Abstract:
A wrapper for wrapping on a roll of length L having two opposed roll ends is described. The wrapper comprises an interior layer of a length Wi and of an interior layer basis weight, adapted to be adjacent the roll when the wrapper is wrapped on the roll; an exterior layer of a length We longer than the length Wi of the interior layer forming at least one end strip of width S and of an exterior layer basis weight, adapted to be outside of the roll when the wrapper is wrapped on the roll. The interior layer basis weight is different from the exterior layer basis weight. The end strip of the exterior layer is adapted to be folded on a corresponding one of the roll ends during crimping following wrapping of the wrapper on the roll.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to protective wrappers for rolls to reduce crimping marks on roll ends. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]    Newsprint and other forms of paper are manufactured and processed as large elongated sheets or webs. As shown in  FIG. 1  (Prior Art), for storage and transport, the paper stock is wrapped around a core plug to form a cylindrical roll, a step known as winding ( FIG. 1A ). The rolls are very heavy. A typical roll may range from 25 to 72 inches in diameter and, sometimes, as large as 145 inches or more. To protect the roll from moisture, the atmosphere, and physical abrasions, the roll itself is wrapped in a protective wrapping ( FIG. 1B ) which can be moisture proof. Specialized machinery is employed to automatically apply the wrapper to the large rolls. Typically, the rolls are then stacked one on the other and stored on end. 
         [0003]    Various methods have previously been used to wrap paper rolls. One of the most successful methods has been to first wrap the roll in one or two layers of a protective wrapper ( FIG. 1B ), with the wrapper extending outwardly beyond the ends of the roll. Next, optional interior roll headers (disks formed of corrugated cardboard, chipboard, coated chipboard or laminated kraft paper) are fitted inside the wrapper against the ends of the roll ( FIG. 1C ). The wrapper is then crimped over the edges of the interior headers at the ends of the rolls using a crimping wheel or any other appropriate technique ( FIG. 1D ). If no inside roll headers are used, the wrapper is crimped directly onto the roll of paper. Crimping creates many small surfaces that are characterized by several wrapper layers in thickness: three plies per wrap turn plus three more plies for the overlapping section (see  FIG. 2 ). 
         [0004]    A set of exterior or outside roll headers (somewhat thinner disks typically formed of a kraft paper with a polymer coating on the inside surface) are then attached to the ends of the roll over the crimped edges ( FIG. 1E ). The headers and the wrapper are held in place and affixed to one another through the use of an adhesive, such as a heat sensitive adhesive (a polymer coating), on the inside surface of the exterior roll header and/or the outward face of the interior roll header. 
         [0005]    The exterior roll headers are affixed to the ends of the rolls in a typical roll wrapping machine by applying heat and/or pressure in accordance with the properties of the adhesive used. To heat-seal the roll, pressure and high temperature are necessary. This step is known to create crimping marks on the roll ends because of the wrapper crimps that absorb energy from the heat-seal platens. 
         [0006]    When the rolls are stacked on end, the crimps crush the edge of the roll and produce indentation. Damage to the paper rolls incurs financial burden to the purchaser, the manufacturer, and/or the transporter. 
         [0007]    Crimping marks are generally created during the heat sealing process, the warehousing, the stacking of the rolls and the transportation (mainly due to vibrations and roll dropping). The crimping marks creation varies according to the paper roll density which changes with winding operations and paper grade, the impact stresses due to stacking, the wrapper thickness, the number of wrapper turns, the quality of the crimper and crimp width, the winding quality with offset edge position enhancing crimping marks, the impact strength during roll handling, the stacking procedure, the amount of stacked rolls, the warehousing period, the transportation and restacking, all varying from one mill to another, the transportation mode, rail, boat and truck causing different vibration strengths, the seasonal transportation, the inside headers variations, the position of the roll in the stack (paper roll edge in contact with floor showed more deep crimping marks than those stacked because two roll edges in contact are more compressive than a roll edge in contact with concrete floor). During transportation by a lift truck, the roll is subjected to a clamp force on its sides and by friction along its width as shown in  FIG. 3 . 
         [0008]    The cushioning chipboard header is composed of multiple fiber layers. Headers manufacturers can laminate several chipboards together to obtain a thicker header for better cushioning protection. When a pressure is applied on the top of the header, mainly due to the wrapper crimps, some pressure are absorbed by the spongy chipboard and the remaining pressure is transmitted through the chipboard. This is the transmitted pressure which causes the crimping marks. 
         [0009]    By increasing chipboard thickness, the pressure absorbed by the spongy chipboard is increased and the transmitted pressure through the chipboard is reduced, providing a better roll edge protection. So far is was the only known technology used to reduce the crimping marks. 
         [0010]    Referring back to  FIG. 3 , in order to prevent tearing of the wrapper during transport, a minimum of strength is required in the wrapper. The roll will be subjected to forces such as the transverse clamping force, the Tensile Energy Absorption (TEA), etc. In general, a wrapper having a minimum composition of a layer of 100 g/m 2 +a barrier of 20 g/m 2 +a layer of 100 g/m 2  is believed to be strong enough to withstand the forces the roll is subjected to without tearing. These forces can be approximated to 1 G when in a static position, that is one times the weight of the roll and 3 G, that is three times the weight of the roll when the roll is being transported by a lift truck, for example because of the vibrations and shocks. According to the Technical Association of Pulp and Paper Industry (TAPPI), the wrapper should have a tensile CD of 10 kN/m, a Burst strength of 1000 kPa and a tearing CD of 3.5 N. 
         [0011]    The industry has therefore developed typical wrapper design which respect these recommendations. An example of a water-vapour-proof wrapper design protection is two linerboards laminated with a barrier like Polyethylene (PE). A coated linerboard with a similar barrier can also be used. Examples of such wrapper designs are indicated in Table 1 below. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Examples of typical wrapper designs. 
               
