Container closure assembly

An assembly includes a container and a closure. The closure includes a tamper-indicating band having a plurality of sloping teeth. Each of the sloping teeth of the tamper-indicating band has an engagement surface that is engageable with one of the engagement surfaces of the sloping teeth of the container. The sloping teeth on the tamper-indicating band are configured such that when one of the teeth on the tamper-indicating band completely engages one of the teeth on the exterior surface of the neck of the container, the engagement surface of at least one of the other sloping teeth on the tamper-indicating band is free from engagement with the engagement surfaces of the sloping teeth of the container and the engagement surface of at least one of the other sloping teeth of the container is free from engagement with the engagement surfaces of the sloping teeth on the tamper-indicating band.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention provides an easy to open container/closure assembly, more particularly, an easy to open closure/container assembly having a tamper-indicating feature.

2. Discussion of the Art

Two main types of bottle/closure systems that utilize breakaway bands for indicating tampering are currently commercially available. Both types have certain drawbacks. The first type locks the tamper-indicating band in place. This locking mechanism requires simultaneous application of two of forces: (1) the force to overcome thread and sealing surface friction to remove the cap and (2) the force to break the tamper resistance band, thereby resulting in high removal torques and high standard deviations of removal torque. The lowest removal torque that can be achieved with this system is approximately 18 inch pounds on average. This force is too high for elderly users and users suffering from arthritis. The second type involves the separation of the opening force from the force required to remove the tamper-indicating band, by allowing approximately 180° of free rotation of the cap before breakage of the tamper band is initiated. Accordingly, the closure is subject to substantial “back-off” (i.e. loosening) and possible leakage during distribution. This type of closure also does not provide any audible feedback in the area between cap opening and band breakage to reassure the consumer of safety. In both of these types of tamper resistance mechanisms, the force that breaks away the tamper resistant band is angular or circumferential and is applied by the torque of removing the closure.

U.S. Pat. No. 4,991,731 describes problems encountered when packaging consumable products in sealed containers. These problems are described below.

Due to concerns about material cost, container weight, and breakage, suppliers of consumable products desire to manufacture the container from a plastic substance, such as polypropylene, which is relatively inexpensive and may be colored or translucent. A problem arises when attempting to provide a cap for a plastic container, wherein the cap maintains a hermetic seal. Because it is difficult to maintain a hermetic seal in a plastic container, and conventional metal caps and plastic containers expand by a dissimilar amount, metal caps, by themselves, do not maintain a hermetic seals consistently on plastic containers when subjected to retort conditions.

During thermal treatment such as retort conditions, heat causes polymer relaxation or shrinkage, especially in the upper neck portion of the container. Injection or extrusion molded plastic bottles are formed by melting and pressure forming, which create stress and memory in the molecules of the polymer. The introduction of heat during the retort process causes those molecules to relax, so as to actually shrink the diameter of the neck portion of the container. This shrinkage causes severe problems in maintaining a conventional metal cap on a plastic bottle. This shrinkage may also prevent the use of a conventional plastic cap with a plastic bottle.

The problems mentioned above can be overcome by applying a substantial amount of torque when initially capping the bottle. However, the amount of torque necessary to maintain a conventional cap on a plastic bottle is so high that a person would not be able to easily twist the cap off the bottle following retort. Other alternatives would be to use an extremely expensive plastic to fabricate the bottle so that the plastic would not shrink at retort temperatures and could maintain an internal vacuum without distortion.

Screw on bottle caps have a tendency to loosen from a tightened condition on a threaded bottle neck finish. This tendency to loosen is often referred to as “back off”. This tendency to loosen has a number of causes, including, for example, temperature change, creep in the bottle and cap materials, relaxation of a liner or sealant material, and vibration during handling and shipping. This problem is more frequently encountered when the screw threads have a high pitch to enable the cap to be quickly removed and reinstalled with limited twisting action. Loose caps create problems for the manufacturer and retailer of packaged goods and even for the ultimate user. Loose caps can falsely indicate tampering, and, of course, allow spillage or leakage of the contents as well as entrance of contaminants into the container. A good moisture seal is especially important, for example, when pharmaceuticals and dietary supplements can be adversely affected by excess increases of or by excess decreases of moisture content. While “anti-back off” features are known in the industry, these features have not generally been available for bottles intended for use by elderly persons having limited strength and by sufferers from arthritis.

U.S. Pat. No. 6,296,130, EP 0 864 504 A1, WO 01/15988 A1, U.S. Patent Application Publication 2003/0160020 A1, and U.S. Pat. No. 4,349,116 disclose closure/container assemblies having “anti-back off” features. It is apparent that there is a need for an improved container/closure assembly that provides system seal integrity during retort, as well as permitting the sanitary opening of the container in a single action motion with a very low removal torque.

U.S. Pat. No. 4,813,561 describes containers and closures having tamper resistance bands. This patent describes ratchet teeth on a closure and sets of corresponding teeth on the container that engage below a retaining ledge. The sets of teeth on the container create gaps or spaces into which the tamper band can deform upon opening. However, due to the exact correspondence and alignment of the ratchet teeth on the container and closure, significant torque is still needed to break the tamper band bridges and remove the closure.

