US3480173A - Composite closure - Google Patents

Description

Nov. 25, 1969 J. .M. WHEATON 3,480,173

COMPOSITE CLOSURE Filed Nov. 20, 1967 I VENTOR. l 4 JAcK .WHATDU 10 United States Patent 3,480,173 COMPOSITE CLOSURE Jack M. Wheaten, Toledo, Ohio, assignor to Owens- Illinois, Inc., a corporation of Ohio Filed Nov. 20, 1967, Ser. No. 684,318 Int. Cl. B65d 41/60 US. Cl. 21556 6 Claims ABSTRACT OF THE DISCLOSURE A tamper-proof closure including an outer tear-off cap and an inner resilient cap element which, in conjunction with the outer cap, functions as a sealing gasket and, upon removal of the outer cap, has utility as a re-closable snapcap.

Background of the invention This invention relates to closures for receptacles; more particularly, it relates to composite closures for containers for processed or hot-packed foods in which an outer tearoff element is provided with an inner separable liner member having utility as both a sealing gasket and a snap-cap.

As a general proposition, closures, and especially closures for receptacles containing processed or hot-packed foods, should possess certain attributes if they are to be widely accepted in the packaging industry. In this regard, there are at least five such attributes which are highly preferential. First, if the ultimate consumer is to accept the closure, it must be capable of removal with relative ease. Second, the ability to hermetically seal a receptacle is essential to the maintenance of a high-quality product. Third, and somewhat related to the ability to hermetically seal is the desirability that the closure configuration provide a barrier which virtually precludes the possibility of insects infesting the internal surfaces of the closure and thereby the contained product. Fourth, the closure should also possess re-seal or reclosing features whereby, after an initial quantity of the packaged contents has been consumed, the remaining portions may be protected from dust, dirt, and the like. Fifth, a tamper-proof feature is desirable as it ensures the consumer that the product is retained in its original high-quality state as packed.

Though somewhat limited, the packaging industry has in general found success in utilization of the so-called tear-off closure. However, when evaluated by the general standards hereinbefore noted, it is not at all surprising that this type closure has achieved less than its full potential due to its most notably lacking a re-seal or re-closing feature. Attempts to eliminate this inherent deficiency by providing an inner liner element capable of functioning as a separable re-seal snap-cap have, at least within the food packaging industry, been unsuccessful. These attempts to utilize an inner liner as a re-seal snap-cap after removal of the outer retaining shell have apparently been unsuccessful because of what might be described as a sagging, or downward distortion, of the panel portion of the liner during processing of the sealed receptacle.

In the case of hot-packed foods, the processing most commonly employed involves a technique generally de signated in the art as steam displacement. Here the product is first pre-heated and dispensed into the receptacle at a temperature slightly below the boiling point of water, the temperature of the product at filling generally being in the range of 170-200 F. Following this filling a surge of steam is used to displace the air existing in the headspace and a closure is then applied substantially contemporaneously with the steam displacement to seal the receptacle. Subsequent cooling of the contained product and receptacle causes the steam, or water vapor, to condense, thereby producing a vacuumized headspace. In the fore- 3,480,173 Patented Nov. 25, 1969 going process, as well as in the alternate processing technique of retorting, the closure or sealing elements are first subjected to somewhat elevated temperatures and then to a cooling cycle to form a vacuum. The deterimental sagging of the liner seems to result from having two dissimilar pressure zones existing between the packaged contents and the outer retaining shell, the first zone being that defined by the inner surface of the liner panel and the upper surface of the product, i.e. the headspace containing steam or water vapor, and the second being an air zone. existing between the inner surface of the outer sealing closure and the outer surface of the inner liner. As the liner generally comprises a resilient thermoplastic material, it is softened by being subjected to the elevated temperatures and this causes a slight initial sagging. Because of the dissimilar thermodynamic properties of air and water vapor, as the sealed receptacle and product are cooled, the water vapor in the first zone begins to condense and form a vacuum while the air in the second zone is incapable of so doing; thus, a substantial differential pressure is created between the two zones. The resultant pressure thereby creates a downwardly directed force on the upper surface of the liner panel causing a permanent sag or deformation which severely limits the capability of the liner to function as a readily-removable snap-cap.

Summary of the invention With the foregoing in mind, there is provided in accordance with this invention a composite tamper-proof closure for hermetically sealing a receptacle, wherein the closure is easily removable from the receptacle to which it is aflixed, it possesses reclosing features as desired or required, and the problem of insect infestation is virtually eliminated.

