polyurethaanharsen

Polyurethaanharsen, or polyurethane resins, are resinous components used in polyurethane coatings, adhesives and sealants. They are based on polyurethane chemistry and are designed to form durable, crosslinked films when cured. In practice, these resins are prepared from polyols and di- or polyisocyanates and may carry reactive terminal groups such as hydroxyl or isocyanate, which drive the curing reaction with a suitable hardener or crosslinker.

There are several types of polyurethaanharsen. Hydroxyl-functional PU resins (OH-PUR) cure with polyisocyanate hardeners to form the crosslinked network, often yielding coatings with good hardness and adhesion. Isocyanate-functional PU prepolymers (NCO-PUR) can react with active hydrogen compounds or moisture to achieve cure. The backbone can be based on aromatic or aliphatic structures, with aliphatic PU resins generally offering better UV stability and reduced yellowing compared with aromatic resins.

Formulations and processing methods vary. PU hardcoat systems are commonly two-component (2K), consisting of a PU resin and an isocyanate or polyol-based hardener. They can be solvent-borne, waterborne, or 100% solids, and may be designed for demanding environments such as automotive, wood, metal, or industrial coatings. The choice of resin type, degree of crosslinking and solvent system influences properties such as hardness, elasticity, chemical resistance and gloss.

Applications include coatings for wood and furniture, automotive refinishes, metal protection, industrial and marine coatings, as well as some adhesive and sealant formulations. Safety considerations are important: isocyanates pose health risks and proper handling, ventilation and protective equipment are recommended.

Overall, polyurethaanharsen provide durable, customizable binders that enable high-performance polyurethane finishes across diverse markets.