Method For the Production of a Paper Web, Especially Rotogravure Paper

Abstract

The invention relates to a method for producing a paper web or another fibrous web. According to said method, the fibrous web is impinged upon by pressure in the penultimate press nip and then in a last press nip of a press section. One face of the fibrous web is in contact with a smooth surface when penetrating the penultimate press nip while the other face of the fibrous web is in contact with a smooth surface the when penetrating the last press nip.

1 . A method for the production of a paper or another fibrous web, in which the fibrous web has pressure applied to it in a penultimate press nip and then in a last press nip of a press section,
 characterized in that   one side of the fibrous web, when passing through the penultimate press nip, is in contact with a smooth surface, and in that the other side of the fibrous web, when passing through the last press nip, is in contact with a smooth surface.   
     
     
         2 . The method as claimed in  claim 1 , characterized in that the smooth surface is formed by a roll shell with a smooth cover and/or by a smooth transfer belt. 
     
     
         3 . The method as claimed in  claim 2 , characterized in that the transfer belt is permeable or impermeable. 
     
     
         4 . The method as claimed in  claim 1 , characterized in that the press section comprises a three-nip press having a central roll and a free-standing press having a single nip, the third nip of the three-nip press being the penultimate press nip of the press section and the individual nip of the free-standing press being the last press nip of the press section. 
     
     
         5 . The method as claimed in  claim 4 , characterized in that the fibrous web is led together with a transfer belt through the second and third press nips formed between the central roll and the press rolls of the three-nip press. 
     
     
         6 . The method as claimed in  claim 2 , characterized in that one side of the fibrous web is led through the penultimate press nip in contact with the transfer belt and the other side of the fibrous web is led through the penultimate press nip in contact with a press felt. 
     
     
         7 . The method as claimed in  claim 2 , characterized in that one side of the fibrous web is led through the penultimate press nip in contact with the circumferential surface of a roll, in particular the central roll, and the other side of the fibrous web is led through the penultimate press nip in contact with a press felt. 
     
     
         8 . The method as claimed in  claim 1 , characterized in that one side of the fibrous web is led through the last press nip in contact with a press felt, and the other side of the fibrous web is led through the last press nip in contact with the circumferential surface of a press roll. 
     
     
         9 . The method as claimed in  claim 1 , characterized in that the penultimate press nip and/or the last press nip is formed as a shoe press nip. 
     
     
         10 . The method as claimed in  claim 1 , characterized in that the fibrous web is led through four press nips in the press section. 
     
     
         11 . The method as claimed in  claim 2 , characterized in that the fibrous web is transferred by a transfer suction roll from the transfer belt to the press felt of the last press nip. 
     
     
         12 . The method as claimed in  claim 11 , characterized in that the transfer suction roll has a rubber-covered circumferential surface and/or a hole pattern in the circumferential surface. 
     
     
         13 . The method as claimed in  claim 11 , characterized in that the penetration depth of the transfer suction roll with respect to the transfer belt and the fibrous web can be adjusted. 
     
     
         14 . The method as claimed in  claim 1 , characterized in that, in order to correct the cross-machine moisture profile of the fibrous web, a damping agent is applied selectively to the fibrous web at least once in the cross-machine direction at a moisture content of less than 50%, preferably after the press section. 
     
     
         15 . The method as claimed in  claim 1 , characterized in that, in order to correct the cross-machine moisture profile, a damping agent is applied selectively to the fibrous web at least once in the cross-machine direction in the forming section and/or in the press section. 
     
     
         16 . The method as claimed in  claim 1 , characterized in that the fibrous web is formed in a gap former, in particular a twin-wire former. 
     
     
         17 . The method as claimed in  claim 16 , characterized in that the gap former has flexible formation foils, preferably 1 to 10 formation foils, particularly preferably 3 to 5 formation foils. 
     
     
         18 . The method as claimed in  claim 17 , characterized in that the gap former is a vertical gap former. 
     
     
         19 . The method as claimed in  claim 16 , characterized in that the wrap angle of the forming roll by the two forming fabrics is in the range from 30° to 60°, preferably from 40° to 55°. 
     
