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US 5,851,585 AGranted
Impregnation of plastic substrates with photochromic additives
AssigneeInnotech Corporation
InventorsAmitava Gupta, Ronald D. Blum, Venkatramani S. Iyer
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Abstract
The present invention relates to new methods of impregnating plastic substrates with photochromic additives. By impregnating the plastic substrate in multiple impregnation steps under varying conditions, the concentration profile of two or more photochromic additive within the plastic substrate can be independently controlled. Methods are also provided for the distribution of a photochromic additive in a high boiling solvent and for increasing the glass transition temperature of a partially cured polymeric resin.
Claims8
A method comprising:
- forming a solution comprising one or more photochromic additives in a solvent;
- forming a mixture comprising said solution and a liquid, the liquid having a boiling point higher than the boiling point of the solvent;
- applying ultrasonic energy to said mixture;
- and
- heating said mixture to a temperature sufficient to remove said solvent.
2 more elements
Dependencies are inferred from the claim text.