| Organosilicon/SiO2hybrid material was a new material combined the silica with organosilicon by the covalent bond. It was a combination of both the excellent characteristics, and had better compatibility and stability because it was a system of whole silicon. UV curable was a curing method which had the advantages of high efficiency, environmental friendly, energy saving and suitable for heat sensitive substrates. It could combine the advantages of both if applying UV curable to the preparation of organosilicon/SiO2hybrid coatings.In this paper, a UV curable organosilicon/SiO2hybrid sol was synthesized by the method of sol-gel which tetraethyl orthosilicate (TEOS) as the precursor of inorganic component, methyltriethoxysilane (MTES), diphenyldimethoxysilane (DDS) and γ-methacryloxypropyltrimethoxysilane (KH-570) as the precursors of organic component. Then the hybrid sol was as oligomer to obtain transparent organosilicon/SiO2hybrid coating after UV curing.The influencing factors of viscosity and stability of organosilicon/SiO2hybrid sol, such as reaction temperature, polymerization time, ethanol addition amounts, hydrochloride addition amounts and water addition amounts, were researched firstly. Then the preparation technology was determined by the evaluations of viscosity and stability, which was reaction at room temperature for a period of time in the beginning and then synthetization at70℃, polymerization for6h, addition amounts of ethanol, hydrochloride and water in the molar ratios of EtOH:HCl:H2O:Si as2:0.002:2.5:1. It was also found that adding the hydrochloride and water after mixing in drops was better than adding them one trial to obtain the target product. FT-IR of silicon sol and organosilicon/SiO2hybrid sol showed that the precursors all involved in the hydrolysis-condensation reaction, and obtained the UV curable organosilicon/SiO2hybrid sol.The FT-IR of organosilicon/SiO2hybrid coatings before and after UV curing showed that the double bond in the hybrid system was conversion under UV irradiation. A best curing time,30seconds, was determined by the reference of coating status, heat-resistant and corrosion resistance. The optimum molar ratios of TEOS:MTES:DDS:KH-570as6:9:4:5were get through the orthogonal experiment, which hardness, impact resistance, flexibility, adhesion and heat resistance were as the evaluation index. Microstructure observation of surface showed that the hybrid coatings were smooth and density. The results of performance tests indicated that organosilicon/SiO2hybrid coatings had excellent mechanical properties, heat resistance and great resistance properties of water, salt-water, salt spray and hygrothermal. Finally, the corrosion resistance mechanism of organosilicon/SiO2hybrid coatings was studied by the electrochemical impedance spectroscopy. A difference with the general organic coating was discovered, which the corrosion resistance property of organosilicon/SiO2hybrid coating increased in place of reducing in the later period of immersing in3.5wt%NaCl solution.Study on performances of different SiO2contents of organosilicon/SiO2hybrid coatings indicated that the appropriate addition amounts of SiO2could effectively improve the heat resistance, corrosion resistance and the hardness without loss of flexibility of the organosilicon. However, if SiO2was added too much, the effect reduced. The performance study of UV curable organosilicon/SiO2hybrid coatings derived from different addition amounts of KH-570showed that the increasing of KH-570could improve the corrosion resistance while reduce the heat resistance, and little influence to the mechanical properties. |
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