Patent Publication Number: US-2016229615-A1

Title: Pouch container packaging and pouch container

Description:
TECHNICAL FIELD 
     The present invention relates to a pouch container packaging and also to a pouch container. 
     BACKGROUND ART 
     Pouch containers are commonly used as containers for beverages such as sports drinks and for foods such as ice cream and jelly. Patent Document 1 discloses an example of a conventional pouch container.  FIG. 13  shows a packaging for producing a pouch container disclosed in Patent Document 1. The packaging X shown in the figure includes a pair of outer films  91 , a pair of gusset films  92 , and a spout  93 . The pair of outer films  91  are disposed on the front and the back. The pair of gusset films  92  are each located in a folded state between the pair of outer films  91 . 
     To be able to hermetically hold substances, such as beverages and foods mentioned above, the packaging X has a top-edge central seal  94 , top-edge side seals  95 , side seals  96 , a bottom seal  97 , and oblique seals  98 . The top-edge central seal  94  is formed by joining the pair of outer films  91  along the top edges with the spout  93  sandwiched between protons of the top edges . The top-edge side seals  95  are formed by joining the pair of outer films  91  to the pair of gusset films  92  along the top edges. The side seals  96  are formed by joining the pair of outer films  91  to the pair of gusset films  92  along the side edges. The bottom seal  97  is formed by joining the pair of outer films  91  along the respective bottom edges. The oblique seals  98  are formed by joining the pair of outer films  91  to the pair of gusset films  92  along the oblique edges. The packaging X is such that an inner edge  96   a  of each side seal  96 , an inner edge  97   a  of the bottom seal  97 , and an inner edge  98   a  of each oblique seal  98  are substantially parallel to their outer edges and are straight throughout their length. 
     A method for producing a pouch container using a packaging X may include a leak testing step to check for leakage prior to a step of filling with an above-mentioned substance. In the leak testing step, a nozzle Nz shown in  FIG. 13  is inserted into the spout  3 , for example. Next, as shown in  FIG. 14 , air for example is blown in through the nozzle Nz instantaneously within a short period of time (two seconds or so).  FIG. 14  shows the state where the packaging X starts to inflate with the air blown in. With completion of the air blowing, the packaging X is fully inflated as shown in  FIG. 15  . The packaging X in this state is checked for air leakage. Only if no leakage is detected, the packaging X is filled with the substance. 
     Unfortunately, the leak testing step may cause an oblique seal  98  to be turned back as shown in  FIG. 15  . For the convenience of clarity in the figure, portions of the oblique seals  98  are shaded to indicate part of the outer films  91 , whereas portions of the oblique seal  98  are left unshaded to indicate part of the gusset films  92 . Among the four oblique seals  98  shown in the figure, the oblique seal  98  at the lower left is turned back so that the portion being part of the gusset film  92  is exposed on the bottom. As a result that the oblique seal  98  is turned back, the bottom seal  97  is raised. 
     After completion of the leak testing step, the interior space of the packaging X is evacuated and thus the packaging X becomes flat again. Subsequently, the step of filling the packaging with the substance is performed. An edge once turned back in the leak testing step has a crease that remains even after the packaging is flat again. As such, it often happens that the edge is unintentionally turned back again during the filling step. A pouch container having such a turned back edge involves a risk of unintentional stress applied to the bottom during, for example, a transportation step, and a consequent risk of leakage. This may undesirably result in leakage of the substance from a pouch container X despite that the pouch container is produced by using the packaging X determined to be leakage free in the leak testing step. 
     REFERENCE LIST 
     Patent Document 
     Patent Document 1: JP-A-2000-344252 
     SUMMARY 
     Problem to be Solved by Invention 
     The present invention has been conceived in view of the above circumstances and aims to provide a packaging for a pouch container as well as a pouch container capable of effectively preventing an oblique edge from turning back and reducing the risk of leakage of the substance from the pouch container. 