     
         20 . The method as claimed in  claim 17 , characterized in that the formation foils are pressed against the sandwich, comprising the two forming fabrics with a fibrous web arranged between them, with a contact pressure in the range between 5 kPa and 30 kPa, preferably between 8 kPa and 25 kPa. 
     
     
         21 . The method as claimed in  claim 16 , characterized in that use is made of forming fabrics having a fabric thickness of less than 0.7 mm, preferably less than 0.65 mm, and having a number of fiber supporting points of more than 1400/cm 2 , preferably of more than 1500/cm 2 , particularly preferably of more than 1600/cm 2 . 
     
     
         22 . The method as claimed in  claim 1 , characterized in that, after running through the press section, the fibrous web is dried in a drying section. 
     
     
         23 . The method as claimed in  claim 22 , characterized in that, after running through the press section, the fibrous web is subjected to impingement drying. 
     
     
         24 . The method as claimed in  claim 23 , characterized in that the press section ( 4 ) merely comprises three press nips ( 14 ,  15 ,  16 ), and in that an impingement drying device ( 42 ) is arranged between press section ( 4 ) and drying section ( 5 ). 
     
     
         25 . The method as claimed in  claim 24 , characterized in that the three press nips ( 14 ,  15 ,  16 ) are formed by a three-nip press ( 13 ) having a central roll ( 21 ) and two press rolls ( 25 ,  26 ). 
     
     
         26 . The method as claimed in  claim 24 , characterized in that the first and/or the third press nip ( 14 ,  16 ) is formed as a shoe press nip. 
     
     
         27 . The method as claimed in one of  claims 24  to  26   claim 24 , characterized in that the impingement drying device ( 42 ) is constructed as a HighDryer. 
     
     
         28 . The method as claimed in  claim 24 , characterized in that at least one drying cylinder ( 43 ,  44 ) of the impingement drying device ( 42 ) is evacuated slightly. 
     
     
         29 . The method as claimed in  claim 28 , characterized in that stabilizers ( 54 ) are used for the evacuation of the drying cylinders ( 43 ,  44 ). 
     
     
         30 . The method as claimed in  claim 1 , characterized in that, following its drying in the drying section, the fibrous web is fed to a multi-nip calendering device. 
     
     
         31 . The method as claimed in  claim 30 , characterized in that the multi-nip calendering device is an online calendering device. 
     
     
         32 . The method as claimed in  claim 1 , characterized in that the moisture content of the fibrous web as it leaves the drying section is below the equilibrium moisture content under standard climatic conditions. 
     
     
         33 . The method as claimed in claimed  32 , characterized in that the fibrous web is moistened before entering the calendering device. 
     
     
         34 . The method as claimed in  claims 33 , characterized in that the fibrous web is moistened selectively in the cross-machine direction. 
     
     
         35 . The method as claimed in  claim 30 , characterized in that one of the two sides of the fibrous web in each case is brought into contact with a heated roll in a first sequence of nips, and in that the other of the two sides of the fibrous web in each case is brought into contact with a heated roll in a second sequence of nips. 
     
     
         36 . The method as claimed in  claim 35 , characterized in that, before each sequence of nips, in each case the side of the fibrous web which is brought into contact with the heated roll is moistened. 
     
     
         37 . The method as claimed in  claim 36 , characterized in that the fibrous web is preferably moistened to a moisture content of 7% to 9%, particularly preferably to a moisture content of 8%. 
     
     
         38 . The method as claimed in  claim 30 , characterized in that, before entering the calendering device, the fibrous web is moistened, preferably to a moisture content of 7% to 9%, particularly preferably to a moisture content of 8%. 
     
     
         39 . The method as claimed in  claim 38 , characterized in that, before entering the calendering device, the fibrous web is moistened on both sides. 
     
     
         40 . The method as claimed in  claim 36 , characterized in that the fibrous web is moistened by means of steam moisteners and/or nozzle moisteners. 
     
     
         41 . The method as claimed in  claim 1 , characterized in that the fibrous web produced is rotogravure paper (SC or SCA+ paper). 
     
     
         42 . The method as claimed in  claim 41 , characterized in that the rotogravure paper has a filler content of 25% or more, preferably of 30% or more.