Glass article
The present invention relates to a glass article having high transmittance, while suppressing the discoloration and the solarization of the glass. The glass article is provided by controlling the contents of cerium oxide and iron oxide in the glass composition within the optimum range, further controlling the contents of manganese oxide and iron oxide in the glass composition within the optimum range, and controlling the basicity of the alkaline earth metal oxides in the glass composition depending on the iron amount contained in the glass.
1. A glass article comprising a glass comprising, in terms of mass % or mass ppm on the basis of the following oxides, 50 to 80% of SiO 2 , 0 to 10% of K 2 O, 1 to 80 ppm of total iron oxide (t-Fe 2 O 3 ) in terms of Fe 2 O 3 , 0 to 10 ppm of ferrous iron (Fe 2+ ) in terms of Fe 2 O 3 , 0.01 to 5 ppm of total manganese oxide (t-MnO 2 ) in terms of MnO 2 , and 1 to 35% of at least one selected from the group consisting of alkaline earth metal oxides of MgO, CaO, SrO and BaO, in a total amount thereof,
wherein, in the glass, redox of iron represented by the following formula (1) is from 0 to 30%:
(Content of ferrous iron (Fe 2+ ) in terms of Fe 2 O 3 )/[(total content (Fe 2+ +Fe 3+ ) of ferrous iron (Fe 2+ ) and ferric iron (Fe 3+ ) in terms of Fe 2 O 3 ] formula (1),
and the glass satisfies relational formulae of the following formulae (5), (6) and (8):
[ t -CeO 2 ]/[ t -Fe 2 O 3 ]<1 formula (5),
0.001≤[ t -MnO 2 ]/[ t -Fe 2 O 3 ]≤0.5 formula (6),
80≤(64×[MgO]+100×[CaO]+127×[SrO]+156×[BaO])≤2500 formula (8),
wherein, in formulae (5), (6) and (8), [t-CeO 2 ] is the content (mass ppm) of the total cerium oxide, [t-MnO 2 ] is the content (mass ppm) of the total manganese oxide, [t-Fe 2 O 3 ] is the content (mass ppm) of the total iron oxide, [MgO] is the content (mass %) of MgO, [CaO] is the content (mass %) of CaO, [SrO] is the content (mass %) of SrO, and [BaO] is the content (mass %) of BaO.
2. The glass article according to claim 1 , wherein the glass comprises, in terms of mass ppm, 0 to 4 ppm of ferrous iron (Fe 2+ ) in terms of Fe 2 O 3 .
3. The glass article according to claim 1 , wherein the glass contains substantially none of B 2 O 3 .
4. The glass article according to claim 1 , wherein the glass further comprises, in terms of mass %, more than 0% and 0.5% or less of SO 3 .
5. The glass article according to claim 1 , wherein the glass further comprises, in terms of mass %, 0 to 1% of SnO 2 .
6. The glass article according to claim 1 , wherein the glass has 85% or more of a minimum value of the transmittance within a range of wavelengths from 400 to 700 nm under conditions of an effective optical path length of 50 mm, and the difference between a maximum value and the minimum value of the transmittance is 3.8% or less.
7. The glass article according to claim 1 , wherein the glass is a glass plate at least one side of which has a length of 200 cm or less and which has a thickness of 0.5 mm or more.
8. The glass article according to claim 1 , wherein at least one of end faces of the glass plate is polished.