WO1993013999A1

WO1993013999A1 - Peelable container seal

Info

Publication number: WO1993013999A1
Application number: PCT/US1993/000774
Authority: WO
Inventors: Floyd W. Blanchard
Original assignee: Blanchard Floyd W
Priority date: 1992-01-16
Filing date: 1993-01-15
Publication date: 1993-07-22
Also published as: AU3597493A

Abstract

A peelable container seal (31) includes a circular seal layer (35) and circular tab layer (36) joined at the outer edge thereof by a high strength weld. The seal layer (35) supports an adhesive coating utilized in attaching the seal layer to the edge of a container neck (51). In an alternate embodiment, the circular tab layer (36) is replaced by a pair of tab layers joined at a common fold line (38) near one side of the circular seal layer. A high strength weld is applied to the innermost tab layer (36) and seal layer (35) at a point diametrically opposite from the tab layer fold line.

Description

PEELABLE CONTAINER SEAL

SPECIFICATION

Cross Reference to Related Application

This application is a continuation-in-part of a copending application entitled REMOVABLE SEAL FOR LIQUID CONTAINER, filed October 16, 1990 in the name of the inventor of this application and having serial number 07/598,048 which is hereby incorporated herein by reference.

Field of the Invention

This invention relates generally to container sealing devices and particularly to those intended to be removed by a peeling action.

Background of the Invention

Most containers in use today include some type of sealing mechanism to protect the container contents and prevent leakage or spillage. A great number of the containers presently used include a container body having an upwardly extending generally cylindrical neck which defines a sealing edge and a plurality of threads for receiving a closed cap. Within the cap, a disk-like seal is usually provided which is bonded to the sealing edge of the neck container providing a tight tamper resistant seal. With the cap threaded unto the container neck, the seal is further strengthened and the contents of the container are protected. When the cap is removed, the seal remains bonded to the sealing edge of the container neck and must be removed to access the container contents.

Certain materials such as vehicle engine oil or other such additives are often dispensed from their respective containers by inverting the container and pouring the materials into a receiving aperture upon the vehicle. Many other liquid materials, however, are also dispensed in a similar inverted container pouring action.

In such container uses, the removal of the container seal effectively without spilling or misdirecting the container contents becomes a difficult task. To facilitate seal removal in such containers, practitioners in the art have attempted to use various types of pull tabs or similar devices usually directed toward the removal of the container seal while the container is inverted. For example, U.S. Patent 4,869,383 issued to Bahr, et al. sets forth a CONTAINER CLOSURE WITH PULL TAB in which a container includes an upwardly extending cylindrical neck having a plurality of threads for receiving a cap. A seal member is adhesively secured to the neck opening and includes an elongated pull tab which doubles back across the outer face of the seal and extends along the outer edge of the container neck beyond the cap. When the cap is removed and the container is inverted, the tab extends upwardly along the container neck and is used to peel the seal member from the neck while the container is inverted.

U.S. Patent 4,961,986 issued to Galda, et al. sets forth a SEALING MEMBER FOR A CONTAINER having a membrane such as aluminum foil and a first sheet formed of a material such as polyester, part of which is bonded to the membrane. The remaining portion of the polyester sheet is free of attachment to the foil and thus may be used to form a tab which facilitates seal removal.

U.S. Patent 4,863,061 issued to Moore sets forth a CLOSURE LINER WITH PULL TAB which includes a seal liner provided with a tab portion and adapted to seal the mouth of a container. A cap liner adapted to be adhered to the tab portion of the seal liner and releasibly retained within the cap is released from the cap upon cap removal and provides an enlarged gripping surface to enable the consumer to more easily open the container.

U.S. Patent 4,754,890 issued to Ullman, et al. sets forth a TAMPER EVIDENT SAFETY SEAL having a safety seal formed from a sealing liner which includes an integral tab portion. The tab portion is double-folded for increased strength.

U.S. Patent 4,739,892 issued to Tudek sets forth a CONTAINER CAP ASSEMBLY for use in combination with containers holding motor oil, antifreeze or other liquids to be poured into receptacles within an engine assembly. An air-tight seal is adhesively attached to the container opening which includes a string securely fixed to the top portion of the seal. The remaining end of the string is secured to the container cap to facilitate breaking the seal by pulling the string once the container is inverted.

