Studies On Teh UV-Curable Polyurethane Acrylate Elastic Coatings

Ultraviolet (UV) cured coatings, possessing the advantages of green environmental protection, fast curing and excellent performance, have made rapid development and extensive application in various fields. Polyurethane acrylate (PUA) is one of the most excellent performance oligomers of UV-curable coatings, which combines the advantages of polyurethane and polyacrylate. Although there have a lot of research about UV-curable PUA coatings, there is still much room for the development of obtaining PUA elastic coating with the application of UV curing technology.Based on the requirements of coating performance and the relationship between structure and properties of PUA, the structure of PUA has been optimized in this thesis. The appropriate raw materials were selected and the synthetic conditions of PUA were also explored from several aspects of the reaction time, reaction temperature and synthetic route, etc. The optimized process condition of PUA was acquiered:The first step, long-chain diol, small molecule chain extender, and diisocyanate react and turn into the prepolymer with NCO group under the temperature of80℃, then add0.1%of the total quantity of di-n-butyltin dilaurate as the catalyst after2h; the second step, adjust the reaction temperature to70℃after the first step reaction of4h, add HEA with the amount that consistent with the theoretical excess moles of NCO and use4%of the whole quantity of the4-Hydroxyanisole as the inhibitor, we can get the PUA after the reaction of about2h. In this process conditions, the molecular weight of PUA is controllable when the setting molecular weight is below1×104, the synthetic process is stable and repeatable.A series of linear PUA with different components were prepared by different raw materials of isocyanate (TDI and IPDI) in this dissertation, the situation that the isocyanate index, hard segment and reactive diluent influence the mechanical properties was explored. And the PUA resin with best comprehensive mechanical properties was obtained. When the isocyanate index range is1.2to1.3, the molecular weight range of IPDI-PUA is about3200to5000. While the molecular weight range of TDI-PUA is about4700to5600when the isocyanate index range is1.2to1.25. The tensile strength and break elongation of the PUA cured film can achieve better comprehensive effect under these conditions, and it have excellent application results in PU leather.This article explored the curing properties of different UV-curable formulations with the PUA as main resin. Through researching the coating performance and applied effect in PU leather, we finally got the optimal feed ratio which made the PUA has excellent mechanical properties and the optimal UV-curable flexible coating formulation which made the PUA has excellent flexibility and other performance can meet the requirements. The optimal proportion was selected as follows:95%of PUA main resin,5%of TMPTA,3%of photoinitiator1173(percentage of the dominant resin and reactive diluents) and amount of solvent.