Abstract:
A semi-rigid flexible film pack for multi-packs, and method for manufacturing same, constructed from a gusseted bag. The invention provides for modifying a gusseted bag, heat sealing the gussets to their respective side walls, loading said gusseted bag with product, and then sealing the open end of the gusseted bag with a single sheet or web. The method of making this package is economical yet provides for a semi-rigid container ideal for use with single-serve pillow bags.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. application Ser. No. 11/756,897 entitled “Method for Making a Semi-Rigid Flexible Film Pack for Multi-Packs” and filed on Jun. 1, 2007. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a semi-rigid flexible film pack that can be used for containing multiple packages of a product and a method for making same. The invention uses standard flexible film pre-made gusseted bags as a starting material. In a preferred embodiment, the gussets on the gusseted bag are heat-sealed to the side walls, product (typically pillow bags containing a snack food) is placed within the gusseted bag, and the open end of the gusseted bag is sealed by application of a single sheet or web of film. 
     2. Description of Related Art 
     The snack food industry typically markets snack foods in flexible film packages referred to as pillow bags due to their shape that is similar to a pillow. These pillow bags are typically made on vertical form, fill, and seal packaging machines. The pillow bags come in a variety of shapes and sizes, anywhere from small single-serve bags of about 6 inches in height and 5 inches in width, to much larger packages in excess of 20 inches in height and 12 inches in width. 
     With the smaller single-serve type pillow bags, it is frequently preferable to market and sell several of these pillow bags as a combined unit. In the prior art, this has typically been accomplished by placing the pillow bags in a rectangular shaped cardboard container having an open top and then sealing the container with a flexible film that encloses the entire cardboard box, including its opening. The advantage of such cardboard box is that the cardboard provides a semi-rigid structure that is somewhat protective of the pillow bags. This prior art solution, however, has several drawbacks. For example, the use of the cardboard box adds to both the expense of producing the combined packaging and to the shipping weight of the combination. Further, several steps are involved in forming the box, filling the box, and enclosing the box with a flexible film. Also, the cardboard material used to construct the box is not transparent. Consequently, the consumer can only observe the contents of the box through the top or sealed end. 
     Another prior art solution is to fill a larger pillow bag with smaller pillow bags. A related solution is to have a flexible film sack that is filled with pillow bags and simply tied at the top. Both of these prior art solutions are less expensive and easier to manufacture than the cardboard box solution described above. However, they do not provide for structural integrity of the overall container, as is accomplished with the cardboard box arrangement. The shape of the stuffed large bag is also not conducive to stacking. 
     Consequently, a need exists for a semi-rigid container that is relatively simple and inexpensive to manufacture, yet also provides some structural rigidity to the overall package. Such container should ideally be roughly rectangular shaped to facilitate stacking and transparent absent graphics placed on the container. 
     SUMMARY OF THE INVENTION 
     The proposed invention uses prior art gusseted bags that are modified and then formed into a semi-rigid package for containing multiple pillow bags or similar articles. The gusseted bag, which is basically a five-sided container having an open end, one bottom (or closed end) wall, four side walls, and two gussets located at two opposed side walls, are common in the prior art. Such prior art gusseted bags are used, for example, in the bread packaging industry for containing loaves of bread. However, Applicant&#39;s invention contemplates using a gusseted bag with much shorter side walls, such that when it is placed on a rectangular mandrel it assumes more of a shoe-box shape. 
     First, the prior art gusseted bag is slit in corners at the open end of said gusseted bag, or stated differently, at the intersection of each side wall starting at the open end of the gusseted bag to a defined distance towards the closed end wall. The slits then define four flaps or flanges located at the open end of the gusseted bag. The gusseted bag can also be perforated along one or more sides, either on a side wall or at the closed end. In a preferred embodiment, the gusseted bag is placed over a rectangular shaped male mandrel. Once on the mandrel, the gussets (located on two of the side walls) are, in one embodiment, heat sealed to their respective side walls. Heat sealing the gussets in such fashion, which is optional, provides for increased rigidity of the side wall and helps maintain the rectangular shape of the package that is being formed. 
     Next, the gusseted bag is removed from the male mandrel and inserted into a rectangular shaped female mandrel. The female mandrel pulls the aforementioned flanges away from the open end of the gusseted bag and holds them in a position that is perpendicular to the side walls with which they are contiguous. Next, product, such as several pillow bags, is placed into the gusseted bag. The opening of the gusseted bag is then sealed by placing a single sheet or web of film over the opening and heat sealing this web to the flanges. 
     The resultant semi-rigid container is relatively simple and inexpensive to manufacture, yet also provides structural rigidity to the overall package. Applicant&#39;s container is rectangular shaped to facilitate stacking and is totally transparent, absent graphics placed on the container. 
