CA1168621A

CA1168621A - Closure

Info

Publication number: CA1168621A
Application number: CA000392976A
Authority: CA
Inventors: Efrem M. Ostrowsky; Werner R. Luenser
Original assignee: Precise TMP Inc
Current assignee: Precise TMP Inc
Priority date: 1980-12-22
Filing date: 1981-12-22
Publication date: 1984-06-05
Also published as: EP0055916B1; EP0067221A1; JPS57501998A; AU576885B2; BR8108921A; DE3177214D1; AU544147B2; AU8083582A; AU4616285A; EP0055916A1; WO1982002182A1

Abstract

CLOSURE
Abstract of Disclosure A closure for fitment to the threaded neck of a con-tainer is disclosed. The closure is especially adapted for use in packaging products such as carbonated beverages. The closure has a circular top wall and an annular skirt downwardly depending therefrom. The skirt carries about its inside surface a closure thread for cooperation with the neck thread of the container. A circular, flexible resilient liner is positioned against but rotatable with respect to the inside surface of the top wall and has a diameter greater than the outside diameter of the container lip which defines the container mouth. There is provided an annular projection which is located adjacent the inside intersection of the top wall and the skirt. This projec-tion has a configuration whereby it presses the liner on the outside edge of the container lip to form a gas-tight seal when the closure is fitted onto the container.

Description

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CLOs~n~

BacXground of the Invention For many years it has been general practic~ to utili~e bottles ~hich are sealed by means of the so-called crown closure to package products which effect a positive pxessure in the bottles. Exemplar~ of such products are carbonated bevera~es such as beer.' The crown closure is commonly made of tinolate and its fluted slirtis engaged under a peripheral rib ~Jhich e~tends around the neck of the bottle in close pro~imity to its mouth. , The cro~n closure suffers from two defects, namely, it requires a special tool to remove it from the bottle 2nd it cannot be used to reclose the bottle. In recent years non-returnable bottles have come into more yeneral use and these have been adopted for some carbonated beverages. When non-returnable bottles are adopted, it is practicable to adop~ the most con~
venient fonm of closure consistent with economy in price. The most widely employed form o, non-returnable bottl2 system for carbonated beverages has employed a bottle with an externally screw-threaded neck, having a cylindrical sealing surface between the top of the bottle and the start of the thread. With this bottle there has been employed a closure in the form of an alumi-num shell having a gasket covering the inner surface o the top of the shell which ~orms a sealin~ liner. The diameter of the skirt of the closure shell is sufficiently large to fit over the thread on the bottle neck at the ma~imum si~e allowed by the ran~e o tolerances set out in the specification of the neck finish of the bottle. The skirt o khis sllell is deformed by a ..
. ~

-~1'` li68621 thrc~d-rolling opera~ion carried ou~ in known way ~o brinq it int~
ensagement with ~he thread on the bottlc neck.
~ hile such aluminum closures have receivca wide accc~t- ¦
ance, therc is an economic problem due to the high cost of alumi num. ~luminum's high cost is dircctly proportional to the ever rising high cost of ener~y as aluminum production is energy intensive.
A hig~ly promising alternative to the use of aluminum closures is the use of closures made of thermoplastic material.
Such materials are becoming more and more economically ~avorable when compared to aluminum. Exemplary of such closures is the one sho~.~n in U. S. 3,067,900. As desirab]e as it may be to use thermo-¦
plastic material, there is one serious drawback, i.e., the ten- ¦
dency of thermoplastic closures to lose their seal as positive pressure builds in the bottle. Since the seal is made by the closure making sealing contact with the bottle, the loss of se~l is generally due to the closure flexing, as the pressure bullds, resulting in the closure structure being distorted and pulled away from the bottle. To prevent flexing, it is possible to select a v~ry rigid thermoplastic material. However, the seal sought to be obtained when usin~ such materials is not always initially achieved as the rigidity of the material will not allow th~ sealing configuration to follow structural variations which a~e co~nonly present on the bottles. Also such rigid materials a~e often very expensive. Less expensive materials could be used if the flexing portion of the closure was made thlcker to achieve the rigidity sought. But, as is obvious, the cost of such a thicker closure rises in direct proportion to the amount of material used and renders such closures commercially unacce~table, .

