US3748816A

US3748816A - Method of sealing a container

Info

Publication number: US3748816A
Application number: US00109560A
Authority: US
Inventors: R Asmus
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-10-02
Filing date: 1971-01-25
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31

Abstract

A reclosable container having a removable top closure mechanically joined to the container body to carry the structural loads of container and contents, the mechanical joint being cylindrical and connected and disconnected by rotation of the top closure and the container body relative to each other. The ultimate seal during the shelf-life between filling and initial opening of the container is effected by a rupturable band adhered over the joint, said band in the locus of the joint line having a strength in shear less than its adhesive bond to the container closure and body adjacent the joint line. The closure and body are preferably recessed adjacent the joint line to receive the band. The band is preferably endless and formed in situ by application of band material in liquid condition; a repellent or adhesion inhibiter (preferably an immiscible liquid) may be located in or over the joint line to exclude entrance of the band material into the joint and provide an equatorial area of weakness for rupture of the sealing band.

Description

United States Patent 1 Asmus [45] July 31, 1973 METHOD OF SEALING A CONTAINER [76] Inventor: Richard W. Asmus, 3628 W. 48th St., Cleveland, Ohio 44102 221 Filed: Jan. 25, 1971 211 Appl. No.: 109,560

Related US. Application Data [62] Division of Ser. No. 863,105, Oct. 2, 1969, Pat. No.

3,303,761 2/1967 Monroe etal. .93/44.1R

Primary Examiner-Robert L. Spruill AttorneyEly, Golrick & Flynn [5 7] ABSTRACT A reclosable container having a removable top closure mechanically joined to the container body to carry the structural loads of container and contents, the mechanical joint being cylindrical and connected and disconnected by rotation of the top closure and the container body relative to each other. The ultimate seal during the shelf-life between filling and initial opening of the container is effected by a rupturable band adhered over the joint, said band in the locus of the joint line having a strength in shear less than its adhesive bond to the container closure and body adjacent the joint line. The closure and body are preferably recessed adjacent the joint line to receive the band. The band is preferably endless and formed in situ by application of band material in liquid condition; a repellent or adhesion inhibiter (preferably an immiscible liquid) may be located in or over the joint line to exclude entrance of the band material into the joint and provide an equatorial area of weakness for rupture of the sealing band.

6 Claims, 3 Drawing Figures -l i wk 30 il 1 22 L 3/ PATENIED JUL 31 ms METHOD OF SEALING A CONTAINER This application is a divisional application with re spect to my copending application Ser. No. 863,105, filed Oct. 2, 1969, now US. Pat. No. 3,608,772.

This invention relates to an improvement in containers and a method of making them. More particularly this invention relates to containers having a removable top closure which is, on the'one hand, readily opened manually without the aid of opening tools or equipment, and, on the other, provides a mechanically strong and thoroughly sealed closure whereby solid and liquid material may be packaged and maintained at suitable pressures (either sub-atmospheric or superatmospheric if not simply atmospheric pressures) during the expected shelf-life of the packaged contents between the filling of the container and its initial opening by the user.

Both as an element of commercially produced closures for cans, jars, or like containers, or as a temporary means employed by users for securing the covers or lids on such containers, it has long been a common practice to employ an external adhesively secured band wrapped around the substantially cylindrical wall formed at the joint or line of juncture between the closure member and the body of the container. Thus, in a can closure, for example, in which there is simply a frictional slip joint between the cylindrical wall of the container body and a depending flange of a top closure, it has been commercial practice to over-wrap the joint with a removable band of an adhesive tape orthe like, both to secure the closure member from accidental removal and improve its seal. Likewise, it is a common expedient for housewives, for example, to secure the screw top of a can or jar, after opening and reclosing, with a strip of pressure-sensitive tape which is removed to allow ready re-opening of the container. In the quest for readily-opened containers, particularly those by which liquid and/or solid materials can be packaged under super-atmospheric pressures or vacuum or those in which the processing of the contents after filling and closing may develop substantial internal pressure, the foregoing expedients of using an external band to effect sealing have not been successful, despite their convenience.

It is an object and advantage of this invention to provide a sealed, reclosable closure for cans, jars, and the like which may be readily opened, the sealing being effected by an externally applied sealing band. It is an advantage of this invention that, during the expected shelf-life of the packaged contents, and irrespective of whether the contents are packaged at atmospheric pressures, super-atmospheric pressure, or under partial vacuum, the packaged contents will be thoroughly sealed but, nonetheless, may be manually opened without requiring the aid of opening tools or accessories. Further, such opening and rupturing of the seal may be accomplished substantially instinctively by the user and without the need for unusual operations or instructions therefor which may be overlooked or not followed by the users.

