Patent Application
20110062192
In the field of flexible fluid reservoirs, particularly those comprised of two opposing panels of film selectively bonded together and incorporating a closable spout there between, attention has been directed to providing a secure and durable bond between the opposing panels of film and the spout. To enhance the nature of bond between the films and the spout, various approaches have been taken, including inclusion of surface features such as ribs, lands and/or grooves in the spout. While intended to address a perceived problem, such solutions were not without deficiencies. Moreover, little attention has been paid to the parameters surrounding the components, namely the spout and the film, with respect to the chemical properties thereof, and how best to optimize the same.
Turning first to issues pertaining to the physical attributes of the spout, spout rib geometries of the prior art generally produced excessive pressure at the weld interface, causing the material of the film subject to bonding with the spout to be displaced rather than bond with adjacent material on the spout rib. As this material was displaced, the remaining film at this location was considerably weakened, making it particularly subject to tearing.
In addition to the foregoing, prior art spouts often included a spout geometry that resulted in stress concentration at the spout corners (in most forms, the spout corners are considered those locations where the two generally opposing side surfaces of the spout's weld interface converge) when the reservoir was filled to near capacity. This intrinsic stress was greatly amplified when the reservoir was subjected to additional loads such as those experienced during “drop-testing”. In addition, conventional spout geometries, particularly in conjunction with stiff material selection, created high stress and abrasion of the film where it wrapped around the internal edge of the spout. This could result in premature failure of the film in this area.
As noted above, prior art spouts for flexible fluid reservoirs were not known to possess nor designed to possess melting temperatures that were matched to that of target films intended to be heat or radio frequency (RF) welded thereto. As a consequence, when such a spout and target film were subjected to such welding, desired bonding qualities were not always achieved. While one solution was to apply excess heat and/or pressure to accommodate these disparities, such a solution jeopardized material performance features, particularly in the more susceptible films. In certain instances, the melt temperature of the spout base material, such as high density polyethylene (HDPE), was 8° C. higher than the base material of the film's bonding layer, such as linear low density polyethylene (LLDPE), which resulted in a less than desirable final weld. As a consequence, flexible fluid reservoirs constructed from a film material that was welded to such a spout would experience preventable failures at this interface.
The invention is intended to provide a spout, particularly for flexible fluid reservoirs comprising opposing film panels such as the type broadly characterized as personal hydration reservoirs, which minimizes stresses and abrasion resulting from manufacture and/or use of such reservoirs as well as enhances the strength of the weld/bond between the films and the spout. The various invention embodiments minimize stresses to and abrasion of the film(s) comprising such reservoirs by exploiting certain spout geometries, and enhances the strength of the weld/bond between the films and the spout through material selection and spout surface characteristics, the details of which will be disclosed in the following paragraphs.
Each spout according to the invention comprises a generally cylindrical neck portion and a pair of opposed, generally triangular portions extending laterally there from that comprise a spout-film interface (also referred to herein as a “spout weld interface”). The neck portion includes an axis that is congruent with a longitudinal direction. Depending upon embodiments, the spout weld interface(s) may comprise one or more portions of the neck portion.
For purposes of this patent, the terms “area”, “boundary”, “part”, “portion”, “surface”, “zone”, and their synonyms, equivalents and plural forms, as may be used herein and by way of example, are intended to provide descriptive references or landmarks with respect to the article and/or process being described. These and similar or equivalent terms are not intended, nor should be inferred, to delimit or define per se elements of the referenced article, unless specifically stated as such or facially clear from the several drawings and/or the context in which the term(s) is/are used. Specifically as used herein, reference to a “weld interface” also includes the plural form and vice versa, and should not be inferred as limiting the embodiments or claimed invention to one form or the other based solely upon term selection and usage.
Certain spout embodiments of the invention comprise at least one material having a melting temperature, at least at spout weld interfaces thereof, which is closely matched to at least a portion of film-spout interfaces that that are part of a flexible fluid reservoir film (also referred to herein as “film weld interface(s)”). By closely matching the melt temperatures of the contacting materials at the film/spout weld interfaces, preferably at least within 5° C. and most preferably within 2° C., undesirable material displacement at the weld interfaces can be eliminated (presuming substantially homogeneous material temperatures). Research has shown that by reducing and preferably eliminating material displacement during the welding process, weld and/or material failures that might otherwise occur at the weld interface, and/or at areas of the film immediately adjacent to such interfaces, are significantly reduced. Thus, the film weld interfaces, which is usually, but not always, an inner surface of the film at such interface, comprises a material, preferably a LLDPE, that has a melting temperature closely matched to the melting temperature of the material at the spout weld interface, which is usually, but not always, an outer surface of the spout, which is also preferably a LLDPE. In such preferred compositions comprising LLDPE at the film and spout weld interfaces, a convenient means for matching melting temperature requirements is thereby provided.
In certain embodiments of the invention, pre-welded or exposed spout and/or film weld interface material may not be the primary or ultimate bonding media, but may be removed or overcome during the bonding process (as in the case of a volatile coating that is flashed or becomes a flux during bonding operations). However, in presently preferred embodiments, the pre-bonded spout and/or film weld interfaces comprise the closely matched melting temperature materials that form a suitable bond during a bonding or welding process comprising the application of heat and/or radio frequency (RF) energy. Thus, weld material selection is not constrained to that of the spout and/or film outermost or exposed surface, but to the functional material (surface) exposed during bonding operations.
