Abstract:
An easy-open folding carton having a manufacturer&#39;s joint in which two panels are joined by an adhesive. One of the two panels includes a plurality of punch scores. The other panel is coated with a coating and includes a plurality of uncoated “knock-outs” that are aligned with the punch scores. The adhesive is disposed between the two panels in alignment with the knock-outs and punch scores. The panel that includes the punch scores is preferably coated, except for an uncoated stripe that extends through the approximate center of the punch scores. The present invention also provides a method for manufacturing a carton including the steps of (a) forming a carton blank having an adhesive panel and a first panel, (b) forming punch scores in one of the adhesive panel and the first panel, (c) coating the other of the first panel and the adhesive panel leaving a pattern of uncoated knock outs positioned to align with the punch scores in the assembled carton, (d) folding the blank into a carton, and (e) securing the adhesive panel to the first panel by an adhesive disposed between the punch scores and knock outs.

Description:
BACKGROUND OF INVENTION  
         [0001]    The present invention relates to cartons and, more specifically, to paperboard folding cartons and methods for manufacturing the same.  
           [0002]    Folding cartons are well known in the packaging art. Cartons are typically constructed from flat blanks that are pre-cut and pre-scored on sheets of paperboard. The carton blank will have a number of panels to form the sides of the carton. A blank for a rectangular carton, for example, will have four main panels, which form the four sides of the carton. A manufacturer&#39;s joint, or closing tab, attached to one end of the blank is generally used to secure the shape of the carton after it is folded. This tab is generally connected to one of the panels of the blank by an adhesive.  
           [0003]    The adhesive in a typical carton forms a strong bond between the tab and the panel. This bond between the tab and the panel has a high shear strength, which means when the panel and tab are moved against each other laterally, such as in a rubbing motion, it is difficult to separate them. This keeps the carton from opening during shipping and storage. The adhesive bond also generally creates a high peel strength, which is the force required to pull the tab away from the panel in a generally perpendicular direction. A high peel strength makes it difficult to tear the carton open.  
           [0004]    To conserve paper, and to reduce cost and labor, it has become desirable in the packaging industry to print product information on the inside of the product carton. This eliminates the need for a printed insert detailing the characteristics and uses of the product. To read the printed information, the carton must be opened; but, so far the methods devised to facilitate this have been less than satisfactory.  
           [0005]    Tearing at the location of the adhesive can generally open the carton. The problem with this method, however, is that it is difficult to get a clean tear. Due to the high peel strength of a typical carton, the tab and first panel often will not separate completely when the user tears at the carton. Frequently the inside of the carton is torn, which makes it difficult to read the printed interior of the carton. Even if the carton is not torn, the separation of the tab from the first panel can cause delamination of the interior of the carton. This removes the surface layer of the paperboard, which is where the printed material is located. Again, this makes it very difficult to read the information on the inside of the carton.  
           [0006]    Another method used to aid in opening the carton is to die-cut perforations into the paperboard along a pre-scored line. The user will then tear along the perforation to open the carton. While this eliminates the problems associated with high peel strength, the process introduces other deficiencies. First, aesthetically this method is lacking. After a perforation is made, cut and exposed fibers remain along the perforation. Second, it is difficult to vary the amount of force needed to open the carton with this method. A high degree of perforation, which would make opening the carton easier, would affect the integrity of the carton. Increasing the degree of perforation would also increase the chance of the carton opening during filling and/or shipping. As a result, the degree of perforation, and thus the ease of opening, is limited. Additionally, since the perforation is exposed when the carton is folded, there is an increased possibility of unintentional tears along the perforation.  
           [0007]    It is therefore desirable in the art to have a carton designed to be easily opened with varying degrees of force. It is also desirable to have a carton with a low peel strength designed to eliminate delamination when opening the carton.  
         SUMMARY OF THE INVENTION  
         [0008]    The aforementioned problems are overcome by the present invention wherein a folding carton is provided with a manufacturer&#39;s joint having one panel with a plurality of punch scores and another panel that defines a plurality of knock-outs aligned with at least some of the punch scores. The two panels are joined to one another by an adhesive disposed between the punch scores and knock-outs.  
