Hybrid Fire-Retarded Cellulose Materials

Abstract

A method of producing a fire retarded cellulose fiber material composed of both a liquid fire retardant and a powdered fire retardant useful in producing insulation and other such products is provided.

1 . A method of producing a fire-retarded cellulose fiber material, comprising:
 applying a liquid fire retardant composition to a cellulose source material, the liquid fire retardant composition comprising water, phosphoric acid and optionally one or more additional inorganic acids other than phosphoric acid;   allowing the liquid fire retardant composition to permeate into the cellulose source material to form a liquid-permeated cellulose material;   drying the liquid-permeated cellulose material to remove the solvent, wherein an effective amount of the fire-retardant material remains in the cellulose source material, to form a dried, fire-retarded cellulose material;   processing the dried, fire-retarded cellulose material with a powdered fire retardant chemical or chemical composition to produce a reduced size, fiberized fire-retarded cellulose material; and   optionally, removing dust material from the fiberized fire-retarded cellulose material.   
     
     
         2 . The method of  claim 1 , wherein the liquid fire retardant chemical composition consists essentially of water, phosphoric acid, optionally one or more additional inorganic acids other than phosphoric acid, and optionally one or more additives. 
     
     
         3 . The method of  claim 1 , wherein the liquid fire retardant chemical composition consists essentially of water, phosphoric acid, sulfuric acid, and optionally one or more additives. 
     
     
         4 . The method of  claim 1 , wherein the powdered fire retardant chemical is selected from the group consisting of gypsum (dihydrate), Epsom salts (magnesium sulfate heptahydrate), and a combination thereof. 
     
     
         5 . The method of  claim 1 , wherein the reduced size, fiberized fire-retarded cellulose material comprises, based on the total weight of the material,
 80 to 95 wt % cellulose fibers comprising a liquid fire retardant chemical absorbed therein,   2 to 20 wt % powdered fire retardant chemical; and   0 to 0.2 wt % surfactant.   
     
     
         6 . The method of  claim 1 , further comprising, after removing the dust material, adding a powdered fire retardant chemical or chemical composition to the fiberized-fire-retarded cellulose material. 
     
     
         7 . The method of  claim 1 , wherein an amount of the powdered fire retardant chemical or chemical composition is added to the cellulose fiber material to meet at least one of ASTM C-739, EP Category B, and EP Category C. 
     
     
         8 . A method of producing a fire-retarded cellulose fiber material, comprising:
 applying a liquid fire retardant composition to a cellulose source material, the liquid fire retardant composition comprising water, phosphoric acid, and optionally one or more additional inorganic acids other than phosphoric acid;   allowing the liquid fire retardant composition to permeate into the cellulose source material to form a liquid-permeated cellulose material;   drying the liquid-permeated cellulose material to remove the solvent, wherein an effective amount of the fire-retardant material remains in the cellulose source material, to form a dried, fire-retarded cellulose material;   fiberizing the dried, fire-retarded cellulose material to produce a fiberized fire-retarded cellulose material comprising cellulosic dust material comprising the fire retardant absorbed in and adhered to the dust material;   removing a major amount of said cellulosic dust material from the fiberized fire-retarded cellulose material by screening the cellulose fiber material to produce a low-dust, liquid-fire-retarded chemical-treated cellulose fiber material; and   adding a powdered fire retardant chemical or chemical composition to the low-dust, liquid-fire-retarded chemical-treated cellulose fiber material to produce the fire-retarded cellulose fiber material.   
     
     
         9 . The method of  claim 8 , wherein the liquid fire retardant chemical composition consists essentially of water, phosphoric acid, optionally one or more additional inorganic acids other than phosphoric acid, and optionally one or more additives. 
     
     
         10 . The method of  claim 8 , wherein the liquid fire retardant chemical composition consists essentially of water, phosphoric acid, sulfuric acid, and optionally one or more additives. 
     
     
         11 . The method of  claim 8 , wherein the powdered fire retardant chemical is selected from the group consisting of gypsum (dihydrate), Epsom salts (magnesium sulfate heptahydrate), and a combination thereof. 
     
     
         12 . The method of  claim 8 , wherein the fiberized fire-retarded cellulose material comprises, based on the total weight of the material,
 80 to 95 wt % cellulose fibers comprising a liquid fire retardant chemical absorbed therein,   2 to 20 wt % powdered fire retardant chemical; and   0 to 0.2 wt % surfactant.   
     
     
         13 . The method of  claim 8 , wherein an amount of the powdered fire retardant chemical or chemical composition is added to the cellulose fiber material to meet at least one of ASTM C-739, EP Category B, and EP Category C.