Abstract:
A reinforced cross laminated corrugated paperboard bulk container has an outer component with corrugations running in a first direction, and an inner liner laminated to the outer component, with the liner having corrugations extending perpendicular to the corrugations in the outer component. Reinforcing strands are in both the liner and the outer component, extending perpendicular to the respective corrugations thereof. Interlocking top flanges are on the top edges of the outer component, and interlocking bottom flanges are on the bottom edges thereof. The interlocking bottom flanges include a chevron shaped locking slot in one flange and a locking tab on an opposed bottom flange. Folds extend across the bottom flanges to enable them to deflect and slide relative to one another during set up of the container. Vertical scores in the liner are pre-broken prior to laminating it to the outer component.

Description:
TECHNICAL FIELD 
     This invention relates generally to bulk shipping and storage containers. More particularly, the invention relates to a bulk container made of reinforced cross-laminated corrugated paperboard. In a preferred embodiment the container has interlocking full bottom flaps and is especially adapted for containing fluid products. 
     BACKGROUND ART 
     In the bulk handling of materials, and especially fluid or flowable materials such as liquids, powders and granules, containers of 20 to 80 gallon capacity are commonly used to transport and store the material. These containers should be capable of withstanding the weight of the contents and of being stacked on top of one another. They should also be capable of withstanding the rough handling to which they may be subjected, and be capable of being handled with mechanized equipment. 
     A variety of containers have been developed in the prior art in an effort to meet these criteria, including drums made of metal or fibre, plywood bins, and corrugated paperboard containers. While plywood bins and drums made out of metal or fibre possess the requisite strength and durability, they are expensive to manufacture, store and ship. 
     Corrugated paperboard containers are less costly to make and generally can be collapsed for compact storage and shipment. However, when filled with a fluid product the sidewalk of the container may bulge outwardly, and depending upon the size of the container and weight of the material used in its construction it may be difficult to set up. Further, a flexible bag liner is commonly used when a fluid material is to be contained, and unless special consideration is given to how the container is constructed, the liner may be damaged by elements of the container protruding into the interior of the container. 
     Bulk containers may be palletized for ease and convenience of handling, and it is desirable that the container or containers efficiently fit the pallet, i.e. that they do not overhang the edges of the pallet, or the edges of the pallet do not extend an excessive distance beyond the perimeter of the container or containers supported thereon. Pallets typically utilized are 40×48 or 44×44 or 44×54 inches in size and are square or rectangular in shape. Cylindrical drums do not efficiently fit a pallet because the circular footprint of the drum leaves void spaces between adjacent drums and at the corners of the pallet. Conventionally constructed square or rectangular containers of corrugated paperboard can be sized to fit a pallet, but if the sidewalls bulge outwardly they can extend beyond the perimeter of the pallet and be subject to damage. 
     Conventional corrugated paperboard containers strong enough to hold fluid material are either difficult to set up from a flattened condition and/or are too hard to manufacture and/or are too expensive for the end-user. Bulging sidewalls and difficulty in setting them up from a knocked down or flattened condition are the major problems with conventional designs. 
     There is need, therefore, for a bulk container made of corrugated paperboard that can take the place of a 20 to 80 gallon fibre drum or metal barrel, which can ship flat and be easily opened up for filling, and once it is empty, knocked down flat again for either re-use or recycling. Further, it would be desirable to have a container that can fit four on a pallet, that is reinforced against bulging of the sidewalls, and that maintains proper containment thereby eliminating potential contamination. 
     DISCLOSURE OF THE INVENTION 
     The present invention solves the foregoing problems through a combination of features, including cross lamination of a corrugated inner liner and an outer component, double score profiles on the 180 degree folds, use of re-enforcing tape such as Sesame Tape or a comparable re-enforcing strand in the liner and in the outer component, with the reinforcing tape extending perpendicular to the respective corrugations in the liner and in the outer component, and pre-breaking of the scores in the liner before lamination with the outer component. The cross lamination of the inner liner and outer component, together with the cross-hatch pattern created by the direction of the reinforcing tape or strands, fortifies the sidewalls against bulge and permits use of lower grades of material in the cross corrugation liner. 
     In a preferred embodiment of the invention the container is sized so that four of them can fit on a single pallet. Although the structural limit to a container is governed by the machines used to produce the corrugated fibreboard and the laminator with which the components are joined, the smaller size containers are difficult to fabricate so that they can be shipped in a knocked down condition and easily erected by the user. Pre-breaking the scores of the cross laminated inner liner before it is laminated to the outer component provides ease of fabrication and makes it easier for the end-user to open up the container from a knocked down condition. By pre-breaking the scores deeper definition is given to the body scores and the surface tension is reduced when the panels are folded to form the container. In accordance with the invention, an inner jig is employed during the folding operation at the point of closing the glue joints on the container. The jig helps to form a more uniform geometry by forcing the 180 degree fold ends into two 90 degree pairs of double score features at the vertical corners of the container. 
