The dispersion of pigments is a key step in the configuration of coated paper coatings, and it is also a guarantee for the preparation of good coatings and the production of good coated papers. In order to better disperse the pigments, sodium hexametaphosphate needs to be used. The dispersion of pigments is also called the preparation of white materials, mainly by adding chemical dispersants and applying sufficient energy to destroy the flocculation of pigment particles and make them in a good colloidal dispersion state. In addition to the rational use of dispersants, pH, cationic electrolyte and dispersion time, strength, temperature, etc. also have a great influence on the dispersion of pigments.

A large number of dispersant anions are gathered on the surface of the pigment, and a large number of cations are gathered near the surface of these anions. From the perspective of the entire suspension system, the static balance of positive and negative charges has not changed. This is because the anions on the surface of the pigment adsorb excess cations (the reason for the excess cations is that the pigment preferentially adsorbs the anions of the dispersant), so that the cations are gradually concentrated around the surface of the pigment particles, thereby forming an electric double layer, and The cations are fixed in the adsorption layer. Due to the particle balance layer, the pigment particles repel each other and are in a stable state. Sodium hexametaphosphate can be connected to each other and polymerized into a long spiral chain, which can be adsorbed on the surface of the particles to enhance the hydrophilicity of the particles, and significantly increase the negative potential on the surface of the particles, so that the electric double layer is more stable and the dispersion effect is better.

Each pigment particle has an optimal dispersion state, and all the pigment particles happen to form a stable electric double layer structure. The dispersant is neither excessive nor lacking, and is in a critical state. The dispersant dosage at this time is the optimal dispersant dosage.

At present, the commonly used dispersants mainly include polyacrylates and polyphosphates. They are generally anionic. Among them, sodium hexametaphosphate is the most widely used, mainly used in porcelain clay, ground calcium carbonate, satin white, etc.