Aliphatic Polyisocyanates Center

1K & 2K Systems

Polyurethanes based on aliphatic polyisocyanates are renowned for their outstanding properties and especially for their exceptional resistance to weathering and chemical attack. Two main categories of polyurethane systems can be distinguished: two-component (or 2K) and heat-activated, one-component (or 1K).


2K polyurethane coatings

Two-component systems consist of a polyisocyanate and a polyol that are mixed just prior to application and cure at room temperature. In volume terms, this family accounts for over half of all urethane coatings sold in the world.

The crosslinking reaction (-NCO + -OH) occurs on the substrate at room temperature, but sometimes, stoving 30 min at 60°C or 80°C is used to speed up drying (for productivity reasons) .

Therefore, 2K polyurethane coatings are used :

  • on substrates sensitive to heat (plastics, wood, cars....),
  • on objects too big to be stoved (trains, airplanes, bridges...).


2K polyurethane coatings

One-component PUs are similar materials to the previous one, except that a blocked isocyanate is used to provide a storage stable one-pack formulations containing the polyol. After application of the coating on the substrate and during stoving at elevated temperature, the isocyanate is de-blocked and then it reacts with the polyol to form the PU network. This includes powder coats, which consume now over 10% of all urethane in paints


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