Research on Thioalcohol-click Modification of PVAc-based Core/shell Emulsion and Its Rapid Film Forming Performance
Focusing on the issue of slow film formation and low coating efficiency of conventional waterborne coatings,thioalcohol-modified polyvinyl acetate(PVAc)-based emulsion was fabricated by grafting multifunctional thiols(TMPMP)on the surface of PVAc-based core-shell latex through the thiol-ene click reaction.After that,the fast UV-curable composite emulsion was prepared in one-pot method through adding pre-emulsified active monomer containing double bonds at the late stage of latex formation.The stability,photocuring characteristic,mechanical property and paint film performance of the composite emulsion were systematically investigated.The results showed that the particle size of PVAc-based core-shell latex was about 200 nm.Thioalcohol groups modified on the surface of the latex particles were able to react with reactive monomers in a thiol-ene click reaction under UV light irradiation for fast film forming and curing.The composite emulsion exhibited excellent stability which could be stored for more than 60 days.Appling to wood coatings,UV curing could be achieved in as fast as 9 s.Meanwhile,the performance of paint film could be improved by adjusting the ratio of thioalcohol to active monomer.When the dosage of active monomer(TMPTA)was 400％,the mechanical performance of light-cured latex film was obtained with the tensile strength of 6.17 MPa and elongation at break of 1.79％.In addition,the hardness,gloss and roughness of the wood coating film could be reached to 4H,10.8°and 2.34 pm,respectively.The thioalcohol-modified PVAc-based photocurable composite emulsion could achieve rapid film curing,which in turn significantly improved the coating efficiency and demonstrated a broad application prospect in the waterborne wood coatings.
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