Flexible fluid tight composite sheets

A flexible, fluid-tight composite sheet comprising a textile support coated on both faces with a compsn. based on polypropylene and additives conferring specific properties on the prod., is made by a process in which the coating is applied to the support by calendering immediately following the extrusion of the coating compsn. in the form of a film. The textile support has a structure in which the threads are disposed in such a way that interstices are formed that allow the coating compsn. to penetrate down to the core of the support. The coating is applied to one face of the support by applying the extruded film of the coating compsn. while still at an elevated temp. to the support and calendering the assembly in a calender having a smooth steel roller and a rubber-covered counter roller, with the support in contact with the rubber roller and the film in contact with the smooth roller, using a calendering press. sufficient to cause penetration of the coating into the structure of the support, then a second coating layer is applied to the other side in a similar way after preheating the first coated surface but without softening it. Feuille souple, étanche aux gaz et résistant aux produits chimiques, se présentant sous la forme d'un complexe constitué par un support textile revêtu sur au moins l'une de ses deux faces d'une couche d'enduction. Elle se caractérise en ce que: - le support textile est constitué par une structure tricotée ou tissée, - l'enduit de surface est constitué par une composition de polypropylène et de caoutchouc butyl; - l'association du support textile avec son revêtement d'enduction est réalisée par calandrage.