to uneven stress distribution after strengthening, and the surface quality will decrease when the temperature drops to room temperature. Summary of the invention

[0003] The purpose of the present 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 the flexible glass.

[0004] The present invention adopts the following technical means: A method for strengthening flexible glass, characterized by comprising the following steps: a. Preparation of enhanced molten salt, the molten salt is composed of the following raw materials in percentage by mass: 80-95 wt % of potassium nitrate, 2-10 wt % of potassium carbonate, 1-10 wt % of potassium chloride, 0.1-0.5 wt % of cerium nitrate, 0.2-1 wt % of diatomaceous earth, and 0.2-1 wt % of gamma-alumina; Add the above raw materials into a strengthening furnace and heat to 380-480°C to obtain a strengthening molten salt; b. Cleaning and drying the flexible glass and preheating it to 150-250° C.; adding the preheated flexible glass into the strengthening molten salt described in step a for chemical strengthening treatment for 5-30 min° C. to obtain strengthened flexible glass after chemical strengthening treatment.

[0005] On the basis of the above technical solution, there is the following further technical solution: Said: 0.05≤(potassium carbonate+potassium chloride) / potassium nitrate≤0.2; Said: 0.5 wt %≤(diatomaceous earth+γ-alumina) ≤ 1 wt %.

[0006] During the heating and melting process of the molten salt raw material in step a, potassium chloride is added to the molten salt at least three times to obtain the strengthened molten salt.

[0007] The flexible glass is composed of the following oxides in percentage by mass: 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%.

[0008] The advantages of the present invention are: The present invention proposes a chemical strengthening liquid molten salt and strengthening method according to the characteristics of flexible glass, controls the total content of potassium nitrate to reduce the chemical strengthening speed; diatomaceous earth can not only protect the molten salt from corroding the glass surface, but also can cooperate with γ-alumina to adsorb Ca which is not conducive to chemical strengthening. 2+ and Mg 2+ Impurities such as potassium nitrate and cerium nitrate can be 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 the flexible glass and weaken the strengthening speed of the flexible glass; potassium chloride is added to the strengthening liquid after the temperature is raised at least three times to replenish the strengthening ion concentration in the strengthening liquid in time, which is conducive to the continuous strengthening process. DETAILED DESCRIPTION Example

[0009] a. Preparation of chemically strengthened molten salt (configured by mass fraction): 80.5 wt % potassium nitrate, 10 wt % potassium carbonate, 8 wt % potassium chloride, 0.5 wt % cerium nitrate, 0.5 wt % diatomaceous earth, 0.5 wt % γ-alumina, mixed and added into a strengthening furnace to heat to 380°C; b. After cleaning, drying and preheating, the 70-micron-thick flexible glass is added into the strengthening furnace described in a for chemical strengthening treatment: Flexible glass preheating temperature: 150℃; Chemical strengthening temperature: 380℃; Chemical strengthening time: 30 min℃; Potassium chloride was added to the heated strengthening solution in six portions.

[0010] After the above steps, the strengthened flexible glass is obtained. After testing, the test results are as follows: surface compressive stress CS (MPa): 262; stress layer depth DOL (μm): 15; warpage (mm): 0.07. Example

[0011] a. Preparation of chemically strengthened molten salt (configured 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. After mixing, add them into the strengthening furnace and heat them to 450°C.

[0012] b. After cleaning, drying and preheating, the 70-micron-thick flexible glass is added into the strengthening furnace described in a for chemical strengthening treatment: Flexible glass preheating temperature: 250℃; Chemical strengthening temperature: 450℃; Chemical strengthening time: 5 min℃; Potassium chloride was added to the heated strengthening solution three times.

[0013] After the above steps, the strengthened flexible glass was obtained. After testing, the test results were obtained: surface compressive stress CS (MPa): 326; stress layer depth DOL (μm): 21.3; warpage 0.09mm. Example

[0014] a. Preparation of chemically strengthened molten salt (configured 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. After mixing, add them into the strengthening furnace for heating.

