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

• US 5,982,542 A
• Filed: 08/12/1997
• Issued: 11/09/1999
• Est. Priority Date: 01/06/1995
• Status: Expired due to Term

• Current Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Original Assignee: W. L. Gore & Associates (W.L. Gore & Associates)
• Inventors: Minor, Raymond B., McGregor, Gordon L., Hannon, Gregory E.
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): SIKDER, MOHAMMAD YUNUS
• Application Number:
  US08/910,096
• Time in Patent Office: 819 Days
• Field of Search: 359/599, 359/559, 359/515, 362/341, 526/242, 372/72, 372/98
• US Class Current: 359/559
• 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 a structure of expanded polytetrafluoroethylene having polymeric nodes interconnected by thread like fibrils emerging from the nodes, and 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.

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

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.

5. The method of claim 4 that further comprises

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

6. The method of claim 1 that further comprises

employing the light redirecting material as a light transflective panel.

7. The method of claim 1 that further comprises

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

8. 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.

9. A method of redirecting light comprising

providing a light redirecting material comprising a structure of expanded polytetrafluoroethylene having polymeric nodes interconnected by thread like fibrils emerging from the nodes, and 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 99% of the light energy contacting the material being transflected from it.