Tamper-evident, reclosable, flexible packages

Abstract: A reclosable, hermetically-sealed flexible package which has an inner, hermetic peel seal (16) and a reclosure seal comprised of interlocking closure strips (17, 18) is provided with a tamper-evident feature (21) located peripheral to the reclosure seal. The tamper-evident feature (21) must be visibly disrupted to gain access to the reclosure seal.

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 weiners, bacon, sliced luncheon meats, chops, cheese and the like. These packages, including the materials of construction, are fully described in US-A-4782951 (corresponding to the preamble of claim 1) (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 rectangular 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 has 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 Erden 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. US-A-3073507 (Trewella et al) discloses a flexible bag which, to allow entrance of sterilizing gases, has a folded paper insert secured in its mouth. When it is desired to open the bag, the upper end of the paper insert is torn off. If it is desired to seal the bag completely after sterilization, the bag, if made of a thermoplastic film material, can be fused together by heat sealing along a line below the paper insert. In such circumstances, the paper insert does not aid opening the bag. SUMMARY OF THE INVENTION The present invention provides a reclosable, flexible package wherein a product is hermetically sealed between opposed wall panels, the package being permanently sealed about its bottom and side peripheries and sealed with a hermetic peel seal adjacent the product towards the top of the package and having a reclosure seal comprising interlocking closure strips and located adjacent and peripheral to the hermetic peel seal and below the top edge of the package, characterised by a tamper-evident feature located above the reclosure seal of the package, wherein visible disruption of the tamper-evident feature is necessary in order to gain access to the reclosure seal, the tamper-evident feature being fully disruptable by digital forces and including a separate reinforcing strip having respective opposing edges bonded to respective surfaces of the top portions of the respective wall panels across the width of the package so as to provide a U-shaped strip joint between the respective top portions of the wall panels, the strip having a pair of opposed tear lines, the tear lines being disposed in the reinforcing strip spaced from the opposed wall panels, such that the portion of the reinforcing strip located above the tear lines needs to be torn off in order to gain access to the reclosure seal without the necessity to tear the opposed wall panels of the package. The packages of the present invention have a unique combination of features. The packages are instore 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 has an intermediate reclosure seal which can be opened and reclosed a number of times in order to remove portions of the package contents. The reclosure seal forms a liquid-tight seal and the reclosure seal is not susceptible to interference by contact with fluids (e.g., water, juices, oils, etc.). which may be a component of the packaged product. A zipper seal consisting of interlocking closure strips is the preferred reclosure seal means. 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 Greisbach patent, the contacting surface of the two plys may be of dissimilar materials in order to produce the desired peel seal. The package of this invention further includes an outer tamper-evident feature which must be disrupted in order to gain access to the intermediate reclosure seal. The disruption of the tamper-evident feature will provide visible evidence of the fact that entry to the contents of the bag, through the intermediate reclosure seal and the inner peel seal, may have occurred. As with the package of the Hustad and Griesbach patent, the tamper-evident, reclosable and hermetically-sealed package of this invention may be made on a single machine using a straight-through process. An embodiment of the invention will now be described by way of example and with reference to the drawing. BRIEF DESCRIPTION OF THE DRAWING Fig. 1 is a plan view of a tamper-evident, reclosable, hermetically-sealed package which, when modified in accordance with figures 2 and 3, is in accordance with this invention, for purposes of illustration only, the package is shown as containing vacuum-packed wieners, Fig. 2 is a plan view of a portion of a modification of the package of Fig. 1, and Fig. 3 is a cross-sectional view taken along line 3-3 of Figure 2. In the drawing, like numerals refer to like elements. DETAILED DESCRIPTION OF AN EMBODIMENT In the description of the preferred embodiment 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 pealable bonds The peel seal should have an opening force of from 1.5 to 6.0 pounds, as discussed in the Hustad and Griesbach patent. 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. Figures 1 and 2 illustrate a package 1 formed of top and bottom bag panels 10 and 11 which enclose a plurality of wie or wiener or wiener-shaped products 12. The wieners 12 are vacuumed-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 15 of the bag may be an additional heat seal, or alternatively, 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. Alternatively, seals 13, 14 and 15 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 and spaced apart from 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 feature 44 which replaces the element 21 shown in Figure 1 and is bonded to the inner face of lips 19 and 20. As shown in Figures 2 and 3, the tamper-evident feature consists of a reinforcing strip 44 which is bonded to the top portion of each bag panel 10 and 11 so as to provide a U-shape strip joint. Bonding can be by heat sealing, adhesives or other means. The strip 44 possesses a pair of opposed tear lines 45 and 46 which will permit removal of the upper portion of the U-shaped joint by digital forces. In operation, it is necessary to sever the strip joint along lines 45 and 46 to gain access to the reclosure seal. Preferably, the reinforcing strip material is plastic and is heat sealed to the inner faces of bag panels 10 and 11. Notches 47 could be provided at the ends of tear lines 45 and 46 to facilitate tearing. Reinforcing strip 44 may extend the full width of the bag or, as shown, be somewhat shorter than bag width. While an embodiment of a package illustrating this invention has been described, it will be apparent that certain modifications and variations therefrom may be made without departing from the spirit and scope of this invention. Accordingly, only such limitations are to be imposed thereon as are indicated in the claims.

Claims: A reclosable, flexible package (1) wherein a product (12) is hermetically sealed between opposed wall panels (10, 11), the package being permanently sealed about its bottom (15) and side (13, 14) peripheries and sealed with a hermetic peel seal (16) adjacent the product towards the top of the package and having a reclosure seal comprising interlocking closure strips (17, 18) and located adjacent and peripheral to the hermetic peel seal and below the top edge of the package, characterised by a tamper-evident feature (44) located above the reclosure seal of the package, wherein visible disruption of the tamper-evident feature is necessary in order to gain access to the reclosure seal, the tamper-evident feature being fully disruptable by digital forces and including a separate reinforcing strip having respective opposing edges bonded to respective surfaces (19, 20) of the top portions of the respective wall panels (10, 11) across the width of the package so as to provide a U-shaped strip joint between the respective top portions of the wall panels, the strip having a pair of opposed tear lines (45, 46), the tear lines being disposed in the reinforcing strip spaced from the opposed wall panels, such that the portion of the reinforcing strip located above the tear lines needs to be torn off in order to gain access to the reclosure seal without the necessity to tear the opposed wall panels of the package. A package according to claim 1, wherein the respective surfaces of the top portions to which the reinforcing strip is sealed are respective inside surfaces of the respective wall panels (10, 11). A package according to claim 1 or 2, wherein the bonded reinforcing strip (44) is attached to the respective surfaces (19, 20) of the top portions by heat sealing. A package according to claim 1 or 2, wherein the bonded reinforcing strip (44) is attached to the respective surfaces (19, 20) of the top portions by an adhesive. A package according to any preceding claim, wherein the bonded reinforcing strip (44) is made of a plastics material. A package according to any preceding claim, having a notch (47) positioned at at least one end of each of the pair of opposed tear lines (45, 46).

Inventors: HUSTAD GERALD O, MARNOCHA TODD S, THOMPSON BJORN J, HUSTAD, GERALD O., MARNOCHA, TODD S., THOMPSON, BJORN J.
Applicants: MAYER OSKAR FOODS, OSCAR MAYER FOODS CORPORATION
Application year: 1990
Main classification: B65D33
IPC codes: B65D33