     The above as well as additional features and advantages of the present invention will become apparent in the following written detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a prior art gusseted bag with modifications in accordance with Applicant&#39;s invention; 
         FIG. 2  is a perspective view in elevation of a gusseted bag mated with a rectangular male mandrel; 
         FIG. 3  is a perspective view in elevation of a gusseted bag placed inside a rectangular female mandrel; 
         FIG. 4  is a perspective view in elevation of a loaded gusseted bag immediately prior to sealing with the sealing web; and 
         FIG. 5  is a perspective view in elevation of the finished semi-rigid flexible film pack in accordance with Applicant&#39;s invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The starting point for Applicants invention is a prior art container referred to in the industry as a “gusseted bag.” A gusset is a pleat made into the bag. When a gusset is put into a bag then the bottom of the bag is squared, thus eliminating what is commonly referred to as “dog ears,” or the corners of the bag that would otherwise stick out. Examples of gusseted plastic bags include prior art containers for bread loaves. These containers have gussets proximate to two opposed side walls adjacent to the bottom (or closed end) of the bag. It is this type of gusseted bag, having gussets on opposed sides near the bottom of the bag that Applicant is referring to when referencing a “gusseted bag.” Such gusseted bags are available in many different sizes and shapes from, for example, Multi-Pak USA, Inc. of Dacula, Ga. 
       FIG. 1  shows a prior art gusseted bag that has been modified in accordance with Applicant&#39;s invention. Specifically,  FIG. 1  shows that slits  102  have been cut into the corners of the gusseted bag at its open end. Stated another way, a slit  102  is cut at the intersection  104  of each side wall  106 ,  108 , of the gusseted bag, with the slit  102  starting at the open end of the gusseted bag to a defined distance towards the closed end  107 . (While the term “intersection  104  of each side wall  106 ,  108 ” is used, it is understood that this “intersection” is in fact a crease in the film, as all the side walls  106 ,  108  are integral to each other.) Such defined distance, or length of the slit, in a preferred embodiment is about 0.25 to about 1.0 inches, or most preferably about 0.75 inches. Once these slits  102  are made, they define four flaps or flanges  103  located at the open end of the gusseted bag. 
     It should be noted that the general dimensions of the gusseted bag shown in  FIG. 1  are rectangular with short side walls  106 ,  108 , giving the end product, as will be discussed later, more of a shoe box sized configuration. This necessitates two wide side walls  106  and two narrow side walls  108 . In a preferred embodiment, the gussets  110  are associated with or proximate to respective narrower side walls  108 . However, Applicants invention contemplates that the gussets  110  could be associated with or proximate to any two opposing side walls  106 ,  108 . 
     When the gusseted bag is squared up, the preferred ratio of the width  114  of the wide side wall  106  (also referred to by Applicant as the length of the container) to the width  116  of the narrow side wall  108  (also referred to by Applicant as the width of the container) is in the range of 1.6 to 1.9. A typical range of sizes for a preferred embodiment container pursuant to Applicants invention requires a starting gusseted bag when squared up of from about 8 inches long  114  by 4.25 inches wide  116  by 5.5 inches tall  118  (measured from the bottom of the slit  102 ), to about 11 inches long  114 , to 6 inches wide  116 , to 6 inches tall  118 . The above-stated dimensions result in a finished container of the same size. 
     Also shown as a modification to a prior art gusseted bag in  FIG. 1  is a perforation  112  along one side wall  106 . This perforation  112 , placed in the side wall  106  by means known in the art, allows for access to the inside of the formed container by tearing at the perforations and removing the piece defined by such perforations  112 . This provides access to the interior of the formed container. 
     In a preferred embodiment the gusseted bag used as a starting point for Applicant&#39;s invention is constructed of a flexible film material, such as a single layer of polyethylene. Alternative materials that can be used include, but are not limited to, single layer polypropylene or a multilayer structure of polypropylene and polyethylene. The polyethylene is preferred because of its general durability, transparency, heat sealing characteristics, tear resistance and because it is generally inexpensive. The sheet thickness for a polyethylene gusset bag in accordance with Applicant&#39;s invention, is preferably between 2 mil and 3 mil. 
     Although the gusseted bag illustrated in  FIG. 1  is shown in an open configuration, giving it a boxy shape, one advantage of a gusseted bag is that it can lie flat, also in a rectangular shape. This feature of a gusseted bag makes shipping and storage of the gusseted bags prior to use with Applicant&#39;s invention easy and economical. 
     Once the slits  102  have been cut in the gusseted bag, and optionally the perforation  112  made in one or more side walls  106 ,  108 , or the closed end wall  107 , the gusseted bag is mated with or placed over a male mandrel. This is illustrated in  FIG. 2 . Unless otherwise noted, identical elements are identified by identical number designations throughout this Specification. 
