Re-usable Seal For Tab Opening Cans

Abstract

A re-usable seal for cans of the pull-tab type. The seal consists of a unitary structure of an abrasion-resistant elastomer. The structure has a dependent skirt portion forming a small angle such as 10.degree. with a line perpendicular to the edge of the can to facilitate insertion of the seal. Within the skirt portion and a flat base portion is disposed a system of reinforcing ribs which preferably intersect each other at right angles for reinforcing the structure while permitting it to be deformed into the aperture of the can. A flat tab may extend from the seal structure to facilitate removal of the seal.

Description

BACKGROUND OF THE INVENTION

This invention relates generally to seals, and particularly relates to a deformable, re-usable seal for sealing the pull-tab opening of a can.

Cans having a pull-type tab are enjoying increasing popularity. They are used for beer, soft drinks as well as fruit and vegetable juices. However, once the can has been opened by pulling its tab and removing the attached portion of the top, the carbon dioxide of the beer or soft drink rapidly goes out of the drink, thus making the drink go flat. In the case of fruit or vegetable juices the flavor is rapidly lost unless the can is resealed to preserve the flavor or the "fizz." The seal also serves to protect the contents free from contamination.

Accordingly, many suggestions have been made in the past for a seal for a can having a pull-type tab. Some of these devices are complex in structure and hence expensive. Thus, two-piece stoppers have been suggested which are impractical and have a metallic insert. Other seals rely on a groove that must be inserted into the edge of the can aperture by folding the seal. Such seals cannot really be made tight to seal in the delicate flavor of the contents. Furthermore, such seals are solid and hence not yieldable along the edge of the can aperture.

Other seals rely on beads that must be molded about the edge of the can, an expensive and impractical procedure in the average home. Some seals are created to close the triangular hole created in a can top by a can opener, and are not adapted for the generally keyhole-shaped preformed opening of a pull-type tab. Other sealing devices are designed to form part of the pull tab of the can and must be made by the can manufacturer. Furthermore, some of the prior art seals are not adapted to be re-used and hence must be discarded after each use. Finally some of the resealing plugs which are known are rather complicated in structure and not of a unitary material. If such a seal does not seal within the opening of the can but rather above the opening, a reliable seal cannot be guaranteed.

Although there has been a veritable plethora of approaches to the problem of effectively re-sealing a soft drink can, as indicated by the various types of seals of the prior art described hereinabove, none of them have found widespread acceptance in the marketplace, either because of their complexity, cost, crudeness or ineffectiveness. Yet there is a clear need for an effective sealing device for soft drink cans of the pull-top type. Soft drink bottle seals are widely marketed and used, even though they are only partially or intermittently effective at best. As a result, bottled soft drinks are purchased by preference to canned soft drinks for certain purposes, such as the home bar and other uses where only a portion of the can or bottle is needed at a time, even though canned soft drinks are markedly cheaper and more convenient. The development of an effective re-sealing device for pull-top cans, such as is provided by the present invention, would undoubtedly increase the market for canned soft drinks.

It is accordingly an object of the present invention to provide a seal for the opening in a can created by a pull-type tab which is simple in construction and may be inexpensively manufactured.

Another object of the invention is to provide a seal of the type referred to which is re-usable.

A further object of the invention is to provide a reusable seal for the purposes referred to herein which is capable of yielding when inserted into the opening of the can yet is sufficiently rigid and permits deformation of the seal to provide a secure sealing action.

SUMMARY OF THE INVENTION

A re-usable seal in accordance with the invention serves the purpose of sealing the aperture in a can created by removal of a pull-type tab secured to a portion of the top defined by scoring the lid. The seal consists of a unitary structure of an elastomer having abrasion-resistant properties. This structure has a body portion of an outline generally conforming to the keyhole-like aperture in the can to be re-sealed. A dependent skirt portion extends from the body or base portion and forms an acute angle such, for example, as 10.degree. with a line perpendicular to the edge of the can forming the aperture. This facilitates insertion of the seal into the aperture in the can and improves the integrity of the sealing effect after insertion.

A system of reinforcing ribs is disposed in the skirt portion to reinforce the seal yet to permit deforming it into the aperture. Preferably the ribs comprise two sets of mutually intersecting ribs extending at approximately 90.degree. to each other. Finally a tab may extend from the body portion to facilitate removal of the seal from the can.

