CA1222485A - Easy open bag having rupture strip - Google Patents
Easy open bag having rupture stripInfo
- Publication number
- CA1222485A CA1222485A CA000433778A CA433778A CA1222485A CA 1222485 A CA1222485 A CA 1222485A CA 000433778 A CA000433778 A CA 000433778A CA 433778 A CA433778 A CA 433778A CA 1222485 A CA1222485 A CA 1222485A
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- Canada
- Prior art keywords
- bag
- strip
- package
- film
- heat seal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
EASY OPEN BAG HAVING RUPTURE STRIP
ABSTRACT OF THE DISCLOSURE
An easy open package is provided that comprises a side-sealed bag of multiply thermoplastic film having inside and outside plies char-acterized in that inside-to-inside ply heat seal strength is greater than inside-to-outside ply heat seal strength; and a rupture strip of film, being the same material as the film of said bag, interposed between the surfaces of the mouth of said bag, said bag mouth being heat sealed through said strip forming one inside-to-inside type heat seal and at least one inside-to-outside type heat seal. Preferably, said easy open package further includes a reclosure element, and the inside ply of the film of said package is irradiatively cross-linked. An associated method for making said package is also provided.
ABSTRACT OF THE DISCLOSURE
An easy open package is provided that comprises a side-sealed bag of multiply thermoplastic film having inside and outside plies char-acterized in that inside-to-inside ply heat seal strength is greater than inside-to-outside ply heat seal strength; and a rupture strip of film, being the same material as the film of said bag, interposed between the surfaces of the mouth of said bag, said bag mouth being heat sealed through said strip forming one inside-to-inside type heat seal and at least one inside-to-outside type heat seal. Preferably, said easy open package further includes a reclosure element, and the inside ply of the film of said package is irradiatively cross-linked. An associated method for making said package is also provided.
Description
24~5 ~ACKGROUND OF THE INVEN~ION
This invention rela~es generally to a thermoplastic package of a composite film which, when heat sealed about an article, is easily openable. More particularly, this invention relates to an easy open bag having an easy-open rupture element which is heat sealed in the 00uth of said bag.
Cheese, iuncheon meat, and other products are frequently pack-aged in bags of thermoplastic film wrapped about the product and heat sealed to itself forming closure seams. In many cases, it is a problem to open the package without destroying the package thereby leaving it unsuitable for convenient reclosure. The problem is compounded because ~he films for packaging such products as cheese and luncheon meat should be strong and abuse resistant and have desirable gas transmission prop-erties, yet at the same time be capable of being opened without destroy-ing the package. Thus, it is a principal object of this invention to provide a closure and seal configuration which is easily opened by a relatively small opening force so as not to destroy the package.
Numerous packaging configurations have been proposed in the past which employ easy open features. ~or example, U.S. Patent 3,655,503 issued April 11, 1972 to Stanley et al shows a package closure seal wherein multilayer films are sealed together, which when pulled apart to open the package rupture and delaminate only in the seal area. U.S.
Patent No. 3,536,501 issued October 27, 1970 to Work shows a package in which the edge of its closure flap is folded over so that the outer film layer is sealed to itself. U.S. Patent 3,471,005 issued October 7, 1969 to Sexstone shows a pouch with its front panel folded inwardly at the pouch mouth and sealed to the rear panel of the pouch. U.S. Patent 3,460,742 issued August 12, 1969 to Langdon shows a package with its bottom left open for receiving an article and subsequent sealing and with Y]~LL2/sb its mouth-end formed with sealed tabs which are readily peeled open to expose the contained article for removal.
An associated problem encountered in easy open packaging is that of providing means for reclosure, for e~ample when it is desirable that the opened package be effectively reclosed to protect any unused portion of the package contents. Numerous reclosure elements have been proposed in the prior art, including those disclosed in U.S. Patents 4,117,934 issued October 3, 1978; 4,126,085 issued November 21, 1978;
4,174,597 issued November 20, 1979; and 4,138,932 issued February 13, 1979, all to Mowli et al and which deal with "twist tie" elements having dead~fold characteristics, i.e. once bend or folded the element remains in its bent shape and does not spring back or tend to return to its original shape thereby retaining the reclosure.
S~nYARY O~ THE INVENTION
The present invention provides a bag of thermoplastic film that is easily openable at a peelable heat seal along a rupture strip in the bag mouth, optionally having a reclosure element, and being especially adapted for packages made from multiply film in which inner ply heat seals are of relatively high strength, for example where the irlner ply is irradiatively cross-linked but the outer ply is not. The invention is especially suited for continuous manufacturing processes wherein a sepa-rable series of packaging bags is continuously produced. The invention obviates any need to turn inward a bag panel edge in the vicinity of the mouth seal to attain easy openability.
In the article aspects of the invention, there is provided an easy open package comprising a side-sealed bag of multiply thermoplastic film having inside and outside plies characterized in that inside-to-Y18LL3/sb 8~
inside ply heat seal s~rength is greater than inside-to-outside ply heat seal strength; and a rupture strip of film, being the same material as the film of said bag, interposed between the surfaces of the mouth of said bag, said bag mouth being heat sealed throug~ said strip forming one inside-to-inside type heat seal and at least one inside-to-outside type heat seal. Preferably, the inside ply of said film is irradlatively cross-linked, while the outside ply is not.
In one mode, the rupture strip is sealed in the package mouth in a folded configuration. In another mode, the rupture strip is not folded, but rather is flatly configured in the mouth seal. Optionally, the rupture strip may extend through the side-seals of the bag. Prefer-ab~y, said easy open pachage further includes a reclosure element.