SUMMARY OF THE INVENTION

This invention provides a closure that addresses the aforedescribed disadvantages of container/closure systems that are currently commercially available. In one embodiment of the invention, and assembly comprises a container and a closure, wherein

said container has a neck, said neck having an interior surface, an exterior surface substantially curved about an axis, said interior and exterior surfaces joining at an opening of said neck, said exterior surface having (a) at least one thread, (b) a plurality of sloping teeth directed radially outwardly, and (c) a retaining bead positioned axially between said threads and said teeth; and

said closure has (a) a top wall; (b) a side wall defining an interior surface substantially curved about an axis, an exterior surface, an upper portion, and a lower portion; (c) at least one thread on the interior surface of said side wall adapted to mate with said thread on the neck of said container; (d) a tamper-indicating band having an interior surface, an exterior surface, an upper edge, and a lower edge, the upper edge of said tamper indicating band attached to the lower portion of said closure side wall by a plurality of rupturable bridges; and said tamper-indicating band further having a plurality of sloping teeth directed radially inwardly toward the sloping teeth on the neck of the container; wherein at least one tooth on the tamper indicating band engages at least one tooth on the exterior surface of the neck of the container, and wherein subsequent teeth on the tamper indicating band are angularly offset with respect to the teeth on the exterior surface of the neck of the container.

In one embodiment, the sloping teeth on the tamper-indicating band are formed on a radially outwardly facing exterior surface of a plurality of tabs depending downwardly from the lower edge of the tamper indicating band, said tabs being connected to said lower edge by means of a hinge such that the sloping teeth on outwardly facing exterior surface of the tab can be folded into a radially inwardly facing position. A side wall of these teeth, once folded inwardly, provide an upward-facing surface that engages the retaining band upon removal of the closure, in order to resist upward motion of the upper portion of the closure as it is torqued off the neck of the container. As the closure lifts off, the tamper indicating band—by interference fit of the teeth against the retaining bead, not by full engagement of the sloping teeth—is axially restrained from moving upward with the rest of the closure. This applies a stretching force on the rupturable bridges and eventually breaks them, leaving the tamper indicating band retained around the neck of the container. The interference fit of the side wall surface of the teeth with the underside of the retaining bead is preferably facilitated if at least one of the retaining bead or the upward facing side wall surface are continuous around the circumference: the retaining bead may be annular and continuous against separated teeth, or the side wall of the teeth—joined by connectors if teeth are formed on separate downwardly depending tabs—may form a continuous surface against a discontinuous retaining bead.

It may be preferable to form the sloping teeth of the closure on the exterior surface of downwardly depending tabs that are folded inwardly against the interior of the tamper indicating band, such that the sloping teeth now face radially inwardly, i.e. toward the axis of the closure. Alternatively, the teeth may be molded into the interior surface of the tamper indicating band, or formed on a separate ring that is fastened to the interior of the tamper indicating band. The teeth of the closure face the opposite direction as the teeth of the container, such that the tooth faces engage.

Methods are also described for providing the components of the assembly, and for using the assembly. For example, a method for a providing container-closure assembly, comprises

providing a container having a neck, said neck having an interior surface, an exterior surface substantially curved about an axis, said interior and exterior surfaces joining at an opening of said neck, said exterior surface having (a) at least one thread, (b) a plurality of sloping teeth directed radially outwardly, and (c) a retaining bead positioned axially between said threads and said teeth; for use with

a closure having (a) a top wall; (b) a side wall defining an interior surface substantially curved about an axis, an exterior surface, an upper portion, and a lower portion; (c) at least one thread on the interior surface of said side wall adapted to mate with said thread on the neck of said container; (d) a tamper-indicating band having an interior surface, an exterior surface, an upper edge, and a lower edge, the upper edge of said tamper indicating band attached to the lower portion of said closure side wall by a plurality of rupturable bridges; and said tamper-indicating band further having a plurality of sloping teeth directed radially inwardly toward the sloping teeth on the neck of the container;

wherein the providing step includes a step of ensuring that at least one tooth on the tamper indicating band engages at least one tooth on the exterior surface of the neck of the container, and that teeth are placed on the container such that subsequent teeth on the neck of the container are angularly offset with respect to the teeth on the tamper indicating band.

Further details of the container or closure as describe herein may be used in this method.

An alternative method for providing container-closure assembly, comprises:

providing, for use with a container having a neck, said neck having an interior surface, an exterior surface substantially curved about an axis, said interior and exterior surfaces joining at an opening of said neck, said exterior surface having (a) at least one thread, (b) a plurality of sloping teeth directed radially outwardly, and (c) a retaining bead positioned axially between said threads and said teeth,

a closure having (a) a top wall; (b) a side wall defining an interior surface substantially curved about an axis, an exterior surface, an upper portion, and a lower portion; (c) at least one thread on the interior surface of said side wall adapted to mate with said thread on the neck of said container; (d) a tamper-indicating band having an interior surface, an exterior surface, an upper edge, and a lower edge, the upper edge of said tamper indicating band attached to the lower portion of said closure side wall by a plurality of rupturable bridges; and said tamper-indicating band further having a plurality of sloping teeth directed radially inwardly toward the sloping teeth on the neck of the container;

wherein the providing step includes a step of ensuring that at least one tooth on the tamper indicating band engages at least one tooth on the exterior surface of the neck of the container, and that subsequent teeth on the tamper indicating band are angularly offset with respect to the teeth on the exterior surface of the neck of the container.

