Photochromic glass suitable for microsheet and simultaneous heat treatment and shaping
US4358542A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 8, 1981 |
| Grant date | Nov 9, 1982 |
| Priority date | — |
| Expiry date | Apr 8, 2001 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC03C3/091
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The instant invention is directed to the production of photochromic glasses having compositions consisting essentially, as analyzed in weight percent on the oxide basis, of PA1 SiO.sub.2 --55-60 PA1 Al.sub.2 O.sub.3 --9-10 PA1 B.sub.2 O.sub.3 --19-20.5 PA1 Li.sub.2 O--2-2.5 PA1 Na.sub.2 O--2-3 PA1 K.sub.2 O--6-7 PA1 PbO--0.1-0.25 PA1 Ag--0.1-0.15 PA1 Cl--0.3-0.5 PA1 Br--0.05-0.15 PA1 CuO--0.0065-0.01 The glasses are capable of being drawn into sheet and articles cut from the sheet simultaneously shaped and photochromic properties developed therein. The glasses display a clear luminous transmittance in excess of 90% when free from tint, a darkened luminous transmittance at 20.degree. C. below 25% when free from tint, and a fading rate at 20.degree. C. such that the glass demonstrates a faded luminous transmittance at least twice that of the darkened transmittance after a five-minute fading interval.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.