             
          
           
               
                 Design 
                 Composition (layers) 
                 Thickness range. 
               
               
                   
               
               
                 Laminated - type 1 
                 126 g/m 2  + barrier + 126 g/m 2   
                 325-475 microns 
               
               
                 Laminated - type 2 
                 161 g/m 2  + barrier + 161 g/m 2   
                 425-575 microns. 
               
               
                 Coated 
                 269 g/m 2  + barrier 
                 350-450 microns. 
               
               
                   
               
             
          
         
       
     
         [0012]    Two wrapper layers around the paper roll with a crimped section is nine wrapper plies for a thickness range of 9 times the wrapper thickness. During the stacking process, the wrapper can be compressed up to 25% as measured on a crimp sample after a long stacking strength (pressure and time). 
         [0013]    Also, the wrapper thickness reduction is limited by the minimal wrapper strength needed to wrap a paper roll. For that reason, the reduction of the wrapper thickness is a limited technique to reduce the crimping marks. The stresses involved during the roll transportation (lift, truck, conveyor, etc.) limit the wrapper thickness decreasing since the tearing strength in both the machine direction (MD) and the cross-direction (CD), the tensile strength, the tearing strength, the bursting strength, the TEA and the stiffness are all critical physical properties needed to ensure integrity of the rolls. 
       BRIEF SUMMARY OF THE INVENTION 
       [0014]    It is therefore an aim of the present invention to address the above mentioned issues. 
         [0015]    An aspect of the invention provides a wrapper for wrapping on a roll of length L having two opposed roll ends. The wrapper comprises an interior layer of a length Wi and of an interior layer basis weight, adapted to be adjacent the roll when the wrapper is wrapped on the roll; an exterior layer of a length We longer than the length Wi of the interior layer forming at least one end strip of width S and of an exterior layer basis weight, adapted to be outside of the roll when the wrapper is wrapped on the roll. The interior layer basis weight is different from the exterior layer basis weight. The end strip of the exterior layer is adapted to be folded on a corresponding one of the roll ends during crimping following wrapping of the wrapper on the roll. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  (Prior Art) comprises  FIG. 1A  to  FIG. 1E , wherein  FIG. 1A  shows a winding step,  FIG. 1B  shows a wrapping step,  FIG. 1C  shows an optional inside headers introduction step,  FIG. 1D  shows a crimping step and  FIG. 1E  shows a heat sealing step with exterior headers; 
           [0017]      FIG. 2  shows a crimped wrapper on a paper roll with end headers with areas where there are three plies of wrapper and more; 
           [0018]      FIG. 3  shows the forces affecting the roll during transport by a lift truck; 
           [0019]      FIG. 4  is a perspective view of a paper roll being wrapped in accordance with an embodiment of the invention; 
           [0020]      FIG. 5  is a perspective view, fragmented, of a roll end of the paper roll shown in  FIG. 4 ; 
           [0021]      FIG. 6  is a top plan view, fragmented, of a roll end of the paper roll wrapped in the wrapper shown in  FIG. 4 ; 
           [0022]      FIG. 7  is a perspective view of a header mounting apparatus showing the positioning of exterior roll headers; 
           [0023]      FIG. 8  is a side elevation view of the header mounting apparatus shown in  FIG. 7  showing the roll being sandwiched between two exterior roll headers; 
           [0024]      FIG. 9  is a perspective view of the paper roll wrapped in the wrapper of  FIG. 4 , wherein interior roll headers are juxtaposed to the roll ends; 
           [0025]      FIG. 10  is a top plan view of the paper roll being wrapped with a wrapper having waved edges in accordance with an embodiment of the invention; and 
           [0026]      FIG. 11  is a graph representing the average depth of the crimping marks, in mm, versus the inside header thickness in μm, for a standard wrapper of the type where two layers of 126 g/m 2  are crimped (with diamonds), an asymmetrical wrapper in which the layer crimped is 161 g/m 2  (with triangles), an asymmetrical wrapper in which the layer crimped is 126 g/m 2  (with squares) and an asymmetrical wrapper in which the layer crimped is 90 g/m 2  (with crosses). 
       
