Patent Publication Number: US-2023159233-A1

Title: Package

Description:
TECHNICAL FIELD 
     This invention relates to a package. 
     BACKGROUND ART 
     For example, Japanese Patent Laying-Open No. 2006-256651 (PTL 1) discloses a packaging container including a first package and a second package in which a merchandise can be accommodated, a male portion provided in any one of the first package and the second package, and a female portion provided in any the other of the first package and the second package and coupled to the male portion in sealing. The first package or the second package is provided with a weak portion for separating, at the time of opening, the male portion or the female portion from the package while coupling between the male portion and the female portion is held. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: Japanese Patent Laying-Open No. 2006-256651 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In order to readily confirm the fact of malicious opening of the packaging container, the packaging container disclosed in PTL 1 described above is constructed such that the weak portion is broken at the time of opening of the packaging container while coupling between the male portion and the female portion is held. According to such a construction, however, force produced when the weak portion is broken at the time of opening of the packaging container may greatly deform the packaging container. In this case, excessive force is applied to the merchandise accommodated in the packaging container or the merchandise falls from the packaging container. The merchandise thus cannot properly be protected. 
     Then, an object of this invention is to solve the problem above, and to provide a package that allows subsequent confirmation of the fact of opening while it properly protects an article accommodated therein. 
     Solution to Problem 
     A package according to this invention is a package formed from a flexible sheet material. The package includes a first side and a second side and a hinge that foldably connects the first side and the second side to each other. The first side and the second side make transition between a closed state and an opened state by pivoting around the hinge. In the closed state, a space for accommodating an article is provided. In the opened state, the space is opened. The first side includes a first fitting portion in any one of a projecting shape and a recessed shape, a rigid portion provided in a partial section on a line that goes around the first fitting portion, and a first weak portion provided in a remaining section on the line that goes around the first fitting portion and being lower in rigidity than the rigid portion. The second side includes a second fitting portion in any the other of the projecting shape and the recessed shape and fitted to the first fitting portion in the closed state and a second weak portion provided on a line that goes around the second fitting portion and being lower in rigidity than the rigid portion. 
     Advantageous Effects of Invention 
     According to this invention, a package that allows subsequent confirmation of the fact of opening while it properly protects an article accommodated therein can be provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view showing a package (unused) in an embodiment of this invention. 
         FIG.  2    is a perspective view showing the package (unused) in a direction shown with an arrow II in  FIG.  1   . 
         FIG.  3    is a perspective view showing the package (closed) in the embodiment of this invention. 
         FIG.  4    is a plan view showing a first side within an area surrounded by a chain double-dotted line IV in  FIG.  1   . 
         FIG.  5    is a cross-sectional view showing the first side in a direction shown with an arrow V-V in  FIG.  4   . 
         FIG.  6    is a plan view showing a second side within an area surrounded by a chain double-dotted line VI in  FIG.  1   . 
         FIG.  7    is a cross-sectional view showing the second side in a direction shown with an arrow VII-VII in  FIG.  6   . 
         FIG.  8    is a plan view showing the first side and the second side within an area surrounded by a chain double-dotted line VIII in  FIG.  3   . 
         FIG.  9    is a cross-sectional view showing the first side and the second side in a direction shown with an arrow IX-IX in  FIG.  8   . 
         FIG.  10    is a cross-sectional view showing the first side and the second side when a package is opened. 
         FIG.  11    is a perspective view showing the package (after it is closed) in the embodiment of this invention. 
         FIG.  12    is a plan view showing the first side and a second fitting portion within an area surrounded by a chain double-dotted line XII in  FIG.  11   . 
         FIG.  13    is a cross-sectional view showing the first side and the second fitting portion in a direction shown with an arrow XIII-XIII in  FIG.  12   . 
         FIG.  14    is a cross-sectional view showing the first side and the second side in a direction shown with an arrow XIV-XIV in  FIG.  3   . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of this invention will be described with reference to the drawings. The same or corresponding members in the drawings referred to below have the same reference characters allotted. 
       FIG.  1    is a perspective view showing a package (unused) in an embodiment of this invention.  FIG.  2    is a perspective view showing the package (unused) in a direction shown with an arrow II in  FIG.  1   .  FIG.  3    is a perspective view showing the package (closed) in the embodiment of this invention. 
