AU627270B2 - Tamper-indicating plastic closure - Google Patents

Description

I

FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIF!ICATION S F Ref: 119919

(ORIGINAL)

FOR OFFICE USE: Class Int Class 00 o 0 0 0 0 Complete Specification Lodged: Accepted: Published: Priority: RelatEd Art: Name xd Address of Applicant: H-C Industries, Inc, 12D] East Elmore Street Crawfordsville Indiana 47933 UK~ITED STATES OF AMERICA 9000 0 0 OS JO 0< 0 90 0 0 9 0 0 0 9 0 0 009 04 0 0 4 Address for Service: Spritson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Strep-- Sydney, New South Wales, 2000, Australia Complete Specification fur the invention entitled: Tamper-Indicating Plastic Closure The following statement is a full description of this invention, including the best method of performing it known to me/Lis 5845/6 Si

ABSTRACT

A tamper-indicating plastic closure is disclosed, with the closure configured for interfering coaction with an associated container. The closure includes a plastic cap having a top wall portion and an internally threaded annular skirt portion, with an annular pilfer band depending therefrom. The pilfer band includes a plurality of circumferentially spaced flexible tabs configured for interfering engagement with an annular locking ring portion of the associated container. The pilfer band further includes an annular o6 interference bead positioned beneath the flexible tabs.

By this arrangement, two modes of interfering engagement oo with the associated container locking ring are provided.

04 0 0 o 015 In an alternate embodiment, the pilfer band includes an 0 00 angularly skewed interference lip and centering ribs.

0004 00o.

0 0 00 0 0 o o o0 o o

IA-

TAMPER-INDICATING PLASTIC CLOSURE Cross-Reference To Related Application This application is a continuation-in-part of U.S. patent application Serial No. 07/343,995, filed April 26, 1989.

Technical Field The present invention relates generally to tamper-indicating or tamper evident packaging arrangements, and more particularly to a tamperindicating plastic closure for a container which functions to provide two modes of interference with the o°°0 container for enhanced tamper resistance.

Background Of The Invention oooo* The provision of tamper-indicating or tampero 15 evident closures for containers is desirable for all 0 0 9 manner of consumer products, so that partial or complete 4o4 removal of the closure results in clearly discernable visible alteration thereof. Typically, closures of this nature include an upper cap portion, and a depending pilfer band arranged to interact and cooperate with the container to which the closure is applied. The pilfer 0 band is typically configured so as to fracture and/or separate from the closure cap attendant to closure o 0 removal, thereby providing clearly discernable evidence that the container has been partially or completely opened.

°a°o As will be appreciated, it is desirable for a tamper-indicating closure to be as resistant as possible to tampering or the like without visibly discernable evidence thereof. To this end, the present plastic closure has been particularly configured for economical and efficient manufacture for use on existing containers, with the closure being highly resistant to tampering, consistent and reliable in performance, and -2highly versatile for use with a wide variety of different containers.

DISCLOSURE OF THE INVENTION There is disclosed herein a tamper-indicating plastic closure f'or a container having an annular locking ring, said closure comprising: a plastic cap having a top wall portion, and an annular, depending cylindrical skirt portion; and an annular pilfer band depending from said skirt portioi. and at least partially detachably connected thereto by frangible rib means, said pilfer band including an annular band portion, a plurality of circumferentially spaced, Inwardly extending flexible tab means, and an annular Interference bead positioned beneath said flexible tab means and extending inwardly of the bottom edge of said annular band portion; said flexible tab means being engageable with said container locking ring: when said flexible tab means extend generally angularly upwardly and inwardly of said annular band portion for fracturing said frangible rib means, and when said flexible tab means extend generally angularly downwardly and inwardly of said annular band and are disposed between said annular locking ring and said Interference bead for fracturing said frangible rib means.