    
    
       [0027]    It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
       DETAILED DESCRIPTION 
       [0028]    Referring now to the drawings and, more particularly, to  FIGS. 4 and 5 , there is shown a conventional paper roll  20  having a longitudinal roll axis  22 , a pair of longitudinally spaced-apart roll ends  24 , and an outer roll surface  26  extending between the roll ends  24  and radially spaced along the longitudinal roll axis  22 . The roll  20  is characterized by a length L 1  along the longitudinal roll axis  22 . 
         [0029]    The roll  20  is wrapped with a protective wrapper  30  having a width W 1 , longer than the length L 1 , in a manner such that longitudinal edge strips  32   a ,  32   b  of the wrapper  30  extend outwardly beyond the roll ends  24 . The edge strips  32   a ,  32   b  of the wrapper  30  typically extend between three to ten inches and, preferably, between four to nine inches, beyond the roll ends  24  but they can be wider or narrower. 
         [0030]    The edge strips  32   a ,  32   b  are crimped using a crimping wheel which hammers the edge strips  32   a ,  32   b  onto the ends  24  of the roll  20 . It will appreciated that any other suitable technique can be used to crimp the extending edge strips  32   a ,  32   b . Each of the edge strips  32   a ,  32   b  of the wrapper  30  overlaps onto itself on the roll ends  24  during the crimping procedure. As the edge strips  32   a ,  32   b  are crimped over the roll ends  24 , ridges  36  are produced and part of the wrapper  30  overlaps onto itself forming overlapped areas  38  ( FIGS. 5 and 6 ). 
         [0031]    An exterior roll header  42  ( FIGS. 7 and 8 ) is then secured to each of the roll ends  24  over the crimped edge strips  32   a ,  32   b  to complete the protection of the roll  20 . 
         [0032]    Referring now to  FIG. 9 , it will be seen another embodiment wherein interior roll headers are used. The roll  20  is wrapped into the wrapper  30 . Either before or after the wrapper  30  has been applied to the roll  20 , interior roll headers  34  (only one is shown) have been juxtaposed to the roll ends  24 . The edge strips  32   a ,  32   b  extend beyond the interior roll headers  34 . The extending edge strips  32   a ,  32   b  are crimped over the interior roll headers  34  ( FIG. 7 ). 
         [0033]    The roll headers  34 ,  42  are disks formed of corrugated cardboard, chipboard, or laminated kraft paper, for example. The roll headers  34 ,  42  can have adhesive properties on a face. For example they can be coated with a heat sensitive adhesive such as polyethylene. For the interior roll header  34 , the adhesive is on the face opposite to the face in contact with the roll  20 , i.e. the face in contact with the crimped edge strips  32 . For the exterior roll header  42 , the adhesive is on the face in contact with the crimped edge strips  32 . Therefore, when activated, if necessary, the adhesive bonds the roll headers  34 ,  42  to the crimped edge strips  32   a ,  32   b , as it will be described in more details below. 
         [0034]    Referring back to  FIG. 4 , the wrapper  30  comprises at least two layers. It will be referred to as an asymmetrical wrapper. The interior surface of the wrapper  30  which is in contact with the roll  20  is provided by an interior layer having an interior layer basis weight, The exterior surface of the wrapper  30  which is exposed to the surrounding conditions is provided by an exterior layer having an exterior layer basis weight. The interior layer basis weight and the exterior layer basis weight are different. Furthermore, only the exterior layer has edge strips  32 A and  32 B and has a width of W 1 . The interior layer has a width W 2  substantially equal to the length L 1  of the roll. The width of the strips  32 A and  32 B is S=(W 1 −W 2 )/2 in the case where both strips have the same width. The interior layer is positioned and affixed to the exterior layer in such a manner that it creates at least one strip, such as strips  32 A and  32 B on the exterior layer. The strips  32 A and/or  32 B are crimped and therefore, only the exterior layer of the wrapper is crimped. This ensures that the length of the roll is protected by both layers of the wrapper while reducing crimping marks since only one layer, the exterior layer, is crimped. 
         [0035]    If the basis weight of the interior layer is greater than the basis weight of the exterior layer and only the exterior layer is crimped, the crimping marks will be induced by the layer with the smallest thickness and therefore will be reduced when compared to a standard design wrapper where both layers of identical thickness are crimped. It should be noted, however, that even if the basis weight of the interior layer is smaller than the basis weight of the exterior layer and only the exterior layer is crimped, the crimping marks will still be reduced when compared to a standard design wrapper where both layers of identical thickness are crimped because only one layer of the wrapper is crimped. 
         [0036]    In some cases, the interior layer of a width W 2  will be slightly larger than the width of the roll L 1  and the interior layer will therefore be slightly crimped when the exterior layer is crimped. This will protect the edges of the roll, will not create unacceptable damages to the roll and will still reduce the crimp marks with respect to standard wrappers. 
         [0037]    A third layer, with or without moisture barrier properties, can be laminated in between the interior and exterior layers of the wrapper. The third layer may have a width of W 1  or W 2  or any width in between W 1  and W 2  and will therefore be completely crimped with the exterior layer, will not be crimped at all or will be partially crimped, respectively. 
         [0038]    Referring back to Table 1, examples of typical wrapper designs include two or three layers of materials with a thickness range from 325 to 575 microns. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Examples of typical wrapper designs. 
               
