Time color indicator
AssigneeHerculite Protective Fabrics Corporation
InventorsAgis F. Kydonieus, Inja K. Smith, Reid A. Conroy, Ernest A. Pedicano
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Abstract
A laminated indicator which changes in a visually perceptible mode with the passage of time and a method for making such an indicator. At least two layers are provided whereby the molecular migration of an agent in an interior layer to the outermost surface of the exterior layer causes a change which can be visually percepted, e.g., a change in color or shade. Preferred embodiments include the migration of a dye or the migration of an acid or base wherein the outermost layer has the other member of an acid-base pair and a pH indicator.
Claims18
A solid, non-porous time indicator comprising a laminate which comprises
- (i) a solid, non-porous polymeric substrate having a first and a second surface;
- and
- (ii) a layer of a solid, non-porous polymeric composition adhered to the first surface of said substrate and containing an agent capable of migrating throughout said substrate to cause a visually perceptible change in the substrate at the second surface thereof.
A method of forming a time indicator comprising bringing the first surface of a solid, non-porous polymeric substrate having a first and a second surface into contact with a layer of a solid non-porous polymeric composition containing an agent capable of migrating throughout said substrate to cause a visually perceptible change in the substrate at the second surface thereof.
Dependencies are inferred from the claim text.