OLED display glass substrate having high ultraviolet transmittance

Abstract

The present invention relates to the field of glass substrates for electronic information displays. Disclosed is an OLED display glass substrate having high ultraviolet transmittance, wherein a composition thereof comprises, on the basis of the total weight of oxides: 56-60 wt.% of SiO2, 20-24 wt.% of Al2O3, 2-3.5 wt.% of B2O3, 3-4 wt.％ of MgO, 3.5-4.5 wt.％ of CaO, 2-3.5 wt.％ of SrO, 4-6.5 wt.％ of BaO, 0.15-0.25 wt.％ of SnO2, 0.8-1.50 wt.％ of Yb2O3, and 0.35-0.45 wt.％ of Gd2O3. The glass substrate provided by the present invention has relatively high ultraviolet light transmittance, with relatively low thermal shrinkage of the glass. In addition, the glass substrate has an elastic modulus and a strain point that both meet requirements for glass substrates for OLED displays.

Description

A glass substrate for OLED displays with high ultraviolet transmittance Technical Field

[0001] This invention relates to the field of electronic information display, and more specifically to a glass substrate for OLED displays. Background Technology

[0002] The main difference between flexible OLED and traditional TFT-LCD and rigid OLED lies in their manufacturing processes. First, the flexible OLED process begins by coating a high-temperature resistant plastic material such as polyimide onto a glass substrate and curing it. Then, a multi-layered thin film (rather than glass) is used to encapsulate the flexible display. Finally, the plastic substrate needs to be peeled off from the glass substrate. While the glass plays distinctly different roles in these processes, both are crucial. For flexible OLED displays, high-performance display glass serves as the substrate in the panel manufacturing process. Before the OLED deposition process, it is cut to half or a quarter of its original size, and finally, ultraviolet light is used to peel the plastic substrate off the glass substrate. The glass substrate must be a high-performance display glass substrate with a clean surface, excellent dimensional stability, and superior optical properties to enable these two processes. Therefore, ultraviolet light transmittance is extremely important (generally, 308nm ultraviolet transmittance is used as the evaluation standard). In addition, flexible OLED panels place new demands on the performance of glass substrates. For example, they need to withstand smaller radii of curvature during bending without cracking, and large-size substrates need to exhibit minimal sagging during transport. This requires improving the mechanical properties of the glass substrate. Meanwhile, thermal shrinkage rate is the amount of shrinkage and deformation of the glass substrate after high-temperature heat treatment at 550℃-600℃. The lower the thermal shrinkage rate, the better the quality and production efficiency of high-precision panels. Therefore, a lower thermal shrinkage rate is also a requirement for the substrate glass of flexible OLEDs. Summary of the Invention

[0003] The purpose of this invention is to provide a glass substrate for OLED displays with high ultraviolet transmittance. This substrate exhibits high ultraviolet light transmittance, low thermal shrinkage, high elastic modulus and strain point, and meets the requirements for use as a glass substrate in OLED displays. To achieve the above objective, this invention provides a glass substrate for OLED displays with high ultraviolet transmittance, comprising the following oxide composition: 56–60 wt.% SiO2, 20–24 wt.% Al2O3, 2–3.5 wt.% B2O3, 3–4 wt.% MgO, 3.5–4.5 wt.% CaO, 2–3.5 wt.% SrO, 4–6.5 wt.% BaO, 0.15–0.25 wt.% SnO2, 0.8–1.50 wt.% Yb2O3, and 0.35–0.45 wt.% Gd2O3. The total amount of (MgO+CaO+SrO+BaO) is 14-16 wt.%; the weight ratio of MgO / (MgO+CaO+SrO+BaO) is 0.20-0.30, and the weight ratio of MgO / (SrO+BaO) is 0.40-0.70; the weight ratio of Gd2O3 to Yb2O3 is 0.25-0.40.

[0004] Preferably, the composition contains 57-59 wt% SiO2, 22-23 wt% Al2O3, 2.5-3 wt% B2O3, 3.5-4 wt% MgO, 4-4.5 wt% CaO, 2-3 wt% SrO, 4-6 wt% BaO, 0.15-0.2 wt% SnO2, 1-1.40 wt% Yb2O3, and 0.35-0.40 wt% Gd2O3. The total amount of (MgO+CaO+SrO+BaO) is 14.5-15.5 wt.%; the weight ratio of MgO / (MgO+CaO+SrO+BaO) is 0.23-0.27, and the weight ratio of MgO / (SrO+BaO) is 0.44-0.67; the weight ratio of Gd2O3 to Yb2O3 is 0.27-0.35.

[0005] The CaO introduced into the glass composition is a combination of CaCO3 and CaSO4, with a CaSO4 / (CaSO4+CaCO3) mass ratio of 0.1–0.2. Similarly, the BaO introduced into the glass composition is a combination of BaCO3 and BaSO4, with a BaSO4 / (BaSO4+BaCO3) mass ratio of 0.1–0.2. The SrO introduced into the glass composition is a combination of SrCO3 and Sr(NO3)2. 3)2 The combination is such that the mass ratio of Sr(NO3)2 / (Sr(NO3)2+SrCO3) is 0.1 to 0.15.

[0006] The glass substrate has an elastic modulus of 84–87 GPa, a strain point of 735–750 °C, a thermal shrinkage rate of 5–8 ppm when heated to 600 °C and cooled to room temperature, and an ultraviolet light transmittance of 83–84% (308 nm).

