| In order to reduce the building energy consumption resulting from the widespread use ofair conditioning and heating equipment and achieve the goal of building energy efficiency,building heat-insulation coating has become one of the most important building energy-savingmaterials. The heat-insulation coating layer on a building external wall is exposed to anatmospheric environment, which make it inevitably contaminated. This will substantiallyreduce the solar reflectance of the heat-insulation coating layer, so causing poor heatinsulation effect. Therefore, it is of great significance in theory and practice to design andprepare building heat-insulation coatings possessing excellent stain resistance.Based on the analyses of the heat-insulation mechanism and contamination of a buildingcoating, a novel waterborne building heat-insulation coating was designed and prepared bydesigning and synthesizing the latex as film former and choosing functional heat-insulationfillers and additives. Effects of the components and their contents in coating formulations onheat insulation property and stain resistance were systematically studied, thereby revealing thedesign and preparation principles of the waterborne heat-insulation coating with stainresistance. This research work contains three main parts.In the first part, the acrylate copolymer seed latex was first synthesized according to theconcept of “particle design”, and then the self-crosslinking fluorinated acrylate latices havinga core-shell structure were synthesized using fluoride monomer(BY-F300) and organosilianemonomer(VTES) as functional monomers for shell polymer via the seeded emulsionpolymerization method. The properties of latices and latex films were characterized bytransmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS), thermogravimetry analysis(TGA), laser particlesize analyzer and contact angle goniometer, respectively. The effects of emulsifying system,initiator, BY-F300 and VTES on the properties of latices and their films were investigated.The results indicate that BY-F300 and VTES can be successfully copolymerized on the latexparticle surface in the seeded emulsion polymerization and the prepared latex particlespossess the core-shell structure as designed. The additives system consisting of 2.0 wt % of ananionic emulsifier SDS, 1.0 wt % of a nonionic emulsifier Triton X-100 and 0.6 wt % of aninitiator potassium persulfate is suitable for the seeded emulsion polymerization. Theself-crosslinking fluorinated acrylate latex prepared using this additives system and thereactant system containing 19.72 wt % of BY-F300 and 4.05 wt % of VETS can form thelatex film possessing excellent thermal stability and hydrophobicity, whose Tg and initialthermal decomposition temperature Td,5% are 28.3 °C and 376.4 °C, and the contact angle of awater droplet on the latex film is 111.2°.In the second part, titanium dioxide rutile(Ti O2), hollow glass microspheres(HGM),silica aerogel(SA) and far-infrared ceramic powder(FICP) that exhibit high reflectivity, lowthermal conductivity and high radiation efficiency were chosen as functional heat-insulationfillers/pigments, and then a series of heat-insulation coatings with different compositions wereprepared using the optimized self-crosslinking fluorinated acrylate latex as a film former. Theheat insulation property of the as-prepared coatings was measured by referring to theindustrial standard concerned. The effects of pigment volume concentration(PVC) and eachfiller or pigment content on the heat insulation property of coatings were investigated. Besides,an orthogonal method had been adopted to further optimize the combinational content level ofHGM, SA, talcum and kaolin. The results indicate that the appropriate PVC is 50% for thedesigned coating system; the coating layer contain 15 wt % of Ti O2 exhibits a relatively lowequilibrium temperature Te; and the coating to which 10 wt % of FICP with the size of 800 mesh is added can possess good heat insulation property. Among the designed coatingsystems, the coating bearing 6 wt % of HGM, 4 wt % of SA, 6 wt % of talcum and 2 wt % ofkaolin possesses the lowest Te, 43.1 ° C,which is much lower than those coatings onlycontaining HGM or SA.In the third part, based on the optimized formula of waterborne heat insulation coating,the heat-insulation coatings with stain resistance were prepared through the addition ofhydrophobe and film-forming additives that could reduce the surface energy of a coating layerand improve coating layer its compactness. Then, the effects of monomer composition oflatex, hydrophobe, film-forming additives and pigment volume concentration(PVC) on thestain resistance of coatings were systematically investigated, and the coating formula wasfurther optimized. The stain resistance and heat insulation properties of the coating preparedaccording to the optimized formula were comprehensively characterized. The results indicatethat compare with the coatings prepared using acrylate latices BLJ-961, BLJ-998 AD,BLJ-816 purchased from Bao Li Jia company as a film former, respectively, the coatingprepared using the self-crosslinking fluorinated acrylate latex L7 as a film former possessesbetter stain resistance, whose percentage reduction of reflection coefficient(XRC) andattenuation of thermal insulation temperature difference(ΔT) are 12.65% and 5.2 °C. Amongthe studied coatings prepared using different self-crosslinking fluorinated acrylate lattices asfilm formers, the coating prepared using the latex containing 4.05 wt % of VTES exhibitsbetter stain resistance. The coatings prepared by using the additives system consisting of 4.5wt % of hydrophobe SC011 and 3.0 wt % of film-forming additive SeikosolvTMEP-10 canpossess very low XRC, showing excellent stain resistance. Based on the effects of PVC on heatinsulation property and stain resistance, the optimum PVC for the coating system is 50%. Theoptimized waterborne heat inulation coating in this study can possess excellent stainresistance and heat insulation property, and its XRC and thermal insulation temperaturedifference are 10% and the being 18 °C, respectively. Both these two parameter values aresuperior to the corresponding values(20% and 10 °C) prescribed by the industrial standard(JG/T 235-2008). |
PDF Full Text Request