Tubular container with release strip

Abstract: A release strip (13) for tubular containers (10) is provided and includes a tab portion (16). An elongate portion (15) of the release strip is releasably adhered to an outer surface of the tubular body of the container with a first adhesive application (20). The tab portion extends laterally from the elongate portion and is separately releasably adhered to the tubular body with a second adhesive application (21) to prevent the tab portion from being inadvertently snagged. In one preferred embodiment, the tab portion includes an opening (17) therein having an advantageous shape including an arcuate section (24) having at least a predetermined minimum radius of curvature and a substantially straight section (25) opposite the arcuate section, thus allowing sufficient room for accommodating a consumer's finger while maintaining requisite ring strength. An apparatus (30) for manufacturing and applying the release strips also forms a part of the invention and includes first and second adhesive applicators (40, 41) which are offset to apply the first adhesive application to the elongate portion of the release strip and the second adhesive application to the tab portion.

Description: FIELD OF THE INVENTION The invention relates to tubular containers, and more particularly relates to release strips for removably maintaining end closures on tubular containers. BACKGROUND OF THE INVENTION Food products and other perishable items are often packaged using tubular containers which are sealed at both ends. The tubular containers typically include at least one structural body ply, which is advantageously formed of paperboard, a liner ply on the inner surface of the body ply to provide an impervious barrier to liquids, moisture and some or all gasses, and a label ply around the outside of the body ply for designating the product packaged therein. End closures are applied on both ends to enclose the container. At least one of the ends is preferably provided with a release strip which allows quick and easy opening of the tubular container by the consumer. These release strips may take several forms, although a common configuration is a release strip which is wrapped around one end of the tubular container before the respective end closure is applied. The end closure is then placed over the end adjacent to the release strip and a generally radially projecting flange of the closure is bent towards the outer surface of the tubular container so as to engage firmly the release strip between the outer surface of the tubular container and the flange. A tab portion is typically provided at one end of the release strip so that a consumer can pull the tab portion and the release strip will be disengaged from between the flange of the end closure and the outer surface of the tubular container. Accordingly, a clearance will be provided between the end closure and the tubular container, and the end closure can then easily be removed. A typical apparatus for securing release strips to tubular container bodies is disclosed in U.S. Patent No. 3,690,997 to Bofinger, et al. A roll of plastic web material for the strips is unwound and fed to a cutting member which forms the individual strips. The strips are then advanced in a direction perpendicular to the feed direction of the plastic web material to a vacuum wheel where one entire surface of the strip (having a substantially constant width) is engaged against the peripheral surface of the vacuum wheel. An adhesive is applied to the opposite surface of the release strip by an adhesive roll. An applicator turret rotates the tubular containers against the release strip surface to adhere the release strips to the tubular containers. The adhesive applicator roll is provided with a narrow annular peripheral extension which applies a single adhesive band along ·the full longitudinal length of the strip including the tab in an area which is disposed adjacent that edge of the strip which is to be farthest removed from the adjacent edge of the tubular body to which the strip will be applied. In one embodiment, the tab is provided with a circular hole which, when adhered to the container, overlies the opposite end of the release strip. A similar release strip configuration is illustrated in U.S. Design Patent No. 208,222 to Slomski. One disadvantage of these container types, however, is that the tab portion provides a limited area for allowing the consumer to initiate and continue removal of the release strip. It is possible for the tab to slip from the grasp of the consumer when pulling on the tab portion. In addition, it has been determined that it is easier to open containers if the tab portion can be twisted relative to the remainder of the release strip during removal thereof. However, the release strips of the prior art have a substantially constant width in the circumferential direction making twisting of the tab portion during removal difficult. An alternative configuration is disclosed in U.S. Patent No. 3,409,200 to Balocca