Abstract:
An apparatus and method of temporarily coupling a hook material to a fibrous non-loop material by introducing the hook material to the non-loop material and ultrasonically vibrating at least one of the materials to cause temporary engagement between the two materials.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to improvements in methods of manufacturing disposable diaper fasteners of the type which use an adhesive bearing strip of hook and loop material to retain the diaper on a body such as that of an infant or incontinent adult.  
         [0002]     One objective of diaper machinery manufacturers is to provide for applying fastener strips to a diaper web at high speed, using the least amount of material, and using the least complex and most reliable apparatus. Another objective is to provide fasteners that are easy to use and provide a secure attachment from one part of the diaper to another so the diaper will be retained snugly on the body.  
         [0003]     Typically, the fastener strips are cut from a roll of paper tape or similar material which has one of its surface coated with a pressure sensitive adhesive, or which uses hook and loop fasteners. Adhesive segments are transferred to a moving diaper web.  
         [0004]     Hook and loop fasteners have become more increasingly used to adhere diaper portions around the waist of a user. Hook and loop fastening systems are widely used in disposable articles such as diapers and incontinence products. Often, the hook component is not intended to engage the loop component until the consumer puts the disposable article into use. Stabilizing the hook component in a machinery process used to make a disposable article is difficult. Sometimes additional materials that have a lint or “fuzzy” surface are added to the disposable article just to provide a surface to stabilize the hook component in a temporary position during the machine process used to make the disposable article. This introduces increased machine process complexity and material costs. In other cases, the hook component is allowed to negotiate the machine process in an unstable configuration that is not conducive to high-speed processes or to consistent folding and packaging of the disposable article.  
         [0005]     Therefore, it is desirable to have a method whereby the hook component can be temporarily attached to an existing non-loop material, such as a smooth nonwoven material, to maintain stability of the hook component in the machine process.  
       SUMMARY OF THE INVENTION  
       [0006]     The present invention uses an ultrasonic bonding system in the machine process to vibrate the hook components against a relatively smooth material web that is typically ineffective at engaging hook components. The vibration of the hook components against the relatively smooth material web causes the hooks to “wiggle” their way into the gaps and between the fibers of the relatively smooth material. The entanglement of the hook components with the fibers of the relatively smooth material is sufficient to stabilize the hook material through the remainder of the machine process. The gap that would typically be used between the ultrasonic horn and the smooth anvil for actual bonding applications is increased slightly so the hook component does not fuse to the relatively smooth material.  
         [0007]     This invention uses an ultrasonic bonding system in an unusual method that does not involve actual bonding of materials together, but instead creates a loose attachment. For stability in a moving machine process, the hook component of a hook and loop fastening system may need to be temporarily fixed to a material web or to a component of a material web that is not well suited to engage the hook components. An ultrasonic bonding system is used to “wiggle” the hooks of a hook-and-loop component into a non-loop material to entangle the hooks that otherwise would not entangle with simple contact and pressure. Thus engaged, the hook component is stabilized and is reliably carried through the machine process. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a diagrammatic side view of a Prior Art process;  
         [0009]      FIG. 2   a  is an initial, undesirable downstream travel configuration of non-loop material with exposed and flying hook ear;  
         [0010]      FIG. 2   b  is a desirable downstream travel configuration of non-loop material coupled with the folded hook ear, non-hook material exposed;  
         [0011]      FIG. 3  is a schematic view of an apparatus for folding a flying hook ear, tucking the ear, and bonding the hook ear to non-loop material for downstream travel. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]     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 which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.  
         [0013]     For background purposes,  FIG. 1  is shown as a diagrammatic illustration of a prior art process for applying tabs to webs in a diaper making process. Tabs  12  are coupled to the web  10 . For purposes of the present invention, tabs  12  comprise a hook material which is often used to be secured by the end user to a loop material (not shown) on a corresponding diaper of the end user when worn. Web  10  is a composite material used in formation of diapers which is generally formed of various layers of material such as plastic back sheets, absorbent pads and nonwoven topsheets. For purposes of the present invention, web  10  comprises a non-loop material, not ordinarily associated with coupled to a hook material, which ordinarily requires loops for coupling.  
         [0014]     The non-loop material is preferably fibrous material, so that the fibers of the non-loop material are available to entangle the hooks.  
         [0015]     Referring now to  FIG. 2   a , an initial, undesirable downstream travel configuration of fibrous non-loop material  10  with exposed and flying hook ear  12  is shown. The ear  12  comprises two portions, a first portion shown of hook material and an underside  12 ′ of non-hook material. Ordinarily, the hook material is provided on the ear portion in a strip although other configurations of hook material are of course capable of being used in the present invention.  
         [0016]     If this segment were to travel downstream for further diaper manufacturing processing in the initial and undesirable configuration shown in  FIG. 2   a , and negotiate the remaining machine processes (not shown) in this unstable configuration, further high-speed processes or consistent folding and packaging of the disposable article could all be impaired.  
         [0017]     Therefore, it is the object of the present invention to provide, as shown in  FIG. 2   b , a desirable downstream travel configuration of non-loop material  10  coupled with the folded hook material of ear  12 , exposing fibrous non-hook material  12 ′ and providing for a compacted downstream negotiation and slimmer profile without flying parts.  
         [0018]     Referring now to  FIG. 3 , a schematic view of an apparatus  100  for folding the flying hook ear  12 , tucking the ear  12 , and bonding the hook ear  12  to fibrous non-loop material  10  for downstream travel is shown.  
         [0019]     The apparatus  100  for accomplishing this task first comprises a folder  20  for initially folding the ear  12  over towards the fibrous non-loop material  10 . After being folded by the folder  12 , the hook material  12  will not be bonded to the non-loop material  10 , so a funnel  30  is provided to keep this proximity between the hook material  12  and fibrous non-loop material  10  formed by the folder  30  until the temporary bonding can take place. The funnel  30  comprises a top and bottom portion for holding the two portions  12  and  10  in proximity.  
         [0020]     Next, the traveling combination of the hook material  12  and fibrous non-loop material  10  encounters a horn  50  which is ultrasonically vibrated by an amplifier stack  40 . The horn ultrasonically vibrates the combination of the hook material  12  and fibrous non-loop material  10  against anvil  60 . The vibration of the hook  10  components against the relatively smooth fibrous non-loop material  10  web causes the hooks to “wiggle” their way into the gaps and between the fibers of the relatively smooth material. The entanglement of the hook components  12  with the fibers of the relatively smooth material  10  is sufficient to stabilize the hook material  12  through the remainder of the machine process. In a best mode, a gap that is typical for actual bonding applications between ultrasonic horn  50  and the smooth anvil  60  is increased slightly so the hook component  12  does not fuse to the relatively smooth material  10 .  
         [0021]     A preferred frequency of vibration in ultrasonic bonding units, such as that identified at amplifier stack  40  and horn  50  is in the ultrasound range (20 kHz&lt;f&lt;1 GHz.) Typical would be 20 kHz systems and 35 kHz systems.  
         [0022]     After being ultrasonically wiggled by horn  50 , the desirable downstream travel configuration is provided of fibrous non-loop material  10  coupled with the folded hook material of ear  12 , exposing non-hook material  12 ′ and providing for a compacted downstream negotiation and slimmer profile without flying parts of the combination. It is noted that it is not desired to bond the materials together, but instead to create a loose attachment between the two materials, so that the end user can easily disconnect the materials and reconnect the hook material  12  with its conventional loop counterpart (not shown).  
         [0023]     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, which is defined by the claims.