The novel features that are considered characteristic of this invention are set forth with particularity in the appended claims.

The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description when read in connection with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a can with an opening created by a pull-type tab and sealed by the seal of the invention;

FIG. 2 is an enlarged sectional view taken on line 2--2 of FIG. 1 and showing a section through the seal of FIG. 1 without the can;

FIG. 3 is an enlarged sectional view taken on line 3--3 of FIG. 1 and showing another section through the seal without the can;

FIG. 4 is an enlarged sectional view, similar to that of FIG. 2 but showing the seal inserted into a can;

FIG. 5 is a side-elevational view of the seal of the invention after molding but before its gate portion has been removed;

FIG. 6 is a side-elevational view of a modification of the seal of the invention with a thick tab adapted to extend at an angle from the can top;

FIG. 7 is a top plan view of a modified seal in accordance with the invention.

FIG. 8 is an enlarged sectional view taken on line 8--8 of FIG. 7 and illustrating the seal skirt in relation to the body surface; and

FIG. 9 is a sectional view of another modified seal in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, and particularly to FIGS. 1 to 3 there is illustrated a can 10 having a top 11 connected to the side walls by a rim or bead 12. The generally keyhole-shaped opening 14 created by the pull-type tab is sealed by the seal 20 of the invention. This seal 20 consists of an elastomeric material such, for example, as a copolymer of styrene and butadiene. Such a copolymer is sold in the trade under the trademark "KRATON" by Shell Chemical Co., a division of Shell Oil Co., Synthetic Rubber Division. However, the seal 20 may also consist of other elastomers such as polyurethane or the group known as vinyls. Polyolefins are also appropriate for use for this purpose, as are certain natural and synthetic rubbers. It is important, however, that the material employed be impervious to the contents so as not to affect the flavor thereof. In any case the elastomer preferably has abrasion-resistant properties. Other desirable properties of the seal will be referred to hereinafter.

The seal 20 consists of a substantially flat base surface or body portion 21, and a skirt portion 22 interconnecting the base surface 21 to a rim 23. The skirt 22 forms a generally conical structure, that is, it forms an angle A with a line 24 which is disposed vertically to the rim 23 or to the top 11 of the can. This angle is preferably on the order of 10.degree. but may be within the range of approximately 5.degree. to approximately 25.degree..

Finally disposed in the space formed by the base surface 21 and the skirt 22 there is a system of reinforcing ribs 25 and 26 forming ribs which intersect at right angles. Preferably the ribs 25, 26 extend throughout the height of the skirt 22 as shown in FIGS. 2 and 3. In addition, one of the ribs, that is, rib 27 may have a particular configuration to engage a matching shape of an ejector pin to facilitate ejection from the mold during fabrication. In any case the ribs 25 to 27 have the purpose to stiffen the seal, yet to permit yielding of the structure to facilitate a sealing relationship between the edge 14 of the seal and the skirt 22.

As shown by the dotted lines 30 in FIG. 3 the ribs 25 need not extend all the way to the edge of the rim 23. They may extend only to the bottom portion of the rim 23. The reason is that the seal then only enters the can until the lower surface of the rim 23 rests on the can top 11, and hence not all the ribs need extend to the top of the rim. Also a rib such as 27 may be entirely omitted to increase flexibility of the seal, when desired.

Finally, the seal may be provided with a tab 32. As shown in FIG. 2 the tab 32 may extend along the plane formed by the rim 23 and may have the same thickness as the rim.

The seal 20 is inserted into the aperture 14 of the can top 11 as shown in FIG. 4. Since the seal consists of an elastomer, it is deformable and yields when inserted. An outwardly extending bulge 33 is formed below the can top 11 while the skirt 22 is deformed inwardly as shown at 34. Due to the thus formed bulges and deformations 33 and 34 which develop as lateral forces in the skirt 22 against the can lid, a perfect seal may be obtained to retain the flavor and fizz of the drink.

Since the edge 14 of the can may be sharp and the can may consist of various metals such, for example, as steel or aluminum, an abrasion-resistant material for the seal is important. Other properties of the elastomer which are desirable for the seal of the invention are listed below. The table below gives a range of properties with those of "Kraton" also being shown.

