Shrink bag with integral handle and method of making the same

Abstract: A shrink bag having one end (24) heat sealed to form the closed end of a bag pocket and including a skirt portion at this closed end which forms a handle (42) upon heat shrinking the bag about a food product. The bag is particularly adapted for packaging whole turkeys and the like and, to this end, the heat seal is configured so the bag pocket closed end is a deep cavity shaped to accommodate the tail end of the turkey.

Description: Field of the Invention: The present invention relates generally to shrink bags as may be used for packaging food products and more specifically to a heat shrinkable bag having an integral carrying handle. Background of the Invention It is customary for food processors to vacuum package bulky food articles such as whole muscle meat products, brick cheese and poultry in shrink bags. The processor loads the food article into the bag and evacuates the bag to collapse it about the food product. The bag is sealed while in its evacuated condition by gathering the open end and applying a metal clip or by heat sealing. The sealed bag then is passed through a hot water bath or hot air tunnel to shrink the sealed bag about the food product. Shrinking the bag in this fashion closely conforms the bag to the contour of the food product thereby making an attractive, generally wrinkle-free package. Poultry items such as turkeys and other whole birds present several problems for this type of packaging. For example, the poultry carcass is generally the shape of a tear drop having a broad rounded breast portion tapering to the tail of the bird. The tear drop shape is accentuated by the customary practice of folding the legs of the bird close to the body and binding the end of the legs to the tail of the bird. This tear drop shape does not lend itself to formation of a substantially wrinkle free package even when using shrink film. A bag fabricated to accommodate a whole bird, generally has front and rear panels composed of a heat shrinkable plastic film which are heat sealed together at the closed end of the bag. It is common to have the closed end of the bag convex to accommodate the broad rounded breast of the bird. The opposite open end of the bag must be wide enough to receive the bird which is inserted breast first into the bag. If the wide bag opening is stretched to a flat width and heat sealed straight across the bag, a considerable amount of unfilled bag material remains extended across the tail of the bird. On heat shrinking, only a portion of this material conforms to the tapered contour of the bird whereas the remainder forms an unattractive flange which increases in width towards the tail of the bird. One approach for avoiding the formation of this flange is to gather the open end of the bag about the tail of the bird and close the gathered opening with a metal clip. This procedure pulls the bag close to and along the more tapered parts of the bird. Heat shrinking the pulled and gathered bag material generates creases and folds which radiate out from under the dip for some distance along the body of the bird. While this generally provides a more asthethically pleasing appearance than the flange caused by heat sealing, these creases and folds often truncate any design or identification printed on the bag and are objectionable. Accordingly, an even smoother, crease and fold-free appearance with the bag sketched taut over the legs and tail of the bird is preferred. Another problem related to packaging turkeys and the like in shrink bags is that the resulting packaged product is bulky, relatively heavy, usually frozen, and difficult to manually grasp and lift. Therefore it is desirable to provide a carrying handle to facilitate handling the vacuum packaged product. For this purpose a separate handle is attached to the packaged product at the clip closure or the product is inserted into a netting which is gathered and dipped to provide a carrying handle. Both arrangements add to the packaging costs. Preferably, the handle should be formed integral with the bag to avoid the added expense and processing steps of attaching a handle to the packaged product. For poultry packaging, a handle located at the tail of the bird is preferred as this leaves the package over the breast area of the bird free to receive printed information such as a decorative design, corporate logo or other identifying product information. Also, a handle at the tail of the bird provides a desirable weight distribution in that the heavier breast portion of the bird is carried below the lighter tail portion. GB-A-2 189 220 already discloses a flexible packaging container formed of shrinkable plastic film and comprising a product-enclosing space having a margin defined by a transverse heat seal, and film material between said heat seal margin and an edge of the container, with at least one hole having a closed periphery formed in the material between the edge of the margin, to define