et al, wherein a release strip is provided having a slightly enlarged pull tab extending in a direction away from the end closure. An adhesive for adhering the elongate portion of the release strip may be extended to cover the tab and adhere the tab to the container body. This tab configuration may also not provide a sufficiently graspable area to allow the release strip to be easily removed and the tab of this design can also slip from the grasp of the consumer. If the size of the tab is increased to facilitate better grasping, additional adhesive is required to adhere the enlarged tab to the tubular container, thus adding to the expense of the container. Conversely, if the end portion of an enlarged tab is not adhered to the container, the free end of the tab can become accidentally snagged during the manufacture or subsequent handling of the container such that part of the release strip may be prematurely removed. One attempt to solve the problem of outwardly extending tabs during handling is disclosed in U.S. Patent No. 3,330,436 to Slomski. An adhesive bond is provided between the inside surface of the tab and the subjacent tubular container surface and is in alignment with the adhesive band on the elongate portion of the release strip. However, the container of this patent also suffers from having a small tab which can be difficult to grasp. Accordingly, there is a need for a release strip having an easily engaged tab which facilitates removal and eliminates or greatly reduces slipping of the tab from the grasp of the consumer. Such a release strip preferably would not extend outwardly so as to damage or cause partial premature removal of the release strip during handling of the container. The present invention is set forth in claim 1 hereto. The preamble of claim 1 corresponds to the disclosure of US3409200A. In particular, one aspect of the invention is a tubular container having a release strip with an opening in the tab portion which is large enough to receive and be engaged by the finger of a consumer, thus providing improved removability of the release strip. An advantageous shape for the opening includes an arcuate section to receive the finger of the consumer and an opposite straight section which decreases the extent to which the tab position extends from the end closure and increases the bonding area for the adhesive. Other embodiments of release strips include reduced neck portions adjacent the tab portion to allow twisting of the tab portion during removal of the release strip. More particularly, the tubular container includes a tubular body having axially opposed ends and inner and outer surfaces, and an end closure adjacent at least one of the ends of the tubular body. The end closure has a flange positioned in spaced adjacency with the outer surface of the tubular body and adjacent to the end. A release strip is removably engaged between the flange and the outer surface of the tubular body. In particular, the release strip includes an elongate portion which is engaged between the flange and the tubular body so that the flange will be released from the tubular body when the release strip is removed. The tab portion of the release strip defines an opening having a sufficient dimension to accommodate a finger of a user therethrough and having a predetermined shape. The predetermined shape of the opening includes an engagement edge opposite from the elongate portion over which the finger of the consumer is inserted and engaged for easily and efficiently removing the release strip from between the end closure and the tubular body. In particular, the shape preferably includes an arcuate section and a substantially straight section opposite the arcuate section. The arcuate section advantageously has a predetermined minimum radius of curvature which is preferably about 8.25 mm (0.325 inches), to allow a finger of an average consumer to be engaged in the opening and against the arcuate section. The straight section is aligned in a circumferential direction with one side edge of the release strip so that a substantially constant minimum width is provided for the release strip through both the elongate portion and the tab portion. As a result of this advantageous shape, the opening has a sufficient radius to accommodate a consumer's finger to allow easy removal of the release strip, but also prevents the tab from disadvantageously weakening the ring shaped tab portion adjacent to the end closure or extending outwardly too far from the end closure. The elongate portion of the release strip is releasably adhered to the outer surface of the tubular body with a first area of adhesive. The tab portion extends laterally from the elongate portion and is separately releasably adhered to the tubular body with a second area of adhesive, thus preventing the tab portion from becoming snagged during manufacture and shipment of the tubular container. A third area of adhesive between the first and second areas of adhesive further adheres the tab portion to the outer surface of the