the invention relates to a white , biaxially oriented film which comprises a crystallizable thermoplastic as main componet and is characterized by further comprising at least one uv - stabilizer , at least one white pigment and at least one flame - proofing agent , which is soluble in the thermoplastic and introduced directly , during the film production , by masterbatch technology , whereby the masterbatch is pre - conditioned by gradual heating under reduced pressure and with stirring .