A PLASTIC CLOSURE FOR A CONTAINER

Abstract: A novel plastic closure (10) is disclosed having a self-engaging locking pilfer band arrangement for engagement with a locking ring (26) on the neck (24) of the container (12) to which the closure (10) is applied. The pilfer band (34) includes a plurality of circumferentially spaced, inwardly extending relatively thin flexible wings or fingers (42) which move to an out-of-the-way position during application of the closure (10) to the container (12). When the closure (10) is in place on the container (12), the wings (42) are disposed such that they engage the surface of the locking ring (26) on the container neck (24) when the closure (10) is moved for removal from the container (12). During removal, each wing (42) engages the locking ring (26) so that resistance to removal of the closure (10) is created in the pilfer band (34), whereby areas of reduced strength fracture clearly indicating partial or complete removal of the closure (10) from the container (12).

Description: Technical field of the invention The present invention relates to a plastics closure for a container whereof the neck is formed with a screw-thread and a locking ring below the screw-thread, comprising a top wall, a cyclindrical skirt depending from said top wall and having on its radially inner surface a screw-thread for engagement with said screw-thread on the neck of the container, and a pilfer band attached to and depending from said skirt by a plurality of circumferentially-spaced frangible bridges, a circumferential line of weakening defining the boundary between the skirt and the pilfer band. Background of the Invention A wide variety of closures are known for closing and sealing bottles and other like containers. One type of closure is typically provided with internal threads on its side wall portion which are adapted to engage external threads on the neck of the container for retention of the closure on the container. Rotation of the closure with respect to the container results in the closure moving axially of the bottle neck so that the closure may be removed and the container opened. One desirable feature for closures of the above descript­ ions is a provision for indicating whether the container has been previously opened by removal of the closure therefrom. To this end, various arrangements for so-called pilfer bands are known. Frequently, a peripherally extending annular locking ring or other arrangement is provided on the neck of the container for interaction with the pilfer band of the closure for indication of closure tampering. For a closure made from plastic material, it is desirable that the pilfer band be formed integrally with the shell or cap portion of the closure. When the closure is applied to a container, the integral pilfer band portion of the closure is typically brought into association with the annular locking ring or other arrangement provided on the neck of the container so that the pilfer band operatively interacts therewith for indicating whether the closure has been removed from the container. Because the application of closures to containers is preferably performed on a high speed production line, it is desirable that application be possible with the fewest number of production steps. Heretofore, the pilfer band arrangement for some plastic closures has required one or more specific production processes for properly associat­ ing the pilfer band arrangement with the locking ring or other retaining means provided on the neck of the container. Thus, the development of an effective, self-engaging pilfer band for a plastic closure which would be suitable for application to bottles or other like containers without the use of specialized production equipment would significantly enhance the desirablity of plastic closures for use in a high speed bottling operation. Summary of the Invention In accordance with the present invention, the plastics closure as defined in the above mentioned first paragraph is characterized in that a plurality of ribs extend between the internal surfaces of the skirt and the pilfer band and in that a score line defines the boundary between the pilfer band and the skirt and extends circumferential­ ly past the ribs whereby the score line constitutes the line of weakening and said ribs constitute frangible bridges. Furthermore, a connector portion can be provided which operates to retain a connection between the skirt and the pilfer band after the frangible ribs are fractured and which is not traversed by said score line. Moreover, it can be provided an actual line of weakening extending across the pilfer band at one circumferential end of the connector portion. The invention relates also to a method of making a closure comprising moulding from a plastic material, said closure having a top wall, a cylindrical