G - Physics – 03 – C
Patent
G - Physics
03
C
31/103, 400/7077
G03C 1/72 (2006.01) B60J 1/00 (2006.01) C07D 498/10 (2006.01) C07D 498/20 (2006.01) G02C 7/02 (2006.01) G03C 1/685 (2006.01)
Patent
CA 1305271
ABSTRACT PHOTOCHROMIC ARTICLES A plastic organic photochromic article, typically a lens such as an ophthalmic lens or a window such as a vehicle roof light, comprising a plastics host material having a photochromic compound incorporated therein or applied thereto, the article exhibiting the following properties, measured at Air Mass 2 at 25°C: (a) an integrated visible transmission in the faded state (B.IVT) ranging from 90 to 25%, (b) an integrated visible transmission in the darkened state (D.IVT) ranging from 1 to 50X, preferably 4 to 30X, (c) the rate of darkening of the article when it is exposed to actinic radiation is such that 88X of the darkening range is achieved in 30 seconds or less, i.e. T88 ? 30 secs, (d) the rate of fading of the article from its fully darkened condition is such that more than 60% of the optical density range is recovered in 60 seconds, i.e. % ODG-1 ? 60%, and (e) the induced optical density of the article, i.e. the change in the optical density of the article, in moving from the faded state (B.IVT) to the darkened state (D.IVT), is greater than 0.45 Typically, the photochromic compound is a spiro-oxazine compound of general formula (II), Image (II)
536229
Hepworth John David
Rickwood Martin
Pilkington Plc
Ridout & Maybee Llp
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