High light diffusive and low light absorbent material and method for making and using same

• US 5,781,342 A
• Filed: 11/27/1995
• Issued: 07/14/1998
• Est. Priority Date: 01/06/1995
• Status: Expired due to Term

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: WL Gore and Associates Incorporated (W.L. Gore and Associates)
• Inventors: Minor, Raymond B., McGregor, Gordon L., Hannon, Gregory E.
• Primary Examiner(s): Callahan, Timothy P.
• Assistant Examiner(s): KIM, JUNG H
• Application Number:
  US08/562,651
• Time in Patent Office: 960 Days
• Field of Search: 359/599, 359/515, 362/341, 428/315.5, 428/311.1, 428/314.7, 521/142, 526/242, 526/250, 526/255
• US Class Current: 359/599
• CPC Class Codes: B29K 2027/18 PTFE, i.e. polytetrafluorethene , e.g. ePTFE, i.e. expanded polytetrafluorethene
• CPC Class Codes: C08J 2327/18 Homopolymers or copolymers of tetrafluoroethylene
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08L 27/18 Homopolymers or copolymers or tetrafluoroethene
• CPC Class Codes: F21V 7/24 characterised by the material
• CPC Class Codes: F21V 7/28 characterised by coatings
• CPC Class Codes: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02B 5/0247 by means of voids or pores
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02B 5/0289 used as a transflector
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605

Abstract

The present invention is an improved material and method for use for providing diffuse transflectance of light. By employing an expanded polytetrafluoroethylene (PTFE) comprising a microstructure of polymeric nodes and fibrils, the material of the present invention demonstrates exceptional diffuse reflectivity and transmission of light across a wide spectrum of ultraviolet, visible, and infrared light. Additionally, the material of the present invention provides many properties that have been previously unavailable in highly diffuse transflective material, including a high degree of malleability, moldability and flexibility, and effective reflectivity even at relatively thin cross-sections.

Claims

1. A method of redirecting light comprising

providing a light redirecting material comprising an expanded polytetrafluoroethylene having polymeric nodes interconnected by fibrils defining microporous voids therein;

mounting the light redirecting material to cause light energy to contact the material and transflect from it;

whereby the light redirecting material provides diffuse transflectivity of the light energy contacting the material, with greater than 90% of the light energy contacting the material being transflected from it;

placing the light redirecting material next to a second light reflectant material; and

causing light from a light source to pass through the light redirecting material and reflect from the second light reflectant material.

2. The method of claim 1 that further comprises

providing as the light redirecting material a flexible sheet of expanded polytetrafluoroethylene, allowing the light redirecting material to be readily formed into different shapes;

and

forming the light redirecting material to provide a non-planar transflective surface.

3. The method of claim 1 that further comprises

mounting the light redirecting material with a light source on one side of the material;

and

causing light from the light source to diffuse through the light redirecting material to provide an even dispersion of light transmitted through the material.

4. The method of claim 1 that further comprises

causing light from the light source to pass a second time through the light redirecting material after reflecting from the second light reflectant material.

5. The method of claim 1 that further comprises

employing the light redirecting material as a light transflective panel.

6. The method of claim 1 that further comprises

providing a light redirecting material a material that transflects over 95% of the light energy in the range of 250 to 750 nm contacting it.

7. The method of claim 1 that further comprises

providing as the light redirecting material a material that transflects over 99% of the light energy in the range of 250 to 750 nm contacting it.

8. An improved light redirecting material comprising

a transflective material comprising an expanded polytetrafluoroethylene having polymeric nodes interconnected by fibrils defining microporous voids therein, the reflectant material having a diffuse transflectance with greater than 90% of the light contacting the material transflecting away from the material;

a second light reflectant material oriented next to the transflective material such that the second light reflectant material receives light transmitted through the transflective material and reflects light back through the transflective material.

9. The light redirecting material of claim 8 wherein the second light reflectant material is attached to the transflective material.

10. The light redirecting material of claim 9 wherein the second light reflectant material comprises a metal layer attached to the transflective material.

11. The light redirecting material of claim 8 wherein the light redirecting material provides diffuse reflectance of over 90% of the light striking its surface.

12. A method of redirecting light comprising

providing a light redirecting material comprising an expanded polytetrafluoroethylene having polymeric nodes interconnected by fibrils defining microporous voids therein;

mounting the light redirecting material to cause light energy to contact the material and transflect from it;

whereby the light redirecting material provides diffuse transflectivity of the light energy contacting the material, with greater than 90% of the light energy contacting the material being transflected from it; and

providing as the light redirecting material a material that transflect over 95% of the light energy in the range of 250 to 750 nm contacting it.

13. The method of claim 12 that further comprises

providing as the light redirecting material a flexible sheet of expanded polytetrafluoroethylene, allowing the light redirecting material to be readily formed into different shapes;

and

forming the light redirecting material to provide a non-planar transflective surface.

14. The method of claim 12 that further comprises

mounting the light redirecting material with a light source on one side of the material;

and

causing light from the light source to diffuse through the light redirecting material to provide an even dispersion of light transmitted through the material.

15. The method of claim 12 that further comprises

placing the light redirecting material next to a second light reflectant material;

and

causing light from a light source to pass through the light redirecting material and reflect from the second light reflectant material.

16. The method of claim 15 that further comprises

causing light from the light source to pass a second time through the light redirecting material after reflecting from the second light reflectant material.

17. The method of claim 12 that further comprises employing the light redirecting material as a light transflective panel.

18. The met hod of claim 12 that further comprises

providing as the light redirecting material a material that transflects over 99% of the light energy in the range of 250 to 750 nm contacting it.