| The consciousness toward environmental care and the efforts of governmentalorganizations are limiting the amount of volatile organic compounds (VOCs) releasedin the atmosphere, organic solvent-based polyurethanes (PUs) are increasingly beingrestricted. Seeking a kind of environmentally friendly water-based polyurethaneproducts is very important. The drying process of WPUs was influenced by the highheat of water vaporization and relative humidity. Compared to conventionalsolvent-borne PU, the shortcoming of WPUs is its inferior drying rates. All of thesehas limited the development and application of WPU. It has great significance andprospects to develop novel WPU with fast drying rate.In this paper, a series of WPUs were prepared by means of the prepolymerdispersion method, polycarbonate diols (PCDL), polycaprolactone glycol(PCL) andpolytetrametlylene glycol (PTMG) had been used as soft segments,4,4′-dicyclohex-ylmethane diisocyanate (HMDI), hexamethylene diisocyanate (HDI)and isophorone diisocyanate (IPDI) were used as hard segments, dimethylolbutanoicacid (DMBA),1,4-butanediol(BDO) and triethylamine (TEA) were used ashydrophilicthe chain extender, chain extender and neutralizing agent, respectively.The L9(34) orthogonal experiment method was adopted in the course ofchoosing the better process conditions and formulations in theexperiments. The result showed: when polycarbonate diols is as the soft segments,4,4-dicyclohexylmethane diisocyanate and hexamethylene diisocyanate (the mix ratioof1.77) are as the hard segments and dimethylolbutanoic acid is4%, the waterbornepolyurethane had the highest drying rate, its volatizing rate constant was0.99.The single factor experiments show: while solid content is36%, hard segmentcontent is43%, R value is1.05, neutralization degree is100%, at same time ionicgroups has been located soft segments, the dispersion had the highest drying rate, its volatizing rate constant was1.23, tensile strength was3.23MPa，elongation at breakwas167%，shear strength was0.59MPa，water swell was16.28%. |
