Study On The Influential Factors And Improvement Measures Of Rain Prints Of The Exterior Latex Paint

The outer wall coating has been widely put into application for its low resource consumption, easy construction and update, abundant colors and varieties without any hidden dangers. With its water-based environmental features, latex paint has already become the leading product in the outer wall coatings. Nevertheless, a problem which seriously affects the decorative effect of latex paint in the engineering application is rain print. Currently, without absolute solution to this drawback, the poor ability of latex paint to resist the rain print severely hinders its application.This paper conducts a comprehensive research on the influences to the rain print of the pigment percent volume concentration PVC, latex, wetting agent, dispersant, color paste and other auxiliaries. By testing the water white resistance of early latex and water sensitivity of wetting dispersant, this thesis attempts to explore the obvious effects of the two different performances to the emergence of rain print. What is more, the paper proves that the wetting dispersant’s migration after its film formation to the surface of lacquer film contributes significantly to the formation of the rain print by designing experiments to analyze the depositions on the surface of latex paint film.The experimental result shows that the most obvious rain print appear when the amount of admixture is around 30%, and less obvious as the admixture amount become bigger. The worse water white resistance of early latex, the easier it is to produce rain marks. No-soap latex has the best resistance to the rain print, then the silicone acrylic emulsion, while the pure acrylic emulsion is the worst in the experimental-use latexes. The better water sensitivity of the wetting agent and the dispersing agent, the easier it is to produce rain print. The dispersing agent with hydrophobic modification has the best resistance to the rain print, then the ammonium salt dispersant, at last the sodium salt dispersant. As for the water-based universal colorants, the ferric oxide inorganic ones exert lesser impacts on the rain marks; on the contrary, all the organic ones have much bigger effects and the carbon black colorants will have the worst influence on the production of the rain print. Thus, in order to avoid the problem of rain marks, the content of the carbon black should be controlled within 4%, and the other organic colorants, less than 8%.By coating the finishing varnish with excellent water-repellent properties on the surface of latex paint, the problem of rain print can be greatly reduced. Washing with fresh water is an effective solution to the reduction of the rain print.