Differences Between PU and PIR Sandwich Panel

July 29, 2020by Fineagles

In the previous journal , Sandwich Panel itself and PU sandwich panel was explained. The
core of Sandwich Panel could be replaced by PIR (Polyisocyanurate). Even though both are
rigid foam with high thermal insulation properties, their physical properties and chemical
properties are different.

Chemical properties:

Rigid foam is formed by mixing four or more components in the metering machine or foam machine, main compensates of PU and PIR foam are Methylene Diphenyl Di-isocyanate (MDI,
commonly known as isocyanate or ISO) and POLY.

There are two types of polyol:

  • Polyethylene Glycol (PEG)
  • Polyester Polyol.

In simple terms: when ISO is mixed with Polyethylene Glycol (PEG), polyisocyanurate (PIR)
rigid foam is created as a chemical reaction and when Polyester Polyol is mixed with ISO,
polyurethane foam (PU). Of course, the presence of other components such blowing agent
and catalyst are very vital in order to have a perfect closed-cell rigid foam with effective
thermal insulation. Insulation is achieved by having almost 97% of the blowing agent gas
contained in the cells of the foam. Rigid foams are used to prevent energy loss and minimise
CO2 emissions applications that require thermic insulation.

Flame Resistance Properties:

One of the most major difference between PU and PIR rigid foam in sandwich panel is in the
flame resistance characteristic. PU foam is known for its limited fire resistibility, PU sandwich
panel is normally produced with B2 and B3 fire classification of building materials:

Class B: Combustible materials (such as textiles, furniture and other interior)
– Class B1: Flame Retardant
– Class B2: Normal Flammability
– Class B3: Easily Flammable (not usable in industrial Buildings)

On the other hand, PIR slows the spread of flames and reduces the smoke emitted from the
fire when compared to PU products. Generally, PIR sandwich panels have excellent fire
performance, reduced combustibility, and higher working temperature limits compared to
PU. PIR sandwich panels are produced with B1 fire classification of building materials. Indeed,
PIR sandwich panels pass compulsory fire tests without the addition of external flame

Production Differences:

For production of PIR sandwich panel with sandwich panel production line, same poly as PU
sandwich panel cannot be used. The poly used in metering machine has to be specifically
manufactured for PIR foam. In the production of PIR sandwich panel, the proportion of MDI
is higher, and instead of polyols on ethers, a polyether polyol is used in the reaction. The
catalysts and additives used to produce PIR are also different from those used in PUR.
Furthermore, heating in double belt of sandwich panel production line will be higher in PIR
sandwich panel. Double belt in the production of PIR sandwich panel line will reach around
60 centigrade while for PU sandwich panel it will be around 40 centigrade.

In the production line of the sandwich panel, un-coiler, roll forming, double belt, cutting
machine for sandwich panel, stacking sandwich panel cooling system of sandwich panel and
packing of sandwich panel will be the same. Foaming machine will have an extra tank for the
poly and corona system is added to the PIR sandwich panel production line to increase
adhesive properties of the metal sheet.



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