tubular body. BRIEF DESCRIPTION OF THE DRAWINGS Some of the objects and advantages of the invention have been set forth and other objects and advantages of the invention will become apparent in the detailed description of the preferred embodiments of the invention to follow, when taken in conjunction with the accompanying drawings, which are not necessarily drawn to scale: Figure 1 is a perspective view of a tubular container according to the present invention; Figure 2 is a plan view of the release strip used in the Figure 1 container illustrating the placement of first and second areas of adhesive; Figure 3 is a plan view of the opposite side of the release strip illustrated in Figure 2; Figure 4 is an enlarged sectional view of the release strip and an end closure of the tubular container taken along lines 4-4 of Figure 1; Figure 5 is an enlarged perspective view of a portion of the tubular container illustrating the removal of the release strip; Figure 6 is a partial sectional view of the release strip taken along lines 6-6 of Figure 1; Figure 7 is a perspective view of an apparatus for applying the release strips to tubular containers; Figure 8 is a partial sectional view of first and second adhesive applicators taken along lines 8-8 of Figure 7; Figure 9 is a greatly enlarged plan view of a portion of a release strip provided with three areas of adhesive; Figure 10 is a greatly enlarged plan view of a portion of a release strip illustrating a pliable engagement portion of the tab portion adjacent to the opening therein; Figure 11 is a perspective view of a portion of the tubular container illustrating the removal of the release strip of Figure 10; Figure 12 is a sectional view of the release strip taken along line 16-16 of Figure 10; Figure 13 is a sectional view of the release strip illustrating how the pliable engagement portion of the tab portion bends when the release strip is engaged by .the finger of a consumer; Figure 14 is a plan view of a release strip having a different embodiment of the pliable engagement portion; Figure 15 is a plan view of a release strip having a different embodiment of the pliable engagement portion; and Figure 16 is a plan view of a release strip having another embodiment of the pliable engagement portion. DETAILED DESCRIPTION OF THE EMBODIMENTS Various embodiments relating to the invention are set forth below. While the invention is described with reference to specific preferred embodiments, including those illustrated in the drawings, it will be understood that the invention is not intended to be so limited. To the contrary, the invention includes numerous alternatives, modifications, and equivalents as will become apparent from consideration of the present specification including the drawings, the foregoing discussion, and the following detailed description. The tubular container 10 according to the present invention is illustrated in Figure 1 and includes a tubular body 11 , an end closure 12 and a release strip 13 . The tubular body 11 is preferably formed from paperboard and can have one or more structural body plies. The tubular body 11 may also include a liner ply on the inner surface of the body ply to provide an impervious barrier to liquids, moisture and gasses and a label ply around the outside of the body ply for designating the product packaged therein. An end closure 12 can be fitted at one or both ends of the tubular body 11 . The end closure 12 is preferably formed of metal and includes a flange 14 which extends over the end of the tubular body 11 . The flange 14 includes one or more bends therein to create a seamed end closure 12 which is frictionally engaged to the tubular body 11 . In particular, the flange 14 is bent over to engage the release strip 13 against the tubular body 11 , as can be seen in Figure 4. The end closure 12 can thus be removed from the body 11 by first removing the release strip 13 . The release strip 13 is shown in more detail in Figures 2 and 3 and includes an elongate portion 15 and a tab portion 16 . As can be seen in Figures 2 and 4, a first area of adhesive 20 is provided along the length of the elongate portion 15 of the release strip 13 . The first area of adhesive 20 may be substantially continuous as shown or comprise intermittent segments of adhesive along the length of the release strip 13 . The first area of adhesive 20 thus adheres the release strip 13 to the end of the tubular body 11 before the end closure 12 is applied, as discussed in more detail below. A second area of adhesive 21 which is spaced in the axial direction of the container 10 from the first area of adhesive 20 . The tab portion 16 extends laterally from the elongate portion 15 by a distance which allows adequate grasping of the tab portion by a consumer. In particular, a distal section 22 of the ring shaped tab portion 16 may extend one inch or more from the elongate portion 15 , which provides enhanced graspability for the consumer. Without the second area of adhesive 21 , such an enlarged tab portion 16 could become snagged