Synthesis Of Hyperbranched Urethane Acrylate And Its Application In The UV Curable Coatings

In this paper,the hyperbranched unique molecular structure combined with UV curing technology to synthesize hyperbranched urethane acrylate,and optimize the preparation formulation of UV curable coatings with excellent property.Firstly,the hyperbranched urethane prepolymer(HPU)was synthesized from pentaerythritol and isophorone diisocyanate as the main raw materials.And the semiaddition product IPDI/PEG/HEA containing soft segment was introduced to modify hyperbranched polyurethane hydroxyl group and synthesize hyperbranched urethane acrylate(HPUA).The FTIR and NMR indicate that the molecular structure contained a urethane bond and an unsaturated double bond.And the synthesized product had a hyperbranched structure with the degree of branching was 0.869.The maximum thermal decomposition temperature was 307.9 °C.The thermal properties were stable,and Low resin viscosity was 136 mPa.s.Secondly,the above-mentioned synthetic HPUA was used as the base resin of the UV curable coatings.By investigating the influence of the amount of different resins,the types and amounts of different reactive diluents,the types of different photoinitiators on the coating properties include curing speed,hardness,adhesion,water resistance,acid and alkali resistance,etc.The experimental results showed that when the amount of HPUA was 40%,the amount of reactive diluent in the compounding system was 20%,the radio was TPGDA:TMPTA =1.5:1,and the amount of the photoinitiator in the compound system was 3~5%,the radio was TPO:1173=1:1,the prepared UV-curable coating had a curing time <15 s,a hardness >4 H,a viscosity <150 mPa.s,and adhesion reached level 0.In addition,it also had good flexibility and excellent hydrolytic resistance.Finally,the UV-curable coating prepared by the HPUA and the self-made PUA,as a matrix resin were compared.The results showed that the performance of HPUA UV-curable coating was significantly improved,in which the curing time was reduced by 57.1%,the pencil hardness was increased by 2 times,the adhesion reached the maximum level 0,the viscosity was lowered,the acid and alkali resistance were excellent.The flexibility was increased by 50% and the water absorption rate was reduced by 50.8%.The maximum thermal decomposition temperature increased by 12.7%,showing excellent overall performance.