skirt which depends from said top wall and which has a screw-thread on its internal surface, a pilfer band depending from said skirt and connected thereto by a plurality of circumferentially-­ spaced frangible bridges, and a circumferential line of weakening defining the boundary between the skirt and the pilfer band, characterized by forming in the moulding of the closure a plurality of circumferentially-spaced ribs extending between the internal surfaces of the skirt and pilfer band and subsequently scoring a circumferential line between the skirt and the pilfer band from the radially outer side of the closure which score line extends circumferentially past the ribs whereby the score line constitutes the circumferential line of weakening and the ribs constitute the frangible bridges. In case that a connector portion is provided between the skirt and the pilfer band the score line can extend continuously from one circumferential end of the connector portion to the other without traversing the connector portion. As the closure is rotated for removal from the container, the above locking interaction of the pilfer band with the container neck resists the torque applied to the closure, and thus creates shear forces within the closure. When these shear forces reach a magnitude which is sufficiently great, the peripheral weakened skirt portion of the closure fractures, thus providing a clear indication that the closure has been removed, or partially removed, from the container. Brief Description of the Drawings FIGURE 1 is a cross-sectional elevational view of a plastic closure in accordance with the present invention applied to a bottle or like container; FIGURE 2 is a perspective view looking into the plastic closure of Figure 1; FIGURE 3 is a fragmentary perspective view taken along lines 3-3 of Figure 2; FIGURE 4 is a view taken along lines 4-4 of Figure 1; FIGURE 5 is a fragmentary view similar to Figure 4 illustrating the closure of Figure 1 during application to the container; FIGURE 6 is a view similar to Figure 5 illustrating the closure of Figure 1 during removal of the closure from the container; FIGURE 7 is a fragmentary perspective view further illustrating the closure of Figure 1; FIGURE 8 is a perspective view illustrating removal of the closure illustrated in Figure 1 from a container; FIGURE 9 is a cross-sectional elevational view of an further embodiment of a plastic closure in accordance with the present invention applied to a bottle or like container; and FIGURE 10 is a view taken along lines 10-10 of Figure 9. Detailed Description While the present invention is susceptible of embodiment in different forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment and an alternate 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 embodiments illustrated. With reference now to Figure 1, therein is illustrated a molded plastic closure 10 in accordance with the preferred embodiment of the present invention. Closure 10 is shown applied to a bottle or like container 12. Closure 10 may be fabricated from any of a variety of plastic materials, such as polypropylene or polyethylene. Closure 10 includes a cap 14 (sometimes referred to as a shell) which includes a generally circular top wall portion 16 and a generally cylindrical skirt portion 18 depending from and integral with top wall portion 16. Skirt portion 18 includes internal threads 20 which are adapted to mate with and engage external container neck threads 22 which are formed integrally with container neck 24. Container neck 24 includes a peripherally extending, continuous annular bead portion or locking ring 26 disposed beneath neck threads 22. Plastic closure 10 includes a plastic liner 28 positioned adjacent to top wall portion 16. Cap 14 includes an annular liner-retaining lip 30 which extends inwardly of the cap and aids in retention of plastic liner 28. As shown in Figure 1, plastic liner 28 is adapted to be brought into and maintained in sealing engagement with the side of the mouth of the container defined by the top of container neck 24. However, a closure in accordance with the present invention may be provided with a sealing arrangement other than side sealing liner 28 shown. Skirt portion 18 of cap 14 includes a plurality of circumferentially spaced, vertically extending external ribs 32 which facilitate gripping of closure 10. In accordance with the present invention, an integral pilfer band 34 is provided adjacent to skirt portion 18, as shown in Figures 1 and 2. Pilfer band 34 preferably is formed integrally with the closure 10 during its formation, and extends continuously about the closure and defines the lower edge thereof. Pilfer band 34 is distinguished from skirt portion 18 of cap 14 by a peripheral, fracturable weakened skirt portion. Preferably, this weakened skirt portion comprises