GB2186558A

GB2186558A - Container closure

Info

Publication number: GB2186558A
Application number: GB08603877A
Authority: GB
Inventors: Kenneth Martin Sinnott; Noel Ernest Davenport; Geoffrey Richard Thwaites
Original assignee: WR Grace and Co
Current assignee: WR Grace and Co
Priority date: 1986-02-17
Filing date: 1986-02-17
Publication date: 1987-08-19
Also published as: EP0233722A2; ZA87746B; IN171254B; NZ219099A; JPS62251357A; BR8700702A; AU6867687A; GB8603877D0; EP0233722A3

Abstract

A jar (1) has its closure (2) sealingly applied by means of a downthrust to compress a gasket (3). The closure is retained by detent means (not shown). The head load applied to the closure of that jar as a result of subsequent stacking of other similar jars on top of the jar in question is limited by engagement of stop means, in this case, the rim (6) of the closure with an external rib (5) of the jar, so that there is no possibility of permanent deformation of the gasket (3) imparted during such stacking. The arrangement is such that the closure (2) can be applied by simple downthrust, without the need for a twisting chuck, even where the detent means comprise screwthreads. <IMAGE>

Description

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SPECIFICATION Container closure

5 The present invention relatestoacontainerclosure of the type including a resilient sealing memberfor yieidably engaging a container opening to seal against the container.

When sealingly closing containers, it isfrequently 10 the practice to rely on resilient deformation of a sealing member of the closure, as the closure is pressed home into position on the container. For example, the closure may be pre-threaded and the closing action may employ rotation of the closure in which 15 case the pressing of the closure against the container occurs as it is being screwed onto the container. Another possibility is for the closing action to employs snap-fit action which relieson resilient deformation of at least one of the closure and the containerto 20 allow a detent formation on one or other of these two elements to accept the closure onto the container and then to resist subsequent accidental removal from the container. There is also the possibility of combinations of these two systems, for example 25 where the detent elements comprise threads which can normally be undone by unscrewing but which are not so rigid as to prevent the closure from being applied to the container by a simple thrust onto the container opening, without twisting. 30 The resilient sealing memberfrequently comprises a gasket of a material which is softer than the material of the closure itself, thereby allowing the gasketto deform resiliently to achieve a sealing effect.

35 A problem exists where the containers are, after closing, subjected to handling giving rise to still further deformation of the resilient sealing member, for example by the containers being stacked in columns such that the cumulative weight of the column 40 of loaded containers on, say, the closure of the bottom container results in ]the resilient sealing member being deformed to a much greaterextent than was the case during the application of the closure to that bottom container. Where, for ex-45 ample, the closing head load (theforceto apply the closure to the container) is relatively small and is likely to be a mere fraction of the head load subsequently applied on the closure, the more pronounced deformation to which the resilient sealing member is 50 subject when stacked in this way may give rise to some permanent deformation (forexamplethrough "creep"), such that when the head load is removed, the result of the permanent deformation of the resilient sealing member of the closure may be such 55 that there is no longer any residue of the "after closing" deformation of the resilient sealing member of that closure and consequently the ability of the resilient sealing memberto seal can be totally lost.

Generally, the problem of excessive head load 60 subsequenttoclosingapplieswhenthesubsequent head load exceeds the residual load to which the sealing member remains subjected immediately after closing.

One solution to this problem can be appreciated 65 from European Patent No. 0112 692 in which a pail is equipped with a lid which is held in place by a screw action by virtue of which projections on the rim of the pail are able to enter downwardly open recesses in the pail lid and subsequently as the pail lid is 70 screwed in place the projections move into a region of the recess of limited vertical extent such thatthe pail lid is eventually locked in place by trapping of the projection in the "limited vertical extent" region of the recess. This arrangement locks the lid against 75 movement axially of the container and consequently no matter how great a head load is subsequently applied to the closure, the hollow O-ring type of sealing gasket used will be strained to substantially only theamountapplied during the closing load. 80 Such a system has the disadvantages that the removal of the pail lid requires quite a high twisting force to rotate the lid, and closure of the pail can only be effected with a twisting chuck. It is advantageous forthe containerto be capable of closing by a pure 85 head load, thereby avoiding the need for a twisting chuck.

