polyurea

Polyurea is a class of polymer formed by the rapid reaction of an isocyanate component with an amine or another active hydrogen compound, yielding a network containing urea linkages. In coatings and sealants, polyurea is typically produced as two-component systems consisting of an isocyanate-terminated resin and a curative amine or amine-terminated resin. The reaction occurs quickly at ambient conditions, enabling spray-applied coatings that cure within seconds to minutes to form elastomeric, watertight films.

Two main families exist: aromatic polyurea and aliphatic polyurea. Aromatic variants tend to be cheaper and have high chemical resistance but may yellow or degrade under UV exposure; aliphatic polyurea offers better UV stability and color retention, though at higher cost. The resulting films are notable for their toughness, elongation, good abrasion and chemical resistance, high adhesion to concrete and metals, and very low water permeability. They can be applied in thin or thick coatings, often by spray, and can seal irregular substrates.

Common applications include protective coatings for concrete floors and tunneling linings, tanks and pipelines, offshore platforms, storage vessels, and waterproofing membranes. Spray polyurea coatings are valued for rapid return-to-service and resistance to immersion, freeze-thaw, and chemical attack, though successful performance depends on surface prep and controlled curing conditions.

Health and safety concerns center on isocyanates, requiring ventilation, PPE, and trained handling. Storage and safety data sheets govern use. Limitations include the need for specialized equipment and skilled installers, and UV sensitivity depending on formulation.