Synthesis And Application Of Phosphine Oxide-based Phosphonate Flame Retardants

Polymer materials are widely used in national life,and the demand is increasing.However,polymer materials are flammable,which would cause huge property loss and casualties in case of fire.Therefore,it is necessary to flame retardant modify.phosphorus flame retardant has become hot research topics due to their halogen-free and high efficiency.Among them,phosphonate flame retardant has good thermal stability,water resistance and solvent resistance advantages due to its structure with P-C-O bond.However,phosphonate flame retardant has poor charring ability,which reduces the flame retardant effect.Therefore,it is necessary to introduce flame retardant element that can form char,into the structure of phosphonate flame retardant.In this paper,tris(hydroxymethyl)phosphine oxide(hereinafter referred to as THPO)and phosphoric acid(hereinafter referred to as PI)were used as raw materials to prepare intermediate(hereinafter referred to as THPO-PI)through esterification reaction;then,THPO-PI reacted with ammonia or ethylene glycol to synthesize phosphonate ammonium salt flame retardant(hereinafter referred to as THPO-PI-A)and polyhydroxy phosphonate flame retardant(hereinafter referred to as THPO-PI-EG).The synthesis conditions were optimized and the application of flame retardant polyurethane PU was studied.The main research contents were included as follows:(1)Intermediate THPO-PI was synthesized by the reaction of THPO and PI as raw materials.Through single factor experiments,the optimal reaction conditions were obtained as follows:reaction temperature was 140?,n(THPO):n(PI)=1:3,rotating speed was 150r/min,THPO dropping time was1h,reaction time was 3h after dropping.Under the optimal reaction conditions,the yield of THPO-PI was 93.78%.The product was characterized by FT-IR and NMR spectroscopy,which proved that the synthesized product was the target product THPO-PI.(2)Flame retardants THPO-PI-A and THPO-PI-EG were synthesized by reacting THPO-PI with ammonia and ethylene glycol respectively.The effects of various experimental factors on THPO-PI-A and THPO-PI-EG were studied,and the optimal reaction conditions were obtained by single factor experiment.Under the optimal reaction conditions of the experiment,the yield of THPO-PI-A was 64.5%,and the yield of THPO-PI-EG was 77.57%.The products were characterized by FT-IR and NMR spectroscopy,which proved that the synthesized products were the target products THPO-PI-A and THPO-PI-EG.The thermal properties were characterized by TG,The results shownd that the residual carbon content and thermal stability of THPO-PI-A were better than THPO-PI-EG.(3)Flame retardant polyurethane foam were prepared by One-step method,by using polyether polyols R4110,isocyanate PM200 and alcohol solution A33 of bicyclo(2.2.2)-1,4-diazaoctane as the main raw materials,as well as introducing foaming agent,stabilizer M8805 and flame retardant(THPO-PI-A or THPO-PI-EG),.Compared with pure PU,the LOI of flame retardant PU added with THPO-PI-EG increased significantly,and the flame retardant level was reached to nonflammable when the addition amount was 15wt%,and HRR,THR,SPR and CO₂production amount of CONE are significantly lower.However,the combustion time was shorter,and UL94 of flame-retardant PU added with THPO-PI-EG was unchange,meanwhile,the flame-retardant PUwas more easily deformed;Compared with pure PU,When THPO-PI-A was added in 5wt%,UL94 of the flame retardant PU reached the V-0 level,and the shape of the flame retardant PU was unchange;The LOI of flame retardant PU reached to nonflammable level when addition amount was 10wt%;HRR,THR,SPR and CO₂production amount of CONE test were obviously reduced when addition amount was 20wt%,among which,PHRR was reduced by 66%,and the ignition time was delayed from 11s to 147s.