Patent Publication Number: US-2002011513-A1

Title: Collapsible corrugated plastic box

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] This invention relates to collapsible boxes and more particularly a collapsible box made of corrugated plastic.  
       [0003] 2. Description of the Prior Art  
       [0004] Collapsible corrugated boxes and cartons made of paperboard are well known in the art. Such boxes and cartons typically include vertical side walls and top and bottom flaps on the side walls for forming a bottom end wall and a top closure for the box. The paperboard is crushed along lines between adjacent side walls and between the side walls and the flaps to form “score lines” or hinge lines for bending the paperboard.  
       [0005] It is known to provide a foldable carton having hinged together bottom panels for automatically forming the carton bottom when the carton is erected. Cartons having such automatically forming bottoms are disclosed in U.S. Pat. Nos. 2,327,709 and 4,289,268.  
       [0006] It is also known to provide a plastic box as is disclosed in U.S. Pat. No. 4,948,039. That patent discloses a container made out of fluted plastic having integral hinges between the walls and flaps and having Velcro® strips for fastening the walls and panels together. The hinges in the container are made by cutting one facing sheet in the fluted plastic and hinging the walls and flaps on the other (uncut) facing sheet. The container disclosed in that patent is said to be easily collapsible and reusable.  
       [0007] There is a need for an improved collapsible box made of corrugated plastic that is economical and suitable for high speed manufacture and erection. An improved plastic carton is needed that is more durable and resistant to tearing. A plastic box is needed that will set up better when erected and not collapse on itself. A corrugated plastic carton is needed that includes an automatically lockable bottom and a plastic box that can be reused many times.  
       SUMMARY OF THE INVENTION  
       [0008] This invention satisfies the needs for an economical plastic box that can be manufactured using high speed equipment and which is durable and capable of being reused many times.  
       [0009] This invention provides a collapsible box made of corrugated plastic, which has improved hinge/score line configurations between walls and panels and improved hand holds. A plastic box of this invention preferably has an automatically lockable bottom to facilitate erection of the box, and can be easily collapsed for return shipment and reuse.  
       [0010] A collapsible box of this invention may have offset scoring for the bottom flaps so the box sets up better. Offset scoring produces a box with less memory when erected, so the box stays erected without collapsing on itself.  
       [0011] The score lines in a box of this invention preferably terminate short of slots cut between panels and flaps so the corrugated plastic will have increased resistance to tearing. The box also preferably has hand holds defined by cut lines that terminate in rounded corners, which also reduce risk of tearing the plastic.  
       [0012] Accordingly, an object of this invention is to provide an improved collapsible box made of corrugated plastic.  
       [0013] The above and other objects and advantages of this invention will be more fully understood and appreciated by reference to the following description and the attached drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014]FIG. 1 is a perspective view of a collapsible box of the type suitable for use with this invention.  
     [0015]FIG. 2 is a fragmentary cross-section through corrugated plastic for use in a box of this invention.  
     [0016]FIG. 3 is a plan view of a pattern or blank for a box having a collapsible lockable bottom suitable for use in this invention.  
     [0017]FIG. 4 is a bottom view of an erected box showing the locked bottom flaps.  
     [0018]FIG. 5 is a fragmentary view showing an offset score in a collapsible box of this invention.  
     [0019]FIG. 6 is a fragmentary cross-section through a hinge score of this invention before the corrugated plastic is folded at the score.  
     [0020]FIG. 7 is a fragmentary cross-section through a hinge score of this invention showing the corrugated plastic folded at the score.  
     [0021]FIG. 8 is a fragmentary view showing a diagonal score in a collapsible box of this invention.  
     [0022]FIG. 9 is a fragmentary view of a top corner of a box of this invention showing the score lines at the corner intersection of the side walls and top flaps.  
     [0023]FIG. 10 is a fragmentary side elevation of a vertical width wall of a box of this invention showing a hand hold in the width wall.  
     [0024]FIG. 11 is a fragmentary cross-section through an alternative corrugated plastic that can be used in the practice of this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0025]FIG. 1 illustrates a collapsible box  10  that is suitable for use of the present invention. The box  10  is preferably rectangular or square in footprint but may also have hexagonal or other configurations. The box has a pair of vertical width walls  12 , a pair of vertical length walls  14 , and a bottom closure  20  as is described below. The box optionally includes a pair of top width wall flaps  16  and a pair of top length wall flaps  18 ; it can also be in the form of a half slotted container, which does not include top flaps.  
     [0026] The box  10  has vertical hinge lines  22  between the width walls  12  and length walls  14 , hinge lines  24  between the width walls  12  and width wall flap  16 , and hinge lines  26  between the length walls  14  and length wall flaps  18 . The box also has hinge lines between the width walls  12 , length walls  14  and bottom end wall flaps as is described below.  
