Multilayer polyester film with high optical density with a total thickness of max. 60 μm two white layers and a carbon-black containing outer layer

A self-extinguishing, hydrolytically stable biaxially oriented polyester film comprising at least three layers, said film comprising a carbon-black-filled exterior outer layer and two TiO2-containing layers, wherein one of the TiO2-containing layers is a white outer layer disposed opposite the carbon-black-filled outer layer on a second TiO2-containing layer which is a base layer,

• the thickness of each of the outer layers is from 4 to 15 μm,
• the thickness of the base layer is ≧the total of the thicknesses of the outer layers and at least 50% of the film total thickness,
• the white outer layer comprises polyester and at least 15% by weight of TiO2,
• the base layer comprises polyester and at least 4% by weight of TiO2,
• the carbon-black filled outer layer comprises polyester and from 3 to 15% by weight of carbon black,
• the standard viscosity value of the film is at least 600, where all % by weight data are based on the weight of the respective layer, and
• the film comprises a flame retardant,
• wherein said flame retardant is an organophosphorus compound with phosphorus present in an amount ranging from 1500 ppm to below 3000 ppm.