Preparation And Properties Of Waterborne Dispersions Of Ultrafine Organic Pigments

Waterborne ulrafine pigments with excellent properties have been widely used in ink jet printing inks, dyeing and printing of fibers and so on. Waterborne ulrafine pigment dispersion (UPD) was prepared by sedimentation. The performances of UPD were also investigated in this paper.The effect of process conditions on pigment particle size and its distribution were investigated. The results show that the particle size increased first, and then decreased with the increase of milling rotate speed. The particle size and its distribution dereased with the increase of the milling time, but when the milling time was above 60min, the particle size and its distribution remained unchanged with further increasing the milling time. Dropping rate of adsorption accelerants would greatly affect the particle size and its distribution. The slower the dropping rate of adsorption accelerants was, the smaller particle size and narrower particle size distribution was obtained.The effect of modification reagents'structures, ionization degree and additives on particle size,ξ-potentials, centrifugal stability and the adaptability to the temperatures of UPD were discussed. The results show that the particle size decreased first and then increased, the centrifugal stability increased first and then decreased andξ-potentials increased with an increase in the molar ratio of–COOH of modification reagents (FM) which encapsulated onto the pigment surface. The particle size would be greatly changed at different temperature when FM was too high or too low. When the intrinsic viscosity of modification reagents ([η]) was at the range of 23.50mL/g～164.20mL/g, the particle size decreased first and then increased with increasing [η], centrifugal stability andξ-potentials increased with increasing [η]. The particle size was changed greatly at different temperature when [η] was too high or too low. The particle size first decreased and then increased with increase the amount of modification reagents, when the the ratio of modification reagents on pigments was 10%, the particle size reached to its minimum and r60 reached to 100%. The particle size was greatly changed at different temperatures with little amount of modification reagents.