     [0027] All score lines in the box  10  facilitate erecting and collapsing the box. In accordance with this invention, a box  10  may have unique hinge line/score line configurations which improve the performance and durability of the box.  
     [0028] Box  10  may also include hand holds  28  in opposite width walls  12 . The hand holds  28  are defined by a cut line  30  completely through the box material and may have a hinge/score line  32  at the top of each hand hold as is described below in more detail.  
     [0029] The top width flaps  16  may have hinge/score lines  34  across them for forming a bend at the line, and the top length wall flaps may have L-shaped flaps  36  in them for providing slots to receive corners of the width flaps when the box  10  is closed by downward folding of the flaps  16 ,  18 . Each L-shaped flap  36  may be defined by a cut line  38  and a hinge/score line  40  so the flap can be hinged into the box to permit insertion of the corners of flaps  16 . The second flaps  36  provide a ski so the flaps can be inserted into the box without damaging the contents of the box.  
     [0030] A box  10  of this invention may be made of corrugated sheet plastic material  41  such as that shown in FIG. 2. Corrugated plastic  41  is well known material, but has received only limited application in collapsible boxes (see U.S. Pat. No. 4,948,039). Corrugated plastic  41  has parallel facing sheets  42 ,  44  and spaced, integral interconnecting ribs  46  between the facing sheets. The plastic sheet material  41  can be easily extruded from a variety of plastic resins such as polyethylene, polypropylene, and the like. A box of this invention may also be made of conical plastic sheet material  80  such as that shown in FIG. 11, which includes facing sheets  81 ,  82  bonded to a corrugated intermediate sheet  83  as for example by melt bonding, ultrasonic bonding or an adhesive.  
     [0031]FIG. 3 shows a blank  48  for a preferred embodiment of a box  10  of this invention. The blank includes panels which form the width walls  12 , length walls  14 , top width flaps  16 , top length flaps  18 , bottom width flaps  50 , bottom length flaps  52 ,  54  and glue flap  56 . Score/hinge lines are also provided in the blank  48 . These score lines may include score line  22  between the width walls  12  and length walls  16 , score lines  24  between the width walls  12  and length wall flaps  16 , score lines  26  between the length walls  14  and length wall flaps  16 , scores  58  between the width walls  12  and bottom end wall flaps  50 , score lines  60  between the length walls  14  and the length wall flaps  52 ,  54 , score lines  60  in the top width wall flaps  16 , and score lines  62  in the bottom end wall flaps  50 . The blank  48  also preferably has hand holds  28  in the width walls  12 . The score lines  62  in each of the bottom width wall flaps  50  bisect the corner where the width wall flaps meet the bottom length wall flap  52 ,  54 , length wall  14  and width wall  12 , and defines a tab portion  64 , which is to be adhesively bonded to the adjacent length flap to form the automatically lockable bottom closure for a box made from the blank  48 .  
     [0032] Manufacture of a box  10  from the blank  48  is effected by shaping the blank into its box shape and gluing or otherwise connecting glue flap  56  to the exterior surface of length wall  14 . The bottom flaps  50 ,  52 ,  54  are folded into a bottom closure, with flap  54  being folded first, followed by flap  52  and then flaps  50 . Adhesive or glue has preferably been applied to the interface between tabs  64  and flaps  52 ,  54  to adhesively bond the tabs to the flaps at  66  as shown in FIG. 4. Alternatively, the tabs  64  can be joined or connected to flaps  52 ,  54  by ultrasonic welding or a hook and loop closure.  
     [0033] In accordance with this invention, the hinge lines between the side walls  12 ,  14  and the bottom end flaps  50 ,  52 ,  54  of a box are preferably vertically offset as is shown in FIG. 5. Such hinge lines preferably are formed by a crushed score line  68  and a perforated score line  70  parallel to the crushed score line. The two score lines  68 ,  70  may be spaced apart approximately one to two times the thickness of the corrugated plastic sheet material. The crushed score line  68  is formed by well known techniques in which a score tool or indenter is pressed against one face  42  of the corrugated material to collapse or crush the connecting ribs  46  in the material (FIG. 6). The perforated score  72  is a line of perforations cut through one facing sheet of the corrugated plastic. The crushed score  68  is preferably on the inside face (toward inside of box) of the plastic, and the perforations in the perforated score are preferably through the exterior face of the plastic, and the perforated score  70  is preferably the upper score in the hinge line. However, such locations of the scores are not critical to the invention.  
