Abstract:
A molded plastic container and closure is provided with a double lock, the top lock being formed by the container rim and a protrusion on the inside of the closure channel. The bottom lock is formed by a segmented flange on the container sidewall and a second annular protrusion on the inside of the closure skirt. A zig-zag tear line allows the second lock to be removed thereby to create alternating areas of greater and lesser clearance between the newly formed skirt edge and a second, lower flange on the container sidewall.

Description:
FIELD OF THE INVENTION 
     This invention relates to molded plastic containers and closures and more particularly to a closure having a tear-band which, when torn away, makes the closure easier to remove from the container. 
     BACKGROUND OF THE INVENTION 
     It is known to provide plastic shipping containers and closures with secure locking arrangements which require some type of physical alteration to the closure structure before it can be easily removed from the container. For example, some closures are provided with small apertures in the peripheral skirt to permit the skirt to be split or fractured at several circumferentially spaced locations. The loss of integrity in the skirt allows sections of it to be pulled outwardly such that they pass more readily over a locking flange formed on the top of the container when one wishes to remove the closure from the container. 
     Another example of a closure requiring physical alteration for removal is the tear-band closure. The skirt portion of this type of closure is provided with a circumferential tear line of structural weakness which allows a lower portion of the skirt to be torn away thus to eliminate some or all of a locking arrangement between the container and closure. 
     Both the fracturable skirt closure and the tear-band closure have the characteristics of providing a strong lock when first applied, providing evidence of tampering, and providing a measure of resealability even after the locking structure has been altered or removed. 
     SUMMARY OF THE INVENTION 
     This invention is described with reference to a molded plastic container/closure combination of the type having a tear-band in the closure skirt for removability. The invention provides a strong pre-tear lock and seal, a strong post-tear seal and improved post-tear removability. 
     In general, the invention is applied to a plastic container having an outwardly formed top rim and first and second ring-like outwardly-extending flanges formed on the container sidewall at first and second locations below the top rim. The closure is of the type having an inverted U-shaped peripheral channel which receives the container rim therein and seals thereto when fully set in place. The outermost interior wall of the closure channel is provided with first and second circumferentially continuous, inwardly extending protrusions, the top-most of which coacts with the container rim to provide a first lock and the lower-most of which coacts with the top ring-like flange on the container outer sidewall to provide a second lock. The lower sidewall flange is closely adjacent the bottom of the closure skirt to make it difficult or impossible to pull outwardly on the skirt. 
     A tear line; i.e., a line of structural weakness which is more easily torn or fractured than the balance of the closure skirt, is formed in the skirt between the upper and lower protrusions such that physical removal of the tear-band eliminates the second lock thereby facilitating removal of the closure from the container. 
     In the preferred embodiment disclosed herein, the tear line is irregular or zig-zag in design thereby to create a plurality of circumferentially spaced tabs or grasp areas which extend toward but are spaced from the topmost of the flanges. The topmost flange is preferably made discontinuous or segmented as to provide spaced areas of maximum clearance between the grasp tabs and the bottom-most side flange. The closure and lid are designed so that such areas of maximum clearance are guaranteed to occur no matter what the angular relationship between the closure and the container when the closure is applied. 
     Also in the preferred embodiment, the inner wall of the closure is made deeper than normal and fits against a step in the inner container wall to stabilize the closure under heavy loading conditions such as occur when filled containers are stacked. 
     Other arrangements for applying the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
     FIG. 1 is a side view of a container and closure combination prior to assembly of same; 
     FIG. 2 is a sectional view of a portion of the FIG. 1 structure showing the relationship of the container and closure after assembly of same but before removal of the tear-band; 
     FIG. 3 repeats the FIG. 2 view but with the tear-band partially removed; 
     FIG. 4 shows the assembled container and closure combination with the tear-band removed; 
     FIG. 5 is a diagrammatic sketch of the container and closure of the present invention when under compression due to stacking of the containers; and 
     FIG. 6 is a plan view of the closure of the present invention showing a plurality of circumferentially spaced tabs. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown an injection molded plastic container  10  of tapered, cylindrical configuration. Container  10  may be manufactured from any of a variety of plastics including high density polyethylene in any or all of a variety of sizes including, by way of example only, four and five gallon sizes. Container  10  has an open top defined by an outwardly and downwardly turned rim  12 . High density polyethylene is a suitable material but other plastics may be used. 
     Spaced below the rim  12  and at first and second vertical distances therefrom along the container sidewall are ring-like circumferential flanges  14  and  16 . Flange  14  is segmented and in this embodiment is made up of eight segments with eight gaps  44  or vacancies between them. In a four-gallon container, the flange  14  is about ¾″ below the rim  12 . Flange  16  is circumferentially continuous, is radially larger than flange  14  and is about ½″ below flange  14 . Both flanges  14  and  16  are angled downwardly in side profile. 