Spout embodiments of the invention also may provide for enhanced spout weld interface surface and sectional characteristics as well as geometries. The surface characteristics comprise substantially flat and/or smooth surfaces, which permit uniform and/or lower material compression pressure to be used during welding, when compared to the prior art. By minimizing sectional thickness differences in adjacent portions of the spout weld interfaces, e.g., no substantial ridges, lands, protrusions or similar positive relief features reside on at least a substantial portion of the spout weld interfaces, displacement/extrusion of film weld interface material(s) is thus greatly minimized. As a consequence, film thickness and integrity at and proximate to the film weld interface can be maintained during and after the bonding process.
Certain embodiments of the immediately preceding type may also comprise negative relief surface features such as holes or depressions defined by the spout weld interface surfaces. As opposed to positive relief surface features, negative relief surface features such as depressions or holes beneficially permit air entrapped between film and spout weld interfaces during boding to escape or not adversely affect the desired weld, thus enhancing the film-to-spout bond. Additionally, such surface features also may accept displaced film/spout material, further enhancing the nature of the bond there between.
The skilled practitioner should appreciate that with respect to the foregoing, spouts having weld interfaces comprising lands and grooves are not equivalent to weld interfaces comprising a generally smooth surface (no positive relief features) but also defining negative relief features, which may include linear negative reliefs. In the former instance, the peaks of the lands do not constitute a “surface” within the meaning of this patent; “surface” as used herein denotes the nominal surface of the material. Moreover, negative surface features of the various invention embodiments are generally limited by the sectional thickness of the spout weld interface; positive relief features have no equivalent limitation.
In addition to the foregoing, spout embodiments of the invention also may comprise at least one stress delocalizing feature (“SDF”), which is particularly useful when spouts according to the invention are used with flexible fluid reservoirs having opposing film panels at the spout weld interface. As noted previously, displacement of reservoir panels at the spout weld interfaces causes the localization of stress along the free edge of the interfaces. This stress localization is often a precursor condition to failure of the weld/bond at the spout/panel weld interfaces. By incorporating at least one SDF, stresses otherwise directed to the interfaces are distributed over a wider area (of both the spout and the panels), thereby reducing the likelihood of failure at the interfaces.
One form of SDF comprises flexible appendages, preferably at the convergence of opposing sides of a spout (the apex of the triangular portions) or at neck portions that form a portion of the spout weld interfaces, which depend beyond the spout weld interface and into the reservoir. These flexible appendages are functionally hinged to the spout weld interfaces such that upon divergent flexing of the opposing film panels, resulting “peeling” forces from the panels to the spout are also imparted to the SDF, thereby reducing the imparted forces to the panels. Thus, the geometry of the SDFs is such that a weld between the spout and the panel experiences reduced peel stress in favor of shear stress. The remaining peel stress is generally directed to the spout itself, which is considerably stronger than the film.
Desirably, SDFs according to several invention embodiments do not have a constant longitudinal profile, nor necessarily a linear edge. A tapered form, preferably comprising a curvilinear edge, appears to most effectively delocalize forces that would otherwise be directed to the spout weld interface.
The prior art heavily relies upon spouts that have a generally rigid body, which is desirable at the spout neck portion where a cap may be fitted, but causes localized stress and abrasion of the flexible film panels when and where bonded thereto. Selected embodiments of the invention may also therefore include spout edges and/or portions of the spout weld interfaces that are flexible in comparison to the neck portion of the spout. Such an arrangement significantly reduce stress and abrasion of the film panels in this area by permitting portions of the spout to flex in response to flexing of the film panels, as opposed to localizing stresses at the spout weld interface periphery. This flexing ability also constitutes a form of an SDF.
Preface: The terminal end of any numeric lead line in the several drawings, when associated with any structure, reference or landmark described in this section, is intended to representatively identify and associate such structure, reference or landmark with respect to the written description of such object. It is not intended, nor should be inferred, to delimit or define per se boundaries of the referenced object, unless specifically stated as such or facially clear from the drawings and the context in which the term(s) is/are used. Unless specifically stated as such or facially clear from the several drawings and the context in which the term(s) is/are used, all words and visual aids should be given their common commercial and/or scientific meaning consistent with the context of the disclosure herein.
Turning then to the several drawings, wherein like parts are numbered the same, and more particularly to
Spout weld interfaces 30 generally include extensions 32a and 32b, each having spout weld interface surfaces 34a and 34b. These surfaces, in conjunction with neck portions 28, form the entirety of the surface that is bonded or welded to opposing film panels 82a and 82b of reservoir 80. Each extension 32 further includes peripheral edges 36 and converging edge 38. It should be noted that peripheral edges 36 and adjacent portions of spout weld interfaces 30 are somewhat flexible in that they are able to converge and diverge relative to each other; this is a result of not having any spanning or structural element restricting such movement. This ability to flex relative to neck portion 20, for example, provides one means for reducing stress and abrasion to film panels 82a and 82b at film weld interfaces 90, and therefore constitutes a form of a Stress Delocalization Feature or SDF.
Returning to spout weld interface surfaces 34a and 34b,
The embodiment shown in
In
| Number | Date | Country | |
|---|---|---|---|
| 61011963 | Jan 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2009/000481 | Jan 2009 | US |
| Child | 12842002 | US |
