水性聚氨酯的制备及其交联膜的性能研究

采用ＮａＨＳＯ３封端法制备了一系列的水性聚氨基甲酰磺酸钠（ＰＣＳ），讨论了作为溶剂的水、乙酸乙酯、乙醇的用量对封端率的影响，结果表明３种溶剂的用量均有一最佳值，膜的吸水、吸乙醇及动力学实验表明经多乙烯多胺交联的ＰＣＳ膜具有良好的耐水、耐乙醇性能及力学性能。

THE PREPARATION OF WATERBORNE POLYURETHANE AND THE PROPERTIES OF THE CROSSLINKED FILMS

In this paper, the waterborne polyurethane was prepared by blocking method. The title poly(cabamoyl sulfonates) (PCS) with different content of -SO - 3were prepared by blocking reaction of aqueous NaHSO 3 with two series of polyisocyanates and using ethyl acetate, ethanol and water as cosolvents. The two series of polyisocyanates (PU2 and PU3E) were prepared by the reaction of HDI with poly(propylene diol) or poly(propylene-ethylene oxide triol ) respectively. The influnce of the amount of these cosolvents on blocking efficiency was investigated. The results suggested that the optimum weight ratio of ethyl acetate or water to prepolymer was 0.25, 0.2 respectively,and that of ethanol to ethyl acetate was 2.0. The transparent casting films were obtained by crosslinking reaction of aqueous PCS with polyethylene polyamine. The resistance of films to water and ethanol increases with the decrease of the NCO% of prepolymer. The films produced from two types of prepolymer (PU2 and PU3E) should be different responding behavior of swelling and dissolving in water or in ethanol to the NCO% changing because of the different hydrophilicity of the polyethers in PU2 and PU3E. The investigation of casting films indicated that the tensile strength and Young's modulus increased and the elongation at break decreased, with the ratio of NCO/OH increased. It was the result that the crosslinking density of films increased with the increase of NCO% of prepolymer.But, the tensile strength and Young's modulus of films descended when the ratio of NCO/OH was greater than 2.0 because the molecular weight of prepolymer descended and the content of residual HDI increased in that case. The fragility or low mechanical property was brought by the excessive urethane produced by the reaction of these prepolymer of low molecularweight and residual HDI with polyethylene polyamine. The optimum mechanical property of two series of films were obtained when the ratio of NCO/OH was 2.0.