DIE CUT RESEALABLE LAMINATED LIDDING FILM

Abstract

A lidding film and method of manufacture thereof includes a laminated web having upper and lower film layers joined by a central PSA layer. At least one laser creates a kiss cut through one but not both of the film layers to form a first flap. A second laser can form a second, larger flap in the other film layer. Separating the film layers or pulling back the second flap also pulls back the first flap, creating an opening and leaving a PSA coated margin for resealing. One or more score cuts through only the upper layer, proximal to the apex can facilitate lifting of the flaps. A second plurality of score cuts through only the lower layer proximate but not overlapping the first plurality can further facilitate the flap lifting. The score cuts and/or printing over the die cuts can provide tamper evidence.

Claims

1. A method of manufacturing a laminated lidding film with peel back resealable flap, the method comprising: providing a laminated web comprising a first film layer on a first side of the laminated web, a second film layer on a second side of the laminated web, and a pressure sensitive adhesive (PSA) layer sandwiched between the first and second film layers, wherein the PSA layer adheres the first and second film layers to each other; causing a first laser beam directed at the first film layer from the first side of the laminated web to die cut a first flap outline through the first film layer, thereby defining a first flap formed within the first film layer of the laminate web; and causing a second laser beam directed at the second film layer from the second side of the laminated web to die cut a second flap outline through the second film layer, thereby defining a second flap formed within the second film layer of the laminate web and overlapped by the first flap; wherein: neither of the flap outlines penetrates through both of the film layers of the laminate web; and the first and second flaps are complementary in shape, but the first flap is larger than the second flap, so that the first flap extends beyond the second flap over a margin region of the second film layer of the laminate web; and separating the first flap from the first film layer at an apex of the first flap and pulling the first flap away from the laminated web causes the second flap to remain laminated to the first flap and to also be pulled away from the laminated web, so that the margin region of the second film layer is exposed, and so that an opening is formed in the lidding film in a region thereof that was formerly occupied by the second flap.

2. The method of claim 1, wherein one but not both of the flap outlines further penetrates through the PSA layer, and wherein separating the first flap from the first film layer of the laminate web a margin portion of the PSA layer remains bonded to either the margin region or to a corresponding region of the first flap.

3. The method of claim 1, wherein the first and second flap outlines are cut simultaneously.

4. The method of claim 1, wherein the first and second flap outlines are cut sequentially.

5. The method of claim 1, wherein the first and second flap outlines are cut while the web is in motion.

6. The method of claim 1, wherein the flap outline further penetrates through the PSA layer, and wherein a margin portion of the PSA layer remains bonded to either the margin region or to a corresponding region of the first film layer.

7. The method of claim 1, further comprising causing the first laser beam to further create a score cut penetrating through the first film layer but not through the second film layer of the laminate web, the score cut being located proximal to the apex of the first flap but outside of the first flap.

8. The method of claim 1, further comprising causing the first laser beam to further create a first plurality of score cuts penetrating through the first film layer but not through the second film layer of the laminate web, the first plurality of score cuts being proximal to the apex of the first flap and within the first flap.

9. The method of claim 8, further comprising causing the second laser beam to create a second plurality of score cuts penetrating through the second film layer but not through the first film layer of the laminate web, the second plurality of score cuts being proximal to but not overlapping the first plurality of score cuts.

10. The method of claim 1, further comprising: temporarily delaminating the first and second film layers of the laminate web from each other; deadening the PSA layer in a pull-tab region within the first flap and proximate the apex of the first flap; and re-laminating the first and second film layers of the laminate web to each other, whereby the pull-tab region of the first film layer remains weakly attached to or detached from the PSA layer.

11. A method of manufacturing a laminated, resealable lidding film, the method comprising: providing a laminated web comprising a first film layer on a first side of the laminated web, a second film layer on a second side of the laminated web, and a pressure sensitive adhesive (PSA) layer sandwiched between the first and second film layers and laminating the first and second film layers to each other; and causing a laser beam directed at the second film layer from the second side of the laminated web to die cut a flap outline through the second film layer without penetrating through the first film layer, thereby defining a flap formed within the second film layer that is separated from a boundary of the second film layer of the laminate web by a margin region; wherein at least partially separating the first film layer from the second film layer and pulling the first film layer partially away from the second film layer of the laminate web causes an underlying portion of the flap to remain laminated to the first film layer and to be pulled away from the margin region of the second film layer, so that an opening is formed in the lidding film in a region thereof that was formerly occupied by the underlying portion of the flap.

