Photochromic plastic article and method for preparing same
AssigneePPG Industries, Inc.
InventorCletus N. Welch
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Abstract
Described is a method for imparting a photochromic response to a synthetic plastic article, e.g., an optical lens such as a sunglass lens prepared from an allyl diglycol carbonate monomer. The method described comprises depositing a thin uniform substantially dry film of a photochromic-bearing polymeric resin onto at least one planar surface of the synthetic plastic material, heating the plastic article and resin film substantially uniformly at temperatures near to but below the melting temperature of the photochromic substance for a time sufficient to transfer a photochromic amount of the photochromic material into the subsurface region of the plastic article, and thereafter removing the photochromic-lean resin film from the planar surface(s) of the plastic article.
Claims31
A method for imparting a photochromic response to a synthetic plastic surface, which comprises:
- (a) applying a substantially mottle-free, substantially homogeneous film of polymeric resin having a spiro(indoline) photochromic material dissolved therein onto said surface, said film having a substantially uniform thickness across the portion of the surface to which it is applied and being substantially dry as soon as it is applied, said polymeric resin being a solvent for the photochromic material and remaining solid at the incorporation temperatures of step (b),
- (b) heating the film-bearing plastic surface at temperatures near to but below the melting temperature of the photochromic material for a time sufficient to incorporate a photochromic amount of the photochromic material into the subsurface of the synthetic plastic surface, and
- (c) thereafter removing the photochromic-lean film from said surface.
Dependencies are inferred from the claim text.