EP0544797B1

EP0544797B1 - Tamper indicating closure having retaining hoop with relief windows

Info

Publication number: EP0544797B1
Application number: EP91915918A
Authority: EP
Inventors: Thomas H. Hayes
Original assignee: Anchor Hocking Packaging Co
Current assignee: Anchor Hocking Packaging Co
Priority date: 1990-08-20
Filing date: 1991-07-31
Publication date: 1995-09-13
Anticipated expiration: 2011-07-31
Also published as: EP0544797A1; AU650056B2; DE69113051T2; EP0544797A4; AU8493991A; CA2089568C; DE69113051D1; MX9100740A; CA2089568A1; WO1992003348A1; ATE127756T1; JPH06504750A

Abstract

A closure (11) for a container (10) has a tamper indicating band (22) with a band retainer (29) in the form of an apertured flap or hoop which is hinged to the lower edge (30) of the band. A series of enclosed, open windows (36) or thin webs (36A) are formed in the retainer, extending toward but not to its distal edge (32). As the retainer is turned inside out from its as molded position to its use position, its distal and/or outer edges deform to relieve compression and permit the retainer to be inverted by direct downward pushing force. As a result of the deformation, the retainer in its use position may, depending on the number and relative size of windows or webs, have an advantageous polygonal peripheral shape rather than a circular shape.

