Process for preparing a coated 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, c) subjecting the surface of the object to a surface energy increasing treatment step, which involves corona discharge treatment, plasma treatment and/or surface flaming, and d) coating the surface of the object with a layer after the 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) in which R 1 is a C 18 H 37 group or is a phenyl group substituted with two tert.-butyl groups, and characterized in that the polypropylene resin further comprises B) at least one primary antioxidant, in particular selected from the group consisting of a sterically hindered phenol or a sterically hindered amine, and characterized in that the polypropylene resin further comprises C) at least one acid scavenger, in particular selected from the group consisting of a hydrotalcite, a metal stearate and a metal oxide. a) providing a polypropylene resin, b) forming an object of said polypropylene resin, c) subjecting the surface of the object to a surface energy increasing treatment step, which involves corona discharge treatment, plasma treatment and/or surface flaming, and d) coating the surface of the object with a layer after the surface energy increasing treatment step, 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) in which R 1 is a C 18 H 37 group or is a phenyl group substituted with two tert.-butyl groups, and characterized in that the polypropylene resin further comprises 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 R 1 is a C 18 H 37 group or is a phenyl group substituted with two tert.-butyl groups, and characterized in that the polypropylene resin further comprises B) at least one primary antioxidant, in particular selected from the group consisting of a sterically hindered phenol or a sterically hindered amine, and characterized in that the polypropylene resin further comprises C) at least one acid scavenger, in particular selected from the group consisting of a hydrotalcite, a metal stearate and a metal oxide. <EOS>