extreme resistance

Polyurethanes are reaction polymers and are produced by reacting an isocyanate containing two or more isocyanate groups per molecule with a polyol containing on average two or more hydroxy groups per molecule in the presence of a catalyst or by activation with ultraviolet light.

The properties of a polyurethane are greatly influenced by the types of isocyanates and polyols used to make it. Long, flexible segments give a soft elastic polymer.

High amounts of crosslinking give tough or rigid polymers. Long chains and low crosslinking give a polymer that is very stretchy and short chains with lots of crosslinking produce a hard polymer.

The crosslinking present in polyurethanes means that the polymer consists of a three-dimensional network and molecular weight is very high. Polyurethane coatings do not soften or melt when they are heated – they are so called thermosetting polymers.