| Emulsion paint with low pollution, low cost, easy coating, easy to clean, fine permeability, environmental friendly, and many other advantages, was given more and more attention. But some performances of emulsion paint can not exceed the organic solvent coating, such as antifreezing, antiseptics and anti-mildew, water resistance constructability and high temperature and humidity resistance, and so on. These facts limit the application of emulsion paint in many areas.As an effort to solve these problems, this paper focused on silicon-acrylate emulsion as the main film-forming material, by adding titanium pigment and kaolin clay as pigments and fillers,2-butoxy ethanol as film formation and tri-isobutyl phosphate as defoamer Through choosing three different environmental friendly water-soluble polymer (konjac powder, CMC and PVA) as thickening agents, the structure and rheological properties of silicon-acrylate emulsion systems were researched. After the systems with good structure and performance were prepared, the basic properties and static rheological behaviors were tested and researched.The results indicated that the basic performances of the silicon-acrylate emulsion system such as surface drying, complete curing time, water resistance, alkaline resistance, impact resistance, flexibility, adhesion, solid content, storage stability and construction were improved. Through the comparison and analysis, we found some performances had a huge difference, including water resistance, alkaline resistance and solid content. Finally we got the best mass ratio of acrylic acid emulsion paint. The static rheological tests demonstrated that silicon-acrylate emulsion systems were typical non-newton pseudoplastic fluids. At different temperatures (25,50and75℃), the apparent viscosity was decreasing to a constant value with the increasing of shear rate which meaned the system of non-newtonian fluid was shifting to Newton. And the relationship between the shear rate and the apparent viscosity could be fitted to the Cross equation; In addition, shear stress also changed along with the increasing of shear rate, which the relations between the shear rate and shear stress could be fitted to the Herschel-Bulkley equation. Because of different structures of three Water-soluble Polymers, the temperature dependence of apparent viscosity of three different systems were different. The silicon-acrylate emulsion system containing PVA was less dependence on temperature satisfying the experimental purpose. |
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