Patent Application
20090301034
The present invention relates to sealed containers. More specifically, the present invention relates to containers, such as plastic bags wherein the containers can be compressed or evacuated to remove excess air, fluid or gaseous content and then sealed in such compressed or evacuated arrangement.
Bag like containers have been used to store a large number of materials. One drawback of these devices is that during the filing and sealing process, they tend to trap air, fluid or other gaseous materials within the confines of the container. This excess gaseous material can make it difficult to stack the containers and may also contributed to a reduction in the amount of product that can be stored, shelved or transported within a given area. The presence of the gas can also contribute, in some instances, to reduced shelf life of the product due to spoilage.
Paper bags, due to the porous nature of the construction (formed from cellulosic stock), can allow trapped gases to escape after closure of the container, but this venting of the bag is a slow process. Likewise, due to the porous nature of the construction of the paper bags, gases and moisture can flow back into the container. Hence, spoilage of the contents can occur due to moisture or in the case of oxygen, oxidation of the contents. Perforations added to the paper container can help in the expulsion of the unwanted gaseous elements from the container, but may then contribute to accelerating the process of gases reentering the container.
Plastic bags on the other hand, depending on the materials of construction, provide either a partial or complete barrier to gaseous products entering the container, but also create a barrier to removing gases from the closed container. Perforations have been heretofore added to the containers to facilitate the removal of excess gaseous contents, but again suffer in that these perforations allow later gaseous uptake by the container. These perforations can also allow contents of smaller size that have a diameter or shape that is smaller than the diameter of the perforation to escape from the container. The result is spillage and loss of the overall content of the container.
U.S. Pat. No. 6,378,272 to Archibald proposes a solution to evacuating a plastic container by creating a valve like flap that extends over the perforations. When the gas within the container is expelled, the gaseous flow causes the adhesive affixed to the flap to release from its surface and thereby allows the flap to separate from or depart contact within the area of the hole and allows the gas to escape. Once the gaseous flow is reduced, the flap can be reaffixed to the surface within the vicinity of the hole and seal the opening so as to retard or prevent the later entrance to the container by gaseous elements. This design suffers for at least two reasons. First, creation of this flap and placement of the adhesive adds cost to the overall of the construction. Secondly, the adhesive of this device can not have high peel strength or the flap will not open properly during the evacuation of the container. That, is the flap must be sufficiently releasable from the surface of the container (the adhesive doe not permanently bond to the container) to allow the gas to escape. This ability to easily open may also be a detriment to the container. Such containers are usually stacked upon each other, transported and then placed in various configurations for sale, such as with store shelves. The handling of the container and its contact with other surfaces can cause the weakly held adhesive flap to open and hence expose the contents to the environment, and allow gas, dust or other debris to enter the container. Whenever attempts have been made to increase the peel strength of the adhesive to a valve suited to eliminate inadvertent flap opening, the resultant device did not release properly during container evacuation.
The embodiments of the present invention described below are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention.
This invention provides a method for creating a more economical and effective way of preparing a container that can be effectively evacuated, yet one that can be effectively sealed against gaseous/fluid transmission with less risk of failure of the sealing mechanism.
In one exemplary embodiment, a method is described for preparing a container with perforations that includes the steps of initially introducing a material into the container, then sealing the container. The excess gaseous contents are removed from the container through evacuation or compression. Finally, a nonporous patch is affixed over the perforations using a permanent type adhesive resin.
In another exemplary embodiment, an article is described which is a container with at least one perforation creating a perforated area and an adhesive patch permanently adhered atop the perforated area.
In a still further exemplary embodiment, substantially quadrate container, is presented and includes a pouch that is formed from a flexible sheet material having an oxygen transmission rate of less than about 10 cc/100 in (645 cm2)/24 hr/atm at 100° F. The pouch has first and second longitudinally extending sides and first and second transversely extending end edges. The first and second longitudinally extending sides and transversely extending edges define first and second outside surfaces.
Continuing with the presently described embodiment, an exit port is provided and extends through the first outside surface to a first inside surface, the exit port has an edge. A porosity mechanism is placed immediately adjacent the exit port on the first inside surface and substantially covers and extends beyond the edge of the exit port. An adhesive patch is placed over so as to cover the exit port on the first outside surface of the pouch. The adhesive patch having a pattern of adhesive that extends around a perimeter of the adhesive patch and outside of the edge of the exit port, the adhesive patch further including a plurality of microperforations having dimensions ranging from about 0.2 mm to 0.4 mm.
