Study Of Nano-SiO₂ Modified Pure Acrylic Emulsion

In this paper, a kind of environmental friendly nano- SiO₂ composite coating was studied, which can be used for high performance exterior wall coating. The paper mainly includes the contents as follows.(1) Two methods were adopted to modify nano-particles. One is coupling reagent: KH-570, titanate and stearic acid were utilized; Another is graft on surface, in which methyl methacrylate was introduced to clad nano-SiO₂. The infrared spectrograms show that there are tow peaks around 1700 cm"1 and 2800³000cm^-1, which indicates that the organic group successfully connected to nano-SiO₂. The results show that the facial properties of the nano-SiO₂ are improved such as the dispersancy in organic macromolecule, the wettability, the binding power and cetera.(2) The pure acrylic emulsion for coating was synthsized by semi-continue emulsion polymerization, with the monomer of methylmethaclylate(MMA), butyl acrylate(BA) and acrylic acid(AA). The influencing factors on the product properties were investigated as the quantity of initiator and emulsifier, pH value. The good product of pure acrylic emulsion can be got when the propertion of the sample is 3% emulsifier, 0.35% initiator, n(BA)/n(MMA)/n(MA)=45/53/2, n(SDS)/n(NP-10)=1, 8-9 pH value, 2.5% KH570.Nano-SiO₂ hybrid pure acrylic emulsion was synthesized by in-situ polymerization, and nano-SiO₂ was well dispersed in emulsion by TEM. The viscosity was changed as the modifier varied, agglomerate ratio, solid-content, water absorbance were reduced with the accession of nano-SiO₂, and resistance to abrasion was improved.( 3 ) The coating's formulation is determined in terms of...