Abstract: The effects of covering NaOH and Na2SiO3 solution on the flame retardant properties of medium density fiberboard were investigated based on the techniques of chamber combustion method, the vertical combustion apparatus and limit oxygen index.The results show that various flame retardant performance of fiberboard are follows: fiberboard covered Na2SiO3 > NaOH + Na2SiO3 > NaOH > untreated fiberboard > bubble water treatment, the single-side pasting presented a higher flame retardant performance than the double-side pasting, the limit oxygen index could reach 25.2%.It is proposed the flame retardant mechanism of NaOH and Na2SiO3 on the medium density fiberboard, coating NaOH solution makes the flame retardant substances migrate out the surface, coating Na2SiO3 is benefit to form a cross-linking siliceous layer containing (=)Si-O-Si(=) chains, leading to an improvement of the flame retardant performance.

Key words: fiberboard;flame retardant;Na2SiO3;oxygen index;chamber combustion