suspension means for a finished package formed from the container. In this container the at least one hole is disposed at the end of the container remote from the open end of the container through which the product is inserted. US-A-4 555 025 discloses a heat shrinkable bag comprising: front and rear panels of a thermoplastic heat shrinkable material defining the front and rear of a bag pocket, the panels being joined leak-tight along side edges and having common ends including a first end and an opposite end; and a continuous transverse heat seal connecting said front and rear panels adjacent to said first end, said heat seal defining the closed bottom of said bag pocket for containing an article to be packaged which is inserted into said bag through said opposite open end. This patent also discloses a method of making a shrink bag comprising: providing front and rear bag panels of a thermosetting heat sealable material in a layflat condition, said panels joined leak-tight along side edges to form a bag pocket and having common ends including a first end and an opposite end; and heat sealing said bag panels together adjacent to said first end thereby forming a continuous transverse heat seal which defines a leak-tight bag pocket closed bottom. The prior bag is a so called "extended lip bag" wherein one bag panel extends beyond the bag open end. As disdosed in this patent, a handle is formed in the extended lip portion by punching a hot die through the lip to provide an opening having a fused bead extending continuously about the opening. Formation of the opening in the lip is essential because inserting the hot die through the bag at any other location will fuse the bag panels together thereby partly occluding the bag. Upon heat shrinking, the extended lip thickens and forms a handle which protrudes longitudinally from the resulting package. Accordingly, an object of the present invention is to provide a shrink bag having an integral handle positioned so as not to occlude any portion of the bag opening. Yet another object of the present invention is to provide a shrink bag with an integral carrying handle wherein the bag is especially adapted for packaging whole body poultry such as turkeys and the like. A further object of the present invention is to provide a shrink bag having an integral handle portion located at the end of the bag opposite its open end. A still further object is to provide a shrink bag having an integral handle which lies close to the surface of the resulting package. Summary of the Invention Accordingly, the subject invention relates to a heat shrinkable bag as defined in claim 1 and a method of making a shrink bag as defined in claim 12. A shrink bag according to the present invention has an open end for loading a product into the bag and a closed end wherein a handle forming portion of the bag is adjacent the closed end. The bag of the present invention is particularly adapted for use in packaging whole body poultry such as turkeys and the like. For this reason the bag is described in reference to a preferred packaging use as a turkey or a whole body poultry bag. To facilitate its use as a turkey bag, the shrink bag of the present invention has a closed end formed to receive the tapered configuration of the tail portion of the bird. The closed end of the bag preferably is formed by heat sealing wherein the heat seal is generally concave across the bag to form a deep bag pocket for receiving the tapered tail end of the bird. A skirt portion extending from this heat seal contains a slit which forms a handle opening. Thus, the bag handle is formed from portion of the material of the skirt at the closed end of the bag and to a large extent is formed of the excess bag material heretofore pulled or gathered around the tail to prepare the bag for a clip closure. With this preferred arrangement the bird is loaded tail first through the bag opening. The bag is evacuated and then the bag opening is then closed, preferably by stretching it to a flat width and heat sealing around the breast of the bird. Closing the bag about the breast of the bird in this fashion requires significantly less gathering than if the bag is closed about the tail. On subsequent heat shrinking, the resulting flange of bag material around the breast of the bird is considerably reduced from the flange created when heat sealing straight across the bag at the tail end of the bird. Also, the bag is formed to accommodate the tapered, tear drop-shaped configuration of the tail end of the bird so the area of bag material subject to heat shrinking about the tail is reduced. The result, on heat shrinking, is a more aesthethically appealing package in that the bag material around the entire bird is smooth, taut and substantially wrinkle-free. Moreover, heat shrinking causes the skirt portion at the closed end of the bag to draw over the resulting package so the handle formed from the skirt lies close to the package surface. This produces a handle which is unobtrusive