Accordingly, one aspect of the present invention provides in combination a container and a closure, theclosureincluding:-a resilient sealing memberto 90 be deformed upon application of the closure to the containerto provide a sealing force applied by the resilient sealing member against the container, and stop meansfor limiting axial movement of the closure relative to the container in a sense which in-95 creases deformation of the resilient sealing member, the arrangement being such thatthe stop means allows a required closing axially directed head load to be applied to close the closure onto the container, but subsequently prevents excessive head load from 100 being applied to the resilient sealing member.

Another aspect of the invention provides a method of closing a container comprising applying a closure to an opening of the container principally by means ofdownthrustofthe closure against the container 105 opening, limiting the closing head load to a value which is enough to ensure sealing of the container by means of the closure by detent engagement of the closure on the container opening, and relying on a stop formation on the closure and/or the containerto 110 prevent any substantial increasing of the head load during the life of the closed container.

Afurther aspect of the invention provides a method of closing a container comprising applying a threaded closure to an opening of the container by 115 screwing on the closure againstthe container opening, mechanically limiting the closing head load to a value which is enough to ensure sealing of the container by means of a resilient sealing member of the closure, and relying on a stop formation separate 120 from the threading on the closure and/orthe containerto preventany substantial increasing ofthe head load during the life ofthe closed container.

In orderthatthe present invention may more readily be understood the following description is 125 given, merely by way of example, with reference to the accompanying drawings in which:-

Figure 7 is a diametral sectional view of a closure and container combination in accordance with the present invention;

130 Figure2\sa view similarto Figure 1 butshowinga

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second embodiment of the invention;

Figure3 is a view similarto Figure 1 but showing a third embodiment ofthe invention;

Figure4is a view, again similarto Figure 1, but 5 showing a fourth embodiment of the invention;

F/<7ure5isafurtherviewsimilarto Figure 1, but now showing a fifth embodiment of the present invention;

Figure 6\s a view, similarto Figure 1 but showing a 10 sixth embodiment ofthe present invention; and

Figure 7is a view which is similarto Figure 1 but shows a variation in the placement of the gasket.

Although forthe sake of illustration, the present invention will be described in terms of a glass jar and 15 plasticclosurecombination,itwillofcoursebeun-derstood thatthe principles of this invention can be applied to any type of containerfitted with a removable closure or lid, and to any form of closure or lid.

For example, in the specific embodiment about to 20 be described we referto a moulded plasticclosure having a gasket of softer consistency foreffecting sealing againstthe neck rim of a glass jar. The container may alternatively be a bottle, a drum, a tub, a canister, a can, or a pail; it may be formed of metal, 25 glass, or any one of a range of plastic materials; it may be formed with or without reduced diameter necks, the sealing member may comprise at least one integrallyformed sealing skirt such as is used in a so-called "linerless" closure, and the closure itself 30 may be of metal, glass or plastic, and may be of circular or non-circularconfiguration, as desired. One example of a container which can employ the pre-sentinvention isthatofa battery case.

In the embodiment shown in Figure1,thejar1 has 35 the closure 2 attached to it by a simple down-thrust to compress the resilient sealing gasket 3, and held in place by some detent means, not shown in the drawing.

On the exterior of the rim 4 of the jar is a rib 5 which 40 forms an abutment stop for the rim 6 of the skirt 7 of the closure 2.

The rib 5 may be continuous or discontinuous and may be of any suitable profile.

The positioning ofthe rib 5 relative to the rim 6 of 45 the closure skirt 7 is such that during vertical stacking of a plurality of jars ofthetype shown in Figure 1 the compressivestress imposed on the gasket material 3 by virtue of the weight ofthe filled jars above it in the stack is limited by abutment ofthe skirt rim 6 against 50 the rib 5 once a very small excess head load (down-thrust on the closure 2) is applied beyond the initial head load to close the jar. Indeed, it is even conceivable thatthe cooperation ofthe rib 5 with the rim 6 may serve to limit the closure-applying head load. 55 An alternative embodiment is shown in Figure 2 where the jar rim 11 now has the rib 15 positioned nearerthefree upper edge ofthe jar rim 14 and in any case above the rim 16 of the closure skirt 17.