In use, as the closure is being removed from the container, the closure/container assembly described herein can provide the advantage of removal torques between approximately 3 and 16 inch pounds on average, thereby enabling elderly users and arthritic users to open the container with ease, without loss of back-off protection. Further, the partially engaged teeth provide a slight drag, i.e., resistance to rotation of the cap, and audible feedback to the user when the closure is rotated to open the container.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

As used herein term “side wall” means that portion of a closure depending from the top wall of the closure. The term “side wall” is synonymous with the term “skirt.” As used herein, the expression “top wall” means a panel that covers the opening of the closure that is positioned distally from the neck of the container. The expression “top wall” is synonymous with the expressions “end wall”, “cover”, “end panel”, “upper portion”. In one embodiment the closure is formed of a unitary component and the top wall is joined integrally with the side wall. In another embodiment, known as a composite closure, the top wall is distinct from the side walls, but is captured by and sealingly engages the side walls as described herein. As used herein, the expression “axis of the side wall” means a straight line about which the side wall is designed to rotate. The term “thread(s)” is intended to mean one or more screw threads.

As used herein, the term “tooth” means a projecting part resembling a tooth, as on a saw. The expressions “sloping tooth”, “tooth”, “ratchet” and “ratchet tooth” are equivalent, as are their plural forms (e.g. “teeth”). Analogous to a saw, each tooth includes a root (at the base arc), a face (extending generally radially outward from the base arc), a peak (at the top of the face), a gradually sloping portion from the peak back to the base arc, and generally triangular side walls.

As used herein, the expression “closure/container assembly” means a combination of the closure and the container to make a completed product. As used herein, the term “closure” means an object that closes the mouth of a container. As used herein, the term “container” means a receptacle for holding or carrying a material, the receptacle or container having walls that define a mouth or opening.

As used herein, the term “etc.” is indicative of a situation in which components similar to components previously listed may be present. For example, if three like components are listed, the term “etc.” indicates that there may be four or more similar components actually being referred to.

The expressions “removal force” and “removal torque” are used interchangeably and refer to the rotational force necessary to remove the closure from the container. This removal torque has two principal components: force necessary to overcome the initial sealing friction force and force necessary to break the tamper-band bridges. A third minor component is the force necessary to overcome thread friction. The sequential order of contribution of these component forces is not important.

Referring now toFIGS. 1-7, inclusive, a closure10comprises a top wall12, a side wall14, preferably cylindrical in shape, having an upper end16and a lower end18. Attached to the lower end18is a tamper-indicating band20, preferably cylindrical in shape, having an exterior major surface22, preferably cylindrical in shape, an interior major surface24, preferably cylindrical in shape, an upper edge26, and a lower edge28. Projecting from the upper edge26of the tamper-indicating band20is a series of rupturable or frangible bridges30a,30b,30c, etc. These rupturable bridges30a,30b,30c, etc., connect the tamper-indicating band20to the lower end18of the side wall14of the closure10. The rupturable bridges30a,30b,30c, etc., must be broken or ruptured to cause the tamper-indicating band20to separate from the side wall14to provide an indication of the opening of the container. Rupturable bridges30a,30b,30c, etc., are described, for example, in U.S. Pat. No. 4,981,230, incorporated herein by reference. Between the rupturable bridges30a,30b,30c, etc., are openings32a,32b,32c, etc. The purpose of the rupturable bridges30a,30b,30c, etc., is to attach the tamper-indicating band20to the lower end18of the side wall14. The purpose of the openings32a,32b,32c, etc., is to provide sufficient separation between the rupturable bridges30a,30b,30c, etc., to enable the rupturable bridges30a,30b,30c, etc., to be broken by a removal torque that can be generated by an elderly or arthritic user. The number of rupturable bridges30a,30b,30c, etc., formed around the circumference of the closure typically ranges from about five (5) to about fifteen (15). If the rupturable bridges30a,30b,30c, etc., are too narrow, they will be broken during production. If the rupturable bridges30a,30b,30c, etc., are too wide, the closure cannot be removed from the neck of the container without application of a significant amount of torque. For example, the rupturable bridges can range from about 0.003 inch to about 0.050 inch in width, assuming they are the full thickness of the wall in which they are formed. Of course, one skilled in the art will realize that the cross-sectional area is what contributes the bridge strength, so wider bridges may be employed if they are not the full thickness of the wall. Scoring the wall can produce rupturable bridges of this type.