     Solution to Problem 
     According to a first aspect of the present invention, there is provided a packaging for a pouch container, which includes: a pair of outer films disposed on a front side and a back side with a filling-and-pouring member sandwiched at a top, where the outer films each have side edges, a bottom edge and oblique edges lying between the side edges and the bottom edge; and 
     a pair of gusset films each disposed in a folded state between the outer films and having side edges and oblique edges. The side edges of the outer films and the side edges of the gusset films are joined to provide side seals, the bottom edges of the respective outer films are joined to provide a bottom seal, and the oblique edges of the outer films and the oblique edges of the gusset films are joined to provide oblique seals. The oblique seals each have an inner edge at least a part of which is curved. 
     According to a preferred embodiment of the present invention, each oblique seal has a narrow-width portion that is narrower in width than ends of the oblique seal. 
     According to a preferred embodiment of the present invention, the inner edge of each oblique seal has a curved portion continuous with an inner edge of a side seal. 
     According to a preferred embodiment of the present invention, the inner edge of each oblique seal has a curved portion continuous with an inner edge of the bottom seal. 
     According to a preferred embodiment of the present invention, the entirety of the inner edge of each oblique seal is curved. 
     According to a second aspect of the present invention, there is provided a pouch container that includes a packaging according to the first aspect of the invention; and a substance contained in the packaging. 
     Advantages of Invention 
     According to the present invention, at least a portion of the inner edge of each oblique seal is curved. With this arrangement, the stress on the oblique seal along the entire length of the inner edge is not uniform in the longitudinal direction but varies gradually in accordance with the shape of the curve. This serves to prevent the stress on the inner edge of the oblique seal from being rapidly concentrated at the end connected to an end of the side seal and at the end connected to an end of the bottom seal, ensuring the stress to be distributed. Consequently, the oblique seals are prevented from turning back and the bottom seal is prevented from rising. Therefore, a pouch container produced by using the packaging can significantly reduce the risk of leakage of the substance as compared with a conventional pouch container. 
     Other features and advantages of the present invention will become more apparent from detailed description given below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view of a packaging according to a first embodiment of the present invention. 
         FIG. 2  is a sectional view taken along line II-II of  FIG. 1 . 
         FIG. 3  is a sectional view taken along line of  FIG. 1 . 
         FIG. 4  is a perspective view illustrating a leak testing step in a method for producing a pouch container from the packaging of  FIG. 1 . 
         FIG. 5  is a perspective view illustrating the leak testing step in the method for producing the pouch container from the packaging of  FIG. 1 . 
         FIG. 6  is a perspective view of an example of a pouch container including the packaging of  FIG. 1 . 
         FIG. 7  is a sectional view taken along line VII-VII of  FIG. 6 . 
         FIG. 8  is a partial front view of a packaging according to a second embodiment of the present invention. 
         FIG. 9  is a partial front view of a packaging according to a third embodiment of the present invention. 
         FIG. 10  is a partial front view of a packaging according to a forth embodiment of the present invention. 
         FIG. 11  is a partial front view of a packaging according to a fifth embodiment of the present invention. 
         FIG. 12( a )-( d )  is partial front views of packagings of comparative examples. 
         FIG. 13  is a perspective view illustrating an example of a method for producing a pouch container using a conventional packaging. 
         FIG. 14  is a perspective view illustrating an example of the method for producing the pouch container using the conventional packaging. 
         FIG. 15  is a perspective view illustrating an example of the method for producing the pouch container using the conventional packaging. 
     
    
    
     MODE FOR CARRYING OUT INVENTION 
     Preferred embodiments of the present invention are described below with reference to the accompanying drawings. In the description, the front of a pouch container is toward a customer when the pouch container holding the contents is placed to stand upright on a store shelve. Further, the back of the pouch container is opposite to the front, the sides are in the right and left directions, the top is in a vertically upward direction, and the bottom is in a vertically downward direction. An outer surface of each film of a pouch container refers to a surface exposed to the outside, and an inner surface refers to the opposite surface. In addition, an up-and-down direction refers to the vertical direction of the pouch container standing upright, and a width direction refers to the right-and-left direction. 
       FIGS. 1 to 3  show a packaging for a pouch container according to a first embodiment of the present invention. The packaging A 1  of the present embodiment is formed from a pair of outer films  1 , a pair of gusset films  2 , and a spout  3  so as to have a top-edge central seal  41 , four top-edge side seals  42 , four side seals  43 , a bottom seal  44 , and four oblique seals  45 .  FIG. 1  is a front view of the packaging A 1 ,  FIG. 2  is a sectional view taken along line II-II of  FIG. 1 , and  FIG. 3  is a sectional view taken along line of  FIG. 1 . 