The lower end ofthe skirt 17 is equipped with a 60 detent catch 18 which cooperates with the rib 15 to hold the closure 12 in place once an adequate head load has been applied to push the detent tooth 18 pasttherib15.

The head load-limiting stop is in this embodiment 65 defined partly bythe rib 15,which mayasinthe

Figure 1 embodiment be eithercontinuousordis-continuous and partly by a stop formation 19 on the radially inner surface ofthe closure skirt 17.

In this particular embodimentthe stop formation 19 is one of several axially extending ribs which thereby involve the use ofthe absolute minimum of additional material ofthe lid 12 but are nevertheless able to cooperate with the continuous or discontinuous peripheral rib 15 of the jar rim 11.

If desired, the stop formation 19 may comprise a zone of increased radial thickness ofthe skirt 17 running right around the skirt.

The cap 12 may be a lug cap, i.e. one having a plurality of equiangularly spaced inwardly extending lugs (beads of short peripheral extent) each engaging with one of a plurality of short threads 15 on the jar.

The Figure 3 embodiment shows an alternative form in which the external peripheral ribofthejaris replaced by an outer shoulder 25 which is engaged by an inner shoulder 29 ofthe closure skirt 27. In turn, the detent member 18 of Figure 2 is here replaced by a thread formation 28 which allows the closure 22 to be screwed on and unscrewed manually, but which nevertheless permits the closure to be applied by pure down-thrust under adequate head load, causing the threads 28 to ride over thethreads ofthe jar 24 by virtue of deformation ofthe closure skirt 27 and/orthe jar threads 24. As with the embodiments of Figures 1 and 2, the gasket 23 is compressed to a first given extent during the closing action and the additional strain to which it may be subjected during stacking is limited by cooperation ofthe shoulders 25 and 29 of the jar 21 and closure 22, respectively.

Figure 4 shows yet a further alternative embodiment in which the head load-limiting stop comprises a downwardly extending bead 39 embedded in the gasket 33 ofthe closure 32 and having a height such that in the event of a small increase in compressive strain of the gasket 33, for exam pie, due to vertical stacking offilled jars,the bead39 will abuttheupper end face ofthe rim 34 of the jar 31 to limitfurther compression of the gasket.

The closure 32 is held on the jar 31 by detent means, not shown.

Figure 5 shows a modified form ofthe embodiment of Figure 4 where the bead 49 is positioned nearerthe radially inner part of thefree end of the jar rim 44 so that the bead 49 forms a containment wall forthe gasket 43, thereby economising on the amount of plastic material used to form the gasket.

As in the embodiments of Figures 1 and 4, the lid 42 of Figure 5 is held in place by some form of detent means, not shown.

Whereas it is quite in orderforthe bead 39 of Figure 4 to be continuous or discontinuous, because the corresponding bead 49 of Figure 5 serves as a containment wall forthe gasket material it will in all probability be in theform of a continuous bead running around the closure 42.

Asixth embodiment is shown in Figure 6 where the gasket of Figures 1 to 5 has been replaced by a resilient sealing fin or rib 3 integrallyformed with the end panel 52 ofthe closure. The application of head

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load to the closure, during closing, deflects the narrow rim of the fin 53 upwardly and the elasticity of thefin tightens the seal ofthe fin against the rim of thejar51.

5 As with Figure 1, the mechanical head load-limiting stop comprises an outwardly projecting continuous or discontinuous bead 55 engaged by the rim 56 ofthe closure skirt 57.

Finally Figure 7 shows a variation ofthe embodi-1 o ment of Figure 1, where the gasket 63 is positioned so as to engage the radially inward part ofthe rim of the jar 61. As with Figure 1, the mechanical head load-limiting stop comprises engagement ofthe rim 66 ofthe skirt of closure 62 with the radially out-15 wardly projecting continuous or discontinuous rib 65.

Althoughthevariousembodiments illustrated in Figures 1 to 5 employ a stop system using elements comprising either the rim 6,56,66 ofthe skirt 7,57,67 20 (Figures 1,6 and 7) or a stop formation 19,29,39 and 49 (Figures 2 to 5) formed inside the closure, it is alternatively feasible forthe stop members to comprise some external formation on the skirt of the closure and engageable with an external feature of 25 the jar rim, if desired.

