JP5214661B2 - Plastic folding box - Google Patents

Description

  The present invention is, for example, a folding box for storing commodities such as foods and pharmaceuticals, which can be easily folded and can be stored in a stable state without falling down the stored items. About.

  As this type of folding box, for example, the following paper containers are known (see Patent Document 1). That is, such a paper container has four bottom plates formed by bending inward from the lower end of the side plate, and the shape surrounded by the four side plates has a square shape. Of these four bottom plates, the two bottom plates located inside are in contact with the inner surfaces of the two bottom plates located outside. And on the line from the side edge of the outer bottom plate surface that contacts the diagonally two locations of the four bottom plates to the tip side and on the line from the side edge of the inner bottom plate to the tip side A bent portion is formed. Furthermore, the front end triangular surface of the outer bottom plate having the bent portion as one side is bonded to the inner bottom plate surface contacting the surface corresponding to this surface.

  According to this paper container, it is possible to assemble the paper container with a single touch and to restore the original folded shape again.

JP-A-6-122440

  However, in the paper container described in Patent Document 1, since the bottom plate on the inner surface side is composed of two bottom plates, a step is formed there when the two bottom plates are not abutted. On the other hand, even when they are abutted, a slight level difference is likely to occur between the bottom plates when the contents are accommodated in the paper container or when the box is assembled. Furthermore, in that case, precise dimensional accuracy is required, and because of this precision, there is a possibility that a gap may be generated due to the influence of heat, moisture, etc. or material deformation due to repeated use, or conversely two sheets There is a risk that the bottom plates of the two parts overlap to form a step. And when the level | step difference etc. which were mentioned above have arisen, a level | step difference etc. will result in the wide range of a box bottom center part. For this reason, there is a problem that when the stored item is stored in the paper container, the stored item is inclined or falls at the step portion, and it is difficult to cleanly and efficiently store the stored item.

  Therefore, the object of the present invention is to make the assembly and folding smoothly and to be able to accommodate the stored item in a more stable state without tilting or falling down. It is to provide a folding box.

To achieve the above object, the resin folding box according to the first aspect of the present invention is configured such that four side plates are integrally formed via folding lines provided at the four corners, and the folding lines are formed at the lower end edges of the side plates. The bottom plate is connected via the inner plate, and the innermost inner bottom plate of the bottom plates is connected to one side plate and disposed on the entire bottom surface, and the outer bottom plate connected to the other side plates supports the inner bottom plate. The folding lines provided at the four corners are folded by folding lines that are not adjacent to each other. Then, a fold line extending obliquely from one end of the fold line connecting the inner bottom plate and the side plate toward the opposite side of the inner bottom plate facing the fold line is formed, and the inner bottom plate is inclined when the box is folded. It is configured to be folded outward or inward by a fold line extending inward, and the angle of the side folded between the outer side or the inner side formed by the diagonally extending fold line and the opposite side is 67.5 to 75.0 ° A fold line that is set and extends obliquely from the other end of the fold line that connects the outer bottom plate and the side plate toward the opposite side of the outer bottom plate facing the fold line is formed .

  A resin folding box according to a second aspect of the present invention is the resin folding box according to the first aspect, wherein the folding line extending in the oblique direction is in contact with one end of a vertical folding line connecting the inner bottom plate and the side plate, and one end thereof. When a circle having a center is drawn on a line orthogonal to the vertical folding line, the circle is formed so as to extend in the tangential direction of the circle, and the radius of the circle is set within 4 mm.

A resin folding box according to a third aspect of the present invention is characterized in that, in the invention according to the first or second aspect, the folding line is formed by hot pressing.
A resin folding box according to a fourth aspect of the present invention is characterized in that, in the invention according to the third aspect, the width of the folding line is set to 7 to 15 mm.

  A resin folding box according to a fifth aspect of the present invention is the invention according to any one of the first to fourth aspects, wherein the outer bottom plate is one of the outer bottom plates on both sides adjacent to the inner bottom plate when unfolded. Forming an oblique fold line from one end of the fold line, joining the inner bottom plate side of the oblique fold line to the outer surface of the inner bottom plate as a first joint, and forming the fold line on the other outer bottom plate A diagonal fold line is formed from the other end of the fold line located diagonally with the one end of the outer bottom plate, and the outer bottom plate side facing the inner bottom plate is joined to the outer surface of the outer bottom plate from the diagonal fold line. A slanted fold line is provided on the second joint portion side of the outer bottom plate that faces the inner bottom plate and that allows the outer bottom plate to be folded inward.

