Polyisocyanurate

Polyisocyanurate ( PIR abbreviations ) are the polyurethanes ( PU) related plastics, which are ideal for thermal insulation. The proportion of diphenyl methane diisocyanate (MDI) is higher than for Pu. Furthermore, it is used in place of a polyether polyol a polyester polyol as a reactant. As a structural element in the PIR Isocyanuric occurs.

Production and Properties

The reaction of the MDI and the polyol is carried out at temperatures higher than in the production of polyurethane. At these elevated temperatures, the MDI reacts with itself to form strong chains of isocyanurate. This cross-linking is stronger than regular bonds in polyurethane and therefore harder to break. PIR is chemically and thermally stable than PU, starts to degrade above 400 ° C. PIR has a typical MDI / polyol ratio of from 2:1 to 5:1, wherein Pi is the ratio 1:1. The stiffness of the material does not increase linearly with the ratio.

Use

PIR is produced mainly as a foam and used in the form of rigid foam boards as a strong insulation for thermal insulation of buildings. Its thermal conductivity has a typical value of 0.023 W / mK, which is one of the lowest of conventional insulating materials.