Patent Publication Number: US-6981299-B2

Title: Closure device

Description:
FIELD OF THE INVENTION 
   The present invention relates generally to closure devices and, more particularly, to a slider having shoulders of differing lengths. The invention is particularly well suited for fastening flexible storage containers, including plastic bags. 
   BACKGROUND OF THE INVENTION 
   The use of closure devices for fastening storage containers, including plastic bags, is generally known. Furthermore, the manufacture of closure devices made of plastic materials is generally known to those skilled in the art, as demonstrated by the numerous patents in this area. 
   A particularly well-known use for closure devices is in connection with flexible storage containers, such as plastic bags. In some instances, the closure device and the associated container are formed from thermoplastic materials, and the closure device and the sidewalls of the container are integrally formed by extrusion as a single piece. Alternatively, the closure device and sidewalls of the container may be formed as separate pieces and then connected by heat sealing or any other suitable connecting process. In either event, such closure devices are particularly useful in providing a closure means for retaining matter within the bag. 
   Conventional closure devices typically utilize mating fastening strips or closure elements, which are used to selectively seal the bag. A slider may be provided for use in opening and closing the fastening strips. Some of these sliders include a separator. When the slider is moved in the appropriate direction, the separator divides the fastening strips and opens the bag. 
   The slider may include shoulders disposed along the bottom of the slider that engage the fastening strips and prevent the slider from being removed from the fastening strips. However, if enough force is applied to the slider in the vertical direction, the sides of the slider may flex outwards allowing the slider to be removed from the fastening strips. 
   SUMMARY OF THE INVENTION 
   According to the teachings of the present invention, the closure device includes interlocking fastening strips. The closure also includes a slider slidably disposed on the interlocking fastening strips for facilitating the occlusion and deocclusion of the fastening strips when moved towards first and second ends of the fastening strips. The slider includes a shoulder with a short length and a shoulder with a long length. The short and long length shoulders are disposed across from each other along the bottom edge of the slider. The longer shoulders are designed to remain engaged to the fastening strips if sufficient force has been applied to the slider to flex the sides of the slider. 
   These and other objects, features, and advantages of the present invention will become more readily apparent upon reading the following detailed description of exemplified embodiments and upon reference to the accompanying drawings herein. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a container according to the present invention in the form of a plastic bag; 
       FIG. 2  is a fragmentary top view of the container in  FIG. 1 ; 
       FIG. 3  is a top view of an embodiment of a slider; 
       FIG. 4  is a front view of the slider in  FIG. 3 ; 
       FIG. 5  is a right side view of the slider in  FIG. 3 ; 
       FIG. 6  is a left side view of the slider in  FIG. 3 ; 
       FIG. 7  is a rear view of the slider above the fastening strips; 
       FIG. 8  is a rear view of the slider partially on the fastening strips; 
       FIG. 9  is a rear view of the slider attached to the fastening strips; 
       FIG. 10  is a top view of another embodiment of a slider; 
       FIG. 11  is a rear view of the fastening strips; 
       FIG. 12  is a rear view of another embodiment of fastening strips; 
       FIG. 13  is a rear view of another embodiment; and 
       FIG. 14  is a rear view of another embodiment. 
     While the present invention will be described and disclosed in connection with certain embodiments and procedures, the intent is not to limit the present invention to these embodiments and procedures. 
   

   DESCRIPTION OF THE EMBODIMENTS 
     FIG. 1  illustrates an embodiment of a container in the form of a plastic bag  120  having a sealable closure device  121 . The bag  120  includes a first sidewall  122  and a second sidewall  123  joined at seams  125 ,  126  to define a compartment accessible through the open top end but sealable by means of the closure device  121 . The closure device  121  includes first and second fastening strips  130 ,  131  and a slider  132 . 
   The fastening strips  130 ,  131  and the slider  132  have a longitudinal X axis  102 , a transverse Y axis  104  and a vertical Z axis  106 . The transverse Y axis  104  is perpendicular to the longitudinal X axis  102 . The vertical Z axis  106  is perpendicular to the longitudinal X axis  102  and the vertical Z axis  106  is perpendicular to the transverse Y axis  104 . 
   The fastening strips  130 ,  131  are adapted to be interlocked between a first end and a second end. The slider  132  is mounted onto the fastening strips  130 ,  131  so that the slider  132  is restrained from being removed from the fastening strips  130 ,  131  but free to slide along the X axis  102 . The slider  132  engages the fastening strips  130 ,  131  so that when the slider  132  moves in an occlusion direction  114 , the fastening strips  130 ,  131  interlock and the bag  120  is sealed, and when the slider  132  moves in a deocclusion direction  116 , the fastening strips  130 ,  131  separate and the bag  120  is open. 
