Patent Publication Number: US-2023158768-A1

Title: Method for manufacturing sheet material container

Description:
TECHNICAL FIELD 
     The present invention relates to a method for manufacturing a sheet material container. 
     BACKGROUND ART 
     Patent Document 1, for example, discloses a method for manufacturing a sheet material container with a structure in which a filling portion is formed that has a plurality of film layers stacked and that has a filler such as air enclosed between the layers. 
     CITATION LIST 
     Patent Document 1: Japanese Patent Publication No. 2016-525050. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a method for manufacturing a sheet material container that is configured including: one or a plurality of sheet members including a main-body forming sheet member that has an outer film layer and an inner film layer which are mutually stacked, the sheet material container being provided with: a containing region that accommodates contents, and a container body that is configured from the main-body forming sheet member and that surrounds the containing region, and the main-body forming sheet member having a main-body sealing portion, which is an attached region between the outer film layer and the inner film layer, and a non-attached region where the outer film layer and the inner film layer are partially not attached, and further having a filling portion where a filler is enclosed between the layers of the outer film layer and the inner film layer in the non-attached region, the method including: introducing gas into the containing region so as to expand the container body; and injecting the filler between the layers of the outer film layer and the inner film layer in the non-attached region in a state where the container body has been expanded. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of one preferred embodiment of a sheet material container manufactured using a method for manufacturing a sheet material container of the present invention. 
         FIG.  2    is a back view of the sheet material container illustrated in  FIG.  1   . 
         FIG.  3    is a plane view of the sheet material container illustrated in  FIG.  1    and illustrating a state with a cap portion removed. 
         FIG.  4    is a bottom view of the sheet material container illustrated in  FIG.  1   . 
         FIG.  5    is a cross-sectional view along line A-A in 
         FIG.  2   . 
         FIG.  6    is a side view of the sheet material container illustrated in  FIG.  1   . 
         FIG.  7    is an exploded perspective view illustrating an outer film layer and an inner film layer of a main-body forming sheet member. 
         FIG.  8    is an exploded perspective view illustrating an inner-bag forming sheet member and the main-body forming sheet member. 
         FIG.  9    is a plane view of a container forming sheet member, which has the inner-bag forming sheet member and the main-body forming sheet member which are mutually stacked. 
         FIG.  10    is a plane view of the sheet material container before filler is enclosed. 
         FIG.  11    is a diagram to illustrate a method for manufacturing a sheet material container according to a first embodiment and illustrating a state before performing the expanding of the container body. 
         FIG.  12    is a diagram to illustrate the method for manufacturing a sheet material container according to the first embodiment and illustrating a state in which the expanding of the container body has been performed. 
         FIG.  13    is a diagram to illustrate the method for manufacturing a sheet material container according to the first embodiment and illustrating a state in which the injecting of filler has been performed. 
         FIGS.  14 A and  14 B  are diagrams to illustrate a method for manufacturing a sheet material container according to a second embodiment, of which  FIG.  14 A  illustrates a state in which closing an external air intake hole has been performed after the expanding of the container body, and  FIG.  14 B  illustrates a state in which injecting of filler has been performed in a state where the external air intake hole is closed. 
         FIGS.  15 A and  15 B  are diagrams to illustrate a method for manufacturing a sheet material container according to a third embodiment, of which  FIG.  15 A  illustrates a state in which vacuuming via an external air intake hole is performed after the expanding of the container body, and  FIG.  15 B  illustrates a state in which injecting of filler has been performed. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     According to an investigation by the present inventors, with the manufacturing method disclosed in Patent Document 1, there is room for improvement in terms of the filling properties of the filler into the filling portion. 
     The present invention relates to a method for manufacturing a sheet material container with which the filling properties of the filler into the filling portion are favorable. 
     Preferred embodiments of the present invention will be described hereinbelow using the drawings. Note that, in all the drawings, the same reference signs are assigned to similar components, and detailed descriptions thereof will not be repeated. 
     First Embodiment 
     First, a first embodiment will be described using  FIGS.  1  to  13   . 
     A method for manufacturing a sheet material container according to this embodiment is a method for manufacturing a sheet material container  100  that is configured including one or a plurality of sheet members including a main-body forming sheet member  21  that has an outer film layer  22  and an inner film layer  23  which are mutually stacked. 
     The sheet material container  100  is configured from a containing region  17  that accommodates contents  18  ( FIG.  2   ) and a main-body forming sheet member  21 , and includes a container body  20  that surrounds the containing region  17 . 
     The main-body forming sheet member  21  has a main-body sealing portion  26 , which is an attached region between the outer film layer  22  and the inner film layer  23 , and a non-attached region  24  where the outer film layer  22  and the inner film layer  23  are partially not attached, and has a filling portion  60 , where a filler is enclosed between the layers of the outer film layer  22  and the inner film layer  23  in the non-attached region  24 . 
     The method includes introducing gas into the containing region  17  so as to expand the container body  20  (see  FIG.  12   ), and injecting the filler between the layers of the outer film layer  22  and the inner film layer  23  in the non-attached region  24  (see  FIG.  13   ) in a state where the container body  20  has been expanded. 
     According to this embodiment, the injecting of filler between the layers of the outer film layer  22  and the inner film layer  23  in the non-attached region  24  in a state where the container body  20  has been expanded is performed by causing gas to be introduced into the containing region  17  and expanding the container body  20 . Accordingly, because it is possible to suppress closing of the non-attached region  24  when filling with filler, the injection of filler can be easily performed. It is also possible to fill the containing region  17  with a sufficient amount of contents  18 . 
     In the present invention, types of contents  18  are not specifically limited. Possible contents  18  include, for example, shampoo, conditioner, body soap, detergent, bleach, softener, beverage, and food, and also include engine oil, a chemical agent, and the like. 
     In addition, the contents  18  may be a liquid (including a form of paste), or may be a solid (for example, in a form of particle (including a form of grain) or in a form of powder). 
     In the case of this embodiment, the contents  18  are, for example, a liquid. 
     If the contents  18  is a liquid, the viscosity of the contents  18  at 30° C. is, for example, preferably equal to or more than 1 mPa·s and equal to or less than 120,000 mPa·s (measured with a B-type viscometer; for example, measured using a Viscometer TV-10 or Viscometer TVB-10 manufactured by Toki Sangyo Co., or the like), and more preferably equal to or more than 1 mPa·s and equal to or less than 60,000 mPa·s. 
     The filler enclosed in the filling portion  60  may be a fluid (a gas or liquid), a solid (for example, particulate, resin pellets, or the like) or a semi-solid (for example, a foaming agent, or the like), and is preferably a gas such as air. 
     An example of the structure of the sheet material container  100  manufactured according to this embodiment is described hereinbelow using  FIGS.  1  through  10   . 
     In the case of this embodiment, the sheet material container  100  has a bottom gusset portion  13  ( FIG.  2   ,  FIG.  4   ) as the bottom part, and is capable of standing on its own in a state where the bottom gusset portion  13  is placed on a horizontal mounting surface. 
     In this embodiment, unless otherwise noted, the description of the positional relationship (vertical relationship, and so forth) of each component of the sheet material container  100  illustrates the positional relationship of the sheet material container  100  in a freestanding state as in  FIGS.  1  and  2   . However, the positional relationship in this description does not necessarily coincide with the positional relationship when the sheet material container  100  is used or manufactured. 
     The positional relationships of the various components of the sheet material container  100  illustrated in the respective drawings are sometimes also described. 