Property From To "Kraton" __________________________________________________________________________ Tensile Strength in pounds per square inch 650 1950 1500 Elongation in percent 500 1150 800 Hardness, Shore A 58 92 72 Abrasion Resistance in cubic centimeters per kHz. Taber (ASTM D1044-56) 0.15 0.28 0.22 Yerzley Resilience (ASTM D945-59) Resilience, at 20% deflection, in percent 65 85 75 __________________________________________________________________________

It should be noted that Shore A is a standard hardness test for elastomers. ASTM stands for the American Society for Testing Materials, and the number of the test relied upon has also been noted.

The seal of the invention may be molded by a standard injection molding method. Conventionally a cold die or mold cavity is used and the hot elastomer is injected directly. The elastomer is then set up or cooled and finally ejected. To this end the hot elastomer is injected through the gate or entrance direct to the cavities. This has a suitably narrowed portion to facilitate breaking away when the finished article is ejected from the mold. This has been shown in FIG. 5 where the seal 20 with its base surface 21, skirt 22 and rim 23 is shown with a gate portion 36 which breaks off at 37 when the mold is opened prior to ejection of the seal from the mold cavity.

FIG. 6 to which reference is now made illustrates another seal having a base surface or body portion 21, a skirt 22 and a rim 23. Here, as in FIG. 5, the tab 40 is thicker than the rim 23 so that the tab 40 extends upwardly at an angle from the can top 11 as shown when the seal is inserted into the aperture 14. This construction of the tab will facilitate gripping the tab by hand to remove the seal.

Another modification of the seal is illustrated in FIGS. 7 and 8. Here the base surface or body portion 41 forms the top rather than the bottom of the seal. The skirt 42 extends downwardly from the sealing surface 41 and is open along the bottom. The rim 43 forms an extension of the (top) base surface 41 as does the tab 45. Two sets of ribs 46 and 47 intersect each other at right angles. As shown in FIG. 8 the ribs 46, 47 need not extend over the entire height of the skirt 42. They need only extend downwardly far enough to stiffen the seal where it is in contact with the rim of the can. Hence the lower portion of the skirt 42 may be made quite flexible to facilitate insertion of the seal into the can opening.

Thus the modification of the seal shown in FIGS. 7 and 8 has the advantage that the lower skirt portion is very flexible. Hence even if there are slight differences in the shape of the aperture 14 and of the outline of the skirt 42, the seal can still be used due to its greater flexibility. Moreover the upper flat surface 41 is well-suited to imprinting of advertising, as to identify the source of the canned goods with which the seal is to be used. On the other hand its disadvantage is that the ribs 46 and 47 extend into the liquid of the can. Since dirt deposits may collect in the space formed by the interior of the surface 41, the skirt 42 and the ribs 46, 47, this construction requires careful cleaning of the seal before it is used again. Otherwise the liquid contained in the can may be contaminated.

FIG. 9 shows still another modification of the seal of the invention. The section of FIG. 9 generally resembles that of FIG. 3. However, two tabs 50 are shown extending substantially at right angles to the sealing surface 21. This construction, of course, insures that the tabs are unobstructed and can be readily grasped for removal of the seal. Moreover removal is facilitated because gripping the tabs 50 between thumb and forefinger pinches them together, thus developing a lateral force tending to pull the skirts 22 away from the can edges as the seal is lifted out. In all of the examples herein the ribs 25 and 26 are tapered toward the top, that is, in a direction away from the base surface 21.

It should be noted that all the seals illustrated in the drawings are of unitary construction. Preferably they are all made of an elastomer with the properties listed above and may consist of a suitable polymer or copolymer as listed above.

There has thus been disclosed a re-usable seal for any can having a pull-type tab. The seal is of unitary construction and may be molded of a relatively inexpensive material that is chemically inert, abrasion-resistant, flexible and resilient. The properties of the material are enhanced by the construction employed which renders the seal flexible and resilient. Due to a system of internal supporting ribs the seal is made sufficiently stiff, yet is capable of yielding. It is deformable when inserted into the aperture of a can to be sealed, hence creating a positive, tight seal that will retain the flavor and hold the carbon dioxide pressure of any carbonated drink contained in the can. The seal has a generally conical shape which permits its ready insertion into the can.