     Referring to  FIGS.  1  to  3   , a package  10  in the present embodiment is a container for accommodating a medical product in which a drug has been loaded. More specifically, package  10  is a container for accommodating a double chamber type prefilled syringe. 
     Package  10  is formed from a flexible sheet material. Package  10  is formed from a sheet material made of a resin. 
     Package  10  includes a first side  21 , a second side  51 , and a hinge  15 . Hinge  15  foldably connects first side  21  and second side  51  to each other. By pivoting around hinge  15 , first side  21  and second side  51  make transition between a closed state in which a space for accommodating a syringe is provided (a state shown in  FIG.  3   ) and an opened state (a state shown in  FIGS.  1  and  2   ) in which the space is opened. 
     First side  21  is in a rectangular two-dimensional shape. First side  21  is in such a rectangular two-dimensional shape that a direction shown with an arrow  210  is defined as a short-side direction and a direction shown with an arrow  220  is defined as a longitudinal direction. First side  21  includes a first surface  21   a  and a second surface  21   b . First surface  21   a  is arranged to face an outer space in the closed state. Second surface  21   b  is arranged on a rear side of first surface  21   a.    
     Second side  51  is in a rectangular two-dimensional shape. Second side  51  is in such a rectangular two-dimensional shape that the direction shown with arrow  210  is defined as the short-side direction and the direction shown with arrow  220  is defined as the longitudinal direction. Second side  51  includes a third surface  51   a  and a fourth surface  51   b . Third surface  51   a  is arranged to face the outer space in the closed state. Fourth surface  51   b  is arranged on a rear side of third surface  51   a . Second surface  21   b  and fourth surface  51   b  face each other in the closed state. 
     First side  21  and second side  51  are not limited in shape to the rectangular shape above, and can be in any shape. For the sake of convenience of illustration, the direction (a direction of radius of a pivot center axis of first side  21  and second side  51 ) shown with arrow  210  is herein referred to as a “short-side direction of first side  21  and second side  51 ” and the direction (an axial direction of the pivot center axis of first side  21  and second side  51 ) shown with arrow  220  is referred to as a “longitudinal direction of first side  21  and second side  51 .” 
     Hinge  15  extends in the longitudinal direction of first side  21  and second side  51 . Hinge  15  is provided along a long side in a plan view of first side  21  and second side  51 . Hinge  15  is provided as a perforated portion provided by intermittently cutting the sheet material that forms package  10 . 
     First side  21  is provided with a depression  23 . Depression  23  is in a depressed shape on a side of second surface  21   b . Depression  23  is in a depressed shape in conformity with a shape of a syringe. A syringe is arranged in depression  23 . 
     Second side  51  is provided with a depression  53 . Depression  53  is in a depressed shape on a side of fourth surface  51   b . Together with depression  23 , depression  53  defines a space for accommodating a syringe. 
     In the present embodiment, first side  21  where the syringe is arranged serves as a bottom (a main body) of package  10  and second side  51  that covers the syringe arranged in first side  21  serves as a lid of package  10 . 
     In a general manner of use, as shown in  FIG.  1   , first side  21  and the second side are set to the closed state as first side  21  is set to a posture in which second surface  21   b  faces up and first surface  21   a  faces down and second side  51  is pivoted around hinge  15  in a direction shown with an arrow  110 A. As shown in  FIG.  3   , package  10  is set to the opened state as second side  51  is pivoted around hinge  15  in a direction shown with an arrow  110 B while first side  21  is maintained in the posture in which second surface  21   b  faces up and first surface  21   a  faces down. 
     First side  21  includes a peripheral portion  24 , a flange  25 , a hold  26 , and a wall  28 . 
     Peripheral portion  24  defines a periphery of the sheet material that forms first side  21  at a position distant in the direction of radius from a pivot center of first side  21  and second side  51  of hinge  15 . Peripheral portion  24  extends in the longitudinal direction of first side  21 . Peripheral portion  24  extends along the long side in the plan view of first side  21 . Peripheral portion  24  is opposed to hinge  15  in the short-side direction of first side  21 . 
     Flange  25  extends like a band along peripheral portion  24 . Flange  25  extends in the longitudinal direction of first side  21  over a prescribed width in the short-side direction of first side  21 . Flange  25  is provided between peripheral portion  24  and depression  23  in the short-side direction of first side  21 . 
