Patent Application
20050089250
1. Field of the Invention
This invention relates to a flexible container, particularly a flexible container having a seal with non-linear seal portions, wherein forces exerted on the seal by fluid materials contained within the flexible container are more evenly distributed along the seal, and forming an extended opening for easy access to a void without increasing the overall width of the flexible container.
2. Description of Related Art
Under new Federal Aviation Administration (FAA), in the United States, testing criteria in the United States, a container must be able to withstand a sustained internal pressure of about 14 psi for at least about 30 minutes in order to be suitable for transporting toxic and other hazardous materials, using air transportation. For example, if an airplane traveling at an elevation of about 42,000 feet is depressurized, the container must withstand a net effect of an internal pressure of about 14 psi in order to remain sealed. Many conventional containers, particularly flexible containers, cannot withstand such high internal pressure. As a result, a conventional flexible container leaks through a closure which sealably closes a container opening, breaks at a weak peripheral seal or deforms or expands at a region and develops an opening, whereby the materials contained within the container leak from the container.
For example, it is very difficult to provide a flexible container that can withstand high internal pressures and maintain a leak-proof closure. Conventional flexible containers typically have a general rectangular void area when in a flat or uninflated condition. The seal which forms the void is positioned about a periphery of the flexible container and includes a bottom portion, a top portion and opposing side edge portions. The seal portions are generally linear or straight. As a result, when the flexible container is inflated or filled with a fluid material and subjected to increased internal pressure, forces exerted on the side walls and the seal cause a center of the seal portions to be pulled inward toward the void, thus causing the seals to form an hour-glass shaped void. This causes even greater forces to be exerted on the seal which may result in failure of the seal at a weak portion of the seal or closure area and leakage of the material contained within the flexible container, particularly when the flexible container is subjected to a high internal pressure.
There is an apparent need for a flexible container wherein forces exerted by the material contained within the flexible container on the seal are reduced and/or more evenly distributed along the seal.
There is also an apparent need for a flexible container wherein portions of the seal are generally linear when filled with a fluid material.
There is also an apparent need for a flexible container which provides an increased opening for placing material within the flexible container without increasing the overall width of the flexible container.
It is an object of this invention to provide a flexible container having a seal with non-linear seal portions when in a flat or uninflated condition, to more evenly distribute forces exerted on the seal when fluid materials are contained within the flexible container.
It is another object of this invention to provide a flexible container that provides an increased opening to provide access to the void formed by the flexible container while providing seal portions which distribute forces more evenly along the seal.
The above and other objects of this invention are accomplished with a flexible container having at least two webs positioned and sealed with respect to each other about a periphery of the flexible container, to form a void between the webs. In one preferred embodiment of this invention, the first web and/or the second web includes two or more layers of material. For example, the first web may include a first or outer layer made of a polymer material, such as a polyester or nylon or other similar material, and a second or inner sealant layer made of a polymer material, such as a polyethylene material. Similarly, the second web may include a first layer and a second layer. Preferably, but not necessarily, the first layer of the second web includes a material the same or similar to the first layer of the first web and the second layer comprises a material the same or similar to the second layer of the first web. Alternatively, the first layer and the second layer of the second web may include a different material than the first layer and the second layer of the first web, respectively.
At least one seal joins or seals the first web with respect to the second web and forms the void between the webs. The seal is preferably formed about a periphery of the flexible container using any suitable sealing process, for example a heat sealing process and/or an adhesive sealing process. It should be apparent to those skilled in the art that other suitable sealing processes may be used to form the seal. Additional seals may be formed and positioned with respect to the void. For example, a second seal, continuous or segmented, can be formed within the primary seal to maintain the void in a proper configuration or shape.
Preferably, at least one seal is continuous and at least an inner edge of at least one portion of the seal is non-linear. In one embodiment of this invention, an inner edge of at least one portion of the seal has an arcuate shape. For example, an inner edge of at least one of a bottom portion, a top portion and/or opposing side edge portions of the seal has an arcuate shape. Preferably, the arcuate-shaped inner edge of the portion or portions of the seal are bowed outward from the void.
