Flame retarding of wood by chemical modification with bromate-bromide solutions

In spite of the extensive and diversified uses of wood and wood products for millenia, there are still a number of basic deficiencies of these products which limit their use and pose difficult and as yet not satisfactorily solved problems to the engineer and consumer. The most prominent of these problems are: flammability, dimensional stability, and fungal attack. Review of work carried out at the Israel Fiber Institute indicates that treating solid timber and polywood with acidified bromate-bromide solutions is capable of overcoming these deficiencies to a large extent. The treatment is carried out in autoclaves with application of vacuum and pressure. The lignin component of the wood is brominated in the solid state by the treatment solution with a high yield of bromine. The mechanical properties of the treated products are unchanged. The treatment is stable to prolonged leaching, aging, and storage. Water absorption and swelling are drastically decreased-dimensional stabilization. The brominated products are shown not to be attacked by wood fungi.