o a 0 00 0 0 600 0 3 3 There Is further disclosed herein a tamper-indicating plastic closure for a container having an annular locking ring, said closure comprising: a closure cap including a circular top wall portion and a depending, generally cylindrical skirt portion having an internal thread formation; an annular pilfer band depending from said cylindrical skirt portion; frangible rib means at least partially detachably connecting said pilfer band to said skirt portion, said frangible rib means comprising a plurality of spaced apart frangible ribs; said pilfer band including interference means on the inside surface of said pilfer band, said interference means being engageable with the locking ring of said container during removal of said closure therefrom for fracturing said frangible ribs, said pilfer band further including centering means engageable with the locking ring of said container during removal of said closure therefrom for maintaining said pilfer band in a circular configuration.

o S o 0 0 o 0 0 I 0 0A k 448a e iro -4 BRIEF DESCRIPTION OF THE DRAWINGS A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: FIGURE 1 is a side elevational view, in partial -ross-section, of a tamper-indicating plastic closure embodying the principles of the present invention applied to an associated container; FIGURE 2 is a cross-sectional view of the novel tamper-indicating closure; FIGURE 3 is a fragmentary, side-elevational view, in parti-al crosssection illustrating application of the novel closure to the associated container; FIGURE 4 is a view similar to FIGURE 3 illustrating the closure after application to the associated container, and in a position for providing a first mode of interfering engagement with the container; FIGURE 5 is a view similar to FIGURE 4, illustrating the closure in position for effecting a second mode of interfering engagement with the associated container; FIGURES 6a and 6b are views similar to FIGURE 5, further illustrating the second mode of interfering engagement of the closure with the associated container; o 0 o 0 u 00 0 0 0 0u oa 0 0 Q 0 o 9 99 0 9 L riir r ~_ir FIGURE 7 is a fragmentary, cross-sectional view of a further embodiment of the present tamper-indicating plastic closure; and FIGURE 8 is a view similar to FIGURE 7 illustrating another embodiment of the present tamper-indicating closure.

FIGURE 9 illustrates a further embodiment of a tamper-indicating closure; FIGURE 10 is a cross-sectional view of the closure illustrated in FIGURE 9; and FIGURE 11 is a fragmentary, cross-sectional view taken along lines 11-11 of FIGURE a 06 or o ,oe oo 0o, 00 00 i o a oo oo a o, oo 006 00 00 0 0 00 0o ii 6 o 0 0 000 0 0) 0 00) 00 0 0 00 00009 0 0000 0 0 Detailed Description While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the invention, and is not intended to limit the invention to the specific embodiment illustrated.

10 With reference first to FIGURE 1, therein is illustrated a plastic closure 10 embodying the principles of the present invention. Closure 10 can be made by various injection-molding or compression-molding techniques, and it can be formed in accordance with the 15 compression-molding techniques taught in U.S. Patent No.

4,497,765, which is incorporated herein by reference.

As illustrated, closure 10 includes an upper generally cup-shaped closure cap 12 including a circular top wall portion 14, and a depending, annular 20 cylindrical skirt portion 16. Skirt portion 16 preferably includes an internal thread formation 18 0 configured for threading engagement in cooperation with the threads T of an associated container C to which the closure is fitted. If desired, the plastic closure can 25 be provided with an associated sealing liner, such as 0 illustrated ii. the above-referenced patent.

The present closure further includes an annular pilfer band 20 depending from and at least partially detachably connected to skirt portion 16 of the closure cap. Pilfer band 20 preferably comprises a continuous annular band portion 22 arranged in substantial vertical alignment with skirt portion 16.

In the preferred embodiment, the pilfer band is at least partially detachably connected to the skirt portion by a plurality of circumferentially spaced frangible ribs 24 n y

I

000 *o 00 04 Go00 which extend betweent 7be inside surfaces of the skirt 1) 09

C

00 00* 0 00 0 0 00 0 000~ portion 16 and the band portion 22 of the pilfer band.

As shown, the pilfer band 20 is otherwise distinguished and separated from the skirt portion 16 by a circuzaferentially extending score line 26.

