| UV-curable waterborne coatings have aroused extensive attention due to the characteristics of environmental protection,energy saving and high efficiency of curing,and have been applied to practical production.However,because of the low degree of crosslinking,UV-curable waterborne coatings are likely to result in poor overall performance of the coatings,which limits the fields of its application.In this thesis,UV-curable monomers containing double carbon-carbon bonds were grafted on the side groups of the acrylic functional prepolymer in order to prepare UV-curable waterborne resins with high content of double carbon-carbon bonds,and the properties of photocurable materials were also studied.Using acrylic acid（AA）,methyl methacrylate（MMA）,n-butyl acrylate（BA）and hydroxyethyl acrylate（HEA）as monomers,and acetone as a solvent,the free radical copolymerization was conducted to obtain a series of functional prepolymer containing hydroxyl and carboxyl groups with different compositions.Differential scanning calorimetry（DSC）was adopted to test the glass transition temperature（Tg）of each functional prepolymer.When the mass ratio of AA,MMA,BA and HEA was1:3:6:6,the Tgof this functional prepolymer was 20.8°C.After neutralization and hydration on the functional prepolymer,a stable emulsion was obtained,proving that the functional prepolymer had a desirable self-emulsifying property.In addition,the functional prepolymer was characterized by Fourier transform infrared spectroscopy（FTIR）and the number average molecular weight of this functional prepolymer was9894 g·mol-1which was measured by gel permeation chromatography（GPC）.And this functional prepolymer was used in subsequent grafting and application research.Using isophorone diisocyanate（IPDI）and HEA as raw materials,a semi-adduct of IPDI-HEA was synthesized under the catalysis of dibutyltin dilaurate（DBTDL）.By titrating the isocyanate value during the reaction,the curve of the degree of the reaction between reaction time was obtained,and the product of the semi-adduct was characterized by FTIR.Different amounts of the UV-curable monomers（IPDI-HEA semi-adduct）were grafted onto the selected functional prepolymer to obtain UV-curable urethane-modified acrylic resin with the grafting rate ranging from 10%to 90%.The structure and the molecular weight of the grafted product was determined by FTIR and GPC.After the product of grafts was neutralized,hydrated and the acetone solvent was removed,a UV-curable waterborne urethane-modified acrylic emulsion was obtained.The particle size and Zeta potential of this emulsion were tested and its stability were investigated.The results showed that the stability of the emulsion decreased with the increase of grafting degree.A photoinitiator was added to the light-cured waterborne urethane-modified acrylic emulsion,and after mixing,drying,and ultraviolet curing,cured films and cured coatings with different double bond contents were obtained.The thermal properties of the cured films were tested and analyzed by DSC and thermal gravity analysis（TG）,and the mechanical properties of the cured films were tested by electronic stretching machine.Also,the pencil hardness,gloss and adhesion were tested on the light-cured coating,and the corrosion resistance of the coating was tested by electrochemical impedance methods,and the surface morphology of the coating was observed by atomic force microscope（AFM）.The experimental results showed that the UV-curable waterborne resin with its grafting degree being 70%had desirable comprehensive performance after curing. |