12. The method of claim 11, wherein the flap outline further penetrates through the PSA layer, and wherein upon separating the first film layer from the margin region a margin portion of the PSA layer remains bonded to either the margin region or to a corresponding region of the first film layer of the laminate web.

13. The method of claim 11, wherein the flap outline is cut while the web is in motion.

14. The method claim 11, further comprising: temporarily delaminating the first and second film layers of the laminate web from each other; deadening the PSA layer in a pull-tab region of the lidding film proximate a boundary of the lidding film; and re-laminating the first and second film layers to each other, whereby the first and second film layers remain weakly attached to each other or are detached from each other in the pull-tab region.

15. A laminated lidding film with peel back resealable flap, comprising: a first film layer on a first side of the laminated lidding film; a second film layer on a second side of the laminated lidding film; a pressure sensitive adhesive (PSA) layer sandwiched between the first and second film layers and laminating the first and second film layers to each other; a first flap outline die cut through the first film layer of the laminated lidding film and defining a first flap formed within the first film layer; and a second flap outline die cut through the second film layer of the laminated lidding film and defining a second flap formed within the second film layer of the laminated lidding film and overlapped by the first flap; wherein: the first and second flaps are complementary in shape, but the first flap is larger than the second flap, so that the first flap extends beyond the second flap over a margin region of the second film layer; and separating the first flap from the first film layer of the laminated lidding film at an apex of the first flap and pulling the first flap away from the laminated web causes the second flap to remain laminated to the first flap and to also be pulled away from the laminated web, so that the margin region of the second film layer is exposed, and so that an opening is formed in the lidding film in a region thereof that was formerly occupied by the second flap.

16. The film of claim 15, wherein one but not both of the flap outlines further penetrates through the PSA layer, and wherein upon separating the first flap from the first film layer of the laminated lidding film a margin portion of the PSA layer remains bonded to either the margin region or to a corresponding region of the first flap.

17. The film of claim 15, further comprising a score cut penetrating the first film layer of the laminate lidding film but not the second film layer, the score cut being located proximal to the apex of the first flap but outside of the first flap.

18. The film of claim 15, further comprising a first plurality of score cuts penetrating the first film layer but not the second film layer, the score cuts being proximal to the apex of the first flap and within the first flap.

19. The film of claim 18, further comprising a second plurality of score cuts penetrating the second film layer of the laminated lidding film but not the first film layer, the second plurality of score cuts being proximal to but not overlapping the first plurality of score cuts.

20. A laminated lidding film with peel back resealable flap, comprising: a first film layer on a first side of the laminated lidding film; a second film layer on a second side of the laminated lidding film; a pressure sensitive adhesive (PSA) layer sandwiched between the first and second film layers and laminating the first and second film layers to each other; and a flap outline die cut through the second film layer of the laminated lidding film but not through the first film layer and defining a flap formed within the second film layer that is separated from a boundary of the second film layer by a margin region; wherein at least partially separating the first film layer of the laminated lidding film from the second film layer of the laminated lidding film and pulling the first film layer partially away from the second film layer causes an underlying portion of the flap to remain laminated to the first film layer and to be pulled away from the margin region of the second film layer, so that an opening is formed in the lidding film in a region thereof that was formerly occupied by the underlying portion of the flap.

21. The film of claim 20, wherein the flap outline further penetrates through the PSA layer, and wherein upon separating the first film layer of the laminated lidding film from the margin region a margin portion of the PSA layer remains bonded to either the margin region or to a corresponding region of the first film layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG. 1 is a photograph of a prior art food package, shown in an open configuration;

[0040] FIG. 2 is a cross-sectional side view of a 2-laser die-cut embodiment of the invention showing the upper and lower lasers, the film layers, and the die cuts;

[0041] FIG. 3A is a top view of a 2-laser die-cut embodiment of the invention, shown with the flap closed;

[0042] FIG. 3B is a top view of the embodiment of FIG. 3A, shown with the flap open;

[0043] FIG. 4 is a top view of a 2-laser die-cut embodiment that includes a printed graphic and pull tab;

