Wallpaper and method for production thereof

Abstract

Wallpaper base containing chemical pulp, filler, chemical additives, and, as an option, groundwood pulp. Reduction of the wet expansion is achieved in that the paper has a man-made fiber content of at least 5 wt-%.

1 . Wallpaper base with reduced wet expansion containing chemical pulp, filler, chemical additives, and, optionally, groundwood pulp, characterized in that it comprises a layer ( 3 ) which contains a fraction of at least 5 wt-% of man-made fibers.  
   
   
       2 . Wallpaper base according to  claim 1 , characterized in that the fraction of man-made fibers is no more than 50 wt-%.  
   
   
       3 . Wallpaper base according to  claim 1 , characterized in that the fraction of man-made fibers is at least 10 wt-% and no more than 30 wt-%, preferably at least 15 wt-% and no more than 25 wt-%.  
   
   
       4 . Wallpaper base according to  claim 1 , characterized in that at least a part of the man-made fibers are fully-synthetic fibers.  
   
   
       5 . Wallpaper base according to  claim 4 , characterized in that at least part of the fully-synthetic fibers are polyester fibers.  
   
   
       6 . Wallpaper base according to  claim 1 , characterized in that the mean length of the man-made fibers is less than 8 mm, preferably between 3 mm and 8 mm, particularly preferably between 4 mm and 7 mm.  
   
   
       7 . Wallpaper base according to  claim 1 , characterized in that the fraction of chemical pulp is at least 10 wt-% and no more than 80 wt-%, preferably at least 20 wt-% and no more than 60 wt-%.  
   
   
       8 . Wallpaper base according to  claim 1 , characterized in that the layer ( 3 ) contains a fraction of groundwood pulp of at least 5 wt-%, preferably at least 10 wt-%, and particularly preferably at least 20 wt-%, and no more than 50 wt-%, preferably no more than 35 wt-%.  
   
   
       9 . Wallpaper base according to  claim 1 , characterized in that the chemical additives include a fraction of a binding agent.  
   
   
       10 . Wallpaper base according to  claim 1 , characterized in that the binding agent is anionic.  
   
   
       11 . Wallpaper base according to  claim 1 , characterized in that the binding agent comprises a polymer, preferably an alkylacrylate, particularly preferably a butylacrylate.  
   
   
       12 . Wallpaper base according to  claim 11 , characterized in that the polymer is a copolymer of an alkylacrylate and styrene.  
   
   
       13 . Wallpaper base according to  claim 9 , characterized in that the fraction of the binding agent is at least 0.5 wt-% and no more than 5 wt-%.  
   
   
       14 . Wallpaper base according to  claim 9  characterized in that the chemical additives include an oppositely charged precipitation-enhancing component.  
   
   
       15 . Wallpaper base according to  claim 1 , characterized in that the chemical additives include a fraction of a wet-strength agent of at least 0.5 wt-% and no more than 5 wt-%.  
   
   
       16 . Wallpaper base according to  claim 1 , characterized in that the chemical additives include a fraction of sizing agent of at least 0.5 wt-% and no more than 5 wt-%.  
   
   
       17 . Wallpaper base according to  claim 1 , characterized in that it comprises an additional wall-facing lower layer ( 2 ).  
   
   
       18 . Wallpaper base according to  claim 16 , characterized in that the lower layer ( 2 ) contains a polymer, preferably a thermally-crosslinked polymer, particularly preferably a thermally-crosslinked copolymer.  
   
   
       19 . Wallpaper base according to  claim 18 , characterized in that the polymer is a copolymer of an alkylacrylate, preferably of butylacrylate, and, in particular, of styrene.  
   
   
       20 . Wallpaper base according to  claim 17 , characterized in that the lower layer ( 2 ) contains a wax, preferably a paraffin wax.  
   
   
       21 . Wallpaper base according to  claim 20 , characterized in that the wax fraction of the lower layer is at least 5 wt-% and no more than 30 wt-%.  
   
   
       22 . Wallpaper base according to  claim 17 , characterized in that the lower layer ( 2 ) contains a wet-strength agent preferably at a fraction of less than 5 wt-%.  
   
   
       23 . Method for the manufacture of wallpaper base according to  claim 1 , in which chemical pulp, filler, chemical additives, and, as an option, groundwood pulp are guided from a blend chest via a stock cleaning unit and a headbox to a horizontal screen, characterized in that a fraction of man-made fibers of at least 5 wt-%, relative to the solids content of the headbox, is added upstream of the headbox.  
   
   
       24 . Method according to  claim 23 , characterized in that the man-made fibers are added to the blend chest in the form of the dry fibers.  
   
   
       25 . Method according to  claim 23  wherein an oppositely charged precipitation-enhancing component is added to the stock stream subsequent to the addition of the binding agent.