Claims
- 1. A method of preparing a light polarizing element which comprises:
- uniaxially stretching a film of polyvinyl alcohol; and
- staining the stretched film with an iodine solution; and
- treating the stained film with an aqueous solution containing zinc ion in a concentration effective to stabilize absorption of red light by the polarizer against degradation on heating.
- 2. The method of claim 1 wherein the stained film is treated with an aqueous solution of boric acid.
- 3. The method of claim 2 wherein said solution of boric acid additionally contains potassium iodide.
- 4. The method of claim 2 wherein said boric acid solution contains said zinc ion.
- 5. The method of claim 4 wherein said zinc ion results from dissolving zinc chloride in said solution.
- 6. A method of preparing a light polarizing element which comprises:
- uniaxially stretching a film of polyvinyl alcohol; and
- staining the stretched film with an iodine solution; and
- treating the stained film with an aqueous borating solution containing zinc ion in a concentration effective to stabilize absorption of red light by the polarizer against degradation on heating.
- 7. The method of claim 6 wherein said aqueous borating solution containing zinc ion additionally contains potassium iodide.
- 8. The method of claim 7 wherein said aqueous borating solution comprises boric acid.
- 9. In a light polarizing sheet comprising a uniaxially stretched film of polyvinyl alcohol stained with iodine, the improvement wherein said film comprises zinc ion which is absorbed by said film after it is stained with iodine, in a concentration whereby absorption of red light by said polarizer is stabilized against degradation on heating.
- 10. The polarizer of claim 9 which additionally comprises a complex of said polyvinyl alcohol and boric acid.
- 11. The polarizer of claim 10 which additionally comprises potassium iodide.
- 12. The polarizer of claim 9 which additionally comprises potassium iodide.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of my earlier filed and copending application Ser. No. 810,996 filed June 29, 1977, and now abandoned.
US Referenced Citations (5)
Continuations (1)
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Number |
Date |
Country |
Parent |
810996 |
Jun 1977 |
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