Disposable fluid-handling articles are often produced on high-speed converting lines using continuous webs of fabrics, films, foams, elastomerics, etc. Many of these articles preferably include an elastomeric region or component. Typically, the elastomeric component is covered on at least one side, and preferably two sides, by a nonwoven. This combination of nonwoven and an elastomeric is referred to hereinafter as an elastomeric nonwoven laminate.
Elastomeric nonwoven laminates typically include an elastomeric bonded to a nonwoven. The elastomeric may include elastic film or elastomeric strands; however, elastomeric strands are generally preferred over elastic films since strands require less material and provide flexibility in arrangement and stretch properties. In one such laminate, a plurality of elastomeric strands is joined to a nonwoven while the plurality of strands is in a stretched condition so that when the elastomeric strands relax, the nonwoven gathers between the locations where it is bonded to the elastomeric strands forming corrugations. The resulting laminate is stretchable to the extent that the corrugations allow the elastomeric to elongate.
Elastomeric nonwoven laminates with elastomeric strands may be produced by extruding a plurality of heated filaments onto a conveyor or roller where the filaments are cooled and transferred to a nonwoven. Alternatively, the plurality of strands may be unwound from a supply roll and joined to a nonwoven. In either case, arranging the strands uniformly on the nonwoven can be difficult. The elastomeric strands are typically transferred to the nonwoven and bonded by passing the combination through a nip formed between two rolls.
When using extruded strand elastomerics, there are many situations which increase the startup time for the process, increase the amount of wasted material, or cause downtime for the process. For instance, in a typical elastomeric extrusion process, a nozzle opening that emits the molten elastomeric is larger than the actual size of the elastomeric strand. The molten strand is typically drawn such that the diameter of the elastomeric strand which ends up in the laminate structure is smaller than the size of the initial elastomeric strand emitted. During startup and the initial extrusion however, the elastomeric strands will tend to slide on the conveyor or roller. Because there is little normal force active upon the strands, the strands will tend to slide upon the conveyor or roller. Until a sufficient length of elastomeric strand has been emitted, the strand will typically continue to slide upon the conveyor or roller thereby increasing the startup time for the process.
Other problems include the transfer of the elastomeric strands to the nonwoven. Because the elastomeric strands are typically unsupported, the vibrations and speed of operation cause the strands to fall out of alignment, overlap, entangle, and bundle with neighboring strands. The unsupported strands can also break or stick to the conveyor and not transfer to the nonwoven at all which results in downtime for the process.
In addition to the transfer of the elastomeric strands, broken strands can also cause significant problems particularly if the strands are tensioned. If a strand breaks under tension, the strand will tend to snap back a significant distance towards its origination such that the alignment of the strands is disturbed thereby causing much of the resulting laminate corresponding to the snap back area to be wasted.
Consequently, it would be beneficial to provide a method and apparatus for producing an elastomeric nonwoven laminate that is capable of placing the plurality of continuous elastomeric strands in a controlled distribution on the mating nonwoven. In addition, it would be beneficial to provide an apparatus capable of reducing the amount of startup time for the threading of the elastomeric strands, capable of reducing the misalignment that strands under tension cause when they break, and capable of automatically capturing and threading elastomeric strands that fail to transfer to the nonwoven.