US Patent 8128779 Method of making multilayer polyurethane protective film

A method of making a multilayer protective film. The method comprises: (a) forming a PU layer comprising an at least partially crosslinked polyurethane, the at least partially crosslinked polyurethane comprising at least one of a polyester-based polyurethane or a polycarbonate-based polyurethane; (b) forming a TPU layer comprising a polycaprolactone-based thermoplastic polyurethane; (c) forming a PSA layer comprising a pressure sensitive adhesive; (d) bonding one major surface of the PU layer to one major surface of the TPU layer; and (e) bonding the PSA layer to an opposite major surface of the TPU layer; wherein the TPU layer is sandwiched between the PU layer and the PSA layer. The multilayer film may be used to protect painted surfaces of vehicle body parts.