Synthesis And Application Of Hyperbranched Polyurethane Oligomers For Ultraviolet Curing Powder Coatings

Ultraviolet(UV) curing powder coatings combined the dual advantages of UV curingcoatings and powder coatings, have the merits of environmental protection, low energyconsumption, high efficiency and excellent quality, so this coatings have been gained moreand more attention since recent years. Some UV curing powder coatings have sold by foreigncompanies such as Cytec, Akzo and Dupont, but we can hardly see these products in domesticmarket because the fall-behind technology and the research is still in the experimentalexploration stage. So it is very important to develop the UV curing powder coatings in orderto break the monopoly of foreign technology and promote domestic environment-friendlypaints to really step to markets.In the dissertation, the new ideal is that increasing the glass translation temperature(Tg)of hyperbranched polyurethane oligomers through changing the central cores, andhyperbranched polyurethane oligomers have been synthesized. On this basis, the coatingformulations have been optimized, and UV curing powder coatings with good performanceshave been obtained. The specific studies are as follows:Solvent polymerization method was used to synthesize hyperbranched polyurethaneoligomers with powder state at room temperature. The Tg of some oligomers were above50℃, the lowest melting temperatures were90℃, so those oligomers were ideal materials ofUV powder coatings with good thermostability. Other assistants were selected by threeprinciples as follows: easily obtain, suitable price, good performances. Designing formulawith Orthogonal experimental table at four factors and three levels; preparation of paints withdrying mixture method; coating the paints with the electrostatic gun; melt leveling under aninfrared light and form the film under UV lamp; testing and assessing the performances offilms. The UV curing powder coatings developed from our experiments were white powdersat room temperature and had good storability, besides the curing temperature could low to90-120℃and combination performances are good, can directly use for middle or highdensity wooden substrates, so the products have great market prospects.