Peelable Heat-Sealable Lid Structure for Clean Glass Container Opening
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Solution Overview
Problem
Existing seals for glass containers with stopper or cap closures, such as those used for dry food products, leave metallic residues on the drinking glass during peeling and are difficult to remove in a single step, potentially contaminating the contents.
Innovation Solution
A double-piece seal comprising a lid and a support, where the lid includes a thin reinforcing film under a conductive material, allowing the seal to be peeled off without leaving metallic traces and enabling piercing with fingers, achieved through a combination of a reinforcing film with a thickness of less than 6 µm and a conductive sheet with sufficient thickness for heat-sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick aluminum foil is used for heat-sealing, then heat conduction is sufficient, but the lid cannot be peeled off in one go and leaves metallic residues on the drinking glass
Solution Approach 1:
The lid is divided into multiple functional layers: a thin conductive material layer (20-40 μm) for heat sealing, a reinforcing film layer (4-6 μm) for structural integrity and single-step peeling, and a heat-sealable film layer for bonding to the rim. This segmentation allows each layer to perform its specific function optimally without compromising the others.
Solution Approach 2:
The lid is constructed as a composite structure combining different materials with complementary properties: conductive material (aluminum or steel) for heat induction, reinforcing film (polyester, polyamide, or polypropylene) for mechanical strength and clean peeling, and heat-sealable film (polyolefin or ionomer) for adhesive bonding. This composite approach resolves the contradiction between heat conduction and peeling ease.
2Reliability
If aluminum foil is used for heat-sealing, then heat conduction is achieved, but metallic residues are left on the drinking glass contaminating the contents
Solution Approach 1:
A reinforcing film layer acts as an intermediary between the conductive material and the external environment. This intermediate layer prevents direct contact between the conductive material and the drinking glass, thereby eliminating metallic residues while still allowing heat to pass through for effective sealing.
Solution Approach 2:
The reinforcing film is designed as a thin flexible layer (4-6 μm) that covers the conductive material. This thin film is sufficient to prevent metallic contamination but thin enough to allow heat penetration, solving the problem of both contamination prevention and heat-sealing effectiveness.
3Ease of operation
If a reinforcing layer is added to the lid, then the lid can be pierced with fingers and peeled in one go, but the structure becomes more complex
Solution Approach 1:
The reinforcing film is applied locally only where needed - as a thin layer (4-6 μm) on the underside of the conductive material. This localized reinforcement provides the necessary structural integrity for finger-piercing and single-step peeling without unnecessarily complicating the overall lid structure or increasing material usage.
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 seal can be removed in a single step without leaving metallic residues, maintaining container hygiene and adhering to consumer habits, suitable for mass-market products like freeze-dried coffee and spreads.
Implementation Method 1
Heat sealing is made possible by the combined action of a conductive material, inserted within the thickness of the seal, which heats up under the effect of electrical induction
Implementation Method 2
Heat sealing is made possible by the combined action of a conductive material, inserted within the thickness of the seal, which heats up under the effect of electrical induction
Implementation Method 3
causing the sealing film or varnish on the rim to soften
Data Source
AI summary
The invention relates to a heat-sealing two-piece seal for sealing a container having a stopper or a cap-type closure, comprising a support temporarily secured to a lid comprising a sheet of conductive material, characterised in that the sheet of conductive material is provided on its lower face with a reinforcing film having a thickness of less than 6 μm, on the lower face of which a heat-sealing film is applied.