Application of water-borne polyurethane/polyvinyl alcohol composite surface sizing agent in the specialty paper

The anionic waterborne polyurethane emulsion was successfully prepared by the reaction of polycaprolactone diols(PCL),toluene diisocyanate(TDI),dimethylolpropionic acid(DMPA).A series of waterborne polyurethane/polyvinyl alcohol compound latex were synthesized by polyurethane,polyvinyl alcohol and aziridine as crosslinker.The results show that the compound emulsion owns excellent sizing property when m(WPU)=75%.The papers' folding endurance can reach 1 025 times,paper stiffness reach 72.1mN,the dry and wet tensile strength respectively reach 162.3,57.4N,sizing value reach 97 s.The polymer was characterized with FT-IR,DLS and TG.