Patent Publication Number: US-2009236354-A1

Title: Can closure arrangement

Description:
FIELD OF THE INVENTION 
     The present invention refers to a closure arrangement for cans obtained in sheet metal and of the type which comprises a tubular body inferiorly closed and carrying an annular upper wall, having an inner edge which defines an upper opening for the can and which is configured to define a closure seat in the form of a convex arc, in which is removably seated and axially retained a single piece lid made of plastic material or sheet metal. 
     PRIOR ART 
     Determined products, such as certain food products, require packages that can remain hermetic for long periods of storage, avoiding the entrance of air, as well as the contamination and oxidation of the stored product. 
     Apart from the requirements above, determined products, such as certain food products, are of progressive consumption and require the can lid to be of the reclosable type, so that it may be reclosed as many times as needed during the progressive consumption of the stored product, in order to guarantee the tightness of the can and protect the remaining content thereof. 
     Furthermore, in certain cases, besides the tightness required for long periods of storage and the characteristics of progressive consumption, it is desired that the can lid may be easily opened with no need of using auxiliary tools or instruments, such as keys, cutlery handles, etc., the first opening thereof being achieved by breaking a tamper evident seal. 
     The known lids which are press-fitted in a structural ring double-seamed to an upper edge of the side wall of the can tubular body do not present the tightness required to guarantee, by themselves, long periods of storage, and many times it is necessary to provide a hermetic tamper evident seal until the occurrence of the first opening, said seal being generally defined by an aluminum foil or other suitable material that is double-seamed to the upper edge of the side wall of the can jointly with the annular upper wall. 
     This known solution requires tools for opening the lid, as well as for cutting the tamper evident seal upon the first opening of the can. 
     There are also known from the prior art the lids constructed in sheet metal or in plastic material and which are peripherally provided with a circumferential groove with its cross section generally in the form of a concave arc turned outwardly and which is seated and axially retained in a closure seat provided in the peripheral inner edge of the annular upper wall of the tubular body of the can. The seating of the circumferential groove of the lid on the closure seat in the form of a concave arc allows obtaining a sealing region that also operates as a region for axially retaining the lid to the tubular body of the can. 
     Although the solution cited above, which is described in Brazilian patent application PI0203950-8 of the same applicant, guarantees a safe axial retention of the lid to the tubular body of the can with a high degree of tightness in this sealing region, said sealing region does not guarantee a degree of tightness sufficient to comply with the storage requirements of certain products for long shelf periods, as it occurs with food products to be exported and which present hydroscopic characteristics and become easily oxidized when in contact with the oxygen of the ambient air. 
     SUMMARY OF THE INVENTION 
     Due to the limitations found in the known constructive solutions, it is an object of the invention to provide a can closure arrangement which guarantees a high degree of tightness for long periods of storage, as well as the facility for opening the lid without using special tools and for manually reclosing it, guaranteeing the same degree of tightness until the first opening. 
     It is a further object of the invention to provide a closure arrangement as mentioned above, which evidences the first opening of the can. 
     The present closure arrangement is applied to cans comprising a tubular body made of sheet metal and which is inferiorly closed and carries, by double-seaming or deformation or any other fixation means, an annular upper wall having an inner edge which defines an upper opening for the can and which is bent in such a way as to define a closure seat in the form of a convex arc. 
     The closure arrangement object of the present invention further comprises a lid generally formed in a single piece and comprising a base portion dimensioned to cover said upper opening, a peripheral portion provided with a circumferential cradle, whose cross section is in the form of a concave arc and which is dimensioned to be fitted and axially retained against the closure seat when the lid is seated on the upper opening of the can, and an annular portion projecting radially outwardly from the peripheral portion and to be seated onto the annular upper wall upon closure of the lid. 
     According to the invention, at least one of the parts of annular upper wall of the tubular body and annular portion of the lid carries an annular gasket to be pressed by the other part upon closure of the lid, so as to define a respective annular sealing region between the lid and the tubular body. 
