环保型封端水性聚氨酯的合成

Synthesis of environment friendly waterborne blocked polyurethane

以聚醚多元醇和2,4-甲苯二异氰酸酯(TDI)为基本原料,以异丙醇为稀释剂、亚硫酸氢钠为封端剂,用预聚体—封端混合法,合成了封端型水性聚氨酯。通过讨论异氰酸酯指数R值、预聚温度、预聚时间、封端剂用量、封端温度和封端时间等因素对封端型水性聚氨酯性能的影响,确定R值2.0,预聚反应温度和时间(63℃,2h),封端的温度和时间(0～5℃,30min)以及封端剂的用量(n_(NaHSO_3))/n_(NCO)=2.75)为最佳工艺。

Using polyethylene glycol and 2,4-toluene diisocyanate as the basic raw materials,isopropanol as the diluent and sodium bisulfite as the blocking agent the waterborne blocked polyurethane was synthesized by prepolymer-blocking combined process.Through the discussion about the influence of isocyanate index （R value）,temperature and time of prepolymerization,blocking agent amount,temperature and time of blocking etc.,on the properties of the blocked waterborne polyurethane,the optimal process conditions were determined as follows：R value 2.0,prepolymerization temperature and time 63℃ and 2h,blocking temperature and time 0℃-5℃ and 30 rain,and blocking agent amount （NaHSO4/NCO mole ratio） 1.75.