Method for manufacturing paperboard comprising a bulk ply

Abstract

A method for manufacturing paperboard in a paper-making machine, the method comprising the step of:forming a bulk ply by applying a pulp suspension comprising at least 50 wt% (based on the total dry weight of the pulp suspension) of high-bulk hardwood pulp and 0.01 -10 wt% (based on the total dry weight of the pulp suspension) of a strength enhancement agent selected from the group consisting of highly refined cellulose, microfibrillated cellulose (MFC), a cationic strength additive, an anionic strength additive, or a combination thereof, from a headbox onto a moving wire to form a wet web, at least partially dewatering the wet web on the wire to obtain an at least partially dewatered web, and drying the at least partially dewatered web to obtain the bulk ply;wherein the wire is provided with a wire shaker which shakes the wire at frequency of 150 - 600 strokes per minute and a stroke length of 5-25 mm.