Tamper-evident, flexible, reclosable packages

Abstract: A reclosable, hermetically-sealed flexible package (1) which has an inner, hermetic peelable seal (16) and a reclosure seal, typically including interlocking closure strips (17, 18), is provided with one or more of various tamper-evident features (21;31;31a;31b;41;51;61;62;63) which provides an easily visible and noticeable indication of disruption thereof of the type that would gain access to the reclosure seal (17, 18).

Description: Field of the Invention This invention relates to flexible, bag-like packages according to the preamble of claim 1 which are provided with an inner, hermetic peel seal and an outer reclosure seal, such as a zipper seal. These packages provide convenience to the consumer in that the contents of the package may be easily accessed by first opening the reclosure seal and then separating the hermetic peel seal. After removing a portion of the package contents, the package can be reclosed by means of the reclosure seal. Description of the Prior Art Flexible packages which have an inner, hermetic peelable seal and an outer zipper seal are presently known for packaging various food products, such as wieners, bacon, sliced luncheon meats, chops, cheese and the like. These packages, including the materials of construction, are fully described in US-A-4782951 and US-A-4823961 (both Hustad and Griesbach). A common use of such packaging is to vacuum seal the food product between two sheets of film material to form a generally rectangularly shaped package which is hermetically sealed (e.g., heat sealed) with a single, non-reclosable seal about three sides and which has an access opening at the fourth side which includes both a hermetic, non-reclosable seal and a reclosure seal. When the access opening consists of an outer zipper reclosure seal and an inner, non-reclosable, peel seal, it has been found that the package may be opened and then reclosed without showing outwardly visible evidence of such openings. Thus, a package which has been opened and thereafter reclosed, but from which no contents have been removed, would have an outward appearance comparable to a package which retains its inner, hermetic peel seal. A consumer who purchases and thereafter opens a previously-opened package would of course, especially for vacuum-packed products, be able to determine that the hermetic seal had been broken. Determining that a gas-flushed package had been previously opened might possibly be more difficult. It would, however, be preferred that it be readily apparent to the consumer in the store (i.e. before purchase) that the package had been previously opened. Various techniques have been known for providing visual, tamper-evident features on flexible packages. US-A-3780781 (Uramoto), US-A-4015771 (Sengevald) and US-A-4786190 (Van Erdan et al.) are examples of such tamper-evident packages. Tamper-evident features have not, however, been previously used on flexible packages which have an inner, hermetic peel seal and an outer reclosable seal. Copending applications directed to this general combination of features include EP-A-0393810 and EP-A-0384588, both filed 30th January 1990. GB-A-1010738 (Flexigrip) discloses a package according to the preamble of claim 1 with interlocking closure strips which are formed integrally with a perforated central strip of a closure sheet. The closure strips do not overlap the wall panels of the package. Summary of the Invention The present invention provides a reclosable, flexible package within the interior of which a product is hermetically sealable between opposed wall panels, the package being permanently sealed about not more than three sides of its periphery and having a further side of its periphery intended for access to the product, a reclosure seal means including interlocking closure strips being located inwardly of the access side of the package, wherein the package includes tamper-evident means for at least partially closing access through the access side edge of the package and for permitting access to the package interior by digital forces applied to the tamper-evident means during opening of the package, the tamper-evident means including a disruptable sealing member which provides a visible signal of opening, characterised by a hermetic peel seal located inwardly of and adjacent to the reclosure seal means and in that the disruptable sealing member comprises at least one strip member which extends continuously or discontinuously along the access side of the package and which is bonded to the top edge of at least one of the opposing wall panels at a location which overlaps the interlocking closure strip bonded to that wall panel, whereby a triple-layer structure comprising the strip member, the wall panel and the closure strip is formed. The package of the present invention has a unique combination of features. The package is in-store tamper-evident, such that it is apparent