Glass substrate for flat panel display and method for manufacturing same
A substrate for p-Si TFT flat panel displays made of a glass having a high low-temperature-viscosity characteristic temperature and manufactured while avoiding erosion/wear of a melting tank during melting through direct electrical heating. The glass substrate comprises 52-78 mass % of SiO 2 , 3-25 mass % of Al 2 O 3 , 3-15 mass % of B 2 O 3 , 3-20 mass % of RO, wherein RO is total amount of MgO, CaO, SrO, and BaO, 0.01-0.8 mass % of R 2 O, wherein R 2 O is total amount of Li 2 O, Na 2 O, and K 2 O, and 0-0.3 mass % of Sb 2 O 3 , and substantially does not comprise As 2 O 3 , wherein the mass ratio CaO/RO is equal to or greater than 0.65, the mass ratio (SiO 2 +Al 2 O 3 )/B 2 O 3 is in a range of 7-30, and the mass ratio (SiO 2 +Al 2 O 3 )/RO is equal to or greater than 5. A related method involves melting glass raw materials blended to provide the glass composition; a forming step of forming the molten glass into a flat-plate glass; and an annealing step of annealing the flat-plate glass.
1. A glass substrate for a display, the glass substrate being composed of a glass comprising
52-78 mass % of SiO 2 ,
3-25 mass % of Al 2 O 3 ,
3-15 mass % of B 2 O 3 ,
3-20 mass % of RO, wherein RO is total amount of MgO, CaO, SrO, and BaO,
0.01-0.8 mass % of R 2 O, wherein R 2 O is total amount of Li 2 O, Na 2 O, and K 2 O, and
0-0.3 mass % of Sb 2 O 3 , and substantially not comprising As 2 O 3 ,
the glass having
a mass ratio CaO/RO equal to or greater than 0.65,
a mass ratio (SiO 2 +Al 2 O 3 )/B 2 O 3 in a range of 7-30,
a mass ratio (SiO 2 +Al 2 O 3 )/RO equal to or greater than 5,
a mass ratio CaO/B 2 O 3 in a range of 0.7 to 5,
and a strain point equal to or greater than 688° C.
2. The glass substrate according to claim 1 , wherein the glass substantially does not comprise Sb 2 O 3 .
3. The glass substrate according to claim 1 , wherein the glass substantially does not comprise Sb 2 O 3 , and has a mass ratio (SiO 2 +Al 2 O 3 )/B 2 O 3 in a range of 8.1-20.
4. The glass substrate according to claim 1 , wherein the glass substantially does not comprise Cl.
5. The glass substrate according to claim 1 , wherein the glass has a total amount of SrO and BaO of 0 to less than 3.4 mass %.
6. The glass substrate according to claim 1 , wherein:
the glass exhibits a devitrification temperature equal to or lower than 1250° C. or lower; and
the glass substrate has been formed by down-draw processing.
7. A TFT liquid crystal display comprising the glass substrate according to claim 1 .
8. A flat panel display comprising the glass substrate according to claim 1 .
9. A method for manufacturing a glass substrate for display, the method comprising:
a melting step of obtaining a molten glass by melting, by employing at least direct electrical heating, glass raw materials blended so as to provide a glass comprising:
52-78 mass % of SiO 2 ,
3-25 mass % of Al 2 O 3 ,
3-15 mass % of B 2 O 3 ,
3-20 mass % of RO, wherein RO is total amount of MgO, CaO, SrO, and BaO,
0.01-0.8 mass % of R 2 O, wherein R 2 O is total amount of Li 2 O, Na 2 O, and K 2 O, and
0-0.3 mass % of Sb 2 O 3 , and substantially not comprising As 2 O 3 ,
the glass having a mass ratio CaO/RO equal to or greater than 0.65, a mass ratio (SiO 2 +Al 2 O 3 )/B 2 O 3 in a range of 7-30, a mass ratio (SiO 2 +Al 2 O 3 )/RO equal to or greater than 5, a mass ratio CaO/B 2 O 3 in a range of 0.7 to 5, and a strain point equal to or greater than 688° C.;
a forming step of forming the molten glass into a flat-plate glass; and
an annealing step of annealing the flat-plate glass.
10. The method for manufacturing a glass substrate according to claim 9 , wherein the glass substantially does not comprise Sb 2 O 3 , and has a mass ratio (SiO 2 +Al 2 O 3 )/B 2 O 3 in a range of 8.1-20.
11. The manufacturing method according to claim 9 , wherein the specific resistance of the molten glass in a molten state at 1550° C. is 50-300 Ω·cm.
12. The manufacturing method according to claim 9 , wherein a heat shrinkage reduction process of reducing the heat shrinkage rate by controlling the cooling rate of the flat-plate glass is performed in the annealing step.
13. The manufacturing method according to claim 12 , wherein the heat-shrinkage reduction process performed in the annealing step is a process in which cooling rate in a central section of the flat-plate glass is set to 50-300° C./minute within a temperature range of from Tg to 100° C. below Tg.