multilayer thermoplastic films and methods for the manufacture of polyurethanes

摘要

Multilayer films comprise: (A) at least one outer layer essentially comprising aliphatic thermoplastic polyurethane ; and (B) at least one outer layer essentially comprising aromatic thermoplastic polyurethane. Layers (A) and (B) are thermally bonded to each other so that delamination can not take place without at least one of the layers being damaged. The preparation of these films by (blow-film) coextrusion is also claimed. Preferably the thermoplastic polyurethanes (TPU) used have a Shore-A hardness of 75-95 (85-95) according to DIN 53505 and they contain ether soft segments. At least one layer contains one or more of the following substances : anti-fogging agents or (in)organic spacers (I), lubricants or mould release agents (II), (in)organic pigments or filler (III) or stabilisers (IV). Total film thickness is 50-400 microns with layers (A) and (B) both having a thickness of 20-250 microns