     The pair of outer films  1  are disposed on the front and the back to sandwich the spout  3  at the top. Each outer film  1  according to the present embodiment is generally hexagonal as seen from the front and has a top edge that extends in the width direction at the top, two side edges that are spaced apart in the width direction and extend in the up-and-down direction, a bottom edge that extends in the width direction at the bottom, and two oblique edges each connecting the lower end of a side edge to the upper end of a bottom edge. 
     The pair of gusset films  2  are each located between the pair of outer films  1  in a state folded along a fold line  21 . Each gusset film  2  has a top edge, two side edges, and two oblique edges and is generally pentagonal when unfolded. In addition, the gusset film  2  has cutaway portions  22  at either end of the top edge. 
     The pair of outer films  1  and the pair of gusset films  2  are typically formed from resin films. The resin films are required to have properties expected for a packaging material, including impact resistance, abrasion resistance, and heat resistance. Typically, the seals described above are formed by heat sealing, and thus the sheets are required to have heat sealing properties suitable for that. Appropriate sheets include a multilayer sheet of a base-film layer and a sealant layer that imparts the heat sealing properties . Ina case where high gas impermeability and light-shielding characteristics are required, an appropriate multilayer sheet may be provided with a barrier layer between the base-film layer and the sealant layer. Alternatively, the base-film layer per se may be imparted with barrier characteristics. In this case, the barrier layer acts as the base-film layer, and thus the multilayer sheet includes the barrier layer and the sealant layer. 
     The following lists examples of component materials of the base-film layer, sealant layer, and gas barrier layer. 
     These layers can be stacked through a conventional lamination technique, examples of which include co-extrusion lamination, dry lamination with adhesive, thermal lamination of thermally bonding layers via a heat-sensitive adhesive layer sandwiched in between. 
     Examples of the base-film layer include single-and multi-layer films, either oriented or non-oriented, made from polyester (such as, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polycarbonate (PC)), polyolefin (such as polyethylene (PE) and polypropylene (PP)), polyamide (such as Nylon-6 and Nylon-66) , polyacrylonitrile (PAN) , polyimide (PI), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polymethyl methacrylate (PMMA), and polyethersulfone (PES). 
     Examples of the sealant layer include single-and multi-layer films, either oriented or non-oriented, made from low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ethylene-propylene copolymer (EP), cast polypropylene (CPP), bi-axially oriented nylon (ON), ethylene-olefin copolymer, ethylene acrylic acid (EAA) copolymer, ethylene-methyl methacrylate (EMMA) copolymer, and ethylene-vinyl acetate (EVA) copolymer. 
     Examples of the gas barrier layer include: a thin film of metal such as aluminum; or a film of resin such as polyvinylidene chloride (PVDC), ethylene vinyl alcohol (EVOH) copolymer and any synthetic resin (which may be the base-film layer), each film of resin having a deposited (or sputtered) layer of aluminum or inorganic oxide such as aluminum oxide or silica. 
     The outer films  1  or the gusset films  2  may be provided with a print layer (not shown) for printing of information related to the substance, including the product name, row materials, and product description, such as precautions for use, in addition to various patterns and designs. In one example, the print layer may be provided on the inner surface of the base-film layer by a known method such as gravure printing. 
     The top-edge central seal  41  is formed by heat sealing to join the pair of outer films  1  centrally along the top edges. The top-edge central seal  41  is located between the pair of gusset films  2 . In the present embodiment, the spout  3  is sandwiched at the center of the top-edge central seal  41 . The top edges of the pair of outer films  1  and the spout  3  are hermetically joined by, for example, heat sealing. 
     Each top-edge side seal  42  is formed by heat sealing to join a side end of the top edge of an outer film  1  to a side end of the top edge of a gusset film  2  . In the present embodiment, the pair of outer films  1  and the pair of gusset films  2  form four top-edge side seals  42  in total. 