Projecting from the lower edge28of the tamper-indicating band20is a series of tabs34a,34b,34c, etc. These tabs34a,34b,34c, etc. are substantially rectangular in shape. For the sake of simplification, tab34awill be described in detail. However, it should be noted that tabs34b,34c, etc., are substantially identical to tab34a. Tab34ahas an interior major surface36aand an exterior major surface38a. On the exterior major surface38aof tab34ais formed at least one sloping tooth40a. Typically, the aforementioned exterior major surface38aof tab34acontains two or more sloping teeth40aand40b. Tab34ais attached to the lower edge28of the tamper-indicating band20by a living hinge42a. The living hinge42ais designed so as to enable the tab34ato be folded, whereby the interior major surface36aof the tab34a, i.e., the major surface not bearing the teeth40aand40b, is generally flush against the interior major surface24of the tamper-indicating band20, and the exterior major surface38aof the tab34a, i.e., the major surface bearing the sloping teeth40aand40bfaces away from the tamper-indicating band20and radially inward toward the axis of the side wall14. As best shown inFIG. 7, the hinge42amay allow some spring in the folded tab34athat supplies a gentle pressure radially inwardly on the teeth40a, which helps keep them engaged with teeth116aon the container. The downward-facing end of each tab34a,34b, etc., that is distal, i.e. not attached to the tamper band20via the living hinge42, forms a surface35, the function of which is described later.

Between each set of adjacent tabs, e.g.,34aand34b, or34band34c, etc., is connecting bridge or connector44. The purpose of the connector44is to enable all of the tabs34a,34b,34c, etc., to be simultaneously folded up so as to contact the interior major surface24of the tamper-indicating band20. In addition, the connectors44maintain proper alignment between adjacent tabs34a,34b,34c, etc., so that consistent performance and consistent opening force is provided during the operation of removing the closure10from the neck of the container. There is a gap between each connector44and the lower edge28of the tamper-indicating band20to enable to living hinges42ato function with a low level of resistance to folding. In one variation (not shown) the connector44may exist near the distal ends of tab34aand34b, etc., whereby it can contribute to the surface35and optionally forms a continuous annular surface35that is a ring (not shown) in the closure10for purposes that will be described later. The width of the connectors44should be sufficiently low in order to reduce the force required to open the container. For example, the width of the connector44can be as low as 0.003 inch. However, the width of the connectors44must be sufficient in order to maintain adequate strength during the operations of filling the container and applying the closure10to the container. For example, the width of the connector44can be as high as 0.10 inch, and, as with the rupturable bridges, its strength depends on its width and thickness. Tabs34a,34b,34c, etc., and connectors44are described, for example, in U.S. Pat. No. 4,981,230, previously incorporated herein by reference.

In a first closure embodiment, the closure110is composite and is formed of two discreet parts: an annular side wall and a disk-like top wall that is captured within the side wall. As best shown inFIGS. 2,3and7, the side wall14has an interior major surface46and an exterior major surface48. In the interior major surface46of the side wall14positioned near the upper end16of the side wall14is a groove15, defined by an annular ridge17as a lower boundary and a curved upper wall portion16. This groove15receives a disk52having an interior major surface54and an exterior major surface56, which disk52forms the top of the closure110. The groove15is sufficiently wide so that the disk52can be rotated therein. This permits initial rotation of the closure without needing to overcome the resistance forces associated with unsealing the container. For reasons described in prior patents, e.g. U.S. Pat. No. 4,813,561, the disk52may optionally contain an annular downward facing U-shaped lip as shown inFIG. 7, which fits into the groove15. At the peripheral edge of the inner major surface54of the disk is a layer58of oxygen-impervious, moisture-impervious polymeric sealant material, which functions as a gasket or seal.

In a second closure embodiment, shown inFIG. 9, the side wall214and top wall216of the closure210are integrally formed as one piece. Side wall214contains downwardly depending tabs234that contain sloping teeth240a,240b, etc., just as in the two-part embodiment. The structure and function of the one part closure is similar in many respects to the two part closure: including the teeth interaction with the container, the tamper band, hinges and bridges, so these details are not repeated here. What differs with the one-part closure210is the sealing surface258and the rotational force analysis. With a one part closure210the initial removal torque must overcome the sealing friction force. For this reason, it is desirable to use sealant polymers on the sealing surface258that can provide good sealing properties and yet maintain minimal friction forces upon twisting. Selected polymers that can achieve this are described below.

In either embodiment, the interior major surface46of the side wall14contains thread(s)60, which mate with thread(s)108on the neck of the container, which will be described in detail later.

Referring now toFIGS. 4-8, inclusive, a container100suitable for use with the closure10or the closure210described herein typically comprises a body102having walls defining a neck104. The neck104of the container100surrounds the mouth106of the container100. The neck104of the container100comprises thread(s)108, which mate with the thread(s)60on the interior major surface46of the side wall14of the closure10,210. The start of the thread(s)108is designated by the reference numeral109. Also on the neck104of the container100are a set112aof sloping teeth114a,114b,114c,114dand a set112bof sloping teeth116a,116b,116c,116d. InFIG. 8, two sets112a,112bof sloping teeth are shown; however, more sets of sloping teeth, each set separated from the other by a gap, or even a continuous ring of teeth (not shown) can be formed on the neck104of the container100. Sloping teeth114a,114b,114c,116a,116b,116c,40a,40bare described, for example, in U.S. Pat. No. 4,813,561, incorporated herein by reference.

