Preparation And Research Of Lignin Based Coatings Material

Lignin is one of the most abundant renewable natural polymers.It is environmentfriendly,and composed of aromatic rings and a variety of active functional groups.Thus,in recent decades,the lignin was used to prepare coatings,composites,and prepolymer components.In this paper,the application of organosolv lignin in coatings was explored.Organosolv lignin(OL)was used to synthesize organosolv-lignin-based epoxy acrylate(OLBEA)coatings.The reaction process was determined by epoxy and acid values.OLBEA coatings were prepared by dual(Ultraviolet(UV)and thermal)curing to achieve a deep and complete process.The structures of lignin-based epoxy(OLBE)and OLBEA were characterized by Fourier transform infrared spectroscopy(FTIR).The properties of the dualand UV-cured coatings were then compared by measuring gel content and mechanical properties.Results revealed that the dual-cured films had higher cross-linking degree and better mechanical properties than the UV-cured films.The chemical resistance of the dualcured coatings was also examined.The properties of OLBEA coatings obtained by dual curing were shown to be excellent and promising for wide-ranging applications.In addition,polyethylene glycol was partly replaced by organosolv lignin.The organosolv lignin reacted with isocyanate to prepare organosolv lignin-based polyurethane(LPU).Also,it was functioned by the oxidation of ozone,which could break the threedimensional network structure of organosolv lignin and thus promote the active groups in organosolv lignin.The effect of ozonation time and organosolv lignin content on the properties of LPU film was studied.The oxidation time was set as 0 h,0.5 h and 1 h,respectively.The organosolv lignin content applied was 0 %,5 %,10 %,15 % and 20 %,respectively.It was found that the hydroxyl content of ozonized organosolv lignin was increased.The reaction activity,reaction efficiency and reaction degree of lignin with isocyanate was thus increased.Therefore,the crosslinking density of LPU was improved.The active group content of lignin oxidized for 0.5 h was 4.520 mmol/g.The tensile strength of 20 % oxidized lignin(ozonation for 0.5 h)based polyurethane film was 47.2 MPa,which was 174 % higher than that of PU film.Its hardness was increased to be 3H,and the adhesion reached 0 grade.In addition,the water absorption of LPU was lower than that of PU,and LPU had better thermal stability.