[0015] b. After cleaning, drying and preheating, the 70-micron flexible glass is added into the strengthening furnace described in a for chemical strengthening treatment: Flexible glass preheating temperature: 200℃; Chemical strengthening temperature: 420℃; Chemical strengthening time: 15 min℃; Potassium chloride was added to the heated strengthening solution in four portions.

[0016] After the above steps, the strengthened flexible glass is obtained. After testing, the test results are as follows: surface compressive stress CS (MPa): 297; stress layer depth DOL (μm): 17.4; warpage 0.06mm.

[0017] Comparative Example 1: a. Preparation of chemically strengthened molten salt (configured according to mass fraction) uses pure potassium nitrate for chemical strengthening and is added to the strengthening furnace for heating.

[0018] b. After cleaning, drying and preheating, the 70-micron flexible glass is added into the strengthening furnace described in a for chemical strengthening treatment: Flexible glass preheating temperature: 200℃; Chemical strengthening temperature: 420℃; Chemical strengthening time: 15 min℃; After the above steps, the strengthened flexible glass is obtained. After testing, the test results are as follows: surface compressive stress CS (MPa): 323; stress layer depth DOL (μm): 22.5; warpage 0.28mm.

[0019] Comparative Example 2: a. Preparation of chemically strengthened molten salt (configured 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. After mixing, add them into the strengthening furnace for heating.

[0020] b. After cleaning, drying and preheating, the 70-micron flexible glass is added into the strengthening furnace described in a for chemical strengthening treatment: Flexible glass preheating temperature: 150℃; Chemical strengthening temperature: 380℃; Chemical strengthening time: 30 min℃; Potassium chloride was added to the heated strengthening solution in six portions.

[0021] After the above steps, the strengthened flexible glass is obtained. After testing, the test results are as follows: surface compressive stress CS (MPa): 226; stress layer depth DOL (μm): 10; warpage 0.09mm.

[0022] Comparative Example 3: a. Preparation of chemically strengthened molten salt (configured 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. After mixing, add them into the strengthening furnace for heating.

[0023] b. After cleaning, drying and preheating, the 70-micron flexible glass is added into the strengthening furnace described in a for chemical strengthening treatment: Flexible glass preheating temperature: 200℃; Chemical strengthening temperature: 420℃; Chemical strengthening time: 15 min℃; Potassium chloride was added to the heated strengthening solution in four portions.

[0024] After the above steps, the strengthened flexible glass is obtained. After testing, the test results are 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 The following steps are involved: a. Preparation of enhanced molten salt, the molten salt is composed of the following raw materials in percentage by mass: 80-95 wt % of potassium nitrate, 2-10 wt % of potassium carbonate, 1-10 wt % of potassium chloride, 0.1-0.5 wt % of cerium nitrate, 0.2-1 wt % of diatomaceous earth, and 0.2-1 wt % of gamma-alumina; Add the above raw materials into a strengthening furnace and heat to 380-480°C to obtain a strengthening molten salt; b. Cleaning and drying the flexible glass and preheating it to 150-250° C.; adding the preheated flexible glass into the strengthening molten salt described in step a for chemical strengthening treatment for 5-30 min° C. to obtain strengthened flexible glass after chemical strengthening treatment.

2. A method for strengthening flexible glass according to claim 1, characterized in that: Said: 0.05≤(potassium carbonate+potassium chloride) / potassium nitrate≤0.

2.

3. A method for strengthening flexible glass according to claim 1 or 2, characterized in that: Said: 0.5 wt %≤(diatomaceous earth+γ-alumina) ≤ 1 wt %.

4. 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 at least three times to obtain the strengthened molten salt.

5. A method for strengthening flexible glass according to claim 1 or 2, characterized in that: The flexible glass is composed of the following oxides in percentage by mass: 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 Li2O0.5-3%.