| Waterborne polyurethane(WPU)is a green and environment-friendly product known for its excellent cold resistance,wear resistance and viscoelasticity.It is widely used in many fields such as ink,coatings,adhesives and biology.Polyurethane itself is extremely difficult to disperse in water,the introduction of hydrophilic groups is an effective way to make it water-based,but at the same time,the water resistance and solvent resistance of WPU are seriously affected.In order to make up for the shortcomings of WPU,in this study,fluorinated acrylate and epoxy resin were introduced to modify it.A series of fluorinated acrylate modified waterborne polyurethane(WPUFA)emulsions were synthesized using polytetramethylene glycol(PTMG)and isophorone diisocyanate(IPDI)as the main monomers,pentaerythritol triacrylate(PETA)as the grafting agent,and 1H,1H,5H-octafluoropentyl methacrylate(FA)as the modifying agent.The influence of WPUFA performance affected by PETA content and FA content was investigated.The results showed that with the increasing content of PETA,the tensile strength of the film increased to 15.96 MPa,and the water absorption decreased to 16.94 %.The particle size of the emulsion was the smallest when the PETA content was 40% of the molar mass of the residual-NCO in the polyurethane prepolymer.The addition of FA not only increased the particle size of the emulsion,decreased the viscosity of the emulsion,but also improved the tensile strength,water resistance,glass transition temperature and crystallinity of the film.In addition,hydroxyethyl methacrylate(HEMA),trimethylolpropane diallylether(TMPDE)and pentaerythritol triacrylate(PETA)were introduced into WPUFA as grafting agents,respectively.The effects of grafting agent types on the performance of WPUFA were compared.It was found that the emulsion synthesized by PETA possessed the largest particle size,which was 79.6 nm,the highest tensile strength of the film,which was 11.32 MPa,and the lowest water absorption,which was22.40%.The particle size of the emulsion synthesized by HEMA was the smallest,which was 72.0 nm,and the tensile strength of the film was the smallest,which was 7.41 MPa.The film synthesized by TMPDE had the highest water absorption of 28.87%.However,the use of FA modified WPU alone can’t meet the needs of multiple fields.In this paper,in order to further improve the performance of WPU and broaden its application fields on the basis of binary modification,bisphenol A epoxy resin(EP)was introduced to carry out ternary modification to synthesize a series of fluorinated acrylate/epoxy resin composite modified waterborne polyurethane(EWPUFA)emulsion.The effects of EP type and E-44 content on the properties of EWPUFA emulsion and film were studied.It was found that when different kinds of EP were added,the larger the epoxy value of EP was,the smaller the particle size of the corresponding emulsion,the larger the water absorption and contact angle of the film,and the smaller the tensile strength.When E-44 with appropriate epoxy value was added,with the increase of E-44 content,the particle size of the emulsion increased to 201.4 nm,the tensile strength and thermal stability of the film were improved,the contact angle decreased to 82.4°,the water absorption decreased to 6.40%,and the crystallinity also decreased.Based on the FA and E-44 composite modified WPU,the EWPUFA emulsion of three different internal structures of crosslinked EWPUFA-C,self-crosslinked EWPUFA-S and non-crosslinked EWPUFA-N were synthesized.The results show that the EWPUFA-C emulsion had the smallest particle size,of 104.9 nm.The mechanical properties and thermal stability of EWPUFA-C and EWPUFA-S films were higher than that of EWPUFA-N films,while the water absorption and contact angle were lower than that of EWPUFA-N films. |
PDF Full Text Request