Glass substrate and method for producing same

Abstract

The present invention provides a glass substrate having a high glass transition temperature, in which a compaction (C) is small in heat treatment at low temperature (150 to 300 DEG C). A glass substrate containing, in terms of mol% on the basis of the following oxides: from 60 to 79% of SiO 2 ; from 2.5 to 18% of Al 2 O 3 ; from 0 to 3% of B 2 O 3 ; from 1 to 15% of MgO; from 0 to 1% of CaO; from 0 to 1% of SrO; from 0 to 1% of BaO; from 0 to 1% of ZrO 2 ; from 7 to 15.5% of Na 2 O; from 0 to 3% of K 2 O; and from 0 to 2% of Li 2 O; wherein Na 2 O+K 2 O is from 7 to 15.5%, Na 2 O / (Na 2 O+K 2 O) is from 0.77 to 1, MgO+CaO+SrO+BaO is from 1 to 18%, MgO-0.5Al 2 O 3 is from 0 to 10, and MgO+0.5Al 2 O 3 is from 1 to 20, wherein the glass substrate has: a glass transition temperature of from 580 to 720 DEG C; an average coefficient of thermal expansion within a range of from 50 to 350 DEG C of from 6510 -7 to 8510 -7 / DEG C; a compaction (C) of 15 ppm or less; a glass surface devitrification temperature (T c ) of from 900 to 1,300 DEG C; a glass internal devitrification temperature (T d ) of from 900 to 1,300 DEG C; a temperature (T 4 ) at which a viscosity reaches 10 4 dPas of from 1,100 to 1,350 DEG C; a relationship (T 4 -T c ) between the temperature (T 4 ) at which a viscosity reaches 10 4 dPas and the glass surface devitrification temperature (T c ) of from -50 to 350 DEG C; and a relationship (T 4 -T d ) between the temperature (T 4 ) at which a viscosity reaches 10 4 dPas and the glass internal devitrification temperature (T d ) of from -50 to 350 DEG C.

Description

technical field [0001] The present invention relates to glass substrates. In particular, it is related with the glass substrate for display panels used for various display panels, such as a liquid crystal display (LCD) panel (especially a TFT panel), and a plasma display panel (PDP). Background technique [0002] Conventionally, alkali-free glass that does not contain alkali metal oxides has been used as a glass substrate for LCD panels. The reason is that when the glass substrate contains an alkali metal oxide, the alkali metal ions in the glass substrate may diffuse to the thin film transistor (TFT) used to drive the LCD panel during the heat treatment performed in the LCD panel manufacturing process. In the semiconductor film, the TFT characteristics deteriorate. [0003] In addition, due to the low thermal expansion coefficient and high glass transition temperature (Tg) of alkali-free glass, the dimensional change of the LCD panel during the manufacturing process is sm...

AI Technical Summary

Problems solved by technology

[0010] However, if B 2 o 3 When the content is low, it is difficult to reduce the thermal expansion coefficient to the preferred thermal expansion coefficient as a glass substrate for TFT panels, and it is difficult to obtain a predetermined Tg while suppressing an increase in viscosity.

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