     In  FIG. 2 , the modified gusseted bag is shown being placed over a male mandrel  120 . This male mandrel  120  shapes the gusseted bag into its rectangular form and holds it in such shape allowing for two heating elements  122  to be physically pressed against the area on the gusseted bag where each of the gussets  110  are located. The film that makes up a narrow side wall  108  and its respective gusset  110  is pressed between the surface of the inserted male mandrel  120  and the heating element  122  for a sufficient amount of time for the gusset  110  to heat seal against its respective side wall  108 . The heating element seals by conductive heat, impulse seal, or other similar techniques. In a preferred embodiment example wherein the film used on the gusseted bag is a single layer of polyethylene of an approximate thickness of 2.5 mil, heating elements  122  at a temperature of approximately 200 C, are held against the gusseted bag while over the male mandrel  120  for approximately 1 sec in order to adequately seal the gussets  110  to their respective side walls  108 . Heat sealing the gusset  110  to the side wall  108  increases the rigidity of the formed container, however is not required. An alternative embodiment of Applicant&#39;s invention forms the container described herein without heat sealing the gussets  110  to their respective proximate side walls  108 . 
     Referring now to  FIG. 3 , after the gussets have been heat sealed to their respective proximate side walls, the modified gusseted bag is next placed inside a female mandrel  124 . This female mandrel  124  comprises a means for pulling the flaps or flanges  103  away from the open end of the modified gusseted bag and holding them against the surface of the female mandrel  124 , as is depicted in  FIG. 3 . Such means can include applying a vacuum in the vicinity of the flanges  103 , when the gusseted bag is seated within the female mandrel  124 . The end result is that the flanges or flaps  103  become oriented perpendicular to their respective side walls, for reasons that will become apparent in reference to  FIG. 4 . 
     Once the gusseted bag is oriented as depicted in  FIG. 3  with the flanges  103  held down, product, such as a plurality of pillow bags (depicted in dashed lines in  FIG. 4 ), is loaded into the modified gusseted bag. Next, and again in reference to  FIG. 4 , a sheet or web of film  126  is placed over the open end of the gusseted bag. The outside edges of this sheet or web  126  are lined up with the outside edges of the four flanges  103  and subsequently heat sealed to said flanges  103 , thus forming a cover  126  or sixth wall/side for the finished six-sided container. After the web or cover  126  is heat sealed to the flanges  103 , the container has been formed and is removed from the female mandrel. It should be noted that the web  126  can optionally be perforated prior to application to the flanges  103 . Consequently, it is understood that any one or more of the six sides/walls of the formed container can have perforations that allow access to the interior of said formed container through the respective wall. 
     The end result of Applicant&#39;s method is shown in  FIG. 5 . It can be seen from  FIG. 5  that the web or cover  126  has been sealed over the open end of the modified gusseted bag by mating with the flanges  103 . While the cover  126  is shown in  FIG. 5  to form the top of the container, it should be understood that the entire formed container can be oriented with the cover  126  as the base or bottom of the container. Consequently, rather than referring to a top or bottom of the formed container, Applicant refers to a “covered end”  126  and its opposed “closed end” on the other side of the container, which would be the bottom of the container in  FIG. 5 . Also shown in  FIG. 5  is the gusset  110  heat sealed to its respective proximate side wall  108 . Shown within the formed container, illustrated in dashed lines, is product that is secure within the container. In this instance, the product illustrated is a plurality of pillow bags. These pillow bags in turn, in a preferred embodiment, contain a food, for example, and without limitation, potato chips, corn chips, tortilla chips, extruded products, baked dough products, nuts, candy, fruit pieces, dried meats, and other foods. 
     Although it can also be varying grades of opaque, the preferred embodiment of Applicant&#39;s container is formed with a flexible film that is transparent. As a consequence, the consumer is able to observe the product contained within the container. Graphics labels can be subsequently applied to any of the six sides of the container or, alternatively, graphics can be pre-printed on the gusseted bag itself and/or the cover/web  126  such that the formed container presents graphics on one or more of the six sides. As previously noted, and in reference to  FIG. 1 , perforations  112  can be made on any of the six sides allowing easy access to the interior of the container. Once formed, this container is a semi-rigid, yet flexible container suitable for presenting several smaller containers (for example the pillow bags) as one single unit. 
     Pillow bags are common in the prior art and are typically made by vertical form, fill and seal machines using a single web of film wrapped around a forming tube. The web of film then receives a back seal to form the web into a tube. An end seal is placed at the bottom of the tube, and product is then dropped through the tube into the pouch formed by the end seal. Another end seal is then formed above the level of the product, and the tube is cut at this upper end seal, thus forming the familiar pillow bag. These pillow bags are frequently used for containing snack foods such as potato chips, corn chips, pretzels, cookies, and other foods. 
     Such pillow bags have a higher rigidity at the end seals than along the rest of the body of the bag by virtue of the fact that the end seals are at least double (and in some locations, triple or quadruple) the thickness of the walls of the bag. Consequently, in a preferred embodiment of Applicant&#39;s invention, when pillow bags are placed within the modified gusseted bag, they are oriented such that the end seals of the pillow bags are parallel to the side walls of the modified gusseted bag. Stated differently, when loaded in this preferred embodiment, the container holds a plurality of pillow bags all oriented with their end seals running perpendicular to the top and bottom of the container when displayed for sale. As a consequence, these end seals from the pillow bags provide additional rigidity and vertical support for the formed container. 
     While the invention has been particularly shown and described with reference to a preferred embodiment, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.