| The epoxy-modified acryliate composite emulsion combines the advantages of epoxy resin with that of acrylic resin. Using water instead of organic solvent as dispersed medium, it reduces the environment pollution. Due to these advantages mentioned above, it presents a broad prospect of application in the field of film materials, adhesive, structural material. In this work, the composite emulsion prepared by water dispersion method was compared with that prepared by emulsion polymerization.The epoxy acryliate aqueous dispersion was synthesized by water dispersion method: First acrylic acid monomer were grafted onto aliphatic backbone carbons of the epoxy resin by the free-radical graft copolymerization in the present of initiator BPO, then neutralized with neutralization reagent, finally obtained the aqueous dispersion with addition of water. The effects of epoxy resin, acrylic monomer, solvent, initiator and neutralization reagent on the properties of aqueous dispersion were investigated. The results show that the comprehensive performance of epoxy acrylate aqueous dispersion was prefect when the reaction temperature is 110℃, the epoxy resin is EP828, acrylic acid made up14.5% of the total mass,2,2,4-Trimethyl-1,3-pentanediol monoisobutyrate is used as mixed solvent, the initiator made up 5% of the total monomer mass, and triethanolamine as neutralization reagent of neutralization degree 80%. The reaction mechanism of epoxy-acrylate grafting copolymer was studied by testing the content of carboxyl group and analyzing infra-red spectrum (IR). The sample was characterized by laser particle size analyzer. It indicated that its average diameter is about 180nm.The epoxy acryliate emulsion was synthesized by emulsion polymerization using acrylate monomer and epoxy resin modified by phosphoric acid. The dosage of phosphoric acid and the choice of solvent during the process of esterification, the ratio of emulsifier, the usage of initiator and epoxy resin, the ratio of soft and hard monomer and the reaction temperature during the process of polymerization were discussed. The conditions of preparing composite emulsion were also ascertained:the amount of phosphoric acid is 6%,2,2,4-Trimethyl-1,3-pentanediol monoisobutyrate and n-butanol are used as solvents, the ratio of emulsifier (Ms-1:OP-10) is 2:1, the amount of initiator is 0.6%, the amount of resin is 10%, the ratio of soft and hard monomer is 1:2, polymerization temperature is 85℃. Esterification mechanism was studied via IR spectrum. The reaction mechanism of epoxy resin and acryliate was studied by IR spectrum and transmission electron microscopy(TEM).Water resistance and crosslinking degree of film which cured at different curing temperatures was researched. The result shows that the curing reaction can complete better when the curing temperature is 140℃; The effections of curing time on crosslinking degree at curing temperature 140℃was also studied. The result shows that the curing time is 2.5h. Comparing the acryliate emulsion, epoxy acrylate aqueous dispersion and epoxy acrylate composite emulsion, the results show that:epoxy acrylate composite emulsion has excellent stability, storage time up to 12 months, film water-absorption is low, acid/alkali resistance, salt resistance are better. |
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