     Each side seal  43  is formed by heat sealing to join a side edge of an outer film  1  to a side edge of a gusset film  2  and extends in the up-and-down direction. In the present embodiment, the pair of outer films  1  and the pair of gusset films  2  form four side seals  43  in total. 
     The bottom seal  44  is formed by heat sealing to join the pair of outer films  1  along the respective bottom edges and extends in the width direction. The bottom seal  44  is located between the pair of gusset film  2 . 
     Each oblique seal  45  is formed by heat sealing to join an oblique edge of an outer film  1  to an oblique edge of a gusset film  2 . The oblique seal  45  extends obliquely relative to both the up-and-down direction and the width direction. In the present embodiment, the pair of outer films  1  and the pair of gusset films  2  form four oblique seals  45  in total. The two oblique seals  45  located on the same side in terms of the width direction are continuous with the same widthwise end of the bottom seal  44 . 
     Each side seal  43  has an inner edge  43   a,  the bottom seal  44  has an inner edge  44   a,  and each oblique seals  45  has an inner edge  45   a.  In the present embodiment, the inner edge  43   a  is a straight line in the up-and-down direction throughout its length. The inner edge  44   a  is a straight line in the width direction throughout its length. The inner edge  45   a  is curved outward throughout its length. In other words, the inner edge  45   a  is curved at any portions, including a portion continuous with the inner edge  43   a  of the side seal  43 , a portion continuous with the inner edge  44   a  of the bottom seal  44 , and an intermediate portion located in between. In  FIG. 1 , cross-hatched portions along the inner edges  45   a  indicate curved portions of the inner edges  45   a.  In this embodiment, the entire length of each inner edges  45   a  is cross hatched. 
     Each oblique seal  45  is structured to have a smaller width W 3  around the middle than widths W 1  and W 2  at the ends. This is because the inner edge  45   a  is defined by an outward curve at least partly, and indeed entirely in the present embodiment. 
     In the present embodiment, the packaging A 1  has two sealed shoulders  46 . The sealed shoulders  46 , which are located at the intersections of the top edge with the side edges, are formed by heat sealing to join the inner surfaces of the pair of outer films  1  at portions exposed through the cutaway portions  22  in the gusset film  2 . 
     The spout  3  is a hollow member made of, for example, resin and defines a path through which the substance is poured in and out . The spout  3  has a tubular portion through which the substance is poured in and out and a boat-shaped welding portion joined to the sheet packaging body. The spout  3  is secured to the pair of outer films  1  with the boat-shaped welding portion hermetically sealed between the pair of outer films  1  at the top-edge central seal  41 . The spout  3  corresponds to a filling-and-pouring member according to the present invention. 
       FIGS. 4 and 5  show a leak testing step in a method for producing a pouch container using a packaging A 1 . Prior to this, the packaging A 1  is produced through a commonly known production method, which typically involves appropriately folding and overlaying a plurality of material sheets, and then heat sealing appropriate portions. Then, the material sheets are cut out to obtain the packaging body. Then, the boat-shaped welding portion of the spout  3  is placed between the outer films  1  at a top of the packaging body and hermetically sealed together by heat sealing. In this manner, the packagings A 1  are produced one by one. The leak testing step is performed mainly to check the heat sealed portions for any unintentional leakage. 
     First, as shown in  FIG. 4 , a nozzle Nz may be inserted into the spout  3  of the packaging A 1 . The nozzle Nz is used in the leak testing step to blow air in. As the blowing of air through the nozzle Nz starts, the pressure in the space enclosed by the pair of outer films  1  and the pair of gusset films  2  rises, causing the packaging A 1  to inflate. Eventually, the packaging A 1  is fully inflated as shown in  FIG. 5 . The blowing of air is carried out instantaneously, or within a short period of time (two seconds or so) . At this stage, none of the four oblique seals  45  are turned back, and the bottom seal  44  is in an appropriate state of lying flat along one of the outer films  1 . Once the packaging A 1  is fully inflated, the packaging A 1  is kept in the inflated state and tested for any air leakage using, for example, a sensor not shown in the figures . The test takes about two to three seconds . If leakage is detected, the packaging A 1  is rejected for use in the subsequent steps as being incapable of holding the substance. Upon completion of the leak testing step, the interior space of the packaging A 1  is evacuated within a short period of time (one second or so). As a result, the packaging A 1  becomes flat again. 
