Radiative cooling device and cooling method
A radiative cooling device that is in a state in which a radiative surface is colored is provided. A radiative cooling device CP includes an infrared radiative layer A that radiates infrared light IR from a radiative surface H, a light reflective layer B that is disposed on the side opposite to the radiative surface H with respect to the infrared radiative layer A, and a color portion X. The infrared radiative layer A is a resin material layer J that has a thickness adjusted so as to emit a heat radiation energy greater than an absorbed solar energy in a wavelength range from 8 μm to 14 μm, and the color portion X contains a colorant that absorbs light in the visible range.
1. A radiative cooling device comprising:
an infrared radiative layer configured to radiate infrared light from a radiative surface;
a light reflective layer disposed on a side opposite to the radiative surface with respect to the infrared radiative layer; and
a color portion,
wherein the infrared radiative layer is a resin material layer that has a thickness adjusted so as to emit a heat radiation energy greater than an absorbed solar energy in a wavelength range from 8 μm to 14 μm, and
wherein the color portion contains a colorant that absorbs light in the visible range.
2. The radiative cooling device according to claim 1 ,
wherein the colorant has an absorption peak of visible light in a wavelength range from 350 nm to 850 nm.
3. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer is selected from resin materials that have any one or two or more of a carbon-fluorine bond, a siloxane bond, a carbon-chlorine bond, a carbon-oxygen bond, an ether bond, an ester bond, and a benzene ring.
4. The radiative cooling device according to claim 1 ,
wherein a resin material forming the resin material layer contains at least one selected from a vinyl chloride resin, a vinylidene chloride resin, polyvinyl fluoride, polyvinylidene fluoride, a polymethyl methacrylate resin, a resin that contains siloxane as a main component, a fluorocarbon resin, silicone rubber, and a silicone resin.
5. The radiative cooling device according to claim 1 ,
wherein the light reflective layer is silver or a silver alloy.
6. The radiative cooling device according to claim 1 , further comprising:
a protective layer that is disposed between the resin material layer and the light reflective layer, and
wherein the protective layer comprises at least one of a polyolefin based resin, an ethylene terephthalate resin, and an acrylic resin.
7. The radiative cooling device according to claim 6 , further comprising:
a joining layer that joins the protective layer and the resin material layer, and
wherein the joining layer comprises at least one of a urethane resin, an acrylic resin, and an ethylene vinyl acetate resin.
8. The radiative cooling device according to claim 7 ,
wherein the color portion constitutes a portion of the joining layer or the entire joining layer.
9. The radiative cooling device according to claim 7 ,
wherein the color portion is a layer that is provided between the joining layer and the protective layer or between the joining layer and the resin material layer.
10. The radiative cooling device according to claim 1 ,
wherein the color portion is a layer that is disposed on the same side as the radiative surface with respect to the infrared radiative layer.
11. The radiative cooling device according to claim 1 ,
wherein the color portion constitutes a portion of the infrared radiative layer or the entire infrared radiative layer.
12. The radiative cooling device according to claim 1 ,
wherein the colorant contains at least one selected from an azo compound, a quinone compound, a triarylmethane compound, a cyanine compound, a phthalocyanine compound, an indigo compound, and a porphyrin compound.
13. The radiative cooling device according to claim 1 ,
wherein a colorant content that is a value calculated by dividing a total amount of the colorant contained in the color portion by an area of the entire radiative surface is less than 0.1185 g/m 2 .
14. The radiative cooling device according to claim 1 , further comprising:
a hard coat layer at an outermost position on a side opposite to the light reflective layer with respect to the infrared radiative layer.
15. The radiative cooling device according to claim 14 ,
wherein the hard coat layer comprises an acrylic resin.
16. A cooling method performed using the radiative cooling device according to claim 1 , the cooling method comprising:
disposing the radiative cooling device such that the radiative surface of the infrared radiative layer faces the sky; and
allowing the radiative surface to radiate infrared light.