during manufacture and handling (either on the machinery or with an adjacent can). Snagging can be detrimental to the release strip 13 and/or the container 10 and can cause costly and inefficient manufacturing delays. The second area of adhesive 21 causes the distal arcuate section 22 to be releasably adhered to the tubular body 11 and prevents the tab portion 16 from being snagged. Furthermore as is explained with reference to Figures 5 to 9 a third area of adhesive 44 is provided between the first and second areas of adhesive 20 , 21 . The tubular container 10 is opened in the manner illustrated in Figure 5. Specifically, the consumer first places a finger through the ring shaped tab portion 16 of the release strip 13 . The tab portion 16 defines an opening 17 having a sufficiently large dimension to accommodate a finger of a consumer therethrough. The opening 17 preferably has a predetermined shape which includes. an engagement edge 18 . The finger of the consumer is inserted in the opening 17 over the engagement edge 18 and then pulled against the engagement edge for removing the release strip 13 . The consumer continues to pull the tab portion 16 to disengage the elongate portion 15 of the release strip 13 from between the flange 14 and the tubular body 11 . Once the release strip 13 has been fully removed, it will be appreciated that a space is created between the flange 14 and the tubular body 11 . Accordingly, the end closure 12 can be easily removed from the end of the tubular body 11 and the contents of the container 10 can be removed from that end of the container. The opening 17 can be of any size and shape which facilitates insertion and engagement by a finger although one particularly advantageous shape can be seen in Figures 2 and 3. The tab portion 16 includes the distal section 22 and opposite side sections 23a,23b . The opening 17 in the tab portion 16 includes an arcuate section 24 and a substantially straight section 25 opposite the arcuate section. The arcuate section 24 preferably has a predetermined minimum radius of curvature which is preferably constant throughout for accommodating a finger of an average consumer. It has been determined that a constant radius of between about 6.5 mm and 13 mm (0.25 inches and 0.50 inches), and more particularly about 8.25 mm (0.325 inches), is a suitable radius. The release strip 13 includes first and second side edges 26,27 which are parallel to each other and, when adhered to the container 10 , are offset in the direction of the axis of the container. The straight section 25 of the opening in the ring shaped tab portion 16 and the second side edge 27 are advantageously aligned (in a circumferential direction relative to their positions on the container 10 ) so that the release strip 13 has a predetermined minimum width along substantially the entire length of the release strip 13 . The straight section 25 enhances the strength of the ring shaped tab portion 16 and provides an increased bonding surface area which corresponds to the underlying opposite end of the release strip 13 . In addition, the straight section 25 allows the opening 17 to have an arcuate section 24 of a certain predetermined minimum radius of curvature without causing the tab portion 16 to extend as far as it would if the opening was a complete circle of the same radius. The outer contour of the release strip 13 includes a generally convex arcuate section 28 extending around the ring shaped tab portion 16 . The outer contour also includes a concave arcuate section 29 which blends the convex arcuate section 28 into the second side edge 27 of the elongate portion 15 to prevent tearing of the release strip 13 . Thus, the preferred shape of the opening of the ring shaped tab portion 16 successfully balances certain design considerations to create a highly advantageous release strip. The arcuate section 24 has a predetermined minimum radius which has been determined to suitably accommodate the finger of an average consumer but which does not extend too far from the end closure 12 in the axial direction of the container 10. As would be appreciated, however, other opening shapes could be used including complete circles, ovals, ellipses or any other shapes which could accommodate the finger of a consumer. The release strip 13 preferably has a thickness of at least about 0.4 mm (0.015 inches), which has been determined to be thick enough to present little risk of cutting a consumer's finger, although other thicknesses may be used depending upon the specific application. A related advantageous feature is illustrated in Figures 10-16 wherein the engagement edge 18 defines an edge of a pliable engagement portion 19 extending at least partially from the distal section 22 . Advantageously, the engagement portion 19 is pliable and bends in the manner illustrated in Figures 11 and 13 when a finger of the consumer is engaged against the engagement edge 18 . The bending of the pliable engagement portion 19 provides a greater surface area for engagement with the finger and