             
          
           
               
                 Design 
                 Composition (layers) 
                 Thickness range. 
               
               
                   
               
               
                 Laminated - type 1 
                 126 g/m 2  + barrier + 126 g/m 2   
                 325-475 microns 
               
               
                 Laminated - type 2 
                 161 g/m 2  + barrier + 161 g/m 2   
                 425-575 microns. 
               
               
                 Coated 
                 269 g/m 2  + barrier 
                 350-450 microns. 
               
               
                   
               
             
          
         
       
     
         [0039]    These standard wrapper designs follow the recommendations of the TAPPI. However, a single layer of 126 g/m 2  does not follow these recommendations since it has a tensile CD force of 4 to 7 kN/m, a Burst force of 450−650 kPa and a Tear CD force of 1.8-2.2 N. However, if it is crimped and sealed on a header (having a composition of 200 g/m 2 , for example), the single layer of 126 g/m 2  becomes laminated with the header and therefore stronger, yielding a tensile CD force of 15-17 kN/m, a Burst force of 1400-1650 kPa and a Tear CD force of 6.8-7.9 N. 
         [0040]    An asymmetrical wrapper design with a total composition of about 252 g/m 2  would therefore yield the same acceptable protection for the length of the roll. Similarly, other compositions could be designed to yield a total of about 269 or 322 g/m 2 . Such an asymmetrical wrapper design could be as follows. 
         [0041]    The laminated asymmetrical wrapper of example 3 has a composition of 161 g/m 2 +barrier+90 g/m 2 , wherein 161 g/m 2 +barrier is the crimping zone thickness. The laminated asymmetrical wrapper of example 4 has a composition of 90 g/m 2 +barrier+161 g/m 2 , wherein 90 g/m 2 +barrier is the crimping zone thickness. In some applications, the fact that the crimping zone thickness will be composed of the 90 g/m 2 +barrier layers will be sufficient to yield the appropriate strength for the application, In other applications, a higher thickness for the crimping zone will be required and then the crimping zone thickness composed of the 161 g/m 2 +barrier layers can be used. Other combinations of thicknesses of layers can also be used as will be readily apparent to one skilled in the art and examples 3 and 4 are solely exemplary. 
         [0042]    Table 2 below shows examples of the wrapper thickness ranges, crimp thickness ranges (which are 3 times the wrapper thickness range) and crimp section thicknesses when the wrapper is compressed by a maximum of 25% in thickness and, for the new designs, the edge thickness with its compressed thickness ranges. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Thickness ranges for each example design. 
               