     The provision of said second annular sealing region between the lid and the tubular body, generally positioned radially externally to the closure seat, allows reaching a high degree of tightness upon closing the lid to the tubular body of the can. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described below with reference to the enclosed drawings, given by way of example of possible constructions of the invention and in which: 
         FIG. 1  represents a perspective view of a possible construction for a plastic lid to be used in the closure arrangement of the present invention and incorporating a seal portion; 
         FIG. 1   a  represents an exploded perspective view of the lid of  FIG. 1  after its first opening; 
         FIG. 2  represents a partial diametrical cross-sectional view of the lid illustrated in  FIG. 1  and mounted to the upper end of a can, taken along line II-II of  FIG. 1  and illustrating a first embodiment for the closure arrangement of the present invention; 
         FIG. 3  represents a view similar to that of  FIG. 2 , but illustrating a second embodiment of the closure arrangement; 
         FIG. 4  represents a view similar to those of  FIGS. 2 and 3 , but illustrating a third embodiment of the closure arrangement of the invention; 
         FIG. 5  represents a view similar to those of  FIGS. 2 ,  3  and  4 , but illustrating a fourth embodiment of the present closure arrangement, in which the annular gasket is carried by the lid; 
         FIG. 6  represents a view similar to that of  FIG. 5 , but illustrating a fifth embodiment of the present closure arrangement; 
         FIG. 7  represents a diametrical sectional view of another can-lid construction in sheet metal utilizing the closure arrangement of the present invention according to the embodiment of  FIG. 2 ; 
         FIG. 7   a  represents a view similar to that of  FIG. 7 , but illustrating a metallic lid with its annular portion incorporating a circumferential rib; 
         FIG. 7   b  represents a sectional view showing enlarged details of the closure arrangement of the can-lid construction illustrated in  FIG. 7   a;    
         FIG. 8  represents a diametrical sectional view of a metallic can—plastic lid construction incorporating a seal portion and utilizing the closure arrangement illustrated in  FIG. 2 ; 
         FIG. 8   a  represents a view similar to that of  FIG. 8 , but illustrating the application of a plastic lid provided with a seal and with its annular portion incorporating a circumferential rib; 
         FIG. 8   b  represents a sectional view with enlarged details of the closure arrangement of the can-lid construction illustrated in  FIG. 8   a ; and 
         FIG. 9  represents a view similar to that of  FIG. 8   a , but presenting a constructive variant for the upper edge of the side wall of the can. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-6  illustrate a can construction with a tubular body  10  of sheet metal, to be superiorly closed by a lid  20  made in a single piece of plastic material, said can being provided with the closure arrangement object of the present invention. 
     As illustrated in the sectional views of  FIGS. 2-6 , the generally cylindrical tubular body  10  comprises a side wall  11  presenting an upper edge  11   a , said tubular body  10  being inferiorly closed by a bottom wall (not illustrated) that is incorporated in a single piece, or double-seamed, or otherwise affixed to the side wall  11 . 
     According to  FIGS. 2-6 , the tubular body  10  of the can further comprises an annular upper wall  12  peripherally affixed to the upper edge  11   a  of the side wall  11  through a double-seam  13 , said annular upper wall  12  having an inner edge  12   a  defining an upper opening A in the can and which is generally upwardly and radially outwardly bent, defining a tubular rib  14  defining a closure seat S presenting a cross section in the form of a convex arc. 
     As it will be better understood with the description of the embodiments illustrated in  FIGS. 7 and 8 , there is no need for the inner edge  12   a  of the annular upper wall  12  to be bent to define the tubular rib  14 , it being suffice that said bending forms a seat S, having a cross section in the form of a convex arc. 
     The can, which is illustrated in a partial sectional view in  FIGS. 2-6 , further includes a lid  20  made in a single piece of plastic material, such as polypropylene, comprising a base portion  21  which carries a peripheral portion  22  presenting a generally cylindrical outer face  22   a  provided with a circumferential cradle  23 , whose cross section is in the form of a concave arc turned radially outwardly and which is dimensioned to be fitted and axially retained against the closure seat S when the lid  20  is seated on the upper opening A of the can. The lid  20  further comprises an annular portion  24  projecting radially outwardly from the peripheral portion  22  and to be seated onto the annular upper wall  12  upon closure of the tubular body  10  by the lid  20 . 
     In the illustrated constructions, the cylindrical outer face  22   a  of the peripheral portion  22  of the lid  20  incorporates a circumferential projection  23   a  which defines, superiorly and jointly with the cylindrical outer face  22   a , the circumferential cradle  23  presenting a cross section in the form of a concave arc. Nevertheless, it should be understood that the circumferential cradle  23  can be constructed in different shapes such as, for example, in the form of an outer circumferential groove provided in the generally cylindrical outer face  22   a  of the peripheral portion  22  of the lid  20  and presenting its cross section in the form of a concave arc turned radially outwardly. 