U.S. Patent 4,782,967 issued to Thomas sets forth a MEDICINE VIAL OPENER for simultaneously rupturing and carrying away a breakable foil seal and packaging from a medicine vial or other container. The opener includes a string attached to the foil seal having one end thereof secured to the interior packing material and the remaining end exterior to the foil. The exterior end serves as a pull tab which when pulled ruptures the foil seal and then carries the seal away along with the interior packing material.

U.S. Patent 4,767,016 issued to Cook, Jr., et al. sets forth a LIQUID BOTTLE CAPPING ASSEMBLY having a perforated member fixedly attached to a bottle in a covering relationship with a threaded bottle opening together with a penetration discouraging device operatively associated with the perforated member to provide evidence of penetration of the perforated member such as by a hypodermic needle or the like. A sheet is fixedly attached to the penetration discouraging device and tearably removably attached to the perforated member for sealing the bottle opening and for providing evidence of tampering therewith.

U.S. Patent 4,605,136 issued to Debetencourt sets forth a SEAL WITH TEAR LIP FOR CONTAINERS receivable within the space between the container neck and container cover.

U.S. Patent 4,893,718 issued to Delespaul, et al. sets forth a CONTAINER WITH WELDED ON COVER AND SCREW CAP having a plastic seal member defining one or more outwardly extending tabs receivable upon a container neck and welded thereto in a sealing attachment.

U.S. Patent 4,789,082 issued to Sampson sets forth a CONTAINER DISCHARGE CONTROL for controllably retaining liquid in and releasing liquid from a squeeze deflectable hollow container having a tubular neck. A resilient seal is secured to the neck and is displaced from its sealing position by the force of the container contents as the container is squeezed.

U.S. Patent 4,819,819 issued to Robertson, Jr. sets forth a TAMPER EVIDENT CLOSURE for use with a container having a generally cylindrical upstanding neck or throat. The closure includes an annular element which slides into and mates with the throat of the container together with a cylindrical cup which frictionally engages the end of the annular element. A flat disk separable from the cup defines frangible lines in a spiral pattern to form a pull tab.

International application number PCT/US90/00335 in the name of McCarthy sets forth an IMPROVED INNER SEAL FOR CONTAINER AND METHOD OF APPLYING having a seal member adapted for fitting over an upper rim of a container and including a membrane for providing container seal. The seal member includes an extending grip tab to be used in removing the seal.

U.S. Patent 4,815,618 issued to Gach sets forth a TAMPER INDICATING DISPENSER CLOSURE having a closure adapted to be received upon a container neck which supports a hermetically sealed membrane to prevent contamination of the container contents. A disk secured to the membrane and pull ring serve to sever the membrane and open the sealed container.

U.S. Patent 4,778,698 issued to Ou-Yang sets forth an INNERSEAL FOR CONTAINER FOR USE WITH LIQUID CONTENTS having a facing bearing a layer of amorphous polyester on one major surface thereof. The inner seals forms a strong bond to a glass container and resists moisture more effectively than conventional innerseals.

While the foregoing prior art seal structures are effective in meeting many of the needs for sealed containers, there remains a continuing need in the art for evermore improved seal construction which provides a peelable container seal for effective use in pouring materials such as vehicle motor oil and the like into restricted access areas such as the orifices of vehicle motors.

Summary of the Invention

Accordingly, it is a general object of the present invention to provide a improved container seal. It is a more particular object of the present invention to provide an improved container seal which may be readily removed by the consumer using a convenient peeling action. It is a still more particular object of the present invention to provide an improved peelable container seal which is particularly advantageous for use in pouring liquids from inverted containers.

In accordance with the present invention, there is provided for use in combination with a container having a generally cylindrical neck extension and defining a neck passage and sealing edge, a peelable seal comprises: a generally circular tab layer formed of a plastic material and defining an outer edge; a generally circular seal layer formed of a plastic material and defining an outer edge, the seal layer being stacked upon the tab layer and defining an inner surface touching the tab layer and an outer surface; an adhesive coating formed upon at least a portion of the outer surface, the tab layer and the seal layer being joined proximate a portion of their outer edges.