  A resin folding box according to a sixth aspect of the present invention is the invention according to any one of the first to fifth aspects, wherein the two adjacent side plates, the inner bottom plate and the outer bottom plate connected thereto, and the like Two side plates adjacent to each other and an outer bottom plate connected to the side plates are joined by an ear plate provided on the side plate.

  The resin folding box of the invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein a lid plate is connected to each side plate via a folding line. Features.

According to the present invention, the following effects can be exhibited.
In the resin folding box of the present invention, a folding line extending in an oblique direction from one end portion of the folding line connecting the inner bottom plate and the side plate toward the opposite side of the inner bottom plate facing the folding line is formed. The inner bottom plate is configured to be folded outward or inward by a folding line extending in an oblique direction. For this reason, when opening and assembling the folded box, the inner bottom plate folded by the folding line extending in the oblique direction is flattened by opening the side plate so as to have a flat square shape, and the entire bottom surface is covered. Be placed. On the other hand, when the assembled box is folded, the inner bottom plate is folded along a folding line extending in an oblique direction.

In this case, since the angle of the outer side or the inner side formed by the folding line extending in the oblique direction and the opposite side is set to 67.5 to 75.0 °, an operation for assembling or folding the box Can be performed smoothly. Since the assembled box has an inner bottom plate on the entire bottom surface thereof, it is avoided that the contents in the box become unstable.
In addition, since a fold line extending obliquely from the other end of the fold line connecting the outer bottom plate and the side plate toward the opposite side of the outer bottom plate facing the fold line is formed, When folded, the outer bottom plate can be folded along its fold line.

  Therefore, according to the resin folding box of the present invention, assembling and folding can be performed smoothly, and the stored items can be stored in a more stable state without tilting or falling down. .

The perspective view which shows the state which assembled the resin folding box in embodiment of this invention, and the cover plate opened. (A) is a front view which shows the state which folded the resin folding box, (b) is a top view which shows the state which folded the resin folding box. The perspective view which shows the state which opened the folded resin folding box a little. The perspective view which shows the state which further opened the resin folding box from the state of FIG. The perspective view which shows the state which looked at the resin folding box of the state of FIG. 4 from the bottom face side. (A) is the perspective view which shows the state which looked at the resin folding box of the assembled state from the top side, (b) is the perspective view which shows the state which looked at the assembled resin folding box from the bottom side . The expanded view which is the state which expand | deployed the resin folding box, and shows the 1st structural member which has an inner side bottom plate. The expanded view which is the state which expand | deployed the resin folding box, and shows the 2nd structural member which has an outer side bottom plate. The partial expansion expanded view which expands and shows the part of the folding line extended in the diagonal direction and the one end part of the folding line which connects an inner side bottom plate and a long side board. (A) is a perspective view which shows the board | plate material which comprises resin-made folding boxes, (b) is sectional drawing which shows the vicinity part of a fold line, (c) is sectional drawing which shows the vicinity part of each edge part.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments embodying the present invention will be described in detail with reference to FIGS.
As shown in FIG. 1, the resin folding box 10 of the present embodiment has four side plates 11 bent at right angles by folding lines 12 provided at four corners, and ear plates 13 provided at diagonal positions of the side plates 11. Are integrally formed by joining. A bottom plate 14 is connected to the lower edge of each side plate 11 via a fold line 12, and a lid plate 15 is connected to each side plate 11 via a fold line 12, so that the resin folding box 10 forms a flat rectangle. It is formed in a square box shape. A gripping hole 16 for gripping the box is opened at the center upper portion of the short side plate 11b on the short side facing each other. And it folds | folds by the folding line 12 of the two corners which are not adjacent among the folding lines 12 provided in the four corners.

  As shown in FIGS. 1 and 7, the innermost bottom plate 14a located on the innermost side of the bottom plate 14 is connected to one long side plate 11a on the long side and is disposed on the entire surface of the bottom portion. A long side outer bottom plate 14b and a short side outer bottom plate 14b connected to the side plate 11a and the short side plate 11b are configured to support the inner bottom plate 14a. An oblique fold line 12a extending in an oblique direction from one end portion 12c of the fold line 12 connecting the inner bottom plate 14a and the long side plate 11a toward the opposite side 14c of the inner bottom plate 14a facing the fold line 12 is formed. When the box is folded, the inner bottom plate 14d positioned on the outer bottom plate 14b side closer to the shorter side than the diagonal fold line 12a is configured to be folded outward by the diagonal fold line 12a.