Other objects and advantages of this invention will be apparent from the following specification, claims, and drawings, of a preferred embodiment which may be substantially modified in whole or part:

may removably close and reclose the can, the can being effectively'sealed after filling and until it is initially opened by the user.

FIG. 2 is an elevation of the preferred embodiment disclosed in FIG. 1. 8

FIG. 3 is a cross-section of an alternate form of sealing band which, when applied to a container as illustrated in FIG. 1, may have the external appearance shown in FIG. 2.

It is to be understood that in the accompanying drawings the thicknesses and proportions of the several elements shown have been exaggerated for clarity of illustration, and, for the smame purposes, structural details, such as the beading of raw edges of sheet-metal used for cans or lids, for example, have been eliminated.

In essence this invention depends upon separating the functions of the conventional gasketed screw or bayonnet locked top or lids for cans, bottles, jars, and the like of both providing the structural strength of the closure to resist mechanical loads on the closure and also sealing the joint between the closure and the container body by compressing a gasketing member located in the joint. Particularly if the contents are packaged so as to maintain a pressure differential from that of the ambient atmosphere or if, after the contents have been packaged, the package must be subjected to protional load between the mating thread or lug portions FIG. 1 is an essentially diagrammatic representation in cross-scction of the upper portion of a metal can having a bayonnet-type ofjoint for a closure top which of the connection that it becomes extremely difficult to loosen the connection for opening without the aid of an opening device or resorting to such expedients as tapping the closure to dislodge the connection or heating the closure so as to expand it without expanding the mating portion of the connection. By reducing the function of the gasketing member, if one is employed, to that of simply filling gross gaps or discontinuities in the joint between the container closure and body and relying upon an external sealing band covering the joint, adequate structural strength to resist any normal mechanical load on the container may be obtained without frictional resistance to easy opening.

The problems heretofore inherent in transferring such sealing functions to an external sealing band have been solved in this invention by the discovery that various suitable banding materials, inert to the packaged contents and the ambient atmosphere, may have more than adequate strength to seal any leakage from the contents through the mechanical joint of the closure and the container (or leakage into such contents) and yet are so relatively weak in shear strength that they will rupture in shear rather than break an adjacent adhesive bond to structurally stronger materials, such as the sheet metal, glass, or plastic conventionally used for containers and container closures.

To illustrate the application of this discovery to the invention, reference is made to FIGS. 1 and 2, as follows.

As shown in FIG. 1, a tubular can body 10, for example, is formed of suitably plated and lacquered sheet metal and provided with a closable opening or mouth portion 11 of reduced diameter. This mouth portion 11 is formed with one or more, usually two or three, internal grooves 12 (one is illustrated in dotted lines in FIG. 1) extending downwardly from the rim of the mouth and then curving to a gently pitched helical location below the rim to provide internal bayonet joint slots or interrupted threads. The can body is closed with a drawn metal lid having a downwardly depending flange 21 forming a gripping portion substantially equal in diameter to that of the can body. The flange is reduced in diameter below the gripping portion to provide a gasket seat shoulder 22 and below the shoulder 22, the flange 21 is further reduced in diameter to a sleeve portion 23 which internally fits the can body mouth 11. The sleeve portion 23 is formed with internal dimples 24 which form raised bosses which are received in the grooves 12. Externally the sleeve portion 23 carries a gasket ring 25 which is lightly compressed between the shoulder 22 and rim of the mouth portion 12 when the lid 20, with the bosses of the dimples 24 received in the grooves 12, is turned clockwise to draw the lid into the mouth portion 11 of the can body 10.

Manifestly, the depending flange of the closure lid 20 may fit externally of the mouth portion 11 of the can body 10, in which event the gasket 25 will usually be located interiorly of the flange so as to be engaged between an internal shoulder of the closure lid and the rim of the mouth portion of the can body and a second or alternate gasket may be located in the external circumferential joint between the rim of the sleeve portion of the closure flange 21 and the shoulder between the can body and its mouth portion 11. The arrangement shown in section in FIG. 1 is generally preferred, however, since it enables a relatively shallow circumferential channel 26 to be formed between the lower edge of the gripping portion of the flange 21 and the shoulder between the can body and its mouth portion 11, locating the external joint line between the can body and its closure in the center of the channel 26. If the sleeve portion 23 of the closure fits externally of the mouth portion 11 of the can body, it is preferable to provide a stepped shoulder between the can body and its mouth portion, the upper step of such shoulder receiving either rim of the sleeve portion 23 or a gasket engaged by that rim and the lower step providing the lower side of a channel in which the external joint line is centrally located. The radial depth of the channel 26 is preferably such as to contain the outwardly extending ridges of the grooves 12 below the cylindrical surface defined by the gripping surface of the closure flange 21 and the wall of the can body 10; this allows a cover tape 35, described below, to be flush with that surface. Such a channel depth also usually allows any portion of the gasket 25 which may be bulged when the closure 20 is tightened and drawn into the can by operation of the bayonet lock effected by the grooves 12 and dimples 24 to be contained within the channel.