     The resistance to folding of bulk containers, especially the smaller sizes that are in high demand, is of paramount concern, and has been one of the major weaknesses of previous designs. Resistance to folding is created by the small panel sizes and the laminated construction. To overcome this resistance in the present invention, the scores in the inner liner are pre-broken before the liner is laminated to the outer component, and double scores are placed at the point of the 180 degree folds. The double scores lessen the surface tension on the outermost facing, and each of the double scores, individually, only has to fold 90 degrees in the container of the invention, together forming the 180 degree fold. 
     In a preferred embodiment the container of the invention has an interlocking bottom flap construction that minimizes the risk of failure during handling, and avoids pinching of a bag liner when a bag is used. The interlocking bottom flaps are designed to provide trouble-free continuous performance during handling even when liquids are stored in the container. The interlocking bottom flaps include a pair of opposed intermediate or inner flaps that provide a full overlap on the inside of the container bottom, with a smooth surface to prevent pinching a bag liner and causing a leak when a bag is used inside the container. Both intermediate flaps have perf scores (also known as cut and crease) just past the points of overlap of the intermediate flaps to assist the user in moving the flaps to their operative positions by preventing binding on the outer flaps which interlock. The interlocking structure of the outer flaps comprises a narrowed tab on the end edge of one outer flap, and a shaped slot adjacent the end edge of the opposing outer flap. The tab has rounded corners to allow entry into the opposing slot, and the shape of the slot inhibits bending of the tab during use. The outer flap that contains the slot also has angled perf scores to facilitate bending of this flap down into the container far enough to permit the tab to be engaged in the slot during set-up. Once engaged, the two interlocked flaps are pulled back up to create a stable flat surface on which the container rests during use. The shaped slot incorporates an arc so that the slot has a generally chevron shape, rather than the typical linear or rectangular geometry that is commonly seen in similar interlocks. Conventionally shaped slots apply force in a straight line across the tab when excessive force is exerted against it from product inside the container, causing the tab to bend. The chevron shape of the slot of the invention helps prevent bending of the tab by dispersing the excessive pressures in a non-linear pattern. 
     The liner can be any flute combination, such as C, B, A, AA, AC, BC, AB, AAA, ACA, CAA, CBA, etc, and combinations thereof. The outer half-slotted-container (HSC) of the invention also can comprise any of the same flute combinations. Selection of the flute combinations is governed by the desired performance level of containment and stacking strength. 
     The container of the invention can have any dimensions and any rectangular shape tailored to whatever a customer may want, being limited only by a manufacturer&#39;s ability to fabricate the container with the attributes of the invention disclosed herein. 
     Although the preferred construction has an interlocking, full overlapping bottom flap construction, it could comprise a set of partial flaps or flanges, if desired. A full bottom could also be constructed, but without the overlap that normally would be used in an application for liquid transport. 
     The preferred embodiment of container according to the invention has interlocking flanges at its upper end, but it could be constructed with no flaps or flanges at its upper end, or partial flaps without interlocking characteristics, or a full flap closure with or without any overlap. The preferred embodiment comprises interlocking flanges such as shown in U.S. Pat. No. 6,076,734, the disclosure of which is incorporated in full herein by reference. Interlocking top flanges in combination with the other features described earlier aids in the needed sidewall rigidity, and in turn helps prevent bulging and ensures proper product containment. Proper containment is necessary for secure storage and transport, whether the product is a food or an industrial ingredient. 
     Although the preferred embodiment has two reinforcing strands of tape (Sesame Tape or comparable types or brands) on the outer component and four strands on the cross laminated inner liner, the container of the invention could have any number of reinforcing strands, from no strands to eight strands per component, limited by the functionality for customer use and the manufacturer&#39;s ability to produce. 
     Further, a variety of flute configurations and combinations of the outer corrugated and the inner cross laminated corrugated could be used, such as singlewall (A-flute, B-flute, C-flute or any other flute size currently available) outer, and a cross laminated triplewall (AAA, ACA, CAA, CBA or any other flute combination currently available) inner. The inner cross corrugation could be any flute combination of doublewall and still provide adequate flexural rigidity which is needed for the practical use of the container. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing, as well as other objects and advantages of the invention, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, wherein like reference characters designate like parts throughout the several views, and wherein: 
         FIG. 1  is a partially exploded top perspective view of four containers according to the invention resting on a pallet. 
         FIG. 2  is a top plan view of a blank for making the outer component of the container of the invention. 
         FIG. 3  is a top plan view of a blank for making the inner liner of the container of the invention. 