More particularly, there is provided in accordance with this invention a closure combination comprising a resilient, snap-cap liner functioning as a sealing gasket and an outer metallic retaining cap serving as a seal and retaining shell, the liner being readily separable and usable as a reclosable snap-cap if desired after removal of the metallic shell. A feature of the snap-cap liner which is of major import, especially when employing the closure combination with receptacles containing processed or hot packed foods, is the provision of a venting feature which substantially eliminates detrimental downward sagging or deformation of the liner panel portion during the processilng steps in which vacuum is formed within the receptac e.

The specific nature. of this invention, as well as other advantageous features thereof, will become apparent to those skilled in the art by reference to the drawings which, by way of example, illustrate an embodiment of this invention.

Brief description of the drawings In the drawings:

FIGURE 1 is a fragmentary vertical sectional view showing an outer protective cap positioned over the liner member prior to sealing.

FIGURE 2 is a perspective view of the sealed receptacle, portions thereof being cut away for purposes of illustration.

FIGURE 3 is a fragmentary vertical sectional view similar to FIG. 1 of a receptacle having the re-closable liner of this invention sealed thereon.

Description of preferred embodiments eral rib or protuberance 18 having its outer surface 20 disposed externally of the adjacent neck portion. As will be seen shortly, this protuberance provides the receptacle with a feature for retaining the closure thereon and functions as a sealing surface to hermetically seal the contents within receptacle 10.

The closure for receptacle comprises an outer shell or cap 22 and an inner, separable resilient snap-cap liner 24, the latter serving as a sealing gasket when utilized in conjunction with outer cap 24 and as a re-closable snap-cap when utilized independently. While the outer cap may be of any suitable material such as tin-plate or aluminum, the latter is preferred because of its greater facility for providing tear-off features as contemplated in this invention. Similarly, the liner may be comprised of a well-known thermoplastic material, the most common of which are polyamides, polyesters and polymers or copolymers of compounds having olefinic unsaturation such as, for example, ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate and acrylonitrile. However, as this invention contemplates the use of the composite closure with comestibles, the preferred materials are those which are impermeable to oxygen, vinyl polymers being the most suitable.

Inner liner 24 includes a panel portion 26 and an integral surrounding annular skirt portion 28, the liner being adapted to be engagingly positioned about receptacle mouth .16 with skirt portion 28 extending downwardly over protuberance 18. Additionally, the liner includes a feature for easily releasing it from the receptacle. In the preferred embodiment, this feature is provided by an outwardly projecting annular ledge 30 formed integral with the lower margin of skirt 28, the liner thereby being released by exerting a slight upward force on the ledge. It will, of course, be readily apparent that any suitable means for accomplishing this removal may be provided, for example a tab formed along skirt 28. As priorly noted, for purposes of substantially eliminating downward distortion of the liner during vacuumization of the receptacle it is of great importance that the panel 26 be punctured or provided with pressure-relief opening. Preferably, this puncture takes the shape of a slit 32.

Similarly outer cap 22, which is positioned about liner 24, essentially comprises a panel 34 and an integral downwardly depending annular skirt 36 which extends downwardly of protuberance 18 and laterally of liner skirt 28 (FIG. 1). The cap in its preferred embodiment is of the tear-oft" type and thereby possesses easy removal features. Any of the numerous configurations well known in the art for providing a cap with tear-off characteristics may be utilized. Exemplary of these is the ring tab having lines of weakness, or score lines, emanating therefrom and generally illustrated in the drawings as 33 and 35 respectively. Cap 22 is affixed to the receptacle by exerting an inwardly-directed force upon the cap skirt 36 which causes an inward distortion of the skirt as shown in FIGURE 2. This inward distortion causes liner skirt 28 to become compressed between the outer sealing surface 20 of protuberance 18 and the internal surface of skirt 36, thereby utilizing the liner as a gasket for hermetically sealing the receptacle. Additionally, this inward skirt distortion effectively locks the cap about the receptacle as the lower margin of skirt 36 is permanently disposed inwardly and downwardly of protuberance 1-8.

In passing, it should be mentioned that this inward distortion of cap skirt 36 provides the sealed package with features which are advantageous during a retorting operation. With conventional lug caps, for example, those skilled in the art readily appreciate the fact that, since the cap is attached to the container by a relatively small number of lugs, blow-off during retorting is a distinct possibility. Unlike lug cap however, this invention contemplates a circumferential attachment of the outer cap to the container. Consequently, because of the continuous nature of the attachment, the sealed container is capable of sustaining a greater internal pressure during retorting and, thereby, allows the retorting to proceed with less back-pressure than heretofore required to preclude cap blow-offs.

