Why amines and alkaline components are incompatible

P–OH is distinctly acidic. Contact with amines — amine hardeners, amine synergists, ammonia — forms phosphate salts. The molecule loses its interfacial activity and adhesion promotion essentially disappears.

In two-component epoxy, the acid consumes hardener, unbalancing the ratio and shortening pot life. In UV systems it neutralizes amine synergists and degrades surface cure.

Basic fillers behave the same way: zinc oxide, calcium carbonate and alkaline pigment pastes react with phosphate groups, causing thickening and gelling on storage.

If the formula does contain alkaline components: add the phosphate to the component without them, apply it as a separate primer, or switch to a non-amine initiation system.

Related question: phosphate esters cannot be used in amine-cured epoxy or isocyanate-cured polyurethane — the former neutralizes, the latter reacts with NCO releasing CO2.