[0044] FIG. 5 is a top view of a 2-laser die-cut embodiment that includes an outer score cut and pull tab region;

[0045] FIG. 6 is a close-up top view of the flap apex region of a 2-laser die-cut embodiment showing a plurality of score cuts located between the apexes of the upper and lower flaps;

[0046] FIG. 7 is a cross-sectional side view of a 1-laser die-cut embodiment of the invention showing the lower laser, the film layers, and the die cut;

[0047] FIG. 8A is a top view of a 1-laser die-cut embodiment of the invention heat-sealed to a plastic tray, shown with the flap closed;

[0048] FIG. 8B is a top view of the embodiment of FIG. 8A, shown with the flap open;

[0049] FIG. 9A is a perspective view of a container with contents that is sealed by a 1-laser die-cut laminate lidding film according to an embodiment of the present invention;

[0050] FIG. 9B is a perspective view of the container of FIG. 9A shown with a small region of the lidding film pulled back from the container flange;

[0051] FIG. 9C is a perspective view of the container of FIG. 9A shown with a larger region of the lidding film pulled back from the container flange;

[0052] FIG. 9D is a perspective view of the container of FIG. 9A shown during re-sealing of the lidding film;

[0053] FIG. 9E is a perspective view of the container of FIG. 9A shown after the lidding film has been re-sealed; and

[0054] FIG. 9F is a perspective view of the container of FIG. 9A shown tipped over to demonstrate that the re-sealed lidding film is not detached when the contents of the container are gravitationally pressed against it.

DETAILED DESCRIPTION

[0055] The present invention is a lidding film and method of manufacture thereof that provides for peel-back opening and substantially hermetic resealing of the package, without requiring a multiple step manufacturing process, during which printing of text and graphics onto the lidding film without misalignment is unrestricted and unimpeded.

[0056] With reference to FIG. 2, instead of requiring that two film structures be separately prepared, printed, cut, and then assembled together, the method of manufacture of the present invention includes preparing a laminated web 200 having upper 202 and lower 204 layers of a packaging material such as PET (polyethylene terephthalate), with a pressure sensitive adhesive (PSA) included as a middle layer 206 therebetween. Depending on the embodiment, either one laser 214 or a pair of lasers 208, 214 are used to make cuts (kiss-cuts) into the web 200 from either or both sides, wherein each laser 208, 214 cuts only through one of the laminated films 202, 204, before the kiss-cut web (which has the kiss-cut design repeated along the web) is formed into a roll of lidding film to be used for heat-sealing to individual trays.

[0057] According to the present method, the laser powers and pulse times are adjusted to kiss-cut the laminate web 200, whereby a lower laser 214 cuts only through the lower film layer 204. In the 2-laser embodiment of FIG. 2, a second upper laser 208 cuts only through the upper film layer 202. It will be understood that the terms upper and lower are used herein only to refer to the two opposing sides of the laminate 200, and that the lower laser 214 may, for example, be physically above the laminate 200, or in other embodiments the laminate 200 may be vertically oriented and the lower laser 214 may be located to one side.

[0058] Depending on the embodiment, the lower laser 214, or either of the upper 208 and/or lower 214 lasers (as shown in FIG. 2), may penetrate into or through the PSA layer 206, but neither laser cuts through both of the upper 202 and lower 204 film layers. In the embodiment of FIG. 2, the upper kiss-cut 210 extends through the PSA layer 206, while the lower cut 212 does not. Neither of the cuts 210, 212 extends through both of the film layers 202, 204. In embodiments, the cuts 210, 212 are formed while the laminate web 200 is in motion 216.

[0059] According to the present method, the laser powers and pulse times are adjusted to kiss-cut the laminate web 200, whereby one of the lasers 208 (for convenience referred to herein as the upper laser) cuts 210 only through the upper film layer 202 while the other (lower) laser cuts 212 only through the lower film layer. One but not both of the upper 208 and lower 214 lasers further cuts through the PSA layer 206. In the embodiment of FIG. 2, the upper cut 210 extends through the PSA layer 206, while the lower cut 212 does not. Neither of the cuts 210, 212 extends through both of the film layers 202, 204. In embodiments, the cuts 210, 212 are formed simultaneously or sequentially while the laminate web 200 is in motion 216.

