Abstract:
A reclosable plastic bag includes a pouch and first and second extruded fastener members heat sealed or welded thereto. One of the fastener members is provided with a plurality of standoffs in a flange area providing spaces between it and the opposing flange of the opposing fastening member to permit heat sealing or welding of the fastener members to the respective sidewalls of the pouch without inadvertently heat sealing or welding the flanges of the opposing fastener members together.

Description:
This application is a continuation of application Ser. No. 09/384,883 filed Aug. 27, 1999 now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed to a reclosable plastic bag having an extruded fastener and to a method for forming such reclosable bag. 
     Reclosable plastic bags having extruded fasteners are well known in the art. Frequently the pouch portion is manufactured in one manufacturing operation and the extruded fasteners, manufactured in a different manufacturing operation, are adhered or heat sealed in an area adjacent an opening defined by the edge of the pouch. See for example U.S. Pat. Nos. RE 28,969; 3,633,642; 4,430,070; 4,601,694; 4,673,373; 4,736,451 and 5,017,021. Some of these patents, such as U.S. Pat. No. 3,633,642 provide a design in which the interlocking closure mechanism require the same amount of force to disengage the mechanism from the outboard side as from the inboard side. Others, such as U.S. Pat. Nos. 3,347,298; 3,425,469; 4,430,070; and RE 28,969 provide designs which require less force to open when having their outer peripheral edges pulled by a consumer than is required by opening from the inside, for example, from pressure exerted within the closed bag. 
     Some designs of extruded fastener elements are provided with a flange of greater thickness than the film material of the pouch which extend outwardly from the hook and groove toward the open end of the pouch to provide greater strength to the bag for opening than would be provided simply by the mouth-opening marginal portions of the pouch formed from the film material. 
     One method of affixing the extruded fasteners to the pouches utilizes a heat sealing operation for welding the extruded fastener members to the thinner film material. In other instances, adhesive is utilized to effect such connection. 
     In those instances in which the extruded fasteners are provided with flanges, it has been necessary, in heat sealing or welding the flange areas to the film material of the pouch, to utilize a complicated process to prevent the opposing flanges of the cooperating fastener members from becoming inadvertently welded together. Thus, it is efficient to effect the heat sealing of the fastener members to their respective sides of the pouch forming the mouth-opening by simultaneously passing between heated members both of the extruded fastener members, with each fastener member in interfacial engagement with the film at the respective edges of the pouch adjacent the open ends. The fastener members have substantially flat base surfaces opposite the hook and groove profile. The heated elements cause the film to become heat sealed to the flat base surface of each of the respective extruded fastener members. Although those portions of the- extruded fastener members forming the hooks and grooves have sufficient mass to prevent the hooks from becoming welded in the grooves of the opposing fastener member during heat sealing of the film to the base surfaces, the flanges, although substantially thicker than the film, have substantially less mass than the hook and groove portions of the extruded fasteners. As a result, problems can be encountered with the flanges of the opposing fasteners becoming welded together, thereby rendering the bag being formed unusable. 
     According to the present invention, the flange of at least one of the extruded fastener members is provided with one or more outwardly extending standoffs, each of which has an end portion in contact with the opposing flange of the opposing fastener member during the welding operation. The standoff elements provide an air gap between major portions of the opposing flanges and serve to prevent inadvertent welding of the opposing flanges together during the step of heat sealing the extruded fastener members to the respective walls of the bag adjacent the mouth opening. The standoff elements are extruded with the other portions of its extruded fastener forming with such other portions a unitary fastener. 
     Accordingly, it is an object of the present invention to provide a new bag design including an extruded fastener member which may be easily and efficiently assembled. 
     It is further an object of the present invention to provide a method for assembling a bag and extruded fastener member using a heat sealing process. 
     Other objects and advantages of the present invention will become readily apparent to those skilled in the art from the following detailed description of the invention. 
    
    
     IN THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a flexible plastic bag incorporating the features of the present invention. 