Brief Description of the Drawings

The features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements and in which:

Figure 1 sets forth a perspective view of a multiple sheet fabrication of the present invention peelable container seal;

Figure 2 sets forth a perspective assembly view of the installation of the present invention peelable container seal within a container cap;

Figure 2A sets forth a section view of the peelable container seal of Figure 2 taken along section lines 2A- 2A therein;

Figure 3 sets forth a partial section view of a typical container neck supporting a peelable container seal constructed in accordance with the present invention;

Figures 4, 5 and 6 set forth sequential views showing the removal of the present invention peelable container seal of Figures 1 through 3 of a typical container neck; and

Figure 7 sets forth a perspective view of the fabrication of an alternate embodiment of the present invention peelable container seal;

Figure 8 sets forth a perspective view of a peelable container seal constructed in accordance with the alternate embodiment of Figure 4;

Figure 9 sets forth a perspective view of a peelable container seal constructed in accordance with the present invention secured to a typical container neck; Figures 10 and 11 set forth sequential views showing the removal of the present invention peelable container seal of Figures 7, 8 and 9 from a typical container neck.

Description of the Preferred Embodiments

Figure 1 sets forth a perspective view of a laminar sheet array constructed in accordance with the present invention and generally referenced by numeral 10. Sheet array 10 includes a planar tab sheet 11 preferably formed of a plastic material or the like together with a seal sheet 12. Seal sheet 12 is preferably formed of a laminated structure comprising a plastic lamination 13 and a foil lamination 14 joined in accordance with conventional fabrication techniques. Foil lamination 14 de ines an outer surface 15 which supports a layer of adhesive material having sufficient strength and bonding characteristics to provide a reliable seal and bonding attachment to the composite material typically used for plastic molded containers and the like. Tab sheet 11 and seal sheet 12 are supported in an overlapping pair and, in accordance with an important aspect of the present invention, a weld seam 20, which may form a continuous seam or intermittent "stitch-like" welds, is formed between seal sheet 12 and tab sheet 11 to provide a high strength attachment between the plastic material of tab sheet 11 and plastic lamination 13 of seal sheet 12. A plurality of circular cutting lines such as 21, 22 and 23 are formed in sheet array 10 in a partially offset relationship with respect to weld line 20 forming a corresponding plurality of peelable container seals such as seals 31, 32 and 33 respectively. In accordance with an important aspect of the present invention, the location of circular cuts upon sheet array 10 is chosen in a careful relationship to weld line 20 to provide a solid weld line attachment very close to the outer edges of the circular cuts which in turn provides the edge connection between the seal and tab portions of the present invention peelable seal. It should be noted that while a portion of sheet array 10 is shown in Figure 1, for purposes of illustration in a practical manufacturing environment, the pattern shown in Figure 1 may be repeated in a two-directional plane a multiple number of times to provide a great number of peelable seal structures from a single sheet array using a high speed mass production process. It should also be noted that in accordance with an important aspect of the present invention, circular cuts such as cuts 21, 22 and 23 are performed simultaneously upon seal sheet 12 and tab sheet 11 in a single cutting or punching operation.

Figure 2 sets forth a perspective view of a peelable seal formed in accordance with Figure 1 prior to assembly within a typical container cap generally referenced by numeral 40. Thus, in accordance with conventional fabrication techniques, cap 40 includes a molded plastic housing 41 defining a cylindrical neck recess 42 having supported therein a plurality of threads 43. Cap 40 further defines an end surface 44 completing the closure end of cap 40. In accordance with the present invention, a peelable seal 31 comprises a circular tab 36 and a circular seal layer 35 having common diameters and being commonly joined along a weld seam 38 near the edges of tab 36 and seal layer 35. With temporary reference to Figure 1, it should be recalled that weld 38 is formed by the formation of weld line 20 between sheets 11 and 12 in sheet array 10. It should also be noted that in the position shown in Figure 2, seal 31 formed by circular cut 21 in Figure 1 is inverted prior to assembly within cap 40 such that tab 36 is beneath seal layer 35 and thus adhesive layer 37 formed upon seal layer 35 is properly positioned to provide adhesive attachment to the container neck when cap 40 is assembled to its corresponding container in the manner shown in Figure 3. Thus, returning to Figure 2 with peelable seal 31 positioned as shown in Figure 2, the assembly thereof within cap 40 is carried forward by simply inserting seal 31 into recess 42. In its preferred form, seal 31 is sized slightly larger than the interior diameter of threads producing a somewhat "snap-fit" during the insertion of seal 31 which acts to maintain seal 31 within container 40. The combined assembly of cap 40 and seal 31 is at this point ready for use in the filling operation to be mated with the neck portion of a standard container.

