Packaging box

Abstract

To provide a packaging box which can be sealed without using a tape, can hold a lid in a strong lock state, after sealing, and can prevent fraudulent opening by mischief.SOLUTION: A packaging box 1 has a quadrangle bottom plate 2, a pair of first side plates 3 which are continuously provided on a pair of facing end edges of the bottom plate, a pair of second side plates 4 and 5 which are continuously provided on the other pair of facing end edges of the bottom plate, a pair of first flaps which are continuously provided on the pair of first side plates, a second flap 7 which is continuously provided on the second side plate, a third flap 8 which is continuously provided on the second side plate, a pair of fourth flaps 9 which are continuously provided on the pair of facing end edges, an insertion part 10 which is continuously provided on the end edge of the third flap, and a lock piece 20 formed on the second flap, wherein the lock piece is constituted by being surrounded by a lock piece crease line 21, and a lock piece breakable line having a breakable connection part in at least one place, and a lock piece fitting port is provided on the insertion part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a packaging box that can be sealed without using sealing tape and has a locking structure that can prevent unauthorized opening by tampering or the like after sealing. [Background technology]

[0002] With the recent spread of mail order sales such as online shopping, the delivery of goods by post and courier services is becoming more common, and there is a growing demand for low-profile packaging boxes that can be dropped into mailboxes.

[0003] Conventional packaging boxes are made of sheet-like materials such as corrugated cardboard or paperboard, and are generally sealed using tape or a shipping slip. To avoid the need for tape, boxes typically have a structure that provides an insert with a return or a double-insertion locking structure.

[0004] For example, a packaging box has been proposed that has a locking structure that secures the top panel by fitting a locking piece of a movable flap formed on the front panel side into a locking hole formed in an insertion flap on the top panel side that serves as the lid (see Patent Document 1).

[0005] In the packaging box described in Patent Document 1, the locking structure has a locking hole drilled at a predetermined position in a wide, tongue-shaped insertion flap that is bent and extended from the top panel. Furthermore, in this locking structure, a portion of the front panel is cut out and raised into a long tongue-shaped movable flap, and the free end of the movable flap is sharpened to form a locking piece. In this locking structure, the locking piece at the tip of the movable flap on the front panel is inserted into the locking hole on the top panel in the closed state, locking the top panel in the closed state. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-278251 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the above-mentioned conventional locking structure that provides a barbed insertion portion and the locking structure described in Patent Document 1 have the problem that the sealing operation is cumbersome. In addition, in the case of Patent Document 1, because a movable flap connected to the locking piece is provided, the locking piece can be pulled out after sealing, which creates the problem that it is not possible to prevent unauthorized opening by tampering or the like.

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a packaging box that can be sealed without using tape, and that can keep the lid in a firmly locked state after sealing, thereby preventing it from being opened illegally by tampering or the like. [Means for solving the problem]

[0009] The packaging box of the present invention comprises a rectangular bottom plate, a pair of first side plates connected to a pair of opposing edges of the bottom plate via first fold lines, a pair of second side plates connected to a pair of opposing edges of the bottom plate in a direction intersecting the opposing direction of the first side plates via second fold lines, and a pair of first flaps connected to upper edges of the pair of first side plates via first flap fold lines, A rectangular parallelepiped packaging box having a second flap connected to an upper edge of one of the pair of second side panels via a second flap fold line, and a third flap connected to an upper edge of the other of the pair of second side panels via a third flap fold line and overlapping the first flap and the second flaps, wherein the second flap is provided with a pair of insertion slits along the second flap fold line, and a lock piece positioned between the pair of insertion slits and having both side ends adjacent to the pair of insertion slits, and the lock piece is provided with a locking piece extending from the second flap fold line to the second side The packaging box is characterized in that it is surrounded by a locking piece fold line formed at a position a predetermined distance away from the plate side, and a locking piece breakable line that connects both ends of the locking piece fold line and extends in a direction away from the locking piece fold line and bulges toward the edge of the second flap, and has a breakable connecting portion at at least one location, and the edge of the third flap is provided with an insertion portion that is connected to the insertion portion fold line and can be inserted into the pair of insertion slits, and a locking piece insertion opening is provided at the base end of the insertion portion so that the locking pieces can be inserted (hereinafter referred to as the ``packaging box of the first invention'').

[0010] The packaging box of the first invention has a locking structure when sealed, in which the second flap (insertion receiving side) is provided with a pair of insertion slits along the second flap fold line, and a locking piece located between the pair of insertion slits with both side ends adjacent to the pair of insertion slits, and the locking piece is surrounded by a locking piece fold line formed at a position a predetermined distance away from the second flap fold line toward the second side panel, and a locking piece breakable line connecting both ends of the locking piece fold line and extending in a direction away from the locking piece fold line and bulging toward the edge of the second flap, and having a breakable connecting portion in at least one location. In addition, an insertion portion is provided that is connected to the edge of the third flap via the insertion portion fold line and can be inserted into a pair of insertion slits, and a lock piece insertion opening into which the lock piece can be inserted is provided at the base end of the insertion portion.When the box is sealed, the insertion portion on the third flap (which functions as the top plate (lid) of the packaging box) is inserted into the pair of insertion slits of the second flap, and the lock piece on the second flap is inserted into the lock piece insertion opening provided at the base end of the insertion portion.

