Patent Application
20060265867
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.
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.
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.
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.
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.
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.
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.
a is an initial, undesirable downstream travel configuration of non-loop material with exposed and flying hook ear;
b is a desirable downstream travel configuration of non-loop material coupled with the folded hook ear, non-hook material exposed;
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.
For background purposes,
The non-loop material is preferably fibrous material, so that the fibers of the non-loop material are available to entangle the hooks.
Referring now to
If this segment were to travel downstream for further diaper manufacturing processing in the initial and undesirable configuration shown in
Therefore, it is the object of the present invention to provide, as shown in
Referring now to
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.
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.
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<f<1 GHz.) Typical would be 20 kHz systems and 35 kHz systems.
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).
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.