Figure 3 sets forth a perspective view of a typical container neck upon which the present invention peelable seal has been assembled in accordance with conventional filling and sealing operations. Specifically, a typical container generally referenced by numeral 50 defines a cylindrical neck 51 supporting a plurality of external threads 52 and defining an edge 53. In the position shown in Figure 3, peelable seal 31 has formed a secure attachment to edge 53 of neck 51 in accordance with conventional bonding and adhesive operations utilizing adhesive coating 37. While the attachment between seal layer 35 and edge 53 of neck 51 may be provided using a variety of presently available bonding operations, it is believed advantageous to utilize an adhesive material for adhesive layer 37 which facilitates the use of high speed attachment processes such as hot melt adhesive or the like. Thus, in the position shown in Figure 3, the assembled combination of cap 40 and peelable seal 31 formed in Figure 2 has been threaded upon neck 51 and the above-described hot melt adhesive process or similar operation has been carried forward to provide an adhesive attachment between seal layer 35 and edge 53 of neck 51. Thereafter, cap 40 may be removed leaving peelable seal 31 secured to neck 51 in the manner shown in Figure 3.

It is important to note at this point that once cap 40 is removed, the attachment provided by adhesive 37 between seal layer 35 and edge 53 of neck 51 continues to maintain the sealed closure of neck 51. It should also be noted that tab 36 is free of attachment to seal layer 35 with the exception of weld 38 and thus tab 36 may be pivoted or flexed away from seal layer 35 in the direction indicated by arrow 54.

With temporary reference to Figure 2A taken along section lines 2A-2A in Figure 2, it should be noted that seal layer 35 and tab 36 are joined along weld 38 in a high strength attachment. Specifically, seal layer 35 is formed of a plastic lamination 34 and a foil lamination 30. Correspondingly, tab 36 is formed of a plastic material similar to or at least compatible with plastic 34. Thus, when weld 38 is formed between plastic lamination 34 of seal layer 35 and tab 36, the plastic layers are fused along weld 38 giving rise to a high strength attachment at the outer edge of peelable seal 31 having strength equal to or exceeding that provided by the prior art "folded over tabs". As is set forth below in greater detail, this high strength attachment near the outer edge of peelable seal 31 permits the application of substantial peeling force as tab 36 is pulled which breaks the adhesive attachment between seal layer 35 and the container edge at the ideal point during the liquid pouring process.

Returning to Figure 3, with cap 40 having been removed as described above and with peelable seal 31 maintained in sealing attachment to edge 53 of neck 51, the integrity of container 50 is maintained despite the removal of cap 40. In accordance with the present invention, peelable seal 31 may be removed from neck 51 by moving tab 36 in a pivoting or flexing motion in the direction indicated by arrow 54 to a sufficient separation to facilitate the user's grasp of tab 36 on both surfaces thereof. During this pivoting or flexing action, weld 38 continues to maintain the attachment between tab 36 and seal layer 35. It should also be noted that in accordance with an important aspect of the present invention, the full circular diameter of tab 36 provides ample gripping surface areas for the user to effectively grasp tab 36. In addition, the placement of weld 38 at the outer edge of seal 31 exposes virtually the entire undersurface of tab 36 to the user's fingers further enabling a secure grip upon tab 36. Once the user has obtained a secure grip upon tab 36, the user then pulls in the direction indicated by arrow 55. The user's pulling force is communicated by tab 36 to seal layer 35 solely in the region of weld 38 which produces a stress between edge 53 and adhesive 37 beneath weld 38 forming a separation point 39. As the force continues to be applied to tab 36 in the direction of arrow 35, the strength of adhesive 37 is overcome and seal layer 35 begins separating from edge 53 in the manner set forth below in Figure 5. It is important to note that the use of weld 38 at the outer edge of seal 31 causes separation point 39 to occur initially at one point on the periphery of neck 51. Thus, the peeling action as tab 36 is pulled and seal layer 35 separates from edge 53 begins at a single separation point 39. Thus, despite being formed from individual circular laminations, peelable seal 31 provides the peeling action of a folded over tab of the type known in the prior art while maintaining the advantages found in forming seal 31 using two full circular laminations rather than folded tab structures.

