Container And Closure Therefor And Method Of Manufacture Thereof

Abstract

A closure is provided having a low-torque removal requirement implemented by obstructions within the annular upper extremity of a cap which receives a disk-like gasket seated within said obstructions adapted to be transferred to contiguous sealing relation to the closure mouth; the cap and container assembly method integrates the disk sealing operation with disk seal transfer. A flexible flange seat receives the disk which projects therebeyond for flexibility of its free end, thereby permitting annular obstructions on the cap to ride more freely thereover as the disk is unseated from within the cap.

Description

BACKGROUND OF THE INVENTION

This invention relates to a container closure assembled into a low-torque seal which permits ready removal of the closure cap while employing the cap to temporarily seat disk-like sealing means and facilitate its transfer to a closure mouth.

The assembly of high integrity seals onto easy openable containers presents problems which are at cross-purposes in their solution. On the one hand, the container closure should be of an integrity that minimizes leakage through the closure. On the other hand, providing such sealing means on the closure limits the ease with which the closure can be unscrewed or otherwise removed from the container; frictional engagement of the gasketing or sealing means needed to provide seal-tight integrity offsets the ease with which the closure can be unscrewed from the closure opening.

It is among the objectives of the present invention to provide a simple expedient whereby these requisites can be ameliorated and thus meet the objectives of seal-tight integrity and ease of removal of the container's closure capping means.

SUMMARY OF THE INVENTION

In accordance with the invention, a plastic cap is provided with an annular bead or series of lugs in its cylindrical upper extremity in its inner side wall so as to receive a disk-shaped sealing gasket which fits complementarily within the annular undercut portion and obstruct axial displacement thereof; these annular obstructions serve as means to resist removal of the gasket from the cap while providing sufficient geometric clearance to permit the free end of the gasket to ride over the lugs as the cap is unscrewed from a closure mouth after the gasket is sealed thereon. The gasket is loosely and temporarily seated within the cap which is thereafter screwed as by threads located within the cap on an outer annular wall of the closure mouth; the mouth is preferably defined by a flexible flange or lip which serves to seat the underface of the gasket and be in abutting face-to-face relation therewith as a result of the cap and gasket in combination being screwed onto the closure mouth; in this connection, the flange will be preferably formed to flare slightly upwardly at a very slight acute angle to a place perpendicular to the axis of the container's mouth and thus be pre-stressed as the flange is depressed to a horizontal plane relative to the longitudinal container axis to assure abuttment with the sealing gasket. Thereafter the disk is activated by heat to cause an adhesive laminated to the underface thereof to seal the disk to an annular seat on the flange of the closure mouth whereby said closure opening and gasketing disk are integrally seated in seal-tight relation and the seal is effectively transferred from its temporary seat within the cap to the permanent closure position required for sealing integrity. The disk thickness is less than the axial dimension of the space between the underside of the cap and the annular means for obstructing disk removal, the disk perimeter area having sufficient flexibility to permit the cap to be unscrewed and snapped free of the lugs. The cap's annular obstructions are designed so that the disk free ends can be overridden thereby as the cap is unscrewed from the closure mouth; in this connection it is preferable to have the sealing disk project a substantial distance beyond the perimeter of the closure mouth and that the mouth itself be relatively flexible to permit such overriding of the obstructions relative to the disk-shaped sealing gasket as will be described hereinafter.

Referring now to the accompanying drawings depicting the invention;

FIG. 1 is a side view of the complete closure mouth and assembled with cap sealing gasket and closure opening with part shown in vertical section and part in elevation;

FIG. 2 is a top plan view of the closure shown in FIG. 1 with part broken away to better show closure mouth, the gasketing means intermediate the mouth and the cap;

FIG. 3 is an enlarged sectional view taken along line 3--3 in FIG. 2.

FIG. 4 is a plain view of the sealing gasket in place with the cap removed; and

FIG. 5 is a still further enlarged sectional view of the flange seat for the sealing gasket taken along line 5--5 in FIG. 4.

Referring now to the drawings, the closure mouth will be seen to comprise an annular cylindrical wall portion 10 connected by an upwardly and inwardly flaring supporting wall 12 integral with a substantially flat inwardly directed flange portion 14, the closure mouth thus defined being formed on a suitable container of low-density polyethylene or like flexible thermoplastic polyolefin polymer that is soft and deformable; the preferred form of container is a flexible bellows shaped container 16. Preferably the closure mouth and container will be blow-molded into an integral flexible unit having an external thread 18 formed on wall 10.

The flange 14 will preferably be formed so as to have a smooth upper surface and will slope slightly upwardly at a minor acute angle of, say, less than 3.degree. whereby the flange which seats the gasket to be hereinafter described will be deflected downwardly as a cap is screwed onto the closure as will be described hereinafter.

