Abstract: The invention is primarily concerned with a sandwich material (55) made of sheets based on paper. This material is substantially comprised of a sheet (42) of corrugated paper (44) forming one or several layers. An intermediate paper sheet (31) is bonded to the corrugations of the sheet 42. A film (29) of a thermoplastic compound adheres physically as the result of an extrusion to the outer side of the intermediate paper sheet (31).The process for manufacturing this material consists firstly in extruding a film (29) of thermoplastic compound on the intermediate paper sheet (31), and then in bonding the web (27) of protective layer thus obtained on the corrugations of the sheet of corrugated paper (42).The invention is remarkable in that these operations are carried out on a standard machine for manufacturing corrugated paperboard.