Two-Layer Preform with Interface Vents for Bag-in-Container Delamination
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Solution Overview
Problem
The production of integrally blow-moulded bag-in-containers faces challenges in selecting materials for the inner and outer layers that are compatible for both injection moulding and blow-moulding operations, while also ensuring good delamination properties, and existing solutions are either complex or require expensive separate production lines.
Innovation Solution
An integral two-layer preform is produced by injection moulding the inner layer onto a core, followed by the outer layer, with a core-shell type tool using wedge-shaped pins to create interface vents, allowing for delamination upon gas introduction, and using materials where the outer layer's melting temperature is lower than or equal to the inner layer's, enabling cost-effective production without assembly steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If materials are selected for compatibility in injection moulding and blow-moulding operations, then processing compatibility is improved, but delamination properties deteriorate
Solution Approach 1:
The patent applies parameter changes by carefully selecting and controlling the melting temperatures of the inner and outer layer materials. The outer layer material is chosen to have a melting temperature within 20°C of the inner layer material, creating optimal conditions for delamination during blow-moulding while maintaining processing compatibility during injection moulding. This precise parameter control resolves the contradiction between manufacturing ease and delamination reliability.
Solution Approach 2:
The patent implements local quality by creating distinct material properties at different locations within the preform structure. The inner and outer layers use different polymeric materials with specifically tailored melting temperatures, allowing the interface region to exhibit delamination properties while the bulk materials maintain processing compatibility. This localized differentiation resolves the contradiction between uniform processing behavior and localized delamination capability.
2Adaptability or versatility
If separate production lines are used for inner and outer preforms, then design freedom and material selection are improved, but production cost and complexity increase
Solution Approach 1:
The patent merges the production of inner and outer preforms into a single integrated injection moulding process. By combining both layers in one production line with a specially designed mould system, the patent eliminates the need for separate production lines and assembly operations. This merging maintains design freedom through material selection while significantly reducing production complexity and cost, directly resolving the stated contradiction.
Solution Approach 2:
The patent uses composite materials consisting of two different polymeric materials with specific melting temperature relationships. This composite structure allows both materials to be processed together in a single injection moulding operation while maintaining the ability to delaminate during blow-moulding. The composite material approach enables integrated production without sacrificing design versatility, resolving the contradiction between adaptability and production complexity.
3Reliability
If outer layer melting temperature is lower than or equal to inner layer, then delamination upon gas introduction is improved, but processing compatibility may deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the melting temperature difference between outer and inner layer materials to be within 20°C. This narrow parameter range ensures that the outer layer melts sufficiently to enable delamination upon gas introduction while maintaining compatibility with the injection moulding process. The controlled parameter relationship resolves the contradiction between delamination reliability and processing compatibility.
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
This approach results in cost-effective production of bag-in-containers with excellent delamination properties, using materials like PET, PA, and PE, where the inner and outer layers can be the same, facilitating reproducible and efficient release of the inner bag from the outer layer upon pressurized gas injection.
Implementation Method 1
The melting temperature of the inner layer is greater or equal to the melting temperature of the outer layer... the thus obtained inner layer of said container releases from the thus obtained outer layer upon introduction of a gas at a point of interface of the two layers
Data Source
Figure 1(1)~1
Figure 2
AI summary
The invention is an integral two-layer preform (1) for the production of integrally blow- moulded bag-in-containers (2). The preform has an inner layer (11) and an outer layer (12), wherein the preform forms a two layer container upon blow-moulding, and wherein the thus obtained inner layer of the containerreleases from the thus obtained outer layer upon introduction of a gas at a pointof interface of the two layers. The melting temperature of the inner layer is greater than or equal to the melting temperature of the outerlayer.