a plurality of circumferentially spaced, integrally molded frangible bridges or ribs 37 which extend between the inside surfaces of pilfer band 34 and skirt portion 18. The fracturable skirt portion further comprises a score line 36 which extends peripherally of the closure for creating an area of reduced strength between pilfer band 34 and skirt portion 18. Score line 36 is preferably formed so that pilfer band 34 is substantially severed and detached from skirt portion 18 except for frangible ribs 37. Depending upon the desired strength of each rib 37, the cutting edge used to form score line 36 may also be used to simultaneously score or partially cut some or all of ribs 37. Ribs 37 provide an integral connection between pilfer band 34 and skirt portion 18 which is sufficiently strong to accommodate application of closure 10 to container 12 without failure. However, during rotation for removal of the closure from the container, pilfer band 34 resists the rotation and thus shear forces are created from the torque which act to cause ribs 37 to fail and fracture. Where score line 36 is provided substantially about the entire periphery of closure 10 and all of ribs 37 fracture, pilfer band 34 is effectively detachably connected to cap 14 of the closure, and thus fracturing of the weakened skirt area indicates partial or complete removal of the closure from container 12. Additionally, the detachable connection causes pilfer band 34 to be completely severed from cap 14 and to remain on container 12 after cap 14 is removed therefrom. As shown in Figure 2, pilfer band 34 may be provided with a vertical score 54 or other suitable area of reduced strength. The inclusion of vertical score 54 accommodates the severance of pilfer band 34 after it has been partially or completely detached from cap 14. Preferably, score 54 extends substantially through pilfer band 34. Since it is sometimes desirable to accommodate removal of pilfer band 34 from container 12 together with cap 14, a non-scored integral connector portion 56 defined by score line 36, preferably of relatively greater strength than one of ribs 37, joins pilfer band 34 and cap 14 so that pilfer band 34, is severable and removable from the container with the closure after the pilfer band separates or fractures along vertical score 54, as shown in Figure 8. Where removal of pilfer band 34 with cap 14 is desired, an integral connector portion may also be provided by having score line 36 extend substantially about the entire closure, with the depth of the score varied. In this way, a majority of ribs 37 may be simultaneously partially cut when score 36 is made, with one or more ribs 37 being non-scored so that they exhibit relatively greater strength then the other ribs 37 and do not fracture during removal of the closure, thus connecting pilfer band 34 to cap 14 for removal therewith from the container. While the above-described arrangement of ribs 37 and score line 36 provides the desired fracturable area distinguishing pilfer band 34 and skirt portion 18 and is presently preferred, other scoring arrangements could be provided. As best shown in Figure 3, pilfer band 34 includes a generally vertical, circumferentially extending annular band portion 38. Pilfer band 34 further includes an annular shoulder portion 40 which is integral with and extends inwardly of annular band portion 38. In order to provide for mechanically locking interaction between pilfer band 34 and container neck 24, pilfer band 34 includes a plurality of relatively thin, flexible, integral wings or fingers 42. Each wing 42 comprises a tongue-like projection preferably having a generally triangular configuration, the wings 42 being spaced circumferentially about the closure 10. It will be understood, however, that the exact configuration of each wing 42 is a matter of design choice in accordance with the principles disclosed herein, and could thus be other than generally triangular. While each of the wings 42 is generally triangular, they are not actually true triangles and include a plurality of distinct edge portions. An edge portion 44 of each wing 42 is integral with annular band portion 38 of the pilfer band. An edge portion 46 of each wing is integral with annular shoulder portion 40. Significantly, edge portion 44 is preferably disposed at an angle alpha with respect to the vertical and the rotational axis of closure 10 (See Figure 3). As will be further described, this angle is significant in that it accommodates application of closure 10 to container 12 without interference from wings 42. Additionally, angle alpha accommodates removal of closure 10 from the portion of the mold in which it is formed which forms the wings 42, relative rotation of this mold portion and the closure facilitating removal. Angle alpha is preferably in the range of approximately 