Patent Application
20170362006
The present invention relates generally to packaging articles and more particularly, to manually openable packages formed from a first flexible heat shrinkable film and a second flexible non-heat shrink film. The present invention also includes an opening tab on each of the two flexible films which are aligned with each other such that each of the opening tabs has a sufficient surface area facing the other tab but not adhered to it to render each tab manually graspable. A distal portion of the opening tab of the first flexible heat shrinkable film is curled to provide a more convenient means of gripping the opening tab which may then be pulled away from the second flexible non-heat shrinkable film to open the package.
Typical flexible thermoplastic packages which provide the desired abuse protection and other desirable features in the finished package are usually designed to have strong heat seals when sealed about a product. These packages after heat sealing are often difficult to open by the consumer or end user. It has been therefore desirable to have a package which provides adequate protection of the product against environmental contaminants, moisture and air, and which includes sufficiently strong heat seals to maintain the integrity of the package through the distribution channels and storage, and at the same time can be easily opened by the consumer without the use of a knife or other cutting implement.
The present invention is directed to packages having a thermoformed product receiving cavity for containing the product formed from a first flexible heat shrinkable film and a lidding film covering the thermoformed product receiving cavity formed from a second flexible non-heat shrinkable film. The present invention includes a hermetic seal comprising a perimeter heat seal circumventing the thermoformed product receiving cavity formed by heat sealing a portion of the second flexible non-heat shrinkable film to a portion of the first flexible heat shrinkable film; wherein only one of the films is readily frangible and renders the heat seal manually peelable. The readily frangible film includes either a cohesively peelable layer which separates from itself or an adhesively peelable layer which delaminates from an adjacent layer thereby creating a peelable interface. The present invention also includes an opening tab on each of the two flexible films which are aligned with each other such that each of the tabs has a sufficient surface area facing the other tab but not adhered to it to render each tab readily manually graspable. The opening tabs are conveniently provided by aligning portions of the two films which lie outside the heat seal which joins them to each other and by minimizing or eliminating their exposure to heat and pressure.
An important aspect of the present invention is that the opening tab of the first flexible heat shrinkable film includes a distal portion which is curled to improve its graspability. The curled distal portion of the opening tab of the heat-shrinkable film is formed when the film is heat shrunk around the product. Since one of the tabs has a curled portion while the other is substantially relatively flat, the opening tabs may be easily grasped and pulled away from each other. When the opening tabs are pulled in a direction generally perpendicular to the plane of the perimeter heat seal, the readily frangible film will cleanly peel apart from itself and rupture the hermetic seal thereby opening the package.
In one preferred embodiment, the package has a shape which includes at least one corner and at least one pair of opening tabs positioned at the corner. In another preferred embodiment, the package includes multiple corners and at least one pair of opening tabs positioned at a corner of the package. In yet another preferred embodiment, the package includes multiple corners and more than one pair of opening tabs positioned at the corners of the package. It is also contemplated that the package may have a shape which is substantially curved and does not include any defined corners, in which case, the opening tabs may extend around a portion or the entire length of the perimeter heat seal.
Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:
“Peelable” and like terminology is used herein to refer to any substrate interface which are engineered to be readily peelable (or delaminate within a particular film layer or between two film layers) without uncontrolled or random tearing or rupturing the packaging materials which may result in premature destruction of the packaging film and package made therefrom. A peelable interface or peelable layer is one that can be manually peeled apart to open a package without resorting to the use of a knife or other implement to tear or rupture the web. In the present invention, the peelable layer or peelable interface must have seal strengths sufficient to prevent failure of the seal during the normal filling process and further normal handling and transport of the packaged article. The seal strengths must also be low enough to permit manual opening of the seal. Preferably, parameters such as choice of materials and lamination conditions may be used to adjust the seal strength to the desired level for the particular package web and packaging application. A peelable layer or peelable interface according to the present invention has an initial seal strength set to a maximum value of 2,500 gram-force/inch and a propagation seal strength (i.e., tearing force) set to a range from between 60 and 2,500 gram-force/inch. In contrast, a non-peelable layer or non-peelable interface is not adapted to peel apart or delaminate in a controlled manner as described above. Non-peelable layers or non-peelable interfaces have initial seal strengths of at least 2,000 gram-force/inch, typically at least 2,500 gram-force/inch.