[0011] According to this configuration, when the second flap is folded along the second flap fold line during sealing, the locking piece assumes an inclined position between the second side panel and the second flap. When the insertion portion of the third flap is inserted into the pair of insertion slits of the second flap, the pushing force of the insertion portion pushes the tip of the locking piece downward, breaking the connecting portion. When the insertion portion is further inserted, the tip of the locking piece can easily enter the locking piece insertion opening provided at the base end of the insertion portion, and the upper surface of the tip of the locking piece is engaged by surface contact with the underside of the second flap. This makes it impossible to remove the locking piece after sealing, maintaining the third flap in a securely locked state and preventing tampering or other unauthorized opening.

[0012] Furthermore, in the packaging box of the first invention, the opening of the box body can be tightly closed without taping, and since it does not have a locking operation flap like the locking mechanism of Patent Document 1 mentioned above, the locking piece cannot be removed after the box is sealed, which prevents unauthorized unlocking and opening.

[0013] Therefore, according to the packaging box of the first invention, no tape is required when sealing the box, which reduces the amount of work required and is environmentally friendly. In addition, after sealing the box, the lid can be kept firmly locked, preventing it from being opened illicitly by tampering, etc.

[0014] In the packaging box of the first invention, it is preferable that the insertion portion fold lines are provided on both sides of the lock piece insertion opening, and each is formed so as to extend diagonally from the outer end to the center and away from the edge of the third flap (hereinafter referred to as the "packaging box of the second invention").

[0015] In the packaging box of the second aspect of the present invention, the insertion portion fold lines are provided on both sides of the lock piece insertion opening, and each is formed so as to extend diagonally from the outer end to the center and away from the edge of the third flap. Therefore, when the insertion portion is folded along the insertion portion fold lines during sealing, the insertion portion is folded inward from a direction perpendicular to the third flap, and the connecting portion of the lock piece's lock piece breakable line can be easily broken.

[0016] Therefore, in the packaging box of the second aspect of the present invention, when the insertion part is folded along the insertion part crease line during sealing, the insertion part is folded inward from a direction perpendicular to the third flap, which makes it possible to easily break the connecting part of the locking piece's locking piece breakable line, thereby enabling a smooth locking operation during sealing.

[0017] In the packaging box of the first or second invention, it is preferable that a return portion is provided on both sides of the base end of the insertion portion to prevent the insertion portion from slipping out when inserted into the pair of insertion slits (hereinafter referred to as the "packaging box of the third invention").

[0018] In the packaging box of the third invention, the insertion part has return sections on both sides of the base end of the insertion part to prevent the insertion part from slipping out when inserted into the pair of insertion slits. After the insertion part is inserted into the pair of insertion slits, the return sections are locked with the locking sections on the outer ends of the insertion slits, forming a double lock structure together with the locking pieces, making it difficult for the insertion part to slip out. This allows the third flap to be held in a more secure locked state, reliably preventing unauthorized opening by tampering or the like.

[0019] Therefore, according to the packaging box of the third invention, the double locking structure of the locking piece and the flap makes it difficult for the lock to be released, so that the third flap can be held in a more secure locked state and it can be reliably prevented from being opened illegally by tampering or the like.

[0020] In the packaging box of the first or second invention, it is preferable that the tip of the insertion portion is formed with an insertion guide portion having a convex shape that makes it easy to insert into the pair of insertion slits (hereinafter referred to as the "packaging box of the fourth invention").

[0021] In the packaging box of the fourth aspect of the present invention, an insertion guide portion is formed at the tip of the insertion portion, which makes it easy to insert the tip of the insertion portion into a pair of insertion slits when sealing the box, allowing the sealing operation to be carried out smoothly.

[0022] Therefore, according to the packaging box of the fourth aspect of the present invention, the leading ends of the insertion portions can be easily inserted into the pair of insertion slits when sealing the box, thereby improving workability.

[0023] In the packaging box of the first or second invention, it is preferable that the lock piece breakable line consists of a cut line that is cut in one place in the center and has a connecting portion that can be broken when the insertion portion is inserted into the pair of insertion slits (hereinafter referred to as the "packaging box of the fifth invention").

[0024] In the packaging box of the fifth aspect of the present invention, the locking piece breakable line in the locking piece consists of a cut line that is cut in one place in the center and has a connecting portion that can be broken when the insertion portion is inserted into a pair of insertion slits.Therefore, when the second flap is folded along the second flap fold line during sealing, the locking piece becomes inclined between the second side panel and the second flap, and when the insertion portion on the third flap side is inserted into a pair of insertion slits in the second flap, the connecting portion can be easily broken by the pressing force of the insertion portion.

