Laminated Metal Sheet for Can Lid Resolving Feathering
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Solution Overview
Problem
Existing laminated metal sheets for can lids face challenges in achieving simultaneous improvements in flavor-retaining, barrier, and can-opening properties, particularly due to the phenomenon of feathering, which affects market value and sanitary conditions.
Innovation Solution
A laminated metal sheet with a polyester resin layer composed of two distinct layers, where the A layer has a lower melting point and the B layer has a higher orientation property, controlled through temperature and pressing pressures during manufacturing, to enhance adhesiveness and prevent feathering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer polyester resin coating is applied to the metal sheet, then the manufacturing process is simple, but the feathering resistance and can-opening property are insufficient
Solution Approach 1:
The polyester resin layer is divided into two distinct layers: a first polyester resin layer (A layer) with lower melting point (80-100°C) and lower orientation, and a second polyester resin layer (B layer) with higher melting point (100-120°C) and higher orientation. This segmentation allows each layer to perform its specific function - the A layer provides flexibility and adhesion while the B layer provides feathering resistance and structural integrity during can-opening
Solution Approach 2:
Different regions of the polyester resin coating have different properties tailored to specific requirements. The A layer near the metal sheet has lower orientation and melting point for good adhesion and flexibility, while the B layer on the outer surface has higher orientation and melting point for feathering resistance. This local differentiation of properties resolves the contradiction between manufacturing simplicity and feathering resistance
2Reliability
If the polyester resin layer has high orientation to prevent feathering, then the feathering resistance improves, but the flavor-retaining property and barrier property deteriorate
Solution Approach 1:
The patent applies different orientation levels at different locations within the resin layer. The B layer (outer layer) has high orientation (I0°/I90° ≥ 3.0) to prevent feathering, while the A layer (inner layer adjacent to metal sheet) has low orientation (I0°/I90° ≤ 1.5) to maintain flavor-retaining and barrier properties. This spatial differentiation resolves the contradiction between feathering resistance and flavor preservation
Solution Approach 2:
The polyester resin coating is designed as a composite structure with two layers having different compositions and properties. The A layer contains polyester resin with specific characteristics for flavor retention, while the B layer contains polyester resin optimized for feathering resistance. This composite approach allows simultaneous achievement of opposing properties in different layers
3Object-generated harmful factors
If the polyester resin layer has high adhesion to the metal sheet, then the barrier property improves, but the can-opening property and feathering resistance worsen
Solution Approach 1:
The patent creates different adhesion characteristics at different interfaces. The A layer adjacent to the metal sheet has high adhesion (providing good barrier property), while the B layer on the outer surface has lower adhesion that allows controlled separation during can-opening. This local differentiation of adhesion properties resolves the contradiction between barrier performance and can-opening functionality
Solution Approach 2:
The resin system is segmented into two layers with different adhesion characteristics. The A layer provides strong adhesion to the metal sheet for barrier protection, while the B layer provides controlled adhesion for clean separation during opening. This segmentation allows each layer to optimize its adhesion property for its specific function
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 solution effectively improves feathering resistance, ensuring the laminated metal sheet maintains its integrity and appearance while opening, thereby enhancing the market value and sanitary conditions of the can lids.
Implementation Method 1
the A layer includes a molten layer where the value of the ratio of a peak intensity I0° to a peak intensity I90° is 1.5 or less
Implementation Method 2
the B layer includes an orientation layer where the value of the ratio of the peak intensity I0° to the peak intensity I90° is 3.0 or more
Data Source
AI summary
A laminated metal sheet for a metal container lid includes a polyester resin layer formed on a metal sheet. The polyester resin layer is composed of an A and a B layer, wherein the melting point of the A layer is lower than the melting point of the B layer by 20° C. or more, the A layer includes a molten layer where the value of the ratio of a peak intensity I0° to a peak intensity I90° is 1.5 or less, the B layer includes an orientation layer where the value of the ratio of the peak intensity I0° to the peak intensity I90° is 3.0 or more, the thickness of the A layer is within the range from 5 μm or more to less than 30 μm, and the thickness of the B layer is within the range from 0.5 μm or more to less than 6.0 μm.