     The front surface side of the sheet material container  100  (the side away from the viewer in  FIG.  2   ) will be referred to as the front, the back side of the sheet material container  100  (the front surface side toward the viewer in  FIG.  2   ) will be referred to as the rear, the left side of the sheet material container  100  toward the front (the right side in  FIG.  2   ) will be referred to as the left, and the right side of the sheet material container  100  toward the front (the left side in  FIG.  2   ) will be referred to as the right. The left-right direction of the sheet material container  100  may also be referred to as the width direction. 
     In the case of this embodiment, the container body  20  is formed in the shape of a bag having a body portion  11 , a top gusset portion  14  disposed on the upper side of the body portion  11 , and a bottom gusset portion  13  disposed on the lower side of the body portion  11 . However, the present invention is not limited to or by this example, and the container body  20  may not have the top gusset portion  14 , or the same may not have the bottom gusset portion  13 . 
     The container body  20  surrounds the containing region  17  (surrounds an inner bag  40  in the case of this embodiment). The container body  20  forms the outer shell of the sheet material container  100 . In the following description, the body portion  11 , top gusset portion  14 , and bottom gusset portion  13  of the container body  20  may be referred to as the body portion  11 , top gusset portion  14 , and bottom gusset portion  13  of the sheet material container  100 . 
     The front shape of the body portion  11  is not specifically limited, but in the case of this embodiment, for example, as illustrated in  FIG.  2   , has a longitudinal shape with a substantially constant width dimension, and the upper edge of the body portion  11  is formed in an upwardly convex arc. 
     As illustrated in  FIG.  5   , the body portion  11  has a first main surface portion  20   a  (front panel) and a second main surface portion  20   b  (rear panel) that face each other with a containing region  17  therebetween. The first main surface portion  20   a  is located on the front surface side, and the second main surface portion  20   b  is located on the back side (see also  FIGS.  1  through  3   ). 
     The first main surface portion  20   a  is formed with left-right symmetry, for example, and the second main surface portion  20   b  is also formed with left-right symmetry, for example. Furthermore, the first main surface portion  20   a  and the second main surface portion  20   b  are formed with front-rear symmetry except for an interfacial connecting portion  65  (described subsequently) of the filling portion  60 , for example. 
     The first main surface portion  20   a  bulges frontward in a convex manner, while the second main surface portion  20   b  bulges rearward in a convex manner. 
     The container body  20  is configured by folding the main-body forming sheet member  21  (see  FIGS.  7  and  8   ) and mutually attaching the peripheral edge portions of the main-body forming sheet members  21  (in the case of this embodiment, through mutual attachment via the inner-bag forming sheet member  41  forming the inner bag  40 ). 
     The flat shape of the top gusset portion  14  is not specifically limited, but in the case of this embodiment, the top gusset portion  14  is formed in a shape in which the front-to-back width shrinks in moving from the center to the left in the width direction, and the front-to-back width shrinks in moving from the center to the right in the width direction, as illustrated in  FIG.  3   . The top gusset portion  14  is formed into a horizontal oblong shape, for example. 
     The container body  20  has a gusset periphery sealing strip  45  located along the periphery of the top gusset portion  14 , and lateral sealing strips  46  that extend up and down along the left and right edges of the body portion  11 , respectively. The gusset periphery sealing strip  45  and the lateral sealing strip  46 , for example, stand toward the outside of the container body  20 . 
     The gusset periphery sealing strip  45 , for example, circumferentially surrounds the top gusset portion  14 , except for the region where the interfacial connecting portion  65  (described subsequently) is present. 
     The gusset periphery sealing strip  45  includes a first planar portion lateral sealing strip  45   a  disposed along the boundary between the gusset (top gusset portion  14 ) and the first main surface portion  20   a , and a second planar portion lateral sealing strip  45   b  disposed along the boundary between the gusset and the second main surface portion  20   b.    
     In the case of this embodiment, the inner bag  40  is configured (see  FIG.  5   ) by mutually attaching portions of the peripheral edge portions of the inner-bag forming sheet members  41  (see  FIG.  8   ). In other words, the bag-shaped inner bag  40  is configured by bending the inner-bag forming sheet member  41  and mutually attaching the peripheral edge portions of the inner-bag forming sheet members  41 . The inner bag  40  is covered by the container body  20 . The inner bag  40  has a containing region  17  inside the inner bag  40 . 
     Thus, the sheet material container  100  has an inner bag  40  defining the containing region  17 , and the inner bag  40  is configured from an inner-bag forming sheet member  41 , which is the innermost-layer sheet member among the one or plurality of sheet members. 
     The shape of the inner bag  40  is not specifically limited. However, in the case of this embodiment, the inner bag  40  is formed into a shape similar to that of the container body  20 . 
     As illustrated in  FIG.  5   , the inner bag  40  has a first main surface portion  40   a  located on the front surface side and a second main surface portion  40   b  located on the back side, with the containing region  17  therebetween. 
     The sheet material container  100  includes, for example, a spout member  15  that is provided so as to penetrate the top gusset portion  14 , and a cap portion  70  that is attached (for example, detachably attached) to the spout member  15 . 
     More specifically, as illustrated in  FIGS.  2  and  3   , for example, the spout member  15  is configured so as to integrally include a cylindrical outlet cylinder portion  15   a  through which the contents  18  pass, and a plate-like plate shape portion  15   b  provided in an arrangement orthogonal to the axial direction at one end (lower end) in the axial direction of the outlet cylinder portion  15   a . A screw thread is formed on the outer peripheral surface of the outlet cylinder portion  15   a , and the outlet cylinder portion  15   a  has a male thread shape. The outlet cylinder portion  15   a  penetrates the top gusset portion  14  vertically and protrudes upward from the top gusset portion  14 . 
     The plate shape portion  15   b  is flanged out from the lower end of the outlet cylinder portion  15   a  toward the periphery. The planar shape of the plate shape portion  15   b  is not specifically limited, but may also be a substantially square shape, for example ( FIG.  3   ). 
     The plate shape portion  15   b  is provided, for example, on the inner or outer surface of the portion of the inner-bag forming sheet member  41  that is disposed along the top gusset portion  14  of the body portion  11 . The plate shape portion  15   b  is, for example, attached to the inner surface (lower surface) of the inner-bag forming sheet member  41  at the top gusset portion  14 . Hence, the plate shape portion  15   b  is attached to the main-body forming sheet member  21  via the inner-bag forming sheet member  41 . However, the present invention is not limited to or by this example, and the plate shape portion  15   b  may be directly attached to the inner film layer  23  of the main-body forming sheet member  21 . The attached region between the plate shape portion  15   b  and the inner-bag forming sheet member  41  circumferentially surrounds the outlet cylinder portion  15   a  in plane view. The attached region between the plate shape portion  15   b  and the inner-bag forming sheet member  41  is formed, for example, in the region overlapping the annular main-body sealing portion  26  (see  FIG.  8   ) located around the insert hole  21   a.    
     The opening  15   c  at the tip of the outlet cylinder portion  15   a  is a discharge port for discharging the contents  18  from the containing region  17 . The plate shape portion  15   b  has an opening  15   d  formed that is coaxial with the inner space of the outlet cylinder portion  15   a . The contents  18  in the containing region  17  is discharged to the outside through the openings  15   d  and  15   c.    
     Thus, the second planar portion (top gusset portion  14 ) has a discharge port (opening  15   c ) for discharging the contents  18  from the containing region  17 . 
     Furthermore, the second planar portion (top gusset portion  14 ) is provided with a plate shape portion  15   b  having an opening (opening  15   d ) that is connected to the discharge port (opening  15   c ), and the one or plurality of sheet members are attached to the plate shape portion  15   b.    
