Photochromic composition resistant to fatigue
AssigneeAmerican Optical Corporation
InventorNori Y. C. Chu
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Abstract
An organic photochromic composition comprising spiro [indoline-2,3'-[3H]-naphth [2,1-b] [1,4] oxazine] dye (spirooxazine dye) and unconventional ultraviolet stabilizers. The ultraviolet stabilizers improve the light fatigue resistance of the spirooxazine (S.O.) dye and will not hinder the photocolorability of the photochromic composition. The unconventional ultraviolet stabilizers belong to the class of hindered amine light stabilizers (HALS) and excited state quenchers.
Claims19
A photochromic composition comprising at least one photochromic compound having the structural formula ##STR12## wherein one of R.sub.1, R.sub.2 and R.sub.3 is selected from the group consisting of hydrogen, halogen, lower alkoxy, and lower alkyl and the others are hydrogen;
- R.sub.4 and R.sub.5 are selected from the group consisting of hydrogen, lower alkyl, lower alkoxy, halogen, and trifluoromethyl;
- and R.sub.6 is lower alkyl;
- and a hindered amine light stabilizer.
A spirooxazine photochromic composition having incorporated therein a hindered amine light stabilizer to increase the light fatigue resistance thereof.
A method of increasing the light fatigue resistance of a spirooxazine photochromic composition which comprises incorporating in said composition a hindered amine light stabilizer.
Dependencies are inferred from the claim text.