ensures that the engagement edge 18 does not cut the finger of the consumer. The embodiment of the pliable engagement portion 19 illustrated in Figures 10-13 includes an arcuate groove 51 or score which reduces the thickness of the release strip 13 and increases the flexibility along that groove 51 . The embodiment of Figure 14 includes a pair of arcuate cuts 52 which define the pliable engagement portion 19 . The embodiment of Figure 15 includes a pliable protrusion 53 extending from the distal section 22 of the tab portion 16. The embodiment of Figure 16 includes a pliable engagement portion 19 extending outwardly from the distal section 22 and a plurality of slits 54 for reducing the stiffness of the material and increasing the pliability. Various other ways of forming a pliable engagement portion 19 would be apparent to one of ordinary skill in the art including coining or pressing part of the release strip 13 adjacent the engagement edge 18 to reduce the original thickness of the material. An apparatus 30 and method for forming and applying release strips 13 is illustrated in Figures 7 and 8. The apparatus includes many components which are common with the apparatus disclosed in U.S. Patent No. 3,690,997 to Bofinger, et al. (which is incorporated herein by reference) but also includes several modifications which provide advantages over the conventional apparatus. The apparatus includes a supply source of a continuous web of release strip material 31 . It has been determined that a suitable release strip material 31 is high density polyethylene (HDPE) although other materials could be used, such as polyester or other suitable polymers and laminates thereof. The release strip material 31 is advanced in a feed direction by servo driven feed rollers 38 to a punch press 32, which forms the individual release strips 13. Preferably, the punch press 32 includes a plurality of progressive dies 33a,33b for forming the advantageous shape of the release strip 13 according to the invention. To enhance the operation of the progressive dies 33a,33b , the release strips 13 may include various small offsets 39 in the outer contour. A pusher bar 34 advances the individual release strips in an end-to-end relationship to a vacuum wheel 35 along a predetermined path of travel. The feed direction of the web material 31 is preferably offset from the path of travel of the release strips 13 by an obtuse angle α. The obtuse angle α is preferable to prior apparatus where the web material 31 was fed perpendicularly to the release strips 13 because it allows the release strips to be formed from a narrower web of material without excessive scrap being generated. In particular, the angled approach for the web material 31 allows the release strips 13 to be efficiently nested, even though the release strips include generally large tab portions 16 . The nesting can be seen in Figure 7 and allows the punch press 32 to create both the trailing edge of the elongate portion of one release strip and the leading edge of the elongate portion of the next successive release strip with a single cut and minimal scrap. Increasing the obtuse angle α generally increases the size of the tab portion 16 which can be made while still maintaining the nestability of the release strips 13 . It has been determined that an obtuse angle α of at least about 135° is preferred, and more particularly an angle α of about 158°. The vacuum wheel 35 includes a peripheral surface 36 defining a plurality of vacuum openings 37 therein, each of which is connected to a vacuum source. Accordingly, the elongate portions 15 of the release strips 13 are releasably held against the peripheral surface 36 by the vacuum openings 37 . The laterally extending tab portions 16 preferably extend laterally in an axial direction beyond the edge of the peripheral surface 36 of the vacuum wheel 35 , as can be seen in Figure 8. A first adhesive applicator 40 is positioned adjacent to the peripheral surface 36 of the vacuum wheel 35 for applying adhesive along the elongate portions 15 of the release strips 13 as the strips pass the applicator. As noted above, the first area of adhesive 20 can be substantially continuous along the length of the release strip 13 or can be comprised of a succession of intermittent segments. Advantageously, a second adhesive applicator 41 is provided at a position which is offset in the direction of the axis of the vacuum wheel 35 from the first adhesive applicator 40 . As shown in Figure 7, the adhesive applicators 40,41 may also be offset in a circumferential direction relative to the vacuum wheel 35. The second adhesive applicator 41 is preferably an adhesive gun which is triggered as the release strips 13 pass thereunder so that adhesive is intermittently released onto the tab portion 16 . In this fashion, only a minor amount of additional adhesive for the second area of adhesive 21 is required. After the first and second adhesive applicators 40,41, the strips are passed to a carrier wheel 42 which carries a succession of tubular