Description

This invention relates to container closures of the type having a frangible tamper indicating band which, when broken, provides a visible indication that the container has been opened.
Closures having tamper indicating bands typically include some type of band retaining means which engages the underside of a locking bead around the neck of the container. When the closure is opened for the first time, the "retainer" exerts a downward force on the band which causes the band to sever and separate from the upper part of the closure. A visible gap is thereupon opened between the band and the upper part of the closure, which shows that the container and/or closure has been at least partially opened. The retainer is often in the form of spaced apart up-turned tabs or "fishhooks" around the inside of the band.
In order to assure that the tamper indicating band breaks in the initial opening, it is of course critical that the retainer positively engage the locking bead on the container and be arrested by it, rather than sliding upwardly past the bead as the closure is removed. For this reason a relatively stiff and unflexible retainer is desirable. If the retainer is too pliable or flexible, it may collapse or fold down when it comes into engagement with the locking bead and thus not resist upward movement of the band, and thereby permit the closure to be removed without visibly affecting the tamper indicating band. However, molding processes usually require that the retainer be molded in a "down" position, in which the retainer is angled inwardly and downwardly from the top. If the retainer, molded in the down position, is too stiff it resists being turned or folded from that initial "as molded" position, to its upturned, locking bead-engaging, use position.
In some instances, a closure can be applied to a container with the retainer in the down, as molded position; the retainer is automatically turned up or inverted to the use position as the closure is secured in place. In other cases, however, where the retainer is stiffer so as better to resist inadvertent downfolding on opening, a separate post-forming operation is used to turn it up after the closure has been molded but before the closure is applied to the container. Two factors are at cross purposes: the stiffer the retainer is, the more difficult it is to invert from the down, as made, position to the up, bead engaging, use position, but when in that position the more securely it will engage the locking bead when the closure is removed. If the retainer is so stiff that it must be turned up by applying point force progressively around its circumference at its inner edge, the application of the large force required usually slows the operation.
Thus there has been a need for a tamper-indicating closure having a retaining means which can be turned from a down, molded position, to an up, use position, at a rate consistent with high production speeds, but which is still stiff enough to insure that the band will break upon opening.
U.S. Patent 4506795 shows a tamper evident closure having a large number of individual tabs, each upwardly bent to engage the underside of a bead on the container. The tabs are separated from one another.
U.S. Patent 4592475 shows another closure having circumferentially spaced tabs.
U.S. Patent 4613052 shows a tamper indicating band which is generally cylindrical, connected to the lower end of a tamper indicating band by frangible bridges. The entire band is folded inwardly to a bead-engaging position by a separate post-forming operation, prior to application of the cap to the container.
U.S. Patent 4657153 shows a closure having a plurality of spaced, upturned locking tabs for engaging beneath the bead of a container. In Figure 7A of that Patent, hinges 13 at the base of tabs 10 are separated by intermediate slots 14. Each window is several times longer than the respective hinge.
U.S. Patent 4796770 shows a closure having a retaining means in the form of a plurality of hinged flaps which are separated circumferentially by notches to function independently.
In U.S. Patent 32879, an arrangement is described in which separately projecting stops are hinged along the lower edge of the tamper indicating band and are swung upwardly and inwardly to project into and through relief windows above the band which provide clearance for the stops to be cammed outwardly when the cap is applied.
U.S. patent No. 4,478,343 in Figure 10 shows a closure having a tamper indicating band with retaining tabs that are separated by thin webs between them. The webs extend inwardly nearly as far as the tabs. Gaps are presented between spaced apart hinged segments to make the hinge more flexible. In that closure the tabs are circumferentially flexible and, when swung through a horizontal center position, the inside dimension of the retainer is reduced by circumferential overlap along its inner edge.
WO-A-91/03405 (relevant under Article 54(3) EPC alone) describes a closure with a tamper band-retainer formed with an essentially continuous distal edge and windows in the retainer extending from the band lower edge towards but not to the distal edge. The retainer is invertible to a position in which it will engage the locking bead of a container, inversion causing deformation of the retainer portions which extend across or between the windows. The windows are open, i.e. they are apertures extending through the retainer.
A tamper indicating closure for use in sealing a container of the type having closure securing means and a locking bead below the securing means, the closure, in accordance with the invention, comprising a top, a skirt depending from the top, means on the skirt for engaging the closure securing means of the container, a tamper indicating band frangibly attached to and depending from the skirt, a retainer around a lower edge of the band for engaging the container below the locking bead thereof, a series of spaced integral hinges connecting the retainer to the band along the lower edge of the band, the retainer having an essentially continuous distal edge, and a plurality of relief windows in the retainer, the windows being webs which are substantially thinner than the retainer, the windows being between the hinges and commencing adjacent the lower edge, the windows extending toward but not to the distal edge, wherein the retainer is moveable between a first position in which it projects angularly inward in a direction away from the top, and a second position in which it projects angularly inward and toward the top, for engagement with the locking bead of the container, the retainer deforming along the distal edge above the windows or adjacent the lower edge of the band between the windows to relieve compression stress as the retainer is being moved from the first position to the second position.
If the retainer is in the form of a continuous, inwardly angulated unapertured conical hoop below the tamper indicating band, so-called "hoop strength" generally makes it difficult to turn the retainer inside out as is required to invert it from the down, as molded position, to the up, bead-engaging position. In accordance with this invention, the retainer is in the form of a flap or hoop which is essentially continuous around its distal (inner) edge. It is hinged along its outer edge to the band, and has a series of "relief windows" or internal deformation areas spaced along it. (As used herein in reference to the distal edge of the retainer, "essentially continuous" means that the retainer is unbroken or has only a single gap in its distal edge. A break such as a transverse gap in the distal edge makes it easier to press the retainer over the locking bead of a container, in comparison to the retainer of an otherwise similar closure having an unbroken edge. It is however far more difficult to remove a closure having no split or only a single split than a closure with a plurality of splits around its distal edge.)
The relief windows provide a balance between the force required to position the closure on the container, and the force required to provide the indication of tampering. They permit the hinged and/or distal edges of the retainer to deform in an advantageous manner, under the compression which arises during inversion. When the retainer is being folded to its up position, it deforms to relieve compression as it moves through a plane perpendicular to the closure center axis. The deformation may be in the plane of the retainer and away from the hinge line at the lower edge of the band; or it may appear as an arc which is perpendicular to the plane of the retainer; or the "mullions" between the windows may buckle adjacent the hinge line in a direction transverse to the plane of the retainer.
It has been found that, rather than providing openings through the hoop to relieve hoop strength, a similar result can be achieved by providing relatively thin webs rather than open windows. The webs must be thin enough that, like open windows, they also will relieve hoop strength. The webs, like open windows, are within (bounded by) the hoop and do not extend to the inner edge of the hoop. Like open windows, the provision of thin relief webs enables the hoop to be turned inside out much more easily, prior to the time the closure is secured to the container. The webs relieve the hoop strength as the hoop is turned from its down position, through an intermediate inturned center position in which its inside edge is in compression and its outside (hinge) edge is in tension, to its up position, so that the hoop can more readily be folded up for use, prior to seating on the container. It should be noted that, as used herein, the unmodified term "windows" is intended to mean and include both open windows and windows closed by a web so thin that it acts like an open window during inversion of the retainer.
The provision of a hoop with internal relief areas is preferable to spaced discontinuous band retaining means joined by webs, as taught by above-mentioned U.S. patent No. 4,478,343. That patent calls for tabs connected by thin webs; the inner edges of the webs are difficult to form consistently on a production basis. The retainer of this invention can be continuous around the closure, that is, without "gaps" along its inner edge. It can be relatively stiffer than such separate tabs, and indeed can be thicker at its inner (distal) edge than at its outer (hinge) edge, which is desirable to provide a tighter "grip" on the container.
Surprisingly, the windows afford a number of unexpected advantages. In comparison to a retainer without windows, they enable the retainer to be folded up more easily and quickly, prior to the time the closure is secured to the container. The windows more effectively relieve the compression stress as the retainer is up turned from the down position. The windows also provide a better balance between the force required to secure the closure on the container and the circumferential shearing force required to provide the indication of tampering, by increasing the shearing force. Preferably the windows have substantial "height" in comparison to the height (transverse dimension) of the retainer; optimally, they should extend at least 1/3 of the distance from the lower edge of the band (i.e., the hinge edge) to the distal (inner) edge of the retainer.
The retainer of this invention can be relatively stiff, and is preferably thicker at its inner (distal) edge than at its outer (hinge) edge. If the windows are narrow in relation to the circumferential dimension of the hinges between them, then the retainer (as viewed in plan in the use position) assumes a distinctly polygonal shape in which the portions inward of the hinges press more tightly against that container neck than the portions inward of the windows. This improves the "grip" of the retainer on the container and hence improves the band severing action when the closure is turned to open it.
A further advantage is that in use the entire inner edge of the retainer engages or lies very close to the container neck; preferably there are no significant gaps between the retainer edge and the container wall.
The windows closed by webs do not permit the entrance of an insect into the space between the band and the container, above the retainer. They make possible compliance with recommendations against any gap larger than 0.015" (0.4 mm) in the closure.

