Multilayer plastic structure having low energy transmission
View Patent ↗A multilayer structure comprising a base layer comprising at least one transparent thermoplastic and a specific inorganic infra-red absorber as well as an IR-reflecting multi-ply layer, the production of such a multilayer structure and the use thereof for the production of glazing made of plastic in buildings, automobiles, rail vehicles and aircraft.
1. A multilayer structure, wherein said multilayer structure comprises:
at least one base layer comprising at least one transparent thermoplastic and 0.038 wt. % to 0.5 wt. % of nanoparticles based on indium tin oxide (ITO) and/or antimony-doped tin oxide, based on the total weight of plastics for the base layer, as an IR absorber, wherein the base layer does not comprise a metal boride as an IR absorber and wherein the layer thickness of said base layer is at least 500 nm, and
at least one multi-ply layer which reflects IR radiation and has different plastics and different refractive indices in the layers directly adjacent to one another,
wherein the transparent thermoplastic in the base layer is a polycarbonate or a copolycarbonate, and wherein the multilayer structure has an intrinsic color corresponding to a neutral grey having an a* value of a*=0±4 and b*=0±4, and wherein the multilayer structure has a transmission of more than 70% in the visible wavelength range and a T TS value of less than 60%.
2. The multilayer structure according to claim 1 , wherein said multi-ply layer is a layer produced from an optical interference film.
3. The multilayer structure according to claim 1 , wherein said multi-ply layer is one in which the refractive indices of the layers directly adjacent to one another differ from one another by at least 0.03.
4. The multilayer structure according to claim 1 , wherein said multi-ply layer has at least 10 layers comprising different refractive indices.
5. The multilayer structure according to claim 1 , wherein the individual layers of the multi-ply layer have a layer thickness of from 30 to 500 nm.
6. The multilayer structure according to claim 1 , wherein said multilayer structure comprises nanoparticles based on indium tin oxide (ITO) and/or antimony-doped tin oxide in the base layer in an amount of from 0.063 to 0.15 wt. %, based on the total weight of plastics for the base layer.
7. The multilayer structure according to claim 1 , wherein said nanoparticles based on indium tin oxide (ITO) and/or antimony-doped tin oxide have an average particle diameter of less than 200 nm.
8. The multilayer structure according to claim 1 , wherein said multilayer structure comprise at least one scratch-resistant coating on a side of the base layer and/or on a side of the multi-ply layer.
9. The multilayer structure according to claim 8 , wherein said base layer and/or the scratch-resistant coating comprise at least one UV absorber.
10. The multilayer structure according to claim 1 , wherein said base layer has an IR transmittance of not more than 20% in the wavelength range of from 1200 to 2300 nm and the multi-ply layer reflects 30% of the IR radiation in the wavelength range of from 850 to 1800 nm.
11. A process for producing a multilayer structure according to claim 1 , comprising:
A) preparing a plastics composition comprising at least one transparent thermoplastic, nanoparticles based on indium tin oxide (ITO) and/or antimony-doped tin oxide,
B) producing a substrate of plastic by extrusion or injection moulding from a composition obtained under A),
C) applying a multi-ply film using an adhesive and/or by lamination to the substrate of plastic obtained under B).
12. The process according to claim 11 , further comprising:
D) applying at least one scratch-resistant coating to one or both outer sides of a product obtained under C).
13. A multilayer structure according to claim 1 , which is capable of being used for producing glazing made of plastic in one or more of buildings, automobiles, rail vehicles and/or aircraft.
14. A glazing comprising plastic used in one or more of buildings, automobiles, rail vehicles and aircraft, said glazing comprising at least one multilayer structure according to claim 1 .
15. The multilayer structure according to claim 1 , wherein the individual layers of the multi-ply layer have a layer thickness of from 50 to 400 nm.
16. The multilayer structure according to claim 1 , wherein said multilayer structure comprises nanoparticles based on indium tin oxide (ITO) and/or antimony-doped tin oxide in the base layer in an amount of from 0.050 to 0.250 wt. % based on the total weight of plastics for the base layer.
17. The multilayer structure according to claim 1 , wherein said nanoparticles based on indium tin oxide (ITO) and/or antimony-doped tin oxide have an average particle diameter of less than 100 nm.
18. The multilayer structure according to claim 1 , wherein said base layer has an IR transmittance of not more than 20% in the wavelength range of from 1400 to 2300 nm, and the multi-ply layer reflects 30% of the IR radiation in the wavelength range of from 850 to 1500 nm.
19. The multilayer structure according to claim 1 , wherein the multilayer structure has a transmission of more than 70% in the visible wavelength range and a T Ts value of less than 56%.