| The study of styrene-acrylic emulsion modified by epoxy resin both at home and abroad was reviewed. The emulsion was prepared by use of pre-emulsified addition and core-shell emulsion polymerization technology. The effect of surfactants, initiator, temperature, the ratio of soft monomer and hard monomer , epoxy resin, functional monomer on modified emulsion was investigated,and the best formulation was determined. The best formulation could be obtained when the contents of surfactants was 3.5 %, the ratio of surfactants was 1/1.5, the content of initiator was 0.6 %, the best temperature was 75℃78℃, the ratio of soft monomer to hard monomer was 1/1, the content of E-44 was 2%,the content of functional monomer(MAA,N-MA) was 2 %. The latent curing agent was added for promoting curing. The best cure condition was under 150℃for baking 40 min. The structure of modified emulsion was characterized by FTIR, the peaks at 915 cm-1 and 1251 cm-1 and 1726 cm-1 correspond respectively to the motion of epoxy, phenylate and carbonyl group. The thermal graviting analysis found that thermal decomposition temperature of modified emulsion was higher than unmodified emulsion. The contact angle was also from 34.77°to 63.05°.The distribution of emulsion particle was narrow and close to normal distribution. The ESI and polarization curve testing found that coat resistance had one order of magnitude increased, the corrosion potential had raised and the corrosion current had decreased. It proved that modified emulsion possessed better hydrophobicity, thermal stability, anticorrosive property compared to styrene-acrylic emulsion. The modified emulsion also had better waterproof ability, frost and thaw stability compared to unmodified emulsion.The coating was prepared with modified styrene-acrylic emulsion. This coating had outstanding waterproof ability, base proof ability, scrub ability and weather ability. The results showed: the best content of dispersant was 0.7 %, the content of film additive was 2.0 %, the content of leveling agent was 0.15 %, the content of bodying agent was 0.2 %, and the content of defoamer was 0.3 %. The best performance was obtained when PVC=54 %. The styrene-acrylic coating modified by epoxy resin was green and had good combination properties. |
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