SOLAR CONTROL FILM
The invention relates to a solar control film comprising at least one infrared reflecting layer comprising a metal and at least one infrared absorbing layer comprising nanoparticles. The infrared absorbing layer is thereby located further from the sun than the infrared reflecting layer. By combining first reflection of the infrared energy and then absorption of the infrared energy, an optimum between reflection and absorption is obtained.
1 . A solar control film positioned relative to the sun, said solar control film comprising
at least one infrared reflecting layer comprising at least one metal;
at least one infrared absorbing layer comprising nanoparticles, whereby said infrared absorbing layer is located further from the sun than said infrared reflecting layer;
said nanoparticles are chosen to have an internal transmission of the infrared absorbing layer in the near infrared range (ranging from 780 nm to 2500 nm) lower than 30% and to have an internal transmission of the infrared absorbing layer in the visible range (ranging from 380 to 780 nm) is higher than 80%.
2 . A solar control film according to claim 1 , whereby the internal transmission of the infrared absorbing layer in the near infrared range (ranging from 780 nm to 2500 nm) is lower than 20% and the internal transmission in the visible range is higher than 90%.
3 . A solar control film according to claim 1 , whereby said nanoparticles are selected from the group consisting of hexaboride nanoparticles, tungsten oxide nanoparticles, composite tungsten oxide particles and combinations thereof.
4 . A solar control film according to claim 1 , whereby said infrared reflecting layer comprises at least one metal selected from the group consisting of silver, gold, copper, chromium and alloys thereof.
5 . A solar control film according to claim 1 , whereby said infrared reflecting layer has a thickness ranging between 5 and 25 nm.
6 . A solar control film according to claim 1 , whereby said infrared reflecting layer is deposited by sputtering or evaporation.
7 . A solar control film according to claim 1 , whereby said infrared reflecting layer is sandwiched between layers having a high refractive index.
8 . A solar control film according to claim 1 , whereby said nanoparticles have a diameter ranging between 1 and 500 nm.
9 . A solar control film according to claim 1 , whereby the concentration of said nanoparticles is ranging between 0.01 and 5 g/m 2 .
10 . A solar control film according to claim 1 , whereby said infrared reflecting and/or said infrared absorbing layer is/are deposited on a flexible or rigid substrate.