     Hold  26  is a part of flange  25 . Hold  26  is a part held by a user mainly when package  10  is opened. Hold  26  is provided with a projection  27 . Projection  27  is in a shape projecting on the side of second surface  21   b  and extends in the longitudinal direction of first side  21 . 
     Wall  28  is in a shape of a wall rising from second surface  21   b . Wall  28  is provided in a partial section of a surrounding path that surrounds depression  23 . The surrounding path that surrounds depression  23  is in a rectangular shape. Wall  28  is provided at least at positions including four corners of the rectangular surrounding path. Wall  28  is located within depression  53  in second side  51  in the closed state. 
     Second side  51  includes a peripheral portion  54  and a flange  55 . Peripheral portion  54  defines a periphery of the sheet material that forms second side  51  at a position distant in the direction of radius from the pivot center of first side  21  and second side  51  in hinge  15 . Peripheral portion  54  extends in the longitudinal direction of second side  51 . Peripheral portion  54  extends along a long side in a plan view of second side  51 . Peripheral portion  54  is opposed to hinge  15  in the short-side direction of second side  51 . 
     Flange  55  extends like a band along peripheral portion  54 . Flange  55  extends in the longitudinal direction of second side  51  over a prescribed width in the short-side direction of second side  51 , except for a position where a notch  56  which will be described later is provided. Flange  55  is provided between peripheral portion  54  and depression  53  in the short-side direction of second side  51 . Flange  55  is superimposed on flange  25  of first side  21  in the closed state. 
     Flange  55  is provided with notch  56 . Notch  56  is in a notched shape that opens on a side of peripheral portion  54 . Notch  56  is provided to expose hold  26  in first side  21  through flange  55  in the closed state. 
       FIG.  4    is a plan view showing the first side within an area surrounded by a chain double-dotted line IV in  FIG.  1   .  FIG.  5    is a cross-sectional view showing the first side in a direction shown with an arrow V-V in  FIG.  4   . 
     Referring to  FIGS.  1  to  5   , first side  21  further includes a first fitting portion  31 . First fitting portion  31  is in a projecting shape when viewed from second side  51  in the closed state. 
     First fitting portion  31  is in the projecting shape that projects from second surface  21   b  when viewed from second side  51  in the closed state and in the recessed shape recessed from first surface  21   a  when viewed from the opposite side. First fitting portion  31  is provided in flange  25 . First fitting portion  31  is provided at a position adjacent to peripheral portion  24 . First fitting portion  31  is provided between peripheral portion  24  and depression  23  in the short-side direction of first side  21 . First fitting portion  31  is provided in a central portion in the longitudinal direction of first side  21 . 
     First fitting portion  31  is defined by two straight lines that extend in the longitudinal direction of first side  21 , a semicircle that connects one ends of the straight lines to each other, and a semicircle that connects the other ends of the straight lines to each other, and is in a two-dimensional shape like a track with a central axis  101  being defined as the center. 
     First side  21  further includes a rigid portion  46  and a first weak portion  41 . Rigid portion  46  and first weak portion  41  are provided on a line that goes around first fitting portion  31 . Rigid portion  46  is provided in a partial section on the line that goes around first fitting portion  31 . First weak portion  41  is provided in a remaining section on the line that goes around first fitting portion  31 . First weak portion  41  is lower in rigidity than rigid portion  46 . 
     First weak portion  41  is provided as a cut portion  42  provided by continuously cutting first side  21  along the line that goes around first fitting portion  31 . Cut portion  42  extends between one end  42 P and the other end  42 Q. One end  42 P and the other end  42 Q are located between central axis  101  and peripheral portion  24  in the short-side direction of first side  21 . 
     Cut portion  42  includes an inner portion  43  and a pair of outer portions  44  ( 44   p  and  44   q ). Inner portion  43  is provided at a position where a length from peripheral portion  24  to inner portion  43  in the short-side direction of first side  21  is equal to or longer than a length from peripheral portion  24  to central axis  101  in the short-side direction of first side  21 . Inner portion  43  extends along a perimeter of first fitting portion  31  at a certain distance from first fitting portion  31  in the two-dimensional shape like the track. 
