Beverage Can End Using AA3xxx Alloy and Polypropylene Coating
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Solution Overview
Problem
Existing beverage cans face challenges in achieving internal pressure stability using AA3xxx aluminum alloys for the can end, which are compatible with the can body, while also ensuring economic production and improved recycling behavior.
Innovation Solution
A beverage can design featuring a can end made from an AA3xxx aluminum alloy coated with an adhesion promoter layer and a polypropylene layer, which provides the necessary internal pressure stability and facilitates recycling by using a uniform alloy concept.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If AA3xxx aluminum alloy is used for the can end to maintain uniform alloy concept and improve recycling, then recyclability is improved, but internal pressure stability deteriorates due to lower magnesium content
Solution Approach 1:
The patent applies composite materials by combining AA3xxx aluminum alloy with a polypropylene coating layer to achieve both uniform alloy concept for recycling and sufficient internal pressure stability. The composite structure allows the metal substrate to provide structural integrity while the coating provides additional pressure resistance and surface protection.
Solution Approach 2:
The patent changes the parameters of the aluminum alloy by specifying precise compositional ranges (e.g., Si: 0.03-0.15 wt.%, Fe: 0.03-0.15 wt.%, Mn: 0.01-1.0 wt.%, Mg: 0.1-0.5 wt.%) to optimize both recyclability and mechanical properties. The controlled parameter changes enable the alloy to maintain uniformity for recycling while achieving sufficient pressure stability.
2Adaptability or versatility
If AA3xxx aluminum alloy is used for the can end with uniform alloy concept, then recycling behavior is improved, but material thickness must be increased to provide necessary internal pressure stability, worsening economic production
Solution Approach 1:
The patent uses composite materials (AA3xxx alloy + polypropylene coating) to enhance the functional properties of the can end without increasing material thickness. The coating layer provides additional pressure resistance and surface protection, allowing thin-walled design that is both economical and recyclable.
Solution Approach 2:
The patent optimizes the alloy composition parameters to achieve the best balance between mechanical properties and recyclability. By controlling element concentrations within specific ranges, the alloy achieves sufficient strength at reduced thickness while maintaining uniform composition for efficient recycling.
3Reliability
If AA5xxx aluminum alloy with higher magnesium content is used for the can end to provide internal pressure stability, then internal pressure stability is improved, but recyclability deteriorates due to incompatibility with AA3xxx can body alloy
Solution Approach 1:
The patent applies homogeneity by using the same AA3xxx aluminum alloy for both the can body and can end, ensuring uniform composition throughout. This homogeneous alloy structure enables complete recyclability while the controlled composition (particularly Mg: 0.1-0.5 wt.%) provides sufficient pressure stability without the need for higher-magnesium AA5xxx alloys.
Solution Approach 2:
The patent combines the homogeneous AA3xxx alloy with a polypropylene coating to achieve both recyclability and enhanced pressure stability. The coating reinforces the can end structurally, allowing the use of lower-magnesium, more recyclable alloy composition.
4Reliability
If different aluminum alloy systems (AA3xxx and AA5xxx) are used for can body and can end, then internal pressure stability is improved, but recycling difficulty increases due to incompatible alloy systems
Solution Approach 1:
The patent implements homogeneity by using a single AA3xxx aluminum alloy system for both the can body and can end, eliminating alloy incompatibility issues. The uniform composition (Al-Si-Fe-Mn-Mg system) throughout the entire can enables straightforward recycling processes without the complexity of separating and processing different alloy types.
Solution Approach 2:
The patent uses a composite structure of AA3xxx alloy with polypropylene coating to achieve the functionality previously requiring AA5xxx alloy. This composite approach maintains alloy uniformity for simple recycling while providing sufficient pressure stability through the combined metal-coating structure.
Data Source
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AI summary
The invention relates to a beverage can (1) consisting of a can body (2) for holding the beverage and a can lid (3) for closing the can body, wherein the can body is made of an AA3XXX type aluminum alloy. The invention also relates to an aluminum alloy strip (6) for manufacturing a can lid (2) for a beverage can (1) and the use of the aluminum strip. The objective of proposing a beverage can that consists of a uniform alloy concept, is economically producible, and exhibits improved recycling properties is achieved by the fact that the can lid is made of an AA3xxx type aluminum alloy and has a coating, at least partially, preferably completely, comprising an adhesion promoter layer (8) and a polymer layer (9) with a thickness of 10-100 µm. Preferably, the coating is arranged on the side of the can lid facing the can body.