to the consumer that the package has been opened upon even casual examination of the package. The package is liquid-tight and suitably retains within the package fluids of products contained therewithin, including water, juices, oils and the like. The package has a reclosure seal which can be opened and reclosed a number of times in order to remove portions of the package contents. Additionally, the package has a hermetic, inner seal which is an easy-open or peel seal. The peel seal is generally parallel to the reclosure seal and is opened with digital pull-apart forces which may be a continuation of the forces used to open the reclosable seal. The peel seal can maintain a vacuum, a pressurized and/or a modified gaseous environment within the flexible package. The peel seal will be formed by effecting a face-to-face seal between two plys of plastic film with the strength of the seal permitting separation without destruction or tearing of either ply. As described in the Hustad and Griesbach patents, the contacting surface of the two plys should be of dissimilar materials in order to produce the desired peel seal. The package of this invention further includes a tamper-evident feature which must be disrupted in order to gain access to the product. The disruption of the tamper-evident feature will provide visible evidence of the fact that entry to the contents of the bag, through the reclosure seal and the inner peel seal, may have occurred. As with the package of the Hustad and Griesbach patents, the tamper-evident, reclosable and hermetically-sealed package of this invention may be made on a single machine using a straight-through process. The features and objects of the present invention will be readily apparent from the following detailed description thereof taken in conjunction with the accompanying drawings. Brief Description of the Drawings Figure 1 is a perspective view, partially broken away, of one embodiment of a tamper-evident, reclosable, hermetically-sealed package in accordance with this invention. For purposes of illustration only, the package is shown as containing vacuum-packed wieners. Figure 2 is a cross-sectional view taken along the line 2-2 of Figure 1; Figure 3 is a perspective view, partially in cross-section, illustrating the tear-away aspect of this embodiment; Figure 4 is a cross-sectional view generally vertically oriented and showing the tear-away orientation of Figure 3; Figure 5 is a perspective view, partially in cross-section, of a second embodiment of a package in accordance with this invention; Figure 6 is a perspective view, partially in cross-section, of a third embodiment similar to that of Figure 5; Figures 7 and 8 are perspective views, partially in cross-section, of a fourth embodiment of a package according to the present invention, Figure 7 illustrating the embodiment in its closed orientation, and Figure 8 showing the embodiment in an open orientation; Figure 9 is a perspective view, partially in cross-section, of a fifth embodiment of a package according to the present invention; and Figure 10 is a cross-sectional view of another embodiment on the order of that illustrated in Figure 9. In the drawings, like numerals refer to like elements shown therein. Detailed Description of the Invention In the description of the preferred embodiments set out below, it will be recognized by those skilled in the art that various alternative materials and structures which are not specifically disclosed are also within the scope of this invention. For purposes of illustration and discussion, each bag panel or ply will be shown as a single heat-sealable laminate. In actual practice, each bag panel will likely be a laminate of two or more layers which will provide sufficient protection to the product (e.g., oxygen and moisture barriers) and which can form a peelable, hermetic heat seal and possibly even a non-peelable, hermetic heat seal at their inner surfaces. As is known to the art, a surface of "Saran", a vinylidene chloride-vinyl chloride copolymer, in contact with a surface of ethylene vinyl acetate can form such peelable bonds. The peel seal should have an opening force of from 1.5 to 6.0 pounds (0.68 to 2.72 kg), as discussed in the Hustad and Griesbach patents. The reclosure seal can be comprised of interlocking closure strips which are adhesively bonded or heat sealed to the inner face of each bag panel. Alternatively, the reclosure elements can be formed during the film extrusion process. Elements which constitute the tamper-evident feature will preferably be integral with the bag panels prior to the formation of the bag. Where necessary, such as in the formation of certain heat seals, elements of the tamper evident feature will be added or formed after the bag structure, including the peelable inner seal and the intermediate reclosure seal, has been produced. Figure 1 illustrates a package 1 formed of front and back bag panels 10 and 11 which enclose a