<p>A resin composition comprises a product produced by the reaction of (a) a prepolymer prepared by reacting a diisocyanate with a hydroxy fatty acid ester or a mixture of a hydroxy fatty acid ester and a polyether polyol, with (b) at least one member selected from aromatic polyamines, polyether polyamines and polyether polyimines or a mixture of such a member as above and a polyether polyol. The resin composition is useful as an internal release agent for resins for reaction injection molding.</p>