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With the economic realities in mind, it would be highly desirable to redesign the thinner commercial closures used today so that the flexing phenomena will not cause loss of seal but rather will be utilized to increase the fidelity of seal as internal container pressures build.
Therefore, it is an object of this invention to provide an inexpensive thermoplastic closure which is capable of maintaining a seal in response to a positive pressure in a container such as a bottle.
According to the present invention there is provided a thermoplastic closure for fitment to a container having a threaded neck terminating in a lip which defines an open mouth. The closure has a circular top wall with an annular skirt downwardly depending from the top wall, the skirt having about its inside surface a closure thread for cooperating with the neck to achieve the fitment. A
circular, flexible resilient liner is positioned adjacent the top wall and has a diameter greater than the outside diameter of the lip, the liner being free to rotate with respect to the circular top wall. An annular means is located adjacent the inside intersection of the top wall and the skirt, the annular means having a configuration so that the annular means pxesses the liner around the outside edge of the lip to form a gas-tight seal when the closure is fitted on the container.
~ccording to one embodiment of the invention, there is additionally provided a retaining ring about the inside surface of the skirt which is positioned below the annular structure but above the closure thread. This retaining righ prevents the liner from moving down to the closure thread. Thus, if the liner should fall away from the top wall the retaining ring will prevent i-t from being .~l .

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separated from the remainder of the closure.
T~ aid in maintenance of the position of -the liner in its sealing position with respect to the con-tainer there may be provided an annular ~ab which projects downward from the top wall. This tab will engage the liner and prevent any lateral movement thereof.
It is believed, the closure of this invention is not restricted to this theory, but that by having the liner wrapped around the outside edge of -the container lip a ~as-tight saal is maintained even upon upward flexure of the top wall which flexure is caused by positive pressure build-up in the container. When the closure is originally fitted to the container there are two principal sealing areas~
i.e., there is a seal formed between the liner and the top of the container lip and a second seal formed between the outside edge of the lip and the liner. When the closure top wall begins to flex upwardly in response to positive pressure in the container the first seal between the liner and the top of the contai~ex lip is compromised as the liner is no longer as well supported due to upward flex of the top wall. However, due to the unique configuration of the closure of this invention, the upward flexing of the top wall increases the fidelity of the second seal as that portion of the liner which is wrapped around the outside edge of the container lip is pressed into a tighter relationship with the outside edge. This is due to the fact that the flexing of the top wall causes the upper portion of the container sidewall to be pulled inwardly. ~s the sidewall upper portion is pulled inwardly the annular structure presses more firmly against the liner thereby increasin~ the fidelity of the seal. Thus, the closure of this invention utilizes the heretofore undesirable flexing of the top wall to - - , ~ ' ~ , , :

increase the fi~elity of the seal. This is airectly opposite to present-day closures in which the upward flexing of the top wall results in a reduction in seal ~idelity.
There are different configurations which the annular structure can have to achieve the above-mentioned seal between the liner and the outside edge of the container lip. For example, the annular structure can have a configuration, when viewed in cross-section, which has a horizontal portion, a vertical portion, and a convex portion, the convex portion connecting the horizontal portion and the vertical portion one to the other. When utilizing this configuration, there is a concentration of sealing pressure at a point near the center of the convex portion. Another configuration is one in ~?hich the annular structure is a convex bead. By utilizing a convex bead the pressure exerted by the annular structure is distributed over a wider area of the liner than is the case with the just-described annular . ..
structure having the horizontal, vertical and convex portions. Another annular structure which can be utilized is one in which the structure is a concave groove having a radius at least equal to the radius of the convex outside edge of the lip.
There are other configurations which may be utilized, the only requirement being that the liner be pressed into a position around the outside edge of the lip and that the configuration results in an increasing of pressure between the liner and the outside edge of the lip as the top of the closure flexes upward in response to positive pressure in the container. The freedom of the liner to rotate results in the liner being able to achieve essentially a single position on the container lip even though the closure continues to rotate as it is tightened to the ' , 11sii86Zl container~ I th~ lin~r was fixed to the closure, thc o~osite effect would occur aS ~he liner would have to rot~tc alon~ with the closure as it is tighter~ed.to the container. Li.ner rotation ~lith respect to the container-lip results in the liner bcing rubbed ovcr .the lip surface as it rotates with the closure. Such liner-lip r~bbin~ is di~advantageous as each irregulariiy in the container lip will cause its particular liner defo~ation and ;
such deformations will, when the closure reaches its fin~l tiyhtened ~osition, almost always not coincide with the Particular lip irregularity,~}lich caused the liner defor~ation. The result of this non-coincidence is deleterious to seal fidelity as the contacting liner-lip sealing surfaces are not in as intimate contaCt as ~ould be possible if the liner deformation matched the lip irregularity ~hich caused it. On the other han~, when ¦
the liner is free to rotate with respect to the closure and is not forced to rotate about the container lip, the liner is simply pressed do~nwardly.onto the container lip and each liner deor~a-tion caused by a particular lip irregularity will coincide with the irregularity. With matching o~ the liner deformations to the lip ir-e~ularities a highly intimâte contact is made and seal idelity is Preserved. Achievement of the non-rotation of the ¦
liner with respect to the container lip is a result of the liner ~re~do~ vis-a-vis the rest o the closure and the friction between the liner and lip be'ng greater than the Eriction between the elosure and the liner. This difference in friction can be ~ttributed to a higher coefficient of friction for the liner-lip eontaet than for the liner-elosure contact and/or a more irre~ular lip sur ace than the closure surfaee contacted by the liner~
The lin r utili~ed should al,so be flexible and resiiien~..
Furthermore, sinee the closurc of this invention is to be uti].izcd ~1 ~ 686Z~

