Very high solid systems with polyaspartics (polyaspartic acids)
Polyaspartics (polyaspartic acids) represent a class of binders that combine low VOC properties with high productivity, while at the same time maintaining the quality requirements users expect from polyurethane coatings.
Low VOC content - Environmental friendlyness
Reducing solvent emissions to a minimum has been an ongoing objective to develop environmentally friendly coatings systems and to comply with current VOC regulations. The low viscosity properties of polyaspartic binders - some down to below 100 mPas - make it possible to formulate "ultra high solid" coatings that can still be applied easily with the equipment regularly used in corrosion protection and industrial coating areas.
Meeting increased cost pressure
There is a growing tendency to reduce cost to the endusers of corrosion protection and other industrial coating applications. This can be met by increasing the productivity of the entire coating process. Polyaspartics make it possible to contribute to cost efficiency in two ways:
Reduced drying times
Coating systems based on polyaspartic acids are dry in 1 1/2 to 4 hours at room temperature, depending on the environmental conditions. So the application of the layers is accelerated significantly.
Greater film thickness
A dry film of up to 400 µm thick can be obtained in a single coating operation, so the number of coating layers can be reduced, in many cases by one layer in the entire coating built-up.
Maintaining high quality
On top of the environmental requirements and the need to reduce cost the property profile of the coatings still needs to be at the same high level people expect from polyurethane systems. The protective properties are critical for the longevity of steel structures and a good gloss retention is desirable even in severe weather exposure. In general, the typical high quality performance of polyurethane coatings are easily met (i.e. durability, flexibility, ect.) with polyaspartics on a variety of different substrates.
Polyaspartic acids are cured with aliphatic polyisocyanates. The potlife and reactivity of the formulation can be finetuned exactly by selecting the appropriate Desmophen® NH component. Some suitable polyisocyanate crosslinkers (Examples)
About the chemistry of polyaspartics (polyaspartic acids)
A polyaspartic is an aliphatic polyurea (reaction product of an aliphatic polyisocyanate with an aspartic ester). Aspartic esters are sterically hindered, secondary aliphatic amine. However, coatings based on polyaspartics are very different in both application and coating performance properties from conventional polyureas.
Polyaspartics are not blocked, they are odorless and compatible with most other resins. Due to their aliphatic character the coatings exhibit a good weatherability.
This technology is primarily used in coatings for corrosion protection, for commercial vehicles, ACE (Agricultural, Construction, Earth Moving Equipment), in windmill power plants and in the construction industry, to just name a few examples.
