Butt-Welded Multilayer Film Packaging with Reinforced Joint
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Solution Overview
Problem
Existing packaging technologies face challenges in achieving strong and aesthetically pleasing butt-welded joints in multilayer films, particularly in tubular bodies, due to issues like leakage, low strength at the weld zone, and visible welding zones, which are exacerbated by the use of metal foils and non-weldable layers.
Innovation Solution
A method involving a multilayer film structure with a weldable layer and a functional layer, where the ends are partially butt-welded and reinforced with a thin strip bonded onto the functional layer to enhance the joint strength, and optionally covered with a coating layer to improve aesthetics and hygiene, ensuring the strip is trapped within the structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a multilayer film with non-weldable functional layer is butt-welded, then aesthetic properties are improved with almost invisible welding zone, but the strength at the weld zone becomes low and commercial use becomes risky
Solution Approach 1:
The film structure is segmented into distinct functional layers (non-weldable aesthetic layer) and weldable layers. The welding operation is segmented to affect only the weldable layers, leaving the functional layer partially unwelded to maintain aesthetics while ensuring structural integrity through dedicated weldable components.
Solution Approach 2:
Weldable layers act as intermediary elements between the non-weldable functional layer and the welding process. These intermediary layers enable the welding operation to proceed without directly affecting the aesthetic functional layer, thus resolving the contradiction between appearance and strength.
2Strength
If metal foil strip is used to reinforce the weld zone, then strength at the weld zone is improved, but the aesthetics of the packaging deteriorates due to visible strip
Solution Approach 1:
The film structure incorporates local quality by having different layers with different properties at different locations. The weldable layers are positioned specifically at the weld zone to provide reinforcement, while the functional layers maintain their aesthetic properties in visible areas. This localized functional differentiation resolves the contradiction between strength and aesthetics.
3Ease of manufacture
If the non-weldable layer is set back from the ends of the film, then welding of the film over its entire thickness is enabled, but the strength at the weld remains lower than the strength of the film
Solution Approach 1:
The welding action is applied partially, affecting only the weldable layers and leaving the functional layer partially unwelded. This partial welding approach enables the welding operation to proceed without compromising the aesthetic functional layer, while the weldable layers provide sufficient structural reinforcement to achieve the desired strength.
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 achieves packaging with weld zone strength equivalent to the film, negligible thickness variation, and improved aesthetic properties, allowing for seamless printing and enhanced barrier properties without visible welding zones, suitable for various applications including tubular bodies.
Implementation Method 1
A first welding method consists in producing a joint known as a 'wrong side-to-wrong side' joint in which the lower face of the film is welded to itself
Implementation Method 2
said strip being bonded onto the functional layer
Data Source
AI summary
Packaging produced from a thermoplastic film of which the ends are placed so that they abut, said film being composed of several layers, including at least a first weldable layer and a second layer of which the butt-welding is only partial or non-existent, and at least one thin strip covering said ends and being directly attached to one of the faces of the second layer, the difference in the melting point between the first layer and the other layer or layers being greater than 20° C.