Abstract:
A method of utilizing a scrim of elastic material including cutting the elastic strands within a disposable undergarment is disclosed. The method generally follows the steps of providing two webs of fabric and an elastic scrim of mesh-like design, adhering the scrim between the two webs of fabric, determining areas where elastic material is not required, compressing the non-elastic areas with a thermal compression tool, and forming a disposable undergarment.

Description:
RELATED APPLICATION  
       [0001]     This application is a continuation-in-part of co-pending application U.S. Ser. No. 10/828,095, filed 20 Apr. 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     Disposable diapers of the children&#39;s training pant type, or of the adult incontinence type, are typically equipped with elastic strands, which generally encircle the waistband area and leg-holes. These strands of elastic are typically captured with adhesive between two layers of nonwoven materials. Various methods are used to position these elastic strands so that they produce the desired effect in the desired areas.  
         [0003]     Several methods of cutting elastic strands in diaper manufacturing exist. One method of cutting the strands is to sever them ultrasonically, as described in U.S. Pat. No. 5,660,657. As taught in U.S. Pat. No. 5,707,470, an ultrasonic device can be used to sever elastic members, while the carrier webs that encapsulate the elastics are left intact.  
         [0004]     One problem associated with prior art severing lies in the tendency of the unsecured severed ends of elastic to retract to some point beyond the limits of any adhesive pattern that is used to anchor the elastic strands to their carriers. Thus, the elastic strands are not controlled or anchored near the ends of the adhesion pattern and may snap back further into the adhesive pattern than desired. This results in an incomplete elastic pattern and poor product characteristics.  
         [0005]     The problem remains of efficiently and securely placing elastic in the undergarment in such a manner that the elastic is still effective after severing the elastic. Securing elastic strands around the back and front waists, for example, in a secure and systematic manner is conducive to high speed manufacturing associated with diaper manufacturing.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention concerns diapers and disposable undergarments having layers of elastic material and methods for producing such undergarments. The elastic material comprises a scrim or mesh-style pattern. The scrim retains its shape and flexibility, even after being applied within a diaper.  
         [0007]     Generally, a web of fabric is laid down and an adhesive is placed upon the fabric. The scrim is then placed upon the fabric and a second web of fabric is placed on top of the scrim. The webs of fabric are then sealed to each other, thereby sealing the scrim between the layers of fabric.  
         [0008]     Once the fabric layers are sealed together into a single web, the single web may be folded and bonded to form a diaper. Typically a diaper is bonded using a thermal or ultrasonic method. When this occurs, the inner elastic material will be melted and severed at the point of the bond. Normally this results in potential loss of elasticity as elastic strands may come loose or snap back when severed. However, the present invention allows the elastic material to retain its shape, even after severing.  
         [0009]     The present invention also allows quicker and easier placement of the elastic material within the webs of material. Not every area within an undergarment is desired to be elastic. The present method allows the use of heat compression to remove specific areas of elastic material after being placed between the two webs of fabric. For instance, in certain applications, elastic material is generally not necessary or wanted below the waistline of a diaper wearer. The areas where the webs of fabric are to be bonded do not need elastic material present, either. By using heat that severs and melts the elastic while retaining the required elasticity, the present method allows for the possibility to form such non-elastic areas after the webs of fabric are sealed together.  
         [0010]     Thus, the present invention generally follows the steps of providing two webs of fabric and an elastic scrim, adhering the scrim between the two webs of fabric, determining areas where elastic material is not required, compressing the non-elastic areas with a thermal compression tool, and forming a diaper garment. These steps will be more evident with the following detailed description and drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1A  shows a layout of an undergarment of the prior art having elastic strands.  
         [0012]      FIG. 1B  shows an undergarment having elastic strands formed according to the prior art.  
         [0013]      FIG. 2  is a perspective view of an embodiment of an undergarment formed according to the present invention.  
         [0014]      FIG. 3  shows an embodiment of a layout having elastic strands formed according to the present invention.  
         [0015]      FIG. 4  is an exploded sectional view of the embodiment shown in  FIG. 3 .  
         [0016]      FIG. 5  is a schematic view of a process to form an undergarment according to the present invention.  