In the method aspects of the invention, there is provided a method from making an easy open bag comprising providing for the panels of said bag two opposingly facing sheets of a multiply thermoplastic film having inside and outside plies characterized in that inside-to-inside ply heat seal strength is greater than inside-to-outside ply heat seal strength; interposing a rupture strip of film, ~eing the same material as the film of said bag, between said sheets toward and substantially par-allel to a transverse edge of said sheet pair; forming side heat seals across said sheet pair being transverse said strip direction and spaced equal to the interior width of said bag; and then forming a bag mouth heat seal along said strip such that there is one inside-to-inside type heat seal and at least one inside-to-outside type heat seal within said mouth seal.
Y18LL4/sb --3 ~
BRIEF DESCRIPT[ON OF THE DRAWINGS
Further details are given below with reference to the embodi-ments shown in the drawings wherein:
FIG. 1 is a front view of a side-sealed bag of the invention having a rupture strip sealed in the mouth of the bag;
FIG. 2 is a vertical cross-section through the bag mouth in FIG. l;
FIG. 3 is similar to FIG. 1 except that a rupture strip sealed in the mouth of a side-sealed bag extends transversely through the side-seals;
FIG. 4 shows an alternative embodiment in cross-section similar to FIG. 2 except that a rupture strip sealed in the mouth of a bag is folded downwardly over a reclosure element;
FIG. 5 schematically depicts a method for making the embodiment shown in FIG. 4, further in which the folded rupture strip and reclosure element extend through the side-seals of the bag as in FIG. 3; and FIG. 6 depicts a variant rnethod for making the embodiment shown in FIG. 1, in which the rupture strip and reclosure element do not extend through the side-seals of the bag.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring specifically to the drawings, in FIG. 1 there is shown a preferred embodiment 10 of the invention which is a side-sealed bag shown in the frontal view having a rupture strip sealed in the mouth of the bag which permits easy opening by an ultimate user to remove a con~ained product. The bag has front and rear panels, 11 and 12 respec-tively, of conventional thermoplastic packaging film joined by side heat seals 13a,b. The front and rear panels are dimensioned longitudinally such that there is an extended lip 14 at the mouth end of the bag and Y18LL5/sb ~ZZ ~5 an extended lip 15 at the bottom end of the bag. The mouth end o~ the bag is transversely heat sealed at 16. The bottom end of the bag is left ~ f open so that a product may be initially loaded into the bag, after which the bag bottom is heat sealed. The bottom extended lip 15 facilitates opening for initially loading the product into the bag. The extended lip 14 at the mouth end of the bag facilitates opening of the bag by the ultimate user to remove the product from the bag. In accordance with the invention, there is a rupture strip 17 inserted in the mouth of the bag between the front and rear bag panels and being sealed in the mouth seal 16. Rupture strip 17, in this embodiment, lies between side-seals 13a,b.
Reclosure element 18, such as a twist-tie, is adhered to the rupture i strip, being generally coextensive therewith and lying above the mouth seal. Thus, in use a producer inserts a product in the bottom of the bag by separating front panels 11 and 12 using bottom extended lip 15 and then transversely heat seals the bottom of the bag. The packaged article ! eventually passes to the ultimate user who opens the mouth end of the bag by first separating front and rear panels 11 and 12 utilizing extended .
lip 14 and then puliing outwardly to rupture that part of mouth seal 16 that is coextensive with rupture strip 17. This selected rupture mode is a key aspect of the invetion and is further discussed below. The contents of the package may then be partially removed, if desired, and the bag reclosed by rolling down the top of the bag and crimping reclosure element 18, being a conventional dead-fold reclosure element, i.e. once crimped does not substantially spring back.
A ke-y element of the invention concerns the type of film from which the bag and rupture strip are made. The rupture strip and the bag panels are of the same film. The film is characterized generally in that the inner and outer surface plies have differing heat sealing character-istics such that an inside-to-inside ply heat seal is substantially Y18LL6/sb _ ~ _ ~2 ~5 stronger than an inside-~o-outside ply heat seal (or an outside-to-outside heat seal). This situation arises when, for example, the inside ply is irradiatively cross-linked but not the outside ply. Representatively, such a film is disclosed in U.S. Patent 3,741,253 issued June 26, 1973 to Brax et al for "Laminates of Ethylene Vinylacetate Polymers and Polymers of Vinylidene Chlorlde" directed to a multiply packaging film having an inner layer of cross-linked ethylene vinylacetate polymer~ a directly joined middle layer of vinylidene chloride polymer, and an outer layer directly joined to the middle layer of an ethylene-vinylacetate polymer.
Such films of differing surface ply characteristics come about frequently due to processing limitations. For example, the inner ply is first hot blown as a tubular extrudate and then irradiatively cross-linked to enhance strength of the film and to enhance shrink capacity. Then a middle barrier layer and an outer abuse layer are extrusion coated onto this irradiatively crosslinked substrate to build up a barrier shrink film. Irradiative treatement is conducted prior to addition of the barrier ply since such treatment frequently has adverse effects on conven-Scl~a~ c~cle~allk) tional barrier material, particularly ~ ~.
In FIG. 2 there is shown a cross-sectional view taken along line 2-2 in FIG. 1 through the mouth of bag 10. Thus, there are shown front and rear panels 11 and 12 respectively, with rupture strip 17 interposed between them with its lower portion sealed in mouth seal 16.