           [0009]    In a preferred embodiment, the punch scores are disposed on the manufacturer&#39;s joint, or adhesive panel, of the carton. With the exception of the knock-outs, the first panel of the carton is coated on the surface facing the adhesive panel. The knock-outs are configured to align with the punch scores when the carton is assembled.  
           [0010]    In a more preferred embodiment, the adhesive panel includes a coating over the surface having the punch scores. An uncoated stripe is defined over the surface through the center of the punch scores.  
           [0011]    In a further preferred embodiment of the invention the panels are coated on both sides, with the exception of the uncoated stripe on the adhesive panel and the knock outs on the first panel. An outside coating is generally used to protect the carton from scuffs during shipping and storage. An inside coating protects from scuffing as the product contained in the carton rubs against the carton panels.  
           [0012]    The present invention also provides a method for manufacturing a carton including the steps of (a) forming a carton blank having a manufacturer&#39;s joint and a first panel, (b) forming punch scores in one of the manufacturer&#39;s joint and the first panel, (c) coating the other of the first panel and the manufacturer&#39;s joint leaving a pattern of uncoated knock outs positioned to align with the punch scores in the assembled carton, (d) folding the blank into a carton, and (e) securing the manufacturer&#39;s joint to the first panel by an adhesive disposed between the punch scores and knock outs.  
           [0013]    This invention provides a simple and inexpensive folding carton with a relatively low peel strength and a relatively high shear strength. The high shear strength resists unintended opening of the carton during shipping and storage. The low peel strength permits the carton to be easily opened by a consumer to obtain access to information printed on the interior. The punch scores also help to isolate any tearing of the panels that may occur when the carton is opened, thus preserving printed matter on the interior of the carton. Further, the peel strength and shear strength can be readily and independently varied by changing, among other things, the number, size and geometry of the uncoated knock outs, uncoated stripe and punch scores and the amount of adhesive used.  
           [0014]    These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a left side perspective view of a folding carton manufactured in accordance with a preferred embodiment of the present invention;  
         [0016]    [0016]FIG. 2 is a right side perspective view of the folding carton in a partially closed position;  
         [0017]    [0017]FIG. 3 is a perspective view of a carton blank used in the manufacture of the carton;  
         [0018]    [0018]FIG. 4 is a top plan view of a first embodiment of the carton blank,  
         [0019]    [0019]FIG. 5 is a top plan view of a second embodiment of the carton blank  
         [0020]    [0020]FIG. 6 is a bottom plan view of the second embodiment of the carton blank;  
         [0021]    [0021]FIG. 7 is a side elevational view of a portion of the carton showing the manufacturer&#39;s joint according to the first embodiment; and  
         [0022]    [0022]FIG. 8 is a side elevational view of a portion of the carton showing the manufacturer&#39;s joint according to the second embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    An easy open folding carton  1  in accordance with a preferred embodiment of the present invention is shown in FIG. 1. The carton I is a generally rectangular carton intended to contain a tube of cosmetics or other similar contents. The carton  1  generally includes a plurality of panels  11 ,  12 ,  13  and  14  that define the sidewalls of the carton I as well as dust flaps  27  (not shown),  28 ,  29  and  30  and closure flaps  25 ,  26  that define the top and bottom of the carton  1 . Instructions, product data and other information are printed on the interior of the carton  1 . The carton  1  includes a manufacturer&#39;s joint  50  that is readily opened after the contents of the carton  1  have been removed to provide access to the information printed on the interior of the carton  1 . While the present invention will be described in relation to a rectangular carton intended to contain a tube of cosmetics or other similar contents, the present invention is well suited for use with cartons of essentially any shape and for holding essentially any contents.  
