双组分聚氨酯涂料体系是由羟基树脂和多异氰酸酯两个组分发生化学反应而成膜,在汽车修补、工程机械、大巴、轨道列车等领域应用十分广泛。为了获得良好的硬度、耐水、耐溶剂、耐划伤等性能,体系的凝胶化反应是必须的。本文基于Carothers凝肢点理论对双组分聚氨酯体系的化学反应进行了深入分析,重点剖析了羟基树脂组分的官能度对反应体系临界反应程度的影响,以及两个组分的相对用量对体系分子量、交联密度等的影响规律。分析结果对于掌握该体系的成膜机理、优化产品组成具有重要的指导意义。

The two-component polyurethane coating film is formed by the chemical reaction of hydroxyl resin and polyisocyanate,which is widely used in the coating of automobile,engineering machinery,buses,rail trains,etc.In order to obtain good hardness,water resistance,solvent resistance and scratch resistance,the gelation reaction of the system is necessary.Based on the Carothers gel-point theory,the chemical reaction of two-component polyurethane system was deeply analyzed.The influence of the functional degree of hydroxyl resin composition on the critical reaction degree of the system was emphatically analyzed and the influence of the relative dosage of the two components on the molecular weight and crosslinking density of the system was also analyzed.The results are of great importance for the understanding of the film forming mechanism of the system and optimization of the product composition.