“Heat Shrinkage” values are obtained by measuring unrestrained shrink of a 10 cm2 sample immersed in water at 90° C. (or the indicated temperature if different) for two to ten seconds. Four test specimens are cut from a given sample of the film to be tested. Specimens are cut into squares of 10 cm length in the machine direction (M.D.) by 10 cm. length in the transverse (T.D.). Each specimen is completely immersed for 2-10 seconds in a 90° C. (or the indicated temperature if different) water bath. The specimen is then removed from the bath and the distance between the ends of the shrunken specimen is measured for both the M.D. and T.D. directions. The difference in the measured distance for the shrunken specimen and each original 10 cm side is multiplied by ten to obtain percent shrinkage in each direction. The shrinkage of 4 specimens is averaged and the average M.D. and T.D. shrinkage values reported. It should be noted that heat shrinkable films referred to herein are uniaxially or biaxially oriented film. Preferred heat shrinkable films suitable for the present invention have a Heat Shrinkage value of greater than 10% or 20% or 30% or 40% in both machine and transverse directions as measured at 90° C. for 10 minutes. In contrast, preferred non-heat shrinkable films suitable for the present invention have a Heat Shrinkage value of between 0 and 10% in both machine and transverse directions as measured at 90° C. for 10 minutes.
Referring to
Once the product receiving cavity is formed, a desired product 80 may then be placed within the cavity. Typically, the product is a cheese or meat item, but non-food products can be packaged as well. A non-forming lidding film 40 comprising a second flexible non-heat shrinkable film 200 (see
It is important to note that before the heat sealing operation, a portion 35a of the projected flange 30 of film 100 and a portion 35b of film 200 are aligned with each other outside the perimeter heat seal 60 and have sufficient surface area facing each other or size to be manually graspable. In one preferred embodiment, portions 35a and 35b are isolated from heat and/or pressure during the heat sealing operation and are not sealed together thereby providing an opening tab 75a of film 100 and an opening tab 75b of film 200. In another preferred embodiment, opening tabs 75a and 75b may be formed by treating portion 35a of the projected flange 30a of film 100 and/or portion 35b of film 200 to render one or both portions non-adherent. This may be accomplished by printing a release lacquer or varnish on one or both portions before heat sealing the films together. Alternatively in another embodiment, opening tabs 76a and 75b may be formed by inserting a heat resistant material such as for example Teflon tape between portion 35a of the projected flange 30 of film 100 and portion 35b of film 200 such that the portions do not come into contact with each other during the heat sealing operation. It should also be noted that neither tab 75a nor 75b needs to be heat set prior to the heat sealing operation. In one preferred embodiment, at least one of the opening tabs has at least one dimension of at least about 2 mm (about 0.08 in). In another preferred embodiment, at least one of the opening tabs has at least one dimension of at least about 6 mm (about 0.236 in). In yet another preferred embodiment, at least one of the opening tabs has at least one dimension of at least twice the width of the perimeter heat seal 60.
Once the heat sealing operation is complete, any excess film surrounding the perimeter of the package may be removed thereby individualizing each package. After each package has been separated, they are then exposed to heat to shrink the heat shrinkable film 100 of the cavity 20 about product 80. In one preferred embodiment, the first flexible heat shrinkable film 100 is heat shrunk about the product in a shrink tunnel such as a water bath between a temperature of 80° C. and 90° C. for about 1 to 5 seconds. During this shrink operation, heat shrinkable film 100 forms to the shape of the product. In one preferred embodiment, the first flexible heat shrinkable film 100 shrinks in a uniform manner as to provide a wrinkle-free product receiving cavity 20. Heat shrinkable film 100 will typically exhibit a heat shrinkage value of greater than 10% or 20% or 30% or 40% in both machine and transverse directions as measured at 90° C. for 10 minutes. In one preferred embodiment, film 100 has heat shrinkage value of about 40% in the machine direction and about 44% in the transverse direction at 90° C. In contrast, a non-heat shrinkable film such as film 200 will typically exhibit a heat shrinkage value of less than 30% or 20% or 10% in both machine and transverse directions as measured at 90° C. for 10 minutes.
As the result of the heat shrinkage of first flexible film 100, a curled distal portion 75a on the opening tab 35a is formed. As depicted in
Turning now to
As used herein, the term “sealant” refers to a layer which is heat sealable to itself or to other materials, i.e., be capable of fusion bonding by conventional heating means which generate sufficient heat on at least one film contact surface for conduction to the contiguous film contact surface and formation of a bond interface therebetween without loss of the film integrity. Advantageously, the bond interface must be sufficiently thermally stable to prevent gas or liquid leakage therethrough. Suitable sealant materials include, but are not limited to polyolefins, such as polyethylenes (PE), including low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), and ultra-low density polyethylene (ULDPE); ethylene vinyl acetate copolymers (EVA); ionomers; and blends thereof.
