Method for producing a mat of cellulose fibres with a controlled level of mineral material for bitumen-impregnated roofing elements, and suitable device

Abstract

A method for continuously producing a mat of cellulose fibers intended for producing roofing elements made from bitumen-impregnated cellulose fibers, from a dilute slurry of cellulose fibers spread by a headbox on a dewatering fabric of a forming table having a predefined width, the dewatering fabric moving between an inlet of the forming table at the headbox side and an outlet of the forming table, moving the dilute slurry towards the outlet, gradually removing the liquids of the dilute through the dewatering fabric during the movement to obtain, at the outlet, the mat having a thickness of at least 2 mm, the dilute slurry having a certain level of pre-existing mineral materials. The method involves adding mineral material to the cellulose fibers by spraying a controlled quantity of aqueous solution or dispersion of mineral fillers over the width of the forming table onto the surface of the dilute slurry.