Packaging box, blank, and method for sealing packaging box

The corrugated cardboard packaging box design with a cut line and packaging device maintains compressive strength by adjusting height through creasing and cutting, addressing the loss of structural integrity in existing designs.

WO2026120959A1 Publication Date: 2026-06-11RENGO CO LTD
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Patent Information

Application Number
PCT/JP2025/038492
Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
Priority Date
2025-07-28
Filing Date
2025-11-04
Publication Date
2026-06-11

AI Technical Summary

Technical Problem

Existing cardboard packaging boxes experience a decrease in compressive strength when their height is adjusted to accommodate different-sized contents, leading to a loss of structural integrity.

Method used

A corrugated cardboard packaging box design with a cylindrical body that allows height adjustment by forming a cut line along the longitudinal ridge at the top surface, using a packaging device with creasing and cutting mechanisms to form horizontal folds and divide the walls, maintaining a crushing ratio of 3.9 [mN/(m·Pa)] or more.

Benefits of technology

The solution effectively maintains the compressive strength of the packaging box by ensuring the vertical compressive strength of the corrugated cardboard sheet is sufficient relative to its bursting strength, even when the height is changed to fit various contents.

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Abstract

A corrugated cardboard packaging box (1) includes a cylindrical body (3) with a closed bottom face, and can be broken along the vertical ridge lines (L1) of the cylindrical body (3) to thereby change the height of the cylindrical body (3) in accordance with the height of an object (90) to be accommodated therein. The cylindrical body (3) has cut lines (21) that are cut along the vertical ridge lines (L1) at corners of an opening part (4) of a top surface. The vertical ridge lines (L1) are portions excluding lead lines on which perforations are formed. The cut lines (21) are formed above positions at which the maximum height (H1) of the packaging box (1) after sealing is obtained. The compression-to-failure ratio (Z [mN / (m·Pa)]) of a corrugated cardboard sheet constituting the cylindrical body 3, which is a ratio of the vertical compression strength (Y [kN / m]) of the corrugated cardboard sheet to the burst strength (X [kPa]) of the corrugated cardboard sheet, is 3.9 [mN / (m·Pa)] or more.
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