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从聚氨酯预聚体分离游离的二异氰酸酯的方法有许多种,最好的方法是使用薄膜蒸发器进行分离。采用内冷凝式薄膜蒸发器和二次蒸馏技术研究了从甲苯二异氰酸酯(TDI)/三羟甲基丙烷(TMP)型聚氨酯预聚体分离游离TDI的方法及影响TDI分离的主要因素。研究工作通过使用MD-S80内冷式薄膜蒸发器,并调整蒸馏温度和真空度使产物中游离TDI低于0 5%。相应的蒸馏参数是:原料流速1 0kg/h,原料Ⅰ温度100℃,原料Ⅱ温度110℃,一次蒸馏温度150℃,二次蒸馏温度200℃,第一次蒸馏余压5000Pa,二次蒸馏余压35Pa;刮板转动速度150r/min。二次蒸馏后用醋酸丁酯稀释成质量分数为75%的溶液。预聚体中TDI质量分数为0 4%。异氰酸基含量高于12 7%,达到了分离的目标。结果表明内冷式薄膜蒸发器进行二次蒸馏有效地从TDI TMP预聚体分离了游离的TDI。
There are many ways to separate the free diisocyanate from the polyurethane prepolymer. The best method is to use a thin-film evaporator for separation. The method of separating free TDI from toluene diisocyanate (TDI) / trimethylolpropane (TMP) polyurethane prepolymer and the main factors influencing the TDI separation were studied by internal condensation film evaporator and secondary distillation. Research work by using the MD-S80 internal cooling thin film evaporator, and adjust the distillation temperature and vacuum to make the product free TDI less than 0 5%. The corresponding distillation parameters are: raw material flow rate 100kg / h, raw material temperature 100 ℃, raw material temperature 110 ℃, the first distillation temperature 150 ℃, the second distillation temperature 200 ℃, the first distillation pressure 5000Pa, the second distillation Pressure 35Pa; scraper rotation speed 150r / min. After secondary distillation with butyl acetate diluted to a mass fraction of 75% solution. TDI prepolymer mass fraction of 0 4%. Isocyanato content higher than 12 7%, to achieve the goal of separation. The results show that the internal distillation of the thin film evaporator for secondary distillation effectively separates the free TDI from the TDI TMP prepolymer.