The Study On Synthesis,modification And Properties Of Multifunctional Waterborne Polyurethane

Waterborne polyurethane(WPU)has attracted more and more attention due to its excellent environmental protection characteristics.It has gradually replaced solvent-based polyurethane products and been widely used in our life.Water is used as the dispersing solvent in WPU,which makes WPU have the advantages of low viscosity,low toxicity,low pollution and low cost.But at the same time,it has obvious disadvantages,such as poor water and heat resistance,relatively general mechanical properties.For this reason,we often need to modify WPU.Multiple modification usually has better effect and can endow WPU with multi-function.In present work,Linear waterborne polyurethane/imide was synthesized from isophorone diisocyanate(IPDI),polytetrahydrofuran glycol(PTMG2000),2,2'-dihydroxymethyl propionic acid(DMPA),1,4-butanediol(BDO),pyromellitic anhydride(PMDA).Linear waterborne polyurethane/imide(FWPUI)was then synthesized via free radical copolymerization used hydroxyethyl acrylate(HEA)and hexafluorobutyl methacrylate(HFBMA).The experimental results showed that the addition of organic fluorine significantly reduced the water absorption swelling of WPU,while the introduction of imide structure significantly improved the thermal stability and tensile properties of WPU.The combination of the two modifications maked linear WPU have many functions such as water resistance,high temperature resistance,good mechanical properties and so on.Then the synthesis,modification and application in coating fieldof cross-linked WPU were further explored.Crosslinked fluorinated waterborne polyurethane coating(WPU-TFA)was synthesized by IPDI,PTMG2000,DMPA,BDO and self-made triamine monomer containing C-F chain and aromatic ring structure(TFA).WPU was tri-modified by crosslinking modification,fluorine modification and introduction of rigid chain.The results showed that with the addition of triamine monomers,the water absorption swelling of WPU decreased significantly,the contact angle of water surface increased significantly,the ultraviolet and heat resistance also improved significantly.In addition,the adhesion,pencilhardness and scratch resistance of WPU coatings also improved significantly.,which provided people confidence in replacing oily coatings.