Fused Container Closure And Means Facilitating Removal Of The Same

Abstract

The disclosure is directed to a container having a pouring neck and a closure member covering and fused to the peripheral lip surrounding the pouring opening to provide a tamperproof sealed container. The portion of the container neck and peripheral lip are reduced to the juncture thereof to facilitate grasping of the closure member to remove the same.

Description

The present invention relates to hermetically sealed tamperproof plastic containers wherein a plastic closure is integrally fusion bonded across the container neck opening. Exemplary of such prior tamperproof containers is that described in U.S. Pat. No. 2,937,481.

The aforesaid patent discloses a plastic bottle having a plastic closure member in the form of a diaphragm fusion bonded across the neck opening thereof. After filling of the bottle the periphery of the plastic diaphragm is maintained in pressure engagement with the periphery of the pouring lip and the same is inductively heated to fuse the bottle and diaphragm. In order to insure proper placement of the plastic diaphragm, appropriate heat transfer properties and pressure engagement of the diaphragm with the bottle lip, a laminated assembly is formed with the plastic diaphragm which includes overlying metal and paper discs in the form illustrated and for the purpose described in the aforesaid patent. The laminated disc structure is then placed in sealing position over the bottle lip and a conventional screw cap holds the assembly in place with the periphery of the plastic diaphragm in pressure engagement with the pouring lip. The laminated structure is normally supplied in sheet form and the laminated discs are struck therefrom as a unit handled assemblage.

All of the foregoing is disclosed in the aforesaid patent and reference may be had thereto for further details regarding the various materials that may be utilized in the practice of the present invention as well as the precise method of forming the fusion bond by induction heating. The improvement resident in the present invention is a reduction in thickness of the container neck wall and pouring lip at the junction thereof to facilitate grasping of the closure member to remove the same.

Tamperproof containers of the type described in the aforesaid patent have not enjoyed widespread commercial success primarily because of the difficulty involved in removing the fusion-bonded closure. In the case of the prior art containers it has been necessary to rupture the seal, as opposed to peeling it off, because there was not a sufficient peripheral area of the closure exposed to permit grasping of the same. In the case of a widely used and much handled commodity such as a milk container, for example, the disadvantages in the unsightly appearance and deformed pouring opening created by rupturing the closure are obvious.

The use of an oversize closure member to present a larger peripheral grasping area whereby the same might be peeled from the pouring lip would necessarily require that the backing discs of metal and paper also be oversize since the laminate is struck from a single sheet which is clearly impractical for the reason that an oversize assemblage would not fit within a properly sized screw cap and would, further, result in bonding of the extended peripheral portion of the closure to the outer walls of the neck during the inductive heating step.

Accordingly, it is an object of the invention to provide a tamperproof container wherein a fusion-bonded closure member may be readily peeled from the neck opening.

Further objects are to provide a tamperproof container possessing the pouring characteristics of conventional containers employing nonintegral closures and to avoid the unsightly appearance of the ragged edges of a ruptured closure adherent to the pouring lip.

The foregoing objects are achieved by locally reducing the thickness of a container neck wall and pouring lip at the juncture thereof whereby the fusion-bonded closure may be grasped and peeled off.

The invention may assume a variety of forms and in the case, for example, of a generally cylindrical container neck may range from a complete circumferential reduction in neck wall and lip thickness to a more localized area of wall and lip reduction comprising the formation of a notch extending throughout less than 90.degree. of the circumferential extent of the neck wall.

The various notch configurations herein disclosed may vary widely in form and extent, the important factor being that for various size containers and fabricating procedures a particular notch configuration may present particular advantages though all of such notches as well as the complete circumferential reduction in wall and lip thickness serve the function of exposing a sufficiently large peripheral or localized area of the closure to be grasped and peeled from the container neck opening while yet insuring that the neck wall thickness at the pouring lip is sufficient to insure structural integrity and the formation of a fusion bond with the closure member.

In the drawings:

FIG. 1 is a broken perspective view of a plastic container having a neck whose wall and lip thickness are reduced at the juncture thereof throughout their peripheral extent;

FIG. 2 is a broken cross-sectional view of a bottle neck, constructed as in FIG. 1, as it would appear prior to a fusion bonding step;

FIG. 3 is a view similar to FIG. 2 after completion of the bonding step;

FIG. 4 is a partial perspective view of a container neck wall exhibiting a tapered notch;

FIG. 5 is a sectional view, partially broken away, taken along line 5--5 of FIG. 4;

FIG. 6 is a partial perspective view of a container neck wall exhibiting a square notch;

FIG. 7 is a sectional view taken along line 7--7 of FIG. 6;

FIG. 8 is a partial perspective view of a container neck wall exhibiting a radiused notch;

FIG. 9 is a sectional view taken along line 9--9 of FIG. 8;

FIG. 10 is a partial perspective view of a container neck wall in which is formed an axially elongated notch interrupting the thread thereon;

FIG. 11 is a partial perspective view of a container neck wall provided with a modified tapered notch wherein the end walls thereof are flared; and

FIG. 12 is a broken top plan view of the container neck shown in FIG. 11 illustrating the flared notch end walls.

In FIG. 1 is illustrated a first container neck wall and lip configuration that may be utilized in the practice of the invention and FIGS. 2 and 3 depict subsequent stages of assembly in the formation of an integrally bonded closure member with the neck structure shown in FIG. 1.