and yet is easily grasped for manually lifting the package. Description of the Drawings Fig. 1 is plan view of a bag according to the present invention unfilled and prior to heat shrinking; Figs. 2 and 3 are plan and elevation views respectively showing a package comprising the bag of Fig. 1 containing a whole body poultry and after heat shrinking; Fig. 4 shows the package of Fig. 2 in a carrying position; Figs. 5 to 8 are views similar to Fig. 1 only showing alternate bag embodiments; and Figures 9 and 10 are plan and elevation views respectively showing a package comprising the bag of Figure 7 containing a whole body poultry and after heat shrinking. Detailed Description of the Invention Referring to the drawings, Figure 1 shows a bag of the present invention generally indicated at 10 in its lay-flat condition prior to its packaging use. The bag is made of any suitable heat shrinkable thermoplastic packaging film commonly used for vacuum packaging food products. A suitable film is an oriented heat shrinkable film as disclosed for example in U.S. Patent No. 4,863,769. Generally, such films are formed as blown tubes. The tube is collapsed to a lay-flat condition to provide superimposed front and rear bag panels having seamless side edges. The laid-flat tube is then heat-sealed across its width to form a dosed bag end and then it is severed at a location spaced from the heat seal to provide an open bag end. In accordance with this practice, Figure 1 shows the bag 10 to have superimposed front and rear panels 12 and 14 respectively. The front and rear panels are congruent and lay flat one against the other. The panels are joined along lateral side edges 16, 18. If the bag is made of a collapsed tube as noted above, the side edges 16, 18 are seamless. Otherwise one or both side edges 16, 18 contain a seam such as is formed by heat sealing or an adhesive for connecting the panels. The congruent bag panels 12, 14 have common ends 20 and 22 wherein end 22 is the open end of the bag. The panels at end 20 are optionally connected such as by heat sealing the panels together. The front and rear panels 12, 14 are connected by a heat seal generally indicated at 24 which extends across the bag inboard of the end 20. This heat seal 24 defines the closed bottom of a bag pocket for containing an article to be packaged which is inserted into the bag through the open end 22. The sides of the bag pocket are formed by bag panels 12, 14. The heat seal 24 forming the bottom of a bag pocket may extend straight across the bag. Preferably the heat seal is shaped to conform generally with an end of an article to be inserted into the bag pocket and against the bottom of the bag. In one embodiment of the bag for use in packaging whole poultry, the heat seal provides a deep cavity shape able to accommodate the tapered configuration of the tail end of a bird such as a turkey or the like. In this respect, Figure 1 shows that the heat seal 24 has generally linear side portions 30, 32 which extend from each side edge 16, 18 respectively and angle inward toward the longitudinal axis of the bag in the direction away from the open end 22. These two side portions 30, 32 converge toward each other and merge with an arcuate transverse base portion 34 so there is a smooth continuous transition from one angled side portion 30, 32 to the other. The result is that the closed bottom of a bag pocket as defined by heat seal 24 provides a deep concave pocket able to accommodate the tail end portion of a turkey or the like when the bag is open from its lay-flat condition. The portion of the bag panels 12, 14 between heat seal 24 and end 20 defines a skirt 26 at the end of the bag opposite open end 22. The skirt includes the bag end 20 and contains a generally centrally oriented slit 28. The slit can be formed by any suitable means which cuts through both bag panels. Preferably the slit is formed by a hot knife which burns through the bag panels and in the process welds the panels together at the slit margins. As described hereinbelow, the slit forms an opening to facilitate use of the skirt as a bag handle for carrying an article sealed within the bag. The placement and configuration of the slit is important to a proper functioning of the skirt as a bag handle. For example, the ends 36, 38 of the slit should be angled towards the bag side edges 16, 18 in the direction of the bag opening 22. This will help to avoid stress concentrations at the end of the slit that might cause the skirt to tear when lifting an article sealed in the bag. The distance between the slit and the heat seal 24 in the region indicated at 23 must be sufficient to avoid the propagation of stress concentration into the heat seal 24 which might cause the heat seal to tear. Also, the distance between the slit and the end 20 of the bag in the region indicated at 25 must be sufficient to provide a handle to support the product packaged within the bag. The adjustment of these parameters to provide an appropriate