     The cap portion  70  has, for example, a mounting portion  71 , which is a female thread-shaped cylindrical portion that is detachably screwed onto the outlet cylinder portion  15   a , a pump portion  72  that is fixed to the mounting portion  71 , a dip tube  77  that extends downward from the pump portion  72 , and a head portion  73  held by the pump portion  72  that can be raised and lowered with respect to the pump portion  72 . 
     The head portion  73  has, for example, a support cylinder portion  74  that projects upward from the pump portion  72 , and a nozzle portion  75  that projects horizontally from the upper end of the head portion  73 , and a discharge port  76  for discharging the contents  18  is formed at the tip of the nozzle portion  75 . 
     The flow path (not shown in the drawings) of the contents  18  in the cap portion  70  is arranged so as to penetrate the openings  15   d  and  15   c  vertically. 
     When the head portion  73  is pushed (depressed) against the pump portion  72 , the contents  18  are discharged from the discharge port  76  by the action of the pump portion  72 . 
     In the case of this embodiment, the filling portion  60  includes, for example, a first filling portion  61  formed circumferentially along the peripheral edge portion of the first main surface portion  20   a , a second filling portion  62  formed circumferentially along the peripheral edge portion of the second main surface portion  20   b , a third filling portion  63  ( FIG.  4   ) formed circumferentially along the peripheral edge portion of the bottom gusset portion  13 , and a fourth filling portion  64  ( FIG.  3   ) formed circumferentially around the outlet cylinder portion  15   a  in the top gusset portion  14 , as illustrated in  FIGS.  1  to  6   . 
     The lower edge of the first filling portion  61  is connected to the front edge of the third filling portion  63 , the lower edge of the second filling portion  62  is connected to the rear edge of the third filling portion  63 , and the center of the top edge of the first filling portion  61  in the horizontal width direction is connected to the center of the front edge of the fourth filling portion  64  in the horizontal width direction. 
     The sheet material container  100  includes a filling portion  60  with such a structure, thereby securing sufficient structural strength over almost the entire container body  20 . 
     In the case of this embodiment, the entire filling portion  60  is formed in an integrated manner. 
     Note that, in the present invention, the sheet material container  100  may include a plurality of filling portions  60  that are independent of each other. 
     Here, the connecting portion between the first filling portion  61  and the fourth filling portion  64 , the connecting portion between the first filling portion  61  and the third filling portion  63 , and the connecting portion between the second filling portion  62  and the third filling portion  63  are interfacial connecting portions  65 , respectively. 
     In the case of this embodiment, the container body  20  has a body portion  11  and a top portion (top gusset portion  14 ), and one main surface portion of the body portion  11  (the first main surface portion  20   a ) is the first planar portion, and the top portion is the second planar portion. 
     Further, the filling portion  60  has a first filling portion  61  formed along the peripheral edge portion of the main surface portion (first main surface portion  20   a ) and a fourth filling portion  64  formed around the discharge port in the top portion (top gusset portion  14 ), and the first filling portion  61  and the fourth filling portion  64  are connected via the interfacial connecting portion  65 . 
     Moreover, in the case of this embodiment, the container body  20  has a body portion  11  and a bottom portion (bottom gusset portion  13 ). One main surface portion of the body portion  11  (first main surface portion  20   a ) is the first planar portion, and the bottom portion (bottom gusset portion  13 ) is also the second planar portion. 
     Further, the filling portion  60  has a first filling portion  61  formed along the peripheral edge portion of the main surface portion (first main surface portion  20   a ) and a third filling portion  63  formed along the peripheral edge portion of the bottom portion (bottom gusset portion  13 ), and the first filling portion  61  and the third filling portion  63  are connected via an interfacial connecting portion  65 . 
     Furthermore, in this embodiment, the other main surface portion of the body portion  11  (second main surface portion  20   b ) and the bottom portion (bottom gusset portion  13 ) also have a relationship with the first and second planar portions. 
     Thus, the plurality of planar portions that the container body  20  has include a first planar portion and a second planar portion that are adjacent to each other, and the filling portion  60  includes an interfacial connecting portion  65  that is disposed so as to straddle the first planar portion and the second planar portion across the boundary between the first planar portion and the second planar portion. 
     As illustrated in  FIGS.  7  and  8   , the main-body forming sheet member  21  is configured by mutually stacking and attaching the outer film layer  22 , which forms the outer side of the container body  20 , and the inner film layer  23 , which forms the inner side of the container body  20 . That is, as an example, in the case of this embodiment, the main-body forming sheet member  21  is configured from two film layers, namely the outer film layer  22  and the inner film layer  23 . However, the present invention is not limited to or by this example, and the main-body forming sheet member  21  may have film layers other than the outer film layer  22  and the inner film layer  23 . 
     In the case of this embodiment, the outer film layer  22  and the inner film layer  23  are formed in the same shape as each other. However, the present invention is not limited to or by this example, and the outer film layer  22  and the inner film layer  23  may be mutually different shapes. When different shapes, the outer film layer  22  preferably has a larger shape than the inner film layer  23 . 
     An insert hole through which the outlet cylinder portion  15   a  of the spout member  15  is inserted is formed in the outer film layer  22  and the inner film layer  23 . 
     The main-body forming sheet member  21  has a non-attached region  24  ( FIG.  8   ) where the outer film layer  22  and the inner film layer  23  are partially not attached. For example, in one or both of the outer film layer  22  and the inner film layer  23 , the surface facing the other is subjected to a partial non-attaching treatment. The non-attaching treatment can be easily formed by applying a non-attaching agent (a so-called adhesion inhibiting agent) to establish an adhesion inhibiting state. For the adhesion inhibiting agent, any adhesion inhibiting agent may be used as long as the same is capable of suppressing the attachment between the outer film layer  22  and the inner film layer  23 . For the adhesion inhibiting agent, it is possible to preferably use, for example, printing ink, medium ink, ink dedicated to adhesion inhibition, or the like, which is used in offset printing, flexographic printing, and letterpress printing (relief printing). In addition, thermosetting ink or UV curable ink can be preferably used. The range in which the non-attaching treatment is applied is the non-attached region  24 . A filler is enclosed in the non-attached region  24  to form the filling portion  60 . 
     The filling portion  60  is not necessarily limited to being formed over the entire non-attached region  24 , and may be formed in a portion of the non-attached region  24 . 
     In  FIG.  7   , in each of the outer film layer  22  and the inner film layer  23 , the regions that are mutually attached to form the main-body sealing portion  26  are hatched right side up for convenience. 
     In  FIGS.  8  and  9   , in the main-body forming sheet member  21 , the region where the outer film layer  22  and the inner film layer  23  are mutually attached to define the non-attached region  24 , that is, the region where the main-body sealing portion  26  is formed, is hatched right side up for convenience. 
     Furthermore, in  FIG.  8   , the seal boundary line  21   c , which is the boundary line between the sealing region of the peripheral edge portion of the main-body forming sheet member  21  and other regions, is illustrated as a double-dotted chain line. In the case of this embodiment, in the region outside the seal boundary line  21   c  of the main-body forming sheet member  21 , the outer film layer  22  and the inner film layer  23  are mutually attached during bag making, and the inner film layer  23  and the inner-bag forming sheet member  41  are mutually attached. 
     As an example, heat sealing, ultrasonic sealing, adhesive attaching, or the like, may be used as a method of attaching the outer film layer  22  and the inner film layer  23 . 