In accordance with the teachings of U.S.

Patent No. 4,418,828, incorporated herein by reference, score line 26 and frangible rib 24 together cooperate to provide the desired frangible connection between the 10 pilfer band 20 and tht closure cap 12. Specifically, the closure cap 12 and the pilfer band 20 are formed integrally with each othzr during molding, with the ribs 24 molded on the inside surfaces of the skirt portion aind pilfer band. Thereafter, Fscore line 26 is formed, preferably by nse of a scoring cutting blade, thereby distinguishing and separating the pilfer band 20 from the skirt portion 16, with the score line 26 extending partially into the ribs 24.

0 By this arrangement, the unscored, "iresidual"i 20 portions of the frangible ribs 24 collectively provide 0 the desired frangible ronnection between the pilfer band and the skirt portion. If desired, an integral connector portion can be p- ided between the pilfer band and the skirt portion (such as by leaving a portion 25 of the closure uncut by score line 26) whereby the C pilfer band remains connected to the skirt portion 16 after fracture of the ribs. In conjunction with such a connector portion, one or more fracturable areas can be provided in the pilfer band itself, whereby the pilfer band splits and fractures during closure removal from the associated container.

Referring now to the configuration of the pilfer band 20, the present closure has been specifically configured to provide a very high degree of ta&mper resistance, and in particular provides two 0 0 ~r 0 0 00 4*90 0 ~'o 4 004 94 0 9 8 distinct and separate modes of interfering interaction with the associated container. To this end, the pilfer band includes a plurality of circumferentially spaced, inwardly extending flexible tabs 28 which extend inwardly from the annular band portion 22 of the pilfer band. In a current embodiment, twelve evenly spaced tabs 28 are provided about the circumference of the pilfer band, with each tab having a width of about 0.240 inches, and a thickness of between about 0.012 inches and 0.020 inches. By this arrangement, the free end portions of adjacent ones of the tabs 28 are closely spaced (about 0.070 inch spacing) when the tabs extend horizontally inwardly. This horizontally inwardly 0* extending orientation of the tabs is indicated in ',15 phantom line, and represents the orientation in which the flexible tabs 28 are preferably molded.

As will be fuirther described, the flexible tab 2a cooperate with an annular locking ring portion L of container C for effecting fracture of frangible ribs o "20 24, thereby providing the desired tamper-indication. In o, a first mode of interference and failure, the free end portions of the flexible tabs are engageable with the o0o 0e locking ring L. In a second mode of failure, the flexible tabs are configured to cooperate with an annular interference bead 30 provided generally at the lower edge of annular band portion 22 of the pilfer band 20. To this end, the interference bead 30 is positioned beeath the flexible tabs 28, with the upper, inward edge portion of the interference bead positioned relative to the flexible tabs so that this edge portion is engaged by the tabs in the second failure mode. In the preferred form, the inside diameter of the interference bead is about equal to or slightly less than a inside diameter collectively defined by the -LI-Ur~~ 9 inside surfaces of the circumferentially spaced franaible ribs 24.

Referring now to FIGURE 3, the function of the present c~our ill be described. During application of the (losure 10 to the associated container, the flexible tabs 28 engage the container C and are moved upwardly generally to an upwardly extending, out-of-theway disposition as the pilfer band moves downwardly relative to the container threads T and the container locking ring L. To this end, the flexible tabs 28 are o0 o preferably provided with a thickness about equal to the radial dimension of the frangible ribs 24, or the tabs 0 4 28 are otherwise configured to collectively define an 1 inside diameter about equal to an inside diameter 15 collectively defined by the ribs 24.

