水性聚氨酯的相转变过程

以二异氰酸酯、聚醚二元醇和二羟甲基丙酸(DMPA)合成了自乳化型水性聚氨酯(WBPU),利用其在乳化过程中一些物化性质--电导率和粘度的改变,研究了它的相转变过程,并建立了三阶段结构模型(TSSM),对相转变过程进行模拟.结果显示:自乳化型水性聚氨酯的相转变点发生在水油比为0.175左右,相转变过程分为三个阶段,可以用三阶段结构模型对相转变过程进行模拟.羧基含量、不同分子量的聚醚、R值(NCO/OH摩尔比),都会对相转变过程造成影响.羧基含量一般控制在1.4 wt%左右较好,R值的大小则需根据实际要求选用,一般控制在0.95～1.0范围内.

Phase Transition Process of Water-Borne Polyurethane

Water-borne polyurethane (WBPU) of self-emulsification was synthesized by diisocyanate, polyether, and dimethylol propionic acid (DMPA). Changes in some of its physical and chemical properties (viscosity and conductivity) in the emulsification process were used to study its phase transition process. Further more, a three-stage structure model (TSSM) was used to model phase transition process of WBPU. The following conclusions have been obtained: The point of phase transition of WBPU is (0.175) (ratio of weights between water and oil). Phase transition process can be divided into three stages. It is reasonable to model the phase transition process of WBPU with TSSM. The phase transition process is affected by the content of carboxyl, different molecular weight of polyether, and the value of R. When the content of carboxyl is approximately 1.4 wt%, perfect properties of water-borne polyurethane can be obtained. The value of NCO/OH (R) should be selected according to specific situations.