| abstract |
In a process of preparing a polyisocyanurate foam, which process comprises: reacting a plasticized polyisocyanate in the presence of a trimerization catalyst and an expanding amount of an inert blowing agent to provide a polyisocyanurate foam, the improvement which comprises: carrying out the reaction in the presence of from about four to twenty percent by weight of a surface-active organic silicone compound characterized by an active hydrogen functionality, and having a hydroxyl number of greater than about 30 and an equivalent weight of less than about 2000 and in the presence of a nonvolatile plasticizer to provide a polyisocyanurate foam of improved friability and good flame, heat and stability properties. |