Description of the Drawings

The structure which provides these advantages can best be further described and understood by reference to the accompanying drawings, in which:

Figure 1 is a perspective view of the top part of a container having a closure in accordance with a preferred form of this invention;
Figure 2 (on a separate sheet from Figure 1) is an enlarged axial cross-section taken on line 2-2 of Figure 1;
Figure 2A is an enlarged sectional view similar to Figure 2 showing a closure in accordance with the invention having relief windows in the form of thin webs;
Figure 3 is an enlarged fragmentary perspective view of the tamper-indicating band and retainer of the closure of Figure 2, showing the retainer in its down, as-formed position;
Figure 4 is a bottom plan view of the closure showing the retainer in its as-formed position;
Figure 5 is a bottom plan view similar to Figure 4 but shows the retainer after it has been folded to its up or use position, for engaging the container locking bead;
Figure 6 is a fragmentary perspective view similar to Figure 3 but shows the deformation of the retainer after it has been folded to its use position;
Figure 7 is an enlarged fragmentary perspective view similar to Figure 3 but shows a closure having a retainer with more and larger windows,
Figure 7A is a view similar to Figure 7, but is of a closure in accordance with the invention having relief windows in the form of thin webs;
Figure 8 is a bottom plan view of the closure of Figure 7, with the retainer in its up position;
Figure 9 is a view similar to Figures 3 and 7 but shows a closure having a retainer with still larger windows, in accordance with another modified form of the retainer;
Figure 10 is a fragmentary perspective view of the closure of Figure 9, with the retainer in its up position;
Figure 11 is an enlarged fragmentary vertical section diagrammatically illustrating a retainer being inverted from the down to the up position; and
Figure 12 is a section similar to Figure 11 but shows the various ways in which the hoop may deform upon inversion.