[0025] Therefore, according to the packaging box of the fifth aspect of the present invention, the locking piece has a cut line with a connecting portion at one location on the locking piece breakable line, so that when the insertion portion is inserted into a pair of insertion slits in the second flap during sealing, the connecting portion is easily broken by the pressing force of the insertion portion.

[0026] In addition, in the packaging box of the first or second invention of the present invention, it is preferable that the third flap is provided with a finger hole for placing fingers when opening, and a breakable line extending from both side edges of the finger hole to both outer ends of the insertion portion fold line (hereinafter referred to as the "packaging box of the sixth invention of the present invention").

[0027] In the packaging box of the sixth aspect of the present invention, the third flap is provided with a finger hole for placing fingers when opening, and a pair of breakable lines extending from both side edges of the finger hole to both ends of the fold line of the insertion portion, so that when opening, the third flap can be opened by grasping the edge of the finger hole with the tips of one's finger and pulling up, thereby breaking the pair of breakable lines extending from both side edges of the finger hole to both ends of the fold line of the insertion portion. This allows the box to be opened easily and quickly while in a locked state.

[0028] Furthermore, in the packaging box of the sixth aspect of the present invention, when the box is opened, a portion of the third flap that is broken along a pair of breakable lines is connected to the locking piece via the insertion portion, so that the insertion portion remains locked even after opening, and there is only one disposal piece, making disposal easy.

[0029] Therefore, according to the packaging box of the sixth aspect of the present invention, it can be opened easily and quickly while locked by the locking piece. Furthermore, because a part of the broken third flap is connected to the locking piece via the insertion part, the insertion part remains locked even after opening, and there is only one disposal piece, making disposal easy. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a perspective view showing an embodiment of a packaging box of the present invention. [Figure 2] FIG. 2 is a development view of the paperboard that makes up the packaging box of FIG. 1. [Figure 3] 1. FIG. 4 is a first perspective view showing the assembly process of the packaging box of FIG. 1, illustrating the state after the left, right and rear side surfaces and flaps of the packaging box have been folded and assembled. [Figure 4] 1. FIG. 4 is a second perspective view showing the assembly process of the packaging box of FIG. 1, illustrating the state after the front side surface and flaps of the packaging box are folded and assembled. [Figure 5] 1, and is a perspective view illustrating a state during assembly when the third flap and the insertion portion of the packaging box are folded and inserted into the insertion opening. FIG. [Figure 6] 1, and is an enlarged perspective view of a main part illustrating a state when an insertion portion of the packaging box is inserted into an insertion opening. FIG. [Figure 7] 1, and is an enlarged perspective view of a main part illustrating a state during assembly after the insertion portion of the packaging box has been inserted into the insertion opening. FIG. [Figure 8] 1. FIG. 4 is a cross-sectional view showing the assembly process of the packaging box of FIG. 1, illustrating the state before and after inserting the insertion portion of the packaging box into the insertion opening. [Figure 9] FIG. 2 is a perspective view illustrating an operation for opening the packaging box of FIG. 1. [Figure 10] 2 is a perspective view illustrating the state when the packaging box of FIG. 1 is disposed of after being opened. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, a packaging box 1 according to one embodiment of the present invention (hereinafter simply referred to as "this embodiment") will be described with reference to FIGS.

[0032] 1 and 2, the packaging box 1 of this embodiment is a low, approximately rectangular box made of a single blank, and can be mailed. That is, the packaging box 1 comprises a rectangular bottom plate 2, a pair of first side plates 3 (corresponding to "side plates" in this embodiment) connected to each of a pair of opposing edges (left and right edges) of the bottom plate 2, a pair of second side plates 4 and 5 (corresponding to "end plates" in this embodiment) connected to each of another pair of opposing edges (front and rear edges) of the bottom plate 2, a pair of first flaps 6 (corresponding to "inner flaps" in this embodiment) connected to each of the pair of first side plates 3, and a pair of inner flaps 6 connected to the second side plates 4 and overlapping the first flaps 6. The second flap 7 has a second flap 7 (corresponding to the "inner flap" in this embodiment) connected to the second side panel 5 and overlapping the first flap 6 and the second flap 7, a third flap 8 (corresponding to the "outer flap" (top panel) in this embodiment) connected to the second side panel 5 and overlapping the first flap 6 and the second flap 7, a pair of fourth flaps 9 (corresponding to the "inner flaps" in this embodiment) connected to each of a pair of opposing end edges (left and right edges) of the third flap 8, an insertion portion 10 connected to the end edge of the third flap 8, and a locking piece 20 formed on the second flap 7.

[0033] The packaging box 1 has a locking structure when sealed, in which the second flap 7 (insertion receiving side) is provided with a pair of insertion openings 72 (corresponding to the "insertion slits" of the present invention) along the second flap fold line, and a lock piece 20 located between the pair of insertion openings 72 with both side ends adjacent to the pair of insertion openings 72, and a lock piece insertion opening 11 is provided at the base end of an insertion portion 10 connected to the third flap 8, which serves as the top plate, via the insertion portion fold line b6, into which the lock piece 20 can be inserted.

