. . "A polymer layer containing these polymers has a recommended weight in the range 7-20 g/m.sup.2.These polymers can be used as such in the chargeable layer, or they can be doped in another polymer, such as a polyolefin contained in an upper shield layer.Polymers suitable for the outermost coating layer acting as a mechanical shield and a printing surface comprise, besides the low-density polyethene" . .