     The pair of outer portions  44  is provided at positions where a length from peripheral portion  24  to outer portion  44  in the short-side direction of first side  21  is shorter than the length from peripheral portion  24  to central axis  101  in the short-side direction of first side  21 . Outer portion  44   p  extends in the short-side direction of first side  21  from one end of inner portion  43  toward one end  42 P of cut portion  42 . Outer portion  44   q  extends in the short-side direction of first side  21  from the other end of inner portion  43  toward the other end  42 Q of cut portion  42 . 
     Rigid portion  46  extends along a virtual straight line that connects one end  42 P of cut portion  42  and the other end  42 Q of cut portion  42  to each other. First side  21  is not cut on the virtual straight line that connects one end  42 P of cut portion  42  and the other end  42 Q of cut portion  42  to each other and rigid portion  46  is formed from a non-cut portion of first side  21 . 
     In such a construction, rigidity of first weak portion  41  formed from cut portion  42  is zero and lower than rigidity of rigid portion  46 . 
       FIG.  6    is a plan view showing the second side within an area surrounded by a chain double-dotted line VI in  FIG.  1   .  FIG.  7    is a cross-sectional view showing the second side in a direction shown with an arrow VII-VII in  FIG.  6   . 
     Referring to  FIGS.  1  to  3 ,  6 , and  7   , second side  51  further includes a second fitting portion  61 . Second fitting portion  61  is in a recessed shape when viewed from first side  21  in the closed state. 
     Second fitting portion  61  is in the recessed shape recessed from fourth surface  51   b  when viewed from first side  21  in the closed state and in the projecting shape projecting from third surface  51   a  when viewed from the opposite side. Second fitting portion  61  is provided in flange  55 . Second fitting portion  61  is provided at a position adjacent to peripheral portion  54 . Second fitting portion  61  is provided between peripheral portion  54  and depression  53  in the short-side direction of second side  51 . Second fitting portion  61  is provided in the central portion in the longitudinal direction of second side  51 . 
     Second fitting portion  61  is defined by two straight lines that extend in the longitudinal direction of second side  51 , a semicircle that connects one ends of the straight lines to each other, and a semicircle that connects the other ends of the straight lines to each other, and is in a two-dimensional shape like a track with a central axis  102  being defined as the center. 
     Second side  51  further includes a second weak portion  71 . Second weak portion  71  is provided along a line that goes around second fitting portion  61 . Second weak portion  71  extends along a perimeter of second fitting portion  61  at a certain distance from second fitting portion  61  in the two-dimensional shape like the track. 
     Second weak portion  71  is provided as a perforated portion  72  provided by intermittently cutting second side  51  along the line that goes around second fitting portion  61 . 
     Perforated portion  72  includes a cut portion  73  and non-cut portions  76 ,  77 , and  78 . Cut portion  73  is a part where second side  51  is cut in perforated portion  72 . Non-cut portions  76 ,  77 , and  78  are parts where second side  51  is not cut in perforated portion  72 . Cut portion  73  and non-cut portions  76 ,  77 , and  78  are alternately aligned on the line that goes around second fitting portion  61  to thereby provide perforated portion  72 . 
     Cut portion  73  is longer in total length than non-cut portions  76 ,  77 , and  78 . Non-cut portion  76  and non-cut portion  78  are located on respective opposing sides of second fitting portion  61  in the longitudinal direction of second side  51 . Non-cut portion  77  is located between second fitting portion  61  and depression  53  in the short-side direction of second side  51 . Non-cut portion  77  is located in the central portion between non-cut portion  76  and non-cut portion  78  in the longitudinal direction of second side  51 . 
     In such a construction, second weak portion  71  formed from perforated portion  72  is lower in rigidity than rigid portion  46 . Second weak portion  71  formed from perforated portion  72  is higher in rigidity than first weak portion  41  formed from cut portion  42 . 
       FIG.  8    is a plan view showing the first side and the second side within an area surrounded by a chain double-dotted line VIII in  FIG.  3   .  FIG.  9    is a cross-sectional view showing the first side and the second side in a direction shown with an arrow IX-IX in  FIG.  8   . 
     Referring to  FIGS.  3 ,  8 , and  9   , in the closed state, first fitting portion  31  and second fitting portion  61  are fitted to each other. 