     FIG. 2  illustrates a partial top view of the closure device in FIG.  1  and depicts the fastening strips  130 ,  131  and slider  132 . The slider includes first and second side portions  142 ,  144  attached to a top portion  140 . The first side portion  142  includes first and second front shoulders  150 ,  152 . The first side portion  142  additionally includes first and second rear shoulders  160 ,  162 . Similarly, the second side portion  144  includes first and second front shoulders  154 ,  156  and first and second rear shoulders  164 ,  166 . 
   Referring to  FIGS. 3-6 , the first front shoulders  150 ,  154  are disposed perpendicular to the side portions  142 ,  144  and are placed across from each other. The second front shoulders  152 ,  156  are disposed parallel and in close proximity to the first front shoulders  150 ,  154  and are likewise placed across from each other. Similarly, the first rear shoulders  160 ,  164  are disposed perpendicular to the side portions  142 ,  144  and are placed across from each other. The second rear shoulders  162 ,  166  are disposed parallel and in close proximity to the first rear shoulders  160 ,  164  and are likewise placed across from each other. 
   The shoulders are such that some of the shoulders have a longer length than other shoulders. Additionally, the shoulders may be placed such that if one shoulder is of a long length, then the shoulder across from it is of a short length. In addition, if a shoulder is of a long length, then the shoulder next to that shoulder may be of a short length. Conversely, if the shoulder is of a short length, than the shoulders next to and across from it may be of a long length. This situation causes portions of the fastening strips to bend around the shoulders, which further makes it difficult to remove the slider from the fastening strips. For example, as best illustrated in  FIG. 3 , shoulder  150  is of a long length. The shoulder across from it, shoulder  154 , and the shoulder disposed next to it, shoulder  152 , are both of a short length. 
     FIG. 4  illustrates a front view of the slider  132 . The top portion  140  of the slider includes a separator  133 . The separator  133  may be generally triangular in shape. The separator  133  facilitates the deocclusion of the fastening strips. The first side portion  142  includes a first occlusion member  146 . Similarly, the second side portion  144  includes a second occlusion member  148 . The first and second occlusion members  146 ,  148  facilitate occlusion of the fastening strips by applying pressure to the fastening strips. 
     FIGS. 7-9  sequentially illustrate the attachment of the slider  132  made in accordance with the present invention onto the fastening strips  130 ,  131  in the vertical Z axis  106 . Although the following description will be limited to the slider components illustrated in the respective view described, it will be appreciated that the other slider components will function in a similar manner. For example, the first front shoulders  150 ,  154  of the slider  132  will operate in the same fashion as the second rear shoulders  162 ,  166  of the slider  132  during attachment of the slider  132  onto the fastening strips  130 ,  131 . 
     FIG. 7  depicts occluded fastening strips  130 ,  131  and a slider  132  having first rear shoulders  160 ,  164  and second rear shoulders  162 ,  166  in a relaxed position. The occluded fastening strips  130 ,  131  are immediately below the slider  132 . Referring to  FIG. 8 , the slider  132  is moved in the vertical Z axis  106  towards the fastening strips  130 ,  131 . The fastening strips engage the rear shoulders  160 ,  162 ,  164 ,  166  and deflect the side portions  142 ,  144  outwardly in the transverse Y axis  104 . The fastening strips  130 ,  131  are guided into the slider  132  by the occlusion members  146 ,  148 . 
   As shown in  FIG. 9 , upon further movement of the fastening strips  130 ,  131  toward the slider  132  in the vertical Z axis  106 , the rear shoulders  160 ,  162 ,  164 ,  166 , and the side portions  142 ,  144  retract back to their relaxed position. In addition, the separator  133  is forced between the flanges of the occluded fastening strips  130 ,  131 . 
   During use of the slider  132  on the fastening strips  130 ,  131 , the user may exert an upward force  180  in the Z axis  106  on the slider  132  as shown in FIG.  9 . The upward force will cause the shoulders to engage the fastening strips. The following description will be limited to shoulders  160 ,  162 ,  164 ,  166 . Thus, the shoulders  160 ,  162 ,  164 ,  166  would engage the ribs  182 ,  184 . If the user continues to apply the upward force  180 , the force would be transmitted through the shoulders  160 ,  162 ,  164 ,  166  to the first and second side portions  142 ,  144 . 