     Container  10  is further provided with a pair of diametrically opposite bail-receiving structures  18  and a third circumferential flange  20 . A wire bail may be assembled to the structures  18  in a known manner. 
     FIG. 1 further shows a closure  22  which may also be injection molded of high density polyethylene or other suitable plastic material. The closure  22  has an outer skirt  24  which, when the closure is applied as shown in FIG. 2, overlies the rim  12  and a portion of the upper container sidewall. A zig-zag tear line  26  is formed in the skirt  24 . 
     Referring to FIG. 2, this enlarged detail view shows the fact that the flanges  14  and  16  are preferably downwardly angled at about 16° to 20°. FIG. 2 also shows the container rim  12  to have a smooth, rounded top surface. The interior sidewall has a step  28  formed therein about 2″ below the rim  12 ; i.e., opposite the flange  14 . 
     FIG. 2 shows closure  22  to exhibit an inverted, U-shaped channel defined by and between an inner leg  30  and the skirt  24 . When applied to the container  10 , the inner leg  30  lies against the interior sidewall of the container  10  and rests on the step  28 . The top interior surface of the closure channel is provided with flexible seal ridges  32  which sealingly bear against the smooth top surface of rim  12  when the closure is applied to the container  10 . 
     A first annular locking protrusion  34  is formed on the interior surface of the closure channel to underlie the rim  12  and provide a first lock between the closure  22  and rim  12  of container  10 . A second annular protrusion  36  is formed on the bottom of skirt  24  to coact with the flange  14  to provide a second, stronger lock between the container and closure. In the applied and integral condition, the bottom of the skirt  24  lies closely adjacent the bottom flange  16  and at approximately the same radial distance from the container sidewall. This limits access to the skirt bottom and makes removal of the closure more difficult before the tear band is removed. 
     The closure  24  is the reentrant type; i.e., it has an annular wall portion  38  which extends into the container interior to provide a flat center section  40  on which the bottom of a second container  10  can rest when stacked on the closure of a lower container. 
     Referring now to FIGS. 1,  3 ,  4  and  6 , access to the content of container  10  is gained, alter the closure  22  is filly applied, by removal of the tear band; i.e., the strip-like portion of the skirt  24  which lies below the tear line  26 . A starter tab  42  is formed by an L-shaped slot molded into the closure  22  as shown in FIG.  1 . Removal of the tear-band results in the structure shown in FIG. 4; i.e., the portion  36  defining the bottom lock has been removed. Because the tear line  26  is of a zig-zag design, removal of the tear band results in the definition of three spread tabs  46  which at least partially overlie gaps  44  in the segmented flange  14 . The gaps allow the user to grasp and pull the tabs  46  outwardly and upwardly to remove the closure from the container. Because the number of gaps  44  is greater than the number of tabs  46 , at least two tabs will overlie gap  44  no matter what the angular orientation of the closure  22  when applied to the container  10 . 
     Referring now to FIG. 5, when weight is placed on the closure  22 , such as when containers are stacked, the force is transmitted down the annular support wall  30  to the step  28  located on the inside of the container wall. The point of contact between the annular support wall  30 , and the step  28 , remains stationary while other lid features generally flex or rotate about it. The annular support wall  30 , being flexible, bends and flexes into the wall of the container  10 . Clearance vents  50  are located periodically about the lower portion of the annular support wall  30  to prevent air from being trapped between the closure and pail. The inner leg  52  rotates towards the stacked container  10  until it comes into contact with the lower wall of the stacked container  10 . This contact prevents further rotation of the lid  22  flexing around the container rim  12 . Circumferential ribs  32  move but remain in contact with the container rim  12 , thus maintaining the sealed condition. The lock created by protrusion  34  and rim  12  remains intact. The tear line  26  acts as a hinge, allowing the lower portion of the skirt  24  to bend relative to the upper portion. The locking projection  36  located on the lower portion of the skirt  24  maintains contact with the locking flange  14 . The locking flange  14  is deflected upward, thus increasing the contact length with locking projection  36  and enhancing the engagement between the locking flange  14  and the locking projection  36 . The protection flange  16  continues to protect the closure  22  from accidental disengagement and to prevent accidental damage to the lower portion of the skirt  34 . 
     After delivery of the sealed and filled container  10  to an end user, the user opens the container  10  by first removing the tear band, as shown in FIGS. 3 and 4. The closure  22  is removed by bending the upper skirt portion  46  away from the container  10  and providing a force in an upward direction. The projection  34 , which forms a weaker lock, is pulled over the rim  12  of the container  10 , allowing the closure  22  to be disengaged from the container  10 . Upon reclosing the container  10 , the closure  22  is pressed until the projection  34  lockingly engages with the rim  12  of the container  10 . 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.