     More specifically, first fitting portion  31  in the projecting shape that projects from second surface  21   b  is fitted to an inner side of second fitting portion  61  in the recessed shape recessed from fourth surface  51   b . As first fitting portion  31  and second fitting portion  61  are fitted to each other, package  10  is closed. Owing to a fitting structure of first fitting portion  31  and second fitting portion  61 , the closed state of package  10  can be obtained without using an adhesive. While first fitting portion  31  and second fitting portion  61  are fitted to each other, central axis  101  of first fitting portion  31  and central axis  102  of second fitting portion  61  are coaxially arranged. 
     As shown in  FIG.  8   , in the closed state, non-cut portions  76 ,  77 , and  78  in perforated portion  72  are arranged as being superimposed on an area from first fitting portion  31  to first weak portion  41  (cut portion  42 ) on the surface of first side  21 . Non-cut portions  76 ,  77 , and  78  in perforated portion  72  are arranged on a line of first weak portion  41  (cut portion  42 ) or on an inner side of first weak portion  41  (cut portion  42 ) when viewed from central axes  101  and  102 . 
       FIG.  10    is a cross-sectional view showing the first side and the second side when the package is opened.  FIG.  10    shows a cross-section of first side  21  and second side  51  within an area shown in  FIG.  9   . 
     Referring to  FIGS.  3 ,  9 , and  10   , when package  10  is opened, external force is applied to first fitting portion  31  and second fitting portion  61  fitted to each other. 
     More specifically, force (force in a direction shown with an arrow  230  in  FIGS.  3  and  9   ) in a direction from second side  51  toward first side  21  is applied from the side of second side  51  to second fitting portion  61  and first fitting portion  31  arranged on the inner side of second fitting portion  61 . Second weak portion  71  of second side  51  is thus broken to separate second fitting portion  61  from second side  51 . 
     At this time, as shown in  FIG.  10   , first side  21  is deformed as moving away from first side  21  at first weak portion  41  while first fitting portion  31  remains connected to first side  21  at rigid portion  46 . As shown with an arrow  240  in  FIG.  10   , first side  21  is deformed in such a manner that first fitting portion  31  pivotally moves around rigid portion  46 . With this deformation of first side  21 , large shear force is applied to non-cut portions  76 ,  77 , and  78  in perforated portion  72  in second weak portion  71 . Therefore, second weak portion  71  can readily be broken. Package  10  can thus be prevented from greatly deforming with break of second weak portion  71  at the time of opening of package  10 . Consequently, the syringe accommodated in package  10  can properly be protected. 
     In particular, when an article accommodated in the package is a medical product in which a drug (an anticancer drug or the like) has been loaded, the accommodated article is required to safely be handled. In the present embodiment, package  10  does not greatly deform. Therefore, drop of the syringe which is the accommodated article or leakage of a drug from the syringe during opening works can be prevented. 
     In general, package  10  is opened in such a posture (a posture shown in  FIG.  3   ) that second side  51  which is the lid is overlaid from above over first side  21  provided with depression  23  where the syringe is arranged. In this case, first fitting portion  31  is in the projecting shape when viewed from second side  51  in the closed state and second fitting portion  61  is in the recessed shape when viewed from first side  21  in the closed state. Therefore, in the posture of package  10  at the time of opening, first fitting portion  31  and second fitting portion  61  are in a form projecting upward. Thus, in opening package  10 , works for applying external force to first fitting portion  31  and second fitting portion  61  are readily performed. 
     For applying external force to first fitting portion  31  and second fitting portion  61 , a manner of use to press first fitting portion  31  and second fitting portion  61  from the outside of peripheral portions  24  and  54  with a finger (thumb) is assumed. In the present embodiment, in first side  21 , the length from peripheral portion  24  to first weak portion  41  (cut portion  42 ) is longer than the length from peripheral portion  24  to rigid portion  46 . According to such a construction, first weak portion  41  (cut portion  42 ) separated from first side  21  is located in a region on an inner side in first side  21  far from peripheral portion  24 , and rigid portion  46  that remains connected to first side  21  is located in a region on an outer side in first side  21  close to peripheral portion  24 . Therefore, first fitting portion  31  and second fitting portion  61  are readily pressed with a finger (thumb). 
     In the closed state shown in  FIG.  8   , non-cut portions  76 ,  77 , and  78  in perforated portion  72  are arranged as being superimposed on the area from first fitting portion  31  to first weak portion  41  (cut portion  42 ) on the surface of first side  21 . In this case, first side  21  is deformed in such a manner that first fitting portion  31  separates from first side  21  at first weak portion  41  (cut portion  42 ). Therefore, non-cut portions  76 ,  77 , and  78  in perforated portion  72  can readily be broken. 
