Synthesis and Evaluation of Properties of a Novel Cationic Waterborne Polyurethane Finishing Agent

There is a cationic group that makes sure waterborne polyurethane self-emulsify on the main or side chain of cationic waterborne polyurethane (CWPU), which brings excellent function to cationic polyurethane, simultaneously it reduces water resistance. In this research, the good stability of CWPU was prepared as well as the water resistance and softness of cationic waterborne polyurethane film was improved. Elasticity, extensibility, weight gain rate, contact angle, TG, and structure of polyurethane had been tested and evaluated. Also, emulsion stabilities of polyurethane were tested, including storage stability, high-temperature stability, freeze-thaw stability, electrolyte stability, acid stability, and dilution stability; In addition to that, particle size and its distribution were tested. The test showed that the emulsion stability of polyester polyurethane illustrated a good result, while the mechanical property, water resistance, and water repellency were poor. Moreover, mechanical property and water resistance of polyether polyurethane film were good, but high-temperature stability, acid and alkali resistant, and water repellency of emulsion showed poor. For the synthesis of polyurethane, mixed soft segments of polyester (PE2348) and polyether (ZC330) were used, when mass ratio of (PE2348) to (ZC330) is not less than 1, that helped to improve the emulsion stabilities, increased contact angle, decreased particle size. But the water-resistance of film weakened when mass ratios of PE2348 to ZC330 were increased and the mechanical property was poorer. TG showed that thermal stability became poor. The introduction of hydrophilic chain extender (N120) can reduce the water resistance and water repellency of polyurethane. When the mass fraction of N-methyl diethanolamine (MDEA) was about 6% to 7%, the smallest particle size was 61 nm, and the water repellency was larger. The increase of MDEA content would reduce the water-resistance of the film. Finally the effect of hydrophilic chain extender on waterborne polyurethane was studied.