20-60 degrees, with 30 degrees being shown in Figure 3. It will be appreciated, however, that angle alpha could be zero, i.e., wings 42 would be vertically oriented, for a closure in accordance with the principles herein as will be described. Each wing 42 further includes a first camming edge portion 48 which is adapted to engage and cam against the lower surface of locking ring 26 during removal of closure 10. Preferably, camming edge portion 48 is complemental to the lower surface of locking ring 26 which it is adapted to engage. The mechanical locking action of each wing 42 is further provided by a second locking free edge portion 50. Locking edge portion 50 defines the free end portion of wing 42 which is adapted to lockingly engage and interfere with the portion of container neck 24 disposed adjacent and below locking ring 26. Each wing 42 is further provided with an edge portion 52 extending between edge portion 50 and annular band portion 38. This edge portion 52 is preferably disposed at an angle from the horizontal, as shown, so that camming or flexing of the wings away from the container neck during application of the closure is facilitated. As indicated by angle beta in Figure 4, each wing 42 of the present embodiment preferably extends angularly inwardly of band portion 38 of pilfer band 34. Angle beta is shown measured between a line defined by the intersection of the generally planar surface of each wing and a horizontal plane, and a line tangent to the closure at the intersection of the first line with annular band portion 38. Angle beta is preferably approximately 75 degrees. As further discussed, the significance of this angular disposition is two-fold. First, during application of closure 10 to container 12, angle beta disposes each wing 42 so that it extends away from the direction of rotation during application, thus accommodating flexing of each wing 42 toward annular band portion 38 as the wings are moved by external threads 22 and locking ring 26. Further, this angle accommodates the dimensioning of wings 42 so that their length is sufficient to interengage and firmly abut and tend to lock against the portion of container neck 24 disposed adjacent and below locking ring 26. It should be noted that during fabrication of the closure in accordance with the present invention, removal of the plunger portion of the mold which forms threads 20 may deform the wings from the orientation in which they are molded. Since removal may result in this undesired deformation, particularly an increasing angle beta shown in Figure 4, it may be necessary to reorient the wings, such as by manipulation by a suitable implement moved across their surfaces. Experience has shown that the resilience or memory of the wings accommodates exertion of nominal pressure on the wings in order to correctly reorient them. Additionally, variation of the closure and mold temperatures affects the severity of the deformation, and they may thus be adjusted to minimize the problem. With particular reference to Figures 3, 4 and 5, the action of pilfer band 34 during application of closure 10 to container 12 will be described. Closure 10 is placed on container neck 24 and moved downwardly thereof. This operation is preferably performed by rotating closure 10 with respect to container 12 so that the internal threads 20 of skirt portion 18 engage and mesh with external threads 22 on container neck 24. As the closure is moved downwardly of the container, wings 42 of pilfer band 34 are moved into engagement with the upper surface of locking ring 26. Significantly, the angular disposition of each of wings 42 from the vertical (indicated by angle alpha) results in edge portion 52 of each wing 42 engaging the surface of locking ring 26 so that each wing 42 is flexed and urged outwardly of closure 10 away from container 12. This action is clearly illustrated in Figure 5 where each of wings 42 is shown flexed outwardly of closure 10, with their surfaces each engaging the outer surface of locking ring 26 (the arrow in Figure 5 indicates the direction of rotation of closure 10 with respect to container neck 24 during application in this fashion). Notably, annular shoulder portion 40 is preferably dimensioned such that it extends inwardly of annular band portion 38 a distance at least equal to the thickness of each wing 42. In this way, additional clearance is provided between band portion 38 and locking ring 26 so that wings 42 may flex to an out-of-the-way position as closure 10 is applied to container 12. As closure 10 is further applied to container 12 and liner 28 is brought into sealing engagement with the mouth of the container, each of wings 42 moves past locking ring 26 until each wing is disposed adjacent to and below the locking ring. After the wings have moved past the locking ring, they