Carbon Black Surface Chemical Modification

Carbon black (CB) is one of the important pigments in coating or writing ink and is required to show good dispersing stability in water. Because of its special microstructure, particle configuration and surface behavior, carbon black is easy to conglomeration and hard to dispersion while using.The introduction of hydroxymethyl groups on carbon black surface was based on deeply analysis and discussing the way to modify carbon black inside and outside the country. Hydroxymethyl groups can be react with the active hydrogen in p-phenol sulfonic acid (p-PS) and the oligomer of p-PS and formaldehyde ( SPF). Then the modification of surface properties was investigated by introducing hydrophilic group onto carbon black.The effects of the reaction time and the solvent on the grafting yield were investigated. The grafted carbon black was characterized by FTIR spectrum,TG,TEM and dispersing stability test. Carbon black in water suspension without treatment was sedimentate within 5 minute. Dispersing stability of modified carbon black in water suspension was well improved. After 15 days' sedimentation, the transmittance at 720nm of p-PS modified carbon black in water suspension was changed from 1.5% to 11.4% and SPF modified carbon black, which grafting yield was 20%, was changed from 48.2% to 72.2%.In addition, liquid oxidation of carbon black was also discussed. Nitric acid and H2O2 was used as oxidant. The effect of oxidation time and temperature on the reaction was investigated. Fe/CB composite particles were obtained by pyrolysis of Fe3 cation exchanged carbon black, which was oxidized. XRD, EDS and TEM investigation disclosed that amorphous ferric oxide was uniformly dispersed on the surface of carbon black.