Formulation for alkali-free glass

Abstract

The invention relates to a prescription of alkali-free glass, which contains 54-67 percent of SiO2, 7-12 percent of B2O3, 13-18 percent of Al2O3, 0-<2.0 percent of MgO, 3-12 percent of CaO, 0.2-8 percent of SrO, 0.2-10 percent of BaO, 0.001-<2 percent of BeO, 0.001-<2 percent of ZnO, 0.001-<2 percent of ZrO2 and 0.20-1.50 percent of clarifying agent according to weight percent, wherein, the content of SiO2+Al2O3+B2O3 is about 80-92 percent, Al2O3+B2O3 is about 20-30 percent, RO (R is Mg, Ca, Sr, Ba, Be, Zn) 8-20 percent, SrO+BaO 1-12 percent, while on weight ratio, RO / Al2O3 is 0.9-1.2 and CaO / (SrO+BaO) is 0.3-6. The light transmission of the glass is more than 96 percent when the alkali-free glass is in the light with the wavelength of 500 to 650nm, bending strength larger than 110MPa, Webster hardness larger than 550 multiplied by 10<-7>N / m<2>, strain point larger than 650 DEG C, the thermal expansion coefficient is 28-39 multiplied by 10<-7> / DEG C in the range of 0-300 DEG C, the liquidus temperature lower than 1250 DEG C, density 2.35-2.55g / cm<3> and elastic modulus larger than 70GPa; the viscosity is larger than 1000Pa.s under the temperature of liquidus temperature.

Description

technical field [0001] The invention relates to an alkali-free glass composition, in particular to a formula of alkali-free glass. Background technique [0002] A liquid crystal display (LCD) is formed by enclosing liquid crystal between two glass substrates, and the liquid crystal is displayed by applying a voltage. The substrate has two functions, the first is to maintain a certain thickness of the liquid crystal; the second is to carry the transparent electrodes and switching elements necessary for driving. There is a strict size interval between the two substrate glasses, and the interval size is 5-10 μm. [0003] In order to cope with the development of LCD technology, substrate glass has various compositions, manufacturing methods and characteristics. LCD has very strict requirements on the nature of the substrate glass itself and the quality of the panel. The requirements of LCD on the substrate glass are as follows. [0004] First, dimensional accuracy The high-pe...

AI Technical Summary

Problems solved by technology

However, this process has high requirements on the control of the production process. The flow rate, temperature, and tension of the clamping machine must be controlled synchronously and accurately. A slight change may cause the excessive tension of the clamping machine to break the glass plate.

However, once the breakage of the glass plate occurs, it often takes a long time to re-lead the plate, etc., which reduces the production efficiency and production yield rate.