Plastic liner bag with mouth retainer means

Abstract

A pleated neckdown bag for lining a receptacle is disclosed wherein the bag is made of a flexible plastic film. The disclosed bag has one or more pleat portions (18) fixed at points around the mouth portion (26) of the bag to reduce the circumference of the mouth portion relative to the circumference of the body portion (14). The reduced circumference mouth portion of the neckdown bag can be fitted over a supporting receptacle. The top portion (12) of the bag is thereby more securely held to the support, and the mouth portion is more securely held in an open state, since the narrowed mouth portion of the bag can better engage a support such as the rim of a waste bin. Bag embodiments having flat and flat rectangular constructions, convenient for manufacture, storage, shipping, and dispensing, are also disclosed. Also disclosed is a tabbed neckdown bag embodiment with a tab (52) modifying means to advantageously modify stress and strain at and near the conjunction of a seam and mouth portion of a neckdown bag. The tab is intended to reduce or eliminate the possibility of tearing of the bag at or near a seam in the neighborhood of the tab. The tab projects from a tab base (58), defined between first (54) and second (56) reentrant arcuate portions of a mouth edge (36), and a top seam portion (20) of the bag extends across the tab base and into the tab. Also disclosed is a tab embodiment, usable in a pleated neckdown bag having a flat construction, where inclusion of the tab does not limit certain advantages pertaining to a flat bag construction.

Description

[0001] This application is a continuation of U.S. Ser. No. 09 / 366,679, filed Aug. 4, 1999.[0002] 1. Field of the Invention[0003] The invention relates to generally tubular bags, or liners, made of flexible plastic film and used to line a rigid or semi-rigid receptacle such as a waste bin or other collection receptacle. More particularly, the invention relates to a bag having one or more pleats fixed at points around the mouth portion of the bag to reduce the circumference of the mouth of the bag relative to that of the body portion of the bag. When the bag is placed into a supporting receptacle, such as a waste or recycling bin for example, the reduced mouth portion of the pleated bag may be fitted onto the rim of the receptacle and the top portion of the bag will then more securely engage with the receptacle. The bag is thereby more securely held to the support and the mouth portion of the bag is more securely held in an open state. The invention further relates, in certain embodim...

AI Technical Summary

Benefits of technology

[0016] In accordance with the present invention a pleated neckdown bag made of a flexible plastic film, and for lining a receptacle, is disclosed wherein the neckdown feature of the bag is constructed by pleating the bag inwardly at one or more points around the mouth portion. Two side, or flank, portions of a given pleat portion of the bag are joined together along the top portion of the bag. The joining means interconnecting the flanks of a pleat will generally form a seam, or seam portion, partway across the top portion of the bag, the seam perhaps comprising a heat or fused seal, adhesive bond, or a joinder. The inwardmost portion or end of such a seam portion, that is the end nearest or adjacent the mouth of the bag, effectively restricts the mouth portion so that the circumference of the mouth portion is substantially less than that of the body portion of the bag. The neckdown bag can be expanded and the reduced circumference mouth portion fitted over a supporting receptacle. The top portion of the bag is thereby more securely held to the support, and the mouth portion is more securely held in an open state, since the narrowed mouth portion of the bag can better engage a support such as the rim of a waste or other collection receptacle. Bag embodiments are disclosed having flat constructions and flat rectangular constructions, both convenient for manufacture, packaging, storage, and dispensing.

[0017] Certain disclosed embodiments of the present invention provide for a "tab", that is, a "finlike" extension of a portion of a bag adjacent an edge defining a mouth edge of the bag. Each tab is arranged about the mouth portion of the bag so that the tab projects from a tab base, defined between first and second reentrant arcuate portions of a mouth edge, and a top seam portion of the bag extends across the tab base and into the tab. Such a tab will advantageously modify the stress and strain in the bag at and near the tab so as to reduce the possibility of tearing the seam or mouth portion of the bag in the neighborhood of the tab. A particular tab embodiment is also disclosed that offers tear protection while allowing the bag to retain a typical "flat" construction.