Of the drawings, Figures 2A and 7A show a closure with a retainer having windows closed by thin webs according to the invention. The other drawings show closures with "open" windows as disclosed in European Patent Application 90914453.7.
In the drawings a container 10 is shown having a closure 11 applied to its top opening. For purposes of illustration closure 11 is shown as a one-piece plastic molding having an integral top 12 and skirt 14. However, it is contemplated that the principles of the invention are also useful with composite closures in which a metal or composite disk is inserted into an annular plastic shell. As used herein, the term "top" in reference to the closure includes both integral tops and separate tops; the shell or skirt 14 may be integral with or separate from the top.
The container 10 shown for purposes of illustration has closure securing means in the form of external threads 16 around its neck, which engage internal threads 18 on the inside of the closure 11. It should be appreciated, however, that the invention is useful not only on threaded containers but also on containers having interrupted canted lugs or a snap bead.
Around the lower edge 20 of closure skirt 14 there is attached a frangible or severable tamper-indicating band indicated generally by 22. This band 22 is in the form of an annulus and is formed integrally with closure skirt 14, to which it is connected by a series of spaced frangible bridges 25 (see Figure 3). The bridges 25 may be interruptions in a circumferential score line or partial cut 27 around the outside of the closure. The score line 27 severs band 22 from the remainder of the closure except at these bridges. Bridges 25 thus act as the "weak link" along which the tamper-indicating band 22 severs or tears from the upper part of the closure. (In the embodiment shown, the band 22 separates entirely from the rest of the closure when the bridges 25 rupture, and remains on the container thereafter. It is alternatively contemplated that band 22 may split along a rupture line as indicated by dotted line in Figure 7 and remain attached to the closure by a flexible connector after the bridges 25 have been broken, so that the band is removed with the closure rather than remaining on the container.)
As best shown in Figures 2 and 3, tamper-indicating band 20 includes a band retaining means or retainer 29 preferably in the form of a continuous hoop or flap connected integrally along the lower edge 30 of band 22. (The flap may have a "split," gap, or division as shown at 28 in Figure 4 in its inner or distal edge 32 at one point around its circumference, but this is not preferred.) Retainer 29 is molded in a first position in which it is angulated downwardly and inwardly from skirt 14 (see Fig. 3), i.e., away from top 12. As best shown in Figure 2, the retainer is preferably tapered so that it is thicker at its inner edge 32 than at its hinge edge 35, to provide greater stiffness.
Retainer 29 is hingedly connected to tamper-indicating band 22 by a series of spaced flexible integral hinges 34, each of which is preferably of sufficient angular extent to act as an arcuate joint when the retainer is folded about hinge edge 35, and thereby provide an over-center hinging action. The hinges 34 are separated or spaced from one another by relief windows or deformation areas 36, as shown in Figure 3. The windows 36 are preferably rectangular with outer edges which are colinear with the hinges 34 along edge 35. In the preferred embodiment shown, the windows 36 have a substantial height (dimension in the direction toward the distal edge): they extend at least 1/3 of the distance from the hinge edge to the distal edge, that is, the unapertured portion above the windows is less than 2/3 the height of the flap. However, in any case it is important that windows 36 do not extend to distal edge 32, that is, distal edge 32 is continuous and unbroken across both the windows 36 and the hinges, except possibly for a split as at 28. The windows 36 are open apertures but those shown at 36A in Figures 2A and 7A are thin webs. Preferably they begin at the hinge line 35 and extend toward distal edge 32. The closer the windows 36 extend to edge 32, i.e., the more nearly they sever the retainer, the less the hoop strength. If the windows 36 (open or webbed) are too large in a given closure and material, the retainer 29 may be so weak as to slide past a locking bead 40 and not sever the band at the score line 27. The webs must be membrane- or film-like in thickness, e.g. about 0.010-0.020" (0.25-0.5 mm), in comparison to the hoop which may for example be about 0.025-0.060" (0.6 mm-1.5 mm) thick. The webs are preferably coextensive with the upward face of hoop 29, as shown in Figure 2A, but could alternatively lie on the other (lower) face. In this embodiment the "mullions" 44 and hinges between the windows are wider, in circumferential extent, than the windows; depending on closure size, they may be substantially wider (e.g., about 1.5-6x) than the windows 36. In this embodiment the circumferential width of the windows 36 is preferably at least twice their height, depending upon the diameter of the cap 11. As shown in Figure 2, the distal edges of the windows may be angulated downward to facilitate stripping from the mold.
The closure shell can be molded; the webs are molded thinner than the retainer in which they are presented. As shown in Figures 2 and 2A, the inner edge of the windows 36 or webs 36A may slant downwardly to facilitate removal of the closure from the mold.
As already indicated, these windows 36 provide a surprising effect when the retainer 29 is inverted from its as-formed position (Fig. 3) to the use position shown in Figures 2 and 6, in which the inner edge 32 is positioned to hold beneath the locking band 40 of container 10. Because the retainer 29 is formed as a truncated cone with a circular distal edge 32, it might be thought that after folding to the use position of Figure 2, it would resume a circular configuration, the two positions being symmetrical about a plane through hinge line 35. However, that does not occur. On the contrary, in use position the retainer takes on a generally polygonal shape, as seen in plan in Figure 5. The polygonal shape is most pronounced in closures with relatively few and small windows.