plurality of wiener or wiener-shaped products 12. The wieners 12 are vacuum-packed so that the bag panels are in intimate contact with the surface of the wieners. Bag panels 10 and 11 are sealed along side edges 13 and 14 by means of continuous heat seals. The bottom edge (not shown) of the bag may be an additional heat seal. Alternatively, any or all of the side edges and the bottom edge may be a fold which forms a continuous sheet into opposed panels 10 and 11. A hermetic, peel seal extends across the width of the package at 16, the seal being formed by adherent contact between films 10 and 11 as a result of known heat-sealing equipment and techniques. The same heat may be applied to side seals 13 and 14 and bottom seal as is applied to seal area 16 such that all of those seals are equally peelable. The structure of the bag would, however, essentially preclude opening of seals 13, 14 and the bottom seal during normal use. Alternatively, these seals can be formed as non-peelable seals such as by supplying more heat to form these seals than to form seal area 16 or by applying a coating at seal area 16 to prevent formation of a permanent, non-peelable seal. Interlocking reclosure strips 17 and 18 are bonded to bag panels 10 and 11 at a location which is parallel to, spaced apart from, and outside of the seal area 16. As shown, reclosure strips 17 and 18 are also recessed in the mouth of the package 1, away from the top edges of the bag. Positioned between the lips (19 and 20) of the bag is a tamper-evident component 21 which is bonded to the inner face of lips 19 and 20. According to the embodiment of Figures 1-4, tamper-evident component 21 takes the form of the upper, folded over portion of a film member 22 including the interlocking reclosure strips 17 and 18. More particularly, the film member 22 is folded on itself in a manner that permits proper interlocking engagement between the interlocking reclosure strips 17 and 18. The free end portions 23, 24 containing the interlocking reclosure strips 17 and 18, respectively, are secured by suitable generally permanent bonding means to the lips 20 and 19, respectively. The tamper-evident component 21 of this embodiment is further defined by perforations generally adjacent to the lips 19, 20. Preferably, two rows of perforations 25 and 26 are provided in order to facilitate opening of the package 1 by grasping the tamper-evident component 21 in one hand and the top or lip portion of the package 1 in the other hand, whereby the tamper-evident component can be ripped or torn away. If desired, provision could be made for indicating that the component had been removed in order to thereby signal possible tampering or damage prior to purchase by the consumer. This could take the form of a message area 28 which is severed when the perforations are torn through. Alternatively, means could be provided to require much more than digital forces to completely remove the tamper evident component. For example, the rows of perforations can continue for less than the full length of the tamper-evident component 21, as is generally shown in Figure 3. Other alternative or additional means could be incorporated, such as by providing a stop structure or by providing a thickened plastic area at one end of the tamper-evident component. Tamper-evident component 21 could be a heavier extrusion mass than film member 22 to provide more material for gripping and tearing. By tearing away the tamper-evident component 21, access is gained to the lips 19 and 20 and to the interlocking reclosure strips secured thereto, which permits opening of the peel-seal 16 and access to the wieners 12 or the like. As previously stated, the perforations can be generally adjacent to either or both of the lips 19, 20. In this regard, such perforations can be positioned along the web 22 anywhere between a location of at least 1/16th inch (1.59 mm) below top edge 27 to a location as low as the interlocking reclosure strips 17, 18, which latter location may be below the free edge of the lips 19, 20. The embodiment illustrated in Figures 1 through 4 is advantageous because it is especially well-suited to being formed, filled and sealed on existing machinery, requiring minimal modifications to the packaging machinery and/or material used in forming packages having reclosure strips. In addition, this embodiment provides an easily understood tamper indicator while requiring no additional package film or other tamper indicating component, inasmuch as the one-piece film member including the interlocking reclosure strips performs the tamper-evident feature. With reference to the embodiments shown in Figure 5 and in Figure 6, tamper-evident component 31, 31a includes a strip, preferably made of a cellulosic material, which is folded onto itself and secured in a generally permanent manner to the package. More specifically, the free end portions of the tamper-evident strip are secured to the respective outside