The teeth are designed opposingly, such that the tooth face of teeth on one component (e.g. the container) provides a catching surface for engaging the tooth face or ratchet on an opposing component (e.g the closure tamper band). However, neither the directionality nor the ordering of the teeth is otherwise critical. It is also noted that one side wall of the teeth can also form a surface35, shown as a discontinuous surface inFIGS. 1 and 2

As best seen inFIGS. 4 and 7, the neck104of the container100further comprises an annular retaining ledge or bead120. The retaining bead120has a downward facing lower surface122that is positioned to engage the surface35of the tabs34, once they have been folded back into position inside the closure. This lower surface122, unlike the threads108, is in a plane that is approximately perpendicular to the axis of the container neck. The interference fit of the lower surface122of annular bead120against the distal surface35of the folded tabs34(seeFIG. 7) prevents removal of the tamper-indicating band20when the closure10is removed from the neck104of the container. As is described later in connection with operation, this interference fit is also the mechanism for breaking the rupturable bridges30a,30b, etc., upon removal of the closure10. In the embodiment shown, the retaining bead120completely encircles the neck104of container100, however this is not an essential feature. In the embodiment shown, the retaining bead120is annular, extending continuously around the circumference of the neck, however, it may well be intermittent and discontinuous around the periphery, provided at least one of the lower surface122of the bead120or the distal surface35of the tabs34a,34b, etc., is substantially continuous and annular.

Although the sloping teeth114a,114b,114c,114dand the sloping teeth116a,116b,116c, and116d(and optionally other sets of sloping teeth similar to114a,114b,114c,114d,116a,116b,116c, and116don the neck104of the container100) engage the sloping teeth40aand40b(and optionally other sets of sloping teeth similar to40aand40bon the closure10), the sloping teeth on the neck104of the container100are angularly offset slightly from the sloping teeth on the tabs34a,34b,34c, etc. This is best shown inFIG. 6, where the closure teeth40a,40b, on each tab34a,34b, etc., are staggered or offset from the teeth116a,116b,116c, etc., of the container100. If each the sloping teeth116a,116b,116c, and116d(and optionally also teeth114a,114b,114c, and114d) are positioned so that a given tooth arc (i.e. the arc distance from one tooth peak to the next tooth peak) occupies θ° of the circumferential arc of the neck104of the container100, then the sloping teeth40aand40bon the tab34aare positioned with a different angular interval such that the tooth arc of a given tooth40adoes not occupy θ° or an integral multiple of θ° of the circumferential arc formed by the tabs34a,34b,34c, etc., of the closure10. In an exemplary embodiment, if each of the sloping teeth114a,114b,114c, and114dand each of the sloping teeth116a,116b,116c, and116dare positioned so that a given tooth arc occupies 10° of the circumferential arc of the neck104of the container100, then a given tooth arc40a,40bon a tab34can occupy, for example, 12.5° of the circumferential arc formed by the tabs34a,34b,34c, etc., of the closure10, creating an angular delta or offset of 2.5° in the angular spacing of the two sets of teeth.

The angular spacing is not limited to 10° for sloping teeth114a,114b,114c, and114dand sloping teeth116a,116b,116c, and116don the neck104of the container100. This angular spacing simply permits 36 teeth circumferentially around the container100. Greater or fewer teeth may be spaced about the circumference according to the known formula: No. of teeth desired/360 gives the angular spacing (for continuous teeth). Nor is the offset delta limited to 2.5° for sloping teeth40a,40bon the circumference formed by the tabs34a,34b,34c, etc., of the closure10. These are simply examples. The offset for the closure teeth40a,40b, can be, for example, any angle or fractional angle that is not an integer multiple of the angular spacing of the container teeth (e.g.116a,116, b, etc.). Typical offset deltas may be, for example, between 0.1° and 10°, more commonly between 1° and 5°. However, as noted, if the teeth on container occupy θ° of the circumferential arc, then the offset delta cannot be nθ°, where n is an integer, or else the desired staggering of the teeth is defeated. Offsetting the sloping teeth40aand40bon the tabs34a,34b,34c, etc., of the closure10from the sloping teeth114a,114b,114c, and114dand sloping teeth116a,116b,116c, and116don the neck104of the of the container100provides at least two advantages:(a) lower removal torque(b) greater strength to with stand the backoff forces encountered during production and distribution
It should also be noted that any two adjacent sloping teeth, e.g.,114a,114b, on the neck104of the container100or any two adjacent sloping teeth, e.g.,40aand40b, on a tab34aneed not abut one another. Adjacent sloping teeth e.g.,114a,114b, on the neck104of the container100or adjacent sloping teeth on a tab34acan be separated by a small angular distance, such as, for example 1° of arc. However, the requirement specified previously for the offset must be adhered to in order to obtain the benefits of the closure described herein.L=length of arc on the circumference of the closure in degrees and length of arc on the circumference of the neck104of the container100in degreesntc=number of teeth in the at least one set of sloping teeth in the arc L on the closure10ntb=number of teeth in the at least one set of sloping teeth in the arc L on the container100
In order to ensure that the at least one set of teeth on the closure only partially engages the at least one set of teeth on the neck104of the container100, it is preferred that ntcnot be equal to equal to ntband that L/ntcnot be equal to L/ntbAs a representative example, if L=50°, then ntc=5 and ntb=4. As can be seen inFIG. 6, the arc L contains five teeth40a,40b,40a,40b, and40aof the closure and four teeth116a,116b,116c, and116dof the container100.