Manifestly, instead of the bayonet lock illustrated as the mechanical connection between the can body 10 and closure 20,'the location of the dimple 24 on the sleeve portion 23 and the groove 12 on the mouth portion 11 may be reversed or a coarse screw connection of one or more continuous or interrupted threads may be employed. Likewise, while the container body 10 and closure 20 are indicated as being of formed sheet metal in FIG. 1, manifestly the same container structure and closure structure may be molded of plastic, glass, ceramics, and/or other suitable material and the material of the container body need not be the same as that of the closure.

As indicated above, the gasket 25 is preferably only lightly compressed as the container is closed by turning the closure 20 down on the container body 10; the function of the gasket 25, which may be of natural or synthetic rubber or other elastomer, polyethylene, an acrylic thermoplastic (e.g., Barex 210), molded cork, compressible paper or film, and the like, is primarily to fill any gross gap in the joint between the con tainer closure and body and to take up any play in the mechanical connection between these two principal members of the container and secondarily to provide a necessary mass to inhibit gas diffusion. With any sealing function of the gasket 25 thereby being otherwise incidental, the mechanical connection between the closure and body can thereby be designed to be amply strong to withstand mechanical loads which the container may be expected to encounter while holding the frictional engagement between the locking elements to minimal loads that can be pre-set within close tolerances.

The actual sealing of the contents of a container as described above is effected by a sealing band 30, after the closure has been connected as described above. The band 30 is preferably of a polymeric film material which is relatively adherent to the material of the can body 10 and closure 20 or which can be made adherent thereto with appropriate adhesion promoter. It is preferably applied by a roller coater, fountain brush, narrow knife coater, or masked spray while it is in liquid form so as to cure or be cured in the channel 26 at a sufficient depth to cover the gasket 25 and thereby form itself in situ to an endless band. Suitably plasticized vinyl plastisols, plasticized hot-melt resins, and high solids content solvent dispersions or latices of polymeric film-forming resins, such as epoxy-phenolic, epoxy-urea, and polybutadiene resins, are examples of the general class of materials which may be deposited in liquid form over the joint line between the container closure and body to provide the desired adherent sealing band.

When the adherent sealing band is formed in the channel 26 as defined above, it is desirable to provide a non-adherent or less adherent equatorial area in the locus of the joint line which will permit ready rupture of the band in shear; this may be accomplished by one of the following means: The materials of the gasket 25 and the band 30 are either selected to be mutually repellent and immiscible so that there is no significant adhesion between the gasket 25 and band 30 or, prior to application of the band, the exposed surface of the gasket is coated with a narrow strip of liquid which blocks adhesion of the band to the gasket and which also preferably seeps into any interface between the gasket and the edges of the joint line; if no gasket is provided in the external joint line, the joint is filled with such an adhe sion blocking liquid prior to application of the band 30. The composition of the adhesion blocking liquid will necessarily vary according to the composition of the band material and the relative repulsion or immiscibility of them. For example, if the band 30 is formed of a relatively hydrophobic vinyl plastisol, a relatively hydrophilic glycerol or sugar syrup may be employed to block adhesion in the locus of the joint. Alternatively, the sealant band-forming liquid may be fonnulated so as to be sufficiently viscous or thixotropic .that it will not seep into the joint.

As an alternative to the formation of the sealing band 30 in situ, one may employ heat-sealing tapes, such as a plasticized vinyl tape which may be fused to itself and the container elements, provided, of course, that an adhesion block is located in or at the joint line of the container. If preformed films or tapes are used, care must be taken to assure not only that a secure, leak-free vertical seam between the butted or overlapped ends of the tape is obtained but also that the tape is well adhered on either side of the joint line while leaving an intermediate unadhered portion of sufficient width over the joint line to allow shearing forces to develop and rupture the tape as the closure and container body are twisted relatively to each other to open the container.

