Little Known Polyurea Faq's





Q? IS POLYUREA HARD OR SOFT?
A. Polyurea may be either hard or soft depending on the particular formulation and the intended use. Durometer ratings may range from Shore A 30 to Shore D 80.


Q? WHAT IS POLYUREA’S ABRASION RESISTANCE?
A. ArmorThane has run abrasion resistance testing according to ASTM D 4060 using the most aggressive abrader, the H-18 wheel. The abrasion loss is as noted in our material specification data sheets for the appropriate material. This test was utilized because it most nearly typifies the type of abrasion
attack found in industrial environments.
The industry standard testing for polyurethanes uses the abraser CS-17 wheel. This wheel is a much smoother, less abrading mechanism than the above-mentioned H-18 abrader wheel. The most severe utilization of polyurethanes is found on parking deck coating systems.
The hard polyurethane topcoats used in these systems generally have CS-17 losses between 5 – 10 milligrams. FSS 45DC and FSS 50DM report H-18 loss between 180 and 250 milligrams. This loss is much less severe than a loss of 5 – 10 milligrams on the CS-17 wheel.



Q? HOW WELL DOES POLYUREA ADHERE TO STEEL?
A. ArmorThane polyurea may be applied to adequately prepared A-36 metal substrates. The metal should be blasted to Near White or White, and have a blast profile of 5 mils. Adhesion values will exceed 1000 psi without using a primer.
Q? WHAT FACTORS SHOULD BE CONSIDERED WHEN ADHERING TO CONCRETE? A. No hard and fast number is useful to the designer. Generally, an adhesion value is a compromise between the type and condition of the concrete substrate, the stresses placed upon the membrane before project completion, and the requirements of the layer to withstand in-place use stresses. Where possible, concrete should have all surface paste removed and be free of laitance of any kind. Texture similar to 80-grit sandpaper as a minimum is desirable.
Since concrete has low tensile properties, especially at the surface faces of large plan areas, one rule of thumb is to expect adhesion to range around ten percent (10%) of ultimate compressive strength of the concrete. The best that can be expected is in the range of 350 psi to 450 psi for 4,000 psi concrete properly cured and of sufficient age to acquire its maximum physical properties.


Q? SHOULD THERE BE CONCERN THAT POLYUREA CONTAINS ISOCYANATE?
A. Polyurea products from ArmorThane are based on diphenylmethane diisocyanate (MDI) or 1,6 hexamethylene diisocyanate (HDI) polymer technology. These polymers have a low vapor pressure, which corresponds to a flat evaporation rate.
During the mixing, installation and curing process of all Polyurea, the release of any free monomers is virtually non-existent. The chemical design of these products entails an extremely rapid reaction between the molecules in each component. This quick reaction, coupled with the lack of any evaporative characteristics, allows these products to fall well within safety guidelines established under OSHA and ACGIH. The installation of these products may be made in incidental food contact locations and are certified under the FSIS procedures of the USDA.
Self-leveling polyurea products have been tested under field conditions during application for CalTrans (California Department of Transportation), with the detection of no free molecules in the environment. Review of MSDS information is recommended before handling of any products. When polyurea products are spray applied, use of an OSHA/NIOSH approved respirator should be a standard required procedure.



Q? HOW SHOULD POLYUREA BE PREPARED FOR OVERCOATING AFTER INITIAL CURE OF THE POLYUREA?
A. Before overcoating Polyurea makes sure, it is clean. For the first several hours after Polyurea has gelled, it may be suitable for overcoating without further preparation. If polyurea base coat material has been in place for longer than six hours, there could be problems with inter-coat adhesion.
Since fewer products are carried in an aromatic solvent, which tacktify Polyurea, you must undertake this process, to assure inter-coat bond apply a liberal amount of denatured alcohol (or more aggressive solvent such as acetone or MEK) to Polyurea and allowed to evaporate completely. This will re-tack the polyurea base coat and allow proper adhesion of the follow-on overcoat. This same procedure should be used when bonding Polyurea to Polyurea after an initial cure has taken place.


Q? WHAT’S THE DIFFERENCE BETWEEN AROMATIC AND ALIPHATIC POLYUREA SYSTEMS?
A. There are two different types of aliphatic polyurea systems currently on the market. One is the average high pressure/temperature, and the other is what is known as a “polyaspartic polyurea” type system. This polyaspartic system is different in that it uses an ester based resin component and has a longer pot life. It can be hand applied using close nap rollers; brushes; rakes or even airless sprayers.
The aspartic systems are not the high build coating typical of the “hot spray” polyurea systems. The unique aromatic polyurea systems must be processed through high pressure, heated plural component pumps, and sprayed through an impingement type spray-gun. This is true also for the aliphatic version of this type of system, the primary difference being the color stability of the aliphatic systems.
Q? WHICH ASTM STANDARDS ARE USEFUL WHEN PREPARING CONCRETE SURFACES?
A. The following ASTM standards can be a useful guide when you prepare concrete surfaces.
Standard Practice for Surface Cleaning Concrete for Coating (D 4258)
Standard Practice for Abrading Concrete for Coating (D 4259)
Standard Practice for Acid Etching Concrete (D4260)
Test Method for pH Chemically Cleaned or Etched Concrete Surfaces (D 4262)
Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method (D 4263)
Test Method for Indicating Oil or Water in Compressed Air (D 4285)
Standard Practice for Surface Preparation of Concrete for Application of Chemical-resistant Resin Monolithic Surfacings (C 811)
For more information on these or other ASTM standards, visit www.astm.org.


Q? WHAT MAKES POLYUREA “GREEN”?
A. “Green Technology” is a familiar phrase in our daily vernacular, but did you know that there are many requirements to meet to call a product “Green”?
In the May 2008 issue of Coatings World, an article attributed to Anastas and Warner, “Green Chemistry Theory and Practice,” Oxford University Press, New York 1988, the authors submit 12 Principles of Green Chemistry.
The common understanding of “green” chemistry focuses on the source material, and how much of the finished good can be recycled at the end of the products life. These attributes are only part of the green picture, and additional criteria can be met for Polyurea to be considered “green.”
ArmorThane pure polyurea contains zero solvents. The systems are entirely reactive when properly applied. There is no, and the resulting membrane forms an inert and non-hazardous product.
Polyurea is processed in a closed system, with minimal human or environmental contact. Of course, the applicator at the end of the spray gun is required to meet safety requirements as specified by the manufacturer and Polyurea Development Association (PDA). Studies have been submitted
measuring the rapid decrease in free isocyanate as one moves away from direct spray application. (PDA safety CD)
The manufacturing of the base materials going into an ArmorThane polyurea formulation is all handled at ambient temperature and pressure, requiring minimal energy input during production.
Minimal waste is generated during spray of Polyurea and clean up requires only minimum amounts of solvent, which can be recycled. Pure ArmorThane Polyurea contains no catalysts which would remain in the environment or break down over time.
The applied ArmorThane polyurea systems are noted for their superior corrosion and erosion protection for substrates, preserving the structure and the surrounding environment. As well, the coating will last longer, extending the service life and decreasing the need to generate new waste from surface preparation and coating work.
ArmorThane is proud to participate in the stewardship of our environment and continues to search for additional ways we can offer products which will meet the needs of your community.

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