     FIG. 2 is an enlarged sectional view showing the mouth end of the plastic bag and showing schematically heating elements aligned with those portions of the extruded fastener elements to be adhered thereto. 
     FIG. 3 is a perspective view of the bag shown in FIG.  1 . 
     FIG. 4 is a view similar to FIG. 1 showing another embodiment of the present invention. 
     FIG. 5 is a view similar to FIG. 2 for the embodiment of FIG.  4 . 
     FIG. 6 is a view similar to FIG. 5 showing a further embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 and 2, there is shown a bag generally designated by the numeral  10  which includes a thin walled plastic pouch  12 , a first extruded fastener member  20  and a second extruded fastener member  30 . The pouch  12 , formed from a sheet of film, and the first and second fastener members  20  and  30  may be one of a variety of plastic materials well known in the art such as low density polyethylene or polypropylene, for example. 
     The pouch  12  has sidewalls  13  and  14  which extend between a gusseted bottom  15  joining the sidewalls  13  and  14  together and an open mouth defined by edges  17  for sidewall  13  and  18  for sidewall  14 . The sidewalls  13  and  14  are joined together at side edges  19  (only one of which is shown in FIG. 3) which extend between the gusseted bottom  15  and the respective edges  17  and  18 . 
     The first fastener member  20  is heat sealed to sidewall  13  and includes (i) a wall  21  extending inwardly toward the sidewall  14  and having a surface facing the gusseted bottom  15 , (ii) a first hook  22  spaced therefrom and cooperating therewith to define a first groove and (iii) a second hook  23  spaced from and having a different cross-sectional configuration than the first hook  22  and cooperating therewith to define a second groove. Extending from the second hook  23  toward the edge  17  of sidewall  13  is a flange  24  which has a thickness on the order of as much as two to three times that of the pouch  12 . For example, the thickness of the pouch  12  may be in the range of 0.0015 inch to 0.010 inch while the thickness of the flange  24  may be in the range of 0.015 inch. The flange  24  extends to an end  25  which preferably is spaced from the edge  17  of the sidewall  13 . The first fastener member  20  has a substantially smooth engagement surface  28  facing and heat sealed or otherwise heat welded to the sidewall  13 . 
     Heat sealed or otherwise heat welded to the other sidewall  14  is the second fastener member  30 . The second fastener member  30  includes a first hook  31  which is sized and shaped to be snugly received in the groove defined by the wall  21  and first hook  22  of the first fastener member  20 . The second fastener member  30  is further provided with a second hook  32  having a different cross-sectional configuration from that of the first hook  31  of the second fastener member  30 . The second hook  32  is sized and shaped to fit in the groove between the first hook  22  and second hook  23  of the first fastener member  20  but is smaller than such groove such that a space is provided between it and the second hook  23  of the first fastener member  20 . 
     Spaced from the second hook  32  is a wall  33  which cooperates with the second hook  32  to defined a groove in which is positioned the second hook  23  of the first fastener member  20 . The groove defined by the second fastener member second hook  32  and wall  33  is larger than the second hook  23  of the first fastener member  20 . 
     Extending outwardly toward the edge  18  of the sidewall  14  is a flange  34  which extends to an end  35  spaced inwardly toward the gusseted bottom  15  from the edge  18 . Extending outwardly from the flange  34  toward the flange  24  is an intermediate standoff  36  spaced from the wall  33  and an outer standoff  37  spaced from the intermediate standoff  36 . 
     As can be seen in FIG. 3, the first and second hooks  31  and  32 , the wall  33  and the standoffs  36  and  37  of the second fastener member  30  extend substantially across the full width of the pouch  12  between the edges  19 . Similarly, the wall  21  and hooks  22  and  23  of the first fastener member  20  extend substantially across the full width of the pouch  12  between the edges  19 . 
     The second fastener member  30  has a substantially smooth engagement surface  38 , a portion of which is heat sealed or otherwise heat welded to the sidewall  14 . 