Due to the reduction in thickness of the band 30 over the gasket 25, due either to the bulging of the gasket or the effect of the adhesion blocking liquid, or both, there is thereby provided an internal score line 31 for rupture of the sealing band 30 when the band is subjected to shear by turning the closure 21 counterclockwise to open the container. The thickness of the sealing band at the locus of the joint may thereby be closely controlled and effectively pre-set to limit the torque required to open a sealed container. Ifthe band 30 is formed from a length of pre-formed tape or film, either an external or internal score line may be cut into the tape to control the torque necessary to rupture the tape and insure that the force necessary to do so will be less than the adhesive bond to the container body and closure.

The sealing band 30 may be pigmented, if desired, to provide an attractive ornamentation of the container. However, its surface may be relatively soft and subject to scuffing during shipment and handling. To so protect the band 30, and provide a printable display surface and, in some cases, for sanitary reasons, a protective band 35 may be employed. The band 35 may be an encircling band of shrinkable cellulose, vinyl, or other shrinkable film, or it may be a strip of paper, tough plastic, metal foil, or a laminate of one or more of these materials; it may be adhered to the sealing band 30 by a pressure-sensitive or like peelable adhesive or may be simply frictionally secured by a tight seam of adhesive 36 between overlapped ends, as shown in FIG. 2. In any case, the band 35 is preferably provided with a free lifttab 37 to permit it to be stripped readily. The band 35 may also serve an actual scaling function, particularly when made of metal foil or a metal foil laminate, by increasing the impermeability of the sealing band 30 as well as by serving as a reinforcement for the polymeric resin of the band 30. For example, if the contents of the container are packaged under a substantial vacuum or under relatively high super-atmospheric pressures imposed by gaseous contents, such a pressure differential could eventually rupture the band 30 at one or more points along the line 31 unless the sealing band were reinforced by the peelable or shrunk-fit band 35.

While it is preferred to form the sealing band 30 from a polymeric resin in a liquid condition and which may be cured in place over the joint line between the container body and closure,as described above, this invention is not limited to use of such sealing band. Particu= larly when a prime requisite for the sealing band is its function as a barrier against transmission of moisture and like vapors and gases, it may be desirable to form a band 130 of a metal foil or laminated foil and/or paper or film. As shown in FIG. 3, the band may be formed of a strip having

marginal portions

132 and 133 folded back on and preferably laminated to its center portion 131 and either the marginal portions or the corresponding areas of the center portion 131 are then adhered to the can body and closure so that the line or space 134 between adjacent edges of the marginal portion overlies the joint line between the closure and body and is preferably free of adhesive in the locus of that line. The ends of such a folded band of strip material may be joined by a lapped vertical seam corresponding to the seam 36 shown in FIG. 2 and the external end may have a lift tab corresponding to the lift tabs 37 to rupture the vertical overlapped seam joining the ends of the band. When adjacent adjacnet edges of the

marginal portions

132 and 133 are spaced to provide a gap 134 as shown in FIG. 3 and the marginal portions are adhered to the can body and closure, such a gap is usually sufficient to receive the bulging of a gasket in the joint and may be made wide enough to insure that any adhesive forced toward the joint line as the marginal portions are pressed against the container and closure wall will flow into the gap 134 rather than into the joint between the container body and its closure and still leave an unadhered portion overlying the joint line. When the material of the band 130 consists of aluminum foil having gauge of 0.0001 to 0.0006 inch, it is usually desirable to protect such relatively soft foil from abrasion by an overlying removable protective band 35.

As in the case of a sealing band 30, a sealing band 131 can have adequate structural strength to perform its function of sealing the mechanical joint between the container body and its closure. Yet, upon the manual application of torque (within limits which can be predetermined to close tolerances), the closure and container body can be readily rotated with respect to each other so as to rupture the band in shear over the joint line. A relatively clear line of fracture appears to be aided by slight tension placed on the circumferential line of weakness in the sealing band, which tension is most conveniently obtained with a mechanical interlock between the closure and container body which causes the closure to move helically away from the container body as they are rotated with respect to each other.

If this container body 10 is, as shown in the drawings, that of a sheet metal can having a conventional crimped and sealed bottom closure, the usual practice is to assemble and complete the closing and sealing of the top closure according to the invention, inverting the container to fill it with the contents introduced through the open bottom, and then closing and sealing the container with the conventional bottom closure. if the container body 10 is that of a conventional jar or bottle which can be filled only through an open mouth, this invention permits such filling with most contents which can be packaged in such container. If, as in the case of many foodstuffs, the contents to be packaged require processing at high temperature after filling and sealing in order to sterilize or pasturize them, an advantage of this invention is that such processing temperature can also cure or complete the cure of the sealing band so as to adhere it firmly to areas adjacent the joint line of the closure.

