| Organosiloxane and silica are rich in Si-O-Si inorganic structure,which may greatly improve the comprehensive performance of waterborne acrylic resin by introducing these material because of the high weather resistance and high strength of Si-O-Si structure.However,simply mixing these materials with waterborne acrylic resin tends to result in a loss of modification effect due to poor compatibility,poor stability,and uneven dispersion.In order to solve the above problems,in this thesis,high content of organosiloxane and colloidal silica were intimately mixed with waterborne acrylic resin at the nano-scale based on the sol-gel method and blending method.Thus,a stable organic-inorganic nano hybrid resin with high performance was obtained.Firstly,methyltrimethoxysilane（MTMS）,phenyltrimethoxysilane（PTMS）and dimethyldimethoxysilane（DMDMS）were used as precursors to form silicone oligomer containing Si-OH and Si-O-CH3 by hydrolysis and condensation reaction.The effects of relative amount of precursors,water consumption and preparation process were investigated.The chemical structure of silicone oligomer was characterized by FTIR and 1H-NMR.Next,an acrylic resin containing Si-OCH3,-COOH,and-OH was synthesized by solution radical polymerization,and then combined with the silicone oligomer to obtain a waterborne silicone-modified acrylic resin dispersion.DLS showed that the average particle size of the dispersion（obtained from the composition 8%AA,3%HEMA,30%silicone oligomer and other acrylic monomer）was 76 nm and the PDI was 0.193.TEM confirmed that the particle was sphere like with good dispersion and stability.The chemical structure of products at each reaction stage was analyzed using FTIR,demonstrating the occurrence of cross-linking reaction during film curing process.SEM showed that the hybrid resin film was compact and defect-free.And the organosilicon component underwent surface migration,which was detected by XPS.The silane coupling agent modified silica sol was introduced into a silicone-acrylic resin.It was found that a stable modified silica sol with a Zeta potential of-69.1 mV was obtained at a 10%silane coupling agent level.TEM showed that SiO2 was compact with the silicone-acrylic resin to form a stable hybrid particles.It was observed from AFM that the addition of silicone and SiO2 caused a slight increase in the roughness of the coating.Finally,the mechanical properties,water resistance,solvent wiping resistance and liquid medium resistance of the hybrid coating were studied.The results showed that the addition of silicone improved the water resistance and solvent wiping resistance of the coating.After an appropriate amount of SiO2 was added,the hardness of the coating can be greatly improved.The resistance to liquid media of coating was improved significantly because of the synergistic effect of organic silicon,SiO2,and acrylic resin. |
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