[0034] As shown in Fig. 2, the packaging box 1 is made of a substantially rectangular cardboard paperboard 1X. The center of the paperboard 1X in Fig. 2 becomes the bottom plate 2 of the packaging box 1 when assembled into the packaging box 1 as shown in Fig. 1, both sides of the bottom plate 2 in the left-right direction (left-right direction in Fig. 2) become first side plates 3 of the packaging box 1 when assembled into the packaging box 1 as shown in Fig. 1, and both sides of the bottom plate 2 in the up-down direction (up-down direction in Fig. 2) become second side plates 4 and 5 of the packaging box 1 when assembled into the packaging box 1 as shown in Fig. 1. In addition, a third flap 8 connected to the second side plate 5 becomes the top plate of the packaging box 1 when assembled into the packaging box 1 as shown in Fig. 1.

[0035] As shown in FIG. 2, a first fold line a1 is formed on the paperboard 1X, separating the bottom plate 2 from the first side plate 3. The bottom plate 2 and the first side plate 3 are connected via this first fold line a1. A second fold line a2 is also formed on the paperboard 1X, separating the bottom plate 2 from the second side plates 4 and 5. The bottom plate 2 and the second side plates 4 and 5 are connected via this dividing fold line a2. The first fold line a1 and the second fold line a2 are formed, for example, by making cuts in the crease. This makes it easier to fold the paperboard 1X (blank sheet). In this embodiment, the height of the first side plate 3 (width in the left-right direction in FIG. 2) is approximately the same as the height of the second side plates 4 and 5 (width in the up-down direction in FIG. 2).

[0036] A side panel flap 31 is provided at one end (the lower end in FIG. 2) of the first side panel 3 via a fold line c1. A folding flap 32 is provided at the other end (the upper end in FIG. 2) of the first side panel 3 via a fold line c2. This folding flap 32 is connected to the end of the second side panel 5 via a fold line c3. A fold line c4 is formed on one diagonal of the folding flap 32. The side panel flap 31 is formed so that when it is folded along the fold line c1 and superimposed on the second side panel 4, it fits in a position between the lower edge and the upper edge of the second side panel 4.

[0037] Furthermore, a first flap fold line b1 is formed on the paperboard 1X, separating the first flap 6 from the first side panel 3. The first flap 6 and the first side panel 3 are connected via this first flap fold line b1. The paperboard 1X also has a second flap fold line b2, separating the second flap 7 from the second side panel 4, and the second flap 7 and the second side panel 4 are connected via this second flap fold line b2. Connecting flaps 71 are connected to both sides of the second flap 7 in the left-right direction (left-right direction in FIG. 2) via connecting flap fold lines b4. The tip of the connecting flap 71 is formed in a substantially arc shape. Furthermore, a third flap fold line b3 is formed, separating the third flap 8 from the second side panel 5, and the third flap 8 and the second side panel 5 are connected via this third flap fold line b3. Furthermore, fourth flaps 9 are connected to both sides of the third flap 8 in the left-right direction (left-right direction in FIG. 2) via fourth flap fold lines b5. Cut lines d1 and d2 are formed at both ends of the fourth flap fold line b5. The lower end (the lower end in FIG. 2) of the fourth flap 9 is connected to the folding flap 32 via fold line c5. Furthermore, an insertion portion 10 is connected to the edge of the third flap 8 via an insertion portion fold line b6. Note that the first flap fold line b1, the second flap fold line b2, and the third flap fold line b3 are also formed by cutting into the crease lines to make folding easier.

[0038] The first flap 6 is formed with a cut line 61 and a connecting slit 62 that extend parallel to the first flap fold line b1. The cut line 61 has approximately the same length as the fourth flap fold line b5, and is formed so that both ends are connected to the first flap fold line b1. The cut line 61 creates a notch in the first flap 6, forming a protrusion that corresponds to the first side panel 3. The connecting slit 62 is shaped so that the connecting flap 71 can be inserted when the packaging box 1 is assembled.

[0039] The second flap 7 is provided with a pair of insertion openings 72 along the second flap fold line b2, and a locking piece 20 located between the pair of insertion openings 72, with both side ends adjacent to the pair of insertion openings 72. The locking piece 20 is surrounded by a locking piece fold line 21 formed at a position away from the second flap fold line b2 toward the second side panel 4 (for example, a distance equivalent to one thickness of a corrugated cardboard sheet 1X), and a locking piece breakable line 22 connecting both ends of the locking piece fold line 21 and extending in a direction away from the locking piece fold line 21 and toward the edge of the second flap 7, the locking piece 20 having a breakable connecting portion 22a at at least one location. The connecting portion 22a is formed so that when the packaging box 1 is assembled, the insertion portion 10 is inserted into the pair of insertion openings 72 and can be broken by the pressing force of the insertion portion 10. Furthermore, locking portions 73 formed by cut lines and crease lines are provided on the outer edge sides of each of the pair of insertion openings 72 (the left and right edges in FIG. 2). These locking portions 73 are formed so as to be bent inward and engage with the return portions 12 of the insertion portion 10 when the insertion portion 10 is inserted into the pair of insertion openings 72. The width of the pair of insertion openings 72 is designed appropriately depending on the thickness of the insertion portion 10 to be inserted. In some cases, the pair of insertion openings 72 may be formed by a pair of cut lines along the second flap fold line b2.