Where the container is of plastic material this may comprise polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyvinyl chloride, polycarbonate, polystyrene, poly-30 acrylate or any other suitable plastic material. The container may also be formed from laminations of plastic materials such as, for example polyethylene terephthalate and polyethylene vinyl alcohol orac-etate, or might be coated with a barrier coating such 35 as polyvinylidene chloride. In addition to being formed of laminations of several different layers the container may also be composed of a composite such as a helically wound cardboard container having a plastic liner.

40 Where the closure isformedof plastic material this may comprise polyethylene, polypropylene, ethylene-propylene copolymer, polyethylene terephthalate, polyvinyl chloride, polycarbonate, poly-acetal, polyamide, polystyrene orthermosetting 45 materials such as urea formaldehyde. The material ofthe closure may also contain fillers such as whiting, calcium carbonate, china clay or glass fibres. The closure may also have a composite structure containing laminationsto reduce permeability to 50 gases.

The sealing member may bean integral part ofthe closure and formed during the injection moulding process or it may be a separate gasketting material inserted into the cap during orafterthe moulding 55 process.Intheformercasetheintegralsealmaytake theform of one or more annular projecting ribs or fins which contact the rim ofthe container and deflect or compress underthe closing forces to provide a seal. If the sealing member is a separate gasketthis 60 may be pre-formed into the desired shape, such as a disc or annulus and then inserted into the closure; it may for example be a laminated disc or annulus. Alternatively it may be introduced into the closure in a molten form to give an annular or overall gasket, 65 either by lining into the closure to the desired configuration or by moulding to the desired configuration after introduction into the closure. In another process the gasketting material may be in theform of a plastisol which is lined into the closure and then 70 fluxed to a solid state for example as disclosed in GB-A-2051660. This may be carried out either with or without moulding during or afterfluxing. The gasketting material may also comprise a one ortwo component polyurethane. It may also comprise a 75 natural orsynthetic rubber latextogetherwith optionally resins, fillers and other additives known to the art. Examples of such gasketting materials are given in our British Applications Nos. 8505677 and 8507095.

80 The gasketting material may comprise any visco-elastic gasketting material such as:

a) Ethylene-vinyl acetate copolymers alone or in combination with other materials such as low molecular weight polyethylene, resins, waxes, plasticisers,

85 oils, pigments, anti-oxidants, colouring agents and slip agents.

b) Polyvinyl chloride or copolymers of vinyl chloride and vinyl acetate together with suitable plasticiers and other additives.

90 c) Thermoplastic elastomers, such as styrene-butadiene block copolymers, styrene-isoprene-styrene block copolymers or elastomers such as butyl rubber alone or in combination with polyethylene, such as low density polyethylene or linear 95 low density polyethylene. These thermoplastic elastomers may also be used in conjunction with oil,

such as white oil, plasticisers and resins to form the gasketting material.

d) Water-based compositions using natural or

100 "synthetic rubber latices which may be single component systems ortwo component reactive systems (as described in the above British Applications).

e) One ortwo component polyurethane systems.

f) Foamed or unfoamed polyethylene orfoamed 105 polystyrene.

All ofthe above compositions may contain:-fillers such as talc, calcium carbonate, kaolin, orwhiting; pigments such as titanium dioxide; colouring agents; slip agents; and anti-oxidants.

110 The gasket may if desired have a foamed cellular structure brought about by foaming due to the addition of a gas or a blowing agent and caused to foam during orafterformation ofthe gasket but before application of the closure onto the container. For ex-115 ample it may comprise foamed polyethylene or polystyrene. Thecellularstructu re can also beobtained by including hollow microballoons of glass or plastic such as polyvinylidene chloride. Plastic microspheres containing a low boiling liquid such as poly-120 acrylonitrile/polyvinylidene chloride containing iso-butane may also be used. When the gasketting material such as a plastisol is heated to flux itthe microspheres expand to give a cellular structure.