on either glass or plastic contairlcrs, the lincr should be ~a~e o~ a ~at~rial which is compatible ~ith the container to which th~
closure is a.tached. For examp~e, liners made of ~aterials which stick to the container lip should be avoided as unscrcT~ing the S closure from th~ container will be difficult and, even if achieved, could result in tearing of the liner~ It has been ~ound that liners made o~ an ethylene vinyl acetate copolymer ~ives superio~ results on both glass and plastic containers.
Further, such liners are acceptable from a toxicological and odor standpoint when the container is utilized to hold consumable ~roducts such as ~arbonated ~everages, beer, etc. If the con~ I
~ainer ~s to hold a non-consumable, other materials may be utilized such as polyvinyl chloride. To help reduce the torque required to remove the closure from the container it may be desirable, when the liner is of a thermoplastic material,to add an additive which will increase the liner's lu~ricity character- ¦
istics. A slip additive such as synihetic wax or fatty amide ~ave been found very useful for this purpose.
The remainder of the closure can be made of any moldable her~o~las.ic m2terial which will provide the prior-described ~haracteristics for the top wall of the closure. EIowever, the hermoplastic material should not be so 1e~ible that, under ~uilding positive container pressure, the sidewall of the closure ill ~le:~ outwardly resulting in the closure threads jumping over ~` 25 he container threads, It has been found that a hi~hly preferred thermoplastic material is polypropylene. Other thermoplastic naterials which may be useful are polyethylene terephthalate, hi~h I
~ensity polyethylene~ nylon, polyvinyl chloride, etc. Other mate- ¦
^ials which would be useful are well ~nown to those s~illed in the ~rt given the preceding identified criteria.

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Thcse and other fcatures contributin~3 to satis~action in use and cconcmy in manufacture will be mor~ fully und~rstood when taken in c~nnection rlith the followin.~ description of preferred embodiments and thc accompanying drawings in which S identical n~merals refer to the identical parts and in which:
FIGURE 1 is a partial sectional view showing a closure of this invention fitted , to a COIItainer neck;
FIGURE 2 is a partial sectional view o the 10' closure shown in Figure 1 under the influence or a positive pressure in the container;
FIGURE 3 is an enlarged sectional view of a portion of the container and closure 15shown in Figure 2;
FIGURE 4 lS a sectional view taken along section lines 4-4 in Figure 1;
FIGURE 5 is a sectional view taken along section lines 5-5 in Figure 2;
20 .FIGU~E 6 is an enlarged sectional view showing a second embodiment of this invèntion; and FIGURE 7 is an enlarged sectional view sho~ing a third embodiment of this invention.
, ~, . .' escription of the Pre~erred_Embodiments Referring now to Figures 1-4, it can be seen that a closure, generally designated by the numeral'l0, is fitted to a container neck, generally designated by the numeral 8~ Container neck 8 has about its outside surface adjacent its upper end heli-cal thread 26. At the terminal end of container nec~ 8 there is ~8-6~L
mou-th through which the container contents are dispensed.
Lip 15 defines -the boundaries of the container mouth. As mentioned previously, the container with which closure 10 is utilized can be made of any suitable material, e.g., glass or a thermoplastic material such as polyethylene terephthalate, polyethylene, polyvinyl chloride, atc.
Closure 10 has an annular top wall 12 with a sidewall 14 downwardly depending therefrom. About the inside surface of sidewall 14 there is provided helical closure thread 16 which is of a design whereby it cooperates with container helical thread 26 to achieve fitment of closure 10 to the container. In close proximity to top wall 20 there is provided liner 18. Liner 18 has a diameter greater than the outside diameter of container neck 8 measured at the container mouth.
By having a greater diameter, line 18 will be able to extend around the outside edge 28 of lip 15 to effect the seal o~ this invention. Liner 18 is prevented from moving away from top ! wall 12 by means of annular ring 24. Annular ring 24 may be-continuous or discontinuous. Attention is drawn to Figure S
~0 in which a discontinuous annular retaining xing 24 is shown.
Projecting downwardly from top wall 12 there is provided annular tab 22. Annular tab 22 has a triangular shape when viewed in cross-section. See Figures 3, 6 and 7. As mentioned previously, annular tab ~2 is utilized to insure that liner 18 does not move laterally during the buildup ofinternal container pressure.
Note that annular tab 22 is positioned so that it is over lip 15. By having annular tab 22 so positioned, it is assured that annular tab 22 will obtain a grip on liner 18 by penetration.
~ocated adjacent the inside intersection of to~ wall 12 and downwardly depending sidewall 14 there is provided annular _ 9 _ jrc~

