Uv Curing Of Water-based High-branched Polyester Preparation And Performance

Hyperbranched polyesters with linear structure were synthesized from trimellitic anhydride(TMA), epichlorohydrin(ECH), methyl tetrahydrophenyl anhydride(MTHPA) and ethanol. Elemental reactions of the polymerization indicated that the two ring opening reactions of carboxyl group and hydroxyl group with epoxy and anhydride respectively, proceeded smoothly under mild condition of polymerization. Glycidyl methacrylate (GMA) was successfully introduced into the hyperbranched polyesters through the reaction of the epoxy group with carboxyl group of resin.The structure and properties of the polyesters were characterized by 1H-NMR, FTIR, GPC, rotating viscometery and DSC. The apparent molecular weights of polyesters were in the range of 2000-3500g/mol, depending on the ratio and feeding manners of monomers. Glass transition temperatures of the polyesters were decreased after introduction of MTHPA and ethanol as the linear units. The unique structures and properties were not changed. It is easily to modify these resins for using as UV curable polyester.The effect of the chemical structure of end-groups, photo initiator and co-monomer concentration and atmosphere on the UV curing kinetics of these hyperbranched polyesters was studied by Photo-DSC. Experimental results had revealed that the chemical structures of end-groups had strongly effects on UV curing kinetics while atmosphere had micro effect. The linear units do not decrease the reactivity of hyperbranched polyesters.The properties of cured films of the water dispersed UV curable coatings were characterized by hardness, impact resistance and resistance to water and acid. Results had revealed that the lowerviscosity, higher UV curing rate and final double bonds conversion of hyperbanched polyesters indicated that the hyperbanched polyester based UV curable water dispersed coatings are practicably useable.