Method for producing fiber product

Abstract

This invention concerns the production of a multilayer fiber product. According to the method, on top of a bottom layer consisting of at least one fiber layer, a second fiber layer is fitted containing filler that forms the surface layer. According to the invention, the layers are formed by multilayer web forming technology, and the surface layer filler includes cellulose or lignocellulose fibrils, on which light-scattering material particles are deposited, having a maximum proportion of the total filler weight of 85%. By means of the invention, a base paper is achieved that is suited to thin, coated paper grades, where conventionally the intrusion of the coating color into the bottom paper and through it is a problem.

1 . A method of producing a multilayer fiber product, comprising a thin base paper, having a grammage of 80 g/m 2  at the most, the method comprising fitting on top of a bottom layer consisting of at least one fiber layer ( 2 ;  4 - 6 ) a second fiber layer, which contains a filler and which forms the surface layer of the fiber product ( 1 ;  3 ),  
     characterized in that 
 the layers are formed by using multilayer technology, and  
 the filler of the surface layer ( 1 ;  3 ) consists at least partially of cellulose or lignocellulose fibrils, on which light-scattering material particles are deposited, the maximum content of which is 85% of the total weight of the filler.  
 
   
   
       2 . The method according to  claim 1 , characterized in that the slush of pulp is layered in the headbox of a paper machine in such way that filler and additives are added to the pulp used in the surface layer/layers of the multilayer product, after which the pulps are fed separated from each other to the headbox and then immediately combined before the lip of the headbox, where the jet of the pulp slush is directed to the wire.  
   
   
       3 . The method according to  claim 1 , characterized by using a filler, which comprises cellulose or lignocellulose fibrils produced from vegetable fibers by refining and screening, and having an average thickness is less than 5 μm.  
   
   
       4 . The method according to  claim 3 , characterized in that the light-scattering material particles are deposited on fibrils, which correspond to a fraction that passes a 50 mesh screen and/or whose average thickness is 0.1-10 μm with an average length of 10-1500 μm.  
   
   
       5 . The method according to  claim 1 , characterized in that the light-scattering material particles are inorganic salts that can be formed from their source materials by precipitating in an aqueous medium.  
   
   
       6 . The method according to  claim 5 , characterised in that the light scattering material particles are calcium carbonate, calcium oxalate, calcium sulphate, barium sulphate or mixtures thereof.  
   
   
       7 . The method according to  claim 1 , characterised in that the proportion of inorganic salts of the weight of the filler is 75-85% by weight.  
   
   
       8 . The method according to  claim 1 , characterised by producing a three-layer fiber product, whose non-coated grammage is 20-60 g/m 2 , the grammage of one surface layer being approximately 2-20 g/m 2 .  
   
   
       9 . The method according to  claim 1 , characterised in that the ratio of the total weight of the surface layers in relation to the weight of the middle layer (layers) weight is 20/80 to 80/20.  
   
   
       10 . The method according to  claim 1 , characterised in that the bottom layer comprises chemical cellulose pulp.  
   
   
       11 . The method according to  claim 1 , characterised in that the surface layer comprises mechanical pulp.  
   
   
       12 . The method according to  claim 1 , characterised by producing a thin, multilayer base paper, whose maximum grammage is approximately 80 g/m 2 .  
   
   
       13 . The method according to  claim 1 , characterised by producing a base paper of LWC paper, the bottom layer and the surface layer/surface layers both comprising a mixture of chemical cellulose pulp and mechanical pulp, and wherein a mechanical pulp, which is rougher than that used for forming the surface layer, optionally is being used for forming the bottom layer.  
   
   
       14 . The method according to  claim 1 , characterised in that the ratio of the total weight of the surface layers in relation to the weight of the middle layer (layers) weight is 30/70 to 70/30.  
   
   
       15 . The method according to  claim 1 , characterised in that the ratio of the total weight of the surface layers in relation to the weight of the middle layer (layers) weight is 35/65 to 65/35.