When the closure is fully seated on the container, the flexible tabs 28 have moved past the container locking ring L, and thereafter, due to the resilient memory of the plastic, assume a generally anularly upwardly and inwardly extending disposition, o as illustrated in FIGURE 4. The flexible tabs 28 are now in position for the first mode of interfering S interaction and failure in cooperation with the container locking ring. Specifically, unscrewing upward movement of the closure 10 relative to the container urges the generally upwardly extending flexible tabs 28 0o"0 into and against the container locking ring L. This interfering engagement with the container locking ring acts to resist the upward unscrewlng movement of the closure, thereby stressing and fracturing the frangible ribs 24. Fracture of the ribs 24 results in clearly visibly discernable separation of the pilfer band from the skirt portion 16, thus providing a clear indication of opening of the container, L-,.j 10 0 0 0 0 0' In a current embodiment, each flexz' tab 28 is of a generally planar configuration, having a thickness dimensioned between abo.ut 0.012 Inches and 0.020 inches. However, as will be appreciated, each flexible tab 28 is preferably dimensioned and configured for sufficient thickness, in the direction from its free end to its base integral with the band portion 22, so as to exhibit suffioient resistance to collapse or deformation to thereby provide the desired interfering interaction with locking band L. To this end, each of 0 the tabs 28 may be of a non-planar configuration, such 1Z as being slightly curved when viiewed in cross-section perpendicular to the length of each tab, or similarly, of a generally angled or compound configuration when similarly viewed. As will be appreciated, such arranements can act to enhance the "0column strength" of each flexible tab for prcviding the desired interfering engagement with ).op~ing ring L.

In accordance with the present invention, the flexA' ble tabs 28 are configured for cooperation with interference bead 30 to provide a second and distinct 0 mode of interfering engagement with the container o locking ring L. In the event that the flexible tabs 211 are moved from their angularly upwardly and inwardly ,25 dispositionj (such as by th;authorized manipulation or thet like, which is desirably inhibited by the inwardly extending bead 30) the flexible tabs will assume an angularly downwardly and inu'ardly extending disposition, as illustrated in FIGURE~ 5. In this o'cientation of the tabs, the tabt are positioned for engagement with the container locking rlg L by disposition between the contr~iner locking ring and the upper inward edge of the interference bead 30. in this manner, the tabs cooperate and coact with the interference bead to again provide interfering interaction with the container 4 0 0 00 II 04 I I II A 11 locking ring, to thereby fracture frangible ribs 24 for at least partially detaching the pilfer band 20 from the skirt portion 16. This action is illustrated in FIGURES 6a and 6b, where in FIGURE 6a, a flexible tab 28 is illustrated between the locking ring L and the interference bead 30, with FIGURE 6b illustrating the subsequent failure of frangible rib 24 and separation along score line 36.

Referring now to FIGURE 7, therein is dif illustrated an alternate embodiment of the present tamper-indicating closure. In most respects, this S eimbodiment is the same as the previously described 3 embodiment, although it will be noted that the closure 0 Oa illustrated in FIGURE 7 shows the provision of a sealing o^S liner 15 adjacent to top wall portion 14, and a vent groove 17 traversing the internal thread formation IS, with the vent groove 17 extending into the cylindrical skirt portion 16 of the closure. The provision of one "o o or more vent grooves 17 facilitates venting of gas a o2p pressure, attendant to closure removal, when the present closure is used in connection with a container having carbonated contents or the like.

As in the previous embodiment, the closure includes a pilfer band 20 which is distinguished and at I o 5 least partially separated from the skirt portion 16 by a 4 circumferential score 26. Moreover, the pilfer band includes a plurality (twelve being presently preferred) of circumferentially spaced, inwardly extending flexible taL. 28, again configured to provide a dual mode of interference with the locking ring of an associated contaitir. To this end, an inwardly extending interference bead 30 is positioned beneath the flexible tabs 28, with the tabs 28 being engageable with the interference bead 30 in the second mode of interaction of the closure with an associated container.

12 In this embodiment, the frangible connection between the pilfer band 20 and th% skirt portion 16 is provided by a plurality of circumferentially spaced, frangible ribs 124 which extend between the inside surfaces of the skirt portion and tYhe pilfer band.

