Zipper-like Closure Strip with Bimaterial Opening Indicator
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Solution Overview
Problem
Existing closure strips for bags, which incorporate an opening indicator, often malfunction by tearing the bag walls instead of the indicator, and their manufacture is complicated by the presence of the U-shaped web, leading to interference with traditional forming machines and welding issues.
Innovation Solution
A closure strip with support webs made of materials having different melting temperatures, where the upper part has a lower melting temperature than the lower part, and a line of weakness between the parts to facilitate tearing without damaging the bag walls, along with a tab for easier access and a bimaterial composition for improved aesthetics and welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a U-shaped web is used as an opening indicator in the closure strip, then tamper-evidence function is provided, but the bag walls may tear instead of the indicator when the user tries to open the bag
Solution Approach 1:
The support webs are made of bimaterial construction with different melting temperatures in different zones. The first zone has lower melting temperature to facilitate controlled breaking, while the second zone has higher melting temperature to maintain strength and prevent bag wall tearing during the opening process
Solution Approach 2:
The invention changes the melting temperature parameter of the support web materials across different zones. By having the first zone with lower melting temperature and the second zone with higher melting temperature, the opening force is directed to break the indicator rather than damage the bag walls
2Reliability
If a U-shaped web is added to the closure strip for opening indication, then tamper-evidence is achieved, but the manufacturing process becomes more difficult due to extra thickness and interference with forming machines
Solution Approach 1:
The opening indicator function is merged into the closure strip structure itself by making the support webs bimaterial with different melting temperatures. This eliminates the need for a separate U-shaped web component, reducing thickness and simplifying the manufacturing process while maintaining the tamper-evidence function
Solution Approach 2:
The support webs serve multiple functions: they provide structural support for the closure assembly, enable the tamper-evidence function through their bimaterial construction, and facilitate controlled opening. This multi-functionality eliminates the need for separate components and simplifies manufacturing
3Reliability
If a U-shaped web is placed on the closure strip, then opening indication is provided, but the U-shaped walls of the veil risk being welded together by the machine jaws during welding of strips to the bag mouth
Solution Approach 1:
The support webs have different melting temperatures in different zones, with the second zone having higher melting temperature. This local quality difference prevents the support webs from being welded together by the machine jaws during the welding process, as the higher melting temperature zone remains intact under welding conditions
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
Ensures the opening indicator is broken first, providing tamper-evidence while preventing the bag walls from tearing, simplifying the manufacturing process and ensuring the closure strip is securely attached to the bag without welding issues.
Implementation Method 1
the faces of the upper and lower parts which are opposite, called internal faces, are made of materials having different melting temperatures, the melting temperature of the material constituting the internal face of the upper part being lower than the melting temperature of the material constituting the internal face of the lower part
Data Source
Figure 1a~1b
Figure 2~5
Figure 6
AI summary
The invention relates to a closure strip (20) for a bag (10), comprising two support webs (21) provided, on their opposing internal surfaces and at a distance from their longitudinal edges, with at least one longitudinal closure assembly (22), each support web (21) comprising two parts, - a first (211) of said parts, called the upper part, extending longitudinally in an upper part of the support web (21), and - a second part (212), called the lower part, extending longitudinally in a lower part of the support web (21), in which, for at least one of the webs (21), the faces (211a, 212a) of the opposing upper and lower parts (211, 212), called the internal faces, are made of materials having different melting points,characterized in that the melting temperature of the material constituting the inner face (211a) of the upper part (211) is lower than the melting temperature of the material constituting the inner face (212a) of the lower part (212).