     The packaging A 1 , which is in a flat state, is subjected to the filling step using a conventionally known technique. Through this, the packaging A 1  filled with the substance Lq is obtained as a pouch container B 1  shown in  FIGS. 6 and 7 . After the substance Lq is filled, a cap  31  is attached in threaded engagement with the spout  3 . 
     Next, effects of the packaging A 1  are described. 
     The conventional packaging X often experiences a turned back edge in the leak testing step. Although the cause is not fully identified, the following is a possible explanation. In the leak testing step of the conventional packaging X shown in  FIGS. 13 to 15 , an increase in the internal pressure of the packaging X creates stress on the inner edges  96   a  of the side seals  96 , the inner edge  97   a  of the bottom seal  97 , and the inner edges  98   a  of the oblique seals  98  in accordance with the respective shapes. Each of the inner edges  96   a,    97   a,  and  98   a  is a straight line and thus subjected to a stress resulting from the force tending to push the edge outward with the edge kept straight. In other words, the stress on the inner edges  96   a,    97   a,  and  98   a  tends to be relatively uniform in the magnitude and direction substantially along the entire length except for the end portions. On the other hand, since the force is uniform substantially along the entire length, the stress tends to concentrate locally at the points of connection between the inner edges  96   a  and  98   a  and between the inner edges  97   a  and  98   a.  In addition, since air is intensively blown in within a short period of time, the relevant portions of the packaging are abruptly pushed outward. The present inventors assume that these circumstances create a force tending to locally bend the connected portions of the side seal  96  and the oblique seal  98  and of the bottom seal  97  and the oblique seal  98 . This may consequently result in that an oblique seal  98  is turned back and the bottom seal  97  is raised as shown in  FIGS. 14 and 15 . 
     Based on the above findings, each oblique seal  45  according to the present embodiment has a curved inner edge  45   a  as shown in  FIG. 1 . Thus, the stress on the inner edge  45   a  is not uniform in the longitudinal direction but varies gradually in accordance with the shape of the curve . This serves to prevent the stress on the inner edge  45   a  from being concentrated at the ends where the oblique seal  45  is connected to the side seal  43  and where the oblique seal  45  is connected to the bottom seal  44 , so that the stress is distributed. Consequently, the oblique seals  45  are prevented from turning back and the bottom seal  44  is prevented from rising. Naturally, a risk of leakage of the substance is reduced for a pouch container produced by using the packaging A 1 . 
     Each oblique seal  45  has a portion having the width W 3 , which is smaller than the width W 1  or W 2  at the end portions. That is, the inner edge  45   a  of the oblique seal  45  defines an outward curve. Through the study of the present inventors, it has been found that such an outwardly curved contour is effective to prevent occurrences of turned back edges. 
     The method for producing a pouch container may be modified to fill the packaging with the substance without performing the leak testing step. However, the filling step still involves the risk that the oblique seals  45  are turned back and the bottom seal  44  is raised. Therefore, in such a method, providing the oblique seals  45  with the inner edges  45   a  that are at least partly curved is likewise effective to prevent the oblique seals  45  from turning back and the bottom seal  44  from raising. 
       FIGS. 8 to 11  show other embodiments of the present invention. The figures use the same reference signs for the same or similar elements described in the above embodiment. Similarly to  FIG. 1 , these figures show cross-hatched portions to indicate the curved portions of the inner edges  45   a.    
       FIG. 8  shows a packaging for a pouch container according to a second embodiment of the present invention. The packaging A 2  according to the present embodiment is such that each oblique seal  45  has an inner edge  45   a  that is entirely curved. In addition, each side seal  43  has an inner edge  43   a  that is curved at a portion toward the inner edge  45   a,  and the bottom seal  44  has an inner edge  44   a  that is curved at portions toward the inner edges  45   a.  As shown in the figure, the inner edge  43   a  is seamlessly continuous with the inner edge  45   a.  In other words, the inner edge  43   a  and the inner edge  45   a  together define a curve at a connected portion. In addition, the inner edge  44   a  is seamlessly continuous with each inner edge  45   a.  In other words, the inner edge  44   a  and the inner edge  45   a  together define a curve at the connected portion. With respect to the packaging A 2  according to the present embodiment, each oblique seal  45  has a portion with the width W 3 , which is smaller than the widths W 1  and W 2  at the ends . This embodiment is effective to prevent the stress on each inner edge  45   a  from being concentrated at the ends. In addition, the present embodiment is more effective in preventing the stress on each inner edge  43   a  from being concentrated at the end toward the inner edge  45   a  and the stress on the inner edge  44   a  from being concentrated at the ends toward the respective inner edges  45   a.  Therefore, the present embodiment is appropriate to prevent the oblique seals  45  from turning back and the bottom seal  44  from raising. 