[0040] The third flap 8 functions as a top plate of the packaging box 1. In this embodiment, the insertion portion 10 is connected to the edge of the third flap 8 via a pair of insertion portion fold lines b6. The insertion portion fold lines b6 are provided on both sides of the locking piece insertion opening 11, and each is formed so as to extend diagonally from the outer end (the outer end in the left-right direction in FIG. 2 ) to the center and away from the edge of the third flap 8. In addition, the base end of the insertion portion 10 is provided with the locking piece insertion opening 11 extending parallel to the edge of the third flap 8. This locking piece insertion opening 11 is formed at a position away from the edge of the third flap 8 toward the insertion portion 10 by a predetermined distance (for example, a distance equivalent to one thickness of a corrugated cardboard 1X) toward the insertion portion 10. In addition, both sides of the base end of the insertion portion 10 are provided with return portions 12 that can prevent the insertion portion 10 from slipping out when inserted into the pair of insertion openings 72 of the second flap 7. Furthermore, a pair of insertion guide portions 13 having a convex shape that allows for easy insertion into a pair of insertion openings 72 of the second flap 7 are formed at the tip of the insertion portion 10. A recess 14 is formed between the pair of insertion guide portions 13, and the center of the edge of this recess 14 is formed so as to slightly protrude from both sides.

[0041] The third flap 8 is also provided with finger holes 81 for placing fingers when opening the packaging box, and breakable lines 82 extending from both side edges of the finger holes 81 to the outer edges of the pair of insertion portion fold lines b6. The finger holes 81 are formed in a portion of the third flap 8 that overlaps with the second flap 7 when the packaging box 1 is sealed. This makes it possible to prevent the contents of the packaging box 1 from being exposed to the outside.

[0042] The steps of assembling and sealing the packaging box 1 of this embodiment will be described below with reference to FIGS.

[0043] In the process of assembling the packaging box 1 from the paperboard 1X, first, as shown in FIG. 3 , the pair of first side panels 3 are each folded upward at approximately 90° along the first fold line a1 relative to the bottom panel 2. The second side panel 5 is also folded upward at approximately 90° along the first fold line a1 relative to the bottom panel 2. At this time, the folding flaps 32 are folded along fold lines c2, c3, and c4. Furthermore, the pair of first flaps 6 are each folded inward at approximately 90° along the first flap fold line b1 relative to the first side panel 3. The pair of side panel flaps 31 are each folded inward at approximately 90° along the fold line c1 relative to the first side panel 3. Then, the pair of fourth flaps 9 are each folded inward at approximately 180° along the fourth flap fold line b5 and overlapped with the third flap 8.

[0044] Next, as shown in FIG. 4 , the second side panel 4 is folded upward at approximately 90° along the first fold line a1 relative to the bottom panel 2. The pair of connecting flaps 71 are also folded inward at approximately 90° along the connecting flap fold line b4 relative to the second flap 7. The second flap 7 is then folded inward at approximately 90° along the second flap fold line b2, and the pair of connecting flaps 71 are inserted into the connecting slits 62. This causes the second flap 7 to overlap the first flap 6, and the second side panel 4 is connected to the pair of first side panels 3. In this embodiment, the lock piece breakable line 22 of the lock piece 20 has a breakable connecting portion 22a in at least one location, and the lock piece fold line 21 is formed at a position a predetermined distance away from the second flap fold line b2 toward the second side plate 4. Therefore, when the second flap 7 is folded inward at approximately 90°, the lock piece 20 assumes an inclined position (see FIGS. 4 and 8) between the second side plate 4 and the second flap 7. As a result, when the packaging box 1 is assembled, the connecting portion 22a can be easily broken by the pressing force of the insertion portion 10 when the insertion portion 10 is inserted into the pair of insertion openings 72.

[0045] Next, as shown in Fig. 5, first, the insertion portion 10 is folded inward at approximately 90° along a pair of insertion portion crease lines b6 relative to the third flap 8. In this embodiment, the insertion portion crease lines b6 are provided on both sides of the lock piece fitting opening 11, and are formed so that each extends obliquely from the outer end to the center and away from the edge of the third flap 8. Therefore, when the insertion portion 10 is folded along the insertion portion crease lines b6, the insertion portion 10 is folded inward from the direction perpendicular to the third flap 8 (see Fig. 8). As shown in Fig. 8, when the insertion portion 10 is folded, the insertion portion 10 is folded inward (for example, at an angle α) from the direction perpendicular to the third flap 8. Therefore, when the insertion portion 10 is pressed downward and inserted, the tip of the insertion portion 10 is biased toward the lock piece breakable line 22 of the lock piece 20 and presses, easily breaking the connecting portion 22a of the lock piece breakable line 22. Next, the third flap 8 is folded inward relative to the second side panel 5 along the third flap fold line b3.

