Coating to cool a surface by passive radiative cooling

Patent metadata

Field	Value
Publication number	US-11084944-B2
Application number	US-201916683666-A
Country	US
Kind code	B2
Filing date	Nov 14, 2019
Priority date	Feb 27, 2017
Publication date	Aug 10, 2021
Grant date	Aug 10, 2021

Abstract

Disclosed herein in is a radiative cooling formulation comprising a first component with >55% reflectance in a wavelengths range of 0.3 to 2.5 microns, a second component with >0.85 peak thermal emissivity in a window range of 4 to 35 microns, and a third component to mechanically bind together a mixture of the first and second components.

First claim

What is claimed is:

1. An apparatus comprising:
a radiative cooling formulation comprising:
a first component with >55% reflectance in a wavelengths range of 0.3 to 2.5 microns;
a second component with >0.85 peak thermal emissivity in a window range of 4 to 35 microns; and
a third component to mechanically bind together a mixture of the first and second components.

2. The apparatus of claim 1 , wherein the radiative cooling formulation further comprises a fourth component to protect the first and second components.

3. The apparatus of claim 1 , wherein two or more of the first, second and third components comprise a same material.

4. The apparatus of claim 2 , wherein the second component and the fourth component are the same component.

5. The apparatus of claim 2 , wherein the first component comprises one or more of the following materials: PTFE, barium sulfate, zinc oxides, aluminum oxides, magnesium oxides, TiO 2 .

6. The apparatus of claim 1 , wherein the second component comprises one or more of the following materials: materials with carbon-carbon bonding, PTFE, PFA, FEP, ETFE, THV, ethyl cellulose, poly ethyl methacrylate PEMA, poly methyl methacrylate PMMA, polyvincyl butyrol PVB, cellulose acetate, polyethylene, polypropylene, polyethylene terephthalate PET, polyethylene naphthalate PEN, polyesters, and polycarbonate.

7. The apparatus of claim 1 , wherein the second component is a top coating.

8. The apparatus of claim 1 , wherein the second component comprises one or more of the following materials: PTFE, PFA, FEP, ETFE, THV, ethyl cellulose, poly ethyl methacrylate PEMA, poly methyl methacrylate PMMA, polyvincyl butyrol PVB, cellulose acetate, polyethylene, polypropylene, polyethylene terephthalate PET, polyethylene naphthalate PEN, polyesters, and polycarbonates.

9. The apparatus of claim 2 , wherein the fourth component comprises one or more of the following materials: PTFE, PFA, FEP, ETFE, THV, ethyl cellulose, poly ethyl methacrylate PEMA, poly methyl methacrylate PMMA, polyvincyl butyrol PVB, cellulose acetate, polyethylene, polypropylene, polyethylene terephthalate PET, polyethylene naphthalate PEN, polyesters, and polycarbonates.

10. The apparatus of claim 1 , wherein radiative cooling formulation is comprised of a single layer having the first, second and third components mixed therein.

11. The apparatus of claim 1 , wherein radiative cooling formulation is comprised of a multilayer structure having the first, second and third components mixed therein.

12. The apparatus of claim 2 , wherein the first component has >95% reflectance in the wavelengths range of 0.3 to 2.5 microns.

13. The apparatus of claim 1 , wherein the radiative cooling formulation forms a coating that provides passive radiative cooling greater than zero Watts per square meter (W/m 2 ) without input of water or electricity.

14. The apparatus of claim 1 , wherein the radiative cooling formulation forms a coating that provides a passive radiative cooling of at least 5 degrees Celsius below ambient temperature when solar illumination is present on the apparatus and without input of water or electricity.

15. The apparatus of claim 2 , wherein the fourth component is physically robust but does not decrease radiative flux.

16. The apparatus of claim 2 , wherein at least one of the second component and fourth component is a clear coating that is radioactively emissive in a window range of 4-35 microns, but is substantially non-absorbing of visible wavelengths, such that the optical properties of the surface are largely unchanged by the addition of the clear coat, but the thermal emissivity is enhanced.

17. The apparatus of claim 2 , wherein the second component comprises one or more of the following materials: materials with carbon-carbon bonding, PTFE, PFA, FEP, ETFE, THV, ethyl cellulose, poly ethyl methacrylate PEMA, poly methyl methacrylate PMMA, polyvincyl butyrol PVB, cellulose acetate, polyethylene, polypropylene, polyethylene terephthalate PET, polyethylene naphthalate PEN, polyesters, and polycarbonate.

18. The apparatus of claim 2 , wherein radiative cooling formulation is comprised of a single layer having the first, second and third components mixed therein.

19. The apparatus of claim 2 , wherein radiative cooling formulation is comprised of a multilayer structure having the first, second and third components mixed therein.

20. The apparatus of claim 2 , wherein the radiative cooling formulation forms a coating that provides passive radiative cooling greater than zero Watts per square meter (W/m 2 ) without input of water or electricity.

Assignees

• Palo Alto Res Ct Inc

Inventors

• Van Overmeere Quentin
• Elrod Scott Alan
• Solberg Scott E
• Iftime Gabriel
• Neelakantan Ravi
• Casse Bernard D

Classifications

• C09D7/69

  Particle size larger than 1000 nm · CPC title

• C09D5/004 Primary

  Reflecting paints; Signal paints · CPC title

• C08K2003/3045

  Sulfates · CPC title

• C08K2003/2241

  Titanium dioxide · CPC title

• C09D5/024

  characterised by the additives · CPC title