         [0024]    As noted above, the carton  1  is generally rectangular defining an internal space  52  for containing one or more products. The carton  1  generally includes a right panel  11 , a front panel  12 , a left panel  13  and a back panel  14  that define the sidewalls of the container. The carton  1  further includes a pair of dust flaps  29 ,  30  and a top closure flap  26  that close the top of the carton  1  and a pair of dust flaps  27 ,  28  and a bottom closure flap  25  that close the bottom of the carton  1 . The dust flaps  27 ,  28 ,  29  and closure flaps  25 ,  26  are shown in a substantially open position, and are closed in a conventional manner. As can be seen from FIG. 2, the bottom of the carton  1  generally remains in the closed position, and the top of the carton  1  is opened to access the product housed in the carton  1 . In addition, the top of the carton  1  is generally left open after fabrication until insertion of a product into the internal space  52  of the carton  1 . Insertion of the product generally occurs in an assembly line.  
         [0025]    The panels  11 ,  12 ,  13  and  14  are arranged in a rectangular shape and are retained in this shape by an adhesive panel  15 . The adhesive panel  15  extends from the back panel  14  and is adhesively secured to the interior surface of the right panel  11 . The adhesive panel  15  includes a plurality of spaced-apart punch scores  8  (not shown). Further, the right panel  11  includes a plurality of spaced-apart knockouts  9  (not shown), which are preferably aligned with the punch scores  8 .  
         [0026]    The carton  1  will now be described in greater detail with reference to FIGS.  3 - 8 , which show the carton blank  10  used in the manufacture of the carton  1  of the preferred embodiment. FIG. 3 shows the front surface of a blank  10  for forming the carton  1 . As shown the carton  1  is preferably manufactured from a one-piece, laminated paperboard blank  10  that is folded in a conventional manner to form the carton  1 . In the preferred embodiment, the paperboard blank is manufactured from conventional paperboard materials having a thickness of approximately 0.010 to 0.024 inches. The specific paperboard will vary from application to application based primarily on the desired characteristics of the carton. In the preferred embodiment, the blank  10  has coated front and back surfaces. It is not necessary, however, for any portion of the front surface of the blank to be coated. The coating, when used, can be applied by any method known in the art for applying coatings to paperboard, such as by a printing press. The coating is preferably a UV varnish, though any of a wide variety of conventional paperboard coatings could be used. In a preferred embodiment, the front surface of the blank  10  is coated with a UV varnish and the rear surface is also coated with a UV varnish.  
         [0027]    The basic structure of a carton blank is shown in FIG. 3. The blank  10  has a top end  16  and a bottom end  17 . The blank  10  further has a right panel  11 , a front panel  12 , a left panel  13 , a back panel  14 , and an adhesive panel  15 . The right panel  11  is connected to the front panel  12  along fold line  21 . The front panel  12  is connected to the left panel  13  along fold line  22 . The left panel  13  is connected to the back panel  14  along fold line  23 . The back panel  14  is hingedly connected to the adhesive panel  15  along fold line  24 . The size, shape and configuration of the various panels can vary from application to application as desired.  
         [0028]    Further, there is a bottom closure flap  25  and a top closure flap  26  that, as noted above, close the top and bottom ends of the carton  1 . The bottom closure flap  25  is connected to the bottom end  17  of the front panel  12  along fold line  32 , and the top closure flap  26  is connected to the top end  16  of the back panel  14  along fold line  31 . In addition, the bottom closure flap  25  includes a locking tab  37  defined by fold line  39 . Similarly, the top closure flap  26  includes a locking tab  38  defined by fold line  40 . The bottom closure flap  25  and top closure flap  26  could be alternatively connected to different panels.  
         [0029]    There are also four dust flaps,  27 ,  28 ,  29  and  30  in the preferred embodiment. The dust flaps  27 ,  28 ,  29  and  30  are closed over the top and bottom ends of the carton  1  before the closure flaps  25  and  26  are closed. The top dust flaps  29  and  30  extend from the top end  16  of the right panel  11  and left panel  13 , respectively. Top dust flap  29  is connected to the right panel  11  along fold line  33 . Top dust flap  30  is connected to the left panel  13  along fold line  35 . Similarly, the bottom dust flaps  27  and  28  extend from the bottom end  17  of right panel  11  and left panel  13 , respectively. Bottom dust flap  27  is connected to right panel  11  along fold line  34  and bottom dust flap  28  is connected to left panel  13  along fold line  36 .  