[0046] Next, as shown in Fig. 6, the third flap 8 is folded inward at approximately 90° along the third flap fold line b3 relative to the second side plate 5, and the insertion portion 10 is inserted into the pair of insertion openings 72 of the second flap 7. Furthermore, by pressing the insertion portion 10 downward, the recess 14 of the insertion portion 10 breaks the connecting portion 22a of the lock piece breakable line 22 of the lock piece 20, and the entire insertion portion 10 is inserted inside the second side plate 4. As a result, the tip of the lock piece 20 is fitted into the lock piece fitting opening 11 of the insertion portion 10. The tip of the lock piece 20 fitted into the lock piece fitting opening 11 is engaged by being in surface contact with the underside of the second flap 7 (see Fig. 8). Furthermore, when the insertion portion 10 is inserted into the pair of insertion openings 72, the locking portions 73 formed on the outer edge sides of each of the pair of insertion openings 72 are bent inward and engage with the return portions 12 of the insertion portion 10, thereby locking the insertion portion 10 and preventing it from coming loose. This allows the packaging box 1 to be assembled and sealed. The sealed packaging box 1 is in the state shown in FIG. 1. FIG. 7 shows an enlarged view of the locking portion after the packaging box 1 has been sealed. As shown in FIG. 7, after sealing, the locking piece 20 cannot be removed, and the third flap 8 is held firmly locked. In this way, sealing with tape is not required, and the packaging box 1 can be easily assembled and sealed.

[0047] The operation when opening the packaging box 1 of this embodiment and the state after opening will be described below with reference to Figures 9 and 10. Figure 9 shows the operation state when opening the packaging box 1. Figure 10 shows the state when discarding the packaging box 1 after opening.

[0048] When opening the packaging box 1 of this embodiment, a user first inserts his or her fingers into the finger holes 81 and pushes the second flap 7 of the packaging box 1 inward with the fingers, while simultaneously grabbing the edge of the finger hole 81 with the hand and pulling it up. During the pulling process, the second flap 7 is cut along the two breakable lines 82 connected to both ends of the finger hole 81, and as shown in FIG. 9 , the area between the two breakable lines 82 is separated from the third flap 8 together with the insertion portion 10. This makes it possible to open the third flap 8. That is, with the third flap 8 locked by the locking piece 20, the packaging box 1 can be opened easily and quickly.

[0049] Furthermore, after opening the packaging box 1, when it is discarded as a disposal piece 1Y, as shown in Figure 10, the area between the breakable lines 82 that are cut away from the third flap 8 by the opening operation and the insertion portion 10 connected thereto remain locked by the locking piece 20 and the return portion 12, and are connected to the second flap 7. Therefore, when the packaging box 1 is discarded after opening, there is only one disposal piece 1Y, which makes disposal easy.

[0050] Next, the effects of this embodiment will be described.

[0051] In the packaging box 1 of this embodiment, the locking structure includes a pair of insertion openings 72 along the second flap fold line b2 in the second flap 7, and locking pieces 20 located between the pair of insertion openings 72 with both side ends adjacent to the pair of insertion openings 72. The locking pieces 20 are surrounded by a locking piece fold line 21 formed at a position spaced apart from the second flap fold line b2 toward the second side panel 4 by a distance equivalent to one thickness of the paperboard 1X, and a locking piece breakable line 22 connecting both ends of the locking piece fold line 21 and extending in a direction away from the locking piece fold line 21 and toward the edge of the second flap 7, the locking piece breakable line 22 having at least one breakable connecting portion 22a. For example, the locking piece breakable line 22 is a cut line cut in one position in the center and having the connecting portion 22a that can break when the insertion portion 10 is inserted into the pair of insertion openings 72. In addition, an insertion portion 10 is provided which is connected to the edge of the third flap 8 via the insertion portion fold line b6 and can be inserted into a pair of insertion openings 72, and a lock piece insertion opening 11 into which a lock piece 20 can be inserted is provided at the base end of the insertion portion 10.When the box is sealed, the insertion portion 10 on the third flap 8 (which functions as a lid) is inserted into the pair of insertion openings 72 of the second flap 7, and the lock piece 20 on the second flap 7 is inserted into the lock piece insertion opening 11 provided at the base end of the insertion portion 10.

