A process for preparing polyimide and polyimide thus prepared

Process for preparing a polyimide, comprising: introducing into an extruder (80) a mixture of oligomer consisting of 20 to 95 weight percent of a solventey 5 to 80 percent by weight of an oligomer formed by the reaction of a compound dianhidridoconstituido by bisphenol A dianhydride and diamine compound consisting of meta-phenylenediamine; in queel solvent is selected from the group consisting of halogenated aromatic solvents, solvents alifaticoshalogenados and mixtures thereof; removing the solvent from the oligomer mixture via a vent (100) in the extruder (80); yamasar melt the oligomer to form a polyimide.