a thermoplastic polyester film including a virtually particle free polyethyleneterephthalate core layer and a skin layer comprising inorganic and organic fillers disposed on the core layer . the inorganic fillers may include aluminum oxide particles , silicon dioxide , zirconium oxide , titanium dioxide , tin oxide , calcium carbonate , barium sulfate , calcium phosphate , zeolite , hydroxy apatite , aluminum silicate and mixtures thereof . the inorganic fillers may have a particle size of from 0 . 01 μm to 0 . 60 μm . the organic filler particles may have an average particle size of less than or equal to 1 μm and may be present in an amount of less than 0 . 1 % by weight , based on the weight of the polyethyleneterephthalate . the skin layer may have a thickness of less than 7 μm .