The plastic container 10 depicted in FIG. 1 is provided with an upstanding neck 12 terminating in a peripheral pouring lip 14 defining a pouring opening. The pouring opening is adapted to be hermetically sealed by a plastic closure 16 herein illustrated in the form of a circular diaphragm having a diameter substantially equal to the outer diameter of the neck wall. The outer surface of the neck wall is provided with a helical thread 18 for the reception of a conventional screw cap 20 which, in addition to serving as a removable closure after sealed closure 16 is removed, provides the necessary positioning and pressure engagement of closure member 16 with peripheral lip 14 during the formation of a fusion bond therebetween. Thus, as described in U.S. Pat. No. 2,937,481, a circular laminated assembly 21 consisting of plastic closure 16, an intermediate metallic disc 22, preferably in the form of aluminum foil or the like and a cushioning disc member 23 such as paper or the like is retained on lip 14 with diaphragm 16 in pressure engagement therewith as indicated in FIG. 2 prior to an inductive heating step to effect the fusion of closure 16 to lip 14 indicated in FIG. 3.

The tamperproof, hermetically sealed container is then ready for marketing with the neck assemblage as indicated in FIG. 3. When the container is to be opened the screw cap is removed and paper disc 23 normally adheres thereto leaving plastic closure 16 and its overlying disc or foil 22 exposed. The foil disc is normally peeled from the container opening along with plastic closure 16.

In order to provide the necessary peripheral grasping surface to enable a consumer to grasp and peel closure member 16 from the neck opening, the thickness of neck wall 12 and pouring lip 14 have been reduced throughout the entire peripheral extent of the radially outermost juncture thereof. In the FIG. 1 embodiment this reduction in wall and lip thickness consists of a circumferentially continuous bevel or taper 24.

The remaining embodiments, depicted in FIG. 4-12, rely on a single notch to provide the desired reduction in wall and lip thickness; such notch extending throughout a sufficient peripheral extent of the pouring lip to enable one to grasp and remove the closure. The notched configuration has the advantage that a greater surface area of contact may be obtained between the lip and closure to facilitate the fusion-bonding operation.

As will be obvious, a wide variety of notch configurations may be utilized in the practice of the invention. Thus, the notch configurations shown in FIGS. 4, 6 and 8 terminate well above the uppermost extent of helical thread 18 and exhibit tapered, perpendicular and curvilinear surfaces 26, 28, 30 in cross section, respectively, extending between spaced end walls 32, 34, 36 which end walls may extend substantially perpendicular to a tangent to the circumference of neck 12. The embodiment shown in FIG. 10 is similar to that of FIG. 4 but wherein the tapered notch is greatly elongated in the direction of the container axis to interrupt helical thread 18. The FIG. 10 embodiment not only affords more ready access to the undersurface of a fusion-bonded closure but also provides an obvious visual indication of the closure grasping location. The bottle neck shown in FIGS. 11 and 12 also exhibits a tapered notch similar to that of FIG. 4 but wherein the sidewalls 38 are flared. This latter configuration permits the use of a notch having a lesser peripheral extent than those previously described while yet providing ready gripping access to the underside of the closure.

Each of the container neck configurations is assembled with its closure member and fusion bonded in the same manner as described in connection with the FIG. 1 embodiment. The extent of neck wall and lip reduction, in each case, is normally greater than half the thickness of neck 12 and may advantageously comprise a wall reduction of 65- 75 percent when measured at the plane of the pouring lip. In general, it will be desirable to effect a maximum reduction in wall thickness consistent with maintenance of the structural integrity of neck wall 12.

Claims

We claim:

1. In a sealed plastic container having a peripheral wall defining a neck terminating in a peripheral lip with a plastic closure fused to said lip about the periphery thereof, the improvement comprising; means providing grasping access to said closure for peeling the closure off the lip, said means comprising at least a portion of said neck wall and said lip being reduced in thickness at the juncture thereof.

2. The sealed container of claim 1 wherein the thickness of said neck wall at the reduced portion thereof is less than half the thickness of the remainder of said neck wall.

3. The sealed container of claim 1 wherein said reduced portion is defined by a bevel extending throughout the peripheral extent of said juncture.

4. The sealed container of claim 1 wherein the reduced portion of said neck wall and lip is confined to substantially less than half the peripheral extent of the juncture thereof.

5. The sealed container of claim 4 wherein said reduced portion comprises a notch defined between spaced end walls.

6. The sealed container of claim 5 wherein said notch presents a planar surface in cross section.

7. The sealed container of claim 5 wherein said notch presents a curvilinear surface in cross section.

8. The sealed container of claim 5 wherein said notch presents substantially perpendicular surfaces in cross section.

9. The sealed container of claim 5 wherein said end walls are substantially perpendicular to respective tangents to said neck wall.

10. The sealed container of claim 5 wherein said end walls are flared.

11. The sealed container of claim 5 wherein said neck wall includes an external thread spaced from said lip and said notch terminating short of said thread.

12. The sealed container of claim 5 wherein said neck wall includes an external thread spaced from said lip and said notch interrupts said thread.

13. The sealed container of claim 1 wherein the reduction in neck wall thickness extends inwardly from the outer neck wall surface to intersect said lip and terminate short of the inner neck wall surface.

14. The sealed container of claim 13 wherein the thickness of said neck wall at the reduced portion thereof intersecting said lip is less than half the thickness of the remainder of said neck wall.

15. The sealed container of claim 14 wherein the reduced neck wall portion provides a nonconvex surface.

16. The sealed container of claim 1 wherein the closure is autogenously bonded to the lip.

17. The sealed container of claim 1 wherein the closure extends no farther than the surface of the neck wall of unreduced thickness.