Angular and spectrally selective shading sheet
The present invention relates to a sheet for coating a glass surface having both shading and spectrally selective features in a single foil or film. The present invention relates also to an insulated glazing unit having a glass surface comprising the sheet having both shading and spectrally selective features in a single foil or film.
1. A sheet for application on a glass surface comprising:
at least one polymeric film substrate;
spectrally selective shading means, wherein said spectrally selective shading means comprise one or more optically selective layers coating on a first side of said at least one polymeric film substrate, wherein said one or more optically selective layers have an average T % below 60% across the wavelengths range between 740 nm to 2500 nm; and
angular selective shading means, wherein said angular selective shading means comprise shading elements and wherein said angular selective shading means comprise a micro structured system comprising said shading elements, wherein said shading elements are elongated elements having an extension t and a thickness a and an aspect ratio t/a of at least 1, and further comprising
bonding means, bonding said shading elements to a second side of said at least one polymeric film substrate and wherein said bonding means comprise one or more adhesive layers between said second side of said at least one polymeric film substrate and said shading elements.
2. A sheet for application on a glass surface according to claim 1 , wherein said bonding means comprise one or more adhesive layers embedding said shading elements.
3. A sheet for application on a glass surface according to claim 1 , further comprising at least one optical layer covering one or more surfaces of said shading elements.
4. A sheet for application on a glass surface according to claim 1 , wherein said at least one polymeric film substrate has an average Transmittance (T %) above 70% at wavelengths between 380 nm to 740 nm.
5. A sheet for application on a glass surface according to claim 1 , wherein said at least one polymeric film substrate comprises a polyurethane based film substrate, or a cellulose based film substrate or a polyethylene or a polypropylene based film substrate.
6. A sheet for application on a glass surface according to claim 1 , wherein said at least one polymeric film substrate is coated with a layer of IR absorbing or reflecting nano particles.
7. A sheet for application on a glass surface according to claim 6 , wherein said layer of IR absorbing or reflecting nano particles comprises LaB 6 .
8. A sheet for application on a glass surface according to claim 6 , wherein said layer of IR absorbing or reflecting nano particles comprises TiN.
9. A sheet for application on a glass surface according to claim 6 , wherein said layer of IR absorbing or reflecting nano particles comprises Cs 0.32 WO 3 .
10. A sheet for application on a glass surface according to claim 1 , wherein said one or more optically selective layers comprise one or more barrier layers for protecting one or more metal layers.
11. A sheet for application on a glass surface according to claim 1 , wherein said one or more optically selective layers comprise one or more chemical diffusion barrier layers.
12. A sheet for application on a glass surface according to claim 1 , wherein said at least one polymeric film substrate coated on said first side by said one or more optically selective layers has an average T % above 40% at wavelengths between 380 nm to 740 nm.
13. A sheet for application on a glass surface according to claim 1 , wherein said elongated elements have an aspect ratio t/a of at least 2.
14. A sheet for application on a glass surface according to claim 13 , wherein said elongated elements have a predetermined extension t and are spaced from each other by a predetermined value L, thereby the cut-off angle of the incident solar radiation onto a coated glass surface is 70° or less.
15. A sheet for application on a glass surface according to claim 14 , wherein said elongated elements are spaced from each other by a predetermined value L equal or higher than 250 μm.
16. A sheet for application on a glass surface according to claim 1 , wherein said elongated elements have a predetermined thickness a equal or lower than 150 μm.
17. An insulated glazing unit (IGU) comprising:
one or more glass lites;
and said sheet according to claim 1 .
18. A sheet for application on a glass surface according to claim 1 , wherein said at least one polymeric film substrate has a thickness between μm and 100 μm.