The Study Of Low VOC Content Anionic Or Anionic And Nonionic Waterborne Sodium Bisulfite-Blocked Polyurethane

Sodium bisulfite-blocked polyurethane is one kind of very important thermal-reactive functional polymers and has been of great important application value because of its deblocking reaction under low temperature. But during the preparation, plenty of organic cosolvent is needed to solve the homogeneous reaction problem between sodium bisulfite solution and isocyanate groups in the polyurethane, leading to the increasing of production cost and VOC content.Anionic waterborne sodium bisulfite blocked polyurethane and anionic and nonionic waterborne sodium bisulfite blocked polyurethane with high blocked ratio (more than 90%) were prepared using isophorone diisocyanate (IPDI) and polyether polyol as the main materials; dimethylolpropionic acid (DMPA) and poly (ethylene glycol) methyl ether (PEG-ME) as the hydrophilic modification monomers and sodium bisulfate as blocking agent, without using any organic cosolvent.The products were characterized by FTIR and DSC. The effect of synthesis technology and formula on the property was studied systematically; discuss the effect of R value, prepolymerization conditions, kinds and content of hydrophilic monomers, and studied the effect of blocking reaction conditions, NaHSO3 content and its solution concentration, filling type and promoters on the blocking reaction. The blocked polyurethane products were applied in the crossing modification of waterborne emulsion 2240. When the content is 5%-10%, the tensile property was improved by 4 times, and the absorption and expansion against toluene were reduced by 40.4% and 23.9%; the absorption and expansion against ethyl acetate were reduced by 102.9% and 52.2%; the absorption and expansion against alcohol were reduced by 194.1 and 139.4%.