Paint dispersant is a kind of pigment filler dispersed in water or resin and can form a stable fine dispersed suspension of the material. Coating dispersant action mechanism includes: DLVO diffusion double electric layer stability mechanism, space steric resistance mechanism, electrostatic space stability mechanism three. That is, the dispersant adsorb on the surface of the pigment to generate a large amount of charge repulsion or provide enough space hindrance to prevent the pigment flocculation, so that the pigment system is in a stable state of dispersion.
The preparation of auxiliaries for coating is an important application field of controllable active polymerization technology. At present, large foreign auxiliaries companies have developed dispersants prepared by controllable active polymerization technology, and the corresponding products have been introduced to the market. Clemens Auschra et al. of Ciba Used the controllable active polymerization technology to prepare the block copolymer with methacrylate as anchor chain segment and butyl acrylate as solventated chain segment. The effect of the length of anchor and solventized chains on the dispersion of block copolymer dispersants was investigated. With the growth of the two chain segments, the molecular weight of the copolymer increases, the dispersant of the two pigments to enhance the dispersion, pigment paste has good rheological properties, and can improve the film gloss after curing. Compared with conventional acrylic dispersants and polyurethane dispersants, the dispersants prepared by controlled polymerization have good compatibility in both low and high polarity coatings. In most systems the color paste can even be transferred by hand, which provides a greater convenience for the formulation designer. In terms of gloss performance, this kind of dispersant showed better luster in all systems, which indicated that the controlled polymer dispersant had better pigment dispersibility and stability. In addition, the domestic researchers have done the related exploration in this regard, MuYingDeng using nitrogen oxygen free radical polymerization with the butyl acrylate is prepared - b - N, N - block copolymer of dimethylamine ethyl acrylate as monomer, adopted at the same time on the anchoring group of amino acid modified, make the anchoring group a cationic ammonium salt, Improve its applicability to pigments. Compared with conventional dispersants, the dispersant showed excellent stability and rheological properties of dispersion system for carbon black. When the additive amount was ≥50%, the color paste was almost close to the ideal Newtonian fluid. The high gloss and vividness of the film are improved obviously because the flocculation is avoided. Using ATRP method, Chai Yue-e synthesized AB block dispersant with polyethylene glycol monomethyl ether as solvent chain and polystyrene as anchor group, and discussed its influence on the dispersant of carbon black in water. By adjusting the proportion of two chain segments and the addition of dispersant, better dispersion effect can be obtained, and the flocculation of carbon black particles can be effectively reduced, and the particles are uniform and the average particle size is small. Compared with traditional dispersing agent, the dispersing paste has better storage stability.