[0052] According to this configuration, when the second flap 7 is folded along the second flap fold line b2 during sealing, the locking piece 20 assumes an inclined position between the second side panel 4 and the second flap 7. When the insertion portion 10 on the third flap 8 is inserted into the pair of insertion openings 72 of the second flap 7, the pushing force of the insertion portion 10 pushes the tip of the locking piece 20 downward, breaking the connecting portion 22a. As the insertion portion 10 is further inserted, the tip of the locking piece 20 enters the locking piece fitting opening 11 provided at the base end of the insertion portion 10, and the upper surface of the tip of the locking piece 20 comes into surface contact with the lower surface of the second flap 7 and is locked. As a result, after sealing, the insertion portion 10 is locked and the locking piece 20 cannot be removed, so the third flap 8 can be maintained in a firmly locked state and tampering or other unauthorized opening can be prevented.

[0053] Furthermore, in the packaging box 1 of this embodiment, the opening of the box body can be tightly closed without taping, and since it does not have a movable flap connected to the locking piece like the locking mechanism of Patent Document 1 mentioned above, the locking piece 20 cannot be removed after the box is sealed, which prevents unauthorized unlocking and opening.

[0054] Therefore, according to the packaging box 1 of this embodiment, the box can be sealed without using tape, which reduces the amount of work required and is environmentally friendly. After sealing, the third flap 8 serving as the lid can be kept firmly locked, preventing it from being opened improperly by tampering or the like.

[0055] Furthermore, in the packaging box 1 of this embodiment, the insertion portion fold line b6 is provided on each side of the lock piece insertion opening 11, and each is formed so as to extend diagonally from the outer end to the center and away from the edge of the third flap 8. Therefore, when the insertion portion 10 is folded along the insertion portion fold line b6 during sealing, the insertion portion 10 is folded inward from a direction perpendicular to the third flap 8, and therefore the connecting portion 22a of the lock piece breakable line 22 of the lock piece 20 can be easily broken.

[0056] Therefore, in the packaging box 1 of this embodiment, when folding the insertion portion 10 along the insertion portion crease line b6 during sealing, the insertion portion 10 is folded inward from a direction perpendicular to the third flap 8, which makes it possible to easily break the connecting portion 22a of the lock piece breakable line 22 of the lock piece 20. Therefore, the locking operation during sealing can be performed smoothly.

[0057] Furthermore, in the packaging box 1 of this embodiment, the insertion portion 10 is provided with return portions 12 on both sides of the base end thereof to prevent it from coming off when inserted into the pair of insertion openings 72. After the insertion portion 10 is inserted into the pair of insertion openings 72, the return portions 12 are locked with the locking portions 73 on the outer ends of the insertion openings, forming a double lock structure together with the locking pieces 20, making it difficult for the insertion portion 10 to come off. This allows the third flap 8 to be held in a more secure locked state, reliably preventing it from being opened illicitly by tampering or the like.

[0058] Therefore, according to the packaging box 1 of this embodiment, the lock is difficult to release after sealing due to the double lock structure of the lock piece 20 and the return part 12. Therefore, the third flap 8 can be maintained in a more secure locked state, and it is possible to reliably prevent the box from being opened improperly by tampering or the like.

[0059] In addition, in the packaging box 1 of this embodiment, an insertion guide portion 13 is formed at the tip of the insertion portion 10, so that when sealing the box, the tip of the insertion portion 10 can be easily inserted into a pair of insertion openings 72, allowing the sealing operation to be carried out smoothly.

[0060] Therefore, according to the packaging box 1 of this embodiment, the leading ends of the insertion portions 10 can be easily inserted into the pair of insertion openings 72 when sealing the box, thereby improving workability.

[0061] Furthermore, in the packaging box 1 of this embodiment, the third flap 8 is provided with a finger hole 81 for hooking a finger when opening, and a pair of breakable lines 82 extending from both side edges of the finger hole 81 to both ends of the insertion portion fold line b6, so that when opening, the third flap 8 can be opened by hooking a fingertip into the finger hole 81 and pulling it, thereby breaking the breakable lines 82 extending from both side edges of the finger hole 81 to both ends of the insertion portion fold line b6. This allows the packaging box 1 to be opened easily and quickly while locked by the lock piece 20.

[0062] Furthermore, in the packaging box 1 of this embodiment, when the box is opened, a portion of the third flap 8 that is broken along the breakable line 82 is connected to the locking piece 20 via the insertion portion 10, so that the insertion portion 10 remains locked even after opening, and there is only one disposal piece 1Y, making disposal easier.

[0063] Therefore, the packaging box 1 of this embodiment can be opened easily and quickly while locked by the locking piece 20. Furthermore, because a portion of the torn third flap 8 is connected to the locking piece 20 via the insertion portion 10, the insertion portion 10 remains locked even after opening, and there is only one discardable piece 1Y, making disposal easy. This eliminates the problem of the conventional packaging box where the torn portion becomes separated from the main body upon opening, resulting in an increase in discardable pieces.

[0064] Next, a modified example of the packaging box 1 of this embodiment will be described.

[0065] In the packaging box 1 according to the embodiment described above, the lock piece frangible line 22 of the lock piece 20 is an example of a cut line that is cut in one place in the center and has connecting portions 22a that can be broken when the insertion portion 10 is inserted into the pair of insertion openings 72, but the present invention is not limited to this. For example, the lock piece frangible line 22 may be formed by forming a plurality of short cuts discontinuously with short connecting portions interposed therebetween (perforated line).