[0007] This invention, by controlling the contents of SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO, blends SnO2, Yb2O3, and Gd2O3, and precisely adjusts their amounts, which can endow the glass substrate with high ultraviolet light transmittance, manifested in a transmittance of 83-84% at 308nm. At the same time, it has high elastic modulus, high strain point, and low thermal shrinkage rate, meeting the requirements of glass substrates for OLED displays, especially flexible OLED glass substrates.

[0008] The glass composition of this invention, by introducing CaSO4, BaSO4, and Sr(NO3)2, ensures that the redox state of the glass batch is predominantly oxidized, which helps to preserve the rare earth ion Gd. 3+ With Yb 3+ The stability of Yb means it will not be reduced to a low-price state. 2+ Increasing absorption in the ultraviolet band ensures that the glass has high ultraviolet transmittance. Detailed Implementation

[0009] A glass substrate for OLED displays with high ultraviolet transmittance is disclosed, and the specific implementation steps are as follows:

[0010] (1) Mix the components according to Table 1; (2) First, raise the temperature from room temperature to 1580°C at a rate of 3°C / min and hold for 2 hours; then raise the temperature from 1580°C to 1710°C at a rate of 2°C / min and hold for 5 hours; (3) Pour the fully melted glass onto a copper plate for forming and place it in an annealing furnace for annealing at a temperature of 750°C for 1 hour. Finally, cool the sample with the furnace to room temperature to obtain the substrate glass for OLED display.

[0011] In a preferred embodiment, the glass composition of the present invention has an elastic modulus of 82-88 GPa, a strain point of 730-745°C, and a thermal shrinkage rate of 5-9 ppm.

[0012] The glass composition described in this invention is an alkali-free aluminosilicate glass. Its application in electronic information displays is preferably as a glass substrate for OLED displays, especially flexible OLED glass substrates with high requirements for ultraviolet transmittance.

[0013] In the following examples and comparative examples: the thermal shrinkage rate of glass was tested using the laser method according to GB / T 38711-2020, and the unit is ppm; the elastic modulus of glass was determined using a glass elastic modulus tester according to ASTM C-623, and the unit is GPa; the strain point of glass was determined using a three-point tester according to ASTM C-336, and the unit is ℃.

[0014] The present invention is further described below through embodiments, but the present invention is not limited thereto.

[0015] Table 1 Comparison of the composition and performance indicators of the present invention with those of the comparative example.

[0016] Table 2 shows the proportion of sulfate introduced in Examples 1-5.

Claims

1. A glass substrate for OLED displays with high ultraviolet transmittance, characterized in that, The glass substrate contains the following oxide composition: 56–60 wt.% SiO2, 20–24 wt.% Al2O3, 2–3.5 wt.% B2O3, 3–4 wt.% MgO, 3.5–4.5 wt.% CaO, 2–3.5 wt.% SrO, 4–6.5 wt.% BaO, 0.15–0.25 wt.% SnO2, 0.8–1.50 wt.% Yb2O3; 0.35–0.45 wt.% Gd2O3. The total amount of (MgO+CaO+SrO+BaO) is 14-16 wt.%; the weight ratio of MgO / (MgO+CaO+SrO+BaO) is 0.20-0.30, and the weight ratio of MgO / (SrO+BaO) is 0.40-0.70; the weight ratio of Gd2O3 to Yb2O3 is 0.25-0.

40. Preferably, the composition contains 57-59 wt% SiO2, 22-23 wt% Al2O3, 2.5-3 wt% B2O3, 3.5-4 wt% MgO, 4-4.5 wt% CaO, 2-3 wt% SrO, 4-6 wt% BaO, 0.15-0.2 wt% SnO2, 1-1.40 wt% Yb2O3, and 0.35-0.40 wt% Gd2O3. The total amount of (MgO+CaO+SrO+BaO) is 14.5-15.5 wt.%; the weight ratio of MgO / (MgO+CaO+SrO+BaO) is 0.23-0.27, and the weight ratio of MgO / (SrO+BaO) is 0.44-0.67; the weight ratio of Gd2O3 to Yb2O3 is 0.27-0.

35.

2. The glass substrate for OLED displays with high ultraviolet transmittance according to claim 1, characterized in that, The CaO introduced into the glass composition is a combination of CaCO3 and CaSO4, and the mass ratio of CaSO4 / (CaSO4+CaCO3) is 0.1-0.

2. Similarly, the BaO introduced into the glass composition is a combination of BaCO3 and BaSO4, and the mass ratio of BaSO4 / (BaSO4+BaCO3) is 0.1-0.

2. The SrO introduced into the glass composition is a combination of SrCO3 and Sr(NO3)2, and the mass ratio of Sr(NO3)2 / (Sr(NO3)2+SrCO3) is 0.1-0.

15.

3. The flexible OLED display glass substrate according to claim 1, characterized in that, The glass substrate has an elastic modulus of 84–88 GPa, a strain point of 735–750 °C, a thermal shrinkage rate of 5–8 ppm when heated to 600 °C and cooled to room temperature, and an ultraviolet light transmittance of 83–84% (308 nm).

4. The method for preparing a glass substrate for OLED displays with high ultraviolet transmittance according to claim 1, characterized in that... Includes the following steps: (1) Mix the components according to the above proportions; (2) First, raise the temperature from room temperature to 1580℃ at a rate of 3℃ / min and keep it at that temperature for 2 hours; then raise the temperature from 1580℃ to 1710℃ at a rate of 2℃ / min and keep it at that temperature for 5 hours; (3) Pour the fully melted glass onto a copper plate for shaping and place it in an annealing furnace for annealing at a temperature of 750℃ for 1 hour. Finally, cool the sample with the furnace to room temperature to obtain the substrate glass for OLED display.

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