Reclosure element 18 is shown affixed near the top of-rupture strip 17 being generally above mouth seal 16. The exemplary thermoplastic film as sho~n is a three-ply film having outer layer 25 serving as an abuse layer covering a middle barrier layer 26 which in turn is over a shrink layer 27. Front panel 11, rear panel 12, and rupture strip 17 are all of the same type film. As discussed above, the interior shrink layer 27 is ~]8LL7/sb - ~o irradiatively cross-linked, while outer abuse layer 25, which representa-tively is of ~he same composition, is not irradiatively cross-linked due to processing limitations discussed above. Thus, the inside-to-inside ply heat seal at 28 is substantially stronger than the inside-to-outside ply heat seal 23. Representative materials which can be suitably used in the invention are polyethylene and ethylene-vinyl acetate copol~mers in general for the material for the outer layer; materials selected from the group consisting of nylon, vinylidene chloride copolymers, propylene homopolymers and copolymers are suitable for the interior; and, cross-linked polye~hylene and ethylene-vinyl acetate copolymers are suitable for the inner layer.
To open the easy-open package, a user opposingly grabs the upper edges of front panel 11 and rear panel 12 respectively and pulls outwardly. The top of rupture strip 17 is spaced below the top of the bag as indicated at 19 so that rupture strip 17 is not likely grabbed along with either the front or rear panel during opening. It is believed that the most likely mode of rupture of the easy open seal is as indi-cated along dashed line 30 with rupture initiating at dashed line segment 30a near the top oE the mouth heat seal 16 at the inside-to-outside seal 29, then with rupture propagation proceeding into ply 25c of rupture strip 17, being of the outside ply type, and finally with rupture propoga-tion proceeding along dashed line segment 30b by interlayer delamination between outer ply 25c and barrie{ ply 26C and continuing to the bottom of rupture strip 17, at which time the bag mouth is rendered open.
If reclosure of the bag is desired, for example after partially removing the contents of the bag, the top edge of the bag is rolled down and reclosure element 18 is crimped in a dead-fold retaining the reclosed configuration. Reclosure element 18 is shown adhered to the rupture side of rupture strip 17 which has the advantage that rupture strip 17 is less Y18LL8/sb ~ ~
Z;24B5 likely to be ~rabbed along with front panel ]1 when initially opening the bag. Alternatively, reclosure element 18 may be adhered to the other side of rupture strip 17 so as not to hamper reinsertion of package contents after partial use.
In FIG. 3, a variation of the previous embodiment is shown wherein side-sealed bag 35 has a rupture strip extending the full width of the bag. Thus, rupture strip 38 having adhered coextensive reclosure element 39 is sealed between front panel 36 and rear panel 37 at mouth seal 42 and extends the full width of the bag through side seals 40a,b to the sides of the bag at 41a,b respectively. The advantage of this mode lies in enhanced manufacturing convenience, as further discussed below.
Essentially, this full width rupture strip facilitates continuous manu-facture of a series of indefinite length of such bags. In this embodi-ment, the rupture strip is Decessarily spaced below the top of the bag to preserve side-seal integrity upon opening the bag, i.e. upoh rupturing seal 42. For example, the upper segment-of side-seal 40a as indicated at 45 will be of the inside-to-inside type heat seal while side-seal segment 46 will be of the same seal cross-section as that at mouth seal 42, i.e.
including an easy open seal of an inside-to-outside character. Thus, in opening the bag, by grabbing the top edges of the bag panels respectively and pulling outwardly, the top of the side-seals will likely not rupture before the rupture of easy-open mouth seal 42, in normal use. As a general rule of thumb in this mode rupture strip 38 is spaced below the top of the bag as indicated at 43 by a distance very roughly equal to the width of the rupture strip as indication at 44. However, in any given situation this spacing is optimally determined empirically. Generally, it is expected that the side-seal integrity of the previous ernbodiment will be somewhat superior to that of this embodiment.
In FIG. 4, a variant of the mode of FIG. 2 is shown in cross-Y]8LL9/sb section. The frontal configura~ion of this embodiment may alternatively be that of ~IG. 1 or 3. Thus, a side-sealed bag 50, shown in cross-sec-tion, has front panel 51 and rear panel 52 with rupture strip 53 being folded downwardly about a reclosure element 54 with the folded ends of rupture strip 53 being sealed in mouth seal 55. As before, rupture strip S3 is of the same film as the panels of the bag. Further, rupture strip 53 is folded so that outer ply 56c being the same as outer plies 56a,b on panels 51 and 52 respective]y, is outward so that as indicated at 57 there is an inside to-outside heat seal and also at 59, while at 58 there is an inside-to-inside heat seal. In use, as before, to open the bag the upper edges of panels 51 and 52 are grabbed and pulled outwardly respec-tively causing rupture of the mouth seal at either 57 or 59, most likely according to the mode discussed above whereby rupture propagates essen-tially by interlayer delamination to the bottom of the rupture strip.
One advantage of this embodiment is that the reclosure elemen~t need not be adhered to the rupture strip as it is freely contained in the fold of rupture strip 53 as shown. Further, as discussed below this mode simplifies manufacture of bags according to the invention.
In FIG. 5, there is schematically shown a continuous process for making a perforated series of indefinite length of the bags of FIG.
4. Rolls 60 and 62 are rolls of single-wound film for the bag panels, respectively, feeding out in the direction indicated by arrow 61. Roll 63 feeds out double-wound film, i.e. folded film, to provide the rupture strip. Spool 64 feeds out a continuous wire element 65 to provide the reclosure element. Wire element 65 passes around guide roll 66 which lies within the fold of the double-wound film feeding out from roll 63.