   The first and second side portions  142 ,  144  would begin to deflect outward in directions  180 ,  188 . However, the shoulder  162  is longer than shoulder  166 . Thus, the force required to move the shoulder  162  past the fastening strip  130  would be greater than the force required to move the shoulder  166  past the fastening strip  131  due to the additional distance to be traveled by the shoulder  162 . Similarly, shoulders  160 ,  164  would operate in a similar manner. Therefore, more force is required to remove the slider  132  with one long shoulder opposite one short shoulder than one short shoulder opposite a second short shoulder. The other shoulders  150 ,  152 ,  154 ,  156  would operate in a similar manner. 
     FIG. 10  illustrates another embodiment of a slider  232 . The slider  232  includes a top portion  240 , a first side portion  242  and a second side portion  244 . The side portions  242 ,  244  include first front shoulders  250 ,  254  and first rear shoulders  260 ,  264 . The shoulders  250 ,  264  are of a long length and the shoulders  254 ,  260  are of a short length. 
   In keeping with a general aspect of the present invention and as will be described in greater detail below, the interlocking fastening strips of the present invention may be of various types or forms. 
   As shown in  FIG. 11 , the fastening strips may be U-channel fastening strips as described in U.S. Pat. No. 4,829,641. U-channel fastening strips include a first fastening strip  330  with a first closure element  336  and a second fastening strip  331  with a second closure element  334 . The first closure element  336  engages the second closure element  334 . The first fastening strip  330  may include a flange  363  disposed at the upper end of the first fastening strip  330  and a rib  367  disposed at the lower end of the first fastening strip  330 . The fist fastening strip  330  may include a flange portion  369 . Likewise, the second fastening strip  331  may include a flange  353  disposed at the upper end of the second fastening strip  331  and a rib  357  disposed at the lower end of the second fastening strip  331 . The second fastening strip  331  may include a flange portion  359 . The side walls  322 ,  323  of the plastic bag may be attached to the fastening strips  330 ,  331  by conventional manufacturing techniques. 
   The second closure element  334  includes a base portion  338  having a pair of spaced-apart parallely disposed webs  340 ,  341 , extending from the base portion  338 . The base and the webs form a U-channel closure element. The webs  340 , include hook closure portions  342 ,  344  extending from the webs  340 ,  341  respectively, and facing towards each other. The hook closure portions  342 ,  344  include guide surfaces  346 ,  347  which serve to guide the hook closure portions  342 ,  344  for occluding with the hook closure portions  352 ,  354  of the first closure element  336 . 
   The first closure element  336  includes a base portion  348  including a pair of spaced-apart, parallely disposed webs  350 ,  351  extending from the base portion  348 . The base and the webs form a U-channel closure element. The webs  350 ,  351  include hook closure portions  352 ,  354  extending from the webs  350 ,  351  respectively and facing away from each other. The hook closure portions  352 ,  354  include guide surfaces  345 ,  355 , which generally serve to guide the hook closure portions  352 ,  354  for occlusion with the hook closure portions  342 ,  344  of the second closure element  334 . The guide surfaces  345 ,  355  may also have a rounded crown surface. 
   When the slider is moved in the occlusion direction, the separator deoccludes the fastening strips  330 ,  331  as shown in FIG.  11 . Referring to  FIG. 11 , the closure elements  334 ,  336  are deoccluded and specifically, the upper hook portions  342 ,  352  and the lower hook portions  344 ,  354  are deoccluded. 
   The interlocking fastening strips may comprise “arrowhead-type” or “rib and groove” fastening strips as shown in FIG.  12  and as described in U.S. Pat. No. 3,806,998. The rib element  405  interlocks with the groove element  407 . The rib element  405  is of generally arrow-shape in transverse cross section including a head  410  comprising interlock shoulder hook portions  411  and  412  generally convergently related to provide a cam ridge  413  generally aligned with a stem flange  414  by which the head is connected in spaced relation with respect to the supporting flange portion  408 . (U.S. Pat. No. 3,806,998, Col. 2, lines 16-23). At their surfaces nearest the connecting stem flange  414 , the shoulder portions  411  and  412  define reentrant angles therewith providing interlock hooks engageable with interlock hook flanges  415  and  417  respectively of the groove element  407 . (U.S. Pat. No. 3,806,998, Col. 2, lines 23-28). Said hook flanges generally converge toward one another and are spread open to receive the head  410  therebetween when said head is pressed into said groove element  407  until the head is fully received in a groove  418  of said groove element  407  generally complementary to the head and within which the head is interlocked by interengagement of the head shoulder hook portions  411  and  412  and the groove hook flanges  415  and  417 . (U.S. Pat. 3,806,998, Col. 2, lines 28-36). Through this arrangement, as indicated, the head and groove elements  405  and  407  are adapted to be interlockingly engaged by being pressed together and to be separated when forcably pulled apart, as by means of a generally U-shaped slider  419 . (U.S. Pat. No. 3,806,998, Col. 2, lines 36-41). 