     Referring to FIG. 2, there is shown schematically a first heating element  40  spaced from the sidewall  13  and extending from a first end  41  aligned with the end  25  of the flange  24  of the first fastener member  20  to a second end  42  aligned with the wall  21  of the first fastener member  20 . The heating element  40  and associated conventional welding or heat apparatus operate to heat seal or weld the first fastener member  20  to the sidewall  13  of the pouch throughout substantially the full breadth from near the end  25  to the wall  21 , which heat seal or weld may be continuous or intermittent. 
     Spaced from the sidewall  14  is a second heating element  45  which extends from a first end  46  aligned near the end  35  of the second fastener member  30  to a second end  47  aligned with the wall  33  of the second fastener member  30 . As a result of heating in only that area, only that portion of the second fastener member  30  near the end  35  and near the wall  33  will be heat sealed or welded to the sidewall  14  and that portion of the second fastener member  30  near the wall  33  and the first hook  31  will not be welded or heat sealed to the sidewall  14 . 
     During the heat sealing operation, the standoffs  36  and  37  will serve to maintain gaps  39  between the flange  24  of the first fastener member  20  and the flange  34  (except for the ends of the standoffs  36  and  37 ) of the second fastener member  30  to prevent the flange  24  from becoming heat sealed to the flange  34 . This is true irrespective of whether the first fastener member  20  is heat sealed or welded to the side wall  13  simultaneously with the heat sealing or welding of the second fastener member  30  to the side wall  14  or is heat sealed or welded at a different time, i.e. consecutively. 
     Referring to FIGS. 4 and 5, there is shown a further embodiment of a reclosable plastic bag  110  having a pouch  112  and a first fastener member  120  engaged to a second fastener member  130 . The pouch  112  has a sidewall  113  to which the first fastener member  120  is heat sealed and a second sidewall  114  to which the second fastener element is heat sealed. 
     The pouch  112  has sidewalls  113  and  114  which extend between a gusseted bottom  115  joining the sidewalls  113  and  114  together and an open mouth defined by edges  117  for sidewall  113  and  118  for sidewall  114 . The sidewalls  113  and  114  are joined together at side edges which extend between the gusseted bottom  115  and the respective edges  117  and  118 . 
     The first fastener member  120  is heat sealed to sidewall  113  and includes (i) a wall  121  extending inwardly toward the sidewall  114  and having a surface facing the gusseted bottom  115 , (ii) a hook  122  spaced therefrom and cooperating therewith to define a first groove and (iii) a second hook  123  spaced from and having a similar cross-sectional configuration as the first hook  122  and cooperating therewith to define a second groove. Extending from the second hook  123  toward the edge  117  of sidewall  113  is a flange  124  which has a thickness substantially greater than that of the pouch  112 . The flange  124  extends to an end  125  which preferably is spaced from the edge  117  of the sidewall  113 . The flange  124  has substantially greater breadth from the second hook  123  to the end  125  than the flange  24  of the embodiment of FIGS. 1 and 2. The first fastener member  120  has a substantially smooth engagement surface  128  facing and heat sealed or otherwise heat welded to the sidewall  113 . 
     Heat sealed or otherwise heat welded to the other sidewall  114  is the second fastener member  130 . The second fastener member  130  includes a first hook  131  which is sized and shaped to be snugly received in the groove defined by the wall  121  and first hook  122  of the first fastener member  120 . The second fastener member  130  is further provided with a second hook  132  having a similar cross-sectional configuration as that of the first hook  131  of the second fastener member  130 . The second hook  132  is sized and shaped to be snugly received in the groove between the first hook  122  and second hook  123  of the first fastener member  120 . 
     Spaced from the second hook  132  is a wall  133  which cooperates with the second hook  132  to defined a groove in which is positioned the second hook  123  of the first fastener member  120 . The groove defined by the second fastener member second hook  132  and wall  133  is similar in size and shape to and snugly receives the second hook  123  of the first fastener member  120 . 
