Container Rim and Gasket Geometry for Low Additive Migration
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Solution Overview
Problem
Existing container gaskets suffer from additive migration issues, particularly with plasticizers leaching into the contents, which is challenging to address through reformulation due to conflicting requirements for mechanical, thermal, and chemical resistances, and current solutions increase production complexity and costs.
Innovation Solution
The container design features an annular gasket with an inside radius greater than the rim radius by a specific margin, often less than 0.9mm, and a reduced annular channel depth, combined with a mechanical barrier to minimize gasket exposure, allowing for the use of non-conventional gasket materials and formulations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gasket materials with plasticizers are used to achieve softness and sealing, then sealing performance is improved, but additive migration into container contents increases
Solution Approach 1:
The patent changes the physical parameters of the gasket by reducing its thickness and controlling its radial extent relative to the rim. Specifically, the gasket thickness is reduced to 0.5mm or less, and the inside radius of the gasket is positioned at or within 0.9mm of the rim inside radius. This parameter optimization reduces the total volume of plasticizer-containing material in contact with container contents, thereby reducing additive migration while maintaining sealing effectiveness through precise geometric control.
2Object-generated harmful factors
If gasket material quantity is reduced to minimize migration, then additive migration is reduced, but sealing reliability may be compromised
Solution Approach 1:
The patent optimizes multiple gasket parameters simultaneously: thickness (0.5mm or less), radial position (inside radius at or within 0.9mm of rim inside radius), and material composition. This multi-parameter optimization ensures that the reduced gasket volume minimizes plasticizer migration while the precisely controlled geometric configuration maintains adequate contact area and compression for reliable sealing.
Solution Approach 2:
The patent applies local quality by positioning the gasket material specifically where it is most needed for sealing - at the interface between the closure and rim - rather than using a uniform thick layer throughout. The gasket is concentrated in the critical sealing zone with optimized thickness and radial extent, providing effective sealing where required while minimizing material volume and plasticizer content in non-critical areas.
3Object-generated harmful factors
If gasket thickness is reduced to minimize plasticizer content, then additive migration is reduced, but mechanical strength and durability decrease
Solution Approach 1:
The patent compensates for reduced gasket thickness by optimizing other parameters: the inside radius of the gasket is positioned at or within 0.9mm of the rim inside radius, and the gasket material composition is controlled. This multi-parameter optimization maintains the necessary mechanical strength and durability for withstanding processing and storage conditions while minimizing the total plasticizer content through reduced thickness.
Data Source
Figure 1a~1g
Figure 2a~2b
Figure 3~4
AI summary
A container comprising a container body having a neck, the neck having inner and outer surfaces and a rim extending between tops of the inner and outer surfaces, and the rim defining a circular opening. The closure has a centre panel, the closure defining an annular channel. An annular gasket is disposed in the annular channel and the annular channel receives said rim of said neck such that the annular gasket forms a seal between said rim and said closure. When the container body is closed by the closure, the difference between an inside radius of the annular channel at a channel depth of 0.2mm and an inside radius of said rim is less than substantially 0.9mm.