Bayer MaterialScience Introduces IPDI-based Hardener For Low-Emission Polyurethane Coatings

Conventional polyurethane coatings with a medium solids content often use a favorable combination of hardeners derived from two different diisocyanates: a hexamethylene diisocyanate (HDI) hardener ensures good cross-linking and resistance properties of the resultant coatings, while an isophorone diisocyanate (IPDI) hardener accelerates physical drying. Bayer MaterialScience has now developed an IPDI-based hardener, Desmodur® XP 2565 that greatly reduces the solvent content of polyurethane coatings. High-solids coatings can now be formulated with particularly fast drying properties. "This makes the hardener perfect for vehicle repair coatings, but other polyurethane coating systems that are used for applications like industrial goods can also benefit," says Dr. Raul Pires, who is in charge of transportation and vehicle repair coatings at Bayer MaterialScience.

In Desmodur XP 2565, Bayer MaterialScience has found another answer to the growing demand for raw materials used in low-solvent, high-solids polyurethane coatings. The market is reacting to stricter regulations that aim to reduce emissions of volatile organic compounds (VOC).

Waterborne polyurethane systems, ideal candidates for the new hardener, are also becoming increasingly popular because of their environmental friendliness.

Due to its low viscosity, the hardener can be mixed in the aqueous phase, but because it is not hydrophilically modified, it can be used to formulate aqueous coatings that are particularly weather-stable and chemically resistant. "With Desmodur XP 2565, paint companies have the first IPDI-based hardener for fast-drying, waterborne polyurethane coatings," says Dr. Martin Melchiors, an expert in polyurethane coating raw materials at Bayer MaterialScience.

Desmodur XP 2565 is an allophanate and more stable than many other low-viscosity polyisocyanates. It complies with the requirements of the European Inventory of Existing Chemical Substances (EINECS) and the Toxic Substances Control Act (TSCA) and therefore can be marketed all over the world.