generally resume their original disposition due to their resilient nature or memory, and again extend at an angle from band portion 38. This condition is illustrated in Figures 1 and 4, in which camming edge portion 48 of each wing 42 is shown in engagement with the lower surface of locking ring 26. Significantly, in this embodiment of the present invention locking edge portion 50 of each wing 42 is disposed such that it engages the portion of container neck 24 disposed adjacent to and below locking ring 26. In this arrangement, internal threads 20 and external threads 22 firmly maintain closure 10 in position on container neck 24, facilitating sealing engagement of liner 28 with the mouth of the container. With particular reference to Figures 6 and 7, the action of wings 42 of pilfer band 34 during removal of closure 10 from container 12 will be described. The arrows in these figures indicate the direction of rotation of closure 10 with respect to container 12 during removal of the closure from the container. As closure 10 is rotated such as by manual torsion, the action of internal threads 20 and external threads 22 creates an axial force within closure 10 which acts in addition to the torque applied to the closure. As this axial force increases, camming edge portion 48 of each wing 42 is urged into engagment with the surface of locking ring 26. As this occurs, each wing 42 is subjected to forces which act to urge the wing to fold or bend generally along edge portion 44 integral with annular band portion 38, as shown by the phantom arrow in Figures 3 and 7. In other words, each wing 42 attempts to increase angle beta by "bending backwards" or collapsing as closure 10 is rotated and the wings are urged into engagement with locking ring 26. So that pilfer band 34 creates a resistance to the torque introduced by rotation of closure 10 for removal, it is necessary that each wing 42 resists bending backwards or collapsing as camming edge portion 48 is urged and cams against locking ring 26. This result is achieved by the dimensioning of wings 42. Specifically, the length of each wing 42 is such that each extends a distance from band portion 38 greater than the distance between the band portion and container neck 24. Thus, the free end portion of each wing, defined by locking edge portion 50, is urged into interfering, firmly abutting locking engagement or contact with the portion of container neck 24 disposed below and adjacent to locking ring 26. Additionally, each wing 42, although flexible, has sufficient resiliency and thickness to effectively prevent locking edge portion 50 from collapsing and "moving past" container neck 24 as the wings are urged about edge portion 44 by camming edge portion 42 engaging locking ring 26. Thus, a resistance to the torque of rotation of closure 10 is created in pilfer band 34 as wings 42 resist the camming interaction of the wings with locking ring 26, since the lack of clearance between the band portion 38 and locking ring 26 causes the wings to effectively interfere and mechanically lock with container neck 24 so as to prevent the wings from collapsing or bending backwards. As the resistance to the rotation of closure 10 increases, a point is reached where the resistance is greater than the torque carrying strength of the fracturable skirt portion including frangible ribs 37. When this occurs, ribs 37 between pilfer band 34 and cap 14 fracture or fail resulting in detachment of pilfer band 34 from cap 14. Thus, pilfer band 34 clearly indicates that removal of closure 10 has been attempted. As noted above, pilfer band 34 may be provided with an area of reduced strength such as vertical score 54. Connector portion 56 thus accommodates removal of pilfer band 34 from container 12 together with cap 14 by exerting a tensile force on pilfer band 34 causing it to sever at score 54 so that it is removed from container 12 together with the remainder of closure 10. This is clearly illustrated in Figure 8 where pilfer band 34 is shown "pig-tailed" and being removed from container 12 with cap 14, the cap and the pilfer band being joined by connector portion 56 after ribs 37 and band portion 38 at score 54 have fractured. Of fundamental importance with regard to the design of the present plastic closure is the relationship of the exact dimensions of wings 42 and the strength of the fracturable skirt portion. Specifically, it is necessary that the resistance to removal by pilfer band 34 created by wings 42 be greater than the force required to fracture the weakened portion of the closure. Otherwise, of course, pilfer band 34 would not perform its intended function since the wings would collapse or otherwise deform without the closure fracturing as intended. Naturally, the weakened skirt portion of the closure must be sufficiently strong so that it remains