Process for preparing a polypropylene-based object having an increased surface energy The present invention relates to a process for preparing a polypropylene-based object having an increased surface energy, said process comprising the subsequent steps of a) providing a polypropylene resin, b) forming an object of said polypropylene resin, and c) subjecting the surface of the object to a surface energy increasing treatment step, Characterized in that the polypropylene resin comprises A) at least one secondary antioxidant of formula (I) in which n is 0 or 1, each R may be the same or different and is an unsubstituted phenyl group or a phenyl group substituted by one or two alkyl groups having from 1 to 12 carbon atoms, and X is a residue of a monofunctional or difunctional phenyl group, diphenyl group, diphenyl ether group or dibenzofuranyl group and/or of formula (II)