         [0017]      FIG. 6  is a perspective view of an embodiment of an undergarment formed according to the present invention.  
         [0018]      FIG. 7  shows a second embodiment of a layout formed according to the present invention.  
         [0019]      FIG. 8  shows a schematic of a step in the present invention to form non-elastic areas. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0020]     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention that may be embodied in other specific structure. While the preferred embodiment has been described, the details may be changed without departing from the invention.  
         [0021]      FIG. 1A  shows a perspective view of a prior art undergarment blank  10 . The blank  10  is of a symmetrical design having a first half  12  and a second half  14 . As shown in  FIG. 1B , the first half  12  will form a front portion  13  of an undergarment  20  and the second half  14  will form a back portion  15  of the undergarment  20 . Elastic sections  16  and  18  are located within the first half  12  and the second half  14 , respectively. The elastic sections  16  and  18  are made up of a plurality of individual elastic strands  19 . Such a design allows for the specific designated areas of the undergarment  20  to have elastic properties instead of the entire undergarment.  
         [0022]     However, when the first half  12  and the second half  14  are sealed together along edges  24  and  26 , as known in the art, the elastic strands  19  may be severed, which can cause the elastic strands  19  not to be retained within the edges  24  and  26 . Consequently, the strands  19  may become loose and snap out of place, affecting the elasticity of the undergarment  20 , possibly even causing unwanted bunching in areas. The elastic/scrim is secured between the layers of non-woven with adhesive, except in side seal areas  24  and  26 .  
         [0023]      FIG. 2  shows a diaper  164  made according to the present invention which has a patch  166  in the front of a diaper  164  where a zone of desired inelasticity  2  is provided for, whereby the elastic material is in a deactivated state in the zone  2 . For instance, it is desirable in application of graphics as shown to have a zone of inelasticity for both comfort and for ease in printing/viewing the graphics.  
         [0024]     A perspective view of a web blank  100  formed according to the present invention is shown in  FIG. 3 . The blank  100  can be of symmetrical design, having a first half  102  and a second half  104 . The blank  100  may contain an absorbent section  106 , but is not necessary for the purpose of this invention. The first half  102  and the second half  104  further contain an elastic web or scrim  108 . The scrim  108  has a mesh-like design, with both horizontal strands  110  and vertical strands  112 . The horizontal strands  110  and the vertical strands  112  are formed from the same elastic material. The perpendicular overlap of the strands  110  and  112  creates a retaining force that allows the scrim  108  to retain its shape even if some of the strands have been severed. Thus, the scrim  108  is ideal for use in a disposable undergarment making method where heat compression tools are utilized to bond and seal the undergarment.  
         [0025]      FIG. 4  shows an exploded sectional perspective view of the first half  102 . The use of the first half  102  is merely exemplary, and  FIG. 4  could represent the second half  104 , or another section of the blank  100  where the scrim  108  has been applied, as well. The scrim  108  is placed between a first layer of material  114  and a second layer of material  116 . The layers of material  114  and  116  may be laminated, absorbent, or a combination of the two. For the purpose of this invention, it is not important specifically what composes the layers of material  114  and  116 . Preferably, however, the layers  114  and  116  are made of nonwoven fabric webs. An adhesive  118  is placed upon the first layer  114 . The scrim  108  is placed upon the first layer  114 , with the scrim  108  having a predetermined tension. Any method or machine that will stretch the scrim  108  to the desired tautness will be sufficient to carry out the present invention. The second layer  116  is then compressed over the first layer  114  and the scrim  108 , thereby securing the scrim  108  between the layers  114  and  116 . The layering process normally takes process before the material is cut into the individual blanks  100  shown in  FIG. 2 . It should be noted that the adhesive  118  could also be applied to the second layer  116 . Likewise, the adhesive  118  should be interpreted broadly as any means to secure the scrim  108  between the layers  114  and  116  and to secure the layers  114  and  116  to one another.  
