Patent ID: 8070900
Filing Date: 2011-12-06
Classification: B29C,B29K,B29L,Y10T

Abstract:
1. A process for the production of a blister sheet which comprises the following steps: a) extrusion of a bottom film, a central film, a top film starting from the corresponding granule; b) thermoforming of the central film to form a thermoformed film having a top and a bottom surface while maintaining the central film at a temperature ranging from the vicat temperature to a temperature 5° lower than the vicat temperature; c) calibration and partially cooling of the bottom and top films to crystallize the bottom and top films so that they are non-deformable in the absence of mechanical action, thereafter heating at least one side of the bottom and top films, and thereafter coupling the bottom and top films to the top and bottom surface of said thermoformed film with pressing wherein said coupling of the top and bottom films with the central thermoformed film is simultaneous wherein each of the film components is a multilayer structure of at least three layers and each of the film components is a multilayer structure produced in coextrusion with three layers, wherein the coextruded three-layer structure consists of an internal polypropylene homopolymer layer and two outer polypropylene copolymer layers.