  An angle θ of the side folded on the outer side (the inner bottom plate 14d side) formed by the diagonal fold line 12a and the opposing side 14c is set to 67.5 to 75.0 °, and the inner bottom plate 14d is the diagonal fold line 12a. It can be folded smoothly. When the angle θ is smaller than 67.5 °, the inner bottom plate 14d interferes with another bottom plate 14 when the box is folded. On the other hand, when the angle θ is larger than 75.0 °, the inner bottom plate 14d (including the bent end portion of the oblique folding line 12a) easily interferes with the side plate 11 when the box is folded, and the box can be folded smoothly. Can not be done.

  As shown in FIG. 9, the diagonal fold line 12a is in contact with one end 12c of the fold line 12 connecting the inner bottom plate 14a and the long side plate 11a, and is centered on a line 17 perpendicular to the fold line 12 from the one end 12c. When a circle 18 having a circle is drawn, the circle 18 is formed so as to extend in a tangential direction. The radius r of the circle 18 is set within 4 mm, and the smooth folding of the inner bottom plate 14a along the oblique folding line 12a is allowed by setting the radius r within the range. When the radius r exceeds 4 mm, the inner bottom plate 14d on the side that is folded outward from the oblique fold line 12a overlaps the outer bottom plate 14b on the short side, so that folding becomes difficult. The range of the radius r is more preferably in the range of 0.5 to 4 mm. Darely, by shifting the position from the one end portion 12c, smoother folding and assembling operations can be obtained.

  As shown in FIGS. 1 and 7, when the box is unfolded, the outer bottom plate 14b on the short side adjacent to the inner bottom plate 14a is formed with an oblique fold line 12b from one end 12c of the fold line 12, The inner bottom plate 14a side from the oblique fold line 12b is joined to the outer surface of the inner bottom plate 14a to form a right triangle-shaped first joining portion 19. 5 and 8, when the box is assembled, the outer bottom plate 14b on the short side adjacent to the outer bottom plate 14b on the short side facing the inner bottom plate 14a is connected to the other end 12d of the fold line 12. Are formed on the outer bottom plate 14b on the longer side than the inclined folding line 12b and joined to the outer surface of the outer bottom plate 14b on the longer side. It is comprised so that it may be formed. An oblique fold line 12a is formed from the other end portion 12d of the fold line 12 of the long side outer bottom plate 14b, and the outer bottom plate 14e located on the second joint 20 side of the outer bottom plate 14b is the oblique fold line 12a. It can be folded to the outside.

  The side plate 11, the bottom plate 14, the cover plate 15, etc. constituting the resin folding box 10 are all formed to a thickness of about 3 to 50 mm by a thermoplastic resin such as a polypropylene resin, a polyethylene resin, or a polycarbonate resin. As shown in FIG. 10 (a), the side plate 11, the bottom plate 14, the lid plate 15 and the like have a large number of parallel ribs 23 laid at regular intervals between a pair of liners 21 and 22 arranged to face each other. 24 is a plate material. Therefore, the resin folding box 10 can exhibit higher strength than the paper folding box, and can be lightweight because it has the hollow portion 24.

  As shown in FIG. 10 (b), the folding line 12 is heated and welded (fused) by, for example, hot pressing to sandwich the plate 21 having the hollow portion 24 from above and below the opposing liners 21 and 22 with a heating plate (not shown). ). Further, as shown in FIG. 10C, the end seal portion 28 can also be formed by a method such as hot pressing as with the folding line 12. In addition, as a method of forming the fold line 12 and the seal portion 28, a method of irradiating the fold line 12 with ultrasonic waves and heat-welding, and cutting one liner 21 at the fold line 12, and a hinge member there , A method of forming a bent groove with a heated V-shaped blade or the like in a state in which a thermoplastic resin reinforcing core material is loaded in the hollow portion 24, and pressing a portion of the fold line 12 with a heated V-shaped blade Then, a method of forming the V-groove while melting the liners 21 and 22, a method of leaving a single liner 22, and a method of making a cut in the fold line 12.

