Method for post-processing of a product, especially paper or paperboard, which has been fabricated from pulp containing lignin

Abstract

The invention refers to a method for post-processing of a product, especially paper or paperboard, which has been fabricated at least partly from pulp containing lignin, comprising the following steps: introducing the product into a product gap of a belt press having at least one belt, heating up the product within the belt press to a temperature between 160° C. and 350° C. and submitting the product within the band press to a line pressure between 30 N/mm and 200 N/mm and/or a surface pressure between 50 kN/m2 (0.5 bar) and 600 kN/m2 (6 bar), especially between 200 kN/m2 (2 bar) and 600 kN/m2 (6 bar).

1 . A method for post-processing of a product, especially paper or paperboard, which has been fabricated at least partly from pulp containing lignin, comprising the following steps: Introducing the product into a product gap of a belt press having at least one belt, heating up the product within the belt press to a temperature between 160° C. and 350° C., especially between 250° C. and 350° C., and submitting the product within the band press to a line pressure between 30 N/mm and 200 N/mm and/or a surface pressure between 50 kN/m 2  (0.5 bar) and 600 kN/m 2  (6 bar), especially between 200 kN/m 2  (2 bar) and 600 kN/m 2  (6 bar). 
     
     
         2 . The method according to  claim 1 , comprising moistening or drying the product, especially paper, in order that the product has a moisture content of 2% to 40%, 
     
     
         3 . The method according to  claim 1 , wherein the at least one belt is a steel belt or a plastic belt. 
     
     
         4 . The method according to  claim 1 , wherein the belt press is a double belt press having at least an upper belt and at least one lower belt, wherein heating up the product and submitting the product ( 28 ) to pressure takes place in the product gap between the at least one upper belt and the at least one lower belt of the double belt press. 
     
     
         5 . The method according to  claim 4 , wherein the double belt press comprises two steel belts forming at least a portion of the product gap in-between them, wherein the double belt press comprises two plastic belts forming at least a portion of the product gap in-between them or wherein the double belt press comprises a steel belt and a plastic belt forming at least a portion of the product gap in-between them. 
     
     
         6 . The method according to  claim 5 , wherein two plastic belts form at least a portion of the product gap in-between them and wherein on the back side of at least one of the plastic belts, a steel belt runs parallel to the plastic belt for at least a portion of the product gap. 
     
     
         7 . The method according to  claim 3 , wherein an upper belt of the double belt press is perforated. 
     
     
         8 . The method according to  claim 4 , wherein the double belt press comprises a first upper belt and a second upper belt, the first upper belt being arranged upstream of the second upper belt when seen in a transport direction of the double belt press in the product gap. 
     
     
         9 . The method according to  claim 1 , wherein the pressure is applied by means of at least one pressure roller, circulating rollers, at least one S-roller, at least one counter pressure roller and/or at least one counter pressure belt. 
     
     
         10 . The method according to  claim 9 , wherein the pressure is applied by means of at least one pressure roller, circulating rollers, at least one S-roller, at least one counter pressure roller and/or at least one counter pressure belt directly to the product. 
     
     
         11 . The method according to  claim 9 , wherein the at least one pressure roller, the circulating rollers, the at least one S-roller, the at least one counter pressure roller and/or the at least one counter pressure belt touches a back side of the at least one belt, the backside of the belt facing away from the product gap. 
     
     
         12 . The method according to  claim 1 , wherein the desired temperature of the product within the belt press is achieved by heating the at least one belt. 
     
     
         13 . The method according to  claim 1 , wherein the pressure is applied and again at least partly released within the belt press at least twice. 
     
     
         14 . The method according to  claim 13 , wherein the pressure is released to a value of less than 30%, especially less than 10%, of the pressure applied immediately before releasing the pressure. 
     
     
         15 . The method to  claim 1 , wherein the pulp has been generated by mechanical pulping. 
     
     
         16 . The method according to  claim 1 , wherein the product is unwound from a first coil, then the product is introduced into the belt press and after leaving the belt press the product is coiled up on a second coil. 
     
     
         17 . The method according to  claim 1 , wherein at least two layers of product arranged on top of each other are introduced into the product gap. 
     
     
         18 . The method according to  claim 1 , wherein heating of the paper to a temperature within the boundaries indicated and submitting the product to a pressure within the boundaries indicated has an effect on the lignin within the product, thereby making the product stronger and more resistant to moisture and water.