The continuous feed of folded rupture strip and reclosure element passes over the feed-out of roll 62; thus, at location 68 there is the layered configuration consisting of the rear bag panel, the lower side of the Y18LL10/sb 4~5 folded rupture strip, ~hen the reclosure element, and then the upper side of the rupture strip. This assemblage then passes under the feed-out from roll 60 to provide an assemblage at location 69 being that of loca-tion 68 plus an overlying sheet of front panel. This final assemblage passes first through a transverse heat sealer 74, such as a conventional double-belt heat sealer system, to continuously form a mouth seal 75 along the bag series and then through a conventional side heat sealer and perforating device so that at regular intervals there are formed pàirs of side-seals 71a,b about a line of perforation 72. The conventional cutter that forms line of perforation 72 has the added feature that an elongated cut is made at 73 across the reclosure element and the rupture strip.
Thus, at 61 a continuous chain of perforated sidesealed bags feeds out.
Note further that this finished product will resemble the mode indicated in FIG. 3 wherein the rupture strip extends the full width of the bag, i.e. through the side heat seals to the perforated side edges of the bag.
In FIG. 6 there is depicted a variation on the process of FIG.
5 being adapted for making continuously the embodiment of FIG. 1 wherein each rupture strip with coextensive reclosure element lies within the side-seals of each bag respectively. FIG. 6 shows this process version according to a side view, whereas FIG. 5 depicts a plan view. Reference numerals in FIG. 6 generally correspond to like numerals in FIG. 5, representing similar components. Roll 60a feeds out film for the front panel of the bag with feed direction indicated at arrow 61a. Roll 62a feeds out the same type of film for the rear panel of the bag. Roll 63a feeds out single-wound film of the same type for rupture strip 67a. Roll 64a feeds out a strand of adhesively coated wire as the reclosure element 65a, the adhesive coating on the wire being a conventional pressure sensitive adhesive. The continuous feed of rupture strip 67a passes along with the continous feed of reclosure wire 65a over rigid surface 75 Y18L~11/sb ~L~2'~35 and through the cutting action of conventional cutter 76. Cutter 76 intermittently shears off sets of rupture strip and reclosure wire at regular intervals, with the sheared segments then passing under a conven-tional pusher 77 which presses strip-wire segment 78 against rear panel feed 68a and in turn against rigid surface 79 whereby the pressure sensitive adhesive on the reclosure wire is activated to adhere the reclosure wire to the rupture strip and to the bag panel. This cutting and stamping action is adjusted with a frequency according to the desired bag width. From this point forward in the process, as indicated generally at location 69a, all aspects are substantially similar to those aspects given in the discussion of FIG. 5 Although the present invention has been described in conjunc-tion with preferred embodiments, it is ;o be understood that modifica-tions and variations may be utilized without departing from the princi-pals and scope of the invention, as those skilled in the art will readily understand. Accordingly, such modifications and variations may be prac-ticed within the scope of the following claims:
Y18LL12/sb
This invention rela~es generally to a thermoplastic package of a composite film which, when heat sealed about an article, is easily openable. More particularly, this invention relates to an easy open bag having an easy-open rupture element which is heat sealed in the 00uth of said bag.
Cheese, iuncheon meat, and other products are frequently pack-aged in bags of thermoplastic film wrapped about the product and heat sealed to itself forming closure seams. In many cases, it is a problem to open the package without destroying the package thereby leaving it unsuitable for convenient reclosure. The problem is compounded because ~he films for packaging such products as cheese and luncheon meat should be strong and abuse resistant and have desirable gas transmission prop-erties, yet at the same time be capable of being opened without destroy-ing the package. Thus, it is a principal object of this invention to provide a closure and seal configuration which is easily opened by a relatively small opening force so as not to destroy the package.
Numerous packaging configurations have been proposed in the past which employ easy open features. ~or example, U.S. Patent 3,655,503 issued April 11, 1972 to Stanley et al shows a package closure seal wherein multilayer films are sealed together, which when pulled apart to open the package rupture and delaminate only in the seal area. U.S.
Patent No. 3,536,501 issued October 27, 1970 to Work shows a package in which the edge of its closure flap is folded over so that the outer film layer is sealed to itself. U.S. Patent 3,471,005 issued October 7, 1969 to Sexstone shows a pouch with its front panel folded inwardly at the pouch mouth and sealed to the rear panel of the pouch. U.S. Patent 3,460,742 issued August 12, 1969 to Langdon shows a package with its bottom left open for receiving an article and subsequent sealing and with Y]~LL2/sb its mouth-end formed with sealed tabs which are readily peeled open to expose the contained article for removal.
An associated problem encountered in easy open packaging is that of providing means for reclosure, for e~ample when it is desirable that the opened package be effectively reclosed to protect any unused portion of the package contents. Numerous reclosure elements have been proposed in the prior art, including those disclosed in U.S. Patents 4,117,934 issued October 3, 1978; 4,126,085 issued November 21, 1978;
4,174,597 issued November 20, 1979; and 4,138,932 issued February 13, 1979, all to Mowli et al and which deal with "twist tie" elements having dead~fold characteristics, i.e. once bend or folded the element remains in its bent shape and does not spring back or tend to return to its original shape thereby retaining the reclosure.