  When the fold line 12 is formed by the hot pressing, the fold line 12 has a width of 7 to 15 mm and a thickness of about 0.1 to 3 mm. In the case where the width of the fold line 12 is narrower than 7 mm, when the fold line 12 is folded, the bent portion is bent at an acute angle and weakened, and the durability against repeated assembly and folding of the box is lowered. On the other hand, when the width of the fold line 12 is wider than 15 mm, there is a width at the position where the fold line 12 is folded, and it is not preferable because it is slightly tilted and the assembly accuracy deteriorates.

  The resin folding box 10 of the present embodiment is integrated by melting and joining the first structural member 25 as shown in FIG. 7 and the second structural member 26 as shown in FIG. It is comprised so that it may be formed. As shown in FIG. 7, the first structural member 25 includes an adjacent long side plate 11a and short side plate 11b, an inner bottom plate 14a, an ear plate 13 and a lid plate 15 connected to the long side plate 11a via a fold line 12. The outer side plate 14b on the short side and the cover plate 15 having the first joint portion 19 connected to the short side plate 11b via the fold line 12 are configured. A cut 27 is provided between the inner bottom plate 14d and the first joint portion 19, so that the inner bottom plate 14d and the first joint portion 19 can be bent independently. Cuts 27 are also provided between the cover plates 15 so that both the cover plates 15 can be bent independently.

  On the other hand, as shown in FIG. 8, the second structural member 26 includes an adjacent long side plate 11a and short side plate 11b, a long side side outer bottom plate 14b connected to the long side plate 11a via a fold line 12, and an ear plate. 13 and a cover plate 15, and a short side outer bottom plate 14 b and a cover plate 15 having a second joint 20 connected to the short side plate 11 b via a fold line 12. A cut 27 is provided between the outer bottom plate 14e and the second joint portion 20, so that the outer bottom plate 14e and the second joint portion 20 can be bent independently. Cuts 27 are also provided between the cover plates 15 so that both the cover plates 15 can be bent independently.

An assembly method and a folding method of the resin folding box 10 configured as described above will be described.
When the resin folding box 10 is assembled, as shown in FIGS. 2A and 2B, the first structural member 25 and the second structural member 26 are melt-bonded at the two ear plate 13 portions. From the folded state, as shown in FIG. 3, the folding lines 12 at the two corners that are not adjacent to each other (the left and right ends of FIGS. 2A and 2B) are slightly opened so as to form a planar rhombus. When further opened from that state, as shown in FIGS. 4 and 5, the outer bottom plate 14b on one short side is opened in a state of being joined to the inner bottom plate 14a at the first joint portion 19, and the other short side is opened. The outer bottom plate 14b is opened in a state of being joined to the outer side bottom plate 14b on the long side by the second joint portion 20. Therefore, the outer bottom plate 14b on the long side is opened, and the inner bottom plate 14a is opened on the inner surface.

  Subsequently, as shown in FIG. 1, when the flat bottom is opened, the two outer bottom plates 14 b on the short side and the outer bottom plate 14 b on the long side are formed in a flat plate shape, and the inner bottom plate 14 a It is formed to be placed on top. At this time, the inner bottom plate 14d that is bent outward by the diagonal fold line 12a of the inner bottom plate 14a can be flattened by pressing the portion of the diagonal fold line 12a from the inner side to the outer side.

  Finally, as shown in FIGS. 6 (a) and 6 (b), after the two cover plates 15 on the short side of the four cover plates 15 are folded inward, the two long side By folding the cover plate 15 inward, the cover plates 15 on the long side are abutted to assemble the resin folding box 10.

  Next, when the assembled resin folding box 10 is folded, the procedure is reverse to the above assembling procedure. That is, after the long side cover plate 15 is opened from the state shown in FIGS. 6A and 6B, the short side cover plate 15 is opened to the state shown in FIG. Next, as shown in FIGS. 4 and 5, the two corners of the diagonal line where the ear plate 13 is located are folded inward so that it is folded at the folding lines 12 at the two corners that are not adjacent to each other (the left and right ends in FIGS. 4 and 5). Press to. At this time, the inner bottom plate 14a, the outer bottom plate 14b on the long side, and the two outer bottom plates 14b on the short side are folded inward, and the inner bottom plate 14d and the outer bottom plate 14e are folded outward along the oblique folding lines 12a. . As shown in FIG. 3, when the two corners of the diagonal line where the ear plate 13 is located are continuously pressed inward, the box is deformed to form a flat rhombus. Finally, when the two corners of the diagonal position where the ear plate 13 is located are pressed strongly, the box is folded into a substantially flat plate shape as shown in FIGS.

