Synthesis And Properties Of Linoleic Acid Based Fast UV-curable Coatings

Due to the scarcity of petrochemical raw materials, the replacement of petroleum-based polymeric materials by bio-based ones has gained growing industrial and academical interests. Conventional coatings are highly dependent on petroleum-based resources and the cure rate of them are not fast enough. In order to solve these two shortcomings, this paper based on renewable plant-based resources, choose linoleic acid which was extracted from agricultural byproducts as raw material, prepared the linoleic based unsaturated branching linoleic ester oligomer which could fast cured under UV radiation through a series of reactions. Meanwhile, coatings were also prepared. This results could not only achieve the high efficient use of agricultural by-products, replace petroleum-based resources to some extent, while the prepared coatings could be quickly cured under ultraviolet light, effectively increasing the cure rate and scope of application of the coatings.The main contents are as follows:Linoleic acid and glycidyl methacrylate (GMA) were used to synthesize the methacrylated linoleic acid, which was further applied for the reactions with maleic anhydride (MA), GMA. The synthesis process were studied and the results showed that the optimum reaction process of epoxy ring opening esterification was:reaction temperature 130℃, reaction time 3h, molar ratio 1:1.2 (GMA excess). MAH optimal synthesis process for the esterification was:reaction temperature 85℃, reaction time 3h, molar ratio 1:1.The chemical structure of unsaturated branching linoleic ester was characterized by FTIR and 1H NMR. The results showed that the synthesized product having a desired structure, the polyunsaturated linoleic acid ester-modified target product which has a branched structure has been synthesized successfully.In the preparation of coatings stage, the effect of curing solutions on UV cured coatings were studied. The results showed that the optimum UV irradiation distance was 20cm, the optimum thickness was 200μm. Meanwhile the effect of the type and amount of photo initiators and reactive diluents on the cured coatings were also studied. The best cured coating formulation are:modified linoleyl ester:reactive diluent (TMPTA): photo initiator (907)= 54wt%:40wt%:6wt%.The results show that the modified unsaturated branching linoleic ester coatings which were prepared through optimum solutions exhibited fast cure rate, the coatings can fast cure within 7 s under UV irradiation, the C=C double bond conversion of cured coatings reached 93%. Meanwhile the prepared coating exhibit good properties:the adhesion of cured coatings were 1 level, the pencil hardness of cured coatings were 3H, impact strength of cured coatings reached 40 kg · cm as well as excellent water resistance and solvent resistance.