       FIGS. 1-6  illustrate a lid  20  made of plastic material and with its annular portion  24  peripherally incorporating, by means of breakable bridges  26 , a seal portion  25  which comprises a skirt  25   a  to be generally tightly seated around the tubular body  10 , under the double-seam  13 , so as to remain axially retained under the latter or under any other deformation defined in the region of the upper edge  11   a  of the side wall  11  of the tubular body  10 , said seal portion  25  further comprising an upper ring  25   b  disposed over an outermost portion of the annular upper wall  12  of the tubular body  10  of the can and internally incorporating the breakable axial bridges  26 . The breakable bridges  26  are disposed so as to unite, in angularly spaced apart points, an inner edge  25   g  of the upper ring  25   b  and a peripheral outer edge of the annular portion  24  of the lid  20 . 
     The breakable bridges  26  are ruptured when submitted to a certain traction force for separating the seal portion  25  from the annular portion  24  upon the first opening of the lid  20 . 
     In the construction of the exemplary plastic lid, the seal portion  25  presents an interruption  25   c  in its circumferential extension and which extends along at least part of the height of the skirt  25   a , said interruption  25   c  defining a certain circumferential spacing between respective confronting edges of the skirt  25   a , on both sides of the interruption  25   c . The annular portion  24  incorporates a grip tab  27  projecting axially upwardly, radially outwardly and also axially downwardly through said interruption  25   c  of the seal portion  25 , for example, remaining substantially leveled with the skirt  25   a , the grip tab  27  being manually operable only when part of the seal portion  25  is broken. 
     In the illustrated construction, the skirt  25  incorporates the ends of a seal bridge  25   d , circumferentially extending over both the interruption  25   c  of the seal portion  25  and the grip tab  27 . The seal bridge  25   d  presents a first end  25   e , which is incorporated to the skirt  25   a  by connecting means  25   f  to be broken when said first end  25   e  is forced away from the skirt  25   a , for example, by being radially outwardly pulled to liberate the manual access to the grip tab  27 . 
     The provision of the grip tab  27  allows the base portion  21  to be easily removed from its seating condition on the closure seat S, as well as a controlled and progressive opening of the can, first in the region adjacent to the grip tab  27  and then in the remaining part of the seat, preventing the stored product from being inadvertently pulled outwardly from the can. 
     According to the present invention the grip tab  27  can present either a solid form or at least a partially hollow form, defining a handle, as in the illustrated construction. 
     It should be understood that the grip tab  27  may be solid and formed from a respective portion of the skirt  25   a , remaining substantially leveled with the latter and maintaining a gap  29  therefrom. 
     As illustrated, the skirt  25   a  may incorporate an inner circumferential projection  25   h  axially spaced from the peripheral edge of the annular portion  24  and dimensioned to be seated and axially locked under the double-seam  13  in the upper end of the tubular body  10  and around the latter. 
     According to the closure arrangement object of the present invention, one or both parts defined by the annular upper wall  12  of the tubular body  10  and by the annular portion  24  of the lid  20  carries an annular gasket  30  that is disposed and dimensioned to be pressed by the other of said parts upon closure of the lid, in order to define a respective annular sealing region between the lid  20  and the tubular body  10 . 
     In the construction illustrated in  FIGS. 2 ,  3  and  4 , the annular gasket  30  is affixed onto the annular upper wall  12  of the tubular body  10 , so as to remain in a radially external positioning in relation to the closure seat S. In  FIG. 2 , there is illustrated an annular gasket  30  directly affixed onto the upper face of the annular upper wall  12 . In a constructive form, the annular gasket  30  may be made of a suitable polymeric resin, such as plastisol, which is melted and molded directly onto the annular upper wall of the tubular body  10 . 
     It should be understood that the annular gasket  30  may be formed of different materials compatible with the products to be packaged and which present a certain compressibility, in order to guarantee the formation of a second sealing region, besides that one defined by the seating of the peripheral portion  22  of the lid  20  against the closure seat S. 
     Thus, upon closure of the lid  20 , its peripheral portion  22  has the circumferential cradle  23  seated against the closure seat S of the tubular body  10 , guaranteeing the formation of a first sealing region, which also operates as an axial retention region for the lid  20  seated on the annular upper wall  12  of the tubular body  10 . In this closed condition of the lid  20 , the annular gasket  30  is axially pressed, in order to guarantee the formation of a respective or second sealing region, which is sufficiently tight to guarantee the tightness of the interior of the can for long periods of storage, as those required for certain food products, particularly when they are intended to be exported. 