       FIG. 9  shows a packaging for a pouch container according to a third embodiment of the present invention. The packaging A 3  according to the present embodiment is such that each oblique seal  45  has an inner edge  45   a  that is curved only at an end closer to the inner edge  43   a  and straight at the other portion. In addition, the inner edge  43   a  is curved at a portion toward the inner edge  45   a  such that the inner edge  43   a  is seamlessly continuous with the inner edge  45   a.  In other words, the inner edge  43   a  and the inner edge  45   a  together define a curve at the connected portion. According to the present embodiment, each inner edge  45   a  is curved only partly but still effective to prevent stress concentration at the ends as compared with the inner edge  45   a  being entirely straight. The present embodiment is expected to be particularly effective to prevent the stress on the inner edge  45   a  from being excessively concentrated at the ends toward the inner edge  43   a.  This can prevent a force tending to locally bend the connection portions between the side seals  43  and the oblique seals  45 . Therefore, the oblique seals  45  are prevented from being turned back. 
       FIG. 10  shows a packaging for a pouch container according to a fourth embodiment of the present invention. The packaging A 4  according to the present embodiment is such that each oblique seal  45  has an inner edge  45   a  that is curved only at an end closer to the inner edge  44   a  of the bottom seal  44  and straight at the other portion. In addition, the inner edge  44   a  is curved entirely, and the inner edge  44   a  is seamlessly continuous with the inner edges  45   a.  In other words, the inner edge  44   a  and the inner edge  45   a  together define a curve at the connected portion. As stated with reference to the packaging A 3 , the partly curved inner edges  45   a  is effective to prevent stress concentration at the end thereof. The present embodiment is particularly expected to be effective to prevent the stress on the inner edge  45   a  from being concentrated at the end toward the inner edge  44   a.    
       FIG. 11  shows a packaging for a pouch container according to a fifth embodiment of the present invention. The packaging A 5  according to the present embodiment is such that each inner edge  45   a  is curved to define an outward bulge at a central portion. With such a configuration, the oblique seal  45  has the width W 3  around the middle that is significantly narrower than the widths W 1  and W 2  at the ends. The present embodiment provided with the inner edges  45   a  that are partly curved in this manner are likewise effective to prevent stress concentration at the ends thereof and thus expected to be effective to prevent the oblique seals  45  from turning back and the oblique seals  45  from raising. 
     Table 1 blow shows the results of tests conducted on the packagings A 1  to A 5  according to the present invention, the conventional packaging X shown in  FIG. 13 , and packagings C 1  to C 5  according to comparative examples shown in  FIG. 12 . In the tests, occurrences of turned back edges at the oblique seals  45  were checked. 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Packaging 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 A1 
                 A2 
                 A3 
                 A4 
                 A5 
                 X 
                 C1 
                 C2 
                 C3 
                 C4 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Occurrence 
                 21% 
                 23% 
                 25% 
                 38% 
                 31% 
                 51% 
                 73% 
                 66% 
                 58% 
                 51% 
               
               
                 of turned 
               
               
                 back edges 
               
               
                   
               
            
           
         
       
     
     The packagings A 1  to A 5  are structured as described above. The packaging X is structured as shown in  FIG. 13  to have the inner edge  45   a  of each oblique seal  45  composed only of a single straight line.  FIG. 12  shows the packagings C 1  to C 4  according to the comparative examples. As described below, the packagings C 1  to C 2  are different mainly in shape of the oblique seals  45  and common in that the inner edges  45   a  are composed of straight lines. 