     Extending outwardly toward the edge  118  of the sidewall  114  is a flange  134  which extends to an end  135  spaced inwardly toward the gusseted bottom  115  from the edge  118 . Extending outwardly from the flange  134  toward the flange  124  are a plurality of spaced apart standoffs  136 , the first of which is spaced from the wall  133 . 
     The first and second hooks  131  and  132 , the wall  133  and the standoffs  136  of the second fastener member  130  extend substantially across the full width of the pouch  112  from edge to edge. Similarly, the wall  121  and hooks  122  and  123  of the first fastener member  120  extend substantially across the full width of the pouch  112 . 
     The second fastener member  130  has a substantially smooth engagement surface  138  facing and heat sealed or otherwise heat welded to the sidewall  114 . 
     Referring to FIG. 5, there is shown schematically a first heating element  140  spaced from the sidewall  113  and extending from a first end  141  aligned near the end  125  of the flange  124  of the first fastener member  120  to a second end  142  aligned near the wall  121  of the first fastener member  120 . The heating element  140  and associated conventional welding or heat apparatus operate to heat seal or weld the first fastener member  120  to the sidewall  113  of the pouch throughout substantially the full breadth from near the end  125  to near the wall  121 , continuous or intermittent. 
     Spaced from the sidewall  114  is a second heating element  145  which extends from a first end  146  aligned near the end  135  of the second fastener member  130  to a second end  147  aligned with the wall  133  of the second fastener member  130 . As a result of heating and/or welding in only that area, only that portion of the second fastener member  130  between near the end  135  and the wall  133  will be heat sealed or welded to the sidewall  114  and that portion of the second fastener member  130  between the wall  133  and the first hook  131  will not be welded or heat sealed to the sidewall  114 . During the heat sealing or welding operation, the standoffs  136  will serve to maintain gaps  139  between the flange  124  of the first fastener member  120  and the flange  134  of the second fastener member  130  to prevent the flange  124  from becoming heat sealed or welded to the flange  134 . 
     Referring to FIG. 6, there is shown a bag  210  having a pouch  212  with a sidewall  213  to which is heat sealed or welded a first fastener member  220 , which is identical to the fastener element shown in FIGS. 1 and 2, and a second sidewall  214  to which is heat sealed or welded a second fastener member  230 , which is identical to the fastener member  30  of the embodiment of FIGS. 1 and 2. The difference between the embodiment of FIG.  6  and that of FIGS. 1 and 2 is the extent to which the respective fastener members  220  and  230  are heat sealed or welded to their respective sidewalls  213  and  214 . As can be seen in FIG. 6, the sidewalls  213  and  214  are shown as being spread to a spaced apart position as they would be with the bag  210  filled with product being stored. The fastener members  220  and.  230  are engaged to one another so that the bag  210  is closed. The areas shown in FIG. 6 in which the sidewall  213  is spaced from the surface  228  of the first fastening element  220  and the second sidewall  214  is spaced from the engagement surface  238  of the second fastening element  230  represent the areas in which such sidewalls  213  and  214  are not heat sealed or welded to their respective fastener members  220  and  230 . 
     According to this embodiment of the invention, it is preferred that the sidewall  213  be heat sealed or welded to the first fastener member  220  from substantially near the end  225  throughout a distance of approximately ⅞ of the breadth of the fastener member which is the distance between such end  225  and the wall  221 . 
     It is preferred that the sidewall  214  be adhered to the second fastener member  230  from near its end  235  for a portion or all of the distance between near such end  235  and the wall  233 , but not beyond the wall  233 . It has been found that by locating the extent of the welds or heat seals in this manner, the bag  210  is significantly more difficult to open on the inside/product side and requires more force to open as a result of pressures generated on the inside than the force required to open by a consumer pulling on the portions adjacent to the ends  217  and  218 . 
     Many modifications will become readily apparent to those skilled in the art. For example, if desired, the standoffs could be formed on the flanges of both of the fastener members in staggered relationship to one another. Accordingly, the scope of the present invention should be determined only by the scope of the claims appended hereto.