Synthesis and effect factors of waterborne polyurethane with high solid content based on polyether polyols

With isophorone diisocyanate(IPDI) and hexamethylene diisocyanate(HDI) as hard chain segment, polyether polyols(N-220) as soft chain segment,dimethylol propionic acid(DMPA) as hydrotropic substance, ethylenediamine as chain extender and tri(hydroxymethyl)propane(TMP) as cross linker,the waterborne polyure-thanes (WPU) with high solid content based on polyether polyols were synthesized. The WPU’s structure was charac terized by ATR,the influences of content of solvent(acetone) and DMPA,thin or thick of prepolymer in reaction process,charging sequence and reaction time of chain extender were discussed on solid content of WPU. The experiment results showed if systems was thin(namely viscosity was lower)in the process of prepolymer reaction, according to first adding ethylenediamine,then reaction about 4-7 min,finally adding water,so stable WPU emulsion with high solid content (namely 40%-46%) based on polyether polyols was easily prepared when other conditions was invariable,namely molar ratio of -NCO to -OH was 1.2∶1,mass ratio of HDI to IPDI was 2∶1,molar ratio of -OH in TMP to -OH in polyether polyols was 1∶4,mass fraction of DMPA was 1.5% in resin and mass fraction of acetone was 50.4%-75.5% in resin.