Selective Recycling of Steel Sandwich Polyisocyanurate (PIR) Foam Insulation Cladding

A method has been developed to delaminate the organic components (paint, foam) from the steel skins of composite polyisocyanurate (PIR) steel insulation panels at ambient temperature and in 20 min using selected solvents combined with ultrasonication. Using this method, polyisocyanurate foam can be selectively delaminated from polymer-based paint (PVC plastisol) and, in turn, the polymer paint can be selectively delaminated from the galvanised steel. Both the foam and paint are removed as intact layers, leaving the galvanised steel intact for the next steps of recycling, enabling the subsequent individualised recycling of each sub-component or layer. Several solvents have been tested, and the data show that H-bonding solvents (e.g., H2O, alcohols) are less effective at delaminating these polymers. Whilst high polarity, medium H-bonding acetonitrile and DMSO remove PVC paint and some PIR foam, the most effective solvent for both PIR foam and PVC paint removal is medium polarity, medium H-bonding acetone.