Synthesis and characterization of cationic carbon black pigment with quaternary ammonium groups and its dyeing properties for wool fabrics

Abstract

In this paper, the cationic carbon black pigment with quaternary ammonium groups was fabricated via the quaternization reaction of N,N-dimethyldodecylamine and epichlorohydrin-modified CB@SiO2 core-shell structure composites. The CB@SiO2 composites were prepared by stöber method using tetraethyl orthosilicate as precursor and carbon black (CB) nanoparticles as core. Scanning and transmission electron microscopic techniques (SEM & TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction method (XRD), thermogravimetric analysis (TGA), zeta potential and particle size distribution were employed to characterize the structure and properties of the cationic CB pigment as well as the intermediates. When the molar ratio of TEOS to epichlorohydrin to N,N-dimethyldodecylamine was 1:2.5:2.5, the zeta potential of the cationic CB pigment in aqueous dispersion reached the maximum +48 mv. The average diameter of the cationic CB pigment was ca. 45 nm with ca. 9 nm thickness of shell. Wool fabrics were dyed with the optimum cationic CB pigment through exhaust dyeing process. The L*a*b* values and the color appearance of dyed wool fabrics showed that the cationic CB-dyed wool fabrics had darker black and better fastness properties than the pristine CB-dyed wool fabrics.