Synthesis of polymeric dyes based on UV curable multifunctional waterborne polyurethane for textile coating

Three novel UV curable polymeric dyes (UVPDs) based on multifunctional waterborne polyurethanes have been successfully developed to overcome the drawbacks of thermo-curing. The functionality of the UVPDs is tailored by end-capping with 2-hydroxyethyl acrylate (HEA), pentaerythritol triacrylate (PETA) and dipentaerythritol pentaacrylate (DPEPA). The chemical structure, molecular weight and carbon-carbon double bond (CQC) content of the UVPDs were investigated. The thermal properties, curing behavior and color properties of the UVPDs are also discussed. It is found that the thermal stability of the UVPDs is improved upon increasing the functionality. The incorporation of chromophores into the polyurethane chain reduces the curing efficiency. The curing behavior observations demonstrate that the UVPDs can cure rapidly upon UV irradiation, especially the ones with higher functionality. A higher degree of cross-linking and better water resistance are obtained when UVPD films are cured with 5% photoinitiator. Furthermore, the UVPDs show outstanding UV light stability. The maximum absorption wavelength and curve trend of the cotton fabrics coated with the UVPDs remain unchanged while the color of the coated cotton fabrics slightly lightens when prolonging the UV curing time. The color fastness to rubbing and washing of the coated cotton fabrics with UVPD10 can be enhanced up to 4-5 grade after curing for 60 s.