From the foregoing, it should be readily apparent that once applied, the closure precludes the entrance of air into the receptacle because of the compressive interaction of cap skirt 36 and sealing surface 20 with liner skirt 28. Furthermore, with the background of this invention in mind, because of the slit in liner panel 26 it is, unlike prior art devices, virtually impossible for two dissimilar vapor zones to co-exist as the slit maintains a vapor passageway between the outer cap and the receptacle headspace.

Thus, when the sealed receptacle is cooled in the normal processing step to produce a vacuumized headspace, the venting feature provided by the slit maintains a single equilibrium vapor pressure in the receptacle. Thus, such opening eliminates the differential pressures existing in prior art closure-liner combinations and thereby substantially eliminates objectionable sagging or deformation. Additionally, the slit ensures an easy release of the liner after the outer cap has been removed. That is, when the outer cap is removed by lifting the ring tab 33 and pulling the tab along score lines 35, the slit allows air to enter the receptacle headspace and thereby dissipates the priorly existent vacuum. This in turn allows the liner to be released by exerting a slight upward force on the ledge 30 which is not counteracted by vacuum. Because of the substantial elimination of the liner sagging and the ease with which the liner is released, it is left undistorted and thereby retains its original snap-cap features. Hence, the liner can be re-applied to the receptacle as desired to protect any unused contents from contamination due to dust, dirt and the like.

While a specific embodiment of this invention has been described in detail above, it will be apparent to those skilled in the art that modifications are possible. Accordingly, the foregoing is to be considered exemplary, not limiting and the true scope of this invention is to be measured by the following claims.

I claim:

1. In a package for processed or hot-packed comestibles comprised of: a receptacle having a neck defining a mouth opening thereof and including a sealing surface on said neck; a liner positioned about said mouth opening having a central panel and including a peripheral skirt compressingly engaging said sealing surface and means integral with said skirt for releasing said liner from said receptacle; an outer protective cap having a complemental central panel and integral depending skirt positioned about said liner, said skirt engaging said liner skirt to hermetically seal said receptacle and tear-off means on said cap; the improvement wherein said liner central panel is provided with an access opening to maintain a single equilibrium vapor pressure within the receptacle and outer cap to, thereby, substantially prevent sagging and deformation of the liner due to a vacuum sealing operation.

2. An improved package comprising in combination with a glass container having a neck defining the mouth opening thereof and including a peripheral protuberance on said neck, a resilient snap-cap liner having a panel and including an integral perimetric skirt, said liner being engagingly positioned about said mouth opening with said perimetric skirt extending downwardly of said peripheral protuberance, said panel having a slit-type opening for maintaining a single equilibrium pressure in said container and said skirt including integral means formed at its lower margin for releasing said liner from said container, an outer protective cap positioned about said liner having a panel and an integral downwardly-depending skirt compressingly engaging said liner skirt, whereby said liner sealingly engages said peripheral protuberance to hermetically seal said container, and tear-off means on said cap for removing said ca from said container, the liner being readily separable from said cap thereafter having utility as a snap-cap for reclosing said receptacle.

3. The package of claim 2 wherein said liner is composed of a polymer or copolymer of compounds having olefinic unsaturation.

4. The package of claim 2 wherein said liner is composed of polymers or copolymers of compounds selected from the group consisting of ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, and acrylonitrile.

5. In a package for fluent product comprised of a receptacle having a neck defining a mouth opening thereof and including a sealing surface on said neck; a resilient snap-cap liner for snap-on engagement With said neck about its mouth opening and having a central panel and peripheral annular skirt, said liner peripherally engaging said sealing surface, and means on said skirt for snap-off release of said liner from said neck, an outer protective cap having a complemental central panel and depending skirt positioned to substantially overlie said liner, said skirt engaging said liner skirt to tightly seal said receptacle and a tear-off means on said outer cap for removal of the latter, said liner central panel being provided with an access o ening to vent differential vapor pressure Within the receptacle and beneath said snap-cap liner.

6. An improved package comprising in combination with a glass container having a neck defining the mouth opening thereof and including a peripheral protuberance on said neck, a resilient snap-cap liner having a panel and including an integral annular skirt, said liner being snapped over said mouth opening and its said skirt releasably engaging said peripheral protuberance, said panel having a vent opening for equalizing internal vapor pressure of said closed container, an outer protective cap positioned about said liner having a panel and an integral downwardly-depending skirt tightly engaging said liner skirt, whereby said liner sealingly engages said container, and tear-off means on said cap for removing said cap from said container, whereupon said liner vent opening connects the interior of the container to atmosphere.

References Cited UNITED STATES PATENTS 3,223,279 12/1965 Wheaton 22060 3,276,613 10/1966 Bozek 21546 3,325,033 6/1967 Wheaton 215--39 GEORGE T. HALL, Primary Examiner US. Cl. X.R.

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