Studies on syntheses and properties of waterborne polyurethane from castor oil

Waterborne polyurethane(WPU) was prepared by the reaction of castor oil(C.O.) with dimethoxypropionic acid(DMPA) and toluene diisocyanate(TDI).The effects of molar ratios of —NCO to —OH and DMPA content on the properties were investigated.The result showed that the castor oil based waterborne polyurethane had excellent film-forming property,high hardness,excellent fallibility and good resistances to water.The best experiment conditions were as follows:molar ratio of n(—NCO)/n(—OH) was 2.2,DMPA content was 7.0 %,the temperatures of reaction and emulsification stage were 70 and 30 ℃,respectively.