Envelope Closure with Coextruded Tear Band for Tamper Evidence
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Solution Overview
Problem
Existing closures for containers, such as envelopes, fail to provide a secure permanent closure while allowing easy and controlled opening, often resulting in unintended damage or inability to reseal after opening.
Innovation Solution
A closure system featuring a coextruded tear band with a polymeric material of lower tear strength than the closure panel, allowing for easy opening while maintaining a secure seal, utilizing a polymeric material with high tear strength for the closure panel and a separate polymeric material with higher tensile strength for the tear band, ensuring minimal force is required for opening and generating evidence of opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closure is designed to be permanently sealed, then security and reliability are improved, but ease of opening deteriorates
Solution Approach 1:
The closure panel is segmented into two distinct polymeric layers: a first polymeric material providing structural integrity and sealability, and a second polymeric material forming a tear band with lower tear strength. This segmentation allows the closure to maintain permanent sealing capability while incorporating a dedicated weak point for easy tearing and opening.
Solution Approach 2:
Different regions of the closure panel are assigned different material properties: the majority of the panel uses a first polymeric material with high tear strength for security, while a specific tear band region uses a second polymeric material with lower tear strength. This local quality differentiation enables the closure to be securely sealed overall while having a specific localized area that is easy to tear for opening.
2Ease of operation
If a closure is made easy to open, then ease of operation is improved, but reliability deteriorates due to unintended opening
Solution Approach 1:
The closure is segmented into a robust first polymeric material for overall security and a distinct second polymeric material for the tear band. This segmentation ensures that only the specific tear band region is easy to open, while the rest of the closure maintains high security and resistance to unintended opening.
Solution Approach 2:
The tear band is created by applying local quality differentiation: a second polymeric material with lower tear strength is applied specifically to form the tear band, while the surrounding closure panel retains the high tear strength of the first polymeric material. This ensures easy opening at the tear band while maintaining overall closure security.
3Device complexity
If a single polymeric material is used for the closure panel, then device complexity is reduced, but the ability to provide both secure sealing and easy tearing deteriorates
Solution Approach 1:
The closure panel is constructed as a composite structure with a first polymeric material providing structural integrity and sealability, and a second polymeric material forming a tear band with lower tear strength. This composite material approach enables the single closure panel to deliver both secure sealing and easy tearing functions simultaneously, enhancing adaptability without significantly increasing complexity.
Data Source
AI summary
An envelope has an envelope body formed by opposing panels that define an interior and an opening. A closure is joined to and extends up from the top margin of one panel. The envelope is configured such that the interior surface of the closure is sealable to the other panel to permanently close the envelope opening. The closure includes a closure panel and a tear band coextruded with the closure panel. The tear band is composed of a polymeric material having lower tear strength than the material of the closure panel. The tear band defines a zone of weakness extending along the width of the closure for opening the closure by tearing along the zone of weakness after it is permanently closed.