Methods of conferring fire retardancy to wood and fire-retardant wood products
A process is provided for treating wood products including lumber, plywood and other engineered wood products comprising the steps of applying an aqueous fire-retardant impregnate and applying a coating to the surface of the wood product. In one embodiment, said process confers fire-retardant properties to the wood products sufficient to pass the extended burn test of ASTM E-84. The present invention also provides fire retardant wood products.
1. A method of treating an engineered wood product comprising the steps of:
applying an aqueous fire-retardant impregnate by pressure or vacuum treatment or microwave treatment to an engineered wood product with a thickness of approximately ½ inch in an amount of about 1 to about 4.5 pcf, such that the impregnate penetrates the engineered wood product; and
applying a coating to the engineered wood product surface in an amount of about 0.04 to about 0.11 lbs/ft 2 ;
wherein said coating is an intumescent coating comprising a polymer binder, a source of mineral acid catalyst, a source of carbon, and a source of non-flammable gas; and
wherein said polymer binder is selected from the group consisting of a dispersion of a thermoplastic polymer, a thermosetting polymeric resin, a film forming polymeric resin, an aqueous dispersion of polyamide resins, polyethylene resins, polypropylene resins, polyester resins, polyester resins, vinyl ester resins, vinyl ester ethylene copolymers, acrylic resins, styrene/acrylic copolymers, styrene/butadiene copolymers, synthetic or natural latexes, epoxies and polyurethanes.
2. The method of claim 1 , wherein said coating may incorporate fibrous reinforcements, threads, yarns, and fabrics of both natural and synthetic materials and combinations thereof.
3. The method of claim 2 , wherein said fibrous reinforcements are synthetic fibers.
4. The method of claim 2 , wherein said fibrous reinforcements are glass.
5. The method of claim 2 , wherein said fibrous reinforcements are polyamide.
6. The method of claim 2 , wherein said fibrous reinforcements are graphite.
7. The method of claim 2 , wherein said fibrous reinforcements are natural fibers.
8. The method of claim 2 , wherein said fibrous reinforcements are hemp.
9. The method of claim 2 , wherein said fibrous reinforcements are jute.
10. The method of claim 2 , wherein said fibrous reinforcements are sisal.
11. The method of claim 2 , wherein said fibrous reinforcements are cotton.
12. The method of claim 2 , wherein said fibrous reinforcements are wool.