Process for the production of a polypropylene based article having improved surface tension retention, said process comprises the steps of A) providing a metallocene-catalysed propylene-ethylene random copolymer (RACO) having (a) an ethylene content, determined by NMR spectroscopy as described in the description in section "Measuring methods", in the range of from 1.0 to 10.0 wt.-% based on the total weight of the propylene-ethylene random copolymer; (b) a melt flow rate MFR 2 (230°C/2.16kg) measured according to ISO 1133 in the range of from 1.0 to 20.0 g/10min; (c) a melting temperature Tm, determined by DSC according to ISO 11357 as described in the description in section "Measuring methods", of from 115 to 150°C; (d) a xylene cold soluble (XCS; ISO 16152, 2005; 25°C) fraction of from 0.1 wt.-% to 5.0 wt.-% and (e) a content of 2,1 regio-defects in the range from 0.05 to 1.5 mol %, determined by 13 C-NMR spectroscopy as described in the description in section "Measuring methods"; B) forming an article out of the metallocene-catalysed propylene-ethylene random copolymer (RACO) with a thickness in the range of from 1.0 to 1000 μm and C) subjecting one or more surface(s) of said article to a treatment that increases the surface tension, to yield a polypropylene based article having improved surface tension retention, wherein the surface tension increasing treatment of step C) is a chemical treatment, a Corona-treatment or a flame-treatment, and wherein the metallocene-catalysed propylene-ethylene random copolymer (RACO) is the sole polymer used for forming the article. A) providing a metallocene-catalysed propylene-ethylene random copolymer (RACO) having (a) an ethylene content, determined by NMR spectroscopy as described in the description in section "Measuring methods", in the range of from 1.0 to 10.0 wt.-% based on the total weight of the propylene-ethylene random copolymer; (b) a melt flow rate MFR 2 (230°C/2.16kg) measured according to ISO 1133 in the range of from 1.0 to 20.0 g/10min; (c) a melting temperature Tm, determined by DSC according to ISO 11357 as described in the description in section "Measuring methods", of from 115 to 150°C; (d) a xylene cold soluble (XCS; ISO 16152, 2005; 25°C) fraction of from 0.1 wt.-% to 5.0 wt.-% and (e) a content of 2,1 regio-defects in the range from 0.05 to 1.5 mol %, determined by 13 C-NMR spectroscopy as described in the description in section "Measuring methods"; (a) an ethylene content, determined by NMR spectroscopy as described in the description in section "Measuring methods", in the range of from 1.0 to 10.0 wt.-% based on the total weight of the propylene-ethylene random copolymer; (b) a melt flow rate MFR 2 (230°C/2.16kg) measured according to ISO 1133 in the range of from 1.0 to 20.0 g/10min; (c) a melting temperature Tm, determined by DSC according to ISO 11357 as described in the description in section "Measuring methods", of from 115 to 150°C; (d) a xylene cold soluble (XCS; ISO 16152, 2005; 25°C) fraction of from 0.1 wt.-% to 5.0 wt.-% and (e) a content of 2,1 regio-defects in the range from 0.05 to 1.5 mol %, determined by 13 C-NMR spectroscopy as described in the description in section "Measuring methods"; B) forming an article out of the metallocene-catalysed propylene-ethylene random copolymer (RACO) with a thickness in the range of from 1.0 to 1000 μm and C) subjecting one or more surface(s) of said article to a treatment that increases the surface tension, to yield a polypropylene based article having improved surface tension retention, wherein the surface tension increasing treatment of step C) is a chemical treatment, a Corona-treatment or a flame-treatment, and wherein the metallocene-catalysed propylene-ethylene random copolymer (RACO) is the sole polymer used for forming the article. wherein the surface tension increasing treatment of step C) is a chemical treatment, a Corona-treatment or a flame-treatment, and wherein the metallocene-catalysed propylene-ethylene random copolymer (RACO) is the sole polymer used for forming the article.