GLASS PRODUCTION PROCESS
To provide a glass production process capable of reducing bubbles remaining in glass after production, substantially without a refiner. A glass production process, characterized in that glass to be produced is soda lime glass containing water, and the process comprises a step of subjecting molten glass to reduced pressure defoaming in an atmosphere under a pressure of at most the bubble growth starting pressure P eq (kPa) represented by the following formula (1): P eq =−80.8+98.2×[β-OH]+68.0×[SO 3 ]+0.0617× T (1) wherein [β-OH] is the β-OH value (mm −1 ) of glass, [SO 3 ] is the content (as represented by mass percentage based on oxides) of SO 3 in glass, and T is the temperature (° C.) of the molten glass.
1 . A glass production process, characterized in that glass to be produced contains water and consists essentially of, as represented by mass percentage based on the following oxides:
SiO 2
65 to 75%
Al 2 O 3
0 to 3%
CaO
5 to 15%
MgO
0 to 15%
Na 2 O
10 to 20%
K 2 O
0 to 3%
Li 2 O
0 to 5%
Fe 2 O 3
0 to 3%
TiO 2
0 to 5%
CeO 2
0 to 3%
BaO
0 to 5%
SrO
0 to 5%
B 2 O 3
0 to 5%
ZnO
0 to 5%
ZrO 2
0 to 5%
SnO 2
0 to 3%
SO 3
0 to 0.1%
and the process comprises a step of subjecting molten glass to reduced pressure defoaming in an atmosphere under a pressure of at most the bubble growth starting pressure P eq (kPa) represented by the following formula (1):
P eq =−80.8+98.2×[β-OH]+68.0×[SO 3 ]+0.0617 ×T (1)
wherein [β-OH] is the β-OH value (mm −1 ) of glass, [SO 3 ] is the content (as represented by mass percentage based on oxides) of SO 3 in glass, and T is the temperature (° C.) of the molten glass.
2 . The glass production process according to claim 1 , wherein the glass to be produced further contains at least one member selected from the following group:
F, Cl, V, Cr, Mn, Co, Ni, Cu, Se, Mo, Ag, In, Te, La, Pr, Nd, Er, W and Au
3 . The glass production process according to claim 1 , wherein in the glass to be produced, the ratio of FeO based on the whole iron is from 20 to 90%, as represented by the following formula:
FeO/(FeO+Fe 2 O 3 )×100
wherein FeO and Fe 2 O 3 represent contents (as represented by mass percentage based on oxides) of FeO and Fe 2 O 3 , respectively, as calculated as Fe 2 O 3 in the glass to be produced.
4 . The glass production process according to claim 2 , wherein the glass to be produced contains from 0.05 to 0.5% of NiO as represented by mass percentage based on oxides.
5 . The glass production process according to claim 2 , wherein the glass to be produced contains Se, and the ratio of Se remaining in the glass to be produced is from 30 to 60% based on Se introduced as a glass material.