Significantly, at least some of the frangible ribs 124 extend on the inside surface of the band portion 22 of the pilfer band 20 between adjacent ones of the fiexible tabs 28. In the illustrated embodiment, each of the o~ ao0 illustrated frangible ribs 124 is so configured.

This configuration of the frangible ribs 124 desirably acts to center the pilfer band 20 on the o o associated container C with respect to the container o 04 locking ririg L. By virtue of this configuration of the O°T5 frangible ribs 124, a very limited amount of clearance 0440 is provided between the container locking ring L and the inwardly facing surfaces of the frangible ribs 124 when the closure 10 is fully seated on the associated 0wo"", container. This desirably acts to enhance tamper- 0oo"o0 resistance since the frangible ribs 124 thus act to prevent deformation of the pilfer band to an out-ofround configuration, thus substantially precluding removal of the pilfer band from the associated container without attendant fracture of the frangible ribs 124.

Like the fraz,,ible ribs 24 of the previous embodiment, ribs 124 are rendered fracturable by virtue of the score line 26 partially extending into at least some of the ribs.

In the embodiment of FIGURE an arrangement is provided to facilitate efficient and accurate formation of the score line 26. Specifically, this embodiment includes a circumferentially extending scoring bead 127 on the inside of the closure, with the scoring bead 127 preferably extending continuously along

~I

I-L-

LCL-L

i-vL- 13 the inside of the closure, and with circumferential score line 26 positioned beneath the scoring bead.

During scoring of the present closure, a scoring mandrel inserted into the closure is preferably employed, with a scoring knife or the like then applied tc the exterior surface of the closure. For high-speed manufacture, it is presently preferred that position of the scoring knife be referenced relative to the interiorly-positioned scoring mandrel.

Accordingly, it is desirable to have the closure remain in a substantially fixed position on the a o scoring mandrel, without excessive deformation or 00 deflection during scEring. Otherwise, inaccurate 0 04 0 0 scoring may result.

0000 o.0: 15 Thus, the scoring bead 127 is configured to securely engage and seat against the scoring mandrel, whereby highly efficient and accurate formation of the score line 26, with the desired degree of partial 00*0 cutting of the frangible ribi 124, is readily 0.0 ;0 accomplished.

AS in the previous embodiment, the flexible tabs 28 are preferably provided with a thickness about eqg.al to the radial dimension of frangible ribs 124.

This preferred dimensional relation permits the tabs 28 to desirably support the interior of the closure during 0i'" scoring (when the tabs 28 are flexed upwardly against the inside surface of the closure) in absence of the scoring bead 127.

Efficient and accurate scoring is further facilitated by the disposition of the frangible ribs 124 between adjacent ones of the tabs 128. By this arrangement, any possible overlap of one of the tabs 128 with an adjacent frangible rib (such as by deformation and elongation of a flexible tab attendant to ejection from its molding apparatus) is avoided. Additionally, 14 14 this extended configuration of the frangible ribs 124 permits the score line 26 to be positioned relatively close to the bottom edge of the pilfer band 20, which has been found to desirably enhance the tamperresistance of the present closure, since any unauthorized manipulation or other tampering is more likely to result in fracture of one or more of the frangible ribs 124.

A further feature of the embodiment of FIGURE o. 10 7 concerns the formation of each of the frangible ribs 124 with an upper portion 125 which extends on the inside surface of skirt portion 16 above scoring bead 0 127. This configuration of the frangible ribs has been found to desirably enhance the columnar strength of the coo? 15 overall closure, which facilitates high-speed ejection from the associated molding apparatus.

Referring now to FIGURE 8, therein is 0 0illustrated a further alternate embodiment of the 00*0' present closure. In most respects, this embodiment is o" 20 like that described above and illustrated in FIGURE 7, although the embodiment of Figure 8 does not include a scoring bead 127. The absence of the scoring bead, together with the extended configuration of frangible ribs 124 (with upper portions 125) can enhance the gas a 25 venting characteristics of the closure.

