Formable reflective multilayer body

• US 5,448,404 A
• Filed: 05/13/1994
• Issued: 09/05/1995
• Est. Priority Date: 10/29/1992
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Wheatley, John A., Lewis, Ray A., Schrenk, Walter J., Balazs, Conrad F., Arends, Charles B.
• Primary Examiner(s): Lerner, Martin
• Application Number:
  US08/242,713
• Time in Patent Office: 480 Days
• Field of Search: 359/359, 359/586, 359/584, 359/588
• US Class Current: 359/584
• CPC Class Codes: F21S 43/26 Refractors, transparent cover plates, light guides or filters not provided in groups F21S43/235 - F21S43/255
• CPC Class Codes: F21V 3/04 characterised by materials, surface treatments or coatings
• CPC Class Codes: G02B 5/0841 comprising organic materials, e.g. polymers
• CPC Class Codes: G02B 5/26 Reflecting filters G02B5/28 takes precedence
• CPC Class Codes: G02B 5/287 comprising at least one layer of organic material

Abstract

A formable multilayer reflective polymeric body which has a substantially uniform broad bandwidth reflectance over substantially the entire range of the visible spectrum to provide a substantially uniform reflective appearance is provided. The body includes at least first and second diverse polymeric materials, the body comprising a sufficient number of alternating layers of the first and second polymeric materials such that at least 40% of visible light incident on the body is reflected. A substantial majority of the individual layers of the body have optical thicknesses in the range where the sum of the optical thicknesses in a repeating unit of the polymeric materials is greater than about 190 nm, and the first and second polymeric materials differ from each other in refractive index by at least about 0.03.

Claims

1. A formable polymeric multilayer reflective body having a substantially uniform reflective appearance over substantially the entire range of the visible spectrum comprising:

at least first and second diverse polymeric materials, the body comprising a sufficient number of alternating layers of said first and second polymeric materials such that at least 40% of visible light incident on said body is reflected, a substantial majority of the individual layers of said body having optical thicknesses in the range where the sum of the optical thicknesses in a repeating unit of said polymeric materials is greater than about 190 nm, wherein said first and second polymeric materials differ from each other in refractive index by at least about 0.03, wherein said layers have a gradient of optical layer repeat unit thicknesses spanning a range of optical repeating unit thicknesses through the thickness of said body of at least about 190 nm to 340 nm times a predetermined draw ratio of at least about 1.25, and wherein said gradient of optical layer repeat unit thicknesses is a quartic function, said gradient of optical layer repeat unit thicknesses providing continuous wavelength coverage over substantially the entire range of the visible spectrum for said body to maintain a substantially uniform reflective appearance when drawn.

2. The formable polymeric multilayer reflective body of claim 1 in which said gradient of optical layer repeat unit thicknesses is greater than about two.

3. The formable polymeric multilayer reflective body of claim 1 in which said first and second polymeric materials have a repeating unit AB, and the ratio of optical thicknesses between the first and second polymeric materials is 2:

1.

4. The formable polymeric multilayer reflective body of claim 1 in which said gradient of optical layer repeat unit thicknesses is a function which provides substantially continuous wavelength coverage spanning the range of from about 380 nm to about 2000 nm.

5. The formable polymeric multilayer reflective body of claim 1 in which said gradient of optical layer repeat unit thicknesses is a linear function.

6. The formable polymeric multilayer reflective body of claim 1 in which said quartic function which defines said gradient of optical layer repeat unit thicknesses is superimposed on a linear gradient.

7. The formable polymeric multilayer reflective body of claim 1 wherein a substantial majority of the individual layers of said body have optical thicknesses in the range where the sum of the optical thicknesses in a repeating unit of said polymeric materials is between about 190 nm and 1700 nm.

8. The formable multilayer reflective body of claim 1 wherein the reflectance of said body increases upon thinning of said layers.

9. The formable polymeric multilayer reflective body of claim 1 wherein said body has at least 1000 layers.

10. The formable polymeric multilayer reflective body of claim 1 wherein at least 80% of visible light incident on said body is reflected.

11. The formable polymeric multilayer reflective body of claim 1 in which a coloring agent is incorporated into at least one layer of said polymeric body.

12. The formable polymeric multilayer reflective body of claim 11 in which said coloring agent is selected from the group consisting of pigments and dyes.

13. The formable polymeric multilayer reflective body of claim 11 in which said coloring agent is incorporated into at least one surface layer of said polymeric body.

14. The formable polymeric multilayer reflective body of claim 11 in which said coloring agent is incorporated into at least one interior layer of said polymeric body.

15. The formable polymeric multilayer reflective body of claim 1 in which at least one surface layer has a brushed or roughened surface.

16. The formable polymeric multilayer reflective body of claim 1 in which at least one surface layer has been etched to provide a matte or pewter finish.

17. The formable polymeric multilayer reflective body of claim 1 in which at least one surface layer has been embossed.

18. The formable polymeric multilayer reflective body of claim 1 which includes a barrier layer as either an exterior or interior layer of said body.

19. The formable polymeric multilayer reflective body of claim 1 in which said body includes a permanent protective skin layer on at least one major surface thereof.

20. The formable polymeric multilayer reflective body of claim 1 in which said body is extruded as a profile.

21. The formable polymeric multilayer reflective body of claim 1 in which said body is post formed into a profile.

22. The formable polymeric multilayer reflective body of claim 1 in which said polymeric body is in the form of a sheet.

23. The formable polymeric multilayer reflective body of claim 1 in which said polymeric body is blow molded into a container.

24. The formable polymeric multilayer reflective body of claim 1 in which said polymeric body is blow molded into a lighting fixture, globe, or reflector.

25. The formable polymeric multilayer reflective body of claim 1 in which said polymeric materials are elastomers.

26. The formable multilayer reflective body of claim 1 wherein the reflectance of said body decreases upon thinning of said layers.