Research Of Polyurethane Acrylates Synthesis And Preparation Of UV-curable Coating

Polyurethane acrylate is one of the important oligomers of UV-curable coating. Theoligomer was synthesized with diisocyanate, glycol or polyols, hydroxyl ethyl acrylate. Thereare ether bond and ammonia ester bond in the molecular structure, so it can form a variety ofhydrogen bond between molecular chain.Polyurethane acrylate has good flexibility andtensile strength. Polyurethane acrylate UV-curable coating has a good adhesion to basematerial and has good low temperature resistance, abrasion resistance and so on. Therefore,polyurethane acrylate is widely used in UV curing coatings system.In this article, the polyurethane acrylate was synthesized with toluene diisocyanate(TDI),Polyoxypropylene triol, hydroethyl methacrylate. The-NCO content in polyurethane acrylatewas measured, the molecular structure and molecular weight were characteried by infraredspectrum and gel chromatography. The influence factors (processthe ratio of raw materials,reaction temperature, catalyst, reaction time, way of feeding raw material and moisturein theraw material) on the synthesis were studied.The result showed the best method of preparing polyurethane acrylate was that make theraw material moisture content less than0.05%, the best ratio of raw materials as follows: themole ratio of toluene diisocyanate and Polyoxypropylene triol, hydroethyl methacrylate is3.08:1:3. Polyoxypropylene triol was added to the TDI by the way of multiple adding.Dibutyltin dilaurate is used as catalyst, the optimum content is0.3%. The best content ofdiluent HDDA is20%. In the process of the reaction of polyurethane acrylate synthesis,thefirst step reaction temperature is65-70℃, reaction2hours or so.The second step reactiontemperature is under70℃for1hour, in the reaction (80±2)℃for2hours, reacts under85℃for1hour after get transparent viscous liquid polyurethane acrylate.With the synthesized oligomers, polyurethane acrylates UV-curable coating wasprepared and has excellent comprehensive properties. By studying the curing rate, hardness,adhesion and chemical solvent resistance, the result shows that: the content of polyurethane acrylate is87%, light initiator content is5%, active diluent monomer is4%, the polyurethaneacrylates UV-curable coating is the best.