|Type of Surfactant||Application|
|PEG-Alkyd||Emulsifier / dispersant can be used in either oil or water|
|A-B-A Tri-Block copolymer||Emulsifier / dispersant for low polarity oils|
|Oligomeric||Emulsifier / dispersant for low polarity oils|
|Comb graft copolymers||Dispersants for solid particles in water|
The required level of polymeric emulsifier depends on the type of oil, the ionic content of the aqueous phase and the desired droplet size of the final emulsion. Start with 1% surfactant on the dispersed stage, if failing then increase to 5%.
The surfactant is usually dissolved in the oil phase if possible, with gentle warming and agitation when appropriate. In most cases it will be necessary to produce the emulsion in a high-shear mixer/emulsifier. The disperse phase should be added slowly to the continuous phase under agitation on the mixer.
The emulsification behaviour can be modified by the addition of other non-ionic surfactants, hence initial experiments to evaluate the benefits of using polymeric surfactants should try to minimize the level of such components.
The required level of polymeric dispersant depends on the surface area / particle size of the dispersed solid and the strength of the interaction between the dispersant the particle surface. Typically for metallic oxides with an average particle size of 1um and a surface area of ca. 5m2/g a dosage of 1-3% on weight of solid may be required. Organic compounds, metal particles and carbon may require as much as 5-10% on weight solid.
|Improved particle wetting||Efficient milling, saves energy, higher productivity, less wear|
|Increased solids loading||Low viscosity, higher productivity, better handling|
|Effective steric barrier / increased stability||Long shelf life, better handling, low storage loss|
|Viscosity reduction||Improved flow and rheology, energy savings|
|Compatibility with many resins/solvents||Multi-purpose dispersions, reduced inventories|
|Hydrophobic agent at the solid/liquid interface||Reduced water absorption, makes surface hydrophobic|
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