Non ionic emulsions are selected when ionic interactions create instability or when substrates and additives cause unpredictable breaking. They can be useful in certain specialty coatings, primer systems, or formulations that include polymers, fillers, or additives that react badly with charged emulsifiers. Non ionic systems may also be considered when water chemistry varies widely and charge control is difficult. However, in mainstream road works, cationic and anionic emulsions dominate because they provide strong, predictable adhesion on common aggregates. If you consider non ionic grades, require strong stability data and real substrate trials before scale purchase.