Two additional features of the embodiment of FIGURE 8 should be noted. First, this embodiment of the present tamper-indicating closure includes an arrangement for prestressing this frangible connection between the pilfer band 20 and t1he skirt portion 16 provided by the frangible ribs 124. Specifically, a plrality of circumferentially spaced, prestressing projections 131 are provided on the inside surface of the band portion 20 of the pilfer band. In the illustrated embodiment, and in accordance with the 15 preferred configuration, these prestressing projections 131 are each positioned on a respective one of the frangible ribs 124. In the illustrated embodiment, the prestressing projections 131 dre provided on alternate ones of the frangible ribs 124, but a fewer or greater number of the projections 131 can be similarly provided.

Projections 131 can be provided to prestress the frangible ribs 124 attendant to both application and removal of the closure. During application of the a* o closure to the associated container, the projections 131 are engageable with the container locking ring L, thus .Oo acting to expand and "bell out" the pilfer band S° attendant to application. This action can act to weaken 0 o the unscored, residual portion of each frangible rib 0o0 15 124, thereby facilitating failure of the frangible ribs in the intended manner during closure removal.

Additionally, the prestressing projections 131 can cooperate with the locking ring L during closure o'o removal. In particular, this can occur in conjunction 20 with stressing and fracture of the ribs 124 when tabs 28 extend angularly downwardly, and are positioned between o0 the container locking ring L and interference bead Attendant to this action, the projections 131 provide additional interference with the container locking ring, thus desirably subjecting the frangible ribs 124 to

I:

s o additional stress to assure fracture and failure of the ribs.

A further feature of the embodiment of FIGURE 8 concerns configuring the pilfer band 20 for fracture of the band portion 22, which is ordinarily desired, as discussed above, in conjinction with the provision of an unscored connector portion which integrally joins the pilfer band to the skirt portion 16 after fracture of ribs 124. By such an arrangement, the pilfer band 16 remains joined to, but partially detached from, the skirt portion 16.

To this end, FIGURE 8 illustrates the manner in which a vertical score is preferably formed in the pilfer band 20. Specifically, an external scoring knife is preferably applied to the pilfer band so as to form one or more scores extending to a depth as illustrated in phantom line at 133. Preferably, such vertical scoring is provided between one of the flexible tabs 28 o.1W and an adjacent frangible rib 124, so that such vertical oo4 scoring does not extend into either :te tab 28 or the So rib 124.

0o00oo o Notably, it is preferred that the vertical o oo scoring extend partially, but not completely, into the interference bead 30, to thereby define a fracturable residual portion 135 of the pilfer band. This arrangement preserves a desired degree of strength in the pilfer band, to facilitate high-speed application, oa while still rendering the pilfer band fracturable in the intended manner.

o Thus, a high degree of tamper-resistance is o provided by the present closure. As will be appreciated, various modifications and departures from the illustrated embodiment can be effected. For example, the umiber, spacing, thickness, and o c0 configuration of the flexible tabs 28 can be varied and Sselected while keeping with the principles disclosed herein. Similarly, while the annular interference bead is preferably substantially continuous in nature for providing additional circumferential hoop strength for the closure, segmented or otherwise discontinuous configurations for the interference bead can be alternately employed. Moreover, while the present invention has been illustrated in the form of a onepiece, all plastic closure, it will be appreciated that 17 a closure embodying the present invention may be composite in nature, such as a combination metallic and plastic closure (with or without a separate sealing liner).

Referring now to FIGURES 9-11, therein is illustrated a further embodiment of tamper-indicating plastic closure 10. In accordance with previous embodiments, this plastic closure 10 includes a cup-like closure cap 12 having a circular top wall portion 14, °ooofo0 and a depending annular or cylindrical skirt portion 16 .E.o having an internal thread formation 18. As shown in FIGURE 9, closure 10 is intended to be applied to an o associated container C having an external bead-like o locking ring L which extends circumferentially of the 15 neck portion of the container perpendicular to the vertical axis thereof. Locking ring L is positioned just beneath external container threads T, with the 0oo3 container C including a hand grip or handle H.