             
          
           
               
                   
                   
                   
                   
                 Crimp 
                 Crimped edge 
               
               
                   
                   
                   
                 Crimp 
                 thickness 
                 thickness 
               
               
                   
                 Composition 
                 Wrapper 
                 thickness 
                 compressed 
                 (compressed) 
               
               
                 Design 
                 (layers) 
                 thickness range 
                 range 
                 at 25% 
                 ranges 
               
               
                   
               
               
                 Laminated - 
                 126 g/m 2  - 
                 325-475 
                  975-1425 
                 730-1070 
                   
               
               
                 type 1 
                 Barrier - 
                 microns 
                 microns 
                 microns 
               
               
                   
                 126 g/m 2   
               
               
                 Laminated - 
                 161 g/m 2  - 
                 425-550 
                 1275-1650 
                 956-1237 
               
               
                 type 2 
                 Barrier - 
                 microns 
                 microns 
                 microns 
               
               
                   
                 161 g/m 2   
               
               
                 Laminated 
                 161 g/m 2  - 
                 370-450 
                 1110-1350 
                 832-1012 
                  212-275 
               
               
                 Asymmetrical 
                 Barrier - 
                 microns 
                 microns 
                 microns 
                 microns 
               
               
                 Wrapper 
                 90 g/m 2   
                   
                   
                   
                 (159-206 
               
               
                 Example 3 
                   
                   
                   
                   
                 microns) 
               
               
                 Laminated 
                 90 g/m 2  - 
                 370-450 
                 1110-1350 
                 832-1012 
                  125-150 
               
               
                 Asymmetrical 
                 Barrier - 
                 microns 
                 microns 
                 microns 
                 microns 
               
               
                 Wrapper 
                 161 g/m 2   
                   
                   
                   
                  (94-113 
               
               
                 Example 4 
                   
                   
                   
                   
                 microns) 
               
               
                   
               
             
          
         
       
     
