Structure Comprising A Binder Layer Non-Delaminable With Respect to a Metallized Substrate and Peelable With Respect To A Polypropylene Substrate
November 1, 2005
A multilayer structure comprising a metal layer or a metallized-substrate layer and a binder layer has been patented. The binder layer is made of polypropylene that is extrusion coated at a rate of more than 100 meters per minute onto the metal or metallized-substrate layer. The layers are made non-delaminable by heat treating the structure to a temperature above the melting point of the binder layer. A polypropylene layer has a melting point above the melting point of the binder. The binder layer is sandwiched between the metal layer or metallized-substrate layer and the polypropylene layer, wherein the structure is peelable between binder layer and polypropylene layer. The binder layer comprises by weight: 5-30% of a copolymer based on ethylene and one or more comonomers chosen from the group consisting of carboxylic acid esters, vinyl esters and dienes; 40-93% of a stretchable polypropylene, stretchability being defined as the ability of a rod extruded at a temperature of between 190° C. and 240° C. and pulled at a pull rate of between 50 and 250 m/min. without breaking; 2-30% of an additional polypropylene functionalized by an unsaturated carboxylic acid anhydride; the MFI of the composition being between 10 and 50 g/10 min. at 230° C./2.16 kg.