Description

Polyisocyanurate, also referred to as PIR or ISO, is essentially an improvement on polyurethane (PUR). Different catalysts are used and the proportion of methylene diphenyl diisocyanate (MDI) is higher than for PUR. Instead of a polyether, a polyester derived polyol is used in the reaction.

Manufacturing

The reaction of polyol and MDI takes place at higher temperatures compared to the reaction temperature for the manufacture of PUR. As a result the MDI will also react with itself, producing strong chains of isocyanurate. These cross links are stronger than normal bonds in polyurethane. Therefore they are more difficult to break. As a result PIR foam is chemically and thermally more stable (disintegration starts above 400degC).

PIR typically has an MDI/polyol ratio over 400. This is defined by an ISO standard: ISO-....

Uses

PIR is typically produced as a foam. PIR is used for thermal insulation, the thermal conductivity has a value of 0.023 W/mK. PIR foam panels coated with pure embossed aluminium (U.S. sp. 'aluminum') foil are used for fabrication of pre-insulated duct that is used for heating, ventilation and air conditioning systems.

Health Hazards

PIR insulation can be a mechanical irritant to skin, eyes, and upper respiratory system during fabrication (such as dust). No statistically significant increased risks of respiratory diseases have been found in studies.

External links

• Polyisocyanurate Insulation Manufacturers Association
• Material Safety Sheet by Dyplast for PIR insulation sheet