Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Of varying cross-sectional area or with intermittent...
Reexamination Certificate
2000-11-21
2003-12-02
Eashoo, Mark (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Of varying cross-sectional area or with intermittent...
C264S171130, C156S244150
Reexamination Certificate
active
06656403
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to touch fasteners, and specifically to composite touch fasteners having both loops and loop-engageable fastener elements extending from one side of a common substrate, to their application in products such as closure strips for reclosable bags, and to methods and apparatus for their manufacture.
There has been much development over the last thirty years in the field of hook-and-loop fasteners. Early touch fastener products of this type consisted of two mating tapes, each being knit or woven. One tape would include loops of filament woven into a base, and the other would include filaments woven to form loops and then cut to form hooks. In some cases free ends of drawn plastic filaments on the male tape would be melted to form protruding heads. This shape of fastener element is sometimes called a “mushroom”, to distinguish it from “hook”-shaped elements with re-entrant crooks.
More recently, continuous molding of fastener elements extending from a common sheet-form resin base has resulted in less expensive and thinner male tapes. Significant improvements in this area include the development of continuous fastener tape molding using fixed mold cavities (see Fischer, U.S. Pat. 4,794,028), and the ability to provide loops on the back side of the male fastener tape as the fastener tape substrate and elements are being formed (see Kennedy et al., U.S. Pat. 5,260,015), thus creating a composite fastener tape capable of fastening to itself. Further improvements have reduced the size of the fastener elements moldable by such techniques, to heights of 0.015 inch or less, which provide a very smooth touch when arranged in dense arrays.
As molded fastener tape has been improved to be more flexible and less expensive, it has found application in disposable garments, such as diapers. Further improvements are desirable to extend the applicability of molded touch fastener products to other uses.
One such use that is discussed in more detail below is as a closure for reclosable bags and other such packaging. Other types of repeated use closures for such bags include, for instance, the rib-and-groove type of closure such as is marketed under the name ZIPLOCK.
SUMMARY OF THE INVENTION
The invention features, in several of its aspects, a composite touch fastener product having both a band of loops and a band of hooks extending from a single face of a common, sheet-form substrate. Among other applications, this product can be included at the opening of a bag to function as a repeated use closure.
According to one aspect of the invention, an elongated closure strip includes a sheet-form resin substrate having a front face, a loop strip carried on the front face of the substrate, and an array of loop-engageable fastener elements integrally molded with resin of the front face of the substrate. The Loop strip comprises a non-woven web of fibers forming a discrete band of hook-engageable loops extending along the length of the closure strip, and the array of fastener elements forms a discrete band of fastener elements extending longitudinally along the length of the closure strip and spaced apart from the band of loops.
The closure strip is preferably constructed to be folded along a region between the bands of fastener elements and loops to place these bands in releasable engagement.
In some embodiments, the loop strip comprises a non-woven web of entangled fibers forming the loops and having a basis weight of less than about 4 ounces per square yard (preferably, less than about 2 ounces per square yard). In some cases, the non-woven web comprises a needled web in a stretched condition.
In some embodiments, fibers of the loop strip are affixed to the substrate across the width of the loop strip, such as by being encapsulated by resin of the substrate.
By “width” of the loop strip, we mean the entire transverse dimension of the preformed strip, as measured between the outermost edges of the preformed strip before it is attached to the substrate.
In many cases, the loop strip has a fiber density which is substantially constant across its width, yet the loop strip has discrete regions which are more encapsulated by resin than other regions of the loop strip. These discrete, more encapsulated regions may be spaced apart longitudinally along the loop strip, extend lengthwise along the loop strip and be spaced apart widthwise, or be arranged in a checkerboard pattern, for instance.
When we refer to regions of the loop strip as being more “encapsulated” than other regions, we mean that the fibers of the more encapsulated regions are generally more thoroughly embedded in the resin of the substrate than the fibers of other regions. Generally, this will involve a deeper penetration of the substrate resin into the loop strip.
In some embodiments, longitudinal edge regions of the loop strip are affixed to the substrate, while a center region (between the edge regions) is substantially loose from the substrate. The center region of the loop strip may advantageously define a gentle arc extending away from the substrate in some of these embodiments.
In some configurations, a barrier layer (of a different material than the substrate) is included between the substrate and the loop strip. This barrier layer may be of paper or a polymer resin, for example.
In some cases the loop strip has at least one edge which is substantially loose from the substrate. This edge may be either an inner or outer edge in a finished bag, and can help to redirect peel separation forces to enhance the peel strength of the fastening.
In some closure strips, open-ended pockets are defined between an edge of the loop strip and the substrate. These pockets can also help to enhance peel strength in some cases.
In some embodiments, the edge regions of the loop strip have fibers directly encapsulated within resin of the substrate, while the closure strip also includes a binder (of a different material than the substrate) connecting fibers of the center region (between the edge regions) of the loop strip to resin of the substrate.
In some presently preferred embodiments, the substrate defines a pair of grooves extending longitudinally along the length of the closure strip between the band of loops and the band of fastener elements. These grooves are preferably lengthwise continuous and defined by molded surfaces in the front face of the substrate.
The closure strip also includes, in some cases, a longitudinal rib integrally molded with and extending from the front face of the substrate between the band of loops and the band of fastener elements. In some of these cases, the rib is disposed between the pair of grooves just described.
In some embodiments, the front face of the substrate has two longitudinal edge regions void of fastener elements and loops, for permanently adhering the substrate to the sides of a bag. These edge regions may be covered with a layer of adhesive for permanently attaching the closure strip to opposite sides of a bag, or comprise exposed resin of the substrate, for permanently welding the closure strip to opposite sides of a bag formed of a compatible material. These longitudinal edge regions may alternatively be disposed on the back face of the substrate.
The substrate of some embodiments of the closure strip is advantageously formed of polyethylene, such as for welding the substrate to polyethylene bag material.
Some embodiments of the closure strip also include an adhesive strip carried on the front face of the substrate between the band of fastener elements and the band of loops. The adhesive strip has an exposed surface arranged to contact the front face of the closure strip when the closure strip is folded to engage the loops with the fastener elements, to retain the closure strip in a folded state.
Alternatively, some embodiments have a first adhesive strip carried on the front face of the substrate between the band of fastener elements and the pair of grooves, and a second adhesive strip carried on the front face of the substrate between the band of loops
Clune William
Shepard William H.
Eashoo Mark
Velcro Industries B.V.
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