More particularly, it has been found that the provision of the relief areas 36 permits the retainer to deform and thereby relieve the compression that arises along the distal edge 32 as the retainer is inverted from the down position to the up position. In the embodiment of Figure 2, the distal edge 32 deforms in the radial direction, forming arcs or peaks 42 extending outwardly (perpendicularly to the plane of the retainer) in the regions across the windows (between the hinges). When the retainer 29 has been folded to the up position of Figure 2, it surprisingly assumes the generally polygonal configuration shown in Figure 5, rather than a circular shape; the portions of the retainer between the hinges (i.e., across the windows 36) deform radially outwardly and thereby reduce the distance between the band and the retainer distal edge 32, with the hinge areas or mullions 44 between the windows 36 lying closer to the center axis of the closure. This shape enables the retainer 29 better to grip the container sidewall beneath locking band 40, regardless of manufacturing tolerances in the dimensions of the container 10 and the closure 11, and more certainly to shear the bridges 25 and cause the tamper-indicating band to separate.
Because the retainer 29 normally conforms relatively tightly to the container around its entire periphery, it acts as a seal against insect infestation. The fit can be so close that no opening between the distal edge 32 of the retainer and the container wall exceeds the maximum recommended limit of 0.015" (0.4 mm). The windows 36 themselves, if open areas, are partially closed by the deformation of the retainer 29, and the gap above them may itself be less than 0.015" (0.4 mm). The webbed windows 36A close altogether. Moreover, the distance from the line of contact of retainer distal edge 32 with the container, to the bottom 34 of the closure, may be 1/8" (0.3 cm) or less, in compliance with federal FSIS regulations. This avoids possible intake of dirt or contamination into the container when the vacuum is broken.
Apart from relieving hoop strength as the retainer is inverted to the use position, open apertures also facilitate water washing of the interthread space between the closure 11 and the container 10. For example, a water wash spray directed downwardly through water slots above it in the closure 11, and/or upwardly toward distal edge 32, can flow between the lugs or interrupted threads to wash them, then drain downwardly into the V-shaped pocket 48 carrying any entrained food particles and flow out through the windows 36.
In the embodiment shown in Figures 1-6 and described above, the windows 36 are relatively few and narrow in relation to the width of the hinge mullions 44 between them. As already noted, that embodiment provides a relatively stiff retainer. For some applications so much stiffness is not needed and the proportion of window area can be larger. This also reduces the area of the pockets 48 between the retainer and the band and provides a larger open area for better water washing and drainage. Two embodiments having progressively larger windows are shown respectively in Figures 7 and 8, and 9 and 10.
In the embodiment of Figures 7 and 8, the windows 36 are about equal in width (circumferential dimension) to the hinge mullions 44 between them. In this embodiment, as in the first, the areas above the windows 36 deform outwardly radially toward band 22, as indicated by arrow 45 in Figs. 6 and 12, but the deformation of each is less because there are more windows. In the up position, the retainer still forms a polygon but the peaks 42 are much less pronounced (see Fig. 8). They can for example be felt as non-uniformities by running a finger around the inner edge of the hoop 29 in the up position.
If the windows 36 are of still greater width and/or height, i.e., wider than the hinges, as in the embodiment of Figures 9 and 10, the retainer 29 still distorts along its inner edge, across the windows, to relieve compression stress, but in a different way. Here the distortion is in a different direction than the transverse distortion shown in Figures 6 and 8, and is in the plane of the original (underformed) band. In this embodiment the deformation is away from the hinge edge 35; as indicated by arrow 55 it is parallel to mullions 44, rather than radial, and distal edge 32 assumes a "wavy," undulating or up and down configuration (see Figure 10). In this embodiment the circumferentially narrow hinges may no longer function as arcuate hinges; they bend along essentially straight short lines, not arcs. This configuration is useful for small diameter closures; moreover, the wavy edge may interfit with corresponding ribs formed on the container finish to insure quicker band breakage upon turning. The windows should be open for this type of deformation to occur; webs would restrict it.
The various types of retainer deformation are further illustrated in Figures 11 and 12. In the down position, the inside diameter of the retainer, measured at its innermost edge, is designated by 50. In the up position (phantom line 52), it has approximately the same inside diameter 50. As the retainer 29 moves through the over-center (horizontal) position, half way between the down and up positions, its inside diameter wants to remain the same, but the retainer must deform for this to be possible thereby placing distal edge 32 in compression. Depending on relative window size and other factors, the distal edge will deform upwardly and inwardly in the plane of retainer 29 as at 54, or perpendicular to its plane, as at 42; or the hinge mullions can buckle from the plane, as at 58 in Figure 12. In each case the deformation is transverse to the original (undeformed) arcs of edges 32 and 35. The deformation occurs as the retainer crosses center but tends to remain after the retainer has reached the up position. In each case the accommodation of compression stress enables the retainer to be inverted from down to up by applying direct axial force simultaneously around the entire distal edge. The retainer need not be turned up by applying spot force progressively around the edge to "roll up" the retainer. This saves substantial time on a production line.