If reducing removal torque were the sole consideration, it would be preferred that all of the teeth in all of the sets of teeth on the neck104of the container100be offset from the teeth of the closure10with which they are partially engaged, or even that no teeth at all existed. However, without at least partial engagement of some teeth in of the container100with teeth of the closure10, the risk of “back off” increases unacceptably. The present invention is a unique compromise between these conflicting concerns. Accordingly, it is preferred that at least one, but not all, of the teeth in each set of teeth on the neck104of the container100be completely engaged with a tooth on the closure10, so that removal torque is reduced from the situation in which all of the teeth in each set of teeth on the neck104of the container100are engaged, while “anti-back off” features are still retained. For example, if the neck104of the container100contains two sets of teeth positioned 180° apart and each set of teeth contains four teeth (as depicted inFIG. 8), it is preferred that at least one of the four teeth in each set of teeth be completely engaged with a tooth on the closure10and that the remaining teeth be not engaged or only partially engaged with the teeth on the closure10. While two sets of teeth are depicted in the embodiment ofFIG. 8, it will be understood that from one set to about 12 sets may be used about the circumference of the neck, depending on the sizes and number of teeth per set. Indeed a continuous row of teeth is possible as well, although 2-6 sets seem preferable.

Referring toFIG. 6, it can be seen that tooth40aof the closure tamper band20is completely engaged with tooth116aof the container. During the undesirable backoff process, this tooth may become disengaged, allowing the closure and tamper band20to slip counterclockwise past this point until a subsequent tooth engages. By staggering the teeth as described above, the next most likely teeth to become engaged will be closure tooth40athat is already nearly engaged with container tooth116din the figure, rather than the next adjacent closure tooth,40b, engaging with container tooth116a. This minimization of backoff rotation tends to preserve the necessary sealing of the container, while providing easier removal torque. Optionally, two or more teeth of each set of four teeth on the neck104of the container100can be completely engaged with teeth on the closure10, however, it should be noted that as more teeth of each set of teeth on the neck104of the container100are engaged with teeth of the closure10, the amount of force required to remove the closure10increases.

The material of the closure10can be any polymeric material capable of being molded, cut, folded, and assembled to form the closure10described herein. Representative examples of polymeric material suitable for preparing the closure10include, but are not limited to, polyolefins, such as, for example, polypropylene and polyethylene. Other polymeric materials, such as, for example, polycarbonate, polyvinyl chloride, polystyrene, polylactic acid, synthetic elastomers, natural latex rubbers, polyesters, such as, for example, polyethylene terephthalate, nylon, and similar materials.

Materials that are suitable for preparing the disk52that is inserted in the groove15in the two part closure110are capable of being formed, stamped, cast, or molded into shapes having specified surface dimensions and width dimensions and that exhibit specified flexibility or rigidity. Representative examples of materials suitable for preparing the disk52include, but are not limited to, metals, composite materials comprising metal, other composite materials not comprising metal, or polymeric materials comprising a single layer or a plurality of layers laminated together. Representative examples of metals suitable for preparing the disk52include, but are not limited to, stainless steel, tin-free steel, aluminum, metal composites containing carbon, and other composite materials. Representative examples of polymeric materials suitable for preparing the disk52include, but are not limited to, polyolefins, such as, for example, polypropylene and polyethylene. Other polymeric materials, such as, for example, polycarbonate, polyvinyl chloride, polystyrene, polylactic acid, synthetic elastomers, natural latex rubbers, polyesters, such as, for example, polyethylene terephthalate, nylon, and similar materials.

Properties of metal disks that can be used in the closure of this invention are described, for example, in U.S. Pat. No. 4,991,731, incorporated herein by reference. See column 4, line 53 through column 5, line 24 of U.S. Pat. No. 4,991,731. The disk described in U.S. Pat. No. 4,991,731 further contains a fusible coating on the major surface thereof facing the contents of the container100. Disks suitable for use herein can also have such a fusible coating on the major surface thereof facing the contents of the container100or on both major surfaces thereof. Such fusible coatings for metallic disks include, but are not limited to, epoxy coatings, enamel coatings. Another coating material suitable for composite disks or polymeric disks is ethylene vinyl acetate. It is not required that the disk have a fusible coating on one or both major surfaces thereof.

