Flame Retardants
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Borates are being used in various materials (timber, cellulosic insulation, PVC and textiles) as flame retardant. Boron suppresses the fire by covering the surface of the material and cutting off the contact with oxygen. Zinc borate is used in plastic materials, easily soluble borates such as boric acid, borax pentahydrate and borax decahydrate are used in the cellulosic materials. These materials are natural fibers like wood, plywood, wood fiber, paper and cotton.
In cellulosic insulation, borax pentahydrate and boric acid are used. These products are used to increase the energy efficiency, to prevent the growth of fungi and other microorganisms and to increase the resistance of the material against flammability.
Zinc borate, barium metaborate, boron phosphate and ammonium fluoborate are the main boron compounds used for the flame-retardancy of PVC. HCl is exposed to air during the combustion of PVC. When zinc borate is added as flame retardant to the PVC, this gas reacts with the non-volatile zinc and boron compounds and prevents the release of hazardous gases.
Although borax and boric acid are useful flame retardants in textile industry, problems can be encountered as they can easily be washed out from the textile product.
Disodium octaborate tetrahydrate can successfully be used for long-term protection of wood from fungi and insects. This material can easily be applied to timber by spraying, painting or applying pressure without taking any special precaution.
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