Method of forming transparent heat mirrors on polymeric substrates

• US 4,248,687 A
• Filed: 07/23/1979
• Issued: 02/03/1981
• Est. Priority Date: 07/23/1979
• Status: Expired due to Term

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Fan, John C. C.
• Primary Examiner(s): Weisstuch, Aaron
• Application Number:
  US06/059,794
• Time in Patent Office: 561 Days
• Field of Search: 204/192 P, 427/109, 427/160, 427/164, 427/166, 428/411, 428/480, 428/539
• US Class Current: 204/192.11
• CPC Class Codes: B29D 11/00596 Mirrors
• CPC Class Codes: C23C 14/0021 Reactive sputtering or evaporation
• CPC Class Codes: C23C 14/0036 Reactive sputtering
• CPC Class Codes: F24S 80/52 characterised by the material for preventing heat loss F24S80/56
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]

Abstract

Transparent heat-mirrors are disclosed which are formed from tin-doped indium oxide films or antimony-doped tin oxide films deposited onto polymeric substrates. Low temperature deposition processes, such as ion-beam sputtering, are employed to preserve the polymeric substrates, and films having high transparency to visible radiation and high reflectivity to infrared radiation are deposited on the polymeric substrates by carefully controlling the partial pressure of oxygen during deposition.

Claims

1. In the method of fabricating transparent heat-mirrors including deposition of films of a material selected from doped indium oxide or doped tin oxide on polymer substrates by sputtering, thermal evaporation, vacuum deposition or electron bombardment, the improvement of maintaining a partial pressure of oxygen during deposition within a range which produces films of said material which are transparent to the visible solar spectrum and reflecting to the infrared spectrum without necessary post-deposition treatment.

2. The improvement of claim 1 wherein said material comprises tin-doped indium oxide or antimony-doped tin oxide.

3. The improvement of claim 2 wherein said range of partial pressure of oxygen during deposition is within the range from about 1×

10^-5 to about 6×

10^-5 Torr.

4. In a process for depositing tin-doped indium oxide or antimony-doped tin oxide films into polymeric substrates to produce transparent heat-mirrors by sputtering, thermal evaporation, vacuum deposition or electron bombardment:

the improvement of controlling the partial pressure of oxygen during said deposition process to between about 1×

10^-5 Torr and about 6×

10^-5 Torr.

6. A method of claim 4 wherein the bombarding ions comprise argon ions.

7. A method of claim 6 wherein said target source comprises a mixture of indium oxide and tin oxide or tin.

8. A method of claim 7 wherein said polymeric substrate comprises a polymeric film.

9. A method of claim 8 wherein said polymeric film comprises a film of polyethylene terephthalate.

5. An ion-beam sputtering process for producing transparent heat-mirrors, comprising:

a. providing a target source of indium oxide and tin in an ion-beam sputtering chamber;

b. mounting a polymeric substrate at a location within said ion-beam sputtering chamber where deposition of tin-doped indium oxide occurs;

c. bombarding said target source with ions sufficient to cause ejection of indium oxide and tin atoms from said target source; and

d. controlling the partial pressure of oxygen within said sputtering chamber during deposition to a level of between about 1×

10^-5 Torr and about 6×

10^-5 Torr.

10. In a process for depositing tin-doped indium oxide or antimony-doped tin oxide onto polymeric substrates by sputtering, thermal evaporation, vacuum deposition or electron bombardment:

the improvement of controlling the partial pressure of oxygen during said deposition process to a value of below about 5×

10^-5 Torr.