封闭聚氨酯的制备及其对聚丙烯酸酯的改性

通过合成聚氨酯的预聚体，并成功的用三种苯酚类封闭剂对其封闭，随后用封闭聚氨酯预聚体对聚丙烯酸酯进行改性，得到了水性的环境友好型聚氨酯/聚丙烯酸酯的复合乳液，并对封闭异氰酸预聚体与复合乳胶膜进行了一系列测试：傅里叶红外光谱分析(FTIR)、差示扫描量热法测试(DSC)、热重分析测试(TGA)以及万能力学仪测试.还研究了三种不同苯酚类封闭剂对异氰酸酯的封闭，并通过加入少量的封闭型聚氨酯，对聚丙烯酸酯进行化学交联改性.相对于单一的聚丙烯酸酯膜，得到改性后的复合膜，复合膜的热稳定性、力学性能均得到提高，而且随着聚氨酯含量的增加，膜的抗拉伸强度上升，同时，断裂伸长率有所下降；但增加到一定程度时，过多的聚氨酯会破坏成膜过程，导致膜的性能下降.

Study on blocked polyurethane and its chemical modification of polyacrylate

The prepolymer of polyurethane was synthesized and successfully sealed with three phenolic blocking agents. Subsequently， the polyacrylate was modified with a closed polyurethane prepolymer to obtain an aqueous environment-friendly polyurethane/polyacrylate. The blocked isocyanate prepolymer and composite emulsion was subjected to a series of tests on the composite latex film， Fourier transform infrared spectroscopy (FTIR)， differential scanning calorimetry (DSC)， thermogravimetric analysis (TGA)， and universal material test. In this paper， the blocking of isocyanates by three different phenolic blocking agents was studied， and the polyacrylate was chemically cross-linked by adding a small amount of blocked polyurethane. Compared with a single polyacrylate film， the modified composite film is obtained， and the thermal stability and mechanical properties of the composite film are improved. As the polyurethane content increases， the tensile strength of the film increases， while the elongation at break decreases. However， when it is increased to a certain extent， excessive polyurethane will destroy the film formation process， resulting in a decrease in the performance of the film.