S~nYARY O~ THE INVENTION
The present invention provides a bag of thermoplastic film that is easily openable at a peelable heat seal along a rupture strip in the bag mouth, optionally having a reclosure element, and being especially adapted for packages made from multiply film in which inner ply heat seals are of relatively high strength, for example where the irlner ply is irradiatively cross-linked but the outer ply is not. The invention is especially suited for continuous manufacturing processes wherein a sepa-rable series of packaging bags is continuously produced. The invention obviates any need to turn inward a bag panel edge in the vicinity of the mouth seal to attain easy openability.
In the article aspects of the invention, there is provided an easy open package comprising a side-sealed bag of multiply thermoplastic film having inside and outside plies characterized in that inside-to-Y18LL3/sb 8~
inside ply heat seal s~rength is greater than inside-to-outside ply heat seal strength; and a rupture strip of film, being the same material as the film of said bag, interposed between the surfaces of the mouth of said bag, said bag mouth being heat sealed throug~ said strip forming one inside-to-inside type heat seal and at least one inside-to-outside type heat seal. Preferably, the inside ply of said film is irradlatively cross-linked, while the outside ply is not.
In one mode, the rupture strip is sealed in the package mouth in a folded configuration. In another mode, the rupture strip is not folded, but rather is flatly configured in the mouth seal. Optionally, the rupture strip may extend through the side-seals of the bag. Prefer-ab~y, said easy open pachage further includes a reclosure element.
In the method aspects of the invention, there is provided a method from making an easy open bag comprising providing for the panels of said bag two opposingly facing sheets of a multiply thermoplastic film having inside and outside plies characterized in that inside-to-inside ply heat seal strength is greater than inside-to-outside ply heat seal strength; interposing a rupture strip of film, ~eing the same material as the film of said bag, between said sheets toward and substantially par-allel to a transverse edge of said sheet pair; forming side heat seals across said sheet pair being transverse said strip direction and spaced equal to the interior width of said bag; and then forming a bag mouth heat seal along said strip such that there is one inside-to-inside type heat seal and at least one inside-to-outside type heat seal within said mouth seal.
Y18LL4/sb --3 ~
BRIEF DESCRIPT[ON OF THE DRAWINGS
Further details are given below with reference to the embodi-ments shown in the drawings wherein:
FIG. 1 is a front view of a side-sealed bag of the invention having a rupture strip sealed in the mouth of the bag;
FIG. 2 is a vertical cross-section through the bag mouth in FIG. l;
FIG. 3 is similar to FIG. 1 except that a rupture strip sealed in the mouth of a side-sealed bag extends transversely through the side-seals;
FIG. 4 shows an alternative embodiment in cross-section similar to FIG. 2 except that a rupture strip sealed in the mouth of a bag is folded downwardly over a reclosure element;
FIG. 5 schematically depicts a method for making the embodiment shown in FIG. 4, further in which the folded rupture strip and reclosure element extend through the side-seals of the bag as in FIG. 3; and FIG. 6 depicts a variant rnethod for making the embodiment shown in FIG. 1, in which the rupture strip and reclosure element do not extend through the side-seals of the bag.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring specifically to the drawings, in FIG. 1 there is shown a preferred embodiment 10 of the invention which is a side-sealed bag shown in the frontal view having a rupture strip sealed in the mouth of the bag which permits easy opening by an ultimate user to remove a con~ained product. The bag has front and rear panels, 11 and 12 respec-tively, of conventional thermoplastic packaging film joined by side heat seals 13a,b. The front and rear panels are dimensioned longitudinally such that there is an extended lip 14 at the mouth end of the bag and Y18LL5/sb ~ZZ ~5 an extended lip 15 at the bottom end of the bag. The mouth end o~ the bag is transversely heat sealed at 16. The bottom end of the bag is left ~ f open so that a product may be initially loaded into the bag, after which the bag bottom is heat sealed. The bottom extended lip 15 facilitates opening for initially loading the product into the bag. The extended lip 14 at the mouth end of the bag facilitates opening of the bag by the ultimate user to remove the product from the bag. In accordance with the invention, there is a rupture strip 17 inserted in the mouth of the bag between the front and rear bag panels and being sealed in the mouth seal 16. Rupture strip 17, in this embodiment, lies between side-seals 13a,b.
Reclosure element 18, such as a twist-tie, is adhered to the rupture i strip, being generally coextensive therewith and lying above the mouth seal. Thus, in use a producer inserts a product in the bottom of the bag by separating front panels 11 and 12 using bottom extended lip 15 and then transversely heat seals the bottom of the bag. The packaged article ! eventually passes to the ultimate user who opens the mouth end of the bag by first separating front and rear panels 11 and 12 utilizing extended .
lip 14 and then puliing outwardly to rupture that part of mouth seal 16 that is coextensive with rupture strip 17. This selected rupture mode is a key aspect of the invetion and is further discussed below. The contents of the package may then be partially removed, if desired, and the bag reclosed by rolling down the top of the bag and crimping reclosure element 18, being a conventional dead-fold reclosure element, i.e. once crimped does not substantially spring back.
A ke-y element of the invention concerns the type of film from which the bag and rupture strip are made. The rupture strip and the bag panels are of the same film. The film is characterized generally in that the inner and outer surface plies have differing heat sealing character-istics such that an inside-to-inside ply heat seal is substantially Y18LL6/sb _ ~ _ ~2 ~5 stronger than an inside-~o-outside ply heat seal (or an outside-to-outside heat seal). This situation arises when, for example, the inside ply is irradiatively cross-linked but not the outside ply. Representatively, such a film is disclosed in U.S. Patent 3,741,253 issued June 26, 1973 to Brax et al for "Laminates of Ethylene Vinylacetate Polymers and Polymers of Vinylidene Chlorlde" directed to a multiply packaging film having an inner layer of cross-linked ethylene vinylacetate polymer~ a directly joined middle layer of vinylidene chloride polymer, and an outer layer directly joined to the middle layer of an ethylene-vinylacetate polymer.
