Vapor Phase Boric Acid Treatments for Cotton Batting To Meet U.S. Mattress Flammability Standard Ff 4-72

Abstract

The U.S. Mattress Flammability Standard FF 4-72 imple mented in December 1973 requires that mattresses resist ignition by lighted cigarettes placed on the bare mattress surfaces at specified loca tions, as well as similar tests where the cigarettes are placed between two sheets. This standard, while implying flammability, really measures resist ance of cotton mattresses to the initiation of smoldering combustion. Smoldering combustion is defined as a slow oxidation directly from the solid phase. Phosphorus containing flame retardants that impart excellent glow resistance in the context of open flame tests are inadequate to pre vent smoldering combustion in mattresses. Boric acid, although not con sidered an efficient or effective flame retardant, when applied to cotton batting yields products that will pass FF 4-72. Current processes for the treatment of cotton batting with boric acid utilize immersion-padding, spray, or dry powder techniques. These processes require either large amounts of energy or excessive chemical add-on. A process employing methanol and boric acid, which readily forms volatile methyl borate at ambient temperature, has been developed. This process takes advantage of the hydrolysis of methyl borate to boric acid when the vapors contact moisture within and on the cotton, as shown by the following reaction: