Preparation And Study Of Solventbasedthick-film Organosilicone Coating

Most of utilizations in the sun-shading field of buildings’ door and window are stillstagnant on scroll blinds and curtains, so artificial lighting and air conditioning are widelyused which results in huge energy consumption. In order to improve the situation, K STERinvented a toothed blind. The thickness of coating used on the surface of shutter is required toreach500μm because of the domestic technology difficulty of tip surface processing. Sothick-film coatings are required to prepare. Thick-film coatings with high solid areenvironmental friendly coatings because the solvent content of which is low. Thus, the studyof thick-film coatings has important significance.In this work, the methyl phenyl silicone resin was synthesized by hydrolysiscondensation method using MTMS and DDS as raw materials. The thick-film organosiliconecoating was prepared by using as-synthesized as binder. The effects of raw material γ(R/Si),synthetic process, solvent type, pH and solid content on viscosity, storage stability, chemicalresistance, water repellent, heat stability and basic physics performance of high solid contentsilicone resin solution were investigated. The results show the best preparation parameter ofhigh solid content silicone resin solution is followed, raw material γ(R/Si)=1.3, diethyleneglycolmonobutylether or DBE as solvent, and the solid content is chosen to be80%. Throughthe analysis of TG-DTG, mass loss of silicone resin prepared under neutral and alkalineconditions at400℃were only4.3%and6.8%, respectively, and their mass loss at500℃wereonly7.4%and10.2%, respectively which shows that as-synthesized silicone resin hasexcellent heat stability, and the heat stability is better under neutral condition.High solid content silicone resin solution was prepared by using as-synthesized methylphenyl silicone resin as binder. The effects of the auxiliaries (leveling agents, defoamers,dispersant), pigment (titanium dioxide) and fills (mica power, talcum powder, spherical silicapowder, nano-SiO2,) on the performance of the thick-film organosilicone coating were studied,such as defoaming time, viscosity, gloss, heat stability, pencil hardness, thickness of tipsurface and Coating surface morpHology. Here, the white thick-film organosilicone coatingwas studied only.Through the comparison test, the best formula of the white thick-film organosiliconecoating was obtained. Namely, the contents of titanium dioxide, mica powder, spherical silicapowder are20%,10%,10%,15%of silicon resin mass, respectively, and the contents ofleveling agent S43, defoamer900, dispersant670and nano-SiO2are0.75%,0.1%,0.3%and3%of the total formula mass, respectively, defoaming time of thick-film coating prepared isless than8hours, thickness under a film reaches500μm, without sagging, coating surface issmooth after cured and its gloss reaches106.3GS. The best curing process of thick-film coating using DBE as solvent is that coating is cured at100℃for1h, and then120℃for20minutes, and160℃for30minutes at last. There are no shrinkage cavities, bubbles, pocks andcracklings on the surface of coating deposited on aluminium alloy which had been treated bychemical corrosion and cured under the best curing process after two hours’ stewing. The besttip surface suppression mechanism is suppressing the coating at150℃, with5minutes’ heatpreservation. The thickness of the coating with tip surface achieves the qualified standard, andthe coating can be cured well, the pencil hardness and gloss of coating suppressed achieves3H and19.9GS, respectively.