surfaces of the lips 19 and 20. This strip may be continuous (covering the entire package) or non-continuous acting as a saddle band. By this arrangement, access which permits opening of the interlocking reclosure strips 17 and 18 is possible only upon severance or ripping of the tamper-evident strip. In Figure 5, such severance or the like is facilitated by a single row of perforations 32, preferably located at the top edge of the strip 31. In the embodiment of Figure 6, dual, generally opposing rows of perforations 33 and 34 are provided. Strips 31, 31a can be secured to the package by means of an especially aggressive adhesive, such as one that is particularly well-suited to substantially permanently bind cellulosic materials to polymeric or plastic materials. Also, a message area could span the perforations in the general manner of area 28 shown in Figure 1. Figures 7 and 8 show a tamper-evident component 51 which takes the form of one or more lengths of aggressively adherent tape which is folded over the mouth of the package such that the lips 19 and 20 are in general engagement with each other. The tamper-evident lengths of tape 51 have two distinct attributes which preclude undetected removal of the lengths 51. One of these attributes is that, after the length of tape is adhered to the panels 10 and 11, the adhesive material thereof imparts an obvious and distinct discoloration area 52 on the polymeric material out of which the package panels are constructed. Another feature is that the tape length 51 has a shreddable attribute, whereby it is extremely difficult to completely remove the entirety of the length of tape without leaving residue shreds 53. Figures 9 and 10 illustrate embodiments wherein the upper portion of the package is folded over on itself in order to define a doubled-over package top as generally shown such that the free top edge portion is closely adjacent to or touches one of the bag panels 10 or 11. The tamper-evident component takes the form of an adhesive bead and/or a sheet having adhesive properties which impart either a one-time adherence characteristic or has some other attribute which indicates that the sheet has been detached from its initially, as-sealed condition. When this tamper-evident component is a sheet 61 between the doubled-over package top and one of the bag panels, as in Figure 9, it can, for example, take the form of a tamper-evident composite, of the tamper-evident tape length 51, or of some other material which will not permit undetected reattachment. For example, sheet 61 could also include perforations and optionally with tamper-indicating printing thereat; cellulosic materials are especially suitable for this type of sheet. A suitable tamper-evident composite is a labeling type of material which is the nature of a composite that is separable into two components which are readily apparent when the composite is pulled apart upon gaining access to and/or opening the interlocking reclosure strips 17, 18. The tamper-evident composite 41 typically has a generally uniform appearance before separation thereof into a positive component and a negative component. Typically, same has the appearance of a generally opaque colored strip. For example, the tamper-evident composite could provide the appearance of a white strip. Upon separation of the composite into the positive component and the negative component, one area of the coloration remains secured to the front bag panel 10, while the remainder of the coloration area remains secured to the doubled-over package top. Once the separation of the composite into the positive and negative components has taken place, it is not possible to reverse the onset of the appearance property differences A material that is suitable for providing the tamper-evident composite is a label stock material known by the trademark "Securemark" of 3M Company. Tamper-evident sheets of these types can alternatively or additionally be positioned over the outside surface of the doubled-over end as shown in Figure 10. Sheets 63 falling into this latter category include sheets of cellulosic or non-cellulosic material that will either sever or will peel away without the ability to be readily reattached. Also included in this category are sheets which have an adhesive or the like that imparts a one-time adherence property thereto. Sheet 63 can be perforated or contain a tear strip to ensure that severance occurs and some of the material remains on the bag panel to provide a further indicator that the package is no longer in its totally sealed state. Sheet 63 can also include printing through the tear location. While various embodiments of packages illustrating this invention have been described, it will be apparent that certain modifications and variations therefrom may be made without departing from the scope of this invention. Accordingly, only such limitations are to be imposed thereon as are indicated in the appended claims.

