PET Tamper-Evident Closure Band Reshaping for Stress-Free Capping
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Solution Overview
Problem
Existing plastic beverage closures with tamper evidence features face challenges in demolding and capping, particularly when using polyethylene terephthalate material, due to the stress caused by conventional engagement features like cams or tabs during demolding and capping processes.
Innovation Solution
The use of a polyethylene terephthalate material with a reduced wall thickness for the tamper evidence band, combined with a reshaping process involving differential heat application, allows the band to engage with the container neck without stress, using a membrane instead of bridges for connection, and employing heat to deform the band for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional engagement features like cams or tabs are used in PET closures, then secure engagement with container neck is achieved, but stress and damage occur during demolding and capping processes
Solution Approach 1:
The patent changes the wall thickness parameter of the tamper evidence band from conventional thickness to a reduced thickness (10%-25% of wall length), making it more flexible and less prone to stress during demolding and capping while maintaining engagement security through laser-induced deformation
Solution Approach 2:
The patent replaces conventional mechanical engagement features (cams or tabs) with a laser-induced deformation mechanism. The tamper evidence band is deformed using laser energy to create engagement with the container neck, eliminating the need for stress-prone mechanical features during assembly and disassembly
2Strength
If wall thickness is reduced for tamper evidence band, then stress during demolding and capping is minimized, but engagement security may be compromised
Solution Approach 1:
The patent utilizes phase transition of the PET material through laser heating. The laser energy temporarily raises the material temperature above its glass transition temperature, allowing the thin-walled band to deform and engage with the container neck, then cools to lock in the engaged position, ensuring both stress minimization and engagement security
Solution Approach 2:
The laser irradiation is applied as a periodic or pulsed action to the tamper evidence band, temporarily softening the material for deformation and engagement, then allowing it to cool and harden in the engaged position, achieving secure engagement without permanent stress
3Ease of manufacture
If membrane connection is used instead of bridges, then demolding process is simplified, but structural integrity may be reduced
Solution Approach 1:
The patent employs a membrane (thin film) structure for the tamper evidence band instead of rigid bridges. The membrane is connected to the closure body and can flex during demolding without breaking, simplifying the manufacturing process while maintaining sufficient structural integrity through its continuous, unbroken design
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
This method simplifies demolding and capping processes, ensuring secure tamper evidence engagement with the container neck while minimizing material stress, allowing the tamper evidence feature to remain on the container after closure removal.
Implementation Method 1
The annular tamper evidence band is adapted to be reshaped upon irradiation by a laser without application of external forces
Data Source
AI summary
Closures with a tamper evidence feature that is reshaped to connect it to the container neck are disclosed. Methods and systems for carrying out the methods, and to mold stacks for making the closures are also disclosed. The tamper evidence feature can be a band, a portion of a cylindrical skirt or a panel formed in the cylindrical skirt. The application of heat may deform the band inwardly to create a lip for engaging a flange on the container neck, or it may weld the tamper evidence feature to the flange.