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PUR(PU)
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PIR
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Main Ingredient
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polyurethane |
polyisocyanurate(basically an improved type of rigid
polyurethane PUR), because its production process
creates strong isocyanurate linkages in the molecular
structure. Chemical breakdown of the PIR foam occurs at
higher temperatures than PUR, so it is much more
difficult to ignite. |
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Advantages |
high
strength to weight ratio & thermal efficiency |
PIR combines
PUR benefits, such as rigidity, lightweight and thermal
efficiency, with the key addition of lower flammability. |
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Fire reaction |
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Degradation
of PIR commences at a higher temperature than PUR. A
fire would need to be much more seriously developed
before PIR foam might significantly contribute to the
spread of the fire through a building. PIR also forms a
surface char, helping to insulate the underlying foam
from the fire. |
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Chemical
Structure
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Made by
reacting the isocyanate (MDI) with certain types of
polyol, such as a polyether |
differs from
PUR in that it is produced using an excess of the MDI
component. In the presence of an appropriate catalyst
the excess MDI reacts with itself to form isocyanurate
which is characterised by greater heat stability |
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Chemical
Breakdown |
Breakdown
occurs at 230-250℃ |
For true PIR
foam with 50% or more isocyanurate linkages, breakdown
occurs at 400℃ |
