包覆赤磷制备工艺及其热安定性研究

Preparation technique of microcapsulated red phosphorus and its thermostability

为了降低赤磷的吸湿性,提高其热安定性,该文采用氢氧化铝-密胺树脂包覆赤磷(MRP)。通过单因素实验优化了制备包覆赤磷的工艺,采用傅里叶变换红外(FTIR)光谱仪和扫描电子显微镜(SEM)对包覆层进行了表征,用热重-差热分析法(TG-DTA)分析了包覆前后赤磷样品的热安定性。结果表明,制备包覆赤磷的最佳工艺参数为,九水合硝酸铝的质量为0.10 g,甲醛和三聚氰胺总质量为0.40 g、摩尔比为3∶1,反应温度为80℃,反应时间为1 h。在此工艺条件下,包覆赤磷(MRP)的吸湿率降幅最大,达到96.88%,且包覆物质量分数小于5%,包覆材料在赤磷表面的包覆状况良好。相比于未包覆赤磷,包覆后赤磷的外推起始温度、峰值温度和外推终点温度分别提高42.8℃、51.7℃和48.4℃;自发火温度提高58.8℃,表明包覆赤磷的热安定性大幅提高。

In order to reduce the hygroscopicity of red phosphorus and improve its thermostability, the aluminium hydroxide/melamine-formaldehyde resin microcapsulated red phosphorus （ MRP ） is successfully prepared. The process of preparing the coated red phosphorus is optimized by the single factor test. The coating layer of the red phosphorus is characterized by the Fourier transform infrared （FTIR） spectrometer and the scanning electron microscopy （ SEM ）. The thermostability of the red phosphorus （ RP） and the MRP is investigated by the thermogravimetric analysis-differential thermal analysis（TG-DTA） in air atmosphere. Results show that the optimal process parameters for preparing the coated red phosphorus are,the mass of the aluminum nitrate nonahydrate 0. 10 g,the total mass of the formaldehyde and melamine 0. 40 g,the molar ratio of the formaldehyde and the melamine 3 ： 1 , the reaction temperature 80 °C , the reaction time 1 h. Under these optimal process parameters, the moisture absorption ratio of MRP reduces 96. 88% （the greatest reduction） ,the mass fraction of coating materials is below 5% ,and the coating materials on the surface of the red phosphorus are in good con-ditions. Compared with the RP,the initial temperture,the peak temperture and the end temperature of the MRP reaction increase 42.8 °C,51. 7 °C and 48. 4 °C respectively, and the autoignition temperature of the MRP increases 58. 8 °C ,indicating that the thermostability of the MRP is superior to that of the RP.