The embodiments of the present invention described herein are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present invention.
These and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.
These, as well as other objects and advantages of this invention, will be more completely understood and appreciated by referring to the following more detailed description of the presently preferred exemplary embodiments of the invention in conjunction with the accompanying drawings, of which:
The present invention is now illustrated in greater detail by way of the following detailed description which represents the best presently known mode of carrying out the invention. However, it should be understood that this description is not to be used to limit the present invention, but rather, is provided for the purpose of illustrating the general features of the invention.
The present invention relates to sealed containers. More specifically, the present invention relates to containers, such as plastic or synthetic, flexible bags wherein the containers can be compressed or evacuated to remove excess air or fluid content and may be sealed.
In the case of a pouch 10, one of the exemplary methods that may be used for forming the pouch, adding the contents, and sealing the open end of the pouch is by using a “Form, Fill, Seal Machine (FFS)”. These machines can be purchased from various suppliers including Magnum Industries of Kansas City, Kansas and Sandi Acre Packaging Machinery of Nottingham, UK.
Additionally, if the material 12 is of smaller size than exit port 18, that is, the particulate size, shape or diameter is smaller than the diameter of the exit port, a porosity mechanism 19 may be affixed to the inside surface 17 adjacently covering the exit port 18, so as to retain the material 12 within the container 10.
The pouch 13 comprises a non-porous flexible material such as polypropylene and/or polyethylene plastic film. The flexible material is laminated or can be a single layer, multilayer film. The film material can be a polymer, co-polymer or melt blends of various plastics. It can include construction of foil like materials, either as part of a laminate or as a single layer construction. Material selection should be appropriate for the duration and environmental exposure anticipated during the product life cycle. For instance, if the container is outside in a tropical environment, the container would need to be UV and moisture stable in order to withstand the exposure to sunlight and humidity respectively. Likewise, the container should be inert to the chemical contents contained therein. Fertilizers, oxidizers and corrosive materials are good examples. Other examples of environmental considerations might include resistance to insects and mites.
Sealing mechanism 15, in a closed position, prevents the material 12 from exiting pouch 13 as illustrated in
In one embodiment, a porosity mechanism 19 is utilized. This mechanism functions to allow excess gaseous contents, but not other material 12 in pouch 13, to be expelled when the container is squeezed, i.e., forced out of pouch 13 or placed under vacuum to withdraw the gaseous material. The excess gas passes through porosity mechanism 19 out through exit port 18 to form an aspirated container.
Porosity mechanism 19 can have a different porosity depending on the size of the particle 12 being stored in pouch 13. The larger the particles 12, the greater the porosity can be of porosity mechanism 19. Some examples of possible porosity mechanisms 19 would be perforated strips and non-woven or spun bonded fabrics. Preferably, a porosity mechanism 19 has a construction or design so that it does not become clogged with particulate material which could impede the expiration of the entrapped air 12 when excess gas is squeezed out of pouch 13. That is, particulate material may be picked up by the gas/fluid flow and carried to the exit port.
The non-porous patch 20 can be made out of the same material as the container or may be constructed of other materials that provide the needed flexibility and barrier properties required. The non-porous patch may be constructed of polymer flexible film or foil films. Alternately the non-porous patch 20 can be constructed of a porous material such as paper, which may either be coated with a sealing material, such as silicone or wax or the adhesive may be sufficient impermeable to prevent gas/fluid flow through the paper.
The adhesive layer of the non-porous patch 20 is selected so as to provide sufficient tack at expected use temperatures (temperatures ranging from about 55° F. to about 100° F. or those found in warehouses, retail outlets and some transport configuration). These adhesives will rapidly build bond strength in a short period of time to achieve a permanent bond which precludes removal of the non-porous patch 20. The adhesive coverage on the surface of the patch 20 may be complete or it may partially cover the surface of the patch 20. It is preferable however that the adhesive area around the perimeter of the patch 20 be continuous so that no pathway exists for gas to pass between the patch 20 and the surface of the container or pouch 10. The adhesive can be a pressure sensitive adhesive, heat activated adhesive, or heat applied adhesive. Alternatively, a pattern of adhesive may be used, such as overlapping strips or segments which still create an effective seal against air or gaseous egress or ingress.