The gasket58that is placed around the peripheral edge of the disk is a polymeric material that is capable of creating a hermetic seal by means of terminal sterilization at a temperature of up to 275° F. Representative examples of polymeric materials suitable for preparing the gasket58include, but are not limited to, polymeric materials comprising a single layer or a plurality of layers laminated together, which materials can be formed, stamped, cast, or molded into shapes having specified surface dimensions and thickness dimensions. Representative materials suitable for preparing the gasket58include, but are not limited to, polyolefins, such as, for example, polypropylene and polyethylene, polystyrene, polylactic acid, synthetic elastomers, natural latex rubbers, polyesters, such as, for example, polyethylene terephthalate, nylons and other soft to rigid materials modified for a specified value of durometer. U.S. Pat. No. 4,981,230, previously incorporated herein by reference, discloses plastisols for preparing the gasket58. A typical plastisol is a polyvinyl chloride resin that is applied from a solvent.

The choice of material for gasket58,258may depend on the type of closure: one part or two. For reasons related to the operation of the assembly, gasket58in the two-part closure110may be a softer, more deformable material to create an effective seal. Friction is not a major concern since the disk52is lifted from the container. However, in the one part closure210, the rotational torque must unseat the gasket258and break the seal. To overcome this additional friction component of the torque, gaskets and polymers that reduce friction are preferred in the one part closure210. Plastic polymers and/or gaskets that are modified with the addition of slipping agents. Slipping agents that are suitable for this friction-reducing purpose include waxes, such as Euricimide®, and polyfluorinated polymers, such as Teflon® brand PTFE and related co-polymers. Alternatively, the container may be hermetically sealed by a foil layer, and slipping agents may be used with the foil and the plastic polymers of the closure to reduce the friction. In another alternative, reducing the area of the contact surfaces, for example, by making the sealing surface of the neck very thin can reduce friction. This alternative introduces a tradeoff with ensuring a hermetic seal however.

The container100is preferably made of a polymeric material that is a single layer material or a multiple layer material that can be formed, stamped, cast, or molded into a shape having specified dimensions and specified wall thicknesses. The polymeric material can be either flexible or rigid. Representative example of polymeric material suitable for preparing the container100include, but are not limited to, polyolefins, such as, for example, polypropylene and polyethylene, which polyolefins can optionally be blended with ethyl vinyl alcohol, ethylene vinyl acetate, polyvinylidene chloride (saran), Surlyn® resin, Admer® resin, or similar barrier and adhesive layers. Other polymeric materials, such as, for example, polycarbonate, polyvinyl chloride, polystyrene, polylactic acid, synthetic elastomers, natural latex rubbers, polyesters, such as, for example, polyethylene terephthalate, nylon, and similar materials can also be used.

In place of a series of rupturable bridges30a,30b, etc., between the tamper-indicating band and the lower portion of the side wall, a line of weakness can be formed between the tamper-indicating band and the lower portion of the side wall. Upon removal of the closure from the container100, the tamper-indicating band will separate from the lower portion of the side wall along the line of weakness. The line of weakness and method for forming a line of weakness is described in U.S. Pat. No. 4,813,561, incorporated herein by reference.

A tamper-indicating band20can be provided to the lower end18of the side wall14by means of a mold that has been designed for that purpose. Then, an appropriate blade can be used to form the openings32a,32b,32c, etc., adjacent to the rupturable bridges30a,30b,30c, etc. The blade can be a component of the mold or can be provided separately from the mold. In lieu of the use of rupturable bridges30a,30b,30c, etc., it is suitable, but not preferred, to employ a score line (not shown) to form a weakened region between the tamper-indicating band20and the lower end18of the side wall14.

Containers and methods for making thereof are described in U.S. Pat. Nos. 4,349,116; 4,991,731; 5,004,110; and 5,217,737, all of which are incorporated herein by reference.

Conventional closure application machinery can be used to apply the closure10to the container100. Specifically, capping machinery would have grasping elements commonly known as capping chucks to grasp and hold the closure10in a position above the neck104of the container100for placement of the closure10onto the neck104of the container100. Prior to applying the closure10to the container100, the tabs343a,34b, and34c, etc., are folded so that the teeth40a,40b, face radially inward toward the axis of the side wall14. The capping chucks are driven by a suitable source of energy, and suitable mechanical linkages are utilized to spin the chuck at the appropriate speed to apply the closure10to the neck104of the container100. The capping chuck must also have the means for limiting the rotational force and terminating the capping operation once the closure10has sealed the container100but not advanced so far as to rotate beyond the available thread(s)108on the neck104of the container100or the available thread(s)60on the interior major surface46of the side wall14of the closure10.

Operation

To open the container100described herein, an individual grasps the closure10and twists so as to apply sufficient removal torque to the closure10. On account of the offset of all but at least one of the sloping teeth in the sets of sloping teeth on the neck104of the container100relative to the sloping teeth on the closure10, the removal torque can be as low as 3 inch pounds on average, and is typically less than 18 inch pounds on average, more likely less than 16 inch pounds on average. This low level of removal torque renders the assembly of the closure and the container100described herein suitable for use by arthritic users and elderly users. An unbroken tamper-indicating band20assures the user that the assembly of the closure10and the container100has not been subject to tampering. As the closure is twisted off, the torque must overcome both the sealing friction, which is higher in the one-part cap embodiment, the tamper band force and the thread friction force.