   The slider  419  includes a flat back plate  420  adapted to run along free edges  421  on the upper ends of the sections of the flange portions  408  and  409  as shown in the drawing. (U.S. Pat. No. 3,806,998, Col. 2, lines 41-46). Integrally formed with the back plate  420  and extending in the same direction (downwardly as shown) therefrom are respective coextensive side walls  422  with an intermediate spreader finger  423  extending in the same direction as the side walls at one end of the slider. (U.S. Pat. No. 3,806,998, Col. 2, lines 46-51). The side walls  422  are in the form of panels which are laterally divergent from a narrower end of the slider. (U.S. Pat. No. 3,806,998, Col. 2, lines 51-55). The slider walls  422  are each provided with an inwardly projecting shoulder structure  424  flange adapted to engage respective shoulder ribs  425  and  427  on respectively outer sides of the lower section of the flange portions  408  and  409 . (U.S. Pat. No. 3,806,998, Col. 2, line 66 to Co. 3, line 3). 
   Additionally, the interlocking fastening strips may comprise “profile” fastening strips, as shown in FIG.  13 . and described in U.S. Pat. No. 5,664,299. The first profile  516  has at least an uppermost closure element  516   a  and a bottommost closure element  516   b . (U.S. Pat. No. 5,664,299, Col. 3, lines 25-27). The closure elements  516   a  and  516   b  project laterally from the inner surface of strip  514 . (U.S. Pat. No. 5,664,299, Col. 3, lines 27-28). Likewise, the second profile  517  has at least an uppermost closure element  517   a  and a bottommost closure element  517   b . (U.S. Pat. No. 5,664,299, Col. 3, lines 28-30). The closure elements  517   a  and  517   b  project laterally from the inner surface of strip  515 . (U.S. Pat. No. 5,664,299, Col. 3, lines 30-32). When the bag is closed, the closure elements of profile  516  interlock with the corresponding closure elements of profile  517 . (U.S. Pat. No. 5,664,299, Col. 3, lines 32-34). Closure elements  516   a ,  516   b ,  517   a  and  517   b  have hooks on the ends of the closure elements, so that the profiles remain interlocked when the bag is closed, thereby forming a seal. (U.S. Pat. No. 5,664,299, Col. 3, lines 34-37). 
   The straddling slider  510  comprises an inverted U-shaped member having a top  520  for moving along the top edges of the strips  514  and  515 . (U.S. Pat. No. 5,664,299, Col. 4, lines 1-3). The slider  510  has side walls  521  and  522  depending from the top  520 . (U.S. Pat. No. 5,664,299, Col. 4, lines 3-4). A separating leg  523  depends from the top  520  between the side walls  521  and  522  and is located between the uppermost closure elements  516   a  and  517   a  of profiles  516  and  517 . (U.S. Pat. No. 5,664,299, Col. 4, lines 26-30). The fastening assembly includes ridges  525  on the outer surfaces of the fastening strips  514  and  515 , and shoulders  521   b  and  522   b  on the side walls of the slider. (U.S. Pat. No. 5,664,299, Col. 4, lines 62-65) . The shoulders act as means for maintaining the slider in straddling relation with the fastening strips by grasping the lower surfaces of the ridges  525 . (U.S. Pat. No. 5,664,299, Col. 5, lines 4-7). 
   Also, the interlocking fastening strips may be “rolling action” fastening strips as shown in FIG.  14  and described in U.S. Pat. No. 5,007,143. The strips  614  and  615  include profiled tracks  618  and  619  extending along the length thereof parallel to the rib and groove elements  616  and  617  and the rib and groove elements  616 ,  617  have complimentary cross-sectional shapes such that they are closed by pressing the bottom of the elements together first and then rolling the elements to a closed position toward the top thereof. (U.S. Pat. No. 5,007,143, Col. 4, line 62 to Col. 5, line 1). The rib element  616  is hook shaped and projects from the inner face of strip  614 . (U.S. Pat. No. 5,007,143, Col. 5, lines 1-3). The groove element  617  includes a lower hook-shaped projection  617   a  and a relatively straight projection  617   b  which extend from the inner face of strip  615 . (U.S. Pat. No. 5,007,143, Col. 5, lines 3-6). The profiled tracks  618  and  619  are inclined inwardly toward each other from their respective strips  614  and  615 . (U.S. Pat. No. 5,007,143, Col. 5, lines 6-8). 