In one preferred embodiment of this invention, the inner edge of the bottom portion of the seal is bowed outward from the void. Preferably, the inner edge of the bottom portion follows an arc segment wherein a height of the arc segment, as defined below, is at least about 0.125 inch. Additionally or alternatively, at least a portion of the inner edge of at least one opposing side edge portion is bowed outward from the void, in a direction from a top to a bottom of the respective opposing side edge portion. Similarly, the non-linear or arcuate inner edge of opposing side edge portions of the seal follow an arc segment wherein a height of the arc segment is at least about 0.125 inch. In one preferred embodiment of this invention, the opposing side edge portions converge in a direction toward the bottom portion of the seal. Additionally, near a closure area formed or defined by the flexible container, at least the inner edge of the opposing side edge portions of the seal may diverge from each other in a direction from the bottom to the top of the side edge portions to provide a large or extended opening in the closure area. An inner edge of the top portion of the seal may also be non-linear, for example arcuate. The inner edge of the top portion may be bowed outward from the void. Preferably, the inner edge of the top portion follows an arc segment wherein a height of the arc segment is at least about 0.125 inch.
The flexible container also includes a closure area defined by the first web. The closure area forms an opening which provides access to the void. In one preferred embodiment of this invention, the opening includes a slit positioned along a fold line that passes through the closure area. Preferably, but not necessarily, at least one of the first web and the second web has a structural relief near at least one of opposing end portions of the slit. The structural relief includes at least one layer of at least one of the first web and the second web having a reduced thickness at the fold line. A layer of adhesive is applied to the first web at the closure area to provide a tight leak-proof seal about the opening when a top portion of the flexible container is folded along the fold line with respect to a bottom portion of the flexible container and about the opening.
Other objects and advantages of this invention will be apparent to those skilled in the art from the following detailed description taken in conjunction with the appended claims and drawings.
The drawings show different features of a flexible container, according to preferred embodiments of this invention, wherein:
Referring to
The term “flexible” refers to the ability of flexible container 10 to bend, stretch, expand or contract, for example, without permanent deformation or failure, to adapt to changing environments, for example a change in pressure or change in temperature. It is apparent that flexible container 10 and/or void 28 formed between webs 20, 40 can have any suitable shape and/or dimensions which allows flexible container 10 to function properly for a particular purpose. Flexible container 10 may comprise at least one component or element similar to a corresponding component or element as taught in U.S. Pat. No. 5,336,123 issued to Laske et al. on Aug. 9, 1994 and/or as taught in copending, commonly owned U.S. patent application Ser. No. 10/165,633, filed on 7 Jun. 2002 naming Louis L. Laske as the inventor, the disclosures of which are incorporated by reference into this specification.
Throughout this specification, as discussed above, one side of flexible container 10 may include one or more first webs 20 and the opposing side of flexible container 10 may comprise one or more second webs 40. As different elements and features are discussed throughout this specification, when referring to one first web 20 and/or one second web 40, such discussion can be interchanged with discussion related to either side of flexible 10 having two or more first webs 20 and/or two or more second webs 40.
In one preferred embodiment of this invention, each web 20, 40 has a total thickness of about 0.003 inch to about 0.010 inch and comprises at least two layers of material that are coextensive. The term “coextensive” as used throughout this specification and in the claims refers to the positioning of web 20 with respect to web 40, wherein web 20 is aligned with web 40 such that web 20 and web 40 generally have the same or similar outer boundaries, for example boundaries forming the edges of flexible container 10. In one preferred embodiment of this invention, first web 20 includes a first or outer layer made of a polymer material, such as a polyester or nylon or other similar material, having a thickness of about 0.00025 inch to about 0.0015 inch and a second or inner sealant layer made of a polymer material having a thickness of about 0.0005 inch to about 0.006 inch. The first layer may comprise a 0.00060 inch, for example, biaxial oriented nylon material, such as available from Clear-Lam, located in Illinois, United States. The biaxial oriented nylon material provides a strong structure due to equal or similar tensile strengths in the longitudinal direction and the lateral direction of the material. Preferably, the second layer comprises a 0.0015 inch polyethylene material, such as available from Southern Films located in Florida, U.S.A., a material which is known as a linear low density polyethylene. Other suitable materials known to those skilled in the art may be used to make the first layer and/or the second layer of first web 20 and/or second web 40.