     First weak portion  41  is formed from cut portion  42  provided by continuously cutting first side  21  along the line that goes around first fitting portion  31 . Thus, when package  10  is opened, first side  21  can be deformed with weaker force to separate first fitting portion  31  from first side  21  at first weak portion  41 . 
     Second weak portion  71  is formed from perforated portion  72  provided by intermittently cutting second side  51  along the line that goes around second fitting portion  61 . Thus, while package  10  is unused, such a form that second fitting portion  61  is integrated with second side  51  is realized, whereas at the time of opening of package  10 , second weak portion  71  can be broken by applying external force to first fitting portion  31  and second fitting portion  61 . 
     First weak portion  41  and second weak portion  71  are not limited to the form of the cut portion or the perforated portion, and may be formed, for example, from a small thickness portion smaller in thickness than other portions. 
       FIG.  11    is a perspective view showing the package (after it is closed) in the embodiment of this invention.  FIG.  12    is a plan view showing the first side and the second fitting portion within an area surrounded by a chain double-dotted line XII in  FIG.  11   .  FIG.  13    is a cross-sectional view showing the first side and the second fitting portion in a direction shown with an arrow XIII-XIII in  FIG.  12   . 
     Referring to  FIGS.  3  and  11  to  13   , second side  51  is pulled up from first side  21  while holding hold  26  of first side  21 . Second side  51  is thus pivoted around hinge  15  in the direction shown with arrow  110 B and package  10  is set to the opened state. 
     Since second weak portion  71  has been broken in the works for applying external force to first fitting portion  31  and second fitting portion  61  described previously, second fitting portion  61  remains at first side  21  as being fitted to first fitting portion  31 . Second side  51  is provided with an opening  81  resulting from separation of second fitting portion  61 . Since the fact of opening of package  10  can thus subsequently be confirmed, contamination or replacement of a drug in the syringe can be noticed. 
     When second side  51  is pulled up from first side  21  in opening package  10  without performing works for applying external force to first fitting portion  31  and second fitting portion  61  as well, force of fitting between first fitting portion  31  and second fitting portion  61  overcomes rigidity of second weak portion  71  so that second fitting portion  61  is separated from second side  51 . Therefore, regardless of an opening method, the fact of opening of package  10  can subsequently be confirmed. 
       FIG.  14    is a cross-sectional view showing the first side and the second side in a direction shown with an arrow XIV-XIV in  FIG.  3   . 
     Referring to  FIGS.  1 ,  3 , and  14   , first side  21  further includes a third fitting portion  91 . Third fitting portion  91  is provided at a position distant from first fitting portion  31 . Third fitting portion  91  is provided at each of four corners of wall  28 . Third fitting portion  91  is in a projecting shape projecting from wall  28 . 
     Second side  51  further includes a fourth fitting portion  92 . Fourth fitting portion  92  is provided at a position distant from second fitting portion  61 . Fourth fitting portion  92  is provided at each of four locations (positions surrounded by chain double-dotted lines A, B, C, and D in  FIG.  1   ) corresponding to positions where third fitting portions  91  are provided. Fourth fitting portion  92  is provided in an inner wall of depression  53 . Fourth fitting portion  92  is in the recessed shape recessed from the inner wall of depression  53 . 
     Third fitting portion  91  and fourth fitting portion  92  are fitted to each other in the closed state. According to such a construction, first side  21  and second side  51  can more reliably be held in the closed state. 
     Features and functions and effects of the present invention are summarized below. 
     A package according to this invention is a package formed from a flexible sheet material. The package includes a first side and a second side and a hinge that foldably connects the first side and the second side to each other. The first side and the second side make transition between a closed state and an opened state by pivoting around the hinge. In the closed state, a space for accommodating an article is provided. In the opened state, the space is opened. The first side includes a first fitting portion in any one of a projecting shape and a recessed shape, a rigid portion provided in a partial section on a line that goes around the first fitting portion, and a first weak portion provided in a remaining section on the line that goes around the first fitting portion and being lower in rigidity than the rigid portion. The second side includes a second fitting portion in any the other of the projecting shape and the recessed shape and fitted to the first fitting portion in the closed state and a second weak portion provided on a line that goes around the second fitting portion and being lower in rigidity than the rigid portion. 
