Packaging boxes, blanks, and sealing methods for packaging boxes

Abstract

To provide a packaging box that can suppress the decrease in compressive strength. [Solution] The corrugated cardboard packaging box 1 has its cylindrical body 3 height adjusted by a packaging device according to the height of the contents 90. The packaging device includes a creasing section that forms a third fold curve L3 on the walls 10,11 of the cylindrical body 3 according to the height of the contents 90 contained inside the cylindrical body 3, and a cutting section that divides the upper flaps 16,18 by pressing a non-sharp, plate-shaped blade against the corner of the opening 4 and lowering it from the upper end of the first fold curve L1 to the third fold curve L3 of the cylindrical body 3. The cylindrical body 3 has a cut line 21 cut along the first fold curve L1 at the corner of the opening 4. The crushing ratio (Z [mN / (m·Pa)]) of the corrugated cardboard sheet, which is the ratio of the vertical compressive strength (Y [kN / m]) of the corrugated cardboard sheet to the bursting strength (X [kPa]) of the corrugated cardboard sheet constituting the cylindrical body 3, is 3.9 [mN / (m·Pa)] or higher.

Claims

1. A corrugated cardboard packaging box (1, 2) includes a cylindrical body (3) with a closed bottom, and the height of the cylindrical body is changed by a packaging device (5) according to the height of the contents (90), The aforementioned packaging device is A horizontal fold line (L3) is formed on the wall portion (10, 11) of the cylindrical body according to the height of the contents housed inside the cylindrical body through the opening (4) on the top surface of the cylindrical body, and a ruled section (31) is provided to divide the wall portion into side walls (15, 17) and upper flaps (16, 18), The device includes a cutting section (32) which separates the upper flap connected via the vertical ridge by pressing a non-sharp, plate-shaped blade (63) against the corner of the opening and lowering it along the vertical ridge (25) from the upper end of the vertical ridge (25) of the cylindrical body to the horizontal fold line, The cylindrical body has a cut line (21) cut along the vertical ridge at the corner of the opening, A packaging box characterized in that the crushing ratio (Z [mN / (m·Pa)]) of the corrugated cardboard sheet constituting the cylindrical body, which is the ratio of the vertical compressive strength (Y [kN / m]) of the corrugated cardboard sheet to the bursting strength (X [kPa]) of the corrugated cardboard sheet, is 3.9 [mN / (m·Pa)] or more.

2. The cylindrical body has notches (20, 22) cut out downward from the upper edge of the corner of the opening, The packaging box according to claim 1, characterized in that the cut line is cut downward from the lower end of the notch.

3. The cylindrical body has a notch (20) that is cut out in a shape that narrows downward from the upper edge of the corner of the opening, The packaging box according to claim 1, characterized in that the cut line is cut downward from the lower end of the notch.

4. The packaging box according to claim 1, characterized in that the cylindrical body has a pair of guide fold lines (23) formed thereon that are inclined to move away from each other from the lower end of the cut line toward the upper edge of the opening.

5. The packaging box according to claim 1, characterized in that a triangular region enclosed by a pair of imaginary lines that are inclined to move away from each other from the lower end of the cut line toward the upper edge of the opening is flattened in the cylindrical body.

6. The cylindrical body further has a fracture guideline (26) that weakens the upper portion of the longitudinal ridge line including the boundary of the adjacent upper flap, The aforementioned fracture guide line is, A first break line (27) is formed between the corner of the opening and a position corresponding to the maximum height of the packaging box after sealing, It has a second break line (28) formed between the lower end of the first break line and a position corresponding to the minimum height of the packaging box after sealing, The first break line is a perforation formed by alternating first cuts (27A) and first joints (27B). The packaging box according to any one of claims 1 to 5, characterized in that the length of the first cut (H5) is 1 / 8 or more of the crossing distance (H6), which is the maximum height of the blade that contacts the fracture surface of the first break line.

7. The second break line is a perforation line in which the second cut (28A) and the second joint (28B) are arranged alternately. The packaging box according to claim 6, characterized in that the lengths of the first cut, the first joint, the second cut, and the second joint are set such that the second break line is less likely to break than the first break line.

8. A blank characterized by forming a packaging box according to any one of claims 1 to 5.

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