         [0030]    In the preferred embodiment shown in FIG. 4, the adhesive panel  15  extends from back panel  14  and is connected thereto by fold line  24 . The adhesive panel  15  includes a number of spaced-apart punch scores  8 . These punch scores  8  can be to almost any depth in the adhesive panel  15 , but in the preferred embodiment the punch scores  8  penetrate approximately ½ the depth of the adhesive panel  15 . In the illustrated embodiment, the punch scores  8  are circular, but they can be of nearly any shape. The punch scores  8  can be created using any appropriate method in the art, such as penetrating the blank  10  with a punch. The size of the punch scores  8  will vary from application to application, keeping in mind that, with typical paperboard, adhesives and coatings, the punch scores make it easier to open the carton by facilitating separation between layers of the laminated paperboard. As a result, an increased number of punch scores or punch scores of a larger diameter will typically make it easier to open the carton. Variations in the size, shape, number and configurations of the punch scores will effect primarily the peel strength of the carton  1 . Accordingly, the characteristics of the punch scores can be altered to affect the peel strength of the carton  1  largely independent of the shear strength.  
         [0031]    In addition, FIG. 5 shows an alternate embodiment of the adhesive panel  15  in which there is an uncoated stripe  42  on the adhesive panel  15 . The uncoated stripe  42  can be any length, but in the preferred embodiment the uncoated stripe  42  runs from the top end  16  to the bottom end  17  of the adhesive panel  15  through the center of the punch scores  8 . The uncoated stripe  42  can be created using any method known in the art, such as defining the stripe on the printing plate used for applying the coating. Because coatings decrease adhesion, the size (including both width and length) of the uncoated stripe  42  will affect the ease of opening of the carton. The larger the uncoated stripe  42  is the greater the adhesion will be, and the more difficult it will be to open the carton. This will increase both the peel strength and shear strength of the carton  1 .  
         [0032]    [0032]FIG. 6 shows the back surface of the blank  10 . Differences between the back surface of the blank  10  and the front surface of the blank  10  in the preferred embodiment relate only to the adhesive panel  15  and the right panel  11 . The punch scores  8  and uncoated stripe  42  are not present on the back surface of the adhesive panel  15 . In the preferred embodiment, the back surface of the right panel  11  is coated and has a number of uncoated portions, or knock outs  9 . These knock outs  9  can be created using any appropriate method in the art, such as defining the knock outs  9  in the printing plate used for applying the coating. The knock outs  9  can be any size and shape, but are preferably approximately the same size and shape as the punch scores  8 . Since most coatings will decrease adhesion, the size of the knock outs  9  can affect both the peel and shear strength of the carton. The larger the knock outs  9 , the greater the peel and shear strength, and the more difficult it will be to open the carton. Preferably, to reduce the possibility of delamination, the knock outs  9  are no larger in diameter than the punch scores  8 .  
         [0033]    In the preferred embodiment, the number of knock outs  9  is equal to the number of punch scores  8  and the knock outs  9  are circular and slightly smaller in diameter than the punch scores  8 . As shown in FIG. 7, the knock outs  9  are preferably positioned so each knock out  9  is coincident with a punch score  8  when the front surface of the adhesive panel  15  is in contact with the back surface of the right panel  11 . Although the uncoated stripe  42  was previously described as running through the punch scores  8  on the adhesive panel  15 , it could alternatively run in a similar manner through the knock outs  9  on the right panel  11 . Regardless of which panel the uncoated stripe  42  is located on, if an uncoated stripe  42  is present it preferably runs through the center of the knock outs  9  and punch scores  8  when the right panel  11  and left panel  13  are in contact, as shown in FIG. 8.  