A cap generally shown as 20 is likewise formed of like plastic deformable material as that of the container and comprises a flat disk portion 22 having a cylindrical skirt 24 with internal threads 26 formed therein and adapted to thread onto closure mouth threads 18. The closure cap 20 may have a dispensing orifice 28 communicating with a nozzle 30 adapted to issue container contents therethrough after the cap is removed and the sealing means to now be described are removed and the cap is re-applied to the closure mouth. The underface of the flat disk portion 22 is smooth and is adapted to receive the sealing means for rotatable low friction engagement therewith.

A flat disk-shaped gasket 32 having aluminum foil ply 33 coated with a ply of heat activatable thermoplastic resin 34 on the underside thereof is adapted to snap temporarily into a seat formed in cap 20. This seat is preferably defined by an annular interrupted bead formed in the upper extremity of the innerface of cap skirt 24 which thus serves to obstruct removal of the gasket from the cap. The interrupted beads thus form lugs generally shown as 38 which are so proportioned in their overall arc length as to provide a pre-determined resistence to removal of the sealing disk from the cap as the lugs are caused to move upwardly over the free edge or outer rim of the disk-shaped gasket. In this connection, the upper face of the obstructing annulus or lugs are preferably formed so as to have a frustro-conical surface that flares downwardly and inwardly from the interior of the cap skirt as shown at 38a which overrides the free edge of gasket 32 and moves upwardly thereover when unscrewing the cap after the gasket has been sealed to flange mouth 14.

It will be noted that the cap is adapted to temporarily seat gasket 32 therewithin and that the cap and gasket are screwed on the closure mouth 10 prior to activation of the sealing ply 34. By threading the cap downwardly, the closure mouth flange 10 is brought into face-to-face planar relation with the gasket 32 which function is fostered by the flexibility of the material forming the closure mouth. In addition, the frustro-conical wall portion 12 provides further flexibility to the flange 14 to permit the cap 20 to be screwed down relatively tightly and bring the abutting faces of the gasket and the flange into maximal preactivation contact.

After cap 20 has been threaded on the closure mouth 10 the sealant will be activated by heat applied through a suitable induction heating element which contacts the cap and transmits heat to the sealing ply 34 through the heating of foil ply 33. By virtue of the thermoplastic character of flange 14 and the sealing ply 34, the abutting surfaces thereof melt or merge with one another to effect a relatively strong seal sufficient to require the gasket 32 to be peeled from the closure mouth. Preferably, the free edge of the sealing gasket projects outwardly beyond the perimeter of cylindrical wall portion 10 sufficiently to possess a certain degree of flexibility relative to the balance of the gasket. In this way, the surface 38a of the interrupted annular beads or lugs can ride more freely upwardly and overcome the resistence to flexure by the gasket when the cap is unscrewed preparatory to unsealing the gasket for removing the container contents.

To assemble and seal the container with the afore-described closure members, the base of wall 10 has an annular recess 40 which is gripped by suitable assembly means (not shown) whose function it is to hold the flexible bellows container to a fixed vertical axial position in the assembly line. The cap 20 in an inverted position has gasket 32 snapped therein with the laminating heat-activatable sealing ply 34 exposed. The cap with the gasket is then returned to the upright uninverted position and screwed onto annular wall 10 until gasket 32 abuts and is in frictional contact with flange 14, preferably assured by downward flexure of the flange through the bending of the upwardly and inwardly extending wall portion 12. The cap and sealing gasket are then transferred with the container to a sealing station where the sealing ply 34 is heat activated to cause the gasket 32 to be semi-permanently peelably affixed to flange 14.

There is minimal frictional contact between the underside of cap top 22 and the upper plane of disk 32 such that the cap 20 can be unscrewed from closure mouth 10 with relatively low torque. As the cap is unthreaded at points 18 from the annular mouth of the closure wall 10, the lugs or beads are overrided by the lateral free edge of disk-shaped gasket 32. With continued unscrewing, the lug portions 38 snap clear the free edge of sealing gasket 32 and the cap is removed. Therafter, the container is opened by gripping the gasket and peeling it from flange 14; thereafter the cap is rethreaded on the base over the closure opening and the container contents may be dispensed through orifice 28 and nozzle 30.

The annular recess 40 serves to station the mouth of flexible container 16 at a fixed vertical height such that the sealing cap integration function and adhesive activation can be consistently performed, this despite the relatively flexible nature of the bellows-shaped container.

Cap 20 can be removed from the container mouth with a low-torque twist whether the cap is retained by a conventional thread or a bayonet joint. The minimal amount of friction resisting removal achieved by the compressed state of the gasket 32 bearing against the underside of cap top 22 and stressing threads 18 is well within the manipulative ease of one's hand when employed to uncap the container. On the other hand, the container per se is adequately sealed without having to mount the gasket conventionally and more or less permanently within the cap. This versatility is achieved through the simple expedient of temporarily seating the gasket within the cap and then transferring the gasket to the cap in place to the flange or other wall portion adapted to receive the gasket seal and seat same.