The amount of pressure-sensitive adhesive employed in these constructions may range from about 1 to about 100 grams/m2, and more often, the amount is in the range from about 15 to about 45 grams/m2, and still more preferably 15 to about 30 grams/m2. A variety of pressure-sensitive adhesives can be utilized including hot-melt adhesives, water-based adhesives such as water soluble or water dispersible adhesives, and solvent-based or organic soluble adhesives. Such adhesive compositions are described in, for example, “Adhesion and Bonding”, Encyclopedia of Polymer Science and Engineering, Vol. 1, pages 476-546, Interscience Publishers, 2nd Ed. 1985 and are available from Avery Dennison Corporation, Pasadena, Calif. Such compositions generally contain an adhesive polymer such as natural, reclaimed or styrene-butadiene rubber, styrene butadiene or styrene isoprene block copolymers, polyisobutylene, poly(vinyl ether) or poly(acrylic) ester as a major constituent. Other materials may be included in the pressure-sensitive adhesive compositions such as resin tackifiers including, for example, rosin esters, oil-soluble phenolics, or polyterpenes; antioxidants; plasticizers such as mineral oil or liquid polyisobutylenes; and fillers such as zinc oxide or hydrated alumina.
In applications where moisture sensitivity of the product is an issue, a low moisture vapor transmission rate (MVTR) adhesive can be employed. Preferably, the adhesive layer has a moisture vapor transmission rate (MVTR) of less than 10 g/(m2*24 h), preferably of less than 1.1 g/(m2*24 h), measured according to DIN 53122 at a temperature of 23° C. and a relative humidity of 85%. These tests can be performed using a Honeymoon Model W 825 Water Vapor Transmission Rate Tester (Honeywell, Inc., Minneapolis, Minn.).
In applications where oxygen sensitivity of the product is an issue, a low oxygen transmission rate (OTR) adhesive can be employed. Preferably, the adhesive layer has an oxygen permeability rate of less than about 10 cc/10 in (645 cm2)/24 hr/atm at 100° F. (38° C.), more preferably, less than about 1.0 cc/100 in (645 cm2)124 hr/atm at 100° F. (38° C.). The aforesaid oxygen transmission rates can be determined by various methods known in the art. For example, these rates can conveniently be measured with a Dohrmann Polymeric Permeation Analyzer, PPA-I (Dohrmann Envirotech Corporation, Mountain View, Calif.). The Dow Cell can also be employed for this purpose, in accordance with ASTM procedure D-1434.
In some applications it may be desired to have very small vent holes (exit ports). The desire for these small vent holes may be due to cosmetic or structural considerations or may be used as a retention device when small particle size contents are present. In these applications microperforations may be required. Microperforations include slits or round holes having a maximum dimension of about 0.2-0.4 millimeters. In a preferred embodiment of the invention, perforations comprise slits or round holes having a maximum dimension of about 0.3 millimeters so that they are essentially invisible to the naked eye. These microperforations can be made via mechanical puncturing methods but can also be made using lasers. Examples of microperforations include U.S. Pat. No. 5,171,593 to Doyle, U.S. Pat. No. 5,405,561 to Dais and U.S. Pat. No. 6,146,731 to Tanoto.
The pouch structures of this invention can be prepared from sheets of material which are folded upon themselves in any number of configurations. Seams are typically glued or welded together. Likewise the pouches can be constructed from cylindrical tubes of material. These tubes, for example, can be prepared using a circular extrusion die with air introduced internal to the tube in order to prevent collapse of the tube prior to cooling of the film. These “blown films” are well known in the industry. By collapsing the tube to a flat structure, cutting to suitable length and by sealing the open end, a pouch can be constructed. Examples of blown films include EP 1111B 1 to Pannenbecker and U.S. Pat. No. 4,354,997 to Mizutani.
It will thus be seen according to the present invention a highly advantageous container has been provided. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it will be apparent to those of ordinary skill in the art that the invention is not to be limited to the disclosed embodiment, and that many modifications and equivalent arrangements may be made thereof within the scope of the invention, which scope is to be accorded the broadest interpretation of the appended claims so as to encompass all equivalent structures and products.
The disclosures of all patents mentioned herein are hereby incorporated by reference and may or may not be prior art.
The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of their invention as it pertains to any apparatus, system, method or article not materially departing from but outside the literal scope of the invention as set out in the following claims.
The present application claims the benefit of U.S. Provisional Application No. 61/060,141 filed Jun. 10, 2008, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61060141 | Jun 2008 | US |