intact during application of the closure to the container. Additionally, the wings preferably exhibit sufficient flexibility to accommodate movement outwardly of the closure away from the container during application to the container, yet have sufficient resilience or memory to generally resume their original disposition after moving past the locking ring or other portion of the container neck with which they are designed to interact. Thus, if the force required for causing the ribs 37 to fail is relatively high, the number and resilience (a function of dimension and strength of material) of the wings 42 must be correspondingly increased. Conversely, if ribs 37 are provided such that a relatively small force is required for separating pilfer band 34 from the remainder of closure 10, the number of wings 42 and their individual stiffness may be decreased. Thus, the number of wings illustrated in the present embodiment (approximately 20) may be increased or decreased depending upon relative strength of the weakened skirt portion of the closure 10. In view of this, it is particularly desirable to reduce the number and thickness of wings 42 to the minimum required to provide sufficient resistance to rotation for removal of closure 10, since economy of materials is of importance in economically producing plastic closures in high volume. With reference now to Figures 9-10, a further embodiment of a plastic closure having a pilfer band arrangement in accordance with the present invention is illustrated. Plastic closure 60 is similar to plastic closure 10 illustrated in Figures 1-7, and is shown threaded to a container 12 with a threaded neck 24 and locking ring 26 as illustrated in Figure 1. Closure 60 includes a molded shell or cap 62 having a generally circular top wall portion 63 and a generally cylindrical skirt portion 64 depending integrally therefrom. Skirt portion 64 includes internal threads 66 which are adapted to mate and engage with container neck threads 22 on container neck 24 so that closure 60 is rotatable for application to and removal from container 12. While closure 60 has been illustrated as threaded to container 12, it will be appreciated that the subject embodiment of the present invention could be adapted for closures which are otherwise retained on a container. In order to effect sealing of the mouth of container 12, closure 60 is illustrated as including a typical plug seal portion 68 associated with top wall portion 63 of the closure. Typical plug seal arrangements provide for sealing engagement of the closure with a portion of the internal surface of the container neck, as distinguished from the sealing arrangement of closure 10 illustrated in Figure 1. Closure 60 includes external ribs 70 for facilitating gripping of the closure during application and removal. Closure 60 further includes an integral pilfer band 72 depending from skirt portion 64 and defining the lower edge portion of closure 60. Pilfer band 72 is distinguished from skirt portion 64 by a fracturable area of reduced strength. In this embodiment, the fracturable area is provided by a series of circumferentially spaced scores 74 which define spaced, frangible bridges therebetween. The bridges detachably join skirt portion 64 and pilfer band 72, and remain intact during application of the closure to container 12. Scores 74 may be suitably provided by mounting closure 60 on a mandrel or other support and bringing a circular knife into contact with the closure. Preferably, the scoring knife may include a plurality of slots in its cutting surface so that it is discontinuous, and thus forms a series of scores 74. So that spaced frangible bridges are properly formed, scores 74 preferably extend substantially through the closure wall. If it is desired to weaken the spaced bridges defined by scores 74 so that they fracture as intended, they may be partially scored or cut. Scores 74 provide closure 60 with a fracturable weakened skirt portion so that when pilfer band 72 resists rotation of closure 60 with respect to container12 for removal therefrom, the frangible bridges fracture thus detaching pilfer band 72 from skirt portion 64 and clearly indicating attempted opening of the container. All of the spaced bridges may be designed to fracture so that pilfer band 72 is completely detached from skirt portion 64 of closure 60 so that the pilfer band remains on container 12 after removal of cap 62. Alternatively, pilfer band 72 may include one or more vertical scores and one or more integral connectors of relatively greater strength than the spaced bridges for connecting pilfer band 72 with skirt portion 64 whereby pilfer band 72 may be removed from container 12 with cap 62. Pilfer band 72 includes an annular band portion 76 and an annular shoulder portion 78 extending inwardly of band portion 76. Pilfer