         [0026]     Once the scrim  108  has been compressed and adhered between the layers  114  and  116 , a continuous web of material  120  is fed through an assembly line, as the schematic representation in  FIG. 5  shows. Leg hole materials  122 , if not previously removed, are cut at a cutting station  124 , thereby removing the material  122  contained within an approximate perimeter defined by the curved pattern of leg elastics  126  (see  FIG. 1 ). The continuous web of material  120  is folded, before or after cutting out of the leg holes, longitudinally along its centerline, thereby aligning a front waist edge  128  with a back waist edge  130 . A sealing device  152  then welds regions  132 , which are to become side seams  134  of undergarments  150 , either ultrasonically or by heat.  
         [0027]     Note that the leg-holes are preferably cut out before this point, leaving only a narrow zone for welding. The weld pattern is preferably wide enough to extend into both the left side seam of one garment  150  and the right side seam of the adjacent garment  150 . The garments  150  are then separated by passing through a cut-off knife assembly  154 , which severs the web along the transverse axis of the side seam weld  132 .  
         [0028]     Scrim  108 , but preferably not elastic is severed prior to side sealing. Once the web of material  120  passes through the sealing device  152 , each individual garment  150  now has a separate scrim  108  located in the front waist  128  and the back waist  130 . To accomplish this sealing process, the sealing device  152  preferably comprises a heat compression tool  156  and an anvil  158 , which create a zone of penetrating heat that causes the elastic strands to melt and sever. The scrims are secured in place within the waists  128  and  130 . The side seams  132  are formed but without any of the elastic material located in the regions  132 . Thus, when the individual garments  150  are cut, concern of unnecessarily and improperly cutting the elastic scrims  108  is minimized. Even if the elastic strands of the scrim  108  are melted or severed past the seam weld  132  and into the front waist  128  or back waist  130 , the scrim  108  will still maintain the desired elasticity and shape of the scrim  108 .  
         [0029]      FIG. 6  shows a perspective view of the finished undergarment  150 . The scrim  108  is shown with an unbroken continuity through both the front waist  128  and the back waist  130 . The heat-sealing process noted above has formed solid seals  134  that are free of elastic material while still maintaining elasticity in the front waist  128  and the back waist  130 .  
         [0030]      FIGS. 7 and 8  show another possible embodiment of the present method. Previously, as shown in  FIG. 2 , an individual scrim  108  is applied to both the first half  102  and the second half  104  of the blank  100 . The perspective view of  FIG. 6  shows an alternative embodiment to the arrangement of  FIG. 2 . Instead of separate scrims applied to each half, one large scrim  108  is placed over the entire blank  100 . The scrim  108  would be layered similarly as described above in  FIG. 3 . However, because there is only one scrim to be aligned instead of two separate scrims, precision is not as important. Likewise, since the scrim may be provided for the process as one web of material, the additional step of cutting the scrip to be applied to each of the first and second half of the blank is no longer necessary.  
         [0031]      FIG. 8  denotes a schematic representation of a further processing of the blank  100  as portrayed in  FIG. 7 . Once the scrim  108  is adhered within the blank  100 , a second heat compression tool  160  and a second anvil  162  compress the blank  100  in a predetermined area where elastic material is not desired. As shown in  FIG. 7 , the second compression tool  160  and the second anvil  162  would melt and sever an area of the scrim  108  so that the blank  100  resembles the blank  100  of  FIG. 1  and eventually the undergarment  150  of  FIG. 5 . While a second tool  160  and anvil  162  are contemplated, it is possible to combine all the required heating and severing steps with a single tool and anvil.  
         [0032]     The description of a second tool anvil is used as an example to show the elastic material may be removed from any portion of the undergarment. For example, undergarments, especially children&#39;s diapers, are commonly designed with pictures or patterns on the front and/or rear of the diaper. Forming diapers without elastic material in these areas prevents the pictures or patterns from being distorted, as diaper has a tendency to bunch up if elastic is present in these areas. According to this invention, a second tool anvil could be used to remove the elastic material from the area of the undergarment where the picture or pattern would be located.  
         [0033]     Likewise, depending on specific designs, more than two tool/anvil arrangements may be incorporated into the process. For instance, the leg elastics  126  (see  FIG. 3 ) may be replaced with a scrim design, which may be cause for a different or modified tool/anvil combination.  
         [0034]     The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention