CA1200232A

CA1200232A - Hang bag

Info

Publication number: CA1200232A
Application number: CA000413746A
Authority: CA
Inventors: Garnet J. Kent; John C. Wood
Original assignee: WR Grace and Co
Current assignee: Cryovac LLC
Priority date: 1982-03-15
Filing date: 1982-10-19
Publication date: 1986-02-04
Also published as: JPS58171346A; JPH0436941B2; DE8224353U1; NZ203578A; AU1247283A; AU557279B2

Abstract

HANG BAG
ABSTRACT OF THE DISCLOSURE
This invention is a hang bag and the method for making it. The hang bag is designed to be hung on peg board displays at supermarkets and the bag comprises a non-shrinkable, heat seal-able strap across the width of a side seal heat shrinkable bag.
After the product has been put in the bag and the bag has been shrunk, the unshrunken strap forms a convenient loop for easy hanging.

Description

~3 _ ~2(:~)Z3~

FIELD OF THE INVENTION

This invention relates to thermoplastic bags which may be filled and hung from a peg board display in a supermarket. More partic-ularly, the invention relates to side-seal thermoplastic bags which are heat shrinkable and are used to package processed meat and cheeses which are displayed for retail sale.

BACKGROUND OF THE INVEN~ION

In retail grocery stores and supermarkets many of the processed meat and cheese packages are hung on peg boards for better display for the customer. In order to provide a hang up feature there are a number of alterr~atives to consider. Straps or hooks could be used which could be fixed to the finishecl package in a retail stores, e.g., a strip of semi-rigid plastic with a hook on one end; or, cut-outs of paper which can be shaped into a cone or a strap to hold a filled bag may be llsed. Another . type of hang up feature consists of punching holes at either end of the bag and reinforcing the hole with metal or plastic eyelets in order to provide a suffic~iently strong hanging means. Still another type of feature is a loop or strap sealed to a bag at the time the bag is macle.
It is this last feature with which this invention is concerned.
In United States Patent No. 3,207,300 which issued on September 21, 1965 to H. L. Farmer, a labeled package is shown which contains -semi-rigid articles with a wrapper of heat-sealable and heat-shrinkable plastics film surrounding the articles and a printed label strip of narrow width heat-sealal)le and shrinkable plastic film is disposed within the wrapper and extendl~ transversely of the articles with the opposite ends of the strip respectively secured within heat seals. However, the strip shrinks with the wrapping and a ]oop is not leEt so that a hang strap is formed. Accordingly, it is one object of the present invention to provide a ]Dackage with a shrinkable wrapper and a non-shrunk strip or strap which can be used as a hanging feature.

Y141B2/b ~k z For packaging many food products, especially fresh meats or processed meats it is quite deslrable to use a wrapping material which has low oxygen permeability. One such material is described in United St~tes Patent No. 3,741,253 which issued to H. J. Brax et al on June 26, 1973. In the Brax et al patent a packaging film having a first layer of a crosslinked ethylene vinyl acetate copolymer is described which is extrusion coated with a layer of a vinylidene ch]oride copolymer which in turn is extruslon coated with another layer of ethylene vinyl acetate copolymer. [n using a bag which is made from Film according -to the Brax et al patent if the strap is sealed to the non-crosslinked vinyl aceta-te polymer layer, it was found that grease would attack the strap seals and the seal would fail at either instantly or either a short time af-ter a filled bag was hung by the strap. Accordingly, it is another object of the present invention to provide a hang bag which is useable with a grease containing product and which will hang at retail display for an extended period of time.
The oregoing and other objects will be better understood with reference to the summary of the invention, the drawings, and the detailed description which follows.
SUMMARY OF THE INVENI'ION
In one aspect, the present invention is a hang bag com-prising:
(a) a bag portion including:
(i) fron-t and back panels of heat shrinkable, thermoplastics sheet ma-terial;
(ii) said panels comprising a single sheet folded so that the fold comprises the bottom of the bag and, (iii) each side of said fron-t and back panels being sealed to the corresponding si.de of the panels along their side edges in parallel slde seals leaving the top side unsealed thereb~
defining the mouth of the bag for loading a product into the bag;
and, (b) a single strap of non~heat shrinkable, thermo plastics sealable materlal, one end of said strap bei.ng sealed to one side seal and the other end to the other side seal;
(c) a heat shrinkable strap each end of which is sealed in an opposi.te side seal of said bag, said heat shrinkable strap being shrunken with said bag, said non-heat shrinkable strap being superimposed over said shrinkable strap thus providing a hang loop for said bag, the respective ends of sai.d non-shrinkable strap and said shrinkable s-trap being sealed together at a side seal, whereby when said bag is heated and shrunk the heat shrinkable strap shrinks with the bag and remains in contac-t therewith, said shrinkable bag and strap shrinking away from the non-shrinkable strap which remains unshrunken and provides a hang loop.
DESCRIPTION OF THE DR~WINGS
The invention may be better understood with reference to the accompanying drawings in which:

_D~_ Figure I is a scl~ematic representation of the process of tubing and strap material being made into a side-seal hang bag;
Figure 2 is a perspective representation of unfilled, unshrunk hang bag according to the present invention;
Figure 3 is a representation of a filled and shrunken bag according to the present irlvention showing the unshrunk hang loop; and, Figure 4 is a representation of packages according to the present invention being displayed on a peg board at a retail supermarket.