The effects exhibited by the resin folding box 10 configured as described above will be described together below.
(1) In the resin folding box 10 of the present embodiment, an oblique folding line 12a extending from one end 12c of the folding line 12 connecting the inner bottom plate 14a and the long side plate 11a toward the opposite side 14c of the inner bottom plate 14a is formed. When the box is folded, the inner bottom plate 14d is configured to be folded outward by the oblique fold line 12a. For this reason, when the folded box is opened and assembled, the inner bottom plate 14d folded by the oblique folding line 12a is flattened by opening the side plate 11 so as to have a flat rectangular shape, and the whole surface of the bottom portion is formed. Be placed. On the other hand, when the assembled box is folded, the inner bottom plate 14d is folded along the oblique folding line 12a.

In this case, the angle θ of the side folded outwardly formed by the diagonal fold line 12a and the opposing side 14c is set to 67.5 to 75.0 °, so that the box is assembled or folded. At this time, the inner bottom plate 14a hits the side plate 11 so that the operation is not hindered. And since the inner bottom plate 14a is laid on the entire bottom surface of the assembled box, there is no need to lay another floor plate in the box, and the contents in the box become unstable or fall off. Is avoided.
In addition, a fold line 12a extending obliquely from the other end portion 12d of the fold line 12 connecting the outer bottom plate 14b and the side plate 11a toward the opposite side of the outer bottom plate 14b facing the fold line 12 is formed. Then, when assembling and folding the box, the outer bottom plate 14b can be folded along the folding line 12a.

  Therefore, according to the resin folding box 10, assembling and folding can be performed smoothly with a single touch, and the stored items can be stored in a more stable state without tilting or falling down. .

  (2) The diagonal fold line 12a of the inner bottom plate 14a is in contact with one end portion 12c of the fold line 12 connecting the inner bottom plate 14a and the long side plate 11a, and is centered on a line 17 perpendicular to the fold line 12 from the one end portion 12c. When the circle 18 is drawn, it is formed so as to extend in the tangential direction of the circle 18, and the radius r of the circle 18 is set to 4 mm or less. For this reason, it is not necessary to form the diagonal fold line 12a strictly from the end of the fold line 12, the allowable range of the diagonal fold line 12a is large, the diagonal fold line 12a can be easily formed, and the diagonal fold line can be formed. The wire 12a can be folded without any trouble.

(3) The fold line 12 can be easily and quickly formed by heat-welding predetermined portions of the side plate 11 and the bottom plate 14 made of resin by hot pressing.
(4) Since the width of the fold line 12 is set to an appropriate width of 7 to 15 mm, the bendability is good and the fold line 12 can be easily folded and the strength of the fold line 12 is maintained. can do.

  (5) An oblique fold line 12b is formed from one end 12c of the fold line 12 on the short side outer base plate 14b adjacent to the inner bottom plate 14a, and the inner bottom plate 14a side is located on the inner side of the oblique fold line 12b. It joined to the outer surface of the baseplate 14a, and was set as the 1st junction part 19. As shown in FIG. Further, the fold line 12 of the short-side outer bottom plate 14b adjacent to the long-side outer bottom plate 14b is connected to the one end portion 12c of the fold line 12 and the other end portion 12d located diagonally to the oblique fold line 12b. The outer bottom plate 14b side longer than the oblique folding line 12b is joined to the outer surface of the outer bottom plate 14b to form the second joint portion 20. In addition, an oblique fold line 12a is provided on the second joint 20 side of the long side outer bottom plate 14b so that the long side outer bottom plate 14e can be folded outward.

For this reason, the outer bottom plate 14b on each long side and the outer bottom plate 14b on the short side can be folded smoothly while supporting the inner bottom plate 14a from the outer surface.
(6) The two adjacent long side plates 11a, the short side plates 11b, the first structural member 25 of the inner bottom plate 14a and the short side outer bottom plate 14b connected thereto, and the other two adjacent long side plates 11a. The short side plate 11b, the long side side outer bottom plate 14b connected to the short side plate 11b, and the second structural member 26 of the short side side outer bottom plate 14b are joined together by the ear plate 13 provided on the long side plate 11a. Yes. Therefore, the resin folding box 10 can be easily manufactured by connecting the two structural members 25 and 26.