         FIG. 4  is a top plan view of a blank for making a cap for use on the container of the invention. 
         FIG. 5  is a top plan view showing the inner liner laminated to the outer component preparatory to folding the container and gluing the glue flaps together. 
         FIG. 6  shows the container in an inverted position and depicts the series of steps performed in folding the interlocking bottom flaps into operative interlocked position. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A container made in accordance with a preferred embodiment of the invention is indicated generally at  10  in  FIG. 1 , wherein four of the containers are shown resting on a pallet P. 
     The container is rectangular in shape and has four sidewalls  12 ,  13 ,  14  and  15 , joined together along vertical scores  16 A,  16 B,  16 C and  16 D at the corners, an open top end partially closed by interlocking top flanges  17 A,  17 B and  18 A,  18 B, and as seen best in  FIG. 6  a closed bottom end  19 . A cap  20  is placed over the upper end of each container and in  FIG. 1  is shown removed from one of them. 
     Construction of the container is best understood with reference to  FIGS. 2-6 . 
       FIG. 2  shows a blank B 1  for making the outer component  21  of the container. The blank comprises four sidewall panels  12 ,  13 ,  14  and  15  joined together along the respective scores  16 A,  16 B and  16 C, with a glue flap  22  foldably joined to one end edge of the blank along fold  16 D which effectively joins panel  12  to panel  15  when the container is glued up. The scores  16 A and  16 B are double scores as more fully described and illustrated in applicant&#39;s prior U.S. Pat. No. 4,693,413, the disclosure of which is incorporated in full herein by reference. As described in that patent, the scores  16 A and  16 B extend along those corners joining sidewall panels that move through 180 degrees between the unfolded position of the blank and the folded flat position of a container made from the blank. 
     The partial top flanges  17 A,  17 B and  18 A,  18 B are foldably joined to top edges of the respective sidewall panels along fold lines  23 . The top flanges are constructed substantially the same as and function in substantially the same way as described and shown in applicant&#39;s prior U.S. Pat. No. 6,076,730, the disclosure of which is incorporated in full herein by reference. Thus, opposite side edges of flanges  18 A and  18 B are cut away along curvilinear lines to define a locking tab  24  on the outer end edge thereof and rounded shoulders  25  on the opposite side edges. Flanges  17 A and  17 B have notches  26  cut in their outer end edges adjacent the opposite sides thereof, defining rounded corners  27  on opposite side edges of the flanges. As seen best in  FIG. 1 , when the flanges are folded into operative position the corners  27  on flanges  17 A,  17 B engage beneath shoulders  25  on flanges  18 A,  18 B, and the side edges of tabs  24  engage in the notches  26 , with the tabs  24  on flanges  18 A,  18 B lying beneath the adjacent edges of flanges  17 A,  17 B, interlocking the flanges together. It will be noted that the notches  26  and corners  27  in the present invention are rounded as distinguished from the rectilinear shape of these elements in U.S. Pat. No. 6,076,730, facilitating alignment and engagement of the interlocking portions of the flanges when they are being folded into their interlocking positions. 
     In the preferred embodiment shown in  FIG. 2 , substantially identical bottom flaps  30 A and  30 B are foldably joined to bottom edges of respective sidewall panels  12  and  14  along folds  31 , and bottom flaps  32  and  33  are foldably joined to bottom edges of respective sidewall panels  13  and  15  along folds  34 . In a container erected from the blank the flaps  30 A and  30 B comprise inner flaps and the flaps  32  and  33  comprise outer flaps. 
     The flaps  30 A and  30 B are rectangular in shape, and a line of perforations define a perf score  35  across each flap adjacent but spaced from the folds  31 . When a container is erected from the blank, the flaps  30 A,  30 B are disposed in opposed relationship to one another and each flap extends most of the way across the bottom of the container, with the free end edge of each flap terminating just short of a respective perf score  35  in the opposed flap. This arrangement helps facilitate folding of the flaps into operative position as depicted in  FIG. 6 . The side edge of flap  30 A is recessed slightly at  36 A adjacent glue flap  22 , and one side edge of flap  30 B is recessed slightly at  36 B adjacent its outer end edge. These recessed areas provide clearance for the glue flap when the flaps are folded into their operative positions in a container erected from the blank 
     The side edges of flap  32  are cut away along curvilinear lines to define a narrowed locking tab  37  on the outer end edge thereof, and rounded shoulders  38  on opposite side edges. The locking tab and shoulders cooperate with flap  33  as described below to lock the bottom flaps in operative position across the bottom of a container erected from the blank. 
