FIELD OF THE INVENTION
[0001] The present invention relates to the field of glass production, specifically opal
glass and a novel composition for opal glass production exhibiting a degree of
5 opacity varying from a very light opalescence to a dense white opal.
We claim:
1. An environmentally friendly spontaneous opal glass demonstrating a dense,
milky-white appearance having a level of opacity in excess of 85% , a
5 softening point less than 765° C but in excess of 735° C, wherein
spherically-shaped, glassy droplets constitute the opal phase containing the
following composition essentially in terms of weight percent on the oxide
basis as calculated from the batch of, 58-74% SiO2, 10-18.5 % Na2 O, 5-
10% BaO, 2-10% Al2 O3, 3-10% B2 O3, 2- 10% CaO, 0.32-3% ZnO , and
10 2-7% P2 O5, wherein, the total of the weight quantities of the ingredients
amounting to 100%, having a density of at least 2.4 g/cm3
and is opacified
as a result of phase separation, and having said that the opal glass
composition is free from elements which are hazardous to environment as
well as human health.
15 2. An environmentally friendly spontaneous opal glass as set forth in claim 1,
characterized in that it has the following composition in terms of weight
percent on the oxide basis, 58-69% SiO2, 11-16.9 % Na2 O, 3-6.9% BaO,
2.7-7.5% Al2 O3, 3-8% B2 O3, 2.5- 8.5% CaO, 0.5-3% ZnO , and 2.8-6.1%
P2 O5, wherein, the total of the weight quantities of the ingredients
20 amounting to 100%.
3. An environmentally friendly spontaneous opal glass as claimed in claim 1,
wherein the glass composition is free from Fluorine (F) and compounds
containing (F).
4. An environmentally friendly spontaneous opal glass as claimed in claim 1,
25 wherein the level of opacity is greater than 85%.
5. An environmentally friendly spontaneous opal glass as claimed in claim 1,
wherein the level of opacity greater than 85% is achieved with minimum
amount of Phosphorous Pentoxide (P2O5).
16
6.