DETAlLED DESCRIPrlON

Turning now to Fig~re 1, roll 1 of f]attened tubing 2 is shown being guided over guide roll 3 and through sealing and perforating means 4. The flatteDed tubing is preferably made from multi-layer, thermo-plastic film having low oxygen permeability and one such fi].m is described in the above mentioned Brax et al patent. Another preferred film is one in which a substrate ]ayer of ethy]ene vinyl acetate co-polymer containing approximately 9% vinyl acetate is extruded and cross-linked by irradiation and is subsequently extrusion coated witb two coextruded layers. The two coextruded layers being molten and being extruded onto the substrate at the same time is, in effect, very much the same as extrusion coating with one layer. The two coextruded layers that make up the extrusion coating are a vinylidene chloride copolymer layer of the type disclosed in the Brax et al patent and a layer o~ ethylene vinyl acetate copolymer having approximately 9% vinyl acetate. The vinylidene chloride copolymer layer contacts the substrate and the ethylene vinyl acetate copolymer layer is on the outside. Thus, again considering Figure 1, the outside surface Or the flattened tubing 2 compri.se uncrosslinked ethylene vinyl acetate copolymer and the inner surfaces of the tubing whi.ch are in contact with each other comprise crosslinked ethylene vinyl acetate copolymer. This tubing is preferably slit at the side edge opposite that where strip 8 is being applied from roll 7 and the slit edge, of course, will provide the mouth or opening to the comp]eted bag. Slitting apparatus are well known in the art and are not shown.