band 72 further includes a plurality of wings or fingers 80, similar to wings 42 shown in Figure 3, circumferentially spaced and integrally extending from band portion 76 and shoulder portion 78 of pilfer band 72. Each wing 80 comprises a relatively thin, flexible, tongue-like projection extending integrally from the band portion 76, connected therewith along integral edge portion 82. Each wing 80 further includes a shoulder edge portion 84 joined to annular shoulder portion 78. In order to effect engagement of wings 80 with locking ring 26 on container neck 24, each wing includes an engagement edge portion 86, preferably complemental to the lower surface of locking ring 26 which it is adapted to engage. Edge portion 86 of each wing 80 is urged into engagement with locking ring 26 when closure 60 is rotated for removal from container 12. Wings 80 of pilfer band 72 include a free edge portion 88 which defines the free end portion of each wing. Wings 80 of the closure of the present embodiment are adapted to principally engage only the locking ring 26 of container neck 24, with engagement of the wings with other portions of the container neck being unnecessary. As shown, each wing 80 includes an edge portion 90 extending between edge portion 88 and integral edge portion 82. As noted, the configuration of the wings may be further varied. In this embodiment, each wing is illustrated as vertically disposed. This orientation would correspond to an angle alpha of zero with reference to the angular disposition of wings 42 in Figure 3. While the vertical disposition of wings 80 provides the desired interaction with the locking ring of the container neck during removal of the closure, wings 80 could be angularly disposed with respect to the axis of closure 60 and container 12. A further distinction between wings 80 and previously described wings 42 is that wings 80 are illustrated as extending radially inward of closure 60 toward container neck 24. In other words, the angle beta shown in Figure 4 for wings 42 would be approximately 90 degrees for wings 80, although wings 80 could be similarly angularly disposed as are wings 42. The application and removal of closure 60 to and from container 12 is similar to that of closure 10 described above. During application to the container, the flexible nature of each wing 80 accommodates flexing and movement of each wing toward band portion 76 as closure is rotatably applied to the container and displaced axially thereof. In this way, movement of wings 80 past threads 22 and locking ring 26 of container neck 24 is accommodated, with sufficient clearance provided between container neck and annular band portion 76 of pilfer band 72 to allow the wings to flex out of the way. After wings 80 have moved past and are disposed beneath locking ring 26 of container neck 24, plug seal portion 68 sealingly engages with the mouth of the container. When wings 80 are in this position, their resilience or memory results in them generally resuming the disposition they had before closure 26 was applied to container 12. Thus, each wing 80 extends generally radially inward of closure 60, with edge portion 86 of each wing adapted to engage the lower surface of locking ring 26. During removal of closure 60 from container 12, the function of pilfer band 72 is similar to the function of pilfer band 34 described above. As closure 60 is rotated for removal and thus displaced axially of container 12, each wing 80 is urged into engagement with the surface of locking ring 26. As this takes place, each wing 80 is urged to bend about its edge portion 82 integral with band portion 76. In this embodiment, the resilience of each wing 80 is sufficient to resist bending "backwards" (opposite the direction of bending during application) or collapsing, and each wing is urged into frictional engagement with the lower surface of locking ring 26. As closure 60 is further rotated and the forces generated at the interface of edge portion 86 of each wing 80 with locking ring 26 increase, the friction generated at this interface also increases and thus each wing 80 resists rotation with respect to the locking ring. In this way, pilfer band 72 resists rotation as closure 60 is rotated for removal from container 12, and thus generates shear forces in the frangible bridges connecting pilfer band 72 with skirt portion 74. When these shear forces are sufficiently high, the frangible bridges fracture, and thus pilfer band 72 is detached from cap 62, clearly indicating that closure 60 has been rotated for removal from container 12. Notably, this embodiment provides wings 80 of sufficient resiliency so that mechanical interference of the wings with a portion of the container neck disposed adjacent and below locking ring 26 is not necessary for providing the desired resistance to rotation of the