configuration and location for the slit in order to provide a handle able to support the weight of the packaged product is well within the skill of the art. Figure 2 shows a package generally indicated at 41 formed using the bag of Figure 1. To this end a bird such as a turkey or the like is loaded tail first into the bag of Figure 1 through its open end 22. The tail portion of the bird generally fits and is received into the concave bottom of the bag pocket defined by heat seal 24. Next the bag is evacuated and the open end of the bag is stretched to a flat width and is sealed, preferably by a heat seal 40, as shown in Figure 2, around the breast portion of the bird. The sealed bag is then immersed in hot water or otherwise heated to shrink the bag about the bird (or other product) contained within the bag. On heat shrinking, the bag material becomes tight to the bird to provide a smooth generally wrinkle-free package. In this respect, wrinkles or other stretch lines at the tail end portion of the bird are eliminated since the deep cavity of the bag pocket provided by the contour of heat seal 24 conforms to the shape of the tail end portion. Thus, any printing on the bag is not obscured or truncated by creases and folds otherwise produced if the bag open end is gathered around the tail end of the bird. Also, on heat shrinking, the portion 25 (Figure 1) of the skirt material between the slit 28 and bag end 20 shrinks and pulls away from the slit. However, the shrink of the skirt material 23 between the slit and heat seal 24 is restrained somewhat by the product within the bag. The result as shown in Figure 2, is that the skirt portion 25 of Figure 1 shrinks inward towards heat seal 24 and draws over and across the bag pocket formed by the congruent panels 12, 14. As shown in Figures 2 and 3, this forms the skirt portion 25 of Figure 1, to a bag handle 42 which extends over and across the resulting bag package 41 adjacent the bottom of the bag pocket as defined by heat seal 24. The handle may extend and locate either over the top of the bag package 41 as shown in solid line (Figures 2 and 3) or it can extend and locate across the back of the package as shown in dotted line in Figure 3. If the skirt portion 25 does not initially shrink and draw to a desired location (front or back of package 41), it is easily stretched and pulled over the end of the package (now defined by heat seal 24) to a desired position (front or back). While the handle 42 lies close to the surface of the package, slit 28 provides sufficient clearance between the handle and the surface of the package 41 to permit the insertion of one's hand to grasp the handle. Subsequently, when the handle is gripped and the package lifted, the handle will stretch from the package as shown in Figure 4. However, prior to gripping and lifting, the handle is located substantially within the general perimeter of the package. This facilitates locating the handle when a plurality of the packages are heaped together as in a frozen foods case. The heat shrunk bag package 41 as shown in Figures 2-4 is preferred for poultry such as turkeys and the like. In this respect, the handle 42 is located at the tail of the bird which provides a desirable weight distribution when lifting and handling the bag package in that the heavier breast portion 44 is lowermost. Also, the broad area of the bag around the breast of the bird, as indicated at 44, is unobstructed and available for receiving printed matter. In the bag of Figure 1, the slit 28 is continuous from end-trend. As a result, the portion 25 of the skirt between the slit 28 and bag end 20 is unconnected and loose from the rest of the skirt and the bag. This loose, unconnected portion of the skirt can flip and flap about which may interfere with the automatic or manual handling of the bag. Accordingly, in order to maintain this skirt portion 25 associated with the bag, Figure 5 shows another embodiment having the bag handle forming slit in the form of perforations 50. These perforations weaken the connection of the skirt portion 25 to the bag but maintains a connection so the skirt portion 25 remains associated with the bag. Preferably, the spacing of the perforations 50 is such that upon heat shrinking, the shrink induced stresses are sufficient to separate the skirt portion 25 by tearing along the line of the perforations. Otherwise, the separation can be accomplished by manually tearing along the line of perforations. To insure that any tear propagation does not exceed the line of the perforations 50, Figure 5 shows a heat seal 52 which connects the front and rear panels 12, 14 and circumscribes the line of perforations 50. As an alternative, the heat seal 52 adjoining the front and rear panels can have a width sufficient to accommodate the line of perforations 50 so these perforations are made in the heat sealed material. For retail purposes, it often is desirable to attach a tag to the bagged produce on which is written the weight, cost or other