Polyisocyanurate coverboards with improved fire resistance

Abstract

A construction board comprising a foam body having first and second planar surfaces, said foam body including a polyisocyanurate foam matrix defining a plurality of closed cells, said closed cells being at least substantially devoid of hydrocarbon blowing agents, and said foam body being characterized by a density, pursuant to ASTM C303, of at least 2.5 lbs/ft 3 ; and a facer disposed on a planar surface of said foam body, said facer including a glass substrate having an internal planar surface proximate to said foam body and an external planar surface opposite said foam body, a first coating disposed on said external surface, and a second coating disposed on or proximate to said internal surface, where said first coating disposed on said external surface includes an inert filler, and where said second coating disposed on or proximate to said internal surface includes intumescent material.

What is claimed is: 
     
         1 . A construction board comprising:
 a foam body having first and second planar surfaces, said foam body including a polyisocyanurate foam matrix defining a plurality of closed cells, said closed cells being at least substantially devoid of hydrocarbon blowing agents, and said foam body being characterized by a density, pursuant to ASTM C303, of at least 2.5 lbs/ft 3 ; and   a facer disposed on a planar surface of said foam body, said facer including a glass substrate having an internal planar surface proximate to said foam body and an external planar surface opposite said foam body, a first coating disposed on said external surface, and a second coating disposed on or proximate to said internal surface, where said first coating disposed on said external surface includes an inert filler, and where said second coating disposed on or proximate to said internal surface includes intumescent material.   
     
     
         2 . The construction board of  claim 1 , where said inert filler includes calcium carbonate. 
     
     
         3 . The construction board of  claim 1 , where said intumescent material includes expandable graphite. 
     
     
         4 . The construction board of  claim 1 , where said first coating includes a polymeric binder in which said inert filler is dispersed. 
     
     
         5 . The construction board of  claim 1 , where said second coating includes a polymeric binder in which said intumescent material is dispersed. 
     
     
         6 . The construction board of  claim 1 , where said closed cells include carbon dioxide, air, or a partial vacuum. 
     
     
         7 . The construction board of  claim 1 , where said closed cells include less than 2 percent by volume hydrocarbon blowing agent. 
     
     
         8 . The construction board of  claim 1 , where said facer is a first facer, and where said construction board includes a second facer disposed on a planar surface of said foam body opposite said first facer, said second facer including a glass substrate having an internal planar surface proximate to said foam body and an external planar surface opposite said foam body, a first coating disposed on said external surface, and a second coating disposed on or proximate to said internal surface, where said first coating disposed on said external surface includes an inert filler, and where said second coating disposed on or proximate to said internal surface includes intumescent material.