In this embodiment, the closure includes an on 0 annular pilfer band 20 depending from skirt portion 16 which is at least partially detachably connected to the Sskirt portion by a plurality of circumferentially spaced apart fracturable bridges 22. The fracturable bridges o can alternately be provided generally along the inner surfaces of the pilfer band and skirt portion, such as 0a 00 disclosed in U.S. Patent No. 4,418,828.

Pilfer band 20 includes an annular, bead-like interference lip 24 extending circumferentially about the inner surface of tie pilfer band 20. Notably, interference lip 24 does not extend porpendicularly to the vertical axis of closure 10, but rather extends in a plane arranged at an acute angle relative to the vertical axis of the closure. In the preferred form, this plane is arranged at an acute angle in the range of about 1 degree to about 5 degrees relative to the 18 closure axis. While the interference lip as shown is extending continuously about the inner surface of the pilfer band 20, it should be recognized that the lip 24 may be otherwise configured, so as to extend discontinually about the inner surface such as by the provision of a series of segments, lugs, or like projections. Whether the interference lip 24 is of a continuous or discontinuous configuration, it is contemplated that the lip extends in a skewed or non- 0°oC10 perpendicular relationship to the vertical axis of the V o' closure.

0o °o By virtue of the skewed configuration of the 00 interference lip 24 with respect to the closure axis, 0 00 oq non-circular engagement is created between the 15 interference lip and the locking ring L of the container during application and removal of the closure.

Consequently, stresses created on the closure, are nono0ooo uniform about the circumference of the closure.

During application, this non-uniform stressing desirably results in the deformation of the pilfer band o 20 to an out-of-round, non-circular configuration, i.e., to a generally elliptical or oval shape. This deformation in the pilfer band facilitates movement of .o0 the interference lip past the locking ring L during 0 25 application of the closure to the container, thereby o reducing the force required for application and minimizing stresses created on fracturable bridges 22.

During closure removal, the interference lip 24 again cooperated with th' container locking ring L to create a non-uniform stressing of the pilfer band 20, and in particular provide a progressive stressing of fracturable bridges 22. During closure removal, that portion of the interference lip 24 closest to the top wall portion 12 of the closure first engages the locking ring L of the container. This results in localized 19 stressing in the region of this initial engagement. In this manner, progressive failure of the bridges 22 can be induced.

In order to prevent the interference lip 24 from slipping over the locking ring L without failure of bridges 22 during closure removal, it is desirable to provide means for preventing the pilfer band 22 from assuming a non-circular configuration. To this end, a plurality of circumferentially spaced centering ribs 26 o 0 o~0 are provided on the inside surface of pilfer band above interference lip 24. Centering ribs 26 are 0 positioned to engage the container locking ring L during 6o1 O closure removal, and thus maintain the pilfer band in a 0o 0o circular configuration.

As will be appreciated, other suitable forms of centering means can be employed, such as by the provision of a continuous ring on the interior of the closure, or by the provision of an area of relatively o0 0 reduced inside diameter just above the interference lip.

2,0 In essence, it is contemplated that a centering arrangement be provided for engagement With locking ring j; L as the interference lip 24 engages the locking ring, to thereby prevent the pilfer band from assuming a noncircular configuration, thus assuring the intended °0 5 fracture of bridges 22.

S From the foregoing, it will be observed that niume 'ous modifications and variations can be effected without departing from the true spirit and scope of the novel concept of the present invention. It is to be understood that no limitation with respect to the specific embodiments is intended or should be inferred.

The disclosure is intended to cover by the appended claims al,1 such modifications as fall within the score of the claims.

