Preparation Of Waterborne And Room-temperature Curable Epoxy/Acrylate Resin

Waterborne epoxy/acry late resin which combines the advantages of both epoxy and polyacrylate is important for the development of modern coating systems.The building of stable dispersion and the introduction of room-temperature curable structures would be much preferred in coating applications.In this dissertation,epoxy esters containing unsaturated double bonds were prepared and then grafted with polyacrylate.The self-emulsification method was used to prepare stable waterborne dispersions.On the thorough optimum work on the preparation and components of various monomers and functional additives,the surface coating materials with excellent performance through the the oxidation crosslinking and oxidation/keto-hydrazine double crosslinking system were prepared.The dissertation includes the following contents:1.Epoxy esters containing unsaturated double bonds were prepared by ring-opening esterification under bulk-melting condition with tetrabutyl ammonium bromide as the catalyst.The change of acid values were monitored during the reaction process.A variety of reaction parameters were optimized.The reaction conditions were built as equivalent epoxy and carboxyl groups,1%of the catalyst and 3 hours of the reaction time.The product structure was characterized by Fourier Transform infrared spectroscopy(FTIR).2.The grafting reaction of unsaturated epoxy ester with polyacrylate was carried out by free radical reaction of epoxy ester and acrylate monomer.With the copolymerization of hydrophilic acrylic acid,the resin of epoxy-polyacrylate(EPA)could be dispersed in water after neutralization.The particle sizes and distributions of the dispersions were tested by dynamic light scattering(DLS).The morphology of the particles was characterized by transmission electron microscopy(TEM).The structures of the E-PA resin before and after the crosslinking reaction of the double bond oxidation were studied by FTIR.The characterization of differential scanning calorimetry(DSC),thermogravimetric analysis(TGA)and the test on the coating films were also performed.The effects of initiator dosage,reaction time,monomer dosage,dropping time of monomers,acrylic acid,degree of neutralization,different epoxy resin and the amount of drier on the product performances were studied.The preparation parameters were optimized to get self-crosslinking coatings at room temperature.The water resistance of coating was prolonged to more than 50 days,and the coating film with good corrosion resistance.3.In order to shorten the curing time and enhance the performance of the coating film,in the preparation of E-PA,diacetone acrylamide(DAAM)was copolymerized with acrylate to graft into the epoxy ester.After neutralization,proper amount of adipic acid dihydrazide(ADH)was introduced to form a one-pot two-component aqueous resin system.The effects of the addition amount of DAAM on the particle size and stability of the dispersion were studied.The water absorption,hardness,corrosion resistance and tensile properties of the resin were characterized.It was found that the double-crosslinking network was formed by the crosslinking of unsaturated double bond and DAAM-ADH.The properties of the film were improved and the curing time was shortened.4.The E-PA resins were modified by alkoxysilane A-151 and hydroxyethyl acrylate(HEA),respectively.The effects of the modifiers on the properties of the dispersions and films were studied.The results showed that with the introduction of different modifiers,the system performance was improved to different degrees.Through the sol-gel reaction of alkoxysilane groups,double-crosslinking network structure was also built with the double-bond oxidation crosslinking in the film.The curing temperature need to be at 60 ? or more.The glass transition temperature increased after film formation and the water absorption rate decreased.The increase on the content of hydrophilic monomer HEA would cause the decrease on the dispersion particle size.The hydrogen bond network of hydroxyl groups in the film also contributed to improvment of the mechanical properties.However,when HEA was excessive used,the dispersion stability decreased,and showed temperature-sensitive viscosity behavior.