Elastomer Specialties, Inc. is a member of and agrees and complies with all definitions, specifications and mandates stated by the Polyurea Development Association (i.e. PDA). This PDA has been assembled to further the technology and proper application of polyurea for the greater good of the industry. The complete definition can be found on the Polyurea Development Association website at WWW.PDA-Online.org.
ESI has compiled a general Polyurea overview including terms and definitions, in laymen’s terms, for the engineers, architects, and contractors who may want to have a brief education and the proper information for specification and sales purposes.
A “Simple” Look at Definitions:
Polyurea can be defined as the result of a chemical reaction between an isocyanate and an amine. In polyurea coating terms, this is generally a reaction between an MDI or HDI pre-polymer with amine-terminated resins. This is also the formally excepted definition by the PDA. The PDA also allows the use of pigment dispersions in polyols (these are commonly used as colorants) assuming correct stoichiometric calculations have been used. These amines are generally comprised of polyetheramines (such as Jeffamine® D2000) and a primary amime chain-extender (such as Ethacure® 100) which is used to impart hardblock content and place the formulation on a 1:1 by volume ratio. Polyurea coatings can also be comprised of aspartic esters which provide amine functionality. A polyurea provides a chemical backbone containing amine linkages. Polyurea is generally used as an industrial coating in severe environments with good chemical resistance to hydrocarbons and hydrogen sulfide gas and immersed sewage applications.
Polyurethane can be defined as the result of a chemical reaction between an isocyanate and a polyol. It is important to realize that polyurethane requires the use of a catalyst to complete the reaction in a timely manner. As with polyureas, a pigment dispersed in a polyol is generally used for colorant. These formulations generally require various volume ratios and ambient temperatures. Usually these formulations have no amines in the polymer backbone. All functionality is considered to be hydroxyl (i.e. containing alcohols). Polyurethanes are generally used as casting materials and foams. They show good longevity and are relatively inexpensive.
Polyurea/Polyurethane hybrid formulations can be defined as the result of a chemical reaction between an isocyanate and a mixture of polyol and amine reactants. These formulations generally provide an “intermediate” polyurea that displays many of the same properties of a polyurea. However, hybrid formulations can also display some of the negative problems associated with polyurethane chemistry. In coatings formulation, hybrids generally contain a polyether/polyester polyol and a primary amine resulting in a chemical backbone comprised of amine and hydroxyl functionality. Polyurea/polyurethane hybrids are normally associated with use on “non-critical” items that generally do not require immersion or extreme temperature conditions for application. Some examples of these applications include sprayed-in truck bed linings and balcony deck coatings.
For a deeper discussion on the differences between the products, please go the Technical Article section of our Website.