container bodies 11 in a tangent relationship to the release strips 13 on the vacuum wheel 35 . The container bodies 11 are rotated against the release strips 13 so that each release strip will be adhered to one end of a respective tubular body 11 . From the carrier wheel 42 , the tubular bodies and adhered release strips 13 are advanced to a conventional seaming apparatus for applying end closures 12 over the release strip 13 of each tubular body 11. The container 10 is then filled with product and the opposite end of the container is sealed with a suitable end closure. With reference to Figure 6, the first and second areas of adhesive 20,21 , in combination with the stiffness of the release strip material, cause a side section 23a of the release strip to extend slightly outwardly from the cylindrical surface of the body 11 so as to create a slight separation 43 from the body. Separation 43 is not desirable, and a third area of adhesive 44 is applied to the side sections 23a,23b of the tab portion 16 between the first and second areas of adhesive 20,21 , as shown in Figure 9, by a third adhesive applicator 45, as shown in Figure 8. The third area of adhesive 44 ensures substantial conformity of the tab portion 16 with the cylindrical outer surface of the tubular body 11 . Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims: A tubular container (10) comprising: a tubular body (11) having axially opposed ends and inner and outer surfaces; an end closure ( 12) adjacent at least one of the ends of said tubular body and having a flange (14) positioned in spaced adjacency with the outer surface of said tubular body adjacent to said one end; and a release strip (13) removably engaged between said flange (14) and the outer surface of said tubular body (11) so that said flange (14) will be released from said tubular body (11) when said release strip (13) is removed, said release strip (13) having an elongate portion (15) which is engaged between said flange (14) and said tubular body (11) and a tab portion (16) extending laterally from said elongate portion (15) generally adjacent to said tubular body (11), wherein said elongate portion (15) is releasably adhered to the outer surface of said tubular body (11) with a first area of adhesive (20) between said elongate portion (15) and said tubular body, characterised in that said tab portion (16) is generally ring shaped and defines an opening (17) having a sufficient dimension to accommodate a finger of a consumer therethrough and includes an engagement edge (18) opposite from said elongate portion (15) over which the finger of the consumer is inserted and engaged for removing said release strip (13) from between said end closure (12) and said tubular body (11), said tab portion (16) being separately releasably adhered to said tubular body (11) with a second area of adhesive (21) between said tab portion (16) and said tubular body (11), and further characterised in that said tab portion (16) comprises a distal section (22) spaced from said elongate portion (15), and opposite side sections (23a, 23b) between said distal section (22) and said elongate portion (15), each of said opposite side sections (23a, 23b)being adhered to the outer surface of said tubular body (11) by third areas of adhesive (44). A tubular container as defined in Claim 1 wherein said engagement edge defines an edge of a pliable engagement portion (19) extending from said distal section. A tubular container as defined in Claim 1 wherein the tab portion includes a substantially straight section (25) adjacent to said elongate portion and an opposite arcuate section (24) having a predetermined minimum radius of curvature. A tubular container as defined in Claim 3 wherein said elongate portion of said release strip has a first side edge (26) adjacent said one end of said tubular body and a second side edge (27) axially offset from said first side edge, and wherein said straight section of the opening in said tab portion is aligned in a circumferential direction with said second side edge of said release strip. A tubular container as defined in Claim 3 wherein said arcuate section of the opening of said tab portion has a constant radius of curvature of between about 6.5 mm and about 13 mm (0.25 inches and 0.5 inches). A tubular container as defined in Claim 5 wherein said arcuate section of the opening of said tab portion has a constant radius of curvature of about 8.25 mm (0.325 inches). A tubular container as defined in Claim 1 wherein said release strip comprises a polymeric material. A tubular container as defined in Claim 7 wherein said release strip is a laminate comprising at least one layer of a polymeric material.

Inventors: HERRON GENE A, LOWMAN RICHARD M, LUBITZ ERIC P, MCCORKLE COSSIE J, SETTY THOMAS J, SUSKI WILLIAM C, HERRON, GENE A., LOWMAN, RICHARD M., LUBITZ, ERIC P., MCCORKLE, COSSIE J., SETTY, THOMAS J., SUSKI, WILLIAM C.
Applicants: SONOCO PRODUCTS CO, SONOCO PRODUCTS COMPANY
Application year: 1998
Main classification: B65D3
IPC codes: B65D3, B31B17, B65D17