SYNTHESIS AND PROPERTIES OF UV-CURABLE WATERBORNE UNSATURATED POLYESTER FOR WOOD COATING

UV-curable waterborne unsaturated polyesters for wood coatings were pr epared. The effects of different polyols and acids on the properties o f the UV-curable waterborne unsaturated polyesters were investigated. Several different unsaturated polyester prepolymers were prepared from three different polyols [ethylene glycol (EG), diethylene glycol(DEG) , and propylene glycol(PG)] and three different acids [tetrahydrophtha lic anhydride (THPAn), terephthalic acid (TPA), and trimellic anhydrid e (TMAn)]. UV-curable coating materials were formulated from the prepo lymers and 2-hydroxy-2-methylphenyolpropane-1-one as a photoinitiator with distilled water as a diluent. Trimethylolpropane diallyl ether wa s used as an air inhibitor of cure. The dynamic mechanical studies sho wed the properties of those unsaturated polyesters were well correlate d with their glass transition temperature behaviors. It was found that the unsaturated polyester prepared with 60/40 (mol %) TMAn/THPAn and the equimolar mixture of EG, DEG, and PG showed balanced coating prope rties such as good tensile properties and weatherability, as well as p roper viscosity (ca. 2500 cps) when using distilled water as a diluent . (C) 1998 John Wiley & Sons, Inc.