Similarly, second web 40 may include a first layer and a second layer. Preferably but not necessarily, the first layer comprises a material the same or similar to the first layer of first web 20 and the second layer comprises a material the same or similar to the second layer of first web 20. Alternatively, the first layer and the second layer may comprise a different material than the first layer and the second layer of first web 20, respectively. In one preferred embodiment of this invention, first web 20 and second web 40 each comprises a third layer sealed with respect to the first and second layers. For example, a third layer (not shown) made of 0.0015 inch polyethylene, for example, may be sealed with respect to the first layer to sandwich or position the first layer between the second layer and the third layer.
The first layers and the second layers, and any additional layers, may be made of any suitable compatible materials, for example polymer materials, which when combined to form one or more of each of webs 20, 40 exhibit a combined strength capable of withstanding a wide pressure and/or temperature range. The multiple layer, multiple web construction of flexible container 10 provides a strong structure because one layer supports the other layer. Preferably, flexible container 10 is capable of withstanding a constant or sustained internal pressure of at least about 14 psi. The closure at closure area 62 and the corresponding material of the closure can withstand temperatures of about −40° F. to about 130° F., without deformation of and/or leakage through the closure.
Preferably, first web 20 and second web 40 are heat sealed to form a seal 30 about a periphery of flexible container 10, as shown in
Referring to
Preferably, at least an inner edge of at least one portion of seal 30 is non-linear. For example, referring to
Referring to
Preferably, but not necessarily, each arcuate-shaped portion of seal 30 is bowed outward from void 28. Referring to
Referring to
As shown in
Referring further to
In one embodiment of this invention, flexible container 10 further comprises a second seal 39 positioned inward with respect to void 28, as shown in
Referring to
An adhesive layer 68 is applied to at least a portion of first web 20 at closure area 62. Any suitable adhesive known to those skilled in the art can be used to form adhesive layer 68, which provides a sufficiently strong adhesive seal to close opening 60. A cover strip 50 can be applied to or positioned on adhesive layer 68, such that adhesive layer 68 is sandwiched or positioned between first web 20 at closure area 62 and cover strip 50. Preferably, cover strip 50 and adhesive layer 68 form a pressure sensitive tape material, as is well known in the art. The pressure sensitive material can be applied as a preformed material or can be applied in manufacturing steps as adhesive layer 68 and cover strip 50.
In one preferred embodiment of this invention, at least one web 20, 40 has at least one structural relief 69. As shown in
In one preferred embodiment of this invention, structural relief 69 comprises a notched area 70 formed in one or more layers of web 20 and/or one or more layers of web 40 and extending a distance on one or both sides of fold line 99, as shown in
Referring to
In one embodiment of this invention, when flexible container 10 is folded about fold line 99, adhesive layer 68 folds over onto itself to form an adhesive-to-adhesive bond and/or folds over onto an outer surface of first web 20 to form an adhesive-to-layer bond. In either case, because of the shape memory or bias force within the layer at fold line 99 the layer has a tendency to unfold or open flat. By applying more pressure to the layer at fold line 99, the adhesive-to-adhesive and/or the adhesive-to-layer bond strength is increased. Providing one or more notched areas 70 at fold line 99 allows more direct pressure applied at fold line 99 which enhances the bond strength provided by adhesive layer 68 and reduces the shape memory as well.
While in the foregoing specification the invention has been described in relation to certain preferred embodiments, and many details are set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described in the specification and in the claims can be varied considerably without departing from the basic principles of the invention.