     Furthermore, as illustrated in  FIGS.  2 ,  7 ,  8  and  9   , the outer film layer  22  and the inner film layer  23  of the main-body forming sheet member  21  have external air intake holes  96  and  97  through which air (external air) is taken in, between the container body  20  and the inner bag  40 . The external air intake hole  96  is formed in the outer film layer  22 , and the external air intake hole  97  is formed in the inner film layer  23 . The external air intake holes  96  and  97  are located in mutually different positions, for example. As an example, as illustrated in  FIG.  2   , the external air intake hole  96  is located at the bottom of the second main surface portion  20   b  of the container body  20 , and the external air intake hole  97  is located at the top of the second main surface portion  20   b  of the container body  20 . 
     Thus, the sheet material container  100  has an inner bag  40  defining the containing region  17 , the inner bag  40  being covered by the container body  20 , and the main-body forming sheet member  21  has the external air intake holes  96 ,  97 , through which external air is taken in, in the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20 . 
     In the case of this embodiment, each of the outer film layer  22  and the inner film layer  23  has a layered structure that includes a plurality of resin layers. The inner-bag forming sheet member  41  also has a layered structure that includes a plurality of resin layers. 
     The main-body forming sheet member  21  preferably includes a resin layer of one of the following types: polyethylene, polypropylene, polyester, and polyamide. 
     The materials of the resin layers forming the outer film layer  22  and the inner film layer  23  of the main-body forming sheet member  21  are not specifically limited, but include, for example, polyethylene materials such as high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-low density polyethylene (ULDPE), and ethylene-vinyl alcohol copolymer (EVOH), or polypropylene materials such as oriented polypropylene (OPP), unoriented polypropylene (CPP), isotactic PP, syndiotactic PP, atactic PP, random PP, and block PP, or polyester materials such as polyethylene terephthalate (PET), amorphous polyethylene terephthalate (amorphous PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polybutylene naphthalate (PBN), or polyamide materials such as oriented nylon (ONy), unoriented nylon (CNy), nylon 6, nylon 66, nylon 11, nylon 12, and MXD6. Of these, the foregoing polyethylene-based materials are particularly preferable. 
     The outer film layer  22  has, as an example, a four-layer structure configured by stacking four resin layers, namely the first layer, the second layer, the third layer, and the fourth layer, in that order. 
     The first of these layers forms the outer surface of the container body  20 . The first layer is composed of polyethylene terephthalate (PET) or oriented nylon (ONy), for example. Examples of the main function of the first layer include providing the container body  20  with a feeling of gloss and printability, and also securing rigidity for the container body  20 . 
     The second layer is, for example, a layer of transparent deposition PET including polyethylene terephthalate obtained through vapor deposition of silica and/or alumina on the surface of this second layer on the first layer side. Examples of the main function of the second layer include providing the container body  20  with a gas barrier property. 
     The third layer is composed of oriented nylon, for example. Examples of the main function of the third layer include securing pinhole resistance for the container body  20 . 
     The fourth layer is composed of linear low-density polyethylene (LLDPE), for example. Examples of the main function of the fourth layer include securing a heat seal property with the inner film layer  23 . 
     Examples of the layer structure of the inner film layer  23  include a structure that includes a fifth layer composed of linear low-density polyethylene (LLDPE), for example, in addition to the same layer structure as the first through fourth layers of the outer film layer  22 . The fifth layer is adjacent to the first layer and forms the surface on the opposite side to the fourth layer in the inner film layer  23 . Examples of the main function of the fifth layer include securing a heat seal property with the outer film layer  22 . 
     Examples of the main function of the fourth layer of the inner film layer  23  include securing a heat seal property with the inner-bag forming sheet member  41 . 
     However, the layer structure of the outer film layer  22  and the inner film layer  23  is not limited to or by the foregoing examples, nor are the materials of each layer forming the outer film layer  22  and the inner film layer  23  limited to or by the foregoing examples. 
     As one example, the inner-bag forming sheet member  41  that forms the inner bag  40  has a three-layer structure configured by stacking a first layer, a second layer, and a third layer in this order. 
     Of these layers, the first layer is composed of linear low-density polyethylene, for example. Examples of the main function of the first layer include securing a heat seal property with the main-body forming sheet member  21  (a heat seal property with the inner film layer  23 ). 
     The second layer is, for example, a layer of transparent deposition oriented nylon composed of oriented nylon obtained through vapor deposition of silica and/or alumina on the surface of this second layer on the first layer side. Examples of the main function of the second layer include securing a gas barrier property and pinhole resistance. 
     The third layer is composed of linear low-density polyethylene, for example. Examples of the main function of the third layer include securing a heat seal property between inner-bag forming sheet members  41 . 
     Note that the layer structure of the inner-bag forming sheet member  41  is not limited to or by the structure that has been described here. 
     As illustrated in  FIGS.  8  and  9   , the inner-bag forming sheet member  41  is stacked on the main-body forming sheet member  21 . As illustrated in  FIG.  9   , the peripheral edge portion of the inner film layer  23  and the peripheral edge portion of the inner-bag forming sheet member  41  are mutually attached, and the peripheral edge portion of the outer film layer  22  and the peripheral edge portion of the inner film layer  23  are mutually attached. As a result, the container forming sheet member  51  is configured from the main-body forming sheet member  21  and the inner-bag forming sheet member  41 . 
     Here, the sealing portion of the peripheral edge portion of the container forming sheet member  51  is referred to as the periphery sealing portion  52 . The periphery sealing portion  52  includes a sealing portion between the peripheral edge portion of the inner film layer  23  and the peripheral edge portion of the inner-bag forming sheet member  41  (hereinafter referred to as the inner/outer sealing portion  43 ), and a sealing portion between the peripheral edge portion of the outer film layer  22  and the peripheral edge portion of the inner film layer  23  (hereinafter referred to as the main-body periphery sealing portion  28 ). 
     In  FIG.  9   , the region where the periphery sealing portion  52  is formed is marked with left-up hatching. Furthermore, in  FIG.  9   , in the region where the formation region of the periphery sealing portion  52  overlaps the formation region of the main-body sealing portion  26 , the left-up hatching overlaps the right-up hatching. 
     As an example, heat sealing, ultrasonic sealing, adhesive attaching, or the like, may be used as a method for forming the periphery sealing portion  52 . 
     As illustrated in  FIG.  9   , the main-body forming sheet member  21  has, for example, a first sheet portion  31 , which is a portion that forms the first main surface portion  20   a , a second sheet portion  32 , which is the portion that forms the second main surface portion  20   b , a bottom-gusset forming sheet portion  38 , which is the portion that forms the bottom gusset portion  13 , a top-gusset forming sheet portion  39 , which is the portion that forms the top gusset portion  14 , and the tubular extending portion  25 . The extending portion  25  extends outward from the second sheet portion  32 , for example. 
     The top gusset forming sheet portion  39  has an insert hole  21   a  through which the outlet cylinder portion  15   a  of the spout member  15  is inserted. 
     In the case of this embodiment, the non-attached region  24  is formed in a shape corresponding to the shape of the filling portion  60  of the sheet material container  100 . 
     In the non-attached region  24 , the portion  24   b  that becomes the fourth filling portion  64  is formed in a circumferential shape around the insert hole  21   a , for example, as illustrated in  FIG.  9   . More specifically, for example, the outer edge (outline) of the portion  24   b  is smaller than the outline of the top-gusset forming sheet portion  39 , and the inner edge of the portion  24   b  is circular, which is larger than the insert hole  21   a.    
     In the case of this embodiment, the inner-bag forming sheet member  41  is formed in the same shape as the portion of the main-body forming sheet member  21  excluding the extending portion  25 . 