         [0043]    The edge strips  32   a ,  32   b  of the wrapper  30  can further have an exposed strip  46  of a material with adhesive properties on one or both faces. The adhesive strip can be provided on the wrapper  30  either prior to wrapping the roll  20  or once the roll  20  is wrapped. Reference is made to co-pending US published patent application no. 2006/0277866 for a detailed description of embodiments of this exposed strip  46  with adhesive properties. When wrapping the roll  20 , the exposed strip  46  can be located on the face of the wrapper  30  in contact with the interior roll header  34  and/or the end  24  of the paper roll  20  and/or in contact with the exterior roll header  42 , if any, i.e. the outer face of the wrapper  30 . 
         [0044]    For protecting the roll  20  from external moisture, the atmosphere, and physical abrasions, the wrapper can have moisture proof properties along its widths W 1 , W 2  or any width in between. The paper layers can be laminated with a material having moisture barrier properties such as PE, wax, an appropriate polymer or any other appropriate material. 
         [0045]    Referring now to  FIG. 107  another embodiment of the wrapper will be seen wherein the features are numbered with reference numerals in the  300  series. Contrary to the examples of  FIGS. 4 to 9 , the edges of the wrapper  330  are not straight edges, the edges  344   a ,  344   b  of the wrapper  330  are waved edges. The height of the ridges produced when the edge strips  332   a ,  332   b  are folded towards the roll ends  24  of the roll  20  with the waved edges is reduced. In the embodiment shown in  FIG. 10 , the waved edges are V-shaped grooves  358  cut into the edges  344  of the wrapper  330  and thereby forming substantially trapezoidal edges. The depth of the V-shaped grooves  358  can vary depending upon the characteristics of the wrapper  330 . The V-shaped grooves  358  cut along the edges  344  of the wrapper  330  reduce the severity of the indentation produced by the ridges from the wrapper overlapped areas  338 . In the embodiments shown, the V-shaped grooves  358  do not cut into the entire width of the edge strips  322   a ,  322   b . The groove  358  extends over a shorter portion than the edge strips  322   a ,  322   b  to provide sufficient edge protection. In another embodiment, the V-shaped grooves  358  can be replaced by U-shaped grooves (not shown) or any other groove shape provided in the edges  344  of the wrapper  330 . 
         [0046]    The roll  20  can be any type of rolled paper including coated printing paper. However, it will appreciate that the above described technique and wrapper can be applied to any rolled material that needs to be wrapped and protected from liquids and/or moisture infiltration. 
         [0047]    The wrapper can be manufactured on existing roll wrap extruders, laminators, and coater-laminators and can be applied to the roll  20  with existing roll wrapping equipments. 
         [0048]    It will appreciate that the roll  20  can be wrapped one turn or more by the wrapper depending upon the physical properties of the wrapper. 
         [0049]      FIG. 11  is a graph representing the average depth of the crimping marks, in mm, versus the inside header thickness in μm, for a standard wrapper of the type where two layers of 126 g/m 2  are crimped (type  1 ) (with diamonds), an asymmetrical wrapper in which the layer crimped is 161 g/m 2  (with triangles), an asymmetrical wrapper in which the layer crimped is 126 g/m 2  (with squares) and an asymmetrical wrapper in which the layer crimped is 90 g/m 2  (with crosses). 
       Experiment 
       [0050]    Seventeen paper rolls were wrapped with standard design wrappers and with asymmetrical wrappers. Different header thicknesses were used. Prior to wrapping the rolls, all packaging materials (heat sealable outside headers, chipboard inside headers, wrappers) were also conditioned to 23 deg.C and 50% of relative humidity. The purpose was to keep the same compressibility of the different packaging materials. The rolls were stacked in a conditioned room at 23 deg.C and 50% of relative humidity, and with the same stacking weight being applied on each paper rolls. The stacking period was 30 days. A paper roll without inside chipboard headers was wrapped and used as the reference for the standard wrapper. After the stacking period, the wrapper and the header, if any, on each paper roll was removed and, with a laser beam vernier, the crimping marks depth were accurately measured. In some areas of the roll edge, typically near the center, almost no crimping occurred and the edge has remained damage free. In areas closer to the outside perimeter of the roll edge, crimping has occurred and has created depressions in the roll edge surface. The highest point on the roll edge was determined to be at a position where no crimping occurred. Then, a comparative measurement was done between that point and the lowest point where crimping occurred and created a depression on the roll edge. That distance is the crimping marks depth measured. 
         [0051]    Table 3 below shows the average crimping marks depth obtained for the laminated standard wrapper of type  1 , with a composition of 126 g/m 2 -barrier-126 g/m 2  wherein all layers are crimped, the laminated asymmetrical wrapper of example 3, with a composition of 161 g/m 2 +barrier+90 g/m 2 , wherein 161 g/m 2 +barrier is the crimping zone thickness and the laminated asymmetrical wrapper of example 4, with a composition of 90 g/m 2 +barrier+161 g/m 2 , wherein 90 g/m 2 +barrier is the crimping zone thickness. The average (avg) and standard deviation (s.d.) (in italics) crimping marks depth, in μm, was measured to be as follows in Table 3, for each header thickness tested and for each wrapper design. 
         [0000]    
       
         
               
             
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Average and standard deviation crimping mark thickness versus header 
               
               
                 thickness for different wrapper designs. 
               
             
          
           
               
                   
                 Header thickness 
               
             
          
           
               
                   
                 No 
                 760 
                 1140 
                 1780 
                 2290 
                 2800 
                 3400 
               
               
                   
                 Header 
                 μm 
                 μm 
                 μm 
                 μm 
                 μm 
                 μm 
               
               
                   
                   
               
             
          
           
               
                 Standard 
                 avg 
                 1.403 
                 1.219 
                 1.098 
                 0.948 
                 0.746 
                 0.695 
                 0.652 
               
               
                 Type 1 
                 s.d. 
                 0.110 
                 0.148 
                 0.098 
                 0.058 
                 0.060 
                 0.047 
                 0.035 
               
               
                 Laminated 
                 avg 
                 N/A 
                 1.172 
                 0.870 
                 0.759 
                 0.666 
                 0.555 
                 0.474 
               
               
                 Assymetrical 
                 s.d. 
                 N/A 
                 0.031 
                 0.070 
                 0.056 
                 0.040 
                 0.043 
                 0.040 
               
               
                 Example 3 
               
               
                 Laminated 
                 avg 
                 N/A 
                 0.781 
                 0.519 
                 0.434 
                 0.348 
                 0.299 
                 0.252 
               
               
                 Assymetrical 
                 s.d. 
                 N/A 
                 0.108 
                 0.067 
                 0.029 
                 0.031 
                 0.025 
                 0.025 
               
               
                 Example 4 
               
               
                   
               
             
          
         
       
     
         [0052]    The embodiments of the invention described above are intended to be exemplary only. Several alternatives are possible. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.