Synthesis and application to cotton of a polymeric black colorant prepared by grafting of reactive dyes to polyvinylamine

A novel polymeric black dye was synthesised by grafting yellow, orange, red, and blue reactive dyes onto polyvinylamine. Such a polymeric black dye takes the onus away from dyers to worry about the compatibility of individual dyes. The polymeric black dye was characterised by Fourier transform infrared, ultraviolet‐visible, and nuclear magnetic resonance spectroscopy. The absorption of the polymeric black dye in aqueous solution was nearly constant across the wavelength range 400–700 nm. Compared with a black mixture of reactive dyes with low fixation on cotton, which was prepared by mixing yellow, orange, red, and blue reactive dyes, the polymeric black dye reached 99% fixation on cotton through the use of a crosslinking agent. The colorimetric properties of cotton dyed with the polymeric black dye and with the black mixture of reactive dyes showed that better blackness can be obtained by using the polymeric black dye. Analysis of the thermal stability and penetration ability of the polymeric black dye showed that the polymeric dye has high stability in the application and a uniform distributution in the cotton fabric.