         [0034]    In another alternative embodiment, the knock outs  9  could be located on the adhesive panel  15  rather than the right panel  11 , and the punch scores  8  could be located on the right panel  11  rather than the adhesive panel  15  (not shown). In this alternative embodiment, the punch scores  8  and knock outs  9  remain in alignment with one another as in the preferred embodiment.  
         [0035]    The blank  10  is folded into a carton  1  using generally conventional techniques and apparatus. The left panel  13  and right panel  11  are folded 90 degrees along fold lines  22  and  21 . The back panel  14  is folded 90 degrees in the direction of right panel  11  along fold line  23 . Adhesive panel  15  is folded 90 degrees downward along fold line  24 . Adhesive panel  15  is placed inside right panel  11  so the punch scores  8  are coincident with the knock outs  9 .  
         [0036]    The adhesive panel  15  is affixed to the right panel  11  using conventional adhesives. The adhesive used is preferably a water-based adhesive, but other adhesives such as solvent-based adhesives and hot melts may also be used. In the preferred embodiment, the adhesive is a water based cold adhesive. The adhesive is preferably applied in a line extending substantially along the entire length of the adhesive panel  15 . There are many methods common in the art for applying such adhesives. For example, the adhesive can be rolled onto the adhesive panel  15  along the punch scores  8 , and the adhesive panel  15  and right panel  11  can be pressed together to bind them. This technique is generally performed during the folding process, though it can be done at any time prior to sealing. Another method is to coat the strip of the adhesive panel  15  where the punch scores  8  are located with a heat activated adhesive. The adhesive panel  15  and right panel  11  are then heated and pressed together to bind them. With this method, the adhesive is generally applied to the blank  10  prior to folding, but it can be applied at any time prior to sealing. It is known in the art that the adhesive used can be applied to the adhesive panel  15 , right panel  11 , or both as long as the adhesive will contact both the punch scores  8  and knock outs  9  when the appropriate panels are in contact. Whatever method is used, the strip of adhesive applied preferably is applied from the top to the bottom of the appropriate panel through the punch scores  8  or knock outs  9 . In addition, the strip preferably does not extend beyond the width of the punch scores  8 . However, if the strip does extend beyond the width of the punch scores  8 ., the operability of the easy-open carton will not be affected. If an uncoated stripe  42  is present, the adhesive should run the length of the uncoated stripe  42 .  
         [0037]    After the right panel  11  and adhesive panel  15  are sealed, dust flaps  28  and  30  are folded at 90 degree angles toward right panel  11  along fold lines  36  and  35  respectively. Dust flaps  27  and  29  are folded at 90 degree angles toward left panel  13  along fold lines  34  and  33  respectively. Bottom closure flap  25  is folded upward at a 90 degree angle along fold line  32  and top closure flap  26  is folded downward at a 90 degree angle along fold line  31 . The locking tab  37  of the bottom closure flap  25  is folded at a 90 degree angle toward back panel  14  along fold line  39 . The locking tab  37  of the bottom closure flap  25  is inserted into the carton  1  so the front surface of locking tab  37  is in contact with the back surface of back panel  14 . In this state, the carton  1  can be readily filled with the desired content.  
         [0038]    After the carton  1  is filled, the top of the carton  1  is closed. The locking tab  38  of the top closure flap  26  is likewise folded at a 90 degree angle toward front panel  12  along fold line  40 . The locking tab  38  of the top closure flap  26  is folded under front panel  12  so the front surface of locking tab  38  is in contact with the back surface of front panel  12 .  
         [0039]    To access the contents of the carton  1 , the top closure flap  26  and top dust flaps  29  and  30  are opened. After the contents have been removed, the carton  1  is readily unfolded to provide access to information printed on the interior of the carton. The right panel  11  is peeled away from the adhesive panel  15  along the junction between the adhesive panel  15  and the right panel  11 . The adhesive panel  15  will readily delaminate at the punch scores  8  providing less resistance to opening than would be required in the absence of the punch scores  8 .  
         [0040]    The above description is that of preferred embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.