Multi=layer plastic film and manufacturing process in which two layers are co-extruded and connected to each other

摘要

A multi-layer film comprises a rubbery elastic first layer (1) of a thermoplastic material and a second thermoplastic layer (2) attached to the first at spaced connecting points (4). Compared to the first layer (1) the extensibility of the second layer (2) is low and in the non-stretched state consists of a smooth material which after a common extension with the rubber elastic layer and subsequent recovery of the latter remains at the extended length to form bulges between the connecting points (4). Both layers (1,2) are coextruded and are incompatible in the sense that they only have slight adhesion to each other after extrusion, permanent connection between the layers (1,2) being achieved by coupling agent application at individual points or along strips (4) between the layers. In a process for manufacturing the multi-layer film the layers are coextruded in incompatible thermoplastic materials, with point or strip application of coupling agent between the layers and at a distance from each other. After common extension with the elastic first layer (1) and subsequent recovery the second layer (2) retains an extension of at least 120%, which due to recovery of the first layer(1) to an extension of /}10% creates bulges in the second layer(2) between the connecting points (4). The breaking elongation of the first layer (1) is >= 150%, preferably >= 250%.