Method for producing a fluid-pervious fabric for imparting a pattern to a fibre web, such a fluid-pervious fabric, and such a fibre web

Abstract

A method for producing a fluid-pervious fabric ( 301 ) for imparting a pattern to a fibre web. The fabric comprises at least one polymer material with a softening temperature, and a fabric structure ( 306 ). The fabric ( 301′ ) is heated to a temperature higher than the softening temperature, wherein a forming pressure (Δp 3 ) is applied between a first surface ( 304 ) and a second surface ( 305 ) of the fabric. Fabric patterning members ( 309,309′ ) on the support contribute to a deformation of the fabric structure ( 306 ) in the Z-direction in deformation zones ( 311 ) in which the fluid permeability remains essentially unchanged. The fabric ( 301 ) is cooled down to a temperature lower than the softening temperature rendering the deformation permanent. Furthermore, the invention relates to a fluid-pervious fabric, e.g. a wire or a felt, and patterned fibre web, e.g. a paper web, a nonwoven web, or another fibre web.

1 . A method for producing a fluid-pervious fabric ( 101 ;  201 ;  301 ;  401 ) for imparting a pattern ( 502 ,  502 ′,  502 ″) to a fibre web ( 503 ), said fabric comprising at least one polymer material with a softening temperature, a first surface ( 104 :  204 ;  304 ;  404 ), a second surface ( 105 :  205 ;  305 ;  405 ) opposite said first surface, and a fabric structure ( 106 :  206 ;  306 ;  406 ) comprising a plurality of channels providing fluid permeability between said first and said second surfaces, wherein said second surface ( 105 :  205 ;  305 ;  405 ) is brought into contact with an essentially rigid support ( 107 :  207 ;  307 ) having a fabric-contacting side ( 108 :  208 ;  308 ) with first fabric patterning members ( 109 ,  109 ′:  209 ,  209 ′;  309 ,  309 ′) in a desired configuration and a backside ( 110 :  210 ;  310 ) opposite said fabric-contacting side, characterized in that the fluid-pervious fabric ( 101 ′,  201 ′;  301 ′) is heated to a temperature higher than said softening temperature, and that a forming pressure (Δp 1 ; Δp 2 ; Δp 3 ) is applied between said first surface ( 104 :  204 ;  304 ) and said second surface ( 105 ;  205 ;  305 ), so that said first fabric patterning members ( 109 ,  109 ′:  209 ,  209 ′;  309 ,  309 ′) contribute to a deformation of said fabric structure ( 106 ;  206 ;  306 ;  406 ) in the Z-direction in deformation zones ( 111 ,  111 ′,  111 ″;  211 ;  311 ;  411 ,  411 ′,  411 ″) in which said fluid permeability remains essentially unchanged, whereafter said fluid-pervious fabric ( 101 ;  201 ;  301 ;  401 ) is cooled down to a temperature lower than said softening temperature in order to render said deformation in the Z-direction permanent.  
     
     
         2 . A method according to    claim 1   , 
 characterized in that the forming pressure (Δp 1 ) is created by means of first and second press surfaces ( 108 ,  112 ) arranged in order to form a press nip, wherein said first fabric patterning members ( 109 ,  109 ′) are provided on said first press surface ( 108 ) being part of said support ( 107 ), and are cooperating with inverse, second pattering members ( 113 ,  113 ′) on said second press surface ( 112 ).    
     
     
         3 . A method according to    claim 1    or    2   , 
 characterized in that heating means are provided in at least one of said press surfaces ( 108 ,  112 ) and heat said fabric structure ( 106 ) at least in positions intended to become said deformation zones ( 111 ,  111 ′).  
 
     
     
         4 . A method according to    claim 2    or    3   , 
 characterized in that the fluid-pervious fabric is preheated before said deformation in the Z-direction.  
 
     
     
         5 . A method according to any one of claims  2 - 4 , 
 characterized in that at least one of said press surfaces ( 108 ,  112 ) is provided on a rotatable embossing roll.    
     
     
         6 . A method according to any one of claims  2 - 5 , 
 characterized in that the second fabric patterning members ( 113 ,  113 ′) are provided on a single point deforming means programmed for generating said deformation in a chosen configuration across at least one of said surfaces of said fluid-pervious fabric contacting said support.    
     
     
         7 . A method according to    claim 1   , 
 characterized in that the forming pressure is created at least partially by means controlling the pressure in a fluid provided on at least one side of a flexible and elastic, fluid-impermeable membrane, which in cooperation with said first fabric patterning members causes said deformation in the Z-direction of the fluid-pervious fabric.    
     
