Preparation And Performance Of Multi-color Heat-reflective Insulation Coatings

Heat-reflective insulation coating is a functional coating materials, which has a highreflectivity for the energy of solar radiation, and can block heat conduction, and on the longwavelength part of the energy absorbed can launch out to the outside world withoutconsumption of energy to lower coating surface temperature （passive cooling）. Heat-reflectiveinsulation coating can be used for buildings or tanks, etc. surface, serve to reduce surfacetemperature, and thus play to save the energy consumption of refrigeration equipment, and candelay the aging of the substrate, and because the coating base material to be used is moreenvironmentally friendly water-based emulsion, is an energy-saving materials. Hollow glassbeads is the key technologies to prepare the efficient reflective insulation coating, and it has ahigh reflectivity and radiation at the same time to the sunlight,because of its mixture of thin air,hollow structure.It can form in the coating with cavity layer of low thermal conductivity, andplay a good insulation as a barrier for heat conduction, but it also exposed its shortcomings,forexample,poor compatibility with aqueous solvents, poor water resistance, easy-to-floating in theprocess of storage of the coating material, and not easy to use dispersion. The modification ofthe hollow glass beads surface is becoming focus research of the subject.In this paper, the double layer coating was adopted to prepare the dye type hollow glassbeads, the first layer coated with TiO₂film, two layer coated with Fe₂O₃film. To analyze theeffects of salt solution quality, system pH, temperature, reaction time, stirring speed on thecoating effect and reflectivity,a combination of methods of the optical microscope andspectrophotometer was used, and to observe the state of coating layer and analyze the product,the SEM, XRD and other tests were used. The results showed that, the appropriate conditions ofTiO₂first layer coated hollow glass beads were: TiCl₄solution130mL, reaction temperature70℃, pH value of the system3, a feeding time control in6h, stirring speed300r/min; Fe₂O₃thesecond layer was coated in the appropriate conditions: reaction temperature80℃, pH value ofthe system4, coloring time60min, according to5g TiO₂first layer coated hollow glass beads,the15%FeCl₃solution30mL needed, and the calcination treatment for the sample at650℃also needed, namely after all that the double coated specimens were obseved. The experimentalresults showed that by means of the method of solution separated with that of the first coatingto coat Fe₂O₃, the sample color, reflectivity, dispersion stability, ageing resistance and waterresistance were improved.According to the heat reflective thermal insulation coatings function principle, the mainfactors of the effect of heat reflection coating thermal insulation properties were studied in thispaper,including the film-forming material, pigment and filler content types, pigment and filler particle size, and the experimental formula design was optimized.the results showed that: thebest thermal insulation was observed with the thermal insulation coating formulations insilicone acrylic emulsion with the content of30%, the rutile type titanium dioxide10%, GCC20%, talcum powder5%and the double coated hollow glass beads10%¹5%, and Under thisformula,a Insulation temperature difference of14.9degrees was reached, and the ideal ageingresistance and water resistance were achieved.In addition, as the color rich polychromatic coating had better decorative effect, at thesame time of the golden brown double coated hollow glass beads added, introducing the newCICP pigments and fillers were introduced,to obtain coating formulations with various dark andat the same time a highly reflective on the solar radiation. The self-made heat reflectivecoatings were studied on discoloration resistance, and compared with commercial coatings. Theresults show that: the self-made coatings had a higher reflectivity than the ordinary coatings.