Multiwall sheet, an article, a method of making a multiwall sheet
View Patent ↗In one embodiment, a multiwall sheet comprises a first sheet comprising an inner surface and an outer surface, a second sheet comprising a first surface and a second surface; and a rib disposed between the inner surface and the first surface. The outer layer can have surface features and has a surface area of greater than or equal to 140% of a planar, flat, non-profiled surface area for a same unit area.
1. A multiwall sheet comprising:
a first sheet comprising a planar inner surface and an outer surface, wherein the outer surface has surface features and has a surface area of greater than or equal to 140% of a planar, flat, non-profiled surface area for a same unit area;
a second sheet comprising a first surface and a second surface; and
a rib disposed between the inner surface and the first surface;
wherein the multiwall sheet has a normalized thermal insulation value (U) as measured by ISO 10077 of less than or equal to 0.028 W/m·K.
2. The multiwall sheet of claim 1 , wherein the surface feature is a complex shape.
3. The multiwall sheet of claim 1 , wherein the surface features has a graduated, stepped pattern.
4. The multiwall sheet of claim 1 , wherein the surface feature is a complex shape formed by the combination of a triangle and a circle or partial circle.
5. The multiwall sheet of claim 1 , wherein the surface area greater than or equal to 150% of the planar, flat, non-profiled surface area for the same unit area.
6. The multiwall sheet of claim 5 , wherein the surface area is greater than or equal to 225% of the planar, flat, non-profiled surface area for the same unit area.
7. The multiwall sheet of claim 6 , wherein the surface area greater than or equal to 250% of the planar, flat, non-profiled surface area for the same unit area.
8. The multiwall sheet of claim 1 , wherein the normalized linear thermal transmittance value is less than or equal to 0.018 W/m·K.
9. The multiwall sheet of claim 8 , wherein the normalized linear thermal transmittance value is less than or equal to 0.010 W/m·K.
10. The multiwall sheet of claim 9 , wherein the normalized linear thermal transmittance value is less than or equal to 0.001 W/m·K.
11. The multiwall sheet of claim 1 , wherein the second surface comprises surface features.
12. The multiwall sheet of claim 1 , wherein the second surface comprises second surface features, and wherein the second surface features have a second surface area of greater than or equal to 140% of the planar, flat, non-profiled surface area for the same unit area.
13. The article of claim 1 , wherein the rib extends from the inner surface to the first surface.
14. The article of claim 1 , wherein the rib extends between the inner surface and the first surface.
15. A method for forming a multiwall sheet, comprising:
forming a structure comprising
a first sheet comprising a planar inner surface and an outer surface, wherein the outer surface has surface features and has a surface area of greater than or equal to 140% of a planar, flat, non-profiled surface area for a same unit area;
a second sheet comprising a first surface and a second surface; and
a rib disposed between the inner surface and the first surface;
wherein the multiwall sheet has a normalized thermal insulation value (U) as measured by ISO 10077 of less than or equal to 0.028 W/m·K.
16. The method of claim 15 , wherein the forming comprises extrusion.
17. The method of claim 15 , wherein the forming comprises coextrusion.
18. The method of claim 15 , wherein the forming comprises injection molding.
19. The method of claim 15 , wherein the rib extends between the inner surface and the first surface.
20. The method of claim 15 , wherein the rib extends from the inner surface to the first surface.