Arrangement in connection with the press section of a web-forming machine and board or paper produced in such arrangement

Abstract

The invention relates to an arrangement in connection with the press section of a web-forming machine. The arrangement includes at least one press nip ( 10 ) for dewatering the web ( 11 ) manufactured on a web-forming machine. The arrangement also includes a smoothing press ( 12 ) including a soothing roll ( 13 ) arranged after the press nip ( 10 ). The smoothing press ( 12 ) includes smooth heat carrying means ( 14′ ) arranged as a loop around at least two guide rolls ( 15 ). The smoothing roll ( 13 ) is arranged into contact with the means ( 14′ ) between two guide rolls ( 15 ). The smoothing roll ( 13 ) and/or at least one of the guide rolls ( 15 ) is a steam heated drying cylinder or a steam heated roll modified thereof. The invention aldo relates to a board or paper produced in such arrangement.

1 . Arrangement in connection with the press section of a web-forming machine, which arrangement includes
 at least one press nip for dewatering the web manufactured on a web-forming machine, and   a smoothing press including a smoothing roll arranged after the press nip,   characterized in that the smoothing press includes smooth heat carrying means arranged as a loop around at least two guide rolls, and the smoothing roll is arranged into contact with the means between two guide rolls, and the smoothing roll and/or at least one of the guide rolls is a steam heated drying cylinder or a steam heated roll modified thereof.   
     
     
         2 . Arrangement according to  claim 1 , characterized in that the smoothing press is arranged in the direction of motion of the web when the dry content of the web is 60% or more. 
     
     
         3 . Arrangement according to  claim 1 , characterized in that the smooth heat carrying means consist of a belt made of metal. 
     
     
         4 . Arrangement according to  claim 1 , characterized in that the smoothing roll and/or at least one of the guide rolls is arranged to be heated by steam, infrared, resistive, inductive or gas-burning heating means. 
     
     
         5 . Arrangement according to  claim 1 , characterized in that all guide rolls are steam cylinders or steam heated rolls modified thereof. 
     
     
         6 . Arrangement according to  claim 1 , characterized in that the diameter of the smoothing roll and/or the guide roll is 1000-2500 mm, preferably 1300-2000 mm. 
     
     
         7 . Arrangement according to  claim 1 , characterized in that the smoothing press has a hood. 
     
     
         8 . Arrangement according to  claim 3 , characterized in that the tension of the belt is 0.3-15 kN/m, preferably 5-10 kN/m. 
     
     
         9 . Arrangement according to  claim 3 , characterized in that in connection with both smoothing roll and belt there are cleaning equipments which include high-pressure water cleaners. 
     
     
         10 . Arrangement according to  claim 1 , characterized in that the smoothing press has a linear load which is 1-150 kN/m, preferably 5-100 kN/m. 
     
     
         11 . Arrangement according to  claim 3 , characterized in that the smoothing roll has a counter roll which is arranged inside the belt arranged as a loop. 
     
     
         12 . Arrangement according to  claim 3 , characterized in that the smoothing roll and the belt form two gaps which open downwards. 
     
     
         13 . Arrangement according  claim 1 , characterized in that in connection with the smoothing press there are auxiliary heating means for heating the web and/or the smooth heat carrying means. 
     
     
         14 . Arrangement according to  claim 1 , characterized in that the arrangement is intended for dewatering and/or processing board webs, especially liquid packaging board or cup board. 
     
     
         15 . Board or paper produced in the arrangement according to  claim 1 , for use as a liquid packaging board, having an initial roughness before pre-calendering or calendering Bendtsen value below 1000 ml/min, a Scott Bond of 120-350 J/m 2 , a bending resistance index of 8-25 Nm 6 /kg 3 , a hexanal value below 600 ppb when measured within one week from the board manufacture and an EWT (lactic acid) value below 2 kg/m 2  and/or an EWT (hydrogen peroxide) value below 2 kg 2 /m 2 . 
     
     
         16 . Board or paper produced in the arrangement according to  claim 1 , for use in the manufacture of cups for holding liquids, said board having an initial roughness before pre-calendering or calendering Bendtsen value below 1000 ml/min, a bending resistance index of at least 5 Nm 6 /kg 3 , a Scott Bond value of at least 160 J/m 2 , a CD stretch to break of at least 2.5%, preferably at least 3.5%, a hexanal value below 600 ppb when measured within one week from the board manufacture, preferably below 400 ppb, and a EWT (cream coffee) value below 1.8 kg 2 /m 2 . 
     
     
         17 . Board or paper produced in the arrangement according to  claim 1 , for use as a graphical board wherein said board having an initial roughness before pre-calendering or calendering Bendtsen value below 1000 ml/min, a Scott Bond value of at least 130 J/m 2 , a hexanal value below 1000 ppb when measured within one week from the board manufacture and a brightness (ISO-UV; measured with 420 nm filter) of at least 82% for the uncoated board. 
     
     
         18 . Board or paper produced in the arrangement according to  claim 1 , for use as food service board, said board having an initial roughness before pre-calendering or calendering Bendtsen value below 1000 ml/min, a bending resistance index of at least 5 Nm 6 /kg 3 , a Scott Bond value of at least 130 J/m 2 , a CD stretch to break of at least 2.5%, preferably at least 3.5% and a hexanal value below 600 ppb when measured within one week from the board manufacture, preferably below 400 ppb.