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a~ 20. ,~n cnlargcd vic~l o~ t}lc cross-scction of arlnular hcad 20 is shown in Figurc 3. ~s can be seen in thls coniguration, annul~r ~ead 20 has a horizontal portion 21 and a vertical por- ¦
tion 23. Con~cx portion 25 conne~ts horizontal portlon 21 to ~¦
vcrtical portion 23. Convex portion 25 is preferably opposite the outside ed~e 28 of lip 15.
In Fi~ures 6 and 7, there is sho~in other configurations which may be utilized in place oE annular bead 20. In Figure 6 annular bead dO is used in place of annular bead 20. Annular bead 40 has, for all practical purposes, no horizontal or vertical portions, but rather is simply a convex head. Another configura- !
tion is shown in Figure 7 in which the bead presents a concave profile when viewed in cross-section. This concave bead is labeled 42 and is shown in Figure 7. When utilizing concave bead 42 it is preferable that the outside edge 28 of li~ 15 be convex so that liner 18 is nested between concave bead 42 and outside edge 28.
Figures 3, 6 and 7 show that the annular beads press against liner 18 to cause it to wrap around outside edge 28 or lip 15. When top wall 12 is flexed upwards due to pressure in the container the intersection of top wall 12 and sidewall 14 is brought inwardly towards outside edge 28. As a result of this movement, the annular bead, since it is integral with the inter-s~ction, will also move int~ardly towards outside edge 28. Thus, liner 18 is pressed by the annular bead so that it wraps around outside edge 28. The greater the flexure o top wall 12 the ~reater the inward movement o the before-mentioned intersection and the annular bead, and the further the annular bead is forced to move inwardly the grea-ter the pressure it exerts on liner 18.
It can therefore be seen that the seal between liner 18 and outside edge 28 is increased as the pressure grow~, since the top wall fl~xes in respons~ to the amoun~ of pressure present.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A thermoplastic closure for fitment to a container having a threaded neck terminating in a lip which defines an open mouth, said closure comprising:
a. a circular top wall;
b. an annular skirt downwardly depending from said top wall, said skirt having about its inside surface a closure thread for cooperation with said neck thread to achieve said fitment;
c. a circular, flexible resilient liner positioned adjacent said top wall and having a diameter greater than the outside diameter of said lip, said liner being free to rotate with respect to said circular top wall; and d. annular means located adjacent the inside intersection of said top wall and said skirt, said annular means having a configuration whereby said annular means presses said liner around the outside edge of said lip to form a gas-tight seal when said closure is fitted on said container.

~ . The closure of Claim 1 wherein said annular means is an annular bead having a configuration, when viewed in cross-section, which has a horizontal portion, a vertical portion and a convex portion, said convex portion connecting said horizontal portion and said vertical portion one to the other.

3. The closure of Claim 1 wherein said annular means is a convex bead.

4. The closure of Claim 1 wherein said outside edge of said lip is convex and wherein said annular means is a concave groove.

5. The closure of Claims 1, 2 or 3 wherein said closure additionally has a retaining means about the inside surface of said skirt downwardly positioned below said annular means but above said closure thread for preventing said liner from moving down to said closure thread.

6. The closure of Claims 1, 2 or 3 wherein said closure additionally has an annular tab downwardly projecting from said top wall for engaging said liner to prevent said liner from pulling away from its seal position.

7. The closure of Claims 1, 2 or 3 wherein said closure is made of polypropylene.

8. The closure of Claims 1, 2 or 3 wherein said liner is an ethylene vinyl acetate copolymer.

9. The closure of Claims 1, 2 or 3 wherein said closure additionally has a retaining means about the inside surface of said skirt downwardly positioned below said annular means but above said closure thread for preventing said liner from moving down to said closure thread and said closure additionally has an annular tab downwardly projecting from said top wall for engaging said liner to prevent said liner from pulling away from its seal position.

10. The closure of Claims 1, 2 or 3 wherein said closure is made of polypropylene and said liner is an ethylene-vinyl acetate copolymer.