Preparation Of Methylolated Phosphate Flame Retardant And Effect On The Performance Of Treated Wood

Methylolated guanylurea phosphate (DFMP), as one of nitrogen-phosphorous (N-P) flame retardants, has been receiving great attention in both academic and industry fields for their hign-effective flame retardance. However, its poor anti-leaching performance limited the application of N-P fire retardants. In this study, wood was treated with DFMP which were prepared from dicyandiamide(DCD),formaldehyde(F), melamine(M) and phosphoric acid(PA).Various ratios of components were used to systhsize the DFMP flame retardants and then designed to treat wood samples to obtain the optimal formula of DFMP in terms of fire retardance and leaching resistant ability. Furthermore, we attempted to improve the leaching resistance and fire retardance of DFMP by adding MMT or silica sol, as well as combining with thermal modification. The main conclusions are summarized as follows:(1) The optimal formula of DFMP was obtained when the components ratios were DCD:M=5:1,PA:(DCD+M)=1.2:1,F:(DCD+M)=1.5:1. Wood samples treated by this formula showed better anti-leaching ability and fire retardance than other formulas.(2)Thermal-DFMP modified wood showed the reduced leaching, moisture absorption and flame retardance compared to the wood samples treated with DFMP only. However, the smoke release values of DFMP treated wood decreased after thermal modification, and it decreased with the increasing heating temperature.(3) Compared to wood samples treated with DFMP only, Na-MMT/MGUP treated wood samples showedhigher leaching resistance and moisture absorption. However, OMMT/DFMP treated samples exhibited poorer leaching resistance. The flame retardance and smoke suppression of Na-MMT/DFMP treated wood samples were better than those treated by OMMT/DFMP.(4) Compared to wood samples with treated by DFMP only, wood samples treated with Silica sol/DFMP through two steps pressure impregnation showed higner leaching resistance, moisture absorption and better flame retardance, while decreased smoke suppression. However, the efficiency of flame retardance and leaching resistance of wood treated with silica sol/DFMP throgh direct blending process were not improved, but showed better smoke suppression and less moisture absorption.