Fireproofed Materials

materials whose low combustibility results from special treatment (fireproofing). Fire-proofing techniques include coating the materials with a layer of noncombustible or poorly combustible substances and the addition of fire retardants as components of materials to reduce combustibility. The effectiveness of fireproofing coatings containing a binder, filler, and pigment is largely dependent on the physicochemical properties of the coating, as well as on its adhesion to the material being treated. Water glass, lime, vinyl perchloride and carbamide resins, and phosphorobromine organic polymers are commonly used as binders in the preparation of fireproofing coatings. Binders that form a coked, foamed melt upon exposure to fire, thus preventing heating of the material, are promising. Coatings or paints prepared from such binders are called expanding coatings. They are multicomponent systems (usually based on a polymeric binder) and are painted onto the material to be fireproofed, thus functioning as paint and varnish coatings.

Fireproofing coatings are intended mainly to prevent wood and wooden structures from catching fire; expanding coatings can also be used to increase the fire resistance of metal structures and to protect certain polymeric materials. This method of fireproofing also includes the coating of combustible structures with noncombustible facing materials. The fireproofing action of fire retardants added to the prepared material is based on their chemical reaction with the material being treated, resulting in the production of a large quantity of poorly combustible carbon, which stores up a substantial amount of the heat liberated during combustion. The decomposition of certain fire retardants upon exposure to fire is accompanied by the evolution of noncombustible gases, thereby increasing the fireproofing effect. Fire retardants are used to treat wood products, textiles, and certain combustible polymeric materials.

The most effective means for fireproofing (impregnating) wood and cellulose textiles are mixtures of ammonium phosphate and ammonium sulfate, phosphoric acid and dicyanodiamide, and borax and boric acid. Fire-retardant compounds containing chlorine, bromine, phosphorus, and boron mixed with antimony trioxide are added to polymeric materials during their manufacture to retard combustion. This method is used to prepare phenol and polyurethane foam plastics, as well as fiber glass-reinforced plastics manufactured from a relatively noncombustible polyester resin base.