Study On Preparation And Properties Of SF/Hollow Glass Beads/Titanium Dioxide Composite Thermal Insulation Coating

In this paper, the fluorocarbon emulsion is prepared with pre-emusification semi-continous seed emulsion polymerization technology,SF are dissolved by the three initiatives sol of Calcium chloride ,deionized water and ethanol (mole ratio is 1:8:2). The aggregates,mineral wool and fillers were selected. The composite thermal insulation coating which based on mechanism of reflection and obstructing was prepared with fluorocarbon emulsion and SF(silk fibroin) as basic material, And the effects of each factor on heat reflectivity and thermal conductivity were analyzed with orthogonal method and single-factor method. The optimal formula was determined and the product performances were tested.The influencing factors of the polymerization conditions ,emulsifier formula and amount ,the dosage of initiator on the emulsion properties are studied. The optimal formula of fluorocarbon emulsion as follows: Methyl methacrylate : butyl acrylate : butyl acrylate hexafluoropropylene (mass ratio) = 7:7:6, the dosage of initiator is 0.03 % of the monomer, emulsifier is 4 %, buffer is 2 % and protective colloid is 4 %. The results of FT-IR show that the fluorocarbon emulsion is synthesized. The SEM graphs of emulsion film reveal that surface of emulsion membrane is smooth and compact, its contact angle to water is close to 90°, to n-octanol is more than 80°. The rest basic properties of the coatings are qualified.The composite thermal insulation coating was prepared with fluorocarbon emulsion and SF(silk fibroin)as basic material,while expanded perlite and sepiolite as the aggregates, alumino silicate fibers as the mineral wool, titanium dioxide and hollow glass beads as the fillers.Through perpendicular experiments, the effect weight of these factors for heat reflectivity were obtained:aluminosilicate fibers > hollow glass beads > titanium dioxide > expanded perlite > sepiolite,while the influence on thermal conductivity were:aluminosilicate fibers>hollow glass beads >expanded perlite>sepiolite>titanium dioxide.Furthermore,formula of the insulation coating was optimized by single factor experiment:fluorocarbon emulsion,50g, SF,20g, deionized water,15g, various additives,6g, aluminosilicate fibers,11g, expanded perlite,3g, hollow glass beads,15g,titanium dioxide,15g,sericite powder,9g.Because of SF sol are added to coating, properties of thermal insulation coating are reinforced in the experiment.The average shear bond strength of the insulation coating was 665KPa,it could be raised to1031KPa after high temperature treatment,viscosity 2.133~4.066Pa·s,pencil hardness 9H,adhesion grade 1~2, its endurance to acid,alkaline and salt was strong.The reflectance of the coating at the visible band >78%,and the thermal conductivities were in the range of 0.054 to 0.074W/(m·K), SEM showed that the surface of the coating was compact,and the interior was loose,so the properties of heat insulation and water proofness were excellent.The composite thermal insulation coating could be widely applied in various fields.