[0060] FIGS. 3A and 3B are top views of a 2-laser die-cut embodiment of the present invention. While the materials are often transparent, the upper film layer 202 has been shaded in the figure to make it visible. It can be seen in FIG. 3A that the upper 210 and lower 212 kiss cuts form upper 302 and lower 304 flaps that are similar in shape. However, the upper flap 302 is larger than the lower flap 304, so that the cuts 210, 212 are separated by a margin 300 and do not overlap.

[0061] FIG. 3B illustrates the embodiment of FIG. 3A with the flaps 302, 304 pulled away from the lid film 200, leaving a large opening 306 through which contents of the package (not shown) can be accessed. In the illustrated embodiment, the upper cut 210 penetrates both the upper film layer 202 and the PSA layer 206, such that the adhesive 206 from the margin region 300 remains attached to the upper flap 302. In similar embodiments, the lower cut 212 penetrates the PSA layer 206, instead of the upper cut 210, so that the PSA in the margin 300 remains attached to the lower layer 204 when the flaps 302, 304 are pulled away from the lid film 200.

[0062] The flaps 302, 304 in the lidding film are opened by grasping an apex of the upper flap 302 and peeling the upper flap 302 away from the package, thereby drawing with it the smaller, lower flap 304, and leaving behind an opening 304 that is surrounded by an exposed margin 300 of the lower layer.

[0063] In various embodiments, such as the embodiment of FIGS. 3A and 3B, the user uses finger-nails etc. to peel up a small portion of the apex of the upper flap 302 away from the lower film layer, and then proceeds to pull the flaps 302, 304 upwards (the lower flap 304 remaining attached to the upper flap 302), so as to open the package. In practice, light refraction from the die cuts within the transparent lidding film can cause the location of the upper cut 210 to be visible, as shown on the right side of FIG. 3B.

[0064] With reference to FIG. 4, in various embodiments printing of text and/or graphics is applied to the web 200 before the laser die cutting. Because the films and PSA layers are pre-laminated as a web, the die cutting does not lead to any misalignment of the text and/or graphics.

[0065] With reference to FIGS. 4 and 5, in some embodiments, before the die cutting step, the lidding film 200 is de-laminated, and the PSA in a pull-tab region 400 at the apex of the upper cut 210 is deadened, before re-laminating the film 200. With this approach, once the film in die cut around the tab area along with die cutting to produce the flaps, the pull-tab region 400 can be easily detached from the lower film layer 204 and grasped to pull the flaps 300 away from the lower film layer 204.

[0066] In still other embodiments, one or more short score cuts are provided near the apex of the upper flap 302 to render the flap easier to grasp. None of the score cuts penetrates through both of the upper 202 and lower 204 film layers. In some of these embodiments, as illustrated in FIG. 5, at least one outer score cut 500 is made in the upper film layer 202 parallel to and just above the apex of the upper cut 210, so that a user's fingernail can more easily be inserted under the upper flap. In other embodiments, with reference to FIG. 6, instead of or in addition to this at least one outer score cut 500, a plurality of inner score cuts 600 are provided in a region spanning between the apexes of the upper flap 302 and lower flap 304. By essentially scratching this scored region 600 of the upper film layer 202, plastic material is drawn away from the PSA 206 and lower laminate 204 layers, so that the apex of the upper flap 302 can be more easily grasped.

[0067] In still other embodiments, upper and lower pluralities of non-overlapping score cuts 600 are provided in both the upper and lower film layers in the region spanning between the apexes of the upper 302 and lower 304 flaps. The locations of the upper and lower score cuts 600 are offset, so that none of the upper score cuts intersects any of the lower score cuts. While the lidding film 200 remains sealed, these upper and lower score cuts 600 provide a weakened region between the apexes of the flaps 302, 304 that can be penetrated by a user's finger, so as to grasp the apexes of the flaps 302, 304 and pull the flaps 302, 304 away from the lidding film 200. These embodiments are suitable, for example, for applications where a small remaining penetration of the package after resealing can be tolerated by the consumer after opening the package.

[0068] It should be noted that embodiments with score cuts 500, 600 further provide visible evidence of previous opening of the package due to damage of the score cuts 500, 600, thereby providing tamper evidence. Tamper evidence can also be provided in various embodiments by printing of text, patterns, or graphics across the upper cut 210, so that opening and closing of the flap inevitably leads to a perceptible misalignment of the text, pattern, or graphic at the upper score cut 210.

