Abstract:

For developing water-based polyurethane with excellent mechnical properties and better water resistance, a prepolymer with vinyl end-capping was prepared using polyether polyols, toluene diisocynate, 2,2-dimethylolbutanoic acid and 2-hydroethyl methacrylate. These emulsions were used to copolymerize with methyl methacrylate, butyl acrylate and silicon monomers, including vinyltriisopropoxysilane (A173) and vinyl-ended polydimethylsiloxane (Vi-PDMS), to synthesize the silicon modified polyurethane acrylate emulsion. The chemical structure of the Si-PUA emulsion was characterized by Fourier Transform Infrared Spectrum. The water absorption and mechanical property of the Si-PUA film were investigated. The result showed that the increasing dose of A173 in the copolymerization could enhance the strength but reduce the elongation at break of the Si-PUA films. The presence of Vi-PDMS in the synthesis could give rise to better water resistance of the films but result in lower mechanical properties, especially for higher content of Vi-PDMS. When using 2.5% A173 and 3% Vi-PDMS in the synthesis of Si-PUA, the breaking strength of the resultant film was up to 1.65MPa, the elongation at break was 242%, and water absorption was as low as 8.32 %.

Key words: waterborne polyurethane, organic silicon, acrylic, crosslinking, water resistance