   The straddling slider  610  comprises an inverted U-shaped plastic member having a back  620  for moving along the top edges of the tracks  618  and  619  with side walls  621  and  622  depending therefrom for cooperating with the tracks and extending from an opening end of the slider to a closing end. (U.S. Pat. No. 5,007,143, Col. 5, lines 26-31). A separator finger  623  depends from the back  620  between the side walls  621  and  622  and is inserted between the inclined tracks  618  and  619 . (U.S. Pat. No. 5,007,143, Col. 5, lines 34-36). The slider  610  has shoulders  621   a  and  622   a  projecting inwardly from the depending side walls  621  and  622  which are shaped throughout the length thereof for cooperation with the depending separator finger  623  in creating the rolling action in opening and closing the reclosable interlocking rib and groove profile elements  616  and  617 . (U.S. Pat. No. 5,007,143, Col. 5, lines 43-49). 
   Although several interlocking fastening strip embodiments have been specifically described and illustrated herein, it will be readily appreciated by those skilled in the art that other kinds, types, or forms of fastening strips may alternatively be used without departing from the scope or spirit of the present invention. 
   The interlocking fastening strips may be manufactured by extrusion through a die. The interlocking fastening strips may be formed from any suitable thermoplastic material including, for example, polyethylene, polypropylene, nylon, or the like, or from a combination thereof. Thus, resins or mixtures of resins such as high density polyethylene, medium density polyethylene, and low density polyethylene may be employed to prepare the interlocking fastening strips. For example, the fastening strips may be made from low density polyethylene. 
   When the fastening strips are used in a sealable bag, the fastening strips and the films that form the body of the bag may be conveniently manufactured from heat sealable material. In this way, the bag may be economically formed by using an aforementioned thermoplastic material and by heat sealing the fastening strips to the bag. For example, the bag may be made from a mixture of high pressure, low density polyethylene and linear, low density polyethylene. 
   The fastening strips may be manufactured by extrusion or other known methods. For example, the closure device may be manufactured as individual fastening strips for later attachment to the bag or may be manufactured integrally with the bag. In addition, the fastening strips may be manufactured with or without flange portions on one or both of the fastening strips depending upon the intended use of the fastening strips or expected additional manufacturing operations. 
   The fastening strips can be manufactured in a variety of forms to suit the intended use. The fastening strips may be integrally formed on the opposing sidewalls of the container or bag, or connected to the container by the use of any of many known methods. For example, a thermoelectric device may be applied to a film in contact with the flange portion of the fastening strips or the thermoelectric device may be applied to a film in contact with the base portion of fastening strips having no flange portion, to cause a transfer of heat through the film to produce melting at the interface of the film and a flange portion or base portion of the fastening strips. Suitable thermoelectric devices include heated rotary discs, traveling heater bands, resistance-heated slide wires, and the like. The connection between the film and the fastening strips may also be established by the use of hot melt adhesives, hot jets of air to the interface, ultrasonic heating, or other known methods. The bonding of the fastening strips to the film stock may be carried out either before or after the film is U-folded to form the bag. In any event, such bonding is done prior to side sealing the bag at the edges by conventional thermal cutting. In addition, the first and second fastening strips may be positioned on opposite sides of the film. Such an embodiment would be suited for wrapping an object or a collection of objects such as wires. The first and second fastening strips should usually be positioned on the film in a generally parallel relationship with respect to each other, although this will depend on the intended use. 
   The slider may be multiple parts and snapped together. In addition, the slider may be made from multiple parts and fused or welded together. The slider may also be a one piece construction. The slider can be colored, opaque, translucent or transparent. The slider may be injection molded or made by any other method. The slider may be molded from any suitable plastic material, such as, nylon, polypropylene, polystyrene, acetal, toughened acetal, polyketone, polybutylene terrephthalate, high density polyethylene, polycarbonate or ABS (acrylonitrile-butadiene-styrene). 
   From the foregoing it will be understood that modifications and variations may be effectuated to the disclosed structures—particularly in light of the foregoing teachings—without departing from the scope or spirit of the present invention. As such, no limitation with respect to the specific embodiments described and illustrated herein is intended or should be inferred. In addition, all references and copending applications cited herein are hereby incorporated by reference in their entireties.