| 摘要 |
<p>A stretched composite polyester film which has a thickness of 40-300μm, crystalline or semicrystalline, and which consists of a thick layer A having the thickness e1, mainly without filler, and of, on at least one surface of A, a thin layer B, where appropriate +B') which has a thickness e2 (where appropriate +e'2), which is likewise stretched and which has a total roughness which is greater than 0.3μm, the ratio e with /e1 being less than 5% and the percentage proportion of the scattered light, after passage through the composite film, being less than 7. The composite film is produced by means of coextrusion, with it being possible for the filler material in B to be supplied during the preparation of the polymeric, for example of a suspension, or to consist of catalyst residues, and the subsequent, customary after-treatment. The composite films have a high roughness at the same time as high transparency and can be used in the graphics field, for example for mechanically producing offset sheets.</p> |