Claims

A tamper indicating closure (11) for use in sealing a container (10) of the type having closure securing means (16) and a locking bead (40) below the securing means (16), the closure (11) comprising a top (12), a skirt (14) depending from the top (12), means (18) on the skirt (14) for engaging the closure securing means (16) of the container (10), a tamper indicating band (22) frangibly attached to and depending from the skirt (14), a retainer (29) around a lower edge (30) of the band (22) for engaging the container (10) below the locking bead (40) thereof, a series of spaced integral hinges (34) connecting the retainer (29) to the band (22) along the lower edge (30) of the band (22), the retainer (29) having an essentially continuous distal edge (32), and a plurality of relief windows (36A) in the retainer (29), the windows being webs (36A) which are substantially thinner than the retainer (29), the windows (36A) being between the hinges (34) and commencing adjacent the lower edge (30), the windows (36A) extending toward but not to the distal edge (32), wherein the retainer (29) is moveable between a first position in which it projects angularly inward in a direction away from the top (12), and a second position in which it projects angularly inward and toward the top (12), for engagement with the locking bead (40) of the container (10), the retainer (29) deforming along the distal edge (32) above the windows (36A) or adjacent the lower edge (30) of the band (22) between the windows (36A) to relieve compression stress as the retainer (29) is being moved from the first position to the second position.
A closure as claimed in Claim 1, wherein portions of the retainer (29) which extend across the respective windows (36A) are deformed, when the retainer (29) is in said second position, in a direction radially outward from the retainer (29), toward the band (22).
A closure as claimed in either Claim 1 or Claim 2, wherein the retainer (29) in the first position is in the form of a truncated conical hoop having a circular distal edge, and in the second position has a distal edge (32) of polygonal shape wherein portions of the edge (32) which are between the windows (36A) lie radially inward of portions thereof which are across the windows (36A).
A closure as claimed in Claim 3, wherein the distal edge (32) is set by the deformation when the retainer (29) is moved from the first position to the second position.
A closure as claimed in any preceding Claim, wherein the circumferential dimension of the hinges (34) is greater than the circumferential dimension of the windows (36A), being preferably 1.5-6 times that of the windows (36A).
A closure as claimed in any preceding Claim, wherein the hinges (34) fold along arcuate lines.
A closure as claimed in Claim 1, wherein portions of the retainer (29) which extend across the respective windows (36A) are deformed, when the retainer (29) is in the second position, upwardly away from the lower edge (30) of the band (22), the deformation appearing as undulations in a direction parallel to the plane of the retainer (29).
A closure as claimed in Claim 1, wherein the retainer (29) is deformed, when the retainer (29) is deformed, in the second position, by buckling of portions (54) thereof between the windows (36A) and adjacent the hinges (34).
A closure as claimed in either Claim 7 or Claim 8, wherein the circumferential dimension of the hinges (34) is less than the circumferential dimension of the windows (36A).
A closure as claimed in any one of Claims 7 to 9, wherein the hinges (34) fold along straight lines.
A closure as claimed in any preceding Claim, wherein the windows (36A) extend at least ¹/₃ the distance between the lower edge (30) and the distal edge (32).
A closure as claimed in any preceding Claim, wherein the windows (36A) have outer edges which are co-linear with the hinges (34).
A closure as claimed in any preceding Claim, wherein the closure (11) is moulded with the retainer (29) in the first position.
A closure as claimed in any preceding Claim, wherein the retainer distal edge (32) is continuous around the entire circumference thereof or has a single gap (28) therealong.