While a sealing band rupturable in shear according to the invention is preferably received in a circumferential channel in which the joint line between the container body and closure is located, it is to be understood that such surface configuration adjacent the line may be omitted so that the band will protrude from the surfaces adjacent the joint line. The rupturable sealing band is usually cylindrical, or substantially so, since the joint line between the container body and its closure is usually a circle lying in the perimeter of an area provided by adjacent marginal portions of the container body and closure, which area is essential cylindrical. if the area defined by marginal portions adjacent the joint line is other than essentially cylindrical, then, so long as it is essentially the surface of a solid of revolution, a sealing band 130 can usually be shaped to lie over the joint line while being adhered securely to the adjacent area of the container and closure; an advantage of forming the band 30 in situ is, of course, that it can accommodate itself to extremely irregular surfaces adjacent the joint line.

Still other modifications and departures from the disclosed specific embodiment of this invention can be made without departing from the scope of the following claims. In the following claims, it is to be understood that the term unadhered as applied to the medial portion of the sealing band overlying the joint line as an equatorial area between the adherent marginal portions includes the modification of causing or allowing such circumferential area to be more weakly adhered than, and thus relatively unadhered with respect to, the more strongly adhered marginal portions. in this connection, so far as it is understood, a function of such unadhered (or less strongly adhered) circumferential medial area of the sealing band appears to be that of allowing shearing strains, adequate to rupture the band, to develop upon rotation of one marginal portion of the band with respect to the other. It has also been observed that, within the limits of a sealing band of a material and thickness in its circumferential medial area capable of being ruptured in that area due to torque applied to the marginal portion which remains adhered, if resistance to rupture in the medial circumferential area of the sealing band exceeds that which is convenient for manual application of such torque, such resistance may usually be decreased by increasing the axial width of the circumferential area; similarly, if such resistance to rupture is less than that desired, it may be increased by decreasing the width of the medial unadhered portion.

What is claimed is:

l. A method of sealing a container comprised of a body having a mouth portion with a substantially circular edge and closed by a closure interfitting said mouth portion to provide a circular outer joint line comprising the steps of locating a sealing band over said joint line and circumferential areas of said closure and said mouth portion adjacent said joint line and adhering said band to said marginal circumferential areas with adhesive bonds stronger than the shear strength of said band while avoiding such adhesion of a medial portion of said band at said joint line.

2. A method as defined in claim 1 including the step of filling said joint line with a repellant to adhesion to said sealing band prior to locating said sealing band over said joint line.

3. A method as defined in claim 2 including the step of forming said sealing band in situ by applying a polymeric resinous liquid coating over said joint and adjacent marginal circumferential areas and curing said coating to a solid condition to adhere the same to said circumferential areas but without adhesion at said joint line.

4. A method as defined in claim 3 including the step of reinforcing said sealing band with an overlying band of flexible but relatively inelastic sheet material, of the class consisting of metal foil, organic film, paper, and laminates thereof.

5. A method as defined in claim 1 in which said sealing band is comprised of a strip of flexible sheet material of the class consisting of metal foil, organic film, paper, and laminates thereof and including the step of joining the ends of said strip with a transverse overlapped seam to form and locate said band.

6. A method as defined in claim 5 including thestep of first folding marginal portions of said strip toward the longitudinal center thereof and joining the same to the unfolded portion of said strip to provide a strip having marginal portions of greater shear strength than the medial portion thereof.

Claims

1. A method of sealing a container comprised of a body having a mouth portion with a substantially circular edge and closed by a closure interfitting said mouth portion to provide a circular outer joint line comprising the steps of locating a sealing band over said joint line and circumferential areas of said closure and said mouth portion adjacent said joint line and adhering said band to said marginal circumferential areas with adhesive bonds stronger than the shear strength of said band while avoiding such adhesion of a medial portion of said band at said joint line.

4. A method as defined in claim 3 including the step of reinforcing said sealing band with an overlying band of flexible but relatively inelastic sheet material of the class consisting of metal foil, organic film, paper, and laminates thereof.

6. A method as defined in claim 5 including the step of first folding marginal portions of said strip toward the longitudinal center thereof and joining the same to the unfolded portion of said strip to provide a strip having marginal portions of greater shear strength than the medial portion thereof.