OLED display glass substrate with high ultraviolet transmittance and preparation method thereof

Abstract

The invention discloses a glass substrate with high ultraviolet transmittance for OLED (Organic Light Emitting Diode) display and a preparation method thereof, and relates to the field of glass substrates for electronic information display, and the glass substrate is prepared from the following components in percentage by weight on the basis of the total weight of oxides: 56 to 60 percent of SiO2, 20 to 24 percent of Al2O3, 2 to 3.5 percent of B2O3, 3 to 4 percent of MgO, 3.5 to 4.5 percent of CaO, 2 to 3.5 percent of SrO, 4 to 6.5 percent of BaO, 0.15 to 0.25 percent of SnO2 and 0.8 to 1.50 percent of Yb2O3. And 0.35 to 0.45 wt.% of Gd2O3. The glass substrate provided by the invention has relatively high ultraviolet light transmittance, the thermal shrinkage rate of the glass is relatively low, and the elastic modulus and the strain point both meet the use requirements of the glass substrate for OLED (Organic Light Emitting Diode) display.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic information display, and in particular to a glass substrate for OLED display with high ultraviolet transmittance and a preparation method thereof. Background Art

[0002] The main difference between flexible OLED and traditional TFT-LCD and hard screen OLED is that, first of all, the process of flexible OLED begins with coating and curing high temperature resistant plastic materials such as polyimide on the glass substrate, then using multi-layer film (not glass) to encapsulate the flexible display, and finally the plastic substrate needs to be peeled off from the glass substrate. Although glass plays different roles in these processes, they are all very important.

[0003] For flexible OLED displays, high-performance display glass is used as a substrate in the panel process. It will be cut into half or a quarter of the original size of the substrate before the OLED deposition process, and finally ultraviolet light is used to peel the plastic substrate from the glass substrate. The glass substrate must use a high-performance display glass substrate with a pure surface, excellent dimensional stability and optical properties before these two processes can be carried out. Therefore, the transmittance of ultraviolet light is very important (generally 308nm ultraviolet transmittance is used as the evaluation standard). In addition, flexible OLED panels put forward some new requirements for the performance of glass substrates. For example, when bending, it can withstand a smaller radius of curvature without cracking, and large-size substrates have as little sagging as possible during transmission. This requires improving the requirements for mechanical properties of glass substrates. At the same time, the thermal shrinkage rate is the amount of shrinkage and deformation of the glass substrate after high-temperature heat treatment at 550℃-600℃. The smaller the thermal shrinkage rate, the higher the quality and production efficiency of high-precision panels. Therefore, a lower thermal shrinkage rate is also a requirement for flexible OLEDs on substrate glass. Summary of the invention

[0004] The object of the present invention is to provide a glass substrate for OLED display with high ultraviolet transmittance and a preparation method thereof, which has high ultraviolet transmittance, low thermal shrinkage of the glass, high elastic modulus and strain point, and meets the use requirements of the glass substrate for OLED display.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A glass substrate for OLED display with high ultraviolet transmittance, the glass substrate contains the following oxide composition: 56-60wt.% SiO2, 20-24wt.% Al2O3, 2-3.5wt.% B2O3, 3-4wt.% MgO, 3.5-4.5wt.% CaO, 2-3.5wt.% SrO, 4-6.5wt.% BaO, 0.15-0.25wt.% SnO2, 0.8-1.50wt.% Yb2O3; 0.35-0.45wt.% Gd2O3;

[0007] The total amount of MgO, CaO, SrO and BaO is 14-16wt.%;

[0008] 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;

[0009] The weight ratio of Gd2O3 to Yb2O3 is 0.25-0.40.

[0010] As a further embodiment of the present invention: the oxide contains 57-59wt% SiO2, 22-23wt% Al2O3, 2.5-3wt% B2O3, 3.5-4wt% MgO, 4-4.5wt% CaO, 2-3wt% SrO, 4-6wt% BaO, 0.15-0.2wt% SnO2, 1-1.40wt.% Yb2O3; 0.35-0.40wt% Gd2O3;

[0011] The total amount of MgO, CaO, SrO and BaO is 14.5-15.5wt.%;

[0012] 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;

[0013] The weight ratio of Gd2O3 to Yb2O3 is 0.27-0.35.

[0014] As a further solution of the present invention: 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;

[0015] 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;

[0016] The introduced substance of SrO in 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.

[0017] As a further solution of the present invention: the elastic modulus of the glass substrate is 84-88 GPa, the strain point is 735-750°C, the thermal shrinkage rate when heated to 600°C and cooled to room temperature is 5-8 ppm, and the ultraviolet light transmittance is 83-84%.