       FIG. 3  illustrates a constructive embodiment in which the annular portion  24  of the lid  20  incorporates two circumferential ribs  28  that are configured and dimensioned to press the annular gasket  30  affixed to the annular upper wall  12  of the tubular body  10 , upon closure of the lid  20 , guaranteeing a more intense deformation of the annular gasket  30  and a more reliable sealing. It should be understood that the annular portion  24  of the lid  20  can incorporate only one circumferential rib  28  or more than two, or also no circumferential ribs  28  at all, as illustrated in  FIGS. 2 ,  4 ,  5 ,  7  and  8 . 
       FIG. 4  illustrates a construction in which the annular gasket  30  is formed or otherwise attached in a circumferential recess  19  provided on the annular upper wall  12  of the tubular body  10 , the annular gasket  30  being generally dimensioned to axially project slightly outwardly from the circumferential recess  19 , to be pressed by the annular portion  24  of the lid  20 . The circumferential recess  19  is preferably dimensioned to better limit, with its radially inner and outer walls, the expansion of the annular gasket  30  upon its application, in a melted state, directly to the annular upper wall  12  of the tubular body  10 . 
       FIGS. 5-6  illustrate constructions in which the annular gasket  30  is attached under the annular portion  24  of the lid  20 , to be pressed against the annular upper wall  12  of the tubular body  10 , in an inverted position in relation to that illustrated in  FIGS. 2 ,  3  and  4 . 
     In  FIG. 5 , the annular gasket  30  is affixed into a circumferential recess  29  provided in the annular portion  24  of the lid  20 , said annular gasket  30  axially projecting slightly outwardly from said circumferential recess  29 , to be pressed by the annular upper wall  12  of the tubular body  10  upon closure of the lid  20 . The dimensioning of the circumferential recess  29  must be made in such a way as to contain the radial expansion of the annular gasket  30  when it is molded on the annular portion  24  of the lid  20  in an inverted position. 
       FIG. 6  illustrates a construction in which the annular gasket  30  is affixed to the annular portion  24  of the lid  20  to be pressed by a circumferential rib  18  defined by deformation of the annular upper wall  12  of the tubular body  10 . As discussed above regarding the circumferential rib  28  of the lid  20 , an annular upper wall  12  of the tubular body  10  may incorporate more than one circumferential rib  18 . 
       FIGS. 7 ,  7   a ,  8  and  8   a  illustrate a constructive variant in which the annular upper wall  12  of the tubular body  10  is defined by a radial circumferential rib  16  formed by a recess defined by deformation of the side wall  11  of the tubular body  10 , said radial circumferential rib  16  projecting to the interior of the tubular body  10 , under the upper edge  11   a  of the side wall  11 . 
       FIG. 7  illustrates an embodiment in which the annular gasket  30  is attached onto the annular upper wall  12  of the tubular body  10  or, more precisely, onto the radial circumferential rib  16  which defines the annular upper wall  12 , the lid  20  being made of plastic or sheet metal and presenting the same base portion  21 , peripheral portion  22  and annular portion  24  already described in relation to the plastic lid embodiments illustrated in  FIGS. 1-6 . In this construction, the annular portion  24  of the lid  20 , upon closure of the latter, presses the annular gasket  30 , defining a respective sealing region, apart from that defined by the seating of the circumferential cradle  23  of the lid  20  on the closure seat S, as already described above regarding the embodiments of  FIGS. 1-6 . 
     As it can be noted, the radial circumferential rib  16  presents an inner edge  12   a  configured to define the upper opening “A” of the can and the closure seat “S”, in the form of a preferably circular convex arc, against which is seated and retained the circumferential cradle  23  having its cross section in the form of a concave arc and provided in the peripheral portion  22  of the lid  20 , as described in relation to the embodiments illustrated in  FIGS. 1 to 6 . The radial circumferential rib  16  may present a cross section having any shape adequate to define the closure seat S. In  FIGS. 7 and 7   a , the radial circumferential rib  16  presents a cross section in the form of a horizontal “V”, whereas in  FIGS. 8 and 8   a  the cross section takes the form of a horizontal “U”.  FIG. 7   a  illustrates a closure arrangement similar to that of  FIG. 7 , although having the annular portion  24  of the sheet metal lid  20  deformed to incorporate at least one circumferential rib  28  turned downwardly and dimensioned to press the annular gasket  30 , as described in relation to the arrangement illustrated in  FIG. 3 . 
