Synthesis And Performance Of Ambient-curable Epoxy Modified Water-borne Alkyd Resin

Water-borne alkyd resin is wildly used in various fields because of its low cost, pollutionfree, excellent properties. However, as properties of water-borne alkyd resin can’t meet therequirements due to its low hardness, slow drying rate as well as its solvent resistance,properties of product could be improved using epoxy to modify water-borne alkyd resinaccording to excellent physical and mechanical, dielectric, chemical resistance and adhesiveproperties of epoxy. Therefore, the researches and developments of waterborne epoxy resinhas an extremely broad perspective in application. In this thesis, epoxy ester was prepared byusing unsaturated fatty acid to modify epoxy which then was considered as polybasic alcoholto react with other raw materials to prepare basic alkyd resin which later was grafted byhydropHilic monomer, and after its neutralization and dispersion, an air-drying water-borneepoxy modified alkyd resin was prepared. the effects of each factors on the productsperformance were discussed, the final experiment formulation and technological conditionwere obtained.Results showed that in the process of preparing water-borne alkyd resin, the sort of rawmaterials, dosage and technological condition played a decisive role in performance ofproducts. The appropriate reaction condition could be: using linolenic acid, pHthalicanhydride, trimethylol propane, trimelitic anhydride as raw materials; using solventmethod/melting method as synthetic method; reacting temperature started from180℃andheld at this temperature for1hour, then rose reacting temperature to230℃at the rate of30℃/h and held at this temperature for1hour. Therefore, a stable water-borne akyd resincould be prepared; controlled the oil length at45~55%, the excess glycol at7%; controlledthe acid value at7and50~70separately before and after adding trimelitic anhydride.Alternative condition of Latent solvent and neutralizing agent: selecting normal butanoland ethylene glycol monobutyl ether (1:1) as latent solvent, triethylamine as neutralizingagent.When content of epoxy resin was12%~16%and the reaction temperature ofsynthesizing epoxy ester was190℃, the hardness, adhesion, stability, water-resistence,solvent-resistence of modified resin would be the best. Several testing methods such as FTIR, DSC were adopted to characterize Polymer.Malvern particle size analyzer was used to test the particle size and its distribution. FTIRspectra showed that E-20was estered and ring-opened by linolenic acid, and further reactedwith other raw materials; two glass transition temperatures of the polymer which wasmodified by E-51could be clearly observed in DSC curve at-0.01℃and57.67℃, one glasstransition temperature of the polymer which was modified by E-20at-5.29℃could beclearly observed in DSC curve; Malvern particle size analyzer showed its average particle sizewas24.2nm, with PDI0.142.