[0066] According to this configuration, when the second flap 7 is folded along the second flap fold line b2 during sealing, the locking piece 20 is inclined between the second side panel 4 and the second flap 7. When the insertion portion 10 on the third flap 8 is inserted into the pair of insertion openings 72 of the second flap 7, the pushing force of the insertion portion 10 pushes the tip of the locking piece 20 downward, breaking the connecting portion of the perforation line. As the insertion portion 10 is further inserted, the tip of the locking piece 20 enters the locking piece insertion opening 11 provided at the base end of the insertion portion 10, and the tip of the upper surface of the locking piece 20 is locked by surface contact with the underside of the second flap 7. As a result, the locking piece 20 cannot be removed after sealing, the third flap 8 is maintained in a securely locked state, and tampering or other unauthorized opening can be prevented.

[0067] In the above-described embodiment, the packaging box 1 is described as a packaging box that can be dropped into a postbox, but the present invention is not limited to this. The present invention can also be applied to packaging boxes other than those that can be dropped into a postbox.

[0068] Furthermore, in the above-described embodiment, an example was described in which the second flap 7 is superimposed on top of a pair of first flaps 6 when folded along the second flap fold line b2, but the present invention is not limited to this.

[0069] Furthermore, in the above-described embodiment, the material is explained as being corrugated cardboard, but the material may be cardboard or a thin synthetic resin plate as long as it can be folded and assembled.

[0070] The present invention is not limited to the above-described embodiments, and its technical scope includes various modified design forms within the scope that do not deviate from the gist of the invention described in the claims. [Explanation of symbols]

[0071] 1 packaging box 2 Bottom plate 3 1st side plate 4, 5 Second side plate 6 First flap 7 Second flap 8. Third flap 9 Fourth flap 10 Insertion part 11 Lock piece insertion opening 12 Return part 13 Insertion guide 14 Recess 20 Lock piece 21 Lock piece fold line 22 Lock piece breakable line (notch line) 22a Joint 31 Side panel flap 32 Folding flap 61 Cut line 62 Connecting slit 71 Connecting flap 72 Insertion opening (insertion slit) 73 Locking part 81 Finger hole 82 Breakable Line a1 First fold line a2 2nd fold line b1 First flap fold line b2 Second flap fold line b3 Third flap fold line b4 Connecting flap fold line b5 4th flap fold line b6 Insertion part fold line c1, c2, c3, c4, c5 crease line d1, d2 cutting lines

Claims

1. A rectangular bottom plate; a pair of first side plates connected to a pair of opposing end edges of the bottom plate via first fold lines; a pair of second side plates connected to a pair of opposing edges of the bottom plate in a direction intersecting the opposing direction of the first side plates via second fold lines; a pair of first flaps connected to upper edges of the pair of first side plates via first flap fold lines; a second flap connected to an upper edge of one of the pair of second side plates via a second flap fold line; a third flap connected to an upper edge of the other of the pair of second side panels via a third flap fold line and overlapping the first flap and the second flap, The second flap is provided with a pair of insertion slits along the second flap fold line, and a lock piece located between the pair of insertion slits, with both side ends adjacent to the pair of insertion slits, The locking piece is surrounded by a locking piece fold line formed at a position a predetermined distance away from the second flap fold line toward the second side panel, and a locking piece breakable line connecting both ends of the locking piece fold line and extending in a direction away from the locking piece fold line and toward the edge of the second flap, and having a breakable connecting portion at at least one location, The packaging box is characterized in that an insertion portion is provided at the end edge of the third flap, connected via an insertion portion fold line, and can be inserted into the pair of insertion slits, and a lock piece insertion opening is provided at the base end of the insertion portion, into which the lock piece can be fitted.

2. The packaging box according to claim 1, The packaging box is characterized in that the insertion portion fold lines are provided on both sides of the lock piece insertion opening, and each is formed to extend diagonally from the outer end to the center and away from the edge of the third flap.

3. The packaging box according to claim 1 or 2, A packaging box characterized in that a return portion is provided on both sides of a base end of the insertion portion to prevent the insertion portion from slipping out when the insertion portion is inserted into the pair of insertion slits.

4. The packaging box according to claim 1 or 2, A packaging box characterized in that an insertion guide portion having a convex shape that makes it easy to insert the insertion portion into the pair of insertion slits is formed at the tip of the insertion portion.

5. The packaging box according to claim 1 or 2, The lock piece breakable line is a cut line that is cut at one point in the center and has a connecting portion that can be broken when the insertion portion is inserted into the pair of insertion slits.

6. The packaging box according to claim 1 or 2, The packaging box is characterized in that the third flap is provided with a finger hole for placing fingers when opening the box, and a pair of breakable lines extending from both side ends of the finger hole to both outer ends of the fold line of the insertion portion.

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