What Is Polyurea

Polyurea Overview

Polyurea is a type of elastomer derived from the reaction product of an isocyanate component and a synthetic resin blend component through step-growth polymerization. The isocyanate can be aromatic or aliphatic in nature, and may be a monomer, polymer, or any variant reaction of isocyanates, quasi-prepolymer, or prepolymer. The prepolymer or quasi-prepolymer can be made of an amine-terminated polymer resin or a hydroxyl-terminated polymer resin.

The resin blend may consist of amine-terminated polymer resins and/or amine-terminated chain extenders. The amine-terminated polymer resins do not contain intentional hydroxyl moieties; any hydroxyls present result from incomplete conversion to the amine-terminated polymer resins. The resin blend may also contain additives or non-primary components, such as pre-dispersed pigments in a polyol carrier. Typically, the resin blend does not contain catalysts.

Uses

Polyurea and polyurethane are copolymers used in the manufacture of spandex, invented in 1959. Polyurea was originally developed to protect tabletop edges, leading to the development of two-component polyurethane and polyurea spray elastomers in the 1990s by Mark S. Barton and Mark Schlichter (US 5534295 patent). Its fast reactivity and relative moisture insensitivity make it ideal for coatings on large surface area projects, such as secondary containment, manhole and tunnel coatings, tank liners, and truck bed liners. Excellent adhesion to concrete and steel is achieved with proper Primer and surface treatment. Polyurea can also be used for spray molding and armor. Some polyureas achieve tensile strengths of 40 MPa (6000 psi) and over 500% elongation, making them tough coatings. The quick cure time allows multiple coats to be built up rapidly.

In 2014, a polyurea elastomer-based material was shown to be self-healing, melding together after being cut in half. The material uses inexpensive commercially available compounds. By tweaking the elastomer molecules to lengthen the bonds between them, the resulting molecules are easier to pull apart and better able to rebond at room temperature with nearly the same strength. This rebonding can be repeated. Stretchy, self-healing paints and coatings have moved closer to common use, thanks to research at the University of Illinois, where scientists used off-the-shelf components to create a polymer that melds back together after being cut in half without additional chemicals.

Polyurea has become a preferred long-term solution for narrow boats. Traditional bitumen coating, known as "blacking," is being replaced by Polyurea Coatings. The clearest advantage is that reapplication every 3–4 years is unnecessary; polyurea coatings are estimated to last 25–30 years.