Surfactants also act as lubricating agents as grinding aids

2021-11-12 17:07:47

Surfactant can reduce the interfacial tension and reduce the wetting angle θ Close to zero, the solid powder can be spontaneously dispersed in the surfactant solution. At the same time, the surfactant can help the liquid to wet the inner surface of the solid, make the liquid penetrate into the channels and voids between the aggregates inside the particles, provide a certain pressure, and destroy the strengthening bond force of the particle aggregates under the action of machinery.

At the same time, surfactant can help grinding, reduce the surface energy of particles and prevent the damaged surface from restoring bonding, so as to prevent particle coalescence. As a grinding aid, surfactant also plays a lubricating role, which can improve the specific surface area of products, shorten the grinding time and improve the grinding efficiency. Its mechanism can be summarized as follows: reducing crushing energy, increasing brittle fracture probability, preventing plastic deformation, controlling flocculation and aggregation of fine particles, strengthening dispersion and adjusting the rheology of slurry, etc.

The paint may produce high surface tension during spraying and maintain the high surface tension until sprayed onto the bottom, so the initial wetting effect is not good. Surfactants can be used to change this state, but attention must be paid to their selection, because the amplitude and speed of surfactant reducing dynamic surface tension are different.

Water soluble surfactants have little effect on reducing dynamic surface tension, but are not easily soluble in water. Surfactants forming micelles are often very effective. For example, sodium Diisooctyl succinate sulfonate and Pluronic L61 (a product of BASF Wyandotte company, an adduct of polypropylene glycol and ethylene oxide, a non-ionic surfactant) are not easily soluble in water, and the dynamic surface tension can be reduced to 4.3 and 3.6dyne/cm respectively in acrylic resin emulsion paint. Water soluble surfactants such as sodium dodecyl sulfate and sodium dodecyl benzene sulfonate can only move in this coating system. The surface tension decreased to 13.4 and 13.7 dyne / cm.