relevant information regarding the product. Generally, this tag is attached after packaging. However, in another embodiment of the present invention provision is made for the attachment of a tag during the bag manufacturing process. Figure 6 shows one embodiment wherein a tag 54 is attached to the bag pocket forming heat seal 24. The tag preferably is of a heat sealable plastic film which has little or no heat shrink properties. This allows the entire area of the as-attached tag to be used for later-applied information such as the weight and price of the product contained in the shrink bag package. A suitable plastic film for this purpose has been found to be a sheet of spun bonded linear polyethylene fiber as sold by DuPont under the brand name TYVEK. Preferably, the tag should be oriented so it overlaps a bag pocket forming portion of the front and rear panels 12, 14 and does not overlay the skirt portion 26. This is to avoid mistaking the tag for a handle because it is possible that if a bag containing a turkey is lifted by the tag the tag could tear out and break open the sealed package. The tag 54 also can be located at the terminal end 20 of the bag in cases where this end is formed by heat sealing as shown in Figure 7. In Figure 7, a second heat seal 56 longitudinally spaced and generally parallel to heat seal 24 defines the end 20 of the bag and the tag 54 is attached to the bag by this second heat seal. As shown in Figure 7, the tag 54 is positioned near a lateral side edge of the bag to minimize the possibility of mistaking the tag for a handle. Figure 8 illustrates another embodiment of the invention wherein the closed bottom of the bag pocket is formed by a heat seal 58 which is curved across the bag. This shape accommodates the rounded breast portion of a turkey or the like inserted breast first through the open bag end (not shown) opposite bottom 58. Adjacent the curved heat seal 58 is a skirt 126 formed by the portion of the congruent front and rear panels 112, 114 which extend from the heat seal to the end 120 of the bag. Skirt has a slit 128 which forms a bag handle opening. This slit is arcuate so it extends generally parallel with the heat seal 58 wherein the end portions 136, 138 of the slit are angled towards the lateral edges 116, 118 respectively. This shape acts to relieve stress concentrations at the ends of the slit so as to reduce the likelihood of tearing when lifting a heat shrunk bag containing a heavy bird or another food product.

Claims: A heat shrinkable bag for packaging bulky food articles, comprising: (a) front and rear panels (12, 14, 112, 114) of a thermoplastic heat shrinkable material defining the front and rear of a bag pocket, the panels being joined leak-tight along side edges (16, 18, 116, 118) and having common ends including a first end (20, 120) and an opposite open end (22); and (b) a continuous transverse heat seal (24, 58) connecting said front and rear panels (12, 14, 112, 114) adjacent to said first end (20, 120), said heat seal (24, 58) defining the closed bottom of said bag pocket for containing an article to be packaged which is inserted into said bag through said opposite open end (22), said transverse heat seal (24, 58) being spaced from said first end (20, 120); and (c) a skirt (26, 126) defined by said front and rear panels (12, 14, 112, 114) between said first end (20, 120) and said heat seal (24, 58) at the closed bottom of said bag pocket opposite said open end (22), said skirt (26, 126) having a transverse slit (28, 50, 128) opening through said panels (12, 14, 112, 114) and including a portion between said slit and said first end (20, 120) which upon evacuation, sealing and heat shrinking said bag (10) containing a said article forms a handle portion (42, 142) for gripping and carrying said article containing bag (10); wherein: (d) said heat seal (24,58) extends in an arc across said bag (10) to provide said bag pocket with a generally concave closed bottom; (e) said slit (28, 50, 128) is generally arcuate and parallel to said heat seal (24, 58); (f) said slit (28, 50, 128) has end portions (36, 38, 136, 138) extending at diverging angles toward each side edge (16, 18, 116, 118) of said bag (10) in the direction of said open end (22) to minimize stress concentrations at said slit and portions when lifting said bag after sealing an article within said bag pocket; and (g) wherein a skirt portion (25, 125) between said slit (28, 50, 128) and said first end (20, 120), upon heat shrinking said bag (10) containing a said article, draws towards said transverse heat seal (24, 58) and forms a bag handle (42, 142) extending overand across said bag pocket A heat shrinkable bag as in claim 1 having a second transverse heat seal (56) connecting said panels (12, 14) at said first end (20). A heat shrinkable bag as in claim 2 including a tag (54) of heat sealable, non-heat shrinkable material attached to said bag at said first end (20) by said second heat seal (56). A heat shrinkable bag as in