closure. Where the materials of which the closure and container are fabricated do not exhibit sufficient friction to provide the desired resistance to rotation when wings 80 are urged against locking ring 26, the surface of locking ring 26 may be provided with a series of serrations or other surface irregularities for enhancing the frictional engage­ ment and contact between the wings 80 and locking ring 26. Such serrations or surface irregularities may be radially or otherwise angularly disposed such that they conform to the angular disposition of the wings corresponding to angle beta shown in Figure 4 to enhance engagement with the wings. From the foregoing, it will be appreciated that the function of a pilfer band relates to the relatively flexible nature of the pilfer band wings which permits them to flex laterally or outwardly of the closure during application, while they still exhibit sufficient resilience in a generally vertical direction to provide the desired interaction with the container neck. To this end, the wings illustrated have been described as dimensioned to provide these characteristics, with each wing having a generally uniform thickness and being relatively thin in a circumferential direction. However, the desired results may also be achieved by providing each wing with a portion of relatively reduced thickness at or near in integral connection with the band portion of the pilfer band. In this way, each wing is provided with a "hinge" to provide the desired flexibility which would not depend on the overall thickness of the wing. Thus, it will be appreciated that the exact configuration of the wings on a pilfer band may be widely varied, and that the configuration may be readily adapted for use on containers having neck portions of different designs. From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the true spirit and scope of the novel concept of the present invention. No limitation with respect to the specific embodiments illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications that fall within the scope of the claims.

Claims: 1. A plastics closure for a container whereof the neck is formed with a screw-thread and a locking ring below the screw-thread, comprising a top wall, a cylindrical skirt depending from said top wall and having on its radially inner surface a screw-thread for engagement with said screw-thread on the neck of the container, and a pilfer band attached to and depending from said skirt by a plurality of circumferentially-spaced frangible bridges, a circumferential line of weakening defining the boundary between the skirt and the pilfer band, characterised in that a plurality of ribs (37) extend between the internal surfaces of the skirt and the pilfer band and in that a score line (36) defines the boundary between the pilfer band (34) and the skirt (18) and extends circumferentially past the ribs (37) whereby the score line constitutes the ine of weakening and said ribs constitute the frangible bridges. 2. A plastics closure as claimed in claim 1, character­ ised by a connector portion (56) which operates to retain a connection between the skirt and the pilfer band after the frangible ribs are fractured and which is not traversed by said score line (36). 3. A plastics closure as claimed in claim 2, character­ ised in that an axial line of weakening (54) extends across the pilfer band at one circumferential end of the connecter portion. 4. A method of making a closure comprising moulding from a plastics material said closure having a top wall, a cylindrical skirt which depends from said top wall and which has a screw-thread on its internal surface, a pilfer band depending from said skirt and connected thereto by a plurality of circumferentially-spaced frangible ribs, and a circumferential line of weaken­ ing defining the boundary between the skirt and the pilfer band, characterised by forming in the moulding of the closure a plurality of circumferentially-spaced ribs (37) extending between the internal surfaces of the skirt (18) and pilfer band (34), and subsequently scoring a circumferential line (36) between the skirt and the pilfer band from the radially outer side of the closure which score line extends circumferentially past the ribs whereby the score line (36) constitutes the circumferential line of weakening and the ribs (37) are frangible. 5. A method as claimed in claim 4, wherein a connector portion (56) is provided between the skirt and the pilfer band, characterised in that the score line extends continuously from one circumferential end of the connector portion (56) to the other without traversing the connector portion.

Inventors: MCCANDLESS, THOMAS J., WILDE, SHELDON L.
Applicants: H-C INDUSTRIES, INC.
Application year: 1982
Main classification: B65D41
IPC codes: B65D41, B29C69, B29C37, B29C43, B29C53, B29C57