     
         8 . A method according to    claim 1   , 
 characterized in that also said support ( 207 ;  307 ) is fluid-pervious, wherein a fluid of a higher temperature than said softening temperature is passed through said channels of said fluid-pervious fabric ( 201 ′;  301 ′) and through said support ( 207 ;  307 ) at a flow rate (F 2 ; F 3 ) sufficient for generating said forming pressure (Δp 2 ; Δp 3 ) and causing said deformation in the Z-direction.    
     
     
         9 . A method according to    claim 8   , 
 characterized in that a flexible and elastic membrane ( 314 ) with a lower fluid permeability than said fabric structure is brought into contact with said first surface ( 304 ) of said fluid-pervious fabric ( 301 ′), and that said fluid is passed through said membrane ( 314 ), said fabric ( 301 ′) and said support ( 307 ), wherein said membrane ( 314 ) provides a contribution to said forming pressure (Δp 3 ).    
     
     
         10 . A method according to any one of claims  7 - 9 , 
 characterized in that the support comprises a heating zone in which said fluid is added for heating said fabric and creating said forming pressure.    
     
     
         11 . A method according to any one of claims  7 - 10 , 
 characterized in that the support comprises a cooling zone subsequent to said heating zone.    
     
     
         12 . A method according to any one of claims  7 - 11 , 
 characterized in that the fluid-pervious fabric is heated with heated air before said deformation in the Z-direction, and that the fluid-pervious fabric thereafter is cooled down with cooled air in order to render said deformation permanent.    
     
     
         13 . A method according to any one of claims  7 - 12 , 
 characterized in that the support is a rotatable, cylindrical roll.    
     
     
         14 . A method according to any one of claims  7 - 13 , 
 characterized in that the support comprises a sintered metallic material or a metal wire.    
     
     
         15 . A fluid-pervious fabric for imparting a pattern to a fibre web, said fabric ( 401 ) comprising at least one polymer material with a softening temperature, a first surface ( 404 ), a second surface ( 405 ) opposite said first surface, and a fabric structure ( 406 ) comprising a plurality of channels providing fluid permeability between said first and said second surface, characterized in that the fluid-pervious fabric ( 401 ) exhibits a permanent deformation of said fabric structure ( 406 ) in the Z-direction in deformation zones ( 411 ,  411 ′,  411 ″) in which said fluid permeability is essentially equal to the fluid permeability in fabric zones outside said deformation zones.  
     
     
         16 . A fluid-pervious fabric according to    claim 15   , 
 characterized in that the polymer material exhibits portions which have been softened and subsequently solidified in the deformation zones ( 411 ,  411 ′,  411 ″).    
     
     
         17 . A fluid-pervious fabric according to    claim 15    or    16   , 
 characterized in that the fluid-pervious fabric ( 401 ) exhibits said deformation in a chosen configuration across at least one of said surfaces ( 404 ,  405 ).  
 
     
     
         18 . A patterned fibre web, comprising a plurality of fibres arranged in a fibre structure ( 515 ) having a grammage and a porosity, characterized in that the fibre web ( 503 ) exhibits a deformation of said fibre structure ( 515 ) in the Z-direction in deformation zones ( 502 ,  502 ′,  502 ″), wherein the grammage and the porosity within said deformation zones are essentially equal to the grammage and the porosity outside the deformation zones.  
     
     
         19 . A patterned fibre web according to    claim 18   , 
 characterized in that the deformation zones ( 502 ,  502 ′,  502 ″) are visible as a chosen pattern across both surfaces ( 516 ,  517 ) of said fibre web ( 503 ).    
     
     
         20 . A patterned fibre web according to    claim 18    or    19   , 
 characterized in that the fibre web ( 503 ) has been wet-formed or foam-formed.  
 
     
     
         21 . A patterned fibre web according to    claim 18    or    19   , 
 characterized in that the fibre web has been air-laid.  
 
     
     
         22 . A patterned fibre web according to any one of claims  18 - 21 , 
 characterized in that the fibre web has been hydraulically apertured or entangled.    
     
     
         23 . A patterned fibre web according to any one of claims  18 - 22 , 
 characterized in that the fibre web has been through-air dried (TAD).    
     
     
         24 . A patterned fibre web according to any one of claims  18 - 23 , 
 characterized in that the pattern ( 502 ,  502 ′,  502 ″) in the fibre web ( 503 ) has been created by means of forming and/or patterning/aperturing on, and/or drying or shaping in contact with at least one fluid-pervious fabric ( 401 ) according to any one of claims  15 - 17 .