Synthesis And Application Of Resins For UV Curing Powder Coatings

UV curable powder coatingss was a new environment friendly coating with many peculiarities e.g. free solvent formulation, low energy consuming , coating process in so low temperature, high curing speed and productivity. Hyperbranched polymers being the main resin in UV curable powder coatingss is serials of new-style compound macromolecule, which contain high functional groups, spherical shape, the segmental mobility and geometry of the repeating unit so that they have received considerable attention in the resent decade due to their low viscidity, good intersolubility and activity in favor of improving fluidity, reducing the VOC and advancing properties of coating.In this paper, we present new hyperbranched aliphatic polyesters with Trimethanol propane , pentaerythritol, ethoxylated pentaerytritol as different cores were respectively synthesized in the molten state with 2,2-bis(hydroxymethyl)propionic acid and by using p-Toluenesulfonic acid catalysis. The synthesis procedure was a pseudo-one-step reaction where stoichiometric amounts corresponding to each generation were added successively. The polyesters with hydroxyl groups as terminal groups were glassy solids at room temperature. The chemical structure and properties of these polymers were characterized by ¹³C NMR,FI-IR,GPC,DSC. Each polymers were further modified by methacrylic acid and stearic acid-methacrylic acid to form hyperbranched polymers terminated in methacrylic and stearic acid groups partially. The modified hyperbranched resins above-mentioned were applied to UV curable powder coatings , then cured by ifrared lamp and ultra-violet lamp to form films. The properties of films were analysed by flexibility test, pencil hardness test, impact resistance test, adhesion test. In conclusion, the second generation resin with pentaerythritol as a core have high pencil hardness of 4H, and the third generation resin with PP50 as a core process impact resistance of 35Kg/cm, pencil hardness of 4H, adhesion of 1-2 grade with clean and smooth surface, which could be used as main resin in UV-curable powder because of its Comprehensive Performance.