     Note that, in  FIG.  8   , the seal boundary line  41   a  of the inner-bag forming sheet member  41  is illustrated using a double-dotted chain line for convenience. The seal boundary line  41   a  is a boundary line between the region where the inner-bag forming sheet member  41  is attached (sealed) with the main-body forming sheet member  21  and other regions in the inner-bag forming sheet member  41 , and also between the region where the inner-bag forming sheet members  41  are attached together when the container forming sheet member  51  is used to form the sheet material container  100  and other regions in the inner-bag forming sheet member  41 . 
     In the case of this embodiment, the position of the seal boundary line  41   a  and the position of the seal boundary line  21   c  correspond to each other (overlap each other). 
     In the inner-bag forming sheet member  41 , an insert hole  41   b , through which the outlet cylinder portion  15   a  of the spout member  15  is inserted, is formed in the portion overlapping the top-gusset forming sheet portion  39 . 
     The plate shape portion  15   b  of the spout member  15  is, for example, attached against the inner surface of the portion overlapping the top-gusset forming sheet portion  39  in the inner-bag forming sheet member  41 . The outlet cylinder portion  15   a  is caused to pass through the insert hole  41   b  of the inner-bag forming sheet member  41  and the insert hole  21   a  of the top-gusset forming sheet portion  39 , and protrudes toward the outer surface side of these sheets. 
     In a state where the container forming sheet member  51  is valley-folded at the bending line  81 , the bending line  82 , and the bending line  84  illustrated in  FIG.  9   , and where the container forming sheet member  51  is mountain-folded at the bending line  83  and the bending line  85 , the peripheral edge portions of the container forming sheet member  51  (the inner-bag forming sheet members  41 ) are attached to each other, whereby the container forming sheet member  51  is formed into a double-structured bag. Here, a valley fold is a convex fold toward the back in  FIG.  9   , and a mountain fold is a convex fold toward the front in  FIG.  9   . 
     In other words, the edges of the inner-bag forming sheet members  41  are attached together to form the inner-bag sealing portion  42  (see  FIG.  1   ), the inner bag  40  thus being formed by the inner-bag forming sheet members  41  and thereby forming the bag-shaped container body  20  that covers the inner bag  40 . 
     As an example, heat sealing, ultrasonic sealing, adhesive attaching, or the like, may be used as a method of attaching the inner-bag forming sheet members  41  together. 
     In the case of this embodiment, the main-body periphery sealing portion  28 , the inner-bag sealing portion  42 , and the inner/outer sealing portion  43  are located in positions so as to correspond to each other (in mutually overlapping positions). The main-body periphery sealing portion  28 , the inner-bag sealing portion  42 , and the inner/outer sealing portion  43  are collectively referred to as the periphery sealing portion  19  (the periphery sealing portion  19  includes the main-body periphery sealing portion  28 , the inner-bag sealing portion  42 , and the inner/outer sealing portion  43 ). 
     For this reason, in the case of this embodiment, the gusset periphery sealing strip  45  and the lateral sealing strip  46  are each configured to include the main-body periphery sealing portion  28 , the inner-bag sealing portion  42  and the inner/outer sealing portion  43 . 
     However, the present invention is not limited to or by this example, and the gusset periphery sealing strip  45  and the lateral sealing strip  46  may also be configured from only the main-body periphery sealing portion  28 . 
     In the first sheet portion  31 , the portion on the top-gusset forming sheet portion  39  side from the bending line  85  is the first overlapping portion  31   a . The first overlapping portion  31   a  is disposed overlapping one half in the top-gusset forming sheet portion  39  in a state before the non-attached region  24  is filled with the filler. 
     The portion of the second sheet portion  32  that is located farther from the bottom-gusset forming sheet portion  38  than the bending line  86  is the second overlapping portion  32   a . The second overlapping portion  32   a  is disposed overlapping the other half in the top-gusset forming sheet portion  39  in a state before the non-attached region  24  is filled with the filler. 
     Thus, as illustrated in  FIG.  10   , the container forming sheet member  51  is formed into a double bag shape to obtain the sheet material container  100 . In the state illustrated in  FIG.  10   , the sheet material container  100  has a flat shape because the containing region  17  has not yet been expanded and the filling portion  60  has not been filled with filler. 
     Thus, the sheet material container  100  has a periphery sealing portion  19  in which one or a plurality of sheet members are bent along the bending lines  81  to  86  and in which portions of the peripheral edge portions of at least an innermost-layer sheet member (the inner-bag forming sheet member  41 ) among the one or plurality of sheet members are mutually attached. The container body  20  includes a plurality of planar portions. In the case of this embodiment, the container body  20  has four planar portions, namely the first main surface portion  20   a , the second main surface portion  20   b , the top gusset portion  14 , and the bottom gusset portion  13 . 
     In the sheet material container  100 , for example, the filler is injected into the non-attached region  24  from the injection port  25   a  ( FIG.  10   ) formed in the extending portion  25 , and then the non-attached region  24  is sealed at the portion connected to the base end of the extending portion  25 . The filler is thus enclosed in the non-attached region  24  (filling portion  60 ). 
     Note that the pressure within the filling portion  60  is not specifically limited. However, it is preferable that this pressure is higher than atmospheric pressure, and for example, may be set to be equal to or more than 10 kPa and equal to or less than 500 kPa (gauge pressure). 
     After the filler has been enclosed in the filling portion  60 , for example, the extending portion  25  is cut away. 
     In this way, a sheet material container  100  (see  FIGS.  1  to  6   ) is obtained with the filler enclosed in the filling portion  60 . However, the extending portion  25  may remain uncut even in the state of the sheet material container  100  in which the filler is enclosed. 
     After making the sheet material container  100 , the contents  18  are filled into the containing region  17  through the outlet cylinder portion  15   a  of the spout member  15 , and then the cap portion  70  is mounted on the spout member  15  to obtain the sheet material container  100  with the contents  18  enclosed in the containing region  17 . 
     The injecting of filler into the filling portion  60  will be described hereinbelow in more detail using  FIGS.  11  through  13   . Note that  FIGS.  11  to  13    illustrate the structure of the sheet material container  100  as viewed from the side (left side). 
     First, the sheet material container  100  is placed in the manufacturing apparatus illustrated in  FIG.  11   . 
     This manufacturing apparatus includes, for example, a gas supply source  420  for supplying gas (for example, air) and a first gas supply piping  421  for supplying gas from the gas supply source  420  to the containing region  17  (see  FIG.  5   ). The first gas supply piping  421  has, for example, a first regulator  422  located near the gas supply source  420 , a first switch valve  461  located downstream of the first regulator  422 , a first speed controller  462  (flow speed control valve) located downstream of the first switch valve  461 , a stopper member  430  that closes the tip of the spout member  15 , and a first valve  424  located between the first regulator  422  and the gas supply source  420 . The stopper member  430  may be a cap member that closes the tip of the spout member  15 , a rubber stopper, or packing. The tip of the first gas supply piping  421  penetrates the stopper member  430  and is held by the stopper member  430 , and is inserted into the inside of the outlet cylinder portion  15   a  of the spout member  15  or into the containing region  17 . The tip of the first gas supply piping  421  is a gas supply port  467  that supplies gas to the containing region  17 . In other words, the gas supply port  467  is provided to the stopper member  430 . The first gas supply piping  421  has, for example, a first branch piping  421   a  branching in the vicinity of the stopper member  430 , and the first branch piping  421   a  is provided with a first pressure gauge  423 . Note that the order of arrangement of each component in the first gas supply piping  421  is not limited to or by the foregoing example, and any other order may be used as long as the operation described subsequently can be realized. 
