TLC polyester sheets with native fibrous cellulose. Fiber length (95 %) 2–20 μm, average degree of polymerization 400–500, specific surface acc. to Blaine 15000 cm2/g; ≤ 20 ppm Fe, 6 ppm Cu, 7 ppm P; dichloromethane extract ≤ 0.25 %; residue on ignition at 850 °C ≤ 1500 ppm.