Authors: Li Qingxi, Kong Xia, Zhu Yan'an, Qu Quanqing (School of Chemistry and Chemical Engineering, South China University of Technology; Carpoly Chemical Group Co., Ltd.)  
Abstract: By aminating dimethylolpropionic acid (DMPA) and using it as a hydrophilic chain extender, a polyurethane aqueous dispersion (PUD) free of N-methylpyrrolidone (NMP) and organotin was successfully prepared. The effects of the amination process on PUD preparation and emulsion properties were studied, and the film structure and properties were characterized. Results show:  
(1). The DMPA amination process can avoid the use of NMP and organotin catalysts, producing organotin-free and NMP-free waterborne polyurethane dispersions;  
(2). The waterborne polyurethane film properties from the amination process, especially water resistance and chemical resistance, are superior to those of PUD from organotin-catalyzed processes;  
(3). The process is simple and environmentally friendly.  
(Source: Proceedings of the 2012 Waterborne Polyurethane Industry Annual Conference)