any one of claims 1 or 2 including a tag (54) of heat sealable, non-heat shrinkable material attached to said bag (10) by said transverse heat seal (24). A heat shrinkable bag as in any one of the preceding claims wherein said side edges (16, 18, 116, 118) are seamless. A heat shrinkable bag as in any one of claims 1 to 4 wherein said side edges are heat seals connecting said front and rear panels. A heat shrinkable bag as in any one of the preceding claims wherein said first heat seal (24) includes: (a) linear side portions (30, 32) angled inward from each panel side edge (16, 18) in a direction away from said open end (22); and (b) an arcuate transverse base portion (34) forming a smooth transition from one angled side portion to another such that said heat seal (24) provides said bag pocket with a concave closed bottom adapted to receive the tapered tail and leg portions of a whole body poultry inserted tail first through said open end (22). A heat shrinkable bag as in claim 7 wherein said slit (28) has end portions (36, 38) angled generally in the same direction as said heat seal linear side portions (30, 32). A heat shrinkable bag as in any one of the preceding claims wherein said slit comprises a plurality of spaced perforations (50). A heat shrinkable bag as in claim 9 wherein said panels (12, 14) are heat sealed together in an area adjacent and extending about said slit. A heat shrinkable bag as in claim 1 wherein (a) said first end (20) is closed; (b) said closed end (20) is formed by said inboard heat seal (24) and an outboard heat seal (56) longitudinally spaced therefrom, both said heat seals (24, 56) connecting said bag panels (12, 14) and extending transverse said panels from one lateral side edge (16) to another (18); (c) said inboard heat seal (24) forming a generally concave pocket contoured to receive the generally tapered tail and leg portions of a whole poultry body inserted tail first through said open end (22); (d) said outboard heat seal (56) cooperating with said inboard heat seal (24) in defining said skirt (26) at the end of said bag (10) opposite said open end (22); and (e) a portion (25) of said skirt (26) between said handle-forming slit (28) and said outboard heat seal (56) drawing towards said inboard heat seal (24) and locating over said bag pocket responsive to heat shrinking said bag about a whole body poultry sealed in said bag pocket thereby providing said handle (42). A method of making a shrink bag comprising: (a) providing front and rear bag panels (12, 14, 112, 114) of a thermosetting heat sealable material in a lay-flat condition, said panels joined leak-tight along side edges (16, 18, 116, 118) to form a bag pocket and having common ends including a first end (20, 120) and an opposite end (22); (b) heat sealing said bag panels (12, 14, 112, 114) together adjacent to and spaced from said first end (20, 120) said first end (20, 120) thereby forming a continuous transverse heat seal (24, 58) which defines a leak-tight bag pocket closed bottom and which extends in an arc across said bag (10) to provide said bag pocket with a generally concave closed bottom; and (c) cutting through the portion of said panels (12, 14, 112, 114) between said leak-tight bag pocket closed bottom, a transverse slit (28, 50, 128) which is generally arcuate and parallel to said heat seal (24, 58) and which has end portions (36, 38, 136, 138) extending at diverging angles toward each side edge (16, 18, 116, 118) of the bag (10) in the direction of said open end (22) to minimize stress concentration at said slit end portions when lifting the bag after sealing an article within said bag pocket; and said first end (20, 120) and said slit (28, 50, 128) defining a skirt portion (25, 125) which upon heat shrinking said bag (10) about a product sealed in leak-tight fashion in said bag draws towards said transverse heat seal, forming an integral bag handle (42, 142) opening adjacent said bag pocket bottom end and extending over and across said bag pocket. A method as in claim 12 wherein said heat sealing provides a leak-tight bag pocket closed bottom end having: (a) linear side portions (30, 32) angled inward from each panel side edge (16, 18) in a direction away from said open end (22); and (b) an arcuate transverse base portion (34) forming a smooth transition from one angled portion to another whereby said heat sealing provides said bag (10) with a relatively deep concave bag pocket upon opening said panels (12, 14) from said lay flat position. A method as in claim 12 or 13 including connecting said panels (12, 14) at said first end (20) by heat sealing along a transverse line extending generally parallel to said bag pocket closed bottom. A poultry containing package (41) characterised by using a heat shrinkable bag according to any of claims 1-11.

Inventors: KUPCIKEVICIUS VYTAUTAS, KUPCIKEVICIUS, VYTAUTAS
Applicants: VISKASE CORP, VISKASE CORPORATION
Application year: 1991
Main classification: B65D75
IPC codes: B31B19, B65D75, B65B25