[0019] It is the object of the present invention to provide a pleated neckdown bag for lining a receptacle, wherein the bag is made of a flexible plastic film. The narrowed, or neckdown, mouth portion of such a bag may be fitted onto the rim of a rigid or semi-rigid supporting receptacle, such as a waste bin, so the top portion of the bag more reliably engages with the supporting receptacle, and the mouth portion of the bag is more securely held in a generally open state. In certain embodiments, the invention has the further object to construct and employ a pleated neckdown bag made of a typical low cost plastic bag film, such as a polyethylene based film. It is the further object, in certain embodiments of the invention, to provide a generally flat pleated bag construction that is relatively straightforward both to manufacture, and to package, especially by automated or semi-automated means, and lends itself to more convenient storage and dispensing. It is the further object of the invention, in certain embodiments thereof, to provide a pleated neckdown bag construction having one or more tabs for advantageously modifying stress and strain at and near the conjunction of a seam and mouth portion of a bag. Each tab is intended to reduce or eliminate the chance of tearing of the bag when in use, at or near the mouth and seam portions, where such tearing might be detrimental to the retaining function of the bag. Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.

Problems solved by technology

Owing to the flexible, pliant nature of a plastic film, a plastic bag is generally not self supporting, nor is the mouth portion of a bag able to reliably remain in an open state on its own.

Unfortunately, this method of supporting the bag and bag mouth is often attended with a tendency for the top portion of the bag to slide or fall off, or otherwise disengage from, the supporting structure.

However, in this case the top portion of the bag, when folded over a rim or lip of the supporting structure, may yield a loose fit at best, and therefore offer little additional support for the bag.

It is further asserted that the elasticity of the typical liner bag is relatively low and the bags will often tear when pulled too hard.

These perceived drawbacks of a typical liner bag film force the design of the bag disclosed to require an "elastic band" or head member to be permanently attached to the bag body.

It is apparent that such a bag design, while functional, is complicated by having the liner made of two distinct members, the relatively stiff bag body, and the elastic band or head member.

The two members are required to be intimately attached along a common edge, leading to a necessary complexity in the bag structure and in the manufacture of such a liner bag.

Disadvantages are apparent in Inazeki et al in that the bag supporting function relies strictly on the principle that the bag body material is "non-elastic", or inelastic, and thereby can bear no stretching either on installation of the bag to its support, or while the bag is being supported.

The need for the hoop support greatly limits the types of support receptacles that can be used with the bag and increases the complexity and cost of such a system.

The method disclosed is limited to materials that will neck-down when cold stretched.

Another drawback to this method is that there is a limit to the degree of reduction of bag diameter that can be achieved with the method disclosed and the method requires highly specialized equipment to introduce the necking-down phenomena to the bag.

The knot method of forming a neckdown bag does not lend itself to mass production or convenient bulk packaging, and can become cumbersome for large liners or liners having heavy walls.

Moreover, this method can be difficult or impossible to implement for someone unable to effect the knot due to lack of dexterity possibly due to physical impairment such as arthritis or a Repetitive Stress Injury.

Further, one involved in the cleaning or janitorial service industry using this method will be forced to tie knots many times a day possibly leading eventually to a Repetitive Stress Injury as a result of the excessive repetition of tying many knots over long periods.

The tying off method results in one or more unsightly "pigtails", left on the outer rim of the support by the existence of the knot or knots.

Finally, the use of a knot in a neckdown bag may require an excess of film material to be used in order to make up the knot, and thereby result in a liner having an effectively shorter length which may then not fit the support or bin, or may require a longer liner and therefore a wastage of bag film material.

When a pleated neckdown bag is initially fitted onto a supporting receptacle, the bag film at and near the mouth portion of the bag is susceptible to tearing, especially at any seam restricting the mouth portion.

Because the plastic film at and near the mouth portion of the neckdown bag continues supporting the bag and bag mouth during the service life of the bag, the film is apt to tear when the bag is in service as well.

This is because the forces applied to the bag mouth on installation, and the possibility of somewhat lessened film strength in or near a seam, results in a relatively increased possibility of tearing the plastic film at or near this location more so than at other points around the mouth.

A tear, once initiated, may then continue to propagate preferentially along the seam and may then impair the neckdown feature and, hence, reduce or eliminate the advantages obtained thereby.

The method of providing a second weakened area, as in U.S. Pat. No. 3,485,437, while it can control a tear by redirecting it away from the seam, does not necessarily eliminate the occurrence of a tear.

Such a tear, even if it is redirected away from the seam, could still be detrimental to the retaining function of a neckdown bag.

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