The American West as Living Space

This invention is concerned with an improved polyimide which makes an excellent electrical insulation for metal conductors. It may be used as the insulating layer around the periphery of the metal conductor or as an adhesive for tape used as the insulating layer. The invention is also concerned with a novel prepolymer which is essentially a polyamide in structure and which is readily curable to the corresponding polyimide. The prepolymer is prepared by reacting a tetraalkyl ester of benzophenone tetracarboxylic acid or its anhydride with 1,3-bis(p-aminophenoxy)benzene.