A glass substrate for OLED displays with high ultraviolet transmittance and its preparation method.

Abstract

This invention discloses a glass substrate for OLED displays with high ultraviolet transmittance and its preparation method, relating to the field of glass substrates for electronic information displays. Based on the total weight of oxides, its composition includes: 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 glass substrate provided by this invention has high ultraviolet light transmittance and low thermal shrinkage, while its elastic modulus and strain point meet the requirements for use as a glass substrate for OLED displays.

Description

Technical Field

[0001] This invention relates to the field of electronic information display technology, specifically to a glass substrate for OLED displays with high ultraviolet transmittance and its preparation method. 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-layer film (instead of glass) is used to encapsulate the flexible display. Finally, the plastic substrate needs to be peeled off from the glass substrate. Although glass plays a completely different role in these processes, it is crucial in all of them.

[0003] 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 from the glass substrate. The glass substrate must be a high-performance display glass substrate with a clean surface, excellent dimensional stability, and optical properties to enable these two processes. Therefore, ultraviolet light transmittance is crucial (generally, 308nm ultraviolet transmittance is used as the evaluation standard). Furthermore, flexible OLED panels place new demands on the performance of the glass substrate. For example, it must withstand smaller radii of curvature during bending without cracking, and large-size substrates must exhibit minimal sagging during transport. This necessitates improved mechanical properties of the glass substrate. Simultaneously, thermal shrinkage rate, which is the amount of shrinkage deformation of the glass substrate after high-temperature heat treatment at 550℃-600℃, is also important. A lower thermal shrinkage rate improves the quality and production efficiency of high-precision panels; therefore, a lower thermal shrinkage rate is also a requirement for the substrate glass in flexible OLEDs. Summary of the Invention

[0004] The purpose of this invention is to provide a glass substrate for OLED displays with high ultraviolet transmittance and its preparation method. The substrate has high ultraviolet light transmittance, low thermal shrinkage, high elastic modulus and strain point, and meets the requirements for use as a glass substrate for OLED displays.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] An OLED display glass substrate with high ultraviolet transmittance, the glass substrate containing 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;

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

[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 57-59 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;

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

[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 aspect of the present invention: the CaO-introducing substance in 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 glass composition in which BaO is introduced is a combination of BaCO3 and BaSO4, and the mass ratio of BaSO4 / (BaSO4+BaCO3) is 0.1-0.2.

[0016] 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.

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

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

[0019] (1) Mix the components according to the ratio; (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.

[0020] The beneficial effects of this invention are:

[0021] 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.

[0022] 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 is beneficial for preserving 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 the absorption of ultraviolet wavelengths ensures that the glass has high ultraviolet transmittance. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

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

[0025] (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.

[0026] 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.

[0027] 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.

[0028] 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 ℃.

[0029] The present invention is further described below through embodiments, 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 shows the proportion of sulfate introduced in Examples 1-5.

[0034]

[0035] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

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, and 0.35-0.45 wt.% Gd2O3; The combined content of MgO, CaO, SrO, and 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.

2. The glass substrate for OLED displays with high ultraviolet transmittance according to claim 1, characterized in that, The glass substrate 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 combined content of MgO, CaO, SrO, and 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.

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

2. The oxide composition in which BaO is introduced 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 oxide 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 displays with high ultraviolet transmittance 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%.

5. A method for preparing a glass substrate for OLED displays with high ultraviolet transmittance, characterized in that, The preparation of a glass substrate for OLED displays with high ultraviolet transmittance as described in any one of claims 1-4 comprises the following steps: (1) Mix the components according to the ratio; (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. The annealing temperature is 750℃ and the time is 1 hour. Finally, the sample is cooled to room temperature with the furnace to obtain the substrate glass for OLED display.

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