Synthesis And Properties Of Diethylene Bis(Methyl Phosphonate) Flame Retardant

With the development of industrialization,more and more polymer compounds are used in our daily life,so more and more fire hazards are caused.As the society pays more and more attention to the environment,the requirements for flame retardants are more and more stringent.Compared with halogen flame retardants,phosphorus flame retardants,especially organophosphorus flame retardants,meet the requirements of low toxicity,low smoke and high stability.In this paper,a kind of phosphate flame retardant,diethylene bis(methyl phosphonate),was synthesized.Diethylene bis(methyl phosphonate)flame retardants were synthesized by three different synthetic methods,respectively,using ethylene glycol and methyl phosphonate dimethyl ester,dichloroethane and methyl phosphonate dimethyl ester and ethylene glycol and methyl phosphonyl dichloride as reactants.The optimal synthesis conditions were obtained by exploring the reaction conditions.In the first method,when ethylene glycol and dimethyl methylphosphonate were used as reactants,sodium hydroxide was used as catalyst.When the reaction time was 10 h,the reaction temperature was 120?,5% of the amount of dimethyl methylphosphonate was used as catalyst,and when the amount of toluene is 5 times of the total reactant,the optimum synthesis conditions were obtained.In the second method,ethylene glycol and methylphosphonyl dichloride were used as reactants.When the reaction time was5 h,the reaction temperature was 30?,the amount of catalyst was 4% of dimethyl methylphosphonate,and when the amount of toluene is 10 times of the total reactant,the optimum synthesis conditions were obtained.In the third method,the intermediate 1,2-ethylenebis(methoxymethylphosphonate)was synthesized firstly.When the reaction time was 9h,the reaction temperature was 170?,the catalyst was 5% of dimethyl methylphosphonate,and the ratio of dimethyl methylphosphonate to dibromoethane was 3:1.When the reaction time is 9h,the reaction temperature is 120 ?,the amount of catalyst is 5% of dimethyl methylphosphonate,and when the amount of toluene is 5 times of the total reactant,the optimum synthesis conditions are obtained.The intermediate product1,2-ethylenebis(methoxymethylphosphonate)and the target product diethylenebis(methylphosphonate)were qualitatively analyzed by IR,1H NMR and MS.In one-step synthesis,the first method takes a long time,and the second method has a high yield,but the exothermic reaction is difficult to control the temperature,triethylamine hydrochloride is easy to be produced,and the amount of toluene solvent is large.The two-step synthesis of diethylene bis(methyl phosphonate)has high yield,but the two-step reaction time is long,and many factors need to be considered.The synthesis of diethylene bis(methyl phosphonate)is the best way to synthesize diethylene bis(methyl phosphonate)with ethylene glycol and dimethyl methyl phosphonate as reactants.Limiting oxygen index(LOI),vertical combustion test,cone calorimetry,thermogravimetric analysis(TGA)and tensile properties of the synthesized flame retardant were tested.When the amount of flame retardant is 30%,the LOI value is32.2,and the combustion grade reaches V-0.With the increase of the amount of flame retardant,the amount of carbon residue increased,the heat release decreased,the flame retardancy was better,but the tensile properties decreased.