  (7) Since the lid plate 15 is connected to each side plate 11 via the fold line 12, the contents accommodated in the resin folding box 10 are effectively protected by the four lid plates 15. Can do.

It should be noted that the above-described embodiments may be modified as follows .

The four cover plates 15 can be omitted, and the resin folding box 10 without the cover plate 15 can be obtained.
The shape of the outer bottom plate 14b on the long side and the outer bottom plate 14b on the short side are changed so that they are arranged on the entire bottom surface in the assembled state so that the inner bottom plate 14a can be supported on the entire bottom surface. It is also possible to configure.

  The slant fold line 12a of the inner bottom plate 14a can be formed thinner than the other fold lines 12 to facilitate folding, and the flatness of the inner bottom plate 14a can be improved when the box is assembled.

The inner bottom plate 14d or the outer bottom plate 14e can be configured to be folded inward along the oblique folding line 12a.
The gripping hole 16 can be omitted or the position, number, size, and shape can be changed as appropriate according to the application.

-Each board can use the hollow structure board which has various forms, such as a column shape and a substantially conical shape, a solid board | plate material, etc. instead of the parallel rib 23. FIG.
・ The bottom and sides of the box are not only rectangular but also square.

  DESCRIPTION OF SYMBOLS 10 ... Resin folding box, 11 ... Side plate, 11a ... Long side plate, 11b ... Short side plate, 12 ... Folding line, 12a ... Diagonal folding line, 12b ... Diagonal folding line, 12c ... One end part, 12d ... Other end part , 13 ... ear plate, 14 ... bottom plate, 14a ... inner bottom plate, 14b ... outer bottom plate, 14c ... opposite side, 14d ... inner bottom plate, 14e ... outer bottom plate, 15 ... lid plate, 17 ... line, 18 ... circle, 19 ... 1st junction part, 20 ... 2nd junction part, (theta) ... angle, r ... radius.

Claims (7)

The four side plates are integrally configured via folding lines provided at the four corners, and the bottom plate is connected to the lower edge of each side plate via the folding line, and the inner bottom plate located on the innermost side of the bottom plates is one. The outer bottom plate connected to the side plate is disposed on the entire bottom surface, and the outer bottom plate connected to the other side plate is configured to support the inner bottom plate, and the two folding lines provided at the four corners are not adjacent to each other. A resin folding box that is folded along a folding line,
A folding line extending obliquely from one end of the folding line connecting the inner bottom plate and the side plate toward the opposite side of the inner bottom plate facing the folding line is formed, and the inner bottom plate extends obliquely when the box is folded. It is configured to be folded outward or inward by a fold line, and the angle of the fold line extending in the diagonal direction and the opposite side between the opposing side is set to 67.5 to 75.0 °. And a folding line extending in a slanting direction from the other end of the folding line connecting the outer bottom plate and the side plate toward the opposite side of the outer bottom plate facing the folding line . . The fold line extending in the oblique direction is in contact with one end of a vertical fold line connecting the inner bottom plate and the side plate, and when drawing a circle having a center on a line perpendicular to the vertical fold line from the one end, the tangential direction of the circle The resin folding box according to claim 1, wherein the resin folding box is formed so as to extend to 4 mm and a radius of the circle is set within 4 mm. The resin folding box according to claim 1 or 2, wherein the folding line is formed by hot pressing. The resin folding box according to claim 3, wherein a width of the folding line is set to 7 to 15 mm. When deployed, one of the outer bottom plates adjacent to the inner bottom plate forms a slanted fold line from one end of the fold line on one outer bottom plate, and the inner bottom plate side of the slanted fold line is located on the inner bottom plate side. A diagonal fold line is formed on the other outer bottom plate from one end of the fold line and the other end of the fold line diagonally located on the other outer bottom plate. The outer bottom plate side facing the inner bottom plate is joined to the outer surface of the outer bottom plate to form a second joint portion, and the outer bottom plate can be folded inward on the second joint portion side of the outer bottom plate facing the inner bottom plate. The resin folding box according to any one of claims 1 to 4, wherein an oblique folding line is provided. The two adjacent side plates and the inner and outer bottom plates connected thereto, and the other two adjacent side plates and the outer bottom plate connected thereto are joined by an ear plate provided on the side plate. The resin folding box according to any one of claims 1 to 5, wherein the resin folding box is provided. The resin folding box according to any one of claims 1 to 6, wherein a lid plate is connected to each of the side plates via a folding line.