     The manufacturing apparatus is further provided with, for example, a second gas supply piping  425  for supplying gas from the gas supply source  420  into the filling portion  60 , a holding member  440  for holding the outlet cylinder portion  15   a  of the spout member  15 , and a first holding block  452  and a second holding block  453  for sandwiching the extending portion  25 . The second gas supply piping  425  has, for example, a second regulator  426 , a second switch valve  463  located downstream of the second regulator  426 , a second speed controller  464  (flow speed control valve) located downstream of the second switch valve  463 , and a second valve  427  located between the second regulator  426  and the gas supply source  420 . The tip  425   a  of the second gas supply piping  425  is buried, for example, in the first holding block  452 . The second gas supply piping  425  has, for example, a second branch piping  425   b  branching off in the vicinity of the first holding block  452 , and a second pressure gauge  465  is provided to the second branch piping  425   b . Note that the order in which the components are arranged in the second gas supply piping  425  is not limited to or by the foregoing example, rather, any other order may be used as long as the operation described subsequently can be realized. 
     By holding the outlet cylinder portion  15   a  of the spout member  15  by using the holding member  440 , sandwiching the extending portion  25  between the first holding block  452  and the second holding block  453 , and mounting the stopper member  430  on the spout member  15 , the sheet material container  100  is placed in the manufacturing apparatus. 
     In this state, the tip of the spout member  15  is closed by the stopper member  430 . The distal end of the tip  425   a  of the second gas supply piping  425  is located at a position corresponding to the injection port  25   a  of the extending portion  25 . 
     After placing the sheet material container  100  in the manufacturing apparatus, the introducing of gas into the containing region  17  and expanding the container body  20  (see  FIG.  12   ), and the injecting of the filler between the layers of the outer film layer  22  and the inner film layer  23  in the non-attached region  24  in a state where the container body  20  has been expanded (see  FIG.  13   ), are performed. 
     The sheet material container  100  in this embodiment enters a state of being bent along the bending lines  81  to  86 , as illustrated in  FIG.  10   . When filling with filler is attempted in this state, the portion intersecting the bending lines  81 ,  82 , and  84  (interfacial connecting portion  65 ) in the non-attached region  24  and the portion intersecting the bending line  83  in the non-attached region  24  tend to be blocked, which is likely to prevent smooth distribution of the filler. In contrast, by providing the expanding of the container body  20  as per this embodiment, and injecting the filler in a state where the container body  20  has been expanded, blockage of the non-attached region  24  (blockage of the interfacial connecting portion  65 ) during the filling with the filler can be suppressed, thereby facilitating the injection of the filler. Moreover, it is also possible to fill the containing region  17  with a sufficient amount of contents  18 , and the reproducibility of the volume (full volume) of the containing region  17  becomes favorable. 
     Here, the state in which the container body  20  has been expanded is different from the state in which the sheet material container  100  is bent and there is practically no gas present in the containing region  17  ( FIG.  10   ), and in a state in which gas is introduced into the containing region  17  to a certain extent, the pressure in the containing region  17  in a state where the container body  20  has been expanded may be either in a positive pressure state or an atmospheric pressure state. 
     In particular, in a sheet material container  100  having an inner bag  40  as this embodiment, because the introducing of gas into the containing region  17  and expanding the container body  20  are provided, wrinkles formed in the inner bag  40  are reduced when the inner bag  40  is filled with the contents  18 , thus resulting in a good appearance. 
     More specifically, for example, when the manufacturing apparatus is operating, the first valve  424  is always open, and by opening the first switch valve  461 , gas can be supplied from the gas supply source  420  into the containing region  17  to expand the container body  20 , as illustrated in  FIG.  12   . In other words, in the case of this embodiment, expanding of the container body  20  is performed by blowing gas into the containing region  17 . 
     By expanding the container body  20 , there is a transition from a state where the first sheet portion  31 , which is the portion that forms the first main surface portion  20   a , and the second sheet portion  32 , which is the portion that forms the second main surface portion  20   b , are in close proximity as illustrated in  FIG.  11   , to a state where the first sheet portion  31  and the second sheet portion  32  are sufficiently separated and the bottom gusset portion  13  is developed, as illustrated in  FIG.  12   . In other words, the angle with which the portions along each bending line  81 ,  82 ,  83 ,  84  ( FIG.  10   ) of the container forming sheet member  51  are folded becomes less acute. More specifically, in the state in  FIG.  11   , the container forming sheet member  51  is folded back by about 180 degrees at the portions along each of the bending lines  81 ,  82 ,  83 ,  84 , and the portions of the container forming sheet member  51  on both sides of the bending lines  81 ,  82 ,  83 , and  84  therebetween are substantially in close contact or face-to-face contact. In contrast, in the state in  FIG.  12   , the portions of the container forming sheet member  51  on both sides of the bending lines  81 ,  82 ,  83 , and  84  are separated from each other, and the angle therebetween is widened (for example, widened to about 90 degrees). 
     Thus, the sheet material container  100  has a mouth portion (for example, an opening at the tip of the spout member  15 ) with which the contents are poured out from the containing region  17 , and the expanding of the container body  20  is preferably performed by closing the mouth portion using a stopper member  430  and blowing gas into the containing region  17  from the gas supply port  467  provided to the stopper member  430 . The filling of the containing region  17  with gas can accordingly be performed favorably. 
     Furthermore, in the expanding of the container body  20 , when the internal pressure of the first regulator  422  (the setting value of the first regulator  422 ) is set high in order to increase the flow rate of the gas when the mouth portion is plugged using the stopper member  430 , rupture of the container body  20  or the inner bag  40  is likely to occur. In such a case, the rupture of the container body  20  or the inner bag  40  can be suppressed by not completely closing the mouth portion with the stopper member  430 , and providing a slight gap between the mouth portion and the stopper member  430  to intentionally allow the supplied gas to leak. 
     Further, when the manufacturing apparatus is operating, the second valve  427  is always open. Next, by opening the second switch valve  463 , gas can be injected from the gas supply source  420  through the second gas supply piping  425  into the filling portion  60  from the injection port  25   a  of the extending portion  25 . The filling portion  60  thus expands, as illustrated in  FIG.  13   . 
     Next, sealing of the filling portion  60 , that is, sealing of the non-attached region  24 , for example, at the portion that connects to the base end of the extending portion  25 , is performed. 
     Here, in the case of this embodiment, for example, expanding of the container body  20  is performed in a state where the peripheral edge portions of the foregoing one or plurality of sheet members are not attached at a portion in the extending direction of the periphery sealing portion  19 . 
     More specifically, for example, the position of the main-body forming sheet member  21  that overlaps the point where the extending portion  25  is formed is non-attached. More specifically, the position in which the main-body forming sheet member  21  overlaps the base end of the extending portion  25  is non-attached. 
     In addition, the expanding of the container body  20  is carried out in a state where the position in which the main-body forming sheet member  21  overlaps the part where the extending portion  25  is formed is non-attached. In other words, an extending portion  25  that extends outwardly is formed on the main-body forming sheet member  21 , and the extending portion  25  has an injection port  25   a  with which the filler is injected, and in the position of overlapping with the extending portion  25  (at the stage of performing the expanding of the container body  20 ), the peripheral edge portions of the foregoing one or plurality of sheet members are not attached. 
     Using this structure of the sheet material container  100 , when the container body  20  is expanded by blowing gas into the containing region  17 , the concentration of stress on the periphery sealing portion  19  can be suppressed. 
     In particular, when the expanding of the container body  20  is performed in a state where the mouth portion is plugged with the stopper member  430 , setting the internal pressure of the regulator high to increase the flow rate will likely cause the container body  20  or inner bag  40  to rupture. However, by partially not attaching the peripheral edge portions of one or a plurality of sheet members, the load on the periphery sealing portion does not become too large, and rupture of the container body  20  or inner bag  40  can be suppressed. 
