Ream Wrap Weakness Line for Controlled Opening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Reams of paper wrapped in polymeric films, particularly biaxially oriented polypropylene, are difficult to open without damaging the seal, leading to uncontrolled tearing and increased risk of moisture pickup and physical damage during handling.
Innovation Solution
Incorporating carefully positioned lines of weakness along the length of the wrapping sheet to facilitate controlled opening of the package by aligning them within the overlapping flaps where there are only two layers of film, allowing for easy initiation of a tear without compromising the structural integrity during handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wrap material is made with high mechanical strength seal seams to protect the package during handling, then the package protection is improved, but the package becomes difficult to open and tearing becomes uncontrolled
Solution Approach 1:
The seal seam is segmented into two distinct zones: a strong seal zone for reliable sealing and protection, and a weak zone (line of weakness) for controlled opening. This segmentation allows the package to maintain both high protection during handling and ease of opening by directing the tear to propagate only through the predetermined weak zone rather than the entire seal seam.
Solution Approach 2:
Different mechanical properties are applied to different portions of the seal seam. The majority of the seal maintains high strength for protection, while a specific local portion (the line of weakness) is designed with reduced strength to facilitate controlled opening. This local quality differentiation resolves the contradiction by making the seal strong where needed and weak where opening is required.
2Reliability
If the seal seam strength is higher than the film strength, then the sealing reliability is improved, but uncontrolled tearing propagates through the entire film upon opening
Solution Approach 1:
A line of weakness acts as an intermediary element within the seal seam structure. It serves as a predetermined failure path that mediates between the strong seal requirements and the opening requirements. When opening force is applied, the tear is guided to propagate through this intermediary weak zone rather than causing uncontrolled damage to the entire film structure.
3Ease of operation
If the package is designed to be easy to open, then the opening ease is improved, but the structural integrity and sealed condition may be compromised
Solution Approach 1:
The seal structure is divided into functional segments: strong seal portions that maintain structural integrity and a weak zone portion that enables easy opening. The strong seal zones remain intact after opening, preserving the majority of the package's structural integrity while the weak zone sacrificially fails to provide opening ease.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables neat and easy opening of ream wrap packages while maintaining the sealed condition and structural integrity, reducing the likelihood of damage during handling and use.
Implementation Method 1
Heat is then applied to form an overlapped girth seal along the sheet where the sheet has been coated with a heat sealable coating
Data Source
Figure 1~1b
Figure 2~2b
Figure 3~3b
AI summary
A ream wrap package formed by wrapping a sheet of polymeric film (21) around a stack of paper, the sheet having been severed from a web of polymeric film having at least one line of weakness formed therein in the machine direction (MD) and within a region of the transverse direction (TD) , to form a rectangular tube with sides overlapping, sealing one side to the other to form a girth seal (24) , closing the tube at each end to form an envelope seal with tucked in ends and overlapping flaps (25, 25' , 26,26' ) , at least one of which is trapezoidal, so that in the formed package there is at least one line of weakness (27) extending along the whole length of a surface of the package outside the girth seal, positioned so that it terminates at each end of the package within a region of the TD defined by that portion of the overlapping flaps where there are only two layers of overlapping film.