Such films of differing surface ply characteristics come about frequently due to processing limitations. For example, the inner ply is first hot blown as a tubular extrudate and then irradiatively cross-linked to enhance strength of the film and to enhance shrink capacity. Then a middle barrier layer and an outer abuse layer are extrusion coated onto this irradiatively crosslinked substrate to build up a barrier shrink film. Irradiative treatement is conducted prior to addition of the barrier ply since such treatment frequently has adverse effects on conven-Scl~a~ c~cle~allk) tional barrier material, particularly ~ ~.
In FIG. 2 there is shown a cross-sectional view taken along line 2-2 in FIG. 1 through the mouth of bag 10. Thus, there are shown front and rear panels 11 and 12 respectively, with rupture strip 17 interposed between them with its lower portion sealed in mouth seal 16.
Reclosure element 18 is shown affixed near the top of-rupture strip 17 being generally above mouth seal 16. The exemplary thermoplastic film as sho~n is a three-ply film having outer layer 25 serving as an abuse layer covering a middle barrier layer 26 which in turn is over a shrink layer 27. Front panel 11, rear panel 12, and rupture strip 17 are all of the same type film. As discussed above, the interior shrink layer 27 is ~]8LL7/sb - ~o irradiatively cross-linked, while outer abuse layer 25, which representa-tively is of ~he same composition, is not irradiatively cross-linked due to processing limitations discussed above. Thus, the inside-to-inside ply heat seal at 28 is substantially stronger than the inside-to-outside ply heat seal 23. Representative materials which can be suitably used in the invention are polyethylene and ethylene-vinyl acetate copol~mers in general for the material for the outer layer; materials selected from the group consisting of nylon, vinylidene chloride copolymers, propylene homopolymers and copolymers are suitable for the interior; and, cross-linked polye~hylene and ethylene-vinyl acetate copolymers are suitable for the inner layer.
To open the easy-open package, a user opposingly grabs the upper edges of front panel 11 and rear panel 12 respectively and pulls outwardly. The top of rupture strip 17 is spaced below the top of the bag as indicated at 19 so that rupture strip 17 is not likely grabbed along with either the front or rear panel during opening. It is believed that the most likely mode of rupture of the easy open seal is as indi-cated along dashed line 30 with rupture initiating at dashed line segment 30a near the top oE the mouth heat seal 16 at the inside-to-outside seal 29, then with rupture propagation proceeding into ply 25c of rupture strip 17, being of the outside ply type, and finally with rupture propoga-tion proceeding along dashed line segment 30b by interlayer delamination between outer ply 25c and barrie{ ply 26C and continuing to the bottom of rupture strip 17, at which time the bag mouth is rendered open.
If reclosure of the bag is desired, for example after partially removing the contents of the bag, the top edge of the bag is rolled down and reclosure element 18 is crimped in a dead-fold retaining the reclosed configuration. Reclosure element 18 is shown adhered to the rupture side of rupture strip 17 which has the advantage that rupture strip 17 is less Y18LL8/sb ~ ~
Z;24B5 likely to be ~rabbed along with front panel ]1 when initially opening the bag. Alternatively, reclosure element 18 may be adhered to the other side of rupture strip 17 so as not to hamper reinsertion of package contents after partial use.
In FIG. 3, a variation of the previous embodiment is shown wherein side-sealed bag 35 has a rupture strip extending the full width of the bag. Thus, rupture strip 38 having adhered coextensive reclosure element 39 is sealed between front panel 36 and rear panel 37 at mouth seal 42 and extends the full width of the bag through side seals 40a,b to the sides of the bag at 41a,b respectively. The advantage of this mode lies in enhanced manufacturing convenience, as further discussed below.
Essentially, this full width rupture strip facilitates continuous manu-facture of a series of indefinite length of such bags. In this embodi-ment, the rupture strip is Decessarily spaced below the top of the bag to preserve side-seal integrity upon opening the bag, i.e. upoh rupturing seal 42. For example, the upper segment-of side-seal 40a as indicated at 45 will be of the inside-to-inside type heat seal while side-seal segment 46 will be of the same seal cross-section as that at mouth seal 42, i.e.
including an easy open seal of an inside-to-outside character. Thus, in opening the bag, by grabbing the top edges of the bag panels respectively and pulling outwardly, the top of the side-seals will likely not rupture before the rupture of easy-open mouth seal 42, in normal use. As a general rule of thumb in this mode rupture strip 38 is spaced below the top of the bag as indicated at 43 by a distance very roughly equal to the width of the rupture strip as indication at 44. However, in any given situation this spacing is optimally determined empirically. Generally, it is expected that the side-seal integrity of the previous ernbodiment will be somewhat superior to that of this embodiment.
In FIG. 4, a variant of the mode of FIG. 2 is shown in cross-Y]8LL9/sb section. The frontal configura~ion of this embodiment may alternatively be that of ~IG. 1 or 3. Thus, a side-sealed bag 50, shown in cross-sec-tion, has front panel 51 and rear panel 52 with rupture strip 53 being folded downwardly about a reclosure element 54 with the folded ends of rupture strip 53 being sealed in mouth seal 55. As before, rupture strip S3 is of the same film as the panels of the bag. Further, rupture strip 53 is folded so that outer ply 56c being the same as outer plies 56a,b on panels 51 and 52 respective]y, is outward so that as indicated at 57 there is an inside to-outside heat seal and also at 59, while at 58 there is an inside-to-inside heat seal. In use, as before, to open the bag the upper edges of panels 51 and 52 are grabbed and pulled outwardly respec-tively causing rupture of the mouth seal at either 57 or 59, most likely according to the mode discussed above whereby rupture propagates essen-tially by interlayer delamination to the bottom of the rupture strip.
