Rhone-poulenc Chimie

Andre Blind

Jean Robin

Gerard Collas

Ferenc Sagi

Substantially pure isocyanurate/polyisocyanates, i.e., containing no more than about 0.03% by weight of residual diisocyanate monomer and no more than about 1% by weight of diisocyanate dimer, are produced by extracting impure cyclotrimerized diisocyanates with an inert gas in either the liquid or supercritical state.

Substantially pure isocyanurate/polyisocyanates

Isocyanate condensates containing free NCO groups are separated and purified from crude reaction mixtures thereof which include unreacted excess di- or polyisocyanate monomer and at least one isocyanate antagonist, by extracting such crude reaction mixtures with an inert gas, notably carbon dioxide, in either the liquid or supercritical state; the highly purified isocyanate condensates are well adopted for the production of foams, elastomers, adhesives, paints and varnishes.

Isolation/purification of isocyanate condensates by extraction with

Polyisocyanates containing only trace amounts of free aromatic diisocyanates are recovered by purifying and isolating an isocyanate condensate containing free NCO groups from an impure admixture thereof, said isocyanate condensate impure admixture having been prepared by reacting a stoichiometric excess of an aromatic di- or polyisocyanate with a reactant compound containing at least two functional groups which are reactive with NCO groups, and such purification/isolation entailing extracting unreacted excess di- or polyisocyanate from said impure admixture with an inert gas, e.g., carbon dioxide, in either the liquid or supercritical state.

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Caluire, France

Andre Blind