Synthesis And Properties Of UV-curable Waterborne Polyurethane

UV-curing water-based polyurethane has advantages of UV-curing coatings and water-based paint. More and more attention are paid to its outstanding environmental protection, energy saving and fast curing and other advantages. UV-curing coatings for self-emulsifying emulsion without emulsifiers get better benefits. Currently the system of UV-curing water-based polyurethane is mainly through the preparation and the synthesis of single-hydroxyl-terminated ethers of acrylic monomers. But the adoption of such a method to introduce the performed polymer will limited contents of double bond. In this study subjects, Glycidyl methacrylate (GMA) modified UV-curable waterborne polyurethane emulsion was prepared by using Polybutyleneglycol adipate, Hexanedioic acid, polymer with 1,4-butanediol (PBA2000), Toluene diisocyanate (TDI), Dimethylolpropionic acid (DMPA), 2-Hydroxyethyl acrylate (HEA, glycidyl methacrylate (GMA) as the main materials. It can form the stable UV-curable waterborne polyurethane emulsion after the neutralization with triethylamine. One advantage of GMA with the main chain carboxyl group introduced in response to DMPA may be the introduction of more available UV-curing of the double bond, so that cross-linked branching point of adding more to form a mesh structure with improved performance and to improve the pure water-based polyurethane poor water hardness and weaknesses to gain a UV-curable waterborne polyurethane with good emulsion stability and excellent comprehensive properties.The GMA-modified UV-curable waterborne polyurethane studies have shown:(1) The optimum temperature of GMA grafting reaction is 70℃. (2) With the increased use of DMPA to obtain the polymer, hard segment content increased. And coulomb force between molecules and hydrogen bonds increased. The film hardness and water resistance deteriorated. Therefore, DMPA use is between the 1.3%.(3) With the n (-NCO):n (-OH) increased, water resistance decreased. Therefore, n (-NCO):n (-OH) as the best is between the 1.5-1.6. (4) As the molar ratio of GMA and the DMPA gets larger and larger, cross-linking degree of polymers increased. And hardness is also greatly improved with the stability of the variation. The best molar ratio is between 0.5-0.6.(5)if it has photoinitiator concentration of 3% emulsion quality and UV-curing time of 40 seconds, this system gets the best speed of UV-curing.