As removal torque is applied to the closure10, the closure10rides upward on the threads on the neck104of the container100pulling the attached tamper band20in an upward axial direction. However, the retaining band120catches the sloping teeth40a,40b, etc., which resists the upward pulling on the tamper band20, thereby causing an axial stretching force on the rupturable bridges30a,30b, etc. As the closure10continues to ride up the thread, this axial stretching force eventually causes tearing or breaking at the rupturable bridge in the vicinity of greatest stretch. As the closure continues upward on the threads, additional rupturable bridges are broken, but in a sequential or serial manner, thus reducing the torque necessary to remove the closure. Once the last rupturable bridge is broken, the tamper-indicating band20separates from the lower end18of the side wall14of the closure10. The retaining bead120enables the container100to retain the tamper-indicating band20on the neck104of the container100.

The threads on the container100and the threads on the closure10can have the shape shown inFIGS. 4 and 7, in which the bottom surface of the thread(s)108of the neck104of the container100and the top surface the thread(s)60of the closure10are made relatively flat and, in a radial dimension, horizontal. (They of course have a pitch in a circumferential direction.) The result is that any relative movement between the thread(s)60and the thread(s)108during a retorting operation caused by the unequal expansion of the closure10and the container100causes an insignificant relative vertical movement between the thread(s)60and the thread(s)108so that the threads retain their vertical tension for both heated and cooled packages. Threads for closures and containers are described in further detail in U.S. Pat. No. 4,813,561, incorporated herein by reference.

For the embodiment of the two-part closure110shown inFIGS. 2,3and7, a further advantage is obtained, whereby the torque necessary to stretch and break the rupturable bridges30a,30b, etc., is at least partially distinct from the torque necessary to overcome the friction of the seal. In this embodiment, the disk52can remain seated on the mouth106of the neck104of the container100until it is lifted from the mouth106by the annular ridge17on the interior surface46of the closure side wall114. If the depth of the groove15is sufficient, a significant portion of the rupturable bridges30a,30b, etc., may be broken before the annular lip17engages disk52and the friction of the seal adds a component of torque to lift the disk52off the mouth106of the container100.

Operation as described above as an opening process and that is consistent with the main problem being addressed, which is the balancing of tradeoffs between sufficient backoff protection while maintaining an opening torque that is acceptable to persons who have difficulty opening containers, such as persons who are elderly or afflicted with arthritis. However, it is also to be appreciated that that closure must be installed on the container in the first place, substantially without breaking the very same rupturable bridges of the tamper indicating band. Although some rupturable bridges may be broken, it is a matter of process control to minimize the installation breakage to a acceptable levels, so allow the tamper resistance feature to be realized. This can be achieved by one or more of several mechanisms.

In a first mechanism, the tolerances of the container and the closure are tightly matched so that the closure10fits over the retaining bead120just barely, and subsequent deformations of the tamper indicating band20allow it to catch on the retaining bead120. A second mechanism, best shown inFIG. 7, provided a slight springiness in the living hinge42a, which allows the folded tabs34a,34b, etc., to be pushed against interior surface36aof the tamper indicating band20, allowing the associated teeth40a,40b, etc to deflect radially outwardly over the retaining bead120as the closure10is forced down onto the container100, but still allows the teeth40a,40b, etc., to spring back radially inwardly to catch the under surface122of the retaining bead120when the closure is removed. Finally, the closure and/or container may be heated to soften the plastic polymers to allow for expansion and deformation and spring of all the components. It may be preferable to use all these techniques to install closures on the containers in the first place with and acceptable number of rupturable bridges still intact.

The removal torque was measured for closure assemblies made according to the invention and compared with removal torques of prior art closure assemblies. The removal torque for prior art closure assemblies had a typical removal torque of about 17-18 inch pounds, whereas the removal torque for closure assemblies according to the invention had a typical removal torque of about 9-10 inch pounds.

Closure assemblies like those of example 1 and a third closure assembly having a removal torque of about 23 were tested in interviews with 164 actual users. The users were grouped into three categories: mothers of young children (N=54), arthritics (N=75) and independent-living seniors (N=35). Each user was asked to open each of the three container-closure assemblies in a balanced complete block statistical design (to eliminate sequence bias), and users were asked to rank the assemblies on two parameters: Difficulty of opening was ranked on a scale of 1 to 9 (1=not at all difficult, 9=extremely difficult); and overall “Acceptability” was ranked from 1 to 9 (1 to 5.0 deemed acceptable; 5.1 to 9 deemed unacceptable).

Mean data is presented in the table below.

It can be seen from the data that the closure assembly of the invention was judged far easier to open, especially for the seniors and arthritics. Overall acceptability was also significantly higher with the closure assembly of the invention.

This invention allows the removal torque of a closure to be controlled at a low level, such as, for example less than 16 inch pounds on average. The invention also allows an audible feature as the closure is being rotated. This closure is particularly useful for both elderly and arthritic patients.

The closure/container assembly described herein can be utilized in any closure/container assembly intended to be used by either elderly or arthritic patients.

Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth herein.