[0069] FIG. 7 is a cross-sectional side view of an apparatus used to manufacture the lidding film of the present invention in a 1-laser die-cut embodiment. As in the embodiment of FIG. 2, the laminated web 200 includes upper 202 and lower 204 layers of a packaging material such as PET (polyethylene terephthalate), with a pressure sensitive adhesive (PSA) included as a middle layer 206 therebetween. In the illustrated embodiment, a single lower laser 214 is used to make cuts 212 from below, wherein the laser 214 cuts only through the lower laminated sheet 204, before the kiss-cut web is wound into a roll of film and used as a lidding film to seal individual plastic trays.

[0070] The laser power and pulse times are adjusted to kiss-cut the laminate web 200, so that the lower laser 214 cuts only through the lower film layer 204, while the upper layer 202 remains uncut. It will be understood that the terms upper and lower are used herein only to refer to the two opposing sides of the laminate 200, and that the lower laser 214 may, for example, be physically above the laminate 200, or in other embodiments the laminate 200 may be vertically oriented and the lower laser 214 may be located to one side.

[0071] FIGS. 8A and 8B are top views of a lidding film according to a 1-laser die-cut embodiment of the present invention. While the materials are often transparent, the upper film layer 202 has been shaded in the figure to make it visible. It can be seen in FIG. 8A that the lower 212 kiss cut defines a lower region that is separated from the outer boundary of the lidding film 200 by a margin 300.

[0072] FIG. 8B illustrates the embodiment of FIG. 8A with a corner of the upper layer 202 pulled away from the lower layer 204, leaving a large opening 306 through which contents of the package (not shown) can be accessed. In the illustrated embodiment, the lower cut 212 does not penetrate the PSA layer 206, such that the adhesive 206 from the margin region 300 remains attached to the upper layer 202. In similar embodiments, the lower cut 212 penetrates the PSA layer 206, so that the PSA in the margin 300 remains attached to the lower layer 204 when the flaps 302, 304 are pulled away from the lid film 200.

[0073] In the embodiment of FIGS. 8A and 8B the upper layer 202 of the lidding film 200 can be separated from the lower layer 204 by pulling back a portion of the excess film that remains on the plastic tray flange after the die-cut film is heat-sealed to the tray. Essentially, the consumer de-laminates the upper layer of film 202, and in doing so an opening is created in the package where the die cut was made in the lower layer 204. As the upper layer 202 is then pealed back from the lower layer 204, the margin 300 of the lower layer remains attached to the container while the lower flap 304 remains attached to the upper layer 202 and is separated from the margin 300 of the lower layer 204.

[0074] FIG. 9A is a perspective view of a container filled with contents and sealed by a lidding film according to a 1-laser die-cut embodiment of the present invention. FIG. 9B is a perspective view of the container of FIG. 9A shown with a small region of the lidding film pulled back from the container flange, while FIG. 9C is a perspective view of the container of FIG. 9A shown with a larger region of the lidding film pulled back from the container flange. FIG. 9D illustrates re-sealing of the lidding film of FIG. 9A, while FIG. 9E is a perspective view of the container of FIG. 9A shown after the lidding film has been re-sealed. As can be seen in FIG. 9F, where the container of FIG. 9A is shown in a partially inverted orientation, in embodiments the adhesive attachment of the lidding film to the container is sufficient, even after resealing, to prevent the lidding film from being detached when the contents of the container are gravitationally pressed against it.

[0075] The foregoing description of the embodiments of the invention has been presented for the purposes of illustration and description. Each and every page of this submission, and all contents thereon, however characterized, identified, or numbered, is considered a substantive part of this application for all purposes, irrespective of form or placement within the application. This specification is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of this disclosure.

[0076] Although the present application is shown in a limited number of forms, the scope of the invention is not limited to just these forms, but is amenable to various changes and modifications without departing from the spirit thereof. The disclosure presented herein does not explicitly disclose all possible combinations of features that fall within the scope of the invention. The features disclosed herein for the various embodiments can generally be interchanged and combined into any combinations that are not self-contradictory without departing from the scope of the invention. In particular, the limitations presented in dependent claims below can be combined with their corresponding independent claims in any number and in any order without departing from the scope of this disclosure, unless the dependent claims are logically incompatible with each other.