Although there have been described above specific arrangements of a re-usable seal for the tab opening cans in accordance with the invention for the purpose of illustrating the manner in which the invention may be used to advantage, it will be appreciated that the invention is not limited thereto. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art should be considered to be within the scope of the invention.

Claims

What is claimed is:

1. A re-usable seal for sealing the aperture in a can created by a pull-type tab, said seal comprising:

a unitary structure consisting of an elastomeric material having abrasion-resistant properties, said structure having a body portion of an outline generally conforming to that of the aperture in the can;

a dependent skirt portion extending from said body portion and forming an acute angle with a line perpendicular to the edge of the can forming the aperture to facilitate insertion of said structure into the aperture;

a system of reinforcing ribs disposed within said skirt portion to reinforce said structure but to permit deforming it into the aperture for sealing relationship therewith; and

a tab portion extending from said body portion to facilitate removal of said structure from the can.

2. A seal as defined in claim 1 wherein said angle formed between said skirt portion and said line is between approximately 5.degree. and approximately 25.degree..

3. A seal as defined in claim 1 wherein said angle formed between said skirt portion and said line is approximately 10.degree..

4. A seal as defined in claim 1 wherein said reinforcing ribs consist of two sets of intersecting ribs extending substantially at right angles to each other.

5. A seal as defined in claim 4 wherein said reinforcing ribs extend through substantially the entire height of said dependent skirt portion.

6. A molded seal as defined in claim 5 wherein at least one of said ribs has a cross-sectional configuration shaped to engage an ejector pin for effecting ejection during the molding process.

7. A seal as defined in claim 1 wherein said structure is molded of a copolymer of styrene and butadiene.

8. A seal as defined in claim 1 further including an edge portion extending laterally outward from the body portion and in line with said tab portion.

9. A seal as defined in claim 8 wherein said tab and edge portions extend substantially parallel to the edge of the can upon insertion of the seal.

10. A seal as defined in claim 9 wherein said tab portion is substantially thicker than the edge portion and deformable to an upwardly angled direction when the seal is inserted in pull-top can aperture.

11. A re-usable seal for sealing the aperture in a can created by a pull-type tab, said seal comprising:

a unitary structure consisting of an abrasion-resistant elastomeric material, said structure having a body portion of generally U-shaped cross section and having an outer sealing rim portion;

said body portion including a dependent skirt portion forming an angle of approximately 10.degree. with a line perpendicular to the edge portion of the can forming the aperture, said skirt portion having an outline generally conforming to that of the aperture in the can;

said body portion including a substantially planar base portion;

two sets of intersecting reinforcing ribs extending substantially at right angles to each other, said ribs extending from said base portion substantially through the space enclosed by said skirt portion; and

a tab extending from said rim portion for facilitating removal of said structure, said structure being adapted to be inserted into the aperture with said base portion extending into the can, whereby only said base portion is exposed to the liquid in the can.

12. A seal as defined in claim 11 wherein said ribs and skirt portion are resiliently deformable to permit insertion and retention of the seal against internal pressure within an aperture formed in a pull-top can.

13. A seal as defined in claim 11 wherein said tab is thicker than said rim portion so that said tab extends upwardly from the can after the seal has been inserted.

14. A seal as defined in claim 11 wherein said structure is molded of a copolymer of styrene and butadiene.

15. A seal as defined in claim 11 wherein said structure consists of an elastomer having a tensile strength between approximately 650 and approximately 1,950 pounds per square inch, an elongation between approximately 500 percent and approximately 1,150 percent, a hardness between approximately 58 and approximately 92 (Shore A), a Taber abrasion resistance between approximately 0.15 and approximately 0.28 cubic centimeters per kHz., and a Yerzley resilience at 20 percent deflection between approximately 65 percent and approximately 85 percent.

16. A seal as defined in claim 11 wherein said tab extends substantially parallel to said rim portion.

17. A seal as defined in claim 11 wherein said base portion extends in a plane substantially coincident with the plane formed by said rim portion.

18. A seal as defined in claim 11 wherein said base portion extends across the edge of said skirt portion opposite said rim portion.

19. A seal as defined in claim 11 having a pair of tabs extending vertically from opposite rims of the seal and arranged for developing lateral inward forces upon pinching of said tabs together.

20. A seal as defined in claim 11 having a configuration during molding including a narrowed gate portion formed to be sheared off during the opening of the mold.