Two-component polyurea systems typically do not contain any solvent or Volatile Organic Compounds (VOC). They are known for a very rapid dry time of less than 30 seconds without the use of a catalyst as in the two-component polyurethane systems. This rapid dry time is uniform over a very broad range of ambient temperature without being affected by ambient moisture. However, the presence of moisture on a substrate can negatively affect adhesion onto the substrate.
Polyureas have better thermal properties and higher melting point when compared to polyesters, linear polyethylene, polyurethanes, and polyamides. These properties thus allow for the painting of parts using the online Electrophoritic Paint Deposition (ELPO) process as the process involves operating temperature of 400°F (205°C).
The advantages or unique characteristics of polyurea over polyurethane and polyurethane/polyurea hybrid system in RIM (Reaction Injection Moulding) applications included rapid moulding/curing time which was typically 2 – 3 second set or gel times with a dry time of less than 10 seconds. However, its ultimate elastomer physical properties (up to 40MPa tensile strength and 500% elongation) can only be achieved at least 24 hours after application. Polyurea systems can be aliphatic or aromatic or both. Aliphatic polyurea systems have better resistance to degradation by ultraviolet light than that of aromatic polyurea.
For more information on polyurea and polyurethane formulation and processing, please refer to our partner Dr. Pooria Pasbakhsh from Monash University Malaysia.
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