Environment Friendly UV-cured Coatings Based On Itaconic Acid And Soybean Oil

Recent years have witnessed the increasing consumption of fossil resource and increasing production of environmental pollution with the economic development. Low carbon, energy saving and environmental protection have become the basic requirements for the development of the coatings industry. Using renewable vegetable oils as raw materials and UV cure with high productivity, low energy consumption and extremely low VOC emissions, vegetable oil-based UV curable coatings have attracted great attentions, and there has been some progress. However, acrylated epoxidized soybean oil, as the most reported and used UV-curable vegetable oil-based resins, have bad smell and toxicity from the free acrylic acid.In this thesis, monomethyl itaconate(MMI) was prepared by the esterification of bio-derived itaconic acid and methanol and used to react with epoxized soybean oil to obtain IESO resin with high bio-based content. The coatings were obtained by blending IESO resin with styrene, methyl acrylate, trihydroxymethylpropyl trimethylacrylate(TMPTMA) and UV radiation. Acrylated epoxidized soybean oil(AESO) was used as the control. The main findings are as follows:The optimum conditions of preparation of monomethyl itaconate are as follows: itaconic acid and methanol with molar ratio of 1: 3, 4 wt.% benzoyl chloride, the reaction temperature is 65 oC, reaction time is 0.5h. In this condition, the highest yield is 86.7%. The obtained monomethyl itaconate have a melting point of 68.4 oC and is environmental friendly---no volatilization at room temperature and no VOC emission.The optimum conditions of synthesis of IESO are as follows: monomethyl itaconate and epoxidized soybean oil, 1 wt.% triphenylphosphine as catalyst, 0.2 wt.% hydroxyanisole as polymerization inhibitor, the reaction temperature is 120 oC, and the reaction time is 2 h. Under these conditions, the product containing 2.39 mol double bond per mole of molecule was obtained.The optimum initiator system for pure IESO resin is the complex of 819 and 1173. The elongation at break of the cured samples is about 17.7%, the elastic modulus is about 57.6 MPa, tensile modulus is about 4.95 MPa. The pencil hardness, adhesion, and flexibility are H, 2B, and 0T, respectively. And the surface of the coatings didn’t change after 250 double rubs using methyl ethyl ketone and alcohol. IESO coating exhibits similar properties to the AESO coating cured under the same conditions.The IESO coating comprehensive compared to the AESO coating: using styrene as a reactive diluent, both IESO and AESO coatings showed improved properties, and the IESO/styrene system exhibited better performance than AESO/styrene system; using TMPTMA as a reactive diluent, the properteis of both IESO and AESO coatings was enhanced, and they are close; using methyl acrylate as a reactive diluent, IESO’s performance improved significantly, and AESO’s performance decreased a little.