Can we reduce the curing time of our paints still further via the isocyanate content?
Experience has shown that modification of conventional paints, especially those based on alkyd resins, with isocyanate adducts causes a considerable reduction in drying time. Aromatic compounds such as toluylene di-isocyanate (TDI) and diphenylmethane di-isocyanate (MDI) have proved particularly suitable in this respect since they result in increased reactivity, i.e. faster film formation compared with aliphatic compounds such as hexamethylene di-isocyanate(HMDI).
The latter, however, may be used where there is a risk of yellowing. It will often be advantageous, especially for reasons of factory hygiene, to use high molecular weight adducts such as are obtained by trimerisation. Paints modified in this way crosslink through oxidation, a process which can be helped along also with conventional driers. General purpose products such as cobalt compounds may be used as well as manganese, zirconium or aluminium compounds as well as multimetal driers.
Drying of Isocyanate-Modified Paints
Blog, Updated at: 3:28 PM