Claims

What is claimed is:

1. In a closure comprising in combination a cap having a cylindrical side wall and a top wall, a heat activatable sealing gasket removably seated within said cap having the gasket face proximate the cap top wall adapted to rotate axially relative thereto and adapted to be seated and induction sealed upon a closure mouth, and a closure mouth having a flexible inwardly directed flange receiving said cap and sealing gasket and adapted to be deflected axially as the cap is screwed on the closure:

a. means mounted within the cylindrical cap side wall obstructing removal of the gasket from the cap and serving to loosely and temporarily seat the gasket within the cap as it is seated on the closure mouth preparatory to activating said gasket, said cap side wall being threadably engaged to the outer side of the closure mouth;

b. the outer free edge of said gasket being of a diameter such that it is greater than that of the obstructing means whereby said gasket is retained within said cap but also being such that it may override the obstructing means in cap removal by twisting the cap relative to the closure mouth to disengage the threaded engagement therebetween;

c. said outer free edge of the gasket projecting beyond the perimeter of the closure mouth and being sufficiently flexible to permit passage of said cap's obstructing means as it is moved axially to override said gasket upon twisting the cap;

d. said gasket in the activated state being induction-sealed to said closure mouth with an adhesion sufficient to seal the closure mouth and also to remain seated on said mouth as the obstructing means of said cap are moved axially to override the flexible outer free edge of said gasket.

2. The closure of claim 1 wherein the closure mouth is composed of a thermoplastic material adapted to form a bond with a sealing ply located on the underside of said gasket.

3. The closure of claim 2 wherein said gasket comprises a sealing ply coat and a foil ply coated by the sealing ply and adapted to be heated and thereby activate the sealing ply.

4. The closure of claim 3 wherein the closure mouth is formed of deformable thermoplastic composition adapted to be heated and thereby adhere to the sealing ply upon activation thereof.

5. The closure of claim 1 wherein the obstructing means is a series of interrupted annular beads or lugs formed in the cylindrical side wall of the cap, the inner perimeter of the obstruction in relation to the outer free edge of the gasket being sufficient to initially retain the gasket within the cap prior to activation of a sealing ply but also being insufficient to permanently obstruct removal of the cap from the closure mouth and permitting the annular contacting surfaces thereof to override the outer free edge of the gasket.

6. The closure of claim 5 wherein the obstructing means have annular gasket-engaging surfaces that slope downwardly and inwardly from the cylindrical side wall of the cap and permit a gradual flexing of the perimeter of the cap side wall to override the gasket as the cap is removed.

7. The closure of claim 5 wherein the closure mouth has a flange which abuts the face of the sealing ply in substantial face-to-face planar relation and is resiliently urged thereagainst prior to activation of the sealing ply.

8. The closure of claim 7 wherein the flange in the unflexed and unsealed position prior to application of the cap thereon projects upwardly and inwardly at a minor acute angle to a plane normal to the longitudinal axis of the closure mouth and is adapted upon application of the closure cap and the disk seated therewithin to be flexed downwardly and resiliently to assure a face-to-face abutting planar relation between the gasket and the flange.

9. The closure of claim 8 wherein the free edge of the gasket projects sufficiently outwardly beyond the perimeter of the closure mouth to have sufficient flexibility to permit the annular obstructing means to overrids said free edge by flexure of said gasket at its unsupported regions.

10. The closure of claim 5 wherein said obstruction means is an interrupted annular bead circumscribing the interior of the cap's side wall and projecting outwardly therefrom to have an internal diameter less than the external diameter of the sealing gasket.

11. The method of sealing a closure comprising a cap having a cylindrical threaded side wall and top wall having a sealing gasket therewithin and a closure mouth having a threaded sidewall and adapted to receive said gasket in seal-tight relation, said gasket having the face proximate the cap top wall rotatable relative thereto, the closure mouth having a flexible inwardly directed flange adapted to be deflected axially through the intermediation of the gasket as the cap is screwed on the closure, said cap having means for obstructing removal of the gasket temporarily seated with said cap, said gasket fitting loosely within said cap so as to be axially displaceable therein and having a heat activatable surface adapted to adhere upon activation to the flange of said closure mouth, said gasket having a flexible outer portion adapted to flex to permit opening of the closure by removal of the cap and permitting passage of the obstructing means over the free edge of said gasket which comprises:

a. seating said gasket within said cap with the sealing ply exposed;

b. screwing said cap on to said closure mouth to flex the closure flange axially through the intermediation of said gasket; and

c. activating the sealing ply on said gasket by induction heating to effectively transfer said gasket from its temporary seat within said cap to a permanent seat on said closure mouth.