One advantage of this embodiment is that the reclosure elemen~t need not be adhered to the rupture strip as it is freely contained in the fold of rupture strip 53 as shown. Further, as discussed below this mode simplifies manufacture of bags according to the invention.
In FIG. 5, there is schematically shown a continuous process for making a perforated series of indefinite length of the bags of FIG.
4. Rolls 60 and 62 are rolls of single-wound film for the bag panels, respectively, feeding out in the direction indicated by arrow 61. Roll 63 feeds out double-wound film, i.e. folded film, to provide the rupture strip. Spool 64 feeds out a continuous wire element 65 to provide the reclosure element. Wire element 65 passes around guide roll 66 which lies within the fold of the double-wound film feeding out from roll 63.
The continuous feed of folded rupture strip and reclosure element passes over the feed-out of roll 62; thus, at location 68 there is the layered configuration consisting of the rear bag panel, the lower side of the Y18LL10/sb 4~5 folded rupture strip, ~hen the reclosure element, and then the upper side of the rupture strip. This assemblage then passes under the feed-out from roll 60 to provide an assemblage at location 69 being that of loca-tion 68 plus an overlying sheet of front panel. This final assemblage passes first through a transverse heat sealer 74, such as a conventional double-belt heat sealer system, to continuously form a mouth seal 75 along the bag series and then through a conventional side heat sealer and perforating device so that at regular intervals there are formed pàirs of side-seals 71a,b about a line of perforation 72. The conventional cutter that forms line of perforation 72 has the added feature that an elongated cut is made at 73 across the reclosure element and the rupture strip.
Thus, at 61 a continuous chain of perforated sidesealed bags feeds out.
Note further that this finished product will resemble the mode indicated in FIG. 3 wherein the rupture strip extends the full width of the bag, i.e. through the side heat seals to the perforated side edges of the bag.
In FIG. 6 there is depicted a variation on the process of FIG.
5 being adapted for making continuously the embodiment of FIG. 1 wherein each rupture strip with coextensive reclosure element lies within the side-seals of each bag respectively. FIG. 6 shows this process version according to a side view, whereas FIG. 5 depicts a plan view. Reference numerals in FIG. 6 generally correspond to like numerals in FIG. 5, representing similar components. Roll 60a feeds out film for the front panel of the bag with feed direction indicated at arrow 61a. Roll 62a feeds out the same type of film for the rear panel of the bag. Roll 63a feeds out single-wound film of the same type for rupture strip 67a. Roll 64a feeds out a strand of adhesively coated wire as the reclosure element 65a, the adhesive coating on the wire being a conventional pressure sensitive adhesive. The continuous feed of rupture strip 67a passes along with the continous feed of reclosure wire 65a over rigid surface 75 Y18L~11/sb ~L~2'~35 and through the cutting action of conventional cutter 76. Cutter 76 intermittently shears off sets of rupture strip and reclosure wire at regular intervals, with the sheared segments then passing under a conven-tional pusher 77 which presses strip-wire segment 78 against rear panel feed 68a and in turn against rigid surface 79 whereby the pressure sensitive adhesive on the reclosure wire is activated to adhere the reclosure wire to the rupture strip and to the bag panel. This cutting and stamping action is adjusted with a frequency according to the desired bag width. From this point forward in the process, as indicated generally at location 69a, all aspects are substantially similar to those aspects given in the discussion of FIG. 5 Although the present invention has been described in conjunc-tion with preferred embodiments, it is ;o be understood that modifica-tions and variations may be utilized without departing from the princi-pals and scope of the invention, as those skilled in the art will readily understand. Accordingly, such modifications and variations may be prac-ticed within the scope of the following claims:
Y18LL12/sb
Claims (24)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An easy open package, comprising:
a) a side-sealed bag of multiply thermoplastic film having inside and outside plies characterized in that inside-to-inside ply heat seal strength is greater than inside-to-outside ply heat seal strength;
nd b) a rupture strip of film, being the same material as the film of said bag, interposed between the surfaces of the mouth of said bag, said bag mouth being heat sealed through said strip forming one inside-to-inside type heat seal and at least one inside-to-outside type heat seal.
a) a side-sealed bag of multiply thermoplastic film having inside and outside plies characterized in that inside-to-inside ply heat seal strength is greater than inside-to-outside ply heat seal strength;
nd b) a rupture strip of film, being the same material as the film of said bag, interposed between the surfaces of the mouth of said bag, said bag mouth being heat sealed through said strip forming one inside-to-inside type heat seal and at least one inside-to-outside type heat seal.
2. The package of claim 1 wherein said strip extends across the width of said bag and is spaced below the mouth-end termini of the side-seals of said bag.
3. The package of claim 1 further comprising a reclosure element.
4. The package of claim 3 wherein said reclosure element is an elongate dead-fold element adhered to said strip.
5. The package of claim 4 wherein said dead-fold element is coex-tensive with said strip.
6. The package of claim 1 wherein said strip is folded so that at the bag-strip interfaces their respective plies confront in an inside-to-outside ply configuration.
7. The package of claim 6 further comprising a reclosure element.
8. The package of claim 7 wherein said reclosure element is an elongate dead-fold element inside the fold of said strip and lies above said mouth seal.