The term “adhesive layer,” or “tie layer” refers to a layer or material placed on one or more layers to promote the adhesion of that layer to another surface. Typically, adhesive layers are positioned between two layers of a multilayer film to maintain the two layers in position relative to each other and prevent undesirable delamination. Unless otherwise indicated, an adhesive layer can have any suitable composition that provides a desired level of adhesion with the one or more surfaces in contact with the adhesive layer material. Optionally, an adhesive layer placed between a first layer and a second layer in a multilayer web may comprise components of both the first layer and the second layer to promote simultaneous adhesion of the adhesive layer to both the first layer and the second layer to opposite sides of the adhesive layer. Tie or adhesive layers may be incorporated into a film or laminate by any of the well-known processes for making multilayer structures such as coextrusion, adhesive lamination and the like. Typical tie materials include, but are not limited to anhydride or carboxylic acid modified polyolefins, particularly, maleic anhydride modified polyolefins such as maleic anhydride modified low density polyethylene, maleic anhydride modified linear low density polyethylene, maleic anhydride modified high density polyethylene, maleic anhydride modified ethylene vinyl acetate copolymers and blends thereof. Tie layer materials may further include a blend of an unmodified polyolefin or unmodified ester copolymer or unmodified ethylene acid copolymer and a modified polyolefin or modified ester copolymer or modified ethylene acid copolymer.
Frangible or peelable film layers are well known in the art and are disclosed in U.S. Pat. No. 4,944,409 (Busche et al.); U.S. Pat. No. 4,875,587 (Lulham et al.); U.S. Pat. No. 3,655,503 (Stanley et al.); U.S. Pat. No. 4,058,632 (Evans et al.); U.S. Pat. No. 4,252,846 (Romesberg et al.); U.S. Pat. No. 4,615,926 (Hsu et al.) U.S. Pat. No. 4,666,778 (Hwo); U.S. Pat. No. 4,784,885 (Carespodi); U.S. Pat. No. 4,882,229 (Hwo); U.S. Pat. No. 6,476,137 (Longo); U.S. Pat. No. 5,997,968 (Dries, et al.); U.S. Pat. No. 4,189,519 (Ticknor); U.S. Pat. No. 5,547,752 (Yanidis), U.S. Pat. No. 5,128,414 (Hwo); U.S. Pat. No. 5,023,121 (Pockat, et al.); U.S. Pat. No. 4,937,139 (Penske, et al.); U.S. Pat. No. 4,916,190 (Hwo); and U.S. Pat. No. 4,550,141 (Hoh), the disclosures of which are incorporated herein in their entirety by reference thereto. In one preferred embodiment, the frangible layer of second film 200 includes a blend of two different polymer resins. Non-limiting examples of such blends combine polyethylene such as low density polyethylene, linear low density polyethylene or ethylene vinyl acetate copolymer as a major component with a polybutylene-1 as a minor component. The major component of these blends is present in an amount of at least 50%, 60%, 70%, 80% or 90% by weight relative to the total weight of the frangible layer. Typically, these frangible layers provide a relatively weak bond to an adjacent layer whereby the interface between these layers delaminates upon application of force perpendicular to the plane of the interface.
Oxygen barrier materials may include, but are not limited to, polyamides, ethylene vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVdC), metal or metal oxide coated polymer substrates and the like. In one preferred embodiment of the present invention, both first and second films, 100 and 200, include at least one layer comprising an oxygen barrier material. In another preferred embodiment, both first and second films, 100 and 200, include at least two layers each comprising an oxygen barrier material. In yet another preferred embodiment, both first and second films, 100 and 200, include at least three layers each comprising an oxygen barrier material. However, it should be noted that the present invention does not necessarily require that one or both of the first and second films, 100 and 200, include a layer comprising an oxygen barrier material. But, those skilled in the art will recognize that when packaging an oxygen sensitive product which may include many food items, at least one layer of an oxygen barrier material may be required in one or both films of the present invention to provide a barrier against the ingress of oxygen.
Abuse materials may include, but are not limited to, polyolefins such as polyethylenes (PE) and polypropylenes (PP); polyamides; polyamide blends; polyesters including aromatic and aliphatic polyesters, such as polyethylene terephthalates (PET), polyethylene isophthalates, polyethylene naphthalates; oriented polyamides and oriented aromatic polyesters. Typically, abuse materials provide additional moisture and/or chemical barrier protection to a film. Those skilled in the art will recognize that abuse materials also provide a sufficiently smooth surface for the printing of indicia or graphics that appear on most packaged food or non-food products. In one preferred embodiment of the present, the abuse layer of at least one of the first or second films, 100 or 200, includes printed indicia.
In the following Example 1, the film structure for first flexible heat shrinkable film 100 depicted in
In the following Example 2, the film structure for first flexible non-heat shrinkable film 200 depicted in
Example 1 is one embodiment of a first flexible heat shrinkable film 100 of the present invention having a layer sequence (in the order as shown below) and layer compositions as described below and as illustrated in
Example 2 is one embodiment of a second flexible non-heat shrinkable film 200 of the present invention having a layer sequence (in the order as shown below) and layer compositions as described below and as illustrated in
The above description and examples illustrate certain embodiments of the present invention and are not to be interpreted as limiting. Selection of particular embodiments, combinations thereof, modifications, and adaptations of the various embodiments, conditions and parameters normally encountered in the art will be apparent to those skilled in the art and are deemed to be within the spirit and scope of the present invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US14/67010 | 11/24/2014 | WO | 00 |