     Moreover, because the points at which the peripheral edge portions of the one or plurality of sheet members are not attached are formed in a position overlapping the extending portion  25 , the points at which there is non-attachment at the same time as the filling portion  60  is sealed can be attached in the sealing of the filling portion  60 . In other words, the method for manufacturing a sheet material container according to this embodiment includes: sealing of the filling portion  60  after the injecting of the filler, wherein, in the sealing of the filling portion  60 , the points at which the peripheral edge portions of the one or plurality of sheet members are not attached are attached at the same time as the filling portion  60  is sealed. 
     Here, when injecting gas into the filling portion  60 , the inside of the containing region  17  is preferably held at a higher pressure than atmospheric pressure by the pressure of the gas supplied to the containing region  17  from the gas supply source  420  via the first gas supply piping  421 . In other words, it is preferable to perform the injecting of the filler while holding the inside of the containing region  17  in a positive pressure state. Because the formation of wrinkles in the filling portion  60  can accordingly be suppressed, a filling portion  60  that is difficult to buckle can be formed, and the sheet material container  100  can be afforded a favorable appearance. 
     By setting the setting value of the first regulator  422  so that the indicated value of the first pressure gauge  423  is greater than atmospheric pressure, the inside of the containing region  17  can be held in a positive pressure state. 
     By way of an example, the setting value of the first regulator  422  is set so that the difference between the indicated value of the first pressure gauge  423  and atmospheric pressure is equal to or more than 0.1 kPa and equal to or less than 500 kPa. In other words, the difference between the pressure of the containing region  17  in the foregoing positive pressure state and atmospheric pressure is preferably equal to or more than 0.1 kPa and equal to or less than 500 kPa. 
     The setting value of the first regulator  422  is preferably set at equal to or more than 1 kPa and equal to or less than 1000 kPa. That is, in the expanding of the container body  20 , it is preferable to set the set gauge pressure of the regulator (first regulator  422 ) on the supply source side to equal to or more than 1 kPa and equal to or less than 1000 kPa when supplying the gas from the supply source (gas supply source  420 ) to the containing region  17 . 
     Further, it is preferable to use the first regulator  422  or the first speed controller  462  to blow the gas into the containing region  17  while gradually reducing the flow rate of the gas. In this way, the load on the containing region  17  and so forth of the sheet material container  100  can be suppressed. 
     Here, the gas flow rate may be reduced continuously or may be reduced in steps. 
     Further, it is preferable to use the second regulator  426  or the second speed controller  464  to perform the injecting of the filler while gradually reducing the flow rate of the filler. In this way, the load on the filling portion  60  and so forth of the sheet material container  100  can be suppressed. 
     Here, the flow rate of the filler may be reduced continuously or may be reduced in steps. 
     The sealing of the filling portion is preferably performed after a positive pressure state inside the containing region  17  is released. In other words, it is preferable to perform the sealing of the filling portion after restoring the inside of the containing region  17  to atmospheric pressure, or at a low pressure close to atmospheric pressure. In this way, the injection pressure of the filler (for example, air) into the filling portion  60  can be easily controlled. Methods for releasing the positive pressure state include, but are not limited to, closing the first valve  424 , or setting the first regulator  422  to 0 kPa, or opening the mouth portion plugged by the stopper member  430 . 
     Further, the filling of the containing region  17  with the contents  18  is performed in a state where the filler has been enclosed in the filling portion  60  by the injecting of the filler. 
     More specifically, after enclosing the filler in the filling portion  60  (filling the filler into the filling portion  60  and sealing the filling portion  60 ) as described above, for example, the contents  18  is filled into the containing region  17  through the outlet cylinder portion  15   a  of the spout member  15  as described earlier. 
     The filling with the contents  18  may be carried out before the injecting of filler. 
     The sheet material container  100  may also be formed with an easy-peel region where the inner surface of the container body  20  and the outer surface of the inner bag  40  can be easily peeled. The easy-peel region is a region where the peel strength required to peel off the inner surface of the container body  20  and the outer surface of the inner bag  40  is low. In other words, the peel strength between the inner surface of the container body  20  and the outer surface of the inner bag  40  in the easy-peel region is smaller than the peel strength between the inner surface of the container body  20  and the outer surface of the inner bag  40  in the periphery sealing portion  52  (inner/outer sealing portion  43 ). 
     The inner surface of the container body  20  and the outer surface of the inner bag  40  can thus be maintained in a state of mutual close contact even when a certain time has elapsed after the expanding of the container body  20  and until the injecting of the filler is started. Therefore, when injecting the filler into the filling portion  60 , external air can be prevented from being introduced into the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  via the external air intake holes  96  and  97 , whereby the reproducibility of the volume (full volume) of the containing region  17  becomes more favorable. In addition, the wrinkles formed in the inner bag  40  after filling with the contents are reduced, thus resulting in a more favorable appearance. 
     Here, the easy-peel region is formed by mutually attaching the inner surface of the container body  20  and the outer surface of the inner bag  40  in a state that enables easy peeling. The easy-peel region can be formed, for example, through attachment using an adhesive with low adhesive strength or through partial attaching. The easy-peel region may be achieved by heat-sealing at low temperatures or may be achieved by reducing the seal strength (attachment strength) using a corona treatment and then heat-sealing. Alternatively, an easy-peel region may also be formed on the inner surface of the container body  20  or the outer surface of the inner bag  40  by using a sheet member with easy-peel properties. 
     The easy-peel region may also be formed by causing the inner surface of the container body  20  to come into close contact with the outer surface of the inner bag  40  under an electrostatic force. By imparting a positive charge or a negative charge to the container body  20  and/or the inner bag  40 , the inner surface of the container body  20  and the outer surface of the inner bag  40  can be brought into close contact under an electrostatic force. Methods of imparting a positive charge or a negative charge to the container body  20  and/or the inner bag  40  are not specifically limited; however, a method that is performed using an electrostatic gun, a method that is performed using charging by friction, or a method of reducing the antistatic agent contained in the film, is used. 
     The easy-peel region may also be formed through pseudo-attaching of the inner surface of the container body  20  to the outer surface of the inner bag  40 . 
     One example of pseudo-attaching is a configuration in which the outermost (inner film layer  23  side) layer of the inner-bag forming sheet member  41  is linear low-density polyethylene, and the innermost (inner-bag forming sheet member  41  side) layer of the inner film layer  23  is polyethylene terephthalate (PET). Then, by crimping the main-body forming sheet member  21  and the inner-bag forming sheet member  41 , the surface of the inner film layer  23  on the inner-bag forming sheet member  41  side (for example, composed of PET) and the surface of the inner-bag forming sheet member  41  on the inner film layer  23  side (for example, composed of linear low density polyethylene) can be pseudo-attached. 
     In the case of this configuration, the outer film layer  22  is formed one size larger than the inner film layer  23 , and, in the main-body forming sheet member  21 , the peripheral edge portion of the outer film layer  22  protrudes from the outer periphery of the inner film layer  23 . When the main-body forming sheet member  21  and the inner-bag forming sheet member  41  are mutually heat-sealed to form the container forming sheet member  51 , for example, the entire surface of the main-body forming sheet member  21  and the entire surface of the inner-bag forming sheet member  41  are pressed (full-face pressing) using a press die to crimp the inner film layer  23  to the inner-bag forming sheet member  41 , thereby forming an easy-peel region, and the peripheral edge portion of the outer film layer  22  and the peripheral edge portion of the inner-bag forming sheet member  41  are mutually attached to form the periphery sealing portion  19 . To improve the adhesive strength of the pseudo-attaching, the press die is preferably heated during crimping. 