     In the packaging C 1  shown in  FIG. 12( a ) , the inner edge  43   a  of the side seal  43  meets the inner edge  45   a  of the oblique seal  45  at a larger angle than in the packaging X. More specifically, the intersection between the inner edge  43   a  and the inner edge  45   a  is shifted upward. In addition, the inner edge  45   a  has a bend point. In the packaging C 2  shown in  FIG. 12( b ) , the inner edge  44   a  of the bottom seal  44  meets the inner edge  45   a  of the oblique seal  45  at a larger angle than in the packaging X. More specifically, the angle mentioned above is larger as a result that the width of the bottom seal  44  is larger. 
     In the packaging C 3  shown in  FIG. 12( c ) , the inner edge  45   a  has a bend point around the middle thereof, and the width of this middle portion is significantly smaller than the width at either end. The packaging C 4  shown in  FIG. 12( d )  has the oblique seal  45  that is narrower throughout its length than in the packaging X. 
     The test results about the occurrences of turned back edges shown in Table 1 were obtained on 50 samples of the individual packagings, namely the packagings A 1  to A 5 , X, and C 1  to C 4 . Each sample was subjected to the leak testing step to visually check the oblique seals  45  for any turned back edge. 
     As shown in Table 1, the conventional packaging X exhibited the occurrence rate of 51%, whereas the packagings A 1  to A 5  according to the present invention all exhibited the occurrence rates ranging from 21% to 38%, which are lower than the rate obtained on the packaging X. That is, the occurrences of turned back edges were reduced by providing the oblique seal  45  having an inner edge  45   a  at least partly curved. In particular, the packagings A 1 , A 2 , and A 3  respectively exhibited the occurrence rates of 21%, 23%, and 25%, each of which is about a half of the occurrence rate of the packaging X . That is , the occurrences of turned back edges were sufficiently reduced. This is assumed to be a result achieved by the inner edges  45   a  being entirely curved. In the packagings A 3  and A 4 , each inner edge  45   a  is curved only at a portion toward the bottom seal  44 . As demonstrated by the occurrence rate of 38%, these packagings still achieved the effect of reducing the occurrences of turned back edges. Comparison between the packaging A 3  and the packaging A 4  reveals that the occurrences of turned back edges were reduced more effectively by providing a curve at the connection between the inner edge  43   a  of the side seal  43  and the inner edge  45   a  of the oblique seal  45  than at the connection between the inner edge  44   a  of the bottom seal  44  and the inner edge  45   a  of the oblique seal  45 . The packaging A 5  has the inner edges  45   a  curved only at a central portion while the portions closer to the ends are straight lines. The packaging A 5  having such a structure was still effective to reduce the occurrences of turned back edges, as demonstrated by the occurrence rate of 31%. This shows that the inner edge  45   a  not curved at the ends is still effective to distribute the stress, which would otherwise be concentrated at the respective ends of the inner edge  45   a  (at the intersections with the inner edges  43   a  and  44   a ). 
     Referring now to the comparative examples C 1  to C 4 , the occurrence rates range from 51% to 73%, which are at most comparable to the occurrence rates obtained on the conventional packaging X. These results show that the occurrences of turned back edges at the oblique seal  45  cannot be reduced or may even be increased as long as the inner edges  45   a  are composed only of straight lines, regardless of the shapes and locations of the inner edges  45   a.  As set forth above, the packaging according to the present invention has an inner edge  45   a  that is at least partly curved as exemplified by the packagings A 1  to A 5  and achieves the effect of preventing the oblique seals  45  from turning back. 
     The pouch container packaging according to the present invention is not limited to the embodiments described above. Various design changes can be made to the specific structure of the packaging for a pouch container according to the present invention. 
     REFERENCE SIGNS LIST 
     
         
         A 1  to A 5  packaging 
         B 1  pouch container 
           1  outer film 
           2  gusset film 
           21  fold line 
           22  cutaway portion 
           3  spout 
           31  cap 
           41  top-edge central seal 
           42  top-edge side seal 
           43  side seal 
           43   a  inner edge 
           44  bottom seal 
           44   a  inner edge 
           45  oblique seal 
           45   a  inner edge 
           46  sealing shoulder