| Lignin is a kind of renewable resource, which is very abundant in the earth, and can be degraded by biological degradation. It has a large number of hydroxyl groups, mainly existing in the form of phenolic and alcoholic hydroxyl, which can react with many compounds. And thus the lignin based environmental friendly materials can be prepared. Therefore, lignin is considered to be one of the most promising biomass resources in the future. As a UV curable prepolymer, epoxy acrylate has been most widely applied and consumed in the world. It can be fast cured with active diluent, photoinitiator and filler under UV irradiation. Due to its fast curing speed, high adhesion, good wetting with the substrate, excellent chemical and water resistance, epoxy acrylate has been widely applied. Therefore, to apply lignin in the epoxy acrylate to get lignin based bioproduct can endow the obtained materials excellent properties of both lignin and epoxy acrylate. Furthermore, it is also very meaningful to efficiently utilize biomass resources and the environmental protection.In this study, industrial grade lignin was characterized in detail. The industrial grade organosolv lignin was applied as monomer, which could in situ react with the epoxy resin to synthesize the lignin based epoxy(LBE). And further, LBE reacted with acrylic acid to successfully synthesize lignin based epoxy acrylate(LBEA). The characteristic peak of secondary hydroxyl group at 1100 cm-1 on the FTIR curves of LBE proved the phenol hydroxyl group on lignin successfully reacted with the epoxy group by ring-opening esterification, and secondary hydroxyl group was produced. The characteristic peak of epoxy group at 913 cm-1 disappeared and the characteristic peak of ester group at 1730 cm-1 appeared. This proved the acrylic acid successfully reacted with the LBE to produce LBEA. The epoxy value and acidity was characterized, and thereafter, the reaction conditions, such as the reaction temperature and time were explored and optimized.The prepared LBEA oligomer was well mixed with active diluent, photoinitiators and other additives to get the mixture, and the mixture was UV cured. The optimized formulation of the film was obtained by the performance characterization of the coatings. The best formulation was concluded to be as following. The applied ratio of the active diluent was 30 wt%, and it was consisted of equal mass of IBOA and TPGDA. The photoinitiator was the mixture of 819 and TPO, the mass ratio between them was 1:3.And 10wt% of photoinitiator mixture was used. The UV curing time was 60 s. It was shown that, after UV curing, LBEA can be applied in coating, and its comprehensive performance of LBEA curing film is better than that of EA. With the lignin ratio of 10wt% in the prepolymer, the hardness of the film was 3H, the adhesion was 1, and the flexibility was 5mm. The study proved that the lignin based epoxy acrylate oligomer is very promising for the application in the materials field. |
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