Patent ID: 6698342
Filing Date: 2004-03-02
Classification: D21G

Abstract:
A method for a multi-roll calender for control of the moisture gradient of a fibrous web, in which method an on- or off-line multi-roll calender comprising separate first and second sets of rolls is used for calendering, in which connection each set of rolls comprises rigid-shell press rolls and resilient-shell backing rolls for the press rolls, placed alternately one after the other, in which connection successive nips are situated between the press rolls and the backing rolls placed against each other, as well as a reversing or guide member guiding the run of the fibrous web, wherein, in the on- or off-line multi-roll calender comprising two sets of rolls the fibrous web is subjected to an intermediate moistening after a first set of rolls, the method comprising the steps wherein:the moisture content of the fibrous web passed from a drying process to the calendering is raised by pre-moistening immediately preceding the first set of rolls; the fibrous web is dried in the first set of rolls; after the first set of rolls, the moisture content of the fibrous web is raised by intermediate moistening; and the fibrous web is dried to a desired final moisture level in the second set of rolls.