Flame retardant vapor retarding membranes

1. A flame retardant vapor retarding membrane, comprising

a building material substrate sheet having a melt viscosity of about 1 Pa·s to about 1000 Pa·s at measured at 300° C. and 1 rad/s, the building material substrate sheet being a non-woven fabric or a perforated sheet; and

a polymeric coating layer coated on the substrate sheet, the polymeric coating layer having a melt viscosity of about 1 Pa·s to about 1000 Pa·s measured at 300° C. and 1 rad/s, wherein the polymeric coating layer includes a continuous organic phase, with a particulate hydrophilic inorganic filler dispersed therein in an amount of about 10 wt % to about 70 wt %, the particulate hydrophilic inorganic filler being aluminum trihydrate, kaolin, expandable graphite or a combination thereof, the continuous organic phase comprising a hydrophobic polymer in an amount of at least about 70 wt %, based on the total weight of the continuous organic phase of the polymeric coating layer.

2. The flame retardant vapor retarding membrane of claim 1 , configured to have a water vapor permeance of no more than about 2.5 Perm at 25% relative humidity, as tested by ASTM E96 at 23° C., and having a thickness in the range of 5 microns to 1000 microns.

3. The flame retardant vapor retarding membrane of claim 2 , configured to have a water vapor permeance of at least about 5 Perms at 95% relative humidity, as tested by ASTM E96 at 23° C.

4. The flame retardant vapor retarding membrane of claim 1 , wherein the building material substrate sheet comprises polypropylene, nylon, poly(ethylene terephthalate), another polyester or copolyester, polystyrene, acrylonitrile/butadiene/styrene copolymer, or polyethylene.

5. The flame retardant vapor retarding membrane of claim 1 , wherein the building material substrate sheet has a melt viscosity of about 10 Pa·s to about 1000 Pa·s, measured at 300° C. and 1 rad/s, and the polymeric coating layer has a melt viscosity of about 10 Pa·s to about 1000 Pa·s, measured at 300° C. and 1 rad/s.

6. The flame retardant vapor retarding membrane of claim 1 , wherein the hydrophobic polymer is a styrene butadiene copolymer, an acrylic polymer or copolymer, a vinyl acetate/ethylene copolymer, a poly(vinylidene chloride) polymer or copolymer, a poly(vinyl butyral), a polyolefin, or a combination thereof.

7. The flame retardant vapor retarding membrane of claim 1 , wherein the hydrophobic polymer is coated onto the substrate sheet from an aqueous dispersion of the hydrophobic polymer dispersed in water or from an aqueous emulsion of the hydrophobic polymer.

8. The flame retardant vapor retarding membrane of claim 1 , wherein the continuous organic phase further includes a polymeric hydrophilic component in an amount up to about 30 wt %.

9. The flame retardant vapor retarding membrane of claim 1 , wherein the continuous organic phase further includes a lower molecular weight organic material having a melt viscosity less than or equal to the melt viscosity of the hydrophobic polymer, in an amount up to 15 wt % of the continuous organic phase.

10. The flame retardant vapor retarding membrane of claim 1 , wherein the particulate filler has a median particle size of about 2 to about 10 μm.

11. The flame retardant vapor retarding membrane of claim 1 , wherein the particulate filler is aluminum trihydrate, kaolin or a combination thereof.

12. The flame retardant vapor retarding membrane of claim 1 , wherein the combined content of the particulate filler and the hydrophobic polymer is at least about 80% by weight of the polymeric coating layer.

13. A method for making a flame retardant vapor membrane of claim 1 , the method comprising

providing the building material substrate sheet; and

coating the polymeric coating layer onto the substrate sheet.

14. The method of claim 13 , wherein coating the polymeric coating layer onto the substrate sheet includes providing a coating liquid comprising the hydrophobic polymer dispersed in a volatile liquid; coating the coating liquid onto the substrate sheet; and allowing the coated liquid to cure by drying to provide the polymeric coating layer.

15. The method of claim 14 , wherein the volatile liquid is water.

16. The method of claim 14 , wherein the hydrophobic polymer is present in the coating liquid in the form of a polymer dispersion or a polymer emulsion.

17. The flame retardant vapor retarding membrane of claim 1 , wherein the particulate hydrophilic inorganic filler is 15-50 wt % kaolin and 50-85 wt % alumina trihydrate.

18. The flame retardant vapor retarding membrane of claim 1 , wherein the building material substrate sheet has a melt viscosity of about 20 Pa·s to about 500 Pa·s, measured at 300° C. and 1 rad/s, and the polymeric coating layer has a melt viscosity of about 20 Pa·s to about 500 Pa·s, measured at 300° C. and 1 rad/s.

19. The flame retardant vapor retarding membrane of claim 1 , wherein the polymeric coating layer comprises less than about 1 wt % of polymeric hydrophilic components.

20. The flame retardant vapor retarding membrane of claim 1 , configured to have a water vapor permeance of no more than about 2.5 Perm at 25% relative humidity and a water vapor permeance of at least about 5 Perms at 95% relative humidity, as tested by ASTM E96 at 23 °C., wherein the building material substrate sheet comprises polypropylene, nylon, poly(ethylene terephthalate), another polyester or copolyester, polystyrene, acrylonitrile/butadiene/styrene copolymer, or polyethylene.

21. The flame retardant vapor retarding membrane of claim 20 , wherein the building material substrate sheet has a melt viscosity of about 10Pa·s to about 1000Pa·s, measured at 300°C. and 1rad/s, and the polymeric coating layer has a melt viscosity of about 10 Pa·s to about 1000Pa·s, measured at 300 °C. and 1 rad/s.

22. The flame retardant vapor retarding membrane of claim 21 , having a thickness in the range of 5 microns to 1000 microns.