     According to the package thus constructed, in opening the package, by applying external force to the first fitting portion and the second fitting portion fitted to each other, the second weak portion is broken to separate the second fitting portion from the second side. At this time, the first side is deformed such that the first fitting portion is separated from the first side at the first weak portion while it remains connected to the first side at the rigid portion. Therefore, the package can be prevented from greatly deforming with break of the second weak portion. Consequently, a package that allows subsequent confirmation of the fact of opening while it properly protects an accommodated article can be realized. 
     Preferably, the first side further includes a peripheral portion that defines a periphery of the sheet material at a position distant in a direction of radius from a pivot center of the first side and the second side in the hinge. The first fitting portion is provided at a position adjacent to the peripheral portion. A length from the peripheral portion to the first weak portion is longer than a length from the peripheral portion to the rigid portion. 
     According to the package thus constructed, when a manner of use to press the first fitting portion and the second fitting portion with a finger from the outside of the peripheral portion in opening the package is assumed, the first weak portion for separating the first fitting portion from the first side is located at a position more distant from the peripheral portion, and hence the first fitting portion and the second fitting portion are readily pressed with the finger. 
     Preferably, the first weak portion is provided by continuously cutting the first side along the line that goes around the first fitting portion. 
     According to the package thus constructed, in opening the package, the first side can be deformed with weaker force to separate the first fitting portion from the first side at the first weak portion. 
     Preferably, the second weak portion is provided as a perforated portion provided by intermittently cutting the second side along the line that goes around the second fitting portion. 
     According to the package thus constructed, while the package is unused, such a form that the second fitting portion is integrated with the second side is realized, whereas at the time of opening of the package, the second weak portion can be broken by applying external force to the first fitting portion and the second fitting portion. 
     Preferably, the perforated portion includes a cut portion where the second side is cut and a non-cut portion where the second side is not cut. In the closed state, the non-cut portion is arranged as being superimposed on an area from the first fitting portion to the first weak portion on a surface of the first side. 
     According to the package thus constructed, in opening the package, the first side is deformed to separate the first fitting portion from the first side at the first weak portion. Therefore, as the non-cut portions in the perforated portion are arranged as being superimposed on the area from the first fitting portion to the first weak portion on the surface of the first fitting portion, the non-cut portions can readily be broken. 
     Preferably, the first side is provided with a depression in a depressed shape in conformity with a shape of the article. The first fitting portion is in the projecting shape when viewed from the second side in the closed state. The second fitting portion is in the recessed shape when viewed from the first side in the closed state. 
     According to the package thus constructed, the package is opened in such a posture that the second side is overlaid from above over the first side where an article is arranged in the depression. In this case, the first fitting portion and the second fitting portion are provided to project upward. Therefore, in opening the package, works for applying external force to the first fitting portion and the second fitting portion are readily performed. 
     Preferably, the first side further includes a third fitting portion provided at a position distant from the first fitting portion. The second side further includes a fourth fitting portion provided at a position distant from the second fitting portion and fitted to the third fitting portion in the closed state. 
     According to the package thus constructed, by providing a fitting structure of the third fitting portion and the fourth fitting portion separately from the fitting structure of the first fitting portion and the second fitting portion, the first side and the second side can more reliably be held in the closed state. 
     It should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims rather than the description above and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. 
     INDUSTRIAL APPLICABILITY 
     This invention is applied to a package for accommodating an article. 
     REFERENCE SIGNS LIST 
       10  package;  15  hinge;  21  first side;  21   a  first surface;  21   b  second surface;  23 ,  53  depression;  24 ,  54  peripheral portion;  25 ,  55  flange;  26  hold;  27  projection;  28  wall;  31  first fitting portion;  41  first weak portion;  42 ,  73  cut portion;  42 P one end;  42 Q the other end;  43  inner portion;  44 ,  44   p ,  44   q  outer portion;  46  rigid portion;  51  second side;  51   a  third surface;  51   b  fourth surface;  56  notch;  61  second fitting portion;  71  second weak portion;  72  perforated portion;  76 ,  77 ,  78  non-cut portion;  81  opening;  91  third fitting portion;  92  fourth fitting portion;  101 ,  102  central axis