If desired, the gasket may be caused to adhere in 125 place in the closure by the action of heat, pressure, or adhesive. Furthermore, the top panel ofthe closure defining the closure may, for example, be corona discharge treated in order to enhance adhesion ofthe gasketto thattop panel. From the above it will of 130 course be appreciated thatthe illustrations ofthe

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container^jar)and of the closure <lid) in the drawing are" not limiting arid that ally other suitabl e fcfl-ffi'Of closureor Container; or indeed of the sealing ■ member, (in this illustrative case a gasket) may be 5 provided. " • -

It is important thatthe head loa'd-|{miting:stdp formation should engageio limit head lead only once the closing headload has beerrapplied. Thus while we have indicated above that the stop formation may 10 indeed comprise'the means of limiting the closure-applying head loadyltis ofcourse importanttlratthe stop should allow sufficient head loadforthe purposes of deforming the sealing membe'rtaachieve adequate sealing, andforthe purposes of allowing 15 engagement ofthe detent or other holding means such as the threads 28 in Figure 3.whichholdthe closure in place; ' •

; WhefeappFopriate,theclosureskirtmay beprov-• ided with a "tamper-evident" feature welI known in 20 the art,for.example a reduced diameter portion which may be formed mechanically or by heat shrinkage so as to engage over an external rib on a neck ofthe container, and to fracture when theclosure isfirst removed frorn the container, - • 25 • • -• ' - -- ' ' :

Claims

CLAIMS • ••

1. In combination a container and a closure, the closureincluding:-aresilient sealing memberto be

30 placed under stress upon application of the closure to the containerto provide a resilient sealingforce applied by the sealing member againstthe con- • tainer, and stop means for limiting axial movement oftheclosurerelativetothecontainerin asense 35- which mcrease&the stress on the sealirigmember, * the arrangement being such thatthe stopmeans al lows a required closing axia1 ly directed head toad tobeappliedtoclosethecldsUreontothecontainer, butsubsequently prevents excessive head load from 40 being applied to the sealing member. •

2. The combination according to Claim 1,

wherein thestop means-isformedon theclosure.

3. Thecombination according to claim 1 orclaim 2, wherein the stop means informed on thecon-

45 tainer. ■

4. The combination according to any oneof claims 1 to 3, wherein the sealing member comprises a sealing gasket of a material softerthan the material

; frtfm which theclosure isformed.-: - :x.; 50

5. Thecombination accofdi'ng to any one of ""' claims 1 to 3, wherein the sealing member i&integral with the rest ofthe closure. • ••-

6. Thecombination according to anyone of . claims 1 to 4, wherein the sealing gasket is a pre-

55 formed-discorannuluswhiehisinsertedinthe • closure.

7. The combination according to claim 6, whereinthe preformed discor annulus is of laminated^construction.- -

60 8. Thecombination according to claim 6, • < wherein the preformed diseor annulus isfoamed polyethylene orfoamed polystyrene.

9. ■ -The combination according to any one of claims 1 to 8, whereinthe container is formed as a 65 laminateof several different materials.

10. -The cdmbinationaccordingtoanyone of claims 1 to 8, wherein thecontainer is formed of • glass, metalor,plastic.

11. The combination according to any one of--70 claims 1 to 10, wherein the closure includes a larni-

: nate of'several different materials. " .

' T2. = Thecombinationaccording toany oneof claims 1 to 10, wherein the closureisformed of glass,

- metal or plastic. • : s -:

75 ' . 13. Thecombination according to any one of •claims 1 to T2vwherein.said stop means comprises therimofa skfrtofthe closure andan external con-■titiilidusfordisCjOntinuousrib on the container.

14v.. Thecombination according to any one of 80 -Glaims-lito 12, wherein said stop means comprises an internal formation on the closure and engaging an external bead on the container. "15. Thecombinationaccordingtoanyoneof clainis 1 to 12, wherein said stop means comprises 85' ariinternal bead on theclosure engaging with the free end of a closure-receiving rim ofthe container. •16. The combination according to Glaim 15; whferein the cap is a lug cap: • ■ >

■ 17. The combination according to claim 15, 90 wherein said internal bead ofthe closure is con-

- tinuous anddefines a containmentwallforthe ora gasket defining the sealing member. . ^

18, - The combination accordingto anyone of Claims 1 to 17, wherein the closure is held in place on 95 the container by a screwthread.

