Development of water-based polymeric dye and its application as a colorant for waterborne polyurethane

摘要

In this project, an eco-friendly aqueous synthesis method of water-based polymeric dye (WPD) was developed and its potential as a colorant for waterborne polyurethane (WPU) was tested. The WPD was produced by reacting polyethylenimine with commercial reactive dye in the warm alkaline solution. The colored polyurethane membrane was then produced via solution blending of WPD and WPU, followed by air-drying. The results showed that WPD with a wide variety of colors can be easily synthesized by selecting different precursory reactive dyes and can be easily blended with WPU via moderate stirring. The colored PU membranes have good transparency and the logo under them can be clearly observed. Compared with the pure polyurethane membrane, the absorbance of colored polyurethane membrane at the wavelength of maximum absorption increases at least 20.2% even if the content of WPD within the colored polyurethane membrane is as low as 0.16%, implying that our WPD has excellent color strength. Finally, the colored polyurethane membranes have very high colorfastness to water and can be stored in deionized water for 2 weeks without dissolution of WPD. As a result, our developed WPD is a promising and cost-effective colorant for WPU.