Peelable Ionomer Casing with Perforated Pull Tabs
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Solution Overview
Problem
Existing food product casings require the use of a knife or cutter for opening, which is inconvenient, especially for children in school lunches, and existing solutions like the laminate casing with polypropylene and Nylon films rely on specific peel strengths to open, which may not always function effectively.
Innovation Solution
A three-film laminate casing comprising a polyolefin film, a polyamide film, and a peelable ionomer film, with perforations forming pull tabs that allow easy tearing and separation without inhibiting the seal, enabling the casing to open without tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a knife or cutter is used to open the casing, then the casing can be opened effectively, but it requires additional tools and is inconvenient for children
Solution Approach 1:
The casing is divided into separate layers with different peel strengths. The outer polypropylene layer is designed to tear easily at perforations, while the inner Nylon layer remains intact. This segmentation allows the casing to be opened without tools by exploiting the weak interface between layers.
Solution Approach 2:
The casing has non-uniform peel strength at different locations and interfaces. The interface between the outer polypropylene and Nylon has lower peel strength than the interface between the inner polypropylene and Nylon. This local variation in quality enables selective tearing at desired locations without affecting the overall seal integrity.
2Reliability
If the seal strength is increased to ensure reliable sealing, then the sealing reliability improves, but the casing becomes difficult to open without tool assistance
Solution Approach 1:
The seal has locally varied peel strength through the laminate thickness. The outer polypropylene/Nylon interface has lower peel strength than the inner polypropylene/Nylon interface. This allows the seal to maintain strong bonding overall while providing a weak point for easy opening at the outer layer.
Solution Approach 2:
The sealing structure is segmented into multiple layers with different functions. The outer polypropylene layer provides easy-tear opening capability, the Nylon layer provides barrier properties and strong adhesion to the inner polypropylene, and the inner polypropylene layer provides seal integrity. This segmentation resolves the contradiction between strong sealing and easy opening.
3Ease of operation
If the casing is designed to open easily without tools, then ease of operation improves, but the seal may fail or the product integrity may be compromised
Solution Approach 1:
The laminate is segmented into three layers: outer polypropylene (easy to tear), Nylon (strong adhesion and barrier), and inner polypropylene (seal integrity). When opened, only the outer layer tears at the perforations, while the inner layer and seal remain intact, maintaining product integrity.
Solution Approach 2:
The peel strength is locally optimized at each interface. The outer polypropylene/Nylon interface has low peel strength for easy opening, while the inner polypropylene/Nylon interface has high peel strength to maintain seal integrity during opening. This local quality differentiation resolves the contradiction between easy opening and seal reliability.
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 casing can be easily opened by pulling the tabs, allowing access to the contents without tools, and the specific film combinations ensure reliable separation without seal failure, providing a convenient and functional packaging solution.
Implementation Method 1
The peelable ionomer film constitutes the outside layer of the cylindrical casing... The parts of the strip where sealing takes place are shown at S1 and S2 in Figure 1. It will be seen that they are positioned just inwardly of the lines of perforations 18, 22. Consequently the edge zone of the strip in which the perforations 18 are formed projects from the seal 24 as shown in Figure 3. It is possible to open a filled casing by prising up the free edge of the laminate, gripping one of the tabs 20, and pulling it in the direction of the arrow A in Figure 3. The laminate tears along the perforations 18 which bound the tab 20 that is being pulled. Continuing to pull on the tab 20 results in the tear lines extending into the laminate beyond the ends of the perforations 18. Because of the nature of the seal between the films 12 and 16, the peeling action is not inhibited by the presence of the seal and the two films readily separate despite the presence of the seal.
Data Source
Figure 1~2
Figure 3~4
AI summary
An elongate strip (10) is disclosed which can be manipulated into a cylindrical shape to form a casing for a food product. The strip comprises films of synthetic plastics material which are laminated together. One of the two outer films of the laminate is a peelable ionomer and the other is an olefin. A plurality of web weakening formations (18) for facilitating initiation of transverse tearing of the web are provided along one of the longitudinal edges of the web. The formations constitute the boundaries of a plurality of pull tabs (20). The weakening formations can be lines of perforations extending inwardly from said one edge of the web