Silver halide activated photochromic plastics
AssigneeAmerican Optical Corporation
InventorsNori Y. C. Chu, Peter G. Piusz
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Abstract
Photochromic plastic materials are disclosed which comprise a polymeric matrix containing a multiplicity of activated silver halide particles less than 1000 Angstroms in size. The matrix may contain a retained amount of plasticizer which optimizes the desirable photochromic properties and may be sealed to prevent loss of plasticizer. The materials are made by forming activated silver halide particles in the presence of a film forming polymer dissolved in a plasticizer and removing the plasticizer to produce a supple, shape-retaining element.
Claims24
A photochromic plastic element comprising a plurality of photosensitive silver halide particles less than 1000 A in particle size containing activating ions which act as hole traps, said particles being dispersed within a cast, shape-retaining, light-transmissive matrix comprising at least one polymer having the ability to inhibit ripening of silver halide particles produced in solution, said matrix containing an effective amount of a plasticizer to produce an environment suitable for repetitive activations and deactivations of the silver halide particles.
A process for producing a photochromic plastic element comprising the steps of:
- forming photosensitive silver halide crystals containing activating ions which act as hole traps, said crystals being less than 1000 A in particle size and being formed in a solution of a light transmissive polymer capable of acting as a ripening inhibitor for the formation of silver halide grains and dissolved in a plasticizer therefor;
- casting said solution;
- and
- removing an effective amount of said plasticizer to form a cast, non-brittle, shape retaining photochromic element.
Process for producing a photochromic plastic element comprising the steps of:
- forming a solution of a polymer chosen from the group consisting of polyvinylpyrrolidone and polyvinylalcohol, water, and a plasticizer chosen from the group consisting of glycerin, ethylene glycol, and polyethylene glycol;
- adding solutions containing Ag.sup.+ ions, halides chosen from the group consiting of Br.sup.- Cl.sup.- I.sup.- and an activating ion chosen from the group consisting of Cu.sup.+ Cd.sup.++ Fe.sup.++ S.sup.-- and mixtures thereof to form activated, photosensitive silver halide crystals having a particle size less than 1000 A in said polymer solution;
- and
- removing the water from the solution to form a non-brittle, shape-retaining plastic element.
Process for producing a photochromic element comprising the steps of:
- forming an aqueous solution of at least one light transmissive water soluble polymer;
- adding aqueous solutions containing silver ions, halide ions, and copper ions to form activated, photosensitive silver halide particles less than 1000A particle size in said polymer solution;
- removing the water from the solution to form a plastic element containing an effective amount of water to maximize the photochromic properties of said element;
- and
- encasing said photochromic plastic element to prevent further loss of water.
Dependencies are inferred from the claim text.