     [0034]FIG. 6 shows the parallel scores  68 ,  70  which form a hinge line of this invention, before the plastic  41  is folded or hinged, and FIG. 7 shows the plastic after it has been folded. The weaker perforated score  70  is designed to fold first and provide the desired dimensional control in the manufacture of the box. The crushed score  68  provides another bend point for the flap so each score has to accommodate only 90° of folding. This double hinged score enables the flaps to fold more easily and accurately as compared to a single score.  
     [0035] The vertically offset, horizontal scores  68 ,  70  at the bottom of adjacent walls  12  and  14  as seen in FIGS. 5, 6 and  7  provide more stability to a box of this invention. A box having such an offset score sets up better and has less memory when erected. The reduction in memory enables the box to stay erected without collapsing on itself. The bottom full overlap flap  54  (FIG. 3) also tends to lay more flat in boxes with offset scores, which is beneficial when filling the box with light weight products like potato chips.  
     [0036]FIG. 8 shows diagonal hinge/score lines that may be used as an alternative to the offset scores of FIG. 5. In the embodiment of FIG. 8, the score lines  72 ,  74  are parallel to each other, but extend diagonally or at an angle (about 5-10°) to the score line  22  between the walls  12 ,  14 . This alternative is more typically used when the bottom or top closure on the box has panels adapted to be closed and interlocked by a conventional French fold, instead of an automatically locking bottom closure as illustrated in FIGS. 1 and 3. The purpose of the horizontally running diagonal scoring is to alleviate the stress and memory involved when all the scoring is on the same plane when mechanically interlocking the top or bottom flaps, commonly known as French Folding the box. If the scores run on the same plane, the flaps do not lay flat when interlocked; they bow outwardly a great deal. This is partially caused by the material being on the same plane and trying to occupy the same space, when in reality, one flap need to be a little lower (approximately the thickness of the material being folded) than the adjacent interlocking flap. In order for the flaps to lock together, on each flap, half is above the adjacent panel on one side, and tucked underneath the adjacent panel on the opposite side. Therefore, the score needs to not run parallel to the floor, but diagonally to accommodate the flap being higher on one end than the other. The diagonal scoring allows the flaps to lay flatter when engaged and helps minimize the possibility of a load tipping due to the flaps bowing too much using conventional scoring.  
     [0037]FIG. 9 shows additional features of the bend/score lines in a box of this invention. As seen in this figure, the score lines  22 ,  24 ,  26 ,  34  between the walls  12 ,  14  and flaps  16 ,  18  terminate short of the edges of the flaps and short of the slots cut between panels. For example, hinge/score line  34  in flap  16  and hinge/score lines  24 ,  26  between walls  12 ,  14  and panels  16 ,  18  terminate approximately ½-1½ inches and preferably 1 inch (1″) short of the edges of the flaps  16 ,  18 . Terminating the scores short of the flaps helps reduce weak points that could start a tear. Tears tend to propagate in plastic once a tear has started. Accordingly, prior art boxes having scores that extend into the slots between flaps are much more susceptible to tearing than are boxes of this invention.  
     [0038] The vertical hinge/score lines  22  also terminate short of the slot  17  between flaps  16  and  18 . A gap of unscored plastic approximately ½ inch long is left at the end of each vertical score. This helps reduce weak points that could be the start of a tear in the plastic.  
     [0039]FIG. 10 shows a hand hold in a vertical width panel  12 . The hand hold is formed by a cut line  30  across the bottom and up both sides of the hand hold to define a flap  29  of plastic in the hand hold. It further includes a score line  32  across the top of the hand hold  28  which facilitates hinging of the flap  29  of plastic. The score line  32  can be either a crushed score or a perforated score and may be in either the inside or outside facing sheet in the plastic. However, the score line  32  is preferably a crushed score on the inside face of the plastic. In accordance with this invention, the cut line  30  ends in a radius or rounded corner  76  at the top of the hand hold  28  on both sides of the hand hold. The rounded corners  76  move the stress point in the plastic away from the top end of the vertical sides of the hand hold  28  and spreads the stress point to reduce risk of tearing the plastic during lifting of a box of this invention. Conventional hand holds, which do not include rounded corners and which end parallel to the flute lines, tend to tear easily. The rounded corners  76  of the preferred embodiment shown in FIG. 10 spread the load across the score line  32 .  
     [0040] It is therefore seen that this invention provides an improved collapsible box made of corrugated plastic that can be manufactured and assembled economically by high speed equipment. The box is more convenient to use and also more durable than prior art boxes. It will be apparent to those skilled in the art that numerous modifications can be made to the preferred embodiments selected for illustration without departing from the invention or the scope of the claims appended hereto. For example, hook and loop fasteners, such as those made under the trade designation Velcro® by the Velcro Company, could be used to effect closure of the top and/or bottom of the box.