.19;". The combination according to any oneof .-claims 1 to 17, wherein the closure is held in place on the container by mearisofadetent member. • -•* 20. Thecombination according to any one of 100 claims 1 to 19, Wherein the containeris a jar, bottle, drum, tub, canister, can or pail. <

■ • 24 In combination a container and aclosure, substantially as hereinbefore described with reference to and as illustrated in any oneof theac-

105 companying drawings. _ ; • •

22.- A method of closing a containercomprising applying a closureto an opening ofthecontainer principally by means ofdownthrust ofthe closure againstthe containeropening, limiting the closing 110 head load to a value which is enough to ensure seal-ing of the container by means ofthe closure by detent engagement ofthe closure on the container opening, and relying onastopformationontheclosure and/orthe containerto preventany substantial in-115 creasing ofthe head load during the life of theclosed • container. • ■ • . ■.

- - 23," ;:AmethHd of closing a containercomprising ■ applyi ng athreaded closure to an opening ofthe container by screwing on the closure againstthe 120" container opening, mechanically limiting the closing head load to a value which is enoughtoensure sealing ofthe container by means of a resilient sealing - member ofthe closure, and relying onastopform--"" ationseparatefrom thethreadingon the closureand/ 125--orthecontainerto Fireventany substantial increasing ofthe head load during the life ofthe closed container,. •

24. A method of closing a container substantially as hereinbefore descri bed with reference to the ac-130 companying drawing. ■

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Amendments to the claims have been filed, and have thefollowing effect:-

(a) Claims 1-24 above have been deleted. 5 (b) Newclaimshavebeenfiledasfollows:-

drum, tub, canister, can or pail.

15. In combination a container and a closure, substantially as hereinbefore described with reference to and as illustrated in any one ofthe ac-70 companying drawings.

1. In combination a container and a closure, the closure including:-a resilient sealing gasket of a material softerthan the material from which the

10 closure isformed to be placed under stress upon application of the closure to the containerto provide a resilient sealing force applied by the sealing member againstthe end face ofthe rim ofthe container; and stop means, formed in the closure end

15 panel and co-operable with a part of the end face of the rim ofthe container, for limiting axial movement ofthe closure relative to the container in a sense which increases the stress on the sealing member, the arrangement being such thatthe stop means

20 allows a required closing axially directed head load to be applied to close the closure onto the container without disturbing the seal between the sealing member and the part ofthe end face other than the first mentioned part co-operating with the stop

25 member, but su bsequently prevents excessive head loadfrom being applied to the sealing member.

2. The combination according to claim 1,

wherein the sealing member is integral with the rest ofthe closure.

30 3. The combination according to either one of claims 1 and 2, wherein the sealing gasket is a preformed disc or annulus which is inserted in the closure.

4. The combination according to claim 3,

35 wherein the preformed disc or annulus is of laminated construction.

5. The combination according to claim 3,

wherein the preformed disc or annulus isfoamed polyethylene orfoamed polystyrene.

40 6. The combination according to any one of claims 1 to 5, wherein the container isformed as a laminate of several different materials.

7. The combination according to any one of claims 1 to 5, wherein the container is formed of

45 glass, metal or plastic.

8. Thecombination according to any one of claims 1 to 7, wherein the closure includes a laminate of several different materials.

9. The combination according to any one of

50 claims 1 to 7, wherein the closure is formed of glass, metal or plastic.

10. Thecombination according to any one of claims 1 to 9, wherein the cap is a lug cap.

11. The combination according to claim 10,

55 wherein said internal bead ofthe closure is continuous and defines a containment wall forthe or a gasket defining the sealing member.

12. The combination according to any one of claims 1 to 11, wherein the closure is held in place on

60 the container by a screwthread.

13. The combination according to any one of claims 1 to 11, wherein the closure is held in place on the container by means of a detent member.

14. The combination according to any one of

65 claims 1 to 13, wherein the container is a jar, bottle,

Printed for Her Majesty's Stationery Office by Croydon Printing Company (UK) Ltd, 6/87, D8991685.

Published by The Patent Office, 25 Southampton Buildings, London, WC2A1 AY, from which copies may be obtained.