Preparation And Properties Of Waterborne Polyurethane/Nano Fillers With Hydroxyl Group

Waterborne polyurethane is dispersed in water,which characteristics includes non-toxic, nonflammable, better adhesion, higher rigidity and do not pollute the environment, et al. So waterborne polyurethane have been widely used in coating, leather, water-based inks, textiles, adhesives, building materials and other fields, and It can also be used as special functional materials. However, compared with solvent-based polyurethane, water-based polyurethane has some disadvange such as bad water resistance, low mechanical properties, low heat resistance ,et al. So in order to improve the whole performance of water-based polyurethane, a high performance WPU was synthesized, and some kinds of hydroxyl-containing nano particles was added to modified the WPU resin.WPU was synthesized from isophorone diisocyanate (IPDI) and polytetrahydrofuran glycol (PTMG), and dimethylol-propionic acid (DMPA), ethylenediamine (EDA) and 1,4-butanediol (BD) was used as Chain extenders. And we studied in the properties of the resin and its films which inflected by the ratio of -NCO/-OH , the amount of DMPA, degree of the neutralization. The results showed that: when the ratio of -NCO/-OH of the prepolymer increased, the film’s hardness increased, its tensile strength increased, but the stability was worse. When -NCO/-OH ratio is too large, it will make water-based polyurethane hard to form film, 1.4 is the suitable value of the ratio of -NCO/-OH in our experiment. DMPA content will affect the appearance of polyurethane resin, also affect its viscosity, mechanical properties and dispersion. When DMPA content increased, the viscosity and dispersion of water-based polyurethane emulsion became better, but water resistance reduced. Emulsion gradually become stable and transparent. When the film’s tensile strength increased, the elongation at break decreased, in our experiment 5% of DMPA content is proved to be the best. In the emulsification process, as the degree of the neutralization increased, the emulsion showed better dispersion and stability increased, but the solid content fall. When the neutralization is too high, it is hardly to form a stable emulsion. In our experiment, the degree of the neutralization is 90-100%.In order to improve the performances of waterborne polyurethane, modified MMT nanocomposite particles was added into the resin we had synthesized. Due to the high surface energy of inorganic nano-MMT, the simple mechanical mixing will make MMT reunited, and limited its effect. Therefore, we used sol-gel method, and TEOS as raw material to modified MMT surface with Silicon dioxide and organically modified by KH550. FT-IR, XRD and other test were used to prove that the modified MMT particles has a larger layer space. By SEM, mechanical testing, TGA, DSC, water testing and other test, the modified MMT particles was founded effective to improve the compatibility of the matrix, and the mechanical performance, water resistance and heat resistance of water-based polyurethane. The tensile strength increased, elongation at break decreased, the thermal decomposition temperature and glass transition temperature increased, and water absorption decreased.In order to increased both reinforcing and toughening effect of the WPU, we used a new type of hydroxyl-containing particles of inorganic nanotubes HNTs. And used KH550, PEG1000, cerium nitrate respectively as the modifier, HNTs inorganic nanotubes were modified by coupling agent, intercalation and surface modification process coordination. A series of WPU/HNTs nano composites were prepared. By FT-IR, XRD, SEM, TG, DSC and mechanical properties tests, we studied the structure, mechanical properties, heat resistance and water resistance of the composite materials. It was showed that the modified particles’dispersion in the resin has been improved, and effectively improve the mechanical properties water resistance and heat resistance of water-based polyurethane. Tensile strength increased, elongation at break increased, the thermal decomposition temperature and glass transition temperature was higher, and thewater absorption decreased.