Container Closure Sealing Element for Low-Migration PVC-Free Seals
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Solution Overview
Problem
PVC-free polymer compositions used in closures are cost-intensive and have poor workability, with liquid components like white oil migrating into container contents, especially when sealing fatty or oily products, leading to high migration values.
Innovation Solution
A polymer composition comprising a butene copolymer with a melting temperature between 30°C and 130°C, combined with other polymers and additives, is used to form a sealing element that minimizes liquid components and ensures low migration and low friction, maintaining effective sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If PVC-free polymer compositions are used in closures, then health safety and environmental compatibility are improved, but manufacturing cost increases and workability deteriorates
Solution Approach 1:
The patent employs composite polymer compositions combining multiple polymers (polyethylene, polypropylene, elastomers) with specific additives to achieve PVC-free formulations that maintain both health safety and manufacturability. The composite structure allows each component to contribute specific properties: polyethylene provides barrier properties, polypropylene adds structural stability, and elastomers ensure sealing performance, all while avoiding PVC's health concerns.
Solution Approach 2:
The invention systematically adjusts compositional parameters including polymer ratios, molecular weights, and additive concentrations to optimize both safety and workability. By controlling the content of liquid components and selecting specific polymer grades with appropriate melting points and flow characteristics, the formulation achieves PVC-free status while maintaining acceptable processing behavior and cost-effectiveness.
2Ease of manufacture
If liquid components like white oil are added to improve workability and flowability, then manufacturing cost decreases, but migration into container contents increases
Solution Approach 1:
The patent carefully controls the type and amount of liquid components used, selecting non-migrating alternatives or minimizing white oil content to levels that prevent migration while preserving necessary flowability for molding operations. The formulation adjusts polymer composition and adds specific lubricants or processing aids that provide workability without the lipophilic migration problems of white oil.
Solution Approach 2:
The invention uses minimal amounts of processing aids and liquid components that are consumed during manufacturing but do not persist in the final product or migrate into contents. This approach replaces significant white oil usage with small quantities of functional additives that serve their purpose during processing then remain inert in the sealed container.
3Quantity of substance
If white oil is used as a component in the polymer composition, then cost is reduced, but migration into oily or fatty contents is increased
Solution Approach 1:
The patent modifies the formulation by either eliminating white oil entirely or reducing its content to trace amounts, replacing it with polymer blends and alternative additives that provide similar cost benefits without the migration issue. The selected polymer composition achieves cost-effectiveness through optimized material selection rather than reliance on migratory liquid components.
Solution Approach 2:
The invention extracts or removes white oil from the polymer composition to eliminate the migration problem while maintaining cost-effectiveness through alternative material selections. The formulation achieves necessary workability and sealing properties without incorporating lipophilic substances that would migrate into fatty or oily container contents.
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
The composition achieves manufacturability at acceptable costs with very low migration values and low friction, ensuring high tightness and durability of sealed containers, reducing oxygen ingress and maintaining content integrity.
Implementation Method 1
The sealing element comprises a polymer composition which comprises a butene copolymer with a melting temperature Tm between 30° C. and 130° C.
Data Source
AI summary
The invention relates to a container closure (1, 21, 41, 61) with a sealing element (3, 23, 43, 63). The sealing element (3, 23, 43, 63) comprises a polymer composition. The polymer composition comprises a butene copolymer. The butene copolymer has a melting temperature Tm of between 30° C. and 130° C., wherein the melting temperature Tm is determined by the second heating curve of a DSC measurement at a heating rate of 10° C. min-1.