9. The package of claim 8 wherein said dead-fold element is coex-tensive with said strip.
10. The package of claim 1 or 2 wherein the bottom of said bag is open.
11. The package of claim 1 or 2 wherein said bag contains a product and the bottom of said bag is heat sealed.
12. The package of claim 1 wherein said multiply film has an outer abuse layer, an interior barrier layer, and an inner shrink layer, further provided that said inner layer is crosslinked and said outer layer is not crosslinked.
13. The package of claim 12 wherein said outer layer and said inner layer are of substantially the same composition.
14. The package of claim 12 wherein said film is three-ply having an outer layer selected from the group consisting of polyethylene and ethylene-vinyl acetate copolymers; an interior layer selected from the group consisting of nylon, vinylidene chloride copolymers, and propylene homopolymers and copolymers; and an inner layer selected from the group consisting of irradiatively cross-linked polyethylene and ethylene-vinyl acetate copolymers.
15. A method for making an easy open bag, comprising:
a) providing for the panels of said bag two opposingly facing sheets of a multiply thermoplastic film having inside and outside plies characterized in that inside-to-inside ply heat seal strength is greater than inside-to-outside ply heat seal strength;
b) interposing a rupture strip of film, being the same mate-rial as the film of said bag, between said sheets toward and substan-tially parallel to a transverse edge of said sheet pair:
c) forming side heat seals across said sheet pair being transverse said strip direction and spaced equal to the interior width of said bag; and then d) forming a bag mouth heat seal along said strip such that there is one inside-to-inside type heat seal and at least one inside-to-outside type heat seal within said mouth seal.
a) providing for the panels of said bag two opposingly facing sheets of a multiply thermoplastic film having inside and outside plies characterized in that inside-to-inside ply heat seal strength is greater than inside-to-outside ply heat seal strength;
b) interposing a rupture strip of film, being the same mate-rial as the film of said bag, between said sheets toward and substan-tially parallel to a transverse edge of said sheet pair:
c) forming side heat seals across said sheet pair being transverse said strip direction and spaced equal to the interior width of said bag; and then d) forming a bag mouth heat seal along said strip such that there is one inside-to-inside type heat seal and at least one inside-to-outside type heat seal within said mouth seal.
16. The method of claim 15 wherein the length of said strip is less than said side-seal spacing.
17. The method of claim 15 wherein the length of said strip is at least equal to said side-seal spacing, provided that said strip is spaced from the termini of said side-seals.
18. The method of claim 16 or 17 further comprising folding said strip such that in forming said bag mouth heat seal there is formed one inside-to-inside type heat seal and at least two inside-to-outside type heat seals.
19. The method of claim 16 or 17 further comprising continuously forming a series of said bags.
20. The method of claim 16 further comprising providing an integral reclosure element.
21. The method of claim 20 further comprising securing an elongate dead-fold element coextensively with said strip.
22. The method of claim 16 wherein said multiply film has an outer abuse layer, an interior barrier layer, and an inner shrink layer, further provided that said inner layer is crosslinked and said outer layer is not crosslinked.
23. The method of claim 22 wherein said outer layer and said inner layer are of substantially the same composition.
24. The method of claim 22 wherein said film is three-ply having an outer layer selected from the group consisting of polyethylene and eth-ylene-vinyl acetate copolymers; an interior layer selected from the group consisting of nylon, vinylidene chloride copolymers, and propylene homo-polyers and copolymers; and an inner layer selected from the group con-sisting of irradiatively cross-linked polyethylene and ethylene-vinyl acetate copolymers.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US43334782A | 1982-10-08 | 1982-10-08 | |
| US433,347 | 1989-11-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1222485A true CA1222485A (en) | 1987-06-02 |
Family
ID=23719840
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000433778A Expired CA1222485A (en) | 1982-10-08 | 1983-08-03 | Easy open bag having rupture strip |
Country Status (4)
| Country | Link |
|---|---|
| JP (2) | JPS5974067A (en) |
| AU (1) | AU1464983A (en) |
| CA (1) | CA1222485A (en) |
| ZA (1) | ZA833340B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5330269A (en) * | 1991-11-08 | 1994-07-19 | Toyo Aluminum Kabushiki Kaisha | Package |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0759521B2 (en) * | 1985-09-30 | 1995-06-28 | 藤沢薬品工業株式会社 | Gel layer-forming sustained-release preparation |
| JPH07112746A (en) * | 1993-10-19 | 1995-05-02 | Idemitsu Petrochem Co Ltd | Easily openable sealed bag |
| JP4857658B2 (en) * | 2005-08-24 | 2012-01-18 | トヨタ自動車株式会社 | Suspension device |
-
1983
- 1983-05-10 ZA ZA833340A patent/ZA833340B/en unknown
- 1983-05-18 AU AU14649/83A patent/AU1464983A/en not_active Abandoned
- 1983-08-03 CA CA000433778A patent/CA1222485A/en not_active Expired
- 1983-09-14 JP JP58168489A patent/JPS5974067A/en active Pending
- 1983-10-07 JP JP58187157A patent/JPS6051107A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5330269A (en) * | 1991-11-08 | 1994-07-19 | Toyo Aluminum Kabushiki Kaisha | Package |
Also Published As
| Publication number | Publication date |
|---|---|
| ZA833340B (en) | 1984-01-25 |
| JPS6051107A (en) | 1985-03-22 |
| JPS5974067A (en) | 1984-04-26 |
| AU1464983A (en) | 1984-04-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |