Study On The Synthesis Of Novel Phosphorus-containing Flame Retardants

Organic polymeric materials have been widely used in various fields in society due to their great properties.However,most organic polymeric materials are easy to combust.Moreover,organic polymeric materials have a large heat release rate in the combustion process and readily drop molten droplets and release flue gas,which has an adverse impact on economic and social development and human life and health.As a new type of organic phosphorus-containing flame retardant,alkylphosphinates are halogen-free,environmentally friendly,hydrophobic and have high flame-retardant efficiency,and have little impact on the properties of material.Therefore,alkylphosphinates have great prospects for development.In this paper,the synthetic routes of dialkylphosphinates under atmospheric pressure are explored,aiming to reduce the synthesis cost of dialkylphosphinates,to increase the safety and environmental friendliness of the production process,and to make it suitable for large-scale industrial production.Firstly,the synthetic route of diethylphosphinate under atmospheric pressure is studied in this paper.Sodium diethylphosphinate is synthesized by free-radical addition and reacts with different inorganic metal salts to obtain metal salts of diethylphosphinates.Six metal salts of diethylphosphinates containing different metal ions are synthesized.The total yields of aluminum diethylphosphinate,zinc diethylphosphinate,ferric diethylphosphinate,chromic diethylphosphinate,manganese diethylphosphinate and cobalt diethylphosphinate are 71.3%,52.9%,74.9%,56.4%,3.3% and 7.8%,respectively.The effects of reaction time and the p H of solution on the yield of aluminum diethylphosphinate are discussed.Except for manganese diethylphosphinate and cobalt diethylphosphinate,other products all show excellent thermal stability.Secondly,the reaction route of synthesizing aluminum dioctylphosphinate by free-radical addition under atmospheric pressure is explored.The effects of the molar ratio of reactants,reaction time,reaction temperature and the amount of initiator on the yield of sodium dioctylphosphinate are investigated.The optimum reaction conditions are as follows: in the first step,acetic acid as solvent,n(1-octene):n(sodium hypophosphite)= 2.5:1,reaction time = 16 h,reaction temperature = 105 ℃,and the amount of benzoyl peroxide = 6%,the yield of sodium dioctylphosphinate is 78.8%.In the second step,the mixed solvent of ethanol and water(ethanol/water = 1:1)as solvent,reaction temperature = 60 ℃,reaction time = 2 h,the yield of aluminum dioctylphosphinate reaches 96.1%.The total yield of two-step reaction of aluminum dioctylphosphinate is 75.7%.The temperatures of 5% weight loss of aluminum dioctylphosphinate is 349 ℃,indicating the great thermal stability of the product.In addition,the synthetic route of aluminum didecylphosphinate by free-radical addition under atmospheric pressure is also investigated.When acetic acid is used as solvent,the molar ratio of 1-decene to sodium hypophosphite is 2.5:1,the reaction time is 16 h,the reaction temperature is 105 ℃,and the amount of benzoyl peroxide is 6%,the yield of sodium didecylphosphinate is 75.6%.In the second step,when the mixed solvent of tetrahydrofuran and water(tetrahydrofuran/water = 1:1)is used as the solvent,the reaction temperature is 60 ℃and the reaction time is 2 h,the yield of aluminum didecylphosphinate reaches 90.9%.The total yield of two-step reaction of aluminum didecylphosphinate is 68.7%.The temperatures of 5%weight loss of aluminum didecylphosphinate is 294 ℃.