Silicone additive used as pigment filler dispersant
In order to disperse the pigments uniformly and prevent settling, dispersant is indispensable. In terms of structure, the dispersant contains pigment - friendly groups and solvated chain segments. After reasonable structure design, silicone compound can be used as dispersant of coating system. Common silane coupling agents can be used as dispersants of fillers, and sometimes in order to meet higher requirements, some special structures can be designed to achieve better results. Formula (6) is a schematic diagram of an organic silicon compound used as a dispersant for waterborne coatings.
Because usually fillers surface (especially the inorganic fillers) adsorption of moisture in the air or the structure of the reason, contain certain hydroxyl, when the organic silicon compounds to join water-based coating system, the organic silane can produce corresponding silicon hydroxyl, hydrolysis can produce silicon hydroxyl and hydroxy further condensation on the surface of the pigment, which tightly connected to the paint surface, In fillers surface molecular adsorption layer, coupled with its containing hydrophilic solvation chain segment stability provided by the entropy function, can provide fillers in water system with stabilization effect, so it is especially applicable to some of the more difficult to disperse the inorganic fillers, especially of nanoscale inorganic fillers, such as iron oxide, nano zinc oxide, nano silica) scattered.