[0018] A method for preparing a glass substrate for OLED display with high ultraviolet transmittance comprises the following steps:

[0019] (1) Mix all components according to the proportion; (2) First, heat the temperature from room temperature to 1580°C at a rate of 3°C / min and keep it warm for 2 hours; then heat the temperature from 1580°C to 1710°C at a rate of 2°C / min and keep it warm for 5 hours; (3) Pour the completely melted glass liquid 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, the sample is cooled to room temperature in the furnace to obtain a substrate glass for OLED display.

[0020] Beneficial effects of the present invention:

[0021] Under the premise of controlling the contents of SiO2, Al2O3, B2O3, MgO, CaO, SrO and BaO, the present invention blends SnO2, Yb2O3 and Gd2O3 and accurately adjusts their dosage, thereby giving the glass substrate a higher ultraviolet light transmittance, which is reflected in the transmittance at 308nm reaching 83-84%. At the same time, it has a higher elastic modulus, a higher strain point and a lower thermal shrinkage rate, thus meeting the requirements of glass substrates for OLDE displays, especially flexible OLED glass substrates.

[0022] The glass composition of the present invention introduces CaSO4, BaSO4 and Sr(NO3)2, so that the redox state of the glass batch material is in a partial oxidation state, which is beneficial to ensure that the rare earth ion Gd 3+ With Yb 3+ Stable and will not be reduced to low-valent Yb 2 + Increasing the absorption of the ultraviolet band ensures that the glass has high ultraviolet transmittance. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] A method for preparing a glass substrate for OLED display with high ultraviolet transmittance, the specific implementation steps are as follows:

[0025] (1) Mix the components as shown in Table 1 below; (2) First, heat the temperature from room temperature to 1580°C at a rate of 3°C / min and keep it at that temperature for 2 hours; then heat the temperature from 1580°C to 1710°C at a rate of 2°C / min and keep it at that temperature for 5 hours; (3) Pour the completely melted glass liquid 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, the sample is cooled to room temperature in the furnace to obtain a substrate glass for OLED display.

[0026] Preferably, 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 of 5-9 ppm.

[0027] The glass composition of the present invention is an alkali-free aluminosilicate glass, and is preferably used as a glass substrate for OLED display in electronic information display, especially a flexible OLED glass substrate with high requirements for ultraviolet transmittance.

[0028] In the following embodiments and comparative examples: refer to GBT 38711-2020 and use the laser method to test the thermal shrinkage of the glass, and the unit is ppm; refer to ASTM C-623 and use a glass elastic modulus tester to determine the elastic modulus of the glass, and the unit is GPa; refer to ASTMC-336 and use a three-point tester to determine the strain point of the glass, and the unit is ℃.

[0029] The present invention is further described below by way of examples, but the present invention is not limited thereto.

[0030] Table 1 Comparison of the composition and performance indicators of the present invention with those of the comparative example

[0031]

[0032]

[0033] Table 2 Proportion of the amount of sulfate introduced in Examples 1-5

[0034]

[0035] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A glass substrate for OLED display with high ultraviolet transmittance, characterized in that: The glass substrate contains the following oxide composition: 56-60wt.% SiO2, 20-24wt.% Al2O3, 2-3.5wt.% B2O3, 3-4wt.% MgO, 3.5-4.5wt.% CaO, 2-3.5wt.% SrO, 4-6.5wt.% BaO, 0.15-0.25wt.% SnO2, 0.8-1.50wt.% Yb2O3; 0.35-0.45wt.% Gd2O3; The total amount of MgO, CaO, SrO and BaO is 14-16wt.%; 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.

2. The glass substrate for OLED display with high ultraviolet transmittance according to claim 1, characterized in that: The oxide contains 57-59wt% SiO2, 22-23wt% Al2O3, 2.5-3wt% B2O3, 3.5-4wt% MgO, 4-4.5wt% CaO, 2-3wt% SrO, 4-6wt% BaO, 0.15-0.2wt% SnO2, 1-1.40wt.% Yb2O3; 0.35-0.40wt% Gd2O3; The total amount of MgO, CaO, SrO and BaO is 14.5-15.5wt.%; 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.

3. The glass substrate for OLED display 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; 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 introduced substance of SrO in 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.

4. The glass substrate for OLED display with high ultraviolet transmittance according to claim 1, characterized in that: The elastic modulus of the glass substrate is 84-88 GPa, the strain point is 735-750° C., the thermal shrinkage rate when heated to 600° C. and then cooled to room temperature is 5-8 ppm, and the ultraviolet light transmittance is 83-84%.

5. A method for preparing a glass substrate for OLED display with high ultraviolet transmittance, characterized in that: The steps include: (1) Mix all components according to the proportion; (2) First, heat the temperature from room temperature to 1580°C at a rate of 3°C / min and keep it warm for 2 hours; then heat the temperature from 1580°C to 1710°C at a rate of 2°C / min and keep it warm for 5 hours; (3) Pour the completely melted glass liquid 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, the sample is cooled to room temperature in the furnace to obtain a substrate glass for OLED display.

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