Photochromic glasses which darken to a pink hue
US5300465A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 26, 1993 |
| Grant date | Apr 5, 1994 |
| Priority date | — |
| Expiry date | Jul 26, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S501/905
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A transparent photochromic glass displaying a pink hue in the darkened state which, in bodies of 2 mm cross section, will exhibit the following optical properties: PA0 (a) a clear (undarkened) luminous transmittance greater than 82%; PA0 (b) a darkened luminous transmittance after 15 minutes' exposure to actinic radiation at 25.degree. C. between about 20-32%; PA0 (c) a darkened luminous transmittance after 15 minutes' exposure to actinic radiation at 40.degree. C. between about 35-55%; PA0 (d) a rate of fading such that the luminous transmittance after 5 minutes' removal from actinic radiation at 25.degree. C. will be at least 30 percentage units higher and will exhibit a luminous transmittance greater than 50%; PA0 (e) a x trichromatic coordinate between 0.3500 and 0.3700; and PA0 (f) a y trichromatic coordinate between 0.3250 and 0.3450; said glass consisting essentially, expressed in terms of weight percent on the oxide basis, of ______________________________________ SiO.sub.2 52-58 ZrO.sub.2 1.5-2.8 K.sub.2 O 4-8 B.sub.2 O.sub.3 16-21 Li.sub.2 O 2-3.5 CaO 2-3.5 Al.sub.2 O.sub.3 6-9 Na.sub.2 O 0-2.5 TiO.sub.2 1.2-2.5 ______________________________________ with photochromic ele…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.