Synthesis of cationic water-based polyurethane emulsion modified by epoxy resin and its strengthening effect of surface treatment for paper
A series of cationic water-based polyurethane emulsion modified by epoxy resin were successfully prepared by in situ polymerization using isophorone isocyanate(IPDI),hexamethylene-1,6-diisocyanate(HDI) and polycaprolactone diols(PCL1000),then epoxy resin(E-44) were introduced for crosslink modification.Fourier transform infared spectrometer(FT-IR) were used to characterize the structure of the polymer.Medium resistance,mechanical properties and water contact angle of the cast films were also measured.Effects of E-44 content on the properties of polymer and sizing performance were investigated.The surface of the paper before and after treatments were observed by scanning electron microscope(SEM).The results show that the emulsion and sizing performance were excellent when n(NCO)/n(OH)=1.3,m(MDEA)=10%,m(E-44)=12%.At the same time,the papers sizing value can reach 78s,and wet strength approaches 39%,folding endurance 57 times.With the increase of E-44 content,the water absorption of the film decreased from 13.69% to 6.46%,toluene absorption from 121.5% to 74.8%,the contact angle of the film increased from 64.85° to 116.49°,as well as the mechanical strength increased.
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维普
