Throughout this page we will present you with information surrounding the history, chemistry and application methods including equipment required to form polyurea. We will also detail the difference between a true 100% pure polyurea and cheap hybrid/polyurethane products out there. Inseal Coatings is the only company that can prove their product is pure polyurea. Talk to us about our POLY-ID testing kit, a simple and quick method of determining a products ID i.e. polyurea, polyurethane or hybrid.
Polyurea – a Revolutionary Discovery
In the early 1980’s a young chemist, at the then Texaco group, was tasked with developing the companies SPF (spray polyurethane foam) product range. One day the chemist set about spraying some foam but realised that something wasn’t quite right when the dispensed material didn’t behave how SPF does. The chemist scratched his head (we assume!) in confusion and then took to his lab notes and traced back over his records. It was hear he discovered that polyether, rather than polyol, had been used for cross-linking with the iso component. Great value was seen in the flexible but tough coating, named polyurea due to its repeated urea linkage. The early application of polyurea was in the form of Reaction Injection Molding (RIM) to form automotive body parts. Since then extensive R&D has been spent on the formulation and equipment needed to process the fast cure product, which now has application in many fields. In the early days the polyurea gel time was so quick (<2 sec), and with equipment in its infancy, problems occurred with gear becoming blocked and insufficient time for the membrane to wet the substrate before cure. Polyurea has advanced since these early days and equipment is now state of the art.
What is Polyurea
In simple terms polyurea is the reaction product of two components, an isocyanate and resin blend. The components are heated and pressurised through special plural component equipment, then mixed and dispensed via impingement gun. Polymerisation takes place resulting in an elastomeric coating exhibiting outstanding physical properties.
The above illustration shows polyurea reaction formation. What distinguishes polyurea from other polymers such as polyurethane, can be found in the resin. A true polyurea is purely amine terminated (-NH2 in the polyamine).The reaction with the isocyanate forms a urea linkage. Polyurea contains NO catalyst, the reaction is self catalytic.
Pure Polyurea’s are 100% solids containing zero solvent, non-reactive diluents or VOC’s (volatile organic compounds). Their main advantage is the ability to cure rapidly over a broad temperature range (-40 to 100 degrees centigrade). This temperature range also has no effect on the coating when in service whereby it retains its full physical properties. The rapid cure nature allows fast return to service minimising down time which is key to asset owners. Polyurea can be walked on and rained on within minutes of application.
Polyurethane and hybrids
Over the years there has been some amlagamation of urethane and polyurea technologies forming polyurethane/polyurea hybrids. This has led to confusion of what polyurea actually is, as manufacturers promote their products as ‘pure polyurea’ when in fact they are modified polyurethane/polyurea i.e. hybrid. In the reaction of a polyurethane the resin is terminated with hydroxyl groups referred to as polyols (-NH2 is replaced by -OH in the above illustration). Polyurethane systems require a catalyst to drive the reaction, resulting in a urethane linkage. The catalyst is impeded by lower temperature and moisture reacts with the hydroxyl group causing issues with cure and physical properties. Polyols used in hybrid polyurethane coatings include polypropylene glycol and polypropylene oxide.