Y]4LB5/b

2~
As the slit tllbing en~ers the sealing appara~us the strip of strap material 8 has been laid on top of the tubing. This strap material ~ is preferably made from low density polyethylene or from ethylene vinyl acetate copolymer and has not been oriented or stretched to render it heat-shrinkable to any appreciable extent. It must, of course, be a therrnop]astic material which is heat-sea]ab]e and can be sealed with the tubing materia] in the sealing means 4. A ~ypical width of this strap material is 25mm. or about one inch.
The w;dth oE the f]atteDed ~ubing will vary according to the product to be packaged in the .Einished s:ide seal bag but a typical width of the flattened tubing is 10 to 12 inches or 25 to 30 centimeters.
The sea]ing means 4 can be any commercial seal and sever apparatus. These are well knowll in the art and ~ypically would comprise an electrically resistant wire which when given a pulse of e]ectric current wi]l be hea~ed to a sealing temperature as the opposed members of sealing means 4 press together upon the tubing through strap 7. The sea]ing means 4 actually has two sealing wires to forrn spaced apart seals and, in addltion, ~he sealing means has perforation means to punch perforations 6 into the flattened tubing 2 and strap ~. The perforations are typically 2~2 to 3" apart and the dwell time when the sealing members close to form the side seals wi]l be in the order of ~ to '~ second. In Figure 1 after the sealing and perforating has been accomp]ished a flattened side seal bag 9 results which is still attached to the trailing bags which are being made by the sealing means 4. A side seal bag is genera]ly considered to be one in which at least one side is closed by a seal and the bottom is formed by a fold.
Turning to Figure 2, bag 9 has now been separated from the tubing and is ready to be filled. Filling can be manual or can be accomplished by any number of means, and a great variety of products, particu]arly food products such as meat and cheese can be inserted in the mouth of the bag which is at the end opposite strap ~. In the typical example being described herein, a 500 gram chub of process meat such as sausage is placed in the bag, the bag evacuated by any number o-f means well known in the art such as vacuum chamber means or vacuum nozz]e means and the mollth of the bag is heat sea]ed. One suitable machine is the ~714LB6/b 6 ~Q~ 3~Z
Model 8200 rotary V8C~JU~II m~c~line sold by ~he Cryovac Division of W. R.
Grace & Co. of Duncan, South Carolina, ~.S.A. A heat seal similar to that applied by the impulse sealing means 4 can be used or a metal clip can be applied. After the final closure seal has been applied, the filled bag is placed briefly in water heated in ~he range of 185 to 205~F to shrink the unsealed bag 9 tightly around ~le meat chllb so that the package has the appearance shown in Figure 3 where tlle bag 9 has shrunk and the strap material 8 has not thereby leaving loop 8 for hanging purposes.
In Figure 4 a display pegboard 10 common to many superrnarkets is showrl having a peg 11 from which filled bags or packages 9 are hung by loop 8.
It was discovered that when a single layer strap was applied to multi-]ayer bag material which had not been coextruded that grease from the packaged product would attack the strap seals at elevated temper-atures, such as the heat shrink temperature, and would cause the ouLer ply of the bag to delaminate.
It was surprisingly discovered that the delamination prob1em could be solved by coextruding at least two other layers of the mu]ti-layer film from which the bag is made, one of these layers being the layer to which the ends of the strap 8 are heat sealed.
In a test to determine the reliability of the hang loop of this invention, peanut oil was applied to the inside of bags before packaging meat and then the bag was hung by the loop at 32C. The non coextruded bag structures were found to fail either instantly or only after a very short time when subjected -to this test with a 500 gram product. On the other hand, bags with the coextruded structure containing 500 grams of meat chub therein were hung from the strap both at chiller temperatures (8~C) and at room temperature. No failures were discovered in hanging trials lasting up to 30 days.
In addition to discovering that the coextruded structure surprisingly solved the strap failure problem it was found that if a relatively wide band, approximately 2" wide, of heat shrinkable film such as heat shrinkable polyetnylene was applied to one side of the tubing and then the unshrinkable strap was sealed on top of the shrinkable film that a successful hang bag would result. It was theorized that the wide band Y14LB7/b 7 ~ i z~
of shrinkable film which shrinks ~ith t.}l' tubirlg from which the bag is made distributes the forces in the s~rap over a longer ]ength of the outer ply of the bag material. This type of construction can be made as shown in ~igure 1 by applyiDg a two layer s~rip of strap material 8 from a roll 7 wherein the first layer is a t.hern)oplastic heat shrinkable material and ~he second layer superi.mposed over the first is a non-shrinl;-able material which will be the hang loop. As described herein above the two layèr strap màterial 8 would be applièd in the same fash:ion as the single layer but wilen shrunk the shrinkable ply or ]ayer shri.nks ~itll ttle bag materi.al and the non shrinkàble material dc,es not thus formirlg tile hang loop as bèfore. The width of the hang loop will be about 25mtn as before and the width of the shrinkable film wil~ be about 2 :inclles or about 5 cm.
As menti.oned above, one of the prirlciF)al objec-s of the preseilt invention is to provide a hang bag in which the material is both heat shrinkable and is one which has low gas pel-rlleability. Hydro]yzed ethylene-vinyl acetate copolymer when used as a ]ayer in a multi-~yer film provides excèllent resistance to gas transmission, and, in the BraA
et al patent it is stated that vinylidene chloride copolymers provide excellent resistance to the transmission of oxygen and other gases but that monolayer films of vinylidene chloride copolymers do not have the abuse resistance necessary to stand up to col~)ercial distribution practices. Thus, the Brax et al patent disc~oses the discovery of a multi-layer film which includes a layer of vinylidene chloride copolymer in a unique combination of heat shrinkable, abuse resistant materials;
and, in the present invention, it is desirable to use such a multi-layer film as disclosed in Brax et al, but the application of strap material to such a multi-layer film in a high speed bagmaking process resulted i.n an unacceptable failure rate when products containing grease were packaged in the bags and shrullk at elevated temperatures. The solution to this problem, which can be expected to occur in other multi-layer films used to package grease containing foods, e.g., fresh meat, smoked, cured and process meats and cheese, has been described above and is summarized in the claims below in which:

Y14LB8/b

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A hang bag comprising:
(a) a bag portion including:
(i) front and back panels of heat shrinkable, thermoplastics sheet material;
(ii) said panels comprising a single sheet folded so that the fold comprises the bottom of the bag and, (iii) each side of said front and back panels being sealed to the corresponding side of the panels along their side edges in parallel side seals leaving the top side unsealed thereby defining the mouth of the bag for loading a product into the bag;
and, (b) a single strap of non-heat shrinkable, thermoplastics sealable material, one end of said strap being sealed to one side seal and the other end to the other side seal;
(c) a heat shrinkable strap each end of which is sealed in an opposite side seal of said bag, said heat shrinkable strap being shrunken with said bag, said non-heat shrinkable strap being superimposed over said shrinkable strap thus providing a hang loop for said bag, the respective ends of said non-shrinkable strap and said shrinkable strap being sealed together at a side seal, where-by when said bag is heated and shrunk the heat shrinkable strap shrinks with the bag and remains in contact therewith, said shrink-able bag and strap shrinking away from the non-shrinkable strap which remains unshrunken and provides a hang loop.

*

2. The hang bag of claim 1 wherein said heat shrinkable, thermoplastics sheet material comprises three layers, the layer forming the inside surface of the bag being a crosslinked ethylene vinyl acetate copolymer, the middle layer being a vinylidene chloride copolymer, and the outside layer being an ethylene vinyl acetate copolymer, said middle and outside layers having been coextruded onto said inside layer.

3. The hang bag of claim 1 or claim 2 wherein said strap is positioned adjacent the bottom of the bag.

4. A package for a hanging display comprising:
(a) a food product selected from the group consisting of fresh meat, smoked, cured and processed meats, and cheese;
(b) a hanging bag in accordance with claim 1 shrunken about said product, said single strap of non-heat shrinkable thermoplastics sealing material constituting a hang loop for said package.