Claims: A reclosable, flexible package (1) within the interior of which a product (12) is hermetically sealable between opposed wall panels (10, 11), the package being permanently sealed about not more than three sides of its periphery and having a further side of its periphery intended for access to the product, a reclosure seal means including interlocking closure strips (17, 18) being located inwardly of the access side of the package, wherein the package includes tamper-evident means for at least partially closing access through the access side edge of the package and for permitting access to the package interior by digital forces applied to the tamper-evident means during opening of the package, the tamper-evident means including a disruptable sealing member which provides a visible signal of opening, characterised by a hermetic peel seal (16) located inwardly of and adjacent to the reclosure seal means and in that the disruptable sealing member comprises at least one strip member (21; 31; 31a; 51; 61; 63) which extends continuously or discontinuously along the access side of the package and which is bonded to the top edge of at least one of the opposing wall panels (10, 11) at a location which overlaps the interlocking closure strip (17 or 18) bonded to that wall panel (11 or 10), whereby a triple-layer structure comprising the strip member (21; 31; 31a; 51; 61; 63), the wall panel (11 or 10) and the closure strip (17 or 18) is formed. A package according to claim 1, wherein the opposed wall panels (10, 11) comprise oxygen-impermeable film and the package is for enclosing perishable food products (12). A package according to claim 1 or 2, wherein the disruptable sealing member includes a continuous strip member (21; 31; 31a) folded onto itself in order to define a folded portion located outwardly of the interlocking closure strips (17, 18), the strip member (21; 31; 31a) including severance means (25, 26; 32; 33, 34) in the folded portion. A package according to claim 3, wherein the free longitudinal edges of the continuous strip member are located between respective opposing wall panels and their respective interlocking closure strips (17, 18), so that a said triple-layer structure, in which the continuous strip member lies between the respective wall panel and the closure strip, is formed on each wall panel. A package according to claim 4, wherein the interlocking closure strips (17, 18) are formed as a one-piece unit with the folded strip member (22). A package according to claim 3, wherein the opposing wall panels (10, 11) are located between respective free longitudinal edges of the continuous strip member (31; 31a) and their respective interlocking closure strips (17, 18), so that a said triple-layer structure, in which the respective wall panel lies between the folded strip member and the respective closure strip, is formed on each wall panel. A package according to any of claims 3, 4 and 6, wherein the closure strip (21; 31; 31a) is a cellulosic member. A package according to any of claims 3 to 7, wherein the severance means comprises a single row of perforations (32) extending longitudinally of the continuous strip member (31) in the region of its fold. A package according to any of claims 3 to 7, wherein the severance means comprises first and second parallel rows of perforations (25, 26; 33, 34) extending longitudinally of the continuous strip member (21; 31a) outwardly of the outer edges of the wall panels (10, 11). A package according to claim 9, wherein both rows (33, 34) lie adjacent to the fold in the closure strip. A package according to claim 9, wherein each row (25, 26) lies spaced from the fold in the closure strip and between the fold and the outer edge of a respective wall panel (10, 11). A package according to any of claims 8 to 11 wherein at least one row of perforations extends through a message area (28) on the closure strip. A package according to any of claims 8 to 12, wherein the row(s) of perforations extend over the entire length of the closure strip. A package according to claim 1 or 2, wherein the disruptable sealing member includes at least one length of aggressively adherent tape (51) folded over the opening of the package, the or each tape length having adhesive means (52) having colouration attributes which become evident and remain on the top of the package upon removal of at least a portion of the tape length (51), the tape length extending over the outer surface of each wall panel to form, with the wall panel (10, 11) and a respective interlocking closure strip (17, 18), a said triple-layer structure. A package according to claim 14, wherein the tape length (51) exhibits strength characteristics which substantially prevent removal of the tape as a unitary mass and which substantially ensure tearing of said tape length (51) during attempted removal thereof. A package according to claim 1 or 2, wherein the disruptable sealing member includes a continuous strip member (61; 63) which is attached to the outer surface of one of the wall panels (10, 11) the portions of which outwardly of the hermetic peel seal (16) are folded-over so that the continuous strip member is secured to the outer surface of the same or the other wall panels (10 or 11), the strip member being attached to the said wall panel so as to form a said triple-layer structure in which the wall panel (10 or 11) lies between the interlocking closure strip (18 or 17) associated therewith and the continuous strip member. A package according to claim 16, wherein the continuous strip member (61; 63) secures the folded-over wall portions, in a one-time releasable manner, to the wall panel (10) of the package which is generally below and adjacent to the free edge of the doubled over package top. A package according to claim 16 or 17, wherein the continuous strip member (63) includes severance means for ensuring that, upon disruption thereof, a portion remains on the folded-over package top and another portion thereof remains on the wall panel (10) to which the strip is attached. A package according to any of claims 16 to 18, wherein the continuous strip member (63) is secured at its edges to different wall panels (10, 11). A package according to any of claims 16 to 18, wherein the continuous strip member (61) is secured at its edges to the same wall panel (10).

Inventors: HUSTAD GERALD O, THIEMANN DANIEL A, WELLS CINDY M, HUSTAD, GERALD O., THIEMANN, DANIEL A., WELLS, CINDY M.
Applicants: MAYER OSKAR FOODS, OSCAR MAYER FOODS CORPORATION
Application year: 1990
Main classification: B65D33
IPC codes: B65D33, B65D55