A protective film (I), having high impermeability against water in liquid and solid form, comprises a stretched, hard-filler containing polyolefin homo- or copolymer or polymer blend having a micropore structure that is permeable to water vapor. The protective (I), in addition to known additives, contains 0.5-10 wt.% of at least one dark pigment. An Independent claim is included for a laminated sheet material containing the protective film (I) as a functional layer.