     Bottom flap  33  is generally rectangular in shape and a pair of diagonal fold scores  40  and  41  extend from opposite corners of the flap closely adjacent the fold  34  to the outer end edge thereof in inwardly spaced relation to opposite side edges of the flap, defining triangularly shaped corners  42 . A generally chevron shaped slot  43  is formed in approximately the middle of the flap  33  for receiving the locking tab  37  on flap  32  as described hereinafter. 
     In the preferred embodiment as shown in  FIG. 2 , a pair of reinforcing strands  45  of Sesame Tape or other reinforcing strand known in the art extends across the blank from one end edge to the other approximately midway between the top and bottom edges thereof. As indicated by the arrow “A” in  FIG. 2 , the corrugations of the outer component  21  extend perpendicular to the top and bottom edges of the blank, and the reinforcing strands extend perpendicular to the corrugations. 
     A blank B 2  for making the inner liner  50  of the container of the invention is shown in  FIG. 3 . The blank B 2  is rectangular in shape and comprises four sidewall panels  51 ,  52 ,  53  and  54  joined together along respective scores  16 A′,  16 B′ and  16 C′, with a glue flap  55  foldably joined to one end edge of the blank along fold  16 D′ and which effectively joins panel  51  to panel  54  when the container is glued up. The scores  16 A′ and  16 B′ are double scores as more fully described and illustrated in applicant&#39;s prior U.S. Pat. No. 4,693,413, the disclosure of which is incorporated in full herein by reference. In a container erected from the blank, the scores  16 A′ and  16 B′ in the liner extend contiguous with the scores  16 A and  16 B in the outer component, and the scores  16 C′,  16 D′ extend contiguous with the scores  16 C,  16 D, respectively. The scores  16 A′,  16 B′,  16 C′ and  16 D′ in the liner are pre-broken with a jig (not shown) prior to lamination of the liner  50  to the outer component  21  to facilitate fabrication of the container and to make it easier for a user to open up a flattened container into its operative position. In the preferred embodiment as shown in  FIG. 3 , a first pair of reinforcing strands  56  of Sesame Tape or other reinforcing strands known in the art is applied to a midportion of sidewall panel  52 , extending from the bottom edge thereof to the top edge, and at least one reinforcing strand  56  (two are shown in  FIG. 3  and one in  FIG. 5 ) is applied to a midportion of panel  54 , extending from the bottom edge to the top edge of that panel. As indicated by the arrow “B”, it will be noted that the corrugations in the liner extend in a direction perpendicular to the corrugations in the outer component. Thus, the reinforcing strands in the liner extend perpendicular to the corrugations in the liner, and as seen best in  FIG. 5  they extend perpendicular to the reinforcing strands in the outer component in a container erected from the blank. 
       FIG. 5  shows the inner liner  50  laminated to the outer component  21  to form a laminated blank  57  from which the container is erected. It will be noted that the liner is shifted to the left as viewed in this figure, with the glue flap  55  on the liner projecting beyond the glue flap  22  on the outer component, and the opposite end of the liner inset relative to the adjacent end of the outer component, defining a space  58  for attachment of the glue flap  55 . 
     To set up a container from its flattened condition to its expanded operative condition, it is opened into a tubular configuration and the partial top flaps are folded into their operative interlocked position as described previously herein. The container is then inverted so that it rests on its top end, and the bottom flaps are folded into their operative interlocked positions as depicted in  FIG. 6 . Flaps  30 A and  308  are first folded inwardly into the container, followed by inward folding of flap  33  and then flap  32 . The flaps are pressed downwardly into the container until the locking tab  37  engages in slot  43 , and the flaps are then pulled outwardly into a generally flat position across the bottom of the container. It will be noted that the perf scores  35  in flaps  30 A and  30 B and the folds  40  and  41  in flap  33  enable these flaps to deform slightly during the folding operation to facilitate set up of the container. 
     A blank B 3  for making the cap  20  is shown in  FIG. 4 . The blank comprises a rectangular center panel  60  with substantially identical end flaps  61  and  62  foldably joined to opposite end edges thereof along folds  63 , and substantially identical side flaps  64  and  65  foldably joined to opposite side edges thereof along folds  66 . As seen in  FIG. 1 , the flaps  61 ,  62  and  64 ,  65  interlock with one another to form a cap skirt  67 . The interlocking construction of cap  20  is substantially the same as that for the liner tray 110 disclosed in U.S. Pat. No. 7,172,108. Thus, flaps  61  and  62  each has an assembly flap  68  on opposite side edges thereof, with an outer corner cut away at  69  to define a locking tab  70  that is inserted into angled slit cuts  71  in the flaps  64  and  65  adjacent opposite ends thereof. 
     While particular embodiments of the invention have been illustrated and described in detail herein, it should be understood that various changes and modifications may be made in the invention without departing from the spirit and intent of the invention as defined by the appended claims.