Process for producing thermosetting resins

A process for producing a thermosetting resin which comprises blending 1 equivalent of a polyoxazolidone prepolymer terminated by two vicinal epoxy groups and containing at least two oxazolidone rings with at least 1 equivalent of a bifunctional isocyanate compound, adding 0.01 to 10% by weight of a catalyst which forms isocyanurate rings and oxazolidone rings based on the total amount of the polyoxazolidone prepolymer and the isocyanate compound, and then heating to polymerize the resultant composition by forming isocyanurate rings and oxazolidone rings.

A process for producing a thermosetting resin which comprises blending 1 equivalent of a polyoxazolidone prepolymer terminated by two vicinal epoxy groups and containing at least two oxazolidone rings with at least 1 equivalent of a polyfunctional isocyanate compound, adding 0.01 to 10% by weight of a catalyst which forms isocyanurate rings and oxazolidone rings based on the total amount of the polyoxazolidone prepolymer and the isocyanate compound, and heating the resultant composition to cause (a) formation of isocyanurate rings by effecting trimerization of said isocyanate compound and thereafter (b) polymerization of the composition by formation of oxazolidone rings.

A process for producing a thermosetting resin which comprises blending 1 equivalent of a polyoxazolidone prepolymer terminated by two vicinal epoxy groups and containing at least two oxazolidone rings with at least 1 equivalent of a bifunctional isocyanate compound, adding 0.01 to 10% by weight of a catalyst which forms isocyanurate rings and oxazolidone rings based on the total amount of the polyoxazolidone prepolymer and the isocyanate compound, and heating the resultant composition to cause formation of isocyanurate rings by effecting trimerization of said isocyanate compound and thereafter (b) polymerization of the composition by formation of oxazolidone rings.