Mechanisms of pigment dispersion

In the “dry” state, pigment particles are held together by attraction forces of various physical chemical natures including the van der Waals force and the “liquid bridge” force. These attraction forces must be overcome in order to disperse pigment particles into liquid media. Dispersion machinery is designed to generate energy required to overcome, to various extents, such attraction forces. On the other hand, the efficiency of dispersion operation is significantly dependent upon the effectiveness of the transfer of energy from the dispersion tools/dispersion charges to the oversized pigment particles, as a result of the presence of the adhesion and cohesion within the dispersion system. This paper explores the nature and the significance of various forces between pigment particles and of the adhesion and cohesion phenomena associated with pigment dispersion, from a practical point of view. Principles relevant to improving the efficiency of pigment dispersion via minimisation of the adhesion between pigment particles and via maximisation of the adhesion and cohesion within the dispersion system are also discussed.