Claims (13)

1. A tamper-indicating plastic closure for a container having an annular locking ring, said closure comprising: a plastic cap having a top wall portion, and an annular, depending cylindrical skirt portion; and an ann!lar pilfer bard depending from said skirt portion and at least partially detachably connected thereto by frangible rib means, said pilfer band including an annular band portion, a plurality of circumferentially spaced, inwardly extending flexible tab means, and an annular interference bead positioned beneath said flexible tab means and extending inwardly of the bottom edge of said annular band portion; said flexible tab means being engageable with said container locking ring: when said flexible tab means extend generally angularly upwardly and inwardly of said annular band portion for fracturing said frangibl rib means, and when said flexible tab means extend generally angularly downwardly and inwardly of said annular band and are disposed between said annular locking ring and said interference bead for fracturing said frangible rib means,

2. A tamper-indicating plastic closure in accordance with claim 1, wherein oa said frangible rib means comprises a plurality of frangible ribs o0o .0 extending between the inside surfaces of said skirt portion and said annular band pction of said pilfer band, said pilfer band I ing a ,distinguished and at least partially separated from said skirt portion by o Q 25 circumferential score means extending partially into said frangible ribs.

3. A tamper-indicating plastic closure in accordance with claim 2, wherein each of said flexible tab means has a thickness about equal to the a Sradial dimension of said frangible ribs. 30

4. A tamper-indicating plastic closure in accordance with claim 1, wherein aI each of said flexible tab means has a thickness dimension between about 0.012 inches and 0.020 inches.

A tamper-indicating plastic closure io accordance with claim 1, including centpeing means engageable with said container locking ring for centering said closure on said container. 21

6. A tamper-indicating plastic closure in accordance with claim 5, wherein said frangible rib means comprises a plurality of circumferentially spaced frangible ribs extending between the inside surfaces of said skirt portion and said annular band portion of said pilfer band, said ceitering means comprising portions of at least some of said frangible ribs extending between adjacent ones of sail flexible tab means.

7. A tamper-indicating plastic closure in accordance with claim 2, including scoring bead means extending circumferentially about the inside of said closure for supporting the interior of said closure during formation of said circumferential score means.

8, A tamper-indicating plastic closure in accordance with claim 2, including prestressing means for prestressing said frangible ribs comprising a plurality of circumferentially spaced prestressing project'ons on the inside of said pilfer band each positioned on a respective one of said frangible ribs, said prestressing projections being engageable with said container locking ring for prestressing said frangible ribs.

9. A tamper-indlcating plastic closure in accordance with claim 1, wherein said pilfer band Includes at least one vertical score means extending partially into said interference bead to define a fracturable residual portion of said pilfer band. 25

10. A tamper-indicating plastic closure for a container having an annular locking ring, said closure comprising: a closure cap Including a circular top wall portion and a S"depending, generally cylindrical skirt portion having an internal thread V formation; 0 a 30 an annular pilfer band depending from said cylindrical shirt portion; :0a frangible rib means at least partially detachably connecting said 0 a to a a°°a pilfer band to said skirt portion, said frangible rib means comprising a plurality of spaced apart frangible ribs; said pilfer band including in'erference means on the inside surface of said pilfer band, said interference means being engageable with the I 22 locking ring of said container during removal of said closure therefrom for fracturing said frangible ribs, said pilfer band further including centering means engageable with the locking ring of said container during removal of said closure therefrom for maintaining said pilfer band in a circular configuration.

11. A tamper-indicating plastic closure in accordance with claim 10, wherein said frangible ribs extend between the inside surfaces of said skirt portion and said pilfer band, said centering means comprising portions of said frangible ribs extending on the inside surface of said pilfer band.

12. A tamper-indicating plastic closure in accordance with claim 10, wherein interference means comprises an interference lip extending about the inner surface of said pilfer band beneath said centering means in a plane extending at an acute angle to the vertical axis of said closure,

13. A tamper-evident plastic closure substantially as hereinbefore described with reference to the accompanying drawings. DATED this THENTY-SECOND day of MAY 1992 H-C Industries, Inc. Patent Attorneys for the Applicant SPRUSON FERGUSON a 0 o o 0 a