Figures 4, 5 and 6 set forth the sequential pouring operation of a typical liquid container in an inverted pour environment such as that generally encountered in motor vehicle engine additives and lubricating oils within the motor vehicle engine compartment. It will be apparent, however, that the present invention peelable seal is equally applicable to virtually any container seal environment.

With specific reference to Figure 4, container 50 is shown inverted such that cylindrical neck 51 extends downwardly and supports threads 52. In the position shown in Figure 4, cap 40 has been removed in the manner described above leaving peelable seal 31 secured to edge 53 of neck 51 by adhesive layer 37. Thus, seal layer 35 remains securely bonded to edge 53 about its entire periphery at the point shown in Figure 4 and, as a result, the contents of container 50 (not shown) remain captivated within container 50 despite container 50 being inverted. As described above, peelable seal 31 further includes circular tab 36 joined to seal layer 35 at weld 38. Thus, the position shown in Figure 4 corresponds generally to the initial positioning of container 50 prior to the removal of peelable seal 31 to permit the contents of container 50 to be poured downwardly as desired. Accordingly, and in accordance with an important aspect of the present invention, container 50 is shown positioned close to and above a receptacle 63 which includes a pouring aperture intended to receive the contents of container 50. In further accordance with an important aspect of the present invention, the high strength attachment between tab 36 and seal layer 35 being positioned at the edge of seal 31 permits the user to obtain ample gripping surface area upon tab 36 using fingers 60 and 61 and thus facilitates the peeling action. Thus, in the position shown in Figure 4, the user has gripped tab 36 between fingers 60 and 61 in preparation for peeling seal 31 away from edge 53 of neck 51.

Figure 5 sets forth the initial peeling operation in which the user has pulled tab 36 in the direction indicated by arrow 64 with sufficient force to overcome the adhesive attachment between seal layer 35 and edge 53 producing separation therebetween which begins at separation point 39. Thus, in accordance with an important aspect of the present invention, it should be noted that the separation between peelable seal 31 and edge 53 of container neck 51 begins at a single separation point 39 which is clear of fingers 60 and 61. As tab 36 continues to be pulled in the direction of arrow 64, the separation therebetween increases from the initial separation point. As a result, the material contained within container 50 begins pouring downwardly into receptacle 63 at a single point between neck 51 and seal layer 35 and does not spill onto the user's fingers. Thus, an easily controlled pouring situation results and undue spilling or other problems are minimized.

Figure 6 sets forth the peeling operation of the present invention seal near the completion of the removal of seal 31 from container neck 51. As can be seen, the user's fingers 60 and 61 are completely clear of the pouring stream between container 50 and receptacle 63. Thus, the user's fingers are removed from the pouring stream and are not subject to contact with the liquid within container 50.

Figures 7 through 11 set forth an alternate embodiment of the present invention functioning substantially in accordance with the embodiment shown in Figures 1 through 6 with the primary difference being the replacement of tab 36 with a two layer folded tab formed by tab layers 73 and 74. This alternate configuration provides additional gripping surface area and tab length to further improve the peeling operation by which the peelable tab of the present invention may be removed from the container neck. Specifically, with reference to Figure 7, seal sheet 12 is again shown formed by a plastic lamination 13 and a foil lamination 14. As is also set forth above, foil lamination 14 supports an adhesive material coating 16. A folded tab sheet 71 comprising plastic tab layers 73 and 74 folded along a fold edge 72 is positioned overlying seal sheet 12 such that fold edge 72 is close to the outer edge of seal sheet 12. In accordance with the present invention, a high strength weld is applied between tab layer 73 and plastic lamination 13 of seal sheet 12 along a weld line 82. It should be noted that tab layer 74 is not subjected to the high strength weld. A plurality of circular cuts such as circular cut 80 are then formed in sheet array 70 producing corresponding peelable seals such as seal 81.

Figure 8 sets forth a perspective view of peelable seal 81 showing seal layer 35 joined to folded tab layers 73 and 74. Also shown is the high strength weld attachment at weld 82 between tab layer 74 and seal layer 35. Once again, but for the use of a folded tab layer pair, peelable seal 81 is virtually identical to peelable seal 31 set forth above. It should be noted that, in accordance with an important advantage of the embodiment shown in Figures 7 through 11, the use of folded tab layers 73 and 74 with a singular attachment at weld 82 produces an extended gripping surface for the tab portion of peelable seal 81.