     Even in a state where the easy-peel region is formed by the inner surface of the container body  20  and the outer surface of the inner bag  40 , the inner surface of the container body  20  and the outer surface of the inner bag  40  preferably come to be mutually detached when a force is applied to the inner bag  40  in a direction that causes the outer surface of the inner bag  40  to separate from the inner surface of the container body  20  due to a reduction in the amount of the contents  18  remaining in the containing region  17 . 
     Second Embodiment 
     Next, a second embodiment will be described using  FIGS.  14 A and  14 B . 
     The method for manufacturing a sheet material container according to this embodiment differs from the method for manufacturing a sheet material container according to the foregoing first embodiment in terms of the points described hereinbelow, and is otherwise configured in the same manner as the method for manufacturing a sheet material container according to the foregoing first embodiment. 
     In the case of this embodiment, the closing of the external air intake hole  96  ( FIG.  14 A ) is performed after the expanding of the container body  20  ( FIG.  12   ), and the injecting of the filler ( FIG.  14 B ) is performed in a state where the external air intake hole  96  is closed. 
     Thus, when injecting the filler into the filling portion  60 , external air can be prevented from being introduced into the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  via the external air intake holes  96  and  97 , whereby the reproducibility of the volume (full volume) of the containing region  17  becomes more favorable. In addition, the wrinkles formed in the inner bag  40  after filling with the contents are reduced, thus resulting in a more favorable appearance. 
     The closing of the external air intake hole  96  ( FIG.  14 A ) can be performed, for example, by closing the external air intake hole  96  using an adhesive tape  460 . Closure of the external air intake hole  96  using the adhesive tape  460  means that the adhesive tape  460  is stuck to the circumferential portion around the external air intake hole  96  on the outer surface of the container body  20  so as to bring the same into contact with this portion in an airtight manner, thereby restricting the intake of external air into the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  via the external air intake hole  96 . 
     After the filler is injected into the filling portion  60  and the filling portion  60  is sealed, the adhesive tape  460  is peeled off from the sheet material container  100 , and the external air intake hole  96  is opened. 
     Third Embodiment 
     Next, a third embodiment will be described using  FIGS.  15 A and  15 B . 
     The method for manufacturing a sheet material container according to this embodiment differs from the method for manufacturing a sheet material container according to the foregoing first embodiment in terms of the points described hereinbelow, and is otherwise configured in the same manner as the method for manufacturing a sheet material container according to the foregoing first embodiment. 
     In the case of this embodiment, after the expanding of the container body  20  ( FIG.  12   ), vacuuming ( FIG.  15 A ) of the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  through the external air intake hole  96 , and injecting of the filler ( FIG.  15 B ) are performed. 
     Thus, when injecting the filler into the filling portion  60 , external air can be prevented from being introduced into the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  via the external air intake holes  96  and  97 , whereby the reproducibility of the volume (full volume) of the containing region  17  becomes more favorable. In addition, the wrinkles formed in the inner bag  40  after filling with the contents are reduced, thus resulting in a more favorable appearance. 
     The vacuuming of the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  through the external air intake hole  96  ( FIG.  15 A ) can be performed, for example, by vacuuming gas from the external air intake hole  96  through the suction piping  471  using a suction pump  472 . A stopper member  470  for closing the external air intake hole  96  is provided at one end of the suction piping  471 , a suction pump  472  is provided at the other end of the suction piping  471 , and a valve  473 , for example, is provided in the middle of the suction piping  471 . 
     Here, closing the external air intake hole  96  with the stopper member  470  means bringing the stopper member  470  into close contact, in an airtight manner, with the circumferential portion around the external air intake hole  96  in the outer surface of the container body  20 , and maintaining, in a state of mutual connection, the suction piping  471  and the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  through the stopper member  470 , and the external air intake holes  96 , and  97 . 
     The vacuuming of the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  through the external air intake hole  96  can be performed by blocking the external air intake hole  96  using the stopper member  470  and opening the valve  473  in a state where the suction pump  472  is in operation, or by operating the suction pump  472  in a state where the valve  473  is open. 
     It is preferable to continue the vacuuming of the gap between the outer surface of the inner bag  40  and the inner surface of the container body  20  through the external air intake hole  96  even when performing the injecting of the filler ( FIG.  15 B ). 
     For example, after the filler is injected into the filling portion  60  and the filling portion  60  is sealed, the suction pump  472  is stopped and the stopper member  470  is removed from the external air intake hole  96 . 
     The present invention is not limited to or by the foregoing embodiments, rather, various modifications and improvements, and so forth, within the scope of achieving the object of the present invention are incorporated herein. 
     For example, although an example of manufacturing a sheet material container  100  that includes an inner bag  40  was described in each of the foregoing embodiments, the present invention is not limited to or by this example, rather, a sheet material container  100  which does not include the inner bag  40  may also be manufactured. When the sheet material container  100  does not include the inner bag  40 , the containing region  17  is configured from the container body  20 . In other words, the container body  20  is formed and the containing region  17  is configured by attaching portions of the inner film layer  23  of the main-body forming sheet member  21  at the periphery sealing portion  19 , and the main-body forming sheet member  21  does not have the external air intake holes  96 ,  97 . 
     Even in a sheet material container  100  that does not include the inner bag  40 , the expanding of the container body  20  is provided as the foregoing embodiment, and the filler is injected in a state where the container body  20  is expanded, thereby enabling filler to be easily injected. 
     In addition, in each of the foregoing embodiments, an example was described in which the expanding of the container body  20  is performed by directly blowing gas into the containing region  17 ; however, the present invention is not limited to or by this example. The container body  20  may also be expanded by introducing gas into the containing region  17  by inserting a parison into the containing region  17  and expanding the parison, or the container body  20  may be expanded by introducing gas into the containing region  17  indirectly by deforming and enlarging the sheet material container  100  by using a machine or an expansion material, or the like. 
     The cap portion  70  may also, for example, not include the pump portion  72 , support cylinder portion  74 , head portion  73 , and nozzle portion  75 , and may be a screw cap with a lid that opens and closes. 
     Furthermore, the sheet material container  100  may stand on its own with the discharge port facing downward (inverted posture), or may be placed with the body portion  11  lying on a mounting surface. 
     Moreover, the various components of the sheet material container  100  do not have to be independent of each other, and a plurality of components may be formed as one component, one component may be formed by a plurality of components, a certain component may be part of another component, and part of a certain component may overlap with part of another component, and so forth. 
     REFERENCE SIGNS LIST 
     
         
           11  Body portion 
           13  Bottom gusset portion (planar portion) 
           14  Top gusset portion (planar portion) 
           15  Spout member 
           17  Containing region 
           18  Contents 
           19  Periphery sealing portion 
           20  Container body 
           20   a  First main surface portion (planar portion, first planar portion) 
           20   b  Second main surface portion (planar portion, second planar portion) 
           21  Main-body forming sheet member 
           22  Outer film layer 
           23  Inner film layer 
           24  Non-attached region 
           25  Extending portion 
           25   a  Injection port 
           26  Main-body sealing portion 
           40  Inner bag 
           41  Inner-bag forming sheet member 
           46  Lateral edge sealing strip 
           51  Container forming sheet member 
           60  Filling portion 
           65  Interfacial connecting portion 
           81 ,  82 ,  83 ,  84 ,  85 ,  86  Folding line 
           96  External air intake hole 
           100  Sheet material container 
           422  First regulator (regulator) 
           430  Stopper member 
           467  Gas supply port