Preparation Of Elastic Exterior Wall Latex Coating With Stain Resistance

Elastic latex coating is an advanced functional decorative material for exterior wall. It can prevent wall cracks and concrete carbonization and is more and more popular in the market. But elastic latex coating generally has poor stain resistance which restrains the application and popularization of its.In this dissertation, we focused on stain resistance of elastic latex coating. This research was based on surface interfacial principle of film, referring to stain resistance theory. The main objective was to improve stain resistance of elastic film. The formulas of single elastic latex coatings for exterior wall were optimized by selecting various film-forming substances, adjusting latex ratio, controlling PVC content and adding functional additives, etc. The finishing varnish product with high stain resistance for multi-layer coating system was prepared by selecting dilution proportion, adjusting viscosity and controlling pH value, etc.The results showed that high stain resistance of coating was mainly determined by surface properties of film. Low water absorptivity was beneficial to improving stain resistance of hydrophilic acrylic film & silicasol-acrylic compound film. The outdoor exposure tests showed that hydrophilic finishing varnish had better stain resistance than hydrophobic finishing varnish. Three kinds of single elastic latex coating product were prepared in this study and those were hydrophilic elastic acrylic coating, hydrophobic fluorine modified acrylic coating and elastic silicasol-acrylic compound coating. The comprehensive properties of each product were better than those of competitor's product and stain resistance value of film decreased by 2 to 12 outdoors. Stain resistance value of ordinary elastic acrylic coating that was covered with silicasol solution was only 13. Stain resistance of film increased by 66% than that of blank and also moved ahead of competitiors. This system of silicasol & ordinary elastic acrylic coating displayed the most excellent comprehensive properties, especially in stain resistance.