Method and device for producing a packaging material

Abstract

Press roll ( 10 ) for a laminating machine for producing a packaging material which comprises a carcass layer ( 42 ) consisting of paper or carton, and which carcass layer exhibits crease lines, through holes, openings or slits ( 43 ), which carcass layer exhibits, on one of its sides, a barrier layer ( 23 ), a plastic lining ( 31 ) which is arranged outside the barrier layer, and film ( 25 ) of laminant thermoplast which is arranged between the carcass layer and the barrier layer, with the said press roll ( 10 ) exhibiting a circular-cylindrical jacket surface having a facing ( 40 ) consisting of an elastic material. According to the invention, the said facing ( 40 ) comprises sections ( 44, 44 ′) in the jacket surface, which sections exhibit local deformation ability in relation to the surrounding facing ( 40, 44 ). The invention also relates to a method for producing packaging material and to packaging material which has been produced using this method.

1 . Press roll ( 10 ) for a laminating machine for producing a packaging material in the form of a web of the type which comprises a carcass layer ( 42 ) consisting of paper or carton, and which carcass layer exhibits crease lines, through holes, openings or slits ( 43 ), which carcass layer exhibits, on one of its sides, a barrier layer ( 23 ), preferably aluminium foil, a plastic lining ( 31 ) which is arranged outside the barrier layer and which comprises one or more thermoplastic materials, and a film ( 25 ) which consists of laminant thermoplast and which is arranged between the carcass layer and the barrier layer, with the said press roll ( 10 ) comprising a metal core exhibiting a circular-cylindrical jacket surface, which jacket surface exhibits a facing ( 40 ) consisting of an elastic material, 
 characterized in that the said facing ( 40 ) comprises sections ( 44 ,  44 ′) in the jacket surface, which sections exhibit local deformation ability in relation to the surrounding facing ( 40 ,  44 ).    
     
     
         2 . Press roll according to  claim 1 , characterized in that the said sections ( 44 ) are arranged in large number, with an essentially uniform distribution over the jacket surface.  
     
     
         3 . Press roll according to  claim 1 , characterized in that the said sections ( 44 ,  44 ′) are arranged as, or in, one or more areas ( 33 ,  44 ′) which extend as cylindrical segments around the circumference of the roll ( 10 ).  
     
     
         4 . Press roll according to any one of the preceding claims, characterized in that the said sections ( 44 ) are arranged in a quantity amounting to 0.5-20 per cm, preferably 1-10 per cm, and even more preferably 3-6 per cm, in at least one extension direction in the jacket surface.  
     
     
         5 . Press roll according to any one of claims  2 - 4 , characterized in that a void is present in the spaces ( 45 ) between the said sections ( 44 ) or in that a compressible material, having a lower E module and lower damping than a material of which the said sections consist, is arranged in these spaces.  
     
     
         6 . Press roll according to  claim 5 , characterized in that an aggregate volume V se  of the sections ( 44 ) is related to an aggregate volume V sp  of the said spaces ( 45 ) between the sections such that 0.3*V sp <V se <10*V sp , preferably 0.5*V sp <V se <7*V sp , and even more preferably V sp <V se <5*V sp .  
     
     
         7 . Press roll according to  claim 6 , characterized in that a maximal height H of one of the said sections ( 44 ) is related to a distance L such that 0.2*L<H<3*L, preferably 0.3*L<H<2*L, and, even more preferably 0.5*L<H<1.5*L, where L is the shortest distance between a bottom of two spaces ( 45 ) on each respective side of the said section ( 44 ).  
     
     
         8 . Press roll according to any one of the preceding claims, characterized in that the said sections ( 44 ) are designed with a cross section which is circular, triangular, quadrangular or hexagonal, in that the said sections are designed as elevated hemispheres or pyramids, or in that the said sections are designed as extended, wave-shaped or zigzag-shaped profiles.  
     
     
         9 . Press roll according to any one of the preceding claims, characterized in that the said facing ( 40 ) also comprises through holes ( 46 ) which extend from the jacket surface and down in the core of the roll ( 10 ), the roll also comprising means for creating a negative pressure in the said core.  
     
     
         10 . Press roll according to  claim 3 , characterized in that each section consists of a section ( 44 ′) which is essentially homogeneous in a direction around the circumference of the roll ( 10 ) and in an axial direction of the jacket surface, preferably having an extension of 3-15 cm in the said axial direction.  
     
     
         11 . Press roll according to  claim 10 , characterized in that the said sections ( 44 ′) are made up of a first elastic, polymeric material exhibiting a first damping and a first E module, and in that the surrounding facing ( 40 ) is made up of a second elastic, polymeric material exhibiting a second damping and a second E module, with the said first damping and the said first E module being lower than the said second damping and the said second E module, respectively.  
     
     
         12 . Press roll according to  claim 10  or  11 , characterized in that the said sections ( 44 ′) consist of insertions in the facing ( 40 ), which insertions exhibit a thickness which constitutes 5-25%, preferably 7-20%, and even more preferably 8-15%, of an aggregate thickness of the insertions plus the facing, with the roll ( 10 ) preferably exhibiting, at the said sections ( 44 ′), a diameter which is greater than a diameter at the surrounding facing ( 40 ).  
     
     
         13 . Method for producing packaging material in the form of a web of the type which comprises a carcass layer ( 42 ) consisting of paper or carton, which carcass layer exhibits crease lines, through holes, openings or slits ( 43 ), and which carcass layer exhibits, on one of its sides, a barrier layer ( 23 ), preferably aluminium foil, a plastic lining ( 31 ) which is arranged outside the barrier layer and which comprises one or more thermoplastic materials, and a film ( 25 ) of laminant thermoplast which is arranged between the carcass layer and barrier layer, with the said barrier layer being brought, at the same time as the said carcass layer, to adhere to the said plastic lining and/or to the said film of laminant thermoplast in a press nip ( 26 ;  32 ), to which the said plastic lining and/or the said laminant thermoplast is extruded, in molten or semimolten form, and in the form of a continuous film ( 25 ;  31 ), characterized in.that the said press nip ( 26 ;  32 ) comprises an press roll ( 10 ;  28 ) in accordance with any one of the preceding claims.  
     
     
         14 . Method according to  claim 13 , characterized in that the said press nip ( 26 ;  32 ) also comprises a cooling counter roll ( 41 ;  29 ).  
     
     
         15 . Method according to either of claims  13  or  14 , characterized in that the said press roll ( 10 ;  28 ) exhibits a peripheral speed of up to 800 m/min, preferably 300-700 m/min, and even more preferably 400-700 m/min.  
     
     
         16 . Method according to any one of claims  13 - 15 , characterized in that the said press nip ( 26 ;  32 ) exhibits a line load of 20-60 N/mm, preferably 20-50 N/mm, and a press nip length of at least 20 mm, preferably 20-35 mm, and even more preferably 20-30 mm.  
     
     
         17 . Packaging material in the form of a laminate of the type which comprises a carcass layer ( 42 ) consisting of paper or carton, which carcass layer exhibits crease lines, through holes, openings or slits ( 43 ), and which carcass layer exhibits, on one of its sides, a barrier layer ( 23 ), preferably aluminium foil, a plastic lining ( 31 ) which is arranged outside the barrier layer and which comprises one or more thermoplastic materials, and a film ( 25 ) of laminant thermoplast which is arranged between the carcass layer and the barrier layer, characterized in that it is produced using the method according to any one of claims  13 - 16 .