Figure 9 sets forth a perspective view of peelable seal 81 secured to neck 51 of container 50 in the manner described above for peelable seal 31. As can be seen in Figure 9, tab layers 73 and 74 may be separated along fold 83 to produce the extended length pulling tab described above. Once again, seal layer 35 is secured to edge 53 of neck 51 by adhesive 37. The attachment of tab layer 74 to seal layer 35 at weld 82 once again configures the present invention seal to provide a single initial point of separation between seal layer 35 and edge 53 referred to as separation point 39.

Figure 10 sets forth the initial pouring step in which container 50 is shown inverted having neck 51 bearing threads 52 extending generally vertically. In the position shown in Figure 10, peelable seal 81 remains secured to edge 53 of neck 51 due to the adhesive attachment between seal layer 35 and edge 53. In preparation for the peeling of seal 81, tab layer 73 has been unfolded from tab layer 74 in the manner described in Figure 9 and the user has grasped tab layer 73 using fingers 60 and 61. In preparation for the peeling of seal 81, container 50 is lowered to close proximity to receptacle 63. Thereafter, the user applies an outward force in the direction indicated by arrow 91 upon tab 73. This pulling force is coupled to weld 82 by tab layers 73 and 74 producing a separation force between seal layer 35 and edge 93 at separation point 39. Once the adhesive strength of the adhesive bonding of between seal layer 35 and edge 53 is overcome, seal layer 35 separates from edge 53 in the manner described above in Figure 5 at separation point 39 to produce a single point of separation and an easily controlled pouring action.

Figure 11 sets forth the completion stage of the pouring operation for container 50 in which peelable seal 81 is near complete removal. Once again, it should be noted that the embodiment shown in Figures 7 through 11 of the present invention provides the above-described advantages due to the edge placement of weld 82 which produces the advantages of a folded over tab structure while maintaining the continuous periphery of seal layer 35. While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects. Therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Claims

THAT WHICH IS CLAIMED IS:

1. For use in combination with a container having a generally cylindrical neck extension and defining a neck passage and sealing edge, a peelable seal comprising:

a generally circular tab layer formed of a plastic material and defining an outer edge;

a generally circular seal layer formed of a plastic material and defining an outer edge, said seal layer being stacked upon said tab layer and defining an inner surface touching said tab layer and an outer surface;

an adhesive coating formed upon at least a portion of said outer surface,

said tab layer and said seal layer being joined proximate a portion of their outer edges.

2. A peelable seal as set forth in Claim 1 wherein said tab layer and said seal layer are joined by a high strength weld.

3. A peelable seal as set forth in Claim 1 wherein said seal layer further includes a foil layer interposed between said outer surface and said adhesive coating.

4. A peelable seal as set forth in Claim 3 wherein said tab layer includes a pair of layers mutually joined at a fold junction and wherein said seal layer is joined to one of said pair of layers at a point diametrically opposed to said fold.

5. For use in combination with a container having a generally cylindrical neck extension and defining a neck passage and a sealing edge, a peelable seal comprising:

a generally circular seal membrane adhesively secured to said neck at said sealing edge;

a generally circular tab having a perimeter generally coextensive with said seal membrane; and

attachment means joining said seal membrane to said tab proximate the outer edges thereof,

said tab when pulled in a direction generally away from the area in which said tab and said seal membrane are joined causing a separation between said neck edge and said seal membrane to begin at a single separation point.

6. A peelable seal as set forth in Claim 5 wherein said seal membrane and said tab each include plastic layers and in which said attachment means include a weld junction formed therebetween.

7. A peelable seal as set forth in Claim 6 wherein said tab further includes a pair of tab layers mutually overlying and joined at a fold, said fold being positioned oppositely from said weld junction.

8. A peelable seal as set forth in Claim 5 wherein said attachment means include a junction between said seal membrane and said tab which is at least as strong as said seal membrane or said tab.

9. A peelable seal as set forth in Claim 7 wherein said fold and said weld form chords across said circular seal which are generally parallel and of substantially equal length with respect to the circular perimeter of said seal membrane.