     As it can be seen in the construction illustrated in  FIG. 7   a , the inner edge  12   a  of the annular upper wall  12 , defined by the radial circumferential rib  16 , is configured to define not only the closure seat S in the form of a convex arc, but also an upper circumferential projection  12   b  projecting upwardly from the annular upper wall  12  of the tubular body  10 , to define a barrier against the undue inward radial expansion of the material of the annular gasket  30  when the latter is molded directly onto said annular upper wall  12 , preventing the still melted material of the annular gasket  30  from flowing to the interior of the tubular body  10  through the closure seat S. It should be understood that the upper circumferential projection  12   b  need not be obligatorily formed close to the inner edge  12   a  of the radial circumferential rib  16 . It may be defined in other radially outermost regions of the upper wall  12 , as it occurs in the arrangement illustrated in  FIG. 4 , in which the upper circumferential projection  12   b  can be defined by the radially inner wall of the circumferential recess  19 . However, it should be understood that, besides the circumferential recess  19 , the annular upper wall  12  may be provided with an upper circumferential projection  12   b  disposed radially spaced from the circumferential recess  19  to operate as an additional barrier against the radial inward expansion of the material of the annular gasket  30  when the latter is directly molded on the annular upper wall  12  of the tubular body  10 . 
     As illustrated in  FIG. 8 , the lid  20 , generally made of plastic material, can have its annular portion  24  peripherally incorporating, by means of breakable bridges  26 , a seal portion  25  with a construction similar to that described for the lid illustrated in  FIGS. 1-6 , but taking into consideration that the skirt  25   a  is shaped to provide a step  25 × to be seated under the end edge  11   a  of the side wall  11  of the tubular body  10 , which end edge  11   a  may take the form of an outer curl operating as a structural element for the tubular body  10 , as well as an ascending axial stop for the skirt  25   a  of the seal portion  25 . 
       FIG. 8   a  illustrates a closure arrangement similar to that of  FIG. 8 , but having an upper wall  12  inferiorly incorporating at least one circumferential rib  18  dimensioned to press an annular gasket  30 , upon closure of the lid  20 , as described in relation to  FIG. 6 . 
     As illustrated in the arrangement of  FIG. 7   a , the arrangement of  FIG. 8   a  has the inner edge  12   a  of the radial circumferential rib  16  configured to define, besides the closure seat S in the form of a convex arc, an upper circumferential projection  12   b  projecting upwardly from the annular upper wall  12  of the tubular body  10 , to define a barrier against the undesired radial expansion, to the closure seat “S”, of the material of the annular gasket  30 , when the latter is applied onto the annular upper wall  12  of the tubular body  10 . 
     It should be understood that the circumferential rib  28  of the annular portion  24  of the lid  20 , as illustrated in  FIGS. 7   a  and  9 , may be substituted by one or more circumferential ribs superiorly incorporated to the annular upper wall  12  of the tubular body  10 , as illustrated in  FIG. 6  of the enclosed drawings, to press an annular gasket  30  attached under the annular portion  24  of the lid  20 . 
       FIG. 9  illustrates a closure arrangement of the type shown in  FIGS. 8 and 8   a  and in which the upper edge  11   a  of the side wall  11  of the tubular body  10  is outwardly, downwardly and inwardly bent to define a tubular rib  17  externally incorporated to the upper edge  11   a  of the side wall  11  and extending downwardly, beyond the radial circumferential rib  16 , covering the recess that forms the latter. In  FIG. 9 , q the annular portion  24  of the lid  20  inferiorly incorporates at least one circumferential rib  28  dimensioned to press the annular gasket  30 , upon closure of the lid. 
     According to the illustrated construction, the tubular rib  11  presents a free lower end portion  17   a  that is inwardly and upwardly bent and disposed adjacent to the side wall  11  of the tubular body  10 , below the radial circumferential rib  16 . The tubular rib  17  is generally oblong in the direction of the can axis, presenting a median extension  17   b  substantially parallel to the side wall  11  of the tubular body  10 , in the region in which the radial circumferential rib  16  is incorporated. 
     In the constructions illustrated in  FIGS. 7 ,  7   a ,  8  and  8   a , the peripheral portion  22  of the lid  20  externally carries a circumferential cradle  23  having its cross section in the form of a concave arc, to be fitted and axially retained against the closure seat S, as already described above in relation to  FIGS. 2-6 . 
     While only some embodiments of the present invention have been described and illustrated herein, it should be understood that alterations can be made in the form and physical arrangement of the elements, without departing from the constructive concept defined in the claims accompanying the present specification.