Synthesis And Characterization Of High Solid Content Polyurethane Dispersion Containing Carboxylic And Sulfonic Groups

High-solid-content and low-viscosity polyurethane dispersions(PUDs) have broad prospects in application of various fields including as adhesives, coatings, inks and so on. Their usages in leather finishes, textile coatings, plastic films and papers were demanded of excellent performance, such as high pliability, high water resistance and high hydrolytic resistance. This article presents the preparation method of PUD having a high solid content of 50% and low-viscosity by using the acetone method. The PUD was synthesized using polyether polyol containing sulfonate(SPPG), dimethyol dimethyol propionic acid (DMPA) as anionic centers, mixing isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HDI), poly(hexamethylene neopentylene adipate) (PHNA), chain extender with different molecular structure: piperazine, sophorone diamine (IPDA), ethylene diamine(EDA) and hexamethylene diamine (HDA).The effect of different parameters on dispersions'viscosity, particle size, particle size distribution and particle morphology were investigated by laser light scattering particle size analyzer and Transmission Electron Microscope (TEM). The results showed that the particle size decreased with the increasing of hydrophilic group content (HGC), -SO3Na/-COOH and HDI/IPDI molar ratio, but the viscosity increased. Particle size distributions became narrower with increasing of HGC and -SO3Na/-COOH molar ratio which is one of the most important facts effect on the binary distributions. Particle size distributions were not significantly affected by HDI/IPDI moral ratio. TEM showed that PUD particles were inerratic sphericity with more hydrophile, the particles became larger and the anomaly particles increased with decreasing of HGC.PUD Films were tested by mechanical properties, shore A hardness, Dynamic mechanical thermal analysis (DMA) and thermogravimetry analysis(TG). The results of tensile tests showed that the max ultimate elongation of PUD cast film was 2400% and the max elongation strength was 15MPa. Their shore A hardness were between 34.8 and 56.5, most under 40. The PUD films were soft not sticky with comfortable handle. Dynamic mechanical analysis showed that the glass transition temperatures(Tg) of PUD cast films were between -50~-35℃and increased with the increasing of -NCO/-OH. Thermogravimetric analysis indicated that the degradation of PUD cast film started at about 300℃and completely degradation at about 500℃that showed excellent thermal stability.